METHOD OF HIGH-TEMPERATURE TREATMENT OF ARTICLE USING VENTED RECLOSABLE PACKAGE

RELATED PATENT APPLICATION

This application claims the benefit, under Title 35, United States Code, § 119(e), of U.S. Provisional Application No. 60/837,559 filed on August 14, 2006.

BACKGROUND

This invention generally relates to high-temperature vented reclosable bags, and in particular, to reclosable bags.

Historically, reclosable bags having press-to-close or slide-to- close reclosable feature were designed for food storage applications such as non-refrigerated and refrigerated storage. These bag products were manufactured from a combination- of polyethylene resins with a reclosable feature. Such reclosable bag products were not designed for high-temperature applications; for example, they are not microwavable.

The uses and applications for reclosable bag technology are continually expanding. There is a need for a reclosable bag or pouch designed for high-temperature applications.

BRIEF SUMMARY

Disclosed herein are methods of sterilizing or cleaning an article and reclosable bags that can be employed in those methods. The reclosable bags are of a type made of flexible material able to withstand high temperature, for example, equal to or greater than the boiling point of water, and are vented to allow the relief of pressure buildup inside the bag during heating.

The disclosed treatment methods have application in the sterilizing or cleaning of household items, such as breast milk pump parts for

nursing mothers, and medical instalments for hospital, dental and military applications.

One aspect of the invention is a method of treating an article, comprising the following steps: (a) placing an article inside a reclosable bag having at least one vent; (b) closing the bag with the article inside; and (c) heating the bag to a high temperature.

Another aspect of the invention is a method of treating an article, comprising the following steps: (a) placing an article inside a reclosable bag having at least one vent; (b) closing the bag with the article inside; and (c) exposing the bag and its contents to radiation from an energy source.

A further aspect of the invention is a bag comprising a receptacle having an interior volume and a mouth, and a reclosable feature that closes the mouth of said receptacle when in a reclosed state, wherein the receptacle comprises front and rear panels each having two sides, a top and a bottom, wherein marginal portions of one side of the front panel are sealed to corresponding marginal portions of one side of the rear panel to form first and second side seals, the first and second side seals being separated by an unsealed zone wherein the marginal portions of the one side of the front panel and the one side of the rear panel are not sealed together, the unsealed zone forming a vent that communicates with the interior volume.

Other aspects of the invention are disclosed and claimed below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a drawing showing a front view of a vented reclosable bag in accordance with one embodiment of the invention.

FIG. 2 is a drawing showing a sectional view of a vented reclosable bag in accordance with one variation of the embodiment shown in FIG. 1.

Reference will hereinafter be made to the drawings in which similar elements in different drawings bear the same reference numerals.

DETAILED DESCRIPTION

The treatment methods disclosed herein employ reclosable bags that are designed to withstand the particular temperature and pressure conditions attending those treatment methods. Each reclosable bag is made of flexible material, such as polypropylene, plastic lamination films or other high- melting-temperature flexible material. Each reclosable bag has a reclosable feature, e.g., a plastic zipper comprising a pair of zipper strips having mutually interlockable closure profiles. The plastic zipper may be of the press-to-close variety or the slide-to-close variety. In the latter category, the slider may be of the type that closes an underlying portion of the zipper as it moves in either direction or it may be of the type that closes an underlying portion of the zipper when it travels in one direction and opens an underlying portion of the zipper when it travels in the opposite direction. Also each reclosable bag has one or more vents for pressure relief.

In accordance with one treatment method, a reclosable feature of a reclosable bag is opened and an article to be sterilized or cleaned is inserted through the open mouth and placed inside the bag. An amount of water is also placed inside the bag, e.g., by pouring water from a bottle and into the bag. Preferably the water is distilled. Naturally the water will accumulate at the bottom of the bag due to the effect of gravity. The reclosable feature on the bag is then closed. After the bag is closed, the bag and its contents are exposed to a source of energy that raises the temperature inside the bag to, for example, at least the boiling point of water. For example, the bag and its contents may be placed inside a microwave oven, which oven is then set to cook the bag and its contents to the extent that the water inside the bag boils. As a result, the article inside the bag is exposed to superheated or boiling water that sterilizes or cleans the article. During this process, the pressure buildup inside the bag is relieved by the release of steam through one or more vents formed in the

reclosable bag. The pressure relief prevents the bag from bursting or otherwise having its integrity compromised. Preferably the bag is cooked in the microwave oven until substantially all of the water inside the bag has evaporated. After cooling, the sterilized or cleaned article inside the intact bag can be stored for future use.

Other methods of heating the bag and its contents may be used, such as baking in a gas or electric oven.

FIG. 1 depicts one embodiment of a high-temperature vented reclosable bag suitable for use in sterilizing or cleaning articles. This high- temperature vented reclosable bag may be used for sterilization or cleaning of: (1) consumer products, including household items (e.g. breast milk pumping parts for nursing mothers), or (2) industrial products, including medical instruments used on hospital, dental, and military applications.

The bag shown in FIG. 1 comprises a receptacle 2 made of flexible material, such as polypropylene film, plastic lamination film, other higher-melting-temperature material, or a combination of two or more of the foregoing types of flexible material. A front panel 6 and a rear panel (not shown in FIG. 1 ) made of flexible high-temperature material are joined together at the bottom and two sides by conduction heat sealing to form the receptacle 2 having an interior volume and a mouth in which a reclosable feature 4 is installed. The bottom heat seal is indicated by reference numeral 14 in FIG. 1. The side heat seals are respectively indicated by reference numerals 10 and 12. The areas of overlap between the reclosable feature and the side heat seals 10 and 12 are indicated by reference numerals 16 and 18 respectively. In the case where the reclosable feature is a flanged zipper or a string (i.e., flangeless zipper), the areas 16 and 18 typically correspond to zones where the zipper strips are joined to each other and the closure profiles are flattened by thermal crushing or ultrasonically stomping in well-known manner.

Each of side heat seals 10 and 12 comprises two portions separated by a respective gap in the side heat seal. The gap in the side heat

seal 10 forms a vent 20 that allows communication between the interior and exterior of the receptacle 2. Likewise the gap in the side heat seal 12 forms a vent 22 that allows communication between the interior and exterior of the receptacle 2. The vents can be formed by providing gaps In the heated side sealing bars typically used to form side seals 10 and 12.

Although the embodiment shown in FIG. 1 has two vents, one in each side of the bag, the broad scope of the invention encompasses the use of a single vent on one side only. It also encompasses the use of more than two vents. Preferably, the vents are placed above the water level inside the bag. The receptacle may be provided with a line indicating the optimum level to which the receptacle should be filled with water.

A person skilled in the art will readily appreciate that vented reclosable bags suitable for use in the treatment methods disclosed herein may have various constructions. The side seals may be formed by a hot knife, impulse sealing or conduction heat sealing. Preferably the vents for pressure relief are located away from the bottom of the bag. The vents can be formed by short slits or small perforations in the front and/or rear panel.

The person skilled in the art of manufacturing reclosable bags on a machine would readily appreciate that instead of forming the bag from two separate webs of plastic film joined together on three sides, the bag can be formed from a single web of film that has been folded. In the completed bag, this fold will form the bottom of the bag, while the two side seals are formed by conduction heat sealing. Alternatively, the bottom of the bag could be gusseted or stand-up gusseted.

FIG. 2 is a sectional drawing depicting the case wherein the bag has a fold at the bottom and the reclosable feature is a flexible zipper comprising a pair of plastic flanged zipper strips 24 and 26 having mutually interlockable male and female closure profiles respectively. In this example, the male zipper strip 24 is heat sealed to the front panel 6 and the female zipper strip 26 is heat sealed to the rear panel 8, these heat seats 28 and 30 be

indicated by x's. Alternatively, the zipper strips may be flangeless. Optionally, the zipper could be operated by a slider mounted thereto. The structures of various slider-operated plastic zippers are well known in the art and will not be described in detail herein. The vents in the side seals are not shown in FIG. 2.

While the invention has been described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for members thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation to the teachings of the invention without departing from the essential scope thereof. Therefore it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

As used in the claims, the term "article" includes, but is not limited to, an item, utensil, tool, instrument, device, appliance, or other household or industrial product.