Impact-modified polyalkylene terephthalate/polycarbonate compositions

1. A concentrate comprising:

C.1) from 98 wt. % to 70 wt. % (based on the sum of the wt. % of C.1)+C.2)) of polyalkylene terephthalate or a mixture of at least two polyalkylene terephthalates and

C.2) from 2 wt. % to 30 wt. % (based on the sum of the wt. % of C.1)+C.2)) of at least one compound selected from the group consisting of

C.2.1) the compound of formula (IV)

HO 2 C—CH 2 —CH 2 —P(═O)(OH) 2   (IV)

C.2.2) the compound of formula (V)

C.2.3) the compound of formula (VI)

C.2.4) ortho-phosphoric acid H 3 PO 4 (VII)

C.2.5) the compound of formula (VIII)

and

C.2.6) phosphorous acid H 3 PO 3 (IX).

2. A concentrate according to claim 1 comprising from 93 wt. % to 80 wt. % (based on the sum of the wt. % of C.1)+C.2)) of component C.1) and from 7 wt. % to 20 wt. % (based on the sum of the wt. % of C.1)+C.2)) of component C.2).

3. A composition comprising

A) aromatic polycarbonate,

B) polyalkylene terephthalate and

C) a concentrate according to claim 1 .

4. A composition according to claim 3 comprising

A) from 29.8 to 82.8 parts by weight (in each case based on the sum of the parts by weight of components A+B+C) of aromatic polycarbonate,

B) from 15 to 70 parts by weight (in each case based on the sum of the parts by weight of components A+B+C) of polyalkylene terephthalate,

C) from 0.2 to 5 parts by weight (in each case based on the sum of the parts by weight of components A+B+C) of said concentrate,

D) from 0 to 40 parts by weight (in each case based on the sum of the parts by weight of components A+B+C) of rubber-modified graft polymer and

E) from 0 to 20 parts by weight (based on the sum of the parts by weight of components A+B+C=100) of an additive.

5. A composition according to claim 4 comprising

A) from 39.5 to 89.5 parts by weight (in each case based on the sum of the parts by weight of components A+B+C) of aromatic polycarbonate,

B) from 25 to 55 parts by weight (in each case based on the sum of the parts by weight of components A+B+C) of polyalkylene terephthalate,

C) from 0.7 to 2 parts by weight (in each case based on the sum of the parts by weight of components A+B+C) of said concentrate,

D) from 8 to 18 parts by weight (in each case based on the sum of the parts by weight of components A+B+C) of rubber-modified graft polymer and

E) from 1 to 15 parts by weight (based on the sum of the parts by weight of components A+B+C=100) of said additive.

6. A composition according to claim 3 , comprising as component B polybutylene terephthalate.

7. A process for the preparation of a polycarbonate/polyalkylene terephthalate composition having improved melt stability, said process comprising:

(i) in the first step preparing a concentrate, wherein

(1-1) the components

C.1) from 98 wt. % to 70 wt. % (based on the sum of the wt. % of C.1)+C.2)) of a melt of polyalkylene terephthalate and

C.2) from 2 wt. % to 30 wt. % (based on the sum of the wt. % of C.1)+C.2)) of at least one compound selected from the group consisting of ortho-phosphoric acid, phosphorous acid, carboxylic acid esters of ortho-phosphoric acid and carboxylic acid esters of phosphorous acid, component C.2) being used in the form of a solid or in liquid form,

are mixed, and

(1-2) the resulting mixture is then melt extruded and

(ii) in a second step

(ii-1) the following constituents

A) from 29.8 to 82.8 parts by weight (in each case based on the sum of the parts by weight of components A+B+C) of aromatic polycarbonate,

B) from 15 to 70 parts by weight (in each case based on the sum of the parts by weight of components A+B+C) of polyalkylene terephthalate,

C) from 0.2 to 5 parts by weight (in each case based on the sum of the parts by weight of components A+B+C) of the concentrate prepared according to step (i),

D) from 0 to 40 parts by weight (in each case based on the sum of the parts by weight of components A+B+C) of rubber-modified graft polymer and

E) from 0 to 50 parts by weight (in each case based on the sum of the parts by weight of components A+B+C=100) of additives

are mixed, and

(ii-2) melt compounded, optionally at a temperature of from 200° C. to 320° C., and

(ii-3) are then melt extruded.

8. A process according to claim 7 , wherein, in step (i-2) the resulting mixture is cooled to a temperature of from −20° C. to 100° C., so that the mixture is obtained in solid form.

9. A process according to claim 7 , wherein there is used as component B polybutylene terephthalate.

10. A method for improving melt stability of a composition comprising aromatic polycarbonate and polyalkylene terephthalate comprising employing a concentrate according to claim 1 in said composition.

11. A method for production of mouldings or semi-finished products comprising utilizing a composition of claim 3 .

12. A moulded body comprising a composition according to claim 3 .

13. A composition comprising:

A) from 29.8 to 82.8 parts by weight (in each case based on the sum of the parts by weight of components A+B+C) of aromatic polycarbonate,

B) from 15 to 70 parts by weight (in each case based on the sum of the parts by weight of components A+B+C) of polyalkylene terephthalate,

C) from 0.2 to 5 parts by weight (in each case based on the sum of the parts by weight of components A+B+C) of a concentrate comprising:

C.1) from 98 wt. % to 70 wt. % (based on the sum of the wt. % of C.1)+C.2)) of polyalkylene terephthalate or a mixture of at least two polyalkylene terephthalates and

C.2) from 2 wt. % to 30 wt. % (based on the sum of the wt. % of C.1)+C.2)) of at least one compound selected from the group consisting of ortho-phosphoric acid, phosphorous acid, carboxylic acid esters of ortho-phosphoric acid and carboxylic acid esters of phosphorous acid,

D) from 0 to 40 parts by weight (in each case based on the sum of the parts by weight of components A+B+C) of rubber-modified graft polymer, and

E) from 0 to 20 parts by weight (based on the sum of the parts by weight of components A+B+C=100) of an additive.

14. The concentrate of claim 1 , wherein (C.2) is the compound of formula (IV)

HO 2 C—CH 2 —CH 2 —P(═O)(OH) 2   (IV).

15. The concentrate of claim 1 , wherein (C.2) is the compound of formula (V).

16. The concentrate of claim 1 , wherein (C.2) is the compound of formula (VI)

17. The concentrate of claim 1 , wherein (C.2) is ortho-phosphoric acid H 3 PO 4 .

18. The concentrate of claim 1 , wherein (C.2) is the compound of formula (VII)

19. The concentrate of claim 1 , wherein (C.2) is phosphorous acid H 2 PO 3 .