JP3150591B2 - Prepreg manufacturing method and manufacturing apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, in the case of impregnating a sheet-like substrate made of a fiber material with a resin liquid, the sheet-like substrate is immersed in the resin liquid and passed through the resin liquid to impregnate the sheet-like substrate with the resin liquid. The operation is performed, but at this time, the air bubbles in the fibrous material of the sheet-like base material do not escape, and it is usual that the air bubbles remain in the prepreg, so that a laminate obtained by laminating this prepreg is used. Voids often occur. It is necessary to carry out lamination molding under a high pressure in order to prevent voids from being generated and the electrical characteristics and appearance from being impaired.
However, laminates such as electric insulating boards and decorative boards obtained by lamination molding under such a high pressure have problems that the dimensional stability is deteriorated and that the laminates are warped or twisted.

In order to obtain a laminate having excellent dimensional stability and a small warpage or twist, it is necessary to carry out lamination molding at a low pressure. It is necessary to use a prepreg with almost no residual air bubbles. As a method of obtaining a prepreg having almost no residual air bubbles, there is a method of dipping a sheet-like substrate in a resin solution for a long time (about 10 minutes or more) to impregnate the resin solution into the fiber material of the sheet-like substrate. However, it is impractical because the production efficiency is extremely poor and the equipment is long. In particular, it is almost impossible in the case of a high-concentration resin solution. Also, 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 sheet-like substrate with the resin liquid by the vibration of the substrate and the resin liquid. Although it has been proposed, the temperature of the resin liquid becomes high due to the ultrasonic vibration and the solvent in the resin liquid evaporates, so that the viscosity of the resin liquid sharply increases and impregnation property is reduced. In order to prevent this, it is necessary to constantly add a solvent to keep the resin liquid at a constant concentration. However, there is a problem that a viscosity adjusting device is required, and further, the cost increases due to the addition of the solvent.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a conventional prepreg manufacturing method in which a high-concentration resin solution impregnated into a sheet-like base material made of a fibrous material results in a prepreg having a large amount of air bubbles remaining in the fibrous material. In order to solve the problems, various studies have been made. The purpose is to improve the impregnation of the fibrous material of the sheet-like base material with the resin liquid, and to perform the treatment uniformly, so that the high-concentration resin liquid can be obtained. An object of the present invention is to provide a resin liquid impregnating method for obtaining a prepreg having extremely few bubbles in a sheet-like base material made of a fibrous material even when using a resin material, and an apparatus for optimally performing the method.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a method for producing a prepreg by impregnating a sheet-like substrate made of a fibrous material with a resin liquid and then drying the resin liquid.
After applying the resin liquid on one side of the sheet-shaped substrate, first heating from the opposite side of the surface on which the resin liquid was applied 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, characterized by heating and drying at a high temperature. That is, the prepreg production method of the present invention is a coating step of applying a resin liquid on one side of a sheet-like base material made of a fibrous material, and by heating the sheet-like base material after the step, the viscosity of the resin liquid is reduced. A heating step of impregnating the inside of the fibrous material of the sheet-like base material and a heating and drying step of evaporating a solvent contained in the resin liquid and setting the resin in a semi-cured state are essential steps.

[0006] Further, depending on the type and properties of a sheet-like substrate made of a fibrous material and the resin liquid used for the same, the amount of the resin adhered to a predetermined amount can be reduced only by the step of applying to one side of the sheet-like substrate. May not be. In this case, after the heating and drying step, a coating amount adjustment step for continuously adjusting the resin adhesion amount is added, and then a heating and drying step of heating and drying the first applied resin liquid and the resin liquid for the adhesion amount adjustment is provided. Is preferred. In the resin adhesion amount adjustment step, even if only the other surface that is different from the surface that was first applied to impregnate the resin liquid,
Or from both sides, it can be selected according to the type and properties of the sheet-like base material and the resin liquid to be impregnated and the required quality of the prepreg to be obtained, but in consideration of the cost of the apparatus and the balance of the amount of adhesion on both sides. The former is preferred. Note that the resin adhesion amount adjustment step does not need to be continuous with the previous step, and may be carried out after winding once and after a while, but requires an apparatus and man-hours for winding. This is not preferred.

On the other hand, a prepreg manufacturing apparatus of the present invention for carrying out such a method is an apparatus for applying a resin liquid to a sheet-like base material made of a fibrous material from one side, and a sheet-like base material impregnated with a resin liquid. Temperature below the boiling point of the solvent used for
A device that heats from the side opposite to the side on which the resin liquid has been applied,
And configured to sequentially pass through a device for heating and drying the sheet-like substrate impregnated with the resin liquid, depending on the type of sheet-like substrate and the resin liquid to be impregnated, the properties, etc., further a resin amount adjusting device, This is a prepreg manufacturing device installed before a drying device.

Examples of the sheet-like substrate made of a fiber material used in the present invention include glass cloth substrates such as glass cloth, glass non-woven cloth, and glass paper, as well as woven cloth made of paper and synthetic fibers, non-woven cloth, and metal. Examples thereof include woven fabrics and mats made of fibers and carbon fibers, and these base materials may be used alone or in combination. These sheet-like substrates are impregnated with a resin liquid and dried to produce a prepreg. In general, epoxy resins, polyimide resins, and modified resins thereof are preferably used as the resin liquid used in the present invention, but other resins such as thermoplastic resins and natural resins are also used. It is not limited to them. In addition, a filler, a colorant, and a reinforcing material can be compounded, and aluminum hydroxide, silica, talc, calcium carbonate, and the like can be appropriately compounded as needed as long as the object of the present invention is not adversely affected.

The viscosity of the resin liquid thus obtained is adjusted by mixing a solvent so as to easily impregnate a sheet-like substrate made of a fiber material. In general, the solid content is adjusted to about 50%, stored in an impregnation tank, and the sheet-like base material is passed through the resin liquid to replace the air in the fiber material with the resin liquid, thereby performing impregnation. ing. When the solid content exceeds 55%, the viscosity of the resin liquid increases, and the impregnating property of the resin liquid into the fiber material decreases,
Substitution with air in the fibrous material is difficult, and the prepreg is dried without sufficiently removing air bubbles, and a prepreg with many air bubbles remaining is obtained. Normally, even if the solid content increases, the resin liquid is heated to reduce the viscosity.However, if the resin liquid contains a low melting point solvent, the solvent is gradually vaporized and impregnated. It becomes difficult to control the application conditions in the tank. Therefore, a method of using a high boiling point solvent and heating at a temperature lower than the boiling point has been adopted.However, when the temperature is raised to a temperature higher than necessary, the solvent is easily evaporated. You. Even under these conditions, the solvent evaporates gradually, increasing the concentration,
In order to increase the viscosity, a device for controlling the concentration and viscosity of the resin liquid is provided, and a solvent is appropriately added. This is contrary to the purpose of reducing raw material costs by using a high-concentration resin solution. The present invention provides a prepreg having impregnating properties equal to or higher than that of a conventional low-concentration resin liquid even when a resin liquid having a solid content of 55% or more is used, and having few voids even after a drying step. It is.

Hereinafter, the steps of the present invention will be sequentially described. (Resin liquid application step) Rather than storing the high-concentration resin liquid in the impregnation tank, the required amount is supplied to the sheet-like base material and applied from one side to suppress volatilization of the solvent from the resin liquid,
High-concentration resin liquid can be maintained at a constant concentration and viscosity.

(Heating Step) This step is a step of heating the sheet-like base material coated with the high-concentration resin liquid to lower the viscosity of the resin liquid and easily replace the air with 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 bumping of the solvent, the impregnation of the resin liquid is extremely reduced, and a large amount of Foaming will occur. In order to solve this problem, it is necessary to heat the resin liquid at a temperature lower than the boiling point of the solvent used. Furthermore, when heating from the surface to which the resin liquid is applied, the temperature of the resin liquid rises before the sheet-like base material. It is not preferable because the temperature is lowered to prevent lowering the viscosity and impregnating property is lowered. For this reason, heating from the side opposite to the surface of the sheet-shaped substrate to which the resin liquid has been applied will further improve the impregnation. Although heating may be performed from both sides, it is clear that the effect is smaller than the above-described method in which heating is performed from the side opposite to the side on which the resin liquid is applied.

The solvent used in the resin liquid is preferably one having a high boiling point. If the solvent exceeds 160 ° C., the solvent contained in the resin liquid is vaporized and the resin is semi-cured in the subsequent heating and drying step. This is not preferable because high energy is required to perform this. Solvents having a boiling point of 70 ° C. or less, after being applied to a sheet-like substrate, are gradually vaporized even at room temperature, and heated to a temperature of 5 ° C. to prevent bumping.
However, if the heating temperature is low, the viscosity of the resin liquid is not easily reduced, and the impregnation property of the fiber material is insufficient. Therefore, preferably the boiling point is 70
C. to 160.degree. C., or a mixture of two or more.

(Heat 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 the prepreg in which the resin is in a semi-cured state is obtained. I can do it. The heating and drying method may be a method conventionally used, and is not particularly limited.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 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 8a, and was coated with a support 4b and a coater roll or a coater 4a such as a doctor knife. Transfer to The following epoxy resin liquid 3a is applied on the upper surface side of the coater at a rate of about 124 g per minute using the resin liquid supply device 2 such as a nozzle. 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 side is immediately transferred to a heating device 5, heated from the lower surface side by hot air at an ambient temperature of 120 ° C. for about 1 minute, and then heated and dried by a heating and drying device 6 on both sides. Was dried by heating at an atmosphere 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 Hardening agent Dicyandiamide 3.5 Accelerator Imidazole 0.15 Resin liquid solids content about 61.5% (boiling point of dimethylformamide) : 153 ° C)

<< Embodiment 2 >> In this embodiment, 21.0 g
/ M ² glass cloth. The epoxy resin liquid 3a shown in the above table was transferred to the coating device 4 at a speed of 3 m / min.
g. At this time, the gap between the support 4b and the coater 4a such as a coater roll or a doctor knife is adjusted to 0.32 mm in advance.

Glass cloth 1 coated with a resin liquid on one side
Is immediately transferred to the heating device 5 and the atmosphere temperature 1
After heating with hot air of 20 ° C. for about 1 minute and 30 seconds, the epoxy resin liquid 3b is applied on the lower surface side at an amount of about 38 g per minute by the resin adhesion amount adjusting device 7 composed of the holding rolls 7a and 7b and the rotating roll 7c. . Epoxy resin liquid 3 in resin liquid tank 7d
b may be the same as the epoxy resin liquid 3a to be applied first or may be different, and is appropriately selected as needed. After that, both sides are heated 180 by the heating and drying device 6.
About 22.4% of resin after drying at ambient temperature of about 2 minutes
Prepreg was obtained.

The prepregs of Examples 1 and 2 were observed under a microscope at a magnification of 50 times to check for the presence of air bubbles in the prepreg. As a result, the number of voids was very small. The number of voids was much smaller than that of the prepreg obtained by the conventional impregnation method.

[0020]

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

[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]

 REFERENCE SIGNS LIST 1 sheet-like base material 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 holding roll 7c rotating roll 7d resin liquid tank

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ identification code FI B29K 105: 08 309: 08 (58) Investigated field (Int.Cl. ⁷ , DB name) C08J 5/24 CFC B29B 13/06 B29B 15/10 B32B 27/04

Claims (4)

(57) [Claims] 1. A method for manufacturing a prepreg by impregnating a sheet-like substrate made of a fibrous material with a resin liquid and then drying the resin liquid, applying a resin liquid to one surface of the sheet-like substrate, A method for producing a prepreg, comprising: first heating at a temperature lower than the boiling point of the solvent used for the resin liquid from the side opposite to the surface on which the resin liquid has been applied, and then drying by heating at a temperature higher than the boiling point of the solvent. 2. A method for impregnating a sheet-like substrate made of a fibrous material with a resin liquid and then drying the impregnated resin to produce a prepreg, after applying a resin liquid to one side of the sheet-like substrate, First, heat at a temperature lower than the boiling point of the solvent used for the resin liquid from the side opposite to the side where the resin liquid was applied, and then apply the resin liquid to the opposite side to the side where the resin liquid was applied, and further apply the resin liquid A method for producing a prepreg, comprising heating and drying at a temperature higher than the boiling point of the solvent used. 3. An apparatus for applying a resin liquid on one side of a sheet-like base material made of a fibrous material, and a temperature lower than a boiling point of a solvent used for the resin liquid on the sheet-like base material coated with the resin liquid on one side.
Manufacturing apparatus of the prepreg, characterized the heating device resin liquid is heated from the opposite side of the coated surface, that sheet-like base material resin liquid has been applied is equipped with a heating drying device that passes in degrees. 4. An apparatus for applying a resin liquid to one side of a sheet-like substrate made of a fibrous material, and a temperature lower than a boiling point of a solvent used for the resin used for the sheet-like substrate having the resin liquid applied to one side.
In order to adjust the amount of resin adhering to the sheet-like substrate impregnated with the resin liquid, a heating device that heats from the opposite side of the surface coated with the resin liquid at An apparatus for manufacturing a prepreg, comprising: a resin adhering amount adjusting device for adhering a resin liquid; and a heating / drying device through which a sheet-like base material coated with the resin liquid passes.