JP5240754B2 - Method for producing fiber reinforced composite - Google Patents

Description

  The present invention relates to a method for producing a fiber-reinforced composite made of a material reinforced by impregnating a fiber body with a resin solution dissolved in a solvent.

  4 and 5 show a conventional method for producing a fiber-reinforced composite using a resin containing a solvent. As shown in FIG. 4, a unidirectional or woven reinforcing fiber (1) is impregnated with a resin (5) containing a solvent and heated in an oven (12) to remove the solvent (dry). A prepreg (a precursor of a fiber-reinforced composite) (16) is obtained by winding up the reinforcing fiber (1) after removal of the solvent and the release paper or film (15). Thereafter, as shown in FIG. 5, the prepreg (16) cut into the shape, fiber orientation and amount required for the surface plate or the mold (2) is laminated and formed. A fiber reinforced composite (11) is obtained by a press machine (compression molding machine) or an autoclave (pressure vessel) (9) by high pressure of 1 MPa or more and heating.

  In the conventional manufacturing method, the prepreg (16) after solvent removal is used. Due to problems such as high viscosity of the prepreg (16), low adhesion (tackiness), and formation of a gap between the prepregs (16), the prepreg (16) press machine (compression molding machine) and autoclave (pressure vessel) ( 9) A high-quality fiber-reinforced composite (11) could not be obtained unless a high pressure of 1 MPa or higher was used during curing. "Non-patent documents 1 and 2"

FAROUK A, KWON TH, “EFFECT OF PROCESSING PARAMETERS ON COMPRESSION MOLDED PMR-15 / C3K COMPOSITES”, POLYMER COMPOSITES 11 (6): 379-386 DEC 1990 BOWLES KJ, FRIMPONG S, “VOID EFFECTS ON THE INTERLAMINAR SHEAR-STRENGTH OF UNIDIRECTIONAL GRAPHITE-FIBER-REINFORCED COMPOSITES”, JOURNAL OF COMPOSITE MATERIALS 26 (10): 1487-1509 1992

Moreover, the viscosity of the prepreg (16) is high, and the resin (5) may fall off from the reinforcing fiber (1) in the process of laminating and molding the prepreg (16) on the curved or complex-shaped mold (2). In addition, it is difficult to produce a fiber-reinforced composite (11) having a complicated shape and to control the fiber content.
If the solvent removal (drying) in the oven (12) was insufficient, the viscosity of the prepreg (16) was low, and it was difficult to laminate the prepreg (16) cut into the required shape, fiber orientation and amount. .
Resin (5) flowed out, and it was difficult to control the fiber content of the fiber-reinforced composite (11).
Further, removal of the solvent in the oven (12) (drying) sometimes produced voids (voids) accompanying the heating of the prepreg (16).
Two separate manufacturing steps were required to use the prepreg (16).

  In view of such circumstances, the present invention has an object to provide a manufacturing method that can be easily formed into a desired shape, and that the generation of voids is dramatically reduced as compared with the prior art.

The manufacturing method of the fiber reinforced composite of the invention 1 is a method of manufacturing a fiber reinforced composite made of a material reinforced by impregnating a unidirectional or woven reinforcing fiber body with a polyimide resin solution dissolved in a solvent. ,
While impregnating the resin solution at VaRTM (vacuum impregnation) method on the fiber body was typed into the desired shape, the degree of vacuum in the VaRTM method is a less -0.09 MPa, the temperature is brought to room temperature, subsequently, in vacuum condition and heated, thereby removing the solvent, the temperature at the removal of the solvent in the range of the solvent evaporation temperature (evaporation temperature) ÷ 2 ± 20 ℃, after that, the fibrous body When the impregnated resin is cured , pressurization is performed at a pressure of less than 1 MPa .

According to the invention 1, by molding the fiber body before resin impregnation, it has become possible to process into a highly accurate shape that is not desired in the past, by processing much easier than conventional prepreg molding.
Further, even in the final curing process, it has become possible to achieve a favorable one with few voids despite the low pressure curing of less than 1 MPa, which could not be expected in the past.

Further, according to the invention 1, by curing at a low pressure of less than 1 MPa, high-pressure treatment is not required in the entire manufacturing process of the fiber reinforced composite, and the productivity and process safety can be improved. In addition, such low-pressure curing can eliminate the deformation of the already molded shape and obtain a fiber-reinforced composite according to the expected shape.

  As described above, according to the present invention, even in a fiber reinforced composite using a resin containing a solvent, a fiber reinforced composite having a good quality (low in defects and voids) can be obtained at a low pressure of less than 1 MPa in the curing step. effective.

  FIG. 1 is a diagram showing an example of a method for producing a fiber reinforced composite using a resin containing a solvent according to the present invention. In this figure, a unidirectional or woven reinforcing fiber (1) is on a surface plate, a curved surface or a molding die (2) having a complicated shape, and a frame plate (3) and a transparent or translucent backing plate (4). In the arranged state, the preparation from the resin (5) containing the solvent for impregnating the resin based on the VaRTM (vacuum impregnation) method to the resin inlet (6) and the excess resin from the vacuum inlet (7) or Preparations have been made for the vacuum connection port (10) of the autoclave (pressure vessel) (9) through the container resin (8) for accumulating the solvent. The resin impregnation step is started, and the state in which the reinforcing fiber (1) is impregnated with the resin (5) containing the solvent is visually confirmed. After completion of the impregnation, a solvent removing step and a curing step at a low pressure of less than 1 MPa are continuously performed in the autoclave (9). By this production method, a fiber-reinforced composite (11) with good quality (with few defects and voids) can be obtained.

In the VaRTM (vacuum impregnation) method, since the reinforcing fiber (1) is impregnated with the resin (5) containing the solvent by evacuation, the degree of vacuum is −0.09 MPa or less, and the resin is removed by removing the solvent. In order to avoid an increase in viscosity, the temperature in this process is preferably room temperature.
When removing the solvent, the degree of vacuum is the same as the degree of impregnation, the temperature is lower than the evaporation temperature of the solvent, and it is necessary to reduce the solvent removal time and suppress the generation of voids due to solvent volatilization. Evaporation temperature) is preferably in the range of 2 ± 20 ° C.
Furthermore, at the time of curing, it is desirable that the pressure in the autoclave (9) is less than 1 MPa, and it is 0.9 MPa or less that can be cured even by the JIS Occupational Safety and Health Act (Type 2 pressure vessel).
In addition, there is no restriction | limiting in the material, resin, and solvent which can be applied to the said process, What was used for the conventional fiber reinforced composite body (11) can be used similarly.
In addition, a fiber / resin combination (combination of high-rigidity carbon fiber and polyimide resin such as PMR-15) that has not been used because the prepreg (16) is too hard in the prior art is also used in the present invention. It became possible to shape | mold into a fiber reinforced composite body (11) by this.

FIG. 2 is a figure which shows the Example of the manufacturing method of the fiber reinforced composite body (11) using the resin containing the solvent by this invention. In this figure, the unidirectional reinforced carbon fiber (K13D2U: Mitsubishi Chemical Industries) (1) is on the surface plate (2) for VaRTM, and the frame plate (3) and the glass backing plate (4) are arranged. , A polyimide resin solution containing a solvent for impregnating a resin based on the VaRTM (vacuum impregnation) method (sky bond 703 manufactured by IST Corporation, the solvent is NMP: N methylpyrrolidone, and the evaporation temperature is 200 ° C. ) Preparation from (5) to the resin inlet (6) and preparation from the vacuum port for VaRTM (7) to the vacuum connection port (10) through the container (8) for storing excess resin or solvent are made. .
The resin impregnation step is started, and a state in which the reinforcing fiber (1) is impregnated with the polyimide resin (5) containing a solvent is visually confirmed. The degree of vacuum during impregnation was -0.098 ± 0.002 MPa, and the temperature was 25 ± 5 ° C. After completion of the impregnation, the solvent removal step is performed by heating to 90 ± 10 ° C. in an oven (12) with the vacuum drawn. After completion of the solvent removal step, the reinforcing fiber (1) containing the polyimide resin is removed from the surface plate (2). Vacuuming is performed in an autoclave (9), and a curing step is performed at a low pressure of 0.7 MPa.

  FIG. 3 shows a cross-sectional observation (14) of a fiber reinforced composite (13) and a carbon fiber reinforced composite using a solvent-containing resin prepared according to an embodiment of the present invention. The void content was 1.0% by volume or less from the results of the cross-sectional observation (14) and the void (void) rate measurement results. Moreover, the result of using different types of unidirectional carbon fibers (T1000GB: Toray) / woven carbon fibers (CO6343: Toray) was the same.

The flow which shows the process from the impregnation of an Example to solvent removal with the schematic of an apparatus used. The flow which shows the hardening process of an Example with the schematic of an apparatus used. The photograph which shows the sheet-like fiber reinforced composite_body | complex obtained by the Example. The flow which shows the manufacturing process of the conventional prepreg. The flow which shows the manufacturing process from the cutting of conventional prepreg, lamination to autoclave hardening.

Explanation of symbols

(1) unidirectional or woven reinforcing fiber,
(2) Surface plate or curved or curved mold
(3) Frame plate,
(4) Transparent or translucent patch plate,
(5) Resin containing solvent,
(6) Resin injection port,
(7) Vacuum outlet,
(8) Container for storing excess resin or solvent,
(9) autoclave,
(10) Vacuum connection port,
(11) Fiber reinforced composite,
(12) oven,
(13) A fiber-reinforced composite using a resin containing a solvent prepared according to Examples,
(14) Cross-sectional observation of carbon fiber reinforced composite,
(15) Release paper or film,
(16) Prepreg.
In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

A method for producing a fiber reinforced composite comprising a material reinforced by impregnating a unidirectional or woven reinforcing fiber body with a polyimide resin solution dissolved in a solvent,
While impregnating the resin solution at VaRTM (vacuum impregnation) method on the fiber body was typed into the desired shape, the degree of vacuum in the VaRTM method is a less -0.09 MPa, the temperature is room temperature,
Subsequently, the solvent is removed by heating in a vacuum state, and the temperature at the solvent removal is in the range of (evaporation temperature) ÷ 2 ± 20 ° C. with respect to the solvent evaporation temperature,
As after, when curing the resin impregnated into the fibrous body, method for producing a fiber-reinforced composite, wherein the pressurized below 1 MPa.