resin pipe

Abstract

We provide resin pipes with excellent installation reliability. [Solution] The resin pipe 1 of this disclosure comprises a pipe body 10 and a recess 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, wherein the depth of the recess 20 from the outer surface of the pipe body 10 is 0.4 mm or less. In addition, a plurality of recesses 20 may be provided in the circumferential direction of the pipe body 10.

Description

[Technical Field]

[0001] This invention relates to resin pipes. [Background technology]

[0002] Generally, when connecting a resin pipe to an electrofusion joint, the end of the resin pipe was scraped, and this scraped portion was inserted into the electrofusion joint and fused.

[0003] If the scraping process is insufficient, the full effect of the scraping process may not be achieved, and it may become difficult to insert the resin pipe into the electrofusion joint. Therefore, careful scraping is required, which can lead to cumbersome work. In addition, variations in workmanship can occur depending on the person performing the work, resulting in inconsistent installation.

[0004] To address these problems, for example, Patent Document 1 discloses a heat-sealable resin pipe in which an identification portion having a layer or pattern of a different color from the inside of the pipe is formed on the pipe surface, so that the appropriate range and depth for scraper treatment can be determined. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 06-002794 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, even if an identification section is formed as in Patent Document 1, there is a risk of water leakage if the scraper treatment is incomplete.

[0007] Furthermore, during construction, it is common practice to conduct a short-term water pressure test lasting a few minutes to confirm that the fusion between the scraped resin pipe and the fitting is sufficient. However, even if the scraping of the resin pipe is incomplete (faulty scraping), the problem may not be revealed in the short-term water pressure test, and the construction may be completed with the faulty scraping overlooked. This could lead to water leakage over time.

[0008] This invention was made in consideration of these circumstances, and aims to provide a resin pipe with excellent reliability in construction. [Means for solving the problem]

[0009] To solve the above problems, this invention proposes the following means. (1) The pipe comprises a pipe body and a recess provided on the outer surface of the pipe body and extending in the direction of the pipe axis of the pipe body, wherein the depth of the recess from the outer surface of the pipe body is 0.4 mm or less. (2) Multiple recesses may be provided in the circumferential direction of the pipe body. (3) The surface of the recess may have an oxide film. (4) The cross-sectional shape of the recess may have a taper that decreases in diameter toward the pipe axis of the pipe body. [Effects of the Invention]

[0010] This invention provides a resin pipe with excellent installation reliability. [Brief explanation of the drawing]

[0011] [Figure 1] This is a perspective view of a resin tube according to one embodiment of the present disclosure. [Figure 2] This is a cross-sectional view of the resin tube shown in Figure 1, along line II-II. [Figure 3] This is an example of a resin pipe that has been scraped. [Figure 4] This is an example of a resin pipe with incomplete scraping. [Figure 5]It is a partial enlarged view of the concave portion shown in FIG. 4. [Figure 6] It is a first modification of the configuration of the concave portion, where (a) is a side view of the resin tube and (b) is an end view of the resin tube. [Figure 7] It is a second modification of the configuration of the concave portion, where (a) is a side view of the resin tube and (b) is an end view of the resin tube.

Embodiments for Carrying Out the Invention

[0012] As shown in FIGS. 1 and 2, the resin tube 1 of the present disclosure is a resin tube that scrapes the surface of the end portion and performs electric fusion bonding, and includes a tube body 10 and a concave portion 20 provided on the outer surface of the tube body 10 and extending in the tube axis O1 direction of the tube body 10.

[0013] Hereinafter, an embodiment of the resin tube 1 according to the present disclosure will be described with reference to FIGS. 1 to 8. The concave portion 20 extends in the tube axis O1 direction of the tube body 10. The concave portion 20 extends over the entire length of the tube body 10 in the tube axis O1 direction. Also, in the present embodiment, two concave portions 20 are provided so as to be opposed to each other with the tube axis O1 interposed therebetween on a plane passing through the tube axis O1 of the tube body 10. The number of the concave portions 20 is not limited, and it may be one or three or more. However, from the viewpoint of construction reliability described later, it is preferable that a plurality of concave portions 20 are provided. When the number of the concave portions 20 is plural, the concave portions 20 may be provided at equal intervals or at unequal intervals. [[ID=*21]]

[0014] The length of the resin tube 1 is determined according to the use of the resin tube 1. For example, it is preferably 2 m or more and 10 m or less. Here, the length of the tube body 10 is the distance from one open end to the other open end. The inner diameter R1 of the resin tube 1 is determined according to the use of the resin tube 1. For example, it is preferably 10 mm or more and 600 mm or less. The tube body 10 is formed such that its outer diameter is substantially equal to the inner diameter of the fusion joint inserted after the scraping treatment.

[0015] The color of the pipe body 10 is not particularly limited and is determined appropriately according to the application and purpose.

[0016] The resin constituting the pipe body 10 is polyethylene. The polyethylene content in the pipe body 10 is 100 parts by mass per 100 parts by mass of resin. The resin constituting the pipe body 10 may also be a polyolefin resin.

[0017] The resin can be low-density polyethylene, medium-density polyethylene, or high-density polyethylene. Of these, high-density polyethylene is preferred. 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 one of the categories 1-1 to 6 in Annex Table 2. The density of low-density polyethylene is 910 kg / m³. 3 More than 930kg / m 3 It is less than. Medium-density polyethylene meets the requirements of one of the categories 1 through 5 in Annex Table 2. The density of medium-density polyethylene is 930 kg / m³. 3 More than 942kg / m 3 It is less than. High-density polyethylene meets the requirements of one of the categories 1 through 5 in Annex Table 2. The density of high-density polyethylene is 942 kg / m³. 3 That's all. As described in Appendix Tables 1 and 2, polyethylene types are classified by a combination of "type" and "class," such as "● type ● category."

[0018] The resin melt flow rate (MFR) is preferably, for example, 0.01 g / 10 min to 200 g / 10 min, more preferably 0.1 g / 10 min to 100 g / 10 min, even more preferably 0.2 g / 10 min to 50 g / 10 min, and particularly preferably 0.3 g / 10 min to 10 g / 10 min. The melt flow rate (MFR) of the resin was measured according to Annex 4.1 (Melt Flow Rate) of JIS K 6922-2:2010, at a test temperature of 190°C and a test load of 21.18N.

[0019] The tensile strength of the 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 resin is usually 100 MPa. The tensile strength of the resin is the value measured in accordance with 4.3 (Tensile Test) in the appendix of JIS K 6922-2:2010.

[0020] The tensile elongation at break of the resin is preferably 100% or more, more preferably 300% or more. The upper limit of the tensile elongation at break of the resin is usually 1000%. The tensile elongation at break of the resin is the value measured in accordance with 4.3 (Tensile Test) in the appendix of JIS K 6922-2:2010.

[0021] The durometer hardness of the resin is preferably 30H D D or more, more preferably 60H D D or more, even more preferably 65H D D or more. The upper limit of the durometer hardness of the resin is usually 200H D D. The durometer hardness of the resin is the value measured in accordance with 4.4 (Durometer D Hardness Test) in the appendix of JIS K 6922-2:2010.

[0022] The Vicat softening point of the resin is preferably 65°C or more, more preferably 90°C or more, and even more preferably 100°C or more. The upper limit of the Vicat softening point of the resin is usually 150°C. The Vicat softening point of the resin is the value measured in accordance with 4.5 (Vicat Softening Point Test) in the appendix of JIS K 6922-2:2010.

[0023] The mass average molecular weight of the resin is preferably 0.5×10 5 or more and 10.0×10 5 or less, more preferably 1.5×10 5 or more and 3.0×10 5 or less. If the mass average molecular weight is within the above range, the fluidity of the resin becomes appropriate and the productivity can be enhanced. The mass-average molecular weight of the resin is measured according to JIS K 7252-1:2008.

[0024] The number-average molecular weight of the resin is 0.1 × 10⁻⁶. 4 The above 2.0 × 10 4 The following is preferable: 0.5 × 10 4 The above 1.0 × 10 4 The following is more preferable: If the number-average molecular weight is within the above range, the fluidity of the resin will be appropriate, and productivity can be increased. The number-average molecular weight of the resin is measured in accordance with JIS K 7252-1:2008.

[0025] The glass transition temperature of the resin is preferably between -140°C and -90°C, and more preferably between -120°C and -100°C. If the glass transition temperature is within the above range, the fluidity of the resin will be appropriate, and productivity can be increased. The glass transition temperature of a resin is a value measured by differential scanning calorimetry (DSC).

[0026] The melting point of the resin is preferably between 110°C and 130°C, and more preferably between 120°C and 125°C. If the melting point is within this range, the fluidity of the resin will be appropriate, thereby increasing productivity. The melting point of a resin is a value measured by a differential scanning calorimetry (DSC).

[0027] The degree of crystallinity of the resin is preferably between 60% and 80%, and more preferably between 65% and 70%. If the degree of crystallinity is within the above range, the fluidity of the resin will be appropriate, and productivity can be increased. The degree of crystallinity of a resin is a value measured by DSC.

[0028] The pencil hardness of the resin is preferably between HB and 7B, and more preferably between HB and 6B. If the pencil hardness is within the above range, it becomes less prone to scratches, and the appearance can be further improved. The pencil hardness of the resin is measured according to JIS K 5600-5-4:1999.

[0029] The resin content is preferably 90% by mass or more and 99.99999% by mass or less, based on the total mass of the tube body 10.

[0030] The tube body 10 may contain additives such as colorants, antioxidants, ultraviolet absorbers (UVA), and hindered amine light stabilizers (HALS). The amount of additive in the tube body 10 is determined considering the type of additive. The amount of additive per 100 parts by mass of resin is 1.0 × 10 -5 Preferably, it is between parts by mass and 10 parts by mass, or 1.0 × 10 -3 Parts by mass or more and 1.0 part by mass or less is more preferable.

[0031] The surface of the resin pipe 1 may have an oxide film. The surface of the recess 20 may also have an oxide film.

[0032] In this embodiment, the length of the recess 20 is the same as the length of the pipe body 10.

[0033] In this embodiment, the cross-sectional shape of the recess 20 has a taper that decreases in diameter toward the pipe axis O1 of the pipe body 10. In other words, the cross-sectional shape of the recess 20 is V-shaped. The angle θ between the two tapered surfaces of the recess 20 is preferably 60 degrees or more, and more preferably 90 degrees or more, from the viewpoint of improving the construction reliability described later. The cross-sectional shape of the recess 20 is not limited to the above, and may be U-shaped, for example.

[0034] The depth d2 of the recess 20 from the outer surface of the pipe body 10 (depth of recess 20) shall be 0.4 mm or less. If the depth d2 of the recess 20 is 0.4 mm or less, it corresponds to the thickness of two scraping passes using a 0.2 mm blade commonly used at construction sites, so the recess 20 can be removed without impairing workability. The depth of the recess 20 is more preferably 0.2 mm or less. The depth d2 is the radial size of the recess 20. The depth d2 is the size from the inner edge to the outer edge of the recess 20, with the inner edge in the radial direction as the reference point. The radial outer edge of the recess 20 is the virtual outer surface of the resin pipe 1 assuming that the recess 20 does not exist. This virtual outer surface can be assumed, for example, by extending the adjacent portion of the recess 20 in the circumferential direction in the circumferential direction. The depth d2 of the recess 20 may be measured, for example, based on an image taken of the end face of the resin pipe 1.

[0035] The width w2 of the recess 20 (i.e., the length in the circumferential direction of the resin pipe 1) is determined as appropriate. The ratio of the width w2 of the recess 20 to the circumferential length of the pipe body 10 affects the strength of the resin pipe 1. Considering the balance between the detection accuracy of scraper processing defects and the strength of the resin pipe 1, the ratio of the width w2 to the outer circumference of the resin pipe 1 (circumferential length around the pipe axis O1) (w2 ratio) is preferably 0.1 to 20%, and more preferably 0.1 to 5%. The w2 ratio can be calculated as [width w2 of recess 20] ÷ [circumference of resin pipe 1] × 100. Furthermore, the specific width of the recess 20 is not limited, but for example, it may be between 1 mm and 20 mm. The width of the recess 20 is preferably between 1 mm and 5 mm, taking into consideration the balance between the detection accuracy of scraper processing defects and the strength of the resin pipe 1.

[0036] In this embodiment, when multiple recesses 20 are provided in the circumferential direction, it is preferable that the total width of the recesses 20 relative to the outer circumference of the pipe body 10 is less than 30%, taking into consideration the balance between the detection accuracy of scraper processing defects and the strength of the resin pipe 1. It is more preferable that the total width of the recesses 20 relative to the outer circumference of the pipe body 10 is less than 20%, and even more preferable that it is less than 15%.

[0037] Next, the scraper treatment of the resin pipe 1 in this embodiment will be described with reference to Figures 3 to 5. Figure 3 shows the resin pipe 1 after the scraping process is complete. The scraping process is considered complete when the recesses 20 have been removed by the scraping process and the outer surface of the pipe body 10 no longer has recesses 20. In other words, the scraping process can be considered complete when the depth s1 removed by the scraping process (scraping depth) is greater than or equal to the depth d2 of the recess 20 from the outer surface of the pipe body 10. Figure 4 shows a resin pipe 1 in a state where the scraping process is incomplete. Incomplete scraping means that at least a portion of the recess 20 remains on the outer surface of the pipe body 10 after scraping. In other words, if the depth scraped by the scraping process (scraping depth) s2 is less than the depth d2 of the recess 20 from the outer surface of the pipe body 10, then the scraping process is incomplete.

[0038] Figure 5 shows a magnified view of a portion of the resin pipe 1 in a state where the scraping process is incomplete. If a resin pipe 1 with incomplete scraper treatment is fused to a fusion joint, the recesses 20 remaining on the surface of the scraped portion will cause fusion failure. When recesses 20 cause fusion failure, a space is created between the surface of the recesses 20 and the inner surface of the fusion joint. This space between the surface of the recesses 20 and the inner surface of the fusion joint becomes a water channel that causes water leakage between the resin pipe 1 and the fusion joint when water is passed through the pipe, for example, during a water pressure test immediately after construction. Therefore, if the scraper treatment is incomplete, water leakage can be reliably caused even in a short-term water pressure test. If it is discovered that the scraper treatment is incomplete due to the occurrence of water leakage, the connection between the resin pipe 1 and the fusion joint can be reliably completed by performing scraper treatment until the recesses 20 are completely removed, as shown in Figure 3.

[0039] As described above, the resin pipe 1 of this disclosure comprises a pipe body 10 and a recess 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, wherein the depth of the recess 20 from the outer surface of the pipe body 10 is 0.4 mm or less. With this configuration, if the scraper processing depth is not greater than or equal to the depth of the recess 20 (i.e., the scraper processing is insufficient), at least a portion of the recess 20 will remain on the surface of the scraped portion of the pipe body 10. If a portion of the recess 20 remains on the surface of the scraped portion of the pipe body 10, the recess 20 remaining on the surface of the scraped portion will cause a fusion failure during electrofusion. Since the fused recess 20 becomes a water channel, it can cause water leakage during the water pressure resistance test. Therefore, it is possible to more reliably determine whether or not the scraper processing is insufficient through the water pressure resistance test. Thus, a resin pipe 1 with excellent construction reliability can be obtained.

[0040] Furthermore, multiple recesses 20 may be provided in the circumferential direction of the pipe body 10. In this disclosure, a scraping defect is detected by the recess 20, but a scraping defect cannot be detected in areas where the recess 20 is not provided. With the above configuration, multiple recesses 20 capable of detecting scraping defects can be provided in the circumferential direction of the pipe body 10. Therefore, the probability of a scraping defect overlapping with a recess 20 can be increased, and scraping defects can be detected more reliably in the water pressure resistance test. Thus, a resin pipe 1 with even greater construction reliability can be obtained.

[0041] Furthermore, the surface of the recess 20 may have an oxide film. With this configuration, the remaining recesses 20 in the scraped areas have an oxide film on their surface. The oxide film remaining on the surface of the recesses 20 causes fusion failure during electrofusion. The fusion failure in the recesses 20 with an oxide film on their surface can cause water leakage during the water pressure test. Therefore, scraping defects can be detected more reliably in the water pressure test. Thus, the resin pipe 1 can be made even more reliable in terms of installation.

[0042] Furthermore, the cross-sectional shape of the recess 20 may have a taper that decreases in diameter toward the pipe axis O1 of the pipe body 10. Generally, scraping is performed using a blade that rotates on a surface perpendicular to the pipe axis O1 of the pipe body 10 (circumferential direction of the pipe). In this case, the blade may get caught in the recess 20, and the recess 20 may hinder the blade's smooth movement. With the above configuration, since the recess 20 has a tapered surface, it is possible to suppress the blade getting caught in the recess 20. Therefore, the recess 20 does not hinder the blade's smooth movement, and the worker can reliably perform scraping. Thus, a resin pipe 1 can be made that is excellent in terms of both construction reliability and workability.

[0043] 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 modifications, combinations, deletions, etc., of the configuration are also included without departing from the spirit of the present invention.

[0044] For example, a stencil may be provided on the outer surface of the resin pipe 1. For example, as shown in Figures 6 and 7, the recesses 20 may be provided as a pattern for identifying the type of resin pipe 1. Specifically, for example, as shown in Figure 6, multiple recesses 20 (three in the illustrated example) may be unevenly distributed and provided parallel to the pipe axis O1 of the pipe body 10. For example, as shown in Figure 7, a pattern may be drawn on the surface of the pipe body 10 using the recesses 20. When a pattern is provided on the surface of the pipe body 10 using the recesses 20 as shown in Figure 7, a part of the mold of the manufacturing apparatus may be made into a roller type, and the pattern may be imprinted by rotating the pattern forming member while pressing it against the pipe surface during extrusion molding. In a side view of the resin pipe 1 with the recesses 20 viewed from the radial outside, multiple rectangular (square in the illustrated example) unit recesses 20a are arranged in the direction of the pipe axis O1. In the unit recesses 20a, the diagonal of the rectangle is parallel to the pipe axis O1. [Explanation of Symbols]

[0045] 1. Resin pipe 10-tube body 20 recesses

Claims

1. The main body of the pipe and A recess is provided on the outer surface of the pipe body, extending in the direction of the pipe axis of the pipe body, Equipped with, The depth of the recess from the outer surface of the pipe body is 0.4 mm or less. Plastic pipe.

2. Multiple recesses are provided in the circumferential direction of the pipe body. The resin pipe according to claim 1.

3. The surface of the recess has an oxide film, The resin pipe according to claim 1 or 2.

4. The cross-sectional shape of the recess has a taper that decreases in diameter toward the pipe axis of the pipe body. The resin pipe according to claim 1 or 2.

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