摘要:
A UV curable composition of a specific organopolysiloxane having mercaptoalkyl and phenylene groups and a vinyl-containing organopolysiloxane cures into a film which emits little stimulative sulfur odor and has enough resistance to light or UV radiation to retain its as-cured properties even after long-term exposure to sunlight or UV radiation.
摘要:
The coated optical fiber of the invention is prepared by providing a coating layer of an ultraviolet-curable organopolysiloxane or a composition comprising the same and irradiating the coating layer with ultraviolet. Specifically, each of the terminal silicon atoms of the organopolysiloxane, which preferably has a linear molecular structure, has two or more ethylenically unsaturated polymerizable groups bonded thereto through an oxygen atom, such as CH.sub.2 .dbd.CHCOOCH.sub.2 CH.sub.2 --, [CH.sub.2 .dbd.C(CH.sub.3)COOCH.sub.2 ].sub.3 C--CH.sub.2 -- and (CH.sub.2 .dbd.CHCOOCH.sub.2).sub.2 C(C.sub.2 H.sub.5)CH.sub.2 --. By virtue of this unique molecular structure of the organopolysiloxane, the coating layer is rapidly cured by ultraviolet irradiation to give a cured coating layer exhibiting very low water absorption and small temperature dependency of the Young's modulus at low temperatures.
摘要:
A composition comprising (a) an organopolysiloxane having a unit of the formula: RSiO.sub.3/2 wherein R is a substituted or unsubstituted monovalent C.sub.1-10 hydrocarbon group in its molecule and having at least 0.05 alkenyl groups each directly attached to a silicon atom per silicon atom, (b) an organohydrogenpolysiloxane having at least 2 hydrogen atoms each directly attached to a silicon atom per molecule, and (c) a platinum catalyst, maintains good light transmission in cured form when exposed to humidity or stresses and is thus suitable for forming cores of optical fibers.
摘要:
The coated optical fiber of the invention is prepared by providing a coating layer of an ultraviolet-curable organopolysiloxane or a composition comprising the same and irradiating the coating layer with ultraviolet. Specifically, each of the terminal silicon atoms of the organopolysiloxane, which preferably has a linear molecular structure, has two or more ethylenically unsaturated polymerizable groups bonded thereto through an oxygen atom, such as CH.sub.2 .dbd.CHCOOCH.sub.2 CH.sub.2 --, [CH.sub.2 .dbd.C(CH.sub.3)COOCH.sub.2 ].sub.3 C--CH.sub.2 --and (CH.sub.2 .dbd.CHCOOCH.sub.2).sub.2 C(C.sub.2 H.sub.5)CH.sub.2 --. By virtue of this unique molecular structure of the organopolysiloxane, the coating layer is rapidly cured by ultraviolet irradiation to give a cured coating layer exhibiting very low water absorption and small temperature dependency of the Young's modulus at low temperatures.
摘要:
In the alkenyl-containing diorganopolysiloxane of the invention, the distribution of the alkenyl groups in the molecule is not random as in conventional alkenyl-containing diorganopolysiloxanes but each of at least three siloxane units linked to each of the terminal silicon atoms has an alkenyl, e.g. vinyl, group while at least six of the uninterruptedly linked siloxane units excepting the above mentioned alkenyl-containing units adjacent to the molecular chain ends are free from aliphatic unsaturation. A method for the preparation of the diorganopolysiloxane having the alkenyl groups in such a localized distribution is disclosed. When the diorganopolysiloxane is used as the principal ingredient of a curable organopolysiloxane composition as combined with a crosslinking agent, the composition, despite its relatively low viscosity, can give a cured rubber having markedly improved mechanical strengths.
摘要:
The inventive method for forming a cured film on a substrate surface comprises coating the surface with a room temperature curable organosiloxazane polymer comprising, in a molecule, (a) at least one organosiloxane unit represented by the unit formula (a) at least one organosiloxane unit represented by the unit formulaR.sup.1.sub.a SiO.sub.(4-a)/2,and (b) at least one organosilazane unit represented by the unit formulaR.sup.2.sub.b Si(NR.sup.3).sub.(4-b)/2,in which R.sup.1, R.sup.2 and R.sup.3 are each a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group, not all of them being simultaneously hydrogen atoms, and the subscripts a and b are each a positive integer of 1, 2 or 3 with the proviso that a and b cannot be simultaneously equal to 3, in a molecule and subjecting the coating film to exposure to a moisture-containing atmosphere. The method is useful for forming a surface-protecting film or for imparting surface releasability.
摘要:
Whereas the mechanism for the crosslink formation in the curable organopolysiloxane composition of the invention is the ultraviolet-induced addition reaction between alkenyl, e.g., vinyl, groups in a diorganopolysiloxane and mercaptoalkyl groups in another organopolysiloxane as in conventional compositions, the mercaptoalkyl-containing organopolysiloxane used in the invention is, differently from those in conventional compositions, an organopolysiloxane of a three-dimensionally branched molecular structure as composed of the siloxane units of the formulas R.sup.1.sub.3 SiO.sub.0.5, R.sup.1.sub.a (HSR.sup.2)SiO.sub.(3-a)/2 and SiO.sub.2, in which R.sup.1 is, for example, a methyl or phenyl group, R.sup.2 is, for example, --CH.sub.2 CH.sub.2 CH.sub.2 -- and a is zero, 1 or 2, in a specified proportion. In addition, the vinyl group-containing siloxane units in the vinyl-containing diorganopolysiloxane are localized in the molecular structure forming two blocks each bonded to one of the terminal silicon atoms. The inventive composition is advantageous in respect of the greatly improved mechanical strengths of the cured silicone rubber obtained by irradiating the composition with ultraviolet light.
摘要:
Provided herein is an ultraviolet-curable gel composition which comprises an organopolysiloxane as a principal component which is represented by the general structural formula below. ##STR1## where R.sup.1 is a C.sub.4-25 monovalent organic group containing therein 1 to 2 vinyl functional groups; R.sup.2 is a C.sub.1-18 monovalent organic group having no vinyl group capable of addition polymerization; R.sup.3 is a C.sub.2-4 divalent hydrocarbon group; R.sup.4 is a C.sub.1-9 substituted or unsubstituted hydrocarbon group of the same or different kind; a is an integer of 1 to 3; and n is an integer of 5 to 500.
摘要:
Polyorganosilanes are prepared by contact reaction of organodihalosilanes with alkali metal fine particles in an organic solvent. Prior to the contact reaction, a triorganohalosilane is contacted with the dispersion of alkali metal fine particles in organic solvent for removing reactive oxygen and moisture from the dispersion. Formation of a siloxane bond in the polysilane backbone is minimized, and polyorganosilanes having a minimal oxygen content are obtained.
摘要:
Polyorganosilanes are prepared through contact reaction of an organodihalosilane with alkali metal fine particles dispersed in an organic solvent. the reaction solution is adjusted to an acidity of pH 3 to 7 before or after the step of deactivating the excess alkali metal in the reaction solution. The alkali metal halide is removed from the reaction solution by dissolving it in water. Formation of insoluble components is minimized.