Antifog polyester lidding film for cpet trays

Patent metadata

Field	Value
Publication number	US-2018281363-A1
Application number	US-201715476413-A
Country	US
Kind code	A1
Filing date	Mar 31, 2017
Priority date	Mar 31, 2017
Publication date	Oct 4, 2018
Grant date	—

Abstract

The present disclosure is directed to peelable, heat-sealable lidding films for containers of diverse polymer compositions storing various products such as foodstuffs and pharmaceuticals. The lidding films disclosed herein can be heat-sealed to crystalline polyester trays (CPET), easily peeled, and contain improved antifogging performance by incorporating a non-migratory antifogging additive into the heat sealable layer of the film without deteriorating seal strengths.

First claim

1 . A lidding film comprising:
a biaxially oriented polyester-based base film; and an extrusion-coated heat seal structure on a side of the base film, wherein the heat seal structure comprises a skin layer comprising 0.2-5.5 wt % non-migratory antifog active ingredient and 70-99 wt % ethylene vinyl acetate (EVA).

2 . The lidding film of claim 1 , wherein the non-migratory antifog active ingredient comprises a non-ionic surfactant and a salt of organic sulfonic acid.

3 . The lidding film of claim 2 , wherein the weight ratio of the non-ionic surfactant to the salt of organic sulfonic acid is 20/80-99/1.

4 . The lidding film of claim 1 , wherein the skin layer comprises a polyethylene carrier resin for the non-migratory antifog active ingredient.

5 . The lidding film of claim 4 , wherein the non-migratory antifog active ingredient comprises 10-25 wt % of the combination of non-migratory antifog active ingredient and polyethylene carrier resin in the skin layer.

6 . The lidding film of claim 1 , wherein the polyester-based base film comprises a crystalline polyester base layer and an amorphous polyester skin layer.

7 . The lidding film of claim 6 , wherein the extrusion-coated heat seal structure is on a side of the amorphous polyester skin layer opposite the crystalline polyester base layer.

8 . The lidding film of claim 6 , wherein the crystalline polyester base layer comprises a polyester resin with an intrinsic viscosity of 0.5-0.9 dl/g.

9 . The lidding film of claim 6 , wherein the crystalline polyester base layer comprises polyethylene terephthalate.

10 . The lidding film of claim 6 , wherein the amorphous polyester skin layer comprises at least one of isophthalate modified copolyesters, sebacic acid modified copolyesters, diethyleneglycol modified copolyesters, triethyleneglycol modified copolyesters, or cyclohexanedimethanol modified copolyesters.

11 . The lidding film of claim 7 , further comprising a primer layer between the amorphous polyester skin layer and the heat seal structure.

12 . The lidding film of claim 1 , further comprising a primer layer between the polyester-based base film and the extrusion-coated heat seal structure.

13 . The lidding film of claim 1 , wherein the polyester-based base film comprises 0.1-0.4 wt % antiblock or slip additives.

14 . The lidding film of claim 1 , wherein the heat seal structure comprises a core layer comprising EVA on a side of the skin layer.

15 . The lidding film of claim 14 , wherein the heat seal structure comprises a tie layer comprising low density polyethylene (LDPE) on a side of the core layer opposite the skin layer.

16 . The lidding film of claim 15 , further comprising a primer layer between the tie layer and the base film.

17 . The lidding film of claim 1 , wherein the lidding film has an antifog ranking of at least 6.

18 . The lidding film of claim 1 , wherein the lidding film has a seal strength to crystalline polyester trays of 500-2500 gf/in.

19 . A lidding film comprising:
a biaxially oriented polyester-based base film comprising a crystalline polyester base layer and an amorphous polyester skin layer; and an extrusion-coated heat seal structure on a side of the base film, wherein the heat seal structure comprises:
a tie layer comprising low density polyethylene (LDPE) on a side of the amorphous polyester skin layer opposite the crystalline polyester base layer;
a core layer comprising EVA on a side of the tie layer opposite the amorphous polyester skin layer; and
a skin layer comprising 0.2-5.5 wt % non-migratory antifog active ingredient and 70-99 wt % ethylene vinyl acetate (EVA) on a side of the core layer opposite the tie layer.

20 . The lidding film of claim 19 , further comprising a primer layer between the amorphous polyester skin layer and the tie layer.

21 . A method of forming a lidding film comprising:
biaxially orienting a polyester-based base film; and extrusion coating a heat seal structure comprising a skin layer comprising 0.2-5.5 wt % non-migratory antifog active ingredient and 70-99 wt % ethylene vinyl acetate (EVA) on a side of the polyester-based base film.

22 . The method of claim 21 , wherein the non-migratory antifog active ingredient comprises a non-ionic surfactant and a salt of organic sulfonic acid.

23 . The method of claim 22 , wherein the weight ratio of the non-ionic surfactant to the salt of organic sulfonic acid is 20/80-99/1.

24 . The method of claim 21 , wherein the skin layer comprises a polyethylene carrier resin for the non-migratory antifog active ingredient.

25 . The method of claim 24 , wherein the non-migratory antifog active ingredient comprises 10-25 wt % of the combination of non-migratory antifog active ingredient and polyethylene carrier resin in the skin layer.

26 . The method of claim 21 , further comprising co-extruding a crystalline polyester base layer and an amorphous polyester skin layer to form the polyester-based base film.

27 . The method of claim 26 , wherein the heat seal structure is extrusion coated on a side of the amorphous polyester skin layer opposite the crystalline polyester base layer.

28 . The method of claim 21 , further comprising solution coating a primer layer on a side of the polyester-based base film, wherein the extrusion-coated skin layer is on a side of the primer layer opposite the polyester-based base film.

29 . The method of claim 28 , wherein the solution coating comprises gravure roll coating.

30 . The method of claim 21 , further comprising corona treating the skin layer.

31 . The method of claim 21 , wherein the lidding film has an antifog ranking of at least 6.

32 . The method of claim 21 , wherein the lidding film has a seal strength to crystalline polyester trays of 500-2500 gf/in.

33 . A method of forming a lidding film comprising:
co-extruding a crystalline polyester base layer and an amorphous polyester skin layer to form a polyester-based base film; biaxially orienting the polyester-based base film; solution coating a primer layer comprising polyethylenimine on a side of the amorphous polyester skin layer opposite the crystalline polyester base layer; extrusion coating a tie layer comprising LDPE on a side of the primer layer opposite the amorphous polyester skin layer; extrusion coating a core layer comprising EVA on a side of the tie layer opposite the primer layer; and extrusion coating a skin layer comprising 0.2-5.5 wt % non-migratory antifog active ingredient and 70-99 wt % ethylene vinyl acetate (EVA) on a side of core layer opposite the tie layer.

Assignees

• Toray Plastics America Inc

Inventors

• Shoolbraid Kari
• Sakai Takafumi

Classifications

• B32B2250/24

  All layers being polymeric · CPC title

• B32B7/12

  using interposed adhesives or interposed materials with bonding properties · CPC title

• B32B27/306

  comprising vinyl acetate or vinyl alcohol (co)polymers · CPC title

• B32B2307/518

  bi-axially · CPC title

• B32B2307/748

  Releasability · CPC title