EP0043640A1
Expired / Lapsed
EP
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Optically clear silicone compositions curable to elastomers
Assignee: Dow Silicones Corp
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Filing: 1981-04-23
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Granted: —
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Expires: 2001-04-23
Abstract
Abstract Optically clear silicone compositions comprising 100 parts by weight of at least one polydiorganosiloxane and 15 to 120 parts by weight of a hydrophobic reinforcing silica filler wherein substantially all of the surface-treated silica filler particles are sufficiently small in their largest dimensions such that a uniform 2.54 mm thickness of the composition possesses a haze value of less than 4% and a luminous transmittance value of at least 85% according to ASTM D1003-61. The refractive index of the polydiorganosiloxane does not have to be matched with that of the silica filler to obtain optically clear compositions. The haze value of such compositions does not increase by more than 1 % per 2.54 mm thickness when the composition is heated from 23°±2°C to 100°±5°C. Optionally, curing agents and other additives can be present in the compositions. Optically clear cured elastomers useful as lenses or tubing can be prepared from such elastomers. Methods for the preparation of such compositions are also claimed.
Inventors
- 👤 Keith Earl Polmanteer
- 👤 Harry Lee Chapman
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 10:42
CPC Classifications
C; C09; C09C; C09C1/00; C09C1/28; C09C1/30; C09C1/3081; C08; C08G; C08G77/00; C08G77/02; C08K; C08K3/00; C08K3/34; G; G02; G02B; G02B1/00; G02B1/04; C01; C01P; C01P2004/00; C01P2004/01; C01P2004/03; C01P2004/30; C01P2004/32; C01P2004/50; C01P2004/51; C01P2004/60; C01P2004/62; C01P2006/00; C01P2006/10; C01P2006/12; C01P2006/14; C01P2006/60; C01P2006/90
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
466 words
An optically clear composition curable to an elastomer characterized by: (A) 100 parts by weight of at least one polydiorganosiloxane consisting essentially of siloxane units selected from the group consisting of siloxane units of the average unit formula wherein each R radical is selected from the group consisting of alkyl radicals of from 1 to 6 inclusive carbon atoms, cyclohexyl radicals, phenyl radicals, halogenated alkyl radicals of from 1 to 10 inclusive carbon atoms and alkenyl radicals of from 2 to 6 inclusive carbon atoms, each X being selected from the group consisting of hydroxyl radicals, hydrogen radicals and alkoxy radicals of from 1 to 6 inclusive carbon atoms, at least 50 percent of the total amount of R radicals and radicals present in said polydiorganosiloxane being methyl radicals, a having a value of from 0 to 1 inclusive, b having a value of from 1 to 3 inclusive and c having a value of from O.to 1 inclusive, the sum of a + b having a value of from 1 to 3 inclusive, the sum of a + c having a value of from 0 to 1 inclusive, the values of a, b and c being such that the ratio of total R radicals and radicals to total silicon atoms present in said polydiorganosiloxane is in the range of from 1.98/1 to 2.02/1 inclusive, said polydiorganosiloxane having a viscosity of at least 0.1 pascal.seconds at 25°C, and (B) 15 to 120 parts by weight of a hydrophobic reinforcing silica filler consisting essentially of surface-treated silica particles wherein said particles consist essentially of Si0 4/2 units containing a sufficient amount of organosiloxy units chemically bonded to the surface of said particles to render the silica filler hydrophobic, said organosiloxy units being selected from the group consisting of R 3 SiO l/2 units, R 2 SiO units, Oi /2 R 2 SiO(R 2 SiO) d SiR 2 0 1/2 units, XR 2 SiO(R 2 SiO) d SiR 2 O 1/2 units and mixtures thereof where each R and each X are as above defined and d has an average value of from 1 to 12 inclusive, wherein substantially all of said particles of (B) are sufficiently small in their largest dimension such that the mixture of (A) and (B) is an optically clear composition possessing a luminous transmittance value of at least 85% and a haze value of no greater than 4% per .2.54 millimeter thickness of said composition at 23°+2°C according to the procedure set out in ASTM D1003-61 and wherein the haze value of a composition consisting of a mixture of 100 cubic centimeters of (A) at 23°+2°C and 60 grams of (B) does not increase by more than 1% per 2.54 millimeter thickness of said mixture upon heating the mixture from 23°+2°C to 100°+5°C.
Claim 2
Dependent Claim
466 words
An optically clear composition curable to an elastomer characterized by: (A) 100 parts by weight of at least one polydiorganosiloxane consisting essentially of siloxane units selected from the group consisting of siloxane units of the average unit formula wherein each R radical is selected from the group consisting of alkyl radicals of from 1 to 6 inclusive carbon atoms, cyclohexyl radicals, phenyl radicals, halogenated alkyl radicals of from 1 to 10 inclusive carbon atoms and alkenyl radicals of from 2 to 6 inclusive carbon atoms, each X being selected from the group consisting of hydroxyl radicals, hydrogen radicals and alkoxy radicals of from 1 to 6 inclusive carbon atoms, at least 50 percent of the total amount of R radicals and radicals present in said polydiorganosiloxane being methyl radicals, a having a value of from 0 to 1 inclusive, b having a value of from 1 to 3 inclusive and c having a value of from O.to 1 inclusive, the sum of a + b having a value of from 1 to 3 inclusive, the sum of a + c having a value of from 0 to 1 inclusive, the values of a, b and c being such that the ratio of total R radicals and radicals to total silicon atoms present in said polydiorganosiloxane is in the range of from 1.98/1 to 2.02/1 inclusive, said polydiorganosiloxane having a viscosity of at least 0.1 pascal.seconds at 25°C, and (B) 15 to 120 parts by weight of a hydrophobic reinforcing silica filler consisting essentially of surface-treated silica particles wherein said particles consist essentially of Si0 4/2 units containing a sufficient amount of organosiloxy units chemically bonded to the surface of said particles to render the silica filler hydrophobic, said organosiloxy units being selected from the group consisting of R 3 SiO l/2 units, R 2 SiO units, Oi /2 R 2 SiO(R 2 SiO) d SiR 2 0 1/2 units, XR 2 SiO(R 2 SiO) d SiR 2 O 1/2 units and mixtures thereof where each R and each X are as above defined and d has an average value of from 1 to 12 inclusive, wherein substantially all of said particles of (B) are sufficiently small in their largest dimension such that the mixture of (A) and (B) is an optically clear composition possessing a luminous transmittance value of at least 85% and a haze value of no greater than 4% per .2.54 millimeter thickness of said composition at 23°+2°C according to the procedure set out in ASTM D1003-61 and wherein the haze value of a composition consisting of a mixture of 100 cubic centimeters of (A) at 23°+2°C and 60 grams of (B) does not increase by more than 1% per 2.54 millimeter thickness of said mixture upon heating the mixture from 23°+2°C to 100°+5°C.
Claim 3
Dependent Claim
88 words
The composition as claimed in claim 1 wherein (B) is a hydrophobic reinforcing silica filler obtained from the alkaline hydrolysis of Si(OCH 3 ) 4 in the presence of at least 70% of one-half of the stoichiometric amount of water required to completely hydrolyze the theoretical amount of -OCH 3 radicals present in the Si(OCH 3 ) 4 , at least one alcohol selected from the group consisting of methanol, ethanol, n-propanol and isopropanol, at least one basic catalyst, and at least one of said organosilicon hydrophobing compounds.
Claim 4
Dependent Claim
25 words
The composition as claimed in claim 1 wherein each R radical is selected from the group consisting of methyl radicals, vinyl radicals and 3,3,3-trifluoropropyl radicals.
Claim 5
Dependent Claim
50 words
The composition as claimed in claim 1 wherein said (A) is a polydiorganosiloxane gum having a viscosity of at least 10 kilopascal · seconds at 25°C and wherein at least two siloxane units present in sa.id (A) contain vinyl radicals, any X radicals present in said (A) being hydroxyl radicals.
Claim 6
Dependent Claim
143 words
The composition as claimed in claim 1 wherein each R radical present in said polydiorganosiloxane is selected from the group consisting of methyl radicals, vinyl radicals and 3,3,3-trifluoropropyl radicals, wherein at least 7 mole percent of the siloxane units present in said polydiorganosiloxane contain 3,3,3-trifluoropropyl - radicals and no more than 5 mole percent of the siloxane units present in said polydiorganosiloxane contain vinyl radicals, there being no more than one vinyl radical per siloxane unit and no more than one 3,3,3-trifluoropropyl radical per siloxane unit, the mole percent of said siloxane units being based upon the total moles of siloxane units present in said polydiorganosiloxane and wherein said organosiloxy units of (B) consist primarily of organosiloxy units containing one 3,3,3-trifluoropropyl radical per silicon atom, each of the remaining R radicals being selected from the group consisting of methyl radicals and vinyl radicals.
Claim 7
Dependent Claim
107 words
The composition as claimed in claim 2 wherein the method by which the filler is obtained comprises the steps of (I) mixing said water, alcohol and any basic catalyst not provided by the organosilicon hydrophobing compounds together to form a solution, (II) mixing the total amount of said organosilicon hydrophobing compounds into the solution to form a mixture, (III) mixing the Si(OCH 3 ) 4 into the mixture to form a composition containing a silica filler, and (IV) aging the composition for a sufficient amount of time to render the silica filler present in said composition hydrophobic, thereby obtaining a composition containing a hydrophobic reinforcing silica filler.
Claim 8
Dependent Claim
106 words
The composition as claimed in claim 2 wherein the method by which the filler is obtained comprises the steps of (I) mixing said water, alcohol and any basic catalyst not provided by the organosilicon hydrophobing compounds together to form a solution, (II) adding a solution composed of the Si(OCH 3 ) 3 and the total amount of said organosilicon hydrophobing compounds to the solution of step (I) to form a composition containing a silica filler, and (III) aging the composition for a sufficient amount of time to render the silica filler present in said composition hydrophobic, thereby obtaining a composition containing a hydrophobic reinforcing silica filler.
Claim 9
Dependent Claim
17 words
The composition as claimed in claims 1 or 2, which additionally contains at least one curing agent.
Claim 10
Dependent Claim
19 words
An optically clear elastomer which comprises the product formed upon curing the composition of claims 1, 2, or 8.
Claim 11
Independent Claim
389 words
A method for producing an optically clear composition curable to an elastomer characterized by the steps of (I) mixing (A) 100 parts by weight of at least one polydiorganosiloxane consisting essentially of siloxane units selected from the group consisting of siloxane units of the average unit formula wherein each R radical is selected from the group consisting of alkyl radicals of from 1 to 6 inclusive carbon atoms, cyclohexyl radicals, phenyl radicals, halogenated alkyl radicals of from 1 to 10 inclusive carbon atoms and alkenyl radicals of from 2 to 6 inclusive carbon atoms, each X being selected from the group consisting of hydroxyl radicals, hydrogen radicals and alkoxy radicals of from 1 to 6 inclusive carbon atoms, at least 50 percent of the total amount of R radicals and radicals present in said polydiorganosiloxane being methyl radicals, a having a value of from 0 to 1 inclusive, b having a value of from 1 to 3 inclusive and c having a value of from 0 to 1 inclusive, the sum of a + b having a value of from 1 to 3 inclusive, the sum of a + c having a value of from 0 to 1 inclusive, the values of a, b and c being such that the ratio of total R radicals and radicals to total silicon atoms present in said polydiorganosiloxane is in the range of from 1.98/1 to 2.02/1 inclusive, said polydiorganosiloxane having a viscosity of at least 0.1 pascal·seconds at 25°C, and (B) a sufficient amount of a wet, fluid filler composition to provide from 15 to 120 parts by weight per 100 parts by weight of (A) of a hydrophobic reinforcing silica filler consisting essentially of surface-treated silica particles wherein said particles consist essentially of Si0 4/2 units containing a sufficient amount of organosiloxy units chemically bonded to the surface of said particle to render the silica filler hydrophobic, said organosiloxy units being selected from the group consisting of R 3 SiO 1/2 units, R 2 SiO units, O 1 / 2 R 2 SiO(R 2 SiO) d SiR 2 O 1/2 units, XR 2 SiO(R 2 SiO) d SiR 2 O 1/2 units and mixtures thereof where each R and each X are as above and d has an average value of from 1 to 12 inclusive, to form a mixture,
Claim 12
Independent Claim
389 words
A method for producing an optically clear composition curable to an elastomer characterized by the steps of (I) mixing (A) 100 parts by weight of at least one polydiorganosiloxane consisting essentially of siloxane units selected from the group consisting of siloxane units of the average unit formula wherein each R radical is selected from the group consisting of alkyl radicals of from 1 to 6 inclusive carbon atoms, cyclohexyl radicals, phenyl radicals, halogenated alkyl radicals of from 1 to 10 inclusive carbon atoms and alkenyl radicals of from 2 to 6 inclusive carbon atoms, each X being selected from the group consisting of hydroxyl radicals, hydrogen radicals and alkoxy radicals of from 1 to 6 inclusive carbon atoms, at least 50 percent of the total amount of R radicals and radicals present in said polydiorganosiloxane being methyl radicals, a having a value of from 0 to 1 inclusive, b having a value of from 1 to 3 inclusive and c having a value of from 0 to 1 inclusive, the sum of a + b having a value of from 1 to 3 inclusive, the sum of a + c having a value of from 0 to 1 inclusive, the values of a, b and c being such that the ratio of total R radicals and radicals to total silicon atoms present in said polydiorganosiloxane is in the range of from 1.98/1 to 2.02/1 inclusive, said polydiorganosiloxane having a viscosity of at least 0.1 pascal·seconds at 25°C, and (B) a sufficient amount of a wet, fluid filler composition to provide from 15 to 120 parts by weight per 100 parts by weight of (A) of a hydrophobic reinforcing silica filler consisting essentially of surface-treated silica particles wherein said particles consist essentially of Si0 4/2 units containing a sufficient amount of organosiloxy units chemically bonded to the surface of said particle to render the silica filler hydrophobic, said organosiloxy units being selected from the group consisting of R 3 SiO 1/2 units, R 2 SiO units, O 1 / 2 R 2 SiO(R 2 SiO) d SiR 2 O 1/2 units, XR 2 SiO(R 2 SiO) d SiR 2 O 1/2 units and mixtures thereof where each R and each X are as above and d has an average value of from 1 to 12 inclusive, to form a mixture,
Claim 13
Dependent Claim
137 words
(II) removing the volatile portion of said mixture whereby an optically clear composition curable to an elastomer is obtained, and wherein substantially all of said particles of (B) are sufficiently small in their largest 'dimension such that, when the volatile portion has been removed, the mixture of (A) and (B) is an optically clear composition possessing a luminous transmittance value of at least 85% and a haze value of no greater than 4% per 2.54 millimeter thickness of said composition at 23°+2°C according to the procedure set'out in ASTM D1003-61 and wherein the haze value of a composition consisting of a mixture of 100 cubic centimeters of (A) at 23°+2°C and 60 grams of (B) does not increase by more than 1% per 2.54 millimeter thickness of said mixture upon heating the mixture from 23°+2°C to 100°+5°C.
Claim 14
Dependent Claim
137 words
(II) removing the volatile portion of said mixture whereby an optically clear composition curable to an elastomer is obtained, and wherein substantially all of said particles of (B) are sufficiently small in their largest 'dimension such that, when the volatile portion has been removed, the mixture of (A) and (B) is an optically clear composition possessing a luminous transmittance value of at least 85% and a haze value of no greater than 4% per 2.54 millimeter thickness of said composition at 23°+2°C according to the procedure set'out in ASTM D1003-61 and wherein the haze value of a composition consisting of a mixture of 100 cubic centimeters of (A) at 23°+2°C and 60 grams of (B) does not increase by more than 1% per 2.54 millimeter thickness of said mixture upon heating the mixture from 23°+2°C to 100°+5°C.
References Cited (Backward Citations)
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