JP2001050435A - Compound flexible pipe and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase partial reinforcement, and unify partial composition by continuously changing a constituting weight ratio per pitch of a material in a longitudinal direction. SOLUTION: Hard thermoplastic resin and polyolefin thermoplastic elastomer are supplied from hoppers 11, 12 which are corresponding thereto, and are simultaneously extruded as a zonal body 3 from a dies (a) of an extruder A. The zonal body 3 is formed in a nearly square shaped cross section as a whole, and hard thermoplastic resin 1 and polyolefin thermoplastic elastomer 2 are extruded in a condition adjacently integrated in the pipe longitudinal direction. In this process, a cooperative extruding perfonnance is carried out while changing a constituting weight ratio of a used material. For changing the constituting weight ratio, it is continuously changed in the longitudinal direction. For changing the constituting weight ratio of the used material, a ratio of an extruding speed (an extruding quantity) of the extruder for carrying out the cooperative extruding performance is changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite flexible pipe manufactured by co-extrusion of materials having different rigidities and a method for manufacturing the same, and more particularly to a method for industrially mass-producing a composite flexible pipe for a joint. It is a very useful technology.

[0002]

2. Description of the Related Art Conventionally, there has been a method of manufacturing a composite flexible tube in which a soft resin and a hard resin are coextruded in a belt shape and spirally wound around a core material to form a tubular body. The composite flexible pipe manufactured by this method is mainly composed of a soft resin and a hard resin, and has a structure in which the hard resin is spirally arranged. The composite flexible tube mainly exhibits flexibility, elasticity, and the like by the soft resin, and the reinforcing effect is obtained by the helical hard resin. In the above manufacturing method, it is difficult to change the winding speed by the core material in accordance with the extrusion speed (extrusion amount).
The pitch of the hard resin arranged in a spiral was substantially constant. The composition weight ratio of the material for each pitch was also constant.

[0003] Such a composite flexible pipe may be used alone, but is often used as a flexible joint for connecting another hard resin pipe or the like. In this case, the composite flexible pipe is joined to another hard resin pipe via a flange member or the like or directly, and in any case, it has a joint with a hard material.

Then, the flexible joint is bent,
If deformation such as eccentricity (shear) occurs in the flexible portion, deformation stress concentrates near the joint of the composite flexible tube with the hard material, and breakage or the like easily occurs in that portion. For this reason, there is a limit to increasing the durability and the allowable displacement when the pitch of the helical hard resin is constant.

[0005] From such a background, in a rubber flexible pipe reinforced with a steel coil or a resin flexible pipe reinforced with a helical hard resin, the pitch of the steel coil or the helical hard resin is set to be long. There are techniques for changing the degree of reinforcement by changing the direction. Regarding the former, for example, Japanese Unexamined Patent Publication No. 9-296887 discloses a rubber flexible joint having a coiled reinforcing wire whose pitch is gradually reduced toward an end. Regarding the latter, Japanese Patent Application Laid-Open No. H11-94140 discloses a resin hose manufactured by changing the pitch of a resin hose having an equal pitch by using a spiral steel material whose pitch is gradually reduced toward an end. It has been disclosed. In both technologies, by increasing the reinforcing effect of the reinforcing material at the ends thereof, it is possible to effectively reinforce the vicinity of the ends where stress is likely to be concentrated when a bending force or a shearing force is generated, thereby forming a flexible pipe. The durability and permissible displacement are increased.

[0006]

However, in the former technique, since a coil-shaped reinforcing wire is used, a complicated process is required for embedding in rubber, and it is impossible to manufacture continuously. . In the latter technique, although an extruded resin hose having an equal pitch can be used as a raw material, it is difficult to continuously manufacture the resin hose due to a complicated processing process. Therefore, the characteristics of the resulting resin hose are also limited.

As described above, it is difficult to continuously produce a composite flexible pipe while changing the pitch of the reinforcing material in any of the conventional techniques, and a continuous production method is used as an industrial mass production technique. Longed for. Alternatively, there has been a long-felt need for a composite flexible tube which is effective for avoiding the above-mentioned stress concentration and which can be manufactured continuously.

[0008] On the other hand, since a fusion welding method such as an EF method or a bad joint method is usually used for connecting the hard resin pipe, a flexible pipe (flexible joint) for connecting the hard resin pipe is used. Also, it is desirable that the joint has a uniform resin composition. However, in a conventional composite flexible tube in which only the pitch is changed, it is difficult to sufficiently increase the constituent weight ratio of the hard resin at the end. For this reason, the soft resin is easily peeled off at the joint, and this also causes insufficient durability and the like.

Accordingly, an object of the present invention is to provide a composite composite which can be manufactured continuously and can partially increase the reinforcement and partially homogenize the composition by changing the partial composition. An object of the present invention is to provide a tube and a method for manufacturing the tube.

[0010]

The above object can be achieved by the present invention as described below.

That is, the composite flexible tube of the present invention is composed of two or more materials having different rigidities, and at least one of the composite flexible tubes is helically arranged at a substantially constant pitch. Is characterized in that the component weight ratio for each pitch has a portion that changes in the longitudinal direction. Here, the “substantially constant pitch” means that the pitch is allowed to change within a range in which the spirally arranged materials are substantially individually accommodated in sections in which the longitudinal section of the pipe is sectioned at regular intervals. It means to do. Therefore, “each pitch” may correspond to each section.

In the above, it is preferable that the constituent weight ratio for each pitch is continuously changed in the longitudinal direction.

Further, it is preferable that the material is composed of a hard thermoplastic resin and a thermoplastic elastomer.

In this case, it is preferable that the hard thermoplastic resin is a hard polyolefin and the thermoplastic elastomer is a polyolefin-based thermoplastic elastomer.

Further, it is preferable that the constituent weight ratio of the hard thermoplastic resin per pitch is the smallest at the center of the tube and the largest at the end of the tube.

At this time, it is preferable that the rigid thermoplastic resin near the pipe end has a structure joined in the longitudinal direction.

On the other hand, the production method of the present invention comprises a step of spirally winding a core material and forming a tubular body while co-extruding two or more materials having different stiffness into a strip shape. In the production method, co-extrusion is performed while changing the constituent weight ratio of the material. Here, the band shape means a continuous body having a width corresponding to a helical pitch, and is not limited to a flat cross-sectional shape.

In the above, it is preferable that the co-extrusion is performed while maintaining the extrusion speed of the co-extrusion and the outer shape of the extrusion cross section substantially constant.

Further, it is preferable that the material is composed of a hard thermoplastic resin and a thermoplastic elastomer.

[Function and Effect] The composite flexible tube of the present invention has a portion in which the constituent weight ratio per pitch of the material changes in the longitudinal direction, but is formed at a substantially constant pitch. Can be produced continuously by co-extrusion. In addition, by changing the composition weight ratio of two or more kinds of materials having different rigidities, it is possible to freely change the partial composition, to increase the partial reinforcement and to homogenize the partial composition (for example, to harden the hard material). (The composition weight ratio is set to approximately 1).

When the constituent weight ratio for each pitch changes continuously in the longitudinal direction, the composition of materials having different stiffness changes continuously, so that deformation such as bending and eccentricity (shear) occurs. When this occurs, partial stress concentration is unlikely to occur, so that the durability and allowable displacement of the flexible pipe can be further increased.

When the above-mentioned material is composed of a hard thermoplastic resin and a thermoplastic elastomer, any of the materials can be suitably melt-extruded, and the thermoplastic elastomer exhibits good flexibility and hard thermoplastic resin. Resin has the effect of reinforcing it.

In particular, when the hard thermoplastic resin is a hard polyolefin and the thermoplastic elastomer is a polyolefin-based thermoplastic elastomer, the co-extrusion is easy because the heat melting properties are close to each other. Will also be good. Further, it is advantageous for recycling, and harmful components are hardly generated at the time of combustion.

When the constituent weight ratio of the hard thermoplastic resin per pitch is the smallest at the center of the tube and the largest at the end of the tube, the rigid thermoplastic resin is connected when deformation such as bending or eccentricity (shear) occurs. The reinforcement of the end of the tube, which is the joint with the hard resin tube, increases, and the displacement hardly occurs at that portion. The durability at the end of the tube is increased, and the overall durability and the allowable displacement are further improved. be able to. Further, flexibility is suitably exhibited by the central portion of the tube in which the constituent weight ratio of the hard thermoplastic resin is small.

In particular, when the hard thermoplastic resin near the pipe end has a structure joined in the longitudinal direction, the hard thermoplastic resin is exposed over the entire circumference of the pipe end face, and the hard thermoplastic resin is exposed on the outer peripheral face near the pipe end. Since the exposed amount of the hard thermoplastic resin becomes large, a fusion welding method such as an EF method or a bad joint method can be suitably performed, and the strength of the pipe end becomes particularly high. In other words, conventionally, a rigid resin pipe (connecting pipe) joined to both ends of a flexible pipe has been used as a flexible joint, but in the above case, there is no need to join the connecting pipe. Can also be simplified.

On the other hand, according to the production method of the present invention, coextrusion is carried out while changing the compositional weight ratio of the materials. Therefore, the composite flexible pipe of the present invention having the above-described effects can be obtained by using conventional equipment. And can be manufactured continuously. Therefore, the production method of the present invention is extremely useful as a technique for industrially mass-producing composite flexible pipes for joints.

When co-extrusion is performed while maintaining the extrusion speed and the cross-sectional profile of the co-extrusion substantially constant, the pitch can be made constant when the belt is spirally wound around the core material. Continuous manufacturing is easier, and
Since the profile of the extruded cross section is substantially constant, it is possible to manufacture a composite flexible tube having less irregularities and steps on the surface.

When the material is composed of a hard thermoplastic resin and a thermoplastic elastomer, as described above, a composite flexible pipe particularly useful as a composite flexible pipe for a joint (for connecting a pipe) is manufactured. be able to.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in the order of a method of manufacturing a composite flexible tube, materials used, a structure of the composite flexible tube, and the like.

(Method of Manufacturing Composite Flexible Tube) The method of manufacturing a composite flexible tube according to the present invention comprises spirally winding a core material into two or more materials while coextruding two or more materials having different rigidities into a tubular shape. And forming a body. This step itself is known, and is disclosed in JP-A-52-138576 and JP-A-52-138576.
Since the details are described in 138570 and the like, only the outline will be described. In this embodiment, a case where a hard thermoplastic resin and a polyolefin-based thermoplastic elastomer are co-extruded using an apparatus as shown in FIG.

First, hoppers 11, 1 corresponding to a hard thermoplastic resin and a polyolefin-based thermoplastic elastomer are used.
2 and simultaneously co-extruded as a strip 3 from the die a of the extruder A. At this time, the band 3 is as shown in FIG.
As shown in (1), the rigid thermoplastic resin 1 and the polyolefin-based thermoplastic elastomer 2 have a substantially square cross-sectional shape (outer shape) as a whole, and are extruded in a state where they are integrated right and left (in the longitudinal direction of the pipe). The inside of the extruder A is heated according to the melting point of the material used (for example, 130 to 260 ° C.), extruded as a viscous soft material, and spirally wound around a former B as a core material. The former B includes a cantilevered metal core and a plurality of flexible feed rollers disposed around the core metal and rotatably held via a holding frame. Each feed roller is arranged in a gentle spiral shape, so that the rotation of the feed roller causes the belt-shaped body 3 to be wound spirally and sent to the downstream side. In addition, each feed roller rotates at the same speed by the drive shaft 17 rotating by the input from the pulley 20 and being transmitted by the gear in the gear box 10.

The spirally wound tubular body 14 can be cooled as it is to form a composite flexible tube H if both ends 3a of the strip 3 are completely fused. However, it is preferably sent to the heating device 6, and the both ends 3a are fused by heating. Then, it is cooled by the cooling water 7 supplied from above, and further cooled by the cooling water in the cooling water tank 8 to form the composite flexible pipe H.

The present invention is characterized in that in the above step, co-extrusion is performed while changing the constituent weight ratio of the materials used. It is preferable to change the constituent weight ratio continuously in the longitudinal direction. For flexible joints, the constituent weight ratio of the hard material for each pitch of the hard material is the smallest at the center of the pipe, It is preferable to increase the weight ratio at the tube end so that the rigid thermoplastic resin near the tube end is joined in the longitudinal direction.

To change the composition weight ratio of the materials used,
A method of changing the ratio of the extrusion speed (extrusion amount) of an extruder that performs co-extrusion can be adopted. The extruder may be any extruder that can extrude two or more materials alone or in combination, and various extruders (or extrusion mechanisms) such as a single-screw extruder and a twin-screw extruder are used in combination. Therefore, to change the extrusion speed of each extruder, it is sufficient to change the rotation speed of the screw (possible by controlling the frequency of the motor, etc.), and if the relationship between the rotation speed and the extrusion amount is grasped, the rotation speed can be controlled. Can control the amount of extrusion. However, since the relationship between the rotation speed and the extruded amount (extruded volume) may not be a linear function, it is necessary to change the constituent weight ratio of the used material while keeping the total amount of the extruded volume of the co-extrusion substantially constant. It is preferable to perform rotation speed control that reflects the above relationship as a function.

As the die (die) of the extruder,
Various bases capable of co-extruding the material from the extruder used together can be used, and a base having a shape corresponding to the cross-sectional shape of the band 3 is used. Each material extruded from each extruder is guided in a softened state to the outlet of the die, and is integrated inside the die or near the die outlet. At this time, it is preferable that the materials are co-extruded at a temperature at which the materials are integrated by fusion or the like.

FIGS. 2 (a) to 2 (d) show an example of the strip 3 formed by co-extrusion of two kinds of materials so that the change in the composition weight ratio can be seen. In addition, FIG.
FIG. 2 (c) shows an example in which the external shape of the co-extrusion extrusion cross section is substantially constant, and FIG. 2 (d) shows an example in which the area of the extrusion cross section increases with an increase in the constituent weight ratio of the hard thermoplastic resin. is there.

FIG. 2A shows a case where the outer shape of the cross section is substantially square as described above, and the die has, for example, a die channel (die land) having a square cross section on the outlet side (die lip side). Inside, a square flow path is divided at the center (equivalent to the center drawing of FIG. 2 (a)), and a flow path having a junction where flow paths from the respective extruders used together are used.

FIG. 2B shows a case where the cross-sectional shape is a parallelogram, in which both end portions 3a of the belt-like body are inclined to facilitate fusion. The die has, for example, a die flow path having a parallelogram cross section on the outlet side, and a parallelogram flow path is divided in the center thereof in parallel with the inclined surface at the center (see the center drawing in FIG. 2B). Equivalent), those having a junction where the flow paths from the extruders to be used together are used.

FIG. 2 (c) has the same cross-sectional shape as that shown in FIG. 2 (b), and the rigid thermoplastic resin 1 has a circular cross-sectional shape. The die has, for example, a die flow path having a parallelogram cross section on the outlet side, and a circular opening provided at the center of the parallelogram flow path inside the die flow path (see FIG. Equivalent), those having a junction where the flow paths from the extruders to be used together are used.

FIG. 2D shows an example in which only the extrusion volume of the hard thermoplastic resin 1 is increased while the thermoplastic elastomer 2 remains in a shape close to a flat parallelogram. As the base, for example, the die exit (die lip)
A circular opening is provided at the center of the parallelogram die outlet (similar to the left-hand drawing in FIG. 2D), and the hard thermoplastic resin 1 is discharged from the circular opening to the outside die. What can co-extrude the thermoplastic elastomer 2 from the outlet is used.

In order to manufacture a composite flexible pipe in which the constituent weight ratio of the hard material per pitch is the smallest at the center of the pipe and the largest at the pipe end, the constituent weight ratio was changed from the maximum to the minimum. Thereafter, the continuum is increased from the minimum to the maximum again, and this is repeated to produce a continuous body, which may be cut at a position where the constituent weight ratio is the maximum. To manufacture a composite flexible pipe having a structure in which the rigid thermoplastic resin near the pipe end is joined in the longitudinal direction, when maximizing the constituent weight ratio,
The constituent weight ratio of the hard thermoplastic resin may be 90% by weight or more.

(Another Embodiment of Manufacturing Method) In the above embodiment, the case where co-extrusion is performed by using an apparatus as shown in FIG. 1A has been exemplified, but the core material moves in the axial direction while rotating. By using the apparatus, the co-extruded strip may be spirally wound around a core material to form a tubular body. In this case, since the length of the core material limits the length of one continuous production, one to several productions may be produced in one continuous process.

In the above-described embodiment, an example has been described in which coextrusion is performed while maintaining the extrusion speed and the width of the strip in the coextrusion substantially constant, and the core material is spirally wound at a substantially constant pitch. However, the manufacturing method of the present invention is not limited to the case where the pitch is substantially constant. That is, the tubular body may be formed by spirally winding the core material at different pitches according to the winding speed and the feeding speed of the core material in accordance with the change in the extrusion speed and the width of the band.

In the present invention, reinforcement by long fibers may be further performed. In this case, a rotating body provided with a plurality of bobbins for feeding long fibers is provided around the downstream side of the extruder A, and the tubular body 14 is provided. The reinforcing angle of the long fiber can be adjusted by controlling the rotation speed of the rotator according to the rotation angular speed of the rotation. When reinforcing fibers cross in a biased manner,
It is sufficient to provide two rotating bodies that rotate in opposite directions, and control the rotation speed of each rotating body in consideration of the angular velocity of rotation of the tubular body 14.

In the above case, the surface layer is usually coated on the outside of the long fiber (see FIG. 6). However, an extruder similar to the above is provided downstream of the rotating body so that the soft resin or the like is provided. It may be extruded in a belt shape. Also, as for the surface layer, two or more materials may be co-extruded in the same manner as described above, in which case, a hard thermoplastic resin is laminated above the hard thermoplastic resin,
It is preferable that the layer is also laminated above the polyolefin-based thermoplastic elastomer. By making the pitch of both layers substantially the same, such a laminated structure can be obtained.

(Materials Used) As the two or more materials having different rigidities used in the present invention, any materials can be used as long as they can be co-extruded as described above and can provide a certain degree of joining strength of each material. Two or more (i.e., three or more) materials having different rigidities are appropriately selected from various thermoplastic resins, thermoplastic elastomers, rubbers, thermosetting resins, and the like. Therefore, for the co-extruded raw material, the thermoplastic resin and the thermoplastic elastomer are directly heated and melt-extruded, and for the rubber and the thermosetting resin, the unreacted raw materials of the unvulcanized rubber and the thermosetting resin are co-extruded. Extruded. It is preferable that these raw materials have some shape retention properties even at the extrusion temperature and solidify to some extent after cooling, in relation to the above-mentioned production method. If unreacted raw materials such as unvulcanized rubber and thermosetting resin are used,
A cross-linking step and a curing step are performed after the formation of the tubular body.

As a combination of the above materials, a combination of thermoplastic materials, a combination of reaction curable materials, or a combination of both can be considered, but a combination of a hard thermoplastic resin and a thermoplastic elastomer is preferable. Examples of the hard thermoplastic resin include polyolefin, other polyvinyl resins, and polyester resins, and examples of the thermoplastic elastomer include polyolefin-based thermoplastic elastomers, polystyrene-based thermoplastic elastomers, and polydiene-based thermoplastic elastomers. . Among them, a combination of a hard polyolefin and a polyolefin-based thermoplastic elastomer is particularly preferred. In addition, for flexible joints, it is preferable to consider the bonding strength with the hard resin pipe to be connected, and use the same or similar material as the hard resin pipe so as to easily perform heat fusion and the like. preferable.

The polyolefin-based thermoplastic elastomer (hereinafter referred to as “TPO”) is a blend containing a polyolefin such as polyethylene, polypropylene and polybutene as a hard segment and a rubber such as ethylene propylene (EPDM) as a soft segment. Body and the like. And, depending on the difference of the blending method, the simple blend type TPO, the implanted TP
O, dynamic vulcanization type TPO and the like are present, and usually have a blend structure in which a soft segment component is dispersed in a hard segment component.

Various types of such TPO are commercially available, such as Oleflex (manufactured by Nippon Polyolefin), Mirastomer (manufactured by Mitsui Chemicals), Sumitomo TPE (manufactured by Sumitomo Chemical), Santoprene (manufactured by AES Japan), and Rheostomer. (Manufactured by Riken Vinyl Industry), Actima (manufactured by Riken Vinyl Industry) and the like. The TPO is J
Those having an ISA hardness of 40 to 80 ° are preferred, and may be reinforced with short fibers or the like.

As the polyolefin, polyethylene,
Polypropylene, polybutene, etc., and TPO
It is preferable to use the same type of material as the TPO hard segment from the viewpoint of increasing the bonding strength with the TPO. In particular, when used as a flexible joint for polyethylene piping, the polyolefin is polyethylene or polypropylene,
Most preferably, the TPO hard segment is polyethylene and / or polypropylene and the soft segment is EPDM.

The long fibers optionally used include:
Fibers such as polyester, nylon, and polyolefin are exemplified, and polyolefin fibers are preferred from the viewpoint of ease of recycling. Also, as the material of the surface layer,
One or two or more materials having different stiffness as described above are used.

(Structure of Composite Flexible Tube, etc.) The composite flexible tube of the present invention is composed of two or more materials having different rigidities.
A composite flexible pipe in which at least one kind thereof is spirally arranged at a substantially constant pitch, characterized in that the constituent weight ratio of the material per pitch varies in the longitudinal direction. In this embodiment, as shown in FIG. 3, the component weight ratio for each pitch continuously changes in the longitudinal direction, and the component weight ratio for each pitch of the hard thermoplastic resin 1 is the smallest at the center of the tube. The one having a structure in which the rigid thermoplastic resin 1 which is the largest at the tube end and is near the tube end is joined in the longitudinal direction is illustrated.

In the example shown in FIG. 3, the constituent weight ratio of each pitch of the hard thermoplastic resin 1 is changed from 25/75 to 90/10, and the hard thermoplastic resin 1 is hard thermoplastic resin over 3 pitches at both ends. Resin 1 is joined in the longitudinal direction. The outer and inner peripheral surfaces have almost no irregularities, and the outer and inner diameters are substantially constant.

The composite flexible tube of the present invention has, for example, an outer diameter of 2 mm.
The thickness can be 0 to 300 mm, the thickness is 3 to 30 mm, and the length is 100 m or less, but it can be appropriately designed according to required characteristics. In that case, the design according to the conventional product can be performed by considering the constituent weight ratio of two or more types of materials in each part. However, the composite flexible pipe of the present invention reinforces a part where stress is easily concentrated. Can be locally increased, so that the length and the wall thickness of the composite flexible pipe can be made smaller than before.

The composite flexible pipe of the present invention can be used in applications other than flexible joints for connecting other hard resin pipes and the like, but is preferably used as a flexible joint as described above. In this case, a hard resin pipe (connecting pipe) may be joined to both ends of the composite flexible pipe, but the hard resin pipe is not provided, and the hard resin pipe is directly bonded by a fusion welding method such as an EF method or a bad joint method. It is more preferable to connect resin tubes and the like.

As shown in FIG. 4, the bad joint method is a method of fusing and joining such that both end surfaces of a flexible joint J abut between two hard resin pipes P1. That is, at least one end face of the hard resin pipe P1 or the flexible joint J is heated and melted, and then both end faces are pressed to perform pressure welding. At that time, it is preferable that both end faces are accurately cut at right angles to the axis. Among the composite flexible pipes of the present invention, in particular, those having a structure in which the hard thermoplastic resin near the pipe end is joined in the longitudinal direction, the hard thermoplastic resin is exposed over the entire circumference of the pipe end face. In such a bad joint method, the hard resin pipe P1 can be directly and firmly joined.

The EF (Electrofusion) method is
As shown in FIG. 5, in a state where the end of the hard resin pipe P1 and the end of the flexible joint J are fitted inside the EF joint P2 having an internal heating wire or the like, the outer peripheral surfaces thereof are joined to the EF joint P2. It is a method of fusing with the inner peripheral surface of That is, the end of the hard resin pipe P1 and the end of the flexible joint J are preliminarily cleaned, smoothed for cutting, etc., and then fitted inside the EF joint P2.
In this state, electricity is supplied to the EF joint P2, and the outer peripheral surface and the inner peripheral surface are fused and fused. Among the composite flexible pipes of the present invention, in particular, those having a structure in which the hard thermoplastic resin near the pipe end is joined in the longitudinal direction, the exposed amount of the hard thermoplastic resin on the outer peripheral surface near the pipe end becomes large. For,
In the EF method as described above, the EF joint P2 can be firmly joined without using a connection pipe, and the hard resin pipe P1 can be connected through the EF joint P2.

The composite flexible pipe of the present invention includes pipes for water distribution, water supply, drainage, etc. (buried pipes or internal pipes of buildings), including the use as flexible joints as described above, and the cooling and heating of air conditioning and sanitary facilities. It can be used for water pipes, gas supply pipes, protection pipes for communication lines and power cables, and the like.

(Another Embodiment of Composite Flexible Tube) In the above embodiment, an example in which reinforcement with long fibers is not used is shown. However, reinforcement with long fibers may be used together as shown in FIG. In that case, the fiber reinforcement layer 4 is formed on the outer periphery of the tubular body 14, and the surface layer 5 is further laminated as an outer layer. The fiber reinforcing layer 4 is usually formed of a fiber group in two directions such that the reinforcing fibers intersect in a biased manner (preferably, the reinforcing angle is closer to the static angle). By the reinforcement with such long fibers, the pressure resistance against the internal pressure can be further increased, which is more advantageous for pumping.

Further, in the above embodiment, the example in which the composite flexible tube is a straight tube is shown. However, as shown in FIG. 7, the central portion of the composite flexible tube may have a spherically expanded shape.
In this case, it can be manufactured by a method of expanding the inside by pressurizing the inside with air while heating the tubular body formed into a straight tube, or a method of applying pressure from the inside using a split mold. By adopting such a shape, the amount of absorbing expansion and contraction in the axial direction can be increased.

The composition weight ratio of the two or more materials in the present invention can be set within the range of 0/100 to 100/0, and is appropriately set according to the use of the composite flexible tube. . For example, a structure in which a portion made of only a hard material and a portion made of only a soft material are connected and integrated by an abrupt change in the composition weight ratio can be given.

[0062]

EXAMPLES Examples for confirming the effects of the present invention will be described below.

Example An extruder with a die capable of co-extrusion (cylinder diameter φ4
0, L / D = 25), and a band shape (height 8 mm × width 6 m)
m) and a soft material (thermoplastic elastomer, Nippon Polyolefin, Oleflex P132 (PP + PE + EPDM)) integrated with a hard material (high-density polyethylene, Asahi Kasei Kogyo, Suntech HD, B770).
Co-extruded at ℃. This was spirally wound around a core material moving in the axial direction while rotating to form a tubular body. At that time, the product was wound 50 times to obtain a product having a total length of 300 mm, and the constituent weight ratio per pitch of the hard material was the smallest at the center of the tube (25/75) and the largest at the tube end (90/1).
0), the co-extrusion ratio was changed.

Comparative Example A constant weight ratio (50/5) of the hard material for each pitch was used.
0) except that the total length is 300 mm.
Got the product.

Test Example The product obtained above was joined to a polyethylene pipe (Eslo Hyper PE, manufactured by Sekisui Chemical Co., Ltd.) using a commercially available EF joint (manufactured by Sekisui Chemical Co., Ltd.) under the optimum energizing conditions.
This was subjected to an elongation fatigue test 100,000 times.
While the elongation (for the soft material) was allowed, the limit of the product of the comparative example was 10%. Above that, breakage occurred at the joint with the EF joint.

When the bending fatigue test and the eccentric fatigue test were performed in the same manner, the product of the comparative example broke at the joint with a small displacement as compared with the example, similarly to the above. Furthermore,
The same result as in the case of the EF method was also obtained for the case where the polyethylene pipe was directly joined by the bad joint method.

In any of the tests, the products of the examples did not break at portions other than the joints.

[Brief description of the drawings]

FIG. 1A is a front view illustrating an example of a manufacturing apparatus used in the present invention, and FIG. 1B is a cross-sectional view illustrating an example of a main part thereof.

FIG. 2 is a cross-sectional view showing an example of the shape of a strip.

FIG. 3 is a front view showing an example of a composite flexible tube according to the present invention in a partial cross section.

FIG. 4 is a front view showing a partial cross section of an example of a composite flexible pipe joined by a bad joint method.

FIG. 5 is a front view showing a partial cross section of an example of a composite flexible pipe joined by the EF method.

FIG. 6 is a front view showing a partial cross section of an example of a composite flexible tube according to another embodiment.

FIG. 7 is a front view showing an example of a composite flexible tube according to another embodiment in a partial cross section.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hard thermoplastic resin (hard material) 2 Thermoplastic elastomer (soft material) 3 Strip 14 Tubular body A Extruder B Core material

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Shizuo Yokobori 1-17-18 Edobori, Nishi-ku, Osaka-shi, Osaka F-term (reference) 3H111 AA02 BA15 BA25 CA03 CA07 CA53 CB02 CB21 EA04

Claims (9)

[Claims] 1. A composite flexible pipe composed of two or more materials having different stiffnesses, at least one of which is helically arranged at a substantially constant pitch, wherein a constituent weight ratio of the material for each pitch is reduced. A flexible tube having a longitudinally varying portion. 2. The composite flexible tube according to claim 1, wherein the constituent weight ratio for each pitch changes continuously in the longitudinal direction. 3. The composite flexible tube according to claim 1, wherein said material is composed of a hard thermoplastic resin and a thermoplastic elastomer. 4. The composite flexible tube according to claim 3, wherein said hard thermoplastic resin is a hard polyolefin, and said thermoplastic elastomer is a polyolefin-based thermoplastic elastomer. 5. The composite flexible pipe according to claim 3, wherein the constituent weight ratio of the hard thermoplastic resin per pitch is smallest at the center of the pipe and largest at the end of the pipe. 6. The composite flexible pipe according to claim 5, wherein the rigid thermoplastic resin near the pipe end has a structure joined in a longitudinal direction. 7. A method for producing a composite flexible pipe, comprising a step of spirally winding a core material to form a tubular body while co-extruding two or more kinds of materials having different rigidities into a strip shape, A method for producing a composite flexible tube, wherein coextrusion is performed while changing the constituent weight ratio. 8. The method for producing a composite flexible tube according to claim 7, wherein the co-extrusion is performed while maintaining the extrusion speed of the co-extrusion and the external shape of the extrusion cross section substantially constant. 9. The method according to claim 7, wherein the material comprises a hard thermoplastic resin and a thermoplastic elastomer.