JP2007146151A - Prepreg substrate material, laminated substrate material and fiber-reinforced plastic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a prepreg substrate material having good flowability and following property to a complex form, and exhibiting an excellent dynamic property, a low unevenness of the same and an excellent dimensional stability on making it as a fiber-reinforced plastic, and a laminated substrate material of the prepreg substrate material. <P>SOLUTION: This prepreg substrate material constituted with carbon fibers drawn/arranged in one direction and a thermosetting resin, and closely bonded with a tape-formed supporting body is characterized in that a multiple number of rows consisting of notches having 2-50 mm length W are installed in the crossing direction to the fibers over the whole surface of the prepreg substrate material, the interval of the row and the first row overlapping on moving the row in parallel in the longitudinal direction of the fiber is 10 to 100 mm, each of the adjacent rows are shifted in the direction crossing with the fibers at right angle and also the notches of the adjacent rows are cutting-in with each other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention provides a prepreg base material that has good fluidity and molding followability, and exhibits excellent mechanical properties, its low variation, and excellent dimensional stability when used as a fiber-reinforced plastic, and the prepreg base material The present invention relates to a laminated substrate. More specifically, for example, the present invention relates to a prepreg base material that is an intermediate base material of fiber reinforced plastic that is suitably used for automobile members, sports equipment, and the like, and a laminated base material of the prepreg base material.

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

  As a molding method of fiber reinforced plastic having high functional properties, a semi-cured intermediate base material impregnated with matrix resin is laminated on continuous reinforcing fiber called prepreg, and heated and pressurized in a high temperature and high pressure kettle. Autoclave molding in which a matrix resin is cured and a fiber reinforced plastic is molded is most commonly performed. In recent years, for the purpose of improving production efficiency, RTM (resin transfer molding) molding in which a continuous fiber base material previously shaped into a member shape is impregnated with a matrix 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, it is difficult to form a complicated shape such as a three-dimensional shape because it is a continuous fiber, and it is mainly limited to members close to a planar shape.

  As a molding method suitable for a complicated shape such as a three-dimensional shape, there is SMC (sheet molding compound) molding. SMC molding is performed by heating and pressurizing a semi-cured SMC sheet obtained by impregnating a chopped strand cut to about 25 mm with a matrix resin, which is a thermosetting resin, using a heating press. In many cases, before pressing, the SMC sheet is cut smaller than the shape of the molded body, placed on a mold, and stretched (flowed) into the shape of the molded body by pressing to perform molding. Therefore, it is possible to follow a complicated shape such as a three-dimensional shape by the flow. However, since SMC inevitably causes distribution unevenness and orientation unevenness of chopped strands in the sheeting process, the mechanical properties deteriorate or the variation of the values increases. Furthermore, due to uneven distribution and alignment unevenness of the chopped strands, warpage, sink marks and the like are likely to occur particularly in a thin member, which may be unsuitable as a structural material.

  In order to fill in the drawbacks of the above-described materials, a base material is disclosed that can be made fluid and small in variation in mechanical properties by cutting into a prepreg composed of continuous fibers and a thermoplastic resin (for example, patents). Reference 1). However, in Patent Document 1, since a thermoplastic resin is used as a matrix resin, there is a problem that the base material is slipped and laminated structure is not suitable for drape (deformability) due to lack of tackiness (adhesiveness). ) Has a problem that it is difficult to shape a member having an uneven portion.

Furthermore, in the method described in Patent Document 1, there is a possibility that some continuous fibers that are not cut by cutting are present, in which case the fluidity is remarkably inhibited, and the expected effect cannot be obtained. Moreover, even if all the fibers are cut by cutting, the thermoplastic resin is not tacky, so the fibers cannot be connected to each other in the horizontal direction, and the shape cannot be maintained by a tape-like support such as a release paper. For this reason, the fibers fall off during shaping, making it impossible to mold as designed.
Japanese Unexamined Patent Publication No. 63-247010

  In view of the background of such prior art, the present invention has excellent fluidity, complicated shape followability, and exhibits excellent mechanical properties, low variation, and excellent dimensional stability when used as a fiber reinforced plastic. A prepreg base material and a laminated base material of the prepreg base material are provided.

The present invention employs the following means in order to solve such problems. That is,
(1) A prepreg base material composed of carbon fibers and a thermosetting resin aligned in one direction and in close contact with a tape-like support, and intermittent in the direction across the fiber across the entire surface of the prepreg base material A plurality of rows each having a notch with a length W of 2 to 50 mm are provided, and an interval L between the row and the first overlapping row when the row is translated in the fiber longitudinal direction is 10 to 100 mm. A prepreg base material, wherein each adjacent row is shifted in a fiber orthogonal direction, and the cuts in the adjacent row are cut into each other.

  (2) The prepreg base material according to (1), wherein the width of the adjacent cuts in the row is 0.1 mm or more and 0.1 times or less of the shorter one of the adjacent cuts.

  (3) The prepreg base material according to (1) or (2), wherein the shape, size, and direction of the cut are the same.

  (4) The prepreg base material according to any one of (1) to (3), wherein the cuts are continuously distributed at equal intervals along a direction across the fiber.

  (5) The prepreg base material according to any one of (1) to (4), wherein all the cutting directions are orthogonal to the fiber.

  (6) The prepreg base material according to any one of (1) to (5), wherein the number of fibers cut by any one incision is 5000 to 50000.

  (7) When the exothermic peak temperature due to DSC of the thermosetting resin is Tp, the temperature T at which the thermosetting resin can be cured within 10 minutes is within the range of (Tp-60) to (Tp + 20). The prepreg base material according to any one of (1) to (6).

  (8) Any of the above (1) to (7), wherein the thermosetting resin is an epoxy resin containing an amine curing agent as a curing agent and a compound having two or more urea bonds in one molecule as a curing accelerator. The prepreg base material according to any one of the above.

  (9) The prepreg base material according to any one of (1) to (8), wherein the curing accelerator is 2,4-toluenebis (dimethylurea) and / or 4,4-methylenebis (phenyldimethylurea). .

  (10) A laminated substrate obtained by laminating and integrating the prepreg substrates according to any one of (1) to (9).

  (11) In adjacent layers in which the fiber directions are substantially the same, rows of intermittent cuts of the length W of both layers of the prepreg base material are equally spaced, and the prepreg base material of one layer The laminated base material according to (10), wherein the row of the cuts is arranged so as to be shifted in the fiber longitudinal direction with respect to the row of the cuts of the prepreg base material of the other layer.

  (12) The lamination according to (11), wherein the rows formed by the cuts of the prepreg base material of each layer are arranged shifted in the fiber longitudinal direction within a range of 0.1 to 0.5 times the interval L. Base material.

  (13) In adjacent layers in which the fiber directions are substantially the same direction, the prepreg base material of both layers is a row in which the cuts are distributed at equal intervals along the direction across the fiber, and the prepreg of one layer The laminated base material according to (10) or (11), wherein the row of the cuts of the base material is arranged in a fiber orthogonal direction with respect to the row of the cuts of the prepreg base material of the other layer.

  (14) The row formed by cutting the prepreg base material of each layer is arranged so as to be shifted in the fiber orthogonal direction within a range of 0.1 to 0.5 times the length W. Laminated substrate.

  (15) A fiber reinforced plastic obtained by curing the laminated substrate according to any one of (10) to (14).

  (16) It has a planar skin portion and a protrusion on at least one surface of the skin portion, and at least one of the layers constituting the stacked structure of the protrusion has a shape along the shape of the protrusion. The fiber-reinforced plastic as described in (15) above.

  (17) The shape of the protrusion is at least one selected from a plate shape, a rod shape, a hemispherical shape, a polygonal column shape, a columnar shape, a polygonal pyramid shape, a conical shape, and combinations thereof (15) or ( The fiber-reinforced plastic according to 16).

  (18) The fiber-reinforced plastic according to any one of (15) to (17), wherein the height of the protruding portion is 0.5 to 50 times the thickness of the skin portion.

  According to the present invention, when a fiber reinforced plastic has good fluidity and complex shape followability, it has excellent mechanical properties, low variability, and excellent dimensional stability. A laminated base material of a prepreg base material can be obtained.

  The present invention has the above problems, that is, a prepreg base material that has excellent fluidity and complex shape followability, and exhibits excellent mechanical properties, its low variation, and excellent dimensional stability when used as a fiber reinforced plastic, In addition, the laminated base material of the prepreg base material has been studied earnestly, and the prepreg base material has a notch pattern specific to a specific base material called a prepreg base material composed of carbon fibers and a thermosetting resin aligned in one direction. Was inserted, and the prepreg base material was laminated and pressure-molded, and it was found that this problem could be solved all at once.

  The prepreg base material of the present invention is a prepreg base material composed of carbon fibers aligned in one direction as reinforcing fibers and a thermosetting resin as a matrix resin, and is in close contact with a tape-like support.

  By arranging the carbon fibers in one direction, it becomes possible to design a molded body having arbitrary mechanical properties by controlling the orientation in the fiber direction. In the present specification, unless otherwise specified, in the term including fiber or fiber (for example, “fiber direction” or the like), the fiber represents a reinforcing fiber.

  Since the matrix resin is a thermosetting resin, the prepreg base material of the present invention has tackiness at room temperature, so when the base material is laminated, it is integrated with the upper and lower base materials by adhesion, It can be molded while maintaining the intended laminated structure. On the other hand, in the case of a thermoplastic resin prepreg base material that does not have tack at room temperature, the base materials slip when the prepreg base materials are laminated. It becomes reinforced plastic. In particular, when molding with a mold having an uneven portion, the difference appears remarkably.

  Furthermore, since the prepreg base material of 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 part, pre-applying along the concavo-convex part in advance. The shape can be easily done. This pre-shaping improves moldability and facilitates flow control. On the other hand, with a prepreg base material composed of a thermoplastic resin, it is extremely difficult to pre-shape at room temperature.

  In addition, since the prepreg base material of the present invention is in close contact with the tape-like support, the base material into which the cut is inserted can maintain its form even if all the fibers are cut by the cut, There is no problem that the fibers fall off and fall apart during shaping. This adhesion is possible only when the matrix resin is a thermosetting resin having tackiness, and cannot be realized with a prepreg base material composed of a thermoplastic resin having no tackiness. 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.

  Furthermore, the prepreg base material of the present invention is provided with a plurality of rows (7, 8, 9) of rows of notches 4 having a length W of 2 to 50 mm intermittently extending across the fiber on the entire surface of the prepreg base material. The distance L (6 in the figure) between the row and the first overlapping row when the row is translated in the fiber longitudinal direction is 10 to 100 mm, and the adjacent rows are in the fiber orthogonal direction. It is an indispensable requirement that the notches in the adjacent rows are displaced from each other. By inserting cuts that satisfy the above-described conditions on the entire surface of the prepreg base material, the prepreg base material is not composed of continuous fibers but is composed of at least two types of short fibers having different lengths. The short fiber referred to in the present invention has a length of 100 mm or less. By inserting cuts that satisfy the above conditions on the entire surface of the prepreg base material, the fibers can flow during molding, in particular in the longitudinal direction of the fibers, and have excellent complex shape followability. 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.

  When the length of the cut is less than 2 mm, a group of fibers becomes smaller, so the fibers tend to swell due to the flow during molding, and the mechanical properties deteriorate. Since the aggregate of the fibers becomes large, the fluidity of the fibers deteriorates and the variation in mechanical properties also increases. A more preferable incision length is 5 to 30 mm.

  On the other hand, when the distance L between the row and the row that overlaps first when the row is translated in the fiber longitudinal direction is smaller than 10 mm, the length of the fiber is also shortened, so that the reinforcing effect by the fiber is reduced. When a fiber reinforced plastic is used, sufficient mechanical properties cannot be obtained, and when it is larger than 100 mm, fluidity at the time of molding deteriorates and it is difficult to form a complicated shape. The distance L is more preferably 10 to 50 mm. Thus, when both the properties of formability and physical properties are taken into consideration, it is necessary to satisfy the above range. Here, as shown in FIG. 1, the distance L corresponds to the length of a desired short fiber, and hence may be hereinafter referred to as a desired fiber length.

  In addition, when the adjacent rows are not displaced in the fiber orthogonal direction, there are fibers that are not cut by the cutting, and the fluidity of the fibers is significantly lowered.

  Furthermore, in this invention, when the notch | incision of this adjacent row | line | column cuts into each other, it is comprised by the fiber shorter than desired fiber length and desired fiber length, and the fluidity | liquidity of a fiber becomes favorable. On the other hand, when the adjacent row of cuts do not cut each other, fibers that are longer than the desired fiber length are generated without being cut by the cuts, and the fibers significantly impair the fluidity. This is because, in a prepreg having a continuous fiber aligned in one direction as a reinforcing fiber, the fiber is strictly straight in one direction due to the characteristics of the fiber itself and the reason for the prepreg process. This is due to undulation and twisting. For this reason, it is very important to prevent the generation of fibers longer than the desired fiber length by cutting adjacent rows into each other.

  In the prepreg base material of the present invention, it is preferable that the width 5 in which the cuts in the adjacent rows are cut from each other is 0.1 or more and 0.1 times or less of the shorter one of the adjacent cuts. If it is smaller than 0.1 mm, fibers that are longer than the desired fiber length may be generated without being cut by cutting, and this is not preferable because the fibers significantly impair the fluidity. When it is larger than 0.1 times of the shorter one of the adjacent cuts, the ratio of the number of fibers cut into each other relative to the number of fibers cut by any one cut, that is, the ratio of fibers shorter than the desired fiber length is increased. This is not preferable because the mechanical properties of the fiber-reinforced plastic are significantly reduced. The shorter one of the adjacent cuts here does not include the case where the cut is interrupted at the end of the prepreg base material. In such a case, the inner cut that does not cover the end is not included. Shall be judged on the basis of

  The prepreg base material of the present invention preferably has the same shape, size and direction of the cut. The effect of the present invention can be obtained even if the shape, size, and direction of the cut are two or more, but by making all the same, the flow of the fiber becomes uniform, so that the fluidity of the fiber can be easily controlled. The generation of warp is also suppressed, and the design of a molded product having arbitrary mechanical properties is facilitated by controlling the orientation in the fiber direction, which is preferable.

  In the prepreg base material of the present invention, it is preferable that the cuts are continuously distributed at equal intervals along the direction across the fiber. In the case of equal intervals, the flow of the fibers becomes uniform as in the shape, size and direction of the incision described above, so that the fluidity of the fibers can be easily controlled, the generation of warpage is suppressed, and the orientation control in the fiber direction is also performed. Therefore, it is preferable because it becomes easy to design a molded body having arbitrary mechanical properties.

  In the prepreg base material of the present invention, it is preferable that the pattern of the rows formed of the cuts is 2 to 5 patterns. When there is only one pattern of rows formed of the cuts, there are fibers that are not cut by the cuts, and the fluidity of the fibers is significantly reduced. On the other hand, when there are 6 or more patterns of rows formed of the notches, it becomes difficult to control the flow of fibers, and it becomes difficult to form a molded body as designed.

  As for the prepreg base material of this invention, it is preferable that the direction of this notch | incision is all fiber orthogonal directions. When all the cutting directions are orthogonal to the fibers, the length of the cutting required to cut a specific number of fibers is minimized, and the deterioration of mechanical properties can be minimized. Furthermore, in order to make it flow isotropic, it is preferable that all the cutting directions are fiber orthogonal directions.

  In the prepreg base material of the present invention, the number of fibers cut by any one incision is preferably in the range of 5000 to 50000. When the number of fibers is less than 5000 as in the case of the above-mentioned notch length, the fibers are likely to swell due to the flow during molding, and the mechanical properties may be lowered. When the number of fibers is more than 50000, a group of fibers surrounded by notches adjacent to each other in the longitudinal direction of the fiber becomes large, so that the fluidity of the fiber is deteriorated and the variation in mechanical properties is increased. Absent.

The laminated substrate of the present invention is preferably obtained by laminating and integrating the prepreg substrates. The laminated structure is not particularly limited as long as it is a laminated structure suitable for each application, but [+ 45/0 / −45 / 90] _S , [0 / ± 60] _S , etc. This method is preferable when uniform physical properties are used and generation of warpage is suppressed. Furthermore, by integrating, the handleability at the time of shaping | molding improves, Furthermore, it can shape | mold, maintaining the laminated structure as designed. Since the matrix resin of the prepreg base material of the present invention is a thermosetting resin, it has tackiness, and the base materials can be easily integrated by adhesion.

  In the laminated base material of the present invention, in adjacent layers in which the fiber directions are substantially the same direction, rows of intermittent cuts of the length W of both layers of the prepreg base material are equally spaced, It is preferable that the row | line | column which consists of the said cut | notch of a layer is shifted | deviated to the fiber longitudinal direction with respect to the row | line | column which consists of the said notch of the other layer. Moreover, in the prepreg base materials of both layers, the row of the cuts is a row distributed at equal intervals along the direction across the fiber, and the row of the cuts of one layer is the row of the other layer It is preferable that they are arranged so as to be shifted in the direction perpendicular to the fibers with respect to the row of cuts.

Here, the adjacent layers having substantially the same fiber direction are described with reference to FIG. 2. When the fiber direction is two directions as in (A) [0/90] _2S , layer a is used. And c layer, c layer and f layer, f layer and h layer, b layer and d layer, d layer and e layer, e layer and g layer, total 6 pairs, (B) [0 / ± 60] _{When the} fiber direction is 3 directions like _2S , a layer and d layer, d layer and i layer, i layer and l layer, b layer and e layer, e layer and h layer, h layer and k layer, c A total of nine sets of layers, the f layer, the f layer and the g layer, and the g layer and the j layer correspond to it. Although not shown in the figure, the same definition can be applied to a stacked structure such as [+ _45/0 / −45 / 90] _nS . The fiber direction is defined to be substantially the same direction in order to allow a slight angle deviation at the time of lamination, and the fact that the fiber direction is substantially the same usually means that the angle deviation is the same. , Within ± 10 °.

  When the prepreg base material of the present invention is laminated to obtain a fiber reinforced plastic, since the fiber is cut at the cut portion, the stress transmission is extremely reduced at that portion. Therefore, stress transmission is effectively performed by shifting the cutting positions of adjacent prepreg base materials having the same fiber direction.

  The length for shifting the cut is within a range of 0.1 L to 0.5 L in the longitudinal direction of the fiber or 0.1 W to 0.5 W in the direction perpendicular to the fiber with respect to the cut length W and the cut interval L. It is preferable to be within the range. A longer shifting length is preferable because stress transmission is improved, and the most effective form is when the distance L is shifted 0.5 times in the fiber longitudinal direction.

  The fiber-reinforced plastic of the present invention is preferably obtained by curing the laminated base material. Examples of the curing method, that is, the method of molding the fiber reinforced plastic include press molding, autoclave molding, sheet winding molding and the like. Of these, press molding is preferable in consideration of production efficiency.

  The fiber-reinforced plastic of the present invention has a planar skin portion and a protrusion on at least one side of the skin portion, and at least one of the layers constituting the stacked structure of the protrusion has the shape of the protrusion. It is preferred that the shape be along. That the laminated structure has a shape along the shape of the protrusion means that at least one of the layers constituting the laminated structure has a layer corresponding to each of the surfaces constituting the protrusion. In addition, when several SMC (sheet molding compound) or BMC (bulk molding compound) in which reinforcing fibers are randomly arranged are stacked and press-molded, finite length reinforcing fibers are independently oriented randomly on the side. Therefore, a clear layer is not formed in the thickness direction of the fiber reinforced plastic and is not included in the laminated structure referred to in the present invention.

  Here, unless otherwise specified, the skin portion represents a planar plate-like object such as a flat surface, a primary curved surface having a curvature of 1/100 or less, a secondary curved surface, or a spherical surface. Further, the protruding portion represents a portion such as a rib or a boss protruding from the skin portion. Further, in terms of fiber or a term including fiber (for example, “fiber direction”), the fiber represents a reinforcing fiber.

  As a method for forming the projecting portion, it is formed by pressing a laminated base material on which a prepreg base material is laminated in a double-sided die having a concave shape that forms a projecting portion on at least one mold. Although the mechanism by which the protrusions are formed by the above method is not clear, it is considered as follows. First, by pressing in a double-sided mold, the laminated substrate made of finite-length reinforcing fibers tends to flow in the in-plane direction while maintaining the laminated structure. And when the flow in the in-plane direction is saturated, if there is a concave space in the mold on one side, the laminated base material also flows in the concave space, that is, in the out-of-plane direction while maintaining the laminated structure. The protrusion is formed. In addition, since the fiber is not intentionally cut in the above process, the intermediate base material is made of a reinforced fiber having a finite length of 10 to 100 mm, like the fiber reinforced plastic.

The fiber-reinforced plastic of the present invention preferably has a laminated structure of at least two layers in which the orientation of the reinforcing fibers is different in the protrusion. Since there are a plurality of layers in which the orientation directions of the reinforcing fibers are different, the protrusions have excellent dimensional stability. When the orientation direction of the reinforcing fiber is only one direction, the protrusion is likely to warp due to the anisotropy of the linear expansion coefficient, and the dimensional accuracy may deteriorate. Further, in the rib among the protrusions, when a force in two directions is applied to the rib, or when a twisting force is applied, if the orientation direction of the reinforcing fibers is only one direction, There is a possibility that the strength and rigidity of the material will be insufficient. Therefore, it is necessary to have a laminated structure of at least two layers in which the orientation directions of the reinforcing fibers are different. Among them, the isotropic lamination such as [0/90] _nS , [0 / ± 60] _nS , and [+ _45/0 / −45 / 90] _nS , and the symmetrical lamination is that the fiber reinforced plastic itself has a sled. It is preferable in consideration of reduction or the like.

  In the fiber reinforced plastic of the present invention, the shape of the protrusions may be at least one selected from a plate shape, a rod shape, a hemispherical shape, a polygonal column shape, a columnar shape, a polygonal pyramid shape, a conical shape, and combinations thereof. preferable. For example, the rib is generally plate-shaped or rod-shaped, and the boss is generally hemispherical, polygonal columnar, cylindrical, polygonal pyramid, or conical.

  In the fiber reinforced plastic of the present invention, the height of the protrusion is preferably 0.5 to 50 times the thickness of the skin. 1 to 25 times is more preferable. If the height of the protrusion is within the above range, the effect as the protrusion is likely to be manifested. When the height of the protruding portion is smaller than 0.5 times the thickness of the skin portion, for example, if the protruding portion is a rib, the effect of improving the rigidity by the rib may be reduced. On the other hand, if the height is greater than 50 times, it may be difficult for the protrusions to form a layered structure.

  In the fiber reinforced plastic of the present invention, when the shape of the protrusion is plate-like or rod-like, the thickness of the protrusion is preferably 0.1 to 4 times the thickness of the skin part. 0.5-3 times is more preferable. If the thickness of the protrusion is within the above range, the effect as the protrusion is likely to be manifested. If the thickness of the protrusion is less than 0.1 times the thickness of the skin, for example, if the protrusion is a rib, the effect of improving the rigidity by the rib may be reduced, and if the protrusion is a boss, The dimensional accuracy of the mating part may not be achieved. On the other hand, when the thickness is larger than 4 times, it is difficult to obtain a material balance (material balance) between the skin portion and the protrusion portion, and it may be difficult for the skin portion and the protrusion portion to have a similar layer structure.

  The thickness of the prepreg substrate of the present invention is preferably in the range of 0.02 to 1 mm. When the thickness is less than 0.02 mm, the number of fibers cut by any one incision is inevitably reduced, and the fibers tend to swell due to flow during molding. Further, for example, in order to obtain a fiber reinforced plastic member having a thickness of 2 mm, it is necessary to laminate 100 or more prepregs, which is not preferable from the viewpoint of production efficiency. On the other hand, if it is thicker than 1 mm, the proportion of one layer when it is laminated increases, anisotropy appears remarkably, and the member may be warped.

  The carbon fiber that is the reinforcing fiber of the prepreg base material of the present invention is lightweight, has particularly excellent properties in specific strength and specific elastic modulus, and is also excellent in heat resistance and chemical resistance. Therefore, it is suitable for a member such as an automobile panel for which weight reduction is desired. Among these, PAN-based carbon fibers that can easily obtain high-strength carbon fibers are preferable.

  In order to obtain the prepreg base material of the present invention, as a method of cutting into the prepreg, first, a prepreg of continuous fibers aligned in one direction is prepared, and then the cutting is performed by a manual operation or a cutter using a cutter. There is a method, or a method of continuously incising through a rotating roller or the like in which a blade is arranged at a predetermined position in a prepreg manufacturing process of continuous fibers aligned in one direction. The former is suitable when the prepreg is simply cut, and the latter is suitable when producing a large amount in consideration of production efficiency. In addition, the prepreg base material of the present invention expresses the effect expected by making a cut only in the fiber cutting direction, but in the case where it is desired to remove the connection between fibers in the lateral direction, in addition to the longitudinal direction of the fiber You can make cuts.

Examples of the thermosetting resin used as the matrix resin for the prepreg base material of the present invention include epoxy resins, unsaturated polyester resins, vinyl ester resins, phenol resins, acrylic resins, and the like. There is no problem. The resin viscosity at normal temperature (25 ° C.) of these resins is preferably 1 × 10 ⁶ Pa · s or less, and if within this range, a prepreg base material having tackiness and draping properties satisfying the present invention is used. Obtainable.

  In such a matrix resin, the temperature T at which the thermosetting resin can be cured within 10 minutes is within the range of (Tp-60) to (Tp + 20), where Tp is an exothermic peak temperature due to DSC of the thermosetting resin. It is preferable that it exists in. Here, being able to cure means that the molding precursor containing the thermosetting resin can be taken out in a state in which the shape of the molding precursor is maintained after being held for a certain time at a certain temperature. As an evaluation method, 1.5 ml of a thermosetting resin was injected into a polytetrafluoroethylene O-ring having an inner diameter of 31.7 mm and a thickness of 3.3 mm placed on a heated press, and heated and pressurized for 10 minutes for crosslinking. This means that the resin test piece can be taken out without being deformed after the reaction has proceeded. When the temperature T at which the thermosetting resin can be cured within 10 minutes is lower than (Tp-60) ° C., there is a possibility that voids are generated inside the resin due to an abrupt reaction of the resin, resulting in poor curing. When the temperature is higher than Tp + 20) ° C., it takes time to raise the temperature at the time of molding. In addition, exothermic peak temperature Tp based on DSC in this invention is taken as the value measured on temperature rising conditions 10 degree-C / min conditions.

  Examples of the thermosetting resin exhibiting the above curing characteristics include compounds having at least an epoxy resin, a curing agent being an amine curing agent, and a curing accelerator having two or more urea bonds in one molecule. Specifically, 2,4-toluenebis (dimethylurea) or 4,4-methylenebis (phenyldimethylurea) is preferable as the curing accelerator.

  The prepreg base material of the present invention and fiber reinforced plastic using the same are used for members such as bicycle cranks and frames, shafts and heads of sports members such as golf, which require strength, rigidity and lightness. There are automotive parts such as doors and seat frames, and mechanical parts such as robot arms. Among them, in addition to strength and light weight, the shape of the member is complicated, and it can be preferably applied to a bicycle member such as a crank, an automobile part such as a seat panel or a seat frame, which requires shape followability like this material.

  Here, the prepreg base material of this invention is demonstrated using drawing. 3-7 is a top view which shows an example of the cutting pattern of the prepreg base material of this invention. FIG. 3 shows that the entire surface of the prepreg base material is provided with a plurality of rows of intermittent cuts in the direction crossing the fibers, and the adjacent rows are shifted in the direction perpendicular to the fibers, and adjacent to each other. The matching cuts in the row cut into each other. Furthermore, there are two rows of cuts, the cuts have the same shape, size, and direction, and the cut direction is the fiber orthogonal direction.

  FIG. 4 is the same as FIG. 3, but there are three rows of cuts. FIG. 5 is the same as FIG. 3, but the cutting direction is the fiber inclination direction. FIG. 6 is the same as FIG. 3 except for the shape and dimensions of the cuts. FIG. 7 is the same as FIG. 3 except that the cutting direction is different, and the cutting direction is the fiber tilt direction.

  On the other hand, FIG. 8 is a top view which shows an example of the cutting pattern of the prepreg base material which does not satisfy | fill this invention. As shown in FIG. 8, when the adjacent cuts are not cut from each other, there are continuous fibers 10 that are not cut by the cut.

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

<Flat plate forming method>
From the prepreg base material, it cut | disconnected to the magnitude | size of 250x250 mm in the direction shifted 45 degree | times from the fiber longitudinal direction and the fiber longitudinal direction, respectively. The cut prepreg base material is laminated in a 16-layer pseudo-isotropic ([45/0 / −45 / 90] _2S ), placed on a 300 × 300 mm mold, and then heated by a 6 MPa Curing was performed under the conditions of 150 ° C. × 30 minutes under pressure to obtain a plate-like molded body of 300 × 300 × 1.7 mm.

<Mechanical property evaluation method>
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 molded body. In accordance with the test method specified in JIS K-7073, the tensile strength was measured at a crosshead speed of 2.0 mm / min with a distance between the gauge points of 150 mm. In this example, an Instron (registered trademark) universal testing machine 4208 type was used as a testing machine. The number of test pieces measured was n = 10, and the average value was the tensile strength.
Further, a standard deviation was calculated from the measured value, and the standard deviation was divided by an average value, thereby calculating a variation coefficient (CV value (%)) as an index of variation.

Example 1
Epoxy resin ("Epicoat (registered trademark)" 828: 30 parts by weight, "Epicoat (registered trademark)" 1001: 35 parts by weight, "Epicoat (registered trademark)" 154: 35 parts by weight, manufactured by Japan Epoxy Resin Co., Ltd. Then, 5 parts by weight of a thermoplastic resin polyvinyl formal (“Vinylec (registered trademark)” K manufactured by Chisso Corporation) was heated and kneaded with a kneader to uniformly dissolve the polyvinyl formal, and then a curing agent dicyandiamide (Japan Epoxy Resin Co., Ltd.) ) DICY7) 3.5 parts by weight and 4 parts by weight of curing accelerator 3- (3,4-dichlorophenyl) -1,1-dimethylurea (Hodogaya Chemical Co., Ltd. DCMU99) were kneaded in a kneader. Thus, an uncured epoxy resin composition 1 was prepared. The epoxy resin composition 1 was applied onto a release paper having a thickness of 100 μm that had been subjected to silicone coating using a reverse roll coater to produce a resin film 1 having a thickness of 37 g / m ² . Next, the resin film 1 is overlapped on both sides of carbon fibers (tensile strength 4,900 MPa, tensile elastic modulus 235 GPa) arranged in one direction, and the resin is impregnated by heating and pressurizing, and the carbon fiber weight is 150 g / A prepreg 1 having m ² , a resin content of 33 wt% and a thickness of 0.15 mm was produced.

A prepreg base material having regular cuts at equal intervals was obtained by continuously inserting cuts as shown in FIG. 3 into the prepreg 1 using an automatic cutting machine. The incision direction is the fiber orthogonal direction, the incision length W is 10.5 mm, and the interval L (desired fiber length) is 30 mm. Adjacent cut rows are offset by 10 mm in the direction perpendicular to the fiber. That is, there are two patterns of the cut row. Furthermore, the cuts in adjacent rows are cut by 0.5 mm from each other. In addition, the number of fibers cut by any one incision is 23625. The viscosity of the epoxy resin in an atmosphere at 25 ° C. was 2 × 10 ⁴ Pa · s, and the substrate had tackiness.

Using the above prepreg base material, the size of 250 × 250 mm in each of the carbon fiber orientation direction (0 ° direction) and the direction shifted 45 degrees to the right from the carbon fiber orientation direction (45 ° direction) Cut out. In the adjacent layers where the orientation directions of the carbon fibers are the same in the cut prepreg base material, the row made of the cuts of the prepreg base material of one layer is the fiber with respect to the row made of the cuts of the prepreg base material of the other layer A laminated base material was obtained by stacking 16 layers in a pseudo isotropic manner so as to be displaced by 15 mm, which is 0.5 times the interval L in the direction ([−45 / 0 / + 45/90] _2S ).

  Furthermore, using the above-mentioned laminated base material, after placing it on a 300 × 300 mm flat plate mold, it was cured under conditions of 150 ° C. × 30 minutes under a pressure of 6 MPa by a heating press molding machine, A 300 × 300 mm flat fiber-reinforced plastic was obtained. The obtained fiber reinforced plastic was not even accompanied by fiber undulations, and the fibers were flowing evenly and sufficiently to the ends thereof. Moreover, there was no warp and it was favorable plane smoothness.

  The tensile strength was as high as 410 MPa, and the CV value was 4.5%, which was a small variation.

(Example 2)
Using the prepreg base material of Example 1, in the adjacent layers having the same fiber direction, the row composed of the prepreg base material cuts in one layer is the fiber relative to the row composed of the prepreg base material cuts in the other layer. Lamination is carried out so that the gap is 7.5 mm, which is 0.25 times the distance L in the direction, and 2.6 mm, which is 0.25 times the length W in the direction perpendicular to the fiber. Except for these points, a flat fiber-reinforced plastic was obtained in the same manner as in Example 1.

  The tensile strength was 390 MPa, which was slightly higher than that of Example 1, but the CV value was 5.0%, which was a small variation.

(Example 3)
The incision rows having the same shape and direction as in Example 1 are made into three patterns as shown in FIG. 4, the interval L (desired fiber length) is 30 mm, and the adjacent incision rows are shifted by 10 mm in the fiber orthogonal direction. It was. A prepreg base material was produced in the same manner as in Example 1 to obtain a flat fiber-reinforced plastic. The obtained fiber reinforced plastic was not even accompanied by fiber undulations, and the fibers were flowing evenly and sufficiently to the ends thereof. Moreover, there was no warp and it was favorable plane smoothness.

  The tensile strength was a high value of 400 MPa, and the CV value was 5.0%, which was a small variation.

Example 4
A prepreg base material was produced in the same manner as in Example 1 except that the length W of each cut was 12 mm, and a flat fiber-reinforced plastic was obtained. The adjacent row cuts are cut 2 mm from each other. Further, the number of fibers cut by any one cut is 27000. In the obtained fiber reinforced plastic, the fibers flowed evenly and sufficiently to the ends without causing the fibers to swell. Moreover, there was no warp and it was favorable plane smoothness.

  The tensile strength was 380 MPa, which was slightly inferior to that of Example 1, but a high value, and the CV value was 5.0%, which was a small variation.

(Example 5)
In the same manner as in Example 1, except that the curing accelerator was changed to 5 parts by weight of 2,4-toluenebis (dimethylurea) (“OMICURE (registered trademark)” 24) manufactured by PTI Japan Ltd. An uncured epoxy resin composition 2 was prepared, and a prepreg base material and a laminated base material using the prepreg base material were prepared in the same manner as in Example 1.

  A fiber-reinforced plastic was obtained in the same manner as in Example 1 except that only the pressing time (curing time) of the heating press molding machine was changed to 3 minutes. Despite the pressurization time being 1/10 that of Example 1, it was found that the glass transition temperature was almost the same, and the uncured epoxy resin composition 2 was excellent in fast curability.

  The tensile strength was as high as 420 MPa, and the CV value was 4.0%, which was a small variation. These values were comparable to those in Example 1.

(Example 6)
In the same manner as in Example 1, except that the curing accelerator was changed to 7 parts by weight of 4,4-methylenebis (phenyldimethylurea) (“OMICURE (registered trademark)” 52) manufactured by PTI Japan Ltd. An uncured epoxy resin composition 3 was prepared, and a prepreg base material and a laminated base material using the prepreg base material were prepared in the same manner as in Example 1.

A fiber-reinforced plastic was obtained in the same manner as in Example 1 except that only the pressing time (curing time) of the heating press molding machine was changed to 3 minutes. Despite the pressurization time being 1/10 that of Example 1, it was found that the glass transition temperature was almost the same, and the uncured epoxy resin composition 2 was excellent in fast curability.
The tensile strength was as high as 415 MPa, and the CV value was 4.0%, which was a small variation. These values were comparable to those in Example 1.

(Comparative Example 1)
A flat fiber reinforced plastic was obtained in the same manner as in Example 1 except that the prepreg was not cut. The fiber reinforced plastic had a shape of 300 × 300 × 1.7 mm, but its end was formed of resin, and the fiber stayed at the position before pressing and hardly flowed. Further, warping was caused by the difference in linear expansion coefficient between the excessive fiber portion at the center and the excessive resin portion at the end of the molded body.

  Since the fibers were not cut, the tensile strength was very high at 700 MPa and the CV value was 4.5%, which was a small variation, but the fluidity was extremely poor as described above.

(Comparative Example 2)
A prepreg base material was produced in the same manner as in Example 1 except that the length W of the cut was 10 mm and the notches in the adjacent rows were not cut into each other to obtain a flat fiber-reinforced plastic. There were some fibers longer than 30 mm that were not cut by the incision, and the flow of the fibers was disturbed in this portion, and the fibers did not flow to the end of the fiber reinforced plastic. Furthermore, since the flow state was not uniform, warping was caused by the difference in linear expansion coefficient.

  The tensile strength was 360 MPa, a value lower than that of Example 1. Since the flow state was not uniform, the CV value was as high as 10.0%, that is, the variation was large.

(Comparative Example 3)
In an adjacent layer where the distance L (desired fiber length) is 6 mm and the fiber direction is the same, a row made of the prepreg base material cuts of one layer is a row made of the prepreg base material cuts of the other layer A prepreg base material was produced in the same manner as in Example 1 except that lamination was carried out so that the distance L was shifted by 3 mm, which was 0.5 times the distance L in the fiber direction, to obtain a flat fiber-reinforced plastic. The obtained fiber reinforced plastic was not even accompanied by fiber undulations, and the fibers were flowing evenly and sufficiently to the ends thereof. Moreover, there was no warp and it was favorable plane smoothness.

  However, since the fiber length was short, the reinforcing effect by the fiber was lowered, and the tensile strength was a very low value of 250 MPa. The CV value was 5.0%, which was a small variation.

(Comparative Example 4)
A prepreg base material in which the notch length W is 10 mm and the notches in the adjacent rows are not cut into each other is prepared, and in an adjacent layer having the same fiber direction, a row of prepreg base material notches in one layer is Example 1 except that the other layer was formed so as to overlap the fiber direction and the fiber orthogonal direction with respect to the row of the prepreg substrate cuts of the other layer, and to obtain a laminated substrate. In the same manner, a flat fiber-reinforced plastic was obtained. There were some fibers longer than 30 mm that were not cut by the incision, and the flow of the fibers was disturbed in this portion, and the fibers did not flow to the end of the fiber reinforced plastic. Furthermore, since the flow state was not uniform, warping was caused by the difference in linear expansion coefficient.

  The tensile strength was 180 MPa, which was a very low value compared to Example 1. Since the flow state was not uniform, the CV value was as high as 11.5%, that is, the variation was large.

(Comparative Example 5)
A prepreg base material was produced in the same manner as in Example 1 except that the matrix resin was nylon 6 resin and the release paper was not used. The viscosity of the nylon 6 resin in an atmosphere at 25 ° C. was a solid and could not be measured, and the substrate had no tackiness. Furthermore, the base material was separated into small pieces, and the form as a sheet could not be maintained, and it was impossible to form and of course to laminate.

It is an enlarged plan view which shows an example of the cutting pattern of the prepreg base material of this invention. It is a schematic diagram of a lamination | stacking cross section. It is a top view which shows an example of the cutting pattern of the prepreg base material of this invention. It is a top view which shows another example of the cutting pattern of the prepreg base material of this invention. It is a top view which shows another example of the cutting pattern of the prepreg base material of this invention. It is a top view which shows another example of the cutting pattern of the prepreg base material of this invention. It is a top view which shows another example of the cutting pattern of the prepreg base material of this invention. It is a top view which shows an example of the cutting pattern of the prepreg base material which does not satisfy | fill this invention.

Explanation of symbols

1: Fiber longitudinal direction 2: Fiber orthogonal direction 3: Pre-preg base material 4: Notch 5: Width cut into each other 6: Desired fiber length 7: Row made of the first cut 8: Row made of the second cut 9 : Row 10 consisting of third cuts: Continuous fiber not cut by the cuts

Claims (18)

A prepreg base material composed of carbon fibers and thermosetting resin aligned in one direction and in close contact with a tape-like support, and intermittently extending in the direction across the fiber across the entire surface of the prepreg base material. A plurality of rows of incisions having a length W of ˜50 mm are provided, and the interval L between the rows and the first overlapping row when the rows are translated in the fiber longitudinal direction is 10 to 100 mm, The prepreg base material, wherein the adjacent rows are shifted in the direction perpendicular to the fibers, and the cuts of the adjacent rows are cut into each other. 2. The prepreg base material according to claim 1, wherein the adjacent cuts of the row have a width of 0.1 mm or more and 0.1 times or less of the shorter one of the adjacent cuts. The prepreg base material according to claim 1 or 2, wherein the cuts have the same shape, size, and direction. The prepreg base material according to any one of claims 1 to 3, wherein the cuts are continuously distributed at equal intervals along a direction crossing the fiber. The prepreg base material according to any one of claims 1 to 4, wherein all the cutting directions are fiber orthogonal directions. The prepreg base material according to any one of claims 1 to 5, wherein the number of fibers cut by any one incision is 5000 to 50000. The temperature T at which the thermosetting resin can be cured within 10 minutes is in the range of (Tp-60) to (Tp + 20), where Tp is an exothermic peak temperature due to DSC of the thermosetting resin. The prepreg base material in any one of 1-6. The prepreg group according to any one of claims 1 to 7, wherein the thermosetting resin is an epoxy resin containing an amine-based curing agent as a curing agent and a compound having two or more urea bonds in one molecule as a curing accelerator. Wood. The prepreg base material according to any one of claims 1 to 8, wherein the curing accelerator is 2,4-toluenebis (dimethylurea) and / or 4,4-methylenebis (phenyldimethylurea). A laminated base material obtained by laminating and integrating the prepreg base material according to claim 1. In adjacent layers in which the fiber directions are substantially the same direction, rows of intermittent cuts of the length W of both layers of the prepreg base are equally spaced, and the cuts of the prepreg base of one layer The laminated base material according to claim 10, wherein the row made of is displaced in the fiber longitudinal direction with respect to the row made of the notches of the prepreg base material of the other layer. The laminated base material according to claim 11, wherein the rows formed by cutting the prepreg base materials of each layer are arranged so as to be shifted in the fiber longitudinal direction within a range of 0.1 to 0.5 times the distance L. In adjacent layers in which the fiber direction is substantially the same direction, the prepreg base material of both layers is a row distributed at equal intervals along the direction across the fiber, and the prepreg base material of one layer The laminated substrate according to claim 10 or 11, wherein the row of cuts is arranged in a fiber orthogonal direction with respect to the row of cuts of the prepreg substrate of the other layer. The laminated base material according to claim 13, wherein the rows of cuts of the prepreg base material of each layer are arranged so as to be shifted in the fiber orthogonal direction within a range of 0.1 to 0.5 times the length W. A fiber reinforced plastic obtained by curing the laminated base material according to claim 10. It has a planar skin part and a protrusion on at least one surface of the skin part, and at least one of the layers constituting the laminated structure of the protrusion has a shape along the shape of the protrusion. The fiber-reinforced plastic according to claim 15. The fiber according to claim 15 or 16, wherein the shape of the protrusion is at least one selected from a plate shape, a rod shape, a hemispherical shape, a polygonal column shape, a columnar shape, a polygonal pyramid shape, a conical shape, and combinations thereof. Reinforced plastic. The fiber-reinforced plastic according to any one of claims 15 to 17, wherein the height of the protruding portion is 0.5 to 50 times the thickness of the skin portion.

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