Polymer processing aids

1. A polymer composition comprising a polymer matrix selected from the group consisting of polyamides, polyimides, polyurethanes, polyolefins, polystyrenes, polyesters, polycarbonates, polyketones, polyureas, polyvinyl resins, polyacrylates, polymethylacrylates and combinations thereof, a first fluorine-containing processing aid, and a second processing additive system that is substantially free of fluorine and that comprises: (a) a lubricant and (b) a surfactant comprising a polyolefin-block-polyalkylene oxide oligomer.

2. The composition of claim 1 , wherein the weight ratio of the first fluorine-containing processing aid to the second processing additive system is from 9:1 to 1:9.

3. The composition of claim 1 , wherein the first fluorine-containing processing aid is present in an amount of from 200 to 2,500 ppm of the polymer composition.

4. The composition of claim 1 , wherein the first fluorine-containing processing aid comprises a fluoropolymer.

5. The composition of claim 4 , wherein the fluoropolymer comprises a homo or copolymer derived from vinylidene fluoride, hexafluoropropylene, chlorotrifluoroethylene, tetrafluoroethylene, perfluoroalkyl perfluorovinyl ethers or mixtures thereof.

6. The composition of claim 1 , wherein the second processing additive system is present in an amount of from 200 to 2,500 ppm of the polymer composition.

7. The composition of claim 1 , wherein the lubricant of the second processing additive system comprises a polyalkylene oxide oligomer or polymer.

8. The composition of claim 7 , wherein the polyalkylene oxide oligomer or polymer has a molecular weight of from 2,000 to 50,000 g/mol.

9. The composition of claim 1 , wherein the surfactant of the second processing additive system comprises a polyethylene-block-polyalkylene oxide oligomer.

10. The composition of claim 9 , wherein the polyethylene-block-polyalkylene oxide oligomer has a molecular weight less than 5,000 g/mol.

11. The composition of claim 1 , wherein the weight ratio of the lubricant to the surfactant in the second processing additive system is from about 1:1 to about 6:1.

12. The composition of claim 1 , wherein the second processing additive system further comprises (c) an antioxidant in an amount between 0 and 20 wt % of the total weight of the second processing additive system.

13. A method of reducing melt defects produced during melt processing of a polymer matrix selected from the group consisting of polyamides, polyimides, polyurethanes, polyolefins, polystyrenes, polyesters, polycarbonates, polyketones, polyureas, polyvinyl resins, polyacrylates, polymethylacrylates and combinations thereof, the method comprising forming a blend of the polymer matrix with a first fluorine-containing processing aid, and a second processing additive system that is substantially free of fluorine and that comprises: (a) a lubricant and (b) a surfactant comprising a polyolefin-block-polyalkylene oxide oligomer.

14. The composition of claim 1 , wherein the first fluorine-containing processing aid is present in an amount of from 200 to 2,500 ppm of the polymer composition and the second processing additive system is present in an amount of from 200 to 2,500 ppm of the polymer composition.

15. The composition of claim 14 , wherein the first fluorine-containing processing aid comprises a fluoropolymer and the lubricant of the second processing additive system comprises a polyalkylene oxide oligomer or polymer having a molecular weight of from 2,000 to 50,000 g/mol.

16. The composition of claim 14 , wherein the weight ratio of the lubricant to the surfactant in the second processing additive system is from about 1:1 to about 6:1.

17. The composition of claim 13 , wherein the second processing additive system further comprises (c) an antioxidant in an amount between 0 and 20 wt % of the total weight of the second processing additive system.