JP2000038548A - Resin composition and adhesive using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a curable resin composition for adhesives which does not adversely affect a human body and the environment and is safe as an adhesive for wood for use in construction materials, and furniture and the like and has the performance of a small reduction in adhesion against high temperature hot water. SOLUTION: This curable resin composition is obtained by adjusting the pH of a mixture comprising, as the protective colloid, a vinyl acetate based polymer emulsion using a modified polyvinyl alcohol whose hydroxyl groups have been partially acetoacetoxylated and an unsaturated (meth)acrylate having two or more (meth)acryloyl groups in the molecule or comprising, in addition to these two components, calcium carbonate to 8 or more. An adhesive for wood is composed of the curable resin composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a curable resin composition which is useful mainly as an adhesive for wood used in an aqueous solution or emulsion state, and has a modified acetoacetoxy part of a hydroxy group as a protective colloid. Vinyl acetate polymer emulsion using polyvinyl alcohol (also simply referred to as "modified polyvinyl alcohol" in the present invention) and unsaturated (meth) acrylate having more than one (meth) acryloyl group in one molecule Or an adhesive comprising these and calcium carbonate, particularly an excellent curable resin composition as an adhesive for materials such as wood.

[0002]

2. Description of the Related Art In recent years, various disorders of the human body due to chemical substances, for example, so-called allergic symptoms and diseases such as asthma and dermatitis have been increasing and have been widely taken up as a social problem. Adhesives containing formaldehyde as a component of wood adhesives as one of the causes of these symptoms and diseases, such as phenolic resins, urea resins, melamine resins, etc., can cure small amounts of free formaldehyde even after curing. A small amount of formaldehyde is generated from building materials, furniture, and furnishings using these adhesives, and it is said that the above-mentioned allergic diseases are caused by this. At the moment, wood-based adhesives that do not use formaldehyde at all
Practically, an emulsion-type adhesive containing polyvinyl acetate or ethylene-vinyl acetate copolymer resin containing polyvinyl alcohol as a protective colloid, and a so-called aqueous vinyl urethane in which diisocyanate is used in combination with latex of SBR and polyvinyl alcohol. It is no exaggeration to say that there are only two systems of this type.

[0003] A vinyl acetate resin emulsion or a urea resin is also used for general plywood which does not require high water resistance. However, these adhesives are used in fields which must pass a hot water resistance test such as first class plywood. Is difficult to use. On the other hand, aqueous vinyl urethanes use a diisocyanate, and in some cases, a water-insoluble solvent must be used in combination, if necessary, and are not necessarily environmentally friendly adhesives. That is, at this stage, it can be said that there is no adhesive that has no adverse effect on the human body in any of its use methods and products.

[0004]

SUMMARY OF THE INVENTION The present invention has no adverse effect on the human body and the environment, is safe as a wood adhesive for building materials and furniture, and can be used in high-temperature hot water. On the other hand, an object of the present invention is to develop a curable resin composition for an adhesive having a performance with little decrease in adhesive strength.

[0005]

Means for Solving the Problems The present inventors have conducted various studies on various materials in order to achieve the above object, and have found that the following curable resin composition can achieve the above object. The present invention has been completed. That is, the present invention provides [1] (1) a vinyl acetate-based polymer emulsion using a modified polyvinyl alcohol in which a part of a hydroxy group is acetoacetoxylated as a protective colloid, and (2) more than one in a molecule. A mixture of an unsaturated (meth) acrylate having a (meth) acryloyl group and a curable resin composition having a pH adjusted to 8 or more;

[2] The curable resin composition according to the above [1], wherein the modified polyvinyl alcohol in which a part of the hydroxy group is acetoacetoxylated has an acetoacetoxylation ratio with respect to the hydroxy group of 3 to 10 mol%. [3]
More than one (meth) per molecule per 1 mol of acetoacetoxy groups in the vinyl acetate polymer emulsion
The curable resin composition according to the above [1], wherein the α, β-unsaturated group in the unsaturated (meth) acrylate having an acryloyl group is blended in a range of 0.1 to 1 mol, [4] curable resin composition The curable resin composition according to any one of the above [1] to [3], wherein the resin composition further contains calcium carbonate, [5] the amount of calcium carbonate used is 100% of the solid content of the vinyl acetate polymer emulsion. 1 for parts by weight
The curable resin composition according to any one of the above [1] to [4], and [6] the curable resin according to any one of the above [1] to [5]. The above object has been achieved by developing an adhesive for wood comprising the composition.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a vinyl acetate polymer emulsion using a modified polyvinyl alcohol in which a part of hydroxy groups are acetoacetoxylated as a protective colloid, and more than one (meth) acryloyl in one molecule. An unsaturated (meth) acrylate having a group, or a curable resin composition obtained by using the same together with calcium carbonate and adjusting the pH to 8 or more, and a wood adhesive using the same. In the present invention, the modified polyvinyl alcohol used as the protective colloid of the polymer emulsion is a known compound, and can be produced by a known method (reaction between polyvinyl alcohol and diketene: see, for example, JP-A-55-94904). Although it is possible, a commercially available product may be used. In general, those having an acetoacetoxylation in the range of 3 mol% to 10 mol%, preferably 5 mol% to 10 mol% of the hydroxy groups of the polyvinyl alcohol can be conveniently used in the present invention.

The polymer emulsion which can be used in the resin composition of the present invention is a polymer emulsion of vinyl acetate alone using a modified polyvinyl alcohol as a protective colloid, or a copolymer emulsion containing a comonomer copolymerizable with vinyl acetate as required. It is.
The comonomer in this case does not need to be particularly limited as long as it can be copolymerized. For example, vinyl propionate,
Examples thereof include vinyl versatate, ethylene, acrylates, and methacrylates.

[0009] In particular, a monomer containing an acetoacetoxy group and an unsaturated group as a comonomer is a particularly desirable embodiment because the polymer containing the monomer may also crosslink. As a comonomer containing these acetoacetoxy groups and unsaturated groups, acetoacetoxyethyl acrylate,
Examples include unsaturated acetoacetoxylated monomers such as acetoacetoxyethyl methacrylate and acetoacetoxylated allyl alcohol, which sufficiently achieve the object of the present invention. The unsaturated acetoacetoxylated monomer is used in an amount of 0.1 mol% or more and 30 mol% or less based on all monomers of the polymer emulsion. 0.1
If the amount is less than mol%, there is no effect of using the comonomer, and if the amount is more than 30 mol%, the physical properties are not improved and the cost is merely increased. In particular, use in the range of 1 mol% to 20 mol% is preferred. A vinyl acetate-based polymer emulsion using modified polyvinyl alcohol as a protective colloid can be produced by emulsion polymerization using vinyl acetate alone or in combination with the above comonomers in a conventional manner.

Unsaturated (meta) used in the present invention
Acrylate is more than one (meth) in one molecule
It has an acryloyl group, preferably two or more (meth) acryloyl groups. Unsaturated (meth) acrylates vary depending on reaction conditions and cannot be unconditionally determined, but generally have one (meth) acryloyl group in one molecule, two or more (meth) acrylates in one molecule It is a mixture of those having an acryloyl group and those having no (meth) acryloyl group. Therefore, the term “unsaturated (meth) acrylate having more than one (meth) acryloyl group in one molecule” in the present invention means the average value of the (meth) acryloyl group in the mixture. Unsaturated (meth) acrylate having more than one (meth) acryloyl group in one molecule used in the resin composition of the present invention (in the present invention, it may be simply referred to as "unsaturated (meth) acrylate") ) Includes: i) vinyl ester (epoxy (meth) acrylate), ii) unsaturated urethane- (meth) acrylate, ii.
i) polyester- (meth) acrylate, iv) polyhydric alcohol- (meth) acrylate (polyol- (meth)
Acrylate). These unsaturated (meth) acrylates act as a crosslinking agent for acetoacetoxy groups in a polymer emulsion or a modified polyvinyl alcohol which is originally water-soluble or water-dispersible, and make them insoluble in hot water.

I) Vinyl ester (epoxy (meth) acrylate) A vinyl ester can be obtained by reacting an epoxy resin with an α, β-unsaturated monobasic acid, and is excellent in water resistance and chemical resistance. Since it is a resin having good strength and excellent adhesive strength, it is widely used as a resin for fiber-reinforced plastic or a resin for solder resist requiring heat resistance. It is also an excellent material as a component of wood adhesive. In particular, when reacted with a water-soluble denatured polyvinyl alcohol, it has a specific action such as rendering the water-soluble denatured polyvinyl alcohol insoluble in hot water. In the present invention, both a compound obtained by blending a polyfunctional monomer with a vinyl ester and a compound not formulated are referred to as a vinyl ester.

Epoxy resins used for producing vinyl esters are roughly classified into so-called "epi-bis type" having a bisphenol structure and "novolak epoxy type" having a novolak structure. Examples include a “glycidyl ether type” having a structure, a “glycidyl ether type” of a polyether polyol, and a “glycidyl ether type” of a 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 the α, β-unsaturated monobasic acid to be reacted with an epoxy resin to form a vinyl ester include acrylic acid, methacrylic acid (hereinafter, both are referred to as “(meth) acrylic acid”), crotonic acid, and maleic acid. Monoesters, fumaric acid monoesters, itaconic acid monoesters and the like can be mentioned, and they are selected as needed according to required physical properties and the curing speed of the resin. Generally, the use of (meth) acrylic acid is convenient.

The reaction between the epoxy resin and the α, β-unsaturated monobasic acid is usually carried out in a stream of air (oxygen) in the presence of tertiary amines, quaternary ammoniums, quaternary ammonium salts, triphenylphosphine, etc. 100 to 14 in the presence of a catalyst
Heating to 0 ° C is performed. Reactive diluent as needed,
For example, the reaction can be carried out in the presence of a polyhydric alcohol- (meth) acrylate. In this case, the reactive diluent can be used as it is as a crosslinking agent for the modified polyvinyl alcohol. There is no particular limitation on the type and amount of the reactive diluent that can be used in the present invention. However, when used for wood bonding or the like that requires hot water resistance, vinyl ester and polyhydric alcohol- (meth) The amount of the vinyl ester is at least 10% based on the total amount of the acrylate.
% By weight, and preferably 50% by weight or more. The polyhydric alcohol- (meth) acrylate can be obtained by performing an ester reaction between the polyhydric alcohol and (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, and glycerin. And a pentaery slit.

Ii) Unsaturated urethane- (meth) acrylates There are several types of unsaturated urethane- (meth) acrylates. Typically, they have a (meth) acryloyl group and a hydroxyl group in the same molecule. With unsaturated alcohols,
It is synthesized in combination with isocyanates and, if necessary, a polyhydric hydroxyl compound or a polymer having a hydroxyl group. In addition, it is also synthesized by a reaction between an unsaturated isocyanate and a polyhydric hydroxyl compound.

Examples of the unsaturated alcohol include 2-hydroxyethyl acrylate having a (meth) acryloyl group and a hydroxyl group in the same molecule.
Examples thereof include 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and hydroxypolyethylene glycol mono (meth) acrylate, which are sufficient for the purpose of the present invention.

The type of isocyanate to be reacted with the unsaturated alcohol is not particularly limited, but a commercially available type can be used as it is. For example,
2,4-tolylene diisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate And naphthalene, hydrogenated diphenylmethane diisocyanate, and trimers thereof.

Examples of the polyvalent hydroxyl compound or the polymer having a hydroxyl group include ethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol, bisphenol A-ethylene oxide adduct, bisphenol A-propylene oxide adduct, polyethylene glycol, Examples include polyhydric alcohols such as polypropylene glycol, trimethylolpropane, glycerin, and pentaerythritol, polyethers, hydroxypolyesters, and polybutadienes having a hydroxyl group.

Examples of the unsaturated isocyanate include isocyanate ethyl acrylate, isocyanate ethyl methacrylate and methacryl isocyanate.

The synthesis reaction of the unsaturated urethane- (meth) acrylate is carried out in a small amount of a dehydrated hydrophilic solvent or a low-viscosity polyfunctional acrylate. After the completion of the reaction, the compound is directly mixed into an emulsion.

Iii) Polyester- (meth) acrylate A compound or an oligomer thereof which shares an ester bond in the main chain of a constituent molecule and a (meth) acryloyl group in the same molecule is called polyester- (meth) acrylate. Generally, a polyhydric alcohol, a polybasic acid (or an acid anhydride thereof), and (meth) acrylic acid are mixed, and an esterification catalyst such as sulfuric acid and p-toluenesulfonic acid, and water such as benzene and toluene can be azeotropically removed. It is obtained by esterification in the presence of a solvent, and further washed with water and the solvent is distilled off to obtain a resin. Various kinds of polyester- (meth) acrylates are synthesized by selecting the kind and blending ratio of polyhydric alcohol and polybasic acid (or acid anhydride thereof).

As the kind of the polyhydric alcohol, those similar to those used in synthesizing the unsaturated urethane- (meth) acrylate can be used.

Iv) Polyhydric alcohol- (meth) acrylate (polyol- (meth) acrylate) Obtained by esterifying a polyhydric alcohol and (meth) acrylic acid in the same manner as polyester- (meth) acrylate. Examples of the polyhydric alcohol include those similar to those used when synthesizing the unsaturated urethane- (meth) acrylate.

The modified polyvinyl alcohol is water-soluble, and is generally used in the form of an aqueous solution for producing a vinyl acetate polymer emulsion, and the unsaturated (meth) acrylate is used in the form of an emulsion for mixing with the emulsion. Is preferred, but need not be used in the form of an emulsion. In addition, unsaturated (meth) acrylate is 2
You may mix and use more than one kind. As the emulsifier for emulsification, various surfactants and polyvinyl alcohol can be used, but from the viewpoint of emulsion stability, partially saponified polyvinyl alcohol is preferable as the polyvinyl alcohol.

The amount of the unsaturated (meth) acrylate used in the polymer emulsion needs to be changed according to the purpose. Generally, the amount of the unsaturated (meth) acrylate is based on 1 mol of acetoacetoxy groups in the polymer emulsion. 0.1 mol or more of the total α, β-unsaturated groups in the acrylate is required. If the amount of the α, β-unsaturated group is less than 0.1 mol, the crosslinking reaction with the acetoacetoxy group is not sufficiently performed, and only those having insufficient physical properties are obtained. From the viewpoint of the crosslinking reaction, the amount of the α, β-unsaturated group is not more than 1 mol, but in the case of heat pressure, polymerization of unsaturated groups can be expected, which is useful for improving the adhesive strength. It is permissible to use more than. The proportion of the modified polyvinyl alcohol used in the production of the polymer emulsion may be within the range of the usual amount of the protective colloid used. For example, 0.5 to 20% by weight of the modified polyvinyl alcohol is used as the modified polyvinyl alcohol per monomer. When the amount used is less than 0.5% by weight, the adhesive strength after boiling is greatly reduced, and when the amount is more than 20% by weight, the adhesive strength is improved even if the amount is further increased. Absent. The preferred range is 5 to 15% by weight.

In the present invention, it is necessary to adjust the pH of the mixed resin composition to 8 or more in order to promote the reaction between the acetoacetoxy group and the α, β-unsaturated group. pH
The higher the pH of the adhesive, the faster the addition reaction proceeds. However, for example, if the pH of the adhesive is too high, defects such as contamination of the adherend, reduction in heat resistance, and danger in handling may occur. Should be. If the pH is less than 8, sufficient physical property values cannot be obtained within a practical period.
When H exceeds 12, the above-mentioned drawbacks tend to occur.

The pH of the resin composition is adjusted by adjusting the hydroxide of an alkali metal, the hydroxide of an alkaline earth metal, the alkali metal salt of silicic acid, the alkaline earth metal salt of silicic acid, and the quaternary ammonium hydroxide. The type does not need to be particularly limited, but considering cost, coloring, etc., lithium,
Representative examples include sodium or potassium hydroxide, lithium silicate, sodium silicate, and tetramethylammonium hydroxide.

As described above, a mixture of a vinyl acetate-based polymer emulsion using a modified polyvinyl alcohol as a protective colloid and an unsaturated (meth) acrylate can provide a sufficient adhesive strength even with a resin composition whose pH is adjusted to 8 or more. Although it becomes an adhesive having, the resin composition further combined with calcium carbonate further improved the adhesive strength,
It has been found that there is no variation in the adhesive strength and that the adhesive has a stable adhesive strength.

In the present invention, when calcium carbonate is used in combination, it is not clear why the adhesive strength is improved, the adhesive strength does not vary, and the adhesive strength is stable. A chelated form between acetoxy groups and calcium hydroxide, which is considered to be present in a small amount on the surface of calcium carbonate, is also conceivable.

The calcium carbonate used in the present invention does not need to be particularly restricted, and various types of commercially available heavy and sedimentable calcium carbonates can be used. The use of calcium carbonate as a filler is widely practiced and has no specialty,
However, the only filler that can be used in combination with a resin composition whose pH is adjusted to 8 or higher without impairing the physical properties is a mixture of a vinyl acetate polymer emulsion containing modified polyvinyl alcohol as a protective colloid and an unsaturated (meth) acrylate. The fact is not known.

The amount of calcium carbonate used is 1 to 100 parts by weight of the solid content of the vinyl acetate polymer emulsion.
It is at least 300 parts by weight, more preferably at least 10 and at most 200 parts by weight. If the amount used is less than 1 part by weight, the meaning of use is poor, and adding more than 300 parts by weight does not help to improve the adhesive strength. As for the method of addition, the powder may be added to the emulsion as it is and stirred, or may be used as a slurry in which an appropriate dispersant is used in combination.

Even in the case of a resin composition using calcium carbonate in combination, it is necessary that the pH of the resin composition be 8 or more as described above. Adjustment of the pH is performed in the same manner as described above.

When the curable resin composition of the present invention is put into practical use as an adhesive, an organic or inorganic reinforcing material, fillers, coloring agents, modifying polymers and oligomers, etc. are used in combination as necessary. Of course you can.

[0033]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.

[Modified polyvinyl alcohol (AA-modified PV)
Synthesis of Vinyl Acetate Polymer Emulsion A Using A) as Protective Colloid] In a 2-liter separable flask equipped with a stirrer, reflux condenser, thermometer and dropping funnel, AA-PVA [trade name: Gosefimer Z-20]
0; acetoacetoxy group content of about 5 mol%, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.] and 400 g of 10% aqueous solution and 300 g of water
And heated to 70 ° C. 25 g of vinyl acetate, 10
1% aqueous solution of ammonium persulfate was added,
After 5 minutes, water was added to 5 g of 10% ammonium persulfate to make the total amount 30 g, and 475 g of vinyl acetate were simultaneously added dropwise over 4 hours. The reaction temperature at this time was 8
It controlled so that it might be 0-85 degreeC. After dropping, the mixture was aged at 85 ° C. for 1 hour, cooled to 30 ° C., and 20 g of dibutyl phthalate was added to obtain a polymer emulsion. The solid content of the vinyl acetate polymer emulsion A using the obtained AA-PVA as a protective colloid was 45.
5% and viscosity (30 ° C.) was 26,500 mPa · s.

[Synthesis of Vinyl Acetate Copolymer Emulsion B Using AA-PVA as a Protective Colloid] 2 equipped with a stirrer, reflux condenser, thermometer and dropping funnel
In a liter separable flask, 10 parts of AA-PVA [trade name: Gosefimer Z-200; acetoacetoxy group content: about 5 mol%, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.]
% Aqueous solution and 300 g of water were charged and heated to 70 ° C. 25 g of vinyl acetate was added, 1 g of a 10% aqueous solution of ammonium persulfate was added, and after initial polymerization was performed for 15 minutes, water was added to 5 g of 10% ammonium persulfate to make the total amount 30 g, 450 g of vinyl acetate and 25 g of acetoacetoxyethyl methacrylate were simultaneously added. It was dropped over time.
The reaction temperature at this time was controlled to be 80 to 85 ° C. After dropping, the mixture was aged at 85 ° C. for 1 hour, cooled to 30 ° C., and 20 g of dibutyl phthalate was added to obtain a copolymer emulsion. The resulting AA-P
The vinyl acetate copolymer emulsion B using VA as a protective colloid has a solid content of 45.2% and a viscosity (30 ° C.) of 3
It was 1,500 mPa · s.

[Synthesis of Vinyl Ester (A)] 1 equipped with an agitator, a reflux condenser, a thermometer, and a gas inlet tube.
In a liter separable flask, 380 g of a liquid epoxy resin of bisphenol A-glycidyl ether type having an epoxy equivalent of 187 as an epoxy resin and acrylic acid 14 were added.
When 4 g, 1.5 g of triphenylphosphine and 0.3 g of hydroquinone were charged and reacted at 120 to 125 ° C. for 3 hours in an air stream, the acid value became substantially 0. A syrupy vinyl ester (A) having a Hazen color number of 300 and a viscosity of about 1500 poise was obtained.

[Emulsification of Vinyl Ester (A)] In a 500 cc separable flask equipped with a stirrer, reflux condenser, thermometer and gas inlet tube, 60 g of vinyl ester (A), and trimethylolpropane as a reactive diluent. After charging 40 g of triacrylate and 30 g of 50% nonionic surfactant, stirring for 30 minutes, water 10
0 g was added dropwise over 20 minutes. The mixture was further stirred for 1 hour to obtain a vinyl ester (A) emulsion having a concentration of 50.1% and a viscosity of 5 poise.

[Synthesis of Unsaturated Urethane-Acrylate (A)] In a 1 liter separable flask equipped with a stirrer, a reflux condenser and a thermometer, 2-hydroxypropyl acrylate 2 containing 0.15 g of methylbenzoquinone was added.
After charging 60 g and 140 g of benzene and removing water by azeotropic distillation with benzene, 35 mol (%) of 2,6-tolylene diisocyanate, 6,4-tolylene diisocyanate 6
174 g of 5 mol (%) mixed diisocyanate and 0.4 g of dibutyltin dilaurate were added and reacted at 75 ° C. for 4 hours. As a result of infrared analysis, it was confirmed that free isocyanate groups had completely disappeared in the reaction system. Then trimethylolpropane triacrylate 1
70 g was added, and benzene was finally distilled off under reduced pressure of 300 to 400 Torr. A viscous unsaturated urethane-acrylate (A) viscous at room temperature was obtained as a pale yellow viscous liquid.

(Example 1) As a vinyl acetate polymer emulsion, a vinyl acetate polymer emulsion A and a vinyl acetate copolymer emulsion B were used, and a resin composition was prepared by blending each emulsion with the following composition. (Composition of Resin Composition) Vinyl acetate-based polymer emulsion 89.0 parts by weight Vinyl ester (A) emulsion 2.5 parts by weight The pH of this mixed system was adjusted to 9.4 with aqueous sodium hydroxide solution to obtain a resin composition. . Using this resin composition as an adhesive, a birch material was adhered in accordance with JIS K-6852 (compression shear adhesive strength test method of the adhesive), dried at room temperature for 3 days, and then repeatedly boiled (JAS I ) And hot and cold water immersion test (JAS II). JAS I class test: Boiling 4 hours, drying at 60 ° C. for 20 hours, boiling 4 hours, immersion in water for 10 minutes, measurement of compressive shear adhesive strength. JAS II class test: After 3 hours of immersion in warm water at 60 ° C., measurement of compressive shear adhesive strength of a sample immersed in 20 ° C. water for 10 minutes Table 1 shows the test results.

Comparative Example 1 An adhesive using emulsion A and an adhesive using emulsion B were prepared in the same manner as in Example 1 except that the pH of the resin composition was changed to 2.4. Produced. Example 1 using these adhesives
When a repeated boiling test (JASIs) was carried out in the same manner as in the above, the test pieces peeled off during boiling in both cases, and the compression shear adhesive strength could not be measured. (Comparative Example 2) A repeated boiling test was performed in the same manner as in Example 1 using only the vinyl acetate polymer emulsion A or the vinyl acetate copolymer emulsion B and an adhesive having a pH of 3.4. As a result, the test piece peeled off during boiling in both cases, and the measurement of the compressive shear peeling strength could not be performed.

[0041]

[Table 1]

Example 2 Using vinyl acetate copolymer emulsion B, a resin composition having the following composition was prepared. (Composition of Resin Composition) Vinyl acetate copolymer emulsion B 92 parts by weight Unsaturated urethane-acrylate (A) 3 parts by weight 15% aqueous solution of lithium hydroxide 1.5 parts by weight The pH of the resin composition was 9.9.

Using the above resin composition as an adhesive, the adhesive strength was measured in the same manner as in Example 1. The results were as follows. Normal strength 50 kg / cm ² or more (wood fracture) boiling repeated test 25.3kg / cm ² hot and cold water immersion test 58.8kg / cm ² (wood fracture)

Example 3 Using a vinyl acetate polymer emulsion A, a resin composition having the following composition was prepared. Vinyl acetate polymer emulsion A 85 parts by weight Vinyl ester (A) emulsion 2.5 parts by weight 15% aqueous solution of lithium hydroxide 1.5 parts by weight The pH of the resin composition was 9.8.

Using the above resin composition as an adhesive, the adhesive strength was measured in the same manner as in Example 1. Normal strength 50 kg / cm ² or more (wood fracture) Repeated boiling test 19.8 kg / cm ² hot and cold water immersion test 62.9 kg / cm ² (wood fracture)

Example 4 Using a vinyl acetate polymer emulsion A, a resin composition having the following composition was prepared. (Composition of resin composition) 85 parts by weight of vinyl acetate polymer emulsion A 2.5 parts by weight of vinyl ester (A) emulsion 50 parts by weight of calcium carbonate (manufactured by Bihoku Powder Chemical Co., Ltd.) 50 parts by weight 15% aqueous lithium hydroxide solution 1 0.3 parts by weight The pH of the resin composition was 9.8.

Using the above resin composition as an adhesive, the adhesive strength was measured in the same manner as in Example 1. The results were as follows. Normal strength 50 kg / cm ² or more (wood fracture) Repeated boiling test 28.7 kg / cm ² hot and cold water immersion test 69.3 kg / cm ² (wood fracture)

[0048]

The curable resin composition of the present invention, unlike conventional adhesives for wood such as phenolic resin, urea resin or melamine resin, is an adhesive which is gentle to the human body because it does not contain formaldehyde. In addition, water-based vinyl urethane adhesives that do not use formaldehyde use diisocyanate, and it is necessary to use a solvent if necessary, whereas water is used as a dispersion medium for the emulsion. It is an environmentally friendly adhesive. Despite such a resin composition, when used for bonding wood, it has a higher bonding strength than the strength of wood, has a small decrease in bonding strength even with hot water at a high temperature, has a high resistance to hot water, It is excellent in hot and cold water, and has extremely excellent performance as an adhesive for woody building materials for indoor and outdoor use, a woody adhesive for furniture, furniture and the like.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI theme coat ゛ (Reference) C08L 75/14 C08L 75/14 (72) Inventor Eiichiro Takiyama 4-12-4 Nishi-Kamakura, Kamakura 4F Term ( Reference) 4J002 AC113 BE022 BF021 BF031 CD203 CF273 CH053 CK033 CK043 CK053 DE237 EH076 FD143 FD146 FD312 GJ01 HA07 4J027 AB03 AB14 AB22 AE02 AE03 AE04 AG04 AG05 AG09 AG12 AG13 AG14 AG15 CA23 AG01 CA26 AG02 AG27 FA262 FA272 FA292 GA02 HA146 HA156 HA196 HA296 HC01 JA03 KA16 KA38 LA07 LA08 MA08 NA12

Claims (6)

[Claims] (1) A vinyl acetate polymer emulsion using a modified polyvinyl alcohol in which a part of a hydroxy group is acetoacetoxylated as a protective colloid; and (2) more than one (meth) polymer in one molecule. A curable resin composition in which a mixture comprising an unsaturated (meth) acrylate having an acryloyl group is adjusted to have a pH of 8 or more. 2. The curable resin composition according to claim 1, wherein the modified polyvinyl alcohol in which a part of the hydroxy group is acetoacetoxylated has an acetoacetoxylation ratio with respect to the hydroxy group of 3 to 10 mol%. 3. An α, β-unsaturated group in an unsaturated (meth) acrylate having more than one (meth) acryloyl group per molecule per 1 mol of acetoacetoxy group in a vinyl acetate polymer emulsion The curable resin composition according to claim 1, wherein the compound is blended in the range of 0.1 to 1 mol. 4. The curable resin composition according to claim 1, wherein the curable resin composition further contains calcium carbonate. 5. The curable resin according to claim 1, wherein the amount of the calcium carbonate used is 1 to 300 parts by weight based on 100 parts by weight of the solid content of the vinyl acetate polymer emulsion. Composition. 6. A wood adhesive comprising the curable resin composition according to any one of claims 1 to 5.