Resin pipe

Abstract

To provide a resin pipe with excellent installation reliability. [Solution] A resin pipe (1) for connection to an electric fusion joint, comprising a pipe body (10) and a band-shaped portion (20) that is visible from the outer surface of the pipe body (10) and extends in the direction of the pipe axis (O1) of the pipe body (10), the pipe body (10) having an inner layer (11) and a colored layer (12) provided on the outer surface of the inner layer (11), and at least one of the band-shaped portion (20) and the colored layer (12) is provided radially outward from the inner layer (11).

Description

[Technical Field]

[0001] The present invention relates to a resin pipe. [Background technology]

[0002] Generally, when connecting a resin pipe to an electric fusion joint, the end of the resin pipe is scraped, and the scraped portion is inserted into the electric fusion joint for welding.

[0003] If the scraper treatment is insufficient, the scraper treatment will not be effective and it may be difficult to insert the plastic pipe into the electric fusion joint. Therefore, the scraper treatment must be performed carefully, which is inconvenient and cumbersome. Furthermore, there will be errors in the work depending on the person performing the work, which will result in inconsistent installation.

[0004] To address these problems, for example, Patent Document 1 discloses a heat-sealable resin tube in which an identification portion having a layer or pattern of a different color from the interior of the tube is formed on the surface of the tube, making it possible to grasp the appropriate range and depth for scraper processing. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 06-002794 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when an identification part is formed as in Patent Document 1, there is a problem in that it is not possible to determine whether scraping has been properly completed in a part where no identification part is provided.

[0007] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a resin pipe that is excellent in installation reliability. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention proposes the following means. (1) A resin tube for connection to an electric fusion joint, comprising a tube body and a band-shaped portion provided on the outer surface of the tube body and extending in the axial direction of the tube body, the tube body having an inner layer and a colored layer provided on the outer surface of the inner layer, and at least one of the band-shaped portion and the colored layer being provided radially outward from the inner layer. (2) The pipe body further has an outermost layer provided on the outer surface of the colored layer. (3) The band portion is provided on the outer surface of the colored layer. (4) The band-shaped portion is provided on the outer surface of the outermost layer. (5) The band-shaped portion is provided on the outer surface of the inner layer. (6) The inner layer and the layer provided on the outer surface of the inner layer have different color tones. [Effects of the Invention]

[0009] According to the present invention, a resin pipe with excellent installation reliability can be provided. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view of a resin pipe according to a first embodiment of the present disclosure. [Figure 2] 2 is a cross-sectional view of the resin pipe shown in FIG. 1 taken along line II-II. [Figure 3] FIG. 10 is a perspective view of a resin pipe according to a second embodiment of the present disclosure. [Figure 4] FIG. 4 is a VV cross-sectional view of the resin pipe shown in FIG. [Figure 5] FIG. 10 is a perspective view of a modified example of the resin pipe according to the second embodiment of the present disclosure. [Figure 6] 7 is a cross-sectional view taken along the line VII-VII of the resin pipe shown in FIG. 4. [Figure 7] 1A and 1B are explanatory diagrams of the scraper treatment of a resin pipe according to the present disclosure, in which (a) shows the resin pipe before the scraper treatment, (b) shows the resin pipe in a state where imperfect scraping remains after the scraper treatment, and (c) shows the resin pipe in a state where the scraper treatment is completed. DETAILED DESCRIPTION OF THE INVENTION

[0011] The resin pipe 1 of the present disclosure is a resin pipe 1 for connecting to an electric fusion joint by scraping the surface of the end, and comprises a pipe body 10 and a band-like portion 20 that is visible from the outer surface of the pipe body 10 and extends in the direction of the pipe axis O1 of the pipe body 10, the pipe body 10 having an inner layer 11 and a colored layer 12 provided on the outer surface of the inner layer 11, and at least one of the band-like portion 20 and the colored layer 12 is provided radially outward from the inner layer 11. Hereinafter, "provided on the outer surface" means "provided in contact with the outer surface." Hereinafter, a resin pipe 1 according to the present disclosure will be described with reference to the drawings.

[0012] (First embodiment) 1, the resin pipe 1A of the first embodiment has a pipe body 10 and a band-shaped portion 20 that is visible from the outer surface of the pipe body 10 and extends in the pipe axis O1 direction of the pipe body 10. The pipe body 10 has an inner layer 11, a colored layer 12 provided on the outer surface of the inner layer 11, and an outermost layer 13 provided on the outer surface of the colored layer 12. In this embodiment, a band-shaped portion 20 is provided on the outer surface of the inner layer 11. The band-shaped portion 20 penetrates the colored layer 12 and the outermost layer 13 in the radial direction. The entire inner layer 11 is covered from the radial outside by the band-shaped portion 20 or the colored layer 12 (outermost layer 13). The radial length d2 from the interface between the band-shaped portion 20 and the inner layer 11 to the pipe surface (thickness of the band-shaped portion 20) is equal to the radial length from the interface between the colored layer 12 and the inner layer 11 to the pipe surface (thickness of the colored layer 12 and the outermost layer 13). The band-shaped portion 20 extends over the entire length of the pipe body 10 in the direction of the pipe axis O1. The interface between the band-shaped portion 20 and the inner layer 11 and the interface between the colored layer 12 and the inner layer 11 are flush with each other.

[0013] As shown in FIG. 2, in this embodiment, the four band-shaped portions 20 are positioned annularly at intervals of 90° around the tube axis O1 of the tube main body 10. There are no limitations on the number or arrangement of the band-shaped portions 20 provided in the circumferential direction of the pipe body 10. The number of band-shaped portions 20 may be one, two, or three or more. When there are multiple band-shaped portions 20, the band-shaped portions 20 may be arranged at equal intervals in the circumferential direction of the pipe body 10, or some or all of the band-shaped portions 20 may be arranged at unequal intervals.

[0014] The length of the pipe body 10 is determined depending on the application of the resin pipe 1A, and is preferably, for example, 2 m or more and 10 m or less. Here, the length of the pipe body 10 is the distance from one open end to the other open end. The inner diameter R1 of the pipe body 10 is determined depending on the application of the resin pipe 1A, and is preferably, for example, 10 mm or more and 600 mm or less. The length d1 of the resin pipe 1A in the radial direction (thickness of the resin pipe 1A) is determined depending on the application of the resin pipe 1A, and is preferably, for example, 1 mm or more and 50 mm or less.

[0015] The color tones of the inner layer 11, colored layer 12, and outermost layer 13 of the pipe body 10 are not particularly limited and are determined appropriately depending on the application and purpose. From the viewpoint of detecting defective portions of the scraper treatment, it is preferable that the color tones of the inner layer 11 and colored layer 12 are different. More preferably, the color tones of the inner layer 11, colored layer 12, and outermost layer 13 are all different.

[0016] Although the specific thicknesses of the colored layer 12 and the outermost layer 13 are not limited, in this embodiment, the total thickness of the colored layer 12 and the outermost layer 13 (i.e., the total radial length of the colored layer 12 and the outermost layer 13) is equal to the thickness d2 of the strip portion 20. The total thickness of the colored layer 12 and the outermost layer 13 is preferably 0.4 mm or less. If the total thickness of the colored layer 12 and the outermost layer 13 is 0.4 mm or less, this corresponds to the thickness achieved by scraping twice using a 0.2 mm blade commonly used at construction sites, making it possible to remove the colored layer 12 and the outermost layer 13 without impairing workability. The total thickness of the colored layer 12 and the outermost layer 13 is more preferably 0.2 mm or less.

[0017] The first resin constituting the pipe body 10 may be polyethylene, for example, a polyolefin resin. The content of polyethylene in the pipe body 10 is 100 parts by mass per 100 parts by mass of the resin.

[0018] The first resin may be low-density polyethylene, medium-density polyethylene, or high-density polyethylene. Among these, high-density polyethylene is preferred as the first resin. The types of polyethylene are shown in Annex Tables 1 and 2 of JIS K 6922-1:1997. Low-density polyethylene meets the requirements of any of Class 1, Category 1 to Category 6 in Annex 2. The density of low-density polyethylene is 910 kg / m 3 More than 930kg / m 3 is less than. Medium density polyethylene meets the requirements of any of Class 2, Class 1 to Class 5 in Annex 2. The density of medium density polyethylene is 930 kg / m 3 More than 942kg / m 3 is less than. High density polyethylene meets the requirements of any of Class 3, Class 1 to Class 5 in Annex 2. The density of high density polyethylene is 942 kg / m 3 That's all. As shown in Annex Tables 1 and 2, types of polyethylene are classified by a combination of "type" and "class," such as "●type●class."

[0019] The melt flow rate (MFR) of the first resin is, for example, preferably 0.01 g / 10 min or more and 200 g / 10 min or less, more preferably 0.1 g / 10 min or more and 100 g / 10 min or less, even more preferably 0.2 g / 10 min or more and 50 g / 10 min or less, and particularly preferably 0.3 g / 10 min or more and 10 g / 10 min or less. The melt flow rate (MFR) of the first resin is a value measured in accordance with 4.1 (melt flow rate) of Appendix 1 of JIS K 6922-2:2010 at a test temperature of 190°C and a test load of 21.18N.

[0020] The tensile strength of the first resin is preferably 5.9 MPa or more, more preferably 19.6 MPa or more, and even more preferably 25 MPa or more. The upper limit of the tensile strength of the first resin is usually 100 MPa. The tensile strength of the first resin is a value measured in accordance with 4.3 (tensile test) of the appendix of JIS K 6922-2:2010.

[0021] The tensile elongation at break of the first resin is preferably 100% or more, more preferably 300% or more, and the upper limit of the tensile elongation at break of the first resin is usually 1000%. The tensile elongation at break of the first resin is a value measured in accordance with 4.3 (tensile test) of the appendix of JIS K 6922-2:2010.

[0022] The durometer hardness of the first resin is 30H D D or higher is preferable, 60H D D or higher is more preferable, 65H D The upper limit of the durometer hardness of the first resin is usually 200H D It's D. The durometer hardness of the first resin is a value measured in accordance with 4.4 (Durometer D hardness test) of Appendix 1 of JIS K 6922-2:2010.

[0023] The Vicat softening point of the first resin is preferably 65°C or higher, more preferably 90°C or higher, and even more preferably 100°C or higher. The upper limit of the Vicat softening point of the first resin is usually 150°C. The Vicat softening point of the first resin is a value measured in accordance with JIS K 6922-2:2010, Appendix 4.5 (Vicat softening point test).

[0024] The mass average molecular weight of the first resin is 0.5×10 5 Over 10.0 x 10 5 Less than 1.5 x 10 is preferable. 5 Over 3.0 x 10 5 The following is more preferable: If the mass average molecular weight is within the above range, the fluidity of the resin becomes appropriate, and productivity can be increased. The mass average molecular weight of the first resin is measured in accordance with JIS K 7252-1:2008.

[0025] The number average molecular weight of the first resin is 0.1×10 4 Over 2.0 x 10 4 Less than 0.5 x 10 is preferable. 4 Over 1.0 x 10 4 The following is more preferable: If the number average molecular weight is within the above range, the fluidity of the resin becomes appropriate, and productivity can be increased. The number average molecular weight of the first resin is measured in accordance with JIS K 7252-1:2008.

[0026] The glass transition point of the first resin is preferably −140° C. or higher and −90° C. or lower, and more preferably −120° C. or higher and −100° C. If the glass transition point is within the above range, the resin has appropriate fluidity, which increases productivity. The glass transition point of the first resin is a value measured by a differential scanning calorimeter (DSC).

[0027] The melting point of the first resin is preferably 110° C. or higher and 130° C. or lower, and more preferably 120° C. or higher and 125° C. or lower. If the melting point is within the above range, the resin has appropriate fluidity, which increases productivity. The melting point of the first resin is a value measured by a differential scanning calorimeter (DSC).

[0028] The crystallinity of the first resin is preferably 60% to 80%, more preferably 65% ​​to 70%. If the crystallinity is within the above range, the resin has appropriate fluidity, which increases productivity. The crystallinity of the first resin is a value measured by DSC.

[0029] The pencil hardness of the first resin is preferably HB or more and 7B or less, and more preferably HB or more and 6B or less. If the pencil hardness is within the above range, the resin is less susceptible to scratches and the appearance can be further improved. The pencil hardness of the first resin is a value measured in accordance with JIS K 5600-5-4:1999.

[0030] The content of the first resin is preferably 90% by mass or more and 99.99999% by mass or less with respect to the total mass of the pipe body 10.

[0031] The tube body 10 may contain additives such as colorants, antioxidants, ultraviolet absorbers (UVA), and hindered amine light stabilizers (HALS). The content of the additive in the pipe body 10 is determined taking into consideration the type of additive. The content of the additive per 100 parts by mass of the first resin is 1.0 × 10 -5 Parts by mass or more and 10 parts by mass or less are preferred, and 1.0 × 10 -3 Parts by mass or more and 1.0 parts by mass or less are more preferable.

[0032] The outermost layer 13 may be a barrier resin layer (functional layer) containing an ethylene-vinyl alcohol copolymer resin that is impermeable to gases such as hydrogen, oxygen, propane, and butane, and hydrocarbons such as gasoline and benzene. This allows the resin pipe 1A to be used for air conditioning, hot water supply, gas, or fuel. The type of functional layer is not limited, and it may be a layer containing inorganic fibers such as glass fiber, carbon fiber, silicon-titanium-carbon composite fiber, boron fiber, or metal fiber, or a layer containing organic fibers such as aramid fiber, vinylon fiber, polyester fiber, or polyamide fiber. Using a layer containing these fibers results in a pipe with high tensile strength and resistance to thermal expansion. Furthermore, using a layer containing fluororesin results in a pipe with high resistance to chemicals such as acids and alkalis.

[0033] The length of the band-shaped portion 20 is the same as the length of the pipe body 10. The length of the band-shaped portion 20 may be the same as or different from the length of the pipe body 10. The length of the band-shaped portion 20 is preferably the same as the length of the pipe body 10.

[0034] The width w2 of the strip portion 20 (i.e., the length of each strip portion 20 in the circumferential direction of the resin pipe 1) is determined appropriately depending on the purpose of the strip portion 20. The ratio of the width w2 to the outer circumference of the resin pipe 1 (the circumferential length around the pipe axis O1) (w2 ratio) is 1 to 30%, and preferably 1 to less than 5%. If the width w2 is less than 5%, the stripes can be easily removed during recycling, and if it is greater than 1%, the identification and visibility can be improved. The w2 ratio is calculated by [width w2 of the band-shaped portion 20]÷[circumferential length of the resin pipe 1A]×100.

[0035] When multiple band-like portions 20 are provided in the circumferential direction as in this embodiment, from the viewpoint of ensuring visibility, the width of each band-like portion 20 relative to the outer periphery of the pipe main body 10 is preferably 1 to 30%. More preferably, the width of each band-like portion 20 relative to the outer periphery of the pipe main body 10 is 1 to 5%.

[0036] The width of the strip portion 20 is not specifically limited, but may be, for example, 1 mm or more and 20 mm or less. From the viewpoint of ensuring visibility, the width of the strip portion 20 is preferably 2 mm or more.

[0037] The color tone of the belt-shaped portion 20 is not particularly limited, but is preferably different from the color tone of the outermost layer 13 . The color tone of the band-like portion 20 is different from the color tone of the outermost layer 13, so that a striped pattern appears on the outer periphery of the resin pipe 1A. Furthermore, by combining the colors of the band-like portion 20 and the outermost layer 13, the color variations of the resin pipe 1A are increased.

[0038] The second resin constituting the strip portion 20 is polyethylene containing low-density polyethylene, medium-density polyethylene, or a mixture thereof. The content of the second resin in the strip portion 20 is 100 parts by mass per 100 parts by mass of the resin.

[0039] The total content of the low-density polyethylene and the medium-density polyethylene per 100 parts by mass of the second resin is preferably 50 parts by mass or more, more preferably 80 parts by mass or more, and even more preferably 100 parts by mass. When the content is equal to or more than the above lower limit, the fluidity of the second resin is easily increased.

[0040] The second resin species and the first resin species may be the same or different. When the type of the second resin is different from the type of the first resin, it is preferable that the density of the second resin is smaller than the density of the first resin. If the density of the second resin is smaller than the density of the first resin, the fluidity of the second resin in the extruder is increased, and an increase in the back pressure of the extruder can be further suppressed. This further reduces the load on the extruder.

[0041] When the type of the second resin is the same as the type of the first resin, it is preferable that the second resin have a larger polyethylene "class" number in Appendix Table 2 of JIS K 6922-1:1997. That is, if the first resin is Class 2, Class 1, it is preferable that the second resin be Class 2, Class 2 to Class 5. By increasing the class number, the fluidity of the second resin in the extruder is improved, and an increase in the back pressure of the extruder can be further suppressed. This further reduces the load on the extruder.

[0042] Preferred examples of the combination of the first resin and the second resin are shown in (a), (b) and (c). (a) The first resin is high density polyethylene and the second resin is medium density polyethylene. (b) The first resin is high density polyethylene and the second resin is low density polyethylene. (c) The first resin is high density polyethylene and the second resin is a blend of low density polyethylene and medium density polyethylene.

[0043] The MFR of the second resin is preferably 0.1 g / 10 min or more and 200 g / 10 min or less, and more preferably 0.4 g / 10 min or more and 100 g / 10 min or less. The MFR of the second resin is preferably greater than the MFR of the first resin. The difference between the MFR of the second resin and the MFR of the first resin is preferably 0.3 g / 10 min or more, more preferably 1.0 g / 10 min or more. If the difference in MFR between the first resin and the second resin is within the above range, the appearance of the band-shaped portion 20 can be further improved and the load on the extruder can be further reduced. The upper limit of the difference between the MFR of the second resin and the MFR of the first resin is, for example, 20 g / 10 min.

[0044] The tensile strength of the second resin is preferably 5.9 MPa or more, more preferably 9.8 MPa or more, and the upper limit of the tensile strength of the second resin is usually 100 MPa. The difference between the tensile strength of the second resin and the tensile strength of the first resin is preferably 5.0 MPa or more, and more preferably 10.0 MPa or more. If the difference in tensile strength between the first resin and the second resin is within the above range, the appearance of the strip portion 20 can be further improved and the load on the extruder can be further reduced. The upper limit of the difference between the tensile strength of the second resin and the tensile strength of the first resin is, for example, 20 MPa.

[0045] The tensile elongation at break of the second resin is preferably 100% or more, more preferably 300% or more, and the upper limit of the tensile elongation at break of the second resin is usually 1000%. The difference between the tensile elongation at break of the second resin and the tensile elongation at break of the first resin is preferably 50% or more, and more preferably 100% or more. If the difference in tensile elongation at break between the first resin and the second resin is within the above range, the appearance of the band-shaped portion 20 can be improved and the load on the extruder can be further reduced. The upper limit of the difference between the tensile elongation at break of the second resin and the tensile elongation at break of the first resin is, for example, 200%.

[0046] The durometer hardness of the second resin is 30H D D or higher is preferred, 45H D The upper limit of the durometer hardness of the second resin is usually 100H D It's D. The difference in durometer hardness between the second resin and the first resin is 15H D D or higher is preferred, 30H D D or higher is more preferable. If the difference in durometer hardness between the first resin and the second resin is within the above range, the appearance of the band-shaped portion 20 can be improved and the load on the extruder can be further reduced. The upper limit of the difference between the durometer hardness of the second resin and the durometer hardness of the first resin is, for example, 50H. D It's D.

[0047] The Vicat softening point of the second resin is preferably 65°C or higher, and more preferably 80°C or higher. The upper limit of the Vicat softening point of the second resin is usually 130°C. The difference between the Vicat softening point of the second resin and the Vicat softening point of the first resin is preferably 5°C or more, more preferably 10°C or more. If the difference in Vicat softening point between the first resin and the second resin is within the above range, the appearance of the belt-shaped portion 20 can be improved and the load on the extruder can be further reduced. The upper limit of the difference between the Vicat softening point of the second resin and the Vicat softening point of the first resin is, for example, 30°C.

[0048] The mass average molecular weight of the second resin is 1.0×10 2 Over 2.0 x 10 5 Less than 1.5 x 10 is preferable. 3 Over 1.5 x 10 5 The following is more preferred: The difference between the mass average molecular weight of the second resin and the mass average molecular weight of the first resin is 1.5 × 10 5 More than 3.0 × 10 is preferable. 5 The above is more preferable. If the difference in mass average molecular weight between the first resin and the second resin is within the above range, the appearance of the strip portion 20 can be improved and the load on the extruder can be further reduced. The upper limit of the difference between the mass average molecular weight of the second resin and the mass average molecular weight of the first resin is, for example, 3.0 × 10 5 is.

[0049] The number average molecular weight of the second resin is 1.0×10 3 Over 10.0 x 10 3 Less than 1.5 x 10 is preferable. 3 Over 5.0 x 10 3 The following is more preferred:

[0050] The glass transition point of the second resin is preferably -135°C or higher and -95°C or lower, and more preferably -125°C or higher and -105°C or lower. The difference between the glass transition point of the second resin and the glass transition point of the first resin is preferably 0°C or more and 10°C or less, more preferably 0°C or more and 5°C or less. If the difference in glass transition point between the first resin and the second resin is within the above range, the appearance of the belt-shaped portion 20 can be improved and the load on the extruder can be further reduced.

[0051] The melting point of the second resin is preferably 100°C or higher and 120°C or lower, and more preferably 115°C or higher and 120°C or lower. The difference between the melting point of the second resin and the melting point of the first resin is preferably 0°C or higher and 10°C or lower, more preferably 0°C or higher and 5°C or lower. If the difference in melting point between the first resin and the second resin is within the above range, the appearance of the band-shaped portion 20 can be made better.

[0052] The crystallinity of the second resin is preferably 30% or more and 60% or less, and more preferably 40% or more and 60% or less. The difference between the crystallinity of the second resin and the crystallinity of the first resin is preferably 5% or more, and more preferably 10% or more. If the difference in crystallinity between the first resin and the second resin is within the above range, the appearance of the strip portion 20 can be improved and the load on the extruder can be further reduced. The upper limit of the difference between the crystallinity of the second resin and the crystallinity of the first resin is, for example, 50%.

[0053] The pencil hardness of the second resin is preferably HB or more and 7B or less, and more preferably HB or more and 6B or less. The difference in pencil hardness between the second resin and the first resin is preferably 2B or less, more preferably 1B or less. If the difference in hardness between the first resin and the second resin is within the above range, the appearance of the band-shaped portion 20 can be improved and the load on the extruder can be further reduced.

[0054] The content of the second resin with respect to the total mass of the strip portion 20 is preferably 90% by mass or more and 99.99999% by mass or less.

[0055] The band-shaped portion 20 may contain an additive. The additive contained in the band-shaped portion 20 is the same as the additive contained in the pipe main body 10. The additive in the pipe main body 10 and the additive in the band-shaped portion 20 may be the same or different. The content of the additive in the strip portion 20 is determined taking into consideration the type of additive. The content of the additive per 100 parts by mass of the second resin is 1.0×10 -5 Parts by mass or more and 10 parts by mass or less are preferred, and 1.0 × 10 -3 Parts by mass or more and 1.0 parts by mass or less are more preferable.

[0056] In this embodiment, the band-shaped portion 20 is provided on the outer surface of the inner layer 11, but the band-shaped portion 20 may be provided on the outer surface of the colored layer 12 instead of the outer surface of the inner layer 11. When the band-shaped portion 20 is provided on the outer surface of the colored layer 12, the colored layer 12 is formed continuously in the circumferential direction, and the thickness d2 of the band-shaped portion 20 is equal to the thickness of the outermost layer 13. In this case, the thickness of the band-shaped portion 20 is different from the sum of the thicknesses of the colored layer 12 and the outermost layer 13.

[0057] (Second embodiment) 3 and 4, the plastic pipe 1B of the second embodiment has a pipe body 10 and a band-like portion 20 provided on the outer surface of the pipe body 10 and extending in the direction of the pipe axis O1 of the pipe body 10. The pipe body 10 has an inner layer 11 and a colored layer 12 provided on the outer surface of the inner layer 11. Unlike the plastic pipe 1A of the first embodiment, the plastic pipe 1B of the second embodiment does not have an outermost layer 13. In this embodiment, a band-shaped portion 20 is provided on the outer surface of the inner layer 11. Therefore, the radial length d2 from the boundary between the band-shaped portion 20 and the inner layer 11 to the pipe surface is equal to the radial length from the boundary between the colored layer 12 and the inner layer 11 to the pipe surface. The band-shaped portion 20 extends over the entire length of the pipe body 10 in the direction of the pipe axis O1. In other words, the boundary between the band-shaped portion 20 and the inner layer 11 and the boundary between the colored layer 12 and the inner layer 11 are flush with each other.

[0058] Hereinafter, explanations of the configurations that are the same as those in the first embodiment, such as the number, arrangement, and material of the band-shaped portions 20, and the size and material of the pipe main body 10, will be omitted.

[0059] The color tones of the inner layer 11 and the colored layer 12 of the pipe body 10 are not particularly limited and are determined appropriately depending on the application and purpose. From the viewpoint of detecting defective portions of the scraper processing, it is preferable that the color tones of the inner layer 11 and the colored layer 12 are different.

[0060] Although the specific thickness of the colored layer 12 is not limited, in this embodiment, the thickness of the colored layer 12 is equal to the thickness of the strip portion 20. Therefore, the thickness of the colored layer 12 is preferably 0.4 mm or less. If the thickness of the colored layer 12 is 0.4 mm or less, it corresponds to the thickness of two scraping processes using a 0.2 mm blade that is commonly used at construction sites, and therefore the colored layer 12 can be removed without impairing workability. The thickness of the colored layer 12 is more preferably 0.2 mm or less.

[0061] The color tone of the belt-shaped portion 20 is not particularly limited, but is preferably different from the color tone of the colored layer 12 . The color tone of the band-shaped portion 20 is different from the color tone of the colored layer 12, thereby creating a striped pattern on the outer periphery of the resin pipe 1B. The color combination of the band-shaped portion 20 and the colored layer 12 increases the color variation of the resin pipe 1B. In addition, it is preferable that the color tone of the band-shaped portion 20 is different from the color tone of the inner layer 11 from the viewpoint of detecting defective portions of the scraper processing.

[0062] In this embodiment, the band-shaped portion 20 is provided on the outer surface of the inner layer 11. However, as shown in FIGS. 5 and 6, the band-shaped portion 20 may be provided on the outer surface of the colored layer 12 instead of on the outer surface of the inner layer 11. When the band-shaped portion 20 is provided on the outer surface of the colored layer 12, the colored layer 12 is formed continuously in the circumferential direction. In this case, the thickness of the band-shaped portion 20 is different from the thickness of the colored layer 12. Furthermore, when the band-shaped portion 20 is provided on the outer surface of the colored layer 12 instead of on the outer surface of the inner layer 11 as shown in FIGS. 5 and 6, the band-shaped portion 20 may be provided by printing on the outer surface of the colored layer 12.

[0063] 5 and 6 is a modified example of the resin pipe 1B of the second embodiment, but also in the resin pipe 1A of the first embodiment, the colored layer 12 and the outermost layer 13 may be formed continuously in the circumferential direction, and the band-like portion 20 may be provided only on the outer surface of the outermost layer 13. In this case, the band-like portion 20 may be provided on the outer surface of the outermost layer 13 by printing.

[0064] (Action and effect) Next, scraping of the resin pipes 1A, 1B, and 1C of the present disclosure will be described with reference to Fig. 7. Note that the following description will be given taking the resin pipe 1B of the second embodiment as an example. As shown in Figure 7(a), the resin pipe 1B has a band-like portion 20 and a pipe body 10, and the pipe body 10 has an inner layer 11 and a colored layer 12 provided on the outer surface of the inner layer 11. The details of the structure of the resin pipe 1B are as described above, so a detailed description will be omitted here.

[0065] 7(b) is a schematic diagram showing a case where a scrape defect 100 remains on the outer surface of the inner layer 11. The presence of a scrape defect 100 indicates a state in which at least a portion of the band portion 20 or colored layer 12 remains on the outer surface of the inner layer 11 after scraping. In other words, if the depth removed by the scraper process (scrapering depth) is less than the depth of the band portion 20 or colored layer 12, a scrape defect 100 remains, and the scraper process is incomplete.

[0066] If it is found that the scraping process is incomplete, the scraping process can be continued until the scraping defect 100 is completely removed, as shown in Figure 7(c), thereby ensuring the completion of the connection between the plastic pipe 1B and the fusion joint.

[0067] As described above, the resin tube 1 for connection to an electric fusion joint comprises a tube body 10 and a band-shaped portion 20 that is visible from the outer surface of the tube body 10 and extends in the direction of the tube axis O1 of the tube body 10, and the tube body 10 has an inner layer 11 and a colored layer 12 that is provided on the outer surface of the inner layer 11, and at least one of the band-shaped portion 20 and the colored layer 12 is provided radially outward from the inner layer 11. As mentioned above, if the band-shaped portion 20 is only provided on a portion of the outer surface of the resin pipe 1, it is not possible to determine whether the scraper process has been properly completed in the portion where the band-shaped portion 20 is not provided. With the above-described configuration, at least one of the band-shaped portion 20 and the colored layer 12 is provided radially outward from the inner layer 11. Therefore, for example, by providing the band-shaped portion 20 or the colored layer 12 to the depth to be scraped in the scraping process (scrapering depth), and checking the degree of removal of the band-shaped portion 20 or the colored layer 12 after the scraping process, it becomes possible to determine whether the scraping process has been properly completed around the entire outer periphery of the plastic pipe 1. In addition, the type of the plastic pipe 1 can be determined from the band-shaped portion 20. Therefore, the plastic pipe 1 can be provided with excellent installation reliability.

[0068] The pipe body 10 may further have an outermost layer 13 provided on the outer surface of the colored layer 12 . Even with this configuration, either the band portion 20 or the colored layer 12 is provided on the outer surface of the inner layer 11. Therefore, by checking the degree of removal of the band portion 20 or the colored layer 12 after scraping, it is possible to determine whether scraping has been properly completed around the entire outer periphery of the plastic pipe 1. This allows for a plastic pipe 1 with excellent installation reliability.

[0069] The strip portion 20 may also be provided on the outer surface of the colored layer 12 . In the present disclosure, even when only the colored layer 12 is provided on the surface of the inner layer 11, it is possible to determine whether the scraper treatment has been properly completed over the entire outer periphery of the resin pipe 1. Therefore, the band-like portion 20 does not need to be provided to the scraper treatment depth. With the above-described configuration, the band-shaped portion 20 can be provided, for example, by printing on the outer surface of the colored layer 12. This reduces the cost required to form the band-shaped portion 20, and makes it possible to determine whether scraping has been properly completed along the entire outer periphery of the plastic pipe 1. Furthermore, the type of the plastic pipe 1 can be determined by the band-shaped portion 20. This allows the plastic pipe 1 to be produced with excellent cost performance and installation reliability.

[0070] The strip portion 20 may also be provided on the outer surface of the outermost layer 13 . As previously mentioned, the strips 20 do not have to extend to the scraping depth. With the above-described configuration, the band-shaped portion 20 can be provided, for example, by printing on the outer surface of the outermost layer 13. This reduces the cost required to form the band-shaped portion 20, and makes it possible to determine whether scraping has been properly completed around the entire outer periphery of the plastic pipe 1. Furthermore, the type of the plastic pipe 1 can be determined by the band-shaped portion 20. This allows the plastic pipe 1 to be produced with excellent cost performance and installation reliability.

[0071] The band portion 20 may also be provided on the outer surface of the inner layer 11 . With this configuration, the radial length from the boundary between the band-shaped portion 20 and the inner layer 11 to the pipe surface is equal to the radial length from the boundary between the colored layer 12 and the inner layer 11 to the pipe surface. Therefore, for example, if the radial length from the boundary between the band-shaped portion 20 and the inner layer 11 to the pipe surface and the radial length from the boundary between the colored layer 12 and the inner layer 11 to the pipe surface are equal to the depth to be scraped in the scraping process (scrapering depth), checking the degree of removal of the band-shaped portion 20 and the colored layer 12 after the scraping process makes it possible to determine whether the scraping process has been properly completed around the entire outer periphery of the plastic pipe 1. Furthermore, the type of plastic pipe 1 can be determined based on the band-shaped portion 20. This allows the plastic pipe 1 to have excellent installation reliability.

[0072] Furthermore, the inner layer 11 and the layer provided on the outer surface of the inner layer 11 may have different color tones. Here, the layer provided on the outer surface of the inner layer 11 refers to a layer that is in contact with the outer surface of the inner layer 11. In the resin pipe 1 according to the first and second embodiments of the present disclosure, the layer provided on the outer surface of the inner layer 11 is, for example, the band-like portion 20 and the colored layer 12. With the above-described configuration, in the plastic pipe 1 after scraping, the color tone of the inner layer 11 is different from that of the layer provided on the outer surface of the inner layer 11. Therefore, if the layer provided on the outer surface of the inner layer 11 remains and causes a scraping defect 100, the color tone of the scraping defect 100 is different from that of the inner layer 11, making it easy to determine whether scraping has been properly completed around the entire outer surface of the plastic pipe 1. This allows for a plastic pipe 1 with better construction reliability.

[0073] Although one embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and configuration changes, combinations, deletions, etc. are also included within the scope that does not deviate from the gist of the present invention.

[0074] For example, a stencil may be provided on the outer surface of the resin pipe 1. [Explanation of symbols]

[0075] 1. Resin pipe 10 Tube body 11 Inner layer 12 Colored layer 13 Outermost layer 20 Belt

Claims

1. A resin tube for connecting to an electric fusion joint, A tube body; a band-shaped portion that is visible from the outer surface of the pipe body and extends in the pipe axis direction of the pipe body; Equipped with The pipe body has an inner layer and a colored layer provided on an outer surface of the inner layer, At least one of the band portion and the colored layer is provided radially outward from the inner layer. Resin pipe.

2. The pipe body further has an outermost layer provided on an outer surface of the colored layer. The resin pipe according to claim 1.

3. The band portion is provided on the outer surface of the colored layer. The resin pipe according to claim 1.

4. The band-shaped portion is provided on the outer surface of the outermost layer. The resin pipe according to claim 2.

5. The band-shaped portion is provided on the outer surface of the inner layer. The resin pipe according to claim 1.

6. The inner layer and the layer provided on the outer surface of the inner layer have different color tones. The resin pipe according to claim 1.

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