Oxygen-scavenging containers

Abstract

A container providing effective oxygen-scavenging functionality, while having high L* color or low darkness. The container has at least one wall, wherein the wall comprises a populated area, and wherein the populated area comprises a film-forming polymer; and a population of particles comprising an effective amount of oxygen-scavenging particles, wherein the number of oxygen scavenging particles does not exceed a concentration of about (1×107 particles÷T) per cubic centimeter of polymer wherein T is the thickness of the populated area in mils; and wherein the change in the transmission Hunter L* of said wall is less than about 0.4 per mil of the container wall when compared to a control that does not contain oxygen-scavenging particles.

Description

CROSS-REFERENCE [0001] This application is a continuation of pending application Ser. No. 10 / 195,519 filed Jul. 16, 2002 which is a continuation in part of Serial No. 09 / 916,671, filed on Jul. 26, 2001 which is now U.S. Pat. No. 6,780,916 all of which are incorporated by reference in their entirety.BACKGROUND OF THE INVENTION [0002] Thermoplastic resins such as polyethylene terephthalate (PET) are commonly used to manufacture packaging materials. PET processed under the right conditions produces high strength articles with excellent gas barrier properties. Foods, beverages, and medicines can deteriorate or spoil if exposed to oxygen. To improve shelf life and flavor retention of products such as foods, beverages, and medicines, therefore, the barrier protection provided by PET is often supplemented with additional layers of packaging material or with the addition of oxygen scavengers. [0003] Adding a layer of gas barrier film is known as passive-barrier packaging. Ethylvinyl alcohol...

AI Technical Summary

Benefits of technology

[0011] In general the present invention provides a container comprising an effective amount of oxygen-scavenging particles and having high L* color or low darkness. More specifically, the present invention includes a container having at least one wall, wherein the wall comprises a populated area, and wherein the populated area comprises a film-forming polymer; and a population of particles comprising an effective amount of oxygen-scavenging particles, wherein the number of particles does not exceed a concentration of about (1×107 particles÷T) per cubic centimeter of polymer wherein T is the thickness of the populated area in mils; and wherein the change in the transmission Hunter L* of said wall is less than about 0.4 per mil of the container wall when compared to a control that does not contain oxygen-scavenging particles.

[0012] The iron or other oxygen scavenger is present in an amount sufficient to effectively scavenge oxygen and provide longer shelf life for oxygen-sensitive materials. The particle size of the particle population is thus optimized to provide effective scavenging activity, while minimizing the increase in darkness due to the oxygen scavenging particles.

Problems solved by technology

Foods, beverages, and medicines can deteriorate or spoil if exposed to oxygen.

Using distinct layers of differing materials is not preferred, however, because it adds cost to packaging construction and does not reduce the levels of oxygen already present in the package.

Sachets are generally limited to solid foods, where the sachet can be readily removed from the foodstuff and not accidentally ingested.

Construction of the sachets and the cost due to cumbersome nature of their introduction into the package result in increased costs.

However, containers requiring clarity and lack of color have heretofore been limited to organic type scavengers that maintain their clarity when placed in a separate layer in the wall of the container.

The use of the organic scavenger in a mono-layer or single-layer construction is limited by cost and regulatory constraints due to the nature of the organic scavenger or the by-products of the scavenging reaction.

Contributing to the cost are the logistical problems encountered with the use of organic type scavengers.

A disadvantage of this technique is that the polymer begins reacting with oxygen as soon as the package is made.

However, UV activation techniques are relatively expensive, and the initiators are often not regulated for use in food packaging.

Packages designed for beers and juices are specifically designed to prevent UV penetration, hence UV activation would not be practical for these containers which block UV.

The use of scavenging powders in clear packages has previously been limited by aesthetics, particularly haze and color.

In practice, this means a large number of small particles.

Unfortunately, previous attempts at preparing resin compositions comprising high levels of small particles of iron for use in clear packages have resulted in packages with poor optical properties.

Haze values for these bottles are generally high, clarity is lacking and the bottles are very dark.