A method for producing a detachably connected container having barrier properties

Procedure to produce a detachably connected container with barrier properties.

Background of the invention

Technical field

The present invention relates to a multipack container assembly detachably connected with barrier properties.

Description of the related technique

Multi-container container assemblies for storing several items separately are known. Individual rations of refrigerated food products, such as yogurts and desserts, as well as many other products, can be individually packaged in multi-container containers of this type. Such multi-container container assemblies typically include several containers that are joined together to form an individual airtight container. Consumers will recognize that each of the containers can be separated from the multipack so that the items inside the containers can be used.

Typically, conventional multi-container container assemblies are made by thermoforming polystyrene. Thermoforming is a widely known process for making containers well known to those skilled in the art. In thermoforming, a thermoplastic resin sheet having a certain thickness can be held in a clamping frame and heated. A furnace or heating station heats the flanges as well as the center of the thermoplastic sheet, so that when the sheet is subsequently supplied to a forming station, a general temperature equilibrium has been achieved. After heating, the sheet is transported to the forming station where, by one of several procedures, it is forced on a mold. The thermoforming of the polyolefin sheet can be carried out by different conventional techniques, for example, a vacuum can be applied in the mold and / or a counter mold can be used to aid in the forming of the sheet in a container. The residual heat of the plastic can be removed after forming. After cooling, the final product is removed from the forming station and sent to a cutting press in which the final product of the web is trimmed.

A disadvantage of polystyrene is that it has low moisture barrier properties. Thus, while polystyrene works well for refrigerated food items, such as yogurt and other desserts, polystyrene containers are not desirable for items such as snack foods with low humidity that require containers that have moisture barrier properties. Unlike polystyrene, polyolefins, such as polypropylene, have excellent moisture barrier properties.

A drawback of the use of polyolefin containers such as polypropylene is that said material has a high tear resistance. Tear resistance measures the tear resistance of a material. Due to the high tear resistance of polypropylene, it is commonly used in "hinges made of the same material". A hinge made of the same material is a flexible plastic hinge that is molded as a piece with the rest of the container or packaging, connecting the upper and lower rigid sections. The properties of the polypropylene material allow the hinge to flex repeatedly over time without cracking or breaking. Thus, polypropylene containers are not suitable for multi-container assemblies connected separately. As a consequence, when it is desired to provide a set of multi-container containers with a polypropylene base, cardboard is used to group several separate containers together. However, the manufacturing process used to produce individual polypropylene containers grouped by cardboard is expensive. Material costs are higher because cardboard must be used in addition to plastic material. In addition, assembly costs are higher as separate machinery is required for handling cardboard to group individual containers together. Another disadvantage of polypropylene containers grouped by cardboard is that the consumer must break the cardboard in order to obtain a container that separates the containers from each other. Once separated, containers can no longer be stored as easily as when they are grouped together.

US Patent Nos. 5,543,104 and 5,409,127 disclose an injection molded container assembly made of high density polyethylene ("HDPE"). Although HDPE containers have moisture barrier properties, HDPE lacks oxygen barrier properties.

To improve the shelf life of a food product contained inside, a plastic food container must have adequate barrier properties to protect the product from migration from moisture or moisture and oxygen in the container. This is typically accomplished by combining, in a layered arrangement, several polymer sheets, each of said sheets having different barrier properties. The typical objective for the construction of said container is to provide in the conglomerate a container of sheets in layers that can be constructed at a minimum cost and, in addition, to provide properties of

adequate barrier to light, moisture and oxygen without any impact on the taste of the product inside the container.

For example, it has been observed that EVOH offers an excellent oxygen barrier that reduces the migration of oxygen in plastic containers. EVOH has been used successfully in combination with, for example, polyethylene or polypropylene (PP), where said polypropylene or PP provides moisture barrier properties for the container. Another benefit of using EVOH in containers for food products is its resistance to the migration of oils and contaminants, both from other layers of leaves that migrate to the product and from the product that are impregnated on the walls of the containers. For example, when recycled swirled polyolefin (PCR) resins are used as one of the sheet layers for a container, it has been found that EVOH is an effective barrier to prevent contaminants from the PCR resin from impregnating a disposed food product in the container. It has also been observed that an EVOH layer is an effective barrier to the removal of the surface layer to prevent the absorption of oil and oil soluble flavors from the packaged food.

It is difficult to foresee how a container provided with a layer arrangement of polymer sheets can be made by an injection molding process, because such a process, by its very nature, cannot provide a layer arrangement, since it must be inject a mixture of liquefied plastic into a mold, resulting in a mixture without an adjacent oxygen barrier layer. In addition, the capital costs associated with injection molded articles are relatively high. As a consequence, there is a need for a method for the realization of a separable container connected in a separable manner, in which said container can provide the manufacturer with the option of a container, either with moisture barrier properties or with barrier properties to Moisture and oxygen.

Document FR2867759 discloses a package consisting of joined and separable containers with a joint area provided therewith. These containers are closed by seals. The containers are produced by thermoforming and have multilayer walls and include an oxygen barrier layer of a metal, ceramic or plastic base material. Such containers may include a polyolefin layer. In the junction zone between two adjacent containers, a breakable part is incorporated that provides a mechanically fragile local area.

Summary of the invention

The proposed invention provides a method of making a multipack container detachably connected, as defined in claim 1.

In one embodiment, the present invention provides a method for making a multipack container assembly connected detachably, which can store products ready for consumption, which can be stored and with low humidity. In one embodiment, the barrier properties are provided by an EVOH film adhered to the polyolefin sheet. The channel disposed between the adjacent container flanges is provided to allow the separation of adjacent containers so as to avoid unintentional breaking of the joint area. All of the foregoing, as well as other additional features of the present invention, will be apparent from the following detailed description in writing.

Brief description of the drawings

The novel features of the invention are indicated in the appended claims. However, the invention itself, as well as a preferred form of use, other objectives and advantages thereof, will be better understood by referring to the following detailed description of the illustrative embodiments, when read in conjunction with the accompanying drawings, in which:

Figure 1 is a perspective view of a six-container thermoformed multi-container container assembly in accordance with an embodiment of the present invention.

Figure 2 is a schematic cross-sectional view of a multilayer sheet incorporating EVOH in accordance with an embodiment of the present invention.

Figure 3 is an end view of the multi-container container assembly shown in Figure 1, showing a fragile area between adjacent container flanges.

Figure 4 is an exploded end view representing the channel shown in Figure 3.

Figure 5 is an exploded view from above representing the channel shown in Figure 3.

Figure 6 is a perspective view depicting the removal of a container from the multipack assembly shown in Figure 1.

Detailed description

Figure 1 is a perspective view of a thermoformed multi-container container assembly 100 showing six containers 110 in accordance with an embodiment of the present invention. Although the thermoforming process is known in the art, as used herein, the thermoforming process should be interpreted to include other equivalent processes, including, but not limited to, pressure forming and vacuum forming processes. The multi-container container assembly 100 comprises a plurality of individual containers 110 in which the periphery of the upper part of each container comprises a flange projecting towards the outside 120. Adjacent containers 110 can be detachably connected by a designed area more fragile 130 disposed between adjacent container flanges 120. As used herein, a channel 130 corresponds to a thin area between the flanges of adjacent containers, which allows said containers to be separated. As used herein "thin area" does not refer to a reduced area as a result of marking or perforation, but means that the thickness of the channel 132 (as shown in Figure 4, mentioned below) It is thinner and has a thickness less than that of flange 120.

In one embodiment, the channel 130 is adjacent only to a part of the length of the container and / or the width of the container. As a consequence, in one embodiment, a portion 140 of the assembly 100 can be cut or trimmed during or after the thermoforming operation. In one embodiment, part 140 is cut in the cutting press after the containers have been formed. Although Figure 1 shows the multi-container container assembly provided with six containers 110, said multi-container container assembly may comprise two or more containers. In one embodiment, the channel 130 can be made in the cutting press after the formation of the containers.

Figure 2 is a schematic cross-sectional view of a multilayer sheet incorporating EVOH in accordance with an embodiment of the present invention. In the embodiment shown, the outer polypropylene layer 212 is adjacent to a recycled recycled resin 214 bonded by a first layer of adhesive 216, such as a modified polyethylene, to an EVOH layer 218. Next, said EVOH layer 218 is bonded by a second layer of adhesive 220 to the recycled interior recycled resin 222. The polypropylene layer on the outermost product side 223 provides a moisture barrier layer.

The resin resin layer 214, 222 can be made from a part of the multilayer sheet that is cut from the area shown with reference number 140 in Figure 1 and returned to an extruder where it can be smoothed and coextruded or laminate on the multilayer sheet that can be used in accordance with the present invention.

In one embodiment, the multilayer sheet comprises a material with moisture barrier properties adhered to a material with oxygen barrier properties, adhered to another material with moisture barrier properties.

In one embodiment, the layer with moisture barrier properties comprises a polyolefin. Any polyolefin with a water vapor transmission rate of less than approximately 25 g / day / m2 (38 ° C, 90% relative humidity) and more preferably less than approximately 4.8 g / day / m2 (38 ° C, 90% of relative humidity) presents the requirements of moisture barrier properties that can be used in accordance with the present invention. In one embodiment, the polyolefin with moisture barrier properties comprises polypropylene, and in an alternative embodiment, said polyolefin comprises high density polyethylene.

In one embodiment, the layer with oxygen barrier properties comprises EVOH. Any polyolefin that has an oxygen transmission rate of less than 1.92 cc / day / m2 approximately (73ºF, 0% relative humidity) and more preferably less than 0.4 cc / day / m2 approximately (73ºF, 0% relative humidity) presents the oxygen barrier properties requirements that can be used in accordance with the present invention.

Figure 3 is an end view of the multi-container container assembly shown in Figure 1, showing an area of ​​fragility 130 or channel between the flanges 120 of adjacent containers 110. Figure 4 is an exploded end view showing the channel which can be seen in Figure 3. For the sake of simplification, the opercle is not shown in Figures 3 and 4. As shown in said Figures 3 and 4, the channel 130 detachably connects the flanges 120 of adjacent containers 110. The channel 130 can be created by a flat mold plate used in the thermoforming process. Said channel 130 can also be created with a blade. The channel 130 a channel thickness 132 and a channel width 134. The channel 130 creates a channel for controlling the tearing of materials such as polypropylene that do not tear easily.

Referring to Figure 4, in one embodiment, the thickness of the channel 132 is less than about half the thickness of the flange 120. An important difference between the thickness of the flange 120 and the thickness of the channel 132 can help ensure that the tearing is in channel 130 and does not travel to

flange 120. In one embodiment, the thickness of the channel 132 is greater than about 0.0254 mm (1 mil). In one embodiment, the thickness of the channel 132 is approximately 0.127 mm (5 mils). In one embodiment, the flange 120 comprises a thickness greater than approximately 0.127 mm (5 mil). In one embodiment, the flange 120 comprises a thickness between approximately 0.254 mm (10 mils) and approximately 1.27 mm (50 mils) before holding the mold and between approximately 0.127 mm (5 mils) and approximately 1,143 mm (45 thousand) after clamping. In one embodiment, the thickness of the flange is between approximately 0.635 mm and approximately 0.889 mm (between approximately 25 and 35 mils) before clamping and between approximately 0.508 and 0.762 (approximately 20-30 mils) after clamping .

Although the illustration shown in Figure 4 shows the lower part of the channel 130 leveled with the lower flange 120 of the adjacent containers, said configuration is shown for illustrative and non-limiting purposes. For example, the upper part of the channel may be level with the upper part of the flange 120, or the channel may be staggered with both the upper part and the lower part of the flange. Such configurations are intended for coverage by the scope of the present invention.

Figure 5 is an exploded top view showing the designed area of ​​fragility or channel 130 shown in Figure 3. Tearing or controlled separation between the two flanges can be facilitated by perforation. The width of the channel 134 may have a size and shape so as to allow a blade used for drilling to pierce the thickness of the channel 132. Thus, said width of the channel 134 can have a size according to the precision to which the knife or other drilling means can be precisely arranged in the channel 130, for drilling said channel 130. In one embodiment, the Channel width 134 is greater than approximately 0.508 mm (20 mils). In one embodiment, the width of the channel 134 is between approximately 0.508 mm (20 mils) and approximately 2.54 mm (100 mils). In one embodiment, the width of the channel 134 is created with the blade and comprises a width of channel 134 equal to the width of the blade that makes said channel 130.

The perforation may comprise any combination of cuts 136 and nodes 138. A cut 136 penetrates the thickness of the channel and a node 138 functions to connect both flanges 120 together. Said cuts 136 can be made in the trimming press after the containers have been formed. Referring to Figures 4 and 5, the thickness of the channel 132 can be manipulated as desired depending on several factors that include the stiffness of the material used, the ease of separation of the flanges, as well as the perforated length

or cut 136 and knot lengths 138. Similarly, cut lengths 136 and knot lengths 138 can also be adjusted as desired, in order to achieve the desired controlled tear amount. The "holding percentage" is the percentage of material that remains uncut after a material has been drilled. The determination of the optimum fastening percentage is a function of the properties of the material and the thickness of the channel 132. The exact length of the perforations 136 can be obtained by experimentation. Thus, the variables with the channel 130 that include the thickness of the channel 132 should be optimized, so that when the containers are separated from each other a tear is achieved controlled by the designed fragility line and not by the flange zone 120 of the containers.

Referring again to Figure 4, the depth of the channel can be defined as the difference between the thickness of the flange 120 and the thickness of the channel 132. In one embodiment, the width of the channel 134 is substantially the same for the depth of the Chanel. As a consequence, in one embodiment, the channel 130 has substantially a U-shape. An advantage of such a configuration is that the drilling device can intervene anywhere in the bottom of the channel 130 and the thickness of the cuts 136 will be substantially the same as the thickness of the channel 132 and not as variable as it would be in a channel in the form of V.

A V-shaped channel may not be desirable because the bottom at the apex of the V that comprises the area of ​​smaller thickness of the channel is a very narrow part. Furthermore, as the amount of material to be drilled or the thickness of the channel 132 increases when a cutting device moves away from the vertex or center of the bottom of the V-shaped channel, the ability of a consumer to tear the polypropylene to remove a container set container is more difficult. In addition, the cut lengths 138 may be more sharp with an increased channel thickness, which is not desirable for consumers who handle the separate container. However, a V-shaped channel could be useful if the accuracy of the drilling means is very high. As a consequence, in one embodiment (not shown), the channel is substantially V-shaped.

In one embodiment of the present invention, the channel 130 comprises one or more channel walls 124 where the flange 122 ends in the channel 130. In one embodiment, at least one of the channel walls 124 is substantially perpendicular 122 to the flange. In one embodiment, channel 130 is substantially perpendicular 126 to at least one wall of channel 124. In one embodiment, the channel 130 substantially comprises straight walls or walls that would be substantially parallel to the direction in which a perforated cut would be made.

Figure 6 is a perspective view showing the removal of a container from the multipack assembly shown in Figure 1. As shown in Figure 6, the first container 210 can be flexed in a

direction indicated by arrow 150, to separate the nodes 138 in order to produce a tear controlled by the channel 130, to separate the first container 210 from the second container 310. However, flexing is not required and a consumer can separate the first container 210 of the second container 310 only with tension force. Without the channel, tearing can be difficult to control and the area of ​​the flange 120 of both the first 210 and the second container 310 can be broken unnoticed and unwanted during the separation of the first container 210. Said propagation of tearing in the area of the flange or in the operculum is not desirable, since it can spoil or expose the food product to atmospheric conditions sooner than desired.

The present invention has many advantages. First, the present invention provides a method for making a multipack container detachably connected for products that can be stored, low humidity and ready for consumption. The present invention allows a multipack container with moisture barrier properties and, optionally, with oxygen barrier properties. In addition, in one embodiment, the present invention provides a multi-container container that can preserve and improve the shelf life of food and non-food items sensitive to oxygen. In addition, the present invention provides a multipack container made of material that supports a sterilization treatment. As a consequence, food products that require hot filling or sterilized applications, such as baths or dressings, including sauces and ketchup, can be packaged in accordance with the present invention. In this way, the secondary packaging typically required for polypropylene or polyolefin type packages is eliminated. In addition, food products can be provided in individual serving sizes that can be individually packaged easily with meals without requiring the opening of the food container and its arrangement in another container, such as a plastic bag.

Second, as the product is consumed, the container also disappears. As a consequence, the notion of “container disappearance” in the pantry is achieved, so the proportion of the amount of remaining packaging is in relation to the amount of food product that remains. In addition, the food product remains together and unused unlike containers connected by cardboard.

Thirdly, a multipack container can be used in a thermoforming process that results in a larger cavitation and a higher yield than is currently achieved for individual ration polypropylene products that are individually packaged together in a carton.

Fourth, the channel is broken in the area between the containers, to ensure that the operculum is punctured and / or cut more easily during the drilling stage, so that when the containers separate the operculum in the adjacent container, It tears.

As used herein, the term "package" should be understood as inclusive of any food container comprising a polyolefin sheet. Although the use of the aforementioned layers and sheets is contemplated for use in the processes for the packaging of snack foods, the multi-container can also be used for the packaging of non-food products. Although the invention has been shown and described particularly with reference to a preferred embodiment, those skilled in the art will understand it and various changes in the form and detail thereof may be made without departing from the scope of the invention, such as It is defined by the claims.