Multilayer polyolefin greenhouse films with high transparency

Patent metadata

Field	Value
Publication number	US-11319419-B2
Application number	US-201716612003-A
Country	US
Kind code	B2
Filing date	May 11, 2017
Priority date	May 11, 2017
Publication date	May 3, 2022
Grant date	May 3, 2022

Abstract

A multilayer film (10) having excellent mechanical strength and transparency comprise a core layer (12), at least two skin layers, and at least two sub-skin layers disposed between the core layer (12) and the two skin layers. The core layer (12) comprises at least 60 wt. % linear low density polyethylene (LLDPE). The sub-skin layers comprise at least 60 wt. % low density polyethylene (LDPE). The skin layers comprise at least 80 wt. % of LLDPE wherein the LLDPE comprises C6 LLDPE, C8 LLDPE, or combinations thereof, and each skin layer has a thickness of less than 25% of the overall thickness of the multilayer film (10). The multilayer film (10) comprises at least 0.1 wt. % ultraviolet stabilizer.

First claim

The invention claimed is:

1. A multilayer film comprising at least 5 layers, the at least 5 layers comprising a core layer, at least two skin layers, and at least two sub-skin layers disposed between the core layer and the two skin layers, wherein:
the core layer comprises at least 60 wt. % linear low density polyethylene (LLDPE) having a density of 0.900 to 0.945 g/cc and a melt index (I 2 ) from 0.5 to 2.0 g/10 min when measured according to ASTM D1238 at 190° C. and 2.16 kg load;
the sub-skin layers comprise at least 60 wt. % low density polyethylene (LDPE) having a density of 0.912 to 0.935 g/cc, a melt index, I 2 , from 0.15 to 2.0 g/10 min;
the skin layers comprise at least 80 wt. % LLDPE having a density of from 0.900 to 0.945 g/cc and a melt index, I 2 , from 0.5 to 2.0 g/10 min, wherein the LLDPE of the skin layers comprise C6 LLDPE, C8 LLDPE, or combinations thereof, wherein each skin layer has a thickness of less than 25% of the overall thickness of the multilayer film;
the multilayer film comprises at least 0.1 wt. % ultraviolet (UV) stabilizer; and
the multilayer film exhibits a clarity greater than 95% at an overall thickness of 80 μm.

2. The multilayer film of claim 1 wherein the core layer comprises at least 80 wt. % LLDPE.

3. The multilayer film of claim 1 , the core layer, the sub-skin layers, and the skin layers are substantially free of acrylate polymers.

4. The multilayer film of claim 1 wherein the multilayer film is substantially free of propylene-based polymer.

5. The multilayer film of claim 1 wherein the LLDPE of the skin layers or the core layers comprise a density of 0.915 to 0.925 g/cc.

6. The multilayer film of claim 1 wherein the sub-skin layers comprise at least 80 wt. % LDPE, the LDPE having a melt index, I 2 , from 0.15 to 1.0 g/10 min.

7. The multilayer film of claim 1 wherein the multilayer film comprises from 15 to 50 wt. % LDPE.

8. The multilayer film of claim 1 wherein the multilayer film comprises from 50 to 85 wt. % LLDPE.

9. The multilayer film of claim 1 wherein the overall thickness is from 50 to 150 μm.

10. The multilayer film of claim 1 wherein the multilayer film exhibits a haze less than 10% at an overall thickness of 80 μm as measured according to ASTM D1003.

11. The multilayer film of claim 1 wherein the multilayer film comprises ethylene vinyl acrylate in any layer, an additional layer comprising ethylene vinyl acrylate, or both.

12. The multilayer film of claim 1 further comprising high density polyethylene (HDPE) having a density of 0.945 to 0.965 g/cc and a melt index (I 2 ) from 0.5 to 5.0 g/10 min.

13. The multilayer film of claim 1 further comprising one or more additives selected from the group consisting of antioxidants, UV absorbers, infrared (IR) absorber, anti-fogging agents, and anti-dripping agents.

Assignees

• Dow Global Technologies Llc

Inventors

• Chen Yong
• Yun Xiaobing
• Du Libo

Classifications

• B32B2250/05

  5 or more layers · CPC title

• B32B2250/40

  Symmetrical or sandwich layers, e.g. ABA, ABCBA, ABCCBA · CPC title

• B32B2270/00

  Resin or rubber layer containing a blend of at least two different polymers · CPC title

• B32B2307/732

  Dimensional properties · CPC title

• B32B2250/246

  All polymers belonging to those covered by groups B32B27/32 and B32B27/30 · CPC title