JPH03162874A - Racket - Google Patents

Abstract

PURPOSE:To suppress the impact and vibration at the time of hitting by mounting a vibration damping material having a specific coefft. of vibration loss at ordinary temp. in at least a part of the racket. CONSTITUTION:The vibration damping material is mounted to at least a part of the racket, i.e., a part of frame, shaft and grip parts. Particularly the racket mounted with the vibration damping material in the shaft part has the excellent effect of suppressing the impact and vibration. This vibration damping material has >=0.01 coefft. of vibration loss at ordinary temp. and is preferably a thermosetting resin material consisting of an epoxy resin and polyamide resin having the m. p. within the range from ordinary temp. to 100 deg.C and at least one kinds of inorg. fillers selected from graphite, ferrite and mica as its essential raw materials.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a racket, particularly a tennis racket, which significantly suppresses impact vibrations when hitting a ball and allows comfortable play.

(Prior Art) Frames of rackets, particularly tennis rackets, have traditionally been made of lightweight, strong and rigid materials. In other words, wood, aluminum alloy, fiber-reinforced synthetic resin (FRP)
) etc. are used. Although these materials inherently have relatively good vibration damping properties, they are not always sufficient in their ability to rapidly and effectively reduce impact vibrations when hitting a ball.

Additionally, "stabilizers" have been proposed and commercially available for the purpose of reducing and mitigating impact vibrations when hitting a ball.

This "stabilizer" is a rubber or soft synthetic resin molded product that is attached between the guts of the racket or crimped to the gut surface. this"
According to the "Stabilizer", it is quite effective in suppressing the vibration of the gut itself, but it does not suppress the vibration propagated from the gut to the frame by the function of the frame itself.

(Problem to be Solved by the Invention) In other words, in conventional rackets, impact vibrations when hitting a ball propagate to the frame, and propagate to the arms and elbows through the shaft and grip, accumulating fatigue in the mantle and elbows. This led to the result that Furthermore, if the ball is hit off the center of the gut surface (the so-called sweet spot), the player often experiences unpleasant vibrations or stiffness.

In view of the shortcomings of conventional rackets, the present invention seeks to provide a racket, especially a tennis racket, which can be played comfortably and which significantly suppresses impact vibrations when hitting a ball.

(Means for solving problems) The following measures will be taken to achieve the above objectives.

That is, in the racket of the present invention, at least a portion of the racket has a vibration loss coefficient of 0.0 at room temperature. Special benefits are given to those fitted with vibration damping material that is OL or higher.

(Function) The present invention prevents vibrations from propagating from the string by attaching a damping material having a specific vibration loss coefficient to at least a portion of the racket, that is, a portion of the frame portion, shaft portion, grip portion, etc. This has succeeded in suppressing impact vibrations extremely rapidly and effectively in the area.

Particularly, those in which the vibration distribution material is attached to the shaft portion are excellent in impact vibration suppression effects.

That is, the damping material used in the present invention has a vibration loss coefficient of 0.01 or more, preferably 0.02 at room temperature.
As described above, such a vibration-damping material has the characteristic of quickly and effectively damping impact vibrations when a ball is hit.

The above-mentioned vibration loss coefficient is measured as follows. That is, after pasting a 10 mm thick synthetic resin onto a 5 mm thick steel plate using a two-component epoxy adhesive, the adhesive was left for 24 hours to harden, and then the US military standard MT L was applied.
-Measure the vibration damping waveform according to P-22581 B,
Find the vibration loss coefficient (η) using the following formula.

a. DECAY RATI! ，
(+IB/see)= (F/N) 2 0 lo
g (A r / A2 :b, effective attenuation factor (EFF
ECTIYE DECAY RATE) D e (
d8/sec)=D. -DI]C. Critical damping rate (
PERCENT CRITICAL DAMPIN
G) C/Cc (%) = (183xDe)/F where, F: Natural frequency N2 of the sample bonded disk Number of calculated periods A,: Maximum amplitude in N A2: Minimum in N Amplitude D. = Attenuation factor DII of sample bonded disk: Attenuation factor of original disk d. Vibration loss coefficient (η) η= (C/C c) / 5 0 Such vibration damping materials are generally called vibration damping materials, such as polyethylene, vinyl chloride, ethylene vinyl acetate, etc. Synthetic resins, cork, asphalt, etc. as well as compositions thereof can be used.

Among such splittable materials, melting points range from room temperature to 100°C.
Epoxy resin with a melting point within the range of room temperature to 100℃
A resin material consisting of a thermosetting resin composition whose main raw materials are a polyamide resin and at least one inorganic filler selected from graphite, ferrite, and mica is preferably used. That is, the above-mentioned composition is
It has a high degree of processing freedom, is flexible and lightweight, and exhibits extremely excellent vibration damping effects.

For example, a thermosetting damping resin material made of such a composition may be attached to the racket frame, shaft 1, or grip in the form of putty, and then left at room temperature or heated to harden before being attached. Alternatively, a hardened plate (film) formed in advance using a molding machine can be attached.

The epoxy resin having a melting point within the range of room temperature to 100°C referred to in the above composition is a resin having at least two or more glycidyl ether groups, preferably two or more glycidyl ether groups.
Viscosity at 5°C is 1 to 300 voids, epoxy equivalent is 10
It is preferable to have a molecular weight of 0 to 500 and a molecular weight of 200 to 1000.

Specifically, for example, Epicote 828, 827, 83
4, 807 (manufactured by Yuka Ciel Chemical Co., Ltd.), etc. can be used.

In addition, as a polyamide resin whose melting point is within the range of room temperature to 100°C, preferably the viscosity at 25°C is 3 to 2.
000 poise and an amine value of 100 to 800 are suitable because they act effectively as a curing agent for epoxy resins and as an agent for imparting flexibility to the resin after curing. Specifically, for example, Tomide #225-X, #215-X, #22
5 (manufactured by Fuji Kasei Co., Ltd.), Versamide 930,
115 (manufactured by General Mills), Epon ■
15 (manufactured by Shell), etc. can be used.

Such polyamide resin acts as a curing agent for epoxy resins, but in order to shorten the curing time and sufficiently progress the curing of the molded product, it is recommended to use a curing agent for commonly used epoxy resins. can. Such curing agents include aliphatic amines such as triethyltetramine, propanolamine, aminoethylethanolamine, aromatic amines such as P-phenylenediamine, tris(dimethylamino)methylphenol, benzylmethylamine, and even phthalic anhydride. , a carboxylic acid such as maleic anhydride, and the like can be used. The amount of the curing agent to be added may be sufficient for curing, taking into consideration the epoxy equivalent, amine equivalent, and acid equivalent.

In addition, the inorganic fillers filled in these resins include graphite,
It is at least one selected from ferrite and mica. Among such inorganic fillers, graphite is preferably used because it has excellent impact vibration suppressing properties, and furthermore,
Among these, those having an aspect ratio of 3 to 70 are preferred. The aspect ratio is a value obtained by dividing the diameter of a graphite particle by its thickness, and those in the above range have excellent wettability with resin and excellent mixing characteristics.

The above portions are preferably blended in the following proportions.

That is, the blending amount of the polyamide resin with respect to 100 parts of the epoxy resin is 100 to 800 parts, more preferably 2 parts.
00 to 500 parts, and the inorganic filler is 30 to 120 parts, more preferably 40 to 100 parts, based on 100 parts of the total amount of these resins (including monoglycidyl ether, which will be described later). .

In addition, it is preferable to further blend a monoglycidyl ether compound into the above-mentioned resin composition, since it is possible to provide a damping resin material that is extremely flexible and has excellent processability. Particularly preferably, the epoxy equivalent is 80 to 400 and the molecular weight is 8.
A monoglycidyl ether compound having a molecular weight of 0 to 400 is preferable. Specifically, octadecyl glycidyl ether, phenyl glycidyl ether, butylphenyl glycidyl ether, etc. can be preferably used. Such a compound has the advantage that the viscosity of the resin composition can be adjusted to be extremely effective for use in the form of a putty.

The compounding amount of this compound is preferably 5 to 45 parts, more preferably 10 to 25 parts, per 100 parts of the epoxy resin.

When making a resin molded product (plate, film) from a resin composition consisting of the above-mentioned components, first the boxy-based component (
epoxy resin, monoglycidyl ether compound) and polyamide components (polyamide resin, curing agent, inorganic filler)
A method is used in which the two are mixed in separate systems, and then both are mixed together at the end. The above-mentioned method is also adopted when the resin composition is used in the form of a putty. In either case, it is preferable to use a mixer for high viscosity to mix gently and uniformly so as not to introduce air bubbles.

Curing of such a resin composition varies depending on the type of epoxy resin, curing agent, and polyamide resin used, but the curing temperature is between room temperature and
It can be cured and molded into a resin by coating or using a molding device into a desired shape under a temperature condition of 100°C.

The damping resin material thus obtained is attached to at least a portion of the racket, such as the frame, shaft, and grip. Mounting here means, for example, attaching a plate-shaped molded body made of the resin to the inside or at least part of the surface of the aggregate of the grip, or attaching a coating made of the resin to at least a part of the aggregate. It means attaching or covering with the resin, and bonding (adhering, fixing, laminating, coating) a lump made of the resin to at least a part of the frame, shaft, grip, etc. It is.

This mounting method will be further explained with reference to the drawings.

FIG. 1 shows an example of the racket of the present invention, and is a plan view of an example in which the vibration damping material 4 of the present invention is adhered to the front and back surfaces of a part of the shaft portion 3.

FIG. 2 shows another example of the racket of the present invention, in which the grip portion 2 is coated with a vibration-damping material 4 affixed thereto.

FIG. 3 shows an example in which the damping material 4 is attached to both the shaft 3 and the grip 2.

The racket used in the present invention is a general term for rackets with strings, such as squash rackets, tennis rackets, and badminton rackets.In particular, the racket of the present invention is suitable for rackets where the sweet spot is a problem, especially tennis rackets. suitable.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.

Examples 1 to 3, Comparative Examples 1 and 2 A vibration damping plate having a thickness of 10 mm was made using resin materials having different formulations shown in Table 1 as vibration damping materials. The vibration loss coefficient of this plate at a room temperature of 20° C. was measured by the method described above.

Furthermore, a damping plate with a thickness of 3mm made of the above-mentioned various damping materials was cut into a width of 5mm, and a reactive putty-like material was placed on the front and back of the racket shaft portion shown in Fig. 1 before being molded into a damping plate shape. After pasting it on the frame with something, at room temperature of 20℃,
For these rackets, a micro-acceleration pickup is attached to the center of the grip, the tip of the frame is tapped with a hammer, and the attenuated waveform of the vibration is measured using an FFT analyzer (
Ono Sokki (manufactured by Ono Sokki), the waveform was measured using a microcomputer (NEC @) using MIL-P-225811.
The vibration loss coefficient (η) was determined according to the formula in 1, and the results shown in Table 2 were obtained.

In Comparative Example 2, the vibration damping performance was obtained without applying a damping material to the racket shaft portion. Furthermore, Comparative Example 1 is an example in which the vibration loss coefficient is less than 0.01.

The feel at impact in Table 2 was determined by asking 20 tennis players to rate the feel of the ball when they hit it into the following three grades.

First, the participants were asked to hit a ball with a racket to which no damping material was attached (Comparative Example 2), and the feel of the ball at that time was rated △ (average) for comparison.

△: Fair, ○: Good, ◎: Very good As is clear from the results in Table 2, the rackets of the comparative examples all had low vibration loss coefficients and had a significantly worse shot feel than the rackets of the example. It was something.

It was found that the rackets of Examples {~3] exhibit better effects as the vibration loss coefficient of the damping material increases. It was also confirmed that the tendency of this effect was proportional to the amount of graphite filled, and Example 3, which was filled with the most amount of graphite, exhibited the most excellent vibration damping properties.

Examples 4 to 6, Comparative Examples 3 and 4 Using the damping materials of Examples 1 to 3 and Comparative Example 1, damping plates each having a thickness of 3 mm were created.

This vibration damping plate was cut so as to follow the surface from which the grip tape had been removed, and was attached to the entire surface of the grip using a two-component epoxy adhesive to create the racket shown in Figure 2.

These rackets were measured using the same evaluation method as in Example 1, and the results shown in Table 3 were obtained.

As is clear from Table 3, the tendency of the damping effect is that of Example 1.
- 3. It was similar to Comparative Example t, but the vibration damping effect was slightly different depending on the attachment position, and compared to Examples 1 to 3, Examples 4 to 6 had a slightly lower vibration damping effect. The loss coefficient was low. In particular, in the case of Example 5, the shot feel was ◎ to ◎ at the position of Example 2, but it decreased to 0.

Examples 7 to 9, Comparative Examples 5 and 6 Similarly to Examples 4 to 6, damping plates each having a thickness of 5 m+a were created using the damping materials of Examples 1 to 3 and Comparative Example 1. This damping plate was attached to the shaft portion using a two-component epoxy adhesive, and the damping plate was also cut and attached to the entire surface of the grip to form the racket shown in FIG. 3.

These rackets were measured in the same manner as in Examples t to 3, and the results shown in Table 4 were obtained.

As is clear from Table 4, it has been confirmed that when damping material is attached to the shaft and grip, it has a greater damping effect than when it is attached to each part. Ta.

(Effects of the Invention) The present invention provides a racket that has a function of extremely well damping the transmission of impact vibrations from the gut to the frame, shaft, and grip when a ball is hit.

According to this racket, there is no unpleasant vibration or tingling when a ball is hit with a part that is outside the sweet spot of a conventional racket, and it also satisfactorily reduces the fatigue of the arms and elbows caused by impact vibrations, so the wrists, arms, and elbows are not affected. You can play comfortably and accurately without accumulating fatigue.

[Brief explanation of the drawing]

Figures 1 to 3 are schematic model diagrams showing embodiments of the racket of the present invention, and Figure 1 is an example in which the damping material of the present invention is attached to the shaft portion. , FIG. 2 shows an example in which the distributable material is attached to the grip part, and FIG.
This is an example in which the damping material is attached to both the shaft portion and the grip portion. 1: Frame 2: Grip 3: Shaft 4 2. Vibration damping material

Claims (3)

[Claims] (1) A racket characterized in that at least a portion of the racket is equipped with a damping material having a vibration loss coefficient of 0.01 or more at room temperature. (2) The racket according to claim 1, wherein the vibration damping material has a vibration loss coefficient of 0.02 or more. (3) The damping material is at least one selected from epoxy resin with a melting point within the range of room temperature to 100°C, polyamide resin with a melting point within the range of room temperature to 100°C, and graphite, ferrite, and mica. The racket according to claim 1, which is a thermosetting product whose main raw material is a seed inorganic filler.