JPH09157415A - Production of prepreg and apparatus for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a prepreg containing an extremely small amount of bubbles in a sheetlike substrate comprising a fibrous material even when using a resin liquid at a high concentration. SOLUTION: This method for producing a prepreg comprises coating one surface side of a sheetlike substrate 1 with a resin liquid (3a), then heating the resultant sheetlike substrate 1 from the side of the surface coated with the resin liquid (3a) at a lower temperature than the boiling point of a solvent used in the resin liquid (3a) and subsequently drying the substrate by heating thereof at a higher temperature than the boiling point of the solvent when impregnating the sheetlike substrate 1 comprising a fibrous material with the resin liquid (3a), then drying the resultant substrate and thereby producing the prepreg. Furthermore, the apparatus adopts the method for producing the 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 normal that the air bubbles in the fibrous material 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) to impregnate the resin liquid into the fiber material of the sheet-shaped base material. However, it is impractical because the production efficiency is extremely poor and the equipment is lengthened. 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 According to the present invention, in the conventional prepreg manufacturing method, when a sheet-shaped base material made of a fiber material is impregnated with a high-concentration resin liquid, a large amount of air bubbles remain in the fiber material. It was made as a result of various investigations in order to solve the problem, and the purpose is to improve the impregnation of the resin liquid into the fiber material of the sheet-shaped base material and to perform it uniformly, thereby making it possible to obtain a high-concentration resin liquid. It is an object of the present invention to provide a resin liquid impregnation method for obtaining a prepreg having extremely few air bubbles in a sheet-shaped substrate made of a fibrous material even when the above method is used, and an apparatus for optimally implementing the method.

[0005]

Means for Solving the Problems In the present invention, when a sheet-like base material made of a fiber material is impregnated with a resin liquid and then dried, a prepreg is produced.
After applying the resin liquid on one side of the sheet-shaped substrate, first heat from the opposite side of 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 from the boiling point of the solvent. The present invention relates to a method for producing a prepreg, which comprises heating and drying at a high temperature. That is, the prepreg manufacturing method of the present invention is a coating step of applying a resin liquid on one side of a sheet-shaped base material made of a fibrous material, by heating the sheet-shaped base material that has undergone the step, to reduce the viscosity of the resin liquid. The heating step of impregnating the inside of the fibrous material of the sheet-shaped substrate and the heating and drying step of vaporizing the solvent contained in the resin liquid and making the resin semi-cured are indispensable steps.

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 / drying step, a deposition amount adjusting step for continuously adjusting the resin deposition amount is added, and then a heating drying step for heating and drying the applied resin liquid and the resin liquid for adjusting the deposition amount is provided. It is preferable. In the resin adhesion amount adjustment process, even if only one other surface different from the surface applied to impregnate the resin liquid at the beginning,
Alternatively, it may be selected from both sides, and it can be selected depending on the type and properties of the sheet-shaped base material and the resin liquid to be impregnated and the required quality of the prepreg to be obtained, but when considering the cost of the device and the balance of the amount of adhesion on both sides. The former is preferable. It should be noted that the resin adhesion amount adjusting step does not have to be continuous with the preceding step, and may be carried out after a certain time after winding once, but a winding device and man-hours are required. Therefore, it is not preferable.

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. Of the sheet-shaped substrate to be used and the resin liquid to be impregnated, which is configured 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, it is a prepreg manufacturing apparatus in which a resin amount adjusting device is further installed in front of the 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 higher impregnation property as when a resin liquid having a solid content of 55% or more is used and which has the same or better impregnation as when a resin liquid having a conventional low concentration is used. Is.

The steps of the present invention will be sequentially described below. (Resin liquid coating step) Instead of storing the high-concentration resin liquid in the impregnation tank, by supplying a necessary amount to the sheet-shaped substrate and applying from one side, the volatilization of the solvent from the resin liquid is suppressed,
High-concentration resin liquid can be maintained at a constant concentration and viscosity.

(Heating step) This is a step of heating the sheet-shaped base material coated with the high-concentration resin liquid to reduce the viscosity of the resin liquid and easily replace the air in the fiber material. . 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. Furthermore, when heating from the surface coated with the resin liquid, the temperature of the resin liquid rises before that of the sheet-shaped substrate, so even if the resin liquid has a low viscosity, the sheet-shaped substrate has a lower temperature. This is not preferable because it lowers the temperature, hinders lowering of the viscosity, and lowers the impregnating property. Therefore, heating the sheet-shaped base material from the side opposite to the surface coated with the resin liquid improves the impregnation property. It may be heated from both sides, but it is clear that the effect is less than that of 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 and the resin is semi-cured in the subsequent heat drying step. High energy is required for this purpose, which is not preferable. For solvents with a boiling point of 70 ° C or less, after being applied to a sheet-shaped substrate, the solvent is gradually vaporized even at room temperature, and the heating temperature is 5 to avoid bumping.
Although it must be 0% or less, when the heating temperature is low, the viscosity of the resin liquid is not lowered so much and the impregnation property into the fiber material is insufficient, which is not preferable. Therefore, the boiling point is preferably 70
C. to 160.degree. C. are used alone or as a mixture of two or more.

(Heating and drying step) By heating and drying at a temperature higher than the boiling point of the solvent used in the resin liquid, the solvent in the resin liquid is vaporized and a prepreg in which the resin is semi-cured is obtained. You can The heating and drying method may be a conventionally used method and is not particularly limited.

[0014]

EXAMPLES Examples 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. Transfer to. The following epoxy resin liquid 3a is applied to the upper surface side of the coater using a resin liquid supply device 2 such as a nozzle at an amount of about 124 g per minute. The gap between the support 4b and the coater 4a such as a coater roll or a doctor knife is adjusted to 10.2 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 both surfaces are heated and dried by the heating and drying device 6. Was 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 about 61.5% (boiling point of dimethylformamide 153 ° C)

Example 2 In this example, 21.0 g
/ M ² of glass cloth is shown. The epoxy resin liquid 3a shown in the above table was transferred to the coating device 4 at a speed of 3 m / min in the same manner as in Example 1, and the epoxy resin liquid 3a shown in the above table was applied at a rate of about 214 per minute on the upper surface side of the glass cloth.
It is applied in the amount of g. 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 at an amount of about 38 g per minute. . Epoxy resin liquid 3 in resin liquid tank 7d
b may be the same as or different from the epoxy resin liquid 3a to be applied first, 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.

As a result of observing the prepregs of Examples 1 and 2 under a microscope of 50 times for presence or absence of air bubbles in the prepreg, the number of voids was very small in both cases, and epoxy resin solutions of the same composition were used. The number of voids was significantly smaller than that of the prepreg obtained by the usual impregnation method.

[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 lowering the viscosity of the resin liquid while suppressing vaporization of the solvent in the resin liquid, and it is extremely It is possible to obtain a 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 the 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

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Claims (4)

[Claims] 1. When a prepreg is manufactured by impregnating a sheet-shaped base material made of a fibrous material with a resin liquid and then drying the prepreg, a resin liquid is applied to one surface side of the sheet-shaped base material, First, a method for producing a prepreg, which comprises heating at a temperature lower than the boiling point of the solvent used for the resin liquid from the side opposite to the surface coated with the resin liquid, and then heating and drying at a temperature higher than the boiling point of the solvent. 2. When a prepreg is manufactured by impregnating a sheet-like base material made of a fibrous material with a resin liquid and then drying the prepreg, a resin liquid is applied to one side of the sheet-like base material, First, heat at a temperature lower than the boiling point of the solvent used for the resin liquid from the opposite side of the surface coated with the resin liquid, and then apply the resin liquid to the opposite surface of the surface coated with the resin liquid, and further to the resin liquid. A method for producing a prepreg, which comprises heating and drying at a temperature higher than the boiling point of the solvent used. 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 producing a prepreg, comprising: a heating device for further heating; and a heating / drying device through which a sheet-shaped substrate coated with a resin liquid 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 opposite surface of 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 the resin An apparatus for producing a prepreg, comprising: a heating / drying apparatus through which a sheet-shaped substrate coated with the liquid passes.