Breathable packaging film having enhanced thermoformability

a technology of packaging film and thermoformability, which is applied in the field of food packaging film with thermoformability coextruding, to achieve the effect of improving thermoformability and exceptional optical properties

Inactive Publication Date: 2006-05-18
BEMIS COMPANY INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0007] It is another object of the present invention to provide a coextruded packaging film having improved thermoformability. The present invention provides such thermoformable multilayer films which are particularly well suited for forming a package in which the film is molded into a cavity in which a product may be placed. Such multilayer films may be characterized as having a linear free shrink at 80° C. of 0-5% in both the machine and transverse directions as measure in accordance with ASTM D-2732-96 test method.
[0008] It is yet another object of the present invention to provide a thermoformable coextruded packaging film which exhibits exceptional optical properties. The present invention provides multilayer films having a gloss value at 45° of at least 60% as measure in accordance with ASTM D-2457-03 test method and a haze value of less than 20% as measured in accordance with ASTM D-1003-00 test method.

Problems solved by technology

Not withstanding the fairly high state of development in the art, packaging manufacturers are continually striving to improve the functionality of their packaging materials.

Method used

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  • Breathable packaging film having enhanced thermoformability
  • Breathable packaging film having enhanced thermoformability
  • Breathable packaging film having enhanced thermoformability

Examples

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example 1

[0052] Example 1 is one embodiment of the present invention of a film having seven layers (see film 20 in FIG. 2). The first polymeric layer (21) comprised a mixture of polyester, anti-block additive and slip additive. The polyester comprised polyethylene terephthalate copolymer having a density of 1.4 g / cm3, a melting point of 240° C., a tensile strength at break (machine direction / transverse direction) of 8.4 / 5.6 kpsi, and is available under the trademark Voridian™ Polymer 9921 from Eastman Chemical Company, Kingsport, Tenn., U.S.A. In Example 1, the second layer (22) was a tie layer comprising ethylene / methyl acrylate copolymer (E / MA) and modified linear low-density polyethylene (m-LLDPE). The ethylene / methyl acrylate copolymer has a density of 0.948 g / cm3, a melting point of 49° C., a melt index of 2.0 g / 10 min., and is available from Eastman Chemical Company, Kingsport, Tenn., U.S.A. The modified linear low-density polyethylene was an anhydride linear low-density polyethylene h...

example 2

[0054] In Example 2, the film is another example of a seven-layer embodiment of the present invention. All the film layers are identical in structure and relative layer thickness as that used in Example 1, except that the overall film thickness was about 8 mil.

[0055] Example 2 had an oxygen transmission rate at 73° C. and 0% R.H. of 20 cm3 / 100 in2 / 24 h. (310 cm3 / m2 / 24 h.) as measured in accordance with ASTM D-3985-02 test method.

[0056] Unless otherwise noted, the physical properties and performance characteristics reported herein were measured by test procedures similar to the following methods. The following ASTM test procedures are each incorporated herein by reference in their entireties.

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Abstract

The present invention describes thermoformable coextruded film suitable for use in packaging applications having at least a first polymeric layer serving as an outermost exterior-film layer and comprising a cycloaliphatic polyester, an aromatic polyester or blends thereof; a second polymeric layer serving as a thermoforming-assist layer and comprising a polyolefin; and a third polymeric layer serving as an innermost exterior-film layer and comprising a heat-sealing polyolefinic material. The films of the present invention are oxygen-permeable in that they exhibit an oxygen transmission rate of between 2-1000 cm3/100 in2/24 h.atm.

Description

FIELD OF THE INVENTION [0001] The present invention generally relates to food packaging films, and particularly, to thermoformable coextruded packaging films having special utility in the packaging of fresh poultry, meats, fruits and vegetables. BACKGROUND OF THE INVENTION [0002] Thermoforming and other similar techniques are well known in the art for packaging products. Suitable thermoforming methods, for example, include a vacuum forming or plug-assist vacuum forming method. In the vacuum forming method, a first film is heated, for example, by a contact heater and a vacuum is applied beneath the film causing the web to be pushed by atmospheric pressure down into a preformed mold. In a plug-assist vacuum forming method, after the first or forming film has been heated and sealed across a mold cavity, a plug shape similar to the mold shape impinges on the forming film and, upon the application of vacuum, the forming film transfers to the mold surface. After the forming film is in pla...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B32B27/08B32B27/36B32B27/30B32B27/32
CPCB32B27/08Y10T428/2826B32B27/32B32B27/36B32B2250/24B32B2307/406B32B2307/724B32B2307/738B32B2439/70Y10T428/26Y10T428/28Y10T428/2813Y10T428/27Y10T428/2878Y10T428/2817Y10T428/269B32B27/308Y10T428/31786Y10T428/31797Y10T428/31855Y10T428/31909Y10T428/31913Y10T428/31928Y10T428/31935Y10T428/31938
Inventor LISCHEFSKI, ANDREW J.NELSON, KEVIN P.
Owner BEMIS COMPANY INC
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