JP2019171676A - Fiber-reinforced resin tubular body, and method for manufacturing the same - Google Patents

Abstract

An object of the present invention is to provide a fiber-reinforced resin tubular body that includes a braid as a constituent body, has a good surface appearance, and does not require a polishing step, and a method of manufacturing the same. An innermost layer is a 0 ° fiber reinforced resin layer formed by six or more reinforcing fiber bundles having an orientation angle of 0 ° with respect to a longitudinal axis of a tubular body, and an outer layer is formed of the 0 ° fiber reinforced resin layer. At least one braided fiber reinforced resin layer in which a reinforcing fiber bundle is braided at a braid angle θ of 20 to 50 ° with respect to the longitudinal axis, and a fiber volume content of the 0 ° fiber reinforced resin layer (Vf ) Is 30% or more, the entire fiber volume content (Vtf) of the tubular body is 50 to 70%, and the tubular body satisfies the following conditions. <Conditions> In a cross section orthogonal to the longitudinal direction of the tubular body, the sum の 長 Dl (mm) of the major diameters Dl (mm) of the single yarn cross sections of the braided fiber reinforced resin layer in the outermost layer, and the outer peripheral length L (mm) of the tubular body And R (ΣDl / L) is 12 to 41. [Selection diagram] None

Description

  The present invention relates to a fiber-reinforced resin tubular body and a method for producing the same.

Fiber reinforced resin composite material (FRP), which is a composite of high-strength reinforcing fiber and curable resin material, is used for golf shafts, fishing rods, and sports bicycle parts that require light weight, high strength, and high rigidity. Has been. In particular, when a reduction in weight is required, it is advantageous to use a hollow fiber-reinforced resin tubular body.
As a method for manufacturing a golf shaft, Patent Document 1 includes a filament winding method in which one or a plurality of fiber reinforced resin layers are provided and a fiber bundle is wound while applying a predetermined tension to the fiber reinforced resin layer. A method has been proposed. As a specifically proposed method, a filament winding method dry method has been proposed, and a tow prepreg (also referred to as a tow prepreg, a yarn prepreg, or a strand prepreg) that is a fiber bundle impregnated with a resin composition in advance. Is used. In general, a multifilament winding method is adopted in which the tow prepreg is attached to a filament winding apparatus while being wound around a bobbin, and a plurality of tow prepregs are simultaneously supplied from each bobbin. However, in the manufacturing method described in Patent Document 1, since the golf shaft has an inclined structure in which the cross-sectional diameter is changed in the longitudinal direction, so-called batch production must be performed in units of the length of the golf shaft. It is not suitable as a method for continuously producing a long fiber-reinforced resin tubular body.
In addition, since a tow prepreg is used, there is an economic demerit that the cost of the reinforcing fiber is increased.

In the fiber reinforced resin structure, in order to more efficiently express the reinforcing effect of the reinforcing fiber, it has been studied to apply a reinforcing fiber having a braided structure.
Patent Document 2 proposes a method of manufacturing a fiber reinforced plastic that employs a braided structure as a core material. The manufacturing method is a method for manufacturing a fiber reinforced plastic in which a braid structure fed by a feed roller of a braid machine is fed into a pull-out molding machine and is taken up by a take-up roller having a slightly lower peripheral speed than the feed roller. However, this method eliminates the trouble of transporting the braided structure from the braided machine to the pull-out molding machine as in the prior art, and is free from the complexity of dimensional control of the braided structure. The method is not described.

On the other hand, after impregnating a resin into a braid composed around a mandrel composed of a soft tube expanded by compressed air, the tubular body is molded and cured into a predetermined cross-sectional shape on the mandrel, and then molded and cured A tubular body continuous molding system and method characterized by cutting the substrate have been proposed (for example, Patent Document 3 and Patent Document 4).
The tubular body continuous molding system described in Patent Document 3 can solve the disadvantages of a conventional system for molding a tubular body by impregnating a tubular braid with resin. That is, in the past, since the braider (braiding machine) and the resin impregnation process are not connected as an integrated continuous molding system, the composition braid is once removed from the braider, and then the resin impregnation process in the next process, etc. Configured to send. Therefore, the present invention provides a tubular body continuous molding system that can solve the problem that it is difficult to mold a tubular body of uniform quality because the productivity is poor and it is not a consistent continuous molding system. However, in this system, the cutting port of the tubular body is pressed by the pressure contact plate so that the supply of compressed air from the cutting moving vehicle to the soft tube is not interrupted by cutting the soft tube at the time of cutting, and from the discharge port of the pressure contact plate. The compressed air is blown out, and instead of the compressed air supplied to the soft tube constituting the mandrel from the cutting moving vehicle, the compressed tube is supplied to keep the soft tube inflated. Therefore, the apparatus becomes extremely complicated.

  Moreover, the continuous molding method of the tubular body of Patent Document 4 is a tubular body continuous molding method in which a braid composed in a cylindrical shape is continuously molded into various cross-sectional shapes. However, in this tubular body continuous molding method, since the mandrel expands the soft tube with compressed air, when the molded and hardened tubular body is cut, the compressed air leaks from the cut surface, and the mandrel changes in shape to the mandrel. Therefore, it is necessary to provide a compressed air chamber that covers the cut portion of the tubular body, and there is a problem that the manufacturing apparatus is complicated and expensive.

Thus, when trying to use braid for a fiber reinforced resin tubular body, conventionally, since a prepreg as a braid (braid) layer is used, the cost becomes high, and surface unevenness due to the braid layer is caused. Therefore, a polishing step is required for smoothing the surface, which causes problems of production loss and strength reduction.
Moreover, in the conventional continuous manufacturing method of a fiber reinforced resin tubular body mainly composed of braids, in order to maintain the mandrel in a predetermined size and shape, the equipment becomes complicated and the equipment cost increases.

International Publication No. 2016/185889 JP-A-4-108145 Japanese Patent Laid-Open No. 7-9596 JP 7-40449 A

  Then, the present inventors diligently studied for the purpose of providing a fiber-reinforced resin tubular body including a braid as a constituent body, having a good surface appearance and not requiring a polishing step, and a manufacturing method thereof. As a result, a fiber reinforced resin tubular body having an inner layer and an outer layer made of a fiber reinforced resin layer, the innermost layer being formed by six or more reinforcing fiber bundles having an orientation angle of 0 ° with respect to the longitudinal axis of the tubular body. At least one braided fiber having a 0 ° fiber reinforced resin layer and an outer layer braided on the outer circumference of the 0 ° fiber reinforced resin layer at a braid angle θ of 20 to 50 ° with respect to the longitudinal axis. A fiber volume content (Vf) of the 0 ° fiber reinforced resin layer is 30% or more, a fiber volume content (Vtf) of the entire tubular body is 50 to 70%, and The present inventors have found that the above-mentioned problems can be solved by using a fiber reinforced resin tubular body that satisfies a specific condition, and have completed the present invention.

That is, the present invention provides the following inventions [1] to [7].
[1] A fiber reinforced resin tubular body having an inner layer and an outer layer made of a fiber reinforced resin layer, wherein the innermost layer is formed by six or more reinforcing fiber bundles having an orientation angle of 0 ° with respect to the longitudinal axis of the tubular body. 0 ° fiber reinforced resin layer,
An outer layer is at least one braided fiber reinforced resin layer in which a reinforcing fiber bundle is braided at a set angle θ of 20 to 50 ° with respect to the longitudinal axis on the outer periphery of the 0 ° fiber reinforced resin layer;
The fiber volume content (Vf) of the 0 ° fiber reinforced resin layer is 30% or more,
A fiber-reinforced resin tubular body, wherein the entire fiber volume content (Vtf) of the tubular body is 50 to 70% and satisfies the following conditions.
<Conditions>
In the cross section orthogonal to the longitudinal direction of the tubular body, the sum ΣD _l (mm) of the long diameter D _l (mm) of the single yarn section of the braided fiber reinforced resin layer in the outermost layer, and the outer peripheral length L (mm) of the tubular body The ratio R (ΣD ₁ / L) of the above is 12 to 41.
ΣD _l (mm) = {single yarn diameter (μm) / cos θ} × (number of fibers per bundle) × (number of fibers) / 1000
(However, _Dl is the long diameter of the single yarn cross section of the braid fiber reinforced resin layer, and θ is the braid angle.)
[2] The innermost layer includes six or more reinforcing fiber bundles having an orientation angle of 0 ° with respect to the longitudinal axis of the tubular body, and includes an auxiliary braid obtained by braiding auxiliary yarns on the outer periphery of the reinforcing fiber bundle. ] The fiber reinforced resin tubular body described in the above.
[3] A method for producing a fiber-reinforced resin tubular body formed by impregnating and curing a plurality of fiber layers having different orientation angles of reinforcing fibers with respect to the longitudinal axis,
The manufacturing method of the fiber reinforced resin tubular body characterized by performing the following (1)-(7) processes sequentially.
(1) a step of inserting a mandrel having a shape corresponding to an inner diameter of a desired fiber-reinforced resin tubular body into the center of a tubular body manufacturing apparatus including a braid forming mechanism;
(2) A step of covering the outer periphery of the mandrel using 6 or more reinforcing fiber bundles and forming a 0 ° fiber layer;
(3) A required number of reinforcing fiber bundles are arranged in a tubular body manufacturing apparatus equipped with a braid forming mechanism, and the reinforcing fiber bundles are entangled at a predetermined set angle θ on the 0 ° fiber layer. i), forming at least one braid layer under (ii),
<Conditions>
(i) The tension applied to the reinforcing fiber bundle constituting the braid is 0.01 to 0.20 cN / dtex per fineness (dtex) of the fiber bundle, and the braiding angle θ is set to the left and right objects with respect to the longitudinal direction of the mandrel. Braid the braid as ± 20 ° to ± 50 °.
(ii) In an arbitrary cross section orthogonal to the longitudinal direction of the obtained tubular body, the sum ΣD _l (mm) of the major axis D _l (mm) of the single yarn section of the braided fiber reinforced resin layer in the outermost layer; The braided layer is formed so that the ratio R (ΣD ₁ / L) to the outer peripheral length L (mm) is 12 to 41.
ΣD _l (mm) = {single yarn diameter (μm) / cos θ} × (number of fibers per bundle) × (number of fibers) / 1000
(However, _Dl is the major axis of the single yarn cross section of the braid layer, and θ is the braid angle.)
(4) A step of impregnating the 0 ° fiber layer and the braided layer with a thermosetting resin composition having a viscosity of 150 mPa · s or less to obtain a linear product,
(5) a step of curing the thermosetting resin composition while molding by inserting a linear object into a mold having a hole shape corresponding to the outer shape of the desired fiber-reinforced resin tubular body;
(6) A step of cutting the cured linear product into a predetermined length, and (7) a step of removing the mandrel from the cut linear product to obtain a fiber-reinforced resin tubular body.
[4] In the step of forming the 0 ° fiber layer of (2) above, the auxiliary fiber entangles the reinforcing fiber bundle for the 0 ° fiber layer, and the ratio of the auxiliary yarn to the reinforcing fiber bundle of the 0 ° fiber layer is The method for producing a fiber-reinforced resin tubular body according to the above [3], wherein an auxiliary yarn braid having a fiber volume of 1 to 2 is formed.
[5] The braid layer forming process of (3) is performed in two successive steps, and at least the outermost braid layer is formed so that the ratio R (ΣD ₁ / L) satisfies 12 or more and 41 or less. [3] The method for producing a fiber-reinforced resin tubular body according to [4].
[6] The method for producing a fiber-reinforced resin tubular body according to any one of [3] to [5], wherein the reinforcing fiber bundle is a carbon fiber bundle.
[7] The fiber according to any one of [3] to [6], wherein in the mandrel insertion step of (1), a long thermoplastic hollow tubular body or rod-shaped body is used as a mandrel. A method for producing a reinforced resin tubular body.

  According to the present invention, it is possible to provide a fiber reinforced resin tubular body including a braid as a constituent body, having high bending physical properties and the like, having a good surface appearance and not requiring a polishing step, and a method for producing the same.

It is a partially broken perspective view which shows the layer structure of the fiber reinforced resin tubular body of this invention. In the fiber reinforced resin tubular body of the present invention, each of the reinforcing fiber bundles constituting the 0 ° fiber reinforced resin layer and the braided fiber reinforced resin layer is an explanatory diagram of a set angle θ with respect to the longitudinal direction of the fiber reinforced resin tubular body. FIG. 3 is a conceptual explanatory diagram of a sum ΣD _l of a major axis D _l (mm) of a single yarn cross section of a braided fiber reinforced resin layer in an outermost layer in a cross section orthogonal to a longitudinal direction (Y axis) of a fiber reinforced resin tubular body of the present invention. (A) A schematic diagram in which the single yarn F _b of the braided fiber reinforced resin layer shows an inclination angle θ with respect to the Y axis, (b) the long diameter D _l of the single yarn cross section is “single yarn diameter D _b (μm ) / cos [theta] diagram for explaining a relation that "an enlarged schematic explanatory view showing that single yarn F _b braid fiber-reinforced resin layer of the outermost layer exhibits an elliptical shape in cross section of (c) the tubular body is there. It is a schematic side view of the braid formation mechanism (braid making machine) used for manufacture of the fiber reinforced resin tubular body of the present invention. It is explanatory drawing of the running track of a braid for bobbins. It is a schematic diagram of the linear body by which the braid fiber layer was formed in the outer periphery of a 0 degree reinforcement fiber bundle. It is explanatory drawing of the one aspect | mode of the manufacturing method of the fiber reinforced resin tubular body of this invention. It is explanatory drawing of the other aspect of the manufacturing method of the fiber reinforced resin tubular body of this invention. The example of the orthogonal cross section of the longitudinal direction of the fiber reinforced resin tubular body of this invention is shown, (a) Round pipe, (b) It is explanatory drawing of a substantially circular pipe.

  Hereinafter, preferred embodiments of the present invention will be described. Each embodiment shown in the accompanying drawings shows an example of a typical embodiment according to the present invention, and does not limit the scope of the present invention.

The fiber reinforced resin tubular body of the present invention is a fiber reinforced resin tubular body having an inner layer and an outer layer made of a fiber reinforced resin layer, and the innermost layer is a reinforcing fiber having an orientation angle of 0 ° with respect to the longitudinal axis of the tubular body. It is a 0 ° fiber reinforced resin layer formed by 6 or more bundles, and the outer layer is braided on the outer periphery of the 0 ° fiber reinforced resin layer at a braid angle θ of 20 to 50 ° with respect to the longitudinal axis. At least one braided fiber reinforced resin layer, the fiber volume content (Vf) of the 0 ° fiber reinforced resin layer is 30% or more, and the total fiber volume content (Vtf) of the tubular body is 50. It is ˜70% and satisfies the following condition.
<Conditions>
In the cross section orthogonal to the longitudinal direction of the tubular body, the sum ΣD _l (mm) of the long diameter D _l (mm) of the single yarn section of the braided fiber reinforced resin layer in the outermost layer, and the outer peripheral length L (mm) of the tubular body The ratio R (ΣD ₁ / L) of the above is 12 to 41.
ΣD _l (mm) = {single yarn diameter (μm) / cos θ} × (number of fibers per bundle) × (number of fibers) / 1000
(However, _Dl is the long diameter of the single yarn cross section of the braid fiber reinforced resin layer, and θ is the braid angle.)

The fiber reinforced resin tubular body of the present invention will be described with reference to FIGS. FIG. 1 is a partially broken perspective view showing a layer structure of a fiber reinforced resin tubular body of the present invention, which is composed of an inner layer 1 and an outer layer 2. The innermost layer is a 0 ° fiber reinforced resin layer including 6 or more reinforcing fiber bundles 3 having an orientation angle of 0 ° with respect to the longitudinal axis of the tubular body and a fiber volume content (Vf) of 30% or more.
The fiber-reinforced resin tubular body of the present invention has an outer diameter of about 8 to 15 mm, an inner diameter of 6 to 13 mm, and a wall thickness of about 0.5 to 1 mm. It is difficult to arrange evenly in the reinforced resin layer, resulting in uneven fibers and increased uneven thickness.
In addition, the volume content (Vf) of the reinforcing fiber of the 0 ° fiber reinforced resin layer needs to be 30% or more in order to ensure the bending property in the longitudinal direction. The upper limit of the volume content (Vf) of the reinforcing fiber of the 0 ° fiber reinforced resin layer is more preferably 50% or less from the balance with the volume content of the reinforcing fiber of the braided fiber reinforced resin layer contributing to the improvement of the lateral pressure strength. preferable.
Furthermore, the cross-sectional shape of the 0 ° fiber is preferably a shape having a major axis and a minor axis, and in particular, the bending property can be improved by controlling the thickness variation of the 0 ° fiber and the meandering of the braid in the outer layer. The ratio of the major axis to the minor axis is preferably 5-10.

The outer layer is at least one braided fiber reinforced resin layer in which the reinforcing fiber bundle 4 is braided at the outer periphery of the 0 ° fiber reinforced resin layer at a braid angle θ of 20 to 50 ° with respect to the longitudinal axis. If a braided fiber reinforced resin layer is used as the innermost layer and a 0 ° fiber reinforced resin layer is provided on the outer periphery, the 0 ° reinforcing fiber bundle meanders and the bending properties deteriorate, reflecting the stitches of the braided layer. The resin layer must be disposed on the outer periphery of the 0 ° fiber reinforced resin layer. Further, the arrangement of the 0 ° fiber reinforced resin layer as the innermost layer contributes to stabilization of the mandrel removal process. When the number of braided fiber reinforced resin layers is 3 or more, the production stability such as avoiding unevenness of fibers in the cross section in the longitudinal direction and clogging of the mold in the manufacturing process, surface appearance, and external accuracy From the standpoint of securing, etc., it is preferably composed of one layer or two layers.
Furthermore, the cross-sectional shape of the reinforcing fiber bundle is preferably a shape having a major axis and a minor axis, since the smoothness and mechanical properties in the outermost layer of the fiber-reinforced resin tubular body can be improved by controlling the meandering at the stitches. In particular, the ratio of the major axis to the minor axis is preferably 20-50. In addition, if the ratio of the major axis to the minor axis exceeds 50, a separate fiber opening process is required, and the apparatus becomes complicated.
FIG. 2 shows the relationship between the 0 ° reinforcing fiber bundle 31, the braid reinforcing fiber bundles 41 and 42, and the braiding angle θ. The 0 ° reinforcing fiber bundle 31 is arranged at an orientation angle of 0 ° (parallel) with respect to the longitudinal axis Y of the fiber reinforced resin tubular body, and the braid reinforcing fiber bundle 41 is + θ with respect to the longitudinal axis Y. Thus, the braid reinforcing fiber bundle 42 is formed into a fiber reinforced resin layer after being braided by a braid making machine so as to form −θ.
The braided fiber reinforced resin layer disposed on the outer periphery of the 0 ° fiber reinforced resin layer is configured by braiding a reinforcing fiber bundle at a braid angle θ of 20 to 50 ° with respect to the longitudinal axis. When the braid angle θ is less than 20 °, it does not contribute to the improvement of the lateral pressure strength of the tubular body by the combination with the 0 ° fiber reinforced resin layer, and when it exceeds 50 °, the meandering of the fiber bundle at the stitches of the braid increases and the fiber direction Will vary and reduce the contribution to lateral pressure. That is, the ratio of the fiber bundle in the width direction of the pipe that contributes to the lateral pressure by meandering decreases, and the ratio that contributes to the thickness (Z-direction axis) direction increases. The thickness direction hardly contributes to the physical properties of the pipe.

  The total fiber volume content (Vtf) of the tubular body is 50 to 70%. When Vtf is less than 50%, the absolute amount of reinforcing fibers contributing to physical property reinforcement is small and the physical properties are low, and in addition, unevenness is likely to occur on the surface due to curing shrinkage of the resin. On the other hand, if Vtf exceeds 70%, the pulling resistance of the mold becomes excessive during production, and stable production becomes difficult.

(R (ΣD _l / L) between the sum ΣD _l (mm) of the long diameter D _l (mm) of the single yarn cross section and the outer peripheral length L (mm) of the tubular body)
Further, the fiber reinforced resin tubular body of the present invention has a sum ΣD _l (mm) of the major axis D _l (mm) of the single yarn section of the braided fiber reinforced resin layer in the outermost layer in the cross section perpendicular to the longitudinal direction of the tubular body. It is necessary to satisfy the condition that the ratio R (ΣD ₁ / L) to the outer peripheral length L (mm) of the tubular body is 12 to 41.
The ratio R will be described with reference to FIG. FIG. 3A shows a state in which the single yarn (filament) Fb of the reinforcing fiber in the outermost layer of the braided fiber reinforced resin layer is oriented at a set angle θ with respect to the longitudinal axis Y of the tubular body. Assuming that the cross section of the single yarn of the braided reinforcing fiber is circular and has a diameter _Db , as shown in FIG. 3B, in the single yarn cross section perpendicular to the longitudinal axis, F _b is inclined, so that the long diameter D _l The long diameter D _l (μm) of the single yarn cross section is in a relationship of “single yarn diameter D _b (μm) / cos θ”. FIG. 3C schematically shows that the single yarn cross section is elliptical in the cross section.
This ratio R (ΣD ₁ / L) is the number of times the sum of the long diameters of the single yarns in the outermost braided fiber reinforced resin layer is larger than the outer peripheral length of the tubular body as a product. Shows what is in minutes. Here, the sum ΣD _l (mm) of the major axis D _l (μm) of the single yarn cross section is obtained by the following equation.
ΣD _l (mm) = {single yarn diameter (μm) / cos θ} × (number of fibers per bundle) × (number of fibers) / 1000
If ΣD ₁ / L is less than 12, a gap is formed between the fiber bundles, and the surface roughness (appearance) of the fiber reinforced resin tubular body is inferior. If it exceeds 41, there is room for deformation when inserted into the mold. Therefore, the meandering at the stitches is increased and the surface roughness is reduced. ΣD ₁ / L is particularly preferably from 15 to 25 from the viewpoint of improving mechanical properties such as flexural modulus and surface smoothness.

  The fiber reinforced resin tubular body of the present invention is composed of six or more reinforcing fiber bundles whose innermost layer has an orientation angle of 0 ° with respect to the longitudinal axis of the tubular body, and an auxiliary yarn in which auxiliary yarns are braided on the outer periphery of the reinforcing fiber bundle. It can be set as the structure provided with a braid. Each reinforcing fiber bundle is entangled with an auxiliary yarn having a low fineness of about 1/20 to 1/50 of the fineness of the reinforcing fiber bundle, and the ratio of the auxiliary yarn to the reinforcing fiber bundle of the 0 ° fiber layer is 1-2 fibers. By forming the auxiliary yarn braid that is volume%, it is possible to prevent the 0 ° reinforcing fiber bundle from being disturbed, and to suppress the occurrence of voids between the fiber bundles and the deterioration of physical properties.

Subsequently, the manufacturing method of the fiber reinforced resin tubular body of this invention is demonstrated.
The method for producing a fiber reinforced resin tubular body of the present invention is a method for producing a fiber reinforced resin tubular body obtained by impregnating and curing a thermosetting resin composition in a plurality of fiber layers having different orientation angles of reinforcing fibers with respect to the longitudinal axis. In addition, the following steps (1) to (7) are sequentially performed. Hereinafter, it demonstrates in order of a process.

[(1) Step of inserting a mandrel through the center of a tubular body manufacturing apparatus including a braid forming mechanism]
This is a step of inserting a mandrel having a shape corresponding to the inner diameter of a desired fiber-reinforced resin tubular body into the center of a tubular body manufacturing apparatus having a braid forming mechanism.
In the process of curing the thermosetting resin composition, the mandrel has a shape corresponding to the inner diameter (hollow part) of the fiber-reinforced resin tubular body, has a smooth surface, and is inserted into a subsequent mold and molded. Tubular or rod-like materials made of thermoplastic resin or metal that do not exhibit behavior such as deformation or heat shrinkage can be used. The mandrel is preferably continuous from the viewpoint of continuously producing a fiber-reinforced resin tubular body, but if it can be supplied without interruption, a non-continuous (fixed) one is continuously supplied. May be. From the viewpoint of being able to supply continuously, a linear body in which the outer periphery of a continuous FRP linear object is coated with a thermoplastic resin, a hollow thermoplastic resin pipe, or a linear body is supplied while being continuously extruded. It is preferable. For example, a mandrel made of polypropylene resin may include a linear body such as a pipe having an outer diameter × inner diameter of 8.8 × 4.4 mm, a pipe of 6.6 × 2.6 mm, and a rod having an outer diameter of 4.3 mm. Can do.
The mandrel is guided to the central opening of a braid manufacturing apparatus to be described later.

[(2) Step of forming 0 ° fiber layer using reinforcing fiber bundle]
First, a braid forming mechanism (braid manufacturing apparatus) used in the present invention will be described with reference to FIG. The braid manufacturing apparatus 20 shown in FIG. 4 moves in the horizontal direction on the vertical disk 11 having the center opening 12, the plurality of bobbins 40 for supplying braid yarn for running on the disk 11, and the center line of the disk 11. A free mandrel (tubular body) M and a package (not shown) for supplying a 0 ° reinforcing fiber bundle 31 disposed on the side different from the composition point P with respect to the disk 11 are mainly configured. After the 0 ° reinforcing fiber bundle 31 is guided to the through hole of the guide 13, it is disposed on the outer periphery of the mandrel M in the vicinity of the braid forming point P.

[(3) Step of forming a braid layer on the 0 ° fiber layer]
The braid fiber layer for obtaining the fiber-reinforced resin tubular body of the present invention is entangled at a predetermined braid angle θ using the braid production apparatus 20 shown in FIG. 4 described above, and the following conditions (i) and (ii) At least one braid layer is formed below.
As shown in FIG. 5, for example, in a braided braid manufacturing apparatus, the braid manufacturing apparatus is a chain-shaped traveling track having an inner (S-twisted) track 16 a and an outer (Z-twisted) track 16 b on the disk 11. 16 is formed, and a plurality of bobbins 40 travel on the traveling track 16 in a clockwise direction (S twist) or counterclockwise (Z twist). As described above, the bobbin 40 travels in the reverse direction on the travel track 16 so that the braids 41 and 42 can be entangled on the mandrel M so as to rise rightward or leftward. The number of bobbins 40 traveling on the traveling track 16 is one or two with respect to one set of the inner track 16a and the outer track 16b.

(Condition (i) -1)
(i) The braid is braided with the tension applied to the reinforcing fiber bundle constituting the braid being 0.01 to 0.20 cN / dtex per fineness (dtex) of the fiber bundle. That is, in FIG. 4, 0.01 to 0.20 cN / per fiber bundle corresponding to the fineness dtex of the fiber bundles constituting the braided reinforcing fiber bundles 41 and 42 from the bobbin 40 set in the braid manufacturing apparatus 20 The tension of the braided reinforcing fiber bundles 41 and 42 is adjusted by a tension adjusting device (not shown) so as to be pulled out with the tension of dtex. Examples of the tension adjusting device include a spring and a weight set on a carrier.
If the tension of the reinforcing fiber bundle constituting the braid is less than 0.01 cN / dtex when braiding the braid, the braid layer is likely to be deformed and meandered by the force in the longitudinal axis (0 °) direction received from the molding die. , Leading to clogging in the mold and deterioration of physical properties. On the other hand, when the tension exceeds 0.20 cN / dtex, single yarn breakage due to friction with a guide or the like is likely to occur, and physical properties are deteriorated and defects such as fiber breakage in the mold are likely to occur.
The tension (cN) is a value obtained by multiplying the total fineness dtex per fiber bundle by “0.01 to 0.20 cN / dtex” in the braided reinforcing fiber bundle.

(Condition (i) -2)
In the method for manufacturing a fiber reinforced resin tubular body of the present invention, the braid angle θ of the braid layer is set to ± 20 ° to ± 50 ° for the left and right objects with respect to the longitudinal direction of the mandrel for the reason described above. Braid. The set angle θ is set by the line speed and the number of rotations of the bobbin on the track 16 (how many times the track 16 rotates per unit time).

(Condition (ii))
In an arbitrary cross section orthogonal to the longitudinal direction of the obtained tubular body, the sum ΣD _l (mm) of the long diameter D _l (mm) of the single yarn cross section of the braided fiber reinforced resin layer in the outermost layer, and the outer peripheral length L of the tubular body The braid layer is formed so that the ratio R (ΣD ₁ / L) to (mm) is 12 to 41.
ΣD _l (mm) = {single yarn diameter (μm) / cos θ} × (number of fibers per bundle) × (number of fibers) / 1000
(However, _Dl is the major axis of the single yarn cross section of the braid layer, and θ is the braid angle.)
As described above, as described above, when ΣD ₁ / L is less than 12, the surface roughness (appearance) of the fiber-reinforced resin tubular body is inferior, and when it exceeds 41, the surface roughness is deteriorated due to the unevenness of the stitches.
This condition can be satisfied by appropriately setting the single yarn diameter (μm) of the braided reinforcing fiber bundle, the number of the single yarns, the number of constituent fibers, the number of reinforcing fiber bundles of the braided layer, and the braiding angle θ.

[(4) Step of impregnating 0 ° fiber layer and braid layer with thermosetting resin composition]
The linear material in which the 0 ° fiber layer and the braid layer are sequentially formed on the mandrel M by the step (3) is led to the impregnation step shown in FIG. 7, and a thermosetting resin composition having a viscosity of 150 mPa · s or less is obtained. A linear material impregnated in each fiber layer is obtained. Specifically, the impregnation is carried out by running in an impregnation tank provided with a seal portion for preventing resin leakage on the entrance side and the exit side of the impregnation tank parallel to the traveling linear object. It is desirable that the impregnation tank or the thermosetting resin composition supply tank (both not shown) can be temperature-controlled to keep the viscosity constant.
The viscosity of the thermosetting resin composition is required to be 150 mPa · s or less from the viewpoint of ensuring good impregnation of each fiber layer. If it exceeds 150 mPa · s, a resin-impregnated portion is generated in the fiber-reinforced resin tubular body after curing, causing problems such as cavities and starting points of cracks, deterioration of mechanical properties, and poor surface appearance. Occurs.
The lower limit of the viscosity is preferably 50 mPa · s or more, and the upper limit is preferably 100 mPa · s or less.

[(5) Step of curing the thermosetting resin composition while forming a linear product]
The linear material obtained by impregnating each fiber layer with the thermosetting resin composition obtained in the step (4) is inserted into a mold (molding mold) having a hole shape corresponding to the outer shape of the desired fiber-reinforced resin tubular body. Then, it is led to a step of curing the thermosetting resin composition while performing pultrusion molding. As the mold, a so-called metal mold is used, and the mold is heated to a temperature corresponding to the curing temperature of the thermosetting resin composition, for example, 150 to 170 ° C. The length of the mold is approximately 50 to 200 mm, and the drawing speed is approximately 0.05 to 0.1 m / min, and a cured continuous linear object having a predetermined outer shape is obtained.

[(6) Step of cutting the cured linear object into a predetermined length]
This is a step of cutting the linear object obtained in the step (5) into a required predetermined length (fixed length), and a mandrel is included inside. For the cutting, a normal cutting device provided with a rotary blade or the like is used.

[(7) Step of removing the mandrel and obtaining a fiber reinforced resin tubular body]
The mandrel is a step of removing the mandrel from the regular mandrel-attached fiber reinforced resin tubular body obtained in the step (6), and the mandrel is usually not adhered to the 0 ° fiber reinforced resin layer on the outer periphery thereof. If the material is selected, the mandrel can be removed relatively easily, and a fiber-reinforced resin tubular body having a desired shape can be obtained.

In the method for producing a fiber-reinforced resin tubular body of the present invention, in the step of forming the 0 ° fiber layer of (2), the 0 ° fiber layer is entangled with the reinforcing fiber bundle for the 0 ° fiber layer by the auxiliary yarn. An auxiliary yarn braid in which the ratio of the auxiliary yarn to the reinforcing fiber bundle is 1 to 2 fiber volume% can be formed.
In order to form the auxiliary yarn braid on the reinforcing fiber bundle of the 0 ° fiber layer, as shown in FIG. 8, a braid manufacturing apparatus 100 for forming the auxiliary yarn braid at the time of forming the 0 ° fiber layer is prepared, and the auxiliary yarn The braid forming apparatus 100 is guided through a hole (not shown) provided at the center of the track so that the bobbin of the auxiliary yarn 311 is set and the 0 ° reinforcing fiber bundle is supplied to the center of the track. Placed on the mandrel. The auxiliary yarn 311 uses a yarn having a low fineness of about 1/20 to 1/50 of the fineness of the reinforcing fiber bundle, and is entangled with 0 ° fiber so that the ratio of the auxiliary yarn braid is 1 to 2 fiber volume%. Without affecting the physical properties of the fiber reinforced resin tubular body, it is possible to prevent disturbance of the 0 ° reinforcing fiber bundle and to prevent the physical properties from being lowered due to the generation of voids between the fiber bundles.

In the method for producing a fiber-reinforced resin tubular body of the present invention, the braided cord layer forming step (3) is performed in two successive steps, and at least the outermost braid cord layer has a ratio R (ΣD ₁ / L) of 12 or more. It can be formed to satisfy 41 or less.
In this case, as shown in FIG. 8, the braid layer is formed in two stages, the first layer and the second layer, and the ratio R (ΣD ₁ / L) of the outermost braid layer formed in the second layer. When the ratio is 12 or more and 41 or less, there is a disadvantage when the ratio increases beyond 41, for example, when the fiber bundle is thickened, there is a possibility that the step at the overlapping portion becomes large and the surface is roughened. In addition, by increasing the assembly angle, the possibility that the meandering increases and sufficient physical properties cannot be exhibited can be reduced.

The raw materials used for the fiber-reinforced resin tubular body of the present invention will be described below.
(Reinforcing fiber)
Reinforcing fibers constituting the fiber reinforced resin layer of the fiber reinforced resin tubular body include carbon fibers, glass fibers, various ceramic fibers such as Tyranno fibers, boron fibers, copper, stainless steel and other metal fibers, amorphous fibers, aromatic polyamides, Organic fibers such as aromatic polyesters (for example, aramid fibers, liquid crystal polyester (LCP) fibers), mixed fabrics thereof, and the like can be used. Among these, carbon fiber and glass fiber are preferable, and carbon fiber is particularly preferable.
Examples of the carbon fiber include PAN-based, pitch-based, and rayon-based carbon fibers. From the viewpoint of tensile strength, PAN-based carbon fibers are preferred. Examples of the form of carbon fiber include carbon fiber twisted yarn, untwisted yarn, and non-twisted yarn. From the viewpoint of handleability of the fiber bundle, non-twisted yarn is preferable. Moreover, the carbon fiber may contain graphite fiber.

(Thermosetting resin composition)
As described above, the reinforcing fiber (bundle) is impregnated with the thermosetting resin composition. Examples of the thermosetting resin that is the base resin of the resin composition include urethane acrylate resins, epoxy resins, phenol resins, vinyl ester resins, polyester resins, unsaturated polyester resins, and the like. Among these, urethane acrylate resins, vinyl ester resins, and unsaturated polyester resins are preferable in terms of handling, and in particular, urethane acrylate resins are compatible with workability such as shortening the curing time, productivity, and mechanical properties. From the viewpoint of being able to do so.

  The thermosetting resin composition used in the present invention can contain a thermal polymerization initiator (curing agent). Examples of the curing agent that can be used include medium temperature curable organic peroxides that can be cured at about 50 to 120 ° C., esters thereof, and organic azo compounds.

  The curing agent is preferably used in the range of 0.1 to 5 parts by mass with respect to 100 parts by mass of the thermosetting resin. If the curing agent is in the range of 0.1 to 5 parts by mass, the fiber-reinforced resin sheet will not be insufficiently cured and will not be too uneconomical.

  Furthermore, you may add the adhesive improvement agent, an oligomer, a monomer, a high molecular compound, an organic particle, an inorganic particle, etc. for improving adhesiveness with a reinforcement fiber to a thermosetting resin composition.

  EXAMPLES Hereinafter, although this invention is demonstrated by Examples 1-9 and Comparative Examples 1-7, this invention is not limited to these Examples.

<Mandrel production>
7 and 8, the mandrel shown as M at the right end of the drawing uses a melt extrusion apparatus equipped with a die having a predetermined inner diameter (not shown), and the outer periphery of the circular FRP linear material is made of polypropylene ( ) Prime Polymer Co., Ltd., Prime Polypro J-702LJ, MFR = 2.0), the outer diameter (coating outer diameter) × the inner diameter (FRP linear material outer diameter) is 8.8 mm × 4.5 mm, A mandrel composed of three types of polypropylene resin-coated linear bodies of 6.6 mm × 4.5 mm, 4.3 mm × 2.0 mm was tuned to the production speed during the production of the fiber reinforced resin tubular body of each example and comparative example. Then, it was continuously guided and supplied to the center hole of the disk of the braid manufacturing apparatus.

<Manufacture of 0 ° fiber layer>
(Reinforcing fiber bundle)
As the 0 ° reinforcing fiber bundle, carbon fiber manufactured by Toray Industries, Inc. having the following trade name was used as the PAN-based carbon fiber.
TORAYCA (registered trademark) 700SC-24000 (single yarn diameter 7 μm, number 24,000 (in Tables 1 and 2, “24K” is indicated, “1000” is similarly indicated as “K”), 1650 dtex)
Pyrofil (registered trademark) TR 30S 6L (filament diameter: 7 μm, number of 6000, 4000 dtex)
Pyrofil (registered trademark) TR 30S 12L (filament diameter: 7 μm, number 12,000, 8000 dtex)
(Auxiliary thread)
-Glass yarn manufactured by Nittobo Co., Ltd., ECE225 glass yarn (filament diameter: 7.4 μm, number: 200, 67.5 tex, number of twists: 1.0 / 25 mm)
(1) As a first aspect, the auxiliary yarn is used on the upstream side of the braid forming point P using the required number of carbon fibers of the above-mentioned product number as the reinforcing fiber bundles shown in Tables 1 and 2 around the mandrel M having a predetermined diameter. And led to the braid layer forming step shown in FIG.
(2) As a 2nd aspect, it is 0 degrees which has the auxiliary braid layer by the said glass yarn by the braid manufacturing apparatus 100 shown in FIG. A fiber layer was formed and led to a (main body) braid layer forming step.

<Formation process of braid layer>
A braided reinforcing fiber bundle made of the following carbon fibers is set in the braid manufacturing apparatuses 20 and 21 shown in FIGS. 7 and 8, and fiber tension: 0.03 to 0.09 cN / dtex, braid angle θ As shown in Fig. 2, a wire having a first layer, or a first and second braided fiber layer on the outer periphery of the 0 ° fiber layer in a range of ± 20 ° to ± 50 ° with respect to the longitudinal axis. A product was formed.
(Braid reinforced fiber bundle)
PAN-based carbon fiber / Pyrofil (registered trademark) TR 30S 3L manufactured by Mitsubishi Chemical Corporation (filament diameter: 7 μm, number of 3000, 2000 dtex)
Pyrofil (registered trademark) TR 30S 6L (filament diameter: 7 μm, number of 6000, 4000 dtex)
Pyrofil (registered trademark) TR 30S 12L (filament diameter: 7 μm, number 12,000, 8000 dtex)

<Impregnation step of thermosetting resin composition>
The said linear thing in which the braided fiber layer was formed was made to run in the impregnation tank in which the following thermosetting resin composition was inject | poured, and the linear thing which the resin composition impregnated was obtained.
(Thermosetting resin composition)
The main component of thermosetting resin is urethane acrylate (manufactured by Nippon Iupika Co., Ltd., product name: CBZ 500LM-AS) 100 parts by mass, and the main curing agent is benzoyl peroxide (manufactured by Nippon Oil & Fats Co., Ltd., product name: Nyper ( (Registered trademark) FF) 4 parts by mass, organic peroxide as a secondary curing agent (manufactured by NOF Corporation, product name: Percure (registered trademark) HI), 1 part by mass, additive for viscosity adjustment As a thermoplastic resin composition, 10 parts by mass of a styrene monomer and 0.2 parts by mass of an additive for carbon fiber reinforced resin (CFRP) (product name: PR-CBZ 02) manufactured by Nippon Upica Co., Ltd. did.
In the examples, the viscosity of the resin composition is varied in the range of 58 to 145 mPa · s as shown in Table 1, and in the comparative example in the range of 68 to 217 mPa · s as shown in Table 2. The linear material was led to the next step.
The viscosity of the thermosetting resin composition was measured at a liquid temperature of 20 ° C. using a rotary viscometer (manufactured by A & D, model Viscometer SV-10).

<Step of curing the thermosetting resin composition while molding through a mold>
As a process of curing the thermosetting resin composition while being inserted through the mold of the present invention, the cross-sectional shape is a round pipe shape shown in FIG. 10 (a), and the top and bottom shown in FIG. 10 (b). Two types of fiber reinforced resin tubular bodies were obtained although the cross-sectional shape was shown as “substantially circular pipes” in Tables 1 and 2. The mold for forming the round pipe was made of stainless steel, provided with an extraction hole having an inner diameter of 10 mm and 10.3 mm, a length in the extraction direction of 120 mm, and the mold temperature was controlled at 150 to 170 ° C.
On the other hand, the die for forming a substantially circular pipe is also provided with a drawing hole having an outer shape of an arc of 8.2 mm / parallel portion of 7.6 mm, or an arc of 6.0 mm / parallel portion of 5.4 mm. The length was 120 mm, and the mold temperature was controlled as described above.
The drawing speed was changed in the range of 0.05 to 0.10 m / min corresponding to each example and comparative example.

<Cut process>
After curing, after passing through a take-up machine, it was cut to a predetermined length using a rotating round blade cutter.

<Mandrel extraction process>
After cutting, the mandrel was pulled out to obtain a fiber reinforced resin tubular body.

About the obtained fiber reinforced resin tubular body, it measured and evaluated with the following method.
<Evaluation method of fiber reinforced resin tubular body>
(Fiber volume content)
The fiber volume content, Vf, and Vtf were calculated by the combustion method with reference to JIS K 7075: 1991. The test piece was calculated by cutting a fiber reinforced resin tubular body every 10 mm. (N = 5)
(Measurement method of outer diameter, inner diameter, thickness)
The outer diameter and inner diameter were measured by sandwiching each test piece with a caliper, and the average value of 5 points (n = 5) was obtained. The thickness was calculated by (outer diameter) − (inner diameter).
(Measurement method of uneven thickness)
The uneven thickness was calculated from (maximum thickness)-(minimum thickness) of the fiber-reinforced tubular body from a cross-sectional photograph using a KEYENCE microscope VHX-5000. (N = 3)
(Density measurement method)
With reference to JIS K 7112: 1999, the density was calculated by an underwater substitution method. The test piece was calculated by cutting a fiber reinforced resin tubular body every 10 mm. (N = 5)

(Measurement method of bending properties)
With reference to JIS K 7074: 1988, the measurement was performed under the following conditions in a three-point bending test (n = 5).
-Bending direction: Bending was performed in a direction perpendicular to the longitudinal direction of the fiber-reinforced resin tubular body and in a direction where the diameter of the fiber-reinforced resin tubular body was the shortest (a direction perpendicular to the parallel portion).
Test piece diameter D: Measure the width of the fiber reinforced resin tubular body in the load direction directly under the indenter with calipers (n = 1)
・ Radius of fulcrum: 2.0mm
・ Indenter radius: 5.0 mm
- distance between supporting points _{L m: (40 ± 8)} × D mm ( the place that is calculated by JIS the solid thickness H calculated in diameter D of the test piece)
-Test piece length l _m : L _m +20 mm
Test speed: 20 mm / min (0.01 L _m ² / 6H in JIS)
・ Bending strength: The bending strength, the distance between fulcrums, the moment of inertia of the cross section of the specimen, and the center-of-gravity distance were obtained by the following formula.
As bending strength σ _max , load P _m at break, distance L _m between fulcrums, cross-sectional secondary moment I of the specimen, and center of gravity distance d,
Calculation was performed using σ _max = FL _m d / 8I.
-Bending elastic modulus (E): It calculated | required from the linear part gradient of the load-deflection curve, the distance between fulcrums, and the cross-sectional secondary moment of a test piece.
That is, assuming that the bending elastic modulus E, the gradient P _m / δ of the straight portion of the load-deflection curve, the distance L _m between the fulcrums, and the cross-sectional secondary moment I of the test piece, E = (L _m ³ / 48I) × P _m / δ
Flexural rigidity (EI): The bending rigidity (EI) was determined from the gradient P _m / δ of the linear portion of the load-deflection curve and the fulcrum distance L _m by the following equation.
^{_{EI = (L m 3/48}} ) × P m / δ

(Strong side pressure)
When a specimen 50 mm ± 2 mm was sandwiched between two parallel flat plates and compressed at a compression speed of 2 mm / min, the maximum load until breakage was measured and divided by the specimen length to determine the lateral pressure strength per unit length. In the case of the substantially circular pipe, the parallel part was tested in parallel with the flat plate (n = 5).
(Surface roughness measurement method)
With reference to JIS B 0601: 2013, it was measured with a stylus type surface roughness measuring instrument (n = 5).

  Examples of the present invention obtained under the above conditions, the structure of the 0 ° fiber layer, braid layer, and outermost layer of the reinforcing fiber (reinforcing fiber) of the fiber reinforced resin tubular body of the comparative example, and the impregnating resin and viscosity Tables 1 and 2 collectively show the manufacturing conditions, the dimensional shape, physical properties, and property evaluation of the obtained fiber-reinforced resin tubular body (product).

  As shown in Table 1, the fiber reinforced resin tubular body obtained by the example of the present invention having an inner layer and an outer layer made of a fiber reinforced resin layer has a practical numerical range for bending physical properties and lateral pressure strength, and has an uneven thickness. Is 0.1 mm or less, and the surface roughness Ra is 1.6 μm. In addition, it is possible to obtain a fiber-reinforced resin tubular body having the above-described excellent physical properties and appearance by manufacturing the fiber-reinforced resin tubular body of the present invention by satisfying predetermined steps and conditions. In comparison with the comparative example described in 1.

The fiber-reinforced resin tubular body of the present invention has a thin wall, low density, high bending strength, bending elastic modulus, bending rigidity, lateral compressive strength, etc. and has surface smoothness. There is no need to polish the diameter, and it may be used in fields that require lightweight and high strength, such as members of sports equipment such as golf shafts, members of fishing rods, and spokes of leisure bicycles.
In particular, since an irregular shape having a flat portion is also possible, it can be used as an elastic member having a rotation suppressing function.
Moreover, the manufacturing method of the fiber reinforced resin tubular body of this invention can be utilized as a method which can manufacture the fiber reinforced resin tubular body of this invention stably and with high productivity.

1 Inner layer 2 Outer layer 3 0 ° fiber reinforced resin layer (reinforcing fiber bundle with an orientation angle of 0 °)
31 0 ° Reinforcing Fiber Bundle 311 0 ° Reinforcing Fiber Bundle Auxiliary Thread 4 Braided Reinforcing Fiber Bundle 40 Winding Bobbin 41 Braided Fiber Bundle with Braid Angle + θ 42 Braided Fiber Bundle with Braid Angle -θ 10 Fiber Reinforced Resin Tubular Body 11 Disc 12 Center Hole 13 0 ° reinforcing fiber bundle guide 16 Traveling track 16a Inner track (S twist)
16b Outer raceway (Z twist)
20, 21 Braid production device (string making machine)
100 0 ° reinforcing fiber bundle braid manufacturing device 200 disc D _l Braid layer Reinforcing fiber single filament (filament) major diameter (μm)
Single yarns D _b braid layer reinforcing fiber diameter (filament) ([mu] m)
F _b Braid layer single yarn Y Longitudinal axis X Circumferential (orthogonal) direction axis Z Circumferential vertical (thickness) direction axis M Mandrel P Braid composition point θ Braid angle

Claims (7)

A fiber reinforced resin tubular body having an inner layer and an outer layer made of a fiber reinforced resin layer, wherein the innermost layer is formed by six or more reinforcing fiber bundles having an orientation angle of 0 ° with respect to the longitudinal axis of the tubular body. A fiber reinforced resin layer,
An outer layer is at least one braided fiber reinforced resin layer in which a reinforcing fiber bundle is braided at a set angle θ of 20 to 50 ° with respect to the longitudinal axis on the outer periphery of the 0 ° fiber reinforced resin layer;
The fiber volume content (Vf) of the 0 ° fiber reinforced resin layer is 30% or more,
A fiber-reinforced resin tubular body, wherein the entire fiber volume content (Vtf) of the tubular body is 50 to 70% and satisfies the following conditions.
<Conditions>
In the cross section orthogonal to the longitudinal direction of the tubular body, the sum ΣD _l (mm) of the long diameter D _l (mm) of the single yarn section of the braided fiber reinforced resin layer in the outermost layer, and the outer peripheral length L (mm) of the tubular body The ratio R (ΣD ₁ / L) of the above is 12 to 41.
ΣD _l (mm) = {single yarn diameter (μm) / cos θ} × (number of fibers per bundle) × (number of fibers) / 1000
(However, _Dl is the long diameter of the single yarn cross section of the braid fiber reinforced resin layer, and θ is the braid angle.)   The innermost layer includes six or more reinforcing fiber bundles having an orientation angle of 0 ° with respect to the longitudinal axis of the tubular body, and includes an auxiliary braid obtained by braiding auxiliary yarns on the outer periphery of the reinforcing fiber bundle. Fiber reinforced resin tubular body. A method for producing a fiber-reinforced resin tubular body formed by impregnating and curing a plurality of fiber layers with different orientation angles of reinforcing fibers with respect to the longitudinal axis,
The manufacturing method of the fiber reinforced resin tubular body characterized by performing the following (1)-(7) processes sequentially.
(1) a step of inserting a mandrel having a shape corresponding to an inner diameter of a desired fiber-reinforced resin tubular body into the center of a tubular body manufacturing apparatus including a braid forming mechanism;
(2) A step of covering the outer periphery of the mandrel using 6 or more reinforcing fiber bundles and forming a 0 ° fiber layer;
(3) A required number of reinforcing fiber bundles are arranged in a tubular body manufacturing apparatus equipped with a braid forming mechanism, and the reinforcing fiber bundles are entangled at a predetermined set angle θ on the 0 ° fiber layer. i), forming at least one braid layer under (ii),
<Conditions>
(i) The tension applied to the reinforcing fiber bundle constituting the braid is 0.01 to 0.20 cN / dtex per fineness (dtex) of the fiber bundle, and the braiding angle θ is set to the left and right objects with respect to the longitudinal direction of the mandrel. Braid the braid as ± 20 ° to ± 50 °.
(ii) In an arbitrary cross section orthogonal to the longitudinal direction of the obtained tubular body, the sum ΣD _l (mm) of the major axis D _l (mm) of the single yarn section of the braided fiber reinforced resin layer in the outermost layer; The braided layer is formed so that the ratio R (ΣD ₁ / L) to the outer peripheral length L (mm) is 12 to 41.
ΣD _l (mm) = {single yarn diameter (μm) / cos θ} × (number of fibers per bundle) × (number of fibers) / 1000
(However, _Dl is the major axis of the single yarn cross section of the braid layer, and θ is the braid angle.)
(4) A step of impregnating the 0 ° fiber layer and the braided layer with a thermosetting resin composition having a viscosity of 150 mPa · s or less to obtain a linear product,
(5) a step of curing the thermosetting resin composition while molding by inserting a linear object into a mold having a hole shape corresponding to the outer shape of the desired fiber-reinforced resin tubular body;
(6) A step of cutting the cured linear product into a predetermined length, and (7) a step of removing the mandrel from the cut linear product to obtain a fiber-reinforced resin tubular body.   In the step (2) of forming the 0 ° fiber layer, the reinforcing fiber bundle for the 0 ° fiber layer is entangled with the auxiliary yarn, and the ratio of the auxiliary yarn to the reinforcing fiber bundle of the 0 ° fiber layer is 1-2. The manufacturing method of the fiber reinforced resin tubular body of Claim 3 which forms the auxiliary thread braid which is fiber volume%. 5. The braided layer forming step (3) is performed in two successive steps, and at least the outermost braided layer is formed so that the ratio R (ΣD ₁ / L) satisfies 12 or more and 41 or less. The manufacturing method of the fiber reinforced resin tubular body of description.   The method for producing a fiber-reinforced resin tubular body according to any one of claims 3 to 5, wherein the reinforcing fiber bundle is a carbon fiber bundle.   In the mandrel insertion step of (1), the fiber-reinforced resin tubular body according to any one of claims 3 to 6, wherein an elongated thermoplastic resin hollow tubular body or rod-shaped body is used as a mandrel. Production method.