JPH01234452A - Radiation-resistant rubber composition - Google Patents

Abstract

PURPOSE:To obtain the title composition which is suitably used as a sheath for cables in atomic power plants, because of its excellent radiation resistance and mechanical characteristics, by adding halogenated acenaphthylene (polymer), magnesium oxide and others to chlorosulfonated polyethylene rubber. CONSTITUTION:100 pts.wt. of chlorosulfonated polyethylene rubber are combined with more than 10 pts.wt., preferably 15-45 pts.wt. of halogenated acenaphthylene (polymer) of the formula (X is H, C1 or the like: Y is C1, Br; R is substituent other than halogen; m is 2-6; n is 0-4 wherein m+n<=6), 3-30 pts.wt. of at least one or their mixture selected from magnesium oxide, calcium hydroxide, epoxy resin and others. Then, sulfur, sulfur compound or organic oxide, carbon black, inorganic filler, softening agent and antioxidant agent are added to the compound and they are vulcanized.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a radiation-resistant rubber composition, and is particularly suitable for a composition for a cable sheath used in nuclear power plants, spent nuclear fuel reprocessing facilities, etc. It is something.

(Prior art) Chlorosulfonated polyethylene rubber compositions with excellent radiation resistance are used in the sheaths of cables used in nuclear power plants, etc., but in recent years these compositions have been developed with even higher radiation resistance. Cables are often stretched and bent, especially in locations such as spent nuclear fuel reprocessing, and cables are often stretched and bent.
Flexibility is required even after exposure to 00 Mrad of radiation.

The present inventors previously found that rubber and plastic compositions using halogenated acenaphthylene and its polymers exhibit excellent radiation resistance and flame retardancy, and filed a patent application for this (Japanese Patent Application Laid-Open No. 59-31509). Publication No. 59-31513
(see publication).

[Problem to be solved by the invention]

The inventors continued their research in order to develop a radiation-resistant and flame-retardant cable using the above composition, and found that among the rubber compositions using the above halogenated acenaphthylene or its polymer, it was possible to use it for a sheath. It has been discovered that the preferred chlorosulfonated polyethylene rubber compositions have serious problems. That is, an electric wire sheathed with a composition containing lead metal oxide, which is most commonly used as an acid acceptor during vulcanization of a chlorosulfonated polyethylene rubber (hereinafter abbreviated as C8M) composition, is continuously heated by steam or dry heating. When vulcanization is performed using a commonly used heat vulcanization method, such as vulcanization or lead-coated vulcanization, the mechanical strength of the obtained sheath crude product is weak and its strength is low. The appearance also shows blisters and foaming, and has no commercial value.

(Means for Solving the Problem) In view of this, as a result of various studies, the present invention has found that even when halogenated acenaphthylene or its polymer is blended into a C3M composition and heat vulcanization is performed, the mechanical strength is high and the sheath surface We have developed a radiation-resistant rubber composition with a good appearance.

That is, the present invention provides a rubber composition in which sulfur, a sulfur compound, or an organic oxide, carbon black, an inorganic filler, a softener, and an antiaging agent are added to C3M and vulcanized. , at least one halogenated acenaphthylene or a polymer thereof
0 parts by weight, magnesium oxide, calcium hydroxide.

It is characterized in that 3 to 30 parts by weight of either one or a mixture of epoxy resin and hydrotalcite is added.

[For production]

In the present invention, C3M is a polymer obtained by reacting polyethylene with chlorine and sulfur dioxide gas, and any commercially available polymer may be used, but in particular Hypalon 4° (trade name) manufactured by DuPont. and TO3O manufactured by Tosoh Corporation
-C3)f A material having a chlorine content of 35%, such as TS530 (trade name), is desirable because it has excellent mechanical properties, extrusion processability, etc.

In addition, halogenated acenaphthylene or its polyisomer is a general formula in which X represents a hydrogen, chlorine or bromine atom, Y represents a chlorine or bromine atom, R represents a substituent other than a halogen atom, and m
is an integer of 2 to 6, n is an integer of 0 to 4, and m0n≦6
When n≧2, R may be the same or different groups.

The multimer is composed of halogenated acenaphthylene represented by the above formula, and is condensed by dehydrogenation or dehydrohalogenation reaction, and the degree of condensation is 2.
It means a multimer of the above.

Bonding points between the halogenated acenaphthylene structural units include, for example, those that can be easily formed, and those with a bonding degree of 3 or more can be considered to be obtained by increasing the number of structural units through any of these bonds. If the degree of condensation is 10 or more, the dispersibility in the composition will decrease, which is not preferable.

The amount of these halogenated acenaphthylenes is CS
It is preferably 10 or more parts by weight per 100 parts by weight of M, and preferably 15 to 45 parts by weight. However, if the amount is less than the above-mentioned 10 layers, it is difficult to meet the flame retardance required for cables for nuclear power plants or reprocessing plants, which is particularly intended in the present invention.

Combining other flame retardants may improve the original flame retardancy in some cases, but it is not preferable because it causes a decrease in tensile properties.

If such a combination is necessary, it is desirable to use the same amount or less of the halogenated acenaphthylene.

Next, the present invention is characterized in that 3 to 30 parts by weight of any one of magnesium oxide, calcium hydroxide, Epoquin resin, hydrotalcite, or a mixture thereof is used in place of the lead metal hydride as an acid acceptor. The vulcanization inhibition is improved only when these are blended, and even when the composition coated as a sheath is heated and vulcanized by the usual method, a composition that does not foam or blister and has high mechanical properties can be obtained. can get. However, if the amount of these substances is less than 3 parts by weight, it will not be effective as an acid acceptor and the vulcanization reaction will not proceed effectively, and if more than 30 parts by weight is added, the mechanical properties will deteriorate.

As the sulfur or sulfur compound used in the present invention, JIS
Rubber powder sulfur chloride, morpholuc disulfide, etc. specified in K 6222, and organic sulfur compounds such as dipentamethylenethiuram tetrasulfide, dipenzothiazyl disulfide, etc. are preferable.

These are used by adding about 0.5 to 3 parts by weight to 100 parts by weight of C3M. Also, tetramethylolmethane and °N-N
It is more preferable to add '-m-phenylene dimaleimide or the like.

Examples of organic compounds used in the present invention include dicumyl peroxide, 1,3-bis(t-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di(t-butylperoxyisopropyl)benzene,
-butylperoxy)hexyne.

3. t-butylcumyl peroxide, etc., and its blending amount is 0.8 to 10 parts by weight per 100 parts by weight of C3M, and these amounts crosslink C3M to achieve desired mechanical properties and thermal deformation. This is the amount necessary to obtain sex, etc.

Further, in the present invention, from the viewpoint of mechanical properties of the composition, it is preferable to add an inorganic filler such as calcium carbonate, talc, or clay, or a reinforcing agent such as carbon black. Moreover, various softeners can be added as viscosity modifiers of the composition, and various anti-aging agents can be added as heat resistance imparting agents.

〔Example〕

Examples will be described to explain the effects of the present invention in more detail.

A mixture having the composition shown in Table 1 was kneaded in a Banbury mixer to obtain a rubber composition. This was extruded and coated as a sheath on a cable coated with EP rubber as an insulator, and then heated and vulcanized. The vulcanization conditions include using a molten salt bath containing sodium nitrate, potassium nitrate, and sodium nitrite as the main components.
Nitrogen gas was loaded at 3/cr/ to 7, and vulcanization was performed at 190° C. for 3 minutes.

The surface of the sheath of the electric wire thus obtained was visually observed to see if there were any blisters or bubbles. In addition, samples were taken from the sheath and subjected to a tensile test according to JIS K 6301 to measure mechanical properties. These results are also listed in Table 1.

Furthermore, regarding the radiation resistance of the obtained electric wire, C
After irradiation with gamma rays from an o-60 radiation source, samples were similarly sampled from the sheath, subjected to a tensile test, and judged based on the magnitude of elongation characteristics.

As a result, Comparative Example 18 in Table 1, in which brominated acenaphthylene was not added, had no radiation resistance at all with a residual rate of 0% compared to the elongation before irradiation at 300 Hrad irradiation, whereas brominated acenaphthylene had no radiation resistance at all. Each of the other examples and comparative examples in Table 1 in which 15 parts by weight or more of acenaphthylene was added had a residual rate of 20% or more with respect to the elongation before irradiation, regardless of whether an acid acceptor was added. It was confirmed that the radiation resistance was good.

In addition, C3M in Table 1 is TO3O-C3)lT made by Tosoh.
Resurge paste #2 made by Toyo Ink Co., Ltd. for S-530 and other ships, and MgO# made by Kyowa Kagaku Co., Ltd. for magnesium oxide.
150, Calvit manufactured by Ohmi Kagaku Co., Ltd. for calcium hydroxide, and Epicoat 82 manufactured by Shell Chemical Co., Ltd. for epoxy resin.
8. DHT-4 manufactured by Kyowa Kagaku Co., Ltd. for hydrotalcite
A. For sulfur, use JIS 6220 powdered sulfur for rubber, for dipentamethylene thiuram tetrasulfide, use Tsukusela TRA manufactured by Iriuchi Shinko Kagaku Co., Ltd. For dibenshizothiazyl sulfide, use Tsukusela DH and tetramethylol manufactured by Iruuchi Shinko Kagaku Co., Ltd. Neulyzer P manufactured by Nippon Gosei is used for methane, and DCP manufactured by Nihon Yushi is used for dicumyl peroxide.
-R, carbon black is Asahi #70 manufactured by Asahi Carbon Co., Ltd.
-L, the inorganic filler (talc) is Mistron paper talc manufactured by Nippon Mistron Co., Ltd., and the softener (aromatic process oil) is JSOARO) IA manufactured by Nippon Sun Oil Co., Ltd.
790.

For the anti-aging agent (dibutyldithiocarbamine nickel), use Tsukuraku MBC manufactured by Iriuchi Shinko Kagaku Co., Ltd. For the condensate of halogenated acenaphthylene (condensate of brominated acenaphthylene), use one with a degree of condensation of 3 to 5 and a bromine content of 65%. there was.

As is clear from Table 1, sheaths (Examples Nα1 to 11) in which radiation resistance was imparted by heating and vulcanizing the composition of the present invention
It can be seen that the sheath has excellent mechanical properties similar to the normal sheath without radiation resistance (Comparative Example Nα18) in which no brominated acenaphthylene condensate is added, and the sheath appearance also shows that no foaming or blistering occurs.

On the other hand, sheaths that do not contain any one of magnesium oxide, calcium hydroxide, Epoquine resin, and hydrotalcite (Comparative Examples Nα12 to 17) have poor mechanical properties, and the appearance of the sheath is Foaming or blistering occurs. Also magnesium oxide, calcium hydroxide.

No foaming or blistering was observed in the sheaths containing more than 30 parts by weight of either epoxy resin or hydrotalcite, or a mixture thereof (Comparative Examples Nα19 to 21), but the mechanical properties were poor. I understand.

〔Effect of the invention〕

According to the present invention, in imparting radiation resistance by adding halogenated acenaphthylene or its polymer to C3M, any one of magnesium oxide, calcium hydroxide, epoxy resin, and hydrotalcite or a mixture thereof can be added to C3M. By adding an appropriate amount of , it has high mechanical properties and a good appearance on the sheath surface, and can be used as a sheath for cables used in places such as nuclear power plants and spent nuclear fuel reprocessing facilities. This has a remarkable effect.

Claims (1)

[Claims] (1) Sulfur in chlorosulfonated polyethylene rubber,
In a rubber composition that is vulcanized by adding a sulfur compound or an organic oxide, carbon black, an inorganic filler, a softener, and an anti-aging agent, halogenated acenaphthylene or its polymer is added to 100 parts by weight of chlorosulfonated polyethylene rubber. at least 10 parts by weight of magnesium oxide,
A radiation-resistant rubber composition characterized in that 3 to 30 parts by weight of any one or a mixture of calcium hydroxide, epoxy resin, and hydrotalcite are added.