KR20050020984A - (Meth)acrylic Esters of Polyalkoxylated Trimethylolpropane - Google Patents

Abstract

The present invention relates to (meth) acrylic acid esters of novel polyalkoxylated trimethylolpropanes of the general formula (I). The invention also relates to a simplified process for the preparation of said esters and to the use of the reaction mixtures obtainable thereby.

<Formula I>

Where

AO is independently EO, PO or BO, where EO is O-CH ₂ -CH _2- , and PO is independently O-CH ₂ -CH (CH ₃ )-or O-CH (CH ₃ ) -CH ₂ -Is independently O-CH ₂ -CH (CH ₂ -CH ₃ )-or O-CH (CH ₂ -CH ₃ ) -CH _2- ,

p ₁ + p ₂ + p ₃ is 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48 , 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73 , 74 or 75,

R 1, R 2 and R 3 are independently H or CH ₃ .

Description

(Meth) acrylic esters of polyalkoxylated trimethylolpropane {(Meth) acrylic Esters of Polyalkoxylated Trimethylolpropane}

Preparation of crude acrylated esters useful as SAP crosslinkers

SAP-crosslinkers were prepared by esterifying alkoxylated trimethylolpropane with acrylic acid, for example by removing water by azeotropic distillation. The esterification catalyst in the example was sulfuric acid. The reaction was introduced upon initial charge with a methylcyclohexane co-agent with a stabilizer mixture consisting of hydroquinone monomethyl ether, triphenyl phosphite and hypophosphoric acid. The reaction mixture was then heated to about 98 ° C until azeotropic distillation started. During azeotropic distillation, the temperature of the reaction mixture rose. The amount of water removed was measured. Distillation was stopped at least once the theoretical amount of water had been removed. The co-agent was then removed during vacuum distillation. The product was cooled and used as crosslinker in SAP product.

Since the water removed during the esterification contained acrylic acid and the acrylic acid was removed during vacuum distillation of the co-agent, the conversion and yield of the reaction were not accurately measured. Similarly, the crude ester still contained free acrylic acid titrated with the catalyst (acid value).

Parts are parts by weight unless otherwise indicated.

Preparation of ester

Acid value was measured according to DIN EN 3682.

Example 1 Preparation of Alkoxylated Trimethylolpropane

a)

77 g of trimethylolpropane, together with 0.5 g of 45% KOH in water, was placed in an autoclave as an initial charge and dehydrated at 80 ° C. and reduced pressure (about 20 mbar). Subsequently, 759 g of ethylene oxide were added at 145 to 155 ° C. and reacted under elevated pressure at this temperature. The reaction was terminated when no further pressure change was observed. Thereafter, the reaction mixture was stirred at 150 ° C. for an additional 30 minutes. 167 g of propylene oxide was then added at elevated pressure at 120-130 ° C. over an extended period of time and reacted as well. After purging with inert gas and cooling to 60 ° C., the catalyst was separated by addition of sodium pyrophosphate and subsequent filtration.

b)

77 g of trimethylolpropane, together with 0.5 g of 45% KOH in water, was placed in an autoclave as an initial charge and dehydrated at 80 ° C. and reduced pressure (about 20 mbar). Thereafter, 1264 g of ethylene oxide were added at 145 to 155 ° C., and the reaction was carried out at elevated temperature at elevated temperature. The reaction was terminated when no further pressure change was observed. The reaction mixture was then stirred at 150 ° C. for an additional 30 minutes. 333 g of propylene oxide was then added at elevated pressure over an extended period of time at 120 to 130 ° C. and reacted as well. After purging with inert gas and cooling to 60 ° C., the catalyst was separated by addition of sodium pyrophosphate and subsequent filtration.

Example 2 Preparation of Acrylic Ester

a)

1427 parts of about 30-in ethoxylated and 5-in propoxylated trimethylolpropane (according to Example 1) were esterified with 216 parts of acrylic acid and 5 parts of sulfuric acid in 345 parts of methylcyclohexane. The preparation used was 3 parts hydroquinone monomethyl ether, 1 part triphenyl phosphite and 1 part hypophosphoric acid. After 44 parts of water was removed, the coagulant was removed by vacuum distillation. The product was purified through a K300 filter. The acid value was measured. 96 parts of acrylic acid were added to adjust the viscosity. The viscosity of the nearly colorless product (iodine color number 0-1) was about 330 mPas.

b)

2383 parts of about 50- ethoxylated and 10-propoxylated trimethylolpropane (according to Example 1) were esterified with 216 parts of acrylic acid and 5 parts of sulfuric acid in 345 parts of methylcyclohexane. The preparation used was 3 parts hydroquinone monomethyl ether, 1 part triphenyl phosphite and 1 part hypophosphoric acid. After 44 parts of water was removed, the coagulant was removed by vacuum distillation. The product was purified through a K300 filter. The acid value was measured. 96 parts of acrylic acid were added to adjust the viscosity. The viscosity of the nearly colorless product (iodine color number 0-1) was about 350 mPas.

Preparation of Hydrogels

To determine the quality of surface crosslinking, the dried hydrogels can be investigated using the following standard methods.

Test Methods

a) centrifugal retention capacity (CRC)

This method measures the free swelling of the hydrogel in tea bags. 0.2000 +/- 0.0050 μg of dry hydrogel (particle size 106 to 850 μm) was measured and sealed in a tea bag having a size of 60 × 85 μm. The tea bag was allowed to stand for 30 minutes in an excess of 0.9% by weight sodium chloride solution (> 0.83 L sodium chloride / 1 g polymer powder). The teabag was then centrifuged at 250 g for 3 minutes. The amount of liquid was measured by weighing the centrifuged tea bags.

b) Absorbency under load (AUL) (0.7 psi)

The measuring cell for measuring AUL 0.7 psi was a Plexiglass cylinder with an internal diameter of 60 mm and a height of 50 mm. A stainless steel sieve with a mesh size of 36 μm was adhesively attached to its lower surface. The measuring cell also includes a plastic plate with a diameter of 59 mm, and a balance that can be placed in the measuring cell with the plastic plate. The plastic plate and scale together are 1345 g. The AUL 0.7 psi was measured by weighing the empty plexiglass cylinder and plastic plate and recording it as W ₀ . Subsequently, 0.900 +/− 0.005 g of hydrogel-forming polymer (particle size distribution 150-800 μm) was measured and placed in a Plexiglas cylinder and distributed very uniformly throughout the bottom of the stainless steel sieve. The plastic plate was then left in the plexiglass cylinder, the whole unit was measured, and the weight was recorded as W _a . The balance was then left on a plastic plate in the plexiglass cylinder. Subsequently, a ceramic filter plate with a diameter of 120 mm and a porosity of zero is placed in the center of a Petri dish with a diameter of 200 mm and a height of 30 mm, and placed on the surface of the liquid which is horizontal to the surface of the filter plate and not to the surface of the wet filter plate. Sufficient 0.9 wt% sodium chloride solution was introduced. Circular filter paper (S & S 589 Schwarzband from Schleicher & Schull) with a diameter of 90 mm and a pore size of <20 μm was then left on the ceramic plate. The plexiglass cylinder containing the hydrogel-forming polymer was then left on top of the filter paper along with the plastic plate and the balance and left there for 60 minutes. At the end of this period, the complete unit was removed from the filter paper and the petri dish and then the balance was removed from the plexiglass cylinder. Plexiglas cylinders containing swollen hydrogels were measured with a plastic plate and the weight was recorded as W _b .

The AUL was calculated according to the following formula:

AUL 0.7 psi [g / g] = [W _b -W _a ] / [W _a -W ₀ ]

AUL 0.5 psi was measured in a similar manner at lower pressures.

c) The 16-hour extractable amount value was measured similarly to the description of lines 1 to 19 of page 13 of EP-A1 811 636.

d) a method for determining the residual level of crosslinking agent of the hydrogel

To determine the level of residue that is a non-converted crosslinker, this residual crosslinker was initially extracted from the dried hydrogel by double extraction. At the end of this, 0.400 g of dry hydrogel and 40 g of 0.9 wt% sodium chloride solution were measured and placed in a sealable and centrifugable ampoule. 8 μml of dichloromethane was added, the ampoule was sealed and then shaken for 60 minutes. The ampoule was then immediately centrifuged at 1500 rpm for 5 minutes to separate the organic phase cleanly from the aqueous phase.

50 μl of monoethylene glycol was measured and placed in a second ampoule, about 5-6 ml of dichloromethane extract was added, and the weight of the extract was accurately measured to 0.001 g. The dichloromethane was then evaporated at 50-55 ° C. and after cooling the residue was dissolved in 2 ml of methanol-water mixture (50 parts by volume each). It was shaken for 10 minutes and then filtered through a PTFE 0.45 μm filter. The samples thus obtained were separated by liquid phase chromatography and analyzed by mass spectrometry. The serial dilutions of the same crosslinker used were quantified.

The chromatography column used was Zorbax Eclipse XDB C-8 (150 x 4.6 mm-5 μm), and the precolumn used was Zorbax Eclipse XDB C-8 (12.5 x 4.6 mm-5 μm). The mobile phase used was a 75/25 methanol / water mixture.

The gradient process is as follows:

Time (min) % Methanol % Water 0 75 25 3 75 25 4 98 2 8 98 2 9 75 25 14 75 25

The flow rate was 1 μml / min at 1600 μs psi pressure.

Injection volume was 20 μL.

Typical assay time was 14 minutes for the samples.

Detection was performed by mass spectrometry, for example, in the range of 800-1300 m / z (full scan, positive). The instrument used APCI (atmospheric pressure chemical ionization, cationization). For optimization, the capillary temperature was set to 180 ° C., the APCI vaporizer temperature to 450 ° C., the source current to 5.0 μA and the gas flow rate to 80 μm / min.

Individual settings should be performed separately for each crosslinker. At the end of this, a unique peak suitable for subsequent evaluation was determined using a suitable correction solution of the crosslinker. Main peak was generally selected.

The residual crosslinker concentration was then calculated as follows:

CONC _Probe = A _Probe x CONC _Std x VF / A _Std

CONC _probe : desired residual crosslinker concentration in dry hydrogel at mg / kg

CONC _Std : desired residual crosslinker concentration in calibration solution of mg / kg

A _probe : peak area of an extracted sample of dried hydrogel

A _Std : Peak Area of Calibration Solution

VF is the dilution factor:

VF = M _DCM x M _Solv / (M _Probe x M _Extract )

M _DCM is the weight of dichloromethane for extraction.

M _probe is the weight of dry hydrogel.

M _Solv is the weight of methanol-water mixture + monoethylene glycol.

M _extract is the weight of dichloromethane extract.

Calibration must be performed to ensure that the measurement has been performed in the linear range (for example including multiple points in the range of 0 to 50 ppm).

e) saponification index VSI

The ground gel was then further processed in two different ways:

Post Treatment Method 1:

The ground gel was spread evenly in a thin layer on a sieve bottom tray and then dried at 80 ° C. under reduced pressure for 24 hours. This type of drying was very gentle to the product, thus representing the best standard for comparison.

The dried hydrogel was then ground and the sieve fractions of 300-600 μm were isolated.

Post Treatment Method 2:

The ground gel was heat treated at 90 ° C. for 24 hours in an initially sealed plastic bag. It was then evenly spread in thin layers on a sieve bottom tray and dried at 80 ° C. under reduced pressure for 24 hours. This drying takes place in typical manufacturing plants and in this connection simulates drying conditions which typically limit the drying performance and raw material throughput due to the reduced quality.

The dried hydrogel was then ground and the sieve fractions of 300-600 μm were isolated.

Hydrogels obtained according to two workup methods were characterized by measurements relating to tea bag performance (CRC) and also to extractable content and unreacted, levels of residual crosslinker after 16 hours. In addition, if more than 1% by weight was found by measuring the moisture content, this was arithmetically taken into account when determining these properties. Typically, the moisture content will be about 5% by weight.

The measured value was then used to determine the Saponification Index (VSI) of the crosslinker in the gel, which was calculated as follows:

VSI = 0.5 x (CRC ₂ -CRC ₁ ) + 0.5 x (extractable amount ₂ -extractable amount ₁ )

Here, the subscripts indicate post-treatment method 1 and post-treatment method 2 in the same case. As such, the saponification index increased when tea bag performance increased as a result of plant drying and the extractable fraction in the process increased. Two contributions were given at the same weight.

It is generally advantageous to use crosslinkers with a very low saponification index. An ideal crosslinker has a VSI of zero. The use of such crosslinkers has led to an increase in the performance of the plant dryer to the maximum that can be technically carried out without loss of quality. The reason for this is that the degree of crosslinking achieved during the polymerization-and thus the properties of the final product-is no longer changed by hydrolysis during the drying process.

Example 3 Preparation of Superabsorbents Using Acrylic Acid Ester of Example 2 and Other Internal Crosslinkers

Example a

305 g of acrylic acid and 3204 g of 37 wt% sodium acrylate solution were dissolved in 1465 g of distilled water in an acid-resistant plastic tube. 12.2 μg of TMP 15EO triacrylate was added as a crosslinking agent, and also 0.61 μg of V-50 (2,2′-azobis-amideinopropane dihydrochloride) and 3.05 μg of sodium persulfate as initiators. The initiator was advantageously predissolved in one batch of batch water. The batch was stirred thoroughly for several minutes.

Subsequently, nitrogen gas was bubbled through the plastic film covering the solution in the tube in order to remove oxygen and be able to carry out a homogeneous distribution for the crosslinker. Finally, 0.244 μg of hydrogen peroxide dissolved in 5 μg of water and 0.244 μg of ascorbic acid dissolved in 5 μg of water were added. The starting temperature of the reaction should be 11-13 ° C. The reaction solution was about 6 cm deep. After a few minutes the reaction was initiated, proceeded under adiabatic conditions, the insulated tube was allowed to stand for up to 30 minutes and the gel was worked up.

To work up the gel, the gel block was initially broken into pieces and then ground through a meat grinder equipped with a 6 mm grinder plate.

The ground gel was then further processed in two different ways:

Post Treatment Method 1:

The ground gel was spread evenly in a thin layer on a sieve bottom tray and then dried at 80 ° C. under reduced pressure for 24 hours. This type of drying was very gentle to the product and therefore showed the best standard for comparison.

The dried hydrogel was then polished and 300-600 μm sieve fractions isolated.

Post Treatment Method 2:

The ground gel was heat treated at 90 ° C. for 24 hours in an initially sealed plastic bag. It was then evenly spread in thin layers on a sieve bottom tray and dried at 80 ° C. under reduced pressure for 24 hours. This drying takes place in a typical manufacturing plant and in this connection simulates drying conditions which typically limit the drying performance and raw material throughput due to the reduced quality.

The dried hydrogel was then ground and the sieve fractions of 300-600 μm were isolated.

The following additional examples were prepared analogously to Example a:

Example number Crosslinker type Amount used based on acrylic acid monomer Used amount (g) a TMP-3 EO Triacrylate 1 wt% 12.2 g b TMP-15 EO Triacrylate 1 wt% 12.2 g c TMP-20 EO Triacrylate 1 wt% 12.2 g d TMP-30 EO-5 PO Triacrylate 2.0 wt% 24.4 g e TMP-50 EO-10 PO Triacrylate 3.2 wt% 39.0 g f TMP-5 PO-30 EO Triacrylate 2.0 wt% 24.4 g g TMP-10 PO-50 EO Triacrylate 3.2 wt% 39.0 g

The properties obtained for these hydrogels are summarized in Table 2:

Example CRC 1 Extractable amount after 16 hours 1 Residual amount of crosslinking agent 1 CRC 2 Extractable amount after 16 hours 2 Residual amount of crosslinking agent 2 VSI [g / g] [weight%] [ppm] [g / g] [weight%] [ppm] a TMP-3EO 36.6 4.4 857 70.6 44.2 1302 36.9 b TMP-15EO 29.7 2.8 51 43.1 12.6 20 11.6 c TMP-20EO 30.3 2.9 29 41.1 13.1 14 10.5 d TMP-30EO-5PO 30.1 3.1 <10 35.5 7.0 <10 4.7 e TMP-50EO-10PO 30.9 2.8 <10 35.1 5.8 <10 3.6 f TMP-5PO-30EO 29.5 3.1 <10 37.5 9.0 <10 7.0 g TMP-10PO-50EO 30.1 2.6 <10 34.8 6.2 <10 4.1

After school:

The dry typical base polymer powder was prepared from a solution of 0.10% by weight of ethylene glycol diglycidyl ether (Nagase, Japan), 3.35% by weight of water and 1.65% by weight of 1,2-propanediol, where each percentage was Sprayed uniformly (based on the polymer used).

The wet powder was then heat treated in a drying cabinet at 150 ° C. for 60 minutes. This was then sieved one or more times at 850 μm to remove aggregates. The properties of these postcrosslinked polymers were measured.

excuse CRC AUL 0.7 psi b TMP-15EO 29.3 24.0 d TMP-30EO-5PO 29.7 24.3 e TMP-50EO-10PO 30.5 25.0 f TMP-5PO-30EO 29.5 24.9 g TMP-10PO-50EO 29.8 24.7

The present invention relates to (meth) acrylic acid esters of novel polyalkoxylated trimethylolpropanes, simplified processes for the preparation of these esters and to the use of the reaction mixtures so obtainable.

Swellable hydrogel-forming addition polymers known as superabsorbent polymers or SAPs are known from the prior art. It is a network of flexible hydrophilic addition polymers and can be both ionic and nonionic in nature. It can absorb and bind aqueous fluids by forming hydrogels and is therefore preferably used in tampons, diapers, sanitary napkins, incontinence articles, training pants for children, insoles and other hygiene articles for body fluid absorption. Superabsorbents are also used in other fields of the art in which fluids, in particular water or aqueous solutions, are absorbed. Examples of this field include, for example, storage, packaging, transport (packaging materials for sensitive articles, for example flower transport, impact protection); Food sector (fish, fresh meat transportation; absorption of water, blood in fresh fish / meat packs); Medical (wound casts, water-absorbing materials for burn dressings or other exuding wounds), cosmetics (pharmaceutical and pharmaceutical carrier materials, plasters for rheumatism, ultrasonic gels, cooling gels, cosmetic thickeners, sunscreens); Thickeners for oil-in-water or water-in-oil emulsions; Fabrics (gloves, sports clothing, moisture control in fabrics, shoe inserts); Chemical process industrial applications (catalysts for organic reactions, fixation of large functional molecules (enzymes), cohesive adhesives, heat storage media, filter aids, hydrophilic components of polymer laminates, dispersants, liquefying agents); Construction and construction, equipment (powder injection moldings, clay-based superwalls, vibration-suppressing media, aids in tunnel construction in watery lands, for cable sheaths); Water treatment, sewage treatment, water removal (icemaker, reusable sachets); Cleaning; Agriculture (holding of irrigation, watering and dew condensation, compost additives, protection of forests against fungal and insect invasion, delayed release of active ingredients to plants); Fire prevention (flying sparks) (covering the house or house wall with an SAP gel, since water has a very high heat capacity, ignition can be prevented; in the case of a fire such as a forest fire, spraying a SAP gel); Co-extruders in thermoplastic polymers (hydrophilization of multilayer films); The production of films and thermoplastic moldings which can absorb water (eg agricultural films capable of storing rain and dew); SAP-containing films for the storage of fresh fruits and vegetables that can be packed into wet films; SAP stores water released by fruits and vegetables without the formation of compressed droplets and partially re-spins the water on fruits and vegetables to prevent contamination and wilting; SAP-polystyrene coextruded for food packs such as, for example, meat, fish, poultry, fruits and vegetables; Carrier materials in active-component preparations (drugs, crop protection). In hygiene articles, superabsorbents act as a kind of liquid buffer that immediately stores simultaneously applied liquid insults, including fibers (cellulose fibers), which are intended to effectively channel body fluids towards the superabsorbent in the absorbent core. It is generally located in an absorbent core that includes other materials.

Current trends in diaper designs are to seek thinner structures with reduced cellulose fiber content and increased hydrogel content. The tendency to pursue thinner diaper structures has substantially changed the required performance profile of water swellable hydrophilic polymers over the years. It was initially only very high swelling that was of interest when starting to develop highly absorbent hydrogels, but then the ability of the superabsorbent to permeate and distribute the fluid was also determined to be of critical importance. It has been determined that conventional superabsorbents swell greatly at the surface when wetted with liquid such that liquid transport into the particles is substantially compromised or completely prevented. This property of superabsorbents is known as gel blocking. Higher amounts of polymer per unit area in sanitary articles should ensure that the swollen polymer does not cause the formation of a barrier layer for subsequent fluids. Products with good transport properties will ensure optimal utility of the entire hygiene article. This will prevent gel blocking and, in severe cases, will cause the hygiene article to leak. Thus, fluid permeation and distribution are critical for the initial absorption of body fluids.

For example, hydrogels with high gel strength in the swollen state have good transport properties. Insufficient strength gels may deform under applied pressure, for example due to the weight of the wearer's body weight of the hygiene article, blocking the pores of the SAP / cellulose fiber absorber to prevent continued absorption of the fluid. Improved gel strength is generally obtained through higher degrees of crosslinking, but this reduces the product's retention performance. An excellent way to improve gel strength is surface postcrosslinking. In this method, the dried superabsorbents having an average crosslinking density are subjected to a further crosslinking step. Surface postcrosslinking increases the crosslinking density in the sheath of the superabsorbent particles, whereby the absorbency under load is raised to a higher level. The absorbent capacity is reduced in the superabsorbent particle sheet while the core has an improved absorbent capacity (relative to the sheath) due to the presence of mobile polymer chains, so that the sheath structure improves fluid permeation without the occurrence of gel blocking effects. The total capacity of the superabsorbent is ideally preferred to be occupied with time grace and not simultaneously. Since hygiene products are generally soiled repeatedly with urine, the absorbent capacity of the superabsorbent should not be significantly depleted after the initial placement.

Highly swellable hydrophilic hydrogels are particularly suitable for polymers of (co) polymerized hydrophilic monomers, graft (co) polymers of one or more hydrophilic monomers on suitable grafting bases, crosslinked cellulose or starch esters, crosslinked carboxymethylcellulose, partial Polyalkylene oxides which are crosslinked with or natural products which swell in aqueous fluids, for example guar derivatives. Such hydrogels are used as absorbent aqueous solutions for the manufacture of diapers, tampons, sanitary napkins and other hygiene articles, as well as water-retaining agents in market gardening.

To improve performance properties, Rewet is generally surface or gel postcrosslinked, for example in diapers and AUL, which are highly swellable hydrophilic hydrogels. The postcrosslinking is known per se to the person skilled in the art and is preferably carried out on an aqueous gel or as a surface postcrosslinking of the polished and classified polymer particles.

EP # 238050 discloses double or triple acrylate or methacrylated addition polymers of ethylene oxide and / or propylene oxide with trimethylolpropane (as a possible internal crosslinking agent for superabsorbents).

Sartomer (Exton, Pennsylvania, USA) is for example trimethylolpropane triacrylate (SR 351), triple monoethoxylated trimethylolpropane triacrylate (SR 454) under the designation indicated. ), Triple diethoxylated trimethylolpropane triacrylate (SR 499), triple triethoxylated trimethylolpropane triacrylate (SR 502), triple pentaethoxylated trimethylolpropane triacrylate (SR 9035) and total 20 mmol mol ethoxylated trimethylolpropane triacrylate (SR 415) is sold. Propoxylated trimethylolpropane triacrylate is obtainable under the trade names SR 492 (3 × 1 PO per TMP) and CD 501 (3 × 2 PO per TMP).

WO 93/21237 discloses (meth) acrylates of alkoxylated polyvalent C ₂ -C ₁₀ hydrocarbons useful as crosslinking agents. The trimethylolpropane crosslinkers used correspond to SR 351, SR 454, SR 502, SR 9035 and SR 415. The crosslinker has 0, 3, 9, 15 or 20 EO units per TMP. WO 93/21237 describes advantageously having 3 × 2 to 7 EO units per TMP, in particular 3 × 4 to 6 EO units per TMP.

A disadvantage of these compounds is that expensive and inconvenient purification operations are required for at least partial removal of starting materials and by-products, and the crosslinkers used in the cited references have an acrylic acid content of less than 0.1% by weight.

Although ethoxylated trimethylolpropane tri (meth) acrylate is mentioned repeatedly in the patent literature as an internal crosslinking agent, only TMP derivatives commercially available from Sartomer are used, for example trimethylolpropane triethoxylate in WO # 98/47951. Triacrylates are used as high ethoxylated trimethylolpropane triacrylates (HeTMPTA) in WO # 01/41818 and SR # 9035 and SR-492 in WO # 01/56625.

Of this higher content of (meth) acrylic acid esters by acid-catalyzed esterification of (meth) acrylic acid with the corresponding alcohol in the presence of an inhibitor / inhibitor system and in the presence or absence of a solvent such as benzene, toluene or cyclohexane Manufacturing is common knowledge.

Since the formation of esters from (meth) acrylic acid and alcohols is known to be based on equilibrium reactions, esterifications and / or formed by using an excess of one starting material and / or to ensure that a commercial conversion can be obtained. It is common to remove the target ester from the equilibrium.

Therefore, in the production of higher content (meth) acrylic acid esters, it is common to remove the reaction water and to use excess (meth) acrylic acid.

US Pat. No. 4,187,383 describes a process for esterifying (meth) acrylic acid and organic polyols using an equivalent excess of 2: 1 to 3: 1 at a reaction temperature of 20 to 80 ° C.

The disadvantage of the process is that due to the low reaction temperature the reaction time is on the order of 35 hours and the excess acid in the reaction mixture is removed by neutralization followed by phase separation.

WO 2001/14438 (Derwent Abstract No. 2001-191644 / 19) and WO 2001/10920 Chemical Abstracts 134: 163502 have a ratio of (meth) acrylic acid and poly (3) to 50: 1 in the presence of an acid and a polymerization inhibitor. The process of esterifying an alkylene glycol monoalkyl ether and inactivating the acid catalyst followed by copolymerization of the residues of (meth) acrylic acid ester and (meth) acrylic acid at pH 1.5 to 3.5, and also the use of such residues as cement additives It is described.

A disadvantage of this process is that it is limited to polyalkylene glycol monoalkyl ethers and the catalyst must be inactivated and such copolymers cannot be used as crosslinkers for hydrogels because they have only one functional group.

It is an object of the present invention to provide further compounds which can be used as glass-radical crosslinkers for polymers, in particular superabsorbents, and to simplify the process for the preparation of materials useful as glass-radical crosslinkers for superabsorbents.

The inventors have found that this object is also achieved by the ester F of formula la.

Where

AO is independently EO, PO or BO in each case for each AO, where EO is O-CH ₂ -CH ₂ -and PO is independently in each case O-CH ₂ -CH (CH ₃ )-Or O-CH (CH ₃ ) -CH _2- , and BO is independently at each occurrence O-CH ₂ -CH (CH ₂ -CH ₃ )-or O-CH (CH ₂ -CH ₃ )- CH _2- ),

p ₁ + p ₂ + p ₃ is 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48 , 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73 , 74 or 75,

R 1, R 2 and R 3 are independently H or CH ₃ .

Preference is given to said ester F wherein at least one AO is EO and at least one further AO is PO or BO.

Especially preferred are those esters F wherein AO is EO in at least half of AO in all cases, preferably in at least 2/3 of AO in all cases.

Very particular preference is given to said ester F, in which only PO or BO, preferably only PO, are present with EO.

For p ₁ = m ₁ + n ₁ , p ₂ = m ₂ + n ₂ and p ₃ = m ₃ + n ₃ , preferably n ₁ + n ₂ + n ₃ is 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59 or 60 of n ₁ + n ₂ + n ₃ of EO and m ₁ + m ₂ + m ₃ is 4, 5, 6, 7, 8, 9, 10, 11, 12 or 13 of m ₁ + m Ester F mentioned above in which ₂ + m ₃ PO or BO are present. n represents the number of EO units per polyalkylene glycol chain and m represents the number of PO and / or BO units per polyalkylene glycol chain.

The various AO units may be present as blocks or mixed randomly.

Examples of esters with blocks are indicated below, but each PO unit may also be replaced by a BO unit.

This object is also achieved by providing ester F of formula Ib.

Where

EO is O-CH ₂ -CH _2- ,

PO in each occurrence is independently O-CH ₂ -CH (CH ₃ )-or O-CH (CH ₃ ) -CH _2- ,

n ₁ + n ₂ + n ₃ is 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48 , 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59 or 60,

m ₁ + m ₂ + m ₃ is 4, 5, 6, 7, 8, 9, 10, 11, 12 or 13,

R 1, R 2 and R 3 are independently H or CH ₃ .

This object is also achieved by providing ester F of formula

Where

EO is O-CH ₂ -CH _2- ,

PO in each occurrence is independently O-CH ₂ -CH (CH ₃ )-or O-CH (CH ₃ ) -CH _2- ,

n ₁ + n ₂ + n ₃ is 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48 , 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59 or 60,

m ₁ + m ₂ + m ₃ is 4, 5, 6, 7, 8, 9, 10, 11, 12 or 13,

R 1, R 2 and R 3 are independently H or CH ₃ .

AO, BO, EO or PO units are incorporated in such a way that polyethers are formed and no peroxides are formed.

Preferred are esters F as defined above wherein n ₁ , n ₂ and n ₃ are independently 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20.

Especially preferred are esters F as defined above wherein n ₁ , n ₂ and n ₃ are independently 9, 10 or 11.

Especially preferred are esters F as defined above wherein n ₁ , n ₂ and n ₃ are independently 15, 16, 17, 18, 19 or 20.

Preferred are esters F having the above meaning that n ₁ + n ₂ + n ₃ is 28, 29, 30, 31 or 32.

Preferred is ester F having the above meaning that n ₁ + n ₂ + n ₃ is 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59 or 60 .

Especially preferred are esters F having the above meaning wherein n ₁ + n ₂ + n ₃ is 30.

Especially preferred are esters F having the above meaning wherein n ₁ + n ₂ + n ₃ is 50.

Especially preferred are esters F having the above meaning that n ₁ = n ₂ = n ₃ = 10.

Especially preferred are esters F having the above meaning that n ₁ = n ₂ = 17 and n ₃ = 16.

Also preferred are esters F as defined above wherein m ₁ , m ₂ and m ₃ are independently 1, 2, 3, 4 or 5.

Especially preferred are esters F as defined above wherein m ₁ , m ₂ and m ₃ are independently 1, 2, or 3.

Especially preferred are esters F as defined above wherein m ₁ , m ₂ and m ₃ are independently 2, 3, 4 or 5.

Preferred are esters F having the above meaning that m ₁ + m ₂ + m ₃ is 4, 5 or 6.

Preferred are esters F having the above meaning that m ₁ + m ₂ + m ₃ is 7, 8, 9, 10, 11, 12 or 13.

Especially preferred are esters F having the above meaning wherein m ₁ + m ₂ + m ₃ is 5.

Especially preferred are esters F having the above meaning wherein m ₁ + m ₂ + m ₃ is 10.

Especially preferred are esters F having the above meaning that m _i = m _k = 3 and m _l = 4 (where i, k and l are all different and selected from the group consisting of 1, 2 and 3).

Especially preferred are esters F having the above meaning that m _i = m _k = 2 and m _l = 1, where i, k and l are all different and selected from the group consisting of 1, 2 and 3.

Very particular preference is given to ester F in which R 1, R 2 and R 3 are the same, in particular R 1, R 2 and R 3 are each H.

Especially preferred are esters F (formula Ib) comprising PO or BO, preferably PO in random distribution or as blocks ubiquitous in (meth) acrylic acid. Said preferred esters have an elevated freezing point and are liquid at room temperature (20 ° C.) and in some cases even at refrigerator temperature (5 ° C.), which allows for simplified and advantageous handling.

According to the invention, ester F of the above-mentioned formula having the meanings described above is used in the preparation of hydrogel-forming polymers capable of absorbing aqueous fluids, in particular as internal crosslinkers.

The inventors have

a) reacting an alkoxylated trimethylolpropane with (meth) acrylic acid to form ester F in the presence of at least one esterification catalyst C and at least one polymerization inhibitor D and optionally also a water-azeotropic solvent E,

b) optionally removing some or all of the water formed in step a) during and / or after step a) from the reaction mixture,

f) optionally neutralizing the reaction mixture,

h) if solvent E is used, optionally removing this solvent by distillation, and / or

i) stripping with an inert gas under reaction conditions

It was found that it is further achieved by a process for the preparation of ester F of alkoxylated trimethylolpropane and (meth) acrylic acid.

In a preferred embodiment,

A molar excess of (meth) acrylic acid: alkoxylated trimethylolpropane is at least 3.15: 1,

Optionally neutralized (meth) acrylic acid present in the reaction mixture after the last step remains substantially in the reaction mixture.

In the context of the present invention, (meth) acrylic acid is understood as methacrylic acid, acrylic acid, or a mixture of methacrylic acid and acrylic acid. Acrylic acid is preferred.

If the ester F is in its pure form, it can be purified by known separation methods.

The molar excess of (meth) acrylic acid: alkoxylated trimethylolpropane is at least 3.15: 1, preferably at least 3.3: 1, more preferably at least 3.75: 1, even more preferably at least 4.5: 1, especially 7.5: 1 That's it.

In a preferred embodiment, the (meth) acrylic acid is for example greater than 15: 1, preferably greater than 30: 1, more preferably greater than 60: 1, even more preferably greater than 150: 1, especially greater than 225: 1. Especially in excess of 300: 1.

The esterification products thus obtained can be used as radical crosslinkers in hydrogels without substantially further purification, especially without substantial removal of excess (meth) acrylic acid and esterification catalyst C.

Unless stated otherwise, crosslinking as used herein is understood to mean radical crosslinking (gel crosslinking; internal crosslinking; crosslinking with linear or slightly crosslinked polymers). The crosslinking can take place via free-radical or cationic polymerization mechanisms or other mechanisms, for example Michael addition, esterification or transesterification mechanisms, but is preferably carried out by free-radical polymerization.

Hydrogel-forming polymers capable of absorbing aqueous fluids are preferably capable of absorbing distilled water at or above its own weight, preferably 10 times its own weight, more preferably 20 times its own weight, preferably Preferably even up to 0.7 psi.

Alkoxylated trimethylolpropane useful for the purposes of the present invention has a structure as in Formula IIb or Formula IIc.

Where

EO, PO, n ₁ , n ₂ , n ₃ , m ₁ , m ₂ and m ₃ are as defined for the esters above, respectively.

The reaction of trimethylolpropane with alkylene oxides is well known to those skilled in the art. Possible methods of carrying out the reaction can be found in Houben-Weyl, Methoden der Organischen Chemie, 4th edition, 1979, Thieme Verlag Stuttgart, editor Heinz Kropf, volume 6 / 1a, part 1, pages 373 to 385.

An example of a process for the preparation of compounds of formula (IIb) is to first react trimethylolpropane with EO and then with PO.

This is achieved, for example, by putting about 77 g of trimethylolpropane together with 0.5 g KOH 45% in water as an initial charge and dehydrating the initial charge at 80 ° C. and reduced pressure (about 20 mbar). Thereafter, an appropriate amount of ethylene oxide is added at 145 to 155 ° C and reacted under elevated pressure at this temperature. The reaction is terminated when no further pressure change is observed. The reaction mixture is then stirred at 150 ° C. for an additional 30 minutes. Then, an appropriate amount of propylene oxide is added over an extended period of time at elevated pressure at 120-130 ° C. and reacted as well. After purging with inert gas and cooling to 60 ° C., the catalyst is separated by addition of sodium pyrophosphate and subsequent filtration.

An example of a method for preparing the compound of formula IIb is to first react trimethylolpropane with PO and then with EO.

This is achieved, for example, by putting about 77 g of trimethylolpropane together with 0.5 g KOH 45% in water as an initial charge and dehydrating the initial charge at 80 ° C. and reduced pressure (about 20 mbar). Thereafter, an appropriate amount of ethylene oxide is added at 120 to 130 ° C. and reacted under elevated pressure at this temperature. The reaction is terminated when no further pressure change is observed. The reaction mixture is then stirred at 120 ° C. for an additional 30 minutes. Then, an appropriate amount of propylene oxide is added over an extended period of time at elevated pressure at 145-155 ° C. and reacted as well. After purging with inert gas and cooling to 60 ° C., the catalyst is separated by addition of sodium pyrophosphate and subsequent filtration.

If intended to produce a random polymer, EO and PO are added simultaneously. For corresponding polymers intended to contain butylene oxide units, correspondingly BO is included as reactant.

The viscosity of the polyalcohols that can be used according to the invention does not require any specific requirements, they should be easily pumpable to about 80 ° C., and preferably their viscosity is less than 1000 mPas, preferably less than 800 mPas Most preferably less than 500 mPas.

The esterification catalyst C useful in the present invention is sulfuric acid, arylsulfonic acid or alkylsulfonic acid or mixtures thereof. Examples of arylsulfonic acids are benzenesulfonic acid, para-toluenesulfonic acid and dodecylbenzenesulfonic acid, and examples of alkylsulfonic acids are methanesulfonic acid, ethanesulfonic acid and trifluoromethanesulfonic acid. Similarly, strong acid ion exchangers or zeolites are useful as esterification catalysts. Preferred are sulfuric acid and ion exchangers.

Examples of polymerization inhibitors D useful in the present invention include, for example, phenols such as alkylphenols such as o-, m- or p-cresol (methylphenol), 2-tert-butyl-4-methylphenol , 6-tert-butyl-2,4-dimethylphenol, 2,6-di-tert-butyl-4-methylphenol, 2-tert-butylphenol, 4-tert-butylphenol, 2,4-di-tert -Butylphenol, 2-methyl-4-tert-butylphenol, 4-tert-butyl-2,6-dimethylphenol, or 2,2'-methylenebis (6-tert-butyl-4-methylphenol), 4 , 4'-oxydiphenol, 3,4- (methylenedioxy) phenol (cesamol), 3,4-dimethylphenol, hydroquinone, pyrocatechol (1,2-dihydroxybenzene), 2- (1 '-Methylcyclohex-1'-yl) -4,6-dimethylphenol, 2- or 4- (1'-phenyleth-1'-yl) phenol, 2-tert-butyl-6-methylphenol, 2 , 4,6-tris-tert-butylphenol, 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol, 4-tert-butylphenol, nonylphenol [11066-49-2] , Octylphenol [140-66-9], 2,6-dimethylphenol, bisphenol A, bisphenol F, bisphenol B, bisphenol C, bisphenol S, 3,3 ', 5,5'-tetrabromo-bisphenol A, 2,6-di-tert-butyl-p-cresol, Koresin® from BASF AG, Methyl 3,5-di-tert-butyl-4-hydroxybenzoate, 4-tert-butylpyrocatechol, 2-hydroxybenzyl alcohol, 2-methoxy-4-methylphenol, 2,3,6- Trimethylphenol, 2,4,5-trimethylphenol, 2,4,6-trimethylphenol, 2-isopropylphenol, 4-isopropylphenol, 6-isopropyl-m-cresol, n-octadecyl β- ( 3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3, 5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, 1,3,5-tris (3,5-di-tert-butyl-4- Hydroxybenzyl) isocyanurate, 1,3,5-tris (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxyethyl isocyanurate, 1,3,5-tris ( 2,6-dimethyl-3-hydroxy-4-tert-butylbenzyl) isocyanurate or pentaerythrate Lithol tetrakis [β- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,6-di-tert-butyl-4-dimethyl-aminomethylphenol, 6-sec- Butyl-2,4-dinitrophenol, Irganox® 565, 1141, 1192, 1222 and 1425, octadecyl 3- (3 ', from Ciba Spezialitaetenchemie 5'-di-tert-butyl-4'-hydroxyphenyl) propionate, hexadecyl 3- (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) -propionate, octyl 3- (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate, 3-thia-1,5-pentanediol bis [(3', 5'-di-tert-butyl -4'-hydroxyphenyl) propionate], 4,8-dioxa-1,11-undecanediol bis [(3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) prop Cypionate], 4,8-dioxa-1,11-undecandiol bis [(3'-tert-butyl-4'-hydroxy-5'-methylphenyl) propionate], 1,9-nonanediol Bis [(3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate], 1,7- Tandiamine bis [3- (3 ', 5, -di-tert-butyl-4'-hydroxyphenyl) propionamide], 1,1-methanediamine bis [3- (3', 5'-di-tert -Butyl-4'-hydroxyphenyl) propionamide], 3- (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionic acid hydrazide, 3- (3', 5'-di -Methyl-4'-hydroxyphenyl) propionic acid hydrazide, bis (3-tert-butyl-5-ethyl-2-hydroxyphen-1-yl) methane, bis (3,5-di-tert-butyl- 4-hydroxyphen-1-yl) methane, bis [3- (1'-methylcyclohex-1'-yl) -5-methyl-2-hydroxyphen-1-yl] methane, bis (3- tert-butyl-2-hydroxy-5-methylphen-1-yl) methane, 1,1-bis (5-tert-butyl-4-hydroxy-2-methylphen-1-yl) ethane, bis ( 5-tert-butyl-4-hydroxy-2-methylphen-1-yl) sulfide, bis (3-tert-butyl-2-hydroxy-5-methylphen-1-yl) sulfide, 1, 1-bis (3,4-dimethyl-2-hydroxyphen-1-yl) -2-methylpropane, 1,1-bis (5-tert-butyl-3-methyl-2-hydroxyphen-1- 1) butane, 1,3,5-tris- [1 '-(3 ", 5" -di-tert-butyl-4 "-hydroxy Pen-1 "-yl) meth-1'-yl] -2,4,6-trimethylbenzene, 1,1,4-tris (5'-tert-butyl-4'-hydroxy-2'-methylphene -1'-yl) butane, aminophenols such as para-aminophenol, nitrosophenols such as para-nitrosophenol, p-nitroso-o-cresol, alkoxyphenols such as 2- Methoxyphenol (guazacol, pyrocatechol monomethyl ether), 2-ethoxyphenol, 2-isopropoxyphenol, 4-methoxyphenol (hydroquinone monomethyl ether), mono- or di-tert-butyl- 4-methoxyphenol, 3,5-di-tert-butyl-4-hydroxyanisole, 3-hydroxy-4-methoxybenzyl alcohol, 2,5-dimethoxy-4-hydroxybenzyl alcohol Ringa alcohol), 4-hydroxy-3-methoxybenzaldehyde (vanillin), 4-hydroxy-3-ethoxybenzaldehyde (ethylvanillin), 3-hydroxy-4-methoxy-benzaldehyde (isovanillin), 1 -(4-hydroxy-3-methoxyphenyl) ethanone (acetobanillon), eugenol, dihydroeugenol, isoeugenol, Tocopherols such as α-, β-, γ-, δ- and ε-tocopherol, tocol, α-tocopherol hydroquinone, and also 2,3-dihydro-2,2-dimethyl-7-hydroxybenzofuran ( 2,2-dimethyl-7-hydroxycoumaran), quinones and hydroquinones, for example hydroquinone or hydroquinone monomethyl ether, 2,5-di-tert-butylhydroquinone, 2-methyl-p-hydroquinone, 2,3 -Dimethylhydroquinone, trimethylhydroquinone, 4-methylpyrocatechol, tert-butylhydroquinone, 3-methylpyrocatechol, benzoquinone, 2-methyl-p-hydroquinone, 2,3-dimethylhydroquinone, trimethylhydroquinone, 3-methyl Pyrocatechol, 4-methylpyrocatechol, tert-butylhydroquinone, 4-ethoxyphenol, 4-butoxyphenol, hydroquinone monobenzyl ether, p-phenoxyphenol, 2-methylhydroquinone, 2,5-di- tert-butylhydroquinone, tetramethyl-p-benzoquinone, diethyl 1,4-cyclohexanedione-2,5-dicarboxylate, phenyl-p-benzoquinone, 2,5-dimethyl- 3-benzyl-p-benzoquinone, 2-isopropyl-5-methyl-p-benzoquinone (thymoquinone), 2,6-diisopropyl-p-benzoquinone, 2,5-dimethyl-3-hydroxy -p-benzoquinone, 2,5-dihydroxy-p-benzoquinone, embelin, tetrahydroxy-p-benzoquinone, 2,5-dimethoxy-1,4-benzoquinone, 2-amino-5 -Methyl-p-benzoquinone, 2,5-bisphenylamino-1,4-benzoquinone, 5,8-dihydroxy-1,4-naphthoquinone, 2-anilino-1,4-naphtho Quinone, anthraquinone, N, N-dimethylindoaniline, N, N-diphenyl-p-benzoquinonediimine, 1,4-benzoquinone dioxime, coerulignone, 3,3'-di-tert -Butyl-5,5'-dimethyldiphenoquinone, p-rosolic acid (aurine), 2,6-di-tert-butyl-4-benzylidenebenzoquinone, 2,5-di-tert-amylhydroquinone, Nitroxide free radicals such as 4-hydroxy-2,2,6,6-tetramethylpiperidinyloxy free radicals, 4-oxo-2,2,6,6-tetramethylpiperidinyloxy glass Radical, 4-acetoxy-2,2,6,6-tetramethylpiperidinyloxy Li radical, 2,2,6,6-tetramethylpiperidinyloxy free radical, 4,4 ', 4 "-tris (2,2,6,6-tetramethylpiperidinyloxy) phosphite, 3- Oxo-2,2,5,5-tetramethylpyrrolidinyloxy free radical, 1-oxyl-2,2,6,6-tetramethyl-4-methoxypiperidine, 1-oxyl-2,2,6 , 6-tetramethyl-4-trimethylsilyloxypiperidine, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl 2-ethylhexanoate, 1-oxyl-2,2 , 6,6-tetramethylpiperidin-4-yl stearate, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl benzoate, 1-oxyl-2,2,6 , 6-tetramethylpiperidin-4-yl (4-tert-butyl) benzoate, bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) succinate, bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) adipate, bis (1-oxyl-2,2,6,6-tetramethyl-4-piperidinyl) 1 , 10-decanedioate, bis (1-oxyl-2,2,6,6-tetramethyl-4-piperidinyl) n-butylmalonate, bis (1-oxyl- 2,2,6,6-tetramethyl-4-piperidinyl) phthalate, bis (1-oxyl-2,2,6,6-tetramethyl-4-piperidinyl) isophthalate, bis (1-oxyl -2,2,6,6-tetramethyl-4-piperidinyl) terephthalate, bis (1-oxyl-2,2,6,6-tetramethyl-4-piperidinyl) hexahydroterephthalate, N , N'-bis (1-oxyl-2,2,6,6-tetramethyl-4-piperidinyl) adipamide, N- (1-oxyl-2,2,6,6-tetramethyl-4 -Piperidinyl) caprolactam, N- (1-oxyl-2,2,6,6-tetramethyl-4-piperidinyl) dodecylsuccinimide, 2,4,6-tris [N-butyl -N- (1-oxyl-2,2,6,6-tetramethyl-4-piperidinyl] triazine, N, N'-bis (1-oxyl-2,2,6,6-tetramethyl- 4-piperidinyl) -N, N'-bisporyl-1,6-diaminohexane, 4,4'-ethylenebis (1-oxyl-2,2,6,6-tetramethyl-3-pipe Lazinone), aromatic amines such as phenylenediamine, N, N-diphenylamine, N-nitrosodiphenylamine, nitrosodiethylaniline, N, N'-dialkyl-para-phenylenediamine Wherein the alkyl radicals may be the same or different and each independently contain 1 to 4 carbon atoms and may be straight or branched, for example N, N'-di-iso-butyl-p- Phenylenediamine, N, N'-di-iso-propyl-p-phenylenediamine, Irganox 5057, from Ciba Spezalilitathenehemi, N, N'-di-iso-butyl-p-phenylenediamine , N, N'-di-iso-propyl-p-phenylenediamine, p-phenylenediamine, N-phenyl-p-phenylenediamine, N, N'-diphenyl-p-phenylenediamine, N- Isopropyl-N-phenyl-p-phenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine (Kerobit® BPD from BASF AG), N-phenyl- N'-isopropyl-p-phenylenediamine (Vulkanox® 4010 from Bayer AG), N- (1,3-dimethyl-butyl) -N'-phenyl-p -Phenylenediamine, N-phenyl-2-naphthylamine, iminodibenzyl, N, N'-diphenylbenzidine, N-phenyltetraaniline, Acridon, 3-hydroxydiphenylamine, 4-hydroxydiphenylamine, hydroxylamine, for example N, N-diethylhydroxylamine, urea derivatives such as urea or thiourea, phosphorus compounds For example triphenylphosphine, triphenyl phosphite, hypophosphoric acid or triethyl phosphite, sulfur compounds such as diphenyl sulfide, phenothiazine or metal salts such as copper chloride, dithiocarbamic acid Copper, copper sulfate, copper salicylate, copper acetate, manganese chloride, manganese dithiocarbamate, manganese sulfate, manganese salicylate, manganese acetate, cesium chloride, cesium dithiocarbamate, cesium sulfate, cesium salicylate, cesium acetate, nickel chloride, dithi Orcabamate, nickel sulfate, nickel salicylate, nickel acetate, chromium chloride, dithiocarbamate chromium, chromium sulfate, chromium salicylate, chromium acetate, or mixtures thereof. Preferred are the phenols and quinones mentioned, particularly preferred are hydroquinone, hydroquinone monomethyl ether, 2-tert-butyl-4-methylphenol, 6-tert-butyl-2,4-dimethylphenol, 2,6-di-tert -Butyl-4-methylphenol, 2,4-di-tert-butylphenol, triphenyl phosphite, hypophosphoric acid, CuCl ₂ and guazacol, very particularly preferred are hydroquinone and hydroquinone monomethyl ether.

Especially preferred are hydroquinone monomethyl ethers, hydroquinones and alkylphenols, optionally in combination with triphenyl phosphite and / or hypophosphoric acid.

Very particular preference is given to α-tocopherol (vitamin E), β-tocopherol, γ-tocopherol or δ-tocopherol, optionally in combination with triphenyl phosphite and / or hypophosphoric acid.

Stabilization can be further maintained by the presence of an acid-containing gas, preferably air or a mixture of air and nitrogen (lean air).

Among the stabilizers cited, preferred are those which are aerobic, ie those which require the presence of oxygen to fully express their inhibitory effect.

Solvents E useful in the present invention are in particular solvents suitable for azeotropic removal of the reaction water, in particular aliphatic, cycloaliphatic and aromatic hydrocarbons or mixtures thereof.

Preferred are n-pentane, n-hexane, n-heptane, cyclohexane, methylcyclohexane, benzene, toluene or xylene. Especially preferred are cyclohexane, methylcyclohexane and toluene.

Esterification is a common method for preparing and / or post-treatment of polyhydric alcohols, for example those mentioned at the outset or DE-A 199 41 136, DE-A 38 43 843, DE-A 38 43 854, DE-A 199 37 911, DE-A 199 29 258, EP-A 331 845, EP 554 651 or US 4 187 383.

In general, esterification can be carried out as follows:

The esterification apparatus comprises a reactor having a stirred reactor, preferably a circulating evaporator, to which a distillation unit having a condenser and a phase separation vessel is added.

The reactor may for example be a reactor with jacketed heating and / or internal heating coils. Preference is given to using a reactor having an external heat exchanger and a natural or compulsory (ie through the use of a pump) circulator, more preferably a natural circulator in which the circulation is carried out without mechanical assistance.

It will be appreciated that the reaction can also be carried out in a reactor battery of a plurality of reaction zones, for example 2 to 4, preferably 2 or 3 reactors.

Suitable circulating evaporators are known to those skilled in the art and are described, for example, in R. Billet, Verdampfertechnik, HTB-Verlag, Bibliographisches Institut Mannheim, 1965, 53. Examples of circulating evaporators are tube heat exchangers, plate heat exchangers and the like.

It will be appreciated that the circulation system may also include a plurality of heat exchangers.

The distillation unit is of conventional design. This may suitably be a simple distillation unit with a splash guard or it may be a rectification column. Suitable column internals include in principle all conventional internals, for example trays, structured packing and / or dumped packing. Examples of preferred trays include bubble trays, sieve trays, valve trays, Thormann trays and / or dual-flow trays, and preferred dumping packings may be those of rings, coils, saddles or braids. .

Generally 5 to 20 theoretical plates are sufficient.

The condenser and separation vessel are of conventional design.

(Meth) acrylic acid and alkoxylated trimethylolpropane are generally used for esterification a) in molar excess as indicated above. The excess used may optionally be up to about 3000: 1.

Examples of useful esterification catalysts C include those cited above.

It is generally used in amounts of 0.1 to 5% by weight, preferably 0.5 to 5% by weight, more preferably 1 to 4% by weight and most preferably 2 to 4% by weight, based on the esterification mixture.

If desired, the esterification catalyst can be removed from the reaction mixture by an ion exchanger. The ion exchanger can be added directly to the reaction mixture and then filtered off or the reaction mixture can be passed through an ion filter bed.

Preferably, the esterification catalyst remains in the reaction mixture. However, when the catalyst is an ion exchanger, the ion exchanger is preferably removed, for example by filtration.

Stabilization can be further maintained by the presence of an oxygen-containing gas, preferably air or a mixture of air and nitrogen (lean air).

The oxygen-containing gas is preferably metered into the bottom region of the column and / or into the circulating evaporator and / or passed through and / or over the reaction mixture.

The polymerization inhibitor (mixture) D (as indicated above) is used in a total amount of 0.01 to 1% by weight, preferably 0.02 to 0.8% by weight, more preferably 0.05 to 0.5% by weight, based on the esterification mixture.

Polymerization inhibitors (mixtures) D can be used, for example, as aqueous solutions or as solutions in the reactants or products.

b) The reaction water formed in the course of the reaction during or after esterification a) can be distilled off, in which case the operation can be augmented by a solvent which forms an azeotrope with water.

In some cases, examples of the solvent E useful for azeotropic removal of the reaction water include the compounds cited above.

The esterification is preferably carried out in the presence of a solvent.

The amount of solvent used is 10 to 200% by weight, preferably 20 to 100% by weight, more preferably 30 to 100% by weight, based on the sum of the alkoxylated trimethylolpropane and (meth) acrylic acid.

However, for example, as described in column 2, lines 18 to 4, column 45 of DE-A1 38 43 854, there is no commutating agent but with the stabilizer mentioned above in reference to the cited reference. It can also be devised.

If the water in the reaction mixture is not removed through an azeotrope-forming solvent, it is an inert gas, preferably an oxygen-containing gas, more preferably air or lean air, as described, for example, in DE-A 38 43 843. Can be removed by stripping.

The reaction temperature for esterification a) is generally in the range from 40 to 160 ° C, preferably in the range from 60 to 140 ° C and more preferably in the range from 80 to 120 ° C. The temperature can be constant or elevated in the course of the reaction, and is preferably elevated in the course of the reaction. In this case, the final temperature of the esterification is 5-30 ° C. higher than the initial temperature. The temperature of esterification can be measured and controlled by varying the solvent concentration in the reaction mixture, as described in DE-A 199 41 136 and German Application File No. 100 63 175.4.

If a solvent is used, it can be distilled from the reaction mixture via a distillation unit added at the top of the reactor.

The distillate can be optionally removed or fed into the phase separation apparatus after condensation. As described in German Patent Application No. 100 63 175.4, the aqueous phase thus obtained is generally removed from the system, while the organic phase is fed into the distillation unit as reflux and / or passed directly into the reaction zone and / or ) Into the circulation evaporator.

When used as reflux, the organic phase can be used as described in DE-A 199 41 136 to control the temperature of esterification.

The esterification a) can be carried out without pressure, at superatmospheric pressure or at reduced pressure, preferably at atmospheric pressure.

The reaction time is generally in the range of 2 to 20 hours, preferably in the range of 4 to 15 hours, more preferably in the range of 7 to 12 hours.

The order of adding the individual reaction components is not essential to the present invention. All components may be introduced as mixed initial charge and then heated, or one or more components may be omitted from the initial charge or only partially included therein, and only the initial charge may be added after heating.

The (meth) acrylic acid that can be used is not limited to its composition and may include, for example, the following components:

(Meth) acrylic acid 90-99.9 wt% Acetic acid 0.05-3% by weight Propionic acid 0.01-1 wt% Diacrylic acid 0.01-5% by weight water 0.05-5% by weight Carbonyl 0.01-0.3 wt% Inhibitor 0.01-0.1 wt% Maleic acid or anhydride 0.001-0.5 wt%

The crude (meth) acrylic acid used is generally stabilized using 200 to 600 ppm phenothiazine or other stabilizer in an amount that allows for near stabilization. The carbonyl system herein refers to, for example, acetone and lower aldehydes such as formaldehyde, acetaldehyde, crotonaldehyde, acrolein, 2-furfural, 3-furfural and benzaldehyde.

Crude (meth) acrylic acid herein is obtained after absorption of the reaction gas of propane / propene / acrolein or isobutane / isobutene / methacrolein oxidation in the absorber and subsequent removal of the absorbent, or by fractional condensation of the reaction gas Refers to the (meth) acrylic acid mixture.

It is also clearly possible to use, for example, pure (meth) acrylic acid of the following purity:

(Meth) acrylic acid 99.7-99.99 wt% Acetic acid 50-1000 weight ppm Propionic acid 10-500 weight ppm Diacrylic acid 10-500 weight ppm water 50-1000 weight ppm Carbonyl 1-500 ppm by weight Inhibitor 1-300 ppm by weight Maleic acid or anhydride 1-200 weight ppm

The pure (meth) acrylic acid used is generally stabilized using 100 to 300 ppm of hydroquinone monomethyl ether or other storage stabilizer in an amount that allows almost stabilization.

Pure or purified (meth) acrylic acid generally refers to (meth) acrylic acid having a purity of at least 99.5% by weight and substantially free of aldehydes, other carbonyls, and high boiling components.

The distilled aqueous phase during esterification of the condensate removed through the added column (if present) may generally contain 0.1 to 10% by weight of (meth) acrylic acid, is separated off and removed from the system. The (meth) acrylic acid contained in the aqueous phase is preferably from 10 to 40 ° C. with any solvent used for the esterification, preferably esterification, for example cyclohexane and from 1: 5 to the aqueous phase versus extractant 30, preferably at a ratio of 1:10 to 20, and can be returned to esterification.

The circulation is carried out in or through or through the reaction mixture, for example based on the volume of the reaction mixture, with an inert gas, preferably an oxygen-containing gas, more preferably air, or a mixture of air and nitrogen (lean air) It can be further maintained by passing at a rate of 0.1 to 1, preferably 0.2 to 0.8, more preferably 0.3 to 0.7 m 3 / m 3 h.

The process of esterification a) can be monitored by monitoring the amount of water carried out and / or the decrease in the carboxylic acid concentration in the reactor.

For example, the reaction can be terminated as soon as 90%, preferably at least 95%, more preferably at least 98% of the theoretical expected amount of water is carried out by the solvent.

The end of the reaction can be detected, for example, from the fact that substantially no additional reaction water is removed via the co-agent. If (meth) acrylic acid is carried out with the reaction water, its fraction is determined, for example, by backtitrating an aliquot of the aqueous phase.

For example, it is not necessary to remove the reaction water when (meth) acrylic acid is used in a high stoichiometric excess, for example at least 4.5: 1, preferably at least 7.5: 1 and most preferably at least 15: 1. can do. In this case, a substantial part of the amount of water formed will be present in the reaction mixture. Reaction water determined to be volatile at the temperature used to remove the generated reaction water and above that temperature at which no measurement was performed is removed only during or after the reaction from the reaction mixture. For example, the resulting reaction water of at least 10% by weight is preferably at least 20% by weight, more preferably at least 30% by weight, even more preferably at least 40% by weight, most preferably at least 50% by weight. May be present in the mixture.

c) After the end of the esterification, the reaction mixture is typically cooled to 10-30 ° C. and adjusted to a solvent or any desired target ester concentration, which may be the same as any solvent used for azeotropic removal of water, if necessary. It can be cooled by the addition of different solvents.

In a further embodiment, the reaction is stopped with a suitable diluent G and the reactant is for example 10 to 90% by weight, preferably 20 to 80% by weight, more preferably 20 to 60, for example to reduce viscosity. It may be diluted to a concentration of weight percent, even more preferably 30 to 50 weight percent, most preferably about 40 weight percent.

It is important that a substantially homogeneous solution is formed after dilution.

It is preferably relatively shortly before use in the preparation of the hydrogel, for example up to 24 hours, preferably up to 20 hours, more preferably up to 12 hours, even more preferably up to 6 hours, most Preferably at least 3 hours before.

Diluent G is selected from the group consisting of water, a mixture of water with one or more organic solvents soluble in water in any proportion, and one or more monovalent or polyhydric alcohols such as methanol and a mixture of glycerol and water. The alcohol preferably has 1, 2 or 3 hydroxyl groups, preferably 1 to 10 and especially up to 4 carbon atoms. Primary and secondary alcohols are preferred.

Preferred alcohols are methanol, ethanol, isopropanol, ethylene glycol, 1,2-propanediol and 1,3-propanediol.

d) If desired, the reaction mixture is for example 0.1 to 50% by weight, preferably of activated carbon or metal oxide, for example alumina, silica, magnesium oxide, zirconium oxide, boron oxide or mixtures thereof. Decolorization by treatment at an amount of 0.5% to 25% by weight, more preferably 1 to 10% by weight, for example at 10 to 100 ° C, preferably at 20 to 80 ° C, more preferably at 30 to 60 ° C. Can be.

This can be done by adding a powder or granular bleaching agent to the reaction mixture and then filtering or passing the reaction mixture through a layer of bleaching agent in the form of any desired suitable molding.

Decolorization of the reaction mixture can be carried out at any desired stage of the workup process, for example at the stage of the crude reaction mixture or after any pre-washing, neutralization, washing or solvent removal.

The reaction mixture may further be treated with prewash e) and / or neutralization f) and / or postwash g), preferably only neutralization f). If necessary, the neutralization f) and the preliminary washing e) may be exchanged in order.

The (meth) acrylic acid, and / or catalyst C can be at least partially recovered from the aqueous phase of washings e) and g) and / or neutralizing f) by acidification and extraction with a solvent and can be reused.

In the case of pre- or post-washing e) or g), the reaction mixture is a washing liquid, for example water or 5-30% by weight, preferably 5-20% by weight, more preferably 5-15% by weight of sodium chloride , In a washing machine with potassium chloride, ammonium chloride, sodium sulfate or ammonium sulfate solution, preferably water or sodium chloride solution.

The ratio of reaction mixture to wash liquor is generally in the range from 1: 0.1 to 1: 1, preferably from 1: 0.2 to 1: 0.8, more preferably from 1: 0.3 to 1: 0.7.

Washing or neutralization can be carried out, for example, in stirred containers or other conventional equipment, for example columns or mixer-precipitator equipment.

In terms of processing engineering, any washing or neutralization of the process according to the invention is carried out by conventional extraction and washing methods and apparatus, for example Ullmann's Encyclopedia of Industrial Chemistry, 6th ed, 1999 Electronic Release, Chapter: Liquid-Liquid Extraction -Apparatus] can be used using those described. For example, single- or multi-stage, preferably single-stage extraction, and also for them can be selected in cocurrent or countercurrent mode, preferably countercurrent mode.

Preference is given to using sieve tray columns, aligned or randomly packed columns, stirred vessels or mixer-precipitator instruments and also columns with pulsed columns or rotating interiors.

Pre-cleaning e) preferably uses metal salts at any time, preferably copper or copper salts (combined) as inhibitors.

Post-washing g) may preferably be used to remove traces of bases or salts from the reaction mixture neutralized in f).

For neutralization f), the reaction mixture which is prewashed and can still contain a small amount of catalyst and a major amount of excess (meth) acrylic acid is added with a solution of 5 to 15% by weight of a solution of sodium chloride, potassium chloride, ammonium chloride or ammonium sulfate. Bases which may be used, for example alkali or alkaline earth metal oxides, hydroxides, carbonates or bicarbonates, preferably aqueous sodium hydroxide solutions, aqueous potassium hydroxide solutions, sodium bicarbonate, sodium carbonate, potassium bicarbonate, calcium hydroxide, lime oil, ammonia gas, 5 to 25% by weight, preferably 5 to 20% by weight, more preferably 5 to 15% by weight of aqueous ammonia or potassium carbonate, if desired, more preferably aqueous sodium hydroxide solution or aqueous sodium hydroxide- It can be neutralized with sodium chloride solution. The degree of neutralization is preferably in the range of 5 to 60 mol%, preferably 10 to 40 mol%, more preferably 20 to 30 mol%, based on the acid-functional monomer. This neutralization can be carried out before and / or during the polymerization, preferably before the polymerization.

The base is added in such a way that the temperature of the device does not rise above 60 ° C., or is preferably in the range of 20 to 35 ° C., and a pH of 4 to 13. The neutralization heat is preferably removed by cooling the vessel by internal cooling coils or through jacket cooling.

The ratio of reaction mixture to neutralization liquid is generally in the range from 1: 0.1 to 1: 1, preferably from 1: 0.2 to 1: 0.8, more preferably from 1: 0.3 to 1: 0.7.

Regarding the apparatus, the above description applies.

h) If a solvent is present in the reaction mixture, the solvent can be removed substantially by distillation. Preferably any solvent present is removed from the reaction mixture after washing and / or neutralization, although in some cases this may be done before washing or neutralization.

In this case, the reaction mixture is mixed with a storage stabilizer, preferably an amount of hydroquinone monomethyl ether, after removal of the solvent, from 100 to 500 ppm, preferably from 200 to 500 ppm, more preferably from 200 to 400 ppm. To this target ester (residue).

Distillation of the main amount of solvent is carried out under reduced pressure, for example in a stirred tank equipped with a heating jacket and / or an internal heating coil, for example 20 to 700 mbar, preferably 30 to 500 mbar, more preferably 50 To 150 mbar and 40 to 80 ° C.

It will be appreciated that distillation may be accomplished in falling film or thin film evaporators. In this case, the reaction mixture is preferably recycled two or more times at reduced pressure through the apparatus, for example at 20 to 700 mbar, preferably at 30 to 500 mbar, more preferably at 50 to 150 mbar and at 40 to 80 ° C. .

Inert gases, preferably oxygen-containing gases, more preferably air, or mixtures of air and nitrogen (lean air) are preferably for example 0.1 to 1, preferably based on the volume of the reaction mixture into the distillation apparatus. Preferably from 0.2 to 0.8, more preferably from 0.3 to 0.7 m 3 / m 3 / h.

The residual solvent content of the residue is generally less than 5% by weight, preferably 0.5 to 5% by weight, more preferably 1 to 3% by weight after distillation.

The solvent removed is condensed and is preferably reused.

If desired, solvent stripping operation i) can be carried out in addition to or instead of distillation.

In this case, the target ester, which still contains a small amount of solvent, is heated to 50-90 ° C., preferably 80-90 ° C., and the residual amount of solvent is removed with a suitable gas in a suitable instrument. In some cases, an environment is created in which a vacuum can be applied to the support.

Examples of useful instruments include columns of conventional design containing conventional internals such as trays, dumped packings or structured packings, preferably dumped packings. Useful column interiors include in principle all conventional interiors such as trays, alignment packing and / or random packing. Examples of preferred trays include bubble trays, sieve trays, valve trays, torman trays and / or dual-flow trays, although preferred dumped packings include rings, coils, saddles, Raschig, intos ( Packing of Intos or Pall rings, barrels or Intalox saddles, Top-Pak etc. or braids.

It is also possible to use falling film, thin film or wipe-film evaporators herein, such as Luwa, Rotafilm or Sambay evaporators, which for example use demisters. To prevent the splash.

Examples of useful gases are gases which are inert under stripping conditions, preferably oxygen-containing gases, more preferably air, or mixtures of air and nitrogen (lean air) or water vapor, in particular those which are preheated to 50 to 100 ° C. Included.

The gas stripping rate is for example in the range of 5 to 20, more preferably 10 to 20 and most preferably 10 to 15 m 3 / m 3 h, based on the volume of the reaction mixture.

If desired, the ester is treated at any stage of the workup process, preferably after filtration / neutralization after washing / neutralization, and solvent removal may be carried out so that optionally precipitated traces of salt and any decolorant can be removed. Can be.

In an conceivable embodiment, the esterification of alkoxylated trimethylolpropane with (meth) acrylic acid a) in the presence of at least one esterification catalyst C and at least one polymerization inhibitor D is carried out without a solvent capable of forming an azeotrope with water. As indicated above, the molar excess is at least 15: 1.

In a preferred embodiment, the excess (meth) acrylic acid is preferably substantially not removed, ie from the reaction mixture determined to be volatile above the temperature used to remove the carboxylic acid and above that temperature not measured. Distillation, rectification, extraction (eg washing), absorption (eg passing through activated carbon or ion exchangers) and / or scavenging of carboxylic acids using chemical steps such as epoxide Only the fraction of (meth) acrylic acid is removed.

The extent to which the (meth) acrylic acid in the reaction mixture is removed therefrom is preferably 75% by weight or less, more preferably 50% by weight or less, even more preferably based on (meth) acrylic acid in the reaction mixture after the reaction is completed. 25% by weight or less, in particular 10% by weight or less, most preferably 5% by weight or less. In a particularly preferred embodiment, by omission of step b) only the fraction of reaction water and (meth) acrylic acid can be removed from the reaction mixture determined to be volatile at the temperature used. This may preferably be blocked by substantially complete condensation.

In addition, the esterification catalyst C used is likewise substantially left in the reaction mixture.

The DIN EN 3682 acid value of the reaction mixture thus obtained is preferably in the range of 25 mg or more KOH / g, more preferably 25 to 80, most preferably 25 to 50 mg KOH / g in the reaction mixture.

Any pre- or post-wash e) or g) is preferably omitted, but may be discernible only with filtration step j).

The reaction mixture can then be diluted in step c), in which case it is converted to the hydrogel preferably in 6 hours, more preferably in 3 hours. The reaction mixture may preferably be neutralized in step f).

The order of steps c), j) and f) is arbitrary.

The present invention further

At least one ester F obtainable by one of the esterification processes described above,

(Meth) acrylic acid and

-Diluent G

It provides a composition comprising a.

The composition of the present invention

Esterification catalyst C in protonated or unprotonated form,

Polymerization inhibitor D and also

Any solvent E when used for esterification

It may further include.

The composition may be neutralized and have the pH recited above under f).

When the composition is neutralized, at least some of the (meth) acrylic acid has been converted to its water soluble alkali metal, alkaline earth metal or ammonium salt.

Preferred compositions

0.1 to 40% by weight, more preferably 0.5 to 20% by weight, even more preferably 1 to 10% by weight, in particular 2 to 5% by weight, specifically 2 to 4% by weight of ester F in the fraction,

0.5 to 99.9% by weight, more preferably 0.5 to 50% by weight, even more preferably 1 to 25% by weight, in particular 2 to 15% by weight, specifically 3 to 5% by weight of monomer M,

0 to 10% by weight, more preferably 0.02 to 5% by weight, even more preferably 0.05 to 2.5% by weight, in particular 0.1 to 1% by weight of esterification catalyst C,

0 to 5% by weight, more preferably 0.01 to 1.0% by weight, even more preferably 0.02 to 0.75% by weight, in particular 0.05 to 0.5% by weight, specifically 0.075 to 0.25% by weight of polymerization inhibitor D,

0 to 10% by weight, more preferably 0 to 5% by weight, even more preferably 0.05 to 1.5% by weight, in particular 0.1 to 0.5% by weight of solvent E, provided that the total is always 100% by weight, and Also

Any diluent G in the amount added to be 100% by weight

It includes.

The reaction mixture obtainable by the above process and the composition according to the invention

Radical crosslinkers of water-absorbing hydrogels,

Starting materials for the preparation of polymer dispersions,

Starting materials for the preparation of polyacrylates (except hydrogels),

-Paint raw materials or

-Cement additives

Use as can be found.

Compositions according to the invention which are particularly useful as radical crosslinking agents of water-absorbing hydrogels are at least 0.5% by weight, preferably at least 1% by weight, more preferably at least 2% by weight, even more preferably at 25 ° C. in distilled water. It has a solubility of at least weight percent, particularly preferably at least 10 weight percent, even more preferably at least 20 weight percent, in particular at least 30 weight percent.

k) a reaction mixture from esterification comprising a post-treatment step of esterification in practice, for example a reaction mixture from f), in which case the reaction mixture from b) or b) is omitted. In this case the reaction mixture from a) may optionally be mixed with further monoethylenically unsaturated compounds N having no acid groups but copolymerizable with the hydrophilic monomer M, followed by one or more radical initiators K and optionally one or more grafting bases L Water-absorbing hydrogels can be prepared by polymerization in the presence of.

It may be desirable to carry out l) to postcrosslink the reaction mixture of k).

Examples of useful hydrophilic monomers M for preparing such highly swellable hydrophilic hydrogels k) are, for example, addition polymerizable acids, such as acrylic acid, methacrylic acid, etacrylic acid, α-chloroacrylic acid, crotonic acid, maleic acid, Maleic anhydride, vinylsulfonic acid, vinylphosphonic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, glutamic acid, aconitic acid, allylsulfonic acid, sulfoethyl acrylate, sulfoethyl methacrylic acid Latex, sulfopropyl acrylate, sulfopropyl methacrylate, 2-hydroxy-3-acryloyloxypropylsulfonic acid, 2-hydroxy-3-methacryloyloxypropylsulfonic acid, allylphosphonic acid, styrenesulfonic acid, 2 -Acrylamido-2-methylpropanesulfonic acid, 2-acrylamido-2-methylpropanephosphonic acid and also their amides, hydroxyalkyl esters and amino- or amonio-containing S Ter and amides. The monomers may be used alone or mixed with each other. There is also a water-soluble N-vinylamide and also diallyldimethylammonium chloride. Preferred hydrophilic monomers are compounds of formula (V)

Where

R ³ is hydrogen, methyl or ethyl,

R ⁴ is COOR ⁶ , a sulfonyl group, a phosphonyl group, a (C ₁ -C ₄ ) -alkanol-esterified phosphonyl group of formula VI:

R ⁵ is hydrogen, methyl, ethyl or a carboxyl group,

R ⁶ is hydrogen, amino or hydroxy- (C ₁ -C ₄ ) -alkyl,

R ⁷ is a sulfonyl group, a phosphonyl group or a carboxyl group.

Examples of (C ₁ -C ₄ ) -alkanols are methanol, ethanol, n-propanol and n-butanol.

Particularly preferred hydrophilic monomers are acrylic acid and methacrylic acid, in particular acrylic acid.

In order to optimize the properties, it can be appreciated to use additional monoethylenically unsaturated compounds N which do not have acid groups but are copolymerizable with monomers having acid groups. Such compounds include, for example, amides and nitriles of monoethylenically unsaturated carboxylic acids, for example acrylamide, methacrylamide and N-vinylformamide, N-vinylacetamide, N-methylvinylacetamide, acrylonitrile And methacrylonitrile. Examples of further suitable compounds include vinyl esters of saturated C ₁ -to C ₄ -carboxylic acids, for example vinyl formate, vinyl acetate or vinyl propionate, alkyl vinyl ethers having two or more carbon atoms in the alkyl group, For example ethyl vinyl ether or butyl vinyl ether, esters of monoethylenically unsaturated C ₃ -to C ₆ -carboxylic acids, for example monovalent C ₁ to C ₁₈ -alcohols and acrylic acid, methacrylic acid or maleic acid Esters, monoesters of maleic acid, for example methyl hydrogen maleate, N-vinyllactams such as N-vinylpyrrolidone or N-vinylcaprolactam, alkoxylated monovalent saturated alcohols such as Acrylic acid and methacrylic acid esters of alcohols having from 10 to 25 carbon atoms, wherein they are from 2 to 200 mol of ethylene oxide and / or propylene oxide per mol of alcohol Reacted), and also monoacrylic acid esters and monomethacrylic acid esters of polyethylene glycol or polypropylene glycol, wherein the molar mass (M _n ) of the polyalkylene glycols is 2000 or less). Further suitable monomers are styrene and alkyl-substituted styrenes such as ethyl styrene or tert-butyl styrene.

The monomers having no acid groups can also be used in any ratio in mixtures with other monomers, for example mixtures of vinyl acetate and 2-hydroxyethyl acrylate. Said monomers having no acid groups are added to the reaction mixture in an amount ranging from 0 to 50% by weight, preferably less than 20% by weight.

The crosslinked (co) polymers are preferably converted into their alkali metal or ammonium salts before and after the polymerization, and the acid-functionality of which the monoethylenically unsaturated monomer having no acid groups is from 0 to 40% by weight based on its total weight. It consists of a monoethylenically unsaturated monomer.

The preparation, testing and use of (meth) acrylic acid (co) polymers, polyacrylic acids and superabsorbers have been widely described before and are well known (see, for example, "Modern Superabsorbent Polymer Technology", FL Buchholz and AT Graham, Wiley-VCH, 1998 or Markus Frank "Superabsorbents" in Ullmann's Handbuch der technischen Chemie, Volume 35, 2003).

Preference is given to such hydrogels obtained by cross-linking addition polymerization or copolymerization of acid-functional monoethylenically unsaturated monomers M or salts thereof.

The polymers obtainable are noteworthy for the improved saponification index (VSI).

In the postcrosslinking process, the starting polymer is treated with a postcrosslinker, preferably postcrosslinked during or after the treatment, dried by rising temperature, and the crosslinking agent is preferably contained in an inert solvent. Inert solvents are solvents that do not substantially react with the starting polymer or postcrosslinker. Preference is given to such solvents which do not chemically react with the starting polymer or postcrosslinker to a degree of at least 90%, preferably at least 95%, more preferably at least 99%, in particular at least 99.5%.

The postcrosslinking l) and drying m) are preferably carried out at 30 to 250 ° C, in particular at 50 to 200 ° C, most preferably at 100 to 180 ° C. The surface postcrosslinking solution is preferably added by spraying the polymer in a suitable spray mixer. After spraying, the polymer powder is heat dried and the crosslinking reaction can be carried out before and during the drying operation. Preference is given to spraying or mixing and drying the crosslinker solution in the reaction mixer, for example a Loedige mixer, a BEPEX mixer, a NAUTA mixer, a SHUGGI mixer or a PROCESSALL. It is also possible to use fluidized bed dryers.

The drying operation can be carried out in the mixer itself by heating the shell or blowing hot air. Downstream dryers are also suitable, for example shelf dryers, rotary tube ovens or heatable screws. However, for example, azeotropic distillation may be used as the drying technique. The preferred residence time at this temperature in the reaction mixer or dryer is less than 60 minutes, more preferably less than 30 minutes.

Preference is given to the above process wherein the starting polymer is polymeric acrylic acid or polyacrylate, especially polymeric acrylic acid or polyacrylate obtained by free-radical polymerization using a polyfunctional ethylenically unsaturated radical crosslinker.

Preference is given to those processes wherein the composition containing the radical crosslinking agent, ie ester F, and diluent G is used in a proportion of 0.1 to 20% by weight, in particular 0.5 to 10% by weight, based on the mass of the starting polymer.

The radical crosslinking agent is added in an amount of 0.01 to 5.0% by weight, preferably 0.02 to 3.0% by weight, more preferably 0.03 to 2.5% by weight, especially 0.05 to 1.0% by weight, specifically 0.1 to 0.75% by weight, based on the starting polymer. This method used is preferred.

The invention also relates to the above-mentioned for use in hygiene articles, packaging materials and nonwovens, and also for the production of crosslinked or thermally crosslinkable polymers, in particular paints and varnishes, by one of the aforementioned methods. Polymers for use in the prepared compositions.

The highly swellable hydrophilic hydrogels (starting polymers) used are in particular polymers of (co) polymerized hydrophilic monomers M, graft (co) polymers of at least one hydrophilic monomer M on a suitable grafting base L, crosslinked cellulose or starch Natural products, such as guar derivatives, which can swell in ether or aqueous fluids. Such hydrogels are known to those skilled in the art and are described, for example, in US-4 286 082, DE-C-27 06 135, US-4 340 706, DE-C-37 13 601, DE-C-28 40 010, DE -A-43 44 548, DE-A-40 20 780, DE-A-40 15 085, DE-A-39 17 846, DE-A-38 07 289, DE-A-35 33 337, DE-A -35 03 458, DE-A-42 44 548, DE-A-42 19 607, DE-A-40 21 847, DE-A-38 31 261, DE-A-35 11 086, DE-A-31 18 172, DE-A-30 28 043, DE-A-44 18 881, EP-A-0 801 483, EP-A-0 455 985, EP-A-0 467 073, EP-A-0 312 952 , EP-A-0 205 874, EP-A-0 499 774, DE-A-26 12 846, DE-A-40 20 780, EP-A-0 20 5674, US-5 145 906, EP-A -0 530 438, EP-A-0 670 073, US-4 057 521, US-4 062 817, US-4 525 527, US-4 295 987, US-5 011 892, US-4 076 663 or US -4 931 497. Highly swellable hydrogels from the manufacturing operations described in WO 01/38402 and also highly swellable inorganic / organic hybrid hydrogels described in DE 198 54 575 are particularly suitable. The contents of the aforementioned patent documents, in particular the hydrogels obtained by the process, are incorporated herein by reference.

Suitable grafting bases L for hydrophilic hydrogels obtainable by graft copolymerization of olefinically unsaturated acids may be of natural or synthetic origin. Examples are starch, cellulose, cellulose derivatives and also other polysaccharides and oligosaccharides, polyalkylene oxides, in particular polyethylene oxides and polypropylene oxides, and also hydrophilic polyesters.

Water-absorbing polymers are obtainable by free-radical graft copolymerization of acrylic acid or acrylate onto a water soluble polymer matrix. Non-limiting examples of suitable water soluble polymer matrices are, for example, polysaccharides such as alginate, polyvinyl alcohol, and starch. Graft copolymerization uses a polyfunctional ethylenically unsaturated radical crosslinking agent for the purposes of the present invention.

The water-absorbing polymer may be an organic / inorganic hybrid polymer formed from polymeric acrylic acid or polyacrylate on the one hand and silicates, aluminates or aluminosilicates on the other hand. More particularly, the polymeric acrylic acid or polyacrylates used are obtained by free-radical polymerization using polyfunctional ethylenically unsaturated radical crosslinkers and can be formed using water soluble silicates or soluble aluminates or mixtures thereof.

Preferred hydrogels are especially polyacrylates, polymethacrylates and also US-4 931 497, US-5 011 892 and US-5 041 496 graft polymers. Very particularly preferred hydrogels are the kneader polymers described in WO 01/38402 and the polyacrylate-based organic / inorganic hybrid hydrogels described in DE 198 545 75.

Materials prepared according to the invention, useful as radical crosslinking agents in hydrogels, can be used alone or in combination with other crosslinking agents, for example internal or surface crosslinking agents, for example:

Suitable further crosslinking agents are in particular methylenebisacrylamide, methylenebismethacrylamide, esters of unsaturated mono- or polycarboxylic acids with polyols, for example diacrylates or triacrylates, for example butanediol diacrylate, butanediol Dimethacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, and also trimethylolpropane triacrylate and allyl compounds such as allyl (meth) acrylate, triallyl cyanurate, diallyl maleate , Polyallyl esters, tetraallyloxyethanes, triallylamines, tetraallylethylenediamines, allyl esters of phosphoric acid and also vinylphosphonic acid derivatives as described, for example, in EP-A-0 343 427. However, hydrogels prepared by acidic homopolymerization of acrylic acid with polyallyl ether as further crosslinking agent are particularly preferred for use in the process of the invention. Suitable crosslinkers are pentaerythritol triallyl ether, pentaerythritol tetraallyl ether, polyethylene glycol diallyl ether, monoethylene glycol diallyl ether, glycerol diallyl ether, glycerol triallyl ether, polyallyl ether and also based on sorbitol Their ethoxylated variants. Examples of particularly preferred crosslinkers further include ethoxylated derivatives of polyethylene glycol diacrylate, trimethylolpropane triacrylate, for example Sartomer SR 9035, and also ethoxylated derivatives of glycerol diacrylate and glycerol triacrylate. Can be mentioned. It is also obviously possible to use mixtures of such crosslinkers.

Especially preferred are crosslinker combinations in which further crosslinkers can be dispersed in the crosslinkers of the invention. Examples of such crosslinker combinations are the crosslinkers of the present invention used with di- or tripropylene glycol diacrylates and propoxylated glyceryl triacrylates.

Very particular preference is given to hydrogels prepared using ester F prepared according to the invention as radical crosslinking agent.

The water-absorbing polymer is preferably polymeric acrylic acid or polyacrylate. Such water-absorbing polymers can be prepared by methods known from the literature. Polymers containing crosslinking comonomers (0.001 to 10 mol%) are preferred, but polymers obtained by free-radical polymerization and in which multifunctional ethylenically unsaturated radical crosslinkers are used are very particularly preferred.

Highly swellable hydrophilic hydrogels can be prepared by known addition polymerization methods per se. It is preferable that addition polymerization is performed in aqueous solution as gel polymerization. As mentioned above, a diluted, preferably aqueous, more preferably 15 to 50% by weight aqueous solution of one or more hydrophilic monomers, and optionally preferably without mechanical mixing (Trommsdorff- Norrish effect) Makromol. Chem. 1, 169 (1947), including a suitable grafting base L polymerized in the presence of a free-radical initiator. The polymerization reaction can be carried out at 0 ° C. to 150 ° C., preferably at 10 ° C. to 100 ° C. and at atmospheric pressure, superatmospheric pressure or reduced pressure. Typically, the polymerization may also be carried out under a protective gas atmosphere, preferably nitrogen. The addition polymerization can be carried out with high energy electromagnetic radiation or conventional chemical polymerization initiators K, for example organic peroxides such as benzoyl peroxide, tert-butyl hydroperoxide, methyl ethyl ketone peroxide, cumene hydroperoxide, azo compounds, For example azobisisobutyronitrile and also inorganic peroxy compounds such as (NH ₄ ) ₂ S ₂ O ₈ , K ₂ S ₂ O ₈ or H ₂ O ₂ .

If desired, they may contain aliphatic and aromatic sulfinic acids such as benzenesulfinic acid and toluene sulfinic acid or derivatives thereof such as the Mannich adducts of sulfinic acid, aldehyde and amino compounds ( Redox system (as described in DE-C-1 301 566) or a reducing agent, for example ascorbic acid, sodium bisulfite and iron (II) sulfate. The performance properties of the polymer can be further improved by postheating the polymer gel for several hours at a temperature in the range from 50 ° C. to 130 ° C., preferably from 70 ° C. to 100 ° C.

The gel obtained is neutralized to a degree of from 0 to 100 mol%, preferably from 25 to 100 mol%, more preferably from 50 to 85 mol%, based on the monomers used, for this purpose conventional neutralizing agents, preferably alkali metals. Hydroxides, alkali metal oxides or corresponding alkali metal carbonates, more preferably sodium hydroxide, sodium carbonate and sodium bicarbonate can be used.

Neutralization is typically accomplished by mixing the neutralizing agent into the gel as an aqueous solution or preferably as a solid. In this case, the gel is mechanically subdivided, for example by a meat grinder, sprayed, scattered or poured with a neutralizing agent and mixed carefully. The gel mass obtained can then be repeatedly passed through a meat grinder for homogenization. The neutralized gel mass can then be dried using a belt or dryer until the residual moisture content is preferably below 10% by weight, in particular below 5% by weight.

Such addition polymerization may be carried out by any other method described in the literature. More particularly, the neutralization of acrylic acid may be carried out before the polymerization as described above in step f). The polymerization can then be carried out continuously or batchwise in a conventional belt reactor or dough reactor. Where the polymerization is carried out in a belt reactor, particular preference is given to initiation by electromagnetic radiation, preferably by UV radiation or by another redox initiator system. Very particular preference is also given to a combination of the two methods of initiation (simultaneous electromagnetic radiation and chemical redox initiator system).

n) Then, the dried hydrogel is pulverized and sieved, in which case it is customary to use a roll mill, a pin mill or a vibration mill for grinding. The preferred particle size of the sieved hydrogel is preferably in the range of 45 to 1000 μm, more preferably 45 to 850 μm, even more preferably 200 to 850 μm and most preferably 300 to 850 μm. Another more particularly preferred range is 150 to 850 μm, especially 150 to 700 μm. These ranges preferably comprise 80% by weight of particles, in particular 90% by weight of particles. The size distribution can be determined using established laser methods.

The present invention further provides a crosslinked hydrogel containing at least one hydrophilic monomer M in copolymerized form and crosslinked using ester F of alkoxylated trimethylolpropane with (meth) acrylic acid. The ester can be prepared in the manner according to the invention or in the manner of the prior art, preferably in the manner according to the invention.

Useful esters F include the compounds described above.

The CRC value [g / g] of the hydrogel-forming polymer according to the invention can be measured by the method shown in the detailed description, preferably greater than 15, in particular 16, 18, 20, 22, 24 or more, more preferred. Preferably 25, in particular 26, 27, 28, 29, even more preferably 30, 31, 32, 33, 34, 35, 36, 37 or more.

The AUL 0.7 psi value [g / g] of the hydrogel-forming polymer according to the invention can be measured by the method shown in the detailed description, preferably greater than 8, in particular 9, 10, 11, 12, 13, 14 or more, more preferably 15, especially 16, 17, 18, 19 or more, even more preferably more than 20, especially 21, 22, 23, 24, 25, 26, 27, 28 or more.

The AUL 0.5 psi value [g / g] of the hydrogel-forming polymer according to the invention can be measured by the method shown in the detailed description, preferably greater than 8, in particular 9, 10, 11, 12, 13, 14 or more, more preferably 15, especially 16, 17, 18, 19 or more, even more preferably more than 20, especially 21, 22, 23, 24, 25, 26, 27, 28 or more.

The saponification index VSI of the hydrogel-forming polymers according to the invention can be measured by the method shown in the detailed description, preferably below 10, in particular below 9.5, 9 or 8.5, more preferably below 8, especially 7.5 , 7, 6.5, 6, 5.5 or less, even more preferably less than 5, in particular 4.5, 4, 3.5 or less.

The residual crosslinker content of the hydrogel-forming polymer according to the invention can be measured by the method shown in the detailed description, preferably less than 10 ppm, in particular up to 9.5 ppm, 9 ppm or 8.5 ppm, more preferably 8 less than ppm, in particular 7.5 ppm, 7 ppm, 6.5 ppm, 6 ppm, 5.5 ppm or less, even more preferably less than 5 ppm, especially 4.5 ppm, 4 ppm, 3.5 ppm or less.

Application and use of the hydrogel-forming polymer according to the invention

The present invention further

(P) Liquid-penetrating Top Sheet

(Q) Liquid-impermeable backsheet

(R) from 10 to 100% by weight of hydrogel-forming polymer according to the invention, from 0 to 90% by weight of hydrophilic fibrous material, preferably from 20 to 100% by weight of hydrogel-forming polymer according to the invention from 0 to 100% 80% by weight, more preferably 30 to 100% by weight of the hydrogel-forming polymer according to the invention, 0 to 70% by weight of the hydrophilic fibrous material, even more preferably 40 to 100% by weight of the hydrogel-forming polymer according to the invention %, 0 to 60% by weight hydrophilic fiber material, even more preferably 50 to 100% by weight hydrogel-forming polymer according to the invention, 0 to 50% by weight hydrophilic fiber material, particularly preferably hydrogel according to the invention -60 to 100% by weight of forming polymer, 0 to 40% by weight of hydrophilic fiber material, particularly preferably 70 to 100% by weight of hydrogel-forming polymer according to the invention, hydrophilic fiber 0-30% by weight, very preferably 80-100% by weight of hydrogel-forming polymer according to the invention, 0-20% by weight of hydrophilic fibrous material, most preferably 90-90% hydrogel-forming polymer according to the invention A core located between (P) and (Q), comprising 100% by weight, 0-10% by weight hydrophilic fiber material,

(S) optionally, a tissue layer located directly above and below the core (R), and

(T) optionally a capture layer located between (P) and (R)

It relates to the use of said hydrogel-forming polymer in a hygiene article comprising a.

The percentage is 11 to 12%, 12%, 13%, 14%, 15%, 16%, 17%, 18% by weight of the hydrogel-forming polymer according to the invention when it is 10 to 100% by weight. %, 19% to up to 100% in each case and all intermediate% (eg 12.2%) are possible, correspondingly from 0% to 89%, 88%, 87% of each hydrophilic fibrous material It should be understood that weight percent, 86 weight percent, 85 weight percent, 83 weight percent, 82 weight percent, 81 weight percent and intermediate percentages (eg, 87.8%) are possible. If additional material is present in the core, the percentage of polymer and fiber decreases accordingly. The same applies for the preferred range, for example 81% by weight, 82% by weight, 83% by weight, 84% by weight, 85% by weight, 86% by weight, extremely preferred for the hydrogel-forming polymer according to the invention. 19 wt%, 18 wt%, 17 wt%, 16 wt%, 15 wt%, 14 wt%, 13 wt%, 12 wt% for the weight percent, 88 wt%, 89 wt% and correspondingly to the fiber material %, 11% by weight. As such, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29% by weight of the hydrogel-forming polymer according to the present invention. May be present in the preferred range of 100% by weight to 30% by weight, 31% by weight, 32% by weight, 33% by weight, 34% by weight, 35% by weight, 36% by weight for the hydrogel-forming polymer according to the invention %, 37%, 38%, 39% to 100% by weight, 40% by weight, 41% by weight, 42% by weight, more preferred ranges for the hydrogel-forming polymer according to the invention. It can be present in weight percent, 44 weight percent, 45 weight percent, 46 weight percent, 47 weight percent, 48 weight percent, 49 weight percent to 100 weight percent, and more preferred ranges for the hydrogel-forming polymer according to the invention Phosphorus 50 wt%, 51 wt%, 52 wt%, 53 wt%, 54 wt%, 55 wt%, 56 wt%, 57 60%, 61%, 62%, 63% by weight, which may be present in the range of 60% by weight, 58% by weight, 59% by weight to 100% by weight and even more preferred ranges for the hydrogel-forming polymer according to the invention. , 70% by weight, 65% by weight, 66% by weight, 67% by weight, 68% by weight, 69% by weight to 100% by weight, which is a particularly preferred range for the hydrogel-forming polymers according to the invention. %, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79% to 100% by weight, according to the present invention. The most preferred ranges for the hydrogel-forming polymer are 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% To 100% by weight.

Hygiene articles for the purposes of the present invention include infant diapers as well as adult incontinence pads and incontinence briefs.

Liquid-penetrating topsheets P are layers that directly contact the wearer's skin. Its materials include conventional synthetic or processed fibers or films of natural fibers such as polyester, polyolefins, rayon or cotton. In the case of nonwovens, the fibers are generally bonded together by a binder such as polyacrylate. Preferred materials are polyesters, rayon and blends thereof, polyethylene and polypropylene. Examples of liquid-penetrating layers are disclosed in WO 99/57355 A1, EP 102 388 3 A2.

The liquid-impermeable layer (Q) is generally a polyethylene or polypropylene sheet.

The core (R) comprises hydrophilic fibrous materials as well as hydrogel-forming polymers according to the invention. Hydrophilic means that the aqueous fluid diffuses quickly into the fibers. The fiber material is typically polyester, such as cellulose, modified cellulose, rayon, polyethylene terephthalate. Cellulose fibers such as pulp are particularly preferred. The fibers generally have a diameter of 1 to 200 μm and preferably 10 to 100 μm and a minimum of 1 mm in length.

Diaper structures and forms are commonly known and are described, for example, in WO 95/26 209 page 66 line 34 to page 69 line 11, DE 196 04 601 A1, EP-A-0 316 518 and EP-A. -0 202 127. Diapers and other sanitary articles are also generally in WO 00/65084, in particular in the sixth to fifteenth aspect, in WO 00/65348, in particular in the fourth to seventeenth aspect, in WO 00/35502, in particular in the third to ninth aspect. , DE 19737434, WO 98/8439. Feminine care hygiene products are disclosed in the following references. Subject material hydrogel-forming polymers capable of absorbing aqueous fluids can be used therein. Female care reference: WO 95/24173: absorbent article for odor control, WO 91/11977: body fluid odor control, EP 389023: absorbent cleansing article, WO 94/25077: odor control substance, WO 97/01317: absorbent hygiene article , WO 99/18905, EP 834297, US 5,762,644, US 5,895,381, WO 98/57609, WO 2000/065083, WO 2000/069485, WO 2000/069484, WO 2000/069481, US 6,123,693, EP 1104666, WO 2001/024755 , WO 2001/000115, EP 105373, WO 2001/041692, EP 1074233. Tampons are disclosed in the following references: WO 98/48753, WO 98/41179, WO 97/09022, WO 98/46182, WO 98 / 46181, WO 2001/043679, WO 2001/043680, WO 2000/061052, EP 1108408, WO 2001/033962, DE 200020662, WO 2001/001910, WO 2001/001908, WO 2001/001909, WO 2001/001906, WO 2001 / 001905, WO 2001/24729. Incontinence articles are disclosed in the following references: Disposable absorbent articles for individuals with incontinence: EP 311344 Specification Pages 3-9; Disposable absorbent articles: EP 850623; Absorbent articles: WO 95/26207; Absorbent articles: EP 894502; Dry fiber structures: EP 850 616; WO 98/22063; WO 97/49365; EP 903134; EP 887060; EP 887059; EP 887058; EP 887057; EP 887056; EP 931530; WO 99/25284; WO 98/48753. Feminine care articles and incontinence articles are described in the following references: Physiological Devices: WO 93/22998, pages 26-33; Absorption sources for body fluids: WO 95/26209 specification pages 36-69; Disposable absorbent articles: WO 98/20916 specification pages 13-24; Improved composite absorbent structure: EP 306262 specification pages 3-14; Fecal absorbent articles: WO 99/45973. These references and references therein are expressly incorporated herein.

The hydrogel-forming polymers according to the invention are very useful as absorbents for water and aqueous fluids, advantageously making them useful as water retaining agents, filter aids and in particular as absorbent components of hygiene products such as diapers, tampons or sanitary napkins. Can be used.

Incorporation and fixation of highly swellable hydrogels according to the invention

In addition to the highly swellable hydrogels, the absorbent compositions of the present invention are structures that comprise highly swellable hydrogels and secure them there. Any structure can provide a highly swellable hydrogel and is suitable for incorporation into an absorbent layer. Many such compositions are already known and described in detail in the literature. Structures for attaching highly swellable hydrogels can be made of, for example, fiber matrices (air webs, wet webs) or synthetic polymer fibers (meltblown webs, spunbonded forms) of cellulose fiber mixtures ( spunbonded) webs) or else fiber blends of cellulose fibers and synthetic fibers. Possible fiber materials are described in the following chapters. Such pneumatic web processes are for example disclosed in WO 98/28478. Moreover, open-celled foams and the like can be used to attach highly swellable hydrogels.

Alternatively, the structure may be the result of fusing two separate layers to form one or more multiple chambers containing highly swellable hydrogels. The chamber system is described in detail in EP 0 615 736 A1, page 7, line 26 below.

In this case, at least one of the two layers should be water permeable. The second layer can be water permeable or water impermeable. The layer material used may be a tissue made of tissue or other fabric, closed or open-celled foam, perforated film, elastomer or fibrous material. If the absorbent composition consists of a layered structure, the layered material should have a pore structure, the diameter of which should be small enough to hold highly swellable hydrogel particles. The above example of the structure of the absorbent composition also includes a laminate of two or more layers with a high swellable hydrogel attached and immobilized therebetween.

In general, the hydrogel particles can be immobilized within the absorbent core to improve dry and wet integrity. Dry and wet preservation demonstrates the ability to attach highly swellable hydrogels to the absorbent composition in such a way that they withstand external forces in the wet as well as the dry state and do not dislodge or spill the highly swellable polymer. The forces mentioned are in particular the mechanical stresses generated when the hygiene article is worn and moved up or down, or in other words the medium pressure applied to the hygiene article especially in incontinence. As regards fixation, those skilled in the art are aware of a number of possibilities. By way of example, fixing by heat treatment, adhesives, thermoplastics, addition of bonding materials is disclosed in WO 95/26 209 page 37 line 36 to page 41 line 14. The cited parts are thus part of the present invention. Methods for enhancing wet strength will also be found in WO 2000/36216 A1.

Moreover, the absorbent composition may comprise a base material, such as a polymer film, having immobilized highly swellable hydrogel particles thereon. Fixation can be performed on one side as well as on two sides. The base material may be water permeable or water impermeable.

The structure of the absorbent composition comprises 10 to 100 weight percent, preferably 20 to 100 weight percent, more preferably 30 to 100 weight percent of the highly swellable hydrogel, based on the total weight of the structure and the total weight of the highly swellable hydrogel. % By weight, even more preferably 40 to 100% by weight, even more preferably 50 to 100% by weight, particularly preferably 60 to 100% by weight, even more preferably 70 to 100% by weight, very preferably 80 to 100% by weight and most preferably 90 to 100% by weight.

Fiber material of absorbent composition

The structure of the present absorbent composition according to the present invention is based on various fiber materials and can be used as a fiber network or matrix. The present invention includes natural fibers (modified or unmodified) fibers as well as synthetic fibers.

A detailed overview of examples of fibers that can be used in the present invention are disclosed in WO 95/26 209 page 28 line 9 to page 36 line 8. The cited parts are thus part of the present invention.

Examples of cellulose include cellulose fibers commonly used in absorbent articles, such as fluff pulp and cellulose of the cotton type. The materials (soft or hardwood), product processing such as chemical pulp, semichemical pulp, chemical thermophysical pulp (CTMP) and bleaching processing are not particularly limited. For example, natural cellulose fibers such as cotton, flax, silk, wool, jute, ethylcellulose and cellulose acetate can be used.

Suitable synthetic fibers include polyvinyl chloride, polyvinyl fluoride, polytetrafluoroethylene, polyvinylidene chloride, polyacrylic compounds such as ORLON®, polyvinyl acetate, polyethyl vinyl acetate, It can be prepared from soluble or insoluble polyvinyl alcohol. Examples of synthetic fibers include thermoplastic polyolefin fibers such as polyethylene fibers (PULPEX®), polypropylene fibers and polyethylene-polypropylene bicomponent fibers, polyester fibers such as polyethylene terephthalate fibers (dark DACRON® or KODEL®), copolyester, polyvinyl acetate, polyethyl vinyl acetate, polyvinyl chloride, polyvinylidene chloride, polyacrylic, polyamide, copolyamide , Polystyrene and copolymers of said polymers and also bicomponent fibers consisting of polyethylene terephthalate-polyethylene-isophthalate copolymers, polyethyl vinyl acetate / polypropylene, polyethylene / polyester, polypropylene / polyester, copolyester / poly Ester, Polyamide Fiber (Nylon), Polyurethane Oils, polystyrene fibers and polyacrylonitrile fibers, polyolefin fibers, polyester fibers and bicomponent fibers thereof are preferred, furthermore because of their excellent dimensional stability due to fluid absorption, Preference is given to heat-bonded bicomponent fibers consisting of polyolefins.

The synthetic fibers mentioned are preferably used in combination with thermoplastic fibers. In the heat treatment process, the latter moves to some extent into the matrix of fibrous material present to make up the bond site and refresh the cured element upon cooling. The addition of thermoplastic fibers also means that the dimensions of the pores increase after heat treatment. This makes it possible to continuously increase the proportion of thermoplastic fibers in the topsheet direction by the continuous addition of thermoplastic fibers during formation of the absorbent layer, which causes a similar continuous increase in pore size. The thermoplastic fibers may be formed from a plurality of thermoplastic polymers having a melting point of less than 190 ° C., preferably 75 ° C. to 175 ° C. These temperatures are so low that no damage to cellulose occurs.

The length and diameter of the synthetic fibers are not particularly limited, and in general, any fiber of 1 to 200 mm in length and 0.1 to 100 denier (1 g per 9000 m) in diameter can be preferably used. Preferred thermoplastic fibers are 3 to 50 mm in length and particularly preferred thermoplastic fibers are 6 to 12 mm in length. Preferred diameters for the thermoplastic fibers range from 1.4 to 10 decitex, particularly preferred ranges from 1.7 to 3.3 decitex (1 g per 10,000 m). The type of fiber can vary; Examples include woven, narrow cylinders, cut / chopped twisted yarns, staple fibers and continuous filament fibers.

The fibers in the absorbent compositions of the present invention may be hydrophilic and / or hydrophobic. As defined by Robert F. Gould in the 1964 American Chemical Society publication "Contact angle, wettability and adhesion", the contact angle between the liquid and the fiber (or fiber surface) is less than 90 ° or the liquid is spontaneously on the same surface. The fiber in the case of the tendency to spread is called hydrophilicity. Two processes generally coexist. Conversely, the fibers are called hydrophobic if they form contact angles greater than 90 ° and no spreading is observed.

Preference is given to using hydrophilic fibrous materials. Particular preference is given to using the most hydrophilic fibrous material in the area surrounding the weakly hydrophilic and highly swellable hydrogel on the body surface. In the manufacturing process, layers with different hydrophilicity are used to create a gradient, the path through which the fluid penetrates into the hydrogel (which ultimately absorbs the fluid).

Examples of hydrophilic fibers suitable for use in the absorbent compositions of the present invention include, for example, cellulose fibers, modified cellulose fibers, rayon, polyester fibers, such as polyethylene terephthalate (Dacron®), and hydrophilic Nylon (HYDROFIL®). Suitable hydrophilic fibers are also thermoplastic fibers obtained by hydrophilic hydrophobic fibers, for example from polyolefins (for example polyethylene or polypropylene, polyamides, Polystyrene, polyurethane, etc.) can be obtained by treatment with a surfactant or silica, however, cellulosic fibers are preferred due to cost problems and ease of handling.

Highly swellable hydrogel particles are embedded in the fibrous material. This is achieved by using a combination of hydrogel materials and the fibers together to form an absorbent layer in the form of a matrix, whereby a highly swellable hydrogel is formed into a fiber mixture layer, where the hydrogel ultimately attaches or deposits layers. Fixed)).

The fluid-capturing and fluid-distributing fiber matrix can be made from synthetic fibers or cellulose fibers or a mixture of synthetic fibers and cellulosic fibers, where the mixing ratio can vary from (100 to 0) synthetic fibers: (0 to 100) cellulosic fibers. Yes). The cellulosic fibers used can furthermore be chemically strengthened to increase the dimensional stability of the hygiene article.

Chemical reinforcement of cellulosic fibers can be provided in different ways. The first method of providing fiber reinforcement is to add a suitable coating to the fiber material. Examples of such additives include, for example, polyamide-epichlorohydrin coatings [Kymene® 557 H, Hercoles, Inc. Wilmington, Delaware, Wilmington, Delaware] , Polyacrylamide coatings (Parez® 631 NC, disclosed in US-A-3,556,932 or from American Cyanamid Co., Stamford, CT, Stamford, Connecticut). Commercially available products), melamine-formaldehyde coatings and polyethyleneimine coatings.

Cellulosic fibers can also be chemically strengthened by chemical reactions. For example, suitable crosslinking materials can be added to crosslink in the fiber. Suitable crosslinking materials are C ₂ -C ₈ having an acid functional-crosslinking monomer used in the polyester include, carboxylic acids that are not limited thereto - dialdehyde, C ₂ -C ₈ -, especially C ₂ -C ₉ mono-aldehydes and It is a typical substance. Particular substances from this class are, for example, glutaraldehyde, glyoxal, glyoxalic acid, formaldehyde and citric acid. These materials react between two or more hydroxyl groups in any cellulose chain or between two adjacent cellulose chains in any cellulose fiber. The crosslinking results in reinforcement of the fibers, which provides dimensional stability to the fibers as a result of this treatment. In addition to their hydrophilicity, these fibers exhibit a uniform combination of reinforcement and elasticity. This physical property makes it possible to maintain the capillary structure even under simultaneous contact with the fluid and the compressive force and to prevent premature collapse.

Chemically crosslinked cellulose fibers are known and are disclosed in WO 91/11162, US 3,224,926, US 3,440,135, US 3,932,209, US 4,035,147, US 4,822,453, US 4,888,093, US 4,898,642 and US 5,137,537. Chemical crosslinking provides reinforcement to the fiber material, which is ultimately reflected in improved dimensional stability for sanitary articles. The individual layers are joined to one another by methods known to those skilled in the art, for example by intermelting by addition of heat treatments, heat-melt adhesives, latex binders and the like.

Process for preparing absorbent composition

The absorbent composition consists of a structure containing a highly swellable hydrogel and a highly swellable hydrogel present in or immobilized thereon.

Examples of methods for obtaining an absorbent composition consisting of a base material having, for example, a high swellable hydrogel attached on one or two sides are known and included in the present invention, but are not limited thereto.

For example, a fiber material blend of synthetic fibers (a) and cellulose (b) embedded in a highly swellable hydrogel (c), wherein the blend ratio is (100 to 0) synthetic fibers: (0 to 100) cellulose fibers Examples of methods for obtaining an absorbent composition consisting of (1) (a), (b) and (c) are mixed together once and equally, (2) (a) and (b) To a mixture of (c), (3) a mixture of (b) and (c) with (a), (4) a mixture of (a) and (c) with (b) Method (5), (b) and (c) are mixed and (a) is continuously metered, (6) (a) and (c) are mixed, and (b) is continuously metered. And (7) (b) and (c) are mixed, and (a) is individually weighed and added. Among these examples, methods (1) and (5) are preferred. The instrument used in this method is not particularly limited, and any conventional instrument known to those skilled in the art can be used.

The absorbent composition obtained by this method can optionally be subjected to heat treatment to obtain an absorbent layer having excellent dimensional stability in the moisture state. The heat treatment process is not particularly limited. Examples include heat treatment by hot air or infrared supply. The temperature of the heat treatment is in the range of 60 ° C to 230 ° C, preferably 100 ° C to 200 ° C, particularly preferably 100 ° C to 180 ° C.

The heat treatment duration depends on the type of synthetic fiber, its amount and the rate of hygiene article production. In general, the heat treatment duration is in the range of 0.5 seconds to 3 minutes, preferably 1 second to 1 minute.

In general, absorbent compositions include, for example, liquid-permeable topsheets and liquid-impermeable backsheets. In addition, the end and attachment tabs are attached to finish the sanitary article. The materials and types of permeable topsheets and impermeable backsheets and the materials and types of fold and attachment tabs are known to those skilled in the art and are not particularly limited. Examples thereof can be found in WO 95/26 209.

The invention is advantageous in that it does not need to be purified after the formation of the ester F, which is useful as a crosslinking agent, and in particular because (meth) acrylic acid, preferably acrylic acid, for hydrogel formation is generally a monomer.

Experimental part

Unless otherwise indicated, parts per million and percentages are parts by weight.

The following examples illustrate the method of the present invention.

Claims (30)

Ester F of Formula (Ia) <Formula Ia> Where AO is independently EO, PO or BO in each case for each AO, where EO is O-CH ₂ -CH ₂ -and PO is independently in each case O-CH ₂ -CH (CH ₃ )-Or O-CH (CH ₃ ) -CH _2- , and BO is independently at each occurrence O-CH ₂ -CH (CH ₂ -CH ₃ )-or O-CH (CH ₂ -CH ₃ )- CH _2- ), p ₁ + p ₂ + p ₃ is 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48 , 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73 , 74 or 75, R 1, R 2 and R 3 are independently H or CH ₃ . The ester F of claim 1, wherein at least one AO is EO and at least one additional AO is PO or BO. The ester F according to claim 1 or 2, wherein AO is EO at least half of AO in all cases. Ester F according to any one of claims 1 to 3, wherein only PO or BO is present with EO. The method according to any one of claims 1 to 4, wherein n ₁ + n ₂ + n ₃ is 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41 N ₁ + n ₂ + n ₃ EO, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59 or 60 an ester F with m ₁ + m ₂ + m ₃ PO or BO, wherein m ₁ + m ₂ + m ₃ is 4, 5, 6, 7, 8, 9, 10, 11, 12 or 13. Ester F of Formula (Ib) <Formula Ib> Where EO is O-CH ₂ -CH _2- , PO in each occurrence is independently O-CH ₂ -CH (CH ₃ )-or O-CH (CH ₃ ) -CH _2- , n ₁ + n ₂ + n ₃ is 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48 , 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59 or 60, m ₁ + m ₂ + m ₃ is 4, 5, 6, 7, 8, 9, 10, 11, 12 or 13, R 1, R 2 and R 3 are independently H or CH ₃ . Ester F of Formula (Ic) <Formula Ic> Where EO is O-CH ₂ -CH _2- , PO in each occurrence is independently O-CH ₂ -CH (CH ₃ )-or O-CH (CH ₃ ) -CH _2- , n ₁ + n ₂ + n ₃ is 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48 , 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59 or 60, m ₁ + m ₂ + m ₃ is 4, 5, 6, 7, 8, 9, 10, 11, 12 or 13, R 1, R 2 and R 3 are independently H or CH ₃ . 8. Ester according to any one of claims 1 to 7, wherein n ₁ , n ₂ and n ₃ are independently 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20. F. The ester F of claim ₁ , wherein m ₁ , m ₂ and m ₃ are independently 1, 2, 3, 4 or 5. 10. The ester F of claim 1, wherein m ₁ + m ₂ + m ₃ is 5 or 10. 11. The ester F according to any one of claims 1 to 10, wherein n ₁ + n ₂ + n ₃ is 30 or 50. The ester F according to any one of claims 1 to 11 wherein R 1, R 2 and R 3 are the same, preferably H. a) reacting an alkoxylated trimethylolpropane with (meth) acrylic acid to form ester F in the presence of at least one esterification catalyst C and at least one polymerization inhibitor D and optionally also a water-azeotropic solvent E, b) optionally removing some or all of the water formed in step a) during and / or after step a) from the reaction mixture, f) optionally neutralizing the reaction mixture, h) if solvent E is used, optionally removing this solvent by distillation, and / or i) stripping with an inert gas under reaction conditions A process for preparing ester F according to any one of claims 1 to 12 of alkoxylated trimethylolpropane of formula (IIa), (IIb) or (IIc) and (meth) acrylic acid, comprising: <Formula IIa> <Formula IIb> <Formula IIc> Where AO, EO, PO, p ₁ , p ₂ , p ₃ , n ₁ , n ₂ , n ₃ , m ₁ , m ₂ and m ₃ are the same as defined in any one of claims 1 to 12, respectively. . The method of claim 13, A molar excess of (meth) acrylic acid: alkoxylated trimethylolpropane is at least 3.15: 1, The optionally neutralized (meth) acrylic acid present in the reaction mixture after the last step remains substantially in the reaction mixture. The process according to claim 13 or 14, wherein the (meth) acrylic acid removed from the reaction mixture containing ester F obtained after the last step is 75% by weight or less. The process according to any one of claims 13 to 15, wherein the acid value of DIN EN # 3682 of the reaction mixture containing ester F obtained after the last step is at least 25 mg KOH / g. The process according to any one of claims 13 to 16, wherein the (meth) acrylic acid content of the reaction mixture containing ester F obtained after the last step is at least 0.5% by weight. The process according to claim 13, wherein the molar ratio of (meth) acrylic acid to alkoxylated trimethylolpropane in reaction a) is at least 15: 1. k) Ester F according to any one of claims 1 to 12 in the presence of at least one free-radical inhibitor K and optionally at least one grafting base L, with (meth) acrylic acid and optionally further monoethylene Polymerizing with the systemically unsaturated compound N and optionally also with at least one further copolymerizable hydrophilic monomer M, l) optionally postcrosslinking the reaction mixture obtained from step k), m) drying the reaction mixture obtained from step k) or l), and n) optionally grinding and / or sieving the reaction mixture obtained from step k), l) or m) Comprising a method for producing a crosslinked hydrogel. Steps a) to i) according to any one of claims 13 to 18 and further k) in the presence of at least one free-radical inhibitor K and optionally at least one grafting base L, the reaction mixture from one of steps a) to i) optionally comprises further monoethylenically unsaturated compounds N and optionally Also polymerizing with at least one further copolymerizable hydrophilic monomer M, l) optionally postcrosslinking the reaction mixture obtained from step k), m) drying the reaction mixture obtained from step k) or l), and n) optionally grinding and / or sieving the reaction mixture obtained from step k), l) or m) Comprising a method for producing a crosslinked hydrogel. Polymer obtainable according to the process according to claim 19. Crosslinked hydrogel containing at least one hydrophilic monomer M in copolymerized form crosslinked with ester F according to claim 1. 19. A crosslinked hydrogel containing at least one hydrophilic monomer M in copolymerized form crosslinked with a reaction mixture containing ester F, obtainable according to the method according to any one of claims 13-18. Use of the polymer according to any of claims 21 to 23 in hygiene articles, packaging materials and nonwovens. At least one ester F according to any one of claims 1 to 12 and from 0.1 to 40% by weight of (meth) acrylic acid, 0.5-99.9% by weight of one or more hydrophilic monomers M, 0 to 10% by weight of at least one esterification catalyst C, At least one polymerization inhibitor D 0-5% by weight, and Solvent E 0 to 10% by weight Wherein the total is always 100% by weight. The method of claim 25, Further comprising a diluent G added to be 100% by weight. From a composition according to claim 25, or further l) postcrosslinking the reaction mixture optionally obtained, m) drying the reaction mixture obtainable directly or from step l), and n) crosslinked hydrogel, optionally obtainable directly from or by grinding and / or sieving the reaction mixture obtainable from step l) or m). Free-radical crosslinkers of water-absorbent hydrogels, Starting materials for the preparation of polymer dispersions, Starting materials for the preparation of polyacrylates, -Paint raw materials, or Use of a reaction mixture obtainable according to the method according to any one of claims 13 to 17 or as a cement additive or a composition according to claims 25 or 26. The crosslinked hydrogel according to any of claims 21 to 23 and 27, wherein the residual crosslinker content is less than 10 ppm, preferably less than 8 ppm and more preferably less than 5 ppm. Use of ester F according to any one of claims 1 to 12 for the preparation of hydrogel-forming polymers capable of absorbing aqueous fluids.