JP5292972B2 - Manufacturing method of fiber reinforced plastic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fiber-reinforced plastic having excellent fluidity and complex form followability in the molding, and achieving excellent dynamic properties, low dispersibility and excellent dimensional stability as the fiber-reinforced plastic, and a manufacturing method therefor. <P>SOLUTION: The manufacturing method of the fiber-reinforced plastic for obtaining the fiber-reinforced plastic by integrally manufacturing prepreg base materials into a laminated body and press-molding the laminated body by arranging it in the mold, includes at least three steps of 1-3 for: (1) a lamination step of manufacturing the laminated body by cutting the cut prepreg base material with which the reinforcing fiber is cut so that the layer 11 in contact with the recessed part 5 has an area larger than a projected area of an opening of the recessed part 5, and forming a thin part 10 with the thickness of the laminated body getting thin toward the outer edge; (2) a setting step of arranging the thin part of the laminated body along the mold; and (3) a press step of press-molding by fluidizing the laminated body. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

    In the present invention, when a fiber reinforced plastic has good fluidity and molding followability, a laminate that exhibits excellent mechanical properties, low variation, and excellent dimensional stability is press-molded, and fiber reinforced plastic is obtained. The present invention relates to a method for producing a fiber-reinforced plastic. Such fiber reinforced plastics are particularly preferably used for structural members such as transport equipment such as automobiles and sports equipment such as bicycles.

  Fiber reinforced plastic consisting of reinforced fiber and matrix resin is attracting attention in industrial applications because it has high specific properties, high specific modulus, excellent mechanical properties, weather resistance, chemical resistance, etc. The demand is increasing year by year.

  As a molding method of fiber reinforced plastic having high functional properties, a semi-cured intermediate base material impregnated with matrix resin is laminated on continuous reinforcing fiber called prepreg, and heated and pressurized in a high temperature and high pressure kettle. Autoclave molding in which a matrix resin is cured and a fiber reinforced plastic is molded is most commonly performed. In addition, there is a wide range of press molding in which a laminate of the prepreg base material is preheated to supply the laminate in a softened state between a pair of male and female molds and then pressed to obtain a molded body of a desired shape. Has been done. In particular, press molding is characterized by the ability to produce a large amount of products with relatively uniform accuracy, and there are high demands for high speed, high accuracy, and stable quality in order to achieve mass production. In addition, the market demand for improving workability and moldability is very high.

  The fiber reinforced plastics obtained by these molding methods have excellent mechanical properties because they are composed of continuous fibers. Further, since the continuous fibers are regularly arranged, it is possible to design the mechanical properties required by the arrangement of the base material, and the variation in the mechanical properties is small. However, on the other hand, it is difficult to form a complicated three-dimensional shape having an uneven part, a double contour curved surface, and the like because the reinforcing fiber itself originally lacks elasticity. When such a continuous fiber base material is shaped, it is difficult to achieve high-quality shaping because it is stretched in places where the shape surface cannot be covered but wrinkles are generated in places where the base material remains. Even if it is a continuous fiber base material, if it can be sheared in-plane like a woven base material, it will be fairly easy to shape, but if the shape becomes complicated, fiber tension and wrinkles will still occur Therefore, at present, the actual situation is that it is mainly limited to members close to a primary curved surface or a planar shape.

  On the other hand, as a molding method suitable for a complicated three-dimensional shape such as a double contour curved surface or an uneven portion, there is press molding using SMC (sheet molding compound). In this molding method, the SMC sheet which is made into a semi-cured state by impregnating a chopped strand, which is usually cut to about 25 mm, with a thermosetting matrix resin, is heated and pressed using a press. In many cases, the SMC is cut to be smaller than the shape of the molded body before pressurization and placed on the mold, and is stretched (flowed) into the shape of the molded body by pressurization. Therefore, it is possible to follow complicated shapes such as uneven portions and double contour curved surfaces by the flow. However, SMC has a problem that distribution unevenness and alignment unevenness of the chopped strands are inevitably generated in the sheet forming process, so that the mechanical characteristics are lowered and the variation is increased. Furthermore, warpage, sink marks, and the like are likely to occur particularly in a thin member, which is often unsuitable as a structural material.

On the other hand, in order to fill the drawbacks of the materials as described above, a base material that can flow and reduce the variation in mechanical properties by cutting into a prepreg base material made of continuous fibers and a thermoplastic resin is disclosed. (For example, Patent Documents 1 and 2). However, compared with SMC, the mechanical properties are greatly improved and the variation is small, but it cannot be said that the strength is sufficient for application as a structural material. Compared to a continuous fiber base material, since it has a configuration including a defect called a notch, the notch which is a stress concentration point becomes a starting point of fracture, and there is a problem that particularly tensile strength and tensile fatigue strength are lowered.
Japanese Unexamined Patent Publication No. 63-247010 JP 9-254227 A

  The present invention has a good fluidity and a complicated shape followability at the time of molding in view of the background in which it was difficult to achieve both complex shape formation and low variation, sufficient strength, and handling in the prior art, An object of the present invention is to provide a fiber reinforced plastic and a method for producing the same, which exhibit excellent mechanical properties, low variability, and excellent dimensional stability when used as a fiber reinforced plastic.

In order to solve the above problems, the present invention has the following configuration. That is,
(I) After a prepreg base material composed of reinforcing fibers and matrix resin oriented in one direction is cut into a predetermined shape, the fiber direction of the prepreg base material is aligned in at least two directions and integrated to form a laminate. Further, the laminate is press-molded by placing it in a mold having a concave portion and a convex portion corresponding to the concave portion, and a cavity is formed between the concave portion and the convex portion, and fiber reinforced. A method for producing a fiber-reinforced plastic, which is a method for producing a fiber-reinforced plastic, comprising at least the following steps (1) to (3).
(1) A notch prepreg base material that has a notch on the entire surface of the prepreg base material and substantially all of the reinforcing fibers are cut by the notch, and at least a layer that is in contact with the concave part is formed of the concave part. Cut to have an area equal to or larger than the projected area of the opening, and at least part of the end of the laminate is laminated with respect to the number of laminations of the cut prepreg base material in the thickest portion of the laminate. Lamination process (2) for laminating the cut prepreg base material so as to form a thin part thinner than the thickness of the thickest part, formed by reducing the number by at least one layer or more. A step of placing the laminated body along at least part of the thin-walled portion of the laminated body along at least part of the end of the molding die; The formed laminate is molded The other type of pressing pressurized, the press step of the laminate are fluidized press molding of.

  (II) The cut prepreg base material used in the laminating step of (1) has a fiber length L of the reinforcing fibers divided by the cut in the range of 10 to 100 mm, and the fiber volume content Vf is The absolute value of the angle Θ between the cut and the reinforcing fiber is in the range of 2 to 25 °, and the projected length Ws projected in the vertical direction of the reinforcing fiber is 0. The manufacturing method of the fiber reinforced plastic as described in (I) which exists in the range of 0.1-1.5 mm.

  (III) The cut prepreg base material is laminated so that the thickness of the thin portion at the end of the laminate obtained in the lamination step (1) is 80% or less of the thickness of the cavity of the mold. The method for producing a fiber-reinforced plastic according to (I) or (II), wherein the laminate is obtained.

  (IV) In the laminating step of (1), the means for producing the laminated body cuts the prepreg base material according to a plurality of cut patterns offset toward the outer edge at at least a part of one end of the cut pattern. And the manufacturing method of the fiber reinforced plastic in any one of (I)-(III) which laminates | stacks the obtained some said prepreg base material, and obtains the said laminated body which has a thin part.

  (V) In the laminating step of (1), the cut pattern of the prepreg base material constituting the central layer other than both surface layers of the laminated body from the cut pattern of the prepreg base material constituting both surface layers of the laminated body. The method for producing a fiber-reinforced plastic according to any one of (I) to (III), wherein the laminated body having a thin portion is obtained by integrating the prepreg base material.

  (VI) The fiber according to any one of (I) to (V), wherein in the pressing step of (3), at least a part of the outer edge of the laminate is stretched to form a fiber-reinforced plastic having a standing wall. A method of manufacturing reinforced plastics.

  According to the present invention, the laminate to be press-molded has good fluidity and complex shape followability capable of forming complex shapes such as uneven portions and double contour curved surfaces, and when this is a fiber reinforced plastic, A fiber-reinforced plastic that exhibits excellent mechanical properties, low variability, and excellent dimensional stability can be obtained.

  The present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic enlarged view of a plane of a laminate used in the present invention. FIG. 2 is a schematic view of a mold having a concave portion and a convex portion corresponding to the concave portion in the present invention, and a cavity is formed between the concave portion and the convex portion. FIG. FIG. 2 b) is a projected view when the mold recess is viewed from above. FIG. 3 is a schematic view showing an example of a laminate having a thin portion in the present invention. FIG. 4 is a schematic view showing a state when the laminated body having the thin-walled portion is arranged in the mold.

The present invention has good fluidity capable of forming complex shapes such as uneven portions and double contour curved surfaces, and complex shape followability, and when made into a fiber reinforced plastic, it has excellent mechanical properties, its low variation, The manufacturing method for obtaining a fiber reinforced plastic exhibiting excellent dimensional stability has been intensively studied, and a reinforcing fiber (which may be simply referred to as “fiber” in this specification) is inserted through the entire surface. ) Is cut so that the area of the cut prepreg base material at least in contact with the concave side of the mold is equal to or greater than the projected area of the opening of the concave part, The cut prepreg base material is laminated so that the end portion forms a thin portion toward the outer edge to produce a laminate, and at least part of the thin portion of the laminate is at least part of the end portion of the mold In line with the mold It was clarified that this problem can be solved at once by arranging and press forming. In the present invention, “double contour curved surface” refers to a shape including at least part of a double curved surface or more. In addition, the “thin wall portion” is, as shown in FIG. 3 and FIG. 15, the laminated body 31 is configured by the cut prepreg base material 2 having a cut pattern having a plurality of dimensions. the laminated number of cutting prepreg base material in the parts, even without less laminated number is formed by less than one layer is that a thin region 10 than the thickness of the thickest portion. In addition, regarding the thickness of the thin portion 10, the thickness 32 of the thickest portion in the region (10 ′, 10 ″) along the mold, such as the region A or the region B, is set to “ The thickness of the thin part ”.
Further, “the thickness of the cavity of the mold” means the thickness 8 of the shape 7 formed at the end of the mold as shown in FIG. 2a).

In the present invention, the prepreg base material that has a notch on the entire surface of the prepreg base material and substantially all of the reinforcing fibers are cut by the incision, at least the layer in contact with the concave portion is the Cut to have an area equal to or larger than the projected area of the opening, and the number of stacks relative to the number of stacks of the cut prepreg base material in the thickest part of the stack in at least part of the end of the stack There is a laminating step in which a laminated body is produced by laminating so as to form a thin part thinner than the thickness of the thickest part formed by reducing at least one layer . As shown in FIG. 1, the laminate in the present invention has a unidirectional prepreg base material in which reinforcing fibers 1 are arranged in one direction, and the fiber orientation directions are aligned in at least two directions and integrated. In addition, a cut 3 is inserted over the entire surface of the unidirectional prepreg substrate, and substantially all of the reinforcing fibers are cut into short fibers by the cut. Composed.

  In the present invention, “substantially all the reinforcing fibers are cut by cutting” means that the area where the continuous fibers not cut by the cutting of the present invention are aligned is the prepreg base material area. It is less than 5% of the proportion. The “short fiber” is a concept used in comparison with a continuous fiber in which fibers are continuous over the entire length in the fiber direction, and refers to a fiber having a fiber length L of 100 mm or less. In the present invention, the laminate obtained by laminating the cut prepreg base material composed of the short fibers allows the fibers to flow in any direction in the layer at the time of molding. It is excellent in following complicated shapes such as parts. On the other hand, when the cutting is not performed, that is, when the reinforcing fibers of the laminated body are all composed of continuous fibers, the flow direction is hardly flowable and the flowable direction has anisotropy. It is extremely difficult to form complex shapes such as contoured curved surfaces.

Moreover, in this invention, it is excellent in the dimensional stability at the time of setting it as a fiber reinforced plastic by laminating | stacking in the direction from which the orientation of the reinforced fiber 1 differs. Furthermore, since the cut prepreg base material 2 in which the reinforcing fibers 1 are cut by the cut 3 causes anisotropy in the flow between the fiber direction and the fiber orthogonal direction when the fibers flow during molding, it is effective. In order to flow the fibers, it is important to laminate the reinforcing fibers in different directions. Among them, it is an isotropic laminate such as [0/90] _nS , [0 / ± 60] _nS , and [+ _45/0 / −45 / 90] _nS and a symmetrical laminate, so that the flow during molding is uniform. In view of the properties and warpage reduction in the case of a fiber reinforced plastic, it is preferable. Here, “the orientation of the reinforcing fibers is different” in the present invention means that the absolute value of the angle formed by the directions of the reinforcing fibers is 10 to 170 °.

Further, in the laminate according to the present invention, as shown in FIG. 3, at least the layer 11 in contact with the concave portion of the mold has an area of a projected area 9 ′ or more of the opening 9 of the concave portion shown in FIG. And, at least part of the end of the laminate is formed by reducing the number of laminations by at least one layer relative to the number of laminations of the cut prepreg base material in the thickest part of the laminate. The cut prepreg base material is laminated and produced so as to form a thin portion 10 thinner than the thickness of the thickest portion . The “projected area of the opening of the mold recess” refers to the area 9 ′ of the opening 9 indicated by hatching in the projection view when the mold recess shown in FIG. 2B) is viewed from above. In the present invention, the laminated body 31 having such a thin portion 10 is easily deformed at the end of the thin laminated body 31, and when the laminated body 31 is placed in a mold, as shown in FIG. It becomes easy to arrange along the mold. 4A) shows a state in which the laminate 31 is arranged in the concave portion of the mold, and FIG. 4B) shows a state in which the laminate is arranged in the convex portion of the mold. Further, at least the layer 11 in contact with the concave portion of the mold has an area that is greater than or equal to the projected area 9 ′ of the opening 9 of the concave portion so as to cover the entire opening of the concave portion of the mold and It is possible to follow the edge.

  In addition, the present invention provides a set step in which the laminate is disposed along a die at least a part of the thin portion 10 of the laminate along at least a part of an end of the mold, and the mold A pressing step in which the laminate placed on one of the molds is pressed against the other die of the molding die and pressed to cause the laminate to flow. In the present invention, when the laminate is disposed in the mold, as shown in FIG. 4, at least a part of the thin portion 10 of the laminate is formed on at least a part of the end of the mold. 5a), b), and c), the other layers of the laminate flow along the layer 11 in contact with the concave portion of the mold during press molding. At the end of the body, fiber reinforced plastic can be obtained without causing fiber orientation or disturbance of the layer structure 12. Furthermore, the laminated body can be positioned by placing the laminated body along the mold, and the quality variation caused by the misalignment of the laminated body during pressing can be reduced, and a molded body having a desired quality can be stably obtained. Can do.

  In the setting step, as shown in FIG. 4a), as shown in FIG. 4b, even if the laminate is disposed in the concave portion of the mold and is pressed and press-molded with the other convex portion, as shown in FIG. Even if the laminated body is arranged on the convex portion of the mold and is pressed and press-molded in the other concave portion, at least the layer 11 in contact with the concave portion of the laminated body has a projected area 9 of the opening 9 of the concave portion. If it has the above-mentioned area and is arranged along the mold, fiber flow may occur along the cavity of the mold when the mold is clamped. Here, when the layer 11 in contact with the concave part of the mold of the laminate does not have an area larger than the projected area 9 ′ of the opening 9 of the concave part, it cannot be arranged along the mold. As shown in FIG. 6, even when the laminate is pressed and the reinforcing fibers are flowed, the flow of the reinforcing fibers is disturbed on the wall surface at the end of the recess, and the fiber orientation and the layer structure of the obtained reinforcing fiber plastic are disturbed. 13 occurs, and the surface quality is deteriorated, and the mechanical characteristics and dimensional stability vary.

In addition, at least the layer 11 in contact with the recess has an area that is greater than or equal to the projected area 9 ′ of the opening 9 of the recess, but the cut in the thickest part of the stack is at least part of the end of the stack. When the thin- walled portion 10 thinner than the thickness of the thickest portion is formed by reducing the number of stacked layers by at least one or more layers relative to the number of stacked prepreg base materials , that is, When the thickness is substantially uniform throughout, the thickness of the laminate is strongly influenced by the cavity size of the mold, and it is difficult to stably obtain a desired fiber-reinforced plastic. Here, “the thickness of the laminate is affected by the cavity size of the mold” means that the thickness of the laminate is larger than the thickness of the cavity of the mold and that the laminate is further along the mold. In the case where the thickness of the laminate is so thick that it is difficult to dispose, even if press-molded, as shown in FIG. 7a), the reinforcing fiber stretches at the end 14 of the mold, and the resin at the end of the molded product The problem is that the reservoir 15 is formed or the shape is not formed. Even if the laminated body can be arranged along the mold, as shown in FIG. 7b), the end 14 of the molding die hits the end 16 of the laminated body when the mold is clamped. There arise problems that the surface quality of the obtained fiber reinforced plastic is remarkably lowered and the layer structure is disturbed. When the thickness of the laminated body is smaller than the thickness of the cavity of the molding die, a space is generated between the laminated body and the molding die regardless of the arrangement of the laminated body. And the desired shape cannot be obtained.

  Further, when the layer 11 in contact with the concave portion does not have an area equal to or larger than the projected area of the opening 9 of the concave portion, as shown in FIG. Even if the reinforcing fiber is pressed and flowed, the flow of the reinforcing fiber is disturbed at the end wall surface of the recess, and the fiber orientation and the layer structure of the obtained reinforcing fiber plastic are disturbed, resulting in variations in mechanical properties and dimensional stability. Will occur.

  As for the cut prepreg base material constituting the laminate in the present invention, as shown in FIG. 8, the prepreg base material has a cut 3 on the front surface, and substantially all the reinforcing fibers 1 are cut. 3, the reinforcing fiber is preferably cut into short fibers having a fiber length L (21) in the range of 10 to 100 mm. As described above, the laminate obtained by laminating the cut prepreg base material 2 composed of the short fibers allows the fibers to flow in any direction in the layer at the time of molding. It is excellent in following complicated shapes such as parts. Here, when the fiber length L is smaller than 10 mm, although the fluidity is improved, the reinforcing effect by the fiber is lowered, and sufficient mechanical properties may not be obtained when the fiber reinforced plastic is obtained. On the other hand, when the fiber length L is larger than 100 mm, the flow of the fiber during molding becomes worse and it becomes difficult to form a complicated shape. Considering both characteristics of moldability and physical properties, the fiber length L is more preferably in the range of 20 to 60 mm. However, depending on the shape of the cut part and the industrial process, fibers shorter than 10 mm may be mixed in a part of the cut prepreg base material, but substantially 95% or more of the total fiber amount. If the fiber is within the range of 10 to 100 mm, there is no problem in moldability and physical properties.

  Further, the reinforcing fiber of the cut prepreg base material in the present invention has an absolute value of an angle Θ (hereinafter also referred to as a cut angle) formed by the cut 3 and the fiber direction 17 shown in FIG. It is preferable that it is cut within a range of 25 °. Even if the absolute value of Θ is larger than 25 °, fluidity can be obtained, and higher mechanical properties can be obtained as compared with conventional SMC, etc., but in particular, when the absolute value of Θ is 25 ° or less. Significant improvement in mechanical properties. On the other hand, if the absolute value of Θ is smaller than 2 °, sufficient fluidity and mechanical properties can be obtained, but it is difficult to make a stable cut. That is, when the incision lies on the fiber, the fiber easily escapes from the blade when making the incision, and the proportion of uncut fibers present in the prepreg base material increases. Moreover, in order to make the fiber length L 100 mm or less, when the absolute value of Θ is smaller than 2 °, production stability is lacking, such as at least the shortest distance between notches being smaller than 0.9 mm. In addition, when the distance between the cuts is small as described above, there is a problem that handling at the time of stacking becomes difficult. In view of the relationship between the ease of controlling the cutting and the mechanical characteristics, it is more preferably in the range of 5 to 15 °. Note that Θ in the present invention means that when an arbitrary point on the cut is a point X, if the angle formed by the fiber longitudinal direction and the cut at the point X is θ (X), Θ is θ (X ) Is the average value on the notch, that is, the value given by (Equation 1). Here, as shown in FIG. 8, the end points of the incision 3 are point A and point B, respectively, the points A and B are connected, the curve along the incision is C, and the curve C at the point X is The minute line segment is ds.

  Furthermore, below, an example of the preferable cutting pattern in the said cutting prepreg base material is demonstrated using FIG.

  A plurality of controlled and aligned cuts 3 are made on a prepreg base material in which the reinforcing fibers 1 are aligned in one direction. The fibers are divided at the notches 3 that form pairs in the fiber orientation direction, and the interval 21 is set to 10 to 100 mm, so that substantially all the reinforcing fibers 1 on the notched prepreg substrate 2 have a fiber length L. It can be 10-100 mm. As shown in FIG. 9, if the angle 19 between the notch 3 and the reinforcing fiber 1 is Θ, the absolute value of Θ is in the range of 2 to 25 ° over the entire surface. FIG. 10a shows an example in which the absolute value of Θ exceeds 90 ° and b exceeds 25 °. However, in these examples, the high strength that can be obtained by the present invention cannot be expressed.

  FIG. 11 shows a prepreg substrate having five different cutting patterns. The cut prepreg base material 2 in FIG. 11a) has slanted continuous and straight cuts 3b arranged at equal intervals. The cut prepreg substrate 2 in FIG. 11b) has skewed continuous, straight cuts 3b arranged at two different intervals. The cut prepreg substrate 2 in FIG. 11c) has continuous, curved (meandering) cuts 3 arranged at equal intervals. The cut prepreg substrate 2 in FIG. 11d) has intermittent linear cuts 3a arranged at equal intervals and skewed in two different directions. The cut prepreg base material 2 of FIG. 11e) has skewed intermittent linear cuts 3a arranged at equal intervals. The incision may be a curved line as shown in FIG. 11c), but a straight line as shown in FIGS. 11a), b), d), and e) is preferable because the fluidity can be easily controlled. Further, the length L of the reinforcing fiber divided by the cut may not be constant as shown in FIG. 11b), but if the fiber length L is constant over the entire surface, the fluidity can be easily controlled and the strength varies. Can be further suppressed, which is preferable. Here, the prescribed linear shape means a state in which a part of a geometrical straight line is formed. However, as long as the effect of facilitating the fluidity control is not impaired, Even if there is a portion that does not form a part of the straight line, there is no problem. As a result, even if there is a portion where the fiber length L is not constant over the entire surface (in this case, the fiber length L is substantially over the entire surface). It can be said that it is constant).

  As a more preferable example [1], it is preferable that the cuts 3 are continuously formed as shown in FIGS. In the pattern of Example [1], since the cut 3b is not intermittent, flow turbulence does not occur in the vicinity of the cut end, and all the fiber lengths L are constant in the region where the cut 3b is inserted. The flow is stable. In order to prevent the cut prepreg base material 2 from falling apart because the cuts 3b are continuously formed, an area where the cut is not connected to the peripheral portion of the cut prepreg base material 2 is provided. Or by gripping with a support such as a sheet-like release paper or film that is not cut, the handling property can be improved.

  Further, as another preferable example [2], as shown in FIG. 8, when Ws (20) is a length obtained by projecting the cut in the vertical direction of the reinforcing fiber, Ws is in the range of 30 μm to 100 mm. Intermittent cuts 3a are provided on the entire surface of the cut prepreg substrate 2, and the geometric shapes of the cuts 3a1 and the cuts 3a2 adjacent to the cuts 3a1 in the fiber orientation direction may be the same. Here, the “projection length Ws obtained by projecting the cut in the vertical direction of the reinforcing fiber” means that the vertical direction of the reinforcing fiber (direction perpendicular to the fiber 18) is the cut in the plane of the prepreg layer as shown in FIG. As a projection surface, the length 20 when projected perpendicularly to the projection surface from the cut (fiber orientation direction 17) is indicated. When Ws is 30 μm or less, it is difficult to control the cutting, and it is difficult to ensure that the fiber length L is 10 to 100 mm over the entire surface of the cut prepreg substrate. That is, there is a problem that if there is a fiber that has not been cut by cutting, the fluidity of the base material is remarkably lowered, and if it is cut excessively, a portion where L is less than 10 mm appears. Conversely, when Ws is greater than 10 mm, the strength is almost constant. That is, when the fiber bundle end becomes larger than a certain value, the load at which breakage starts becomes substantially equal. FIG. 8 shows an example in which both L and Ws are one type. Any of the cuts 3a (for example, 3a1) has another cut 3a (for example, 3a2) that overlaps by translating in the fiber direction. The fiber length can be stably increased by the presence of a width in which the fibers are divided by adjacent cuts at a fiber length shorter than the fiber length L divided by the cuts 3a that form pairs in the fiber direction. The cut prepreg base material 2 can be manufactured with a thickness of 100 mm or less. In the pattern of Example [2], when the obtained cut prepreg base material 2 is laminated, the cut is intermittent, and thus the handleability is excellent. Although other patterns are illustrated in FIGS. 11d) and 11e), any pattern may be used as long as the above conditions are satisfied.

  In the preferred example [2], the length Ws projected in the vertical direction of the reinforcing fiber is preferably in the range of 0.1 to 1.5 mm from the viewpoint of mechanical properties. By reducing Ws, the amount of fibers cut by each cutting is reduced, and strength improvement is expected. In particular, when Ws is 1.5 mm or less, a great improvement in strength is expected. In addition, the longer the cut length, the easier it is for the base material notches to open during the laminating operation, and the handleability of the base material is greatly reduced. If the cut is 1.5 mm or less, the cut is less likely to open during the laminating operation, and a cut prepreg base material with good substrate handling properties is obtained. In the present invention, when the absolute value of the cutting angle Θ is 2 to 25 °, the projection length Ws can be reduced with respect to the cutting length. Therefore, even if it is the minimum notch | incision whose Ws is 1.5 mm or less, it becomes possible to provide industrially stably. Further, when the cutting is inserted into the prepreg base material by pressing the blade, the reinforcing fiber may meander in the direction perpendicular to the fiber at the time of cutting and escape from the blade, so that the fiber may not be cut well. In order to reduce the influence of such fiber escape, Ws is preferably 0.1 mm or more. More preferably, by setting Ws to 0.2 mm or more, it becomes possible to insert the cut into the prepreg base material without leaving more continuous fibers.

  The characteristics of the cut prepreg base material used in the present invention will be described with reference to FIGS. As a comparison of the present invention, FIG. 12 shows a laminated body 22 in which a cut prepreg base material 2 having an absolute value of an angle Θ between the cut 3 and the reinforcing fiber 1 of 90 ° is laminated a), and the laminated body 22 is The formed fiber reinforced plastic 23 b) is a plan view showing a close-up of the layer derived from the cut prepreg substrate 2 and a cross-sectional view taken along the line AA of the plan view. As shown in a), the cut prepreg base material 2 is provided with a cut perpendicular to the fiber on the entire surface, and the cut 3 penetrates the thickness direction of the layer. By setting the fiber length L to 100 mm or less, fluidity is ensured, and the fiber reinforced plastic 23 whose area is easily extended from the laminate 22 can be easily obtained by press molding or the like (however, the thickness is reduced). As in b), when the elongated fiber reinforced plastic 23 is obtained, the short fiber layer 24 derived from the cut prepreg base material 2 extends in the direction perpendicular to the fiber and has no fiber (cut opening). 25 is generated. This is because the reinforcing fiber generally does not expand at a pressure of the molding level. In the case of FIG. 12, the cut opening 25 is generated for the extended length, for example, from 250 × 250 mm laminates 22 to 300. When the fiber reinforced plastic 23 having a size of 300 mm is obtained, the total area of the cut openings 25 is 50 × 300 mm, that is, 1/6 (about 16.7 with respect to the surface area of the fiber reinforced plastic 23 having a size of 300 × 300 mm. %) Is the calculation for the cut opening. As shown in the sectional view, the region 25 is occupied by the adjacent layer 27 and the region where the resin-rich portion 28 and the adjacent layer 27 enter. Therefore, when the laminated body 22 using the cut prepreg base material 2 is stretched and formed, the undulation 29 of the layer and the resin rich portion 28 are generated at the fiber bundle end portion 26, which causes a decrease in mechanical properties and surface quality. Affects decline. In addition, since the rigidity is different between a portion where the fiber is present and a portion where the fiber is not present, the fiber reinforced plastic 23 is an in-plane anisotropic fiber, which is difficult to design due to problems such as warping. Further, in terms of strength, fibers oriented to about ± 10 ° or less from the load direction transmit most of the load, but the fiber bundle end portion 26 must redistribute the load to the adjacent layer 27. Don't be. At that time, as shown in FIG. 12b), when the fiber bundle end portion 26 is perpendicular to the load direction, stress concentration is likely to occur, and peeling is also likely to occur. Therefore, the strength improvement cannot be expected so much.

  On the other hand, FIG. 13 shows a laminate 22 in which the cut prepreg base material 2 of the preferred example [1] of the present invention is laminated in a), and a fiber reinforced plastic 23 in which the laminate 22 is molded in b). The top view which closed the layer derived from the embedded prepreg base material 2, and the sectional view which cut out the AA cross section of the top view were shown. As shown in a), the cut prepreg base material 2 is provided with continuous cuts 3b having an absolute value of the angle Θ between the fibers 1 of 25 ° or less, and the cuts 3b are arranged in the thickness direction of the layers. It has penetrated. By setting the fiber length L to 100 mm or less, the fluidity is ensured, and the fiber reinforced plastic 23 whose area is easily extended from the laminate 22 can be obtained by press molding or the like. When the stretched fiber reinforced plastic 23 is obtained as in b), the short fiber layer 24 derived from the cut prepreg base material 2 stretches in the direction perpendicular to the fiber, and the fiber 1 itself rotates 30 to expand the stretched region. In order to increase the area, a region (cut opening) 25 in which no fiber exists as shown in FIG. 12 is not substantially generated, and the area of the cut opening existing on the layer surface is 0 compared to the surface area of the layer. Within the range of 1 to 10%. Therefore, as can be seen from the sectional view, the adjacent layer 27 does not penetrate, and the high-strength and high-quality fiber-reinforced plastic 23 without the undulation 29 and the resin-rich portion 28 can be obtained. Since the fibers 1 are arranged all over the surface, there is no difference in rigidity in the surface, and the design can be easily applied as in the conventional continuous fiber reinforced plastic. The revolutionary effect that this fiber rotates and stretches to obtain a fiber-reinforced plastic having no layer waviness is that the absolute value of the angle Θ between the cut and the reinforcing fiber is 25 ° or less, and the cut is It can be obtained for the first time by being put continuously. In addition, in terms of strength, when attention is paid to the fibers oriented to about ± 10 ° or less from the load direction as described above, the fiber bundle end portion 26 lies down with respect to the load direction as shown in FIG. 13b). I can see the situation. Since the fiber bundle end portion 26 is slanted in the layer thickness direction, load transmission is smooth, and peeling from the fiber bundle end portion 26 hardly occurs. Therefore, a marked improvement in strength is expected compared to FIG. The fiber bundle end portion 26 is inclined in the layer thickness direction because when the fiber 1 rotates, there is a gentle distribution in the rotation 30 of the fiber 1 from the upper surface to the lower surface due to friction between the upper surface and the lower surface. Therefore, it is considered that the existence distribution of the fibers 1 occurs in the layer thickness direction, and the fiber bundle end portion 26 is inclined in the layer thickness direction. In such a layer of fiber reinforced plastic 23, a fiber bundle end portion which is slanted in the layer thickness direction is formed, and the epoch-making effect of remarkably improving the strength is that the absolute value of the angle Θ formed with the fiber 1 of the cut 3b is 25 It can be obtained for the first time when it is below °.

  In FIG. 14, the laminated body 22 in which the cut prepreg base material 2 of the preferred example [2] of the present invention is laminated is shown in a), and the fiber reinforced plastic 23 in which the laminated body 22 is molded is shown in b). The top view which closed up the layer derived from the base material 2 was shown. As shown in a), the cut prepreg base material 2 is provided with intermittent cuts 3a having an absolute value of the angle Θ between the fibers 1 of 25 ° or less, and the cuts 3a are in the layer thickness direction. Through. By making the fiber length L to be 100 mm or less over the entire surface of the cut prepreg base material 2 by the cut 3a, the fluidity is ensured, and the fiber reinforced plastic 23 whose area is easily extended from the laminate 22 by press molding or the like. Can be obtained. By reducing the cut length and the cut angle, the projection length Ws obtained by projecting the cut in the vertical direction of the reinforcing fiber can be made 1.5 mm or less. When the stretched fiber reinforced plastic 23 is obtained as in b), the short fiber layer 24 derived from the cut prepreg base material 2 does not stretch in the fiber direction when stretched in the fiber vertical direction. A non-existent region (cut opening) 25 is generated, but the adjacent short fiber group flows in the direction perpendicular to the fiber, thereby filling the cut opening 25 and reducing the area of the cut opening 25. This tendency becomes remarkable particularly when the projected length Ws obtained by projecting the cut in the vertical direction of the reinforcing fiber is 1.5 mm or less, and the cut opening 25 is not substantially generated and exists on the layer surface. The area of the cut opening can be in the range of 0.1 to 10% compared to the surface area of the layer. Accordingly, the adjacent layer 27 does not invade in the thickness direction, and a high-strength and high-quality fiber-reinforced plastic 23 without the layer undulation 29 or the resin-rich portion 28 can be obtained. Since the fibers 1 are arranged all over the surface, there is no difference in rigidity in the surface, and the design can be easily applied as in the conventional continuous fiber reinforced plastic. The epoch-making effect of filling the notch opening with the flow in the direction perpendicular to the fiber to obtain a fiber-reinforced plastic without layer waviness is that the absolute value of the notch angle Θ is 25 ° or less and the notch is made of the reinforcing fiber It can be obtained for the first time when the projection length Ws projected in the vertical direction is 1.5 mm or less. More preferably, when Ws is 1 mm or less, higher strength and higher quality can be achieved.

  In the present invention, the fiber volume content Vf is preferably in the range of 45 to 65%. Sufficient fluidity can be obtained when the fiber volume content Vf is 65% or less. The lower the Vf, the better the fluidity, but if Vf is less than 45%, the high mechanical properties required for the structural material may not be obtained. Considering the relationship between fluidity and mechanical properties, it is more preferably in the range of 55-60%.

  Furthermore, examples of the reinforcing fibers constituting the prepreg base material in the present invention include organic fibers such as aramid fibers, polyethylene fibers, polyparaphenylene benzoxador (PBO) fibers, glass fibers, carbon fibers, silicon carbide fibers, and alumina fibers. In addition, inorganic fibers such as Tyranno fiber, basalt fiber, and ceramic fiber, metal fibers such as stainless steel fiber and steel fiber, and other reinforcing fibers using boron fiber, natural fiber, modified natural fiber, and the like as fibers. Among them, carbon fiber is particularly lightweight among these reinforced fibers, and has particularly excellent properties in specific strength and specific modulus, and is also excellent in heat resistance and chemical resistance. Is suitable for a member such as an automobile panel. Among these, PAN-based carbon fibers that can easily obtain high-strength carbon fibers are preferable.

  In addition, the matrix resin used for the prepreg substrate in the present invention is a thermoplastic resin such as polyamide, polypropylene, or polyethylene, even if it is a thermosetting resin such as epoxy resin, polyester resin, vinyl ester resin, or phenol resin. Or a mixed resin thereof. However, since it is necessary to pressure-bond the prepreg base material at the time of lamination, a semi-cured thermosetting resin excellent in tackiness is more suitable. Among these, as such a thermosetting resin, an epoxy resin is preferable in consideration of tackiness in a process of pasting and mechanical characteristics when a fiber reinforced plastic is used. When a thermoplastic resin is used, it is preferable to preheat and laminate in order to ensure tackiness. In this case, the heating temperature is preferably set to a temperature at which the thermoplastic resin used can maintain a semi-cured state in a series of lamination steps.

  In the present invention, it is preferable to produce the laminate so that the thickness of the thin portion at the end of the laminate is 80% or less of the thickness of the cavity of the mold. Considering the fluidity of the fibers, the thickness of the thin wall portion at the end of the laminate is more preferably 65 to 75% of the thickness of the cavity of the mold. If the thickness of the thin portion is larger than 80%, the thickness of the laminate does not affect the cavity size of the laminate as in the case where the thickness of the entire laminate is uniform without forming the thin portion. The effect of the effect will increase as it increases beyond 80%. Accordingly, it is difficult to arrange along the mold, or the other mold that is pressed during mold clamping hits the end of the laminate, and the desired shape cannot be obtained. There are problems that the layer structure of the body collapses and the mechanical properties deteriorate, and the surface quality deteriorates significantly. In consideration of the possibility that a portion where the fiber is not filled at the end of the molded product is generated even if the fiber is flowed, the thickness of the thin portion is preferably 65% or more. In addition, when placing the laminate, there is no particular limitation on the length of the thin portion along the mold, but the length in the pressing direction is determined when the shape of the target molded product is a deep-drawn shape. Since it is necessary to flow to a bulky position, the length is preferably at least 20% of the dimension of the deep-drawn shape portion of the molded product.

  In the present invention, the means for producing the laminate having the thin-walled portion is preferably performed by any of the following methods.

  First, as the method [1], as shown in FIG. 3, the cut prepreg base material 2 is cut according to a plurality of cut patterns offset toward the outer edge in at least a part of one end of the cut pattern. It is preferable to obtain the laminated body 31 having the thin portion 10 by laminating the cut prepreg base materials 2 of several shapes. Here, “the cut pattern offset toward the outer edge of the end portion of one cut pattern” means a portion corresponding to the end portion of the laminated body where the thin portion 10 is to be formed with respect to a certain cut pattern. This is a cut pattern in which a taper shape or a step is formed at the end of the laminated body by the layer of the prepreg base material. Here, this region A corresponds to the thin-walled portion 10 and is a portion along the mold when the laminated body 31 is arranged in the mold. Here, as described above, it is preferable that the thickness 32 of the thin laminate portion 10 in this region A is 80% or less of the thickness 8 of the cavity of the mold.

  As an example of a preferable shape of the laminate 31 obtained by this method [1], the area of the layer 11 in contact with the concave portion 5 of the mold has an area larger than the projected area of the opening 9 of the concave portion, and It is preferable that the area of the layer in contact with the convex portion 4 of one of the molding dies is the largest among the cut prepreg base materials 2 constituting the laminated body 31. Here, as shown in FIG. 3a), the thin portion 10 may be formed by gradually changing the area of each layer constituting the laminate from the maximum area to the minimum area for each layer, or as shown in FIG. 3b). The several layers of precursors having the same cut pattern, that is, the cut prepreg base material 2 having the same area are laminated to form a laminate precursor 33 and offset with respect to a certain laminate precursor 33. You may form a laminated body which has the one thin part 10 by laminating | stacking a body. Further, the width Wa (34) of the region A shown in FIG. 3 is not limited, but as described above, when forming a deep-drawn shape, the dimension of the thin portion along the mold is the depth of the molded product. It is preferable that the length is at least 20% of the size of the drawn shape portion, and accordingly, the width Wa of the region A is preferably longer than 20% of the size of the deep drawn shape portion.

  Next, as the method [2], as shown in FIG. 15, the prepreg base constituting the central layer other than the outermost layer of the laminate from the cut pattern of the prepreg base material constituting the outermost layer of the laminate. It is preferable to obtain a laminate 31 having a thin portion by reducing the cut pattern of the material and integrating the prepreg base material. Here, “both surface layers of the laminate” refers to the layer 37 that contacts the mold during press molding, and “a central layer other than both surface layers” refers to a laminate that does not contact the mold during press molding. It refers to all the cut prepreg base materials 38 to be constructed. In this method [2], the cut pattern of the central layer is made smaller than the cut pattern of both surface layers, so that the region B (10 ″) shown in FIG. In this method, this region B becomes a portion along the mold when the laminated body 31 is placed in the mold, where the region B is as described above. It is preferable that the thickness of the thin-walled portion of the laminated body is 80% or less of the thickness of the cavity of the mold.In the shape obtained by this method, the thickness of the thin-walled portion is a region as shown in FIG. In B, it is set as the sum (36) of the thickness (36 ', 36 ") of the thickest part of the part which changes gradually toward both surface layers. The laminated body 31 having a thin part obtained by this method has a shape in which one surface layer is in contact with the mold as in the method [1] because both surface layers 37 serve as guides for the flow path of the central layer 38. Unlike this, there is no friction between the mold and the flowing fibers, and higher fluidity can be ensured.

  As an example of a preferable shape of the laminate obtained by this method [2], both surface layers 37 of the laminate in contact with the mold have an area equal to or larger than the projected area of the opening 9 of the concave portion of the laminate, and It is the largest among the cut prepreg base materials constituting the laminate 31, and the layers other than both surface layers of the laminate, that is, the central layer 38 is preferably small with respect to the areas of both surface layers. Here, as shown in FIG. 15a), the thin portion 10 may be formed such that the area of the central layer 38 gradually decreases with respect to both surface layers 37, or several layers from each surface layer. Has the same shape and area as the surface layer, that is, the laminated body precursor 33 is formed with the same cut pattern, and the other central layer has a cut pattern smaller than both surface layers and has a smaller area than the laminated body precursor 33. The thin portion may be formed by forming the precursor 33 ′ and forming a sandwich shape as shown in FIG. Further, although there is no limit on the width Wb (35) of the region B shown in FIG. 15, as described above, when forming a deep drawing shape, the dimension of the thin portion to be folded into the region that becomes a cavity is the size of the molded product. It is preferable that the length is at least 20% of the dimension of the deep-drawn shape portion, and accordingly, the width Wb of the region B is preferably longer than 20% of the dimension of the deep-drawn shape portion.

  In the present invention, in the pressing step, at least a part of the outer edge of the laminate can be stretched to form a fiber reinforced plastic having a standing wall. Here, the “standing wall” is a concept that is used in distinction from the concavo-convex shape, the shape changes within a range of 90 ° ± 10 ° with respect to a certain surface, and the height from a certain surface is 20 mm or more. Refers to things. Here, the height when forming the standing wall is not particularly limited, but if the height is too high, the fiber may not flow sufficiently to the tip of the standing wall, and the shape may not be obtained, so that it is 50 mm or less. Is preferred. More preferably, it is 40 mm or less.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not particularly limited thereto.

<Fiber-reinforced plastic molding and evaluation of moldability>
As shown in FIG. 16, the mold 39 used in the main molding includes three uneven portions 40 on a 200 × 150 mm flat plate, and a standing wall having a height of 40 mm is formed on four surfaces around the mold. The cavity 41 is provided. In addition, the thickness dimension of the cavity used as a standing wall is 2 mm. A laminate composed of a cut prepreg base material is placed in the center of the concave part of the mold so that the thin part is along the peripheral wall surface of the concave part. Was cured under conditions of 150 ° C. × 30 minutes under a pressure of 6 MPa. This obtained the molded object of the fiber reinforced plastic.

  As for fluidity, when the base material is stretched and molded, fiber reinforced plastic is filled in the mold cavity, and when it is stretched until a desired standing wall is formed, fluidity ○, gold Although the fiber cavity is filled with fiber reinforced plastic, but the base material placed on the outermost layer is not stretched, the fluidity is Δ, and the mold cavity is not filled with fiber reinforced plastic. In some cases, it was evaluated as fluidity x.

  For sleds, if the molded body is placed on a flat test bench and the molded body is in contact with the entire surface of the test bench, the sled ○, and the molded body can be tested by placing the molded body on a flat test bench. When the molded body is not in contact with the entire surface and the molded body is in contact with the entire surface of the test table with the finger when the molded body is pressed against the entire surface of the test table, warping is required. When the molded body was pressed against the table, if there was a portion where the molded body was not in contact with the test table, it was evaluated as a sled x.

  Furthermore, cross-sectional observation of the standing wall corner is performed to confirm whether the layer structure is maintained. If the layer structure is maintained, the layer structure ○, fiber tension and resin accumulation occur, and part of the layer structure When it was not kept, it was evaluated as a layer structure Δ, and when it was not kept at all, it was evaluated as a layer structure ×.

<Mechanical property evaluation>
A tensile strength test piece was obtained by cutting into a length of 180 ± 1 mm and a width of 25 ± 0.2 mm from the flat plate portion of the fiber reinforced plastic obtained by the above procedure. In the test, the tensile strength was measured at a crosshead speed of 2.0 mm / min with the distance between the grippers set to 100 mm. In this example, an Instron (registered trademark) universal testing machine 4208 type was used as a testing machine. The number of test pieces measured was n = 5, and the average value was the tensile strength. Further, a standard deviation was calculated from the measured value, and the standard deviation was divided by an average value, thereby calculating a variation coefficient (CV value (%)) as an index of variation.

(Example 1) [Laminated body shape: method [1] formula, cutting form: continuous]
Epoxy resin ("Epicoat (registered trademark)" 828: 30 parts by weight, "Epicoat (registered trademark)" 1001: 35 parts by weight, "Epicoat (registered trademark)" 154: 35 parts by weight, manufactured by Japan Epoxy Resin Co., Ltd. Then, 5 parts by weight of a thermoplastic resin polyvinyl formal (“Vinylec (registered trademark)” K manufactured by Chisso Corporation) was heated and kneaded with a kneader to uniformly dissolve the polyvinyl formal, and then a curing agent dicyandiamide (Japan Epoxy Resin Co., Ltd.) ) DICY7) 3.5 parts by weight and 4 parts by weight of curing accelerator 3- (3,4-dichlorophenyl) -1,1-dimethylurea (Hodogaya Chemical Co., Ltd. DCMU99) were kneaded in a kneader. Thus, an uncured epoxy resin composition was prepared. This epoxy resin composition was applied onto a release paper having a thickness of 100 μm that had been subjected to silicone coating using a reverse roll coater to prepare a resin film. Next, a resin film is laminated on both sides of carbon fibers arranged in one direction (tensile strength 4,900 MPa, tensile elastic modulus 235 GPa), and the resin is impregnated by heating and pressing, so that the carbon fiber weight per unit area is increased. A prepreg base material having a thickness of 125 g / m ² , a fiber volume content Vf of 55%, and a thickness of 0.125 mm was prepared. As shown in FIG. A straight cut 3b having a direction of 10 ° with respect to the direction was continuously inserted, and the reinforcing fiber 1 was cut so that the length in the fiber direction was 30 mm. The cut prepreg base material 2 is 224 × 174 mm, 216 × 166 mm, 208 × 158 mm, 195 in the fiber orientation direction (0 ° direction) and in the direction shifted 45 degrees to the right from the fiber orientation direction (45 ° direction), respectively. A prepreg base material having four types of sizes of 145 mm and having regular cuts at equal intervals was obtained. Here, no incision was made in 5 mm around each incision prepreg base material, so that it was not separated by continuous incision. In addition, since the cut length of the cut prepreg base material was long, there was some difficulty in handling of the prepreg base material such as misalignment of the base material in the lamination process.

After laminating four layers of the cut prepreg base materials cut into the above four types to produce a laminate precursor 33, the four types of obtained laminate precursors were laminated in order of increasing area. A laminate 31 having a thin portion as shown in FIG. At this time, 16 layers were laminated in a pseudo isotropic _{manner so that} the layered structure of the laminate was [−45 / 0 / + 45/90] _2S . The width Wa of the thin portion of the laminate is 12 mm (30% of the height of the standing wall), and the thickness 32 of the thickest portion 10 along the mold is 1.5 mm (the thickness of the cavity). 75%).

  The laminated body 31 comprised by the obtained cut prepreg base material 2 was shape | molded with the said method, and the fiber reinforced plastic which has an uneven | corrugated | grooved part and a standing wall was obtained. Here, when installing the laminated body 31 in a metal mold | die, the thin part deform | transformed along the wall surface of a shaping | molding die recessed part, and it was able to arrange | position and position easily.

  The obtained fiber reinforced plastic exhibited good surface smoothness, the fibers were along the shape of the concavo-convex portion, and no wrinkles were generated. Further, the fiber was filled up to the tip of the cavity of the standing wall portion, and the standing wall having a desired height was formed. When the standing wall portion of the fiber reinforced plastic was cut out and the cross section was observed, the layer structure was maintained even at the corner portion of the standing wall, and no fiber tension was observed. In addition, the layer structure up to the leading end of the standing wall was continuous, and the layer composed of fibers arranged in the same direction as the stretching direction was not interrupted and maintained a uniform thickness. The tensile modulus of the flat plate section cut out from the obtained fiber reinforced plastic is expressed as 46 GPa almost as the theoretical value, and the tensile strength is as high as 590 MPa, and the CV value is also very small as 5%. As a result. From these results, it was found that mechanical properties and quality that can be applied to structural materials and outer plate members were obtained.

(Example 2) [Laminated body shape: method [1] formula, cutting form: intermittent]
As shown in FIG. 18, a fiber reinforced plastic having a concavo-convex portion and a standing wall shape was obtained in the same manner as in Example 1 except that the way of inserting the cuts was intermittent. The fiber length L of the notched prepreg base material 2, the angle Θ between the notch and the fiber direction, and the projected length Ws obtained by projecting the notch in the vertical direction of the reinforcing fibers are L = 30 mm, Θ = 10 °, Ws = 0.51 mm. In addition, the cut prepreg base material 2 obtained by this method has a shorter cut length than the first embodiment, and the base material is not deformed in the stacking step, and a laminate can be easily obtained. done.

  The obtained fiber reinforced plastic exhibited good surface smoothness equivalent to that of Example 1, the fibers were along the shape of the concavo-convex portion, and no wrinkles were generated. Further, the fiber was filled up to the tip of the cavity of the standing wall portion, and the standing wall having a desired height was formed. When the standing wall portion of the fiber reinforced plastic was cut out and the cross section was observed, the layer structure was maintained even at the corner portion of the standing wall, and no fiber tension was observed. In addition, the layer structure up to the leading end of the standing wall was continuous, and the layer composed of fibers arranged in the same direction as the stretching direction was not interrupted and maintained a uniform thickness. About the tensile strength of the flat plate part cut out from the obtained fiber reinforced plastic, a value higher than 650 MPa and Example 1 was expressed.

(Examples 3 to 7) [Comparison of fiber length (Table 1)]
A fiber reinforced plastic having a concavo-convex portion and a standing wall shape was obtained in the same manner as in Example 1 except that the fiber length L was changed by changing the notch interval. L was 7.5 mm in Example 3, 10 mm in Example 4, 60 mm in Example 5, 100 mm in Example 6, and 120 mm in Example 7.

  The obtained fiber reinforced plastics exhibited good surface smoothness except for Examples 6 and 7, the fibers were along the shape of the concavo-convex portions, and no wrinkles were generated. Further, the fiber was filled up to the tip of the cavity of the standing wall portion, and the standing wall having a desired height was formed. When the standing wall portion of the fiber reinforced plastic was cut out and the cross section was observed, the layer structure was maintained even at the corner portion of the standing wall, and no fiber tension was observed. In addition, the layer structure up to the leading end of the standing wall was continuous, and the layer composed of fibers arranged in the same direction as the stretching direction was not interrupted and maintained a uniform thickness. In Examples 6 and 7, there was a portion where the fiber did not sufficiently flow to the end portion at the surface portion where the undulation of the fiber and the friction between the mold and the die were received. Moreover, a part where the fiber was not filled with the front end surface layer of the standing wall part was seen, and the layer structure of the corner part was also disordered. Except for Example 3, the tensile modulus was 46 to 47 GPa, the tensile strength was a high value of 520 to 660 MPa, and the CV value of the tensile strength was 4 to 6%, which was a small variation. On the other hand, in Example 3, as in Examples 4 and 5, the fiber exhibited good surface smoothness, the fibers were in the shape of the concavo-convex part, no wrinkles occurred, and the fiber reached the tip of the cavity of the standing wall part. And a standing wall having a desired height was formed. Also, the layer structure was maintained at the corners of the standing wall, and no fiber tension was observed. However, the tensile strength was 440 MPa, which was a low value compared to Example 1 and Examples 4-7.

(Examples 8 to 13) [Comparison of cutting angles (Table 2)]
A fiber reinforced plastic having a concavo-convex portion and a standing wall shape was obtained in the same manner as in Example 1 except that the angle formed by the notch and the fiber direction was changed. In Example 8, the cutting angle Θ is 1 °, Example 9 is 2 °, Example 10 is 5 °, Example 11 is 15 °, Example 12 is 25 °, and Example 13 is continuous in the direction of 45 °. Cuts were made.

  The obtained fiber reinforced plastic exhibited good surface smoothness in Examples 9 to 12, and the fibers were in the shape of the concavo-convex portion, and no wrinkles were generated. Further, the fiber was filled up to the tip of the cavity of the standing wall portion, and the standing wall having a desired height was formed. When the standing wall portion of the fiber reinforced plastic was cut out and the cross section was observed, the layer structure was maintained even at the corner portion of the standing wall, and no fiber tension was observed. In addition, the layer structure up to the leading end of the standing wall was continuous, and the layer composed of fibers arranged in the same direction as the stretching direction was not interrupted and maintained a uniform thickness. The tensile modulus was 46 to 47 GPa, the tensile strength was as high as 480 to 660 MPa, and the CV value of the tensile strength was as small as 3 to 6%. Particularly, in Examples 9 and 10 having a small cutting angle, a tensile strength of 600 MPa or more was expressed. About Example 8, since the cut angle is small, the interval between the cuts is as small as about 0.5 mm, it is difficult to stably cut the base material, and the CV value of the tensile strength is also 10%. Although the variation was large, the tensile modulus was 46 GPa and the tensile strength was 650 MPa. In Example 13, although the tensile strength was a little low at 360 MPa, the tensile modulus was 45 GPa, which was almost the same as that in the other examples, there was no fiber undulation, and the fiber flowed evenly to its end. It was.

Examples 14 to 18 [Comparison of Projection Length Ws (Table 3)]
In the cutting pattern of Example 2, a fiber reinforced plastic having an uneven portion and a standing wall shape was obtained in the same manner as in Example 2 except that the length of the cutting and the interval between the cuttings were changed. In Example 14, the projection length Ws and the notch interval were both 0.02 mm, Example 15 was 0.17 mm, Example 16 was 1 mm, Example 17 was 2 mm, and Example 18 was 10 mm. The actual cut lengths are 0.12 mm in Example 14, 1 mm in Example 15, 5.8 mm in Example 16, 11.5 mm in Example 17, and 58 mm in Example 18.

  The obtained fiber reinforced plastics all exhibited good surface smoothness except for Example 14, the fibers were in the shape of the concavo-convex portions, and no wrinkles were generated. Further, the fiber was filled up to the tip of the cavity of the standing wall portion, and the standing wall having a desired height was formed. When the standing wall portion of the fiber reinforced plastic was cut out and the cross section was observed, the layer structure was maintained even at the corner portion of the standing wall, and no fiber tension was observed. In addition, the layer structure up to the leading end of the standing wall was continuous, and the layer composed of fibers arranged in the same direction as the stretching direction was not interrupted and maintained a uniform thickness. Also, the tensile strength was very high at 550 to 680 MPa. In particular, the smaller the projection length Ws (cutting length), the higher the strength, but it was confirmed that this tendency appears remarkably when Ws is 1.5 mm or less. For Example 14, the fibers were in the shape of the concavo-convex part, and the layer structure of the standing wall corners was maintained, but some of the outermost fibers were not cut by fiber escape, There was a portion where the fibers swelled and a part of the tip of the standing wall was not filled with the fibers. Further, although the CV value was slightly high as 11% and the variation was large, the tensile strength showed the highest value of 690 MPa.

(Examples 19 to 22) [Comparison of fiber volume content (Table 4)]
The fiber reinforcement which has an uneven | corrugated | grooved part and a standing wall shape similarly to Example 1 except having changed the volume content Vf of the carbon fiber by changing the carbon fiber weight per unit area of the prepreg base material of Example 1. Got plastic. Respectively, in Examples 19 carbon fiber is per unit area weight is 158 g ^/ m 2, Vf is 70%, Example 20 is 146 g ^/ m 2, Vf is 65%, Example 21 is 101g ^/ m 2, Vf 45 %, Example 22 was 90 g / m ² , and Vf was 40%.

  In Example 20, the obtained fiber reinforced plastic had a portion where the fiber did not sufficiently flow to the end at the surface portion where the undulation of the fiber and the friction between the mold and the die were received. In addition, the layer structure at the corner of the standing wall was partially disturbed. On the other hand, in the fiber reinforced plastic obtained in Example 21, the fibers did not swell, and the fibers sufficiently flowed to the ends. In addition, both fiber reinforced plastics have no warp, and there is almost no portion where the reinforcing fibers are not present and the reinforcing fibers in the adjacent layer are not present in the cut portion of the outermost layer, and the appearance quality is smooth and smooth. I kept the sex. Further, the fiber was filled up to the tip of the cavity of the standing wall portion, and the standing wall having a desired height was formed. The tensile modulus was 40 to 53 GPa, the tensile strength was as high as 480 to 620 MPa, and the CV value of the tensile strength was also as small as 6 to 7%. On the other hand, in the fiber reinforced plastic obtained in Example 19, the fibers swelled, and the fibers did not flow to the end at the surface portion that received friction with the mold. The surface portion had resin chipping, the appearance quality was poor, and warping occurred. Further, there was a portion where the fiber was not filled at the tip of the standing wall, and the layer structure of the corner portion was partially disturbed near the surface layer. However, the tensile strength was 640 MPa, the elastic modulus was 54 GPa, and very good physical properties were expressed. In Example 22, the tensile modulus of elasticity was 37 GPa and the tensile strength was 450 MPa, which was considerably lower than those in Examples 1 and 20, but the obtained fiber-reinforced plastic had no warp and had good appearance quality. , Kept smoothness. As Vf increased, the tensile modulus and strength were improved. However, when Vf was too large, there was a problem that the fluidity decreased.

(Examples 23 to 25) [Comparison of thickness of thin portion (Table 5)]
The uneven portion and the standing wall shape are the same as in Example 1 except that the thickness of the thin portion of the laminate is changed by changing the number of layers of each dimension of the cut prepreg base material cut out in four sizes. A fiber reinforced plastic having was obtained. In Example 27, three layers of a substrate having a size of 224 × 174 mm, three layers of a substrate having a size of 216 × 166 mm, two layers of a substrate having a size of 208 × 158 mm, and a size of 195 × 145 mm 8 layers, Example 28 has 4 layers of 224 × 174 mm, 216 × 166 mm has 4 layers, 208 × 158 mm has 3 layers, 195 × 145 mm has 5 layers of substrate, Example 29 has 224 5 layers of base material with a size of 174 mm, 4 layers of base material with a size of 216 x 166 mm, 4 layers of base material with a size of 208 x 158 mm, 3 layers of base material with a size of 195 x 145 mm It was. In addition, when the thickness of the thin portion is formed as described above, when the thickness of the laminate is gradually changed and the thin portion is formed, the thickness of the thickest portion is the thickness of the thin portion, as described above. Example 27 is 1 mm (50% of cavity thickness), Example 28 is 1.38 mm (68.8% of cavity thickness), and Example 29 is 1.625 mm (81.3% of cavity thickness).

  In Example 28, the obtained fiber reinforced plastic exhibited good surface smoothness, the fibers were along the shape of the uneven portion, and no wrinkles were generated. Further, the fiber was filled up to the tip of the cavity of the standing wall portion, and the standing wall having a desired height was formed. When the standing wall portion of the fiber reinforced plastic was cut out and the cross section was observed, the layer structure was maintained even at the corner portion of the standing wall, and no fiber tension was observed. In addition, the layer structure up to the leading end of the standing wall was continuous, and the layer composed of fibers arranged in the same direction as the stretching direction was not interrupted and maintained a uniform thickness. On the other hand, in Example 27, although the layer structure at the corner of the standing wall was maintained, there was a portion that was not filled with fibers in the surface layer at the tip of the standing wall. Further, in Example 29, when placing in the mold, the thin wall portion was bent so as to be along the mold. The layer structure was partially disturbed. Moreover, the mold convex part and the base material were rubbed at the same place at the time of molding, and the fiber orientation on the surface was disturbed. However, in all cases, the tensile modulus was 46 to 47 GPa, the tensile strength was 570 to 590 MPa, which was almost the same value as in Example 1, and the CV value was also 5 to 6%, showing little variation.

(Example 26) [Comparison of thin wall forming method]
The cut prepreg base material was cut into two types of 224 x 174 mm and 195 x 145 mm, and two laminate precursors were prepared by laminating six layers of the base material with a size of 224 x 174 mm. A base with a size of 195 x 145 mm One laminate precursor 33 in which four layers of materials are laminated is prepared, and as shown in FIG. 15b), a laminate precursor in which four layers of a substrate having a size of 195 × 145 mm are laminated is a base having a size of 224 × 174 mm. A fiber reinforced plastic having a concavo-convex portion and a standing wall shape was obtained in the same manner as in Example 1 except that a laminate having a thin portion was prepared by sandwiching a laminate of six layers of materials. The width Wb of the thin-walled portion of this laminate is 12 mm (30% of the height of other standing walls), and the thickness of the thickest portion of the thin-walled portion woven into the cavity region is 1.5 mm (of the thickness of the cavity). 75%).

  The obtained fiber reinforced plastic exhibited good surface smoothness, the fibers were along the shape of the concavo-convex portion, and no wrinkles were generated. Further, the fiber was filled up to the tip of the cavity of the standing wall portion, and the standing wall having a desired height was formed. When the standing wall portion of the fiber reinforced plastic was cut out and the cross section was observed, the layer structure was maintained even at the corner portion of the standing wall, and no fiber tension was observed. In addition, the layer structure up to the leading end of the standing wall was continuous, and the layer composed of fibers arranged in the same direction as the stretching direction was not interrupted and maintained a uniform thickness. Further, the tensile elastic modulus was 46%, and the tensile strength was 580 MPa, which was almost the same value as in Example 1.

(Comparative Example 1) [Comparison with continuous fiber prepreg base material]
A fiber reinforced plastic having a concavo-convex portion and a standing wall shape was obtained in the same manner as in Example 1 except that the prepreg base material was not cut.

  The resulting fiber reinforced plastic has irregularities formed, but because the reinforced fibers and matrix resin were drawn into the irregularities, the ends of the fiber reinforced plastic were missing, and the fibers bridged at the edges of the irregularities. The part was resin-rich. In addition, wrinkles occurred in the flat part and almost no fiber was filled in the standing wall part, so it seemed impossible to apply as a product.

(Comparative Example 2) [Comparison with SMC]
Example 1 except that a unidirectional prepreg base material was cut into a fiber length of 25 mm and a width of 5 mm to obtain a chopped raw material prepreg, and the chopped raw material prepreg was pressed with a nip roll while being randomly oriented and bonded to each other. Similarly, a fiber reinforced plastic having an uneven portion and a standing wall shape was obtained.

  The obtained fiber reinforced plastic had fibers along the shape of the concavo-convex part, no wrinkles, and the fiber was filled up to the tip of the rib part, but because the flow state was not uniform, the difference in linear expansion coefficient Sled. Further, the tensile strength was 190 MPa, which was significantly lower than in each example, and the CV value was also 13%, showing a large variation.

(Comparative Example 3) [Comparison with a laminate having no thin portion]
When producing a laminate, a 224 × 174 mm cut prepreg base material is laminated in a 16-layer pseudo-isotropic _{manner to be} [−45 / 0 / + 45/90] _{2S, and} the cut prepreg base material to be laminated is 1 A fiber reinforced plastic having a concavo-convex part and a standing wall shape was obtained in the same manner as in Example 1 except that a laminate having no thin part having a uniform thickness was used.

  When placing the laminated body in the mold, it was attempted to follow the mold, but it was difficult to bend the laminated body and could not be completely applied. In addition, wrinkles entered the corners of the surface layer on the side in contact with the mold protrusions when bent, and the mold protrusions and the substrate were rubbed at the same location during molding, thereby disturbing the fiber orientation on the surface. Further, when the mold was clamped, the mold convex part hit the end of the laminate and the surface layer was slightly peeled off, so it seemed impossible to apply as a product.

(Comparative Examples 4 and 5) [Comparison with a laminate having a projected area of the opening of the mold recess or less]
A fiber reinforced plastic having a concavo-convex portion and a standing wall shape was obtained in the same manner as in Example 1 except that a laminate in which the area of the layer in contact with the mold recess was less than the projected area of the opening of the mold recess was used. . In Comparative Example 4, when the same laminate as in Example 1 was placed in the mold, the surface layer of 195 × 145 mm was placed in contact with the mold recess. At this time, the thin wall portion at the end portion was arranged so as to be along the mold recess. In Comparative Example 5, a 195 × 145 mm cut prepreg base material was laminated in a 16-layer pseudo-isotropic _{manner to be} [−45 / 0 / + 45/90] _{2S, and} the cut prepreg base material to be laminated was one type, The laminated body which does not have a thin part with uniform thickness was arrange | positioned.

  In Comparative Example 4, the flat plate portion of the mold exhibited good surface smoothness, the fibers were along the shape of the concavo-convex portion, and no wrinkles were generated. However, for the standing wall portion, the fiber was filled up to the tip of the cavity, but the flow of the fiber was disturbed around the corner portion of the standing wall, the layer structure was broken, and the fiber orientation of the surface layer was also disturbed. Further, in Comparative Example 5, the surface of the mold has good surface smoothness, the fibers are along the shape of the concavo-convex portion, and no wrinkles are generated, but the cavities are not flat at the tip of the cavity of the standing wall portion. There were places where the partial fibers were not filled, the fiber flow was disturbed at the corners of the standing wall, the layer structure was broken, and the fiber orientation of the surface layer was also disturbed.

(Comparative Example 6) [Comparison with the case where the thin-walled portion is not aligned when the laminate is placed in the mold]
When arranging the laminated body in the mold, the concave and convex portions and the standing wall shape are the same as in Example 1 except that the laminated body is arranged so as not to be arranged along the mold and close the opening of the concave portion of the mold. A fiber reinforced plastic having was obtained.

  The obtained fiber reinforced plastic exhibited good surface smoothness at the flat plate portion of the mold, the fibers were along the shape of the concavo-convex portion, and no wrinkles were generated. However, with respect to the standing wall portion, the position was slightly shifted when the mold convex portion contacted the laminate during pressing, and a portion where the fiber was not filled at the tip of the cavity was observed. Further, the surface layer in contact with the mold recess of the laminate of the standing walls was rubbed into the mold recess during pressing, and the fiber orientation on the surface was disturbed.

  As a use of the fiber reinforced plastic molded using the laminate obtained by the production method of the present invention, strength, rigidity, light weight is required, sports equipment such as bicycle equipment, golf shaft and head, There are automotive parts such as doors and seat frames, mechanical parts such as robot arms, and aircraft parts such as stiffener parts. In particular, the present invention can be preferably applied to automobile parts such as a seat panel and a seat frame that require a molding followability of a complicated shape in addition to strength and light weight.

It is a schematic enlarged view of the laminated body plane in this invention. It is the schematic of the shaping | molding die which has a recessed part and the convex part corresponding to this recessed part in this invention, and a cavity is comprised between the said recessed part and the said convex part. It is the schematic which shows an example of the laminated body which has a thin part in this invention, and its sectional drawing. It is the schematic which shows an example of the arrangement | positioning method to the shaping | molding die of the laminated body in this invention. It is the schematic which shows the mode of the flow of the fiber in this invention. It is the schematic which shows an example (a) of the arrangement | positioning method to the shaping | molding die of the laminated body in this invention, and the mode (b) of the flow of a fiber. It is the schematic which shows the mode (a) of the resin reservoir in this invention, and disorder (b) of the layer structure at the time of a press. It is a schematic plan view which shows an example of the cutting pattern of the cutting prepreg base material used for the prepreg laminated base material of this invention. It is an enlarged plan view which shows an example of the cutting pattern of the cutting prepreg base material used for the prepreg laminated base material of this invention. It is a schematic plan view which shows an example of the cutting pattern of the cutting prepreg base material used for the prepreg laminated base material of this invention. It is a schematic plan view which shows an example of the cutting pattern of the cutting prepreg base material used for the prepreg laminated base material of this invention. It is a top view and a sectional view showing an example of a layered product for comparison and fiber reinforced plastic. It is the top view and sectional view which show an example of the lamination substrate of the present invention, and fiber reinforced plastics. It is a top view which shows an example of the laminated base material of this invention, and a fiber reinforced plastic. It is the schematic which shows an example of the laminated body which has a thin part in this invention, and its sectional drawing. It is the top view (a) and sectional drawing (b) of the metal mold | die which concern on one embodiment of this invention. It is the schematic which shows an example of the manufacturing method of the cutting prepreg base material in this invention. It is the schematic which shows an example of the manufacturing method of the cutting prepreg base material in this invention.

Explanation of symbols

1: Reinforcing fiber 2: Notched prepreg base material 3 (3a, 3b): Notched 4: Mold mold convex part 5: Mold mold concave part 6: Cavity formed between convex part and concave part of mold 7: Molding Shape formed by mold end (standing wall)
8: Thickness of cavity 9: Opening portion of molding die recess 9 ': Projected area of opening of molding die recess 10: Thin portion 10': Region A (thin portion)
10 ": Region B (thin portion)
11: Layer in contact with mold recess of laminate 12: Layer structure 13: Disorder of layer structure 14: End of mold 15: Resin reservoir 16: End of laminate 17: Fiber orientation direction 18: Fiber orthogonal direction 19 : Cutting angle Θ
20: Projection length Ws obtained by projecting the cut in the vertical direction of the reinforcing fiber
21: Fiber length L (interval between cuts)
22: Laminate of cut prepreg base material 23: Fiber reinforced plastic 24: Short fiber layer 25: Cut opening 26: Fiber bundle end portion 27: Adjacent layer 28: Resin rich portion 29: Layer waviness 30: Reinforced fiber Rotation 31: Laminate having thin portion 32: Thickness of thin portion 33: Laminate precursor 34: Width Wa of region A
35: width Wb of region B
36: Sum of the thickest portions in the region B 36 ', 36 ": Thickness of the thickest portion of the portion gradually changing toward both surface layers 37: Layer in contact with the mold of the laminate (laminate both surfaces)
38: Central layer of laminated body 39: Fiber reinforced plastic molding die 40: Concavity and convexity 41: Standing wall portion 42: Upper die 43: Lower die 44: Rotating blade roller

Claims (6)

After a prepreg base material composed of reinforced fibers and matrix resin oriented in one direction is cut into a predetermined shape, the fiber direction of the prepreg base material is aligned in at least two directions to produce a laminate. Further, the laminate is placed in a mold having a concave portion and a convex portion corresponding to the concave portion, and a cavity is formed between the concave portion and the convex portion, and press-molded to obtain a fiber reinforced plastic. A method for producing a fiber reinforced plastic, the method comprising producing at least the following steps (1) to (3).
(1) A notch prepreg base material that has a notch on the entire surface of the prepreg base material and substantially all of the reinforcing fibers are cut by the notch, and at least a layer that is in contact with the concave part is formed of the concave part. Cut to have an area equal to or larger than the projected area of the opening, and at least part of the end of the laminate is laminated with respect to the number of laminations of the cut prepreg base material in the thickest portion of the laminate. Lamination process (2) for laminating the cut prepreg base material so as to form a thin part thinner than the thickness of the thickest part, formed by reducing the number by at least one layer or more. A step of placing the laminated body along at least part of the thin-walled portion of the laminated body along at least part of the end of the molding die; The formed laminate is molded The other type of pressing pressurizing Press-said laminate is fluidized to press molding The cut prepreg base material used in the laminating step (1) has a fiber length L of the reinforcing fibers cut by the cut of 10 to 100 mm, and a fiber volume content Vf of 45 to 65. %, The absolute value of the angle Θ formed by the cut with the reinforcing fiber is in the range of 2 to 25 °, and the projected length Ws projected in the vertical direction of the reinforcing fiber is 0.1 to The manufacturing method of the fiber reinforced plastics of Claim 1 which exists in the range of 1.5 mm. The cut prepreg base material is laminated so that the thickness of the thin portion at the end of the laminated body obtained in the laminating step (1) is 80% or less of the thickness of the cavity of the mold. The method for producing a fiber-reinforced plastic according to claim 1 or 2, wherein: In the laminating step of (1), the means for producing the laminated body cuts the prepreg base material according to a plurality of cut patterns offset toward the outer edge at at least a part of one end portion of the cut pattern. The manufacturing method of the fiber reinforced plastics in any one of Claims 1-3 which laminates the said some prepreg base material and obtains the said laminated body which has a thin part. In the laminating step (1), the cut pattern of the prepreg base material constituting the central layer other than both surface layers of the laminate is made smaller than the cut pattern of the prepreg base material constituting both surface layers of the laminate. And the manufacturing method of the fiber reinforced plastics in any one of Claims 1-3 which integrates the said prepreg base material and obtains the said laminated body which has a thin part. The method for producing a fiber reinforced plastic according to any one of claims 1 to 5, wherein in the pressing step (3), at least a part of an outer edge of the laminate is stretched to form a fiber reinforced plastic having a standing wall. .

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