JPS6121981B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a powder composition for bonding wood, which is made into an adhesive liquid by adding water during use. Conventionally well-known melamine resin adhesives have excellent adhesive properties and other advantages, but in liquid form they have the disadvantage of a relatively short storage stability period. Furthermore, since curing usually requires heating at 70° C. or higher, it has been difficult to perform so-called room temperature curing. Moreover, although curing accelerators are used, the curing function often does not always reach the desired goal, and the water resistance is also not sufficient. Furthermore, after adhesion, the liquid sometimes seeped onto the surface of the wood. This invention attempts to eliminate these drawbacks, and its purpose is to obtain an adhesive with excellent storage stability. The second purpose is to simplify handling during use. The third purpose is to obtain a hygienic product that does not affect the human body. Another purpose is to obtain a material with excellent curability and water resistance. Other objectives and benefits will be readily understood from the following description. One of the basic components of this invention is an alkylamine derivative of isobutylene-maleic anhydride copolymer (existing chemical substance No. Ministry of International Trade and Industry notification No. 571 official gazette classification (6) 778, hereinafter referred to as "semi-amide compound"). Powder of melamine methylol compound or its initial condensate obtained by reacting melamine and formaldehyde with 100 parts by weight of powder of
It is made by mixing 500 parts by weight, and is dissolved in an appropriate amount of water before use. Regarding another invention, the powder mixture of the methylol compound of melamine or its initial condensate is
Polyvinyl alcohol powder below mol% 10~500
It is prepared by mixing parts by weight, and is dissolved in an appropriate amount of water before use. The details of this invention will be explained below. The isobutylene-maleic anhydride copolymer is used in the form of a solution together with a thermosetting resin, but since it is in a liquid state, gelation progresses during storage, resulting in poor storage stability. In view of the above-mentioned points, the inventors of the present invention sought to obtain a powder composition with particularly excellent storage stability by preparing in advance a powdery composition with high water solubility. A methylol compound of melamine obtained by reacting melamine and formaldehyde or an initial condensate of trimethylolmelamine resin was mixed with a powder of a semi-amide compound of isobutylene-maleic anhydride copolymer, water was added, and the mixture was stirred and dissolved. It was easily dissolved to obtain an adhesive liquid, and when this adhesive liquid was used for bonding wood, a thermosetting reaction occurred upon heat treatment at 100°C to 120°C, and excellent results were obtained in both adhesive strength and water resistance. Furthermore, the adhesive solution obtained by adding ammonium sulfamate, ammonium nitrite, ammonium chloride, etc. as a curing accelerator to the above powder, and further adding water and dissolving it with stirring exhibits a curing reaction at room temperature of 20 to 30°C. When used as an adhesive, excellent results were obtained in both normal adhesive strength and water-resistant adhesive strength. In these reactions, the reaction between the acid anhydride group in the isobutylene-maleic anhydride copolymer molecule and the methylol group in the melamine resin molecule becomes three-dimensional due to heating or the intervention of an acidic component of a curing accelerator. Therefore, it is judged that excellent physical properties such as water resistance can be obtained. According to the present invention, melamine resin, which has conventionally been difficult to use at room temperature, undergoes an excellent curing reaction at room temperature and can now be used as a wood adhesive. Furthermore, partially saponified PVA of these powder compositions
(Gohsenol GH-17S manufactured by Nippon Gohsei Co., Ltd.,
It is presumed that the reaction becomes even more specific by using powder of #205S (manufactured by Kuraray Co., Ltd.) or wheat flour. In other words, what used to be a reaction between an acid anhydride group and a methylol group undergoes a unique reaction in which the hydroxyl group of partially saponified PVA reacts, and the hydroxyl group of starch flour reacts with the acid anhydride group and methylol group, respectively. The above reaction is shown by a chemical formula as follows. The above reaction mechanism can be fully utilized as a wood adhesive. In addition, partially saponified PVA has the effect of imparting flexibility to the cured product. Furthermore, the combination of the vinyl acetate homopolymer emulsion powder or the vinyl coprimer emulsion powder used in the present invention has the characteristic of stabilizing the wood adhesive strength of the emulsion adhesive and the flexibility of the cured product. This is effective in the present invention because it can take advantage of the characteristics that impart gender. Partial saponification
When using PVA in combination, a powder that is soluble in water at room temperature and has a degree of saponification of 90 mol % is a good idea, and the degree of polymerization is not particularly limited, but in general, a degree of 500 to 2,400 is suitable, and the amount added is not particularly limited. For combination use of vinyl acetate homopolymer and vinyl copolymer emulsion powder, use commercially available emulsion powder (Movinyl Powder manufactured by Hoechst Synthetic Co., Ltd.).
It is appropriate to use DM-200, M-1), but
There are no particular restrictions on the emulsion powder as long as it can be dissolved and dispersed in water. There is also no particular restriction on the amount added, but a mixture of isobutylene-maleic anhydride copolymer semi-amide compound powder and melamine resin powder, or isobutylene-maleic anhydride copolymer semi-amide compound powder, melamine resin powder and partially saponified PVA 20 to 100 parts by weight of the powder mixture
100 parts by weight is judged to be appropriate. Melamine resin contains melamine and formaldehyde.
It is called a methylolated product or an initial condensation product of melamine, which is made into powder by a method such as spray drying after heating reaction at pH 7 or higher, and in the present invention, Nicaresin, which is a commercially available trimethylolmelamine, is used.
S305 and S260 are used, but a so-called melamine co-condensate, in which a part of melamine is substituted with urea, benzoguanamine, phenol, resolmin, etc., is used, and formaldehyde other than general formalin, such as paraformaldehyde or methyl formalin, is used. Components that act as formaldehyde may also be used. If a filler such as wood flour, kaolin clay, or wheat flour is added to the composition of the present invention at the same time, it will be useful to prevent step-growth when water is added during use and to prevent moisture absorption during storage. constitute an invention. When the composition of the present invention is dissolved in water and used, these substances may be added or blended at will depending on the purpose of use. Examples and their adhesive strength tests are shown in the table below.

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

[Table] The details of the adhesion test are as follows. For adhesion of birch materials to each other For adhesion of lauan materials to each other Apply the amount of application (150 g/cm ² ) and the clamping force of 10 kg/cm according to the method shown in JISK6801 (urea resin wood adhesive) compressive shear adhesive strength. cm ² and compaction temperature condition is 20℃
When the temperature was 30°C to 30°C, it was pressed for one day, and when the temperature was 100°C to 120°C, it was pressed for 1 hour, further pressed at room temperature, and left to stand for 6 days before making a test piece. The normal adhesive strength was measured using the test piece prepared as described above. The water-resistant adhesive strength was measured by soaking the test piece prepared by the above method in room temperature water for 12 hours, taking it out, and measuring it while still wet. In the case of gluing veneer and plywood: Application amount of elm or birch veneer and plywood (lauan 3mm thick): 100 g/cm ² Clamping force: 10
Kg/cm ² Bonded at 100° C. to 120° C. for 90 seconds, left at room temperature for 3 days, and then subjected to immersion peeling test based on the Japanese Agricultural Standards for Special Plywood. The term "isoban #104, #110" refers to a commercially available trade name of a semi-amide compound of isobutylene-maleic anhydride copolymer. "Nica Resin S-260, S-
305" refers to the commercially available product name of melamine methylol compound or initial condensate powder. "Partially saponified PVA" is an abbreviation for polyvinyl alcohol powder with a degree of saponification of 90 mol%. Based on the results shown in Table 1, in Examples 1 to 5, melamine methylol compound or initial condensate powder was added to
It is clear that the adhesion strength is significantly improved by mixing ~300 parts by weight. Two months after mixing, the powder was placed in a two-layer kraft paper bag with a polyethylene inner bag, sealed, and left at room temperature, then dissolved in water and measured for adhesive strength, but there was no significant difference, indicating storage stability. It was done. From the results of Examples 6 to 10 in Table 2, it was determined that the addition of melamine resin powder and emulsion powder improved the adhesive strength even more than the isobutylene-maleic anhydride copolymer semi-amide compound powder alone. Ru. Two months after mixing, the powder was placed in a two-layer kraft paper bag lined with polyethylene, sealed, and left at room temperature, then dissolved in water in the same manner and the adhesive strength was measured, but there was no significant difference, indicating storage stability. From the results of Examples 11 to 14 in Table 3, melamine resin powder and partially saponified isobutylene-maleic anhydride copolymer semi-amide compound powder alone.
It was found that the adhesion strength was further improved by adding PVA, and the effect of using wheat flour in combination was also found at the same time. Two months after mixing, the powder was placed in a two-layer kraft paper bag lined with polyethylene, sealed, and left at room temperature, then dissolved in water in the same manner and the adhesive strength was measured, but there was no significant difference, indicating storage stability. According to the results of Examples 15 to 19 in Table 4, an emulsion was further added to a mixture of 10 to 300 parts by weight of melamine resin powder and 10 to 150 parts by weight of partially saponified PVA from the isobutylene-maleic anhydride copolymer semi-amide compound powder alone. It has been found that the adhesion strength is significantly improved by mixing the powder. Two months after mixing, the powder was placed in a two-layer kraft paper bag with a polyethylene inner bag, sealed, and left at room temperature.The adhesive strength was measured by dissolving the powder in water in the same manner, but there was no significant difference in storage stability. Admitted. According to the results of Examples 20 to 25 in Table 5, melamine resin powder, partially saponified
It has been found that good results can be obtained by improving adhesive strength by mixing PVA and emulsion powder, and by using a filler such as wood flour, kaolin clay, or wheat flour. Two months after mixing, the powder was placed in a two-layer kraft paper bag with a polyethylene inner bag, sealed, and left to stand at room temperature, then dissolved in water in the same manner and the adhesive strength was measured, but there was no significant difference, indicating storage stability. . According to the results of Examples 26 to 30 in Table 6, melamine resin powder and partially saponified isobutylene-maleic anhydride copolymer semi-amide compound powder alone
It has been found that by adding PVA, emulsion powder, and wheat flour either singly or in combination, the adhesive strength can be significantly improved even without the addition of a curing accelerator. From the results of Examples 31 to 49 in Tables 7 to 9, isobutylene-maleic anhydride copolymer semi-amidated powder alone was superior to melamine resin powder and partially saponified PVA.
By adding , it was possible to improve the adhesive strength. Even when up to 500 parts by weight of melamine was mixed, there was no effect and the results were good. Since this invention employs a medium alkylamine derivative of isobutylene-maleic anhydride copolymer as the adhesive composition, it is sufficient to simply add water during use. Conventional liquid adhesives of this type had the inconvenience of requiring heat treatment or troublesome pretreatment prior to use, but these inconveniences have been completely eliminated. Further, liquid adhesives may undergo chemical changes over time, but powder adhesives of the present invention have less of this risk and have excellent long-term storage stability. In this invention, 10 to 500 parts by weight of polyvinyl alcohol powder with a saponification degree of 90 mol% or less is further mixed, so that when used as an adhesive and cured, the adhesive does not harden excessively and retains its flexibility. Because of this, the adhesive will not crack or break. Therefore, it is possible to improve the adhesive strength.

Claims (1)

[Scope of Claims] 1. Powder of a methylol compound or initial condensate of melamine obtained by reacting 100 parts by weight of a powder of an alkylamine derivative of isobutylene-maleic anhydride copolymer with melamine and formaldehyde.
A powder composition for wood adhesion prepared by mixing 10 to 500 parts by weight. 2 10 to 500 parts by weight of a powder of a methylol compound or initial condensate of melamine obtained by reacting melamine and formaldehyde to 100 parts by weight of a powder of an alkylamine derivative of an isobutylene-maleic anhydride copolymer, and a degree of saponification of 90 moles. % or less of polyvinyl alcohol powder. 3. The powder composition for wood adhesive according to claim 1, which is prepared by adding an appropriate amount of wheat flour.