Hinge polymer

Patent metadata

Field	Value
Publication number	US-9353250-B2
Application number	US-201414205628-A
Country	US
Kind code	B2
Filing date	Mar 12, 2014
Priority date	Mar 14, 2013
Publication date	May 31, 2016
Grant date	May 31, 2016

Abstract

A polymer suitable for use in a thin film hinge (living hinge) comprising from about 0.1 to about 5 weight % of a C 4-8 comonomer and the balance ethylene, said composition having a density as determined according to ASTM D 792 from about 0.945 to about 0.965 g/cm 3 ; a melt index as determined according to ASTM D1238 (2.16 kg/190° C.) from about 10 to about 20 g/10 min; a weight average molecular weight (Mw) from about 45,000 to about 55,000 g/mol; a polydispersity from about 2.5 to about 3.1 and when molded into a strip having a length of about 13 cm and gross thickness from about 50 to about 70 mil (about 1 to about 2 mm) and completely bent over end to end four times to create a thinned region or crease having a thickness from about 15 to about 30 mil (about 0.3 to about 0.7 mm) tested by bending and releasing the deformed thinned region of the strip through a radius of curvature from about 180 to about 190° about a rounded plate goes through not less than 500 cycles without breaking.

First claim

What is claimed is:

1. A polyethylene composition consisting of:
i) from 60 to 80 weight % of a polyethylene consisting of: from 0.1 to 0.5 weight of 1-butene and the balance ethylene, said composition having a density as determined according to ASTM D 792 from 0.948 to 0.952 g/cm 3 ; a melt index as determined according to ASTM D1238 (2.16 kg 190° C.) from 16 to 18 g/10 min; a weight average molecular weight (Mw) from 48,000 to 52,000 g/mol; a polydispersity from 2.7 to 3.0 and;
ii) from 40 to 20 wt. % of a polyethylene homopolymer having a density from 0.960 g/cm 3 to 0.965 g/cm 3 ; a melt index as determined according to ASTM D1238 (2.16 kg 190° C.) from 12 to 14 g/10 min, a weight average molecular weight (Mw) from 55,000 to 63,000 and a polydispersity from 3.0 to 3.3;
wherein said polyethylene composition has a density according to ASTM 792 from 0.950 to 0.960 g/cm 3 , a tensile strength at yield from 24 to 28 MPa, and when molded into a strip having a length of 13 cm and gross thickness from 50 to 70 mil (1 to 2 mm) and completely bent over end to end four times to create a creased strip having a thinned region having a thickness from 15 to 30 mil (0.3 to 0.3 mm); said creased strip is tested in a bending and releasing cycle until breaking; wherein said thinned region is bent and released through a radius of curvature of 180° to 190° about a rounded plate until said creased strap breaks; wherein said creased strip goes through from about 650 to 2510 cycles prior to breaking.

2. The polyethylene composition according to claim 1 , wherein said creased strip goes through from about 750 to 2510 bending and releasing cycles prior to breaking.

3. The polyethylene composition according to claim 1 , wherein the polyethylene composition has a lower comonomer content at higher molecular weight.

4. The polyethylene composition according to claim 1 , wherein component i) and component ii) are solution polymerized.

5. The polyethylene composition according to claim 1 , wherein said creased strip through from about 900 to 2510 bending and releasing cycles prior to breaking.

Assignees

• Nova Chem Int Sa

Inventors

• Rycroft Jason Michael
• Arnould Gilbert Alexander
• Botros Matthew Zaki
• Rejman Mark

Classifications

• G01N2203/0464

  with provisions for testing more than one specimen at the time · CPC title

• G01N2203/0023

  Bending · CPC title

• G01N3/36

  generated by pneumatic or hydraulic means · CPC title

• C08L2205/02

  containing two or more polymers of the same C08L -group · CPC title

• G01N3/32

  by applying repeated or pulsating forces · CPC title