Manufacturing method of composite molding body

Abstract

To provide a manufacturing method that achieves excellent positional accuracy in laminating continuous fiber reinforced thermoplastic resin sheets and that achieves both mechanical properties and moldability in a composite molded body obtained by integrating a continuous fiber reinforced thermoplastic resin sheet (A) and a material (B) containing a thermoplastic resin composition.SOLUTION: A manufacturing method for a composite molded body comprises: placing a continuous fiber-reinforced thermoplastic resin sheet (A) (hereinafter referred to as a sheet (A)) containing continuous reinforcing fibers and a thermoplastic resin composition on the cavity surface of an injection molding die by suction; and then integrating the sheet with a material (B) containing a thermoplastic resin composition to produce a composite molded product.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a composite molded article. [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-shaped insert materials are supplied into a mold and fixed with movable pins, a molding resin is supplied between the two insert materials, and the two are then compressed and integrated in the mold. Patent Document 2 discloses an injection insert molding method in which three or more sheet-shaped composite materials are supplied into a mold, each sheet is held and separated with a holding pin, a molding thermoplastic resin is supplied between the multiple sheet-shaped composite materials to integrate them and impart a bending angle to the sheet-shaped composite materials. Patent Document 3 discloses a method for manufacturing a molded product in which a sheet-shaped insert member heated to a temperature higher than the cavity surface of the mold is held by a support member and a molding material is injected. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-130854 [Patent Document 2] Japanese Patent Application Publication No. 2019-104138 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-215463 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the invention described in Patent Document 1, when fixing an insert member in a mold with a movable pin, not only is it necessary to drill a hole in part of the insert member, but it is also considered difficult to fix it accurately. The method described in Patent Document 2 supplies multiple FRP substrates to a mold and fixes each substrate with a holding pin, but it is considered difficult to accurately integrate them with the thermoplastic resin used for molding. The method described in Patent Document 3 requires auxiliary equipment such as a support member and requires the insert member to be heated to a temperature higher than the cavity surface. Furthermore, when molding products with complex shapes, the resin constituting the injected molding material can get between the complex-shaped cavity surface and the insert member, which is known as resin creeping.

[0006] Therefore, the object of the present invention is to focus on the problems in the conventional technology as described above, and to provide a method for manufacturing a composite molded body that combines mechanical properties and moldability, while achieving high positional accuracy and welding strength, even when a composite molded body in which a continuous fiber-reinforced thermoplastic resin sheet and a material containing a thermoplastic resin composition are integrated is formed into a complex three-dimensional shape, without the thermoplastic resin constituting the material containing the thermoplastic resin composition from wrapping around. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention employs the following configuration. (1) A method for producing a composite molded body, comprising: placing a continuous fiber-reinforced thermoplastic resin sheet (A) (hereinafter referred to as sheet (A)) containing continuous reinforcing fibers and a thermoplastic resin composition on the cavity surface of an injection molding die by suction; and then integrating the sheet with a material (B) containing a thermoplastic resin composition to produce a composite molded body. (2) The method for producing a composite molded body according to (1), wherein an even number of sheets (A) are used, and two sheets are placed opposite each other on the cavity surface. (3) The method for producing a composite molded product according to (1) or (2), wherein the continuous reinforcing fibers contained in the sheet (A) are carbon fibers. (4) A method for producing a composite molded body according to any one of (1) to (3), in which the sheet (A) is shaped into a three-dimensional shape in an injection molding die and integrated with a material (B) containing a thermoplastic resin composition. (5) The method for producing a composite molded body according to any one of (1) to (4), wherein the cavity surface has a curved surface. (6) The method for producing a composite molded body according to any one of (1) to (5), wherein the suction is carried out using a dry vacuum pump. (7) The method for producing a composite molded product according to any one of (1) to (6), wherein the sheet (A) has a cut. (8) A method for producing a composite molded body according to any one of (1) to (7), wherein the thermoplastic resin contained in the sheet (A) and the thermoplastic resin contained in the material (B) containing a thermoplastic resin composition are both polyamide-based resins or both polyphenylene sulfide-based resins. [Effects of the Invention]

[0008] According to the present invention, the positional accuracy of the continuous fiber reinforced thermoplastic resin sheet (A) can be improved, and the thermoplastic resin constituting the material (B) containing the thermoplastic resin composition can be prevented from flowing around, thereby making it possible to obtain a composite molded product that has both good mechanical properties and moldability. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing a manufacturing apparatus for a composite molded body according to the present invention. [Figure 2] 1A to 1C are schematic diagrams showing steps in a method for producing a composite molded body according to the present invention. [Figure 3] 1A to 1C are schematic diagrams showing steps in a method for producing a composite molded body according to the present invention. [Figure 4] 1A to 1C are schematic diagrams showing steps in a method for producing a composite molded body according to the present invention. [Figure 5]FIG. 5 is a schematic diagram showing an example of a composite molded product having a three-dimensional shape, which is a composite molded product having a shape different from those produced by the injection molding die shown in FIGS. [Figure 6] FIG. 1 is a schematic perspective view showing an example of a continuous fiber reinforced thermoplastic resin sheet having incisions. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described in detail below with reference to embodiments, although the present invention is not necessarily limited to these embodiments.

[0011] The method for producing a composite molded body in the present invention is a method for producing a composite molded body by placing a sheet (A) containing continuous reinforcing fibers and a thermoplastic resin composition on the cavity surface (inner surface) of an injection molding mold, separately preparing a material (B) containing a thermoplastic resin composition, and integrating the sheet (A) with the material (B). When placing the sheet (A) on the cavity surface, the sheet (A) is sucked to stabilize its position on the cavity surface, and then the sheet (A) is integrated with the material (B) containing the thermoplastic resin composition (hereinafter sometimes referred to as material (B)).

[0012] These steps will be specifically explained with reference to FIGS.

[0013] In Fig. 1 (I), reference numeral 1 is a schematic diagram of a mold used to manufacture a composite molded body. The mold is in an open state and has two cavity surfaces 2 on which sheets (A) are placed, and each cavity surface 2 is provided with multiple fine suction ports 3. The suction ports 3 communicate with suction equipment 5 located outside the mold via fine flow channels 4 provided within the mold.

[0014] In (II) shown in Figure 2, sheet (A) is placed. Specifically, when sheet (A) 6 is brought close to cavity surface 2 while suction equipment 5 is operating, sheet (A) 6 comes into firm contact with cavity surface 2 via suction port 3, stabilizing its position. Note that, as will be described later, depending on the vacuum conditions or molding conditions, the position of sheet (A) may shift by several millimeters during subsequent molding.

[0015] In (III) shown in Figure 3, after the mold is closed, material (B) 7 containing a molten thermoplastic resin composition is injected from the cylinder of the injection molding machine into the cavity, where it reaches sheet (A) 6. If the injection is continued, sheet (A) 6 is integrated with material (B) 7 containing a thermoplastic resin composition due to the heat and pressure of the resin composition. Furthermore, sheet (A) 6 is shaped into a three-dimensional shape by the heat and pressure of the resin composition.

[0016] In (IV) shown in FIG. 4, when the injection into the mold is completed and the mold is held for a predetermined time, the material (B) containing the thermoplastic resin composition cools and solidifies, and a composite molded product 8 is obtained.

[0017] The method for producing a composite molded body according to the present invention is advantageously employed because it allows for the use of an even number of sheets (A), two of which are positioned opposite each other on the cavity surface of a mold, and allows for welding of the two sheets (A) at symmetrical positions in the resulting composite molded body with high positional accuracy. For example, two sheets (A) can be used, and the sheets can be positioned opposite each other on the cavity surface. The number of sheets (A) is preferably 10 or less. As illustrated in FIG. 2, one sheet (A) 6 is firmly attached to one cavity surface 2 by suction, and another sheet (A) 6 is firmly attached to the other cavity surface 2 facing the first cavity surface by suction. As a result, a configuration is achieved in which another sheet (A) 6 is positioned opposite the front of the first sheet (A) 6. By suctioning the two opposing sheets (A) 6 on the cavity surface 2, a composite molded product with superior mechanical properties can be obtained compared to molding in which a sheet (A) is placed on one side of the mold without a facing sheet (A). Such composite molded products exhibit minimal warpage during molding and have high dimensional accuracy. The position at which the two sheets (A) are placed facing each other depends on the shape of the composite molded product. It is important to place them where required by the design. While it is sometimes preferable to position the two sheets (A) in perfectly symmetrical positions, perfectly symmetrical placement is not always necessary. Generally, if 80% or more, preferably 90% or more, of the area of ​​one sheet (A) overlaps with the other sheet (A) facing it, the two sheets are positioned appropriately facing each other. The two sheets (A) facing each other preferably have the same shape. The opposing surfaces may have the same shape but different thicknesses, or the opposing surfaces may have different shapes and thicknesses.

[0018] Examples of continuous reinforcing fibers used in the sheet (A) of the present invention include carbon fiber and glass fiber, and it is more preferable to use carbon fiber. When carbon fiber is used, not only can the properties such as rigidity and strength of the composite molding be most efficiently improved, but also the sheet thickness can be reduced to obtain the same properties, making it easier to obtain a composite molding having a complex shape.

[0019] Examples of thermoplastic resins used for the sheet (A) in the present invention include polyamide resins (polyamide 6, polyamide 66), polyphenylene sulfide resins, acrylonitrile-butadiene-styrene copolymers, polypropylene, etc. The use of polyamide resins or polyphenylene sulfide resins is preferred, as they allow for the production of composite moldings with excellent moldability and mechanical properties. Typically, the sheet (A) is produced by impregnating continuous reinforcing fibers with a thermoplastic resin composition and forming them into a sheet.

[0020] Examples of thermoplastic resins used in material (B) containing the thermoplastic resin composition of the present invention include polyamide resins (polyamide 6, polyamide 66), polyphenylene sulfide resins, acrylonitrile-butadiene-styrene copolymers, and polypropylene. Using polyamide resins or polyphenylene sulfide resins is preferred, as it allows for the production of composite molded articles with excellent moldability and mechanical properties. Material (B) containing a thermoplastic resin composition may be a thermoplastic resin composition alone, or may contain fibers in addition to the thermoplastic resin composition. Examples of preferred fibers in this case are the same as those used in sheet (A). The continuous reinforcing fibers used in sheet (A) and the fibers contained in material (B) may be the same or different types. For example, both may be carbon fibers, or the continuous reinforcing fibers used in sheet (A) may be carbon fibers and the fibers contained in material (B) may be glass fibers.

[0021] The thermoplastic resin contained in the sheet (A) and the thermoplastic resin contained in the material (B) used in the present invention are preferably both polyamide-based resins or both polyphenylene sulfide-based resins. In this case, the sheet (A) and the material (B) are well welded together, and a composite molded product with excellent rigidity, strength, and impact resistance can be obtained. Furthermore, both the thermoplastic resin composition contained in the sheet (A) and the thermoplastic resin composition contained in the material (B) contain additives, fillers, etc. in addition to the thermoplastic resin.

[0022] The material (B) containing the thermoplastic resin composition used in the present invention may contain fillers other than carbon fiber, 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.

[0023] In the method for producing a composite molded product of the present invention, it is preferable to form sheet (A) into a three-dimensional shape in an injection mold and integrate it with material (B) containing a thermoplastic resin composition. Here, forming into a three-dimensional shape and integrating sheet (A) with material (B) means that forming and integrating are carried out simultaneously. However, both forming and integrating do not have to start and end at the same time.

[0024] In the method for producing a composite molded product of the present invention, the cavity surface of the injection molding die may have a shape with a curved surface, or the inner surface may have a shape composed of flat surfaces, but it is preferable to use an injection molding die with a shape with a curved cavity surface. Here, a shape with a curved surface means, for example, a shape with curved surfaces on both ends in the direction corresponding to the longitudinal direction of the sheet (A) (the up-down direction in Figures 1 to 4), as shown in Figures 1 to 4. Furthermore, a shape with a curved surface that can form a molded product as shown in Figure 5 may be used as an even more complex shape.

[0025] In the method for producing a composite molded product of the present invention, it is preferable to use a vacuum pump as a suction mechanism to vacuum-suck the sheet (A), and it is more preferable to use a dry vacuum pump among the vacuum pumps. Using a vacuum pump can suppress displacement of the sheet during molding and further prevent the material (B) containing the thermoplastic resin composition from getting around. Furthermore, the number and arrangement of suction ports provided on the cavity surface are not limited, but it is preferable to arrange two or more ports so that a wide area of ​​the sheet (A) is fixed to the cavity surface.

[0026] The sheet (A) in the present invention preferably has incisions as shown in Fig. 6. By having incisions, the sheet (A) can be molded into a complex three-dimensional shape without problems such as breakage or wrinkles in the sheet or breakage of the carbon fibers, and a composite molded product can be obtained that is not only excellent in rigidity and strength but also in appearance and durability.

[0027] The incisions in the 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 sheet (A) can be precisely shaped into a complex three-dimensional shape having a curved surface, and a composite molded product can be obtained that is free from breakage and wrinkles and has excellent rigidity, strength, appearance, and durability.

[0028] The length of the incisions in the sheet (A) of the present invention is preferably 1 mm or more and 50 mm or less, from the viewpoint of excellent accuracy in forming shapes having curved surfaces or complex shapes and preventing sheets from overlapping each other.

[0029] The sheet (A) having incisions can be obtained by making incisions in the sheet (A) using a laser marker, a cutting plotter, a cutting die, etc. Among these, the use of a laser marker is preferred because it allows for high-speed processing of complex incisions such as curved or zigzag lines, and the use of a cutting die is preferred because it allows for high-speed processing.

[0030] When making cuts in the sheet (A) in a direction transverse to the reinforcing fibers, some of the reinforcing fibers will be cut, but the length (average fiber length) La of the cut reinforcing fibers is not particularly limited. From the viewpoint of mechanical properties and formability, La is preferably 5 mm or more and 100 mm or less.

[0031] When making incisions in the sheet (A), the incisions may penetrate the sheet in the thickness direction, or may be made from the upper and lower surfaces of the sheet without penetrating the thickness direction. In terms of good formability of the sheet and suppressing the occurrence of wrinkles and breakage of the carbon fibers, it is preferable that the incisions penetrate the sheet in the thickness direction.

[0032] The presence or absence of cuts in sheet (A) can be confirmed by taking a photo of the surface of sheet (A) at 20x magnification using a laser microscope. The depth of the cuts in the thickness direction can also be confirmed by observing the inside of the sheet in the thickness direction using an X-ray CT device.

[0033] The thermoplastic resin contained in the 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 article are well welded together, and a composite molded article excellent in rigidity, strength, and impact resistance can be obtained. [Example]

[0034] The present invention will be described below based on examples, but the present invention is not limited to these examples.

[0035] Example 1 Dry vacuum pump with pumping speed of 0.9m 3 With the machine running at a speed of 1 / min, two sheets (A) (20 mm wide, 300 mm long, 0.2 mm thick, 50% continuous fiber content, composed of multiple carbon fibers impregnated with polyphenylene sulfide resin oriented in one direction) were placed one on each of the opposing cavity faces of the injection mold, and vacuum was applied through suction ports on each cavity face. The shape of the cavity faces was designed to match the shape of the molded product shown in Figure 5, and their longitudinal length was approximately 30 cm. Two circular suction ports with a diameter of 5 mm were provided on each cavity face, and these were connected to a vacuum pump through a flow path in the mold.

[0036] In an injection molding machine set at a cylinder temperature of 330°C and a mold temperature of 150°C, reinforced polyphenylene sulfide resin containing 40% by mass of glass fiber was injected into the mold cavity as material (B) containing a thermoplastic resin composition. As a result, a good molded product was obtained in which sheet (A) did not shift from its designated position in the composite molded product and material (B) did not wrap around to the front side (outside) of sheet (A), and a molded composite product in which sheet (A) and material (B) were firmly welded together was also obtained.

[0037] Example 2 Except for using a vacuum ejector instead of a dry vacuum pump, material (B) containing a thermoplastic resin composition was injected in the same manner as in Example 1. As a result, although sheet (A) was shifted by several millimeters from the predetermined position of the composite molded body, sheet (A) and material (B) were firmly welded together, and a composite molded body was obtained.

[0038] Example 3 Except for using a reinforced polyphenylene sulfide resin containing 30 mass% carbon fiber as material (B) containing a thermoplastic resin composition, injection of material (B) containing a thermoplastic resin composition was carried out in the same manner as in Example 1. As a result, no shifting of sheet (A) occurred, the resin composition (B) did not wrap around to the front side (outside) of sheet (A), and a molded composite product in which sheet (A) and material (B) were firmly welded together was obtained.

[0039] Example 4 Material (B) containing a thermoplastic resin composition was injected in the same manner as in Example 1, except that sheet (A) was used, on which cuts (lengthwise cuts with equal intervals of 20 mm in the length direction, widthwise intervals of 5 mm, and an alternating pattern) were made as shown in Figure 6. As a result, sheet (A) did not shift, material (B) did not wrap around to the front side (outside) of sheet (A), and a molded composite product in which sheet (A) and material (B) were firmly welded together was obtained.

[0040] Example 5 Another sheet (A) (20 mm wide, 300 mm long, 0.2 mm thick, composed of a polyamide 6 resin with a continuous fiber content of 50% by weight impregnated into a plurality of carbon fibers oriented in one direction) was used as the sheet (A), and the cylinder temperature was set to 280 ° C., and the mold temperature was set to 120 ° C. In an injection molding machine, except that a reinforced polyamide 6 resin containing 45% by mass of glass fiber was used as the material (B) containing the thermoplastic resin composition, the material (B) containing the thermoplastic resin composition was injected in the same manner as in Example 1. As a result, the sheet (A) did not shift, the resin composition (B) did not wrap around to the front side (outside) of the sheet (A), and a molded composite molded product in which the sheet (A) and the material (B) were firmly welded together was obtained.

[0041] (Comparative Example 1) Except for not operating the dry vacuum pump, injection of material (B) containing a thermoplastic resin composition was performed in the same manner as in Example 1. As a result, sheet (A) was significantly displaced from the predetermined position, material (B) was trapped between the cavity surface and sheet (A), and welding of sheet (A) and material (B) was insufficient. [Industrial Applicability]

[0042] The method for producing a composite molded article according to the present invention can be applied to the production of any composite molded article obtained by forming a continuous fiber-reinforced thermoplastic resin sheet into a three-dimensional shape and integrating it with a material containing 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]

[0043] 1. Injection mold 2 Cavity surface 3 Suction port 4 Flow path 5 Suction equipment 6. Continuous fiber reinforced thermoplastic resin sheet (A) 7. Material (B) containing a thermoplastic resin composition 8 Composite molded body 9 Cut

Claims

1. A method for producing a composite molded body, comprising: placing a continuous fiber-reinforced thermoplastic resin sheet (A) (hereinafter referred to as sheet (A)) containing continuous reinforcing fibers and a thermoplastic resin composition on a cavity surface of an injection molding die by suction; and then integrating the sheet with a material (B) containing a thermoplastic resin composition to produce a composite molded body.

2. 2. The method for producing a composite molded product according to claim 1, wherein an even number of sheets (A) are used, and two sheets are placed in positions facing each other on the cavity surface.

3. 3. The method for producing a composite molded product according to claim 1, wherein the continuous reinforcing fibers contained in the sheet (A) are carbon fibers.

4. 3. The method for producing a composite molded product according to claim 1, wherein the sheet (A) is shaped into a three-dimensional shape in an injection molding die and integrated with the material (B) containing a thermoplastic resin composition.

5. The method for producing a composite molded product according to claim 1 or 2, wherein the cavity surface has a curved surface.

6. The method for producing a composite molded product according to claim 1 or 2, wherein the suction is carried out using a dry vacuum pump.

7. The method for producing a composite molded product according to claim 1 or 2, wherein the sheet (A) has a cut.

8. 3. The method for producing a composite molded body according to claim 1 or 2, wherein the thermoplastic resin contained in the sheet (A) and the thermoplastic resin contained in the material (B) containing a thermoplastic resin composition are both polyamide-based resins or both polyphenylene sulfide-based resins.

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