JPH10182756A - Polyolefin resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition comprising a polyolefin resin, a specific organic unsaturated silane, a free radical-generating agent, and a silanol condensation catalyst in specific amounts, respectively, and capable of giving crosslinked polyolefin resin reduced in its characteristic smell. SOLUTION: This composition comprises (A) 100 pts.wt. of a polyolefin resin, (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, the same as Y) (e.g. vinyltrimethoxysilane, allyltriethoxysilane), (C) 0.01-1 pt.wt. of a free radical-generating agent [e.g. 2,5-dimethyl-2,5-di(t-butylperoxy)hexane], and (D) 0.01-1 pt.wt. of a silanol condensation catalyst (e.g. odorless zinc stannate or hydroxy zinc stannate). Large improvements in work environments and practical use environments can thereby be expected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin which significantly reduces the odor peculiar to a crosslinked polyolefin resin which is generated at the time of molding or when it is actually used after molding, and which greatly improves the working environment and the actual use environment. It relates to a composition.

[0002]

2. Description of the Related Art As a simple method for cross-linking a polyolefin such as polyethylene, a polysilane is grafted with an organic unsaturated silane in the presence of a free radical generator, followed by silane grafting. The so-called silane crosslinking method of crosslinking by contact with moisture in the presence of a catalyst (for example, JP-B-48-1711, JP-A-57-49109, etc.) is compared with chemical crosslinking by organic peroxide or radiation-induced crosslinking. Because they are much simpler, they have become widespread in applications such as electric wires, cables, sheets, and pipes.

[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 such as water supply and hot water supply pipes that directly touch the molded product into the human mouth.

[0004]

DISCLOSURE OF THE INVENTION The present invention has solved these problems, and has remarkably reduced the odor peculiar to a crosslinked polyolefin resin which is generated during molding or when actually used after molding. It is intended to provide a resin composition in which the actual use environment is significantly improved.

[0005]

According to the present invention, there is provided a compound of the general formula RR'SiY ₂ (R is 1 to 100 parts by weight of a polyolefin resin).
Olefinic unsaturated hydrocarbon group, Y is a hydrolyzable organic group, and R 'is a monovalent hydrocarbon group other than aliphatic unsaturated hydrocarbon or the same as Y). 1 to 5 parts by weight, free radical generator 0.01 to 1
The resin composition contains 0.01 to 1 part by weight of a silanol condensation catalyst. 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. It is a resin composition that is zinc acid.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The component (a) of the present invention is a polyolefin resin as a base of a resin composition. These polyolefin resins include high-density polyethylene, medium-density polyethylene, low-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer, and ethylene-propylene-diene ternary. One or more resins selected from copolymers, hydrogenated derivatives of styrene-butadiene-block copolymers, hydrogenated derivatives of styrene-isoprene-block copolymers and the like are used.

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 and the like can be mentioned. The amount of these additives is 1 to 5 parts by weight, preferably 1.5 to 3.5 parts by weight, based on 100 parts by weight of the base polymer. When the amount is less than 1 part by weight, sufficient grafting does not occur, and when the amount is more than 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. As these organic peroxides, 2,5-dimethyl-2,5-di (t-
Butylperoxy) hexane, α, α'-bis (t-butylperoxy-m-isopropyl) benzene, di-t
One or more organic peroxides selected from -butyl peroxide, di-t-butyl peroxyisophthalate and the like are used.

The decomposition temperature for obtaining a half-life of 1 minute is 1
Below 70 ° C, the reaction becomes intense and difficult to control,
At 250 ° C. or higher, 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. Component (c) is added in an amount of 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. When the amount is less than 0.01 part by weight, a sufficient silane grafting reaction does not proceed. When the amount is more than 1 part by weight, the extrudability decreases and the molding surface deteriorates.

The component (d) of the present invention acts as a silanol condensation catalyst for crosslinking 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
When the amount is less than 1 part by weight, a sufficient silanol condensation reaction of the silane graft mer does not proceed, and when the amount is more than 1 part by weight, extrudability deteriorates.

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. <Examples 1 to 4 and Comparative Examples 1 to 9> A base polymer, an organic unsaturated silane and a free radical generator are mixed according to the grafting compound ratio as shown in Tables 1 and 2, and a single screw extruder is used. The mixture was kneaded at an extrusion temperature of 120 to 280 ° C, and was strand-cut and granulated to obtain a silane graftmer. Next, the base polymer, the silane condensation catalyst, and the antioxidant are mixed according to the catalyst master batch mixing ratio as shown in Tables 1 and 2, and the mixture is kneaded using a single screw extruder at an extrusion temperature of 120 to 230 ° C. The resultant was cut and granulated to obtain a catalyst master batch.

The obtained silane graft mer and the catalyst masterbatch are mixed according to the mixing ratios shown in Tables 1 and 2, and kneaded using a single screw extruder to have an outer diameter of 15 mm and a thickness of 1.5 m.
After being extruded into a tube having a length of m, a crosslinking treatment was performed by immersing the tube in warm water. Using this tube-shaped sample, the evaluation of the appearance, the hygiene test and the evaluation of the odor were performed.
Further, a test specimen for a tensile test was prepared from this tubular sample, and a tensile test was performed.

The evaluation results are shown in Tables 1 and 2.

[Table 1]

[0016]

[Table 1]

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) Appearance: Appearance of extruded tube Evaluation Excellent>good>acceptable> not acceptable, 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

As is clear from Tables 1 and 2, the materials shown in Examples 1 to 4 maintain strength, and have good odor and good 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, which used conventional dicumyl peroxide as a free radical generator, had a strong pungent odor. In Comparative Example 6, in which the amount of the free radical generator added was small, the silane grafting reaction did not proceed sufficiently, so that the silane odor was strong and the strength was small. 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 the amount of added silane was large, excess silane was left unreacted, and the silane smell was sharp and the appearance was poor.

[0021]

According to the present invention, the odor peculiar to a crosslinked polyolefin resin which is generated at the time of molding or when actually used after molding is significantly reduced, and the working environment and the actual use environment are greatly improved. A composition can be obtained.

Claims (3)

[Claims] 1. A composition comprising the following components (a) to (d), wherein (b) is 1 to 5 parts by weight and (c) is 0.1 to 100 parts by weight of (a). 0.01 to 1 part by weight and 0.01 to 1 parts by weight of (d)
A resin composition characterized by containing by weight. (a) Polyolefin resin. (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 free radical generator according to claim 1, wherein the decomposition temperature for obtaining a half life of 1 minute is 170 ° C. or more and 250 ° C. or less, and the amount of active oxygen is 8% or more.
The resin composition as described in the above. 3. The resin composition according to claim 1, wherein the silanol condensation catalyst is zinc stannate or zinc hydroxystannate.