JP2021156305A - Resin pipe and method of producing the same - Google Patents

Abstract

To provide a resin pipe capable of enhancing pressure resistance.SOLUTION: A resin pipe according to this invention includes a polyethylene-polyethylene fiber composite layer containing polyethylene and polyethylene fiber. The polyethylene fiber has a degree of crystallization of 95% or more, and has molecules orientated in one direction. The polyethylene fiber is spirally arranged along an axial direction of the resin pipe.SELECTED DRAWING: Figure 1

Description

The present invention relates to a resin tube containing polyethylene and a method for producing the above resin tube.

High-pressure water flows through the fire extinguishing pipe that connects the water tank and the fire hydrant, the fire extinguishing pipe that connects the water tank and the sprinkler, and the plant piping installed in the factory. Therefore, pipes such as fire extinguishing pipes and plant pipes need to have high pressure resistance.

The following Patent Document 1 has an inner pipe made of resin, a reinforcing layer provided on the outer peripheral side of the inner pipe, and a protective layer provided on the outer peripheral side of the reinforcing layer, and the protective layer has a back surface. A resin pipe formed by wrapping a resin tape having an adhesive layer around the outer peripheral side of the reinforcing layer is disclosed.

Patent Document 2 below discloses a multi-layer pipe including at least the first layer, the second layer, and the third layer in the direction from the axis to the outer periphery. In this multilayer pipe, the first layer and the third layer are resin layers composed mainly of a polyolefin resin. In the multilayer pipe, the second layer is a fiber-reinforced resin layer containing a polyolefin resin and glass fibers, and the glass fibers are oriented in a direction along the outer periphery of the first layer.

Japanese Unexamined Patent Publication No. 2011-179626 Japanese Unexamined Patent Publication No. 2016-196914

Although the resin pipes described in Patent Documents 1 and 2 can increase the pressure resistance to some extent, the pressure resistance may not be sufficient. Further, since the resin pipe described in Patent Document 1 is wound with a resin tape, it is necessary to peel off the resin tape when connecting the resin pipes to each other, which is inferior in workability at the construction site.

An object of the present invention is to provide a resin tube capable of increasing pressure resistance. Another object of the present invention is to provide a method for producing the above resin tube.

According to a broad aspect of the present invention, the resin tube is provided with a polyethylene-polyethylene fiber composite layer containing polyethylene and polyethylene fibers, and the polyethylene fibers have a crystallinity of 95% or more and the molecules are contained. Provided is a polyethylene tube which is a polyethylene fiber oriented in one direction and in which the polyethylene fiber is spirally arranged along the axial direction of the resin tube.

In a particular aspect of the resin tube according to the present invention, the polyethylene-polyethylene fiber composite layer is the outermost layer of the resin tube.

In a specific aspect of the resin tube according to the present invention, the average value of the inclination angles of the polyethylene fibers from the axial direction to the circumferential direction of the resin tube is 40 degrees or more and 80 degrees or less.

In a specific aspect of the resin tube according to the present invention, the polyethylene fiber is a polyethylene fiber made into a twisted yarn.

In a specific aspect of the resin pipe according to the present invention, the average diameter of the twisted yarns is 0.15 mm or more, and the number of twisted yarns arranged per circumference of the resin pipe is 720 or more.

According to a broad aspect of the present invention, in the above-described method for manufacturing a resin tube, a step of extruding a tubular body in which polyethylene is present on the outer surface from a mold and a step of extruding the tubular body from the mold and the outside of the tubular body extruded from the mold. A resin tube comprising a step of spirally arranging the polyethylene fibers on the surface and a step of cooling the tubular body on which the polyethylene fibers are arranged to obtain a resin tube having the polyethylene-polyethylene fiber composite layer. Manufacturing method is provided.

According to a broad aspect of the present invention, in the method for producing a resin tube described above, a step of extruding a tubular body having polyethylene on the outer surface from a first water tank and a tubular body extruded from the first water tank. A step of heating the outermost layer of the above to obtain the outermost layer in a molten state, a step of spirally arranging the polyethylene fibers on the outer surface of the outermost layer in a molten state, and the step of arranging the polyethylene fibers. Provided is a method for producing a resin tube, which comprises a step of cooling the tubular body in a second water tank to obtain a resin tube provided with the polyethylene-polyethylene fiber composite layer.

The resin tube according to the present invention includes a polyethylene-polyethylene fiber composite layer containing polyethylene and polyethylene fibers. In the resin tube according to the present invention, the polyethylene fiber is a polyethylene fiber having a crystallinity of 95% or more and having molecules oriented in one direction. In the resin tube according to the present invention, the polyethylene fibers are spirally arranged along the axial direction of the resin tube. Since the resin tube according to the present invention has the above configuration, the pressure resistance can be improved.

1 (a), 1 (b), 1 (c) and 1 (d) are views showing a resin tube according to a first embodiment of the present invention. 2 (a) and 2 (b) are views showing a resin tube according to a second embodiment of the present invention. 3 (a) and 3 (b) are views showing a resin tube according to a third embodiment of the present invention. 4 (a) and 4 (b) are views showing a resin tube according to a fourth embodiment of the present invention. FIG. 5 is a diagram for explaining the inclination angle of the polyethylene fiber. FIG. 6 is a diagram for explaining a method for manufacturing a resin tube according to the first embodiment of the present invention. FIG. 7 is a diagram for explaining a method for manufacturing a resin tube according to a second embodiment of the present invention.

Hereinafter, the present invention will be described in detail.

(Resin tube)
The resin tube according to the present invention includes a polyethylene-polyethylene fiber composite layer containing polyethylene and polyethylene fibers. In the resin tube according to the present invention, the polyethylene fiber is a polyethylene fiber having a crystallinity of 95% or more and having molecules oriented in one direction. In the resin tube according to the present invention, the polyethylene fibers are spirally arranged along the axial direction of the resin tube.

Since the resin tube according to the present invention has the above configuration, the pressure resistance can be improved.

The resin tube may have a structure of one layer or may have a structure of two or more layers. The resin tube may have a two-layer structure, a three-layer structure, or a three-layer or more structure. When the resin tube has a one-layer structure, the resin tube includes only a polyethylene-polyethylene fiber composite layer.

From the viewpoint of further increasing the pressure resistance and easily manufacturing the resin tube, the polyethylene-polyethylene fiber composite layer is preferably the outermost layer of the resin tube.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. In the drawings below, the size, thickness, shape, etc. may differ from the actual size, thickness, shape, etc. for convenience of illustration.

1 (a), 1 (b), 1 (c) and 1 (d) are views showing a resin tube according to a first embodiment of the present invention. FIG. 1 (b) is a cross-sectional view taken along the line I-I of FIG. 1 (a). FIG. 1 (c) is a diagram along line II-II of FIG. 1 (a). FIG. 1A is a side sectional view. FIG. 1B is a cross-sectional view of a portion where polyethylene fibers are arranged. FIG. 1 (c) is a plan sectional view. FIG. 1D is an enlarged view of a portion surrounded by a dotted line in FIG. 1C.

The resin tube 11 shown in FIG. 1 includes a polyethylene-polyethylene fiber composite layer 1 (first layer), a second layer 2, and a third layer 3. The resin tube 11 is a multi-layer tube having a three-layer structure.

The polyethylene-polyethylene fiber composite layer 1 is arranged on the outer surface of the second layer 2 and is laminated. The third layer 3 is arranged on the inner surface of the second layer 2 and is laminated. The polyethylene-polyethylene fiber composite layer 1 is the outermost layer, the second layer 2 is the intermediate layer, and the third layer 3 is the innermost layer. The polyethylene-polyethylene fiber composite layer 1 is the outermost layer and the surface layer. The third layer 3 is the innermost layer and is a surface layer. The polyethylene-polyethylene fiber composite layer 1, the second layer 2, and the third layer 3 are tubular, respectively.

The polyethylene-polyethylene fiber composite layer 1 contains polyethylene and polyethylene fibers 5 (however, for convenience of illustration, polyethylene fibers are not shown in FIGS. 1A and 1C). The polyethylene fiber 5 is a polyethylene fiber that has been twisted.

The polyethylene fiber 5 and polyethylene are integrated. The polyethylene fiber 5 and polyethylene are fused. The polyethylene fiber 5 is embedded in the polyethylene-polyethylene fiber composite layer 1.

The polyethylene fibers 5 are spirally arranged along the axial direction X of the resin tube 11.

2 (a) and 2 (b) are views showing a resin tube according to a second embodiment of the present invention. FIG. 2A is a plan sectional view. FIG. 2B is an enlarged view of the portion surrounded by the dotted line in FIG. 2A.

The resin tube 11A shown in FIG. 2 has a polyethylene-polyethylene fiber composite layer 1A (first layer). The resin tube 11A is a single-layer tube having a one-layer structure.

The polyethylene-polyethylene fiber composite layer 1A contains the polyethylene fiber 5 (however, for convenience of illustration, the polyethylene fiber is not shown in FIG. 2A). The polyethylene fibers 5 are spirally arranged along the axial direction of the resin pipe 11A.

The polyethylene-polyethylene fiber composite layer 1A has a region R1 in which the polyethylene fibers 5 are present and a region R2 in which the polyethylene fibers 5 are not present in the thickness direction. The polyethylene-polyethylene fiber composite layer 1A has a region R1 on the outside and a region R2 on the inside. In the polyethylene-polyethylene fiber composite layer 1A, the polyethylene fiber 5 is present on the outer surface portion.

3 (a) and 3 (b) are views showing a resin tube according to a third embodiment of the present invention. FIG. 3A is a plan sectional view. FIG. 3B is an enlarged view of the portion surrounded by the dotted line in FIG. 3A.

The resin tube 11B shown in FIG. 3 includes a polyethylene-polyethylene fiber composite layer 1B (first layer), a second layer 2B, and a third layer 3B. The resin tube 11B is a multi-layer tube having a three-layer structure. The position where the polyethylene fiber 5 is arranged is different between the resin tube 11 shown in FIG. 1 and the resin tube 11B shown in FIG. 3 in the thickness direction of the polyethylene-polyethylene fiber composite layer.

The polyethylene-polyethylene fiber composite layer 1B contains the polyethylene fiber 5 (however, for convenience of illustration, the polyethylene fiber is not shown in FIG. 3A). The polyethylene fibers 5 are spirally arranged along the axial direction of the resin pipe 11B.

The polyethylene-polyethylene fiber composite layer 1B has a region R1 in which the polyethylene fibers 5 are present and a region R2 in which the polyethylene fibers 5 are not present in the thickness direction. The polyethylene-polyethylene fiber composite layer 1B has a region R1 on the outside and a region R2 on the inside.

The polyethylene fiber 5 has a portion exposed from the polyethylene-polyethylene fiber composite layer 1B. The polyethylene fiber 5 has a portion exposed from the outer surface of the resin tube 11B. The outer surface of the resin tube 11B has irregularities derived from the polyethylene fiber 5.

4 (a) and 4 (b) are views showing a resin tube according to a fourth embodiment of the present invention. FIG. 4A is a plan sectional view. FIG. 4B is an enlarged view of the portion surrounded by the dotted line in FIG. 4A.

The resin tube 11C shown in FIG. 4 has a polyethylene-polyethylene fiber composite layer 1C (first layer). The resin tube 11C is a single-layer tube having a one-layer structure.

The polyethylene-polyethylene fiber composite layer 1C contains the polyethylene fiber 5 (however, for convenience of illustration, the polyethylene fiber is not shown in FIG. 4A). The polyethylene fibers 5 are spirally arranged along the axial direction of the resin pipe 11C.

The polyethylene-polyethylene fiber composite layer 1C has a region R1 in which the polyethylene fibers 5 are present and a region R2 in which the polyethylene fibers 5 are not present in the thickness direction. The polyethylene-polyethylene fiber composite layer 1C has a region R1 on the outside and a region R2 on the inside.

The polyethylene fiber 5 has a portion exposed from the polyethylene-polyethylene fiber composite layer 1C. The polyethylene fiber 5 has a portion exposed from the outer surface of the resin tube 11C. The outer surface of the resin tube 11C has irregularities derived from the polyethylene fiber 5.

As shown in FIGS. 2 to 4, the resin tube according to the present invention may have a region in which polyethylene fibers are present and a region in which polyethylene fibers are not present in the thickness direction of the polyethylene-polyethylene fiber composite layer.

When the thickness of the polyethylene-polyethylene fiber composite layer is T, it is preferable that at least polyethylene fibers are present in a region of 0.5 T from the outside to the inside of the polyethylene-polyethylene fiber composite layer, preferably 0.3 T. More preferably, at least polyethylene fibers are present in the region. Further, it is more preferable that at least the polyethylene fiber is present in the region of 0.2 T from the outside to the inside of the polyethylene-polyethylene fiber composite layer, and it is particularly preferable that at least the polyethylene fiber is present in the region of 0.1 T.

From the inside to the outside of the polyethylene-polyethylene fiber composite layer, the polyethylene fiber may or may not be present in the region of 0.2 T. Further, the polyethylene fiber may or may not be present in the region of 0.1 T from the inside to the outside of the polyethylene-polyethylene fiber composite layer.

The outer surface of the resin tube may or may not have irregularities derived from the polyethylene fibers. The polyethylene fiber may or may not be embedded in the polyethylene-polyethylene fiber composite layer. The polyethylene fiber may or may not be exposed from the outer surface of the resin tube.

When the polyethylene fiber is exposed from the outer surface of the resin tube, the surface area of the portion where the polyethylene fiber is exposed from the outer surface of the resin tube is 10% or more in 100% of the surface area of the polyethylene fiber. It may be 50% or less, or 40% or less.

The polyethylene fibers may or may not be visually identifiable when the resin tube is viewed in a plan view from the outside in the axial direction. The polyethylene fibers may or may not be visually identifiable when the resin tube is viewed from the outside in the circumferential direction.

FIG. 5 is a diagram for explaining the inclination angle of the polyethylene fiber. FIG. 5 shows the polyethylene fiber 5. In FIG. 5, X is the axial direction of the resin tube, Y is the circumferential direction of the resin tube, and L is the spiral direction of the polyethylene fibers in the resin tube. The inclination angle θ of the polyethylene fiber is an angle at which the polyethylene fiber is inclined from the axial direction X of the resin tube to the circumferential direction Y. The inclination angle θ of the polyethylene fiber means the smaller angle of the straight line in the axial direction X and the straight line in the spiral direction L. Therefore, the minimum value of the inclination angle θ of the polyethylene fiber is 0 degrees, and the maximum value is 90 degrees.

When the inclination angle θ of the polyethylene fiber is 0 degree, the spiral direction of the polyethylene fiber coincides with the axial direction of the resin tube. When the inclination angle θ of the polyethylene fiber is 90 degrees, the spiral direction of the polyethylene fiber coincides with the circumferential direction of the resin tube.

From the viewpoint of further increasing the pressure resistance, the average value of the inclination angle θ of the polyethylene fibers from the axial direction to the circumferential direction of the resin tube is preferably 40 degrees or more, more preferably 60 degrees or more, preferably 60 degrees or more. It is 80 degrees or less, more preferably 75 degrees or less.

The average value of the inclination angle θ can be obtained by measuring the inclination angle θ at three or more positions separated from each other in the circumferential direction and calculating the average value.

<Polyethylene-polyethylene fiber composite layer>
resin:
The polyethylene-polyethylene fiber composite layer contains polyethylene. The polyethylene-polyethylene fiber composite layer may or may not contain a resin other than polyethylene. Only one type of polyethylene may be used, or two or more types may be used in combination. As the resin other than polyethylene, only one kind may be used, or two or more kinds may be used in combination.

The polyethylene may be low-density polyethylene, linear low-density polyethylene, high-density polyethylene, or anti-heat-resistant polyethylene (PE-RT). Further, the polyethylene may be a homopolymer of ethylene or a copolymer of a monomer containing ethylene. When the polyethylene is a copolymer of a monomer containing ethylene, the polyethylene may be a random copolymer or a block copolymer.

It is preferable that 50% by weight or more (preferably 80% by weight or more, more preferably 90% by weight or more) of the monomers constituting the polyethylene contained in the polyethylene-polyethylene fiber composite layer is ethylene.

From the viewpoint of increasing the pressure resistance, the polyethylene contained in the polyethylene-polyethylene fiber composite layer is preferably high-density polyethylene. High-density polyethylene means polyethylene having a density of 0.945 g / cm ³ or more. Polyethylene - density polyethylene contained in the polyethylene fiber composite layer is preferably 0.942 g / cm ³ or more, more preferably 0.945 g / cm ³ or more, further preferably 0.949 g / cm ³ or more.

The content of the polyethylene (content of polyethylene excluding the polyethylene constituting the polyethylene fiber) in 100% by weight of the polyethylene-polyethylene fiber composite layer is preferably 90% by weight or more, more preferably 95% by weight or more, still more preferably. Is 97% by weight or more, preferably 100% by weight or less. When the content of the polyethylene is at least the above lower limit, the coefficient of linear expansion can be further reduced and the pressure resistance can be further increased.

Polyethylene fiber:
The polyethylene-polyethylene fiber composite layer contains polyethylene fibers. Only one type of the polyethylene fiber may be used, or two or more types may be used in combination.

From the viewpoint of reducing the coefficient of linear expansion, the crystallinity of the polyethylene fiber is 95% or more.

The crystallinity of the polyethylene fiber can be measured by performing DSC measurement under the following conditions using a differential scanning calorimeter (for example, "DSC7020" manufactured by Seiko Instruments Inc.).

-Measurement range: 20 ° C to 220 ° C, elevating temperature rate: 10 ° C / min, nitrogen flow: 50 ml / min
-Sample container: Aluminum pan sealed container-PE perfect crystal The degree of crystallinity is calculated with the heat of fusion as 286.7 (J / g).

From the viewpoint of reducing the coefficient of linear expansion, the polyethylene fiber is a polyethylene fiber in which molecules are oriented in one direction. The polyethylene fiber is a highly oriented polyethylene fiber.

From the viewpoint of further reducing the coefficient of linear expansion and further increasing the pressure resistance, the polyethylene fiber is preferably an ultra-high molecular weight polyethylene fiber.

The weight average molecular weight of the polyethylene constituting the polyethylene fiber is preferably 700,000 or more, more preferably 900,000 or more. When the weight average molecular weight is at least the above lower limit, the coefficient of linear expansion can be further reduced and the pressure resistance can be further increased.

The weight average molecular weight of the polyethylene constituting the polyethylene fiber indicates the polystyrene-equivalent weight average molecular weight measured by gel permeation chromatography (GPC).

The elastic modulus of the polyethylene fiber at 23 ° C. is preferably 80 GPa or more, more preferably 120 GPa or more. When the elastic modulus is at least the above lower limit, the coefficient of linear expansion can be further reduced, and the pressure resistance can be further increased.

The elastic modulus of the polyethylene fiber at 23 ° C. can be measured by a tensile test of the polyethylene fiber.

A plurality of the polyethylene fibers may be collectively formed into twisted yarns and may be contained in the polyethylene-polyethylene fiber composite layer. The polyethylene fiber may be a polyethylene fiber made of twisted yarn.

The number of polyethylene fibers constituting one twisted yarn is preferably 2 or more, preferably 10 or less, and more preferably 6 or less.

The average fiber diameter of the polyethylene fibers is preferably 0.03 mm or more, more preferably 0.05 mm or more, preferably 0.5 mm or less, and more preferably 0.3 mm or less. When the average fiber diameter of the polyethylene fiber is not less than the above lower limit and not more than the above upper limit, the coefficient of linear expansion can be further reduced and the pressure resistance can be further increased.

The average fiber diameter of the polyethylene fibers is obtained by determining the fiber diameter of one polyethylene fiber and averaging the fiber diameters of a plurality of polyethylene fibers.

The average diameter of the twisted yarn is preferably 0.10 mm or more, preferably 0.50 mm or less, and more preferably 0.30 mm or less. When the average diameter of the twisted yarn is at least the above lower limit and at least the above upper limit, the coefficient of linear expansion can be further reduced and the pressure resistance can be further increased.

The average diameter of the twisted yarns is obtained by obtaining the diameter of one twisted yarn and averaging the diameters of a plurality of twisted yarns.

The number of twisted yarns arranged per 10 mm of the circumferential length of the resin pipe is preferably 5 or more, more preferably 20 or more, preferably 30 or less, and more preferably 25 or less. When the number is equal to or higher than the lower limit and lower than the upper limit, the coefficient of linear expansion can be further reduced and the pressure resistance can be further increased.

The number of twisted yarns arranged per circumference of the resin tube is preferably 360 or more, more preferably 720 or more, further preferably 800 or more, preferably 2000 or less, and more preferably 1500 or less. be. When the number is equal to or higher than the lower limit and lower than the upper limit, the coefficient of linear expansion can be further reduced and the pressure resistance can be further increased.

The twisted yarns are preferably arranged at equal intervals in the circumferential direction of the resin tube.

<Layer other than polyethylene-polyethylene fiber composite layer>
The resin tube may or may not include a layer other than the polyethylene-polyethylene fiber composite layer.

resin:
From the viewpoint of increasing the pressure resistance, the layer other than the polyethylene-polyethylene fiber composite layer preferably contains a polyolefin resin or a vinyl chloride resin, and more preferably contains a polyolefin resin.

Examples of the polyolefin resin include polyethylene, polypropylene, polybutene, ethylene-vinyl acetate copolymer, ethylene-α-olefin copolymer and the like. Only one type of the polyolefin resin may be used, or two or more types may be used in combination.

From the viewpoint of further increasing the pressure resistance, the polyolefin resin is preferably polyethylene or polypropylene, and more preferably polyethylene.

fiber:
Layers other than the polyethylene-polyethylene fiber composite layer may contain fibers. Only one type of the fiber may be used, or two or more types may be used in combination.

The fiber may be an inorganic fiber or an organic fiber.

Examples of the inorganic fiber include glass fiber, carbon fiber, silicon / titanium / carbon composite fiber, boron fiber, metal fiber and the like.

Examples of the organic fiber include aramid fiber, vinylon fiber, polyester fiber, polyamide fiber and the like.

In a resin tube in which inorganic fibers such as glass fibers are used, there is a risk that components eluted from the inorganic fibers are mixed in the liquid flowing inside. Therefore, when the resin pipe is used as a pipe through which a liquid for drinking water such as a water supply / hot water supply pipe is passed, the resin pipe preferably does not contain inorganic fibers and does not contain glass fibers. Is preferable. However, when the water supply / hot water supply pipe or the like is not used as a pipe through which drinking water is passed, the resin pipe may contain inorganic fibers or may contain glass fibers.

The average fiber length of the fibers is preferably 100 μm or more, more preferably 200 μm or more, still more preferably 400 μm or more, preferably 1500 μm or less, more preferably 1000 μm or less, still more preferably 800 μm or less. When the average fiber length of the fibers is not less than the above lower limit and not more than the above upper limit, the pressure resistance of the resin tube can be further increased.

The average fiber length of the above fibers is obtained by obtaining the fiber length of one fiber and averaging the fiber lengths of a plurality of fibers. The fiber length is the distance between one end and the other end of the fiber when the fiber is straightened.

The average fiber diameter of the fibers is preferably 5 μm or more, more preferably 7 μm or more, still more preferably 9 μm or more, preferably 17 μm or less, more preferably 13 μm or less, still more preferably 11 μm or less. When the average fiber diameter of the fibers is not less than the above lower limit and not more than the above upper limit, the pressure resistance of the resin tube can be further increased.

The average fiber diameter of the above fibers is obtained by determining the fiber diameter of one fiber and averaging the fiber diameters of a plurality of fibers.

In 100% by weight of the layer containing the fibers, the content of the fibers is preferably 5% by weight or more, more preferably 10% by weight or more, preferably 30% by weight or less, and more preferably 25% by weight or less. When the fiber content is at least the above lower limit and at least the above upper limit, the pressure resistance of the resin tube can be further increased.

<Other ingredients>
The resin tube may contain various additives, if necessary. Examples of the above additives include compatibilizers, stabilizers, stabilizers, lubricants, processing aids, impact modifiers, heat resistance improvers, antioxidants, UV absorbers, light stabilizers, fillers, pigments and Examples include plasticizers. It is particularly preferable to use a compatibilizer in the resin tube. Only one kind of the above-mentioned additive may be used, or two or more kinds thereof may be used in combination.

The compatibilizer is not particularly limited, and examples thereof include maleic acid-modified polyolefin, silane-modified polyolefin, and chlorinated polyolefin. These compatibilizers are not included in the polyolefin resin. Only one kind of the compatibilizer may be used, or two or more kinds thereof may be used in combination.

The stabilizer is not particularly limited, and examples thereof include a heat stabilizer and a heat stabilization aid. The heat stabilizer is not particularly limited, and examples thereof include an organic tin-based stabilizer, a lead-based stabilizer, a calcium-zinc-based stabilizer, a barium-zinc-based stabilizer, and a barium-cadmium-based stabilizer. Examples of the organic tin stabilizer include dibutyl tin mercapto, dioctyl tin mercapto, dimethyl tin mercapto, dibutyl tin mercapto, dibutyl tin malate, dibutyl tin malate polymer, dioctyl tin malate, dioctyl tin malate polymer, dibutyl tin laurate, and the like. Examples thereof include dibutyltin laurate polymer. Only one kind of the above stabilizer may be used, or two or more kinds may be used in combination.

The heat stabilizing aid is not particularly limited, and examples thereof include epoxidized soybean oil, phosphoric acid ester, polyol, hydrotalcite, and zeolite. As the heat stabilization aid, only one kind may be used, or two or more kinds may be used in combination.

The lubricant is not particularly limited, and examples thereof include an internal lubricant and an external lubricant. The internal lubricant is used for the purpose of lowering the flow viscosity of the molten resin during molding and preventing frictional heat generation. The internal lubricant is not particularly limited, and examples thereof include butyl stearate, lauryl alcohol, stearyl alcohol, epoxy soybean oil, glycerin monostearate, stearic acid, and bisamide. The external lubricant is used for the purpose of enhancing the sliding effect between the molten resin and the metal surface during the molding process. The external lubricant is not particularly limited, and examples thereof include paraffin wax, polyolefin wax, ester wax, and montanic acid wax. Only one kind of the above-mentioned lubricant may be used, or two or more kinds may be used in combination.

The processing aid is not particularly limited, and examples thereof include an acrylic processing aid. Examples of the acrylic processing aid include alkyl acrylate-alkyl methacrylate copolymers having a weight average molecular weight of 100,000 to 2 million, and specifically, n-butyl acrylate-methyl methacrylate copolymer and n-butyl acrylate-methyl methacrylate copolymer. Examples thereof include 2-ethylhexyl acrylate-methyl methacrylate-butyl methacrylate copolymer. As the processing aid, only one kind may be used, or two or more kinds may be used in combination.

The impact modifier is not particularly limited, and examples thereof include methyl methacrylate-butadiene-styrene copolymer (MBS), chlorinated polyethylene, and acrylic rubber. Only one type of the impact modifier may be used, or two or more types may be used in combination.

The heat resistance improving agent is not particularly limited, and examples thereof include α-methylstyrene-based resins and N-phenylmaleimide-based resins. Only one kind of the heat resistance improving agent may be used, or two or more kinds thereof may be used in combination.

The antioxidant is not particularly limited, and examples thereof include phenolic antioxidants. Only one kind of the above-mentioned antioxidant may be used, or two or more kinds may be used in combination.

The ultraviolet absorber is not particularly limited, and examples thereof include a salicylate ester-based ultraviolet absorber, a benzophenone-based ultraviolet absorber, a benzotriazole-based ultraviolet absorber, and a cyanoacrylate-based ultraviolet absorber. Only one kind of the above-mentioned ultraviolet absorber may be used, or two or more kinds may be used in combination.

The light stabilizer is not particularly limited, and examples thereof include hindered amine-based light stabilizers. Only one kind of the above-mentioned light stabilizer may be used, or two or more kinds thereof may be used in combination.

The filler is not particularly limited, and examples thereof include calcium carbonate and talc. Only one kind of the filler may be used, or two or more kinds thereof may be used in combination.

The pigment is not particularly limited, and examples thereof include organic pigments and inorganic pigments. Examples of the organic pigments include azo-based organic pigments, phthalocyanine-based organic pigments, slene-based organic pigments, and dye lake-based organic pigments. Examples of the inorganic pigments include oxide-based inorganic pigments, molybdenum chromate-based inorganic pigments, sulfide / selenium-based inorganic pigments, and ferrosinide-based inorganic pigments. Only one kind of the above pigment may be used, or two or more kinds may be used in combination.

The plasticizer may be added for the purpose of improving processability at the time of molding. Since the heat resistance of the molded product may decrease due to the addition of the plasticizer, it is preferable that the amount of the plasticizer added is small. The plasticizer is not particularly limited, and examples thereof include dibutyl phthalate, di-2-ethylhexyl phthalate, and di-2-ethylhexyl adipate. Only one type of the above-mentioned plasticizer may be used, or two or more types may be used in combination.

(Other details of resin tube)
The SDR (outer diameter of the resin tube / thickness of the resin tube) of the resin tube is preferably 8 or more, more preferably 10 or more, further preferably 11 or more, preferably 15 or less, and more preferably 13.5 or less. .. When the SDR is at least the above lower limit and at least the above upper limit, the pressure resistance can be increased, the flow rate of the liquid flowing inside can be increased, and the resin tube can be made lighter.

(Manufacturing method of resin tube)
The resin tube described above can be manufactured by, for example, the following manufacturing method (1) or manufacturing method (2).

The manufacturing method (1) includes the following steps.

Step (1A): A step of extruding a tubular body having polyethylene on the outer surface from a mold.

Step (1B): A step of spirally arranging the polyethylene fibers on the outer surface of the tubular body extruded from the mold.

Step (1C): A step of cooling the tubular body on which the polyethylene fibers are arranged to obtain a resin tube provided with the polyethylene-polyethylene fiber composite layer.

FIG. 6 is a diagram for explaining a method for manufacturing a resin tube according to the first embodiment of the present invention. FIG. 6 is a diagram for explaining the manufacturing method (1). FIG. 6 is a diagram for explaining a method of manufacturing the resin tube 11A shown in FIG.

In the manufacturing method (1), a manufacturing apparatus including a mold 20, a bobbin 21, a tensioner 22, a water tank 23, a forming tube 24, and a rotary take-up machine is used.

The tubular body 11AX having polyethylene on the outer surface is extruded from the mold 20. Further, the tubular body 11AX is picked up at a constant linear speed using a pick-up machine. Tubular body 11AX is a parison. The tubular body 11AX is a single-layer tubular body containing polyethylene. The tubular body 11AX is not solidified and is in a molten state. In particular, the outer surface of the tubular body 11AX is not solidified and is in a molten state.

The set temperature of the outlet tip of the mold 20 is preferably 160 ° C. or higher, and preferably 220 ° C. or lower. Further, the temperature of the outer surface of the tubular body 11AX at the outlet tip of the mold 20 is preferably 170 ° C. or higher, and preferably 230 ° C. or lower.

A polyethylene fiber 5 as a twisted yarn is wound around the bobbin 21.

The twisted yarn of the polyethylene fiber 5 is spirally arranged on the outer surface of the tubular body 11AX extruded from the mold 20 from the bobbin 21 via the tensioner 22. A plurality of polyethylene fibers 5 having a constant tension from the bobbin 21 to the tensioner 22 are spirally arranged on the outer surface of the tubular body 11AX. The polyethylene fibers 5 can be arranged in a spiral shape by rotating the tubular body 11AX using a rotary take-up machine installed downstream of the water tank 23.

The number of polyethylene fibers to be arranged, the fiber diameter, and the like can be appropriately changed depending on the required coefficient of linear expansion and the thickness of the resin tube.

When the polyethylene fiber 5 is arranged on the outer surface of the tubular body 11AX, it is preferable to lower the temperature of the outer surface of the tubular body 11AX by a water film or cooling air. It is preferable to dispose the polyethylene fiber 5 on the outer surface of the tubular body 11AX after lowering the temperature of the outer surface of the tubular body 11AX. The temperature of the outer surface of the tubular body 11AX when the polyethylene fibers 5 are arranged is preferably 120 ° C. or higher, more preferably 130 ° C. or higher, preferably 160 ° C. or lower, and more preferably 150 ° C. or lower. When the temperature of the outer surface is equal to or higher than the above lower limit, polyethylene and polyethylene fibers can be satisfactorily integrated. When the temperature of the outer surface is not more than the above upper limit, shrinkage and cutting of the polyethylene fiber can be effectively suppressed.

The tubular body 11AX on which the polyethylene fibers 5 are arranged is shaped into a predetermined outer diameter by using the forming tube 24 installed on the inner surface of the water tank 23. Further, the tubular body 11AX is cooled in the water tank 23. In this way, the resin tube 11A provided with the polyethylene-polyethylene fiber composite layer can be obtained.

The manufacturing method (2) includes the following steps.

Step (2A): A step of extruding a tubular body having polyethylene on the outer surface from the first water tank.

Step (2B): A step of heating the outermost layer of the tubular body extruded from the first water tank to obtain the outermost layer in a molten state.

Step (2C): A step of spirally arranging the polyethylene fibers on the outer surface of the outermost layer in a molten state.

Step (2D): A step of cooling the tubular body on which the polyethylene fibers are arranged in a second water tank to obtain a resin tube provided with the polyethylene-polyethylene fiber composite layer.

FIG. 7 is a diagram for explaining a method for manufacturing a resin tube according to a second embodiment of the present invention. FIG. 7 is a diagram for explaining the manufacturing method (2). FIG. 7 is a diagram for explaining a method of manufacturing the resin tube 11 shown in FIG.

In the manufacturing method (2), the first water tank 33A, the forming tube 34A, the heating device 30, the bobbin 31, the tensioner 32, the second water tank 33B, the forming tube 34B, the pressing roll 35, and the rotation A manufacturing apparatus equipped with a pick-up machine is used.

A multi-layered tubular body (three-layered tubular body in FIG. 7) having polyethylene on the outer surface is extruded from the mold. The outermost layer of this tubular body contains polyethylene. In addition, this tubular body is picked up at a constant linear speed using a pick-up machine.

The tubular body extruded from the mold is shaped into a predetermined outer diameter using a forming tube 34A installed on the inner surface of the first water tank 33A. Further, the tubular body is cooled in the first water tank 33A.

The tubular body 11X having polyethylene on the outer surface is taken from the first water tank 33A.

The outermost layer of the tubular body 11X taken from the first water tank 33A is heated by using the heating device 30. By this operation, an outermost layer that is not solidified and is in a molten state can be obtained. The layers other than the outermost layer may be in a molten state or may not be in a molten state. The layers other than the outermost layer are preferably not in a molten state, and are preferably solidified.

Examples of the heating device include an IR heater and a hot air generator. The heating temperature of the heating device is appropriately set.

A polyethylene fiber 5 as a twisted yarn is wound around the bobbin 31.

The twisted yarn of the polyethylene fiber 5 is spirally arranged on the outer surface of the tubular body 11Y taken from the heating device 30 from the bobbin 31 via the tensioner 32. A plurality of polyethylene fibers 5 having a constant tension from the bobbin 31 to the tensioner 32 are spirally arranged on the outer surface of the tubular body 11Y. The polyethylene fibers 5 can be arranged in a spiral shape by rotating the tubular body 11Y using a rotary take-up machine installed downstream of the second water tank 33B.

The temperature of the outer surface of the tubular body 11Y when the polyethylene fiber 5 is arranged is preferably 120 ° C. or higher, more preferably 130 ° C. or higher, preferably 160 ° C. or lower, and more preferably 150 ° C. or lower. When the temperature of the outer surface is equal to or higher than the above lower limit, polyethylene and polyethylene fibers can be satisfactorily integrated. When the temperature of the outer surface is not more than the above upper limit, shrinkage and cutting of the polyethylene fiber can be effectively suppressed.

Further, the polyethylene fibers 5 are pressed against the tubular body 11Y by the pressing rolls 35 arranged in the circumferential direction. As a result, when the shape of the outer surface is distorted, the shape can be corrected.

The tubular body 11Y on which the polyethylene fibers 5 are arranged is shaped into a predetermined outer diameter by using a forming tube 34B installed on the inner surface of the second water tank 33B. Further, the tubular body 11Y is cooled in the second water tank 33B. In this way, the resin tube 11 provided with the polyethylene-polyethylene fiber composite layer can be obtained.

In the production methods (1) and (2), when a part of the polyethylene fiber is exposed, polyethylene may be further coated so as to cover the exposed polyethylene fiber.

Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to the following examples.

The following materials were prepared.

High-density polyethylene (HDPE, Asahi Kasei "PE100", density 0.950 g / cm ³ )
Polyethylene fiber (twisted yarn, YGK "Assist Line Seki Yarn No. 0.8", crystallinity 95%)
Nylon fiber (twisted yarn, Yamatoyo Tegus Co., Ltd. "YAMATOYO Line GAI M Nylon No. 2")

(Example 1)
A resin tube having the structure shown in Table 1 was produced by using the high-density polyethylene and the polyethylene fiber by the above-mentioned production method (2). Specifically, it was produced as follows.

A tubular body having a three-layer structure was prepared using high-density polyethylene. The surface of the obtained tubular body was heated with an IR heater. The temperature of the outer surface of the tubular body was controlled to 140 ° C. ± 20 ° C. In addition, a bobbin in which polyethylene fiber twisted yarn is wound with a predetermined number of turns is prepared, and twisted yarn with a certain tension is applied to the tubular body from the bobbin arranged at regular intervals in the circumferential direction of the tubular body. A plurality of fibers were put into the outer surface of the tubular body, the tubular body was rotated at a constant speed by a rotary take-up machine, and twisted yarns were spirally arranged on the outer surface of the tubular body. Next, the twisted yarn was pressed against the tubular body by a pressing roll installed in the circumferential direction of the tubular body. Then, a forming tube installed in the water tank was used to shape the outer diameter to a predetermined size to obtain a resin tube. The obtained resin tube had a portion where polyethylene fibers were exposed from the outer surface of the resin tube.

(Example 2)
A resin tube was produced in the same manner as in Example 1 except that the number of polyethylene fibers was changed as shown in Table 1.

(Comparative Example 1)
A resin tube was produced in the same manner as in Example 1 except that nylon fibers were used instead of polyethylene fibers and the structure was changed so as to have the structure shown in Table 1.

(Comparative Example 2)
A resin tube (single-layer tube) was produced in the same manner as in Example 1 except that fibers were not used.

(evaluation)
(1) Pressure resistance A water pressure was applied to the obtained resin tube at a step-up rate of 0.11 MPa / sec, and the breaking water pressure until the resin tube was cracked or cracked was determined.

[Criteria for pressure resistance]
◯: Breaking water pressure is 6.4 MPa or more ×: Breaking water pressure is less than 6.4 MPa

(2) Average value of fiber inclination angle A total of three lines separated in the circumferential direction along the axial direction of the resin tube were drawn from any point on the outer surface of the obtained resin tube (lines A and B). , C). At the position A on the line A, the position B on the line B, and the position C on the line C, the inclination angle θ was measured using a protractor having bendability. The positions A to C are positions separated from each other by about 4 m in the axial direction of the resin pipe. The average value of the obtained inclination angles θ at the three locations was calculated.

The configuration and results of the resin tube are shown in Table 1 below.

1,1A, 1B, 1C ... Polyethylene-polyethylene fiber composite layer 2,2B ... Second layer 3,3B ... Third layer 5 ... Polyethylene fiber 11, 11A, 11B, 11C ... Resin tube 11X, 11AX, 11Y ... Tubular body 20 ... Mold 21 ... Bobbin 22 ... Tensioner 23 ... Water tank 24 ... Forming tube 30 ... Heating device 31 ... Bobbin 32 ... Tensioner 33A ... First water tank 33B ... Second water tank 34A, 34B ... Forming tube 35 ... Presser Roll L ... Spiral direction X ... Axial direction Y ... Circumferential direction

Claims (7)

It ’s a resin tube,
With a polyethylene-polyethylene fiber composite layer containing polyethylene and polyethylene fibers,
The polyethylene fiber is a polyethylene fiber having a crystallinity of 95% or more and having molecules oriented in one direction.
A resin tube in which the polyethylene fibers are spirally arranged along the axial direction of the resin tube. The resin tube according to claim 1, wherein the polyethylene-polyethylene fiber composite layer is the outermost layer of the resin tube. The resin tube according to claim 1 or 2, wherein the average value of the inclination angles of the polyethylene fibers from the axial direction to the circumferential direction of the resin tube is 40 degrees or more and 80 degrees or less. The resin tube according to any one of claims 1 to 3, wherein the polyethylene fiber is a polyethylene fiber made of twisted yarn. The average diameter of the twisted yarn is 0.15 mm or more.
The resin tube according to claim 4, wherein the number of twisted yarns arranged per circumference of the resin tube is 720 or more. The method for manufacturing a resin tube according to any one of claims 1 to 5.
The process of extruding a tubular body with polyethylene on the outer surface from the mold,
A step of spirally arranging the polyethylene fibers on the outer surface of the tubular body extruded from the mold, and
A method for producing a resin tube, comprising a step of cooling the tubular body on which the polyethylene fiber is arranged to obtain a resin tube having the polyethylene-polyethylene fiber composite layer. The method for manufacturing a resin tube according to any one of claims 1 to 5.
The process of extruding a tubular body with polyethylene on the outer surface from the first water tank,
A step of heating the outermost layer of the tubular body extruded from the first water tank to obtain the outermost layer in a molten state, and
A step of spirally arranging the polyethylene fibers on the outer surface of the outermost layer in a molten state, and
A method for producing a resin tube, comprising a step of cooling the tubular body on which the polyethylene fibers are arranged in a second water tank to obtain a resin tube having the polyethylene-polyethylene fiber composite layer.

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