JPH10202814A - Epoxy resin composition-impregnated sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a sheet with good storage stability and application characteristics by preparing a sheet wherein a fibrous base material is impregnated with a compsn. contg. a crystalline epoxy resin and its curing agent and a compsn. contg. a non-crystalline epoxy resin and its curing agent respectively into a layer. SOLUTION: An epoxy resin compsn. A is dispersed uniformly and in a layer on the surface of a fibrous base material and an epoxy resin compsn. B is scattered uniformly and in a layer thereon and are melted or made into a condition being close to this by heating to impregnate the fibrous base material with them and the impregnated material is solidified by cooling. In addition, as the fibrous base material, nonwoven fabrics, woven fabrics, knitted fabrics, etc., comprising fibers such as org. fibers and glass fibers are used. In addition, among two kind of epoxy resin compsn. A and B, the compsn. A comprises a crystalline epoxy resin A and a high m.p. crystalline curing agent A such as bisphenol A and the epoxy resin compsn. B comprises pref. bisphenol type non-crystalline epoxy resin B and its curing agent B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition-impregnated sheet suitable for insulating and fixing electric and electronic parts.

[0002]

2. Description of the Related Art Conventionally, as a sheet impregnated with an epoxy resin composition used for applications such as insulation and fixing of electric and electronic parts, a sheet in which a liquid epoxy resin composition is impregnated into a fibrous base material, a solid epoxy resin Sheets obtained by dissolving the composition in a solvent and impregnating the fibrous base material, and sheets obtained by heating and melting the solid epoxy resin composition and impregnating the fibrous base material are known. However, a sheet impregnated with a liquid epoxy resin composition or a sheet impregnated by dissolving a solid epoxy resin composition in a solvent is impregnated with the epoxy resin and the curing agent because they are completely compatible. There was a problem with stability. There is also a problem in using a solvent from the viewpoint of safety and health. On the other hand, a sheet obtained by heating and melting a solid epoxy resin composition and impregnating a fibrous base material is a sheet impregnated with a liquid epoxy resin composition or a solid epoxy resin composition dissolved in a solvent and impregnated. Compared with the conventional sheet, the storage stability is improved, but it is not sufficient, and there is a problem in manufacturing such that a high pressure is required to impregnate the fibrous base material. A sheet in which a dry mixture of a crystalline epoxy resin and a curing agent is sprayed on a fibrous base material, heated and melted to impregnate the fibrous base material is also known as an improved impregnating property to the fibrous base material ( JP-A-62-240375
issue). However, this sheet is not yet satisfactory in terms of its storage stability.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to provide an epoxy resin composition-impregnated sheet having good storage stability and excellent use characteristics. .

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention. That is, according to the present invention, a sheet in which two types of epoxy resin compositions A and B are each impregnated in a fibrous base material in a layered manner, wherein the composition A comprises a crystalline epoxy resin A and a curing agent A Wherein the composition B comprises a non-crystalline epoxy resin B and a curing agent B thereof.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The fibrous base material of the sheet impregnated with the epoxy resin composition of the present invention (hereinafter, also simply referred to as a sheet) includes a nonwoven fabric or woven fabric made of fibers such as organic fibers, glass fibers and ceramic fibers. A knitted cloth or the like is used. In this case, the resin (organic polymer) constituting the organic fiber can be any of various conventionally known thermoplastic resins, and the fibrous base material composed of the organic fiber is obtained by thermosetting the epoxy resin composition impregnated sheet. At the time of the curing, the cured product may remain as a base material or may be melted. As the organic fiber remaining in the cured product as a substrate, it is particularly preferable to use a fiber made of polyamide or polyester from the viewpoint of price, quality stability, workability and the like. From the viewpoint of heat resistance, it is preferable to use wholly aromatic polyamide. In the present invention, as the fibrous base material, a nonwoven fabric is preferably used, but from the viewpoint of impregnation of the epoxy resin composition, the thickness is 0.05 to 1.5.
mm, preferably 0.1-1.0 mm, its weight is 20
２００200 g / m ² , preferably 30-120 g / m ² . The nonwoven fabric having such a configuration has excellent workability when impregnating the solid epoxy resin composition in a molten state or a state close to the molten state, and also has excellent impregnation retention of the impregnated composition. Things.

In the present invention, two types of epoxy resin compositions A and B are used. Composition A of one of them
Contains a crystalline epoxy resin A and the other composition B
Contains an amorphous epoxy resin B. Composition A comprises
When this is analyzed by a differential scanning calorimeter (DSC) (heating rate: 10 ° C./min), the chart shows an endothermic peak based on the melting of the crystalline epoxy resin. The composition A used in the present invention will be described in detail.
Contains at least one high-melting crystalline epoxy resin A. One example of such a high-melting crystalline epoxy resin A is one containing a dihydric phenol diglycidyl ether-based crystalline epoxy resin having a melting point of 115 ° C. or more and having a steric hindrance group at the position adjacent to the glycidyl ether group. It is. Such a high-melting crystalline epoxy resin A includes those represented by the following general formula (1).

Embedded image In the above formula, R ¹ represents a sterically hindered group, R ² represents a lower alkyl group or a halogen atom, G represents a glycidyl group,
m shows the number of 0-3, n shows the number of 0 or 1. Sterically hindered groups include an iso-propyl group, an iso-butyl group,
An iso-alkyl group having 3 to 6 carbon atoms such as an iso-amyl group, an iso-hexyl group, a tert-butyl group, a tert-amyl group, a tert-hexyl group, and a C4 to C6 group
Tert-alkyl group and the like. Examples of the lower alkyl group include an alkyl group having 1 to 6 carbon atoms, for example, methyl, ethyl, propyl, butyl, amyl, hexyl, and the like. The lower alkyl group may be the sterically hindered group. . Examples of the halogen atom include chlorine and bromine.

The high melting point crystalline epoxy resin A represented by the general formula (1) is disclosed in, for example, JP-A-6-14.
No. 5,293, JP-A-6-298902 and the like. Other examples of the high melting point crystalline epoxy resin A include those represented by the following general formula (2).

Embedded image In the above formula, R ¹ , R ² , G and m have the same meaning as described above. Further, other examples of the high melting crystalline epoxy resin A include those represented by the following general formula (3).

Embedded image In the above formula, G and m have the same meaning as described above, and R ³ represents a lower alkyl group or a halogen atom. Still other examples of the high melting crystalline epoxy resin A include 2,7-dihydroxyphenanthrene-diglycidyl ether and 1,1
Examples thereof include 5-dihydroxynaphthalene-diglycidyl ether and stilbene-based epoxy resins such as 4,4'-dihydroxy-3,3 ', 5,5'-tetramethylstilbene. The high melting point crystalline epoxy resin A used in the present invention has a melting point of 115 ° C. or more, preferably 1 ° C. or more.
40-180 ° C.

The composition A used in the present invention preferably contains a high-melting crystalline hardener A. High melting crystalline hardener A
As bisphenol compounds such as bisphenol A (melting point 157 ° C.), bisphenol F, bisphenol S (melting point 245 ° C.), and tetrabromobisphenol A (melting point 180 ° C.); 5 (2,5-dioxotetrahydrofurolyl) -3 -Methyl-3-cyclohexene-1,2-
Dicarboxylic anhydride (“Epiclon B-4400”, manufactured by Dainippon Ink, melting point 165 ° C.), nadic anhydride,
Acid anhydrides such as trimellitic anhydride (melting point 165 ° C.), derivatives of trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic anhydride; diamino compounds such as diaminodiphenyl ether and diaminodiphenyl sulfone; Organic acid hydrazide, dicyandiamide and the like can be mentioned.

Among the high melting crystalline hardeners A, bisphenol compounds are hardeners which can be preferably applied to the present invention. Since the bisphenol compound has a high melting point and an excellent low melt viscosity, it can be used in combination with the high melting point crystalline epoxy resin A to form a solid with excellent tackiness and a low melt viscosity. An epoxy resin composition is provided. Among the high-melting crystalline hardeners A, trimellitic anhydride and trimellitic anhydride derivatives are hardening agents that can be preferably applied to the present invention. In this case, the trimellitic anhydride derivative means a compound in which a free carboxyl group bonded to trimellitic anhydride has reacted with another reactive compound. Such reactive compounds include monohydric alcohols that give fatty acid esters, alcohols such as glycols (ethylene glycol and propylene glycol) and triols (such as glycerin), phenols that give aromatic esters, alkylphenols, and polyhydric phenols. Is mentioned. Surprisingly, such trimellitic anhydride and trimellitic anhydride derivatives are:
It has been found that it reacts at a high rate with the high-melting crystalline epoxy resin A having low curing reactivity represented by the general formulas (1) and (2), and its gelation time becomes very short. The content of this trimellitic anhydride and / or derivative thereof is:
At least 5% by weight, preferably 10-1
00% by weight. In the present invention, trimellitic anhydride and / or a derivative thereof can be preferably used as a mixture with a bisphenol compound. In this case, the proportion of trimellitic anhydride and / or a derivative thereof is 20 to 60% by weight, preferably 3%, based on the total weight of both.
0 to 50% by weight.

The high-melting crystalline hardener A used in the present invention has a melting point of 115 ° C. or higher, preferably 140 to 1 ° C.
80 ° C. Such a high-melting crystalline curing agent A gives a solid epoxy resin composition having a high fluidity during melting.

The present invention preferably relates to the use of the high-melting crystalline epoxy resin A and the high-melting crystalline hardener A, which are at least higher than the melting point of the crystalline substance having the lowest melting point. 30 ° C lower, preferably about 35-100 ° C lower, more preferably 40-8
A low-melting epoxy resin and / or a curing agent having a melting point or a softening start point lower by about 0 ° C. is used. These epoxy resins and curing agents may be crystalline or non-crystalline.

Among the high melting point crystalline epoxy resins A used in the present invention, those having a steric hindrance group at the position adjacent to the glycidyl ether group have low curing reactivity.
Such a low curing reactive high melting point crystalline epoxy resin A
Is preferably used in the form of a mixture with a low-melting epoxy resin (hereinafter also referred to as epoxy resin A ′) having a fast curing reaction. As such a quick-curing epoxy resin A ', a normal epoxy resin which does not have a steric hindrance group at the position adjacent to the glycidyl ether group and which is solid at room temperature is used. Such quick-curing epoxy resin A 'includes general-purpose crystalline epoxy resins and non-crystalline epoxy resins. As the crystalline epoxy resin, those having a melting point lower than 115 ° C., for example, tetramethylbiphenol diglycidyl ether (melting point 105 ° C.), tetramethylbisphenol A diglycidyl ether (“ESLV-80X
Y ”, manufactured by Nippon Steel Chemical Co., Ltd., melting point 78 ° C.), bis (4-hydroxyphenyl) ether diglycidyl ether (“ E
SLV-80DE ", manufactured by Nippon Steel Chemical Co., Ltd., melting point 79 ° C),
formula

Embedded image (Wherein, G represents a glycidyl group) epoxy resin (“ESLV-90CR”, manufactured by Nippon Steel Chemical Co., Ltd., melting point 89 ° C.), triglycidyl isocyanate (melting point 100 ° C.), and the like. As a fast-curing non-crystalline epoxy resin, bisphenol A type epoxy resin,
Bisphenol F epoxy resin, biphenyl epoxy resin, 1,1,2,2-tetrakis (glycidyloxyphenyl) ethane, novolak epoxy resin such as phenol novolak type, alkylphenol novolak type, bisphenol A novolak type, and cyclopentadiene・ Phenol type epoxy resin (“DCE40
0 ", manufactured by Sanyo Kokusaku Pulp Co., Ltd., with a softening point of 65 ° C) and a trifunctional aromatic epoxy resin [" Epicoat YL933 "
(Softening point 60 ° C, manufactured by Yuka Shell Epoxy Co., Ltd.), “VG3
101 "(manufactured by Mitsui Petrochemical, softening point 61 ° C), etc.], 4
Functional aromatic epoxy resin ("Epicoat 1031"
S ", manufactured by Yuka Shell Epoxy, softening point 92 ° C, etc.), 4
Functional or higher polyfunctional aromatic epoxy resin (“Epicoat 1032”, manufactured by Yuka Shell Epoxy Co., softening point 92 ° C.)
Etc.). In the present invention, trifunctional or more, especially 4
It is preferable to use a multifunctional or higher functional epoxy resin.

When a low-curing high-melting crystalline epoxy resin A having a low curing reactivity is mixed with a fast-curing epoxy resin A ′, the curing reactivity of the mixed epoxy resin is improved, and the gelation time is shortened. Among the fast-curing epoxy resins A ', in particular, three or more glycidyl ether groups in the molecule, particularly 4
The use of aromatic epoxy resin containing more than one is preferred,
By mixing this with the high-melting crystalline epoxy resin A having low curing reactivity, a mixed epoxy resin having high curing reactivity can be obtained. The content of the high melting point crystalline epoxy resin A in all epoxy resins is at least 55% by weight.
If it is less than this, the low melting viscosity of the high melting crystalline epoxy resin A will be impaired, and the cooling and solidification rate of the mixture after mixing in the molten state will be slow, so that pulverization is possible. It takes a long time to become a solid. From the viewpoint of low melt viscosity, improvement in curing reactivity, and cooling solidification, the content of the high melting crystalline epoxy resin A in all epoxy resins is 55 to 95% by weight, preferably 65 to 95% by weight. % By weight, more preferably 70%
~ 95% by weight. The mixing ratio of the high melting crystalline epoxy resin A is adjusted so that the mixed epoxy resin exhibits a solid state without tackiness (tackiness) at room temperature. The minimum content for that depends on the type of epoxy resin mixed with the high melting crystalline epoxy resin A, but is usually 55% by weight or more.

The low-melting curing agent A 'used in the present invention comprises:
It can be an amorphous hardener. Examples of such non-crystalline hardeners include those which show a solid state at ordinary temperature, such as phenol novolak type resin ("Tamanol # 754", manufactured by Arakawa Chemical Co., softening point 100 ° C), and orthocresol novolak type. Resin (“OCN90”, manufactured by Nippon Kayaku Co., softening point 120 ° C.), bisphenol A novolak type resin (“Epicure YLH-129”, manufactured by Yuka Shell Epoxy, softening point 115 ° C.), aminopolyamide resin, polysulfide resin And the like. The content of the high-melting crystalline hardener A in all hardeners should be at least 5% by weight, preferably 50 to 100% by weight.

The composition A of the present invention can contain a curing accelerator, if necessary. Examples of the curing accelerator include conventionally known ones, for example, tertiary amines, quaternary ammonium salts, phosphine compounds, phosphonium salts, imidazole compounds and the like. Composition A of the present invention can contain conventional auxiliary ingredients. Such auxiliary components include, for example, organic or inorganic fillers, flame retardants,
A silane coupling agent, a coloring agent, a release agent and the like are included.

The epoxy resin composition A containing the crystalline epoxy resin A according to the present invention can be prepared by a dry blending method, a pressure bonding method,
Although it can be produced by various conventionally known methods such as a melt blending method, a melt blending method is preferably employed. To produce the composition A by a melt blending method,
First, (i) a high-melting crystalline epoxy resin, (ii) a low-melting epoxy resin and / or a curing agent as essential components, and if necessary, a high-melting crystalline curing agent or a curing accelerator,
A mixture containing auxiliary components such as a filler is formed by a dry blending method. In this case, the curing agent and the curing accelerator can be mixed in advance, and when two or more epoxy resins are used, those epoxy resins can be mixed in advance. Further, when two or more curing agents are used, those curing agents can be mixed in advance. As a mixing method in this case,
A melt blending method can be employed. Next, the mixture is melt blended. In this case, at least a part of the high-melting crystalline epoxy resin contained in the mixture and / or at least a part of the high-melting crystalline hardener used as needed remain unmelted and solid. Do so. The heating temperature in this case is a temperature that is at least 30 ° C. lower than the melting point of the highest melting crystalline substance having the lowest melting point, preferably a temperature that is about 35 to 100 ° C. lower, and more preferably a temperature that is about 40 to 80 ° C. lower. And the temperature at which the low-temperature fusible material is substantially completely melted. Next, the partially melted mixture obtained as described above is cooled and solidified, and the solidified material is pulverized. The powder thus obtained is subjected to a thermal analysis by a differential scanning calorimeter (DSC) (heating rate: 10 ° C./min).
Then, in the chart, an endothermic peak based on the melting of the high-melting crystalline epoxy resin A and / or an endothermic peak based on the melting when the high-melting crystalline epoxy resin is included. That is, the epoxy resin composition A obtained as described above contains a crystalline substance having a high melting point, and has a great feature that its melt viscosity is low and its fluidity during melting is high.

In the epoxy resin composition A obtained by the melt blending method as described above, each component is easily bonded even when an external force such as a stirring force or a vibration force is applied, since each component is firmly bound. Does not peel off. Further, since this composition contains the unmelted high-melting crystalline epoxy resin A, it has excellent storage stability. Therefore, a cured product obtained by heat-curing the cured product has excellent uniformity of properties and excellent performance. Since the viscosity of the composition A at the time of melting is very low, the composition A is excellent in impregnation (penetration) into minute voids. In addition, since the surface of the solid composition is non-tacky (has no surface tackiness), for example, the particles do not stick to each other, and are extremely excellent in handling and workability. is there.

Next, the epoxy resin composition B containing the non-crystalline epoxy resin B used in the present invention will be described in detail. As the composition B, various conventionally known epoxy resin compositions can be used. As the epoxy resin B in the composition B, a bisphenol type non-crystalline epoxy resin is preferably used. The softening point is not particularly limited, and may be generally 65 ° C. or higher, preferably 80 ° C. or higher. The curing agent B used in the composition B is
It may be crystalline or non-crystalline. The melting point or softening point is not particularly limited, and is usually 65 ° C. or higher, preferably 80 ° C. or higher. The composition B used in the present invention can contain a curing accelerator, if necessary. Examples of the curing accelerator include conventionally known ones, for example, tertiary amines, quaternary ammonium salts, phosphine compounds, phosphonium salts, imidazole compounds and the like. Composition B used in the present invention
Can contain conventional auxiliary ingredients. Such auxiliary components include, for example, organic or inorganic fillers,
It includes flame retardants, silane coupling agents, coloring agents, release agents and the like. The composition B used in the present invention is manufactured by a melt blending method, a dry blending method, a pressure bonding method, or the like, which is conventionally generally used, but is generally manufactured by a melt blending method.

In the two compositions A and B used in the present invention, the curing accelerator used on the one hand is preferably selected in relation to the curing agent used on the other. That is, it is preferable to use one that promotes the curing action of the curing agent. For example, when a phenol compound is used as a curing agent for the epoxy resin composition A, a curing accelerator B for the epoxy resin composition B is used.
Is preferably used, and when an aromatic diamino compound is used as the curing agent A of the epoxy resin composition A, para-toluene is used as the curing accelerator B of the epoxy resin composition B. It is preferable to use at least one selected from low-molecular-weight acids such as sulfonic acid, adipic acid, and salicylic acid, and low-molecular-weight phenol compounds such as phenol, gresol, and bisphenol A. The curing agent A for the epoxy resin composition A is preferably used. When an acid anhydride is used, the epoxy resin composition B
It is preferable to use one or more selected from imidazole compounds, dicyandiamide (DICY), and tertiary amines as the curing accelerator B. Thus, by selecting a combination of the curing agent of one epoxy resin composition and the curing accelerator of the other epoxy resin composition, the curing speed of the sheet of the present invention is accelerated.

To manufacture the sheet of the present invention, for example,
First, the epoxy resin composition A is sprayed on the surface of the fibrous base material in a uniform layer, and then the epoxy resin composition B is sprayed on the surface of the fibrous base material in a uniform layer.
In a molten state or a state close to a molten state. Thereby, the compositions A and B are impregnated and held in the fibrous base material. Next, the fibrous base material impregnated with the compositions A and B is
This is cooled and the liquid composition solidifies. Thus, the impregnated layer composed of the composition A and the impregnated layer composed of the composition B are formed in the fibrous base material. The impregnation amount of the whole composition to the fibrous base material is 40 to 80 as the fibrous base material.
g / m ² when using a nonwoven fabric of 20 to 600 g
/ M ² . The use ratio of the compositions A and B is 80:20 to 2 by weight ratio A: B of the composition A to the composition B.
0:80, preferably 60:40 to 40:60.
In the above-described sheet manufacturing method, the heating temperature of each composition is preferably a temperature at which at least one epoxy resin and / or curing agent exists in an unmelted state. By using such a heating temperature, the solidified material in the fibrous base material has significantly improved storage stability.

In order to use the sheet of the present invention, the sheet is overlaid on the surface of the object to be treated such as a wound coil so that the composition A impregnated therein is in contact with the sheet. Heat. By this heating, the composition impregnated in the sheet is melted and eluted from the sheet and migrates to the surface of the object to be treated. In the case of the sheet of the present invention, first, the melt of the composition A is applied to the surface of the object to be treated. And then the melt of composition B. In this case, since the composition A has excellent fluidity at the time of melting, it is smoothly impregnated into the object to be treated. The composition B has a lower impregnating property than the composition A, but forms a coating having a large surface covering property and a high mechanical strength on the coating of the composition A.

[0022]

The epoxy resin composition-impregnated sheet of the present invention has almost no voids and uneven heating because the epoxy resin composition A and the epoxy resin composition B are used in combination.
Excellent fast curing, storage stability, impregnation, no tack,
It has excellent adhesiveness and electrical insulation properties of the cured product, and is suitable as a sheet for insulating and fixing electric and electronic parts, a prepreg sheet, and the like. The sheet impregnated with the epoxy resin composition of the present invention has both properties of a sheet impregnated with only the epoxy resin composition A and a sheet impregnated with only the epoxy resin composition B. By setting the combination of the curing agent of the resin composition and the curing accelerator of the other epoxy resin composition to the specific combination described above, the gelation time of the epoxy resin composition-impregnated sheet of the present invention can be reduced by the epoxy resin composition. The gelation time of a sheet impregnated with only the product A and the gelation time of a sheet impregnated with only the epoxy resin composition B can be shortened.

[0023]

Next, the present invention will be described in more detail with reference to examples. The parts shown below are parts by weight.

Reference Example 1 Epotote YDC-1312 (2,5-di-t-butylhydroquinone diglycidyl ether, manufactured by Toto Kasei Co., Ltd.)
(Epoxy equivalent: 175, melting point: 145 ° C) and the epoxy resin shown in Table 1 were melt-blended, and the mixture was cooled (14 ° C).
Solidified. Table 1 shows the properties of the solidified product thus obtained and the cooling solidification time. In this case, the cooling solidification time refers to a time during which the mixture is mixed in a molten state and the cooled (14 ° C.) mixture solidifies to a hardness that can be finely pulverized. The symbols shown in Table 1 indicate the following contents. Epotote YD-7011: bisphenol A type epoxy resin (non-crystalline), epoxy equivalent: 475, softening point: 65 ° C, manufactured by Toto Kasei Co., Ltd. Epotote YDCN-701: cresol novolak type epoxy resin (non-crystalline), epoxy equivalent: 215, softening point: 65 ° C., manufactured by Toto Kasei EOCN-103: cresol novolak type epoxy resin (non-crystalline), epoxy equivalent: 220, softening point: 82
℃, Nippon Kayaku Co., Ltd. Epicoat YL-6350: tetrabromobisphenol A diglycidyl ether (crystalline), epoxy equivalent:
335, melting point 115 ° C, manufactured by Yuka Shell Epoxy

[0025]

[Table 1]

As can be seen from the results shown in Table 1, when a high-melting crystalline epoxy resin A having a low curing reactivity and another fast-curing epoxy resin A 'are melt-mixed and solidified by cooling, the solidified resin is cooled and solidified. The time is fast, and the obtained solid is a crystalline mixed epoxy resin having a sufficiently high melting point and a non-adhesive surface and excellent handleability. Therefore, such a crystalline mixed epoxy resin gives a powder composition having good low viscosity.

COMPARATIVE REFERENCE EXAMPLE 1 70 parts by weight of Epicoat YX-4000 (tetramethylbiphenol diglycidyl ether, melting point: 105 ° C.) and 30 parts by weight of Epicoat YD-7011 were melt-blended, and the mixture was allowed to stand at room temperature and solidified by cooling. As a result, the cooling and solidification required a long time of 48 hours or more, and the surface of the obtained solidified material showed tackiness. Therefore, this solidified product is unsuitable as a raw material epoxy resin for forming a powder composition.

The determination as to whether or not the powder surface was non-tacky was performed by the following method. Temperature 2
In an atmosphere of 5 ° C. and a humidity of 70% RH, 50 g of the powder passing through a 60-mesh sieve was placed in a cylindrical container having an inner diameter of 5 cm, and left under a load of ² g / cm ² for 3 hours. Next, the powder was taken out of the cylindrical container, and the powder was placed on a low-tapped shaker φ200A manufactured by Iida Manufacturing Co., Ltd. with a mesh size of 60 mesh attached to a sieve at a rotation speed of 290 times / minute and an impulse speed of 165 times / minute. Sift and shake for 30 minutes.
If 95% by weight or more of the powder passes through a 60-mesh sieve due to the shaking, the powder is determined to be non-tacky. Otherwise, the powder is not non-tacky (adhesive There is).

Composition A Preparation Example 1 A powder composition having the composition shown in Table 2 was prepared by a melt blending method (temperature: 80 ° C.), and the gel time was evaluated. Table 2 shows the results. Gel time is the gel time at 150 ° C
Measured according to SC 2104. The symbols shown in Table 1 mean the following contents. BPA: Bisphenol A (melting point: 157 ° C.) THPA: Tetrahydrophthalic anhydride (melting point: 101 ° C.) YLH-129: Bisphenol A novolak type resin (“Epicure YLH 129”, softening point: 115 ° C., manufactured by Yuka Shell Epoxy) DAM: Diaminodiphenylmethane (melting point 90 ° C.) TMA: trimellitic anhydride (melting point 165 ° C.) TBA: tetrabromobisphenol A (melting point 180 ° C.) TPP: triphenylphosphine 2MZ-A: 2,4-diamino-6-6 [2 -Methylimidazolyl (1)]-ethyl S-triazine

[0030]

[Table 2] * 1 Epoxy resin B was previously melt-blended with epoxy resin A and epoxy resin D at a mixing weight ratio of 85/15. * 2 Shows a comparative example.

As can be seen from the results shown in Table 2, as the epoxy resin, only a high-melting crystalline epoxy resin A having a low curing reactivity and containing no fast-curing epoxy resin was used, and TMA was used as a curing agent. In the case of using no composition (composition No. 9), it can be seen that the curing reactivity of the composition was very poor. On the other hand, as a curing agent, TMA
When a composition containing (No. 3 to No. 5) is used
Shows that the composition has a very good curing reactivity and is rapidly cured by heating. Moreover, in this case, even when only the high melting point crystalline epoxy resin A having poor curing reactivity is used (composition No. 3), the curing speed of the composition is high.

Composition A Preparation Example 2 High melting point crystalline epoxy resin (YDC-1312) 85
Part, low temperature melting epoxy resin (ECON-103) 15
Part, 22 parts of high melting crystalline hardener (BPA), 42 parts of low temperature melting hardener (YLH-129), 1.0 part of imidazole / epoxy adduct (P-200) and acrylic ester oligomer (XK-21) After 0.5 part was uniformly mixed by a melt blending method (temperature: 80 ° C.), the obtained partially molten mixture was cooled and solidified to room temperature, and the obtained solid was pulverized. Since the pulverized material contains a crystalline substance, the pulverized material has a low melt viscosity and excellent fluidity during melting.

Preparation Example 3 of Composition A In Preparation Example 2 of Composition A, as the high melting point epoxy resin, 4,4'-dihydroxydiphenylsulfone diglycidyl ether (EBPS-200) (melting point: 165)
Experiment was performed in the same manner except that (° C) was used.

Composition B Preparation Example 1 Bisphenol A type epoxy resin (Epicoat 100
4, epoxy equivalent: 900, softening point 89 ° C, 100 parts by Yuka Shell Epoxy Co., Ltd., heavy calcium carbonate (KC-
30A) 10 parts, light calcium carbonate (TP-111)
10 parts, acrylate oligomer (XK-21)
0.5 part, 10 parts of triphenylphosphine (TPP) and 0.5 part of 2MZ-A were mixed by heating at 80 ° C. by a melt blending method, then cooled and solidified to room temperature, and pulverized.

Example 1 Polyester nonwoven fabric ("JH-1007", manufactured by Japan Vilene Co., Ltd .; weight: 68.6 g / m ² , thickness: 0.13 m)
m), 8 parts of the melt-blended composition A shown in Table 3
After spraying uniformly in a layer at a rate of 0 g / m ² , the molten blend composition B was sprayed uniformly thereon at a rate of 80 g / m ² . Next, the nonwoven fabric was impregnated in an oven set at 130 ° C. with at least a part of each composition unmelted, immediately cooled to 14 ° C. and solidified to obtain Sheet I.

[0036]

[Table 3]

Comparative Example 1 A sheet II was obtained in the same manner as in Example 1, except that only the composition A shown in Table 3 was used at 160 g / m ² as the epoxy resin composition.

Comparative Example 2 A sheet III was obtained in the same manner as in Example 1, except that only the composition B in Table 3 was used as the epoxy resin composition at a rate of 160 g / m ² .

Comparative Example 3 A liquid bisphenol A type epoxy resin ("Epicoat 8
28 ", epoxy equivalent 190, 100 parts of Yuka Shell Epoxy Co., Ltd., dicyandiamide (" Dicy # 1
5 ", 8 parts of Yuka Shell Epoxy Co., Ltd.) and 0.5 parts of 2-methylimidazole (2MZ-P, manufactured by Shikoku Kasei Co., Ltd.) were dissolved in 108.5 parts of methyl cellosolve (boiling point: 124.5 ° C.). This solution is applied to a polyester nonwoven fabric (“JH-100”).
7 ", a basis weight of 68.6 g / m ² , a thickness of 0.13 mm, manufactured by Japan Vilene Co., Ltd.) at a rate of 320 g / m ² , impregnated, and volatilize the solvent in an oven set at 130 ° C. To obtain a sheet IV.

Comparative Example 4 Bisphenol A type epoxy resin ("Epicoat 100")
4 ", epoxy equivalent 900, Yuka Shell Epoxy)
50 parts, liquid bisphenol A type epoxy resin (“Epicoat 828”, epoxy equivalent 190, manufactured by Yuka Shell Epoxy) 50 parts, dicyandiamide (“Dicy # 1”)
5 ", 4.8 parts of Yuka Shell Epoxy Co., Ltd.) and 0.5 part of 2-methylimidazole (2MZ-P, Shikoku Chemicals) were dissolved in 106.5 parts of methyl cellosolve (boiling point: 124.5 ° C.). . This solution is applied to a polyester nonwoven fabric (“JH-10”).
07 ", a basis weight of 68.6 g / m ² , a thickness of 0.13 mm,
Sheet V was obtained by uniformly coating and impregnating 320 g / m < ² > with Nippon Vilene Co., Ltd., and evaporating the solvent in an oven set at 130 [deg.] C.

The storage stability, impregnation, tackiness and adhesion of the sheets of Examples 1 to 4 were evaluated by the following methods. Table 4 shows the results. (Storage Stability) The gelation time at 150 ° C. of the sheet immediately after preparation is A, and the gelation time at 150 ° C. after storage of this sheet at 40 ° C. for 21 days is B, and the storage stability of the sheet is as follows. Evaluation was based on criteria. B / A = 0.75 or more: ○ B / A = 0.65 to less than 0.75: Δ B / A = 0.65 or less: × (impregnating property) Polyester nonwoven fabric cut to 50 × 50 mm (“JH- 1007 ", a basis weight of 68.6 g / m ² , a thickness of 0.13 mm, manufactured by Nippon Vilene Co., Ltd.), a 25 mm-diameter cut sheet, and a 50 × 50 mm cut polyester nonwoven fabric thereon. (“JH-1007”, weight: 68.6 g / m ² , thickness: 0.13 mm, manufactured by Japan Vilene Co., Ltd.). Next, this is placed on a preheated 60 × 60 × 3 mm steel plate in an oven at 150 ° C., and a weight of 1 kg is placed thereon so as to uniformly load the whole, and heated for 30 minutes. Is melted and impregnated into the nonwoven fabric,
Cool. The number of nonwoven fabrics impregnated with the composition was examined, and the impregnation property was evaluated based on the following criteria. 6 sheets or more: ○ 4-5 sheets: △ 0-3 sheets: ×

(Tackiness) Two 20 × 20 mm cut sheets were stacked, sandwiched between two smooth glass plates of 20 × 80 × 1 mm, and a 1 kg weight was placed thereon.
The adhesion between the two sheets after standing at 10 ° C. for 10 minutes was evaluated according to the following criteria. Hardly adhered and can be easily peeled off: ○ Closely adhered but relatively easily peeled off: 密 着 Strongly adhered and difficult to peel off: × (Adhesiveness) Sheet is adhered to JIS K6850 according to JIS K6850. Was used to measure the shear adhesion, and the adhesion was evaluated according to the following criteria. 2.5 kg / mm ² or more: ○ 1.5 kg / mm ² or more and less than 2.5 kg / mm ² : △ Less than 1.5 kg / mm ² : ×

[0043]

[Table 4]

Claims (5)

[Claims] 1. A sheet in which two types of epoxy resin compositions A and B are each impregnated into a fibrous base material in a layered manner, the composition A comprising a crystalline epoxy resin A and a curing agent A thereof.
Wherein the composition B comprises a non-crystalline epoxy resin B and a curing agent B thereof. 2. The sheet according to claim 1, wherein said crystalline epoxy resin A is 2,5-di-tert-butylhydroquinone diglycidyl ether. 3. The curing agent A is a bisphenol compound,
3. The composition according to claim 1, which is at least one selected from trimellitic anhydride and trimellitic anhydride derivatives.
Sheet. 4. The epoxy resin composition according to claim 1, wherein the epoxy resin composition A comprises an epoxy resin having no steric hindrance group at the position adjacent to the glycidyl ether group and / or an epoxy resin having three or more glycidyl ether groups. Any sheet. 5. The sheet according to claim 4, wherein the epoxy resin having three or more glycidyl ether groups is a novolak type epoxy resin.