JPH11256130A - Adhesive, its production method and laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive having excellent adhesive strength, particularly excellent initial adhesive strength, a long pot life, and excellent boiling repetition strength. The main ingredient can be manufactured at a relatively low temperature,
To provide a method for producing an adhesive with low energy cost and high productivity. SOLUTION: The solubility after immersion in (A) an aqueous emulsion and (B) water at 40 ° C. for 1 hour is 50% by weight or more;
An adhesive consisting of polyvinyl alcohol having a surface tension of not less than 45 mN / m and a carboxyl group of 0.2 to 5 mol% and a polyvalent isocyanate compound (C); A method for producing an adhesive in which the base material is prepared by adding the powder of (1), and (C) is added thereto.

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 having an excellent adhesive strength, especially an initial adhesive strength, a long pot life, and a high stability in the production of a base material. 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.

Conventionally, an adhesive comprising a water-soluble polymer, an aqueous emulsion and an isocyanate compound is mainly composed of an aqueous emulsion obtained by adding an aqueous solution obtained by heating and dissolving a water-soluble polymer, polyvinyl alcohol, to an aqueous emulsion. Prior to use, an isocyanate compound was added as a cross-linking agent to the base material 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. Further, the above-mentioned conventional adhesives do not sufficiently satisfy the initial adhesive strength, and further improvement of the initial adhesive strength is desired. Further, improvement of the pot life is desired from the viewpoint of operability.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in the prior art, and provides an adhesive having excellent adhesive strength, especially excellent initial adhesive strength, a long pot life, and excellent boiling repetition strength. In addition, it is an object of the present invention to provide a method for producing an adhesive which has high stability at the time of production of a main agent and can produce the main agent at a relatively low temperature, so that the energy cost is low and the productivity is high. .

[0005]

The object of the present invention is to provide (A) an aqueous emulsion, (B) a solubility of 50% by weight or more after immersion in water at 40 ° C. for 1 hour, and a 1% by weight aqueous solution having a surface tension of 45 mN. / M or more and a carboxyl group of 0.1.
This is achieved by providing an adhesive comprising 2 to 5 mol% of polyvinyl alcohol and (C) a polyvalent isocyanate compound. The above purpose is
(A) The solubility after immersion in an aqueous emulsion and (B) water at 40 ° C. for 1 hour is 50% by weight or more, the surface tension of a 1% by weight aqueous solution is 45 mN / m or more, and the carboxyl group is 0.2% or less. This is achieved by blending a polyvinyl alcohol powder containing 〜5 mol% to prepare a main ingredient, and providing a method for producing an adhesive in which (C) a polyvalent isocyanate compound is blended. The method for producing the above-mentioned adhesive is (A)
It is more preferably carried out by blending (B) with (B) and preparing the main ingredient under the condition of 60 ° C. or lower. The method for producing the adhesive is more preferably performed by using a polyvinyl alcohol powder having a particle size of 500 μm or less as the (B) polyvinyl alcohol powder.

[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.
Among these aqueous emulsions, an aqueous emulsion of a polymer containing a diene such as butadiene as a monomer unit, such as an aqueous emulsion of a styrene-butadiene copolymer; a monomer containing (meth) acrylic acid ester as a monomer unit Aqueous emulsion, for example, methacrylic acid ester-acrylic acid ester copolymer aqueous emulsion; polymer aqueous emulsion containing vinyl ester such as vinyl acetate as a monomer unit, for example, ethylene-vinyl acetate copolymer aqueous emulsion Are preferred.

[0008] In carrying out the emulsion polymerization for obtaining the aqueous emulsion (A) constituting the adhesive of the present invention, in the presence of water, the above-mentioned dispersant, and a polymerization initiator,
A normal emulsion polymerization method in which the above-mentioned monomer is added temporarily or continuously, followed by heating and stirring, can be carried out, or a monomer obtained by previously emulsifying and mixing a monomer with an aqueous dispersant solution is continuously added. May also be implemented. 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 hydroperoxide, benzoyl peroxide, isopropylbenzene peroxide or the like alone or sodium bisulfite, tartaric acid, L-ascorbic acid, formaldehyde sodium sulfoxylate, It is used in a redox system in combination with a reducing agent such as ferrous sulfate.

The amount of the dispersant to be used in the aqueous emulsion (A) 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. 0.2 to 50 parts by weight, preferably 0.5 to 20 parts by weight. When the amount of the dispersant is less than 0.2 parts by weight, the emulsion stability and the polymerization stability are reduced, and when the amount is more than 50 parts, the viscosity stability in the compounding of the adhesive may be reduced.

The (B) polyvinyl alcohol (PVA) used in the adhesive of the present invention has a solubility of 50% by weight or more after immersion in water at 40 ° C. for 1 hour, and 1% by weight of PVA.
It is important that the aqueous solution has a surface tension of 45 mN / m or more and is a PVA containing 0.2 to 5 mol% of a carboxyl group. By using PVA that satisfies this requirement, as is apparent from the examples described below, even when the main agent is prepared at a low temperature, no or little aggregation occurs, and therefore, the main agent is prepared with low energy. be able to. Further, the low-temperature viscosity stability of the base material thus obtained is excellent. Furthermore, an adhesive obtained by blending a polyvalent isocyanate with the main component is particularly excellent in initial adhesive strength, further excellent in repeated boiling adhesive strength, furthermore, there is little increase in viscosity over time and long pot life. A preferred solubility is at least 60% by weight, more preferably at least 70% by weight. Further, a preferable surface tension is 50 mN / m or more, and more preferably 50 to 70 mN / m.

In the case of using a PVA having a solubility of less than 50% by weight or a surface tension of less than 45 mN / m and preparing the main component at a low temperature, aggregation may occur as is apparent from a comparative example described later. , PVA remains undissolved, and normal adhesion. The adhesive strength after repeated boiling may not be sufficient. PVA having such solubility is known as P
The degree of saponification, degree of polymerization, particle size, and carboxyl group content of VA can be obtained by appropriately selecting the degree of saponification, and PVA having the above surface tension can be obtained by appropriately selecting the degree of saponification and degree of polymerization. As described above, PVA having the above-mentioned solubility and surface tension can be obtained by the above-mentioned various factors, and the degree of saponification is 50 mol% or more, preferably 70 mol% or more, and more preferably 80 to 96 mol%. , The degree of polymerization is selected from the range of 100 to 8000, preferably 400 to 4000.

As PVA satisfying such conditions, for example, in the case of PVA having a degree of polymerization of 1700, PVA having a saponification degree of 85 mol% or more and a particle size of 500 or less is used.
A is exemplified as a suitable thing. Here, the solubility refers to a filtration rate (% by weight) calculated by adding a PVA to water at 40 ° C. so as to be 10% by weight, stirring the mixture for 1 hour, and then filtering the residue with a 200 mesh wire mesh. The surface tension refers to a value {mN (millinewton) / m (meter)} obtained by measuring a 1% by weight aqueous PVA solution (20 ° C.) using a “Wilhelmi surface tensiometer”.

(B) PVA constituting the adhesive of the present invention
It is important that the carboxyl group has 0.2 to 5 mol% in the molecule, and the use of PVA having such a carboxyl group can prolong the pot life of the adhesive. The operability of the adhesive becomes excellent. This carboxyl group-modified PVA can be obtained by various methods, and usually, a vinyl ester monomer represented by vinyl acetate is converted to acrylic acid, methacrylic acid, fumaric acid, maleic anhydride, (anhydride) ) Copolymerized with an ethylenically unsaturated carboxylic acid such as itaconic acid and then saponified (random copolymer) or
A product obtained by radically polymerizing the above ethylenically unsaturated carboxylic acid in the presence of a PVA polymer having a thiol group at the terminal (block copolymer), and a product obtained by introducing a carboxyl group into the PVA polymer by a post-reaction ( For example, a Michael adduct such as acrylic acid) is preferably used. Also, as the carboxyl group, part or all of it is sodium,
It may be an alkali metal base such as potassium.
The content of carboxyl groups is preferably 0.3 to 5 mol%
And more preferably 0.5 to 5 mol%. 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) carboxyl group-modified PVA 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, isobutene, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, trimethyl- (3-acrylamide-3-
Dimethylpropyl) -ammonium chloride, acrylamide-2-methylpropanesulfonic acid and its sodium salt, ethyl vinyl ether, butyl vinyl ether, N-vinyl pyrrolidone, vinyl chloride, vinyl bromide,
Vinyl fluoride, vinylidene chloride, vinylidene fluoride, tetrafluoroethylene, sodium vinyl sulfonate,
And sodium allyl sulfonate. Also,
A terminal-modified PVA 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 and saponifying the same can also be used.

The adhesive of the present invention contains (A) the aqueous emulsion and (B) a carboxyl group in a molecule of 0.2 to 0.2%.
The main component is polyvinyl alcohol containing 20 mol%,
It comprises (C) a polyvalent isocyanate compound. Here, (C) the polyvalent isocyanate compound has two or more isocyanate groups in the molecule,
For example, tolylene diisocyanate (TDI); hydrogenated TDI; trimethylolpropane-TDI adduct (eg, Desmodur L, manufactured by Bayer); triphenylmethane triisocyanate; methylenebisdiphenyl isocyanate (MDI); hydrogenated MDI; MDI; hexamethylene diisocyanate; xylylene diisocyanate; 4,4-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 boiling repetition strength are imparted.

In the adhesive of the present invention, (A) an aqueous emulsion and (B) a carboxyl group in a molecule of 0.2 to 0.2%
As the blending ratio of PVA containing 5 mol%, (A) / (B) = 99.5 / 0.5 to 50/50 is usually adopted as a preferable range in terms of solid content weight ratio. The mixing ratio of the polyvalent isocyanate compound (C) is {(A) + (B)} / (C) = 100 / 0.5 to 100 in terms of solids weight ratio.
/ 100/100/1 to 100/1
The range of 00/80 is more preferable. If the polyvalent isocyanate compound is less than this range, the adhesive strength and the boiling repetition strength will be low, and if it exceeds this range, the pot life after blending the polyvalent isocyanate will be short and 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 containing (B) a carboxyl group in a molecule of 0.2 to 5 mol%.
The present invention also provides a method for preparing an adhesive in which a main agent is prepared by adding a PVA powder contained therein, and (C) a polyvalent isocyanate is blended therein. According to the production method of the present invention, particularly, the stability at the time of producing the main agent is high, and furthermore, since the main agent can be produced at a relatively low temperature, an energy cost is low and an adhesive having high productivity can be obtained. The resulting adhesive is excellent in adhesive strength, especially in initial adhesive strength.

In the production method of the present invention, it is preferable to add a carboxyl group-modified PVA powder to the aqueous emulsion (A) at a temperature of 60 ° C. or lower to prepare a main ingredient. More preferably, it is 50 ° C. or less, and most preferably 45 ° C.
It is below ° C. A suitable lower limit of the temperature is 5 ° C or higher, more preferably 10 ° C or higher. Further, when adding the PVA, when there is a possibility that the swollen PVA particles are aggregated with each other to form a so-called mamako state and the solubility is reduced, for example, a preliminarily blended PVA with an inorganic substance such as calcium carbonate is added. Is also preferably used.

Further, as the (B) PVA powder of the present invention,
It is best to use a powder having a particle size of 500 μm or less and mix it with the aqueous emulsion (A) to prepare a main ingredient in order to achieve the object of the present invention. The PVA particle size is 300
μm or less, more preferably 20 μm or less.
0 μm or less, optimally 100 μm or less. The lower limit of the particle size is preferably at least 40 μm, more preferably at least 50 μm. By using the PVA powder having such a particle size, the base material can be prepared at low energy cost, and a high-performance adhesive can be obtained. The method for obtaining such PVA powder is not particularly limited, and for example, those obtained by forcibly pulverizing various kinds of wet or dry pulverizers after saponification or those obtained by physically sieving fine powder naturally generated in the process are usually used. . P at that time
The conditions for drying the VA powder are not particularly limited, but are preferably 80 ° C. or lower, more preferably 50 ° C. or lower, from the viewpoint of the dissolution rate of the PVA powder. Here, the particle size is an average particle size, and is expressed as a particle size (median size) at a point where the integrated value of the weight for each fraction measured by a JIS sieve becomes 50%.

The adhesive of the present invention is used for bonding various adherends, and various laminates can be obtained. Examples of the adherend include wood, plywood, paper, fiber, various plastics, and the like, and examples of the laminate include a wood laminate and a plywood laminate. 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.

[0022]

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 PVA powder (1) (polymerization degree 1700, saponification degree 95 mol%, maleic anhydride 2 mol%)
Denaturation, particle size 300 μm, solubility 90% by weight, surface tension 6
0 mN / m) was added in an amount of 5 parts 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.
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 to 3.

[Test conditions] Low-temperature viscosity stability of main agent: After the main agent was left at 5 ° C. for 7 days, the appearance was observed. ：: no change in appearance ×: gelation 2. State of main agent:-Visual observation: Observed a state in which the main agent was applied thinly on a glass plate. ○: No aggregates ×: Many aggregates Adhesion test An adhesion test was performed using the above adhesive under the following conditions. Substrate: birch / birch (masa) water content 8% Application amount: 250 g / m ² (both sides applied) Deposition time: 1 minute Pressing conditions: 20 ° C., 24 hours, pressure 10 kg / cm
² (Normal strength, repeated boiling test specimens only) Measure compression shear adhesive strength according to JIS K-6852 Normal strength: Measured as it is after curing for 7 days at 20 ° C Repeated boiling: Test specimen after curing for 7 days at 20 ° C Was immersed in boiling water for 4 hours, 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. . Initial adhesive strength: 10 kg / cm ² at 20 ° C. after bonding
, And immediately measured. 4. Viscosity change rate: 40 ° C. Viscosity increase rate after standing for 2 hours The smaller the viscosity increase rate, the longer the pot life and the better the operability of the adhesive.

Example 2 In a glass polymerization vessel equipped with a stirrer, a nitrogen inlet, and a thermometer, PVA having a mercapto group at a terminal (degree of polymerization: 5
00, saponification degree 88.2 mol%, mercapto group content 4.
5 × 10 ⁻⁵ mol / g-PVA) and 5 parts of ion-exchanged water
0 parts 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. With stirring at 150 rpm, 10 parts of methyl methacrylate and 10 parts of n-butyl acrylate were added, and 10 parts of a 1% aqueous solution of potassium persulfate was further added to initiate polymerization. One hour after the start of the polymerization, methyl methacrylate 40
Parts, 38 parts of n-butyl acrylate and 2 parts of hydroxyethyl methacrylate were uniformly dropped over 2 hours. After completion of the dropwise addition, the temperature was raised to 80 ° C., and the mixture was left for 1 hour. Methyl methacrylate-n-acrylic acid having a solid content of 48.5%
A butyl-hydroxyethyl methacrylate copolymer emulsion (acrylic Em) was obtained. PVA powder (1) was added to this emulsion with an emulsion solid content of 100.
5 parts per part by weight was added and 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 to 3.

Example 3 Styrene-butadiene copolymer emulsion (DL-6)
12, solid content concentration 50%, manufactured by Asahi Kasei), PVA (1)
5 parts per 100 parts by weight of emulsion solids
The main agent was prepared by stirring at 0 ° C. for 1 hour. Main agent solid content 10
0 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 to 3.

Example 4 In Example 3, PVA powder (1) was used instead of PVA powder (1).
A main agent was prepared in the same manner as in Example 3 except that powder (2) (polymerization degree: 550, degree of saponification: 62 mol%, modification of itaconic acid: 3 mol%, particle size: 350 μm, solubility: 95% by weight, surface tension: 51 mN / m) was used. Then, 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, the same evaluation as in Example 1 was performed. The results are shown in Tables 1 to 3.

Example 5 In Example 3, PVA powder (1) was used instead of PVA powder (1) per 100 parts by weight of emulsion solids.
5 parts and PVA powder (3) (degree of polymerization 1800, degree of saponification 88
Mol%, itaconic acid 1 mol% modified, particle size 300 μm, solubility 95% by weight, surface tension 55 mN / m) A main agent was prepared in the same manner as in Example 3 except that 2.5 parts by mass was used. Polymethylene polyphenyl 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. Table 1 shows the results.
3 is shown.

Example 6 A base material was prepared in the same manner as in Example 3 except that the PVA powder (1) was used in an amount of 10 parts 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 to 3.

Example 7 A base material was prepared in the same manner as in Example 3 except that the PVA powder (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 to 3.

Example 8 An adhesive was prepared in the same manner as in Example 3 except that 3 parts of polymethylene polyphenylisocyanate (manufactured by Nippon Polyurethane Co., Ltd., 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 to 3.

Example 9 The procedure of Example 3 was repeated, except that the addition of 5% by weight of calcium carbonate in advance to the PVA powder (1) was added. The results are shown in Tables 1 to 3.

Comparative Example 1 In Example 3, PVA powder (4) (polymerization degree 170
0, saponification degree 70 mol%, unmodified, particle size 600 μm, solubility 99% by weight, surface tension 42 mN / m) except that 5 parts per 100 parts by weight of the emulsion solids were used to prepare the main ingredient in the same manner as in Example 3, To 100 parts by weight of the solid content, 15 parts of polymethylene polyphenyl isocyanate (manufactured by Nippon Polyurethane Co., Ltd., 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 to 3.

Comparative Example 2 In Example 3, PVA powder (5) (polymerization degree 170
0, a saponification degree of 95 mol%, unmodified, particle size of 600 μm, solubility of 45 wt%, surface tension of 55 mN / m) were prepared in the same manner as in Example 3, except that 5 parts were used per 100 parts by weight of the emulsion solids. To 100 parts by weight of the solid content, 15 parts of polymethylene polyphenyl isocyanate (manufactured by Nippon Polyurethane Co., Ltd., 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 to 3.

Comparative Example 3 In Example 3, instead of adding 5 parts by weight of the PVA powder (1) per 100 parts by weight of the emulsion solids,
The VA powder (1) was placed in water at 95 ° C., and stirred for 1 hour.
An adhesive was prepared in the same manner as in Example 3 by adding the PVA solid content to 5 parts by weight per 00 parts by weight.
Using this, the same evaluation as in Example 1 was performed. The results are shown in Tables 1 to 3.

Comparative Example 4 In Example 3, instead of adding 5 parts by weight of PVA powder (1) per 100 parts by weight of the solid content of the emulsion,
VA powder (6) (degree of polymerization 1700, degree of saponification 98 mol%, particle size 600 μm, solubility 21% by weight, surface tension 60
mN / m) in 95 ° C. water and stirred for 1 hour to obtain P
A VA aqueous solution (concentration 10%) was added to an emulsion solid content 100
The adhesive was added so that the PVA solid content was 5 parts by weight per part by weight, and an adhesive was prepared in the same manner as in Example 3. Using this, the same evaluation as in Example 1 was performed. Table 1 shows the results
3 are shown.

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

[Table 3]

[0040]

According to the present invention, it is possible to provide an adhesive having an excellent adhesive strength, especially an initial adhesive strength, a long pot life, and an excellent boiling adhesive strength. In addition, since the main agent can be produced at a relatively low temperature, 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 the bonding between woods, it can be used for bonding wood to paper, textiles, inorganic plates, various plastics, and the like.

Claims (7)

[Claims] (A) an aqueous emulsion; (B) a solubility of 50% by weight or more after immersion in water at 40 ° C. for 1 hour, a surface tension of a 1% by weight aqueous solution of 45 mN / m or more, and An adhesive comprising polyvinyl alcohol containing 0.2 to 5 mol% of a group and (C) a polyvalent isocyanate compound. 2. The aqueous emulsion of (A) and (B) the solubility after immersion in water at 40 ° C. for 1 hour is 50% by weight or more, the surface tension of a 1% by weight aqueous solution is 45 mN / m or more, and A main ingredient is prepared by blending polyvinyl alcohol powder containing 0.2 to 5 mol% of a group, and (C)
A method for producing an adhesive, comprising blending a polyvalent isocyanate compound. 3. The method for producing an adhesive according to claim 2, wherein (A) and (B) are blended to prepare a main agent under a condition of 60 ° C. or lower. 4. The method for producing an adhesive according to claim 2, wherein (B) the polyvinyl alcohol powder is a polyvinyl alcohol powder having a particle size of 500 μm or less. 5. A laminate obtained by using the adhesive according to any one of claims 1 to 4. 6. A wood laminate obtained by using the adhesive according to any one of claims 1 to 4. 7. A plywood laminate obtained by using the adhesive according to any one of claims 1 to 4.