US3756492A - High strength open bottom packaging tray - Google Patents

Abstract

A tray of molded wood pulp or the like is provided for the packaging of food, such as produce, preferably in conjunction with an overwrapped transparent film. The tray bottom is formed of a plurality of upright U or V shaped ribs joining or intersecting in two directions and defining open windows therebetween, the height of each V shaped rib being on the order of several times the thickness of remainder of the tray, and the total volume of the inverted V shaped ribs being about equal to the volume of a bottom of a solid bottom tray of the same size.

Description

United States Patent 11 1 Reifers et al. Sept. 4, 1973 54] HIGH STRENGTH OPEN BOTTOM 2,918,379 12/1959 Lune 99/174 PACKAGING TRAY 2,922,541 1/1960 Martelli et 21]....

3,056,232 10/1962 Chaplin 229 25 ux [75] Inventors: Richard Reifers, New Canaan, 3,185,371 5 1965 Reifers 229/25 R Conn.; Kenneth D. Bixler, 3,217,962 11/1965 Weiss 229/25 R Huntington, 3,346,400 10 1967 Roesner 22912.5 x 3,357,625 12/1967 Malmgrem. 229 25 Asslgneei Dlammld lntematlonfll Corporation, 3,480,178 11 1969 Morgan 229 215 x N York, NY 3,698,623 10/1972 Bixler 229 2 5 [22] Filed: May 24, 1972 Primary ExaminerDavis T. Moorhead [21] Appl- 2567453 Attorney-Karl W. Flocks Related US. Application Data Continuation-impart of Ser. No. 185,197, Sept. 30, 1971, which is a continuation-in-part of Ser. No. 111,578, Feb. 1, 1971.

[52} U.S. Cl 229/2.5, 206/4533, 217/26, 99/174 [51] Int. Cl 365d 1/00, 365d 65/00 [58] Field of Search 229/2.5, 29 F, 29 M; 217/26, 30; 206/4533; 99/174 [56] References Cited UNITED STATES PATENTS 442,500 12/1890 Weaver 229/42 2,310,465 2/1943 Samford 229/29 F [57] ABSTRACT A tray of molded wood pulp or the like is provided for the packaging of food, such as produce, preferably in conjunction with an overwrapped transparent film. The tray bottom is formed of a plurality of upright U or V shaped ribs joining or intersecting in two directions and defining open windows therebetween, the height of each V shaped rib being on the order of several times the thickness of remainder of the tray, and the total volume of the inverted V shaped ribs being about equal to the volume of a bottom of a solid bottom tray of the same size.

8 Claims, 14 Drawing Figures PATENTEB SEP 4 8813 sum 3 or 4 FIG PATENTEBSEP 4am 3'756'492 sum u or 4 1 HIGH STRENGTH OPEN BOTTOM PACKAGING TRAY This is a continuation-in-part of application Ser. No. 185,197 filed Sept. 30, 1971 which is in turn a continuation-in-part of application Ser. No. 111,578 filed Feb. 1, 1971.

FIELD OF INVENTION The present invention relates to an open bottom food conatiner and, more particularly, to a food container primarily for use for the packaging of produce, and overwrapped with a transparent film, and where the bottom wall is replaced with a plurality of open windows defined by structural beams.

BACKGROUND Molded wood pulp food trays have served the food packaging industry well for many years for the packaging of food commodities. Such trays have the advantage, besides low price and cost to the consumer, of being clean, sturdy and safe; of being biodegradable so as to minimize the solids pollution problem; of being capable of assimilating the liquid juices which exude from some food products; of being soft and relatively flexible so as to protect and prevent bruising of food products such as fresh fruit and tomatoes; and of being air and vapor permeable to maintain freshness and permit passage of liquid vapor. Nevertheless, in spite of the many advantages of such molded wood pulp trays, certain locals have effectively outlawed their usage by the requirement that a very high percentage of certain types of food packaged therein be visible to the consumer, and since such molded wood pulp trays are normally opaque, they have not met this legal requirement.

Consequently, in such locals, the only packaging trays utilizable in view of such laws are clear plastic trays. These clear plastic trays have many defects, some shared with foam plastic trays, including reduced strength, increased cost, fabrication of nonbiodegradable material. These plastic trays collect in puddles any liquids which might be present, thereby not only causing possible discoloration and rotting of the packaged product, but also serving as a bacterial breeding ground and further serving to opacify the package itself and provide distortion in the remaining transparent areas, thereby contributing to the very problem which such trays were designed to overcome. In addition, such trays being formed of non-breathable material, inhibit oxygen transfer to the food products and moisture vapor transmission from the food product, thereby in many cases reducing freshness.

Such prior plastic trays have sharp edges which tend to cut the packaging film and/or hands, as well as the product packaged therein. Where meat or poultry is packaged there is often the exudation of bloody liquid which collects in puddles; besides providing a bacterial oxide and water vapor requires a high vapor transmission rate in packaging, to maintain product freshness.

Another defect of the clear plastic trays involves their transmission of light lengthwise through the tray walls to provide a light pipe or fiber optic effect which increases discoloration of some food products, such as hamburger and other meats. The light has a negative effect on meat quality causing discoloration more quickly than meat which is maintained more in the dark but under otherwise similar conditions. Because of the light pipe effect, hamburger and other meat packaged in clear plastic has its botom exposed to light constantly even when the tray rests on an opaque object such as the bottom of the meat cooler or an underlying package or between two packages.

Food packaging trays have evolved substantially over the years. The earlier trays had essentially straight side walls and a flat peripheral lip, and these served the trade successfully for many years, particularly for the packaging of meat. In more recent years, these earlier trays have been used for the packaging of produce, such as a half dozen deluxe apples or oranges, provided with a transparent film overwrap. However, as the nature of transparent plastic wrap film changed and nonelastic cellophane was replaced with the more elastic thermoplastic overwrap films, the tray in accordance with Reifers US. Pat. No. 3,185,371 was developed, and this tray became the leader in the field. In more recent years there has been an increasing desire for greater visibility of the food packaged.

One of the earlier attempts to provide visibility through the bottom wall of the tray involved simply providing one or more relatively large openings in the bottom of the tray. However, this was found to weaken the tray and was not a successful approach to the problem. The next attempt was to utilize a raised lip about the periphery of the opening(s) in the bottom wall of the tray, the function, in the packaging of meat, of the upwardly extending lip being to hold the meat upwardly, to trap juices and to stiffen and reinforce the sturcture. However, this approach was also not successful as the structure was still too weak and, in the packaging of meat, the meat tended to sag through the large opening(s).

SUMMARY It is, accordingly, an object of the present invention to overcome the defects of the prior art.

breeding ground, such bloody liquid goes under the tray and acts to release the sealed film causing soiled hands, soiled check-out counters, leaking packages, etc. The non-breathing nature of these plastic trays causes discoloration of the meat, including hamburger, at the bottom of the tray, due to the lack of oxygen migration through the tray, it being well known that meat in plastic trays deteriorates on the bottom first. The non-breathable nature of these plastic trays makes them critically undesirable for the packaging of produce. Oxygen assimilation and the release of carbon di- It is another object of" the present invention to provide a molded, nestable tray, preferably of wood pulp or the like, primarily for the packaging of soft produce or the like and which, in spite of being made of generally opaque or translucent material, provides a relatively high degree of visibility of the packaged product. It is another object of the present invention to provide for the clean, safe and effective packaging of food products.

It is another object of the present invention to provide a food tray which, although being primarily open on the bottom is sufficiently strong to be handled under all conditions.

It is another object of the present invention to provide a food packaging tray which is not only effective but which is inexpensive.

It is another object of the present invention to provide a food packaging tray which may provide from a minimum of 55 percent total visibility (entire surface of food packaged) up to about 85 percent on certain round fruits, and which also tends to softly support the food without bruising or other damage thereto.

It is another object of the present invention to provide a high visibility food tray having an open bottom which has increased, rather than decreased, strength even when overwrapped with stretchable, transparent plastic film which acts to compress and sometimes collapse a conventional tray; and which also has high beam strength.

These and other objects and the nature and advantages of the instant invention will be more apparent from the following description:

In our parent application, Ser. No. 111,578, we described a tray primarily intended for the packaging of meat and similar products, which tray had a bottom of inverted U or V cross-section shaped ribs extending thereacross. It was stated in such parent application that the V ribs may be upright rather than inverted. Parent application Ser. No. 1 1 1,578 is an improvement over the construction shown in the earlier Bixler application Ser. No. 53,545 which uses a plurality of intersecting inverted V shaped ribs. The Bixler construction provides maximum visibility with a relatively strong construction and is, in many respects, a successful approach to the problem, although under certain conditions there has been found to be a need to provide increased strengthening of the Bixler construction, particularly in the area where the V ribs meet the side walls of the tray where fault lines" may exist.

The present invention provides such an improved structure in a food packaging tray primarily intended for the packaging of produce, although it may be used for packaging of other food products such as meat, particularly hamburger. The construction of the present invention utilizes high and strong ribs on the nature of the ribs in parent application Ser. No. 111,578, but they are upright rather than being inverted. It is found in accordance with the present invention that in order to provide the maximum strength desirable in all packaging situations, the upright V or V shaped ribs should be of substantial height to provide a thick platform or pallet upon which the food product is supported, and wherein the total volume of the ribs forming the platform is about equal to the volume of a bottom of a conventional tray of the same size, such as that shown in the Reifers U.S. Pat. No. 3,185,371.

Certain food products, such as meat, have increased shelf life as the oxygenation to the food product is improved. By providing more open space, the construction according to the present invention not only improves visibility of the product, but improves oxygen transmission to the food product packaged therein in conjunction with a plastic overwrap film. In addition, the raised ribs provide an immediately available supply of trapped oxygen to the package.

By use of the upright V shaped ribs, there is utilized a different type of transition zone between the side walls of the tray and such ribs of upright V crosssection. This transition zone is such that no fault lines or notches are provided in the side or end wall and the transition zone, and this may be accomplished by providing a rounded transition zone from the end and side walls, which in turn merges into a peripheral gutter, such peripheral gutter forming the furthest point to which the upright V ribs extend. It is preferably accomplished by extending the side walls directly into the peripheral rib.

The characteristics of the package provided in accordance with the present invention, some of which are indicated above, are accomplished by the use of relatively high support beams, namely the upright U or V cross-section ribs of about 3/16 inch height or more, which are themselves strong, which are coupled to the side and end walls in a way that maintains high side walls beam strength, for highest total package strength. The transition between the ribs and the inner periphery of the tray being relatively smooth and uninterrupted without notches, the strength provided is high and failure sites are reduced to a minimum. This is in contrast with rib forms which have been previously suggested in trays of uniform material thickness, such as plastic, that have the liability of an interrupted edge which provides a fault site.

When made of molded wood pulp, the construction of the present invention is particularly satisfactory. The upright V ribs may be filled at their upper surface, the extent of filling being determined by the V angle, the type of wood or paper fiber from which the tray is formed, and the weight and rib height. These factors may be selected to optimize window visibility, strength and nesting of the tray. For a tray intended for packaging of produce, the steepest practical V" angle should be selected, to maximize filling to create a soft and relatively flat pallet surface; in practice an included V- angle of 5 to 35 has been shown to be satisfactory.

The fundamental aspects of the tray in accordance with the present invention may be said to be: spaced beam members, the spacing being open between such beam members to allow for viewing the tray contents between each beam of relatively solid material. The section modulus of the beams must be such that in combination with the end and side walls, the total strength equals or exceeds the beam strength of a tray of the same material of equal weight with a flat, solid bottom.

For a better understanding of the invention, possible embodiments thereof will now be described with reference to the attached drawings, it being understood that these embodiments are to be intended as merely exemplary and in no way limitative.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of an embodiment of a tray in accordance with the present invention;

FIG. 2 is a bottom plan view of the tray of FIG. 1;

FIG. 3 is a section taken along line 3 3 of FIG. 1;

FIG. 4 is a plan view of a second embodiment in accordance with the present invention;

FIG. 5 is a bottom plan view of the tray of FIG. 5;

FIG. 6 is a section taken along line 6 6 of FIG. 4;

FIG. 7 is a top plan view of a third embodiment in accordance with the present invention;

FIG. 8 is a bottom plan view of the tray of FIG. 7;

FIG. 9 is a section taken along line 9 9, partly broken away;

FIG. 10 is a section taken along line 10 10 of FIG.

FIG. 11 is a top plan view of a fourth embodiment in accordance with the present invention;

FIG. 12 is a bottom plan view of the tray of FIG. 11;

FIG. 13 is a sectional view partly broken away along line 13 13 of FIG. 11; and

FIG. 14 is a sectional view taken along line 14 14 of FIG. 11.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS Noting FIG. 1, it will be seen that a tray is provided, primarily intended for the packaging of produce, although any food product may be packaged therein, in association with an overwrap film of transparent material such as plastic film or heat-sealable cellophane. As is conventional, the food tray 10 has two upwardly and outwardly inclined opposite side walls 16 and two upwardly and outwardly inclined opposite end walls 18, both the end walls and side walls being preferably bowed as described in the Reifers US. Pat. 3,185,371. As is conventional, each adjacent end and side wall merges as at a rounded corner 20, and the side and end walls terminate at their upper end in a downwardly and outwardly extending peripheral lip 22.

Instead of having a flat bottom wall as is conventional, the tray 10 is provided with a plurality of ribs 24 extending along the bottom generally parallel to the side walls 16; and, preferably at right angles thereto, a plurality or ribs 26 extending generally parallel to the end walls 18. As best seen in FIG. 3, these ribs form, in cross-section, an upright V-shape the walls of which are generally inclined at an angle of about 5 to with their apices 28 forming the external bottom of the tray; if desired, however, the ribs may be made fatter or wider in which case the external bottom of the tray lies in a plane above the true, imaginary apices of the ribs.

It is also clear from inspection that the terminal portions 30 of the V-legs form the internal bottom of the tray upon which the produce or other food product rests. The tenninal portions 30 of the upright V-legs are not so sharp that the food product is in any way cut, bruised or otherwise damaged. When the tray is intended for produce or hamburger, it is preferred that it be fabricated so that the interior of the V-ribs be essentially filled in.

An important feature of the present invention involves the height of the upright V-shaped ribs 24 and 26. It will be noted best from FIG. 3 that the height of such ribs is on the order of about five times the thickness of the material forming the side and end walls of the tray, in this illustrated embodiment. From this it will be understood that the ribs 24 and 26 are of substantial height to provide 'a fixed platform or pallet upon which the food product is supported. It will also be noted that the material forming the ribs in crosssection is thicker than the material forming the side walls, and such thickness may be controlled during the molding operation. The volume of material provided in the upright V-shaped ribs 24 and 26 which form the platform is about equal to the volume of a flat, solid bottom of equal area which would be found in a conventional tray of equal size, wherein such flat, solid bottom would have a material thickness about the same as the side and end wall thickness. By providing a ribbed construction of such volume in accordance with the present invention, a sufficient section modulus is obtained so that the tray 10 will have proper strength to resist normal handling, to prevent inward collapse during overwrapping, and to provide sufficient beam strength.

In accordance with the present invention, and to insure that there are no fault lines as the ribs approach the end to end side walls, there is provided a peripheral gutter-like bottom portion 32 which has an internal depth the same or approximately the smae as the internal depth of the V- ribs 24 and 26. This peripheral groove 32 is formed by two walls, an inner peripheral wall 34 and an outer peripheral wall 36. The inner peripheral wall 34 is preferably of the same slope and the same height as one of the inner walls of the V-shaped ribs 24 and 26; however, the outer peripheral wall 36 is relatively steep and does not rise to as great a height, i.e., it terminates in a plane lower than a plane passing through the upper terminal portions 30 of the V- ribs 24 and 26.

The outer peripheral wall 36 of the peripheral groove or gutter-like portion 32 in turn merges with a generally annular, planar bottom portion 38. As best seen in FIG. 1, it will be understood because of the bowed nature of the side and end walls 16 and 18, the annular planar bottom wall 38 becomes very small, in many cases disappearing, in the area of the corner portions 20. The annular bottom wall 38 in turn blends into the side walls 16 and the end walls 18 along a rounded or curved portion 40.

Referring to the outer surface of the tray 10, as best seen in FIGS. 2 and 3, it will be noted that the annular, planar bottom 38, lying outside of the groove 32, is provided with a bottom surface 38 which is raised a considerable distance above the true bottom of the tray defined by the outer apices 28 of the upright V-shaped ribs 24 and 26. A relatively steep outer annular wall 36 is provided which connects the outer apex 32 of the peripheral groove 32 with the bottom 38 of the annular planar bottom wall 38, such annular wall 36' laying opposite groove wall 36 through the thickness of such groove wall.

Noting FIGS. 4-6, there is shown a tray 100, particularly designed for the packaging of soft produce, intended to be overwrapped by a suitable transparent film. The tray has two opposite upwardly and outwardly inclined side walls 116 and two opposite upwardly and outwardly inclined end walls 1 18, such end walls 118 extending upwardly to a greater height than the side walls 116 to afford greater protection to easily bruised fruit intended to be packaged therein. Adjacent end and side walls merge at rounded corners 120. If desired, suitable denesting ledges 112 and 114 maybe provided at the corners of the end walls 1 l8 and along the side walls 116, respectively.

.As with the embodiment of FIGS. l-3, the tray 100 has a plurality of ribs 124 along the bottom generally parallel to the side walls 116 and a plurality of ribs 126 generally parallel to the end walls 118, defining open windows of generally rectangular configuration therebetween, although such windows may be circular. As seen in FIG. 6, such ribs are V-shaped in cross-section having walls inclined at an angle of about 5 and with the inside of the V-ribs being almost completely filled m."

The end walls 118 and side walls 116 curve and merge into the bottom along an annular transition zone 138. Such annular transition zone 138 in turn merges into the outer peripheral rib 132'. If desired, a slight indentation 132 may be provided along the top of the outer peripheral rib 132' thereby providing a peripheral gutter as in the embodiment of FIGS. 1-3.

The embodiment of FIGS. 7-10 is similar in many respects to the embodiment of FIGS. 4-6. The tray 200 of FIGS. 7-10 is primarily designed for the packaging of soft produce, such as three tomatoes. The tray 200 has two opposite upwardly inclined side walls 216 which extend directly from the bottom of the tray in a manner described below in greater detail. Extending out from the side walls 216 are denesting ledges 214. The tray 200 also has two opposite upwardly and outwardly inclined end walls 218 which extend upwardly to a greater height than the side walls 216 to afford greater protection to the easily bruised fruit intended to be packaged therein.

As with the other embodiments, the tray 200 has a plurality of ribs 224 along the bottom generally parallel to the side walls 216 and a plurality of ribs 226 generally parallel to the end walls 218, thereby defining open windows of generally rectangular configuration. As clearly seen in FIGS. 9 and 10, such ribs are almost U- shaped with the inside of the U-ribs being almost completely filled in. In this embodiment the ribs are about 3/16 inch in height.

It will be noted, particularly from FIGS. 8, 9 and 10 that each rib 224 and 226 has respectively associated therewith a horizontal flange portion 224 and 226'. The width of such flanges 224 and 226 varies from a narrow point at the midpoint between two rib intersections to a maximum thickness at the point closest to the rib intersection, and this gives the ribs a slightly undulating configuration. At the point where the horizontal flange portions 224' and 226' are narrowest, namely midway between rib intersections, the width or thickness of the ribs including the flange portions are, in the present embodiment, about 5/16 inch; and the openings between ribs are about 13/16 inch square.

One of the major differences between the tray 100 of FIGS. 4-6 and the tray 200 of FIGS. 7-10 involves the greater window area in the tray 200. This is primarily accomplished by extending the windows very close to the end walls 218 and immediately adjacent to the side walls 216. Here the transition zone between the open bottom portion and the side and end walls constitutes an annular or-boundary rib 232'. As can best be seen in FIG. 10 the outer edge of the peripheral or boundary rib 232 continues to extend upwardly to form a continuous surface of constant slope with that portion of the side wall 216 below the denesting rib 214.

The tray 300 of FIGS. 11-14 is essentially the same as the tray 200 of FIGS. 7-10, except that it is larger. These two trays 200 and 300 constitute a preferred form of the present invention. Like tray 200, it will be understood that tray 300 has end walls 318 and side walls 316, and open bottom portion defined by intersecting U or V-shaped ribs 324 and 326 wherein the open windows extend very close to the side and end walls to maximize visibility. The transistion zone between the open bottom portion and the side and end walls is defined by an annular boundary rib 332.

It will be understood that the method of fabrication does not constitute a part of the present invention and that any known fabrication method may be used. Normally, the preferred methods of fabrication involve various molding procedures.

While the tray of the present invention is preferably formed of conventional wood pulp stock which may be molded from a water slurry, it will be understood that the ribs may be made of harder paper stock, or such ribs may be specially pressed or otherwise treated. If desired, the tray may be formed of other, equivalent material, it being understood that the scructural advantages of the tray of the present invention derives from its geometrical configuration. For example, the tray may be formed of a structural plastic foam, such as cellular polystyreen foam comprising on the order of percent void space, or porous polyolefin material or other open cell plastic, or a biodegradable plastic such as special biodegradable foam polystyrene. If formed of material having different characteristics than the preferred molded wood pulp, various changes in the configuration may be necessary and, depending upon the material, certain advantages may be absent.

The tray of the present invention has many advantages, a number of which have been delineated above. In brief, however, it may be noted:

Visibility Both sides of the packaged food, such as produce or hamburger, may be viewed, providing up to 55-85 percent view of contents depending in part upon the height of the opaque side and end walls. The bottom of the food product viewed through the windows between ribs is very easy to see since the light, passing along the sides of the ribs, fully illuminates the bottom of the packaged product without casting any shadows. In actuality, an improved visibility may be provided compared to clear plastic trays which introduce an added layer of plastic in addition to the overwrap film, and which collect moisture often impairing vision.

Strength Added beam of structural members across bottom adds stiffening. Tray easily resists all types of normal handling: (1) The tray has sufficient strength to resist handling during wrapping; compression of film on the inward side wall is the main force which tends to cause side wall deformation or collapse, but the present tray resists such deformation or collapse. (2) The tray resists handling in the store and by consumer at home; insufficient beam strength of package for weight of contents may tend to deform or break the package when it is lifted, but the tray of the present invention tends to resist such deformation or breakage.

Breathability The open structure promotes oxygen transfer which, for the packaging of meat in particular, maintains better food product color. This provides for maintenance of meat bloom and quality over the extended period for store sale and home storage.

Juice Control When the material is made of wood pulp or other porous material exuding liquid tends to be accepted. This controlled acceptance of free liquids enhances appearance and prolongs the life of the food.

Nestable with Automatic Denesting Trays nest closely for economical storage and shipping; yet the partially or completely filled-in ribs provide for automatic denesting.

Refrigeration Beam bottom construction holds food products suspended, providing improved air circulation for oxygenation, improved cooling and water evaporation where it occurs, such as in meats, without loss of nutrients.

The trays of the present invention also have no problem of either cutting overwrap film or causing any damage to the packaged food product, particularly when the tray is formed of molded wood pulp. This is so because the edges of the wood pulp are soft and provide a soft support for the food product and also protect the film which contacts the tray.

When formed of the preferred material, molded wood pulp, the tray of the present invention is preferably formed or preformed using a female die, directly contrary to the normal practice wherein a male die is used as the deposition form for molded wood pulp food trays. By the expedient of using such a female die, the screen or finished surface is provided on the outside of the tray, while the inside has a rougher and softer finish, such softer finish serving to enhance the protection of the food product packaged therewithin, while minimizing bruising or other damage. Also, by using a female die, the pulp deposits to a greater thickness in the troughs of the V-shaped ribs, and this may be easily controlled, as indicated above, by the angle of the V, it being understood that the narrower the angle, the greater the pulp will fill in on the interior of the V- shaped ribs 24 and 26, thereby providing more of a cushion surface on the inside of the tray.

A characteristic of molding a tray from wood pulp followed by free drying, is the tendency of the tray bottom to warp upwardly during drying to provide a convex bottom on the inside. This characteristic is disadvantageous since the finished trays unless specially treated such as by form drying, after pressing, etc. will have a slightly concave external bottom which tends to inhibit film sealing when overwrapping the package. This also occurs in a ribbed open bottom tray when a male die is used.

The use of a female die, on the other hand, tends to produce a downward arch which pushes against the flat drying support during free drying, tending to produce a virtually warpage free bottom at improved manufacture speed, without adversely affecting film selaing during packaging.

It is to be understood that the invention is not limited to the embodiments disclosed which are offered illustratively, and that modifications may be made without departing from the invention; for example, variations in the spacing, height and arrangement of the ribs and the windows may be made (e.g., the windows may be round, rectangular, diamond-shaped, etc.; the ribs may join rather than cross so as to provide a brick-work or staggered rectangular window pattern), and variations in the merger configuration between the walls and bottom of the tray may be made.

What is claimed is:

1. ln a generally rectangular molded tray primarily for the packaging of food in conjunction with the transparent overwrap film heat-sealed thereabout, said tray comprising a pair of upwardly and outwardly inclined opposite side walls, each of said side walls forming a long side of said tray; and a pair of upwardly and outwardly inclined opposite end walls, each said end wall being adjacent to each said side walls and disposed at generally right angles thereto and thereby forming the rectangular configuration of said tray; the improvement comprising:

means for providing visibility to the bottom of the tray and for supporting the food at the bottom of said tray, said means comprising a plurality of ribs having an upright V-shaped cross-section, said ribs extending at least partly across said tray in at least two directions to define therebetween a plurality of open windows, said ribs forming the tray bottom having a volume substantially equal to the volume of a bottom of a tray of equal size having a flat, solid bottom.

2. A tray in accordance with claim 1 molded of wood pulp.

3. A tray in accordance with claim 1 wherein said end and side walls are of bowed construction.

4. A tray in accordance with claim 1 further comprising an annular V-shaped rib extending around the periphery of the bottom portion and to which said ribs extend.

5. A tray in accordance with claim 4 wherein said annular rib in the areas of said side walls extend upwardly and directly and smoothly merge into said side walls.

6. A tray in accordance with claim 1 wherein the thickness of material from which said tray is made is greater in the area of said V-shaped ribs such that said ribs are filled in to a large extent on the inside of said tray.

7. A tray in accordance with claim 1 molded of wood pulp with a screen textured outer surface. I

8. A tray in accordance with claim 1 wherein some of said ribs extend across said tray generally parallel to said side walls, and the remainder of said ribs extend across said tray generally parallel to said end walls, said ribs crossing at substantial right angles to define said open windows.

Claims (8)

1. In a generally rectangular molded tray primarily for the packaging of food in conjunction with the transparent overwrap film heat-sealed thereabout, said tray comprising a pair of upwardly and outwardly inclined opposite side walls, each of said side walls forming a long side of said tray; and a pair of upwardly and outwardly inclined opposite end walls, each said end wall being adjacent to each said side walls and disposed at generally right angles thereto and thereby forming the rectangular configuration of said tray; the improvement comprising: means for providing visibility to the bottom of the tray and for supporting the food at the bottom of said tray, said means comprising a plurality of ribs having an upright V-shaped cross-section, said ribs extending at least partly across said tray in at least two directions to define therebetween a plurality of open windows, said ribs forming the tray bottom having a volume substantially equal to the volume of a bottom of a tray of equal size having a flat, solid bottom.

2. A tray in accordance with claim 1 molded of wood pulp.

3. A tray in accordance with claim 1 wherein said end and side walls are of bowed construction.

4. A tray in accordance with claim 1 further comprising an annular V-shaped rib extending around the periphery of the bottom portion and to which said ribs extend.

5. A tray in accordance with claim 4 wherein said annular rib in the areas of said side walls extend upwardly and directly and smoothly merge into said side walls.

6. A tray in accordance with claim 1 wherein the thickness of material from which said tray is made is greater in the area of said V-shaped ribs such that said ribs are filled in to a large extent on the inside of said tray.

7. A tray in accordance with claim 1 molded of wood pulp with a screen textured outer surface.

8. A tray in accordance with claim 1 wherein some of said ribs extend across said tray generally parallel to said side walls, and the remainder of said ribs extend across said tray generally parallel to said end walls, said ribs crossing at substantial right angles to define said open windows.

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