JPS6016478B2 - Adhesive for wood materials - Google Patents

Description

[Detailed description of the invention] The present invention relates to an adhesive composition for wood materials.

More specifically, the present invention relates to an adhesive suitable for producing wood, wood materials, and composite wood materials such as plywood, wood-metal plywood, overlay plywood, laminated board, particle board, and wood-wool cement board. As adhesives for wood materials, precondensation resins such as urea-formaldehyde, melamine-formaldehyde, and phenol-formaldehyde have been widely used singly or in the form of co-condensates. Such thermosetting synthetic resin adhesives have high adhesive strength and excellent water resistance, and are therefore used in large quantities mainly in fields that require strength and water resistance. However, these thermosetting resin adhesives inherently have the following drawbacks. First, all of these adhesives are thermosetting, and only exhibit their effectiveness when a large amount of heat is applied to them to heat cure them.

This heating process requires equipment, time, and manpower, and is a major obstacle when using this type of adhesive. For example, manufacturing plywood requires huge hot press equipment, and when using thick boards, the disadvantage is that it takes a very long time due to the poor heat conductivity of wood. . Second, these thermosetting adhesives generally require an acid catalyst such as ammonium chloride, and the parenthesis reaction proceeds even at room temperature, which not only has the disadvantage of having to be formulated at each site where the adhesive is used. Since the adhesive composition once produced must be used in one production, there is a large loss of the remaining adhesive composition used.

Thirdly, unreacted formaldehyde remains for a long period of time even after the final product is made, and this odor poses a major environmental and social problem.

Other disadvantages include insufficient initial adhesive strength and difficulty in bonding if the wood to be bonded has a high moisture content.
For this reason, it has drawbacks such as requiring large equipment to dry the veneer. On the other hand, when making plywood using an adhesive mainly made of synthetic latex such as styrene-butadiene copolymer latex, it has adhesive strength even with cold pressing (pressure bonding at room temperature), but on the other hand, it has poor water resistance. There is a disadvantage that it is inferior. Therefore, various studies have been made to improve the water resistance of carboxylated synthetic latex by using metal compounds such as Acid-Inimono or epoxy compounds, but these methods require a heat-pressing operation after lining. However, the drawbacks such as poor workability have not yet been resolved. Therefore, the present inventors have conducted intensive research to solve the above-mentioned drawbacks of ordinary wood adhesives, and have found that by combining polyamine or imine with carboxylated synthetic latex, adhesives can be bonded at room temperature. We have discovered that it is possible to obtain an adhesive composition that has sufficient water resistance without heating the adhesive part, and that can withstand long-term storage without deterioration.
We have arrived at the present invention.

That is, the present invention is an adhesive for wood materials characterized by containing a carboxylated synthetic latex and a polyamine.

The carboxylated synthetic latex used in the present invention is not particularly limited, but it is an aqueous dispersion of a polymer containing a carboxyl group or a carboxylic acid salt. Specifically, at least one selected from styrene, styrene derivatives, butadiene, acrylonitrile, chloroprene, 1,3-hexadiene, isoprene, isobutene, acrylic ester, methacrylic ester, vinyl acetate, ethylene, pinyl chloride, vinylidene chloride, etc. A dispersion of a copolymer of a monomer and an unsaturated monomer having a carboxyl group can be used. Examples of unsaturated monomers having a carboxyl group include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, itaconic acid half ester, fumaric acid, fumaric acid half ester, maleic acid, maleic acid half ester, etc. 0.1-2% by weight can be used. Further, as the polyamine, for example, ethylenediamine, propylene diamine, triethylenetetramine, hexamethylene diamine, tetraethylenebentamine, etc. can be used.

Among these, ethylenediamine, hexamethylene diamine, etc. are preferred as they provide excellent water resistance and adhesive properties.

The mixing ratio of the latex and the amine is 2 to 5 parts by weight, preferably 5 to 1 part by weight, per 100 parts by weight of the solid content of the latex.

As the adhesive composition of the present invention, it is possible to use a synthetic latex and one or more of the above-mentioned amines in an appropriate combination, and generally, in addition to the synthetic latex and amine composition, clay, It is also possible to add inorganic or organic fillers such as calcium carbonate, aluminum hydroxide, wood flour, viscosity regulators, feed regulators, stabilizers, etc. as necessary.

Furthermore, depending on the purpose, it may be used in combination with casein, starch, natural rubber latex, urea-formaldehyde cocondensation resin, epoxy resin, etc. The adhesive composition of the present invention is stable over a long period of time with almost no change in viscosity, and has excellent adhesive strength without deterioration even after long-term storage.

In addition, sufficient adhesive strength and water resistance can be obtained simply by pressing at room temperature without heat-pressing. In particular, when bonding wood to wood, there are no negative effects such as alkaline oxidation, and sufficient adhesion and water resistance can be obtained just by pressing at room temperature. There is no need for heat and pressure bonding operations, and the plywood manufacturing process can be greatly simplified.

As mentioned above, the adhesive of the present invention is particularly suitable for manufacturing plywood, etc., but can also be used in a wide variety of adhesive fields such as metals, paper, fibers, plastics, etc.

In the following examples, parts and percentages are as follows, unless otherwise specified:
Depends on weight.

Example 1 1 part of calcium carbonate Super S (manufactured by Maruo Calcium) per 100 parts of carboxyl-modified styrene-butadiene copolymer latex JSR-06 rudder (manufactured by Japan Synthetic Rubber)
0 Ikari Kaku, Polyacrylic Acid Sodium Aron A-2 Mountain (manufactured by Toagosei Chemical Co., Ltd.) 1. An adhesive was prepared by adding 7.5 parts of ethylenediamine to the mixture.

Various adhesives were prepared in the same manner as above except that various amines were used instead of ethylenediamine. When ethylenediamine is used in these adhesives, the viscosity is 330 ps (measured with a BM paper density meter of 60 pm).
pH was 12.3. Using these adhesives with a roller, apply 20 Tano 900 coated 1.5-thickness lauan veneer (water content 7.5%) to fibers according to the Japanese Agricultural Standards (hereinafter referred to as JAS) for ordinary plywood. The three sheets were aligned so that their directions were perpendicular to each other and pressed together for 30 minutes at a pressure of 10k9' to produce a three-layer plywood board.

For comparison, Uria formaldehyde resin adhesive for Type 2 plywood based on JAS (Hounen Resin Glue VL-002)
Adhesive composition 1 was prepared by adding 4 parts of wheat flour and 1 part of ammonium chloride to 100 parts (manufactured by Hounen Oil Co., Ltd.), and the viscosity of composition 1 was 130 ps and the pH was 7.0.

Separately, instead of the urea formaldehyde resin of Example 1,
Melamine-Uria co-condensed resin adhesive Harunen Resin Glue M
Composition 2 was prepared in the same manner as in Example 1 using L-037 (manufactured by Hounen Oil Co., Ltd.).

Composition 2 had a viscosity of 170 ps and a pH of 6.5. For Compositions 1 and 2, plywood was prepared in the same manner as for the adhesive compositions, and evaluated according to the test method based on JAS. However, since Compositions 1 and 2 are usually used under hot pressure, the composition of the present invention was also left overnight after the cold pressure was released, and then heated under a heat eave for 3 minutes at 110°C 10k9/m. The produced plywood was evaluated using a test method based on JAS.

The results are shown in Table 1.

Table 1 Fracture rate; Wood fracture rate When the adhesive part of plywood is peeled off, the percentage of broken wood that is stuck to the adhesive surface.

- indicates adhesive strength of 1.0K or less Example 2 Table 2 shows the results of a plywood adhesive strength test conducted on adhesive compositions in the same manner as in Example 1, with varying amounts of ethylenediamine.

Table 2 Note) The amount of ethylenediamine added is in parts per 100 parts of latex. From this result, the adhesive composition of the present invention can be applied either by cold pressing or by applying hot pressing to the Uria melamine co-condensed resin adhesive for JASI type plywood. It has water resistance comparable to
Moreover, it can be seen that it has sufficient strength to pass the JAS standard adhesive force standard (7 kg/).

Compared to the urea formaldehyde resin adhesive which exhibits no water resistance at all by cold pressing alone, the advantages of the present invention are obvious. Note that the plywood produced in this example had a pH of
Despite the use of a fairly high adhesive of 12.3, no so-called alkali burn phenomenon was observed.

Claims (1)

[Claims] 1 Carboxylated synthetic latex as solid content 10
An adhesive for wood materials, characterized in that it contains 2 to 50 parts by weight of polyamine relative to 0 parts by weight.