JPS621216Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improved prepreg used to obtain various molded products reinforced with carbon fibers.

Prepregs using carbon fibers have conventionally been produced in the form of nonwoven fabrics, yarns, crosses, short fibers, long fiber bundles aligned in one direction, or a combination of these carbon fibers with thermosetting properties. These prepregs are made by impregnating them with resin, but among these prepregs, prepregs in which carbon fibers are aligned in one direction can be easily made into sheets or tapes, so they can be used to make long tubular bodies, laminates, etc. It is suitable as a molding material and is widely used, for example, as a high-speed composite material for sports equipment such as golf club shafts, fishing rods, and ski bodies, and for automobiles and aircraft. Conventionally, this type of prepreg is made by impregnating resin into carbon fiber bundles made of multifilaments aligned in one direction, lining up multiple fiber bundles in the same direction so that each bundle is adjacent to each other, and applying tension to that state. The prepreg sheet can be obtained by cutting the prepreg sheets into various shapes and stacking them at various angles. It is a very complicated work as it has to be rolled up.

The present invention was developed as a result of various studies in view of the current situation, and has a special structure that can be used in products ranging from ultra-thin ones of 0.05 mm or less to extremely thick ones, which could not be obtained conventionally, and has a basis weight of 50 g/m ^2. The purpose is to provide a special prepreg that can be arbitrarily obtained up to a high basis weight, and its gist is to form a carbon fiber sheet-like material by forming an expanded carbon fiber aggregate into a sheet in a zigzag shape in this state. It is a prepreg impregnated with resin.

Next, the present invention will be explained in detail with reference to the drawings.

Figure 1 shows a conventional sheet made by applying tension to continuous carbon fiber bundles impregnated with resin and mechanically stretching the fiber bundles to spread them in the width direction. This is an enlarged sectional view showing a directionally aligned prepreg, in which at least several to several dozen individual carbon fibers 1 are held in a resin 2 in a laminated state in the thickness direction of the prepreg. This occurs because, as mentioned above, the fiber bundles are mechanically squeezed under a tension that does not break each single fiber, so there is insufficient force to move each single fiber in the lateral direction so as not to stack them. Therefore, it is impossible to make a prepreg with such a structure into an extremely thin sheet, and it is difficult to make a prepreg with high strength and low cost.

For this reason, it is currently difficult to obtain a prepreg with a thickness of 0.05 mm or less, and a fabric weight of 50 g/m ² or less.

FIG. 2 is an enlarged sectional view of an ultra-thin prepreg sheet representing an example of the present invention, and in the figure, individual single fibers 3 are held in a resin 4 in a nearly parallel state.
Therefore, it is possible to obtain prepregs that are extremely thin and have a minimum thickness almost equal to that immediately after the single fibers.

3 and 4 are plan views of the prepreg sheet of the present invention. The arcuate zigzag shape of each single fiber shown in FIG. 4 is more inclined than that shown in FIG. 3. In order to obtain the prepreg of the present invention, it is necessary to sufficiently open and uniformly spread the individual single fibers of a continuous carbon fiber bundle, which is difficult to do using conventional mechanical methods. For example, using a device such as that shown in JP-A-50-121568, a continuous carbon fiber bundle is fed into a liquid stream flowing down at high speed, and the fluid is spread out in a shape that widens as it goes downward. It can be obtained by splitting and expanding the carbon fibers by flow and letting them flow down along with the liquid flow onto a circulating open-hole conveyor, but at this time, the falling speed of the carbon fibers just before the open-hole conveyor is By setting an arbitrary speed higher than the circumferential speed of the perforated conveyor, it is possible to place the material on the perforated conveyor in an arbitrary zigzag shape. Therefore, the greater the ratio of the two speeds, the greater the inclination angle of the arcuate zigzag shape of the carbon fibers, and in extreme cases, the carbon fibers will be stacked at right angles to the traveling direction of the perforated conveyor. Therefore, by simply controlling the speed ratio between the two, it is possible to obtain an expanded carbon fiber aggregate sheet having an arbitrary inclination angle. The prepreg sheet shown in FIG. 4 described above is obtained when the speed ratio is larger than that shown in FIG. 3. In addition, the basis weight of the aggregate sheet itself can be made ultra-thin,
It is possible to easily obtain from the aggregate sheet with a low basis weight to the aggregate sheet with an extremely thick high basis weight.

Another feature of the present invention is that, as shown in Figures 3 and 4, it is a prepreg sheet in which each single fiber is arranged in a regular zigzag pattern. If it is laminated on the outer layer, a geometric pattern will be added to the appearance, which will have a significant design effect and increase the commercial value. In addition, golf club shafts conventionally required the cumbersome work of cutting unidirectionally aligned prepreg sheets into various shapes and wrapping them around a mold at a predetermined angle during the molding process, as described above. If a sheet is used, since the carbon fiber aggregate sheet is already arranged at an arbitrary inclination angle and is impregnated with resin, there is no need for any complicated cutting, and the work efficiency is significantly improved. In addition, in order to improve the crushing strength of fishing rods, if the prepreg sheet of the present invention having an appropriate inclination angle and a low basis weight is laminated on the conventional unidirectionally aligned prepreg sheet, the purpose can be fully achieved. , weight reduction will also be achieved, which will greatly contribute to the industry.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view showing a conventional unidirectionally aligned carbon fiber prepreg, FIG. 2 is an enlarged sectional view of an ultra-thin carbon fiber prepreg sheet showing an example of the present invention, and FIG. , FIG. 4 shows a plan view of the carbon fiber prepreg sheet of the present invention. 1, 3... Carbon fiber, 2, 4... Impregnated resin.

Claims (1)

[Scope of utility model registration request] A prepreg in which an expanded carbon fiber aggregate is formed into a sheet in a zigzag shape and is held in a resin.