JP2697863B2 - Anti-vibration rubber composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an anti-vibration rubber composition having good anti-vibration rubber performance and improved durability. More specifically, the present invention uses a modified styrene-butadiene random copolymer and a natural rubber as raw rubbers, and forms a vulcanized rubber composition blended with carbon black to provide a vibration-proof rubber required as a vibration-proof rubber. The present invention relates to an anti-vibration rubber composition having good performance and soundproofing performance, and having improved durability in long-term use.

[Conventional technology]

Absorbs or reduces various vibrations and sounds generated from the engine, power transmission, undercarriage rotation and drive components of the automobile, holds the components in place, fully expresses their functions, and is unpleasant. 2. Description of the Related Art In order to improve the riding comfort of an automobile by eliminating vibration and noise, various parts of the automobile use anti-vibration rubbers having various shapes and performances. Conventionally, vulcanized rubber compositions using natural rubber or natural rubber and other diene-based rubber as raw rubber have been mainly used for these vibration-proof rubbers.

In recent years, the temperature inside the engine room has risen due to trends such as higher output, higher speed, and restriction of air inflow into the engine room to reduce air resistance, and vibration-proof rubber such as engine mounts Due to the use of higher temperature than before, the space saving and the increase of various parts around the engine, the vibration-isolating rubber must be smaller in shape and bear the same or higher load as before. In addition, anti-vibration rubbers for engine mounts and the like are required to have heat resistance and durability under severe conditions.

Under such severe conditions, conventionally used vulcanized rubber compositions using natural rubber alone or natural rubber and existing diene rubber as raw rubbers do not necessarily have sufficient heat resistance and durability. Never

Further, as disclosed in JP-A-61-225230, an anti-vibration rubber composition using a solution-polymerized polymer containing an amino group at a terminal, and a solution polymerization having a high vinyl bond disclosed in JP-A-61-225226. Even with a vibration-isolating rubber composition using a raw rubber composed of a polymer and a solution-polymerized polymer having a low vinyl bond as a natural rubber, the above heat resistance and durability were not always sufficient.

[Problems to be solved by the invention]

An object of the present invention is to provide an anti-vibration rubber composition having good strength, heat resistance and durability, sound and anti-vibration performance, etc., which cannot be solved by the above-mentioned conventional methods.

[Means for solving the problem]

Means for Solving the Problems The present inventors have conducted intensive studies on a polymer used for a rubber composition in order to solve the above problems, and as a result, have found that the object can be achieved by using a polymer having a specific structure, and have completed the present invention.

That is, the present invention provides an anti-vibration rubber composition having the following components (I), (II) and (III).

(I) Component: A raw rubber component comprising the following components (A) and (B) and having a total amount of 100 parts by weight.

(A) Component; (a) Mooney viscosity (ML _{1 + 4} , 100 ° C.) is 80 or more (b) Styrene content is 25 to 35% by weight (c) Butadiene moiety has a vinyl bond amount of microstructure
10 to 50% (d) A lithium-based catalyst in which a single styrene unit having one styrene unit is 50% by weight or more of the styrene content and a long chain of styrenes having eight or more styrene units is 0% by weight of the styrene content. Styrene polymerized by
20-80% by weight of butadiene random copolymer.

(Component B) 20 to 80% by weight of natural rubber or polyisoprene rubber having a cis bond amount of 90% or more.

Component (II): 25 to 100 parts by weight of reinforcing carbon black based on 100 parts by weight of component (I).

Component (III): 0.5 to 3.0 parts by weight of a vulcanizing agent per 100 parts by weight of component (I).

 Hereinafter, the present invention will be described in detail.

The raw rubber component of the rubber composition of the present invention comprises (A) a component,
It comprises a high molecular weight styrene-butadiene random copolymer rubber having a specific structure, component (B), and a natural rubber-based polymer.

The styrene-butadiene random copolymer rubber having a specific structure of the component (A) is a solution-polymerized styrene-butadiene copolymer rubber obtained by randomly copolymerizing styrene and butadiene with a lithium catalyst in a hydrocarbon solvent. is there.

Mooney viscosity of this rubbery polymer (ML _{1 + 4} , 100 ℃)
Is 80 or more, preferably in the range of 100 to 160. The Mooney viscosity of the rubber-like polymer is a measure of the molecular weight of the rubber, and the specific rubber used as the component (A) of the raw rubber in the present invention has been commonly used in anti-vibration rubber applications. It is characterized in that it has a higher Mooney viscosity than the rubbery polymer used, and thus has a high molecular weight.

When the Mooney viscosity of the rubbery polymer as the component (A) is less than 80, the mechanical strength and heat resistance are poor and the heat resistance is poor. As the Mooney viscosity increases, the general tendency is that the processability deteriorates, but a polymer having a high molecular weight is preferable as long as molding and processing can be performed. But,
If the molecular weight is too high and the Mooney viscosity is too high, the kneading of the polymer and the compounding agent cannot be performed sufficiently, the compounding agent disperses, etc., and the polymer inherently has poor performance. Therefore, the Mooney viscosity of the rubbery polymer is preferably about 160 or less.

The molecular weight of the rubbery polymer is 25 to 25 in weight average molecular weight.
The range of 600,000 is preferable, and the molecular weight distribution is such that Mw / Mn is 1.0.
A range of 5 to 3.0 is preferred.

As the rubber-like polymer, an oil-extended rubber in which 5 to 40 parts of a rubber-extending oil used as a component of the vibration-proof rubber composition for the purpose of improving the processability is added to the rubber-like polymer in advance. It is also possible to use it as a state polymer.

The styrene content of the rubbery polymer of the component (A) is 25 to 35.
% By weight. If the styrene content is less than 25% by weight, the mechanical strength is poor, and if it exceeds 35% by weight, the low-temperature performance is reduced. More preferably, the styrene content is in the range of 25-30%.

The vinyl bond content of the microstructure of the butadiene portion of the rubbery polymer as the component (A) is in the range of 10 to 50%.
If the vinyl bond amount is less than 10%, the compatibility with the natural rubber used as the component (B) is poor, while if the vinyl bond amount exceeds 50%, the mechanical strength and abrasion resistance are reduced. The vinyl bond amount is preferably in the range of 15 to 45%, particularly preferably in the range of 20 to 40%. The trans-1,4 bond amount, which is another microstructure of the butadiene portion, is preferably 30 to 55%, and the cis-1,4 bond amount is preferably 20 to 35%.

The microstructure of the butadiene portion of the styrene-butadiene copolymer rubber can be adjusted by adding a polar solvent such as an ether or an amine that increases the amount of vinyl bonds to the polymerization system in the synthesis of the polymer.

The rubbery polymer of the component (A) has a styrene single chain having one styrene unit of 50% by weight or more of the styrene content, and a styrene long chain of 8 or more styrene units having a styrene content of 0% by weight of the styrene content. is there. The styrene chain of such a styrene-butadiene copolymer is obtained by cleaving the double bond of the butadiene portion of the polymer with ozone, and separating the resulting component having styrene units into one to many styrene chains by GPC. Measure by doing.

When the styrene single chain having one styrene unit is less than 50% by weight of the styrene content, heat resistance and soundproofing properties are unfavorable, and a long styrene chain having eight or more styrene units connected is not 0% by weight of the styrene content. , Mechanical strength, heat resistance and heat resistance are inferior.

The amount of styrene units should be controlled by adjusting the supply rates of styrene and butadiene, adjusting the reaction rate, adjusting the polymerization temperature, adjusting the amount of polar solvent, and combining these to obtain a polymer with the target styrene units. Becomes possible.

In addition, the styrene unit of the styrene-butadiene copolymer of the present invention may be present uniformly in the molecular chain as long as it is within the above-mentioned chain-related limits, or the amount of styrene may be along the molecular chain. It may be a polymer that gradually increases or decreases, or a polymer in which a portion having a large amount of styrene and a portion having a small amount of styrene exist as a block.

Further, the styrene-butadiene copolymer rubber used as the component (A) of the present invention is a polymer having a branched structure, in addition to the above-mentioned limitations (a) to (d), which has sufficient performance. It is preferable to provide a rubber composition having excellent processability at the same time. Styrene having a branched structure
Butadiene copolymer rubber reacts, for example, a styrene-butadiene copolymer having a lithium active terminal synthesized by a general solution polymerization method with a polyfunctional coupling agent,
It is obtained by a method in which a part of the polymer is converted into a branched polymer. As the polyfunctional coupling agent, polyhalogen compounds, polyepoxy compounds, polyester compounds and the like are preferable. Examples of the polymer used as the component (A) in the present invention include tetrahalides such as silicon tetrachloride and tin tetrachloride; tetrafunctional ester compounds such as adipic acid; tetraglycidyl-1,3-bisaminomethylcyclohexane; A rubber-like polymer including a branched polymer coupled with a tetrafunctional compound represented by the following tetrafunctional epoxy compound is preferable.

The amount of the component (A) is 20 to 80% by weight of the raw rubber component. When the amount of the component (A) is less than 20% by weight, the heat resistance and durability are not sufficient. On the other hand, when the amount of the component (A) exceeds 80% by weight, there is a problem in processing method and moldability, which is not preferable.

The amount of the component (A) is preferably 30 to 70% by weight of the raw rubber component.

As one example of the component (A) of the present invention, copolymer rubbers described in Japanese Patent Application Laid-Open No. 61-255908, International Publication WO87 / 05610, etc., by the present applicant are used.

Next, the component (B) of the raw rubber component is a natural rubber or a polyisoprene rubber having a system binding amount of 90% or more. This raw rubber component is a component necessary for improving the strength, durability at room temperature, and heat resistance of the vibration-proof rubber composition of the present invention. As natural rubber, crumb rubber and sheet rubber produced in countries around the world are used. Polyisoprene rubber with a cis content of 90% or more is Zeigler-Natta
It is a synthetic rubber polymerized with a lithium catalyst or a lithium catalyst. The amount of the rubber of the component (B) is from 20 to 80 of the raw rubber.
% By weight. When the component (B) is less than 20% by weight, mechanical strength and heat resistance are not sufficient, and when it exceeds 80% by weight, heat resistance and durability are inferior. The amount of the component (B) is more preferably 30 to 70% by weight of the raw rubber.

Next, as the component (II) of the present invention, a reinforcing carbon black is added in an amount of 25 parts per 100 parts by weight of the raw material rubber of the component (I).
100100 parts by weight.

As the carbon black, ones such as ISAF, HAF, FEF, and SRF are selected and used according to the intended use of the anti-vibration rubber, and two or more carbon blacks can be used in combination.

The carbon black imparts strength, abrasion resistance, and the like to the vibration damping rubber composition, and adjusts the hardness and elastic modulus of the vibration damping rubber composition together with a rubber extending oil described later.

The amount of carbon black is 2 per 100 parts by weight of raw rubber.
If it is less than 5 parts, the mechanical strength and wear resistance are not sufficient,
On the other hand, if it exceeds 100 parts by weight, heat build-up and sound insulation performance deteriorate.

The amount of carbon black is 30 per 100 parts by weight of raw rubber
More preferred is a range of -80 parts by weight.

Furthermore, as fillers other than carbon black, inorganic fillers such as silica, calcium carbonate, talc, and clay,
A fibrous metal or resin can also be used.

Next, as a component (III) of the vibration damping rubber composition of the present invention, a vulcanizing agent is added to 100 parts by weight of the raw material rubber of the component (I).
Add 0.5 to 3.0 parts by weight.

As the vulcanizing agent, sulfur is a typical and preferred one, and in addition, sulfur-containing compounds such as tetramethylthiuram disulfide and morpholine disulfide, oximes, and peroxides are used.

Further, in the rubber composition of the present invention, an extender oil for rubber, a chemical for rubber, and an additive for rubber are blended as required. Rubber extender oil is used to improve the processability of the compound and further adjust the hardness and elastic modulus of the compound. Aromatic, naphthenic and paraffinic rubber extender oils are typically preferred. It is. Aromatic extender oils have good strength and anti-vibration performance, and naphthene and paraffin-based oils are effective in improving low-temperature performance and soundproof performance. The use amount of these extender oils is about 0 to 50 parts by weight per 100 parts by weight of the raw rubber.

In order to make the composition of the present invention a vibration-proof rubber composition having good soundproofing performance, as long as the processability, hardness, elastic modulus, and mechanical strength of the rubber composition are within a target range, the carbon black is hardened. Preferably, the amount and extensibility are small.
Therefore, in order to improve the soundproofing performance, the extensibility is preferably in the range of about 0 to 20 parts by weight based on 100 parts by weight of the raw rubber.

As rubber chemicals and rubber additives, vulcanization accelerators such as zinc white and stearic acid, sulfenamides, thiurams, thiazoles, vulcanization accelerators such as guanidines, amines, phenols, Sulfur-based or phosphorus-based antioxidants or antioxidants, ultraviolet absorbers, antiozonants, tackifiers, plasticizers, and the like are used according to the purpose of use of each vibration-proof rubber composition.

The hardness of the anti-vibration rubber composition of the present invention is determined by using a vulcanized rubber composition having a JIS-A hardness in the range of 45 to 80 according to the intended use, and the hardness depends on the type and amount of the carbon black to be compounded. , The type and amount of extender oil and the type and amount of vulcanizing agent and vulcanization accelerator.

The anti-vibration rubber composition of the present invention is obtained by compounding and kneading the above components with a rubber kneading roll, an internal mixer, an extruder or other rubber mixing device, and then assembling with metal fittings and the like by a conventional method. Vulcanized under pressure at a temperature of 130-200 ° C. and ready for use.

〔Example〕

Hereinafter, the characteristics of the composition of the present invention will be described in more detail with reference to Examples.

(Raw material of the present invention used in Examples)

A styrene-butadiene random copolymer used as a raw material rubber of the component (A) in the present invention was synthesized by the following production method.

A stainless steel stirrer with an internal volume of 10 liters and two reactors with a jacket were connected in series.
-Butadiene and styrene (75/25 weight ratio), n-hexane as a solvent and n-butyllithium as a monomer
0.050 g per 100 g (phm), 0.60 phm of ethylene glycol dibutyl ether as a vinylating agent, and 1,2-butadiene as an allene compound at 0.02 g / mol of catalyst.
Continuous polymerization was carried out using moles. In the first reactor, the internal temperature was controlled so as to be 100 ° C., and the above monomers, solvents and the like were supplied by a metering pump so that the average residence time was 45 minutes. The polymerization rate of the first outlet was measured by gas chromatography, and a butadiene conversion rate of 97% and a styrene conversion rate of 94% were obtained. Mooney viscosity (ML _{1 + 4} , 100
C) was 70.

Further, the polymer solution discharged from the first reactor was continuously introduced into the second reactor. In the second reactor, 0.029 phm of silicon tetrachloride was continuously added as a coupling agent, and the internal temperature was lowered to 100 ° C.
° C. The polymerization reaction and the coupling reaction were carried out by the above methods to obtain a styrene-butadiene random copolymer sample A-1 used in the present invention. The polymerization rate of the second outlet was measured by gas chromatography to obtain a conversion rate of butadiene of 99.3% and a conversion rate of styrene of 98.0%. The Mooney viscosity of the resulting polymer after coupling is
It was 128.

In addition, the infrared absorption spectrum was measured using an infrared spectrophotometer, and the styrene content and the microstructure of the butadiene portion (cis, trans, vinyl) were determined by the Hampton method.
Styrene content is 25%, cis bond content is 28%,
The trans binding amount was 39% and the vinyl binding amount was 33%.

The analysis of styrene chain distribution is a method developed by Tanaka et al. Specifically, a decomposition product obtained by ozone cleavage of all double bonds of a butadiene unit is subjected to gel permeation chromatography (GPC). This is a method for fractionation and quantification. (POLYMER, 1981, Vol 22, 1721). As a result of analyzing the styrene chain of A-1 according to this method, the amount of a styrene single chain having one styrene was found to be 72% by weight of the styrene content and a styrene long chain having eight or more styrene chains. The amount was zero.

The GPC of Sample A-1 was measured, and the weight average molecular weight (Mw) calculated using a calibration curve using standard polystyrene and standard polybutadiene was 324,000, the number average molecular weight (Mn) was 138,000, and the molecular weight distribution ( (Mw / Mn) was 2.34, and the shape of the GPC curve was a gentle single-peak shape.

The obtained polymer solution contained 2,6-
Di-tert-butyl-p-cresol was added, 20 phr of a naphthenic extender oil was added, the solvent was removed by steam stripping, and the mixture was dried with a hot roll. Of oil-extended polymer,
The Mooney viscosity was 72.

Further, the polymerization conditions (ratio of styrene and butadiene, amount of catalyst, type and amount of vinylating agent, type and amount of coupling agent, polymerization temperature, etc.) were changed in the same manner as in obtaining sample A-1. Thus, samples A-1 to A-11 shown in Table 1 were obtained.

In addition, commercially available styrene-
A butadiene random copolymer rubber was prepared.

Further, RSS1 (sample B-1) was used as a natural rubber used as the component (B) of the raw rubber of the present invention.

[Adjustment and Measurement of Rubber Composition] In the present invention, the rubber compound was prepared according to the evaluation formula shown in Table 3 using a test Banbury mixer having a content of 1.71 and a 10-inch mixing roll for test using ASTM-D-34.
Kneading was performed according to the mixing procedure of Method B of the standard mixing procedure shown in 03-75, molded into a predetermined shape, and then heated at 145 ° C. for 35 minutes to obtain a rubber composition sample, and various physical properties were measured. The measurement was performed according to the following method.

(1) Roll processability: Comprehensively determined by the wound state of the compound on a roll in a 10-inch roll mill, the edge of the dispensing sheet and the surface skin. The higher the number, the better.

(2) Hardness and tensile test: Measured according to JIS-K-6301.

(3) Dynamic magnification and loss factor, JIS-K-6385 and J
Measured according to IS-K-6394. Using an anti-vibration rubber vibration tester, loss factor (tan δ) at 15Hz amplitude 1%, 100Hz, amplitude 0.
Measure dynamic modulus (Kd) at 1%. The ratio between the dynamic elastic modulus and the static elastic modulus (Ks) was defined as the dynamic magnification.

The smaller the dynamic magnification is a measure of soundproofing performance, the better the soundproofing performance. The larger the value of the loss coefficient (tan δ) is, the better the vibration isolation performance is.

(4) Compression set: 100 ° C, 2 according to JIS-K-6301
Measure the strain after 2 hours.

Compression set is a measure of static heat and durability, and the smaller the strain, the better.

(5) Heat resistance / durability test: Measure the strain after 100,000 repetitions of compression with a stroke of 5.71 mm and 100,000 times (reduction in the height of the original sample (%)) using a heat generating test machine.
The smaller the distortion, the better.

(6) Low temperature hardness: Hardness (JIS-A) is measured in a constant temperature bath at -20 ° C.

Table 3 Formulation for evaluation-1 Raw material rubber (total) 100 parts Extending oil ^{* 1} 15 parts N550 carbon black ^{* 2} 40 parts Zinc white flower 5 parts Stearic acid 2 parts Antioxidant 810NA ^{* 3} 1.5 parts Iow 1.5 parts Sulfur Accelerator NS ^{* 4} 1.0 part Vulcanization Accelerator TT ^{* 5} 0.2 part * 1 Kyodo Sekiyu naphthenic oil R-1000 * 2 Tokai Carbon brand Seast SO * 3 N-isopropyl-N'-phenyl-p-phen Nilendiamine * 4 N-tet-butyl-2-benzothiazyl sulfenamide * 5 Tetramethylthiuram disulphide Example 1-1, Comparative Examples 1-1 to 1-13 Table 3 shows the composition of the raw rubber shown in Table 4. Evaluation Formulation-1
Was prepared and vulcanized at 160 ° C. for 20 minutes to prepare a test piece, which was subjected to a predetermined test. Table 4 shows the results. From the results shown in Table 4, as the component (A) of the raw rubber, the anti-vibration rubber composition of Example 1-1 using the rubber of the styrene-butadiene random copolymer limited by the present invention has excellent processability, Comparative Examples 1-1 to 1-1 using a rubbery polymer outside the scope of the present invention as the component (A) of the raw rubber, while having tensile strength and anti-vibration rubber performance.
13 anti-vibration rubber composition, processability, tensile strength, sound insulation performance,
One or more of compression set and low-temperature hardness are inferior.

Examples 2-1 to 2-6 and Comparative examples 2-1 to 2-2 As shown in Table 7, the samples A-1 and B-1 were used as raw rubber components, and the types of carbon black and extender oil were used. The amount was changed, the other compounding agents were as shown in Table 5, the rubber composition was adjusted in the same manner as in Example 1, and a predetermined test was performed. Table 6 shows the results.

As is clear from the results in Table 6, Example 2 in which the carbon black of the component (II) of the present invention is within the limits of the present invention.
The compositions 1 to 2-6 have a good balance of the vibration-proof rubber performance, whereas the rubber compositions of Comparative Examples in which the amount of the carbon black is out of the range of the present invention are inferior in the vibration-proof rubber performance. .

Table 5 Formulation for evaluation-2 Raw material rubber (total) 100 parts Extending oil ^{* 1} variable part N550 carbon black ^{* 2} variable part Zinc flower 5 parts Stearic acid 2 parts Antioxidant 810NA ^{* 3} 1.5 parts Iow 1.6 parts Sulfur Accelerator NS ^{* 4} 1.1 parts Vulcanization Accelerator TT ^{* 5} 0.2 parts * 1 Kyodo Sekiyu naphthenic oil R-1000 * 2 Tokai Carbon trade name Seast SO * 3 N-isopropyl-N'-phenyl-p-phenyl Nilendiamine * 4 N-tet-butyl-2-benzothiazyl sulfenamide * 5 Tetramethylthiuram disulfide [Effects of the Invention] As is clear from the above, the anti-vibration rubber composition comprising the styrene-butadiene random copolymer rubber and the natural rubber-based polymer of the present invention has processability, strength, durability against sound emission, soundproofing performance and the like. The rubber is suitable for use in various parts of automobiles such as passenger cars, trucks, buses, construction vehicles, light trucks, railway vehicles, etc. by taking advantage of these characteristics. A composition. Further, by utilizing the above characteristics, the rubber composition can be used for automobile parts such as belts and belt conveyors and various industrial supplies, and is a useful rubber composition in many fields.

Continued on the front page (51) Int.Cl. ⁶ Identification code Reference number in the agency FI Technical display location C08L 9:00)

Claims (1)

(57) [Claims] An anti-vibration rubber composition having the following components (I), (II) and (III). (I) component; a raw rubber component comprising the following (A) component and (B) component;
100 parts by weight (A) component; (a) Mooney viscosity (ML _{1 + 4} , 100 ° C.) is 80 or more (b) Styrene content is 25 to 35% by weight (c) Butadiene moiety has a vinyl bond amount of microstructure Ten
(D) a lithium-based catalyst in which a single styrene unit having one styrene unit has a styrene content of 50% by weight or more and a styrene long chain having eight or more styrene units has a styrene content of 0% by weight. Polymerized styrene
Butadiene random copolymer 20 to 80% by weight (B) component; natural rubber or 20 to 80% by weight of polyisoprene rubber having a cis bond amount of 90% or more (II) component; reinforcing carbon black, 25 to 100 parts by weight (III) ) Ingredient; vulcanizing agent, 0.5 to 3.0 parts by weight.