JP2001335651A - Epoxy resin composition for impregnation of organic fiber substrate, and prepreg, laminated sheet and printed wiring board using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition with non-halogen, capable of satisfying flame retardance and thermostability and suitable for a printed wiring board of organic fiber substrate. SOLUTION: The epoxy resin (a bisphenol A type epoxy resin and a poly functional epoxy resin having three or more functional groups) composition contains a phosphorus compound and a resin having a nitrogen atom in its molecular structure. In this composition, the content of the bisphenol A type epoxy resin is 5 to 20 mass %, the total of phosphorus and nitrogen in a resin solid content is 5.5 to 7.7 mass %, and the mass ratio (phosphine/nitrogen) of phosphorus to nitrogen in the above resin solid content is 0.2/1 to 1/1, preferably 0.3/1 to 0.6/1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a flame-retardant epoxy resin composition for impregnating an organic fiber base material. In addition, the present invention relates to a prepreg, a laminate, a metal foil-clad laminate, and a printed wiring board using the epoxy resin composition.

[0002]

2. Description of the Related Art An epoxy resin printed wiring board to be incorporated in an electronic device is required to have safety such as being difficult to burn and difficult to spread. Therefore, a brominated epoxy resin or a bromine-added phenol novolak resin is used as a curing agent for the epoxy resin to impart flame retardancy.
However, when halogen-containing materials such as bromine and chlorine are used at high temperatures for a long time, there is a concern that halides may be dissociated.
When the halogen-containing material is incinerated, there is a concern that harmful halides are generated. In recent years, from the viewpoint of environmental safety, the direction of imparting non-halogen flame retardancy is changing.
Phosphorus compounds have attracted attention as flame retardants instead of halogen compounds. Most of the phosphorus compound is a phosphate ester compound having a low melting point (80 to 100 ° C.), so that it is easily thermally decomposed at a high temperature during combustion. The carbonized film of polyphosphoric acid generated by thermal decomposition shields the resin from oxygen and heat, thereby exhibiting a flame retardant effect.

However, printed wiring boards and multilayer printed wiring boards are exposed to high temperatures during soldering for component mounting and in a reflow process at about 270 ° C. If a large amount of a low-melting phosphorus compound is added in order to impart flame retardancy, the phosphorus compound is thermally decomposed in the above step, and blistering occurs at the interface between the printed wiring and the resin. Therefore, when a phosphorus compound is added to impart flame retardancy to a printed wiring board or a multilayer printed wiring board, it is also required that the addition does not cause a decrease in heat resistance.

[0004]

An epoxy resin printed wiring board using a glass fiber woven fabric or a glass fiber non-woven fabric as a base material of an insulating layer has been frequently used.
Flame retardancy can be imparted only by adding a small amount of a phosphorus compound.
This is because there are many non-combustible glass fibers. But,
The organic fiber-based epoxy resin printed wiring board requires special measures for the resin composition for imparting flame retardancy with no halogen, since the substrate itself is easily flammable. Moreover, as described above, in a printed wiring board or multilayer printed wiring, even if flame retardancy can be imparted by adding a large amount of a phosphorus compound, it is difficult to satisfy heat resistance.

[0005] Accordingly, an object of the present invention is to provide an organic fiber-based printed wiring board which imparts flame-retardant properties without halogen while reducing the amount of a phosphorus compound added, and also satisfies heat resistance. It is to provide an epoxy resin composition. Another object of the present invention is to provide a prepreg, a laminate or a metal foil-clad laminate, a printed wiring board or a multilayer printed wiring board of an organic fiber substrate to which the epoxy resin composition is applied. Still another object of the present invention is to secure a sufficient peeling strength of a metal foil (printed wiring) in addition to the above-mentioned problems.

[0006]

In order to solve the above problems, the first epoxy resin composition for impregnating an organic fiber substrate according to the present invention comprises a bisphenol A type epoxy resin as a bifunctional epoxy resin and a trifunctional epoxy resin. The above polyfunctional epoxy resin, and further, a phosphorus compound and a resin having a nitrogen atom in the molecular structure are included. The content of bisphenol A type epoxy resin in the resin solid content is set to 20% by mass or less, and the total content of phosphorus and nitrogen in the resin solid content is set to 5.5 to 7.7% by mass.
And the mass ratio of phosphorus and nitrogen contained (phosphorus / nitrogen)
From 0.2 / 1 to 1/1, preferably from 0.3 / 1 to 0.1.
The feature is that it is 6/1. Of course, it is a substantially non-halogen resin composition.

The second epoxy resin composition for impregnating an organic fiber substrate according to the present invention comprises a bisphenol F type epoxy resin as a bifunctional epoxy resin, a trifunctional or higher polyfunctional epoxy resin, and Includes compounds and resins having a nitrogen atom in the molecular structure. The content of bisphenol F type epoxy resin in the resin solid content is 30% by mass or less, and the total content of phosphorus and nitrogen in the resin solid content is 2 to 7.7% by mass. And the mass ratio of phosphorus and nitrogen (phosphorus / nitrogen) contained is 0.2 / 1 to 1/1, preferably 0.3
/ 1 to 0.6 / 1. Of course, it is a substantially non-halogen resin composition.

[0008] The reaction of forming a carbonized film by a phosphorus compound is as follows.
It is known that it is promoted by using a resin having a nitrogen atom in the molecular structure in combination (Hitoshi Nishizawa, "Flame Retardation of Polymer", pp. 34-38, Taiseisha Co., Ltd. 1).
989). For an epoxy resin composition applied to an organic fiber-based printed wiring board, good flame retardancy can be imparted without halogen for the first time by using the above composition (particularly the composition of phosphorus and nitrogen). ,
Moreover, there is a remarkable effect that the heat resistance is not reduced. There is a concern that the cured product becomes too brittle due to the reaction between the polyfunctional epoxy resin and the curing agent, or the elastic modulus of the cured product decreases due to the addition of the phosphorus compound, and the peel strength of the metal foil (printed wiring) decreases. However, the incorporation of the above bifunctional epoxy resin makes the molecular weight distribution of the epoxy resin composition uniform and contributes to securing good peel strength of the metal foil (printed wiring). From the viewpoint of ensuring flame retardancy, the bifunctional epoxy resin is blended in an amount of 20% by mass or less in the first resin composition and 30% by mass in the second resin composition.
Do the following.

Bifunctional epoxy resin is bisphenol A
Bisphenol S epoxy resin as well as bisphenol F epoxy resin can be selected in addition to bisphenol F epoxy resin. It is possible to increase the bifunctional epoxy resin content in the resin solids to at least 5% by mass to draw metal foil (printed wiring). It is more preferable in terms of securing the peel strength. The selection of a bisphenol F type epoxy resin as the bifunctional epoxy resin is more preferable from the viewpoint of ensuring flame retardancy, and more preferably, the epoxy equivalent is set to 150 to 2300. When a bisphenol F type epoxy resin having a high epoxy equivalent is blended, the elasticity of the cured epoxy resin decreases due to the plasticizing action, and the effect of increasing the peel strength of the metal foil (printed wiring) is further increased. When the epoxy equivalent becomes large, the plasticizing action becomes so remarkable that the heat resistance tends to be lowered. Therefore, the upper limit of the epoxy equivalent is considered as described above.

A prepreg according to the present invention is obtained by impregnating an organic fiber base material with the above epoxy resin composition and drying it, and a laminate is formed by heating and pressing a part or all of the prepreg layer. The metal foil-clad laminate is one in which a metal foil is integrated with the surface during the heating and pressing. Further, a printed wiring board according to the present invention includes an insulating layer formed by heating and pressing the prepreg layer.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The epoxy resin composition according to the present invention does not particularly limit the type of epoxy resin.
A bifunctional epoxy resin and a polyfunctional epoxy resin such as a trifunctional epoxy resin, a phenol novolak epoxy resin, a cresol novolak epoxy resin, and a bisphenol A novolak epoxy resin can be mixed or pre-reacted before use. Selection of a trifunctional epoxy resin or a polyfunctional epoxy resin improves heat resistance.
As the bifunctional epoxy resin, it is better to select a bisphenol F type epoxy resin than a bisphenol A type epoxy resin. This is because when the amount of the phosphorus compound is the same, the flame retardancy is more excellent. As a curing agent for epoxy resin,
Phenolic novolak resins can be selected.
By introducing a nitrogen atom into the molecular structure of the phenolic novolak resin, a resin having a nitrogen atom in the molecular structure can be obtained. For example, a melamine-modified phenolic novolak resin is selected. In addition, as a curing accelerator, 2
-Ethyl 4-methylimidazole and the like. The phosphorus compound which is a component of the resin composition is, for example, a phosphorus-based polyol, an addition-type phosphate ester that does not react with an epoxy resin, or a reactive phosphate ester that reacts with an epoxy resin. Since the reactive phosphate ester reacts with the epoxy resin and hinders the crosslinking reaction between the phenolic novolak resin as the curing agent and the epoxy resin, the addition type phosphate ester is preferably selected.

The epoxy resin composition according to the present invention can enhance flame retardancy by blending an inorganic compound powder such as aluminum hydroxide or magnesium hydroxide. However, care should be taken not to increase the blending amount. If the amount of the inorganic compound powder is large, the inorganic compound powder remains on the surface of the prepreg, and the adhesiveness at the interface between the metal foil (printed wiring) and the resin decreases. As long as the amount does not decrease the adhesiveness, it does not prevent blending of an inorganic compound powder such as aluminum hydroxide or magnesium hydroxide for imparting flame retardancy.

The organic fiber base material impregnated with the epoxy resin composition is preferably a nonwoven fabric containing aromatic polyamide fibers as a main component. This nonwoven fabric is manufactured by forming fibers dispersed in water into a sheet. The resinous binder in the form of an emulsion is sprayed on the paper-made nonwoven fabric, dried by heating and cured by the resin binder to obtain a nonwoven fabric having sufficient strength. For printed wiring boards and multilayer printed wiring boards, it is required to improve the solder connection reliability of electronic components mounted by soldering. For this purpose, it is essential to reduce the thermal expansion of the insulating layer, and it is a preferable embodiment to select an aromatic polyamide fiber having a negative coefficient of thermal expansion as the organic fiber constituting the nonwoven fabric. The aromatic polyamide fibers are classified into para-based and meta-based. Preferably, the content of the para-based aromatic polyamide fiber in the fibers constituting the nonwoven fabric is set to 50% by mass or more. This is because the selection of the para-aromatic polyamide fiber is more advantageous for lowering the thermal expansion and is excellent in heat resistance and moisture resistance.

The prepreg is produced by impregnating the above nonwoven fabric with the above epoxy composition and drying. Printed wiring boards
First, a metal foil is superimposed on the prepreg layer, and these are heated and pressed to form a metal foil-clad laminate, and the metal foil is etched into a predetermined wiring pattern to be manufactured. A multilayer printed wiring board is manufactured by laminating a metal foil on the printed wiring board via a prepreg by heat and pressure molding, and etching the metal foil into a predetermined wiring pattern. Further, a metal foil may be stacked on the surface via a prepreg and integrated by heating and pressing, and the metal foil may be etched into a predetermined wiring pattern to increase the number of wiring layers. In another method, a prepreg is interposed between a plurality of printed wiring boards, and a metal foil is overlaid on the surface via the prepreg,
These are integrated by heat and pressure molding, and the metal foil is etched into a predetermined wiring pattern. Laminated boards and printed wiring boards are prepregs and other prepregs according to the present invention,
For example, using a combination of glass fiber base prepreg,
You may comprise.

[0015]

Embodiments will be described below. Hereinafter, the printed wiring board is not specifically described, but the configuration and the manufacturing method are as described above, and thus the description is omitted. In order to confirm the flame retardancy, heat resistance and printed wiring peel strength of the insulating layer of the printed wiring board, in the following example, for convenience, 18 μm-thick copper foil was placed on both sides where five prepregs were stacked and heated and pressed. Molded copper-clad laminate (0.5mm
Thickness) was manufactured and subjected to a test.

Conventional Example 1 A para-aromatic polyamide fiber chop ("Technola" manufactured by Teijin) was dispersed in water and formed into a sheet. To this, a resin binder composed of a bisphenol A type epoxy resin and an isocyanate resin is sprayed in the form of an emulsion of an aqueous dispersion medium, and dried at 160 ° C. for 30 minutes.
A nonwoven fabric of 60 g / m ² was obtained. The adhesion amount of the resin binder is 8% by mass. The above nonwoven fabric is used as a base material, and as an epoxy resin composition impregnated in the nonwoven fabric, 31 parts by mass of a bisphenol A type epoxy resin (epoxy equivalent 212), 20 parts by mass of a trifunctional epoxy resin, 19 parts by mass of a phenol novolak resin as a curing agent, and bromine 30 parts by mass of a functionalized phenol novolak resin, 0.2 parts by mass of 2-ethyl 4-methylimidazole as a curing accelerator, and methyl ethyl ketone 3
It was dissolved in 0 parts by mass to prepare a varnish. The varnish was impregnated into the nonwoven fabric substrate and dried at 150 ° C. for 5 minutes to obtain a prepreg. The content of the resin is 52% by mass. Using the prepreg, the above-mentioned copper-clad laminate was manufactured. The molding conditions are heating and pressure molding at a temperature of 170 ° C. and a pressure of 4.9 MPa for 60 minutes.

Examples 1 to 11, Comparative Examples 1 to 4, and Example 1
2-15, Comparative Examples 7-8 Bisphenol A type epoxy resin (epoxy equivalent 18
5), trifunctional epoxy resin, phenol novolak resin, melamine-modified phenol novolak resin (nitrogen content 20% by mass), condensed phosphate ester (addition type, phosphorus content 9% by mass), 2-ethyl 4-methylimidazole Was dissolved in methyl ethyl ketone to prepare a varnish. The total mass% of phosphorus and nitrogen in the resin solid content (P, N mass%), the mass ratio of phosphorus and nitrogen contained (phosphorus / nitrogen), and the mass% of bisphenol A type epoxy resin (bis A epoxy) The blending ratio of the phenol novolak resin and the melamine-modified phenol novolak resin, and the blending amount of the condensed phosphoric acid ester were adjusted so that the respective blending ratios shown in Tables 1 to 3 were obtained. The amount of the trifunctional epoxy resin was adjusted. Otherwise, a copper-clad laminate was manufactured in the same manner as in Conventional Example 1.
The above adjustment can also be made by changing the nitrogen content of the melamine-modified phenol novolak resin and by changing the phosphorus content of the condensed phosphate ester.

[0018]

[Table 1]

[0019]

[Table 2]

[0020]

[Table 3]

Comparative Example 5 Bisphenol A type epoxy resin (epoxy equivalent 18
5) A varnish was prepared by dissolving trifunctional epoxy resin, phenol novolak resin, melamine-modified phenol novolak resin (nitrogen content: 20% by mass), and 2-ethyl 4-methylimidazole in methyl ethyl ketone. So that the content of nitrogen in the resin solids is 6.5 mass%,
The mixing ratio of the phenol novolak resin and the melamine-modified phenol novolak resin was adjusted. Otherwise, a copper-clad laminate was manufactured in the same manner as in Conventional Example 1.

Comparative Example 6 Bisphenol A type epoxy resin (epoxy equivalent 18
5) A varnish was prepared by dissolving trifunctional epoxy resin, phenol novolak resin, condensed phosphate ester (addition type, phosphorus content 9 mass%), and 2-ethyl 4-methylimidazole in methyl ethyl ketone. The mixing ratio of the condensed phosphoric acid ester was adjusted so that the phosphorus content in the resin solid content was 6.5% by mass. Other than that, Conventional Example 1
A copper-clad laminate was manufactured in the same manner as described above.

Tables 4 to 7 show the results of evaluating the solder heat resistance, flame retardancy, and copper foil peel strength of the copper-clad laminates of the above examples. Each characteristic shown in the table was evaluated as follows. The solder heat resistance was measured in accordance with JIS C-6481 by floating the sample in a solder bath at 300 ° C. and measuring the time until the sample swelled. The flame retardance was measured by measuring the after-flame time based on the UL-94 test method. Copper foil peel strength is JIS
It measured according to C-6481.

[0024]

[Table 4]

[0025]

[Table 5]

[0026]

[Table 6]

When bisphenol A type epoxy resin is selected as a bifunctional epoxy resin from Examples 9 to 11 and Comparative Examples 3 and 4, the total content of phosphorus and nitrogen in the resin solid content is adjusted to 5.5 to 7 It can be understood that heat resistance and flame retardancy can be ensured for the first time by setting the range of 0.7. Also,
It is clear from Examples 1 to 8 and Comparative Examples 1 and 2 that (phosphorus / nitrogen) must be in the range of 0.2 / 1 to 1/1 in order to secure heat resistance and flame retardancy. It is. From a comparison between Examples 2 to 4 and Examples 1 to 5 to 8, (phosphorus /
It can also be understood that by setting (nitrogen) in the range of 0.3 / 1 to 0.6 / 1, sufficient flame retardancy can be secured while maintaining heat resistance at an extremely good level. Example 1
From a comparison between 0, 13 to 15 and Example 12 and Comparative Examples 7 and 8, by containing bisphenol A type epoxy resin in an amount of 5 to 20% by mass, a good copper foil was obtained while ensuring heat resistance and flame retardancy. It can be understood that the peel strength can be maintained. Comparative Example 5 shows that flame retardancy cannot be ensured only by blending a resin having a nitrogen atom in the molecular structure, and Comparative Example 6 shows that flame retardancy can be secured only by blending a phosphorus compound. This indicates that the heat resistance becomes extremely low.

Examples 16 to 26, Comparative Examples 9 to 12, Examples 27 to 30, and Comparative Example 13 Bisphenol F type epoxy resin (epoxy equivalent 16
7), trifunctional epoxy resin, phenol novolak resin, melamine-modified phenol novolak resin (nitrogen content: 20% by mass), condensed phosphate ester (addition type, phosphorus content: 9% by mass), 2-ethyl 4-methylimidazole Was dissolved in methyl ethyl ketone to prepare a varnish. The total mass% of phosphorus and nitrogen in the resin solid content (P, N mass%), the mass ratio of phosphorus and nitrogen contained (phosphorus / nitrogen), and the mass% of bisphenol F type epoxy resin (bis F epoxy) The blending ratio of the phenol novolak resin and the melamine-modified phenol novolak resin, and the blending amount of the condensed phosphoric acid ester were adjusted so that the respective blending ratios shown in Tables 7 to 9 were obtained. The amount of the trifunctional epoxy resin was adjusted. Otherwise, a copper-clad laminate was manufactured in the same manner as in Conventional Example 1.
The above adjustment can also be made by changing the nitrogen content of the melamine-modified phenol novolak resin and by changing the phosphorus content of the condensed phosphate ester.

[0029]

[Table 7]

[0030]

[Table 8]

[0031]

[Table 9]

With respect to the copper-clad laminates of Examples 1 to 30 and Comparative Examples 9 to 13, the results of evaluating the solder heat resistance, flame retardancy, and copper foil peel strength are shown in Tables 10 to 12.

[0033]

[Table 10]

[0034]

[Table 11]

[0035]

[Table 12]

From Examples 24 to 26 and Comparative Examples 11 and 12, when a bisphenol F type epoxy resin is selected as the bifunctional epoxy resin, the total content of phosphorus and nitrogen in the resin solid content is 2 to 7.7. It can be understood that heat resistance and flame retardancy can be ensured for the first time by setting the range. Further, in order to ensure heat resistance and flame retardancy, (phosphorus / nitrogen) must be in the range of 0.2 / 1 to 1/1. It is clear from From the comparison between Examples 17 to 19 and Examples 16 and 20 to 23, (phosphorus / nitrogen) was changed from 0.3 / 1 to 0.6 / 1.
It can also be understood that by setting the range, the sufficient flame retardancy can be secured while maintaining the heat resistance at an extremely good level. Furthermore, from the comparison between Examples 25 and 28 to 30, Example 27, and Comparative Example 13, it was found that by containing 5 to 30% by mass of the bisphenol F type epoxy resin, good heat resistance and flame retardancy were ensured. It can be understood that the copper foil peel strength can be maintained. Examples 12 to 15 and Examples 27 to 3
From the comparison of 0, by selecting a bisphenol F type epoxy resin from a bisphenol A type epoxy resin as the bifunctional epoxy resin, the flame retardancy is further improved while maintaining the heat resistance and the copper foil peel strength. Can understand.

Examples 31 to 36 Bisphenol F type epoxy resin, trifunctional epoxy resin, phenol novolak resin Melamine-modified phenol novolak resin (nitrogen content 2
0% by mass), a condensed phosphate ester (addition type, phosphorus content 9% by mass), and 2-ethyl 4-methylimidazole were dissolved in methyl ethyl ketone to prepare a varnish. Total mass% of phosphorus and nitrogen in resin solids in resin solids
(P, N mass%), the mass ratio of phosphorus to nitrogen (phosphorus / nitrogen), and the mass% of bisphenol F type epoxy resin (bisF epoxy) are as shown in Table 13, The mixing ratio of the phenol novolak resin and the melamine-modified phenol novolak resin and the mixing amount of the condensed phosphate ester were adjusted, and the mixing amounts of the bisphenol F epoxy resin and the trifunctional epoxy resin were adjusted.
The epoxy equivalent of the bisphenol F type epoxy resin of each example is also as shown in Table 13. Otherwise, a copper-clad laminate was manufactured in the same manner as in Conventional Example 1.

[0038]

[Table 13]

Table 14 shows the results of evaluating the solder heat resistance, flame retardancy, and copper foil peel strength of the copper-clad laminates of Examples 31 to 36 described above.

[0040]

[Table 14]

From a comparison between Examples 31 to 35 and Example 36, it can be understood that better heat resistance can be maintained when the epoxy equivalent of the bisphenol F type epoxy resin is 150 to 2300.

[0042]

As described above, by applying the epoxy resin composition according to the present invention to an organic fiber base material, it is possible to secure sufficient flame retardancy with no halogen and to obtain a printed wiring board. The heat resistance also reaches a level with no problem. Particularly, (phosphorus / nitrogen) is 0.3 / 1 to 0.6 / 1.
Within this range, sufficient flame retardancy can be ensured while maintaining the heat resistance at an extremely good level. Furthermore, the peel strength of the metal foil (printed wiring) can be maintained at a favorable level by specifying the content of the bifunctional epoxy resin.

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Claims (10)

[Claims] 1. An epoxy resin composition for impregnating an organic fiber base material, comprising bisphenol A as a bifunctional epoxy resin.
Type epoxy resin, trifunctional or higher polyfunctional epoxy resin, furthermore, a phosphorus compound, and a resin having a nitrogen atom in the molecular structure.
% Or less, and the total content of phosphorus and nitrogen in the resin solid content is 5.5 to 7.
An epoxy resin composition for impregnating an organic fiber base material, wherein the mass ratio of phosphorus and nitrogen (phosphorus / nitrogen) is 0.2 / 1 to 1/1. 2. An epoxy resin composition for impregnating an organic fiber base material, comprising bisphenol F as a bifunctional epoxy resin.
Type epoxy resin, trifunctional or higher polyfunctional epoxy resin, furthermore, a phosphorus compound, and a resin having a nitrogen atom in the molecular structure.
Mass% or less, the total content of phosphorus and nitrogen in the resin solid content is 2 to 7.7 mass%, and the mass ratio of phosphorus and nitrogen contained (phosphorus /
Nitrogen) is from 0.2 / 1 to 1/1, the epoxy resin composition for impregnating an organic fiber base material. 3. The epoxy resin composition for impregnating an organic fiber substrate according to claim 2, wherein the bisphenol F type epoxy resin has an epoxy equivalent of 150 to 2300. 4. The method according to claim 1, wherein the content of the bifunctional epoxy resin is 5% by mass or more based on the solid content of the resin.
3. The epoxy resin composition for impregnating an organic fiber base material according to any one of 3. 5. The epoxy resin composition for impregnating an organic fiber substrate according to claim 1, wherein the phosphorus / nitrogen content is 0.3 / 1 to 0.6 / 1. 6. A prepreg obtained by impregnating and drying an organic fiber base material with the epoxy resin composition according to any one of claims 1 to 5. 7. The prepreg according to claim 6, wherein the organic fiber base material is a nonwoven fabric base material containing an aromatic polyamide fiber as a main component. 8. A laminate obtained by heating and pressing a part or all of the prepreg layer according to claim 6 or 7. 9. A metal foil-clad laminate wherein the metal foil is integrated on at least one side of the laminate according to claim 8. 10. A printed wiring board comprising an insulating layer obtained by heating and pressing the prepreg layer according to claim 6 or 7.