JPH10182757A - Pipe for supplying water or hot water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject pipe remarkably reduced in the characteristic smell of a crosslinked polyolefin resin by using a resin composition comprising a high density polyethylene, an organic unsaturated silane, a free radical- generating agent, and a silanol condensation catalyst. SOLUTION: This pipe comprises a resin composition comprising (A) 100 pts.wt. of a high density polyethylene, (B) 1-5 pts.wt. of an organic unsaturated silane of the formula: RR'SiY2 (R is a monovalent unsaturated hydrocarbon; Y is a hydrolyzable organic group; R' is a monovalent hydrocarbon except aliphatic unsaturated hydrocarbons, etc.) (e.g. vinyltrimethoxysilane, (C) 0.01-1 pt.wt. of a free radical-generating agent (preferably an agent having a decomposition temperature of 170-250 deg.C for obtaining a half life of 1min and having an active oxygen amount of >=8%) and (D) 0.01-1 pt.wt. of a silanol condensation catalyst (e.g. zinc stannate or hydroxy zinc stannate). The pipe has a potassium permanganate consumption amount of <=2mg/L.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water supply in which the odor peculiar to a crosslinked polyolefin resin, which is generated at the time of molding or is actually used after molding, is significantly reduced, and the working environment and the actual use environment are greatly improved. It relates to a hot water supply pipe.

[0002]

2. Description of the Related Art Conventionally, a steel pipe or a reinforced rubber pipe has been used as a water supply / hot water supply pipe. However, a metal tube has a problem of rust, and a rubber tube has a problem that molding processing is not easy. Therefore, crosslinked polyethylene has been used. As a simple method of crosslinking polyethylene,
A so-called silane cross-linking method (hereinafter referred to as a silane cross-linking method) in which the polyethylene is grafted with an organic unsaturated silane in the presence of a free radical generator to effect silane grafting, and then the silane grafter is contacted with water in the presence of a silanol condensation catalyst to cross-link. For example, JP-B-48-1711, JP-A-57-49109, etc.) are much simpler than chemical crosslinking and radiation-irradiation crosslinking with organic peroxides, and therefore, electric wires, cables, sheets, pipes, etc. It has become widespread in applications.

[0003] However, these materials have peculiar irritating odors and fatty acid odors, and at the time of molding, these odors spread in the building where the molding machine is installed, resulting in a deterioration of the working environment, and workers are unpleasant odors. You have to work inside. In addition, since these odors remain in the molded product itself, it cannot be used in applications in which objects that touch the molded product, such as water supply and hot water supply pipes, directly enter the human mouth.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve these problems. The present invention significantly reduces the odor peculiar to crosslinked polyethylene, which is generated at the time of molding or when actually used after molding. The purpose is to provide a hot and cold water supply pipe with greatly improved use environment.

[0005]

The hot water supply pipe of the present invention is a resin composition comprising the following components (a) to (d):
(b) is contained in 1 to 5 parts by weight, (c) is contained in 0.01 to 1 part by weight, and (d) is contained in 0.01 to 1 part by weight with respect to 100 parts by weight of (a). (a) High density polyethylene. (b) General formula RR'SiY ₂ (R is a monovalent olefinically unsaturated hydrocarbon group, Y is a hydrolyzable organic group, R 'is a monovalent hydrocarbon group other than aliphatic unsaturated hydrocarbon or Y The same as above)). (c) A free radical generator having a decomposition temperature of 170 ° C. or more and 250 ° C. or less and an active oxygen content of 8% or more for obtaining a half-life of 1 minute. (d) a silanol condensation catalyst which is zinc stannate or zinc hydroxystannate. In a further preferred embodiment, the free radical generator has a decomposition temperature of 170 ° C. or more and 250 ° C. or less and an active oxygen content of 8% or more for obtaining a half-life of 1 minute, and the silanol condensation catalyst is zinc stannate or hydroxytin. The hot water supply pipe is made of zinc oxide, and has a potassium permanganate consumption of 2 mg / L or less.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The component (a) of the present invention is a base of a resin composition and must be a high-density polyethylene in order to maintain sufficient strength. One type of resin may be used alone, or two or more types of resins may be used in combination.

The component (b) of the present invention is to be grafted onto the base resin so as to be a cross-linking point between the base resins. The organic unsaturated silane used in the present invention is represented by the general formula RR'SiY ₂ (R is a monovalent olefinically unsaturated hydrocarbon group, Y is a hydrolyzable organic group, and R 'is an aliphatic unsaturated hydrocarbon. Other monovalent hydrocarbon groups or the same as Y) are used. It is desirable to use an organic unsaturated silane represented by the general formula RSiY _{3 wherein} R ′ is the same as Y, for example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltributoxysilane, allyltrimethoxysilane, allyltriethoxysilane. Examples include silane. The amount of these additives is as follows.
1 to 5 parts by weight, preferably 1.5 to 5 parts by weight with respect to 0 parts by weight
3.5 parts by weight. If the amount is less than 1 part by weight, sufficient grafting does not occur, and if it exceeds 5 parts by weight, molding failure occurs and it is not economical.

The component (c) of the present invention functions as an initiator for a silane graft reaction. The free radical generator used in the present invention has a decomposition temperature of 170 ° C. or more and 250 ° C. or less and an active oxygen content of 8% or more for obtaining a half-life of 1 minute. Various organic peroxides that do not produce a pungent odor are used. These organic peroxides include 2,5-dimethyl-2,5-di (t
-Butylperoxy) hexane, α, α'-bis (t-
Butylperoxy-m-isopropyl) benzene, di-
One or more organic peroxides selected from t-butyl peroxide, di-t-butyl peroxyisophthalate and the like are used.

The decomposition temperature for obtaining a half-life of 1 minute is 1
If the temperature is lower than 70 ° C., the reaction becomes intense and the control is difficult.
If the temperature exceeds 250 ° C., no reaction occurs under appropriate conditions. If the amount of active oxygen is less than 8%, it is necessary to add a large amount of a free radical generator, resulting in poor appearance and reduced strength. The amount of these additives is 0.01 to 1 part by weight, preferably 0.03 to 0.3 part by weight, based on 100 parts by weight of the base polymer. If the amount is less than 0.01 part by weight, a sufficient silane grafting reaction does not proceed. If the amount exceeds 1 part by weight, the extrudability decreases and the molding surface deteriorates.

The component (d) of the present invention functions as a silanol condensation catalyst which crosslinks the silane grafter under contact with moisture. As the silanol condensation catalyst used in the present invention, one or two kinds selected from zinc stannate and zinc hydroxystannate, which are odorless inorganic tin compounds, instead of conventional organic tin compounds having a fatty acid odor. One or more silanol condensation catalysts are used. The amount of these additives is 0.01 to 1 part by weight, preferably 0.03 to 0.3 part by weight, based on 100 parts by weight of the base polymer. 0.0
If the amount is less than 1 part by weight, a sufficient silanol condensation reaction of the silane grafter does not proceed, and if it exceeds 1 part by weight, the extrudability deteriorates.

As a hygiene test of the water supply hot water supply pipe of the present invention, potassium permanganate consumption is 2 mg / L or less. If the consumption of potassium permanganate exceeds 2 mg / L, it cannot be used as a pipe for water supply or hot water supply. The test for potassium permanganate consumption was conducted according to JIS K676.
9 was performed.

As other additives, the resin composition of the present invention may optionally contain commonly used additives such as antioxidants, neutralizers, ultraviolet absorbers, antistatic agents, pigments, dispersants, lubricants, Viscous agents, foaming agents, metal deterioration inhibitors, fungicides, flow regulators, etc., and flame retardants of phosphorus and phosphine derivatives, other inorganic fillers, crosslinking agents, crosslinking aids, etc.
Alternatively, another synthetic resin can be contained.

[0013]

Embodiments will be described below with reference to embodiments. According to the mixing ratio as shown in Tables 1 and 2, the base polymer, the organic unsaturated silane and the free radical generator are mixed,
Using a single-screw extruder, the mixture was kneaded at an extrusion temperature of 120 to 280 ° C, and then strand-cut and granulated to obtain a silane graftmer. Further, according to the mixing ratio shown in Tables 1 and 2, the base polymer, the silane condensation catalyst and the antioxidant were mixed, and kneaded at an extrusion temperature of 120 to 230 ° C. using a single screw extruder.
The strand was cut and granulated to obtain a catalyst master batch. The obtained silane graft mer and the catalyst master batch were mixed according to the mixing ratios shown in Tables 1 and 2,
The mixture was kneaded using a single screw extruder, extruded into a tube having an outer diameter of 15 mm and a thickness of 1.5 mm, and then subjected to crosslinking treatment by immersion in warm water. Using this tubular sample, the appearance was evaluated, and the consumption of potassium permanganate and the smell, which were hygiene tests, were evaluated. Further, a test specimen for a tensile test was prepared from this tubular sample, and a tensile test was performed.

The resins used in the examples and comparative examples are as follows. (1) Polyolefin resin: high-density polyethylene; Showrex S4503FD (manufactured by Showa Denko KK) (2) Organic unsaturated silane: vinyltrimethoxysilane; silane
SB6301 (Shin-Etsu Chemical Co., Ltd.) (3) Free radical generator 1: α, α′-bis (t-butylperoxy-m-isopropyl) benzene; para-butyl
P (manufactured by NOF Corporation) (Decomposition temperature for obtaining a half-life of 1 minute; 175 ° C, active oxygen content: 8.9%) (4) Free radical generator 2: 2,5-dimethyl-2,5
-Di (t-butylperoxy) hexane; para-hexa 25B
(Manufactured by NOF CORPORATION) (Decomposition temperature for obtaining a half-life of 1 minute; 180 ° C, active oxygen content: 9.9%) (5) Free radical generator 3: dicumyl peroxide; percumyl D ( (Nippon Yushi Co., Ltd.) (Decomposition temperature for obtaining a half-life of 1 minute; 175 ° C., active oxygen content: 5.8%) (6) Lubricant: stearic acid (7) Silanol condensation catalyst 1: zinc stannate (Japan Chemical industry
(8) Silanol condensation catalyst 2: zinc hydroxystannate (manufactured by Nippon Chemical Industry Co., Ltd.) (9) Silanol condensation catalyst 3: dibutyltin dilaurate; Stan BL (manufactured by Sankyoki Gosei Co., Ltd.) (10) Antioxidant 1: pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-human phenylphenyl) fluorophosphate]; Dolphinox 1010 (manufactured by Nippon Chika Ikki Co., Ltd.) 11) Antioxidant 2: N, N'-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine; Dolphinox MD1024 (Nippon Tihaka Iki)
(Made by Corporation)

The evaluation was performed by the following method. (12) Tensile strength: According to JIS K6760. (13) Elongation: According to JIS K6760. (14) Smell: Smell of water after immersing a tubular molded article in water at 50 ° C for 24 hours. Evaluation Excellent>good>acceptable> unacceptable, and acceptable up to acceptable level. (15) According to JIS K6769. (16) Appearance: Appearance of the extruded tube Evaluation Excellent>Good>Positive> Not possible, and acceptable up to acceptable level. Extrusion conditions: 50mmφ single screw extruder 160-190-210-220-210-
210 ° C L / D: 22 Compression ratio 3.5 Tube die Outer diameter 15mm, Inner diameter 12
mm

[0016]

[Table 1]

[0017]

[Table 2]

As is clear from Tables 1 and 2, the materials shown in Examples 1 to 4 maintain strength and have good odor, hygiene and tube appearance. On the other hand, Comparative Examples 1 and 2 in which conventional dibutyltin dilaurate was used as a silanol condensation catalyst had a strong fatty acid odor. In Comparative Example 3 in which the addition amount of the silanol condensation catalyst was small, the strength was small because the silanol condensation reaction of the silane graftmer did not sufficiently proceed. In Comparative Example 4 in which the addition amount of the silanol condensation catalyst was large, a good appearance was not obtained and the strength was small.

Comparative Example 5 using conventional dicumyl peroxide as a free radical generator has a strong pungent odor. In Comparative Example 6 where the amount of the free radical generator added was small,
Since the silane grafting reaction has not sufficiently proceeded, the silane odor is sharp, good hygiene cannot be obtained, and the strength is low. In Comparative Example 7 in which the amount of the free radical generator was large, a good appearance was not obtained and the strength was small. In Comparative Example 8 in which the amount of silane added was small, the strength was small because the silane grafting reaction did not proceed sufficiently. In Comparative Example 9 in which a large amount of silane was added, excess silane was left unreacted, so that the silane smell was sharp, good hygiene was not obtained, and the appearance was poor.

[0020]

According to the present invention, there is provided a resin composition which significantly reduces the odor peculiar to crosslinked polyethylene which is generated during molding or when actually used after molding, and which greatly improves the working environment and the actual use environment. The resulting hot and cold water supply pipe can be obtained, and it is odorless and sanitary.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29K 23:00 105: 24 B29L 23:00

Claims (4)

[Claims] (1) It comprises the following components (a) to (d), and (a) 1
(B) is 1 to 5 parts by weight, and (c) is 0.0
A hot water supply pipe comprising a resin composition containing 1 to 1 part by weight and 0.01 to 1 part by weight of (d). (a) High density polyethylene. (b) General formula RR'SiY ₂ (R is a monovalent olefinically unsaturated hydrocarbon group, Y is a hydrolyzable organic group, R 'is a monovalent hydrocarbon group other than aliphatic unsaturated hydrocarbon or Y The same as above)). (c) Free radical generator. (d) Silanol condensation catalyst. 2. The method according to claim 1, wherein the free radical generator has a decomposition temperature of 170 ° C. or more and 250 ° C. or less and an active oxygen content of 8% or more for obtaining a half life of 1 minute. Hot water supply pipe. 3. The hot water supply pipe according to claim 1, wherein the silanol condensation catalyst is zinc stannate or zinc hydroxystannate. 4. The hot water supply pipe according to claim 1, wherein potassium permanganate consumption of the hot water supply pipe is 2 mg / L or less.