초록

A composition of tetrafluoroethylene/perfluoro(alkyl vinyl ether) having at least 4 wt % perfluoro(alkyl vinyl ether) and a melt flow rate of no greater than 4 g/10 min, and 5 to 30 wt % low molecular weight PTFE, has improved gas impermeability and also mechanical strength.

대표청구항 ▼

1. A melt-fabrication composition consisting essentially of a copolymer of tetrafluoroethylene and perfluoro(alkyl vinyl ether) (PFA) and about 5 to about 30 wt % of low molecular weight polytetrafluoroethylene (PTFE), based on the combined weight of the PFA and PTFE, wherein the low molecular weigh

1. A melt-fabrication composition consisting essentially of a copolymer of tetrafluoroethylene and perfluoro(alkyl vinyl ether) (PFA) and about 5 to about 30 wt % of low molecular weight polytetrafluoroethylene (PTFE), based on the combined weight of the PFA and PTFE, wherein the low molecular weight PTFE is characterized by a heat of crystallization of at least about 50 J/g and wherein the perfluoro(alkyl vinyl ether) content of the PFA is at least about 4 wt %, based on the total weight of the copolymer, and the PFA has a melt flow rate (MFR) of no more than about 4 g/10 min. 2. The composition of claim 1 wherein said perfluoro(alkyl vinyl ether) is perfluoro(ethyl vinyl ether). 3. The composition of claim 1 wherein said perfluoro(alkyl vinyl ether) is perfluoro(propyl vinyl ether). 4. The composition of claim 1 wherein the perfluoro(alkyl vinyl ether) content of the PFA is no more than 20 wt %. 5. The composition of claim 1 as a melt blend. 6. The composition of claim 5 wherein said melt blend has an increased flex life and reduced gas permeability as compared to said PFA alone. 7. An article for handling liquid consisting essentially of a copolymer of tetrafluoroethylene and perfluoro(alkyl vinyl ether) (PFA) and about 5 to about 30 wt % of low molecular weight polytetrafluoroethylene (PTFE), based on the combined weight of the PFA and PTFE, wherein the low molecular weight PTFE is characterized by a heat of crystallization of at least about 50 J/g and wherein the perfluoro(alkyl vinyl ether) content of the PFA is at least about 4 wt %, based on the total weight of the copolymer, and the PFA has a melt flow rate (MFR) of no more than about 4 g/10 min. 8. The article of claim 7 wherein said article is a vessel. 9. The article of claim 7 wherein said article is a tube.