New halogenated FRs.

A brominated flame retardant has been recently added to the Pyronil line of brominated phthalate esters from Elf Atochem North America, Philadelphia. Pyronil 63, (63% bromine) has a melting point of about 230 F that allows it to form a more homogeneous blend than most other filler-type brominated flame retardants--a characteristic Atochem says helps to retain the physical properties, such as impact strength and elongation, of the host resin. This white free-flowing solid is aimed at use in styrenics and engineering resins.

A new product aimed at nylons is Fyrol MC, a new melamine cyanurate flame retardant from Akzo Chemicals Inc., Dobbs Ferry, N.Y. A one-component system, Fyrol MC is said to be active in the vapor phase, causing a dilution of combustible gases near the surface. Flame retardancy is also aided by the endothermic reaction of nitrogenous gas sublimation, resulting in lower combustion temperatures, Akzo says. The additive is thermally stable and reportedly can tolerate processing temperatures above 570 F. In nylon 66, use levels as low as 6.5% can deliver a UL 94V-0; levels of 12-15% will provide the same protection in nylon 6, Akzo says.

Himont is supplementing its nonhalogen intumescent line with new Spinflam MB 92/PP, a "low-halogen" product containing ammonium bromide, a non-aromatic compound that's said to produce low smoke and no corrosive gases. This free-flowing powder is a complete package already containing antimony oxide. It's aimed at PP seating, electrical parts, pipe and fittings. Suggested loadings for UL 94V-2 flammability are 4-5% for homopolymers and up to 8% for copolymers.

Great Lakes Chemical has been quietly offering for three years an unusual product called DP-45, a fully brominated form of DOP, which is used as a plasticizer for PVC wire and cable.

Another relatively new product from Great Lakes for PVC is FR-756, a disodium salt of tetrabromobisphenol-A (TBBPA). In Europe, it's used in calendering.

There's also FM-200, an HCFC that Great Lakes associate v.p. Charles Ludwig says shows good flame retardancy as a blowing agent in urethane foams, and has zero ozone-depletion potential. However, it's currently expensive (around $10/lb), though the price could drop with larger volume usage.

Great Lakes is looking to develop new uses for its reactive TBBPA carbonate oligomers. These low-molecular-weight brominated polycarbonates are already used in PBT and are starting to move into ABS and HIPS. Ludwig says they act as flow enhancers and as compatibilizers of blends like ABS/PVC. He concedes that they're a bit on the expensive side, at around $2.25-2.40/lb, and use levels are on the order of 14%. However, he notes that they have advantages of higher efficiency and uv stability than brominated epoxy oligomers.

Meanwhile, a new series of brominated epoxies has been fielded by Dead Sea Bromine (contact AtoHaas in this country). The F-2000 FR series of polymers and oligomers ranges in molecular weight from 700 to 50,000 and includes reactive and nonreactive types for use in epoxy, phenolic, unsaturated polyester, ABS, HIPS, alloys (PC/ABS), nylon 6 and 66, PET, PBT, and TPU. They're said to be nonblooming and to offer good uv and thermal stability. The main application to date is ABS, where it is said to be a more economical replacement for octabromodiphenyl oxide. The company is seeking a patent on a mixture of a brominated epoxy, TBBPA (Dead Sea's FR-1524), and a special impact modifier.

Also new is FR-42063G, a patented mixture based on the company's FR-1206 hexabromocyclododecane. It's use is said to be growing fast in Europe for extruded PS foams where CFCs have been replaced by pentane. It is thermally stable and contains a component that sublimes to a gas within the foam cells, helping to counteract the flammability of the pentane.

Dead Sea Bromine is also working on an FR masterbatch to be produced by grafting its reactive Actimer FR-1025M (pentabromobenzyl acrylate) onto ABS.