CA1150193A

CA1150193A - Plastic lid for containers

Info

Publication number: CA1150193A
Application number: CA000385144A
Authority: CA
Inventors: Hubert Van Melle
Original assignee: Amhil Enterprises Ltd
Current assignee: Amhil Enterprises Ltd
Priority date: 1981-09-03
Filing date: 1981-09-03
Publication date: 1983-07-19

Abstract

PLASTIC LID FOR CONTAINERS
ABSTRACT OF THE DISCLOSURE

A lid for containers, usually beverage cups which may be for hot beverages or cold beverages, is provided, having a cavity adapted for seating against the bead of the container. A skirt extends downwardly from the cavity, having a number of outwardly extending projections formed in it, each of the projections having a substantially rectangular appearance with a vertical face and vertical side walls. The portions of the skirt between the outwardly extending projections extend inwardly to form a discontinued waist having an undercut which defines the cavity in the waist portion;
the cavity being defined by a higher and less inwardly extending undercut over the top portion of each of the outwardly extending projections. Beneath the projections and the waist portions between them there extends outwardly and downwardly a lower band portion;
below which may be a vertically extending wall, and which may have an outwardly turned lip at its bottom.
The lid is generally formed of thin, flexible plastic, such as polystyrene usually by a thermoforming process on male moulds, from which the lid may be easily stripped. The lid has a lower stacking height and is less likely to be stripped from a cup by rubbing against another lid on another cup.

File No. PAT6096

Description

FIELD OF THE INVENTION:
This invention relates to a lid Eor containers, and in particular lids for beverage containers. The lid of the present invention may be applicable for use with containPrs designed for holding hot beverages or cold beverages, but is more particularly intended for use wi~h cold beverages. rhe lid of the presen~ invention is in~ended to be formed using vacuum thermoforming process, from thin, flexible plastic sheet material, usually polystyrene.
BACKGROUND OF THE I~VENTION:
Disposable lids for containers such as beverage cups, food cups, and the like, are well known. Usually, when such lids are disposable, they are made from an inexpensive thin, flexible plastic material, such as polystyrene; which, however does n~t have a significant amount of elasticity. Therefore, in order to be able to be placed over and removed from the bead of a container, the lids must be designed ~n such a manner that they have a so-called "garter-spring" configuration. This 20 configuration compr~ses a plurality of convolutions or corrugations, or other protruberances, formed on the skirt portion of the lid.
By so configurlng cup lids and lids for food cups and the like, such lids may be applied to and removed from the container at least once, after which they are usually disposed of. However, the llds must alfio first be stripped from the 27 mould on or in which they are made.

.S~

Certain difficul~ies have arisen from previous designs, including difficulties in stripping the lids from moulds, causing deformations or stress failure in the material of the lids, or requiring special stripping st~tions which add to the expense of lid production and which may slow down the process of production.
Moreover, even though a lid may be designed to fit a cup having a particular dimension, the manufacturing tolerances by which such cups or other containers may be produced are such 10 that the diameter of the rim or mouth of the container, or the size of the bead formed at the outer edge of the container, may vary significantly~ so that lids designed to fit such containers having a nominal size may not, in fact, do so. This may result in a container wh~ch is much inclined to leakage around the lid, and very often results in an inadvertent stripping or dislodging of the lid from the container mouth, partlcularly when more than one container, each having its own lid, may be placed in a bag or other receptacle for carrying.
Still further, the space taken for shipping and storage of 20 prior art lids kas sometimes been quite significant. For example, food vendors or the like may sometimes find that the designated space that they have for lid storage, in which they expect to store a specific number of lids as received from the manufacturer, may not be quite enough space; or as a corollary, either the producer of the lids or the food vendor may wish to store more lids in a given amount of space. The present 27 invention provides a lower stacking height, so that each lid occupies a somewhat smaller volume, which may be significant when storage of lids in amounts of thousands or even millions or such lids is considered.
Certain prior paten~s are par~icularly indicative of the kinds of lids in respec~ o which the present invention provides an improvement; particularly as to ease of stripability from moulds, lessening of the likelihood of inadvertent removal from a container when placed thereon, and accommodation of a wider tolerance of container siz s of a nominal size.
Included among the prior art patents of interest is ALDINGTON, United States Patent 2,922,563, issued January 26, 1960. That patent is specifically concerned wlth the provision of a container closure which has a downwardly and outwardly flared skirt which is then corrugated, and above and inwardly of the skirt there ls located a cavity for fitting to the bead of a container. ALDINGTON is also concerned with stackability, by which lateral shifting of stacked lids relative to each other is precluded. However, lids of the sort taught ~n ALDINGTON are formed in female dies or moulds, and may be 20 easily dislodged from a container on which they are placed if they are jostled agalnst other such lids on containers.
NEGORO, United States Patent 3,065,875, issued November 27, 1962, teaches a snap-on plastic cup lid having a garter-spring flexibility in the skirt portion to permit fitting to a cup bead, but which only accommodates and fits to the cup bead discontinuously around the circumference thereof 27 by virtue of projections formed in the skirt portion.
Yet another approach is tàken by BREWER, United States ~L~ S~ 3 Patent 3,583,596, issued June 8, 1971 - reissued as Unlted States Patent Re28,797, on May 4, 1976, with the same disclosure. BREWER provides a lid having a conical skirt in which is formed a plurality of spaced flutes, which vary in dimension from top to bottom~ and whlch provide telescopic rigidity to ~he skirt with sufficient conical strength to adapt to the bead of the cup. BREWER is particuarly concerned with nesting and s~acking, and provides three spaced stacking lugs in the ~entral panel for that purpose.
A different approach, particularly to mounting the plastic container closure on the container, is taken by BLAMCHARD, United States Patent 4,026,459, issued May 31, 1977.
BLANCHARD provides a series of pro~ruberances around the outside wall of the container, which thereby provides a discontinuous bead to grip the rim of the cup or container.
Each of the protruberances may be disengaged from the rim of the container, without causing displacement of adjacent protruberances from engagement with the rim.
None of the above, nor any other known flexible plastic 20 lid for containers for food or beverages, whether hot or cold, provides a lid which has a generally central panel and a circumferentially extending cavity which opens downwardly and inwardly to receive the bead of the container to which the lid is to be fitted~ where the skirt portion which extends downwardly from the cavity has a plurality of outwardly p~o~ o~5 extending ~ r~ es~ , each of which has a substantially 27 vertical face and substantially vertical side edges and side walls which extend inwardly from each face of each ~rojection, and where ~he portions of the skirL between the outwarclly extendino projec~ions, extend inwarclly to form a discontinuecl waist which has an undercut clefinin~ the cavity in the waist portions. Each of the outwardly extending projections, and each of the discontinued waist portions between them, all terminate at their lower portlons in a downwardly and outwarclly slopecl lower bancl portion. the lower band portion may, in turn, terminate at a su~stantially vertically ciisposed downwardly extending wall portion, which 1~ may generally have an outwardly turned lip at its bottom. All of the outwardly extending projections terminate at a respective upper discontinued band portion which extends inwardly and upwardly from the upper eclge of each of the vertical faces of the projections, each of which terminales at the cavity at an upper unclercut which is higher ancl less inwardly extencling than the undercut of the waist portions, but whicll also defines the cavity.
Thus, the present invention provides a thermoformed, thin plastic lid for containers, generally formed of a plastic which has no significant arnount of inherent elasticity, and which has a continuous cavity formed at its upper periphery in such a manner that the cavity can accommodate the beads of different sized containers which have a given nominal size; i.e.~ the bead-receiving cavity of lids of the present invention may accornmoclate a wicle tolerance of bead size and mouth diameter of containers for which any such ]id is nominally intendecl to be 27 used as a closure therefor.
Moreover, the present invention provides lids of the sort ~s~
spoken of above, which have a lower stacking height ~han prior art lids, thereby permitting more lids to be stored in the same spaceO
Still further, th~ presen~ invention provides lids which may be formed on male moulds, a process which is somewhat less expensive and more positi.ve as to the interior dimensions of the lid -- which are the dimensions intended to be fitted to the rim or mouth of a container __and yet the lids of the present invention are easily stripped from the moulds on which they are made.
Still further, the present invention provides lids which are less likely to be disengaged from the container on which they are fitted by jostling against similar lids on similar containers.

BRIEF DESCRIPTION OF THE DRAWINGS:
~ ~ _ .
The above features and objects of the present invention will become more evident, and are dis~ussed in greater detail hereafter, together with o~her advantages of the present 20 invention, in association with the accompanyirlg drawings, in which:
Figure 1 is a perspective view of a lid according to the present invention fitted to a typical container;
Figure 2 is a partial plan view from above~ looking in the direction of arrows 2-2 of Figure l;
Figure 3 is a partial cross-section of a lid, taken on 27 line 3-3 of Figure l;
Figure 4 is a partial cross-section similar to Figure 3 but ~s~

taken on line 4-4 in Figure 1~ and, Figure 5 is a partial cross-section showing a typical stacking arrangement of lids according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS:
As noted, the present invention provides a lid 10, which is intended for use with a container 12. The lid 10 is formed of thin, flexible plastic material, usually polystyrene. If the lid is made of polys~yrene plastlc material, tha~ material is such that it does not generally have any significant amount of elasticity, but is flexible. Indeed, the lid 10 of the present invention is generally intended for manufacture using a vacuum thermoforming process on male moulds 9 by which the inside dimensions of the lid may be more particularly defined and controlled. This is diseussed in greater detail hereafter.
The container 12 may generally be a paper container or tub, intended for use with hot or cold beverages, milkshakes or foodstuffs such as salads or the like. Usually, such containers are formed of paper and may have a plastlc or wax coating or lining, and have a bead formed on the outer edge of their upper periphery or mouth3 such as the bead designa~ed 14 in Figures 3 and 4.
The lid 10 has a generally central panel 16, in which there may be formed a vent or cross cut opening 18, through which a drinking straw may be inserted.
p~Llr; p~ ,a ~1~
27 Specifically, the lid 10 has a ~trc~-~ere-~L~Iy extendi.ng cavity 2~ whicll is i~ol-me(l at the upl)er and outer extremity of the lid, for receiving the bead 14 o~ the container 12 to which the lid is to be fitted. The cavity 20 o~ens downwardly and inwardly, in order to receive the bead 14.
~ leans such as an upwardly extendin~ circular rim 22 and an inner skirt 24 may be provided, for connecting the cavity 20 to the central panel 16; but the precise configuration is immàterial to the present invention.
The outer portion of the lid 1~ comprises a skirt, generally designated at 26, which extends downwardly ~rom the cavity 20. Formed in the skirt 26 are a plurality of outwardly extending projections 2$, each of which has a substantially rectangular ~ront face, de~ined by verticaL side eclges and inwardly extencling vertical side walls 30. Between the outwardly extending projectio-ns 28 there are portions 32 oE
the skirt 26, which extend around the lid 10 in the skirt portion 2G to form a discontinuecl waist indicated at 34. I`he waist 34 ~orms an undercut which thereby defines the cavity 20 in the waist portions 32.
The outwardly extending projections 2~ and the discontinued waist portions 32 all terminate at their lower portion in a downwardly and outwardly sloped lower band portion 36. The lower band portion 36 may, in turn, terminate at a substantially vertical, downwardly extending wall portion 3~;
which, in turn, may terminate at an outwardly extending lip 4~.
Each of the outwardly extending projections 28 terminates 27 at a discontinuecl band portion 42, which extends inwardly and upwardly from the vertical outer face o~ each outwardly exterldiTlg projection 2~. ~ach barl(l portion 42 terminates at the cavity 2~ at an undercut 44, which is higher and less inwardly extending than the undercut 34, and which also defirles the cavity 2~ in each region of the skirt portion 26 over the outwardly extending projecti.ons 2~.
~ igure 3 is taken through a waist portion 32, so as to indicate the relationship of the cavity 2~ and the undercu~ 34 to the bead 14 of a container 12. Like~ise, FigJure 4 is taken through an outwarc31y extending projection 2$, to demonstrate 1~ the relationship of the undercut 44 to the bead 14 and container 12.
Very eviclently, as a lid 10 is being placed over the bead 14 oE the container 12, it flexes in each undercut portion 34, sufficiently that the li.d may be pushed downwardly over the bead, so that it then accommodates the bead due to its flexibility.
l~1hat is also evident, from the above discussion and with reference particularly to Figures 3 and 4, is that a wide tolerance of bead dimensions and of outer diameter dimensions,

2~ from extremities of the bead 14 of containers 12, may be accommodated, due to the interaction o~ both of the undercuts 44 and 34 against the bead 14. Thus, a tight fit of the lid lU
to the bead 14 of the container 12 is assured, over a relatively wide range of bead sizes and outer diameters.
~ loreover, because it is advantageous to form the lids of the present invention on male molds, it is evident tha~ the 27 discontinuities of the undercuts 34 and 44 make it easier to strip the lids from the moulds on which they are formed.
Figure 5 shows one possible rela~ionship of vertically contiguous lids 10 in a stacking arrangement, where that portion of the lid which deines the cavity 20 oE the bottom lid extends up to and interferes with the underside of the waist portions 32 of the upper lid. Obviously, there may be a possibility that the upper and outer port:ion of the lower lid 10 may also extend up to and interfere with the upper band portion 42 of the upper lid 10. Thus, in that event, the lids 10 would nest very closely one with another, if necessary.' The configuration of the lids is such that, in any event, when the lids are stacked and nest against each other, they do not lock one on another.
However, even in a normal stacking position as lndieated in Figure 5, it is clear that there is a minimal space taken for each lid, because of the rela~ive nesting position in any event of the lids one with respect to the next adjacent lid above it.
Indeed, as an example, lids of a size intended to fit 20 containers having a nominal diameter of 3.75 inches may stack such that one hundred llds occupies 15 inches of height, as opposed to the 19 inches of height taken by ordinary lids of the sort, for example, that are illustrated in the BREWER
patents referred to above. This represents a saving of 20% of storage volume; and when storage and shipping of lids in amounts of hundreds of thousands or millions is considered, 27 such saving is quite significant.
On a lid of the present invention, it is usual that the s~

circumterenti~ tl~ e.lcll of ~l~e outwar(lly extending projections 2~ -- i.e., the widtll across the face of the ~rojections 2~ -- is approximately the same as the circumferential leng~h of the waist portions 32 between them.
Such outwardly extending projections 2~ may be put into place such that the distance between a point on one of them and the respective point on the next adjacent outwardly extending discontinuity (e.g., between the centre lines of each), is 1 degrees.
In general, the cross-section of the cavity, in the portion thereof as i:Llustrated in each of Figures 3 and 4, is transversely arcuate -- i.e., at least the extreme outer portion of the material of the lid lU which defines the cavity 20 forms a segment of an arc. Generally, the position of the upper undercut 44 is such as to be just below and inward of a vertical tan~ent to the mate~rial clefinin~, the cav;ty 2(), at that point.
Obviously, because of the sul~stantially straigh~ sides in the skirt portions 26 of lids 10 according to the present 2~ invention, and the positive engagement of the unclercuts 34 and 44 to the bead 14, there is consicderably less likelihood of interference between adjacent lids as they may be jostle~
against one another when bein~ carried in a bag or other receptacle, so that the likelihood of one of the lids being stripped from its respective container is lessened. Indeecl, it is evident that, if the container is li~ted by radially 27 inwardly directed pressure between the thumb and fingers of the hand, against the slcirt portions 26 or against the outer eclge . ' ' .

~S~3 of the rim portions 40 thereof, additional pressure of the undercuts 34 and 44 against the underside of the bead 14 of the container 12 is created, thereby even more particularly assuring a secure fit of the lid 10 to the container 12. That same pressure may also exist as adjacent lids 10 may rub or jostle against each other.
Also, because ~he bottom of the lower band portion 36 and the vertical wall 38 of the skirt portion 26 of the lid 10 according to this invention is at a wider diameter than that of the cavity 20, it is very easy to fit a lid 10 to a container.
This wider bottom opening of a lid 10 according to this invention, is such ~hat substantially automatic placement of lids 10 on containers may be accommodated, for example in dispensing machines.
Moreover, as mentioned above, the depth of the undercuts 34 provides an accommodation of a variety of bead sizes and bead diameters, for any speclflc nominal size ofcontainer 12.
For example, lids having a diameter such as to accommodate cups having a nominal mouth diameter of 3.75 inches may have 20 undercuts of 0.025 inches at each side as opposed to an undercut of 0.015 of the waist portion of lids such as those referred to in the BREWER patents mentioned above, thereby giving an additional 0.02 inches across the diameter of a cup or container. Thus, a variation of up to about 1% of nominal diameter of the mouth of the container 12, or indeed of the lid 10, may be accommodated. This is all the more important when 27 it is recognized that shrinkage of polystyrene film material of the sort from which lids according to the present invention are ~ ;0~3 normally manufactured may be up to 0.004 inches per inch of diameter of the lid, but variations of shrinkage are such ~hat they may not be posi~ively forecast and designed for in the manufac~ure of each die from which lids according to the present invention may be made. This is especially true when it is considered that the thickness of the polystyrene material, which is extruded, may vary from time to time and from machine to machine.
There has been described a lid for containers, which may 10 be used with food tubs or cups for hot or cold beverages, for example, and which may normally be ormed of thin, flexible plastic material such as polystyrene, using a vacuum thermoforming process over male moulds. Certain specific features of the lids according to the present invention have been described and their advantagès explained. Other variations, and specific design considerations particularly as to the central panel portion, and as to the conformation of the wall portlon 38 and rim 40 which may be eliminated, may be provided for, without departing from the spirit and scope of 20 the appended claimsO

~.

Claims

WHAT IS CLAIMED IS:

1. A lid for containers, made of thin, flexible plastic, for mounting on and receiving the bead of a container, comprising:
a central panel;
a cavity extending around the periphery of the lid and opening downwardly and inwardly to receive the bead of a container to which said lid is fitted;
means connecting said cavity to said central panel;
a skirt portion extending downwardly from said cavity;
said skirt portion having a plurality of outwardly extending projections each having a substantially vertical face with substantially vertical side edges, and substantially vertical side walls extending inwardly from said face;
the portions of said skirt that are between said outwardly extending projections extending inwardly to a waist portion having a plurality of interruptions, one at each projection, and forming an undercut defining said cavity in said waist portion;
said outwardly extending projections and said waist portion all terminating in their lower extremities at a downwardly and outwardly sloped lower band portion;
and said outwardly extending projections terminating in their upper extremities at a respective upper, band portion extending inwardly and upwardly from the upper edge of each said respective vertical face and terminating at said cavity in an upper undercut which is higher and less inwardly extending than the undercut of said waist portion, and which defines the peripheral cavity over said outwardly extending projections.

2. The lid of claim 1, where said lower band portion terminates at a substantially, vertical downwardly extending wall portion.

3. The lid of claim 2, where said substantially vertical, downwardly extending wall portion terminates at an outwardly extending lip.

4. The lid of claim 1, 2 or 3, where said outwardly extending projections all have approximately the same length along the periphery of said lid as the length of said waist portions between them.

5. The lid of claim 1, 2 or 3, where said lid is substantially circular, to be fitted to the bead of a circular beverage cup.

6. The lid of claim 1, 2 or 3, where said lid is substantially circular, to be fitted to the bead of a circular beverage cup; and where the inner surface of said cavity is transversely arcuate.

7. The lid of claim 1, 2 or 3, where said lid is substantially circular, to be fitted to the bead of a circular beverage cup, and the inner surface of said cavity is transversely arcuate; and where each said upper undercut is at a point just below a vertical tangent to said cavity.

8. The lid of claim 1, 2 or 3, where the material of said lid is polystyrene.