JPS5865387A - Hot-water supply 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 The present invention relates to a hot water supply pipe used for supplying and distributing hot water, heat exchanger, etc. in ordinary homes, buildings, factories, hot spring resorts, and the like.

Currently, steel pipes are exclusively used as hot water pipes for general households and buildings, and steel pipes are extremely expensive and gradually corrode due to the chlorine compounds added to the water for sterilization. There are also problems.In addition, in hot spring areas, copper pipes are used to withdraw hot spring water and supply hot water.
Because it corrodes and ruptures after a very short period of use, FRP pipes without corrosion are currently used, but these pipes are brittle and easily break, so the damaged part of the pipe must be partially repaired. Currently, it is being used while being repaired.

Polyolefins, especially crosslinked polyolefins, have corrosion resistance-
This is excellent, and it is much more flexible than FRP.
Because of their Zen-like properties, pipes made of these materials seem promising for general hot water supply and hot spring water supply at hot spring areas.

However, if polyolefin pipes are used for long periods of time under internal pressure, brittle fracture of the pipes will rapidly progress or begin to develop.
), it takes a relatively short time to reach the knee point, but it has the drawback that it cannot be used with confidence. In general, the time it takes to reach the knee point is shorter as the water temperature increases; for example, for polyethylene pipes, the water temperature
In the case of "C", it is about 18 years, and if the water temperature is 80'C, it is about 2 weeks.

On the other hand, the knee point of crosslinked polyolefin pipes is extremely long, over several decades, and there is no need to consider the knee point problem. By the way, it has been discovered from research on the suitability of polyethylene pipes crosslinked with an organic peroxide crosslinking agent as hot water supply pipes that when crosslinking polyethylene with an organic peroxide crosslinking agent, the peroxide is Since a large amount of 2 parts or more is used per part (1 liter B1 or less), the decomposition products of peroxide generated during cross-linking remain in the cross-linked polyethylene pipe, and hot water cannot be supplied using such a pipe. If this is done, the above-mentioned decomposition products will be eluted into the hot water, imparting a bad odor to the hot water, and this bad odor may continue to be a problem for a long time, so it cannot be used practically as a hot water supply pipe. No. “There is a big problem with pipes, especially when it comes to hot spring pipes.

In view of the above, the present inventors conducted various experiments in order to develop a hot water pipe that eliminates the above-mentioned drawbacks, and found that if a specific water-crosslinked polyolefin is used, the strength characteristic number The inventors have discovered that it is possible to obtain a hot water supply pipe that is excellent and does not produce a bad odor, and has completed the present invention as set forth in the above-mentioned patent claim am.

The organic peroxide used by the present inventors as component (C) does not act to directly crosslink the polyolefin as component (λ), but rather functions as an activator for the silane compound as component (-). Isn't it too much?

The amount used is very small, 0.5 parts or less, preferably 0.05 to 0.3 parts, per 100 parts (by weight) of component C), so there is practically no problem with bad odors, or After a short period of use, the odor will disappear. In addition, among the unreacted substances of component Cb), by-products from component (-) produced by the graft reaction between component (mountain) and component (1) (
Alcohols (mainly alcohols) can also cause bad odors, but component (b) used in the present invention or its graft reaction by-products are both volatile and foul-smelling.
When the pipe of the present invention is run-in for a short period of time, the problem of foul odor caused by precipitation from the inside of the pipe disappears. In addition, the preferred lid for the (-) component is: (-) component, per 100 parts, o,
os ~ 10 parts, especially 0.1 to 5 parts. The amount of the silanol condensation catalyst used as component cd) is 0.5 or less per 100 parts of component (a), preferably o, o o s to 0.3.
Since the amount of silanol condensation catalyst is very small, it does not substantially cause any bad odor, and therefore, known silanol condensation catalysts can be used.

For example, carboxylic acid salts such as dibutyltin dilaurate, stannous acetate, stannous octoate (caprylic acid 'JS-@), lead naphthenate, zinc caprylate, iron 2-ethylhexane and cobalt naphthenate, Examples include titanate esters such as tetrabutyl titanate, tetranonyl titanate, and bis(acetylacetonitrile) di-isopropyl titanate, and organometallic compounds such as xate compounds.

Among these combinations of ingredients, (@) component is polyethylene, (b) component is vinyltrimethoxysilane, (C) component is dicumyl peroxide, (ψ
When dibutyltin dilaure-1 is used as a component, it is most preferable as a reagent for use in the present invention because organic substances that cause malodors are most easily removed, and therefore the malodor is less likely to be dissolved.

In the present invention, "water-crosslinked polyolefin, pipe"
may be understood to mean either "water-crosslinked polyolefin pipe" or "water-crosslinkable uncrosslinked polyolefin pipe" (although the present invention does not apply to any of the above 7% That is, in the present invention, it may be put to practical use in the form of an uncrosslinked polyolefin pipe molded using a composition consisting of the above-mentioned components (for) to (for), or the pipe may be put to practical use. Cross-linking may be carried out with water prior to the cross-linking.In any case, it is preferable that the degree of cross-linking achieved is at least 20% in terms of gel fraction, particularly sufficient cross-linking of at least 50 ml.Form of the cross-linked polyolefin pipe When put into practical use in a pipe, it is natural that there is no knee point problem seen in the polyolefin pipe mentioned above, or if it is put into practical use in an uncrosslinked state to transport high-temperature, compressed water. However, there is still no melting at the knee point.The reason for this is that in the temperature range of around 100"C or below 100"C, the hot water flowing through the polyolefin pipe melts much earlier than the time it takes to reach the knee point of the pipe. , water cross-linking has progressed sufficiently,
This is because the quality changes to a crosslinked polyolefin pipe. For example, in the case of thick-walled or ioaw uncrosslinked polyethylene pipe, crosslinking can be completed in about 2 months by transporting hot water at 40"C, or in about 3 days by transporting hot water at 80"C. Even before the degree of crosslinking is reached, the knee point will be significantly extended as crosslinking progresses, and for this reason, there is no need to worry about brittle fracture.

The wall thickness of the pipe of the present invention is the inner diameter of the pipe, for example, l
In the case of Qgw, 2Qm, 50 cod, 100 fins, 400 sins,
respectively, 0.5-3m, 1-5fi, 3-1, Q
sw, 5 ml, 5 m, and about 15 to 50 TIuI is appropriate.

Examples 1 to 14 are crosslinked polyethylene pipes with an inner diameter of 50 ff and an outer diameter of 60 M, which are crosslinked using a mechanical peroxide crosslinking agent, and Examples 1 to 14 are comparative examples. This is a water-crosslinked polyolefin pipe with the same dimensions.

Table 1 shows the compositions of the compositions used in the construction of the crosslinked polyolefin pipes of Comparative Examples and Examples 1 to 14.

The water bridges of the pipes in the examples were all made at a temperature of 24°C at a temperature of 90°C.
This was done by immersing it in hot water for an hour.

The pipes of Comparative Examples and Examples were tested for the presence or absence of bad odors. The test method is as follows, and the test results are shown in Table v62 along with the pipe gel fraction.

The test method was as follows: First, fresh hot water at 80° C. was flowed through a pipe with a flow rate of 0.51/min for 1 day, 1 week, and 1 month through each pipe with an inner diameter of 501 mm and an outer diameter of 60 mm and a length of 3 m. Then, after a predetermined period of time, a part of the pipe is sampled and JIS K 6
762 6.5xj4 method (L, temperature is 80'C
) was used to prepare sample water for measuring odor concentration. The odor concentration test was conducted based on Section 9 of [Water Test Methods - 1978 Edition] supervised by the Water Supply and Environment Department, Environmental Sanitation Bureau, Ministry of Health and Welfare.

The odor concentration values listed in Table 2 are Odor #曵=200
71 (minimum amount of test water (ml) to detect odor).

As is clear from Table 2, in the comparative example, the odor concentration was 1
40.1 weeks after 40.1 months, 22 after 1 day, 1 or 2 after 1 day, and 1 week and 1 month in all examples. It is smaller than 1. Therefore, it will be understood that in the comparative example, the odor continues even after one month has passed, whereas in all the examples, almost no odor is generated after one week has passed.

Examples 1 to 14 are the pipes of Examples 15 to 28, which differ only in that they are in an uncrosslinked state.
Odor concentration was measured under the same conditions as in Examples 1 to 14, and substantially the same results as in Examples 1 to 14 were obtained. Moreover, the gel fraction of the pipe after one cycle was also the same as that of the corresponding Examples 1 to 14, respectively. Incidentally, Example 10 (gel fraction 32
%) knee point arrival time is more than 10 years.

(Continued from the 1st table) Note 1...Density R0,945g/d, Melt index 0.899710 Dispense 2---Density 0.90 f/cd, M
42. Of / 10 minutes polypropylene Note 3... Vinyl acetate content 10'%, density 0.
Ethylene-vinyl acetate copolymer Note 4 with a melt index of 93 fl/d and a melt index of 31/10 minutes...Specific gravity 0.8? , viscosity in Mooni (ML1
+4'100"C) 201 Ethylene-propylene-diene copolymer in which the third component is dicyclopentadiene Note 5... Density 0.89'/d, melt index 5 f/10 min ethylene - Propylene binary copolymer Note 6... Chlorine content 32%, specific gravity 1.15. Chlorinated polyethylene with melt index 0.49/10 minutes Note 7... Density 110. 938f/14.Mel, polyethylene note 8 with a tondex of 0.259710 minutes.
...Dicumyl peroxide note 9 ...1
．． 3-bis-(1-butyl)g-oxy-inpropyl)-benzene Note 1O...2.5-dimethyl-2,5-di([
Butyl liver oxy)-hexyne-3 Attention...[-butylcumyl peroxide Note 1
2...-4.4'-di((-butylc-oxy)valeric acid n-phthyl ester)

Claims (4)

[Claims] (1), (a) polyolefin, and (b) one selected from the group consisting of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltridimethoxysilane, and vinyl-tris(β-methoxy-ethoxy)silane, or 21111 [The above silane compound, (C) dicumyl peroxide, 2,5-dimethyl-2
,5-di(t-butylnof-oxy)-hexyne-3
, 1,3-bis-(t-butyl-oxy-isopropyl)-benzene, t-butylcumyl oxide, 4,4'-di(t-butyl/oxy)valeric acid n-butyl ester and l , 1-di(1-butylperoxy)-3,3,5-trimethylcyclohexane, and (d) a silanol combination catalyst. A hot water supply pipe characterized in that it is made of a water-crosslinked polyolefin pipe formed using a water-crosslinked polyolefin pipe. (2) (@) Polyolefins consist of polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-propylene-diene terpolymer copolymer copolymer, ethylene-propylene binary copolymer rubber, and basic polyethylene. The hot water supply pipe according to claim 1, which is one type selected from the group or a mixture with a length of 2 m or more. (3) (@) A patent claim in which the polyolefin is polyethylene, (b) the silane compound is vinyltrimethoxysilane, (C) the compound is dicumyl peroxide, and (the silanol combination catalyst is dibutyl dilaurate) Hot water pipes listed in Section (]) or Section (2) of the IM section. □ (4) The hot water pipe according to any one of claims (1) to (3), wherein the pipe is for hot springs.