JPS5879069A - Adhesive composition preventing discoloration - Google Patents

Abstract

PURPOSE:The titled adhesive composition, prepared by incorporating a reducing discoloration inhibitor with a polyvinyl acetate emulsion, capable of preventing the discoloration of an adherend and generating no formalin, having improved adhesive effect, and useful for a paulownia decorative laminated board. CONSTITUTION:A composition obtained by incorporating 100pts.wt. polyvinyl acetate emulsion with preferably 1-10pts.wt. reducing discoloration inhibitor, preferably sodium thiosulfate, sodium sulfite or ''Rongalit ''. EFFECT:Any complicated steps, e.g. controlling the moisture in sliced veneers of paulownia and changing the composition by the material or seasons, are not wholly required.

Description

[Detailed description of the invention] This product @Hiro1l! lII composition, paulownia decorative veneer, Tokoro■@
Adhesive for paulownia decorative boards that adheres the center board to the facing board and gives it a decorative effect.Regarding the universal fat-discoloring adhesive composition. A mixture of vinyl acetate-based emulsion soda, area resin, and wheat flour is often used.

However, when using Elia formalin resin,
It has poor stability over time, and there are problems with the generation of chemicals due to decomposition of the resin. Formalin generated from furniture components migrates and adheres to stored clothing, etc., and in severe cases, the amount of formalin generated by furniture components exceeds the amount regulated for clothing, etc., and in recent years furniture components For this reason, attempts have been made to incorporate formalin catcher agents such as potassium urea and melanin 7 in order to absorb the formalin generated. However, such formalin catcher agents If, for example, paulownia veneer is bonded to a paulownia wood veneer using adhesive, the amount of formalin generated will be reduced, but the white surface of 44 may develop a pink to red color.

On the other hand, there is a method of using adhesives that do not generate phorin, but when using these adhesives, such as polyvinyl acetate emulsion seals, the discoloration is severe at 41K. The degree of discoloration of ζ differs depending on the rainy season κ when 8IIjt is high and the material of the clothing. The red color change makes paulownia less beautiful and makes it useless as a decorative material.

As a method to prevent discoloration, various adhesives were mixed and the moisture content of the material was controlled], and a kappa drying device was installed to diffuse the moisture in the bonded materials after bonding. Although 410 methods that include a bleaching step have been proposed by Yang Gan, these existing methods have not yielded satisfactory results. We have continued our intensive research into the above-mentioned problems with the anti-discoloration adhesive composition, and as a result, the present invention has proven to be a good product. Preventing the discoloration of the material does not generate co-κ-hol▼97, and provides an anti-discoloration adhesive composition with excellent adhesion effect without requiring any special measures during work. This purpose is achieved by a discoloration-proof adhesive compound prepared by blending a reducing discoloration inhibitor with a polyvinyl acetate resin.

The polyvinyl acetate emulsion in the present invention is an aqueous dispersion of vinyl acetate as a production agent, and includes monomers copolymerizable with vinyl acetate, such as ethylene, acrylic acid, and acrylic acid. Esters, methacrylic esters, methacrylic esters, vinyl chloride, itaconic acid, crotonic acid, maleic acid, maleic esters, 2- and droxyethyl 7-acrylate, N-methylacrylic acid, N-methylolacrylic acid It is an aqueous dispersion of a copolymer with an etherified product, etc. of 4JilL.

In addition, examples of reducing discoloration inhibitors related to the present invention include sulfites such as sodium sulfite and sodium hyposulfite;
Examples include thiosulfate salts such as diarylated 4-sulfur, sodium thiosulfate▲, stannic chloride, and rongalite. The amount of these reducing discoloration inhibitors is 1 to 10 in the vinyl acetate emulsion.
It is preferable to add in an amount of 1 to 10 parts by weight per 0 parts by weight κ. If the amount of reducing discoloration inhibitor is less than 1 part by weight, i
The discoloration prevention effect of I4 is poor, and 10 parts by weight or more is used.
The stability of the emulsion was deteriorated, resulting in destruction of the emulsion, generation of coarse particles over time, saponification reaction of vinyl acetate, etc. I! K. This results in a decrease in adhesive strength. Among the above-mentioned reducing discoloration inhibitors, sodium thiosulfate, sodium sulfite, and Rongalite are particularly suitable, considering their miscibility with vinyl acetate-based adhesives and stability over time. These may be used alone or mixed as appropriate, or when manufactured as Arashi 10 ζ and used to glue the center plate of a rope, for example. ,Special consideration is given to ingenuity, but it is not necessary to provide adhesive K as is.It does not require any complicated construction costs such as controlling the moisture content of the sio veneer O, or making folds in the composition depending on the season of the material. ．． Furthermore, using the composition of the present invention 9,7 eveningν
It is also possible to use a mixture of a part of synthetic rubber emulsion such as Copolymer Emulgene, 88R, and MBR, and wheat flour, starch, defatted soybean flour, etc. as a bulking agent. It is also difficult to use clay, kaolin, talc wood powder, walnut powder, etc. for bulk filling. These are at most 2 units per 1 unit K.
It can be used within the range of 00 weight X.

It is also possible to add K-formin-based shrinkage resin to the adhesive composition of the present invention, but in order to minimize the generation of formalin, the amount should be reduced to 1 ton to 4 liters. It is preferable to add an agent. In this case, the amount is preferably at most 50% by weight based on the emulsion K.

Furthermore, it is also possible to add polyhydric alcohols such as ethylene glycol, diethylene glycol, and glycerin to the adhesive composition of the present invention during operation of open time and closed time.

The fixing composition according to #4K of the present invention does not cause discoloration of the adhered materials, has an excellent adhesion effect, and does not generate any stains. In particular, when the adhesive of this invention is used in the production of paulownia veneer decorative boards, its special characteristics are even more evident. That is, without causing the discoloration from pink to red, which degrades the cosmetic properties of paulownia wood, it is possible to produce decorative boards directly with improved cosmetic properties.

The present invention will be specifically explained with reference to the following examples. A predetermined amount of the additive shown in Table 1 K was added, and a paulownia veneer of α16mb with a moisture content of about 20X was glued to a 178 semi-odorless baseboard K, under the conditions K below. Seal the container and leave it for a while, and observe the discoloration.The results are shown below.Adhesive condition: Amount of cloth 1007/,/ Grease IIOC hot press 40 seconds Mine Japan Wood Processing Technology Association's standard 9 Desicator method K has been decided● (same below)
(manufactured by Ku2ite Co., Ltd.) Discoloration Judgment Criteria 2 0 No change, Δ pale pink, (same as mine) x Red area Resin also shows a discoloration K effect, but the amount of formalin generated is extremely high. Although formalin was generated in the example of the present invention, the amount of fading was the same as the amount of formalin generated in plywood in #1, and the amount of formalin generated was not as great as that in the adhesive #LA)a of the present invention.

This Comparative Example-1 38-07 was applied alone, and a reddish paulownia decorative board κ below was applied with an aqueous whitening agent solution of 20F/II/20F/II/20F/II/. Look at the changes in 9●The results are shown in Table 2.

From the results in the table above, the 4N center plate may have changed color.
I can't do it myself, and I can't stop it from becoming one color without gluing it.
8 Example-2 Yodozol gQ-15 (polyvinyl acetate manufactured by Kanebo NSC Co., Ltd.; Ruho Polymer Emulsion Chemical) 10
01l1κ Sodium thiosulfate - 50% aqueous solution as shown in the table below.
After addition, adhesion was performed in the same manner as in Example 1, and discoloration was observed in a polyethylene bag. The results are shown in #g3 Table K. It can be seen that the effect of stopping discoloration does not fade even if the amount is increased with small powder.

Yi Example-5 Kodozoru 118-07 54 parts, 40 parts of wheat flour, 4 parts of water
0 parts, and 25 parts of UA-104 (area 1 hole resin aqueous solution manufactured by Sumitomo Bakelite Co., Ltd.) to make an adhesive. A discoloration test was conducted on a paulownia decorative board using the same procedure as in Example 1. The results are shown in Table 4. From the table above, the amount of formalin produced in the adhesive is as follows: It can be seen that in contrast to K, which is suppressed but discoloration is observed, the product of the present invention effectively suppresses K discoloration, and furthermore, it is possible to control the amount of formalin generated.

Example-4 E Yodozol BQ-15 100 parts κ Sodium thiosulfate 25%
A 1:1 mixture of an aqueous solution and a 25% aqueous solution of sodium sulfite
After leaving it at 30°C for 3 months, the discoloration rate of paulownia decorative board was tested in the same manner as in Example-1. There was no noticeable difference between the adhesive and the one applied using the compounded adhesive, and it was also stable with no changes in the adhesive. 4 people on the book Kanebo Co., Ltd. 1 piece -476-

Claims (1)

[Claims] (1) A discoloration-resistant adhesive composition containing a polyvinyl acetate-based engineered discoloration inhibitor. (4 Scope of patent requests in which the reductive discoloration inhibitor is sodium theosulfate, sodium sulfite, or tetranitrate (1) J
An anti-discoloration composition listed in J ffi. 《3》 The amount of reducing discoloration inhibitor is polyacetate-based! The anti-discoloration adhesive composition according to claim (1), wherein the amount is 1 to 10 parts by weight per 10 parts by weight of the adhesive.