JPH01156389A - Bonding method - Google Patents

Abstract

PURPOSE:To accomplish bonding in a low temp. atmosphere within a short period of time and avoid the occurrence of defectives, such as peeling, by heating bonded parts by means of a flexible face heating device after application of the adhesive and joining of parts to be bonded, in performing bonding by the use of an adhesive of a room-temp. curable thermosetting resin compsn. CONSTITUTION:In performing bonding by the use of an adhesive of a room-temp. curable thermosetting resin compsn., the adhesive is applied to the parts to be bonded of an adhered. Then, the parts to be bonded are joined and heated by the use of a flexible face heating device disposed in the neighborhood thereof so as to cure the adhesive. Pref. examples of the adhesive include an adhesive of a radical-curable thermosetting resin compsn., and pref. examples of the adhered include a marble-like resin product. It is pref. that the calorific value of the face heating device ranges from 100-1,000W/m<2>.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention enables bonding work in a low-temperature atmosphere in bonding work using an adhesive made of a room-temperature curable thermosetting resin composition, and The present invention provides a new bonding method that can shorten the time required for work and is free from accidents such as peeling.

(Prior art) Adhesion using an adhesive made of a thermosetting resin composition that cures at room temperature is widely practiced because it has high adhesive strength, is relatively easy to work with, and does not require special equipment. It is being said. However, the curing time of such adhesives is strongly influenced by ambient temperature, and when adhesive work is performed in a low-temperature atmosphere, it takes a long time to harden, which tends to impair workability.

In order to improve this problem, adjusting the amount and type of curing agent in the composition used for adhesives has been considered, but such methods have limitations, such as
At present, it is extremely difficult to perform bonding work at temperatures around ℃. In particular, in applications where the color tone of the adhesive is a problem, there are restrictions on the type and amount of curing agent that can be used, and for example, it is extremely difficult to bond marble-like resin articles. .

On the other hand, various attempts have been made to improve the workability of bonding by heating the bonded portion. For example, there is a method of shortening the curing time of the adhesive by blowing hot air using a hair dryer or the like, or heating the adhesive part with a heating means such as an infrared heater or an electric blanket. However, when humidifying with this method, although it is possible to shorten the curing time of the adhesive, the humidification tends to be uneven, and a wider area is heated more than necessary, so When heating is stopped, a large amount of residual stress remains due to thermal contraction of the adherend, which tends to cause defects such as peeling of the bonded part. <Problems to be Solved by the Invention> The present invention aims to solve these problems.

Therefore, an object of the present invention is to be able to complete bonding in a low temperature atmosphere in a short time in a bonding work using an adhesive made of a thermosetting resin composition that cures at room temperature, and without causing problems such as peeling. The objective is to provide a highly reliable bonding method.

(Means and effects for solving the problems) As a result of various studies to solve these problems, the inventors of the present invention found that after applying adhesive, a flexible sheet heating element was used. It was discovered that the intended purpose could be achieved by heating the bonded portion, leading to the present invention.

That is, in the present invention, when bonding is performed using an adhesive made of a thermosetting resin composition that cures at room temperature, the adhesive is first applied to the part of the adherend to be bonded, and then the part to be bonded is The present invention relates to a bonding method characterized in that the adhesive is hardened by pressing a flexible planar heating element against and heating the adhesive near the portion to be bonded.

The adhesive made of a room-temperature curable thermosetting resin composition used in the present invention is an adhesive that can be cured at around room temperature, and is generally used by mixing a base agent and a curing agent immediately before use. A liquid type adhesive. Such adhesives are mainly composed of thermosetting resins such as epoxy resins, urethane resins, acrylic resins, and unsaturated polyester resins mixed with various additives, and are also made of amines and polyesters that react with these resins. Examples include those using a hydric alcohol or a radical polymerization initiator as a curing agent. Among them, when using an adhesive made of a room temperature curing thermosetting resin composition that uses a radical curing thermosetting resin such as acrylic resin or unsaturated polyester resin as the main ingredient, it has good workability and It is also desirable that coloring can be minimized.

The flexible planar heating element used in the present invention is a planar flexible planar conductor covered with a flexible insulator, and generates heat by passing electricity through the planar conductor. It is configured to do so. In general, carbon thin films, conductive l1itiTI mixed paper, metal thin films, etc. are used as planar conductors.
Furthermore, a plastic film, rubberized cloth, or the like is used as the insulator, but the structure thereof is not particularly limited.

In addition, the shape and size of the sheet heating element can be selected as appropriate depending on the shape of the adherend and the size of the bonded part, but a thin band-shaped sheet heating element is preferable in terms of workability and adhesion effectiveness. desirable. In other words, in order to obtain an excellent adhesive effect without problems such as peeling in the present invention, it is necessary to limit the area heated by the sheet heating element to a narrow area near the adhesive part, and to The body responds well to this request. Furthermore, it is desirable that the width of the band-shaped sheet heating element be within a range of 2 to 10 times the thickness of the adherend. If the width of the sheet heating element is less than twice the thickness of the adherend, it will be difficult to heat the bonded area uniformly, and if it exceeds 10 times the width, the heat of the adherend will increase after heating is stopped. Residual stress associated with shrinkage tends to increase, which is both unfavorable. Further, the length of the band-shaped planar heating element may be selected to be sufficient to cover the entire adhesive portion.

The heating value of the planar heating element is 100 watts/71'12~1
000 watts/m, preferably in the range of 2.000 watts/m. When the calorific value is less than 100 watts/m2, it is difficult to efficiently heat the bonded portion, and the effect of improving workability is small. On the other hand, if it exceeds 1000 watts/T112, the temperature of the bonded part will be too high, and the residual stress due to thermal contraction of the adherend after heating will tend to increase.

The adherend used in the present invention is preferably a material that can be efficiently and partially heated with a planar heating element. For example, materials with high thermal conductivity such as metals are difficult to locally heat using the bonding method of the present invention and tend to be heated over a wide range, which is not desirable in terms of residual window horns. On the other hand, materials with low thermal conductivity, such as plastic foam, tend to be heated locally, which is not desirable because only the surface in contact with the planar heating element is heated. Therefore, the method of the present invention is particularly effective when the adherend is a material having thermal conductivity between these intermediates. Among these, when the adherend material is a marble-like resin article,
It is desirable because it has appropriate thermal conductivity and can be heated without generating residual stress.

Next, a method of implementing the present invention will be specifically explained.

First, an adhesive made of a thermosetting resin composition that cures at room temperature is applied to the adhesive portion of the adherend, and the adhesive is fixed by an appropriate method. At this time, if the adhesive is protruding from the adhesive part, place a film with good releasability such as Tetron film on the protruding adhesive as necessary, so that the protruding adhesive can be removed from the sheet heating element. It may be possible to avoid direct contact.

- Thereafter, a flexible planar heating element is pressed near the bonded portion and heated by applying electricity. At this time, the sheet heating element is
There is no need to press it particularly hard; just placing it on the surface of the adherend near the adhesive part will be sufficient to exert its effect. If it is necessary to press the sheet heating element against the vertical or lower surface of the adherend or to heat it along the curved surface of the adherend, it may be fixed with cellophane tape or the like.

If the calorific value of the planar heating element is selected within an appropriate range, temperature control such as a thermostat is not particularly required. The adherend is gradually heated, and eventually the heat generation and heat radiation become equal and reach an equilibrium temperature. Empirically, it is desirable that the equilibrium temperature does not exceed 60° C. in order to minimize residual stress.

The area on which the planar heating element is pressed can be selected arbitrarily as long as the vicinity of the bonded area can be heated almost uniformly. For example, when the side surfaces of a plate-shaped adherend are placed in contact with each other, the planar heating element may be pressed against both the front and back sides of the adherend or only on one side. When pressing a planar heating element against only one side, the temperature difference between the front and back sides of the adherend can be reduced by making the width of the planar heating element at least twice the thickness of the adherend. The area around the adhesive area can be heated almost evenly. However, it is desirable that at least one entire surface of the bonded portion be covered with a planar heating element, and heating only a portion of the bonded portion with a small planar heating element is undesirable as it may cause residual strain. In addition, regarding the temperature distribution of the adherend material in the width direction of the sheet heating element, the temperature drops rapidly on the outside of the sheet heating element, but this phenomenon is due to the generation of residual stress due to heating in areas other than the vicinity of the bonded area. Considering that, this is desirable. Therefore, it is important not to make the width of the planar heating element larger than necessary.

As described above, the adhesive work is completed by heating the vicinity of the bonded portion with the planar heating element and removing the planar heating element after the adhesive has sufficiently hardened.

(Effects of the Invention) According to the bonding method of the present invention, bonding work using an adhesive made of a room-temperature curable thermosetting resin composition in a low-temperature atmosphere can be completed in a short time, and the bonding process can be completed in a short time. It is possible to perform highly reliable gluing work without any accidents.

= 10- (Example) The present invention will be explained in more detail with reference to Examples below.

Example 1 When bonding two 12# thick astronomical resin plates (trade name: Marbesheet, manufactured by Nippon Shokubai Chemical Industry Co., Ltd.) at an outside temperature of 0°C, a thermosetting resin composition made of a radical curing type thermosetting resin composition was used. A predetermined amount of a curing agent was mixed with the adhesive (adhesive exclusively for Marbe sheet manufactured by Nippon Shokubai Chemical Co., Ltd.), and then applied to the bonded portion, and the bonded portions were butted together.

A clamp stand for fixing the adhesive part was glued on the astronomical stone-like resin board in advance (Figure 1). Subsequently, the adhesive part was clamped to fix it, and a polyester film with a thickness of 25 microns was covered over the adhesive that protruded from the adhesive part onto the surface of the board (Figure 2). After that, a flexible planar heating element (calorific value 600W/1rL2, width 50#) made of paper mixed with carbon #A fibers and covered with a 0.4# thick soft PVC film was placed along the bonded area. (Figure 3).

When this sheet heating element was energized and left for one hour, 1. The temperature of the surface of the adhesive part is 15°C and the temperature of the bottom surface of the adhesive part is 12°C.
Became. After heating for 1 hour, the adhesive is fully cured.
Even after removing the planar heating element, no defects such as peeling occurred.

[Brief explanation of the drawing]

1, 2, and 3 are perspective views for explaining an embodiment of the bonding method of the present invention. 1. Astronomical resin plate 2, adhesive part 3, clamp stand 4, adhesive 5 protruding from the adhesive part, polyester film 6, clamp 7, planar heating element

Claims (1)

[Claims] 1. When bonding is performed using an adhesive made of a thermosetting resin composition that cures at room temperature, the adhesive is first applied to the part of the adherend to be bonded, and then the adhesive is applied. 1. A bonding method comprising: joining parts to be bonded, and then pressing a flexible sheet heating element near the parts to be bonded and heating to cure the adhesive. 2. The adhesion method according to claim 1, wherein the adherend is a marble-like resin article. 3. The heating value of the planar heating element is 100 watts/m^2~10
The bonding method according to claim 1, wherein the adhesiveness is in the range of 00 watts/m^2. 4. The bonding method according to claim 1, wherein the adhesive is an adhesive made of a radical-curable thermosetting resin composition.