JP2008302622A - Multi-layered tubular material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multi-layered tubular material which can be produced at a low manufacture cost with short working hours, wherein the leak of smelling organic ingredients caused by a cross-linking reaction into water in the tube can effectively be prevented and also the infiltration of organic ingredients from outside into the tube can be prevented. <P>SOLUTION: In the multi-layered tubular material, a thermoplastic resin coating layer which does not permeate organic ingredients is formed on an inner surface of the body of the tubular material made of cross-linked polyethylene. The thermoplastic resin for forming the coating layer is preferably at least one selected from the group consisting of a polyolefin, a polyfluorinated vinylidene and a polyamide. Preferable coating layer comprises a thermoplastic resin containing an adsorbing agent. As the adsorbing agent, use is often made of zeolite, activated carbon and other porous material. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a multilayer pipe material such as water supply or hot water supply, in which a coating layer that does not allow organic components such as odorous substances to pass through is provided on the inner surface of a cross-linked polyethylene pipe body.

  Cross-linked polyethylene is obtained by subjecting polyethylene to a cross-linking reaction such as a peroxide cross-linking method (Engel method) or a silane cross-linking method, and is excellent in high-temperature creep characteristics at 120 ° C. or lower compared to ordinary polyethylene. In view of such characteristics, it is often used as a piping material for hot water supply or heating.

  However, since the crosslinked polyethylene is obtained by the method as described above, it contains a small amount of a relatively low molecular weight odorous organic component produced during the crosslinking reaction, and this gradually dissolves in water or hot water in the crosslinked polyethylene tube. And cause unpleasant odors.

Conventionally, as a solution to this problem, a method has been proposed in which a cross-linked polyethylene pipe is heat-treated at 40 to 140 ° C. for 1 to 150 hours to remove odorous organic components from the pipe (see Patent Document 1). .
Japanese Patent No. 2535376

  However, in the method of the above-mentioned patent document 1, it takes a great manufacturing cost to heat the crosslinked polyethylene pipe and requires a long processing time. In addition, when the pipe is buried underground or in an exposed pipe. When the liquid is applied, there is a problem that organic components in the soil or organic components in the applied liquid enter the inside from the outer surface of the pipe and contaminate the water in the pipe.

  The present invention has been devised to overcome such problems, and can be manufactured at low cost, with a short working time, and in addition, odorous organic components resulting from the crosslinking reaction are eluted in the pipe water. Accordingly, it is an object of the present invention to provide a multilayer tube material that can effectively prevent the penetration of an organic component from the outside and effectively prevent the penetration of the organic component from the outside.

  In the multilayer pipe material according to the present invention, an organic component non-permeable thermoplastic resin coating layer is provided on the inner surface of a cross-linked polyethylene pipe body.

  In the present invention, the crosslinked polyethylene constituting the tube body of the multilayer tube material is obtained by a known method such as an Engel method or a silane crosslinking method, and is described in, for example, Japanese Patent Publication No. 45-35658 and Japanese Patent Publication No. 48-1711. Can be suitably employed. A method of forming a tube body from crosslinked polyethylene can also be performed according to a known method. The pipe body made of cross-linked polyethylene may be of any size as long as it has specifications for commonly used hot water supply pipes, etc., and generally has an outer diameter of 6 to 200 mm and a thickness: It is a product having a length of 1 to 30 mm and a length of 4 to 100 m.

  In the present invention, the thermoplastic resin constituting the coating layer is preferably at least one selected from the group consisting of polyolefin, polyvinylidene fluoride and polyamide, and more preferably polyethylene. The general diameter of the tube body is about 2 mm. In this case, the thickness of the coating layer is 0.01 to 0.5 mm, preferably 0.05 to 0.2 mm.

  A preferred coating layer is a thermoplastic resin containing an adsorbent, and a porous material such as zeolite or activated carbon is often used as the adsorbent. The content of the adsorbent is 0.1 to 120 parts by weight, preferably 1 to 80 parts by weight with respect to 100 parts by weight of the thermoplastic resin. If the content of the adsorbent is too large, moldability such as cracking in the coating layer is deteriorated. If the content is too small, the effect of the adsorbent is not sufficiently exhibited.

  An organic component-impermeable thermoplastic resin coating layer is provided on the inner surface of a crosslinked polyethylene tube body, and a multilayer tube material is usually produced by multilayer extrusion molding.

  An adhesive layer may be interposed between the tube body and the coating layer. A multilayer tube having an adhesive layer is preferable in that the adhesive strength between the inner layer and the outer layer is increased.

  In order to confirm the effect of the present invention, an inner layer of 0.1 mm is formed by multilayer extrusion molding on the inner surface of a pipe having an inner diameter of 13 mm, 10 cc of water is put into a 10 cm pipe sample, and sensory evaluation is performed after heating at 80 ° C. for 24 hours. And it was confirmed that the smell in the pipe was gone.

  According to the multilayer tube material of the present invention, the manufacturing cost is low, the working time is short, and in addition, the odorous organic component resulting from the crosslinking reaction is effectively prevented from being eluted into the pipe water, and the external It is also possible to effectively prevent the organic component from penetrating into the pipe.

  Next, in order to specifically explain the present invention, some examples of the present invention and comparative examples for showing comparison with the examples will be given.

Example 1
100 parts by weight of low density polyethylene (“SF-720” manufactured by Nippon Polyethylene Co., Ltd.) and 5 parts by weight of activated carbon “PW-D” manufactured by Kuraray Chemical Co., Ltd. are supplied to a sub-extruder (caliber: 32 mm, L / D28). , 100 parts by weight of cross-linked polyethylene (Mitsui Chemicals “Linkron HHE740N”) and 5 parts of catalyst masterbatch (Mitsui Chemicals “HZ082”) were supplied to the main extruder (caliber: 40 mm, L / D24). , Multilayer extrusion molding is performed to form a multilayered tube material consisting of a 2 mm thick cross-linked polyethylene tube body and an organic component impermeable thermoplastic resin coating layer (thickness 0.1 mm) covering the entire inner surface of the tube. did.

  10 cc of water was placed in a 10 cm long sample of the multilayer tube thus obtained and heated at 80 ° C. for 24 hours.

Example 2
A multilayer tube material was obtained in the same manner as in Example 1 except that 10 parts by weight of activated carbon “PW-D” manufactured by Kuraray Chemical Co., Ltd. was used as the activated carbon.

Example 3
A multilayer tube material was obtained in the same manner as in Example 1 except that 100 parts by weight of high density polyethylene (“HY430” manufactured by Nippon Polyethylene Co., Ltd.) was used instead of low density polyethylene, and this was heat-treated in the same manner.

Example 4
A multilayer tube material was obtained in the same manner as in Example 1 except that 10 parts by weight of activated carbon “PW-K” manufactured by Kuraray Chemical Co., Ltd. was used as the activated carbon, and this was heat-treated in the same manner.

Example 5
A multilayer tube material was obtained in the same manner as in Example 1 except that 10 parts by weight of zeolite (“Absent” manufactured by Sakai Kogyo Co., Ltd.) was used instead of the activated carbon, and this was heat-treated in the same manner.

Example 6
A multilayer tube material was obtained in the same manner as in Example 1 except that 100 parts by weight of high-density polyethylene (“HY430” manufactured by Nippon Polyethylene Co., Ltd.) was used instead of low-density polyethylene and no activated carbon was used. Heat-treated.

Example 7
A multilayer tube material was obtained in the same manner as in Example 1 except that 100 parts by weight of polyamide (“CF6S” manufactured by EMS Showa Denko KK) was used instead of low-density polyethylene and no activated carbon was used. Heat-treated.

Comparative Example 1
For comparison, a cross-linked polyethylene pipe was heat-treated in the same manner as in Example 1 as a single-layer pipe.

Comparative Example 2
For comparison, a tube made of crosslinked polyethylene was prepared as a single-layer tube material (no heat treatment).

Sensory test The sensory test was done by the following method about the said multilayer pipe agent and the single layer pipe material.

Paneler: 10 people Evaluation Criteria Score 1: No odor at all
2 ... Odor cannot be specified
3 ... Smells slightly
4 ... smell
5 ... Smells strongly The average value of the scores of each panel was obtained. This is shown in Table 1.

  In Table 1, PE1 is low density polyethylene (“SF-720” manufactured by Nippon Polyethylene, PE2 is high density polyethylene (“HY430” manufactured by Nippon Polyethylene)), PA is polyamide (“CF6S” manufactured by EMS Showa Denko), PW -D means activated carbon "PW-D" manufactured by Kuraray Chemical Co., and PW-K means activated carbon "PW-K" manufactured by Kuraray Chemical.

  As can be seen from Table 1, the multilayer pipe materials of Examples 1 to 7 according to the present invention show an odor removing effect superior to those of Comparative Examples 1 and 2.

Claims (6)

A multilayer pipe material in which an organic component impermeable thermoplastic resin coating layer is provided on the inner surface of a cross-linked polyethylene pipe body. The multilayer pipe according to claim 1, wherein the thermoplastic resin is at least one selected from the group consisting of polyolefin, polyvinylidene fluoride, and polyamide. The multilayer pipe according to claim 1, wherein the coating layer is made of a thermoplastic resin containing an adsorbent. The multilayer pipe according to any one of claims 1 to 3, wherein the adsorbent is made of a porous body. The multilayer pipe according to claim 4, wherein the porous body is zeolite or activated carbon. The multilayer tube material according to any one of claims 1 to 5, wherein an adhesive layer is interposed between the tube body and the coating layer.