JP4990073B2 - Manufacturing method of long sheet of fiber reinforced plastic - Google Patents

Description

  The present invention relates to a method for producing a continuous fiber-reinforced plastic long sheet. According to the method for producing a long fiber-reinforced plastic sheet of the present invention, it is possible to produce a long fiber-reinforced plastic sheet having a high thickness accuracy and a smooth surface even when the width is widened.

The continuous fiber-reinforced plastic long sheet is used as an intermediate material for a porous electrode substrate for a polymer electrolyte fuel cell, for example, obtained by binding carbon fiber paper with a carbonized resin.
Conventionally, batch-type production methods have been the mainstream, but by continuously performing hot pressing and firing, materials such as porous electrode base materials for polymer electrolyte fuel cells that have high productivity and low cost Can be molded.

  As a continuous fiber-reinforced plastic long sheet manufacturing method, a sheet containing reinforcing fibers and a thermosetting resin is sandwiched between a pair of belts and heated while being continuously drawn into a heating device and a die having a slit. The method of molding is introduced. (Patent document 1) Since the heat press time is long, there exists the characteristic that the fiber reinforced plastic long sheet | seat with high thickness accuracy is obtained.

  When the heating press time is long, the gas generated with the curing of the thermosetting resin is confined inside the sheet. For this reason, the fiber-reinforced plastic sheet being cured is deformed by the gas, and wrinkles and poor appearance are likely to occur. This problem becomes more noticeable especially when the sheet width is widened. In addition, since the belt is not preheated before being drawn into the die, there is a sudden heat change at the entrance of the die, so the belt is easily deformed. There were problems such as getting worse.

JP 2006-264329 A

  An object of the present invention is to provide a method for producing a long fiber-reinforced plastic sheet having a high thickness accuracy and a smooth surface even when the width is widened.

The present invention is as follows.
(1) A sheet containing carbon fiber and a phenolic resin composition is heated while being continuously drawn into a slit of a die in a state where both surfaces of the sheet are sandwiched between a pair of belts, thereby curing the phenolic resin composition. A method for producing a long sheet of fiber reinforced plastic, wherein the die comprises a pair of metal blocks embedded with a heating device and a spacer provided with a slit between the pair of metal blocks. The manufacturing method of the fiber reinforced plastic long sheet | seat which has this. (2) The method of (1), in which both surfaces of the sheet are sandwiched between a pair of belts and are preheated by a preheating device before being continuously drawn into the slit of the die.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the fiber reinforced plastic long sheet | seat with a smooth surface is provided even if it is high in thickness accuracy and wide.

Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.
FIG. 2 is a schematic view of an apparatus for explaining one embodiment of a process for producing a fiber-reinforced plastic long sheet of the present invention. FIG. 1 is a process for producing a fiber-reinforced plastic long sheet 1 according to an embodiment. It is a schematic longitudinal cross-sectional view for demonstrating one form, and is the elements on larger scale of FIG.

The method for producing the long fiber-reinforced plastic sheet 1 includes a heating device and a sheet 2 containing a carbon fiber and a phenolic resin composition in FIG. 1 in a state where both surfaces of the sheet 2 are sandwiched between a pair of belts 3. The phenol resin is cured by heating while continuously drawing into the die 4 having the slit 6.
Carbon fiber has high electrical conductivity and mechanical strength. In order to obtain a porous carbon long sheet as a material for a gas diffuser of a polymer electrolyte fuel cell, carbon short fibers are more preferable. The fiber length of the short carbon fiber is preferably 3 to 20 mm, and more preferably 5 to 15 mm. By setting the fiber length of the short carbon fiber within the above range, when the carbon short fiber is dispersed to make a paper to obtain a carbon fiber sheet, the dispersibility of the short carbon fiber can be improved and the variation in basis weight can be suppressed. .
The phenol resin composition has a high carbonization yield when heated in an inert atmosphere.

  The sheet 2 containing a carbon fiber and a phenol resin composition is obtained, for example, by impregnating a phenol resin composition into carbon fiber paper or carbon fiber felt made from short carbon fibers.

  The amount of the phenol resin composition is preferably 10 to 400 parts by mass, more preferably 30 to 300 parts by mass, and particularly preferably 50 to 200 parts by mass with respect to 100 parts by mass of the carbon fiber. Within this range, the carbon fiber binding force of the phenol resin composition is sufficient, and the variation in the thickness of the fiber-reinforced plastic long sheet 1 is small, which is preferable. In addition, the squeezed resin can be prevented from flowing out of the apparatus.

In the present invention, the die includes a pair of metal blocks in which a heating device is embedded and a spacer 12 that provides a slit 6 between the pair of metal blocks. By providing the spacer 12, a long fiber-reinforced plastic sheet with high thickness accuracy can be obtained.
As shown in FIGS. 3 and 4, the slit 6 of the die 4 is preferably provided by a spacer 12 sandwiched between a pair of metal blocks 11. Since the clearance of the die 4 can be adjusted by the spacer 12, it is not necessary to prepare the die 4 for every thickness required for the long fiber-reinforced plastic sheet 1. Further, since the die 4 can be assembled and disassembled, a pair of endless belts 7 can be used.

  Since the sheet 2 containing the carbon fiber and the phenol resin composition does not adhere to the die 4 due to the curing of the phenol resin composition, the width of the pair of belts 3 is preferably larger than the width of the sheet 2. That is, it is preferable that the entire surface of the sheet 2 is continuously drawn into the die 4 while being always covered with the pair of belts 3.

The first aspect will be described.
The spacer 12 has a gas vent hole. When the spacer 12 does not have a gas vent hole, a large amount of compressed gas is stored in the pressure press system. In particular, when the width and length to be pressurized become long, the sheet is deformed by the pressure in the system, causing an appearance defect.
In addition, if a strong belt that is difficult to be deformed so as not to cause an appearance defect is used, a large load is applied to the extraction. If the spacer 12 has a vent hole, the generated gas can be released out of the system, so that it can be applied to a case where the sheet width is wide or the sheet is pressed for a long time.
The shape of the gas vent hole is not particularly limited. For example, a shape in which a hole penetrating from the side of the sheet to the outside of the apparatus is opened as shown in FIG. 4 or FIG.

  Furthermore, it is preferable to install an exhaust fan or the like outside the gas vent hole to increase the discharge capability of the generated gas, since the appearance defect is less likely to occur.

The second aspect will be described.
In a state where both surfaces of the sheet 2 containing the carbon fiber and the phenol resin composition are sandwiched between a pair of belts, the sheet 2 is preheated with a preheating device before being continuously drawn into a die having a heating device and a slit 6. When the sheet 2 containing the carbon fiber and the phenol resin composition is drawn directly into the die without being heated by the preheating device, the belt expands or warps due to the temperature difference before and after entering the die.
When the sheet 2 containing the carbon fiber and the phenol resin composition is drawn into the die in a state where the belt is deformed, the pressure applied to the sheet in the width direction is different from the manner in which heat is applied, thereby causing pressure unevenness.
By heating with the preheating device, the deformation of the belt becomes gradual, so that thickness unevenness in the width direction of the sheet can be prevented.

The preheating device is not particularly limited, and examples thereof include a hot air generator and a heating roll. From the viewpoint that heating can be performed without bringing a roll into contact with the belt, a hot air generator is preferable.
The temperature difference before and after entering the belt die is preferably 100 ° C. or less, more preferably 70 ° C. The temperature of the belt in the preheating device is preferably 100 ° C. or less per meter, more preferably 70 ° C. or less per meter. As the temperature difference before and after entering the belt die and the temperature rise of the belt in the preheating device are both gentler, the distortion of the belt becomes smaller.
When molding with a die, the closer to the outside (edge) of the belt, the more likely it is affected by outside air, and the higher the temperature during pressing is. The thickness accuracy can be increased by changing the preheating temperature in the width direction, for example, by increasing the amount of hot air or by increasing the temperature of the outer preheating temperature in advance.

Hereinafter, the present invention will be described more specifically with reference to examples.
Embodiments of Examples and Comparative Examples are shown in Table 1.
The standard deviation of the thickness in the longitudinal direction of the long fiber-reinforced plastic sheet is calculated by measuring thickness data of 100 points or more at 5 cm intervals in the longitudinal direction of the long sheet. The standard deviation of the thickness in the width direction is calculated by measuring thickness data of 30 or more points at 1 cm intervals in the width direction of the long sheet. The thickness data is measured by applying a surface pressure of 0.15 MPa in the thickness direction of the long fiber-reinforced plastic sheet using a micrometer. The cross section of the micrometer probe is a circle having a diameter of 5 mm.

[Example 1]
A fiber bundle of polyacrylonitrile (PAN) -based carbon fibers having an average fiber diameter of 7 μm was cut to obtain short fibers having an average fiber length of 6 mm. Next, with respect to 100 parts by mass of the short fiber bundle, the short fibers of polyvinyl alcohol (PVA) as a binder are uniformly dispersed so as to be 20 parts by mass when sufficiently dispersed, and water is continuously used as a papermaking medium. Papermaking and drying were performed to obtain a long carbon fiber paper having a carbon fiber basis weight of about 32 g / m ² and wound into a roll.
The carbon fiber paper is continuously coated with a 25% by weight methanol solution of a phenol resin and dried at a temperature of 90 ° C. for 3 minutes to obtain a sheet 2 containing the carbon fiber and the phenol resin composition, which is wound into a roll. I took it.

  A sheet 2 containing carbon fiber and a phenol resin composition is trimmed to a length of 100 m and a width of 35 cm and sandwiched between a pair of stainless steel belts coated with fluorine by PTFE on both surfaces as a pair of belts 2. A long sheet of fiber reinforced plastic having a length of 100 m and a width of 35 cm by heating while continuously pulling into a die 4 having a slit 6 heated to a temperature of 0 ° C. at a speed of 0.6 m 2 / min and curing the phenol resin. 1 was obtained. A pair of stainless steel endless belts 7 having both surfaces coated with fluorine by PTFE as a pair of belts 3 is used as the die 4 having the slit 6 with a stainless steel metal block 11 sandwiching a PTFE spacer 12. Was used.

  The endless belt 7 used has a thickness of 200 μm, a width of 40 cm 2 and a length of 10 m, and the fluororesin layer coated on the stainless steel belt is 20 μm. The width of the slit 6 provided in the die 4 is 44 cm 2, the width of the die 4 is 50 cm 2, and the length is 18 cm 2.

A roller chain with an attachment was attached to the endless belt 7 as a power transmission portion 8 over the entire circumference at both ends of the surface in contact with the die 4 (the inner surface of the endless belt 7). Further, power was transmitted from a sprocket with a diameter of 30 cm as the drive unit 9 via a roller chain. The metal block 11 has a length of 18 cm, a width of 50 cm, and a height of 5 cm. The long side of the surface on the slit 6 side is R-processed, and the surface on the slit 6 side is mirror-finished. What provided the groove | channel for the roller chain attached to 7 to pass was used. The PTFE spacer 12 was 18 cm long, 3 cm wide, and 620 μm thick. The spacer 12 had two vent holes as shown in FIG. The size of the vent hole was 5 cm in length, 3 cm in width, and 400 μm in height (in the thickness direction).
The evaluation results of the obtained fiber reinforced plastic long sheet 1 are shown in Table 2. Not only in the longitudinal direction but also in the width direction, the thickness accuracy was high and there was no appearance defect.

[Example 2]
As shown in FIG. 2-2, the preheating device 5 was installed in front of the dice, heated by the preheating device 5, and then drawn into the die. The preheating device 5 applies hot air to the belt. The size of the preheating device 5 was 1.2 m in length and 50 cm in width, and the temperature at the inlet of the preheating device was 30 ° C., whereas the temperature at the outlet was 150 ° C. In addition, the fiber-reinforced plastic long sheet 1 was obtained by the same method as Example 1 except the temperature when heat-molding with a die was 210 degreeC. The evaluation results are shown in Table 2. The thickness accuracy in the longitudinal direction and the width direction was higher than that of Example 1, and the appearance was also satisfactory.

[Comparative Example 1]
A long fiber-reinforced plastic sheet 1 was obtained in the same manner as in Example 1 except that a spacer having no vent hole (the spacer 10 shown in FIGS. 4 and 5) was used. The evaluation results are shown in Table 2. Although the thickness accuracy in the longitudinal direction is good, the unevenness in the width direction is large. In addition, there were 10 dents in the 100 m sheet formed by gas foaming.

[Comparative Example 2]
As a pair of belts 3, a fluorine coating glass cross Chuko flow (registered trademark) belt BGF-500-6 (thickness 125 μm) manufactured by Chuko Kasei Kogyo Co., Ltd. was used, and the clearance of the slit 6 provided in the die 4 was set to 390 μm. Except for the above, a fiber-reinforced plastic long sheet 1 was obtained in the same manner as in Comparative Example 1. The evaluation results of the obtained fiber reinforced plastic long sheet 1 are shown in Table 2.
Although the thickness accuracy in the longitudinal direction is good, the unevenness in the width direction is large. There were 15 indentations created by gas foaming out of a 100 m sheet. The belt also had a large slack.

It is a schematic longitudinal cross-sectional view for demonstrating one form of the manufacturing process of the prior art and the fiber reinforced plastic long sheet | seat of this invention. It is the schematic longitudinal cross-sectional view which shows one form of the manufacturing process of the prior art and the fiber reinforced plastic long sheet | seat of this invention, and the schematic of the temperature and pressure history which a fiber reinforced plastic long sheet receives. It is a schematic sectional drawing for demonstrating other forms of the manufacturing process of the prior art and the fiber reinforced plastic long sheet | seat of this invention. FIG. 4 is a partial cross-sectional view of the A-A ′ plane of FIG. 3. It is a schematic sectional drawing for demonstrating one form of the spacer used by this invention. (Plan view seen in the direction of the arrows (b) and (b) in FIG. 4)

Explanation of symbols

1: Fiber reinforced plastic long sheet 2: (including carbon fiber and phenolic resin composition) Sheet 3: A pair of belts 4: Dies 5: Preheating device 6: Slit 7: A pair of endless belts 8: Tension transmission part 9 : Drive unit 10: Conventional spacer 11: Metal block 12: Example of spacer of the present invention 13: Example of spacer of the present invention

Claims (2)

A sheet containing carbon fiber and a phenolic resin composition is heated in a state where both surfaces of the sheet are sandwiched between a pair of belts while being continuously drawn into a slit of a die, and fiber reinforced to cure the phenolic resin composition. A method for producing a plastic long sheet, wherein a die includes a pair of metal blocks in which a heating device is embedded and a spacer provided with a slit between the pair of metal blocks, and the spacer further has a gas vent hole. A method for producing a long sheet of fiber-reinforced plastic.   The method according to claim 1, wherein the two surfaces of the sheet are sandwiched between a pair of belts and are preheated by a preheating device before being continuously drawn into the slit of the die.

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