JPH03109449A - Rubber composition with improved low-temperaure resistance and heat resistance - Google Patents

Abstract

PURPOSE:To provide the title composition resistant to ozone and oil, improved in both low temperature and heat resistance, thus suitable for O-rings to be used in the bearings of rotary machines, consisting mainly of a nitrile group- contg. highly saturated copolymer rubber of specific constitution. CONSTITUTION:The objective composition can be obtained by incorporating a variety of ingredients (e.g. sulfur) in a nitrile group-contg. highly saturated copolymer rubber (e.g. butadiene-butyl acrylate-acrylonitrile copolymer rubber) made up of (A) 5-40wt.% of unsaturated nitrile monomer unit, (B)41-80wt.% of fluorine-free unsaturated carboxylic ester monomer unit, (C) <=20wt.% of conjugated diene monomer unit, and (n) the rest of hydrogenated conjugated diene monomer unit with A+B=46-90wt.% and C+D=10-54wt.%.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides a rubber composition with improved cold resistance and heat resistance, which contains a nitrile group-containing copolymer rubber having a specific composition and a low amount of unsaturated bonds as a rubber component. It is something that takes place in between.

(Prior art) In order to prevent automobile exhaust gas, rubber parts around the engine are required to have a high degree of heat resistance. Against this background, nitrile group-containing hydrocarbon rubber (for example, acrylonitrile-butadiene rubber) has been developed. Highly saturated polymeric rubber containing nitrile groups, in which part or all of the carbon-carbon double bond-containing monomer units in polymeric rubber (hereinafter sometimes abbreviated as NBR) are hydrogenated, has been developed and used.

Although this rubber has extremely superior ozone resistance and heat resistance compared to conventional NBH, its cold resistance may be inferior to NBR depending on the content of nitrile groups and the degree of unsaturation.

Due to recent advances in technology, the temperature of the atmosphere in which various rubber parts are used has widened from lower to higher temperatures, and highly saturated polymer rubber compositions containing nitrile groups with improved cold resistance have been developed. Development was strongly requested. In order to improve this cold resistance, the present inventors first discovered that a nitrile group-containing highly saturated copolymer rubber containing an unsaturated carboxylic acid ester monomer as a constituent unit is effective.

(Japanese Unexamined Patent Publication No. 63-95242) It has been desired to further improve both the cold resistance and heat resistance of L/oak.

(a!M to be solved by the invention) As a result of intensive studies by the present inventors to improve the cold resistance and heat resistance of highly saturated copolymer rubber containing nitrile groups, it was found that the monomer composition of the rubber is It has been discovered that when the conditions are met, cold resistance and heat resistance are further improved, and a composition with an excellent balance of cold resistance, heat resistance, and oil resistance can be obtained, and based on this knowledge, the present invention has been completed. It was.

(Means for Solving the Problems) Thus, according to the present invention, the content of each bonded monomer unit in the copolymer chain is (1) 5 to 40% by weight of unsaturated nitrile monomer units (2
) 41 to 80% by weight of unsaturated carboxylic acid ester monomer units that do not contain fluorine (3) 20% by weight or less of conjugated diene monomer units (4) the remainder of hydrogenated conjugated diene monomer units, and the total of monomer unit (1) and monomer unit (2) is 46 to 90% by weight, and the total of monomer unit (3) and monomer unit (4) is 1
A rubber composition with improved cold resistance and heat resistance is provided, which is comprised of a highly saturated copolymer rubber containing nitrile groups of 0 to 54% by weight and a compound.

By using the rubber composition of the present invention, T
Rl0 (indicates the temperature at which the length of the stretched test piece shrinks (recovers) by 10% by continuously increasing the temperature after freezing the stretched test piece) is -26°C or less (40 parts by weight of SRF carbon black/ It becomes possible to produce a vulcanizate of 100 parts by weight of rubber (without using a degradable agent).

The content of the unsaturated nitrile monomer unit (1) in the nitrile group-containing highly saturated copolymer rubber used in the present invention is preferably 5 to 40% by weight in view of the requirements for oil resistance and cold resistance. If the weight percentage is below the groove, the oil resistance will be poor, and if it exceeds 40 weight percent, the effect of improving cold resistance will be insufficient. Also cold resistance,
The content of the fluorine-free unsaturated carboxylic acid ester monomer unit (2) introduced to improve heat resistance is 41
~80% by weight. 41% by weight ungrooved material also has the effect of improving cold resistance, but the effect of improving heat resistance is insufficient, and 80% by weight
If it exceeds % by weight, the effect of improving cold resistance will be small. Preferably it is 45 to 60 moss by weight.

From the point of view of heat resistance, the conjugated diene monomer unit (
The content of 3) is 20% by weight or less, preferably 15% by weight.
It is as follows. The remainder of the content of each monomer unit mentioned above is the content of the hydrogenated conjugated diene monomer unit (4).

In addition to the above requirements, in order to balance oil resistance, heat resistance, and cold resistance, the total amount of monomer units (1) and monomer units (2) in the rubber must be 46 to 90% by weight. can be,
Furthermore, from the point of view of the balance between heat resistance and cold resistance, monomer units (
The total amount of 3) and monomer unit (4) must be 10 to 54%.

The nitrile group-containing highly saturated copolymer rubber of the present invention is a copolymer rubber obtained by copolymerizing an unsaturated nitrile monomer, a fluorine-free unsaturated carboxylic acid ester monomer, and a conjugated diene monomer. This is a rubber in which the conjugated diene monomer units inside are hydrogenated using a conventional method.

The monomers used to produce the copolymer rubber of the present invention are illustrated below.

Examples of the unsaturated nitrile monomer include acrylethrile, methacrylaterile, α-chloroacrylonitrile, and the like.

Examples of unsaturated carboxylic acid ester monomers that do not contain fluorine include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-pentyl acrylate, isononyl acrylate, and n-hexyl. Acrylates and methacrylates having alkyl groups with about 1 to 18 carbon atoms, such as acrylate, 2-methyl-pentyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, n-dodecyl acrylate, methyl methacrylate, and ethyl methacrylate; methoxymethyl Acrylates having alkoxyalkyl groups having about 2 to 12 carbon atoms in total, such as acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, butoxyethyl acrylate, ethoxypropyl acrylate, methoxyethoxyacrylate, and ethoxybutoxyefrylate; α- and β-cyanoethyl acrylate; 2-1 carbon atoms such as α, β and γ-cyanopropyl acrylate, cyanobutyl acrylate, cyanohexyl acrylate, cyanooctyl acrylate, etc.
Acrylate having about 2 cyanoalkyl groups; 2-
Acrylates with hydroxyalkyl groups such as hydroxyethyl acrylate and hydroxypropyl acrylate; monoethyl maleate, dimethyl maleate, dimethyl fumarate, diethyl fumarate, di-n- fumarate
Examples include unsaturated dicarboxylic acid mono- and dialkyl esters such as butyl, di-2-ethylhexyl fumarate, dimethyl itaconate, diethyl itaconate, di-n-butyl-itaconate, and di-2-ethylhexyl itaconate.

Conjugated diene monomers include 1,3-butadiene, 2.
Examples include 3-dimethylbutadiene, isoprene, 1,3-pentadiene, and the like. In addition to these monomers, vinyl monomers such as styrene and vinylpyridine, vinyl norbornene, dicyclopentadiene, 1,4 - You may substitute with a monomer copolymerizable with each of the above monomers, such as a non-conjugated diene monomer such as hexadiene.

The nitrile group-containing highly saturated copolymer rubber used in the present invention is a rubber obtained by copolymerizing the above-mentioned monomers by a conventional polymerization method, and a rubber obtained by hydrogenating the conjugated diene monomer units of this rubber.

Specifically, butadiene-butyl acrylate-acrylonitrile copolymer rubber, butadiene-isononyl acrylate-acrylonitrile copolymer rubber, butadiene-di-n-butyl itaconate-acrylonitrile copolymer rubber, and the butadiene units of these rubbers are hydrogenated. Examples include:

The rubber composition of the present invention is made into a compounded rubber composition by mixing a nitrile group-containing highly saturated copolymer rubber and various compounding agents commonly used in the rubber industry using a conventional mixer. The type and amount of compounding agents used are determined according to the intended use (application) of the rubber composition, and are not particularly limited in the present invention.

Compounding agents include sulfur, sulfur-donating compounds such as tetramethylthiuram disulfide, zinc white, stearic acid, and various vulcanization accelerators (guanidine, thiazole, thiuram, dithioate salts, etc.). Sulfur vulcanization system; dicumyl peroxide, 2,5-dimethyl-2,5
- Organic peroxide vulcanization system using di(t-butylperoxy)hexyne-3 and the like together with a crosslinking aid such as triallyl cyanurate and trimethylolpropane trimethacrylate; SRF, HAF, FEA, etc. Various grades of carbon black, reinforcing agents such as silica, talc, calcium carbonate, fillers, plasticizers, process oils, processing aids, anti-aging agents, etc. are commonly used.

(Effect of the invention) By using the rubber composition of the invention, highly saturated NB
TR10, which cannot be obtained with rubber compositions using R, is -26
℃ or less (SRF carbon black 40 parts by weight/rubber 10 parts
It is possible to produce vulcanized rubber products using 0 parts by weight (using no plasticizer).

The rubber composition of the present invention has ozone resistance and oil resistance, which are characteristics of nitrile group-containing highly saturated copolymer rubber, and has particularly improved cold resistance and heat resistance.
It is effective when used in the production of rubber products that come into contact with gas etc. and require heat resistance and oil resistance, especially rubber products that require cold resistance.

Therefore, the rubber products targeted by the present invention include various sealing rubber products such as O-rings, backings, and gaskets used in bearings of rotating equipment; various belts such as conveyor belts, ■-belts, and tamming belts; valves; Sheet material: Packer well rad seal used in oil wells, BOP ([31gwoutPreventar)
, Bladders, etc.; Various cushion materials, anti-vibration phase, etc.; Bearing seals for ships and automobiles, such as crankshaft seals, bass ring seals, accelerator rotary seals, stern tube seals; Various diaphragms; Automobile fuel hoses, marine hoses, risers. Examples include hoses such as flow lines; rubber products for a wide range of uses such as in the energy field such as geothermal power generation.

(Example) The present invention will be described in more detail with reference to Examples below. Note that parts and percentages in Examples, Comparative Examples, and Reference Side are based on weight unless otherwise specified.

Example 1 Butadiene-acrylonitrile copolymer rubber, butadiene-acrylonitrile-diethyl itaconate ternary copolymer rubber, and butadiene-acrylonitrile-di-n-butyl itaconate ternary copolymer rubber prepared by conventional emulsion polymerization were separately treated with methyl Dissolved in isobutyl ketone, P, d
The butadiene unit portion in each rubber was partially hydrogenated using a silica catalyst in a pressure vessel to obtain a highly saturated copolymer rubber.

Table 1 shows the monomer unit content of these rubbers.

Each of the obtained highly saturated copolymer rubbers and the compounding agents listed in the compounding recipe in Table 2 were mixed on a cooling roll to obtain a rubber composition, and these were heated under pressure at 170° C. for 15 minutes. A vulcanizate was prepared.

The TR test of the vulcanizate was conducted according to ASTM D-1329. Other vulcanization physical properties were measured according to JIS-6301. The results are also listed in Table 1.

Table (Combination prescription) Note Xi) Montecatini (Italy) product Per
oximon F2O (α, α′-bis-1-butyl peroxide of n+*p-diisopropylbenzene) As is clear from Table 1, even copolymer rubber containing unsaturated carboxylic acid ester units can be used according to the present invention. If the requirements are not met (experiment numbers 7, 8°9, 10.11), the cold resistance (TR10) is not improved and the heat resistance is not improved either.

Example 2 Using the highly saturated copolymer rubber shown in Table 3 obtained in the same manner as in Example 1, a rubber composition was prepared according to the formulation shown in Table 2, and heated under pressure at 170°C for 15 minutes. Obtained sulfur. The properties of the vulcanizate are shown in Table 3.

Example 3 A rubber composition was prepared by adding and mixing the compounding agents listed in Table 4 to each of the hydrogenated copolymer rubbers of the invention examples of Examples 1 to 2, and press-vulcanized at 160°C for 20 hours to obtain a rubber composition. vulcanizate T
R10 was measured. The results reproduced those shown in Examples 1-2.

Table 4 (Combination prescription) Patent” person, Hakumoto Daon Co., Ltd.

Claims (1)

[Claims] 1. The content of each monomer unit bonded in the copolymer chain is (1)
5-40% by weight of unsaturated nitrile monomer units (2) 41-80% by weight of unsaturated carboxylic acid ester monomer units that do not contain fluorine (3) 20% by weight or less of conjugated diene monomer units ( 4) The remainder of the hydrogenated conjugated diene monomer units, and the total of monomer units (1) and monomer units (2) is 46 to 90% by weight.
and the total of monomer units (3) and monomer units (4) is 10
A rubber composition with improved cold resistance and heat resistance, comprising a highly saturated copolymer rubber containing nitrile groups of ~54% by weight and a compound.