JP4737360B2 - Racket frame - Google Patents

Description

  The present invention relates to a racket frame for sports such as tennis, badminton, squash, and more specifically, to improve the vibration absorption by improving a paint applied to a racket frame made of fiber reinforced resin.

In recent years, so-called “thick rakes” have been provided that have a thickness in the out-of-plane direction of the ball striking surface of the racket frame, and users who require the thickness rake require flying performance with less force such as women and seniors. A racket that is lightweight and has good flying performance is required.
Therefore, the mainstream is a racket frame formed of fiber reinforced resin having high strength and high design freedom.

  However, when the tennis racket is reduced in weight, the impact applied to the tennis racket by the tennis ball at the time of hitting is increased, and unpleasant vibration is felt, and the impact is easily transmitted to the elbow, causing a tennis elbow. For this reason, a racket that is lightweight and has high vibration absorption is desired.

  Recently, a lightweight racket of 280 g or less is also provided, and a lightweight racket of 250 g or less is also designed. In a lightweight racket frame made of a prepreg laminate in which reinforced resin is lined up and impregnated with resin, it has been found that the durability can be greatly changed by changing the resin amount of the prepreg by only 4 to 5 g. .

  In light weight rackets, a dynamic damper is attached to the racket frame in order to achieve both weight reduction and vibration damping / shock absorption in consideration of strength, etc., and dynamic vibration absorption is applied to the vibration of the racket frame when hit. Technology has been developed to suppress vibration by synchronizing devices.

For example, in Japanese Examined Patent Publication No. 52-13455 (Patent Document 1), a cantilever type damper made of an elongated elastic member in which a base end of a steel wire having a weight attached to a tip is embedded in a grip end of a racket frame is embedded in the frame. It is proposed to install.
Japanese Patent Laid-Open No. 52-156031 (Patent Document 2) proposes that a base is fixed to a throat portion, the main body is connected to the base through the neck, and the main body is vibrated.
Further, in Japanese Patent Laid-Open No. 62-192182 (Patent Document 3), a racket frame in which a vibration absorber formed by supporting a rod having a mass body mounted on a free end portion thereof by a viscoelastic member is provided on the frame body. Vibration absorbers have been proposed.
However, since all of the above Patent Documents 1, 2, and 3 have a structure in which a dynamic vibration absorber is attached to the frame body, there is a problem that the weight is increased and it is easily disturbed during a swing.

In order to attenuate the vibration at the time of striking instead of the dynamic vibration absorber or together with the dynamic vibration absorber, the present applicant, in Japanese Patent Application Laid-Open No. 2001-204852 (Patent Document 4), And / or a racket frame using a vibration-damping paint as at least a part of the appearance paint.
However, the vibration-damping paint used as a putty or external fitting paint in Patent Document 4 has a low tensile elastic modulus and tensile elongation at break, and thus cannot follow the large deformation of the low frame, and the putty composed of the low frame surface and the vibration-damping paint. There was a problem that peeling or cracking occurred at the boundary.
Japanese Patent Publication No.52-13455 Japanese Patent Laid-Open No. 52-156031 JP-A-62-192182 JP 2001-204852 A

  The present invention has been made in view of the above problems, and a damping paint applied to the surface of a low frame in order to improve vibration damping while maintaining the lightness of the racket frame is used to deform the low frame at the time of impact. An object is to prevent the occurrence of peeling and cracking of the vibration-damping paint so that it can follow.

In order to solve the above problems, the present invention is a racket frame including a frame body and a yoke including a head portion, a throat portion, a shaft portion, and a grip portion,
On the surface of the low frame of the frame body molded from fiber reinforced resin, a base paint putty and a base paint layer applied to the surface of the putty, a clear paint layer applied to the surface of the base paint layer, a clear paint layer comprising a coating of a multi-layer consisting of a top coating paint layer applied to the surface, as a coating material of the innermost side of the base paint layer using a damping coating of the coating film, 該制vibration paint urethane The main component made of resin and the curing agent are diluted with a diluent, and the total amount of the main component and the curing agent is 100% by weight, and the silver powder is 5% by weight or more and the coloring pigment is 5% by weight or more. ,
The coating film made of the vibration-damping coating material has a tensile modulus measured according to JIS K 5400 of 0.5 MPa or more and 10.0 MPa or less and a tensile elongation at break of 40% or more and 150% or less , and
There is provided a racket frame in which the base paint layer of the yoke is formed from the vibration-damping paint, and the yoke is formed of a viscoelastic material having a flexural modulus of 100 MPa to 1500 MPa .

  Conventionally, on the surface of the low frame (the racket frame before the surface paint is applied), putty is applied as the base paint to smooth the surface of the low frame, and several appearance paints are applied to the surface of the putty layer, and the inner circumference A base paint layer, a clear paint layer, and a top coating paint layer are provided from the side. It is necessary to use a relatively hard paint for the top coating paint layer and the clear paint layer on the outer peripheral side during the manufacturing process so as not to be damaged by contact with an external interference material when using the racket. On the other hand, since the putty needs to be ground to form a smooth surface, the coating thickness at each part is not uniform and the coating thickness needs to be relatively large. When the thickness is increased, the adhesion and strength with the low frame are lowered, and there is a problem in using a vibration-damping coating material having a relatively low strength for the entire putty. A pigment or silver powder is added to the base paint layer in contact with the putty for coloring. When silver powder is added to the paint, the paint becomes hard and the tensile elongation at break is reduced to about half.

Therefore, in the present invention, the outer periphery of the putty is located on the innermost peripheral side in contact with the putty among the plurality of outer appearance coating layers, is hardened by the silver powder, and the base paint layer has a reduced tensile elongation at break. Damping paint is used. As described above, the coating film made of the vibration-damping paint has a tensile elastic modulus of 0.5 MPa to 10.0 MPa and a tensile elongation at break of 40% to 150%. Even in the added state, the vibration damping property of the racket can be enhanced by setting it to low elasticity and high tensile elongation at break. In particular, by providing a base paint layer made of vibration-damping paint between the relatively hard clear paint layer, top coating paint layer and racket frame, vibration transmitted to the top coating paint layer in contact with the player's hand on the racket surface is transmitted. Can be suppressed. As a result, the player is less uncomfortable and the occurrence of tennis elbows can be suppressed. In addition, since only a vibration-damping paint having a high vibration damping rate is used in place of the conventionally used appearance paint, there is almost no increase in weight, and the demand for weight reduction can be met.

  In addition, since the vibration-damping paint having a large tensile break elongation is used for the base paint layer, it is possible to follow the deformation of the racket frame at the time of hitting and prevent the occurrence of cracks.

The tensile elastic modulus of the coating film made of the vibration-damping paint used for the base paint layer is 0.5 MPa or more and 10.0 MPa or less, preferably 1.0 MPa or more and 9.0 MPa or less, more preferably 1.5 MPa or more and 3.5 MPa or less. Yes.
This is because it is possible to easily follow the frame vibration by setting the tensile elastic modulus of the coating film made of the vibration-damping coating to 0.5 MPa or more, while vibration damping cannot be sufficiently improved when it exceeds 10.0 MPa. .

Further, the tensile elongation at break of the coating film made of the vibration-damping paint is set to 40% or more and 150% or less. This is because if the tensile elongation at break is less than 40%, it will not be possible to follow the deformation of the racket frame at the time of hitting and a crack will occur. The upper limit of tensile elongation at break is not limited as the essence of the invention, but is 150% from available materials.

The base paint layer and the vibration damping paints, pigments for coloring are always formulated, hardness alone on SL silver powder is 5 wt% blend becomes large, since the elongation at break elongation is halved, In particular, the vibration-damping coating material having a large tensile elastic modulus and tensile elongation at break is preferably used .

As the damping coatings, rubber, resin, there are asphalt-based, in the resin system, lees blue as the base resin, epoxy-based, vinyl-based, but a urethane-based or alkyd resin, in the present invention The main ingredient is urethane resin. Strength of the coating, the control of the viscoelastic behavior, hue as the pigment, et al are added for the purpose of adding such flaky in terms of the absorption of vibration energy, acicular, pigment fibrous is used, graphite, mica, synthetic fibers Powder or the like is used. In the state where these pigments and silver powder are mixed, a vibration-damping coating material having a tensile modulus and a tensile elongation at break within the above ranges is used.

As the vibration-damping paint, an aqueous acrylic / emulsion paint that does not use an organic solvent is preferable because it is environmentally friendly and does not adversely affect the fiber reinforced resin that constitutes the frame. As this type of anti-vibration coating, for example, the coating film component is made of a polar polymer selected from polyvinyl chloride, chlorinated polyethylene, acrylic rubber, and acrylonitrile-butadiene rubber. Examples include Urenaine DP201 and DP401 manufactured by CCI, which contain an active ingredient composed of a compound containing a mercaptobenzothiazyl group to be increased . In addition, PU3700 and PU3720 manufactured by Deokken of Taiwan nationality and PU65200 manufactured by Euryaku are also included.

It is preferable that the thickness of the base paint layer made of the vibration-damping paint is 0.1 mm to 3.0 mm, and the weight of the vibration-damping paint applied to the racket frame is 2 g to 36 g.
The reason why the thickness is in the above range is that if the thickness is less than 0.1 mm, the vibration damping property is lowered, and if the thickness is larger than 3.0 mm, the weight is increased and the operability is lowered. Also, the weight is in the above range because if it is less than 2 g, vibration damping cannot be improved sufficiently, and conversely, if it exceeds 36 g, the weight of the racket frame becomes too heavy and the operability deteriorates. is there. In addition, when the weight of the racket is defined in design, if it is heavier than 36 g, the racket frame itself must be reduced in weight, and the strength design becomes difficult.

The above-mentioned vibration-damping paint is most effective when applied to the entire racket frame, but it may not be applied to the entire racket frame, but may be partially applied to a portion with a large amplitude in consideration of the vibration mode at the time of impact. . Specifically, the vibration-damping paint is applied to the racket frame total length L at a position from 0.3 L to 0.7 L from the grip end.
This is because the antinode of the out-of-plane primary vibration mode (where the amplitude is large) is in the range of 0.3 L to 0.7 L from the grip end, and the out-of-plane secondary vibration mode is from 0.1 L to the grip end. It exists in the range of 0.4L and the range of 0.6L to 0.9L from the grip end. Therefore, in order to effectively attenuate out-of-plane primary and out-of-plane secondary vibrations, the range of 0.3 L to 0.7 L from the grip end is preferable. Among them, it is particularly preferable to apply the damping paint to the base paint layer of the yoke located in the range of 0.3 L to 0.7 L from the grip end with respect to the total length L.

Further, the yoke whose base paint layer is made of a vibration-damping paint is formed of a viscoelastic material having a flexural modulus of 100 MPa or more and 1500 MPa or less, and both ends in the length direction thereof are ruggedly fitted to the frame body to provide vibration damping properties. When fixed through the adhesive, the vibration generated at the time of striking can be absorbed by the boundary between the yoke and the frame body, the material of the yoke body, and the base paint layer of the yoke, and vibration damping can be improved.
Needless to say, a viscoelastic material having a flexural modulus of 100 MPa or more and 1500 MPa or less may be attached to the frame body at another location.

  The reason why the viscoelastic material is in the above range is that it is too soft when the flexural modulus is less than 100 MPa. This is because they do not fit. On the other hand, when it exceeds 1500 MPa, it becomes too hard, and even out-of-plane secondary vibration with a relatively large natural frequency is not matched with out-of-plane primary vibration with a small natural frequency.

The damping paint may be used for at least a part of the putty. In particular, it is preferable to use the part of the base paint layer where the base paint layer is formed of the damping paint as the damping paint for the base paint layer.
With the above configuration, since the soft damping paint is also used for the putty located on the inner surface side of the base paint layer, deviation occurs between the putty and the base paint layer, and vibration damping can be further improved. .

  The vibration-damping paint is suitably used for a racket frame having a racket frame length of 660 mm or more and 730 mm or less and a racket weight of 100 g or more and 280 g or less when no string is stretched. The reason is that if the total length is less than 660 mm, when hitting a distant ball at the time of play, the ball is hit off-center at the top part, and the flying performance is reduced and the total length is short. This is because the moment of inertia decreases and the flying performance decreases. On the other hand, if the total length is 730 mm or more, the operability is deteriorated. Further, when the weight is less than 100 g, the operability is improved, but the strength is decreased, while when it is 280 g or more, the operability is decreased.

  As apparent from the above description, according to the present invention, the tensile modulus of elasticity is applied to the innermost base paint layer of the outer coating film composed of a plurality of layers on the outer peripheral surface of the putty provided on the outer peripheral surface of the low frame. The vibration damping property of the tennis racket can be improved and the base paint layer can follow the deformation of the racket frame due to the use of a vibration-damping paint with low tension and high elongation at break. Can be prevented.

Embodiments of the present invention will be described with reference to the drawings.
FIG.1 and FIG.2 shows 1st Embodiment of the racket frame for tennis of this invention.

  As shown in FIG. 1, the racket frame is formed of a pipe made of a prepreg laminate, and the head portion 12, the throat portion 13, the shaft portion 14, and the grip portion 15 are continuously formed to form the frame body 11. Both ends of the yoke 17 are connected to the throat portions 13 on both sides to form the low frame 10 including the frame body 11 and the yoke 17. The yoke 17 forms a gut stretch portion G surrounding the hitting surface F together with the head portion 12, and the gut stretch portion G is provided with a gut hole (not shown) for string stretching.

As shown in FIG. 2, a putty 20 is applied to the surface of the low frame 10, and three layers of paint, a base paint layer 21, a clear paint layer 22, and a top coating paint layer 23, are applied to the surface of the putty from the inner peripheral side. A layer is provided.
The entire surface of the low frame 10 including the frame body 11 and the yoke 17 is formed with the base paint layer 21 made of the damping paint A, the putty 20 with the epoxy paint B, the clear paint layer 22 with the urethane paint C, and the top coating paint layer. 23 uses a urethane paint D.

In the vibration-damping paint A forming the base paint layer 21, a coloring pigment and silver powder are blended in the resin composition. The damping paint A is a mixture of a main agent, a curing agent and a diluent, and 5% by weight of silver powder is blended in 100% by weight of the main agent and the curing agent.
The tensile elastic modulus of the coating film made of the vibration damping paint A is 0.5 MPa or more and 10.0 MPa or less (in this embodiment, the tensile elastic modulus is 8.9 MPa), and the tensile elongation at break is 40% or more and 150% or less ( In this embodiment, the tensile elongation at break is 40.9%).

The putty 20, the clear paint layer 22, and the top coating paint layer 23 are formed of the same paint as the conventional one. The coating film made of the urethane paint C used for the clear paint layer 22 has a tensile elastic modulus of 0.92 MPa and a tensile breaking elongation of 87.8%. The coating film made of the urethane coating D used for the top coating paint layer 23 has a tensile elastic modulus of 1.34 MPa and a tensile breaking elongation of 73.9%.

With the above configuration, out of the putty 20, the base paint layer 21, the clear paint layer 22, and the top coating paint layer 23 on the outer peripheral surface of the low frame 10, the base paint layer 21 has a low tensile elastic modulus and has a tensile elongation at break. Since the coating film is made of a high vibration-damping paint, the vibration damping property of the tennis racket can be improved, and the base paint layer can follow the deformation of the racket frame 10 and thus the occurrence of cracks can be prevented. .

  3 to 6 show a double yoke racket frame according to the second embodiment of the present invention. The first yoke 18 shown in FIG. 4 is mounted on both lower sides of the head portion 12 ′ of the frame body 11 ′ shown in FIG. The second yoke 19 is attached to the boundary position between the lower head portion 12 'and the throat portion 13'.

  The first yoke 18 is composed of a pair of viscoelastic materials divided so as to be sandwiched between both sides of the gut with a gap, and is in contact with the two vertical guts g with a vibration damping material 30 interposed in a part of the gap. I am letting.

As shown in FIG. 4, the first yoke 18 integrally includes a left and right attachment portion 18 a that is fitted and fixed to the left and right frame portions of the gut stretch portion G ′ and a bridging portion 18 b that connects the left and right attachment portions 18 a. Molding.

  The width in the out-of-plane direction of the bridging portion 18b is reduced toward the center portion, and the striking surface F ′ side is set as a gut insertion groove 18c, and vibration occurs at a substantially central position in the length direction (weft direction) of the gut insertion groove 18c. A convex portion 18d for attaching the damping material 30 is provided. Further, a pin 18e is provided on one end side of the bridging portion 18b so as to project toward the ball striking face F, and a recess 18f for inserting the pin 18e is provided at a position symmetrical to the pin 18e on the other end side.

  The left and right attachment portions 18a of the first yoke 18 are bent according to the shape of the frame of the gut stretch portion G ', and a through hole 18g is provided at the center.

  Further, when the first yoke 18 is attached to the frame body 11, a got insertion hole 18 h is formed so that the got insertion grooves 18 c of the pair of first yokes 18 are opposed to each other.

The length of the bridging portion 18b of the first yoke 18 is 135 mm, the width of the bridging portion 18b in the out-of-plane direction is 14.85 mm, the length of the gut insertion groove 18c is 115.0 mm, and the first yoke 18 and the gut stretched portion G. The total joint area with 'is 28 cm ² . The weight of the first yoke 18 is 10 g.

As shown in FIG. 5A, a vibration damping material 30 is disposed in the gut insertion hole 18 h of the first yoke 18, and the vibration damping material 30 is located at the center in the length direction of the first yoke 18. positioned.
As shown in FIG. 5B, the vibration damping material 30 is provided with V-shaped grooves 31 at both ends, and a recess 32 is formed by providing a notch at the lower end 31 a of the groove 31. In addition, the vibration damping material 30 has a top surface 31b that is gently recessed in an arc shape in accordance with the shape of the first yoke 18, and a bottom surface 31c that is gently inflated in an arc shape. The side surface 31d in the length direction is gently expanded into an arc shape in accordance with the shape of the gut insertion hole 20C, and a groove 31e is provided on the side surface 31d.

The vibration damping material 30 has a length of 21.11 mm, a width of 7.65 mm, a thickness of 4.91 mm, a length of the groove 31e of 11 mm, a width of 3.61 mm, and a groove depth of 1.00 mm. Moreover, the complex elastic modulus E * of the vibration damping material 30 under a measurement condition of a frequency of 10 Hz and a temperature of 0 to 10 ° C. is 1.00 × 10 ⁵ dyn / cm ² or more and 5.00 × 10 ⁸ dyn / cm ^2. Hereinafter, more preferably 1.00 × 10 ⁷ dyn / cm ² or more and 2.00 × 10 ⁹ dyn / cm ² or less, and in this embodiment, the complex elastic modulus E * is 1.41 × 10 ⁷ dyn / cm ^2. It is said.

The first yoke 18 is attached so that the gut stretched portion G 'is sandwiched from both sides in the out-of-plane direction by the left and right attaching portions 18a. Specifically, the convex portion provided on the gut stretch portion G ′ and the through hole 18g provided in the left and right attachment portions 18a of the first yoke 18 are fitted, and the pin 18e of the first yoke 18 is paired. The first yoke 18 is attached to the frame body 11 'by being inserted into the recess 18f of the first yoke 18, respectively. The first yoke 18 and the racket frame 11 'are fixed with a vibration-damping adhesive interposed therebetween.

After the first yoke 18 is attached to the frame body 11 ′ as described above, the convex portion 18d provided at the center position of the first yoke 18 and the concave portion 31e provided in the vibration damping material 30 are fitted, and the first An adhesive is interposed between the yoke 18 and the vibration damping material 30 and bonded, and the vibration damping material 30 is interposed in the gut insertion hole 18 h of the first yoke 18.
In this state, the gut g is stretched on the gut stretch portion G ′, and among the vertical guts g inserted through the gut insertion holes 18 h of the first yoke 18, the two central guts g in the center are connected to the vibration damping material 30. It fits into the recess 32.

The first yoke 18 is disposed within a range of 0.3 L to 0.6 L from the grip end with respect to the frame total length L. In the present embodiment, the position where the first yoke 18 is connected to the left and right frames of the gut stretch portion G ′ is 0.46L. The first yoke 18 is arranged so as to be symmetric with respect to the left and right hitting surface F. In the present embodiment, the length of the gut g stretched in the vertical direction is 340 mm to 420 mm.

The first yoke 18 is formed of a viscoelastic material having a flexural modulus of 100 MPa to 1500 MPa (730 MPa in the present embodiment), putty 20 is applied to the outer peripheral surface thereof, and a vibration damping coating is applied to the surface of the putty 20. Is applied to provide a base paint layer 21, a clear paint layer 22, and a top coating paint layer 23. In the second embodiment, only the base paint layer 21 of the first yoke 18 is formed of a vibration-damping paint A ′ different from the first embodiment. Also, the damping paint A ″ is used for the putty 20. The same paints C and D as in the first embodiment are used for the clear paint layer 22 and the top coating paint layer 23. The first embodiment Similarly to the above, the damping paint A ′ for the base paint layer is blended with a required amount of silver powder.

The coating film made of the vibration-damping paint A ′ used for the base paint layer 21 has a tensile elastic modulus of 1.6 MPa and a tensile elongation at break of 53.2%.

  With the above configuration, the first yoke 18 having a large amplitude at the time of striking is formed of a viscoelastic material, and the damping paint A ″ is also used for the putty, so that the vibration attenuation of the tennis racket can be further improved. In particular, since the string comes into contact with the first yoke 18 by vibration at the time of striking, the string vibration can also be attenuated.

Hereinafter, examples of the racket frame of the present invention and comparative examples will be described in detail.
In both the examples and comparative examples, the frame body is a hollow shape of fiber reinforced resin, the racket frame has a maximum thickness of 28 mm, a width of 13 to 14.5 mm, and a hitting area of 125.11 square inches. Molded.

  On a mandrel (φ14.5mm) with an internal pressure tube made of 66 nylon coated with a prepreg sheet (CF prepreg (Toray T300, T700, T800, M46J)) made of fiber reinforced thermosetting resin using carbon fiber as the racquet frame And a vertical laminate was molded. The prepreg angles were laminated at 0 °, 22 °, 30 °, and 90 °. The mandrel was removed and the vertical laminate was set in a mold. The mold is clamped, and the mold is heated to 150 ° C. and heated for 30 minutes. At the same time, an air pressure of 9 kgf / cm 2 is applied to the internal pressure tube, and the pressure is maintained and created by heat and pressure molding. did.

  The weight (mass excluding string) and balance were set as shown in Table 1 below.

Example 1
A first yoke and a second yoke made of the same material as the frame main body were integrally formed on the frame main body. For the base paint layer, PU3270 manufactured by Tokuken Co., Ltd., which is a vibration-damping paint, was used as a main agent. The weight ratio of main agent: curing agent: diluent is 3: 1: 6, 5% by weight of silver powder (Tsubaki specially made PTT001) and appropriate amount of brightener (clear) in 100% by weight of main agent and hardener. Was blended and applied by spraying. N-3375 manufactured by Bayer was used as a curing agent, and BAC manufactured by Changchun Petrochemical was used as a diluent. When PU3270 (including a curing agent and a diluent) was added with silver powder, the tensile modulus was 8.9 MPa, and the tensile elongation at break was 40.9%. The tensile elastic modulus and tensile elongation at break were measured according to JIS K 5400. The vibration-damping paint was used for the entire base paint layer of the racket.
As a putty, an epoxy paint MPEL-128 made by Nanya was used as a main agent, and the weight ratio of main agent: curing agent was set to 100: 1. As a curing agent, N-3375 manufactured by Bayer was used.
For the clear paint layer, PU3700 manufactured by Tokuken Co., Ltd., which is a urethane-based paint, was used as a main agent. The weight ratio of the main agent: curing agent: diluent was 6: 1: 4. The curing agent and diluent used were the same as those for the base paint layer.
For the top coating paint layer, PU3720 manufactured by Tokuken Co., Ltd., which is a urethane-based paint, was used as a main agent. The weight ratio of main agent: curing agent: diluent was 4: 1: 2. The curing agent and diluent used were the same as those for the base paint layer.

(Example 2)
For the base paint layer, PU3700 made by Tokuken Co., Ltd., which is a vibration-damping paint, was used as a main agent. The weight ratio of the main agent: curing agent: diluent was 6: 1: 4, 5% by weight of the above-mentioned silver powder and an appropriate amount of brightener were blended in 100% by weight of the main agent and the curing agent, and applied by spraying. . The same curing agent and diluent as in Example 1 were used. The tensile elastic modulus of PU3700 (including a curing agent and a diluent) added with silver powder was 3.3 MPa, and the tensile elongation at break was 46.1%. The tensile elastic modulus and tensile elongation at break were measured according to JIS K 5400. The vibration-damping paint was used for the entire base paint layer of the racket. Others were the same as in Example 1.

(Example 3)
For the base paint layer, PU65200 manufactured by Eurisha Co., Ltd., which is a vibration-damping paint, was used as a main agent. The weight ratio of the main agent: curing agent: diluent was 9: 1: 3, 5% by weight of the above-mentioned silver powder and an appropriate amount of brightener were blended in 100% by weight of the main agent and the curing agent, and applied by spraying. . The same curing agent and diluent as in Example 1 were used. The tensile elastic modulus of PU65200 (including a curing agent and a diluent) added with silver powder was 1.6 MPa, and the tensile elongation at break was 53.2%. The tensile elastic modulus and tensile elongation at break were measured according to JIS K 5400. The vibration-damping paint was used for the entire base paint layer of the racket. Others were the same as in Example 1.

Example 4
DP201 made by CCI, which is a vibration-damping paint, was used for the putty. The vibration-damping paint was used for the entire racket putty. Others were the same as in Example 3.

(Example 5)
The first yoke was formed of PEBAX 7233 (a flexural modulus of 730 MPa, measured according to ASTM D 790), which is a viscoelastic material, and adhered to the frame body. Others were the same as in Example 3.

(Example 6)
As in the second embodiment, the first yoke was formed of PEBAX 7233, which is a viscoelastic material, adhered to the frame body, and DP201 made by CCI was used for the putty. Others were the same as in Example 3.

(Comparative Example 1)
For the base paint layer, PU217 manufactured by Kodaisha was used as the main agent. The weight ratio of the main agent: curing agent: diluent is 3: 1: 1, and 5% by weight of the above-mentioned silver powder and an appropriate amount of brightener are blended in 100% by weight of the main agent and the curing agent, and sprayed. It applied by. The same curing agent and diluent as in Example 1 were used. The tensile modulus of the material obtained by adding silver powder to PU217 (including a curing agent and a diluent) was 17.6 MPa, and the tensile elongation at break was 11.9%. The tensile elastic modulus and tensile elongation at break were measured according to JIS K 5400. Others were the same as in Example 1.

(Comparative Example 2)
The first yoke was formed of PEBAX 7233, which is a viscoelastic material, and adhered to the frame body. Others were the same as in Comparative Example 1.

(Comparative Example 3)
DP201 made by CCI was used for the putty, base paint layer, clear paint layer and top coating paint layer.
DP201 of the base paint layer was mixed with 5% by weight of the above-mentioned silver powder and an appropriate amount of brightener in 100% by weight. Others were the same as in Comparative Example 1.

  About the tennis racket of the said Example and the comparative example, the out-of-plane primary vibration attenuation rate and the out-of-plane secondary vibration attenuation rate were measured by the method mentioned later, and the actual hit test, the crack test, and the scratch test were done.

(Measurement of out-of-plane primary vibration damping rate)
7A, the upper end of the head portion 12 is suspended by a string 51, and an acceleration pickup meter 53 is attached to one continuous point of the head portion 12 and the throat portion 13 as shown in FIG. Fixed vertically. In this state, as shown in FIG. 7B, the other continuous point of the head portion 12 and the throat portion 13 was vibrated with an impact hammer 55. An input vibration (F) measured by a force pickup meter attached to the impact hammer 55 and a response vibration (α) measured by an acceleration pick-up meter 53 are subjected to a frequency analysis device 57 (manufactured by Hewlett-Packard Company, dynamics) through amplifiers 56A and 56B. Single analyzer HP3562A) was input and analyzed. The transfer function in the frequency domain obtained by the analysis was obtained, and the frequency of the tennis racket was obtained. The vibration damping ratio (ζ) was obtained from the following equation, and used as the out-of-plane primary vibration damping rate. The average value measured about the racket of the Example and the comparative example is shown in Table 1 above.

ζ = (1/2) × (Δω / ωn)
To = Tn / √2

(Measurement of out-of-plane secondary vibration attenuation rate)
As shown in FIG. 7C, the upper end of the head portion 12 is suspended by a string 51, and the acceleration pickup meter 53 is fixed perpendicularly to the frame surface at a continuous point between the throat portion 13 and the shaft portion. In this state, the frame on the back side of the acceleration pickup meter 53 was vibrated with an impact hammer 55. Then, the attenuation rate was calculated by a method equivalent to the out-of-plane primary vibration attenuation rate, and the out-of-plane secondary vibration attenuation rate was obtained. The average value measured about the racket of the Example and the comparative example is shown in Table 1 above.

(Actual test)
A questionnaire survey was conducted on the vibration absorption of the racket. We scored with a maximum score of 5 (the better the better), and the average score of 63 middle / advanced players (women who fulfilled the requirement to play tennis for more than 10 years and still play for more than 3 days a week).

(Crack test)
100 tennis balls were hit at a speed of 50 m / sec at a position 6 cm from the top position of the head of the racket. Table 1 shows the case where no crack was generated at this time, and the case where a crack was generated was evaluated as x.

(Scratch test)
The frame surface of the racket was rubbed with 6.6-nylon. At this time, the paint on the surface of the frame that was not worn or peeled off was evaluated as 、, and the generated paint was evaluated as × and is shown in Table 1 above.

As shown in Table 1, from Comparative Example 1 and Examples 1, 2, and 3, it was confirmed that the vibration damping property of the tennis racket was improved as the tensile elastic modulus of the coating film of the base paint layer was decreased.
Further, from Example 4, it was confirmed that when DP201 having a good vibration damping property was used for the inner peripheral side putty of the base paint layer, the vibration damping property was improved. It is thought that because the putty is soft, displacement between layers occurs and vibration damping is improved.
Furthermore, it was confirmed from Examples 5 and 6 that when the first yoke was molded with PEBAX 7233, which is a viscoelastic material, the vibration damping performance was dramatically improved.

Due to the great coating of tensile elongation at break to the base paint layer in Example 5, there was no occurrence of cracking following the deformation of the first yoke which is formed by the viscoelastic material, in Comparative Example 2, the base due to the small coating of tensile elongation at break in a paint layer, a crack can not follow the deformation of the first yoke molded occurs by the viscoelastic material.
In addition, if DP201 with good vibration damping is used for the putty, base paint layer, clear paint layer, and top coating paint layer, the vibration damping of the tennis racket is improved, but the surface becomes brittle, and wear occurs in the scratch test. did.

It is the schematic which shows the racket frame of 1st Embodiment of this invention. It is principal part sectional drawing of 1st Embodiment. It is the schematic which shows the racket frame of 2nd Embodiment of this invention. The 1st yoke is shown, (A) is a front view, (B) is a top view. (A) is a drawing showing a state where a vibration damping material is attached to a first yoke, (B) is a perspective view of the vibration damping material, and (C) is a plan view of the vibration damping material. It is principal part sectional drawing of 2nd Embodiment. (A)-(C) are drawings which show the measuring method of a vibration damping factor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Low frame 11 Frame main body 12 Head part 13 Throat part 14 Shaft part 15 Grip part 17 Yoke 18 1st yoke 19 2nd yoke 20 Putty 21 Base paint layer 22 Clear paint layer 23 Top coating paint layer 30 Vibration damping material A Damping Paint B Epoxy paint C, D Urethane paint

Claims (3)

A racket frame comprising a frame body and a yoke comprising a head part, a throat part, a shaft part and a grip part,
On the surface of the low frame of the frame body molded from fiber reinforced resin, a base paint putty and a base paint layer applied to the surface of the putty, a clear paint layer applied to the surface of the base paint layer, a clear paint layer comprising a coating of a multi-layer consisting of a top coating paint layer applied to the surface, as a coating material of the innermost side of the base paint layer using a damping coating of the coating film, 該制vibration paint urethane The main component made of resin and the curing agent are diluted with a diluent, and the total amount of the main component and the curing agent is 100% by weight, and the silver powder is 5% by weight or more and the coloring pigment is 5% by weight or more. ,
The coating film made of the vibration-damping coating material has a tensile modulus measured according to JIS K 5400 of 0.5 MPa or more and 10.0 MPa or less and a tensile elongation at break of 40% or more and 150% or less , and
A racket frame in which a base paint layer of the yoke is formed of the vibration-damping paint, and the yoke is formed of a viscoelastic material having a bending elastic modulus of 100 MPa to 1500 MPa . The thickness of the damping paint for the base paint layer is 0.1 mm to 3.0 mm ,
該制vibration paint of the frame body entirely or racket frame according to 請 Motomeko 1 are applied from the handle end to 0.7L frame body of the following positions or 0.3L relative racket frame total length L,. The racket frame according to claim 1 or 2, wherein at least a part of the putty is formed of the vibration-damping paint .

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