JP2014051014A - Method for producing fiber-reinforced composite material and intermediate base material for fiber-reinforced composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fiber-reinforced composite material capable of providing excellent surface quality to a molded article thereof without complicating constitution of molding steps and molding equipment, to which a molding process where continuous pressurizing or position control of a mobile mold during impregnation and curing of a resin is not necessary is applicable.SOLUTION: An intermediate base material for a fiber-reinforced composite material 11 comprises a reinforced base material 14 in which laminated fiber layers 12 are connected with binding yarn 13 and a plurality of mold release sheets 15 integrated with the reinforced base material 14 at both sides in the lamination direction thereof. The intermediate base material 11 is set in a mold and a composite material as a primary molded article is taken out from the mold after impregnation and curing of a matrix resin. Then the release sheets 15 in which sink marks generated are removed from the primary article to obtain a molded article as a product without sink mark.

Description

  The present invention relates to a method for producing a fiber reinforced composite material and an intermediate base material for fiber reinforced composite material, and more particularly, a fiber reinforced composite material capable of producing a fiber reinforced composite material having excellent surface quality using a laminated fiber layer as a reinforced base material. The present invention relates to a method for producing a material and an intermediate substrate for a fiber-reinforced composite material.

  Several molding methods are known for molding fiber reinforced plastic (FRP) using a matrix as a resin among fiber reinforced composite materials. To mold FRP using a laminated fiber layer as a reinforced base material The RTM (Resin Transfer Molding) method is often used because of advantages such as a short molding cycle and high productivity. In the RTM method, a reinforced substrate is placed in a cavity formed in a mold, a resin is injected into the cavity and impregnated into the reinforced substrate, the resin is cured, and the mold is removed after curing. An FRP molded product is obtained. Examples of the laminated fiber layer include a woven fabric, a knitted fabric, a nonwoven fabric laminate, and a three-dimensional fiber structure in which the laminated fiber layers are bonded with a binding yarn.

  In a molded product molded by the RTM method, the sink of the surface of the molded product is usually generated due to resin impregnation property or resin curing shrinkage. In order to prevent the occurrence of sink marks, the inside of the mold cavity is decompressed through the vent, the synthetic resin is injected and filled into the cavity from the injection port, and the vent is inserted into the cavity from the cavity. A molding method has been proposed in which the overflowed synthetic resin is pressurized so as to resist the overflow pressure from the vent (Patent Document 1).

  Also, using a molding device that is arranged facing the fixed mold, can be moved close to and away from the fixed mold, and can control the position of the movable mold with respect to the fixed mold, the movable mold is used as a resin until curing is completed. There has also been proposed a molding method in which a surface pressure is continuously applied, the resin impregnation property is improved, and the movable mold is moved following the sink (Patent Document 2).

JP 2007-1179 A JP 2010-221642 A

  In the method of Patent Document 1, in order to prevent the shrinkage due to the curing shrinkage of the resin from concentrating on the surface, the resin needs to be supplied to the surface following the sink. Cannot be supplied. Also in the method of Patent Document 2, it is difficult to control the movable position following the sink.

  The present invention has been made in view of the above problems, and its purpose is to apply a molding method that does not require continuous pressure application or movable position control during resin impregnation and curing. Another object of the present invention is to provide a method for producing a fiber reinforced composite material and an intermediate substrate for fiber reinforced composite material, which can obtain a fiber reinforced composite material with excellent surface quality of a molded product without complicating the structure of the molding equipment. .

  In order to achieve the above object, the method for producing a fiber-reinforced composite material according to claim 1 is characterized in that the reinforcing group is integrated in a state in which a defect-absorbing layer is integrated on at least one side of a reinforcing substrate made of a laminated fiber layer. The material is set in a mold, and the defect absorbing layer is removed from the molded article after impregnating and curing the matrix resin on the reinforced substrate. Here, “the state in which the defect absorption layer is integrated” does not mean only a configuration in which the defect absorption layer is bonded to the laminated fiber layer with a binding yarn, but a bonding agent such as an adhesive or a pressure-sensitive adhesive. It also means a state where the defect absorbing layer is bonded to the laminated fiber layer and a state where the defect absorbing layer is pressed against the laminated fiber layer by the pressing action of the mold. In addition, “impregnation and curing of matrix resin” is not limited to impregnation and curing of uncured thermosetting resin, but also impregnation of thermoplastic resin monomer, polymerization (curing) or molten thermoplastic resin. It also means solidification by cooling.

  In the conventional molding method, the resin is supplied or the movable press control (position control) is performed so as not to cause sink marks on the surface of the molded product when the laminated fiber layer is impregnated and cured. It was. However, in the present invention, at the time of impregnation and curing of the resin, the idea and idea of preventing the occurrence of sink marks on the surface of the molded product is changed, and without preventing the occurrence of sink marks on the surface of the molded product, A portion for facilitating removal of the molded product from the mold is used as a defect absorbing layer, and sink marks are generated in the defect absorbing layer. Then, the defect absorbing layer in which sink marks are generated is removed from the molded product so that the target product does not have sink marks. Therefore, even if the molding conditions at the time of impregnation and curing of the resin fluctuate and the size of the sink changes, the sink is removed together with the defect-absorbing layer. Therefore, it is possible to apply molding methods that do not require continuous pressure application and movable position control during resin impregnation and curing, and the surface quality of the molded product can be improved without complicating the configuration of the molding process and molding equipment. An excellent fiber reinforced composite material can be produced.

  According to a second aspect of the present invention, in the first aspect of the present invention, when the matrix resin is impregnated and cured, a defect (sink) is generated in the defect absorbing layer disposed on one side of the reinforced substrate. The temperature of the mold is controlled.

  In a normal molding method, when the resin is impregnated and cured in the laminated fiber layer, the resin cures outward from the central portion of the laminated fiber layer, and sink marks are generated on both sides. In the present invention, the temperature of the mold is controlled so that defects are generated in the defect absorbing layer disposed on one side of the reinforced substrate (laminated fiber layer) when the matrix resin is impregnated and cured. Therefore, it is not necessary to integrate the defect absorbing layer on both sides of the reinforced base material, and the operation of attaching the defect absorbing layer to the reinforced base material and the operation of removing the defect absorbing layer from the molded product after molding become easy.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein the matrix resin is a thermosetting resin. The matrix resin constituting the fiber-reinforced composite material can be either a thermosetting resin or a thermoplastic resin, but the thermosetting resin is easier to impregnate and cure the resin.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the defect absorbing layer is a release sheet. In this invention, since a release sheet is used as the defect absorption layer, it is not necessary to provide a defect absorption layer separately from the release sheet required when a fiber reinforced composite material is manufactured using a mold.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the reinforcing base material is formed by bonding laminated fiber layers with a binding yarn, and the defect absorbing layer is It is integrated with the reinforced substrate by a binding yarn. In this invention, since the integration of the reinforcing substrate and the defect absorbing layer is performed by the bonded yarn of the laminated fiber layer, the number of manufacturing steps of the laminated fiber layer in which the defect absorbing layer is integrated is reduced.

  In the intermediate base material for fiber-reinforced composite material according to the sixth aspect of the invention, the defect absorbing layer is integrated on at least one side of the reinforcing base material composed of the laminated fiber layers in the fiber lamination direction. When the manufacturing method of the invention according to claim 1 is carried out, it is necessary to set the reinforced base material in a mold in a state in which the defect absorbing layer is integrated on at least one side of the reinforced base material composed of laminated fiber layers. . The thickness of the defect absorbing layer and the number of sheets used vary depending on the thickness of the laminated fiber layer, the fiber volume content, the amount of cure shrinkage of the resin, etc., and if the defect absorbing layer is not integrated with the laminated fiber layer, The number of man-hours for setting the laminated fiber layer and the defect absorbing layer having an appropriate thickness and number of sheets in the mold increases. However, the intermediate substrate for fiber-reinforced composite material of the present invention has a laminated fiber layer and an appropriate thickness because the defect absorbing layer is integrated on at least one side in the fiber lamination direction of the reinforcing substrate composed of the laminated fiber layer. The number of man-hours for setting the number and the number of defect absorbing layers in the mold is reduced.

  The invention according to claim 7 is the invention according to claim 6, wherein the defect absorbing layer is a release sheet. In this invention, since the release sheet is used as the defect absorption layer, it is necessary to provide the defect absorption layer separately from the release sheet necessary for producing an intermediate substrate for fiber-reinforced composite material using a mold. Absent.

  The invention according to an eighth aspect is the invention according to the seventh aspect, wherein the release sheet comprises a plurality of sheets. When the appropriate value of the thickness of the defect absorbing layer varies depending on the thickness of the laminated fiber layer, the fiber volume content, the amount of cure shrinkage of the resin, etc., and the defect absorbing layer is formed with a single release sheet, Release sheets having various thicknesses are required corresponding to differences in thickness, fiber volume content, cure shrinkage of resin, and the like. However, when the release sheet is composed of a plurality of sheets, it is possible to cope with changes in the thickness of the laminated fiber layer, the fiber volume content, the amount of cure shrinkage of the resin, etc. by changing the number of the same release sheet. .

  The invention according to claim 9 is the invention according to any one of claims 6 to 8, wherein the reinforcing base material is formed by bonding laminated fiber layers with a binding yarn, and the defect absorbing layer is It is integrated with the reinforced substrate by a binding yarn. In this invention, since the integration of the reinforcing substrate and the defect absorbing layer is performed by the bonded yarn of the laminated fiber layer, the number of manufacturing steps of the laminated fiber layer in which the defect absorbing layer is integrated is reduced.

  The invention described in claim 10 is the invention described in claim 9, wherein the binding yarn is soluble in a matrix resin of a fiber-reinforced composite material. Therefore, in this invention, compared with the case where the binding yarn is insoluble in the matrix resin, the work of removing the release sheet from the molded product after the resin impregnation and curing is facilitated.

  The invention according to claim 11 is the invention according to claim 10, wherein the matrix resin is a thermosetting resin, and the binding yarn is made of phenoxy resin fiber. The matrix resin constituting the fiber-reinforced composite material can be either a thermosetting resin or a thermoplastic resin, but the thermosetting resin is easier to impregnate and cure the resin. When the binding yarn is made soluble in the matrix resin, the binding yarn becomes a part of the matrix resin and becomes a resin rich portion. Microcracks are likely to occur in the resin-rich portion, but when the binding yarn is made of phenoxy resin fiber, the binding yarn is soluble in a thermosetting resin (for example, epoxy resin). The phenoxy resin has a long molecular chain, so it is flexible and flexible, and has a hydroxyl group as a hydrophilic group and a hydrocarbon group as a hydrophobic group, so that the toughness of the resin-rich part is improved, and microcracks Is unlikely to occur.

  According to the present invention, it is possible to apply a molding method that does not require continuous pressure application or movable mold position control during resin impregnation and curing, and without complicating the configuration of the molding process and molding equipment. It is possible to provide a method for producing a fiber-reinforced composite material and an intermediate substrate for fiber-reinforced composite material, which can obtain a fiber-reinforced composite material having excellent surface quality.

(A) is a schematic perspective view of the intermediate base material for fiber reinforced composite materials of 1st Embodiment, (b) is a schematic cross section. The schematic block diagram of the manufacturing apparatus of a fiber reinforced composite material. The schematic cross section of the intermediate base material for fiber reinforced composite materials of 2nd Embodiment. The schematic block diagram of a manufacturing apparatus.

(First embodiment)
A first embodiment embodying the present invention will be described below with reference to FIGS.
As shown in FIGS. 1 (a) and 1 (b), an intermediate base material (intermediate base material for fiber reinforced composite material) 11 is a fiber lamination direction of a reinforcing base material 14 in which a laminated fiber layer 12 is bonded with a binding yarn 13. A plurality of release sheets 15 as defect absorbing layers are integrated on both sides of the sheet. That is, in the intermediate base material 11, the defect absorbing layer is integrated on at least one side of the reinforcing base material 14 made of the laminated fiber layer 12 in the fiber lamination direction.

  The laminated fiber layer 12 is arranged so that the continuous fibers are at least biaxially oriented. In this embodiment, as shown in FIG. 1B, the laminated fiber layer 12 is a continuous fiber 16a having an arrangement angle of 0. A plurality of fiber layers 12a composed of continuous fibers 16b composed of continuous fibers 16b having an arrangement angle of 90 degrees are alternately laminated to form a biaxially oriented laminated fiber layer 12. The laminated fiber layer 12 has a thickness of, for example, several mm. For example, carbon fibers are used as the continuous fibers 16 a and 16 b and the binding yarn 13. Carbon fiber has a number of filaments of about several hundred to several tens of thousands, and the number of fiber bundles suitable for the required performance is selected.

  The binding yarn 13 is disposed on the other side so as to be folded back on the outer surface of the release sheet 15 disposed on one side of the laminated fiber layer 12 (the lower surface side in FIGS. 1A and 1B). Retaining yarns (ear yarns) inserted in a loop shape from the outer surface of the mold sheet 15 and inserted in a loop portion protruding from one outer surface and arranged in a direction orthogonal to the arrangement direction of the binding yarns 13 It is prevented from coming off by 17. The fiber layers 12 a and 12 b of the laminated fiber layer 12 are bonded together with the binding yarn 13 and the retaining yarn 17, and a plurality of release sheets 15 are integrated on both sides of the laminated fiber layer 12.

  As the release sheet 15, for example, a cloth formed of glass fiber surface-treated with silicone or fluororesin is used. The release sheet 15 has a thickness of 25 to 330 μm per sheet. The thickness of the release sheet 15 depends on the thickness of the laminated fiber layer 12, the fiber volume content (Vf), the amount of cure shrinkage of the resin, and the like. The sheath number is set to an appropriate value. For example, a few or several release sheets 15 are used.

Next, the manufacturing method of the fiber reinforced resin as a fiber reinforced composite material using the intermediate base material 11 comprised as mentioned above is demonstrated.
The production of the fiber reinforced resin is performed using a VaRTM method (vacuum RTM method) which is a kind of RTM method. FIG. 2 shows a configuration of a manufacturing apparatus used in the VaRTM method. The manufacturing apparatus includes a molding die 20 and a bag film 22 that covers the molding surface 21 side of the molding die 20. The molding die 20 is provided with a seal portion 23 that surrounds the periphery of the molding surface 21, and the bag film 22 covers the molding surface 21 with its peripheral edge pressed against the seal portion 23. The mold 20 is configured such that the temperature can be adjusted by a heating device (not shown).

  The manufacturing apparatus includes a vacuum pump 24, one end of a decompression pipe 25 penetrating the seal portion 23 is connected to the vacuum pump 24, and a resin recovery tank (trap) 26 and an opening / closing valve 27 are provided in the middle of the decompression pipe 25. ing. The manufacturing apparatus includes a resin storage tank 28 as a matrix resin storage section, and one end of a resin supply pipe 29 penetrating the seal section 23 is connected to the resin storage tank 28. An on-off valve 30 is provided in the middle of the resin supply pipe 29.

Next, the manufacturing method of the fiber reinforced resin using the said manufacturing apparatus is demonstrated.
First, after the intermediate base material 11 and the flow media 31 are arranged on the molding surface 21 of the molding die 20, the bag film 22 is arranged in a state where the peripheral edge portion thereof corresponds to the seal portion 23. That is, the matrix resin is arranged in a state where it can be supplied from the flow media 31 side while being covered with the bag film 22 from the outer surface side of the intermediate substrate 11. In that state, the on-off valve 30 is closed, and the on-off valve 27 is opened to drive the vacuum pump 24 and the space defined by the molding surface 21 and the bag film 22 (hereinafter referred to as a resin injection space). Depressurize to near vacuum. The flow media 31 disposed on the intermediate substrate 11 is pressed against the intermediate substrate 11 by the bag film 22 as the resin injection space is depressurized, and the matrix resin is injected in this state. A thermosetting resin such as an epoxy resin is used as the matrix resin.

  With the temperature of the mold 20 maintained at a predetermined temperature, the on-off valve 30 is opened, and the matrix resin in the resin storage tank 28 is injected into the resin injection space. The matrix resin injected into the resin injection space spreads along the entire surface of the intermediate substrate 11 by the action of the flow media 31, and then is impregnated throughout the intermediate substrate 11 through the release sheet 15. The matrix resin injected into the resin injection space and overflowing from the resin injection space is recovered in the resin recovery tank 26 via the decompression pipe 25. After a predetermined time set in advance, the on-off valve 27 is closed and the driving of the vacuum pump 24 is stopped. Further, the on-off valve 30 is closed. Then, the temperature of the mold 20 is raised to a predetermined temperature set in advance for a predetermined time, and the matrix resin is cured to form a composite material as a primary molded product. After the resin is completely cured, the inside of the resin injection space is returned to atmospheric pressure, the bag film 22 is removed from the molding die 20, and the composite material is removed from the molding surface 21. In this composite material, the entire intermediate substrate 11 is impregnated with resin and cured. Thereafter, after removing the release sheets 15 on both sides, a molded product that becomes a product is obtained by removing the burrs. The release sheets 15 on both sides are removed by, for example, removing the release sheets 15 while leaving the binding yarns 13 while tearing the release sheets 15.

  When the matrix substrate is impregnated and cured with respect to the intermediate base material 11, sink marks are generated on the surface of the primary molded product. Since sink marks are generated in the part of the release sheet 15, removing the release sheet 15 from the primary molded product provides a molded product as a product free from sink marks.

According to this embodiment, the following effects can be obtained.
(1) In the method for producing a fiber reinforced composite material, the intermediate base material 11 in which the release sheet 15 (defect absorbing layer) is integrated on at least one side of the reinforced base material 14 made of the laminated fiber layer 12 is set in the mold 20. The mold release sheet 15 is removed from the molded product (primary molded product) after the reinforced base material 14 is impregnated with the matrix resin and cured. That is, unlike the conventional molding method, the part of the release sheet 15 for making it easy to remove the molded product from the mold 20 without preventing the occurrence of sink marks on the surface of the molded product during resin impregnation and curing. The release sheet 15 in which sink marks were generated was removed from the molded product (primary molded product) so that the target product did not have sink marks. Therefore, even if the molding conditions at the time of resin impregnation and curing vary and the size of the sink marks changes, the sink marks are removed together with the release sheet 15, so there is little adverse effect on the variations in molding conditions. Therefore, it is possible to apply molding methods that do not require continuous pressure application and movable position control during resin impregnation and curing, and the surface quality of the molded product can be improved without complicating the configuration of the molding process and molding equipment. An excellent fiber reinforced composite material can be produced. Moreover, the precision of the thickness of a molded product can also be improved. Further, since the release sheet 15 is used as the defect absorbing layer, it is not necessary to provide the defect absorbing layer separately from the release sheet 15 necessary when the fiber reinforced composite material is manufactured using the mold 20.

  (2) The matrix resin is a thermosetting resin. The matrix resin constituting the fiber-reinforced composite material can be either a thermosetting resin or a thermoplastic resin, but the thermosetting resin is easier to impregnate and cure the resin.

  (3) In the intermediate base material 11, a plurality of release sheets 15 are integrated on at least one side of the reinforcing base material 14 in which the laminated fiber layers 12 are joined by the binding yarns 13 in the fiber lamination direction. The appropriate values for the thickness and number of sheets used of the release sheet 15 vary depending on the thickness of the laminated fiber layer 12, the fiber volume content, the amount of cure shrinkage of the resin, and the release sheet 15 is integrated with the laminated fiber layer 12. If not, the number of man-hours for setting the laminated fiber layer 12 and the release sheets 15 of appropriate thickness and number on the mold 20 is increased. However, since the intermediate substrate 11 has a plurality of release sheets 15 integrated on at least one side in the fiber lamination direction of the reinforcing substrate 14 in which the laminated fiber layer 12 is bonded with the binding yarns 13, the laminated fiber layer 12 And the man-hour at the time of setting the release sheet 15 of appropriate thickness and number of sheets to the shaping | molding die 20 decreases. Further, when the release sheet 15 is integrated with the intermediate base material 11 by the binding yarn 13, the intermediate base material 11 can be easily handled.

  When the appropriate value of the thickness of the defect-absorbing layer varies depending on the thickness of the laminated fiber layer 12, the fiber volume content, the amount of cure shrinkage of the resin, etc., and the defect-absorbing layer is formed with one release sheet 15, the laminated fiber The release sheets 15 having various thicknesses are required corresponding to differences in the thickness of the layer 12, the fiber volume content, the curing shrinkage amount of the resin, and the like. However, when the release sheet 15 is composed of a plurality of sheets, by changing the number of the release sheets 15 having the same thickness, the thickness of the laminated fiber layer 12, the fiber volume content, the amount of cure shrinkage of the resin, and the like are changed. It can correspond to.

  (4) Since the release sheet 15 is integrated on both sides of the reinforced base material 14, even if sink marks occur on both sides of the primary molded product by impregnating and curing the matrix resin by a general method. There is no hindrance.

(Second Embodiment)
Next, a second embodiment will be described with reference to FIGS. In this embodiment, a plurality of release sheets 15 are integrated on one side of the intermediate base material 11, and when a fiber reinforced resin is manufactured, a sink is disposed on one side of the reinforced base material 14. The point which performs RTM method so that it may generate | occur | produce in the part of the type | mold sheet | seat 15 differs from the said 1st Embodiment. In addition, about the part similar to 1st Embodiment, the same code | symbol is attached | subjected and the detailed description is abbreviate | omitted.

As shown in FIG. 3, in the intermediate base material 11, the release sheet 15 is integrated only on the side opposite to the side on which the retaining thread 17 on one side of the reinforced base material 14 is arranged.
As shown in FIG. 4, a molding die 41 constituting the manufacturing apparatus is composed of a lower die 42 and an upper die 43. The lower die 42 has a cavity 44 corresponding to the shape of the fiber reinforced resin molded product to be formed. The upper mold 43 is formed with an injection hole 45 and a discharge hole 46 communicating with the cavity 44. One end of the injection hole 45 is formed at a position corresponding to one end of the cavity 44, and the other end is connected to the resin injection device 48 via an injection pipe 47. As the resin injection device 48, a known device is used, and the resin stored in the tank is pumped out. The injection pipe 47 is provided with an on-off valve 49 and a pressure gauge 50 on the cavity 44 side from the on-off valve 49.

  One end of the discharge hole 46 is formed at a position corresponding to the other end of the cavity 44, and the other end is connected to the decompression pump 52 via the suction pipe 51. The suction pipe 51 is provided with an opening / closing valve 53, and a trap 54 is provided closer to the decompression pump 52 than the opening / closing valve 53. An annular groove is formed on the upper surface of the lower mold 42, and the sealing performance of the cavity 44 in the mold closed state is secured by the sealing material 55 accommodated in the annular groove.

  The lower mold 42 and the upper mold 43 are provided with heat medium pipes 56 and 57 through which a heat medium flows to adjust the temperature of the mold 41. The resin injection device 48, the decompression pump 52, and the on-off valves 49 and 53 are operated or switched by commands from a control device (not shown). Further, the control device adjusts the temperature of the mold 41 based on a detection signal from a temperature sensor (not shown) that detects the temperatures of the lower mold 42 and the upper mold 43.

Next, a method for producing a fiber reinforced resin molded product (FRP molded product) will be described.
With the mold release agent applied to the wall surface of the cavity 44 of the lower mold 42, the intermediate substrate 11 is placed in the cavity 44 of the mold 41, the mold 41 is clamped, and then the mold 41 is heated. To do. The main purpose of this heating is to increase the fluidity of the uncured resin injected into the cavity 44. Then, the on-off valve 49 is closed and the decompression pump 52 is driven in a state where the on-off valve 53 is opened to decompress the inside of the cavity 44 to a state close to a vacuum. Subsequently, in a state where the inside of the cavity 44 is decompressed, the on-off valve 49 is opened and uncured thermosetting resin is injected from the resin injection device 48 into the cavity 44 through the injection hole 45.

  The resin injecting device 48 sends out the resin so that the sent out resin has a constant flow rate. The resin injected into the cavity 44 is impregnated in the intermediate substrate 11 and moves while pushing the bubbles remaining in the intermediate substrate 11. Then, the resin gradually fills the cavity 44 from below, and the bubbles move to the upper side of the cavity 44 and move from the inside of the cavity 44 to the discharge hole 46.

  After the resin injection into the cavity 44 is continued and the resin injection into the cavity 44 is completed, the on-off valves 49 and 53 are closed, and the operation of the resin injection device 48 and the decompression pump 52 is stopped. The temperature of the heat medium supplied to the heat medium pipes 56 and 57 is increased, and heating is continued until the resin is completely cured. The temperature of the heat medium supplied to the heat medium pipes 56 and 57 is controlled so that a temperature difference of 5 to 30 ° C. is formed between the upper mold 43 and the lower mold 42 and the lower mold 42 side is at a high temperature.

  After the curing of the resin is completed, the mold 41 is opened, and the fiber reinforced resin molded product is taken out from the mold 41. This completes the production of the fiber reinforced resin molded product. Note that the determination of the completion of the resin injection into the cavity 44 and the completion of the resin curing was performed by, for example, obtaining the elapsed time from the start of the resin injection into the cavity 44 in advance by a test. It is done by reaching the time.

  In a normal molding method, when the resin is impregnated and cured with respect to the intermediate base material 11, the resin hardens from the central portion of the laminated fiber layer 12 toward the outside, and sink marks are generated on both sides of the intermediate base material 11. In the present invention, the temperature of the mold 41 is controlled so that defects occur in the part of the release sheet 15 disposed on one side of the reinforced base material 14, that is, on one side of the intermediate base material 11, during the impregnation and curing of the matrix resin. To do. Specifically, temperature control is performed so that the lower mold 42 side is at a predetermined temperature and a higher temperature than the upper mold 43, the curing of the matrix resin proceeds from the lower mold 42 side, and the side on which the release sheet 15 is disposed is the last. To harden. As a result, when the matrix resin is impregnated and cured, a defect (sink) occurs in the part of the release sheet 15 disposed on one side of the intermediate base material 11.

Therefore, according to this embodiment, in addition to the same effects as (1), (2), and (3) of the first embodiment, the following effects can be obtained.
(5) During the impregnation and curing of the matrix resin, the temperature of the mold 41 is controlled so that defects (sinks) occur in the part of the release sheet 15 disposed on one side of the reinforced substrate 14. Therefore, it is not necessary to integrate the release sheet 15 on both sides of the reinforced base material 14, and the work of attaching the release sheet 15 to the reinforced base material 14 and the work of removing the release sheet 15 from the molded product after molding are easy. Become.

  (6) Since the intermediate substrate 11 faces the lower mold 42 through the mold release agent on the side where the release sheet 15 is not disposed, the surface state of the molded product is when the release sheet 15 exists. In comparison, the surface state (roughness) of the lower mold 42 is reflected. Therefore, the surface roughness of the molded product can be adjusted by the surface roughness of the lower mold 42.

The embodiment is not limited to the above, and may be embodied as follows, for example.
The thermosetting resin as the matrix resin is not limited to an epoxy resin, and for example, an unsaturated polyester resin, a phenol resin, or a vinyl ester resin may be used.

  ○ The matrix resin is not limited to a thermosetting resin, and a thermoplastic resin may be used. When a thermoplastic resin is used as the matrix resin, the intermediate substrate 11 is impregnated with a thermoplastic resin by a general impregnation method such as a melt impregnation molding method, and then cooled to form a composite material. As the thermoplastic resin, for example, nylon, polybutylene terephthalate, polycarbonate or the like is used. When using a thermoplastic resin, the method is not limited to a method using a polymerized thermoplastic resin. As in the case of a thermosetting resin, the intermediate substrate 11 is impregnated in the state of a monomer before polymerization and then polymerized. Also good. Examples of the thermoplastic resin to be impregnated in the monomer state include a polyamide (nylon) monomer (for example, ε-caprolactam).

  The fiber reinforced composite material only needs to have at least the laminated fiber layer 12 as the reinforcing base material 14, and the binding yarn 13 may not be present in the molded product. In the case of manufacturing a fiber reinforced composite material in which the binding yarn 13 is not present in the molded product, fibers that are soluble in the matrix resin are used as the binding yarn 13 constituting the intermediate substrate 11. For example, when the matrix resin is a thermosetting resin, a phenoxy resin fiber or a polyamide (nylon) fiber is used for the binding yarn 13 and the retaining yarn 17. When the matrix resin is a thermoplastic resin, fibers of the same system as the matrix resin are used for the binding yarn 13 and the retaining yarn 17. In these cases, it is easier to remove the release sheet 15 from the molded product after the resin is impregnated and cured as compared with the case where the binding yarn 13 is insoluble in the matrix resin.

  When the phenoxy resin fiber soluble in the matrix resin is used for the binding yarn 13, the fiber reinforced composite material has a phase in which the phenoxy resin is mixed with the matrix resin at the location where the binding yarn 13 exists. In the fiber reinforced composite material, a resin-rich portion is likely to exist in the vicinity of the portion where the binding yarn 13 is present, and microcracks are easily generated in the resin-rich portion. However, when phenoxy resin is mixed, phenoxy resin is flexible because it has a long molecular chain, and has excellent flexibility, and also has good adhesion because it has a hydroxyl group as a hydrophilic group and a hydrocarbon group as a hydrophobic group. The toughness of the resin rich portion is improved and the occurrence of microcracks is suppressed.

  ○ The binding yarn 13 for bonding the laminated fiber layer 12 is not limited to the configuration in which the laminated fiber layer 12 is inserted in a folded shape from one surface and is prevented from being removed by the retaining yarn 17, but one needle is used. It may be a stitch yarn that repeatedly inserts the binding yarn 13 into the laminated fiber layer 12 from one surface and changes the penetration position on the other surface to be turned back.

  ○ When the fibers (thickness direction yarns) arranged in the direction intersecting the fiber layers 12a and 12b of the laminated fiber layer 12 are required as the reinforcing base material 14 of the fiber reinforced composite material, the release sheet 15 is used as an intermediate base. Only one side of the material 11 is integrated by the binding yarn 13 and the retaining thread 17, and the release sheet 15 is disposed on the retaining thread 17 side. The retaining thread 17 is made of a fiber that is soluble in the matrix resin. In this case, the retaining yarn 17 is dissolved in the matrix resin by impregnation with the matrix resin, but the binding yarn 13 remains as a thickness direction yarn. Moreover, when the retaining thread 17 is dissolved, the release sheet 15 can be easily removed from the molded product.

  In the case where a thread in the thickness direction is required as the reinforcing substrate 14, the release sheet 15 is disposed on at least one side of the laminated fiber layer 12 in which the fiber layers 12a and 12b are bonded with the bonding yarn 13 insoluble in the matrix resin. Thus, the intermediate substrate 11 may be formed by integrating the release sheet 15 with the laminated fiber layer 12 with the binding yarn 13 soluble in the matrix resin.

  The structure of the intermediate substrate 11 in which a plurality of release sheets 15 are integrated on at least one side in the fiber lamination direction of the reinforcing substrate 14 in which the laminated fiber layer 12 is bonded with the bonding yarn 13 is formed by the bonding yarn 13. It is not limited to an integrated configuration. For example, the release sheet 15 may be integrated with the laminated fiber layer 12 with a welding powder, an adhesive, or an adhesive.

  The release sheet 15 may be integrated with the intermediate substrate 11 before at least the intermediate substrate 11 is set in the molds 20 and 41 and the matrix resin is supplied. It is not necessary to be integrated with 11 so that movement is possible. For example, when the intermediate substrate 11 is set on the molds 20 and 41, the release sheet 15 is set between the intermediate substrate 11, the molds 20 and 41, and the bag film 22, and the molds 20 and 41 and It is good also as a structure hold | maintained in a predetermined position with the pressing force of the bag film 22. FIG.

  O As a defect absorption layer, you may use a nonwoven fabric, for example. When the depth of sink marks (defects) is deep, it is necessary to increase the number of release sheets 15 or to use a thick release sheet 15 without increasing the number of sheets. Alternatively, a single release sheet 15 may be provided by providing a defect absorbing layer.

  ○ When sink marks are concentrated only on one side where the release sheet 15 of the intermediate base material 11 is arranged by controlling the temperature of the molding die 41, the ultimate temperature is the same, and a predetermined range, for example, on the lower die 42 and the upper die 43, for example Alternatively, the temperature may be controlled to be increased by providing a time difference so that a temperature difference of 5 to 30 ° C. is obtained.

  ○ Not only in the RTM method, but also in the VaRTM method, the thermosetting resin is cured from the molding surface 21 side by controlling the temperature of the molding die 20, and the release sheet 15 disposed on the bag film 22 side is used. You may make it sink.

The matrix resin impregnation and curing treatment for the intermediate base material 11 is not limited to the RTM method or the VaRTM method, and an RFI (resin film infusion) method may be used.
The laminated fiber layer 12 in which the fiber layers 12a and 12b made of the continuous fibers 16a and 16b are laminated may be at least biaxially oriented, and the arrangement angle of the continuous fibers is not limited to the combination of 0 degree and 90 degrees. For example, in addition to the arrangement angles of 0 degrees and 90 degrees, a fiber layer composed of continuous fibers with an arrangement angle of +45 degrees and −45 degrees is provided to form a 4-axis orientation, or a continuous fiber with an arrangement angle of 0 degrees or 90 degrees. Or a combination of bias fiber bundles arranged obliquely with respect to the continuous fibers.

  ○ The continuous fiber and the thickness direction yarn are not limited to carbon fiber, and glass fiber, aramid fiber, or the like may be used as long as the required performance of the composite material of the molded product is satisfied.

  DESCRIPTION OF SYMBOLS 11 ... Intermediate base material as intermediate base material for fiber reinforced composite material, 12 ... Laminated fiber layer, 13 ... Bonding yarn, 14 ... Reinforcement base material, 15 ... Release sheet as defect absorbing layer, 20, 41 ... Mold .

Claims (11)

  The reinforced base material is set in a molding die in a state where a defect absorbing layer is integrated on at least one side of the reinforced base material composed of a laminated fiber layer, and after the impregnation and curing of the matrix resin to the reinforced base material, A method for producing a fiber-reinforced composite material, wherein the defect absorbing layer is removed.   The fiber-reinforced composite material according to claim 1, wherein the temperature of the mold is controlled so that a defect is generated in the defect absorbing layer disposed on one side of the reinforced base material when the matrix resin is impregnated and cured. Method.   The method for producing a fiber-reinforced composite material according to claim 1, wherein the matrix resin is a thermosetting resin.   The method for producing a fiber-reinforced composite material according to any one of claims 1 to 3, wherein the defect absorbing layer is a release sheet.   The laminated fiber layer of the reinforced base material is bonded with a binding yarn, and the defect absorbing layer is integrated with the reinforced base material with the binding yarn. Manufacturing method of fiber reinforced composite material.   An intermediate substrate for a fiber-reinforced composite material, wherein a defect-absorbing layer is integrated on at least one side of a reinforcing substrate composed of a laminated fiber layer in the fiber lamination direction.   The intermediate substrate for fiber-reinforced composite material according to claim 6, wherein the defect absorbing layer is a release sheet.   The intermediate substrate for fiber-reinforced composite material according to claim 7, wherein the release sheet comprises a plurality of sheets.   The laminated fiber layer of the reinforced base material is bonded with a binding yarn, and the defect absorbing layer is integrated with the reinforced base material with the binding yarn. Intermediate substrate for fiber reinforced composites.   The intermediate substrate for a fiber-reinforced composite material according to claim 9, wherein the binding yarn is soluble in a matrix resin of the fiber-reinforced composite material.   The intermediate substrate for fiber-reinforced composite material according to claim 10, wherein the matrix resin is a thermosetting resin, and the binding yarn is made of phenoxy resin fiber.