JP2012214042A - Method of manufacturing fiber-reinforced plastic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a fiber-reinforced plastic using a mold and a bag material, wherein the fiber-reinforced plastic of a complex shape superior in surface smoothness can be manufactured without preparing an upper mold or a press plate shaped into a product shape in advance even when the mold has a complex shape having a curved or bent shape.SOLUTION: This method of manufacturing a fiber-reinforced plastic includes the steps of: (a) an arrangement step of arranging a molding material including at least a fiber-reinforced substrate and a resin sheet material having smoothness equivalent to or higher than the surface roughness required in the final product on a mold having a curved or bent shape; (b) a shaping/heating step of pressing the molding material against the mold and along the mold and shaping and heating the molding material; (c) a curing step of curing a matrix resin impregnated into the fiber-reinforced substrate; and (d) the removal step of removing the resin sheet material from the fiber-reinforced substrate.

Description

  The present invention relates to a method of manufacturing a fiber reinforced plastic, in which a bag material is vacuum-sucked to press a reinforced fiber material against a mold, and more particularly, to manufacture a fiber reinforced plastic having a complicated shape in which the mold has a curved or bent shape. Regarding the method.

  In recent years, fiber reinforced plastic capable of reducing the weight of components has been widely used as a material due to increasing interest in global environmental problems. A method for producing a fiber reinforced plastic is a method in which a reinforcing fiber material is placed on a mold having a desired shape, and a matrix resin impregnated in the reinforcing fiber material is cured to integrate the reinforcing fiber and the matrix resin. Is common.

  As a method for producing fiber reinforced plastic, an RTM (Resin Transfer Molding) method or SMC (Sheet Molding Compound), in which a reinforcing fiber base material is press-pressed with upper and lower molds using a lower mold and an upper mold of a desired shape, and SMC (Sheet Molding Compound). Reinforced fiber material is placed on the lower mold of the desired shape and pressure molding method such as the method, the upper side of the reinforcing fiber material is covered with bag material such as film material, and the bag material inside is reinforced by vacuum suction There are bagging molding methods such as a prepreg method in which a fiber material is pressed against a mold and a VaRTM (Vacuum Resist Transfer Molding) method.

  The pressure molding method has an advantage that the dimensional accuracy is high and the smoothness of the surface of the molded product is excellent because the mold contacts both sides of the molded product. However, two high-precision molds, an upper mold and a lower mold, are required, and a press device for pressurization is required. Therefore, the facilities are large and complex, and the equipment costs are expensive. There was a demerit to be.

  On the other hand, the bagging molding method has an advantage that it can be manufactured only with the lower mold and that no large-scale equipment is required. However, since the bag material with flexibility hits the surface of the molded product, the bag material may be unevenly transferred along the surface of the molded product if it is in a form that is difficult to baggage. In some cases, it became difficult to achieve.

  In order to solve the above problem, a method using a pressing plate (sometimes called a simple upper die, a pressure plate, or a cowl plate) is known as in Patent Document 1. By using a pressing plate having a smooth surface and transferring the surface to the molded product, the surface smoothness of the molded product is improved. However, as in Patent Document 1, when applied to a flat plate, a plate-like pressing plate may be used. However, in order to apply to a complicated shape, the pressing plate is previously set in the same manner as the upper mold of the pressure molding method. It is necessary to process the product shape. For example, as shown in FIG. 1, when a convex mold is used, it is necessary to process the pressing plate into a product shape (in this example, an arc shape) in advance, and the reinforcing fiber base with the pressing plate fixed in shape. When pressing the flat surface portion, the flat portion is pressed first, so that the corner portion is wrinkled, and the strength of the fiber reinforced plastic may be lowered.

  Further, as disclosed in Patent Document 2, in the conventional VaRTM method, irregularities of a medium (also referred to as a resin diffusion medium) arranged for the purpose of resin diffusion in the surface direction may be transferred to a molded product. In order to eliminate the unevenness, the surface quality is improved by a method using a pass medium having a high bulk density (fine), but the transfer of the pass media pattern has not been completely removed. Further, as disclosed in Patent Document 3, in order to prevent the unevenness of the resin diffusion medium from being transferred to the molded product, it is exemplified that a porous sheet is applied between the preform on the flat plate and the resin diffusion medium. . However, like Patent Document 1, in order to make the porous sheet conform to a complicated shape, it is necessary to process the porous sheet in advance into a product shape in the same manner as the upper mold of the pressure molding method. Alternatively, a thin porous sheet may be used to make it easier to conform to the complex shape, but if the sheet is made thin enough to easily conform to the complex shape, the rigidity will be insufficient (after all, it will be at the same level as the bag material), and the surface It is conceivable that the smoothness does not improve.

JP 2003-048223 A Japanese Patent No. 3986426 Japanese Patent No. 4104422

  The present invention solves the problems of the prior art, and in the manufacturing method of fiber reinforced plastic using a mold and a bag material, even if the mold is a complicated shape having a curved or bent shape, the product shape is formed in advance. An object of the present invention is to provide a method for producing a fiber-reinforced plastic having a complex shape excellent in surface smoothness without preparing an upper mold or a pressing plate.

In order to solve the above problems, the method for producing a fiber-reinforced plastic according to the present invention takes the following means.
(1) A method for producing a fiber-reinforced plastic comprising the following steps (a) to (d):
(A) An arrangement step of arranging a molding material including a resin sheet material having smoothness equivalent to or higher than the surface roughness required for at least the reinforcing fiber base material and the final product on a curved or bent mold. (B) A shaping / heating step in which the molding material is pressed against the mold and shaped and heated (c) a curing step in which the matrix resin impregnated in the reinforcing fiber base is cured (d) a resin sheet Removal step of removing the material from the fiber reinforced plastic material (2) In the curing step (c), the matrix resin is heat-cured after injecting and impregnating the matrix resin into the dry reinforcing fiber base material. The manufacturing method of the fiber reinforced plastic as described in (1).
(3) The method for producing a fiber-reinforced plastic according to (1) or (2), wherein a plurality of through holes are perforated in the resin sheet material.
(4) The method for producing a fiber-reinforced plastic according to any one of (2) and (3), wherein the molding material is arranged in the order of a reinforced fiber base material, a resin sheet material, and a resin diffusion medium. .
(5) In the shaping / heating step (b), the molding material is covered with a bag material, and the bag material is vacuum-sucked to shape the molding material along the mold with the bag material, and then molded. The method for producing a fiber-reinforced plastic according to any one of (1) to (4), wherein the material is heated.
(6) In the curing step (c), the molding material including the dry reinforcing fiber base material is covered with a bag material, and the inside of the bag material is vacuum sucked to inject the matrix resin with a differential pressure. (2) The manufacturing method of the fiber reinforced plastic in any one of (5).
(7) The glass transition temperature (Tg) of the resin material constituting the resin sheet material is T1, and the heating temperature in the shaping / heating step (b) is (T1-20) ° C. or higher. The manufacturing method of the fiber reinforced plastic in any one of (1)-(6).
(8) The method for producing a fiber-reinforced plastic according to any one of (1) to (7), wherein a thickness of the resin sheet material is 0.1 mm or more and 1 mm or less.
(9) The method for producing a fiber-reinforced plastic according to any one of (1) to (8), wherein a resin material mainly composed of a thermoplastic resin is applied to the surface of the reinforcing fiber base.

  Even if the final product is a complicated shape having a curved or bent shape, it is possible to easily produce a fiber reinforced plastic having excellent surface smoothness without preparing an upper mold or a press plate formed in advance in the product shape. I can do it.

It is a schematic sectional drawing which shows the manufacturing method of the conventional fiber reinforced plastic. In the manufacturing method of the fiber reinforced plastic which concerns on this invention, it is a schematic sectional drawing which shows an arrangement | positioning process. In the manufacturing method of the fiber reinforced plastic which concerns on this invention, it is a schematic sectional drawing which shows a shaping and a heating process. In the manufacturing method of the fiber reinforced plastic which concerns on this invention, it is a schematic sectional drawing which shows a hardening process. In the manufacturing method of the fiber reinforced plastic which concerns on this invention, it is a schematic sectional drawing which shows a removal process. It is a schematic sectional drawing which shows the manufacturing method of the fiber reinforced plastic at the time of applying this invention to VaRTM method. It is a schematic sectional drawing which shows the manufacturing method of the fiber reinforced plastic at the time of applying this invention to another VaRTM method. It is the schematic which shows the resin-made sheet materials used for this invention. It is a schematic sectional drawing which shows embodiment of the shaping and heating process in the manufacturing method of the fiber reinforced plastic which concerns on this invention.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In addition, this invention is not limited to the specific aspect described in drawing.

  FIG. 2 is a cross-sectional view showing the flow of the fiber reinforced plastic manufacturing method according to the present invention. FIG. 3 is a cross-sectional view of a method for producing a fiber reinforced plastic when the present invention is applied to the VaRTM method.

  One embodiment of the present invention is a method for producing a fiber reinforced plastic using a mold 1 and a bag material 5, as shown in FIG. 2, at least on the mold 1 having a desired shape having a curved or bent shape. A molding material 31 including the reinforcing fiber base 2 and the resin sheet material 4 is arranged (arrangement step). Thereafter, the molding material 31 is covered with the bag material 5 and the periphery is sealed with the sealing 6. The inside of the bag material 5 is vacuum-sucked with the vacuum pump 7 to press the molding material 31 against the mold 1 to form the molding material. 31 is heated (shaped heating process). Thereafter, the matrix resin impregnated in the reinforcing fiber base is cured (curing process), and finally the resin sheet material is removed from the cured fiber reinforced plastic material 9 (removing process).

  The present invention is suitable when the final product has a complicated shape, and the mold 1 has a curved surface or a bent shape. Specifically, the curved surface or the bent shape according to the present invention refers to a shape having a curved surface other than a flat surface at least partially, or a shape bent in at least two plane directions intersecting each other.

  Hereinafter, the present invention will be described in detail in the order of each step.

(A) Arrangement Step As shown in FIG. 2, a molding material including at least a reinforcing fiber base material and a resin sheet material is arranged on a convex mold having an arcuate curved corner portion 8.

  The reinforcing fiber base material may be a sheet-like prepreg material in which a resin is impregnated in advance with a reinforcing fiber, or may be a dry woven or knitted reinforcing fiber base material not impregnated with a resin. . In the case of a dry reinforced fiber base material, the shape of the reinforced fiber base material is fixed after the shaping heating process that a resin material mainly composed of a thermoplastic resin is applied to the surface of the base material. This is preferable.

  Resin sheet material is made of resin and can easily conform to the shape of the mold during shaping. Then, after cooling, the shape can be fixed as it is. In addition, by using a resin sheet material having a smoothness equal to or greater than the surface roughness required for the final product, the surface of the sheet material is transferred to a molded product to obtain a fiber reinforced plastic excellent in desired surface properties. I can do it. The surface roughness in this invention means the size of the surface asperity defined by JIS0601-1976 standard. The smoothness equal to or higher than the same means that the final product is the same or smoother, that is, the surface roughness Ra and Rmax are the same or smaller.

  The material of the resin sheet material may be a thermoplastic resin or a thermosetting resin. Specifically, polyester resin, nylon resin, polyethylene resin, polypropylene resin, polyphenylene sulfide (PPS) resin, or the like may be used. The thickness of the sheet material is preferably 0.1 mm or more in order to maintain the surface smoothness, and preferably 1 mm or less in order to easily follow the shape during shaping.

  In the removing step (d), in order to easily peel the resin sheet material, a liquid release agent may be applied to the resin sheet material, or between the resin sheet material and the reinforcing fiber substrate. Further, a peeling woven fabric called a peel ply may be arranged. As the release agent, for example, a liquid organic solvent to which a silicon-based peeling component is added can be used, and as the peel ply, for example, nylon or polyester taffeta can be used.

(B) Molding / heating step Thereafter, the molding material is pressed against the mold to be shaped, heated, and molded into a desired shape.

  FIG. 6 is a schematic cross-sectional view showing an example of an embodiment of a shaping / heating step in the method for producing a fiber-reinforced plastic of the present invention. Although there is no particular limitation on the method of fitting along the mold, as shown in FIG. 6A, the pressure roller is raised from the upper surface portion 65 of the mold while pressing the molding material 31 against the mold 1 with the pressure roller 61. The molding material may be shaped along the mold while moving in the direction 62 of the surface portion 66, or the molding material 31 may be molded with the press load 64 of the press mold 63 as shown in FIG. You may press to 1 and shape. When using a press, it is preferable that the corner portion and the flat plate portion are divided from the viewpoint of preventing wrinkles, and the upper surface portion 65, the corner portion, and the standing surface portion 66 are pressed in this order. Further, as shown in FIG. 2 (b), the molding material is covered with a bag material, and the inside of the bag material is vacuum-sucked so that the reinforcing fiber base material is pressed along the lower mold while being shaped. It can also be heated. The bag material can follow the shape of the mold and is not particularly limited as long as it is an impermeable sheet, but a resin film or a rubber-like sheet can be used. As the resin film, for example, a nylon film having a thickness of less than 0.1 mm, a silicon rubber sheet, or the like can be used. In terms of shaping along the mold using a bag material, it is particularly suitable for a mold having a convex shape.

  As shown in FIG. 1, when the mold 1 is a convex type, if the pre-shaped pressing plate 3 is used as in the prior art, the flat portion 21 is pressed first, so that the corner portion is strengthened. Wrinkles 22 may occur in the fiber base material, and the occurrence of such wrinkles may lead to a decrease in strength of the component. On the other hand, in the present invention, as shown in FIG. 3, since the molding material is pressed in order from the upper surface to the lower surface of the mold, the reinforcing fiber base material and the resin sheet material are not wrinkled along the convex mold at the same time. Shaped. According to the present invention, wrinkles at corners can be suppressed, so that the problem of reduced strength of parts can be solved.

  The resin sheet material can be softened by, for example, heating with hot air 23 as shown in FIG. 2B and can easily conform to the shape of the mold. The timing of heating may be heated after shaping according to the complexity of the shape of the mold, or may be shaped simultaneously while heating. Further, as shown in FIG. 6, when the roller 61 or the press die 63 is used, the shaping and the heating can be performed simultaneously by heating the roller or the press die itself. When forming at the same time while heating, it is possible to easily conform to the shape of the mold while the resin sheet material is softened. If the resin sheet material is cooled and hardened after this step, the resin sheet material can be fixed in shape while keeping the desired shape.

  As described above, one feature of the present invention is that a resin sheet material is used to conform to a complicated shape by heating. For example, when a metallic sheet material is used, there is a problem that it is difficult to follow a complicated shape because the material is hard and hardly stretched. Furthermore, when the deformation of the sheet material is in the elastic region, there is a problem that the shape returns to the sheet shape when the vacuum degree inside the bag material is lowered, while on the other hand, a considerable load is required to deform to the plastic region. It cannot be realized with simple equipment as in the invention. The present invention makes use of the softness of the resin sheet to maintain the surface properties of the sheet material, conform to a complex shape, and further heat and soften to fully fit the mold shape. It is possible to make it.

  Here, when the glass transition temperature (Tg) of the resin material constituting the resin sheet material is T1, the heating temperature in the shaping / heating step (b) is preferably (T1-20) ° C. or higher. More preferably, it is T1 or more. By setting the heating temperature in the vicinity of the glass transition temperature (Tg) of (T1-20) ° C. or higher, the resin sheet is easily removed from the elastic region, so that it easily follows the shape of the mold and has a predetermined shape when cooled. Can be fixed. If the melting point is not exceeded, the sheet state is maintained, so that the smooth state of the sheet surface is maintained, and the surface smoothness of the fiber reinforced plastic can be maintained. The glass transition temperature (Tg) can be measured by, for example, a DSC method or a DMA method.

  In the case of a particularly complicated shape in which the shape of the mold changes three-dimensionally, the resin sheet material may be appropriately cut to prevent wrinkles.

(C) Curing step When the reinforcing fiber substrate is a prepreg impregnated with a resin in advance, a matrix resin impregnated in the reinforcing fiber substrate is applied in an autoclave capable of being heated and pressurized after the shaping heating step. Heat cure.

  FIG. 4 is a schematic cross-sectional view showing a method for producing a fiber reinforced plastic when the present invention is applied to another VaRTM method. FIG. 5 is a schematic view showing a resin sheet material used in the present invention.

  Further, as shown in FIG. 4, the present invention is also suitable for the VaRTM method in which the matrix resin 11 is injected and impregnated into a dry reinforcing fiber base material before the heat curing of the matrix resin. As the dry reinforcing fiber substrate, for example, a woven fabric or a knitted fabric using carbon fibers, glass fibers or the like as reinforcing fibers can be used. In the VaRTM method, it is preferable to use the resin diffusion medium 10 in order to quickly diffuse the resin in the surface direction. The resin diffusion medium 10 is not particularly limited as long as it is a sheet having a void serving as a resin flow path, but a mesh material, a fiber fabric, or the like can be used. However, when used as a resin diffusion medium, there is a problem that the pattern is transferred to the surface of the molded product and the design of the product surface is lowered. In order to solve the problem, it is preferable that the molding material is arranged in the order of the reinforcing fiber base material, the resin sheet material, and the resin diffusion medium.

  Further, as shown in FIG. 5, it is preferable that a plurality of through holes 12 are formed in the resin sheet material. By perforating a plurality of through holes in the sheet material, the resin diffused in the resin diffusion medium can permeate the reinforcing fiber substrate through the through holes. Further, if the through hole has a small diameter of, for example, 3 mm or less, the surface smoothness of the molded product can be maintained.

  The resin curing temperature may be set as appropriate according to the type of matrix resin to be used, but is preferably set below the melting point of the resin material constituting the sheet material.

  After the shaping / heating step, the molding material may be cooled and moved to another mold, and then the matrix resin impregnated in the reinforcing fiber base may be heat-cured. If the molding material is cooled, the resin sheet material becomes hard, so that the shape is fixed and moved along the desired shape. In that case, only the resin sheet material can be separated and carried.

(D) Removal step Finally, by removing the resin sheet from the molding material in which the matrix resin is cured, a fiber reinforced plastic having excellent surface smoothness can be obtained. The removed resin sheet may be reused.

  The obtained fiber reinforced plastic has a desired shape along a complicated mold shape, and is excellent in surface smoothness transferred from the smooth surface of the resin sheet material. In addition, since the resin sheet material is firmly in line with the mold shape, there is no problem such as wrinkles of reinforcing fibers in the cross section of the corner portion, and a product with good quality without strength reduction can be obtained.

  As described above, according to the method for producing a fiber reinforced plastic according to the present invention, without preparing a pressing plate having a desired shape, a resin sheet material is simply arranged and heated, and is excellent in quality. Fiber reinforced plastic can be obtained.

As shown in FIG. 2, a molding material comprising a reinforcing fiber base 2 and a resin sheet 4 which are cut according to the size of a product on a steel mold 1 having a ¼ arc section with a radius of 5 mm. 31 was placed. The reinforcing fiber base 2 is a unidirectional carbon fiber woven fabric obtained by dispersing and imparting a thermoplastic resin to a unidirectional woven fabric (weight per unit area 190 g / m ² ) of carbon fiber T800S (PAN-based carbon fiber, 24,000 filaments) manufactured by Toray Industries, Inc. (Toray Industries, Inc., product name CZ8433DP) was produced by stacking 24 sheets. In addition, as a resin sheet material, a polyester film “Lumirror (registered trademark)” 350S10 (surface roughness of 25S or less) manufactured by Toray Industries, Inc. was used. The resin sheet material was perforated with through holes having a hole diameter of 0.5 mm and a hole pitch of 5 mm for passing through the matrix resin.

  A bag material 5 made of a silicon rubber sheet having a thickness of 2 mm was placed on the molding material and vacuum-sucked, and the molding material was shaped while being pressed against the shape of the mold 1. Then, it put in oven and heated with hot air 23 at 80 degreeC for 1 hour, and cooled to room temperature. As a result of removing the rubber sheet after cooling, it was confirmed that the reinforcing fiber base material and the resin sheet material were shaped following the shape of the mold.

  Next, as shown in FIG. 4, the resin diffusion medium 10 made of Tokyo Netron TSX-400P is placed on the resin sheet material 4 and communicated with the matrix resin 11 to make a bag made of RICHMOND HS-800. The bag was covered with the material, and the inside of the bag material was decompressed to 0.1 kPa by the vacuum pump 7. The matrix resin 11 made of the epoxy resin TR-A37 manufactured by Toray Industries, Inc. was diffused in the surface direction by the resin diffusion medium 10 by the vacuum suction force and permeated inside the reinforcing fiber base. After the matrix resin penetrated the entire reinforcing fiber substrate, the mold was heated to 120 ° C. and held for 5 hours to cure the matrix resin.

  Thereafter, as shown in FIG. 2 (d), the resin sheet material was removed together with the resin diffusion medium (not shown) to obtain a fiber reinforced plastic material 9.

  As a result of confirming the quality of the fiber reinforced plastic, both the side surface of the mold and the side surface of the bag were finished to the desired dimensions along the mold, and the surface roughness of the bag side surface was in a favorable state of 25S or less. Moreover, as a result of cutting the fiber-reinforced plastic and observing the cross section, it was confirmed that the internal reinforcing fiber was free of significant wrinkles. As described above, according to the present invention, a reinforced fiber plastic having good quality could be obtained.

  INDUSTRIAL APPLICABILITY The present invention can be applied to any method for producing reinforced fiber plastics, and is particularly suitable for producing a member having a complicated shape that requires surface smoothness, for example, a vehicle, a ship, an aircraft, a building member, etc. The present invention can be applied to a wide range of fiber-reinforced plastic manufacturing methods used in various fields such as industrial use or sports use.

1: Mold 2: Reinforced fiber base material 3: Press plate 4: Resin sheet 5: Bag material 6: Sealing 7: Vacuum pump 8: Corner portion 9: Fiber reinforced plastic material 10: Resin diffusion medium 11: Matrix resin 12 : Through hole 21: Flat surface portion 22: Wrinkle 23: Hot air 31: Molding material 61: Pressure roller 62: Moving direction of roller 63: Press mold 64: Press load 65: Upper surface portion 66: Standing surface portion

Claims (9)

The manufacturing method of the fiber reinforced plastic characterized by including the process of the following (a)-(d).
(A) An arrangement step of arranging a molding material including a resin sheet material having smoothness equivalent to or higher than the surface roughness required for at least the reinforcing fiber base material and the final product on a curved or bent mold. (B) A shaping / heating step in which the molding material is pressed against the mold and shaped and heated (c) a curing step in which the matrix resin impregnated in the reinforcing fiber base is cured (d) a resin sheet Removal process to remove material from fiber reinforced plastic material The method for producing a fiber-reinforced plastic according to claim 1, wherein, in the curing step (c), after the matrix resin is injected and impregnated into the dry reinforcing fiber base material, the matrix resin is heated and cured. The method for producing a fiber reinforced plastic according to claim 1, wherein a plurality of through holes are formed in the resin sheet material. The method for producing a fiber-reinforced plastic according to claim 2, wherein the molding material is arranged in the order of a reinforcing fiber base, a resin sheet material, and a resin diffusion medium. In the shaping / heating step (b), the molding material is covered with a bag material, and the bag material is vacuumed to shape the molding material along the mold with the bag material, and the molding material is heated. The manufacturing method of the fiber reinforced plastic in any one of Claims 1-4 characterized by the above-mentioned. 3. In the curing step (c), a molding material containing a dry reinforcing fiber base is covered with a bag material, and the inside of the bag material is vacuum sucked to inject a matrix resin with a differential pressure. The manufacturing method of the fiber reinforced plastic in any one of -5. The glass transition temperature (Tg) of the resin material constituting the resin sheet material is T1, and the heating temperature in the shaping / heating step (b) is (T1-20) ° C. or more. Item 7. A method for producing a fiber-reinforced plastic according to any one of Items 1 to 6. The method for producing a fiber-reinforced plastic according to any one of claims 1 to 7, wherein a thickness of the resin sheet material is 0.1 mm or more and 1 mm or less. The method for producing a fiber reinforced plastic according to any one of claims 1 to 8, wherein a resin material mainly composed of a thermoplastic resin is applied to a surface of the reinforced fiber base material.

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