JP2002103463A - Tubular molding, shaft and pole for golf club using the molding, and method for manufacturing tubular molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tubular material having uniform rigidity distribution in a circumferential direction by eliminating an irregular thickness and an unevenness of a reinforcing fiber density in the circumferential direction and a method for efficiently manufacturing such a tubular material by a simple method. SOLUTION: Fibers are stretched in the circumferential direction of a mandrel (10), and a prepreg (2a) is wound in one circle. The fibers are stretched at its outside in a longitudinal direction, a prepreg (3a) is wound in one or more circles. Fibers are stretched at the winding edge in the longitudinal direction, and another prepreg (3b) is wound so as to substantially dispose a starting winding edge of the head prepreg (3a) and an ending winding edge of the other prepreg (3b) on the same longitudinal section along the longitudinal direction of the molding. The another prepreg (3b) has a resin content of 1.1 to 1.4 times as large as that of the prepreg (3a) and has the same thickness as that of the prepreg (3a). Further, after the fibers are stretched at its outside in the circumferential direction and a prepreg (4a) is wound in one cycle, the resin is cured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various types of rod-shaped bodies such as fishing rods and clothes-drying rods, various types of tubular molded bodies used for golf shafts, tennis rackets, and the like, and a method for producing the same.
More specifically, the present invention relates to various tubular molded bodies manufactured using a prepreg obtained by impregnating a reinforcing fiber with a matrix resin, and a method for manufacturing the same.

[0002]

2. Description of the Related Art A composite material using various reinforcing fibers such as carbon fiber as a reinforcing material is lightweight, and has excellent strength and elastic modulus. Applications have been developed and put to practical use in a wide range of fields as components for space aircraft.

For example, when manufacturing various tubular molded bodies such as fishing rods and golf shafts from a composite material, usually, a prepreg in which a matrix resin is impregnated with reinforcing fibers is wound around a mandrel, and a PP tape is placed thereon. After being wound and stabilized, it is heated in a heating furnace to cure the resin, and then cooled to remove the mold and remove the PP.
Do tape. Thereafter, processes such as polishing and various kinds of painting are performed according to the application.

Incidentally, in the case of the above-mentioned tubular molded body, since the strength in the length direction and the circumferential direction is particularly important, it is necessary to extend the reinforcing fibers in these two directions. Generally, a prepreg used for a tubular molded product is obtained by impregnating a matrix resin into reinforcing fibers aligned in one direction. For this reason, the reinforcing fibers are provided in the tubular molded body in the longitudinal direction (0 °).
), And a prepreg layer wound so that the reinforcing fibers are oriented in the circumferential direction (90 ° direction) of the tubular molded body.

[0005] Particularly, a structure that can obtain a high-strength tubular molded body includes an innermost layer in which a reinforcing fiber is wound around in a direction of 90 °, an intermediate layer in which a reinforcing fiber is wound a plurality of times in a direction of 0 °, and a reinforcing layer. There is known a tubular body having a three-layer structure including an outermost layer in which the fiber is wound once in a direction of 90 °.

Here, the intermediate layer is formed by winding the prepreg two or more times in order to obtain a sufficient thickness. However, if one prepreg is wound plural times, the circumferential direction of the tubular body may be increased due to wrinkles or the like. In some cases, the thickness of the intermediate layer may change. In particular, in the case where the shaped body is tapered such that the diameter gradually increases in the length direction, even if the fiber is oriented at 0 ° at the beginning of winding of the prepreg, the fiber is inclined at the end of winding. As a result, the strength in the length direction of the tubular body becomes insufficient.

Therefore, for example, in a fishing rod disclosed in Japanese Patent Application Laid-Open No. 55-74739, a single prepreg sheet is used for each round to wind the plurality of rounds so that the direction of the fiber in each round is 0 °. Keep in the direction of.

However, in this case, it is difficult to cut the prepreg such that the winding start edge and the winding end edge of the prepreg sheet every one turn exactly coincide with each other. The winding end edge may partially overlap. Due to this overlap, the thickness of the obtained molded body is locally increased, and a portion where the fiber density is locally high is formed, which not only reduces the surface smoothness but also increases the strength in the circumferential direction. Variations occur.

In order to eliminate this variation, for example, in a tubular body disclosed in Japanese Patent Application Laid-Open No. 10-291265, the reinforced fiber has a prepreg in the direction of 0 ° every one revolution.
When winding the sheet, a plurality of rounds, and winding, the dimension is intentionally shortened so that the desired opening is formed without overlapping the winding start edge and the winding end edge of the first prepreg sheet. A second prepreg sheet is wound on the outer peripheral surface such that the edges overlap at the position of the first opening.

When the prepreg wound in this manner is cured by heating, the matrix resin and fibers of the polymerized portion of the prepreg sheet on the outer peripheral side flow into the openings of the prepreg on the inner peripheral side, and It is stated that since the insufficient resin and fiber can be supplemented by the openings, the obtained tubular body can be prevented from changing its thickness in the circumferential direction.

By the way, in recent years, prepregs having a resin content of 25% or less have been used for tubular moldings such as fishing rods due to various advances in techniques for reducing the content of matrix resin in prepregs.

[0012]

By using the prepreg having a small amount of surplus resin, the above-mentioned JP-A-10-2912 is used.
As disclosed in Japanese Patent Publication No. 65, when a molded article is to be produced by utilizing the flow of resin and fibers in a molding step of curing the resin, the amount of flowing resin is reduced in a prepreg having a small resin content. Therefore, the fluidity of the fibers generated simultaneously with the flow of the resin also decreases. as a result,
Irregularities due to the steps of the prepreg are conspicuous on the surface of the tubular molded body. Due to this decrease in surface smoothness, the coating is uneven and the quality of the product is also reduced. In addition, the density of the fibers in the circumferential direction of the molded body also becomes uneven, which causes a problem that the rigidity distribution in the circumferential direction is greatly changed.

Further, depending on the use of the molded article, when the coil is wound according to a conventionally used winding pattern in which the tip is wound twice around the tip and the hand is wound around three times, the center part is wound around two and a half times. Since the number of windings is odd, the number of windings of all the layers should be equal to each other as described in JP-A-10-29.
1 per cycle as disclosed in US Pat.
The method of winding two prepreg sheets cannot be adopted.

Further, even in the above-mentioned Japanese Patent Application Laid-Open No. Hei 10-291265, it is necessary to make the dimensions of the opening portion of the first sheet and the overlapping portion of the second sheet coincide with each other. Must be cut to size. As described above, many small prepreg sheets cut to precise dimensions must be prepared, and the production efficiency is reduced. In addition, since it is necessary to wind the prepreg in the second round so that the position of the opening portion and the position of the overlapping portion are accurately matched, the operation becomes complicated, and the operation efficiency is significantly reduced.
Further, since it is necessary to wind a relatively expensive thin prepreg in multiple layers, the loss portion increases, which also affects the price.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has as its object to reduce the thickness deviation in the circumferential direction and the dispersion of the reinforcing fiber density, and to provide a tube having a substantially uniform rigidity distribution in the circumferential direction. An object of the present invention is to provide a molded article and a production method capable of producing such a tubular molded article in a simple manner and with high efficiency.

[0016]

In order to achieve the above object, the present invention according to claim 1 is a tubular molded body made of a fiber-reinforced composite material, wherein the tubular molded body has a density and a bending rigidity of a reinforcing fiber in a circumferential direction. It is characterized in that the distribution is substantially uniform. As described above, since the tubular molded body in which the distribution of the density and the bending rigidity of the reinforcing fibers in the circumferential direction is substantially uniform has no directionality in the strength, even when finishing into a product such as a golf shaft or a fishing rod, the circumferential direction of the formed body is not limited. It can be manufactured without considering characteristics, and can be used in any orientation, thereby improving manufacturing efficiency and usability. In addition, since various products using the tubular molded body have uniform strength, bending and strain are uniform, and the quality is excellent. Furthermore, there are no locally vulnerable parts and the safety in use is high.

Further, such a tubular molded body having a distribution of the reinforcing fibers having a substantially uniform distribution in the circumferential direction and a substantially uniform distribution of the bending stiffness in the circumferential direction can be used for various purposes. In particular, the inventions according to Claims 2 and 3 are a shaft and a rod for a golf club, comprising the tubular molded body according to Claim 1.

In order to manufacture the above-mentioned tubular molded article, the invention according to claim 4 of the present invention relates to a tubular article obtained by winding a prepreg around a mandrel into a plurality of layers at a required fiber angle and then curing the prepreg. In the method for producing a molded body, the prepreg (P1) wound around one or more turns by orienting the fibers in the longitudinal direction of the tubular molded body, substantially in the same direction as the prepreg (P1) The winding start edge of the other prepreg (P2) in which the fiber is oriented is arranged in abutting state, and the winding start edge of the preceding prepreg (P1) and the winding end of the other prepreg (P2) And winding the edge so as to be substantially arranged on the same vertical cross section along the longitudinal direction of the tubular molded body, wherein the resin content of the other prepreg (P2) is higher than the previous prepreg (P2). P1)
And 1.1 to 1.4 times the same thickness.

In the present invention, the prepreg (P1), which is wound one or more times, as a prepreg constituting a layer in which the fibers are oriented in the longitudinal direction, and the prepreg (P1) substantially at the end edge of the winding. Is wound with another prepreg (P2) having fibers oriented in the same direction, with the winding start edges of the other prepreg (P2) facing each other. Further, the winding start edge of the prepreg (P1) and the other prepreg
The winding end edge of (P2) is wound so as to be substantially arranged on the same vertical cross section along the longitudinal direction of the tubular molded body.

Since the above-mentioned prepreg (P1) is continuously wound one or more turns, a slight gap is formed particularly at a portion where the prepreg on the second turn rides on the winding start edge of the first turn, and a step is also generated. . Here, in the present invention, as described above, the winding start edge position of the preceding prepreg (P1) and the winding end edge position of the other prepreg (P2) substantially match, that is, By arranging the winding start edge position of the preceding prepreg (P1) and the winding end edge position of the other prepreg (P2) so as to be on the same phase in the winding direction, immediately above the gap The other prepreg (P2) having the same fiber orientation exists at the position.

The other prepreg (P2) located just above the gap has a thickness substantially equal to that of the preceding prepreg and has a higher resin content than that of the preceding prepreg (P1). Therefore, the other prepreg (P2) has a high fluidity of the resin and fiber at the time of heat curing, and when molded in a state of being squeezed from the outside, the resin of the other prepreg (P2) having a high resin content and The fibers flow smoothly, the gaps are filled with a sufficient amount of resin and fibers, and the step at the switching portion is canceled out to have a uniform wall thickness and a smooth surface. At this time, two overlapping prepregs (P
In (1, P2), the orientation directions of the fibers are the same, and the fibers are parallel to each other. Therefore, both are easily adapted to each other on the same peripheral surface and are easily integrated.

Further, even if the above-mentioned prepreg (P1) is a prepreg having a small resin content, a plurality of turns of the single prepreg (P1) are continuously wound, and each prepreg (P1) is conventionally wound. Since a polymerized portion and a relatively large gap are not intentionally formed in each case, there is little need to actively flow the resin or fiber in a portion other than the portion where the gap is formed, and the uniform fiber density Is not impaired during molding. As a result, the density of the reinforcing fibers becomes constant in the circumferential direction,
The obtained molded body also has uniform bending rigidity in the circumferential direction.

The invention according to claim 5 of the present invention is characterized in that the other prepreg (P2) is wound with a length of 30 to 50 times its thickness. By winding at such a length,
A sufficient amount of resin for the flow can be secured, and the density distribution of the reinforcing fibers can be maintained substantially uniform.

The invention according to claim 6 is that the prepreg (P1) and the other prepreg (P2) have a TM ratio (P1) / (P2) of the reinforcing fibers constituting each of the prepregs of 0. 0.5-1
It is characterized by being.

[0025]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a sectional view of a tubular molded body according to a preferred embodiment of the present invention.

The tubular molded body 1 is composed of three layers 2, 3 and 4 in which the orientation directions of the reinforcing fibers are different. In the innermost layer 2 and the outermost layer 4, reinforcing fibers are oriented in the circumferential direction (90 ° direction) of the molded article 1, and in the intermediate layer 3, the reinforcing fibers are reinforced in the length direction (0 ° direction) of the molded article 1. The fibers F are oriented. The innermost layer 2 and the outermost layer 4 are thin,
Is formed to be at least twice as thick as the innermost layer 2 and the outermost layer 4.

FIG. 2 is a cross-sectional view showing a state of the tubular molded body 1 before molding, and FIG. 3 is an exploded explanatory view of the tubular molded body 1 before molding opened in a circumferential direction. To manufacture the molded body 1, first, a mandrel 10 having the same outer peripheral shape as the inner peripheral surface shape of the tubular molded body 1 is prepared.

The innermost layer 2 and the outermost layer 4 are each 1
It is composed of a plurality of prepregs 2a and 4a. The prepregs 2a and 4a are, for example, when the molded body 1 is a cylindrical body having the same diameter over its length direction,
The length in the direction orthogonal to the fiber extending direction is the tubular molded body 1
And the length in the fiber extending direction is cut into a rectangular shape having a circumferential dimension of the tubular molded body 1.

The intermediate layer 3 is composed of two prepregs 3a and 3b. 2 pieces of the prepreg 3
a, 3b, the length of the prepreg 3a in the fiber extending direction is the length dimension of the tubular molded body 1, and the length in the direction orthogonal to the fiber extending direction is the length of the tubular molded body 1. Is cut into a rectangular shape slightly smaller than twice the circumferential size of The length of the other prepreg 3b in the fiber extending direction is the length of the tubular molded body 1, and the length in the direction perpendicular to the fiber extending direction is approximately 30 to 30 times the thickness of the prepreg 3b.
It is cut into a rectangular shape 50 times as long. When these two prepregs 3a and 3b are connected by abutting their edges in the fiber extending direction, the dimension in the direction perpendicular to the fiber extending direction is twice the circumferential dimension of the tubular molded body 1. Length. Therefore, when the short prepreg 3b is wound after the long prepreg 3a, the winding end edge of the short prepreg 3b is on the same diameter as the winding start edge of the long prepreg 3a.

In the present invention, it is important that the other short prepreg 3b has a resin content of 1.1 to 1.4 times that of the long prepreg 3a. Further, it is preferable that the reinforcing fibers used for both the prepregs 3a and 3b have the same quality and the same dimensions.

When the molded body 1 is a tapered cylindrical body whose diameter gradually increases in the length direction, the prepreg 2a of the innermost layer 2 has an upper base having a peripheral dimension of a short diameter end, a lower dimension having a lower diameter, and a lower dimension. The base is cut into a trapezoidal shape having a circumferential dimension at the major end and a height equal to the length of the tubular body. The shape of the prepregs 3a and 3b of the intermediate layer 3 when the two 3a and 3b are connected to each other is such that the upper base is a plurality of times the outer diameter of the innermost layer 2 on the shorter diameter side, and the lower bottom is the innermost layer 2 on the longer diameter side. Is cut out into a trapezoidal shape having a multiple of the outer peripheral dimension of and a height equal to the length of the tubular body. Further, the prepreg 4a of the outermost layer 4 is cut into a trapezoidal shape in which the upper bottom is the outer peripheral dimension of the intermediate layer 3, the lower bottom is the outer peripheral dimension of the intermediate layer 3 on the longer diameter side, and the height is the length dimension of the tubular body. .

Of the four prepregs 2a, 3a, 3b, 4a cut into the above-described shape, first, the prepreg 2a constituting the innermost layer 2 is moved to the orientation direction of the reinforcing fibers of the prepreg 2a around the mandrel 10. Direction, that is, one turn in the direction of 90 °.

Next, the prepreg 3 constituting the intermediate layer 3
A long prepreg 3a is wound around the outer periphery of the prepreg 2a in the direction of 90 ° with the orientation direction of the reinforcing fiber oriented in the longitudinal direction of the mandrel 10, that is, in the direction of 0 °. . Subsequently, the short prepreg 3b having a high resin content is wound with its winding start edge abutting on the winding end edge of the prepreg 3a.

Finally, the prepreg 4a constituting the outermost layer 4 is wound once around the reinforcing fiber in a direction of 90 °. Further, after wrapping the PP tape around the outside, the wound body is heated to cure the resin of the prepreg. Thereafter, molding and demolding and removal of the PP tape are performed by a conventional method, and a cylindrical molded body is obtained. In addition, post-processing such as polishing and painting is performed according to the use of the molded article.

In the present invention, as described above, the winding start edge of the short prepreg 3b having a large resin content is attached to the winding end edge of the long prepreg 3a as the prepreg of the intermediate layer. Connected in state. The long prepreg 3a is continuously wound a plurality of times, and at this time, a gap 5 is slightly generated particularly at a switching portion where the second prepreg 3a rides on the winding start edge of the first turn. Also occurs.

However, in the present invention, as described above, the winding end edge 3a of the long prepreg 3a
Trimmed prepreg 3 having a high resin content as described above
b, so that the winding end edge of the prepreg 3b is on the same diameter as the winding start edge of the prepreg 3a. Therefore, when the prepreg 4a of the outermost layer 4 and the PP tape are molded while being pressed from the outside as described above, the prepreg 3b having a particularly high resin content exists in the portion where the gap is formed. As a result, the flow of the resin and the fiber is made smooth, the gap is filled with a sufficient amount of the resin and the fiber, the step at the switching portion is canceled out, the thickness becomes uniform, and the surface becomes smooth. Also, at this time, the prepregs 3a and 3b which overlap each other have the same fiber orientation direction and the fibers are parallel to each other.

Further, even if the prepreg 3a is a prepreg having a small resin content, a single prepreg 3a is continuously wound around a plurality of turns, so that the overlapped portion or the comparative portion is formed for each turn as in the prior art. Since the target gap is not intentionally formed, the portion other than the portion where the gap is formed is less required to actively flow the resin or fiber,
The uniform fiber density is not impaired during molding.
Therefore, the obtained molded body has uniform bending rigidity in the circumferential direction.

Hereinafter, the present invention will be described in more detail with reference to specific examples and comparative examples. In the examples and comparative examples, the following conditions were the same. <Mandrel> 10m in diameter with the same diameter in the length direction
m straight mandrel <Pre-preg winding pattern> Inner layer: Reinforcement fiber makes one turn in 90 ° direction Middle layer: Reinforcement fiber makes two turns in 0 ° direction Outermost layer: Reinforcement fiber makes one turn in 90 ° direction

<Prepreg in 90 ° direction (innermost layer, outermost layer)> Innermost layer (prepreg 2a) Carbon fiber prepreg “HRX330E032” manufactured by Mitsubishi Rayon Co., Ltd.
S "Carbon fiber: HR40 (fineness 0.1 g / m, elastic modulus 40 t)
/ Smm) Carbon fiber weight: 32 g / m ² Resin: # 330 Resin content: 30% Thickness: 0.029 mm Dimension in fiber extension direction 32 mm × dimension in fiber orthogonal direction 70
0 mm 2. Outermost layer (prepreg 4a) Carbon fiber prepreg “HRX330E032” manufactured by Mitsubishi Rayon Co., Ltd.
S "Carbon fiber: HR40 (fineness 0.1 g / m, elastic modulus 40 t)
/ Smm) Carbon fiber weight: 32 g / m ² Resin: # 330 Resin content: 30% Thickness: 0.029 mm 36 mm in the fiber extending direction × 70 in the fiber orthogonal direction
0mm

<Molding method> The prepregs 2a, 3a,
From above, 3b and 4a were sequentially wound, and a PP tape having a width of 10 mm was wound at a pitch of 5 mm and cured at 150 ° C. for 2 hours. Thereafter, the PP tape was molded and removed from the mold by a conventional method. Cut each 25mm on both ends and reduce the molded body length to 65mm
0 mm.

<Quality Evaluation> Confirmation of Flex The tubular molded body was divided into 10 ° in the circumferential direction, and the difference in flex in each direction was measured. 2. Measurement of Thickness Distribution Thickness unevenness on the wall of the tubular molded body was measured with a caliper. 3. Degree of unevenness In addition to the visual confirmation, the quality was confirmed by coating the molded body, and then checking the presence or absence of coating unevenness.

Example 1 The following prepreg was used in the direction of 0 ° (intermediate layer). Prepreg 3a: Carbon ray fiber prepreg “HSX350B160S” manufactured by Mitsubishi Rayon Co., Ltd. Carbon fiber: HS40 (fineness: 0.43 g / m, elastic modulus: 46 t / smm) Carbon fiber weight: 150 g / m ² Resin: # 350 Resin content: 20% Thickness: 0.111 mm 700 mm in the fiber extending direction x 65 mm in the direction perpendicular to the fiber Prepreg 3b: Carbon fiber prepreg “HSX350C150S” manufactured by Mitsubishi Rayon Co., Ltd. Carbon fiber: HS40 (fineness 0.43 g / m, elasticity) Rate 46 t / smm) Carbon fiber weight: 139 g / m ² Resin: # 350 Resin content: 25% Thickness: 0.113 mm Dimension 700 mm in the fiber extending direction × 5 mm in the direction perpendicular to the fiber

"Example 2" As the prepreg in the direction of 0 ° (intermediate layer), the carbon fiber of the above example was converted from HS40 to H40.
The same thing as the above-mentioned Example 1 was used except having changed to R40.

Example 3 Among the prepregs in the direction of 0 ° (intermediate layer), the prepreg 3 having a large resin content and being short was used.
The prepreg 3b had a resin content of 30%, and the carbon fiber weight was adjusted so that the thickness of the prepreg 3b was 0.113 mm.

[Comparative Example] A prepreg identical to the long prepreg 3a of Example 1 as a prepreg in the direction of 0 ° (intermediate layer) was cut into a size of 700 mm in a fiber extending direction × 70 mm in a direction perpendicular to a fiber. Use one that you did,
A molded article was produced without using the short prepreg 3b having a large resin content.

[Results] The tubular molded bodies of Examples 1 to 3 were checked for irregularities by touching their surfaces with their hands. As a result, no irregularities could be detected. However, in the tubular molded bodies of the comparative examples, the prepreg of the intermediate layer was used. The end of the roll was clearly perceived.

Further, the distribution of the bending stiffness in the circumferential direction was examined by folding each tubular molded body by hand.
Although the difference in the bending stiffness was hardly understood, it was found that the comparative example had a direction in which the bending stiffness was high.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a tubular molded body according to a preferred embodiment of the present invention.

FIG. 2 is a sectional view of the tubular molded body of FIG. 1 before molding.

FIG. 3 is an exploded explanatory view of the tubular molded body before molding of FIG. 2 opened in a circumferential direction.

[Explanation of symbols]

 Reference Signs List 1 tubular molded body 2 innermost layer 2a prepreg 3 intermediate layer 3a prepreg (long) 3b prepreg (short and large in resin content) 4 outermost layer 4a prepreg 5 gap 10 mandrel F reinforcing fiber

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) B29L 23:00 B29C 67/14 C 31:52 A01K 87/00 630A

Claims (6)

[Claims] 1. A tubular molded article made of a fiber-reinforced composite material, wherein the distribution of the density and bending rigidity of the reinforcing fibers in the circumferential direction is substantially uniform. 2. A golf club shaft comprising the tubular molded body according to claim 1. 3. A rod body comprising the tubular molded body according to claim 1. 4. A method for producing a tubular molded body, comprising: winding a prepreg on a mandrel in a plurality of layers at a required fiber angle and then curing the prepreg, wherein fibers are oriented in a longitudinal direction of the tubular molded body. The winding start edge of another prepreg (P2) in which the fibers were oriented in substantially the same direction as the prepreg (P1) was abutted against the winding end edge of the prepreg (P1) wound one or more times. Arranged in a state, and the winding start edge of the preceding prepreg (P1) and the winding end edge of the other prepreg (P2) on the same longitudinal section along the longitudinal direction of the tubular molded body. The other prepreg (P2) has a resin content of 1.1 to 1.4 times that of the previous prepreg (P1) and has the same thickness. A method for producing a tubular molded article, which is characterized in that: 5. The other prepreg (P2) has a thickness of 3%.
5. Winding at a length of 0 to 50 times.
A method for producing the tubular molded body according to the above. 6. The prepreg (P1) and the other prepreg (P2) have a ratio (P1) / (P2) of the tensile modulus TM of the reinforcing fiber constituting each of the prepregs of 0.5 to 1. The method for producing a tubular molded article according to claim 5 or 6, wherein