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 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.
摘要:
This invention relates to a radiation curable silicone compositions. More particularly this invention relates to radiation curable silicone compositions comprising a vinyl ether functional silicon compound, a cationic photoinitiator, a free radical photoinitiator, and dodecylphenol. The compositions of this invention can further comprise a vinyl ether compound which is free of silicon atoms. The radiation curable silicone compositions of this invention are useful as release coating compositions which are especially suitable for release of pressure sensitive adhesives.
摘要:
Azasilacyclopentanes of the general formula ##STR1## are prepared by reacting a dialkoxyalkyl(3-chloro-2-alkylpropyl)silane with a Grignard reagent of the formula R.sup.1 MgBr in the presence of an ether, to make an alkoxyalkylalkenyl(3-chloro-2-alkylpropyl)silane which is reacted with acetyl chloride and a Lewis acid to make chloroalkylalkenyl(3-chloro-2-alkylpropyl)silane which is then reacted with an amine of the formula R.sup.3 NH.sub.2 to make the azasilacyclopentanes.
摘要:
Compositions which cure by UV radiation in less than one second are obtained by mixing an alkenyl containing polydiorganosiloxane, a mercapto functional crosslinker of the mercapto functional polyorganosiloxane or mercapto organic compounds, a photosensitizer, a viscosity stabilizer, and optionally a reinforcing agent. These compositions can be packaged in one container and can be used as the primary coating for optical fibers.
摘要:
Storage stable, one part organosiloxane compositions that cure upon heating by a platinum-catalyzed hydrosilation reaction comprise, in addition to the organosiloxane reactants, a platinum-containing hydrosilation catalyst that is microencapsulated within one or two layers of thermoplastic organic polymers. The microcapsules are formed using known techniques.
摘要:
This present invention provides aqueous emulsions which are capable of depositing coatings and membranes of hydrophilic, water-absorbing silicone-organic polymer elastomers. The elastomers are free radical polymerized copolymers of (A) from 50 to 95 parts by weight of block copolymers containing polydiorganosiloxane segments and polyalkyleneoxy segments which block copolymers contain terminal aliphatically unsaturated groups such as those derived from the reaction of isocyanatoethyl methacrylate with terminal free hydroxyl groups present on the polyalkyleneoxy segments and (B) from 5 to 50 parts by weight of at least one substantially water insoluble aliphatically unsaturated organic monomer which is compatible with (A) such as methyl methacrylate. The aqueous emulsions are useful for forming coatings and membranes of the above elastomers and also provide a vehicle for the deposition of coatings of such elastomers which are capable of controllably releasing bioactive agents such as insecticides or herbicides which are dispersed within the elastomer film deposited from the aqueous emulsion.
摘要:
Cluster azasilacycloalkyl functional polysiloxanes are prepared by combining vinyl-containing polysiloxane, polyfunctional hydrogen polysiloxane, and a platinum catalyst; reacting the combination to produce .tbd.Si--CH.sub.2 CH.sub.2 --Si.tbd. linkages and substantial amounts of unreacted Si--H groups remain in the reaction product. The Si--H groups in the reaction product are reacted with aliphatically unsaturated azasilacycloalkane forming the cluster compound. These cluster azasilacycloalkyl functional polysiloxanes cure when exposed to moisture to elastomers, sealants, encapsulants, and resins products.
摘要:
Compositions which cure by UV radiation in less than one second are obtained by mixing an alkenyl containing polydiorganosiloxane, a mercapto functional crosslinker of the mercapto functional polyorganosiloxane or mercapto organic compounds, a photosensitizer, a viscosity stabilizer, and optionally a reinforcing agent. These compositions can be packaged in one container and can be used as the primary coating for optical fibers.
摘要:
Storage stable and gel-free organosiloxane compositions in the form of flowable powders are prepared by blending a high consistency polydiorganosiloxane into a quantity of fluidized reinforcing filler that is heated to a temperature of from 100.degree. to 200.degree. C. prior to or immediately following introduction of the polydiorganosiloxane. When silica is the reinforcing filler, the filler is typically treated with an anti-creping agent either prior to or during this blending process. The resultant mixture is heated while being subjected to shearing forces that reduce its average particle size to achieve a flowable powder.