JPH0583102B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a low-hardness anti-vibration rubber composition, and particularly to a anti-vibration rubber composition that has improved temperature characteristics and exhibits a stable anti-vibration effect over a wide temperature range. be. [Prior Art] Conventionally, anti-vibration rubber compositions made of polymeric substances with good anti-vibration properties, such as natural rubber and butyl rubber, have been used, but these materials deteriorate depending on the temperature. The drawback is that it can only be used within a very limited temperature range because its vibration-proofing effect changes significantly. In addition, by blending silicone rubber, which has almost no vibration-proofing effect but is known for its physical properties with small temperature dependence, with butyl rubber, which has good vibration-proofing properties, it exhibits a stable vibration-proofing effect against temperature changes. Attempts have also been made to create anti-vibration rubber. [Problems to be solved by the invention] However, the anti-vibration rubber made of silicone rubber and butyl rubber still has a fairly large temperature dependence in its anti-vibration effect, and it is difficult to obtain a stable anti-vibration effect over a wide temperature range. The current situation is that no rubber composition has been obtained. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a vibration-proof rubber composition whose vibration-proofing effect has little temperature dependence and which can provide a stable vibration-proofing effect over a wide range of temperatures. [Means for Solving the Problems] The present invention provides the following rubber composition as a solution to the above problems. That is, the present invention provides (A) average compositional formula ():

[Formula] [wherein R is a substituted or unsubstituted monovalent hydrocarbon group, and at least 50% of R is a methyl group; a is a number from 1.99 to 2.02] 100 parts by weight of siloxane, (B) 10~ fine silica powder with a specific surface area of 50 m ² /g or more
100 parts by weight, (C) General formula ();

3 parts by weight or more of an organopolysiloxane represented by the following formula: (where n is a number from 2 to 20), and (D) phenyl-β-naphthylamine, 4,4'-bis(α,α-dimethylbenzyl) Diphenylamine, N,N'-diphenyl-p-phenylenediamine, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, 2,6-di-t-butyl-4-methylphenol, 2 ，
2'-methylene-bis-(4-ethyl-6-t-
butylphenol), 4,4'-thiobis-(6-
t-butyl-3-methylphenol) and 2
- 0.01 to 10 parts by weight of at least one compound selected from the group consisting of mercaptobenzimidazole. is the main ingredient constituting the anti-vibration rubber composition of the present invention.
In the general formula () representing the organopolysiloxane of component (A), the substituted or unsubstituted monovalent hydrocarbon group represented by R is, for example, a methyl group,
Alkyl groups such as ethyl and propyl groups, alkenyl groups such as vinyl and allyl groups, phenyl groups,
Examples include aryl groups such as tolyl groups, and hydrocarbon groups in which part or all of the hydrogen atoms bonded to carbon atoms of these groups are substituted with one or more types such as halogen atoms, cyano groups, and mercapto groups. Specific examples include 3,3,3-trifluoropropyl group, cyanopropyl group, and mercaptopropyl group. Among these substituted or unsubstituted monovalent hydrocarbon groups, preferred are:
Examples include methyl group, vinyl group, and phenyl group. In the component (A) used in the present invention, further:
At least 50% of all R's contained in the molecule must be methyl groups, and preferably 75% or more are methyl groups. If methyl groups account for less than 50% of all R, the anti-vibration effect at low temperatures will be markedly reduced, the temperature dependence of the physical properties of the polymer will become large, and the heat resistance will also be poor. In addition, in the general formula (), a is 1.99 to 2.02, the organopolysiloxane of component (A) is substantially a linear polymer, and the average degree of polymerization is 5000 to 2.02.
15,000, particularly a range of 7,000 to 10,000 is preferred. 5000
If it is less than 15,000, sufficient mechanical strength will not be obtained, and if it exceeds 15,000, roll workability will be extremely poor. This organopolysiloxane can be produced by a known method of ring-opening polymerization of cyclic polysiloxane, which is well known as an oligomer, in the presence of an acid or alkali catalyst. The fine silica powder of component (B) constituting the composition of the present invention includes, for example, fumed silica and precipitated silica, which are well known as reinforcing agents for synthetic rubber, and these have a specific surface area of 50 m2. ² /g
If the specific surface area is less than 50 m 2 /g, it is necessary to have a specific surface area of 50 m ² /g or more, preferably 100 m ² /g or more, since a sufficient vibration-proofing effect will not be provided. In addition, if the amount of this fine silica powder added is less than 10 parts by weight for 100 parts by weight of the organopolysiloxane of component (A), it will not provide a sufficient vibration damping effect, and if it is more than 100 parts by weight, the composition 10 to 100 because physical properties such as mechanical strength decrease when the material is cured.
A range of 30 to 60 parts by weight is required, preferably 30 to 60 parts by weight. Note that this fine silica powder may contain, for example, quartz powder,
Diatomaceous earth or the like may also be used in combination, which provides a better vibration-proofing effect. It is desirable to use 150 parts by weight or less of these quartz powders. The organopolysiloxane used as component (C) in the composition of the present invention has the general formula ():
n=2 to 20, preferably 3 to 10. If n is less than 2 or more than 20, the anti-vibration effect will not be exhibited. This organopolysiloxane is
If it is less than 3 parts by weight based on 100 parts by weight of the organopolysiloxane (A), the resulting cured product will not exhibit sufficient vibration damping effect, so it must be at least 3 parts by weight, and 20 parts by weight or less. Even if the amount exceeds the amount, the vibration damping effect will not be further improved, so the amount is preferably 3 to 20 parts by weight, particularly preferably 5 to 15 parts by weight. The compound used as component (D) added to the composition of the present invention has been used as an anti-aging agent in conventional butyl rubber etc., but in the present invention, it does not have an anti-aging effect, Contributes to improving the vibration isolation effect. The amount of component (D) added is to obtain a good vibration damping effect, and if it is less than 0.01 part by weight based on 100 parts by weight of the organopolysiloxane of component (A), a sufficient vibration damping effect will not be obtained. If it is not added and added in excess of 10 parts by weight, significant vulcanization inhibition will occur.
Should be in the range of 10 parts by weight, the preferred range is
It is 0.03 to 2 parts by weight. The compounds of component (D) may be used alone or in combination of two or more. In addition to the above-mentioned components (A) to (D), the composition of the present invention may contain conventionally known additives, such as improving heat resistance, as long as the necessary physical properties as a vibration-proof rubber are not impaired. Titanium oxide, red iron oxide, cerium oxide, barium zirconate as agents; halogen compounds, antimony oxide as twist-resisting agents; various carbon functional silanes, etc. may be added. The composition of the present invention can be obtained by kneading predetermined amounts of the above-mentioned components (A) to (D) and other components added as necessary, using a two-roll kneader, a Banbury mixer, etc. I can do it. The composition of the present invention is put to practical use as an elastic body by an appropriate vulcanization method. As the vulcanizing agent, for example, an organic peroxide can be used. are dicumyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,
5-di(t-butylperoxy)hexane, 2,
Examples include 5-dimethyl-2,5-di(t-butylperoxy)hexane and 1,1-bis(t-butylperoxy)3,3,5-trimethylcyclohexane. The vibration transmissibility T, which indicates the performance of anti-vibration rubber, can be calculated using the following formula using a degree-of-freedom model:

[Formula] [ω: Angular frequency of external force, ω ₀ : Natural frequency,

〔Example〕

Next, the present invention will be explained in detail with reference to examples.
In the following, "parts" means parts by weight. Examples 1-3 ( _CH3 ) ₂ SiO units 89.85 mol%, ( _CH3 )( _CH2 =
CH) SiO units 0.15 mol% and (C ₆ H ₅ ) ₂ SiO units
100 parts of methylphenylpolysiloxane raw rubber with an average degree of polymerization of 8000 and consisting of 10.0 mol% is wrapped around two rolls, and silica fine powder of Aerosil 200 (product name of Nippon Aerosil Co., Ltd.) with a specific surface area of 200 is applied to this.
m ² /g45 parts and the formula

After adding 10 parts of α,ω-dihydroxymethylphenylpolysiloxane represented by the formula and kneading it uniformly,
Further kneading was carried out at 150℃ for 2 hours using a kneader.
Heat treated. Next, as component (D), 2,6-di-
0.1 part (Example 1), 0.5 part (Example 2), or 1.0 part (Example 3) of t-butyl-4-methylphenol was added, and further 0.5 part of dicumyl peroxide was added. Example 1 thus obtained
Compounds (compositions) of Nos. 3 to 3 have the same composition except for the amount of component (D). 100Kg/cm ² of each compound of Examples 1 to 3,
A sheet with a thickness of 2 mm was obtained by applying pressure and heating at 170° C. for 15 minutes. Using the obtained sheet as a sample,
Mechanical properties and tan δ were measured based on JIS K6301, and the results shown in Table 1 were obtained. Comparative Example 1 Instead of α,ω-dihydroxymethylphenylpolysiloxane, the formula

Example 1 to A sheet sample was prepared in the same manner as in 3, and various properties were measured. The results are shown in Table 1. Comparative Example 2 As component (D), 2,6-di-t-butyl-4-
Example 1 except that methylphenol was not added.
A sheet-like sample was prepared in the same manner as in 3 to 3, and various properties were measured. The results are shown in Table 1.

[Table] Examples 4 to 6 (CH ₃ ) ₂ SiO units 99.83 mol%, (CH ₃ )(CH ₂ =
CH) SiO unit 0.15 mol%, ( _CH3 ) ₂ ( _CH2 =CH)
The average degree of polymerization is 10000, consisting of 0.02 mol% of SiO _0.5 units _.
100 parts of methylvinylpolysiloxane raw rubber
The mixture was wound around a main roll, and 40 parts of Aerosil 200 and 10 parts of α,ω-dihydroxymethylphenylpolysiloxane used in Examples 1 to 3 were added thereto and uniformly kneaded to prepare a compound. Next, this compound is mixed using a kneader.
After heat treatment at 150℃ for 2 hours, as component (D),
0.1 part (Example 4), 0.5 part (Example 5) or 1.0 part (Example 6) of 4,4'-bis(α,α-dimethylbenzyl)diphenylamine (trade name Naugaard 445, manufactured by Koni Royal) , further add 0.5 parts by weight of 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, mix uniformly, and add this.
A sheet with a thickness of 2 mm was obtained by heating under pressure for 15 minutes at 100 kg/cm ² and 170°C. Using the obtained cured sheet as a sample, JIS K6301
When the mechanical properties and tan δ were measured based on this, the results shown in Table 2 were obtained. Comparative example 3 Specific surface area is 19m ² /g instead of Aerosil 200
Sheet-shaped samples were prepared in the same manner as in Examples 4 to 6, except that 40 parts of quartz powder (Crystallite VXS Co., Ltd., product name manufactured by Ryumori Co., Ltd.) was used and Naugard 445 was not used, and various properties were measured. did. The results are shown in Table 2. Comparative Example 4 The following formula was used instead of α,ω-dihydroxymethylphenylpolysiloxane:

Sheet-like samples were prepared in the same manner as in Examples 4 to 6, except that an isopropoxy group-containing polysiloxane represented by the formula was used, and various properties were measured. The results are shown in Table 2. Comparative Example 5 The following formula was used instead of α,ω-dihydroxymethylphenylpolysiloxane:

A sheet sample was prepared in the same manner as in Examples 4 to 6, except that α,ω-dihydroxymethyldiphenylsiloxane represented by the formula: (wherein m and n are 4 on average) was used. Various characteristics were measured. The results are shown in Table 2. Comparative Example 6 Sheet samples were prepared in the same manner as in Examples 4 to 6, except that Naugaard 445 was not added as component (D), and various properties were measured. The results are shown in Table 2.

【table】

[Table] Example 7 100 parts of the same methylphenyl polysiloxane used in Examples 1 to 3 above, Aerosil
45 parts of 200 and 10 parts by weight of the same α,ω-dihydroxymethylphenyl polysiloxane used in Examples 1 to 3 were uniformly kneaded in a kneader, and 150
A compound obtained by heat treatment at ℃ for 2 hours was prepared, and 60 parts of Crystallite VXS, 0.1 part of phenyl-β-naphthylamine (Ouchi Shinko Kagaku Co., Ltd., trade name: Nokrac D), and 2,5-dimethyl-2,5- 0.5 part of bis(t-butylperoxy)hexane was added and kneaded uniformly, and then this was heated under pressure at 100 kg/cm ² and 170° C. for 15 minutes to obtain a sheet with a thickness of 2 mm. Using this sheet as a sample, the mechanical properties and tan δ were measured based on JIS K6301, and the results shown in Table 3 were obtained. Comparative Example 7 Butyl rubber (trade name Butyl 365, Japan Synthetic Rubber
Co., Ltd.) 100 parts, 40 parts of Aerosil 200, 5 parts of zinc white,
1 part of stearic acid and 15 parts of process oil are added and kneaded uniformly to obtain a compound, and 2 parts of sulfur, 0.5 part of 2-mercaptobenzothiazole and tetramethylthiuram monosulfide are added.
Add 1.0 part and knead in the same manner as in Example 7.
A sheet with a thickness of 2 mm was obtained by applying pressure and heating. Using the sheet as a sample, mechanical properties and tan δ were measured in the same manner. The results are shown in Table 3.

【table】

[Table] Examples 8 to 10 (CH ₃ ) ₂ SiO units 79.85 mol%, (CH ₃ )(CH ₂ =
CH) SiO units 0.15 mol% and (C ₆ H ₅ ) ₂ SiO units
100 parts of methylphenylpolysiloxane raw rubber with an average degree of polymerization of 8000 consisting of 20.0 mol% was wrapped around two rolls, and 30 parts (Example 8), 40 parts (Example 9), 60 parts ( Example 10), 10 parts of α,ω-dihydroxymethylphenylpolysiloxane used in Example 1 was added and kneaded uniformly, and then 2,6-di-t-butyl-4- as component (D) was added. 0.5 part of methylphenol and 0.5 part of dicumyl peroxide were added. The composition thus obtained was prepared in the same manner as in Example 1 to a thickness of 2.
When a sheet-like sample of mm was prepared and tan δ was measured, the results shown in Table 4 were obtained. Comparative Examples 8 to 10 In Example 9, Crystallite VXS was used instead of Aerosil 200 (Comparative Example 8), and α, ω-
A composition was prepared in the same manner as in Example 9 except that dihydroxymethylphenylpolysiloxane was not added (Comparative Example 9) and component (D) was not added (Comparative Example 10). Create a sample,
tanδ was measured. The results are shown in Table 4.

〔Effect of the invention〕

As is clear from the results of the Examples, the tan δ of the cured rubber obtained from the anti-vibration rubber composition of the present invention is relatively large and almost unchanged over a wide temperature range. That is, the temperature dependence of the vibration damping effect is extremely small. Therefore, it is useful as a vibration-proof rubber that exhibits a stable vibration-proofing effect over a wide temperature range. Furthermore, it has excellent mechanical properties such as hardness, tensile strength, and elongation.

Claims (1)

[Claims] 1 (A) Average composition formula: R _a SiO _4-a/2 [wherein R is a substituted or unsubstituted monovalent hydrocarbon group, and at least 50% of R is methyl a is a number from 1.99 to 2.02] 100 parts by weight of an organopolysiloxane represented by (B) 10 to 10 parts of fine silica powder with a specific surface area of 50 m ² /g or more
100 parts by weight, (C) General formula: [Formula] [In the formula, n is an integer of 2 to 20] 3 parts by weight or more of organopolysiloxane, and (D) Phenyl-β-naphthylamine, 4,4 '-Bis(α,α-dimethylbenzyl)diphenylamine, N,N'-diphenyl-p-phenylenediamine, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, 2,6-diphenylamine -t-butyl-4-methylphenol, 2,
2'-methylene-bis-(4-ethyl-6-t-
butylphenol), 4,4'-thiobis-(6-
t-butyl-3-methylphenol) and 2
- A vibration-proof rubber composition containing 0.01 to 10 parts by weight of at least one compound selected from the group consisting of mercaptobenzimidazole.