CN-116745357-B - Low coefficient of friction polymer compositions

Abstract

The polymer composition comprises a vinyl polymer having a density of 0.926g/cc to 0.970g/cc as measured according to ASTM D792 and a polydimethylsiloxane having a weight average molecular weight of 550,000g/mol to 650,000g/mol as measured according to gel permeation chromatography. The composition is free of polydimethylsiloxane having a weight average molecular weight of 30,000g/mol to 300,000g/mol as measured by gel permeation chromatography.

Inventors

• P, J, Bree, Grundy
• M. Esgil
• S. A. Sabah
• A.K. Chowdhury

Assignees

• 陶氏环球技术有限责任公司

Dates

Publication Date

20260505

Application Date

20220126

Priority Date

20210202

Claims (11)

1. 1. A polymer composition, the polymer composition comprising: 80% by weight or more of a vinyl polymer having a density of 0.926g/cc to 0.970g/cc as measured according to ASTM D792, and 10% By weight or less of a polydimethylsiloxane having a weight average molecular weight of 550,000g/mol to 650,000g/mol as measured according to gel permeation chromatography, wherein the composition is free of a polydimethylsiloxane having a weight average molecular weight of 30,000g/mol to 300,000g/mol as measured according to gel permeation chromatography.
2. 2. The polymer composition of claim 1, wherein the polymer composition comprises 90 wt% or more of the vinyl polymer based on the total weight of the polymer composition.
3. 3. The polymer composition of claim 1, wherein the polymer composition comprises 0.5 wt% or more of the polydimethylsiloxane, based on the total weight of the polymer composition.
4. 4. The polymer composition of claim 1, wherein the vinyl polymer has a density of 0.926g/cc to 0.940g/cc as measured according to ASTM D792.
5. 5. The polymer composition of claim 1, wherein the polymer composition comprises a fatty acid amide.
6. 6. The polymer composition of claim 1, wherein the polymer composition is free of fatty acid amides.
7. 7. The polymer composition according to claim 6, the polymer composition further comprises: a second polydimethylsiloxane having a weight average molecular weight of 2,000g/mol to 15,000g/mol as measured according to gel permeation chromatography.
8. 8. The polymer composition of any of claims 1-7, wherein the polymer composition exhibits an unaged coefficient of friction of 0.25 or less as measured according to ASTM D1894.
9. 9. The polymer composition of claim 8, wherein the polymer composition exhibits an aged coefficient of friction of 0.25 or less as measured according to ASTM D1894 after aging at 55 ℃ for 336 hours.
10. 10. The polymer composition of any one of claims 1-7, wherein the polymer composition comprises 98 wt% or less of the vinyl polymer based on the total weight of the polymer composition.
11. 11. A coated conductor, the coated conductor comprising: Conductor, and The polymer composition of claim 1 disposed about the conductor.

Description

Low coefficient of friction polymer compositions Technical Field The present disclosure relates generally to polymer compositions, and more particularly to polymer compositions that exhibit low coefficients of friction. Background Introduction to the invention Wires and cables are typically blown and/or pushed into existing conduits and ducts in order to increase fiber densification in the structure. Doing so maximizes the use of new and existing infrastructure. In order to effectively install wires and cables in this manner, the polymer composition of the jacket over the wires and cables needs to have a low coefficient of friction ("COF"). The low coefficient of friction of the polymer composition ensures that the wires and cables do not resist sliding along the surface during installation. In general, to be most effective in an application, the polymer composition of the jacket needs to exhibit an unaged COF of 0.25 or less as measured according to ASTM D1894. Attempts have been made to use various additives to reduce the COF of polymer compositions. One example of such an additive is a slip agent. The slip agent acts as a lubricant on the surface of the polymer composition during processing or in the environment of use. These slip agents generally act by migrating or bloom to the surface of the polymer composition where they provide a COF-reducing coating. Advantageously, the concentration of slip agent at the surface results in less slip agent being required in the polymeric material as a whole. Examples of slip agents include erucamide and low molecular weight siloxanes. Typically, the slip agent within the polymer composition bloom over time, thereby reducing the ability of the jacket to exhibit a low COF. Premature blooming of the slip agent is disadvantageous because long-term storage of the polymer composition after manufacture but prior to wire or cable installation can degrade COF to unusable levels. Thus, in general, the polymer composition must also exhibit a COF of 0.25 (i.e., an "aged COF") as measured according to ASTM D1894 after aging for 336 hours at 55 ℃. Attempts have also been made to use higher molecular polydimethylsiloxanes ("PDMS") to reduce the coefficient of friction of polymer compositions. For example, U.S. patent application No. 2020/0199336A1 ("the '336 publication') discloses a composition using a slip agent blend comprising a first PDMS having a weight average molecular weight (" Mw ") of 30,000g/mol to less than 300,000g/mol, and a second PDMS having a Mw of 300,000g/mol to 2,000,000g/mol, wherein the composition has a COF of 0.25. The' 336 publication shows that the use of only PDMS having a Mw of 300,000g/mol to 2,000,000g/mol (e.g., CS1 and CS 2) in low density polyethylene exhibits high COF of 0.65 and 0.70, respectively. In view of the foregoing, it has surprisingly been found that polymer compositions using a single polydimethylsiloxane having a Mw of 550,000g/mol to 650,000g/mol but capable of achieving an unaged COF of 0.25 or less and an aged COF of 0.25 or less. Disclosure of Invention The present invention provides a polymer composition that uses a single polydimethylsiloxane having a Mw of 550,000g/mol to 650,000g/mol but is capable of achieving an unaged COF of 0.25 or less and an aged COF of 0.25 or less. The present invention is the result of the discovery that the use of PDMS having a Mw of 550,000g/mol to 650,000g/mol in a polymer composition comprising a vinyl polymer having a density of 0.926g/cc to 0.970g/cc is capable of achieving the above characteristics. Without being bound by theory, it is believed that the Mw and viscosity of PDMS results in uniform dispersion within the vinyl polymer during melt compounding. The PDMS was uniformly dispersed to provide an unaged COF of 0.25. Furthermore, the semi-crystalline domains of the vinyl polymer and the Mw of the PDMS act to resist the migration of PDMS over time, thus maintaining an aged COF of 0.25, unlike compositions that rely on additive bloom. The polymer composition is particularly useful for forming sheaths for wires and cables. According to a first feature of the present disclosure, the polymer composition comprises a vinyl polymer having a density of 0.926g/cc to 0.970g/cc as measured according to ASTM D792 and a polydimethylsiloxane having a weight average molecular weight of 550,000g/mol to 650,000g/mol as measured according to gel permeation chromatography. The composition is free of polydimethylsiloxane having a weight average molecular weight of 30,000g/mol to 300,000g/mol as measured by gel permeation chromatography. According to a second feature of the present disclosure, the polymer composition comprises 90 wt% or more of the vinyl polymer based on the total weight of the polymer composition. According to a third feature of the present disclosure, the polymer composition comprises 10wt% or less of polydimethylsiloxane, based on the total weight of the polymer composition. According to a f