JPH01139605A - Vulcanizable blended rubber composition - Google Patents

Abstract

PURPOSE:To obtain the title composition having excellent heat and cold resistance for a long period, by blending an acrylic elastomer with ethylene-ethyl acrylate copolymer and covulcanizing the resultant blend with an organic peroxide in the presence of a polyfunctional monomer. CONSTITUTION:A rubber composition containing an acrylic elastomer (e.g., methyl acrylate, divinylbenzene, allyl glycidyl ether or ethylene), ethylene-ethyl acrylate copolymer, a polyfunctional monomer (e.g., triallyl cyanurate or m- phenylenebismaleimide) and an organic peroxide (e.g., benzoyl peroxide or dicumyl peroxide). The weight ratio of the acrylic elastomer to the ethylene- ethyl acrylate copolymer is preferably 30/70-95/5. The amounts of the components based on 100 pts.wt. blended rubber are preferably 0.5-6 pts.wt. organic peroxide and 1-10 pts.wt. polyfunctional monomer.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to vulcanizable blend rubber compositions.

More specifically, the present invention relates to a vulcanizable blend rubber composition that improves the heat resistance and cold resistance of acrylic elastomers.

[Prior Art] and [Problems to be Solved by the Invention] Acrylic elastomers are copolymer elastomers whose main component is acrylic ester, and generally have high heat resistance,
As a rubber with excellent oil resistance, it is used as a molding material for oil seals, O-rings, gaskets, hoses, etc.

However, due to recent improvements in the performance of equipment, oil, etc., and resource conservation, the reality is that materials with superior heat resistance and cold resistance have become more desirable than ever.

Therefore, as a result of various studies in search of a solution to this problem, the present inventors blended an acrylic elastomer with an ethylene-ethyl acrylate copolymer and applied organic peroxide in the presence of a polyfunctional monomer. It has been found that such problems can be effectively solved by co-curing with a material.

[Means for solving problems]

Accordingly, the present invention relates to a vulcanizable blend rubber composition, which comprises an acrylic elastomer, ethylene-ethyl acrylate-1, a copolymer, a polyfunctional monomer, and an organic peroxide. Contains.

As the acrylic elastomer which is one component of the blended rubber, the following is used.

Approximately 50 to 1 at least one acrylate selected from the group consisting of (a) an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms and (b) an alkoxyalkyl acrylate having an alkoxyalkyl group having 2 to 8 carbon atoms
00% by weight For example, methyl acrylate, ethyl acrylate, n
- or iso-propyl acrylate, n- or iso-butyl acrylate, rhoamyl acrylate, n-
Alkyl acrylates such as hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, 2-cyanoethyl acrylate, preferably ethyl acrylate or n-butyl acrylate, or methoxymethyl acrylate, ethoxymethyl acrylate, 2-methoxyethyl acrylate , 2-ethoxyethyl acrylate, 2-butoxyethyl acrylate, and other alkoxyalkyl acrylates, preferably 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate (c) about 5 to 0% by weight of a diene monomer, for example, divinylbenzene , piperylene, isoprene,
Pentagene, vinylcyclohexene, chloroprene,
Butadiene, methylbutadiene.

Cyclopentadiene, methylpentadiene, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, ethylidene norbornene,
Vinylidene norbornene, allyl (meth)acrylate, 2-butenyl (meth)acrylate, ethylidenenorbornene (meth)acrylate, dicyclopentadiene (meth)acrylate (d) Vinyl monomer containing crosslinkable group, about 5 to 0 weight 2 e.g. , epoxy group-containing vinyl monomers such as allyl glycidyl ether, glycidyl (meth)acrylate, vinyl glycidyl ether, acrylic acid,
Carboxyl group-containing vinyl monomers such as methacrylic acid, itaconic acid, maleic acid, maleic anhydride, hydroxyl group-containing vinyl monomers such as hydroxyalkyl (meth)acrylate, hydroxyalkoxyacrylate, N-methylolacrylamide, 2-thalol Reactive halogen-containing vinyl monomers such as ethyl vinyl ether, monochloroacetic acid, chloromethylstyrene, etc. (e) At least one monomer copolymerizable with these polymerizable monomers, about 40 to 0% by weight2, for example, ethylene , propylene, vinyl chloride, vinylidene chloride, acrylonitrile, styrene, vinyl acetate, ethyl vinyl ether, butyl vinyl ether, alkyl methacrylate, alkoxyalkyl methacrylate The above components can be copolymerized by any polymerization method, but preferably by A turbidity polymerization method or an emulsion polymerization method is used.

The ethylene-ethyl acrylate copolymer which is the other component of the blended rubber generally has an ethyl acrylate content of about 5 to 60% by weight. Moreover, this copolymer is produced by a pressure polymerization method.

The acrylic elastomer and ethylene-ethyl acrylate copolymer that form the blended rubber generally have a
/70 to 9515 by weight. If the acrylic elastomer is used in a proportion greater than this, the desired modification effect will not be obtained, while if the proportion is less than this, it will no longer exhibit a rubber-like appearance.

Both of these rubber components are organic peroxides such as benzoyl peroxide, 2,4-dichloro-benzoyl peroxide, 1,1-di(tert-butylperoxy)-3,3
, 5-trimethylcyclohexane, n-butyl-4゜4
-Bis(tert-butylperoxy)valerate, dicumyl peroxide, ditert-butylperoxy-diisopropylbenzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5- dimethyl-2,5-
Co-vulcanization is performed using di(tert-butylperoxy)hexyne-3 or the like.

These organic peroxides are used in an amount of about 0.1 to IO parts by weight, preferably about 0.5 to 5 parts by weight, per 100 parts by weight of the blended rubber. If the proportion of organic peroxide used is lower than this, the vulcanizate will not have sufficient tensile strength due to the inorganic content, while if the proportion of organic peroxide is higher than this, the elongation of the vulcanizate will decrease. becomes larger.

When co-vulcanizing the blended rubber with an organic peroxide, a polyfunctional monomer is allowed to coexist. Examples of polyfunctional monomers include triallyl cyanurate, triallyl isocyanurate, triallyl trimellitate, trimethylolpropane trimethacrylate, polyethylene glycol di(meth)acrylate, -phenylene bismaleimide, and the like.
Approximately 0.1 to 20 parts by weight per 100 parts by weight of blended rubber,
Preferably, it is used in a proportion of about 1 to 10 parts by weight. If the proportion used is less than this, the 100% modulus and tensile strength among normal physical properties will be significantly reduced, while if the polyfunctional monomer is used in a larger amount than this, the elongation of the vulcanizate will be greatly reduced.

The vulcanizable blend rubber composition is prepared by adding the above-mentioned components together with other known compounding agents such as reinforcing agents, fillers, stabilizers, plasticizers, lubricants, etc. using a roll mixing method, Banbury mixing method, etc. This is done by mixing in the manner described. The vulcanization thereof is - generally about 150-190°C, about 5-2
Press vulcanization for 0 minutes and about 150-180℃, about 2~
This is done by secondary vulcanization for 15 hours.

〔Effect of the invention〕

The vulcanizable blend rubber composition according to the present invention has ethylene-
By using a blend of ethyl acrylate copolymer, it has superior long-term heat resistance compared to the case where acrylic elastomer is used alone. This is supported by the fact that the range of changes in the rate of change is small, and it is also excellent in terms of cold resistance.

〔Example〕

Next, the present invention will be explained with reference to examples.

Reference Example: 150 parts of water (by weight) was placed in a separable flask equipped with a thermometer, stirrer, nitrogen inlet tube, and pressure reducing device.

(same below), 0.1 part of sodium sulfate, 5.5 parts of emulsifier (1,5:2.0:2.0 mixture of Kao product Emal 10, Emulgen 147, and Lebenol wZ), and the monomer mixture shown in Table 1 below. After charging a total of 100 parts of the mixture, the oxygen in the system was sufficiently removed by repeating deaeration and nitrogen substitution.

0.06 part of sodium hydrosulfide, 0.06 part of sodium formaldehyde sulfoxylate, and 0.03 part of tert-butyl hydroperoxide were added to initiate a polymerization reaction at room temperature. Polymerization conversion rate is 95-9g
After continuing the reaction for 6 hours so as to keep the amount within the range of 1.5%, the reaction mixture was salted out, thoroughly washed with water, and dried to obtain acrylic elastomers A-D.

Table 1 Ethyl acrylate 95.097.736,
037.7n-butyl acrylate
30,030.0 Methoxyethyl acrylate 30,0
30.0 Acrylonitrile 2.0 2.
0 2.0 2.0 Allyl methacrylate
0.3 0.3 glycidyl methacrylate
2.0 vinyl chloroacetate 3.0 Example 1 80 parts of the above acrylic elastomer A, ethylene-ethyl acrylate copolymer (Nippon Unicar product EEA M
B-870, ethyl acrylate content 41 weight 120
part, stearic acid 1 part, HAF carbon black 45 parts, anti-aging agent (Schroyal product Noguard 445,
2 parts of substituted diphenylamine), 3 parts of m-phenylenebismaleimide and 1 part of ditert-butylperoxy-diisopropylbenzene were mixed on an open roll under cooling,
The prepared vulcanizable blend rubber composition was heated at 180°C for 10
Press vulcanization for 1 minute and secondary vulcanization in a gear oven at 150° C. for 15 hours were carried out.

Regarding the vulcanizate, its normal physical properties were measured according to JIS K-6301, and a long-term heat aging test was conducted at 175°C to measure the change in hardness, rate of change in tensile strength, and rate of change in elongation. High-temperature oil resistance (volume change rate after 70 hours of immersion in ASTM Na3 oil at 150°C), compression set, and embrittlement point were also measured.

Example 2 In Example 1, instead of acrylic elastomer A,
The same amount of acrylic elastomer 8 was used.

Example 3 In Example 1, instead of acrylic elastomer A,
The same amount of acrylic elastomer D was used and also HAF
The amount of carbon black added was changed to 50 parts.

Example 4 In Example 1, acrylic elastomer A was replaced with 6
0 parts of acrylic elastomer 〇 was used, and the amount of ethylene-ethyl acrylate copolymer was changed to 40 parts.

Example 5 In Example 4, instead of acrylic elastomer C,
The same amount of acrylic elastomer 〇 was used.

Comparative Example 1 100 parts of acrylic elastomer A, 1 part of stearic acid, 50 parts of HAF carbon black, 2 parts of anti-aging agent (Nougat 4/15), 2.5 parts of sodium stearate.

The same operation as in Example 1 was carried out using 0.5 part of potassium stearate and 0.3 part of sulfur.

Comparative Example 2 In Example 2, only acrylic elastomer B was used at 100% without using the ethylene-ethyl acrylate copolymer.
parts, and the amount of HAF carbon black added was changed to 50 parts.

Comparative Example 3 100 parts of acrylic elastomer C, 1 part of stearic acid,
The same procedure as in Example 1 was carried out using 55 parts of HAF carbon black, 2 parts of anti-aging agent (Nogard 445) and 2 parts of zinc dimethyldithiocarbamate.

Comparative Example 4 In Example 5, only the acrylic elastomer ○ was used at 100% without using the ethylene-ethyl acrylate copolymer.
parts, and the amount of HAF carbon black added was changed to 55 parts.

The measurement results for each of the above examples and comparative examples are as follows.

It is shown in Table 2 below.

(Margin below)

Claims (1)

[Claims] 1. A vulcanizable blend rubber composition comprising an acrylic elastomer, an ethylene-ethyl acrylate copolymer, a polyfunctional monomer, and an organic peroxide. 2. The vulcanizable blend rubber composition according to claim 1, wherein the acrylic elastomer and the ethylene-ethyl acrylate copolymer are used in a weight ratio of about 30/70 to 95/5.