Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Reexamination Certificate
1999-12-08
2001-07-24
Moore, Margaret G. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
C528S032000, C528S035000, C556S434000, C556S451000
Reexamination Certificate
active
06265518
ABSTRACT:
FIELD OF THE INVENTION
An organosilicon compound comprising one silicon-bonded hydrogen atom described by formula
or by formula
where each R
1
and R
1′
is an independently selected hydrocarbon radical free from aliphatic unsaturation comprising 1 to about 18 carbon atoms; each R
2
is an independently selected hydrocarbon radical free from aliphatic unsaturation comprising 1 to about 18 carbon atoms; each X and X′ is independently selected from the group consisting of halogen, alkoxy, acyloxy, and ketoximo; t is 2 or 3; n is 0, 1, or 2; and each Z is independently selected from the group consisting of divalent hydrocarbon radicals free of aliphatic unsaturation comprising about 2 to 18 carbon atoms and a combination of divalent hydrocarbon radicals and siloxane segments.
BACKGROUND OF THE INVENTION
Polyorganosiloxane compositions which cure to elastomeric materials at room temperature are well known. Such compositions can be obtained by mixing polydiorganosiloxanes having reactive or hydrolyzable groups, such as silanol or alkoxy groups, with silane crosslinking agents, for example, alkoxysilanes, acetoxysilanes, oximosilanes, or aminosilanes, and catalysts as needed. Generally, the polydiorganosiloxanes may have 1 to 3 reactive groups per chain end. Compositions comprising these ingredients can then be cured by exposure to atmospheric moisture at room temperature.
The cure rate of a particular composition is dependent on a number of factors including the type of reactive or hydrolyzable group utilized. It is known that different hydrolyzable groups have different reactivities and even the same type of hydrolyzable group can have different reactivities. For example, in the presence of moisture, a silicon-bonded acetoxy group will hydrolyze more rapidly than a silicon-bonded alkoxy group. In addition if, for example, a silicon-bonded trialkoxy group is present on a polymer, it is believed that each silicon-bonded alkoxy group has a different reactivity, with the alkoxy group first reacted being “most reactive.” Generally, once the first alkoxy group on a silicon atom reacts it takes a longer time for the second alkoxy group on the same silicon atom to react, and even longer for the third. Therefore, it would be desirable to prepare an organosilicon compound which can endcap a polymer and be capable of providing more than one “most” reactive hydrolyzable group per polymer chain end.
The objective of the present invention is to prepare an organosilicon compound comprising one silicon-bonded hydrogen atom which is capable of endcapping a polymer and providing more than one “most” reactive hydrolyzable group per polymer chain end.
SUMMARY OF THE INVENTION
The present invention is an organosilicon compound comprising one silicon-bonded hydrogen atom described by formula
or by formula
where each R
1
and R
1′
is an independently selected hydrocarbon radical free from aliphatic unsaturation comprising 1 to about 18 carbon atoms; each R
2
is an independently selected hydrocarbon radical free from aliphatic unsaturation comprising 1 to about 18 carbon atoms; each X and X′ is independently selected from the group consisting of halogen, alkoxy, acyloxy, and ketoximo; t is 2 or 3; n is 0, 1, or 2; and each Z is independently selected from the group consisting of divalent hydrocarbon radicals free of aliphatic unsaturation comprising about 2 to 18 carbon atoms and a combination of divalent hydrocarbon radicals and siloxane segments.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is an organosilicon compound comprising one silicon-bonded hydrogen atom described by formula
or by formula
where each R
1
and R
1′
is an independently selected hydrocarbon radical free from aliphatic unsaturation comprising 1 to about 18 carbon atoms; each R
2
is an independently selected hydrocarbon radical free from aliphatic unsaturation comprising 1 to about 18 carbon atoms; each X and X′ is independently selected from the group consisting of halogen, alkoxy, acyloxy, and ketoximo; t is 2 or 3; n is 0, 1, or 2; and each Z is independently selected from the group consisting of divalent hydrocarbon radicals free of aliphatic unsaturation comprising about 2 to 18 carbon atoms and a combination of divalent hydrocarbon radicals and siloxane segments described by formula
where R
2
is as defined above; each G is an independently selected divalent hydrocarbon radical free of aliphatic unsaturation comprising about 2 to 18 carbon atoms; and c is a whole number from 1 to about 6.
In formula (1), each R
1
is an independently selected hydrocarbon radical free from aliphatic unsaturation comprising 1 to about 18 carbon atoms. The hydrocarbon radicals free from aliphatic unsaturation represented by R
1
may be substituted or unsubstituted. Examples of hydrocarbon radicals free from aliphatic unsaturation include alkyl radicals, aryl radicals, and aralkyl radicals. Examples of alkyl radicals include methyl, ethyl, hexyl, octadecyl, cyclobutyl, cyclopentyl, cyclohexyl, 3,3,3-trifluoropropyl, chloromethyl, and chlorocyclopentyl. Examples of aryl radicals include phenyl, tolyl, xylyl, 2,4-dichlorophenyl, and tetrachlorophenyl. Examples of aralkyl radicals include benzyl, beta-phenylethyl, gamma-tolylpropyl, para-chlorobenzyl, and 2-(bromophenyl)propyl. Preferably, each R
1
is selected from the group consisting of alkyl radicals comprising 1 to about 8 carbon atoms and aryl radicals comprising about 6 to 8 carbon atoms. More preferably, R
1
is an alkyl radical comprising 1 to about 8 carbon atoms. Most preferably, R
1
is n-propyl.
In formula (IA), each R
1′
is an independently selected hydrocarbon radical free from aliphatic unsaturation comprising 1 to about 18 carbon atoms. The hydrocarbon radicals free from aliphatic unsaturation represented by R
1′
may be substituted or unsubstituted. Examples of hydrocarbon radicals free from aliphatic unsaturation include alkyl radicals, aryl radicals, and aralkyl radicals. Examples of R
1′
are as described above for R
1
. Preferably, each R
1′
is selected from the group consisting of alkyl radicals comprising 1 to about 8 carbon atoms and aryl radicals comprising about 6 to 8 carbon atoms. More preferably, R
1′
is an alkyl radical comprising 1 to about 8 carbon atoms. Most preferably, R
1′
is methyl.
In formulas (1) and (IA), each R
2
is an independently selected hydrocarbon radical free from aliphatic unsaturation comprising 1 to about 18 carbon atoms. The hydrocarbon radicals free from aliphatic unsaturation represented by R
2
may be substituted or unsubstituted. Examples of hydrocarbon radicals free from aliphatic unsaturation include alkyl radicals, aryl radicals, and aralkyl radicals. Examples of R
2
are as described above for R
1
. Preferably each R
2
is an independently selected alkyl radical. More preferably each R
2
is an independently selected alkyl radical comprising 1 to about 8 carbon atoms. Most preferably each R
2
is methyl.
In formula (1), each X is independently selected from the group consisting of halogen, alkoxy, acyloxy, and ketoximo. The halogen atoms can be chlorine, bromine, fluorine, and iodine. Examples of alkoxy groups include methoxy, ethoxy, iso-propoxy, butoxy, cyclohexoxy, phenoxy, 2-chloroethoxy, 3,3,3-trifluoropropoxy, 2-methoxyethoxy, and p-methoxyphenoxy. Examples of acyloxy groups include acetoxy, propionoxy, benzoyloxy, and cyclohexoyloxy. Examples of ketoximo groups include dimethylketoximo, methylethylketoximo, methylpropylketoximo, methylbutylketoximo, and diethylketoximo. Preferably each X is independently selected from the group consisting of alkoxy, acyloxy, and ketoximo. More preferably each X is independently selected from the group consisting of alkoxy and acyloxy, with each X being an independently selected alkoxy group being most preferred.
In formula (1), each X′ is independently selected from the group consisting of halogen, alkoxy, acyloxy, and ketoximo. Examples of X′ are as described above for X. Preferably eac
Krahnke Robert Harold
Lueder Timothy B.
Palmer Richard Alan
Shephard Nick Evan
Dow Corning Corporation
Moore Margaret G.
Scaduto Pamela M.
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