JP3322134B2 - Manufacturing method of prepreg - Google Patents

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 used as a material for a printed wiring board or the like.

[0002]

2. Description of the Related Art Conventionally, a prepreg used as a material for a printed wiring board is generally impregnated with a solution obtained by dissolving a thermosetting resin such as an epoxy resin in an organic solvent and then heating the substrate. It is manufactured by removing the organic solvent and B-stage (semi-cured) the thermosetting resin. But,
In such a conventional method, it is necessary to use a large amount of an organic solvent and further treat the removed organic solvent, and thus there is a problem in working environment and energy cost. Therefore, it has been proposed to produce a prepreg using a solventless epoxy resin composition as disclosed in, for example, Japanese Patent Publication No. 60-39288. However, when a prepreg is manufactured using a solventless epoxy resin composition, it is difficult to uniformly apply and impregnate the solventless epoxy resin composition on a substrate, Since the solvent-free epoxy resin composition of the present invention increases in viscosity with the passage of time, there is no difference in front and back in appearance, and there is a problem that it is difficult to produce a prepreg in which the resin composition is uniformly infiltrated. .

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to produce a prepreg using a solventless epoxy resin composition. It is possible to uniformly apply and impregnate the solvent-free epoxy resin composition on the substrate, and to suppress the increase in the viscosity of the solvent-free epoxy resin composition, so that there is no difference between the front and back in appearance, and the resin is uniform. It is an object of the present invention to provide a method for producing a prepreg, which makes it possible to produce a prepreg impregnated with a composition.

[0004]

According to a first aspect of the present invention, there is provided a method for producing a prepreg having two or more epoxy groups per molecule and having a viscosity at 25 ° C. of 1,000 to 3,000.
An epoxy resin (a) containing 50% by weight or more of a 0 cps liquid epoxy resin, and a phenol compound (b) having two or more phenolic hydroxyl groups per molecule;
A prepreg manufacturing method in which a solvent-free epoxy resin composition containing dicyandiamide (c) and a curing accelerator (d) is applied to one surface of a glass substrate by a die coater, and then heated to manufacture a prepreg. And a primary mixture obtained by heating and melting and mixing the epoxy resin (a) and the phenol compound (b) at 100 to 180 ° C. as the solvent-free epoxy resin composition, and the dicyandiamide and (c), up to use the curing accelerator (d), the solventless epoxy resin composition obtained by mixing above 90 ℃ temperature within 4 hours before applying to a glass substrate
A method for producing a prepreg, and the primary mixture,
Mix dicyandiamide (c) and curing accelerator (d)
In the solvent-free epoxy resin composition obtained by
90% by weight or more of the amide is dispersed as solvent-free epoxy resin.
It is characterized by being dispersed in a resin composition .

[0005]

[0006] manufacturing process of the prepreg of the invention according to claim 2, upon the manufacturing method according to claim 1 Symbol placement, mixing a primary mixture, dicyandiamide (c), the curing accelerator (d), dicyandiamide (c ) And a curing accelerator (d), or dicyandiamide (c) and a curing accelerator (d), each independently having one or more epoxy groups per molecule having a softening point of 90 ° C. or less. After mixing with a resin or a phenolic compound having a phenolic hydroxyl group of 1 or more per molecule having a softening point of 90 ° C. or less to prepare a premix, the premix and the primary mixture are mixed.

[0007] manufacturing process of the prepreg of the invention according to claim 3, upon the manufacturing method according to claim 1 Symbol placement, mixing a primary mixture, dicyandiamide (c), the curing accelerator (d), dicyandiamide (c ) Or the curing accelerator (d) has a softening point of 90 ° C. or lower.
An epoxy resin having at least one epoxy group per molecule or a phenol compound having at least one phenolic hydroxyl group per molecule having a softening point of 90 ° C. or less is used as a premix. And

According to a fourth aspect of the present invention, there is provided a method for producing a prepreg according to any one of the first to third aspects, wherein the primary mixture, dicyandiamide (c), and a curing accelerator (d) are used. Is mixed with an epoxy resin having one or more epoxy groups per molecule having a softening point of 90 ° C. or lower, or one or more phenolic compounds per molecule having a softening point of 90 ° C. or lower. A phenolic compound having a hydroxyl group is mixed to form a premix, and the premix is mixed with a dicyandiamide-containing premix kept in a fluid state, and a curing accelerator (d) or a curing accelerator (d) kept independently in a fluid state And a mixture with the primary mixture.

According to a fifth aspect of the present invention, there is provided a method for producing a prepreg according to any one of the first to fourth aspects, wherein the curing accelerator (d) contains two or more components. And a phosphorus-based curing accelerator as an essential component.

According to a sixth aspect of the present invention, there is provided a method for producing a prepreg according to any one of the first to fifth aspects, wherein the curing accelerator (d) comprises a compound represented by the following formula: It is characterized by containing as a component. However, in the formula, n represents an integer of 1 to 4, m represents an integer of 1 or 2, and R represents an m-valent organic group.

[0011]

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In the present invention, applying a solvent-free epoxy resin composition to one surface of a glass substrate with a die coater, and then heating to produce a prepreg, comprises adding the solvent-free epoxy resin composition to the substrate. It works to make it possible to apply and impregnate a fixed amount uniformly. Further, in the present invention, as a solvent-free epoxy resin composition, a primary mixture obtained by heating and melting and mixing an epoxy resin (a) and a phenol compound (b) at 100 to 180 ° C., and dicyandiamide (c) ,
The use of the solvent-free epoxy resin composition obtained by mixing the curing accelerator (d) at a temperature of 90 ° C. or less within 4 hours before application to the glass substrate is a problem at the time of application to the glass substrate. And acts to suppress an increase in the viscosity of the solvent-free epoxy resin composition.

[0013]

Embodiments of the present invention will be described.
The epoxy resin (a) is a compound having two or more epoxy groups per molecule, and contains 50% by weight or more of a liquid epoxy resin having a viscosity at 25 ° C. of 1,000 to 30,000 cps. When the viscosity is less than 1000 cps, the viscosity of the obtained solvent-free epoxy resin composition is too low, so that it is difficult to obtain a prepreg having a desired resin adhesion amount. There is a problem that it is difficult to uniformly impregnate the substrate with the epoxy resin composition because the viscosity of the product is too high. The reason why the above liquid epoxy resin is contained in an amount of 50% by weight or more is to make it possible to obtain a solventless epoxy resin composition having an appropriate viscosity at the time of application. Examples of the liquid epoxy resin include a bisphenol A type epoxy resin and a bisphenol F type epoxy resin, but are not limited to these. On the other hand, as the epoxy resin that can be used in combination with the liquid epoxy resin, for example, cresol novolac type epoxy resin,
A phenol novolak type epoxy resin is exemplified, but not limited thereto.

The phenol compound (b) having two or more phenolic hydroxyl groups per molecule includes, for example,
Bisphenol A, halogenated bisphenol A, bisphenol F, halogenated bisphenol F, phenol novolak, cresol novolak, pyrogallol and the like can be mentioned. Since the phenol compound (b) has two or more phenolic hydroxyl groups per molecule, it reacts with the epoxy resin (a). Therefore, the type of the phenol compound (b) affects the performance of the obtained cured product. For example, when a halogenated bisphenol A or a halogenated bisphenol F is used as the phenol compound (b), it has flame retardancy and flexibility. A cured product can be obtained.

Dicyandiamide (c) used in the present invention
Is a component that acts as a curing agent for the epoxy resin (a). This dicyandiamide has been generally used as a latent curing agent, but it is desirable to mix dicyandiamide in such a manner that the dicyandiamide is not dissolved in an epoxy resin or the like in order to exhibit the potential. It is effective to mix at 110 ° C. or less, preferably 70 ° C. or less. When dicyandiamide and epoxy resin are mixed under such a temperature condition, dicyandiamide hardly dissolves in epoxy resin and exists as dispersed particles. When 90% by weight or more of the total dicyandiamide blended in the solventless epoxy resin composition is not dissolved in the epoxy resin or the like and is dispersed in the solventless epoxy resin composition as dispersed particles, the dicyandiamide may be Full potential, 95% of all dicyandiamide
When the weight% or more is dispersed, the potential becomes more fully exhibited. As described above, since the solvent-free epoxy resin composition in which 90% by weight or more of all the dicyandiamide is dispersed as dispersed particles has a latent property, the reactivity is low at a low temperature (about 130 ° C. or less), and it is applied to a substrate. Since the increase in viscosity in the process up to impregnation is extremely small, good coatability, impregnation, and smoothness can be secured, and the epoxy resin composition has good reactivity at 150 ° C. or higher. It is possible to produce a prepreg by semi-curing. On the other hand, 10 of all dicyandiamides
In a solvent-free epoxy resin composition in which an amount exceeding 5% by weight is dissolved in an epoxy resin or the like, the amount of the epoxy resin composition is 5%.
When kept at a temperature condition of 0 ° C. or higher, the potential of dicyandiamide tends to be impaired, so that the epoxy resin composition undergoes a time-dependent change such as thickening, and it may not be possible to produce a prepreg of stable quality. .

In the present invention, dicyandiamide can be used in combination with another curing agent. As curing agents that can be used in combination, for example, diaminomaleonitrile, aromatic amine,
Hydrazide compounds, acid anhydrides, and the like.

The curing accelerator (d) used in the present invention includes a phosphorus-based curing accelerator, a compound represented by the above formula, an aliphatic tertiary amine, an aromatic tertiary amine, an imidazole, a diaza. Bicycloundecene, diazabicyclononene and the like can be mentioned. When the curing accelerator (d) contains two or more components and contains a phosphorus-based curing accelerator as an essential component, the epoxy resin (a) and the phenol compound ( The reaction of b) is selectively accelerated, and the reaction between the epoxy resin (a) and a curing agent such as dicyandiamide (c) and the epoxy resin (a) are promoted by another curing accelerator component used in combination with the phosphorus-based curing accelerator. ) And the phenolic compound (b) are both accelerated. Therefore, when a phosphorus-based curing accelerator and another curing accelerator are used in combination, the epoxy resin (a) and the phenol compound (b)
Phenol compound (b)
By selecting the type, it is possible to obtain a cured product having excellent flexibility, and the storage stability of the B-staged prepreg is preferably improved. Further, when the compound represented by the above formula is used as the curing accelerator (d), the curing acceleration at low temperatures is latent, so that the storage stability of the solvent-free epoxy resin composition and the B-staged prepreg are reduced. Good and preferable.

In the present invention, the solvent-free epoxy resin composition containing the above-described components, ie, the epoxy resin (a), the phenol compound (b), the dicyandiamide (c) and the curing accelerator (d) is used. A liquid composition having an appropriate viscosity is obtained at the time of application even without solvent, and a cured product produced using a prepreg obtained by applying and impregnating this composition on a glass substrate is excellent. It will have the performance which was good.

In the present invention, the solvent-free epoxy resin composition is applied to one surface of the glass substrate using a die coater. The die coater referred to here is a coater having a structure for discharging the solvent-free epoxy resin composition inside the die from the lip portion. When the solvent-free epoxy resin composition is applied to one surface of the glass substrate using such a die coater, a constant amount of the solvent-free epoxy resin composition can be uniformly applied to the substrate. That is, in the die coater method, since a fixed amount of the solvent-free epoxy resin composition is discharged from the lip portion, it is easier to make the coating amount constant than in the roll coater method or the dipping method. In the present invention, the solvent-free epoxy resin composition is applied to one surface of the glass substrate, but the solvent-free epoxy resin composition may be applied from the other surface of the glass substrate as needed. Good. Also,
As a glass substrate to be used, for example, glass cloth,
Glass nonwoven fabric (including glass paper) and the like can be exemplified.

In the present invention, a prepreg is produced by applying a solvent-free epoxy resin composition to one surface of a glass substrate and then heating. There is no particular limitation on the heating method, and the heating can be performed by a method such as non-contact heating or pressurized heating. Then, the resin penetrates to the back surface of the glass substrate by this heating, and the surface of the prepreg is smoothed and the epoxy resin composition is B-staged.

In the present invention, when preparing the solvent-free epoxy resin composition, the epoxy resin (a) and the phenol compound (b) are previously heated at 100 to 180 ° C. and melt-mixed to prepare a primary mixture. Since the epoxy resin (a) and the phenol compound (b) are melt-mixed without including the dicyandiamide (c) and the curing accelerator (d) in this manner, the epoxy resin (a) and the phenol compound (b) are rapidly mixed. Reaction is prevented. The reason for limiting the heating temperature at the time of melt mixing to 100 to 180 ° C. is 100 ° C.
If the temperature is less than 180 ° C., there is a disadvantage that a long time is required for melt mixing, and if the temperature is higher than 180 ° C., deterioration such as discoloration may occur.

In the present invention, the primary mixture, dicyandiamide (c) and the curing accelerator (d) are mixed at a temperature of 90 ° C. or less within 4 hours before applying the solvent-free epoxy resin composition to the glass substrate. This suppresses the viscosity increase of the epoxy resin composition. When the solvent-free epoxy resin composition is significantly thickened, the permeability to the glass substrate becomes poor, and the appearance of the obtained prepreg becomes different between the front and back sides, or the resin composition does not penetrate uniformly. Occurs. Furthermore, when the viscosity of the solventless epoxy resin composition is extremely high, hundreds of thousands of cps, even if it is attempted to apply the solventless epoxy resin composition to one surface of the glass substrate using a die coater, the viscosity is high. There is a problem that it becomes difficult to discharge from the die coater. In the present invention, since the viscosity of the epoxy resin composition is suppressed by limiting the mixing time and the heating temperature from the start of mixing as described above, there is no difference between the front and back sides in appearance, and the resin composition is uniform. It is possible to produce a prepreg that has been impregnated.

Further, when mixing the primary mixture, dicyandiamide (c) and curing accelerator (d), both dicyandiamide (c) and curing accelerator (d) or dicyandiamide (c) and curing accelerator are mixed. (D) is independently an epoxy resin having a softening point of 90 ° C. or lower and having one or more epoxy groups per molecule or a softening point of 90 ° C. or less.
After mixing with a phenolic compound having at least one phenolic hydroxyl group per molecule at a temperature of not more than 1 ° C. to form a premix, and then mixing the premix with the primary mixture, dicyandiamide (c) and curing It is preferable because the accelerator (d) can be efficiently and uniformly dispersed or dissolved in the epoxy resin composition. Also, the primary mixture and dicyandiamide (c)
When mixing the curing accelerator (d) with one of the dicyandiamide (c) and the curing accelerator (d), the epoxy having one or more epoxy groups per molecule having a softening point of 90 ° C. or less is used. When a resin or a phenolic compound having a phenolic hydroxyl group of 1 or more per molecule whose softening point is 90 ° C. or less is used as a premix, a component of the premix is used. Is preferable because it can be efficiently and uniformly dispersed or uniformly dissolved in the epoxy resin composition.

Further, when mixing the primary mixture, dicyandiamide (c) and the curing accelerator (d), dicyandiamide (c) is mixed with one or more epoxy groups per molecule having a softening point of 90 ° C. or less. An epoxy resin having a softening point of 90 ° C. or less and a phenolic compound having one or more phenolic hydroxyl groups per molecule are mixed with each other to form a premix, and this premix is independently mixed with a dicyandiamide-containing premix kept in a fluid state. When the hardening accelerator (d) or the hardening accelerator (d) -containing material kept in a fluidized state is mixed with the primary mixture, the dicyandiamide (c) and the hardening accelerator (d) are respectively mixed. Since the material kept in a fluid state is mixed with the primary mixture, it is easy to keep the viscosity of each material before mixing constant. Preferable because the quality of the object is more stable. As the curing accelerator-containing material, as described above, an epoxy resin having one or more epoxy groups per molecule having a softening point of 90 ° C. or lower, or one or more epoxy resins per molecule having a softening point of 90 ° C. or lower A phenolic compound having a phenolic hydroxyl group and a curing accelerator may be mixed to form a premix, or a component simply added to keep the fluidized state may be added to the curing accelerator.

The premix is a so-called masterbatch. The dicyandiamide (c) and the curing accelerator (d) used in the present invention are obtained by melting the epoxy resin (a) and the phenol compound (b). The addition amount is extremely small compared to the mixed primary mixture, and dicyandiamide (c) has poor compatibility with the epoxy resin (a) and the phenol compound (b). By mixing, it is easy to achieve uniformity of the obtained epoxy resin composition, and the occurrence of uneven curing and uneven performance when the prepreg is cured is suppressed. When heating is required when preparing the premix, it is desirable to set the heating temperature to 90 ° C. or lower so that the reaction in the premix does not proceed. Examples of the epoxy resin having a softening point of 90 ° C. or less and having one or more epoxy groups per molecule include, for example, bisphenol A epoxy resin and bisphenol F epoxy resin, but are not limited thereto. is not. Examples of the phenol compound having one or more phenolic hydroxyl groups per molecule having a softening point of 90 ° C. or less include, but are not limited to, phenol novolak and cresol novolak.

In the present invention, it is necessary to weigh a certain amount of each raw material before the coating process, mix the raw materials, and then supply them to the die coater. Each can be degassed under reduced pressure, or a specified amount of the material of each step is weighed using a gear pump or the like, and further, the epoxy resin composition is added to the die coater while performing melt mixing using a mixer that can be continuously supplied. It is desirable to use a means for supplying, since it becomes possible to supply an epoxy resin composition containing no air bubbles.

[0027]

EXAMPLES In the following Examples and Comparative Examples, the following raw materials were used. In addition, the viscosity measurement of raw materials and compounds is performed by ICI
It was measured by a cone type viscometer.

Epoxy resin 1: bisphenol A type epoxy resin having an epoxy equivalent of 190, viscosity at 25 ° C. = 13000 cps, manufactured by Yuka Shell Epoxy Co., Ltd., Epicoat 828 Epoxy resin 2: bisphenol F type epoxy resin having an epoxy equivalent of 180, 25 ° C. Viscosity at 4000 cps, manufactured by Dainippon Ink and Chemicals, Inc., trade name: EPICLON 830 Epoxy resin 3: Cresol novolac type epoxy resin having an epoxy equivalent of 210 Softening point: about 80 ° C, manufactured by Dainippon Ink and Chemicals, trade name: EPICLON N680 Dicyandiamide: Using a reagent Molecular weight = 84 Theoretical active hydrogen equivalent = 21 g / eq Phenol compound: Tetrabromobisphenol A (Using a reagent) Curing accelerator 1: Triphenylphosphine (Using a reagent) Curing accelerator 2: Table shown below Compound Curing accelerator melting point of about 200 ° C. manufactured by San-Apro Ltd. to, trade name UCAT 3503N curing accelerator 3: 2-ethyl-4-methylimidazole (using reagent)

[0029]

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(Example 1) Epoxy resin 1 (45 parts by weight) and epoxy resin 3 (13 parts by weight) were melt-mixed at 130 ° C, and tetrabromobisphenol A (35 parts by weight) was added. For 20 minutes to dissolve tetrabromobisphenol A and to mix the primary mixture E1
I got

On the other hand, dicyandiamide (3 parts by weight) and curing accelerator 3 (0.06 parts by weight) are kneaded with epoxy resin 1 (7 parts by weight) at 40 ° C. by using three rolls, and a liquid premix (master) is prepared. Batch) M1 was prepared. After the prepared premix M1 was stored at 40 ° C. for 20 minutes and 3 hours, the ratio of dicyandiamide dispersed as dispersed particles in the premix M1 to the total dicyandiamide blended was evaluated as dicyandiamide insolubility. The result was 99.9% after storage for 20 minutes and 99.7% after storage for 3 hours. The dicyandiamide insolubility was evaluated by the following method, and the dicyandiamide insolubility in the following Examples and Comparative Examples was evaluated in the same manner.

Evaluation method of dicyandiamide insolubility The weight of all dicyandiamide blended in a composition containing dicyandiamide as a composition to be evaluated is defined as b. The composition to be evaluated is diluted with about 10 times the weight of the composition to be evaluated using methylene chloride (using a reagent). Filter all the diluted liquids through a filter with an initial dry weight of x and a mesh size of about 10 microns. After completion of the filtration, the filter is thoroughly washed with fresh methylene chloride (5 to 10 times) to wash away components dissolved in methylene chloride. The washed filter is dried under reduced pressure at 60 ° C., and the weight y after drying is measured. The dicyandiamide insolubility is calculated by the following equation. Since dicyandiamide is hardly soluble in methylene chloride and the epoxy resin, phenolic resin, and curing accelerator are easily soluble, when sufficiently washed with methylene chloride, the filter is present in a dispersed state in the composition to be evaluated. The remaining dicyandiamide remains. Dicyandiamide insolubility = (y−x) × 100 / b

The primary mixture E1 was degassed under reduced pressure while being heated to 70 ° C., and the premix M1 was degassed under reduced pressure while being heated to 40 ° C. Then, E1 and M1 degassed under reduced pressure were supplied to the mixer while being weighed by the gear pump so as to have the above-mentioned weight ratio. Here, as for the raw material compounding ratio, when the total compounding amount of all epoxy resins and tetrabromobisphenol A is 100 parts by weight, the compounding parts by weight of dicyandiamide and the curing accelerator are the above-mentioned parts by weight.

Next, the mixture of E1 and M1 was mixed with a mixer while heating to 60 ° C. to prepare a solvent-free epoxy resin composition, and the solvent-free epoxy resin composition was then heated with a die coater heated to 60 ° C. Hopper. Next, the solvent-free epoxy resin composition in the hopper is discharged from the lip portion of the die coater, and a 0.1 mm-thick glass cloth (manufactured by Asahi Schwebel Co., Ltd., product number 216L) is manufactured using the production line shown in FIG. And heated with a 70 ° C. residual heat heater, and then heated with a floating dryer at 180 ° C. for 2 minutes to produce a prepreg. At this time, by changing the residence time in the hopper, two types of prepregs were prepared, one in which the time from the start of mixing of E1 and M1 in the mixer to the time of application was 20 minutes and the other in which the time was 3 hours. did. The dicyandiamide insolubility of each of the solventless epoxy resin composition having a coating time of 20 minutes and the solventless epoxy resin composition having a coating time of 3 hours was 99% and 3%, respectively. 97% of time
Met.

Each of the two types of prepregs was a prepreg in which the epoxy resin composition was uniformly applied and impregnated, and there was no difference in appearance between the front and back sides, and the penetration of the epoxy resin composition was good.

The primary mixture E1 in the initial state was
The melt viscosity at 0 ° C. was 3000 cps, and the increase rate of the melt viscosity when heated and stored at 70 ° C. reached 50% after 50 hours of storage. The melt viscosity at 40 ° C. in the initial state of the pre-mixture M1 is 2500 cps,
50% increase in melt viscosity when heated and stored at 40 ° C
Reached after storage for 4 hours. In addition, E1 and M
The melt viscosity at 60 ° C. in the initial state (at the time of mixing for 5 minutes with a mixer) of the solvent-free epoxy resin composition containing No. 1 was 6000 cps, and the rate of increase in the melt viscosity when heated and stored at 60 ° C. It reached 50% after 4 hours of storage.

Here, the production line shown in FIG. 1 will be described. This production line comprises, from the upstream side, an unwinding machine A for a glass cloth B having an unwinding roller A ′ and a take-over roller A ″, an accumulator C for enabling continuous operation when switching between the rollers A ′ and A ″, A die coater E having a hopper D, a backup roller F in which a metal roller is coated with a fluororesin or the like, a residual heat heater G, pressure rollers H and H ', and a plurality of nozzles for injecting heated gas. And a winding machine K for a prepreg J having a winding roller K ′ and a take-over roller K ″.

Example 2 As a preliminary mixture, kneading epoxy resin 1 (7 parts by weight) with dicyandiamide (3 parts by weight) and curing accelerator 2 (0.20 parts by weight) at 40 ° C. using three rolls. Liquid premix (master batch) M
2 was prepared, and a prepreg was produced using the production line shown in FIG. 1 in the same manner as in Example 1 except that this premix M2 was used. The ratio of the dicyandiamide dispersed as dispersed particles in the premix M2 after storing the prepared premix M2 at 40 ° C. for 20 minutes and 3 hours to the total dicyandiamide blended was evaluated as dicyandiamide insolubility. did. The result was 99.9% after storage for 20 minutes and 99.7% after storage for 3 hours.

When preparing the prepreg, the residence time in the hopper was changed in the same manner as in Example 1, so that the time from when mixing of E1 and M2 was started by the mixer to the time of coating was 20 minutes. Two types of prepregs were prepared, one that was used and one that was used for 3 hours. In addition, when the solvent-free epoxy resin composition was applied for 20 minutes and the solvent-free epoxy resin composition was used for 3 hours, the dicyandiamide insolubility was evaluated.
99% for 20 minutes and 98% for 3 hours.

Each of the two types of prepregs was a prepreg in which the epoxy resin composition was uniformly applied and impregnated, and there was no difference in appearance between the front and back sides, and the penetration of the epoxy resin composition was good.

Incidentally, 4 in the initial state of the premix M2 was prepared.
The melt viscosity at 0 ° C. was 2500 cps, and the rate of increase in melt viscosity when heated and stored at 40 ° C. reached 50% after 50 hours of storage. Furthermore, the melt viscosity at 60 ° C. in the initial state (at the time of mixing for 5 minutes with a mixer) of the solvent-free epoxy resin composition obtained by mixing E1 and M2 is 60.
The rate of increase in melt viscosity when heated and stored at 60 ° C. reached 50% after 8 hours of storage.

Example 3 As a premix, epoxy resin 1 (7 parts by weight), dicyandiamide (3 parts by weight), curing accelerator 1 (0.10 parts by weight), and curing accelerator 2 (0.
20 parts by weight) were kneaded at 60 ° C. using three rolls to prepare a liquid premix (master batch) M3, and the procedure was the same as in Example 1 except that this premix M3 was used. A prepreg was produced using the production line shown in FIG. The pre-mixture M3, which has been prepared, is heated at 40 ° C
The ratio of dicyandiamide dispersed as dispersed particles in the pre-mixture M3 after storage for 20 minutes and 3 hours in the total mixture of dicyandiamide was evaluated as dicyandiamide insolubility. The result was 99.9% after storage for 20 minutes and 99.7% after storage for 3 hours.

Also, when preparing the prepreg, by changing the residence time in the hopper in the same manner as in Example 1, the time from when mixing of E1 and M3 was started by the mixer to when coating was performed was 20 minutes. Two types of prepregs were prepared, one that was used and one that was used for 3 hours. In addition, when the solvent-free epoxy resin composition was applied for 20 minutes and the solvent-free epoxy resin composition was used for 3 hours, the dicyandiamide insolubility was evaluated.
99% for 20 minutes and 98% for 3 hours.

Both of the two types of prepregs obtained were uniformly coated and impregnated with the epoxy resin composition, had no difference in appearance on the front and back sides, and had good penetration of the epoxy resin composition. Further, the resin component was rubbed off from the prepreg prepared such that the time from the start of mixing to the application was 3 hours, and the resin component was molded at 170 ° C. for 90 minutes using a mold to obtain a 4 mm × 10 mm ×
A cured resin of 100 mm was prepared, and a bending test based on JIS standard C6481 was performed on the cured resin to measure a flexural modulus. A similar test was performed for the cases of Examples 1 and 2 to measure the flexural modulus, and the results were compared with those of Example 3. As a result, the hardening accelerator contained two or more types of components and was essential. It was found that the flexural modulus of the cured resin in Example 3 containing a phosphorus-based curing accelerator as a component was about 10% lower than those in Examples 1 and 2.

Note that the premix M3 was 4% in the initial state.
The melt viscosity at 0 ° C. was 2500 cps, and the rate of increase in melt viscosity when heated and stored at 40 ° C. reached 50% after 50 hours of storage. Furthermore, the melt viscosity at 60 ° C. in the initial state (at the time of mixing for 5 minutes with a mixer) of the solvent-free epoxy resin composition obtained by mixing E1 and M3 is 60.
It was 00 cps, and the rate of increase in melt viscosity when heated and stored at 60 ° C. reached 50% after storage for 6 hours.

Example 4 After epoxy resin 2 (40 parts by weight) and epoxy resin 3 (18 parts by weight) were melt-mixed at 130 ° C., tetrabromobisphenol A (35 parts by weight) was added, and the mixture was added at 130 ° C. The mixture is mixed for 20 minutes to dissolve the tetrabromobisphenol A, and the primary mixture E4
I got A prepreg was produced using the production line shown in FIG. 1 in the same manner as in Example 1 except that this E4 was used as a primary mixture. At this time, by changing the residence time in the hopper similarly to the first embodiment,
Two types of prepregs were prepared, one in which the time from the start of mixing 4 and M1 with the mixer to the application was 20 minutes and the other in 3 hours. The dicyandiamide insolubility was evaluated for each of the solventless epoxy resin composition in which the time until application was 20 minutes and the solventless epoxy resin composition in which the time was 3 hours.
Minutes were 99% and 3 hours were 97%.

Each of the two types of prepregs was a prepreg in which the epoxy resin composition was uniformly applied and impregnated, and there was no difference in appearance between the front and back sides and the penetration of the epoxy resin composition was good.

The primary mixture E4 in the initial state was
The melt viscosity at 0 ° C. was 2500 cps, and the rate of increase in melt viscosity when heated and stored at 70 ° C. reached 50% after 45 hours of storage. Furthermore, the melt viscosity at 60 ° C. in the initial state (at the time of mixing for 5 minutes with a mixer) of the solvent-free epoxy resin composition obtained by mixing E4 and M1 is 60.
The rate of increase in the melt viscosity when heated and stored at 60 ° C. reached 50% after 4 hours of storage.

Example 5 Epoxy resin 1 (33 parts by weight) and epoxy resin 3 (15 parts by weight) were melt-mixed at 130 ° C., and tetrabromobisphenol A (35 parts by weight) was added. The mixture was mixed for 20 minutes to dissolve the tetrabromobisphenol A, and the primary mixture E5
I got

On the other hand, dicyandiamide (3 parts by weight) was kneaded with epoxy resin 1 (7 parts by weight) at 40 ° C. using three rolls to prepare a liquid premix (master batch) M5A. Parts by weight) and curing accelerator 1
(0.20 parts by weight) and curing accelerator 2 (0.20 parts by weight)
Was heated and mixed at 70 ° C. and dispersed to prepare a liquid premix (master batch) M5B. The ratio of the dicyandiamide dispersed as dispersed particles in the premix M5A after storing the prepared premix M5A at 40 ° C. for 20 minutes and 3 hours to the total dicyandiamide blended was evaluated as the dicyandiamide insolubility. did. The result was 99.9% after storage for 20 minutes and 99.7% after storage for 3 hours.

The primary mixture E5 was degassed under reduced pressure while being heated to 70 ° C., and the premixes M5A and M5B were mixed.
Was heated to 40 ° C. and degassed under reduced pressure. Next, the degassed and degassed E5 and M5A were each weighed with a gear pump so as to have the above-mentioned weight ratio, and then mixed, and the mixed product and the premix M5B were weighed with a gear pump so as to have the above-mentioned weight ratio. And the mixture of E5, M5A and M5B is
C. to prepare a solventless epoxy resin composition by mixing while heating to 60.degree.
Was supplied to the hopper of the die coater, which had been heated to a temperature of 1 m. Next, the solvent-free epoxy resin composition in the hopper is discharged from the lip portion of the die coater, and a 0.1 mm-thick glass cloth (manufactured by Asahi Schwebel Co., Ltd., product number 216L) is manufactured using the production line shown in FIG. On one side and then 70
After heating with a residual heat heater at 180 ° C., the mixture was heated at 180 ° C. for 2 minutes with a floating dryer to produce a prepreg. At this time, by changing the residence time in the hopper,
Two types of prepregs were prepared, one in which the time from the start of mixing the mixture of E5, M5A and M5B with the mixer to the time of application was 20 minutes and the other was 3 hours. The dicyandiamide insolubility of each of the solventless epoxy resin composition having a coating time of 20 minutes and the solventless epoxy resin composition having a coating time of 3 hours was 99% and 3%, respectively. The time one was 98%.

Each of the two types of prepregs was a prepreg in which the epoxy resin composition was uniformly applied and impregnated, and there was no difference in appearance between the front and back sides, and the penetration of the epoxy resin composition was good. The melt viscosity at 70 ° C. in the initial state of the primary mixture E5 was 3000 cps, and the rate of increase in the melt viscosity when heated and stored at 70 ° C. was 5%.
It reached 0% after 50 hours of storage. The melt viscosity at 40 ° C. in the initial state of the pre-mixture M5A is 23.
It was 00 cps, and the rate of increase in melt viscosity when heated and stored at 40 ° C. reached 50% after storage for 30 days. The melt viscosity at 40 ° C. in the initial state of the pre-mixture M5B is 1800 cps, and the rate of increase in melt viscosity when heated and stored at 40 ° C. reaches 120% only at 120%.
Time was after storage. In addition, E5, M5A and M5B
The melt viscosity at 60 ° C. in the initial state (at the time of mixing for 5 minutes with a mixer) of the solvent-free epoxy resin composition mixed with 6000 is 6000 cps, and the rate of increase in the melt viscosity when heated and stored at 60 ° C. is 50%. % Reached after storage for 7 hours.

(Example 6) Epoxy resin 1 (33 parts by weight) and epoxy resin 3 (15 parts by weight) were melted and mixed at 130 ° C, and tetrabromobisphenol A (35 parts by weight) was added. The mixture was mixed for 20 minutes to dissolve the tetrabromobisphenol A, and the primary mixture E5
I got

On the other hand, dicyandiamide (3 parts by weight) was kneaded with epoxy resin 1 (7 parts by weight) at 40 ° C. using three rolls to prepare a liquid premix (master batch) M5A. The prepared pre-mixture M5A is
The ratio of dicyandiamide dispersed as dispersed particles in the pre-mixture M5A after storage for 0 minutes and 3 hours to all dicyandiamide blended was evaluated as dicyandiamide insolubility. The result was 99.9% after storage for 20 minutes and 99.7% after storage for 3 hours.

The primary mixture E5 was degassed under reduced pressure while heating to 70 ° C., and the premix M5A was degassed under reduced pressure while being heated to 40 ° C., and the curing accelerator 3 (0.06 parts by weight) was added at 50 ° C. Heated. Then E5 and M degassed under reduced pressure
5A were weighed with a gear pump to the above weight ratios, and then mixed.
The curing accelerator 3 (0.06 parts by weight) heated to 0 ° C. was fed to the mixer while being weighed to the above-mentioned weight ratio with a gear pump, and then the mixture of E5, M5A and the curing accelerator 3 was mixed with the mixer at 60%. The solvent-free epoxy resin composition was prepared by mixing while heating to ° C., and then the solvent-free epoxy resin composition was supplied to a hopper of a die coater heated to 60 ° C. Next, the solvent-free epoxy resin composition in the hopper is discharged from the lip of the die coater,
Using a production line shown in FIG. 1, a glass cloth (manufactured by Asahi Schwebel Co., Ltd., product number 216L) was coated on one side with a thickness of 0.1 mm and then heated with a preheater at 70 ° C. A prepreg was prepared by heating at 2 ° C. for 2 minutes. At this time, by changing the residence time in the hopper, the time from when the mixing of the E5 and M5A mixture and the curing accelerator 3 was started by the mixer to the time of application was set to 20 minutes and 3 hours. 2
Various kinds of prepregs were produced. In addition, about the solventless epoxy resin composition which set the time until application to 20 minutes, and the solventless epoxy resin composition which set it to 3 hours, respectively,
The dicyandiamide insolubility was evaluated to be 99% for 20 minutes and 97% for 3 hours.

Each of the two prepregs obtained was a prepreg in which the epoxy resin composition was uniformly applied and impregnated, and there was no difference in appearance on the front and back, and the penetration of the epoxy resin composition was good.

Note that the primary mixture E5 in the initial state
The melt viscosity at 0 ° C. was 3000 cps, and the increase rate of the melt viscosity when heated and stored at 70 ° C. reached 50% after 50 hours of storage. The melt viscosity at 40 ° C. in the initial state of the pre-mixture M5A was 2300 cps, and the rate of increase in the melt viscosity when heated and stored at 40 ° C. was 5%.
It reached 0% after 30 days of storage. Furthermore, E
5, the melt viscosity at 60 ° C. in the initial state (at the time of mixing for 5 minutes with a mixer) of the solvent-free epoxy resin composition in which M5A and the curing accelerator 3 are mixed is 6000 cps, and when heated and stored at 60 ° C. The rate of increase in melt viscosity is 5
It reached 0% after 4 hours of storage.

(Comparative Example 1) Epoxy resin 1 (52 parts by weight) and epoxy resin 3 (13 parts by weight) were melt-mixed at 130 ° C., and tetrabromobisphenol A (35 parts by weight), dicyandiamide ( 3 parts by weight)
And curing accelerator 3 (0.06 parts by weight)
For 15 minutes to prepare a solventless epoxy resin composition. The dicyandiamide insolubility immediately after the preparation of this resin composition was 72%. Next, this solvent-free epoxy resin composition was supplied to a hopper of a die coater heated to 60 ° C. Then, the time from the start of mixing as the solvent-free epoxy resin composition to the application is 20 minutes (20 minutes including the above 15 minutes at 130 ° C.), and the solvent-free The epoxy resin composition was discharged from the lip portion of the die coater, and was attempted to be applied to one surface of a glass cloth (manufactured by Asahi Schwebel KK, product number 216L) having a thickness of 0.1 mm using the production line shown in FIG. However, since the viscosity was too high, it could not be discharged from the lip portion and could not be applied.

Therefore, the solvent-free epoxy resin composition obtained by mixing at 130 ° C. for 15 minutes was supplied to a hopper of a die coater heated to 90 ° C., which is a temperature at which the viscosity was such that the composition could be applied. Next, the solvent-free epoxy resin composition in the hopper was discharged from the lip of the die coater so that the time from the start of mixing as the solvent-free epoxy resin composition to the application was 20 minutes, and FIG. Was applied to one surface of a glass cloth (manufactured by Asahi Schwebel KK, part number 216L) having a thickness of 0.1 mm using the production line shown in FIG. A minute was heated to produce a prepreg.

The obtained prepreg was a prepreg with insufficient penetration of the applied epoxy resin composition. That is, the prepreg had no permeation of the epoxy resin composition to the back side of the coated surface, and had a clear difference in front and back.

The melt viscosity at 60 ° C. of the solvent-free epoxy resin composition obtained by mixing at 130 ° C. for 15 minutes is 500,000 cps, and the melt viscosity at 90 ° C. is 10,000.
cps. The rate of increase in melt viscosity when this resin composition is heated and stored at 60 ° C. reaches 50% after storage for 1 hour, and the rate of increase in melt viscosity when heated and stored at 90 ° C. is 50%. Reached after storage for 30 minutes.

Comparative Example 2 Epoxy resin 2 (47 parts by weight) and epoxy resin 3 (18 parts by weight) were melt-mixed at 130 ° C., and tetrabromobisphenol A (35 parts by weight) and dicyandiamide ( 3 parts by weight)
And curing accelerator 3 (0.06 parts by weight)
For 15 minutes to prepare a solventless epoxy resin composition. The dicyandiamide insolubility immediately after the preparation of this resin composition was 76%. Next, this solvent-free epoxy resin composition was supplied to a hopper of a die coater heated to 60 ° C. Next, the solvent-free epoxy resin composition in the hopper was discharged from the lip of the die coater so that the time from the start of mixing as the solvent-free epoxy resin composition to the application was 20 minutes, and FIG. Is applied to one side of a glass cloth (product number 216L, manufactured by Asahi Schwebel Co., Ltd.) having a thickness of 0.1 mm using the production line shown in FIG. I couldn't do that.

Then, the solvent-free epoxy resin composition obtained by mixing at 130 ° C. for 15 minutes was supplied to a hopper of a die coater heated to 80 ° C., which is a temperature at which a viscosity at which coating was possible was obtained. Next, the solvent-free epoxy resin composition in the hopper was discharged from the lip of the die coater so that the time from the start of mixing as the solvent-free epoxy resin composition to the application was 20 minutes, and FIG. Was applied to one surface of a glass cloth (manufactured by Asahi Schwebel KK, part number 216L) having a thickness of 0.1 mm using the production line shown in FIG. A minute was heated to produce a prepreg.

The obtained prepreg was a prepreg with insufficient penetration of the applied epoxy resin composition. That is, the prepreg had no permeation of the epoxy resin composition to the back side of the coated surface, and had a clear difference in front and back.

The melt viscosity at 60 ° C. of the solvent-free epoxy resin composition obtained by mixing at 130 ° C. for 15 minutes was 400,000 cps, and the melt viscosity at 80 ° C. was 8000 cps.
ps. Further, when the resin composition is heated and stored at 60 ° C., the rate of increase in melt viscosity reaches 50% when 1
After storage for a time, the rate of increase in melt viscosity when heated and stored at 80 ° C. reached 50% after storage for 25 minutes.

Comparative Example 3 Epoxy resin 2 (47 parts by weight) and epoxy resin 3 (18 parts by weight) were melt-mixed at 130 ° C., and tetrabromobisphenol A (35 parts by weight), dicyandiamide ( 3 parts by weight)
And curing accelerator 2 (0.20 parts by weight)
For 15 minutes to prepare a solventless epoxy resin composition. The dicyandiamide insolubility immediately after the preparation of this resin composition was 81%. Next, this solvent-free epoxy resin composition was supplied to a hopper of a die coater heated to 60 ° C. Next, the solvent-free epoxy resin composition in the hopper was discharged from the lip of the die coater so that the time from the start of mixing as the solvent-free epoxy resin composition to the application was 20 minutes, and FIG. Is applied to one side of a glass cloth (product number 216L, manufactured by Asahi Schwebel Co., Ltd.) having a thickness of 0.1 mm using the production line shown in FIG. I couldn't do that.

Then, the solvent-free epoxy resin composition obtained by mixing at 130 ° C. for 15 minutes was supplied to a hopper of a die coater heated to 85 ° C., which is a temperature at which a viscosity at which coating was possible. Next, the solvent-free epoxy resin composition in the hopper was discharged from the lip of the die coater so that the time from the start of mixing as the solvent-free epoxy resin composition to the application was 20 minutes, and FIG. Was applied to one surface of a glass cloth (manufactured by Asahi Schwebel KK, part number 216L) having a thickness of 0.1 mm using the production line shown in FIG. A minute was heated to produce a prepreg.

The prepreg obtained was a prepreg with insufficient penetration of the applied epoxy resin composition. That is, the prepreg had no permeation of the epoxy resin composition to the back side of the coated surface, and had a clear difference in front and back.

The melt viscosity at 60 ° C. of the solvent-free epoxy resin composition obtained by mixing at 130 ° C. for 15 minutes was 300,000 cps, and the melt viscosity at 85 ° C. was 10,000.
cps. The rate of increase in the melt viscosity when the resin composition is heated and stored at 60 ° C. reaches 50% after storage for 1.5 hours, and the rate of increase in the melt viscosity when the resin composition is heated and stored at 85 ° C. It reached 50% after 45 minutes storage.

Comparative Example 4 Example 1 was repeated except that the time from when mixing of E1 and M1 was started in the mixer to the time of coating was changed to 4.5 hours by changing the residence time in the hopper. A prepreg was prepared in the same manner. In addition, dicyandiamide insolubility at the time of application of this resin composition was 96%.

The prepreg obtained was a prepreg with insufficient penetration of the applied epoxy resin composition. That is, the prepreg had no permeation of the epoxy resin composition to the back side of the coated surface, and had a clear difference in front and back. In addition, since the solvent-free epoxy resin composition was thickened in the hopper, the discharge amount was not stable, and the resin amount of the prepreg was uneven.

The melt viscosity at 60 ° C. in the initial state (at the time of mixing for 5 minutes with a mixer) of the solvent-free epoxy resin composition in which E1 and M1 were mixed was 6000 cps, and the melt viscosity at 60 ° C. was 4.5 hours. The melt viscosity was 11,000 cps when stored under heating.

(Comparative Example 5) E1 and M1 were mixed with
Mix for 5 minutes while heating to 0 ° C. to prepare a solvent-free epoxy resin composition, and then supply the solvent-free epoxy resin composition to a hopper of a die coater heated to 105 ° C., and the residence time in the hopper Was adjusted to prepare a prepreg in the same manner as in Example 1 except that the time from the start of mixing of E1 and M1 with the mixer to the application was set to 2.5 hours. In addition, the dicyandiamide insolubility at the time of application of this resin composition was 92%.

The prepreg obtained was a prepreg with insufficient penetration of the applied epoxy resin composition. That is, the prepreg had no permeation of the epoxy resin composition to the back side of the coated surface, and had a clear difference in front and back.

The melt viscosity at 60 ° C. of the initial state of the solvent-free epoxy resin composition obtained by mixing E1 and M1 (at the time of mixing for 5 minutes with a mixer) was 6000 cps.
The melt viscosity at 105 ° C. is 200 cps, and the melt viscosity at 60 ° C. at the time of application (the time from the start of mixing of E1 and M1 by the mixer to the time of application is 2.5 hours) is 25,000 cps at 105 ° C. Melt viscosity is 10,000
cps.

As described above, in Comparative Example 5, only a prepreg insufficiently penetrated by the epoxy resin composition due to thickening was obtained even when the time until application was 2.5 hours.

[0077]

In the method for producing a prepreg according to the present invention, a solvent-free epoxy resin composition is applied to one surface of a glass substrate by a die coater and then heated to produce a prepreg. The resin composition can be uniformly applied and impregnated on the base material in a fixed amount, and also obtained as a solventless epoxy resin composition by heating an epoxy resin and a phenol compound at 100 to 180 ° C. and melt-mixing. A primary mixture, dicyandiamide, and a curing accelerator,
Since the liquid solvent-free epoxy resin composition obtained by mixing at a temperature of 90 ° C. or less within 4 hours before application to the glass substrate is used, the liquid solvent-free epoxy resin at the time of application to the glass substrate is used. An increase in the viscosity of the resin composition is suppressed. Therefore, according to the method for producing a prepreg according to the present invention, it is possible to obtain a prepreg in which the epoxy resin composition is uniformly applied and impregnated, there is no difference in front and back in appearance, and the epoxy resin composition has good penetration. .

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a production line used in an embodiment of a method for producing a multilayer wiring board of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yukihiro Hatta 1048 Kadoma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works, Ltd. References JP-A-6-143446 (JP, A) JP-A-2-145676 (JP, A) JP-A-8-259670 (JP, A) JP-A-57-83535 (JP, A) JP-A Sho 58-128847 (JP, A) JP-A-59-114026 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08J 5/24 CA (STN) REGISTRY (STN)

Claims (6)

(57) [Claims] 1. A compound having two or more epoxy groups per molecule and having a viscosity at 25 ° C. of 1,000 to 30,000 cps.
An epoxy resin (a) containing 50% by weight or more of a liquid epoxy resin, a phenol compound (b) having two or more phenolic hydroxyl groups per molecule, dicyandiamide (c), and a curing accelerator (d) A prepreg manufacturing method of applying a solvent-free epoxy resin composition containing, on a die coater to one surface of a glass substrate, and then heating to manufacture a prepreg, as a solvent-free epoxy resin composition, The above-mentioned epoxy resin (a) and the above-mentioned phenol compound (b) are heated at 100 to 180 ° C. and melt-mixed, and a primary mixture obtained, the above-mentioned dicyandiamide (c), the above-mentioned curing accelerator (d Is a method for producing a prepreg using a solventless epoxy resin composition obtained by mixing at a temperature of 90 ° C. or less within 4 hours before application to a glass substrate. And said primary mixture, dicyandiamide (c), of dicyandiamide solventless epoxy resin composition obtained by mixing a curing accelerator (d) 9
A method for producing a prepreg, wherein 0% by weight or more is dispersed as dispersed particles in a solventless epoxy resin composition. 2. When mixing the primary mixture, dicyandiamide (c), and curing accelerator (d), both dicyandiamide (c) and curing accelerator (d) or dicyandiamide (c) and curing acceleration are mixed. Each of the agents (d) is independently an epoxy resin having a softening point of 90 ° C. or less and having one or more epoxy groups per molecule or a softening point of 90 or less.
℃ After the premix was mixed with a phenolic compound having one or more phenolic hydroxyl groups per molecule or less, prepreg of claim 1 Symbol mounting characterized by mixing the premix with the primary mixture Manufacturing method. 3. When mixing the primary mixture, dicyandiamide (c) and a curing accelerator (d), one of dicyandiamide (c) and the curing accelerator (d) has a softening point of 90 ° C. or less. An epoxy resin having one or more epoxy groups per molecule or a phenol compound having one or more phenolic hydroxyl groups per molecule having a softening point of 90 ° C. or less is used as a premix. the process according to claim 1 Symbol placement of the prepreg, characterized in that. 4. When mixing the primary mixture, dicyandiamide (c) and a curing accelerator (d), the dicyandiamide (c) is mixed with one or more epoxy groups per molecule having a softening point of 90 ° C. or lower. An epoxy resin having a softening point of 90 ° C. or less and a phenolic compound having at least one phenolic hydroxyl group per molecule to form a premix, and a dicyandiamide-containing premix kept in a fluidized state, either independently curing accelerator was maintained in a fluidized state (d) or a curing accelerator and (d) inclusions, claim 1, characterized in that it has to mix with the primary mixture to claim 3 The method for producing a prepreg according to the above. 5. A curing accelerator (d) is comprise two or more components, and, of claims 1, characterized in that it contains a phosphorus-based curing accelerator to claim 4 as an essential component A method for producing the prepreg according to any one of the above. 6. The method for producing a prepreg according to claim 1, wherein the curing accelerator (d) contains a compound represented by the following formula as an essential component. However, n in the formula represents an integer of 1 to 4,
m represents an integer of 1 or 2, and R represents an m-valent organic group. Embedded image