JPH0543743B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to sulfur vulcanizable halogen-containing ethylene-α-olefin copolymers, halogen-containing ethylene-α-olefin-nonconjugated diene copolymers (hereinafter propylene is the most representative α-olefin), halogenated EPM, halogenation
It relates to rubber compositions (abbreviated as EPDM). EPM and EPDM have excellent heat resistance, weather resistance, ozone resistance, etc., and are used in a wide range of applications. However, since it does not have a polar group in its polymer structure, it has a major drawback of poor oil resistance and organic solvent resistance. Therefore, in hoses, belts, and packing applications that require oil resistance, a method (blend) has been used in which oil-resistant rubbers such as acrylonitrile butadiene rubber (NBR) and chloroprene rubber (CR), which have excellent oil resistance, are used in combination. However, these methods include problems such as poor co-vulcanization and non-uniform dispersion of fillers, vulcanization accelerators, etc. On the other hand, many attempts have been made to improve oil resistance by introducing polar groups into EPM and EPDM. The most typical example is the introduction of halogen, and halogenated EPDM is widely known. However, halogenated EPDM is actually only used in limited applications as adhesives. The reason for this is that there was no technology that enabled iovulcanization. The most typical methods for crosslinking rubber are sulfur vulcanization and peroxide vulcanization, and sulfur vulcanization in particular allows for the crosslinking rate to be greatly adjusted by selecting and varying the vulcanization accelerator; However, it has the major feature that crosslinking progresses, and is used in a much wider range than peroxide vulcanization. Of course, depending on the type of rubber, peroxide vulcanization is the only option available, but many general-purpose rubbers, such as natural rubber, styrene-butadiene rubber (SBR), EPDM, and NBR, require peroxide vulcanization. However, sulfur vulcanization is much more common. The present inventors have studied methods for vulcanizing halogenated EPM and halogenated EPDM to enable this sulfur vulcanization, and have arrived at the present invention. The present invention provides halogenated EPM, halogenated
This relates to a sulfur-vulcanizable rubber composition using EPDM, and it goes without saying that it contains sulfur as a crosslinking agent, but it also contains a limited acid acceptor and a rubber composition for efficient crosslinking. Contains limited vulcanization accelerators. In order to vulcanize halogenated EPM and halogenated EPDM with sulfur, it is necessary to cause a dehalogenation reaction in the high temperature range (below the vulcanization temperature) where crosslinking occurs, but at this time acidic substances such as hydrochloric acid are released. .
For this purpose, an acid acceptor is required, and the present inventors have made sulfur vulcanization possible by selecting a limited compound, calcium oxide, as the acid acceptor. As acid acceptors for halogenated polymers such as CR and chlorinated polyethylene, metal oxides such as magnesium and lead, and hydroxides of these metals are widely known. Calcium hydroxide and calcium oxide are also known, but conventional halogenated polymers such as CR and chlorinated polyethylene have extremely low acid-accepting effects compared to the metal compounds mentioned above, and therefore cannot be put to practical use. Everything was close to nothing. The inventors have identified halogenated EPM, halogenated
As a result of intensive studies on the sulfur vulcanization method for EPDM, we found that the conventional method for vulcanizing these polymers was extremely effective.
They discovered that calcium oxide, which was thought to be present in small quantities, had very excellent effects. This is truly surprising. Of course, conventional acid acceptors such as lead monoxide and magnesium oxide can be used in combination with calcium oxide, but sufficient crosslinking cannot be achieved in the absence of calcium oxide, and the properties are insufficient. That is, the composition of the present invention requires calcium oxide. The composition of the present invention thus contains calcium oxide in an amount of 1 to 50 parts by weight, preferably 2 to 30 parts by weight, per 100 parts by weight of halogenated EPM or halogenated EPDM. If the amount is less than this, a sufficient effect will not be obtained, and even if the amount is increased beyond this, no effect will be seen. The amount of metal oxides such as magnesium and lead used as auxiliary acid acceptors if necessary is 1 to 50 parts by weight, generally 2 to 30 parts by weight. Furthermore, the present inventors have proposed that the vulcanization accelerator be selected from each of the groups (i) to (iii): (i) dithiocarbamates, (ii) thiurams, (iii) thiazoles and/or guanidines. It has been discovered that it is important to use one or more types of accelerators in combination. That is, sulfur vulcanization of halogenated EPM and halogenated EPDM requires a specific acid acceptor,
The present inventors have discovered that a practically satisfactory result can only be achieved by the two limitations of a specific combination of vulcanization systems. Dithiocarbamates alone, thiurams alone,
Practically satisfactory physical properties cannot be obtained by using only thiazoles or guanidine alone. Examples of dithiocarbamates include zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc di-n-butyldithiocarbamate, etc.
Tellurium diethyldithiocarbamate, etc., thiurams include tetramethylthiuram monosulfide, tetramethylthiuram disulfide, dipentamethylenethiuram tetrasulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, etc., and thiazoles Examples include 2-mercaptobenzothiazole, dibenzothiazyl disulfide, 2-mercaptobenzothiazole zinc salt, N-cyclohexyl-2-
Examples of the guanidines include benzothiazole sulfenamide and N-oxyethylene-2-benzothiazole, and examples of the guanidines include diphenylguanidine and diorthotolylguanidine. The accelerator selected from each group is 0.1 to 5.0 parts by weight, typically 0.2
Used in an amount of ~3.0 parts by weight. Further, 0.5 to 30 parts by weight of zinc stearate, which has an active effect, is added as necessary. In the present invention, halogenated EPM and halogenated EPDM include chlorine, bromine,
It contains halogens such as fluorine, but most commonly contains chlorine and both chlorine and bromine. The content of these halogens is adjusted to be 1 to 50% by weight, preferably 3 to 40% by weight. These halogenated polymers
Known methods include a solution method in which halogen is introduced into a carbon tetrachloride solution of EPM or EPDM, a gas phase method in which halogenation is carried out in the gas phase without using a medium, and an aqueous suspension method in which halogen is introduced by suspending it in water. This is obtained by The composition of the present invention is a composition using a halogen-containing ethylene-α-olefin copolymer and a halogen-containing ethylene-α-olefin-nonconjugated diene copolymer, but propylene is the most representative and important α-olefin. For this reason, as described above, α-olefinin is represented by propylene in this specification. Ethylidene norbornene (ENB) is a non-conjugated diene;
Examples include dicyclopentadiene (DCPD) and 1,4-hexadiene (1,4-HD). The composition of the present invention includes various carbon blacks, white fillers, process oils,
It contains processing aids, anti-aging agents, pigments, etc., and the content is determined empirically in consideration of the required physical properties and other characteristics. The present composition can be obtained using a kneader such as a Banbury, kneader, or roll kneader. In addition, vulcanization is accomplished using presses, vulcanizers, injection molding machines, and various continuous vulcanization devices to obtain various rubber products with excellent oil resistance and organic solvent resistance, such as hoses, packing, belts, linings, and gaskets. I can do things. Examples will be described below, but they do not limit the present invention. Examples 1 to 7, Comparative Examples 1 to 4 Ethylene-propylene-ethylidenenorbornene terpolymer EPDM (Mooney viscosity ML ₁ +4100
℃=45, Iodination=12, Ethylene content=55wt
%) based on chlorine content 15wt%, 25wt%
The chlorinated EPDM was kneaded with rolls according to the recipe shown in Table 1, and press vulcanization was performed at 160° C. for 60 minutes to obtain vulcanized rubber test pieces. Physical properties are
Measured in accordance with JISK6301. Table 2 shows the results of the tensile test and hardness test, and Table 3
The results of the oil resistance test are shown in Comparative Example 1, where the acid acceptor was composed of lead monoxide alone, and the vulcanization accelerators of Comparative Examples 2 to 4 were dithiocarbamates alone, thiurams alone, and thiazoles. When blended alone, sufficient physical properties cannot be obtained in any blend.

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Claims (1)

[Claims] 1. Halogen-containing ethylene-α-olefin copolymer or halogen-containing ethylene-α-olefin
In the non-conjugated diene copolymer, 1 to 50 parts by weight of calcium oxide per 100 parts by weight of these copolymers; 0.1 to 5.0 parts by weight of dithiocarbamates as vulcanization accelerators, 0.1 to 5.0 parts by weight of thiurams, 0.1 A sulfur-vulcanizable halogen-containing rubber composition, comprising ~5.0 parts by weight of thiazoles and/or guanidines; and 0.2-10.0 parts by weight of sulfur. 2. The halogen-containing rubber composition according to claim 1, further containing 1 to 50 parts by weight of magnesium and lead oxides. 3. The halogen-containing rubber composition according to claim 1 or 2, further containing 0.5 to 30 parts by weight of zinc stearate.