Flash-spinning polymeric plexifilaments

Claim 2

An improved process for flash-spinning plexifilamentary film-fibril strands wherein polyethylene is dissolved in a hydrocarbon/co-solvent spin liquid to form a spin mixture containing 8 to 35 percent of polyethylene by weight of the spin mixture at a temperature in the range of 130° to 300° C. and a mixing pressure that is greater than 1500 psig, which spin mixture is flash-spun at a spin pressure greater than 1500 psig into a region of substantially lower temperature and pressure, the improvement comprising the hydrocarbor/co-solvent spin liquid consisting essentially of a hydrocarbon spin liquid containing from 4 to 5 carbon atoms and having an atmospheric boiling point less than 45° C. and a co-solvent spin liquid having an atmospheric boiling point less than 100° C. and capable of raising the cloud-point pressure of the resulting spin mixture by at least 200 psig at the polyethylene concentration and the spin temperature used for flash-spinning, the co-solvent spin liquid being present in an amount greater than 10 percent by weight of the total hydrocarbon/co-solvent spin liquid present.

Claim 3

The improved process of claim 1 wherein the hydrocarbon spin liquid is selected from the group consisting of isobutane, butane, cyclobutane, 2-methyl butane, 2,2-dimethyl propane, pentane, methyl cyclobutane and mixtures thereof.

Claim 4

An improved process for flash-spinning plexifilamentary film-fibril strands wherein polyethylene is dissolved in a hydrocarbon/co-solvent spin liquid to form a spin mixture containing 8 to 35 percent of polyethylene by weight of the spin mixture at a temperature in the range of 130° to 300° C. and a mixing pressure that is greater than 700 psig, which spin mixture is flash-spun at a spin pressure greater than 700 psig into a region of substantially lower temperature and pressure, the improvement comprising the hydrocarbon/co-solvent spin liquid consisting essentially of a hydrocarbon spin liquid containing from 5 to 7 carbon atoms and having an atmospheric boiling point between 45° C. to 100° C. and a co-solvent spin liquid having an atmospheric boiling point less than 100° C. and capable of raising the cloud-point pressure of the resulting spin mixture by at least 200 psig at the polyethylene concentration and the spin temperature used for flash-spinning, the co-solvent spin liquid being present in an amount greater than 10 percent by weight of the total hydrocarbon/co-solvent spin liquid present.

Claim 5

An improved process for flash-spinning plexifilamentary film-fibril strands wherein polyethylene is dissolved in a hydrocarbon/co-solvent spin liquid to form a spin mixture containing 8 to 35 percent of polyethylene by weight of the spin mixture at a temperature in the range of 130° to 300° C. and a mixing pressure that is greater than 700 psig, which spin mixture is flash-spun at a spin pressure greater than 700 psig into a region of substantially lower temperature and pressure, the improvement comprising the hydrocarbon/co-solvent spin liquid consisting essentially of a hydrocarbon spin liquid containing from 5 to 7 carbon atoms and having an atmospheric boiling point between 45° C. to 100° C. and a co-solvent spin liquid having an atmospheric boiling point less than 100° C. and capable of raising the cloud-point pressure of the resulting spin mixture by at least 200 psig at the polyethylene concentration and the spin temperature used for flash-spinning, the co-solvent spin liquid being present in an amount greater than 10 percent by weight of the total hydrocarbon/co-solvent spin liquid present.

Claim 6

The improved process of claim 3 wherein the hydrocarbon spin liquid is selected from the group consisting of cyclopentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methylpentane,3-methylpentane, hexane, methyl cyclopentane, cyclohexane, 2-methyl hexane, 3-methyl hexane, heptane and mixtures thereof.

Claim 7

The improved process of claims 1 or 3 wherein the co-solvent spin liquid is selected from the group consisting of inert gases, hydrofluorocarbons, hydrochlorofluorocarbons, perfluorinated hydrocarbons, polar solvents and mixtures thereof.

Claim 8

The improved process of claims 1 or 3 wherein the co-solvent spin liquid has an atmospheric boiling point between -100° C. and 100° C.

Claim 9

The improved process of claim 5 wherein the inert gas is carbon dioxide.

Claim 10

The improved process of claim 5 wherein the hydrofluorocarbon is selected from the group consisting of pentafluoroethane, 1,1,1,2-tetrafluoroethane, 1,1-difluoroethane and their isomers.

Claim 11

The improved process of claim 5 wherein the polar solvent is selected from the group consisting of methanol, ethanol, propanol, isopropanol, 2-butanone and tert-butyl alcohol.

Claim 12

The improved process of claims 1 or 3 wherein the co-solvent spin liquid raises the cloud-point pressure of the spin mixture by at least 500 psig at the polyethylene concentration and the spin temperature used for flash-spinning.

Claim 13

An improved process for flash-spinning plexifilamentary film-fibril strands wherein polyethylene, having a melt index of less than 4 and a density of between 0.92-0.98, is dissolved in a hydrocarbon/co-solvent spin liquid consisting essentially of 60 to 90 wt. % pentane and 10 to 40 wt. % methanol to form a spin mixture containing 8 to 35 percent of polyethylene by weight of the spin mixture at a temperature in the range of 130° to 300° C. and a mixing pressure that is greater than 1500 psig, which solution is flash-spun at a spin pressure greater than 1500 psig into a region of substantially lower temperature and pressure.

Claim 14

An improved process for flash-spinning plexifilamentary film-fibril strands wherein polyethylene, having a melt index of less than 4 and a density of between 0.92-0.98, is dissolved in a hydrocarbon/co-solvent spin liquid consisting essentially of 60 to 90 wt. % pentane and 10 to 40 wt. % methanol to form a spin mixture containing 8 to 35 percent of polyethylene by weight of the spin mixture at a temperature in the range of 130° to 300° C. and a mixing pressure that is greater than 1500 psig, which solution is flash-spun at a spin pressure greater than 1500 psig into a region of substantially lower temperature and pressure.

Claim 15

An improved process for flash-spinning plexifilamentary film-fibril strands wherein polypropylene is dissolved in a hydrocarbon/co-solvent spin liquid to form a spin mixture containing 8 to 30 percent of polypropylene by weight of the spin mixture at a temperature in the range of 150° to 250° C. and a mixing pressure that is greater than 700 psig, which spin mixture is flash-spun at a spin pressure greater than 700 psig into a region of substantially lower temperature and pressure, the improvement comprising the hydrocarbon/co-solvent spin liquid consisting essentially of a hydrocarbon spin liquid containing from 4 to 7 carbon atoms and having an atmospheric boiling point less than 100° C. and a co-solvent spin liquid having an atmospheric boiling point less than 100° C. and capable of raising the cloud-point pressure of the resulting spin mixture by at least 200 psig at the polypropylene concentration and the spin temperature used for flash-spinning, the co-solvent spin liquid being present in an amount greater than 10 weight percent of the total hydrocarbon/co-solvent spin liquid present.

Claim 16

An improved process for flash-spinning plexifilamentary film-fibril strands wherein polypropylene is dissolved in a hydrocarbon/co-solvent spin liquid to form a spin mixture containing 8 to 30 percent of polypropylene by weight of the spin mixture at a temperature in the range of 150° to 250° C. and a mixing pressure that is greater than 700 psig, which spin mixture is flash-spun at a spin pressure greater than 700 psig into a region of substantially lower temperature and pressure, the improvement comprising the hydrocarbon/co-solvent spin liquid consisting essentially of a hydrocarbon spin liquid containing from 4 to 7 carbon atoms and having an atmospheric boiling point less than 100° C. and a co-solvent spin liquid having an atmospheric boiling point less than 100° C. and capable of raising the cloud-point pressure of the resulting spin mixture by at least 200 psig at the polypropylene concentration and the spin temperature used for flash-spinning, the co-solvent spin liquid being present in an amount greater than 10 weight percent of the total hydrocarbon/co-solvent spin liquid present.

Claim 17

The improved process of claim 12 wherein the hydrocarbon spin liquid is selected from the group consisting of isobutane, butane, cyclobutane, 2-methyl butane, 2,2-dimethyl propane, pentane, methyl cyclobutane, cyclopentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methylpentane, 3-methylpentane, hexane, methyl cyclopentane, cyclohexane, 2-methyl hexane, 3-methyl hexane, heptane and mixtures thereof.

Claim 18

The improved process of claim 12 wherein the co-solvent spin liquid is selected from the group consisting of inert gases, hydrofluorocarbons, hydrochlorofluorocarbons, perfluorinated hydrocarbons, polar solvents and mixtures thereof.

Claim 19

The improved process of claim 12 wherein the co-solvent spin liquid has an atmospheric boiling point between -100° C. and 100° C.

Claim 20

The improved process of claim 14 wherein the inert gas is carbon dioxide.

Claim 21

The improved process of claim 14 wherein the hydrofluorocarbon is selected from the group consisting of pentafluoroethane, 1,1,1,2-tetrafluoroethane, 1,1-difluoroethane and their isomers.

Claim 22

The improved process of claim 14 wherein the polar solvent is selected from the group consisting of methanol, ethanol, propanol, isopropanol, 2-butanone and tert-butyl alcohol.

Claim 23

The improved process of claim 12 wherein the co-solvent spin liquid raises the cloud-point pressure of the spin mixture by at least 500 psig at the polypropylene concentration and the spin temperature used for flash-spinning.