Flame retardant heavily filled thermoplastic composition

A composition which comprises:

• (a) from about 20 to about 90 weight percent of a single thermoplastic resin or a heteropolymer thermoplastic resin blend;
• (b) from about 20 to about 80 weight percent of an inorganic filler selected from the group consisting of barium sulfate, strontium sulfate, zirconium oxide and zinc sulfate;
• (c) an effective flame retarding amount of a metal acid pyrophosphate of the formula:
• M.sup.z.sub.x H.sub.y P.sub.n O.sub.3n+1
• wherein M is a metal selected from the group consisting of alkali metals and alkaline earth metals, x is a number from 1 to 12, y is a number from 1 to 12, n is a number from 2 to 10, z is a number from 1 to 5, and the sum of (xz)+y is equal to n+2;
• (d) from an effective amount to about 25 weight percent of a second flame retardant;
• said second flame retardant being a brominated flame retardant wherein said composition is characterized by the absence of an antimony compound as a synergist for said brominated flame retardant wherein said metal acid pyrophosphate and said halogenated flame retardant are present in an effective amount to render sufficient flame retardancy to said composition wherein said composition receives a VO rating under Underwriters Laboratory test No. 94;
• (e) an effective amount of a stabilizer selected from phosphites, acidic phosphate salts, phosphate salts of Group IB or Group IIB metal and phosphorous oxo-acids;
• and
• (f) from about 1 to about 30 percent of an impact modifier, all percentages being based on the weight of the total composition.

A composition consisting essentially of:

• (a) from 20-65 weight percent of a single polyester resin or a blend of polyester resins:
• (b) from 25-65 weight percent of a brominated polycarbonate;
• (c) from 5-20 weight percent of a metal acid pyrophosphate;
• (d) from 1-45 weight percent of a rubbery impact modifier;
• and
• (e) from 0.1-5 weight percent of a stabilizer.

A flame retardant thermoplastic resin composition consisting essentially of:

• (a) from about 20 to about 90 weight percent of a thermoplastic resin;
• (b) from about 20 to about 80 weight percent of an inorganic filler;
• and
• (c) an effective flame retarding amount of a metal acid pyrophosphate
• (d) a halogenated flame retardant wherein said composition is characterized by the absence of an antimony compound as a synergist for said halogenated flame retardant wherein said metal acid pyrophosphate and said halogenated flame retardant are present in an effective amount to render sufficient flame retardancy to said composition wherein said composition receives a VO rating under Underwriters Laboratory test No. 94.