Process for removing residual spin solvent from a gel spun filament, the filament, multi-filament yarn and products comprising the filament

Abstract

Processes for removing residual spin solvent from a gel spun, UHMwPE filament having an effective diameter of above 16 μm, comprise the steps of removing residual spin solvent from the filament to a level of below 100 ppm at elevated temperature, while keeping the filament taut. Gel spun UHMwPE filaments having an effective diameter of above 16 μm and a residual spin solvent residue of less than 100 ppm are also provided. Preferably the filament has a creep rate, measured at 50° C., under a load, so that the initial stress is 600 MPa, of less than 5·10⁻⁶ sec⁻¹.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation of commonly owned U.S. Ser. No. 12 / 593,469, filed Dec. 7, 2009, (now U.S. Pat. No. 9,260,801), which is the national phase application under 35 USC §371 of PCT / EP2008 / 002298, filed Mar. 21, 2008, which designated the U.S. and claims priority to European Application No. 07006238.5, filed Mar. 27, 2007, the entire contents of each of which are hereby incorporated by reference.FIELD[0002]The invention relates to a process for removing residual spin solvent from a gel spun, ultra high molecular weight UHMwPE (UHMwPE) filament, the filament as well as a multi-filament yarn and products for medical applications containing the filament.BACKGROUND AND SUMMARY[0003]A process for producing gel spun, UHMwPE filaments is for example disclosed in PCT / NL2003 / 000872.[0004]It is also known to use gel spun, UHMwPE multi-filament yarn in products for medical applications. Examples of such products are sutures and cables. ...

AI Technical Summary

Benefits of technology

[0005]Special treatments to remove residual spin solvent include extended extraction or heating of the filament. Problems that occur because of such treatments are that filament properties are adversely affected, if a residual spin solvent level of at most 100 ppm is obtained, but even more if very low levels of residual spin solvent are obtained, below 80 ppm or even further down. This is especially true if filaments with a high diameter are used, since removal of solvents by extraction or evaporation becomes increasingly difficult with increasing diameter. However the use of filaments having a high diameter is advantageous, since such filaments are easier to produce. Furthermore, filaments having a high diameter are more robust during handling (for exa

Problems solved by technology

A gel spun filament however has the draw back that without special treatment it contains residual spin solvent.

Although the level of residual spin solvent normally is very low, it is still high enough to make the filament less suitable for use in medical applications like sutures and cables, since the residual spin solvent may cause unwanted reactions of the human or animal body, like for instance inflammations.

Problems that occur because of such treatments are that filament properties are adversely affected, if a residual spin solvent level of at most 100 ppm is obtained, but even more if very low levels of residual spin solvent are obtained, below 80 ppm or even further down.

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