JPH08319318A - Vinyl alcohol polymer - Google Patents

Abstract

(57) [Summary] [Structure] A vinyl alcohol polymer having a hydroxyalkyl group having 2 to 20 carbon atoms in its side chain. [Effect] The vinyl alcohol polymer of the present invention is 5%.
The weight loss temperature is higher than 300 ° C, and the thermal stability is excellent. In the case of the conventional water-soluble vinyl alcohol-based polymer, when the surface activity is high, there is a lot of foaming of the aqueous solution, so that there is a problem in industrial use, but the vinyl alcohol-based polymer of the present invention is When it is water-soluble, it has high surface activity, but it is highly industrially useful because the aqueous solution hardly foams. The vinyl alcohol polymer of the present invention is useful as a thermoplastic resin or a dispersion stabilizer. Further, the vinyl alcohol-based polymer of the present invention,
Surfactants for various uses, paper coating agents, paper modifiers such as paper internal additives and pigment binders, wood, paper,
It can be used for various applications such as adhesives for aluminum foil and inorganic materials, non-woven fabric binders, paints, warp sizing agents, fiber processing agents, sizing agents for hydrophobic fibers such as polyesters, various films, sheets, bottles and fibers.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a vinyl alcohol polymer having good thermal stability.

[0002]

2. Description of the Related Art Polyvinyl alcohol (hereinafter abbreviated as "PVA") is known as a typical vinyl alcohol polymer having a vinyl alcohol unit in its molecule. Since PVA is excellent in film-forming property, transparency and strength, it is a paper modifier such as a coating agent for paper and an internal additive for paper; an adhesive agent for paper, wood and inorganic substances;
Widely used in warp sizing agents, films and sheets. As conventional PVA, "completely saponified PVA" having a saponification degree of about 98 mol% and "partially saponified PVA" having a saponification degree of about 88 mol% are known.

Conventional PVA has been used in the form of an aqueous solution because of its poor thermal stability. That is, in the case of "completely saponified PVA", the melting point and the thermal decomposition temperature were very close to each other, and hot melt molding was impossible. On the other hand, in the case of "partially saponified PVA" having a lower melting point than that of "completely saponified PVA", there is a problem that acetic acid odor is generated during hot melt molding because of poor thermal stability. Next, a method has been proposed in which the melt viscosity of PVA is lowered by blending a plasticizer or another polymer with PVA, and the PVA is hot melt-molded. However, the method of adding a plasticizer is such that if the molded product is used for a long period of time, the plasticizer content in the molded product will decrease over time, and the molded product will be flexible under low temperature and low humidity such as in winter. There was a problem that the molded product was cracked or cracked due to lack of properties. On the other hand, the method of blending PVA with another polymer has a problem that the mechanical properties of the molded product are remarkably lowered or the transparency is remarkably lowered due to poor compatibility between the two.

Next, by modifying PVA, PV
A method of lowering the melting point of A has been proposed. However, PVA having an ω-hydroxyalkyl vinyl ether unit and an alkyl vinyl ether unit (JP-B-4-10885) and PVA having a polyoxyethylene monoallyl ether unit (JP-B-5-49683) have an ether bond. In addition, there was a problem of low thermal stability. Further, PVA having an allyl alcohol unit (Japanese Patent Laid-Open No. 62-229135) has a slightly improved thermal stability, but is still insufficient in practical use, and the amount of allyl alcohol remaining in PVA is not sufficient. There was a safety issue. Further, PVA having an α-olefin unit (Japanese Patent Laid-Open No. 63-289581) has problems that the melt viscosity is remarkably increased due to the association of hydrophobic groups and that it is insoluble in water.

[0005]

An object of the present invention is to provide a novel vinyl alcohol polymer having excellent thermal stability. Further, an object of the present invention is to provide a novel vinyl alcohol-based polymer in which, when the vinyl alcohol-based polymer is water-soluble, the aqueous solution has less foaming despite having high surface activity. It is in.

[0006]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found a vinyl alcohol polymer having a hydroxyalkyl group having 2 to 20 carbon atoms in the side chain, The invention was completed.

The vinyl alcohol polymer of the present invention must have a vinyl alcohol unit in the molecule. The side chain of the vinyl alcohol polymer of the present invention is a hydroxyalkyl group having 2 to 20 carbon atoms, and the side chain needs to be directly bonded to the main chain of the vinyl alcohol polymer. The number of carbon atoms of the hydroxyalkyl group of the vinyl alcohol polymer of the present invention is 2 to 20,
15 is preferable and 3-10 is more preferable. The hydroxyalkyl group is an alkyl group having at least one hydroxyl group (hydroxyl group), and a ω-hydroxyalkyl group is more preferable in terms of thermal stability and water solubility. As the alkyl group of the hydroxyalkyl group, its hydrogen atom may be substituted with a linear or branched alkyl group having 1 to 9 carbon atoms. Examples of the monomer unit having a hydroxyalkyl group having 2 to 20 carbon atoms in the side chain include a hydroxyl group-containing olefin unit. Among the hydroxyl group-containing olefin units, from the viewpoint of easiness of controlling the degree of polymerization of the vinyl alcohol-based polymer and easiness of controlling the content of the monomer unit having a hydroxyalkyl group,
3-butene-1-ol, 4-penten-1-ol, 5-hexen-1-ol, 7-octen-1-ol, 9-decen-1-ol, 11-dodecen-1-ol, 3- Methyl-3-butene-1
-A monomer unit derived from all or the like is preferable. In addition to these monomer units, it may be a monomer unit containing an ester group capable of forming a hydroxyl group during the saponification reaction of a vinyl ester polymer which is a raw material for a vinyl alcohol polymer. .

The content of the hydroxyalkyl group having 2 to 20 carbon atoms in the vinyl alcohol polymer of the present invention is not particularly limited, but its preferable content is as follows. When the vinyl alcohol polymer of the present invention is used as a hot melt moldable resin, the content of hydroxyalkyl group is preferably 0.1 to 50 mol%,
30 mol% is more preferable. When the vinyl alcohol-based polymer of the present invention is used for a hot melt moldable resin and a water-soluble application, the content of hydroxyalkyl group is 0.3 to
30 mol% is preferable, and 0.5 to 20 mol% is more preferable. When the vinyl alcohol-based polymer of the present invention is used as a dispersion stabilizer for emulsion polymerization of vinyl ester-based monomers and the like, the content of hydroxyalkyl groups is 0.1 to 0.1%.
25 mol% is preferable, and 0.3 to 15 mol% is more preferable. When the content of the hydroxyalkyl group is less than 0.1 mol%, the degree of improvement in thermal stability, hot melt moldability or surface activity is low. When the content of the hydroxyalkyl group is more than 30 mol%, the water solubility decreases, and
When it is more than mol%, the characteristics as a vinyl alcohol polymer are deteriorated. The degree of saponification of the vinyl alcohol polymer of the present invention is not particularly limited and may be complete saponification or partial saponification, but in view of thermal stability and hot melt moldability, it is preferably 50 mol% or more, and 70 mol% or more. Is more preferable, and 80 mol% or more is particularly preferable. The viscosity average degree of polymerization (hereinafter abbreviated as “degree of polymerization”) of the vinyl alcohol polymer of the present invention is preferably 100 to 20000, more preferably 200 to 8000, and 300 to 5
000 is particularly preferred. When the degree of polymerization is less than 100, the characteristics as a vinyl alcohol polymer are deteriorated,
When the degree of polymerization is more than 20000, industrial production of vinyl alcohol polymer is difficult.

As the method for producing the vinyl alcohol polymer of the present invention, a vinyl ester polymer obtained by copolymerizing a vinyl ester and a hydroxyalkyl group-containing olefin is saponified in an alcohol or dimethylsulfoxide solution. Known methods such as Examples of the vinyl ester include vinyl formate, vinyl acetate, vinyl propionate, vinyl pivalate and the like, with vinyl acetate being preferred.

The vinyl alcohol polymer of the present invention may be a copolymer of a copolymerizable ethylenically unsaturated monomer as long as the effect of the present invention is not impaired. As the ethylenically unsaturated monomer, olefins such as ethylene, propylene, 1-butene and isobutene; acrylic acid, methacrylic acid, crotonic acid, (anhydrous) phthalic acid, (anhydrous)
Unsaturated acids such as maleic acid and (anhydrous) itaconic acid or salts thereof or mono- or dialkyl esters having 1 to 18 carbon atoms; acrylamide, N having 1 to 18 carbon atoms
-Acrylamidos such as alkyl acrylamide, N, N-dimethyl acrylamide, 2-acrylamidopropanesulfonic acid or a salt thereof, acrylamidopropyldimethylamine or an acid salt thereof or a quaternary salt thereof; methacrylamide, N- having 1 to 18 carbon atoms Methacrylamides such as alkylmethacrylamide, N, N-dimethylmethacrylamide, 2-methacrylamidopropanesulfonic acid or its salt, methacrylamidopropyldimethylamine or its acid salt or its quaternary salt; N-vinylpyrrolidone, N- N-vinylamides such as vinylformamide and N-vinylacetamide; vinyl cyanides such as acrylonitrile and methacrylonitrile; alkyl vinyl ethers having 1 to 18 carbon atoms, hydroxyalkyl Vinyl ether, vinyl ethers such as alkoxides comb alkyl vinyl ethers; vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, vinyl halides such as vinyl bromide; vinylsilane such as trimethoxyvinylsilane, allyl acetate,
Allyl chloride, allyl alcohol, dimethylallyl alcohol, trimethyl- (3-acrylamido-3-dimethylpropyl) -ammonium chloride, acrylamido-2-methylpropanesulfonic acid and the like can be mentioned. Further, the vinyl alcohol-based polymer of the present invention, thiol acetic acid, in the presence of a thiol compound such as mercaptopropionic acid, a vinyl ester-based monomer such as vinyl acetate,
It may be a terminal modified product obtained by copolymerizing with a hydroxyalkyl group-containing olefin and saponifying it.

As the method for copolymerizing the vinyl ester and the hydroxyalkyl group-containing olefin, a bulk polymerization method,
Known methods such as a solution polymerization method, a suspension polymerization method and an emulsion polymerization method can be mentioned. Among them, the bulk polymerization method or the solution polymerization method in which the polymerization is carried out without solvent or in a solvent such as alcohol is usually adopted, and when a high degree of polymerization is obtained, emulsion polymerization is adopted. Examples of the alcohol used as the solvent during the solution polymerization include lower alcohols such as methyl alcohol, ethyl alcohol and propyl alcohol. As the initiator used for the copolymerization, α, α′-azobisisobutyronitrile, 2,2′-azobis (2,2
4-dimethyl-valeronitrile), benzoyl peroxide,
Known initiators such as azo-based initiators such as n-propyl peroxycarbonate or peroxide-based initiators may be mentioned. The polymerization temperature is not particularly limited, but may be room temperature to
A range of 150 ° C is suitable.

The copolymer of vinyl ester and olefin containing hydroxyalkyl group is saponified in a state of being dissolved in alcohol, or hydrous alcohol in some cases. Examples of the alcohol used in the saponification reaction include lower alcohols such as methyl alcohol and ethyl alcohol, and methyl alcohol is particularly preferably used. The alcohol used in the saponification reaction may contain a solvent such as acetone, acetic acid methyl ester, acetic acid ethyl ester and benzene as long as it is 40% by weight or less. As a catalyst used in the saponification reaction, an alkali metal hydroxide such as potassium hydroxide or sodium hydroxide, an alkali catalyst such as sodium methylate, or an acid catalyst such as a mineral acid is used. The temperature of the saponification reaction is not particularly limited, but the range of 20 to 60 ° C is suitable. When a gel-like product is deposited as the saponification reaction proceeds, the vinyl alcohol polymer of the present invention can be obtained by crushing the product at that time, washing and then drying.

The vinyl alcohol polymer of the present invention is remarkably excellent in thermal stability as compared with conventional PVA.
That is, the vinyl alcohol polymer of the present invention is a temperature at which the weight of the polymer, which is an index of thermal stability, is reduced by 5% (hereinafter abbreviated as "5% weight loss temperature"; see the section of Examples).
Is higher than 300 ° C. Industrial thermo-melt molding of thermoplastic resins such as polyolefin is often carried out at a temperature of 250 ° C. or lower, but considering long-term operability (long run property), the actual thermo-melt molding temperature is 5% by weight. It is necessary to set the temperature 50 ° C or more lower than the decreasing temperature. Therefore, it can be said that the vinyl alcohol-based polymer of the present invention having a 5% weight loss temperature of higher than 300 ° C. is remarkably excellent in industrial hot melt moldability. The vinyl alcohol polymer of the present invention has a low saponification degree and partially saponified PVA.
In the case of, the thermal stability is also good, and in particular, melt molding at high temperature becomes possible. The reason why the vinyl alcohol polymer of the present invention exhibits high thermal stability is not clear,
It is presumed that this is due to the side chain (hydroxyalkyl group having 2 to 20 carbon atoms) directly connected to the main chain of the vinyl alcohol polymer.

The vinyl alcohol polymer of the present invention includes:
A plasticizer may be used to further improve the hot melt moldability. As the plasticizer, ethylene glycol, diethylene glycol, triethylene glycol,
Glycols such as tetraethylene glycol, polyethylene glycol having a molecular weight of 600 or less, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol and propylene glycol; glycerin, 1,3-butanediol, 2,
Known diols such as 3-butanediol and the like; trimethylolpropane, diglycerin, 3-methyl-1,3,5 pentanetriol, and a small amount (20% or less) of water can be used, but not limited thereto. The addition amount of the plasticizer is preferably 30 parts by weight or less based on 100 parts by weight of the vinyl alcohol polymer, and 2
It is more preferably 0 part by weight or less, still more preferably 10 parts by weight or less.

The vinyl alcohol polymer of the present invention includes
It is also possible to use a mixture of an inorganic material having a low reactivity with a vinyl alcohol polymer such as a clay mineral, an inorganic salt or glass. As inorganic materials, kaolin, clay, talc, acid clay, silica, alumina, diatomaceous earth, bentonite, montmorillonite, kibushi clay, frog clay, wax stone, alum stone, porcelain clay, feldspar, asbestos, perlite, calcium carbonate Known materials such as magnesium hydroxide, carbon black, titanium oxide, mica, shirasu, glass and glass fiber can be used. The average particle size of the inorganic material that can be used in the present invention is not particularly limited, but 0.1
˜100 μm is preferred. The amount of inorganic material added is
200 per 100 parts by weight of vinyl alcohol polymer
The amount is preferably 0 parts by weight or less, more preferably 1000 parts by weight or less.

As the method for molding the vinyl alcohol polymer of the present invention, a method of molding from the form of a solution of water or dimethylsulfoxide, which is a solvent for the vinyl alcohol polymer of the present invention, a vinyl alcohol polymer by heating. Examples of the method include plasticizing and molding (eg, extrusion molding method, injection molding method, inflation molding method, press molding method, blow molding method). By these methods, molded articles of arbitrary shapes such as films, sheets, tubes and bottles can be obtained.

When the vinyl alcohol polymer of the present invention is water-soluble, the aqueous solution is less likely to foam even though it has an extremely high surface activity. The reason for this is
Although not clear, a side chain directly connected to the main chain (having 2 to 2 carbon atoms)
0 hydroxyalkyl group). INDUSTRIAL APPLICABILITY The vinyl alcohol polymer of the present invention has extremely excellent surface activity and little foaming in an aqueous solution, and therefore is useful as a dispersion stabilizer, a coating agent, a sizing agent, a binder and the like.

[0018]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples. In the following examples and comparative examples, "parts" and "%" mean weight basis unless otherwise specified.

The content of side chain hydroxyalkyl groups, vinyl ester units, vinyl alcohol units and other comonomer units in the vinyl alcohol polymer is 270.
It was quantified by MHz ¹ H-NMR. Deuterated DMSO was used as a solvent in the PVA-based polymer at the time of ¹ H-NMR measurement. The degree of polymerization, water solubility, thermal stability, surface tension and viscosity of a 4% aqueous solution of the vinyl alcohol polymer were measured by the following methods.

(1) Viscosity average degree of polymerization When the degree of saponification is less than 99.5 mol%, the degree of saponification is 9
For PVA saponified up to 9.5 mol% or more, the intrinsic viscosity [η] (g / d) measured at 30 ° C. in water.
It is represented by the viscosity average degree of polymerization (P) obtained from the following equation from l). P = ([η] × 10 ³ /8.29) ^{(1 / 0.62)}

(2) Water solubility An aqueous solution having a concentration of 10% was prepared and visually evaluated.
The results are shown by the following symbols. ◯: It dissolves in water. X: Does not dissolve in water.

(3) Thermal Stability The purified PVA dried under reduced pressure at 105 ° C. for 5 hours or longer was heated to 70 ° C. under a nitrogen atmosphere at a temperature rising rate of 10 ° C./min.
TG-DTA (differential thermal analysis) under the condition of raising the temperature to 0 ° C.
Was measured and the 5% weight loss temperature was determined.

(4) Surface tension After preparing a 0.3% aqueous solution of PVA at 20 ° C for 60 minutes, the surface tension was measured by the Wilhelmy method (plate method).

(5) 4% Aqueous Solution Viscosity A 4% aqueous solution of PVA at 20 ° C. was prepared and the B type viscosity (Brookfield viscosity) was measured.

(6) Foamability of Aqueous Solution A 4% aqueous solution of PVA at 20 ° C. was prepared and placed in a vertically standing glass tube (inner diameter 4.5 cm, height 150 cm) at a depth of 20.
The mixture was charged to a volume of 1.5 cm and pumped at a rate of 1.5 liters / minute for 15 minutes (the aqueous solution was drawn from the lower part of the glass tube and returned to the uppermost part of the glass tube). Was measured. The results are shown by the following symbols. ⊚: Height of bubbles generated 49 cm or less ○: Height of bubbles generated 50 to 74 cm Δ: Height of bubbles generated 75 to 99 cm ×: Height of bubbles generated 100 cm or more

Example 1 1680 g of vinyl acetate and 7-octene-1-ol were placed in a 3 liter polymerization tank equipped with a reflux condenser, a stirrer, a thermometer, a nitrogen introducing tube, a charging port for a post-added liquid and a pump. 350 g,
420 g of methanol was charged. While stirring the polymerization liquid, the system was replaced with nitrogen and heated, and when the temperature reached a constant temperature of 60 ° C,
2,2'-Azobisisobutyronitrile (hereinafter "AIBN"
Abbreviated) was added to initiate polymerization. Polymerization was performed while analyzing the solid content concentration in the system from the start of the polymerization.
After a lapse of time, the polymerization was stopped by cooling the polymerization tank.
The polymerization rate before the termination of the polymerization was 59%. The obtained polymerized paste was dropped into n-hexane to precipitate a polymer. Next, after dissolving the polymer in acetone and performing reprecipitation-purification operation in which it is precipitated in n-hexane three times, it is again dissolved in acetone, dropped in distilled water, purified by boiling, and then at 60 ° C. Dry and purified polyvinyl vinyl acetate (hereinafter "PVAc")
Abbreviated). Then, a methanol solution with a concentration of purified PVAc of 30% was prepared, and a methanol solution with a concentration of 10% of sodium hydroxide (molar ratio of 0.10 to PVAc) was added with stirring at 40 ° C. and saponification for 60 minutes. The reaction was carried out. The obtained gel-like material is crushed and then immersed in methanol to obtain a 10% sodium hydroxide methanol solution (P
A molar ratio to VAc of 0.02) was added and re-saponification was performed for 5 hours. The obtained PVA was washed with methanol and dried at 50 ° C. for 18 hours to obtain PVA as a white powder. The content of 7-octen-1-ol unit in the obtained PVA was 4.
It was 5 mol%. Table 2 shows the basic structure and physical properties of PVA.
And shown in Table 3.

Example 2 The following polymerization was carried out in the same manner as in Example 1 using 5 liters of the polymerized layer. 2800 g of vinyl acetate, 300 g of 7-octen-1-ol and 700 g of methanol were charged.
While stirring the polymerization solution, the system was replaced with nitrogen and heated to 60
When the temperature reached a constant temperature of ° C, 33 g of AIBN was added to start the polymerization, and after 4.5 hours, the polymerization was stopped when the conversion reached 63%. Purified PVAc was obtained in the same manner as in Example 1, followed by saponification and purification to obtain purified PVA. The content of 7-octen-1-ol units in the obtained PVA was 8.4 mol%. The basic structure and physical properties of PVA are shown in Tables 2 and 3.

Examples 3 to 8 Polymerization, saponification and purification were carried out in the same manner as in Example 1 except that the polymerization conditions shown in Table 1 were changed.
I got Tables 2 and 3 show the basic structure and physical properties of PVA.
Shown in

Example 9 The following polymerization was carried out in the same manner as in Example 2 using a 5 liter polymerization tank. 2800 g of vinyl acetate, 800 g of 7-octen-1-ol, 30 g of sodium allyl sulfonate
I prepared it. While stirring the polymerization liquid, the system was replaced with nitrogen and heated, and when the temperature reached a constant temperature of 60 ° C, 30 g of AIBN was added to start the polymerization, and the polymerization rate became 38% after 5 hours. At that point the polymerization was stopped. Purified P in the same manner as in Example 1.
Purified PVA was obtained by obtaining VAc, followed by saponification and purification. 7-octene in the PVA obtained
The content of -1-ol unit was 11.0 mol% and the content of sodium allylsulfonate unit was 0.5 mol%. The basic structure and physical properties of PVA are shown in Tables 2 and 3.

Example 10 10.2-mol% of 5-hexen-1-ol obtained in Example 4
The contained PVAc was saponified by adding a 10% sodium hydroxide solution in methanol (molar ratio to PVAc: 0.009). The obtained gel-like substance was crushed, washed with methanol, and dried at 50 ° C for 18 hours to obtain a white powder of PVA.
I got Tables 2 and 3 show the basic structure and physical properties of PVA.
Shown in

Example 11 PVAc containing 4.5 mol% of 7-octen-1-ol obtained in Example 1 was mixed with 10% sodium hydroxide.
The solution was saponified by adding a methanol solution of the above (0.009 molar ratio to PVAc). The obtained gel-like substance was crushed, washed with methanol, and dried at 50 ° C. for 18 hours to obtain P as a white powder.
VA was obtained. The basic structure and physical properties of PVA are shown in Tables 2 and 3.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

[Table 3]

Comparative Examples 1 to 10 In the same manner as in Example 1, the physical properties of PVA shown in Table 4 were evaluated. The results are shown in Table 5.

[0036]

[Table 4]

[0037]

[Table 5]

[0038]

The vinyl alcohol polymer of the present invention is
The 5% weight loss temperature is higher than 300 ° C, and the thermal stability is excellent. In the case of the conventional water-soluble vinyl alcohol-based polymer, when the surface activity is high, there is a lot of foaming of the aqueous solution, so that there is a problem in industrial use, but the vinyl alcohol-based polymer of the present invention is When it is water-soluble, it has high surface activity, but it is highly industrially useful because the aqueous solution hardly foams. The vinyl alcohol polymer of the present invention is useful as a thermoplastic resin or a dispersion stabilizer. Further, the vinyl alcohol-based polymer of the present invention is a surfactant for various uses, a paper coating agent, a paper modifier such as a paper internal additive and a pigment binder, wood,
It can be used for various applications such as adhesives for paper, aluminum foil and inorganic materials, non-woven fabric binders, paints, warp sizing agents, fiber processing agents, sizing agents for hydrophobic fibers such as polyesters, various films, sheets, bottles and fibers.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Toshiaki Sato 1621 Sakata, Kurashiki City, Okayama Prefecture Kuraray Co., Ltd.

Claims (2)

[Claims] 1. A vinyl alcohol polymer having a hydroxyalkyl group having 2 to 20 carbon atoms in a side chain. 2. The vinyl alcohol polymer according to claim 1, wherein the hydroxyalkyl group is an ω-hydroxyalkyl group.