JP5353099B2 - Manufacturing method of fiber reinforced plastic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a fiber reinforced resin, which has favorable fluidity and molding following-up properties to a complicated shape and reveals excellent mechanical characteristics and its low scattering characteristics and an excellent dimensional stability when being employed as the fiber reinforced resin. <P>SOLUTION: This method for manufacturing the fiber reinforced resin comprises at least (a) an incision inserting process for producing a short fiber group 4 by inserting a plurality of intermittent incisions 2 in a prepreg base material 1 by thrusting a blanking die arranged with blades, (b) a cutting process for cutting simultaneously with or continuously to the incision inserting process the prepreg base material 1 including the short fiber group 4 into a predetermined shape, (c) a laminating process for laminating a plurality of sheets of the prepreg base materials 1 and (d) a molding process, in which the short fiber group 4 is applied to at least some part of he bent part 8 of a molding die so as to be molded along the bent part 8 of the molding die in order to mold the fiber reinforced resin 9. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention has good fluidity and molding followability at the time of molding, and when made into fiber reinforced plastic, it exhibits excellent mechanical properties applicable to structural materials, its low variation, and excellent dimensional stability. The present invention relates to a method for manufacturing fiber reinforced plastic. More specifically, for example, the present invention relates to a method for producing a fiber reinforced plastic suitably used for automobile members, sports equipment, aircraft members and the like.

  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 method for molding fiber reinforced plastic, a semi-cured intermediate base material impregnated with a thermosetting resin is laminated on a continuous reinforcing fiber called a prepreg base material, and heat is applied by heating and pressurizing with a high-temperature high-pressure kettle. Autoclave molding in which a curable resin is cured and a fiber-reinforced plastic is molded is most commonly performed. In recent years, for the purpose of improving production efficiency, RTM (resin transfer molding) molding in which a continuous fiber base previously shaped into a member shape is impregnated with a thermosetting resin and cured has been performed. The fiber reinforced plastics obtained by these molding methods have excellent mechanical properties because they are 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, there is a problem that it is difficult to form a three-dimensional shape because it is a continuous fiber.

  This problem was more serious especially in the case of complex three-dimensional shapes. If you imagine a sheet that is difficult to cause shear deformation in a plane, such as paper, in a complicated three-dimensional shape, it is easy to understand. However, when such a continuous fiber substrate is shaped, the surface of the shape cannot be covered. However, since wrinkles are generated at the place where the base material is left, high-quality shaping is difficult. Even if it is a continuous fiber base material, if it can be sheared in-plane like a woven base material, it is much easier to shape than paper etc., but if the shape becomes complicated, fiber tension and There was a problem that wrinkles would occur.

  For example, if a prepreg base material in which bundled discontinuous fibers are mixed and dispersed with a thermosetting resin or a thermoplastic resin such as BMC (bulk molding compound), SMC (sheet molding compound) or stampable sheet, Although it has been found that the three-dimensional shape having a shape follows the molding, it has a problem that it cannot be applied to a structural member because of its low mechanical characteristics.

In order to fill the drawbacks of the above-described materials, a base material that can flow and reduce variations in mechanical properties by cutting into a prepreg composed 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. Furthermore, since it has a structure including a notch defect compared to a continuous fiber base material, the notch that is a stress concentration point becomes a starting point of fracture, and in particular, there is a problem that tensile strength and tensile fatigue strength are lowered. there were.
Japanese Unexamined Patent Publication No. 63-247010 Japanese Patent Laid-Open No. 9-254227

  In view of the background of such prior art, the present invention has good fluidity, molding followability of complex shapes, and excellent mechanical properties applicable to structural materials when it is used as a fiber reinforced plastic, and its low variability. Another object of the present invention is to provide a method for producing a fiber reinforced plastic that exhibits excellent dimensional stability.

  The present invention employs the following means in order to solve such problems. That is, a method for producing a fiber-reinforced plastic by press-molding a laminate of a prepreg base material composed of reinforcing fibers and a matrix resin aligned in one direction, and obtaining a fiber-reinforced plastic having a three-dimensional curved surface, It is a manufacturing method of fiber reinforced plastic which forms fiber reinforced plastic through the following processes (1) to (4).

(1) A plurality of intermittent or continuous cuts are inserted into a prepreg base material by pressing a die having a blade disposed thereon, and at least some of the reinforcing fibers are cut into a length of 10 to 100 mm and short. Incision insertion step for forming a fiber group, where the angle between the incision and the reinforcing fiber is Θ, the absolute value of Θ is in the range of 2 to 25 ° ( incision insertion step ( 2) A cutting step of cutting out the prepreg base material including the short fiber group into a predetermined shape at the same time as or in succession to the cutting insertion step of (1) above, and using the cut prepreg base material as the cut prepreg base material. (3) Lamination step of laminating a plurality of sheets to obtain a prepreg laminate (4) When the laminate is placed on a mold, the laminate is pressed against the mold and cured or solidified, and a fiber-reinforced plastic is molded, At least part of the bending part of the mold Serial Ategai short fiber group, the molding step be along the bent portion of the mold.

  According to the present invention, it has good fluidity, molding conformability of complex shapes, and when it is made of fiber reinforced plastic, it has excellent mechanical properties applicable to structural materials, its low variation, and excellent dimensional stability. Can be obtained.

  The present inventors have good fluidity, molding conformability of complex shapes, and when made into fiber reinforced plastic, exhibit excellent mechanical properties, its low variation, and excellent dimensional stability, fiber reinforced For the plastic manufacturing method, we studied diligently and used a prepreg base material with a specific notch pattern inserted into a specific base material called a prepreg base material composed of carbon fibers and matrix resin aligned in one direction. In the laminate in which the cut prepreg base material is laminated in a flat plate shape, by pressing and stretching a region composed only of reinforcing fibers having a fiber length within a specific range by cutting, a fiber reinforced plastic is molded, They sought to solve this problem all at once.

  In addition, the manufacturing method of this invention makes object the fiber reinforced plastic which has a three-dimensional curved surface. A part of the fiber reinforced plastic may have ribs or bosses. In the present specification, unless otherwise specified, in the term including fibers or fibers (for example, “fiber direction”), the fibers represent reinforcing fibers. In the present specification, the continuous fiber refers to a reinforcing fiber having a fiber length of 100 mm or more. The prepreg base material used in the present invention is a state in which the resin sheet is not completely impregnated between the fibers, in addition to the reinforcing fiber aligned in one direction and the base material in which the reinforcing fiber base material is completely impregnated with resin. And a resin semi-impregnated base material (semi-preg: hereinafter also referred to as semi-impregnated prepreg).

  The molding method of the present invention will be described with reference to FIG. In forming a fiber reinforced plastic having a three-dimensional curved surface, when forming using a continuous fiber base material, a flat cut pattern in which the surface shape of the fiber reinforced plastic is developed is created, and continuous cut by the cut pattern. It is necessary to shape the fiber base material along the mold and repeat it for the number of layers to produce a laminate. If a simple prepreg laminate is placed in a mold and molding is performed without following such a procedure, as shown in FIG. 16 (a), the fibers are stretched and the base material does not stretch. There arises a problem that the base material unfilled portion is formed at the end portion, or that the wrinkles and the resin rich portion 25 are formed in the R portion of the molded product. On the other hand, in the case of molding using the cut prepreg base material according to the present invention, the discontinuous portion extends and follows a complicated shape, so that it is not necessary to form a complicated cut pattern. Because it is not necessary to form it in line with the shape of the fiber reinforced plastic) (that is, it may be shaped to the approximate shape of the fiber reinforced plastic after molding), Therefore, fiber-reinforced plastic can be manufactured with extremely high efficiency. As a result, as shown in FIG. 16B, it is possible to obtain a fiber reinforced plastic having no base material unfilled portion and resin rich portion.

  In the fiber reinforced plastic manufacturing method of the present invention, (a) a cutting insertion step of obtaining a cutting prepreg base material by inserting a cut into the prepreg base material, and (b) a cutting prepreg base material into a target shape. Cutting process for cutting out, (c) Laminating process for stacking a plurality of cut prepreg substrates after cutting, and obtaining a prepreg laminated body, (d) Molding process for placing the prepreg laminated body in a mold and solidifying the matrix resin , Through at least four steps (a) to (d). The flow of the four steps in the present invention is shown in FIG.

In the cutting insertion step (a), a die having a blade is pressed against a prepreg base material composed of reinforcing fibers and a matrix resin (thermosetting resin or thermoplastic resin) aligned in one direction. Thus, a plurality of intermittent or continuous cuts are inserted, and at least some of the reinforcing fibers are divided into short fiber groups each having a length of 10 to 100 mm. The longer the reinforcing fiber contained in the prepreg base material, the better the mechanical properties. However, the reinforcing fiber is stretched at the time of molding, and it is difficult to stretch in the fiber orientation direction. Therefore, in the case of a prepreg base material, when the fibers are oriented in the direction to be stretched, by inserting a cut and making some reinforcing fibers in the prepreg base material into short fibers, the fiber orientation direction is also obtained. It becomes possible to expand. (Hereinafter, the prepreg base material including the short fiber group is referred to as a cut prepreg base material.)
As typical methods for inserting intermittent cuts in the prepreg substrate, the following three methods are conceivable. The first is to insert a cut manually using a single blade such as a cutter knife, or an automatic cutting machine (moving the single blade or round blade according to the specified CAD drawing, Is a cutter method in which a notch is inserted into a prepreg base material using a cutting device. Unlike the punching method and rotary blade method described later, the cutter method does not require a punching die and can flexibly cope with pattern changes. Further, since many automatic cutters used for general purposes have a large size of several m square, the board is effective as a means for preparing a base material for forming a large member. However, as the number of cuts increases, the time taken to insert the cuts becomes longer, so it is difficult to say that this is a mass production method. The second is a punching method in which a cut is inserted into the prepreg base material by intermittently pressing a punching die having a blade disposed on the prepreg base material using a press machine (elevator).

  In FIG. 2, an example of the manufacturing method of the cut prepreg base material by the punching method is shown. The punching method has a high production efficiency such that a large amount of cuts can be inserted into the prepreg substrate at a time by a single press, and punching is easy. The third is a rotary blade method that inserts a cut into a prepreg base material by continuously pressing the prepreg base material against a rotary blade in which a blade is previously arranged.

  In FIG. 3, an example of the manufacturing method of the cutting prepreg base material by a rotary blade method is shown. The rotary blade method is advantageous in that it is possible to insert a cut continuously even when compared with the cutter method and the punching method described above, and the cutting insertion speed can be set faster. In the present invention, any of the above-described methods may be used as means for inserting the incision, but in view of mass productivity, it is preferable to use either the punching method or the rotary blade method.

  In the cutting step (b), the cut prepreg prepreg base material is cut out simultaneously or continuously with the cutting insertion step (hereinafter, the cut prepreg base material may be referred to as a cut prepreg base material). In the manufacturing method of the present invention, the variation in strength and appearance quality of the fiber reinforced plastic that can obtain the positional accuracy of the cut is controlled. In the conventional technology, since the cutting insertion process and the cutting process are independent, the relative position between the outer edge of the cut prepreg base material and the cut varies, resulting in variations in strength and appearance when using fiber reinforced plastic. Was getting bigger. In the present invention, by performing the cutting insertion step and the cutting step simultaneously or sequentially, it is possible to produce a cut prepreg base material with high accuracy with respect to the cut inserted in the prepreg base material. Become. In the present invention, “continuously with the cutting insertion process” means that the apparatus for feeding the prepreg base material is the same in the cutting insertion process and the cutting process.

  Any of the above-described cutter method, punching method, and rotary blade method may be used as means for specifically performing the cutting. FIG. 2 shows an example in which the punching method is used in both the cutting insertion process and the cutting process, and FIG. 3 shows an example in which the rotary blade method is used in both the cutting insertion process and the cutting process. . Moreover, it is preferable to perform a cutting process after a cutting insertion process. If the order is reversed, the cut prepreg base material is not gripped around, and the base material moves during insertion of the cut, making it difficult to insert the cut at the intended position.

  The fiber length L of the short fiber group included in the cut-out prepreg substrate according to the present invention is preferably in the range of 10 to 100 mm. By setting the fiber length L of the short fiber group to 100 mm or less, the portion can flow at the time of molding, in particular, it can also flow in the fiber orientation direction, and has excellent shape followability to a complicated shape. When there is no short fiber group, that is, when only continuous fibers are used, a complicated shape cannot be formed because the fibers do not flow in the fiber orientation direction. In addition, when the fiber length L is less than 10 mm, the fluidity is further improved, but high mechanical properties necessary as a structural material cannot be obtained even if other requirements are satisfied. Considering the relationship between fluidity and mechanical properties, it is more preferably in the range of 20 to 60 mm. Depending on the cutting pattern, fibers with a fiber length of 10 mm or less may be formed in part, but the fewer the fibers with a fiber length of 10 mm, the better. More preferably, the area in which fibers of 10 mm or less are oriented is smaller than 20% of the proportion of the short fiber group.

  In the lamination step (c), a plurality of the cut prepreg base materials are laminated to obtain a prepreg laminate. At this time, a plurality of cut prepreg base materials are laminated so that the fiber directions are aligned in at least two directions and integrated so that at least a part of the cut prepreg base material including the short fiber group is included. Is preferred. By orienting in two or more directions, a fiber reinforced plastic having low anisotropy of fluidity and mechanical properties can be obtained. Further, for example, hybrid lamination may be performed by using a prepreg base material including the short fiber group and a prepreg base material that is a unidirectional base material or a woven base material without cutting.

  In the molding step (d), the prepreg laminate is placed in a heated mold and heated under pressure (in the case of a thermoplastic resin), or placed in a heated mold and cooled under pressure (in the case of a thermoplastic resin). ) To solidify the resin into fiber-reinforced plastic. Only when the resin is cured or solidified to obtain a fiber-reinforced plastic can it be used as a member that is lightweight but has high strength and high rigidity. Examples of the method for solidifying the resin, that is, the method for molding the fiber reinforced plastic include press molding, VaRTM molding, autoclave molding, sheet winding molding, and the like. Among these, press molding is preferable in consideration of production efficiency.

  In the molding step (d), the laminate is placed on a mold, and the laminate is pressed against the mold to be cured or solidified, and the fiber-reinforced plastic is bent. The short fiber group is assigned to at least a part of the portion. By applying the short fiber group to the bent portion of the mold and pressing it against the mold, the laminate can be made to follow a three-dimensional curved surface. The manufacturing method of the present invention can be applied when the shape is a smooth surface or a gently curved surface, but in addition, a three-dimensionally having a rib or a standing surface in a part of the shape. When molding a complicated member, the merit of using the manufacturing method of the present invention is great. If the laminated body of continuous fiber prepreg base material is heated and pressed and a member including a standing surface or a rib shape is simply press-molded, the fibers cannot conform to the shape of the mold, or the mold Fibers are not filled up to the end of the cavity, and it is very difficult to obtain a molded article of good quality. As in the present invention, if a prepreg base material containing a short fiber group is used, even if it is a member including a standing surface or a rib shape, the base material easily exhibits good fluidity during press molding. It is possible to obtain a molded article of a high quality.

  As a molding method according to the present invention, it is preferable that the mold is heated to a temperature higher than that of the laminate, and the laminate is pressed against the mold to cure or solidify the resin. At this time, the laminated body may be placed in a mold, and the temperature of the mold may be raised to an appropriate temperature, and then the laminated body may be pressed against the mold. As the temperature of the laminate rises, the viscosity of the resin decreases temporarily, and the base material increases the fluidity. At this time, the laminated body can be made to conform to a predetermined shape by pressing the laminated body against the mold. In the case of a thermosetting resin, when the laminate is further heated thereafter, the resin is cured and a desired fiber-reinforced plastic can be obtained. On the other hand, in the case of a thermoplastic resin, the resin is solidified by lowering the temperature of the mold and then lowering the temperature of the laminate, and a desired fiber-reinforced plastic can be obtained.

  Further, when the resin is a thermoplastic resin, after heating the laminated body, it is preferable that the molding die is cooled to a temperature lower than that of the laminated body, and the laminated body is pressed against the molding die to be solidified. By placing the heated laminate in a low-temperature mold and pressing the substrate against the mold while the temperature of the laminate is high and the viscosity of the resin is low, the laminate can be made to conform to a predetermined shape. Further, by further lowering the temperature of the laminate, the resin can be solidified and a desired fiber-reinforced plastic can be obtained. In this case, since it is not necessary to raise the temperature of the mold, the molding time can be further shortened.

  Examples of reinforcing fibers used in the present invention include organic fibers such as aramid fibers, polyethylene fibers, polyparaphenylene benzoxador (PBO) fibers, glass fibers, carbon fibers, silicon carbide fibers, alumina fibers, tyrano fibers, and basalts. Examples thereof include inorganic fibers such as fibers and ceramic fibers, metal fibers such as stainless fibers and steel fibers, and other reinforcing fibers using boron fibers, natural fibers, modified natural fibers and the like as fibers. Among them, carbon fiber is particularly lightweight among these reinforcing fibers, and has particularly excellent properties in specific strength and specific modulus, and is also excellent in heat resistance and chemical resistance. It is suitable for members such as automobile panels that are desired to be made. Among these, PAN-based carbon fibers that can easily obtain high-strength carbon fibers are preferable.

  As described above, as the matrix resin used for the prepreg base material according to the present invention, either a thermosetting resin or a thermoplastic resin may be used.

  In general, when the matrix resin is a thermosetting resin, the prepreg base material has tackiness at room temperature. Therefore, it is possible to easily produce a laminate by simply stacking the base materials and integrating the base materials by adhesion. Furthermore, since a prepreg laminate composed of a thermosetting resin has excellent drapeability at room temperature, for example, when forming using a mold having a concavo-convex part, preliminary shaping along the concavo-convex part in advance is easy. Can be done. This pre-shaping improves moldability and facilitates flow control. Candidates for thermosetting resins include, for example, epoxy resins, unsaturated polyester resins, vinyl ester resins, phenol resins, epoxy acrylate resins, urethane acrylate resins, phenoxy resins, alkyd resins, urethane resins, maleimide resins, and cyanate resins. Can be mentioned. More preferably, among the thermosetting resins, an epoxy resin, an unsaturated polyester resin, a vinyl ester resin, a phenol resin, an acrylic resin, or a mixed resin thereof is preferable. The resin viscosity at normal temperature (25 ° C.) of these resins is preferably 1 × 10 6 Pa · s or less, and within this range, a prepreg base material having tackiness and draping properties satisfying the present invention is obtained. Can do. Among them, the epoxy resin is most excellent in mechanical properties as a reinforced fiber composite material obtained in combination with carbon fiber.

  On the other hand, if the matrix resin is a thermoplastic resin, generally, the time required for molding can be shortened as compared with the thermosetting resin, and the mass productivity is superior to the thermosetting resin. However, a prepreg base material using a thermoplastic resin does not have a tack property at room temperature. As a result, it becomes a fiber reinforced plastic having a large fiber orientation unevenness. In particular, when molding with a mold having an uneven portion, the difference appears remarkably. Therefore, by connecting a plurality of prepreg base materials in advance by heating / cooling treatment, etc. before putting the base material into a laminate, the base material also has good handleability. It is also possible to reduce the fiber orientation unevenness. Candidates for the thermoplastic resin used in the present invention include polyamide, polyacetal, polyacrylate, polysulfone, ABS, polyester, acrylic, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene, polypropylene, polyphenylene sulfide (PPS). ), Polyether ether ketone (PEEK), liquid crystal polymer, vinyl chloride, polytetrafluoroethylene and other fluororesins, and silicone.

  Furthermore, it is preferable that the two steps of the cutting insertion step and the cutting step are performed in the same mold as shown in FIG. Thereby, the relative position between the outer edge of the cut prepreg substrate and the cut becomes more accurate, and fiber-reinforced plastic with less variation in strength and appearance quality can be mass-produced. Further, by performing the two steps using the same punching die, it is not necessary to provide two mechanisms for cutting the base material, and the equipment cost can be greatly reduced.

In the notch insertion step, the absolute value of the angle Θ (hereinafter also referred to as the notch angle) between the notch and the reinforcing fiber needs to be in the range of 2 to 25 °. An example of the cutting pattern at this time is shown in FIG. 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, when the incision is made, the fiber easily escapes from the blade, and in order to set the fiber length L of the short fiber group to 100 mm or less, the absolute value of Θ If it 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 orientation direction at the point X and the cut is θ (X), Θ is θ (X ) Is the average value on the cut, that is, the value given by (Equation 1). Here, as shown in FIG. 6, the end points of the incision are point A and point B, the points A and B are connected, the curve along the incision is C, and the curve C at the point X is very small. The line segment is ds.

  Hereinafter, the preferable example of the cutting pattern inserted in a prepreg base material in this invention is demonstrated using FIGS.

  A plurality of controlled and aligned cuts 2 are made on a prepreg base material in which reinforcing fibers are aligned in one direction. The fibers are divided between the cuts 2 that form pairs in the fiber orientation direction, and the interval 31 is set to 10 to 100 mm, so that substantially all of the reinforcing fibers included in the short fiber group of the prepreg base material have a fiber length L. Can be 10 to 100 mm. As shown in FIG. 5, if the angle 17 between the cut and the reinforcing fiber is Θ, the absolute value of Θ is in the range of 2 to 25 ° over the entire surface. FIG. 7a) shows an example where the absolute value of Θ is greater than 90 ° and b) is greater than 25 °. However, in these examples, the high strength that can be obtained by the present invention cannot be expressed.

  FIG. 8 shows a prepreg substrate having five different cutting patterns. The cut prepreg substrate 3 in FIG. 8 a) has skewed continuous, straight cuts 2 arranged at equal intervals. The cut prepreg substrate 3 in FIG. 8b) has skewed continuous, straight cuts arranged at two different intervals. The cut prepreg substrate 3 in FIG. 8c) has continuous, curved (meandering) cuts 2 arranged at equal intervals. The cut prepreg base material 3 of FIG. 8d) has intermittent linear cuts 2 arranged at equal intervals and skewed in two different directions. The cut prepreg substrate 3 in FIG. 8e) has skewed intermittent linear cuts 2 arranged at equal intervals. The incision may be a curved line as shown in FIG. 8c), but a straight line as shown in FIGS. 8a), b), d), and e) is preferable because the flowability is easily controlled. Further, the length L of the reinforcing fiber divided by the cut may not be constant as shown in FIG. 8b), 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 2a are continuously made as shown in FIGS. 8a) to 8c). In the pattern of Example [1], since the cut 2a is not intermittent, flow disturbance does not occur in the vicinity of the cut end, and all the fiber lengths L are constant in the region where the cut 2a is inserted. The flow is stable. Since the cuts 2a are continuously made, in order to prevent the cut prepreg base material 3 from falling apart, an area where the cuts are not connected to the periphery of the cut prepreg base material is provided. The handleability can be improved by gripping with a support such as a sheet-like release paper or film without a cut.

Further, as another preferable example [2], as shown in FIG. 5, when Ws is a length 18 obtained by projecting the cut in the vertical direction of the reinforcing fiber, Ws is intermittent within a range of 30 μm to 100 mm. The notch 2b is provided on the entire surface of the notched prepreg base 3, and the notch 2b1 and the notch 2b2 adjacent to the notch 2b1 in the fiber orientation direction may have the same geometric shape. Here, the “projection length Ws projected by the cut in the vertical direction of the reinforcing fiber” is the vertical direction of the reinforcing fiber (fiber orthogonal direction 14) in the plane of the prepreg layer as shown in FIG. Is the projection plane, and refers to the length 18 when projected perpendicularly to the projection plane (fiber orientation direction 13). When Ws is 30 μm or less, it is difficult to control the cutting, and it is difficult to ensure that L is 10 to 100 mm over the entire surface of the cut prepreg substrate. That is, if there is a fiber that is not cut by cutting, the fluidity of the base material is remarkably lowered. However, if a large amount of cutting is made, there is a problem that 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. 5 shows an example in which both L and Ws are one type. Any of the cuts 2b (for example, 4b1) has another cut 2b (for example, 4b2) that overlaps by translating in the fiber direction. By having a width 19 where the fiber is divided by adjacent cuts and having a fiber length L that is shorter than the fiber length L divided by the cuts 2b that form a pair in the fiber direction, the fibers are stably The cut prepreg base material 3 can be manufactured with a length of 100 mm or less. In the pattern of Example [2], when the obtained cut prepreg base material 3 is laminated, the cut is intermittent, and thus the handleability is excellent. Although other patterns are illustrated in FIGS. 8D and 8E, 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 mm 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. In addition, when trying to insert a cut by pressing the blade against the prepreg base material, the carbon 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 features 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. 9 shows a prepreg laminate 6 in which a cut prepreg base material 3 having an absolute value of an angle Θ between the cut 2 and the fiber 16 of 90 ° is laminated, a), and the laminate 6 The molded fiber reinforced plastic 9 is shown in b) as a plan view in which the layers derived from the cut prepreg base material 3 are respectively close-up and a cross-sectional view taken along the line AA in the plan view. As shown in a), the cut prepreg base material 3 is provided with a cut perpendicular to the fiber on the entire surface, and the cut 2 penetrates the thickness direction of the layer. By setting the fiber length L to 100 mm or less, the fluidity is ensured, and the fiber reinforced plastic 13 whose area is easily extended from the laminate 6 can be obtained by press molding or the like (however, the thickness is reduced). As shown in b), when the elongated fiber reinforced plastic 13 is obtained, the short fiber layer 21 derived from the cut prepreg base material 3 extends in the direction perpendicular to the fiber and has no fiber (cut opening). 22 is generated. This is because the reinforcing fibers generally do not expand at a pressure of the molding level. In the case of FIG. 9, the cut opening 22 is generated for the extended length, for example, from the prepreg laminate 6 of 250 × 250 mm. When the fiber reinforced plastic 9 having a size of 300 × 300 mm is obtained, the total area of the cut openings 22 is 50 × 300 mm, that is, 1/6 (about 16. 7%) is a cut opening. As shown in the cross-sectional view, this region 22 is occupied by the substantially triangular resin-rich portion 25 and the region where the adjacent layer has intruded, as the adjacent layer 23 has intruded. Therefore, when the prepreg laminate 6 using the cut prepreg base material 3 is stretched and formed, the undulation 26 of the layer and the resin rich portion 25 are generated at the fiber bundle end portion 24, which causes deterioration of mechanical properties and surface quality. Will affect the 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 9 is in-plane anisotropic, and design is difficult due to problems such as warping. Further, in terms of strength, the fiber oriented to about ± 10 ° or less from the load direction transmits most of the load, but the fiber bundle end 24 must redistribute the load to the adjacent layer 23. Don't be. At that time, as shown in FIG. 9b), when the fiber bundle end 24 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. 10 shows a laminate 6 in which the cut prepreg base material 3 of the preferred example [1] of the present invention is laminated in a), and a fiber reinforced plastic 9 in which the laminate 6 is molded in b). The top view which closed the layer derived from the embedded prepreg base material 3, and the sectional view which cut out the AA cross section of the top view were shown. As shown in a), the incision prepreg base material 3 is provided with continuous incisions 2a having an absolute value of an angle Θ between the fibers 16 of 25 ° or less on the entire surface, and the incisions 2a indicate 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 9 whose area is easily extended from the laminate 6 can be obtained by press molding or the like. When the stretched fiber reinforced plastic 9 is obtained as in b), the short fiber layer 21 derived from the cut prepreg base material 3 stretches in the direction perpendicular to the fiber, and the fiber 16 itself rotates 27 to expand the stretched region. In order to increase the area, a region (cut opening) 22 in which no fiber exists as shown in FIG. 9 is not substantially generated, and the area on the surface of the layer of the cut opening is 0. 0 compared to the surface area of the layer. It is in the range of 1 to 10%. Therefore, as can be seen from the cross-sectional view, the adjacent layer 23 does not enter, and a high-strength and high-quality fiber-reinforced plastic 9 having no layer waviness or resin-rich portion can be obtained. Since the fibers 16 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. Further, in terms of strength, when attention is paid to the fibers oriented to about ± 10 ° or less from the load direction in the same manner as described above, the fiber bundle end portion 24 lies down with respect to the load direction as shown in FIG. I can see the situation. Since the fiber bundle end portion 24 is slanted in the layer thickness direction, the load is smoothly transmitted, and peeling from the fiber bundle end portion 24 hardly occurs. Therefore, a marked improvement in strength is expected compared to FIG. The fiber bundle end 24 is inclined in the layer thickness direction because when the above-mentioned fiber rotates, there is a gentle distribution in the rotation 27 of the fiber 16 from the upper surface to the lower surface due to friction between the upper surface and the lower surface. It is considered that the existence distribution of the fibers 16 occurs in the layer thickness direction, and the fiber bundle end portion 24 is inclined in the layer thickness direction. In such a layer of the fiber reinforced plastic 9, 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 16 of the cut 2a is 25 It can be obtained for the first time when it is below °.

  In FIG. 11, the laminated body 6 in which the cut prepreg base material 3 of the preferred example [2] of the present invention is laminated is shown in a), and the fiber reinforced plastic 9 in which the laminated body 6 is molded is shown in b). The top view which closed up the layer derived from the base material 3 was shown. As shown in a), the cut prepreg base material 3 is provided with intermittent cuts 2 having an absolute value of the angle Θ between the fibers 16 of 25 ° or less and the cuts 2 are in the layer thickness direction. Through. The fiber length L is set to 100 mm or less over the entire surface of the cut prepreg base material 3 by the cuts 2 to ensure fluidity, and the fiber reinforced plastic 9 whose area is easily extended from the laminate 6 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 9 is obtained as in b), the short fiber layer 21 derived from the cut prepreg base material 3 does not stretch in the fiber direction when stretched in the fiber orthogonal direction. A non-existing region (cut opening) 22 is generated, but the adjacent short fiber group flows in the direction perpendicular to the fiber, thereby filling the cut opening 22 and reducing the area of the cut opening 22. This tendency is particularly remarkable 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 22 is not substantially generated, and the cut opening The area on the surface of the layer can be in the range of 0.1 to 10% compared to the surface area of the layer. Therefore, the adjacent layer does not penetrate in the thickness direction, and a high-strength and high-quality fiber reinforced plastic 9 without layer undulation or resin-rich portion can be obtained. Since the fibers 16 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 cut opening with the flow in the direction perpendicular to the fiber to obtain a fiber reinforced plastic without layer undulation has an absolute value of the cut angle Θ of 25 ° or less, and the cut 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.

  As for the prepreg laminated body which concerns on this invention, all the layers are comprised with the cut prepreg base material, and it is good for the fiber length of all the reinforcement fibers to be in the range of 10-100 mm. By making all layers of the prepreg laminate a notched prepreg base material and substantially all reinforcing fibers short fibers, the base material can be uniformly stretched regardless of the stretching direction. In particular, when the shape to be molded is complex and the flow process of the base material cannot be easily assumed, it is possible to easily obtain a molded article of good quality by making the entire layer a cut prepreg base material. preferable. Note that “substantially all of the reinforcing fibers are divided by the incision” means that 95% or more of the number of reinforcing fibers contained in the prepreg laminate is divided to 10 to 100 mm.

  In the cut prepreg base material according to the present invention, the greater the number of cuts and the longer the cut, the lower the rigidity of the cut prepreg base material, and the easier the base material deforms. Accordingly, when the cut prepreg base material is lifted during the laminating operation, handling becomes difficult, for example, the shape of the cut prepreg base material is broken. In order to avoid such a problem, as shown in FIG. 12, the side of the prepreg base material opposite to the side against which the punching die 10 is pressed is gripped by the tape-like support 30, leaving the tape-like support 30. It is preferable to carry out a so-called half cut in which only the prepreg substrate 1 is cut as it is. Thereby, even if there is much amount of cutting, since a tape-shaped support body suppresses a deformation | transformation of a cutting prepreg base material, the handleability of a base material improves significantly. Here, the tape-like support includes papers such as kraft paper, polymer films such as polyethylene / polypropylene, metal foils such as aluminum and the like, and in order to obtain releasability from the resin, silicone. A surface or “Teflon (registered trademark)” type release agent, metal vapor deposition, or the like may be applied to the surface. At this time, the amount of the blade tip 28 entering the prepreg base material 1 may be the depth at which the blade tip 28 enters just the depth at which the prepreg base material 1 is cut. When the blade 11 is worn by cutting, there is a possibility that uncut portions frequently occur. Therefore, it is preferable that the blade penetrates the prepreg base material 1 and enters only a part of the tape-shaped support 30. Furthermore, as the thickness of the tape-shaped support body 30, if the thickness is large, the material cost increases, which is not economical. However, if the thickness is too thin, it becomes difficult to keep the tip 28 of the blade inside the tape-shaped support 30 when the punching die 10 is pressed against the prepreg substrate 1. As a result, when the tip 28 of the blade completely penetrates the tape-like support 30, the handleability of the cut prepreg base material is lowered, and the tip of the cut portion does not reach the tape-like support. The fiber cannot be cut, continuous fibers remain in the cut prepreg base material, and the fluidity at the time of molding decreases. Therefore, the thickness of the tape-like support 30 is preferably 30 to 300 μm, and more preferably 50 to 200 μm.

  In the cutting insertion step of (1) or the cutting step of (2), a cooling mechanism for cooling the prepreg base material is provided, and before the reinforcing fiber is divided or before the prepreg base material is cut out. Alternatively, the prepreg base material may be cooled when the reinforcing fiber is divided or when the prepreg base material is cut out. In particular, in a prepreg base material using a thermosetting resin, when the temperature increases, the viscosity of the resin decreases, and the reinforcing fibers easily escape from the blade. By reducing the temperature of the prepreg, the resin viscosity can be kept high and cut errors can be prevented. As a method for cooling the prepreg substrate, for example, a method in which the prepreg substrate is brought into direct contact with a cooled metal plate called a chilled plate, or a method in which the prepreg substrate is brought into direct contact with a cooled roller is effective.

  As described above, in the cutting insertion process or the base material cutting process, it is preferable to use a punching blade in which a plurality of blades are attached to a flat base as a punching die. For example, it is preferable to embed the blade in a base metal plate, veneer plate or the like and attach it to a press as a die. If this method is used, it is easy to produce a punching die, and the amount of protrusion of the blade can be easily adjusted. Furthermore, since it is not necessary to cut the blade directly from the metal, a more durable blade can be used for the punching die, and the prepreg base material can be cut stably.

  Furthermore, in the cutting insertion process or the base material cutting process, it is preferable to use a rotary blade provided with a plurality of blades as a cutting die. Since the cutting can be inserted only by rotating the rotary blade while pressing the rotary blade against the base material in accordance with the feed rate of the base material, productivity is good and preferable.

  In the case of using a rotary blade, the roller may be directly cut out to provide a predetermined blade. The replacement of the blade is easy and preferable. By using such a rotary blade, it is possible to insert a cut well even with a cut prepreg base material having a small Ws (specifically, 1 mm or less). When fixing the sheet-shaped mold to the roller, it may be attached directly to the roller surface using an adhesive or the like. However, the mold is fixed to the roller by vacuum suction, or the mold is made of metal. If a method such as fixing with a magnetic force by a magnet or the like is used, the mold can be attached and detached, and the replacement work when the blade is deteriorated can be smoothly advanced.

  However, when using the plate-shaped blade to insert a cut as shown in FIG. 8A, for example, it becomes difficult to connect the cut pattern in the circumferential direction of the rotary blade at the joint of the blade. In that case, if a rotary blade is produced by winding a belt-like blade along the cutting direction as shown in FIG. 13A around a roller spirally as shown in FIG. The cutting pattern can be continued in the circumferential direction.

  As the use of the fiber reinforced plastic molded by the production method of the present invention, strength, rigidity and light weight are required, such as bicycle parts, shafts and heads of sports parts such as golf, automobile parts such as doors and seat frames, There are mechanical parts such as robot arms. In particular, the present invention can be preferably applied to automobile parts such as seat panels and seat frames that require molding followability of complicated shapes in addition to strength and light weight.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the inventions described in the examples.

<Preparation method of prepreg base material>
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.

The resin films obtained by the above procedure are overlapped on both sides of carbon fibers arranged in one direction (tensile strength 4,900 MPa, tensile modulus 235 GPa), respectively, and impregnated with resin by heating and pressurizing. A prepreg base material having a carbon fiber weight of 125 g / m ² , a fiber volume content Vf of 55%, and a thickness of 0.125 mm was produced.

<Method of forming convex fiber-reinforced plastic>
A convex fiber-reinforced plastic was molded using the mold shown in FIG. The laminated base material was placed in a void portion of a mold heated to 150 ° C., and molding was performed under conditions of a molding temperature of 150 ° C., a holding time of 30 minutes, and a molding pressure of 5 MPa.

  Moreover, the surface quality was evaluated as follows from the properties of the molded product of the obtained convex fiber-reinforced plastic. The base material is not filled up to the end and the R part appears yellowish and the resin rich part is observed x, and the former or the latter can be confirmed only △, both confirmed The ones that were not done were marked with ○.

<Flat plate forming method>
After the prepreg laminate was placed at the approximate center on a flat plate mold having a 250 × 250 mm cavity, it was cured by a heating type press molding machine under conditions of 150 ° C. × 30 minutes under a pressure of 5 MPa. . As a result, a flat fiber-reinforced plastic having a size of 250 × 250 mm was obtained.

<Mechanical property evaluation method>
By the above procedure, a tensile strength test piece having a length of 250 ± 1 mm and a width of 25 ± 0.2 mm was cut out from the obtained flat fiber reinforced plastic. According to the test method prescribed in JIS K-7073 (1998), the tensile strength was measured at a crosshead speed of 2.0 mm / min with a distance between the gauge points of 150 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.

( Comparative Example 1) [Cut angle 90 °, full cut]
A cut was inserted into the unidirectional prepreg substrate obtained by the above procedure to obtain a cut prepreg substrate. First, a number of blades were cut out from a metal plate having a size of 500 mm × 500 mm and a thickness of 5 mm, and a punching die for inserting a cut into a prepreg base material was produced. FIG. 14 shows the layout of the cutting blades. A plurality of blades 11 having a length W of 10 mm are arranged at an interval of 10 mm in the central portion of the punching die 10 and a region having a diameter of 300 mm, thereby forming a row 34 of blades. An angle α (36) formed by the row of blades and the reference direction 35 of the punching die is 90 °. Further, the rows of adjacent blades are arranged at a spacing 37 of 15 mm in the reference direction of the punching die, and the rows of adjacent blades are shifted from each other by a half phase in a direction 38 perpendicular to the reference direction. Furthermore, a circular blade having a diameter of 300 mm was cut out from a metal plate having a thickness of 500 mm × 500 mm and a thickness of 5 mm, and this was used as a punching die used in the cutting process.

Next, as shown in FIG. 2, the two punching dies are attached to a press machine, and the prepreg base material is placed so that the reference direction of the punching die and the feed direction of the base material (fiber longitudinal direction of the prepreg base material) coincide. While feeding, the die was pressed against the prepreg base material, and a cut was inserted into the prepreg base material. At this time, the cutting pattern of the obtained cutting prepreg base material was a pattern in which the blade layout of FIG. 14 was transferred as it was. The surface of the obtained cut prepreg base material is photographed using a digital microscope, printed out so that the magnification becomes 100 times, and the cut length W, the fiber length L, and the projection using a curve ruler. When the length Ws was measured, W = 10 mm, L = 30 mm, and Ws = 10 mm, respectively. Further, the center line of the cut is divided into 20 equal parts, the angle formed by each minute line segment and the fiber longitudinal direction is measured with a protractor, and the average value is defined as the absolute value Θ of the angle formed by the cut and the carbon fiber. , Θ was 90 °. The cut-out prepreg base material was laminated in 16-layer pseudo-isotropic ([−45 / 0 / + 45/90] _2S ) to obtain a disc-shaped prepreg laminate having a diameter of 300 mm.

  The laminate was molded into a convex fiber reinforced plastic by the above procedure. In the obtained fiber reinforced plastic, the opening of the cut portion was observed as shown in FIG. 9B, but there was no warp, and the base material was filled up to the end of the mold, maintaining a good surface quality. It was.

  Moreover, the edge part of the said laminated body was cut off and the rectangular prepreg laminated body of 200 mm x 200 mm was produced. Furthermore, according to the said procedure, the flat fiber reinforced plastic of 250 mm x 250 mm was shape | molded, and the tension test was implemented. As a result, the tensile strength is 380 MPa and the CV value is 4%, which is significantly higher than the SMC of Comparative Example 2 to be described later, with less variation, and can be sufficiently applied to the product. It could be confirmed.

( Comparative Example 2, Examples 3-6, Comparative Example 7 ) [Comparison of cutting angles (Table 1)]
Except that the angle of cut was changed, flat and convex fiber-reinforced plastics were obtained in the same manner as in Comparative Example 1. Comparative Example 2 has a cutting angle Θ of 1 °, Example 3 has a cutting angle Θ of 2 °, Example 4 has 5 °, Example 5 has 10 °, Example 6 has 25 °, and Comparative Example 7 Provided a continuous cut in the direction of 45 °.

None of the obtained flat fiber reinforced plastics had fiber undulations, and the fibers were flowing evenly to the ends. In addition, the smaller the cut angle, the smaller the opening of the cut portion. The same tendency was also observed in convex fiber reinforced plastics. The tensile modulus was 46 to 47 GPa, the tensile strength was as high as 350 to 680 MPa, and the CV value of the tensile strength was as small as 4 to 6%. It was confirmed that the mechanical strength was improved as the cutting angle became smaller. On the other hand, in Comparative Example 2, since the cutting angle was small, the cutting was inserted very densely, so that there was some difficulty in handling at the time of stacking.

(Examples 8 to 12) [Comparison of projection length Ws (Table 2)]
A flat plate-like and convex fiber-reinforced plastic were obtained in the same manner as in Example 5 except that the length of the cut was changed. The projected length Ws projected in the vertical direction of each cut fiber was 0.07 mm in Example 8, 0.17 mm in Example 9, 0.26 mm in Example 10, 1.5 mm in Example 11, and In Example 12, it was set to 2.0 mm. At this time, the actual cut lengths were 0.40 mm in Example 8, 1.0 mm in Example 9, 1.5 mm in Example 10, 8.6 mm in Example 11, and 11 in Example 12, respectively. 0.5 mm.

  The obtained fiber reinforced plastic had no fiber swell except in Example 8. On the other hand, in Example 8, it was also confirmed that if Ws was too small, the fibers meandered and many uncut parts were left, or the fluidity was slightly lowered. In addition, in all of the fiber reinforced plastics, the fibers sufficiently flowed to the end portions thereof, and there was no warp and good appearance quality was maintained. In particular, in Examples 8 to 11, even in the outermost layer cut portion, there is almost no portion where the reinforcing fibers are not present and the reinforcing fibers in the adjacent layer are not present, and the surface quality is very good. there were. Moreover, the tensile strength was a very high level of 590 MPa to 730 GPa. Further, it was confirmed that the smaller Ws is, the higher the strength is, and the tendency is particularly strong when Ws is 1.5 mm or less.

(Examples 13 to 15) [Fiber length comparison (Table 3)]
A flat and convex fiber reinforced plastic was obtained in the same manner as in Example 5 except that the fiber length was changed. The fiber length L was 10 mm in Example 13, 60 mm in Example 14, and 100 mm in Example 15.

  Each of the obtained convex fiber reinforced plastics was filled with the base material up to the end of the mold, and was of a good quality that was almost inferior to Example 5. However, it was considered that there was a portion that looked slightly yellow in the R portion of Example 15, and a resin rich portion was formed. It was confirmed that the longer the fiber length, the lower the fluidity.

  Regarding the tensile strength, the strength was very high at 520 MPa to 650 MPa. Moreover, it has confirmed that there exists a tendency for it to become high strength, so that fiber length becomes long.

(Example 16) [Half cut only for cutting insertion process]
A fiber reinforced plastic was obtained in the same manner as in Example 5 except that in the cutting insertion process, the tip of the blade did not penetrate the release paper. At this time, the depth at which the blade edge entered the release paper was half the depth of the release paper.

  Since the obtained cut-out prepreg base material was supported by release paper, the base material was not deformed during the laminating operation, and a prepreg laminate could be easily produced. This technology was considered to be a technology that led to a significant improvement in work efficiency.

  In addition, the obtained convex fiber reinforced plastic is filled with the base material up to the end of the mold, and no resin rich portion is observed in the R portion, which is comparable to Example 5. The quality was good.

(Example 17) [When cutting is only convex part]
A convex fiber-reinforced plastic was obtained by the same means as in Example 5, except that the area where the cutting blade used for the cutting insertion process was arranged was within a circle having a diameter of 150 mm. At this time, the cut-out prepreg base material was a circular prepreg base material having a diameter of 300 mm, and many cuts were inserted only in a circle having a diameter of 150 mm at the center.

The obtained convex fiber reinforced plastic is filled with the base material up to the end of the mold, and no resin-rich part is observed in the R part, which is excellent in quality compared with Example 5. Met. It was confirmed that high fluidity was obtained while suppressing the amount of cutting by making the amount of cutting only the bent portion. (In addition, reducing the amount of cutting is preferable from the standpoint of mechanical strength and processing costs.)
Example 18 [Thermoplastic Resin]
A fiber reinforced plastic was obtained in the same manner as in Example 5 except that the matrix resin used was a thermoplastic resin.

Pellets of copolymerized polyamide resin (“Amilan” (registered trademark) CM4000 manufactured by Toray Industries, Inc., polyamide 6/66/610 copolymer, melting point 155 ° C.) with a press machine heated at 200 ° C. to form a film having a thickness of 34 μm It was processed into. A cut prepreg base material was obtained in the same manner as in Example 5 except that the release paper was not used, and then 16 layers were stacked in a pseudo isotropic manner ([−45 / 0 / + 45/90] _2S ) and heated to 170 °. A press machine was intermittently pressurized several times under the condition of 1 MPa to obtain a prepreg laminate.

  Further, a convex fiber-reinforced plastic was molded using the same mold as in Example 5. The prepreg laminate is placed in a mold heated to 200 ° in advance, and is allowed to flow under a pressure of 6 MPa for 1 minute. After cooling without opening the mold, the mold is removed and the convex A shaped fiber reinforced plastic was obtained.

  The obtained convex fiber reinforced plastic was filled with the base material up to the end of the mold, and the resin rich part was not observed even in the R part. Compared with Example 5, the quality was inferior. Even when the matrix resin was a thermoplastic resin, it was confirmed that a molded article of good quality could be obtained.

(Embodiment 19) [The cutting die for cutting insertion / cutting process is the same]
A flat or convex fiber-reinforced plastic was obtained in the same manner as in Example 5 except that the same cutting die was used for the cutting insertion step and the cutting step.

  A blade similar to the blade used in the cutting insertion process is cut out from a metal plate having a size of 500 mm × 500 mm and a thickness of 5 mm, and then a circular blade having a diameter of 300 mm used in the cutting process is cut out. It was. The punching die was attached to the press machine for the cutting insertion process of Example 5, the press machine was operated (the pressing machine in the cutting process was stopped), and a cut prepreg base material was obtained.

  In the obtained convex fiber reinforced plastic, the base material is filled up to the end of the mold, and the resin rich portion is not observed even in the R portion, and the quality is inferior to that of Example 5. there were. Moreover, by performing the cutting insertion process and the cutting process at the same time, it was possible to greatly reduce the equipment cost, processing cost, etc. that were spent on the base material cutting.

(Example 20) [Rotating blade]
A flat or convex fiber-reinforced plastic was obtained in the same manner as in Example 19 except that the punching die used was a rotary blade.

  In the cutting pattern of Example 19, instead of cutting out the flat metal, the cylindrical metal was cut out to provide a plurality of blades on the circumference to form a rotary blade roller, and the rotary blade roller was used as a prepreg base material. A cut-out prepreg base material was obtained by pressing. The used metal roller is a cylindrical roller having an axial length of 40 cm and a diameter of 180 mm. A number of blades were cut out from this roller so as to have the same cutting pattern as in Example 19, and a rotary blade roller was produced. The rotary blade roller and the rubber roller paired with the rotary blade roller were arranged so that the axes of the rollers were parallel and in contact with each other. Furthermore, the cutting insertion process and the cutting process were implemented by sending a base material between both rollers, rotating both rollers.

  The obtained convex fiber reinforced plastic is filled with the base material up to the end of the mold, and the resin rich portion is not observed even in the R portion, and is excellent in quality compared with Example 19. Met.

  Hereinafter, a comparative example is shown.

(Comparative Example 1) [Comparison with a continuous fiber prepreg base material]
It was the same as Comparative Example 1 except that the prepreg base material was not cut.

  The obtained convex fiber reinforced plastic was not filled with the base material up to the end of the mold, and had a resin pool. Further, in the vicinity of the central R portion, the prepreg laminate was strongly pressed against the mold, so that the resin was squeezed out and the resin surface was scratched, so it seemed that it could not be applied to the product.

(Comparative Example 2) [Comparison with SMC]
Except that the unidirectional prepreg base material of Comparative Example 1 was cut into a fiber length of 30 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. Obtained the prepreg base material and the laminated body like the comparative example 1, and shape | molded the flat fiber reinforced plastic.

In the obtained flat fiber reinforced plastic, the carbon fibers were wavy and the carbon fibers were evenly and sufficiently flowed to the end of the mold, but the flow state was not uniform, so warpage was caused by the difference in linear expansion coefficient. . Moreover, since the tensile strength was 210 MPa, which was significantly lower than that of Comparative Example 1 and the flow state was not uniform, the CV value was as high as 12%, and the variation was large.

(Comparative example 3) [When cutting insertion process and cutting process are different]
After the cutting insertion process is completed, the cut prepreg base material is once wound into a roll, and the cutting prepreg base material is pulled out again to perform the cutting process. A reinforced plastic was obtained.

By reapplying the prepreg base material, the mutual position of the cutting die position and the notch in the cut prepreg base material was shifted by about 4 mm at the maximum. This method is considered inappropriate from the viewpoint of quality assurance as well as the cost increase due to the increased number of processes.

(Comparative Examples 4 and 5) [Comparison of fiber length]
In the cutting pattern of Example 5, flat and convex fiber reinforced plastics were obtained in the same manner as in Example 5 except that the fiber length L was changed by changing the cutting interval. L was 7.5 mm in Comparative Example 4 and 120 mm in Comparative Example 5, respectively.

  In Comparative Example 4, since the fiber length was short, the amount of cuts inserted into the base material was large, and there was a considerable difficulty in the laminating operation. Further, the tensile strength was 450 MPa, which is lower than that of Example 5, and the CV value was 9%, which was a large variation.

  In the comparative example 5, it has confirmed that the resin rich part was formed in the edge part of a convex fiber reinforced plastic. Since the fiber length was too long, sufficient fluidity could not be obtained, and it was considered that the fiber did not fill up to the end of the mold.

It is the schematic which shows the flow of the manufacturing method of this invention. It is a perspective view which shows an example of the cutting insertion process in this invention, and a cutting process. It is a perspective view which shows an example of the cutting insertion process in this invention, and a cutting process. It is a perspective view which shows an example of the cutting insertion process in this invention, and a cutting process. It is a top view which shows an example of the cutting pattern of this invention. It is a plane enlarged view which shows an example of the cutting pattern of this invention. It is a top view which shows an example of the cutting pattern for a comparison. It is a top view which shows an example of the cutting pattern of this invention. It is the top view and sectional drawing which show an example of the prepreg laminated body for a comparison, and a fiber reinforced plastic. It is the top view which shows an example of the prepreg laminated body which concerns on this invention, and a fiber reinforced plastic, and sectional drawing. It is a top view which shows an example of the prepreg laminated body which concerns on this invention, and a fiber reinforced plastic. It is sectional drawing which shows an example of the cutting insertion process in this invention, and a cutting process. It is the top view and perspective view which show an example of the cutting die used for this invention. It is a top view which shows an example of the cutting die used for this invention. It is the top view and perspective view which show an example of the shaping | molding method in this invention. (A) is a perspective view and a sectional view showing an example of a comparative molding method and fiber reinforced plastic, and (b) is a perspective view and a cross section showing an example of the molding method and fiber reinforced plastic of the present invention. FIG.

Explanation of symbols

1: prepreg base material 2: notch 3: notched prepreg base material 4: short fiber group 5: cut prepreg base material 6: prepreg laminate 7: molding die 8: bent portion 9: fiber reinforced plastic 10: punching die 11 : Blade 12: Base 13: Fiber orientation direction 14: Fiber orthogonal direction 15: Rotary blade 16: Reinforcing fiber 17: Angle Θ formed by cutting and fiber orientation direction
18: Length Ws obtained by projecting the cut in the vertical direction of the reinforcing fiber
19: Width at which fibers are divided 20: Fiber length 21: Short fiber layer 22: Region where no reinforcing fiber exists (cut opening)
23: Adjacent layer 24: Fiber bundle end 25: Resin rich portion 26: Layer waviness 27: Reinforcement fiber rotation 28: Cutting edge 29: Film 30: Tape-shaped support 31: Plate-shaped mold 32: Mold end 33: Roller 34: Row of blades 35: Die reference direction 36: Angle α
37: Spacing between rows of blades 38: Direction perpendicular to the reference direction of the punching die 39: Molding die (upper die)
40: Mold (lower mold)
41: Substrate unfilled part

Claims (12)

A method for producing a fiber reinforced plastic by pressing a laminate of a prepreg base material composed of reinforced fibers and a matrix resin aligned in one direction to obtain a fiber reinforced plastic having a three-dimensional curved surface. A method for producing a fiber reinforced plastic, wherein the fiber reinforced plastic is molded through the steps (1) to (4).
(1) A plurality of intermittent or continuous cuts are inserted into a prepreg base material by pressing a die having a blade disposed thereon, and at least some of the reinforcing fibers are cut into a length of 10 to 100 mm and short. Incision insertion step for forming a fiber group, where the angle between the incision and the reinforcing fiber is Θ, the absolute value of Θ is in the range of 2 to 25 ° ( incision insertion step ( 2) At the same time as or in succession to the notch insertion step of (1), a prepreg base material including the short fiber group is cut into a predetermined shape, and a cutout step is made into a cut prepreg base material. (3) The cut prepreg base material is Lamination step (4) to obtain a prepreg laminate by stacking a plurality of sheets, placing the laminate on a mold, pressing the laminate against the mold and curing or solidifying the fiber-reinforced plastic, Before at least part of the bending part of the mold The short fiber group Ategai, molding step be along the bent portion of the mold The resin is a thermosetting resin or a thermoplastic resin, and in the molding step (4), the molding die is heated to a temperature higher than that of the laminate, and the laminate is pressed against the molding die to be cured or The manufacturing method of the fiber reinforced plastics of Claim 1 solidified. In the molding step (4), the resin is a thermoplastic resin, and after heating the laminated body, the molding die is cooled to a temperature lower than the laminated body, and the laminated body is pressed against the molding die. The method for producing a fiber-reinforced plastic according to claim 1, wherein the fiber-reinforced plastic is solidified. In the cutting insertion process of (1) and the cutting process of (2), the same cutting die is used to simultaneously cut the reinforcing fibers and cut the prepreg base material. The manufacturing method of the fiber reinforced plastic as described in 2 .. In virtually all cuts, the projected length Ws projected in the vertical direction of the reinforcing fiber the cut is intermittent cuts in the range of 0.1 mm to 1.5 mm, according to claim 1-4 The manufacturing method of the fiber reinforced plastic in any one of. Wherein the entire surface cutting the insertion of cut prepreg base, the fiber length of substantially all of the reinforcing fibers contained in the cut prepreg base is in the range of 10 to 100 mm, more of claims 1-4 A method for producing the fiber-reinforced plastic according to claim 1. In the cutting insertion step of (1) or the cutting step of (2), the prepreg base is removed from the opposite side of the tape-shaped support using the prepreg base material gripped by the tape-shaped support. pressed against the wood, penetrate the prepreg base material, and said cutting die inserts the cut so as to penetrate only part of the tape-shaped support, according to any one of claims 1 to 6 Manufacturing method for fiber reinforced plastic. In the cutting insertion step of (1) or the cutting step of (2), a cooling mechanism for cooling the prepreg base material is provided, and before the reinforcing fiber is divided or before the prepreg base material is cut out. or, when crop cutting time or the prepreg base material of the reinforcing fibers, cooling the prepreg base material, method for producing a fiber reinforced plastic according to any one of claims 1-7. The fiber according to any one of claims 1 to 8 , wherein a rotary blade having a plurality of blades provided on a roller is used as a cutting die in the cutting insertion step of (1) or the cutting step of (2). A method of manufacturing reinforced plastics. The method for producing a fiber-reinforced plastic according to claim 9 , wherein the rotary blade has a plate-like blade attached to a roller surface in a cylindrical shape and is removable. The manufacturing method of the fiber reinforced plastics of Claim 10 with which the said plate-shaped blade is wound around the roller surface spirally in the said rotary blade. Cutting insert step (1) or in cutout step (2), is used as a cutting die tabular punching blade having a plurality of blades attached to the base of any of claims 1-8 The manufacturing method of the fiber reinforced plastic as described in 2 ..

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