JP2003171417A - Water-resistant polyvinyl alcohol-based copolymer and synthetic resin emulsion obtained with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vinyl alcohol-based polymer having a high water-resistant performance and excellent aqueous solution viscosity stability. <P>SOLUTION: This vinyl alcohol-based polymer having saturated cyclic alkyl groups on side chains and exhibiting a high water-resistant performance and excellent aqueous solution viscous stability is obtained by copolymerizing a vinyl ether having a saturated cyclic alkyl group with vinyl acetate and then saponifying the obtained copolymer. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel vinyl alcohol-based copolymer having a saturated cyclic alkyl group and having improved water resistance.

[0002]

2. Description of the Related Art Polyvinyl alcohol (hereinafter abbreviated as "PVA") is known as a vinyl alcohol polymer having a vinyl alcohol unit in its molecule.
It is used for various purposes. However, since PVA is water-soluble, various methods for improving water resistance have been investigated. For example, a method using completely saponified PVA is known. However, in this case, there is a problem that the viscosity stability of the PVA aqueous solution is poor. When partially saponified PVA is used, the viscosity stability of the PVA aqueous solution is good, but there are problems such as insufficient water resistance.

As a method of making PVA water resistant, a method of cross-linking with glyoxal, glutaraldehyde or dialdehyde starch, a water-soluble epoxy compound, a methylol compound, etc. is known. However, in order to make PVA sufficiently water resistant by this method, it is necessary to perform heat treatment at a high temperature for a long time, and there are problems such as poor viscosity stability of the aqueous solution of PVA.

[0004]

An object of the present invention is to provide a novel vinyl alcohol polymer having a saturated cyclic alkyl group in its side chain, which exhibits high water resistance performance found in completely saponified PVA, In addition, the viscosity stability of the aqueous solution must be excellent.

[0005]

Means for Solving the Problems As a result of intensive studies made by the present inventors to solve the above problems, a novel vinyl alcohol polymer having a cyclic alkyl group in its side chain solves the above problems. It was found to be a polymer. This vinyl alcohol-based polymer can be obtained by copolymerizing vinyl ether having a cyclic alkyl group and vinyl acetate and then saponifying.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below. The vinyl alcohol polymer of the present invention has a vinyl alcohol unit in the molecule and a cyclic alkyl group in the side chain.

The vinyl alcohol polymer of the present invention is used for dispersants, adhesives, coatings, emulsifiers, thickeners, flocculants, molded products, soil conditioners, and photosensitizers. When used in the field, its viscosity average degree of polymerization (hereinafter abbreviated as “degree of polymerization”) is 100 to 10,000.
It is possible to preferably use the above, more preferably 2
It is in the range of 00 to 6000, and more preferably 300 to 3000. When the degree of polymerization is less than 100, the characteristics as a vinyl alcohol polymer are not exhibited and the degree of polymerization is 1
If it exceeds 0000, the viscosity will be too high and industrial production will be difficult.

The saponification degree of the water resistant vinyl alcohol polymer is 90.0 mol% or more, preferably 92.0 mol% or more. When the degree of saponification is less than 90 mol%, the crystallinity of the water-resistant vinyl alcohol-based polymer is lowered, and high water resistance cannot be obtained.

The cyclic alkyl group content may be 0.1 to 8 mol% based on the total amount of vinyl alcohol units and vinyl acetate units. More preferably 0.
It is 2 to 4 mol%, more preferably 0.3 to 3 mol%. If it is less than 0.1 mol%, the copolymerization effect of vinyl alcohol is poor, and if it exceeds 8 mol%, the good solubility of PVA in water is lost.

The vinyl alcohol polymer of the present invention can be obtained by copolymerizing a saturated cyclic vinyl ether and vinyl acetate and saponifying it. The saturated cyclic vinyl ethers used are cyclohexyl vinyl ether, 2 methyl cyclohexyl vinyl ether, 3 methyl cyclohexyl vinyl ether, 2 hydroxy cyclohexyl vinyl ether, 3 hydroxy cyclohexyl vinyl ether.

To copolymerize vinyl acetate and saturated cyclic vinyl ether, these unsaturated monomers are polymerized by a known method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method or an emulsion polymerization method. 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 lower alcohol such as methyl alcohol or ethyl alcohol is industrially suitable.
In this case, a solvent such as acetone, methyl acetate or toluene may be contained within a range that does not affect the polymerization. As the initiator used for the copolymerization, 2,2′-azobisisobutyronitrile (hereinafter abbreviated as “AIBN”), 2,2′-azobis (2,4-dimethylvaleronitrile), benzoyl peroxide Examples thereof include known radical polymerization initiators such as azo initiators such as n-propyl peroxycarbonate and peroxide initiators. The polymerization temperature is not particularly limited, but is preferably in the range of 40 ° C to the boiling point of the solvent or monomer.

In the polymerization, an unsaturated monomer, a solvent and an initiator are charged into a reaction vessel, and dissolved oxygen in the system is purged by bubbling nitrogen gas, and the temperature inside the reaction vessel is raised to a predetermined temperature.
Copolymerization can be carried out by a known reaction method in which the reaction is performed up to a target polymerization rate and the polymerization is stopped by cooling. A method in which a part of the saturated vinyl ether is initially charged and the rest is dividedly added or continuously added is also possible.

The vinyl alcohol polymer of the present invention contains another monomer in an amount of 30 mol% with respect to the total of vinyl alcohol units and vinyl acetate units within the range not impairing the object of the present invention.
It is also possible to copolymerize within the following range. The monomers are exemplified below. (1) Carboxylic acid vinyl esters: vinyl formate other than vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caprate, vinyl laurate, vinyl versatate, vinyl pivalate, vinyl palmitate, vinyl stearate, etc. (2) Alkyl allyl ethers: propyl allyl ether, butyl allyl ether, hexyl allyl ether, octyl allyl ether, decyl allyl ether,
Dodecyl allyl ether, tetradecyl allyl ether, hexadecyl allyl ether, octadecyl allyl ether, etc. (3) Allyl esters of saturated carboxylic acid: allyl stearate, allyl laurate, allyl coconut oil fatty acid, allyl octylate, allyl butyrate and the like. (4) α-olefins: ethylene, propylene, α-
Hexene, α-octene, α-decene, α-dodecene,
α-hexene, α-octadecene, etc. (5) Others: (meth) acrylamide, (meth) acrylonitrile, (meth) allyl sulfonate, (meth)
Acrylic acid or its alkyl ester.

After the completion of the polymerization, unreacted monomers are removed with alcohol vapor and the alcohol solution of the copolymer is saponified to obtain the desired vinyl alcohol polymer. The concentration of the copolymer in alcohol is usually 2
It is 0 to 50% by weight.

The copolymer obtained as described above is saponified by a known method using an alkali catalyst such as sodium hydroxide or sodium alcoholate in a state of being dissolved in alcohol, or hydrous alcohol in some cases, to give a vinyl alcohol polymer. It can be manufactured. The amount of these catalysts used is preferably in the range of 1/10 to 1/300 molar equivalent with respect to the copolymer. The temperature of the saponification reaction is not particularly limited, but is usually preferably in the range of 20 to 60 ° C.

After the saponification, the vinyl alcohol polymer is subjected to dealcoholization treatment and dried to remove the solvent.
The desired vinyl alcohol polymer can be obtained.

Since the vinyl alcohol polymer thus obtained is used for various purposes, its examples will be specifically described below. (1) Dispersant applications: Dispersion stabilizers for organic and inorganic pigments such as paints, India ink, watercolor colors, and adhesives, suspension of various vinyl compounds such as vinyl chloride, vinylidene chloride, styrene, (meth) acrylate, vinyl acetate. Dispersion stabilizers and dispersion aids for polymerization. (2) Adhesive applications: adhesives for wood, paper, aluminum foil, plastics, adhesives, rewetting adhesives, binders for non-woven fabrics, fiber binders, binders for various building materials such as gypsum board and fiber board, various powders Binder for granulation, ceramics binder, additive for cement and mortar, hot melt adhesive, pressure sensitive adhesive, fixing agent for dye. (3) Coating agent use: clear coating agent for paper, pigment coating agent for paper, internal sizing agent for paper, thermal recording paper binder, sizing agent for textile products, warp sizing agent, textile finishing agent, leather finishing agent, Paints, anti-fog agents, metal corrosion inhibitors, zinc plating brighteners, antistatic agents. (4) Application of emulsifier: emulsifier for emulsion polymerization of ethylenically unsaturated compound, butadiene unsaturated compound, hydrophobic resin such as polyolefin and polyester resin, epoxy resin,
Post-emulsifier for paraffin, picumen, etc. Examples of the ethylenically unsaturated compound include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate,
(Meth) acrylic acid esters such as 2-ethylhexyl (meth) acrylate; aromatic vinyl compounds such as styrene and vinyltoluene; vinyl acetate, vinyl propionate,
Vinyl esters such as vinyl versatate; (meth)
Unsaturated acids such as acrylic acid, itaconic acid, crotonic acid, maleic acid, vinyl sulfonic acid; ethylene, propylene,
Olefins such as isobutylene; (meth) acrylic acid 2
-Hydroxyethyl, (meth) acrylamide and its N-methylol compound, acrylonitrile, vinyl chloride, vinylidene chloride, etc. are mentioned, and these are used individually or in mixture of 2 or more types. (5) Flocculant use: Flocculant for suspended solids and dissolved substances,
A drainage improver for pulp slurry. (6) Molded product use: fiber, film, sheet, pipe,
Tubes, leakproof membranes, water soluble fibers for chemical lace, sponges (7) Photosensitizer applications:

[0018]

EXAMPLES The present invention will now be described in detail with reference to examples and comparative examples. In the following Examples and Comparative Examples, "part" means "part by weight" and "%" means "% by weight". The analysis, water resistance, and water resistance of the emulsion of the obtained polyvinyl alcohol-based copolymer of the present application were evaluated as follows.

The saturated cyclic alkyl group unit in the vinyl alcohol polymer was quantified by 400 MHz ¹ H-NMR. D ₂ O was used as the solvent for the vinyl alcohol-based polymer at the time of ¹ H-NMR measurement. The saponification degree of vinyl acetate unit was measured according to JIS K 6726.

(1) Measurement of viscosity average degree of polymerization When the saponification degree is less than 99.5 mol%, the saponification degree is 9
The intrinsic viscosity [η] (g / dl) of PVA saponified up to 9.5 mol% or more, measured at 30 ° C. with an Ostwald viscometer using ion-exchanged water as a solvent.
From this, the viscosity average degree of polymerization (P) was determined by the following formula.

[0021]

[Formula 1]

(2) Evaluation of water resistance of film After a predetermined PVA was dispersed in distilled water so that the dissolved concentration was 10%, the mixture was heated and stirred at a temperature of 95 ° C. for 1 hour to prepare an aqueous PVA solution, Then, it was cooled to 20 ° C. and cast film-formed to form a film having a thickness of 100 μm (a). A part of the obtained film was heat-treated at 105 ° C. for 2 hours (b). The test body membranes (a, b) were immersed in water at 20 ° C. for 1 hour, then taken out, dried, and weighed to calculate the dissolution rate. That is, when the dissolution rate is 100%, the film is completely dissolved, and when the dissolution rate is 0%, the film is not dissolved and the film has excellent water resistance.

(3) Evaluation of Emulsion 455 parts by weight of deionized water was added to a glass polymerization container equipped with a reflux condenser, a dropping funnel, a thermometer, and a nitrogen inlet.
35 parts by weight of a water-resistant vinyl alcohol-based copolymer was added, and heated and stirred to dissolve. After that, the temperature in the polymerization vessel is increased to 7
The temperature was brought to 0 ° C., and 0.05 part by weight of potassium persulfate was added. Next, 420 parts by weight of vinyl acetate was continuously added over 3 hours. After the continuous addition, potassium persulfate 0.05
Polymerization was completed by adding an additional part by weight and performing an aging reaction for 1 hour. The obtained emulsion was evaluated for film water resistance by a water-soluble component test according to JIS K 6828. That is, the dissolution rate is 100%, the film is completely dissolved, and the dissolution rate is 0%.
Therefore, the film does not dissolve and the film has excellent water resistance. In addition, the low temperature stability of the emulsion depends on the initial viscosity (η3
0 ° C) and viscosity at 5 ° C after standing for 1 day at 5 ° C (η5 ° C)
And the ratio (low temperature thickening ratio = η5 ° C / η30 ° C)
The above results were rated as good (◯) and 3 or less were rated as bad (x). The measurement was performed using a B-type viscometer (rotation speed 10 rpm).

(Example 1) A reflux condenser, a monomer addition port,
A 1-liter polymerization vessel equipped with a thermometer, a sampling port, a nitrogen inlet, and a stirrer was charged with 2250 parts of vinyl acetate, 40 parts of cyclohexyl vinyl ether, and 563 parts of methanol, and nitrogen was blown while stirring to perform deoxidation. . Then, when the temperature in the can was stabilized by heating at 62 ° C., 25 parts of a methanol solution in which 1.5 parts of AIBN was dissolved in 25 parts of methanol was added to initiate polymerization. Polymerization was performed while analyzing the solid content concentration in the system, and after 6 hours, the polymerization vessel was cooled to terminate the polymerization. The polymerization rate at that time was 70%. Thereafter, unreacted monomers were removed with methanol vapor to obtain a methanol solution of vinyl acetate / cyclohexyl vinyl ether copolymer. Next, the concentration of this methanol solution was adjusted to 50%, and 387 ml of a methanol solution having a sodium hydroxide concentration of 10% was added while stirring with a kneader whose temperature was adjusted to 35 ° C., and saponification was carried out for 3 hours. . The obtained vinyl alcohol-based polymer was washed with methanol to remove the solvent, and then dried at 90 ° C. for 2 hours to obtain a white powder of vinyl alcohol-based polymer. The content of cyclohexyl vinyl ether units in the obtained vinyl alcohol-based polymer was 6.4 mol% / (polyvinyl alcohol +
Vinyl acetate) and the degree of saponification was 99.5 mol%. The viscosity average degree of polymerization measured using ion-exchanged water as a solvent was 1,700. The physical properties of the vinyl alcohol polymer are shown in Table 1.

(Examples 2 to 5) Copolymerized PVA was obtained in the same manner as in Example 1 except that the amounts of cyclohexyl vinyl ether and methanol were changed. The results are shown in Table 1.

Comparative Examples 1 to 3 Vinyl ester polymers were synthesized in the same manner as in Example 1 except that the comonomers shown in Table 1 were used. The physical properties of the vinyl alcohol polymer are shown in Table 1. In Comparative Example 3, the viscosity was extremely high in the emulsion polymerization evaluation, and the emulsion evaluation could not be performed. The results are shown in Table 1.

Comparative Example 4 Evaluation was made in the same manner as in Example 1 except that ordinary PVA (partially saponified PVA B-17 manufactured by Denki Kagaku Kogyo Co., Ltd.) was used. The water resistance of the obtained film was poorly dissolved completely. Also, good water resistance was not obtained in the emulsion. The results are shown in Table 1.

Comparative Example 5 Evaluation was made in the same manner as in Example 1 except that ordinary PVA (partially saponified PVA K-17E manufactured by Denki Kagaku Kogyo Co., Ltd.) was used. The water resistance of the obtained film and the film water resistance of the emulsion were good, but the low temperature stability of the emulsion was poor. The results are shown in Table 1.

[0029]

[Table 1]

[0030]

The water-resistant polyvinyl alcohol polymer having a cycloalkyl group of the present invention is excellent in emulsifying dispersant, adhesive, surface coating property and the like. Further, the vinyl alcohol-based polymer of the present invention from such properties is not limited to dispersants, adhesives, surface coating agents, coating agents, blending agents for resins, suspension polymerization stabilizers, emulsifiers, flocculants, photosensitizers,
It can be used for various purposes such as molded products, fiber sizing agents, various films and sheets.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08F 216/06 C08F 216/06 F term (reference) 4D015 BA08 BA10 BB05 CA05 DB18 DC03 4D077 AA03 AA07 AB04 AB09 AB14 AC01 AC05 BA01 BA03 DD09X DD15X DE08X 4J011 AA05 BB01 BB02 BB07 BB09 BB12 DA01 DA02 DA04 HA04 HB02 HB22 KA16 KB02 KB09 KB22 KB29 4J100 AA01R AA15 DA AE09Q AE09R AZQR AE14R15AQRQAQR FA03 FA19 FA28 GB09 HA09 HB39 HC09 HC12 JA01 JA03 JA15 JA18 JA58

Claims (5)

[Claims] 1. A polyvinyl alcohol-based copolymer obtained by saponifying a copolymer containing vinyl ether having a saturated cyclic alkyl group and vinyl acetate, wherein the degree of saponification of vinyl acetate units is 90.0 mol% or more. A water-resistant polyvinyl alcohol-based copolymer characterized by being: 2. The water-resistant polyvinyl alcohol-based copolymer according to claim 1, wherein the content of the vinyl ether having a saturated cyclic alkyl group is 0.2 to 4.0 mol%. 3. The water resistant polyvinyl alcohol polymer according to claim 1, wherein the vinyl ether having a saturated cyclic alkyl group is cyclohexyl vinyl ether. 4. The water-resistant polyvinyl alcohol-based polymer according to claim 1, which has a viscosity average degree of polymerization in the range of 300 to 3000. 5. A synthetic resin emulsion obtained by emulsion-polymerizing an ethylenically unsaturated monomer using the water-resistant polyvinyl alcohol polymer according to any one of claims 1 to 4.