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US 6,660,787 B2Granted
Transparent, fire-resistant polycarbonate compositions
AssigneeGeneral Electric Company
InventorsJames Alan Mahood, Niles Richard Roscnquist, Rajendra Kashinath Singh
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Abstract
A transparent, fire resistant branched polycarbonate-polysiloxane composition comprises polycarbonate, a short-chained polydiorganosiloxane, a branching agent, and flame retardants essentially free of bromine or chlorine, wherein the amount of short-chained polydiorganosiloxane is about 1 wt. % or less.
Claims19
A transparent, fire resistant, branched polycarbonate-polysiloxane block copolymer composition comprising:
- a) polycarbonate blocks having recurring units of the formula:
- wherein Ra and Rb each represent a monovalent hydrocarbon group and may be the same or different;
- p and q are each independently integers from 0 to 4;
- and Xa represents one of the groups of formula:
- wherein Rc and Rd each independently represent a hydrogen atom or a monovalent linear or cyclic hydrocarbon group and Rc is a divalent hydrocarbon group;
- b) a repeating or recurring polysiloxane unit derived from the reaction product of an allyl phenol and a polydiorganosiloxane of the formula:
- wherein R1 and R2 are each independently hydrocarbyl and where D is an integer of from about 5 to about 20;
- c) a polyfunctional organic branching agent containing at least three functional groups selected from the group consisting of hydroxyl, carboxyl, carboxylic anhydride, carboxylic acid chloride, and mixtures thereof;
- and
- d) flame retardant additives;
- wherein said polysiloxane unit is present in an amount of about 1 wt. % or less, based on the total weight of said branched polycarbonate-polysiloxane block copolymer.
8 more elements
A process for preparing a thermoplastic randomly branched polycarbonate-polysiloxane block copolymer composition, the process comprising:
- a) charging to a reactor:
- i. a dihydric phenol;
- ii. a polysiloxane unit diol derived from the reaction product of an allyl phenol and a diorganopolysiloxane of the formula:
- wherein R1 and R2 are each independently hydrogen, or hydrocarbyl and where D is an integer of from about 5 to about 20 and wherein said polysiloxane unit is present in an amount of about 1 wt. % or less based on the total weight of said branched polycarbonate-polysiloxane block copolymer
- iii. water,
- iv. a polyfunctional organic compound as a branching agent containing at least three functional groups selected from the group consisting of hydroxyl, carboxyl, carboxylic anhydride, carboxylic acid chloride, and mixtures thereof;
- v. a catalytic proportion of a catalyst;
- to form a heterogeneous reaction mixture having an organic phase and an aqueous phase;
- b) agitating the reaction mixture to enhance the contact between the phases;
- c) adding to the reaction mixture a carbonate precursor, and
- d) copolymerizing the dihydric phenol, the branching agent, and the polysiloxane diol.
8 more elements
Dependencies are inferred from the claim text.