Patent Description:
In prior art there is known to use various kinds of films to wrap objects of various kinds. Depending on the intended application area, there are different restrictions and requirements placed on the films that are to be used. Laminated films comprising polymeric tapes are known, such as disclosed in <CIT>.

However, there are still problems with known solutions, for instance it could for some application areas be beneficial to achieve a film that provides a tighter sealing around an object, such as for the application area of wrapping steel coils.

It would be desirable if a film could be achieved which provides a good mechanical protection and is durable, while still wrapping tightly around the object around which it is wrapped.

<CIT> discloses a film comprising three layers, wherein the two outer layers are stretched while the middle layer is not. The stretched film layers are disposed such that the stretching directions intersect with each other and form an angle of <NUM>° to <NUM>°.

<CIT> discloses laminate sheet of at least three layers including a perforated sheet layer. Two of the layers are uniaxially molecule-oriented films. The molecular orientation may be effected in anyone of the longitudinal, lateral and oblique directions, yet it is advantageous that the axes of molecular orientation of the two films laminated on both sides of the perforated sheet are laminated to each other at angles of <NUM>° or more.

<CIT> discloses a stretchable multi-layer wrap in which two or four layers, which are provided on both sides of a plurality of ribs that are co-aligned with a longitudinal axis of the wrap.

An object of the present invention is to overcome at least some of the problems outlined above.

According to a first aspect, a film for the wrapping of objects is provided, particularly for steel coils. The film comprises a first film layer made from an elastic material, a second film layer made from a durable material, wherein the second film layer comprises a woven plastic material and is not stretched, or wherein the second film layer is pre-stretched made of polypropylene or high density or low density polyethylene, and a third layer also made from an elastic material. The first and third film layers are stretched only in a longitudinal direction, with respect to a direction the film is being fed during manufacture, wherein the first and third film layers are stretched such that they strive to go back to an un-stretched state and are stretched by <NUM>%-<NUM>%. The second layer is disposed between the first film layer and the third film layer. By having such a film with one un-stretched or pre-stretched layer with a durable material and two elastic layers that are stretched, a film is achieved that provides a good protection, while still wrapping very tightly to the object around which it is wrapped, due to the stretched material striving to go back to its un-stretched state.

According to a third aspect, there is provided a method for manufacturing a film for the wrapping of objects, comprising the steps of providing and stretching a first film layer comprising an elastic material, providing a second film layer comprising a durable material, wherein the second film layer comprises a woven plastic material and is not stretched, or wherein the second film layer is pre-stretched made of polypropylene or high density or low density polyethylene, and providing and stretching a third film layer comprising an elastic material, wherein the second film layer is provided between the first film layer and the third film layer. The method further comprises laminating the layers together to form a laminated film. The stretching is performed only in the longitudinal direction, with respect to a direction the film is being fed during manufacture, wherein the first and third film layers are stretched such that they strive to go back to an un-stretched state and wherein the elastic material is stretched by <NUM>%-<NUM>%.

By using a film, or method as disclosed herein, it is possible to achieve a film for the wrapping of objects that provides a good protection, both mechanically and against external factors such as air and moisture, while still wrapping very tightly around the object to be wrapped.

In the following, a detailed description of the different embodiments of the solution is disclosed with reference to the accompanying drawings. All examples herein should be seen as part of the general description and are therefore possible to combine in any way in general terms. Individual features of the various embodiments and methods may be combined or exchanged unless such combination or exchange is clearly contradictory to the overall function of the implementation.

Briefly described, the solution relates to a film for the wrapping of objects, as well as a method for the wrapping of objects. The solution is primarily intended to be used for wrapping steel coils and other similar materials, but it should be understood that the solution may be applicable to other types of materials as well.

The solution is intended to achieve a film that protects the wrapped object from external forces, such as moisture, air and scraping, and that tightly wraps around the object it is intended to protect.

This is achieved by having a film comprising at least three layers, wherein one layer is stretched (or pre-stretched) while the other two layers are not. By stretching one layer and not the other, it is possible to use more rigid, sturdy and durable materials for the protective layer that provide a better mechanical protection and reinforcing properties than materials that are adapted for being stretched. Further, by stretching one of the layers, it is possible to achieve a film that strives to go back to un-stretched state, which makes the film wrap more tightly around the object it is intended to protect. This disclosure also relates to a method for manufacturing such a film as well. The solution will now be described in further detail with reference to the accompanying drawings. <FIG> shows a film <NUM> according to the present disclosure comprising two layers, a first layer <NUM> and a second layer <NUM>. The first layers <NUM> is stretched, such that it strives to go back to its original un-stretched state. This entails that the film will wrap more tightly around an object than if no layers were stretched. Meanwhile, the second layer <NUM> is not stretched, which entails that a sturdier and more rigid material may be used, which provides better mechanical protection than materials that are adapted to be stretched.

The first layer <NUM> typically comprises an elastomer, such a low density polyethylene. The material of the first layer <NUM> is intended to be flexible while still providing a good protection against external factors, such as e.g. moisture in the air. As mentioned, the first layer <NUM> of the film is stretched. Typically this is done during the manufacturing of the film, which will be described in more detail later in this disclosure. The film is typically only stretched in one direction, which is the same direction as the film is being fed during manufacture, which in a completed film would be seen as the longitudinal direction.

The second layer <NUM> typically comprises a woven plastic material. The second layer <NUM> is intended to provide mechanical protection, and therefore it is sturdier, stronger and more rigid than the first layer <NUM>. Also, unlike the first layer <NUM>, the second layer <NUM> is not stretched, which enables the previously mentioned use of a material that is sturdier, stronger and more rigid.

The second layer may in some embodiments be made of polypropylene. In other embodiments, the second layer may be made from polyethylene, both high density and low density, that has been pre-stretched, which results in it being much less elastic, more durable and provides a better mechanical protection than polyethylene that has not been pre-stretched. In embodiments wherein the second layer comprises polypropylene, the polypropylene may also be pre-stretched.

The first layer <NUM> and the middle layer <NUM> are laminated together to form one film comprising two layers. Such a film will have the mechanical protection provided by the second layer <NUM>, comprising a sturdy and durable material, while still wrapping very tightly around the object to be wrapped due to the first layer <NUM> being stretched, which makes it strive to go back to its un-stretched state. The sturdy material may for instance be a woven plastic material. The elastic material is typically an elastomer, such as low density polyethylene. It should be understood that the examples used herein are not to be limiting, it is possible to use other materials that have similar properties as the examples above.

The film according to the present disclosure is typically intended for the wrapping of steel coils. Steel coils have very sharp edges, and the weight entails that the contact pressure is very high when they are lifted, which requires a film that is both durable and flexible, which may be achieved as disclosed herein.

In some embodiments, the film <NUM> comprises three layers instead of two. This is shown in <FIG>. In this embodiment, the film comprises two outer layers <NUM> made from an elastic material, and a middle layer <NUM> made from a sturdy material. By using one elastic layer on each side of the sturdy layer, the advantageous properties of the film are further enhanced, such that it gives a better protection and wraps tighter around the objects intended to be wrapped.

Looking now at <FIG>, a system for manufacturing a film will now be described. <FIG> shows a system <NUM> comprising a first roller <NUM> and a second roller <NUM>. The first <NUM> and second <NUM> rollers are positioned at a first position in the production cycle, which is upstream from a second position where laminating rollers <NUM> are positioned. The laminating rollers <NUM> are adapted to laminate the layers of film together into one film comprising two or more layer. This may be done e.g. through pressing the materials together extremely tightly, using adhesive agents and/or heat, and other similar laminating technologies aimed at joining multiple layers of materials together.

The first roller <NUM> is adapted to feed a first film layer comprising an elastic material, and the second roller <NUM> is adapted to feed a second film layer comprising a sturdy material. The first roller <NUM> is adapted to run at a speed v1. The second roller <NUM> is adapted to run at a speed higher than that of the first roller <NUM>, shown as v2. The laminating rollers <NUM> are also adapted to run at the second speed v2.

The speed with which the materials are fed towards the laminating rollers <NUM> is constant for each material, even though the speed of individual rollers may differ. The speed with which the films is fed by the laminating rollers <NUM> is also constant. Depending on the exact structure of the system, this may entail slight variations in how rollers are configured. If the rollers comprise a stack of material which is wound around an axis and the unwound as the material is fed, the rotational speed of the roller would have to continuously increase slightly to maintain a constant feeding speed, as the diameter of the wound material decreases due to the material being fed towards the laminating rollers <NUM>.

Due to the speed of the rollers differing, the first layer of the film will be stretched but second layer will not be. Since the first roller <NUM> feeds its material towards the laminating rollers <NUM> at a first speed v1, while the laminating rollers <NUM> feeds the film in the feeding direction at a second speed v2, wherein v2 is higher than v1, the elastic material will be stretched. This is due to the difference in speeds that occurs at the second position, i.e. at the laminating rollers <NUM>. Since the feeding speed of the laminating rollers <NUM> is higher than the feeding speed of the first roller <NUM>, the material will be stretched at the second position. As for the second roller <NUM>, the sturdy material being fed by the second roller <NUM> is not stretched, since the feeding speed of the second roller <NUM> is the same as the feeding speed of the laminating rollers <NUM>, i.e. v2.

The second roller <NUM>, however, operates at the same speed as the laminating rollers <NUM>, which entails that the sturdy layer of the film, which is the one fed by the second roller <NUM>, is not stretched during the manufacturing process. Typically, the system is adapted such that the elastic material is stretched by an additional <NUM>-<NUM>% as compared to its original state, but in some embodiments it may be higher, such as up to <NUM>%. Optionally, the system <NUM> may also comprise a coil <NUM> onto which the film may be wound.

In some embodiments, the system <NUM> comprises three rollers instead of two. This is shown in <FIG>. In this embodiment, the system further comprises a third roller <NUM>. Typically, the third roller <NUM> is positioned such that the second roller <NUM> is disposed between the first roller <NUM> and the third roller <NUM>. The third roller <NUM> is, like the first roller <NUM>, adapted to feed a film layer comprising an elastic material. The third roller <NUM> runs at a speed v1, same as the first roller <NUM>, which results in that the film layer fed by the third roller <NUM> is stretched in the same way that the film layer fed by the first roller <NUM> is. This results in a film comprising three layers, wherein the two outer layers are stretched and comprise an elastic material, while the middle layer comprises a sturdy material. The layers that are stretched are typically stretched in the same direction as the film is being fed, which is the longitudinal direction of the resulting film.

Looking now at <FIG>, the method according to the present disclosure will be described. The first step S100 comprises providing and stretching a first film layer, typically comprising an elastomeric material such as low density polyethylene. By stretching the material, it strives to go back to its un-stretched state, which results in the material wrapping very tightly around the object around which it is wrapped.

The second step S110 comprises providing a second film layer, the second film layer comprising a sturdy material such as woven plastic material.

The final step S130 of the method comprises laminating the layers together to form one film comprising two layers, wherein the first layers is stretched and the second layer is not.

In some embodiments, the method further comprises a step S120 of providing and stretching a third film layer, the third film layer also comprising an elastic material. This step may be seen in <FIG>. In this embodiment, the second film layer is typically provided between the first film layer and the third film layer, and the step of laminating the layers comprises laminating three layers instead of two.

Claim 1:
A film (<NUM>) for the wrapping of objects, comprising:
a first film layer (<NUM>) made from an elastic material;
a second film layer (<NUM>) made from a durable material, wherein the second film layer (<NUM>) comprises a woven plastic material and is not stretched, or wherein the second film layer (<NUM>) is pre-stretched made of polypropylene or high density or low density polyethylene;
a third film layer (<NUM>) made from an elastic material, wherein the second film layer (<NUM>) is disposed between the first film layer (<NUM>) and the third film layer (<NUM>), wherein the first film layer (<NUM>) and the third film layer (<NUM>) are stretched only in a longitudinal direction, with respect to a direction the film is being fed during manufacture, wherein the first and third layers are stretched such that they strive to go back to an un-stretched state and are stretched by <NUM>%-<NUM>%.