JP2017119432A - Method for producing fiber-reinforced plastic and fiber-reinforced plastic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a fiber-reinforced plastic having high dynamic characteristics and high productivity when a complicated shape is molded.SOLUTION: A method for producing a fiber-reinforced plastic includes: arranging a prepreg laminate a and a prepreg laminate b obtained by laminating a plurality of prepregs formed by impregnating at least a part of a reinforced fiber having a fiber length L of 10-300 nm with a resin at predetermined positions in both of surface molds; applying a surface pressure to the prepreg laminate a and the prepreg laminate b and flowing the prepreg laminates to form a region (hereinafter referred to as mixed region c) where both of the prepreg laminate a and the prepreg laminate b exist; solidifying the respective prepreg laminates; forming the prepreg laminate a into a fiber-reinforced plastic A, forming the prepreg laminate b into a fiber-reinforced plastic B, and forming the mixed region c into a fiber-reinforced plastic C; and thereby producing a fiber-reinforced plastic where the fiber-reinforced plastic A and the fiber-reinforced plastic B are joined to each other through the fiber-reinforced plastic C.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fiber-reinforced plastic having good productivity and high mechanical properties.

  Fiber reinforced plastics composed of reinforced fibers and resins are attracting attention in industrial applications because they have high specific strength, high specific modulus, excellent mechanical properties, and high functional properties such as weather resistance and chemical resistance. Deployed in structural applications such as aircraft, spacecraft, automobiles, railways, ships, electrical appliances, sports, etc., the demand is increasing year by year.

  There are various production methods for producing fiber-reinforced plastics. For example, a production method using a prepreg obtained by impregnating a reinforced fiber with an uncured resin is known. There are various types of prepregs, for example, SMC (sheet molding compound) is known for its good productivity. SMC is a sheet base material in which fiber bundles in which thousands of reinforcing fibers having a fiber length of about several mm to several tens of mm impregnated with uncured resin are bundled in the same direction are randomly dispersed. When combined with a fast-curing resin, a complicated shape can be formed in units of several minutes (for example, Patent Document 1). However, the fiber reinforced plastic manufactured by SMC has a problem that mechanical properties are often insufficient as a structural member because the length of the reinforcing fiber is short and the content is low.

  As a method for molding a fiber reinforced plastic having high mechanical properties, a molding method using a prepreg (unidirectional prepreg) in which reinforcing fibers are oriented in one direction and impregnated with a resin is known. By making the reinforcing fibers unidirectional, the volume content of the reinforcing fibers can be made higher than that of the SMC, and the waviness of the reinforcing fibers can be reduced, so that a fiber-reinforced plastic having high mechanical properties can be obtained. As a method of forming a complicated shape using a unidirectional prepreg, for example, a unidirectional prepreg impregnated with a thermosetting resin is laminated by hand along the mold one by one to form a preform, and the preform is formed by autoclave molding. There is a method of solidifying by using heating / pressurizing means such as press molding (for example, Patent Document 2). Thereby, a high-quality fiber reinforced plastic having high mechanical properties can be obtained.

JP-A-1-163218 JP-A-8-25491

  However, a method of producing a fiber-reinforced plastic by curing a preform formed by hand-setting a unidirectional prepreg is poor in productivity and is not suitable for mass production of fiber-reinforced plastic.

  Accordingly, an object of the present invention is to provide a method for producing a fiber-reinforced plastic having excellent mechanical properties and complex shapes and exhibiting high mechanical properties with high productivity. Further, the present invention provides a fiber reinforced plastic having high mechanical properties while having a complicated shape.

In order to solve this problem, the present invention provides the following fiber-reinforced plastic manufacturing method and fiber-reinforced plastic.
1) A prepreg laminate a and a prepreg laminate b obtained by laminating a plurality of prepregs in which a resin is impregnated with a reinforced fiber having a fiber length L of 10 to 300 mm at least in part are provided in a predetermined type in a double-sided mold. After being disposed at a position and flowing by applying a surface pressure to the prepreg laminate a and the prepreg laminate b to form a region where both the prepreg laminate a and the prepreg laminate b exist (hereinafter referred to as a mixed region c), By solidifying each, the prepreg laminate a is made of fiber reinforced plastic A, the prepreg laminate b is made of fiber reinforced plastic B, and the mixed region c is made of fiber reinforced plastic C, so that the fiber reinforced plastic A and the fiber reinforced plastic B are A method for producing a fiber reinforced plastic, which is a fiber reinforced plastic joined via a fiber reinforced plastic C.
2) Fiber reinforced plastic A and fiber reinforced plastic B are fiber reinforced plastics joined via fiber reinforced plastic C, where fiber reinforced plastic A, fiber reinforced plastic B, and fiber reinforced plastic C are reinforced fiber volumes. The content rate is 40% to 65%, and at least a part of the reinforcing fibers are divided into the fiber length L = 10 to 300 mm. The fiber reinforced plastic A and the fiber reinforced plastic B are substantially reinforced fibers. Is a fiber reinforced plastic in which a plurality of layers oriented in one direction are laminated, and there are reinforced fibers that straddle fiber reinforced plastic A and fiber reinforced plastic C, and reinforced fibers that straddle fiber reinforced plastic B and fiber reinforced plastic C. Yes, fiber reinforced plastic.

  According to the present invention, a fiber reinforced plastic having a complicated shape and excellent mechanical properties can be produced and provided with high productivity.

It is a conceptual diagram which shows an example of the cross section of the fiber reinforced plastics in this invention. It is a conceptual diagram which shows an example of the manufacturing method of the fiber reinforced plastic in this invention. It is a conceptual diagram which shows an example of the manufacturing method of the fiber reinforced plastic in this invention. It is a conceptual diagram which shows an example of the cross section of the fiber reinforced plastics in this invention. 1 is a diagram illustrating an integral molding method described in Example 1. FIG. 6 is a diagram illustrating an integral molding method described in Example 2. FIG. 6 is a diagram illustrating an integral molding method described in Example 3. FIG. It is a figure which shows the shape made into a shaping | molding object in Examples 4-6.

  In order to provide a method for producing a fiber-reinforced plastic having a complex shape having excellent mechanical properties composed of reinforcing fibers and a resin with high productivity, at least a part of the fiber length L is 10 to 300 mm. A prepreg laminate a and a prepreg laminate b obtained by laminating a plurality of prepregs in which a reinforced fiber is impregnated with a resin are arranged at predetermined positions in a double-sided mold, and the prepreg laminate a and the prepreg laminate b To form a region where both the prepreg laminate a and the prepreg laminate b are present (hereinafter referred to as a mixed region c), and then solidify each of the prepreg laminate a to fiber-reinforced plastic. A, the prepreg laminate b is made of fiber reinforced plastic B, and the mixed region c is made of fiber reinforced plastic C, thereby solving such a problem.

  By using a prepreg impregnated with a resin in advance, a fiber-reinforced plastic having a high volume content of reinforcing fibers can be produced, and high mechanical properties can be exhibited. When manufacturing fiber-reinforced plastics with complex shapes, if the manufacturing method does not allow joints, it is necessary to accurately cut out the prepreg laminate and place it in the mold, but join the mixed regions of the prepreg laminates By allowing it as a part, it is easy to handle the prepreg laminate, and the prepreg can be cut into a size and shape with a good yield to produce a fiber-reinforced plastic with high productivity.

  In the production method of the present invention, the prepreg laminates a and b are arranged at predetermined positions in the double-sided mold, and when the prepreg laminate a and the prepreg laminate b are subjected to surface pressure, the laminates flow. Thus, it is important to form a region (mixed region) where both the prepreg laminate a and the prepreg laminate b are mixed. Each prepreg constituting the prepreg laminate a and the prepreg laminate b has a fiber length of at least a part of the reinforcing fibers in order to give the prepreg laminate a and the prepreg laminate b a property of flowing by surface pressure. L is preferably 10 to 300 mm. More preferably, the fiber length L of 50 to 100% of the reinforcing fibers contained in the prepreg laminate a and the prepreg laminate b is 10 to 300 mm, and particularly preferably the reinforcement included in both prepreg laminates. The fiber length L of 50 to 100% of the fibers is 15 to 100 mm.

  The prepreg laminate a and the prepreg laminate b may be a laminate obtained by laminating a plurality of prepregs having different thicknesses and volume contents of reinforcing fibers, and the prepreg laminate a and the prepreg laminate b may be reinforced. The fiber and resin may be different. The prepreg in the prepreg laminate may be a unidirectional prepreg in which reinforcing fibers are unidirectionally oriented, SMC in which reinforcing fibers are randomly oriented, or a laminate thereof. In the case of a unidirectional prepreg, it may be a laminate in which a plurality of prepregs having different fiber directions of the reinforcing fibers are laminated. Usually, when integrally molding using a unidirectional prepreg in which continuous reinforcing fibers are arranged in one direction, there is a method in which the prepreg laminate a and the prepreg laminate b are stacked and simultaneously pressed and solidified. Since the fiber does not flow in the fiber direction, a mixed region of the prepreg laminate a and the prepreg laminate b cannot be formed, and the strength of the joint portion is reduced, so that it is not suitable for integral molding. In the present invention, by including discontinuous reinforcing fibers that can flow into the prepreg laminate, the prepreg laminate can be flowed to form a mixed region c, and when solidified, the fiber reinforced plastic A and fibers Since the reinforced plastic C and the reinforced fiber straddling the fiber reinforced plastic B and the fiber reinforced plastic C exist, the strength of the joint portion is improved. Examples of the prepreg that includes discontinuous reinforcing fibers and in which the reinforcing fibers are oriented in one direction include a cut prepreg as described later, and a material in which recycled fibers are oriented in one direction and impregnated with a resin.

  The reinforcing fiber used in the present invention is not particularly limited, and may be glass fiber, Kevlar fiber, carbon fiber, graphite fiber, boron fiber, or the like. Among these, carbon fiber is preferable from the viewpoint of specific strength and specific modulus.

  The resin impregnated into the reinforcing fiber is not particularly limited, and may be a thermoplastic resin or a thermosetting resin. Examples of the thermoplastic resin include polyamide (PA), polyacetal, polyacrylate, polysulfone, ABS, polyester, acrylic, polybutylene terephthalate (PBT), polycarbonate (PC), polyethylene terephthalate (PET), polyethylene, polypropylene, Examples thereof include polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyether imide (PEI), polyether ketone ketone (PEKK), liquid crystal polymer, vinyl chloride, fluorine resins such as polytetrafluoroethylene, and silicone. Examples of the thermosetting resin include unsaturated polyester resins, vinyl ester resins, epoxy resins, benzoxazine resins, phenol resins, urea resins, melamine resins, and polyimide resins. Deformation of these resins and resins of two or more blends can also be used. Further, these thermosetting resins may be resins that are self-cured by heat, or may include a curing agent, a curing accelerator, and the like. A filler or the like may be mixed for the purpose of improving heat resistance and mechanical properties.

  At least one of the prepreg laminated body a and the prepreg laminated body b has a fiber length L = 10 by inserting a plurality of cuts into a prepreg in which reinforcing fibers are substantially oriented in one direction. It is preferable that it is a prepreg laminated body containing the cut prepreg parted to -300 mm. By cutting into a prepreg in which the reinforcing fibers are oriented in one direction and dividing the reinforcing fibers into fiber length L = 10 to 300 mm, the volume content of the reinforcing fibers is high, and the reinforcing fibers are oriented in one direction. Thus, a fiber-reinforced plastic having high mechanical properties is obtained when solidified, and a cut prepreg having fluidity in the fiber direction of the reinforcing fiber can be obtained when a surface pressure is applied. Although all the reinforcing fibers may be cut by cutting or may leave a reinforcing fiber that is not partially cut, 80% or more of the reinforcing fibers included in the prepreg may be cut by cutting. It is preferable from the viewpoint of fluidity. Usually, a prepreg having reinforcing fibers oriented in one direction has a high fluidity in a direction close to the direction perpendicular to the fibers, and therefore, a prepreg containing reinforcing fibers oriented at 80 to 100 ° with respect to the flow direction is notched. Need not be inserted. More preferably, the fiber length L of the reinforcing fiber is 15 to 100 mm, and more preferably 15 to 30 mm. By including such a cut prepreg in the prepreg laminate a or the prepreg laminate b, the mechanical properties of the fiber reinforced plastic obtained by solidifying the prepreg laminate a and the prepreg laminate b by integral molding by the manufacturing method of the present invention are as follows: It will be excellent. Both the prepreg laminate a and the prepreg laminate b preferably include a cut prepreg. More preferably, it is a prepreg laminate in which the number of cut prepregs is 50 to 100% when the total number of prepregs in the prepreg laminate a is 100%, and the same applies to the prepreg laminate b. Note that that the reinforcing fibers are substantially oriented in one direction means that 90% or more of the reinforcing fibers are within ± 10 ° with respect to the average orientation angle in the fiber direction of all the reinforcing fibers (the same applies hereinafter). .

  There is no limitation on the method of inserting a notch into the prepreg to obtain a notched prepreg, and a method using a blade or a method using a laser may be used. There is no limitation also in the pattern of a notch, and it may be an angle with respect to the fiber direction of a reinforced fiber, and each notch may be curvilinear or linear.

  As an arrangement method when the prepreg laminate a and the prepreg laminate b are arranged at predetermined positions in the double-sided mold, the prepreg laminates may be partially overlapped. In the case of a partial overlap, when the surface pressure is applied, the prepreg laminate flows to form a tapered mixed region c, and when solidified, the fiber reinforced plastic A and the fiber reinforced plastic as shown in FIG. B becomes a fiber reinforced plastic joined in a taper shape in the fiber reinforced plastic C, and can be integrally formed with a joint portion having high mechanical properties.

  In the present invention, even if the prepregs are not intertwined in a complicated manner, the fiber reinforced plastic including the joint portion tapered by the flow is also regarded as the fiber reinforced plastic C in which the mixed region c of the prepreg laminate a and the prepreg laminate b is cured. . The tapered joint surface efficiently transmits the load generated between the fiber reinforced plastic A and the fiber reinforced plastic B, and thus exhibits high joint strength.

  FIG. 1 shows a cross section perpendicular to the surface of the fiber reinforced plastic C of the fiber reinforced plastic including the fiber reinforced plastic A, the fiber reinforced plastic B, and the fiber reinforced plastic C. In FIG. 1, a point where a layer continuous from the fiber reinforced plastic A and one surface of the fiber reinforced plastic C intersect is defined as an intersection point P, and a layer continuous from the fiber reinforced plastic B and the other surface of the fiber reinforced plastic C intersect. Assuming the intersection point Q, the length of the prepreg laminate a and the prepreg laminate b to be stacked is either the angle θ shown in FIG. 1, that is, the line segment 1 connecting the intersection point P and the intersection point Q and the fiber reinforced plastic C. It is preferable to overlap so that the angle formed with the surface of the film becomes smaller than 30 °. That is, it is preferable that the prepreg laminated body a and the prepreg laminated body b are stacked at least twice as thick as the thicker one. More preferably, it is at least four times the thickness of the thicker one of the prepreg laminate a and the prepreg laminate b. By adopting a tapered joint structure in which θ is smaller than 30 °, when a tensile or bending load is applied to the fiber reinforced plastic having the cross section of FIG. The area where stress is transmitted by the continuous layer from the plastic B increases, and high bonding strength is exhibited. From the viewpoint of productivity, θ is preferably as small as possible. However, in practice, in order to make θ smaller than 1 °, it is necessary to greatly increase the surface pressure and the area where the prepreg laminates are stacked. It is not preferable. Accordingly, the length of the prepreg laminate a and the prepreg laminate b that are stacked is preferably 50 times or less the thicker of the prepreg laminate a and the prepreg laminate b.

  As another arrangement method when the prepreg laminate a and the prepreg laminate b are arranged at predetermined positions in the double-sided mold, the prepreg laminate a and the prepreg laminate b are arranged separately as shown in FIG. Also good. In order to mold into a complicated shape, a mold that is difficult to place the prepreg laminate may be used. Even in such a case, the prepreg laminate is placed in a place where the prepreg laminate is easy to place, and the prepreg laminate is obtained by surface pressure. Can be made to flow to form a mixed region c between the prepreg laminates. The distance between the prepreg laminate a and the prepreg laminate b depends on the surface pressure and the thickness of the prepreg laminate, but if it is too far, the flowing prepreg laminate forms a mixed region c without contact. If the two prepreg laminates contact each other before flowing, the flow is hindered and the mixed region c may not be formed. The flow distance of the prepreg laminate depends on the area of the prepreg laminate, and if the size (charge rate) of the prepreg laminate before flow is 50 to 95% with respect to the target size after molding, Good flow is obtained, and the mixed region c can be formed. A more preferable charge rate is 60 to 80%.

  When the prepreg laminate a and the prepreg laminate b are arranged separately and integrally formed, the angle formed by the surface in contact with the prepreg laminate b in the prepreg laminate a and the flow direction of the prepreg laminate a is 75. It is preferable that the angle between the surface in contact with the prepreg laminate a in the prepreg laminate b and the flow direction of the prepreg laminate b is 75 ° or less. In FIG. 2, the prepreg laminate a flows in the flow direction 3, the surface where the prepreg laminate a contacts the prepreg laminate b is a surface 5, and the flow direction 3 and the surface 5 form an angle 7. The prepreg laminate b flows in the flow direction 4, the surface where the prepreg laminate b contacts the prepreg laminate a is a surface 6, and the flow direction 4 and the surface 6 form an angle 8. When both the corner 7 and the corner 8 exceed 75 °, the progress of the flow is hindered on the surface where both the prepreg laminates are in contact, and the angle of the reinforcing fiber is easily flowed to an angle close to 90 ° with respect to the flow direction, and solidified. In such a case, the fiber reinforced plastic C tends to break, which is not preferable. Therefore, it is preferable that the angle 7 and / or the angle 8 is 75 ° or less. Preferably, both the corners 7 and 8 are 75 ° or less, and more preferably both are 60 ° or less. By reducing the angle, the reinforcing fiber flows without counteracting the flow, and the fiber-reinforced plastic C having high mechanical properties is obtained. Note that the flow direction 3 and the flow direction 4 and the surface 5 and the surface 6 do not need to be parallel, and the corners 7 and 8 need not have the same size. Note that the lower limit value of the angles 7 and 8 that can be achieved realistically is 10 °. When the corners 7 and 8 are less than 10 °, it may be difficult to prepare a prepreg laminate having such surfaces 5 or 6.

  In a preferred embodiment of the prepreg laminate in the present invention, at least one of the prepreg laminate a and the prepreg laminate b is a prepreg laminate including a prepreg in which reinforcing fibers are randomly oriented. The prepreg in which the reinforcing fibers are randomly oriented is, for example, SMC. When the shape of the target fiber reinforced plastic is complicated, it is effective to use a base material that emphasizes fluidity, that is, a prepreg laminate including a prepreg in which reinforcing fibers are randomly oriented such as SMC. It becomes a manufacturing means.

  More preferably, as shown in FIG. 3, at least one of the prepreg laminate a and the prepreg laminate b is a prepreg (unidirectional prepreg) laminate in which the reinforcing fibers are oriented in one direction, and the reinforcing fibers are randomly oriented. It is mentioned that it is a prepreg laminated body which laminated | stacked the prepreg. More preferably, both the prepreg laminate a and the prepreg laminate b are a prepreg laminate in which a laminate of prepregs (unidirectional prepreg) in which reinforcing fibers are oriented in one direction and a prepreg in which reinforcing fibers are randomly oriented are laminated. Is the body. The prepreg in which the unidirectional reinforcing fibers are oriented in one direction may be the above-described cut prepreg. A prepreg in which reinforcing fibers are randomly oriented generally has lower mechanical properties than a unidirectional prepreg because the reinforcing fiber content is generally low. Therefore, in order to manufacture a fiber reinforced plastic having a complex shape with high productivity while utilizing the mechanical characteristics of the unidirectional prepreg, it is preferable to maintain rigidity with the unidirectional prepreg having a joint and to form the complex shape by SMC. .

  The prepreg laminate a and the prepreg laminate b are prepregs in which the reinforcing fibers are oriented in one direction instead of the prepreg 10 in which the reinforcing fibers in FIG. 3 are randomly oriented, and at least some of the reinforcing fibers are 10 to 15 mm. The laminate may be a prepreg laminate laminated on a unidirectional prepreg laminate. At this time, it is preferable that the length of the reinforcing fiber in the laminated body 9 of the unidirectional prepreg is 15 to 300 mm in order to emphasize the mechanical characteristics. That is, at least one of the prepreg laminate a and the prepreg laminate b is such that the reinforcing fibers are oriented in one direction, at least a part of the reinforcing fibers is a prepreg laminate of 15 to 300 mm, and the reinforcing fibers are oriented in one direction. A prepreg laminate in which at least some of the reinforcing fibers are laminated with a prepreg laminate of 10 to 15 mm may be used. The one-way prepreg may be the above-described cut prepreg.

  The discontinuous reinforcing fibers contained in the unidirectional prepreg exhibit a higher fluidity as the fiber length is shorter, and particularly show a remarkable fluidity when the fiber length is shorter than 15 mm. Therefore, it is effective to use a unidirectional prepreg having a relatively short fiber length in order to fill a portion having a complicated shape and cannot be followed by a unidirectional prepreg having high mechanical characteristics. Even when the fiber length is shorter than 15 mm, the reinforced fibers are aligned in one direction, so that the fiber content is high, and even when molded into a complicated shape, a fiber reinforced plastic having a high fiber content everywhere is manufactured. It is possible.

  When a prepreg in which reinforcing fibers are randomly oriented or a prepreg having at least a part of reinforcing fibers of 10 to 15 mm is a good flow prepreg, a prepreg laminate in which a good flow prepreg and a unidirectional prepreg are laminated on a prepreg laminate a or a prepreg laminate b When the body is used, a mixed region of the unidirectional prepreg and the good flow prepreg included in the prepreg laminate a or the prepreg laminate b, a mixed region of the unidirectional prepregs, and a mixed region of the good flow prepregs are generated. All are considered as mixed region c, and are regarded as fiber reinforced plastic C after curing.

  The fiber reinforced plastic obtained in the present invention is manufactured with high productivity by integrally forming complex shapes by connecting preforms arranged in a relatively simple shape with joints that straddle reinforcing fibers during molding. It has been done. That is, fiber reinforced plastic A and fiber reinforced plastic B are fiber reinforced plastics joined via fiber reinforced plastic C, and fiber reinforced plastic A, fiber reinforced plastic B, and fiber reinforced plastic C are reinforced fiber volumes. The content rate is in the range of 40 to 65%, and at least a part of the reinforcing fibers are divided into the fiber length L = 10 to 300 mm, and the fiber reinforced plastic A and the fiber reinforced plastic B are: A fiber reinforced plastic in which a plurality of layers in which reinforced fibers are substantially oriented in one direction are laminated, and includes a reinforced fiber that straddles fiber reinforced plastic A and fiber reinforced plastic C, and fiber reinforced plastic B and fiber reinforced plastic C. It is a fiber-reinforced plastic with striking reinforcing fibers.

  FIG. 4 shows a fiber reinforced plastic according to the present invention, in which fiber reinforced plastic A and fiber reinforced plastic B are joined together via fiber reinforced plastic C, and reinforced fiber 11 straddling fiber reinforced plastic A and fiber reinforced plastic C. It is the conceptual diagram which showed the cross section of the fiber reinforced plastic in which the reinforced fiber 12 which straddles the fiber reinforced plastic B and the fiber reinforced plastic C exists.

  The fiber reinforced plastic A, fiber reinforced plastic B, and fiber reinforced plastic C preferably have a volume content of the reinforced fiber of 40% or more in order to exhibit excellent mechanical properties such as elastic modulus and strength. When the volume content of the reinforcing fibers is larger than 65%, the reinforcing fibers are too tightly packed and cracks along the reinforcing fibers are likely to occur. Therefore, the volume content of the reinforcing fibers is preferably 65% or less. Accordingly, the volume content of the reinforcing fibers of the fiber reinforced plastic A, the fiber reinforced plastic B, and the fiber reinforced plastic C is preferably in the range of 40 to 65%. A particularly preferable volume content range of the reinforcing fibers is in the range of 45 to 60%.

The fiber reinforced plastic A and the fiber reinforced plastic B preferably have a laminated structure in which a plurality of layers in which reinforcing fibers are substantially oriented in one direction are laminated. For example, in FIG. 1, fiber reinforced plastic A and fiber reinforced plastic B are fiber reinforced layers in which a layer 3 in which the fiber direction of the reinforced fiber is oriented in the transverse direction and a layer 4 in which the fiber direction of the reinforced fiber is oriented in the depth direction are laminated. It is plastic. When the reinforcing fibers are oriented in one direction, the reinforcing fibers are densely packed, and it becomes easier to achieve the volume content of the reinforcing fibers, thereby improving the mechanical properties.
In addition, the fiber reinforced plastic A and the fiber reinforced plastic B can be loaded in various directions within the surface of the fiber reinforced plastic by forming a laminated structure in which a plurality of layers in which the reinforced fibers are substantially oriented in one direction are stacked. It can be designed to withstand the structure.

  The thickness, the number of layers and the layer configuration of the fiber reinforced plastic A and the fiber reinforced plastic B may be different, and the types of the reinforced fiber and the resin may be different. Are preferably the same kind of resin.

  Regarding the lengths of the reinforcing fibers in the fiber reinforced plastic A, the fiber reinforced plastic B, and the fiber reinforced plastic C, it is preferable that at least a part of the reinforcing fibers is divided within a range of the fiber length L = 10 to 300 mm. When all the reinforcing fibers are continuous, when molded into a fiber reinforced plastic with a complicated shape, the reinforcing fibers are difficult to follow the corners, and sink marks or resin due to insufficient resin may be squeezed out and the resin may be rich. . A more preferable fiber length L of the reinforcing fibers is 15 to 100 mm. More preferably, it is a fiber reinforced plastic in which the fiber length L of 50 to 100% of the reinforced fibers contained in the fiber reinforced plastic A, fiber reinforced plastic B, and fiber reinforced plastic C is 15 to 100 mm.

  The fiber reinforced plastic C preferably has a laminated structure, but may not have a laminated structure. Like the reinforcing fiber 11 and the reinforcing fiber 12 in FIG. 4, the fiber reinforced plastic A and the fiber reinforced plastic B are firmly joined by the fiber reinforced plastic C due to the presence of the reinforced fiber that straddles the fiber reinforced plastic. In the present invention, the fiber length and the number of the reinforcing fibers spanning the fiber reinforced plastic A and the fiber reinforced plastic C or the fiber reinforced plastic B and the fiber reinforced plastic C, such as the reinforced fiber 11 and the reinforced fiber 12, are not particularly limited. The reinforcing fiber that straddles the fiber-reinforced plastic has a long fiber length and is preferably as many as possible. The fiber reinforced plastic A or the fiber reinforced plastic B may straddle the fiber reinforced plastic C with each layer.

  In the fiber reinforced plastic according to the present invention, when a plurality of sheet-like base materials composed of reinforced fibers and a resin are integrally formed, a region holding a layer structure with less disturbance is formed in the fiber reinforced plastic A and the fiber reinforced plastic. A region where the fiber reinforced plastic A and the fiber reinforced plastic B are mixed between the plastic B and the fiber reinforced plastic A is defined as a fiber reinforced plastic C. Further, the fiber reinforced plastic A, the fiber reinforced plastic B, and the fiber reinforced plastic C are not necessarily arranged in series. As shown in FIG. 4 (a), the fiber reinforced plastic A and the fiber reinforced plastic B may form a step through the fiber reinforced plastic C. As shown in FIG. 4 (b), the fiber reinforced plastic A, The fiber reinforced plastic B and the fiber reinforced plastic C may be curved.

  In the present invention, the preferred fiber-reinforced plastic structure includes fiber-reinforced plastic A, fiber-reinforced plastic B, and fiber-reinforced plastic C as shown in FIG. There is substantially no resin layer at the site where the continuous layer from plastic A and the continuous layer from fiber reinforced plastic B are in contact, and the continuous layer from fiber reinforced plastic A and one surface of fiber reinforced plastic C intersect. When the point where the point where the point is the intersection point P and the point where the layer continuous from the fiber reinforced plastic B and the other surface of the fiber reinforced plastic C intersect is the intersection point Q, the line segment connecting the intersection point P and the intersection point Q, and the fiber reinforced plastic Examples thereof include fiber reinforced plastics having an angle formed with any surface of C smaller than 30 °.

  Within the fiber reinforced plastic C, both the fiber reinforced plastic A and the fiber reinforced plastic B are defined as regions where the thickness gradually decreases and overlaps while forming a taper. The reinforcing fibers straddling the fiber reinforced plastic B and the fiber reinforced plastic C are present in a continuous layer from the fiber reinforced plastic A and the fiber reinforced plastic B, respectively. A portion where the fiber reinforced plastic A and the fiber reinforced plastic B are in contact with each other in the cross section of the fiber reinforced plastic C in FIG. Since the resin layer is not included in the curve 2, the stress is efficiently transmitted between the fiber reinforced plastic A and the continuous layer of the fiber reinforced plastic B, and the mechanical properties of the integrally formed fiber reinforced plastic are improved. Therefore, it is preferable that the resin layer is not substantially present at a portion where the layer continuous from the fiber reinforced plastic A and the layer continuous from the fiber reinforced plastic B are in contact with each other. Here, the phrase “substantially no resin layer” means that there is no continuous layer composed only of a resin having a thickness greater than 100 μm.

  In FIG. 1, a point where a layer continuous from the fiber reinforced plastic A and one surface of the fiber reinforced plastic C intersect is defined as an intersection point P, and a layer continuous from the fiber reinforced plastic B and the other surface of the fiber reinforced plastic C intersect. The line segment connecting the intersection points Q is the line segment 1, and the angle θ between the line segment 1 and one surface of the fiber reinforced plastic C is preferably smaller than 30 °. By adopting a tapered joint structure in which the angle θ is smaller than 30 °, when a tensile or bending load is applied to the fiber reinforced plastic having the cross section of FIG. The area in which the continuous layer from the reinforced plastic B transmits stress increases, and the bonding strength is obtained. Accordingly, by making the angle θ smaller than 30 °, the fiber reinforced plastic having the cross section of FIG. 1 has high mechanical properties. More preferably, the angle θ is 20 ° or less, and more preferably, the angles formed by both the surface of the line segment 1 and the fiber reinforced plastic C are both 20 ° or less. Note that the lower limit of the angle formed between the line segment 1 and one of the surfaces of the fiber reinforced plastic C is not particularly limited, but the lower limit of the angle θ that can be practically achieved is 1 °.

  The fiber reinforced plastic of the present invention has a fiber reinforced plastic in which the volume content of the reinforced fiber is lower than 40% and the reinforcing fibers are randomly oriented, or a coating layer such as a resin layer, as necessary. It may be adhered to a plastic surface.

EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to the invention as described in an Example. The prepreg used in this example is “Torayca” (registered trademark) prepreg sheet P3052S-15 (reinforced fiber: T700S, thermosetting resin: 2500, volume content of reinforced fiber: 58%), and the reinforced fiber is substantially Are oriented in one direction. A notch was inserted into the prepreg using a blade, and a cut prepreg in which the reinforcing fibers were divided so that substantially all the reinforcing fibers had a fiber length of 24 mm was obtained. The cuts were straight, the length of each cut projected onto the side perpendicular to the reinforcing fibers was 1.0 mm, and the angle between the cut and the fiber direction of the reinforcing fibers was 14 °. The direction of the reinforcing fiber of the cut prepreg is set to 0 °, and laminated to [+ 45 ° / 0 ° / −45 ° / 90 °] _2s (thickness 2.4 mm), and as shown in FIGS. In the lower mold 14 having a frame of 100 mm, the prepreg laminate a and the prepreg laminate b are prepared so that the total area of the prepreg laminate before molding is 8000 mm ² , and the mold is heated to 130 ° C. It arrange | positioned so that a flow direction might become a 0 degree direction.

  Thereafter, a surface pressure of 3 MPa is applied using the upper mold 13 to cause both the prepreg laminates to flow to form a mixed region c where both the prepreg laminate a and the prepreg laminate b exist, and hold and solidify for 1 hour. The prepreg laminate a is fiber reinforced plastic A, the prepreg laminate b is fiber reinforced plastic B, the mixed region c is fiber reinforced plastic C, and the fiber reinforced plastic A and the fiber reinforced plastic B are joined via the fiber reinforced plastic C. Manufactured fiber reinforced plastic. A test piece of 15 mm × 100 mm is cut out from the fiber reinforced plastic so that the 0 ° direction is the longitudinal direction, and the span length is 80 mm according to JIS K 7074 (2008) so that the fiber reinforced plastic C comes to the center. A bending test was performed to obtain the bending strength.

Example 1
As shown in FIG. 5, the prepreg laminate a and the prepreg laminate b were both made into a 40 mm × 100 mm prepreg laminate, and 10 mm overlapped and integrally molded to obtain a fiber reinforced plastic. When the cross section perpendicular to the flow direction and the surface of the fiber reinforced plastic was confirmed, the fiber reinforced plastic A and the fiber reinforced plastic B having a laminated structure and the fiber reinforced plastic C having a tapered cross sectional structure as shown in FIG. It could be confirmed. The resin layer did not exist in the part which the layer continuous from the fiber reinforced plastic A and the layer continuous from the fiber reinforced plastic B contact. The angle corresponding to the angle θ was 15 °. The three point bending strength was 450 MPa.

(Example 2)
As shown in FIG. 6, the prepreg laminate a and the prepreg laminate b were both 40 mm × 100 mm prepreg laminates, arranged 20 mm apart, and integrally molded. When the cross section was observed, a fiber reinforced plastic C in which both were mixed was found between the fiber reinforced plastic A and the fiber reinforced plastic B having a laminated structure, and the fiber reinforced plastic A, the fiber reinforced plastic C, and the fiber reinforced plastic B were mixed. Reinforcing fibers across the fiber reinforced plastic C were confirmed. The three point bending strength was 90 MPa.

(Example 3)
As shown in FIG. 7, the angle formed by the flow direction with the surface where the prepreg laminate a and the prepreg laminate b are in contact with each other was 45 °, and the prepreg laminate a and the prepreg laminate b were arranged 20 mm apart and integrally molded. When the cross section was observed, a fiber reinforced plastic C in which both were mixed was found between the fiber reinforced plastic A and the fiber reinforced plastic B having a laminated structure, and the fiber reinforced plastic A, the fiber reinforced plastic C, and the fiber reinforced plastic B were mixed. Reinforcing fibers across the fiber reinforced plastic C were confirmed. The three point bending strength was 310 MPa.

(Comparative Example 1)
A prepreg laminate a and a prepreg laminate b were prepared in a size of 50 mm × 100 mm, and were integrally molded in the same manner as in Example 2 except that they were put in a mold without a gap to produce a fiber reinforced plastic. As a result, the base material hardly flowed and cracked when taking out the fiber reinforced plastic from the mold.

(Comparative Example 2)
Integral molding was performed under the same conditions as in Example 1 except that a prepreg without a cut was used. When the cross-section was observed, the joint location was not tapered and a resin pool was present. The three point bending strength was 50 MPa.

(Comparative Example 3)
Except that a prepreg in which all the reinforcing fibers were continuous fibers was used without any notches, it was integrally molded under the same conditions as in Example 2 to obtain bending strength. The prepreg flowed in the 90 ° layer, but the 0 ° layer did not flow, and cracked when the test piece was cut out.

Example 4
As shown in FIG. 8, integral molding was performed in the same manner as in Example 1 except that a mold for molding a shape having ribs was used. As a result, there was a portion where the reinforcing fiber did not enter into a part of the rib.

(Example 5)
As the prepreg laminate a and the prepreg laminate b, a prepreg laminate a and a prepreg laminate b in which SMC having a thickness of 1 mm was further added on the prepreg laminate a and prepreg laminate b of Example 1 were obtained. The SMC was manufactured by cutting a chopped strand of 25 mm × 3 mm from the prepreg used for producing the cut prepreg, bringing the chopped strand to 70 ° C. in a mold, and vacuuming.

  As a result of the integral molding, it was possible to produce a fiber reinforced plastic including reinforcing fibers in the ribs, including the mixed region c of the prepreg laminate a and the prepreg laminate b.

(Example 6)
As the prepreg laminate a and the prepreg laminate b, a cut prepreg in which cuts were inserted on the prepreg laminate a and prepreg laminate b of Example 1 so that all the fibers had a fiber length of 12 mm was used. A prepreg laminate a and a prepreg laminate b were added to the laminate laminated at [+ 45/0 / −45 / 90] s.

  As a result of the integral molding, it was possible to produce a fiber reinforced plastic including reinforcing fibers in the ribs, including the mixed region c of the prepreg laminate a and the prepreg laminate b.

1: Line segment connecting intersection point P and intersection point Q 2: Curve showing a cross section of a portion where fiber reinforced plastic A and fiber reinforced plastic B contact each other 3: Flow direction of prepreg laminate a 4: Flow direction 5 of prepreg laminate b : Surface 6 where the prepreg laminate a is in contact with the prepreg laminate b 6: surface where the prepreg laminate b is in contact with the prepreg laminate a 7: angle 8 formed by the flow direction 3 and the surface 5: angle 9 formed by the flow direction 4 and the surface 6 : Unidirectional prepreg laminate 10: prepreg with reinforcing fibers randomly oriented 11: reinforcing fiber straddling fiber reinforced plastic A and fiber reinforced plastic C 12: reinforcing fiber straddling fiber reinforced plastic B and fiber reinforced plastic C 13: top Mold 14: Lower mold (frame)

Claims (10)

  A prepreg laminate a and a prepreg laminate b obtained by laminating a plurality of prepregs in which a resin is impregnated with a reinforced fiber having a fiber length L of 10 to 300 mm is placed at a predetermined position in a double-sided mold. And after forming a region where both the prepreg laminate a and the prepreg laminate b are present (hereinafter referred to as a mixed region c), each of the prepreg laminate a and the prepreg laminate b is caused to flow. By solidifying, the prepreg laminate a is made of fiber reinforced plastic A, the prepreg laminate b is made of fiber reinforced plastic B, and the mixed region c is made of fiber reinforced plastic C. A method for producing a fiber reinforced plastic, which is a fiber reinforced plastic joined via plastic C.   At least one of the prepreg laminate a and the prepreg laminate b has a fiber length L = 10 by inserting a plurality of cuts into the prepreg in which the reinforcement fibers are oriented substantially in one direction. The manufacturing method of the fiber reinforced plastics of Claim 1 which is a prepreg laminated body containing the cut prepreg parted in -300mm.   The manufacturing method of the fiber reinforced plastics of Claim 1 or 2 which arrange | positions the prepreg laminated body a and the prepreg laminated body b partially overlapping.   The manufacturing method of the fiber reinforced plastics of Claim 1 or 2 which arrange | positions the prepreg laminated body a and the prepreg laminated body b apart.   The angle formed by the surface in contact with the prepreg laminate b in the prepreg laminate a and the flow direction of the prepreg laminate a is 75 ° or less and / or in contact with the prepreg laminate a in the prepreg laminate b. The manufacturing method of the fiber reinforced plastics of Claim 4 whose angle which the surface and the flow direction of the prepreg laminated body b make is 75 degrees or less.   The method for producing a fiber-reinforced plastic according to any one of claims 1 to 5, wherein at least one of the prepreg laminate a and the prepreg laminate b is a prepreg laminate including a prepreg in which reinforcing fibers are randomly oriented.   Any one of the prepreg laminated body a and the prepreg laminated body b is a prepreg laminated body in which a prepreg in which reinforcing fibers are oriented in one direction and a prepreg in which reinforcing fibers are randomly oriented are laminated. A method for producing the fiber-reinforced plastic according to claim 1.   At least one of the prepreg laminate a and the prepreg laminate b is such that the reinforcing fibers are oriented in one direction, at least some reinforcing fibers are prepregs of 15 to 300 mm, and the reinforcing fibers are oriented in one direction, and at least some The manufacturing method of the fiber reinforced plastics in any one of Claims 1-7 which is a prepreg laminated body which the reinforced fiber laminated | stacked the prepreg of 10-15 mm. Fiber reinforced plastic A and fiber reinforced plastic B are fiber reinforced plastics joined via fiber reinforced plastic C,
The fiber reinforced plastic A, the fiber reinforced plastic B, and the fiber reinforced plastic C have a volume content of reinforced fibers of 40% to 65%, and at least some of the reinforced fibers are divided into fiber lengths L = 10 to 300 mm. And
The fiber reinforced plastic A and the fiber reinforced plastic B are fiber reinforced plastics in which a plurality of layers in which reinforced fibers are substantially oriented in one direction are laminated.
A fiber-reinforced plastic in which there are reinforcing fibers that straddle fiber-reinforced plastic A and fiber-reinforced plastic C, and reinforcing fibers that straddle fiber-reinforced plastic B and fiber-reinforced plastic C. In a cross section that includes fiber reinforced plastic A, fiber reinforced plastic B, and fiber reinforced plastic C and is perpendicular to the surface of fiber reinforced plastic C,
There is substantially no resin layer at the site where the continuous layer from fiber reinforced plastic A and the continuous layer from fiber reinforced plastic B are in contact,
The point where the continuous layer from the fiber reinforced plastic A and one surface of the fiber reinforced plastic C intersect is defined as the intersection point P, and the point where the layer continuous from the fiber reinforced plastic B and the other surface of the fiber reinforced plastic C intersect is defined as the intersection point Q. The fiber reinforced plastic according to claim 9, wherein an angle formed between a line segment connecting the intersection point P and the intersection point Q and any surface of the fiber reinforced plastic C is smaller than 30 °.

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