JPS6017396B2 - Formalin-based condensation resin adhesive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a modified formalin-based condensation resin adhesive.

More specifically, the present invention relates to a formalin-based condensed resin adhesive that contains a specific polyvinyl alcohol-based copolymer modified by copolymerization and has excellent storage stability, mixing stability, initial adhesion, washability, etc. . Conventionally, formalin-based condensation resin adhesives are obtained by condensing formaldehyde with one or more amino compounds such as urea, melamine, and benzoguanamine, and phenolic compounds such as phenol and resorcinol. When used as an initial adhesive, the initial adhesion is poor and even after cold compression, the plywood peels or shifts, resulting in defective plywood and reduced workability. . Conventionally, as a method for preventing such poor initial adhesion, it has been carried out to add ordinary terminally modified polyvinyl alcohol (hereinafter abbreviated as PVA) or carboxymethyl cellulose.

However, carboxymethylcellulose merely exhibits a thickening effect and lacks initial adhesion, and modification with unmodified ordinary PVA increases adhesion but has the drawback of gelling when left unused. There have also been proposals to use various modified PVA, such as crotonic acid copolymerized modified PVA, sulfonic acid copolymerized modified PVA, or copolymerized PVA with alkyl vinyl ether or acrylamide, but the stability of the reaction process and the stability over time have been proposed. Currently, there are advantages and disadvantages in terms of initial adhesion, etc., and it is not possible to obtain anything that is necessarily satisfactory.

Furthermore, even if a formalin-based integrated resin adhesive formulated in this manner is used, there is a drawback that the cleaning performance and the reusability of cleaning waste water are poor. In view of these circumstances, the inventors of the present invention have conducted extensive research on adhesive compositions mainly composed of formalin-based condensed resin liquid, and have found that they incorporate a specific PVA-based copolymer modified by English polymerization, which will be described later. The present inventors have discovered that a formalin-based condensed resin adhesive with excellent storage stability, initial adhesion, and washability can be obtained by this method, and have completed the present invention.

That is, the present invention deals with fatty acid pinylesters having a hydrocarbon group having 6 or more carbon atoms, alkyl pinylethers having a hydrocarbon group having 6 or more carbon atoms, and Q-olefins having a hydrocarbon group having 6 or more carbon atoms. At least one monomer selected from the group consisting of 'B-ethyleneically unsaturated carboxylic acid or its lower alkyl ester or acid anhydride, and (C) vinyl acetate ester as essential components. This is a formalin-based condensed resin adhesive blended with a PVA-based copolymer obtained by alkali saponification of a copolymer obtained by polymerization using a formaldehyde. As a component, a monomer having a large aliphatic hydrocarbon group with a carbon number of 6 or more is selected, and among these, typical fatty acid vinyl esters include lauric acid vinyl ester, stearic acid vinyl ester, 1, 1, 3・3-tetramethylacid vinyl ester, 2, 2, 4, 4-tetramethylvaleric acid vinylester, or an average carbon number of 10
When the carboxyl group is Q to the tertiary or quaternary carbon atom, such as a mixture of vinyl esters of saturated branched fatty acids,
Examples include branched fatty acid vinyl esters existing at the - position, and typical alkyl vinyl ethers include lauryl vinyl ether, stearyl vinyl ether, and furthermore, those with carbon atoms of 6 Examples of Q-olefins having the above hydrocarbon groups include dodecene-1,
Examples include octadecene-1.

On the other hand, typical examples of ethylenically unsaturated carboxylic acids or their lower alkyl esters or acid hydrates used as component [B} include acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, citraconic acid and Examples include lower alkyl esters thereof such as methyl and ethyl, and acid anhydrides. Among these, dicarboxylic acids such as itaconic acid, maleic acid, and citraconic acid, lower alkyl esters thereof, and acid anhydrides are preferred. Among these, maleic anhydride, maleic acid monomethyl ester and itaconic acid are preferred. Furthermore, the proportion of the W component in the copolymer composed of these copolymerized components varies depending on the number of carbon atoms, but is between 0.2 and 1.
0 mol%, preferably 0.8 to 7 mol%, and [B
'The ratio of ingredients varies depending on the blending ratio of the ingredients, but 0
．． 2-10.0 mol% preferably 0.5-7.0 mol%
A range of is desirable.

The above-mentioned PVA-based copolymer used in the present invention can be produced by known polymerization and saponification methods.

That is, ■, 'B' and 'C' components are added all at once or continuously, and 2.
Polymerization is carried out using a known radical polymerization catalyst such as 2'-azobisisobutyronitrile or penzoyl peroxide. The copolymer obtained by the polymerization reaction is dissolved in alcohol, if necessary, aqueous atarkol, and saponified using an alkali as molten soot. As the alcohol used in this case, lower alcohols such as methyl alcohol and ethyl alcohol are preferably used. These alcohols may contain a solvent such as acetone, o-methyl acetate, ethyl acetate, benzene, etc., as long as the amount is 4% by weight or less. It is appropriate for the PVA copolymer used in the present invention to be blended in an amount of 0.2 to 1% by weight based on the formalin condensation resin, and the effect of the present invention is significant at 0.2% by weight or less. However, if it is added in an amount of 1% by weight or more, the viscosity of the system becomes higher than necessary, which not only reduces workability but also becomes disadvantageous in terms of cost.

The condensation reaction is usually carried out by preparing an aqueous formalin solution, an amino compound or phenol, or a PVA polymer and reacting in the presence of an alkali or zero acid catalyst at a temperature of 60 to 100°C for 0.5 to 4 hours. In some cases, P
The VA-based copolymer may not be added initially, but may be added during or after the reaction is completed. In actual use of the formalin-based condensed resin adhesive of the present invention obtained as detailed above, thickeners, extenders, foaming agents, auxiliary adhesives, etc. may be used in combination. The present invention will be explained in more detail below with reference to Examples, but these Examples are not intended to limit the present invention in any way.

In the examples, "parts" and "%" are based on weight unless otherwise specified. Examples 1 to 6 37 in reaction vessel
% of formalin, 15 parts of urea, and (for each of the PVA-based copolymers having various copolymerization compositions shown in Table 1) 10.% of PVA-based copolymer. A $100 portion was charged and mixed, and then a small amount of aqueous ammonia was added to adjust the pH to 8.0.

The contents were heated to 90QO over 40 minutes under the fly Azusa,
After the reaction was continued for another 90 minutes at this temperature, a 20% aqueous sodium carbonate solution was added to adjust the pH to 8.5. 100 parts of the urea resin liquid obtained in this way was mixed with 2 parts of wheat flour, 17 parts of water, and 0.5 parts of ammonium chloride to prepare a glue. Plywood was manufactured under the following conditions: 1/2 x 2, cold pressure 10 k9/1 x 1, hot pressure 10 kg/120 qo x 3 minutes.

Table 1 shows the cleanability of the above adhesive and the adhesiveness of plywood manufactured using the adhesive. Comparative Examples 1 to 8 Modified PVA other than the PVA-based copolymer specified in the present invention, mixtures thereof, and modified PVA (Comparative Examples 1 to 7 in Table 1) and carboxymethylcellulose were used and other conditions were used. A formalin-based resin liquid was produced in the same manner as in the example, and a sizing agent was also prepared.

The results are also shown in Table 1. As is clear from Table 1, the stability, adhesion, and washability of the formalin-based resin adhesive modified with the modified PVA-based copolymer specified in the present invention are superior to those of other modified PVA or a mere mixture thereof. Moreover, it can be seen that it is significantly superior to those of unmodified PVA and the like.

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Claims (1)

[Scope of Claims] 1 (A) Fatty acid vinyl ester having a hydrocarbon group having 6 or more carbon atoms, alkyl vinyl ether having a hydrocarbon group having 6 or more carbon atoms, or having a hydrocarbon group having 6 or more carbon atoms At least one monomer selected from the group consisting of α-olefins, (B) at least one monomer selected from the group consisting of ethylenically unsaturated carboxylic acids or lower alkyl esters thereof, or acid anhydrides; ) A formalin-based condensed resin adhesive containing a modified polyvinyl alcohol-based polymer obtained by alkali saponification of a copolymer obtained by copolymerizing using three components of vinyl acetate as essential components. 2 Component (A) is a branched fatty acid vinyl ester in which the carboxyl group is present at the α-position relative to a tertiary or quaternary carbon atom, and component (B) is maleic anhydride, maleic acid, or a monomer of this acid. The formalin-based condensation resin adhesive according to claim 1, which is at least one selected from the group consisting of dimethyl ester, itaconic acid, and dimethyl ester.