JP2000159912A - Prepreg and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide prepreg that hardly causes the problems on blurring and warpage of laminated sheets and its production process. SOLUTION: In the prepreg that is prepared by impregnating the base material with substantially solvent-free thermosetting resin, the thermosetting resin composition layers are made almost equal to each other in their surface thickness on both their front and back faces. In the production of the objective prepreg, the base material is continuously conveyed and the thermosetting resin is supported on the peripheral surface of the coating roller that rolls in the reverse direction to the base-conveying direction to transfer the thermosetting resin from the peripheral surface of the coating roller onto the one face of the base material, whereby the base material is directly coated with the thermosetting resin. In this case, the contact angle of the base material to the coating roller is set to 90 deg. <= contact angle <= 120 deg. and the rolling speed of the coating roller is set to 150-400% of the base material-conveying speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prepreg which does not cause burrs or warpage during molding of a laminate, and a method for producing the same.

[0002]

2. Description of the Related Art A prepreg used for manufacturing a laminated board for a printed wiring board has been prepared by dissolving a thermosetting resin such as an epoxy resin in an organic solvent to form a varnish. It is obtained by impregnating (penetrating) the substrate, removing the heated organic solvent, and making the thermosetting resin B-stage. However, in such a production method, it is necessary to use a large amount of the organic solvent, and it is necessary to remove the large amount of the organic solvent from the base material and then treat the organic solvent. there were.

In order to solve this problem, various measures have been taken to impregnate the substrate with a substantially solvent-free thermosetting resin composition. As one of such ideas,
While continuously transporting the substrate, a substantially solvent-free thermosetting resin composition is carried on the peripheral surface of the application roll rotating in the direction opposite to the transport direction of the substrate, and the application roll A method of directly applying the thermosetting resin composition to the substrate by transferring the thermosetting resin composition from the peripheral surface to one surface of the substrate has been proposed (Japanese Patent Application Laid-Open No. Hei 4-
No. 2,28671). According to this direct coating method, a resin spread uniformly on a coating roll rotating in a direction opposite to the substrate transport direction is applied to the substrate transported at a constant tension from one direction. It is stated that by performing the process, the thermosetting resin can be satisfactorily impregnated into the base material even if it is substantially solvent-free.

However, according to an additional test conducted by the present inventors, it was found that the prepreg obtained by this coating method was liable to cause problems such as fraying and warpage of the laminated plate during molding of the laminated plate. In particular, when the thickness of the base material is increased (for example, when the thickness is 0.18 mm or more in the case of glass cloth), problems such as the above-described burrs and warpage of the laminated board occur frequently.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a prepreg obtained by impregnating a substantially solvent-free thermosetting resin composition into a base material, while preventing the occurrence of the above-mentioned waste and warpage of a laminated board. An object of the present invention is to provide a prepreg and a method for manufacturing the same, which are less likely to cause a problem.

[0006]

Means for Solving the Problems The present inventor has deeply pursued a cause that the prepreg obtained by the above one-side direct coating method is liable to cause problems such as fraying and warping of a laminated board. As a result, the cause of the above-mentioned problem is that the thermosetting resin composition to be impregnated into the base material is substantially solvent-free, and thus tends to be biased toward the coating surface side (with a piece). It was found that the thickness of the thermosetting resin composition on both surfaces was uneven. Scratches occur due to insufficient amount of impregnated resin,
Laminate warpage is caused by an imbalance between the front and back surfaces, but tearing can cause such a problem, and from the results of surface observation of the prepreg, in fact, tearing occurred. .

[0007] This non-uniformity can be solved by the method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. Hei 4-2286.
As described in JP-A-71, the coating by the transfer is
The problem can be solved to some extent by dividing the substrate into two steps, the front side and the back side. However, when the coating line is branched into two systems as described above, the cost of the coating equipment is doubled, the cleaning work is doubled, and a problem arises in terms of resin life. In other words, the thermosetting resin increases in viscosity (resin life) while being transported in the pipe, so that the thermosetting resin easily adheres to the inner wall surface of the pipe, making the coating conditions unstable. This effect cannot be ignored as the piping lengthens, but if two coating lines are used, the effect of this problem becomes complicated and simply cannot be treated.

Further, even if the coating is performed from the front and back surfaces, the above-mentioned nonuniformity cannot be solved at a practical level. That is, when coating on the back side after coating on the front side, the thermosetting resin composition impregnated from the front side with the coating pressure from the back side will be pushed back, and this pushing back action is various. Since it changes delicately in the field, it is not uniform. Therefore, even if the coating conditions on the front and back surfaces are precisely adjusted and controlled, the thickness of the resin composition on both surfaces of the base material is constantly uneven.

[0009] The conclusion reached by the present inventors is that, after all, the unevenness of the resin thickness due to such a cause is better to be solved by one-sided coating instead of two-sided coating. In order to achieve a uniform thickness of the resin composition by variously adjusting, various studies were conducted and experiments were repeated. Then, it was confirmed that this problem could be solved by adjusting the ratio of the winding angle of the base material to the application roll and the rotation speed of the application roll to the base material transport speed, and completed the present invention.

Therefore, the prepreg according to the present invention is a prepreg comprising a substrate impregnated with a substantially solvent-free thermosetting resin composition, wherein the thickness of the thermosetting resin composition layer on the surface of the substrate is both It is characterized by being substantially equal on the surface. Further, the method for producing a prepreg according to the present invention is a method for continuously transporting a base material, and a substantially solvent-free thermosetting resin on the peripheral surface of an application roll rotating in a direction opposite to the direction of transport of the base material. The thermosetting resin composition is directly applied to the base material by transferring the thermosetting resin composition from the peripheral surface of the application roll to one surface of the base material while holding the composition. The wrapping angle of the base material with respect to the application roll is 9
It is characterized in that the rotation speed of the application roll is set to 150 to 400% of the transport speed of the base material while the rotation speed is set to more than 0 degree and 120 degrees or less.

[0011]

Embodiments of the present invention will be described below. In the prepreg 1 ′ obtained by the conventional direct coating method, as shown in FIG. 1B, the surface resin composition 11 was attached to one side of the base material 12. On the other hand, in the prepreg 1 according to the present invention, as shown in FIG.
The layer thickness 11a on the front side and the layer thickness 11b on the rear side of
The layer thickness 11b on the back side is ±
It falls within the range of 5%, and the thickness of the resin composition layer on the front and back surfaces is extremely uniform compared to the case where the prepreg 1 'obtained by the conventional direct coating method exceeds ± 20%. . In addition, 12a is a base material thickness.

The prepreg according to the present invention is preferably obtained by the production method of the present invention described below. FIG. 2 shows an embodiment of the method for producing a prepreg according to the present invention, and FIG. 3 shows a step of applying a thermosetting resin composition in this production method. As shown in FIG. 2, the base material 12 wound in a roll shape is continuously fed out from the base material feeding means 2, guided by a guide roll (not shown), and continuously conveyed. The base material 12 becomes the prepreg 1 through the coating device 3, and is heated in the heating furnace 4 to form the thermosetting resin composition 1.
1 is B-staged and wound by prepreg winding means 5. The coating device 3 includes a coating roll 31 and a coating unit 32. The coating unit 32 includes a nozzle 33 that discharges the substantially solvent-free thermosetting resin composition 11, and a uniformity that spreads the thermosetting resin composition 11 discharged to the coating roll 31 on the peripheral surface of the coating roll 31. Roll 34
And The application roll 31 is in a direction opposite to the transport direction of the substrate 12 and is 150 to 400% of the transport speed of the substrate 12
, Preferably at a speed of 270 to 320%. The arrows in FIGS. 2 and 3 indicate the substrate transport direction and the roll rotation direction. If the transport speed of the substrate 12 is less than 150%, the rotation of the thermosetting resin composition becomes insufficient, and the thickness of the thermosetting resin composition layer becomes unbalanced on the coating side, resulting in 400
%, The turn of the thermosetting resin composition becomes excessive, and a thick imbalance occurs on the side of the thermosetting resin composition layer opposite to the coating side.

As shown in FIG. 3, the substrate 12 is applied so as to be wound around a coating roll 31 within a certain circumferential angle range. The winding angle α of the substrate 12 is set to be more than 90 degrees and not more than 120 degrees, preferably in the range of 95 to 105 degrees. The winding angle α is perpendicular to the tangent to the coating roll 31 on the upstream side of the flow of the substrate 12 and perpendicular to the tangent to the imaginary line passing through the center of the coating roll 31 and the coating roll 31 on the downstream side.
Is the circumferential angle between the imaginary line passing through the center of the circle. When the winding angle α is 90 degrees or less, the rotation of the resin composition is insufficient, and when the winding angle α exceeds 120 degrees, the base material tension increases and coating becomes difficult. 31a is a seepage part.

In the method for producing a prepreg according to the present invention, the thickness of the thermosetting resin composition layer on the front and back surfaces of the base material in the prepreg is controlled by controlling the winding angle α and the reverse rotation speed of the coating roll. it can. Note that B
Although the thermosetting resin composition slightly flows due to heating for staging, the flow does not occur enough to change the thickness of the resin composition layer on the front and back surfaces of the base material, so the thickness of the resin composition layer on the front and back surfaces of the base material May be measured before and after the B stage.

In the method of the present invention, the coating unit 32 may be constituted by a die coater system, a roll coater system or the like. The thermosetting resin composition 11 has a viscosity of 1
It is preferably about 500 cps, more preferably around 100 cps. The air permeability of the substrate 12 has a pore area of 100 to 400.
About 0 μm ² is preferable. The transport speed of the substrate 12 is 1 to 3
Preferably, the tension is 0 m / min and the tension is about 5 to 30 kgf / 500 mm.

Incidentally, solid curing agents such as dicyandiamide have low compatibility with epoxy resins. This point is not a problem when an organic solvent is used as in the prior art, but when the solvent is substantially free as in the present invention, uneven impregnation of the base material, a decrease in reactivity of the epoxy resin composition, and uneven curing are caused. ,
Problems such as whitening of the laminate may occur. Therefore, in order to enhance the solubility of the solid curing agent, it is preferable to heat the application roll 31 to, for example, a surface temperature of about 100 to 200 ° C. It is also preferable to heat the thermosetting resin composition to about 100 to 140 ° C.

In the present invention, the thermosetting resin composition 1
No. 1 is prepared as follows using the following materials. As the substrate 12, glass cloth is preferably used, but paper, nonwoven fabric, and the like can also be used. The type of the thermosetting resin is not particularly limited, and an epoxy resin is preferably used. Hereinafter, a case where an epoxy resin is used as the thermosetting resin will be described.

The epoxy resin has two or more epoxy groups in one molecule, and comprises bisphenol A
Examples thereof include a type epoxy resin, a brominated bisphenol A type epoxy resin, a cresol novolak type epoxy resin, and a phenol novolak type epoxy resin, but are not particularly limited thereto. In particular, it is preferable to use an epoxy resin which is liquid at room temperature or has a low melting point, since the penetration into the base material and the uniformity of the prepreg are improved.

In the present invention, the type of curing agent for the epoxy resin is not particularly limited, but dicyandiamide can be used as one of the preferable ones. By using this dicyandiamide, the epoxy resin composition has high adhesive strength and high heat resistance. And good electrical characteristics.
Dicyandiamide is incompatible or hardly compatible with the epoxy resin.For this reason, when dicyandiamide is contained in the epoxy resin composition, when the epoxy resin composition is applied to one surface of the base material and impregnated, It is difficult for dicyandiamide to penetrate into the inside of the base material or the surface side opposite to the application side, and may adhere to the surface of the base material and become unevenly distributed. As a result, the curability of the epoxy resin composition decreases. May cause measling. Therefore, in the present invention, it is preferable to use dicyandiamide having an average particle size of 15 μm or less. If the average particle diameter is larger than the above, the above problem may occur. The average particle size of dicyandiamide is preferably smaller in consideration of the ease of infiltration into the base material, but the average particle size of dicyandiamide is 0.05 μm or more in consideration of controllability of the reaction with the epoxy resin. Is preferred.

In the present invention, as another curing agent of the epoxy resin, a phenolic curing agent having three or more hydroxyl groups in one molecule can be used. This phenolic curing agent is active hydrogen (hydroxyl group) reactive with epoxy resin.
In one molecule, and dicyandiamide has heat solubility in this phenolic curing agent. Therefore, by blending dicyandiamide and a phenolic curing agent with an epoxy resin to prepare an epoxy resin composition, the phenolic curing agent can be cured at a relatively low temperature (about 100 ° C or higher) below the melting point (200 ° C) of dicyandiamide. To dissolve the dicyandiamide, thereby increasing the solubility (compatibility) of the dicyandiamide in the epoxy resin composition. Therefore, when penetrating the epoxy resin composition into the substrate, dicyandiamide can be prevented from adhering to the surface of the substrate and unevenly distributed, and the dicyandiamide is uniformly impregnated into the substrate together with the epoxy resin. In addition, it is possible to prevent unevenness of reactivity and curing of the epoxy resin (composition) from occurring, to prevent measling from occurring in the laminate, and to prevent deterioration of properties such as strength of the laminate. Can be

If the phenolic curing agent has an average of less than 3 hydroxyl groups in one molecule, the cured product of the epoxy resin composition is inferior in heat resistance and the like, resulting in uneven curing and physical properties of products such as laminates. May occur. If the phenolic curing agent has an average of more than 50 hydroxyl groups in one molecule, the cured product of the epoxy resin composition may be hard and brittle, but this is not a serious problem. Accordingly, the phenolic curing agent preferably has an average of 50 or less hydroxyl groups in one molecule.

Examples of the phenolic curing agent satisfying such conditions include phenol novolak compounds, and more specifically, phenol novolak, cresol novolak, bisphenol A novolak, and dicyclopentadiene-containing phenol novolak (diphenyl phenol). Cyclopentadiene copolymerized phenol novolak). In addition to the phenol novolak compound, a trifunctional phenol compound represented by the following formula (1) can be used as a phenol curing agent satisfying the above conditions.

[0023]

Embedded image

(Where R 1 and R 2 are each C _n H
_{2n + 1} , where n = 0, 1, 2, 3, 4 ...
・ It is. When phenol novolak is used, the electrical insulation and heat resistance of the laminate can be increased. When cresol novolak is used, its reactivity is lower than that of other phenol novolaks, so that the stability of the epoxy resin composition during heating (such as during impregnation) and the storage stability of the B-staged prepreg can be increased. .

When bisphenol A novolak is used,
Since the reactivity is lower than other phenol novolaks like cresol novolak, the stability of the epoxy resin composition when heated (during impregnation, etc.) and the storage stability of the B-staged prepreg can be increased, In addition, since it is less oxidized during heating (such as during mixing with an epoxy resin) than phenol novolak and cresol novolak, the epoxy resin composition and the prepreg are less colored and discolored, resulting in a better appearance.

When dicyclopentadiene-containing phenol novolak is used, its reactivity is lower than that of other phenol novolaks, like cresol novolak.
The storage stability of the staged prepreg can be increased, and the cured product of the epoxy resin composition has a lower hygroscopic property than the case of using phenol novolak, cresol novolak, and bisphenol A novolak, and the epoxy resin composition Since the toughness of the cured product becomes excellent, the moisture absorption resistance and toughness of the laminate can be increased.

When the trifunctional phenolic compound of the above formula (1) is used, the glass transition temperature (Tg) of the cured product of the epoxy resin composition becomes higher than that of other phenolic compounds, so that the The heat resistance can be improved. In the present invention, a flame retardant, an additive for improving quality and a curing accelerator may be added as necessary. As the flame retardant, it is preferable to use a reactive flame-retardant phenol, particularly, tetrabromobisphenol A having two active hydrogens in one molecule which reacts with the epoxy group of the epoxy resin. An epoxy resin composition having a low melting point can be obtained while improving and securing the flame retardancy of the composition. Examples of the curing accelerator include, but are not limited to, tertiary amine accelerators, imidazoles, and phosphorus accelerators.

The preparation of the epoxy resin composition is performed, for example, as follows. First, the epoxy resin, a phenolic compound, and other materials are mixed at a temperature of about 130 ° C. Thereafter, the melt viscosity of the epoxy resin becomes 1000
Cool until it reaches about 0-20,000 cps, then
Dicyandiamide and a curing accelerator are added and mixed to prepare a solventless epoxy resin composition. In the epoxy resin composition thus prepared, with respect to one epoxy equivalent of all epoxy resins in the epoxy resin composition,
The mixing ratio of each curing agent is adjusted such that the hydroxyl equivalent from dicyandiamide (active hydrogen equivalent) becomes 0.7 to 0.2 equivalent and the hydroxyl equivalent from phenolic curing agent becomes 0.7 to 0.1 equivalent. It is preferable to contain them. If the hydroxyl equivalent derived from dicyandiamide exceeds 0.7 equivalent, the number of active hydrogens in dicyandiamide (the blending amount of dicyandiamide) increases, and dicyandiamide penetrates into the inside of the base material or the surface side opposite to the coating side. And it may adhere to the surface of the base material and be unevenly distributed. Further, when the hydroxyl equivalent derived from dicyandiamide is less than 0.2 equivalent, the number of active hydrogens (blended amount of dicyandiamide) of dicyandiamide is reduced, and the electric insulation performance of the epoxy resin composition (laminate) by dicyandiamide is improved. There is a possibility that effects such as improvement in the adhesiveness of the epoxy resin composition (prepreg) may not be easily obtained.

If the hydroxyl equivalent derived from the phenolic curing agent exceeds 0.7 equivalent, the number of active hydrogens of dicyandiamide (blended amount of dicyandiamide) becomes relatively small, and the epoxy resin composition by dicyandiamide (laminate) There is a possibility that it may be difficult to obtain effects such as improvement of the electrical insulation performance and adhesion of the epoxy resin composition (prepreg). Further, if the hydroxyl equivalent derived from the phenolic curing agent is less than 0.1 equivalent, the number of active hydrogens of dicyandiamide (combined amount of dicyandiamide) becomes relatively large, and dicyandiamide is opposite to the inside of the base material or the coating side. It hardly penetrates to the side surface side, and may adhere to the surface of the base material and be unevenly distributed. More preferred amounts of the dicyandiamide and the phenolic curing agent are such that the hydroxyl equivalent of dicyandiamide is 0.5 to 0.3 equivalent, and the hydroxyl group of the phenolic curing agent is based on 1 epoxy equivalent of all epoxy resins in the epoxy resin composition. The equivalent is to be 0.5 to 0.2 equivalent, which is an optimum amount for solving the above-mentioned inconvenience and attaining both good physical properties of the laminated board after molding.

In the epoxy resin composition, a phenolic compound having an average of less than three active hydrogens in one molecule that reacts with the epoxy group of the epoxy resin (for example, tetrabromobisphenol A compounded as a reactive flame retardant or the like) When used, it corresponds to (reacts) the active hydrogen of a phenolic compound having less than three active hydrogens on average in one molecule.
The epoxy group is excluded from the one epoxy equivalent of the epoxy resin, and the hydroxyl equivalent of dicyandiamide and phenolic curing agent is calculated.

Considering that dicyandiamide is dissolved in the phenolic curing agent and the epoxy resin, the amount of the phenolic curing agent is preferably set to 5 to 13% by weight based on the total amount of the epoxy resin composition. If the blending amount of the phenolic curing agent is less than 5% by weight, the solubility (compatibility) of dicyandiamide in the epoxy resin composition even when heated to 100 ° C. or more before applying the epoxy resin composition to the base material. If the amount of the phenolic curing agent exceeds 13% by weight, the amount of the dicyandiamide is relatively small, and the electric power of the epoxy resin composition (laminated plate) by the dicyandiamide may be reduced. There is a possibility that it may be difficult to obtain effects such as improvement in insulation performance and improvement in adhesiveness of the epoxy resin composition (prepreg).

After the solvent-free epoxy resin composition is prepared as described above, a sheet-like reinforcing substrate made of fiber, such as glass cloth or non-woven glass fabric, is coated on one side thereof as described above. From 60 to 2 epoxy resin composition
By applying the epoxy resin composition at 60 g / m ² and then penetrating (impregnating) the epoxy resin composition by heating the base material, the epoxy resin composition impregnated on the base material is semi-cured to form a B stage, The prepreg of the present invention can be manufactured.

[0033]

The results of Examples of the present invention and Comparative Examples outside the scope of the present invention will be shown below, but the present invention is not limited to the following Examples. A substantially solvent-free thermosetting resin composition was prepared as follows. A cresol novolac epoxy resin having an epoxy equivalent of 210 (Dainippon Ink and Chemicals, Inc.) per 60 parts by weight of a bisphenol A epoxy resin having an epoxy equivalent of 190 (trade name “Epicoat 828” manufactured by Yuka Shell Epoxy Co., Ltd.) (EPICLON N680), 10 parts by weight, and 30 parts by weight of brominated phenol (tetrabisphenol A (reagent), number average molecular weight 544, theoretically active hydrogen equivalent (reaction equivalent to one epoxy group) = 272 g / eq) And 13 parts
The mixture was heated and mixed at 0 ° C. to obtain an epoxy resin A.

To 100 parts by weight of this epoxy resin A (the number of epoxy groups is 0.25), 1.8 parts by weight of dicyandiamide (the number of active hydrogens is 0.086)
And bisphenol A type novolak resin 12.0
Parts by weight (the number of active hydrogens becomes 0.10) as a curing accelerator and 0.06% of 2-ethyl-4-methylimidazole.
Parts by weight were blended and mixed to prepare a substantially solvent-free thermosetting resin composition (melt viscosity at 135 ° C. and 50 cps).

Dicyandiamide: reagent, average particle size 150
μm, number average molecular weight 84, theoretical active hydrogen equivalent = 21 g /
eq, the number of active hydrogens in one molecule is 4. Bisphenol A type novolak resin: manufactured by Dainippon Ink and Chemicals, Inc., trade name "Phenolite VH4150",
Theoretical active hydrogen equivalent = about 120 g / eq, softening point = about 85
The solubility at 100 ° C. and the temperature of 100 ° C. is 100%, and the number of active hydrogens in one molecule is 10 to 3;

As a substrate, a glass cloth having a thickness of 0.18 mm (trade name “7628H25” manufactured by Asahi Schubel Co., Ltd.)
8 ", a pore area of 200 to 1200 μm ² ), and was continuously conveyed at a speed of 1.8 m / min and a tension of 15 kgf / 500 mm. The above thermosetting resin composition heated to 130 ° C. is supplied to an application roll having a surface temperature maintained at 135 ° C., and is applied to one surface (lower surface) of the substrate in an amount of 170 g / m ² , and is a non-contact type. A prepreg was obtained by heating to about 180 ° C. in a heating furnace to form a B stage.

At this time, the change in the thickness of the thermosetting resin composition layer on the surface of the substrate was observed while the winding angle α of the substrate was kept constant at 100 degrees and the peripheral speed of the application roll was changed. As a result, at a peripheral speed of 6 m / min, the front and back surfaces are almost uniform (2% difference between the front and back surfaces). At a peripheral speed of 1.8 m / min, the rotation is insufficient, and the lower surface side is thick and one-sided (15% difference between the front and back surfaces). At 8 m / min, the rotation is excessive, the upper surface is thick and the surface is still loose (the difference between the front and back surfaces is 30).
%).

When the winding angle α of the base material was 80 degrees, no matter how the peripheral speed was adjusted, the rotation was insufficient, and the lower surface side was thick and had a single-sided (a difference between the front and back surfaces was 20%). Substrate winding angle α
However, at 130 degrees, no matter how the peripheral speed was adjusted, the substrate tension increased, bending occurred, and the product became defective. Usually, the coating width on the peripheral surface of the application roll needs to be set narrower than the base material width, and therefore, from the difference in frictional resistance between both ends of the base material that protrudes the coating width and the inside of the base material coating width, Although both ends of the base material tend to be slightly pulled in a portion within the coating width of the base material, when the winding angle of the base material is increased, the pulling phenomenon is increased, and finally a defective product is caused. Curving refers to such a phenomenon.

[0039]

In the prepreg according to the present invention, the thickness of the thermosetting resin composition layer on the surface of the base material is substantially equal on both surfaces, so that it is difficult for the prepreg to be formed with a curl or warp during molding of the laminate. According to the method for producing a prepreg according to the present invention, such a prepreg is easily and reliably obtained. According to this method, the thickness of the resin composition on the front and back surfaces of the base material can be varied by changing and adjusting the peripheral speed of the application roll.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a prepreg (a) according to the present invention in comparison with a conventional prepreg (b).

FIG. 2 is a schematic explanatory view showing one embodiment of a method for producing a prepreg according to the present invention.

FIG. 3 is an explanatory view showing a coating step in FIG. 2;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 prepreg 3 coating device 4 heating furnace 11 thermosetting resin composition 11 a thickness of resin composition on base material side 11 b thickness of resin composition on base material back side 12 base material

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hideo Fujinaka 1048 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Works, Ltd. (72) Inventor Toshihiro Iji 1048 Kazuma Kadoma, Kadoma City, Osaka Matsushita Electric Works F Terms (Reference) 4F072 AA04 AA07 AB09 AB29 AD27 AD28 AD29 AE02 AG03 AH04 AH12 AH26 AL13 4F205 AA36 AA37 AA39 AD16 AM32 AM35 AR07 AR09 HA06 HA23 HA33 HA37 HA47 HB02 HC05 HC16 HE06 HF01 HF05 HF23 HK02 HK19 HK19

Claims (2)

[Claims] 1. A prepreg comprising a substrate impregnated with a substantially solvent-free thermosetting resin composition, wherein the thickness of the thermosetting resin composition layer on the surface of the substrate is substantially equal on both surfaces. And prepreg. 2. The method according to claim 1, wherein the substrate is continuously conveyed, and a substantially solvent-free thermosetting resin composition is carried on a peripheral surface of an application roll rotating in a direction opposite to the direction of conveyance of the substrate. And
By transferring the thermosetting resin composition from the peripheral surface of the coating roll to one surface of the substrate, a method for producing a prepreg including a step of directly applying the thermosetting resin composition to the substrate. The winding angle of the base material with respect to the application roll is set to more than 90 degrees and equal to or less than 120 degrees, and the rotation speed of the application roll is set to 150 to 400 of the base material conveyance speed.
%. A method for producing a prepreg, wherein the prepreg is set to%.