JPH08269236A - Vibration-proofing rubber composition - Google Patents

Abstract

PURPOSE: To obtain a vibration-proofing rubber composition improved in heat resistance, durability and creep resistance by a specified rubber composition with thiocyanatopropyl-trialkoxysilane. CONSTITUTION: This composition is prepared by mixing 100 pts.wt. composition prepared by mixing 100 pts.wt. composition prepared by mixing a natural rubber with 10-50wt.% carbon black of a mean particle diameter of 40-130nm or composition prepared by mixing 50-90wt.% rubber component comprising a natural rubber and a styrene/butadiene rubber or a butadiene rubber with 10-50wt.% carbon black of a mean particle diameter of 40-130nm with 1-8 pts.wt. thiocyanatopropyltrialkoxysilane.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant anti-vibration rubber composition, and more particularly to an anti-vibration rubber composition and anti-vibration rubber composition suitable for automobile engine mounts.

[0002]

2. Description of the Related Art Anti-vibration rubber used when mounting an automobile engine, etc., has anti-vibration properties to reduce engine vibration and accompanying noise, as well as heat resistance to heat generated by the engine. In addition, supporting performance (strength) for mechanically supporting the engine is required. From the standpoint of anti-vibration performance, rubber is generally suitable as soft as it is, but if it is too soft, it will bend due to the weight of the load and its support position will change, adversely affecting the basic performance of the entire structure including the support. Will affect. Specifically, the smaller the spring constant (dynamic spring constant) of the vibration state for transmitting vibration is, the better the vibration isolation performance is, and the larger the static spring constant indicating the support rigidity is, the better the support performance (strength) is. It can be said that a rubber having a smaller ratio of the dynamic spring constant to the static spring constant, that is, the value of the dynamic magnification (dynamic spring constant / static spring constant) is superior as a vibration isolating rubber.

As such a vibration-proof rubber, at present, natural rubber (NR) excellent in vibration-proof property, and natural rubber and styrene-butadiene rubber (SBR) or butadiene rubber (BR) are used.
A rubber composition is used in which a blended rubber of and is used as a base (matrix) and carbon black as a reinforcing material is mixed therein. However, these rubber compositions basically have poor heat resistance because they have a double bond in the main chain of the rubber polymer, and the physical properties deteriorate when used for a long time in a high temperature environment such as an automobile engine room. Has a problem of significant thermal deterioration and dynamic fatigue. In particular, if the engine mount on which the engine is mounted deteriorates over time and its shape changes, the supporting position of the engine changes, which not only deteriorates the vibration characteristics, but also causes interference with the engine and its surrounding parts, which may cause damage. There is.

A change in shape of a rubber such as an engine mount, which is required to have heat resistance, with time, is a change amount (that is, creep) when the rubber is held at a high temperature for a certain time under a constant load (see below). Can be evaluated by measuring the test method in the example), but this creep is a compression set (so-called "fatigue"), which is measured by releasing the load and returning to normal temperature; However, even if the compression set is excellent, the creep property is often ineffective. As a vibration-proof rubber composition for engine mounts, one having good creep characteristics is desired. In addition, since the vulcanized rubber has a low binding energy at the cross-linking point and is easily decomposed by heat, the amount of the sulfur component used as the cross-linking agent may be reduced for the purpose of improving the heat resistance of the anti-vibration rubber composition based on natural rubber. Or, a method of using a non-sulfur crosslinking agent is adopted, but since the crosslinking density is generally small,
Since the target rubber hardness cannot be obtained, it is necessary to add a large amount of reinforcing material such as carbon black.
However, when the amount of the reinforcing material increases, the dynamic ratio increases due to the interaction between the rubber polymer and the reinforcing material, and the vibration characteristics deteriorate. In addition, low sulfur or non-sulfur cross-linking agent system,
Vulcanization accelerator and certain vulcanizing agents (sulfur-containing organic compounds, etc.)
Although it is possible to increase the crosslink density by adding, the fatigue resistance is deteriorated.

Therefore, an object of the present invention is to provide an anti-vibration rubber composition in which NR excellent in anti-vibration property and a blended rubber of NR and SBR or BR with carbon black as a reinforcing material are combined, and heat resistance and durability are improved. To improve. Further, another object of the present invention is to provide a vibration-proof rubber composition which is excellent in heat resistance and creep characteristics and which is suitable for engine mounts.

[0006]

[Means for Solving the Problems] The cause of the thermal creep phenomenon of a rubber composition is (1) cutting of polymer molecules by heat, (2) cutting of crosslinking points by heat, (3) rubber polymer and carbon by heat It is conceivable that the secondary bond of black is broken and the shift phenomenon accompanied by it is considered. However, the present inventor has found that the carbon black content of carbon black can be increased without increasing the compounding amount of carbon black, which adversely affects the vibration damping characteristics (dynamic magnification). As a result of extensive studies on the combined use of additives which may improve thermal creep characteristics by interacting (reacting) with surface functional groups, the following formula

[0007]

Embedded image (R ¹ O) (R ² O) (R ³ O) SiCH ₂ CH ₂
Thermal creep and low vibration by using a thiocyanate propyltrialkoxysilane represented by CH ₂ SCN (wherein R ¹ , R ² and R ³ represent alkyl groups which may be the same or different) The inventors have found that the transferability is improved and completed the present invention.

That is, the present invention is: 1) A composition in which carbon black is mixed with natural rubber,
Alternatively, a vibration-insulating rubber composition obtained by kneading a composition in which carbon black is mixed with a blend rubber of natural rubber and styrene-butadiene rubber or butadiene rubber, and kneading with thiocyanatepropyltrialkoxysilane, 2) natural rubber or natural rubber and styrene A vibration-proof rubber composition obtained by kneading 1 to 8 parts by weight of thiocyanatepropyltrialkoxysilane with respect to 100 parts by weight of butadiene rubber or a blended rubber with butadiene rubber, 3) thiocyanatepropyltrialkoxysilane is thiocyanatepropyltriethoxy The vibration-insulating rubber composition as described in 1 or 2 above, which is silane. 4) The average particle size of carbon black is 40 to 130 n.
m) The antivibration rubber composition according to any one of 1 to 3 above, 5) a natural rubber, or a blending ratio of natural rubber and a blend rubber of styrene-butadiene rubber or butadiene rubber and carbon black, The antivibration rubber composition according to any one of 1 to 4 above, wherein the rubber component is 50 to 90% by weight and the carbon black is 10 to 50% by weight. 6) Any one of the above 1 to 5 for engine mount Item 7. A vibration-proof rubber composition, which is obtained by using the vibration-proof rubber composition according to any one of items 1 to 6 above. Hereinafter, the anti-vibration rubber composition and anti-vibration rubber of the present invention will be described in detail.

[0009]

[Rubber Polymer] In the present invention, as the rubber polymer matrix (base), natural rubber or natural rubber and styrene-butadiene rubber (SBR) or butadiene rubber (B) is used.
Use a rubber blend with R). Natural rubber has good processability and mechanical strength characteristics (durability), and can be effectively used as a rubber polymer matrix in a wide range in the present invention. When a blended rubber is used as the matrix, a blended rubber of natural rubber and SBR or BR is used. SBR is effective in improving heat resistance, and BR is effective in reducing dynamic magnification.

[0010]

[Carbon Black] In the anti-vibration rubber composition of the present invention, it is important to use carbon black and thiocyanatepropyltrialkoxysilane in the above rubber polymer matrix. The carbon black used in the present invention as a reinforcing material for increasing the supporting strength of the anti-vibration rubber composition has an appropriate functional group that reacts with thiocyanatepropyltrialkoxysilane when compounded in the rubber matrix. The smaller the average particle size of carbon black, the greater the reactivity with thiocyanate propyltrialkoxysilane. However, if the average particle size is too small, the dynamic magnification, which is an index of vibration transmissivity, increases. Therefore, the average particle size is preferably 40 nm or more. On the other hand, if the particle size is too large, the surface functional groups are remarkably reduced and the effect of adding thiocyanatepropyltrialkoxysilane decreases, so the average particle size is preferably less than 130 nm. The blending amount of carbon black cannot be unconditionally specified because it depends on the use of the anti-vibration rubber, but generally 10 to 50% by weight is preferable.

[0011]

[Thiocyanate propyltrialkoxysilane] The present inventor plays a role of an organic resin and an inorganic substance,
The addition of a silane coupling agent, which is known to have effects such as improvement of physical strength, improvement of affinity of inorganic substance to organic resin and adhesion, and suppression of reduction of physical strength under high temperature and high humidity, was examined. As a result, for example, mercaptopropyltrimethoxysilane, which is generally used in the field of rubber, has some effect, but it cannot be blended in a large amount due to the scorch (rubber burning) phenomenon.
Almost no effect is observed with a small amount of compound that does not cause scorch. On the other hand, among the silane coupling agents, thiocyanatepropyltrialkoxysilane:

Embedded image (R ¹ O) (R ² O) (R ³ O) SiCH ₂ CH ₂
It was confirmed that CH ₂ SCN (in the formula, R ¹ , R ² and R ³ represent an alkyl group which may be the same or different) has an excellent effect. In particular, thiocyanatepropyltriethoxysilane in which all of R ¹ , R ² and R ³ are ethoxy groups shows a particularly excellent effect. The compounding amount of thiocyanate propyltrialkoxysilane is 100 parts by weight of the rubber component (natural rubber or blend rubber of natural rubber and styrene-butadiene rubber or butadiene rubber).
It is 1 to 8 parts by weight with respect to parts by weight. If it is less than 1 part by weight, it cannot react sufficiently with the blended carbon black, so that there is no effect, and if it exceeds 8 parts by weight, scorch occurs.

Further, a processing aid, an antioxidant, a vulcanizing agent, a vulcanization accelerator, a softening agent, a filler and the like may be added to the antivibration rubber composition of the present invention. As the vulcanizing agent, any commonly used vulcanizing agent can be used. Examples of such compounds include sulfur, morpholine disulfide, tetramethylthiuram disulfide and the like. Of these, sulfur is preferred, and is 0.5 to 5 per 100 parts by weight of the rubber component.
About parts by weight can be used.

The vulcanization accelerator is an additive for suppressing radical cleavage of the rubber polymer and improving the crosslinking effect, and can be used in an amount of about 0.5 to 5 parts by weight per 100 parts by weight of the rubber component. Examples of the vulcanization accelerator include sulfites such as N-cyclohexyl-2-benzothiazole sulfenamide, N-oxydiethylene-2-benzothiazole sulfenamide, and N, N-diisopropyl-2-benzothiazole sulfenamide. Phenamide compounds; 2-mercaptobenzothiazole, 2- (2,4-dinitrophenyl) mercaptobenzothiazole, 2- (2,6-
Thiazole-based compounds such as diethyl-4-morpholinothio) benzothiazole and dibenzothiazyl disulfide;
Guanidine compounds such as diphenylguanidine, dioltotolylguanidine, triphenylguanidine, orthotolylbiguanide, diphenylguanidine phthalate;
Acetaldehyde-aniline reaction products, butyraldehyde-aniline condensates, hexamethylenetetramine, acetaldehyde-ammonia reaction products and other aldehyde-amines or aldehyde-ammonia compounds; 2-mercaptoimidazoline and other imidazoline compounds; thiacarbamide, diethylthiourea, Thiourea compounds such as dibutylthiourea, trimethylthiourea and diortotolylthiourea; thiuram compounds such as tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, pentamethylenethiuram tetrasulfide; dimethyl Zinc dithiocarbamate, zinc diethyldithiocarbamate, zinc dibutylthiocarbamate, ethylphenyldithio Rubamin zinc, butylphenyl dithiocarbamate, zinc, sodium dimethyl dithiocarbamate, dimethyl dithiocarbamate selenium dithiocarbamate compound tellurium diethyldithiocarbamate and the like; Compound of xanthate-based compounds such as dibutyltin xanthate acid zinc.

The softening agent is used up to about 100 parts by weight with respect to 100 parts by weight of the above rubber component. Examples of softening agents include petroleum-based softening agents such as procell oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt, and vaseline; fatty oil-based softening agents such as castor oil, linseed oil, rapeseed oil, and coconut oil; tall oil. Waxes such as sub; beeswax, carnauba wax, lanolin; linoleic acid, palmitic acid, stearic acid, lauric acid, etc., and process oil is particularly preferably used. Examples of fillers other than carbon black include calcium carbonate, talc, silica and the like. In addition to the above additives, plasticizers, stabilizers,
Conventional compounding agents such as processing aids and colorants may be used.

[0015]

[Production Method] The anti-vibration rubber composition of the present invention can be produced by a conventional method using the above rubber component, carbon black, thiocyanatepropyltrialkoxysilane and other additives.

The anti-vibration rubber of the present invention described above is a natural rubber (N
R), and natural rubber and styrene-butadiene rubber (SB
R) or butadiene rubber (BR) blended rubber with a composition of carbon black as a reinforcing material,
It contains a small amount of thiocyanate propyltrialkoxy silane, and has excellent heat resistance and durability, especially creep characteristics. It can be used for engine mounts as well as body mounts, cab mounts, member mounts, strut bar cushions, center bearing supports, and torsional dampers. , Steering rubber couplings, tension rod bushes, suspension bushes, strut mounts, FF engine roll stoppers, muffler hangers, and other various vibration-proof rubber components for automobiles, and are particularly suitable for engine mounts.

[0017]

The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following description. In each of the examples and comparative examples, the following materials were used as raw materials and additives.

(1) Rubber component Natural rubber: RSS # 3. (2) Carbon black (i) Average particle size 43 nm; # 6 manufactured by Asahi Carbon Co., Ltd.
0, (ii) average particle diameter 120 nm; Asahi Carbon Co., Ltd. # 15, (iii) average particle diameter 28 nm; Asahi Carbon Co., Ltd. # 70. (3) Silane coupling agent (i) Thiocyanatepropyltriethoxysilane (manufactured by Degussa), (ii) Mercaptopropyltrimethoxysilane (manufactured by Nippon Unicar Co., Ltd.).

(4) Vulcanizing agent Sulfur. (5) Vulcanization accelerator (i) CZ: N-cyclohexyl-2-benzobenzothiazolylsulfenamide (manufactured by Ouchi Shinko Chemical Co., Ltd.),
(ii) TT: tetramethylthiuram disulfide (manufactured by Ouchi Shinko Chemical Co., Ltd.), (iii) zinc white (ZnO). (6) Softener (i) naphthenic process oil, (iii) stearic acid. (7) Anti-aging agent Amine anti-aging agent: N- (1,3-dimethylbutyl)
-N'-phenyl-p-phenylenediamine (manufactured by Ouchi Shinko Chemical Co., Ltd.).

Examples 1 to 4 and Comparative Examples 1 to 5 The above components were blended in the proportions shown in Table 1 by a conventional method and kneaded to prepare rubber compositions.

[0021]

[Table 1] Blending example of rubber composition Natural rubber 100 parts by weight Zinc white 5 parts by weight Stearic acid 1 part by weight Anti-aging agent 1 part by weight Silane coupling agent Variable (see Table 2) Carbon black 〃 Process oil 5 parts by weight CZ 1 part by weight TT 0.5 parts by weight Sulfur 1 parts by weight

The obtained rubber composition was molded as described below,
The test piece was cross-linked and the scorch time, creep test, dynamic ratio, compression set, and normal state characteristics (strength, tensile strength, elongation at break) were measured by the following methods. The results are also shown in Table 2.

1) Scorch time The scorch time means the time required to increase the viscosity by 5 units in Mooney units from the minimum viscosity by measuring the viscosity using a Mooney plastometer. The specific operation is the Mooney Scorch test specified in JIS K6300 (test temperature: 121
C)).

2) Creep test diameter 5 crosslinked by heating at 150 ° C. for 30 minutes
A cylindrical rubber test piece having a height of 0 mm and a height of 50 mm is prepared, and as shown in FIG. 1, the test piece 1 is sandwiched between disc-shaped metal fittings 2 and 3. Two such test pieces were prepared, and as shown in FIG. 2, the lower surfaces of the test pieces were mounted on the slopes of the bracket-shaped jig 4, and the jig 5 having a triangular vertical section was mounted on the upper surface. The angle Θ in the figure was 30 °. In this state, the jig 5
The upper surface 6 was kept horizontal, a load P of 200 kg was applied, and the distance a from the horizontal surface 7 of the lower jig was measured. Next, this is maintained in a constant temperature bath (120 ° C.) for 72 hours, and the distance a ′ between the upper surface 6 of the upper jig and the horizontal surface 7 of the lower jig is measured again with heating and load applied. Creep amount (a-
a ') was calculated.

3) Dynamic Magnification A cylindrical test piece having a diameter of 50 mm and a height of 25 mm was prepared by heating the compounded rubber composition at 150 ° C. for 30 minutes, and the upper surface and the lower surface thereof had a diameter of 60 mm and a thickness of 6 mm. Each of the circular metal fittings was attached, the static spring constant (Ks) and the dynamic spring constant (Kd100) were measured, and the dynamic magnification (Kd100 / Ks) was obtained. The static spring constant is 1.5 mm and 3.5 mm from the second load deflection curve obtained by compressing the cylindrical test piece in the axial direction of the cylinder by 7 mm in the axial direction.
The load at the time of bending was read and calculated. The dynamic spring constant is that the test piece is compressed 2.5 mm in the axial direction, and the amplitude is ± 0.
A constant displacement harmonic vibration of 05 mm was applied, the dynamic load was measured with a load cell mounted above the test piece, and calculation was performed according to JIS K6394. Dynamic magnification is the ratio of these values.

4) Compression set A load was applied to the crosslinked test piece by heating the compounded rubber composition at 150 ° C. for 20 minutes and maintained at 100 ° C. for 22 hours, after which the load was removed and returned to room temperature before deformation. The amount (compression set) was measured. The size and shape of the test piece and the magnitude of the load were in accordance with JIS K6301.

5) Normal State Properties A compounded rubber composition was molded, heated at 150 ° C. for 20 minutes and crosslinked to obtain a dumbbell type test piece (JIS K6301). Using this test piece, the measuring temperature is 25 according to the method described in JIS K6301.
Tensile test was carried out under conditions of ℃ and tensile speed of 500 mm / min., 100% modulus (M100), tensile strength (T
B) (MPa) and elongation at break (EB) (%) were measured. As for hardness (HS), the spring hardness was also measured with a JIS A hardness meter according to the method described in JIS K6301.

[0028]

[Table 2]

As shown in Table 2, in the examples in which thiocyanate ethoxysilane was added according to the present invention, the creep was in the range of 2 mm or less and the dynamic magnification was 1.3 or less.
It is suppressed to a low value such as double or less. On the other hand, when the silane coupling agent is not used (Comparative Example 1), and when the mercapto-based silane coupling agent is used (Comparative Examples 2 to 3), creep does not occur.
It exceeds 3.5 mm. It should be noted that the conventional engine mount causes a creep phenomenon of about 5 mm after traveling 100,000 kilometers. The improvement of creep effect exponentially affects the life of the mount.
It is a big effect that doubles. Further, it can be seen that when the addition amount of the mercapto-based silane coupling agent is large, the scorch time is extremely reduced and scorch is easily generated (Comparative Example 3). However, in the present invention, a particularly large amount of thiocyanate ethoxysilane silane is not used. As far as it is (Comparative Example 5), it does not cause significant scorch. Furthermore, it can be seen that the carbon black particles can be used in a wide range except for those having a particularly small particle size (Comparative Example 4).

[0030]

The anti-vibration rubber composition of the present invention has excellent thermal creep characteristics, and can be used at high temperatures (1
Deformation can be kept to a minimum even under a high load environment. Moreover, it is highly vibration-proof. Therefore, in actual use, the engine or the like can be stably supported with high accuracy over a long period of time. Further, the anti-vibration rubber composition of the present invention can be used at a low cost because it can be used as a natural rubber base, and its properties can be adjusted according to the object of application by blending with SBR or BR. Furthermore, since the scorch time is long, there is little risk of scorch.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing the shape of a creep test specimen.

FIG. 2 is a schematic cross-sectional view showing a state of a load applied to the test body during a test.

[Explanation of symbols]

 1 Test piece 2,3 Metal fittings 4,5 Jig

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[Procedure amendment]

[Submission date] September 20, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

[0021]

[Table 1] Blending example of rubber composition Natural rubber 100 parts by weight Zinc white 5 parts by weight Stearic acid 1 part by weight Anti-aging agent 1 part by weight Silane coupling agent Variable (see Table 2) Carbon black 〃 Process oil 5 parts by weight CZ 1 part by weight TT 0.5 parts by weight Sulfur 1 parts by weight

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Claims (7)

[Claims] 1. A thiocyanatepropyltrialkoxysilane is added and kneaded to a composition in which carbon black is mixed with natural rubber, or a composition in which carbon black is mixed with a blend rubber of natural rubber and styrene-butadiene rubber or butadiene rubber. Anti-vibration rubber composition. 2. An anti-vibration rubber composition obtained by adding and kneading 1 to 8 parts by weight of thiocyanatepropyltrialkoxysilane to 100 parts by weight of natural rubber or a blended rubber of natural rubber and styrene-butadiene rubber or butadiene rubber. 3. The antivibration rubber composition according to claim 1, wherein the thiocyanatepropyltrialkoxysilane is thiocyanatepropyltriethoxysilane. 4. The average particle size of carbon black is from 40 to 40.
The anti-vibration rubber composition according to claim 1, which has a thickness of 130 nm. 5. Natural rubber or natural rubber and styrene
The compounding ratio of butadiene rubber or a blended rubber with butadiene rubber and carbon black is 50 to 50% by weight.
The anti-vibration rubber composition according to any one of claims 1 to 4, which is 90% by weight and 10 to 50% by weight of carbon black. 6. The anti-vibration rubber composition according to claim 1, which is for engine mounts. 7. An anti-vibration rubber comprising the anti-vibration rubber composition according to claim 1.