JPH11302454A - Composition for vibration insulating rubber and vibration insulating rubber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition for the preparation of a vibration insulating rubber exhibiting durability as well as vibrationproofing properties well-balanced with soundproofing properties. SOLUTION: The titled vibration insulating rubber composition comprises a rubber component comprising (a) 5-90 wt.% of an aromatic vinyl monomer- butadiene copolymer rubber having an average bonded aromatic vinyl monomer content (such as styrene or the like) of 10-40 wt.% and a 1,2-linkage content in the whole butadiene units of 50 wt.% or more, the bonded aromatic vinyl monomer content increasing or decreasing along the polymer chain from one end to the other, (b) 5-90 wt.% of a polybutadiene rubber and (c) 5-90 wt.% of a diene rubber other than the components (a) and (b) above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-vibration rubber composition which can be used for producing an anti-vibration rubber for an automobile engine mount and the like, and an anti-vibration rubber using the same.
The present invention relates to an anti-vibration rubber composition and an anti-vibration rubber which are excellent in anti-vibration property and sound-proof property and excellent in fatigue resistance property.

[0002]

2. Description of the Related Art Anti-vibration rubber used for automobile engine mounts and the like is required to have anti-vibration and sound-proof properties. Anti-vibration means that the frequency of shakes etc. due to engine vibration is 5
The performance of absorbing low frequency vibration of 30 Hz, and the soundproofing property is a performance of reducing a muffled sound having a frequency of about 100 to 200 Hz generated by engine sound, contact between a tire and a road surface, or unevenness of a road. However, in general, the anti-vibration properties and the anti-sound properties are contradictory properties. Therefore, it has been extremely difficult to obtain anti-vibration rubber satisfying the above two performances by using a conventional rubber as a rubber component.

[0003] For the above reasons, liquid seal mounts have recently been used as engine mounts. The liquid ring mount is provided with a hollow chamber divided by a membrane in a rubber block, and a liquid such as ethylene glycol is sealed in the hollow chamber. In the liquid ring mount, a rubber block is formed by a rubber material having a function of damping vibration by a liquid moving between hollow chambers through a communication passage (orifice) provided in a membrane and a rubber material having characteristics similar to a spring. Function to enhance soundproofing. However, the liquid ring mount has a complicated structure, requires many man-hours for manufacturing, and is costly. Therefore, there is a demand for a vibration-proof rubber made of a rubber material itself having vibration-proof and sound-proof properties.

In order to meet such a demand, a method of using a synthetic rubber having a molecule modified as a rubber component (Japanese Patent Publication No.
JP-A-62808), a method using a tapered styrene-butadiene copolymer rubber in which the amount of bound styrene increases or decreases from one end to the other end along the polymer molecular chain (Japanese Patent Publication No. 7-88439), and the like. Has been proposed. However, in these methods, it is not possible to provide the vibration-proof rubber and the sound-proof property to a satisfactory level, and a vibration-proof rubber having a lower dynamic magnification is demanded. It was extremely difficult to maintain and reduce the dynamic magnification.

Japanese Patent Application Laid-Open No. 8-73658 discloses that a natural rubber / polybutadiene rubber blend is used as a rubber component.
A method of improving soundproofing (reducing dynamic magnification) by adding a specific carbon black thereto has been proposed, but this method does not provide a sufficient balance between heat resistance and vibrationproofing and soundproofing. Still, further improvements are needed.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a vibration-proof rubber having durability and a balance between vibration-proof and sound-proof. An object of the present invention is to provide a rubber composition that can be manufactured. The present inventors have assiduously studied to achieve the above object, and as a result, the amount of the bound aromatic vinyl monomer increases or decreases from one end to the other along the polymer molecular chain. By using rubber-butadiene copolymer rubber, polybutadiene rubber, and other diene rubbers as rubber components, the obtained vibration-proof rubber is found to have remarkably improved strength and durability, and also have a reduced dynamic magnification. The present invention has been completed based on this finding.

[0007]

According to the present invention, there is provided (a) a copolymer rubber of an aromatic vinyl monomer and butadiene, wherein the average amount of the bonded aromatic vinyl monomer is 10 to 4;
0% by weight, the content of 1,2 bonds in all butadiene units is 5
0% by weight or more, from 5 to 95% by weight of an aromatic vinyl monomer-butadiene copolymer rubber in which the amount of bound aromatic vinyl monomer increases or decreases from one end to the other along the polymer molecular chain; (B) 5 to 90% by weight of a polybutadiene rubber, and (c) 5 to 5% of a diene rubber other than the above (a) and (b).
Disclosed are a vibration-insulating rubber composition comprising a rubber component comprising 90% by weight and a compounding agent, and a vibration-proof rubber using the same.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in more detail with reference to embodiments. The composition for vibration damping rubber of the present invention comprises, as rubber components, a copolymer rubber of component (a) and component (b)
And a rubber component composed of a polybutadiene rubber and a diene rubber other than the components (a) and (b) of the component (c). Component (a) used in the present invention
Has an average amount of bound aromatic vinyl monomer of 10
Fragrance in which the content of 1,2-bonds in all butadiene units is 50% by weight or more, and the amount of bound aromatic vinyl monomer increases or decreases from one end to the other along the polymer molecular chain A group vinyl monomer-butadiene copolymer rubber.

The aromatic vinyl monomer used for polymerizing the copolymer rubber of the component (a) of the present invention is a vinyl monomer having an aromatic ring structure, and a benzene ring or a pyridine ring. Is preferred, for example, styrene, α-methylstyrene, 2-methylstyrene, 3-methyl-styrene, 4-methylstyrene, 2,4
-Amino group-free aromatic vinyl monomers such as diisopropylstyrene, 2,4-dimethylstyrene, 4-t-butylstyrene, 5-t-butyl-2-methylstyrene, monochlorostyrene, dichlorostyrene and monofluorostyrene Aminostyrene, 2-N, N-dimethylaminostyrene, 4-N, N-dimethylaminostyrene,
2-N, N-bis (trimethylsilyl) aminostyrene, 2-vinyl (N, N-diisopropylbenzamide), 4-vinyl (N, N-diisopropylbenzamide), N, N-dimethylaminoethylstyrene, N, N
-Amino group-containing aromatic vinyl monomers such as -diethylaminoethylstyrene, 2-vinylpyridine and 2-vinyl-4-amino-vinylpyridine. Among these, an amino group-free aromatic vinyl monomer is preferable,
Particularly, styrene is preferred.

[0010] The copolymer rubber of the component (a) of the present invention is obtained by converting an aromatic vinyl monomer and butadiene with an organic alkali metal or organic alkaline earth metal catalyst, using a vinylating agent or the like as an ether or tertiary amine. It can be obtained by a conventionally known anionic polymerization using a Lewis base such as For example, in the polymerization system before the start of polymerization, butadiene alone is put as a monomer, and the amount of the aromatic vinyl monomer in the unreacted monomer in the polymerization reaction solution is gradually changed from the start of the polymerization, or The aromatic vinyl monomer is added until the end of the polymerization so as to increase continuously. The polymerization temperature is preferably from -80 to + 120 ° C, more preferably from 0 to 110 ° C, and from 20 to 100 ° C.
C is particularly preferred. In the present invention, the component (a)
The copolymer rubber may contain a copolymerizable monomer with an aromatic vinyl monomer and butadiene as long as the effects of the present invention are not impaired.

As the polymerization solvent, any of the solvents conventionally used for the above-mentioned anionic polymerization of an aromatic vinyl monomer and butadiene can be used. The solvent is not particularly limited as long as the solvent does not dissolve the coalescence. For example, n-pentane, n-hexane, cyclohexane, toluene, n-heptane and the like can be mentioned. These may be used in combination of two or more.

As the organic alkali metal, for example, n-
Organic lithium compounds such as butyllithium, sec-butyllithium, t-butyllithium, and phenyllithium;
Organic sodium compounds such as sodium naphthalene; and organic potassium compounds such as potassium naphthalene. Examples of the organic alkaline earth metal include organic magnesium compounds such as n-butyl magnesium and n-hexyl magnesium; organic calcium compounds such as ethoxy calcium and calcium stearate; and organic barium compounds such as ethoxy barium. These are 2
More than one species may be used in combination. Of these, organolithium compounds are preferred.

In the copolymer rubber of the component (a) of the present invention, the average amount of the bonded aromatic vinyl monomer is 10 to 40% by weight, preferably 15 to 30% by weight. When the average amount of the bonded aromatic vinyl monomer is too large, the dynamic magnification does not decrease even when the polybutadiene rubber of the component (b) or the diene rubber of the component (c) is blended, though the loss coefficient at room temperature is large. In addition, the low-temperature anti-vibration characteristics may be insufficient.
On the other hand, when the average amount of the bonded aromatic vinyl monomer is too small, the loss coefficient at room temperature is small, and it is difficult to obtain a sufficient vibration damping effect. The copolymer rubber of the component (a) has a 1,2 bond content in all butadiene units of 50% by weight or more, preferably 60% by weight or more. If the content of the 1,2 bond is too small, the compatibility of the component (b) and the component (c) with the rubber may be deteriorated, and the durability and low-temperature protection while maintaining the excellent vibration damping effect at room temperature may be maintained. It becomes difficult to improve the vibration characteristics.

Further, in the copolymer rubber of the component (a),
The amount of bound aromatic vinyl monomer is distributed in the polymer chain such that it increases or decreases from one end of the polymer chain to the other. At very short chain lengths, the tendency of increase or decrease may be reversed, but the tendency of increase or decrease from one end to the other is uniform and does not reverse as a whole.

The distribution (tapering degree) of the amount of the bound aromatic vinyl monomer is such that the amount of the bound aromatic vinyl monomer is equal to the average amount of the bound aromatic vinyl monomer in the portion from one end of the polymer chain to 10% by weight of the molecular chain length. It is preferably at most 以下 of the amount of the monomer, more preferably at most ５ of the amount of the monomer. The amount of the monomer is preferably at least 1.5 times, more preferably at least 2 times, the amount of the average bound aromatic vinyl monomer. If the amount of the bound aromatic vinyl monomer at the end is too small or too large, the compatibility of the component (b) and the component (c) with the rubber may be deteriorated, resulting in durability and vibration proof at low temperature. It becomes difficult to improve the characteristics.

In the present invention, the use of a copolymer rubber having an amino group and / or a substituted amino group as the copolymer rubber of the component (a) balances the vibration-proof and sound-proof properties of the vibration-proof rubber. It is preferable because it can be further improved. The method for introducing an amino group and / or a substituted amino group into the copolymer rubber of the component (a) is not particularly limited. For example, when an aromatic vinyl monomer and butadiene are copolymerized, an aromatic vinyl monomer may be used. Of copolymerizing the above-mentioned amino group-containing aromatic vinyl monomer and amino group-free aromatic vinyl monomer in combination, amino group-free aromatic vinyl monomer, butadiene and copolymerization thereof Examples include a method of introducing a monomer other than an aromatic vinyl monomer having a possible amino group and / or substituted amino group by copolymerization, such as a method of copolymerizing a monomer.

As another method, for example, the living copolymer rubber of the component (a) and (A) a compound having a bond represented by the following general formula (1) in a molecular chain, and (B) an amino group and And / or a modification method of reacting with at least one compound selected from benzophenones and thiobenzophenones having a substituted amino group. In order to further enhance the effects of the present invention, it is preferable to introduce the group by a modification method.

[0018] (X in the formula is an oxygen atom or a sulfur atom.) The modification method will be described in detail at the end.

Component (b) of the present invention is a polybutadiene rubber. As polybutadiene rubber, high cis-1,
Both 4-polybutadiene rubber and low cis-1,4 polybutadiene rubber (produced by the same anionic polymerization as the copolymer rubber of the component (a)) can be used. The polybutadiene rubber of the component (b) is also preferably modified similarly to the copolymer rubber of the component (a). The use of the polybutadiene rubber suppresses the durability of the vibration isolating rubber, particularly, the growth of cracks generated during use.

As the rubber of the component (c) in the present invention, any diene rubber can be used as long as it is a diene rubber other than the components (a) and (b), and is not particularly limited. As the diene rubber of the component (c), for example,
Natural rubber (NR), polyisoprene rubber (IR), copolymer rubber of butadiene with an aromatic vinyl monomer other than the copolymer rubber of component (a) (for example, random SBR), acrylonitrile-butadiene copolymer rubber (NBR) ), Ethylene-propylene copolymer rubber (EPM, EPDM) and the like, and these can be used alone or in combination of two or more. Of these, natural rubber, polyisoprene rubber, and random SBR are preferred. Particularly preferred are natural rubber and polyisoprene rubber, which can improve the vibration durability and the anti-vibration characteristics at low temperatures.

The Mooney viscosities (ML _{1 + 4} , 100 ° C.) of these component rubbers (a) to (c) are usually about 10 to 200, preferably 30 to 100, more preferably 45 to 100.
80. If the Mooney viscosity after oil extension is within the above range, these rubbers can be used as oil-extended rubber regardless of Mooney viscosity before oil extension.

The proportions of the component rubbers of the components (a), (b) and (c) in the composition for rubber vibration insulators of the present invention are as follows:
The copolymer rubber of the component (a) is 5 to 90% by weight, preferably 20 to 70% by weight, and the polybutadiene rubber of the component (b) is 5 to 90% by weight, preferably 20 to 70% by weight. 5 to 90% by weight, preferably 25 to 75% by weight, more preferably 35 to 65% by weight of the diene rubber of (c).
% By weight. By blending each of the component rubbers in the above proportions, it is possible to produce a vibration-proof rubber having excellent balance between vibration-proof and sound-proof at room temperature, and further having excellent durability and low-temperature characteristics. Is possible.

If the proportion of the copolymer rubber of the component (a) in the rubber component is too small, it is difficult to maintain the excellent vibration-proofing properties of the copolymer rubber at room temperature. The effect of improving the anti-vibration characteristics in the above is reduced. If the proportion of the polybutadiene rubber used as the component (b) is too small, it is difficult to suppress the durability, particularly crack growth, and if it is too large, the strength tends to decrease. or,
If the proportion of the diene rubber used as the component (c) is too small, the improvement in the low-temperature properties becomes insufficient, and if it is too large, it becomes difficult to maintain a balance between vibration damping and soundproofing.

The composition for vibration-proof rubber of the present invention can be obtained by mixing and kneading the above-mentioned rubber component and various compounding agents using a commonly used mixer such as a roll or a Banbury. In the present invention, as the compounding agent, any compounding agent conventionally used in the production of a vibration-proof rubber can be used, and the type and amount of the compounding agent are not particularly limited, and are required for the vibration-proof rubber. It can be appropriately determined so as to satisfy the performance. The above-mentioned component rubbers may be used after being mixed in advance, or may be mixed and kneaded with a compounding agent at a predetermined ratio when preparing the composition.

Commonly used compounding agents include vulcanizing agents, vulcanizing aids, vulcanizing accelerators, reinforcing agents, fillers, softeners, processing aids,
Antioxidants, antiozonants, and the like. The compounding amount of these compounding agents is usually based on 100 parts by weight of the rubber component.
For example, vulcanizing agent 0.3 to 20 parts by weight, vulcanization accelerator 0.1
0 to 10 parts by weight, 0 to 100 parts by weight of a reinforcing agent and / or a filler, 0 to 100 parts by weight of a softening agent, 0.1 to 5 parts by weight of an antioxidant.

Examples of the vulcanizing agent include sulfur, sulfur donating compounds such as tetramethylthiuram disulfide, and peroxides such as dicumyl peroxide. The rubber component (c) includes natural rubber and polyisoprene rubber. When a diene rubber such as that described above is used, sulfur is preferred from the viewpoint of durability. A vulcanization aid such as zinc white or stearic acid is usually used together with the vulcanizing agent. As the vulcanization accelerator, for example, vulcanization accelerators of guanidine type, thiazole type, sulfenamide type, thiuram type, dithioate type, thiourea type and the like are usually used.

As the reinforcing agent, for example, FEF or SRF
And the like, carbon black, silica, clay and the like. Among them, carbon black is preferred. Examples of the filler include calcium carbonate, magnesium silicate and the like. Examples of the softening agent include aromatic oils, naphthenic oils, extender oils such as process oils such as paraffin oils, and plasticizers such as dioctyl phthalate.From the viewpoint of processability, aromatic oils and Naphthenic oils are preferred.

As the anti-aging agent, for example, poly-
Amine-ketones such as (2,2,4-trimethyl-1,2-dihydroquinone); amines such as N-phenyl-N'-isopropyl-p-phenylenediamine;
Examples of the phenolic antioxidant such as 2'-methylenebis (4-ethyl-6-t-butylphenol) include waxes such as paraffin wax and carnauba wax.

The composition for a vibration-proof rubber of the present invention obtained by mixing and kneading each of the above-mentioned compounding ingredients and a rubber component is molded and vulcanized by a method usually used in the production of a vibration-proof rubber to prevent the composition. Vibration rubber is manufactured. By using the anti-vibration rubber composition of the present invention, an automobile engine mount (front and rear), an engine sight mount, a torque rod, a wind stopper, a side mount buffer, a damper mount (front and rear), a lower arm bush, and a radius rod. It is possible to manufacture anti-vibration rubber such as a bush (front and rear), a stabilizer bush, and a bumper stopper (front and rear).

The method for modifying the copolymer rubber of the component (a) and the polybutadiene rubber of the component (b) will be described below. Modifications can be made to polymer chain ends and / or backbone. Component (a) obtained by the aforementioned anionic polymerization
Of the copolymer rubber and the polybutadiene rubber of the component (b)
As long as the polymerization reaction is not terminated by adding a polymerization terminator such as alcohols such as methanol or ethanol or water, the above-mentioned catalytic metal having activity is bonded to the terminal of the polymer chain, so-called living polymer. . When the terminal is modified, an organic compound having an active terminal metal of the living polymer and (A) a bond represented by the following general formula (1) (where X represents an oxygen or sulfur atom) in a molecular chain; (B) It may be reacted with at least one compound selected from benzophenones and thiobenzophenones having an amino group and / or a substituted amino group. (In the formula, X is an oxygen atom or a sulfur atom.)

Compound (A) having a bond of the general formula (1)
Is not particularly limited as long as it is a compound having the above bond in the molecule and reacting with the living copolymer rubber. For example, formamide, N, N-dimethylformamide,
N, N-diethylformamide, acetamide, N, N
-Dimethylacetamide, N, N-diethylacetamide, aminoacetamide, N, N-dimethyl-N ',
N'-dimethylaminoacetamide, N ', N'-dimethylaminoacetamide, N'-ethylaminoacetamide, N, N-dimethyl-N'-ethylaminoacetamide, N, N-dimethylaminoacetamide, N-phenyldiacetamide , Acrylamide, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, propionamide, N, N-dimethylpropionamide, 4-pyridylamide,

N, N-dimethyl-4-pyridylamide,
Benzamide, N-ethylbenzamide, N-phenylbenzamide, N, N-dimethylbenzamide, p-
Aminobenzamide, N ', N'-(p-dimethylamino) benzamide, N ', N'-(p-diethylamino) benzamide, N '-(p-methylamino) benzamide, N'-(p-ethylamino) Benzamide,
N, N-dimethyl-N '-(p-ethylamino) benzamide, N, N-dimethyl-N', N '-(p-diethylamino) benzamide, N, N-dimethyl-p-aminobenzamide, N-methyl Dibenzamide, N-acetyl-N-2-naphthylbenzamide, succinamide, maleamide, phthalamide, N, N,
N ', N'-tetramethylmaleamide, N, N,
N ', N'-tetramethylphthalamide, succinimide, N-methylsuccinimide, maleimide, N-methylmaleimide,

Phthalimide, N-methylphthalimide,
Oxamide, N, N, N ', N'-tetramethyloxamide, N, N-dimethyl-p-amino-benzylacetamide, nicotinamide, N, N-diethylnicotinamide, 1,2-cyclohexanedicarboximide, N-
Methyl-1,2-cyclohexanedicarboximide, methyl carbamate, N-methyl-methyl carbamate,
Amides and imides such as N, N-diethyl-ethyl carbamate, ethyl carbanilate, p-N, N-diethylamino-ethyl carbanilate; urea, N, N'-dimethylurea, N, N, N ', N'-tetramethylurea,
Ureas such as 1,3-dimethylethylene urea, N, N'-diethyl propylene urea, N-methyl-N'-ethyl propylene urea; formanilide, N-methylacetanilide, aminoacetanilide,

Benzanilide, p, p'-di (N, N-
Anilides such as diethyl) aminobenzanilide; δ
-Caprolactam, ε-caprolactam, N-methyl-
ε-caprolactam, N-acetyl-ε-caprolactam, N-vinyl-ω-laurylolactam, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-acetyl-2-
Pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, 2-piperidone, N-methyl-2
-Piperidone, N-vinyl-2-piperidone, N-phenyl-2-piperidone, 2-quinolone, N-methyl-2
Lactams such as quinolone, 2-indolinone, N-methyl-2-indolinone; 3-diethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazoline dinone, 1-methyl-3- (2- Methoxyethyl)-
Imidazolidinones such as 2-imidazolidinone; isocyanuric acids such as isocyanuric acid and N, N ', N'-trimethylisocyanuric acid; and the corresponding sulfur-containing compounds. Particularly preferred compounds are compounds in which an alkyl group is bonded to nitrogen.

The benzophenones or thiobenzophenones (B) having an amino group and / or a substituted amino group include, for example, 4-aminobenzophenone, 4-dimethylaminobenzophenone, 4-dimethylamino-4'-
Methylbenzophenone, 4,4'-diaminobenzophenone, 4,4'-bis (dimethylamino) benzophenone, 4,4'-bis (diethylamino) benzophenone, 4,4'-bis (ethylamino) benzophenone,
3,3'-dimethyl-4,4'-bis (diethylamino) benzophenone, 3,3'-dimethoxy-4,4 '
-Bis (dimethylamino) benzophenone, 3,3 ',
5,5'-tetraaminobenzophenone, 2,4,6-
Triaminobenzophenone, 3,3 ', 5,5'-tetra (diethylamino) benzophenone, and the like, and their corresponding thiobenzophenones. As the substituted amino group, those having an alkyl group are preferable, and a dialkyl-substituted amino group is particularly preferable. Substituents other than the amino group and substituted amino group may be present as long as they do not adversely affect the reaction.

The amount of the above compound to be reacted with the living copolymer rubber or the like may be equimolar or slightly excess with respect to the amount of the metal (the above-mentioned catalyst metal) added to the copolymer rubber or the like. After the reaction, the active metal at the terminal is removed by adding a coagulant which is also a polymerization terminator such as methanol to the reaction solution, or by coagulating steam by blowing steam to react with water which is also a polymerization terminator. Thus, a terminal-modified copolymer rubber or the like in which the above compound is bonded to the polymer chain terminal is obtained. In the present invention, the alkali metal and / or the alkaline earth metal are added to the copolymer rubber of the component (a) and the polybutadiene rubber of the component (b) after the termination of the polymerization, and are reacted with the above compound. The main chain of the polymer can also be modified. If a terminal-modified copolymer rubber or the like is used, both the terminal and the main chain can be modified.

Another method of modifying the main chain is to polymerize the copolymer rubber of the component (a) or the polybutadiene rubber of the component (b) with 2-N, N-dimethylaminostyrene, 4-N, N
-Dimethylaminostyrene, 2-N, N-dimethylaminomethylstyrene, 4-N, N-dimethylaminomethylstyrene, N, N-dimethylaminoethylstyrene, aminostyrene, 2-vinylpyridine, 4-vinylpyridine, Amino-containing aromatic vinyl monomers such as -vinyl (N, N-diisopropylbenzamide) and 4-vinyl (N, N-diisopropylbenzamide) and / or other amino group-containing monomers. This is a method in which a monomer containing aromatic vinyl alone and butadiene are copolymerized.
The rubber having both the main chain and the terminal modified can be obtained also by reacting the above-mentioned compound with a living polymer of the rubber.

The Mooney viscosity (ML _{1 + 4} , 100 ° C.) of the terminal and / or main chain modified rubber of component (a) or component (b) used in the present invention is usually about 10 to 200,
Preferably it is 80-100, More preferably, it is 45-80. If the Mooney viscosity after oil extension is within the above range, these component rubbers can be oil-extended and used regardless of the Mooney viscosity before oil extension.

The average amount of the aromatic vinyl monomer bonded to the aromatic vinyl monomer butadiene copolymer rubber and the 1,2 bond content in all butadiene units in the present invention can be determined by the Hampton method (infrared spectroscopy). Hampton, Anal.Chem., Vol.21,9
23 (1949)).

[0040]

The present invention will be described more specifically below with reference to examples and comparative examples. The parts and percentages in the following examples are based on weight unless otherwise specified. In addition, tests for vibration isolation performance and the like in the following examples are as follows.

(1) Dynamic characteristics Hydraulic servo dynamic characteristic tester (EFH-20 manufactured by Sagimiya Seisakusho)
−50-2.5), the loss tangent (tan δ) at 23 ° C. and 15 Hz and the dynamic elastic modulus (K _d ) at 23 ° C. and 100 Hz were measured. divided by the _{K s) (K d / K} s), i.e., calculates the dynamic magnification. The measurement sample was a rubber vulcanizate having a diameter of 1 inch and a height of 2 inches in a columnar shape. The tan δ and K _d were initially 2 mm compressed by a dynamic servo, and ± 15 at 15 Hz. The measurement was performed by giving an amplitude of 0.5 mm and an amplitude of ± 0.05 mm at 100 Hz. K _s is the displacement of the height of the sample is to compress at a rate of 1 mm / 15 seconds so that 2 mm, a compressed state depressurized after holding 30 seconds to restore the displacement 0 mm. This cycle is repeated three times, and the displacement during the third compression is 1
The modulus of elasticity was determined from the compressive stress in the range from 2 mm to 2 mm. The larger the tan δ and the smaller the K _d / K _s (dynamic magnification), the better the vibration and soundproofing properties.

(2) Durability Test A constant elongation fatigue test was performed using a Demasher bending tester.
In the constant elongation fatigue test, a B-type dumbbell described in JIS-K6301 is attached to a demasher bending tester so that the elongation ratio becomes 100%, and reciprocated at 23 ° C. at 300 times / minute, and the number of times of breakage is measured. 2.03mm flex crack growth
The test piece was bent in the same manner as described above except that the test piece having the crack was used, and the length of the crack after 10,000 reciprocating motions was measured. The greater the number of times of fracture, the smaller the length of the crack, the better the durability.

(3) Physical properties in normal state Tensile strength (MPa), elongation at break (%), hardness (point) according to JIS K6301 (JIS spring type A)
Using a mold hardness tester).

Examples 1-4, Comparative Examples 1-5 The terminally modified tapered S used in this example and Comparative Example 4
BR (average bound styrene content 20%, 1,2 bond content in all butadiene units 65%, Mooney viscosity (ML _{1 +} 4,1
(00 ° C.) 62) (SBR1) was prepared by the following method. In an autoclave with a stirrer having an internal volume of 15 liters, 8 kg of cyclohexane, 75 g of styrene, 1,3-
925 g of butadiene and 24 mmol of N, N, N ', N'-tetramethylethylenediamine were charged, and a cyclohexane solution containing 18 mmol of n-butyllithium was added, and polymerization was started at 40 ° C. Ten minutes after the start of the polymerization, 80 g of styrene and 520 of 1,3-butadiene
g of the mixture is added continuously over 20 minutes, then a mixture of 150 g of styrene and 150 g of 1,3-butadiene is added continuously over 15 minutes, and finally 100 parts of styrene are added.
g was added continuously over 15 minutes.

A portion of the reaction mixture was sampled at the time when 10% of all the monomers used had been polymerized from the start of polymerization (the portion forming one end of the total polymer chain length of 10%), and the resulting polymer was bound. When the amount of styrene was analyzed by infrared spectroscopy, it was 6.3%. Further, at the time when 90% of all the monomers used are polymerized and at the time when 100% are polymerized, the other end 10 of the total polymer chain length obtained from the difference in the amount of bound styrene of the sampled polymer, respectively.
The amount of bound styrene in the% portion was 48.9%.

After confirming that the polymerization conversion reached 100%, 1 mmol of tin tetrachloride was added and reacted for 20 minutes, and then 20 g of 1,3-butadiene was added to add 1 mmol.
After reacting for 0 minutes, 10 mmol of 4,4'-bis (diethylamino) benzophenone was added and reacted for another 30 minutes. After completion of the reaction, the reaction was stopped by adding 20 mmol of methanol. 2,6-di-
20 g of t-butyl-p-cresol (BHT) was added,
The modified SBR produced by steam stripping was coagulated, dehydrated with a dehydrating roll, and dried under reduced pressure at 60 ° C. for 24 hours.

In this example, as the polybutadiene rubber of the component (b), a terminal-modified polybutadiene rubber (Nipol BR1250 manufactured by Zeon Corporation, content of 1,2 bonds: 10%, Mooney viscosity (ML _{1 + 4} , 100 ° C.)) 45) (B
R1) and high cis polybutadiene rubber (Nipol BR1220 manufactured by Nippon Zeon Co., Ltd. (cis 1,4 bond content 9)
8%, Mooney viscosity (ML _{1 + 4} , 100 ° C) 43) (BR
2) was used. For comparison with the copolymer rubber of the component (a), a conventional emulsion polymerization SBR (Nipol manufactured by Zeon Corporation) was used.
1502: random SBR, average bound styrene content 2
3.5%, Mooney viscosity (ML _{1 + 4} , 100 ° C) 52) (S
BR2) was used.

According to the formulation shown in Table 1, the rubber component and a compounding agent other than the vulcanizing agent were mixed and kneaded with a Banbury mixer (0.8 liter), and the resulting mixture and the vulcanizing agent were rolled. The mixture was mixed and kneaded to prepare a vulcanizable rubber composition. Specimens (thickness 2) for measurement of physical properties and durability under normal conditions
mm sheet) was prepared by press vulcanization at 160 ° C. for 15 minutes. A test piece for measuring vibration isolation characteristics (a cylindrical block having a height of 2 inches and a radius of 1 inch) was placed at 160 ° C. × 20.
And press vulcanization. Table 1 shows the evaluation results measured based on these test pieces.

[0049]

[Table 1] (Note) (1) Seat SO (DBP manufactured by Tokai Carbon Co., Ltd.)
Refueling amount (Method A) 115ml / 100g, iodine adsorption amount 4
(2) Fukko Flex # 1 manufactured by Fujikosan Co., Ltd. (3) Noxeller CZ manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

The most common formulation in the prior art is Comparative Example 1. Here, the effects of the present invention will be described with reference to Comparative Example 1. Comparative Example 1 was different from Example 1 in that random SBR was used and polybutadiene rubber was not used.
Due to this difference, the first embodiment has excellent anti-vibration characteristics. The comparison between Comparative Example 4 and Example 4, which are the same as above, also shows that Example 4 is excellent in the anti-vibration characteristics.
Comparative Example 2, which differs from Example 1 only in that random SBR is used, is inferior to Example 1 particularly in terms of dynamic magnification. Comparative Example 3, which is different from Example 1 only in that no polybutadiene rubber is used, has improved vibration-proof properties compared to Comparative Example 1, but is inferior to Example 1. Furthermore, as is clear from the results in Table 1, it can be seen that the present invention significantly improves the dynamic magnification.

[0051]

According to the present invention described above, there is provided an anti-vibration rubber having a good balance between soundproofing and vibration-proofing properties and further excellent durability. Such anti-vibration rubbers include an automobile engine mount (front and rear), an engine sight mount, a torque rod, a wind stopper, a side mount buffer, a damper mount (front and rear), a lower arm bush, a radius rod bush (front and rear), and a stabilizer bush. , Bumper stoppers (front and rear), etc.

A preferred embodiment of the present invention is as follows. (1) In claim 1, the copolymer rubber (a) has an amino group and / or a substituted amino group. (2) The copolymer rubber (a) according to claim 1 or (1).
Is a copolymer rubber of a living aromatic vinyl monomer having an active terminal and butadiene, and (A) a compound represented by the following general formula (1)
And (B) a reaction product with at least one compound selected from benzophenones and thiobenzophenones having an amino group and / or a substituted amino group. (X in the formula is an oxygen atom or a sulfur atom.) (3) In claim 1 or (1) or (2), the copolymer rubber (a) has an average bonded aromatic vinyl monomer amount of 15 to 15. 3
0% by weight, the content of 1,2 bonds in all butadiene units is 6
0% by weight or more. (4) In any one of claims 1, (1) to (3), the aromatic vinyl monomer is styrene. (5) In any one of claims 1, (1) to (4), (a) is 20 to 70% by weight, more preferably 30 to 70% by weight.
60% by weight, (b) is 5 to 65% by weight, more preferably 5 to 35% by weight, and (c) is 25 to 75% by weight, more preferably 35 to 65% by weight. (6) In any one of claims 1 (1) to (5), the polybutadiene rubber is a high cis polybutadiene rubber or a terminal-modified low cis polybutadiene rubber. (7)
In any one of claims 1, (1) to (6),
(C) is at least one diene rubber selected from natural rubber, polyisoprene rubber, polybutadiene rubber, and random styrene-butadiene copolymer rubber.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI F16F 15/08 F16F 15/08 D

Claims (2)

[Claims] 1. A copolymer rubber of (a) an aromatic vinyl monomer and butadiene, wherein the average amount of the bonded aromatic vinyl monomer is 10 to 40% by weight, and 1,2 bonds in all butadiene units. An aromatic vinyl monomer-butadiene copolymer rubber having a content of 50% by weight or more and an amount of a bonded aromatic vinyl monomer increasing or decreasing from one end to the other end along the polymer molecular chain; % And (b) polybutadiene rubber 5 to 95
A composition for a vibration-proof rubber, comprising: a rubber component comprising (c) 5 to 90% by weight of a diene rubber other than the above (a) and (b) and a compounding agent. 2. An anti-vibration rubber obtained by molding and vulcanizing the composition according to claim 1.