Multilayer separator with superior permeability

Patent metadata

Field	Value
Publication number	US-9623640-B2
Application number	US-201414580885-A
Country	US
Kind code	B2
Filing date	Dec 23, 2014
Priority date	Dec 27, 2013
Publication date	Apr 18, 2017
Grant date	Apr 18, 2017

Abstract

Provided are a multilayer separator capable of improving interlayer peel strength and exhibiting excellent permeability due to a high degree of alignment, and a method of manufacturing the same. The method of manufacturing a multilayer separator includes: manufacturing a precursor film by co-extruding and molding a polypropylene based resin melt having a melt index (2.16 kg, 230° C.) of 0.3 to 5 g/10 min and a polyethylene based resin melt having a melt index (2.16 kg, 190° C.) of 0.1 to 1.5 g/10 min so as to be alternately laminated; and heat-treating and stretching the manufactured film, wherein a melt index ratio (A/B) of the polypropylene based resin melt (A) and polyethylene based resin melt (B) is 2 to 10.

First claim

What is claimed is:

1. A method of manufacturing a multilayer separator, the method comprising:
manufacturing a precursor film by co-extruding and molding a polypropylene based resin melt having a melt index (2.16 kg, 230° C.) of 0.3 to 5 g/10 min and a polyethylene based resin melt having a melt index (2.16 kg, 190° C.) of 0.1 to 1.5 g/10 min so as to be alternately laminated; and
heat-treating and stretching the manufactured film,
wherein a melt index ratio (A/B) of the polypropylene based resin melt (A) and polyethylene based resin melt (B) is 2 to 10, and
the manufacturing of the precursor film is performed in a range in which the draw down speed of the resin melt is 160 to 3,000 l/sec., wherein the draw down speed, DDS, is defined by the following equation:
DDS(l/sec.)= D/t× 1000 ×V f /(2 ×d )/60=DDR× V f /(120× d ),

where,
D is the die gap in mm;
t is the thickness of film in μm;
V f is the final winding speed of the film in m/min;
d is the distance from an exit of a die to a frost line of the film in m; and
DDR is the draw down ratio.

2. The method of claim 1 , wherein in the manufacturing of the precursor film, the molding is performed in a range in which a draw down ratio is 100 to 450, wherein the draw down ratio, DDR, is defined by the following equation:
DDR= D/t× 1000,
where,
D is the die gap in mm; and
t is the thickness of film in μm.

3. The method of claim 1 , wherein in the manufacturing of the precursor film, the molding is performed by a casting method.

Assignees

• Sk Innovation Co Ltd

Inventors

• Jeon Min Ho
• Jo Byoung Cheon
• Cheong Sang Bae
• Park Sang Hyun
• Kan Tae Gyu

Classifications

• Y10T428/31913

  Monoolefin polymer · CPC title

• B32B27/32 Primary

  comprising polyolefins {(comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30)} · CPC title

• B29D7/01

  Films or sheets · CPC title

• B32B27/08 Primary

  of synthetic resin · CPC title

• B29D99/005

  Producing membranes · CPC title