JP2008246675A - Inner pressure molding method of frp hollow molded product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inner pressure molding method for easily obtaining an FRP hollow molded product having beautiful appearance. <P>SOLUTION: When the FRP hollow molded product is molded by the inner pressure molding method using a prepreg, first a prepreg other than a prepreg for forming the surface layer part of the resin molded product is laid and laminated on the shaping mold of the resin molded product to form a shaped article having an inner pressure bag therein. Subsequently, the shaped article is set to a mold having the prepreg for forming the surface layer part laid on its inner surface and the mold is next clamped to mold the FRP hollow molded product by the inner pressure molding method. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to an internal pressure molding method for a hollow molded product of fiber reinforced plastic (FRP).

FRP is a thermosetting resin such as unsaturated polyester resin, epoxy resin, polyimide resin, matrix resin of thermoplastic resin such as polyethylene, polypropylene, polyamide, PPS, PEEK, carbon fiber, glass fiber, aramid fiber, etc. In recent years, it is used in a wide range of fields from the aerospace industry to the general industrial field because it is made of reinforcing fibers and is lightweight and excellent in strength properties.

Known methods for forming FRP into a tubular or hollow hollow member include centrifugal molding, pultrusion molding, filament winding molding, internal pressure molding, and the like. Among them, the internal pressure molding method is a method in which a cylindrical molding material is placed in a mold cavity, and this is heat-cured in a state where pressure is applied from the inside of the cylinder and is in close contact with the mold. Either thermosetting or thermoplastic is applicable, and is suitable for molding a normal hollow tubular FRP product (see, for example, Patent Documents 1 to 4).

In order to form a hollow FRP product by the internal pressure molding method, a prepreg is usually used, and an inflatable bag or tube (hereinafter referred to as an internal pressure bag) is placed inside the prepreg laminated on the inner surface of the mold cavity. . Next, a pressure bag molding method is generally used in which an internal pressure bag is inflated using compressed air or the like, pressure is applied from the inside of the mold, the prepreg is pressed against the inner wall surface of the mold, and the prepreg is heated and cured in this state to form. It is used for. As a heat curing means, conventionally, a method of heating from the outside using a curing furnace, an autoclave, a hot press or the like has been adopted. Patent Document 4 also proposes a method of using a heating medium for pressurizing the pressurizing bag.

JP-A 61-230925 JP-A-6-155595 JP 2003-334835 A JP 2006-130875 A

However, when the prepreg is laid and laminated on the inner surface of the mold cavity, or when layup products are set on the upper and lower molds of the mold and the mold is clamped, the inner pressure bag is the upper and lower molds. There is a problem that it becomes difficult to remove the internal pressure back after molding by biting into the overlap portion of the prepreg. It is possible to remove the internal pressure bag by molding it by wrapping the internal pressure bag with the lay-up product in advance. However, the shape of the shaped product will be destroyed, so that the end of the molded product will be damaged and surface wrinkles will occur. Problem has occurred.

An object of the present invention is to provide an internal pressure molding method for an FRP hollow molded article in which the above problems are improved.

In the invention described in claim 1 of the present invention, when an FRP hollow molded product is formed by an internal pressure molding method using a prepreg, first, the surface layer portion of the molded product is formed on the shaping die of the molded product. A prepreg other than the prepreg is laid and laminated to create a shaped article having an internal pressure bag inside, and then the shaped article is set in a mold laid with the prepreg for forming the surface layer portion on the inner surface. Then, the die is clamped and molded by an internal pressure molding method. This is an internal pressure molding method for an FRP hollow molded product.

The invention described in claim 2 is characterized in that one or two prepregs (synonymous with layer or ply) are laid on the inner surface of the mold as the prepreg for forming the surface layer portion. It is an internal pressure molding method of the described FRP hollow molded article.

According to the present invention, a hollow molded product made of FRP having excellent quality can be easily molded by an internal pressure molding method. One or two prepregs for surface layer formation are laid on the upper and lower molds of the mold, while the internal pressure bag can be wrapped with the remaining prepreg to prevent the internal pressure bag from being caught. An improved FRP hollow molded article is obtained.

In the present invention, when an FRP hollow molded product is formed by an internal pressure molding method using a prepreg, first, a prepreg other than the prepreg for forming the surface layer portion of the molded product is laid and laminated on the shaping die of the molded product. Then, a shaped article having an internal pressure bag inside is created. On the other hand,
A prepreg for forming the surface layer portion of the molded product is laid on the inner surface of the mold. At this time, one or two (layer or ply) prepregs are sufficient as the prepreg to be laid. Then, the prepared shaped product is set in a mold in which a prepreg for forming the surface layer portion is laid on the inner surface, and after the mold is clamped, an internal pressure bag is pressed and molded by an internal pressure molding method.

In this way, one or two prepregs for surface layer formation are laid on the upper and lower molds of the mold, while the internal pressure bag is wrapped with the remaining prepreg, and the shaped article (inner layup product having the internal pressure bag inside) ) And the combination of the two is set in the mold, so that the internal pressure bag can be prevented from biting during the internal pressure molding, and the appearance and appearance of the resulting molded product are also improved.

An example of the internal pressure molding method of the present invention will be described with reference to the drawings. In FIG. 1, 1 is an internal pressure bag, 2 is an upper mold of a mold, 3 is a lower mold of the mold, 2a and 3a are prepregs for forming a surface layer portion laid on the upper mold and the lower mold, respectively, and 4 is a surface layer section. A prepreg other than the prepreg for formation, and a combination of 1 and 4 is a shaped product. FIG. 1 shows an upper mold 2 and a lower mold 2 formed by molding a molded article and having a molded article having an internal pressure bag 1 and prepregs 2a and 3a for forming a surface layer on the inner surface. A state when the mold set between the molds 3 is clamped is shown.

When the mold is clamped as shown in FIG. 1, it is necessary that the bonding positions of the upper surface and the lower surface of the prepreg that are laid out are shifted for each layer. The method of shifting may be a staircase shape or a zigzag shape.

The internal pressure molding method in the present invention means a method in which a molding material such as a prepreg is placed in a mold cavity, and this is heat-cured in a state in which the material is brought into close contact with the mold by applying pressure from the inside of the cylinder. For example, a molding material such as a prepreg is wrapped around an internal pressure bag (pressurizing bag) formed of a flexible and heat-resistant material such as nylon or silicon rubber, or a shaping mold is used. This bag is placed in the center of the preformed molding material, placed in the mold cavity, pressurized medium is sent into the bag to inflate the bag, and the molding material is pressed against the inner surface of the mold and heat molded. Is the method. Usually, compressed air or the like is used as a pressurizing medium, and a heating furnace, autoclave, hot press or the like is used for heating. Alternatively, a heating medium may be introduced into the pressurizing bag, and pressurization and heating may be performed simultaneously. In the latter case, no special equipment or device for heating and curing is required.

In the present invention, an FRP hollow molded product is molded. The hollow molded product may have any cross-sectional shape as long as it is hollow. In addition, FRP is obtained by impregnating and curing a fiber reinforcing material with a matrix resin such as a thermosetting resin or a thermoplastic resin. However, in the present invention, regarding the fiber reinforcing material and the matrix resin to be used, There are no particular restrictions. Examples of the fiber reinforcing material include carbon fiber, glass fiber, aramid fiber, boron fiber, and metal fiber. Carbon fiber is preferred.

Examples of the thermosetting resin include epoxy resins, unsaturated polyester resins, phenol resins, vinyl ester resins, cyanate ester resins, urethane acrylate resins, phenoxy resins, alkyd resins, urethane resins, maleimide resins and cyanate ester resins. There are resins selected from prepolymerized resins. These can also be used as one type or a mixture of two or more types. Examples of thermoplastic resins include polypropylene, polysulfone, polyethersulfone, polyetherketone, polyetheretherketone, aromatic polyamide, aromatic polyester, aromatic polycarbonate, polyetherimide, polyarylene oxide, thermoplastic polyimide, and polyamideimide. is there. Two or more of these resins may be used in combination.

The fiber reinforcement is usually composed of warp and weft yarns such as plain weave, twill weave, satin weave, etc., fiber bundles are aligned in one direction, or stitched yarns in a perpendicular direction. It is used in the form of uniaxial woven fabrics sewn in the same manner, multi-axial woven fabrics obtained by laminating a plurality of sheet-like materials aligned in one direction at different angles and stitching them with a stitch thread in a perpendicular direction.

Examples of the pressurization or pressurization / heating medium of the internal pressure bag include air, heated air, water, hot water, water vapor, or heat transfer oil such as polyoxyalkylene glycol and silicone oil. Although the temperature of a heating medium changes with kinds of matrix resin used for FRP, it is the range of 50-200 degreeC normally.

The pressure of the internal pressure bag is sufficient as long as the molding material can be brought into close contact with the mold, and is usually about 4 to 9 kg / cm ² depending on the shape of the molded product. Specifically, the pressurizing medium may be introduced into the internal pressure bag so that the pressure of the internal pressure bag falls within this range.

As shown in FIG. 1, an elliptical hollow molded product having a flat cross section was formed. Using an aluminum mold, one prepreg (Toho Tenax Co., Ltd., W-3101 / Q-112, using plain woven fabric, containing 40% epoxy resin) on the inner surface of the upper mold and lower mold (1ply) ) Laminated. This forms the outermost layer of the molded article.

Using a molding mold similar in shape to the mold and having a smaller shape, the mold was laid and laminated on the upper mold of the molding mold from the second ply. The second ply was made smaller than the above 1ply, and the next ply was further reduced in size (stepped shape). For the lower mold of the shaping mold, the size of the prepreg is increased by the size of the upper mold, and when the upper mold and lower mold faces of the shaping mold are combined, the corresponding layers are in the plane position. I made it. Further, when the upper surface and the lower surface were matched, the internal pressure bag inserted between the upper surface and the lower surface was wrapped so as not to be caught in the wrap portion of the upper surface and the lower surface. Since the outermost layer of the molded product is directly laid on the mold, the required number of inner layer prepregs are laid and laminated on the shaping die.

When the upper surface and the lower surface that were laid and laminated on the shaping mold were combined, a nylon bag (WRIGHTLON # 7400, manufactured by AIRTECH) was inserted therein to obtain a shaped article having an internal pressure bag inside.

The shaped product obtained above was separately prepared as described above, set in a mold in which one prepreg was laid on the inner surface of the upper mold and lower mold (1ply), and after clamping, Molding was performed for 30 minutes to 1 hour by applying a pressure of 1 to 5 atmospheres at a temperature of 130 to 130 ° C. The hollow molded product obtained by demolding was of high quality with a beautiful appearance.

In the present invention, an FRP hollow molded product having a beautiful appearance can be easily molded by an internal pressure molding method, and thus there are significant industrial advantages.

It is a figure for demonstrating an example of the internal pressure molding method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal-pressure bag 2 Upper mold | type 2a, 3a Prepreg laid in mold (prepreg for surface layer part formation)
3 Lower mold of mold 4 Prepreg other than prepreg for surface layer formation

Claims (2)

When forming an FRP hollow molded product by an internal pressure molding method using a prepreg, first, a prepreg other than the prepreg for forming the surface layer portion of the molded product is laid and laminated on the shaping mold of the molded product, A shaped article having an internal pressure bag is created, and then the shaped article is set in a mold in which the prepreg for forming the surface layer portion is laid on the inner surface, and then the mold is clamped to form an internal pressure. An internal pressure molding method for FRP hollow molded products, characterized in that molding is performed by: 2. The internal pressure molding method for an FRP hollow molded article according to claim 1, wherein one or two prepregs are laid on the inner surface of the mold as the prepreg for forming the surface layer portion.

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