Antifog polyester lidding film for CPET trays

Patent metadata

Field	Value
Publication number	US-11267233-B2
Application number	US-202016847889-A
Country	US
Kind code	B2
Filing date	Apr 14, 2020
Priority date	Mar 31, 2017
Publication date	Mar 8, 2022
Grant date	Mar 8, 2022

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

The invention claimed is:

1. 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.

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

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

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

6. The method of claim 1 , wherein the solution coating comprises gravure roll coating.

7. The method of claim 1 , further comprising corona treating the skin layer.

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

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

Assignees

• Toray Plastics America Inc

Inventors

• Shoolbraid Kari
• Sakai Takafumi

Classifications

• B32B2331/04

  Polymers of vinyl acetate, e.g. PVA · CPC title

• B32B2307/702

  Amorphous · CPC title

• B32B2307/704

  Crystalline · CPC title

• B32B2307/744

  Non-slip, anti-slip · CPC title

• B32B2307/748

  Releasability · CPC title