JPH09225938A - Method and device for manufacturing prepreg - Google Patents

Abstract

PROBLEM TO BE SOLVED: To impregnate a fiber material with a resin liquid in a good manner and manufacture a material with extremely small number of foams by applying the resin liquid on one face side of a sheet-shaped base, heating the base from the opposite face side at the temperature lower than the boiling point of a solvent used for the resin liquid and then heat drying the resin impregnated sheet-shaped base. SOLUTION: A sheet-shaped base, for example, a glass cloth 1 is unwound, passed through a guide roll 8a and transferred to a coating device 4 formed of a supporting stand 4b and a coater 4a such as a coater roll or a doctor knife. Then a resin liquid feed device 2 such as a nozzle is used on the upper face side of the coater 4a, and a resin liquid, for example, an epoxy resin liquid 3a is applied. The glass cloth 1 with one face side coated with the resin liquid 3a is transferred immediately to a heating device 5, and heated by hot air of atmospheric temperature lower than the boiling point of a solvent used for the resin liquid 3a from the lower side face, and then both faces of the glass cloth are heat dried by the given atmospheric temperature by a heat drying device 6 to manufacture a prepreg.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a fibrous material such as paper or cloth used for manufacturing an electric insulating board such as a substrate of a printed wiring board for industrial equipment or electronic equipment, or a laminated board such as a decorative board. The present invention relates to a method for manufacturing a prepreg obtained by impregnating a sheet-shaped base material with a resin liquid and an apparatus for the same.

[0002]

2. Description of the Related Art Conventionally, when a sheet-shaped base material made of a fibrous material is impregnated with a resin liquid, the sheet-shaped base material is immersed in the resin liquid and passed through the resin liquid to impregnate the sheet-shaped base material with the resin liquid. The operation is performed, but at this time it is common that the air bubbles between the fibers of the sheet-shaped substrate do not escape and the air bubbles remain in the prepreg. Voids are often generated.
In order to prevent generation of voids and deterioration of electrical characteristics and appearance, it is necessary to carry out lamination molding at high pressure. However, a laminated plate such as an electric insulating plate and a decorative plate obtained by laminating and molding at such a high pressure has problems that the dimensional stability is deteriorated and that the laminated plate is warped or twisted.

In order to obtain a laminated plate having excellent dimensional stability and small warpage and twist, it is necessary to carry out laminating and molding at a low pressure. However, when laminating and molding at such a low pressure, voids do not occur in the laminated plate. It is necessary to use a prepreg in which almost no air bubbles remain. As a method of obtaining a prepreg in which almost no air bubbles remain, there is a method of immersing a sheet-shaped base material in a resin liquid for a long time (about 10 minutes or more) so that the resin liquid is impregnated into the fiber material of the sheet-shaped base material. But,
It is impractical because the production efficiency is extremely poor and the equipment becomes long. Especially in the case of high-concentration resin liquid, it is almost impossible. Further, there is a method in which an ultrasonic oscillator is attached to a resin impregnation tank filled with a resin liquid, and the resin liquid is ultrasonically vibrated to increase the impregnation property of the resin liquid into the sheet-shaped substrate due to the vibration of the substrate and the resin liquid. Although proposed, ultrasonic vibration causes the temperature of the resin liquid to rise and the solvent in the resin liquid evaporates, so that the viscosity of the resin liquid sharply increases and the impregnation property is deteriorated. In order to prevent this, it is necessary to constantly add a solvent to keep the resin liquid at a constant concentration, but there is a problem that a viscosity adjusting device is required and that the addition of a solvent increases the cost.

[0004]

SUMMARY OF THE INVENTION The present invention provides a high-concentration resin liquid (for example, 55% by weight) in the conventional prepreg manufacturing method.
When the above-mentioned) is impregnated into a sheet-like base material made of a fibrous material, various examinations have been made in order to solve the problem that a large amount of air bubbles remain in the fibrous material, resulting in a prepreg. By improving the impregnation of the resin material into the fibrous material of the sheet-shaped base material and performing it uniformly, a prepreg with very few bubbles in the sheet-shaped base material made of the fibrous material even when a high-concentration resin liquid is used. It is to provide a resin liquid impregnation method to be obtained and an apparatus for optimally implementing the method.

[0005]

According to the present invention, a sheet-like base material made of a fibrous material is impregnated with a resin liquid and then dried to produce a prepreg.
After coating the resin liquid on one side of the sheet-shaped substrate, in order to lower the viscosity of the resin liquid and to impregnate the inside of the fibrous material of the sheet-shaped substrate, at a temperature lower than the boiling point of the solvent used for the resin liquid. The resin-impregnated sheet-shaped substrate is heated and dried by heating from the side opposite to the surface coated with the resin liquid and then evaporating the solvent contained in the resin liquid and, if necessary, semi-curing the resin. The present invention relates to a method for manufacturing a prepreg, which comprises: That is, the prepreg manufacturing method of the present invention comprises a coating step of applying a resin liquid on one side of a sheet-shaped base material made of a fibrous material, a heating step of heating the sheet-shaped base material that has gone through the step, and a heating / drying step. This is an essential step.

Further, depending on the type and properties of the sheet-shaped base material made of the fibrous material and the resin liquid used for the sheet-shaped base material, the amount of resin adhering to the predetermined amount can be satisfied only by the step of applying it to one side of the sheet-shaped base material. May not be. In this case, after the heating step, a coating amount adjustment step for continuously adjusting the resin coating amount is added, and then the resin liquid applied first and the resin liquid applied for adjusting the coating amount are heated and dried. Provide a drying process. The resin-adhesion-amount adjusting step may be performed only on the surface opposite to the surface applied to impregnate the resin liquid first, or from both surfaces. The prepreg can be selected according to the required quality, but the former is preferable in consideration of the cost of the apparatus and the balance of the amount of adhesion on both sides. In addition,
The resin adhesion amount adjusting step does not need to be continuous with the preceding step, and may be carried out after winding once, but it is preferable because a winding device and man-hours are required. There is no.

On the other hand, the prepreg manufacturing apparatus of the present invention for carrying out such a method is an apparatus for applying a resin liquid to a sheet-shaped base material made of a fiber material from one side, and a sheet-shaped base material impregnated with the resin liquid for the resin liquid. The sheet-shaped substrate to be used and the resin liquid to be impregnated, which are configured so as to sequentially pass through a device for heating from the side opposite to the surface coated with and a device for heating and drying the sheet-shaped substrate impregnated with the resin liquid. Depending on the type and properties of the prepreg, a resin amount adjusting device is further installed in front of the heating and drying device.

Examples of the sheet-like base material made of the fiber material used in the present invention include glass fiber base materials such as glass cloth, glass non-woven cloth and glass paper, as well as woven cloth, non-woven cloth and metal made of paper, synthetic fiber and the like. Examples thereof include woven fabrics and mats made of fibers and carbon fibers, and the raw materials for these base materials may be used alone or as a mixture. A resin liquid is impregnated into these sheet-shaped base materials and dried to produce a prepreg. As the resin liquid used in the present invention, generally, an epoxy resin, a polyimide resin, and a modified resin thereof are preferably used, but other resins such as a thermoplastic resin and a natural resin are also used. It is not limited to them. Further, a filler, a colorant and a reinforcing material can be blended, and aluminum hydroxide, silica, talc, calcium carbonate and the like can also be blended appropriately as necessary within the range not deviating from the object of the present invention.

The resin liquid thus obtained is mixed with a solvent to adjust its viscosity so that it can be easily impregnated into a sheet-like base material made of a fibrous material. Generally, the solid content is adjusted to about 50% and stored in an impregnation tank, and the air in the fiber material is replaced with the resin solution by passing the sheet-shaped base material through the resin solution to perform impregnation. ing. If the solid content exceeds 55%, the viscosity of the resin liquid becomes high and the impregnating property of the resin liquid into the fiber material decreases,
It is difficult to replace the air in the fibrous material, and the prepreg can be obtained in which air bubbles are dried without being sufficiently removed, and a large amount of air bubbles remain. Usually, even if the solid content becomes high, the resin liquid is heated to reduce the viscosity.However, if the resin liquid contains a low melting point solvent, the solvent gradually evaporates and impregnates. It becomes difficult to control the application conditions in the bath. Therefore, a method of heating at a temperature below the boiling point using a high-boiling solvent is used, but if the temperature is raised more than necessary, the solvent will easily evaporate. It Even under these conditions, the solvent gradually evaporates, increasing the concentration,
In order to increase the viscosity, a resin liquid concentration control device and a viscosity control device are attached and a solvent is appropriately added. This is contrary to the purpose of reducing the cost of raw materials by using a high concentration resin liquid. INDUSTRIAL APPLICABILITY The present invention provides a prepreg which has the same or better impregnation property as the case of using a conventional low-concentration resin liquid even when a resin liquid having a solid content of 55% or more is used, and has few voids even after a heating and drying step. It is a thing.

The steps of the present invention will be sequentially described below. (Resin liquid coating process) High-concentration resin liquid is not stored in the impregnation tank and the sheet-shaped substrate is immersed in it, but the required amount of resin liquid is supplied to the sheet-shaped substrate and applied from one side. By this, volatilization of the solvent from the resin liquid can be suppressed, and the high-concentration resin liquid can be maintained at a constant concentration and viscosity. The concentration of the resin liquid is about 50% by weight in the conventional method as described above, but in the present invention, it may be the same as in the conventional method,
It is preferably about 55 to 70%. With such a high concentration, the amount of solvent can be reduced.

(Warming step) In the step of heating the sheet-shaped base material coated with the high-concentration resin liquid to lower the viscosity of the resin liquid and to easily replace the air in the fiber material. is there. When heated at a temperature higher than the boiling point of the solvent used for the resin liquid, sudden concentration increase occurs due to the sudden boiling of the solvent, impregnating property of the resin liquid is extremely lowered, and defoaming is not possible and a large amount of the resin liquid is not formed. Foaming will occur. In order to solve this problem, it is necessary to heat at a temperature lower than the boiling point of the solvent used in the resin liquid. The temperature is preferably 20 ° C. or more lower than the boiling point of the solvent. Further, since the effect of lowering the viscosity is small even if the temperature is too low, it is preferably at least 50 ° C or higher. Furthermore, if the temperature of the resin liquid rises before the sheet-shaped substrate when heated from the surface coated with the resin liquid, the sheet-shaped substrate will still be at a lower temperature even if the resin liquid has a lower viscosity. This lowers the temperature and prevents the viscosity from decreasing and impairs the impregnating property, which is not preferable. Therefore, heating the sheet-shaped substrate from the side opposite to the surface coated with the resin liquid improves the impregnation property. It is possible to heat from both sides, but it is clear that the effect is less than in the method of heating from the side opposite to the side coated with the resin liquid.

The solvent used for the resin liquid preferably has a high boiling point, but for those having a temperature of higher than 160 ° C., the solvent contained in the resin liquid is vaporized in the subsequent heating and drying step, and if necessary, the resin is semi-dried. High energy is required to bring the resin into a cured state, which is not preferable. For a solvent with a boiling point of 70 ° C or lower, after being applied to a sheet-shaped substrate, it must be gradually vaporized even at room temperature, and the heating temperature must be 50 ° C or lower to avoid bumping. When it becomes low, the viscosity of the resin liquid is not lowered so much and the impregnation property into the fiber material becomes insufficient, which is not preferable. Therefore, a solvent having a boiling point of 70 to 160 ° C., preferably 100 to 160 ° C. is usually used alone or as a mixture of two or more thereof. Specific examples of preferable solvents include dimethylformamide (boiling point: 153 ° C.) and methyl isobutyl ketone (boiling point: 116).
℃), xylene (boiling point 140 ℃), butyl acetate (boiling point 1
26 ° C.) and propylene glycol monomethyl ether (boiling point 120 ° C.).

(Heating and drying step) In this step, the solvent in the resin liquid is vaporized by heating and drying at a temperature higher than the boiling point of the solvent usually used for the resin liquid, and if necessary, the resin is in a semi-cured state. It is possible to obtain a prepreg made of The heating and drying method may be a conventionally used method and is not particularly limited.

[0014]

An embodiment will be described below with reference to FIGS. However, the present invention is not limited by these examples.

Example 1 A glass cloth 1 of 46 g / m ² was unwound at a speed of 3 m / min, passed through a guide roll 8 a, a support 4 b and a coater roll or a coater 4 a such as a doctor knife. Transferred to. The following epoxy resin liquid 3a was applied on the upper surface of the coater using a resin liquid supply device 2 such as a nozzle in an amount of about 124 g / m ² . The gap between the support base 4b and the coater 4a such as a coater roll or a doctor knife is adjusted to 0.2 mm in advance.

The glass cloth 1 coated with the resin liquid on one surface side is immediately transferred to the heating device 5 and heated from the lower surface side by hot air having an ambient temperature of 120 ° C. for about 1 minute, and then heated by the heating / drying device 6. Both surfaces were heated and dried at an ambient temperature of 180 ° C. for about 1 minute to obtain a prepreg having a resin amount of about 61.5%. <Resin liquid composition> Resin (viscous liquid) Epoxy resin 153.6 parts by weight Solvent Dimethylformamide 98.6 Curing agent Dicyandiamide 3.5 Accelerator imidazole 0.15 Resin liquid solid content approx. 61.5%

Example 2 In this example, 210 g /
The case of a glass cloth of m ² is shown. 3 as in Example 1
The epoxy resin liquid 3a shown in the above table is transferred to the coating device 4 at a speed of m / min and the amount of the epoxy resin liquid 3a shown in the above table is about 214 g / m.
^It was applied in an amount of ² . At this time, the gap between the support base 4b and the coater 4a such as a coater roll or a doctor knife is adjusted to 0.32 mm in advance.

A glass cloth 1 coated with a resin solution on one side
Is immediately transferred to the heating device 5 and the ambient temperature 1
After heating with hot air at 20 ° C. for about 1 minute and 30 seconds, the epoxy resin liquid 3b is applied to the lower surface side with the resin adhesion amount adjusting device 7 including the pressing rolls 7a and 7b and the rotating roll 7c in an amount of about 38 g / m ^2. To do. The epoxy resin liquid 3b in the resin liquid tank 7d is the same as the epoxy resin liquid 3a to be applied first, but may be different and may be appropriately selected as needed. After that, 180 on both sides with the heating and drying device 6.
Drying at ambient temperature of ℃ for about 2 minutes, resin amount about 42.4%
Prepreg was obtained.

The prepregs of Examples 1 and 2 were observed with a 50 × microscope to examine the presence or absence of bubbles in the prepreg. The results are as follows, and the number of voids was extremely small in each case, and the number of voids was significantly smaller than that of the prepreg obtained by the usual impregnation method using the epoxy resin solution having the same composition. <Number of voids in prepreg> Within area of 5.2 mm ² Example 10 Example 2 Approximately 20 to 50 Conventional example 500 to 1000 or more

[0020]

According to the method of the present invention, after the resin liquid is applied to one side of the sheet-like base material made of the fibrous material, it is different from the surface applied with the resin liquid at a temperature lower than the boiling point of the solvent used for the resin liquid. By heating from the other side, it is possible to satisfactorily impregnate the resin liquid into the fiber material by reducing the viscosity of the resin liquid while suppressing the evaporation of the solvent in the resin liquid, It is possible to obtain an extremely small amount of prepreg. Moreover, it is not always necessary to use a vertical dryer as in the conventional case, and a horizontal dryer can also be used, and the capital investment can be suppressed.

[Brief description of drawings]

FIG. 1 is a schematic side view showing one embodiment of the present invention.

FIG. 2 is a schematic side view showing another embodiment of the present invention.

[Explanation of symbols]

 1 Sheet-shaped substrate 2 Resin liquid supply device 3a, 3b Resin liquid 4 Coating device 5 Heating device 6 Heating / drying device 7 Resin adhesion amount adjusting device 8a, 8b Guide roll 7a, 7b Pressing roll 7c Rotating roll 7d Resin liquid tank

Claims (4)

[Claims] 1. A method for producing a prepreg by impregnating a sheet-like base material made of a fibrous material with a resin liquid and then heating and drying the resin liquid, wherein the resin liquid is applied to one side of the sheet-like base material. Characterized by having a step of heating from the side opposite to the surface coated with the resin liquid at a temperature lower than the boiling point of the solvent used for the resin liquid, and then heating and drying the resin-impregnated sheet-shaped substrate Manufacturing method of prepreg. 2. A method for producing a prepreg by impregnating a sheet-like base material made of a fibrous material with a resin liquid and then heating and drying the resin liquid, wherein the resin liquid is applied to one side of the sheet-like base material. Step, heating the resin liquid at a temperature lower than the boiling point of the solvent used for the resin liquid from the opposite surface side, then applying the resin liquid to the opposite surface of the resin liquid applied surface, A method for producing a prepreg, which further comprises a step of heating and drying the resin-impregnated sheet-shaped substrate. 3. An apparatus for applying a resin liquid to one surface side of a sheet-shaped base material made of a fibrous material, and a sheet-shaped base material having the resin liquid applied to one surface side opposite to the surface coated with the resin liquid. An apparatus for manufacturing a prepreg, comprising: a heating device for further heating and a heating / drying device through which a resin-impregnated sheet-shaped substrate passes. 4. An apparatus for applying a resin liquid to one side of a sheet-shaped base material made of a fibrous material, and a sheet-shaped base material having a resin liquid applied to one surface side opposite to the surface coated with the resin liquid. A heating device for further heating, and a resin adhesion amount adjusting device for adhering the resin liquid to the surface opposite to the surface first coated with the resin liquid in order to adjust the resin adhesion amount of the sheet-shaped substrate impregnated with the resin liquid. And a heating / drying device through which the resin-impregnated sheet-shaped substrate passes, the prepreg manufacturing device.