JPH02166135A - Polychloroprene rubber composition - Google Patents

Abstract

PURPOSE:To obtain a polychloroprene rubber composition excellent in oil and chemical resistances and desirable for a self-shrinking tube material having rubber elasticity by adding a vulcanizer and other adjuvants to a matrix prepared by mixing polychloroprene rubber with a softener and carbon black. CONSTITUTION:A matrix is prepared by mixing 100 pts.wt. polychloroprene rubber with 10-80 pts.wt. at least one member selected from among an ester softener, an aromatic softener and a naphthenic softener and 10-100 pts.wt. carbon black of a mean particle diameter >=90mum. This matrix is further mixed with a vulcanizer, a vulcanization aid and other adjuvants. Although ZnO, MgO, PbO, Pb3O4, ZnCO3 or the like can be used as the vulcanizer, a combination of ZnO with MgO is desirable from the viewpoint of stability. As the vulcanization accelerator, any one of general ones used for chloroprene, such as thiourea, quanidine, thiuram and thiazole types can be used.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a polychloroprene rubber composition, and in particular,
The present invention relates to a rubber composition suitable as a raw material for self-shrinking tubes having rubber elasticity for conveniently protecting the connection parts of electric wires and cables.

(Prior Art) In recent years, elastic self-shrinking tubes that can be shrunk and covered without using heat have been used to cover or repair the connections of electric wires, cables, pipes, etc. for purposes such as irrigation, protection, and insulation. It is being This rubber-elastic self-shrinking tube is a rubber-elastic self-shrinking tube that is made of rubber-elastic tubes that are
Withstands elastic contraction force even when stretched and expanded by several hundred percent,
In addition, many of them are supported on a cylindrical support having sufficient strength to maintain the tube shape. For example,
As disclosed in Japanese Utility Model Publication No. 46190, a cylindrical support in which a seven-shaped groove is continuously provided on the outer peripheral surface in advance, or as disclosed in Japanese Utility Model Application Publication No. 121172/1983, A cylindrical plastic tube has a plurality of protrusions extending in the axial direction at intervals on the inner wall surface of the tube, and a continuous spiral cut is made in the wall surface along the entire length of the tube, and only the protrusions are made. It is supported by a cylindrical support for an elastic self-contracting tube that is directly connected to the
A method is generally used in which the support is removed at the time of use. Such elastic self-contracting tubes must be difficult to relax when supported in an expanded diameter state, that is, have low permanent deformation, and must not be cut in an expanded diameter state, that is, have high elongation and high tear strength. is an essential requirement. Ethylene propylene rubber is often used as a material for elastic self-shrinking tubes because of its excellent properties.

However, as usage methods have become more complex, applications that come into contact with oil and chemicals have increased, and it has become clear that the conventionally used elastic self-shrinking tubes based on ethylene propylene rubber deteriorate rapidly and are no longer usable. I came.

Therefore, as an alternative to these tubes, a new elastic self-shrinking tube that has good oil and chemical resistance and anticorrosive properties has been desired.

Materials with good oil and chemical resistance include chloroprene rubber, chlorosulfone polyethylene rubber, silicone rubber, and fluororubber, but among them, chloroprene rubber has a long track record of being used as an anti-corrosion material for electric wires and cables.
It is often used because it is inexpensive.

However, when an elastic self-shrinkable tube is manufactured from a general polypropylene rubber composition used for electric wires, cables, etc., and when it is supported with expanded diameter as described above and is actually used, the permanent deformation is too large. It was confirmed that it was not practical.

(Problems to be solved by the invention) The present invention solves these conventional problems and
The present invention aims to provide a polychloroprene rubber composition that has low permanent deformation and has excellent oil and chemical resistance, and is suitable for self-shrinking cable material having rubber elasticity to easily protect cable connections. be.

(Means for Solving the Problems) The polychloroprene rubber composition of the present invention contains one of an ester softener, an aromatic softener, a naphthenic softener, or A matrix containing 10 to 80 parts by weight of two or more types and 10 to 100 parts by weight of carbon black with an average particle size of 90 μm or more is used as a matrix, and in addition to the matrix, a vulcanizing agent, a vulcanization accelerator, and other additives are added. It is characterized by being made by adding and mixing an auxiliary agent.

The polychloroprene rubber used in the present invention is a polymer of chloroprene, 2-chloro-1,3-butadiene, and is a synthetic elastomer that is widely used commercially. Any commercially available products may be used, but especially neoprene WXK-
K (trade name of Showa Neoprene Co., Ltd.) is suitable.

As the softening agent for polychloroprene rubber in the present invention, dibutyl phthalate, di-n-octyl phthalate,
Any of ester-based materials such as diisooctyl phthalate and di(2-ethylhexyl) sebacate, petroleum-based naphthene-based materials, and aromatic-based materials may be used. However, in particular, the aromatic softener JSOAR
OMA 790 (trade name of Nippon Sun Oil Co., Ltd.) is suitable.

The reason why the amount of these softeners is limited to 10 to 80 parts by weight is that if it is less than 10 parts by weight, the elongation of the resulting mixture will be low, and if it exceeds 80 parts by weight, the adhesiveness of the mixture will be low. This is not possible because it will increase the amount of water and cause problems in the processability of mixing.

Next, the reason why carbon black is blended in the present invention is to increase tear strength, and the composition of the present invention can be achieved by using carbon black having an average particle size of 90 μm or more.

7. Using particles with an average particle size smaller than 901Ill+ will certainly increase the tear strength, but the reinforcing properties will be too strong.
Of course, when a tube is formed, the diameter expansion operation becomes difficult, but the elongation becomes small, and the diameter expansion magnification cannot be set very high. Examples of such carbon black include thermal furnace carbon, FT carbon, M
It is called T carbon black. MT carbon black is particularly good and is marketed as HUBER N-990 (trade name of HUBER Co., Ltd.).

The reason why the amount is limited to 10 to 100 parts by weight is that if it is less than 10 parts by weight, the tear strength will be weak, and if it exceeds 100 parts by weight, not only will the elongation decrease, but the permanent deformation will also decrease. Evil (Naru)

In the present invention, a mixture prepared by using the above compounding agents as a base and further adding the following compounding agents thereto is used after being vulcanized.

As a vulcanizing agent, ZnO, MgO, PbO+ Pb5O
a+ ZnCO3 etc. are used, but from the viewpoint of vulcanization stability, ZnO is used.

It is desirable to use both HgO in combination, particularly 15 parts by weight of Zn0 and 4 parts by weight of MgO.

As the vulcanization accelerator, any of those commonly used for chlorobrene, such as thiourea, guanidine, thiuram, and thiazole, can be used, but in particular, 1.5 parts by weight of trimethylthiourea, 0 parts by weight of dibenzothiazyl disulfide .5 parts by weight is preferred.

Next, as the anti-aging agent, any anti-aging agent used in chloroprene rubber can be used, but in particular, 2-mercaptobenzimidazole, a reaction product of diphenylamine and acetone, mixed diaryl-p
- A combination system of phenylenediamine is desirable, and the amount used is preferably 2 to 6 parts by weight.

In the present invention, processability or flame retardance can be improved by adding lubricants such as stearin and paraffin wax, and flame retardants such as antimony trioxide and decabromodiphenyl ether, if necessary.

Incidentally, even if the composition of the present invention is vulcanized with an opportunistic peroxide, the effects of the present invention will not be impaired.

(Example) Hereinafter, the present invention will be further explained with reference to Examples. All formulations shown in Table 2 are given in parts by weight. The contents of each example are summarized in the same table.

In Examples 1 to 5, each component was kneaded in a Banbury mixer to obtain a composition. Each of these compositions was put into a mold, and the molding temperature was 150″C1.
It was vulcanized for 15 minutes under a molding pressure of 150 kg/d to obtain a rubber tube with an inner diameter of 20 mm, a wall thickness of 1.5 mm, and a length of 150 square meters.

Further samples were taken from these tubes, and 200% was obtained using JIS 6301 dumbbells.
We looked at the permanent set characteristics after stretching and holding at 70" CCX for 72 hours. These data are based on 200% expansion of the original dimensions and looking at how much the original dimensions have expanded after release. This value The smaller the value, the more difficult it is to relax while the diameter is maintained in an expanded state.

In addition, the elongation properties at break and the tear strength using a Type B test piece were measured according to JISK 6301. In addition, as a typical example of oil resistance and chemical resistance, AST according to JISK 6302
Soaked in FINo 2 oil at 120°C for 18 hours,
The degree of swelling was observed before and after immersion. The same operation as above was also performed in comparative examples and conventional examples (general examples of chloroprene compositions for electric wires, ethylene propylene rubber compositions).

The general name, product name, and manufacturer of each component used in Examples, Comparative Examples, etc. are shown in Table 1.

(Effects of the Invention) As can be seen from the Examples and Comparative Examples, the Examples have good tear strength, permanent deformation, and oil resistance, but the Comparative Examples have poor properties. Furthermore, conventional chlorobrene formulations have poor permanent deformability, and ethylene propylene rubber has poor oil resistance.

As described above, according to the present invention, it is possible to obtain a polychloroprene rubber composition that has excellent oil resistance and chemical resistance (has an anticorrosion function), and has low relaxation (low permanent deformation).

Claims (1)

[Claims] 1. For 100 parts by weight of polychloroprene rubber, 10 to 80 parts by weight of one or more of ester softeners, aromatic softeners, and naphthenic softeners with an average particle size of 90 μm or more. A matrix containing 10 to 100 parts by weight of carbon black is added to the matrix, and a vulcanizing agent,
A polychloroprene rubber composition comprising a vulcanization accelerator and other auxiliary agents.