RU235857U1 - FOOD CONTAINER - Google Patents

Abstract

The utility model relates to packaging made of laminated cellulose-paper material intended for placing and storing mainly liquid and fat-containing food products, such as sour cream, milk, juice, yogurt, etc. The container for food products has the shape of a cup with an overlapping side seam and is made of a two-layer sheet material including a cardboard layer and a polymer layer forming the inner surface of the cup. The edge of the blank, forming the overlapping seam and extending inside the formed volume, has a cardboard layer cut at an angle, wherein the cut is made along the width of the formed seam to a residual cardboard thickness at the end of no more than 0.2-0.1 mm. The inclined cardboard surface formed as a result of the cut is applied to the polymer layer of the mating edge of the blank and connected to it by means of heat sealing under pressure. 3 clauses, 8 figs.

Description

The utility model relates to packaging made of laminated cellulose-paper material, intended for the placement and storage of mainly liquid and fat-containing food products, such as sour cream, milk, juice, yogurt, etc.

There are many laminated cardboard containers on the market in the shape of a cup with a round bottom and a conical or cylindrical body. As a rule, the blank for the cup body is cut from a sheet material and given the desired shape by wrapping it around a mandrel so that one side edge of the blank overlaps the other edge, thus forming a straight, overlapping seam running along the height of the cup.

For such packaging, there is a problem of the negative impact of aggressive components of the product placed in the container (water, organic fats and acids) on the paper-cellulose layer through the unprotected cut end of the blank edge, forming a seam and coming out into the internal volume of the container. Through the unprotected end, the liquid contents of the container are absorbed, which leads to the cardboard getting wet, reducing its rigidity, and breaking the tightness of the packaging.

There are several known solutions to the problem of protecting cut ends. A cup made of heat-sealable cardboard is known, containing a fibrous base and a layer of polymer coating on one side, forming the inner surface of the cup (see patent RU 2480551, IPC: B65D3/00, published 27.04.2013). To reduce the absorption capacity through the untreated end edge, the fibrous base contains a hydrophobic adhesive substance on the inner seal of the cup. However, such a solution can only be used in disposable drinking cups and cannot be used in packaging for long-term storage of products. A known packaging material is a cardboard/polymer composite, comprising a closed shell with a longitudinal overlap seam, a bottom welded to the lower end of the shell, and a wraparound flange made at the upper end of the shell for securing the lid (see patent RU 2425785, IPC: B65D3/00, published 27.04.2013, Fig. 2, 2c). To prevent contact between the cardboard layer and the contents of the packaging, a polymer tape is used, U-shaped around the edge to be protected and sealed by heat welding.

The disadvantage of this solution is the additional thickening and excessive rigidity of the material obtained in the overlap seam area, which complicates the subsequent forming of the bottom of the package and prevents high-quality rolling of the upper edge.

Most often in the production of cups and tubular containers, the method of bending the edge is used to protect the cut side ends: the inner or both connected edges of the blank (for example, see the design of a waterproof paper vessel, patent JPS 5852033, IPC: B65D3/28, 28.03.1983). However, in this case, there are already three or even four layers in the seam area, forming a thick fold. Strong thickening creates difficulties for subsequent sealing of the container bottom and forming a flange for the lid, requiring the use of special folding equipment. In addition, cracks often form in the thick seam area, which leads to a violation of the tightness of the package, leakage of contents, and air ingress.

To avoid excessive compaction in the seam area, the thickness of the cardboard layer of the folded edge is trimmed, for example, see patents WO 9208652, 29.05.1992; EP 2604539, 19.06.2013; JPS 59115715, 04.08.1984; JP2013043684, 04.03.2013; JPS57107711, 02.07.1982; JP 2006273396, 12.10.2006; US5810243, 22.09.98 and others.

The trimming is performed mainly by half the thickness of the cardboard layer and the thinned part of the edge is folded, bending it towards itself (folding in half) and hiding the cut edges of the material inside. In this case, the thickness of the untrimmed material of the workpiece is obtained along the edge, which means that the seam does not thicken.

In some cases, the edge strip is milled more deeply, to a small residual thickness of the cardboard, approximately comparable to the thickness of the protective polymer layer, while the trimmed section is folded over (overlapped) onto the untrimmed part, for example, see patent WO 9208652 or EP 2604539. In these cases, the formed side seam also thickens with all the ensuing consequences.

Another disadvantage of this technology is that special equipment is required to perform the operation of folding the edge of the workpiece, which significantly complicates and increases the cost of the packaging manufacturing process.

The closest analogue for the claimed solution is a package with a hermetic end of an overlapping seam, the design of which is disclosed in the patent for utility model RU 189037, IPC B65D5 / 40, B65D3 / 22, published. 07.05.2019. The known packaging is made of a form-forming material consisting of a frame material (cardboard) and a protective layer of a biodegradable polymer, which is applied only to the inside of the frame material and is made elongated relative to it. At the place of formation of the seam, the elongated protective layer is connected to the mating layer of the form-forming material, without touching the end surface of the seam.

Features similar to the claimed technical solution are: the production of a food container packaging in the form of a cup with an overlapping side seam obtained by rolling up the blank with the edges to be joined, and the production of a container from a two-layer sheet material, including a frame layer of cardboard and a protective polymer layer applied only to one side of the cardboard and forming the inner surface of the cup during molding.

Firstly, the disadvantage of the closest analogue is the difficulty of forming an increased protective layer extending beyond the end of the cardboard. This solution involves the use of an original, specially developed technology for the production of the blank material. However, traditionally, in the mass production of such containers, the blank of the required shape is cut out of ready-made laminated cardboard. In this case, it is not possible to separate the protective polymer layer from the cardboard layer.

Secondly, it is assumed that the extended protective layer is connected to the mating layer of the forming material without touching the end surface of the seam. With such a connection, a cavity is inevitably formed in the seam area, into which the unprotected end of the material emerges. The lack of tightness of the connection in the seam area can lead to damage to the thin protective layer and moisture getting into the cavity. Thus, the known solution does not completely eliminate the problem of end absorption.

The proposed utility model is aimed at creating packaging devoid of the above-mentioned drawbacks, characterized by increased tightness of the side seam and the possibility of manufacturing on standard, available equipment. The technical result achieved when using the utility model consists in obtaining a comparatively thin, but at the same time mechanically strong and tight side seam with overlap, using standard, widely available equipment.

Disclosure of the essence of the utility model

The technical result is achieved in the proposed container for food products, having the shape of a cup with an overlapping side seam obtained by rolling the blank with the overlapping edges, made of a two-layer sheet material including a cardboard layer and a polymer layer applied to one of its sides, forming the inner surface of the cup. According to the claimed utility model, the edge of the blank, forming the overlapping seam and extending inside the formed volume, has a cardboard layer cut at an angle, wherein the cut is made along the width of the formed seam, at an angle of 5 to 30° to a residual cardboard thickness at the end of no more than 0.2-0.1 mm, and the inclined cardboard surface formed as a result of the cut is superimposed on the polymer layer of the mating edge of the blank, to which it is connected by means of heat sealing under pressure.

In preferred examples of the implementation of the utility model:

- the width of the overlap seam is 10 mm.

- the thickness of the cardboard layer is 0.4 mm. Unlike the closest analogue, which requires a special technology for manufacturing the material, in the proposed solution the blank is cut out of a sheet of cardboard laminated on one side in a known manner. On the resulting blank, on one side, which forms the edge going inside the formed volume of the glass (hereinafter referred to as the inner edge), the cardboard layer is cut off, for example, by milling. Moreover, the cut is made diagonally, at an angle (from 5 to 30) ° to a residual cardboard thickness at the end of no more than 0.2-0.1 mm, that is, to a thickness commensurate with the thickness of the polymer layer.

As a result of trimming along the inner edge of the workpiece, an inclined surface is formed with a width approximately corresponding to the width of the overlay, i.e. the width of the seam.

Moreover, unlike other known analogues with edge trimming, in the proposed design the thinned edge is not folded, but is placed on the polymer layer of the mating edge and connected to it in a straightened form by means of heat welding, applying pressure on the section of the inclined beveled surface.

Under the influence of temperature and applied pressure, particles of molten polymer penetrate into the thinned cardboard layer from both sides, and the diffusion of molten polymer particles into the thin paper layer occurs. Due to the fact that the thickness of the cardboard layer is approximately proportionate to the thicknesses of the polymer layers conjugated with it, a comparatively homogeneous composite is formed at the end of the seam, resistant to moisture and aggressive food environments, and at the same time possessing high strength, exceeding the strength of one polymer layer. At the same time, there are no internal voids in the seam zone.

Thus, compared to the closest analogue, a significant increase in the tightness and mechanical strength of the side overlap seam is ensured. At the same time, in the proposed design, the thickness of the material in the side seam area is significantly less than two thicknesses of the workpiece. The resulting thin overlap seam subsequently ensures high-quality formation of the bottom and flange along the upper edge. The essence of the proposed technical solution and the possibility of its industrial applicability are confirmed by the following examples of implementation and drawings, which depict:

Fig. 1 – view of the container body, isometric; Fig. 2 – also, top view;

Fig. 3 – cross-section of the workpiece material;

Fig. 4 and 5 show an example of obtaining a cut edge;

Fig. 6 and 7 show the stages of forming an overlap seam;

Fig. 8 – fragment from Fig. 2, enlarged.

Implementation of a utility model

A container for food products with improved barrier properties, according to the present utility model, has a body 1 in the form of a glass with a side seam 2 running along the height with an overlap (see Fig. 1-2).

As a rule, the glass is characterized by a conical (or cylindrical) shape of the side surface, a round bottom and a flange along the edge of the neck, necessary for subsequent fixation of the container lid. In this application, only the side surface of the body in the part of the overlapping connecting seam is considered. The remaining parts of the container can be any.

The body blank 1 is made of a two-layer sheet material, including a supporting (frame) layer of cardboard 3 and a protective (barrier) polymer layer 4, applied only to one side of cardboard 3 (see Fig. 3).

Polymer layer 4, which serves to form the inner surface of the container and prevents contact of the paper material with the product, must be resistant to moisture and aggressive impact of the product placed in the package. Polymer layer 4 can be made of polyethylene grade LDPE 115, or another hydrophobic material suitable for long-term storage of food products.

The process of making a container includes the following stages.

1) The blank of the required shape is cut out from a sheet of cardboard laminated on one side, which is usually supplied in large rolls and unwound for cutting. The blank is cut out on standard cutting equipment.

2) The workpiece is milled from one side edge, which will be facing inside the formed volume of the glass (see Fig. 4).

Milling is performed on high-speed milling equipment.

The cut is made practically along the entire width of the future seam, at an angle of β = 5 - 30° to a residual thickness (s) of cardboard 3 at the end of no more than 0.2 - 0.1 mm, which is approximately comparable with the thickness of the polymer layer 4 (see Fig. 5). As a result of trimming along the inner edge of the workpiece, an inclined surface 7 is formed with a width approximately corresponding to the width of the seam 2.

3) The blank prepared in this way is given the required shape by wrapping it once around the mandrel with an overlap of the uncut side edge 5 on the cut side edge 6, which goes inside the volume being formed (see Fig. 6). In this case, the inclined surface 7 of the cardboard is placed on the polymer layer 8 of the mating edge of the blank, and is connected to it by subsequent heat sealing under pressure.

The heat sealing operation involves heating the edges of the workpiece to be joined, which can be accomplished, for example, by induction heating, hot air blowing, or ultrasonic exposure.

Under the influence of temperature, the polymer layers in the seam zone are activated and softened, and when pressure is applied, particles of molten polymer penetrate the thinned cardboard layer from both sides, the molten polymer particles diffuse into the thin paper layer, forming a relatively homogeneous composite layer at the end of the seam after cooling (see Fig. 8), resistant to moisture and aggressive food environments, with high mechanical strength, including due to the absence of internal voids in the seam zone.

4) The bottom is welded to the lower end of the body 1 and a wraparound flange is made at the upper end to secure the cover (not shown in the drawings). In this case, the thin seam 2 allows these operations to be performed easily and efficiently.

Thus, the proposed container is characterized by increased tightness, mechanical strength and reduced thickness of the side overlap seam, and can be manufactured on standard and widely available equipment.

Claims (4)

1. A food container in the shape of a glass with an overlapping side seam obtained by folding the blank with the edges to be joined overlapping, made of a two-layer sheet a material comprising a layer of cardboard and a polymer layer applied to one of its sides, forming the inner surface of the glass, characterized in that the edge of the workpiece, forming an overlapping seam and extending inside the volume being formed, has a layer of cardboard cut at an angle, and the cut is made along the width of the seam being formed to a residual cardboard thickness at the end of no more than 0.2-0.1 mm, and the inclined surface of the cardboard formed as a result of the cut is placed on the polymer layer of the mating edge of the workpiece and connected to it by heat sealing under pressure. 2. A food container according to item 1, characterized in that the width of the overlap seam is 10 mm. 3. A food container according to item 1, characterized in that the thickness of the cardboard layer is 0.4 mm. 4. A food container according to item 1, characterized in that the cut is made at an angle of 5° to 30°.