Albemarle Corporation

Albelmarle Corporation

Homer C Lin

Charles H Kolich

Meng-Sheng Ao

Donald E Balhoff

Billie B Dadgar

David R Brackenridge

Thorsten W Brockmann

Jon S Reed

Susan D Landry

Daniel A De Schryver

Thorsten W Brockman

Novel brominated styrenic polymers having superior properties rendering them ideally suited for current commercial requirements for use as flame retardants in thermoplastic polymers are described. These properties include such high thermal stabilities in a standard Thermal Stability Test as to dramatically reduce if not eliminate the possibility of corrosion problems due to release of hydrogen halide at elevated polymer processing temperatures. Other special properties of the novel brominated styrenic polymers include, for example, low color or staining properties, and excellent melt flow characteristics.

Brominated polystyrenic resins

This invention relates to a thermally stable brominated polystyrene having less than 100 ppm total Cl,, above about 68 wt % bromine and less than about 6,000 ppm hydrolyzable halide. The brominated polystyrene exhibits little or no polymer cross-linking or chain cleavage relative to the starting polystyrene.

Process for brominating polystyrenic resins

These novel brominated styrenic polymers have a bromine content in the range of about 60 to about 66 wt % bromine; a total chlorine content, if any, of less than 700 ppm; a GPC weight average molecular weight in the range of about 500,000 to about 800,000; a DSC glass transition temperature of less than 175&deg; C.; and a thermal stability in the Thermal Stability Test of 250 ppm HBr or less. Such flame retardant polymers exhibit superior performance qualities during use, especially in thermoplastics, including improved melt flow characteristics and improved thermal stability.

A polyalkylene terephthalate polymer, such as polyethylene terephthalate, polybutylene terephthalate, blends or copolymers thereof, and analogous polyester-type engineering thermoplastics, with which has been blended a flame retardant amount of brominated styrenic polymer, such as brominated polystyrene, that, prior to blending, is characterized by (a) containing less than 700 ppm Cl and having a TGA temperature for 1% weight loss of 340&deg; C. or higher; and/or (b) having an actual M,which is within about 20%, and preferably within about 10%, of its calculated theoretical M,, the theoretical M,being based upon the actual bromine content of the brominated styrenic polymer and the M,of the styrenic polymer reactant used to produce the brominated styrenic polymer; and/or (c) being essentially free of each of the following impurities: (1) ethylene dichloride, (2) bromodichloroethane, (3) dibromochloroethane, (4) dibromodichloroethane, and (5) tribrormochloroethane. These compositions most preferably also further comprise a reinforcing amount of glass fiber and/or a flame retardant synergist dispersed therein. It is now possible to provide polyalkylene terephthalate compositions that have a UL-94 rating of V-O using both {fraction (1/16)}-inch test specimens and {fraction (1/32)}-inch test specimens, and that have superior electrical resistance characteristics as reflected by a higher comparative tracking index and greater melt stability as determined by capillary rheometry.

Polymer compositions containing brominated polystyrenic resins

Novel brominated styrenic polymers have an ionic bromine content of 2000 ppm or less, and one or more of the following additional characteristics: (a) a TGA temperature for 1% weight loss which is 340&deg; C. or higher, and a chlorine content, if any, of less than about 700 ppm Cl (b) an actual M,which is within about 20% of the calculated theoretical M,, the theoretical M,being based upon the actual bromine content of the brominated styrenic polymer and the M,of the styrenic polymer reactant used to produce the brominated styrenic polymer; and (c) essentially no content of impurities selected from the group consisting of ethylene dichloride, bromodichloroethane, dibromochloroethane, dibromodichloroethane, and tribromochloroethane. Such flame retardant polymers exhibit superior performance qualities during use, especially in thermoplastics such as glass-filled polyesters and glass-filled nylons.

Brominated polstyrenic resins

Flame retarded thermoplastic polymer compositions are formed by blending together a thermoplastic polymer and at least a flame retardant amount of a brominated styrenic polymer having, prior to blending, a total bromine content of at least about 50 wt % and in addition specified characteristics pertaining to such properties as (i) TGA temperature for 1% weight loss, (ii) hydrolyzable bromine content, (iii) chlorine content (if any), and/or (iv) thermal stability using a described Thermal Stability Test. Blends made with prior art brominated polystyrenes do not possess the enhanced thermal stability and reduced metal corrosiveness provided by these brominated styrenic polymers.

Polymers flame retarded with brominated polystyrenic resins

This invention relates to the bromination of styrenic polymers by contacting same with a brominating agent in the presence of a bromination catalyst and, as a reaction solvent, bromochloro-methane.

Process for brominated styrenic polymers

This invention relates to a thermally stable brominated polystyrene composition which contains alkali metal base (e.g., NaOH) in an amount less than about 1 wt % such that if the flame retardant is dissolved in bromochloromethane and the resultant solution is extracted with water, the resultant water extract exhibits a pH of at least about 9.0. A preferred composition of this type even when heated to 315.degree. C. for one hour did not undergo darkening--the color remained tan. Comparative samples not containing the base turned black under these same conditions. Especially useful compositions additionally have less than 500 ppm, and better still, less than 100 ppm total Cl, and at least about 67 wt % bromine. Processes for producing the compositions are also described.

Brominated polystyrenic flame retardants

This invention relates to the bromination of styrenic polymers by contacting same with a brominating agent in the presence of a bromination catalyst and, as a reaction solvent, bromochloromethane.

This invention features a process for brominating styrenic polymers which process comprises feeding a first stream comprising a brominating agent, a second stream comprising styrenic polymer and a third stream comprising bromination catalyst to a mixer to intimately mix such streams.

This invention features a process for brominating styrenic polymers, which process comprises forming a reaction mass by feeding a mixture, (i) which is substantially free of a bromination catalyst and (ii) which is formed from at least brominating agent and a styrenic polymer, to a catalytic quantity of a bromination catalyst.

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Baton Rouge, LA, United States of America

Homer C Lin