JP3519350B2 - Racket frame - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a racket frame which is formed of a molded article having a fiber reinforced resin layer and is used in ball games such as hard tennis and soft tennis. And it can be improved in an appropriate way.

[0002]

2. Description of the Related Art Bamboo, light metal, etc. have been used for hard tennis rackets for a long time, but in recent years, fiber reinforced resin has become the mainstream. Since the fiber reinforced resin has a high specific strength, the weight of the tennis racket can be reduced while maintaining the strength. The tennis racket made of fiber reinforced resin is also suitable for mass production.

When a player hits a ball with a tennis racket, the tennis racket vibrates. This vibration is transmitted to the player's human body through the grip and makes the player uncomfortable. Vibration is also considered to be the cause of so-called tennis elbows. In particular, when the ball is hit on a portion of the hitting surface other than the sweet spot, violent vibration is generated, which causes great damage to the player.

The above-mentioned tennis racket made of fiber reinforced resin is superior in vibration damping property to a tennis racket made of metal, but even this tennis racket made of fiber reinforced resin is not sufficient in vibration damping property. The problems such as tennis elbow have not been completely resolved. Moreover, in recent years, the strength and elasticity of the fibers have been increased to further reduce the weight of the tennis racket made of the fiber reinforced resin, but there is a tendency that the vibration damping property is deteriorated along with the weight reduction. . Even in a tennis racket made of fiber reinforced resin, a sufficient improvement in vibration damping is desired.

Japanese Unexamined Patent Publication No. 10-337812 discloses a tennis racket in which an ionomer resin film is interposed in a fiber reinforced resin laminate having an epoxy resin as a matrix. Since the ionomer resin has a better vibration damping property than the epoxy resin, the vibration damping property of the tennis racket is improved by interposing the ionomer resin film.

[0006]

However, even with a tennis racket having an ionomer resin film interposed, the vibration damping property is still insufficient. Further, since the ionomer resin has poor adhesion to the epoxy resin, the ionomer resin film may be peeled off by repeated impacts. When peeling occurs, the strength of the tennis racket decreases. In reality, there is a demand for a tennis racket that has a sufficiently high vibration damping property and is resistant to delamination.

[0007] Therefore, the applicant of the present application has found that the loss coefficient (tan
A racket frame in which a molded product made of a viscoelastic material having a δ) of 1.0 or more is interposed in a fiber reinforced resin layer is disclosed in Japanese Patent Application No. 11-1.
It was previously proposed as No. 66226. However, Japanese Patent Application 1
In the case of the racket frame proposed by No. 1-166226, there is still room for improvement in that it is difficult to improve the vibration damping property in a sufficient and appropriate manner. That is, although the vibration damping property is improved by inserting the viscoelastic material, the racket tends to be heavy and difficult to swing due to the increase in weight.
The decrease in strength due to the inclusion of the viscoelastic material cannot be ignored.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a racket frame which can improve the vibration damping property in a sufficient and appropriate manner.

[0009]

In order to solve the above-mentioned problems, the present invention is a racket frame comprising a molded body in which a plurality of fiber-reinforced resin layers made of fiber-reinforced prepreg are laminated. At least part of the layers has a loss factor (t
an δ) is 1.0 or more and 3.0 or less, and the temperature rise temperature is 10 ° C /
A racket frame characterized by having a softening point of 80 ° C. or higher in a min DSC test and inserting a viscoelastic material having a thickness of 0.1 mm or more and 0.6 mm or less as a vibration absorber. is doing.

In the racket frame of the present invention, the viscoelastic material as a vibration absorber interposed in the fiber reinforced resin layer has a loss coefficient (tan δ) of 1.0 or more under the conditions of a frequency of 10 Hz and a temperature of 6 ° C. and 0. Since it has a thickness of 1 mm or more, the vibration absorption is sufficiently enhanced. Moreover, since the thickness of the viscoelastic material is not as thick as 0.6 mm or less, it is possible to avoid the presence of excessive volume between the layers of the fiber reinforced resin layer, and it is not necessary to increase the weight so that the racket becomes difficult to swing. It is possible to suppress the decrease in strength due to the interposition of the viscoelastic material.

The loss coefficient (tan δ) of the viscoelastic material is 1.0
If it is less than 1.0, it is impossible to exert a necessary vibration damping effect with a viscoelastic material having a thickness of 0.6 mm or less. From this viewpoint, the loss coefficient (tan δ) is preferably 1.2 or more, more preferably 1.5 or more. Loss factor (tan
Since the larger the δ) is, the higher the vibration damping property is, the upper limit of the loss coefficient (tan δ) does not have to be particularly specified in the present invention. tan δ) is 3.0 or less,
In particular, 2.0 or less is preferable.

The loss coefficient (tan δ) of the viscoelastic material is measured by a viscoelasticity measuring device (Viscoelasticity spectrometer “DVA200 improved type” manufactured by Shimadzu Corporation). The measurement conditions include a frequency of 10 Hz, a temperature of 6 ° C., a jig being pulled, a temperature rising rate of 2 ° C./min, an initial strain of 2 mm, and a displacement amplitude of plus or minus 12.5.
μm. The width of the test piece (dumbbell) is 4.0.
mm, the thickness is 1.66 mm, and the length is 30.
It is 0 mm. Since both ends of the test piece are chucked by 5 mm, the length of the displaced portion of the test piece is 20.0 mm. In addition, as the viscoelastic material for the vibration absorber, one having a softening point of 80 ° C. or higher, preferably 100 ° C. or higher, particularly preferably 140 ° C. or higher in a DSC test at a temperature rising rate of 10 ° C./min can be mentioned. To be If the softening point is low, it will easily flow during the heat forming process. An example of such a viscoelastic material is a dipole gee film (softening point 150 ° C.) manufactured by CCI.

If the thickness of the viscoelastic material is 0.1 mm or less, it is difficult to improve the vibration damping property as much as necessary, so the thickness is set to 0.1 mm or more. Thickness is 0.6m
If it exceeds m, the weight of the viscoelastic material with respect to the weight of the racket frame becomes too large, making it difficult to swing, and the decrease in strength cannot be ignored, and further improvement in vibration damping cannot be expected. Is 0.6m
m or less.

In the racket frame of the present invention, the fiber reinforced resin layer is formed by laminating a plurality of fiber reinforced prepregs, and the viscoelastic material for the vibration absorber is inserted between the layers of the fiber reinforced resin layer. The preferred form is
This prevents the viscoelastic material from coming off. However, the viscoelastic material may be embedded not in the fiber-reinforced resin layer but in the layer.

Further, when only one viscoelastic material is interposed in the fiber reinforced resin layer, the thickness of the viscoelastic material is 0.2 mm.
It is preferably 0.6 mm or more and 0.6 mm or less. Further, when at least two viscoelastic materials are interposed so as to be in a laminated state with the fiber reinforced prepreg sandwiched, each viscoelastic material has a thickness of 0.1 mm or more and 0.4 mm or less, preferably 0.1 mm or more and 0 mm or less. It is preferably thinner than 0.3 mm. By virtue of the plurality of viscoelastic materials, it is possible to have sufficient contact with each movement of the vibration that is performing complex movements such as twisting, shearing, and compression, so that the vibration damping property is further enhanced. Further, if the viscoelastic material is thin, it is easy to suppress an increase in weight even if a plurality of viscoelastic materials are inserted.

When a viscoelastic material is inserted near the center of the thickness of the fiber reinforced resin layer, the vibration damping property becomes excellent. It is considered that if the viscoelastic material intervenes so as to divide the fiber reinforced resin layer as evenly as possible in the thickness direction, the vibration damping action of the viscoelastic material can be sufficiently exhibited. That is, assuming that the total thickness of the fiber-reinforced resin layer is 100%, 20 from the thickness center to one side (outside) and the other side (inside) in the thickness direction.
When at least one viscoelastic material, preferably 50% or more of the viscoelastic material, is interposed in the thickness range of 10% or less, preferably 10% or less, the vibration damping property is further enhanced.

In order to set the loss coefficient (tan δ) of the viscoelastic material to 1.0 or more as described above, a polymer having a large loss coefficient (tan δ) itself (for example, chlorinated polyethylene) is used as a main polymer of the viscoelastic material. Etc.) may be used.
Moreover, even if the loss coefficient (tan δ) of itself is not so large, by adding a softening agent such as oil to this polymer (for example, by adding a large amount of oil to polynorbornene), the loss coefficient A viscoelastic material having a (tan δ) of 1.0 or more can be obtained. On the other hand, it is preferable that the viscoelastic material has good adhesiveness to the matrix resin in the fiber reinforced resin layer, because peeling of the viscoelastic material is suppressed. In the case of a fiber-reinforced resin layer in which the matrix resin is an epoxy resin, a viscoelastic material made of chlorinated polyethylene is suitable because it has excellent adhesion. Specific examples thereof include CIP's dipole film (chlorinated polyethylene film) and Tosoh's Elastage ED series (ester-based polymer, halogen-based polymer alloy material). By the way, the loss factor (tan δ) of the dipole gee film is 1.3, and the loss factor (tan δ) of the elastage ED series is 1.1.

In general, a racket frame has a head portion forming the contour of a ball striking face, and two throat portions extending from the head portion and joining each other at one end (and a shaft portion and a grip portion following the throat portion). And the top position is 12 o'clock with the ball striking face as the watch face, the first position in the range of 11 o'clock to 1 o'clock and 3 o'clock to 5 o'clock (7 o'clock to 9 o'clock).
It is preferable to dispose the viscoelastic material at one location or two or more locations selected from the second position in the range of the hour) and the third position of the left and right throat portions. By arranging the viscoelastic material at the first position, the second position and the third position, the vibration damping property can be sufficiently enhanced. However, if there is only one location of viscoelastic material (especially the first position), the balance will be large and the weight feeling when holding the racket will be large, so at that time, there are more viscoelastic materials than two locations. The balance can be reduced by arranging dispersedly.

Further, in the case of the racket frame of the present invention,
Racket frame weight without string is 2
The balance is preferably 50 g or less and the balance is 380 mm or less. Usually, the racket frame weighs less than 250g,
While the racket having a balance of 380 mm or less is a light racket that is easy to swing with a top heavy, the vibration damping property tends to be insufficient, but this difficulty is overcome in the racket frame of the present invention by proper interposition of a viscoelastic material. It will be.

Further, in the case of the racket frame of the present invention, the weight of the viscoelastic material is the weight of the racket frame (low frame weight) without coating and without strings and parts (grip tape, end caps, bumpers, grommets, etc.). Of 0.5% or more and 3.0% or less is preferable. If it is less than 0.5%, it is difficult to obtain the necessary vibration damping property, and if it exceeds 3.0%, the racket frame tends to be too heavy.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view showing a racket frame according to the embodiment.

The racket frame 1 shown in FIG. 1 has a head portion 2, two throat portions 3, a shaft portion 4 and a grip portion 5.
And a yoke 6. The head portion 2 forms the contour of a ball striking face, and its cross-sectional shape is substantially elliptical. Each of the two throat portions 3 has one end extending from the head portion 2 and the other end joining each other. The shaft portion 4 extends from the portion where the throat portion 3 joins, and the throat portion 3
Is formed continuously and integrally. Grip part 5
Is formed continuously and integrally with the shaft portion 4. A portion of the head portion 2 sandwiched by the throat portions 3 and 3 is a yoke 6. The racket frame 1 is hollow because it is composed of a molded product having a fiber-reinforced resin layer in which the matrix resin is an epoxy resin and the reinforcing fibers are carbon fibers. A string is stretched on the racket frame 1, and a grip tape, an end cap, and the like are attached to the racket frame 1 to form a racket for hard tennis.

As shown in FIG. 2, the racket frame 1 has the first positions 11 and 3 in the range from 11:00 to 1:00 when the top position is 12 o'clock when the striking face is viewed as a clock face.
As shown in FIG. 3, at one or more positions selected from the second position 12 and the third position 13 of the left and right throat parts in the range of hours to 5 (7 to 9), as shown in FIG. As a preferable structure, the viscoelastic material 9 is arranged so as to be interposed in the fiber reinforced resin layer 10, but the viscoelastic material 9 is used as the grip portion 5.
It can also be arranged on the yoke 6. Further, the fiber reinforced resin layer 10 of the racket frame 1 is, as shown in FIG.
It is formed by winding many epoxy resin prepregs around the mandrel. By removing the mandrel, a hollow portion is formed, and a plurality of fiber reinforced prepregs 10-1 to 10-8 are laminated. Then, the viscoelastic material 9 is inserted into an appropriate place among the layers of the fiber reinforced prepregs 10-1 to 10-8.

The viscoelastic material 9 for the vibration absorber is, for example, chlorinated polyethylene or polynorbornene mixed with a large amount of oil, and has a loss coefficient (tan δ) at a frequency of 10 Hz and a temperature of 6 ° C. Is 1.0 or more, preferably 1.2 or more, more preferably 1.5 or more, and
A softening point of 80 ° C. or higher, preferably 100 ° C. or higher, particularly 140 ° C. or higher is used. As a concrete example of the suitable viscoelastic material 9, for example, a dipole gee film (loss coefficient (tan δ) 1.3, softening point 1 manufactured by CCI) is used.
50 ° C.).

Further, the viscoelastic material 9 has a thickness of 0.1 mm.
It is in the form of a sheet having a range of not less than 0.6 mm. Although not limited to a sheet shape, when the viscoelastic material 9 is inserted between the layers of the fiber reinforced resin layer, the viscoelastic material is preferably a sheet shape from the viewpoint of easy production. The volume of the viscoelastic material 9 is preferably 0.5 cm ³ or more and 6 cm ³ or less. If the volume is too small, it is difficult to obtain the necessary vibration damping effect, and if the volume is too large, it becomes difficult to interpose it.

In order to insert and interpose the viscoelastic material 9 for the vibration absorber between the layers of the fiber reinforced prepregs 10-1 to 10-8, when a plurality of prepreg sheets are wound around the mandrel, the viscoelastic material 9 is laid between the prepreg sheets. The elastic material 9 may be inserted. Further, when the viscoelastic material 9 is interposed only between one layer, the thickness of the viscoelastic material may be 0.2 mm or more in order to secure the necessary vibration damping property. Further, when at least two viscoelastic materials 9 are interposed so as to be in a laminated state with one layer or a plurality of layers of the fiber reinforced prepregs 10-1 to 10-8 interposed, each viscoelastic material 9 has a thickness of 0. ．
The thickness may be 4 mm or less, preferably 0.3 mm or less. When the viscoelastic material 9 is thin, the increase in weight can be suppressed even if a plurality of viscoelastic materials 9 are inserted.

When the viscoelastic material 9 is inserted near the center of the wall thickness of the fiber reinforced resin layer 10 of the racket frame 1, the vibration damping property is excellent. It is considered that the viscoelastic material 9 inserted so as to divide the fiber-reinforced resin layer 10 in the thickness direction as evenly as possible can effectively exhibit the vibration damping effect. That is, as shown in FIG. 4, assuming that the total thickness d of the fiber-reinforced resin layer 10 of the racket frame is 100%, the thickness center d
From 1 to one side (outside) and the other side (inside) in the thickness direction within 20% (between d2 and d3), preferably 10%
It is preferable that at least one viscoelastic material 9 and 50% or more of the viscoelastic material 9 intervene in the thickness range within (between d4 and d5) to enhance the vibration damping property.

Further, in the case of the racket frame 1, the weight of the racket frame 1 without strings is 250.
It has a balance of g or less and a balance of 380 mm or less, and in addition to having sufficient vibration damping properties, it is a racket that is light and easy to swing for a top heavy. Further, in the case of the racket frame 1, the weight of the viscoelastic material 9 is 0.5 of the weight (low frame weight) of the racket frame in a state where unpainted strings and parts (grip tape, end caps, bumpers, grommets, etc.) are not present. % And 3.0% or less, the racket frame 1 is prevented from being too heavy due to the presence of the viscoelastic material 9.

Then, in order to evaluate the performance and the like of the racket frame 1 of the above-described embodiment, the following examples were prepared and also comparative examples were prepared.

Example 1 A sheet of fiber reinforced prepreg in which the matrix is an epoxy resin and the reinforcing fibers are carbon fibers is wound around a mandrel, and a length of 8 is obtained.
cm, width 6 cm, thickness 0.1 mm dipole gee film made by CCI was inserted as a viscoelastic material 9 for a vibration absorber. The number of the viscoelastic material 9 inserted is one, and the insertion site is the third position 13 of the left and right throat portions 3. Further, the weight of the viscoelastic material, the number of laminated prepregs, the interlayer position where the viscoelastic material 9 is laminated (the viscoelastic material laminating position), the weight ratio of the viscoelastic material 9 to the low frame weight (viscoelastic material weight%), fiber Insertion position of viscoelastic material 9 when the total thickness d of the reinforced resin layer 10 is 100% and the thickness center d1 is the reference point (position% in the thickness direction)
Are as shown in Tables 2 to 4. Regarding the position% in the thickness direction, the outermost position is + 50% and the innermost position is -50%, with the position of the thickness center d1 being 0%. After removing the mandrel, the molded body was heated in the mold to obtain the racket frame of Example 1. The racket frame weighed 241.2 g and had a body balance of 360 mm.

Example 2 A racket frame of Example 2 was obtained in the same manner as in Example 1 except that the thickness of the dipole energy film was 0.2 mm. (Example 3) The thickness of the dipole energy film is 0.4 m.
A racket frame of Example 3 was obtained in the same manner as in Example 1 except that m was set. (Example 4) The thickness of the dipole energy film is 0.6 m.
A racket frame of Example 4 was obtained in the same manner as in Example 1 except that m was set.

Comparative Example 1 A racket frame of Comparative Example 1 was obtained in the same manner as in Example 1 except that no dipole energy film was inserted. (Comparative Example 2) The thickness of the dipole energy film is 0.0
A racket frame of Comparative Example 2 was obtained in the same manner as in Example 1 except that the racket frame was 5 mm. (Comparative Example 3) The thickness of the dipole energy film is 1.0.
A racket frame of Comparative Example 3 was obtained in the same manner as in Example 1 except that the racket frame size was mm. (Comparative Example 4) The thickness of the dipole energy film is 1.2.
A racket frame of Comparative Example 4 was obtained in the same manner as in Example 1 except that the racket frame was mm.

(Example 5) A racket frame of Example 5 was obtained in the same manner as in Example 2 except that the number of dipole film was two. (Example 6) A racket frame of Example 6 was obtained in the same manner as in Example 2 except that the number of dipole energy films was three. (Example 7) A racket frame of Example 7 was obtained in the same manner as in Example 2 except that the number of dipole energy films was four. (Example 8) The number of dipole energy films is 1.5.
A racket frame of Example 8 was obtained in the same manner as in Example 3 except that the racket frame was one (half the size of the other).

Comparative Example 5 An ionomer resin having a loss coefficient (tan δ) of 0.1 under the conditions of a frequency of 10 Hz and a temperature of 6 ° C. instead of the dipole energy film (trade name “Hilamin 165 manufactured by DuPont Mitsui Polychemical Co., Ltd.”
A racket frame of Comparative Example 5 was obtained in the same manner as in Example 6 except that the sheet of "2") was used.

(Embodiment 9) The insertion position of the viscoelastic material 9 is the first position (top) 1 in the range from 11:00 to 1:00 of the head portion 2.
A racket frame of Example 9 was obtained in the same manner as in Example 6 except that the racket frame was No. 1. (Example 10) Except that the insertion site of the viscoelastic material 9 is the second position 12 at 3 o'clock (9 o'clock) in the range of 3 o'clock to 5 o'clock (7 o'clock to 9 o'clock) of the head part 2. A racket frame of Example 10 was obtained in the same manner as in Example 6. (Example 11) Except that the insertion portion of the viscoelastic material 9 is the second position 12 at 4 o'clock (8 o'clock) in the range of 3 o'clock to 5 o'clock (7 o'clock to 9 o'clock) of the head part 2. A racket frame of Example 11 was obtained in the same manner as in Example 6. (Example 12) A racket frame of Example 12 was obtained in the same manner as in Example 6 except that the insertion portion of the viscoelastic material 9 was the yoke 6. (Example 13) The insertion portion of the viscoelastic material 9 is the grip portion 6.
A racket frame of Example 13 was obtained in the same manner as in Example 6 except for the above.

Example 14 The insertion site of the viscoelastic material 9 is
The first position (top) of the head portion 2 in the range from 11:00 to 1:00
11 and the second position 1 in the range from 3 o'clock to 5 o'clock (7 o'clock to 9 o'clock)
Example 14 in the same manner as in Example 6 except that the viscoelastic material 9 is half the size and the position is 2 o'clock at 4 o'clock (8 o'clock).
Got a racket frame. (Example 15) The insertion sites of the viscoelastic material 9 are the first position (top) 11 in the range from 11:00 to 1:00 of the head part 2 and the third position 13 of the left and right throat parts 3, and A racket frame of Example 15 was obtained in the same manner as in Example 6 except that the size of the viscoelastic material 9 was half. (Example 16) The insertion position of the viscoelastic material 9 is the second position 12 at 4 o'clock (8 o'clock) in the range of 3 o'clock to 5 o'clock (7 o'clock to 9 o'clock) of the head portion 2 and the left and right throats. A racket frame of Example 16 was obtained in the same manner as in Example 6 except that the viscoelastic material 9 was half the size of the third position 13 of the portion 3.

(Example 17) The laminated position of the viscoelastic material 9 was
A racket frame of Example 17 was obtained in the same manner as in Example 2 except that it was between the layers of the fiber reinforced prepregs 10-1 and 10-2. (Example 18) A racket frame of Example 18 was obtained in the same manner as in Example 2 except that the laminating position of the viscoelastic material 9 was between the layers of the fiber reinforced prepregs 10-4 and 10-5. (Example 19) A racket frame of Example 19 was obtained in the same manner as in Example 2 except that the laminating position of the viscoelastic material 9 was between the layers of the fiber reinforced prepregs 10-7 and 10-8.

(Evaluation Test) Various evaluation tests were carried out on the above-mentioned Examples and Comparative Examples according to the methods described below.

(Adhesion Evaluation Test between Viscoelastic Material and Fiber Reinforced Resin Layer) In order to examine the adhesiveness of the viscoelastic material to the fiber reinforced resin layer, the following sample plate having a viscoelastic material inserted was prepared separately. That is, 16 layers of prepreg sheets: alternating 0 ° and 90 °, laminated positions of viscoelastic material (thickness 0.2 mm): 5-6 layers, 11-12 layers, molding condition: pressure 8 k
A sample plate having a length of 55 mm and a width of 55 mm was prepared under the condition of pressing at a temperature of 150 ° C. for 1 hour in g / square centimeter. The types of viscoelastic materials are the dipole energy film used in the example and the ionomer resin film used in the comparative example. In addition, a sample plate was prepared as a reference in which no viscoelastic material was laminated.

Then, a penetration impact test was conducted on the sample plate. Test equipment: Dynatup, striker Total weight: 1
Each sample plate was tested under the conditions of 2.65 kg, striker diameter: 10 mm, support ring: 40 mm. The test results are shown in Table 1 below. From the results shown in Table 1, as compared with the case of laminating the reference or ionomer resin film without laminating the viscoelastic material, the laminating of the dipole energy film of the example has a large breaking energy,
It can be seen that the adhesiveness is excellent and the impact strength is improved. Further, even if the vibration damping property is seen at the stage of the sample plate, the vibration damping property is high in the laminate of the dipole gee films of the examples.

[0041]

[Table 1]

(Measurement of out-of-plane primary vibration damping rate) FIG. 5 (a)
The upper end of the racket frame 1 was suspended by a string 51 as shown in FIG. 3, and the acceleration pickup 53 was fixed perpendicularly to the frame surface at one continuous point between the head portion 2 and the throat portions 3 and 3. In this state, as shown in FIG. 6, the other continuous point between the head portion 2 and the throat portions 3 and 3 is connected to the impact hammer 5
Excited at 5. The input vibration (F) measured by the force pickup meter attached to the impact hammer 55 and the response vibration (α) measured by the acceleration pickup 53 are passed through amplifiers 56A and 56B to a frequency analyzer 57 (dynamic signal analyzer manufactured by Hewlett Packard). HP3562A) and analyzed. The damping ratio (ζ) was obtained from the following formula and used as the out-of-plane primary vibration damping rate.
The measurement was performed on each of the five racket frames 1 in each of the examples and comparative examples, and the average value thereof was obtained.

Ζ = (1/2) × (Δω / ωn) To = T
n / √2

(Measurement of out-of-plane secondary vibration damping rate) FIG. 5 (b)
As shown in FIG. 5, the upper end of the racket frame 1 was suspended by a string 51, and an acceleration pickup 53 was fixed at a continuous point between the throat portion 3 and the shaft portion 4 perpendicularly to the frame surface. In this state, the frame position on the back side of the acceleration pickup 53 was vibrated by the impact hammer 55. And out of plane 1
The damping ratio was calculated by the same method as the secondary vibration damping ratio, and was taken as the out-of-plane secondary vibration damping ratio. The measurement was performed on each of the five racket frames 1 in each of the examples and comparative examples, and the average value thereof was determined. The measurement results of the above Examples and Comparative Examples are shown in Tables 2 to 4 below.

[0045]

[Table 2]

[0046]

[Table 3]

[0047]

[Table 4]

Comparing the vibration damping ratios of Examples 1 to 19 and Comparative Examples 1, 2, and 5, the Example is sufficiently superior,
In the case of the present invention, the loss factor (tan δ) is 1.0 or more and 0.1 m under the conditions of a frequency of 10 Hz and a temperature of 6 ° C.
It can be seen that the vibration damping property is sufficiently enhanced because the viscoelastic material having a thickness of m or more and 0.6 mm or less is interposed as the vibration absorber. Comparing the vibration damping rates of Example 4 in which the thickness of the viscoelastic material is 0.6 mm and Comparative Examples 3 and 4 in which the thickness of the viscoelastic material is more than 1.0 mm, there is almost no difference between the two, and there is an excessive volume. Vibration damping is sufficiently enhanced with viscoelastic material in the thickness range that can avoid inclusion,
It can be seen that in the racket frame 1 of the present invention, an increase in weight and a decrease in strength are suppressed by avoiding an excessive volume of viscoelastic material.

Comparing the vibration damping ratios of the second and fifth embodiments or the vibration damping ratios of the third and sixth embodiments, in the case where the same amount of viscoelastic material is interposed, the vibration damping ratios of the viscoelastic materials are smaller than those of a single insertion. It can be seen that it is more effective to improve the vibration damping property by dispersively inserting the viscoelastic material. Comparing the vibration damping rates of Examples 6, 9 to 11 and Examples 12 and 13, the viscoelastic material was compared to the third example.
Insertion at the position (left and right throat part) and the first position (range of the head part from 11:00 to 1:00) or the second position (head part from 3:00 to 5:00 (7:00 to 9:00)) causes vibration. It can be seen that it is effective in improving the damping property. Furthermore, Examples 14-1
Comparing the vibration damping ratios of Example 6 and Examples 6 and 9 to 11, the viscoelastic material was used at the third position (left and right throat portions) and the first position (range of the head portion from 11:00 to 1:00) or the second position ( It can be seen that inserting the head portion at two positions from 3 o'clock to 5 o'clock (7 o'clock to 9 o'clock) is very effective in improving the vibration damping property. Further, comparing the vibration damping ratios of Example 18 and Examples 17 and 19, it can be seen that inserting a viscoelastic material in the center of the wall thickness of the fiber reinforced resin layer 10 is effective in improving the vibration damping property. .

[0050]

As is apparent from the above description, according to the racket frame of the present invention, the viscoelastic material as a vibration absorber interposed in the fiber reinforced resin layer has a frequency of 10 Hz,
Since the loss factor (tan δ) is 1.0 or more and the thickness is 0.1 mm or more under the condition of the temperature of 6 ° C., the vibration absorbing property is sufficiently enhanced. Therefore, the vibration transmitted to the human body is suppressed, and the player does not feel uncomfortable,
The occurrence of tennis elbow is also suppressed. In addition, since the thickness of the viscoelastic material is not as thick as 0.6 mm or less, it is possible to avoid the presence of an excessive volume between the layers of the fiber reinforced resin layer, and as a result, it is not necessary to increase the weight so that the racket becomes difficult to swing. At the same time, it is possible to suppress the decrease in strength due to the interposition of the viscoelastic material. Therefore, the racket is easy to swing and durable. That is, the vibration damping property can be improved in a sufficient and appropriate manner.

When the viscoelastic material is inserted between the layers of the fiber reinforced resin layer, it becomes difficult for the viscoelastic material to separate. Furthermore, a thin viscoelastic material may be laminated in a dispersed state, or may be interposed near the center of the thickness of the fiber reinforced resin layer, or at the first position (range from 11:00 to 1:00 of the head portion) and If it is arranged at one or more positions from the second position (3 to 5 o'clock (7 to 9 o'clock) of the head part) and the third position (left and right throat parts), the vibration damping property is further improved. be able to.

[Brief description of drawings]

FIG. 1 is a plan view showing a racket frame of a first embodiment.

FIG. 2 is a plan view showing an intervening position of a viscoelastic material in the first embodiment.

FIG. 3 is a cross-sectional view showing an intervening state of a viscoelastic material in the first embodiment.

FIG. 4 is a schematic view showing a laminated state of the viscoelastic material in the first embodiment.

5 (a) and 5 (b) are schematic diagrams showing a measurement situation of a vibration damping rate.

FIG. 6 is a block diagram showing a vibration damping rate measuring system.

[Explanation of symbols]

1 racket frame 2 head 3 throat section 9 Viscoelastic material (vibration absorber) 10 Fiber reinforced resin layer 10-1 to 10-8 Fiber reinforced prepreg 11 First position 12 Second position 13th position

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jumio Kumamoto 3-6-9 Wakihama-cho, Chuo-ku, Kobe-shi, Hyogo Sumitomo Rubber Industries, Ltd. (56) Reference JP-A-6-155464 (JP, A) JP-A-10-337812 (JP, A) JP-A-8-3326 (JP, A) Actually developed 62-24856 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) A63B 49/10 A63B 49/04

Claims (8)

(57) [Claims] 1. A racket frame made of a molded body in which a plurality of fiber reinforced resin layers made of fiber reinforced prepreg are laminated , wherein a frequency of 10 Hz and a temperature of 6 ° C. are provided in at least a part of the layers of the fiber reinforced resin layers. The loss factor (tan δ) is 1.0 or more and 3.0 or less , and the heating temperature is 10 ° C./min.
The softening point in the SC test was 80 ° C. or higher, and the softening point was 0.
Insert a viscoelastic material with a thickness of 1 mm or more and 0.6 mm or less
The racket frame is characterized by being interposed as a vibration absorber. 2. A matrix resin in the fiber reinforced resin layer.
Is an epoxy resin, and the viscoelastic material is a chlorinated polyethylene.
The racket frame according to claim 1, which is Ren . 3. The at least two viscoelastic materials intervene in a laminated state with the fiber reinforced prepreg sandwiched therebetween, and each viscoelastic material has a thickness of 0.1 mm or more and 0.4 mm or less. The racket frame according to claim 2. 4. The total thickness of the fiber reinforced resin layer is 100%.
As one side and the other side in the thickness direction from the thickness center respectively 2
The racket frame according to any one of claims 1 to 3, wherein at least one viscoelastic material is interposed in a thickness range of 0% or less. 5. A head portion forming a contour of a ball striking face and two throat parts extending from the head portion and confluent with each other at one end are provided, and the top position is 12 o'clock when the ball striking face is viewed as a clock face. Then, one position selected from the first position in the range of 11:00 to 1:00, the second position in the range of 3:00 to 5:00 (7:00 to 9:00), and the third position of the left and right throat parts is selected. The racket frame according to any one of claims 1 to 4, wherein an elastic material is arranged. 6. A head part forming a contour of a ball striking face and two throat parts extending from the head part and confluent with each other at one end are provided, and the top position is 12 o'clock when the ball striking face is regarded as a clock face. Then, at two or more locations selected from the first position in the range from 11:00 to 1:00, the second position in the range from 3:00 to 5:00 (7:00 to 9:00), and the third position in the left and right throat parts. Any one of claims 1 to 4 in which a viscoelastic material is arranged.
Racket frame described in paragraph. 7. The racket frame according to claim 1, wherein the racket frame without strings has a weight of 250 g or less and a balance of 380 mm or less. 8. The weight of the viscoelastic material is in the range of 0.5% or more and 3.0% or less of the weight (low frame weight) of the racket frame in a state where no paint is applied and no strings or parts are used. The racket frame according to any one of paragraphs 7.