Process for the Preparation of Polyolefin Fibers

Abstract

The present invention relates to a process for the preparation of polyolefin fibers having mean fiber diameters of less than 5000 nm, comprising the steps of: a) preparing a polyolefin solution in a solvent, b) placing said polyolefin solution in a fiber producing device comprising a body configured to receive said polyolefin solution, said body comprising one or more openings, and c) rotating the fiber producing device, wherein rotation of the fiber producing device causes the polyolefin solution to be passed through said one or more openings to produce polyolefin fibers having mean fiber diameters of less than 5000 nm, wherein said polyolefin is selected from the group comprising polyethylene polymers and copolymers having a weight average molecular weight Mw of at least 40 000 daltons, and polypropylene polymers and copolymers, having a weight average molecular weight Mw of at least 120 000 daltons; wherein said fiber producing device is rotated at a speed of at least 10 000 revolutions per minutes (RPM). The invention also relates to said polyolefin fibers, and to articles comprising said fibers.

Description

FIELD OF THE INVENTION[0001]The present invention relates to a process for the preparation of polyolefin fibers, preferably nanofibers, in particular for the preparation of polyethylene fibers. The present invention also relates to polyolefin fibers obtained therewith.BACKGROUND OF THE INVENTION[0002]There is a growing need for very fine fibers and fibrous webs made from very fine fibers. These types of webs are useful for selective barrier end uses. The nanofiber webs find use in a wide range of applications such as filtration, membrane separation, protective military clothing, biosensors, wound dressings, and scaffolds for tissue engineering. However, despite the potential mentioned above, the application of nanofibers has been limited due to its poor mechanical properties.[0003]Electrospinning and melt-blown spinning are the most widely used spinning methods to prepare polymeric fibers. Electrospinning is preferred for the nanosize fibers but this technic presents some drawbacks ...

AI Technical Summary

Benefits of technology

The process in this patent makes it possible to make polyolefin fibers with very small fiber diameters (less than 5,000 nm) and improved strength, flexibility, and durability.

Problems solved by technology

However, despite the potential mentioned above, the application of nanofibers has been limited due to its poor mechanical properties.

Electrospinning is preferred for the nanosize fibers but this technic presents some drawbacks such as the requirement for a high voltage electrical field, a low production rate and the requirement for precise solution conductivity.

To this day there is little or no success reported in making polymeric nanofibers, especially from polyolefin, such as polyethylene and polypropylene having good mechanical properties.

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