JP2012196861A - Method for manufacturing hollow fiber reinforced plastic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing desired hollow fiber reinforced plastic which can manufacture a light-weight core at high accuracy and high rigidity, does not cause a trouble such as the intrusion of resin into the core, can easily take out even a core inner member after molding, can easily reuse the taken-out inner member, and can surely and efficiently manufacturing the desired hollow fiber reinforced plastic.SOLUTION: The method for manufacturing the hollow fiber reinforced plastic is characterized in that: a block body is formed by coupling solid particles by using a water soluble adhesive; the core is manufactured by covering the block body with a resin impermeable film; the fiber reinforced plastic is formed around the core by using the core; and the fiber reinforced plastic molded with the solid particles in the core is discharged to the outside by releasing the coupling by the water soluble adhesive after molding.

Description

  The present invention relates to a method for producing a hollow fiber reinforced plastic, and more particularly to a method for producing a hollow fiber reinforced plastic in which a hollow portion is formed using a special core.

  Conventionally, various molding methods are known in which a hollow portion is molded using a core. For example, Patent Document 1 discloses a method for forming a hollow fiber reinforced plastic structure using a blow molding core made of a resin that can be expanded and contracted. However, the resin core has a problem that the linear expansion is large and the variation in the expansion amount due to heating is large. In blow molding, the hollow core made of resin is inflated to fit along the mold. Therefore, the core needs to be at least 2 mm thick due to the problem of tearing. It is difficult to fit a mold having a complicated shape.

  Patent Document 2 discloses a method for molding a fiber-reinforced plastic hollow molded article in which a synthetic wax is melted and removed after molding using a synthetic wax hollow core. However, synthetic waxes have a problem that linear expansion and volume expansion between a solid and a liquid are large, and a variation in expansion amount is large. Further, since the rigidity is low, the core easily deforms.

  In Patent Document 3, gypsum is cured to produce a hollow core, a carbon fiber reinforced resin sheet is pasted around the core and melt-cured, and then the gypsum inside is dissolved and taken out. A method for producing a hollow molded article made of carbon fiber reinforced plastic is disclosed. However, since plaster is dense, there is a problem that the solution does not penetrate and is difficult to dissolve and take out.

  Patent Document 4 discloses a method for molding a gas fuel tank in which a fiber reinforced resin is molded around a hollow core of a low melting point alloy and then the core made of the low melting point alloy is eluted. However, repeated melting and solidification causes separation of the low melting point alloy, which leaves a problem in recyclability.

  Patent Document 5 discloses a sand mold member using coated sand particles for casting and a method for manufacturing the same. However, in the case of a material that hardens as soon as it comes into contact with the mold member, such as a casting, the penetration of the molten metal into the mold member can be suppressed. However, the resin itself requires heating of the mold itself, and the low viscosity time of the resin is long. The resin completely penetrates into the mold member, and the lost core after molding becomes impossible. Therefore, this method cannot be applied to molding of hollow fiber reinforced plastic.

  Patent Document 6 discloses a method for producing a fiber-reinforced plastic hollow molded article using a core formed by mixing a solvent-soluble thermoplastic resin and foundry sand. However, in this method, a film is formed on the surface of the core, but the resin penetrates into the core and hardens. Therefore, there is a problem that it is difficult to take out a portion where sand and resin are integrated.

  Patent Document 7 discloses that a core is formed by friction-engaging sand by vacuum suction from the inside of a hollow bag filled with sand, and between the core and an outer mold that covers the core. Discloses a method for forming a hollow container made of fiber reinforced plastic into which uncured resin is injected. However, this method has a problem that the size of the core is highly likely to vary because the volume that changes during vacuum suction cannot be read.

  Patent Document 8 discloses a preform (core) in which a core made of a water-soluble block material is covered with a curable polymer, the polymer is cured, and then the core material is removed using water. A manufacturing method is disclosed. However, in this method, at the stage of covering the core with the polymer before curing, there is a problem that the polymer penetrates into the core not a little, and the core material cannot be removed properly after the polymer is cured.

  Further, Patent Document 9 discloses a method using a foamed resin core core covered with a non-adhesive nylon film. However, with this method, a lost core after molding is not possible, and this method is applicable only when a foamed resin core is incorporated in a molded product.

  As described above, in the conventional method, a method for producing a core for manufacturing a hollow fiber reinforced plastic with high accuracy and little variation has not been found, and the core inner member can be easily taken out after forming the hollow fiber reinforced plastic. No technique has been found that can be removed.

JP 2006-159457 A JP 2007-307853 A JP 2002-36381 A JP-A-9-323365 Japanese Patent No. 2787022 Japanese Patent Laid-Open No. 4-200838 JP 59-49931 A JP-T-2004-520972 Japanese Patent No. 4529371

  Therefore, in view of the current situation as described above, the problem of the present invention is that cores of various shapes can be manufactured with high accuracy, high rigidity, and light weight without causing the problem of resin penetration into the core. An object of the present invention is to provide a method in which a core inner member can be easily taken out after molding, the taken out inner member can be easily reused, and a desired hollow fiber reinforced plastic can be reliably and efficiently manufactured.

  In order to solve the above-mentioned problems, the method for producing a hollow fiber reinforced plastic according to the present invention forms a block body by bonding solid particles with a water-soluble adhesive, and the block body is made of a resin-impermeable membrane. A core is manufactured by covering, and a fiber reinforced plastic is molded around the core using the core, and after molding, the solid particles in the core are released by releasing the bond with the water-soluble adhesive. The method comprises discharging the molded fiber reinforced plastic to the outside.

  In such a method for producing a hollow fiber reinforced plastic according to the present invention, a block body is formed by bonding solid particles with a water-soluble adhesive, but a block having a desired shape is formed by bonding relatively fine particles. Since the body is formed, the block body can be formed in a desired shape with high accuracy. Further, since solid particles having relatively high strength and rigidity of individual particles are combined to form a block body, the formed block body as a whole can have relatively high strength and rigidity. The water-soluble adhesive is not given so as to completely fill the voids between the solid particles, but the solid particles are bonded together by the water-soluble adhesive while leaving a relatively large amount of voids inside the block body. To form a block body. The block body formed in this manner is covered with a resin-impermeable film, whereby a core is produced. This membrane can be thin as long as it is impermeable to resin, and can be easily formed with high accuracy in the desired shape along the shape of the block body, either as the entire core, or in particular, as the outer shape of the core. In addition, relatively high strength and rigidity based on the strength and rigidity of the block body can be imparted to the entire core. Using this core, fiber reinforced plastic is molded around the core. The molding method is not particularly limited, but in any molding method, the matrix resin melted by heating exists around the core, but the core is covered with a resin-impermeable film. Therefore, the resin does not penetrate into the membrane itself or the core. Therefore, the target molding is performed without causing the problem of resin penetration into the core. Then, after the resin is cured and the molding is completed, the binding by the water-soluble adhesive is released, and the solid particles in the core are discharged to the outside of the molded fiber reinforced plastic. Since the bonding is performed with a water-soluble adhesive, the bonding is easily released with water or the like without using an organic solvent or the like. When solid particles are discharged from the core, the portion where the molded fiber-reinforced plastic core was present is basically formed in a hollow shape, and a desired hollow fiber-reinforced plastic is produced. The resin impervious membrane is basically left in the hollow portion, but it is sufficient to use a thin membrane as described above, which is large in the characteristics and weight of the molded hollow fiber reinforced plastic. There is no effect.

In the method for producing a hollow fiber reinforced plastic according to the present invention, it is particularly preferable to use a plastic film as the resin-impermeable membrane. By using an appropriate plastic film, the resin impermeability can be surely satisfied, and this can be achieved with a thin film. In addition, since the plastic film can be easily inspected for defects, the resin impermeability can be reliably satisfied. Furthermore, by using a thin plastic film, it can be easily and accurately arranged along the outer shape of the block body.

  In particular, when a heat-shrinkable film is used as the plastic film, the film can be easily and accurately conformed to the outer shape of the block body simply by heating. In this case, it is possible to easily and accurately follow the block body by heat shrinking the heat shrink film in a state where the block body is included in the heat shrink film.

  Further, when the block body has a recess (concept including a concave corner portion in addition to the groove-shaped recess), the block body is included in the heat shrinkable film in a state of being included. When placing a pedestal on the recess from the outside of the heat shrink film, heat shrinking the heat shrink film, and removing the lay insert when the temperature becomes lower than the heat shrink temperature, The film can be easily and accurately applied.

  The molding method for molding the fiber-reinforced plastic in the present invention is not particularly limited, but the present invention is particularly effective when performing RTM molding (Resin Transfer Molding). That is, it has been considered that it is relatively difficult to form a hollow part easily and accurately in RTM molding. However, by applying the present invention, a desired hollow part can be easily formed.

  Further, in the present invention, since a water-soluble adhesive is used for bonding solid particles, the bonding is easily released with an aqueous solvent (for example, water, warm water, or a hydrophilic solvent) without using an organic solvent or the like. It becomes possible. That is, by injecting an aqueous solvent into the core, the solid particles are released from bonding with the water-soluble adhesive, and the released solid particles are discharged together with the aqueous solvent to the outside of the molded fiber reinforced plastic. You just have to do it. As for the injection of the aqueous solvent, for example, a small hole leading to the inside of the core may be made in the molded fiber reinforced plastic and injected from there, and in order to discharge the solid particles together with the aqueous solvent, the solid particles pass in the same way. What is necessary is just to make a small hole possible and to discharge | emit using the said injection pressure.

  Moreover, in this invention, it is preferable to use the particle | grains which can be reused after discharge | emission from the shape | molded fiber reinforced plastic as said solid particle. Therefore, particles of a material that is deformed or altered by heating for molding are not preferable, and it is preferable to use, for example, sand whose particle size is controlled as solid particles. Since the solid particles can be reused, the same molding can be repeatedly performed with substantially the same operation, and the productivity can be improved. If the water-soluble adhesive remains in the discharged solid particles, it can be reused by simply drying it. It becomes possible to use. In addition, by using sand whose particle size is controlled, it becomes possible to form a block body with high accuracy even in a complicated shape, and consequently, a core and a hollow part can be formed with high accuracy. It becomes possible.

  In addition, it does not specifically limit as a use reinforcement fiber of the hollow fiber reinforced plastics in this invention, The reinforcement fiber of the hybrid structure which combined these with carbon fiber, glass fiber, an aramid fiber, and these can be used. Further, the matrix resin is not particularly limited, and any of a thermosetting resin, a thermoplastic resin, and a combination of these can be used.

  As described above, according to the method for producing a hollow fiber reinforced plastic according to the present invention, the block body is formed by bonding the solid particles with the water-soluble pressure-sensitive adhesive, so that the cores having various shapes according to the request can be accurately obtained. In addition, it can be manufactured with high rigidity and light weight. In addition, by covering the block with a resin-impermeable film, the core can achieve impermeability with respect to both the surface coating material for forming the core and the resin for molding. The occurrence of the resin penetration problem can be prevented, and solid particles can be easily taken out from the core after molding. If a plastic film, especially a thin film, more preferably a heat-shrinkable film is used as the resin-impermeable membrane, the core can be made more precise, rigid and lightweight even with relatively complex shapes. Can be produced. Moreover, since the amount of voids in the core can be set large, it can be formed into a light core and is extremely excellent in handleability. In addition, since a water-soluble adhesive is used to bond the solid particles forming the block body, the solid particles can be easily released with an aqueous solvent and discharged to the outside without using an organic solvent. Can be facilitated and the working environment is also excellent. Furthermore, coupled with the ease of discharge and the impermeability of the resin into the core, the extracted solid particles can be easily reused. As a result, a desired hollow fiber reinforced plastic can be manufactured reliably and efficiently with high productivity.

It is a process flow figure showing an example of the manufacture process of the core in the manufacturing method of the hollow fiber reinforced plastic concerning one embodiment of the present invention. It is a process flow figure showing an example of a process which manufactures hollow fiber reinforced plastic using a core created by a process of Drawing 1. For comparison with the present invention, it is a schematic cross-sectional view of a core portion showing a defect occurrence example when a block body made of a granular material is coated with a low-viscosity thin film. For comparison with the present invention, it is a schematic cross-sectional view of a core portion showing an example of defect occurrence when a highly viscous film is coated on a block body made of a granular material. For comparison with the present invention, it is a schematic cross-sectional view of a core portion showing a defect occurrence example in blow core pressure forming. For comparison with the present invention, it is a schematic cross-sectional view of a stretched material portion showing an example of a defect occurrence in the case of stretched material internal pressure molding.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an example of a core manufacturing process in a method for manufacturing a hollow fiber reinforced plastic according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes fine solid particles (for example, sand whose particle size is controlled to a predetermined average particle size), and a large number of solid particles 1 are formed from, for example, a heat-shrinkable plastic film (heat-shrinkable film). Are formed into a block body 3 having a predetermined shape by bonding with a water-soluble adhesive on the lower resin-impermeable membrane 2 made of

  The formed block body 3 is covered with an upper resin-impermeable film 4 made of, for example, a heat-shrinkable plastic film (heat-shrinkable film), and the upper film 4 is formed by the indenter 6 along the seal line 5. It joins with the lower film | membrane 2 (joining integration part 7). For this bonding, an adhesive may be used, or the bonding may be integrated by heat fusion. By this joining, the whole block body 3 is covered from the periphery by the resin-impermeable membranes 2 and 4 (heat-shrink film). After covering with a resin impervious film (heat-shrinkable film), in a state where the block body 3 is encapsulated in the resin impervious films 2 and 4 (heat-shrinkable film), a concave corner portion as the concave portion 8 of the block body 3 The holder 9 is disposed from the outside of the upper film 4 at a position corresponding to the above.

  From the above state, the film part outside the joint integrated part 7 is removed (trim part 10), and then the resin impervious films 2 and 4 (heat-shrinkable film) are heated by the heater 11 to heat-shrink film. 2 and 4 are heat-shrinked so as to be in close contact with the outer shape of the block body 3 including the joint integrated part 7, and the core 12 including the block body 3 is manufactured. The holder 9 may be removed at the time of heat shrinkage of the heat shrink films 2 and 4 or after heat shrinkage (when the temperature becomes lower than the heat shrink temperature).

  As shown in FIG. 2, the core 12 formed in this way has a block 3 made of solid particles 1 and a resin impermeable membrane 13 made of the resin impermeable membranes 2 and 4 from its periphery. The core 12 is used for the production of hollow fiber reinforced plastic. For example, as shown in FIG. 2, first, a core preform (hereinafter, the preform may be abbreviated as PF) 14 made of a reinforcing fiber base is disposed on the upper surface side of the core 12. In this state, after being placed at a predetermined position on the skin preform (skin PF) 16 disposed on the lower mold 15 made of a mold, the upper mold 17 is clamped. A temperature control line 18 is passed through the lower mold 15 and the upper mold 17 and each is heated to a predetermined temperature. Further, the upper mold 17 is provided with a resin flow path 19, and the resin is injected into the cavity formed between the lower mold 15 and the upper mold 17 through the resin flow path 19. The core PF14 and skin PF16 are impregnated with the resin. When the resin impregnated by heating is polymerized, cross-linked, and demolded, a fiber reinforced plastic molded product 21 having a core inclusion 20 is produced.

  Next, the discharge of solid particles and the production of a hollow molded product are performed, for example, as follows. In the illustrated example, a small injection hole 23 is opened at one end of the core inner portion 20 with a drill 22 and a discharge hole 24 is opened at the other end of the core 21 of the molded product 21. The molded product 21 is supported on the support 26 in the water tank 25, and water (or hot water) as an aqueous solvent passes through the tube 27 and enters the core containing portion 20 from the injection hole 23 with a predetermined water flow 28. It is injected toward the block body 3. By the injection of water as the aqueous solvent, the binding by the water-soluble adhesive that has bound the solid particles 1 to each other is released, the form of the block body 3 is destroyed, and the solid particles 1 in the core 12 are brought together with water. The product is discharged from the discharge hole 24 to the outside of the molded product 21. At this time, most of the solid particles 1 discharged into the water tank 25 are discharged in a state where the water-soluble adhesive remains attached. Therefore, the discharged solid particles 29 can be reused only by drying.

  The molded product from which the solid particles 1 are discharged becomes a hollow molded product 31 in which the cavity 30 defined by the resin impervious film 13 is formed in the core inclusion 20. The injection hole 23 and the discharge hole 24 which are small holes remain, but if there is no problem, they may be left as they are. If it is preferable to close the hole, it may be closed with a repair resin or the like.

  According to the method as described above, the block 12 is formed by bonding the solid particles 1 with a water-soluble pressure-sensitive adhesive in a state in which an appropriate gap is left, so that the core 12 having various shapes can be formed with high accuracy and high accuracy. It can be made rigid and lightweight, and by covering the block body 3 with a resin-impermeable membrane 13, it is possible to prevent problems associated with resin penetration and to easily take out the solid particles 1 from the core after molding. Is possible. Further, since a thin plastic film, particularly a heat shrink film, is used as the resin-impermeable film 13, the core can be easily produced with high accuracy even if it has a relatively complicated shape. In addition, since a water-soluble adhesive is used for bonding the solid particles 1, it is not necessary to use an organic solvent, and the solid particles 1 can be easily released by being injected into the core of an aqueous solvent and discharged to the outside. become able to. Furthermore, the solid particles 1 taken out can be reused almost completely.

Various comparative examples are illustrated for comparison with the present invention that exhibits the excellent effects as described above.
FIG. 3 shows an example of the occurrence of defects when the core 104 is produced by coating the block body 102 made of the granular body 101 with the low-viscosity thin film 103. The low-viscosity thin film 103 is likely to have film defects 105 such as perforations, and the low-viscosity thin film 103 is likely to penetrate into the block body 102 (penetration portion 106). Further, in the molding of the molded product 107, the molding resin easily penetrates into the core 104 from the film defect 105 or the like (resin permeation portion 108), and the low-viscosity thin film 103 that has penetrated into the block body 102 is formed. For this reason, it becomes difficult to discharge all of the granular material 101 from the core 104, and a residual granular material 109 is generated in the core. As a result, the weight of the molded product 107 increases.

  FIG. 4 shows an example of the occurrence of defects when the core 114 is produced by coating the block body 112 made of the granular material 111 with the high-viscosity film 113. The film thickness 115 of the high-viscosity film 113 tends to be thick. Therefore, the molding resin of the molded product 116 is less likely to penetrate into the core 114 and the remaining granular material 117 is reduced. However, since the film thickness of the remaining high-viscosity film 113 is large, the weight of the hollow molded article 116 increases.

  FIG. 5 shows a defect occurrence example in the case of blow core internal pressure molding in which the molded article 123 is molded by applying an internal pressure 122 to the blow core 121. In the case of blow core internal pressure molding, the thickness of the blow core 121 is relatively large. In particular, the flat portion that stretches is formed in the thick portion 125 to prevent loss compared to the thin portion 124 such as a corner portion. Yes. Since such a relatively thick blow core 121 is contained after molding, the weight of the hollow molded article 123 increases.

  FIG. 6 shows an example of the occurrence of defects in the case of stretched material internal pressure molding in which the molded product 133 is molded by applying the internal pressure 132 to the stretched material 131. In the case of stretch material internal pressure molding, the stretch material 131 can be made relatively thin, but it is difficult to press at the corner portion, and the resin-rich portion 134 of the molded product 133 is likely to occur at that portion.

  The method for producing a hollow fiber reinforced plastic according to the present invention is applicable to any molding in which a hollow portion is molded using a core, and is particularly suitable when a hollow molded product is molded by RTM molding.

DESCRIPTION OF SYMBOLS 1 Solid particle 2, 4, 13 Resin impermeable membrane 3 Block body 5 Seal line 6 Indenter 7 Joint integrated part 8 Recess 9 Placement 10 Trim part 11 Heater 12 Core 14 Core preform 15 Lower mold 16 Skin Reform 17 Upper mold 18 Temperature control line 19 Resin flow path 20 Core inclusion 21 Fiber reinforced plastic molded product 22 Drill 23 Injection hole 24 Discharge hole 25 Water tank 26 Support body 27 Tube 28 Water flow 29 Discharged solid particles 30 Cavity 31 Hollow Molding

Claims (9)

  A block body is formed by binding solid particles with a water-soluble adhesive, and a core is produced by covering the block body with a resin-impermeable membrane, and the core is used around the core. A hollow fiber reinforced plastic, characterized in that a fiber reinforced plastic is molded, and after molding, the binding by the water-soluble adhesive is released and solid particles in the core are discharged to the outside of the molded fiber reinforced plastic. Manufacturing method.   The method for producing a hollow fiber reinforced plastic according to claim 1, wherein a plastic film is used as the film.   The method for producing a hollow fiber reinforced plastic according to claim 2, wherein a heat shrink film is used as the plastic film.   The method for producing a hollow fiber reinforced plastic according to claim 3, wherein the heat shrinkable film is heat shrunk in a state in which the block body is included in the heat shrinkable film so as to be along the block body.   The block body has a recess, and an insert is disposed on the recess from the outside of the heat shrinkable film with the block body enclosed in the heat shrinkable film, and the heat shrinkable film is heat shrunk. The manufacturing method of the hollow fiber reinforced plastics of Claim 4 which removes the said nest at the time of becoming below heat shrink temperature.   The method for producing a hollow fiber reinforced plastic according to any one of claims 1 to 5, wherein the fiber reinforced plastic is molded by RTM molding.   By injecting an aqueous solvent into the core, the solid particles are unbound by the water-soluble pressure-sensitive adhesive, and the solid particles after the release are discharged to the outside of the molded fiber reinforced plastic together with the aqueous solvent. The manufacturing method of the hollow fiber reinforced plastic in any one of Claims 1-6.   The manufacturing method of the hollow fiber reinforced plastics in any one of Claims 1-7 using the particle | grains which can be reused after discharge | emission from the shape | molded fiber reinforced plastics as said solid particles.   The method for producing a hollow fiber reinforced plastic according to any one of claims 1 to 8, wherein sand having a controlled particle size is used as the solid particles.

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