JP2002088214A - Resin composition and paper coating agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition which gives a water solution having a good viscosity stability and hence being excellent in workability and exhibits excellent water resistance even when dried at a relatively low temperature; and a paper coating agent prepared by using the same. SOLUTION: This resin composition is prepared by compounding (A) 100 pts.wt polyvinyl alcohol resin with (B) 1-30 pts.wt. polyepoxy compound and (C) 0.5-20 pts.wt. polyvalent metal salt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition having excellent workability and water resistance, and a paper coating agent containing an aqueous solution thereof as a main component.

[0002]

2. Description of the Related Art Conventionally, polyvinyl alcohol (hereinafter abbreviated as PVA) resin is water-soluble,
It has been widely used as a paper coating agent and the like because it can be used in an aqueous system, has excellent film forming properties and film strength in physical properties, and has good compatibility with cellulose.
However, a film obtained from the aqueous solution has poor water resistance, and various methods have been studied for the purpose of improving the water resistance.

For example, a method of adding a crosslinking agent such as a dialdehyde such as glyoxal or a metal salt to an aqueous solution of PVA to make the PVA water-resistant is known. Requires a treatment at high temperature and a treatment under strong acid conditions using an acid catalyst, and the usable applications are limited. Further, a system in which a crosslinking agent is added to a PVA aqueous solution has a problem in workability such as poor viscosity stability of the solution and gelation in a short time after addition.

[0004]

As a method for solving these problems, a method for making water resistant by reacting a hydrazine compound with PVA having an acetoacetyl group (Japanese Patent Publication No. 1-60).
192) and a method for making water resistant by reacting hydrazines with PVA having a diacetone group (JP-A-8-151).
412) has been proposed, and these water-resistant methods do not require special treatment such as heating or addition of a strong acid, and do not generate harmful substances such as formaldehyde. However, even in this system, if a crosslinking agent is added, the reaction proceeds rapidly, and the problem that the pot life in a solution state is short has not been solved.

[0005] The pot life in these solution states is extended,
In order to improve the workability to a practical level, the present inventors, when reacting a hydrazine-based compound with a saponified diacetone acrylamide-fatty acid vinyl ester copolymer, by coexisting an organic amino-based compound, water resistance is improved. A method for improving the pot life without impairment has been proposed (Japanese Patent Application Laid-Open No. Hei 10-87936). Although these systems have greatly improved workability as compared with the prior art, the state of a solution or a mixed solution has been improved. If left for a long period of time, gelation will occur.If the product is used in a high-concentration solution or if it is left at a relatively high temperature, the pot life is not sufficient. During this time, a water-resistant system that does not cause gelation has been desired.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned drawbacks of the prior art, exhibits excellent water resistance even when dried at a relatively high or ordinary temperature, and has a crosslinking agent coexistent in the aqueous solution. However, the purpose of the present invention is to provide a resin composition having excellent workability without thickening and gelling of a solution, and a paper coating agent containing an aqueous solution thereof as a main component.
(B) 1 to 30 parts by weight of a polyfunctional epoxy compound such as ethylene glycol diglycidyl ether and 0.5 to 20 parts by weight of a (C) polyvalent metal salt such as aluminum sulfate are mixed with 100 parts by weight of the PVA resin. (A) a PVA-based resin obtained by copolymerizing and modifying a diacetone acrylamide or an α-olefin unit. Is preferably a PVA-based resin obtained by copolymerizing the above.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The PVA-based resin used as the component (A) of the present invention includes:
Various PVA-based resins obtained by a known method are used. For example, a fatty acid vinyl ester in a lump, a solution,
It is obtained by saponifying a fatty acid vinyl ester polymer obtained by a known polymerization method such as suspension and emulsification by a known method.

Although the degree of saponification of the PVA resin used in the present invention is not particularly limited, the degree of saponification is preferably at least 60 mol%, more preferably at least 80 mol%. There is no limitation on the degree of polymerization of the PVA-based resin.
The viscosity of a 4% by weight aqueous solution at 0 ° C. is 1.5 mPa · s
The above is preferable, and more preferably 3 to 100 mPa · s
Range.

Further, as the PVA resin, diacetone acrylamide or C4
When a PVA-based resin obtained by copolymerizing and modifying the following α-olefin is used, the effect of water resistance as an object of the present invention is high.

Examples of the α-olefin having 4 or less carbon atoms used in the above-mentioned copolymerization modification include, for example, ethylene, propylene, n-butene, isobutene and the like.

The degree of modification of the diacetone acrylamide copolymer modified PVA resin and the α-olefin copolymer modified PVA resin having 4 or less carbon atoms is not particularly limited. Mol%
And more preferably 1 to 10 mol%. In the case of an α-olefin having 4 or less carbon atoms, the content is preferably 1 to 10 mol%, more preferably 2 to 8 mol%.
Diacetone acrylamide and α- having 4 or less carbon atoms
Each olefin may be copolymerized with a fatty acid vinyl ester, but two or more olefins may be copolymerized.

The PVA resin may be a monomer other than diacetone acrylamide copolymerizable with a fatty acid vinyl ester and an α-olefin having 4 or less carbon atoms, as long as the effects of the present invention are not impaired. Alternatively, a modified PVA obtained by modifying a polymer terminal with a chain transfer agent or the like can be used. that time,
Other monomers copolymerizable with the fatty acid vinyl ester that can be used include, for example, olefins having 5 or more carbon atoms, acrylic acid, methacrylic acid, crotonic acid, polymerizable monocarboxylic acids such as isocrotonic acid, Maleic acid, fumaric acid, polymerizable dicarboxylic acids such as itaconic acid, polymerizable dicarboxylic anhydride such as maleic anhydride,
Esters and salts of polymerizable monocarboxylic acids and polymerizable dicarboxylic acids, acrylamide, methacrylamide, t
Polymerizable acid amides such as -butyl acrylamide and N-methylol acrylamide; acrylates such as methyl acrylate, ethyl acrylate and butyl acrylate; methacrylates such as methyl methacrylate, ethyl methacrylate and butyl methacrylate , Vinyl halides such as vinyl chloride and vinyl fluoride, vinylidene halides such as vinylidene chloride and vinylidene fluoride, monomers having a glycidyl group such as allyl glycidyl ether and glycidyl methacrylate, methyl vinyl ether and n-propyl Vinyl ethers such as vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, dodecyl vinyl ether and stearyl vinyl ether; and nitriles such as acrylonitrile and methacrylonitrile. , Allyl acetate, allyl chloride, allyl compounds such as polyoxyethylene allyl ether, vinyl silyl compounds such as vinyltrimethoxysilane, although such isopropenyl acetate and the like, not limited to this.

Examples of the chain transfer agent for modifying the terminal of the polymer include, but are not limited to, aldehydes, mercaptans, halogen-containing compounds, and sulfone group-containing compounds.

In addition, the obtained PVA-based resin is subjected to a reaction such as acetalization, urethanization, etherification, grafting, phosphoric esterification, cationization, or acetoacetylation within a range not to impair the effects of the present invention. Denatured ones may be used.

The PVA resin used in the present invention may be used alone, or two or more of them may be used if necessary.

The polyfunctional epoxy compound used as the component (B) in the present invention is a compound having two or more epoxy groups in the molecule represented by the following chemical formula, for example, ethylene glycol diglycidyl ether, Trimethylolpropane triglycidyl ether, neopentyl glycol diglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether, polypropylene glycol diglycidyl ether,
Examples include diethylene glycol diglycidyl ether, sorbitol polyglycidyl ether, and the like.Other than these, a polymer or the like having a monomer having an epoxy group such as glycidyl acrylate or glycidyl methacrylate as a polymerization or copolymerization component is also included. Not exclusively. Among them, ethylene glycol diglycidyl ether is preferable because it has a small epoxy equivalent (molecular weight equivalent to one equivalent of an epoxy group) and high reactivity with a PVA-based resin.

[0017]

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The amount of the polyfunctional epoxy compound (B) used in the present invention is 0.5 to 30 parts by weight, preferably 1 to 20 parts by weight, based on 100 parts by weight of the PVA resin. . If the addition amount of the polyfunctional epoxy compound is less than 0.5 parts by weight, the purpose of water resistance cannot be achieved, and even if the addition amount is more than 30 parts by weight, the water resistance effect does not change. In some cases, properties of PVA such as excellent film forming properties and film strength may be impaired.

Examples of the polyvalent metal salt (C) used in the present invention include salts of aluminum, titanium, zirconium, magnesium and the like.
Aluminum sulfate, ammonium sulfate, aluminum acetate, aluminum chloride, aluminum fluoride, aluminum hydroxide, aluminum lactate, aluminum laurate, aluminum nitrate, aluminum oxide, aluminum perchlorate, aluminum phosphate, potassium aluminum sulfate, sodium aluminum sulfate,
Aluminum salts such as aluminum stearate, aluminum thiodiglycolate, aluminum trifluoride, trimethyl aluminum, aluminum isopropoxide and aluminum ethoxide, and an acidic aqueous solution of aluminum, titanium chloride, titanium boride, titanium silicide, Titanium ethoxide, titanium 2-ethyl-1-hexanolate, titanium hydride, titanium iodide, titanium oxide,
Titanium salts such as potassium titanium fluoride, potassium potassium oxalate, titanium sulfate, titanium tetrabutoxy, and titanium tetraisopropoxide, and an acidic aqueous solution of titanium,
Zirconium chloride, zirconium carbide, zirconium diboride, zirconium chloride, zirconium acetylacetonate, zirconium disilicide, zirconium hydride, zirconium oxide, zirconium iodide, zirconium oxychloride, zirconium n-propoxide, zirconium tetrachloride, Zirconium salts such as zirconium nitrate and acidic aqueous solutions of zirconium, magnesium acetate, magnesium bromide, magnesium carbonate, magnesium chloride, magnesium citrate, magnesium ethoxide, magnesium fluoride, magnesium hydroxide, magnesium lactate, magnesium myristate, nitric acid Magnesium, magnesium oxalate, magnesium oxide, magnesium perchlorate, magnesium phosphate, magnesium sulfate, mug silicate Magnesium salts such as Siumu, and the like acidic aqueous solution of magnesium, but is not limited thereto. Among them, a water-soluble polyvalent metal salt has a high effect, and aluminum sulfate is particularly preferred.

The amount of the polyvalent metal salt (C) used in the present invention is based on 100 parts by weight of the PVA resin.
It is 0.5 to 20 parts by weight, preferably 1 to 15 parts by weight. When the addition amount of the polyvalent metal salt is less than 0.5 parts by weight, the water resistance at room temperature drying, which is the object of the present invention, cannot be achieved, and when the addition amount is more than 20 parts by weight, Conversely, the water resistance may be reduced, and the properties of PVA such as excellent film forming properties and film strength may be impaired.

The composition of the present invention is prepared as a mixed aqueous solution, and the reaction is completed at the stage when moisture is removed by drying, and a resin composition exhibiting water resistance is obtained. As a method for preparing a mixed aqueous solution, an aqueous solution of (A) a PVA-based resin, (B) a polyfunctional epoxy compound, and (C) a polyvalent metal salt is prepared in advance and prepared by mixing the respective aqueous solutions. But (A) a PVA-based resin, (B) a polyfunctional epoxy compound, (C) a polyvalent metal salt,
And water, and stirred and dissolved at a temperature of about 90 ° C. to prepare the above (A), (B)
The order of adding (C) and (C) to the dissolution tank is not particularly limited.

The aqueous mixed solution of the composition of the present invention may contain, if necessary, a water-soluble resin other than the PVA resin, a water-dispersible resin, or an inorganic filler, a plasticizer, a pH adjuster and a polyfunctional epoxy compound. Can be used in combination.

Other water-soluble resins or water-dispersible resins that can be used in combination include albumin, gelatin, casein, starch, gum arabic, methylcellulose, and the like.
Cellulose derivatives such as hydroxyethylcellulose, polyamide resins, melamine resins, N-substituted or unsubstituted (meth) acrylamide-modified PVA, sodium poly (meth) acrylate, sodium alginate, water-soluble polyester, polyethyleneimine, polyvinylamine, polyallylamine, Polyallylamine sulfone copolymer or their aluminum salts, cationized starch,
Cationized poly (meth) acrylamide, cationized polyamide resin, SBR latex, NBR latex,
Examples include, but are not limited to, vinyl acetate emulsions, ethylene / vinyl acetate copolymer emulsions, (meth) acrylic ester emulsions, and vinyl chloride emulsions.

When these water-soluble resins or water-dispersible resins are used in combination with the PVA resin, the polyfunctional epoxy compound and the polyvalent metal salt used in the present invention, the amount added is 100 parts by weight of the PVA resin. Used in an amount of 500 parts by weight or less, preferably 300 parts by weight or less.

Inorganic fillers that can be used in combination in the present invention include silica, clay, talc, diatomaceous earth, zeolite, calcium carbonate, alumina, zinc oxide, and satin white. In this case, the ratio of the PVA-based resin / filler is usually 1/100 to 100/1,
Preferably it is selected from the range of 5/100 to 100/5.

Examples of the plasticizer which can be used in the present invention include glycerin, sorbitol and dibutyl phthalate. Examples of the pH adjuster include various acidic substances such as hydrochloric acid and sulfuric acid, sodium hydroxide, ammonia and diamine compounds. Various basic substances and the like can be mentioned, and as a crosslinking agent other than the polyfunctional epoxy compound, a dialdehyde compound and the like can be mentioned, and these can be blended within a range that does not impair the effects of the present invention.

The resin composition of the present invention is useful for applications requiring high water resistance, such as paper coating agents, various binders, adhesives, emulsifying and dispersing agents, fiber sizing agents, surface treatment agents, films and the like. Among them, it is useful as a paper coating agent.

When the resin composition of the present invention is used as a paper coating agent, an aqueous solution of the resin composition of the present invention is applied by a commonly used method such as an air knife coater, a roll blade coater, and a doctor blade coater. After coating on general quality paper, water-repellent paper, thermal paper, pressure-sensitive paper, transfer paper, rust-proof paper, release paper, colored paper, glossy paper, art paper, coated paper, paperboard, cardboard paper, etc. Used after drying. The coating amount is generally 0.1 to 50 g / dry weight.
It is a m ² approximately, but the invention is not particularly limited thereto, is determined according to the intended use.

The resin composition of the present invention comprising a PVA-based resin, a polyfunctional epoxy compound, and a polyvalent metal salt has a high degree of film obtained by drying at room temperature in spite of a long pot life in an aqueous solution. Although the reason for having water resistance is not fully understood, the reaction between the hydroxyl group of the PVA-based resin and the epoxy group of the polyfunctional epoxy compound does not react under the condition of a relatively low concentration of an aqueous solution, and the drying proceeds. It is considered that the reaction occurs under the concentrated condition to form a crosslinked structure. At that time, the polyvalent metal salt is considered to act catalytically, and in the absence of the polyvalent metal salt, it is considered that no reaction occurs even if concentrated.

[0030]

The present invention will be described below in more detail with reference to examples. The obtained resin composition was evaluated according to the following criteria. . Water resistance (water resistance test of film) A mixed aqueous solution of the resin composition was cast on a sheet made of polyethylene terephthalate and dried at 20 ° C. and 65% RH for 4 days to prepare a cast film having a thickness of 100 μ. The hot water insoluble content was measured as described above. The sample (dry weight W ₁ ) was immersed in hot water at 95 ° C. for 1 hour to dissolve the soluble components, the insoluble residue was dried at 105 ° C., and its weight W ₂
Was measured and calculated by the following equation (1). Hot water insoluble content (%) = (W ₂ / W ₁ ) × 100 (1)

[0031] Water resistance (Water resistance test of coated paper) A 5% aqueous solution of the resin composition was coated on a high quality paper of 50 g / m ² using a wire bar so that the coating amount after drying was 1 g / m ^2. And dried at 50 ° C. using a drying drum to obtain a coated paper. After the coated paper was immersed in water at 20 ° C. for 24 hours, a water resistance test was performed to determine the degree of dissolution of the coated material by rubbing with a finger. 〇: No stickiness. X: There is much stickiness. Or, the coating is eluted.

[0032] Viscosity Stability Test of Aqueous Solution The aqueous solution of the resin composition was allowed to stand at 30 ° C. for 2 months, and the change in viscosity of the aqueous solution was examined to determine whether or not the aqueous solution was gelled. 〇: No thickening or gelation of the solution occurred. ×: The solution is thickened. Or it is gelled.

[0033] Comprehensive evaluation ：: The viscosity stability of the aqueous solution is excellent, and the water resistance is very excellent. 〇: Both viscosity stability and water resistance of the aqueous solution are at practical levels. ×: Either or both of the viscosity stability and the water resistance of the aqueous solution have not reached the practical level.

Synthesis Example 1 472 parts by weight of vinyl acetate and 295 parts by weight of methanol were charged into a flask equipped with a stirrer, a thermometer, a dropping funnel and a reflux condenser. Was heated to 60 ° C. 2,2'-
1 part by weight of azobisisobutylylonitrile is added to methanol 5
A solution dissolved in 0 parts by weight was added to initiate polymerization. 5 hours after the initiation of polymerization, diacetone acrylamide 4
A solution in which 5 parts by weight of methanol was dissolved in 35 parts by weight of methanol was dropped at a constant rate, and after 6 hours, m-dinitrobenzene was added as a polymerization inhibitor to terminate the polymerization. The polymerization yield is 88
%Met. The remaining vinyl acetate was distilled off while adding metalnol vapor to the obtained reaction mixture to obtain a 50% methanol solution of a vinyl acetate polymer containing a diacetone acrylamide copolymer component. To 500 parts by weight of this mixture, 50 parts by weight of methanol and 10 parts by weight of a 4% methanol solution of sodium hydroxide were added and mixed well.
To perform a saponification reaction. The obtained gel was pulverized, washed well with methanol, and then dried to obtain a PVA resin obtained by copolymerizing and modifying diacetone acrylamide. The degree of modification of diacetone acrylamide units of this resin is 5.
0 mol%, the degree of polymerization was 1680, and the degree of saponification was 98.
It was 4 mol%.

Synthesis Example 2 In a pressurized reaction vessel equipped with a stirrer, thermometer, nitrogen inlet, ethylene inlet and initiator inlet, vinyl acetate 50 was added.
After 0 parts by weight and 95 parts by weight of methanol were charged and the inside of the system was replaced with nitrogen, the internal temperature was raised to 60 ° C. Ethylene was charged into this system so that the pressure in the reaction tank became 5 kg / cm ² , and 2,2′-azobis (4-methoxy-2,4
A solution of 0.2 part by weight of (dimethylvaleronitrile) dissolved in 10 parts by weight of methanol was injected to initiate polymerization. During the polymerization, ethylene was introduced and the pressure in the reaction vessel was increased to 5 kg /
maintained cm ^2, 2,2'-azobis (4-methoxy -
A solution of 0.8 part by weight of 2,4-dimethylvaleronitrile) dissolved in 40 parts by weight of methanol was added at a constant rate,
Six hours later, when the polymerization yield reached 48%, the reaction tank was cooled to stop the polymerization. Further, the reaction vessel was returned to normal pressure, nitrogen gas was bubbled through to completely remove ethylene, and residual vinyl acetate was distilled off while adding methanol vapor to the obtained reaction mixture, and acetic acid containing an ethylene copolymer component was removed. A 50% methanol solution of the vinyl polymer was obtained. To 500 parts by weight of this mixture, 50 parts by weight of methanol and 10 parts by weight of a 4% methanol solution of sodium hydroxide were added and mixed well, and a saponification reaction was carried out at 40 ° C. The obtained gel was pulverized, washed well with methanol, and dried to obtain a PVA-based resin in which ethylene was copolymerized and modified. The modification degree of ethylene unit of this resin was 4.0 mol%, the polymerization degree was 1660, and the saponification degree was 98.2 mol%.

Example 1 PVA 10 having a polymerization degree of 1700 and a saponification degree of 98.5 mol%
10 parts by weight of ethylene glycol diglycidiether and 5 parts by weight of aluminum sulfate were added to an aqueous solution prepared by dissolving 0 parts by weight of water in 900 parts by weight of water, and stirred at room temperature to completely dissolve the aluminum sulfate. Water was added to prepare a 5% concentration mixed aqueous solution.

When this aqueous solution was left at 30 ° C., the solution viscosity was stable for two months, and no gelation occurred. In the water resistance test of the cast film, the hot water insoluble content of the obtained film was 89.5%. In the water resistance test of the coated paper, no stickiness was observed on the surface. The properties were good. Table 1 shows the results.

Example 2 A PVA-based resin was prepared with a degree of polymerization of 550 and a degree of saponification of 88.1 mol%.
Concentration of 5 in the same manner as in Example 1 except that the PVA was changed to
% Of the mixture was prepared. When this aqueous solution was left at 30 ° C., the solution viscosity was stable for two months, and no gelation occurred. In the water resistance test of the cast film, the hot water insoluble content of the obtained film was 84.2%. In the water resistance test of the coated paper, no stickiness was observed on the surface. Was good. Table 1 shows the results.

Example 3 A mixed solution having a concentration of 5% was prepared in the same manner as in Example 1 except that the PVA resin was changed to PVA having a polymerization degree of 1010 and a saponification degree of 95.4 mol%. When this aqueous solution was left at 30 ° C., the solution viscosity was stable for two months, and no gelation occurred. In the water resistance test of the cast film, the hot water insoluble content of the obtained film was 86.8%. In the water resistance test of the coated paper, no stickiness was observed on the surface. The properties were good. Table 1 shows the results.

Example 4 A mixed solution having a concentration of 5% was prepared in the same manner as in Example 1, except that 10 parts by weight of ethylene glycol diglycidyl ether was changed to 20 parts by weight of glycerol triglycidyl ether as a polyfunctional epoxy compound. This aqueous solution
Upon standing at 0 ° C., the solution viscosity was stable for 2 months and no gelling occurred. In the water resistance test of the cast film, the hot water insoluble content of the obtained film was 82.4%. In the water resistance test of the coated paper, no stickiness was observed on the surface. The properties were good. Table 1 shows the results.

Example 5 A mixed solution having a concentration of 5% was prepared in the same manner as in Example 1 except that the addition amount of ethylene glycol diglycidyl ether was changed from 10 parts by weight to 3 parts by weight as the polyfunctional epoxy compound. When this aqueous solution was left at 30 ° C., the solution viscosity was stable for two months, and no gelation occurred. In the water resistance test of the cast film, the hot water insoluble content of the obtained film was 75.5%. In the water resistance test of the coated paper, no stickiness was observed on the surface. The properties were good. The results are shown in Table 1.

Example 6 A mixed solution having a concentration of 5% was prepared in the same manner as in Example 1 except that the addition amount of aluminum sulfate was changed from 5 parts by weight to 2 parts by weight as a polyvalent metal salt. When this aqueous solution was left at 30 ° C., the solution viscosity was stable for two months, and no gelation occurred. In the water resistance test of the cast film, the hot water insoluble content of the obtained film was 85.9%.
Further, in the water resistance test of the coated paper, no stickiness was observed on the surface, and in each case, the water resistance was good. Table 1 shows the results.

Example 7 A mixed solution having a concentration of 5% was prepared in the same manner as in Example 1 except that 5 parts by weight of aluminum sulfate was changed to 15 parts by weight of aluminum aluminum sulfate as a polyvalent metal salt. When this aqueous solution was left at 30 ° C., the solution viscosity was stable for two months, and no gelation occurred. In the water resistance test of the cast film, the hot water insoluble content of the obtained film was 84.6%. In the water resistance test of the coated paper, no stickiness was observed on the surface. The properties were good. Table 1 shows the results.

Example 8 The degree of polymerization was 1700 and the degree of saponification was 98.
Instead of 5 mol% of PVA, the diacetone acrylamide copolymerized modified PVA resin obtained in Synthesis Example 1 (modification degree: 5.0 mol%, polymerization degree: 1680, saponification degree: 98.4 mol%) was used. A mixed solution having a concentration of 5% was prepared in the same manner as in Example 1 except for the above. When this aqueous solution was left at 30 ° C., the solution viscosity was stable for two months, and no gelation occurred. In the water resistance test of the cast film, the hot water insoluble content of the obtained film was as high as 93.2%. In the water resistance test of the coated paper, no stickiness was observed on the surface. Also had good water resistance. Table 1 shows the results.

Example 9 As a PVA-based resin, the polymerization degree was 1700 and the saponification degree was 98.
Instead of using 5 mol% of PVA, the ethylene copolymer modified PVA resin obtained in Synthesis Example 2 (modification degree 4.0 mol%, polymerization degree 1660, saponification degree 98.2 mol%) was used. In the same manner as in Example 1, a mixed solution having a concentration of 5% was prepared.
When this aqueous solution was left at 30 ° C., the solution viscosity was stable for two months, and no gelation occurred. Further, in the water resistance test of the cast film, the hot water insoluble content of the obtained film was as high as 92.5%, and in the water resistance test of the coated paper, no stickiness was observed on the surface. Also had good water resistance. Table 1 shows the results.

Comparative Example 1 A mixture having a concentration of 5% was prepared in the same manner as in Example 1 except that ethylene glycol diglycidyl ether was not added. When this aqueous solution was left at 30 ° C., the solution viscosity was stable for two months, and no gelation occurred. However, in the water resistance test of the cast film, the film was completely dissolved in hot water and the insoluble content was 0.0%. In the water resistance test of the coated paper, the coating film was completely eluted, Sex was very low. Table 1 shows the results.

Comparative Example 2 A mixed solution having a concentration of 5% was prepared in the same manner as in Example 1 except that aluminum sulfate was not added. 30 ℃
, The solution viscosity was stable for 2 months and no gelation occurred. However, in the water resistance test of the cast film, the film was dissolved in hot water, the insoluble content was 0.0%, and in the water resistance test of the coated paper,
Part of the coating film was eluted, stickiness was observed on the surface, and water resistance was low. Table 1 shows the results.

Comparative Example 3 The amount of ethylene glycol diglycidyl ether added was 1
Except having changed from 0 weight part to 0.5 weight part, it carried out similarly to Example 1, and produced the liquid mixture of 5% density | concentration. When this aqueous solution was left at 30 ° C., the solution viscosity was stable for two months, and no gelation occurred. However, in the water resistance test of the cast film, the film was completely dissolved in hot water and the insoluble content was 0.0%. In the water resistance test of the coated paper, the coating film was completely eluted, Sex was very low. Table 1 shows the results.

Comparative Example 4 The amount of ethylene glycol diglycidyl ether added was 1
Except having changed from 0 weight part to 40 weight part, it carried out similarly to Example 1, and produced the liquid mixture of 5% density | concentration. This aqueous solution
Upon standing at 0 ° C., the solution viscosity was stable for 2 months and no gelling occurred. However, the cast film obtained from the mixed solution was brittle, and cracks and the like of the coating film occurred when preparing a coated paper. It is not something that can be used practically as a film or coating,
The water resistance test could not be performed. Table 1 shows the results.

Comparative Example 5 A mixture having a concentration of 5% was prepared in the same manner as in Example 1 except that the amount of aluminum sulfate was changed from 5 parts by weight to 0.2 parts by weight. When this aqueous solution was left at 30 ° C.,
The solution viscosity was stable for 2 months and no gelling occurred. In the water resistance test of the cast film, the hot water insoluble content of the obtained film was as low as 32.8%. In the water resistance test of the coated paper, the surface was sticky, and the water resistance was low. Was. Table 1 shows the results.

Comparative Example 6 A mixture having a concentration of 5% was prepared in the same manner as in Example 1 except that the amount of aluminum sulfate was changed from 5 parts by weight to 30 parts by weight. When this aqueous solution was left at 30 ° C., the solution viscosity was stable for two months, and no gelation occurred. However, the cast film obtained from the mixed solution was brittle, and cracks and the like of the coating film occurred when preparing a coated paper. Each of them was not practically usable as a film or a coating film, and could not be subjected to a water resistance test. Table 1 shows the results.

[0052]

[Table 1]

[0053]

According to the present invention, a resin composition having good viscosity stability in an aqueous solution state, excellent workability, and exhibiting excellent water resistance even when dried at a relatively low temperature. And a paper coating agent using the same.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) D21H 19/24 D21H 19/24 C 21/16 21/16 // (C08L 29/04 (C08L 29/04) 63:00) 63:00) A-F term (reference) 4J002 BE021 BE031 CD002 CD012 CD192 DB016 DD036 DD066 DD076 DD086 DE096 DE136 DE146 DE196 DE236 DF036 DG046 DH046 DJ006 DK006 EC076 EE046 EG036 EG046 EZ006 FD010 FD010 FD00 GH00 GJ01K00 HA106 HA166 HA336 HA376 HA416 JC38 KA08 KA10 MA08 NA04 NA24 NA25 PA18 PB02 PB05 PC10 4L055 AG08 AG59 AG64 AG73 AG88 AG89 AH23 AJ03 BE08 EA32 FA19 FA22 FA30 GA05 GA06 GA12 GA13 GA14 GA17 GA19 GA43 GA47

Claims (6)

[Claims] (A) a polyvinyl alcohol resin 10
(B) polyfunctional epoxy compounds 1 to 3 based on 0 parts by weight
A resin composition comprising 0 parts by weight and (C) 0.5 to 20 parts by weight of a polyvalent metal salt. 2. The resin composition according to claim 1, wherein the polyfunctional epoxy compound (B) is ethylene glycol diglycidyl ether. 3. The resin composition according to claim 1, wherein the polyvalent metal salt (C) is aluminum sulfate. 4. The resin composition according to claim 1, wherein (A) the polyvinyl alcohol resin is a polyvinyl alcohol resin obtained by copolymerizing and modifying diacetone acrylamide. 5. The resin composition according to claim 1, wherein (A) the polyvinyl alcohol resin is a polyvinyl alcohol resin obtained by copolymerizing and modifying an α-olefin having 4 or less carbon atoms. 6. A paper coating agent comprising an aqueous solution of the resin composition according to claim 1 as a main component.