Method of producing treated silica filler for silicone rubber
First Claim
1. A method of rapidly treating the surface of reinforcing silica filler consisting essentially of mixing, at a temperature of from about -10°
- to 130°
C.,(A) 100 parts by weight of reinforcing silica filler, having a surface area of greater than 50 m2 /g, and having from 0.5 to 6 parts by weight of absorbed moisture,(B) from 3 to 30 parts by weight of volatile treating agent of the formula Rx Si(OR'"'"')4-x, wherein R is a alkyl, alkenyl, or aryl radical having from 1 to 6 carbon atoms which may be substituted with halogen atoms, R'"'"' is an alkyl radical having from 1 to 3 carbon atoms, x is 1 or 2, and R and R'"'"' are chosen so that the vapor pressure of the alkoxysilane exceeds 10 Pa at treatment temperature,(C) from 0.001 to 5.0 parts by weight of volatile catalyst selected from the group consisting of base B, and mixtures of acid A and base B, wherein acid A is a volatile acid or acid progenitor, and base B is a silylamine or silazane, acid A and base B being chosen so that the vapor pressure of either acid A or base B exceeds 500 Pa at treatment temperature, for a period of time sufficient to allow the desired amount of treating agent to be adsorbed onto the surface of the particulate filler,to yield a filler which requires a minimum of energy to disperse rapidly into polydiorganosiloxane and which gives improved properties to cured silicone elastomers.
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Accused Products
Abstract
An improved method of producing treated silica filler for use with silicone rubber operates at ambient temperature in a short period of time. The method consists essentially of mixing reinforcing silica with a volatile treating agent of the formula Rx Si(OR'"'"')4 -x, wherein R is a substituted or unsubstituted, saturated or unsaturated, alkyl or aryl radical having from 1 to 6 carbon atoms, R'"'"' is an alkyl radical having from 1 to 3 carbon atoms, x is 1 or 2, and R and R'"'"' are chosed so that the vapor pressure of the alkoxysilane exceeds 10 Pa (0.0001) atmosphere) at treatment temperature, in combination with a volatile catalyst selected from the group consisting of acid A, base B, and mixtures thereof; wherein acid A is a volatile acid or acid progenitor, and base B is a silylamine or silazane, acid A and base B being chosen so that the vapor pressure of either acid A or base B exceeds 500 Pa (0.005 atmosphere) at treatment temperature, for a period of time sufficient to allow the desired amount of treating agent to be absorbed onto the surface of the particulate filler.
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Citations
31 Claims
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1. A method of rapidly treating the surface of reinforcing silica filler consisting essentially of mixing, at a temperature of from about -10°
- to 130°
C.,(A) 100 parts by weight of reinforcing silica filler, having a surface area of greater than 50 m2 /g, and having from 0.5 to 6 parts by weight of absorbed moisture, (B) from 3 to 30 parts by weight of volatile treating agent of the formula Rx Si(OR'"'"')4-x, wherein R is a alkyl, alkenyl, or aryl radical having from 1 to 6 carbon atoms which may be substituted with halogen atoms, R'"'"' is an alkyl radical having from 1 to 3 carbon atoms, x is 1 or 2, and R and R'"'"' are chosen so that the vapor pressure of the alkoxysilane exceeds 10 Pa at treatment temperature, (C) from 0.001 to 5.0 parts by weight of volatile catalyst selected from the group consisting of base B, and mixtures of acid A and base B, wherein acid A is a volatile acid or acid progenitor, and base B is a silylamine or silazane, acid A and base B being chosen so that the vapor pressure of either acid A or base B exceeds 500 Pa at treatment temperature, for a period of time sufficient to allow the desired amount of treating agent to be adsorbed onto the surface of the particulate filler, to yield a filler which requires a minimum of energy to disperse rapidly into polydiorganosiloxane and which gives improved properties to cured silicone elastomers. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
- to 130°
Specification