JPH09235395A - Impregnation of resin liquid and apparatus for impregnation resin liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a prepreg hardly containing voids. SOLUTION: This method for impregnating a resin liquid 3 is to continuously coat one surface side of a sheetlike substrate 1 comprising a fiber material with the resin liquid 3 and impregnate the sheetlike substrate 1 with the resin liquid 3. The sheetlike substrate 1 is heated at a lower temperature than the boiling point of a solvent contained in the resin liquid 3 applied to the sheetlike substrate 1 and one surface side of the sheetlike substrate 1 kept in the heated state is coated with the resin liquid 3 and further heated at a lower temperature than the boiling point of the solvent contained in the resin liquid 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin liquid impregnation method and an impregnation apparatus for continuously applying a resin liquid to one side of a sheet-shaped base material made of a fiber material and impregnating the sheet-shaped base material with the resin liquid. The present invention provides a resin liquid impregnation method and an impregnation apparatus suitable for producing a prepreg for an electrical insulating plate such as a printed wiring board for an industrial device or an electronic device, or a laminated plate such as a decorative plate. is there.

[0002]

2. Description of the Related Art Conventionally, when a sheet-like base material made of a fibrous material is impregnated with a resin liquid, an operation of immersing the sheet-like base material in the resin liquid and passing it through the resin liquid for impregnation is performed. Air bubbles between the fibers of the sheet-shaped substrate do not escape,
Since air bubbles usually remain in the prepreg, voids are often generated in the laminated plate obtained by laminating the prepreg.

The following method has been developed as a method for solving the problems of the conventional method. As shown in FIG. 2, a typical apparatus is one in which a resin liquid is continuously applied to one side of a sheet-shaped substrate made of a fibrous material to impregnate the sheet-shaped substrate with the resin liquid. That is, the resin liquid supply device 2 is provided on one side of the sheet-like base material 1 transferred using the coating device 4 including the support 4b and the coater roll or the coater 4a such as a doctor knife through the guide roll 6a.
Further, the resin liquid 3 is applied and impregnated. The sheet-shaped base material impregnated with the resin liquid is heated at a temperature lower than the boiling point of the solvent used for the resin liquid, and the amount of the resin attached is adjusted as it is or further, and then dried by heating at a high temperature. The impregnated resin is semi-cured to obtain a prepreg.

[0004]

However, according to such a prepreg manufacturing method, when the sheet-shaped substrate is thin, a good prepreg free of voids can be obtained.
When a high-concentration resin liquid (resin content 55% by weight or more) is impregnated into a sheet-shaped substrate having a normal thickness (180 to 200 μm) or more, a prepreg in which bubbles remain between the fibers of the substrate becomes a problem. The points still remain. The present invention has been made as a result of various studies in order to solve such a problem, and the purpose thereof is to make it possible to further sufficiently and uniformly impregnate a sheet-shaped substrate with a resin liquid, It is an object of the present invention to provide a resin liquid impregnation method capable of obtaining a prepreg having extremely few bubbles in a sheet-shaped base material even when a concentrated resin liquid is used, and an impregnation apparatus for optimally implementing the method.

That is, the inventors of the present invention have made earnest studies to shorten the equipment and improve the efficiency. As a result, it is more preferable to preheat the sheet-shaped substrate to which the resin liquid is applied, and more preferably It has been found that by heating the liquid as well, the time required for the resin liquid to permeate between the fibers of the sheet-shaped substrate can be shortened, and the device for the heating step after coating can be shortened. It is a thing.

[0006]

The resin liquid impregnation method of the present invention is an impregnation in which a resin liquid is continuously applied to one side of a sheet-like base material made of a fibrous material and the sheet-like base material is impregnated with the resin liquid. In the method, the sheet-shaped substrate is heated, and in that state, the resin liquid is applied to one side of the sheet-shaped substrate, and further heated at a temperature lower than the boiling point of the solvent used for the resin liquid. A method for impregnating a resin liquid, and a device for heating a sheet-shaped base material for carrying out such a method, a device for applying a resin liquid on one side of the sheet-shaped base material, and a device for applying the resin liquid through these devices. A resin impregnating device capable of lowering the viscosity of the resin liquid and sufficiently and uniformly impregnating the fibers of the sheet-shaped substrate by having a device for heating the sheet-shaped substrate impregnated with the resin liquid. It is a thing.

In the present invention, the sheet-shaped substrate is heated before the resin liquid is applied from one side of the sheet-shaped substrate, and when the resin liquid comes into contact with the sheet-shaped substrate, the resin liquid has a low viscosity. Turned into
The first feature is to promote impregnation between the fibers of the base material. Furthermore, by heating the resin liquid in advance,
Even if the resin liquid is supplied to the sheet-shaped substrate, the resin liquid can be kept at a low viscosity without lowering the temperature of the sheet-shaped substrate.

The resin liquid will be described. The resin is usually a thermosetting resin, and epoxy resins, polyimide resins, and modified resins thereof are preferably used, but other resins such as thermoplastic resins and natural resins are also used, and are not limited to these. . 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 if necessary within the range not deviating from the object of the present invention.

Although various solvents can be used, those having a higher boiling point than conventional ones are preferable. However, 160
Those having a temperature of more than 0 ° C. are not preferable because they require high energy in order to vaporize the solvent contained in the resin liquid and further to make the resin semi-cured in the subsequent heat drying step. 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, the boiling point is usually 70 to 160.
Solvents at a temperature of 100 ° C., preferably 100 to 160 ° C. are used singly or as a mixture of two or more kinds. Specific examples of preferable solvents include dimethylformamide (boiling point 153 ° C.),
Methyl isobutyl ketone (boiling point 116 ° C), xylene (boiling point 140 ° C), butyl acetate (boiling point 126 ° C), propylene glycol monomethyl ether (boiling point 120 ° C)
Etc.

In the present invention, the concentration of the resin liquid may be about 50%, which is the same as in the conventional method, but is preferably 55 to 70.
%. With such a high concentration, the amount of solvent can be reduced.

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. From the viewpoint of the effect of improving the impregnating property which is the object of the present invention, a woven fabric such as a glass cloth having poor impregnating property is preferably used.

Next, when the resin liquid is applied and impregnated on one side of the sheet-shaped substrate, particularly in the case of the high-concentration resin liquid, the viscosity is still high and the permeation between the fibers of the substrate is insufficient. By heating the sheet-shaped base material that has passed through, the viscosity of the resin liquid is reduced and the impregnation between the fibers is promoted. At this time, if the temperature is higher than the boiling point of the solvent used for the resin liquid, the concentration of the resin liquid will increase due to the rapid evaporation of the solvent, impregnation of the resin liquid will decrease, and defoaming will not be possible. A large amount of foaming will occur in the resin. In order to solve this problem, it is necessary to heat the sheet-shaped substrate coated with the resin liquid at a temperature lower than the boiling point of the solvent. 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.

The temperature at which the sheet-shaped substrate, or the sheet-shaped substrate and the resin liquid are preheated, is preferably kept at a temperature lower than the boiling point of the solvent used in the resin liquid for the same reason as above. The heating temperature is generally 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. The temperature is preferably 50 to 120 ° C, more preferably 60 to 80 ° C. Therefore, in the present invention, it is not preferable to use a solvent having a boiling point of about 70 to 80 ° C. as the solvent of the resin liquid because the viscosity of the resin liquid cannot be sufficiently lowered. If the heating temperature is high, the solvent of the resin liquid may evaporate more, and since it is a pre-stage process for heating the resin liquid after impregnating the sheet-shaped base material to increase the impregnation property, it is usually It is not necessary to exceed 120 ° C.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The steps of the present invention will be sequentially described below.

(Sheet-shaped base material heating step) The sheet-shaped base material made of a fibrous material is heated by a heating device while being continuously transferred, and is subjected to the next resin liquid coating step. This reduces the viscosity of the resin liquid when it is applied and impregnates it into the sheet-shaped base material, so that the equipment for the heating process of the sheet-shaped base material can be shortened compared to conventional equipment, and efficient prepreg Can be achieved.

(Resin Liquid Coating Step) High concentration resin liquid is not stored in the impregnation tank and the sheet-shaped substrate is immersed therein,
By supplying the required amount of the resin liquid to the sheet-shaped substrate and applying it from one side, it is possible to suppress the volatilization of the solvent from the resin liquid and to maintain the high-concentration resin liquid at a constant concentration and viscosity. As described above, it is preferable that the resin liquid is heated to have a low viscosity before being applied to the sheet-shaped substrate in order to improve the impregnation property.

(Resin-impregnated sheet-shaped substrate heating step) By heating the sheet-shaped substrate coated with the high-concentration resin liquid, the viscosity of the resin liquid is reduced and the air in the fiber material is replaced. This is an easy process. If this heating is performed from the side opposite to the surface of the sheet-shaped substrate on which the resin liquid is applied, the impregnation property will be further improved. If the temperature of the resin liquid rises before the sheet-shaped substrate when heated from the surface coated with the resin liquid, the temperature of the resin liquid is low because the temperature of the sheet-shaped substrate is lower even if the viscosity of the resin liquid decreases. Cannot be increased, which hinders lowering of viscosity and lowers impregnability, which is not preferable. 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.

(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 used for the resin liquid, and if necessary, the resin is semi-cured. It is possible to obtain a prepreg in a state. The heating and drying method may be a conventionally used method and is not particularly limited.

In order to carry out the above method, in the resin liquid impregnating apparatus of the present invention, the sheet-shaped substrate is heated by an electric heat in order to heat it to a temperature lower than the boiling point of the solvent of the resin liquid.
The resin solution is transferred in intimate contact with the surface of a heating device such as a plate or roll heated by steam or the like, and the resin liquid is continuously supplied and applied to one side of the sheet-shaped substrate from the resin supply device. A warming device such as an electric heater that utilizes radiant heat may be attached to the upper part of the heating device such as the plate or the roll in order to prevent heat radiation from the sheet-shaped substrate.

In the resin liquid impregnating method and the resin liquid impregnating apparatus of the present invention, the sheet-shaped base material is heated by adhering the sheet-shaped base material made of a fibrous material to the heating device so that the sheet-shaped base material is heated. Since the resin liquid becomes less viscous from the time of application and is impregnated into the sheet-shaped base material, the heating device for the resin liquid-impregnated sheet-shaped base material can be shortened compared to conventional equipment, and efficient production of prepreg is achieved. can do. in addition,
By heating the resin liquid to a temperature lower than the boiling point of the solvent, a low viscosity can be stably maintained, and impregnation into the sheet-shaped substrate can be promoted. It is preferable to use a rotating heat roll as a device for heating the sheet-shaped substrate because the sheet-shaped substrate can be kept at a constant temperature.

FIG. 1 shows a concrete example of the resin liquid impregnation method and the resin liquid impregnation apparatus of the present invention, but the present invention is not limited to such a concrete example. The glass cloth 1 is unwound, passed through guide rolls 6a and 6b, and transferred to a coating device including a heated heat roll 4c and a coater roll or a coater 4a such as a doctor knife. Resin liquid supply device 2 having resin liquid 3 on which a heating device 2a is installed
It is supplied on the glass cloth 1 and applied. It is advisable to provide a gap at a predetermined interval between the heat roll 4c and the coater roll or a coater 4a such as a doctor knife. The glass cloth coated with the resin liquid on one surface side is immediately sent to the heating device 5 and heated from the lower surface side to a temperature lower than the boiling point of the solvent of the resin liquid by hot air. After that, it is further heat-dried by a heat-drying device and preferably heat-dried at a temperature higher than the boiling point of the solvent to obtain a desired prepreg.

[0022]

[Example] 210 g / m ² of glass cloth 1 was unwound at a speed of 4 m / min, passed through guide rolls 6a and 6b and heated to 80 ° C.
The epoxy resin liquid 3 having the composition shown in the table below is transferred from the resin liquid supply device 2 which is transferred to a coating device composed of a heated heat roll 4c and a coater roll 4a and which is additionally provided with a heating device 2a on the upper portion.
Was applied and coated on a glass cloth at a rate of about 258 g / m ² . Heat roll 4c and coater roll 4 at this time
Adjust the gap between a and 0.3a in advance.
The glass cloth coated with the resin liquid on one surface side was immediately sent to the heating device 5 and heated from the lower surface side with hot air having an ambient temperature of 120 ° C. for 1 minute. 18 higher than the boiling point of the solvent
It was heated and dried at 0 ° C. to obtain a prepreg having a resin amount of about 43% by weight. Number of voids generated during this prepreg (5.
(Within an area of 2 mm ² ) is shown below by counting with a 50 × microscope.

<Resin Liquid Composition> Viscosity Resin Epoxy Resin 153.6 parts by weight Solvent Dimethylformamide 98.6 (boiling point 153 ° C.) Curing agent Dicyandiamide 3.5 Curing accelerator imidazole 0.15 Resin liquid solid content about 61.5 weight%

For comparison, the conventional device shown in FIG. 2 was used. That is, in the apparatus shown in the embodiment, the resin liquid supply device 2 without the heating device 2a is used, and the unheated support base 4b is used in place of the heat roll 4c in the coating device 4. Other than that, the same apparatus as in the above-mentioned example was used, and impregnation and drying were performed under the same conditions to obtain a resin amount of about 4
3% by weight of prepreg was obtained. The number of voids (in the area of 5.2 mm ² ) generated in this prepreg was counted by a 50 times microscope and is shown in the table below.

<Number of Voids in Prepreg> 0 in Example 20 to 30 in Comparative Example

[0026]

EFFECTS OF THE INVENTION According to the method and apparatus of the present invention, by heating the sheet-shaped substrate in advance, it is possible to prevent the solvent in the resin liquid from evaporating and to keep the resin liquid at a low viscosity. The resin liquid can be sufficiently and uniformly impregnated between the fibers of the material. Furthermore, since the impregnation between the fibers of the sheet-shaped base material starts immediately after the resin liquid is supplied to the sheet-shaped base material, the heating process equipment can be shortened compared to conventional equipment, and a prepreg with extremely few voids can be obtained. Obtainable.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a specific example of an impregnating apparatus of the present invention.

FIG. 2 is a schematic view showing a specific example of a conventional impregnation device.

[Explanation of symbols]

 1 Sheet-shaped substrate 2 Resin liquid supply device 2a Resin liquid heating device 3 Resin liquid 4 Coating device 4a Coater roll or doctor knife 4b Support 4c Heat roll 5 Heating device 6a, 6b Guide roll

Claims (5)

[Claims] 1. In an impregnation method in which a resin liquid is continuously applied to one side of a sheet-shaped substrate made of a fibrous material and the sheet-shaped substrate is impregnated with the resin liquid, the sheet-shaped substrate is heated.
A resin liquid impregnation method, characterized in that, in that state, a resin liquid is applied to one side of a sheet-shaped base material, and then heated at a temperature lower than the boiling point of a solvent contained in the resin liquid. 2. The resin liquid impregnation method according to claim 1, wherein a stationary or rotating heat roll or a fixed heat plate is used to heat the sheet-shaped substrate. 3. The resin liquid impregnation method according to claim 1, wherein the resin liquid in a preheated state is supplied and applied to the sheet-shaped substrate. 4. A device for heating a sheet-shaped substrate made of a fibrous material, a device for applying a resin liquid to one side of the sheet-shaped substrate, and a sheet to which the resin liquid is applied via these devices. And a device for heating the base material. 5. The resin liquid impregnating apparatus according to claim 4, further comprising a resin liquid supply device that supplies the resin liquid onto the sheet-shaped base material in a heated state.