JPS58189278A - Preparation of adhesive - Google Patents

Abstract

PURPOSE:To prepare an adhesive which has sufficient bonding strength even in a short time of pressing under heat, by adding a non-emulsifying isocyanate group-containing compd. to a water-based adhesive, accompanied or followed by strong agitation to form fine particles of the additive. CONSTITUTION:The titled adhesive is prepared by adding a non-emulsifying isocyanate group-containing compd. to a water-based adhesive (e.g. aqueous solution or emulsion type adhesive made from urea resin, etc.), accompanied or followed by strong agitation by means of a special mixer such as a high-speed rotating high shearing mixer/disperser or a colloid mill to crush the additive into fine particles of the size of 10mu or smaller, pref. 3mu or smaller. Particle board, plywood, etc. made with the adhesive have excellent resistance to water and weathering.

Description

DETAILED DESCRIPTION OF THE INVENTION In recent years, attempts have been made to bond wood using compounds containing incyanate groups, particularly methylene-crosslinked polyphenyl polyisocyanates (including diphenylmethane diisocyanate).

The adhesion mechanism of incyanate compounds is based on the fact that incyanate groups form frethane bonds with the hydroxyl groups of cellulose and also react with water to produce voluria. When used, it exhibits very excellent properties. However, this incyanate group-containing compound is very expensive compared to other wood adhesives, and the resulting products have not been commercially available.

As a method for solving the above-mentioned drawbacks, the present inventor first invented a method of adding a non-emulsifying incyanate group-containing compound to a water-based adhesive, but as a result of further research, it was found that This invention was completed based on the knowledge that the performance of the adhesive can be further improved by adding a non-emulsifying isocyanate group-containing compound to the adhesive, or by stirring strongly after the addition.

That is, in the present invention, while or after adding a non-emulsifying type incyane-1 group-containing compound to a water-based adhesive, strong stirring is performed to form the non-emulsifying type incyanate group-containing compound into fine particles. The present invention relates to a method for producing an adhesive, characterized in that:

In this invention, the compound containing an incyanate group includes a polymer having a low degree of polymerization and containing an incyanate group. A compound containing a non-emulsifying isocyanate group is a compound containing a non-emulsifying isocyanate group without using a surfactant or the like. Furthermore, the water-based adhesive refers to water-soluble or emulsion type adhesives such as urea resin, phenol resin, melamine resin, urea-melamine resin, and guanamine resin. The reason for using a compound containing a non-emulsifying isocyanate group is that if it is an emulsifying type compound, the surfactant used during emulsification may have a negative effect on the physical properties of the wood product, and it is also costly. This is because there is no need for an emulsification process, making it cheaper.

What is important in this invention is to vigorously stir the non-emulsifying incyanate group-containing compound while or after adding it to the aqueous adhesive. This strong stirring does not refer to stirring using a normal stirrer, but includes a high-speed four-turn strong shear type stirring disperser, a colloid mill, a pressure nozzle type emulsifier, an ultrasonic emulsifier, a mechanical vibration stirrer, a static This refers to stirring using a special stirrer such as a stirrer that uses an electric field, and these stirrs can produce the above-mentioned non-emulsifying isocyanate group-containing compound to a degree that cannot be obtained or is extremely difficult to obtain using a normal stirrer. It is to make it into fine particles. The particle size of the fine particles is preferably 10 microns or less, more preferably 10 microns or less.

If this particle size is made small, even if the same adhesive is used,
It has the effect of shortening the heat-pressing time and being able to bond wood materials with high moisture content. It is not clear why these effects occur, but the reason is that a large amount of finely divided non-emulsifying isocyanate group-containing compounds are attached to the adhesive surface of the wood material, and that there is a slight increase in the amount of ink on the surface of finely divided compounds. This is thought to be due to a reaction of cyanate groups. A slight reaction seems to occur on the surface of this compound, for example, when a non-emulsifying type of incyanate group-containing compound is added to water-soluble urea and the adhesive is stirred with an ordinary stirrer. This is because while the pot life of the adhesive is nearly one week, the usage time of the adhesive produced by this invention is as short as 6 days. Since one day is sufficient, there is no problem in the work process even if the pot life is reduced from one week to six days.

In this invention, when adding a compound containing a non-emulsifying type of Inn-Ane-1 to a water-based adhesive, it is necessary to consider whether to add all of the above compounds alone or to take into consideration workability, physical properties of wood products, etc. Although it is best if a solvent is added, it is also possible to add a solvent or the like as appropriate.

Since this invention is configured as described above, the effects listed below are produced.

(2) Particle boards or plywood with sufficient adhesion performance can be produced even if the chip moisture content or veneer moisture content is higher than conventional ones, and even if the time for curing and hot pressing is short.

■ Compared to conventional water-based adhesives containing emulsified compounds containing incyanate groups, the adhesive can be used for a longer period of time and has excellent workability.

■ Particleboard or plywood using the adhesive produced by this invention is water resistant.

Excellent weather resistance.

[Example 1] MDI polyisocyanate (Millione-1-MR300 manufactured by Nippon Polyurethane Co., Ltd.) was added to 100 parts by weight of water-soluble urea resin (solid content 50%) at a rate of 0.5% in terms of solid content. +0.20. 1 part by weight of 0.01% by weight was added to each, and the mixture was stirred and mixed at room temperature for 5 minutes at 10,000 rpm using a homo mixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) to obtain five types of desired adhesives. The particle size of the incyanate group-containing compound in the adhesive thus produced was mostly 1 to 6 microns.

[Example 2] A desired adhesive was obtained in the same manner as in Example 1 except that a water-soluble phenol resin (solid content 50%) was used in place of the water-soluble urea resin of Example 1.

[Example]

A desired adhesive was obtained in the same manner as in Example 1, except that a homogenizer was used in place of the homomixer in Example 1.

The particle size of the compound containing incyanate groups in the adhesive thus produced was less than 1 micron.

[Comparative Example 1] 57 A 5-Yuzu adhesive was obtained in the same manner as in Example 1, except that a normal stirrer was used instead of the homomixer and stirred for 5 minutes. The particle size of the compound containing incyane 1 group in the adhesive thus produced was 10
It was almost over a micron, and the thickest ones were over 40 microns.

Example 1 In order to compare the five types of adhesives manufactured in Comparative Example 1, particle boards with a thickness of 20 mm were manufactured under the conditions described above, and the peel strength of the inner layer was measured. At the same time, the hot pressing time was measured within a range that would not cause adhesive failure. The results are shown in Tables 1 and 2, respectively.

Chip moisture content 10% Heat pressure time 6 minutes Heat pressure temperature 150°C Heat pressure 25 Adhesive addition rate Chip for surface layer 12% Chip for inner layer 7% Table 2 Addition rate (parts by weight) → Flatness] 9 1st From the table and Table 2, it is understood that adhesives manufactured by vigorous stirring have better peel strength and require less heat-pressing time than adhesives produced by normal stirring. can.

Patent Applicant: Hyijin Sangyo Co., Ltd. Procedural Amendment January 2, 1980 Director General of the Patent Office Shima 1) Haruki Tono Dano~ ::″,′ ] Case description ゛” 1982 Patent Application No. 7777J'o No. 2, Name of the invention Method for manufacturing adhesives 3 Person making the amendment (Relationship with II Patent Applicant's location Bi 559 Irisaka city Sumino t1-ku 1
2 Hayashi Minami 2 ■-110 No. 6 ozu T E L Osaka 06 (
681) No. 1111 (Contact Patent Division) 5. Engraving of the specification subject to amendment (no change in content) 6. Contents of amendment

Claims (1)

[Claims] An adhesive characterized in that the compound containing a non-emulsifying type incyanate group is agitated vigorously while or after the addition of the compound containing a non-emulsifying type incyanate group to a water-based adhesive to form fine particles. Production method.