JP2005220294A - Adhesive composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive composition that shows excellent adhesion property to lumber not only of broadleaf tree but also of needleleaf tree causing adhesion trouble, has reduced smell and minimized environmental contamination, does not diffuse formaldehyde because the composition is an aqueous emulsion but includes no organic solvent, and has excellent workability, long-term adhesive properties, adhesion properties, resistance to water and resistance to boiling water. <P>SOLUTION: This adhesive composition is produced by adding (D) a compound bearing an isocyanate group to a resin composition comprising (A) an acetoacetyl group-bearing synthetic resin emulsion prepared by emulsion polymerization of a radical-polymerizable unsaturated monomer and an acetoacetyl group-bearing radical-polymerizable monomer in the presence of polysaccharide as a protective colloid, (B) a polyvinyl ester emulsion and (C) a vinyl ester emulsion. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an adhesive composition, and more particularly to an adhesive composition having excellent adhesiveness to softwood by introducing an acetoacetyl group into a specific synthetic emulsion and not containing formaldehyde.

  Conventionally, formaldehyde resin adhesives such as urea-formaldehyde resin adhesive, melamine-formaldehyde resin adhesive, phenol-formaldehyde resin adhesive, resorcinol-formaldehyde resin adhesive are known as water-resistant adhesive compositions for wood. ing. However, since the formaldehyde resin-based adhesive remains free formaldehyde, formaldehyde is released from the building material product or the like bonded with the formaldehyde resin-based adhesive, resulting in health problems, so-called sick house syndrome. The problem has been close up.

  Of the formaldehyde resin adhesives, three types of adhesives, urea-formaldehyde resin adhesive, melamine-formaldehyde resin adhesive, and phenol-formaldehyde resin adhesive, need to be heat-pressed during bonding. It is not suitable for the adhesion of thick materials, especially for laminated wood. On the other hand, the resorcinol-formaldehyde resin adhesive does not require the heat pressing, but requires a long-time cold pressing for 16 hours at an atmospheric temperature of 20 ° C., and therefore has a low work efficiency. Further, the resorcinol-formaldehyde resin adhesive has a problem that its use is limited because the adhesive itself is reddish brown and the adhesive layer is colored in the same color to reduce the commercial value of the product.

  In order to solve the problems of the formaldehyde resin-based adhesive, an aqueous polymer-isocyanate-based adhesive composition comprising a water-soluble polymer aqueous solution, an aqueous latex, an aqueous emulsion, etc. as a main agent, and an isocyanate compound as a curing agent in the main agent. Things are known. Since the aqueous polymer-isocyanate adhesive composition does not contain a formaldehyde resin, there is no risk of environmental pollution due to the release of free formaldehyde, cold pressing is possible, and the adhesive layer is not colored.

  Examples of the aqueous polymer-isocyanate-based adhesive composition include (A) an aqueous solution of polyvinyl alcohol and the presence of an ethylene-vinyl acetate copolymer resin emulsion having an ethylene content of 10 to 45% by weight. 100 to 600 parts by weight of a total of 100 to 600 parts by weight of vinyl acetate and 0 to 40 parts by weight of other vinyl polymerizable monomers per 100 parts by weight of solid content in the system resin emulsion Emulsions, (B) aqueous solutions containing water-soluble polymers such as polyvinyl alcohol, (C) fillers that react with isocyanate compounds, (D) aqueous adhesives composed of polyvalent isocyanate compounds (Patent Document 1), Rubber latex and / or synthetic resin emulsion to 1 part by weight of polymer compound having acetyl group A two-part adhesive comprising a liquid A or an aqueous emulsion obtained by mixing within a range of up to 10 parts by weight as a solid content, and a liquid B containing an hydrazine compound such as adipic acid dihydrazide or a dispersion. (Patent Document 2), a water-soluble polymer aqueous solution, an aqueous latex, an adhesive containing a main agent composed of one or more of an aqueous emulsion, and a curing agent composed of an isocyanate compound such as 2,4'-diphenylmethane diisocyanate A highly water-resistant adhesive composition characterized by containing polymethylene polyphenyl polyisocyanate in the range of 0 to 40% by weight with respect to the total amount of the curing agent (Patent Document 3) and many others Proposals have been made.

  In general, when an isocyanate compound is directly blended into a solution containing water such as an aqueous solution or an aqueous emulsion, it reacts violently with water and foams significantly. By dissolving the isocyanate compound in a hydrophobic organic solvent, the reaction between the isocyanate compound and water can be suppressed, coating workability can be improved, and the usable time can be extended. Due to the use of solvents, odor generation and environmental pollution problems associated with volatilization of organic solvents are inevitable.

  As an adhesive composition that has high adhesive strength, excellent durability, water resistance and hot water resistance even when it is aqueous, and has a long pot life, (A) a polysaccharide as a protective colloid, a radically polymerizable unsaturated monomer An adhesive composition comprising a synthetic resin emulsion obtained by emulsion polymerization of a monomer, (B) polyvinyl alcohol, and (C) a compound having an isocyanate group has been proposed (see Patent Document 4).

Among these adhesive compositions described in each of the above publications, it is effective for bonding plywood made of wood having a small specific gravity, but in bonding of laminated wood made of wood having a high specific gravity, such as birch material. , Cases where water resistance that can sufficiently satisfy the Japanese Agricultural Standards for wood laminates cannot be obtained, and water resistance, heat resistance and durability cannot be satisfied in response to the recent demand for advanced adhesives Things can also be seen.
However, in recent years, hardwood resources have become scarce and it has become difficult to obtain, and the proportion of plywood made from conifers is increasing year by year. Since softwood has a particularly large amount of spider components, vinyl acetate resin-based and water-based polymer-isocyanate-based adhesives are extremely inadequate in terms of adhesion to softwood, water resistance, hot water adhesion, durability, stability, etc. Therefore, it did not pass JAS special standards that required severe boiling water resistance for plywood.

JP 2001-107006 A JP 2001-179714 A JP 2002-194317 A JP 2003-313530 A

  The object of the present invention is to provide an adhesive composition having excellent adhesion to hard-to-adhere plywood such as conifers, excellent workability without releasing formaldehyde, and especially having a very long pot life. There is to do.

The present invention
[1] (A) A synthetic resin having an acetoacetyl group obtained by emulsion polymerization of a radically polymerizable unsaturated monomer and a radically polymerizable unsaturated monomer having an acetoacetyl group using a polysaccharide as a protective colloid A resin composition comprising an emulsion (hereinafter simply referred to as “synthetic resin emulsion having an acetoacetyl group”), (B) polyvinyl alcohol and (C) vinyl ester emulsion, and (D) a compound having an isocyanate group is blended. An adhesive composition,

[2] (A) The radical polymerizable unsaturated monomer having an acetoacetyl group used in the synthetic resin emulsion is in the range of 1 to 15 parts by weight with respect to 100 parts by weight of the total radical polymerizable unsaturated monomer. The adhesive composition according to the above [1],
[3] (A) The adhesive composition according to [1], wherein the gel fraction of the synthetic resin emulsion is 20% or more,
[4] (A) Synthesis having radical polymerizable unsaturated monomer and radical polymerizable unsaturated monomer having acetoacetyl group obtained by emulsion polymerization using polysaccharide as protective colloid The adhesive composition according to the above [1], which is used in a proportion of 2 to 300 parts by weight of solid content of (B) polyvinyl alcohol with respect to 100 parts by weight of solid content of the resin emulsion,
[5] The adhesive composition according to the above [1], wherein (A) vinyl ester emulsion is blended in a proportion of 10 to 30 parts by weight as a solid content with respect to 100 parts by weight of a solid content of the synthetic resin emulsion. Stuff,
[6] The adhesive composition according to the above [1], wherein (D) the compound having an isocyanate group is blended at a ratio of 2 to 200 parts by weight with respect to 100 parts by weight of the solid content of the (A) synthetic resin emulsion. ,

[7] Using a polysaccharide as a protective colloid, polyvinyl alcohol and vinyl ester are added to a synthetic resin emulsion obtained by emulsion polymerization of a radical polymerizable unsaturated monomer and a radical polymerizable unsaturated monomer having an acetoacetyl group. A method for producing an adhesive composition comprising adding a compound having a group and mixing to obtain a resin composition, and blending the compound having an isocyanate group with the emulsion, and [8] using a polysaccharide as a protective colloid Then, a radically polymerizable unsaturated monomer and a radically polymerizable unsaturated monomer having an acetoacetyl group are mixed with a synthetic resin emulsion obtained by emulsion polymerization by adding an emulsion of polyvinyl alcohol and a compound having a vinyl ester group. To obtain a resin composition, which is blended with a compound having an isocyanate group. Woody plywood or wood-based laminated timber of coniferous using an adhesive composition, have solved the above problems by developing.

  According to the present invention, adhesiveness, adhesiveness, water resistance, boiling resistance can be obtained not only for hardwoods but also problematic softwood base materials, and it has excellent workability without releasing formaldehyde. An adhesive composition having a feature of long time could be provided.

  As a result of intensive studies aimed at solving the above-mentioned problems, the present inventors have found that a synthetic resin emulsion, a polyvinyl alcohol, and a vinyl ester emulsion obtained by copolymerizing a radical polymerizable unsaturated monomer having an acetoacetyl group The present invention was completed by finding out that the above-mentioned problems could be solved only when an isocyanate group-containing compound was blended into a resin composition mixed with an isocyanate composition prior to use to obtain an adhesive composition.

Hereinafter, the present invention will be described in more detail.
(A) Synthetic resin emulsion having an acetoacetyl group (A) The synthetic resin emulsion having an acetoacetyl group used in the adhesive composition of the present invention uses a polysaccharide as a protective colloid and has radical polymerization properties having an acetoacetyl group. It can be obtained by emulsion polymerization of unsaturated monomers and other radical polymerizable unsaturated monomers copolymerizable therewith.
Examples of the polysaccharide used in preparing the synthetic resin emulsion include gum arabic, gutty gum, tragacanth gum, damson gum, cherry gum, peach gum gum, guar gum and the like. These polysaccharides can serve as protective colloids. When a polysaccharide is used as a protective colloid, the usable time of the adhesive composition combined with (B) polyvinyl alcohol and (C) a compound having an isocyanate group is changed to an anionic cation used in ordinary emulsion polymerization. Compared to adhesive compositions using water-soluble polymers other than polysaccharides such as hydrophilic, amphoteric, and nonionic surfactants, various polyvinyl alcohols, and hydroxyethyl cellulose, the length can be dramatically increased. (See Patent Document 4).

  (A) When the radical polymerizable unsaturated monomer and the radical polymerizable unsaturated monomer having an acetoacetyl group are emulsion-polymerized to obtain a synthetic resin emulsion, the amount of polysaccharide used as a protective colloid is It is 0.1-20 weight part with respect to 100 weight part of radically polymerizable unsaturated monomers, Preferably it is 0.5-15 weight part. When the blending amount of the polysaccharide is less than 0.1 parts by weight, the obtained (A) synthetic resin emulsion is poorly stable and aggregates and gels, and when it exceeds 20 parts by weight, it is finally obtained. This is not preferable because the water resistance of the adhesive is significantly reduced. In addition, various polyvinyl alcohols, hydroxyethyl cellulose, and the like can be used in combination with polysaccharides as protective colloids within the range that does not hinder the pot life and adhesion performance.

  A synthetic resin emulsion obtained by emulsion polymerization of a radically polymerizable unsaturated monomer and a radically polymerizable unsaturated monomer having an acetoacetyl group is a monomer containing an acetoacetyl group, such as allyl acetoacetate, vinyl Acetoacetate; (meth) acrylic acid acetoacetate of alkylene glycol such as 2-acetoacetoxyethyl acrylate, 2-acetoacetoxyethyl methacrylate, 2-acetoacetoxypropyl acrylate, 2-acetoacetoxypropyl methacrylate, 2-cyanoacetoacetoxyethyl methacrylate Esters; Crotonic acetoacetate esters of alkylene glycols such as 2-acetoacetoxyethyl crotonate and 2-acetoacetoxypropyl crotonate; N- (acetoacetoxymethyl) acrylic acid Acetoacetate of N-alkylol (meth) acrylamide such as N- (acetoacetoxymethyl) methacrylamide, N- (acetoacetoxyethyl) acrylamide, N- (acetoacetoxyethyl) methacrylamide; 2-hydroxyethyl acrylate 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, 2-hydroxy-3-chloropropyl methacrylate, 1,4-butylene glycol monoacrylate, 1,4-butylene glycol monomethacrylate, N-methylol acrylamide, N-methylol methacrylamide, Examples include acetoacetylated products such as ethylenically unsaturated monomers having a hydroxyl group such as hydroxystyrene, and these may be used alone or in combination of two or more.

  Further, the other radical polymerizable unsaturated monomer copolymerizable with the radical polymerizable unsaturated monomer having an acetoacetyl group is not particularly limited, but methyl (meth) acrylate, ( (Meth) ethyl acrylate, (meth) acrylic acid n-propyl, (meth) acrylic acid isopropyl, (meth) acrylic acid n-butyl, (meth) acrylic acid isobutyl, (meth) acrylic acid sec-butyl, (meth) T-butyl acrylate, n-pentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, (meth) Cyclohexyl acrylate, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, (meth) acrylic 2-methoxypropyl, (meth) acrylic acid 3-methoxypropyl, (meth) acrylic acid 2-methoxybutyl, (meth) acrylic acid 3-methoxybutyl, (meth) acrylic acid 4-methoxybutyl, (meth) acrylic acid (Meth) acrylic esters such as hydroxyethyl, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, and monomers copolymerizable therewith, such as acrylic acid, methacrylic acid, crotonic acid, itacone Examples include α, β-ethylenically unsaturated carboxylic acids such as acids, aromatic vinyl compounds such as styrene and vinyl styrene, and the like. The content of the monomer containing an acetoacetyl group in the copolymer is 1 to 15 parts by weight, preferably 2 to 10 parts by weight, based on 100 parts by weight of all radical polymerizable unsaturated monomers. .

Further, the gel fraction of the synthetic resin emulsion (A) having an acetoacetyl group in the present invention is prepared to be 20% or more. When the gel fraction is less than 20%, the adhesive strength of the finally obtained adhesive is small, and the water resistance is remarkably lowered, which is not preferable.
Here, the gel fraction of the synthetic resin emulsion was measured as follows.

The synthetic resin emulsion is cast on a glass plate and dried at 20 ° C. and a humidity of 65% for 6 days to form a film having a thickness of about 0.3 mm. The dry film was precisely weighed (the weight at this time is W1). This is then wrapped in a wire mesh, immersed in tetrahydrofuran at 20 ° C. (ratio of 50 ml of THF to 0.5 g of the film) for 24 hours, pulled up, air-dried, and the weight of the film is precisely weighed (the weight at this time is W ₂ And).
The gel fraction was calculated by the following formula.
(W ₂ / W ₁ ) × 100 = Gel fraction (%)

  In the adhesive of the present invention, (A) a synthetic resin emulsion having an acetoacetyl group can be produced according to a usual emulsion polymerization method. In the polymerization, a generally used polymerization initiator is used. Specific examples include water-soluble inorganic peroxides or persulfates such as hydrogen peroxide, potassium persulfate, and ammonium persulfate, organic peroxides such as cumene hydroperoxide and benzoyl peroxide, and azo such as azobisisobutylnitrile. Compounds. Further, the polymerization initiator is usually used in combination with a reducing agent such as tartaric acid, formic acid, oxalic acid, acidic sodium sulfite, or longalite. As for the usage-amount of a polymerization initiator, 0.1-2.0 weight part is preferable with respect to 100 weight part of all radically polymerizable unsaturated monomers. Further, the radically polymerizable unsaturated monomer can be subjected to the reaction by batch or divided or continuously dropped. The polymerization temperature can be carried out at a normal temperature of 60 to 90 ° C.

  In addition, chain transfer agents such as lauryl mercaptan, octyl mercaptan, 2-mercaptoethyl alcohol, 2-mercaptopropionic acid, and octyl thioglycolate can be used as molecular weight regulators generally used in emulsion polymerization. Moreover, the film-forming aid and other additives frequently used in the synthetic resin emulsion can be added as necessary.

(B) Polyvinyl alcohol (B) Polyvinyl alcohol used in the adhesive composition of the present invention can be either a normal fully saponified product or a partially saponified product, and a mercapto group-modified product or an acetoacetyl group-modified product. Modified polyvinyl alcohol such as products can be used as well.

Adhesive composition In the adhesive composition of the present invention, a mixture of (A) a synthetic resin emulsion and (B) polyvinyl alcohol is used as a main agent, and the blending is based on 100 parts by weight of the solid content of the (A) synthetic resin emulsion. (B) The solid content of the polyvinyl alcohol is preferably 2 to 300 parts by weight, more preferably 5 to 200 parts by weight. When (B) the polyvinyl alcohol is less than 2 parts by weight, the viscosity increase of the finally obtained adhesive composition after addition of the compound (D) having an isocyanate group, which will be described below, is not preferable. Moreover, when (B) polyvinyl alcohol exceeds 300 weight part, since the water resistance of the adhesive composition finally obtained falls, it is unpreferable.

(C) Vinyl ester emulsion The vinyl ester used in the present invention can be obtained by the reaction of an epoxy resin and an α, β-unsaturated monobasic acid. Epoxy resins are broadly classified into so-called “epi-bis type” having a bisphenol structure and “novolac epoxy type” having a novolac structure. In addition, the demon has a “glycidyl ether type” having a cyclic aliphatic structure, poly Examples thereof include “glycidyl ether type” of ether polyol and “glycidyl ether type” of polyhydric alcohol, and any of them can be used in the present invention. However, from the viewpoint of cost and physical properties, an “epi-bis type” epoxy resin is advantageous.

Examples of α, β-unsaturated monobasic acids to be reacted with epoxy resins to form vinyl esters include acrylic acid, methacrylic acid (hereinafter collectively referred to as “(meth) acrylic acid”), crotonic acid, and maleic acid. Examples thereof include acid monoesters, fumaric acid monoesters, itaconic acid monoesters, and the like, which are selected according to the required slowness of curability of the resin. In general, (meth) acrylic acid is used.
The reaction between the epoxy resin and the α, β-unsaturated monobasic acid is usually carried out under a flow of air (oxygen) by a catalyst such as a tertiary amine, a quaternary ammonium, a quaternary ammonium salt, or triphenylphosphine. It is carried out by heating to 100 to 140 ° C. in the presence. If necessary, the reaction can be carried out in the presence of a reactive diluent such as a polyhydric alcohol to (meth) acrylate. The type and amount of the reactive diluent that can be used in the present invention need not be particularly limited. However, when used for wood bonding or the like that requires hot water resistance, a vinyl ester and a reactive diluent such as polyvalent The compounding amount of the vinyl ester is required to be at least 10% by weight with respect to the total amount of alcohol to (meth) acrylate, and preferably 50% by weight or more.

  This polyhydric alcohol to (meth) acrylate can be obtained by esterifying polyhydric alcohol with (meth) acrylic acid. Examples of the polyhydric alcohol include ethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol, bisphenol A ethylene oxide adduct, bisphenol A propylene oxide adduct, polyethylene glycol, polypropylene glycol, trimethylolpropane, glycerin, pentaerythritol, etc. Is mentioned.

The compounding amount of the vinyl ester emulsion is a ratio of 10 to 30 parts by weight, preferably 15 to 25 parts by weight, based on 100 parts by weight of the solid content of the (A) synthetic resin emulsion. When the blending amount of the vinyl ester emulsion is 10 parts by weight or less, the crosslinking density is lowered, and the boiling resistance in the softwood base material is lowered, which is not preferable.
Moreover, when the compounding quantity of a vinyl ester emulsion is 30 weight part or more, since the pot life after resin compounding becomes short, it is unpreferable.

(D) Compound having isocyanate group The compound containing (D) isocyanate group used in the adhesive composition of the present invention is particularly limited as long as it has two or more isocyanate groups in one molecule. Examples include aliphatic isocyanates such as hexamethylene diisocyanate, m- and p-phenylene diisocyanate, tolylene-2,4- and -2,6-diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylene- Aromatic isocyanates such as 4,4′-diisocyanate, 4,4′-diisocyanate-3,3′-dimethyldiphenyl, 3-methyl-diphenylmethane-4,4′-diisocyanate, diphenyl ether diisocyanate, and cyclohexane-2,4 -And -2,3-diisocyanate Sulfonates, such as alicyclic isocyanates such as isophorone diisocyanate. These can be used alone or in admixture of two or more. Also, isocyanate-terminated prepolymers formed by reaction of excess diisocyanate or polyfunctional polyisocyanate with hydroxyl-terminated polyester or hydroxyl-terminated polyether, and excess diisocyanate or polyfunctional polyisocyanate with ethylene glycol, trimethylolpropane or 1,3 Products obtained by reaction with monomeric polyols such as butanediol or mixtures thereof can also be used.

  (D) The compounding quantity of the compound containing an isocyanate group may be arbitrarily determined depending on the purpose of use, but preferably (A) a composition of synthetic resin emulsion and (B) polyvinyl alcohol (from the resin composition (C It is preferable to add 2 to 100 parts by weight, preferably 5 to 70 parts by weight with respect to 100 parts by weight of the solid content of the component (excluding the component)). (D) If the compounding quantity of the compound containing an isocyanate group is less than 2 parts by weight, a sufficient adhesive force cannot be obtained, which is not preferable. Moreover, when the compounding quantity of the compound containing (D) isocyanate group exceeds 100 weight part, since the pot life after mixing | blending becomes short and a viscosity raise becomes large, it is unpreferable.

Furthermore, the adhesive of the present invention includes, as necessary, fillers such as calcium carbonate, clay, kaolin, talc, and wood flour, fillers such as wheat flour, pigments such as titanium oxide, and others, antiseptics, rust inhibitors Various additives such as can be appropriately added.
Moreover, there is no restriction | limiting in particular about the application | coating method in the case of using the adhesive agent of this invention, or an adhesion | attachment method, It can carry out by what kind of method, if it has been performed conventionally. For example, it can be used in a pressing method in which an adhesive composition is applied to an adhesive surface of wood or the like by brush coating, and the adhesive surface is bonded and fixed by applying pressure. In addition, the adhesive composition of the present invention can be dried by any of the heat pressing method and the room temperature pressing method to obtain sufficient adhesive strength.

  The adhesive composition of the present invention can provide excellent durability, water resistance and hot water adhesion, little increase in viscosity after addition of a compound having an isocyanate group, almost no foaming, and Workability has been improved by significantly extending the pot life. That is, since the adhesive composition of the present invention has extremely great advantages and features as described above, a wide range of uses can be expected. In particular, it has a long pot life, can be cured at room temperature as well as heat-cured, has excellent strength and workability, does not contain formaldehyde, and has the greatest features that can be used for bonding softwood and other softwood. For this reason, it is particularly useful as an adhesive for a wide range of applications such as softwood plywood, decorative plywood, fiberboard, fiber products, and paper products.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited only to these illustration examples at all. In the examples and comparative examples, “parts” and “%” are based on weight unless otherwise specified.

(A) Synthesis of synthetic resin emulsion (Production Example 1)
A 1-liter separable flask equipped with a stirrer, thermometer, reflux condenser, and dropping funnel was charged with 300 parts of a 20% aqueous solution of gum arabic and 210 parts of ion-exchanged water. The temperature was raised to 80 ° C. Thereafter, a monomer mixture of 225 parts of methyl methacrylate, 225 parts of butyl acrylate, 22.5 parts of 2hydroxyethyl acrylate, and 14.5 parts of acetoacetoxyethyl methacrylate was added dropwise over 4 hours. Further, ion exchange water was added to 2 parts of ammonium persulfate, and an aqueous solution with a total amount of 50 g was added dropwise at the same time as the monomer mixture to perform emulsion polymerization.

At this time, the external temperature was controlled so that the internal temperature of the flask was 80 to 85 ° C. After completion of dropping, the mixture was held at 80 to 85 ° C. for 1 hour, and then cooled to 30 ° C. or lower to obtain an emulsion. The resulting aqueous emulsion had a non-volatile content (dried at 105 ° C. for 1 hour) of 48.5%, a viscosity (BH viscometer, No. rotor, 10 rpm, 23 ° C.) of 7,000 mPa · s, and a gel fraction of 35. %Met. This blending ratio is shown in Table 1.
(Production Example 2-4)
In the same manner as in Production Example 1, emulsions were produced with the blending ratios shown in Table 1.

(Example 1)
50 parts of a 15% aqueous solution of polyvinyl alcohol PVA117 (manufactured by Kuraray, completely saponified), 50 parts by weight of calcium carbonate, 240 parts by weight of calcium carbonate, 60% vinyl ester with respect to 100 parts of the solid content of the synthetic resin emulsion obtained in Production Example 1 The emulsion was mixed with 15 parts by weight of solid as a main component. 30 parts of an isocyanate-containing compound, Millionate MR-100 (manufactured by Nippon Polyurethane, polymethylene polyphenyl isocyanate) is added to the solid content of the synthetic resin emulsion in 100 parts of the main agent, and the mixture is mixed thoroughly to give the adhesive of Example 1 Performance evaluation was performed as a composition. The blending ratio is shown in Table 2.

(Example 2, Comparative Example 1-5)
In the same manner as in Example 1, various adhesive compositions were produced at the ratios shown in Table 2.
(Adhesion test with plywood)

  Softwood veneers were bonded using the adhesive compositions obtained in Examples 1 and 2 and Comparative Examples 1 to 5, and the tensile shear strength of the plywood was measured. The measurement method and measurement conditions are described below. The measurement results are shown in Table 3.

(1) Adhesion conditions Base material: Karamatsu single plate (thickness 0.55 / 1.2 / 0.55mm, cross-bonded 3ply), moisture content 8%
Application amount: 220 g / m ² (single-sided application)
Clamping: Cold pressure 10 kg / cm ² -30 minutes → Hot pressure 120 ° C x 10 kg / cm ² -2 minutes

(2) Test method Tensile shear test by JAS (3) Measurement method Normal state adhesive strength; measured under standard conditions at 20 ° C. and 65% RH Steaming test (JAS special); immersed in water at room temperature for 2 hours or more Thereafter, it was steamed at 120 ° C. for 3 hours and immersed in water at room temperature until cooled, and measured in a wet state. The viscosity increase rate after 4 hours of blending was also measured.

  The present invention introduces an acetoacetyl group into a synthetic emulsion, so that the adhesiveness, adhesiveness, water resistance, boiling resistance can be obtained not only for hardwoods but also for softwood base materials that have many resins and have problems with adhesion. It was able to be set as the adhesive composition with. Since this adhesive composition is an aqueous emulsion and does not contain organic solvents in principle, it has the characteristics of low odor and environmental pollution, no formaldehyde emission, excellent workability, and long usable time. An adhesive composition could be provided.

Claims (8)

(A) A synthetic resin emulsion having an acetoacetyl group obtained by emulsion polymerization of a radically polymerizable unsaturated monomer and a radically polymerizable unsaturated monomer having an acetoacetyl group using a polysaccharide as a protective colloid; B) An adhesive composition comprising (D) a compound having an isocyanate group blended with a resin composition comprising polyvinyl alcohol and (C) a vinyl ester emulsion. (A) The radical polymerizable unsaturated monomer having an acetoacetyl group used in the synthetic resin emulsion is in the range of 1 to 15 parts by weight with respect to 100 parts by weight of the total radical polymerizable unsaturated monomer. Item 2. The adhesive composition according to Item 1. (A) The adhesive composition according to claim 1, wherein the gel fraction of the synthetic resin emulsion is 20% or more. (A) A synthetic resin emulsion having an acetoacetyl group obtained by emulsion polymerization of a radically polymerizable unsaturated monomer having a protective colloid and a radically polymerizable unsaturated monomer having an acetoacetyl group. The adhesive composition according to claim 1, wherein the adhesive composition is used in a proportion of (B) 2 to 300 parts by weight of a solid content of polyvinyl alcohol with respect to 100 parts by weight of a solid content. The adhesive composition according to claim 1, wherein (A) vinyl ester emulsion is blended in a proportion of 10 to 30 parts by weight as a solid content with respect to 100 parts by weight of a solid content of the synthetic resin emulsion. The adhesive composition according to claim 1, wherein (D) the compound having an isocyanate group is blended at a ratio of 2 to 100 parts by weight with respect to 100 parts by weight of the solid content of (A) the synthetic resin emulsion. Synthetic resin emulsion obtained by emulsion polymerization of radical polymerizable unsaturated monomer and radical polymerizable unsaturated monomer having acetoacetyl group using polysaccharide as protective colloid has polyvinyl alcohol and vinyl ester groups A method for producing an adhesive composition comprising adding a compound emulsion and mixing to obtain a resin composition, and blending a compound having an isocyanate group therein. Synthetic resin emulsion obtained by emulsion polymerization of radical polymerizable unsaturated monomer and radical polymerizable unsaturated monomer having acetoacetyl group using polysaccharide as protective colloid has polyvinyl alcohol and vinyl ester groups A coniferous wood-based plywood or wood-based laminated lumber using an adhesive composition produced by adding and mixing a compound emulsion to obtain a resin composition and blending this with a compound having an isocyanate group.