摘要:
This invention pertains to novel silanes wherein the silicon atom is bonded to at least one ketoximo group and a carbon atom of a primary or secondary amino group. The remaining substituents on the silicon atom are alkoxy groups and/or monovalent hydrocarbon radicals.
摘要:
The reduction in tensile strength exhibited in high humidity environments by "soft" polyurethanes prepared from aliphatic or cycloaliphatic diisocyanates can be substantially reduced if the molar ratio of diisocyanate and chain extender to isocyanate-reactive species other than said chain extender in the reaction mixtures from which said polyurethanes are prepared is at least 4.
摘要:
A method of producing elastomeric silicone foams from a two-part system is disclosed. The method mixes the ingredients then allows a froth to form and cure at ambient temperature to an elastomeric silicone foam. The method mixes a vinyl-containing polydiorganosiloxane (1), a hydroxylated polydiorganosiloxane (2), a platinum catalyst (3), an organohydrogensiloxane (4) and a profoamer (5). The profoamer is a resinous, benzene-soluble organosiloxane copolymer consisting essentially of SiO.sub.4/2 units, silicone bonded hydroxyl groups, (CH.sub.3).sub.3 SiO.sub.1/2 units, and fluorine-containing units. An embodiment of the method includes a liquified blowing agent and stores the mixture under superatmospheric pressure, forming a foam by releasing the mixture to atmospheric pressure. Another embodiment includes an alcohol in the mixture to provide a foam of lower density. when lauryl alcohol is used and the alcohol is mixed with (1), (3), and (5) before (2) is admixed, the foam has a Bashore resiliency of less than 20.
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:
Polyorganosiloxane foams are obtained by blending, dispensing and curing two-part polyorganosiloxane compositions comprising a liquid hydroxyl endblocked polydimethylsiloxane, a liquid alkyl orthosilicate as the curing agent, a catalytically effective amount of a tin compound, a blowing agent and, as a foam stablilizer, a resinous organosiloxane copolymer comprising trimethylsiloxy units, SiO.sub.4/2 units and a specified class of fluorine-containing organosiloxane units.
摘要:
Polyorganosiloxane foams exhibiting a desirable combination of low density, an average cell size between 0.2 and 4 mm and a cell concentration of at least 4 per linear centimeter are obtained by dispensing and curing moisture curable organosiloxane compositions containing a dispersed liquid or gaseous blowing agent and, as a foam stabilizer, a resinous organosiloxane copolymer comprising trimethylsiloxy units, SiO.sub.4/2 units and fluorine-containing organosiloxane units. The polymer portion of the organosiloxane compositions can be a polydimethylsiloxane or a graft copolymer comprising at least 20 mole percent of dimethylsiloxane units in combination with organic units.
摘要:
Compositions, stable in the absence of oxygen, are formed by mixing the following substantially in the absence of oxygen:(A) 100 parts by weight of at least one mercapto-functional organosiloxane containing at least two mercapto-functional substituents per molecule;(B) a catalytic amount of an iron carbonyl compound catalyst selected from the group consisting of Fe(CO).sub.5, Fe.sub.2 (CO).sub.9, Fe.sub.3 (CO).sub.12, dicyclopentadienyldiiron tetracarbonyl, butadieneiron tricarbonyl and cyclohexadieneiron tricarbonyl, preferably from 0.1 to 6 parts by weight of catalyst per 100 parts by weight of part (A);(C) optionally, at least one filler; and(D) 0.1 to 6 parts by weight per 100 parts by weight of a redox compound such as copper (II) sulfate or iron (III) oxide.The compositions polymerize or cure to form higher molecular weight products upon exposure to oxygen. The use of a redox compound appears to increase the cross-link density of the cured composition and results in harder resins and more durable elastomers. An important novel feature of the redox compounds is that their use enables one to formulate compositions which cure to low-modulus elastomers possessing excellent unprimed adhesion to many common substrates such as glass, metal and concrete. Such low-modulus elastomeric compositions are very desirable for use as building sealants.
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:
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:
Mixing mercaptoorganopolysiloxanes, organic peroxide and optionally a filler provides a composition which cures to an elastomer either at room temperature or by heating. The elastomers have tack free surfaces and are useful as sealants and rubber articles.