Flash spinning process

Patent metadata

Field	Value
Publication number	US-12024799-B2
Application number	US-202217581233-A
Country	US
Kind code	B2
Filing date	Jan 21, 2022
Priority date	Jun 11, 2015
Publication date	Jul 2, 2024
Grant date	Jul 2, 2024

Abstract

A process for the preparation of plexifilamentary film-fibril strands of polymer. The process includes the steps of generating a spin fluid containing (a) 5 to 30 wt. % containing one or more polymer types, (b) a primary spin agent selected from the group consisting of dichloromethane, cis-1,2-dichloroethylene and trans-1,2-dichloroethylene, and (c) a co-spin agent comprising 1H,6H-perfluorohexane or 1H-perfluorohexane or 1H-perfluoroheptane. The spin fluid is flash-spun 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 polymer. The co-spin agent is present in the spin fluid in an amount sufficient to form an azeotrope-like composition with the primary spin agent in the presence of the one or more polymer types. The polymer may be selected from the group consisting of high density polyethylene, polypropylene, polybutene-1, polymethylpentene, polyvinylidene fluoride, poly (ethylene tetrafluoroethylene), and blends of the foregoing.

First claim

The invention claimed is:

1. A spin fluid comprising a spin agent composition and a polymer
in an amount of 5 to 30 weight percent of total spin fluid,
wherein said polymer consists of polyethylene, and
wherein said spin fluid is utilized in a process of flash-spinning fibers and the spin agent is a non-solvent to the polymer below the spin agent's atmospheric pressure boiling point,
wherein the spin agent composition comprises
(a) a primary spin agent that is dichloromethane, cis-1,2-dichloroethylene, or trans-1,2-dichloroethylene, and
(b) a co-spin agent that is 1H,6H-perfluorohexane 1H-perfluoroheptane or 1H-perfluorohexane,

wherein the co-spin agent is present in an amount sufficient to form an azeotrope or azeotrope-like composition with the primary spin agent in the spin fluid, wherein the azeotropic or azeotrope like compositions are determined at 40° C., and wherein the azeotrope-like composition is the composition of fluids wherein the boiling point pressure is different by less than 5% from the dew point pressure.

2. The spin fluid of claim 1 , wherein said flash-spinning process comprises 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 polymer.

3. A method for preparing a spin according to claim 1 ,
wherein said polymer consists of polyethylene, and
wherein said spin fluid is utilized in a process of flash-spinning fibers and the spin agent is a non-solvent to the polymer below the spin agent's atmospheric pressure boiling point,
the method comprising combining
(a) a primary spin agent that is dichloromethane, cis-1,2-dichloroethylene, or trans-1,2-dichloroethylene,
(b) a co-spin agent that is 1H6H-perfluorohexane, 1H-perfluoroheptane, or 1H-perfluorohexane, in an amount sufficient to form an azeotrope or azeotrope-like composition with the primary spin agent in the spin fluid, and
(c) a said polymer in an amount of 5 to 30 weight percent of total spin fluid, wherein the azeotropic or azeotrope like compositions are determined at 40° C., and wherein the azeotrope-like composition is the composition of fluids wherein the boiling point pressure is different by less than 5% from the dew point pressure.

4. The method of claim 3 , wherein said flash-spinning process comprises 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 polymer.

5. A spin fluid comprising a spin agent composition and a polymer in an amount of 5 to 30 weight percent of total spin fluid,
wherein said polymer consists of polyethylene, and
wherein said spin fluid is utilized in a process of flash-spinning fibers and the spin agent is a non-solvent to the polymer below the spin agent's atmospheric pressure boiling point,
wherein the spin agent composition comprises
(a) a primary spin agent is dichloromethane, cis-1,2-dichloroethylene, or trans-1,2-dichloroethylene, and
(b) a co-spin agent that is 1H,6H-perfluorohexane, 1H-perfluoroheptane, or 1H-perfluorohexane,

wherein the co-spin agent is present in an amount sufficient to form a cloud point, wherein the cloud point is the pressure and temperature at which a clear single phase spin fluid separates into two phases and becomes turbid, the cloud point being determined at each temperature by supplying the clear single phase spin fluid to a pressurized view cell assembly containing a sight glass, monitoring the pressure and temperature of the spin fluid in the view cell as applied pressure is decreased until a second phase is formed in the view cell behind the sight glass, as evidenced by cloudiness of the once clear single phase spin fluid.

6. The spin fluid of claim 5 , wherein said flash-spinning process comprises 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 polymer.

7. A method for preparing a spin fluid according to claim 5 ,
wherein said polymer consists of polyethylene, and
wherein said spin fluid is utilized in a process of flash-spinning fibers and the spin agent is a non-solvent to the polymer below the spin agent's atmospheric pressure boiling point,
the method comprising combining
(a) a primary spin agent is dichloromethane, cis-1,2-dichloroethylene, or trans-1,2-dichloroethylene,
(b) a co-spin agent is 1H,6H-perfluorohexane, 1H-perfluoroheptane, or 1H-perfluorohexane, in an amount sufficient to form a cloud point, and
(c) said polymer of one or more polymer types in an amount of 5 to 30 weight percent of total spin fluid,

wherein the cloud point is the pressure and temperature at which a clear single phase spin fluid separates into two phases and becomes turbid, the cloud point being determined at each temperature by supplying the clear single phase spin fluid to a pressurized view cell assembly containing a sight glass, monitoring the pressure and temperature of the spin fluid in the view cell as the applied pressure is decreased until a second phase is formed in the view cell behind the sight glass, as evidenced by cloudiness of the once clear single phase spin fluid.

8. The method of claim 7 , wherein said flash-spinning process comprises 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 polymer.

Assignees

• Dupont Safety & Construction Inc

Inventors

• Schmitz Corneille
• Van Meerveld Jan
• Skoplyak Orest
• Rebouillat Serge

Classifications

• D01F6/04 Primary

  from polyolefins · CPC title

• D01F1/10

  Other agents for modifying properties · CPC title

• D01D11/00

  Other features of manufacture · CPC title

• D01D1/02

  Preparation of spinning solutions · CPC title

• D01D5/11 Primary

  Flash-spinning · CPC title