JPH10151692A - Fiber reinforced plastic product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the close adhesiveness of a core member and an FRP outer shell excellent to prevent the generation of unpleasant vibration or sound by constituting the core member of a fiber-containing foamed resin. SOLUTION: An FRP product has a core member 1 composed of a foamed resin containing fibers 2 and the FRP outer shell 4 formed to the periphery of the core member 1. Herein, the fibers 2 are added to the core member pref. in an amt. of 3-50wt.%, more pref., 5-10wt.%. The foamed resin constituting the core member is composed of a vinylidene chloride resin, an epoxy resin or a phenol resin. Especially, the vinylidene chloride resin is pref. The bulk density of the core member is pref. 0.03-0.5g/cm<2> , more pref. 0.1-0.3g/cm<3> .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber reinforced plastic (FRP) which can be used for tennis rackets and the like.
About the product.

[0002]

2. Description of the Related Art The manufacture of FRP tennis rackets, for example, has conventionally been performed, for example, by the following method. That is, a. A method in which a preform obtained by winding a prepreg containing reinforcing fibers such as carbon fibers around a flexible tube such as a nylon tube is placed in a mold and molded while pressurizing the inside of the flexible tube (JP-A-5-96030). No.).

B. Put the preform obtained by winding the prepreg around the core made of foamed resin in a mold,
Heat and pressure molding method.

C. A method in which a preform obtained by winding the prepreg around a core made of a foamable resin is placed in a mold, heated, and molded by utilizing the foaming pressure of the resin caused by the heating.

D. A method in which a preform formed by wrapping a reinforcing fiber around a flexible tube is placed in a mold, heated while pressurizing the inside of the flexible tube, and resin is injected into the mold to form the mold.

[0006] Among these methods, in the method (b), a urethane foamed resin, an acrylic foamed resin, a polyethylene foamed resin or the like is used as a core. Also, c
In the above method, a polystyrene-based resin or a polyethylene-based resin containing a foaming agent is used as the core.
Also, in the methods a and d using a flexible tube, the methods b and c are also used for forming the yoke because it is difficult to pressurize the inside of the flexible tube.

Here, epoxy resin, polyester resin, nylon resin and the like are used as the matrix resin of the FRP.
00-230 ° C. In FRP products,
In some cases, post-curing treatment is performed for the purpose of improving the complete curing and physical properties of the matrix resin. In this treatment, for example, when an epoxy resin is used as the matrix resin, heating is performed at about 150 ° C. for about 2 hours.

The above-mentioned foamed resin core and foamable resin core have a maximum operating temperature of about 100 ° C., and therefore contract due to heat during molding and post-curing. For this reason, there is a problem that voids are formed between the outer shell of the FRP and the physical properties of the product are deteriorated, and the contracted core body moves during use to generate unpleasant vibrations and sounds.

In order to solve such a problem, in the invention of Japanese Patent Application Laid-Open No. 5-228228, a rigid foamed polymethacrylimide resin is used as a core. Since the polymethacrylimide resin has a high heat resistance temperature of 150 to 200 ° C., there is almost no concern about the above-mentioned heat shrinkage. However, on the other hand, hard foamed polymethacrylimide resin is difficult to shape at the same time as molding, so it must be processed in advance to a desired shape by punching or cutting, and because it is hard, There is a problem that processing itself is difficult or bubbles are destroyed by processing.

Therefore, the invention of Japanese Patent Application Laid-Open No. 6-105932 has solved such a drawback by using a foamed polyester resin for the core. However, this method involves extruding and foaming a polyester resin to form a foam sheet, cutting the foam sheet, and re-foaming the foam sheet in a mold in advance to shape it into a core shape. Required, and the work efficiency is poor and the cost is high.

On the other hand, Japanese Patent Laid-Open No. 7-323099 discloses that
A method has been proposed in which a thermoplastic resin containing a foaming agent is inserted into a bag and used. However, in this method, at the time of molding, it is difficult to completely fill the bag body with the resin because the pressure of the gas generated from the air or the foaming agent trapped in the bag body and the foaming pressure of the resin are balanced. Voids are created in the bag, causing the same disadvantages as described above due to heat shrinkage. Such a disadvantage is not apparent from the appearance because the material itself forming the FRP shell is pressed against the wall of the mold by the pressure of the gas in the bag and the foaming pressure of the resin.

[0012]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned various problems in the prior art, and it is an object of the present invention to improve the adhesion between the core and the FRP outer shell. An object of the present invention is to provide an FRP product which is excellent in that it is less likely to generate unpleasant vibrations and sounds, and which is excellent in physical properties such as strength.

[0013]

In order to achieve the above object, the present invention provides an FRP having a core of a foamed resin containing fibers.
Provide products. The fiber is preferably contained in the core in the range of 3 to 50% by weight, and is preferably in the form of a nonwoven fabric. The foamed resin is preferably a vinylidene chloride resin. The dimensional change of the core at 150 ° C. is preferably positive. Further, the bulk density of the core is preferably in the range of 0.03 to 0.5 g / cm ³ . Typical applications to which the FRP product of the present invention is applied include rackets such as tennis rackets and badminton rackets.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, an FRP product has a core 1 made of a foamed resin containing fibers 2 and an FRP outer shell 4 formed around the core 1. In this example, the flexible tube 3 is interposed between the core body 1 and the outer shell 4, but remains after molding due to the production method described later, and is used as an FRP product. Not necessary.

Such an FRP product can be manufactured, for example, as follows. That is, first, a fiber and a resin containing a foaming agent are sealed in a flexible tube, for example, a nylon tube or a rubber tube, and a prepreg containing reinforcing fibers around the flexible tube, for example, a unidirectional prepreg or woven fabric The prepreg is wound to form a preform. Next, the preform is placed in a mold, heated to foam the resin, and molded using the foaming pressure of the resin.

FIG. 2 shows an FRP tennis racket using the FRP product shown in FIG.
The face part 5, the shaft part 7, and the grip part 8 are the core 1
, And has a hollow structure of a flexible tube 3 and an outer shell 4 made of FRP.

In the above, the core is used as a strength member,
In addition to acting as a vibration absorbing member, in the molding process, it acts as a pressurizing medium for pressing the outer shell molding material against the wall surface of the mold.

The fibers contained in the core are made of organic fibers such as polyester fibers, nylon fibers and aramid fibers, and inorganic fibers such as carbon fibers and glass fibers. These may be in the form of a fiber, but are preferably used in the form of a nonwoven fabric or a woven fabric, especially a nonwoven fabric. When used in the form of a non-woven fabric, the non-woven fabric has a lot of minute spaces inside, so that the gas generated at the time of foaming can be effectively subdivided, and the foamed resin enters between the fibers well and becomes more uniform with the resin. Composite can be achieved.

Such fibers are preferably contained in the core in an amount of 3 to 50% by weight. A more preferred range is from 5 to 10% by weight. If it is less than 3% by weight, the above-mentioned effects cannot be expected much. On the other hand, if it exceeds 50% by weight, voids due to insufficient resin are likely to be formed.

The foamed resin constituting the core is made of a vinylidene chloride resin, an epoxy resin, a phenol resin or the like. Above all, vinylidene chloride-based resin has excellent heat resistance and can be made to contain a foaming agent.
Since foaming can be performed in a wide temperature range of 0 ° C. to 230 ° C., the range of choices of the matrix resin used for the outer shell molding material is widened, and there is almost no heat shrinkage at the time of molding or post cure treatment. .

Preferably, the core has a bulk density in the range of 0.03 to 0.5 g / cm ³ . A more preferable range of the bulk density is 0.1 to 0.3 g / cm ³ .
If the bulk density is less than 0.03 g / cm ³ , the compressive strength of the core may be insufficient. On the other hand, if it exceeds 0.5 g / cm ³ , the weight increases, and if the weight of the product is the same, the thickness of the outer shell must be reduced and the physical properties of the product deteriorate, which is not preferable.

The core preferably has a positive dimensional change at 150 ° C. Even if such a core body is divided by a later drilling process or the like, it becomes possible to fill the internal voids by re-foaming by a post-curing process.

As the reinforcing fibers constituting the FRP outer shell,
High strength such as carbon fiber, glass fiber, polyaramid fiber,
High modulus fibers can be used. They may be in the form of a fiber or a fabric such as a woven fabric. In addition, as the matrix resin, a thermosetting resin such as an epoxy resin, an unsaturated polyester resin, a vinyl ester resin, and a phenol resin, and a thermoplastic resin such as a nylon resin and a polyethylene resin can be used.

The FRP outer shell may be formed by molding a core obtained by winding a prepreg around a core as a preform, or by winding a reinforcing fiber around the core using a filament winding method or the like. A method called RIM molding (reaction injection molding) or RTM molding (resin transfer molding), in which a preform is put into a mold and a resin is injected into the mold, may be used.

[0025]

【Example】

Example 1 An FRP product shown in FIG. 1 was manufactured. That is, a polyester nonwoven fabric having a basis weight of 175 g / m ² and a thickness of about 3 mm, and a particle size of about 15 including isobutane as a blowing agent.
μm vinylidene chloride-based resin particles are sealed in a nylon tube so that the polyester non-woven fabric is 7% by weight.
Around the nylon tube, 12 layers of a unidirectional prepreg made of carbon fiber as a reinforcing fiber and epoxy resin as a matrix resin are wound 12 layers so that the direction of the carbon fibers forms an angle of 60 ° between layers to form a preform. did.

Next, the preform is placed in a mold, and
The molding was performed while heating at 50 ° C. for 30 minutes to foam the vinylidene chloride resin.

Thus, an FRP product having a carbon fiber reinforced plastic outer shell formed around a core made of a foamed vinylidene chloride-based resin containing a polyester nonwoven fabric through a nylon tube was obtained. This FRP product was excellent in surface quality, excellent in adhesion between the core and the outer shell, and high in compressive strength.

Example 2 A tennis racket shown in FIG. 2 was manufactured. That is, the basis weight is 175 g / m ² and the thickness is about 3
mm polyester nonwoven fabric and vinylidene chloride resin particles having a particle size of about 15 μm containing isobutane as a foaming agent are enclosed in a nylon tube so that the polyester nonwoven fabric is 7% by weight, and carbon fibers are wrapped around the nylon tube. Four layers of unidirectional prepregs each having reinforcing fibers and epoxy resin as a matrix resin such that the directions of the carbon fibers are three directions of 0 °, 30 °, and -30 ° with respect to the axial direction of the nylon tube, A preform A for forming the yoke 6 by winding a total of 18 layers of 7 layers and 7 layers was obtained.

On the other hand, a unidirectional prepreg having carbon fibers as reinforcing fibers and an epoxy resin as a matrix resin is placed in a nylon tube so that the direction of the carbon fibers is 0 °, 30 °, -30 ° with respect to the axial direction of the nylon tube. A total of 18 layers of four layers, seven layers, and seven layers were wound in three directions of ゜ to obtain a preform B for forming the face part 5, the shaft part 7, and the grip part 8.

Next, the two types of preforms A and B are placed in predetermined positions in a racket-shaped mold, and heated at 150 ° C. for 25 minutes while pressurizing the inside of the nylon tube of the preform B with compressed air. I got a racket frame. Furthermore, after machining the gut hole in the racket frame, 15
Post cure treatment was performed at 0 ° C. for 2 hours.

In the tennis racket thus obtained, the yoke portion has a core made of a polyester nonwoven fabric and a vinylidene chloride resin, an outer shell made of carbon fiber reinforced plastic, and interposed between the core and the outer shell. It is made of nylon tube, fitted with gut, 180km
Even after subjected to a durability test in which 300 tennis balls hit at a speed of / h were hit, no vibration or sound was generated from the yoke portion. The yoke was cut and observed, but no thinning or splitting of the core was observed.

Comparative Example A tennis racket was obtained in exactly the same manner as in Example 2 except that the polyester nonwoven fabric was not used for the preform A.

The resulting tennis racket produced sound at the yoke. When I cut the yoke and examined it,
It was found that the inside was not sufficiently filled even by foaming at the time of molding, and the core body was divided at the time of forming the gut hole, and the pieces moved by the corresponding amount inside the yoke portion.

Example 3 In Example 2, vinylidene chloride-based resin particles having a particle diameter of about 1 mm and containing a fluorocarbon-based gas as a foaming agent were used for the preform forming the yoke portion. Even after the resin is foamed so as to have a bulk density of 0.04 g / cm ³ , the resin has a length of about 4 at 150 ° C.
% Of positive dimensional change.

After the molding, the gut holes are processed, and the
After a post-curing treatment at 2 ° C. for 2 hours, the yoke was cut and observed, and the inside was completely filled with resin.

[0036]

The FRP product of the present invention uses a foamed resin containing fibers as a core, and as shown in the examples, has excellent adhesion between the core and the FRP outer shell and is uncomfortable. There is little fear of generating undesired vibrations and sounds, and it is excellent in physical properties such as strength.

[Brief description of the drawings]

FIG. 1 is a perspective view of an FRP product according to one embodiment of the present invention.

FIG. 2 is a front view of a tennis racket using an FRP product according to one embodiment of the present invention.

[Explanation of symbols]

 1: resin foam 2: fiber 3: flexible tube 4: FRP outer shell 5: face 6: yoke 7: shaft 8: grip

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B32B 27/34 B29C 67/14 P // B29K 27:00 77:00 105: 04 105: 08 B29L 31:52

Claims (7)

[Claims] 1. A fiber-reinforced plastic product having a core of a foamed resin containing fibers. 2. The fiber reinforced plastic product according to claim 1, wherein the fiber content in the core is in the range of 3 to 50% by weight. 3. The fiber according to claim 1, wherein the fibers are in the form of a non-woven fabric.
Or the fiber-reinforced plastic product of 2. 4. The fiber reinforced plastic product according to claim 1, wherein the foamed resin is a vinylidene chloride resin. 5. The fiber reinforced plastic product according to claim 1, wherein the dimensional change of the core at 150 ° C. is positive. 6. A core having a bulk density of 0.03 to 0.5 g / c.
is in the range of m ^3, fiber reinforced plastic product according to claim 1. 7. The fiber-reinforced plastic product according to claim 1, which is a racket.