JP4779754B2 - Prepreg laminate and fiber reinforced plastic - Google Patents

Description

  The present invention relates to a prepreg laminate which is an intermediate substrate of fiber reinforced plastic suitably used for, for example, automobile members, sports equipment, and the like, and a fiber reinforced plastic obtained by heating and curing the prepreg laminate. Specifically, a prepreg base material that has good fluidity and molding followability during molding and can exhibit excellent mechanical properties, low variation and excellent dimensional stability when molded into fiber reinforced plastic. The present invention relates to a laminate and a fiber reinforced plastic.

  Fiber reinforced plastics, in which reinforced fibers are impregnated with matrix resin and cured, have high specific strength, high specific modulus, excellent mechanical properties, and high functional properties such as weather resistance and chemical resistance. The application is attracting attention and its demand is increasing year by year.

  As a method of molding such fiber reinforced plastic, a semi-cured intermediate base material (prepreg) obtained by impregnating continuous reinforcing fibers with a matrix resin is laminated in a mold, and the whole is vacuum-packed, Autoclave molding and oven molding methods are generally used in which the matrix resin in the mold is cured by heating and pressing in an oven. Also, in recent years, for the purpose of improving production efficiency, RTM (resin transfer molding) molding in which a matrix resin is injected into a continuous reinforcing fiber base that has not been impregnated with a resin that has been shaped in advance into the shape of a molded member and then cured after impregnation. Laws are also in place.

  The fiber reinforced plastics obtained by these molding methods have excellent mechanical properties because the reinforced fibers are continuous fibers. In addition, since the continuous fibers are regularly arranged, it is possible to design the required mechanical properties by arranging the base material, and there is an advantage that the variation in the mechanical properties is small.

  However, on the other hand, since all of the reinforcing fibers constituting the prepreg base material are continuous fibers, the reinforcing fibers are strong and it is difficult to form a molded body having a complicated uneven shape such as a three-dimensional shape. For this reason, at present, the application is limited to members mainly having a planar shape. In particular, in the case of a prepreg, the reinforcing fiber is impregnated with a resin in advance, so that the rigidity is increased and it is further difficult.

  From such a point, there is an SMC (sheet molding compound) molding method as a molding method suitable for a complicated shape such as a three-dimensional shape. In the SMC molding method, an SMC sheet which is semi-cured by impregnating a chopped strand, which is usually cut to about 12 to 25 mm, with a matrix resin of a thermosetting resin, is heated using a heating type press machine (hot press machine). -Molding is performed by applying pressure. In many cases, the SMC sheet is arranged on the mold as an aggregate smaller than the shape of the molded body before pressing, and the SMC sheet is flowed to 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 fluidity.

  However, SMC is inevitably caused by uneven distribution of chopped strands and uneven alignment in the sheet forming process, resulting in a decrease in mechanical properties of the obtained molded product or a large variation in its value. There is a drawback. Furthermore, the uneven distribution of the chopped strands and the uneven alignment tend to cause warpage, sink marks, etc., particularly in a thin material, which is often unsuitable as a structural material.

  In order to fill in the drawbacks of the above-described materials, a base material that can be made fluid and small in variation in mechanical properties by cutting into a prepreg composed of continuous reinforcing fibers and a thermoplastic resin is disclosed (for example, Patent Document 1).

However, in the technique of Patent Document 1, since a thermoplastic resin is used as a matrix resin, there is a problem in that the base material is slipped during lamination and the drape property due to the absence of tackiness (adhesiveness). There is a problem that it is difficult to shape a member having an uneven part because it is not deformable or because it is a thermoplastic resin and has a high viscosity and is difficult to flow. In addition, since the thermoplastic resin does not have tackiness, it cannot be held as a laminate by laminating prepreg base materials, and therefore, there is also a problem that it is difficult to mold as designed because shape cannot be maintained after shaping. . Furthermore, in terms of mechanical properties, there is a problem in that all the reinforcing fibers are cut as compared with the above-described reinforcing fiber plastics reinforced with continuous fibers.
Japanese Patent Publication No. 8-5079 (Claims 1, 2 and 1)

  The present invention eliminates the problems of the prior art, has good fluidity and followability to complex shapes, and has excellent mechanical properties and low variation and excellent dimensions when used as a fiber reinforced plastic. An object of the present invention is to provide a prepreg laminate and a fiber-reinforced plastic that can exhibit stability.

The present invention employs the following means in order to solve such problems. That is,
(1) In a prepreg laminate in which a plurality of layers of sheet-like prepregs obtained by impregnating a matrix resin into reinforcing fibers arranged in one direction and arranged in a plane,
(A) The sheet-shaped prepreg is made of continuous carbon fibers as reinforcing fibers, and the matrix resin as a thermosetting resin .
( B) The sheet-like prepreg includes a prepreg base material laminate obtained by laminating a plurality of prepreg base materials into which cuts of a finite length are intermittently cut in a direction crossing the fiber direction of the continuous carbon fibers, and the incision. And a continuous carbon fiber without reinforcing, and a prepreg substrate disposed on at least one side of the outermost layer of the prepreg substrate laminate ,
(C) All prepreg base materials constituting the prepreg base material laminate are in the direction in which the fibers cross the entire surface of the prepreg base material, and incision rows of 2 to 50 mm (L) are fiber directions of the reinforcing fibers. Are provided in a plurality of rows with a distance (L2) of 10 to 100 mm, the adjacent rows of the plurality of rows are shifted in the fiber orthogonal direction, and the cuts of the adjacent rows are the overlap width of the cuts A prepreg laminate characterized by being cut into each other at (L1) .
(2) The continuous carbon fiber of the prepreg base material disposed on at least one side of the outermost layer of the laminate is a carbon fiber that is aligned in only one direction. Prepreg laminate.
(3) Item (1), wherein the prepreg substrate disposed on at least one side of the outermost layer of the laminate includes a woven fabric woven with continuous carbon fibers aligned in two directions. The prepreg laminate according to 1.
(4) The overlap width (L1) of the cuts that are cut into each other is 0.1 mm or more and 0.1 or less times the length of the shorter cut among the cuts in adjacent rows. The prepreg laminate according to any one of (1) to (3) , which is characterized.
(5) The prepreg laminate according to any one of (1) to (4) , wherein any one of the shapes, dimensions, and directions of the notches in the adjacent rows is the same.
(6) The prepreg laminate according to any one of (1) to (5) , wherein the cuts are provided at equal intervals in a direction crossing a fiber direction of the reinforcing fibers.
(7) The prepreg laminate according to any one of (1) to (6 ), wherein the crossing direction of the cuts is a direction orthogonal to the fiber direction of the carbon fiber.
(8) The prepreg laminate according to any one of (1) to (7) , wherein the number of fibers cut by any one incision is in the range of 5,000 to 50,000.
(9) The prepreg according to any one of (1) to (8) , wherein at least the prepreg base material having the continuous carbon fiber as a reinforcing fiber is shaped into a product shape in advance. Laminated body.
(10) A fiber-reinforced plastic obtained by heating and curing the prepreg laminate according to any one of (1) to (9) .

  According to the present invention, it is possible to obtain a prepreg laminate having good fluidity at the time of molding and followability to complicated shapes, and when the laminate is heated and molded, excellent mechanical properties and low It is possible to obtain a fiber reinforced plastic capable of exhibiting variation and excellent dimensional stability.

  The fiber reinforced plastic obtained by heating and molding the prepreg base material having a notch in the direction perpendicular to the fiber direction of the continuous reinforcing fibers is a matrix resin as a thermosetting resin. Compared to SMC molded products using short fibers with a fiber length of about 12 to 25 mm as reinforced fibers, they exhibit much higher mechanical properties such as tensile strength and tensile elastic modulus, but still only continuous fibers with no cuts. Compared to fiber reinforced plastics, which are reinforced prepreg base materials that have been thermoformed, we have intensively studied to improve the problem of low tensile strength, bending strength and bending elastic modulus. By placing a prepreg reinforced with continuous fibers only on the surface layer part where the load is greatest when an external force is applied, It is obtained by investigation to be able to solve serial problems to one fell swoop.

  Hereinafter, the best mode for carrying out the present invention will be specifically described with reference to the drawings. Note that the drawings are only examples of the present invention, and the present invention is not limited thereto.

  First, the overall configuration of the prepreg laminate according to the present invention will be described.

  FIG. 1 is an overall view of a prepreg laminate 1 according to the present invention. Among these, FIG. 1A is a partially broken view of each prepreg substrate 2, 3 other than the prepreg substrate 4 in the lowermost layer in order to show a laminated configuration. FIG. 1B is a cross-sectional view taken along the line AA in FIG. 2-7 is a partial top view which shows the example of various patterns in each prepreg base material in the prepreg laminated base material 2 of FIG.

  In FIG. 1, the prepreg laminated body 1 of this invention is comprised roughly by the prepreg laminated base material 2 and the prepreg base materials 3 and 4 arrange | positioned on the front and back.

  The prepreg laminated substrate 2 is formed by laminating prepreg substrates 2a to 2d each having a notch 6 with a direction or a predetermined angle perpendicular to the fiber direction with respect to the reinforcing fibers of the prepreg substrate (see reference numeral 7 in FIG. 2). Thus, when the final product is a fiber reinforced plastic, the fluidity of the reinforcing fiber and the effect of following the uneven surface of the mold are exhibited. Further, the prepreg base materials 3 and 4 are composed of continuous fibers having no cuts in the reinforcing fibers in order to compensate for the tensile strength, bending strength, and bending elastic modulus, which are weak points of the prepreg having cuts on the surface. is there. In the figure, the prepreg base materials 3 and 4 are base materials in the form of a woven fabric composed of warp yarns and weft yarns of continuous fibers.

  As the reinforcing fibers constituting these prepreg base materials 2a to 2d, 3, and 4, carbon fibers having particularly excellent properties in terms of specific strength and specific elastic modulus are used in the present invention. Examples of the carbon fiber include two types of PAN-based and pitch-based carbon fibers, and PAN-based carbon fibers from which high-strength carbon fibers can be easily obtained are preferable. In addition to the above properties, the carbon fiber is light in weight, and is preferable in that it has excellent heat resistance and chemical resistance.

As the matrix resin, a thermosetting resin is used in place of the thermoplastic resin which has been one of the causes of the problems of the prior art in the present invention. Examples of the thermoplastic resin include an epoxy resin, an unsaturated polyester resin, a vinyl ester resin, and a phenol resin, and a mixed resin thereof may be used. 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 substrate having tackiness and draping properties satisfying the present invention is obtained. be able to.

  The thickness of one layer of each of the prepreg base materials 2a to 2d, 3 and 4 is preferably in the range of 0.02 to 1 mm although it depends on the thickness of the molded product. When the thickness is smaller than 0.02 mm, the number of fibers cut by any one notch is inevitably reduced, and the fibers are liable to flow excessively during molding, and the fibers are liable to be deformed such as waviness. For example, in order to obtain a fiber reinforced plastic member having a molded product thickness of 2 mm, it is necessary to laminate 100 or more prepreg base materials, which is not realistic from the viewpoint of production efficiency. On the other hand, when the thickness of one layer of the prepreg base material is thicker than 1 mm, the fiber occupancy (distribution rate) that one layer takes up when laminated is increased, so that anisotropy appears remarkably, and the molded member has a warp or the like. May occur.

  Next, the prepreg laminated substrate 2 which is a constituent substrate of the prepreg laminated body 1 of the present invention will be described in detail.

  FIG. 2 is a partially enlarged plan view of the prepreg base material 2b of the prepreg laminated base material 2 of FIG. 1, and the Y-axis direction in the figure is the fiber axis direction of the reinforcing fibers 7 (hereinafter simply referred to as the fiber direction). The X-axis direction indicates a direction orthogonal to the fiber direction.

  As shown in FIG. 2, the prepreg base material 2b is impregnated with a thermosetting resin (not shown) as a matrix resin in a carbon fiber aligned in one direction in the Y direction of the figure as the reinforcing fiber 7. The prepreg 5 is in close contact with and supported by a release paper (not shown) in a state in which a plurality of cuts 6a and 6b are inserted in the X direction orthogonal to the fiber direction, and is protected from dust adhesion and the like. .

  As described above, the prepreg base material is closely attached and supported by the release paper, so that it is possible to maintain the form even when all the reinforcing fibers 7 are cut by the notches 6, and the fibers are individually conveyed at the time of conveyance. There is no problem of separating and falling apart. This adhesion / support is possible only when the matrix resin is a thermosetting resin having tackiness, and in the case of a prepreg base material composed of a thermoplastic resin of the prior art that does not have tackiness, release paper is used. Therefore, it is difficult to convey and laminate the prepreg base material. In the present invention, the “release paper” is a sheet formed of paper such as kraft paper, polymer films such as polyethylene / polypropylene, metal foil such as aluminum, etc., and is separated from the resin. In order to obtain moldability, a silicone-based or “Teflon (registered trademark)” release agent, metal vapor deposition, or the like may be applied to the support surface.

  The cuts 6a and 6b are both provided in a row in an intermittent manner in the X direction across the reinforcing fiber 7. For example, the notches 6a have a finite length with a notch length L in the range of 2 to 50 mm, and a plurality of notches 6a are provided in a line through a non-notched interval L3 up to the next notch 6a. When the cut length L is less than 2 mm, the aggregate of the fibers is small, so that the fibers are likely to be deformed due to flow during molding, resulting in a decrease in mechanical properties. Since the aggregate of a group of fibers becomes large, the fluidity of the fibers deteriorates and the variation in mechanical properties increases. In this respect, the cut length L is more preferably 5 to 30 mm.

  In addition, on both sides of the notch 6a, the notches 6b are intermittently provided in a row at a position across the non-notched interval L3 of the notch 6a. That is, the notch 6b is provided in a positional relationship in the range of 10 to 100 mm as the fiber length, with a distance L2 from the notch 6b row that first overlaps when the row is translated in the fiber longitudinal direction.

  Further, the notch 6b is displaced in the fiber orthogonal direction to the position where the notch 6b straddles the notch 6a as compared with the notch 6a, and the relative position in the X direction with the notch 6a in the adjacent row is longer by the notch 6a. The length L1 is cut and the cuts overlap each other. On the other hand, the same is true when viewed from the side of the notch 6a, and the length 6 is cut by the notch 6b. In the present invention, it is an essential requirement that the cut overlap exists, and the cut overlap width L1 is 0.1 mm or more.

  When L1 is smaller than 0.1 mm, it is practically difficult to control mechanical cutting, and a fiber longer than the desired fiber length may be generated without being cut by the cutting operation, which is preferable because the fiber significantly impedes fluidity. Absent.

Further, as shown in FIG. 6, the respective cut rows having the cuts 6 a and 6 b do not necessarily have the same cut length L, and may have different cut lengths (La and Lb, La> Lb). . In this case, it is also an essential condition that the length is not more than 0.1 times the shorter length (Lb) of the adjacent cuts (6a, 6b). (Thus, the overlap width L1 of the cuts in this case is L1 ≦ 0.1 × Lb.)
On the other hand, when the overlap width L1 of the cuts is larger than 0.1 times the shorter one of the adjacent cuts (Lb), the ratio of the number of fibers cut into each other relative to the number of fibers cut by any one cut, ie, The ratio of fibers (L4, L5) shorter than the desired fiber length L2 is increased, and the mechanical properties of the fiber-reinforced plastic after molding are significantly reduced. The “shorter of 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 end is not hooked. Judgment is based on the inner notch. In addition, when each adjacent row is not shifted by the length L3 in the X direction, there are fibers that are not cut by the cutting, so that the fluidity of the reinforcing fibers at the time of filling the molding die with the matrix resin is remarkably lowered.

  Further, since the above-mentioned “interval L2” is a cutting length with respect to the reinforcing fiber 7, it is a value that greatly affects the mechanical properties of the fiber-reinforced plastic to be molded. I will call it. As described above, the distance L2 is preferably in the range of 10 to 100 mm. However, if the distance L2 is smaller than 10 mm, the length of the fiber is also shortened, so that the reinforcing effect by the fiber is reduced, and sufficient mechanical properties are obtained when a fiber reinforced plastic is obtained. Can't get. On the other hand, when it is larger than 100 mm, the fluidity at the time of molding deteriorates and it is difficult to form a complicated shape. Therefore, the more preferable interval is 10 to 50 mm. In the case of FIG. 2, the width of the strip-shaped prepreg having the desired fiber length L2 is L3, and the relationship between the length Lb of the notch 6b itself and the notch overlap width L1 is Lb = L3 + 2L1. . And it is preferable that the fiber number cut | disconnected by arbitrary 1 cut | disconnect is the range of 5,000-50,000. When the number of fibers is less than 5,000, the fibers are likely to be deformed such as waviness due to the flow during molding, and the mechanical properties may be deteriorated. When the number of fibers is more than 50,000, the aggregate of the fibers surrounded by the notch spacing adjacent to each other in the longitudinal direction of the fiber becomes large, so that the fluidity of the fiber is deteriorated and only the mechanical properties are lowered. In addition, the variation becomes large, which is not preferable.

  Although the basic structure of the cutting is as described above, when applied to the prepreg base materials 2a to 2d, the following various forms can be adopted.

  That is, as the cutting direction applied to each of the prepreg base materials 2a to 2d, the cutting direction can be inclined with respect to the fiber direction as shown in FIGS. It is preferable. When the cutting directions are all in the direction perpendicular 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.

  Moreover, it is preferable that the shape, size, and direction of the cut are the same. Although the effect of the present invention can be obtained even if the shape, size, and direction of the cut are two or more, the fluidity of the fibers is uniform rather than anisotropic because all of them are the same. This is because the occurrence of warpage is suppressed, the occurrence of warpage is suppressed, and the design of a molded article having arbitrary mechanical properties is facilitated by controlling the orientation in the fiber direction.

  Moreover, it is preferable that each prepreg base material 2a-2d is continuously distributed at equal intervals along the direction in which the cuts cross the fibers. In the case of equal intervals, the flow of the fibers becomes uniform as in the shape, size and direction of the above-mentioned cuts, so that the fluidity of the fibers can be easily controlled, the occurrence of warpage is suppressed, and the orientation control in the fiber direction is performed. Therefore, it is preferable because the structure design of a molded body having an arbitrary mechanical property is facilitated.

  Moreover, as a pattern of the prepreg base materials 2a-2d which comprise the prepreg laminated base material 2, it is preferable to include the 2-6 patterns of several things. That is, if the reinforcing fiber has not only the 0/90 ° direction but also a pattern having a skew direction of ± 45 ° within this range, the prepreg base material having another pattern has the disadvantage that there is only one pattern. It complements each other and can exhibit more isotropic properties in the fluidity of the reinforcing fibers. However, when there is only one pattern of the constituent prepreg base material, there are fibers that are not cut by cutting, and the fluidity of the fibers is significantly reduced. On the other hand, when there are 7 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.

  3 to 7 are plan views showing a notch pattern different from the notches 6a and 6b in FIG. 2, and FIG. 3 shows a notch comprising a first notch row 9 and a second notch row 10. FIG. The two patterns have the same shape, size and direction of the cut. FIG. 4 shows three patterns in which the cut rows are composed of three rows 9 to 11, FIG. 5 shows the pattern rows 9 and 10 in FIG. 3 inclined by 45 °, and FIG. 6 shows the cut rows 9 and 10 in FIG. 7 in which the length of the cut row 10 is shortened, FIG. 7 is a view in which the pattern rows 9 and 10 of FIG.

  Thus, the cutting pattern can be various patterns depending on the mold, the structure of the fiber reinforced plastic to be molded, and the flow direction of the reinforcing fibers. That is, in the present invention, the adjacent rows of the prepreg laminated base material are cut into each other to form a desired fiber length and a reinforcing fiber shorter than the desired fiber length, and the fluidity of the fiber is very good. It becomes. On the other hand, when the cuts in the adjacent rows are not cut from each other, fibers longer than the desired fiber length are generated without being cut by the cuts, and the fibers remarkably 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 the occurrence of deformation such as swell and twist. Therefore, the adjacent rows of cuts of the prepreg base material having the cuts cut each other, that is, by having the portions where the cuts overlap, it is possible to reliably prevent generation of reinforcing fibers longer than the desired fiber length. In the laminated base material 2, all the reinforcing fibers are not continuous fibers but are composed of at least two kinds of reinforcing fibers of short fibers having different lengths. In the present invention, the “short fiber” has a length of 100 mm or less. By inserting notches that satisfy the above conditions into the entire surface of the prepreg base material having notches, the reinforcing fibers can flow during molding, particularly in the longitudinal direction of the fibers. Excellent formability. When there is no notch, that is, when all the reinforcing fibers are continuous fibers only, they do not flow in the longitudinal direction of the fibers, so that a complicated shape cannot be formed and can be applied only to a considerably limited shape. As shown in FIG. 1, the prepreg laminated substrate 2 is formed by sequentially laminating and integrating the above-described prepreg substrates 2a to 2d. However, as the laminated configuration, a laminated configuration suitable for each application is used. Although there is no particular limitation, pseudo-isotropic lamination such that the fiber orientation of the laminate is [0 / ± 45/90] s, [60/0 / -60] or the like is obtained, and the resulting molded product is evenly distributed. It has excellent physical properties and has a great effect of suppressing the occurrence of warpage. Furthermore, by laminating and integrating, the handleability at the time of molding is improved, and further, the molding can be performed while maintaining the laminated structure as designed. Moreover, 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 with each other by adhesion, and has a synergistic effect.

  Next, the prepreg base materials 3 and 4 that are constituent base materials of the prepreg laminate 1 of the present invention will be described.

  As described above, the prepreg base materials 3 and 4 are provided in order to improve the deterioration of the mechanical properties due to the short fiber structure, which is a drawback of the prepreg laminated base material 2. That is, in the case of a prepreg laminated base material composed of a prepreg base material having only continuous fibers without cuts 6a and 6b as reinforcing fibers, as described above, the shape followability, that is, the formability is poor, and the molded shape is reduced. In the present invention, as shown in FIG. 1, the central portion in the thickness direction is constituted by a prepreg product base material 2 with a cut, and when the bending load is applied, the surface layer having the largest load is present. Place a continuous fiber reinforced prepreg with no breaks only in the part. The continuous fiber reinforced prepregs 3 and 4 are not necessarily arranged on both surfaces of the prepreg laminated base material 2, and depending on the application and load conditions, the arrangement can be greatly improved.

Further, the number of laminated continuous fiber reinforced prepregs 3 and 4 varies depending on the conditions of the prepreg base material (fiber type, basis weight, etc.) and molding shape. For example, when the basis weight is 200 g / m ² or more, 8 layers or less, preferably 4 layers or less are suitable. In addition, as a fabric weight, the thing of the range of 150-450 g / m < ² > is preferable. Is less than 150 g / m ^2, may decrease the reinforcing effect for a small amount of reinforcing fibers, the fibers tend to cause turbulence of the fiber since it tends to flow excessively, stiffness exceeds 450 g / m ² substrate is high This is because it is difficult to follow complicated shapes.

  Furthermore, examples of the prepreg base materials 3 and 4 include woven fabrics having a woven structure such as plain weave, twill weave and satin weave, and unidirectional base materials. In addition, the mat-like base material in which the fiber is bent is not suitable.

  The prepreg laminate of the present invention is as described above, but has the following excellent actions and effects.

The prepreg laminated base material 2 constituting the prepreg laminated body 1 includes prepreg base materials 2a to 2d having various patterns in which the direction of the reinforcing fiber 7 is one direction and the fiber orientation angle is changed. The orientation control in the fiber direction becomes easy, and the structural design of a fiber-reinforced plastic molded article having arbitrary mechanical characteristics becomes possible. The carbon fiber of the reinforcing fiber is lightweight, yet has particularly excellent properties in specific strength and specific elastic modulus, and is also excellent in heat resistance and chemical resistance. It is suitable for various members such as bicycle / motorcycle parts and windmills.
Moreover, since the matrix resin is a thermosetting resin, the prepreg base material has tackiness at room temperature. Therefore, when the base material is laminated, it is easy to be integrated with the adjacent base material by adhesion, and it can be molded while maintaining the intended laminated structure. That is, since a prepreg base material composed of a thermosetting resin has excellent drapeability at room temperature, for example, when molding using a mold having a concavo-convex part, pre-shaped along the concavo-convex part in advance. It can be done easily. By this pre-shaping, the moldability is remarkably improved, and the flow control for the reinforcing fibers and the matrix resin along the unevenness of the mold becomes easy. On the other hand, in the case of a prepreg base material using a conventional thermoplastic resin having no tack property at room temperature as a matrix resin, it is difficult to laminate the prepreg base material at room temperature. Can be difficult to handle, resulting in a fiber-reinforced plastic with large fiber orientation unevenness. In particular, the difference appears remarkably when molding with a mold having an uneven portion.

  The prepreg laminate and fiber reinforced plastic according to the present invention described above can be produced, for example, as follows.

  First, a prepreg base material using carbon fibers aligned in one direction as reinforcing fibers and a thermosetting resin as a matrix resin is prepared by a known method and supported by the aforementioned release paper.

  Next, cuts 6a and 6b in various directions are made on the surface of the prepreg base material to create individual base materials of the prepreg base materials 2a to 2d in FIG. As a method of cutting into the prepreg base material, a method of cutting with a manual operation using a cutter or an automatic cutting machine, or a desired fiber length interval in a prepreg manufacturing process of continuous fibers aligned in one direction. There is a method of continuously cutting through a rotating roller or the like in which a cutting blade is arranged at a distance. The former is suitable when the prepreg base material is simply cut, and the latter is suitable when producing a large amount in consideration of production efficiency. In addition, as the prepreg laminated base material 2, the effect expected by cutting only in the direction of cutting the reinforcing fibers is expressed, but in the case where it is desired to remove the connection between the fibers in the lateral direction, You can make a cut in the direction. And the obtained prepreg base materials 2a-2d are laminated | stacked in this order, and the prepreg laminated base material 2 of FIG. 1 is obtained.

  Next, a prepreg base material 3 or 4 is prepared by using a woven fabric made of continuous carbon fibers of warp and weft yarns, and a thermosetting resin as a matrix resin, and the outermost surface of the prepreg laminated base material 2 described above. The prepreg laminate 1 of the present invention is laminated on both sides.

  The obtained prepreg laminate 1 is further laminated according to the installation location according to the uneven shape in the mold, and the entire prepreg laminate 1 is heated and cured at a predetermined temperature for a predetermined time together with the mold, and is removed from the mold. It becomes the fiber-reinforced plastic of the invention. Examples of the heat-curing method include vacuum bag molding, mold press molding, autoclave pressure molding, sheet winding molding, and the like, and mold press molding, that is, hot press molding is preferable in consideration of production efficiency.

  The prepreg laminate of the present invention and the fiber reinforced plastic formed from the laminate can be used suitably for all industrial applications, but members such as bicycle cranks and frames are particularly required to have strength, rigidity and light weight. It can be applied to shafts and heads of sports members such as golf, automobile members such as doors and seat frames, and machine parts such as robot arms. Among them, in addition to strength and light weight, the member shape is complicated, and it can be preferably applied to a bicycle member such as a crank, which requires shape followability like this material, and automobile parts such as a seat panel and a seat frame.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not particularly limited thereto. The flat plate forming method and the mechanical property evaluation method used in this example were as follows.

<Flat plate forming method>
A prepreg 5 made of carbon fiber and thermosetting resin aligned in one direction is prepared, and from this, the fiber longitudinal direction and a direction shifted by 45 ° from the fiber longitudinal direction and shifted in two directions are 250 × 250 mm, respectively. Cut to size. Each cut prepreg base material was laminated on 16-layer pseudo-isotropic (([45/0 / -45 / 90] _2S to prepare a prepreg laminate 1. Then, on a mold having an outer dimension of 300 × 300 mm. After the prepreg laminate was placed, it was cured by heating under a heating condition of 150 ° C. for 30 minutes under a pressure of 6 MPa using a heating press molding machine, and the outer shape was similarly 300 × 300 × 1.7 mm. A molded body was obtained.

<Mechanical property evaluation method>
A tensile strength test piece having a length of 250 mm ± 1 mm and a width of 25 mm ± 0.2 mm was cut out from the obtained flat plate-shaped body. And according to the test method prescribed | regulated to this in JIS K-7073, the distance between gages was set to 150 mm, and the tensile strength was measured at a crosshead speed of 2.0 mm / min. 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.

Example 1
In FIG. 2, as a prepreg 5, a prepreg (Toray Industries, Inc.) wound up on a release paper having a thickness of 100 μm in which carbon fibers 7 aligned in one direction are impregnated with an epoxy resin and the surface is subjected to silicone coating treatment. Product P3052S-15: Fiber weight 150 g / m, resin content 33 wt%, thickness 0.15 mm) was obtained. And the prepreg base material 2c which cut | disconnected notches 6a and 6b as shown in FIG. 2 with respect to this prepreg 5 intermittently in the direction orthogonal to the fiber direction of carbon fiber was obtained.

The cut length L (La = Lb) is 10.5 mm, and the desired fiber length L2 is 30 mm. Moreover, the row | line | column of the adjacent notch 6b has shifted | deviated 10 mm in the fiber orthogonal direction with respect to the row | line | column of the notch 6a. That is, the pattern of the cut row is two patterns including the cut 6a and the cut 6b. Further, the cuts in adjacent rows are cut by 0.5 mm as the overlap width L1 of the cuts. Further, the number of fibers cut by any one cut is 23,625. The viscosity of the epoxy resin in an atmosphere at 25 ° C. was 2 × 10 ⁴ Pa · s, and the substrate had tackiness. From the prepreg base material with the cuts, the outer dimension is cut into a size of 250 mm × 250 mm in the fiber longitudinal direction and the direction shifted by 45 ° from the fiber longitudinal direction. ([45/0 / −45 / 90] _2S ).

  Next, a continuous fiber reinforced prepreg (Toray Industries, Inc. product F6343B-05) having an outer dimension of 300 × 300 mm and a plain weave was arranged on each side surface layer of the 16-layer prepreg laminated substrate. A prepreg laminate was produced. The laminate was placed on a mold having an outer dimension of the cavity portion of 300 mm × 300 mm, and then cured by a heating type press molding machine under a condition of 150 ° C. × 30 minutes under a pressure of 6 MPa, and 300 mm × 300 mm. A plate-like molded body of × 2.1 mm was obtained.

  In the obtained molded product, the fibers of the cut prepreg were evenly and sufficiently flowed to the end of the molded product without being accompanied by deformations such as swells of reinforcing fibers. Moreover, it was favorable plane smoothness without curvature. Moreover, as a result of evaluating the mechanical properties of the molded article by the above-described mechanical property evaluation method, the tensile strength was 440 MPa, the tensile modulus was 48 GPa, and the bending strength measured by applying a bending load in the 0/90 direction of plain weave was 630 MPa. The flexural modulus was as high as 52 GPa.

(Example 2)
In this example, the length of each cut is 12 mm, the cuts in adjacent rows are cut by L1 = 2 mm, and the number of fibers cut by any one cut is 27000. In the same manner as in Example 1 (16-layer pseudo isotropic lamination), a prepreg laminated substrate having a cut was produced.

  Next, 2 ply each of continuous fiber reinforced prepreg (Toray Industries, Inc. product P3052S-15) having a size of 300 × 300 mm and being formed in one direction on both side surface layers of the prepreg laminated base material (surface side [0/90]) , Back side [90/0]) A prepreg laminate was prepared. This prepreg laminate was hot press molded under the same molding conditions as in Example 1 using the same mold and heating press as in Example 1. As a result, a plate-shaped molded body having an outer dimension of 300 mm × 300 mm × 2.2 mm was obtained. The resulting molded body was not even accompanied by fiber undulations, and the fibers of the prepreg that had been cut into the ends of the molded body were flowing evenly and sufficiently. Moreover, it was favorable plane smoothness without curvature.

And as a result of applying the load to the continuous fiber direction and evaluating the mechanical properties of this molded body by the method described above, the tensile strength is 640 MPa, the tensile elastic modulus is 51 GPa, which is a higher value than in Example 1, and the bending strength is The bending elastic modulus was 840 MPa and the value of 62 GPa was very high.
(Comparative example)
This time, the prepreg base material used was exactly the same as in Example 1, and only the prepreg laminated base material having a notch consisting of 16 layers from which the continuous fiber reinforced prepregs arranged on both surface layers were removed was the same as in Example 1. Molding was performed under molding conditions to obtain a flat molded body having an outer dimension of 300 × 300 × 1.7 mm.

  The obtained molded product was free of warping of the fibers, the fibers were flowing evenly and sufficiently to the end of the molded product, and had good flat smoothness without warping as in Example 1.

  However, as a result of evaluating the mechanical properties of the molded body by the above-described method of continuous fibers, the tensile strength was 390 MPa, the tensile elastic modulus was 43 GPa, the bending strength was 560 MPa, and the bending elastic modulus was 42 GPa. The value was lower than 2.

  Table 1 below summarizes the data of the above examples and comparative examples.

  From Table 1 above, by placing a prepreg reinforced with continuous fibers (at least on one side) on the outermost layer of a prepreg laminated base material having a cut, the tensile strength and tensile elasticity compared to the case where such a prepreg is not arranged. It can also be seen that the bending strength and the bending elastic modulus are greatly improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is an overall view of a prepreg laminate according to the present invention, in which FIG. 1A is a plan view in which a prepreg substrate other than the lowermost prepreg substrate is partially broken and laminated, and FIG. 1 is a cross-sectional view taken along line AA in FIG. It is a partial top view which shows the example of a pattern of the base material which comprises the prepreg laminated base material 2 of FIG. It is a partial top view which shows the example of a pattern of the prepreg base material of FIG. 1 of a pattern different from FIG. It is a partial top view which shows the example of a pattern of the prepreg base material of FIG. 1 of a pattern different from FIG. It is a partial top view which shows the example of a pattern of the prepreg base material of FIG. 1 of a pattern different from FIG. FIG. 6 is a partial plan view showing a pattern example of the prepreg base material of FIG. 1 having a pattern different from that of FIG. 5. FIG. 7 is a partial plan view showing a pattern example of the prepreg base material of FIG. 1 having a pattern different from that of FIG. 6.

Explanation of symbols

1: Pre-preg laminated body 2: Pre-preg laminated base material 2a to 2d: Pre-preg base material having notches 3: Pre-preg base material (surface side) having continuous carbon fibers of the outermost layer as reinforcing fibers
4: Pre-preg base material (back side) with continuous carbon fiber of outermost layer as reinforcing fiber
5: Prepreg 6, 6a-6c: Cut 7: Reinforcing fiber 9: First cut row 10: Second cut row 11: Third cut row L: Cut length La: Cut length Lb of cut 6a : Cut length L1 of the cut 6b: Overlapping width L2: Desired fiber length L3: Length without cut L4: Length between the cuts 6a and 6b L5: The other length between the cuts 6a and 6b X: Longitudinal direction of reinforcing fiber Y: direction orthogonal to the longitudinal direction of reinforcing fiber

Claims (10)

In a prepreg laminate in which a plurality of layers of sheet-like prepregs obtained by impregnating a matrix resin with reinforcing fibers arranged in one direction and arranged in a plane,
(A) The sheet-shaped prepreg is made of continuous carbon fibers as reinforcing fibers, and the matrix resin as a thermosetting resin .
( B) The sheet-like prepreg includes a prepreg base material laminate obtained by laminating a plurality of prepreg base materials into which cuts of a finite length are intermittently cut in a direction crossing the fiber direction of the continuous carbon fibers, and the incision. And a continuous carbon fiber without reinforcing, and a prepreg substrate disposed on at least one side of the outermost layer of the prepreg substrate laminate ,
(C) All prepreg base materials constituting the prepreg base material laminate are in the direction in which the fibers cross the entire surface of the prepreg base material, and incision rows of 2 to 50 mm (L) are fiber directions of the reinforcing fibers. Are provided in a plurality of rows with a distance (L2) of 10 to 100 mm, the adjacent rows of the plurality of rows are shifted in the fiber orthogonal direction, and the cuts of the adjacent rows are the overlap width of the cuts A prepreg laminate characterized by being cut into each other at (L1) . 2. The prepreg laminate according to claim 1, wherein the continuous carbon fibers of the prepreg substrate disposed on at least one side of the outermost layer of the laminate are carbon fibers that are aligned only in one direction. . 2. The prepreg according to claim 1, wherein the prepreg base material disposed on at least one side of the outermost layer of the laminate includes a woven fabric woven with continuous carbon fibers aligned in two directions. Laminated body. The overlap width (L1) of the cuts that are cut into each other is 0.1 mm or more, and is 0.1 times or less the length of the shorter cut among the cuts in adjacent rows. The prepreg laminated body in any one of Claims 1-3 . The shape of the cut of the adjacent rows, the dimensions and any of the direction, the prepreg laminate according to any one of claims 1-4, wherein the wherein the at least. The prepreg laminate according to any one of claims 1 to 5 , wherein the cuts are provided at equal intervals in a direction crossing a fiber direction of the reinforcing fibers. The prepreg laminate according to any one of claims 1 to 6, wherein a direction in which the cuts cross is a direction orthogonal to a fiber direction of the carbon fiber. The prepreg laminate according to any one of claims 1 to 7 , wherein the number of fibers cut by any one cut is in the range of 5,000 to 50,000. The prepreg laminate according to any one of claims 1 to 8 , wherein at least the prepreg base material containing the continuous carbon fibers as reinforcing fibers is shaped in advance into a product shape. A fiber-reinforced plastic obtained by heating and curing the prepreg laminate according to any one of claims 1 to 9 .

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