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BR-112022001626-B1 - Stain-resistant packaging film for retort applications.

BR112022001626B1BR 112022001626 B1BR112022001626 B1BR 112022001626B1BR-112022001626-B1

Abstract

STAIN-RESISTANT PACKAGING FILM FOR RETORTING APPLICATIONS. To reduce the amount of staining that occurs during retort processing in food packaging, a packaging film is used that includes a white multilayer film, wherein the white multilayer film has a sealing region on the exposed surface of the packaging film, a white region containing white pigment, and a blocking region located between the white region and the sealing region, wherein the combined thickness of the sealing region and the blocking region is at least 70% of the thickness of the white multilayer film.

Inventors

  • JAMES R. LAMB
  • CAROL W. UMPHLETT
  • CURTIS R. BARR

Assignees

  • Amcor Flexibles North America, Inc

Dates

Publication Date
20260310
Application Date
20200804
Priority Date
20190805

Claims (10)

  1. 1. Stain-resistant packaging film for retort processing (20) characterized in that it comprises a white multilayer film (300), wherein the white multilayer film (300) comprises: a sealing region (330), wherein the sealing region (330) is located on an exposed surface (24, 324) of the packaging film, a white region (310) comprising a white pigment in an amount of 3.5% to 35% by weight and a propylene-based polymer, and a blocking region (320), wherein the blocking region (320) is located between the sealing region (330) and the white region (310), wherein the sealing region (330) and the blocking region (320) each comprise a propylene-based polymer and are each essentially free of the white pigment, the blocking region (320) containing a mixture including a polypropylene homopolymer, and a The combined thickness (402) of the sealing region (330) and the blocking region (320) is at least 70% of a thickness (400) of the white multilayer film (300).
  2. 2. Stain-resistant packaging film (20), according to claim 1, characterized in that the blocking region (320) comprises a blend of a propylene-ethylene copolymer and a polypropylene homopolymer in an amount of at least 10% by weight.
  3. 3. Stain-resistant packaging film (20), according to claim 1, characterized in that the blocking region (320) comprises a rubber-modified polypropylene copolymer in an amount between 0% and 10% by weight.
  4. 4. Stain-resistant packaging film (20), according to claim 1, characterized in that the sealing region (330) comprises a blend of a rubber-modified polypropylene copolymer and a polypropylene homopolymer of up to 10%.
  5. 5. Stain-resistant packaging film according to claim 1, characterized in that the thickness (400) of the white multilayer film (300) is between 50 microns and 500 microns.
  6. 6. Stain-resistant packaging film (20), according to claim 1, characterized in that it further comprises printed symbols.
  7. 7. Stain-resistant packaging film (20), according to claim 1, characterized in that the white multilayer film (300) is free of EVOH or polyamide.
  8. 8. Stain-resistant packaging film (20), according to claim 1, characterized in that it further comprises an outer exploration layer (100) and a barrier layer (200), wherein the barrier layer (200) is located between the outer exploration layer (100) and the white multilayer film (300).
  9. 9. Stain-resistant packaging film (20), according to claim 8, characterized in that the barrier layer (200) is an inorganic oxide coating.
  10. 10. Stain-resistant packaging film (20), according to claim 8, characterized in that both the outer exploration layer (100) and the barrier layer (200) are transparent, and in that the white region (310) of the white multilayer film (300) can be viewed through the outer exploration layer (100).

Description

FIELD OF TECHNIQUE [0001] This disclosure relates to film structures, in particular to white film structures to be used for food packaging in retort applications. The laminates described in this document exhibit reduced food staining. BACKGROUND [0002] Retorting operations are used for the thermal processing of food and the sterilization of primary packaging components. Food packaged in a retortable container is transferred to an autoclave unit where it is subjected to retorting conditions, including humid or wet environments, temperatures that generally exceed the boiling point of water, and high pressures, for a specific period of time. Retortable containers are therefore designed to withstand retorting conditions. [0003] Flexible, multi-layered high-barrier films are commonly used for packaging food items that are sterilized by retorting. For example, a flexible film can be heat-sealed into an upright pouch, filled with a food product, and hermetically sealed before retort processing. Another common packaging format for retort processing is a polymer or metal tray to which a flexible lid is heat-sealed to hermetically enclose the food product. A wide variety of food products can be enclosed within retort packaging, including soups, vegetables, or pasta with sauce. [0004] Often, packaging film is printed with graphics suitable for the retail sale of the food product. As a backdrop for the graphics, a portion of the film is usually pigmented with white. This is typically done by including a layer of solid white ink along with the graphics or by pigmenting one of the polymeric layers of the film that is behind the printed graphics. [0005] When using a pigmented white film, the film may become stained by the food product during the retort process. The staining may be uneven and yellow, giving the packaging an undesirable appearance. In some cases, the pigmented white film may use a blocking layer containing a polymer, such as polyamide or ethylene vinyl alcohol copolymer (EVOH). These polymers can prevent food components from staining the white film. However, in some cases, it is desirable to avoid the use of polyamide and/or EVOH, as they add cost and complexity to the structure, as well as creating an overall film structure that is more difficult to recycle. SUMMARY [0006] This document discloses packaging films for retort processing that resist the production of stains that may occur due to food product components. The packaging films contain a white multilayer film, wherein the white multilayer film has a) a sealing region located on an exposed surface of the packaging film, b) a white region comprising a white pigment in an amount of 3.5% to 35% by weight and a propylene-based polymer, and c) a blocking region, wherein the blocking region is located between the sealing region and the white region. The sealing region and the blocking region each contain a propylene-based polymer and are each essentially free of white pigment. The combined thickness of the sealing region and the blocking region is at least 70% of the thickness of the white multilayer film. The packaged food product can be produced using the packaging film, and the white region of the multilayer film will stain less than similar conventional packaging films. [0007] Another embodiment of a stain-resistant packaging film for retort processing may include a white multilayer film having a) a sealing region located on an exposed surface of the packaging film, b) a white region, and c) a blocking region, wherein the blocking region is located between the sealing region and the white region. The white region comprises a propylene-based polymer and a white pigment in an amount of 3.5% to 35% by weight, wherein the sealing region and the blocking region each contain a propylene-based polymer and are each essentially free of the white pigment, and the combined thickness of the sealing region and the blocking region is at least 68.6 microns (2.7 mils). [0008] Another embodiment of a stain-resistant packaging film for retort processing has an outer exploration layer, a barrier layer, and a white multilayer film, wherein the white multilayer film has a first primary surface and a second primary surface. The white multilayer film has a sealing region which has a polypropylene-based polymer, wherein the sealing region is located on the first primary surface of the white multilayer film and on an exposed surface of the packaging film, and a white region, wherein the white region has a thickness which is 30% or less than the thickness of the white multilayer film and is located on the second primary surface of the white multilayer film. The barrier layer is between the outer exploration layer and the white multilayer film, the white region comprises a white pigment between 3.5% and 35% by weight, and the white multilayer film is otherwise essentially free of white pigment. BRIEF DESCRIPTION OF THE DRAWINGS [0009] Disclosure can be more fully understood by