JPH11181396A - Adhesive composition and preparation thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive compsn. excellent in adhesive strength and water resistance and to provide a process for preparing the same whereby a major component can be prepd. highly stably at a relatively low temp. at a low energy cost and in a high productivity. SOLUTION: This compsn. is a combination of a major component comprising (A) an aq. emulsion and (B) polyvinyl alcohol having a degree of saponification of 50 mol.% or higher and a cationic group content in the molecule of 0.1-20 mol.% with (C) a polyisocyanate and is prepd. by adding ingredient B to ingredient A at 60 deg.C or lower to prepare the major component and compounding therewith ingredient C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive and a method for producing the same, and more particularly, to an adhesive excellent in adhesive strength and water resistance and having high stability in producing a base material, and
The present invention relates to a method for producing an adhesive, which has a low energy cost and a high productivity because a main agent can be produced at a relatively low temperature.

[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, for extremely high adhesive strength and water resistance,
It has been awarded as an adhesive for plywood and various plastics (for example, see JP-A-48-94739, 50-90).
69139). Under these circumstances, JIS has recently been established for wood adhesives comprising an aqueous polymer and an isocyanate compound. Also, in recent years, this type of adhesive has attracted attention as an adhesive that is more friendly to the human body and the environment than amino resin-based adhesives, especially for plywood manufacturing, since there is virtually no formalin generation from the adhesive. I have.

[0003] An adhesive comprising a water-soluble polymer, an aqueous emulsion and an isocyanate compound has heretofore been used as a main ingredient mainly comprising an aqueous emulsion obtained by adding an aqueous solution obtained by heating and dissolving an aqueous polymer, polyvinyl alcohol, to an aqueous emulsion. Before use, an isocyanate compound was added as a crosslinking agent before use. However, with the expansion of production lines and the scale of production, there is an increasing need for more efficient production of main ingredients. Therefore, if the base material can be produced at a relatively low temperature, the energy cost for dissolving the water-soluble polymer into an aqueous solution is reduced, and the productivity of the adhesive base material is increased, so that the base material can be produced efficiently. Is possible. In particular, if a water-soluble polymer can be added to an aqueous emulsion and dissolved at a relatively low temperature in a short time, not only productivity and workability will be remarkably improved, but also a place where an adhesive is used, that is, on-site. A further merit arises because the adhesive can be easily compounded at the same time.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems in the prior art, and has a high stability at the time of manufacturing the main agent, and can reduce the energy cost because the main agent can be manufactured at a relatively low temperature. It is another object of the present invention to provide a method for producing an adhesive with high productivity and to provide an adhesive having excellent adhesive strength and water resistance.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies on the above-mentioned objects and found that (A) an aqueous emulsion and (B) a saponification degree of not less than 50 mol% and a cationic group having an intramolecular molecule. It has been found that an adhesive containing 0.1 to 20 mol% of polyvinyl alcohol as a main component and (C) a polyvalent isocyanate is suitable for the intended purpose. Further, (A) aqueous emulsion is added to (B) saponification degree 5
0 mol% or more and a cationic group in a molecule of 0.1 to 2
A method for producing an adhesive characterized by adding a polyvinyl alcohol having 0 mol% at a temperature of 60 ° C. or lower to prepare a main agent, and blending (C) a polyvalent isocyanate with the main agent.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION (A) Constituting the adhesive of the present invention
The aqueous emulsion contains a single or two or more kinds of conventionally known anionic, cationic, amphoteric, nonionic low molecular surfactants and various water soluble polymers (protective colloids) such as polyvinyl alcohol and hydroxyethyl cellulose as dispersants. An aqueous solution obtained by a post-emulsification method of a polymer represented by an emulsion polymerization type aqueous emulsion or a polyurethane emulsion obtained by emulsion polymerization of a radically polymerizable ethylenically unsaturated monomer and a diene monomer in an aqueous solution. Emulsions may be used alone or in combination of two or more.

The ethylenically unsaturated monomers constituting the dispersoid of the emulsion polymerization type aqueous emulsion constituting the adhesive of the present invention include olefins such as ethylene, propylene and isobutene, vinyl chloride, vinylidene chloride and fluoride. Vinyl, halogenated olefins such as vinylidene fluoride, vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, vinyl versatate, vinyl pivalate, acrylic acid, methyl acrylate, ethyl acrylate, and n-acrylic acid Propyl, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate,
Acrylic esters such as dodecyl acrylate, octadecyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxypropyl trimethylammonium acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, methacrylic acid n-propyl,
I-propyl methacrylate, n-butyl methacrylate,
I-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, hydroxypropyl methacrylate trimethylammonium chloride, etc. Methacrylic esters, acrylamide, methacrylamide, N-
Methylol acrylamide, 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-
Nitriles such as methylacrylamide, N-ethylacrylamide, diacetoneacrylamide, acrylonitrile, methacrylonitrile, allyl compounds such as allyl acetate and allyl chloride, styrene, α-methylstyrene, P-
Examples include methylstyrenesulfonic acid and styrene-based monomers such as sodium and potassium salts thereof, and other N-vinylpyrrolidone, and examples of the diene-based monomer include butadiene, isoprene, and chloroprene.

[0008] In carrying out emulsion polymerization for obtaining an emulsion polymerization type aqueous emulsion constituting the adhesive of the present invention, the above-mentioned monomer is temporarily dissolved in the presence of water, the above-mentioned dispersant and a polymerization initiator. Or adding continuously, heating,
A usual emulsion polymerization method such as stirring can be carried out, or a method in which a monomer is preliminarily mixed and emulsified with an aqueous solution of a dispersant can be continuously added. The polymerization initiator is not particularly limited and includes, for example, potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide, 2,2′-azobis (2-amidinopropane) dihydrochloride, cumene hydropar Oxide, benzoyl peroxide, isopropylbenzene peroxide or the like is used alone or in a redox system in combination with a reducing agent such as sodium bisulfite, tartaric acid, L-ascorbic acid, formaldehyde sodium sulfoxylate and ferrous sulfate.

The amount of the dispersant used in the aqueous emulsion constituting the adhesive of the present invention is not particularly limited, whether it is an emulsion polymerization type aqueous emulsion or a post-emulsion type aqueous emulsion. 0.1
To 50 parts by weight, preferably 0.5 to 20 parts by weight.
When the amount of the dispersant is less than 0.1 part by weight, the emulsion stability and the polymerization stability are reduced. When the amount is more than 50 parts, the viscosity stability in the compounding of the adhesive may be reduced.

(B) The degree of saponification of the adhesive of the present invention is 5
0 mol% or more and a cationic group in a molecule of 0.1 to 2
The polyvinyl alcohol having 0 mol% is not particularly limited as long as it is a modified polyvinyl alcohol having a cationic group in the molecule, but typically, a cationic group represented by the following general formula (I) is particularly present in the molecule. Modified polyvinyl alcohol in the main chain is exemplified.

[0011]

Embedded image

X: H or CH ₃ Y; CONR ¹ R ² or CH ₂ OCH ₂ AB ｛R ¹ is H, CH ₃ , C ₂ H ₅ , n-C ₃ H ₇ or i-C ₃ H ₇
R ² is H, CH ₃ , C ₂ H ₅ or CR ³ R ⁴ (CH ₂ )
_n N ⁺ (CH ₃ ) ₃ .Z ⁻ , R ³ and R ⁴ each represent H or CH ₃ , n represents an integer of 1 to 9, Z ⁻ represents an anion, and A represents CH (OH) CH _2. , C (CH ₃ ) (OH) C
H ₂ or CH (OH) CH ₂ CH ₂ , B is N (R ⁵ ) ₂
Or _{^{N + (R 5) 3 ·}} Z - a, R ⁵ is CH ₃ or C ₂ H ₅
Represents ｝

Such a modified polyvinyl alcohol is
It is obtained by copolymerizing a vinyl ester monomer and a monomer represented by the following general formula (II), and saponifying the copolymer.

[0014]

Embedded image

As the monomer represented by the formula (II), representatively, trimethyl- (3-acrylamido-3-dimethylpropyl) -ammonium chloride, 3-acrylamidopropyltrimethylammonium chloride, 3-methacrylamide Propyltrimethylammonium chloride, a quaternary ammonium salt of N- (3-allyloxy-2-hydroxypropyl) dimethylamine,
Quaternary ammonium salts of N- (4-allyloxy-3-hydroxybutyl) diethylamine, furthermore, acrylamide, N-methylacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide, diacetoneacrylamide, N-methylolacrylamide, methacrylamide And cationic monomers such as quaternary ammonium salts such as N-methylmethacrylamide, N-ethylmethacrylamide and N-methylolmethacrylamide. In addition, as the above-mentioned vinyl ester monomer, in addition to vinyl acetate, vinyl formate, vinyl propionate, vinyl versatate, vinyl pivalate and the like can also be used.

The (B) cationic group-modified polyvinyl alcohol constituting the adhesive of the present invention may be a copolymer of another ethylenically unsaturated monomer as long as the effects of the present invention are not impaired. Such ethylenically unsaturated monomers include, for example, ethylene, propylene, 1-butene,
Olefins such as isobutene, acrylic acid, methyl acrylate, ethyl acrylate, n-propyl acrylate,
Acrylic esters such as i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate, methacrylic acid, methyl methacrylate , Ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate,
Methacrylic esters such as dodecyl methacrylate and octadecyl methacrylate, methyl vinyl ether, n-
Vinyl ethers such as propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, and stearyl vinyl ether; nitriles such as acrylonitrile and methacrylonitrile; vinyl chloride; vinylidene chloride; Vinyl halides, vinyl halides such as vinylidene fluoride, allyl acetate,
Allyl compounds such as allyl chloride, fumaric acid, maleic acid, itaconic acid, maleic anhydride, phthalic anhydride, carboxyl group-containing compounds such as trimellitic anhydride or itaconic anhydride and esters thereof, ethylenesulfonic acid, allylsulfonic acid, Examples thereof include sulfonic acid group-containing compounds such as methallylsulfonic acid and 2-acrylamido-2-methylpropanesulfonic acid, vinylsilyl compounds such as vinyltrimethoxysilane, and isopropenyl acetate. Further, in the presence of a thiol compound such as thiolacetic acid or mercaptopropionic acid, a terminal ester-modified polyvinyl alcohol obtained by copolymerizing a vinyl ester monomer such as vinyl acetate and a cationic monomer and saponifying it. Can also be used.

The cationic group-modified polyvinyl alcohol (B) constituting the adhesive of the present invention must have a saponification degree of 50 mol% or more and a cationic group modification amount of 0.1 to 20 mol%. The saponification degree is preferably at least 70 mol%, more preferably at least 90 mol%, further preferably at least 94 mol%. If the saponification degree is lower than 50 mol%, the water solubility of the cationic group-modified polyvinyl alcohol decreases, and the productivity of the adhesive decreases and the mixing stability with the aqueous emulsion decreases. The cationic group modification amount is preferably 0.2 to 1
It is 8 mol%, more preferably 0.3 to 15 mol%. When the cationic group modification amount is less than 0.1 mol%, the water solubility of polyvinyl alcohol is reduced, so that the productivity of the adhesive is reduced and the adhesive strength is reduced due to the influence of the undissolved polyvinyl alcohol powder. It is not preferable because it may occur. When the cationic group modification amount exceeds 20 mol%, the water-resistant adhesive property, which is the original performance of the present adhesive, may be reduced. Furthermore, the degree of polymerization of polyvinyl alcohol constituting the adhesive of the present invention is not particularly limited, but is preferably 100 to 100 from the viewpoint of dissolution rate and adhesive strength.
8000, more preferably 200 to 4000 is used. Further, the cationic group-modified polyvinyl alcohol of the present invention is more preferably used as a powder. The particle size of the powder is not particularly limited, but is 500 from the viewpoint of solubility and the like.
μm or less is preferable, and 300 μm or less is more preferable.
The drying conditions for the production of the cationic group-modified polyvinyl alcohol are not particularly limited, but are preferably 80 ° C. or lower, more preferably 50 ° C. or lower, from the viewpoint of the dissolution rate and the like.

The adhesive of the present invention comprises (A) an aqueous emulsion and (B) a polyvinyl alcohol having a saponification degree of 50 mol% or more and a cationic group in a molecule of 0.1 to 20 mol%. (C) a polyisocyanate compound. Here, (C) the polyvalent isocyanate compound has two or more isocyanate groups in the molecule, and for example, tolylene diisocyanate (TDI); hydrogenated TDI; trimethylolpropane-TDI adduct (for example, manufactured by Bayer AG) , Product name: D
esmodur L); triphenylmethane triisocyanate; methylenebisdiphenyl isocyanate (M
DI); hydrogenated MDI; polymerized MDI; hexamethylene diisocyanate; xylylene diisocyanate;
-Dicyclohexylmethane diisocyanate; isophorone diisocyanate. 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. In addition, (C) the polyvalent isocyanate compound may be directly added to the main ingredient, or may be diluted with various solvents that do not substantially react with the isocyanate, for example, dibutyl phthalate or toluene. By blending this (C) polyvalent isocyanate compound, excellent adhesive strength and water resistance are imparted.

In the adhesive of the present invention, the mixing ratio of (A) the aqueous emulsion and (B) polyvinyl alcohol having a saponification degree of 50 mol% or more and containing a cationic group in the molecule of 0.1 to 20 mol% is as follows: (A) /
(B) = 99.5 / 0.5 to 50/50 is usually adopted as a preferable range. Further, the compounding ratio of the (C) polyvalent isocyanate compound is represented by the following formula: (A) +
(B)｝ / (C) = 100 / 0.5 to 100/100, preferably 100/1 to 100/80
Is more preferable. If the polyvalent isocyanate compound is less than this range, the adhesive strength and water resistance will be low,
On the other hand, when the amount exceeds this range, the pot life after blending the polyvalent isocyanate is shortened, which is not practical.

In the adhesive of the present invention, if necessary, starch, modified starch, oxidized starch, sodium alginate, carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, maleic anhydride-
Water-soluble polymer compounds such as isobutene copolymer, maleic anhydride-styrene copolymer, maleic anhydride-methylvinyl ether copolymer, urea-formalin resin, urea
Thermosetting resins generally used as adhesives, such as melamine-formalin resins and phenol-formalin resins, can also be used as appropriate. Further, the adhesive of the present invention may contain fillers such as clay, kaolin, talc, calcium carbonate, and wood flour, fillers such as flour, pigments such as titanium oxide, and various additives such as preservatives and rust preventives. An agent can be appropriately added as needed.

Further, the present invention relates to (A) an aqueous emulsion, wherein (B) polyvinyl alcohol having a saponification degree of 50 mol% or more and containing a cationic group in a molecule of 0.1 to 20 mol% is added at 60 ° C. or less. And (C) a polyvalent isocyanate. That is, the adhesive of the present invention comprises (A) an aqueous emulsion and (B) a saponification degree of 5
0 mol% or more and a cationic group in a molecule of 0.1 to 2
As long as it is composed of polyvinyl alcohol containing 0 mol% as a main component and (C) a polyvalent isocyanate, the production method is not particularly limited. ) Saponification degree 50mol%
0.1 to 20 mol% of the cationic group in the molecule
In the case of a production method characterized by adding a polyvinyl alcohol to be contained at a temperature of 60 ° C. or lower to prepare a main ingredient and blending (C) a polyvalent isocyanate therein, the stability is particularly high during the production of the main ingredient, and Since the main component can be produced at a relatively low temperature, an adhesive composition having low energy cost and high productivity can be obtained. The addition temperature of the cationic group-modified polyvinyl alcohol is preferably 50 ° C. or lower, more preferably 45 ° C. or lower. In addition, when a cationic group-modified polyvinyl alcohol is added to an aqueous emulsion, it is necessary that the polyvinyl alcohol dissolves quickly and does not cause undissolved or aggregation of the emulsion. As 10
Preferably, it dissolves in 60% or more by weight of water at a predetermined temperature, more preferably 70% or more. Furthermore, when the polyvinyl alcohol is added to the aqueous emulsion, the solubilized polyvinyl alcohol particles may coagulate with each other to form a so-called mamako state, which may lower the solubility. For example, polyvinyl alcohol is preliminarily blended with an inorganic substance such as calcium carbonate. Is also preferably used.

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.

[0023]

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.

Example 1 Ethylene-vinyl acetate copolymer emulsion (OM-420)
0, solid content 55%, made by Kuraray) and polyvinyl alcohol (1) (denaturation degree 1700, saponification degree 95 mol%, modified 3-acrylamidopropyltrimethylammonium chloride 2 mol%, particle size 300 μm) per 100 parts by weight of emulsion solid content 5 parts were added and stirred at 40 ° C. for 1 hour to prepare a main ingredient. 15 parts of polymethylene polyphenyl isocyanate (manufactured by Nippon Polyurethane Co., Ltd., trade name: Millionate MR-100) was added to 100 parts by weight of the solid content of the main agent to prepare an adhesive. Using this, a test was performed under the following conditions. The results are shown in Tables 1 and 2.

[Test conditions] State of main agent:-Visual observation: Observed a state in which the main agent was applied thinly on a glass plate. ○: No aggregate, no residual polyvinyl alcohol. △: Little aggregate, low residual polyvinyl alcohol. ×: Aggregate, residual polyvinyl alcohol. Many 2. Adhesion test An adhesion test was performed using the above adhesive 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, repeated boiling) (Test piece only) Measure the compressive shear adhesive strength according to JIS K-6852 Normal strength: Measured as it is after curing for 7 days at 20 ° C. Repeated boiling: After curing for 7 days at 20 ° C., immerse the test piece in boiling water for 4 hours After that, 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 a test in a wet state.

Example 2 A polyvinyl alcohol having a mercapto group at a terminal (polymerization degree: 500, saponification degree: 88.2 mol%, mercapto group content: 4.5 ×) was placed in a glass polymerization vessel equipped with a stirrer, a nitrogen inlet, and a thermometer. 5 parts of (10-5 mol / g-polyvinyl alcohol) and 100 parts of ion-exchanged water were added and dissolved by heating. After cooling, the pH was adjusted to 3.0 with sulfuric acid, and then the temperature was raised to 70 ° C. while performing nitrogen bubbling. 15 stirs
At 0 rpm, 10 parts of methyl methacrylate and 10 parts of n-butyl acrylate were added, and 10 parts of a 1% aqueous potassium persulfate solution was further added to initiate polymerization. One hour after the start of the polymerization, 40 parts of methyl methacrylate, 38 parts of n-butyl acrylate, and 2 parts of hydroxyethyl methacrylate were uniformly dropped over 2 hours. After the completion of dropping, the temperature is raised
C. and left for 1 hour. Methyl methacrylate-n-butyl acrylate-hydroxyethyl methacrylate copolymer emulsion having a solid concentration of 48.5% (acryl E
m) was obtained. To this emulsion was added 5 parts of polyvinyl alcohol (1) per 100 parts by weight of the solid content of the emulsion, and the mixture was stirred at 40 ° C. for 1 hour to prepare a main ingredient. An adhesive was prepared by adding 15 parts of polymethylene polyphenylisocyanate (manufactured by Nippon Polyurethane Co., Ltd., trade name: Millionate MR-100) to 100 parts by weight of the main agent solid content. Using this, the same evaluation as in Example 1 was performed.
The results are shown in Tables 1 and 2.

Example 3 Styrene-butadiene copolymer emulsion (DL-6)
12, a solid content of 50%, manufactured by Asahi Kasei), 5 parts of polyvinyl alcohol (1) was added per 100 parts by weight of the solid content of the emulsion, and the mixture was stirred at 40 ° C. for 1 hour to prepare a main ingredient.
An adhesive was prepared by adding 15 parts of polymethylene polyphenylisocyanate (manufactured by Nippon Polyurethane Co., Ltd., trade name: Millionate MR-100) to 100 parts by weight of the main agent solid content. Using this, the same evaluation as in Example 1 was performed. The results are shown in Tables 1 and 2.

Example 4 In Example 3, polyvinyl alcohol (2) was used in place of polyvinyl alcohol (1) (degree of polymerization: 550, degree of saponification: 62 mol%, modification of 3-methacrylamidopropyltrimethylammonium chloride: 4 mol%, particle size: 400 μm).
m) except that m) was used, and 15 parts of polymethylene polyphenylisocyanate (manufactured by Nippon Polyurethane Co., trade name: Millionate MR-100) was added to 100 parts by weight of the solid content of the base material, and an adhesive was prepared. Was prepared.
Using this, the same evaluation as in Example 1 was performed. The results are shown in Tables 1 and 2.

Example 5 In Example 3, instead of polyvinyl alcohol (1), 2.5 parts of polyvinyl alcohol (1) and polyvinyl alcohol (3) (polymerization degree: 1700, saponification degree: 88 mol per 100 parts by weight of emulsion solids) %, Modified with 3 parts of 3-methacrylamidopropyltrimethylammonium chloride, 1 mol%, particle size 300 μm).
Parts by weight of polymethylene polyphenylisocyanate (manufactured by Nippon Polyurethane Co., trade name: Millionate MR-10)
15) was added to prepare an adhesive. Using this,
The same evaluation as in Example 1 was performed. The results are shown in Tables 1 and 2.

Example 6 A base material was prepared in the same manner as in Example 3 except that polyvinyl alcohol (1) was used in an amount of 10 parts per 100 parts by weight of the solid content of the emulsion. Phenyl isocyanate (manufactured by Nippon Polyurethanes, trade name: Millionate MR-100)
Was added to prepare an adhesive. Using this, the same evaluation as in Example 1 was performed. The results are shown in Tables 1 and 2.

Example 7 A base material was prepared in the same manner as in Example 3 except that the polyvinyl alcohol (1) was used in an amount of 1 part per 100 parts by weight of the solid content of the emulsion. 15 parts of phenyl isocyanate (manufactured by Nippon Polyurethane Co., trade name: Millionate MR-100) was added to prepare an adhesive. Using this, the same evaluation as in Example 1 was performed. The results are shown in Tables 1 and 2.

Example 8 An adhesive was prepared in the same manner as in Example 3 except that 3 parts of polymethylene polyphenyl isocyanate (manufactured by Nippon Polyurethane Co., trade name: Millionate MR-100) was used. Using this, the same evaluation as in Example 1 was performed. The results are shown in Tables 1 and 2.

Example 9 The procedure of Example 3 was repeated, except that polyvinyl alcohol (1) was added with 5% by weight of calcium carbonate in advance. The results are shown in Tables 1 and 2.

Comparative Example 1 In Example 3, polyvinyl alcohol (4) (degree of polymerization: 1700, degree of saponification: 98 mol%, unmodified, particle size: 350 μm)
m) was prepared in the same manner as in Example 3 except that 5 parts per 100 parts by weight of the emulsion solids were used.
00 parts by weight of polymethylene polyphenylisocyanate (manufactured by Nippon Polyurethane Co., trade name: Millionate MR-
100) was added to prepare an adhesive. Using this, the same evaluation as in Example 1 was performed. The results are shown in Tables 1 and 2.

Comparative Example 2 In Example 3, polyvinyl alcohol (5) (polymerization degree: 1700, degree of saponification: 45 mol%, modification of 3-acrylamidopropyltrimethylammonium chloride: 2 mol%, particle size: 350 μm) was added per 100 parts by weight of emulsion solids. A main agent was prepared in the same manner as in Example 3 except that 5 parts were used, and 15 parts of polymethylene polyphenylisocyanate (manufactured by Nippon Polyurethane Co., trade name: Millionate MR-100) was added to 100 parts by weight of the solid content of the main agent, and an adhesive was added. Prepared. Using this, the same evaluation as in Example 1 was performed.
The results are shown in Tables 1 and 2.

Comparative Example 3 The procedure of Example 3 was repeated except that no polyvinyl alcohol was used. Using this, the same evaluation as in Example 1 was performed. The results are shown in Tables 1 and 2.

Comparative Example 4 The procedure of Example 3 was repeated except that polymethylene polyphenylisocyanate (manufactured by Nippon Polyurethane Co., trade name: Millionate MR-100) was not used. Using this, the same evaluation as in Example 1 was performed. The results are shown in Tables 1 and 2.

[0038]

[Table 1]

[0039]

[Table 2]

[0040]

According to the present invention, an adhesive excellent in adhesive strength and water resistance can be provided, and the stability at the time of manufacturing the main agent is high, and the main agent can be manufactured at a relatively low temperature. Therefore, it is possible to provide a method for producing an adhesive with low energy cost and high productivity. Therefore, the adhesive of the present invention can be applied to the case of bonding various adherends, but can be suitably used particularly for wood and plywood adhesives. In addition to wood-to-wood bonding, wood and paper,
It can also be used for bonding with textiles, inorganic plates, various plastics, etc.

Claims (3)

[Claims] 1. An aqueous emulsion (A) and a saponification degree of 50 mol% or more and (B) a cationic group in a molecule having a degree of saponification of at least 50 mol%.
An adhesive mainly comprising polyvinyl alcohol having 1 to 20 mol% and containing (C) a polyvalent isocyanate. 2. An aqueous emulsion comprising (A) an aqueous emulsion and (B) polyvinyl alcohol having a saponification degree of 50 mol% or more and having a cationic group represented by the following general formula (I) in a molecule of 0.1 to 20 mol%. Adhesive containing (C) a polyvalent isocyanate as a main agent. Embedded image X: H or CH ₃ Y; CONR ¹ R ² or CH ₂ OCH ₂ AB ｛R ¹ is H, CH ₃ , C ₂ H ₅ , nC ₃ H ₇ or iC ₃
H ₇ , R ² is H, CH ₃ , C ₂ H ₅ or CR ³ R ⁴ (CH
₂ ) nN ⁺ (CH ₃ ) ₃ .Z ⁻ , R ³ and R ⁴ each represent H or CH ₃ , n represents an integer of 1 to 9, Z ⁻ represents an anion, and A represents CH (OH) CH ₂ , C (CH ₃ ) (OH)
CH ₂ or CH (OH) CH ₂ CH ₂ , B is N (R ⁵ )
₂ or N ⁺ (R ⁵ ) ₃ .Z—, R ⁵ is CH ₃ or C ₂
Representing the H _5. ｝ 3. An aqueous emulsion (A) having a degree of saponification of not less than 50 mol% and a cationic group in the molecule of 0.1 to 0.1%.
A method for producing an adhesive, comprising adding a polyvinyl alcohol having 20 mol% at a temperature of 60 ° C. or lower to prepare a main agent, and blending (C) a polyvalent isocyanate with the main agent.