JP2008273176A - Manufacturing method for fiber-reinforced plastic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a core-shell type fiber-reinforced plastic that is manufactured by using a plastic prepreg having good fluidity and shaping followability to a complex shape, and exhibits excellence in a physical property, its small variation and dimensional stability. <P>SOLUTION: The manufacturing method of the core-shell type fiber-reinforced plastic comprises the shaping process (1) of mounting a laminate of a plurality of prepreg base materials containing a cut prepreg base material, the molding process (2) of arranging the laminate in a shaping mold, softening a thermosetting resin, injecting a foaming resin, foaming the same, curing the same, at the same time extending the laminate under foaming pressure of the foaming resin and pushing the same to the shaping mold to cure and form the core-shell type fiber-reinforced plastic, and the mold-removing process (3) of taking out the fiber-reinforced plastic from the shaping mold, these processes being conducted in this order. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention has a good fluidity and molding followability, and when a fiber reinforced plastic is used, a closed-shaped sheath portion that exhibits excellent mechanical properties, low variation, and excellent dimensional stability; The present invention relates to a method for manufacturing a fiber-reinforced plastic having a core-sheath structure constituted by a core portion formed of a foam material provided inside a closed shape. 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 plastics composed of reinforced fibers and thermosetting resins are attracting attention in industrial applications due to their high specific strength, specific elastic modulus, excellent mechanical properties, and high functional properties such as weather resistance and chemical resistance. The demand is increasing year by year.

  In order to realize high mechanical properties of fiber reinforced plastics in a lighter weight, a core / sheath structure composed of a core part made of foam material and a sheath part made of fiber reinforced plastic is often adopted. Although a sheath part may be arranged only on the upper and lower surfaces of the core part, in particular, by arranging the sheath part continuously around the core part (for example, a cylindrical shape or a hook-shaped sheath part covers the core part). It can cope with external loads from various unexpected directions and is suitable for structural members.

  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 and 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, on the other hand, there is a problem that it is difficult to form a complicated shape such as a three-dimensional shape because it is a continuous fiber.

  In particular, this problem is more serious in the case of the core-sheath structure constituted by the closed-shaped sheath part made of fiber-reinforced plastic and the core part made of the foam material provided inside the closed shape. A foam material cut into a predetermined shape or a foam material obtained by injecting and foaming into a predetermined shape is used as a core, and a sheet base material made of reinforcing fibers and a thermosetting resin is laminated on the core. However, it is conceivable to form the sheath portion by molding, but in addition to the cost itself of adding a process for giving a preliminary shape to the foam material, such as cutting or injection foaming, the sheet base Forming the material further along the shape is very laborious and expensive.

In order to form a fiber-reinforced plastic having a core-sheath structure as described above, for example, a pultrusion method as disclosed in Patent Document 1 is disclosed. A fiber reinforced plastic with a core-sheath structure that forms a foam material by foaming and curing the foamable resin while placing a reinforced fiber base around the foamable resin and drawing it into the mold. Can be obtained continuously. However, since the fiber base material is stretched without extending in the fiber direction, there is a problem that the fiber base material does not adhere to the mold depending on the location and the appearance quality is deteriorated or the shape cannot be followed to a complicated shape.
Japanese Patent Laid-Open No. 9-169057

  In view of the background of such prior art, the present invention has excellent fluidity, molding followability of complicated shapes, and excellent mechanical properties, low variability, and excellent dimensional stability when used as a fiber reinforced plastic. Is to provide a fiber-reinforced plastic having a core-sheath structure and a method for producing the same.

The present invention employs the following means in order to solve such problems. That is,
(I) Using a prepreg base material composed of reinforcing fibers aligned in one direction and a thermosetting resin, a closed sheath portion and a foam material provided inside the closed shape A method of manufacturing a fiber-reinforced plastic having a core-sheath structure constituted by a core portion, wherein the prepreg base material has at least a part of reinforcing fibers having a length of 10 to 100 mm by a plurality of cuts in a direction crossing the reinforcing fibers. A method for producing a fiber-reinforced plastic, wherein a fiber-reinforced plastic is molded through at least the following steps (1) to (3) in sequence using the cut prepreg base material.
(1) A laminate in which a plurality of prepreg base materials including the cut prepreg base material are laminated is provided on a substantially shaped mandrel of the final shape of the fiber reinforced plastic, and is shaped smaller than the final shape of the fiber reinforced plastic. After that, the shaping step for decentering the mandrel (2) The laminated body is placed in a molding die which is an outer mold, and the thermosetting resin of the laminated body is softened by heating to decenter the mandrel. Foamed resin is injected into the location, foamed and cured to form a foam material, and at the same time the core is formed, the laminate is stretched with the foaming pressure of the foamable resin, pressed against a mold and cured, Forming the sheath from the laminate, integrating the sheath and the core, and molding the fiber-reinforced plastic having the core-sheath structure (3) Demolding step of taking out the fiber-reinforced plastic from the mold (II) Small The fiber according to (I), wherein a region where only the cut prepreg base material in which the reinforcing fibers are cut into a length of 10 to 100 mm is laminated is formed in a part of the laminate. A method of manufacturing reinforced plastics.

  (III) All of the reinforcing fibers constituting the cut prepreg base material are cut by the cut, and the fiber length L cut by the cut is in the range of 10 to 100 mm, (I) or The manufacturing method of the fiber reinforced plastic as described in (II).

  (IV) The incision of the notched prepreg base material is linear, and the projection length Ws obtained by projecting the incision in the vertical direction of the reinforcing fiber is 30 μm to 100 mm, and is disposed intermittently and periodically over the entire surface. A method for producing a fiber-reinforced plastic according to any one of (I) to (III).

  (V) The notch prepreg base material is continuously adjacent to two or more layers, and an arbitrary notch geometric center on one notch prepreg base material for any two adjacent layers among the two or more layers. And the other cut prepreg substrate, the fiber-reinforced plastic production method according to any one of (I) to (IV), wherein the layers are laminated so as to be separated from the geometric center of any cut by 5 mm or more.

  (VI) The method for producing a fiber-reinforced plastic according to any one of (I) to (V), wherein the notch is inclined from a direction perpendicular to the fiber.

  (VII) The method for producing a fiber-reinforced plastic according to any one of (I) to (V), wherein an absolute value of an angle Θ formed by the cut with the reinforcing fiber is in the range of 2 to 25 °.

  (VIII) The method for producing a fiber-reinforced plastic according to any one of (I) to (VII), wherein the laminate is composed only of the cut prepreg base material.

  (IX) The fiber reinforcement according to any one of (I) to (VIII), wherein the laminate used in the shaping step of (1) is formed by sequentially shaping the prepreg base material on the mandrel. Plastic manufacturing method.

  (X) After forming the laminated body used at the shaping process of said (1) by laminating | stacking the said prepreg base material in flat form, the said laminated body is shaped on the said mandrel, (I)-( The manufacturing method of the fiber reinforced plastic in any one of VIII).

  (XI) While taking up the laminate, the steps (1) to (3) are continuously performed to obtain a fiber-reinforced plastic having a cylindrical core-sheath structure. The manufacturing method of the fiber reinforced plastic of description.

  (XII) In the molding step (2), a fiber-reinforced plastic having a cylindrical core-sheath structure with a deformed cross section is obtained by pressing against a mold that continuously changes into a different shape. Method.

  According to the present invention, the closed shape has good fluidity, molding conformability of complex shapes, and exhibits excellent mechanical properties, its low variability, and excellent dimensional stability when used as a fiber reinforced plastic. A fiber-reinforced plastic having a core-sheath structure constituted by a sheath part of the core and a core part made of a foam material provided inside the closed shape can be obtained.

  The present inventors have good fluidity, molding conformability of complex shapes, and when made into fiber reinforced plastic, it exhibits excellent mechanical properties, its low variation, excellent dimensional stability, closed shape Carbon fiber that has been intensively studied and produced in one direction, with regard to a method for producing a fiber-reinforced plastic having a core-sheath structure composed of a sheath portion of the core and a core portion made of a foam material provided inside the closed shape And a prepreg base material composed of a thermosetting resin and a notched prepreg base material in which a specific notch pattern is inserted into a specific base material, and the laminated prepreg base material is laminated on a mandrel. After placing in the mold to determine the outer shape, inject foamable resin into the location where the mandrel is decentered, foam and cure to form foam material, and at the same time expand the laminate with foaming resin foam pressure The Is extended to lamina cured against the mold, by molding a fiber-reinforced plastic sheath structure integrated with the foam material is to that investigation to solve such problems at a stroke.

  In the present invention, the “closed shape” means a shape having a substantially internal space, such as a bowl shape or a cylindrical shape. There is no particular limitation on the shape of the internal space, for example, there may be ribs or bosses inside, and it may be divided into several spaces by partitions, etc., and an opening that connects the internal space and the external space May be provided. In the present specification, unless otherwise specified, in the term including fibers or fibers (for example, “fiber direction” and the like), the fibers represent reinforcing fibers. In addition, the prepreg base material used in the present invention has a resin sheet completely impregnated between the fibers, in addition to the reinforcing fibers aligned in one direction and the base material in which the reinforcing fiber base material is completely impregnated with the resin. It includes a semi-impregnated resin base material (semi-preg: hereinafter also referred to as a semi-impregnated prepreg) integrated in a non-existing state. Further, the core-sheath structure defined in the present invention means a double structure in which the inner core part is surrounded by the surface sheath part, but when the outer shape is cylindrical, the foam material filling the inner space is In the case of a structure surrounded by a surface layer having two or more openings for accessing the internal space, the core-sheath structure referred to in the present invention is used, and when the outer shape is a bowl shape, the foam material filling the internal space is the internal space. If it is the structure surrounded by the surface layer which is one location, the core-sheath structure said by this invention is used, the said foam material is made into a core part and the said surface layer is made into a sheath part. The ribs, bosses, and partitions may be in the core portion or in the sheath portion.

  The cut prepreg base material used in the present invention is composed of a reinforcing fiber and a thermosetting resin aligned in one direction, and at least a part of the reinforcing fibers is cut by a plurality of cuts in a direction crossing the reinforcing fiber. It refers to what is divided into a length of ~ 100 mm. The area | region where the reinforcing fiber is divided | segmented into the length of 10-100 mm on the cutting prepreg base material respond | corresponds to the area | region which can be extended | stretched at the time of shaping | molding. Therefore, when molding a fiber reinforced plastic having a complicated shape, the laminated body in the region corresponding to the concavo-convex portion is laminated with a region in which the reinforcing fibers are divided into lengths of 10 to 100 mm by cutting in the cut prepreg base material. It is preferable that

  Since the reinforced fibers are aligned in one direction in the cut prepreg base material used in the present invention, it is possible to design a molded body having arbitrary mechanical properties by controlling the orientation in the fiber direction. In addition, by dividing at least a part of the fibers into a length of 100 mm or less by a plurality of cuts in the direction crossing the fibers, the fibers can flow at the time of molding, particularly in the longitudinal direction of the fibers. Excellent shape conformability. When there is no notch, that is, when only continuous fibers are used, a complicated shape cannot be formed because they do not flow in the fiber longitudinal direction. On the other hand, when the fiber length is less than 10 mm, the fluidity is further improved. However, even if other requirements are satisfied, the high mechanical properties necessary for the structural material cannot be obtained. Considering the relationship between fluidity and mechanical properties, the fiber length needs to be 10 to 100 mm, and more preferably within the range of 20 to 60 mm.

  FIG. 5 shows an example of the flow mechanism of the cut prepreg base material. As shown in FIG. 5 a), when molding is performed by applying pressure 13 from above the laminate 12 in which the 90 ° prepreg base material is sandwiched between the 90 ° prepreg base material, as shown in FIG. The resin forms a flow 14 in the direction of 90 °, and the opening 15 of the end of the reinforcing fiber occurs according to the flow. That is, the longitudinal direction of the fiber is not provided until the prepreg base material made of fibers aligned in one direction is cut, and the cut prepreg base material in which at least some reinforcing fibers are 10 to 100 mm in length is laminated. It is possible to flow into a complex shape, resulting in molding conformability of complex shapes.

  Thus, since the flow of the resin is the driving source, the flow of the fiber is preferably an appropriate Vf (fiber volume content). That is, Vf is preferably 65% or less because sufficient fluidity can be obtained. Moreover, although fluidity | liquidity improves, so that Vf is low, when Vf is less than 45%, since there exists a possibility that a high mechanical characteristic required for a structural material may not be acquired, it is preferable that Vf is 45% or more. Considering the relationship between fluidity and mechanical properties, it is more preferably in the range of 55-60%.

In the present invention, a fiber-reinforced plastic having a core-sheath structure composed of a closed sheath portion and a core portion made of a foam material provided inside the closed shape is molded using the above-described cut prepreg base material. In doing so, it is necessary to sequentially perform at least the following steps (1) to (3).
(1) A laminate in which a plurality of prepreg base materials including a cut prepreg base material are laminated is provided on a mandrel having a substantially shape of the final shape of the fiber reinforced plastic, and is shaped smaller than the final shape of the fiber reinforced plastic. After that, the shaping step for decentering the mandrel (2) The laminated body is placed in a molding die as an outer mold and heated to soften the thermosetting resin of the laminated body, and the mandrel is defoamed at the location where it is decentered. The resin is injected, foamed and cured to form a foam, and the core is formed.At the same time, the laminate is stretched by the foaming pressure of the foamable resin and pressed against the mold to be cured, and the sheath is formed from the laminate. (1) Molding step for molding the fiber-reinforced plastic having a core-sheath structure by integrating the sheath and the core, and (3) a demolding step of taking out the fiber-reinforced plastic from the mold.

  For example, in manufacturing a fiber-reinforced plastic having a core-sheath structure composed of a closed-shell-shaped sheath portion and a foam material provided inside the sheath portion, first, a fiber-reinforced plastic 16 having a final shape (FIG. 1c). A mandrel smaller than () is prepared, and a laminate in which a plurality of prepreg base materials including the cut prepreg base material are laminated on the mandrel is provided. That is, it is essential that the mandrel has the approximate shape of the finally obtained fiber-reinforced plastic. The approximate shape referred to here is a shape obtained by simplifying the shape of the obtained fiber reinforced plastic, and indicates a shape in which the number of irregularities is reduced or undulation is reduced. One of the most simplified forms is a cylindrical shape. Further, in the present invention, the wire-like framework, guide, and the like also form the approximate shape of the fiber reinforced plastic, and what can form the laminate into the approximate shape of the fiber reinforced plastic is called a mandrel. . In addition, when the molding method of the present invention is used, the accuracy of the laminate itself often does not affect the final molding quality. Therefore, when forming a simple cylindrical laminate, the laminate is manually shaped. In the present invention, this action is referred to as “providing on the mandrel and removing the mandrel”.

  Generally, a prepreg base material is difficult to follow a complicated shape during shaping. Therefore, there is a great merit that a fiber reinforced plastic having a complicated shape can be obtained by using a laminate that is simply wound into a simple shape, ultimately a cylindrical shape. That is, since the area | region which cut | disconnected the reinforcement fiber of the cut prepreg base material used for this invention in the length of 10-100 mm can be extended | stretched at the time of shaping | molding, it is not shaped according to the shape of fiber reinforced plastic. Can be molded. In addition, since the conventional laminate is bulky compared to the fiber reinforced plastic after molding, it is difficult to arrange the laminate in a mold that determines the outer shape of the fiber reinforced plastic after molding. If the laminate is placed in the mold, the laminate that does not fit in the mold will protrude, causing burrs and fiber biting in the gaps between the molds, and reducing the surface quality due to resin-rich parts and fiber disturbances. It was a cause. On the other hand, in the case of the present invention, since it is essential that the laminate is shaped smaller than the final shape, it is easy to carry into the mold and mold clamping, and problems such as the occurrence of burrs are solved at once. .

  The mandrel used in the present invention may be a hard metal or a soft solid such as silicon rubber, or a bag-like body such as silicon rubber, PP, PE, PET, or the like packed with compressed air or beads. It is also possible to have a shape that cannot be removed by a hard mandrel (for example, a bent pipe shape).

  In the method for producing a fiber reinforced plastic according to the present invention, after providing a laminate on a mandrel, the mandrel is decentered, the laminate is placed in a molding die that is an outer mold, and heated to heat cure the laminate. The foamable resin is softened and injected into the inside of the laminate, where the mandrel is decentered, and foamed and cured to form a foam material. At the same time, the core of the core-sheath structure is formed. A region in which the fibers of the laminate are divided into 10 to 100 mm in length by foaming pressure is stretched and pressed against a mold to be cured to form a sheath portion of a core-sheath structure from the laminate, and the sheath portion and the core The parts are integrated into a fiber-reinforced plastic with a core-sheath structure. Since the laminate is smaller than the final shape of the fiber reinforced plastic, it can be easily placed in a mold. Further, even when the stack inlet is small, the mold opening may be omitted at the time of molding, and the stack may be folded. The mold used in the present invention is divided into three or more molds corresponding to complex shapes, even if the fiber reinforced plastic can be extracted after molding, whether it is a single mold or a double-sided mold such as an upper mold and a lower mold. It may be a mold. The foamable resin may be injected under pressure of about 0.1 MPa to 3 MPa, or may be injected dropwise by its own weight and foamed by a chemical reaction. The example of FIG. 1b) shows a state in which foaming resin 27 is injected and pressed against a mold while the laminate 12 is stretched.

  After the sheath portion and the core portion have been cured, or after being cured to such an extent that they can be removed, the fiber reinforced plastic is taken out from the mold. After taking out the fiber reinforced plastic, it may be put in another oven and post-cured.

  Thus, according to the present invention, it is possible to easily manufacture a fiber-reinforced plastic having a core-sheath structure having high mechanical properties. The present invention is characterized in that it can be manufactured even if the shape of the fiber reinforced plastic is a complicated shape.

  More preferably, as shown in FIG. 4, at least a part of the laminated body has a region 37 in which only the cut prepreg base material in which the fibers are cut into lengths of 10 to 100 mm by cutting is laminated. good. That is, in the region 37, only the cut prepreg base material, which is substantially made only of fibers of 10 to 100 mm, is laminated in the thickness direction of the laminated body. Here, “consisting essentially of fibers of 10 to 100 mm” means that 95% or more of the number of reinforcing fibers contained in the region is divided into 10 to 100 mm. Hereinafter, this region is referred to as a discontinuous portion of the laminate.

  When molding a fiber reinforced plastic having a complex shape, the region of the laminate corresponding to the complex shape is a discontinuous portion, so that it can be easily stretched at the time of molding, and can follow a complex system. 4A) and 4B show examples in which a discontinuous portion is provided in a part of each laminate, and the upper drawing shows a plan view and the lower drawing shows a cross-sectional view taken along the line AA. FIG. 4a) shows an example in which five layers of cut prepreg base material 10a cut into the entire surface are laminated and a prepreg base material 11 made of continuous fibers smaller than the cut prepreg base material 10a is laminated on the surface of one layer. Show. The area | region 37 which is not covered with the prepreg base material 11 which consists of continuous fibers corresponds to a discontinuous part. In addition, as a prepreg base material which consists of continuous fibers, the prepreg base material which aligned the continuous fiber in one direction, the prepreg base material of a textile fabric, etc. can be considered. FIG. 4b) is a laminate 12 in which five layers of cut prepreg base material 10b, in which a part of the cut is made, are laminated, and all of the laminated cut prepreg base materials 10b are at the left end as shown in the upper view of FIG. 4b). An example in which a cut is made only in the area is shown. A region 37 in which the regions where the cuts of the respective cut prepreg base materials 10b are cut overlap each other corresponds to the discontinuous portion.

  The fiber reinforced plastic obtained in this way has a characteristic that the fiber length Lc of all the reinforced fibers included in at least a partial region of the fiber reinforced plastic is in the range of 10 to 100 mm.

  More preferably, all of the reinforcing fibers constituting the cut prepreg base material are cut by the cut, and the fiber length L cut by the cut is in the range of 10 to 100 mm. By making all the fiber lengths L of the cut prepreg base material 100 mm or less, it is possible to manufacture a cut prepreg base material and a laminate without considering the shape of the fiber reinforced plastic to be finally produced. Because it can, there is a big merit in terms of design and work efficiency. In addition, air trapped at the time of lamination is easily degassed by cutting in the thickness direction, voids are not easily generated, and high mechanical properties can be expected. In the present invention, “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 base material is divided into 10 to 100 mm.

  As one of the preferred incision forms of the incision prepreg base material, the incision is linear, and the projected length Ws in which the incision is projected in the vertical direction of the reinforcing fiber is 30 μm to 100 mm, and is intermittent and periodic And a cut prepreg substrate disposed over the entire surface. Since the cuts are not continuous but intermittent, the cut prepreg base material does not become loose due to the cuts, and is excellent in handleability during lamination. In addition, when the cuts are periodically arranged, the position of the cut can be controlled, and the physical properties can be controlled. Here, the “projection length Ws obtained by projecting the notch in the vertical direction of the reinforcing fiber” is as shown in FIG. 2, from the notch 4 using the notch 4 as the projection plane in the vertical direction (fiber orthogonal direction 2) of the reinforcing fiber 3. The length 9 when projected perpendicularly to the projection plane (fiber longitudinal direction 1) is indicated. In addition, the expression “arranged over the entire surface” means that the incisions that divide all the reinforcing fibers contained in the entire surface of the incised prepreg base material into a length of 10 to 100 mm are provided.

  The fiber bundle end portion generated by the cutting is likely to become a starting point of fracture due to stress concentration when a load is applied to the fiber reinforced plastic. Therefore, a smaller notch is advantageous in strength. Ws is an index indicating the amount of reinforcing fiber to be divided, and when Ws is 100 mm or less, the strength is greatly improved. However, when Ws is smaller than 30 μm, it may be difficult to control the cutting, and it may be difficult to ensure that L is 10 to 100 mm over the entire discontinuous portion of the reinforcing fiber. That is, if fibers that are not cut by cutting are present in a discontinuous portion that is expected to follow a complicated shape, the fiber may be remarkably lowered in fluidity. There is a problem that the area below 10 mm is increased and the strength may be lower than the design value. Conversely, when Ws is greater than 100 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. More preferably, the strength is significantly improved when Ws is 1.5 mm or less. That is, Ws is preferably 1 to 100 mm from the viewpoint that a cut can be inserted with a simple device. On the other hand, in view of the relationship between the ease of cutting control and mechanical properties, Ws is 30 μm. It is preferable that it is -1.5mm, More preferably, it exists in the range of 50 micrometers-1 mm.

  Hereinafter, an example of a preferable cutting pattern will be described with reference to FIG.

  A plurality of controlledly aligned cuts 4 are made on a prepreg base material in which reinforcing fibers are aligned in one direction. The fibers are divided by the pair of cuts in the fiber longitudinal direction 1 and the fiber length L of the reinforcing fibers on the prepreg substrate is substantially 10 to 100 mm by setting the interval 6 to 10 to 100 mm. Can do.

  FIG. 2 shows an example in which both the fiber length L and the projected length Ws obtained by projecting the cut in the vertical direction of the reinforcing fiber are one kind. The row 7a consisting of the first intermittent cuts and the row 7c consisting of the third intermittent cuts can be overlapped by moving L in the fiber longitudinal direction 1 and the second intermittent cuts. The row 7b made of the above and the row 7d made of the fourth intermittent cut can be overlapped by moving in the fiber longitudinal direction 1 in the L direction. Further, there are fibers cut into the first and second cut rows and the third and fourth cut rows, and the presence of the width 5 cut to the fiber length L or less ensures stable In particular, a cut prepreg base material can be produced with a fiber length of 100 mm or less. Several examples of the cut pattern are illustrated in FIGS. 3A to 3F, but any pattern may be used as long as the above conditions are satisfied. In FIG. 3, the arrangement of the reinforcing fibers is not shown, but the arrangement direction of the reinforcing fibers is the vertical direction in FIG. 3 a), b) or c) is a mode in which the cut is in the fiber orthogonal direction 2, and d), e) or f) in FIG. 3 is a mode in which the cut is inclined from the fiber orthogonal direction 2. Show. Among the fibers that are divided into cuts other than the pair of cuts, there are also fibers that are shorter than the fiber length, but such fibers are not included in the fibers having the fiber length L defined in the present invention. And the fewer the fibers of 10 mm or less, the better.

  As described with reference to FIG. 5, the cut prepreg base material used in the present invention is a prepreg base material in which the fibers are aligned in one direction because the resin flow in the 90 ° direction is the driving force of the fiber flow. When two or more layers are laminated in different fiber directions, fluidity in the fiber longitudinal direction is expressed. Therefore, the layer adjacent to the cut prepreg base material is a prepreg base material (including the cut prepreg base material according to the present invention) in which reinforcing fibers are oriented in one direction, and is laminated in a fiber direction different from the cut prepreg base material. It is good to be. When it is unavoidable to stack the cut prepreg base materials in the same fiber direction adjacent to each other, it is preferable to stack the cuts so that the cuts do not overlap. Moreover, a resin film etc. may be laminated | stacked between the layers of these cutting prepreg base materials, and fluidity | liquidity may be improved. In addition, a continuous fiber base material can be disposed in a region that does not need to flow, and the mechanical properties of the region can be further improved. Depending on the shape, the unidirectional prepreg base material having no cut and the cut prepreg base material according to the present invention may be laminated and used. For example, in the case of a cylindrical body having a uniform cross-sectional shape as shown in FIG. 8b), there is no problem in fluidity even if continuous fibers are arranged in a direction where there is no change in shape.

  If the fiber direction is different between layers, a difference occurs in the flow direction and distance of each layer, but the displacement difference can be absorbed by sliding between the layers. That is, even if the fiber volume content Vf is as high as 45 to 65%, the laminate used in the present invention can exhibit high fluidity because the resin can be unevenly distributed between the layers. In the case of SMC (Sheet Molding Compound), fluidity is different between randomly chopped strands and they try to flow in different directions, but the fibers interfere with each other and do not flow easily, and the maximum Vf is about 40%. Only liquidity can be secured. That is, the laminate used in the present invention has a characteristic that high fluidity can be expressed even with a high Vf configuration capable of improving mechanical properties. In addition, due to the characteristics of this fluidity, the obtained fiber reinforced plastic can maintain a laminated structure even if it has a complex shape, expresses high elastic modulus and strength, reduces strength variation, and also has impact characteristics. Greatly improved. In addition, in a hybrid laminate of a continuous fiber base material such as a textile base material and a cut prepreg base material, the layer between the continuous fiber base material and the cut prepreg base material slides even if the cut prepreg base material follows a complex shape. Thus, the continuous fiber substrate can follow a certain shape without difficulty.

  More preferably, the notch prepreg base material is adjacent to two or more layers in succession, and for any two adjacent layers of the two or more layers, the geometric center of any incision on one incision prepreg base material And the other cut prepreg base material are preferably laminated so as to be separated from the geometric center of any cut by 5 mm or more. It is important in two ways that the geometric centers of the notches of adjacent notched prepreg base materials are separated from each other. The first is that when the laminate is stretched during molding, if the cuts are connected to each other, the foamable resin easily enters and tears, and the molding of the present invention may fail. . Moreover, even if it is not torn at the time of molding, there is a possibility of affecting the quality such that the fiber content is lowered and the wall thickness is reduced in the region where the geometric centers of the cut are close to each other. Second, when the fiber reinforced plastic becomes a fiber reinforced plastic, the ends of the reinforced fiber bundles that are cut by the cuts are so-called stress concentration points, so they tend to break, but if the cuts are connected, cracks can easily occur. May be easily connected and the strength may be reduced. FIG. 6 illustrates the relationship between the two layers of the laminated cut prepreg base material, and the geometrical center 8 of the closest cuts among the cuts 4a and 4b in the first layer is shown in FIG. ) To d), preferably 5 mm or more away, both the concerns during molding and the physical properties can be cleared without problems, but when approaching 5 mm as shown in FIG. 6a) The problem may come up. The “geometric center” mentioned here is a point where the first moment is zero around the geometric center point g, and the geometrical center point g is expressed by the following equation for the point x on the notch.

  In order to obtain a cut prepreg base material according to the present invention, as a method of cutting into the prepreg base material, first, a prepreg base material of continuous fibers aligned in one direction is prepared, and then manual operation using a cutter is performed. A method of cutting with a cutting machine or a cutting machine, or a continuous roller prepreg base material manufacturing process that is aligned in one direction, continuously pressing a rotating roller with a blade placed at a predetermined position, or prepreg base material in multiple layers There is a method such as pressing and cutting with a mold in which blades are arranged at predetermined positions. The former is used when making a cut into a part of the prepreg base material easily at the molding site, and the latter is used when making a large amount of the cut prepreg base material in consideration of production efficiency. Is suitable. When a rotating roller is used, the roller may be directly cut out to provide a predetermined blade, but by cutting a flat plate around a magnet roller or the like and winding a sheet-shaped mold with the blade placed at a predetermined position The replacement of the blade is easy and preferable. By using such a rotating roller, it is possible to insert the cut well even with a cut prepreg base material having a small Ws (specifically, 1 mm or less). After making the cut, the cut prepreg base material may be further thermocompression-bonded with a roller or the like, so that the cut portion is filled with a resin and fused, thereby improving the handleability.

  The characteristics of the fiber reinforced plastic obtained by molding according to the present invention using an example of the cut prepreg base material thus obtained will be described with reference to FIG. A part of the laminate 12 in which the cut prepreg base material 10 in which the cut 4 crosses the fiber 3 in the 90 ° direction is laminated is a), and the core-sheath fiber obtained by molding the laminate 12 according to the present invention. A plan view in which a portion of the reinforced plastic sheath 33 isotropically expanded is shown in b) with a close-up of the layer derived from the cut prepreg base material 10 and a cross-sectional view taken along the line AA of the plan view. Indicated. The cut prepreg base material 10 in FIG. 7a) is provided with cuts perpendicular to the fibers as shown in FIGS. 3a) to 3c), and the cuts 4 penetrate in the thickness direction of the layers. By setting the fiber length L to 100 mm or less, the fluidity is ensured, and the sheath part 33 whose area is easily extended from the laminate 12 can be easily obtained (however, the thickness is reduced). When the elongated sheath portion 33 is obtained as shown in FIG. 7b), the short fiber layer 17 derived from the cut prepreg base material 10 extends in the fiber vertical direction, and the region (cut opening portion) 18 in which no fiber exists. Is generated. This is because the reinforcing fiber generally does not expand at a pressure of the molding level. In the case of FIG. 7, the cut opening 18 is generated by the extended length. As shown in the cross-sectional view, the region 18 is occupied by the adjacent layer 19 that has entered, and the substantially triangular resin-rich portion 20 and the region in which the adjacent layer 19 has entered. For example, when a cut prepreg base material that has been cut into the entire surface is disposed on the surface layer of the sheath, the laminate cut opening 18 is observed in the region where the fibers flow as shown in FIG. There is. More preferably, all the layers constituting the fiber reinforced plastic are made of a strip-shaped aggregate having a fiber length Lc in the range of 10 to 100 mm and a width Wsc of 30 μm to 150 mm. In the present invention, as shown in a region 38 surrounded by a dotted line in FIG. 7, a region surrounded by two pairs of fiber bundle dividing portions 22 is expressed as a strip shape. The strip-shaped width Wsc, which is the spread width in the vertical direction of the fiber after molding, is extended to a maximum of about 50% by molding with respect to the projected length Ws obtained by projecting the cut of the notched prepreg base material in the vertical direction of the reinforcing fiber. Therefore, Wsc is in the range of 30 μm to 150 mm.

  As the cut prepreg base material suitably used in the present invention other than the cut prepreg base material whose incision is perpendicular to the fibers as shown in FIGS. 3a) to 3c), as shown in FIGS. It is good to incline from the fiber orthogonal direction 2. When making an incision with a rotating roller or the like industrially, if an attempt is made to make an incision in the fiber orthogonal direction 2 to the prepreg base material supplied in the fiber direction, it is necessary to divide the fiber at once, a large force is required, The durability of the blade is reduced, and the fibers easily escape in the orthogonal direction 2, resulting in an increase in the amount of uncut fibers. On the other hand, since the incision is inclined from the fiber orthogonal direction 2, the amount of fibers to be cut per unit length of the blade is reduced, the fibers can be cut with a small force, the durability of the blade is high, and the uncut fibers can be reduced. Further, since the incision is inclined from the fiber orthogonal direction 2, the projection length Ws obtained by projecting the incision in the vertical direction of the reinforcing fiber can be made smaller than the incision length, and the cutting is divided by each incision. The strength is expected to be reduced by reducing the amount of fibers produced. When cutting in the fiber orthogonal direction 2, it is preferable to prepare a small blade in order to reduce Ws. However, if it is too small, there may be a problem in durability and workability.

  Still another preferred form of the cut prepreg base material is a cut prepreg base material in which the absolute value of the angle Θ formed by the cut with the reinforcing fiber is in the range of 2 to 25 °. In the case of this cut prepreg base material, it is intermittent cut and the angle Θ formed by the cut with the reinforcing fiber is small, as shown in FIG. 10, or continuous cut as shown in FIG. But it ’s okay. 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, even 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 angle of cut with respect to the fiber becomes smaller, the fiber easily escapes from the blade when making the cut, and in order to make the fiber length L 100 mm or less, the absolute value of Θ is 2 °. If it is smaller, at least the shortest distance between the cuts may be less than 0.9 mm, resulting in poor production stability. In addition, when the distance between the cuts is small as described above, there may be 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 °.

  The incision may be a curve as shown in FIG. 11c), but a straight line 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. 11b), but the fluidity is controlled when the fiber length L is constant over the entire surface as shown in FIG. 11a). It is preferable because it is easy and can further suppress variation in strength. Here, the prescribed linear shape means a state in which a part of a geometrical straight line is formed, but unless the effect of facilitating the control of the fluidity is impaired, the geometrical 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 preferable example [1], as shown in FIG. 9 and FIGS. In the pattern of Example [1], since the cut 4c is not intermittent, flow disturbance does not occur in the vicinity of the cut end, and in the region where the cut 4c is made, all the fiber lengths L can be made constant, The flow is stable. When the cut is provided on the entire surface of the prepreg base material, since the cuts 4c are continuously formed, the cut prepreg base material 10 is cut into the peripheral portion of the cut prepreg base material in order to prevent the cut prepreg base material 10 from being separated. It is possible to improve the handleability by providing a region where no is connected, or by gripping it with a support such as a sheet-like release paper or film that is not cut. Moreover, in order to improve the handleability at the time of lamination | stacking, as a two-layer laminated body which laminated | stacked the said cut prepreg base material which cut | incised continuously beforehand like FIG. Also good.

In addition, as another preferable example [2], as shown in FIG. 10, when the length 9 projected in the vertical direction of the reinforcing fiber is Ws, intermittent cuts 4d in which Ws is in the range of 30 μm to 100 mm are provided. The notch prepreg base material 10 is provided on the entire surface, and the notch 4d ₁ and the notch 4d ₂ adjacent in the fiber longitudinal direction of the notch 4d ₁ may have the same geometric shape. FIG. 10 shows an example in which both L and Ws are one type. Any of the cuts 4d (for example, 4d ₁ ) has another cut 4d (for example, 4d ₂ ) that overlaps by translating in the fiber direction. The fiber length can be stably increased by the presence of the width 5 in which the fibers are divided by the adjacent incisions at a fiber length shorter than the fiber length L divided by the cuts 4d that form pairs in the fiber direction. The cut prepreg base material 10 can be manufactured at 100 mm or less. In the pattern of Example [2], when the obtained cut prepreg base material 10 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.

  The characteristics of the sheath portion 33 of the fiber-reinforced plastic having the core-sheath structure obtained by molding according to the present invention using the cut prepreg base material of the preferable example [1] obtained in this way are described with reference to FIG. explain. A part of a laminate 12 in which the cut prepreg base material 10 according to the present invention is laminated is a), and the sheath 33 of the fiber-reinforced plastic having a core-sheath structure obtained by molding the laminate 12 according to the present invention A partially expanded view b) shows a plan view in which the layers derived from the cut prepreg base material 10 are respectively close-up, and a cross-sectional view taken along the line AA of the plan view. As shown to a), the notch prepreg base material 10 is provided with the notch 4c whose angle with the fiber 3 is 25 degrees or less over the entire surface, and the notch 4c penetrates the thickness direction of the layer. By setting the fiber length L to 100 mm or less, the fluidity is ensured, and the sheath portion 33 whose area is extended from the laminate 12 can be easily obtained. When the elongated sheath portion 33 is obtained as in b), the short fiber layer 17 derived from the cut prepreg base material 10 extends in the fiber vertical direction, and the fiber 3 itself rotates 24 to expand the area of the elongated region. As shown in FIG. 7, the region (cut opening) 18 where no fiber is present is not substantially generated, and the area of the surface of the layer of the cut opening is 10% or less compared to the surface area of the layer. . Therefore, as can be seen from the cross-sectional view, the adjacent layer 19 does not penetrate, and the highly rigid and high quality sheath portion 33 having no layer undulation or resin rich portion can be obtained. Since the fibers 3 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. A further epoch-making effect that this fiber rotates and stretches to obtain a sheath portion without layer waviness can be obtained only when the absolute value of the angle Θ formed with the cut fiber is 25 ° or less. Further, 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 22 lies down with respect to the load direction as shown in FIG. I can see the situation. Since the fiber bundle end portion 22 is slanted in the layer thickness direction, load transmission is smooth, and peeling from the fiber bundle end portion 22 hardly occurs. Therefore, further improvement in strength is expected compared to FIG. The fiber bundle end 22 is inclined in the layer thickness direction because when the above-mentioned fiber rotates, there is a gentle distribution in the rotation 24 of the fiber 3 from the upper surface to the lower surface due to friction between the upper surface and the lower surface. It is considered that the presence distribution of the fibers 3 occurs in the layer thickness direction, and the fiber bundle end 22 is inclined in the layer thickness direction. In such a layer of the sheath part 33, a further breakthrough effect of significantly increasing the strength by forming an oblique fiber bundle end in the layer thickness direction is that the absolute value of the angle Θ formed with the fiber 3 of the cut 4c is It can be obtained for the first time when the angle is 25 ° or less.

  On the other hand, in FIG. 13, a part of the laminate 12 in which the cut prepreg base material 10 of the preferred example [2] is laminated is a), and the sheath portion 33 of the fiber reinforced plastic formed from the laminate 12 isotropic. A plan view showing a close-up of a layer derived from the cut prepreg base material 10 is shown in part b). As shown in a), the cut prepreg substrate 10 is provided with intermittent cuts 4d having an absolute value of the angle Θ between the fibers 3 of 25 ° or less, and the cuts 4d penetrate the thickness direction of the layer. ing. By setting the fiber length L to 100 mm or less over the entire surface of the cut prepreg base material 10 by the cut 4d, the fluidity is ensured and the sheath portion 33 of fiber reinforced plastic whose area is easily extended from the laminate 12 is obtained. Can do. By reducing the cut length and the cut angle, the projected 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 elongated fiber-reinforced plastic sheath 33 is obtained as in b), the short fiber layer 17 derived from the cut prepreg base material 10 does not stretch in the fiber direction when stretched in the fiber vertical direction. A region 18 where the fibers do not exist (cut opening portion) 18 is generated, but the adjacent short fiber group flows in the fiber vertical direction, thereby filling the cut opening 18 and reducing the area of the cut opening 18. This tendency is particularly remarkable when the projection 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 18 is not substantially generated, and the layer of the cut opening 18 is not formed. The area on the surface can be in the range of 0.1 to 10% compared to the surface area of the layer. Accordingly, the sheath layer 33 of the fiber reinforced plastic having high rigidity, high strength and high quality without the undulation of the layer and the resin rich portion can be obtained without the adjacent layer entering in the thickness direction. Since the fibers 3 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 18 with the flow in the vertical direction of the fiber to obtain a sheath portion without layer undulation has an absolute value of the cut angle Θ of 25 ° or less and the cut in the vertical direction of the reinforcing fiber. It can be obtained for the first time when the projected length Ws is 1.5 mm or less. More preferably, when Ws is 1 mm or less, higher rigidity, higher strength, and higher quality can be obtained, and application as an outer plate member is also possible.

  Furthermore, it is preferable for the fluidity improvement that the laminate is composed only of the cut prepreg base material. More preferably, the laminate is composed of only a cut prepreg base material, and all the fiber lengths L of the reinforcing fibers constituting the cut prepreg base material are within a range of 10 to 100 mm. Making the incision according to the shape is very time-consuming in terms of design and work. For quality stability, the entire surface is incised so that any area of the laminate can easily follow the complicated shape. It is preferable to keep it.

  Examples of the reinforcing fibers used for the cut prepreg base material according to the present invention include, for example, organic fibers such as aramid fibers, polyethylene fibers, polyparaphenylene benzoxador (PBO) fibers, glass fibers, carbon fibers, silicon carbide fibers, Examples include inorganic fibers such as alumina fibers, Tyranno fibers, basalt fibers, ceramic fibers, metal fibers such as stainless steel fibers and steel fibers, and other reinforcing fibers using boron fibers, natural fibers, modified natural fibers, etc. . 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.

  Examples of the thermosetting resin used for the cut prepreg base material according to the present invention include an epoxy resin, an unsaturated polyester resin, a vinyl ester resin, a phenol resin, an epoxy acrylate resin, a urethane acrylate resin, a phenoxy resin, an alkyd resin, A urethane resin, a maleimide resin, a cyanate resin, etc. are mentioned. When the thermosetting resin is used for the prepreg base material, the cut prepreg base material has tackiness at room temperature, so when the base material is laminated, it is integrated with the upper and lower base materials by adhesion. Then, it can be molded while maintaining the intended laminated structure. Furthermore, since the cut prepreg base material according to the present invention composed of a thermosetting resin has excellent drapability at room temperature, for example, when molding using a mold having a concavo-convex portion, it follows the concavo-convex in advance. It is possible to easily perform the preliminary shaping. This pre-shaping improves moldability and facilitates flow control. In the present invention, as long as this object is achieved, the matrix resin may contain a thermoplastic resin (for example, 40% by weight or less).

  Moreover, the cut prepreg base material according to the present invention may be in close contact with the tape-like support. The base material into which the cut has been inserted can retain its shape even when all the fibers are cut by the cut, and there is no problem that the fibers fall off during shaping. 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.

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 suitable for the present invention. Can be obtained. Among them, the epoxy resin is most excellent in mechanical properties as a reinforced fiber composite material obtained in combination with carbon fiber.

  As the method of injection foaming in the present invention, as disclosed in JP-A-9-328568, (1) a resin mixed with a thermally decomposable foaming agent that decomposes by heating to generate gas is heated. (2) The resin encapsulating the low-boiling liquid is heated to soften the resin, and the low-boiling liquid is expanded and foamed. (3) A high-pressure gas is applied to the resin on the spot. Examples of the method include mixing and foaming, (4) expanding the resin with a gas generated by the reaction, and (5) mixing and foaming foam beads. Preferred examples include polystyrene foam, polyethylene foam, polypropylene foam, etc. In order to obtain a particularly strong core-sheath structure, the polyurethane resin is produced by carbon dioxide gas generated by the reaction of the polyol of the polyurethane resin (4) and isocyanate. It is preferable to use urethane foam obtained by foaming.

  Specific examples of more preferable production methods will be described below.

  About the laminated body used at the shaping process of (1), it is preferable to divide roughly and take the following two methods. The first is a method of forming a prepreg base material by sequentially shaping it on a mandrel, and the second is a method of forming a prepreg base material by laminating it in a flat plate shape. The first method is to directly form a laminate on a mandrel, which is an approximate shape of fiber-reinforced plastic, which is the final shape, and is based on a cut prepreg base using mechanical techniques such as tape layup and sheet winding. Materials and the like may be laminated. Since it is directly formed on a mandrel having a certain shape, wrinkles are hardly generated, and a clean laminate can be formed. The second method is a method in which a prepreg base material such as a cut prepreg base material is first laminated in a flat plate shape, and the laminate is shaped on a mandrel. Work efficiency is good. In the case of a thick laminated body, wrinkles are likely to occur when it is formed on a mandrel having a certain shape although it is a substantial shape. Therefore, it is preferable to heat and soften the laminated body so as not to harden and laminate the laminated body. However, wrinkles at the time of shaping the laminated body are eliminated by appropriately stretching the laminated body at the time of molding.

  To produce a fiber-reinforced plastic with an outer shape of a cylindrical shape (a core-sheath structure consisting of a sheath part having two or more openings for accessing the inner space and a foam material filling the inner space), the laminated body is made of a cylinder without irregularities. It is only necessary to provide the shape on a mandrel, and this is the preferred embodiment of the present invention. For example, as shown in FIG. 14, even if the fiber-reinforced plastic to be manufactured has a complicated shape, if the both ends of the sheath portion are open, a sheet-shaped cut prepreg base material is wound to form a cylinder. If a layered laminate is prepared, it can easily follow a complicated shape. On the other hand, in order to manufacture a fiber-reinforced plastic having a cocoon shape (a core-sheath structure made up of a sheath part having one opening for accessing the internal space and a foam material filling the internal space), the laminate is formed in a bag shape. There is a need. In particular, the present invention is characterized in that the laminate is molded while being stretched. Therefore, if one end of the hole of the cylindrical laminate is closed to form a bag shape, the laminate is easily closed when the laminate is stretched. There is a risk that the hole will open. Therefore, in the molding step, it is preferable to expand the expandable mandrel after pressing and fixing at least one portion of the laminate to the mold. That is, when a bag-like laminate is stretched, a region where a hole is easily opened is pressed against a mold in advance so that the region is not expanded and a hole is not formed. This effect can be further enhanced by arranging fibers having a fiber length of 100 mm or more in the area to be pressed. Specifically, in the case of the collar shape of FIG. 1, only the neck portion 31 and the bottom portion 30 are pressed against the mold first to fix the laminate, and the sheath is made of the laminate. A fiber-reinforced plastic can be manufactured without making a hole in the part.

  Further, by using the present invention, it is possible to preferably form a cylindrical shape having a cross-sectional shape surrounded by a large R and a small R, such as a wing shape. Once the cylindrical laminated body is crushed up and down to make an elliptical shape, it is placed in a wing-shaped cavity. Since the laminate is made smaller than the outer shape of the obtained fiber reinforced plastic, it can be easily set in the cavity. Next, by injecting the foamed resin into the laminated body, pressure is applied evenly to every corner, and the laminated body is firmly pressed against a small R portion that is difficult to follow, so that a high-quality fiber-reinforced plastic can be obtained.

  In addition, so-called draw bending, which is used when bending a metal extruded material or the like, can also be applied to the fiber-reinforced plastic manufacturing method of the present invention. In the shaping process, after providing a laminate to a flexible mandrel (e.g., solid silicon rubber), bending while softening by heating or the like, removing the mandrel, and then placing it in a molding die in the molding process, Molding can be performed by injecting a foamable resin and stretching the laminate.

  More preferably, so-called pultrusion molding, in which a fiber-reinforced plastic having a cylindrical core-sheath structure is obtained by continuously performing a shaping step, a molding step, and a demolding step while taking up the laminate. A fiber-reinforced plastic having a core-sheath structure can be obtained continuously, and is one of the lowest cost molding methods among the molding methods of the present invention.

  More preferably, in the molding process, it is preferable to obtain a fiber-reinforced plastic having a cylindrical core-sheath structure continuously, and by pressing the molding process in such a manner, the mold is continuously pressed into a deformed cross section. As a result, it is possible to obtain a fiber-reinforced plastic having a cylindrical sheath-shell structure with a continuously deformed cross section. In FIG. 15, the laminated body 12 made of only a cut prepreg base material with cuts on the entire surface is continuously supplied, bent by a guide-shaped mandrel 36 a, and ends of the laminated body 12 by a spiral guide 34. In the illustrated embodiment, the foamed resin 27 is drawn into the preheating mold 28c while being overlapped, and the foamable resin 27 is injected into the closed space surrounded by the laminate 12 through the injection port 26. The preheating mold 28 c applies preheating to the laminate 12 to soften it, and the laminate 12 is stretched by the foaming pressure of the foamable resin 27. The movable die 35 is temperature-controlled at a temperature equal to or higher than that of the preheating die 28c, and the fiber-reinforced plastic 16 having a core-sheath structure with an irregular cross section is formed while the movable die 35 is operated. Even with irregularly changing cross-sectional shapes, by using the molding method of the present invention, the same cut prepreg base material can be laminated without preparing many kinds of prepreg base materials with particularly complicated cut patterns. By using the laminated body, a fiber-reinforced plastic having a core-sheath structure with an irregular cross section can be obtained with high efficiency.

  As the molding conditions of the present invention, it is preferable that the mold temperature T1 in the molding process and the mold temperature T2 in the demolding process are substantially constant. The temperature of the mold is represented by the average of the temperatures measured by a thermocouple at a plurality of points on the surface of the cavity that touches the laminate (when there are upper and lower molds, at least one point is measured). Here, that the mold temperature T in the present invention is substantially constant means that the variation of the mold temperature is usually within a range of ± 10 ° C. Further, both T1 and T2 should not change over time. By using a thermosetting resin for the prepreg base material, it is possible to remove the mold while maintaining the mold temperature T, and production is greatly achieved by reducing the cycle time by eliminating the time for raising and lowering the mold temperature. Improves.

In the present invention, the fiber reinforced plastic has a mold temperature T with respect to an exothermic peak temperature Tp based on differential scanning calorimetry (DSC) of a thermosetting resin used for a prepreg substrate.
Tp−60 ≦ T ≦ Tp + 20 (I)
It is preferable to manufacture within the range. More preferably,
Tp-30 ≦ T ≦ Tp (II)
Is within the range. When the mold temperature T is lower than Tp-60, the time required for curing of the resin becomes very long, and the curing may be insufficient. On the other hand, when it is higher than Tp + 20, a rapid reaction of the resin may cause generation of voids inside the resin and poor curing. In addition, exothermic peak temperature Tp based on DSC in this invention was performed according to JISK7121 (1987), and it heated up on the conditions of the temperature increase rate of 10 degree-C / min at the temperature of 30-180 degreeC. This is a value obtained by taking the peak of the exothermic curve. The test piece referred to in JIS K 7121 (1987) is a paste in the present invention. Therefore, “condition adjustment of test piece” and “test piece” can be referred to as “condition adjustment of paste” and “paste”, respectively. In principle, the state of the paste is adjusted to stand for 6 to 8 hours at a temperature of 23 ± 2 ° C. and a relative humidity of 50 ± 5%, and no heat treatment or the like is performed. In addition, since the paste is measured in the form of a paste, there is no regulation regarding the dimensions.

  In the present invention, the thermosetting resin preferably has a minimum viscosity of 0.1 to 100 Pa · s based on dynamic viscoelasticity measurement (DMA). More preferably, it is 0.1-10 Pa.s. When the minimum viscosity is less than 0.1 Pa · s, only the resin flows during pressurization, and the reinforcing fiber may not be sufficiently filled up to the tip of the protrusion. On the other hand, when the viscosity is higher than 100 Pa · s, the fluidity of the resin is poor, and thus the reinforcing fibers and the resin may not be sufficiently filled up to the tip of the protrusion. The minimum viscosity due to DMA in the present invention is a rotational viscometer, using parallel plates with a radius of 20 mm, a distance between parallel plates of 1 mm, a measurement start temperature of 40 ° C., and a temperature increase rate of 1.5 ° C./min. Measured under the condition of a measurement frequency of 0.5 Hz, the value of the lowest viscosity observed.

  As one preferred application example of the fiber reinforced plastic obtained in the present invention, it is preferable that a continuous fiber reinforced plastic composed of continuous fibers and a thermosetting resin is further integrated around the fiber reinforced plastic. . That is, as shown in FIG. 7, in the fiber reinforced plastic manufactured according to the present invention, the fiber bundle dividing part 22 and the cut opening 18 resulting from the cut may be generated on the surface. Failure may also be caused by stress concentration against the load. Therefore, once the fiber reinforced plastic is manufactured according to the present invention, by integrating the fiber reinforced plastic composed of continuous fibers on the surface, at least the surface has a high strength without a fiber bundle splitting portion that is a stress concentration source Fiber reinforced plastic can be obtained. As described above, it is difficult to fabricate a fiber-reinforced plastic composed of continuous fibers into a complex shape. After a fiber-reinforced plastic having a core-sheath structure is manufactured by the manufacturing method of the present invention, a core-sheath structure is obtained. RTM (resin injection molding) by placing a continuous fiber base not impregnated with resin on top of the fiber reinforced plastic, or cocure with a continuous fiber prepreg base, or bonding a continuous fiber prepreg base By integrating and co-bonding together with the agent, it can be integrated with a fiber reinforced plastic made of continuous fibers, and a complex-shaped high-strength fiber reinforced plastic can be manufactured at low cost.

  Further, the assembly cost can be reduced by embedding, hardening, and integrating the metal insert in the discontinuous portion 37 of the laminate 12 shown in FIG. 4 for the purpose of providing a mechanism such as a rotating portion. At that time, by providing a plurality of recesses around the metal insert, the flowed fibers can enter the recesses, and can easily fill the gaps. And can be firmly integrated.

  The fiber reinforced plastic manufactured according to the present invention is used for bicycle members, shafts and heads of sports parts such as golf equipment and golf, automobile parts such as doors and seat frames, and robots that require strength, rigidity, and lightness. There are mechanical parts such as arms. In particular, in addition to strength and light weight, the shape of the member is complicated, and it can be preferably applied to automobile parts such as seat panels and seat frames that require shape followability like this material.

  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.

Example 1
<Preparation of prepreg base material>
An epoxy resin composition was obtained by the following procedure.

  (A) Epoxy resin (“Epicoat (registered trademark)” 828: 30 parts by weight, Epicoat 1001: 35 parts by weight, Epicoat 154: 35 parts by weight) manufactured by Japan Epoxy Resin Co., Ltd., and thermoplastic resin polyvinyl formal (Chisso ( "Vinylec (registered trademark)" K) 5 parts by weight was stirred for 1 to 3 hours while heating at 150 to 190 ° C to uniformly dissolve polyvinyl formal.

  (B) After lowering the resin temperature to 55 to 65 ° C., 3.5 parts by weight of a curing agent dicyandiamide (DICY7 manufactured by Japan Epoxy Resin Co., Ltd.) and a curing accelerator 3- (3,4-dichlorophenyl) -1, 4 parts by weight of 1-dimethylurea (DCU99 manufactured by Hodogaya Chemical Co., Ltd.) was added, kneaded at the temperature for 30 to 40 minutes, and then taken out from the kneader to obtain an epoxy resin composition.

  The obtained epoxy resin composition was apply | coated on the release paper using the reverse roll coater, and the resin film was produced.

Next, the carbon fiber (tensile strength 4,900 MPa, tensile elastic modulus 235 GPa) aligned in one direction in a sheet shape is laminated with two resin films from both sides of the carbon fiber, heated and pressurized to impregnate the resin composition. Thus, a unidirectional prepreg base material having a carbon fiber basis weight of 150 g / m ² and a resin weight fraction of 33% was produced.

  The exothermic peak temperature Tp according to DSC of the obtained epoxy resin composition was 152 ° C. As a measuring apparatus, DSC2910 (product number) manufactured by TA Instruments Inc. was used, and the measurement was performed under a temperature rising rate of 10 ° C./min.

  The minimum viscosity due to DMA was 0.5 Pa · s. As a measuring device, a dynamic viscoelasticity measuring device “ARES” manufactured by T.A. Instruments Co., Ltd. was used under the conditions of a temperature rising rate of 1.5 ° C./min, a frequency of 0.5 Hz, and a parallel plate (radius 20 mm). The minimum viscosity was determined from the temperature-viscosity relationship curve.

<Introduction of cut into prepreg base material>
A cut prepreg base material having regular cuts at regular intervals was obtained by inserting cuts as shown in FIG. 16 into the prepreg base material using an automatic cutter. The cutting direction is the fiber orthogonal direction 2, the cutting length W is 10.1 mm (that is, Ws = 10.1 mm), and the interval L (fiber length) is 30 mm. As shown in FIG. 16, adjacent cut rows 7a and 7b are geometrically equivalent when moved 10 mm in the direction perpendicular to the fiber. In addition, there are pairs of cuts 7a and 7c and 7b and 7d in the cut rows that are paired in the fiber longitudinal direction, and there are two patterns of cut rows. Furthermore, the range of 5 in which the cuts in the adjacent rows cut into each other is 0.1 mm.

<Preparation of foamable resin>
The raw material of the foamable resin 27 forming the urethane foam was prepared and prepared at the following mixing ratio.

  Organic polyisocyanate A: Cosmonate M-200 (Organic polyisocyanate manufactured by Mitsui Takeda Chemical Co., Ltd. NCO% = 31.4%).

  Polyol X: Polyol A, Polyol B, and Polyol C described below in a mixed polyol ratio of 28:12:60 (polyol manufactured by Mitsui Takeda Chemical Co., Ltd., hydroxyl value 350 mgKOH / g).

  Polyol A: A polyol having a hydroxyl value of 350 mgKOH / g obtained by adding propylene oxide to pentaerythritol at a reaction temperature of 110 ° C. using potassium hydroxide as a catalyst.

  Polyol B: A polyol having a hydroxyl value of 350 mgKOH / g obtained by adding propylene oxide to a 70:30 weight ratio mixture of tolylenediamine and triethanolamine at a reaction temperature of 110 ° C. using potassium hydroxide as a catalyst.

  Polyol C: A polyol having a hydroxyl value of 350 mgKOH / g, obtained by adding propylene oxide to a 97: 3 weight ratio mixture of sorbitol and water at a reaction temperature of 110 ° C. using potassium hydroxide as a catalyst.

Catalyst A: Kaulizer No. 10 (N, N-dimethylcyclohexylamine manufactured by Kao Corporation).
Silicone foam stabilizer A: X-20-1328 (polydimethylsiloxane derivative manufactured by Shin-Etsu Chemical Co., Ltd.).

<Molding of fiber-reinforced plastic with core-sheath structure>
As shown in FIG. 17b), a fiber-reinforced plastic having a core-sheath structure like a tank having an overall length of 300 mm, a tube diameter of 50 mm, and a maximum radius of 75 mm and a center inflated was molded. The cut prepreg base material was cut to a width of 300 mm and wound around a mandrel made of a cylindrical iron core with a radius of 47.6 mm. With the longitudinal direction of the cylindrical shape being 0 °, the cut prepreg base material is cut in the orientation direction of the carbon fiber (0 ° direction) and the direction shifted 45 degrees to the right from the orientation direction of the carbon fiber (45 ° direction) 45/0 / −45 / 90] Sixteen layers were laminated so that there was no wrinkle in a laminated structure of _2s , and each layer was made to have no overlap at the beginning and end of winding (the thickness of each layer was constant). In addition, the winding start position was shifted by 5 mm to prevent the edge of the cut prepreg base material from overlapping each layer. Thus, the laminated body provided on the mandrel was removed from the mandrel.

  The mold is composed of molds (mold 28a and mold 28b). The cavity 29 when both molds are combined is designed to determine the outer shape of the final molded product, and a deaeration port 41 is provided at the top. It was. The temperature was controlled at 150 ° C. so that the temperature T1 of the mold in the molding step was substantially the same as the exothermic peak temperature Tp due to DSC of the epoxy resin composition used for the prepreg substrate. A sealing lid 25 made of cylindrical silicon rubber having a radius of 47.6 mm was fitted so as to cover from both ends of the laminated body 12 according to the inner diameter of the laminated body 12. The upper sealing lid 25 has an inlet 26 through which a foamable resin 27 is injected later. After the laminate 12 integrated with the sealing lid 25 was placed in the cavity 29, both molds were closed. The upper and lower gaps of the mold were pressed by the sealing lid 25 and the laminate 12 and sealed so that the foamable resin 27 did not leak from the upper and lower sides of the mold.

  A foamable resin 27 forming a urethane foam was dropped from the inlet 27 and injected and foamed. A mixture of 0.8 parts by weight of catalyst A, 2 parts by weight of silicone foam stabilizer A, and 5 parts by weight of water, and an NCO / OH equivalent ratio of 1.1 with respect to 100 parts by weight of polyol X After mixing 173.5 parts by weight of organic polyisocyanate A and adding 800 g from the inlet 26, the inlet 26 was sealed. The foamable resin 27 immediately foamed, and the laminate 12 was stretched while forming a urethane foam, and the laminate 12 was pressed against the mold 28. After leaving in the mold 28 for 30 minutes, the mold 28 was opened at 150 ° C. without lowering the temperature T2 of the mold in the demolding process from T1, and the fiber-reinforced plastic 16 having the core-sheath structure was demolded.

  A tank-like fiber-reinforced plastic along the outer shape of the mold was obtained. The core portion 33 made of a hard foam material and the smooth and warp-free sheath portion 32 are integrated into a highly rigid and lightweight fiber-reinforced plastic. A strip-shaped fiber bundle having a distribution in which the fiber length Lc is about 30 mm and the width Ws is about 11 to 15 mm around the maximum stretched maximum radius, between the fiber bundle end portions divided by the cut. Were distributed almost evenly. In the upper and lower mouth portions of the fiber reinforced plastic, the cut was not opened because the laminate was not stretched.

(Example 2)
A prepreg base material was prepared in the same manner as in Example 1, and a cut was introduced to prepare a cut prepreg base material. Next, as shown in FIG. 18 a), when producing a laminate, the end of the cut prepreg base material is shifted to form a 16-layer pseudo-isotropic ([45/0 / −45 / 90] _2s ) flat plate shape. Laminated. The cut prepreg base material had a width of 300 mm, and the length was 299 mm when the laminated body was arranged on the mandrel. The 45 ° layer that came to the innermost side (mandrel side) was cut long by 1 mm thereafter. At one end of the laminate, the width of the cut prepreg base material was matched and laminated by offsetting by 5 mm in the length direction to obtain the 16-layer pseudo-isotropic laminate. The laminated body thus obtained was wound on the same mandrel as in Example 1 while warming with a dryer. As in Example 1 in which the prepreg base material was wound one layer further, although slight wrinkles were generated, the end portions of the respective layers were shifted by 5 mm as shown in FIG. Thereafter, molding was performed in the same manner as in Example 1 to obtain a fiber-reinforced plastic.

  The obtained fiber reinforced plastic was molded into a shape as designed in the same manner as in Example 1. The surface was smooth and free of warping. A strip-shaped fiber bundle having a distribution in which the fiber length Lc is about 30 mm and the width Ws is about 11 to 15 mm around the maximum stretched maximum radius, between the fiber bundle end portions divided by the cut. Were distributed almost evenly. In the upper and lower mouth portions of the fiber reinforced plastic, the cut was not opened because the laminate was not stretched.

(Example 3)
In the same manner as in Example 1, a prepreg base material was produced. A linear notch in the direction of 10 ° was continuously inserted into the prepreg base material from the fiber as shown in FIG. 9 using an automatic cutter. As shown in FIG. 19, the cut prepreg base material obtained in this manner was laminated on the front and back so that the fiber directions were the same and the cuts intersected (in the directions of 10 ° and −10 °). The cut prepreg base material was prevented from falling apart. This two-layer laminate is laminated in the form of a plate in a pseudo isotropic manner ([45/45/0/0 / −45 / −45 / 90/90] _S ) in the direction of each of eight sets. According to each orientation, when the laminated body was disposed on the expandable mandrel with a width of 180 mm, the innermost 45 ° layer was cut out by 299 mm, and thereafter every 2 layers was cut out by 2 mm longer. At one end of the laminate, the width of the two-layer laminate was matched and laminated with an offset of 5 mm in the length direction to obtain the 16-layer pseudo-isotropic laminate. Thereafter, the laminate was shaped on a mandrel in the same manner as in Example 2. Moreover, it shape | molded like Example 1 and obtained the fiber reinforced plastic.

  The obtained fiber reinforced plastic was molded into a shape as designed in the same manner as in Example 1. Even in the cut portion on the surface, almost no cut opening is seen, and there is almost no region where the reinforcing fiber is not present and the resin is rich, or the reinforcing fiber of the adjacent layer is excluded, and the appearance quality is good. And obtained smoothness. The fiber direction was rotated from the time when the laminated body was arranged, and it was assumed that the rotation cut the filling opening and became a smooth fiber reinforced plastic.

Example 4
A prepreg base material was prepared in the same manner as in Example 1. In this prepreg base material, an automatic cutting machine is used to project a cut in the vertical direction of the reinforcing fiber by intermittently inserting a straight cut of 1 mm in the direction of 20 ° from the fiber as shown in FIG. The projected length Ws was 0.34 mm. The fibers were cut by the pair of cuts 4d ₁ and 4d ₂ , and the fiber length L was 30 mm over the entire surface of the obtained cut prepreg base material. The cut prepreg base material thus obtained was cut out in the same manner as in Example 1, laminated and molded to obtain a fiber reinforced plastic.

  As shown in FIG. 13 b), the obtained fiber-reinforced plastic filled the cut opening 18 while the fiber 3 was slightly swollen, so that the cut opening 18 was hardly seen on the surface. Good appearance quality and smoothness were obtained.

(Example 5)
A cocoon-shaped fiber-reinforced plastic as shown in FIG. 1c) was molded. The shape of the heel was planned to be a sphere formed by rotating an ellipse having a major axis of 180 mm and a minor axis of 60 mm, with a cylindrical neck having a radius of 40 mm and a length of 20 mm. A prepreg base material was prepared in the same manner as in Example 1, and a cut was introduced to prepare a cut prepreg base material. Next, a cut prepreg base material cut into an appropriate size on a cylindrical mandrel having a radius of 38.8 mm is quasi-isotropic ([90 / 0] _4S ), and the laminate 12 was placed in a range of 200 mm from the mandrel tip. Since it is difficult to shape a flat base material into a bag shape, after winding the cut prepreg base material in a cylindrical shape, the cut prepreg base material is folded at the tip of the mandrel while allowing slight wrinkles. The part to be cut with scissors. The mouth thus obtained removed one laminate from the mandrel, and the mouth of the laminate 12 was closed with a sealing lid 25 made of silicon rubber as shown in FIG.

  The mold is composed of molds (mold 28a and mold 28b). The cavity 29 when both molds are combined is designed to determine the outer shape of the final molded product, and a deaeration port 41 is provided at the top. It was. It arrange | positioned so that the front-end | tip 30 of a laminated body may contact the cavity of the shaping | molding die 28 temperature-controlled so that T1 may be 150 degreeC. The opening of the mold 28 was pressed by the sealing lid 25 and the laminate 12 and sealed so that the foamable resin 27 did not leak. After the upper and lower molds were closed and fixed, the same foamable resin 27 as in Example 1 was injected from the injection port 26 at a pressure of 0.3 MPa. The foamable resin 27 immediately foamed to stretch the laminate 12 while forming a urethane foam, and pressed the laminate 12 against the mold 28. After leaving in the mold 28 for 30 minutes, the mold 28 was opened at 150 ° C. without lowering the temperature T2 of the mold in the demolding process from T1, and the fiber-reinforced plastic 16 having the core-sheath structure was demolded.

  The obtained fiber reinforced plastic had a smooth surface and no warpage as in Example 1. The foam material was harder than Example 1, and became a fiber-reinforced plastic having a very high strength and high rigidity core-sheath structure. As shown in FIG. 8 a), the cut opening 18 where the fiber bundle ends separated by the cut are present apart from each other, and the strip-shaped fiber bundle having a fiber length Lc of 30 mm are distributed almost evenly on the entire surface. It was. The shape and size of the cut openings 18 and the strip-like fiber bundles were different because the stretch ratios were different depending on the regions, but they were regularly arranged. Further, the notch opening portion 18 was hardly seen in the bowl-shaped tip portion 30 that was pressed against the mold, and the fibers did not flow.

(Example 6)
The fiber reinforced plastic 16 having a core-sheath structure with a deformed cross section was continuously drawn using an apparatus as shown in FIG. A prepreg base material was prepared in the same manner as in Example 1, and a cut was introduced to prepare a cut prepreg base material. Next, as shown in FIG. 18 a), when producing a laminate, the end of the cut prepreg base material is shifted to form a 16-layer pseudo-isotropic ([45/0 / −45 / 90] _2s ) flat plate shape. Laminated. The width of the cut prepreg base material was 160 mm at the 45 ° layer that was the innermost (foam material side) at the time of molding. At one end in the width direction of the laminate, the width of the cut prepreg base material was matched and laminated by offsetting by 5 mm in the length direction to obtain the 16-layer pseudo isotropic laminate. The laminated body 12 obtained in this way is continuously supplied to the apparatus, bent by a V-shaped guide-shaped mandrel 36a, shaped into a cylindrical shape by a spiral guide 34, and at the end of the laminated body As shown in FIG. 18b, the laminate 12 having a thickness corresponding to all 16 layers was formed without overlapping. While the foamable resin 27 similar to that in Example 1 is injected into the cylindrical laminate 12 from the injection port 26, foaming is performed in the preheating mold 28c adjusted to 120 ° C., and the laminate 12 is stretched. It was pressed against a movable die 35. The movable die 35 was operated so that the cross-sectional shape continuously changed from the outlet of the preheating die 28c, the temperature was adjusted to 160 ° C., and the fiber reinforced plastic was cured to determine the cross-sectional shape. The cross-sectional shape was rectangular, one width was fixed at 50 mm, and the other width was varied within the range of 45-60 mm. The take-up speed was 10 mm / min, and the maximum fluctuation speed of the two movable parts of the movable die 35 was set so as not to exceed 1/5 of the take-up speed. In this way, a fiber-reinforced plastic 16 having a core-sheath structure with a continuously deformed cross section was obtained.

  The fiber-reinforced plastic thus obtained had a smooth surface and no warpage, as in Example 1. The cut opening 18 in which the fiber bundle ends separated by the cut are present apart from each other, and the strip-shaped fiber bundle having a fiber length Lc of 30 mm are distributed over the entire surface.

(Reference Example 1)
The fiber reinforced plastic with the core-sheath structure of Example 1 was demonstrated to have high mechanical properties with the physical properties of the fiber reinforced plastic in the sheath part, which bears most of the mechanical properties of the core-sheath structure, that is, the flat plate of fiber reinforced plastic. A prepreg base material was prepared in the same manner as in Example 1, and a cut was introduced to prepare a cut prepreg base material. Each was cut into a size of 250 × 250 mm in a carbon fiber orientation direction (0 ° direction) and a direction shifted 45 degrees to the right from the carbon fiber orientation direction (45 ° direction). The cut prepreg base material cut out was laminated in a pseudo isotropic manner with 16 layers ([45/0 / −45 / 90] _2S ) to obtain a laminate.

  Furthermore, after arrange | positioning in the approximate center part on the flat plate metal mold | die which has a cavity of 300x300mm using said laminated body, it is 150 degreeC x 30 minutes under the pressurization of 6 MPa with a heating type press molding machine. The plate was hardened under the above conditions to obtain a flat fiber reinforced plastic of 300 × 300 mm.

  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 specified 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 reference 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. The tensile elastic modulus was 43 GPa, the tensile strength was as high as 370 MPa, and the CV value was 3%, which was a very small variation.

  In the fiber reinforced plastic, the fibers are evenly flowed to the end, and like the first embodiment, a strip-like fiber bundle having a distribution with a fiber length Lc of 30 mm and a width Ws of about 11 to 15 mm is almost on the entire surface. Since it was evenly distributed, it was expected that the fiber reinforced plastic obtained in Example 1 would also exhibit high mechanical properties. In Reference Example 1, the flat plate was molded at a high pressure of 6 MPa, but in Example 1, the laminate could be stretched only with the foaming pressure of the foamable resin. It is also a feature of the present invention that molding is possible even at low pressure.

(Reference Example 2)
The high mechanical properties of the fiber reinforced plastic of Example 3 were demonstrated by the physical properties of the fiber reinforced plastic in the sheath portion, which has most of the mechanical properties of the core-sheath structure, that is, the flat plate of fiber reinforced plastic. In the same manner as in Example 3, a two-layer laminate was obtained. From this two-layer laminate, cut into a size of 250 × 250 mm in each of a carbon fiber orientation direction (0 ° direction) and a direction shifted to the right by 45 degrees from the carbon fiber orientation direction (45 ° direction). A layer stack of 8 layers is laminated in a pseudo isotropic manner ([45/45/0/0 / -45 / -45 / 90/90] _S ) in each direction, and a 250 × 250 mm laminate having a notch on the entire surface. Got the body.

  The laminate thus obtained was press-molded in the same manner as in Reference Example 1 to obtain a flat fiber reinforced plastic. The obtained fiber reinforced plastic was subjected to a tensile test in the same manner as in Reference Example 1. The tensile modulus was 46 GPa and the tensile strength was as high as 470 MPa, and the CV value was 4%, which was very small.

  In the fiber reinforced plastic, the fibers are flowing evenly to the end, almost no cut openings are seen on the surface, and the fiber direction is the same as in Example 3 in the state of rotation from the time when the laminate is arranged. For this reason, it was expected that the cylindrical fiber reinforced plastic obtained in Example 3 would also exhibit high mechanical properties.

(Reference Example 3)
It was demonstrated on a flat plate that the fiber reinforced plastic of Example 4 has high mechanical properties. A cut prepreg base material was obtained in the same manner as in Example 4, cut out, laminated and press-molded in the same manner as in Reference Example 1. When the obtained fiber reinforced plastic was subjected to a tensile test in the same manner as in Reference Example 1, the tensile elastic modulus was 46 GPa, the tensile strength was as high as 620 MPa, and the CV value was 4%, which was a very small variation. . In fiber reinforced plastic, fibers flow evenly to the end, filling the cut openings while the fibers swell slightly, there are almost no cut openings on the surface, and even the cuts are indistinguishable Since the appearance is the same as in Example 4, it was expected that the cylindrical fiber reinforced plastic obtained in Example 4 would also exhibit high mechanical properties.

(Comparative Example 1)
As in Example 1, molding of a fiber-reinforced plastic having a core-sheath structure was attempted using a continuous fiber prepreg base material. In the same manner as in Example 1, a prepreg base material was produced. When producing a laminated body from the prepreg base material obtained in this manner, as shown in FIG. 18 a), the end of the prepreg base material is shifted and pseudo-isotropic ([45/0 / −45 / 90] _2S ) in a flat plate shape. When the prepreg base material had a width of 300 mm and a length of the laminated body arranged on the mandrel, the 45 ° layer that came to the innermost side (mandrel side) was cut out by 299 mm, and thereafter, each layer was cut out by 1 mm longer. At one end of the laminate, the width of the prepreg base material was matched and the laminate was offset by 5 mm in the length direction to obtain the 16-layer pseudo-isotropic laminate. The laminated body thus obtained was wound on the same mandrel as in Example 1 while warming with a dryer. Although wrinkles were generated due to the difference in circumferential length of each layer of the laminate, the molding was carried out in the same manner as in Example 1.

  It was found that the obtained fiber reinforced plastic could be easily removed from the mold, the surface was rough, and the fiber reinforced plastic was not completely adhered to the mold. The cause was thought to be that the fibers were stretched and the laminate could not be stretched and did not conform to the mold.

(Comparative Example 2)
In the same manner as in Example 1, a fiber-reinforced plastic with a core-sheath structure was molded using SMC as a laminate. 100 parts by weight of vinyl ester resin (manufactured by Dow Chemical Co., Ltd., Delaken 790) as a matrix resin of SMC, 1 part by weight of tert-butyl peroxybenzoate (manufactured by NOF Corporation, Perbutyl Z) as a curing agent, 2 parts by weight of zinc stearate (manufactured by Sakai Chemical Industry Co., Ltd., SZ-2000) is used as an internal mold release agent, and 4 parts by weight of magnesium oxide (Kyowa Chemical Industry Co., Ltd., MgO # 40) is used as a thickener. Then, they were sufficiently mixed and stirred to obtain a resin paste. The resin paste was applied onto a polypropylene release film using a doctor blade. From there, carbon fiber bundles (tensile strength 4,900 MPa, tensile elastic modulus 235 GPa, 12,000 fibers) cut to a length of 25 mm are uniformly dropped and dispersed so that the weight per unit area is 500 g / m ^2. did. Further, it was sandwiched between the other polypropylene film coated with the resin paste with the resin paste side inward. The volume content of carbon fiber with respect to the SMC sheet was 40%. The obtained sheet was allowed to stand at 40 ° C. for 24 hours, thereby sufficiently thickening the resin paste to obtain an SMC sheet. This SMC sheet was cut out to a width of 300 mm and wound around the same inflatable mandrel as in Example 1 to obtain a laminate. Thereafter, molding was performed in the same manner as in Example 1 to obtain a fiber-reinforced plastic.

  In the sheath portion of the obtained fiber reinforced plastic, the fibers sufficiently flowed to the end of the cavity. Although there was no warp, some sink marks due to the density of the fibers were observed on the surface. In addition, although there was no place where there was a hole, it was found that there was a part where the wall thickness was extremely thin, and the fluidity was not uniform. Further, since Vf was 40%, it was estimated that the strength was not as high as that of Example 1.

It is sectional drawing which shows an example of the manufacturing method of the fiber reinforced plastics of this invention. It is an enlarged plan view which shows an example of the cutting prepreg base material used for this invention. It is a top view which shows the example of the cutting prepreg base material used for this invention. It is the top view and sectional drawing which show an example of the laminated body used for this invention. It is sectional drawing which shows an example of the mechanism of the flow of the laminated body used for this invention. It is a top view which shows the example of the cutting positional relationship of the laminated body used for this invention. It is the top view and sectional view which show an example of the mode of extension of the layered product used for the present invention. It is the schematic which shows an example of the fiber reinforced plastic manufactured by this invention. It is an enlarged plan view which shows an example of the cutting prepreg base material used for this invention. It is an enlarged plan view which shows an example of the cutting prepreg base material used for this invention. It is a top view which shows the example of the cutting prepreg base material used for this invention. It is the top view and sectional view which show an example of the mode of extension of the layered product used for the present invention. It is a top view which shows an example of the mode of the expansion | extension of the laminated body used for this invention. It is sectional drawing which shows an example of the manufacturing method of the fiber reinforced plastics of this invention. It is sectional drawing which shows an example of the manufacturing method of the fiber reinforced plastics of this invention. It is an enlarged plan view which shows an example of the cutting prepreg base material used for this invention. It is an enlarged view which shows an example of the manufacturing method of the fiber reinforced plastics of this invention. It is sectional drawing which shows an example of the shaping method of the laminated body of this invention. It is a top view which shows an example of the form of the cut prepreg base material used for this invention.

Explanation of symbols

1: Fiber longitudinal direction 2: Fiber orthogonal direction 3: Reinforcing fiber 4: Discontinuous end (cutting) of reinforcing fiber
4a: cut in layer a 4b: cut in layer b 4c (4c ₁ , 4c ₂ ): continuous cut 4d (4d ₁ , 4d ₂ ): intermittent cut 5: width cut into each other 6: in the fiber direction Distance L (fiber length L) between geometric centers of the pair of cuts
7: Row of intermittent notches 7a: Row of first intermittent cuts 7b: Row of second intermittent cuts 7c: Row of third intermittent cuts 7d: Fourth row of intermittent cuts 8: Geometric center of cut 8a: Geometric center of cut of layer a 8b: Geometric center of cut of layer b 9: Projected length Ws obtained by projecting the cut in the vertical direction of the reinforcing fiber
DESCRIPTION OF SYMBOLS 10: Cut prepreg base material 10a: Pre-preg base material with notches in the entire surface 10b: Pre-preg base material with notches in part 11: Pre-preg base material with continuous fiber base material 12: Laminate body 13: Laminate body 14: Flow of resin 15: Opening of end of reinforcing fiber 16: Fiber-reinforced plastic with core-sheath structure 17: Short fiber layer 18: Region where no reinforcing fiber exists (cut opening)
19: Adjacent layer 20: Resin rich portion 21: Layer waviness 22: Fiber bundle end portion 23: Angle Θ formed by notch and fiber direction
24: Rotation of reinforcing fiber 25: Sealing lid 26: Injection port 27: Foamable resin 28: Mold 28a: Mold a
28b: Mold b
28c: Mold for preheating 29: Cavity of molding mold 30: Bottom part of bowl shape 31: Neck part of bowl shape 32: Foam material (core part)
33: Fiber reinforced plastic (sheath)
34: Spiral guide 35: Movable type 36: Mandrel 36a: Guide-shaped mandrel 37: Region in which only cut prepreg base materials in which fibers are cut into a length of 10 to 100 mm by cutting are stacked (laminated body) Discontinuity)
38: Region surrounded by two pairs of fiber bundle splitting portions (strip-shaped fiber bundle)
39: Each layer offset at the end of the laminated body 40: A base material in which two layers of cut prepreg base material are laminated 41: Deaeration port

Claims (12)

Using a prepreg base material composed of reinforced fibers and thermosetting resin aligned in one direction, a closed sheath portion, and a core portion composed of a foam material provided inside the closed shape A method for producing a fiber-reinforced plastic having a core-sheath structure constituted by: cutting at least a part of reinforcing fibers into a length of 10 to 100 mm by a plurality of cuts in a direction crossing the reinforcing fibers as the prepreg base material A method for producing a fiber reinforced plastic, wherein a fiber reinforced plastic is molded through at least the following steps (1) to (3) using an embedded prepreg base material.
(1) A laminate in which a plurality of prepreg base materials including the cut prepreg base material are laminated is provided on a substantially shaped mandrel of the final shape of the fiber reinforced plastic, and is shaped smaller than the final shape of the fiber reinforced plastic. After that, the shaping step for decentering the mandrel (2) The laminated body is placed in a molding die which is an outer mold, and the thermosetting resin of the laminated body is softened by heating to decenter the mandrel. Foamed resin is injected into the location, foamed and cured to form a foam material, and at the same time the core is formed, the laminate is stretched by the foaming pressure of the foamable resin, pressed against a mold and cured, Forming step of forming the sheath portion from the laminate, and molding the sheath portion and the core portion to form a fiber-reinforced plastic having a core-sheath structure (3) Demolding step of taking out the fiber-reinforced plastic from the mold The fiber reinforcement according to claim 1, wherein a region where only the cut prepreg base material in which the reinforcing fibers are cut into a length of 10 to 100 mm is laminated is formed in at least a part of the laminate. Plastic manufacturing method. All of the reinforced fiber which comprises the said cutting prepreg base material is divided | segmented by the said cutting, The fiber length L divided | segmented by the said cutting is in the range of 10-100 mm, The Claim 1 or 2 Manufacturing method for fiber reinforced plastic. The cut of the cut prepreg base material is linear, and the projection length Ws obtained by projecting the cut in the vertical direction of the reinforcing fiber is 30 μm to 100 mm, and is disposed intermittently and periodically over the entire surface. The manufacturing method of the fiber reinforced plastic in any one of Claims 1-3. The notch prepreg base material is adjacent to two or more layers in succession, and any two adjacent layers of the two or more layers are arranged with respect to the geometric center of any notch on one notch prepreg base material and the other The manufacturing method of the fiber reinforced plastics in any one of Claims 1-4 laminated | stacked so that it may leave | separate 5 mm or more from the geometrical center of any notch on a notch prepreg base material. The manufacturing method of the fiber reinforced plastics in any one of Claims 1-5 in which the said notch inclines from the fiber orthogonal direction. The manufacturing method of the fiber reinforced plastics in any one of Claims 1-5 whose absolute value of angle (theta) which the said notch makes with a reinforced fiber is in the range of 2-25 degrees. The manufacturing method of the fiber reinforced plastics in any one of Claims 1-7 with which the said laminated body is comprised only from the said cut prepreg base material. The method for producing a fiber-reinforced plastic according to any one of claims 1 to 8, wherein the laminate used in the shaping step (1) is formed by sequentially shaping the prepreg base material on the mandrel. The laminate used in the shaping step of (1) is formed by laminating the prepreg base material in a flat plate shape, and then the laminate is shaped on the mandrel. The manufacturing method of the fiber reinforced plastic as described in 2 .. The fiber-reinforced plastic according to any one of claims 1 to 10, wherein the steps (1) to (3) are continuously performed while the laminate is taken to obtain a fiber-reinforced plastic having a cylindrical core-sheath structure. Manufacturing method. The method for producing a fiber reinforced plastic according to claim 11, wherein, in the molding step (2), a fiber reinforced plastic having a cylindrical core-sheath structure with a deformed cross section is obtained by pressing against a die that continuously changes into a different shape.

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