JP2002037904A - Fiber preform for molding, fiber-reinforced plastic and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fiber preform for molding, capable of molding an excellent FRP free from voids and an unimpregnated area. SOLUTION: This fiber preform for molding has the rate of the maximum impregnation rate of a liquid resin in the direction of a layer perpendicular to the thickness direction of a fiber sheet for molding to an impregnation rate of the liquid resin in the thickness direction of the fiber sheet for molding of 2 when one or plural laminated fiber sheets for molding composed of reinforced fiber are arranged in a mold, the liquid resin is injected to the mold and the one or plural laminated fiber sheets are molded. This fiber-reinforced plastic is produced by using the fiber preform for molding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber preform for molding used as a reinforcing material when molding fiber reinforced plastic (hereinafter, referred to as FRP), an FRP using the same, and a method for producing the same.

[0002]

2. Description of the Related Art As a forming fiber preform, for example, a bidirectional woven fabric in which a warp yarn and a weft yarn are orthogonal to each other, or a warp yarn is arranged in one direction, and the warp yarn is substantially bent. Use a woven fabric or the like woven with an auxiliary thread as a reinforcing material, and set multiple woven fabrics in the cavity formed by the upper mold and lower mold of the molding die, and then set them in the upper mold or lower mold Molding by resin transfer molding (RTM), which involves injecting a liquid resin into a mold through a resin injection port, is generally performed.
At that time, a fiber woven fabric having improved resin impregnation for the purpose of shortening the molding time or the like has been proposed in Japanese Patent Application Laid-Open Nos. 11-107105 and 11-107107.
However, simply improving the resin impregnating property may trap air in the mold due to the anisotropy of the resin impregnating rate of the fiber preform, leaving voids in the FRP or generating unimpregnated regions.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art. That is, an object of the present invention is to provide a fiber preform for molding capable of molding a good FRP without voids and unimpregnated regions by optimizing the directionality of the resin impregnation rate of the fiber preform for molding. Is to try.

[0004]

According to the present invention, in order to solve the above-mentioned problems, one or a plurality of molding fiber sheets made of reinforcing fibers are laminated and arranged in a mold, and a liquid resin is placed in the mold. A molding fiber preform in which the ratio of the maximum liquid resin impregnation rate in the layer direction orthogonal to the thickness direction to the liquid resin impregnation rate in the thickness direction of the molding fiber sheet when injecting and molding is 2 or less. I do. The present invention also provides
A fiber-reinforced plastic comprising the above-mentioned fiber preform for molding as a reinforcing material is provided. The present invention also provides a method for producing a fiber-reinforced plastic, comprising disposing the above fiber preform for molding in a mold as a reinforcing material, injecting and impregnating a liquid resin into the mold, and curing and integrating. .

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, in a fiber preform for molding, one or a plurality of fiber sheets for molding composed of reinforcing fibers are laminated and arranged in a mold, and a liquid resin is injected into the mold. When the ratio of the maximum liquid resin impregnation rate in the layer direction perpendicular to the thickness direction to the liquid resin impregnation rate in the thickness direction of the molding fiber sheet during molding is set to 2 or less, this molding fiber preform It is considered that voids do not remain in the FRP obtained by using the method and no unimpregnated region is generated for the following reasons.

First, FIG. 1 shows a bidirectional woven fabric in which a warp yarn 1 and a weft yarn 2 are orthogonal to each other, and shows a thickness direction and a layer direction of a forming fiber preform. The direction of 4 in the cross-sectional view along the cross-sectional line 3 is the thickness direction, and the plane direction orthogonal to it is the layer direction 5. Similarly, in the case of a molding fiber preform other than the bidirectional woven fabric, the surface including the fiber orientation direction is the layer direction, and the direction perpendicular to the layer direction is the thickness direction.

In FIG. 2, for example, a cavity 9 having a uniform thickness is formed by an upper mold 6 and a lower mold 7 of a molding die.
In the cavity 9, fiber preforms 10, 11, 1
2 and 3 plies are arranged, and the liquid resin is injected from the injection port 8 at the center of the lower mold 7. The air in the cavity is discharged from a portion where the upper mold and the lower mold are in contact with each other, and the resin is stopped in the cavity. For example, a soft pinch structure or the like can be applied. Further, the inside of the mold can be set in a reduced pressure state in advance.

[0008] The resin impregnation in the layer direction proceeds in the radial direction from the injection port. There are cases of impregnation with concentric circles and impregnation with anisotropy such as ellipse. Depends on the ratio of the resin impregnation rate in the thickness direction to the maximum resin impregnation rate in the layer direction. When the resin impregnation rate in the layer direction is higher than the resin impregnation rate in the thickness direction, particularly when the ratio of the maximum resin impregnation rate in the layer direction to the resin impregnation rate in the thickness direction exceeds 2, the constant as shown in FIG. The resin-impregnated region expands and expands as indicated by 13, 14, 15, and 16 over time. In this case, since the impregnation speed in the layer direction is high, the resin spreads along the surface of the lower mold 7 in the cavity, the resin flows around at the end of the cavity, and the air that has stopped in the cavity without being discharged is voids or unfilled air. The filling region 17 is formed. This is because even if the resin does not reach the end of the cavity,
Since the resin impregnation proceeds in the thickness direction after the resin impregnated layer is formed on the surface side of the mold, an air layer is formed near the surface of the upper mold 6 in the cavity, so that air is easily trapped, and similarly, voids and The filling region 17 is formed. These voids and unfilled areas become defects in the appearance and strength of the FRP molded product.

On the other hand, the ratio of the maximum resin impregnation rate in the layer direction to the resin impregnation rate in the thickness direction is 2 or less, preferably 1.
When it is 0 or less, the resin-impregnated region expands as indicated by 13, 14, 15, and 16 at regular intervals as shown in FIG. In this case, since the speed difference between the resin traveling along the surface of the lower mold 7 in the cavity and the resin traveling along the surface of the upper mold 6 in the cavity is small, the resin does not wrap around even when the resin reaches the end of the cavity. Therefore, no voids or unfilled regions are formed, and a product excellent in appearance and strength can be obtained as a FRP molded product.

A method for measuring the ratio of the resin impregnation rate in the layer direction and the thickness direction in the fiber preform for molding is as follows.
As shown in FIG. 2, a molding fiber preform is arranged in a cavity formed by the upper mold 6 and the lower mold 7 at a predetermined interval so as to have the same fiber content as that of the molded article. When the resin is injected and the resin reaches the upper mold 6 in the cavity, the contour of the resin impregnated region in contact with the surface of the lower mold 7 in the cavity and the contour of the lower mold 7 in the cavity with respect to the distance between the upper mold 6 and the lower mold 7. There is a method in which the ratio of the maximum distance between the surface and the injection port is measured to determine the ratio of the resin impregnation rate in the layer direction to the thickness direction of the fiber preform. The distance between the contour of the resin-impregnated region and the injection port means the distance from the center of the injection port to the contour of the resin-impregnated region from the end of the injection port in the radial direction. A highly transparent material such as tempered glass that does not substantially deform
When used for the lower mold 7, the progress of resin impregnation can be directly observed.

As a form of the fiber sheet for reducing the ratio of the resin impregnation rate in the layer direction to the thickness direction while keeping the basis weight of the fiber preform for molding constant, it is effective to have a through hole in the thickness direction. For example, in the case of a bidirectional woven fabric in which a warp yarn and a weft yarn made of carbon fibers cross each other, such an effect can be obtained by enlarging the void at the fiber intersection. The total area (hereinafter referred to as opening ratio) occupied by voids, such as between fiber yarns, relative to the surface area of the forming fiber sheet is 1 to 30%.
It is more preferable that the aperture ratio is 5 to 20%. Moreover, it is preferable to use a carbon fiber yarn having 1,000 to 50,000 filaments as the reinforcing fiber. One layer or a plurality of layers of the sheet-like material in which the reinforcing fiber yarns are arranged in one direction are laminated, and the layer of the sheet-like material of the reinforcing fiber yarns is assisted without substantially bending the reinforcing fiber yarns A fibrous material in a form woven by yarn can also be used as a forming fiber preform. In this case, when a plurality of layers of the sheet material are laminated and used, the direction of the reinforcing fiber yarn may be arranged so as to be different for each layer.

As a sizing agent for carbon fibers, (1) an ester compound of an alkylene oxide adduct of bisphenols (A) and an unsaturated dibasic acid having an acid value of 50 or more, (2) An ester of one or both of a diepoxy compound of bisphenols and an alkylene oxide-added diepoxy compound (B) of bisphenols and an unsaturated monobasic acid, and having an unsaturated group at one end of the main chain of the molecule. It is preferable to use an ester compound having an epoxy group at the other end, and (3) a composition containing a leveling agent as an essential component. Here, the alkylene oxide adduct (A) of bisphenols is more preferably a substance obtained by adding 2 to 4 mol of ethylene oxide or propylene oxide, and the leveling agent is a higher aliphatic ether type polyoxyethylene adduct. Higher fatty acid polyoxyethylene adduct, selected from the group consisting of higher fatty acid esters of polyhydric alcohols and polyoxyethylene adducts of higher fatty acid esters of polyhydric alcohols, and furthermore, a compound which is liquid at room temperature. preferable.

The molding fiber preform of the present invention can also be used as a three-dimensional preform in which fibers are bonded by a binder. As the binder, an epoxy resin, a vinyl ester resin, an unsaturated polyester resin, or the like dispersed in an aqueous liquid, a low-melting polymer such as nylon, polyester, or polyurethane, and a mixture thereof can be used.

[0014]

EXAMPLE In order to measure the ratio of the resin impregnation rate in the layer direction to the resin impregnation rate in the thickness direction of the fiber preform for molding, a cavity interval of 20 m having a shape as shown in FIG.
m using a flat type made of tempered glass, and laying a carbon fiber woven cloth “Pyrofil TR3110” (manufactured by Mitsubishi Rayon Co., Ltd.) (weight per unit area: 200 g / mm ² , opening ratio: 5%) in an area of 100 × 1
It was cut into 00 mm ² and 100 plies were placed in the cavity. This carbon fiber woven fabric is obtained by treating and weaving carbon fibers as follows. By reacting a 2 mol ethylene oxide adduct of bisphenol A with maleic anhydride, an ester compound (A1) having an acid value of 55 was obtained. Also, a bisphenol A type epoxy resin (EP828, manufactured by Yuka Shell) is reacted with methacrylic acid to obtain EP828.
/ EP828 one-terminal methacryl-modified epoxy resin (half ester) / EP828 both-terminal methacryl-modified epoxy resin (diester) at a mixing ratio of 1/2/1 (B
1) was obtained. The ester compound (A1) / the mixture (B1) / diisostearate polyoxyethylene (C
DIS-400, manufactured by Nippon Surfactant Industries) / Pluronic type nonionic surfactant F88 (manufactured by Asahi Denka) = 55/20/5/20, and emulsified in water by phase inversion emulsification. 2.8 including emulsifier
A weight% aqueous dispersion of a sizing agent was prepared. Next, a carbon fiber bundle TR30SX with 3,000 untreated sizing filaments (Pyrofil manufactured by Mitsubishi Rayon, strand strength 4300 MPa, strand elastic modulus 240 GP)
a) is immersed in a roller in the above-mentioned size aqueous dispersion, further dried with hot air, and then wound around a bobbin, whereby a sizing-processed carbon fiber having an attachment amount of 1.3% by mass of the sizing agent to the carbon fiber is obtained. A bundle of bobbins was obtained.
Next, using the above carbon fiber bundle, a plain weave cloth of 12.5 wefts / inch and 12.5 warps / inch is formed.
Weaving was performed at a speed of 20 mm / min.

From the center of the lower mold, a vinyl ester resin ("Neopol 8260" manufactured by Nippon Yupika Co., Ltd.) (0.5 Pa.
When s) was injected at a pressure of 0.1 MPa, the contour of the resin-impregnated region in contact with the lower mold surface in the cavity and the injection of the lower mold surface in the cavity were determined for the cavity spacing of 20 mm when the resin reached the upper mold. The maximum distance from the inlet was 15 mm, and the ratio was 0.75. Using 10 plies of this woven fabric so as to have the same fiber content, the above resin was injected at a pressure of 0.1 MPa from the center of the lower mold in an aluminum flat mold with a cavity interval of 2 mm and an area of 200 × 200 mm ^2. After the metered injection, it was stoppered and cured at 120 ° C. for 2 hours. When the FRP molded product was released from the flat mold and the appearance and strength were evaluated, there was no unfilled void or the like, and sufficient performance was exhibited as the strength.

As a comparative example, the resin impregnation rate ratio in the layer direction to the thickness direction of the molding fiber preform was measured under the same conditions as in the example except that a carbon fiber woven fabric having an opening ratio of 0.5% was used. It was 3. FRP molding is also performed in the same manner as in the example, and the FRP molded product is released from the flat mold,
When the appearance and strength were evaluated, many unfilled voids and the like were included, and sufficient performance could not be obtained as strength.

[0017]

As described above, by using the fiber preform for molding of the present invention, a good FR that does not cause unfilled regions such as voids in resin injection molding can be obtained.
A P-shaped product can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a thickness direction and a layer direction of a fiber preform for molding.

FIG. 2 is a schematic sectional view showing an example of a flat mold on which a fiber preform for molding is arranged.

FIG. 3 is a schematic cross-sectional view showing a resin impregnation behavior in a flat mold when a resin impregnation speed ratio in a layer direction to a thickness direction of a molding fiber preform exceeds 2.

FIG. 4 is a schematic cross-sectional view showing a resin impregnation behavior in a flat mold when a resin impregnation speed ratio in a layer direction to a thickness direction of a molding fiber preform is 2 or less.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Warp yarn 2 ... Weft yarn 3 ... Section line 4 ... Thickness direction 5 ... Layer direction 6 ... Upper die 7 ... Lower die 8 ... Injection port 9 ... Cavity 10 ... Fiber woven fabric 11 ... Fiber woven fabric 12 ... Fiber woven fabric 13 ... Resin Impregnation area 14 Resin impregnation area 15 Resin impregnation area 16 Resin impregnation area 17 Unfilled area

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 63/10 C08L 71/02 4L033 67/06 D06M 15/55 71/02 101: 40 D06M 15/55 B29C 67/14 L // D06M 101: 40 X (72) Inventor Yoshiharu Numata 4-1, Ushikawa-dori, Toyohashi-shi, Aichi Prefecture Sanyo Rayon Co., Ltd. Toyohashi Plant (72) Inventor Naoki Sugiura Ushikawa, Toyohashi-shi, Aichi Prefecture No. 1 at Toyohashi 4-chome, Toyohashi Plant (72) Inventor Tomoyuki Kotani 4-1-1, Ushikawadori, Toyohashi-shi, Aichi Prefecture No. 2 Toyohashi Plant, Miishi Rayon Co., Ltd. (72) Inventor Norihito Maki Aichi (1-2) Inventor Tsutomu Omiya 4, Ushikawa-dori, Toyohashi-shi, Aichi Prefecture F-term (reference) 4F072 AB10 AB28 AB30 AB33 AC05 AC06 AC12 AC13 AD23 AD38 AD43 AD44 AD53 AG02 AG17 AH03 AH12 AJ35 AK05 4F100 AA37A AA37B AD11A AD11B AK01B AK54A19 AK54B19A DG11B DH00A EH31A EH312 EJ082 EJ81A EJ822 GB16 GB71 JA20B JK14 YY00A YY00B 4F205 AA41 AD08 AD16 AD19 AG02 AG03 AR08 HA06 HA12 HA33 HA44 HB01 HB11 HC04 HG01 HM02 4J002 CD20X CF22 AD02 AD05 AD12

Claims (11)

[Claims] 1. A molding fiber sheet comprising reinforcing fibers.
One or a plurality of sheets are stacked and arranged in a mold, and a layer direction perpendicular to this thickness direction with respect to the liquid resin impregnation rate in the thickness direction of the forming fiber sheet when the liquid resin is injected into the mold and molded. The fiber preform for molding, wherein the ratio of the maximum liquid resin impregnation rate is 2 or less. 2. The fiber sheet for molding has 10 filaments.
2. The method according to claim 1, which is composed of 00 to 50,000 carbon fiber yarns.
The fiber preform for molding according to the above. 3. The forming fiber sheet is a bidirectional woven fabric in which warp yarns and weft yarns cross each other.
Or the fiber preform for molding according to 2. 4. A sheet-like reinforcing fiber yarn comprising one layer or a plurality of layers of a sheet-like material in which reinforcing fiber yarns are arranged in one direction, without substantially bending the reinforcing fiber yarns. The fiber preform for molding according to claim 1 or 2, wherein the layer of the product is woven by an auxiliary yarn. 5. The molding fiber preform according to claim 1, wherein a plurality of laminated molding fiber sheets are bonded with each other by a binder. 6. The molding fiber according to claim 1, wherein the total area of the voids penetrating in the thickness direction with respect to the surface area of the molding fiber sheet is 1 to 30% of the surface area. preform. 7. The reinforcing fiber is (1) an ester compound of an alkylene oxide adduct of bisphenols (A) and an unsaturated dibasic acid, the ester compound having an acid value of 50 or more; (2) bisphenols And an ester of an unsaturated monobasic acid with one or both of a diepoxy compound of the formula (I) and an alkylene oxide-added diepoxy compound (B) of a bisphenol having an unsaturated group at one end of the main chain of the molecule. The fiber preform for molding according to any one of claims 1 to 6, comprising a carbon fiber having a sizing agent containing, as an essential component, an ester compound having an epoxy group at the other end, and (3) a smoothing agent. . 8. The molding fiber preform according to claim 7, wherein the alkylene oxide adduct (A) of bisphenol is obtained by adding 2 to 4 mol of ethylene oxide or propylene oxide. 9. A polyoxyethylene addition of a higher aliphatic ether polyoxyethylene adduct, a higher fatty acid polyoxyethylene adduct, a higher fatty acid ester of a polyhydric alcohol and a higher fatty acid ester of a polyhydric alcohol as a leveling agent. The molding fiber preform according to claim 7 or 8, wherein the molding fiber preform is a compound selected from the group consisting of a product and a liquid at room temperature. 10. A fiber-reinforced plastic comprising the fiber preform for molding according to claim 1 as a reinforcing material. 11. A method comprising arranging a fiber preform for molding according to any one of claims 1 to 9 as a reinforcing material in a mold, injecting and impregnating a liquid resin into the mold, and curing and integrating. Manufacturing method of fiber reinforced plastic.