JPS58176229A - Vibration-damping rubber composition - Google Patents

Abstract

PURPOSE:To form a rubber composition having a lowered damping ratio, an increased loss tangent and excellent low-temperature resistance, by blending a specified styrene/butadiene copolymer rubber. CONSTITUTION:Above 30pts.wt. styrene/butadiene copolymer rubber with a bound styrene content of 20-50wt%, 1,2-bond content of the butadiene portion of 20-60% and glass transition point >=-55 deg.C, is blended with below 70pts.wt. other rubber (e.g., natural rubber, polybutadiene rubber) in a plastomill, roller or the like. A rubber composition having a still further improved vibration- damping property can be obtained by using, as the above styrene/butadiene copolymer rubber, a copolymer rubber at least 20wt% of which consists of a copolymer having a bond between carbon and a metal such as Si, Ge or Sn in the molecular chain.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vibration-proof rubber composition having excellent vibration absorption properties and cold resistance.

Generally, so-called anti-vibration rubber is used to prevent noise and vibration from transportation means such as automobiles and motorcycles, and industrial machinery.

Properties required of anti-vibration rubber include vibration absorption properties and cold resistance. As vibration absorption characteristics, (1) it must be hard enough to support large static loads; (2) it must be hard enough to support large static loads;
When subjected to a dynamic load of 00 Hz or higher, the transfer coefficient of external force to the clothing is small, and (3) loss tangent (tan δ) is required to be evaluated, but as a parameter expressing both characteristics (1) and (2), Generally, a static-dynamic ratio (dynamic spring constant at 100 Hz/static shear modulus: E' 100 Hz/Gs) is used.

It can be said that the smaller the static-dynamic ratio and the higher the loss tangent, the better the vibration damping characteristics.

On the other hand, the operating temperature of anti-vibration rubber is expanding, and cold resistance is also a necessary characteristic for anti-vibration rubber.

Cold resistance is evaluated, for example, at the temperature (T2) at which the specific modulus of the JIS K6301 low-temperature torsion test is 2, and it can be said that the lower T2 is, the better the cold resistance is. There are limits to how these relationships can be improved with compounding agents, and it is hoped that a polymer with excellent anti-vibration properties and cold resistance will emerge. In order to reduce the static-dynamic ratio, it is necessary to lower the bound styrene content and/or to lower the 1.2 bound metal content of 72217 parts, but this also results in a reduction in the loss tangent. Until now, no polymer has existed that provides a balanced static-to-dynamic ratio and loss tangent. Regarding cold resistance, it is desirable to lower the glass transition temperature, but in this case the loss tangent becomes smaller, which is not preferable.

An object of the present invention is to provide an anti-vibration comb that has excellent anti-vibration characteristics and excellent cold resistance by reducing the static-dynamic ratio and increasing the loss tangent. The present invention has a bound styrene content of 20 to 50% by weight, a content of 1.2 bound metal in the butadiene moiety of 20% to less than 60%, preferably 30% to less than 60%, and a glass transition temperature of -55°C. The above styrene-butashev copolymer rubber is used as a rubber component
The present invention relates to a vibration-proof rubber composition containing 30 parts by weight or more in 0 parts by weight.

The copolymer rubber of the present invention includes, for example, styrene and butadiene/
is obtained by anionic polymerization using an organolithium compound (e.g. alkyl lithium) as a polymerization initiator and a Lewis base such as ether or tertiary amine as a promoter. used. As the solvent, a solvent inert to the organic lithium compound is used, and toluene, benzene, nclohexane, heptane, hexa/, etc. are preferably used. Such polymerization method and conditions are described in detail in, for example, Japanese Patent Application No. 16255-1982.
1 (filed on November 20, 1980). The microstructure of the above-mentioned copolymer depends on the type and amount of Lewis base, or when the amount % is exceeded, or when the 1.2 bond content of the butadiene moiety is 60% or more, the loss tangent is high, but the static-dynamic ratio is It has a large angle and poor cold resistance. When the bound styrene content is less than 20% by weight and the 1.2 bound metal content of 72217 parts is less than 20%, the static-dynamic ratio is small, but the loss tangent is also small. If the glass transition temperature is lower than 155° C., the static-dynamic ratio and cold resistance are both good, but the loss tangent is also small, making it impossible to obtain a vibration-proof rubber composition with a well-balanced vibration-proofing property and cold resistance.

According to the invention, the bound styrene content is 1 of 72217 parts.
．． Rubber compositions with excellent vibration damping properties can be obtained by controlling the content of two-bond metal and the glass transition temperature If. By containing a polymer having at least one type of metal-carbon bond, even better vibration damping properties can be obtained.

The proportion is not particularly limited, but is preferably 20% by weight or more.

In order to contain a polymer having a bond between at least one of silicon, germanium, and tin and carbon in the main chain of the molecule, for example, the terminus of the living polymer produced in the anionic polymerization using the lithium catalyst and the halogen Obtained by coupling reaction with compound. Examples of chlorides include tin dichloride, silicon tetrachloride, silicon tetrabromide,
Examples include tin tetrachloride, tin tetrabromide, and germanium tetrachloride.

The styrene-butadiene copolymer rubber of the present invention may be used in combination with other rubbers, such as natural rubber and diene-based synthetic rubber. As the diene synthetic rubber, polyisobre/rubber, styrene-getadiene rubber and polybutadiene rubber are preferred.

When used in admixture with other rubbers, the proportion of the styrene-putadier/copolymer rubber of the present invention in 100 parts by weight of the rubber component ranges from at least 30 parts by weight. If the styrene rubber/copolymer rubber of the present invention is less than 30 parts by weight, vibration damping properties will not be sufficiently exhibited.

The rubber composition of the present invention has a number average molecular weight of 2,000 to 10
0,000 of a liquid polymer (eg, low molecular weight polyptadiene/low molecular weight polyinoprene; microstructure does not matter) can be added. Additionally, it can be used as a vulcanized product containing known additives for various anti-vibration rubber applications.

In the examples, the bound styrene content and the microstructure of the butadiene moiety are determined by the infrared absorption method of the polymer having a bond between metal and carbon. It is determined from the peak area of Further, the glass transition temperature was measured by a differential scanning calorimetry method under a heating rate of 20° C./min, the cold resistance (T2) was measured by a low temperature torsion test according to JIS K6301, and the Mooney viscosity was measured according to JIS K6300.

Anti-vibration characteristics are determined by static shear modulus G according to JISK6301.
s was determined and the dynamic spring constant (E'1OOH
z) and loss tangent, and calculate the static-dynamic ratio (E'1ooHz/G
s) was calculated and evaluated based on the static-dynamic ratio and the magnitude of the loss tangent.

Next, the present invention will be explained in more detail with reference to the following examples and comparative examples.

Examples 1 to 8 and Comparative Examples 1 to 6: The styrene/-Putadier/copolymer rubber of Examples 1 to 5 and Comparative Examples 3 to 6 was polymerized under the polymerization conditions shown in Table 4 using a 5t autoclave purged with nitrogen. obtained. Polymer A~
In the case of G, polymerization is performed without removing the reaction heat, and polymer H
, I, the polymerization was carried out at constant temperature. Also, polymer E,
For F, after confirming 100% polymerization conversion, 57% butadiene was added, and then 0.2 t/1Oc of tin tetrachloride was added.
c Cyclohexane was added. 2°4-ge after 30 minutes
A methanol solution of 3v of t-butylcatechol was added to stop the reaction.

Polymerization conversion rate 100 for polymers A-D and G-H
Immediately after confirming the %, a methanol solution 5 of 2.4-di-t-butylcatechol 3f was added to stop the reaction.

After removing the solvent, it was dried with a roll at 100°C to obtain a polymer.

Examples 1 to 6 and Comparative Examples 1 to 6 were prepared according to Table 2, and Examples 7 and 8 were prepared using Plastomil and 60 according to the formulations shown in Table 3.
The mixture was kneaded using a Type 1 roll machine. Natural rubber is 150℃×
The physical properties of the vulcanized rubber obtained by press vulcanization for 10 minutes and press vulcanization at 150°C for 30 minutes were measured, and the results are shown in Table 4.

Table 2 Formulation list (parts by weight) Polymer 100 FEF carbon 30 Zinc white 5 Stearic acid 1 Vulcanization accelerator CZ old 2 Sulfur 2 Cyclohexylube/sothiazole sulfenamide polymer 100 FEF carbon 30 Plasticizer or liquid polymer 10 Zinc white 5 Stearic acid 1 Vulcanization accelerator CZ 2 Sulfur 2 *+ R8S#1 *2 Solution polymerization SBR *1 Phthalate ester 10 phr addition *4 Polybutadiene rubber with number average molecular weight 5,000 10 phr addition * 5 Content of polymer having metal and carbon bonds in the main chain *6 Glass transition temperature *F M Ll+4 (1o o
°C) *8 Dynamic spring constant (E'+00 ”Z)
and static shear modulus (Gs): E'+oo 7'
Z/Gs: The smaller the better *9 Loss tangent 20°C, 15 R2: The better it is *10 Low temperature torsion test, temperature at which the specific modulus becomes 2:
The lower the temperature, the better the cold resistance *l From the results of Molecular Characteristic Table-4 of Tsuta Polymer D, the styrene-butadiene copolymer rubber of the present invention is natural rubber, the commercially available solution polymerized styrene-butadiene copolymer, and the comparative example styrene-butadiene copolymer rubber. It can be seen that a vibration-proof rubber composition with a better balance of static-dynamic ratio, loss tangent, and cold resistance than polymers can be provided.

Procedural amendment (method) October 12, 1986 FO 57 Commissioner of the Japan Patent Office Kazuo Wakasugi 1. Special indication of the case - No. 57-60572 2. Name of the invention: anti-vibration fm composition 3. Person making the amendment Relationship to the case Patent applicant address: 2-11-24 Tsukiji, Chuo-ku, Tokyo Name (417) Nippon Gosei f5 Co., Ltd. 4, Agent address: Toranomon, 2-8-1 Toranomon, Minato-ku, Tokyo Electric Pill September 28, 1980 6, Detailed Description of the Invention column and Power of Attorney L of the specification to be amended ill Contents of the amendment Ill Correct the 10th and 12th pages of the specification as shown in the attached sheet.

(2) Supplement the attached power of attorney.

Claims (3)

[Claims] (1) The bound steel content is 20 to 50% by weight, the 1.2 bound metal content of the butadiene moiety is 20% or more and less than 60%,
1. A vibration-proof rubber composition comprising 30 parts by weight or more of a styrene-butadiene copolymer rubber having a glass transition temperature of 155° C. or more in 100 parts by weight of the rubber component. (2) The anti-vibration rubber composition according to claim 1, wherein the butadiene moiety has a 12-bond content of 30% or more and less than 60%. (3) The claim that the styrene-butadieno copolymer rubber contains at least 20% by weight of a copolymer having a bond of at least one metal selected from silicon, germanium, and tin with carbon in its molecular chain. The anti-vibration rubber composition according to item 1 or 2.