MULTILAYER FILMS AND METHODS THEREOF

• US 20190322086A1
• Filed: 08/08/2017
• Published: 10/24/2019
• Est. Priority Date: 08/24/2016
• Status: Active Grant

• Current Assignee: Dow Global Technologies LLC (Dow, Inc.)
• Original Assignee: Dow Global Technologies LLC (Dow, Inc.)
• Inventors: Lee, Jong Young, Munj, Hrishikesh R.
• Granted Patent: US 11,407,206 B2
• Time in Patent Office: Days
• CPC Class Codes: B29C 48/0018 combined with shaping by orienting, stretching or shrinking, e.g. film blowing B29C48/0017 takes precedence
• CPC Class Codes: B29C 48/16 Articles comprising two or more components, e.g. co-extruded layers
• CPC Class Codes: B29C 48/912 of tubular films
• CPC Class Codes: B29D 23/24 Endless tubes, e.g. inner tubes for pneumatic tyres producing ring shaped inner tubes with ends B29D22/026; inflatable inner tubes for tyres B60C5/00
• CPC Class Codes: B29K 2023/0633 LDPE, i.e. low density polyethylene
• CPC Class Codes: B29K 2023/08 Copolymers of ethylene B29K2023/16 takes precedence
• CPC Class Codes: B32B 2270/00 Resin or rubber layer containing a blend of at least two different polymers
• CPC Class Codes: B32B 2274/00 Thermoplastic elastomer material thermoplastic elastomer fibres B32B2262/0215, thermoplastic elastomer particles B32B2264/0221, thermoplastic elastomer foam B32B2266/0292
• CPC Class Codes: B32B 2307/30 having particular thermal properties
• CPC Class Codes: B32B 2307/72 Density
• CPC Class Codes: B32B 2307/744 Non-slip, anti-slip
• CPC Class Codes: B32B 2307/748 Releasability
• CPC Class Codes: B32B 2405/00 Adhesive articles, e.g. adhesive tapes labels B32B2519/00
• CPC Class Codes: B32B 2439/02 Open containers
• CPC Class Codes: B32B 2439/70 Food packaging
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/32 comprising polyolefins comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30
• CPC Class Codes: B32B 27/327 comprising polyolefins obtained by a metallocene or single-site catalyst
• CPC Class Codes: B32B 7/06 permitting easy separation

Abstract

Embodiments disclosed herein include multilayer blown films having a cling layer and a release layer, wherein the cling layer comprises (i) an ethylene/alpha-olefin elastomer, and (ii) a polyethylene polymer selected from ultra-low density polyethylene, a very low density polyethylene, or combinations thereof, and the release layer comprises an ethylene/alpha-olefm resin.

Claims

1. A multilayer blown film comprising a cling layer and a release layer, wherein:

the cling layer comprises;

(i) an ethylene/alpha-olefin elastomer having a density in the range of 0.855 to 0.890 grams/cm³ and a melt index, I₂, in the range of 0.1 to 30 grams/10 minutes; and

(ii) a polyethylene polymer selected from ultra-low density polyethylene, a very low density polyethylene, or combinations thereof, wherein the polyethylene polymer has a density in the range 0.885 to 0.915 grams/cm³, a melt index, I₂, in the range of 0.1 to 30 grams/10 minutes, and a purge fraction greater than 20 percent as determined by the Crystallization Elution Fractionation (CEF) test method; and

the release layer comprises an ethylene/alpha-olefin resin that is characterized by the following properties;

(a) a melt index, 12, of from 0.1 to 30.0 g/10 min;

(b) a density of from 0.910 to 0.930 g/cc; and

(c) a purge fraction of less than 2% as determined by the Crystallization Elution Fractionation (CEF) test method.

2. The film of claim 1, wherein the release layer comprises from 20 wt. % to 90 wt. % of the ethylene/alpha-olefin resin.

3. The film of claim 1, wherein the release layer further comprises a low density polyethylene.

4. The film of claim 1, wherein the ethylene/alpha-olefin resin of the release layer has a purge fraction of less than 1%.

5. The film of claim 1, wherein the ethylene/alpha-olefin resin of the release layer has a melt index of from 0.1 to 2.0 g/10 min.

6. The film of claim 1, wherein the ethylene/alpha-olefin resin of the release layer is further characterized by a composition distribution breadth index (CDBI) of greater than 55.

7. The film of claim 1, wherein the cling layer comprises from 20 wt. % to 90 wt. % of the ethylene/alpha-olefin elastomer.

8. The film of claim 1, wherein the film further comprises a core layer positioned between the cling layer and the release layer.

9. The film of claim 1, wherein the cling layer has a thickness that is from 5-30 percent of the overall thickness of the film.

10. The film of claim 1, wherein the release layer has a thickness that is from 5-30 percent of the overall thickness of the film.

11. A method of making a multilayer blown film, the method comprising:

providing a cling layer composition comprising (i) an ethylene/alpha-olefin elastomer having a density in the range of 0.855 to 0.890 grams/cm³ and a melt index, I₂, in the range of 0.1 to 30 grams/10 minutes; and

(ii) a polyethylene polymer selected from ultra-low density polyethylene, a very low density polyethylene, or combinations thereof, wherein the polyethylene polymer has a density in the range 0.885 to 0.915 grams/cm³, a melt index, I₂, in the range of 0.1 to 30 grams/10 minutes, and a purge fraction greater than 20 percent as determined by the Crystallization Elution Fractionation (CEF) test method;

providing a release layer composition comprising an ethylene/alpha-olefin resin that is characterized by the following properties;

(a) a melt index, I₂, of from 0.1 to 30.0 g/10 min;

(b) a density of from 0.910 to 0.930 g/cc; and

(c) a purge fraction of less than 2% as determined by the Crystallization Elution Fractionation (CEF) test method;

coextruding the cling layer composition with the release layer composition in an extruder to form a tube having a cling layer and a release layer; and

cooling the tube to form a multilayer blown stretch film.