CA1162687A - Silicone rubber composition for drive shaft seals - Google Patents
Silicone rubber composition for drive shaft sealsInfo
- Publication number
- CA1162687A CA1162687A CA000360008A CA360008A CA1162687A CA 1162687 A CA1162687 A CA 1162687A CA 000360008 A CA000360008 A CA 000360008A CA 360008 A CA360008 A CA 360008A CA 1162687 A CA1162687 A CA 1162687A
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- silicone rubber
- drive shaft
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/34—Silicon-containing compounds
- C08K3/36—Silica
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/34—Silicon-containing compounds
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/04—Oxygen-containing compounds
- C08K5/14—Peroxides
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L83/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
- C08L83/04—Polysiloxanes
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
- C08G77/04—Polysiloxanes
- C08G77/12—Polysiloxanes containing silicon bound to hydrogen
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
- C08G77/04—Polysiloxanes
- C08G77/20—Polysiloxanes containing silicon bound to unsaturated aliphatic groups
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
- C08G77/70—Siloxanes defined by use of the MDTQ nomenclature
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- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Sealing Material Composition (AREA)
Abstract
Abstract of the Disclosure A drive shaft seal prepared from organopolysiloxane gum, a reinforcing silica filler, diatomaceous earth, organohydrogenpolysiloxanel and organic peroxide has improved oil leakage and noise reduction.
Description
l 162687 This invention describes a silicone rubber composition to be used for drive shaft seals. More specifically, this invention describes a heat-vulcanizable silicone rubber composition which is optimal for use in the manufacture of drive shaft seals. Further, this invention relates to an improved drive shaft seal.
It is known that silicone rubber can be used for drive shaft seals in cars because it has excellent physical properties, such as oil resistance and durability. However, when the above-mentioned drive shaft seal is repeatedly subjected to friction when it rubs on the surface of the drive shaft, the noise generated by the friction is unpleasant and is a source of anxiety for the driver of the car. The abrasion due to the friction widens the space between the rubbing surface and the sealing material resulting in oil leakage. The traditional silicone rubber compositions cannot eliminate the above-mentioned factors of anxiety.
The use of diatomaceous earth in silicone rubber is known. It is also known to use diatomaceous earth in silicone rubber compositions which are to be used for oil resistance in manufacturing oil seals, as shown by Loraine et al. in U.S. Patent No. 3,468,838 issued September 23, 1969.
Loraine et al. show that magnesium oxide is required to l 162687 provide silicone rubber with sufficient oil resistance to be used as oil seals. Christe in U.S. Patent No. 3,865,778 issued February 11, 1975, also shows that magnesium oxide is required to provide sufficient oil resistance to silicone rubber which contains diatomaceous earth.
Silicone rubber compositions for use as shaft seals and shaft seals made from such compositions are described by Honma et al. in U.S. Patent No. 4,116,920 issued September 26, 1978. Honma et al. describe these shaft seal compositions as being 100 parts by weight of a heat curable organopolysiloxane rubber, 5 to 100 parts by weight of a reinforcing silica filler, 5 to 100 parts by weight of diatomaceous earth, 2 to 100 parts by weight of an acicular platy mineral powder and 0.1 to 10 parts by weight of an organic peroxide. The drive shaft seals made from the compositions of this invention are an improvement over the shaft seals of Honma et al., especially in noise reduction and oil leakage propertles.
Hatanaka et al. in Japanese Kokai Patent No. Sho 53(1978)-141362, published December 9, 1978, describe heat vulcanizable silicone rubber comprising 100 parts by weight of an organopolysiloxane, 10 to 300 parts by weight of an organosilazane treated fine silica powder, 0.01 to 10 parts by weight of an organohydrogenpolysiloxane, and a catalytic amount of an organic peroxide. In Example 2, Hatanaka et al.
describe precipitated silica and diatomaceous earth.
Hanaka et al. do not describe their materials as having oil resistance or usefulness in the manufacture of drive shaft seals.
The purpose of this invention i9 to eliminate the above-mentioned drawbacks and to provide an abrasion-resistant, oil-resistant, durable silicone rubber composition to be used for drive shaft seals which constitutes a motor oil seal and does not generate noise by .
friction with the rubbing surface of the drive shaft. Drive shaft seals manufactured from organopolysiloxane gum, reinforcing silica filler, diatomaceous earth, organohydrogenpolysiloxane, and organic peroxide provide the desired properties.
This invention relates to a silicone rubber composition to be used for drive shaft seals consisting essentially of (i) 100 parts by weight of an organopolysiloxane gum having the average unit formula RaSiO4-a where each R represents a substituted or unsubstituted monovalent hydrocarbon radical and a has a value of 1.98 to
It is known that silicone rubber can be used for drive shaft seals in cars because it has excellent physical properties, such as oil resistance and durability. However, when the above-mentioned drive shaft seal is repeatedly subjected to friction when it rubs on the surface of the drive shaft, the noise generated by the friction is unpleasant and is a source of anxiety for the driver of the car. The abrasion due to the friction widens the space between the rubbing surface and the sealing material resulting in oil leakage. The traditional silicone rubber compositions cannot eliminate the above-mentioned factors of anxiety.
The use of diatomaceous earth in silicone rubber is known. It is also known to use diatomaceous earth in silicone rubber compositions which are to be used for oil resistance in manufacturing oil seals, as shown by Loraine et al. in U.S. Patent No. 3,468,838 issued September 23, 1969.
Loraine et al. show that magnesium oxide is required to l 162687 provide silicone rubber with sufficient oil resistance to be used as oil seals. Christe in U.S. Patent No. 3,865,778 issued February 11, 1975, also shows that magnesium oxide is required to provide sufficient oil resistance to silicone rubber which contains diatomaceous earth.
Silicone rubber compositions for use as shaft seals and shaft seals made from such compositions are described by Honma et al. in U.S. Patent No. 4,116,920 issued September 26, 1978. Honma et al. describe these shaft seal compositions as being 100 parts by weight of a heat curable organopolysiloxane rubber, 5 to 100 parts by weight of a reinforcing silica filler, 5 to 100 parts by weight of diatomaceous earth, 2 to 100 parts by weight of an acicular platy mineral powder and 0.1 to 10 parts by weight of an organic peroxide. The drive shaft seals made from the compositions of this invention are an improvement over the shaft seals of Honma et al., especially in noise reduction and oil leakage propertles.
Hatanaka et al. in Japanese Kokai Patent No. Sho 53(1978)-141362, published December 9, 1978, describe heat vulcanizable silicone rubber comprising 100 parts by weight of an organopolysiloxane, 10 to 300 parts by weight of an organosilazane treated fine silica powder, 0.01 to 10 parts by weight of an organohydrogenpolysiloxane, and a catalytic amount of an organic peroxide. In Example 2, Hatanaka et al.
describe precipitated silica and diatomaceous earth.
Hanaka et al. do not describe their materials as having oil resistance or usefulness in the manufacture of drive shaft seals.
The purpose of this invention i9 to eliminate the above-mentioned drawbacks and to provide an abrasion-resistant, oil-resistant, durable silicone rubber composition to be used for drive shaft seals which constitutes a motor oil seal and does not generate noise by .
friction with the rubbing surface of the drive shaft. Drive shaft seals manufactured from organopolysiloxane gum, reinforcing silica filler, diatomaceous earth, organohydrogenpolysiloxane, and organic peroxide provide the desired properties.
This invention relates to a silicone rubber composition to be used for drive shaft seals consisting essentially of (i) 100 parts by weight of an organopolysiloxane gum having the average unit formula RaSiO4-a where each R represents a substituted or unsubstituted monovalent hydrocarbon radical and a has a value of 1.98 to
2.02, (ii) 5 to 100 parts by weight of a reinforcing silica filler, (iii) 5 to 100 parts by weight of diatomaceous earth, (iv) 0.1 to 10 parts by weight of an organohydrogenpolysiloxane having the average unit formula RbHCS i 4-b- c ~ 162687 where R is defined above, b has a value of 1 to 2, c has a value of 0.1 to 1.2, and the sum of b + c has a value of 1.8 to 2.2, said organohydrogenpolysiloxane having at least three silicon-bonded hydrogen atoms per molecule, and tv) 0.1 to 10 parts by weight OL an organic peroxide.
Component (i) is a principal component of the usual silicone rubber and is a high molecular weight straight or slightly branched-chain organopolysiloxane which is gummy at room temperature. The organic radicals can be methyl, ethyl, vinyl, phenyl or trifluoropropyl radicals, and at least 50%
of all the organic radicals in component (i) are preferably methyl. The endblocking groups can be organosiloxy groups having attached radicals selected from hydroxyl, alkoxyl, methyl, vinyl and phenyl radicals. However, the organopolysiloxane is not limited to these examples.
A reinforcing silica filler, component (ii), can be fumed silica, precipitated silica, or a dehydrated form of this silica. Component (ii) is indispensable for the mechanical strength of the silicone rubber and the quantity of this component to be added is 5 to 100 parts by weight, preferably 20 to 70 parts by weight relative to 100 parts by weight of component (i).
Diatomaceous earth as ccmponent (iii) is indispensable to the hardness and oil resistance of the silicone rubber. When a silica bulking agent other than the above is used, the drive shaft seal undergoes violent i 162687 friction resulting in the generation of loud noise. The use of diatomaceous earth does not cause such noise. The quantity of component (iii) to be added is 5 to 100 parts by weight, preferably 20 to 90 parts by weight relative to 100 parts by weight of component (i).
Organohydrogenpolysiloxane, component (iv), is an important component which displays the characteristic of this invention. It imparts the property of slipperiness, the property of reducing noise and the abrasion resistance to the silicone rubber and provides sealability with respect to motor oil. Component (iv) is an organohydrogenpolysiloxane having at least three silicon-bonded hydrogen atoms per molecule. The organohydrogenpolysiloxanes have an average unit formula RbHC04-b-c where R is the same as defined above, preferably methyl, b has a value of 1 to 2, c has a value of 0.1 to 1.2, preferably 0.1 to 1~ and the sum of b + c has a value of 1.8 to 2.2. The quantity of this component to be added for optimum properties depends on the number of silicon-atom-bonded hydrogen atoms, but is in the range of 0.1 to 10 parts by weight relative to 100 parts by weight of component (i). When this quantity is less than 0.1 part by weight, the purpose of this invention cannot be accomplished.
On the other hand, when this quantity exceeds 10 parts by weight, the resulting composition exhibits foaming and ~ 162687 stickiness at the time of vulcanization molding processes.
The R of the average unit ~ormula of this component is selected rom the same organic radicals defined for component (i) and is preferably methyl.
An organic peroxide, component (v), is a traditional catalyst used for heat-setting silicone rubber compositions. Examples of organic peroxide are benzoyl peroxide, t-butyl perbenzoate, 2,4-dichlorobenzoyl peroxide, monochlorobenzoyl peroxide, dicumyl peroxide, 2~5~bis-(t-butylperoxy)-2,5-dimethylhexane. The amount of organic peroxide can be from 0.1 to 10 parts by weight relative to 100 parts by weight of component (i), preferably from 0.1 to 2 parts by weight.
Components (i)-(v) can each be a single compound or they can be mixtures of two or more compounds. The silicone rubber composltion produced by the method of this invention can be produced by simply blending the components (i)-(v) mentioned above. However, if necessary, additives such as diphenylsilanediol, diphenylmethylsilanol and low molecular weight organosilicon compounds such as hydroxyl endbloc~ed polydimethylsiloxane which have low degrees of polymerization can be used. Other additives which can be used are mica powder, graphite, polytetrafluoroethylene (Teflon~) powder, magnesium oxide, zinc oxide, pigments, heat-stability agents and oil-resistant agents. The order of blending the components (i)-(v) is arbitrary; however, the best procedure is to first blend component (i) with component (ii) using a kneader mixer. The resulting mixture is then mixed with components (iii) and (iv) using a Banbury mixer or a two-roll mixer, and then mixed with component (v) using a two-roll mixer.
Components (i)-(iii), make up a silicone rubber composition prepared by the method mentioned above. This composition is heat-treated at 100-200C for several minutes to several hours under elevated or ambient pressure, components (iv) and (v) are added, and then it can be vulcanized. The cured silicone rubber product exhibits excellent mechanical properties, oil resistance, abrasion resistance and tight sealability and does not generate noise so that it is advantageously used for the manufacture of drive shaft seals.
This invention will be further explained by using demonstrative examples. "Part" in the examples means "part by weight."
Example 1 A composition was prepared by placing in a Banbury mixer r 100 parts of a dimethylvinylsiloxy endblocked polydiorganosiloxane gum having 99.84 mol % dimethylsiloxane units and 0.16 mol % methylvinylsiloxane units, and having a plasticity at 25C of 160; 35 parts of precipitated silica 1 162~8~
having a specific surface area of 240 m2/g; 60 parts of diatomaceous earth and 3 parts of diphenylsilanediol. The resulting mixture was kneaded well at room temperature and then at 170C for 2 hours. The mixture was cooled to a temperature of ~60C and then combined with 10 parts of fine mica powder, trimethylsiloxy endblocked methylhydrogen-polysiloxane (in the quantity given in Table I); having dimethylsiloxane units and methylhydrogensiloxane units in a l:l molar ratio and a viscosity of 0.00005 m2/g, and 0.5 part of a paste of 50 weight percent silicone oil and 50 weight percent 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane. The resulting silicone rubber mixture was homogeneously kneaded using a two-roll mixer. This silicone rubber composition was cured using a hot press at 170C for lO minutes and then vulcanized in an oven at 200C for 4 hours. The hardness and tensile elongation at break (a #3 dumbell was used) of a 2 mm-thick sheet were measured by the methods of JIS K6301 (equivalent to ASTM D 412 for tensile and elongation and equivalent to ASTM 2240 for hardness). A silicone rubber composition identical to that mentioned above was cured in a metal mold for an oil seal at an elevated temperature under the same conditions as given above. The molded product was placed in a rotary tester for oil seal testing. The drive shaft of the tester was rotated at the rate of 3,000 rpm, and 5 observers slowly walked away from the tester in order to ~ 162687 determine the distance at which the frictional noise was no longer heard. Under the same conditions, the shaft was continuously rotated for 24 hours in order to measure the volume of test lubricant leakage which was used as a measure of the sealability of the drive shaft seal. The oil resistance was measured by the following method. Motor oil lOW-30 and JIS swelling oil #3 were each placed separately in reflux tubes. A test specimen which had been vulcanized by the method mentioned above was immersed in the above-mentioned lubricant. The tube was then allowed to stand in a thermostat at 150C for about 70 hours. The change in volume of the test specimen was measured. The JIS
swelling oil #3 had a kinetic viscosity in the range of 31.96 x 10-6 to 34.18 x 10-6 m2/g, an aniline point of 69.5 +1, and a flash point of 162.7C.
For comparison, the composition was prepared by the method of Example 1 with the exception that methylhydrogen-polysiloxane was not used. The test piece was prepared and tested by the methods mentioned above. The results are given in Table 1.
~ 182687 Example 2 A composition was prepared by placing in a kneader and then homogeneously kneading 100 parts of a dimethyl-vinylsiloxy endblocked polydiorganosiloxane gum having 95 mol % dimethylsiloxane units, 0.2 mol % methylvinyl-siloxane units, and 4.8 mol % methylphenylsiloxane units, and having a plasticity at 25C of 130, 50 parts of fumed silica having a specific surface area of 200 m2/g, 10 parts of a hydroxyl endblocked polydimethylsiloxane with a low degree of polymerization, 0.5 part of vinyltriethoxysilane and 0.5 part of polytetrafluoroethylene powder (Teflon~ 6CJ powder from Mitsui Fluorochemical Co., Tokyo, Japan). The resulting mixture was further kneaded at 150C for 2 hours. The mixture was cooled to a temperature of ~ 60C and then combined with 20 parts of diatomaceous earth, 0.5 part red iron oxide, methylhydrogencyclotetrasiloxane (in the quantity given in Table 2) and 0.6 part of 2,4-dichlorobenzoyl peroxide. The resulting mixture was homogeneously kneaded using a two-roll mixer. This composition was cured using a hot press at 120C for 10 minutes and then vulcanized in an oven at 250C for 4 hours. The properties of the vulcanized silicone rubber composition were measured by methods described in Example 1. For a comparative example, the composition was prepared by the same method as mentioned above with the exception that methylhydrogencyclotetra-siloxane was not added. A test specimen was prepared and measured by the same methods as described above. me results are given in Table 2.
~ 162687 ,~ O u~ O ~ O O u~ ~ ~ o r~ u~ ~ u~
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.q ~ er .~
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Component (i) is a principal component of the usual silicone rubber and is a high molecular weight straight or slightly branched-chain organopolysiloxane which is gummy at room temperature. The organic radicals can be methyl, ethyl, vinyl, phenyl or trifluoropropyl radicals, and at least 50%
of all the organic radicals in component (i) are preferably methyl. The endblocking groups can be organosiloxy groups having attached radicals selected from hydroxyl, alkoxyl, methyl, vinyl and phenyl radicals. However, the organopolysiloxane is not limited to these examples.
A reinforcing silica filler, component (ii), can be fumed silica, precipitated silica, or a dehydrated form of this silica. Component (ii) is indispensable for the mechanical strength of the silicone rubber and the quantity of this component to be added is 5 to 100 parts by weight, preferably 20 to 70 parts by weight relative to 100 parts by weight of component (i).
Diatomaceous earth as ccmponent (iii) is indispensable to the hardness and oil resistance of the silicone rubber. When a silica bulking agent other than the above is used, the drive shaft seal undergoes violent i 162687 friction resulting in the generation of loud noise. The use of diatomaceous earth does not cause such noise. The quantity of component (iii) to be added is 5 to 100 parts by weight, preferably 20 to 90 parts by weight relative to 100 parts by weight of component (i).
Organohydrogenpolysiloxane, component (iv), is an important component which displays the characteristic of this invention. It imparts the property of slipperiness, the property of reducing noise and the abrasion resistance to the silicone rubber and provides sealability with respect to motor oil. Component (iv) is an organohydrogenpolysiloxane having at least three silicon-bonded hydrogen atoms per molecule. The organohydrogenpolysiloxanes have an average unit formula RbHC04-b-c where R is the same as defined above, preferably methyl, b has a value of 1 to 2, c has a value of 0.1 to 1.2, preferably 0.1 to 1~ and the sum of b + c has a value of 1.8 to 2.2. The quantity of this component to be added for optimum properties depends on the number of silicon-atom-bonded hydrogen atoms, but is in the range of 0.1 to 10 parts by weight relative to 100 parts by weight of component (i). When this quantity is less than 0.1 part by weight, the purpose of this invention cannot be accomplished.
On the other hand, when this quantity exceeds 10 parts by weight, the resulting composition exhibits foaming and ~ 162687 stickiness at the time of vulcanization molding processes.
The R of the average unit ~ormula of this component is selected rom the same organic radicals defined for component (i) and is preferably methyl.
An organic peroxide, component (v), is a traditional catalyst used for heat-setting silicone rubber compositions. Examples of organic peroxide are benzoyl peroxide, t-butyl perbenzoate, 2,4-dichlorobenzoyl peroxide, monochlorobenzoyl peroxide, dicumyl peroxide, 2~5~bis-(t-butylperoxy)-2,5-dimethylhexane. The amount of organic peroxide can be from 0.1 to 10 parts by weight relative to 100 parts by weight of component (i), preferably from 0.1 to 2 parts by weight.
Components (i)-(v) can each be a single compound or they can be mixtures of two or more compounds. The silicone rubber composltion produced by the method of this invention can be produced by simply blending the components (i)-(v) mentioned above. However, if necessary, additives such as diphenylsilanediol, diphenylmethylsilanol and low molecular weight organosilicon compounds such as hydroxyl endbloc~ed polydimethylsiloxane which have low degrees of polymerization can be used. Other additives which can be used are mica powder, graphite, polytetrafluoroethylene (Teflon~) powder, magnesium oxide, zinc oxide, pigments, heat-stability agents and oil-resistant agents. The order of blending the components (i)-(v) is arbitrary; however, the best procedure is to first blend component (i) with component (ii) using a kneader mixer. The resulting mixture is then mixed with components (iii) and (iv) using a Banbury mixer or a two-roll mixer, and then mixed with component (v) using a two-roll mixer.
Components (i)-(iii), make up a silicone rubber composition prepared by the method mentioned above. This composition is heat-treated at 100-200C for several minutes to several hours under elevated or ambient pressure, components (iv) and (v) are added, and then it can be vulcanized. The cured silicone rubber product exhibits excellent mechanical properties, oil resistance, abrasion resistance and tight sealability and does not generate noise so that it is advantageously used for the manufacture of drive shaft seals.
This invention will be further explained by using demonstrative examples. "Part" in the examples means "part by weight."
Example 1 A composition was prepared by placing in a Banbury mixer r 100 parts of a dimethylvinylsiloxy endblocked polydiorganosiloxane gum having 99.84 mol % dimethylsiloxane units and 0.16 mol % methylvinylsiloxane units, and having a plasticity at 25C of 160; 35 parts of precipitated silica 1 162~8~
having a specific surface area of 240 m2/g; 60 parts of diatomaceous earth and 3 parts of diphenylsilanediol. The resulting mixture was kneaded well at room temperature and then at 170C for 2 hours. The mixture was cooled to a temperature of ~60C and then combined with 10 parts of fine mica powder, trimethylsiloxy endblocked methylhydrogen-polysiloxane (in the quantity given in Table I); having dimethylsiloxane units and methylhydrogensiloxane units in a l:l molar ratio and a viscosity of 0.00005 m2/g, and 0.5 part of a paste of 50 weight percent silicone oil and 50 weight percent 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane. The resulting silicone rubber mixture was homogeneously kneaded using a two-roll mixer. This silicone rubber composition was cured using a hot press at 170C for lO minutes and then vulcanized in an oven at 200C for 4 hours. The hardness and tensile elongation at break (a #3 dumbell was used) of a 2 mm-thick sheet were measured by the methods of JIS K6301 (equivalent to ASTM D 412 for tensile and elongation and equivalent to ASTM 2240 for hardness). A silicone rubber composition identical to that mentioned above was cured in a metal mold for an oil seal at an elevated temperature under the same conditions as given above. The molded product was placed in a rotary tester for oil seal testing. The drive shaft of the tester was rotated at the rate of 3,000 rpm, and 5 observers slowly walked away from the tester in order to ~ 162687 determine the distance at which the frictional noise was no longer heard. Under the same conditions, the shaft was continuously rotated for 24 hours in order to measure the volume of test lubricant leakage which was used as a measure of the sealability of the drive shaft seal. The oil resistance was measured by the following method. Motor oil lOW-30 and JIS swelling oil #3 were each placed separately in reflux tubes. A test specimen which had been vulcanized by the method mentioned above was immersed in the above-mentioned lubricant. The tube was then allowed to stand in a thermostat at 150C for about 70 hours. The change in volume of the test specimen was measured. The JIS
swelling oil #3 had a kinetic viscosity in the range of 31.96 x 10-6 to 34.18 x 10-6 m2/g, an aniline point of 69.5 +1, and a flash point of 162.7C.
For comparison, the composition was prepared by the method of Example 1 with the exception that methylhydrogen-polysiloxane was not used. The test piece was prepared and tested by the methods mentioned above. The results are given in Table 1.
~ 182687 Example 2 A composition was prepared by placing in a kneader and then homogeneously kneading 100 parts of a dimethyl-vinylsiloxy endblocked polydiorganosiloxane gum having 95 mol % dimethylsiloxane units, 0.2 mol % methylvinyl-siloxane units, and 4.8 mol % methylphenylsiloxane units, and having a plasticity at 25C of 130, 50 parts of fumed silica having a specific surface area of 200 m2/g, 10 parts of a hydroxyl endblocked polydimethylsiloxane with a low degree of polymerization, 0.5 part of vinyltriethoxysilane and 0.5 part of polytetrafluoroethylene powder (Teflon~ 6CJ powder from Mitsui Fluorochemical Co., Tokyo, Japan). The resulting mixture was further kneaded at 150C for 2 hours. The mixture was cooled to a temperature of ~ 60C and then combined with 20 parts of diatomaceous earth, 0.5 part red iron oxide, methylhydrogencyclotetrasiloxane (in the quantity given in Table 2) and 0.6 part of 2,4-dichlorobenzoyl peroxide. The resulting mixture was homogeneously kneaded using a two-roll mixer. This composition was cured using a hot press at 120C for 10 minutes and then vulcanized in an oven at 250C for 4 hours. The properties of the vulcanized silicone rubber composition were measured by methods described in Example 1. For a comparative example, the composition was prepared by the same method as mentioned above with the exception that methylhydrogencyclotetra-siloxane was not added. A test specimen was prepared and measured by the same methods as described above. me results are given in Table 2.
~ 162687 ,~ O u~ O ~ O O u~ ~ ~ o r~ u~ ~ u~
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, o U~ o ~ o . . er 0 o ~ o ~1 ~ O ~ ~ I O ~ er ' ~O
.q ~ er .~
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o J- ~n ~
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~ v ~ v ~~ ~ u~ ~ ~ ~rl o ~ 1 s0 ~ 0 a) ~ v tl~ ~?
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(a ~ ~ d~ ~ la u~ O o u~ ~ ~ aJ ~a -- ~ ~ ~ ~ u~ ~
"~ ~ _ v ~ 0~ P~ a~ s :~ o ~-,, c a~ ~ s o ~ ~ o C JJ ~ la c ~ ~ O ~a ~ -- X v ~a ~~ x la S s P~ -1~ ~ ~a a~
x ~X o ~ --O ~~ ~ N ~; S.l O
_0-,1 u~ ora ~ C _ ~ Q ~1 0 a)alC ~ r~ r ~ C
V~ Q _~ X O ~a) C ~ ~ ~ 3 , O ~~5 ~ o ~ O ~ o S ~ X O X ~ ~, ~J ~ C aJ
~ ~ 0 0 ~ o 0 ~ ~ ~a ~ ~
^ ~q o ~q la ~:--r ~ S 0~ u~ X ,~
o u~ la o ~ v u7 a -~ x ~ J~ a ~ a~ ~ ~a C ~ ~ a ~o ~a o ~ ~ J~ O ~ C
~ ~ I ~ ~ U~ C ~1 -I ~~ o C ~ la ~ ~ ~ ~_ s~ C o ~n o ~ ~a 0 O ~ o rl a~ (a aJ ~ ~I c ~1 s æ ~ ~ a o c~
Claims (8)
1. A silicone rubber composition to be used for drive shaft seals characterized by (i) 100 parts by weight of an organopolysiloxane gum having the average unit formula where each R represents a monovalent hydrocarbon radical and a has a value of 1.98 to 2.02, (ii) 5 to 100 parts by weight of a reinforcing silica filler, (iii) 5 to 100 parts by weight of diatomaceous earth, (iv) 0.1 to 10 parts by weight of an organohydrogenpoly-siloxane having the average unit formula where R is defined above, b has a value of 1 to 2, c has a value of 0.1 to 1.2, and the sum of b + c has a value of 1.8 to 2.2, said organohydrogenpolysiloxane having at least three silicon-bonded hydrogen atoms per molecule, and (v) 0.1 to 10 parts by weight of an organic peroxide.
2. The composition according to claim 1 in which c has a value of 0.1 to 1.
3. The composition according to claim 2 in which the reinforcing silica filler of (ii) is present in an amount of 20 to 70 parts by weight and the diatomaceous earth of (iii) is present in an amount of 20 to 90 parts by weight.
4. The composition according to claim 3 in which each R in (i) is selected from the methyl and vinyl and R in (iv) is methyl.
5. The composition according to claim 3 in which each R in (i) is selected from methyl, phenyl and vinyl and R
in (iv) is methyl.
in (iv) is methyl.
6. The composition according to claim 4 in which the organohydrogenpolysiloxy of (iv) is a polymer consisting of trimethylsiloxy endblocking units, dimethylsiloxane units and methylhydrogensiloxane units.
7. The composition according to claim 5 in which the organohydrogenpolysiloxane of (iv) is methylhydrogen-cyclotetrasiloxane.
8. A drive shaft seal manufactured from a heat vulcanized silicone rubber which had an unvulcanized composition characterized by (i) 100 parts by weight of an organopolysiloxane gum having the average unit formula where each R represents a monovalent hydrocarbon radical and a has a value of 1.98 to 2.02, (ii) 5 to 100 parts by weight of a reinforcing silica filler, (iii) 5 to 100 parts by weight of diatomaceous earth, (iv) 0.1 to 10 parts by weight of an organohydrogenpoly-siloxane having the average unit formula where R is defined above, b has a value of 1 to 2, c has a value of 0.1 to 1.2, and the sum of b + c has a value of 1.8 to 2.2, said organohydrogenpolysiloxane having at least three silicon-bonded hydrogen atoms per molecule, and (v) 0.1 to 10 parts by weight of an organic peroxide.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11840779A JPS5643351A (en) | 1979-09-14 | 1979-09-14 | Silicone rubber composition for sealing shaft |
| JP118407/79 | 1979-09-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1162687A true CA1162687A (en) | 1984-02-21 |
Family
ID=14735874
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000360008A Expired CA1162687A (en) | 1979-09-14 | 1980-09-10 | Silicone rubber composition for drive shaft seals |
Country Status (11)
| Country | Link |
|---|---|
| JP (1) | JPS5643351A (en) |
| AU (1) | AU535241B2 (en) |
| BE (1) | BE885210A (en) |
| BR (1) | BR8005897A (en) |
| CA (1) | CA1162687A (en) |
| DE (1) | DE3034232A1 (en) |
| FR (1) | FR2464976A1 (en) |
| GB (1) | GB2060667B (en) |
| IT (1) | IT1141044B (en) |
| SE (1) | SE8006416L (en) |
| SU (1) | SU978734A3 (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1984000034A1 (en) * | 1982-06-15 | 1984-01-05 | Toray Silicone Co | Composition for forming releasable film |
| DE3243194A1 (en) * | 1982-11-23 | 1984-05-24 | Degussa Ag, 6000 Frankfurt | METHOD FOR PRODUCING SILICONE RUBBER VOLCANISATES |
| FR2557121B1 (en) * | 1983-12-21 | 1986-10-10 | Rhone Poulenc Spec Chim | HOT VULCANIZABLE ORGANOPOLYSILOXANIC ELASTOMERIC COMPOSITIONS WITH IMPROVED PHYSICAL CHARACTERISTICS |
| US4774281A (en) * | 1987-09-04 | 1988-09-27 | Dow Corning Corporation | Low compression set silicone rubber |
| US5380770A (en) * | 1992-04-09 | 1995-01-10 | General Electric Company | Heat cured silicone rubber compositions containing a potassium aluminosilicate filler which provides resistance to hydrocarbon oils and adjustable shrinkage |
| KR20010069668A (en) * | 2001-04-26 | 2001-07-25 | 이명수 | a composition seal for rotation |
| JP4520159B2 (en) * | 2004-01-07 | 2010-08-04 | 信越化学工業株式会社 | Silicone rubber composition |
| US20100225067A1 (en) * | 2009-03-06 | 2010-09-09 | Gm Global Technology Operations, Inc. | Coated ring seal |
| JP6696586B2 (en) * | 2016-11-17 | 2020-05-20 | 信越化学工業株式会社 | Addition-curable liquid silicone rubber composition for automobile oil filter seal member and automobile oil filter seal member |
| RU2720195C2 (en) * | 2018-08-09 | 2020-04-27 | Общество с ограниченной ответственностью "Изотроп" | Heat-conducting compound |
| RU2720194C2 (en) * | 2018-08-09 | 2020-04-27 | Общество с ограниченной ответственностью "Изотроп" | Composite heat-conducting material |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3865778A (en) * | 1974-02-07 | 1975-02-11 | Gen Electric | Heat vulcanizable silicone rubber compositions resistant to oil degradation |
| JPS5952671B2 (en) * | 1976-09-27 | 1984-12-20 | ト−レ・シリコ−ン株式会社 | Heat-curable silicone rubber composition |
| JPS5388055A (en) * | 1977-01-13 | 1978-08-03 | Toray Silicone Co Ltd | Silicone rubber composition for shaft sealing |
| JPS6039094B2 (en) * | 1977-09-26 | 1985-09-04 | 東芝シリコ−ン株式会社 | Heat-curable silicone rubber composition |
-
1979
- 1979-09-14 JP JP11840779A patent/JPS5643351A/en active Granted
-
1980
- 1980-09-10 GB GB8029205A patent/GB2060667B/en not_active Expired
- 1980-09-10 CA CA000360008A patent/CA1162687A/en not_active Expired
- 1980-09-11 DE DE19803034232 patent/DE3034232A1/en active Granted
- 1980-09-12 BE BE0/202083A patent/BE885210A/en not_active IP Right Cessation
- 1980-09-12 SU SU802980757A patent/SU978734A3/en active
- 1980-09-12 FR FR8019715A patent/FR2464976A1/en active Granted
- 1980-09-12 SE SE8006416A patent/SE8006416L/en unknown
- 1980-09-12 IT IT24633/80A patent/IT1141044B/en active
- 1980-09-12 AU AU62370/80A patent/AU535241B2/en not_active Ceased
- 1980-09-15 BR BR8005897A patent/BR8005897A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| FR2464976A1 (en) | 1981-03-20 |
| SU978734A3 (en) | 1982-11-30 |
| GB2060667B (en) | 1983-10-19 |
| IT1141044B (en) | 1986-10-01 |
| IT8024633A0 (en) | 1980-09-12 |
| JPS623182B2 (en) | 1987-01-23 |
| AU6237080A (en) | 1981-03-19 |
| GB2060667A (en) | 1981-05-07 |
| SE8006416L (en) | 1981-04-30 |
| JPS5643351A (en) | 1981-04-22 |
| BE885210A (en) | 1981-03-12 |
| FR2464976B1 (en) | 1983-08-05 |
| AU535241B2 (en) | 1984-03-08 |
| DE3034232A1 (en) | 1981-04-02 |
| DE3034232C2 (en) | 1991-04-18 |
| BR8005897A (en) | 1981-03-31 |
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