JPH06155464A - Carbon fiber reinforced prepreg - Google Patents

Abstract

PURPOSE:To obtain a prepreg having excellent impact absorbing property for obtaining a tennis racket to which only a little vibration will be transmitted at hitting a ball by burying in layer a resin film having damping property when a carbon fiber reinforced prepreg is manufactured. CONSTITUTION:Carbon fibers are wound on a drum being impregnate with epoxy resin, cut off, and taken out from the drum. The fibers are folded such that carbon fiber angles become constant. A prepreg can be made by inserting a damping film when the fibers are folded. For a resin film having high damping property, polyisobutylene, polyisobutylene-isoprene copolymer are preferable. When a resin, for example, polyoctenamer is mixed in those, they are pelletized without lowering the damping property so much, and the film can be molded. It is desirable to provide adhesive layers on both faces of the damping film. A frame of a tennis racket can be obtained by winding the prepreg on a core and heating it in a mold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon fiber-reinforced prepreg and a tennis racket made from this prepreg.

[0002]

2. Description of the Related Art In recent years, the frame of a tennis racket has become lightweight and is mainly made of carbon fiber reinforced plastic (CRP) having both strength and rigidity. A tennis racket made of CRP has a characteristic that it is excellent in repulsing the tennis ball when hit. This carbon fiber reinforced plastic has a higher impact absorption than metal and is an excellent material from the viewpoint of reducing the impact vibration at the time of hitting a ball required for a recent tennis racket.

However, the tennis racket needs to have a higher impact absorption property, and for this reason, it is the practice at present to mount a rubber-like soft resin molded product between the gut. . Although this rubber-like soft resin molded product called a stabilizer has an effect of suppressing the vibration of the gut itself, it cannot reduce the vibration transmitted to the frame. Therefore, it is necessary to improve the shock absorbing performance of the frame itself.

In the present invention, as a result of extensive studies on the problems of the conventional tennis racket, a carbon fiber reinforced prepreg excellent in impact absorption was developed, and further, the propagation of vibration at the time of hitting was reduced by using the prepreg. It is intended to provide tennis rackets.

[0005]

That is, the present invention is a carbon fiber reinforced prepreg in which a resin film having a vibration damping property is embedded in layers, and a tennis racket using the prepreg.

The principle of the present invention is to absorb a vibration by encapsulating a resin film having a vibration damping property and converting the vibration energy into heat energy. As the resin film having high vibration damping property, a film having a glass transition point (Tg) near room temperature which is a use temperature is preferable, and polyisobutylene and polyisobutylene
The isoprene copolymer is excellent.

However, it is difficult to form a thin and easy-to-handle film with only these rubber compositions. Therefore, it is necessary to solve this problem by preparing plastics and resin compositions that are miscible with various rubbers. You can That is, it becomes possible to form a film by adding a small amount of a polyolefin represented by ethylene or propylene. However, the addition of such a polyolefin usually lowers the vibration-damping property of the film, so that its selection should be done with caution. For example, by mixing with a resin such as polyoctenamer, it is possible to make a vibration-damping resin with little reduction in vibration-damping property, which can be pelletized.
The use of such resins is preferred. The polyoctenamer referred to here is a resin having a regular primary structure obtained by ring-opening polymerization of cyclooctene, for example. Such resins include, for example, polyoctenamer commercially available under the trademark "Vestenamer" from Huls.
It can be used.

The vibration-damping resin film used in the present invention is
The thickness is preferably 30 μm to 300 μm, and 3
When it is thinner than 0 μm, the effect of damping property is not sufficiently exhibited, and even when it is thicker than 300 μm, the effect of damping property reaches a certain value, and the effect is not increased as much as the thickness.
On the contrary, if the thickness is more than 300 μm, the mechanical strength of the carbon fiber reinforced prepreg is lowered, which is not preferable.

The carbon fiber reinforced prepreg of the present invention is manufactured as follows. First, the carbon fiber is wound around a drum while being impregnated with an epoxy resin, cut at a constant angle with respect to the winding direction of the drum, and then removed from the drum. After the removal, the cloth-like epoxy resin-impregnated carbon fiber is repeatedly folded so that the carbon fiber angle is constant, and this is molded into a constant shape to form a prepreg. The vibration-damping carbon fiber-reinforced prepreg of the present invention can be made by inserting a vibration-damping film between the epoxy resin-impregnated carbon fiber layers in the folding step in the manufacturing process. The damping film may be inserted as a single sheet or may be inserted over multiple layers. At this time, if the affinity between the epoxy resin and the vibration damping film is insufficient, cracks occur between the cured epoxy resin and the vibration damping film, not only the vibration damping property is not exhibited, but also the mechanical strength is not exerted. Will be significantly reduced.

Since polyisobutylene and polyisoprene-polyisobutylene copolymer generally do not have very high affinity with epoxy resin, it is preferable to provide adhesive layers on both sides of the vibration damping film. This adhesive layer preferably has an affinity for both the vibration damping layer and the epoxy resin,
A suitable thickness is 5 to 30 μm. Preferred examples of the adhesive layer include polyolefins having a polar group introduced, such as epoxy-modified polyethylene, acrylic ester-modified polyethylene, and ethylene-vinyl alcohol copolymer. The three-layer film including the adhesive layer and the vibration damping layer can be produced by coextrusion and a multilayer inflation method. With this three-layer film, it becomes possible to impart damping properties without reducing the strength of the carbon fiber prepreg.

In the frame of the tennis racket of the present invention, the prepreg made as described above is wound on the core,
It can be obtained by heating in a mold. The above prepreg may be used for all parts of the tennis racket, or may be used for only part thereof. Further, the tennis ras racket of the present invention has characteristics of the carbon fiber reinforced composite material when applied to a "large size" having a hitting surface of 500 cm ² or more and a so-called "thick racket" having a thick frame. Is preferable. Recently, the weight has been reduced to 300
A racket having a weight of g or less is also used, and such a racket is particularly preferable because the vibration-damping prepreg of the present invention effectively acts and does not transmit an unpleasant vibration to the arm.

[0012]

EFFECT OF THE INVENTION By using the carbon fiber reinforced prepreg of the present invention, it is possible to manufacture a tennis racket which receives a small impact when hit. The carbon fiber reinforced prepreg of the present invention can be used in a wide range of fields such as a tennis racket, various sports equipment which should be light-weight and should absorb vibrations, automobiles, aircraft parts, electronic devices and the like.

[0013]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Preparation of damping film 40 parts by weight of polyisobutylene (MML-80 manufactured by Exxon), polyoctenamer (bestenamer 8 manufactured by Huls)
0-12) 20 parts by weight, ethylene-ethyl acrylate copolymer (Lexron A-3100 manufactured by Exxon) 10
Parts by weight were melt mixed and pelletized. A vibration-damping film was prepared by a multilayer inflation method such that epoxy-modified polyethylene (Lexpearl manufactured by Nisseki Chemical Co., Ltd.) was sandwiched from both sides from the center of the vibration-damping resin pellet to form an adhesive layer.

Preparation of prepreg Carbon fiber was replaced with epoxy resin (DOW33 manufactured by Dow Chemical Co.).
While soaking in 1), it was wound around a drum so that the fiber direction was constant. After winding a certain amount, cut it from the drum, fold it so that the direction of the carbon fiber is 30 to 45 °, repeat this 14 times, and finally 160 cm × 6 c
It was cut into prepregs having a size of m. At the time of folding and folding, one piece of the above-mentioned vibration damping film was inserted so that it was almost in the center of the finished prepreg. For comparison, a prepreg without a damping film was also created. The damping performance of the prepreg was measured by the cantilever resonance method. The results are shown in Fig. 1. Compared to the prepreg without vibration damping film, the prepreg with vibration damping film has a higher loss coefficient in a wide temperature range, and it is clear that the vibration damping film works effectively in the carbon fiber reinforced prepreg. Is.

Production of Tennis Racket The prepreg prepared by the above method was placed in a tennis racket mold and heated at 150 ° C. for 15 minutes to obtain a racket frame. The grip portion, gut parts, and gut were attached to the obtained racket frame to complete a terrace racket. Bending test of racket 12
Bending strength of a tennis racket, which was 0 kg and was similarly prepared from a prepreg without a damping film 1
It was almost equivalent to 25 kg.

The tip portion (III) of the racket shown in FIG.
FIG. 3 shows the vibration absorption characteristics at the measurement point (I) when a 70 gg rigid body was dropped onto the racket, and FIG. 4 shows the vibration characteristics when the entire racket was vibrated.

From FIG. 3, by inserting the damping film,
It is clear from FIG. 4 that the vibration time is shorter than that of the racket in which the vibration-free film is not inserted, and that the vibration-damping film-inserted racket has reduced resonance vibration with respect to high-frequency vibration.

[Brief description of drawings]

FIG. 1 is a result of measuring loss factors of a carbon fiber reinforced prepreg containing a vibration damping film and a carbon fiber reinforced prepreg prepared under the same conditions at each temperature.

FIG. 2 is a diagram showing a rigid body drop point (III) and a measurement point (I) when a rigid body is dropped on a tennis racket and vibration is measured.

FIG. 3 is a diagram comparing the vibration absorption of a tennis racket by a rigid body drop test between a tennis racket with a damping film and a tennis racket without a damping film.

FIG. 4 is a diagram comparing the vibration characteristics when the entire tennis racket is vibrated, comparing a tennis racket made of a carbon fiber composite material with a damping film with a tennis racket made of a carbon fiber composite material made under the same conditions. Is.

Claims (4)

[Claims] 1. A carbon fiber reinforced prepreg in which a resin film having a vibration damping property is embedded in layers. 2. The carbon fiber reinforced prepreg according to claim 1, wherein the resin film having damping properties has a three-layer structure of a damping resin layer containing butyl rubber as a main component and an adhesive layer sandwiching the damping resin layer. 3. A tennis racket comprising a frame using the carbon fiber reinforced prepreg according to claim 1. 4. A tennis racket comprising a frame using the carbon fiber reinforced prepreg according to claim 2.