JPS6024826B2 - Adhesion method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating the surface of an adherend in order to achieve effective adhesion when using a cyanoacrylate adhesive.

The purpose is to accelerate the curing rate, improve adhesive strength, especially impact strength, and prevent whitening. General formula −
, (However, R is an alkyl group having 1 to 16 carbon atoms, an allyl group,
Q-cyanoacrylic acid ester (hereinafter abbreviated as cyanoacrylate) represented by a phenyl group has extremely high anionic polymerization activity, and can be rapidly reacted with so-called basic substances as well as with nucleophilic water and alcohol at room temperature. Polymerizes to give a strong polymer.

Utilizing this property, a uniform liquid adhesive containing this monomer as a main component and containing stabilizers, polymerization inhibitors, thickeners, diluents, plasticizers, colorants, etc., i.e., Q-cyanoacrylate adhesive BACKGROUND ART Agents (hereinafter abbreviated as cyano adhesives) are used as so-called instant adhesives to bond a wide range of objects such as metals, plastics, rubber, wood, and glass. Although cyano adhesives are widely used in this way, when adhering wood, plastics, etc., they are sensitive to the polarity of the adherends themselves and the substances contained in the adhesive materials that inhibit adhesion, such as acidic solvents. Delays in adhesion speed and decreases in adhesive strength, especially impact resistance, are observed due to the effects of mold release agents, fillers, etc.

In addition, a so-called whitening phenomenon may occur in which a white cloud appears around the bonded area bonded using a cyano adhesive. This phenomenon occurs when the monomer is removed before the curing of the cyanoacrylate.
It is understood that this is because the vapor from the adhesive evaporates and hardens around the bonded area, such as when an excessive amount of adhesive is applied and curing is delayed, when the adhesive is hot and humid, or when the adhesive is stored in an airtight container immediately after bonding. This is not only an aesthetic problem in that it contaminates the adherend, but also causes a deterioration in the electrical properties of the conductive material. In order to solve these drawbacks of cyano adhesives, aqueous alkali solutions such as caustic soda, caustic potash, soda carbonate, and ammonia, diethylamine, dimethyl/glatluidine, etc. have been conventionally used.
Measures have been taken to speed up the curing speed of cyanoacrylate by pre-treating the surface of the object to be treated with various amines such as dimethylaniline, ethanol/reamine, and phenylethanolamine, and then applying a cyano adhesive. .

However, with these known methods, even though the adhesion speed is improved, the adhesion strength decreases, the whitening prevention effect is not sufficient, and secondary drawbacks include bad odors and color stains other than whitening. did. The present inventors conducted research to improve the above-mentioned drawbacks of cyano adhesives, and after applying methylol urea and methylol melamine or their partial alkoxylates to the surface of adhesive materials, Not only does this eliminate the above-mentioned drawbacks of cyano-based adhesives, but also, unlike the alkalis and amines mentioned above, the effectiveness remains the same even when used for adhesion long after application. The present invention was completed based on the knowledge that the sustainability of the product is extremely excellent.

That is, the present invention requires that when adhering using a Q-cyanoacrylate adhesive, the surface of the adherend is treated with a compound selected from methylol urea and melamine or derivatives thereof, which may be partially alkoxylated. This is a unique bonding method.

Compounds used in the method of the invention include, for example, monomethylol urea, dimethylol urea, monomethylol monomethoxymethylol urea, dimethylol etherene urea, dimethylol dihydroxyethylene urea, monomethylol melamine, dimethylol melamine, trimethylol melamine. , hexamethylolmelamine, monomethylolmonomethoxymethylolmelamine, monomethyloltrimethoxymethylolmelamine, monomethylolbentamethoxymethylolmelamine, monomethylolmonoethoxymethylolmelamine, monomethyloltriethoxymethylolmelamine, dimethyloldimethoxymethylolmelamine, dimethyloltetrabutoxy Examples include monomers such as methylolmelamine, trimethylolmonobutoxymethylolmelamine, and tetramethylolpropoxymethylolmelamine, and polymers thereof, and these methylol compounds may be used alone or in combination.

In addition, caustic soda, soda carbonate, ammonia, diethylamine, which is a curing accelerator for conventionally known cyano adhesives,
Although it can be used in combination with an alkali or basic substance such as dimethyl/butralidine or ethanolamine, it is effective to use the above-mentioned tyrol compound as is) or a suitable solvent such as water, methanol, ethanol, propanol, butanol, acetone, It is used by dissolving or dispersing it in methyl acetate, methyl chloride, etc. These methylol compounds are applied to one or both of the adhesive materials that have been appropriately pretreated, such as wiping, degreasing, and sandpapering, and the cyano adhesive is applied as is or after spraying the solvent. When it is applied to one or both of the adhesives and brought into close contact, polymerization occurs remotely within a few seconds, completing the adhesive bond.

The resulting adhesive layer has a structure with excellent resistance to impact, peeling, and bending strength, and no whitening is observed. Color stains such as yellow, green, and brown that occur on the surfaces of adhesives pretreated with conventionally known alkalis and amines, especially plastics, light metals, and wood, are completely eliminated. Examples 1 to 6,
Comparative Example A case where 1 to 4 methylol compounds are treated with a 0.3% ethanol treatment liquid is used as an example, a case where a compound without a methylol group is treated with a 2% ethanol treatment liquid is used as a comparative example, and a cyano adhesive is treated with ethyl Add polymethyl methacrylate to Q-cyanoacrylate to obtain a viscosity of 300D
Tests were conducted on each of the following items using the S-rated product, and the results are shown in the table.

{1' A scale that indicates the degree of contamination of contaminating adherends, and is a measure of the degree of contamination of the adherend.
After wiping the surface of 25 x 100 x 2.7-2.8 (side) with a cloth soaked in each treatment solution and exposing it to direct sunlight for 5 days,
The state of surface contamination was observed.

■ Whitening property and adhesive strength Bakelite, steel, and lauan were selected as the adherend materials that are likely to cause whitening, and one adhesive surface of each test piece (25 x 100 x 2.0 (skin))
Apply each treatment solution to a 25x25), apply cyano adhesive to the other adhesive side, adhere with 1/2 inch overlap, compress with clip pressure, and then immediately place in a polyethylene bag. After curing at 20° C. for 3 days, the sample was taken out and the state of surface whitening was observed.

Thereafter, the tensile shear binding strength was measured at a tensile rate of 5 m/min. (k9/enemy)'31 Impact test 3-1 Steel test piece (1 x 1 x 3/8 inch, 1 x 13/
4 x 3'4 inches) was treated with a treatment solution, the other side was coated with a cyano adhesive and bonded, and then cured for 24 hours using an impact tester for adhesives (manufactured by Toyo Seiki Seisakusho). It was measured.

Environmental conditions are 20℃, 55-60% RH (k9-gu/earth)
3-2 Lay out the lauan 1x1x so that the end side becomes the adhesive side.
Cut into 3/8 inch and 13/4 x 3'4 inch 3-1
An adhesion test similar to that was conducted.

(1 block of k9/ground) ■ Distance hardening and efficacy persistence Merkaba test piece (25 x 100 x 3 (rib)) and steel test piece (2
After treating each of the 5 x 100 x 1.6 (fences) with a treatment solution, the same bonding as in '2) was performed every predetermined number of days.
After 1 minute of curing time, the tensile shearing adhesive strength was measured to evaluate distant curing properties and efficacy persistence.

The environmental conditions were 20 qo, 55-60% RH (k9/section).As is clear from the table, methylol urea and methylol melamine have excellent adhesive strength to various adherends, which was seen in the curing accelerators of the following. It can be seen that no such whitening phenomenon or color staining occurs, and the durability of the efficacy is outstanding. - Reiren Benawa Pass Mikami Ginjo Zarenge 3 N* IQ Senpaku Kosandokoro m XX A.

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Claims (1)

[Claims] 1 Adhesion characterized in that when adhering using an α-cyanoacrylate adhesive, the adherend is treated with a compound selected from methylol urea, which may be partially alkoxylated, melamine, or derivatives thereof. Method.