Fluid polyester moulding masses

1. A thermoplastic molding composition comprising:

A) from 10 to 99.99% by weight of at least one thermoplastic polyester;

B) from 0.01 to 20% by weight of a hyperbranched polycarbonate having an OH number of from 1 to 600 mg KOH/g of polycarbonate (DIN 53240, Part 2), a degree of branching from 10 to 99.9%, and both structural and molecular non-uniformity;

C) from 0 to 60% by weight of other additives;

wherein the total of the percentages by weight of components A) to C) is 100%, wherein component B) has a glass transition temperature Tg of from −80° C. to 140° C.

2. The thermoplastic molding composition according to claim 1 , wherein component B) has a number-average molar mass Mn of from 100 to 15 000 g/mol.

3. The thermoplastic molding composition according to claim 1 , wherein component B) has a viscosity (mPas) at 23° C. (DIN 53019) of from 50 to 200 000.

4. The thermoplastic molding composition according to claim 1 , wherein B) has an OH number of from 10 to 550 mg KOH/g.

5. The thermoplastic molding composition according to claim 1 , wherein B) has an OH number of from 50 to 550 mg KOH/g.

6. The thermoplastic molding composition according to claim 1 , wherein the degree of branching of B) is from 20 to 99%.

7. The thermoplastic molding composition according to claim 1 , wherein the degree of branching of B) is from 20 to 95%.

8. The thermoplastic molding composition according to claim 1 , wherein the amount of B) is from 0.1 to 10% by weight.

9. The thermoplastic molding composition according to claim 1 , wherein component B) is obtainable via a process comprising:

reacting at least one organic carbonate (A) of the general formula RO[(CO)]nOR with at least one aliphatic, aliphatic/aromatic or aromatic alcohol (B) which has at least 3 OH groups, with elimination of alcohols ROH to give one or more condensates (K), where each R, independently of the others, is a straight-chain or branched aliphatic, aromatic/aliphatic or aromatic hydrocarbon radical having from 1 to 20 carbon atoms, and where the radicals R may also be connected to one another to form a ring, and n is an integer between 1 and 5, or

ab) reacting phosgene, diphosgene or triphosgene with abovementioned alcohol (B), with elimination of hydrogen chloride, and

intermolecular reaction of the condensates (K) to give a highly functional, highly branched, or highly functional, hyperbranched polycarbonate,

where the quantitative proportion of the OH groups to the carbonates in the reaction mixture is selected in such a way that the condensates (K) have an average of either one carbonate group and more than one OH group or one OH group and more than one carbonate group.

10. The thermoplastic molding composition according to claim 9 , wherein the reaction mixture further comprises at least one alcohol (B′) having two OH groups, with the proviso that the average total OH functionality of all of the alcohols used is greater than 2.

11. The thermoplastic molding composition according to claim 9 , where the resultant highly functional, highly branched, or highly functional, hyperbranched polycarbonate is reacted, in an additional step (step c)), with a suitable functionalizing reagent which can react with the OH and/or carbonate groups of the polycarbonate.

12. The thermoplastic molding composition according to claim 9 , where the highly functional, highly branched, or highly functional, hyperbranched polycarbonate is modified by carrying out step b) in the presence of additional compounds which have not only OH groups or carbonate groups but also other functional groups or functional elements.

13. A method of producing fibers, films, or moldings comprising utilizing the thermoplastic molding composition according to claim 1 .

14. A fiber, a film, or a molding obtainable from the thermoplastic molding compositions according to claim 1 .