JP7073811B2 - Method for manufacturing fiber-reinforced composite molded products - Google Patents

Description

The present invention relates to a method for manufacturing a fiber-reinforced composite material molded product.

Fiber reinforced composite molded products are widely used as members for sports, automobiles, aircraft, industrial applications, and the like. In particular, carbon fiber reinforced composite material molded products (CFRP) are being actively adopted in fields where light weight and high mechanical properties are required.

As a method for producing a fiber-reinforced composite material molded product, a method of compression molding a fiber-reinforced composite material is widely used. As the fiber-reinforced composite material, a prepreg in which a reinforced fiber base material containing continuous fibers is impregnated with a thermosetting resin composition, and a sheet molding in which a reinforced fiber base material containing short fibers is impregnated with a thermosetting resin composition. Compound (SMC) or the like is used.

Since SMC has a short fiber length of the reinforcing fiber, the strength of the molded product is generally lower than that of the prepreg, but it is suitable for molding a complicated shape such as a ridge. For example, an SMC is placed in a portion of a molding die that forms a complicated shape such as a ridge, a prepreg that forms a substrate is further placed on the SMC, and the fiber-reinforced composite material is compression-molded by heating and pressurizing. Obtain a molded product (Patent Document 1).

Japanese Unexamined Patent Publication No. 2013-72055

Generally, a prepreg resin composition having a low fluidity is used to ensure mechanical properties, and an SMC resin composition is used to have a high fluidity to ensure shape followability. Therefore, in the method as in Patent Document 1, the difference in the resin composition between the prepreg and SMC, the variation in the length and orientation of the fibers may affect, and the obtained molded product may be warped, resulting in poor dimensional accuracy. Tend.

If the same resin composition is used for the prepreg and SMC, the problem of warpage can be improved to some extent, but since the resin composition that can achieve both mechanical properties and shape-following properties, which are contradictory properties, is limited, the degree of freedom in molding is limited. descend. It is also difficult to control the fiber orientation of SMC according to the fiber orientation of the prepreg to suppress the warp.

It is an object of the present invention to provide a method for producing a fiber-reinforced composite material molded product capable of producing a fiber-reinforced composite material molded product having high dimensional accuracy in which the occurrence of warpage is suppressed by molding using a prepreg and SMC. ..

The present invention has the following configurations.
[1] A composite in which a prepreg layer containing a reinforcing fiber and a resin composition is laminated on both the first surface side and the second surface side in the thickness direction of a sheet molding compound layer containing the reinforcing fiber and the resin composition. A method for manufacturing a fiber-reinforced composite material molded product for molding a laminate.
[2] The prepreg layer is arranged in a frame shape along the outer peripheral end of the sheet molding compound layer on both the first surface side and the second surface side of the sheet molding compound layer, and the composite laminate is formed. The method for producing a fiber-reinforced composite material molded product according to [1], which forms a body.
[3] The ratio of the area occupied by the prepreg layer laminated on the first surface side of the sheet molding compound layer to the area of the first surface of the sheet molding compound layer _Q1 and the sheet molding compound layer. The ratio of the area occupied by the prepreg layer laminated on the second surface side of the sheet molding compound layer to the area of the second surface Q2 is the same as _Q2 and is 10% or more, [1] or [ 2] The method for manufacturing a fiber-reinforced composite material molded product according to.
[4] The width of the frame portion of the frame-shaped prepreg layer arranged on each of the first surface side and the second surface side of the sheet molding compound layer is the same and is 10 mm or more [2]. Alternatively, the method for producing a fiber-reinforced composite material molded product according to [3].
[5] Described in any one of [1] to [4], wherein the reinforcing fibers contained in the prepreg layer arranged on the first surface side and the second surface side of the sheet molding compound layer are continuous fibers. How to manufacture fiber reinforced composite molded products.
[6] The method for producing a fiber-reinforced composite material molded product according to any one of [1] to [5], wherein the composite laminate is compression-molded with a molding die.

According to the present invention, a fiber-reinforced composite material molded product having high dimensional accuracy in which the occurrence of warpage is suppressed can be obtained by molding using a prepreg and SMC.

It is a top view which showed an example of the composite laminated body in the manufacturing method of the fiber-reinforced composite material molded article of this invention. FIG. 3 is a cross-sectional view taken along the line II of the composite laminate of FIG. It is sectional drawing which showed an example of the composite laminated body in the manufacturing method of the fiber-reinforced composite material molded article of this invention. It is a top view which showed the rectangular frame-shaped prepreg produced in Example 1. FIG. It is sectional drawing which showed the composite laminated body produced in the comparative example 1. FIG. It is a top view explaining the measurement point of the warp evaluation of an Example and a comparative example.

The fiber-reinforced composite material molded product of the present invention (hereinafter, also simply referred to as “molded product”) is a sheet molding compound (hereinafter, also referred to as “SMC”) containing the reinforcing fiber and the resin composition in the thickness direction. This is a method for forming a composite laminate in which a prepreg layer containing a reinforcing fiber and a resin composition is laminated on both the first surface side and the second surface side.

The prepreg layer is a layer formed by a sheet-shaped prepreg containing reinforcing fibers and a resin composition. The prepreg layer may be a single layer composed of one prepreg, or may be a plurality of layers composed of two or more prepregs.

As the reinforcing fiber contained in the prepreg, continuous fiber is preferable. The continuous fiber is a reinforcing fiber having a fiber length of 76.2 mm or more.
The form of the prepreg may be a UD prepreg in which continuous fibers are aligned in one direction, or a cross prepreg in which continuous fibers are woven so as to be orthogonal to each other. In addition, a prepreg based on a reinforcing fiber cloth such as a bias cloth, a triaxial cloth, or a Multi-axial Warp Knit may be used.

When two or more UD prepregs are laminated to form a prepreg layer, it is preferable to laminate the reinforcing fibers of the two adjacent UD prepregs so that the fiber directions are orthogonal to each other from the viewpoint of excellent mechanical properties.
It is preferable to use a cross prepreg rather than a UD prepreg in that the prepreg laminating work is easy and the molded product can be made lighter.

Examples of the reinforcing fiber contained in the prepreg include carbon fiber, glass fiber, aramid fiber, high-strength polyester fiber, boron fiber, alumina fiber, silicon nitride fiber, nylon fiber and the like. Among these, carbon fiber is preferable because it is excellent in specific strength and specific elasticity.

Examples of the resin composition contained in the prepreg include a resin composition containing an epoxy resin, an unsaturated polyester resin, an acrylic resin, a vinyl ester resin, a phenol resin, a benzoxazine resin and the like. Among these, a resin composition containing an epoxy resin is preferable from the viewpoint that the strength after curing can be increased.

The SMC layer is a layer formed of SMC containing reinforcing fibers and a resin composition. The SMC layer may be a single layer composed of one SMC, or may be a plurality of layers composed of two or more SMCs.

The reinforcing fibers contained in SMC are short fibers obtained by cutting continuous fibers to a predetermined fiber length. The resin composition is impregnated into the sheet-shaped fiber base material formed by dispersing a plurality of short fibers to form a sheet-shaped SMC.

Examples of the reinforcing fiber contained in SMC include the same as those mentioned as the reinforcing fiber contained in the prepreg, and carbon fiber is preferable.
The fiber length of the short fibers contained in SMC is preferably 1.0 to 76.1 mm, more preferably 12.7 to 25.4 mm.

Examples of the resin composition contained in SMC include the same as those mentioned as the reinforcing fibers contained in the prepreg, and a resin composition containing a vinyl ester resin is preferable from the viewpoint of excellent shape followability in molding.

In the present invention, a composite laminate in which a prepreg layer is laminated on the first surface side and the second surface side of the SMC layer is used for molding. By using the composite laminate, the difference in the resin composition between the SMC layer and the prepreg layer on the first surface side and the second surface side of the SMC layer, and the variation in the length and orientation of the fibers are affected. Since they are offset in the thickness direction, the warp of the obtained molded product is suppressed.

In the present invention, the prepreg layer is arranged in a frame shape along the outer peripheral end portion of the SMC layer on both the first surface side and the second surface side of the SMC layer from the viewpoint of easily suppressing the warp of the molded product. It is preferable to form a composite laminate.
A prepreg layer having the same shape as the SMC layer may be laminated on the first surface side and the second surface side of the SMC layer so as to cover the entire surface of the SMC layer.

1 and 2 show an example of the composite laminate. It should be noted that the dimensions and the like of the figures exemplified in the following description are examples, and the present invention is not necessarily limited to them, and the present invention can be appropriately modified without changing the gist thereof. ..

As shown in FIGS. 1 and 2, the composite laminate 10 is formed on the first surface 12a side and the second surface 12b side of the rectangular SMC layer 12 in a plan view, and on the outer peripheral end portion of the SMC layer 12, respectively. A rectangular frame-shaped first prepreg layer 14 and a second prepreg layer 16 are laminated along the line.
The SMC layer 12 is a single layer composed of one SMC 13. The first prepreg layer 14 is a single layer composed of one frame-shaped prepreg 15. The second prepreg layer 16 is a single layer composed of one frame-shaped prepreg 17.

The composite laminate may be the composite laminate 10A exemplified in FIG. The same parts as those in FIG. 2 in FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted.
The composite laminated body 10A has a rectangular frame-shaped first surface on the first surface 12a side and the second surface 12b side of the rectangular SMC layer 12 in a plan view, respectively, along the outer peripheral end portion of the SMC layer 12. The prepreg layer 14A and the second prepreg layer 16A are laminated.
The first prepreg layer 14A is a multi-layer composed of two frame-shaped prepregs 15 and 15. The second prepreg layer 16A is a multi-layer composed of two frame-shaped prepregs 17 and 17.

As a method of arranging the prepreg layer in a frame shape along the outer peripheral end portion of the SMC layer, a method of cutting so as to hollow out the central portion of the prepreg to produce a frame-shaped prepreg and laminating is preferable.
If it is a cross prepreg, even if it is cut so as to hollow out the central portion, the reinforcing fibers are entangled over the entire frame-shaped prepreg layer, so that high strength can be easily obtained. When the central portion of the UD prepreg is cut to form a frame shape, it is preferable to stack two or more UD prepregs so that the fiber directions are orthogonal to each other and cut the central portion.

For example, when the prepreg layer is arranged in a frame shape along the outer peripheral end of the rectangular SMC layer in a plan view, the four strip-shaped prepregs are arranged along the outer peripheral end of each side of the SMC layer. It may be arranged to form a frame-shaped prepreg layer.

In the present invention, it is preferable that the prepreg layer on the first surface side and the second surface side of the SMC layer have a symmetrical configuration in the thickness direction of the composite laminate from the viewpoint of having a high effect of suppressing warpage. ..
Examples of the laminated structure symmetrical in the thickness direction include the following structures.
The prepreg layer is arranged in a frame shape on both the first surface side and the second surface side of the SMC layer. A cross prepreg is laminated on both the first surface side and the second surface side of the SMC layer to form a prepreg layer. A UD prepreg is laminated on both the first surface side and the second surface side of the SMC layer to form a prepreg layer. The same number of prepregs are laminated on the first surface side and the second surface side of the SMC layer to form a prepreg layer.

Further, when a plurality of UD prepregs are laminated on each of the first surface side and the second surface side of the SMC layer so that the fiber directions are orthogonal to each other, the fibers of each UD prepreg are laminated in the thickness direction of the composite laminate. An example is a configuration in which layers are laminated so that the directions are symmetrical. For example, UD prepreg (0 °), UD prepreg (90 °), SMC, UD prepreg (90 °), and UD prepreg (0 °) are laminated in this order (however, the fibers in parentheses are reinforcing fibers in a plan view). It means the angle of direction.)

When the prepreg layer is arranged in a frame shape on each of the first surface side and the second surface side of the SMC layer, it is preferable that the frame width of the frame-shaped prepreg layer is the same and is 10 mm or more. For example, in the composite laminate 10, it is preferable that the frame width D1 of the first prepreg layer 14 and the frame width D2 of the second prepreg layer 16 are the same and 10 mm or more. As a result, the effect of suppressing warpage becomes higher.

The frame width of the frame-shaped prepreg layer is preferably 10 mm or more, more preferably 10 mm or more and 300 mm or less, and further preferably 20 mm or more and 100 mm or less, although it depends on the size of the SMC layer. When the frame width is equal to or more than the lower limit of the above range, the effect of suppressing warpage becomes higher. When the frame width is equal to or less than the upper limit of the above range, the degree of freedom of the shape is increased.

The ratio of the area occupied by the prepreg layer laminated on the first surface side of the SMC layer to the area of the first surface of the SMC layer is defined as _Q1 (%). The ratio of the area occupied by the prepreg layer laminated on the second surface side of the SMC layer to the area of the second surface of the SMC layer is defined as the ratio _Q2 (%).
In the present invention, the ratio _Q1 and the ratio _Q2 are preferably the same and 10% or more from the viewpoint of increasing the effect of suppressing warpage.

The ratio Q ₁ is preferably 10% or more, more preferably 12% or more and 100% or less, and further preferably 25% or more and 50% or less. The upper limit of the ratio _Q1 is 100%. When the ratio Q ₁ is 100%, it means that the prepreg layer is laminated on the first surface side of the SMC layer so as to cover the entire first surface of the SMC layer.
When the ratio Q ₁ is equal to or higher than the lower limit of the above range, the effect of suppressing warpage is higher. When the ratio Q ₁ is equal to or less than the upper limit of the above range, the degree of freedom of the shape is increased.
The preferred range of proportion _Q2 is the same as the preferred range of proportion _Q1 .

As a method for molding the composite laminate, a method of compression molding with a molding die is preferable.
For example, the composite laminate is placed in a molding die provided with a pair of dies that form a cavity having a shape complementary to the shape of the desired molded product, and heated and pressed at a predetermined temperature and pressure using a press machine. Examples thereof include a method of curing the resin composition to obtain a molded product.

In compression molding, it is preferable to control the temperature of the molding die to a predetermined temperature and take out the molded product at that temperature after molding. As a result, it is not necessary to raise and lower the temperature of the molding die, and the molding cycle can be increased, so that the productivity can be increased.
The molding temperature can be appropriately set depending on the resin composition used for SMC and the prepreg, and is, for example, 130 to 150 ° C.
The set pressure at the time of molding can be appropriately set and is, for example, 3 to 12 MPa.

In the present invention, the composite laminate may be preformed into a shape close to the shape of the target molded product to form a preform before compression molding (main molding) by a molding die.
The method of preforming is not particularly limited.

The shapes of the preform and the fiber-reinforced molded product produced by the present invention are not particularly limited. The shape of a curved surface (including a combination of a plurality of planes) that cannot be expanded in a plane so that each layer is subjected to shear deformation during molding, that is, a three-dimensional curved surface shape may be used, and the plane can be expanded obtained by molding without shear deformation. It may have a curved surface shape.

As described above, when a molded product is obtained by compression molding, the molded product may be warped. This is because there are variations in fiber length and fiber orientation of the reinforcing fibers with the SMC prepreg, and uneven shrinkage occurs due to the difference in apparent heat shrinkage during heat curing during molding and subsequent cooling. This is because it easily occurs, so that thermal strain occurs inside the molded product and the molded product is partially deformed.

On the other hand, in the method for producing a fiber-reinforced composite material molded product of the present invention, a prepreg layer is formed on both the first surface side and the second surface side of the SMC layer. As a result, in the thickness direction of the molded product, the thermal strain is canceled out on the first surface side and the second surface side of the SMC layer, so that the occurrence of warpage is suppressed.
In the present invention, even when the types of the resin composition of SMC and the resin composition of prepreg are different, the warp of the molded product is sufficiently suppressed. The present invention is particularly effective in that a molded product having a three-dimensional shape including a convex shape can be manufactured with high dimensional accuracy.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to the following description.
(material)
The prepreg and SMC used in this example are shown below.
Prepreg (A-1): A sheet-shaped cross prepreg (manufactured by Mitsubishi Chemical Corporation, product name: TR3110 360 GMP) in which an epoxy resin composition is impregnated into a cloth material woven so that carbon fibers are orthogonal to each other.
Prepreg (A-2): A sheet-shaped cross prepreg (manufactured by Mitsubishi Chemical Corporation, product name: TR3110 368GMP) in which an epoxy resin composition is impregnated into a cloth material woven so that carbon fibers are orthogonal to each other.
Prepreg (A-3): A sheet-shaped UD prepreg (manufactured by Mitsubishi Chemical Corporation, product name: TR361E250S) in which carbon fibers are aligned in one direction and impregnated with an epoxy resin composition.
Prepreg (A-4): A sheet-shaped UD prepreg (manufactured by Mitsubishi Chemical Corporation, product name: TR368E250S) in which carbon fibers are aligned in one direction and impregnated with an epoxy resin composition.

SMC (B-1): Sheet-shaped SMC (manufactured by Mitsubishi Chemical Co., Ltd., product name: STR120N131-KA6N) in which a reinforcing fiber base material in which short carbon fibers are randomly dispersed is impregnated with a vinyl ester resin composition. ..
SMC (B-2): Sheet-shaped SMC (manufactured by Mitsubishi Chemical Co., Ltd., product name: STR101J129-KA6X) in which a reinforcing fiber base material in which short carbon fibers are randomly dispersed is impregnated with a vinyl ester resin composition. ..

(Example 1)
A composite laminate was obtained by the following steps 1 to 3.
Step 1: The prepreg (A-1) is cut into a square shape of 300 mm × 300 mm square, and the central portion thereof is cut into a 280 mm × 280 mm square, and the frame width is 10 mm as shown in FIG. A rectangular frame-shaped prepreg (C-1) (prepreg 20) was used. A total of two frame-shaped prepregs (C-1) were prepared by the same procedure.
Step 2: The SMC (B-1) was cut into 300 mm × 300 mm squares to form a square SMC (D-1).
Step 3: A frame-shaped prepreg (C) along the outer peripheral end of the SMC (D-1) on each of the first surface side and the second surface side of the SMC (D-1) in the thickness direction. -1) was laminated one by one to form a composite laminate having a three-layer structure. The four sides of the outer edge of each frame-shaped prepreg (C-1) were aligned with the four sides of the outer edge of the SMC (D-1).

A compression molding die having a pair of molds for forming a cavity having a shape complementary to a flat plate-shaped molded product having a length of 300 mm, a width of 300 mm, and a thickness of 2 mm was prepared. A mold for compression molding is heated to 140 ° C., a composite laminate is put into the mold, the mold is fastened, and a flat plate-shaped fiber-reinforced composite material molded product is held for 5 minutes by pressing and pressing at a set pressure of 4 MPa. Got

(Example 2)
In step 1, a rectangular frame having a frame width of 20 mm is the same as in step 1 of Example 1, except that the central portion of a 300 mm × 300 mm square prepreg is cut into a 260 mm × 260 mm square. Two prepregs (C-2) were prepared.
A three-layer composite laminate was produced in the same manner as in Example 1 except that the frame-shaped prepreg (C-2) was used instead of the frame-shaped prepreg (C-1), and a flat plate-shaped fiber-reinforced composite was prepared. A material molded product was obtained.

(Example 3)
In step 1, a rectangular frame having a frame width of 75 mm is the same as in step 1 of Example 1, except that the central portion of a 300 mm × 300 mm square prepreg is cut into a 150 mm × 150 mm square. Two prepregs (C-3) were prepared.
A three-layer composite laminate was produced in the same manner as in Example 1 except that the frame-shaped prepreg (C-3) was used instead of the frame-shaped prepreg (C-1), and a flat plate-shaped fiber-reinforced composite was prepared. A material molded product was obtained.

(Example 4)
In step 1, a rectangular frame width of 112.5 mm is obtained in the same manner as in step 1 of Example 1 except that the central portion of a 300 mm × 300 mm square prepreg is cut into a 75 mm × 75 mm square. Two frame-shaped prepregs (C-4) were prepared.
A three-layer composite laminate was produced in the same manner as in Example 1 except that the frame-shaped prepreg (C-4) was used instead of the frame-shaped prepreg (C-1), and a flat plate-shaped fiber-reinforced composite was prepared. A material molded product was obtained.

(Example 5)
In step 1, the prepreg (A-1) was cut into a square shape of 300 mm × 300 mm square, and then the central portion was not cut to obtain a square prepreg (C-5).
A three-layer composite laminate was produced in the same manner as in Example 1 except that a frame-shaped prepreg (C-5) was used instead of the frame-shaped prepreg (C-1), and a flat plate-shaped fiber-reinforced composite was prepared. A material molded product was obtained.

(Example 6)
In step 1, four frame-shaped prepregs (C-1) were prepared, and in step 3, two prepregs (C-1) were prepared on the first surface side and the second surface side of the SMC (D-1). In the same manner as in Example 1, a composite laminate having a five-layer structure was produced except for laminating, and a flat plate-shaped fiber-reinforced composite material molded product was obtained.

(Example 7)
A composite laminate having a three-layer structure was produced in the same manner as in Example 1 except that SMC (B-2) was used instead of SMC (B-1) in step 2, and a flat plate-shaped fiber-reinforced composite material molded product was produced. Got

(Example 8)
A three-layer composite laminate was produced in the same manner as in Example 1 except that the prepreg (A-2) was used instead of the prepreg (A-1) in step 1, and a flat plate-shaped fiber-reinforced composite material molded product was produced. Got

(Example 9)
Same as in Example 1 except that the prepreg (A-2) is used instead of the prepreg (A-1) in the procedure 1 and the SMC (B-2) is used instead of the SMC (B-1) in the procedure 2. A three-layer composite laminate was produced, and a flat plate-shaped fiber-reinforced composite material molded product was obtained.

(Example 10)
In step 1, the prepreg (A-3) is used instead of the prepreg (A-1), and in step 3, the fiber direction is set on each of the first surface side and the second surface side of the SMC (D-1). A five-layer composite laminate was produced in the same manner as in Example 1 except that two frame-shaped prepregs were laminated so as to be orthogonal to each other, and a flat plate-shaped fiber-reinforced composite material molded product was obtained.

(Example 11)
A five-layer composite laminate was produced in the same manner as in Example 10 except that SMC (B-2) was used instead of SMC (B-1) in step 2, and a flat plate-shaped fiber-reinforced composite material molded product was produced. Got

(Example 12)
A five-layer composite laminate was produced in the same manner as in Example 10 except that the prepreg (A-4) was used instead of the prepreg (A-3) in step 1, and a flat plate-shaped fiber-reinforced composite material molded product was produced. Got

(Example 13)
Same as in Example 10 except that the prepreg (A-4) is used instead of the prepreg (A-3) in the procedure 1 and the SMC (B-2) is used instead of the SMC (B-1) in the procedure 2. A five-layer composite laminate was produced to obtain a flat plate-shaped fiber-reinforced composite material molded product.

(Comparative Example 1)
As shown in FIG. 5, a composite laminate having the same configuration as the composite laminate 200 in which the prepreg 15 is laminated only on the first surface 12a side of the SMC layer 12 to form the first prepreg layer 14 is produced. , Used for molding.
Specifically, Example 1 except that in step 3, a frame-shaped prepreg (C-1) is laminated only on the first surface side of the SMC (D-1) to form a two-layer composite laminate. In the same manner as above, a flat plate-shaped fiber-reinforced composite material molded product was obtained.

(Comparative Example 2)
A two-layer composite laminate was produced in the same manner as in Comparative Example 1 except that SMC (B-2) was used instead of SMC (B-1) in step 2, and a flat plate-shaped fiber-reinforced composite material molded product was produced. Got

(Comparative Example 3)
A two-layer composite laminate was produced in the same manner as in Comparative Example 1 except that the prepreg (A-2) was used instead of the prepreg (A-1) in step 1, and a flat plate-shaped fiber-reinforced composite material molded product was produced. Got

(Comparative Example 4)
Same as in Comparative Example 1 except that the prepreg (A-2) is used instead of the prepreg (A-1) in the procedure 1 and the SMC (B-2) is used instead of the SMC (B-1) in the procedure 2. A two-layer composite laminate was produced, and a flat plate-shaped fiber-reinforced composite material molded product was obtained.

(Comparative Example 5)
In step 1, a prepreg (A-3) is used instead of the prepreg (A-1), and in step 3, two sheets are used so that the fiber directions are orthogonal to each other only on the first surface side of the SMC (D-1). A composite laminate having a three-layer structure was produced in the same manner as in Example 1 except that the frame-shaped prepregs were laminated, and a flat plate-shaped fiber-reinforced composite material molded product was obtained.

(Comparative Example 6)
A composite laminate having a three-layer structure was produced in the same manner as in Comparative Example 5, except that SMC (B-2) was used instead of SMC (B-1) in step 2, and a flat plate-shaped fiber-reinforced composite material molded product was produced. Got

(Comparative Example 7)
A three-layer composite laminate was produced in the same manner as in Comparative Example 5, except that the prepreg (A-4) was used instead of the prepreg (A-3) in step 1, and a flat plate-shaped fiber-reinforced composite material molded product was produced. Got

(Comparative Example 8)
Same as in Comparative Example 5 except that the prepreg (A-4) is used instead of the prepreg (A-3) in the procedure 1 and the SMC (B-2) is used instead of the SMC (B-1) in the procedure 2. A five-layer composite laminate was produced to obtain a flat plate-shaped fiber-reinforced composite material molded product.

(Warp evaluation)
With the flat plate-shaped fiber-reinforced composite material molded product obtained in each example placed on the surface plate, the distance d from the surface of the surface plate to the measurement point on the upper surface of the fiber-reinforced composite material molded product was measured. As shown in FIG. 6, the number and positions of the measurement points a are 5 points at intervals of 70 mm from the position of 10 mm from the outer edge in the vertical direction and intervals of 70 mm from the position of 10 mm from the outer edge in the horizontal direction in the plan view of the molded product 100. The total of 5 points was 25 points.
Of the 25 measurement points, the distance d measured at the center measurement point is defined as the reference distance d _S , and the distance d measured at the other 24 measurement points is the absolute value of the difference from the reference distance d _S (| dd _S |) was calculated, and the value obtained by adding the maximum value and the minimum value was defined as the warp (mm) and evaluated according to the following criteria.
<Evaluation criteria>
◯ (good): The warp is less than 2.5 mm.
X (defective): The warp is 2.5 mm or more.

Table 1 shows the composition of the composite laminate of each example and the evaluation result of the warp of the fiber-reinforced composite material molded product.
In addition, "PP / SMC / PP" in the column of the laminated structure in Table 1 means that the prepreg, the SMC, and the prepreg are laminated in this order, and the same applies to other notations. Further, the numerical value in parentheses in the column of the laminated structure means the angle in the fiber direction of the carbon fiber of the UD prepreg.

As shown in Table 1, in Examples 1 to 13 in which the composite laminate in which the prepreg layer is laminated on the first surface side and the second surface side of the SMC layer is formed, only the first surface side of the SMC layer is formed. Warpage was suppressed as compared with Comparative Examples 1 to 8 in which the prepreg layers were laminated, and the dimensional accuracy was high.

10, 10A ... composite laminate, 12 ... SMC layer, 12a ... first surface, 12b ... second surface, 14 ... first prepreg layer, 15 ... frame-shaped prepreg, 16 ... second prepreg layer, 17 ... Frame-shaped prepreg.

Claims (4)

A second prepreg layer is laminated on a part of the first surface of the sheet molding compound layer having the first surface and the second surface facing opposite to each other in the thickness direction. A second prepreg layer is laminated on a part of the surface to form a composite laminate, and then a molded product is obtained from the composite laminate by a compression molding method.
The first prepreg layer and the second prepreg layer are arranged in a frame shape along the outer peripheral end of the sheet molding compound layer to form the composite laminate.
The first prepreg layer and the second prepreg layer consist of one or more prepregs selected from UD prepregs and prepregs based on reinforced fiber fabrics.
A method for manufacturing a fiber-reinforced composite material molded product, wherein the first prepreg layer and the second prepreg layer are symmetrically configured in the thickness direction of the composite laminate. The method for producing a fiber-reinforced composite material molded product according to claim 1 , wherein the frame width of the first prepreg layer and the frame width of the second prepreg layer are 10 mm or more. Ratio of the area of the first prepreg layer to the area of the first surface of the sheet molding compound layer _Q1 and the ratio of the area of the second prepreg layer to the area of the second surface of the sheet molding compound layer. The method for producing a fiber-reinforced composite material molded product according to claim 1 or 2 _, wherein Q2 is 10% or more. The ratio Q ₁ And the above ratio Q ₂ However, the method for producing a fiber-reinforced composite material molded product according to claim 3, wherein the content is 50% or less.

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