JP4076241B2 - Manufacturing method of fiber reinforced plastic molding - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for easily and efficiently producing a fiber-reinforced plastic molded article.
[0002]
[Prior art and problems to be solved by the invention]
Since fiber reinforced plastics are lightweight and have high strength, they are widely used in automobile and aircraft structural members.
[0003]
It is necessary to combine a plurality of fiber reinforced plastic parts when manufacturing a fiber reinforced plastic molded product having a complicated shape. As a method for manufacturing such a fiber reinforced plastic molded product, a resin injection molding method, a resin transfer molding method, etc. Is mentioned. These methods are methods for producing a fiber-reinforced plastic by injecting a resin into dry reinforcing fibers later, and are excellent in production efficiency. However, since the resin is impregnated, a large-sized molded product or a special-shaped molded product takes time to impregnate, and there is a problem that voids remain in the product.
[0004]
On the other hand, in a molding method using a woven fabric made of reinforcing fibers impregnated with a thermosetting resin in advance (so-called “prepreg sheet”), the molding process is mainly manual work, so the productivity is low and the manufacturing cost is low. There is a problem that it is expensive. In addition, in order to manufacture a molded product having a more complicated shape, each molded part must be assembled by bonding, bolts, rivets or the like.
[0005]
Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a method for producing a fiber-reinforced plastic molded product easily and efficiently without requiring an adhesive, bolts, rivets and the like.
[0006]
[Means for Solving the Problems]
As a result of earnest research in view of the above object, the present inventors, after heat-treating at least one fiber reinforced plastic member constituting the fiber reinforced plastic molded product to a semi-cured state in the mold, It was discovered that a fiber-reinforced plastic molded article can be manufactured simply and efficiently with high reliability by close contact and heat treatment, thereby completing the present invention.
[0007]
That is, according to the first method for producing a fiber-reinforced plastic molded product of the present invention, a preform composed of a plurality of reinforced fiber woven fabrics is prepared, and a curing rate of 10 to 40 % is obtained after impregnation with a thermosetting resin. the at least one first fiber-reinforced plastic member by heat treatment to a semi-cured state, to produce at least one second fiber-reinforced plastic member, said first fiber-reinforced plastic member, said first The first and second fiber reinforced plastic members are integrated by heat-treating in close contact with the second fiber reinforced plastic member and completely curing the thermosetting resin.
According to the second method for producing a fiber-reinforced plastic molded article of the present invention, a preform composed of a plurality of reinforced fiber woven fabrics is prepared, and after impregnating a thermosetting resin in the mold, a curing rate of 10 to 40 % is obtained. At least one first fiber reinforced plastic member is produced by heat treatment until a cured state is obtained, and a second fiber reinforced plastic member is produced by laminating a plurality of prepreg sheets. The first and second fiber-reinforced plastic members are integrated by heat-treating the member in close contact with the second fiber-reinforced plastic member and completely curing the thermosetting resin. To do.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The fiber-reinforced plastic molded article produced by the method of the present invention comprises at least one first fiber-reinforced plastic member heat-treated in a semi-cured state and at least one second fiber-reinforced plastic member.
[0009]
[1] Fiber-reinforced plastic member in semi-cured state The first fiber-reinforced plastic member is obtained by impregnating a reinforcing fiber with a thermosetting resin in a mold and making it semi-cured by heat treatment. When the second fiber-reinforced plastic member is in a semi-cured state, the reinforcing fiber is impregnated with a thermosetting resin in the mold and made into a semi-cured state by heat treatment, or the prepreg is made into a semi-cured state by heat treatment It can be.
[0010]
(1) Reinforcing fiber The reinforcing fiber used in the present invention is preferably a carbon fiber, an aramid fiber, a glass fiber, or a mixed weave thereof. The diameter of the reinforcing fiber is preferably about 3 to 200 μm. The reinforcing fibers are preferably used in a woven state, and a plurality of reinforcing fiber woven fabrics are preferably laminated. Before impregnating the thermosetting resin in the mold, it is preferable to perform stitching, partial adhesion, etc. in order to maintain the integral shape of the reinforcing fibers. Alternatively, a three-dimensional woven fabric matching the shape can be used. FIG. 1 shows an example in which a plurality of reinforcing fibers are integrated into a T shape by stitching. In this embodiment, a woven fabric of reinforcing fibers integrated in a T-shape (preform 1) is composed of a vertical portion 1a and a horizontal portion 1b, and the shape is maintained by stitches 2 near the end of each portion. Yes.
[0011]
(2) The thermosetting resin impregnated in the thermosetting resin preform 1 is preferably an epoxy-based and / or bismaleimide-based thermosetting resin. Examples of commercially available epoxy thermosetting resins include PR-500 manufactured by 3M, and examples of commercially available bismaleimide thermosetting resins include 5250-4-RTM manufactured by CYTEC.
[0012]
The preform 1 is impregnated with a thermosetting resin by a resin transfer molding method or the like. In detail, first, the preform 1 is placed in a cavity of a mold, and after the mold is clamped, a thermosetting resin is injected and impregnated. The ratio between the reinforcing fiber and the thermosetting resin is preferably in the range of 40/60 to 60/40 by volume. If the weight ratio of reinforcing fiber / thermosetting resin is less than 40/60, the mechanical strength of the resulting fiber-reinforced plastic molded product is insufficient, and if it exceeds 60/40, it is difficult to impregnate the resin. It becomes difficult to integrally hold the reinforced plastic molded product.
[0013]
(3) Heat treatment The preform 1 impregnated with the thermosetting resin is heat-treated until it becomes semi-cured. The heat treatment conditions are generally set so that the thermosetting resin is in a semi-cured state. Here, the “semi-cured state” is a state in which the thermosetting resin is solid and non-sticky at room temperature and is easy to handle, but when further heat-treated, the thermosetting resin is completely cured after reflowing. Say. In a semi-cured state is cured of the thermosetting resin of the fiber reinforced plastic member in (ratio of the cured resin to the total thermosetting resin) 10 to 40%. If the curing rate is less than 10%, it is not sufficiently solid and is not easy to handle because it is sticky. On the other hand, when the curing rate exceeds 40%, the adhesion with other fiber-reinforced plastic members becomes insufficient in the subsequent curing step, and the peel strength of the molded product is lowered.
[0014]
In order to obtain a fiber reinforced plastic member in a semi-cured state, in the case of an epoxy thermosetting resin, it is preferable to heat-treat at 120 to 130 ° C. for 80 to 120 minutes or 130 to 140 ° C. for 30 to 60 minutes, In the case of a bismaleimide-based thermosetting resin, it is preferable to perform heat treatment at 115 to 125 ° C. for 60 to 90 minutes or at 135 to 145 ° C. for 30 to 60 minutes.
[0015]
FIG. 2 shows an example of a semi-cured fiber reinforced plastic member 4 obtained from the preform 1 of FIG. The semi-cured fiber reinforced plastic member 4 thus obtained is solid and non-sticky near room temperature, is easy to handle and has good storage stability.
[0016]
[2] Fiber-reinforced plastic molded products
(1) Combination of fiber reinforced plastic members In the present invention, at least one semi-cured fiber reinforced plastic member is integrated with at least one other fiber reinforced plastic member. Street.
(1) All the fiber reinforced plastic members to be integrated are obtained by impregnating a reinforcing fiber with a thermosetting resin in a mold and then making it semi-cured by heat treatment.
(2) A combination of at least one semi-cured fiber reinforced plastic member and at least one reinforced fiber prepreg. Here, the reinforced fiber prepreg is a laminate of reinforced fiber woven fabrics impregnated with a thermosetting resin in advance, and the thermosetting resin may be in a semi-cured state by heat treatment.
[0017]
(2) Manufacturing Method FIG. 3 shows an example of joining plate-like and T-shaped semi-cured fiber reinforced plastic members, respectively, as one embodiment of the present invention. A sealing material 14 is laid around a plate-like fiber-reinforced plastic member (plate-like member) 12 placed on the surface plate 10, and a T-shaped fiber-reinforced plastic member is placed at a predetermined position of the plate-like member 12. (T-shaped member) 4 is arranged. In order to prevent the T-shaped member 4 from being deformed, an appropriate jig 18 is disposed on the L-shaped portion of the T-shaped member 4. A bagging film 20 having a vacuum suction port (not shown) is covered from above so as to cover the entire plate-like member 12 and T-shaped member 4, and bonded to the sealing material 14. The bagging film 20 is preferably a heat resistant film such as a nylon film, a polyimide film, or a polyamide film. Further, as the sealing material 14, a butyl rubber type or silicon rubber type can be used. The sealing material 14 is preferably used in the form of a sheet or tape.
[0018]
The inside of the bagging film 20 is depressurized by evacuation, and the plate member 12 and the T-shaped member 4 are brought into close contact with each other. In this state, heat treatment is performed at 180 to 190 ° C. for 120 to 150 minutes. By this heat treatment, the semi-cured thermosetting resin in the plate-like member 12 and the T-shaped member 4 is reflowed, and both are completely integrated.
[0019]
As mentioned above, although the manufacturing method of this invention was demonstrated, this invention is not limited to it, A various change can be added unless the meaning of this invention is changed. For example, in order to improve heat resistance of bismaleimide or the like which is a thermosetting resin, after-curing may be performed on a fiber-reinforced plastic molded article at 220 to 240 ° C. for 4 to 6 hours.
[0020]
【Example】
The present invention will be described in detail by the following examples and comparative examples, but the present invention is not limited thereto.
[0021]
Example 1
First, as shown in FIG. 1, a carbon fiber woven fabric was laminated in a T shape, and the vicinity of the end portion was stitched to create a preform 1. The number of carbon fiber woven fabrics laminated was 12 on the vertical part (eight of which were unidirectional materials) and 12 on the bottom (eight of which were unidirectional materials). Preform 1 was placed in a mold, and epoxy thermosetting resin PR-500 (manufactured by 3M) was injected at 120 to 135 ° C. to impregnate preform 1.
[0022]
Preform 1 impregnated with an epoxy thermosetting resin in the mold was heated at 135 to 140 ° C. for 45 minutes, and heat treatment was performed so that the curing rate of the thermosetting resin was 30%. The curing rate of the thermosetting resin was determined by DSC thermal analysis. When the obtained T-shaped fiber reinforced plastic member 4 was cooled to room temperature, it was integrated in a solid state, and the surface was not sticky at all.
[0023]
A plate-like fiber reinforced plastic member 12 was prepared by laminating four prepreg sheets made of carbon fiber woven fabric with an epoxy thermosetting resin PR-500. The T-shaped member 4 and the plate-shaped member 12 were combined in the arrangement shown in FIG. 3, the jig 18 was arranged in the L-shaped portion of the T-shaped member 4, and then the whole was covered with the bagging film 20. In this state, it was placed in an autoclave and heat treated at 180 ° C. for 2 hours while reducing the pressure in the bagging film 20 to produce a fiber reinforced plastic molded product 22 (FIG. 4).
[0024]
The obtained fiber-reinforced plastic molded product 22 was firmly integrated, and the peel strength between the T-shaped member 4 and the plate-like member 12 was almost the same as the breaking strength of each member.
[0025]
【The invention's effect】
As described above in detail, according to the method of the present invention, since a plurality of fiber reinforced plastic members including at least one semi-cured fiber reinforced plastic member are heat-treated to manufacture an integrally molded product, an adhesive or bolt No rivets or the like are required, and the obtained molded product has high reliability with respect to mechanical strength. According to the method of the present invention, even a fiber reinforced plastic molded product having a complicated shape can be easily manufactured by combining a semi-cured fiber reinforced plastic member having a simple shape, thereby reducing the manufacturing cost and increasing the efficiency. Can be achieved.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a preform made of reinforcing fibers manufactured according to an embodiment of the present invention.
2 is a schematic perspective view showing a T-shaped semi-cured fiber reinforced plastic member obtained from the preform of FIG. 1; FIG.
FIG. 3 is a schematic cross-sectional view showing a method for integrally joining the fiber-reinforced plastic member and the prepreg sheet laminate of FIG. 2;
FIG. 4 is a schematic perspective view showing a fiber-reinforced plastic molded article obtained by the method of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Preform 2 ... Stitch 4 ... The fiber reinforced plastic member of a semi-hardened state
12 ... Plate-like fiber reinforced plastic member (prepreg sheet laminate)
14 ... Sealing material
18 ... Jig
20 ... Bagging film
22 ・ ・ ・ Fiber-reinforced plastic molded product

Claims (6)

  In a method for producing a large fiber reinforced plastic molded article, a preform made of a plurality of reinforced fiber woven fabrics is prepared, and after impregnating with a thermosetting resin in a mold, it is in a semi-cured state with a curing rate of 10 to 40% By heat-treating until at least one first fiber reinforced plastic member and at least one second fiber reinforced plastic member are produced, the first fiber reinforced plastic member is used as the second fiber reinforced plastic. A method for producing a fiber-reinforced plastic molded article, wherein the first and second fiber-reinforced plastic members are integrated by heat-treating in close contact with the member and completely curing the thermosetting resin. .   In a method for producing a large fiber reinforced plastic molded article, a preform made of a plurality of reinforced fiber woven fabrics is prepared, and after impregnating with a thermosetting resin in a mold, it is in a semi-cured state with a curing rate of 10 to 40% At least one first fiber reinforced plastic member is produced by heat treatment until a second fiber reinforced plastic member is produced by laminating a plurality of prepreg sheets, and the first fiber reinforced plastic member is Fiber reinforced, wherein the first and second fiber reinforced plastic members are integrated by heat-treating in close contact with the second fiber reinforced plastic member and completely curing the thermosetting resin. Manufacturing method of plastic molded products.   3. The method for manufacturing a fiber-reinforced plastic molded article according to claim 2, wherein the second fiber-reinforced plastic member is in a semi-cured state.   The method for manufacturing a fiber-reinforced plastic molded article according to claim 2, wherein the second fiber-reinforced plastic member is in an uncured state.   The method for producing a fiber-reinforced plastic molded product according to any one of claims 1 to 4, wherein the reinforcing fiber is at least one selected from the group consisting of carbon fiber, aramid fiber, and glass fiber. Method.   The method for producing a fiber-reinforced plastic molded product according to any one of claims 1 to 5, wherein the thermosetting resin is an epoxy-based and / or bismaleimide-based thermosetting resin.

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