JPS6026518B2 - Manufacturing method of adhesive sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an adhesive sheet using thermosetting resin powder, and is mainly used for insulation and adhesive protection materials.
In particular, the present invention relates to a method for manufacturing an adhesive sheet with excellent punching workability that can be suitably used as a precision adhesive material for electrical and electronic materials.

Accordingly, this type of adhesive sheet is manufactured by a so-called solution coating method in which a synthetic resin is dissolved in a solvent and then impregnated into the fiber base material, but this solution coating method can generally only use resins that can be dissolved in the solvent. There are limitations, and if the solution viscosity increases, it will not adapt to the coating process, so it is not possible to increase the resin concentration.
When attempting to coat a resin containing an inorganic filler, etc., there is a drawback that the filler settles in the solution and cannot be coated.

Therefore, it is common to use a resin that does not use filler or contains almost no filler, and dissolves it in a solvent at a relatively low concentration and applies it to the base material, but even with this method, an adhesive sheet with a large amount of resin impregnation can be obtained. If you try to use a large amount of solvent, voids may occur due to the dispersion of the solvent during the formation of the resin layer, or undispersed solvent may remain in the layer even after the resin layer is formed, causing the sheet's moisture resistance to deteriorate. There are disadvantages in that the properties of the adhesive sheet may be impaired, and that the uncured dispersion solvent may scatter during use of the adhesive sheet, causing voids.

In recent years, in response to the demand for an adhesive sheet manufacturing method that does not involve the scattering of organic solvents in order to replace the solution coating method, which has such drawbacks, and from a sanitary perspective, resin powder can be directly applied to fibers without using solvents. A method of manufacturing an adhesive sheet using a so-called powder coating method has been proposed, in which a powder layer of a predetermined thickness is first formed by disposing the powder on a substrate, and then heated and melted to impregnate the inside of the substrate.

In addition, in this method, if external pressure is applied when the resin is impregnated and integrated, that is, when it is heated and melted, the impregnation performance, sheet thickness accuracy, and bubble-free property are significantly improved compared to the case where no external pressure is applied. It is known to give good results. These powder coating methods can overcome the various drawbacks seen in conventional solution coating methods, and can therefore be said to be industrially advantageous.

However, when a thermosetting resin powder is selected and used as the resin powder, there is a problem in that the resin powder falls off during handling such as punching as a result of the sheet itself lacking in flexibility. For example, when an adhesive sheet obtained by such a method is punched and cut into small pieces of a predetermined shape or slit into a tape shape, the resin near the cut pieces breaks off and falls, creating a missing part of the resin in the base material. This has the disadvantage of causing poor adhesion and contaminating the adherend when the resin is scattered to parts of the adherend that do not require adhesion.

As a result of intensive studies in light of the above circumstances, the inventors have found that the above-mentioned problem can be solved by treating the base material with a specific treatment liquid as a primer before coating the thermosetting resin powder on the base material. This led to the completion of this invention.

That is, this invention consists of coating a thermosetting resin powder on a fiber base material that has been primed with a treatment liquid containing a soft resin mainly composed of a thermosetting resin, and then subjecting it to a heat melting treatment. Production of an adhesive sheet with excellent punching workability, characterized in that the amount of the soft resin adhered to the fiber base material is in the range of 2 to 2% by weight in total including the amount of coated thermosetting resin powder. It concerns the law.

In this way, in this invention, the fiber base material is treated with a treatment liquid containing a European resin before powder coating, so a certain amount of the soft resin adheres to the base material, and in this state, it becomes thermosetting. When the resin powder is applied and heated and melted, the resin and the powder are partially melted and integrated, so that the adhesion of the powder to the substrate is significantly improved.

Moreover, since the entire sheet can be made flexible by the presence of the soft resin, falling off of the resin during punching or other handling is significantly suppressed compared to a case where such pretreatment is not performed. Furthermore, the above pretreatment not only improves the punching workability as described above, but also prevents the resin from falling off during resin powder coating. That is, when a fiber base material with low density or thin wall is used and the above pretreatment is not performed, a part of the resin powder may slip through the base material during powder coating. However, by performing the pretreatment according to the method of the present invention, such slip-through of the resin powder can be effectively prevented, and a certain amount of the resin powder can be uniformly applied to the entire fiber base material. Furthermore, as a result of such excellent punching workability and good powder coating properties, good results can be obtained in terms of the adhesive strength of the adhesive sheet, and the heat resistance strength as a thermosetting resin powder can be obtained. Other characteristics can be fully utilized.

The treatment liquid used in this invention is made by appropriately dissolving a soft resin in various organic solvents such as ketone, alcohol, trichlene, toluene, etc., and its viscosity is 100 poise at the substrate pretreatment temperature (usually 100°C or less). The following are desirable. By using such a treatment liquid, the entire fiber base material can be treated uniformly and favorably. The above-mentioned rope resin has more flexibility than thermosetting resin powder, and from the viewpoint of heat resistance etc., it can be appropriately selected from those mainly composed of thermosetting resin depending on the type of resin powder. . In general, thermosetting resins that are fluid or semi-solid at room temperature, mixed resins in which some thermoplastic resins are added, or mixtures of these with thermosetting resins that are solid at room temperature can also be used. Among such soft resins, particularly desirable ones are those that are relatively well compatible with the thermosetting resin powder.

If the compatibility is good, when heating and melting after powder coating,
The soft resin and the powder resin are easily fused and integrated, and good results are obtained due to the adhesion of the silk fruit and the powder resin to the base. In addition to the above-mentioned compatibility, it is desirable that the material has tackiness at room temperature. The reason for this is obvious: having adhesive properties can further prevent the resin powder from slipping through or falling off during powder coating and punching. Specific examples of soft resins include epoxy resin, phenol resin, polyester resin, nylon, polybutyral resin, formal resin, polysulfone, phenoxy resin, ethylene-vinyl acetate copolymer, liquid rubber, and modified products thereof. . Note that since a thermosetting resin is used as the soft resin, a curing agent for this resin can be included in the processing liquid, but generally such a curing agent need not be used. The reason for this is that the curing agent contained in the thermosetting resin powder partially migrates to the soft resin side during heating and melting, thereby making it possible to harden the soft resin as well. In this invention, the fiber base material is treated with a primer using a treatment liquid containing the above-mentioned European resin, but the amount of soft resin adhered to the base material is usually the same as the total amount of the thermosetting resin powder coated. Preferably, the amount is in the range of 2 to 2% by weight.

If the above-mentioned amount of adhesion is too small, the effect of this invention cannot be obtained,
On the other hand, if the amount is too high, the significance of using thermosetting resin powder will be lost, and the advantages of powder coating methods, such as suppressing void generation and improving moisture resistance, will be lost, and the adhesive strength, heat resistance, etc. I can't get good results either. Fiber materials that can be treated with a primer include woven fabrics, non-woven fabrics, and mats made of natural organic, synthetic organic, or inorganic fibers, and even if these are relatively thin and have low density, they can be bonded. It can be widely applied as long as it has the mechanical strength required as a flexible sheet. After such a fiber base material is treated with a primer, it is usually air-dried and then subjected to a coating process with thermosetting resin powder.

The organic solvent in the treatment liquid is volatilized and removed by the above-mentioned air drying, but even if some remains, it is completely removed by the heating and melting treatment after powder coating. In some cases, it is also possible to evaporate all the organic solvents during the heating and melting treatment without air drying. The thermosetting resin powder used for powder coating is one that contains epoxy resin, other thermosetting resin, or a part of thermoplastic resin, a hardening agent, and if necessary, an inorganic filler, various additives, and a small amount of organic It is obtained by pulverizing a blend containing a solvent to a particle size usually below 300 A, preferably in the range of 250 to 50 A.

Powder coating methods can be widely applied as long as they can form a powder layer of uniform thickness, but generally, spray coating methods,
An electrostatic coating method, a spray coating method, a fluidized dip coating method, etc. are preferably employed.

After this powder coating, heating and melting treatment is performed to produce the adhesive sheet of the present invention.

What is important here is that temperature conditions must be selected so that the thermosetting resin powder does not harden. Through this treatment, the coating powder and the soft resin are partially fused and integrated at the interface, and the adhesion of the powder coating to the base material and the flexibility of the entire sheet are achieved. In order to enhance this effect, it is desirable to apply external pressure during heating and melting. When external pressure is applied, air bubbles and organic solvents in the soft resin and coating powder related to primer treatment are easily extruded, which promotes bubble-free formation of the resulting adhesive sheet, and also improves the impregnability of the resin and the sheet. Good results can also be obtained in terms of thickness accuracy. In the method of heating and melting by applying external pressure,
After powder coating, it is practically desirable to perform a two-step process of first heating and melting in a non-pressurized state and then reheating and melting under pressure.

The main purpose of the first stage of heating and melting is to sufficiently fix the coating powder on the substrate, while the second stage of heating and melting aims to maximize the effects of the present invention. In the above pressing method, for example, a heated roll press or a heated press plate is used to interpose a Shigeru-shaped film on both the upper and lower surfaces of the powder-coated Motomura, and the pressure is usually 0.2 to 0.2 mm from both sides.
Heat pressing may be carried out under the conditions of 40k9/kg, 50-200qo, 12 minutes or less, preferably 0.5-5k9/kg, 80-180qo, 5 minutes or less. Examples of the present invention will be described below to explain it more specifically.

Note that in the following, parts and % mean parts by weight and % by weight, respectively. Example 1 Epoxy resin (Epicote #8 manufactured by Yuka Shell Epoxy Co., Ltd.
28) Dissolve 6 parts and 4 parts of phenoxy resin (PKHH manufactured by Union Carbide Co., Ltd.) in methyl ethyl ketone,
Primer A was prepared with a resin content of 15% and a viscosity (25° C.) of 10 to 20 voids.

Next, 10 sparse parts of an epoxy resin (Epicote #1002 manufactured by Yuka Shell Epoxy Co., Ltd.), 2-undecyl imidazole (
A mixture consisting of 1 part (manufactured by Shikoku Kasei Co., Ltd.) and 3 parts of carbon black (manufactured by Mitsubishi Kasei Co., Ltd.) was roll-kneaded for 1 time in a looocoC and then ground in a hammer mill to give an average particle size of 8.
Resin powders of 0 to 200 degrees were created.

The gelation time of this powder was 2 minutes and 30 seconds at 150oo. Next, the primer A was coated with glass cloth (trade name 216-AS3 female, manufactured by Asahi Schwebel Co., Ltd.; 110 days/day,
The film was impregnated and coated on a vertical 6-piece, horizontally mottled book/inch, and the organic solvent was removed by air-drying.

The amount of primer applied was 7 days/month based on the resin content. Thereafter, the resin powder was coated onto the primer-treated glass cloth using a gravure roll with slits so that the amount of resin powder was 100 mm per coat, and was fixed by heat treatment at 12 mm for 2 minutes. In this treatment, the organic solvent in the primer was completely removed. After that, a polyester release film (thickness 50r) treated with silicone resin was placed on both sides of the glass cloth base material, and 120qo, 3k9/
The adhesive sheet of the present invention was prepared by pressure and heat treatment at a rate of 0.5 kites/min. Example 2 Epicoat #828 (previous life) 70 copies, Epicoat #10
02 (mentioned above) 3 eaves part was dissolved in a mixed solvent of methyl ethyl ketone and methanol to give a resin content of 20% concentration and viscosity (2
○) Brimer B of 7 to 15 poise was prepared.

Next, 40 parts of epoxy resin (Epicoat #1004 manufactured by Yuka Shell Epoxy Co., Ltd.), 6 parts of Epicoat #1002 (mentioned above)
A mixture consisting of 10 parts of phenol resin (product name: M yen 12 eaves, manufactured by Gunei Kagaku Co., Ltd.) and 0.5 parts of 2-methylimidazole was roll-blended for 10 minutes at 10 mm and then hammered. A resin powder having an average particle size of 80 to 200 particles was prepared by pulverizing with a mill.

The gelation time of this powder was 3 minutes at 150 qo. Next, glass cloth (product name 108-A manufactured by Asahi Schwebel Co., Ltd.)
S81: The primer B was impregnated and coated on a 49-thick film (60 vertical lines, 47 horizontal lines/inch), and the organic solvent was removed by air drying.

The amount of primer applied was 6 days/day based on the resin content. Thereafter, the resin powder was applied onto the primer-treated glass cloth using a gravure roll with slits so that the amount of resin powder was 60 mm/day, and heat-treated at 120°C for 5 minutes to coat the base material with the resin. The adhesive sheet of this invention was prepared by impregnation. Note that the organic solvent in the brimer was completely volatilized and removed by the above heat treatment. Example 3 Epiquat #828 (previous generation) was mixed with Ptagene acrylonitrile copolymer rubber (manufactured by Goodrich Co., Ltd. / Aker CTBN1300)
×8) rubber-modified epoxy resin (rubber content: 1
0%) and 35 parts of Epicort #1002 (mentioned above) were dissolved in acetone to give a resin concentration of 15% and a viscosity of (2
0) Primer C was prepared so as to have 10 to 18 poise.

Next, a mixture consisting of 10 parts of Epiquat #1002 (mentioned above), 0.5 parts of 2-undecylimidazole, and 50 parts of trihydrated alumina was roll-kneaded at 10,000 for 10 minutes, and then ground in a hammer mill. Average particle size is 80~200r
resin powder was made.

The gelation time of this powder was 3 minutes and 2 minutes at 150 qo. Then, the Braimer C was impregnated onto a glass cloth (same as described in Example 1), and the organic solvent was removed by air drying.

The amount of primer applied was 7 days/day based on the resin content. Thereafter, the resin powder was coated on this primer-treated glass cloth using a gravure roll with slits so that the amount of resin powder was 110 kg/cm,
It was heat-treated for a minute to fix it in Motomura. Hereinafter, 120 qo, 3 kg was prepared using a roll press in the same manner as in Example 1.
The adhesive sheet of the present invention was produced by pressure treatment under the conditions of 0.5 kite/min. Comparative Example 1 A glass cloth (same as described in Example 1) was coated with the resin powder described in Example 1 at 110 m/m (resin content 50%) without primer treatment. The film was coated directly with a gravure roll with slits, heated at 12 mm for 2 minutes, and then coated with a roll press in the same manner as in Example 1 at 120 qC, 3 kg/0.
An adhesive sheet was prepared by pressure and heat treatment at a rate of 5 skins/min.

Comparative Example 2 The resin powder described in Example 2 was applied to a glass cloth (same as that described in Example 1) at 120 μg/min (resin content 52%) without applying a primer treatment. directly coated with a gravure roll with slits, and then coated with 12
An adhesive sheet was prepared by heat treatment at 0qo for 5 minutes.

Comparative Example 3 A glass cloth (same as described in Example 2) was coated with the resin powder described in Example 2 at a resin amount of 6M/(resin content 55%) without primer treatment.
) was applied directly using a gravure roll with slits, and an attempt was made to create an adhesive sheet by heat-treating this at 120°C for 5 minutes, but the resin powder slipped through the base layer and almost no resin could be applied. .

The punching processability of the six types of adhesive sheets obtained in Examples 1 to 3 and Comparative Examples 1 to 3, the coating status of resin powder,
The results of examining the adhesion to the subject are shown in the table below.

The evaluation method was as follows. <Punching workability> When the adhesive sheet is punched and cut into IQ pine squares using the Thomson method, it is observed with the naked eye whether or not the resin falls off. (0) indicates that there is no problem in use, (△) indicates that there is some falling off and poses a problem in use, and (△) indicates that there is a significant amount of falling off.
×).

<Resin powder coating status> When the resin powder is placed on the base material,
The case where the resin did not slip through was rated as (0), the case where some resin slipped through was observed (△), and the case where the resin slipped through significantly was rated as (×).

<Adhesiveness> An adhesive sheet test piece (adherent was a rolled steel plate) was prepared according to JIS K6850.

The curing conditions were 150°C x 6 generations. The tensile breaking strength of the test piece was measured using an Instron type tensile tester UTM-1-50.
0 fertilizer (manufactured by Toyo Baldwin). As is clear from the above table, the adhesive sheet of the present invention exhibits good punching workability, and even when resin powder is applied, a certain amount of resin is uniformly coated without the resin slipping through the base layer. Furthermore, an improvement in adhesive strength was observed due to improved adhesion between the base material and the resin.

Claims (1)

[Scope of Claims] 1. A thermosetting resin powder is applied onto a fiber base material that has been primed with a treatment liquid containing a soft resin mainly composed of a thermosetting resin, and then heated and melted. Consisting of
Production of an adhesive sheet with excellent punching workability, characterized in that the amount of the soft resin adhered to the fiber base material is in the range of 2 to 20% by weight based on the total amount of the applied amount of the thermosetting resin powder. Law. 2. The method for producing an adhesive sheet with excellent punching workability according to claim 1, wherein the soft resin in the treatment liquid is compatible with the thermosetting resin powder. 3. The method for producing an adhesive sheet with excellent punching workability according to claim 1 or 2, wherein the soft resin in the treatment liquid exhibits adhesiveness at room temperature.