Molding mold and method for manufacturing fiber-reinforced resin articles using the same

Abstract

The objective is to provide a mold that suppresses surface defects in fiber-reinforced resin articles and improves their aesthetic appeal, and a method for manufacturing fiber-reinforced resin articles using the same. [Solution] A method for manufacturing a fiber-reinforced resin article by heating and pressurizing a thermoplastic fiber-reinforced resin material using a pair of upper and lower molds, wherein the mold is provided with a vacuum line for evacuating the inside of the mold and a resin receiving section for receiving thermoplastic resin leaking from the cavity, both located outside the cavity, the thermoplastic fiber-reinforced resin material is heated to a temperature above the melting point or glass transition temperature of the thermoplastic resin matrix, then placed on the cavity surface of the mold, the mold is clamped while evacuating the mold, and the thermoplastic fiber-reinforced resin material is pressurized to form the fiber-reinforced resin article.

Description

Technical Field

[0001] The present invention relates to a molding die and a method for manufacturing a fiber reinforced resin article using the same.

Background Art

[0002] Fiber reinforced resin (FRP; Fiber Reinforced Plastic) is lightweight and has excellent mechanical properties, so it is used in various applications including automotive reinforcement members and aircraft inner panels, and its importance has been increasing in recent years. In particular, fiber reinforced thermoplastic resin articles in which the matrix resin is a thermoplastic resin are being studied in many fields because of their excellent mass productivity and recyclability.

[0003] In Patent Document 1, in the cold press molding of a thermoplastic resin material, a die provided with a specific gas flow path is used to improve the appearance of the molded product. Patent Document 2 shows a die capable of manufacturing a molded body of a thermoplastic resin fiber composite material in a high cycle by compression molding at a specific temperature rising rate, falling rate, and temperature difference.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in conventional technologies such as those of Patent Documents 1 and 2, defects may occur on the surface of the fiber reinforced resin article, resulting in a decrease in design quality. The main object of the present invention is to provide a mold that suppresses surface defects in fiber-reinforced resin articles and improves their design, and a method for manufacturing fiber-reinforced resin articles using the same. [Means for solving the problem]

[0006] As a result of diligent study in view of the aforementioned problems, the inventors have found that by providing a resin receiving section and a vacuum line around the cavity of the mold, and clamping the mold while applying vacuum, it is possible to suppress the retention of air bubbles on the surface of the resin material, and by having a structure that allows the thermoplastic resin with reduced viscosity to accumulate in the resin receiving section, the maintenance of the mold is made easier, thus completing the invention.

[0007] In other words, the present invention includes the following configuration. [1] A method for manufacturing a fiber-reinforced resin article by heating and pressurizing a thermoplastic fiber-reinforced resin material using a pair of upper and lower molds, The mold is provided with a vacuum line for evacuating the inside of the mold and a resin receiving section for receiving thermoplastic resin leaking from the cavity, both located outside the cavity. A method for manufacturing a fiber-reinforced resin article, comprising heating the thermoplastic fiber-reinforced resin material to a temperature above the melting point or glass transition temperature of the thermoplastic resin matrix, placing it on the cavity surface of the mold, clamping the mold while evacuating it, and molding the thermoplastic fiber-reinforced resin material under pressure. [2] A method for manufacturing a fiber-reinforced resin article by heating and pressurizing a thermoplastic fiber-reinforced resin material using a pair of upper and lower molds, The mold is provided with a vacuum line for evacuating the inside of the mold and a resin receiving section for receiving thermoplastic resin leaking from the cavity, both located outside the cavity. The first step involves placing the thermoplastic fiber-reinforced resin material on the cavity surface, heating the cavity surface to a temperature above the melting point or glass transition temperature of the thermoplastic resin which is the matrix of the thermoplastic fiber-reinforced resin material, then clamping the mold under vacuum and melting the thermoplastic resin under pressure, After the first step, with the mold clamped, the cavity surface is cooled to a temperature below the melting point or glass transition temperature of the thermoplastic resin to cool and solidify the thermoplastic resin, and then the mold is opened to remove the fiber-reinforced resin article in a second step. A method for manufacturing fiber-reinforced resin articles, comprising the features described above. [3]: The method for manufacturing a fiber-reinforced resin article according to [1] or [2], wherein the suction port of the vacuum line is provided outside the resin receiving portion. [4]: A method for manufacturing a fiber-reinforced resin article according to [1] or [2], wherein the suction port of the vacuum line is provided in the resin receiving portion. [5]: A pair of upper and lower molds for heating and pressurizing a thermoplastic fiber-reinforced resin material, The mold is provided with a vacuum line for evacuating the inside of the mold and a resin receiving section for receiving thermoplastic resin leaking from the cavity, both located outside the cavity. [6]: The mold according to [5], wherein the suction port of the vacuum line is provided in the resin receiving portion. [7]: The mold according to [5] or [6], wherein the resin receiving portion is provided on part or all of the periphery of the mold cavity. [Effects of the Invention]

[0008] The present invention provides a mold for suppressing surface defects in fiber-reinforced resin articles and improving their aesthetic appeal, and a method for manufacturing fiber-reinforced resin articles using the same. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic cross-sectional view showing a mold according to one embodiment. [Figure 2] This is a cross-sectional view showing the mold in the clamped state shown in Figure 1. [Figure 3] This is a schematic cross-sectional view showing a mold according to one embodiment. [Figure 4] This is a schematic cross-sectional view showing a mold according to one embodiment.

Mode for Carrying Out the Invention

[0010] Hereinafter, some embodiments of the present invention will be described with reference to the drawings as appropriate. The dimensional ratios in the drawings are for convenience of explanation and may be different from the actual ones. Also, in the drawings, the same components are denoted by the same reference numerals, and the description of overlapping components may be omitted.

[0011] [First Embodiment] The method for manufacturing a fiber-reinforced resin article according to the first embodiment is a method for manufacturing a fiber-reinforced resin article by heating and pressing a thermoplastic fiber-reinforced resin material using a pair of upper and lower molds.

[0012] (Mold) The manufacturing method according to the embodiment uses a mold provided with a vacuum line for evacuating the inside of the mold and a resin receiving portion for receiving the thermoplastic resin leaked from the cavity outside the cavity. However, the "cavity surface" is the surface that contacts the thermoplastic fiber-reinforced resin material in the cavity during molding.

[0013] FIG. 1 is a cross-sectional view schematically showing an example of a mold that can be used in the manufacturing method according to the embodiment. The mold 10 in the example shown in FIG. 1 includes an upper mold 1 and a lower mold 2. Typically, the upper mold 1 and the lower mold 2 are respectively fixed to a press machine, and the upper mold 1 can be raised and lowered.

[0014] The lower mold 2 includes a convex portion 3 that rises in a cylindrical shape along the outer periphery from the upper surface, and a concave portion 4 is formed inside thereof. An annular sealing material 5 that surrounds the outer surface is provided on the outer surface of the convex portion 3. A convex portion 6 is provided on the lower surface of the upper mold 1.

[0015] The shape of the convex portion 6 of the upper mold 1 as viewed from below and the shape of the concave portion 4 of the lower mold 2 as viewed from above are substantially the same shape, and the convex portion ⑥ is slightly smaller than the concave portion 4. As shown in Figure 2, when the upper mold 1 and the lower mold 2 are brought close together and clamped, the protrusion 6 of the upper mold 1 fits into the recess 4 of the lower mold 2, forming a cavity 9 with a shear edge formed between the inner surface of the protrusion 3 and the outer surface of the protrusion 6.

[0016] The upper surface of the protrusion 3 of the lower mold 2 is provided with a resin receiving portion 7, which is a groove for receiving thermoplastic resin that leaks out of the cavity 9 during molding. Preferably, the resin receiving portion 7 is provided around the entire circumference of the protrusion 3, that is, around the upper surface of the protrusion 3, but it may also be provided on only a part of the protrusion 3.

[0017] In the example shown in Figure 1, a vacuum line 8 for evacuating the inside of the mold 10 is provided further outward than the resin receiving portion 7 on the protrusion 3 of the lower mold 2. That is, the intake port of the vacuum line 8 opens outward from the resin receiving portion 7 on the upper surface of the protrusion 3 of the lower mold 2. The outer end of the vacuum line 8 on the outside of the mold 10 is connected to a vacuum pump 20. When the vacuum pump 20 is operated when clamping the mold 10, the pressure inside the space separated from the upper mold 1 by the sealing material 5 can be reduced.

[0018] A perforated plate or mesh may be installed at the suction port of the vacuum line 8 to prevent the inflow of molten thermoplastic resin. The vacuum line 8 can be positioned as desired depending on the shape of the cavity 9 of the mold 10. The number of vacuum lines 8 may be one or two or more.

[0019] Thus, in the mold 10, a vacuum line 8 for evacuating the inside of the cavity 9 of the mold 10 and a resin receiving portion 7 for receiving thermoplastic resin that leaks out from the cavity 9 are provided on the protrusion 3 outside the cavity 9 of the mold 10.

[0020] Each of the upper mold 1 and lower mold 2 is equipped with a heater (not shown), such as a steam heater, oil heater, or electric heater, which makes it possible to maintain the temperature of the mold 10 above the melting point or glass transition temperature of the thermoplastic resin, which is the matrix of the thermoplastic fiber-reinforced resin material.

[0021] (Thermoplastic fiber-reinforced resin material) As the thermoplastic fiber-reinforced resin material, a thermoplastic fiber-reinforced resin material (prepreg) containing a thermoplastic resin and a fiber reinforcing material can be used. More specifically, a variety of prepregs can be used, including unidirectional prepregs (UD prepregs), woven prepregs, nonwoven prepregs, SMC (sheet molding compound), and tow prepregs. Different prepregs can also be used in combination.

[0022] Typical examples of fibers used as fiber reinforcement in prepregs are carbon fibers, glass fibers, and aramid fibers, but prepregs using natural fibers such as plant fibers can also be preferably used.

[0023] The thermoplastic resin that forms the matrix of the thermoplastic fiber-reinforced resin material is not particularly limited, and examples include polypropylene (PP), polyetherimide (PEI), polysulfone (PSU), polyethersulfone (PES), polyphenylene sulfone (PPSU), polyphthalamide (PPA), polyphenylene ether (PPO), polyetheretherketone (PEEK), polyphenylene sulfide (PPS), polyamide (PA), polyaryletherketone (PAEK), polyetherketoneketone (PEKK), and polycarbonate (PC). These thermoplastic resins may be used individually or in combination of two or more.

[0024] (Manufacturing method) Below, an example of a manufacturing method for a fiber-reinforced resin article according to the embodiment will be described using the mold 10 mentioned above. In this embodiment, the thermoplastic fiber-reinforced resin material 30 is heated to a temperature above the melting point or glass transition temperature of the thermoplastic resin matrix. Then, as shown in Figure 1, the plasticized thermoplastic fiber-reinforced resin material 30 is placed on the cavity surface of the lower mold 2 of the mold 10, which has been adjusted to a temperature below the melting point or glass transition temperature of the thermoplastic resin. Subsequently, as shown in Figure 2, the mold 10 is clamped while the cavity 9 is evacuated through the vacuum line 8, and the thermoplastic fiber-reinforced resin material 30 is pressed and molded. Next, the mold 10 is opened, and the cooled and solidified fiber-reinforced resin article is removed. This yields a fiber-reinforced resin article in which the thermoplastic fiber-reinforced resin material 30 has been molded into the desired shape.

[0025] The heating temperature for thermoplastic fiber-reinforced resin materials is preferably 5 to 40°C higher than the melting point or glass transition temperature of the thermoplastic resin, and more preferably 5 to 20°C higher. The temperature of the mold 10 should be below the melting point or glass transition temperature of the thermoplastic resin, preferably 50°C or more lower than the melting point or glass transition temperature of the thermoplastic resin, and more preferably 150°C or more lower.

[0026] The vacuum pressure inside the cavity 9 when the system is evacuated is preferably 0.1 MPa or less, more preferably 0.5 MPa or less. The molding pressure is preferably 0.5 to 5 MPa, more preferably 0.5 to 3 MPa. The molding pressure is defined as the value obtained by dividing the pressing force of the press machine by the vertical projected area of ​​the cavity.

[0027] By molding the thermoplastic fiber-reinforced resin material 30 under vacuum conditions using the upper mold 1 and lower mold 2 within the cavity 9 of the mold 10, air bubbles can be easily removed from the thermoplastic resin whose viscosity has decreased due to heating. As a result, air bubbles are less likely to remain on the surface of the thermoplastic fiber-reinforced resin material 30, surface defects in the resulting fiber-reinforced resin article are suppressed, improving the aesthetic appearance and preventing a decrease in mechanical properties. Furthermore, since a resin receiving section 7 is provided on the outside of the cavity 9, even if the thermoplastic resin with reduced viscosity leaks out of the cavity 9, it will accumulate in the resin receiving section 7 and will not flow into the vacuum line 8, making mold maintenance easy and allowing for repeated use.

[0028] [Second Embodiment] The following describes a method for manufacturing a fiber-reinforced resin article according to the second embodiment. The method for manufacturing a fiber-reinforced resin article according to the second embodiment is the same as in the first embodiment, in which a thermoplastic fiber-reinforced resin material is heated and pressurized using a pair of upper and lower molds to produce a fiber-reinforced resin article. An example of a mold used in the second embodiment is the mold 10 described above.

[0029] The method for manufacturing a fiber-reinforced resin article according to the second embodiment includes the following first and second steps. First step: The thermoplastic fiber-reinforced resin material is placed on the cavity surface. After heating the cavity surface to a temperature above the melting point or glass transition temperature of the thermoplastic resin which is the matrix of the thermoplastic fiber-reinforced resin material, the mold is clamped and the thermoplastic resin is melted under pressure. Second step: With the mold clamped, the cavity surface is cooled to a temperature below the melting point or glass transition temperature of the thermoplastic resin to cool and solidify the thermoplastic resin, after which the mold is opened and the fiber-reinforced resin article is removed. Below, as an example of a manufacturing method according to the second embodiment, a method using a mold 10 will be described.

[0030] (First step) As shown in Figure 1, a thermoplastic fiber-reinforced resin material 30 is placed on the cavity surface of the lower mold 2. After heating the upper mold 1 and lower mold 2 of the mold 10 to above the melting point or glass transition temperature of the thermoplastic resin which is the matrix of the thermoplastic fiber-reinforced resin material, the mold 10 is clamped under vacuum and the thermoplastic resin is melted under pressure. The heating temperature of the mold 10 is preferably 5 to 40°C higher than the melting point or glass transition temperature of the thermoplastic resin, and more preferably 5 to 20°C higher.

[0031] The vacuum pressure inside the cavity 9 when the system is evacuated is preferably 0.1 MPa or less, more preferably 0.5 MPa or less. The molding pressure is preferably 0.5 to 5 MPa, more preferably 0.5 to 3 MPa.

[0032] (Second step) With the mold 10 clamped, the cavity surface of the mold 10 is cooled to a temperature below the melting point or glass transition temperature of the thermoplastic resin, allowing the thermoplastic resin to cool and solidify. Then, the mold 10 is opened and the fiber-reinforced resin article is removed. The temperature of the mold 10 during cooling and solidification should be below the melting point or glass transition temperature of the thermoplastic resin, preferably 50°C or more lower than the melting point or glass transition temperature of the thermoplastic resin, and more preferably 150°C or more lower.

[0033] In the second embodiment as well, by molding the thermoplastic fiber-reinforced resin material 30 under vacuum in the cavity 9 of the mold 10, air bubbles can be easily removed from the thermoplastic resin whose viscosity has decreased. As a result, air bubbles are less likely to remain on the surface of the thermoplastic fiber-reinforced resin material 30, surface defects in the resulting fiber-reinforced resin article are suppressed, and the aesthetic appeal is improved. Furthermore, a resin receiving section 7 is provided on the outside of the cavity 9. Even if the thermoplastic resin with reduced viscosity leaks out of the cavity 9, it accumulates in the resin receiving section 7 and does not flow into the vacuum line 8, making mold maintenance easy and allowing for repeated use.

[0034] [Example of modification] The present invention is not limited to the mold and manufacturing method using the mold described above. For example, the mold 10A illustrated in Figure 3 and the manufacturing method using the mold 10A may also be used. In mold 10A, the same parts as in mold 10 are denoted by the same reference numerals and their descriptions are omitted. In mold 10A, a vacuum line 8A is provided such that an intake port opens into the resin receiving portion 7 of the protrusion 3 of the lower mold 2. That is, the intake port of the vacuum line 8A is provided in the resin receiving portion 7. In the mold 10A as well, by operating the vacuum pump 20 while the mold is clamped and suction is performed through the vacuum line 8A, the space separated from the upper mold 1 and the sealing material 5 can be depressurized.

[0035] A perforated plate or mesh may be installed at the suction port of the vacuum line 8A to prevent the inflow of molten thermoplastic resin. The vacuum line 8A can be positioned as desired depending on the shape of the cavity 9 of the mold 10. The number of vacuum lines 8A may be one or two or more.

[0036] The mold 10B shown in Figure 4 and the manufacturing method using the mold 10B may also be used. In mold 10B, the same parts as in mold 10 are given the same reference numerals and their descriptions are omitted. In mold 10B, a vacuum line 8B is provided outside the protrusion 6 of the upper mold 1, that is, outside the cavity. In the mold 10B as well, by operating the vacuum pump 20 while the mold is clamped and suction is performed through the vacuum line 8B, the space separated from the upper mold 1 and the sealing material 5 can be depressurized.

[0037] A perforated plate or mesh may be installed at the suction port of the vacuum line 8B to prevent the inflow of molten thermoplastic resin. The vacuum line 8B can be positioned as desired depending on the shape of the cavity 9 of the mold 10. The number of vacuum lines 8B may be one or two or more.

[0038] The present invention may also include a mold in which vacuum lines are provided on both the upper and lower molds, and a manufacturing method using the said mold. Furthermore, without departing from the spirit of the present invention, the components in the above embodiments may be replaced with well-known components as appropriate, and the above-described modifications may be combined as appropriate. [Explanation of symbols]

[0039] 1 Upper mold 2 Lower mold 3. Convex part 4 recesses 5. Sealant 6. Convex part 7 Resin receiving part 8,8A,8B Vacuum lines 9 Cavity 10, 10A, 10B molds 30 Thermoplastic fiber-reinforced resin materials

Claims

1. A method for manufacturing a fiber-reinforced resin article by heating and pressurizing a thermoplastic fiber-reinforced resin material using a pair of upper and lower molds, The mold is provided with a vacuum line for evacuating the inside of the mold and a resin receiving section for receiving thermoplastic resin leaking from the cavity, both located outside the cavity. A method for manufacturing a fiber-reinforced resin article, comprising heating the thermoplastic fiber-reinforced resin material to a temperature above the melting point or glass transition temperature of the thermoplastic resin matrix, placing it on the cavity surface of the mold, clamping the mold while evacuating it, and molding the thermoplastic fiber-reinforced resin material under pressure.

2. A method for manufacturing a fiber-reinforced resin article by heating and pressurizing a thermoplastic fiber-reinforced resin material using a pair of upper and lower molds, The mold is provided with a vacuum line for evacuating the inside of the mold and a resin receiving section for receiving thermoplastic resin leaking from the cavity, both located outside the cavity. The first step involves placing the thermoplastic fiber-reinforced resin material on the cavity surface, heating the cavity surface to a temperature above the melting point or glass transition temperature of the thermoplastic resin which is the matrix of the thermoplastic fiber-reinforced resin material, then clamping the mold under vacuum and melting the thermoplastic resin under pressure, After the first step, with the mold clamped, the cavity surface is cooled to a temperature below the melting point or glass transition temperature of the thermoplastic resin to cool and solidify the thermoplastic resin, and then the mold is opened to remove the fiber-reinforced resin article in a second step. A method for manufacturing fiber-reinforced resin articles, comprising the features described above.

3. The method for manufacturing a fiber-reinforced resin article according to claim 1 or 2, wherein the suction port of the vacuum line is provided outside the resin receiving portion.

4. A method for manufacturing a fiber-reinforced resin article according to claim 1 or 2, wherein the suction port of the vacuum line is provided in the resin receiving portion.

5. A pair of upper and lower molds for heating and pressurizing a thermoplastic fiber-reinforced resin material, The mold is provided with a vacuum line for creating a vacuum inside the mold and a resin receiving section for receiving thermoplastic resin leaking from the cavity, both located outside the cavity.

6. The mold according to claim 5, wherein the suction port of the vacuum line is provided in the resin receiving portion.

7. The mold according to claim 5, wherein the resin receiving portion is provided on part or all of the periphery of the mold cavity.

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