PLASTIC FOOD CONTAINER
United States Patent 3620403
A thin-walled thermoplastic container which includes identical dish and cover portions, each having a peripherally extending flange for supporting the other when one is placed on the other to form the assembled container. A restraining collar extending from the flange in the direction of the sidewall prevents crosswise displacement in one direction of one portion with respect to the other, while stabilizing posts in the sidewalls prevent such displacement in the opposite direction. Each portion has locking means which coact with the flange of the other and self engage when one portion is forced against the other.
US Patent References:
Package with interlocking keys
Pease - August 1961 - 2995269
Plastic box container
Ringlen - June 1967 - 3326408
UNITARY FOAM SHEET CONTAINER
Andrews - May 1970 - 3511433
Package with interlocking keys
Pease - August 1961 - 2995269
Plastic box container
Ringlen - June 1967 - 3326408
UNITARY FOAM SHEET CONTAINER
Andrews - May 1970 - 3511433
Application Number:
04/877957
Publication Date:
11/16/1971
Filing Date:
11/19/1969
View Patent Images:
Export Citation:
Primary Class:
Other Classes:
229/406, 426/128, 47/69, 206/551
International Classes:
B65D43/02; B65D11/10; B65D43/10
Field of Search:
220/4,4E,60R 150/0.5 229/22,2.5
Primary Examiner:
George, Lowrance E.
Attorney, Agent or Firm:
James, Logomasini Michael Murphy Neal Willis C. J. E.
Claims:
1. A two-piece, thin-walled container made of plastic material capable of being thermoformed, said container comprising identical dish and cover portions, said dish and cover portions are triangular in peripheral contour, each of said dish and cover portions having an end wall which is integrally joined at its marginal edge to one end of a sidewall which gradually tapers outwardly away from the end wall, a supporting flange portion extending laterally outwardly at the other end of each sidewall, a restraining collar extending from the outer extremity of the flange portion in the same general direction as the sidewall, a plurality of inwardly directed stabilizing posts spaced from each other and formed along one side of said triangular contour of said cover and dish portions, said stabilizing posts having end sections extending vertically beyond the flange portion, locking means in the restraining collar of each identical dish and cover portion for holding the cover portion vertically in place on the dish portion, said restraining collar extending only one-half way around the periphery including the peripheral sections of the dish and cover portions in which the stabilizing posts are located, whereby said end sections of the stabilizing posts abut against upper sections of the sidewalls on sliding one of said cover and dish portions transversely in one direction with respect to the other and said restraining collar abuts against said flange portion on sliding one of said cover and dish portions transversely in the opposite direction with respect to the other when said cover portion is mounted on said dish portion such that the flange of the cover portion is supported on the flange of the dish portion with the end walls of each on opposite sides of said flanges.
2. The container of claim 1 wherein the plastic material is transparent, oriented polystyrene.
3. The container of claim 1 wherein each end of the restraining collar at its joint with the supporting flange portion tapers gradually into said flange portion along a section of the periphery of the container.
2. The container of claim 1 wherein the plastic material is transparent, oriented polystyrene.
3. The container of claim 1 wherein each end of the restraining collar at its joint with the supporting flange portion tapers gradually into said flange portion along a section of the periphery of the container.
Description:
This invention relates to containers and more particularly to thermoplastic containers of the single use, throwaway variety.
Disposable thermoplastic containers of many different varieties have been introduced in the marketplace in recent years for holding consumable solid and liquid products. Thus, open topped cups for beverages dispensable from vending machines have been supplied. Film overwrapped trays for meat, fruit, produce, etc. are likewise known. Tubs tightly capped with removable lids for holding cottage cheese, margarine, butter, etc. in hermetic confinement also have been well developed in the art.
Thus far, however, the only known food items dispensable from vending machines for consumption as a light lunch, snack, or dessert are relatively sturdy items such as sandwiches, fruit, etc. which are film overwrapped and are of such a consistency such that they will not disintegrate or undesirably adhere to the fingers of the purchaser on removing the protective covering. Accordingly, though a market for such products would appear to exist, food items such as pies, cakes with or without frosting, filled pastries, etc. which are susceptible to disintegration during handling and are therefore ordinarily consumed with an eating utensil, have heretofore not appeared in vending machines because of the lack of a suitable inexpensive yet sturdy, disposable container for holding such items, both prior to dispensing and during consumption by the purchaser.
Now there has been developed a unique container to fulfill this long felt need.
Accordingly, it is a principal object of this invention to provide a structurally stable, single-use, self-supporting, two-piece, covered container for holding an appropriate product.
An additional object of this invention is to provide a container of the aforementioned variety adapted for use in vending machines for holding single servings of relatively easily disintegratable food items.
Another object of this invention is to provide a container of the aforementioned variety which may be used as a dish out of which the purchased item may be consumed.
A further object of this invention is to provide an economical container of the aforementioned variety which may be readily formed by conventional thermoforming techniques.
An additional object of this invention is to provide a container of the aforementioned variety which is easy to manufacture, convenient to inventory, assemble and fill with an appropriate product and which is very desirable for use by the consumer.
Other objects of this invention will in part be obvious and will in part appear hereinafter.
These and other objects are accomplished by providing a two-piece, thin-walled container, preferably for holding food items, made of a plastic material capable of being thermoformed, the container comprising identical dish and cover portions, each of the dish and cover portions having an end wall which is integrally joined at its marginal edge to one end of a sidewall which gradually tapers outwardly away from the end wall, a supporting flange portion extending laterally outwardly at the other end of each sidewall, a restraining collar extending in the same general direction as the sidewall from the outer extremity of the flange portion, a plurality of inwardly directed stabilizing posts spaced from each other and formed in the sidewalls of the cover and dish portions, the stabilizing posts having end sections extending vertically beyond the flange portion, locking means in the restraining collar of each identical dish and cover portion to hold the cover portion vertically in place on the dish portion, whereby the end sections of the stabilizing posts abut against upper sections of the sidewalls on sliding one of the cover and dish portions transversely in one direction with respect to the other and the restraining collar abuts against the flange portion on sliding one of the cover and dish portions transversely in the opposite direction with respect to the other when the cover portion is mounted on the dish portion such that the flange of the cover portion is supported on the flange of the dish portion with the end walls of each on opposite sides of the flanges.
In describing the overall invention, reference will be made to the accompanying drawing in which:
FIG. 1 is a perspective view of one form of the container of the invention in open position;
FIG. 2 is a plan view of the upper half of the container of FIG. 1;
FIG. 3 is an elevational view of the container portion of FIG. 2;
FIG. 4 is an enlarged sectional view taken at 4--4 of FIG. 1 with the container in closed position; and
FIG. 5 is a view similar to FIG. 4 taken at 5--5 of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
With reference to the drawings, wherein identical numerals refer to identical parts, there is shown in FIG. 1, a two-piece, transparent, thin-walled food container made of a plastic material capable of being thermoformed, and which is generally indicated as 10.
In the illustrated embodiment, the overall shape of the container is triangular since this configuration is particularly adapted to accommodate sliced products such as pies, cakes and the like. Obviously alternative contours such as circular, square, rectangular and other multisided configurations could be used, as long as the shape is symmetrical about either side of an imaginary vertical plane passing through the center of the container.
Container 10 comprises dish and cover portions 12, each of which is exactly identical in construction. Each of dish and cover portions 12 has an end wall 14 which is integrally joined at its marginal edge to one end of continuous sidewall 16, which, with respect to the lower half portion in FIG. 1, tapers angularly upwardly and outwardly from end wall 14, and, with respect to the upper portion, tapers angularly downwardly and outwardly from end wall 14. Sidewalls 16 of both cover and dish portions 12 taper outwardly to permit stacking a plurality of the container halves within each other prior to filling so as to optimize storage space. Each portion 12 further comprises a planar-oriented supporting flange portion 18 extending outwardly in a direction parallel or approximately parallel to that of end wall 14 around the periphery of each portion 12 at the other end of sidewall 16. End wall 14 and sidewall 16 define a chamber in the lower half portion 12 of container 10 for holding an appropriate product. Each portion 12 is preferably peripherally continuous along the full extent of sidewall 16 and end wall 14, being free of any interruptions, ledges, crevices, inaccessible corners etc. which could serve as areas of the package within which the contents could become lodged. This is especially desirable when the container is to hold a food product. Each portion 12 further has a restraining collar 20 extending in the same general direction as sidewall 16 and substantially perpendicular to flange portion 18 at its outer extremity (FIG. 4). Typically, collar 20 may vary about 15 ° either way from being perpendicular to flange portion 18.
As an important phase of the present invention, there is provided in each half 12 of container 10, a plurality of inwardly directed, stabilizing posts 22 spaced from each other and formed in sidewall 16 of each container half 12. Stabilizing posts 22 have end sections 24 (FIG. 4) which extend vertically beyond flange portion 18 and which terminate short of the outer extremity 26 of restraining collar 20 of the particular container half in which they are situated. In the preferred triangular embodiment of the drawings, sidewalls 16 comprise sections of the cover and dish portions which are angularly related to each other so as to form corners 28, 30 and 32. Stabilizing posts 22 in such a configuration are positioned intermediate two of the corner areas, for example along side 34 (FIG. 2) of the container.
Restraining collar 20 of each identical dish and cover portion 12 has locking means 36 (FIG. 5) formed therein adapted to resiliently snap around flange portion 18 of the other half portion to hold the cover portion vertically in place on the dish portion. In the embodiment of the drawings, locking means 36 comprises a pair of inwardly curving U-shaped detents 38 in the same side 34 of the container as are situated stabilizing posts 22. Detents 38, however, are adjacent to but not in horizontal alignment with posts 22, since an aligned configuration presents difficulties in thermoforming because of the problem of extricating the section of flange portion 18 intermediate such an aligned post and detent configuration from the forming mold. This difficulty is caused by the reverse taper of post 22 with respect to sidewall 16 and of detents 38 with respect to collar 20.
As is apparent from FIG. 1, when container 10 is in closed position, the cover portion is mounted on the dish portion such that the flange 18 of the cover portion is supported on the flange of the dish portion with the endwalls 14 of each on opposite sides of flanges 18. In such a position, collar 20 of the lower dish portion extends upwardly so as to surround the outer end of flange 18 of the upper portion (FIG. 1), while the corresponding collar 20 of the upper cover portion extends downwardly so as to surround the outer edge of flange portion 18 of the lower portion (FIG. 4). Also, when container 10 is in closed position, end sections 24 of stabilizing posts 22 along one side of the upper portion of the container below flange 18 project into the chamber formed by lower dish portion 12 (FIG. 4) whereas the reverse is true with respect to the lower portion of the container, i.e. the upper ends of posts 22 protrude upwardly into the chamber formed by the cover portion of the container. Thus with respect to the configuration of FIG. 1, if the cover portion should be moved in a planar direction to the right or, conversely, the dish portion moved to the left, for example during jostling while being closed after filling and/or inserted into a vending machine, end portions 24 of stabilizing posts 22 will abut against upper section 35 of sidewall 16 of dish portion 12. This prevents the thin-walled container from distorting out of shape and maintains cover portion 14 in substantial vertical alignment on lower dish portion 12. If the reverse movement should occur, i.e. the cover portion move to the left in FIG. 1 or the base portion move to the right, restraining collar 20 of the lower portion will abut against the outer edge of flange 18 of the upper portion and thereby prevent any further distortional movement of the container.
The extent 24 to which each stabilizing post 22 projects into the chamber formed by the opposite portion when the container is in closed position is greater than the vertical distance 37 (FIG. 5) between flange 18 and the upper end of the particular leg 40 of the U-shaped detent 38 of locking means 36 which is closest to its flange portion 18. Thus, if the cover portion should accidentally be incrementally moved upwardly or the lower portion downwardly a distance indicated as 37 in FIG. 5 during handling, the lower end 24 of each stabilizing post 22 will still be beyond the flange portion 18 of the opposite portion, and can therefore still perform its container-stabilizing function. However, end portion 24 of each stabilizing post 22 should not project excessively into the chamber of dish portion 12, since this decreases the open volume available for confining the container contents. Preferably the extent to which each stabilizing post 22 protrudes into the chamber of the other portion when the container is in closed position in order to accomplish its desired function under all circumstances is between one-sixteenth to one-fourth inch. In any event, lower end portions 24 should not extend beyond the extremity 26 of collar 20 in order to permit forming the container by conventional thermoforming techniques.
In the preferred form of the present invention, the container is designed to be made by means of a trapped sheet, cut-in-place thermoforming system. Thus, each restraining collar of the dish and cover portions tapers gradually into flange portions 18 along a section of the periphery of the container, as indicated at 42. It should be understood, however, that alternatively collar 20 could be squared off at its joint with flange portion 18 and need not be of a sloping configuration when formed in a post trim thermoforming system. Likewise, though it is preferred for purposes of container stability that collar 20 extend around only one-half of the periphery of each portion as shown in the drawings, it should be recognized that satisfactory results are attainable when collar 20 extends entirely around the periphery of each half portion of the container. In the latter instance, however, the half portion without the locking means must be shorter in the vertical direction than that having the locking means. In other words, with respect to the preferred embodiment, the half portion without the locking means may have a short restraining collar portion which extends in the vertical direction no greater than the distance between flange 18 and the upper end of the leg of the U-shaped detent adjacent flange 18 of the collar portion having locking means 36 therein.
The above description and particularly the drawings are set forth for purposes of illustration only and are not to be taken in a limited sense.
The identical dish and cover portions of the novel container of the present invention are relatively shallow, having a depth of between 0.5 to 3 inches. Thus, when the contents of the container is a food product, this permits easy access thereto with an eating utensil.
The flange of the dish and cover portions of the container must be sufficiently wide to provide adequate support for the other half when the container is in its assembled position, yet, in the case of a container for use in a vending machine, the flange cannot be so wide as to interfere with the relatively compact compartment within which the container is to be confined after filling. Generally, a width of between one thirty-second to three-eighths inch for these portions of the container accomplishes the desired objectives.
The sealing means of the container of the present invention preferably function outside of the recesses formed in the cover and dish portions in order to avoid contact with the contents thereof, and to permit holding the internal container volume at a minumum in order to economically yet effectively confine the contents. In other words, the locking means of the container coact with the flange portions which project outwardly of the interior of the cover and dish portions. By designing the locking means to be self-locking, time to assemble and open the filled package may be kept at a minimum, with no auxiliary means, such as adhesives, sealants, auxiliary clips etc. being necessary, these serving to increase the cost of the container and often being difficult to disengage with out disrupting the contents.
The stabilizing posts of the container of the invention occupy a limited area of the container periphery and may vary in number depending on the size of the container, at least two, however being considered necessary. For most container sizes, between two and six posts in each container half provide acceptable results.
The material from which the container is made is a synthetic resin sheet capable of being thermoformed, and particularly a sheet of a material which may be biaxially oriented to impart strength thereto at a relatively low cost per pound. A particularly preferred thermoplastic is biaxially oriented polystyrene, which in the case of a container for vending machine applications, is transparent for purposes of displaying the contents. The sheet should be relatively thin before drawing, in order to be consistent with the intended single-use, disposable, low-cost, variety of container. Thicknesses between 5 to 40 mils provide satisfactory results in terms of container performance. At sheet thicknesses below 5 mils, the formed container generally does not have sufficient strength to be self-supporting in a sufficiently sturdy manner in a vending machine dispensing operation. On the other hand, sheet thicknesses in excess of 40 mils are relatively uneconomical and are rather difficult to draw while still retaining the strength imparting biaxial orientation in the thermoplastic.
"Transparent" as used herein is meant to indicate that the nature of the contents can be determined by viewing the exterior of the container. This term therefore characterizes a container which permits partial as well as complete visibility of the contents.
It will be understood that many variations and modifications of the embodiments herein described will be obvious to those skilled in the art, and may be carried out without departing from the spirit and scope of the invention as hereinafter claimed.
Disposable thermoplastic containers of many different varieties have been introduced in the marketplace in recent years for holding consumable solid and liquid products. Thus, open topped cups for beverages dispensable from vending machines have been supplied. Film overwrapped trays for meat, fruit, produce, etc. are likewise known. Tubs tightly capped with removable lids for holding cottage cheese, margarine, butter, etc. in hermetic confinement also have been well developed in the art.
Thus far, however, the only known food items dispensable from vending machines for consumption as a light lunch, snack, or dessert are relatively sturdy items such as sandwiches, fruit, etc. which are film overwrapped and are of such a consistency such that they will not disintegrate or undesirably adhere to the fingers of the purchaser on removing the protective covering. Accordingly, though a market for such products would appear to exist, food items such as pies, cakes with or without frosting, filled pastries, etc. which are susceptible to disintegration during handling and are therefore ordinarily consumed with an eating utensil, have heretofore not appeared in vending machines because of the lack of a suitable inexpensive yet sturdy, disposable container for holding such items, both prior to dispensing and during consumption by the purchaser.
Now there has been developed a unique container to fulfill this long felt need.
Accordingly, it is a principal object of this invention to provide a structurally stable, single-use, self-supporting, two-piece, covered container for holding an appropriate product.
An additional object of this invention is to provide a container of the aforementioned variety adapted for use in vending machines for holding single servings of relatively easily disintegratable food items.
Another object of this invention is to provide a container of the aforementioned variety which may be used as a dish out of which the purchased item may be consumed.
A further object of this invention is to provide an economical container of the aforementioned variety which may be readily formed by conventional thermoforming techniques.
An additional object of this invention is to provide a container of the aforementioned variety which is easy to manufacture, convenient to inventory, assemble and fill with an appropriate product and which is very desirable for use by the consumer.
Other objects of this invention will in part be obvious and will in part appear hereinafter.
These and other objects are accomplished by providing a two-piece, thin-walled container, preferably for holding food items, made of a plastic material capable of being thermoformed, the container comprising identical dish and cover portions, each of the dish and cover portions having an end wall which is integrally joined at its marginal edge to one end of a sidewall which gradually tapers outwardly away from the end wall, a supporting flange portion extending laterally outwardly at the other end of each sidewall, a restraining collar extending in the same general direction as the sidewall from the outer extremity of the flange portion, a plurality of inwardly directed stabilizing posts spaced from each other and formed in the sidewalls of the cover and dish portions, the stabilizing posts having end sections extending vertically beyond the flange portion, locking means in the restraining collar of each identical dish and cover portion to hold the cover portion vertically in place on the dish portion, whereby the end sections of the stabilizing posts abut against upper sections of the sidewalls on sliding one of the cover and dish portions transversely in one direction with respect to the other and the restraining collar abuts against the flange portion on sliding one of the cover and dish portions transversely in the opposite direction with respect to the other when the cover portion is mounted on the dish portion such that the flange of the cover portion is supported on the flange of the dish portion with the end walls of each on opposite sides of the flanges.
In describing the overall invention, reference will be made to the accompanying drawing in which:
FIG. 1 is a perspective view of one form of the container of the invention in open position;
FIG. 2 is a plan view of the upper half of the container of FIG. 1;
FIG. 3 is an elevational view of the container portion of FIG. 2;
FIG. 4 is an enlarged sectional view taken at 4--4 of FIG. 1 with the container in closed position; and
FIG. 5 is a view similar to FIG. 4 taken at 5--5 of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
With reference to the drawings, wherein identical numerals refer to identical parts, there is shown in FIG. 1, a two-piece, transparent, thin-walled food container made of a plastic material capable of being thermoformed, and which is generally indicated as 10.
In the illustrated embodiment, the overall shape of the container is triangular since this configuration is particularly adapted to accommodate sliced products such as pies, cakes and the like. Obviously alternative contours such as circular, square, rectangular and other multisided configurations could be used, as long as the shape is symmetrical about either side of an imaginary vertical plane passing through the center of the container.
Container 10 comprises dish and cover portions 12, each of which is exactly identical in construction. Each of dish and cover portions 12 has an end wall 14 which is integrally joined at its marginal edge to one end of continuous sidewall 16, which, with respect to the lower half portion in FIG. 1, tapers angularly upwardly and outwardly from end wall 14, and, with respect to the upper portion, tapers angularly downwardly and outwardly from end wall 14. Sidewalls 16 of both cover and dish portions 12 taper outwardly to permit stacking a plurality of the container halves within each other prior to filling so as to optimize storage space. Each portion 12 further comprises a planar-oriented supporting flange portion 18 extending outwardly in a direction parallel or approximately parallel to that of end wall 14 around the periphery of each portion 12 at the other end of sidewall 16. End wall 14 and sidewall 16 define a chamber in the lower half portion 12 of container 10 for holding an appropriate product. Each portion 12 is preferably peripherally continuous along the full extent of sidewall 16 and end wall 14, being free of any interruptions, ledges, crevices, inaccessible corners etc. which could serve as areas of the package within which the contents could become lodged. This is especially desirable when the container is to hold a food product. Each portion 12 further has a restraining collar 20 extending in the same general direction as sidewall 16 and substantially perpendicular to flange portion 18 at its outer extremity (FIG. 4). Typically, collar 20 may vary about 15 ° either way from being perpendicular to flange portion 18.
As an important phase of the present invention, there is provided in each half 12 of container 10, a plurality of inwardly directed, stabilizing posts 22 spaced from each other and formed in sidewall 16 of each container half 12. Stabilizing posts 22 have end sections 24 (FIG. 4) which extend vertically beyond flange portion 18 and which terminate short of the outer extremity 26 of restraining collar 20 of the particular container half in which they are situated. In the preferred triangular embodiment of the drawings, sidewalls 16 comprise sections of the cover and dish portions which are angularly related to each other so as to form corners 28, 30 and 32. Stabilizing posts 22 in such a configuration are positioned intermediate two of the corner areas, for example along side 34 (FIG. 2) of the container.
Restraining collar 20 of each identical dish and cover portion 12 has locking means 36 (FIG. 5) formed therein adapted to resiliently snap around flange portion 18 of the other half portion to hold the cover portion vertically in place on the dish portion. In the embodiment of the drawings, locking means 36 comprises a pair of inwardly curving U-shaped detents 38 in the same side 34 of the container as are situated stabilizing posts 22. Detents 38, however, are adjacent to but not in horizontal alignment with posts 22, since an aligned configuration presents difficulties in thermoforming because of the problem of extricating the section of flange portion 18 intermediate such an aligned post and detent configuration from the forming mold. This difficulty is caused by the reverse taper of post 22 with respect to sidewall 16 and of detents 38 with respect to collar 20.
As is apparent from FIG. 1, when container 10 is in closed position, the cover portion is mounted on the dish portion such that the flange 18 of the cover portion is supported on the flange of the dish portion with the endwalls 14 of each on opposite sides of flanges 18. In such a position, collar 20 of the lower dish portion extends upwardly so as to surround the outer end of flange 18 of the upper portion (FIG. 1), while the corresponding collar 20 of the upper cover portion extends downwardly so as to surround the outer edge of flange portion 18 of the lower portion (FIG. 4). Also, when container 10 is in closed position, end sections 24 of stabilizing posts 22 along one side of the upper portion of the container below flange 18 project into the chamber formed by lower dish portion 12 (FIG. 4) whereas the reverse is true with respect to the lower portion of the container, i.e. the upper ends of posts 22 protrude upwardly into the chamber formed by the cover portion of the container. Thus with respect to the configuration of FIG. 1, if the cover portion should be moved in a planar direction to the right or, conversely, the dish portion moved to the left, for example during jostling while being closed after filling and/or inserted into a vending machine, end portions 24 of stabilizing posts 22 will abut against upper section 35 of sidewall 16 of dish portion 12. This prevents the thin-walled container from distorting out of shape and maintains cover portion 14 in substantial vertical alignment on lower dish portion 12. If the reverse movement should occur, i.e. the cover portion move to the left in FIG. 1 or the base portion move to the right, restraining collar 20 of the lower portion will abut against the outer edge of flange 18 of the upper portion and thereby prevent any further distortional movement of the container.
The extent 24 to which each stabilizing post 22 projects into the chamber formed by the opposite portion when the container is in closed position is greater than the vertical distance 37 (FIG. 5) between flange 18 and the upper end of the particular leg 40 of the U-shaped detent 38 of locking means 36 which is closest to its flange portion 18. Thus, if the cover portion should accidentally be incrementally moved upwardly or the lower portion downwardly a distance indicated as 37 in FIG. 5 during handling, the lower end 24 of each stabilizing post 22 will still be beyond the flange portion 18 of the opposite portion, and can therefore still perform its container-stabilizing function. However, end portion 24 of each stabilizing post 22 should not project excessively into the chamber of dish portion 12, since this decreases the open volume available for confining the container contents. Preferably the extent to which each stabilizing post 22 protrudes into the chamber of the other portion when the container is in closed position in order to accomplish its desired function under all circumstances is between one-sixteenth to one-fourth inch. In any event, lower end portions 24 should not extend beyond the extremity 26 of collar 20 in order to permit forming the container by conventional thermoforming techniques.
In the preferred form of the present invention, the container is designed to be made by means of a trapped sheet, cut-in-place thermoforming system. Thus, each restraining collar of the dish and cover portions tapers gradually into flange portions 18 along a section of the periphery of the container, as indicated at 42. It should be understood, however, that alternatively collar 20 could be squared off at its joint with flange portion 18 and need not be of a sloping configuration when formed in a post trim thermoforming system. Likewise, though it is preferred for purposes of container stability that collar 20 extend around only one-half of the periphery of each portion as shown in the drawings, it should be recognized that satisfactory results are attainable when collar 20 extends entirely around the periphery of each half portion of the container. In the latter instance, however, the half portion without the locking means must be shorter in the vertical direction than that having the locking means. In other words, with respect to the preferred embodiment, the half portion without the locking means may have a short restraining collar portion which extends in the vertical direction no greater than the distance between flange 18 and the upper end of the leg of the U-shaped detent adjacent flange 18 of the collar portion having locking means 36 therein.
The above description and particularly the drawings are set forth for purposes of illustration only and are not to be taken in a limited sense.
The identical dish and cover portions of the novel container of the present invention are relatively shallow, having a depth of between 0.5 to 3 inches. Thus, when the contents of the container is a food product, this permits easy access thereto with an eating utensil.
The flange of the dish and cover portions of the container must be sufficiently wide to provide adequate support for the other half when the container is in its assembled position, yet, in the case of a container for use in a vending machine, the flange cannot be so wide as to interfere with the relatively compact compartment within which the container is to be confined after filling. Generally, a width of between one thirty-second to three-eighths inch for these portions of the container accomplishes the desired objectives.
The sealing means of the container of the present invention preferably function outside of the recesses formed in the cover and dish portions in order to avoid contact with the contents thereof, and to permit holding the internal container volume at a minumum in order to economically yet effectively confine the contents. In other words, the locking means of the container coact with the flange portions which project outwardly of the interior of the cover and dish portions. By designing the locking means to be self-locking, time to assemble and open the filled package may be kept at a minimum, with no auxiliary means, such as adhesives, sealants, auxiliary clips etc. being necessary, these serving to increase the cost of the container and often being difficult to disengage with out disrupting the contents.
The stabilizing posts of the container of the invention occupy a limited area of the container periphery and may vary in number depending on the size of the container, at least two, however being considered necessary. For most container sizes, between two and six posts in each container half provide acceptable results.
The material from which the container is made is a synthetic resin sheet capable of being thermoformed, and particularly a sheet of a material which may be biaxially oriented to impart strength thereto at a relatively low cost per pound. A particularly preferred thermoplastic is biaxially oriented polystyrene, which in the case of a container for vending machine applications, is transparent for purposes of displaying the contents. The sheet should be relatively thin before drawing, in order to be consistent with the intended single-use, disposable, low-cost, variety of container. Thicknesses between 5 to 40 mils provide satisfactory results in terms of container performance. At sheet thicknesses below 5 mils, the formed container generally does not have sufficient strength to be self-supporting in a sufficiently sturdy manner in a vending machine dispensing operation. On the other hand, sheet thicknesses in excess of 40 mils are relatively uneconomical and are rather difficult to draw while still retaining the strength imparting biaxial orientation in the thermoplastic.
"Transparent" as used herein is meant to indicate that the nature of the contents can be determined by viewing the exterior of the container. This term therefore characterizes a container which permits partial as well as complete visibility of the contents.
It will be understood that many variations and modifications of the embodiments herein described will be obvious to those skilled in the art, and may be carried out without departing from the spirit and scope of the invention as hereinafter claimed.