Method of manufacturing composite molding

Abstract

To provide a method capable of manufacturing a composite molding having high bonding strength and high positional accuracy, and having improved productivity.SOLUTION: Provided is a method of manufacturing a composite molding by integrating a fiber-reinforced thermoplastic resin sheet (A) made of reinforcing fibers and a thermoplastic resin, and a thermoplastic resin composition (B) in a mold. The mold is configured so that at least a portion of its cavity forming surface can move in a direction approaching to and separating from a product surface of the composite molding. The method has: a first step of placing the fiber-reinforced thermoplastic resin sheet (A) on the cavity forming surface at an offset position separated away from the product surface; a second step of starting injecting the molten thermoplastic resin composition (B) into a cavity of the mold; and a third step of bringing the offset cavity forming surface close to the product surface and integrating the fiber-reinforced thermoplastic resin sheet (A) placed on the cavity forming surface with the thermoplastic resin composition (B) by welding.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a composite molded body, and in particular to a method for producing a composite molded body that can weld a fiber-reinforced thermoplastic resin sheet consisting of reinforcing fibers and a thermoplastic resin to a thermoplastic resin composition in a complex three-dimensional shape with a high degree of precision. [Background technology]

[0002] There are various known methods for manufacturing composite molded articles that integrate a fiber-reinforced thermoplastic resin (FRTP) substrate with another thermoplastic resin molded article. When manufacturing a composite molded article with a complex shape, a common method is to pre-shape the FRTP substrate into a three-dimensional shape, insert it into an injection molding die, and then inject resin to obtain the composite molded article. However, this method requires a pre-shaping step, which makes the molding process complicated.

[0003] In response to this, for example, Patent Document 1 discloses a method for manufacturing a composite molded product in which two sheet-like insert materials are supplied into a mold and fixed with movable pins, molding resin is supplied between the two insert materials, and then the insert materials are compressed and integrated in the mold. Patent Document 2 discloses an injection insert molding method characterized by inserting an FRP base material containing continuous reinforcing fibers and thermoplastic resin A through a slit in the mold and aligning it with the mold cavity, and then injecting and filling thermoplastic resin B into the mold to form a molded product.

[0004] Patent Document 3 discloses a method for manufacturing a composite molded product, which is characterized by supplying three or more composite sheets into a mold, holding each sheet with a holding pin, supplying molding material between the composite sheets to integrate them, and imparting a bending angle to the composite sheets. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-130854 [Patent Document 2] WO2017115650 publication [Patent Document 3] Japanese Patent Application Publication No. 2019-104138 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the invention described in Patent Document 1, when fixing an insert in a mold, it is necessary to drill a hole in part of the insert, making it difficult to make the entire surface an insert surface. In Patent Document 2, the mold is closed, and an FRP base material is inserted into the cavity through a slit and fixed, but it is difficult to limit the area to which the base material is applied and to arrange the FRP base material on both sides. In Patent Document 3, multiple FRP base materials are supplied to a mold and each base material is fixed with a holding pin, but it is difficult to integrate them with precision.

[0007] Therefore, the object of the present invention is to address the problems in the conventional technology as described above, and to provide a method for producing a composite molded body that has high bonding strength and high positional accuracy as well as improved productivity, by offsetting the mold for the fiber-reinforced thermoplastic resin sheet application portion from the product surface, thereby enabling integration with the injected thermoplastic resin composition. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention employs the following configuration. (1) A method for producing a composite molded body by integrating a fiber-reinforced thermoplastic resin sheet (A) consisting of reinforcing fibers and a thermoplastic resin with a thermoplastic resin composition (B) in a mold, wherein the mold is configured so that at least a part of its cavity-forming surface can move in a direction approaching or moving away from the product surface of the composite molded body, and the method comprises: a first step of arranging the fiber-reinforced thermoplastic resin sheet (A) on the cavity-forming surface at an offset position away from the product surface; a second step of starting to inject the molten thermoplastic resin composition (B) into the cavity of the mold; and a third step of bringing the offset cavity-forming surface close to the product surface and integrating the fiber-reinforced thermoplastic resin sheet (A) arranged on the cavity-forming surface with the thermoplastic resin composition (B) by welding. (2) The method for producing a composite molding according to (1), wherein the reinforcing fibers are continuous fibers oriented in one direction. (3) The method for producing a composite molded body according to (1) or (2), wherein the attachment surface of the fiber-reinforced thermoplastic resin sheet (A) in the composite molded body has a curved surface; (4) The method for producing a composite molded body according to any one of (1) to (3), wherein the fiber-reinforced thermoplastic resin sheet (A) is shaped into a three-dimensional shape in a mold and integrated with the thermoplastic resin composition (B); (5) The method for producing a composite molded product according to any one of (1) to (4), wherein the fiber-reinforced thermoplastic resin sheet (A) has a cut. (6) The method for producing a composite molded product according to any one of (1) to (5), wherein the fiber-reinforced thermoplastic resin sheet (A) is made of a polyamide-based resin or a polyphenylene sulfide-based resin. (7) The method for producing a composite molded article according to any one of (1) to (6), wherein the thermoplastic resin composition (B) comprises a polyamide resin or a polyphenylene sulfide resin. (8) The method for producing a composite molded body according to any one of (1) to (7), wherein the reinforcing fibers include carbon fibers. (9) The method for producing a composite molded article according to any one of (1) to (8), wherein the thermoplastic resin composition (B) contains a thermoplastic resin and carbon fibers. (10) The method for producing a composite molded body according to any one of (1) to (9), wherein the offset length is 1 to 20 mm. (11) The method for producing a composite molded product according to any one of (1) to (10), wherein two of the fiber-reinforced thermoplastic resin sheets (A) are used and positioned opposite each other in a mold. [Effects of the Invention]

[0009] Thus, according to the method for producing a composite molded body of the present invention, in a method for producing a composite molded body by integrating a fiber-reinforced thermoplastic resin sheet (A) consisting of reinforcing fibers and a thermoplastic resin with a thermoplastic resin composition (B), the method includes a first step of placing the fiber-reinforced thermoplastic resin sheet (A) on the cavity-forming surface of a mold that is located in a position partially offset with respect to the product surface, a second step of injecting the molten thermoplastic resin composition (B) into the cavity, and a third step of advancing the partially offset cavity-forming surface of the mold to the product surface. This improves the positional accuracy of the bonding and integration of the fiber-reinforced thermoplastic resin sheet (A) in the composite molded body and prevents the thermoplastic resin composition (B) from seeping in, making it possible to obtain a composite molded body that combines excellent mechanical properties and moldability. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram showing a method for producing a composite molded body according to one embodiment of the present invention. [Figure 2] 1 is a schematic diagram showing an example of a thermoplastic resin molded article having a complex three-dimensional shape. [Figure 3] FIG. 2 is a schematic diagram showing an example of a composite molded body. [Figure 4] FIG. 1 is a schematic perspective view showing an example of a continuous fiber reinforced thermoplastic resin sheet having incisions. [Figure 5] FIG. 10 is a schematic diagram showing a stiffness test of a composite molding. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described in detail below with reference to embodiments. The method for producing a composite molded body of the present invention is a method for producing a composite molded body by integrating a fiber-reinforced thermoplastic resin sheet (A) consisting of reinforcing fibers and a thermoplastic resin with a thermoplastic resin composition (B), and includes a first step of placing the fiber-reinforced thermoplastic resin sheet (A) on the cavity-forming surface of a mold that is located in a position partially offset from the product surface, a second step of injecting the molten thermoplastic resin composition (B), and a third step of bringing the partially offset cavity-forming surface of the mold closer to the product surface.

[0012] These steps will be specifically described with reference to FIG. 1, which shows a method for producing a composite molded body according to one embodiment of the present invention. (Step I) The mold (for example, mold (fixed side) 1 and mold (movable side) 2) is in an open state, and the cavity-forming surface 3a of the mold movable part 3 is in an offset position away from the product surface 4. (Step II) The cavity-forming surface 3a has a curved surface, and a fiber-reinforced thermoplastic resin sheet (A) 5 is placed thereon (first process). (Step III) After closing the molds 1 and 2, injection of the molten thermoplastic resin composition (B) 6 into the cavity 3b begins (second process). (Step IV) After the molten thermoplastic resin composition (B) 6 reaches the product surface 4, the cavity-forming surface 3a (more precisely, the fiber-reinforced thermoplastic resin sheet (A) 5 arranged on the cavity-forming surface 3a) at the offset position is brought closer to the product surface 4, whereby the fiber-reinforced thermoplastic resin sheet (A) 5 and the molten thermoplastic resin composition (B) 6 are joined together and pressed by the heat of the molten thermoplastic resin composition (B) and the resin pressure in the cavity 3b. The fiber-reinforced thermoplastic resin sheet (A) 5 is shaped to conform to the shape of the cavity-forming surface 3a while being welded and integrated with the thermoplastic resin composition (B) 6 (third step). (Step V) After cooling is complete, the mold movable parts 3 are separated from each other, and the cavity-forming surface 3a is separated to the offset position. (Step VI) This is a manufacturing method in which the molds 1 and 2 are opened, and the composite molded body 7 is removed. In this embodiment, a composite molded body 7 is produced in which fiber-reinforced thermoplastic resin sheets (A) 5 are integrated on both sides of the thermoplastic resin composition (B) 6.

[0013] The fiber-reinforced thermoplastic resin sheet (A) in the present invention is preferably a continuous fiber in which the reinforcing fibers are oriented in one direction. Such a unidirectional substrate can exhibit particularly high mechanical properties in the specific direction in which the continuous reinforcing fibers are arranged. For example, by integrating a substrate made of a tape-shaped continuous fiber-reinforced thermoplastic resin sheet (A) with a thermoplastic resin composition (B) with high precision at a desired predetermined position, the composite molded body as a whole can efficiently exhibit high mechanical properties in the desired specific direction. Moreover, since the substrate made of the reinforcing continuous fiber-reinforced thermoplastic resin sheet (A) is tape-shaped, it is possible to efficiently reinforce the composite molded body by focusing on the areas where reinforcement is required.

[0014] In the composite molded product of the present invention, the surface to which the fiber-reinforced thermoplastic resin sheet (A) is attached preferably has a curved surface. In this case, in the method for producing a composite molded product of the present invention, it is preferable that the injection molding die has an internal curved surface so that a composite molded product having a curved surface can be obtained. Here, the shape having a curved surface means, for example, as shown in FIG. 2, a shape in which the surface to be integrated with the fiber-reinforced thermoplastic resin sheet (A) in a thermoplastic resin molded product 8 made of the thermoplastic resin composition (B) in the composite molded product has a curved surface 9, for example, a shape having a curved surface 9 in the width direction.

[0015] The partially offset cavity-forming surface 3a of molds 1 and 2 as shown in Figure 1 is preferably flat or has a complex three-dimensional shape, and a fiber-reinforced thermoplastic resin sheet (A) is placed at the offset position. Next, a molten thermoplastic resin composition (B) is injected into the cavity 3b, and then the partially offset cavity-forming surface 3a of the mold is advanced to the product surface 4, and by using the heat and pressure of the thermoplastic resin composition (B), the fiber-reinforced thermoplastic resin sheet (A) 5 is shaped into a complex three-dimensional shape, and the injected thermoplastic resin composition (B) 6 is molded into a thermoplastic resin molded product 8 and welded to the fiber-reinforced thermoplastic resin sheet (A) 5, resulting in an integrated composite molded product 7 as shown in Figure 3.

[0016] The fiber-reinforced thermoplastic resin sheet (A) of the present invention preferably has incisions 10 as shown in Fig. 4. By having incisions, the fiber-reinforced thermoplastic resin sheet (A) can be molded into a complex three-dimensional shape without problems such as damage or wrinkles in the sheet or breakage of the carbon fibers, and a composite molded product 7 can be obtained that is excellent not only in rigidity and strength but also in appearance and durability.

[0017] The incisions in the fiber-reinforced thermoplastic resin sheet (A) of the present invention are preferably provided in the orientation direction of the continuous fibers and / or in a direction crossing the continuous fibers, and more preferably in the orientation direction of the continuous fibers. By providing incisions in the orientation direction of the continuous fibers, the fiber-reinforced thermoplastic resin sheet (A) can be accurately shaped into a complex three-dimensional shape having a curved surface, and a composite molded product 7 can be obtained that is free from sheet breakage and wrinkles and has excellent rigidity, strength, appearance, and durability.

[0018] The length of the cuts in the fiber-reinforced thermoplastic resin sheet (A) of the present invention is preferably 1 mm or more and 50 mm or less, in order to provide excellent accuracy in shaping into shapes with curved surfaces or complex shapes and to prevent sheets from overlapping each other.

[0019] The fiber-reinforced thermoplastic resin sheet (A) in the present invention can be obtained by making incisions using a laser marker, a cutting plotter, a cutting die, etc. If the incisions are made using a laser marker, it is preferable because it has the effect of being able to process complex incisions such as curves and zigzag lines at high speed, and if the incisions are made using a cutting die, it has the effect of being able to process at high speed.

[0020] In the fiber-reinforced thermoplastic resin sheet (A) of the present invention, the length (average fiber length) La of the cut reinforcing fibers is not particularly limited, but when the incisions are made in the direction crossing the continuous fibers, it is preferably 5 mm or more and 100 mm or less from the viewpoint of mechanical properties and formability. When the incisions are made in the orientation direction of the continuous fibers, it is preferable that the sheet length and the reinforcing fiber length La are the same length from the viewpoint of excellent rigidity and strength of the composite molded body.

[0021] The incisions in the fiber-reinforced thermoplastic resin sheet (A) of the present invention may penetrate the thickness direction of the sheet, or may be provided from each of the upper and lower surfaces of the continuous fiber-reinforced thermoplastic resin sheet without penetrating the thickness direction. It is preferable that the incisions penetrate the thickness direction of the continuous fiber-reinforced thermoplastic resin sheet in order to improve the formability of the continuous fiber-reinforced thermoplastic resin sheet and to suppress the occurrence of wrinkles in the continuous fiber-reinforced thermoplastic resin sheet and breakage of the carbon fibers.

[0022] In the present invention, the method for measuring the incisions in the continuous fiber reinforced thermoplastic resin sheet is to take a photograph of the surface of the continuous fiber reinforced thermoplastic resin sheet having the incisions at 20 times magnification using a laser microscope to confirm the presence or absence of the incisions. The depth of the incisions in the thickness direction can be confirmed by observing the inside of the sheet in the thickness direction using an X-ray CT device.

[0023] The thermoplastic resin in the fiber-reinforced thermoplastic resin sheet (A) used in the present invention is preferably a polyamide resin or a polyphenylene sulfide resin. In this case, the continuous fiber-reinforced thermoplastic resin sheet and the thermoplastic resin molded body are well welded together, and a composite molded body excellent in rigidity, strength, and impact resistance can be obtained.

[0024] In the fiber-reinforced thermoplastic resin sheet (A) used in the present invention, examples of reinforcing fibers used for the unidirectionally oriented continuous fibers include carbon fiber, glass fiber, and aramid fiber, and it is preferable to use carbon fiber. When carbon fiber is used, not only can the rigidity and strength of the composite molded body be most efficiently improved, but the sheet thickness for obtaining the same performance can also be reduced, making it easier to obtain a composite molded body having a complex shape.

[0025] The thermoplastic resin composition (B) used in the present invention preferably contains a thermoplastic resin and carbon fiber. When carbon fiber is used, not only can the rigidity and strength of the composite molded article be most efficiently improved, but also the weight of the composite molded article can be reduced to obtain the same performance.

[0026] Examples of the thermoplastic resin in the thermoplastic resin composition (B) used in the present invention include polyamide resins (such as polyamide 6 and polyamide 66), polyester resins (such as polyethylene terephthalate, polybutylene terephthalate, and polycarbonate), polyphenylene ether, polyphenylene sulfide resin, polyoxymethylene (such as polyacetal), acrylonitrile-butadiene-styrene copolymer, polystyrene, liquid crystal polyester, and polypropylene. Polyamide resins and polyphenylene sulfide resins are preferred. By using polyamide resins and polyphenylene sulfide resins, composite molded articles with excellent moldability and mechanical properties can be obtained.

[0027] In addition, it is preferable that the thermoplastic resin in the fiber-reinforced thermoplastic resin sheet (A) and the thermoplastic resin in the thermoplastic resin composition (B) used in the present invention are both polyamide-based resins or polyphenylene sulfide-based resins. In this case, the fiber-reinforced thermoplastic resin sheet (A) and the thermoplastic resin composition (B) are well welded together, and a composite molded product excellent in rigidity, strength, and impact resistance can be obtained.

[0028] The thermoplastic resin composition (B) used in the present invention may contain fillers other than carbon fiber, mold release agents, stabilizers, ultraviolet absorbers, flame retardants, flame retardant assistants, anti-dripping agents, lubricants, other thermoplastic resins, and thermosetting resins, as long as the effects of the invention are not impaired.

[0029] In the present invention, the offset length is preferably in the range of 1 to 20 mm, more preferably 2 mm or more, and more preferably 10 mm or less. Here, the offset length refers to the length (linear distance) between the position when the fiber-reinforced thermoplastic resin sheet (A) is placed in the first step and the position of the product surface after it is brought close to the product surface in the third step.

[0030] If the offset length is less than 1 mm, the fiber-reinforced thermoplastic resin sheet (A) may move during injection, making it difficult to precisely weld the fiber-reinforced thermoplastic resin sheet (A). If the offset length exceeds 20 mm, the resulting composite molded product may have a different shape due to differences in thickness, etc., burrs may be generated from the mold, and conversely, the weldability between the thermoplastic resin composition (B) and the fiber-reinforced thermoplastic resin sheet (A) may be reduced.

[0031] The fiber-reinforced thermoplastic resin sheets (A) used in the present invention are preferably arranged in opposing positions within a mold, as shown in Figure 1. When the fiber-reinforced thermoplastic resin sheet (A) is arranged on one side of the mold and molded, the difference in shrinkage between the fiber-reinforced thermoplastic resin sheet (A) and the thermoplastic resin composition (B) causes significant warping of the composite molded body and unstable dimensional accuracy. However, when the fiber-reinforced thermoplastic resin sheets (A) are arranged on both sides and molded, no warping occurs, dimensional accuracy is stable, and high mechanical properties can be exhibited. [Example]

[0032] The present invention will be described below based on examples, but the present invention is not limited to these examples.

[0033] Example 1 A fiber-reinforced thermoplastic resin sheet (A) (25 mm wide, 300 mm long, 0.2 mm thick, consisting of polyphenylene sulfide resin with a continuous fiber content of 50% by weight and carbon fiber) was placed on a cavity-forming surface offset by 10 mm in a mold having the shape shown in Figure 2. In an injection molding machine set at a cylinder temperature of 330°C and a mold temperature of 150°C, injection of 40% by weight glass fiber-reinforced polyphenylene sulfide resin as thermoplastic resin composition (B) into the mold cavity was started, and when the thermoplastic resin composition (B) reached the end of the thermoplastic resin sheet (A), the offset cavity-forming surface was brought closer to the product surface, while injection was continued.

[0034] As a result, a good molded product was obtained in which the fiber-reinforced thermoplastic resin sheet (A) did not deviate from its designated position in the composite molded body and the thermoplastic resin composition (B) did not wrap around to the front side of the fiber-reinforced thermoplastic resin sheet (A). In addition, a molded composite molded body in which the fiber-reinforced thermoplastic resin sheet (A) and the thermoplastic resin composition (B) were firmly welded together was obtained.

[0035] This molded product was used to conduct a test using a measuring device as shown in Fig. 5. Specifically, the molded product of composite molding 7 was fixed to a fixture 11 using fixing bolts 12, and a test was conducted in which a downward load P was applied to an indenter 13 to displace it at a constant speed. The amount of displacement before the start of the test at the time when a load of 10 N was applied was read as an index of rigidity, and the amount of displacement was found to be 15 mm.

[0036] Example 2 A fiber-reinforced thermoplastic resin sheet (A) (25 mm wide, 300 mm long, 0.2 mm thick, consisting of polyphenylene sulfide resin with a continuous fiber content of 50% by weight and carbon fiber) was cut with cuts as shown in Figure 4 (equally spaced 20 mm apart, with 5 mm spacing in the width direction and an alternating pattern), placed on the curved cavity-forming surface of a mold, and injection molded.

[0037] As a result, the fiber reinforced thermoplastic resin sheet (A) was able to be neatly shaped along the curved surface of the mold, resulting in a good molded product without wrinkles, and a molded composite product in which the fiber reinforced thermoplastic resin sheet (A) and the thermoplastic resin composition (B) were more firmly welded together was obtained. Subsequently, a test similar to that in Example 1 was performed, and the displacement was 14 mm.

[0038] Example 3 A fiber-reinforced thermoplastic resin sheet (A-2) (25 mm wide, 300 mm long, 0.3 mm thick, consisting of polyamide 6 resin with a continuous fiber content of 50% by weight and carbon fiber) was placed on a cavity-forming surface offset by 10 mm in a mold. In an injection molding machine set at a cylinder temperature of 280°C and a mold temperature of 120°C, injection of 45% by weight of glass fiber-reinforced polyamide 6 resin as thermoplastic resin composition (B) into the mold cavity was started, and when the thermoplastic resin composition (B) reached the end of the thermoplastic resin sheet (A), the offset cavity-forming surface was brought closer to the product surface, and injection was continued.

[0039] As a result, a good molded product was obtained in which the fiber-reinforced thermoplastic resin sheet (A) did not deviate from its designated position in the composite molded body and the thermoplastic resin composition (B) did not wrap around to the front side of the fiber-reinforced thermoplastic resin sheet (A). In addition, a molded composite molded body in which the fiber-reinforced thermoplastic resin sheet (A) and the thermoplastic resin composition (B) were firmly welded together was obtained.

[0040] Example 4 A fiber-reinforced thermoplastic resin sheet (A) (25 mm wide, 300 mm long, 0.2 mm thick, consisting of polyphenylene sulfide resin with a continuous fiber content of 50% by weight and carbon fiber) was placed on a cavity-forming surface offset by 10 mm in a mold having the shape shown in Figure 2. In an injection molding machine set at a cylinder temperature of 330°C and a mold temperature of 150°C, injection of 30% by weight carbon fiber-reinforced polyphenylene sulfide resin as thermoplastic resin composition (B) into the mold cavity was started, and when the thermoplastic resin composition (B) reached the end of the thermoplastic resin sheet (A), the offset cavity-forming surface was brought closer to the product surface, while injection was continued.

[0041] As a result, a good molded product was obtained in which the fiber-reinforced thermoplastic resin sheet (A) did not deviate from the predetermined position of the composite molded product, and the thermoplastic resin composition (B) did not wrap around to the front side of the fiber-reinforced thermoplastic resin sheet (A). In addition, a molded product of a composite molded product in which the fiber-reinforced thermoplastic resin sheet (A) and the thermoplastic resin composition (B) were firmly welded was obtained. Subsequently, a test similar to that in Example 1 was performed, and the displacement was 11 mm.

[0042] Example 5 A fiber-reinforced thermoplastic resin sheet (A) (25 mm wide, 300 mm long, 0.2 mm thick, consisting of polyphenylene sulfide resin with a continuous fiber content of 50% by weight and carbon fiber) was cut with cuts as shown in Figure 4 (equally spaced at 20 mm intervals, with 5 mm intervals in the width direction and an alternating pattern), placed on the curved cavity-forming surface of a mold, and injection of 30% by weight carbon fiber-reinforced polyphenylene sulfide resin as thermoplastic resin composition (B) into the mold cavity was initiated to perform injection molding.

[0043] As a result, the fiber-reinforced thermoplastic resin sheet (A) was able to be neatly shaped to fit the curved surface of the mold, resulting in a wrinkle-free molded product, and a composite molded product in which the fiber-reinforced thermoplastic resin sheet (A) and the thermoplastic resin composition (B) were more firmly welded together was obtained. Subsequently, a test similar to that in Example 1 was conducted, and the displacement was 9 mm.

[0044] (Comparative Example 1) In Example 1, the thermoplastic resin composition (B) was injected in the same manner as in Example 1, except that the fiber-reinforced thermoplastic resin sheet (A) was placed on a cavity-forming surface that was not offset in the mold. As a result, the fiber-reinforced thermoplastic resin sheet (A) placed on the cavity-forming surface significantly deviated from its predetermined position, and the thermoplastic resin composition (B) was wrapped around the surface of the fiber-reinforced thermoplastic resin sheet (A). It was also confirmed that the welding of the fiber-reinforced thermoplastic resin sheet (A) and the thermoplastic resin composition (B) was partially insufficient.

[0045] (Comparative Example 2) In Example 1, the thermoplastic resin composition (B) was injected without using the fiber-reinforced thermoplastic resin sheet (A). As a result of carrying out the same test as in Example 1, the displacement was 30 mm. [Industrial Applicability]

[0046] The method for producing a composite molded article according to the present invention can be applied to the production of any composite molded article in which a fiber-reinforced thermoplastic resin sheet is formed into a three-dimensional shape and integrated with a thermoplastic resin composition. In particular, by taking advantage of its excellent mechanical properties, the composite molded article can be used for various purposes such as aircraft parts, automobile parts, electrical and electronic parts, building materials, various containers, daily necessities, household goods, and sanitary products. [Explanation of symbols]

[0047] 1 Mold (fixed side) 2. Mold (movable side) 3 Movable parts of the mold 3a Cavity forming surface 3b cavity 4 Product side 5. Fiber-reinforced thermoplastic resin sheet (A) 6 Thermoplastic resin composition (B) 7 Composite molded body 8 Thermoplastic resin molding 9 Curved Surfaces 10 Cut 11 Fixture 12 Fixing bolt 13 Indenter

Claims

1. A method for producing a composite molded body by integrating a fiber-reinforced thermoplastic resin sheet (A) consisting of reinforcing fibers and a thermoplastic resin with a thermoplastic resin composition (B) in a mold, wherein the mold is configured so that at least a portion of its cavity-forming surface can move in a direction approaching or moving away from the product surface of the composite molded body, and the method for producing a composite molded body is characterized by comprising: a first step of placing the fiber-reinforced thermoplastic resin sheet (A) on the cavity-forming surface that is in an offset position away from the product surface; a second step of starting to inject the molten thermoplastic resin composition (B) into the cavity of the mold; and a third step of bringing the offset cavity-forming surface close to the product surface and integrating the fiber-reinforced thermoplastic resin sheet (A) placed on the cavity-forming surface with the thermoplastic resin composition (B) by welding.

2. 2. The method for producing a composite molding according to claim 1, wherein the reinforcing fibers are continuous fibers oriented in one direction.

3. The method for producing a composite molded body according to claim 1 or 2, wherein the attachment surface of the fiber-reinforced thermoplastic resin sheet (A) in the composite molded body has a curved surface.

4. The method for producing a composite molded product according to claim 1 or 2, wherein the fiber-reinforced thermoplastic resin sheet (A) is shaped into a three-dimensional shape in a mold and integrated with the thermoplastic resin composition (B).

5. The method for producing a composite molded body according to claim 1 or 2, wherein the fiber-reinforced thermoplastic resin sheet (A) has a notch.

6. The method for producing a composite molded body according to claim 1 or 2, wherein the fiber-reinforced thermoplastic resin sheet (A) is made of a polyamide-based resin or a polyphenylene sulfide-based resin.

7. 3. The method for producing a composite molded article according to claim 1, wherein the thermoplastic resin composition (B) comprises a polyamide resin or a polyphenylene sulfide resin.

8. The method for producing a composite molded article according to claim 1 or 2, wherein the reinforcing fibers include carbon fibers.

9. The method for producing a composite molded article according to claim 1 or 2, wherein the thermoplastic resin composition (B) contains a thermoplastic resin and carbon fibers.

10. The method for producing a composite molded product according to claim 1 or 2, wherein the offset length is 1 to 20 mm.

11. The method for producing a composite molded body according to claim 1 or 2, wherein two of the fiber-reinforced thermoplastic resin sheets (A) are used and arranged in opposing positions in a mold.

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