摘要:
A method of producing hydrophobic colloidal silica is disclosed. The method comprises combining an aqueous colloidal silica dispersion, polyorganosiloxane, and anionic surfactant to yield a stable aqueous emulsion of hydrophobic colloidal silica. The emulsion may be further processed by evaporating the water to yield a white material which may be easily ground to a fine powder of hydrophobic colloidal silica. This powder is useful as a reinforcement for silicone rubber.
摘要:
A method of producing hydrophobic colloidal silica is disclosed. The method comprises combining an aqueous colloidal silica dispersion, polyorganosiloxane, and anionic surfactant to yield a stable aqueous emulsion of hydrophobic colloidal silica. The emulsion may be further processed by evaporating the water to yield a white material which may be easily ground to a fine powder of hydrophobic colloidal silica. This powder is useful as a reinforcement for silicone rubber.
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:
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:
The impact strength of certain thermoplastic vinylic polymers is improved by polymerizing the corresponding monomers in an emulsion of a diorganosiloxane containing units of the formula HSR'SiR.sub.n O.sub.3--n/2. For example a styrene acrylonitrile copolymer containing 20 percent by weight of a dimethylsiloxane-3-mercaptopropylsiloxane copolymer having 1 mol percent mercaptosiloxane has an Izod notched impact strength of 10.8 foot pounds per inch.
摘要:
An aqueous dispersion comprising a copolymer which is the polymerization product of a mixture of vinylic monomers wherein from about 5% to about 90% by weight of the vinylic monomers are selected from co-esters of a drying oil acid and an unsaturated &agr;, &bgr;-polymerizable unsaturated carboxylic acid, contains from about 0.5% to about 50% by weight based on the weight of the copolymer of a hydrophobic ester or partial ester of a drying oil acid and a polyol. The copolymer polymerized in the presence of the hydrophobic ester or partial ester is characterized by a relatively low gel content, and by a relatively broad, multi-nodal, molecular weight distribution, including a low molecular weight component which acts as a transient plasticizer and coalescing agent. The aqueous dispersions can be formulated into quick drying coating compositions which form smooth protective films on various substrates, without requiring volatile coalescing agents.
摘要:
The present invention is stereoregular poly{methyl(3,3,3-trifluoropropyl)siloxane} polymers and copolymers and methods for their making. The process involves reacting isomers of 1,3,5-trimethyl-1,3,5-tris(3',3',3'-trifluoropropyl)cyclotrisiloxane in the presence of an aprotic polar promoter and a lithium compound. The lithium compound initiates ring opening and polymerization of the isomers without effecting the steric arrangement of the isomers. Elastomers prepared by cross-linking polymers of the present invention can have sufficient cis 3,3,3-trifluoropropyl substitution to allow the elastomers to strain crystallize and provide reinforcement to the elastomers at typical use temperatures.
摘要:
Polyesters are prepared by reacting aqueous compositions containing an emulsified hydroxyacid or an emulsified mixture comprising a polyfunctional carboxylic acid or anhydride and a polyfunctional alcohol. The emulsion also contains a suitable polycondensation catalyst. The resultant polyesters are useful as plasticizers and as precursors for alkyd resins and other polymers.
摘要:
An aqueous silicone emulsion is described which provides an elastomeric product upon removal of the water under ambient conditions. The emulsion comprises a continuous water phase and a dispersed phase of crosslinked silicone. The silicone phase is the product of radical produced crosslinking of hydroxyl endblocked polydiorganosiloxane. The polydiorganosiloxane is crosslinked after it has been dispersed in water. Preferred polydiorganosiloxanes contain vinyl-substituted siloxane units and can be crosslinked by high energy radiation or the combined action of heat and an organic peroxide.
摘要:
A silicone emulsion having a dispersed phase of an anionically stabilized hydroxylated polydiorganosiloxane and a colloidal silica and a continuous phase of water in which the pH is 9 to 11.5 provides an elastomeric product, such as a film or coating, upon removal of the water at ambient conditions. The silicone emulsion can be prepared by adding the colloidal silica to the hydroxylated polydiorganosiloxane in an emulsified state and thereafter adjusting the pH within the range of 9 to 11.5 inclusive with such materials as an organic amine or sodium hydroxide. These emulsions are stable during storage over extended periods of time and will provide elastomeric products. A silicone emulsion can also be prepared as described except the pH is adjusted above 11.5.