JPH0580329B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention Products formed from braided fibers usually offer great freedom in design and have the advantages of high impact strength and resistance to delamination. Also, this type of fiber can be easily mixed into various hybrid fabrics. Therefore, braided fibers are widely used in the production of composite materials. BACKGROUND OF THE INVENTION There are two conventional methods for producing braided fibers. One method consists of braiding a roving of fibers into a sleeve, cutting them to the appropriate length, and then placing them layer by layer on the core of a die, which is then placed in the cavity of the die. A resin material is injected into this cavity and allowed to harden into the desired shape. Prior art regarding this type of method is for example WIPO Patent No. 8603268, Japanese Patent No.
59196218 and 58170963 and European Patent No.
Described in No. 77665. This type of method results in (a) poor compatibility between the braided product and the die; (b) difficulty in handling the separate layers covering the core, which can deform or break the fibers and reduce strength. (c) the complicated operating steps contaminate the working environment and the worker's skin is therefore susceptible to damage and itching from contact with the fibers; (d) the production rate or yield is low; etc. It has the following disadvantages. The other method for manufacturing braided fibers is the pre-preg globbing method, which involves first impregnating fiber rovings with resin to form pre-preg glovings, and then knitting the pre-preg groves using a braiding machine to produce braided fiber prepregs. Consisting of This method is disclosed in Japanese Patent No. 59155897 and US Patent Nos. 4371180 and 4517039. This kind of method
(a) low production rates and therefore high manufacturing costs; (b)
It has shortcomings such as: (c) it is extremely difficult to arrange the layers one by one on the core or on the expandable tube (for example, cellophane tube); The present invention provides a new method for continuously producing single-layer or multi-layer braided fiber prepregs. Summary of the Invention The method for continuously manufacturing single-layer or multi-layer braided fiber prepreg of the present invention involves braiding roving, impregnating the resulting braided body (blade) with a resin transferred into the cavity of a mold, and then impregnating the prepreg with a resin transferred into the cavity of a mold. It consists of winding into the shape of a single-layer or multi-layer braided fiber prepreg by means of a winding device. The method of the invention can be operated integrally and continuously;
An otherwise complex manufacturing step is thus simplified. Furthermore, the single-layer or multi-layer braided fiber prepregs obtained by this method can be used in a wide range of different products for different purposes. Furthermore, the method of the present invention has the following advantages. (a) mass production possible and low cost; (b) because the fibers are processed in only a single step, the possibility of fiber breakage or deformation is small and torsional strength is high; (c) the fibers are inter-hybridization between layers.
(d) It is easy to handle, resulting in less environmental pollution and less damage to the skin of workers. (e) the operational steps are simplified as the braid can be easily placed on the core or compressed directly by internal inflatable tubes; (f) the pot life and storage methods are the same. , easier to manage than normal unidirectional fiber prepreg. Specific Example In the continuous manufacturing method of the present invention, first, a multilayer braiding machine is used to attach fiber roving to an expandable tube (this tube is elastic,
(can be formed of any polymeric material commonly used in the manufacture of tubes exhibiting gas impermeability and heat resistance) or braided onto a sleeve-like release film to form a single-layer or multi-braided sleeve of triaxial construction. Possibly a single-layer or multi-layer braided fiber prepreg is produced. The braided sleeve is then pulled through a plurality of drive rollers and introduced into a mold used for resin transfer and braid impregnation. Before injecting the resin into the mold, the resin is thoroughly mixed with an appropriate amount of curing agent in a resin transfer molding machine, and then a specific amount is introduced into the mold cavity under predetermined temperature and pressure conditions. The braid entering the mold is impregnated. The amount of resin mixture is controlled by adjusting the spacing between die openings. As the impregnated product exits the die opening, it is sandwiched between two layers of release paper or release film, and in this state passes through a hot pressing device (consisting of an ironing plate and a pressing roller). The prepreg is degassed by pressing rollers and thoroughly impregnated. When this is cooled in a chiller, a B-stage prepreg is obtained. Finally, this prepreg is wound up in a winding device and ready for use in the production of single-layer or multi-layer braided prepreg. As shown in FIG. 1, an expandable tube or sleeve-like release film 1 passes through the center of a multilayer braider 4. As shown in FIG. The carrier 2 begins to move and braids the fibers 3 onto the inflatable tube. This braided sleeve then enters the mold 7. Resin tank 5 and curing agent tank 6
The component resin and curing agent are respectively supplied from the mold 7, and these substances are mixed and then poured into the mold 7. As a result, the braided fibers are impregnated with resin within the mold 7.
The prepreg emerges from the mold 7 and is fed to an ironing plate 10. Before transferring to the plate 10, the prepreg is first placed between two release paper or release film layers 8. This paper or film is fed by guide rollers 9 and sandwiches the braided fibers in a sandwich pattern. The ironing plate 10 provides heat to control the viscosity of the resin, and the pressing rollers 11 degas the prepreg passing through it to complete the impregnation. The prepreg is then passed over a chiller 12, resulting in a B-stage prepreg material. This material is stretched by a drive roller 13 and wound into a roll by a winding device 15. A trimmer 14 is also used when a product of a certain length is desired. 2 and 3 show the mold 7 in a front view and a side view, respectively. The resin is introduced through the inlet 16 and flows to fill the cavity of the mold 7. The braided fibers are introduced through openings 17 and delivered through openings 18. Inside the mold 7 there is a taper between the openings 17 and 18. The resin content can be controlled by adjusting the size of this taper. The size of this opening may vary depending on the number of fiber layers. FIG. 4 shows a heating device for the mold 7. Heating plates 23 are fixed to the top and bottom of the mold 7 and are connected to a power source 22 so that the mold temperature can be controlled. The viscosity of the resin can be adjusted by controlling the mold temperature to obtain fibers that are fully impregnated with resin. FIG. 5 shows the product of the invention in cross section. The core is an expansible tube or sleeve-like release film 1 with longitudinal fibers 19 evenly distributed on said sleeve and fibers 20 woven at specific angles.
are also regularly dispersed in the resin 21, thus forming a triaxial structured braided body. Multilayer braiding machines can be used to produce multilayer braided fiber prepregs that meet the quality requirements of the final product. The fibers used in the present invention are typically glass fibers, carbon fibers, Kevlar fibers (Aramid) and any other materials that can be used in composites. All fibers start out as long continuous fibers, such as rovings,
Must be thread, filament, etc. The fiber braiding angle is between 15° and 80° (with the axial direction being 0°), preferably between 30° and 45°. The fiber content is between 31 and 61% by volume, preferably between 40 and 50% by volume, based on the volume of the prepreg. The expansible tube or sleeve release film used in the process of the present invention is comprised of cellophane, polypropylene, polyester and nylon or other polymeric materials. The resin used in the production method of the present invention contains a curing agent and/or a filler. Suitable resins include thermosetting resins commonly used in composite materials, such as phenolic aldehyde resins, unsaturated polyester resins,
Epoxy resins, silicone resins and polyimide resins or other polymers may be mentioned. The user can select any suitable resin. The choice of curing agent also depends on the resin used. Fillers may be used optionally depending on the requirements needed for the final prepreg. In the present invention, the braiding operation is performed on a multilayer triaxial braiding machine. The braiding speed is preferably 1-3 m/min, the diameter of the braid body is 13-90 cm, and the braid angle is (axis direction
0°) from 15° to 80°. Impregnation is carried out in a resin transfer mold. The temperature of the resin tank and impregnation mold can be maintained between room temperature and 80° C., the injection pressure can be 60-80 psi, and the injection volume can be 40-120 ml per stroke. Under these conditions, 1
Impregnation speeds of ~3 m/min are obtained. The viscosity of the resin is
200-10000cps, preferably 500cps. The product obtained according to the invention is a prepreg-like intermediate material. This material can be stored and later cured into the desired shape. The fibers of this product are well-arranged and fully impregnated and can be used in a variety of structural products such as tennis rackets,
Can be widely used in manufacturing badminton rackets and golf clubs. Hereinafter, the present invention will be explained in more detail with reference to Examples. It should be noted that these examples are merely non-limiting examples for illustrating the method of the present invention. All parts given in these examples are by weight unless otherwise indicated. Example 1 Epoxy resin (e.g. Epon828 from Shell, USA)
100 parts and a hardening agent (e.g. American Cyanamid)
DICY) and 0.5 parts of an amine type accelerator (eg BDMA from Ciba, USA) are placed in separate storage tanks. A multi-layer braiding machine (32 take-up reels, 16 axial take-up reels) was used to prepare carbon fibers (commercially available length
A bilayer braid of 12K fibers) is fabricated on an expandable cellophane tube. The braiding speed is 2 m/min. This braided body has a diameter of 30 cm, and the braiding angles of the rovings are ±30° and ±40° (assuming the axial fiber at the center of each layer is 0°). This braided body is pulled by a drive roll and sent to an impregnation mold at a temperature of 60°C. At the same time, the resin and curing agent are mixed and transferred by injection into the cavity of the impregnating mold.
Injection pressure is 80psi, injection volume per stroke
It is 80ml. This braided fiber is then impregnated with resin at a speed of 1.5 m/min. Once it has been completely made into prepreg, it is ironed using an ironing plate to obtain prepreg. This prepreg was cut to a length of 1.7 m, placed in a tennis racket molding die, heated at a temperature of 150°C,
A pressure of up to Kgf/cm ² is applied to the expandable cellophane tube by means of heated air. After maintaining the temperature and pressure for about 30 minutes, a tennis racket is formed. Example 2 Similar to Example 1, but using 48 take-up reels instead of 32, increasing the number of axial take-up reels to 24, and increasing the braid angle (the axial fibers in the center of each layer (as 0°) change to 45° and perform the operation. resin,
The conditions regarding carbon fibers and all operating steps are the same as in Example 1. The obtained prepreg was cut to a length of 0.65 m, passed through a cylindrical tube die, and heated at a temperature of 150°C by adding heated air to the inside of the expandable cellophane tube to create an internal pressure of 6 kgf/cm ² . Perform molding. Maintaining this condition for 30 minutes will yield a tube with a uniform outer diameter. Example 3 Using the same procedure and materials as Example 1, but using guide fibers (Asahi, Japan) instead of carbon fibers.
The operation is performed using a TEX 2310 (commercially available from Glass). Example 4 Carbon fiber (12K) was used instead of the carbon fiber in Example 1
The operation was carried out using an inter-hybrid of glass fiber and glass fiber (TEX2310 of Example 3), and other conditions were the same as in Example 1. The interhybrid means that the inner layer of the braided body is made of glass fiber and the surface layer is made of carbon fiber. Example 5 Carbon fiber (12K) was used instead of the carbon fiber in Example 1
The operation is carried out using an intra-hybrid of glass fiber (TEX2310 of Example 3) and other conditions are the same as in Example 1.
Said intrahybrid means that the axial fibers used are glass fibers and the diagonal cross fibers used are each 16 glass fibers and 16 carbon fibers. Example 6 Same conditions as Example 1, but instead of 12K
It uses 6K carbon fiber and operates with 48 reels instead of 32. Example 7 Prepreg braids are produced under the same conditions as in Example 1, but with different roving bias angles of 40°, 30° and 20°. Repeat the experiment six times at an angle of 40°. For an angle of 30°, the experiment is repeated four times, and for an angle of 20°, the experiment is repeated five times. All the obtained prepregs are directly molded and pressed to obtain samples. The physical properties of these samples
It was measured by the method of ASTM-D3039, and the data obtained are shown in Table 1. 【table】

[Brief explanation of the drawing]

Fig. 1 is a simplified illustration of the integrated manufacturing method of the present invention and the equipment used; Fig. 2 is a front view of a mold for receiving injected resin and impregnating fibers; and Fig. 3 is a front view of a mold for receiving injected resin and impregnating fibers. Figure 4 is a plan view of the apparatus for receiving injected resin and heating the mold for fiber impregnation; Figure 5 is a cross-sectional view showing the structure of the braided prepreg; It is a front view. 1... Core, 2... Carrier, 3... Fiber, 4
...Multilayer braiding machine, 5...Resin tank, 6...Curing agent tank, 7...Impregnation mold, 8...Release paper or film, 10...Ironing plate, 1
1... Press roller, 12... Chiller, 13...
... Drive roller, 14 ... Trimmer, 15 ... Winding device, 23 ... Heating plate.

Claims (1)

[Claims] 1. A continuous method for producing a single-layer or multi-layer braided fiber prepreg, comprising: (a) braiding a fiber roving onto an expandable tube using a multi-layer braiding machine; (c) a resin transfer molding machine injects a resin into the cavity of the mold to impregnate the braided fibers with the resin to produce a prepreg; (d) covering the prepreg fibers with a release paper or release film and then hot pressing with an ironing device to degas the prepreg and complete the impregnation; (e) finally cooling the braided fiber prepreg and Winding A manufacturing method consisting of successive operational steps. 2 The fiber braiding angle is 15° (assuming the axial direction is 0°)
80° and the fiber content is 40 to 50% by volume relative to the volume of the prepreg. 3 The fiber braiding angle is 30° (assuming the axial direction is 0°)
45° and the fiber content is 40 to 50% by volume relative to the volume of the prepreg. 4. According to claim 1, the inflatable tube is made of any polymeric material commonly used in the manufacture of tubes exhibiting elasticity, gas impermeability and heat resistance, such as cellophane, polypropylene, polyester or nylon. Manufacturing method described. 5. The method according to claim 1, wherein the braided prepreg can be single layer or multilayer. 6. The method according to claim 1, wherein the ironing device comprises a heating ironing plate and a press roller for applying gas under pressure. 7. The method according to claim 1, wherein the resin is selected from phenolic aldehyde resins, unsaturated polyester resins, epoxy resins, polyimide resins, and silicone resins. 8 The fiber is glass fiber, carbon fiber, Kevlar
The method according to claim 1, wherein the fibers are selected from fibers and any other fibers that can be used in composite materials. 9. The method according to claim 8, wherein the fiber roving is made of the same type of fiber or a hybrid of different types of fibers.