JPH0460007B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a prepreg manufacturing method, and particularly to an improvement in resin impregnation treatment for reinforcing fibers.

[Prior art]

Unidirectional prepreg is made by superimposing resin-carrying sheets on both sides of reinforcing fibers in the form of strands arranged parallel to each other in a sheet shape, and reinforcing this superimposed body by pressing it with a pair of impregnated rolls. It is manufactured by expanding the fibers and transferring and impregnating the reinforcing fibers with resin.

When performing the above-mentioned resin impregnation, if you want to increase the transfer speed of the stacked body to increase productivity, or if you want to produce thick prepreg,
Resin impregnation of reinforcing fibers becomes uneven,
If the reinforcing fibers are not sufficiently expanded, the surface of the prepreg may lack smoothness. Also,
To solve this problem, if the linear pressure of the impregnating roll is too high, the resin will ooze out from the sheet edge and stain the impregnating roll, or the reinforcing fibers will break off, which will deteriorate the quality of the prepreg. Become.

[Purpose of the invention]

An object of the present invention is to provide a prepreg manufacturing method that can increase the transfer speed of stacked bodies or consistently obtain uniform resin impregnation and smoothness even when manufacturing thick prepregs. It's about doing.

[Structure of the invention]

To achieve the above object, the present invention superimposes sheets on both sides of a sheet-like reinforcing fiber, each of which has at least one resin-supporting sheet, and presses the superimposed body with an impregnated roll to transfer the resin to the reinforcing fiber. When transferring and impregnating, the impregnation rolls are provided in multiple stages in the transport direction of the stacked body, and the linear pressure of the multi-stage impregnation rolls is increased as the rolls are located downstream in the transport direction of the stacked body. It is characterized by this.

In the present invention, reinforcing fibers refer to high-strength, high-modulus fibers such as carbon fibers, glass fibers, organic high-modulus fibers (such as polyaramid fibers), silicone carbide fibers, alumina fibers, and boron fibers. These fibers are usually used in the form of strands, and even if only one type is used,
Alternatively, two or more types of reinforcing fibers, such as carbon fibers and glass fibers, carbon fibers and organic high-elastic fibers, etc., may be used in combination by arranging them regularly or irregularly in the width direction of the prepreg. Note that the reinforcing fibers may be processed in advance into a sheet form such as mat or fabric.

A resin-supported sheet is a sheet that supports resin on one side.The base sheet is paper such as kraft paper, roll paper, glassine paper, etc. with a thickness of about 0.05 to 0.2 mm, and cream, starch, etc. , a coating layer of a filler such as polyethylene, polyvinyl alcohol, etc. is provided, and a silicone or non-silicone mold release agent, preferably a condensation reaction type of polydimethylsiloxane and polydimethylhydrodienesiloxane, is provided on each coating layer. Alternatively, a release paper coated with a release agent made of addition reaction type silicone is preferably used.

The sheet serves to prevent the arrangement of reinforcing fibers from being disturbed in the prepreg manufacturing process and to prevent resin from adhering to rolls and the like. Also,
After prepreg manufacturing is completed, it is bonded to the prepreg and serves to prevent reinforcing fibers from becoming disordered and protect them from moisture absorption until they are peeled off for final use such as FRP. .

The resin supported on the sheet includes epoxy resin, unsaturated polyester resin, phenol resin,
Thermosetting resins such as polyimide resins are preferably used. These resins are in a B-stage (semi-cured) state while being supported on the sheet.
The amount of resin supported is for unidirectional prepreg,
It is preferable that the amount of resin impregnated in the finally obtained prepreg is 20 to 70% by weight, more preferably 30 to 50% by weight. Note that it is preferable that the resin be supported on the sheet by coating.

The impregnating roll usually consists of a pair of heating rolls and nip rolls, and functions to spread the reinforcing fibers, transfer the resin supported on the resin carrying sheet to the reinforcing fibers, and impregnate the reinforcing fibers. The heating temperature is preferably 80 to 180°C, more preferably 90 to 150°C. Further, it is preferable that the pressure applied by the impregnating roll to the stacked body composed of the reinforcing fibers and the resin support sheet is several kilograms per cm in linear pressure. The impregnating rolls are provided in multiple stages in the transport direction of the stacked body, and the linear pressure needs to be increased as the rolls move downstream in the transport direction, and the number of stages is preferably from 2 to 5 stages.

In the case of unidirectional prepreg, the thickness of the prepreg is preferably 0.02 to 1 mm, more preferably
0.03~05mm is good. Further, it is preferable that the content of the reinforcing fibers is 30 to 80% by weight, more preferably 50 to 70% by weight.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following will explain the process diagrams for carrying out the present invention shown in the drawings.

In the figure, reference numeral 1 denotes a reinforcing fiber package, from which stride-shaped reinforcing fibers 2 are drawn out in one direction in parallel to each other in a sheet-like arrangement. 3 and 4 are rolls of resin carrying sheets, respectively, and the resin carrying sheets 5 and 6 pulled out from the respective rolls 3 and 4 are superimposed on both sides of the reinforcing fibers 2. The resin-carrying sheets 5 and 6 are stacked so that the resin-coated surfaces face the reinforcing fibers 2. However, in the present invention, either one of the two upper and lower resin-supporting sheets may be a sheet that does not support resin.
That is, the resin-supported sheet may be superimposed on either side of the sheet-like reinforcing fiber.

The superposed body of reinforcing fibers 2 and resin-supporting sheets 5 and 6 is heated and pressurized in sequence by impregnating rolls 9 consisting of heating rolls 7 and nip rolls 8 provided in three stages, and the linear pressure increases as it goes downstream. added and pressure treated. For example, in the first stage, 2 to 3
It is preferable to pressurize with a linear pressure in the range of Kg/cm, 2.5 to 4.5 Kg/cm in the second stage, and 3 to 7 Kg/cm in the third stage.

Due to the pressure treatment of the multi-stage impregnation rolls 9, the reinforcing fibers 2 in the stride form are gradually spread out into a flat shape in each stage, and the resin supported on the resin support sheets 5 and 6 is also pushed out and spread out. It transfers to the reinforcing fibers 2 and is impregnated inside. Figure 2 shows how the resin impregnation changes, and after being treated with the first stage impregnating roll 9, the cross section of the reinforcing fibers 2 is still round as shown in Figure 2A. It is in a state close to its shape, and the resins 5a and 6a of the resin support sheets 5 and 6 have only slightly transferred to the reinforcing fibers 2, and both sides are covered with the sheets 5b and 6b of the resin support sheets 5 and 6, respectively. It has become a state of being. Then, when treated with the second stage impregnation roll 9, as shown in FIG. 2B,
The reinforcing fibers 2 are expanded into a flat shape, and the reinforcing fibers 2 are impregnated with the resins 5a and 6a of the resin carrying sheets 5 and 6. Furthermore, after being treated with the third stage impregnating roll 9, as shown in FIG. 2C,
The reinforcing fibers 2 are further expanded, and adjacent ones are integrated to the extent that the boundaries are not visible. Further, the resins 5a and 6a are completely and uniformly impregnated into the reinforcing fibers 2, resulting in a smooth state.

As described above, in the stacked body in which the reinforcing fibers 2 are impregnated with resin, only the sheet 5b of the upper resin carrying sheet 5 is peeled off, and the remaining stacked body is made up of the prepreg 1 together with the sheet 6b on the resin carrying sheet 6 side.
0 and is rolled up into the product package 11.

In the pressure treatment using the multistage impregnation rolls 9 described above, an excessively large linear pressure is not applied at once, and the impregnation treatment is performed while gradually increasing the linear pressure from a low linear pressure to a high linear pressure, thereby reinforcing the material. The fibers 2 are gradually expanded and no single yarn breakage occurs. Furthermore, since the resin is impregnated following the reinforcing fibers 2 that are gradually being expanded, the entire fibers are uniformly impregnated and smoothed. This effect is even more remarkable when increasing the transport speed of the stacked bodies to improve productivity or when producing thick prepregs.

Example 1 Carbon fiber "Torayca" T-300 manufactured by Toray Industries, Inc. was used as the reinforcing fiber, and epoxy resin was used as the resin. By the method shown in Fig. 1, a material with a thickness of approximately 0.28 mm and a resin content of A unidirectional prepreg with about 40% weight was made. However, the linear pressure of the impregnating roll is approximately 2 kg/cm at the first stage and approximately 3.5 kg/cm at the second stage.
Kg/cm, and the third stage was approximately 4.5 Kg/cm, and the temperature of the impregnating roll was set at 120°C in both stages. Furthermore, the transport speed of the stacked body of carbon fiber and resin support sheet was set to 8 m/min.

The surface smoothness of the obtained prepreg was visually confirmed. In addition, the cross section was observed under a microscope to examine the state of resin impregnation. As a result, both the smoothness and the resin impregnation state were extremely good.

Example 2 In Example 1, the transfer speed of the stacked body was set to approximately
Although the speed was increased to 12 m/min, no change was observed in the smoothness or resin impregnation state.

Comparative Example 1 A sample was produced in exactly the same manner as in Example 1 except that only one impregnated roll was used. However, the linear pressure of the impregnated roll was set at 6 kg/cm.

The obtained prepreg had the same surface smoothness as that of Example 1. However, the state of impregnation of the reinforcing fibers with the resin was uneven, and many voids were observed.

Comparative Example 2 In Example 1 above, when the transfer speed of the stacked body was increased to about 12 m/min, both the surface smoothness and the resin impregnation state became significantly poor.

〔Effect of the invention〕

As described above, the present invention involves stacking sheets on both sides of a sheet-shaped reinforcing fiber, each of which is a resin-supporting sheet, and pressing this stacked body with an impregnated roll to transfer the resin to the reinforcing fiber. When impregnating, impregnation rolls are provided in multiple stages in the transport direction of the stacked body, and the linear pressure of the multi-stage impregnation rolls is increased as the downstream side of the stacked body is conveyed. Even at high speeds or in the case of thick prepregs, smooth and uniform resin impregnation can be performed without single filament breakage.

[Brief explanation of the drawing]

Figure 1 is a process diagram for implementing the present invention, Figure 2 is a process diagram for carrying out the present invention.
Figures A, B, and C are AA and B- in Figure 1, respectively.
It is a sectional view taken along B, CC cross section. 2... Reinforcing fiber, 5, 6... Resin support sheet, 7...
Heating roll, 8...Nippro roll, 9...Impregnation roll.

Claims (1)

[Claims] 1. Layer sheets on both sides of a sheet-shaped reinforcing fiber, each of which is a resin-supporting sheet, and press the stacked body with an impregnating roll to transfer and impregnate the reinforcing fiber with the resin. A method for manufacturing prepreg, which comprises providing multiple impregnating rolls in multiple stages in the direction of transport of the stacked body, and performing pressure treatment by increasing the linear pressure of the multi-stage impregnation rolls on the downstream side in the direction of transport of the stacked body.