JPH10201882A - Racket frame and manufacturing method thereof - Google Patents

Abstract

(57) [Problem] To provide a racket frame that is lightweight, has high stability of a hitting surface, and has a moderate vibration damping property. SOLUTION: This is a hollow racket frame made of fiber reinforced resin, which is reinforced by using a thermosetting resin such as an epoxy resin and a thermoplastic resin such as RIM nylon having a same molding temperature as a matrix resin. The layer made of the above-mentioned thermosetting resin is used as the inner layer, and the layer made of the above-mentioned thermoplastic resin reinforced is used as the outer layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a racket frame for tennis or the like, and more particularly, to a hollow racket frame made of fiber reinforced resin, which has excellent strength and stability of a hitting surface despite being lightweight. The present invention also relates to a racket frame having good vibration damping properties.

[0002]

2. Description of the Related Art In recent years, hollow racket frames made of fiber-strength resin have become mainstream as racket frames because of their light weight, high rigidity, high strength, and excellent durability. This type of racket frame is usually integrally molded from a thermosetting resin reinforced with high-strength, high-modulus fibers such as carbon fibers. However, the racket frame using the high-strength, high-elastic modulus reinforcing fibers and thermosetting resin as a matrix resin is excellent in rigidity and strength, but is likely to generate vibration when subjected to an impact, so There is a problem that tennis elbows and the like easily occur.

[0003] In order to improve the vibration damping property while using a thermosetting resin as the matrix resin, there is an example in which organic fibers such as aramid fiber and ultrahigh molecular weight polyester fiber are used. Since organic fibers have low rigidity and strength, it is impossible to use only these organic fibers as reinforcing fibers. Therefore, it is inevitable to use carbon fiber or the like in combination, and as a result, the vibration damping rate becomes as low as 0.6% or less,
The vibration damping rate has not been increased.

Therefore, recently, in order to increase the vibration damping rate,
A racket frame using a continuous fiber as a reinforcing fiber and a thermoplastic resin such as a polyamide resin as a matrix resin has been provided. Specifically, first, a racket frame obtained by injection-molding a polyamide resin containing short fibers, and second, fibers of a material serving as a matrix resin and reinforcing fibers are laminated on the outer periphery of the tube in a fiber form and placed in a mold. Then, under high temperature, a pressure was applied to the tube, the matrix resin was melted and molded, and a racket frame was formed. Third, reinforcing fibers were previously arranged in a mold, and a polyamide resin monomer was injected to perform reaction injection molding. A racket frame is provided.

The vibration damping rate of the first racket frame is 1.9%, that of the second racket frame is 0.92%,
In the third racket frame, it is 1.1%. In this way, the racket frame using thermoplastic resin as the matrix resin reflects the high toughness of the thermoplastic resin, and the shock resistance and vibration that were not obtained with the conventional thermosetting resin racket frame. Has damping properties.

However, in general, thermoplastic resins have a higher environmental dependency of the elastic modulus than thermosetting resins, and there is a problem that characteristics such as rigidity are easily changed depending on the use environment of the racket frame. In particular, for athletes, the stability of the striking surface is required, and so-called in-plane rigidity is an important performance, and it is not preferable that the in-plane rigidity is low or changes. Further, if the vibration damping rate is too large, the response of the shot feeling becomes dull, and the response when the player deviates from the sweet area is slow, resulting in inferior competitiveness.

[0007]

As described above, it is a problem whether the vibration damping property and the rigidity are too large or too small. As a result of an experiment conducted by the inventor, specifically, the vibration damping property shows that the damping rate of the primary natural frequency in the out-of-plane direction in the equilibrium state at a temperature of 25 ° C. and a humidity of 60% is 0.6% to 0.9%.
%, The rigidity in the in-plane direction is in the range of 100 to 150 kgf / cm ² , a tennis elbow or the like is not generated, the response of the shot feeling does not become dull, and the stability of the hitting surface is good. Turned out to be a range. However, at present, no commercially available tennis racket frame having a vibration damping rate in the above range and rigidity in the in-plane direction has been provided.

Furthermore, recently, in many cases, spins are applied at the time of play or a writhing method is used, and in order to cope with this play style, operability of the racket is regarded as important, and in that respect, weight reduction is achieved. There is a strong demand.

A racket frame using both a thermosetting resin and a thermoplastic resin as a matrix resin has been proposed in Japanese Patent Application Laid-Open Nos. 1-121074 and 7-47152, all of which have the following problems. Had a point.

First, the conventional example of Japanese Patent Laid-Open No. 1-12077 is disclosed.
No. 4 proposes a racket frame characterized by mixing a fiber-reinforced thermosetting resin and a fiber-reinforced thermoplastic resin. Specifically, on the outer periphery of the core material, a prepreg in which a thermosetting resin is impregnated into reinforcing fibers, and a fiber-reinforced thermoplastic resin sheet, are formed by coating any one as an inner layer and the other as an outer layer. ing. In this conventional example,
The molding temperature of the thermosetting resin and the thermoplastic resin used is not described at all and is unknown. Generally, the curing temperature of a thermosetting resin is from room temperature to 180 ° C., and the melting temperature of a thermoplastic resin is as high as 220 ° C. to 260 ° C. In this conventional example, it is described that the interfacial adhesiveness between the thermoplastic resin and the thermosetting resin, when the thermosetting resin is cured, the thermoplastic resin is melted or softened, so that the adhesion becomes higher. ,
It may not be softened, and there is a problem in terms of adhesion. Also,
Conversely, when the melting point or softening point of the thermoplastic resin is lower than the curing temperature of the thermosetting resin, the racket frame has poor heat resistance. As described above, in the conventional example, since the types and the molding temperatures of the thermosetting resin and the thermoplastic resin are not specified, simply coating and laminating these sheets and heating the racket frame includes various problems. Which is not feasible.

Further, Japanese Patent Application Laid-Open No.
Japanese Patent Application Laid-Open No. H11-157, proposes a racket frame including a region in which a mixture of the thermoplastic resin and the thermosetting resin is provided between the fiber-reinforced thermosetting resin and the fiber-reinforced thermoplastic resin. Specifically, after molding the frame part of the racket frame with a fiber-reinforced thermoplastic resin, molding the grip part with a fiber-reinforced thermosetting resin, and then using an adhesive in which the thermosetting resin and the thermoplastic resin are mixed. A method of joining is disclosed.
However, when the frame portion and the grip portion are separately formed and joined with an adhesive, stress concentration occurs in the joined portion, which causes a problem in strength and is not suitable for practical use. Further, the outer periphery of the core material was coated with a fiber-reinforced thermoplastic resin sheet, and the outer surface thereof was coated with a porous thermoplastic resin sheet in the same manner as in the conventional example. Thus, there is disclosed a case of molding in a mold by pressurizing and heating, but similarly to the conventional example, the molding temperature of the thermoplastic resin and the thermosetting resin becomes a problem, and the bonding at the interface is problematic. There is a problem with the properties, which is also unsuitable for practical use.

The present invention has been made in view of the above-mentioned problems of the prior art, and has a practical application in which a thermosetting resin and a thermoplastic resin are used in combination as a matrix resin, and the above-mentioned experiment is performed. To provide a racket frame that has a moderate vibration damping rate, a moderate vibration damping rate, a stable ball striking surface, an in-plane rigidity, a light weight, and good operability. Is an issue.

[0013]

According to the present invention, there is provided a hollow racket frame made of a fiber reinforced resin, wherein the molding temperature is the same as that of the matrix resin in the same range as the matrix resin. Epoxy resin and thermoplastic R
Using IM nylon, the layer made of the above-mentioned thermosetting resin reinforced with fiber is used as the inner layer part, the layer made of the above-mentioned thermoplastic resin reinforced with fiber is used as the outer layer part, and the RIM nylon of the outer layer part is subjected to reaction injection molding. The racket frame is characterized in that the racket frame is provided.

The racquet frame is formed on the outer periphery of an inner layer member made of a laminate of a prepreg made of fiber-reinforced thermosetting epoxy resin or a thermosetting fiber-reinforced epoxy resin molded product. The fiber reinforced material is wound and placed in a mold, RIM nylon monomer is injected into the mold, and heated at a required temperature to cure the thermosetting resin of the inner layer member and to cure the RIM nylon. The polymer is produced by causing a polymerization reaction to occur in the monomer and curing it to form an outer layer using RIM nylon as a matrix.

The curing temperature (molding temperature) of the thermosetting epoxy resin is 120 ° C. to 150 ° C.
The molding temperature of M nylon is 130 to 150 ° C., which is almost the same. Therefore, a prepreg of an epoxy resin and a reinforcing fiber or a fiber-reinforced epoxy resin molded product is used as an inner layer member, and reinforcing fibers are laminated on the outer periphery thereof and placed in a mold.
When the IM nylon monomer is heated to, for example, 150 ° C., the thermosetting epoxy resin as the matrix resin of the inner layer member and the RIM nylon as the matrix resin of the outer layer member can be simultaneously molded. As described above, by using a thermosetting epoxy resin and a thermoplastic RIM nylon having molding temperatures in substantially the same range, the inner layer portion and the outer layer portion can be integrally molded at the same temperature in one mold. And the interfacial adhesion between the inner layer portion and the outer layer portion can be secured. Further, it is possible to prevent the thermosetting resin from being thermally degraded or deformed during molding of the thermoplastic resin.

A film or tube made of a thermoplastic resin may be interposed between the inner layer and the outer layer. When a film or tube made of such a thermoplastic resin is used, the melting point of the thermoplastic resin used as the film or tube is higher than the melting point of the thermoplastic resin in the outer layer portion.

That is, when the RIM nylon monomer flows in contact with the fiber-reinforced thermosetting epoxy resin in the mold, theoretically, when the epoxy resin is cured, no epoxy group remains, but in reality, the epoxy group does not remain. The group remains, and the polymerization catalyst of the RIM nylon monomer may react with the epoxy group and cause the polymerization inhibition of the RIM nylon itself. For this reason, as described above, it is preferable to coat a thermosetting epoxy resin with a film or tube made of a thermoplastic resin. In the adhesion between the thermoplastic resin film or tube and the thermosetting resin, strong adhesion is obtained because the thermosetting resin has good adhesiveness. Also, the interface of the film or tube is
A smooth surface, such as a film, facilitates the flow of the RIM nylon monomer and, further, when the RIM nylon is molded,
Since it is a homogeneous material, the adhesiveness is extremely improved.

Instead of interposing a film or tube made of a thermoplastic resin between the thermosetting resin and the thermoplastic resin, the following method does not cause polymerization inhibition of the RIM nylon monomer, and the interface between them does not occur. Can be improved in adhesiveness. That is, after a fiber-reinforced thermosetting epoxy resin is previously heat-molded, after-curing (reheating) is again performed, and crosslinking is advanced by the after-curing to reduce epoxy groups. Alternatively, the surface of the molded article is blasted or polished with abrasive paper to remove an epoxy resin-rich portion on the surface of the molded article, thereby reducing the amount of epoxy resin. In this way, by removing the epoxy resin appropriately, the chance of the RIM nylon monomer catalyst adhering to the epoxy group is reduced, so that a thermoplastic resin film or tube can be attached to the epoxy resin molded product. Even if the RIM nylon monomer is injected without coating, the RIM nylon monomer can be prevented from causing polymerization inhibition and the interfacial adhesion can be enhanced.

Further, when the fiber-reinforced thermosetting epoxy resin molded article is placed in a mold, an internal pressure is applied to the hollow part during RIM nylon molding in order to maintain the shape of the hollow part of the molded article. preferable. This is because even if the molded article has been cured, it is softened by heating and deformed by the injection pressure of the RIM nylon monomer, making it difficult to control the thickness of the RIM nylon portion. When the internal pressure is applied to the molded product as described above, the deformation of the molded product can be suppressed, and the thickness of the outer RIM nylon layer can be controlled as designed.

In the above racket frame, the entirety from the apex of the head portion to the grip end, or the apex portion of the head portion, a portion spaced 90 degrees from the apex centering on the center of the gut surface, and / or It is preferable that the amount of the thermoplastic resin in the outer layer portion is larger than the amount of the thermosetting resin in the inner layer portion at the central portion in the length direction of the racket frame from the apex of the portion to the throat portion from 120 degrees. 3).

As described above, since the outer layer portion made of thermoplastic RIM nylon is molded on the outer periphery of the fiber-reinforced thermosetting epoxy resin, the amount of the RIM nylon can be set arbitrarily in each part of the racket frame. It becomes possible. Specifically, by stacking an arbitrary number of fiber reinforced materials at arbitrary positions on the outer periphery of the fiber reinforced thermosetting epoxy resin, a fiber reinforced thermoplastic resin layer (fiber reinforced RIM nylon layer) is formed according to the thickness. Can be formed. This is because when the tube in the innermost layer of the fiber-reinforced thermosetting resin is pressed and molded, the molded wall thickness becomes proportional to the amount of the laminated reinforcing fibers.

As described above, since the thermoplastic resin is superior in the vibration damping property as compared with the thermosetting resin, the amount of the thermoplastic resin may be increased over the entire racket frame. It is preferable to locally increase the amount of the thermoplastic resin in a portion where the generation is likely to occur.

That is, in the racket frame, the primary vibration mode and the secondary vibration mode in the out-of-plane direction are shown in FIG.
2B, the primary vibration mode and the secondary vibration mode in the in-plane direction occur as shown in FIGS. 2A and 2B. Therefore, a vertex portion P1 of the head portion corresponding to a portion of the antinode where the vibration width of these vibration modes is large, and a portion P2 separated from the vertex by 90 degrees from the center of the center of the gut surface
(3 o'clock position if the vertex is 12 o'clock when the gut surface is the clock surface), and throat from 120 degrees (4 o'clock position if the vertex is 12 o'clock when the gut surface is the clock surface). In the central portion P3 in the length direction of the racket frame over the portion, the amount of the thermoplastic resin is increased. As described above, when the amount of the thermoplastic resin is locally increased in an effective portion in consideration of the vibration mode, the vibration damping property can be efficiently improved without causing an unnecessary increase in weight.

Further, in the central portion of the entire length of the racket frame from the top of the head portion to the grip end, the fiber angle of the reinforcing fiber may be set to 30 ° to 45 ° with respect to the longitudinal axis. Preferred (claim 4).

The actual behavior of the racquet frame during play is not divided into out-of-plane directions and in-plane directions, but shows a combined deformation behavior. Deformation behavior occurs.
When the fiber angle is set to 0 ° for the bending behavior, the bending stiffness is increased, and when the fiber angle is set to 90 ° for the buckling behavior, the buckling stiffness is increased. When the angle is set to 45 °, the torsional rigidity increases. Therefore, when the fiber angle at the central portion in the longitudinal direction of the racket frame where the deformation behavior of torsion occurs is set to 30 to 45 ° and the torsional rigidity is increased, vibration can be more effectively suppressed.

With the above configuration, the attenuation rate of the primary natural frequency in the out-of-plane direction in the equilibrium state at a temperature of 25 ° C. and a humidity of 60% is in the range of 0.7 to 0.9%. ). When the vibration damping rate is in the above range, as apparent from the above-described experimental results, the vibration damping rate is increased to such an extent that no tennis elbow is generated, and the response of the shot feeling is not slowed down, and the vibration damping rate is set to an appropriate value. be able to.

[0027]

Embodiments of the present invention will be described below.

The tennis racket frame of the first embodiment was manufactured by the following steps. First, in the first step, FIG.
As shown in (A), the mandrel core 1 of φ14 has 66
The nylon tube 2 is covered, and the 66 nylon tube 2 is covered with a prepreg (T800, manufactured by Toray Industries, Inc.) composed of a fiber made of epoxy resin as a thermosetting resin and carbon fiber.
P2053-12, resin content 30%) 3 were laminated to form a vertical laminate 4. The prepreg is
The fibers were laminated with the fiber angles of 0 °, 22 °, 30 ° and 90 °. The weight of the prepreg laminate 4 as the inner layer member A was 180 g.

In the second step, as shown in FIG. 3 (B), a 66 nylon film 5 made of a thermoplastic resin is applied to the entire outer peripheral surface of the inner layer member A made of the above-mentioned laminated body 4 with an overlapping margin of about 8 mm. Wound as.

In the third step, a glass fiber non-woven fabric (E.
PM-4-25) 6 is cut into a width of 30 mm, and FIG.
As shown in (C), it was continuously wound around a spiral. The number of layers of this spiral was two or three. The weight of the glass fiber nonwoven fabric 6 was 6 g.

In the fourth step, as shown in FIG. 3 (D), a braid made of carbon fibers woven in a sleeve shape (Carbon Braid BC7364-24 manufactured by Toho Rayon Co., Ltd.)
(20), BC7396-9 (20), BC7364
45 (20)) 7 are laminated on the outer peripheral surface of the top portion (top portion) P1 of the head portion of the racket frame, the 3 o'clock portion P2 of the head portion, and the portion P3 of the head portion that becomes a throat portion from 4 o'clock. did.

In the fifth step, as shown in FIG. 3 (E), the mandrel core material 1 is pulled out from the above-mentioned laminate, and
In a cavity 8a having a racket frame shape. The yoke portion 9 uses hard urethane foam as a core material, covers the core material with a 66 nylon tube, and further coats the outer peripheral surface of the yoke portion with the same carbon blade as the carbon blade 7. It was arranged in the cavity 8a.

In the sixth step, the temperature of the mold 8 was raised to 150 ° C., and 6 kgf / cm ² of pressurized air was supplied to the 66 nylon tube 2 constituting the innermost peripheral layer to hold it under pressure.
The epoxy resin of the prepreg 3 of the inner layer member A was cured by holding at 150 ° C. for 30 minutes.

In the seventh step, 30 minutes from the start of the sixth step.
After a lapse of minutes, a nylon monomer (UX-75, manufactured by Ube Industries, Ltd.) was injected into the cavity 8a. The melting temperature of the nylon monomer was 90 ° C., and a solution A containing a catalyst and a solution B containing an initiator were mixed at a ratio of 1: 1 and injected. The injection pressure was controlled at 5 kgf / cm ² . After holding for 3 minutes, the mold was released.

As shown in FIGS. 4 (A), 4 (B) and 4 (C), the tennis racket frame 11 manufactured by the above-described steps has an inner layer portion A made of an epoxy resin layer reinforced with carbon fibers as a whole. And an outer layer portion B made of a RIM nylon layer reinforced with a glass fiber nonwoven fabric, and a 66-nylon film 5 interposed therebetween to form an integrated structure. Also, the top P1 of the head portion 12 and the portion P at 3 o'clock
2. Part P applied to the throat part 13 from 4:00 of the head part
In FIG. 3, as shown in FIG. 4C, the outer layer B has a carbon blade 7 laminated on the outer periphery of the glass fiber nonwoven fabric 6, and the outer layer B has a large thickness. That is, the amount of the RIM nylon made of the thermoplastic resin in the outer layer portion is larger than the amount of the epoxy resin made of the thermosetting resin in the inner layer portion. The weight of the low frame of this tennis racket is 2
13 g. The racket frame has a cross-sectional shape of 22 mm in outer thickness and 12 mm in width, and has a gut area of 95 in ² . Note that the portion where the thickness is increased by laminating with carbon blades has the same outer shape and the thickness is greater than the other portions.

In the tennis racket frame of the second embodiment, the inner layer member A having the same structure as that of the first embodiment is previously heated at 150.degree. C. for 30 minutes to be hardened and molded. For 1 hour. Further, the outer peripheral surface of the reheated molded product of the inner layer member A was polished with water-resistant abrasive paper. In the racket frame of the inner layer member A formed as a molded product, three to four layers of nylon nonwoven fabric were spirally wound around the top portion and the 3 o'clock portion of the head portion. Further, two to three layers of carbon fiber plain woven cloth were laminated on the racket frame from the 5 o'clock portion to the throat portion. The fiber cloth was set such that the fiber angle was 45 ° in the axial direction. Thereafter, as in the first embodiment,
Manufactured by placing it in the mold cavity and injecting a nylon monomer. At that time, a flexible silicon tube was inserted into the hollow portion of the inner layer member A, and a pressure of ² kgf / cm ² was applied. The low frame of the tennis racket of the second embodiment manufactured by this method had the same shape as that of the first embodiment, and weighed 208 g.

In the tennis racket frame of the third embodiment, a glass fiber nonwoven fabric is spirally formed on the outer peripheral surface of the inner layer member having the same structure as that of the first embodiment along the entire length.
４4 layers wound. In the racket frame, no reinforcing fibers were arranged from the 3 o'clock portion and the 5 o'clock portion of the head portion to the throat portion. Otherwise, the tennis racket frame of the third embodiment was manufactured in the same manner as the first embodiment. The low frame of the tennis racket of the third embodiment had the same shape as that of the first embodiment, and weighed 216 g.

In order to compare the vibration damping rate, the top pressure rigidity (in-plane rigidity), the durability and the weight with the above embodiment of the present invention, the racket frame of the above embodiment has the same shape (thickness 22 m).
m, width 12 mm, gut area 95 in ² )
The tennis racket frames of the third to third comparative examples were manufactured.

The tennis racket frame of the first comparative example
This is a case where only a thermoplastic resin made of RIM nylon is used as the matrix resin. That is, carbon fiber blade (manufactured by Toho Rayon Co., Ltd.)
BC7364-24 (20), BC7364-45 (2
0)) to give a total of 110 g. In addition, the yoke material uses 5.0 g of hard urethane foam as a core material,
It was covered with a nylon tube, and its outer surface was covered with the above carbon fiber blade. Place these materials in the mold,
As in the first embodiment, the temperature of the mold was raised to 150 ° C., and a molten nylon monomer (UX-75 manufactured by Ube Industries, Ltd.) was injected into the cavity. Injection pressure is 3kgf / cm ²
And 3 kgf / cm ² in the 66 nylon tube
Internal pressure was applied. After holding for 3 minutes, the mold was released. The weight of the low frame of the first comparative example manufactured by the method is 226 g.
Met.

The tennis racket frame of the second comparative example
This is a case where only a thermosetting resin made of an epoxy resin is used as the matrix resin. A carbon fiber prepreg impregnated with an epoxy resin was laminated on a 66 nylon tube. These were placed in a mold, and the temperature was raised from room temperature to 150 ° C. while applying air pressure of 6 kgf / cm ^2.
For 30 minutes. The yoke portion was formed by using a polystyrene resin as a core material, winding a carbon fiber prepreg impregnated with an epoxy resin around the core material, arranging the prepreg in a mold, and simultaneously molding. The weight of the low frame of the second comparative example was 220 g.

The tennis racket frame of the third comparative example is
The present embodiment is the same as the first embodiment except that the nylon 66 is removed between the first embodiment and the prepreg of the inner layer member and the glass fiber nonwoven fabric wound around the outer periphery. That is, the case where no thermoplastic film was interposed between the inner layer portion using the thermosetting resin as the matrix resin and the outer layer portion using the thermoplastic RIM nylon as the matrix resin. Of the low frame was 211 g.

The low frame weights of the first to third embodiments and the first to third comparative examples are as described above, and are also shown in Table 1 below. As indicated by * in Table 1, these weights were obtained after molding and kept at a temperature of 23 ° C. and a humidity of 55% for 90 hours. In contrast, a temperature of 32.5 ° C. and a humidity of 9
The low frame weight was measured when the sample was kept at 0% for 200 hours (at the time of tempering). The results are as shown in Table 1. In Table 1, in each of the first to third embodiments and the first to third comparative examples, three racket frames are prepared, and the average value is obtained.

[0043]

[Table 1]

In the first embodiment, 213 g is 2 at the time of humidity control.
It was 14 g, and only 1 g increased. The increase was 1 g in the second embodiment and 2 g in the third embodiment. On the other hand, in the first comparative example using only the thermoplastic resin as the matrix resin, 226 g was changed to 231 g and increased by 7 g. As described above, when only the RIM nylon made of a thermoplastic resin is used as the matrix resin, the weight changes due to environmental changes and the environmental dependency increases. However, as in the present invention, the matrix resin of the inner layer portion is thermally cured. As in the second comparative example using only a thermosetting resin as the matrix resin, the increase in weight during tempering is 1 g to 2 g.
It was confirmed that environmental dependency can be reduced.

Further, the racket frames of the first to third embodiments and the first to third comparative examples were held at a temperature of 23 ° C. and a humidity of 55% for 90 hours after molding as indicated by *, and The vibration damping rate was measured separately for the tempering.

As shown in FIG. 5, the method of measuring the vibration damping rate is as follows.
Attach the ball to the center of the gut surface at a speed of 35 m / sec. Attach the ball to the center of the gut surface at a speed of 35 m / sec. Received and calculated the vibration damping rate from the vibration damping waveform.

As shown in Table 1, when held under the condition of 23 ° C. and 55% of *, the racket frames of the first to third embodiments have a vibration damping ratio of 0.81 to 0.71.
The target of the present invention is in the range of 0.7 to 0.9%, the vibration damping rate is not too small, the occurrence of tennis elbow and the like can be suppressed, and the response of the shot feeling is not too large. Sex does not become dull. On the other hand, in the second comparative example in which the matrix resin is only a thermosetting resin, the vibration damping rate is too small at 0.43, so that tennis elbow or the like is easily generated, and the matrix resin is made of thermoplastic resin. In the first comparative example in which only the resin RIM nylon was used, the vibration damping rate was slightly too large at 0.92%.

Looking at the vibration damping rate during tempering,
In the third to third embodiments, the respective vibration damping rates are high, but 0.86% to 0.77%, which is within the target range of the present invention. On the other hand, in the first comparative example, 0.92
→ The value greatly increased to 1.25, the vibration damping rate became too high, and the response of the shot feeling was extremely poor. Further, in the second comparative example, the vibration damping rate was changed from 0.43 to 0.45.
Although it is slightly higher, it is much lower than the appropriate vibration damping rate.

Further, the racket frames of the first to third embodiments and the first to third comparative examples were held for 90 hours at a temperature of 23 ° C. and a humidity of 55% after the molding indicated by *, The top pressure stiffness was measured separately for the tempering.

The above-mentioned top pressure rigidity corresponds to the in-plane direction rigidity. The method of measuring the top pressure rigidity is as shown in FIG.
The racket 11 is arranged so that the gut surface is horizontal, and in this state, a load of 80 kgf / cm ² is applied from above to the center point P between the top of the head portion and the grip end by the pressurizing tool 25, and the amount of deflection is set. The spring constant was determined from.

As shown in Table 1, when held under the condition of 23 ° C. and 55% of *, the top pressure rigidity of the first embodiment is 140
kgf / cm ^2, in the second embodiment are larger and 147kgf / cm ^2, the apex of the head portion, 3 o'clock, in the third embodiment were not additionally arranging the reinforcing fibers toward 5:00 - throat, 122kgf / cm ² and it is slightly smaller, the present invention is in the range from 100~150kgf / cm ² as a target. On the other hand, when the matrix resin of the first comparative example is made of only the thermoplastic resin RIM nylon, 10
It is slightly smaller, ² kgf / cm ² . The third comparative example was 124 kgf / cm ² , and was different only in that a thermoplastic film was not interposed between an inner layer portion using a matrix resin as a thermosetting resin and an outer layer portion using a matrix resin as a thermoplastic resin. Compared to the first embodiment, the rigidity at the top pressure was lower by 16 kgf / cm ² , and it was recognized that the lower interface strength between the inner and outer layers affected the lowering of the rigidity.

On the other hand, at the time of refining, the rigidity of the top pressure is decreased in both the embodiment and the comparative example. In the embodiment, the decrease width is relatively small as 4 to 7 kgf / cm ² , but in the first comparative example. 15 kgf / cm ² even decreased 87kgf / cm ^2, and the smaller than 100 kgf / cm ² of the present invention is a target, the stability of the ball striking face is deteriorated. In addition, the third comparative example is also 11 kgf /
cm ² was also reduced, 26 kgf / cm ² was smaller than in the first embodiment, and the difference was further increased.

Further, the first to third embodiments and the first embodiment
An impact durability test was performed on the racket frames of the third to third comparative examples. In the impact durability test, the grip portion of the racket was gripped with a cushioning material and chucked, and the top of the yoke on the gut surface was 40 m / s.
ec hit the ball. The destruction state of the racket due to the collision of the ball was measured.

The results of the impact durability test are shown in Table 1. In each of the first, second, and third examples, the ball was not broken even after hitting the ball 200 times. On the other hand, in the third comparative example using only the thermoplastic resin as the matrix resin, the ball was broken only by hitting the ball 12 times.

Further, regarding the adhesive strength at the interface between the fiber-reinforced thermoplastic resin and the fiber-reinforced thermosetting resin, the following fourth embodiment of the present invention and a fourth comparative example were prepared, and the adhesive strength was compared. It was measured.

In the fourth embodiment, ten layers of prepreg of epoxy resin fiber and carbon fiber are used, and fiber angles of 0 ° and 9
0 ° alternately. This laminate was press-molded under heating at 150 ° C. under a pressure of 7 kgf / cm ² for 40 minutes to form a 1 mm-thick rectangular plate. Further, the plate material was annealed at 180 ° C. for 2 hours. Thereafter, one side of the sample was polished, and placed in a mold cavity with a carbon fiber cloth laminated on the polished surface, and RIM nylon monomer was injected. The sample was manufactured by molding at a mold temperature of 150 ° C. and an injection pressure of 5 kgf / cm ² for 5 minutes. The shape of the sample is as shown in FIG. 6, where 30 is a portion made of a fiber-reinforced thermosetting resin using epoxy resin as a matrix resin, 31 is a thermoplastic resin portion made of RIM nylon, 32 is an adhesive surface, and its length is The length is set to 10 mm. This sample was cut into a strip having a width of 10 mm to prepare a test piece.

In the fourth comparative example, 10-layer carbon fiber plain woven cloth is laminated, the laminated body is placed in a mold, RIM nylon monomer is injected, and a 1 mm thick plate material made of fiber-reinforced thermoplastic resin is used. Was molded. As in FIG. 6, one end of one surface of the plate material was used as an adhesive surface having a length of 10 mm, and the adhesive surface was polished. A prepreg made of an epoxy resin fiber was laminated on the adhesive surface and press-molded at a pressure of 7 kgf / cm ² . This test piece is set to a width 1 as in the fourth embodiment.
A test piece was prepared by cutting into a 0 mm strip shape.

With respect to the test pieces of the fourth embodiment and the fourth comparative example, both ends of the thermoplastic resin portion 30 and the thermosetting resin portion 31 were chucked, and the test speed was 1 mm.
The adhesion test was performed by pulling in the opposite direction at / min.

The results are shown in Table 2 below. The adhesive strength of the fourth embodiment of the present invention is 413 kgf / cm ² , whereas the adhesive strength of the fourth comparative example is 49 kgf / cm ² . It was confirmed that the adhesive strength of the embodiment of the present invention was much higher than that of the comparative example.

[0060]

[Table 2]

[0061]

As apparent from the above description, according to the present invention, a thermosetting resin excellent in strength and rigidity and a thermoplastic resin excellent in vibration damping and impact resistance are provided. Since both are used as the matrix resin, without increasing the weight by using an extra thermoplastic resin, the molded racket frame has a moderate degree that does not generate tennis elbow and does not slow down the response of the shot feeling. It is possible to provide a vibration damping rate, and furthermore, it is possible to provide appropriate in-plane rigidity to stabilize the hitting surface.
That is, it is possible to provide a racket frame which is lightweight, has high stability and durability of a hitting surface, and has an appropriate vibration damping property.

In particular, in the present invention, since the molding temperature of the thermosetting resin and the thermoplastic resin to be used is substantially in the same range, the thermosetting resin may undergo thermal degradation or deformation at the molding temperature of the thermoplastic resin. Without doing so, an integrated racket frame that can be molded simultaneously in the same mold and that has a high interface adhesive force can be molded.

Further, since the inner layer is made of a thermosetting resin and the outer layer is made of a thermoplastic resin, the amount of the thermoplastic resin can be easily adjusted. As a result, the amount of the thermoplastic resin is locally increased in a portion where the vibration width increases, and the vibration damping performance can be efficiently improved. Therefore, as described above, the vibration damping property can be improved without using an extra thermoplastic resin, and the weight of the racket frame can be reduced. Furthermore, when the fiber angle of the reinforcing fiber at the center in the length direction of the racket frame is set to 45 ° with respect to the axial direction having high torsional rigidity, vibration can be more effectively suppressed, and from this point, heat can be suppressed. It is possible to further reduce the weight by reducing the amount of the plastic resin.

[Brief description of the drawings]

FIGS. 1A and 1B are schematic diagrams showing an out-of-plane vibration mode of a racket frame.

FIGS. 2A and 2B are schematic diagrams showing an in-plane vibration mode of a racket frame.

FIGS. 3A to 3E are schematic manufacturing process diagrams of the racket frame according to the first embodiment of the present invention.

FIG. 4 shows a racket frame of the first embodiment,
(A) is a plan view, (B) is a sectional view taken along line BB of (A),
(C) is a sectional view taken along line CC of (A).

FIG. 5 is a schematic view showing a method of measuring a vibration damping rate.

FIG. 6 is a schematic view showing a method of measuring a top pressure rigidity.

FIG. 7 is a schematic view showing a method for measuring an adhesive strength.

[Explanation of symbols]

Reference Signs List A inner layer member B outer layer member 11 racket frame 12 head portion 13 throat portion P1 vertex portion of head portion P2 3 o'clock portion of head portion P3 central portion in the length direction of racket frame from 4 o'clock portion of head portion to throat portion

Continued on the front page (51) Int.Cl. ⁶ Identification code FI // B29K 77:00 B29L 31:52

Claims (6)

[Claims] 1. A hollow racket frame made of a fiber-reinforced resin, wherein the thermosetting epoxy resin and the thermoplastic RIM nylon having the same molding temperature as the matrix resin are used, and the fiber-reinforced thermosetting resin is used. A racket frame, wherein a layer made of a conductive resin is used as an inner layer, a layer made of the above-mentioned thermoplastic resin reinforced as a fiber is used as an outer layer, and RIM nylon of the outer layer is formed by reaction injection molding. 2. A thermoplastic film or tube is interposed between the inner layer and the outer layer.
Racket frame described in. 3. The entire lengthwise direction from the top of the head to the grip end, or the top of the head,
A part 90 degrees away from the vertex with the center of the gut plane as the center point, and / or 1 part from the vertex of the head.
3. The amount of the thermoplastic resin in the outer layer portion is larger than the amount of the thermosetting resin in the inner layer portion at a central portion in the length direction of the racket frame from the position of 20 degrees to the throat portion. Racket frame described in. 4. The fiber angle of the reinforcing fibers in the central portion of the entire length of the racket frame from the apex of the head portion to the grip end is set to 30 ° to 45 ° with respect to the longitudinal axis. The racket frame according to any one of claims 1 to 3. 5. The method according to claim 1, wherein an attenuation rate of an out-of-plane primary natural frequency in an equilibrium state at a temperature of 25 ° C. and a humidity of 60% is 0.7 to 0.9%. Racket frame according to the item. 6. A mold in which a fiber reinforced material is wound around an outer periphery of a laminate of a prepreg made of a fiber-reinforced thermosetting epoxy resin or an inner layer member made of a thermosetting epoxy resin molded product. The RIM nylon monomer is poured into the mold, heated at a required temperature to cure the thermosetting resin of the inner layer member, and causes a polymerization reaction to occur in the nylon monomer to cure the RIM nylon. A method of manufacturing a racket frame, wherein an outer layer portion serving as a matrix is formed.