JPS60155249A - Ethylene/propylene rubber composition - Google Patents

Abstract

PURPOSE:To enable vulcanization in the presence of air to be carried out, by using a rubber compsn. contg. a specified process oil in the vulcanization of an EPR rubber compsn. using an org. peroxide as a vulcanizing agent. CONSTITUTION:A rubbery resin compsn. which can be vulcanized in the presence of air is obtd. by blending not more than 50pts.wt. process oil having an aniline point of 50 deg.C or above and 1-10pts.wt. org. peroxide such as diacyl peroxide with 100pts.wt. ethylene/propylene rubber (which may contain the third component such as ethylidenenorbornene). When a process oil having an aniline point below 50 deg.C is used, the process oil is blended in a quantity satisfying the formula [wherein Y is the upper limit of the quantity of process oil having an aniline point below 50 deg.C to be blended, and X is aniline point ( deg.C) of process oil].

Description

[Detailed description of the invention] Y = X / 1.25 + 10 Y Upper limit of the amount of process oil with an aniline point of 50°C or less This invention relates to an ethylene-propylene rubber (hereinafter abbreviated as EP rubber) composition that can be vulcanized in air.

Vulcanized rubber products that use organic peroxides as rubber vulcanizing agents have better heat aging resistance, less compression set, less staining, and produce clearer vulcanized rubber than sulfur vulcanizates. It has characteristics such as being able to be used in electrical insulation materials, automobile parts, rubber plugs, etc. However, all of the vulcanized rubber products using these organic peroxides use air as the vulcanization method.
Press vulcanization without air or vulcanization in other heat carriers (for example molten salt) with air replacement has been applied.

The biggest drawback of using an organic peroxide as a vulcanizing agent is that vulcanization methods involving air, such as hot air vulcanization or steam can vulcanization, cannot be applied. this is,
Cutting of rubber molecules caused by polymer radicals generated by organic peroxides combining with oxygen in hot air.
Alternatively, it may be due to inactivation, and conventional techniques cause significant stickiness on the surface of the vulcanizate.

The present inventors have arrived at the present invention as a result of extensive research into a method of vulcanizing an EP rubber composition in the presence of air by blending an organic peroxide as a vulcanizing agent.

The present inventors have determined that when an organic peroxide is used as a vulcanizing agent and an EP rubber composition is vulcanized in heated air, the properties and amount of process oil to be blended into a BP rubber composition. was found to have a significant influence.

In other words, process oil with an aniline point of 50°C or higher is B.
P rubber 100! 50 parts by weight or less, further,
It has been discovered that organic peroxide vulcanization can be carried out in heated air by limiting the blending of process oils with an aniline point of 50° C. or lower to less than Y parts by weight as shown by the following formula.

Y = X / 1.25 + 10 Y 2 points Upper limit of the amount of process oil blended below 50 ° C: Aniline point ('C) of process oil The present invention
For 100 parts by weight of natural rubber containing PLL or BP rubber, or a mixture with other synthetic rubber, process oil is blended in parts by weight within the above limits, and one or more organic peroxides are blended as necessary. It is made by blending co-crosslinking agents, reinforcing agents, synthetic plasticizers, calcium oxide, zinc oxide, stearic acid, fillers, anti-aging agents, etc., which are known in the rubber industry, and can be vulcanized in heated air. This provides an EP rubber composition.

The process oil in the present invention is a petroleum-based process oil, preferably an oil having an aniline point of 50° C. or higher.

The amount of process oil is limited because if the amount exceeds the limited weight part, the strength of the vulcanized rubber decreases, the surface of the vulcanized rubber becomes soft and sticky, and it cannot be used practically.

The organic peroxide used in the present invention is diacyl peroxide, peroxy ester, dialkyl peroxide, or perketal type.
For example, 1-
Addition of 10 parts by weight is preferred.

EPPLL in the present invention is an ethylene-propylene copolymer rubber, ethylene and propylene, and a monomer having a non-conjugated double bond (for example, ethylidenenorbornene, dicyclopentadiene, 1,4e hexadiene, methylnorbornene, 4,7, Refers to copolymer rubber containing one or more types of 8.9 tetrahydroindene, etc.).

Prior to molding the composition of the present invention, processing aids known in the rubber processing industry, such as zinc stearate, diethylene glycol, polyethylene, liquid polyisoprene, etc., may be added to further improve processability. As well as conventional sulfur vulcanization formulations and peroxide formulations for press vulcanization, antioxidants, such as 2,6. Heat resistance can also be improved by adding ditertiary butyl 4-methylphenol, trisnonylphenyl phosphate, 2-mercaptobenzothiazole, ketone amine condensate, etc.

The composition of the present invention usually contains additives to improve crosslinking efficiency during organic peroxide vulcanization, such as dibenzoyl P.
- Quinone dioxime, quinone dioxime, dipentamethylene thiuram tetrasulfide, sulfur, ethylene dimethacrylate, m-phenylene bismaleide, triallylisocyanurate, trimethylolpropane trimethacrylate, etc. may be added.

The present invention will be specifically explained below using Examples.

However, this example does not limit the present invention.

Example 1 Table 1 shows examples of blending of various fillers, process oils, etc. to 100 parts by weight of ethylene/propylene rubber. Moreover, in order to clarify the characteristics of the present invention, many examples other than the present invention are also shown.

An oven roll was used for mixing. The resulting mixture is 4
Using a 5 fl female screw extruder, the thickness is 1 g, the width is 2
Formed into a tape with 0 fins and heated at 140°C and 180°C.
The sample was placed in a hot air normal pressure vulcanizer and vulcanized in hot air for a predetermined period of time.

Table 2 shows the results of a tensile test performed on the tape after vulcanization according to JIS-6801 method and the observation results of the surface condition of the obtained tape.

These results show that the ethylene-propylene rubber composition of the present invention can be vulcanized in heated air, which was previously considered impossible. Furthermore, it can be seen that a good vulcanizate can be obtained even if conventionally known co-crosslinking agents, anti-aging processing aids, etc. are added to the composition of the present invention. - Example 2 Table 3 shows blending examples of fillers, organic peroxides, crosslinking aids, etc., with respect to 100 parts by weight of ethylene/propylene rubber, along with comparative examples.

The crossing method and molding method were the same as in Example-1.

The formed unvulcanized tape was placed in a vulcanizing can, and the air pressure was maintained at 5.9 kqf/cd, and the tape was vulcanized in pressurized hot air at 160° C. for 60 minutes.

The tape after the vulcanization operation was subjected to a tensile test and surface state observation in the same manner as in Example 1, and the results are shown in Table 4.

The results show that the ethylene-propylene rubber composition of the present invention can provide a good vulcanized rubber even in pressurized hot air.

On the other hand, the surface of the comparative example was extremely sticky, and the ethylene/propylene rubber components may have decomposed due to the hot air.
Or, the organic peroxide is not effectively consumed for crosslinking.
This was in accordance with conventional knowledge.

Table 1 Example 1 Formulation example (numbers in the table are parts by weight) 1) Ethylene propylene rubber: Ethylene-propylene-dicyclopentadiene terpolymer manufactured by Sumitomo Chemical. Mooney viscosity 60ML1+4 (100℃) 2) Calmos: Shiraishi Kogyo, surface treated calcium carbonate 8
) White Glossy CjC: tt 4) Nibusyl VN9: Hydrous silicic acid manufactured by Nippon Silkani Industry ■ 5) Perhexa 8M Nippon Oil & Fats ■ 1,1-bistercial butylperoxy-8,8,6-)limethylcyclohexane No. Table 1 (Continued) 6) Kyodo Sekiyu 11J aromatic process oil Aniline point 16.8°C) Naphthene-based manufactured by Sun Oil ■ Aniline point 80°C 8) Paraffin-based manufactured by Idemitsu Oil Aniline point 125°C 9) ■ Kuraray Liquid polyisoprene manufactured by Sumitomo Chemical Co., Ltd. Table 1 (Continued) 10) Ethylene-propylene-ethylidene-norbornene terpolymer manufactured by Sumitomo Chemical Co., Ltd. Mooney viscosity 90 M
L1+4 (100'c) 11) Ethylene-propylene copolymer rubber Mooney viscosity 60MLl+4 (100°C) Table 1 (continued) t*) 2,5-dimethyl-2,5 di(t-butylperoxy)hexane (Japan) Ill) Manufactured by Sumitomo Chemical Co., Ltd. Antioxidant 2-Mercaptobenzimidazole 14) Manufactured by Sumitomo Chemical Co., Ltd. Ketone-Tamine condensate Table 2 Result: Condition of the surface of the vulcanizate: Not yet.

B: Adhesive.

Table 2 (continued) Table 2 (continued) Table 1112 (continued) Table 8 Example-2 formulation Table 4 Physical properties of vulcanizate: B: The surface of the vulcanizate is not sticky. It has a sticky surface.

Claims (2)

[Claims] (1) Ethylene/propylene rubber or ethylene/propylene rubber
To 100 parts by weight of a mixture containing propylene rubber and other rubber species, in the presence of at least one organic peroxide, process oil with an aniline point of 50°C or higher is added at 0 to 50% by weight.
An unvulcanized ethylene/propylene rubber composition characterized in that it can be vulcanized in heated air, and a vulcanized rubber composition obtained by vulcanizing the composition in hot air. (2) In the presence of at least one organic peroxide, the blending and amount of process oil is reduced to 100 parts by weight of ethylene/propylene rubber or a mixture with other rubber types including ethylene/propylene rubber. An unvulcanized ethylene/propylene rubber composition containing not more than Y parts by weight represented by the formula and capable of being vulcanized in heated air, and a vulcanized composition obtained by vulcanizing the composition in hot air. Rubber composition.