JPH093217A - Production of prepreg - Google Patents

Abstract

PURPOSE: To provide a method for producing a prepreg, capable of giving the composite material small in linear thermal expansion coefficient and heat resistance after subjected to a moisture-absorbing treatment, by adding inorganic particles to a reinforcing material, impregnating the mixture with a resin varnish and subsequently drying the product. CONSTITUTION: A method for producing a prepreg comprises adding inorganic particles having an average particle diameter of <=1000nm to a reinforcing material in an amount of 1-30 pts.wt. per 100 pts.wt. of the reinforcing material, and subsequently impregnating the treated reinforcing material with a resin varnish under either of the below-described conditions. (1) The impregnation is performed under a vacuum condition of 1-300Torr. (2) The impregnation is performed, while ultrasonic oscillation is imparted to the resin varnish. (3) The impregnation is performed, while 15-30Hz vibrations are imparted to the resin varnish with a vibration spring immersed in the resin varnish. (4) The impregnation is performed by immersing the reinforcing material in a solvent subjected to a vacuum defoaming treatment, and subsequently further immersing the treated reinforcing material in the resin varnish subjected to a vacuum defoaming treatment to impregnate the resin varnish into the reinforcing material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a prepreg obtained by impregnating a reinforcing material with a resin varnish and then drying it.

[0002]

2. Description of the Related Art As a recent trend of materials used for electronic devices, there is an attempt to realize high speed and high density as well as miniaturization and weight reduction. Leadless chip carrier (LCC) is one of the means to achieve the purpose.
Surface mounting technology (SMT) of the. For example, when the LCC of alumina is directly mounted on the printed circuit board, if the thermal expansion coefficients of the alumina and the printed circuit board are different,
Cracks occur in the solder at the joint due to thermal history. Therefore, in the case of direct mounting, the thermal expansion coefficient of the printed circuit board should be the same as that of the LCC (7 ppm for alumina).
/ ° C) is desirable. further,
There have also been attempts to directly mount bare silicon chips in leadless fashion. For that purpose, the thermal expansion coefficient of the printed circuit board must be the same as that of silicon (3-4 ppm /
(° C) is desirable.

As a means for reducing the coefficient of thermal expansion of a printed circuit board, the inventors of the present invention have filed Japanese Patent Application No. 6-108.
No. 816 is a composite material in which a resin is reinforced by a reinforcing material composed of strands formed by bundling monofilaments, and the strands have an average particle diameter of 1000 nm.
A low thermal expansion composite material containing the following inorganic particles in a proportion of 1 part by weight or more based on 100 parts by weight of the reinforcing material is proposed. However, in this composite material, it was found that swelling may occur when a solder test is performed after moisture absorption treatment such as PCT treatment. It is considered that the reason for this is that the inclusion of inorganic particles in the strands creates gaps in the strands where the resin is less likely to enter, creating pores.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances. An object of the present invention is to provide a reinforcing material composed of strands formed by bundling monofilaments with an average particle diameter of 1000 nm or less. The method of manufacturing a prepreg produced by impregnating the reinforcing material with a resin varnish after including the inorganic particles, and then drying the prepreg, which has a small coefficient of thermal expansion and is excellent in heat resistance after moisture absorption treatment. It is an object of the present invention to provide a method for producing a prepreg capable of obtaining a composite material.

[0005]

According to a first aspect of the present invention, there is provided a method for producing a prepreg, which comprises impregnating a resin varnish into a reinforcing material composed of strands formed by bundling monofilaments,
Then, in the method for producing a prepreg obtained by drying, before impregnating the reinforcing material with a resin varnish, 1 to 30 parts by weight of the inorganic particles having an average particle size of 1000 nm or less are added to the strand with respect to 100 parts by weight of the reinforcing material. And the resin varnish impregnation into the reinforcing material is 1 to 300 To
It is characterized in that it is carried out under a reduced pressure condition of rr.

According to a second aspect of the present invention, there is provided a method for producing a prepreg, which comprises impregnating a resin varnish into a reinforcing material composed of strands formed by bundling monofilaments and then drying the prepreg. Prior to impregnating with varnish, the strands had an average particle size of 10
Inorganic particles having a size of 00 nm or less are included in a proportion of 1 to 30 parts by weight with respect to 100 parts by weight of the reinforcing material, and the resin varnish is impregnated into the reinforcing material while applying ultrasonic vibration to the resin varnish. And

According to a third aspect of the present invention, there is provided a method for producing a prepreg, which comprises impregnating a reinforcing material composed of strands obtained by bundling monofilaments with a resin varnish and then drying the prepreg. Prior to impregnating with varnish, the strands had an average particle size of 10
Inorganic particles of 00 nm or less were contained at a ratio of 1 to 30 parts by weight with respect to 100 parts by weight of the reinforcing material, and impregnation of the resin varnish into the reinforcing material was performed at a frequency of 15 to 30 Hz by a vibration spring immersed in the resin varnish. It is characterized in that the vibration is applied to the resin varnish.

According to a fourth aspect of the present invention, there is provided a method for producing a prepreg, which comprises impregnating a resin varnish into a reinforcing material composed of strands formed by bundling monofilaments and then drying the prepreg. Prior to impregnating with varnish, the strands had an average particle size of 10
Inorganic particles of 00 nm or less are contained in a ratio of 1 to 30 parts by weight with respect to 100 parts by weight of the reinforcing material, and the reinforcing material is decompressed when impregnating the resin varnish into the reinforcing material containing the inorganic particles in the strand. It is characterized in that it is immersed in a defoamed solvent and then further immersed in a resin varnish that has been degassed under reduced pressure to impregnate the reinforcing material with the resin varnish.

A method for producing a prepreg according to a fifth aspect of the present invention is the method for producing a prepreg according to any one of the first to fourth aspects, wherein the strands of the reinforcing material before being impregnated with the resin varnish have an average particle size of Inorganic particles having a particle size of 1000 nm or less are included in the reaction product of the metal alkoxide, and the content of the reaction product of the metal alkoxide is the aforementioned inorganic particle 1.
It is characterized in that it is 20 parts by weight or less with respect to 00 parts by weight.

Hereinafter, the present invention will be described in detail. As the reinforcing material in the present invention, a material composed of strands formed by bundling monofilaments is used. The monofilament preferably has low thermal expansion, but is not particularly limited. The material of the monofilament is not particularly limited, but is preferably one or more kinds of glass (for example, E glass, D glass, Q glass, S glass, T glass, etc.) and aramid resin. Regarding the length of the strand, long fibers or short fibers may be used. From the viewpoint of low thermal expansion, the form of the reinforcing material is preferably such that the resin content is as small as possible. The reinforcing material in such a form is not particularly limited, but may be a mat, a sheet (for example, cloth (there is a weave such as plain weave, or satin weave), etc.), and a fiber molded body such as a composite of these. It is illustrated. Of the above-mentioned reinforcing materials, glass cloth is particularly preferable. The reason is,
This is because the cross shape is dense and the resin content can be reduced, and the filament continuity is high, which is effective in reducing the thermal expansion of the composite material. Further, glass is preferable because it is inexpensive and stable long fibers can be obtained.

The inorganic particles having an average particle diameter of 1000 nm or less contained in the strands constituting the reinforcing material are themselves materials having a low thermal expansion. The coefficient of thermal expansion is not particularly limited, but is preferably 10 ppm / ° C. or less. If the thermal expansion coefficient of the inorganic particles is larger than 10 ppm / ° C, the thermal expansion coefficient of the composite material will be alumina (7 ppm /
This is because it becomes too large in comparison with silicon (3 to 4 ppm / ° C).

Average particle size of 1000 n included in the strand
It is important that the amount of the inorganic particles of m or less is within the range of 1 to 30 parts by weight with respect to 100 parts by weight of the reinforcing material before the inorganic particles are contained. If this amount is less than 1 part by weight, the composite material having a small coefficient of thermal expansion, which is the object of the present invention, cannot be obtained, and the amount of the inorganic particles exceeds 30 parts by weight with respect to 100 parts by weight of the reinforcing material. And the moisture resistance of the composite material tends to deteriorate.

The reason for using the inorganic particles having an average particle diameter of 1000 nm or less is as follows. Since the monofilaments that compose the strands are usually several μm thick, the gap between the monofilaments is on the order of microns. Therefore, in order to easily include the inorganic particles even inside the strands, the average particle size is 1 μm. (= 1000
This is because it is preferably less than or equal to (nm). further,
Inorganic particles having a small average particle diameter are preferable because they are easily monodispersed in a treatment liquid containing water or the like as a medium.

The average particle size of the inorganic particles is 1
More preferred are ~ 100 nm colloidal particles. This is because such an inorganic particle has a smaller particle size, so that it can enter the gap between the narrower strands. However, the smaller the average particle size of the colloidal particles, the better. If it is less than 1 nm, the specific surface area of the colloidal particles becomes very large, which makes it difficult to control the interface with the resin. The lower limit of the average particle size is 1
nm.

The inorganic particles having an average particle diameter of 1000 nm or less are not particularly limited, but submicron-order commercially available particles such as fused silica and fine particle alumina are preferable. The colloidal particles having a smaller particle size are not particularly limited, but sol such as silica sol, alumina sol, titania sol, ultrafine particle silica, and ultrafine particle titania are preferable. Among these colloidal particles, silica is particularly preferable. The reason is that silica is
This is because the coefficient of thermal expansion is low (0.55 ppm / ° C.) among particles that are easily available. In addition to the particles described above, submicron particles and colloidal particles can be obtained by mechanically crushing with a ball mill or the like by using balls having a small diameter. Here, since the material to be crushed is desired to be a low thermal expansion material, silica glass, E glass, glass such as T glass, crystallized glass in which β-spodumene is precipitated, boron nitride, silicon nitride, mullite. , Aluminum nitride, cordierite, aluminum titanate (Al ₂ O ₃ TiO ₂ ), β-eucryptite and the like are preferable.

The strand may contain only inorganic particles having an average particle size of 1000 nm or less, but it is also possible to include a reaction product of a metal alkoxide as a low thermal expansion material in addition to the inorganic particles. Is. The metal alkoxide is completely soluble in a solvent such as alcohol. Therefore, the metal alkoxide has the property of being able to easily enter the inside of the strand by impregnating the treatment liquid containing the metal alkoxide into the reinforcing material, similarly to the above-mentioned inorganic particles. Since the reaction product of the metal alkoxide generally forms an inorganic film which is a continuous phase, it is different from the inorganic particles having an average particle size of 1000 nm or less in the present invention.

The metal alkoxide is not particularly limited, but silicon alkoxide, titanium alkoxide, aluminum alkoxide, magnesium alkoxide, lithium alkoxide and the like are preferable. The reason is that the reaction product of the metal alkoxide can be easily obtained by using these raw materials. Among these metal alkoxides, silicon alkoxide is more preferable. Silicon alkoxide is
This is because, among the above metal alkoxides, it is inexpensive, has high stability, and the reaction product, silica, has a low thermal expansion coefficient (0.55 ppm / ° C.). Further, the content ratio of the reaction product of the metal alkoxide is not particularly limited, but the reaction product of the metal alkoxide is preferably 20 parts by weight or less with respect to 100 parts by weight of the inorganic particles. If it exceeds 20 parts by weight,
This is because the composite material tends to impair the moisture resistance.

The resin reinforced with the reinforcing material is not particularly limited and may be appropriately selected depending on the use conditions. For example, epoxy resin, imide resin, phenol resin, PP.
Examples thereof include O (polyphenylene oxide) resin, fluororesin (for example, polytetrafluoroethylene, etc.), polyester resin, polycarbonate, polyethylene, polyethylene terephthalate, polypropylene, polystyrene and various modified resins thereof. These may be used alone or in combination of two or more.

In the present invention, at least one of the following four methods is applied when impregnating the reinforcing material with the resin varnish. It is performed under a reduced pressure condition of 1 to 300 Torr. Impregnation is performed while applying ultrasonic vibration to the resin varnish. 15-30H by vibrating spring immersed in resin varnish
Impregnation is performed while applying z vibration to the resin varnish. After the reinforcing material is dipped in a solvent that has been degassed under reduced pressure, it is further dipped in a resin varnish that has been degassed under reduced pressure to impregnate the reinforcing material with the resin varnish.

[0020]

In the present invention, when impregnating the reinforcing material with the resin varnish, at least one of the above-mentioned four methods (1) to (4) is carried out by allowing the resin to enter the inside of the reinforcing material, that is, the strand, Has the effect of reducing pores.
Therefore, according to the present invention, the coefficient of thermal expansion is small,
In addition, it becomes possible to manufacture a prepreg from which a composite material having excellent heat resistance after moisture absorption treatment can be obtained.

[0021]

EXAMPLES Examples of the present invention and comparative examples will be described below, but the present invention is not limited to the following examples.

Example 1 100 g of an aqueous colloidal silica solution (manufactured by Nissan Chemical Industries, trade name Snowtex OL, average particle diameter of colloidal silica 45 nm, colloidal silica 20% by weight) was used as solution A.

Separately, 2 g of an aminosilane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., product number KBM573) and 198 g of ethanol were stirred and mixed for 15 minutes to obtain a liquid B.

E-glass Nanako woven cloth (manufactured by Asahi Schwebel, product number 6777, AS450MV treated product, fiber diameter 7 μm, driving density (strands / 25 m
m): 37 lines / 25 mm length, 68 lines / 25 mm width,
First, the liquid A was impregnated. Then, after drying at room temperature for 1 minute, heat treatment was performed at 180 ° C. for 30 minutes. This coating operation was repeated twice. Then, impregnate the glass cloth with the liquid B and dry it at room temperature for 1 minute, and then at 110 ° C.
And heat treated for 10 minutes. As a result, a glass cloth containing inorganic particles and surface-treated with a silane coupling agent was obtained. In this case, Table 1 shows the content of the inorganic particles having an average particle diameter of 1000 nm or less with respect to 100 parts by weight of the reinforcing material (glass cloth) before including the inorganic particles.

Thereafter, the surface-treated glass cloth obtained above was impregnated with the epoxy resin varnish, and the interval was set to 0.
After squeezing with a 2 mm roll, dry at 150 ° C for 5 minutes,
I got a prepreg. Here, the impregnation of the resin varnish is 20To
It was carried out under a reduced pressure condition of rr. Next, four obtained prepregs were stacked and press molded for 90 minutes at 170 ° C. under a molding condition of 30 kg / cm ² to obtain a substrate (composite material). The content ratio of the resin component in the obtained substrate (composite material) is shown in Table 1.
Shown in

(Example 2) The same operation as in Example 1 was carried out except that the resin varnish was impregnated under atmospheric pressure and while ultrasonic vibration of 47 KHz was applied to the resin varnish. Thus, a prepreg and a substrate (composite material) were produced. Reinforcing material 1 before including inorganic particles in this case
Table 1 shows the content of the inorganic particles having an average particle size of 1000 nm or less with respect to 00 parts by weight and the content ratio of the resin component in the obtained substrate (composite material).

(Example 3) Except that the resin varnish was impregnated under atmospheric pressure and while vibrating a vibration spring immersed in the resin varnish, the resin varnish was vibrated at 15 Hz. Then, the same operation as in Example 1 was performed to produce a prepreg and a substrate (composite material). In this case, Table 1 shows the content of the inorganic particles having an average particle size of 1000 nm or less and the content ratio of the resin component in the obtained substrate (composite material) with respect to 100 parts by weight of the reinforcing material before including the inorganic particles.

Example 4 By the same operation as in Example 1, a glass cloth containing inorganic particles and surface-treated with a silane coupling agent was obtained.

Then, as described below, the surface-treated glass cloth obtained above was impregnated with the epoxy resin varnish by the method shown in the process chart of FIG. 1 and dried to obtain a prepreg. Next, stack four prepregs obtained,
The substrate (composite material) was obtained by press molding for 90 minutes at 170 ° C. under a molding condition of 30 kg / cm ² . In this case, Table 1 shows the content of the inorganic particles having an average particle size of 1000 nm or less and the content ratio of the resin component in the obtained substrate (composite material) with respect to 100 parts by weight of the reinforcing material before including the inorganic particles.

Here, a method of manufacturing the prepreg will be described with reference to the process chart of FIG. The solvent impregnation tank 3 is filled with the solvent 1 (dimethylformamide) which has been degassed under reduced pressure at 20 Torr for 30 minutes using the solvent decompression tank 2 equipped with the vacuum pump 10, and the resin varnish decompression tank 5 equipped with another vacuum pump 10 is used. The resin varnish 6 (epoxy resin varnish having the same composition as that used in Example 1) that had been degassed under reduced pressure at 20 Torr for 30 minutes was filled in the kiss roll impregnation tank 7 and the resin varnish tank 8 and the substrate 4 (the above The surface-treated glass cloth) is impregnated with the solvent 1 in the solvent impregnation tank 3,
Then, the resin varnish 6 in the kiss roll impregnation tank 7 is impregnated with the kiss roll, then the resin varnish 6 in the resin varnish tank 8 is impregnated, then squeezed with the squeeze roll 9, and then dried at 150 ° C. for 5 minutes, I got a prepreg. Note that FIG. 1 also shows a circulation path for circulating the solvent 1 and the resin varnish 6.

Example 5 After thoroughly mixing 22.5 g of ethanol and 0.52 g of tetraethoxysilane which is a metal alkoxide, an aqueous colloidal silica solution (manufactured by NISSAN CHEMICAL INDUSTRIES, trade name Snowtex OL, colloidal silica) was added. 75 g of an average particle diameter of 45 nm and colloidal silica of 20% by weight) was added, and the solution obtained by stirring for 15 minutes was used as the solution A, and the same operation as in Example 1 was performed to prepare a prepreg and a substrate ( Composite material) was prepared. In this case, the reinforcing material 100 before including the inorganic particles
Table 1 shows the content of the inorganic particles having an average particle size of 1000 nm or less with respect to parts by weight and the content ratio of the resin component in the obtained substrate (composite material).

Example 6 After thoroughly mixing 22.5 g of ethanol and 0.52 g of tetraethoxysilane which is a metal alkoxide, an aqueous colloidal silica solution (manufactured by Nissan Chemical Industries Ltd., trade name Snowtex OL, colloidal silica) was added thereto. 75 g of an average particle diameter of 45 nm and colloidal silica of 20% by weight) was added, and the solution obtained by stirring for 15 minutes was used as solution A, and impregnation of the resin varnish was performed.
Example 1 except that it was performed under atmospheric pressure and while applying ultrasonic vibration of 47 KHz to the resin varnish.
A prepreg and a substrate (composite material) were manufactured by performing the same operation as in. In this case, Table 1 shows the content of the inorganic particles having an average particle size of 1000 nm or less and the content ratio of the resin component in the obtained substrate (composite material) with respect to 100 parts by weight of the reinforcing material before including the inorganic particles.

(Example 7) 22.5 g of ethanol and 0.52 g of tetraethoxysilane, which is a metal alkoxide, were thoroughly mixed, and then an aqueous colloidal silica solution (manufactured by Nissan Chemical Industries, Ltd., trade name Snowtex OL, colloidal silica) was added. 75 g of an average particle diameter of 45 nm and colloidal silica of 20% by weight) was added, and the solution obtained by stirring for 15 minutes was used as solution A, and impregnation of the resin varnish was performed.
The same operation as in Example 1 was performed except that the vibration of the vibration spring immersed in the resin varnish was applied to the resin varnish while vibrating the resin varnish under the atmospheric pressure. A substrate (composite material) was produced.
In this case, Table 2 shows the content of the inorganic particles having an average particle diameter of 1000 nm or less and the content ratio of the resin component in the obtained substrate (composite material) with respect to 100 parts by weight of the reinforcing material before including the inorganic particles.

Example 8 After thoroughly mixing 22.5 g of ethanol and 0.52 g of tetraethoxysilane which is a metal alkoxide, an aqueous colloidal silica solution (manufactured by Nissan Chemical Industries, Ltd., trade name Snowtex OL, colloidal silica) was added. 75 g of an average particle diameter of 45 nm and colloidal silica of 20% by weight) was added, and the solution obtained by stirring for 15 minutes was used as solution A, and impregnation of the resin varnish was performed.
A prepreg and a substrate (composite material) were produced in the same manner as in Example 1 except that the method shown in the process diagram of FIG. 1 was performed in the same manner as in Example 4. In this case, Table 2 shows the content of the inorganic particles having an average particle diameter of 1000 nm or less and the content ratio of the resin component in the obtained substrate (composite material) with respect to 100 parts by weight of the reinforcing material before including the inorganic particles.

(Example 9) In Example 1, the work of coating the liquid A was repeated twice, but in this embodiment 9, the work of coating the liquid A was performed only once.
The content of the inorganic particles having an average particle diameter of 1000 nm or less based on 100 parts by weight of the reinforcing material was set to be different from that in Example 1.
Other operations were the same as in Example 1 to produce a prepreg and a substrate (composite material). In this case,
Table 2 shows the content of the inorganic particles having an average particle diameter of 1000 nm or less and the content of the resin component in the obtained substrate (composite material) with respect to 100 parts by weight of the reinforcing material before including the inorganic particles.

(Comparative Example 1) A prepreg and a substrate (composite material) were prepared in the same manner as in Example 1 except that the resin varnish was impregnated under atmospheric pressure. In this case, the reinforcing material 100 before including the inorganic particles
Table 2 shows the content of the inorganic particles having an average particle size of 1000 nm or less with respect to parts by weight and the content ratio of the resin component in the obtained substrate (composite material).

Comparative Example 2 A prepreg and a substrate (composite material) were prepared in the same manner as in Example 9 except that the resin varnish was impregnated under atmospheric pressure. In this case, the reinforcing material 100 before including the inorganic particles
Table 2 shows the content of the inorganic particles having an average particle size of 1000 nm or less with respect to parts by weight and the content ratio of the resin component in the obtained substrate (composite material).

In Examples 1 to 9 and Comparative Examples 1 and 2,
The content of the inorganic particles having an average particle diameter of 1000 nm or less and the content ratio of the resin component in the obtained substrate (composite material) with respect to 100 parts by weight of the reinforcing material before including the inorganic particles were determined as follows.

The weight per area of the reinforcing material before including the inorganic particles is measured in advance. Then, the weight of the inorganic particles (colloida silica) having an average particle diameter of 1000 nm or less contained in the reinforcing material is measured by weighing the weight of the reinforcing material after containing the inorganic particles, and the inorganic particles previously obtained from the value. Subtract the weight of the reinforcing material before inclusion. From the obtained numerical value, the content of the inorganic particles having an average particle diameter of 1000 nm or less relative to 100 parts by weight of the reinforcing material before including the inorganic particles is calculated and obtained. When the metal alkoxide (tetraethoxysilane) is used in combination with the inorganic particles (colloida silica), it is assumed that the amount of the reaction product of the metal alkoxide is such that the metal alkoxide contained in the solution A is completely hydrolyzed. Calculated from the charged amount of the liquid, the weight of the reinforcing material after containing the inorganic particles, and from the value obtained by subtracting the weight of the reinforcing material before including the inorganic particles obtained in advance, further of the metal alkoxide The weight of the inorganic particles (colloida silica) contained in the reinforcing material was determined by subtracting the amount of the reaction product.

The content ratio of the resin component in the obtained substrate (composite material) is determined by the weight per area of the reinforcing material and the weight per area of the substrate after the inorganic particles are contained and the surface treatment is performed. The weight was measured and the weight of the reinforcing material was subtracted from the weight of the substrate based on these measured values.

Further, the solder heat resistance test after the moisture absorption treatment was conducted on the substrates (composite materials) obtained in Examples 1 to 9 and Comparative Examples 1 and 2 as follows. First, sample 134
After being exposed to saturated steam at 3 ° C for 1 hour (PCT treatment), it was immediately immersed in a solder bath at 260 ° C for 60 seconds,
I checked to see if blistering occurred. The results obtained are shown in Tables 1 and 2 as ◯ when no blistering occurred and x when blistering occurred.

Further, regarding the substrates (composite materials) obtained in Examples 1 to 9 and Comparative Examples 1 and 2, the coefficient of thermal expansion of the glass cloth in the warp direction and the weft direction was measured by TMA (Ther.
momechanical Analyzer) and the results are shown in Tables 1 and 2. The measurement of the thermal expansion coefficient was performed from room temperature to 155 ° C. at a rate of temperature increase of 5 ° C./min, and the value of the thermal expansion coefficient of 40 to 80 ° C. was obtained.

[0043]

[Table 1]

[0044]

[Table 2]

From the results of Tables 1 and 2, it was confirmed that in the examples of the present invention, substrates having a small thermal expansion coefficient and excellent solder heat resistance after absorbing moisture were obtained.

[0046]

According to the method for producing a prepreg according to claims 1 to 5, when the resin varnish is impregnated into the reinforcing material containing the inorganic particles having an average particle diameter of 1000 nm or less, the following four methods are used. Apply at least one of these methods. It is performed under a reduced pressure condition of 1 to 300 Torr. Impregnation is performed while applying ultrasonic vibration to the resin varnish. 15-30H by vibrating spring immersed in resin varnish
Impregnation is performed while applying z vibration to the resin varnish. After the reinforcing material is dipped in a solvent that has been degassed under reduced pressure, it is further dipped in a resin varnish that has been degassed under reduced pressure to impregnate the reinforcing material with the resin varnish.

Therefore, according to the method of manufacturing a prepreg according to any one of claims 1 to 5, a prepreg which has a small coefficient of thermal expansion and can obtain a composite material having excellent heat resistance after moisture absorption treatment is manufactured. be able to.

[Brief description of drawings]

FIG. 1 is a simplified process diagram for explaining a process in one embodiment of the present invention.

[Explanation of symbols]

 1 solvent 2 solvent decompression pot 3 solvent impregnation bath 4 substrate 5 resin varnish decompression pot 6 resin varnish 7 kiss roll impregnation bath 8 resin varnish bath 9 squeeze roll 10 vacuum pump

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kiyoshiro Yamakawa 1048, Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works Co., Ltd.

Claims (5)

[Claims] 1. In a method for producing a prepreg, which comprises impregnating a reinforcing material composed of strands formed by bundling monofilaments with a resin varnish, and then drying the prepreg, before impregnating the reinforcing material with the resin varnish, the strand is Inorganic particles having an average particle diameter of 1000 nm or less are contained in a proportion of 1 to 30 parts by weight with respect to 100 parts by weight of the reinforcing material,
A method for producing a prepreg, which comprises impregnating a reinforcing material with a resin varnish under a reduced pressure condition of 1 to 300 Torr. 2. In a method for producing a prepreg, which comprises impregnating a reinforcing material composed of strands obtained by bundling monofilaments with a resin varnish, and then drying the prepreg, before impregnating the reinforcing material with the resin varnish, the strand is Inorganic particles having an average particle diameter of 1000 nm or less are contained in a proportion of 1 to 30 parts by weight with respect to 100 parts by weight of the reinforcing material,
A method for producing a prepreg, comprising impregnating a reinforcing material with a resin varnish while applying ultrasonic vibration to the resin varnish. 3. A method for producing a prepreg obtained by impregnating a reinforcing material composed of strands formed by bundling monofilaments with a resin varnish, and then drying the prepreg, before impregnating the reinforcing material with the resin varnish, the strand is Inorganic particles having an average particle diameter of 1000 nm or less are contained in a proportion of 1 to 30 parts by weight with respect to 100 parts by weight of the reinforcing material,
A method for producing a prepreg, characterized in that the reinforcing material is impregnated with the resin varnish while applying a vibration of 15 to 30 Hz to the resin varnish by a vibration spring immersed in the resin varnish. 4. In a method for producing a prepreg, which comprises impregnating a resin varnish into a reinforcing material composed of strands formed by bundling monofilaments and then drying, before impregnating the reinforcing material with the resin varnish, the strand is Inorganic particles having an average particle diameter of 1000 nm or less are contained in a proportion of 1 to 30 parts by weight with respect to 100 parts by weight of the reinforcing material,
When impregnating the resin varnish into the reinforcing material containing the inorganic particles in the strand, after dipping the reinforcing material in the solvent subjected to vacuum defoaming treatment, further immersed in the resin varnish subjected to vacuum defoaming treatment, the reinforcing material A method for producing a prepreg, which comprises impregnating a resin varnish with the resin. 5. The strand of the reinforcing material before impregnation with the resin varnish contains the reaction product of the metal alkoxide together with the inorganic particles having an average particle size of 1000 nm or less, and the content of the reaction product of the metal alkoxide is The inorganic particles 1
20 parts by weight or less with respect to 00 parts by weight, The method for producing a prepreg according to any one of claims 1 to 4, wherein