Flash spinning solution and flash spinning process using straight chain hydrofluorocarbon co-solvents
View Patent ↗A spin fluid for producing plexifilamentary products made of a polyolefin dissolved in a primary solvent of dicloromethane or 1,2-dichloroethylene with a straight chain hydrofluorocarbon co-solvent.
1. A spin fluid comprising:
(a) 5 to 30 wt. % synthetic fiber-forming polyolefin,
(b) a primary solvent selected from the group consisting of dichloromethane and 1,2-dichloroethylene, and
(c) a co-solvent selected from the group consisting of straight chain hydrofluorocarbons having (i) 3 to 4 carbon atoms, (ii) an atmospheric boiling point between 10 and 50° C. and (iii) a molecular weight of less than 219, the co-solvent being present in the spin fluid in an amount sufficient to raise the cloud point pressure of the spin fluid by at least 50 pounds per square inch.
2. The spin fluid of claim 1 containing 10 to 20 wt. % synthetic fiber-forming polyolefin.
3. The spin fluid of claim 1 , wherein the co-solvent is selected from the group consisting of 1,1,1,3,3-pentafluoropropane, 1,1,2,2,3,3,4,4-octafluorobutane and 1,1,1,3,3-pentafluorobutane, and their isomers.
4. The spin fluid of claim 1 , wherein the synthetic fiber-forming polyolefin is selected from the group consisting of polyethylene, polypropylene, polymethylpentene, polyvinylidene fluoride, copolymer of ethylene and tetrafluoroethylene, and copolymer of ethylene and chlorotrifluoroethylene.
5. The spin fluid of claim 1 , wherein the synthetic fiber-forming polyolefin is polyethylene.
6. The spin fluid of claim 1 , wherein the synthetic fiber-forming polyolefin Is isotactic polypropylene.
7. The spin fluid of claim 1 , wherein the co-solvent is in an amount sufficient to raise the cloud point pressure of the spin fluid by at least 200 pounds per square inch.
8. A process for the preparation of plexifilamentary film-fibril strands of synthetic fiber-forming polyolefin which comprises:
generating a spin fluid of (a) 5 to 30 wt. % synthetic fiber-forming polyolefin, (b) a primary solvent selected from the group consisting of dichloromethane and 1,2-dichloroethylene, and (c) a co-solvent selected from the group consisting of straight chain hydrofluorocarbons having (i) 3 to 4 carbon atoms, (ii) an atmospheric boiling point between 10 and 50° C. and (iii) a molecular weight of less than 219, and the co-solvent being present in the spin fluid in a amount sufficient to raise the cloud point pressure of the spin fluid by at least 50 pounds per square inch, and flash-spinning the spin fluid at a pressure that is greater than the autogenous pressure of the spin fluid into a region of lower pressure to form plexifilamentary film-fibril strands of the synthetic fiber forming polyolefin.
9. The process of claim 8 , wherein the co-solvent is selected from the group consisting of 1,1,1,3,3-pentafluoropropane, 1,1,2,2,3,3,4,4-octafluorobutane and 1,1,1,3,3-pentafluorobutane, and their isomers.
10. The process of claim 8 , wherein the fiber-forming polyolefin is selected from the group consisting of polyethylene, polypropylene, polymethypentene, polyvinylidene flouride, copolymer of ethylene and tetrafluoroethylene, and copolymer of ethylene and chlorotrifluoroethylene.
11. The process of claim 8 , wherein the synthetic fiber-forming polyolefin is polypethylene.
12. The process of claim 8 , wherein the synthetic fiber-forming polyolefin is isotactic polypropylene.
13. The process of claim 8 , wherein the spin fluid contains 10 to 20 wt. % synthetic fiber-forming polyolefin.
14. The process of claim 8 , wherein the co-solvent is present in the spin fluid in an amount sufficient to raise the cloud point pressure of the spin fluid by at least 200 pounds per square inch.