Ignition resistant polycarbonate polyester composition

1 . A thermoplastic composition comprising:

(a) structural units derived from at least one substituted or unsubstituted polycarbonate;

(b) a polyester comprising structural units is derived from xylene glycol;

(c) from 1 weight percent to about 40 weight percent based on the total weight of the composition of a flame retardant compound,

wherein the composition is transparent, and

wherein the components (a), (b) and (c) are in sufficient amounts to make the composition ignition resistant.

2 . The composition of claim 1 , wherein the polycarbonate comprises repeating units of the formula:

wherein R is a divalent aromatic radical derived from a dihydroxyaromatic compound of the formula HO-D-OH, wherein D has the structure of formula:

wherein A 1 represents an aromatic group; E comprises a sulfur-containing linkage, sulfide, sulfoxide, sulfone; a phosphorus-containing linkage, phosphinyl, phosphonyl; an ether linkage; a carbonyl group; a tertiary nitrogen group; a silicon-containing linkage; silane; siloxy; a cycloaliphatic group; cyclopentylidene, cyclohexylidene, 3,3,5-trimethylcyclohexylidene, methylcyclohexylidene, 2-[2.2.1]-bicycloheptylidene, neopentylidene, cyclopentadecylidene, cyclododecylidene, adamantylidene; an alkylene or alkylidene group, which group may optionally be part of one or more fused rings attached to one or more aromatic groups bearing one hydroxy substituent; an unsaturated alkylidene group; or two or more alkylene or alkylidene groups connected by a moiety different from alkylene or alkylidene and selected from the group consisting of an aromatic linkage, a tertiary nitrogen linkage; an ether linkage; a carbonyl linkage; a silicon-containing linkage, silane, siloxy; a sulfur-containing linkage, sulfide, sulfoxide, sulfone; a phosphorus-containing linkage, phosphinyl, and phosphonyl;

R 1 independently at each occurrence comprises a mono-valent hydrocarbon group, aliphatic, aromatic, or a cycloaliphatic radical;

Y 1 independently at each occurrence is selected from the group consisting of an inorganic atom, a halogen; an inorganic group, a nitro group; an organic group, a monovalent hydrocarbon group, alkenyl, allyl, alkyl, aryl, aralkyl, alkaryl, cycloalkyl, and an alkoxy group;

the letter “m” represents any integer from and including zero through the number of replaceable hydrogens on A 1 available for substitution;

the letter “p” represents an integer from and including zero through the number of replaceable hydrogens on E available for substitution;

the letter “t” represents an integer equal to at least one;

the letter “s” represents an integer equal to either zero or one; and

“u” represents any integer including zero.

3 . The composition of claim 2 , wherein the dihydroxyaromatic compound from which D is derived is bisphenol A.

4 . The composition of claim 1 , wherein the polyester is derived from structural units comprising at least one substituted or unsubstituted diacid and xylene glycol.

5 . The composition of claim 4 , wherein the diacid is selected from the group consisting of linear acids, terephthalic acids, isophthalic acids, phthalic acids, naphthalic acids, cycloaliphatic acids, bicyclo aliphatic acids, decahydro naphthalene dicarboxylic acids, norbornene dicarboxylic acids, bicyclo octane dicarboxylic acids, 1,4-cyclohexanedicarboxylic acid, adipic acid, azelaic acid, dicarboxyl dodecanoic acid, stilbene dicarboxylic acid, succinic acid, chemical equivalents of the foregoing, and combinations thereof.

6 . The composition of claim 1 , wherein the xylene glycol is selected from the group consisting of para-xylene glycol, ortho-xylene glycol, meta-xylene glycol and mixtures thereof.

7 . The composition of claim 1 , wherein the xylene glycol is in an amount ranging from about 15 mole percent to about 100 mole percent.

8 . The composition of claim 6 , wherein the xylene glycol is para-xylene glycol.

9 . The composition of claim 1 , wherein the polyester further comprises structural units derived from a diol selected from the group consisting of ethylene glycol;

propylene glycol, butanediol, pentane diol; dipropylene glycol; 2-methyl-1,5-pentane diol; 1,6-hexane diol; decalin dimethanol, bicyclo octane dimethanol; 1,4-cyclohexane dimethanol; triethylene glycol; 1,10-decane diol; tricyclodecane dimethanol; hydrogenated bisphenol-A, tetramethyl cyclobutane diol, chemical equivalents of the foregoing, and combinations thereof.

10 . The composition of claim 1 , wherein the polyester is present in an amount ranging from about 10 to about 90 weight percent, based on the total weight of the composition.

11 . The composition of claim 1 , wherein the polyester is present in an amount ranging from about 25 to about 75 weight percent, based on the total weight of the composition.

12 . The composition of claim 1 , wherein the polycarbonate is present ranging about 90 to about 10 weight percent, based on the total weight of the composition.

13 . The composition of claim 1 , wherein the polycarbonate is present ranging from about 75 to about 25 weight percent, based on the total weight of the composition.

14 . The composition of claim 1 , wherein the flame retardant compound is selected from the group consisting of brominated flame-retardants, phosphorus containing compounds and combinations thereof.

15 . The composition of claim 1 , wherein the flame retardant is present ranging from about 5 weight percent to about 30 weight percent, based on the amount of the total composition.

16 . The composition of claim 1 , wherein the composition further comprises an additive.

17 . The composition of claim 16 , wherein the additive is selected from the group consisting of anti-oxidants, flow modifiers, impact modifiers, colorants, mold release agents, UV light stabilizers, heat stabilizers, lubricants, anti-drip agents and combinations thereof.

18 . The composition of claim 16 , wherein the additive is present ranging from about 0 to 1.5 weight percent, based on the total weight of the thermoplastic resin.

19 . The composition of claim 1 , wherein the composition has an intrinsic viscosity of at least greater than about 0.55 dL/g.

20 . The composition of claim 1 , wherein the composition has a glass transition temperature in the range between about 40° C. and about 130° C.

21 . The composition of claim 1 , wherein the composition has a char yield of at least greater than about 4%.

22 . The composition of claim 1 , wherein the composition transmits about greater than 60 percent light in the region of about 400 nm to about 800 nm.

23 . The composition of claim 1 , wherein the composition is resistant to deterioration from contact with organic alcohols.

24 . An article molded from the composition of claim 1 .

25 . A process to prepare an ignition resistant thermoplastic composition comprising:

(a) structural units derived from at least one substituted or unsubstituted polycarbonate;

(b) a polyester comprising structural units is derived from xylene glycol;

(c) from 1 weight percent to about 40 weight percent based on the total weight of the composition of a flame retardant compound;

wherein the composition is transparent and wherein the process comprises the steps of:

i. mixing the polycarbonate and polyester to form a first mixture; and

ii. heating the first mixture to form the transparent composition.

26 . The process of claim 25 , wherein the process is carried out in presence of a catalyst.

27 . The process of claim 26 , wherein the catalyst is selected from the group consisting of alkali metal and alkaline earth metal salts of aromatic dicarboxylic acids, alkali metal and alkaline earth metal salts of aliphatic dicarboxylic acids, Lewis acids, metal oxides, coordination complexes of the foregoing and combinations thereof.

28 . The process of claim 25 , wherein the process is carried out in presence of a solvent.

29 . A thermoplastic composition comprising:

(a) structural units derived from at least one substituted or unsubstituted polycarbonate;

(b) a polyester comprising structural units is derived from xylene glycol;

(c) from 1 weight percent to about 40 weight percent based on the total weight of the composition of a flame retardant compound; wherein the flame retardant compound is at least one selected from the group consisting of brominated flame retardants and phosphorus containing compounds;

wherein the composition is transparent and wherein the components (a), (b) and (c) are in sufficient amounts to make the composition ignition resistant.