Packaging

Abstract

The carton and package provide a heat-releasable connection for a closure for a package which is to be heated for use wherein the heat sealed connection will become ineffective when subjected to boiling water conditions. In one form, the closure is a lid for a tray type container. In the second form the closure is a small closure for a small aperture in the lid wherein the size of the aperture is such that it will act as a one-way valve when the package is heated underneath the surface of the water to allow escape of steam or vapor under pressure and to prevent the ingress of water.

Description

DESCRIPTION OF THE INVENTION

The present invention relates to packages preferably of the self-opening type and includes a package such as a tray or carton having flange means around its open end, the material of the tray being of a boilable character such as, for example polyethylene, and the lid for the carton or tray being also of boilable character and comprising paperboard, for example, coated with a suitable sealant. The present invention also relates to methods of cooking food in self-opening type packages under water by providing for escape of steam or vapor under pressure and for preventing ingress of water.

It is a general object of the invention to provide an improved carton or package for various food products to be sold for example frozen food products wherein a closure of the package is loosened or released in response to heating as an incident to the heating of the material within the tray of the package.

Another object of the invention is to provide a lid which will become loosened at temperatures below the boiling temperature of water.

A further object of the invention is to provide an improved carton or lid of the above character wherein the sealant employed which melts to loosen the lid on the carton or tray is placed directly on the paperboard without any intermediate layer of material so as to be absorbed at the time of boiling.

Still another object of the invention is to provide a food package for heating by boiling under water in which a small aperture is provided in the lid for escape of steam or vapor under pressure which aperture is normally closed by small closure or valve member heat sealed over the opening.

A still further object of the invention is to provide a carton or food package of the above character wherein the size of the aperture is such that the small closure over the aperture will act as a one-way valve to prevent ingress of water while permitting escape of gases under pressure.

The above and other objects and advantages of the invention will be apparent from the following description of a preferred embodiment thereof as illustrated in the accompanying drawings in which:

FIG. 1 is a perspective view of a closed package;

FIG. 2 is an enlarged fragmentary sectional view taken in a plane indicated by the line 2--2 in FIG. 1;

FIG. 3 is a fragmentary perspective view of a modified form of the invention;

FIG. 4 is a fragmentary sectional view taken in a plane indicated by the line 4--4 in FIG. 3; and

FIG. 5 is a fragmentary perspective view of a modified form of the invention.

Referring to FIGS. 1 and 2, a conventional tray 10 illustrates the type of package which may be employed and this tray 10 may be of polyethylene, or other plastic materials, for example, and of a rigid or semi-rigid construction. This tray 10 is provided with a flange 11 extending around the four sides thereof and forming flange means adapted for connection to the planar type lid 12 which may be of paperboard, for example, coated or lined with polyethylene or any suitable sealing material. If desired, the board may be uncoated or it may be selectively coated at different areas with polyethylene or a heat sealing coating as described below. Also laminations of paperboard and suitable plastics may be employed.

Preferably, the lid 12 is heat sealed to the flange means 11 by means of a heat sealing coating 13 as shown in FIG. 2, which is meltable at or below the temperature of boiling water and preferably below this temperature. This may be, for example, an "Alathon" petroleum and wax material produced by the Continental Oil Company of Ponca City, Okla., under their formula No. PPDX-122. Any suitable heat sealing wax or other sealing composition may be employed which will melt at or below 212.degree. F. When the closed tray is placed in a container with water part way up the sides of the tray, and subjected to a boiling treatment to heat the contents of the tray the heat generated will loosen the seal 13 so it becomes ineffective against the gases within the package due to the formation of steam and allow escape of these gases. Also the lid can be readily lifted off from the flange means 11 so as to provide access to the package. Usually the heat sealable compound referred to herein will release at about 170.degree. to 180.degree. F.

The lid may be coated first with polyethylene as a barrier and on this a low melt coating can be applied for release of the lid from the tray such as the PPDX-132. Preferably however the sealant such as PPDX-122 is placed directly on the paperboard without an intermediate so that as it melts it will absorb into the board.

Referring to FIGS. 3 and 4, a tray 10 of the character referred to in the description of FIG. 1 is provided with a lid 12a which also may be of similar construction to the lid 12 of FIG. 1. The lid 12a is provided with a small aperture 16 at a convenient location and this aperture is normally closed by a small lid or closure 17 which is secured to the lid 12a about the aperture by a ring of the adhesive 18 of the same character as adhesive 13 described with respect to FIG. 2. Preferably, this aperture 16 is of sufficiently small cross section so that the force of the steam pressure or vapor pressure within the package 10 is insufficient to break the softened seal around the edge of the carton but merely to partially lift the closure 17 so that it acts as a one-way valve providing for escape of steam or vapor under pressure from within the carton and preventing the ingress of a liquid such as water into the contents of the carton where the carton is submerged during the heating step. In other words, this construction provides a method of heating the contents of the tray or carton package by submerging it in water and the package will effectively remain closed as far as leakage of water to the inside of the package is concerned. Subsequently, the package can be removed from the water and the lid 12a lifted off of the tray 11, the heat sealable material 13 being sufficiently heated to allow easier removal of the lid 12a.

We have found that a diameter of about one-sixteenth to one-eighth inch or less of the aperture 16 will perform satisfactorily in the keeping down the total force against the tray 12a by relieving the pressure underneath the lid 12a. At the same time the seal 18 retains sufficient strength around this aperture 16 to effectively keep the small closure 17 in place although loosened to allow escape of steam or vapor under pressure.

Referring to FIG. 5 the lid 12a is provided with special closure 17a which has a weakened portion in its periphery adjacent to the aperture 16, and this weakened portion is formed by a radial cut 19 which extends from the outer edge of the closure 17a inwardly to a point adjacent the opening or aperture 16 but preferably not intersecting this opening. This weakened portion of the closure can be selectively used to control the pressure at which the seal provided by the aperture 16 and the closure 17a will let go or partially let go to allow the escape of gas vapors and/or steam from the interior of the package.

While we have shown and described certain preferred embodiments of the invention it is apparent that the invention is capable of variation and modification from the forms shown so that the scope thereof should be limited only by the scope of the claims appended hereto.

Claims

We claim:

1. A package comprising a container body having an opening, a lid for the opening, flange means surrounding the opening, a sealed connection between said lid and the flange means comprising a coating meltable at or below the temperature of boiling water, a small opening in said lid, a closure for said small opening, heat sealable material forming a sealing connection between the closure and the lid, both said sealed connection coating and said heat sealable material forming the sealing connection being of heat meltable or softening material and said closure for said small opening forming a one-way valve when subjected to softening action so as to permit egress of gas under pressure and to prevent ingress of water.

2. A package comprising a container body having an opening and a lid for the opening, a small aperture provided in the lid and a closure for said small aperture, said closure having integrally formed means providing for the escape of gas under pressure from within the package and preventing ingress of water past said closure, and a sealed connection separate and apart from said integrally formed means between said lid and closure in the form of a coating of material heat meltable or softening at or below the aperture of boiling water.

3. A package comprising a container body having an opening and a lid for the opening, a small aperture provided in the lid and a closure for said small aperture, said closure having integrally formed means providing for the escape of gas under pressure from within the package and preventing the ingress of water past said closure, and said integrally formed means comprises a weakened portion.

4. The package as defined in claim 3 including a sealed connection between said lid and closure in the form of a coating of material heat meltable or softening at or below the temperature of boiling water.

5. A package comprising a container body having an opening and a lid for the opening, a small aperture provided in the lid and a closure for said small aperture, said closure having integrally formed means providing for the escape of gas under pressure from within the package and preventing ingress of water past said closure, said weakened portion comprises a slit formed in said closure and extending to a point adjacent to said small aperture.

6. The package as defined in claim 5 including a sealed connection between said lid and closure in the form of a coating of material heat meltable or softening at or below the temperature of boiling water.