摘要:
A composition curable to a silicone elastomer is prepared by mixing a triorganosiloxy endblocked polydimethylsiloxane fluid where the triorganosiloxy is dimethylvinylsiloxy or methylphenylvinylsiloxy, a reinforcing silica having a surface treated organosiloxane groups which contain 0.05 to 0.32 percent by weight vinyl, a fluid organohydrogensiloxane, a platinum catalyst and optionally a platinum catalyst inhibitor. The polydimethylsiloxane fluid has a major peak molecular weight of 68,000 to 135,000, a dispersity index greater than 3.8, the lowest molecular weight species between 854 and 3146 and the highest molecular weight species between 174,000 and 370,000. These compositions are readily extrudable under low pressure and cure to high strength elastomers with a high durometer.
摘要:
Polymethylsiloxanes containing silicon-bonded hydrogen exhibit low temperature properties and can be made into gels with which also exhibit low temperature properties or into elastomeric materials. The polymethylsiloxanes have 84 to 96 mole percent dimethylsiloxane units, 0.5 to 6 mole percent trimethylsiloxy units, 2 to 10 mole percent methylsilsesquioxane units, and 0.25 to 3 mole percent monohydrogendimethylsiloxy units and the total mole percent of the trimethylsiloxy units and the monohydrogendimethylsiloxy units is at least 1.5.
摘要:
A fluorosilicone rubber with low compression set and other physical properties which are either are not significantly effected or are improved are made by curing a composition of a polydiorganosiloxane having 3,3,3-trifluoropropylsiloxane units and endblocked with vinyl or silacyclopentenyl groups, a reinforcing silica having dimethyl(3,3,3-trifluoropropyl)siloxy units as the surface treatment, and a vinyl specific organic peroxide. The polydiorganosiloxane endblocking is done by reacting a silanol endblocked polymer with a silazane.
摘要:
Vinyl and allyl containing bis(polydimethylsiloxanyl)amine compounds are useful as a treating agent for pinely divided silica when used in conjunction with conventional silazanes. The in situ filler treatment using the amine compounds and silazanes allows the production of easily extrudable compositions which cure to silicone elastomers with unique property profiles.
摘要:
Polyorganosiloxane foams are prepared by the volatilization of a blowing agent within a polyorganosiloxane composition that is curable by a hydrosilation reaction and includes as a foam stabilizer a resinous polyorganosiloxane comprising trimethylsiloxy units, SiO.sub.4/2 units and a specified class of fluorine-containing siloxane units.
摘要:
An improved treatment for reinforcing silica uses both a silazane represented by the formula (RR'R"Si).sub.2 NH and bis-Si-(1-methyl-1-silacyclopentenyl) amine as filler treatment. The filler treatment may be done either in situ during the manufacture of curable silicone elastomer compositions or as a separate operation. The treatment allows production of an easily extrudable composition with improved durometer and tear strength.
摘要:
Polyorganosiloxane foams are prepared by the volatilization of a blowing agent within a polyorganosiloxane composition that is curable by a hydrosilation reaction and includes as a foam stabilizer a resinous polyorganosiloxane comprising trimethylsiloxy units, SiO.sub.4/2 units and a specified class of fluorine-containing siloxane units.
摘要:
Organosilicon compositions comprising at least one silicon-bonded alkenyloxy radical, such as vinyldimethylcarbonoxy, are disclosed. These unsaturated organosilicon compositions are useful as partial or complete replacements for the analogous organosilicon compositions bearing the well-known silicon-bonded vinyl radical. In particular, vinyldimethylcarbinoxy-endblocked polydimethylsiloxane is useful as a component in an elastomeric composition which is cured with an organosilicon hydride.
摘要:
Continuously passing a mixture of an acetylenic alcohol and a siloxane compound having at least three silicon-bonded hydrogen atoms bonded to at least three different silicon atoms in the presence of a platinum catalyst through a heating means wherein the mixture is heated above 100.degree.C. and above the temperature at which the olefinic siloxane compound product is no longer an inhibitor for the reaction and wherein the reactants and products are maintained under sufficient pressure to keep the mixture in a liquid state at least until the mixture has passed through the heating means provides an olefinic siloxane compound which, below 100.degree.C, is an inhibitor for the reaction between the acetylenic alcohol, the siloxane compound having at least three silicon-bonded hydrogen atoms in the presence of platinum.
摘要:
A method of producing a one-part silicone elastomeric sealant which has improved shelf life and an economical process of manufacture is disclosed. The method mixes a diorganovinylsiloxy endblocked polydiorganosiloxane, reinforcing filler, and a silazane. This reinforced base is then converted by reacting with a silane of the formulaH[SiR.sub.2 OSiR.sub.2 CH.sub.2 CH.sub.2 ].sub.b SiR.sub.a (OR").sub.3-awhere R is methyl, ethyl, propyl, phenyl or trifluoropropyl, R" is methyl or ethyl, a is 0 or 1, and b is 0 or 1 using a platinum catalyst. The result is a base containing an alkoxy functional polymer. This base is then mixed with alkoxy functional silane crosslinker and titanium catalyst to yield a composition which is stable in the absence of moisture for long periods of time in storage, but cures to an elastomer upon exposure to moisture. The improved shelf life is due to the presence of alkylene radicals between the penultimate silicon atom and the last silicon atom of the polymer.