CA2314264A1 - Addition-crosslinking silicone rubber blends, a process for their preparation and their use - Google Patents
Addition-crosslinking silicone rubber blends, a process for their preparation and their use Download PDFInfo
- Publication number
- CA2314264A1 CA2314264A1 CA002314264A CA2314264A CA2314264A1 CA 2314264 A1 CA2314264 A1 CA 2314264A1 CA 002314264 A CA002314264 A CA 002314264A CA 2314264 A CA2314264 A CA 2314264A CA 2314264 A1 CA2314264 A1 CA 2314264A1
- Authority
- CA
- Canada
- Prior art keywords
- weight
- addition
- silicone rubber
- optionally
- crosslinking silicone
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- 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
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2666/00—Composition of polymers characterized by a further compound in the blend, being organic macromolecular compounds, natural resins, waxes or and bituminous materials, non-macromolecular organic substances, inorganic substances or characterized by their function in the composition
- C08L2666/54—Inorganic substances
Landscapes
- 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)
- Processes Of Treating Macromolecular Substances (AREA)
Abstract
The invention relates to addition cross-linking silicone rubbers, a method for their production and their use.
Description
Le A 32 532 Addition-crosslinkin~ silicone rubber blends, a process for their preparation and ' their use The present invention relates to addition-crosslinking silicone rubbers, a process for their preparation and their use.
Addition-crosslinking silicone rubbers are distinguished by a broad range of use. This also includes, for example, use as high-voltage insulators, arresters, etc.
For this field of use, it is necessary for the organopolysiloxane elastomers to have high arc resistance and high creep resistance in combination with good mechanical properties.
It is known that the arc resistance and creep resistance are improved by the addition of aluminum dioxides and/or aluminum hydroxides but the mechanical properties are relatively poor. In addition, these materials cannot be processed on injection molding machines, owing to the high viscosity.
DE-A-3 831 478 discloses the use of addition-crosslinking silicone elastomers which may contain titanium dioxide and zinc oxide in addition to the extender fillers described above. These materials may be crosslinked under platinum catalysis but they have the disadvantage that they do not have a long shelf life in the uncrosslinked state. DE-A-3 048 207 furthermore discloses flameproof materials which also contain magnesium oxide and optionally further additives, such as, for example, Ti02, in addition to hydrated alumina.
However, these materials disadvantageously have a short shelf life and too low a creep resistance.
It was therefore the object of the present invention to provide addition-crosslinking polysiloxane materials which have creep resistance and arc resistance, do not have the disadvantages of the prior art and can be processed by the injection molding technique.
It has now been found that addition-crosslinking organopolysiloxane materials which, in addition to oxidic aluminum compounds, also contain zinc oxide and optionally titanium dioxide have the desired property profile.
The invention therefore relates to addition-crosslinking silicone rubber blends essentially consisting of Le A 32 532 (a) 20 to 40% by weight of at least one linear or branched organopolysiloxane containing alkenyl groups and having a content of 0.0002 to 5% by weight of alkenyl groups with a viscosity of 0.1 to 1000 Pas at 25°C, (b) at least one hydrogensiloxane having at least 3 SiH functions per molecule in an amount such that the molar ratio of SiH groups to the total amount of Si-bonded alkenyl groups is at least 2.0:1, (c) 0.01 to 250 ppm of at least one Pt catalyst and optionally an inhibitor, (d) 35-55% by weight of aluminum hydroxide, alumina and/or mixed oxides/hydroxides thereof, (e) 5 to 25% by weight of at least one, optionally surface-modified filler having a specific surface area of from 150 to 500 m2/g (fj 1 to 5% by weight of at least one metal oxide of zinc having a BET surface area of 30 to 70 m2/g, optionally in combination with 0 to 5% by weight of at least one metal oxide of titanium, having a BET surface area of 35 to 65 m2/g and optionally (g) further auxiliaries, the sum of all components being 100% by weight.
The term organopolysiloxane (a) includes all polysiloxanes used to date in organopolysiloxane materials. It is preferably a siloxane comprising units of the general formula (I) (R)ySiO~a-y>iz in which R denotes a monovalent aliphatic radical having 1 to 8 carbon atoms and an alkyl radical having 2 to 8 carbon atoms, y is 1.95 to 2.01, and which contains at least 0.0002 to 5% by weight of alkenyl groups.
Le A 32 532 Preferably, (a) is dimethylvinylsilyloxy-terminated.
In a preferred embodiment of the invention, the organopolysiloxanes (a) according to the invention have viscosities of 0.01 to 1000 Pas, very particularly preferably 10 to 80 Pas.
The viscosities are determined according to DIN 53 019 at 20°C.
In the context of the invention, hydrogensiloxanes (b) are preferably linear, cyclic or branched organopolysiloxanes comprising units of the general formula (II) (Ri)W(H)ZSi0~4_W_Z~i2 (II), in which R1 is a monovalent aliphatic radical having 1 to 8 carbon atoms, w is0,l,2or3, z is 0, 1 or 2 and the sum w+z is 0, 1, 2 or 3, with the proviso that on average at least 3, preferably 10 to 20, Si-bonded hydrogen atoms are present per molecule.
The hydrogensiloxanes (b) preferably have a viscosity of 0.03 to 1 Pas.
The hydrogensiloxanes (b) may additionally contain organopolysiloxanes whose number of SiH groups is less than 3.
Catalysts (c) for the crosslinking reaction are preferably Pt (0) complexes with alkenyl siloxanes as ligands in catalytic amounts of 0.01 to 250 ppm of Pt.
In the context of the invention, inhibitors are all customary compounds which have been used to date for this purpose. Examples of such preferred inhibitors are e.g.
1,3-divinyl-tetramethyldisiloxane, 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasilox-ane, 2-methylbutin-2-of or 1-ethinylcyclohexanol in amounts of 50 to 10,000 ppm.
Le A 32 532 Aluminum hydroxide, alumina and/or the mixed oxides/hydroxides thereof, such as, for example, Al0(OH), are preferably those compounds which have a BET surface area of 3 to 6 m2/g, measured by means of N2 absorption.
In the context of the invention, fillers (e) are preferably reinforcing fillers, such as, for example, pyrogenic silica having a BET surface area between 50 and 400 m2/g, measured by means of N2 absorption, which may also be surface-treated, and/or extender fillers, such as, for example, quartz powder.
The surface treatment may also be carned out in situ by the addition of silazanes, such as hexamethylsilazane and/or divinyltetramethyldisilazane, and vinylalkoxysilanes, such as, for example, vinyltrimethoxysilane, and water or other customary filler loading compositions.
1 S Metal oxides (f) of zinc are preferably those compounds which have a BET
surface area of 45 to 55 m2/g, and oxides of titanium which have a BET surface area of 45 to 55 m2/g, measured by means of N2 absorption.
In a further preferred embodiment of the invention, the blend contains further auxiliaries (g), such as color-imparting, inorganic pigments, such as iron oxides or cobalt spinets.
The invention also relates to a process for the preparation of the addition-crosslinking silicone rubber blends according to the invention, according to which 1. at least one organopolysiloxane (a), catalyst (c), aluminum hydroxide (d) and metal oxides (f), optionally fillers (e) and/or auxiliaries (g) are mixed and 2, at least one organopolysiloxane (a), at least one hydrogensiloxane (b) and optionally fillers (e) and aluminum hydroxide (d) auxiliaries (g) and/or inhibitor (c) and metal oxides (f) are mixed as a separate mixture, and these two mixtures are combined only in the injection molding machine [lacuna] in an upstream mixing head with subsequent static mixer.
Mixing is preferably effected by means of mixers suitable for high-viscosity materials, such as, for example, kneaders, dissolvers or planetary mixers.
In one embodiment of the process according to the invention, the filler is rendered hydrophobic, the imparting of hydrophobic properties preferably being effected in situ by the addition of hexamethyldisilazane and/or divinyltetramethyldisilazane and water.
In the in situ imparting of hydrophobic properties, preferably organopolysiloxane (a), Le A 32 532 filler (e) and aluminum hydroxide (d) and the water repellent, preferably ' hexamethyldisilazane and/or divinyltetramethyldisilazane, are stirred, preferably at temperatures of 90-100°C for at least 20 minutes in a mixing unit suitable for high-viscosity materials, such as, for example, a kneader, dissolver or planetary mixer, and then freed at Temperatures 150-160 C from excess loading compositions and water, initially at atmospheric pressure and then in vacuo at a pressure of 100 to 20 mbar. The further components (b and f) or (c), (f) and optionally (g) are then mixed in over 10 to 30 minutes.
The invention also relates to the use of the addition-crosslinking silicone rubber blends according to the invention for the preparation of silicone elastomers having creep resistance and arc resistance.
The following Examples, in which all parts denote parts by weight, illustrate the invention but without restricting it.
Le A 32 532 Examples Example 1 In a dissolves having a planetary gear, 75 parts by weight of a vinyl-terminated polydimethylsiloxane mixture having an average viscosity of 40 Pa.s at 25°C (a) were mixed with 10 parts by weight of hexamethyldisilazane and 5 parts by weight of water and then stirred with 31 parts by weight of pyrogenically prepared silica having a specific surface area of 300 m2/g according to BET (e), 110 parts by weight of low-sodium aluminum trihydroxide (d) and 2 parts by weight of pyrogenically prepared titanium dioxide (fj to give a homogeneous material. The mixture was first heated to 100°C and stirred for 2 hours in the closed dissolves and then freed from water and excess silazane at 160°C in vacuo.
After the material had been cooled to 90°C, 33 parts by weight of a vinyl-terminated polydimethylsiloxane mixture having an average viscosity of 5 Pa.s at 25°C (a) and 0.05 parts by weight of a platinum catalyst in the form of a complex of chloroplatinic acid with symmetrical divinyltetramethyldisiloxane and containing 0.15% of platinum (c) were added. The material thus obtained is referred to as component A
below.
In a dissolves having a planetary gear, 75 parts by weight of a vinyl-terminated polydimethylsiloxane mixture having an average viscosity of 40 Pa.s at 25°C (a) were mixed with 10 parts by weight of hexamethyldisilazane and 5 parts by weight of water and then stirred with 32 parts by weight of pyrogenically prepared silica having a specific surface area of 300 m2/g according to BET (e), 110 parts by weight of low-sodium aluminum trihydroxide (d) and 2 parts by weight of pyrogenically prepared titanium dioxide (f) to give a homogeneous material. The mixture was first heated to 100°C and stirred for 2 hours in the closed dissolves and then freed from water and excess silazane at 160°C in vacuo.
After the material had been cooled to 90°C, 22 parts by weight of a vinyl-terminated polydimethylsiloxane mixture having an average viscosity of 10 Pa.s at 25°C (a), 4 parts by weight of activated zinc oxide (f), 22 parts by weight of a mixture of trimethylsilyl-terminated polyorganosiloxane crosslinking agent having on average 8 methylhydrogensiloxane units and 100 dimethylsiloxane units per molecule (b) and about 0.2 parts by weight of ethinylcyclohexanol as inhibitor (c) were added.
The material thus obtained is referred to as component B below.
50 parts of each of the components A and B described above were stirred together and Le A 32 532 _7_ sheets having a thickness of 2 or 6 mm were produced by vulcanization at 175°C for minutes. The sheets were then heated for 4 hours at 200°C in a forced-circulation oven. For all vulcanized products thus produced, the reactivity, the mechanical properties and the arc resistance according to DIN 57 441 and creep resistance 5 according to IEC Publ. 587 were tested.
Table 1 Reactivity t60 after 1 day 3.7 sec Reactivity t60 after 21 days 3.9 sec Reactivity t60 after 183 days 4.2 sec Tensile strengthDIN 53 504 S2 4.0 N/mm2 Elongation DIN 53 504 S2 600%
Shore A hardnessDIN 53 505 40 Arc resistance DIN 57 441 HL 2 Creep resistanceIEC Publ. 587 1 A 3.5
Addition-crosslinking silicone rubbers are distinguished by a broad range of use. This also includes, for example, use as high-voltage insulators, arresters, etc.
For this field of use, it is necessary for the organopolysiloxane elastomers to have high arc resistance and high creep resistance in combination with good mechanical properties.
It is known that the arc resistance and creep resistance are improved by the addition of aluminum dioxides and/or aluminum hydroxides but the mechanical properties are relatively poor. In addition, these materials cannot be processed on injection molding machines, owing to the high viscosity.
DE-A-3 831 478 discloses the use of addition-crosslinking silicone elastomers which may contain titanium dioxide and zinc oxide in addition to the extender fillers described above. These materials may be crosslinked under platinum catalysis but they have the disadvantage that they do not have a long shelf life in the uncrosslinked state. DE-A-3 048 207 furthermore discloses flameproof materials which also contain magnesium oxide and optionally further additives, such as, for example, Ti02, in addition to hydrated alumina.
However, these materials disadvantageously have a short shelf life and too low a creep resistance.
It was therefore the object of the present invention to provide addition-crosslinking polysiloxane materials which have creep resistance and arc resistance, do not have the disadvantages of the prior art and can be processed by the injection molding technique.
It has now been found that addition-crosslinking organopolysiloxane materials which, in addition to oxidic aluminum compounds, also contain zinc oxide and optionally titanium dioxide have the desired property profile.
The invention therefore relates to addition-crosslinking silicone rubber blends essentially consisting of Le A 32 532 (a) 20 to 40% by weight of at least one linear or branched organopolysiloxane containing alkenyl groups and having a content of 0.0002 to 5% by weight of alkenyl groups with a viscosity of 0.1 to 1000 Pas at 25°C, (b) at least one hydrogensiloxane having at least 3 SiH functions per molecule in an amount such that the molar ratio of SiH groups to the total amount of Si-bonded alkenyl groups is at least 2.0:1, (c) 0.01 to 250 ppm of at least one Pt catalyst and optionally an inhibitor, (d) 35-55% by weight of aluminum hydroxide, alumina and/or mixed oxides/hydroxides thereof, (e) 5 to 25% by weight of at least one, optionally surface-modified filler having a specific surface area of from 150 to 500 m2/g (fj 1 to 5% by weight of at least one metal oxide of zinc having a BET surface area of 30 to 70 m2/g, optionally in combination with 0 to 5% by weight of at least one metal oxide of titanium, having a BET surface area of 35 to 65 m2/g and optionally (g) further auxiliaries, the sum of all components being 100% by weight.
The term organopolysiloxane (a) includes all polysiloxanes used to date in organopolysiloxane materials. It is preferably a siloxane comprising units of the general formula (I) (R)ySiO~a-y>iz in which R denotes a monovalent aliphatic radical having 1 to 8 carbon atoms and an alkyl radical having 2 to 8 carbon atoms, y is 1.95 to 2.01, and which contains at least 0.0002 to 5% by weight of alkenyl groups.
Le A 32 532 Preferably, (a) is dimethylvinylsilyloxy-terminated.
In a preferred embodiment of the invention, the organopolysiloxanes (a) according to the invention have viscosities of 0.01 to 1000 Pas, very particularly preferably 10 to 80 Pas.
The viscosities are determined according to DIN 53 019 at 20°C.
In the context of the invention, hydrogensiloxanes (b) are preferably linear, cyclic or branched organopolysiloxanes comprising units of the general formula (II) (Ri)W(H)ZSi0~4_W_Z~i2 (II), in which R1 is a monovalent aliphatic radical having 1 to 8 carbon atoms, w is0,l,2or3, z is 0, 1 or 2 and the sum w+z is 0, 1, 2 or 3, with the proviso that on average at least 3, preferably 10 to 20, Si-bonded hydrogen atoms are present per molecule.
The hydrogensiloxanes (b) preferably have a viscosity of 0.03 to 1 Pas.
The hydrogensiloxanes (b) may additionally contain organopolysiloxanes whose number of SiH groups is less than 3.
Catalysts (c) for the crosslinking reaction are preferably Pt (0) complexes with alkenyl siloxanes as ligands in catalytic amounts of 0.01 to 250 ppm of Pt.
In the context of the invention, inhibitors are all customary compounds which have been used to date for this purpose. Examples of such preferred inhibitors are e.g.
1,3-divinyl-tetramethyldisiloxane, 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasilox-ane, 2-methylbutin-2-of or 1-ethinylcyclohexanol in amounts of 50 to 10,000 ppm.
Le A 32 532 Aluminum hydroxide, alumina and/or the mixed oxides/hydroxides thereof, such as, for example, Al0(OH), are preferably those compounds which have a BET surface area of 3 to 6 m2/g, measured by means of N2 absorption.
In the context of the invention, fillers (e) are preferably reinforcing fillers, such as, for example, pyrogenic silica having a BET surface area between 50 and 400 m2/g, measured by means of N2 absorption, which may also be surface-treated, and/or extender fillers, such as, for example, quartz powder.
The surface treatment may also be carned out in situ by the addition of silazanes, such as hexamethylsilazane and/or divinyltetramethyldisilazane, and vinylalkoxysilanes, such as, for example, vinyltrimethoxysilane, and water or other customary filler loading compositions.
1 S Metal oxides (f) of zinc are preferably those compounds which have a BET
surface area of 45 to 55 m2/g, and oxides of titanium which have a BET surface area of 45 to 55 m2/g, measured by means of N2 absorption.
In a further preferred embodiment of the invention, the blend contains further auxiliaries (g), such as color-imparting, inorganic pigments, such as iron oxides or cobalt spinets.
The invention also relates to a process for the preparation of the addition-crosslinking silicone rubber blends according to the invention, according to which 1. at least one organopolysiloxane (a), catalyst (c), aluminum hydroxide (d) and metal oxides (f), optionally fillers (e) and/or auxiliaries (g) are mixed and 2, at least one organopolysiloxane (a), at least one hydrogensiloxane (b) and optionally fillers (e) and aluminum hydroxide (d) auxiliaries (g) and/or inhibitor (c) and metal oxides (f) are mixed as a separate mixture, and these two mixtures are combined only in the injection molding machine [lacuna] in an upstream mixing head with subsequent static mixer.
Mixing is preferably effected by means of mixers suitable for high-viscosity materials, such as, for example, kneaders, dissolvers or planetary mixers.
In one embodiment of the process according to the invention, the filler is rendered hydrophobic, the imparting of hydrophobic properties preferably being effected in situ by the addition of hexamethyldisilazane and/or divinyltetramethyldisilazane and water.
In the in situ imparting of hydrophobic properties, preferably organopolysiloxane (a), Le A 32 532 filler (e) and aluminum hydroxide (d) and the water repellent, preferably ' hexamethyldisilazane and/or divinyltetramethyldisilazane, are stirred, preferably at temperatures of 90-100°C for at least 20 minutes in a mixing unit suitable for high-viscosity materials, such as, for example, a kneader, dissolver or planetary mixer, and then freed at Temperatures 150-160 C from excess loading compositions and water, initially at atmospheric pressure and then in vacuo at a pressure of 100 to 20 mbar. The further components (b and f) or (c), (f) and optionally (g) are then mixed in over 10 to 30 minutes.
The invention also relates to the use of the addition-crosslinking silicone rubber blends according to the invention for the preparation of silicone elastomers having creep resistance and arc resistance.
The following Examples, in which all parts denote parts by weight, illustrate the invention but without restricting it.
Le A 32 532 Examples Example 1 In a dissolves having a planetary gear, 75 parts by weight of a vinyl-terminated polydimethylsiloxane mixture having an average viscosity of 40 Pa.s at 25°C (a) were mixed with 10 parts by weight of hexamethyldisilazane and 5 parts by weight of water and then stirred with 31 parts by weight of pyrogenically prepared silica having a specific surface area of 300 m2/g according to BET (e), 110 parts by weight of low-sodium aluminum trihydroxide (d) and 2 parts by weight of pyrogenically prepared titanium dioxide (fj to give a homogeneous material. The mixture was first heated to 100°C and stirred for 2 hours in the closed dissolves and then freed from water and excess silazane at 160°C in vacuo.
After the material had been cooled to 90°C, 33 parts by weight of a vinyl-terminated polydimethylsiloxane mixture having an average viscosity of 5 Pa.s at 25°C (a) and 0.05 parts by weight of a platinum catalyst in the form of a complex of chloroplatinic acid with symmetrical divinyltetramethyldisiloxane and containing 0.15% of platinum (c) were added. The material thus obtained is referred to as component A
below.
In a dissolves having a planetary gear, 75 parts by weight of a vinyl-terminated polydimethylsiloxane mixture having an average viscosity of 40 Pa.s at 25°C (a) were mixed with 10 parts by weight of hexamethyldisilazane and 5 parts by weight of water and then stirred with 32 parts by weight of pyrogenically prepared silica having a specific surface area of 300 m2/g according to BET (e), 110 parts by weight of low-sodium aluminum trihydroxide (d) and 2 parts by weight of pyrogenically prepared titanium dioxide (f) to give a homogeneous material. The mixture was first heated to 100°C and stirred for 2 hours in the closed dissolves and then freed from water and excess silazane at 160°C in vacuo.
After the material had been cooled to 90°C, 22 parts by weight of a vinyl-terminated polydimethylsiloxane mixture having an average viscosity of 10 Pa.s at 25°C (a), 4 parts by weight of activated zinc oxide (f), 22 parts by weight of a mixture of trimethylsilyl-terminated polyorganosiloxane crosslinking agent having on average 8 methylhydrogensiloxane units and 100 dimethylsiloxane units per molecule (b) and about 0.2 parts by weight of ethinylcyclohexanol as inhibitor (c) were added.
The material thus obtained is referred to as component B below.
50 parts of each of the components A and B described above were stirred together and Le A 32 532 _7_ sheets having a thickness of 2 or 6 mm were produced by vulcanization at 175°C for minutes. The sheets were then heated for 4 hours at 200°C in a forced-circulation oven. For all vulcanized products thus produced, the reactivity, the mechanical properties and the arc resistance according to DIN 57 441 and creep resistance 5 according to IEC Publ. 587 were tested.
Table 1 Reactivity t60 after 1 day 3.7 sec Reactivity t60 after 21 days 3.9 sec Reactivity t60 after 183 days 4.2 sec Tensile strengthDIN 53 504 S2 4.0 N/mm2 Elongation DIN 53 504 S2 600%
Shore A hardnessDIN 53 505 40 Arc resistance DIN 57 441 HL 2 Creep resistanceIEC Publ. 587 1 A 3.5
Claims (6)
1. Addition-crosslinking silicone rubber blends essentially consisting of (a) 20 to 40% by weight of at least one linear or branched organopolysiloxane containing alkenyl groups and having a content of 0.0002 to 3% by weight of alkenyl groups with a viscosity of 0.1 to 1000 Pas at 25°C, (b) at least one hydrogensiloxane having at least 3 SiH functions per molecule in an amount such that the molar ratio of SiH groups to the total amount of Si-bonded alkenyl groups is at least 2.0:1, (c) 0.01 to 250 ppm of at least one Pt catalyst and optionally an inhibitor, (d) 35-55% by weight of aluminum hydroxide, alumina and/or mixed oxides/hydroxides thereof, (e) 5 to 25% by weight of at least one, optionally surface-modified filler having a specific surface area of from 150 to 500 m2/g (f) 1 to 5% by weight of at least one metal oxide of zinc having a BET
surface area of 30 to 70 m2/g, optionally in combination with 0 to 5% by weight of at least one metal oxide of titanium, having a BET surface area of 35 to 65 m2/g and optionally (g) further auxiliaries, the sum of all components being 100% by weight.
surface area of 30 to 70 m2/g, optionally in combination with 0 to 5% by weight of at least one metal oxide of titanium, having a BET surface area of 35 to 65 m2/g and optionally (g) further auxiliaries, the sum of all components being 100% by weight.
2. Addition-crosslinking silicone rubber blends according to Claim 1, characterized in that the organopolysiloxane (a) is a siloxane comprising units of the general formula (1) (R)ySiO(4-y)/2 (I), in which R denotes a monohydric aliphatic radical having 1 to 8 carbon atoms and an alkenyl radical having 2 to 8 carbon atoms, y is 1.95 to 2.01, and which contains at least 0.0002 to 5% by weight of alkenyl groups.
3. Addition-crosslinking silicone rubber blends according to Claim 1 or 2, characterized in that the hydrogensiloxanes (b) are siloxanes comprising units of the general formula (II) (R1)W(H)zSiO(4-w-z)/2 (II), in which R1 is a monovalent aliphatic radical having 1 to 8 carbon atoms, w is 0, 1, 2 or 3, z is 0, 1 or 2 and w+z is 0, 1, 2 or 3, with the proviso that on average at least 3 Si-bonded hydrogen atoms are present per molecule.
4. Process for the preparation of addition-crosslinking silicone rubber blends according to one or more of Claims 1 to 3, characterized in that 1. at least one organopolysiloxane (a), catalyst (c), aluminum hydroxide (d) and metal oxide (f), optionally fillers (e) and/or auxiliaries (g) are mixed and 2. at least one organopolysiloxane (a), at least one hydrogensiloxane (b) and optionally fillers (e) and aluminum hydroxide (d) auxiliaries (g) and/or inhibitor (c) and metal oxides (f) are mixed as a separate mixture, and these two mixtures are combined only in the injection molding machine or in an upstream mixing head with subsequent static mixer.
5. Process according to Claim 4, characterized in that a filler (e) and aluminum hydroxide (d) are rendered hydrophobic in situ by addition of hexamethyldisilazane and/or divinyltetramethyldisilazane and water.
6. Use of the addition-crosslinking silicone rubber blend according to one or more of Claims 1 to 3 for the preparation of silicone elastomers having creep usistance and arc resistanc.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/EP1998/006445 WO2000022047A1 (en) | 1997-09-16 | 1998-10-12 | Addition cross-linking silicone rubber mixtures, a method for their production and their use |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2314264A1 true CA2314264A1 (en) | 2000-04-20 |
Family
ID=8167093
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002314264A Abandoned CA2314264A1 (en) | 1998-10-12 | 1998-10-12 | Addition-crosslinking silicone rubber blends, a process for their preparation and their use |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JP2002527561A (en) |
| KR (1) | KR20010033007A (en) |
| AT (1) | ATE211158T1 (en) |
| CA (1) | CA2314264A1 (en) |
| DE (1) | DE59802583D1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7385000B2 (en) | 2004-10-14 | 2008-06-10 | Wacker Chemie Ag | Silicone rubber composition having improved storage stability |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20040076435A (en) * | 2003-02-25 | 2004-09-01 | 주식회사 금강고려화학 | Self-extinguishing additive RTV silicone rubber composition |
| DE102004050129A1 (en) * | 2004-10-14 | 2006-04-20 | Wacker Chemie Ag | Silicone rubber composition containing untreated aluminum hydroxide as filler |
| CN101168620B (en) * | 2007-09-04 | 2012-07-25 | 东莞兆舜有机硅新材料科技有限公司 | Heat-conducting anti-flaming liquid silicon rubber and preparation method thereof |
| DE102007055844A1 (en) * | 2007-12-17 | 2009-06-25 | Wacker Chemie Ag | Crosslinkable silicone coating compositions |
| CN104884534B (en) * | 2012-12-27 | 2018-03-30 | 道康宁公司 | For the product for forming the composition of the product with excellent reflection rate and flame-retardant nature and being formed by it |
| WO2022071707A1 (en) * | 2020-09-29 | 2022-04-07 | 주식회사 엘지에너지솔루션 | Curable composition and two-liquid-type curable composition |
-
1998
- 1998-10-12 DE DE59802583T patent/DE59802583D1/en not_active Expired - Lifetime
- 1998-10-12 JP JP2000575945A patent/JP2002527561A/en active Pending
- 1998-10-12 AT AT98955431T patent/ATE211158T1/en not_active IP Right Cessation
- 1998-10-12 CA CA002314264A patent/CA2314264A1/en not_active Abandoned
- 1998-10-12 KR KR1020007006359A patent/KR20010033007A/en not_active Application Discontinuation
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7385000B2 (en) | 2004-10-14 | 2008-06-10 | Wacker Chemie Ag | Silicone rubber composition having improved storage stability |
Also Published As
| Publication number | Publication date |
|---|---|
| KR20010033007A (en) | 2001-04-25 |
| ATE211158T1 (en) | 2002-01-15 |
| DE59802583D1 (en) | 2002-01-31 |
| JP2002527561A (en) | 2002-08-27 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR100680930B1 (en) | Silicone rubber composition having improved keeping qualities | |
| KR101455123B1 (en) | Thermosetting silicone rubber composition | |
| JP4209608B2 (en) | Room temperature curable silicone rubber composition | |
| WO2016199742A1 (en) | Addition-curable silicone rubber composition and cured product | |
| JP6947124B2 (en) | Curable Silicone Gel Composition and Silicone Gel Cured Product | |
| EP3533838B1 (en) | Heat-resistant millable silicone rubber composition | |
| KR20110018874A (en) | Silicone rubber compositions | |
| CA2314264A1 (en) | Addition-crosslinking silicone rubber blends, a process for their preparation and their use | |
| JP2001164111A (en) | Silicone rubber composition and silicone rubber composition for key pad | |
| JP3977239B2 (en) | Method for producing liquid silicone composition | |
| EP1037946B1 (en) | Addition cross-linking silicone rubber mixtures, a method for their production and their use | |
| US20070066783A1 (en) | Silicone material having outstanding viscosity stability | |
| JP4334632B2 (en) | Silicone rubber composition for polymer insulator and polymer insulator | |
| JP2007180044A (en) | Method of improving high-voltage electrical insulating characteristic of polymer insulator | |
| JP2006001953A (en) | High-hardness addition-curing type liquid silicone rubber composition and method for producing the same | |
| WO2018092490A1 (en) | Addition-curable liquid silicone rubber composition for automobile oil filter sealing member, and automobile oil filter sealing member | |
| JPH0339361A (en) | Preparation of fluorosilicone rubber composition and fluorosilicone rubber | |
| WO2024070556A1 (en) | Millable silicone rubber compound, millable silicone rubber composition, and production method for millable silicone rubber composition | |
| JP4593592B2 (en) | High temperature compression resistant silicone rubber composition | |
| WO2022163365A1 (en) | Oil-bleeding silicone rubber composition | |
| WO2023218904A1 (en) | Millable silicone rubber composition and cured product of same | |
| WO2023008042A1 (en) | Liquid-addition-curable fluorosilicone composition, silicone rubber, and molded article | |
| JP2022132904A (en) | Heat-resistant millable silicone rubber composition | |
| EP4296304A1 (en) | Heat-resistant millable fluorosilicone rubber composition | |
| JP2022131222A (en) | Curable liquid silicone rubber foaming body composition for mechanical forming and manufacturing method of silicone rubber foaming body |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |