WO1992000336A1

WO1992000336A1 - Use of aqueous polyurethane dispersions in leather dressing

Info

Publication number: WO1992000336A1
Application number: PCT/EP1991/001132
Authority: WO
Inventors: Michael Marschner; Werner Krause; Horst Schulz; Gerhard Kaindl
Original assignee: Henkel Kommanditgesellschaft Auf Aktien
Priority date: 1990-06-27
Filing date: 1991-06-19
Publication date: 1992-01-09
Also published as: DE4020456A1

Abstract

The invention concerns the use, in the dressing of leather, of an aqueous polyurethane dispersion containing 100 parts by weight of di- and/or polyisocyanates, 61 to 450 parts by weight (relative to the isocyanate content) of castor oil and/or epoxidized fatty-acid esters ring-opened with C1-8? alkyl alcohols.

Description

Use of aqueous polyurethane dispersions in the leather trimmings

The invention relates to the use of an aqueous polyurethane dispersion which, based on 100 parts by weight of di- and / or polyisocyanates, contains 61 to 450 parts by weight of castor oil and / or epoxidized fatty acid esters ring-opened with C 8 alkyl alcohols in the leather finishing.

Leather finishing is the protective layer that is applied to the leather that has been dried after tanning and oiling in order to protect it against moisture, dirt and damage (Ull anns Encyclopedia of Technical Chemistry, 4th edition, volume 16, pages 159-163, Verlag Chemie Weinheim, 1978). The finishing film must adhere firmly to the leather and satisfy extremely high bending and expansion requirements during further processing and during later use. Furthermore, the surface of the

Dressing film must be hard enough to ensure adequate resistance to damage from dry and wet rubbing, bumping and scratching. So that the dressing film can meet these different requirements, it is applied in several thin layers of different dressing liquors, in particular priming and finishing liquors, with respective intermediate drying and, if necessary, intermediate hangers and embossing. In many cases, the finishing liquors contain polyurethanes, thermoplastic polyacrylates and / or butadiene copolymers as film-forming substances. DE 37 02 615 describes polyurethane dispersions as coating and finishing agents for leather whose polyurethane solids, based on 100 parts by weight of isocyanate component, 6 to 60 parts by weight of castor oil, alkoxylated castor oil and / or epoxidized triglycerides which are ring-opened with C 8 alkyl alcohols are optionally alkoxylated. Leather that has been finished with these polyurethane dispersions have good fastness properties.

It has now been found that the fastness properties achieved with the polyurethane dispersions known from DE 37 02 615 are significantly improved if a polyurethane dispersion is used whose polyurethane solids, based on 100 parts by weight of isocyanate component, 61 to 450 parts by weight of castor oil and / or with Cι_8- Alkyl alcohols contains ring-opened epoxidized fatty acid esters.

Accordingly, the subject of the invention is the use of an aqueous polyurethane dispersion with a solids content of between 10 and 50% by weight and a Brookfield viscosity at 20 ° C. of between 10 and 5000 mPas, the polyurethane solids, based on 100 parts by weight of di- and / or Contains polyisocyanates, 61 to 450 parts by weight of castor oil and / or epoxidized fatty acid esters ring-opened with Cι_8-alkyl alcohols, in the leather finishing.

Preferably a polyurethane dispersion is used, the polyurethane solids, based on 100 parts by weight of di- and / or polyisocyanates, 80 to 200 parts by weight of castor oil and / or with Ci-8-alkyl alcohols contains ring-opened epoxidized fatty acid esters.

Epoxidized fatty acid esters, the epoxy rings of which are opened with Ci-8-alkyl alcohols, are preferably epoxidized fatty acid mono-, di- and / or triglycerides which are obtained by epoxidation of unsaturated oils, especially soybean oil, linseed oil, talc oil, construction oil seed oil, peanut oil , Palm oil, sunflower oil, rape oil and / or claw oil are accessible. According to the process described in DE-PS 857-364, unsaturated fatty acid esters can be epoxidized by reaction with peracetic acid in the presence of acidic catalysts or with performic acid formed in situ from formic acid and hydrogen peroxide. Then ^' the epoxidized fatty acid esters with monohydric C 8 alkyl alcohols, for example methanol, ethanol, n-propanol, isopropanol, n-butanol, n-pentanol, n-hexanol, 2-ethylhexanol, n-heptanol and / or n-octanol , but preferably with methanol in the presence of catalysts, for example sodium methylate or potassium hydroxide, at temperatures between 40 and 160 ° C and pressures between 10 ⁴ and 3 * 10 ^ Pa.

As a further polyol component, the polyurethanes to be used according to the invention may contain polyester polyols which are composed of aliphatic and / or aromatic dicarboxylic acids and diols. Suitable aliphatic dicarboxylic acids are, for example, succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, brassylic acid and / or dimer fatty acids. Examples of suitable aromatic dicarboxylic acids are phthalic acid, isophthalic acid, terephthalic acid and / or tetrahydrophthalic acid. Adipic acid is preferred as the aliphatic dicarboxylic acid and isophthalic acid is preferred as the aromatic dicarboxylic acid. The dicarboxylic acids mentioned are mixed in a manner known per se with diols, for example ethylene glycol, 1,2-propanediol, 1,3-propanediol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,10-decanediol, dimerocenol (SovermolR 650NS, Henkel KGaA) and / or neopentylglycol, esterified.

The polyurethanes to be used according to the invention may also contain polyether polyols with average molecular weights between 1,000 and 20,000, preferably between 3,000 and 12,000. Polyether polyols of the general formula are particularly preferred

in which R denotes an alkoxy radical which is derived from glycerol, diglycerol, polyglycerol with a degree of polymerization x between 3 and 6, trimethylolpropane or trimethylolethane, the index x means the degree of polymerization of the alkoxy radical, the indices y are a number between 1 and 8 and z means a number between 0 and 8, with the proviso that the sum y + z is between 1 and 8, the indices a a number between 1 and 15, b a number between 20 and 100, c a number between 1 and 15, d is a number between 20 and 150 and e is a number between 1 and 15, with the proviso that - based on all ethylene oxide and propylene oxide units of the polyether polyol - the sums a + c + e between 3 and 40, b + d are between 40 and 300 and c + e between 1 and 15. Preference is given to those polyether polyols of the general formula in which R is an alkoxy radical derived from glycerol or trimethylolpropane, the indices y 2 or 3 and z are 0 or 1, with the proviso that the sum y + z 2 or 3, and the indices a _f c and e each represent a number between 1 and 5 and b and d each represent a number between 30 and 100, with the proviso that based on all ethylene oxide and propylene oxide units of the polyether polyol - the sums a + c + e between 3 and 20, b + d between 60 and 200 and c + e between 1 and 10. The polyether polyols of the general formula are known compounds which are prepared in a manner known per se by alkoxylation of glycerol, diglycerol, polyglycerol with a degree of polymerization between 3 and 6, trimethylolpropane or trimethylolethane with ethylene oxide and propylene oxide at temperatures between 110 and 200 ° C. and pressures between 10 ^ and 2-10 ^ Pa are accessible.

In order to ensure dispersibility in water, dihydroxy and / or diamino compounds which contain at least one anionic group, preferably one or more carboxylate, sulfonate and / or ammonium groups, for example dimethylolpropionic acid, are used in the production of polyurethanes to be used according to the invention. Tartaric acid and / or 2,4-diaminobenzenesulfonic acid.

The polyurethanes to be used according to the invention contain, based on 100 parts by weight of isocyanate component, 61 to 450 parts by weight of castor oil and / or epoxidized fatty acid esters ring-opened with C8 -8 alkyl alcohols, 0 to 300 parts by weight of polyester polyols, 0 to 60 parts by weight of polyether polyols and 5 to 50 parts by weight bearing at least one anionic group Dihydroxy and / or diamino compounds, preferably 80 to 200 parts by weight of castor oil and / or epoxidized fatty acid esters opened with C 8 alkyl alcohols, 1 to 180 parts by weight of polyester polyols, 0 to 20 parts by weight of polyether polyols and 5 to 30 parts by weight of dihydroxy and at least one anionic group / or diamino compounds, with the proviso that the proportion of the OH equivalents of the polyester polyols, polyether polyols and at least one anionic group Dihydroxy compounds is between 10 and 80%, preferably between 20 and 70% of all OH equivalents.

Suitable organic di- and / or polyisocyanates are aliphatic and / or aromatic di- and / or triisocyanates, for example dicyclohexylmethane-4,4'-diisocyanate, 1,6-hexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate ( Isophorone diisocyanate), tetramethylene diisocyanates, trimethylhexamethylene diisocyanate, dimer fatty acid diisocyanates, 1,4-phenylene diisocyanate, diphenyl ethane diisocyanate, toluene-2,4- and / or toluene-2,6-diisocyanate, 2.4 _f 4'- Trιisocyanato-diphenyl ether and / or 4 ', 4'',4' -Triisocyanato-triphenyl ethane. Aliphatic diisocyanates, in particular isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,6-hexane diisocyanate and / or dimer fatty acid diisocyanates, are preferred.

Furthermore, so-called blocked di- and / or polyisocyanates can be used alone or in combination with the above-mentioned unblocked di- and / or polyisocyanates. The blocked di- and polyisocyanates are resistant to hydroxyl groups at room temperature and only react at temperatures above 50 ° C. Based on the total amount of the di- and / or polyisocyanates used, the content of blocked di- and / or polyisocyanates is preferably between 0 and 60% by weight, particularly preferably between 0 and 10% by weight. Blocked di- and polyisocyanates are produced by reacting organic di- or polyisocyanates, for example isophorone diisocyanate, with an alcohol, for example phenol or m-cresol, in amounts such that all isocyanate groups are blocked.

The polyurethanes to be used according to the invention can be produced by known processes (Ullmann's Encyclopedia of technical chemistry, volume 19, pages 302 ff., Verlag Chemie Wein¬heim, 1980). Di- and / or polyisocyanates with polyols and at least one anionic group containing dihydroxy and / or diamino compounds in the presence of solvents, for example N-methylpyrrolidone and / or methyl ethyl ketone, and, if appropriate, catalysts, such as N-methylmorpholine, are preferably added Temperatures between 60 and 120 ° C converted to prepolymers. The polyurethane prepolymer composition is then dispersed in water and then, if appropriate, reacted with chain extenders, such as alkoxylated glycerols and / or diamines, for example ethylenediamine, hexamethylenediamine and / or piperazine. During the dispersion and chain extension of polyurethanes, the NCO groups still present in the polyurethane prepolymer react with water to form carbon dioxide, which leads to not inconsiderable, disruptive foam formation. When producing a polyurethane dispersion to be used according to the invention, however, such small amounts of foam are formed, if at all, that it is almost always possible to dispense with the addition of defoamers.

A polyurethane dispersion with a high content of castor oil and / or epoxidized fatty acid esters ring-opened with C8-alkyl alcohols as polyol component in the polyurethane solid, a solids content between 10 and 50 wt .-% and a Brookfield viscosity at 20 ° C between 10 and 5000 mPas can be used according to the invention in leather finishing in primer, color and / or finishing liquors. The additive liquors may contain pigment preparations, film-forming substances in the form of aqueous dispersions, such as polyacrylates and / or polyurethanes, binders and fillers, matting agents, penetrators and / or plasticizers as further constituents. The finishing liquors can be applied using all of the technologies customary in leather finishing, for example by spraying, plushing, pouring and / or roller application. The finishing liquors contain polyurethane dispersions to be used according to the invention in amounts of 1 to 60% by weight.

Leather which has been finished with a polyurethane dispersion to be used according to the invention has significantly improved fastness properties, in particular a clearly improved wet rub fastness, compared to leathers which have been finished with a polyurethane dispersion prepared in accordance with DE 37 02 615.

Examples

Production of inventive aqueous polyurethane dispersions

To determine the solids content of the aqueous polyurethane dispersions, 10.0 g of the respective polyurethane dispersion were weighed into an aluminum dish. After drying in the drying cabinet at 125 ° C. for 15 hours, the dry residue was determined by weighing the aluminum pan.

calculation

Dry residue (g) • 100

= Solids content (% by weight)

Weight (g)

example 1

In a well-dried glass laboratory reactor with a 3-stage stainless steel MIG stirrer, 182.6 g of polyester from adipic acid, isophthalic acid and diethylene glycol with an OH number (OHZ) of 59, 129.2 g of soybean oil epoxide were ring-opened at 25 ° C with methanol (OHZ = 200), 30.0 g of diethylolpropionic acid, 27.2 g of N-methylmorpholine and 45.1 g of N-methylpyrrolidone. After homogenization, 146.7 g of isophorone diisocyanate was added to the polyfolder. After the reaction mixture had reached an NCO content of 2.4% by weight after 2.5 hours at 80 ° C., 528.7 g of completely demineralized water at a temperature of 15 ° C. were added to the prepolymer.

Then 3.3 g of glycerol-7 mol of ethylene oxide ^• 81 mol of propylene oxide (OHZ = 34) were added to the 35 ° C. warm polyurethane dispersion for chain extension. After heating to 60 ° C., the polyurethane dispersion foaming due to the carbon dioxide formed from the reaction between the NCO groups and water (Foam height: 3 cm) was stirred at this temperature for 4 hours and then cooled to room temperature. A white, stable, 39.6% by weight aqueous polyurethane dispersion with a pH of 7.1 and a bookfield viscosity at 20 ° C. of 550 mPas was obtained.

Example 2

The polyurethane prepolymer was prepared in the same apparatus as in Example 1. Instead of 129.2 g, 226.1 g of soybean oil epoxide, ring-opened with methanol (OHZ = 200), were used. 528.7 g of completely deionized water at a temperature of 15.degree. C. were then added to the prepoly obtained. After heating to 60 ° C., the mixture was stirred at this temperature for 4 hours (foam height: 1 cm) and then cooled to room temperature. A white, stable, 40.4% by weight aqueous polyurethane dispersion with a pH of 7.2 and a Brookfield viscosity at 20 ° C. of 3500 mPas was obtained.

Comparative Example 1 (according to DE 3702615)

A polyurethane dispersion was prepared in the same apparatus as in Example 1. Instead of 129.2 g, however, 64.6 g of soybean oil epoxide, ring-opened with methanol (OHZ = 200), were used. After adding 3.3 g of glycerol ^• 7 mol of ethylene oxide ^• 31 mol of propylene oxide (OHZ = 34) and heating to 60 ° C., foam formation occurred (foam height: 9 cm). After stirring for 4 hours at 60 ° C., the mixture was cooled to room temperature. A white, stable, 40.2% by weight aqueous polyurethane dispersion with a pH of 7.0 and a Brookfield viscosity at 20 ° C. of 800 mPas was obtained. Example 3

The polyurethane dispersion was prepared analogously to Example 1 in the same apparatus at the same level. Instead of 129.2 g soybean oil epoxide, ring-opened with methanol, 129.2 g castor oil (OHZ = 158) were used. After adding 3.3 g of glycerol ^• 7 mol of ethylene oxide ^• 81 mol of propylene oxide (OHZ = 34) and heating to 60 ° C, small amounts of foam were formed (foam height: 3 cm). A white, stable, 39.3% by weight aqueous polyurethane dispersion with a pH of 7.1 and a Brookfield viscosity at 20 ° C. of 2500 mPas was obtained.

Example 4

The polyurethane dispersion was prepared in the same apparatus as in Example 2. Instead of 226.1 g of soybean oil epoxide, ring-opened with methanol, 226.1 g of castor oil (OHZ = 158) were used. After the dispersion had been heated to 60 ° C., small amounts of foam were formed (foam height: 2 cm). A white, stable, 40.9% by weight aqueous polyurethane dispersion with a pH of 7.4 and a Brookfield viscosity at 20 ° C. of 4200 mPas was obtained.

Comparative Example 2 (according to DE 3702 615)

The polyurethane dispersion was prepared in the same apparatus as in Example 3. Instead of 129.2 g, 32.3 castor oil (OHZ = 158) was used. After adding 3.3 g of glycerol ^• 7 moles of ethylene oxide • 81 moles of propylene oxide (OHZ = 34) and heating to 60 ° C, the polyurethane dispersion expanded (foam height: 14.5 cm). A white, stable, 39.9% by weight aqueous polyurethane dispersion with a pH of 7.0 and a Brookfield viscosity at 20 ° C. of 1800 mPas was obtained. Examples of use

Tl means parts by weight

Base material: natural crust leather

Head coloring: 100 parts of metal complex dye solution 200 parts of polyglycol ether 200 parts of water

Spray cross once

Primer: 100 parts of pigment

30 parts of wax dispersion

10 parts oil emulsion

200 parts of polyacrylate dispersion

300 parts of water

Spray 2 times cross iron 80 ° C / 100 bar Spray 1 time cross

Conclusion: 100 parts of polyurethane dispersion according to the invention (see table) 100 parts of water

Spray cross twice

The wet rub fastness of the finished leather was determined according to Veslic. Rating scale of the wet rub fastness: grade 5 = no abrasion, grade 4 = low abrasion, grade 3 = significant abrasion, grade 2 = strong abrasion, grade 1 = very strong abrasion.

Table 1

Polyurethane dispersion wet rub fastness produced according to the example number of strokes

500

Comparison 1,200

300

Comparison 2,200 3-4

Claims

1. Use of an aqueous polyurethane dispersion with a solids content between 10 and 50 wt .-% and a Brookfield viscosity at 20 ° C between 10 and 5000 mPas, their polyurethane solids, based on 100 parts by weight of di- and / or polyisocyanates, 61 to Contains 450 parts by weight of castor oil and / or epoxidized fatty acid esters ring-opened with C8 alkyl alcohols in the leather finishing.

2. Use according to claim 1, characterized in that a polyurethane dispersion whose polyurethane solids, based on 100 parts by weight of di- and / or polyisocyanates, contains 80 to 200 parts by weight of castor oil and / or epoxidized fatty acid esters ring-opened with C 8 alkyl alcohols becomes.

3. Use according to one or both of claims 1 to 2, characterized in that the polyurethane dispersion to be used contains castor oil and / or epoxidized fatty acid mono-, di- and / or triglycerides opened with C8_8 alkyl alcohols.

4. Use according to claim 3, characterized in that with Ci-8-alkyl alcohols ring-opened epoxidized fatty acid mono-, di- and / or triglycerides with methanol ring-opened soybean oil, linseed oil, tall oil, cottonseed oil, peanut oil, Palm oil, sunflower oil, rape oil and / or claw oil epoxy are.