JP3252208B2 - Adhesive composition for veneer veneer and veneer veneer using said adhesive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive used for processing wood, in particular, a veneer veneer, and a veneer veneer obtained by using the adhesive.

[0002]

2. Description of the Related Art A veneer veneer (a veneer veneer) obtained by thinly slicing a tree called a precious wood such as a drill, a oak or the like on a wooden plate (base plate) such as plywood or particle board for the purpose of surface aesthetics. ) Is used for furniture, walls, flooring or ceiling panels. For veneer decorative products, the appearance of the surface has a significant effect on the commercial value,
Surface defects such as bleeding of the adhesive onto the veneer surface and drying of the veneer veneer (cracks) are fatal. In order to solve such a problem, a method in which paper is sandwiched between a veneer and a base plate and bonded to the amino resin has been used as an adhesive.
A method using a latex such as BR is proposed (JP-B-56-34196). However, the former method has the drawback that the work is complicated, the cost is high, and the adhesive strength is reduced.The latter method can prevent the exudation of the adhesive to some extent, but has the effect of suppressing the occurrence of cracks. Poor and practically problematic.

[0003]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems in the production of veneer veneer, and can prevent the exudation of the adhesive and the occurrence of cracks at the same time, and have good productivity. It is not intended to provide the composition.

[0004]

The present inventors SUMMARY OF THE INVENTION As a result of intensive studies when not overcome this problem, the amino resin, (except synthetic rubber latex) aqueous resin emulsion and Epo
The present inventors have found that an adhesive composition containing a xy compound has a remarkable effect on preventing the exudation of an adhesive and the occurrence of cracks in the production of veneer veneer and completed the present invention. That is, in the present invention, an aqueous resin emulsion (excluding synthetic rubber latex) is added to 100 parts by weight of an amino resin.
The same applies hereinafter) 100 to 2,000 parts by weight of an epoxy compound and 1 to 100 parts by weight of an epoxy compound.

[0005] Amino resins have conventionally been used for bonding veneers for the purpose of improving adhesive strength and water resistance. In this case, usually, flour is used as a bulking agent and ammonium chloride is used as a curing agent. are doing. In wheat flour, starch and protein contained as components serve to form a film and adjust viscosity, and contribute to the formation of a good adhesive layer when applied to a plywood plate as an adherend. However, after the subsequent hot-pressing step, the adhesive layer cannot follow the expansion and contraction of the base plate or veneer because the starch and protein harden the coating film of the adhesive layer, and as a result, cracks on the surface of the veneer plate It will happen frequently.

A melamine resin as an amino resin is effective in improving water resistance and adhesion of a veneer, and has the advantage of being rapidly cured by using ammonium chloride as a curing agent. Since the three-dimensional network is rigid but inflexible, it cannot follow the expansion and contraction of the base plate and the veneer plate, so that many cracks occur on the surface of the veneer plate.

On the other hand, there is a method of blending an aqueous resin emulsion in order to stabilize the viscosity and coating property of the adhesive coating liquid and to prevent bleeding of the coating liquid after bonding. Because it is crosslinked by amino resin,
The flexibility of the emulsion body is impaired, which also leads to multiple cracks on the veneer surface. To solve these problems, it is necessary to impart flexibility to the adhesive composition in order to prevent cracks.

In order to achieve this object, it is necessary that the cured product itself has a relatively gentle crosslinked structure. For this purpose, it is essential to use a substance that has a plastic effect on its own as well as making a relatively gentle cured product, instead of forming a very hard cured product like ammonium chloride as a cross-linking agent. Become. Therefore, the present inventors have used an epoxy compound for the core of the matrix, imparted flexibility to the cured product, and then imparted robustness to the adhesive layer by crosslinking the amino resin. The combination of an epoxy compound and an amino resin is optimal in terms of crosslinkability, flexibility of the cured product, and crack resistance. Also, since the amino resin used for veneer bonding is water-soluble, in terms of compatibility,
Particularly, use of an aqueous epoxy compound is preferred.

In the present invention, the amino resin is a condensate of a formaldehyde and an amino compound, and the degree of conversion of methylol group in all formaldehyde is 10 to 60% and the degree of conversion of dimethylene ether bond is 2 to 30%. It is characterized by being. The reason for limiting the range of the functional groups is that the degree of conversion of the methylol group is 10 to 60% and the degree of conversion of the dimethylene ether bond is 2 to 30%, because resins having various functional group compositions are synthesized to prepare the adhesive composition. By inductive selection of the results of making veneer veneer and stacking performance tests.

When an amino resin having a functional group composition in this range is used as a matrix constituting an adhesive composition for veneer veneer, the balance between the curing rate of the amino resin and the epoxy compound or the synthetic rubber latex is moderate. This is presumed to be due to the fact that the cured adhesive can form a flexible network. Each of these functional group compositions was measured using ¹³ C-NMR. Measurement conditions and
The analysis of the obtained signal is described in “Journal of P.
Polymer Science: Polymer C
hemistry Edition Vol. 173
205-3215 page (1979) ".

The aqueous resin emulsion used in the present invention is characterized in that the resin constituting the emulsion has an average particle size of 0.01 to 5 μm. If it is 0.01 or less, the viscosity after mixing with the amino-based resin and the epoxy compound greatly changes over time, and the water resistance is lowered. When it is 5μ or more, there is no problem in performance,
Precipitation is likely to occur, and the polymerization reaction time is prolonged, resulting in lower productivity.

The epoxy compound according to the present invention has an epoxy equivalent of 100 to 1000 (g / eq). If it is more than 1000, the crosslinking density is reduced and the adhesive strength is low. If it is less than 100, the crosslinking with the amino resin or the aqueous resin emulsion is too fast, and the pot life becomes short, making it difficult to use.

[0013] The present invention also relates to the bonding of a wooden base plate and a decorative veneer by mixing 100 to 2,000 parts by weight of a synthetic rubber latex and 5 to 100 parts by weight of an epoxy compound with 100 parts by weight of an amino resin. After bonding using the agent composition,
The present invention relates to a veneer veneer, wherein the surface of the veneer veneer is treated with a urethane sealer. Amino resin cross-linked with synthetic rubber has a hard gel structure,
When the epoxy compound is incorporated into the crosslinked structure at the same time as crosslinking, flexibility is imparted to the entire structure and a flexible adhesive layer is formed. In a form that does not impair this flexibility, the hydroxyl groups contained in the adhesive layer and the hydroxyl groups of the cellulose constituting the veneer and the urethane-based sealer react and combine to further increase the flexibility of the adhesive layer, thereby increasing the surface of the veneer and the base. In order to quickly disperse the stress generated on the board surface, even when the veneer veneer manufactured by the method of the present invention is used for floors and walls, the occurrence of cracks is extremely reduced, and the commercial value is significantly improved.

The amino resin used in the present invention may be a condensation resin of one or more amino compounds such as urea, melamine, guanamine and the like with formaldehyde, or these condensation resins may be phenols, resorcinols and the like. And modified resins partially modified with polyvinyl alcohol, furfuryl alcohol and the like.

The aqueous resin emulsion used in the present invention includes vinyl acetate resin emulsion, ethylene acetic acid copolymer resin emulsion, acrylic resin emulsion, acrylic / styrene copolymer resin emulsion, urethane resin emulsion and the like. It can be used in combination of more than one species.

The epoxy compound used in the present invention is generally a polyhydric alcohol glycidyl ether such as ethylene glycol glycidyl ether, propylene glycol diglycidyl ether, propylene glycol triglycidyl ether, sorbitol polyglycidyl ether, and trimethylolpropane polyglycidyl ether. There is an aqueous epoxy compound, a glycidyl ether of bisphenol A, epichlorohydrin or an epichlorohydrin derivative such as a polyamide polyamine epichlorohydrin resin, which can be used alone or in combination of two or more.

The urethane sealer used in the present invention may be any paint having a urethane bond (—OCONH—) in the coating film. (1) Polyester polyol,
A polyol component such as polyether polyol or acrylic polyol and hexadiamine diisocyanate (HD
I) a two-pack type urethane resin paint comprising isocyanate components such as xylene diisocyanate, toluene diisocyanate (TDI), a reaction product (prepolymer) of TDI and a polyhydric alcohol, and (2) an isocyanate group-containing prepolymer. Phenol or alcoholic OH
Block type polyurethane resin paint blocked with
(3) Moisture-curable polyurethane resin paint such as a compound in which toluene diisocyanate is pre-bonded with a di- or trihydric alcohol, (4) Oil-modified polyurethane resin paint in which toluene di-isocyanate is previously reacted with oil or oil-modified alkyd Etc. can be used alone or in combination of two or more.

Since the adhesive composition of the present invention is a self-crosslinking type, it is not particularly necessary to add a curing agent. However, in order to accelerate the curing, ammonium chloride, Inorganic salts such as ammonium sulfate, inorganic acids such as sulfuric acid and hydrochloric acid, and organic acids such as malic acid and oxalic acid can also be used in combination. Further, if necessary, a bulking agent commonly used for bonding wood, such as wheat flour, barley flour, coconut shell flour, corn gluten, starch, soybean meal, rapeseed meal, calcium carbonate, and clay may be used in combination. . The adhesive composition of the present invention may contain a synthetic rubber latex such as SBR and glycols such as polyethylene glycol and polypropylene glycol which have been conventionally used for preventing cracks.

[0019]

Embodiments of the present invention will be described below with reference to embodiments, but the gist of the present invention is not limited thereto.

Example 1 Ethylene / vinyl acetate copolymer resin emulsion (Co., Ltd.)
HWEN Corporation VWE-264 70% by weight solid content 55%, average particle size 0.6μ), melamine resin (MW-051 manufactured by HONEN CORPORATION)
Solid content 70%, degree of methylol group substitution 40%, degree of dimethylene ether bond conversion 25%) 25 parts by weight, barley flour 10 parts by weight, coconut shell powder 10 parts by weight, epoxy compound (K-1435, manufactured by Honen Corporation) Solids 97
% Epoxy equivalent: 125 g / eq) and mixed by stirring to prepare the adhesive composition of the present invention.

Example 2 60 parts by weight of vinyl acetate resin emulsion (VW-416 solid content 50%, average particle size 1.1 μm, manufactured by Honen Corporation), melamine resin (MW-900 solid content, manufactured by Honen Corporation) 70%, degree of methylol group substitution 30%, degree of conversion of dimethylene ether bond 13%) 30 parts by weight, flour 20 parts by weight, epoxy compound (K-133 manufactured by Honen Corporation)
0 solid content: 98% Epoxy equivalent: 155 g / eq) 5 parts by weight were mixed and stirred to prepare an adhesive composition of the present invention.

Example 3 Acrylic resin emulsion (AE-100 manufactured by Honen Corporation) having a solid content of 50% and an average particle diameter of 0.1%.
3μ) 70 parts by weight, urea melamine resin (manufactured by Honen Corporation, MW-052, solid content 70)
%, Degree of methylol group substitution 25%, degree of dimethylene ether bond conversion 7%) 25 parts by weight, barley flour 10 parts by weight, coconut shell powder 10 parts by weight, epoxy compound (K-1440 manufactured by Honen Corporation, solid content 97) % Epoxy equivalent, 230 g / eq), and mixed with stirring to prepare an adhesive composition of the present invention.

Comparative Example 1 Ethylene / vinyl acetate copolymer resin emulsion (trade name)
HONEN CORPORATION VW-416 Solid Content 5
0%, average particle size 1.1μ) 70 parts by weight, melamine resin (MW-053, manufactured by HONEN CORPORATION)
Solid content 70%, methylol group substitution degree 40%, dimethylene ether bond conversion degree 25%) 25 parts by weight, barley flour 10 parts by weight, coconut shell powder 10 parts by weight, ammonium chloride 0.25
Parts by weight were mixed and stirred to prepare an adhesive composition.

Comparative Example 2 Melamine resin (M manufactured by Honen Corporation)
W-045 Solid content 50%, Methylol group substitution degree 42
%, Degree of dimethylene ether bond conversion: 15%), 100 parts by weight of flour, 10 parts by weight of water, and 1 part by weight of ammonium chloride were mixed and stirred to prepare an adhesive composition.

Performance Evaluation Test 1 Using the adhesive compositions prepared in Examples and Comparative Examples,
Veneer veneer was prepared under the following conditions. Base plate 12mm lauan plywood, 30cm square moisture content 1
0% veneer 0.25 mm oak 30 cm square Application amount 10 g / 900 cm ² Heat pressure 110 ° C. 8 kg / cm ² 60 seconds Using the created veneer veneer, JAS class 2 immersion peel test and cold heat repetition B test were performed simultaneously. The state of seepage of the adhesive was also observed. Table 1 shows the results.

[0026]

[Table 1]

Performance Evaluation Test 2 After drying a 1 mm thick spruce sliced straight-grain veneer under reduced pressure of 10 mmHg, 100 parts by weight of an unsaturated polyester resin (alkyd styrene = 60: 40) and 10 parts by weight of methyl methacrylate polymer And a mixed resin solution containing 2 parts by weight of benzoyl peroxide was injected over a period of 8 hours to prepare a resin-injected veneer. Using this veneer as a veneer, using the adhesive compositions of Example 1 and Comparative Example 1,
A veneer veneer was prepared under the same conditions as in the performance evaluation test 1. Using the prepared veneer decorative plywood, a JAS class 2 immersion peel test and a cold repeated B test were performed, and at the same time, the state of exudation of the adhesive was also observed. Table 2 shows the results.

[0028]

[Table 2]

As shown in Tables 1 and 2, the decorative plywood of the adhesive composition of the present invention has no bleeding-out of the adhesive, the number of cracks is small in the performance evaluation test, and there is no practical problem at all. Was something.

Performance Evaluation Test 3 Using the adhesive compositions prepared in Example 1 and Comparative Example 1,
A urethane-based sealer was painted on the veneer decorative plywood prepared in the same manner as in the performance evaluation test 1 under the following conditions, and the performance was compared with that of the uncoated one. Coating conditions Paint Main agent: (Urethane Sealer HU-20 manufactured by Honen Corporation) Hardener: (K- manufactured by Honen Corporation)
1600) The base material / hardener / thinner were mixed and prepared at a weight ratio of 1000/25/300. Application amount 1.0g / 900
cm ²

The results of the JAS cold repetition B test are shown in Table 3.

[Table 3]

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-53-14741 (JP, A) JP-A-60-23467 (JP, A) JP-A-49-26348 (JP, A) 33174 (JP, A) JP-A-7-304004 (JP, A) JP-A-8-245937 (JP, A) JP-A-10-36803 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09J 201/00-201/10 C09J 161/18-161/34 C09J 163/00-163/10 B32B 7/12-7/14

Claims (5)

(57) [Claims] 1. An aqueous resin emulsion (excluding synthetic rubber latex) 100 to 2 parts by weight per 100 parts by weight of an amino resin.
An adhesive composition for veneer veneer, comprising 000 parts by weight and 1 to 100 parts by weight of an epoxy compound. 2. The amino resin is a cocondensate of a formaldehyde and an amino compound, and the degree of conversion of methylol group in all formaldehyde is 10 to 60% and the degree of conversion of dimethylene ether bond is 2 to 30%. The adhesive composition for veneer veneer according to claim 1, characterized in that: 3. An aqueous resin emulsion (synthetic rubber latex).
The average particle size of excluding box) is 0.01~5μ claim 1 or 2 veneer plywood adhesive composition according to. 4. An epoxy compound having an epoxy equivalent of 100
The adhesive composition for veneer veneer according to any one of claims 1 to 3, wherein the adhesive composition is from 1000 to 1000 (g / eq). 5. An aqueous resin emulsion (synthetic rubber rubber) is prepared by adding 100 parts by weight of an amino-based resin to a wood base plate and a decorative veneer.
Excluding tex) 100-2000 parts by weight, veneer plywood, characterized in that the bonding via the by blending an epoxy compound 1-100 parts by weight veneer plywood adhesive composition.