Stretch film cling enhancement by addition of elastomers

• US 5,085,927 A
• Filed: 04/10/1990
• Issued: 02/04/1992
• Est. Priority Date: 04/10/1990
• Status: Expired due to Fees

• Current Assignee: Paragon Films Incorporated
• Original Assignee: Paragon Films Incorporated
• Inventors: Dohrer, Gregory L.
• Primary Examiner(s): SLUBY, PATRICIA
• Application Number:
  US07/507,311
• Time in Patent Office: 665 Days
• Field of Search: 428/220, 428/516, 428/520, 428/517, 428/349
• US Class Current: 428/220
• CPC Class Codes: B32B 2250/40 Symmetrical or sandwich layers, e.g. ABA, ABCBA, ABCCBA
• CPC Class Codes: B32B 2307/54 Yield strength; Tensile strength
• CPC Class Codes: B32B 2323/043 HDPE, i.e. high density polyethylene
• CPC Class Codes: B32B 2323/046 LDPE, i.e. low density polyethylene
• CPC Class Codes: B32B 2323/10 Polypropylene
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/302 comprising aromatic vinyl (co)polymers, e.g. styrenic (co)polymers
• CPC Class Codes: B32B 27/32 comprising polyolefins comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30
• CPC Class Codes: B32B 7/12 using interposed adhesives or interposed materials with bonding properties
• CPC Class Codes: Y10T 428/2826 Synthetic resin or polymer
• CPC Class Codes: Y10T 428/31913 Monoolefin polymer
• CPC Class Codes: Y10T 428/31917 Next to polyene polymer
• CPC Class Codes: Y10T 428/31928 Ester, halide or nitrile of addition polymer

Abstract

An enhancement of the cling property of stretch wrap is obtained by adding a linear styrenic elastomer having a melt index between about 5 and about 10 g/10 mins to the cling layer of a film in addition to the usually added tackifiers. The invention enhanced cling layer films can be produced as A/B, A/B/A OR A/B/C films.

Claims

1. A stretch wrap film comprising layers A and B wherein layer A has a cling force to another layer A of at least about 150g, measured according to ASTM D4649, and wherein layer A comprises at least one linear styrenic elastomer and a tackifier, said linear styrenic elastomer having a melt index as measured by ASTM 1238 Condition G of from about 5 to about 10g.10 mins and containing less than about 30 wt.% styrene;

and said B layer is comprised of a polyolefin.

2. The stretch wrap film of claim 1 wherein the at least one elastomer comprises styrene butadiene, styrene-isoprene, styrene-butadiene-styrene, styrene-ethylene-butadiene-styrene or styrene-isoprene-styrene.

3. The stretch wrap film of claim 1 wherein layer A comprises from about 5 to about 30 wt.% of the elastomer.

4. The stretch wrap film of claim 1, further comprising a C layer to from an A/B/C film structure wherein the coefficient of friction of the C surface of said film to another C surface is less than 2.0.

5. The stretch wrap film of claim 4, wherein said coefficient of friction is less than 1.0.

6. The stretch wrap film of claim 1, wherein the B layer has a tensile strength between about 4,000 to about 12,000 psi.

7. The stretch wrap film of claim 4, wherein the A:

B;

C weight ratio is between from about 5;

90;

5 to about 30;

40;

30.

8. The stretch wrap film of claim 7, wherein the A:

B;

C ratio is approximately 10;

80;

10.

9. The stretch wrap film of claim 1, wherein said B layer is fabricated from a polyolefin selected from the group consisting of polyethylene, polypropylene and a copolymer of ethylene, propylene and a C₄ -C₁₂ mono-olefin.

10. The stretch wrap film of claim 9, wherein said polyolefin is linear low density polyethylene.

11. The stretch wrap film of claim 4, wherein said C layer comprises polypropylene and high density polyethylene.

12. The stretch wrap film of claim 4, wherein the C layer further comprises an anti-block agent in an amount sufficient to produce a cling force of approximately zero.

13. The stretch wrap film of claim 11, wherein said layer C comprises approximately 30 weight percent high density polyethylene.

14. The stretch wrap film of claim 1 further comprising an additional layer A to form an A/B/A film structure and wherein at least one of the layers A comprises at least one elastomers.

15. The stretch wrap film of claim 14 wherein the at least one elastomer comprises styrene butadiene, styrene-isoprene, styrene-butadiene-styrene, styrene-ethylene-butadiene-styrene or styrene-isoprene-styrene.

16. The stretch wrap film of claim 14 wherein the elastomer comprises from about 5 to about 30 wt.% of layer A.

17. The stretch wrap film of claim 14 wherein the cling force of layer A to a like surface A is 150 to 600 g, as measured according to ASTM D4649.

18. The stretch wrap film of claim 14 wherein the B layer has a tensile strength from about 40,000 psi to about 12,000 psi.