JP2013010255A - Thermoplastic resin composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite molding having superior rigidity, in a carbon fiber composite molding comprising a carbon fiber and a thermoplastic resin.SOLUTION: This composite material comprises: a random mat material comprising a reinforced fiber having a fiber length of 10 to 100 mm and a thermoplastic resin (A), wherein the amount of thermoplastic resin (A) is 10 to 1,000 pts.wt. based on 100 pts.wt. of the reinforced fiber, and the reinforced fiber is substantially two dimensionally and randomly oriented; and a unidirectional material provided on at least one surface of the random mat material and obtained by impregnating the reinforced fiber drawn and aligned in one direction with a thermoplastic resin (B) including semi-aromatic polyamide.

Description

  The present invention relates to a carbon fiber reinforced composite molded article composed of carbon fibers and a thermoplastic resin having excellent rigidity.

As a fiber reinforced composite molded body using carbon fiber, aramid fiber, glass fiber or the like as a reinforcing fiber, an isotropic random mat is used because of formability and simplicity of the process.
In recent years, as means for improving the mechanical properties of a composite molded body using a random mat, a method using a chopped fiber bundle in which a fiber bundle is cut obliquely and a cross-sectional area is changed has been proposed (Patent Documents 1 and 2). ). However, these are only proposals for composite molded bodies having a thermosetting resin as a matrix.

In addition, a technique for injection-molding long fiber pellets containing carbon fibers has been proposed for a composite molded body using a thermoplastic resin as a matrix (Patent Document 3), but the length of the pellets is limited to the length of the long fiber pellets. Furthermore, the carbon fibers are cut in the thermoplastic resin by kneading, and there is a problem that the length of the carbon fibers cannot be maintained. Further, such a molding method by injection molding has a problem that the carbon fibers are oriented and an isotropic material cannot be obtained.
Further, Patent Documents 3 and 4 disclose that a reinforcing fiber composite material having a semi-aromatic polyamide as a matrix resin has high rigidity. However, these are all for injection molding using reinforcing fiber short fibers, and a reinforcing fiber composite material using continuous fibers of semi-aromatic polyamide and reinforcing fibers is not disclosed.

JP 2009-114611 A JP 2009-114612 A Japanese Patent Laid-Open No. 9-286036 Japanese Patent No. 4609984 JP-A-7-109421

From the background art described above, it has been desired to develop a carbon fiber composite material composed of carbon fiber and thermoplastic resin and having excellent rigidity.
Accordingly, an object of the present invention is to provide a composite molded body having excellent rigidity in a carbon fiber composite molded body composed of carbon fibers and a thermoplastic resin.

In order to solve the above problems, the present invention is composed of carbon fibers having a fiber length of 10 to 100 mm and a thermoplastic resin (A), and the abundance of the thermoplastic resin (A) is 100 parts by weight of carbon fibers. 10 to 1000 parts by weight, a random mat base material in which carbon fibers are substantially two-dimensionally oriented;
A composite molded body comprising: a unidirectional material formed by impregnating a thermoplastic resin (B) containing a semi-aromatic polyamide into carbon fibers provided on at least one side of the random mat base material and aligned in one direction. I will provide a.

The composite molded body of the present invention preferably contains at least one selected from the group consisting of aliphatic polyamide and semi-aromatic polyamide as the thermoplastic resin (A).
Furthermore, in the composite molded body of the present invention, the semi-aromatic polyamide in the thermoplastic resin (B) is preferably at least one selected from the group consisting of MXD nylon and nylon 6T.
And it is preferable that the composite molded object of this invention is a thing obtained by press molding.

  ADVANTAGE OF THE INVENTION According to this invention, it is a composite molded object comprised from carbon fiber and a thermoplastic resin, Comprising: The composite molded object excellent in rigidity can be provided.

It is the schematic (perspective view and sectional drawing) of the molded object created in Example 16.

Hereinafter, the present invention will be described in detail.
[Carbon fiber]
Any carbon fiber such as polyacrylonitrile (PAN), petroleum / coal pitch, rayon, and lignin can be used as the carbon fiber constituting the composite molded body of the present invention. In particular, PAN-based carbon fibers using PAN as a raw material are preferable because they are excellent in productivity and mechanical properties on an industrial scale.
Specifically, PAN-based carbon fibers having an average diameter of 5 to 10 μm can be used. As the PAN-based carbon fiber, a fiber bundle of 1000 to 50000 short fibers can be used.
In order to enhance the adhesion between the carbon fiber and the matrix resin, it is also preferable to use a material in which an oxygen-containing functional group is introduced on the surface of the carbon fiber by a surface treatment. As the surface treatment method, known methods include liquid phase and gas phase treatment, but liquid phase electrolytic surface treatment is preferable from the viewpoint of productivity, stability, price and the like.
Moreover, the handleability of a carbon fiber bundle can be improved by giving a sizing agent to the carbon fiber to make a carbon fiber bundle, and the composite molded body of the present invention can be preferably obtained.

[Random mat substrate]
The random mat base material constituting the composite molded body of the present invention is composed of carbon fibers having a fiber length of 10 to 100 mm and a thermoplastic resin (A), and the abundance of the thermoplastic resin (A) is 100 weights of carbon fibers. 10 to 1000 parts by weight with respect to parts, and carbon fibers are substantially two-dimensionally oriented randomly.
The composite molded body of the present invention is characterized by excellent torsional rigidity because it has a random mat base material in which carbon fibers are oriented substantially two-dimensionally at random.

  The type of the thermoplastic resin (A) constituting the random mat base material is not particularly limited. For example, nylon 6, nylon 66, nylon 11, nylon 12, nylon 6,9, nylon 6,10, nylon 6,12, etc. Selected from the group consisting of aliphatic polyamides, MXD nylon, nylon 6T, nylon 9T, nylon 6I, nylon 9I and other semi-aromatic polyamides, polyethylene terephthalate, polybutylene terephthalate, polyester such as polybutylene naphthalate, and polyolefins such as polypropylene. Can be used. Various copolymers can also be used. As the thermoplastic resin (A), those containing at least one of an aliphatic polyamide and a semi-aromatic polyamide are preferably used in terms of mechanical properties, heat resistance, cost, and the like. At this time, the blending ratio of at least one of aliphatic polyamide or semi-aromatic polyamide in the thermoplastic resin (A) is preferably 20 parts by weight or more in 100 parts by weight of the thermoplastic resin (A).

The abundance of the thermoplastic resin (A) in the random mat substrate is preferably 10 to 1000 parts by weight with respect to 100 parts by weight of the carbon fibers. More preferably, it is 50-500 weight part with respect to 100 weight part of carbon fibers, More preferably, it is 50-100 weight part with respect to 100 weight part of carbon fiber.
The thickness of the random mat substrate is not particularly limited, and can be appropriately selected depending on the application. Further, a plurality of random mat substrates can be stacked and used as necessary.

For the random mat base material, various fibrous or non-fibrous fillers such as glass fibers and organic fibers, flame retardants, UV-resistant agents, pigments, mold release agents, and softening agents are used within the range not impairing the object of the present invention. In addition, additives such as a plasticizer and a surfactant may be included.
In the random mat substrate used in the present invention, the thermoplastic resin (A) is preferably present in the form of fibers, powders, or granules.

In addition, the random mat substrate used in the present invention,
1. 1. Step of cutting the carbon fiber bundle 2. Step of opening the fiber bundle by introducing the cut carbon fiber into the tube and blowing air onto the fiber. 3. Step of simultaneously spreading carbon fiber and thermoplastic resin while diffusing the opened carbon fiber and simultaneously sucking it together with the thermoplastic resin It can preferably be obtained by a step of fixing the dispersed carbon fibers and thermoplastic resin.

[One-way material]
The unidirectional material constituting the composite molded body of the present invention is a thermoplastic resin (B) containing a semi-aromatic polyamide in carbon fibers provided on at least one side of the random mat base material and aligned in one direction. It is impregnated. In the present invention, the unidirectional material may be a laminate of a plurality of unidirectional materials, and a laminate of carbon fiber bundles aligned in one direction in a sheet shape and changing the angle (multiaxial fabric) The base material) is stitched with nylon yarn, polyester yarn, glass fiber yarn, etc., and this laminate is passed through in the thickness direction, and stitched by reciprocating between the front and back surfaces of the laminate along the surface direction. Such a multiaxial fabric may be used.

  The thermoplastic resin (B) constituting the unidirectional material contains semi-aromatic polyamide. Although the kind of semi-aromatic polyamide is not particularly limited, it is preferably at least one selected from MXD nylon and nylon 6T. By using these semi-aromatic polyamides, it is possible to obtain a composite molded body having higher rigidity.

  In the thermoplastic resin (B), a semi-aromatic polyamide resin and another resin can be used in combination. In this case, other resins used are not particularly limited, and for example, aliphatic polyamides such as nylon 6, nylon 66, nylon 11, nylon 12, nylon 6,9, nylon 6,10, nylon 6,12 and the like are preferable. Can be used. In the present invention, even if the thermoplastic resin (A) used for the random mat base material and the thermoplastic resin (B) used for the unidirectional material are different resins, the obtained composite molded body has high rigidity. This point is specific.

  The blending ratio of the semi-aromatic polyamide in the thermoplastic resin (B) is preferably 10 to 100 parts by weight in 100 parts by weight of the thermoplastic resin (B). By setting it as 10 weight part-100 weight part, the reinforcement effect of a mechanical characteristic is large, and it becomes what was excellent in chemical resistance. More preferably, it is 20 to 100 parts by weight.

The abundance of the thermoplastic resin in the unidirectional material is preferably 10 to 1000 parts by weight with respect to 100 parts by weight of the carbon fibers. More preferably, it is 50-500 weight part with respect to 100 weight part of carbon fibers, More preferably, it is 50-100 weight part with respect to 100 weight part of carbon fiber.
The thickness of the unidirectional material is not particularly limited and can be appropriately selected depending on the application. Further, a plurality of unidirectional materials can be stacked and used as necessary.

  The fiber volume content Vf of the unidirectional material is not particularly limited, but is preferably 20% to 80%, and particularly preferably 30% to 70%. By setting Vf in such a range, the resulting composite molded body can have high rigidity and can easily be impregnated with resin in a unidirectional material.

  The method for producing the unidirectional material is not particularly limited, and can be obtained by, for example, a pultrusion method. In the case of the pultrusion method, carbon fibers impregnated with a thermoplastic resin are preferably obtained. When the impregnation with a thermoplastic resin is suppressed, that is, when semi-impregnation is used, for example, a method in which carbon fibers are aligned in one direction on a sheet made of a thermoplastic resin and heated while pressing if necessary is preferable. Can be obtained. Here, the degree of impregnation or semi-impregnation can be appropriately adjusted in the press step of the production method described later.

[Composite molded body]
The composite molded body of the present invention comprises the above-mentioned random mat substrate and the above-mentioned unidirectional material provided on at least one surface of the random mat substrate.

  A random mat substrate and a unidirectional material having a desired thickness can be used. Although the thickness of a random mat base material is not specifically limited, Preferably it is 0.1-5 mm. Although the thickness of a unidirectional material is not specifically limited, It is 0.1-5 mm.

The volume ratio, the area ratio, and the lamination part of the random mat base material and the unidirectional material can be appropriately selected according to various uses. In this case, it is preferable for the purpose of the present invention that the unidirectional material is present in an amount of 5 to 50% by volume based on the total volume of the composite molded body. Among them, the unidirectional material is preferably arranged so as to effectively exhibit desired torsional rigidity and bending rigidity. Specifically, it is desirable that the inside of the molded body be a random mat base material and the outside be a unidirectional material.
In order to further utilize the high tensile properties of the unidirectional material, it is preferable to laminate the unidirectional material on the tensile side with respect to the bending deformation direction of the molded body.

  There is no particular restriction on the method of combining the random mat base material and the unidirectional material, but the method of press molding in a state where the random mat base material and the unidirectional material are combined, or the random mat base material and the unidirectional material are combined. For example, a method of pre-impregnating and making them easy to handle and then bonding them together and press-molding may be mentioned.

  It is also possible to obtain a molded body having a desired shape such as a three-dimensional shape by selecting the shape of the mold at the time of molding. The composite molded body of the present invention has a short resin transfer time in the pressing step, enables impregnation of the resin in a relatively short time, and can provide a molded body having excellent physical properties and excellent surface quality. Further, in the random mat base material used in the molded body of the present invention, carbon fibers are isotropic, so that even if reinforced in one direction, a uniform molded body with less warpage can be easily obtained. Can do. It is also possible to obtain a composite molded body by sticking a random mat base material to the surface layer of a member having an open cross-sectional shape or a closed cross-sectional shape obtained by pultrusion molding, for example, by a tape layup method.

  As long as the composite molded body of the present invention comprises a random mat substrate and a unidirectional material provided on at least one side of the random mat substrate, the laminated structure is not particularly limited. A sandwich structure using a plurality of materials and unidirectional materials is also preferable. That is, the present invention includes a sandwich material having a random mat substrate as a skin layer and a unidirectional material as a core layer, and a sandwich material having a random mat substrate as a core layer and a unidirectional material as a skin layer.

In the case of a sandwich material having a random mat base material as a skin layer, it is excellent in design and the like, and is excellent in prevention of cracking due to impact load. Therefore, it is particularly suitable for use in structural members such as bicycles and railways.
Further, in the case of a sandwich material having a random mat base material as a core layer, it becomes easy to achieve both mechanical properties, particularly strength and rigidity, and therefore, it is particularly suitably used for structural members such as buildings.

  The composite molded article of the present invention exhibits high mechanical strength and can be used for various components such as an inner plate and an outer plate of an automobile, various electric products, a frame of a machine, and a casing. Since the composite molded body of the present invention is particularly excellent in synthesis, it can be applied to automobile components having an open section structure or a closed section structure, particularly side members, cross members, side pillars, floor pans, and the like.

Examples are shown below, but the present invention is not limited thereto.
[raw materials]
Polyamide resin Nylon 6 Made by Unitika Ltd. Emblem ON (registered trademark)
Nylon 66 Nylon 2015B (registered trademark) manufactured by Ube Industries, Ltd.
Semi-aromatic polyamide resin MXD nylon Mitsubishi Gas Chemical Co., Ltd. Reny 6007 (registered trademark)
Nylon 6T TY-521TNs (registered trademark) manufactured by Toyobo Co., Ltd.

[Method of measuring bending properties of composite molded body molded plate]
The bending tests in the following examples were evaluated by three-point bending by cutting out a test piece having a width of 15 mm and a length of 100 mm from a molded plate and using a center load in accordance with JIS K7074. Maximum load and center deflection when a test piece is placed on a fulcrum of r = 2mm with a fulcrum distance of 80mm and a load is applied at a test speed of 5mm / min with an indenter of r = 5mm in the center between the fulcrum The bending strength and the bending elastic modulus were measured. The surface that the indenter contacts during the test was the compression side, and the opposite surface was the tension side.

[Reference Example 1]
As the carbon fiber, carbon fiber “Tenax” (registered trademark) STS40-24KS (fiber diameter 7 μm, tensile strength 4000 MPa) manufactured by Toho Tenax Co., Ltd. was used. A rotary cutter that forms a knife using cemented carbide was used as the cutting device. The angle of the knife was 90 degrees with the circumferential direction, and a knife with a blade width of 1 mm was used. The knives were arranged at a pitch of 16 mm in the circumferential direction, and adjacent knives were arranged so as to be offset from each other by 1 mm in the circumferential direction. A tube having small holes was prepared as a fiber opening device, and compressed air was supplied using a compressor. At this time, the wind speed from the small hole was 100 m / sec. This tube was placed directly under the rotary cutter. Next, a table movable in the XY directions was installed at the lower part of the taper tube outlet, and suction was performed from the lower part of the table with a blower. And when the supply amount of carbon fiber was set to 150 g / min and the apparatus was operated, a carbon fiber mat having an average fiber length of 16 mm and a thickness of 0.5 mm was obtained.

[Reference Example 2]
Nylon 6 resin film (Emblem ON (registered trademark) manufactured by Unitika Co., Ltd.) was placed on the random mat obtained in Reference Example 1 so that the resin was 150 parts by volume with respect to 100 parts by volume of carbon fiber. A press apparatus heated to 260 ° C. was heated at 2.0 MPa for 5 minutes to obtain a molded plate having a thickness t = 0.2 mm and Vf of 40%.

[Reference Example 3]
Using a film of nylon 66 resin (nylon 2015B (registered trademark) manufactured by Ube Industries, Ltd.), a molded plate of t = 0.2 mm and Vf 40% was obtained in the same manner as in Reference Example 2.

[Reference Example 4]
MXD nylon Using a Reny 6007 (registered trademark) film manufactured by Mitsubishi Gas Chemical Co., Inc., a molded plate of t = 0.2 mm and Vf 40% was obtained in the same manner as in Reference Example 2.

[Reference Example 5]
MXD nylon The same method as in Reference Example 2, except that a Reny 6007 (registered trademark) film manufactured by Mitsubishi Gas Chemical Co., Ltd. was used and the ratio of carbon fiber to resin was changed to 400 parts by volume of resin with respect to 100 parts by volume of carbon fiber. Thus, a molded plate of t = 0.2 mm and Vf 20% was obtained.

[Reference Example 6]
A unidirectional material composed of continuous fibers of carbon fiber (manufactured by Toho Tenax Co., Ltd., Tenax (registered trademark) STS40-24KS (fiber diameter 7 μm, tensile strength 4000 MPa), and 100 parts by volume of resin with respect to 100 parts by volume of carbon fiber; In this way, a film of MXD Nylon Mitsubishi Gas Chemical Co., Ltd. Reny 6007 (registered trademark) was placed and bonded with a 260 ° C. heating roller to obtain a unidirectional material with t = 0.02 mm and Vf of 50%.

[Reference Example 7]
A unidirectional material composed of continuous fibers of carbon fiber (manufactured by Toho Tenax Co., Ltd., Tenax (registered trademark) STS40-24KS (fiber diameter 7 μm, tensile strength 4000 MPa), and 43 parts by volume of resin with respect to 100 parts by volume of carbon fiber; MXD Nylon Mitsubishi Gas Chemical Co., Ltd. Reny 6007 (Registered Trademark) film was placed, heated in a press apparatus heated to 260 ° C. at 6.0 MPa for 5 minutes, t = 0.2 mm, A molded plate of Vf 70% was obtained.

[Reference Example 8] A nylon 6 resin film (Unitika Emblem ON (registered trademark)) was used to obtain a unidirectional material of t = 0.02 mm and Vf 50% in the same manner as in Reference Example 6.

[Reference Example 9]
Nylon 6T Unidirectional material with t = 0.02 mm and Vf of 50% in the same manner as in Reference Example 6 except that a film of TY-521TNs (registered trademark) manufactured by Toyobo Co., Ltd. was used and the molding temperature was 320 ° C. Got.

[Reference Example 10]
MXD Nylon Mitsubishi Gas Chemical Co., Ltd. Reny 6007 (registered trademark) and Nylon 6 resin Unitika Co., Ltd. Emblem ON (registered trademark) films are used, and the respective volume ratios are MXD nylon: nylon 6 = 20: 80. Thus, a unidirectional material of t = 0.02 mm and Vf of 50% impregnated with a blend resin of MXD nylon and nylon 6 was obtained.

[Reference Example 11]
MXD Nylon Mitsubishi Gas Chemical Co., Ltd. Reny 6007 (registered trademark) and nylon 6 resin Unitika Co., Ltd. emblem ON (registered trademark) film, each volume ratio is MXD nylon: nylon 6 = 80:20 Thus, a unidirectional material of t = 0.02 mm and Vf of 50% impregnated with a blend resin of MXD nylon and nylon 6 was obtained.

[Example 1]
The random mat substrate (nylon 6) Vf 40% obtained in Reference Example 2 was used as the core material, and the unidirectional material (MXD nylon) Vf 50% obtained in Reference Example 6 was used as the skin material. First, a random mat base material (nylon 6) was cut into a size of 30 cm wide × 50 cm long and overlapped by 10 sheets. Four layers of unidirectional material (MXD nylon) were bonded to both sides. At the time of bonding, a soldering iron heated to 300 ° C. was used to weld and fix the resin. The thicknesses of the respective materials are 0.08 mm, 2.00 mm, and 0.08 mm for the unidirectional material (upper surface side), the random mat base material, and the unidirectional material (lower surface side), respectively. A press apparatus heated to 300 ° C. was heated at 2.0 MPa for 5 minutes to obtain a molded article having t = 2.16 mm. About the obtained molded object, the bending characteristic was evaluated using the above-mentioned method.

[Example 2]
In the same manner as in Example 1, using the random mat base material (nylon 66) Vf 40% obtained in Reference Example 3 as the core material and the unidirectional material (MXD nylon) Vf 50% obtained in Reference Example 6 as the skin material. A molded body was obtained. The bending property was evaluated about the obtained molded object using the above-mentioned method.

[Example 3]
Random mat base material (nylon 6) Vf 40% obtained in Reference Example 2 was used as the core material, and the unidirectional material (6T nylon) Vf 50% obtained in Reference Example 9 was used as the skin material, except that the molding temperature was 320 ° C. Obtained a molded body in the same manner as in Example 1. The bending property was evaluated about the obtained molded object using the above-mentioned method.

[Example 4]
In the same manner as in Example 3, the random mat base material (nylon 66) Vf 40% obtained in Reference Example 3 was used as the core material, and the unidirectional material (6T nylon) Vf 50% obtained in Reference Example 9 was used as the skin material. A molded body was obtained. The bending property was evaluated about the obtained molded object using the above-mentioned method.

[Example 5]
In the same manner as in Example 1, using the random mat substrate (MXD nylon) Vf 20% obtained in Reference Example 5 as the core material and the unidirectional material (MXD nylon) Vf 50% obtained in Reference Example 6 as the skin material. A molded body was obtained. The bending property was evaluated about the obtained molded object using the above-mentioned method.

[Example 6]
In the same manner as in Example 1, using the random mat substrate (MXD nylon) Vf 40% obtained in Reference Example 4 as the core material and the unidirectional material (MXD nylon) Vf 70% obtained in Reference Example 7 as the skin material. A molded body was obtained. The bending property was evaluated about the obtained molded object using the above-mentioned method.

[Example 7]
Random mat base material (MXD nylon) Vf 40% obtained in Reference Example 4 was used as the core material, and unidirectional material (MXD nylon) Vf 50% obtained in Reference Example 6 was used as the skin material. First, a random mat base material (nylon 6) was cut into a size of 30 cm wide × 50 cm long and overlapped by 10 sheets. Four layers of unidirectional material (MXD nylon) were bonded to only the lower surface. At the time of bonding, a soldering iron heated to 300 ° C. was used to weld and fix the resin. The thicknesses of the respective materials are 0 mm, 2.00 mm, and 0.08 mm for the unidirectional material (upper surface side), the random mat base material, and the unidirectional material (lower surface side), respectively. A press apparatus heated to 300 ° C. was heated at 2.0 MPa for 5 minutes to obtain a molded article having t = 2.16 mm. About the obtained molded object, the bending characteristic was evaluated using the method shown in the section of [Measurement method of bending properties of composite molded object molded plate]. At that time, the evaluation was performed in such a manner that the indenter was in contact with the surface on which the unidirectional material was not bonded.

[Example 8]
A molded body was obtained in the same manner as in Example 7, except that the unidirectional material (MXD nylon) was bonded to 8 layers. The bending property was evaluated about the obtained molded object using the above-mentioned method.

[Example 9]
Random mat base material (MXD nylon) Vf 40% obtained in Reference Example 4 was used as the core material, and unidirectional material (MXD nylon) Vf 50% obtained in Reference Example 6 was used as the skin material. First, a random mat base material (nylon 6) was cut into a size of 30 cm wide × 50 cm long and overlapped by 10 sheets. Four layers of unidirectional material (MXD nylon) were bonded to only the upper surface. At the time of bonding, a soldering iron heated to 300 ° C. was used to weld and fix the resin. The thicknesses of the respective materials are 0.08 mm, 2.00 mm, and 0 mm for the unidirectional material (upper surface side), the random mat base material, and the unidirectional material (lower surface side), respectively. A press apparatus heated to 300 ° C. was heated at 2.0 MPa for 5 minutes to obtain a molded article having t = about 2.08 mm. The bending property was evaluated about the obtained molded object using the above-mentioned method. At that time, the evaluation was performed in such a manner that the indenter was in contact with the surface on which the unidirectional material was laminated.

[Example 10]
A molded body was obtained in the same manner as in Example 9 except that the unidirectional material (MXD nylon) was bonded to 8 layers. The bending property was evaluated about the obtained molded object using the above-mentioned method.

[Example 11]
Random mat base material (MXD nylon) Vf 40% obtained in Reference Example 4 was used as the core material, and unidirectional material (MXD nylon) Vf 50% obtained in Reference Example 6 was used as the skin material. First, a random mat base material (nylon 6) was cut into a size of 30 cm wide × 50 cm long and overlapped by 10 sheets. Next, 8 layers of unidirectional material (MXD nylon) were bonded to the upper and lower sides. At the time of bonding, a soldering iron heated to 300 ° C. was used to weld and fix the resin. The thicknesses of the respective materials are 0.15 mm, 2.00 mm, and 0.15 mm for the unidirectional material (upper surface side), the random mat base material, and the unidirectional material (lower surface side), respectively. In a press apparatus heated to 300 ° C., it was heated at 2.0 MPa for 5 minutes to obtain a molded product having t = about 2.30 mm. The bending property was evaluated about the obtained molded object using the above-mentioned method. At that time, the evaluation was performed in such a manner that the indenter was in contact with the surface on which the unidirectional material was not bonded.

[Example 12]
A molded body was obtained in the same manner as in Example 11 except that the unidirectional material (MXD nylon) was attached to the upper and lower layers in 16 layers. The bending property was evaluated about the obtained molded object using the above-mentioned method.

[Example 13]
A molded body was obtained in the same manner as in Example 11 except that the unidirectional material (MXD nylon) was attached to upper and lower 32 layers. The bending property was evaluated about the obtained molded object using the above-mentioned method.

[Example 14]
Using the random mat base material (nylon 6) Vf 40% obtained in Reference Example 2 as the core material and the unidirectional material (MXD nylon, nylon 6 blend ratio 20:80) Vf 50% obtained in Reference Example 10 as the skin material, A molded body was obtained in the same manner as in Example 1. The bending property was evaluated about the obtained molded object using the above-mentioned method.

[Example 15]
A molded body was obtained in the same manner as in Example 14 except that the unidirectional material (MXD nylon, nylon 6 blend ratio 80:20) Vf 50% obtained in Reference Example 11 was used as the skin material. The bending property was evaluated about the obtained molded object using the above-mentioned method.

[Comparative Example 1]
In the same manner as in Example 1, using the random mat base material (nylon 6) Vf 40% obtained in Reference Example 2 as the core material and the unidirectional material (nylon 6T) Vf 50% obtained in Reference Example 9 as the skin material. A molded body was obtained. The bending property was evaluated about the obtained molded object using the above-mentioned method.

[Comparative Example 2]
Ten random mat substrates (nylon 6) Vf 40% obtained in Reference Example 2 were overlapped. A press apparatus heated to 300 ° C. was heated at 2.0 MPa for 5 minutes to obtain a molded product having t = about 2.00 mm. The bending property was evaluated about the obtained molded object using the above-mentioned method.

[Comparative Example 3]
Using the random mat substrate (nylon 66) Vf 40% obtained in Reference Example 3, a molded product was obtained in the same manner as in Comparative Example 2. The bending property was evaluated about the obtained molded object using the above-mentioned method.

The results of Examples 1 to 15 and Comparative Examples 1 to 3 are shown in Table 1.

[Example 16]
The random mat substrate (nylon 6) Vf 40% obtained in Reference Example 2 was used as the core material, and the unidirectional material (MXD nylon) Vf 50% obtained in Reference Example 6 was used as the skin material. First, a random mat substrate (nylon 6) was cut into a size of 50 cm in width and 50 cm in length, and 10 sheets were stacked. Four layers of the above-mentioned unidirectional material were bonded to both sides. At the time of bonding, a soldering iron heated to 300 ° C. was used to weld and fix the resin. The thicknesses of the respective materials are 0.08 mm, 2.00 mm, and 0.08 mm for the unidirectional material (upper surface side), the random mat base material, and the unidirectional material (lower surface side), respectively. A press apparatus heated to 300 ° C. was heated at 2.0 MPa for 5 minutes to obtain a molded article having t = 2.16 mm. The obtained sandwich plate is preheated to 240 ° C. in an infrared oven, and adjusted to a mold temperature of 80 ° C., and is placed along a pair of upper and lower molds having the cross-sectional shape of the product shown in FIG. Then, the molded product having a thickness of 2.16 mm was taken out. The molded article was free from material cracking and wrinkling, and a good carbon fiber composite material molded body could be obtained.

Claims (4)

It is composed of a reinforcing fiber having a fiber length of 10 to 100 mm and a thermoplastic resin (A), the abundance of the thermoplastic resin (A) is 10 to 1000 parts by weight with respect to 100 parts by weight of the reinforcing fiber, and the reinforcing fiber is substantially A random mat base material randomly oriented two-dimensionally,
A unidirectional material obtained by impregnating a thermoplastic resin (B) containing a semi-aromatic polyamide into reinforcing fibers provided on at least one surface of the random mat base material and aligned in one direction;
A composite material consisting of   The composite material according to claim 1, wherein the thermoplastic resin (A) contains at least one selected from the group consisting of aliphatic polyamides and semi-aromatic polyamides.   The composite material according to claim 1 or 2, wherein the semi-aromatic polyamide in the thermoplastic resin (B) is at least one selected from the group consisting of MXD nylon and 6T nylon.   The composite material according to claim 1, which is obtained by press molding.

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