JPH08259903A - Bonding technique - Google Patents

Abstract

PURPOSE: To obtain bonding in a short time with excellent initial adhesion, rapid development of hot holding characteristics and high reliability by applying a moisture-curing reactive hot-melt adhesive (RHM hereafter) to at least one of adherends, applying water containing a cure catalyst to an adherend and/or the surface of the adhesive, and pressing the adherends against each other while subjecting them to a slight vibration. CONSTITUTION: The slight vibration is a vibration of at least 1 cycle/sec. The RHM is a crystallization-solidifying type which is applied at 90-140 deg.C and has a solidification time of at least 2min. For example, the RHM is composed mainly of a prepolymer comprising an adduct or copolymer of, e.g. a polyester polyol that is solid at ordinary temperature with, e.g. a polyisocyanate compound. The water containing a cure catalyst is water having, for example, at least 1% triethylenediamine dissolved therein. Bonding is performed by heating and melting the RHM, applying the RHM melt to adherend(s), spraying water containing a cure catalyst thereon, and putting the adherends together to effect contact bonding while subjecting them to a slight vibration of 5-30 cycle/sec with an amplitude of 0.01-5mm. It is suitable to use, for example, a vibrator for the contact bonding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is directed to the bonding of components, such as
The present invention relates to a bonding method intended to be effectively used for a bonding method such as attaching a bracket (joint part) to a base material of an automobile door or a ceiling.

[0002]

2. Description of the Related Art Conventionally, brackets, which are attached to a base material such as a door and a ceiling of an automobile for the purpose of holding members such as an outer plate and an inner plate, are often made of steel and are physically attached to a wooden base material. It was attached by crimping. In recent years, there is a strong tendency for automobile materials to shift to resin materials for the purpose of weight reduction and cost reduction. When a moisture-curable reactive hot-melt adhesive (hereinafter abbreviated as R-HM) is used to attach resin parts, short-term adhesion is possible and heat resistance improves due to moisture curing reaction over time. The hot holding property of the member can be expected via the bracket.

[0003]

However, the resin parts have problems in that they have low moisture permeability and water absorption necessary for the reaction of R-HM, and have a long time for exhibiting the hot-holding property. . On the other hand, when a catalyst is added to R-HM for the purpose of enhancing the reactivity, there is a drawback that storage stability and melt stability of R-HM are impaired. The present invention has been made in view of such circumstances, and the bonding work is extremely simple, and a desired bonding strength can be obtained from the initial stage of bonding, and at the same time, the hot holding property is rapidly developed and is high. It is an object of the present invention to provide a bonding method that can obtain bonding reliability.

[0004]

[Means for Solving the Problems] The bonding method of the present invention is
It is characterized in that water containing HM and a curing catalyst is applied, and micro-vibration is applied to the adherend for pressure bonding.

That is, the inventors of the present invention have conducted extensive studies to overcome the above-mentioned drawbacks of the prior art. As a result, R-HM is applied to at least one of the adherends, and the adherend surface and / or The above-mentioned problems are solved by applying water containing a curing catalyst to the applied adhesive surface and then applying a slight vibration of 1 cycle / second or more to the adherend for pressure bonding, thereby solving the above-mentioned problems. It was found that adhesion excellent in hot holding property was obtained, and the present invention was completed.

The R-HM used in the present invention is a moisture-curing type reactive material which has a prepolymer having a functional group capable of reacting with water at the molecule end and is melted by heating during application. Refers to hot melt adhesive. For example, specifically, a prepolymer obtained by adding or copolymerizing a polyisocyanate compound or an alkoxy group-containing compound to one or more kinds of polyester polyols, polyether polyols, acrylic polyols, polybutadiene polyols, etc. which are solid at room temperature. The polymer is the main component. Such an R-HM has a temperature of 1000 to 5000 at 120 ° C.
It has a viscosity of 0 cP.

The water containing a curing catalyst refers to water or water in which a compound that accelerates the curing reaction is dissolved or dispersed, and the compound and the addition amount thereof are not particularly limited. For example, specifically, water obtained by dissolving 1% or more of tertiary amine-based triethylenediamine, N-methylmorpholine, hexamethylenetetramine, or the like can be used.

[0008]

In the bonding method of the present invention, R-HM is 90 to 14
It is heated and melted at 0 ° C., and applied on the adherend in a planar shape by using a die nozzle, a roll coater, or the like, or by spray application. The water containing the curing catalyst may be a known atomizer, or
It is preferable to apply the composition in a mist state by spraying, but it may be applied with a brush or the like. The surface to which the water containing the curing catalyst is applied may be either the adherend surface or the applied R-HM surface.
It is preferable to apply directly to the HM surface. Next, the adherends are overlapped with each other, and 1 cycle / second or more, preferably 5 to 30
Pressing is performed by applying a minute vibration having a cycle / second and an amplitude of 0.01 to 5 mm. The crimping to which slight vibration is applied can be easily performed by, for example, attaching a crimping plate to a commercially available vibrator and crimping using the same. Without this slight vibration, if you apply water containing the curing catalyst and simply perform static compression,
The effect of shortening the time to develop the hot holding property cannot be obtained, and
Initial adhesion is also reduced. That is, by applying a slight vibration and press-bonding, the water containing the applied curing catalyst becomes RH.
It is analyzed that it is diffused in the M layer, and this action accelerates the development of the hot holding property.

As the R-HM suitable for this action, it is desirable that the R-HM has an open time of 2 minutes or more and has a low viscosity during the micro-vibration pressure bonding. Such R-HM can be obtained by using a crystalline polyol and a non-crystalline polyol in combination to form a prepolymer by the above-mentioned method. Examples of commercially available R-HM used in the present invention include trade name "Hybon 4820" marketed by Hitachi Chemical Co., Ltd.

[0010]

EXAMPLES Next, the present invention will be specifically described with reference to examples.

[0011]

Example 1 R-HM melted at 120 ° C. (manufactured by Hitachi Chemical Polymer Co., Ltd., trade name “Hybon 4820”, viscosity 2)
5000 cP / 120 ℃, maximum open time 7 minutes / 2
(0 ° C.) is surface-coated at about 200 g / m ² on an acrylonitrile-butadiene-styrene resin (ABS) plate: 25 × 100 mm, thickness: 2 mm, and then water containing a curing catalyst (triethylenediamine 3 % Aqueous solution) was applied by spraying at about 30 g / m ² . Then, on this side,
Another ABS plate fixed on the micro-vibration press: 25 x 100 m
m, thickness 2 mm, superposed with an adhesive area of 25 × 25 mm, and applied with a slight vibration of 10 cycles / sec.
A shear adhesion test piece was prepared by performing pressure bonding for 5 seconds at a pressure of cm ² . 3 from R-HM coating to completion of micro vibration bonding
It took 0 seconds. 20 ° C 0.5 hour after adhesion of this test piece
The shear adhesive strength at 7 kgf / cm ² was cohesive failure of R-HM. Also, after leaving it at 25 ° C. and 65% RH for 24 hours, in an atmosphere of 80 ° C., 500 g at one end of the test piece
When a hot holding test was performed by applying a static load of f, it was 5
Showed retention over time.

[0012]

Comparative Example 1 An adhesion test was conducted in the same manner as in Example 1 except that water containing a curing catalyst was not applied. Shear bond strength at 20 ° C. after 0.5 hour of adhesion is 7 kgf / cm ² and is RH
It was M's cohesive failure. However, in the hot holding test after standing for 24 hours, the adhesive portion was detached due to cohesive failure within 0.5 hours.

[0013]

[Comparative Example 2] 0.5 kgf without applying slight vibration during crimping
An adhesion test was performed in the same manner as in Example 1 except that static pressure bonding was performed for 5 seconds at a pressure of / cm ² . The shear bond strength at 20 ° C. after 0.5 hour from adhesion was 4 kgf / cm ² , and interfacial fracture was partially observed. In addition, in the hot holding test after standing for 24 hours, after 0.5 hours, the adhesive portion was detached due to cohesive failure.

[0014]

As described above, according to the bonding method of the present invention, it is possible to obtain a highly reliable adhesive having excellent initial adhesiveness, quick development of hot holding characteristics, and short-time bonding. . Therefore, the bonding method of the present invention can be effectively used for bonding parts such as automobiles and building materials.

Claims (2)

[Claims] 1. A moisture-curable reactive hot melt adhesive is applied to at least one of the adherends, and water containing a curing catalyst is applied to the adherend surface and / or the applied adhesive surface. Then, the bonding method is characterized in that the adherend is subjected to micro-vibration of 1 cycle / second or more and pressure-bonded. 2. A moisture-curable reactive hot melt adhesive,
The bonding method according to claim 1, which is a crystal solidification type having a solidification time of 2 minutes or more at a coating temperature of 90 to 140 ° C.