US3550835A

US3550835A - Package,especially for food products

Info

Publication number: US3550835A
Application number: US728407A
Authority: US
Inventors: Karl Rune Persson
Original assignee: Sprinter Pack AB
Current assignee: Sprinter Pack AB
Priority date: 1967-05-17
Filing date: 1968-05-13
Publication date: 1970-12-29
Anticipated expiration: 1987-12-29
Also published as: SE329804B; FI47073B; DK116647B; AT294687B; NO125622B; FI47073C; DE1761378A1; DE1761378B2; FR1565898A; GB1227815A; DE1761378C3

Description

United States Patent lnventor Appl. No. Filed Patented Assignee Priority Karl Rune Persson Halmstad, Sweden 728,407

May 13, 1968 Dec. 29, 1970 Sprinter Pack AB Laholmsvagen, Halmstad, Sweden a corporation of Sweden May 17. 1967 Sweden PACKAGE, ESPECIALLY FOR FOOD PRODUCTS 4 Claims, 7 Drawing Figs.

U.S. Cl 229/31, 229/32 Int. Cl B65d 5/24 Field of Search 229/35, 31,

[56] References Cited UNITED STATES PATENTS 1,699,008 1/1929 Miller 229/31(i) 3,298,593 l/l967 Stephenson.... 229/5l(is) 3,316,102 4/1967 Doll et al. 229/3l(i) FOREIGN PATENTS 6,513,809 4/1967 Netherlands 229/31 Primary ExaminerDavid M. Bockenek Attorney-Bauer and Goodman ABSTRACT: A package for food products comprising a single blank carton tray and a separate cover. The blank of the tray has corner portions foldable to three sectors forming a corner post of triangular cross section in the erected tray. The wall panels have upper edge flaps connected at their ends by connecting flaps formed as extensions of the upper ends of the central sectors of the post. The corner is sealed to the frame formed by the edge flaps and the connecting flaps.

PATENTED DEE29 I976 SHEET 1 BF 3 FIG] PATENTEU DEB29 19m SHEET 2 UF 3 PATENTED 05:29 I970 SHEET 3 BF 3" INVENTOR. Km! Rune Pensson PACKAGE, ESPECIALLY FOR FOOD PRODUCTS This invention relates to a package which is primarily intended for food products, especially food products which have to be heated in the package by placing the package in a highfrequency oven, a heating bath or on a heating plate. However, the package according to the invention may also be advantageously used for food products which need not be heated, but nevertheless should be enclosed in a sealed package.

Hitherto, trays of plastic material or aluminum foil have been used for packing ready-cooked food in so called portion packages. However, the plastic trays are usually made of a plastic material which does not withstand heating in a highfrequency oven or on a heating plate up to about 120 C. Trays of aluminum foil are electrically conductive and for this reason they cannot be used for heating in high-frequency ovens. Another inconvenience of such trays is a certain difficulty to apply thereto printed text or pictures, such as for instructions and advertisement. All of these inconveniences can be avoided if the tray is made of carton material which withstands temperatures up to usual heating temperature of about 150 C. and in addition thereto can be readily provided with printed text and pictures.

In accordance therewith the object of the invention is to provide a carton package of sufficient tightness, strength and stability so as to be able to be heated in an oven or on a heating plate and which is easy to open and sufficiently rigid to be used itself as a dish or plate from which food can be eaten, if desired. Further, the package should be erected from a blank which may be mechanically erected and sealed.

For this purpose the invention embodies a carton tray which can be mechanically erected so as to form a fluid-tight tray. The tray is erected from a blank which at least on one side has a fluid-tight plastic coating which is adapted to be sealed and withstands heating to about 150 C., such as polypropylene. In order to obtain fluid-tight corners a blank is used which by fold lines is subdivided into a bottom panel and four wall panels which at their ends are connected to each other by corner portions which by means of fold lines are subdivided into three sectors, a central sector and two lateral sectors, extending from a common apex at the adjacent corner of the bottom panel, wherein each lateral sector is in contact with the adjacent wall of the erected tray and together with the central sector forms a corner post of triangular cross section. Such a tray which is known per se is devised according to the invention with supplementary details in the manner indicated in the annexed claims in order to form, together with a cover, the package according to the invention.

Two suitable embodiments of the package according to the invention are explained more in detail with reference to the annexed drawings.

FIG. 1 is a perspective view of a cover for the package according to the invention, FIG. 2 is a perspective view of a carton tray of the package according to the invention with part of a corner broken away, FIG. 3 illustrates the blank for making the tray shown in FIG. 2, FIG. 4 illustrates a corner portion of another blank for erecting the tray of a second embodiment of the invention, all corners of the blank being identical, FIG. 5 is a diagrammatic perspective view of the tray corner erected from the blank in FIG. 4 partially broken and seen from the inside of the tray, FIG. 6 is a diagrammatic perspective view of the corner in FIG. 5 seen obliquely from above and partially open before sealing the details of the corner, and FIG. 7 illustrates another embodiment of the cover to be sealed to the tray in FIG. 1 or 5, respectively.

The covers shown in FIGS. 1 and 7 as well as the blank of the trays shown in FIGS. 3 and 4 consist of a cardboard or carton material which at least on the side facing the interior of the tray has a fluid-tight coating adapted to be sealed, which may be a plastic coating, such as polypropylene. Text and pictures may be printed on the external sides of the tray and the cover. However, normally it is preferred to have a plastic coating on both sides of the tray blank in order to enable sealing by means of the plastic coating when erecting the tray.

The blank shown in FIG. 3' is by fold lines subdivided into a bottom panel 10 and four wall panels 11, I2, 13, 14. The ends of the wall panels merge into comer portions which by means of two

fold lines

16, 17 are subdivided into a central sector 18 and two

lateral sectors

19, 20; At each comer the angle between the

fold lines

21, 22 which define the end edges of the wall panels is less than 90 so that when erecting the tray the wall panels will be obliquely inclined toward the bottom 10. This tapering shape of the tray increases the stability of the tray and facilitates emptying thereof.

The central sector 18 has an upper extension in the form of a connecting flap 23 adapted to be folded about a fold line 24 which defines the upper edge of the central sector.

Incisions

25, 26 extend through some distances from the ends of and along the fold line 24 to provide for a special character of the tray in the manner described hereinbelow.

Along the outer or upper edges of the wall panels of the tray there are provided

edge flaps

27, 28 which: at their ends are beveled such that they fit each other upon erection of the tray and form a frame as shown in FIG.2.

In order to erect the blank, the corner portions 15 are folded inwardly and the

edge flaps

27, 28 are turned outwardly into a plane which in the erected tray is parallel to the bottom of the tray. The connecting flaps 23 are turned outwardly and downwardly over the underlying end portions of the edge flaps and are secured thereto by any suitable sealing process. The result is a closed frame having strong joints at the corners. Due to the double inward folding of the corner portions such that the

lateral sectors

19, 20 are disposed along the insides of the wall panels of the tray, corner posts will be formed at the corners of the tray. These corner posts are in the form of pyramids having downwardly pointing apexes. The connecting flap 23 is an extension of the central sector 18 of the respective comer'post and is secured to the edge flaps by sealing. As a result, the corner post will form a stiff structure which can take considerable loads without being deformed.

Although the tray can be used without the

incisions

25, 26, these incisions result in an advantage because the middle portion 29 of the central sector 18 (FIG. 2) is located between the end of the incisions in the central sector and can thus be pressed inwardly into a position in which this middle portion 29 makes a substantially right angle with the bottom of the tray which facilitates the erection of the tray in an erecting machine. The

incisions

25, 26 thus make possible the illustrated pressing of the central sector 18 which is effected during the erection of the tray without the necessity of additional fold lines. The remaining marginal portions 30 of the central sector 18 are forced into tight contact with the

lateral sectors

19, 20 and may be attached to them by sealing, if desired.

As shown in FIG. 1, the cover 31 has weakening

lines

32, 33 in its plastic coated underside which extend along the margins of the cover at such distances as to define

marginal strips

34, 35 of substantially the same width as the edge flaps of the tray. By means of these marginal strips the cover is sealed to the edge flaps of the tray, such as by application of adhesive stripes which may be heated immediately before the sealing operation. Instead thereof, the sealing operation may be effected immediately after the application of the adhesive stripes and before these stripes have set. However, in many instances the plastic coating on the underside of the cover and the plastic coating on the edge flaps will be sufficient to effect the necessary seal when pressed together and heated.

The weakening

lines

32, 33 define two tear-off tabs 36. If one of these tabs is torn off the entire cover portion 37 between the weakening lines will be torn off whereas at least some layers of the

marginal strips

34, 35 remain on the edge flaps and form an additional reinforcement thereof during the continued handling of the tray after the tray has been opened.

In cases in which the package has to be heated it may sometimes be suitable to leave the portions below the tear-off tabs 36 unsealed so as to provide leaking gaps for vapor generated during heating of the food product.

The embodiment shown in FIGS. 4 to 7 will form a package which has not cut edges facing .the interior of the closed package as in the tray in FIG. 2 where the cut edges of the

incisions

25, 26 are exposed to the food product in the tray In some instances the food product may contain liquids which colours the cut edges and when this is not desired for aesthetic reasons, the embodiment in FIGS. 4 to 7 is preferred. This embodiment will also be more effectively sealed due to the fact that the edge flaps and the cover form a continuous sealed frame as will be understood from the cover shown in FIG. 7.

As shown in FIG. 4 the bottom 10 and the wall panels connected thereto and provided with edge flaps are substantially identical with corresponding details in FIG. 3. However. the

fold lines

37, 38 defining the ends of two

adjacent wall panels

39, 40 are at right angles and enclose a corner portion divided .by

fold lines

41, 42 into a central sector 43 and two

lateral sectors

44, 45. At the end of the central sector is a fold line 46 forming a hinge for a connecting flap 47 having its sides connected with the

edge flaps

48, 49 through intermediate

edge flap portions

50, 51, which are hingedly connected with the adjacent lateral sector along a fold line 52, which may be a slit if desired, and are foldable at their ends along

fold lines

53, 54

for creating the tray as illustrated in FIGS. 5 and 6.

As will be understood from FIGS. 5 and 6 each corner of the tray will have folded

edges

46 and 54 which do not expose any cut edges to the interior of the tray. Furthermore, the intermediate edge flap portions 51 will contribute to the strength and sealing of the corner.

The cover to be sealed 0n the frame formed by the

edge flaps

48, 49 and the connecting flaps 47 is shown in FIG. 7 and is generally denoted by 55. One side of the cover is coated with a thermoplastic layer which is cut through along a continuous incision line 56. However, the incision has merely a depth into the outermost layers of the carton material of the cover for reasons given below. At one corner a straight incision line 57 forms a tab 58 to be used when tearing off the cover. Adjacent the tab the incision line 56 is somewhat retracted to form an inner tab 60 which is located outside the effective area of the heat sealing tools. When tearing off the cover, merely the carton layers nearest the sealed layers of plastic coating will remain, whereas the other layers of the frame outside the line will be removed together with the portion of the cover located inside the line 56. The remaining heat sealed material on the edge flaps 48, 49 will form a closed frame reinforcing the tray when the cover has been removed.

Although it is not shown in the drawings, it should be understood that the sealing of the cover to the edge flaps is effected upon heating and under relatively high pressure, so that the connecting

flaps

23 and 47, respectively, will be pressed substantially flush with the edge flaps to eliminate the step between the connecting flaps and the edge flaps.

If desired, the package according to the invention may also be used for food which has not to be heated. In this case the cover may be a transparent foil.

Iclaim:

1. A package especially for food products and consisting of a carton tray closed by a cover and made from a single carton blank which on the side facing the interior of the tray has a fluid-tight coating and is subdivided by fold lines into a bottom panel and four wall panels connected at their ends to each other by corner portions which by means of fold lines are subdivided into a central sector and two lateral sectors extending from a common apex at the adjacent corner of the bottom panel, characterized in that in the erected condition of the tray each lateral sector is in contact with the adjacent wall panel of the erected tray and said adjacent wall panels define an external corner of said tray and the central sector has an operative position located in front of said external corner and cooperating therewith to define a comer post of triangular cross section, the upper edges of the wall panels of the tray have extensions in the form of edge flaps which are folded outwardly and form a frame in a plane parallel to the bottom of the tray, the end portions of the edge flaps being connected to each other by a connecting flap which is formed by an extension of the upper end of the central sector of the respective corner post and is folded over the end portions of the edge flaps and sealed thereto, and in that the cover is sealed to the edge flaps and connecting flaps.

2. A package as claimed in claim 1 wherein the wall panels of the tray make obtuse angles with the bottom of the tray so as to form a conical tray, characterized by incisions along the ends of those fold lines by which the central sector is articulated to the appertaining connecting flap, and in that the middle portion of the central sector located between the inner ends of said incisions has been pressed toward the adjacent wall panels into a position substantially at right angles to the bottom of the tray, whereas the marginal portions of the central sector have been folded into contact with the lateral sectors.

3. A package as claimed in claim 2, characterized in that the marginal portions of the central sector are sealed to the wall panels of the tray.

4. A package as claimed in claim 1 having a cover of carton material coated with a layer of plastic material on its underside, characterized by an incision line having a depth to cut through the plastic layer and through a number of layers of the carton material, said incision line defining the major portion of the cover located inside the edge flaps and adapted to be removed by tearing up one corner of the cover from its connection with the underlying connecting flaps.