JPS5837391A - Polyethylene pipe - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Regarding ethylene pipes.

Pipes made of cross-linked polyethylene are considered promising for use in gas pipes, water pipes, hot water supply, etc. due to their excellent flexibility.

However, cross-linked polyethylene pipes have inferior joint properties compared to non-cross-linked polyethylene pipes, and they are also better suited for use as waste pipes and water pipes.
] Requires pressure resistance such as water resistance, and rigid abrasion resistance.

As a result of repeated research from this perspective, the inventors of the present invention have found that the following specific linear low-density polyethylene is used as a raw material and has unexpected 1-compression strength and 114M strength, and also has joint strength. It was discovered that a water-crosslinked polyethylene pipe with excellent properties could be obtained.

The present invention was completed based on this knowledge, and mp≧500×ψ−345 [where mp is the melting point peak determined by differential thermal analysis (°C
), ψ represents the elongation based on JIS K6760] This is a polyethylene pipe made of water-crosslinked polyethylene.

In the present invention, any water-crosslinked polyethylene used as a raw material can be used as long as it satisfies the above formula, or the maximum melting point peak (mp) is preferably about 160°C. Ru.

This single peak was measured by differential thermal analysis, and the measurement was carried out by Kanbara, Rin Fujiwara, [Cylinder Molecule Analysis Handbook, Section 3.15.1, P-178-188 (1965), Breakfast. This is based on the method described in the bookstore.

The preferred range of 8 degrees (ψ) according to JI8 K-6760 is 0.915 to 0.970. Especially from 0.918
It is 0.940.

Specific examples of such water-crosslinkable polyethylene include the following polyethylene resin compositions.

That is, (a) density 0.915 to 0.970 (7) po')
Ethi L/:/, especially linear low density polyethylene,
For linear medium density polyethylene, the general formula RR'S
i Y2 (R is a hydrocarbon group containing monovalent olefinic unsaturation, or hydrocarbonoxy group Y is a hydrolyzable organic group, R/ is a pore or a group Y), and (c) 140 It consists of a compound that generates free -l radicals in the high molecular weight polymer at temperatures above .degree. C. and (d) a silanol condensation catalyst. Examples of the component include well-known silane compounds such as Taton IJ hinyltriethoxysilane, vinyltrimethoxysilane, vinylmethyldimethoxysilane, and hinyltris(β-methoxy, ethoxy)silane. Component (C) includes dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)-hexyne-
Organic peroxide crosslinking agents such as 3,1,3-bis-(t-butylperoxy-isopropyl)-benzene, azobis-
Examples include azo compounds such as isobutyronitrile and dimethyl asodiisodibutyrate. (d) Components include dibutyl dilaurate, #l:tem-Thi
, carboxylic acid salts such as octanoic acid (caprylic acid primary), lead naphthenate, caprylic lead, 2-ethylhexane, cobalt naphthenate, organometallic acids such as titanate esters and chelates. Compounds such as titanate tetrabutyl ester, titanate tetranonyl ester and bis(acetylacetonitrile) di-isopropyl titanate, organic radicals such as ethylamine, hexylamine, dibutylamine and pyridine, acids such as free &M, acids and fatty acids etc.

(a) component 100i [each component per loading part (hereinafter referred to as "heavyweight part")] (b) component 0.1 to 50 parts, preferably 0.5 to IO parts, (c) component 0 .05 to 1.5 parts, preferably 0.01 to 0.2 parts, component (d) 0.005 to
5 parts, preferably 0. 1 to 0.5 parts of O.

The pipe of the present invention can be produced using the above-described water-crosslinkable polyethylene according to known molding/crosslinking methods and conditions. For example, to manufacture short products after several Vt1Itl, extrusion-molded uncrosslinked polyethylene pipes are cut into predetermined dimensions, and
By immersing in a water bath at 00'C for a period of time to reach a gel fraction of preferably at least 20%, particularly at least 50%, and for manufacturing long products of 100 m or more, drum winding is also used. The wall thickness of the pipe of the present invention varies depending on the inner diameter, and the larger the inner diameter, the larger the wall thickness. Or, for example,
Inner diameter 20M, 50MM, 100ff, 200u and 40
For 01M, 2~51N+ff, 3~7g, respectively
a+15~15m, 8~2 Qso*, and h15~3
It's about 0 cod or so.

Further, it is preferable that the gel fraction is at least 50%.

Hereinafter, the present invention will be explained in detail with reference to Examples and Comparative Examples.

EXAMPLES AND COMPARATIVE EXAMPLES A polyethylene resin composition having the composition shown in the table was extruded into a pipe shape, and this was immersed for 15 hours in a knitting machine at 90°C to obtain a pipe having the shape shown in the table. .

The thus obtained pipes were tested for water pressure strength, nail abrasion resistance, and joint fitting life, and the evaluation results are also listed in the table.

〔Test method〕

(1) Water pressure resistance strength: According to JIS K-6774.

(2) Abrasion resistance: ASTM Aθ1242 sand: water =
80 (1: 600 liters of slurry was cut from a pipe, and a M-width, 101-length bead was used as a transporting rod for 1200 liters.
pm for one hour, and the reduction in vertical violet before and after the test of the piece was expressed as a percentage.

Attach the Japan Water Works Association Standard-B-116 (7) joint fitting to a pipe with a diameter of near 00jljl and heat it to 80°CX1 at an internal pressure of 6#/d.
A heat cycle was performed with 20'C x 1 hour as one cycle, and the number of cycles at which the internal pressure decreased by 0.5 kti/d was expressed.

(Leaving space below) Procedural amendment (voluntary) 1. Indication of Jr. 1936 Patent Application No. 136820 2. Title of invention Polyethylene (Eve) 3. Relationship with the case of the person making the amendment Name of patent applicant (first name) b.) Nichifuden Wire Co., Ltd. 3, Contents of the amendment (1) Correction as per the appendix "Scope of Claims" on page 1 of the ministry (2) Sections from the bottom of page 1 of the ministry Line 8 says “water bridge” r “
Corrected to "water crosslinking".

(3) “Bridge polyethylene pipe” on page 2, line 8 of the Ministry
Corrected to ``Polyethylene pipe made of 5R polyethylene.''

(4) In the 2nd line of the same book, line 15, ``Water-crosslinked polyethylene'' is corrected to ``Water-crosslinked polyethylene that satisfies the needs of polyethylene pipes.'' (5) 2nd page of the same book, Delete the "water bridge" in lines 17-18.

(6) On page 5, line 9 of the same oath, add "in order to process" after "therefore". is the melting peak CC determined by differential thermal analysis)
'r, ψ represent the density based on JIS K6760] Polyethylene/From 7i: Nito 7 Hunter Detective and Ding^Bo 1 No Ethylene Pipe

Claims (1)

[Claims] mp>500Xψ-345 [However, mp is the melting peak (C) determined by differential thermal analysis.
, ψ represents the density based on JIS K 6760 Ni] A polyethylene pipe characterized by being made of water-crosslinkable polyethylene.