US3616962A

US3616962A - Sealed container or cup

Info

Publication number: US3616962A
Application number: US884647A
Authority: US
Inventors: Robert E Phipps
Original assignee: Sweetheart Plastics
Current assignee: SWEETHEART PROPERTIES Inc; Solo Cup Operating Corp
Priority date: 1969-12-12
Filing date: 1969-12-12
Publication date: 1971-11-02
Anticipated expiration: 1988-11-02

Abstract

A plastic, disposable cup and lid including an easily broken seal consisting primarily of a narrow band of sealant such as paraffin which extends circumferentially about the mouth of the cup disposed between the mating regions of the cup and lip. The sealing band is applied in a thin film to the inner periphery of the cup or to the mating portion of the lid so that when they are assembled the paraffin band will be compressed slightly between and in intimate sealing contact with the mating surfaces of the cup and lid. This provides an effective seal, yet permits the lid to be removed with minimal effort.

Description

United States Patent 72] Inventor Robert E. Phipps West Campton, NH. [21] Appl. No. 884,647 [22] Filed Dec. 12, 1969 [45] Patented Nov. 2, 1971 [73] Assignee Sweetheart Plastics, Inc.

Wilmington, Mass.

[54] SEALED CONTAINER OR CUP 3 Claims, 3 Drawing Figs.

[52] U.S. Cl 220/60 R, 220/42 C, 229/43, 229/48 T [51] lnt.Cl 865d 5/68, B65d 43/10 [50] Field of Search 220/42 B, 42 C, 60, 60 R; 229/3.l, 5.5, 43, 48 T [5 6] References Cited UNITED STATES PATENTS 2,467,930 4/1949 Coyle 229/5.5

&\\\\\\\\\\\\\\ Primary Examiner-- George E. Lowrance Attorney-Wolf, Greenfield & Sacks ABSTRACT: A plastic, disposable cup and lid including an easily broken seal consisting primarily ofa narrow band of sealant such as paraffin which extends circumferentially about the mouth of the cup disposed between the mating regions of the cup and lip. The sealing band is applied in a thin film to the inner periphery of the cup or to the mating portion of the lid so that when they are assembled the paraffin band will be compressed slightly between and in intimate sealing contact with the mating surfaces of the cup and lid. This provides an effective seal, yet permits the lid to be removed with minimal effort.

PATENTEDmiv 2 Ian FIG.

IINVENTOR ROBERT PHIPPS ATTORNEYS SEALED CONTAINER R CUP BACKGROUND AND SUMMARY OF THE INVENTION A wide variety of disposable containers and lids have been developed and employed over the years, the more common of these containers being of paper or plastic construction. The lids frequently are formed from a thin, resilient plastic.

A number of factors may be considered when selecting paper or plastic as the container material. One of the important considerations is the material to be packaged. For example, when packaging some drinks in paper cups the drinks may acquire a "paper taste which, of course, is undesirable. This may be true particularly if the drink is to be stored in the paper container for a length of time before consumption. In these instances, a plastic cup is preferable in that no adverse taste develops. Many other situations may arise in which plastic is preferred over paper as the container material.

The fabrication of plastic containers is not free from difficulties. One such difficulty resides in the provision of an adequate seal between the mouth of the container and the lid. Obviously, if a lid is employed it must be sealed effectively to the mouth of the cup. Equally important, the lid should be capable of relatively simple removal, when desired. These desirable objectives, however, have not yet been attained. In fabricating containers of the type described, one of these objectives has been sacrificed for the other. Because of slight unavoidable dimensional variances between plastic cups and their associated lids, it has been found necessary to fabricate the cups and lids so that the lid must be pressed or force fitted into or about the mouth of the container. Although in some cases, this may provide an adequate seal, subsequent removal of the lid is made more difficult. In some instances ease of removal may be a critical factor. For example, when the containers are filled with milk for distribution to children in school cafeterias, the seal must be capable of being broken easily by a small child. It also must be effective to seal the cup and lid before use. The seal should preclude any liquid from passing between the cup and lid as well as retarding evaporation of moisture through the seal. It is among the primary object of my invention to provide a container and lid having an integral seal which satisfies the foregoing requirements.

Considerable efforts have been made in the prior art to develop manufacturing techniques for improving the uniformity of the dimensions for such containers and their lids. This has been important, particularly in regard to arrangements in which the lid is intended to be force fitted to the mouth of the container. The sealing arrangement disclosed avoids the necessity of an interference fit or direct force fit between the cup and the lid. These parts, therefore, need not be fabricated with the degree of dimensional accuracy previously required. The mouth of the cup and mating surfaces of the lid may be manufactured to provide a somewhat loose fit which is taken up by the band of sealant, such as paraffin.

In brief, the invention includes a container such as a conventional plastic cup, which may include a lid seat formed integrally about the inner wall of the container in proximity to the mouth of the container. The lid seat normally serves to limit the depth to which the lid may be pressed into the container. The mouth of the container terminates in a generally upstanding lip wall extending upwardly from the outer periphery of the lid seat. The region at the junction of the lid seat and lip wall defines a continuous circumferential corner. In accordance with the invention, the lid seat, lip wall and corner region is coated with a thin, paraffin film or other suitable sealant material which is compatible with the material to be packaged. When the lid is placed over the container, the paraffin film is sandwiched therebetween and contacts intimately the mating surfaces to effect the desired seal. As described more fully below, the seal precludes leakage yet presents little resistance to removal of the lid. Additionally, the tolerances between the lid and mouth of the container need not be controlled closely and, preferably, are somewhat slack.

Other objects and advantages of my invention will be apparent from the following detailed description thereof with reference to the accompanying drawings wherein:

FIG. 1 is a partly broken-away illustration of a combined container and lid sealed in accordance with the invention;

FIG. 2 is an enlarged sectional view of the mating region between the container and lid shown in FIG. I; and

FIG. 3 is an illustration similar to FIG. 2 showing a modified configuration for the container and lid.

FIG. I shows the invention as used in a conventional plastic cup 10 having a bottom wall 12 and upwardly extending cup wall 14, which terminates at the mouth 16 of the container. The cup may include a lid seat I8 formed integrally with the cup wall 14 and an integral upwardly extending lip wall 20, which terminates in a curled rim 22 at the upper edge of the container defining the mouth 16. Disposable cups of the character described may be fabricated from any number of plastic materials, such as polystyrene, which is formable easily to the desired shape for example, by a vacuum molding or other conventional process.

Disposable cups and lids of the type described have employed a variety of seating and sealing arrangements between the cup 10 and lid 24, indicated generally by the reference character. FIGS. 1 and 2 show one of the more common ar rangements in which the lid seat 18 is formed about the inner periphery of the cup just below the rim .22. The lid 24 may include a base portion 26, integral inner peripheral wall 28, circumferential flange portion 30 and depending skirt 32. The inner wall 28, circumferential flange 30, and skirt 32 define an annular recess 34 which passes over and about the curled rim 22 of the cup 10. The skirt 32 facilitates gripping of the lid 24 during removal. The lid seat 18 limits the depth to which the lid 24 may be inserted into the mouth of the cup 10. The lid bears against the lid seat 18 to enhance the seal between the lid and cup.

As mentioned above, it has been common practice to provide a fluidtight seal between the cup Ill and lid 24 by providing a direct interference fit between the inner wall 28 of the lid 24 and the lip wall 20 of the cup 10. The interference fit between the

walls

28 and 20, together with engagement of the peripheral marginal of the base 26 of the'lid 24 with the lid seat 18, provides the fluidtight seal between the cup and lid. The

walls

20, 28 generally are of a tapered configuration to provide a snug fit between the lid and cup which tightens progressively as they are pressed together. It does, however, present some difficulties in that the mating parts must be fabricated within close dimensional tolerances to provide the necessary interference fit. Additionally, considerable force and manipulation is required to remove the lid 24 to break the interference-fitted seal. This feature is a disadvantage particularly when the cup is to be used by children, invalids or the like who may not have sufficient coordination and manipulative skills to remove the lid easily without spilling any of the liquid or other material contained within the cup 10.

As shown in FIGS. 1 and 2, my invention is intended to overcome the foregoing difficulties simply by providing a film of wax or paraffin in a band about the inner surface of the cup in proximity to its mouth and in a substantial portion of the mating region between the cup and lid. In the preferred embodiment, the wax band 36 extends continuously about the mouth and is located along the lid seat l8, lip wall 20, and comer region 38 at the juncture of the lip wall and lid seat. The wax film may be only a few thousandths of an inch thick, but it should be noted that the thickness may be varied considerably depending on the dimensions of the cup and lid. It is important, however, that when the lid is inserted into the cup it will bear against the wax band. The mating surfaces of the lid and cup are sealed by the wax, which is sandwiched into intimate surface contact when the lid and cup are pressed together. Although the wax tends to flow as a result of the capping force, it should be noted that the effectiveness of the seal results primarily from the intimate and continuous contact of the wax with the mating surfaces of the cup and lid. The

seal is not affected materially by the presence or absence of an interference fit between the mating surfaces. Removal of the lid from the cup is simplified in that the user need only overcome the adhesive forces between the wax and plastic. It is unnecessary to overcome the resistance of interference-fitted surfaces.

My invention permits the manufacturing tolerances of such cups and lids to be relaxed. The mating parts and surfaces need not be fabricated with a high degree of dimensional precision to achieve the previously required interference fit. Obviously, this results in manufacturing economies.

The paraffin band may be deposited either on the mating surface of the cup or on the mating surface of the lid before they are assembled. It is important that the band is located so that when the cup and lid are mated the band will be interposed along a substantial portion of the interface between the mating parts.

H0. 3 shows my invention as employed in a cup having a modified mouth which receives a lid 24 in an undercut lid seat. This cup includes a conventional nesting ring 40 formed about the inner periphery of the mouth above the lid seat 18' to define an opening of reduced diameter, which presents a restriction to insertion of the lid 24 into the mouth of the cup. The lid 24 is similar to the lid 24 shown in FIGS. 1 and 2, except that the periphery of its base portions 26' defines an enlarged flange 42 which is greater in diameter than the diameter of the ring 40. In this arrangement the lid 24' is aligned with the mouth of the cup and then is pressed into the mouth with the enlarged flange 42 and ring 40 deforming resiliently to enable the enlarged flange 42 to be forced past the ring and into the circumferential groove 44, defined by the ring 40 and the lid seat 18. The ring 40 then bears against the inner wall 28' of the lid 24 and locks the lid in place. Because the enlarged flange 42 must be forced past the ring 40, it is preferred, in this embodiment, not to deposit the wax band on the lid to avoid the band from being scraped off as the lid and cup are mated. Instead, it is preferred to deposit the wax band on the lid seat 18' and lip wall 20' of the cup. The wax band cooperates with the mated cup in the same manner as defined above.

It should be noted that although the invention has been described as employed with a conventional cup having a lid seat or nesting ring, it may be practiced with a variety of disposable plastic containers which may or may not have con ventional seats or nesting rings. It is essential, however, in 4 practicing the invention that the wax band be arranged to engage substantial portions of the mating surfaces of the container and lid sufficient to the effect the desired, easily broken seal.

Additionally, even though it is not necessary to employ interference-fitted containers and lids, the invention may be practiced with such containers if desired. Separation of the container and lid is simplified by the presence of the wax film interposed between the mating surfaces.

Thus, I have provided an improved sealing arrangement which results in a number of advantages such as the ease with which the seal may be broken as well as the relaxation of heretofore strict dimensional tolerances required in the manufacture of containers and associated lids. A further advantage of considerable importance is that a container sealed in accordance with the invention results in greatly increased shelf life of a liquid or similar product having a water or other volatile component. The seal is highly resistant to the vapor of such water or volatile component. This retards spoilage of the product through evaporation and now has been found to at least double the conventional shelf life of some products.

It should be understood that the foregoing description of my invention is intended merely to be illustrative thereof and that other embodiments and modifications will be apparent to those skilled in the art without departing from its spirit. For example, although the sealing band has been described as formed from paraffin, other materials displaying appropriate sealing characteristics may be substituted.

1 claim: 1. A plastic container having a mouth receptive to a lid engageable with the internal surface of said container in proximity to the mouth thereof said container including a cup wall and a lid seat formed integrally with said cup wall in proximity to the mouth of said container, said container further including a lip wall formed integrally with said lid seat and extending upwardly therefrom said lid including a base portion, an integral inner wall of a configuration corresponding to that of said lid seat and said lip wall of said container and means for effecting an easily broken seal between said container and said lid comprising;

a film of paraffin extending, in a substantially continuous band, along the lid seat and said lip wall, said band being adapted to be interposed between corresponding mating regions of said lid and said lid seat and lip wall.

2. An article of manufacture as defined in claim 1 wherein said inner wall of said lid and said lip wall of said container are of a generally paralleling taper.

3. An article of manufacture as defined in claim 1 further comprising said container having a nesting ring of reduced internal diameter formed about the inner periphery of said cup 5 above said lid seat;

said lid having an enlarged flange formed about the periphery of its base portion, said flange being of greater diameter than said ring on said container;

said wax film being deposited on said lid seat and said lip wall.

Claims

1. A plastic container having a mouth receptive to a lid engageable with the internal surface of said container in proximity to the mouth thereof said container including a cup wall and a lid seat formed integrally with said cup wall in proximity to the mouth of said container, said container further including a lip wall formed integrally with said lid seat and extending upwardly therefrom said lid including a base portion, an integral inner wall of a configuration corresponding to that of said lid seat and said lip wall of said container and means for effecting an easily broken seal between said container and said lid comprising; a film of paraffin extending, in a substantially continuous band, along the lid seat and said lip wall, said band being adapted to be interposed between corresponding mating regions of said lid and said lid seat and lip wall.

3. An article of manufacture as defined in claim 1 further comprising said container having a nesting ring of reduced internal diameter formed about the inner periphery of said cup above said lid seat; said lid having an enlarged flange formed about the periphery of its base portion, said flange being of greater diameter than said ring on said container; said wax film being deposited on said lid seat and said lip wall.