JP5349110B2 - Adhesive composition and method for producing veneer decorative material - Google Patents

Description

  The present invention relates to an adhesive composition that hardly causes gaps when bonding veneer plates without using a formaldehyde-containing resin.

  Conventionally, when adhering a veneer to a woody substrate such as plywood, a thermosetting resin produced by polycondensation of urea, melamine, and formaldehyde and a thermoplastic resin such as vinyl acetate resin are mixed. Adhesives have been used. However, due to the problem of so-called sick house syndrome, the building materials that emit formaldehyde more than a certain amount are restricted in the area of use. For example, building materials and adhesives used in these materials are required to be of a type that does not use formaldehyde. .

Therefore, modified vinyl acetate resins and those in which a specific curing agent is blended with vinyl acetate resins have been studied. On the other hand, when only such a thermoplastic resin is used, there is a problem that gaps are generated because the contraction of the projecting plate such as beech and maple and the projecting plate when the substrate is heat-pressed cannot be suppressed. .
JP 2006-28316 A

An object of the present invention is to provide a method for producing a veneer decorative material in which a gap is hardly generated when adhering veneers without using a formaldehyde-containing resin.

As a result of intensive studies by the present inventors , a veneer plate using an adhesive composition containing a vinyl acetate resin emulsion having an acetoacetyl group and having a minimum film-forming temperature of 10 ° C. or higher When the substrate was heated and pressed, it was found that a gap was hardly generated when the veneer was bonded.

  When the veneer and the base material are bonded using the adhesive composition of the present invention, the yield can be improved because a gap is hardly generated. Further, since it becomes possible to use a veneer of a material type that has been avoided in the past due to the problem of gaps, it is possible to perform veneer processing rich in design. Moreover, since no formaldehyde-containing resin is used, it is useful for residential use such as floors, furniture, and top boards.

  Hereinafter, the present invention will be described in detail. The vinyl acetate resin emulsion having an acetoacetyl group used in the present invention is obtained by emulsion polymerization of vinyl acetate and other monomers as required using a water-soluble polymer such as polyvinyl alcohol as a protective colloid. It is. The acetoacetyl group can be introduced by a method such as using polyvinyl alcohol having an acetoacetyl group in the emulsion polymerization, or copolymerizing monomers such as vinyl acetate and acetoacetoxyethyl methacrylate (AAEM).

  Further, if necessary, an emulsifier such as a surfactant may be used in the emulsion polymerization of the vinyl acetate resin emulsion, or a monomer such as ethylene, acrylic acid, acrylate ester, vinyl versatate may be used. . It is also possible to polymerize vinyl acetate alone or a monomer copolymerizable with vinyl acetate in the presence of an ethylene-vinyl acetate copolymer resin emulsion or an acrylic resin emulsion.

  In the adhesive composition of the present invention, known additives can be used in addition to the vinyl acetate resin emulsion having an acetoacetyl group. In order to improve the storage stability of the adhesive composition, it is preferable to add sodium bisulfite or ascorbic acid. In addition, a crosslinking agent such as an isocyanate compound, a thickener, a filler, a pH adjuster, a tackifier resin, a surfactant, a preservative, an antifoaming agent, and a rust preventive agent are included.

  The adhesive composition of the present invention needs to have a minimum film-forming temperature (MFT) of 10 ° C. or higher. If the MFT is less than 10 ° C., a gap is likely to occur when the protruding plate is bonded, which is not suitable. When only vinyl acetate is polymerized using polyvinyl alcohol as a protective colloid, the MFT of the resulting vinyl acetate resin emulsion is tens of degrees Celsius. MFT is lowered by copolymerizing acrylic acid ester during vinyl acetate polymerization, adding ethylene-vinyl acetate copolymer resin emulsion or acrylic resin emulsion, adding plasticizer, etc. If it is not used, it is necessary to adjust the type and amount.

  Since the adhesive composition of the present invention can be formed in an atmosphere of MFT or higher, it is not always necessary to heat and press in an atmosphere of MFT or higher. However, when adhering a protruding plate, moisture is removed during pressing. Therefore, it is preferable to heat-clamp. In addition, since it is necessary to use the adhesive composition of this invention in the atmosphere of at least 10 degreeC or more, it is difficult to use it in winter in a place without a heating installation.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example, this invention is not restrict | limited to an Example.

  Gosefimer Z-200 (trade name, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), an acetoacetyl group-containing polyvinyl alcohol, and B-05 (trade name, manufactured by Denki Kagaku Kogyo Co., Ltd.), an unmodified polyvinyl alcohol. 40 parts by weight was dispersed in 480 parts by weight of water and dissolved by stirring at 80 ° C. for 1 hour. Then, after adding 10 parts by weight of a 10% aqueous solution of aragonic acid and 10 parts by weight of a 1.4% aqueous solution of hydrogen peroxide, 390 parts by weight of vinyl acetate monomer, 20 parts by weight of acetoacetoxyethyl methacrylate, 40 parts by weight of a 1.4% aqueous solution is added dropwise over 3 hours to conduct emulsion polymerization, and further aged at 80 ° C. for 1 hour to give a vinyl acetate-based resin emulsion having an acetoacetyl group (AA Acetate 1, MFT12). C).

  Acetic acid having an acetoacetyl group is obtained by aging as in the production of the AA-modified vinyl acetate 1 and adding 20 parts by weight of phenyl glycol-H (trade name, manufactured by Nippon Emulsifier Co., Ltd.) as a plasticizer and cooling. A vinyl resin emulsion (AA-modified vinyl acetate 2, MFT 2 ° C.) was obtained.

  A-533E (trade name, manufactured by Aika Kogyo Co., Ltd.), which is a vinyl acetate resin emulsion having no acetoacetyl group, was used as vinyl acetate 3 (MFT 15 ° C.).

100 parts by weight of each vinyl acetate resin emulsion, 45 parts by weight of wheat flour (manufactured by Nisshin Flour Milling Co., Ltd., trade name Ginkgo) and 25 parts by weight of water were mixed to obtain each adhesive composition. 90 g / m ² of each adhesive composition was applied to a 2.5 mm thick JAS2 plywood, and a 0.3 mm thick beech veneer (dried) was bonded. This was pressed with a hot press set at 105 ° C. for 1 minute at 0.5 MPa, and cured at room temperature for 1 day to obtain a test specimen.

Adhesive performance Each specimen was subjected to a Type 2 immersion peel test based on JAS standards. Those that conformed were evaluated as ◯, and those that did not conform were evaluated as ×.
Interstices The surface of each specimen was observed to confirm the presence or absence of interstices on the veneer.

  Example 1 was excellent in adhesion performance and there was no generation of gaps. Comparative Example 1 was excellent in adhesion performance, but a gap was generated. Although the comparative example 2 did not generate | occur | produce the gap | interval, its adhesive performance was inferior.

Claims (1)

A veneer decorative material comprising a vinyl acetate resin emulsion having an acetoacetyl group, and a veneer and a substrate are heat-pressed using an adhesive composition having a minimum film-forming temperature of 10 ° C or higher . Production method.