JPH086847B2 - Composite pipe and manufacturing method thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a composite pipe in which a plurality of reinforcing layers are laminated and a method for manufacturing the same.

(Prior Art) Conventionally, resin pipes have been widely used because they have excellent characteristics such as being lighter in weight and not rusting as compared with metal pipes. However, this resin pipe is inferior to the metal pipe in pressure resistance and impact resistance. Therefore, assuming that these resin pipes have pressure resistance and impact resistance,
A composite pipe in which a reinforced layer of a resin reinforced with continuous fibers is provided on the outer circumference of a thermoplastic resin pipe has been proposed. For example,
62-773, Japanese Patent Laid-Open No. 57-30030 and Japanese Patent Laid-Open No. 5-30
In JP-A-48120, a composite pipe provided with a reinforcing layer of a thermosetting resin in which continuous fibers are arranged in the longitudinal direction of the pipe is provided on the outer periphery of a thermoplastic resin pipe, and continuous fibers are wound in a substantially circumferential direction of the pipe. Disclosed is a composite tube provided with a reinforced layer of thermosetting resin arranged in turns. These composite pipes are not only excellent in pressure resistance and impact resistance, but also because continuous fibers are arranged in the longitudinal direction of the pipe, thermal expansion and contraction of the pipe is small, and there are few problems due to thermal expansion and contraction of the pipe in the piping line. It has the advantage of

(Problems to be solved by the invention) However, in the above-described conventional composite pipe, since the reinforcing layer is a thermosetting resin, the adhesive force between the thermoplastic resin pipe of the inner layer and the reinforcing layer is weak, and hot water is applied to the composite pipe. When flowed or used at high temperature, there is a problem that peeling easily occurs at the interface between the thermoplastic resin tube and the reinforcing layer due to the difference in linear expansion coefficient between the thermoplastic resin tube of the inner layer and the reinforcing layer. It was

The present invention has been made to solve the above problems, and its purpose is to have excellent pressure resistance and impact resistance, and also when running hot water or when used at high temperature, An object of the present invention is to provide a composite pipe in which the interface between the thermoplastic resin pipe of the inner layer and the reinforcing layer does not easily peel off, and a method for producing the same.

(Means for Solving the Problems) The composite pipe of the present invention includes a thermoplastic resin pipe as an inner layer, a reinforcing layer formed from a thermoplastic resin in which continuous fibers are arranged in a longitudinal direction, and continuous fibers substantially around the pipe. It is characterized in that the reinforcing layers formed from a thermoplastic resin wound in the direction are fused and integrated with each other.

Further, the method for producing the composite tube having the above-mentioned configuration is a tubular body in which the continuous fibers are arranged in the longitudinal direction from a sheet-shaped fiber composite in which a thermoplastic resin is held in continuous fibers composed of a large number of continuous filaments. And a two-layer pipe comprising a thermoplastic resin pipe as an inner layer formed by extruding and laminating a thermoplastic resin on the inner surface of the tubular body in a molten state, and a reinforcing layer in which the continuous fibers of the outer periphery are arranged in the longitudinal direction. And a step of winding and fusing a fiber composite in which a thermoplastic resin is held in continuous fibers made of a large number of continuous filaments around the outer periphery of the two-layer tube. To do.

In the present invention, the thermoplastic resin used for the thermoplastic resin tube of the inner layer is not particularly limited as long as it can be extruded into a tubular shape, and examples thereof include a thermoplastic resin suitable for the purpose of use of the tube. Examples thereof include polyvinyl chloride, chlorinated polyvinyl chloride, polyethylene, polypropylene, polystyrene, polyamide, polycarbonate, polyphenylene sulfide, polysulfone, and polyether ether ketone. These thermoplastic resins may be used alone or as a mixture of two or more. Further, additives such as heat stabilizers, plasticizers, lubricants, antioxidants, ultraviolet absorbers, pigments, inorganic fillers, reinforcing fibers, fillers, processing aids, modifiers and the like may be added.

The thermoplastic resin previously held by the continuous fibers constituting the first reinforcing layer and the second reinforcing layer does not need to be the same as the thermoplastic resin of the inner layer, and may be a thermoplastic resin having a good fusion property. Good.

When the thermoplastic resin of the second reinforcing layer is a thermoplastic resin having a better adhesiveness to the adjacent first reinforcing layer than the adhesiveness to the thermoplastic resin of the inner layer, the adhesiveness between the layers is high, A composite tube with excellent reliability can be obtained. The term "fusing property" as used herein means that both resins are heated to a molten state and then pressure-bonded, and after cooling, the fused interface is not easily broken.

The reinforcing layer is a first reinforcing layer composed of a reinforcing fiber in which continuous fibers are arranged at least in the longitudinal direction and a thermoplastic resin, and a reinforcing fiber and a thermoplastic resin in which continuous fibers are arranged at least approximately in the circumferential direction of the pipe. A second reinforcing layer consisting of: First reinforcement layer and second
Both the reinforcing layer and the reinforced layer may be formed by adding a cloth and a woven fabric, each of which is a continuous fiber or a finite length fiber arranged in different directions.

As the continuous fiber arranged in the longitudinal direction of the tube and the continuous fiber wound in the substantially circumferential direction of the tube, a roving-like or strand-like one made of continuous filaments having a diameter of 1 to several tens of μm is used. As this fiber, glass fiber,
All of the continuous fibers that can be used as reinforcing fibers for resins such as synthetic or natural organic fibers such as carbon fibers, metal fibers, aramid fibers, and vinylon are preferably used.

The continuous fibers arranged in the longitudinal direction of the pipe and the continuous fibers wound in the substantially circumferential direction of the pipe may be the same type of fibers or different types of fibers. Further, the continuous fiber is preferably in a state of being sufficiently impregnated with a thermoplastic resin between the filaments and held, and the fact that such continuous fiber reinforces the watertightness of the pipe and It is preferable in that it enhances the adhesiveness between the continuous fiber and the thermoplastic resin, and it is preferable that surface treatment such as impregnating the thermoplastic resin between the filaments in advance is performed to enhance the adhesiveness between the continuous fiber and the resin. It is preferably used.

The fusion-bonding integration of the first reinforcing layer and the second reinforcing layer is performed by the first strengthening of the thermoplastic resin in which continuous fibers are arranged in the longitudinal direction of the pipe formed on the outer circumference of the thermoplastic resin pipe of the inner layer. A continuous fiber composed of a large number of filaments holding a thermoplastic resin is wound around the outer periphery of the layer while heating one layer or multiple layers while heating, or after winding, a first reinforcing layer and a second reinforcing layer by a heating means. It is obtained by heating a thermoplastic resin impregnated with continuous fibers forming a layer and fusing each other.

The sheet-shaped fiber composite of the first reinforcing layer arranged in the longitudinal direction of the composite pipe of the present invention is made to have a thermoplastic resin impregnated between filaments of continuous fibers and held, and formed into a sheet by heating and pressing. It is a thing. Then, in this sheet-shaped fiber composite, continuous fibers are arranged substantially parallel to the longitudinal direction of the sheet. The width of the sheet-shaped fiber composite is formed to be approximately equal to the outer circumference of the two-layer tube provided with the reinforcing layer to be formed, and the thickness is determined by the desired thickness of the reinforcing layer,
Those having a thickness of about 0.1 mm to 3 mm are preferably used. Further, the fibers in the sheet-shaped fiber composite need continuous fibers arranged substantially parallel to the longitudinal direction of the sheet, but in addition, fibers having a finite length arranged in a crossing direction such as a direction orthogonal to the continuous fibers. A fiber composite in which a thermoplastic resin is held by a cloth-shaped fiber material composed of The amount of fibers in this sheet-shaped fiber composite is 5 to 70% by volume. If it is less than 5% by volume, a sufficient reinforcing effect cannot be obtained, and if it exceeds 70% by volume, the fusion bonding property between the thermoplastic resin pipe of the inner layer and the second reinforcing layer is lowered and the interface is not sufficiently fused.

The fiber composite used for forming the second reinforcing layer by arranging the continuous fibers in the substantially circumferential direction of the tube is a tape in which a thermoplastic resin is impregnated and held between filaments of the continuous fibers, and the tape is formed by heating and pressing. In the fiber composite in the shape of a strip, a string, etc., continuous fibers are arranged substantially parallel to the longitudinal direction of the fiber composite. The width and thickness of this fiber composite are not particularly limited, but when a string-shaped fiber composite is used, the diameter is 0.5 to 5 mm.
Those having a width of about 10 to 100 mm and a thickness of about 0.1 mm to 3 mm are preferably used when a tape-shaped fiber composite is used. Further, the fibers in the tape-shaped fiber composite must have continuous fibers arranged substantially parallel to the longitudinal direction thereof, but in addition, a fiber having a finite length arranged in a crossing direction such as a direction orthogonal to the continuous fibers may be used. It may contain fibers.

The method of impregnating the thermoplastic resin between the filaments to retain the thermoplastic resin in the continuous fiber is as follows: (i) Flowing the powdery thermoplastic resin with a roving-like or strand-like continuous fiber material composed of a large number of filaments. A method of passing through the bed, (ii) passing through a bath of a liquid in which the powdery thermoplastic resin is dispersed, impregnating the powdery thermoplastic resin between the filaments, and subsequently heating it above the melting temperature to form fibers. A method is to integrate the resin, or impregnate it and then dry it, and then heat it to a temperature not lower than the melting temperature to integrate the fiber and resin, and form it into a desired shape such as a sheet, tape, or string. It is preferably adopted. Further, in the case of a resin having a low melt viscosity, it is possible to impregnate the continuous fiber material by a method of immersing the continuous fiber material in a bath of the molten resin.

When an outer layer is provided on the outer periphery of the reinforcing layer, the thermoplastic resin used for the outer layer may be any thermoplastic resin without particular limitation, but the thermoplastic resin used for the boundary reinforcing layer and the fusion bonding property. It is preferable to use a good thermoplastic resin in order to obtain a composite tube in which the reinforcing layer and the outer layer are firmly fused and integrated.

 Hereinafter, the present invention will be described with reference to FIGS.

FIG. 1 is a perspective view of an embodiment of the composite pipe according to the present invention with the end surface peeled off. In this figure, 1 is a composite pipe, and this composite pipe 1 has a first reinforcing layer 3 in which continuous fibers are arranged in the longitudinal direction of the pipe on the outer circumference of a thermoplastic resin pipe 2 which is an inner layer serving as a core material. It is composed of a second reinforcing layer 4 in which continuous fibers are arranged on the outer periphery of the reinforcing layer 3 in a substantially circumferential direction of the tube, and an outer layer 5 in which the outer periphery of the second reinforcing layer 4 is coated with a thermoplastic resin. .

2 to 4 are explanatory views showing an example of a manufacturing process of the composite pipe according to the present invention. In these drawings, the manufacturing process is attached to the extruder 11 and the tip of the extruder 11, An inner core 12 arranged at the axial center and extending to the forward side, an inner mold 13 arranged so as to form an annular gap on the outer periphery of the inner core 12, and an annular gap 14 on the outer periphery of the inner mold 13. Shaping rolls 15 and 16 arranged so as to form the inner mold 13
The outer die 17 arranged concentrically with the inner core 12 so that an annular gap that is concentric with the gap 14 is formed on the outer periphery of the outer periphery of the outer die 17, and the fiber composite in the laminated tube 10b formed by the outer die 17. A heating device that includes a winding device 18 that winds the body 9 and that is arranged near the inner mold 13 to heat the sheet-shaped fiber composite body 8.
23, heating means 24 for heating the two-layer laminated tube 10b and the wound fiber composite 9, and an extruder 19 for supplying a thermoplastic resin.
And a coating die 20 which is attached to the tip of the extruder 19 and which coats the outer periphery of the reinforcing layer 4 with a thermoplastic resin to form the outer layer 5.
And a cooling device 21 for cooling and sizing the four-layer laminated composite pipe 1 having an outer layer formed therein, and a take-off machine 22 for taking the formed composite pipe 1 together.

 Next, a method for manufacturing the composite pipe of the present invention will be described.

First, the sheet-shaped fiber composite body 8 is continuously fed from the rear of the inner die 13 through the outer periphery of the inner die 13 and the annular gap 14 formed by the shaping rolls 15 and 16, and the continuous fiber is The tubular body 10a arranged in the longitudinal direction of the pipe is molded (FIGS. 3 to 4). At this time, the heating of the sheet-shaped fiber composite 8 by the heating means 23 can facilitate the molding of the tubular body 10a, and the shaping rolls 15 and 16 are heated to the softening temperature of the sheet-shaped fiber composite 8 or higher. May be.

Subsequently, the tubular body 10a is introduced into the annular gap formed by the inner die 13, the inner core 12 and the outer die 17. The melt-plasticized thermoplastic resin extruded from the extruder 11 is formed into a tubular shape by the inner mold 13, and is extruded and laminated on the inner surface of the tubular body 10a inside the inner mold 13, and the outer periphery of the thermoplastic resin of the inner layer is formed. A two-layer tube 10b is formed by fusing the first reinforcing layer 3 of a thermoplastic resin in which continuous fibers are arranged in the longitudinal direction of the tube.

Then, the winding device 18 is rotated around the two-layer tube 10b to wind the fiber composite 9, and the surfaces of the two-layer tube 10b and the fiber composite 9 are heated by the heating means 24 to fuse the two. , A second reinforcing layer 4 of thermoplastic resin in which the continuous fibers are arranged approximately in the circumferential direction of the tube. By winding the fiber composite 9 while the surface of the two-layer tube 10b is in a fusion-bonded state, a three-layer tube 10c in which both are fused is obtained.

Subsequently, a thermoplastic resin is introduced into the outer periphery of the second reinforcing layer 4 of the three-layer pipe 10c from the extruder 19 through the coating die 20, and the outer layer 5 is provided on the outer periphery of the reinforcing layer 4, and then the water tank. The composite pipe 1 is manufactured by cooling and sizing with a cooling device 21 such as the above, and taken up by a take-up machine 22.

In order to prevent the two-layer tube 10a from being deformed when the fiber composite body 9 is wound and fused around the outer periphery of the two-layer tube 10a, the inner core 12 is projected into the two-layer tube 10a in the extrusion direction. Then, the fiber composite body 9 is wound around the outer circumference of the two-layer tube 10a at a position outside the inner core 12, or the two-layer tube 10a is wound from the tip of the inner core 12.
It is also possible to adopt a method in which cooling air is blown into the interior of the fiber to wind the fiber composite 9 while cooling the inner surface of the two-layer tube 10a. Further, in the above, while the composite pipe is taken by the take-off machine, an example of continuously producing by performing a series of production steps is shown, but a two-layer pipe is produced in another process in advance, The second reinforcing layer may be molded later. Further, in the above, an example of heating the sheet-shaped fiber composite has been shown, but the heating operation may be omitted, and the installation position of the heating means is not limited to the above example.

Further, in the above, the composite pipe is arranged from the inner layer of the thermoplastic resin to the outer periphery thereof, the first reinforcing layer in which continuous fibers are sequentially arranged in the longitudinal direction of the pipe, and the continuous fibers are arranged in a substantially circumferential direction of the pipe. Although the example including the second reinforcing layer and the outer layer of the thermoplastic resin has been described, the arrangement of the reinforcing layer of the composite pipe is not limited to this example, and the number of the reinforcing layers is not limited to the above example. Each of the first reinforcing layer and the second reinforcing layer may be plural, and the outer layer of the thermoplastic resin may not be provided on the outer periphery of the reinforcing layer.

(Function) The composite pipe of the present invention is provided with the outer periphery of the thermoplastic resin pipe of the inner layer,
The continuous fibers consist of a first reinforcing layer arranged in the longitudinal direction of the pipe and a second reinforcing layer in which the continuous fibers are arranged substantially in the circumferential direction of the pipe, and the thermoplastic resin at the boundary of each of these layers is fused and integrated. It has become. Therefore, the first, which is arranged in the longitudinal direction of the pipe,
The continuous fiber of the reinforcing layer suppresses the linear expansion of the tube, reduces the thermal contraction, and makes it difficult for peeling to occur at the interface of each layer, and the second reinforcing layer arranged substantially in the circumferential direction of the tube The pressure resistance and impact resistance are improved.

Further, the method for producing a composite pipe of the present invention comprises a step of forming a tubular body in which continuous fibers of a fiber composite in which a thermoplastic resin is held in continuous fibers composed of a large number of filaments are arranged in the longitudinal direction of the pipe. A step of extruding and laminating a thermoplastic resin tube in a molten state on the inner surface of a tubular body to form a two-layer tube, and a fiber composite in which the thermoplastic resin is held in continuous fibers made of a number of filaments on the outer periphery of the two-layer tube Since it comprises the process of winding and fusing, the composite pipe in which the thermoplastic resin is fused and integrated at the boundary of each layer is easily manufactured.

(Example) The Example of this invention is described based on drawing.

Example 1 1) Preparation of fiber composite As shown in FIG. 5, 10 of roving glass fiber (4400tex) 6 composed of filaments having a diameter of 23 μm was used.
A powdery thermoplastic resin composition 7 containing a vinyl acetate-vinyl chloride copolymer resin as a main component and having a particle diameter of about 250 μm.
Is passed through the fluidized bed 30 fluidized by the air 30a to adhere the powdery thermoplastic resin between the filaments of the glass fiber 6 and then heated to about 180 ° C. By heating and pressurizing with 31, the thermoplastic resin was melted and integrated with the glass fiber 6, and a fiber composite 6a having a thickness of 0.6 mm was produced. The volume ratio between the thermoplastic resin and the glass fiber of this fiber composite is as follows: thermoplastic resin: glass fiber =
It was 75:25.

The fiber composite 6a was cut to prepare a sheet-shaped fiber composite 8 in which continuous glass fibers having a width of 107 mm and a thickness of 0.6 mm were arranged in the longitudinal direction. Also, the fiber composite 6a is cut into a width of 20
A tape-shaped fiber composite 9 was prepared in which continuous glass fibers having a thickness of 0.6 mm and a thickness of 0.6 mm were arranged in the longitudinal direction.

2) Manufacture of composite pipe Using the sheet-shaped fiber composite 8 and the tape-shaped fiber composite 9 described above, a composite pipe was manufactured by the steps shown in FIG.

The sheet-shaped fiber composite body 8 was formed into a tubular body 10a having an outer diameter of about 34 mm and a thickness of 0.6 mm by the shaping rolls 15 and 16 while being heated by blowing hot air with a hot air generator used as the heating means 23.

Subsequently, the tubular body 10a is attached to the inner mold 13 (temperature = about 210 ° C.).
Inner core 12 (Temperature = about 210 ℃) and outer mold 17 (Temperature = about 210 ℃)
The chlorinated polyvinyl chloride resin, which has been introduced into an annular gap composed of the (3) and is melted and plasticized by the extruder 11 and formed into a tube by the inner die 13, inside the outer die 17 is a tubular body 10a.
Chlorinated polyvinyl chloride resin tube (thickness: about 1.5 mm) is laminated by extrusion on the inner surface and the inner layer 2 is a chlorinated polyvinyl chloride resin tube. Continuous glass fibers are arranged on the outer circumference of the tube. A two-layer pipe 10a having an outer diameter of 34 mm and having a first reinforcing layer 3 (having a thickness of about 0.6 mm) of vinyl copolymer resin fused thereto was formed.

Then, the tape-shaped fiber composite 9 is wound around the outer circumference of the two-layer tube 10a by using a winding device 18 to continuously wind the continuous glass fibers at an angle of 10.5 ° with respect to the longitudinal direction of the tube, and The two-layer tube 10a and the sheet-shaped fiber composite 8 are heated by the heating means 24 of the infrared heater, and the two are fused and integrated to form the two-layer tube 10a.
A second reinforcing layer 4 having a thickness of about 0.6 mm of a vinyl acetate-vinyl chloride copolymer resin, in which continuous glass fibers were arranged in a substantially circumferential direction of the tube, was provided on the outer circumference of the.

Subsequently, the three-layer laminated pipe 10c provided with the reinforcing layer 4 is introduced into the coating mold 20, and the polyvinyl chloride resin melt-plasticized by the extruder 19 is extruded onto the outer periphery of the reinforcing layer 4 of the laminated pipe 10c. After coating and providing the outer layer 5 (thickness: about 1 mm), cooling sizing was performed by the cooling device 21 to obtain the four-layer composite pipe 1. The composite pipe 1 was continuously manufactured by performing the above series of steps while being taken by the take-up machine 22.

The obtained composite pipe 1 has an inner diameter of about 30.8 mm and an outer diameter of about 37.2 mm.
mm laminated tube, the first reinforcing layer 3 of vinyl acetate-vinyl chloride copolymer resin in which continuous glass fibers are arranged on the outer periphery of the inner layer 2 of the chlorinated polyvinyl chloride resin tube in the longitudinal direction of the tube.
And a second reinforcing layer 4 of vinyl acetate-vinyl chloride copolymer resin, in which continuous glass fibers are arranged substantially in the circumferential direction of the tube, is fused to the outer periphery of the reinforcing layer.
It was a four-layer composite pipe in which the outer layer 5 of the polyvinyl chloride resin pipe was fused to the outer periphery of the composite pipe.

Comparative Example According to the manufacturing method disclosed in JP-A-59-48120, continuous glass fibers were arranged in the longitudinal direction of the tube on the outer periphery of the inner layer of a chlorinated polyvinyl chloride resin tube having an inner diameter of 30 mm and an outer diameter of 34 mm. An unsaturated polyester resin (thermosetting resin) is provided with a reinforced layer (thickness of about 0.6 mm) of continuous unsaturated polyester resin (thermosetting resin), and continuous glass fibers are arranged around the outer periphery of the reinforced layer approximately in the circumferential direction of the tube. Reinforcing layer (thickness: approx.
0.6 mm) was provided, and an outer layer of polyvinyl chloride resin (thickness: about 1 mm) was fused to the outer periphery of the reinforcing layer to form a composite pipe.

(Evaluation) The composite pipes obtained in Example 1 and Comparative Example were cut to a length of 1 m, and hot water (90 ° C) and cold water (25 ° C) were put into each composite pipe.
A cold-heat repeated test was conducted in which water was passed alternately at 15-minute intervals.

When the state after 5000 cycles of the above-mentioned test was observed, no abnormality was found in the composite pipe obtained in Example 1, but the composite pipe obtained in Comparative Example was the inner layer chlorinated polyvinyl chloride resin pipe. Peeling occurred at the interface of the unsaturated polyester resin.

(Effects of the Invention) The composite pipe of the present invention is provided with two layers of reinforcing layers in which continuous fibers are arranged in the longitudinal direction and the substantially circumferential direction of the pipe on the outer periphery of the inner layer of the thermoplastic resin of the inner layer and melted. Since they are attached and integrated, the heat shrinkage of the tube is small, and the pressure resistance and impact resistance are excellent. Further, even when hot water is flowed or used at high temperature, peeling does not occur at the boundary interface between the layers of the composite pipe.

Further, the method for producing a composite pipe of the present invention comprises a step of forming a tubular body in which continuous fibers of a fiber composite in which a thermoplastic resin is held in continuous fibers composed of a large number of filaments are arranged in the longitudinal direction of the pipe. A step of extruding and laminating a thermoplastic resin tube in a molten state on the inner surface of a tubular body to form a two-layer tube, and a fiber composite in which the thermoplastic resin is held in continuous fibers made of a number of filaments on the outer periphery of the two-layer tube Since it comprises the step of winding and fusing, the composite pipe as described above can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of a composite pipe according to the present invention, FIG. 2 is an explanatory view showing an example of steps of a method for producing a composite pipe according to the present invention, and FIG. 3 is for forming a two-layer pipe. Sectional drawing for explaining the process, FIG. 4 is a plan view for explaining the step of forming a reinforcing layer from the sheet-shaped fiber composite, and FIG. 5 is an explanatory view for explaining the step of manufacturing the fiber composite. is there. 1; Composite tube, 2; Inner layer thermoplastic resin tube 3; First reinforcing layer, 4; Second reinforcing layer 8; Sheet-shaped fiber composite 9; Fiber composite, 10a; Tubular body 11, 19; Extrusion Machine, 18; winding device 20; coating mold 21; cooling device, 22; take-up machine

Claims (2)

[Claims] 1. A thermoplastic resin tube as an inner layer, a thermoplastic resin reinforcing layer in which continuous fibers are arranged in a longitudinal direction of the tube, and a thermoplastic resin in which continuous fibers are wound and arranged in a substantially circumferential direction of the tube. A composite pipe in which layers are fused and integrated with each other. 2. (a) A step of forming a tubular body in which the continuous fibers are arranged in the longitudinal direction from a sheet-shaped fiber composite in which a thermoplastic resin is held by continuous fibers composed of a large number of continuous filaments, b) a step of extruding and laminating a thermoplastic resin in a molten state on the inner surface of the tubular body to form a two-layer tube,
(C) A composite pipe including a step of winding and fusing a fiber composite in which a thermoplastic resin is held on continuous fibers composed of a large number of continuous filaments around the outer periphery of the two-layer pipe. Manufacturing method.