DE1173811B - Containers made from thermoplastics - Google Patents

Description

Thermoplastic containers. Thermoplastic plastics are already widely used to make cans and containers. Most of time these are closed with screw caps, snap locks or hold-up lids. It has also been proposed to glue or weld the lid and the can. This gives an absolutely tight seal, as it is for many areas of application is required. Opening cans with thicker walls is difficult.

So far, no way is known to easily and without the doses special tools to open.

Of course it is possible to cut the welded edge with a knife or a pair of scissors, but especially with the strength of the polyolefins considerable force is required to do this, and the risk of injury is great.

It is known to insert a wire into the weld seam that passes through Heating causes the welding or opening, but inserted through this Wire, which has to emerge from the material, becomes the absolutely tight weld, the z. B. is absolutely necessary for canned food, very difficult, if not impossible, above all because the bond between plastic and metal is poor and with the sterilization makes the different expansion coefficient noticeable. In addition, it is difficult for a housewife to open such a can.

It has also been suggested to insert a pull-wire into a Insert the groove in the can or lid. But here too the end of the wire has to be protrude from the can, and the difficulties outlined above occur.

To remedy these difficulties, according to the invention, for containers, preferably cans with a welded-on lid made of thermoplastic plastics in one by opposing circumferential grooves in the can and lid edge formed ring recess, which lies within the welding lips of the lid and can, a correspondingly bent upright band is provided, which when used acts as a cutting tool or snap ring from external, axially directed forces.

In addition to metal, the most suitable material for this tape is above all Polypropylene due to its hardness and its high softening point.

It has been shown that a can made of polyethylene when used a little more force can also be opened with the help of a polyethylene tape, like this that it is possible to make tape and cover out of the same To manufacture material. One can As a result, the tape is also molded on during the manufacture of the cover and thus save the subsequent insertion of a tape.

For the consumer it is only necessary to use a hammer, a meat tenderizer, cutting board, or other kitchen or household appliance all around to the circumferential elevation of the lid, under which the tape is located hit, which shears the edge of the can, so that the lid with the welded can edge can be removed. The edge is cut off so smooth that no sharp protruding edges remain and the can is a pleasing one Appearance, so that e.g. tin cans can be used directly at the table. If not all items are removed at once, the can can be removed by putting on the Lid must be tightly closed again.

When using a metal band, the different coefficient of thermal expansion plays a role does not matter, as the metal band is neither firmly connected to the plastic nor is it ring-shaped is self-contained so that it can expand or contract within the groove can.

As a material for the containers, preferably cans, are practically suitable all thermoplastics.

The same ones are suitable for the production of the tapes to be inserted Plastics, but the tape must always have at least the same hardness as the can.

In addition to being used as cans for food, those according to the invention are also suitable Containers are also particularly good for packing other filling goods that are after to be sterilized after filling, e.g. B. for bandages, medical devices or medication, especially for packs that are not for one instant Consumption are intended, but should only be stored for an emergency, like bandages for first aid. The packs are so stable that they are very rough can be handled.

Airplanes can be dropped without further ado, only then Of course, care must be taken to ensure that the circumferential elevation in the lid on impact is not charged. However, this can be converted into larger ones by packing them up appropriately Bins can be easily reached.

The all-round increase in the lid also has a very good effect The cans can be stacked as they can be placed in the lid and this prevents them from slipping. The stackability can be made by appropriate shape can still be supported by the bottom of the can and the lid and is a great advantage for storage and shipping.

Preferably the lid is shaped to fit something into the can protrudes so that the content does not come into contact with the tape. This can be done by an inner flange or by pulling down the bottom of the lid. One Such a shape of the lid also causes a particularly tight fit of the same the bursting of the edge of the can. In the case of aggressive filling goods, it will be advantageous to Use a tin-plated metal band if a plastic band is not preferred. In the case of very hard plastics, it may be necessary to make the bottom of the groove a little thinner to be carried out as the other walls or, instead of a simple metal bath, a punching knife to be inserted into the groove.

It has a particular advantage that the tape to be inserted is so is cheap that the can is only slightly more expensive by this, while the Opening process is made much easier.

The invention is to be explained by way of example through the drawing, without any intention that it should be restricted to this particular form.

F i g. 1 shows an overall view and FIG. 2 is a partial view of a welded round box.

Lid 3 and can 2 are injection molded from linear polyethylene one Density of 0.95 and a crystallite melting point of 127 to 123C C. Inner half of the welding lips l can 2 and lid 3 each have a groove 4 and 5, respectively are opposite one another and have an annular recess for receiving the band 6 form. The cover is also provided with an inner flange 7, which is somewhat in the can protrudes and closes off the filling space from the groove 5. Can bottom and lid are matched to one another to achieve good stackability.

The tape used is about 0.7 mm thick and about 7 mm wide. To After welding, the can is absolutely tightly closed and can be opened without bursting sterilize the seam. A blunt object is used to open different parts Set struck on the groove 4 upwardly limiting elevation of the lid. At the bottom 8 of the groove 5, the cans edge loosens quite smoothly from the can jacket and can lifted off with the lid. The opened can has a pleasing appearance and can be tightly closed again by placing the lid on.

The band can not only be rounded for cans, but also oval, square or any other cross-section and also with larger ones Use packaging containers. It is only necessary to make the tape the shape of the circumferential Adjust groove.

Claims (2)

Claims: 1. Container, preferably can, with welded-on Lid made of thermoplastics, characterized in that in one formed by opposing circumferential grooves in the can and lid edge Ring recess, which lies within the welding lips of the lid and can, a corresponding bent, edgewise band is located, which when using outer, axially directed forces acts as a cutting tool or snap ring. 2. Container according to claim 1, characterized in that the tape consists of the same plastic as the lid and is molded onto it.