JPH0783777B2 - Racket frame - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a racket frame such as a tennis racket and a badminton racket.

2. Description of the Related Art In recent years, FRP using glass fiber or carbon fiber as a reinforcing fiber has been widely adopted for racket frames such as tennis rackets.

In these FRP rackets, it is preferable to use GFRP using glass fiber as a reinforcing fiber in order to reduce the impact on the hand during hitting and to improve the control of hitting. On the other hand, in order to maintain the strength and the elastic modulus, it is preferable to use CFRP using carbon fiber. Therefore, conventionally, according to the desired physical properties of the racket to be manufactured, the compounding ratio of these fibers is adjusted so that the material of the racket frame is compounded. In particular,
To give strength and elasticity to the racket frame,
It is necessary to use high-strength carbon fiber, and there are rackets that use boron fiber as a part,
These are pretty expensive rackets.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention An object of the present invention is to provide a racket frame which has a simple manufacturing process and which has strength and elasticity equal to or higher than those of conventional carbon fiber reinforced ones.

Means for Solving the Problems That is, the present invention provides a racket frame characterized in that oxynitride glass fibers are arranged as reinforcing fibers in the FRP outer shell strength layer of the frame.

Oxynitride glass, which is a glass fiber raw material used in the present invention, has a structure in which oxygen atoms of oxide glass are replaced by nitrogen, and the bond valence of nitrogen atoms is 3
Therefore, it has a higher elastic modulus than conventional glass. In the method for producing such oxynitride glass,
There are sol-gel method of hydrolyzing metal alkoxide and then dehydration condensation, melting method of melting metal oxide and metal nitride, N ₂ gas blowing method, NH ₃ gas treatment method of porous glass, etc. It is possible to obtain an elastic modulus of 12,500 kg / mm ² or more, which could not be achieved with the above glass fiber.

Oxynitride glass fibers used as reinforcing fibers in the present invention are Si13-24at%, Ca10-21at%, Mg0-5.2.
at%, Al0 to 15.1at%, N7.5 to 25at%, M0 to 5at% (M: Z
r, Sr, Ba, Y, Ce, Na, B, La, K, Ti) are preferred.

If the Si content is less than the above range, crystallization occurs and a glass state cannot be obtained. Also, if it is more than this range, the elastic modulus is
It decreases to 12500kg / mm ² or less.

Further, if the content of Ca is less than the above range, crystallization occurs, while if it exceeds this range, the elastic modulus decreases to 12500 kg / mm ² .

If the Mg content exceeds the above range, crystals will form.

Further, if the content of nitrogen is less than the above range, the effect of containing nitrogen is not exerted, and if it exceeds this range, crystallization occurs.

Oxynitride glass used in the present invention has strength,
From the viewpoint of the N ₂ content, it is preferable to manufacture by the melting method.
To obtain oxynitride glass by a melting method, a metal nitride is added to a metal oxide and melted at a high temperature.

Examples of metal oxides include SiO ₂ , CaO, MgO, Al ₂ O ₃ SrO,
Na ₂ O, K ₂ O, La ₂ O ₃ , Y ₂ O ₃ , ZrO ₂ , TiO ₂ , Na ₂ O, K ₂ O, Ba
O, B ₂ O _{3 and the} like.

Examples of metal nitrides include Si ₃ N ₄ and AlN.

To melt a mixture of these metal oxides and metal nitrides, use a heating furnace such as an electric furnace or an image furnace, and treat them in a nitrogen atmosphere at a temperature of 1400 to 1900 ° C and a heating rate of 10 to 800 ° C / min. To do.

The obtained glass is heated and melted at a temperature of 1100 to 1600 ° C. under a nitrogen atmosphere, and spun at a spinning speed of 20 to 3000 m / min to obtain continuous fibers.

The elastic modulus of the obtained glass fiber is 12500 to 18000 kg / mm ² ,
A tensile strength of 70 to 500 kg / mm ² can be obtained.

The fiber diameter of the glass fiber is preferably 3 to 150 μm. If the fiber diameter is smaller than this range, spinning is difficult, while if it exceeds this range, the strength is extremely reduced, which is not preferable.

In order to manufacture a racket frame using the oxynitride glass fiber as a reinforcing fiber, a sheet (prepreg) is formed by impregnating glass fiber and glass cloth made of oxynitride glass fiber with a thermosetting resin. Then, install this prepreg in the mold,
It is heat-cured at an appropriate temperature and molded. The oxynitride glass fibers are preferably arranged in the circumferential direction of the frame. Further, the oxynitride glass fiber or the carbon fiber may be arranged in a direction orthogonal to this or in a diagonal direction.

Further, as the thermosetting resin, unsaturated polyester resin,
Examples thereof include phenol resins and epoxy resins, and these may be used alone or in combination of two or more kinds. The mixing ratio of the oxynitride glass fiber in the prepreg is about 25 to 60%.

EXAMPLES Next, the present invention will be described more specifically by way of examples.

Production Example 1 SiO ₂ 20.0 mol%, CaO 40.8 mol%, MgO 12.0 mol%, Al ₂ O ₃ 1
4.4 mol% was mixed and melted in air at 1500 ° C. for 2 hours. After cooling the mixture, it was crushed to about 10 μm using a ball mill,
Si ₃ N ₄ 12.8 mol% was added, and the mixture was melted in nitrogen at 1750 ° C. for 30 minutes using a boron nitride crucible to obtain an oxynitride glass. The obtained glass was placed in a boron nitride crucible placed in a spinning device, and using a cylindrical carbon heating element whose periphery was kept warm by a heat insulating material, heated at 1380 ° C. in a nitrogen atmosphere, spun and wound into a winder. It was Continuous fibers having a diameter of about 15 μm were obtained at a spinning speed of 1500 m / min. The tensile modulus of elasticity of the obtained glass fiber was 12600 kg / mm ² .

Embodiment 1 FIG. 1 is a perspective view showing a specific example of the tennis racket frame of the present invention. Frame 1 as shown in FIG.
An elliptical frame hitting portion 2 that stretches a gut, a shaft portion 4 that is held by a player, and a neck portion 3 that connects the hitting portion 2 and the shaft portion 4 are integrally formed. FIG. 2 is a sectional view taken along the line AA ′ in FIG. 1. The core portion has a box-shaped sectional structure in which a core material 5 made of foamed synthetic resin is surrounded and surrounded by an FRP outer shell strength layer 6. As shown in FIG. 3, the FRP outer shell strength layer 6 is composed of roving or roving cloth 7 made of oxynitride glass fiber and oxynitride glass fiber (or carbon fiber) 8. That is, the fiber arrangement of the oxynitride glass fibers 7 is arranged along the frame circumferential direction X, and the oxynitride glass fibers (or carbon fibers) are arranged.
The fiber arrangement of No. 8 is arranged along the frame width direction and the hitting direction Y along the gut tension direction perpendicular to the fiber arrangement direction of the oxynitride glass fiber 7.

In the above examples, the fiber arrangement direction of the oxynitride glass fiber (or carbon fiber) 8 is most preferably completely parallel to the frame width direction and the ball striking direction, but a maximum of ± 45 °, preferably 30
It may be slanted at an angle of ° or less.

Advantageous Effects of Invention The racket frame of the present invention has the same strain as conventional glass fibers, and by using oxynitride glass fibers having a strength and elastic modulus of 1.5 to 2.0 times, it is possible for the hand to hit the ball. The impact is small and the ball is easy to control. Also, it has excellent strength and elastic modulus,
Moreover, a lightweight and inexpensive racket can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing a racket frame of the present invention, and FIG.
FIG. 3 is a sectional view taken along the line AA ', and FIG. 3 is an enlarged perspective view of a portion B in FIG. The main symbols in the figure are as follows. 5: Foam synthetic resin layer, 6: FRP outer shell strength layer, 7: Oxynitride glass fiber.

Claims (2)

[Claims] 1. A racket frame characterized in that oxynitride glass fibers are arranged as reinforcing fibers in the FRP outer strength layer of the frame. 2. The racket frame according to claim 1, wherein oxynitride glass fibers are arranged in the circumferential direction of the frame.