JP2009209301A - Water-resistant adhesive composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-resistant adhesive composition exhibiting a sufficient water resistant adhesion property under a heat and pressure condition, and having a stable application property or stable adhesive strength by exhibiting viscosity stable toward a temperature change. <P>SOLUTION: The water-resistant adhesive composition includes: a carboxy modified polyvinyl alcohol; a carboxy modified diene-based copolymer latex; and a polyamide epoxy resin, and is characterized in that the carboxy group content of the carboxy modified polyvinyl alcohol is 0.5-15 mol%, its degree of saponification is 70-100 mol%, its degree of polymerization is 100-3,000, and the carboxy group content of the carboxy modified diene-based copolymer latex is 0.5-10 mol%, its gel content is 20-99 mass%, and its glass transition temperature is -20 to 80&deg;C. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a water-resistant adhesive composition, and more particularly to a water-resistant adhesive composition suitable for bonding mainly with heating of a plywood or the like.

  In general, formaldehyde resins, that is, urea-formaldehyde resins, resorcinol-formaldehyde resins, melamine-formaldehyde resins, and the like are widely used as adhesives for wood from the viewpoint of water resistance and heat resistance. However, adhesives containing these formaldehyde resins release toxic formalin from the adhesive layer inside the laminated plywood into the atmosphere during the manufacturing process of the plywood or after commercialization. There was a problem. In addition, these formaldehyde resin adhesives, for example, after 30 hours at 30 ° C., the viscosity increases with the gelation of the adhesive, which may cause a decrease in coating properties or adhesive strength. But there are still challenges.

  In recent years, due to revisions to the Building Standards Law, the concentration of formaldehyde emitted from building materials used in residential buildings and the like into the atmosphere has been severely restricted, and research on adhesives that do not contain formaldehyde has been actively conducted. Yes. For example, as an adhesive that can improve water resistance and heat resistance without using formaldehyde, an isocyanate compound and a thickener or filler are blended in an aqueous solution or aqueous emulsion containing polyvinyl alcohol. A water-resistant adhesive is disclosed (for example, see Patent Document 1).

Recently, an adhesive composition for wood containing a polyamide epoxy resin (for example, see Patent Document 2) has been proposed.
Japanese Patent Publication No. 51-30576 (Claim 1) JP-A-2001-003022 (Claim 1)

  However, the invention described in Patent Document 1 has little change in viscosity due to high temperature and good apparent coatability, but the adhesive adheres to the iron press during pressing in the bonding process, and the adhesive is removed. There is a problem of causing trouble. Moreover, although the invention described in the said patent document 2 can be used suitably for adhesion | attachment of the wood which mainly uses hot pressure, such as a plywood, especially water-resistant adhesiveness is not enough.

  An object of the present invention is to provide a water-resistant adhesive composition that exhibits a sufficient water-resistant adhesive property, particularly under hot pressure.

  Another object of the present invention is to have a stable coating property or adhesive strength by exhibiting a stable viscosity due to temperature change, and excellent workability without adhesion to an iron press during pressing in the bonding process. Another object of the present invention is to provide a water resistant adhesive composition.

  The invention according to claim 1 is a water-resistant adhesive composition comprising carboxy-modified polyvinyl alcohol, carboxy-modified diene copolymer latex, and polyamide epoxy resin as essential components. The carboxyl group content is 0.5 to 15 mol%, the saponification degree is 70 to 100 mol%, the polymerization degree is 100 to 3000, and the carboxyl group content of the carboxy-modified diene copolymer latex is 0.5 to The water-resistant adhesive composition is characterized by 10 mol%, a gel content of 20 to 99 mass%, and a glass transition temperature of -20 to 80 ° C.

  The invention according to claim 2 is the invention according to claim 1, wherein the polyamide epoxy resin is reacted with an epihalohydrin to a polyamine polyamide obtained by polycondensation of a dibasic carboxylic acid compound and a polyalkylene polyamine. It is the water-resistant adhesive composition which is a polyamide epoxy resin obtained by this.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein the carboxy-modified diene copolymer latex is 10 to 10 parts by mass in solid content with respect to 100 parts by mass of the solid content contained in the carboxy-modified polyvinyl alcohol. It is a water-resistant adhesive composition containing 500 parts by mass and containing polyamide epoxy resin in a solid content of 1.0 to 100 parts by mass.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the carboxy-modified diene copolymer latex is a carboxy-modified styrene-butadiene copolymer latex. It is.

  According to the water-resistant adhesive composition of the present invention, the carboxyl group content of the carboxy-modified polyvinyl alcohol is 0.5 to 15 mol%, the saponification degree is 70 to 100 mol%, the polymerization degree is 100 to 3000, The modified diene copolymer latex has a carboxyl group content of 0.5 to 10 mol%, a gel content of 20 to 99% by mass, and a glass transition temperature of -20 to 80 ° C, which is sufficient in hot pressure. Expresses water-resistant adhesion. Therefore, it can be suitably used for bonding wood mainly composed of heat pressure such as plywood. Moreover, since the stable viscosity by a temperature change can be hold | maintained, it is excellent also in coating property and can maintain the stable adhesive strength.

  The best mode of the present invention will be described below.

  The water-resistant adhesive composition of the present invention is a water-resistant adhesive composition comprising carboxy-modified polyvinyl alcohol, a carboxy-modified diene copolymer latex, and a polyamide epoxy resin as essential components. It exhibits sufficient water-resistant adhesion under pressure conditions. For this reason, it can be suitably used for bonding wood such as plywood mainly composed of thermal pressure. Specifically, it exhibits sufficient water-resistant adhesion under general pressing conditions at a temperature of 100 to 150 ° C. A plywood that can withstand practical use can be produced. In addition, in terms of viscosity stability, a stable viscosity can be maintained even in a high temperature environment around 40 ° C., so that the coating property is excellent and a stable adhesive strength can be maintained.

  The technical reason why the water-resistant adhesive composition of the present invention exhibits sufficient water-resistant adhesion at a hot pressure of 100 to 150 ° C. is not necessarily clear, but it is likely that the carboxy-modified polyvinyl alcohol and the carboxy-modified diene-based copolymer It is inferred that the curing reaction occurs in concert between the polymer latex and the polyamide epoxy resin.

  The carboxy-modified polyvinyl alcohol that is one of the components of the water-resistant adhesive composition of the present invention refers to a polyvinyl alcohol polymer having a carboxyl group in the molecule. This polyvinyl alcohol polymer is obtained by, for example, a method in which a vinyl ester monomer is copolymerized with an ethylenically unsaturated carboxylic acid or its acid anhydride and then saponified (random copolymer), or a thiol group at the end. It can be obtained by a method of radical polymerization (block polymer) of the above ethylenically unsaturated carboxylic acid or its acid anhydride in the presence of a polyvinyl alcohol polymer having the above.

  Examples of the vinyl ester monomer include vinyl acetate, vinyl formate, and vinyl propionate. Examples of the ethylenically unsaturated carboxylic acid and its acid anhydride include acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, fumaric acid, and maleic anhydride. In the copolymerization, other copolymerizable monomers that can be copolymerized within a range not impairing the object of the present invention, for example, ethylene, isobutylene, acrylonitrile, methacrylonitrile, vinyl chloride, vinyl fluoride, and the like may be used.

  The carboxyl group content of the carboxy-modified polyvinyl alcohol used in the present invention, that is, the carboxyl group-modified amount is in the range of 0.5 to 15 mol%. If the carboxyl group modification amount is less than 0.5 mol%, sufficient crosslinking density cannot be obtained, and it is difficult to improve water resistance, heat resistance and boiling resistance. On the other hand, if it exceeds 15 mol%, generally, It is difficult to obtain good polyvinyl alcohol due to lack of stability during synthesis. Of these, the carboxyl group modification amount is preferably in the range of 1.0 to 10 mol%. The saponification degree of the carboxy-modified polyvinyl alcohol is in the range of 70 to 100 mol%. If the degree of saponification is out of this range, conditions such as sufficient water resistance, heat resistance, and boiling resistance are difficult to improve. Of these, the saponification degree is preferably in the range of 80 to 99 mol%. Furthermore, the polymerization degree of the carboxy-modified polyvinyl alcohol is in the range of 100 to 3000. If the degree of polymerization is less than 100, sufficient water resistance, heat resistance and boiling resistance are difficult to improve. On the other hand, if it exceeds 3000, generally good polyvinyl alcohol lacking stability during synthesis of polyvinyl alcohol can be obtained. hard. Among these, it is preferable that a polymerization degree exists in the range of 500-2500.

  The carboxy-modified diene copolymer latex that is one of the components of the water-resistant adhesive composition of the present invention generally comprises an ethylenically unsaturated carboxylic acid monomer and a conjugated diene monomer. It is prepared by copolymerizing monomers containing it.

  Examples of the ethylenically unsaturated carboxylic acid monomer include itaconic acid, acrylic acid, methacrylic acid, fumaric acid, maleic acid and the like. Examples of the conjugated diene monomer include 1,3-butadiene, 2-methyl-1,3-butadiene, 2-chloro-1,3-butadiene, and the like. Among these, 1,3-butadiene is most preferable from the viewpoint of versatility and cost. These conjugated diene monomers are essential for imparting toughness to the latex film and obtaining high adhesive strength. In addition to the above two types of monomers, for example, aromatic vinyl monomers represented by styrene, vinyl cyanide monomers such as acrylonitrile and methacrylonitrile, ethyl acrylate, butyl acrylate, acrylic acid (Meth) acrylic acid ester monomers such as 2-ethylhexyl, methyl methacrylate and butyl methacrylate can be used. Usually, various vinyl monomers having a functional group such as a hydroxyl group, an amide group, an amino group, a methylol group, a glycidyl group, a sulfonic acid group, and a phosphoric acid group in a range of 5% by mass or less are used as necessary. The

  Examples of the carboxy-modified diene copolymer latex suitable for the present invention include carboxy-modified styrene-butadiene copolymer latex obtained by being prepared by copolymerization mainly composed of styrene and butadiene. In the present invention, the reason why the carboxy-modified styrene-butadiene copolymer latex is preferably selected is that it is suitable for developing excellent adhesive strength and is desirable from the viewpoint of versatility and cost. The typical constitution of each monomer component in the carboxy-modified styrene-butadiene copolymer latex is 0.5 to 10% by mass of ethylenically unsaturated carboxylic acid monomer, 20 to 70% by mass of 1,3-butadiene, They are 10-79.5 mass% of styrene and 0-50 mass% of vinyl monomers copolymerizable with these. A particularly preferred ratio of the ethylenically unsaturated carboxylic acid monomer is 1.0 to 8% by mass. Other suitable carboxy-modified diene copolymer latexes in the present invention include carboxy-modified styrene-isoprene copolymer latex.

  The carboxy-modified diene copolymer latex used in the present invention is not particularly limited and is prepared by a known emulsion polymerization method. For example, in the dispersion system having the monomer, chain transfer agent, surfactant, radical polymerization initiator, and other additive components used as necessary as basic constituent components, the monomer is polymerized, It is prepared by a method for producing an aqueous dispersion of synthetic resin particles, that is, a latex. The solid content concentration in the latex is selected in the range of 40 to 60% by mass, and the average particle size is preferably in the range of 40 to 400 nm, particularly preferably in the range of 50 to 200 nm. . The chain transfer agent is used to adjust the molecular weight and gel generation amount of the carboxy-modified diene copolymer latex polymer. For example, those that can be used in usual emulsion polymerization such as mercaptans such as n-hexyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, thioglycolic acid, and α-methylstyrene dimer can be used.

  The carboxyl group content of the carboxy-modified diene copolymer latex used in the present invention is in the range of 0.5 to 10 mol%. If it is less than the lower limit, problems such as a decrease in adhesive strength and lack of stability of the latex occur, and if it exceeds the upper limit, excessive thickening occurs in both the latex and, in some cases, the adhesive composition. Among these, it is preferable that carboxyl group content exists in the range of 1-8 mol%.

  The gel content of the carboxy-modified diene copolymer latex is in the range of 20 to 99% by mass. When it is out of the above range, the water-resistant adhesive strength is particularly lowered. Among these, it is preferable that a gel content rate exists in the range of 30-90 mass%.

  The range of the glass transition temperature of the carboxy-modified diene copolymer latex is -20 to 80 ° C. When the glass transition temperature is out of the above range, the water-resistant adhesive strength is lowered in addition to the normal adhesive strength.

  Examples of the polyamide epoxy resin that is one of the components of the water-resistant adhesive composition of the present invention include resins obtained by reacting polyamine polyamides with epihalohydrin. Here, examples of the polyamine polyamides include polycondensates obtained by a polycondensation reaction between a dibasic carboxylic acid compound and a polyalkylene polyamine.

  The dibasic carboxylic acid compound used in the polyamine polyamides is a derivative such as dicarboxylic acid and its ester or acid anhydride. Examples of dicarboxylic acids include dicarboxylic acids such as aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid and adipic acid, and aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid, and sodium and potassium dicarboxylic acids. And the like. As dicarboxylic acids, two or more different dicarboxylic acids may be mixed and used. Among them, aliphatic dicarboxylic acids having about 3 to 10 carbon atoms are preferable, and adipic acid is particularly preferable industrially.

  Examples of polyalkylene polyamines used for polyamine polyamides include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, iminobispropylamine, and the like. As polyalkylene polyamines, two or more different types of polyalkylene polyamines may be mixed and used. Among the polyalkylenepolyamines, diethylenetriamine and triethylenetetramine are preferable. In the polycondensation reaction to give polyamine polyamides, the dicarboxylic acids are usually about 0.9 to 1.4 equivalents, preferably about 0.9 to 1.2 equivalents, based on 1 equivalent of the terminal amino group of the polyalkylene polyamines. use. In the polycondensation reaction, aminocarboxylic acids and diamines may be used in combination. Examples of aminocarboxylic acids include aminocarboxylic acids such as glycine, alanine, and aminocaproic acid and esters thereof, and lactams such as caprolactam. Examples of diamines include ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, 1,6-hexanediamine, and the like. Examples of the polycondensation reaction include a method of removing generated water or alcohol out of the system at a reaction temperature of about 50 to 250 ° C. under normal pressure or reduced pressure.

  Next, the aqueous solution of polyamine polyamides obtained by the polycondensation reaction is subjected to a reaction with epihalohydrin. Examples of the epihalohydrin used here include epichlorohydrin and epibromohydrin, among which epichlorohydrin is preferred. The reaction between polyamine polyamides and epihalohydrin is carried out in an aqueous solution having a resin concentration of about 10 to 70% by mass, preferably 20 to 60% by mass. In the reaction of polyamine polyamides with epihalohydrin, about 0.85-2 mol, preferably about 1-1.8 mol of epihalohydrin is usually used for 1 equivalent of intramolecular amino group of polyamine polyamide.

  The water-resistant adhesive composition of the present invention is prepared by first thoroughly mixing carboxy-modified polyvinyl alcohol and carboxy-modified diene copolymer latex to prepare a hydrous acid composition, and then adding the hydrous acid composition to the hydrous acid composition. It is performed by mixing polyamide epoxy resin.

  The addition amount of the carboxy-modified diene copolymer latex is preferably 10 to 500 parts by mass, more preferably 50 to 250 parts by mass with respect to 100 parts by mass of the solid content of the carboxy-modified polyvinyl alcohol. is there. This is because when the amount of the carboxy-modified diene copolymer latex is out of the above range, the water-resistant adhesive strength tends to decrease.

  The amount of the polyamide epoxy resin added is preferably 1.0 to 100 parts by mass, more preferably 5 to 70 parts by mass with respect to 100 parts by mass of the carboxy-modified polyvinyl alcohol. This is because when the amount of the polyamide epoxy resin is outside the above range, the water-resistant adhesive strength is particularly likely to decrease.

  Next, examples of the present invention will be described together with comparative examples.

<Example 1>
100 parts by mass of an aqueous solution containing 15% by mass of carboxy-modified polyvinyl alcohol (carboxyl group content 5.5 mol%, saponification degree 98 mol%, polymerization degree 1700), and carboxy-modified styrene-butadiene having a solid content concentration of 50% by mass Copolymer latex (carboxyl group content 2 mol%, gel content 87 mass%, glass transition temperature 20 ° C) 45 parts by mass was sufficiently mixed to obtain a hydrous acid composition. To the water-dispersed composition, 12 parts by mass of a polyamide epoxy resin (trade name Sumire's resin 675 manufactured by Sumitomo Chemical Co., Ltd., concentration: 25% by mass) was mixed to prepare a water-resistant adhesive composition of the present application. The composition of the prepared water resistant adhesive composition is shown in Table 1 below. The blending ratio (parts by mass) of carboxy-modified polyvinyl alcohol, carboxy-modified styrene-butadiene copolymer latex and polyamide epoxy resin in this adhesive composition is 100: 150: 20 on a solid basis. In addition, the obtained adhesive composition did not show any increase in viscosity or gelation when allowed to stand at room temperature (20 ° C.) for at least 10 hours and had good standing stability.

Subsequently, a hardwood plywood having a thickness of 4.0 mm and a single-layered south sea wood veneer having a thickness of 1.3 mm were prepared, and the prepared adhesive composition was applied to one side of the plywood at an application amount of 250 g / m ² . . These plywood and single plate are overlapped and pressed for 20 minutes under a cold pressure condition at a temperature of 20 ° C. and a pressure of 1.2 MPa, and then heated for 1 minute at a temperature of 120 ° C. and a pressure of 0.79 MPa (8 kg / cm ² ). After bonding, a square test piece having a side of 75 mm was prepared.

<Example 2>
A water resistant adhesive composition was prepared in the same manner as in Example 1 except that carboxy-modified polyvinyl alcohol having a carboxyl group content of 5.5 mol%, a saponification degree of 99 mol%, and a polymerization degree of 1500 was used. Obtained. The composition of the prepared water resistant adhesive composition is shown in Table 1 below.

<Example 3>
Carboxy-modified polyvinyl alcohol having a carboxyl group content of 2 mol%, a saponification degree of 98 mol%, and a polymerization degree of 1700, and a carboxyl group content of 5 mol%, a gel content of 87% by mass, and a glass transition temperature of 20 ° C. A water-resistant adhesive composition was prepared in the same manner as in Example 1 except that a water-acid composition was obtained using a copolymer latex, and a test piece was obtained. The composition of the prepared water resistant adhesive composition is shown in Table 1 below.

<Example 4>
The same as Example 3 except that a hydrated acid composition was obtained using a carboxy-modified styrene-butadiene copolymer latex having a carboxyl group content of 2 mol%, a gel content of 30 mass%, and a glass transition temperature of 70 ° C. A water resistant adhesive composition was prepared to obtain a test piece. The composition of the prepared water resistant adhesive composition is shown in Table 1 below.

<Example 5>
Instead of the carboxy-modified styrene-butadiene copolymer latex, a carboxy-modified styrene-isoprene copolymer latex having a carboxyl group content of 2 mol%, a gel content of 87% by mass, and a glass transition temperature of -10 ° C was used. A water resistant adhesive composition was prepared in the same manner as in Example 3 except that the composition was obtained, and a test piece was obtained. The composition of the prepared water resistant adhesive composition is shown in Table 1 below.

<Example 6>
A moist acid composition was obtained using a carboxyl-modified styrene-butadiene copolymer latex having a carboxyl group content of 2 mol%, a gel content of 87 mass%, and a glass transition temperature of 20 ° C, and the amount of polyamide epoxy resin added A water-resistant adhesive composition was prepared in the same manner as in Example 3 except that 3.0 parts by mass was obtained, and a test piece was obtained. The composition of the prepared water resistant adhesive composition is shown in Table 1 below. In addition, the mixture ratio (mass part) of the carboxy modified polyvinyl alcohol, the carboxy modified styrene-butadiene copolymer latex, and the polyamide epoxy resin in the prepared adhesive composition is 100: 150: 5 based on the solid content.

<Example 7>
Hydrous acid composition with an addition amount of carboxy-modified styrene-butadiene copolymer latex (carboxyl group content 2 mol%, gel content 87 mass%, glass transition temperature 20 ° C.) having a solid content concentration of 50 mass% as 15 mass parts A water-resistant adhesive composition was prepared and a test piece was obtained in the same manner as in Example 3 except that the product was obtained and that the addition amount of the polyamide epoxy resin was 18 parts by mass. The composition of the prepared water resistant adhesive composition is shown in Table 1 below. In addition, the mixture ratio (mass part) of the carboxy modified polyvinyl alcohol, the carboxy modified styrene-butadiene copolymer latex, and the polyamide epoxy resin in the prepared adhesive composition is 100: 50: 30 based on the solid content.

<Example 8>
Hydrous acid composition with an addition amount of carboxy-modified styrene-butadiene copolymer latex (carboxyl group content 2 mol%, gel content 87 mass%, glass transition temperature 20 ° C.) having a solid content concentration of 50 mass% as 75 mass parts A water-resistant adhesive composition was prepared and a test piece was obtained in the same manner as in Example 3 except that the product was obtained and that the amount of polyamide epoxy resin added was 42 parts by mass. The composition of the prepared water resistant adhesive composition is shown in Table 1 below. In addition, the mixture ratio (mass part) of the carboxy modified polyvinyl alcohol, the carboxy modified styrene-butadiene copolymer latex, and the polyamide epoxy resin in the prepared adhesive composition is 100: 250: 70 based on the solid content.

<Comparative Example 1>
Example 1 except that a non-carboxy modified polyvinyl alcohol having a carboxyl group content of 0 mol%, a saponification degree of 98 mol%, and a polymerization degree of 1700 was used instead of the carboxy modified polyvinyl alcohol to obtain a hydrous acid composition. Similarly, a water resistant adhesive composition was prepared to obtain a test piece. The composition of the prepared water resistant adhesive composition is shown in Table 1 below.

<Comparative Example 2>
A water-resistant adhesive as in Example 1 except that a hydrated acid composition was obtained using carboxy-modified polyvinyl alcohol having a carboxyl group content of 5.5 mol%, a saponification degree of 40 mol%, and a polymerization degree of 1500. A composition was prepared to obtain a test piece. The composition of the prepared water resistant adhesive composition is shown in Table 1 below.

<Comparative Example 3>
A water-resistant adhesive as in Example 1 except that a hydrated acid composition was obtained using carboxy-modified polyvinyl alcohol having a carboxyl group content of 5.5 mol%, a saponification degree of 99 mol%, and a polymerization degree of 70. A composition was prepared. The composition of the prepared water resistant adhesive composition is shown in Table 1 below. An attempt was made to make a test piece using this water-resistant adhesive composition, but due to the extremely low viscosity of the water-resistant adhesive composition and the occurrence of a chipped portion in the adhesive layer, an appropriate test piece could not be produced. It was.

<Comparative example 4>
Instead of the carboxy-modified styrene-butadiene copolymer latex, a non-carboxy-modified styrene-butadiene copolymer latex having a carboxyl group content of 0 mol%, a gel content of 80% by mass, and a glass transition temperature of 20 ° C. was used. A water resistant adhesive composition was prepared in the same manner as in Example 3 except that the composition was obtained, and a test piece was obtained. The composition of the prepared water resistant adhesive composition is shown in Table 1 below.

<Comparative Example 5>
The same as Example 3 except that a hydrated acid composition was obtained using a carboxy-modified styrene-butadiene copolymer latex having a carboxyl group content of 2 mol%, a gel content of 15 mass%, and a glass transition temperature of 0 ° C. A water resistant adhesive composition was prepared to obtain a test piece. The composition of the prepared water resistant adhesive composition is shown in Table 1 below.

<Comparative Example 6>
The same as Example 3 except that a hydrated acid composition was obtained using a carboxy-modified styrene-butadiene copolymer latex having a carboxyl group content of 2 mol%, a gel content of 87 mass%, and a glass transition temperature of 90 ° C. A water resistant adhesive composition was prepared to obtain a test piece. The composition of the prepared water resistant adhesive composition is shown in Table 1 below.

<Comparative Example 7>
A water-resistant adhesive composition was prepared and tested in the same manner as in Example 3 except that no carboxy-modified styrene-butadiene copolymer latex was added and that the polyamide epoxy resin was 11.5 parts by mass. I got a piece. The composition of the prepared water resistant adhesive composition is shown in Table 1 below. In addition, the mixture ratio (mass part) of the carboxy modified polyvinyl alcohol, the carboxy modified diene copolymer latex, and the polyamide epoxy resin in the prepared adhesive composition is 100: 0: 19.2 based on the solid content.

<Comparison test and evaluation>
About each test piece produced in Examples 1-8, Comparative Examples 1 and 2, and Comparative Examples 4-7, it heat-resistant water and boil-proof-process, and each adhere | attaches by the Class I immersion peeling test prescribed | regulated to JAS normal plywood specification The performance was examined. The results are shown in Table 2 below. The hot water resistant treatment is performed under the condition that the test piece is immersed in warm water at 70 ° C. for 2 hours and then dried at a temperature of 60 ± 3 ° C. for 3 hours, and the peeled state of the test piece after the treatment is determined. In the boiling resistance treatment, the test piece is immersed in boiling water for 4 hours, dried at a temperature of 60 ± 3 ° C. for 20 hours, then immersed in boiling water for 4 hours, and further dried at 60 ± 3 ° C. for 3 hours. The peeled state of the test piece after this treatment is determined. In addition, the Class I immersion peel test acceptance standard prescribed in the JAS ordinary plywood standard is the peel rate, that is, the part where the same adhesive layer of the test piece peels is 1/3 (33.3%) of the length of each side surface. Is less than.

  As is clear from Table 2, when Examples 1 to 8, Comparative Examples 1 and 2 and Comparative Examples 4 to 7 are compared, Examples 1 to 8 are both in the pickling peeling test by the hot water resistant treatment and the boiling resistant treatment. It was confirmed that the peeling rate was lower than those of Comparative Examples 1 and 2 and Comparative Examples 4 to 7, and excellent adhesiveness was exhibited. In Comparative Examples 1 and 5, it was confirmed that high adhesion reaching the acceptance standard was exhibited in the pickling peeling test by the hot water resistant treatment, but the passing standard was not reached in the pickling peeling test by the boiling resistance treatment. Moreover, in Comparative Example 2, although it was confirmed that high adhesion reaching the acceptance standard was exhibited in both the pickling peeling test by the hot water resistant treatment and the boiling resistant treatment, it did not reach Examples 1-8. Furthermore, in Comparative Example 3, since the viscosity of the water-resistant adhesive composition was extremely low and a chipped portion was generated in the adhesive layer, an appropriate test piece could not be produced.

  The water-resistant adhesive composition of the present invention exhibits a sufficient water-resistant adhesive property under hot pressure conditions, and has a stable coating property or adhesive strength by exhibiting a stable viscosity due to a temperature change. It can be suitably used as an adhesive for wood mainly composed of hot pressure.

Claims (4)

A water-resistant adhesive composition comprising carboxy-modified polyvinyl alcohol, carboxy-modified diene copolymer latex, and polyamide epoxy resin as essential components,
The carboxyl group content of the carboxy-modified polyvinyl alcohol is 0.5 to 15 mol%, the saponification degree is 70 to 100 mol%, and the polymerization degree is 100 to 3000,
The carboxyl group-containing diene copolymer latex has a carboxyl group content of 0.5 to 10 mol%, a gel content of 20 to 99 mass%, and a glass transition temperature of -20 to 80 ° C. Adhesive composition.   The water-resistant adhesive composition according to claim 1, wherein the polyamide epoxy resin is a polyamide epoxy resin obtained by reacting a polyamine polyamide obtained by polycondensation of a dibasic carboxylic acid compound and a polyalkylene polyamine with an epihalohydrin. object. 10 to 500 parts by mass of carboxy-modified diene copolymer latex in solid content with respect to 100 parts by mass of solid content contained in carboxy-modified polyvinyl alcohol,
The water-resistant adhesive composition according to claim 1 or 2, comprising a polyamide epoxy resin in a solid content of 1.0 to 100 parts by mass.   The water-resistant adhesive composition according to any one of claims 1 to 3, wherein the carboxy-modified diene copolymer latex is a carboxy-modified styrene-butadiene copolymer latex.