JPH02276635A - Manufacture of thermosetting adhesive sheet - Google Patents

Abstract

PURPOSE:To improve the adhesion strength and the heat resistant property after the curing under heating, while the adhesion property at room temperature is provided by a method in which specific epoxy resin is preliminarily reacted with specific 1,2-polybutadiene in a specific proportion at specific temperature, and latent curing agent and curing catalyst are compounded therewith, and then a base is coated and impregnated with said material so as to be kept in uncured or semicured state. CONSTITUTION:Polybutadiene-epoxy resin is obtained by reacting the epoxy resin of 100pts.wt. having at least two epoxy radicals in one module with the 1,2-polybutadiene of 5-50pts.wt. shower by the formula (n is an integer of at least 5) and having carboxyl radical in terminal at 80-200 deg.C, and a base is coated and impregnated with the thermosetting resin composition of solventless type obtained by compounding potential curing agent and curing catalyst with said polybutadiene-epoxy resin so that said resin composition is kept in uncured or semicured state. Consequently, the thermosetting adhesive sheet having the adhesion property at room temperature and showing the remarkably excellent adhesion property in the curing under heating, may be obtained.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for producing a thermosetting adhesive sheet.

More specifically, the present invention relates to an adhesive sheet that has tackiness at room temperature and has the property of being cured by heating.

[Conventional technology]

Adhesive sheets used for electrical applications such as coil winding and wire bundling in various electrical devices are prone to peeling due to softening of the adhesive at high temperatures, or dissolution of the adhesive during immersion in varnish or various solvents. It is necessary to prevent the adhesive from peeling off, and therefore the adhesive is cured by heating during use.

One method for manufacturing such adhesive sheets has traditionally been to use a varnish made by diluting an epoxy resin composition with a specific organic solvent.
A known method is to impregnate a sheet-like base material and hang an adhesive sheet, but this method has problems such as environmental pollution due to organic solvents, void generation when the solvent evaporates, and reduced moisture resistance due to residual solvent. .

For these reasons, a method of adding a high molecular weight phenoxy resin with an average molecular weight of m10,000 or more has been adopted as a material that provides excellent adhesive properties without impairing tackiness at room temperature (Japanese Patent Laid-Open No. 59-108072). (see official bulletin).

[Problem to be solved by the invention]

However, the addition of phenoxy resin lowers the glass transition temperature, which is one of the important properties inherent in epoxy resins, leading to disadvantageous results.

There is also a method of adding high molecular weight epoxy resin,
Although a thermosetting adhesive sheet having the desired room-temperature tackiness could be obtained, the melt viscosity was too high, resulting in poor flow characteristics, which was undesirable in terms of workability, and unsatisfactory in terms of practicality.

(Means for solving the 11 problems) In order to solve these problems, as a result of intensive research, the present invention has developed an epoxy resin having at least two epoxy groups in one molecule (hereinafter referred to as a specific epoxy resin). (also referred to as resin) 100 parts (11 parts, the same shall apply hereinafter) and 1,2-polybutadiene (hereinafter referred to as A solvent-free thermal resin made by blending a latent curing agent and a curing catalyst into a polybutadiene-epoxy resin obtained by reacting 5 to 50 parts of specific 1,2-polybutadiene at 80 to 200°C. By coating and impregnating a curable resin composition onto a base material so that the resin composition is in an uncured or semi-cured state, it has tackiness at room temperature and exhibits very good adhesive properties when cured by heating. It was discovered that a new and useful thermosetting adhesive sheet could be obtained, and the present invention was completed.

[For production]

The thermosetting resin composition (adhesive) used in the present invention is
A specific epoxy resin as the main component and a specific 1゜2-polybutadiene are pre-reacted at 80 to 200℃ to improve compatibility, and after curing, the epoxy network and polybutadiene network are balanced in the cured network. They will coexist well. This allows for very good adhesive properties to be developed without lowering the glass transition point, giving a cured adhesive layer with high tensile shear strength and peel strength. In addition, since it exhibits an appropriate melt viscosity, the coating and impregnating workability is good. Moreover, since it is a solvent-free type, it is not only sanitary and economical, but also has the advantage of not producing any voids and causing no deterioration in moisture resistance.

〔Example〕

The epoxy resin used in the present invention may have at least two epoxy groups in one molecule, and conventionally known epoxy resins can be used.

Specific examples of such epoxy resins include bisphenol A epoxy resin, bisphenol F epoxy resin, resorcinol epoxy resin, tetrahydroxyphenylethane epoxy resin, Talesol novolac epoxy resin, polyolefin epoxy resin,
Examples include alicyclic epoxy resins and their halides.

One type of epoxy resin may be used, or two or more types may be used in combination.

The 1,2-polybutadiene having a carboxyl group at the end represented by the general formula (1): (wherein n is an integer of 5 or more) used in the present invention has a polymer chain in which 90% or more is 1,2-polybutadiene. “atac” consisting of a bond
tic j 2-polybutadiene is a pendant vinyl polymer with branched vinyl groups.

In addition, the number average molecular weight is 5 to maintain good adhesive properties.
It is preferable to use a polybutadiene resin having a molecular weight of 00 or more, and more preferably a range of about 1,000 to 5,000.

A commercially available product of 1,2-polybutadiene having a carboxyl group at its terminal includes, for example, Nl5SO-PB-C-1000 manufactured by Nippon Soda.

In the present invention, a polybutadiene-epoxy resin obtained by reacting a specific epoxy resin with a specific 12-polybutadiene is used.

The reaction is carried out at a temperature of 80°C to 200°C, preferably 100 to 15°C.
The reaction is carried out at a temperature of 0°C for several hours, usually from 1 to 8 hours, without a catalyst or in the presence of a catalyst (benzyltrimethylammonium bromide, tetraethylammonium bromide, etc.).

If the reaction temperature is less than 80°C, the reaction time will be shortened, whereas if it exceeds 200°C, the reaction time will be shortened, but reaction control will become difficult, both of which are unfavorable from a work standpoint.

The mixing ratio of the epoxy IN resin and 1,2-polybutadiene is 5 to 50 parts, preferably 10 to 40 parts, per 100 parts of the epoxy resin.

If the proportion is less than 5 parts, the cohesiveness of the thermosetting resin composition will be insufficient and the adhesive strength at room temperature will be weak, and if it exceeds 50 parts, the cohesiveness will be too strong and the coating impregnation properties on the substrate will be impaired. The fluidity during heat curing also deteriorates, both of which are undesirable.

In the present invention, a solvent-free thermosetting resin composition is prepared by blending a latent curing agent and a curing catalyst with the polybutadiene-epoxy resin, and further blending a vinyl polymerization initiation catalyst if necessary.

The latent curing agent, curing catalyst, and vinyl polymerization initiation catalyst are used when coating and impregnating a base material with a resin composition at a normal temperature of 60 to 100°C without curing the composition (even if it is semi-cured). Various types of adhesives can be used as long as they cure quickly when heated to a high temperature of over 100°C.

Specific examples of the latent curing agent include dicyandiamide, dicyandiamide modified products, phenolic resins, and boron trifluoride amine complex salts.

Examples of the curing catalyst include tertiary amines such as benzyldimethylamine (B, D, H, A, ), 2-(dimethylaminemethyl)phenol, 2-ethyl 4
Examples include imidazoles such as -methylimidazole and 1-benzyl-2-methylimidazole.

Examples of the vinyl polymerization initiation catalyst include organic peroxides such as dicumyl peroxide, t-butyl perbenzoate, t-butyl peroxylaurate, and benzoyl peroxide.

The amounts of these components added may be the usual amounts, and the latent curing agent is usually 1 to 30 parts, preferably 3 to 10 parts, and the curing catalyst is 0.1 parts to 100 parts of the polybutadiene-epoxy resin. ~5 parts, preferably 0.3 to 1 part, vinyl polymerization initiation catalyst 0.01 to 5 parts, preferably 0.05 to 2 parts
Department.

There is no problem in adding pigments and other known fillers to the resin composition used in the present invention, if necessary. The amount of these components to be added may be the amount commonly used in the layer, and is preferably used in the range of 20 to 150 parts with respect to the resin composition 100a11.

Next, the resin composition is coated and impregnated onto a base material so as to be in an uncured or semi-cured state to obtain a thermosetting adhesive sheet having room temperature tackiness.

The base material may be selected as appropriate depending on the application of the adhesive sheet, and includes, for example, inorganic 11M cloth made of glass, alumina, etc., organic III cloth made of nylon, polyester, vinylon, etc., film made of nylon, polyester, etc., and polyamide. Examples include paper. The fiber cloth may be a nonwoven fabric. Among these, polyester nonwoven fabrics and glass fiber cloths are particularly preferred from the viewpoint of manufacturing process. Moreover, the thickness of the base material is usually 50 to 125ρ.

There is no particular limitation on the method of coating and impregnation, but the resin composition
It is preferable to carry out the coating and impregnating process while heating it to 0 to 100°C, and the coating and impregnating may be carried out using a hot roll, a comma coater, or the like.

There are no particular limitations on the coating thickness and coating amount on the base material, but
To provide good adhesion properties, a coating thickness of 0.05
~1.5 cm, coating ml 100~200g/yd
is preferred.

The above-mentioned uncured or semi-cured state is a state where curing is not completely completed, that is, a state where the curing reaction is stopped midway! 1
m (B stage state).

The thermosetting adhesive sheet of the present invention having room-temperature tackiness obtained in this way can provide very good adhesive properties and excellent flow properties by heating and curing it with or without pressure. It can be widely used not only as an adhesive for electrical and electronic parts, but also for semi-structural adhesive sheets and other general purposes.

Next, the present invention will be explained in more detail based on Examples, but the present invention is not limited to these Examples.

Example 1 As epoxy resins, 70 parts of Epicoat 828 (manufactured by Yuka Shell Epoxy ■, epoxy equivalent 184 to 194) and DEN-438 (manufactured by Dow Chemical Company, epoxy equivalent 1) were used as epoxy resins.
76-181) and 25 parts of old 5SO-PB-C-1000 as 1,2-polybutadiene (manufactured by Nippon II DatsuM, number average molecule m 1200-1500) were placed in a reaction vessel, and benzyltrimethylammonium was added as a catalyst. Add 0.1 g of bromide and heat at 100-120℃ for 6 hours.
After a period of reaction, a polybutadiene-epoxy resin was obtained.

Thereafter, the temperature was lowered to 80-90°C, 4 parts of dicyandiamide was added, and after heating and stirring for 30 minutes, 2-ethyl-
0.1 part of 4-methylimidazole (manufactured by Shikoku Kasei Kogyo ■) and 0.5 part of dicumyl peroxide (manufactured by Wako Tsumugi Kogyo ■) as a vinyl polymerization initiation catalyst were added, and the mixture was heated and mixed for an additional 5 minutes. The mixture was rapidly taken out from the reaction vessel and cooled to room temperature to obtain a solvent-free thermosetting resin composition having tackiness at room temperature.

This composition was applied to glass cloth (manufactured by Asahi Siebel Co., Ltd., product name:
Number 1080, density: 49.2! ? / TIt) and a heat roll (temperature 90-100°C) via a separator
A thermosetting adhesive sheet having normal temperature tackiness was obtained by impregnating the substrate with a coating amount of 140 g/TIt.

In order to check the adhesive strength of the obtained adhesive sheet at room temperature,
Paste the sample cut out to a width of m on a stainless steel plate, and
After pressing for 1 minute at a pressure of Ky/d, one end of the sample was
It was bent at 80 degrees and peeled off at a speed of 50 M/min to determine the adhesive strength at room temperature. In addition, in order to determine the adhesive strength after curing, three of the sample pieces were placed between two rolled steel plates with a thickness of 1.6 HR.
The sheets were stacked, heat pressed at 150°C for 30 minutes, and post-cured at 170°C for 6 hours, after which the shear adhesive strength at room temperature and 150°C was measured according to JIS K6850. Furthermore, in order to determine the glass transition temperature after curing, one of the samples was cured at 170° C. for 6 hours, and the glass transition temperature was measured by thermomechanical analysis (THA). The results are shown in Table 1.

Example 2 GV-255 (manufactured by Ciba Geigy) was used as an epoxy resin.
Epoxy equivalent 174-184) 60 parts and DEN-4
31 (manufactured by Dow Chemical Company, epoxy equivalent 172-179
) 40 parts and 1,2-polybutadiene as the former 5SO-
Example 1 except that 40 parts of PB-C-100 was used.
A resin composition II was prepared in the same manner as in Example 1.
The substrate was coated and impregnated in the same manner as above to obtain a thermosetting adhesive sheet with room temperature tackiness. The properties of the obtained adhesive sheet were evaluated in the same manner as in Example 1. The results are shown in Table 1.

The base material is polyamide paper (manufactured by Nippon Vilene ■,
Product name: KH-3003CT, density: 27g/TIL
), and the coating amount was 130 g/yd.

Example 3 As epoxy resins, 50 parts of Epicoat 807 (manufactured by Yuka Shell Epoxy ■, epoxy equivalent weight 160 to 175) and 50 parts of Epicoat 152 (manufactured by Yuka Shell Epoxy ■, epoxy equivalent @ 172 to 179) were used, and 1.2- A resin composition was prepared in the same manner as in Example 1, except that 10 parts of NrSSO-PB-C-1000 was used as the polybutadiene, and this was applied and impregnated onto a substrate in the same manner as in Example 1. A thermosetting adhesive sheet with room temperature tackiness was obtained.

A polyester nonwoven fabric (manufactured by Nippon Vilene ■, product name: H-8103, density: 30 parts m) was used as the base material, and the coating amount was 135 g/Trt. The properties of the obtained adhesive sheet were evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 1 As an epoxy resin, 70 parts of DER-332 (manufactured by Dow Chemical Company, epoxy weight m172-176), DER-6
61 (manufactured by Ri'7'y Mical Co., Ltd., epoxy equivalent: 500~
560) into a reaction vessel, melt and mix at 90 to 100°C, and after confirming complete melting, add dicyandiamide 4.
0.29 of 2-(dimethylaminomethyl)phenol (manufactured by Wako Tsumugi Kogyo), and then 30
The mixture was heated and mixed for 0 minutes to obtain a thermosetting resin composition.

A thermosetting adhesive sheet was obtained using this composition in the same manner as in Example 1. Since no polybutadiene-epoxy resin was added, the adhesive strength at room temperature was poor, and the desired adhesive sheet could not be obtained. The properties of the obtained adhesive sheet were evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2 828,100 parts of Epicoat as an epoxy resin and 30 parts of a phenoxy resin with an average molecular weight of 130,000 (manufactured by Union Carbide Co., Ltd., product name: PKHH) were placed in a reaction vessel, and the mixture was melted and mixed at 180 to 200°C for 2 hours until completely dissolved. After confirming that, the temperature was lowered to 90-100°C, 6 parts of dicyandiamide was added, and 0.2 g of 2-ethyl 4-methylimidazole was added, and the mixture was heated on a heating stand for 30 minutes to form a thermosetting resin composition. did.

A thermosetting adhesive sheet was obtained using this composition in the same manner as in Example 1. However, the heat roll temperature was the same as in Example 1.
When the temperature was set at 0 to 100°C, the melt viscosity was too high to coat, so the hot roll temperature was set at 130 to 140°C. In addition, in such warm coating, the resin composition began to gel in less than 30 minutes, and continuous coating was not possible. The properties of the obtained adhesive sheet were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Margin below]

From the above results, it can be seen that the thermosetting adhesive sheet of the present invention has excellent workability, has room temperature tackiness, and has excellent adhesive strength and heat resistance properties after heat curing.

〔Effect of the invention〕

The thermosetting adhesive sheet of the present invention has tackiness at room temperature and has excellent adhesive strength and heat resistance properties after heat curing, and is of extremely great industrial value.

representative person Large rock Masu male Display of incidents ↑To the condyle name of invention Manufacturing method of thermosetting adhesive sheet 3. Person who makes corrections Relationship with r1c matter

Claims (1)

[Claims] (1) 100 parts by weight of an epoxy resin having at least two epoxy groups in one molecule and the general formula (I): ▲Mathematical formula, chemical formula, table, etc.▼(I) (In the formula, n is 5 or more. 1,2-polybutadiene having a carboxyl group at the end represented by an integer 5 to 5
A solvent-free thermosetting resin composition is prepared by blending a latent curing agent and a curing catalyst into a polybutadiene-epoxy resin obtained by reacting 0 parts by weight with 0 parts by weight at 80 to 200°C.
A method for producing a thermosetting adhesive sheet, which comprises coating and impregnating a base material with the resin composition in an uncured or semi-cured state.