JPH01139666A - Bonding method - Google Patents

Abstract

PURPOSE:To perform bonding of cloths at high curing rate and high adhesive strength, by laminating a polyurethane adhesive with a cloth coated with an isocyanate curing catalyst. CONSTITUTION:Various kinds of cloth such as cotton, hemp, nylon, glass fiber, etc., is impregnated with (A) a cure accelerator such as N-methylmorpholine and dried. The cloth is further coated with (B) a polyurethane adhesive, the adherend surfaces are made to contact with each other and the laminate is e.g., pressed to promote the curing of the urethane adhesive and quickly attain high adhesive strength by the action of the curing catalyst without causing the flowing-off of the adhesive.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an adhesive method with excellent curing speed and adhesive strength. More specifically, it relates to a bonding method using a polyurethane adhesive.

Conventional polyurethane adhesives include moisture-curing component adhesives in which polyisocyanate urethane prepolymer is cured by moisture in the atmosphere, and moisture-curing component adhesives in which polyisocyanate urethane prepolymer is used as the main ingredient and active hydrogen compounds such as polyols are used as the curing agent. There are two-component adhesives that mix the two, and can be used on fibers, wood, plastics, rubber, metals,
Used for a wide range of adhesives such as mortar.

Polyurethane adhesives exhibit excellent adhesion to the various materials listed above, but their biggest drawback is that they have a slow curing speed and slow development of adhesive strength, so they may require long-term pressing or temporary fixing depending on the application. is necessary.

Addition of a catalyst is a common means of accelerating the curing rate. However, when a catalyst is added to a one-component urethane adhesive that has been made to sag using finely powdered silica or the like, the thixotropy of the adhesive decreases, causing it to run off and contaminating areas other than the adhesive surface. Furthermore, the addition of catalyst reduces the storage stability of one-component adhesives.

When a catalyst is added to a two-component urethane adhesive, the adhesive thickens and begins to harden immediately after the base agent and curing agent are mixed, shortening the pot life of the adhesive and causing dissatisfaction with workability. .

The present invention provides a bonding method using a urethane adhesive that has a fast curing speed and improves the above-mentioned drawbacks.

An object of the present invention is to provide an adhesive method that has a high curing speed by combining (11) a polyurethane adhesive and (2) a cloth coated with an isocyanate curing catalyst.

That is, in the present invention, a curing accelerating catalyst of polyisocyanate is attached to the fabric in advance by impregnating various types of fabric with a curing accelerating catalyst and then drying it in the air, or by spraying a catalyst solution onto the fabric, and then the fabric is coated with a curing accelerating catalyst. This cloth may be placed on the surface to be adhered and, if necessary, temporarily fixed with an adhesive or tough car.

Next, a polyurethane adhesive is applied onto this cloth, and then the surfaces to be adhered are pressed together. Another method is to apply urethane adhesive on both sides of the catalyst-attached cloth, then apply it to the surface to be adhered and press it.There is no need to worry about the adhesive running off, and the urethane adhesive acts as a catalyst. Since the curing was accelerated, rapid adhesive strength was obtained.

Examples of the fibers for the cloth used in the method of the present invention include natural fibers such as cotton, linen, and silk, chemical fibers such as nylon, polyester, and vinylon, and glass fibers and metal fibers. These fibers are used in sheet forms such as knits, woven fabrics, or non-woven fabrics. The weave and thickness of the cloth will vary depending on the object to be adhered, and a thin cloth is preferable for smooth wood surfaces, plastics, paper, and metal utensils, and for concrete,
For adherends with rough surfaces such as mortar, bricks, tiles, and rough wood, a slightly thicker and coarsely woven cloth is preferred. As the catalyst, a known catalyst that promotes the urethanization reaction or the reaction between isocyanate and water can be used. That is, as the amine catalyst, N-methylmorpholine, dimethylbenzylamine, triethylamine, triethylenediamine, 1,4
There are curing agent catalysts such as tertiary amine catalysts such as diaza 2°2.2 bicyclooctane, and amino alcohols such as triethanolamine. As a metal catalyst, for example, octyl N
Sn, Sn such as lead naphthenate, zinc octylate, K,
Examples include organic acid metal salts such as Na, FeXZn5Pb, and metal chelate compounds. These catalysts may be dissolved in an aqueous solution or an organic solvent, and a cloth may be impregnated with this catalyst solution and then squeezed and dried to adhere, or the catalyst solution may be applied to the cloth uniformly by spraying, etc. .

As a polyurethane adhesive, there is a one-component curing type consisting of a polyisocyanate urethane prepolymer having an isocyanate group at the molecular end, or a two-component curing type consisting of a polyisocyanate urethane prepolymer as the main component and an active hydrogen compound such as a polyol as a subcomponent. Type polyurethane resin adhesive is used. That is, examples of the polyisocyanate compounds used in the present invention include aromatic compounds such as 2.4-toluene diisocyanate, 2.61-toluene diisocyanate, diphenylmethane diisocyanate, polyphenylmethane polyisocyanate (polymeric MDI), xylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate. family, aliphatic,
Examples include alicyclic polyisocyanates and mixtures thereof.

Polyols used in polyisocyanate urethane prepolymers include polyoxyethylene polyols, polyoxypropylene polyols, ethylene oxide/propylene oxide copolymer polyols, polyether polyols such as polytetramethylene glycol; various polyester polyols; Low-molecular polyols such as lengelicol and trimethylolpropane may be used alone or as a mixture.

Curing agents used in two-component polyurethane adhesives include ethylene glycol, propylene glycol, neopentyl glycol, butylene gelicol, glycerin,
Low-molecular polyols such as trimethylolpropane; amino alcohols such as triethanolamine and quadrol; active hydrogen compounds such as polyethylene glycol, polypropylene glycol, and 3,3'-dichloro-4,4'-diaminodiphenylmethane. These curing agents can also be impregnated into the fabric in advance together with the catalyst, depending on the case.

The polyurethane adhesive of the present invention may contain additives such as inert solvents, plasticizers, fillers, pigments, thickeners, searchability agents, and stabilizers, as required.

Examples of inert solvents include ethyl acetate, butyl acetate, and cellosolve acetate.1. Methyl ethyl ketone, toluene, xylene,
Alternatively, solvents without active hydrogen such as petroleum hydrocarbons are used. Examples of the plasticizer include dioctyl phthalate, dibutyl phthalate, butylbenzyl phthalate, and tricresyl phosphate.

Fillers include dry calcium carbonate, talc, clay, and carbon. Detectability-imparting agents include colloidal silica, aliphatic amide, and surface-treated calcium carbonate. In addition, it is also possible to add petroleum resins, rosin derivatives, etc. to enhance the thickening effect and adhesive effect. Furthermore, stabilizers such as antioxidants, pigments, and dehydrating agents can also be added.

Regarding the adhesion method using the polyurethane adhesive, for example, the catalyst-adhered cloth is attached or temporarily fixed to one adhesive surface of the object to be adhered with a small amount of adhesive or tacker, if necessary, and then After applying the polyurethane adhesive to the surface with a spatula, trowel, brush, spray, etc., the surfaces to be bonded may be pressed together (or, after applying the polyurethane adhesive to the catalyst-coated cloth and before curing, apply the polyurethane adhesive to the surface to be bonded). It may also be pasted and crimped.

In either case, it is necessary to strongly press the double-wave bonded body so that the polyurethane resin sufficiently contacts and wets the surface to be bonded. The object to be adhered is temporarily fixed or pressed for a certain period of time, and when the urethane resin hardens and the adhesive shear strength reaches 20 kgf/- or more, the pressing can be stopped and the object can be firmly adhered even if left as it is.

By using the method of the present invention, not only continuous bonding is possible, but also it is easy to apply a certain amount of adhesive per unit area of the object to be bonded, and there is no possibility that the adhesive will rub off and contaminate surfaces other than the surface to be bonded. It can be prevented.

Next, the present invention will be explained by examples.

Synthesis Example 1> While flowing nitrogen gas into a reactor equipped with a reflux condenser, a stirrer, and a nitrogen gas inlet, 64 parts of ethyl acetate and 64 parts of toluene were added.
Part, Polymeric MDI (M made by Nippon Polyurethane Co., Ltd.)
Add 250 parts of R-200) and 150 parts of polyoxypropylene glycol with an average molecular weight of 12,000 and mix at 80-85°C.
The mixture was reacted for 3 hours to obtain a dark brown viscous solution of polyisocyanate urethane prepolymer with an isocyanate content of 13.4%.

Next, 100 parts of the polyisocyanate urethane polymer solution obtained above and 82 parts of dried calcium carbonate were added.
1 part and 8 parts of colloidal silica were placed in a kneader, thoroughly kneaded while flowing nitrogen gas, and defoamed under reduced pressure to obtain a brown paste-like polyurethane composition.

<Examples 1 to 7> Gauze or glass cloth [Nittobo Co., Ltd. KCIOI
OB 104EV2) After being impregnated with the catalyst shown in Table 1 or a solution of a catalyst and a curing agent, it is pulled up and heated to 5-1 in air.
After air drying for 0 minutes, place the lauan square on one side, apply the polyurethane composition obtained in Synthesis Example 1 on it in an amount of about 0.1 g/-, overlap the other lauan square, press-bond, and shear tension. An adhesion test specimen was prepared.

The clamping force was approximately 11 gf/cd. After gluing, 30 minutes, 1
After standing for 2 hours, 5 hours and 24 hours, a shear tensile bond strength test was performed. The results are shown in Table-2.

Comparative Example 1> Example 1 without using a woven fabric impregnated with a catalyst or curing agent.
Table 2 shows the results of tests similar to those in 7.

Table-1 1) The numerical values of the catalyst solution in Table 1 represent parts by weight.

2) Gauze was used as the woven fabric in Example No. 7, and glass cloth was used in the others.

Table 2 1) The state of failure of the adhesive surface after 24 hours was all material failure of the lauan material.

<Example 8> In place of Synthesis Example 1, 25 parts of MR-200 was used as the main ingredient, and polyoxypropylene glycol 15 with an average molecular weight of 1000 was used.
A mixture of 15 parts of calcium carbonate and 15 parts of calcium carbonate is used as a hardening agent, a mixture of the main agent and a hardening agent is used as a two-component polyurethane adhesive, and a catalyst solution with the composition shown in Table 2 is used to impregnate glass cloth. The adhesion test was conducted in the same manner as in Examples 1 to 7 except that the adhesive was used. Table the results.
Shown in 3.

<Comparative Example 2> Table 3 shows the results of the same test as in Example 8 without using the glass cloth impregnated with the catalyst.

Table 3 1) Regarding the shear tensile adhesive strength after 24 hours, the state of failure was material failure of lauan in Example 8, and cohesive failure of adhesive in Comparative Example 2.

Claims (1)

[Claims] An adhesive method that has a high curing speed by combining (1) a polyurethane adhesive and (2) a cloth coated with an isocyanate curing catalyst.