Receptacles – Closures – Removable closure retained by adhesive or fusion means
Reexamination Certificate
2000-08-03
2002-10-08
Young, Lee (Department: 3727)
Receptacles
Closures
Removable closure retained by adhesive or fusion means
C202S242000
Reexamination Certificate
active
06460720
ABSTRACT:
FIELD OF THE INVENTION
The invention relates broadly to containers, and in particular relates to a container having a peel-away lid with a dual seal, and a method for double-sealing a peel-away lid to a container.
BACKGROUND OF THE INVENTION
Many types of food products, both liquid and solid, are packaged in containers with peel-off lids. Such containers are often designed to hold single portions of items such as condiments and toppings, and are thus referred to as “portion cups.” Portion cups are commonly found in restaurants and contain such products as margarine, sour cream, and salad dressings. Solid materials that may be packaged in portion cups include ground pepper and various other seasonings. Portion cups are available in various sizes matched to the normal portion of the materials they are designed to contain. The container itself is generally formed of a plastic material, and may be molded in many shapes, including cylindrical, rectangular, and frustoconical varieties.
Portion cups have become popular because they may be produced relatively inexpensively while offering great convenience to the consumer. Such containers may be easily opened without the need for tools or opening devices. Generally, such containers are formed with a lip or flange extending laterally outward from the open top, to which the lid is sealed with some type of adhesive. The lid generally includes a tab or other handhold portion that extends beyond or above the lip. By gripping the tab and pulling back across the top of the lid, the consumer may easily open the container without spilling its contents.
One of the chief difficulties encountered in designing containers with peel-off lids is the maintenance of a consistent seal strength for all such containers produced. Numerous factors may affect the seal strength for the lids of such containers, such as the temperature at which the seal is made, the pressure applied to the lid during the sealing process, and the particular properties of the adhesive used. When a seal is formed that is too strong, the container becomes difficult to open, and may lead to the consumer using a knife or other potentially dangerous methods of reaching the contents inside. If the seal strength is too weak, then the container may leak during shipment or storage. Rough handling during shipment is a common problem for containers of this sort, as they are most often dropped into large boxes in groups of several hundred with no special padding or packaging to protect them from contact with other containers. If a container spills during shipment under these conditions, the entire box of product may be ruined as the contents of one or a few containers spills onto the other containers. Various environmental factors such as temperature and humidity may weaken seal strength during storage even when the seal strength was within specified tolerances at the time of manufacture. Consumers will reject a container that is not properly sealed, and the defect may reflect poorly on the food vendor that offered the product to the consumer.
Still another problem encountered in sealing containers with peel-away lids is that some portion of the packaged product may be present on the lip of the container prior to seating of the lid during the sealing process. Liquids may splash or spill onto the lip of such containers during filling, and powders or granulated materials may settle onto the lip of such containers in the form of a dust. This problem is exacerbated by the high speed at which the filling operation must proceed in order to keep production costs low. When a lid is applied to a container when such material is present on the container's lip, the seal in that region of the lip will be poor and the container is far more likely to leak during shipment or storage.
The prior art includes various attempts to improve the durability and consistency of the lid seal for peel-off lid containers. For example, U.S. Pat. No. 5,316,603 to Akazawa et al. teaches a container having “microdents” along a sealing layer in the flange or lip portion of the container, or along the sealing portion of the lid. These microdents are arranged in various patterns in the form of dots along the sealing surface between the lip and lid of the container.
U.S. Pat. No. 5,979,748 to Drummond et al. teaches a tubular container with a lid having an adhesive layer; the lid is sealed using heat and pressure. As the lid is pressed onto the lip of the container, the adhesive in the adhesive layer is pressed outward from the center of the lip, forming an outer adhesive bead and inner adhesive bead from the adhesive build-up at the edges of the lip. A thin layer of adhesive may remain between the lid and container lip, or the container and lid may Make contact in the center of the lip, such that the entire seal is formed by the inner and outer adhesive beads.
U.S. Pat. No. 4,379,008 to Gross et al. teaches a method for attaching together two pieces of cardboard using a heater with truncated pyramid-shaped projections. One piece of the cardboard has an adhesive layer that contacts the other piece. As the heater is pressed onto the upper piece of cardboard, pressure from the projections causes adhesive to flow outward from beneath the projections and collect in areas between the projections.
U.S. Pat. No. 4,659,405 to Walter teaches a lid and container seal wherein an incompressible rib is formed along the lip of the container. The lid has an adhesive layer that forms a seal with the rib, but the adhesive does not necessarily contact the flat portion of the lip, and no seal with the flat portion of the lip is formed. The rib is sealed to the lid with adhesive, and does not deform during sealing. The pressure applied in this sealing process is not great enough such that the rib pushes through the adhesive layer and comes into contact with the portion of the lid beneath the adhesive layer.
U.S. Pat. No. 4,961,513 to Gossedge et al. teaches a container with a lip having a plastic upper surface and a lid with a plastic lower surface. The lid and container lip are heat sealed together, forming two “ears” of material at the outer and inner edges of the seal. The “ears” consist of a plastic core formed of material from the lip which is joined to the lip by a thin “root,” and an envelope encasing the core formed of material from the lid.
None of the prior art methods described above adequately overcome the problems of forming a consistent seal on a container, particularly when the container may contain overflow of product on the container lip. This problem, particularly acute when solid materials are to be placed in the container, will interfere with each of these sealing methods, resulting in a weak seal when material is present. What is desired is a method for sealing a peel-off lid on a container such that a tight seal is formed even when material may be present on the lip of the container during the sealing process.
SUMMARY OF THE INVENTION
The present invention overcomes the limitations of the prior art through a double sealing method to provide a consistent seal even when the lip of the container may be contaminated with overflow product. The container comprises a lid and a cup, with the cup having a lip with a raised sealing bead that runs along its length. The lid includes an adhesive layer on its lower side. The raised sealing bead is compressible, which allows a weld to form between the bead and the lid when the lid is pressed into place, while at the same time an adhesive seal is formed between the lid and the remaining portion of the lip. Thus the lid is sealed to the container both by the weld between the sealing bead and the lid, and by the adhesive bond between the lid and the remaining portion of the lip.
To attach the lid to the container according to the present invention, the lid is positioned over the cup and pressed into place while heat is applied. The heat causes the adhesive to bond the lip to the lid. The raised bead, however, will compress and deform under pressure, thereby stretching adhesive on the lid d
Jodts, Jr. Victor J.
Lord Thomas A.
Massey Samuel M.
Phillips Richard
Creative Foods, LLC
Dougherty J. Charles
Ngo Lien
Young Lee
LandOfFree
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