JPS63218762A - Vibration-damping silicone rubber composition - Google Patents

Abstract

PURPOSE:To obtain the titled composition having vibration-damping effects stable for a long period on large vibration displacement in a wide temperature range, by blending a polydiorganosiloxane with specific amounts of a crosslinking auxiliary, a polytetrafluoroethylene filler, etc. CONSTITUTION:100pts.wt. polydiorganosiloxane shown by the formula [R<1> is monofunctional (substituted)hydrocarbon and 0.01-1mol.% R<1> is vinyl group; R<2> is methyl, etc.; n is 3,000-10,000] is blended with (A) 10-200pts.wt., preferably 20-100pts.wt. silica filler (e.g. fumed silica), reinforcing silica having >=50m<2>/g specific surface area, (B) 0.1-10pts.wt. crosslinking auxiliary (e.g. triallyl isocyanurate, etc.), (C) 0.1-20pts.wt., preferably 0.2-5pts.wt. polytetrafluoroethylene filler and (D) 0.05-10pts.wt., preferably 0.1-5pts.wt. organic peroxide (e.g. benzoyl peroxide, etc.).

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a silicone rubber composition used as a vibration-proofing material, and more specifically, the present invention relates to a silicone rubber composition used as a vibration-proof material, and more specifically, under conditions of use where it is exposed to strong vibrations over a wide temperature range, This invention relates to a silicone rubber composition that exhibits stable vibration absorption properties.

[Technical background of the invention and its problems] Conventionally, general organic rubber has been widely used as vibration-proof rubber in order to prevent vibrations and shocks in transportation equipment such as automobiles, various vehicles, and ships.

These organic rubber anti-vibration rubbers have a long track record of use.
Its performance is also fully satisfactory in a relatively narrow temperature range around room temperature. However, recent transportation equipment,
Particularly in automobiles, in parallel with the improvement in performance due to technological advances, personal demands such as interior comfort, comfort, and stability during high-speed driving are increasing. It has become necessary to pay sufficient attention to the reduction of noise and vibration.

Silicone rubber has higher heat resistance and
It is well known that it has a variety of stable properties over a wide range, such as excellent cold resistance. One of those characteristics
Silicone rubber has traditionally been used as a vibration-preventing material due to its stable elasticity. By the way, for example, Japanese Patent Publication No. 47-25285 describes the use of silicone rubber as a filling material for vehicle tires that prevent deflation, but this silicone rubber is used as a foam and is used as a preventive material for the rubber body. It does not only utilize vibration.

Thus, anti-vibration silicone rubber has been generally used in audio equipment and electrical and electronic equipment, such as anti-vibration sheets and rings for small motors, and damping materials for pickup arms. However, since these electrical devices are mainly used indoors, their operating temperature range is narrow, and the vibration-proof rubber parts only need to be small and lightweight, so their operating conditions are not very strict. As a method for improving the anti-vibration properties of silicone rubber, for example, Japanese Patent Application Laid-Open No. 59-176348 discloses a method of adding polyhydric alcohol;
No. 748 discloses a method of using a silica-based filler surface-treated with methyldiphenylsilyl groups, and JP-A-61-168648 discloses a method of adding a phenyl group-containing α,ω-dihydroxypolyorganosiloxane with a low degree of polymerization. The main methods have been to obtain a high loss coefficient (tan δ) for vibration transmission by lowering the crosslinking density of the silicone rubber or reducing the rebound resilience.

However, the decrease in crosslinking density and impact resilience is due to tanδ
However, the permanent deformation of the silicone rubber becomes large, and under severe usage conditions such as those used in transportation equipment as mentioned above, it is difficult to obtain a stable anti-vibration effect over a long period of time. A major problem was pointed out that it would be impossible.

[Object of the Invention] The present invention aims to solve these conventional problems, and at the same time improves the problem of permanent deformation of silicone rubber as a vibration isolating rubber, and at the same time increases tan δ and suppresses large vibrations. The purpose of the present invention is to provide a silicone rubber composition that can provide a stable vibration-proofing effect over a long period of time in a wide temperature range with respect to displacement.

[Structure of the Invention] As a result of various studies to achieve the above object, the present inventors have found that although the vibration-proofing effect of conventional silicone rubber has been solved by making the rubber have a lower modulus (lower rebound resilience). On the other hand, by adding a crosslinking aid and a polytetrafluoroethylene filler to silicone rubber, an extremely excellent vibration damping effect (
It has been discovered that a vibration-proof rubber having a long life and an increase in tan δ can be obtained, and the present invention has been completed.

Compositions in which polytetrafluoroethylene powder is added to silicone rubber have already been described in Japanese Patent Publication No. 43-3980 and Japanese Patent Application Laid-open No. 58-27749, and also in the aforementioned Japanese Patent Application Laid-Open No. 59-176348. The publication also describes its addition as a plasticity regulator.

Furthermore, JP-A-52-11250 describes the addition of a dispersion of emulsion polymerized polytetrafluoroethylene, but in all of these proposals, these polytetrafluoroethylene fillers do not have a vibration-proofing effect. No mention has been made as to whether it is effective or not, but this effect was discovered for the first time in the present invention.

That is, the silicone rubber composition for vibration damping of the present invention comprises (A) 100 parts by weight of polydiorganosiloxane, (
B) Silica filler 10 to 200 parts by weight, (
C) Crosslinking aid 0.1 to 10 parts by weight, (
D) 0.1 to 20 parts by weight of polytetrafluoroethylene filler and (E) 0.05 to 10 parts by weight of organic peroxide.

The polydiorganosiloxane of component (A) used in the present invention has the general formula: % formula % where R1 represents a monovalent substituted or unsubstituted hydrocarbon group, and 0 .01 to 1.0 mol% is a vinyl group, R2 represents a monovalent hydrocarbon group selected from the group consisting of a methyl group, a vinyl group, and a hydroxyl group, and n is a number of 3,000 to io, ooo. )
Substantially linear polymers represented by: R1 other than vinyl groups in this polymer include alkyl groups such as methyl, ethyl, propyl, butyl, hexyl, octyl, decyl, and dodecyl groups; alkyl groups such as allyl; Groups: phenyl group, β-phenylethyl group, 3.3.3-trifluoropropyl group, etc. are exemplified. If the vinyl group in R1 is less than 0.01 mol% on average, curing will not be performed sufficiently;
If the average content exceeds 1.0 mol%, heat resistance may decrease,
It is difficult to obtain silicone rubber with excellent vibration damping properties over a wide target temperature range, and polydiorganosiloxanes with a vinyl group content of 0 to 10 mol% (but not including 0) are used when the average amount of vinyl groups is 0 to 10 mol%. It may be used by blending it so that it is in the range of 0.01 to 1.0 mol%. Also, if the degree of polymerization n is less than 3.000, sufficient mechanical properties cannot be imparted to the cured product, If it exceeds io or ooo, workability will deteriorate.

Although this polydiorganosiloxane is a substantially linear polymer, it may contain a partially branched polymer within the range of possible use.

The silica-based filler used in the present invention as component (B) imparts mechanical properties such as appropriate hardness and tensile strength to the vibration-proof rubber, and includes, for example, fumed silica, wet process silica, and its like. Reinforcing silica or crushed quartz having a specific surface area of 50rrr/g or more, such as fired silica or silica airgel,
Examples include non-reinforcing silica such as diatomaceous earth. These silica fillers may be used as they are, or may be made hydrophobic with a surface treatment agent such as organosiloxane, polydiorganosiloxane, or hexaorganodisilazane.

The blending amount of component (B) is 100% of component (A)! 10 to 200 parts by weight, more preferably 20 to 1 part Ii
00 parts by weight. If the amount of component (B) blended is less than 10 parts by weight, sufficient mechanical strength as a rubber cannot be obtained, and if it exceeds 200 parts by weight, blending becomes difficult, which is not preferred.

The crosslinking aid (C) used in the present invention is effective for increasing the crosslinking density of silicone rubber and reducing permanent deformation (permanent elongation). This component (C) has at least two aliphatic unsaturated bonds in one molecule, and is, for example, a compound having a vinyl group, an allyl group, an acrylic group, and/or a methacrylic group. Such compounds include triallylisocyanurate,
triallyl cyanurate, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, tetramethylolmethanetetramethacrylate,
Tetramethylolmethanetetraacrylate, Tetramethylolmethane trimethacrylate, Tetramethylolmethane triacrylate, Triallyltri'meritate, Diallyl phthalate, Divinylbenzene, N,N'
-Methylenebisacrylamide, ethylene dimethacrylate, 1,3-butylene dimethacrylate, 1,4-butylene dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol diacrylate, etc. It is also possible to use mixtures and partially polymerized products.

The blending amount of component (C) is selected from the range of 0.1 to 10 parts by weight per 100 parts by weight of component (A). (C
If the amount of component () is less than 0.1 part by weight, the desired effect of the present invention cannot be obtained, and if it exceeds 10 parts by weight, the elongation rate and mechanical strength of the rubber will decrease.

The polytetrafluoroethylene filler used as component (D) in the present invention is used to increase the tan δ of silicone rubber, and examples thereof include polytetrafluoroethylene powder and a dispersion containing emulsion polymerized polytetrafluoroethylene. Ru.

As polytetrafluoroethylene powder, it is possible to use any shape such as amorphous, spherical or fibrous, and its size is 500 mm as an average particle diameter.
It is preferable to have an average particle size of 500 μm or less. If the average particle size exceeds 500 μm, the mechanical strength of the rubber will weaken and it will be difficult to obtain a vibration-proofing effect, which is not preferable. It is particularly preferred in the present invention because its diameter is generally more uniform and smaller than that of the polytetrafluoroethylene powder described above.

This emulsion-polymerized polytetrafluoroethylene-containing dispersion may be a commercially available aqueous dispersion, which generally contains 30 to 70% by weight of polytetrafluoroethylene. When adding this to silicone rubber, it may be used as is, or it may be diluted with a water-soluble organic solvent such as alcohol or water, or it may be added to silicone rubber to facilitate its blending. It may also be added by mixing it with silica powder or the like to make a paste.

Note that these polytetrafluoroethylene fillers may be used in a mixed system of powder and dispersion.

The blending amount of component (D) is 0.1 to 20 as the amount of polytetrafluoroethylene per 100 parts by weight of component (A)!
! It is selected from a range of parts by weight, more preferably from 0.2 to 5 parts by weight. If the amount of component (D) is less than 0.1 part by weight, a sufficient vibration damping effect cannot be obtained, and if it exceeds 20 parts by weight, not only will the mechanical strength of the rubber decrease, but the workability of the compound will be extremely poor. Deteriorate.

The organic peroxide component (E) used in the present invention is a vulcanizing agent for curing the silicone rubber composition of the present invention.

Examples of this organic peroxide include benzoyl peroxide, 2,3-dimethylbenzoyl peroxide, 2,4
-dimethylbenzoyl peroxide, 2゜5-dimethylbenzoyl peroxide, tochlorobenzoyl peroxide, p-chlorobenzoyl peroxide, 2
, 4-dichlorobenzoyl peroxide, di-tert-butyl peroxide, 2,5-di-tert-butylperoxy-2,5
-dimethylperoxyhexane, 2,5-di-tert
- Alkyl organic peroxides such as butylperoxy-2,5-dimethylperoxyhexine, tert-butylcumyl peroxide, dicumyl peroxide;
Ester organic peroxides such as tert-butyl perbenzoate; carbonate organic peroxides such as tert-butylperoxyisopropyl carbonate; 1.1-di(tert-butylperoxy)cyclohexane, 1 ,1-di(tert-butylbaroxy)
Examples include peroxyketals such as 3,3.5-trimethylcyclohexane and 2,2-di(tert-butylperoxy)butane.

These organic peroxides can be used alone or as a mixture of two or more.

The blending amount of component (E) is in the range of O.OS to 10 parts by weight per 100 parts by weight of component (A), more preferably O.OS.
It is selected from the range of 1 to 5 parts by weight. If the blending amount of component (E) is less than 0.05 parts by weight, the silicone rubber will not be sufficiently vulcanized, and if it is used in excess of 10 parts by weight, not only will there be no particular effect, but the resulting anti-vibration rubber molding will not be effective. It has a negative effect on the physical properties of the body.

The silicone rubber composition for vibration damping of the present invention includes (A) to (E
) In addition to the ingredients, iron oxide, titanium oxide, aluminum oxide, cerium oxide, lithium hydroxide, zinc oxide, magnesium oxide, calcium carbonate, magnesium silicate, barium oxide, wt acid aluminum, calcium sulfate, barium sulfate, mica , asbestos, carbon black, glass powder, and other inorganic fillers can also be blended.

It is rather a matter of course that heat resistance improvers, flame retardants, colorants, silane coupling agents, processing aids, etc. known in the art may be added. In particular, when using the reinforcing silica of the component (B) mentioned above, the processing aid is used to improve the dispersion of the silica and improve the reinforcing properties of the rubber and the workability of the compound. It is almost always used in compositions. This processing aid is generally a silane or a polyorganosiloxane with a relatively low degree of polymerization having a hydroxyl group or an alkoxy group as a polar group. The organic group bonded to the silicon atom of this polyorganosiloxane is
Examples include a methyl group, a phenyl group, a vinyl group, and a 3°3,3-trifluoropropyl group.

Such processing aids are typically used in silicone rubber compositions in amounts of up to 20% by weight.

The silicone rubber composition of the present invention includes the above (A) to (E).
It is obtained by blending the ingredients and, if necessary, various additives including processing aids, and uniformly kneading them by a conventional method. This composition can be molded by conventional rubber molding methods such as pressing, injection, transfer, extrusion, etc., and a silicone rubber with good anti-vibration properties can be obtained.

[Effects of the Invention] The anti-vibration silicone rubber heat-molded using the anti-vibration silicone rubber composition of the present invention has long-term durability in high-temperature areas where conventional anti-vibration silicone rubbers have not been able to exhibit sufficient performance. It has become possible to use it, and it has a great effect on improving the performance of transportation equipment such as automobiles, noise prevention, comfort, and stability during high-speed driving.

[Examples of the Invention] Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples. In addition, all parts in Examples and Comparative Examples represent parts by weight.

Example 1 100 parts of polydimethylsiloxane (average degree of polymerization 6,000) containing 0.1 mol% of methyl and nylsiloxane units and whose ends are closed with dimethylvinylsilyl groups is charged into a kneader, and then octamethylcyclosiloxane is added to the kneader. 50 parts of fumed silica with a specific surface of $9160 rtr/l surface-treated with tetrasiloxane and 10 parts of α,ω-dimethoxypolydimethylsiloxane with a clay content of 20 cSt at 25°C as a processing aid were added until homogeneous. Kneaded. The compound obtained here was further heated and kneaded at 150° C. for 2 hours, and then cooled to obtain a base compound A.

Take 160 parts of this base compound A, mix 1.0 part of trimethylolpropane trimethacrylate as a crosslinking aid using a two-roll blender, and then add 50 parts of polytetrafluoroethylene (hereinafter referred to as PTFE). A paste consisting of 3.0 parts of emulsion-polymerized PTFE dispersion and 3.0 parts of fine quartz powder containing 3.0 parts of emulsion-polymerized PTFE was gradually added and made uniform, and then divided into sheets with a thickness of 6111 mm, which were heated at 150°C. The water was removed by placing in a dryer for 1 hour, and then after cooling, 0.5 part of the organic peroxide 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane was added to a two-roll blender. A silicone rubber composition was prepared.

Using the silicone rubber composition thus obtained, a sheet with a thickness of 211 and a diameter of 17.78iIII x height of 25
．． Each 4In cylinder was formed by pressing at 170°C for 15 minutes, and vulcanized at 200°C for 4 hours. Then, a dumbbell-shaped test piece and a tanzak-shaped test piece (38 Ill x 5 mn x 2
u) was prepared.

Using these test pieces, hardness, tensile strength, elongation, 1
00% modulus, vibration absorption properties and permanent elongation were measured.

The vibration absorption characteristics were determined by the loss coefficient (ta) using a viscoelastic spectrometer (manufactured by J Iwamoto Seisakusho) using a non-resonant method.
The value of nδ) was determined and evaluated based on the magnitude of the value. The test conditions are as follows.

Test temperature: 120°C Test frequency: 100Hz Tensile average strain: 10% Tensile strain amplitude: 0.316% In addition, permanent elongation was determined by performing a compression fatigue test using a Gutdrich Flexmeter (manufactured by Uejima Seisakusho), and after a repeated deformation test. The permanent elongation was measured. After the test, the permanent elongation was left at room temperature for 1 hour, the ratio to the height at room temperature before the test was calculated, and the vibration durability of the silicone rubber was evaluated based on the magnitude of the measured value. The test conditions are as follows.

Test load 30 bond Number of cycles: 1800r, p, n.

Stroke width: 4.445 mm Test temperature: 100° C. Test time: 2 hours The reason why the test temperature is set to a high temperature is to evaluate the anti-vibration effect and long-term stability in a high temperature range. Further, the hardness was measured using Moon SK6301.

The composition of the obtained silicone rubber is shown in Table 1, and the physical properties of the silicone rubber and the above-mentioned measured values are shown in Table 2. The numbers representing the composition in the table are parts (the same applies hereinafter).

Examples 2 to 5 Using base compound A that was not used in Example 1, the amount of the emulsion polymerized PTFE dispersion added in Example 1 was adjusted to 5 parts (Example 2) and 10 parts (Example 3).
Silicone rubber compositions were prepared with the same composition and under the same conditions except that they were added as a paste with fine quartz powder in the same manner as in Example 1.

Similarly, the amount of crosslinking aid in the silicone rubber composition of Example 2 was changed to 0.3 parts (Example 4) and 3.0 parts (
Silicone rubber compositions having the same composition except for Example 5) were prepared.

Using these silicone rubber compositions, rubbers of the same shape were produced under the same conditions as in Example 1, and the physical properties, vibration absorption properties, and permanent elongation of these were also measured under the same conditions as in Example 1.

The composition of the obtained silicone rubber is shown in Table 1, and the physical properties of the silicone rubber and the above measured values are shown in Table 2.

Example 6 To 160 parts of the base compound A obtained in Example 1, 1.0 part of trimethylolpropane trimethacrylate as a crosslinking aid, 2.0 parts of PTFE powder with an average particle size of 15 μl, and then 2,5-parts of organic peroxide Dimethyl-2,5-di(
A silicone rubber composition was prepared by blending 0.5 part of tert-butylperoxy)hexane using a two-roll blender.

Using this silicone rubber composition, a silicone rubber having the same shape as in Example 1 was produced under the same conditions as in Example 1, and the physical properties, vibration absorption properties, and permanent elongation were measured under the same conditions as in Example 1.

The composition of the obtained silicone rubber is shown in Table 1, and the physical properties of the silicone rubber and the above measured values are shown in Table 2.

Comparative Example 1 160 parts of the base compound A used in Example 1 and the organic peroxide 2,5-dimethyl-2,5-di(ter
A silicone rubber composition was prepared using only 0.5 part of t-butylperoxy)hexane, and then a silicone rubber of the same shape was prepared under the same conditions as in Example 1, and the physical properties were determined under the same conditions as in Example 1. Value, vibration absorption properties and permanent elongation were measured.

The composition of the obtained silicone rubber is shown in Table 1, and the physical properties of the silicone rubber and the above measured values are shown in Table 2.

Comparative Example 2 160 parts of the base compound A used in Example 1, 1.0-trimethylolpropane trimethacrylate as a crosslinking aid, and 2.5-dimethyl-2 organic peroxide.
,5-di(t,ert-butylperoxy)hexane 0
．． A silicone rubber composition was prepared using only 5 parts, and then a silicone rubber of the same shape was prepared under the same conditions as in Example 1, and the physical properties, vibration absorption properties, and permanent elongation were determined under the same conditions as in Example 1. was measured.

The composition of the obtained silicone rubber is shown in Table 1, and the physical properties of the silicone rubber and the above measured values are shown in Table 2.

Comparative Example 3 To 160 parts of the base compound A not used in Example 1, a paste consisting of 5.0 parts of emulsion polymerized PTFE dispersion and 5.0 parts of quartz fine powder was added in the same manner as in Example 1, After removing moisture and cooling, 0.5 part of organic peroxide 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane was blended to prepare a silicone rubber composition. Silicone rubber of the same shape was produced under the same conditions as in Example 1, and its physical properties, vibration absorption properties, and permanent elongation were measured under the same conditions as in Example 1.

The composition of the obtained silicone rubber is shown in Table 1, and the physical properties of the silicone rubber and the above measured values are shown in Table 2.

Table 2 Examples 7 to 12 Polydimethylsiloxane (average degree of polymerization 5,000) terminated with trimethylsilyl groups and containing 5 mol% diphenylsiloxane units and 0.2 mol% methyl and nylsiloxane units (average degree of polymerization 5,000) 100 parts In contrast, 50 parts of the same fumed silica used in Example 1, 2 parts as a processing aid,
10 parts of α,ω-dimethoxypolydimethylsiloxane having a viscosity of 30 cSt at 5°C and containing 20 mol% of diphenylsiloxane units and 5 parts of a dispersion of the same emulsion polymerized PTFE used in Example 1 were uniformly mixed with a Ni-Goo. After kneading, the mixture was further heated and kneaded at 150°C for 2 hours, and then cooled to 50°C or lower to obtain a base compound B.

A silicone rubber composition (Example 7) was prepared by blending 0.6 part of organic peroxide dicumyl peroxide with 165 parts of this base compound B, and then blending 1 part of trimethylolpropane trimethacrylate as a crosslinking aid. A silicone rubber composition containing 1 part of propane triacrylate (Example 8), a silicone rubber composition containing 1 part of divinylbenzene (Example 9),
A silicone rubber composition (Example 10) containing one part of triallyl isocyanurate was prepared.

Similarly, silicone rubber compositions were also prepared in which the amounts of triallylisocyanurate in Example 10 were 3.0 parts (Example 11) and 5.0 parts (Example 12), respectively.

Using these silicone rubber compositions, silicone rubber of the same shape as in Example 1 was produced under the same conditions as in Example 1.
The physical properties, vibration absorption properties, and permanent elongation were measured under the same conditions.

The composition of the obtained silicone rubber is shown in Table 3, and the physical properties of the silicone rubber and the above measured values are shown in Table 4.

Comparative Example 4 A silicone rubber composition was prepared by blending 0.6 parts of organic peroxide dicumyl peroxide with 165 parts of the base compound B used in Example 7, and a silicone rubber composition of the same shape was prepared under the same conditions as in Example 1. was prepared, and the physical properties, vibration absorption properties, and permanent elongation were measured under the same conditions as in Example 1.

The composition of the obtained silicone rubber is shown in Table 3, and the physical properties of the silicone rubber and the above measured values are shown in Table 4.

Example 13 A base compound having the same composition as that used in Example 7 except that the fumed silica of base compound B was replaced with wet process silica having a specific surface area of 180 rrr/g was prepared, and 165 parts of this base compound was added with organic peroxide. A silicone rubber composition was prepared by blending 0.6 part of dicumyl peroxide and then 1.0 part of trimethylolpropane trimethacrylate.

Using this silicone rubber composition, a silicone rubber having the same shape as in Example 1 was produced under the same conditions as in Example 1, and the physical properties, vibration absorption properties, and permanent elongation were measured under the same conditions as in Example 1.

The composition of the obtained silicone rubber is shown in Table 3, and the physical properties of the silicone rubber and the above measured values are shown in Table 4.

(Left below) Example 14 Polymethyl (3,
To 100 parts of 3,3-trifluoropropyl)siloxane (average degree of polymerization 6,000), 50 parts of the same fumed silica as used in Example 1 and emulsion polymerized PTFE were added.
A base compound was prepared under the same conditions as in Example 7 using 5 parts of the dispersion and 10 parts of the same processing aid as used in Example 7, and 165 parts of this base compound was added with Example 1. A silicone rubber composition was prepared by blending 0.5 part of the same organic peroxide as that used in 1. and then 1.0 part of trimethylolpropane trimethacrylate as a crosslinking aid.

Using this silicone rubber composition, a silicone rubber having the same shape as in Example 1 was produced under the same conditions as in Example 1, and the physical properties, vibration absorption properties, and permanent elongation were measured under the same conditions as in Example 1.

The composition of the obtained silicone rubber is shown in Table 3, and the physical properties of the silicone rubber and the above measured values are shown in Table 4.

Example 15 A base compound was prepared under the same conditions as in Example 14 except that the amount of fumed silica was changed to 30 parts and the amount of processing aid was changed to 6 parts. 0.5 part of the same organic peroxide as used in Example 1 was blended, and then 1.0 part of trimethylolpropane trimethacrylate was added as a crosslinking aid.
A silicone rubber composition was prepared.

Using this silicone rubber composition, a silicone rubber having the same shape as in Example 1 was produced under the same conditions as in Example 1, and the physical properties, vibration absorption properties, and permanent elongation were measured under the same conditions as in Example 1.

The composition of the obtained silicone rubber is shown in Table 3, and the physical properties of the silicone rubber and the above measured values are shown in Table 4.

Example 16.17 For 100 parts of the same polydimethylsiloxane used in Example 1, 50 parts of fumed silica with a specific surface area of 180 rrr/g surface-treated with hexamethyldisilazane,
6 parts of α,ω-dihydroxypolydimethylsiloxane having a viscosity of 50 cSt at 25°C, 1.0 part of tetramethylolmethanetetramethacrylate as a crosslinking aid, P
A base compound C was prepared by uniformly kneading 3.0 parts of a dispersion of polymerized PTFE containing 70% TFE and 0% by weight using a kneader.

0.5 parts of the same organic peroxide used in Example 1 was blended with 160 parts of this base compound C to prepare a silicone rubber composition.

Similarly, a silicone rubber composition was prepared by adding 1.2 parts of a paste consisting of benzoyl peroxide and silicone oil in a weight ratio of 1:1 to 160 parts of base compound C.

Using these silicone rubber compositions, silicone rubber of the same shape as in Example 1 was produced under the same conditions as in Example 1.
The physical properties, vibration absorption properties, and permanent elongation were measured under the same conditions.

The composition of the obtained silicone rubber is shown in Table 3, and the physical properties of the silicone rubber and the above measured values are shown in Table 4.

Example 18 The fumed silica of base compound C used in Example 16 had a specific surface area of 20 Or&/g without surface treatment.
A completely identical compound was prepared except that 50 parts of fumed silica was used, and 0.5 part of the same organic peroxide as used in Example 1 was blended with 160 parts of this base compound to form a silicone rubber. A composition was prepared.

Using this silicone rubber composition, a silicone rubber having the same shape as in Example 1 was produced under the same conditions as in Example 1, and the physical properties, vibration absorption properties, and permanent elongation were measured under the same conditions as in Example 1.

The composition of the obtained silicone rubber is shown in Table 3, and the physical properties of the silicone rubber and the above measured values are shown in Table 4.

(Left below) $1 = Contains 0.1 mol% of methyl and nylsiloxane units,
Average degree of polymerization: 6,000. -2: Surface treated with octamethylcyclotetrasiloxane, specific surface area = 160rrr
/g, *8 Nidiphenylsiloxane unit 20 mol%
Viscosity at 25°C = 30cst, $9:
Contains 0.5 mol% of methylvinylsiloxane units, average degree of polymerization 6,000. 10: Surface treated with hexamethyldisilazane, specific surface area = 180//g.

11: specific surface area = 200rtr/g, umbrella 12;
Viscosity at 25°C = 50C3t, Viscosity 13: The same amount of silicone oil was used as a paste.

As is clear from the above Examples and Comparative Examples, the silicone rubber composition for vibration isolation of the present invention exhibits good vibration absorption properties and excellent permanent deformation under conditions of relatively large vibration displacement at high temperatures. Therefore, it can be said that it is an extremely suitable material for vibration-proof rubber for transportation equipment, etc.

Claims (6)

[Claims] (1) (A) Polydiorganosiloxane 100 parts by weight, (B) Silica filler 10 to 200 parts by weight, (C) Crosslinking aid 0.1 to 10 parts by weight, (D) Polytetrafluoroethylene filler 0 .1~2
0 parts by weight and (E) 0.05 to 10 parts by weight of an organic peroxide. (2) The polydiorganosiloxane of component (A) has the general formula: R^2(R^1_2SiO)_nSiR^1_2R^2
(In the formula, R^1 represents a monovalent substituted or unsubstituted hydrocarbon group, and among these hydrocarbon groups, 0.01 to 1.0
% by mole is a vinyl group, R^2 represents a monovalent hydrocarbon group selected from the group consisting of a methyl group, a vinyl group and a hydroxyl group, and n represents a number from 3,000 to 10,000. ) The silicone rubber composition for vibration isolation according to claim 1. (3) The silica filler of component (B) has a specific surface area of 50 m
Claim 1 which is reinforcing silica of ^2/g or more
The silicone rubber composition for anti-vibration according to item 1 or 2. (4) The silicone rubber composition for vibration isolation according to claim 1 or 2, wherein the silica filler as component (B) is fumed silica. (5) The silicone rubber composition for vibration isolation according to claim 1 or 2, wherein the silica-based filler as component (B) is fumed silica surface-treated with an organosilicon compound. (6) The vibration damping according to any one of claims 1 to 5, wherein a dispersion containing emulsion polymerized polytetrafluoroethylene is used as the polytetrafluoroethylene filler of component (D). Silicone rubber composition for use.