JP2004058610A - Semi-impregnated prepreg and molding method using this prepreg - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a prepreg from which a molded product free from residual air and reduced in voids is manufactured, and a manufacturing method using this prepreg. <P>SOLUTION: This semi-impregnated prepreg 1 is composed of a thermosetting resin film 5 and fiber-reinforcing materials 2 and 3 laminated on at least one side of the film 5 and has a projecting fibrous part 9 formed on at least a part of the peripheral end part S of the semi-impregnated prepreg 1. The thermosetting resin film 5 may use a carrier. The prepreg is best-suited for use in vacuum bag molding and autoclave molding processes. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a semi-impregnated prepreg having a protruding fiber portion at a peripheral end thereof, and laminating and attaching a fiber reinforcing material to a thermosetting resin film, and a molding method using the prepreg.
[0002]
[Prior art]
A prepreg is a molding material obtained by impregnating a fiber reinforced material with a thermosetting resin and proceeding a curing reaction to such an extent that it can be easily handled manually. A prepreg mainly composed of a fiber reinforcing material such as carbon fiber, boron fiber, and aramid fiber and an epoxy-based resin is used.
[0003]
The prepreg is formed by heating and curing a plurality of prepregs laid in a mold under pressure. As a method for forming a prepreg, an autoclave forming method, a vacuum bag forming method, an internal pressure bag forming method, or the like is used as a method using a flexible bag having elasticity.
[0004]
In the autoclave molding method and the vacuum bag molding method, first, a bag is placed on a prepreg laid on a mold to seal the prepreg, and the inside of the bag is evacuated using a vacuum pump or the like. If the inside of the bag is evacuated under the atmospheric pressure, the bag comes into close contact with the mold and the discharge of air is hindered. In this case, an air pocket is formed between the bag and the mold, and the air pocket is left behind, so that an operation of forcibly removing the remaining air is required.
[0005]
Further, the prepreg has a tack on its surface due to its structure, and air is trapped between the prepregs when laminating. Vacuum bag molding, in which pressure molding is performed at atmospheric pressure without sufficient external pressure, does not require equipment such as an autoclave, so molded products can be easily obtained at low manufacturing cost. The resulting molded article has a problem that voids are generated due to remaining air, and the physical properties of the molded article are reduced.
[0006]
As a device for preventing the generation of such voids, WO 00/27632 discloses a molding material in which a fiber reinforcing material is stacked on at least one surface of a resin layer. Also, Japanese Patent Application Laid-Open No. 5-269909 discloses a method using a resin film of a fiber reinforced material and a thermosetting resin instead of a prepreg. In this method, a fiber reinforced material and a resin film are stacked and then heated to impregnate the resin of the resin film into the fiber reinforced material and harden to obtain a molded product.
[0007]
The method using these molding materials can suppress generation of voids to some extent without performing autoclave molding in which pressure is applied from the outside. However, it is inevitable that voids and pinholes are generated, although the number is smaller than that of the conventional prepreg.
[0008]
[Problems to be solved by the invention]
An object of the present invention is to provide a high degree of exhaustability in the bag under atmospheric pressure, especially when forming by vacuum bag forming, air does not remain in the fiber reinforced material, and voids are formed in the fiber reinforced material. An object of the present invention is to provide a semi-impregnated prepreg and a molding method capable of obtaining a small molded product.
[0009]
[Means for Solving the Problems]
The present invention that solves the above-mentioned problems is described below.
[0010]
[1] A semi-impregnated prepreg comprising a thermosetting resin film and a fiber reinforcing material stuck on at least one surface thereof, wherein the semi-impregnated prepreg has a protruding fiber portion on at least a part of a peripheral end portion of the semi-impregnated prepreg. Prepreg.
[0011]
[2] The semi-impregnated prepreg according to [1], wherein the protruding fiber portion is one in which fibers constituting the fiber reinforced material extend from the fiber reinforced material.
[0012]
[3] The semi-impregnated prepreg according to [1] or [2], wherein the thermosetting resin film has a resin layer formed on at least one surface of a carrier.
[0013]
[4] The semi-impregnated prepreg according to [3], wherein the protruding fiber portion is one in which fibers constituting the carrier extend from the carrier.
[0014]
[5] A semi-impregnated prepreg comprising a thermosetting resin film, a fiber reinforcing material stuck on at least one surface thereof, and sheet-like fibers larger than the film or the fiber reinforcing material, wherein the semi-impregnated prepreg is A semi-impregnated prepreg formed by forming a protruding fiber portion of a sheet-like fiber on at least a part of a peripheral end of the prepreg.
[0015]
[6] A molding method for performing vacuum bag molding using the semi-impregnated prepreg according to any one of [1] to [5].
[0016]
[7] A molding method for performing autoclave molding using the semi-impregnated prepreg according to any one of [1] to [5].
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows a schematic cross-sectional view of an example of the semi-impregnated prepreg of the present invention. The semi-impregnated prepreg 1 is formed by attaching fiber reinforcements 2 and 3 to a thermosetting resin film 5. The semi-impregnated prepreg 1 has a protruding fiber portion 9 in which the fibers constituting the fiber reinforcements 2 and 3 extend without being cut at the peripheral end S.
[0018]
The fiber reinforcements 2 and 3 include a resin-impregnated layer 7 impregnated with the resin of the thermosetting resin film 5 and an unimpregnated layer 8 not impregnated with the resin. The semi-impregnated prepreg 1 is not impregnated with the resin up to the surface, and no tack is generated on the surface of the prepreg.
[0019]
As the fiber reinforcement, carbon fiber, glass fiber, aramid fiber, boron fiber, metal fiber, and other reinforcing fibers used in ordinary prepregs can be used. Among them, carbon fiber, glass fiber and aramid fiber are preferred. The form of these fiber reinforced materials is not particularly limited as long as the protruding fiber portion can be drawn out, and for example, ones aligned in one direction, ones aligned in multiple directions, and a woven fabric can be used. Among them, when a woven fabric is used, the warp yarn and the weft yarn of the woven fabric can be easily extended and used as a protruding fiber portion, which is preferable.
[0020]
The length of the protruding fiber portion extending from the fiber reinforcing material is preferably from 10 to 100 mm, more preferably from 10 to 50 mm.
[0021]
In semi-impregnated prepreg of the present invention, the basis weight of the fibrous reinforcement is preferably ^{200~3000g / m 2, 400~2000g / m} 2 is more preferable.
[0022]
As shown in FIG. 1, when a fiber-reinforced material is stuck on both sides of a thermosetting resin film to form a semi-impregnated prepreg, the fiber-reinforced materials 2 and 3 are each a plane-symmetric woven fabric, or are thermoset. It is preferable that the fabrics are plane-symmetric with respect to the conductive resin film 5. By using plane-symmetric or plane-symmetric textiles, it is possible to prevent the prepreg from warping when the fiber reinforced material is stacked.
[0023]
As a plane-symmetric fabric or a fabric which can be made plane-symmetric with respect to each other, a multiaxial fabric can be mentioned. The multiaxial woven fabric refers to a woven fabric obtained by laminating sheet-like fiber reinforced materials aligned in one direction at different angles and knitting them with nylon yarn, polyester yarn, glass fiber yarn, or the like.
[0024]
Examples of plane-symmetric multiaxial fabrics include [+ 45 / -45 / -45 / + 45] and [0 / + 45 / -45 / -45 / + 45/0]. Examples of combinations of multiaxial fabrics that are symmetrical to each other include [+ 45 / −45] and [−45 / + 45], [0 / + 45 / −45], [−45 / + 45/0], and [+ 45 / 0 / -45 / 90] and [90 / -45 / 0 / + 45]. The angle at which the fiber reinforced materials aligned in one direction are stacked is not limited to these, and may be any angle.
[0025]
The thickness of the multiaxial woven fabric is appropriately selected depending on the application, but is preferably 0.2 to 3 mm.
[0026]
As the resin used for the thermosetting resin film, a thermosetting resin used for normal prepreg production can be used. Specifically, epoxy resin, unsaturated polyester resin, phenol resin, melamine resin, polyurethane resin, silicone resin, maleimide resin, vinyl ester resin, cyanate ester resin, resin obtained by pre-polymerizing maleimide resin and cyanate ester resin, etc. In the present invention, a mixture of these resins can also be used. When a fiber-reinforced composite material is used, an epoxy resin composition having excellent heat resistance, elastic modulus, and chemical resistance is preferable. These thermosetting resins may contain a curing agent, a curing accelerator, and the like.
[0027]
The curing temperature of the thermosetting resin is preferably adjusted to 60 to 180 ° C, more preferably 70 to 130 ° C.
[0028]
The resin content of the resin film is preferably 35 to 55% based on the total weight of the semi-impregnated prepreg.
[0029]
The thermosetting resin used for the resin film is preferably a prepolymer that has been polymerized to an extent having a certain shape retention ability at room temperature, and has a viscosity of 0.1 to 10 Pa · s when heated.
[0030]
Further, in order to enhance the handleability of the thermosetting resin film, it is preferable to use a carrier for the thermosetting resin film. A thermosetting resin film in which a resin layer is formed on one or both surfaces of a carrier is provided with shape retention and is excellent in handleability. As the carrier, a glass fiber sheet, a carbon fiber sheet, an aramid fiber sheet, a polyester sheet, a polyethylene sheet, and a cellulose fiber sheet can be used.
[0031]
FIG. 2 shows another example of the semi-impregnated prepreg of the present invention. In this example, the resin film includes a carrier 16 and resin layers 14 and 15 formed on the carrier 16. The resin film has a sheet-like carrier 16 interposed substantially in the center, and the fibers constituting the carrier 16 extend from the peripheral end S of the protruding fiber portion 19.
[0032]
In the semi-impregnated prepreg shown in FIG. 2, the same fiber reinforced material, thermosetting resin film, and carrier as described above are used. The protruding fiber portion may have any of a single fiber shape, a woven shape, and a non-woven shape.
[0033]
Although FIGS. 1 and 2 show the case where the fiber reinforcing material is stacked on both sides of the resin film and attached, it may be stacked only on one side.
[0034]
The semi-impregnated prepreg of the present invention may have a protruding fiber portion at the peripheral end portion, and the protruding fiber portion is not limited to a fiber reinforcing material or a carrier-derived material, and a separately protruding fiber portion is prepared and sandwiched. It may be formed as follows.
[0035]
Further, a thermosetting resin film, a fiber-reinforced material attached to at least one surface thereof, and a semi-impregnated prepreg composed of a sheet-like fiber larger than the film or the fiber-reinforced material, and at least a part of a peripheral end portion. Alternatively, a protruding fiber portion of the sheet-like fiber may be formed.
[0036]
The protruding fiber portion may be present at a part of the periphery of the semi-impregnated prepreg, but it is more effective and preferable to exist over the entire periphery.
[0037]
The semi-impregnated prepreg of the present invention exerts an effect like an air bleeder when a vacuum bag molding method and an autoclave molding method described below are used to exhaust the air between the bag and the mold and reduce the pressure. Thus, air in the fiber reinforced material can be effectively removed.
[0038]
The method for producing a semi-impregnated prepreg of the present invention comprises laminating a fiber reinforcing material on one side or both sides of a thermosetting resin film, and applying a pressure of 0.01 to 0.5 MPa and a pressure of 25 to 100 ° C. It can be manufactured by heating for minutes. As shown in FIG. 2, a prepreg in which a carrier is interposed substantially at the center of a thermosetting resin film is manufactured by forming a resin layer on both surfaces of the carrier and further attaching a fiber reinforcing material to the resin layer.
[0039]
The impregnation of the resin of the thermosetting resin film into the fiber reinforced material only needs to be such that the resin does not impregnate the prepreg surface, but is preferably 0 to 70% of the thickness of the fiber reinforced material, and is 5 to 50%. Is more preferable.
[0040]
Hereinafter, a molding method using the semi-impregnated prepreg of the present invention will be described with reference to FIG.
[0041]
First, a semi-impregnated prepreg 1a composed of fiber reinforcing materials 2a and 3a and a thermosetting resin film 5a is laid on one surface of a mold 24. After laying the semi-impregnated prepreg 1a, the bags 20 are placed one on top of the other, and the periphery of the bag 20 is hermetically sealed with the mold 24 with a sealant 22 (FIG. 3A).
[0042]
The material of the bag is not particularly limited, and a commonly used known material can be used. Furthermore, the shape of the bag is not particularly limited, and a shape such as a sheet shape or a bag shape can be appropriately selected and used depending on the shape of a mold and a target molded product. Further, the bag may be sealed as long as the semi-impregnated prepreg can be tightly adhered to the mold under reduced pressure. For example, as shown in FIG. 3, a method of directly sealing a bag to a mold with a sealant, a method of laying a semi-impregnated prepreg in a bag-like bag and sealing the periphery of the bag to the mold, and a method of stacking on a semi-impregnated prepreg For example, a method of hermetically sealing one arranged bag and another bag arranged on the other surface of the mold with a sealant can be exemplified. The method of sealing the bags and covering the entire mold with the bag is particularly effective when there is a jig mounting hole and it is not possible to seal even if the mold is directly sealed, or when the mold is formed of a breathable material. is there.
[0043]
After the semi-impregnated prepreg is sealed using the bag, the gas between the mold 24 and the bag 20 is exhausted to reduce the pressure (FIG. 3B). By reducing the pressure between the mold 24 and the bag 22, the bag is deformed and the semi-impregnated prepreg 1a comes into close contact with the mold 24. With the deformation of the bag, the protruding fiber portion 9a is interposed between the bag 20 and the mold 24 to secure an air flow path and prevent air accumulation and voids.
[0044]
Further, the thermosetting resin film is melted by heating using an oven (vacuum bag molding) or an autoclave (autoclave molding), and the fiber reinforcing material is impregnated with the thermosetting resin. Further, the thermosetting resin impregnated in the fiber reinforcement is cured by heating to obtain molded articles 30 as cured layers 26 and 28 (FIG. 3C). The heating temperature in an oven or the like is preferably from 60 to 180 ° C. The pressurizing pressure when using an autoclave is preferably 0.1 to 0.5 MPa. Further, it is preferable to perform these processes while exhausting the gas between the mold 24 and the bag 22.
[0045]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples.
[0046]
Example 1
80 parts by mass of Epicoat 828 (manufactured by Japan Epoxy Resin), 20 parts by mass of Epicoat 1001 (manufactured by Japan Epoxy Resin), 5 parts by mass of dicyandiamide (manufactured by Japan Epoxy Resin), 3- (3,4-dichlorophenyl) 5 parts by mass of -1,1-dimethylurea (manufactured by Houshiya Chemical Industry Co., Ltd.) was weighed and kneaded at 70 ° C. with a roll mill to obtain a resin composition. Thereafter, a resin film having a resin weight of 1000 g / m ² and a width of 1000 mm was prepared at 70 ° C. by a doctor blade method, and a net-shaped woven fabric made of glass fiber having a width of 1100 mm, Clenet G1100 (manufactured by Kurabo Industries) was formed on one surface of the resin film. By sticking, a resin film with a carrier was obtained. In addition, both ends of the carrier protruded from the resin-coated portion by 50 mm in width.
[0047]
A 1000 mm wide multiaxial woven fabric ([0 / + 45 / -45]: CF basis weight 600 g / m ² ) using carbon fiber HTA-12K (manufactured by Toho Tenax Co., Ltd.) on both surfaces of a resin film with a carrier and a 1000 mm wide A shaft fabric ([−45 / + 45/0]: CF basis weight: 600 g / m ² ) is bonded at a pressure of 0.1 MPa at a speed of 2 m / min with a heating roller heated to 70 ° C., and a fiber having a width of 50 mm at both ends. A semi-impregnated prepreg of [0 / + 45 / -45] / resin film / [-45 / + 45/0] having a protrusion was obtained.
[0048]
The semi-impregnated prepreg [0 / + 45 / -45] / resin film / [-45 / + 45/0] having a width of 1100 mm and a length of 500 mm is laminated on a flat aluminum plate subjected to a mold release treatment. Was laminated with a peel cloth. Thereafter, the entire laminated material was covered with a nylon bag (WRIGTLON # 7400, manufactured by AIRTECH), the mold and the nylon bag were sealed with a sealant tape, and the inside of the bag was evacuated with a vacuum pump.
[0049]
Thereafter, the semi-impregnated prepreg was heated and cured in a curing furnace at 130 ° C. for 2 hours while reducing the pressure with a vacuum pump to obtain a 1.5 mm-thick CFRP plate. As a result of inspecting the inside of the CFRP plate with an ultrasonic flaw detector, there was no void inside, and a good plate was obtained.
[0050]
Example 2
80 parts by mass of Epicoat 828 (manufactured by Japan Epoxy Resin), 20 parts by mass of Epicoat 1001 (manufactured by Japan Epoxy Resin), 5 parts by mass of dicyandiamide (manufactured by Japan Epoxy Resin), 3- (3,4-dichlorophenyl) 5 parts by mass of -1,1-dimethylurea (manufactured by Houshiya Chemical Industry Co., Ltd.) was weighed and kneaded at 70 ° C. with a roll mill to obtain a resin composition. Thereafter, a resin film having a resin weight of 1000 g / m ² was prepared at 70 ° C. by a doctor blade method. ^Two resin films each having a resin weight of 1000 g / m ² were stacked to obtain a resin film having a resin weight of 2000 g / m ² and a width of 1000 mm.
[0051]
A 1000 mm wide multiaxial woven fabric ([0 / + 45 / -45]: CF basis weight 600 g / m ² ) and a 1000 mm wide multiaxial woven fabric ([−45 / + 45) using carbon fiber HTA-12K (manufactured by Toho Tenax Co., Ltd.) / 0]: Clenet G1100 (manufactured by Kurabo Co., Ltd.), a net-like woven fabric made of glass fibers having a width of 1100 mm, is sandwiched between CF fabric weights of 600 g / m ² ), and is stitched with a polyester yarn in the thickness direction. A woven fabric with a protruding fiber portion was obtained.
[0052]
On both surfaces of the resin film, the above-mentioned woven fabric with a protruding fiber portion is adhered at a pressure of 0.1 MPa at a speed of 2 m / min with a heating roller heated to 70 ° C. An impregnated prepreg was obtained.
[0053]
Thereafter, the semi-impregnated prepreg cut into a width of 1100 mm and a length of 500 mm was laminated on a flat aluminum plate subjected to a release treatment, and a peel cloth was laminated thereon. The whole laminated material was covered with a nylon bag (WRIGTLON # 7400, manufactured by AIRTECH), the mold and the nylon bag were sealed with a sealant tape, and the inside of the bag was evacuated with a vacuum pump.
[0054]
Thereafter, the semi-impregnated prepreg was heated and cured in a curing furnace at 130 ° C. for 2 hours while reducing the pressure with a vacuum pump to obtain a CFRP plate having a plate thickness of 2.8 mm. As a result of inspecting the inside of the CFRP plate with an ultrasonic flaw detector, there was no void inside, and a good plate was obtained.
[0055]
Comparative Example 1
80 parts by mass of Epicoat 828 (manufactured by Japan Epoxy Resin), 20 parts by mass of Epicoat 1001 (manufactured by Japan Epoxy Resin), 5 parts by mass of dicyandiamide (manufactured by Japan Epoxy Resin), 3- (3,4-dichlorophenyl) 5 parts by mass of -1,1-dimethylurea (manufactured by Houshiya Chemical Industry Co., Ltd.) was weighed and kneaded at 70 ° C. with a roll mill to obtain a resin composition. Thereafter, a resin film having a resin weight of 1000 g / m ² was prepared at 70 ° C. by a doctor blade method to obtain a resin film.
[0056]
A multiaxial woven fabric ([0 / + 45 / -45]: CF basis weight 600 g / m ² ) using carbon fiber HTA-12K (manufactured by Toho Tenax Co., Ltd.) on both surfaces of the resin film and ([−45 / + 45/0]) : CF weight: 600 g / m ² ) with a heating roller heated to 70 ° C. at a pressure of 0.1 MPa at a speed of 2 m / min, [0 / + 45 / −45] / resin film / [− 45 / + 45] / 0] was obtained.
[0057]
The semi-impregnated prepreg [0 / + 45 / -45] / resin film / [-45 / + 45/0] having a width of 1000 mm and a length of 500 mm was laminated on a flat aluminum plate subjected to a mold release treatment. Was laminated with a peel cloth. Thereafter, the entire laminated material was covered with a nylon bag (WRIGTLON # 7400, manufactured by AIRTECH), the mold and the nylon bag were sealed with a sealant tape, and the inside of the bag was evacuated with a vacuum pump.
[0058]
Thereafter, the semi-impregnated prepreg was heated and cured in a curing furnace at 130 ° C. for 2 hours while reducing the pressure with a vacuum pump to obtain a CFRP plate having a thickness of 1.5 mm. As a result of inspecting the inside of the CFRP plate with an ultrasonic flaw detector, five 4 mm ² voids were generated inside.
[0059]
【The invention's effect】
The semi-impregnated prepreg of the present invention has a protruding fiber portion at the peripheral end, and when the prepreg is sealed and depressurized using a bag, the protruding fiber portion secures a flow path of air, so that air inside the prepreg is reduced. A molded product that is easy to come off and has few voids can be obtained, and is suitable for vacuum bag molding and autoclave molding.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing an example of a semi-impregnated prepreg of the present invention.
FIG. 2 is a schematic sectional view showing another example of the semi-impregnated prepreg of the present invention.
FIG. 3 is a flowchart showing an example of a molding method using the semi-impregnated prepreg of the present invention, where (a) is a cross-sectional view showing a state in which the prepreg is sealed between a bag and a mold, and (b) is a sectional view showing the bag. FIG. 3 is a cross-sectional view showing a state where the space between the mold and the mold is exhausted, and FIG.
[Explanation of symbols]
1, 1a, 10 Semi-impregnated prepreg 2, 3, 12, 13 Fiber reinforcement 5 Thermosetting resin film 7, 17 Resin impregnated layer 8, 18 Non-impregnated layer 9, 9a, 19 Protruding fiber portion 14, 15 Resin layer 16 Carrier 20 Bag 22 Sealant 24 Mold 26, 28 Hardened layer 30 Molded product S Peripheral end

Claims (7)

A semi-impregnated prepreg comprising a thermosetting resin film and a fiber reinforcing material adhered to at least one surface thereof, wherein the semi-impregnated prepreg has a protruding fiber portion at least at a part of a peripheral end of the semi-impregnated prepreg. 2. The semi-impregnated prepreg according to claim 1, wherein the protruding fiber portion is one in which the fibers constituting the fiber reinforcing material extend from the fiber reinforcing material. 3. The semi-impregnated prepreg according to claim 1 or 2, wherein the thermosetting resin film has a resin layer formed on at least one surface of a carrier. 4. The semi-impregnated prepreg according to claim 3, wherein the protruding fiber portion is a fiber in which a fiber constituting the carrier extends from the carrier. A thermosetting resin film, a semi-impregnated prepreg comprising a fiber reinforced material stuck on at least one surface thereof, and sheet-like fibers larger than the film or the fiber reinforced material, wherein the semi-impregnated prepreg has a peripheral end. A semi-impregnated prepreg formed by forming a protruding fiber portion of a sheet-like fiber on at least a part of the portion. A molding method for performing vacuum bag molding using the semi-impregnated prepreg according to any one of claims 1 to 5. A molding method for performing autoclave molding using the semi-impregnated prepreg according to any one of claims 1 to 5.

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