JPH10219218A - Adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aqueous adhesive excellent in preservation stability, adhesive strength and water resistance and good in initial adhesion by including a specific aqueous emulsion and polyfunctional isocyanate compound. SOLUTION: This aqueous adhesive is obtained by formulating (A) an aqueous emulsion including (i) modified polyvinyl alcohol having a primary or secondary amino group in the molecule as a dispersant and (ii) a polymer of an ethylenically unsaturated monomer and/or a dienic monomer as a dispersoid and obtained by carrying out an emulsion (co)polymerization of the component (ii) in the presence of the component (i) in an aqueous medium, with (B) a polyvalent isocyanate compound (e.g. tolylenediisocyanate) in a weight ratio (solid ratio) of (99/1) to (10/90). Further, the proportion of the dispersant is preferably 1-200 parts weight based on 100 parts weight of the dispersoid. The component (i) is obtained, for example, by copolymerizing the ethylenically unsaturated monomer having a primary or secondary amino group with vinyl acetate, and saponifying the obtained copolymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an aqueous adhesive. More specifically, it relates to an aqueous adhesive excellent in storage stability, initial adhesiveness, adhesive strength, water resistance and the like.

[0002]

2. Description of the Related Art Unlike a conventional aminoplast adhesive, an adhesive containing a water-soluble polymer, an aqueous emulsion and an isocyanate compound as main components does not generate formalin, and is pressed at room temperature for a relatively short time. Alone, extremely high adhesive strength and water resistance can be obtained, so that it has been awarded as an adhesive for wood (for example, JP-A-48-947).
39, 50-69139). Further, as the same adhesive, an aqueous adhesive composition comprising a copolymer emulsion of a hydroxyl group-containing monomer such as allyl alcohol, 2-hydroxyethyl acrylate, N-methylolated acrylamide and vinyl acetate, and a divalent isocyanate compound (JP-A-49-26346), a polyvinyl acetate emulsion using polyvinyl alcohol as a dispersant (protective colloid) and a water-resistant adhesive composition comprising a polyvalent isocyanate compound (JP-A-3-33178)
Publication). Additionally, the emulsion polymer comprises an emulsion polymer stabilized with polyvinyl alcohol, the first step producing a vinyl acetate copolymer having a glass transition temperature in the range of 10 to 40 ° C, and the second step comprising 50 to 120 ° C. Adhesives produced by a two-stage polymerization process comprising producing a methyl methacrylate copolymer having a glass transition temperature of 0 ° C., wherein the ratio of vinyl acetate copolymer to methyl methacrylate copolymer ranges from 10: 1 to 10: 6. (JP-A-2-302485). Under these circumstances, JIS has recently been established for wood adhesives comprising an aqueous polymer and an isocyanate compound.

In recent years, as the number of objects to be bonded has been expanded, it has become necessary to improve the level of bonding performance. In particular,
Structural adhesives may be required to have higher durability, and individual applications may be required to further improve initial adhesiveness. In the latter case, when an aqueous emulsion of a vinyl acetate resin containing polyvinyl alcohol (hereinafter abbreviated as PVA) as a dispersant is frequently used, there is a problem that the initial adhesion is improved but the water resistance is not sufficient. In addition, PVA, which is an aqueous polymer blended in this type of adhesive, also greatly contributes to the performance of the adhesive. Specifically, complete saponification or P having an acetoacetyl group
Although the use of VA improves the water resistance, the aqueous emulsion and P
There is a problem that the low-temperature viscosity stability and the storage stability of the main agent composed of VA are reduced. In addition, the conventional adhesives as described above exhibit some performance, but those having satisfactory performance in all respects of viscosity stability, initial adhesiveness, adhesive strength and water resistance of the main agent are not available. It has not been developed yet.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide an aqueous adhesive having excellent storage stability, adhesive strength and water resistance, and good initial adhesiveness. Is what you do.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, a modified polyvinyl alcohol having a primary amino group or a secondary amino group in a molecule is used as a dispersant, and ethylene is used. Aqueous emulsion (A) containing a polymer comprising at least one unsaturated monomer unit selected from the group consisting of unsaturated unsaturated monomers and diene monomers, and an adhesive comprising a polyvalent isocyanate compound (B) And completed the present invention.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION As a dispersant, a modified PV having a primary amino group or a secondary amino group in a molecule to be used is used.
If it is A, there is no particular limitation. Modified P having this functional group
VA can be obtained by various methods, and the method is exemplified below. (1) An ethylenically unsaturated monomer having a primary amino group or a secondary amino group, or an ethylenically unsaturated monomer having a functional group capable of forming a primary amino group or a secondary amino group by hydrolysis or the like And saponification after copolymerizing with vinyl acetate. (2) A mercaptan having an amino group is subjected to an addition reaction with a mercaptan having an amino group as a catalyst using NaOH or the like as a catalyst, followed by saponification, with a monomer having an epoxy group such as allyl glucidyl ether and an epoxy group in a side chain of a polymer composed of vinyl acetate. Method. (3) A method in which a compound having a functional group capable of reacting with a hydroxyl group of PVA in a molecule and having a primary amino group or a secondary amino group is reacted with PVA. (4) A method of polymerizing an ethylenically unsaturated monomer having a primary amino group or a secondary amino group in the presence of PVA having a mercapto group. According to this method, a PVA-based block polymer is obtained.

A modified PV having at least one functional group selected from a primary amino group and a secondary amino group in a molecule.
A may have a functional group other than a primary amino group or a secondary amino group in the molecule. Such monomer units include ethylene, isobutylene, acrylonitrile, methacrylonitrile, acrylic acid, methacrylic acid, (anhydrous) fumaric acid, (anhydrous) maleic acid, (anhydrous)
Itaconic acid, allylsulfonic acid, methallylsulfonic acid,
Vinyl sulfonic acid, acrylamide-2-methylpropanesulfonic acid, methacrylamide-2-methylpropanesulfonic acid, sulfopropyl acrylate, sulfopropyl methacrylate and their alkali salts, acrylamide, methacrylamide, trimethyl- (3-acrylamide- 3-dimethylpropyl) -ammonium chloride, ethyl vinyl ether, butyl vinyl ether, N
-Vinylpyrrolidone, vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, vinylidene fluoride, tetrafluoroethylene and the like. Further, those having a functional group at the terminal obtained by polymerizing a vinyl ester monomer such as vinyl acetate in the presence of a thiol compound such as thiolacetic acid or mercaptopropionic acid may be used.

[0008] The content of the primary amino group or the secondary amino group in the modified PVA used in the present invention is preferably 0.1 to 30 mol% as a monomer unit containing the functional group, and 0.5 to 30 mol%. 25 mol% is more preferred. If the content of the functional group is less than 0.1 mol%, the effect may not be sufficiently exhibited, while if it exceeds 30 mol%, the inherent properties of PVA may not be sufficiently exhibited. Modified PVA
Is preferably 100 or more, and 200 to 8000.
Is more preferred. The degree of saponification of the modified PVA is not particularly limited, but is preferably 50 mol% or more, and preferably 80 to 99.9.
Molar% is more preferred.

The dispersoid of the aqueous emulsion constituting the aqueous adhesive of the present invention comprises one or more unsaturated monomer units selected from ethylenically unsaturated monomers and diene monomers ( (Co) polymer.

Examples of the ethylenically unsaturated monomers include olefins such as ethylene, propylene and isobutene, halogenated olefins such as vinyl chloride, vinylidene chloride, vinyl fluoride and vinylidene fluoride, vinyl formate, vinyl acetate and propion. Vinyl esters such as vinyl acrylate, vinyl versatate and vinyl pivalate, acrylic acid, methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate Acrylates such as t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate, hydroxypropyltrimethylammonium acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, methacrylic acid Le acid n- propyl methacrylate i- propyl, n- butyl methacrylate, i- butyl methacrylate, t- butyl methacrylate, 2
Methacrylates such as ethylhexyl, dodecyl methacrylate, octadecyl methacrylate, hydroxypropyltrimethylammonium methacrylate, acrylamide, methacrylamide, N-methylolacrylamide, N, N-dimethylacrylamide, acrylamide-2-methylpropanesulfonic acid And its sodium salt acrylamide, trimethyl-
(3-acrylamido-3-dimethylpropyl) -ammonium chloride, 3-acrylamidopropyltrimethylammonium chloride, 3-methacrylamidopropyltrimethylammonium chloride, N-methylacrylamide, N-ethylacrylamide, diacetoneacrylamide, acrylonitrile, methacrylonitrile Nitriles, such as allyl acetate, allyl compounds such as allyl chloride, styrene, α-methylstyrene, P-methylstyrenesulfonic acid and styrene-based monomers such as sodium and potassium salts thereof, and other N-vinylpyrrolidone. And diene monomers include butadiene, isoprene, chloroprene and the like.

The aqueous emulsion in the aqueous adhesive of the present invention uses a modified PVA having a primary amino group or a secondary amino group in a molecule as a dispersant, and is selected from ethylenically unsaturated monomers and diene monomers. There is no particular limitation as long as a (co) polymer composed of one or more unsaturated monomer units is used as a dispersoid, and an ethylenically unsaturated monomer and a diene-based monomer may be used in the presence of the modified PVA. An aqueous emulsion obtained by emulsifying (co) polymerizing one or more unsaturated monomers selected from monomers in an aqueous medium, or a conventionally known PVA-based polymer or water-soluble cellulose-based polymer , Anionic, nonionic, cationic or amphoteric surfactants as dispersion stabilizers and one or more unsaturated monomers selected from ethylenically unsaturated monomers and diene monomers. The aqueous emulsion of the monomer was added the modified PVA in the emulsion (co) aqueous emulsion obtained by polymerizing in an aqueous medium can be used.

In carrying out the emulsion polymerization for obtaining the above-mentioned aqueous emulsion, a usual emulsion polymerization method in which the above-mentioned monomer is added temporarily or continuously, followed by heating and stirring can be carried out. Alternatively, a method in which a monomer previously mixed and emulsified with an aqueous dispersant solution may be continuously added.

The amount of the dispersant used is preferably 1 to 200 parts by weight, more preferably 2 to 100 parts by weight, per 100 parts by weight of the dispersoid. If the amount of the dispersant is less than 1 part by weight or more than 200 parts by weight, the water-resistant adhesive strength may not be sufficiently exhibited.

The aqueous emulsion used in the present invention comprises:
The above aqueous emulsion may be used alone as it is, but if necessary, conventionally known polyvinyl acetate emulsion, ethylene-vinyl acetate copolymer emulsion,
A (meth) acrylate polymer emulsion, a styrene-butadiene copolymer emulsion, an epoxy emulsion, a urethane emulsion, or the like can be added as long as the effects of the present invention are not impaired.

The polyvalent isocyanate compound (B) used in the present invention has two or more isocyanate groups in the molecule. Examples thereof include tolylene diisocyanate (TDI); hydrogenated TDI; and trimethylolpropane. TDI adduct (for example, manufactured by Bayer AG, trade name:
Desmodur L); triphenylmethane triisocyanate; methylenebisdiphenyl isocyanate (MDI); hydrogenated MDI; polymerized MDI; hexamethylene diisocyanate; xylylene diisocyanate;
4,4-dicyclohexylmethane diisocyanate; isophorone diisocyanate, and the like. In addition, a prepolymer having a terminal group having an isocyanate group, which is previously polymerized with an excess of polyisocyanate in a polyol, may be used.

The adhesive of the present invention is obtained by blending a polyisocyanate compound (B) with a main ingredient mainly composed of an aqueous emulsion (A). The mixing ratio of the aqueous emulsion (A) and the polyvalent isocyanate compound (B) is preferably in the range of (A) / (B) = 99/1 to 10/90 (weight ratio) in terms of solid content ratio, and is preferably 95/5 to 5/5. A range of 20/80 is more preferred. When the amount of the polyvalent isocyanate compound is less than this range, the adhesive strength and the water resistance are reduced. On the other hand, if it exceeds this range, the pot life after blending the polyvalent isocyanate is shortened, and the practicality is reduced.

In the adhesive of the present invention, if necessary, various polyvinyl alcohols, starch, modified starch, oxidized starch, sodium alginate, carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, maleic anhydride-isobutene copolymer, anhydrous Water-soluble polymer compounds such as maleic acid-styrene copolymer and maleic anhydride-methyl vinyl ether copolymer, and urea-formalin resin, urea-melamine-formalin resin, phenol-formalin resin, etc., are generally used as adhesives. Can be used as appropriate. Further, the adhesive of the present invention includes fillers such as clay, kaolin, talc, calcium carbonate, and wood flour; fillers such as flour; reaction accelerators such as boric acid and aluminum sulfate; pigments such as titanium oxide; Various additives such as a preservative and a rust preventive can be added as needed.

The adhesive of the present invention is used for bonding various adherends, and is particularly suitable for bonding wood, plywood, paper, fiber, various plastics and the like. The application amount may be appropriately selected according to various situations. Examples of the coating method include coating with a brush and coating with a roll. Drying after applying the adhesive may be heating drying from room temperature to 200 ° C., but the adhesive of the present invention exhibits sufficient adhesive strength even when dried at room temperature. The feature of the adhesive of the present invention is that the storage stability of the main agent is excellent, and that both the initial adhesion and the water resistance in boiling water are excellent.

[0019]

The present invention will be described more specifically below with reference to examples and comparative examples. In Examples and Comparative Examples,
“Parts” and “%” are based on weight unless otherwise specified.

(Production Example of Aqueous Emulsion) Production Example 1 PVA containing primary amino group obtained by copolymerizing vinyl formamide and vinyl acetate and then saponifying the copolymer.
(Polymerization degree 1050, saponification degree 98.5 mol%, primary amino group content 3.0 mol%)
The PVA was heated and melted at 5 ° C. An aqueous PVA solution was charged into a pressure-resistant autoclave, and 100 parts of vinyl acetate was added.
After purging with nitrogen, ethylene was injected under pressure to 40 kg / cm ² . Next, the internal temperature was raised to 60 ° C., and a 1% aqueous solution of V-50 (manufactured by Wako Pure Chemical Industries, Ltd.) was sequentially added to perform copolymerization. The copolymerization was completed in 3 hours, the solid content was 53.0%, and the viscosity was 11
A stable vinyl acetate-ethylene copolymer emulsion (emulsion (1)) of 20 mPa · s was obtained.

Production Example 2 A reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet tube and a thermometer was charged with 405 parts of vinyl acetate monomer, 11 parts of allyl glycidyl ether and 30 parts of methanol, and nitrogen gas was bubbled for 15 minutes. And degassed. Separately, an initiator solution prepared by dissolving 4.5 parts of 2,2-azoisobutyronitrile in 15 parts of methanol was prepared, and nitrogen was replaced by bubbling with nitrogen gas. Start raising the temperature of the reactor.
Then, a separately prepared initiator solution was added to initiate polymerization. Polymerization was carried out at 60 ° C. for 4 hours, and the polymerization was stopped by cooling. At this time, the solid content concentration was 54.8%. Subsequently, unreacted vinyl acetate monomer was removed while occasionally adding methanol at 30 ° C. under reduced pressure to obtain a methanol solution of polyvinyl acetate copolymer (concentration: 44.5%). This copolymer was a polyvinyl acetate copolymer containing 2.1 mol% of allyl glycidyl ether units (epoxy groups) and having a viscosity average molecular weight of 80 × 10 ³ . Next, a methanol solution of the polyvinyl acetate copolymer having an epoxy group obtained above (concentration: 44.5%) was placed in a reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer.
After 100 parts were weighed and nitrogen gas was bubbled for 15 minutes, a solution prepared by dissolving 8.0 parts of 2-aminothiophenol and 0.03 part of sodium hydroxide in 48 parts of methanol was charged. After reacting at 50 ° C. for 2 hours with stirring, 40
After cooling to ° C., 40 parts of a 10% methanol solution of sodium hydroxide was added for saponification. The mixture was allowed to stand at 40 ° C. for 5 hours, pulverized, neutralized by adding 8 parts of acetic acid, subjected to Soxhlet extraction with methanol for 48 hours, and then dried at 60 ° C. for 20 hours or more to obtain a modified polyvinyl alcohol. The modified polyvinyl alcohol has 2.1 mol% of aniline groups introduced therein and has a vinyl alcohol content of 9%.
The content was 7.0 mol% and the degree of polymerization was 1,000. Ethylene-vinyl acetate copolymer emulsion (OM-42, manufactured by Kuraray)
Aqueous emulsion (2) was prepared by adding 100 parts by weight of a 15% aqueous solution of the above-mentioned modified polyvinyl alcohol to 100 parts by weight of (00, solid content concentration 55%).

Production Example 3 3 parts of primary amino group-containing PVA (same as used in Production Example 1) and secondary amino group-containing PVA (methyl vinylacetamide and vinyl acetate were copolymerized and then saponified (polymerized 990, saponification degree 98.2 mol%, secondary amino group content 2.2 mol%) and 100 parts of water,
The PVA was heated and melted at ℃. The aqueous PVA solution was charged into a glass polymerization vessel, and 60 parts of vinyl acetate and 2-acrylic acid were added.
After adding 20 parts of ethylhexyl and 20 parts of methyl methacrylate and purging with nitrogen, the internal temperature was raised to 60 ° C., and V-5
0 (manufactured by Wako Pure Chemical Industries) was added successively to carry out copolymerization. The copolymerization was completed in 3 hours and the solid concentration was 51.8.
%, A stable vinyl acetate-2-ethylhexyl acrylate-methyl methacrylate copolymer emulsion (emulsion (3)) having a viscosity of 5000 mPa · s.

Production Example 4 PVA having a terminal mercapto group (polymerization degree 1010,
Saponification degree 98.0 mol%, mercapto group content 1.43 ×
10 ⁻⁵ eq / g) 10 parts were added to 100 parts of water, and 95 ° C.
And dissolved by heating. After adjusting the pH to 3 by adding 0.5N hydrochloric acid, allylamine hydrochloride 10 previously substituted with nitrogen is added.
Then, the temperature was raised to 60 ° C., and then an aqueous solution in which 0.05 part of V-50 (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in 5 parts of water was added to start copolymerization. The copolymerization was completed in 2 hours, and an aqueous block polymer solution of PVA and allylamine having a polymerization rate of 100% and a solid content of 16.0% was obtained. 64 parts of water was added to 31 parts of the aqueous block polymer solution, 50 parts of vinyl acetate, 25 parts of n-butyl acrylate and 25 parts of methyl methacrylate were added, and after replacement with nitrogen, 0.5 part of ammonium persulfate was added to water. Add an aqueous solution dissolved in 5 parts, and add
To start copolymerization. The copolymerization was completed in 2 hours and 30 minutes, and a stable vinyl acetate-n-butyl acrylate-methyl methacrylate copolymer emulsion (emulsion (4)) having a solid content of 50.0% and a viscosity of 1350 mPa · s was obtained. Was.

Production Example 5 4 parts of primary amino group-containing PVA (same as used in Production Example 1) and polyoxyethylene (20 mol adduct) nonylphenyl ether (Nonipol 200, manufactured by Sanyo Chemical Industries, Ltd.)
100 parts of water was added to 2 parts, and PVA and Nonipol 2 were added at 95 ° C.
00 was dissolved by heating. 10 parts of styrene and 10 parts of n-butyl acrylate were added to the aqueous solution, and after replacement with nitrogen, V
An aqueous solution in which 0.05 part of -50 (manufactured by Wako Pure Chemical Industries) was dissolved in 5 parts of water was added, and copolymerization was started at 70 ° C. Next, 4
0 parts of styrene and 40 parts of n-butyl acrylate were mixed and added sequentially to the polymerization system over 2 hours. The copolymerization was completed in 3 hours, and a stable styrene-n-butyl acrylate copolymer emulsion (emulsion (5)) having a solid content of 50.1% and a viscosity of 570 cp was obtained.

Example 1 A mixture of 35 parts of a 15% aqueous solution of partially saponified polyvinyl alcohol (PVA-217, manufactured by Kuraray) and 65 parts of calcium carbonate was added to 100 parts of the aqueous emulsion (1) of Production Example 1 to prepare a main ingredient. did. Then, 30 parts of polymethylene polyphenylisocyanate (manufactured by Nippon Polyurethane Co., Ltd., trade name: Millionate MR-100) was added thereto to prepare an adhesive. Using this, a test was performed under the following conditions. Table 1 shows the results.

[Test conditions] Stability of the main agent: Put the main agent in a closed container,
It was left in a thermostat at 5 ° C. and 40 ° C. for 2 weeks. The state before and after standing was observed. ：: no change Δ: slight increase in viscosity or sedimentation ×: no gelation or fluidity of sediment Adhesion test An adhesion test was performed using the above composition under the following conditions. Substrate: birch / birch (masa) water content 8% Coating amount: 250 g / m ² (both sides coated) Deposition time: 1 minute Pressing conditions: 20 ° C., 24 hours, pressure 10 kg / cm ² (normal strength, (Measurement of compressive shear bond strength according to JIS K-6852) Normal strength: Measured as it is after curing for 7 days at 20 ° C. Repeated boiling: After curing at 20 ° C. for 7 days, place the test specimen in boiling water for 4 days. After soaking for a period of time, it was dried in air at 60 ° C. for 20 hours, further immersed in boiling water for 4 hours, immersed in water at room temperature until cooled, and subjected to the test in a wet state. Initial adhesion: 10 kg / cm ² at 20 ° C after bonding
Pressure for 10 minutes and immediately measure the compression shear adhesive strength

Example 2 Production Example 2 in place of the aqueous emulsion (1) of Example 1
A main agent was prepared in the same manner as in Example 1 except that the aqueous emulsion (2) was used, and polymethylene polyphenylisocyanate (manufactured by Nippon Polyurethane Co., trade name: Millionate MR-100) was added thereto to prepare an adhesive. . Using this, a test was performed in the same manner as in Example 1. Table 1 shows the results.

Example 3 Production Example 3 in place of the aqueous emulsion (1) of Example 1
A main agent was prepared in the same manner as in Example 1 except that the aqueous emulsion (3) was used, and polymethylene polyphenyl isocyanate (manufactured by Nippon Polyurethane Co., trade name: Millionate MR-100) was added thereto to prepare an adhesive. . Using this, a test was performed in the same manner as in Example 1. Table 1 shows the results.

Example 4 Production Example 4 in place of the aqueous emulsion (1) of Example 1
A main agent was prepared in the same manner as in Example 1 except that the aqueous emulsion (4) was used, and polymethylene polyphenylisocyanate (manufactured by Nippon Polyurethane Co., trade name: Millionate MR-100) was added thereto to prepare an adhesive. . Using this, a test was performed in the same manner as in Example 1. Table 1 shows the results.

Example 5 Production Example 5 in place of the aqueous emulsion (1) of Example 1
A main agent was prepared in the same manner as in Example 1 except that the aqueous emulsion (5) was used, and polymethylene polyphenylisocyanate (manufactured by Nippon Polyurethane Co., trade name: Millionate MR-100) was added thereto to prepare an adhesive. . Using this, a test was performed in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 1 In place of the primary amino group-containing PVA obtained by copolymerizing vinyl formamide and vinyl acetate in Production Example 1 and then saponifying, unmodified PVA (polymerization degree 10
Aqueous emulsion (6) was produced in the same manner as in Production Example 1 except that the aqueous emulsion (6, saponification degree: 98.5 mol%) was used. A main ingredient was prepared in the same manner as in Example 1 except that the aqueous emulsion (6) was used instead of the aqueous emulsion (1) of Example 1, and polymethylene polyphenyl isocyanate (trade name: Millionate MR, manufactured by Nippon Polyurethane Co., Ltd.)
-100) was added to prepare an adhesive. Using this,
The test was performed in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 2 Comparative Example 1 was repeated except that 10 parts of unmodified PVA (polymerization degree 1050, saponification degree 88.5%) was used instead of unmodified PVA (degree of polymerization 1050, saponification degree 98.5 mol%). In the same manner as in Example 1, an aqueous emulsion (7) was obtained. A test was conducted in the same manner as in Example 1 using this emulsion. Table 1 shows the results.

[0033]

[Table 1]

[0034]

As described above, the adhesive of the present invention is excellent in the stability of the base material when left to stand, has excellent initial adhesive strength, and has remarkably improved adhesive strength and water resistance. The adhesive of the present invention can be applied to the case of bonding various kinds of materials, and can be particularly preferably used as an adhesive for wood. In addition to wood-to-wood bonding, wood and paper,
It can also be used for bonding to textiles, inorganic plates, films, etc.

Claims (1)

[Claims] 1. A modified polyvinyl alcohol having a primary amino group or a secondary amino group in a molecule as a dispersant, and at least one unsaturated monomer selected from an ethylenically unsaturated monomer and a diene monomer. An aqueous emulsion (A) having a polymer composed of units as a dispersoid and an adhesive comprising a polyvalent isocyanate compound (B).