Method for producing multilayer plastics straps, and multilayer plastics strap

Abstract

The invention relates to a method for producing multilayer plastics straps, and to a multilayer plastics strap. The method comprises providing a first and a second plastics material, melting same and combining the two plastics melts, forming a multilayer film strand, splitting the film strand before or after a method step of drawing. The first plastics material is prepared with a proportion of 50% by weight to 100% by weight of exclusively mechanically recycled plastics material. The multilayer film strand is formed in such a way that it consists of 50% by weight to 95% by weight of the first plastics material and 5% by weight to 50% by weight of the second plastics material. The multilayer plastics strap consists of a base layer made of the first plastics material and of surface layers, joined to a top side and to an underside of this base layer, made of a second plastics material.

Description

[0001] METHOD FOR PRODUCING MULTI-LAYER PLASTIC STRAPPING BANDS AND MULTI-LAYER PLASTIC STRAPPING BAND

[0002] The invention relates to a method for producing multi-layer plastic strapping bands and a multi-layer plastic strapping band.

[0003] Plastic strapping is primarily used to secure goods or to securely hold goods. The goods to be secured are wrapped around the strapping, tensioned, and the strap ends are usually joined together, for example, by welding. Plastic strapping offers numerous advantages over strapping made of other materials, such as steel. For example, plastic strapping is simpler and cheaper to produce, easier to handle, corrosion-free, and also has a low carbon footprint. Such strapping, their intended use, and their properties are generally specified, for example, in EN 13394 or in national standards corresponding to this European standard, such as ÖNORM EN 13394.

[0004] Thermoplastics are used to manufacture plastic strapping. The high tensile strength required for the intended application is achieved by monoaxial stretching using so-called stretching machines. This type of stretching induces an orientation of the macromolecule chains in the stretching direction, or longitudinal direction, in the plastic strapping, thereby achieving the high tensile strengths of the plastic materials in this direction. Especially with semi-crystalline, thermoplastic materials, this can achieve tensile strengths similar to those of steel.

[0005] The methods for manufacturing and using plastic strapping have generally been known for a long time. A summary of such methods is described, for example, in DE 4007 560 A1. More recent approaches often aim to improve the properties of the actual strapping process, such as better handling during (mechanical) looping, better connectability or weldability, and the like. Another aspect also concerns manufacturing costs, and in particular material costs. According to common practice, high-quality plastic materials are used, since the required high tensile and tear strength of the strapping requires good properties from the plastic materials, such as sufficiently high average molecular weights and molecular mass distributions. Therefore, new plastic materials are often used to manufacture plastic strapping.

[0006] But the use of recycled plastic material is also generally known. For example, strapping made from polycondensates, especially polyester strapping, does indeed use recycled materials. These recycled polycondensates are often subjected to chemical solid- or liquid-phase polycondensation, usually under reduced pressure or vacuum, prior to being processed into strapping. Such upstream polycondensation can increase the molecular weight or the so-called intrinsic viscosity (iV) of the polycondensates, which is why recycled polycondensate plastic material exhibits very good properties. It is known that the properties of such recycled polycondensates can even be better than those of freshly polymerized polycondensates.

[0007] Multilayer plastic strapping bands and their production have also been described, for example in DE 28 16 044 A1 and EP 2 954 999 A1. DE 28 16 044 A1 discloses multilayer bands with a base layer and at least one surface layer connected thereto, wherein the polymer of the surface layer is said to have a higher structural viscosity or a higher molecular weight than the polymer of the base layer. EP 2 954 999 A1 teaches, in particular, the use of expensive polyester in a core layer, wherein the core layer is encased in so-called functional layers, in which functional layers plastic material, which may not be polyester and would therefore be less expensive, can also be used. These functional layers can also comprise additives, by means of which additives are said to achieve certain functional properties.

[0008] Even in view of the current state of the art, there is still a need for improvement with regard to the most sustainable and cost-efficient production of plastic strapping bands or corresponding plastic strapping bands.

[0009] The object of the present invention was to remedy the remaining deficiencies of the prior art and to provide a plastic strapping band which can be produced sustainably and cost-efficiently and yet has the necessary mechanical properties for use as a strapping band, as well as to provide a corresponding method for producing such a plastic strapping band.

[0010] This object is achieved by a method for producing a multi-layer plastic strapping band and a multi-layer plastic strapping band according to the claims.

[0011] The process for producing multi-layer plastic strapping includes:

[0012] - Providing a first plastic material consisting of 70 wt.% to 100 wt.% of a thermoplastic first polymer and 0 wt.% to 30 wt.% of another component or several other components, and providing a second plastic material consisting of 90 wt.% to 100 wt.% of a second semi-crystalline thermoplastic polymer and 0 wt.% to 10 wt.% of another component or several other components,

[0013] - melting the first plastic material by means of an extrusion device to form a first plastic melt and melting the second plastic material by means of a further extrusion device to form a second plastic melt,

[0014] - Combining the first plastic melt and the second plastic melt such that the second plastic melt completely covers a top and a bottom of the first plastic melt,

[0015] - forming a multilayer film strand by feeding the first plastic melt and the second plastic melt in a material transport direction to a forming device, and cooling the first plastic material and the second plastic material, so that a base strand layer and a surface strand layer of the multilayer film strand connected to an upper side and a lower side of this base strand layer are formed,

[0016] - Dividing or cutting the multi-layer film strand along the material transport direction into multi-layer tape strands by means of cutting devices,

[0017] - Stretching in the material transport direction of the multilayer film strand or the multilayer tape strands by means of a stretching device.

[0018] The first plastic material is provided with a proportion of 50 wt.% to 100 wt.% of exclusively mechanically recycled plastic material. The multilayer film strand is formed such that it consists of 50 wt.% to 95 wt.% of the first plastic material and 5 wt.% to 50 wt.% of the second plastic material.

[0019] At this point it should be noted that, even if the method according to the invention is described in a specific order, this order is not mandatory and the sequence of the individual method steps can be interchanged as long as this is technically reasonable and possible. For example, the method step of cutting the multilayer film strand can take place before or after stretching the multilayer film strand. It is also possible and not excluded to carry out intermediate steps, including intermediate steps not explicitly described here, between the individual method steps specified. Some of the method steps must, of course, be carried out in a specific order for technical reasons or due to the feature definitions in the claims. For example, the melting of the first and second plastic materials must, of course, be carried out before forming the multilayer film strand.The material transport direction mentioned can, as is well known, also be referred to as machine direction (MD) or is synonymous with this.

[0020] The process can be used in particular for the production of multi-layer plastic strapping as specified in (ÖNORM) EN 13394 or in accordance with (ÖNORM) EN 13394. The process can therefore be used for the production of multi-layer plastic strapping with a tensile strength of at least 300 N / mm 2 be provided.

[0021] As the first plastic material, in particular, a plastic material consisting of 70 wt.% to 98 wt.% thermoplastic, first polymer and 2 wt.% to 30 wt.% of one or more further components can be provided. Regardless of the amount of the further component(s) of the first plastic material, this / these further component(s) of the first plastic material can be formed, for example, by fillers, additives, plasticizers, or by one or more polymer(s) other than the first polymer.

[0022] In this context, the first plastic material can, for example, be a plastic material with a proportion of foreign polymer, i.e. a different polymer than the first thermoplastic polymer. For example, the proportion of foreign polymer can be from 2 wt.% to 30 wt.%. The foreign polymer can certainly comprise a layer-forming gas or liquid barrier plastic and / or a copolymer. However, the first plastic material 1 can also be a plastic material with a proportion of inorganic fillers, for example a proportion of inorganic fillers of 2 wt.% to 30 wt.%, in particular 5 wt.% to 30 wt.%. The inorganic filler can, for example, be formed by chalk, talc or a mixture thereof.Independently of this or additionally, a plastic material can be provided which comprises solid particles with a particle size of up to 500 pm, in particular 150 pm to 500 pm. Accordingly, the first plastic material can be filtered or have been filtered by means of a filter device with a mesh size of 500 pm during melting, or during a melting process preceding the present method. A plastic material comprising dyes, such as printing inks, for example in a proportion of 2 wt.% to 30 wt.%, can also be provided as the first plastic material. Preferably, a post-consumer recycling (PCR) plastic material can be provided as the first plastic material. A plastic material can also be provided which, during melting orProcessing temperature during the melting of the first plastic material includes non-melting components.

[0023] In addition to the exclusively mechanically recycled plastic material, the first plastic material can also comprise up to 50 wt.% non-recycled or chemically recycled plastic material. Preferably, the first plastic material can be provided with a proportion of 80 wt.% to 100 wt.% exclusively mechanically recycled plastic material and additionally up to 20 wt.% non-recycled or chemically recycled plastic material. Regardless of the type of production or processing or the type of provision of the components for the first plastic material, the first plastic material, as specified in the claims, consists of 70 wt.% to 100 wt.% of the thermoplastic, first polymer and 0 wt.% to 30 wt.% of the further component or components. The thermoplastic, first polymer can be formed, for example, from polyethylene terephthalate, polypropylene, polyethylene, polyamide, or polystyrene.In particular, the first plastic material can be a plastic material that consists entirely of mechanically recycled plastic material. The second plastic material can be a non-recycled or chemically recycled plastic material, or else a high-quality, mechanically recycled plastic material, in particular a mechanically recycled post-industrial recycled plastic material. The same applies to the second plastic material: regardless of the amount of the further component(s) of the second plastic material, this or these further components of the second plastic material can be formed, for example, by fillers, additives, plasticizers, or by one or more other poly€€ other than the second, semi-crystalline polymer.

[0024] Unlike the first plastic material, the second plastic material can be a plastic material that does not contain any printing inks, any layer-forming gas or liquid barrier plastic, or any components that do not melt at a melting or processing temperature during the melting of the second plastic material, such as metals, wood fillers, glass (fibers), or polymers that melt at temperatures higher than the melting or processing temperature. Furthermore, the second plastic material can be a plastic material that contains a maximum proportion of 10% by weight, preferably a maximum of 5% by weight, of inorganic filler, such as chalk or talc, or also, for example, dyes for coloring plastic materials, such as masterbatch dyes.The second plastic material can be a plastic material comprising solid particles with a particle size of up to 150 pm. Accordingly, the second plastic material can be filtered or have been filtered during the melting process, or during a melting process preceding the present method, using a filter device with a mesh size of 150 pm.

[0025] An exclusively mechanically recycled plastic material is understood to be a plastic material that has already been used or employed at least once and in which no chemical recycling, in particular no deliberate chemical reaction, was carried out during the recycling process. As is well known, chemical recycling can occur through chain scission or depolymerization of polymers down to monomers and subsequent re-polymerization. In particular, the first plastic material can be post-consumer and / or post-industrial goods or plastic material. A chemically recycled plastic material is accordingly understood to be a plastic material in which such chemical reactions were deliberately induced during the recycling process, in particular depolymerization and subsequent re-polymerization. A non-recycled plastic material is understood to be a freshly polymerized ormanufactured plastic material which has not yet been used, i.e. a new plastic material or new product.

[0026] The cooling of the multilayer film strand can be carried out exclusively by means of the forming device itself. For this purpose, the first and second plastic melts can be cooled after they have been combined, for example, by means of at least one temperature-controlled roller or roller with a temperature-controlled roller surface of the forming device. For example, at least one roller of the forming device can be subjected to a coolant. In addition, however, the plastic melts can also be cooled separately before forming the multilayer film strand and / or an additional, separate cooling of the film strand after forming the film strand can be carried out by means of an additional cooling device, such as a water bath.The film thickness of the multilayer film strand can be specifically adjusted, for example, as is known per se, by passing the combined plastic melts through a gap between adjacent rollers of the forming device, whereby at least one of the adjacent rollers can be arranged to be adjustable to vary the film thickness. The forming device can be formed, as is known per se, by a rolling mill, also referred to as a calender or smoothing unit.

[0027] The multilayer film strand can be cut, for example, using knife blades, non-rotatable or circular blades that can rotate along or against the direction of material transport, or even using cutting devices designed as lasers or water jets. As already mentioned, this cutting of the film strand can generally take place before or after stretching.

[0028] A thickness of the multilayer film strand after forming can be set, for example, to 0.6 mm to 3.8 mm, preferably 0.8 mm to 2.8 mm. By stretching, a thickness of the multilayer tape strands or, if appropriate, a thickness of the multilayer film strand can be set or reduced to a value of 0.15 mm to 1.8 mm, preferably 0.2 mm to 1.4 mm. A width of the multilayer tape strands after stretching and cutting can be set to a value of 3 mm to 40 mm, in particular 4 mm to 36 mm, wherein the width of the stretched, multilayer tape strands can be selected primarily according to the intended use for the multilayer plastic strapping.

[0029] The specified manufacturing process allows plastic strapping to be produced more sustainably and cost-efficiently than before. This is primarily due to the use of a large amount of cost-effectively and sustainably produced or supplied, exclusively mechanically recycled plastic material to form the first plastic material or the base strand layer.

[0030] Surprisingly, it has been proven that such exclusively mechanically recycled plastic material can be processed sufficiently well into multi-layer plastic strapping and that the plastic strapping produced according to the process also have sufficiently good properties for use as strapping. Without wishing to be bound by any theory, it is assumed that the surface layers made of the second plastic material that are connected to the base strand layer are able to sufficiently stabilize the entire layer structure, particularly during the stretching step, which is subject to great mechanical stress and is therefore critical to the process. Surprisingly, the relatively small amount of second plastic material of 5 wt.% to 50 wt.% is entirely sufficient for this. The multi-layer film strand can preferably be shaped in such a way that it consists of 55 wt.% to 90 wt.% of the first plastic material and 10 wt.% to 45 wt.% of the second plastic material.

[0031] The first plastic material or the base strand layer can also contain considerable amounts of component(s) that are not thermoplastic polymers. For example, it has been shown that even plastic materials with a high filler content of up to 30% by weight, and therefore not considered materially recyclable, can be processed into multi-layer plastic strapping using the specified process, and can therefore be materially recycled or reused. The first plastic material can even contain ground material or agglomerates, for example, or even be formed from ground material. In particular, it has been shown that the stretching process or stretching step can certainly be accomplished, at least in conjunction with the stabilizing effect of the surface layer bonded to the base strand layer.Common stretching ratios of 1:4 to 1:20 can be used for the stretching process step.

[0032] Following the stretching process, further processing steps can optionally be performed. As is well known, a stretched strapping strand can be embossed, waxed, printed, or otherwise treated. Finally, the multi-layer strapping strands can, of course, be assembled. Typically, the resulting strapping strands are wound onto spools as so-called continuous strands for assembly and cut into ready-to-use strapping bands of the appropriate or required length at the point of use.

[0033] In a further development of the method, it can be provided that a plastic material with a melt mass flow rate (MFR) according to ISO 1133 of 2 g / 10 min to 35 g / 10 min is provided as the first plastic material, and that a plastic material with a melt mass flow rate (MFR) according to ISO 1133 that is the same or greater than the first plastic material is provided as the second plastic material.

[0034] This process allows for a stable formation of the multilayer film strand with a homogeneous, regular, or even uniform layer formation. In particular, irregularities in layer formation can be prevented.

[0035] In principle, the first, thermoplastic polymer and the second, semi-crystalline, thermoplastic polymer can each be formed by any polymers.

[0036] Preferably, however, the method can provide for the provision of plastic materials of the same type as the first plastic material and the second plastic material.

[0037] This measure, in particular, makes it possible to produce a film strand with a stable and permanently uniform layer structure, as well as improved adhesion between the base strand layer and the surface strand layers. Similar plastic materials are understood to be plastic materials that comprise the same type of thermoplastic polymer. Thus, in this embodiment, both the first and second plastic materials can comprise thermoplastic polymers, for example, a polyolefin, a polyester, or a polyamide as the first and second polymers, respectively.

[0038] In particular, it can be provided that plastic materials are provided as the first plastic material and as the second plastic material in which a chemical molecular formula of the thermoplastic, first polymer corresponds to a chemical molecular formula of the semi-crystalline thermoplastic, second polymer.

[0039] By carrying out this process, the adhesion of the surface strand layers to the base strand layer can be further improved during the formation of the multi-layer film strand as well as during stretching, but also subsequently during the use of the multi-layer plastic strapping bands.

[0040] An embodiment of the method may be particularly useful in which plastic materials are provided as the first plastic material and as the second plastic material, in which both the thermoplastic, first polymer and the semi-crystalline, thermoplastic, second polymer are formed by polypropylene.

[0041] Plastic materials based on polypropylene have proven particularly suitable for the formation of multi-layer plastic strapping.

[0042] As the first plastic material, for example, a plastic material with a content of 2 wt.% to 30 wt.% of fillers can be provided in the process.

[0043] This can reduce the manufacturing costs of multi-layer plastic strapping in particular, since a plastic material with a high proportion of filler(s) is generally cheaper to provide.

[0044] In particular, the first plastic material provided may be a plastic material containing 2 wt.% to 30 wt.% of coloring filler(s).

[0045] Such fillers can be present in the first plastic material as particularly cost-effective materials. Nevertheless, for example, the multilayered, stretched ribbon strands, in particular, can be printed on a surface strand layer or layers after stretching, since a surface strand layer can act as a cover layer over a base strand layer connected to it, thus providing good coverage for coloring of the base layer.

[0046] In a particularly preferred embodiment of the method, it can be provided that the multilayer film strand is divided into multilayer tape strands by means of the cutting devices after forming and before stretching.

[0047] By cutting the multi-layer film strand before stretching, the cutting or dicing process can be carried out very gently and with very little wear and abrasion. This is because the film strand is still at a high temperature and relatively soft at this point in the process. This relatively high temperature is also necessary for the subsequent stretching step. In this context, it has nevertheless been proven that, despite the film strand still being soft, very precise cutting of the multi-layer film strand is possible using conventional cutting or dicing devices, and there are hardly any deviations in the respective strip strand widths of the cut, unstretched strip strands. Furthermore, with this type of process, multi-layer, stretched strip strands with very uniform strip strand widths and strip strand thicknesses can be produced even after stretching.This is despite the significant deformation inherent in the stretching of the multilayer, divided tape strands following the slitting step. Slitting before the stretching step is particularly advantageous when forming multilayer film or tape strands, as, unlike slitting after stretching, tendencies toward delamination can be prevented.

[0048] When cutting the film strand before stretching, it has also proven advantageous if the multi-layer film strand is cooled to a temperature of 75 °C to 135 °C for the cutting process step.

[0049] Below the specified temperature range, increased wear on the cutting devices can occur with some plastic materials, particularly with cutting devices in the form of cutting tools. Above the specified temperature range, increased material flow of the plastic material can lead, for example, to re-sticking of the multilayer, undrawn strip strands, as well as to the formation of multilayer, undrawn strip strands with inhomogeneous strip strand widths and thicknesses, especially in the edge areas of the multilayer strip strands. In particular, the multilayer film strand can be cooled to a temperature of 80 °C to 130 °C for the cutting process step.

[0050] Furthermore, the method can provide for the forming of the multilayer film strand by means of a forming device comprising rotatably mounted rollers. In particular, the forming device can be formed by a so-called rolling mill, also referred to as a calender or smoothing mill. As already mentioned, the forming of the film strand can be carried out by means of such rollers, wherein a film thickness of the multilayer film strand can be specifically adjusted, for example, by passing the first plastic melt through a gap between adjacent rollers. In this case, at least one of the adjacent rollers can be arranged to be adjustable in order to vary the film thickness.Shaping devices comprising rollers have proven particularly suitable for the present process for forming film strands with a very uniform and even structure and very evenly designed surfaces on the top and bottom.

[0051] In this context, it can also be expedient if, during the process step of forming the film strand, at least one surface of the multi-layer film strand is structured by means of at least one structured roller surface. Such a surface structure on at least one surface can be particularly helpful when using the plastic strapping bands to form a strap. For example, such a surface structure can support or simplify the conventionally carried out welding process. In particular, such a surface structure can make a so-called friction welding process considerably easier or more efficient. For example, the at least one surface of the multi-layer film strand can be provided with a microstructure, in particular with a microstructure that is not visible to the naked eye, in the sense of a matting.Of course, a familiar embossing pattern, visible to the naked eye, such as a conventional diamond pattern, is also possible. Alternatively, for certain applications, it may be advantageous to make the surfaces of the multilayer film strand very smooth, i.e., smooth them using at least one roller surface.

[0052] If the multilayer film strand is divided before stretching, it can further be provided that at least some of the cutting devices for adjusting the strip strand widths of the multilayer, unstretched strip strands are adjusted along the direction running parallel to the strip strand widths. Such a process allows for simple but efficient setting of the desired strip strand widths of the multilayer, unstretched strip strands and, in conjunction with the subsequent stretching, therefore also for targeted setting of the desired strip strand widths of the multilayer, stretched strip strands or the ultimately resulting plastic strapping bands. In particular, all existing cutting devices for adjusting the strip strand widths of the multilayer, unstretched strip strands can be adjusted along the direction running parallel to the strip strand widths.In addition, in connection with the adjustment along the strip strand widths, it can also be provided that at least some of the cutting devices are adjusted away from the multi-layer film strand or the multi-layer, unstretched strip strands.

[0053] Furthermore, in connection with the adjustment of the cutting devices, it may also be useful for actual values ​​of the strip strand widths of the multi-layer, stretched strip strands to be recorded by means of at least one sensor device following the stretching process. Based on these determined actual values, the cutting devices are adjusted with regard to the respective desired target values ​​for the strip strand widths of the multi-layer, stretched strip strands along the direction running parallel to the strip strand widths in order to adjust the strip strand widths of the multi-layer, undrawn strip strands. This measure allows simple and variable adjustment of the respective desired strip strand widths for both the undrawn and the stretched strip strands and thus provides particularly flexible process control. The at least one sensor device can be formed specifically by an optical sensor, in particular a camera.

[0054] To automate the adjustment of the cutting devices along the direction of the strip strand widths, it may be expedient for the recorded actual values ​​of the strip strand widths of the multi-layer, stretched strip strands to be transmitted from the sensor device to a control device, and for the cutting devices to be automatically adjusted along the direction parallel to the strip strand widths by the control device to adjust the strip strand widths of the multi-layer, undrawn strip strands. This allows for a high degree of process automation.Irrespective of this, a method variant may also be advantageous in which, following the stretching process, actual values ​​of the strip strand thicknesses of the multi-layer, stretched strip strands are recorded by means of at least one sensor device, and in which a film strand thickness of the multi-layer film strand is adjusted by means of the shaping device with regard to the respective desired target values ​​for the strip strand thicknesses of the multi-layer, stretched strip strands. This measure specifically allows for simple and variable adjustment of the respective desired strip strand thicknesses of the multi-layer, stretched strip strands. The at least one sensor device can in turn be formed by an optical sensor, in particular a camera. In this case, the same sensor device can essentially be used which is also used to determine the strip strand widths of the stretched strip strands, or, of course, a separate sensor device.

[0055] In connection with the determination of the strip thicknesses of the multi-layer, stretched strip strands, it can again be provided that the recorded actual values ​​of the strip thicknesses of these stretched strip strands are transmitted from the sensor device to a control device, and the film strand thickness is adjusted automatically by controlling the forming device via the control device. This measure also allows for a highly automated process.

[0056] The object of the invention is also achieved by a multi-layer plastic strapping band. The plastic strapping band can be produced, in particular, according to or with the method described above.

[0057] The multi-layer plastic strapping consists of a base layer made of a first plastic material and surface layers made of a second plastic material connected to a top and a bottom of this base layer. The first plastic material is formed from 70 wt.% to 100 wt.% thermoplastic, first polymer and 0 wt.% to 30 wt.% of one or more further components. The second plastic material is formed from 90 wt.% to 100 wt.% semi-crystalline, thermoplastic second polymer and 0 wt.% to 10 wt.% of one or more further components. Furthermore, the first plastic material has a proportion of 50 wt.% to 100 wt.% of exclusively mechanically recycled plastic material. The multi-layer plastic strapping consists of 50 wt.% to 95 wt.% of the first plastic material and 5 wt.% to 50 wt.% of the second plastic material.

[0058] The multi-layer plastic strapping can be a strapping as specified in (ÖNORM) EN 13394 or designed according to (ÖNORM) EN 13394. The multi-layer plastic strapping can have a tensile strength of at least 300 N / mm 2 have.

[0059] The first plastic material can, in particular, be formed by a plastic material consisting of 70 wt.% to 98 wt.% thermoplastic, first polymer and 2 wt.% to 30 wt.% of one or more further components. Regardless of the amount of the further component(s) of the first plastic material, this / these further component(s) can be formed, for example, by fillers, additives, plasticizers, or even by one or more polymer(s) other than the first polymer.

[0060] In this context, the first plastic material can, for example, comprise a proportion of foreign polymer, i.e. a different polymer than the first thermoplastic polymer. For example, a proportion of foreign polymer can be from 2 wt.% to 30 wt.%. The foreign polymer can certainly comprise a layer-forming gas or liquid barrier plastic and / or a copolymer. However, the first plastic material can also comprise a proportion of inorganic fillers, for example a proportion of inorganic fillers of 2 wt.% to 30 wt.%, in particular 5 wt.% to 30 wt.%. The inorganic filler can, for example, be formed by chalk, talc or a mixture thereof. Independently of this or additionally, the first plastic material can comprise solid particles with a particle size of up to 500 pm, in particular 150 pm to 500 pm.The first plastic material may also comprise dyes, such as printing inks, for example, in a proportion of 2% to 30% by weight. Preferably, the first plastic material may be a post-consumer recycled (PCR) plastic material.

[0061] In addition to the exclusively mechanically recycled plastic material, the first plastic material can also contain up to 50 wt.% non-recycled or chemically recycled plastic material. Preferably, the first plastic material can consist of a proportion of 80 wt.% to 100 wt.% exclusively mechanically recycled plastic material and additionally up to 20 wt.% non-recycled or chemically recycled plastic material. Regardless of the origin or processing, the first plastic material, as specified in the claims, consists of 70 wt.% to 100 wt.% of the thermoplastic, first polymer and 0 wt.% to 30 wt.% of the further component or components. The thermoplastic, first polymer can be formed, for example, from polyethylene terephthalate, polypropylene, polyethylene, polyamide, or polystyrene.In particular, the first plastic material may consist entirely of exclusively mechanically recycled plastic material.

[0062] The second plastic material can be formed from a non-recycled or chemically recycled plastic material, or from a high-quality, mechanically recycled plastic material, in particular from a mechanically recycled post-industrial recycled plastic material. The second plastic material also applies that, regardless of the amount of the additional component(s) of the second plastic material, this or these additional components can be formed, for example, by fillers, additives, plasticizers, or by one or more polymers other than the second, semi-crystalline polymer.

[0063] Unlike the first plastic material, the second plastic material may not comprise printing inks, layer-forming gas or liquid barrier plastic, or high-melting or non-melting components such as metals, wood fillers, glass (fibers), or polymers that melt at high temperatures. Furthermore, the second plastic material may comprise a maximum proportion of 10 wt.%, preferably a maximum of 5 wt.%, of inorganic filler, such as chalk or talc, or, for example, dyes for coloring plastic materials, such as masterbatch dyes. The second plastic material may comprise solid particles with a particle size of up to 150 μm.

[0064] An exclusively mechanically recycled plastic material is understood to be a plastic material that has already been used or employed at least once and in which no chemical recycling, in particular no deliberate chemical reaction, was carried out during the recycling process. As is well known, chemical recycling can occur through chain scission or depolymerization of polymers down to monomers and subsequent re-polymerization. In particular, the first plastic material can be post-consumer and / or post-industrial goods or plastic material. A chemically recycled plastic material is accordingly understood to be a plastic material in which such chemical reactions were deliberately induced during the recycling process, in particular depolymerization and subsequent re-polymerization. A non-recycled plastic material is understood to be a freshly polymerized ormanufactured plastic material which has not yet been used, i.e. a new plastic material or new product.

[0065] Preferably, the multi-layer plastic strapping band may consist of 55 wt% to 90 wt% of the first plastic material and 10 wt% to 45 wt% of the second plastic material.

[0066] The thickness of the multilayer plastic strapping band can be from 0.15 mm to 1.8 mm, preferably from 0.2 mm to 1.4 mm. The width of the multilayer plastic strapping band can be from 3 mm to 40 mm, in particular from 4 mm to 36 mm. The surface layer(s) can be surface-treated and can have, for example, an embossing.

[0067] Such a multilayer plastic strapping band with the specified composition can be produced more sustainably and cost-efficiently than before. This is primarily achieved through the use of a large amount of cost-effectively and sustainably produced or supplied, exclusively mechanically recycled plastic material to form the first plastic material. Surprisingly, it has been proven that such plastic strapping bands have sufficiently good properties for use as strapping bands.

[0068] The first plastic material, or base layer, may also contain significant amounts of components that are not thermoplastic polymers. For example, it has been shown that plastic materials with a high filler content of up to 30% by weight, which are therefore not considered materially recyclable, may also be included.

[0069] In principle, the first, thermoplastic polymer and the second, semi-crystalline, thermoplastic polymer can each be formed from any polymer. However, in this context, it is preferably provided that the first plastic material and the second plastic material are formed from similar plastic materials.

[0070] Similar plastic materials are understood to mean plastic materials that comprise the same type of thermoplastic polymer. Thus, in this embodiment, both the first and second plastic materials can comprise thermoplastic polymers, for example, a polyolefin, a polyester, or a polyamide as the first and second polymers, respectively. Plastic strapping bands constructed in this way exhibit improved adhesion between the base layer and surface layers.

[0071] In particular, an embodiment of the plastic strapping band may be advantageous in which the first plastic material and the second plastic material are formed by plastic materials in which a chemical molecular formula of the thermoplastic, first polymer corresponds to a chemical molecular formula of the semi-crystalline, thermoplastic, second polymer.

[0072] This design of the multi-layer plastic strapping band allows the adhesion of the surface layers and the base layer to be further improved.

[0073] In particular, in the plastic strapping band, it can be provided that the first plastic material and the second plastic material are formed by plastic materials in which both the thermoplastic, first polymer and the semi-crystalline, thermoplastic, second polymer are formed by polypropylene.

[0074] Plastic materials based on polypropylene have proven particularly suitable for the formation of multi-layer plastic strapping.

[0075] In the multi-layer plastic strapping band, it can also be provided that the first plastic material is formed by a plastic material with a content of 2 wt.% to 30 wt.% of filler(s).

[0076] This can, in particular, reduce the manufacturing costs of the multi-layer plastic strapping, since a plastic material with a high filler content is generally cheaper to produce. Furthermore, the plastic strapping can be provided with the first plastic material being a plastic material with a content of 2% to 30% by weight of coloring filler(s).

[0077] Such fillers can be present in the first plastic material as particularly cost-effective materials. Nevertheless, the multilayer plastic strapping band can be printed on at least one of the surface layers, since a surface layer can act as a cover layer for a connected base strand layer, thus easily concealing coloring of the base layer.

[0078] For a better understanding of the invention, it is explained in more detail using the following figures.

[0079] They show in a highly simplified, schematic representation:

[0080] Fig. 1 shows an embodiment of process steps melting plastic materials, combining plastic melts and forming a multi-layer film strand, in side view;

[0081] Fig. 2 shows an embodiment of a method step for cutting a multi-layer film strand, in side view and in plan view from above;

[0082] Fig. 3 shows an embodiment of a method step for stretching multi-layer tape strands in a side view and in a plan view from above;

[0083] Fig. 4 shows an embodiment of further process steps after the stretching of multi-layer tape strands, in side view;

[0084] Fig. 5 shows an embodiment of a multi-layer plastic strapping band, in sectional view.

[0085] By way of introduction, it should be noted that in the variously described embodiments, identical parts are provided with identical reference symbols or component designations. The disclosures contained throughout the description can be applied analogously to identical parts with identical reference symbols or component designations. Furthermore, the positional information chosen in the description, such as top, bottom, side, etc., refers to the directly described and illustrated figure, and these positional information must be applied analogously to the new position in the event of a change in position.

[0086] The present process for the production of multi-layer plastic strapping can be used in particular for the production of strapping as specified in (ÖNORM) EN 13394. The process can therefore be used for the production of multi-layer plastic strapping with a tensile strength of at least 300 N / mm 2be provided.

[0087] The method initially comprises providing plastic materials. A first plastic material 1 is provided, which first plastic material 1 consists of 70 wt.% to 100 wt.% thermoplastic first polymer and 0 wt.% to 30 wt.% of one or more further components. Specifically, the first plastic material 1 can consist of 70 wt.% to 98 wt.% thermoplastic first polymer and 2 wt.% to 30 wt.% of one or more further components. Regardless of the amount of the further component or components of the first plastic material 1, the latter can be formed, for example, by fillers, additives, plasticizers, or by one or more other polymers than the first polymer.

[0088] For example, the first plastic material 1 can be a plastic material with a proportion of foreign polymer, i.e. a different polymer than the first thermoplastic polymer. For example, the proportion of foreign polymer can be from 2 wt.% to 30 wt.%. The foreign polymer can certainly comprise a layer-forming gas or liquid barrier plastic and / or a copolymer. However, the first plastic material 1 can also be a plastic material with a proportion of inorganic fillers, for example with a proportion of inorganic fillers of 2 wt.% to 30 wt.%, in particular 5 wt.% to 30 wt.%. The inorganic filler can be formed, for example, from chalk, talc or a mixture thereof.Independently of this or additionally, a plastic material can be provided as the first plastic material 1 which comprises solid particles with a particle size of up to 500 pm, in particular 150 pm to 500 pm. Accordingly, the first plastic material 1 can be filtered or have been filtered by means of a filter device with a mesh size of 500 pm during melting, or during a melting process preceding the present method. A plastic material comprising dyes, such as printing inks, can also be provided as the first plastic material 1, for example with a proportion of 2 wt.% to 30 wt.% of dyes, in particular printing inks. Preferably, a post-consumer recycling (PCR) plastic material can be provided as the first plastic material 1. A plastic material can also be provided which, during melting orProcessing temperature during the melting of the first plastic material includes non-melting components.

[0089] As shown schematically in Fig. 1, the at least one first plastic material 1 is melted in a subsequent process step by means of an extrusion device 2 to form a first plastic melt 3.

[0090] As shown in the exemplary embodiment shown in Fig. 1, a second plastic material 4 is also provided. This second plastic material 4 consists of 90 wt.% to 100 wt.% of a semi-crystalline, thermoplastic, second polymer and 0 wt.% to 10 wt.% of one or more further components. Regardless of the amount of the further component(s) of the second plastic material 4, the latter can be formed, for example, by fillers, additives, plasticizers, or by one or more other polymer(s) than the semi-crystalline, second polymer.

[0091] Unlike the first plastic material 1, however, the second plastic material 4 can be a plastic material that does not contain any printing inks, any layer-forming gas or liquid barrier plastic, and also any components that do not melt at a melting or processing temperature during the melting of the second plastic material 4, such as metals, wood fillers, glass (fibers), or polymers that melt at a temperature higher than the melting or processing temperature. Furthermore, the second plastic material 4 can be a plastic material that contains a maximum proportion of 10% by weight, preferably a maximum of 5% by weight, of inorganic filler, such as chalk or talc, or also, for example, dyes for coloring plastic materials, such as master batch dyes.The second plastic material 4 can be a plastic material comprising solid particles with a particle size of up to 150 μm. Accordingly, the second plastic material 4 can be filtered or have been filtered during the melting process, or during a melting process preceding the present method, using a filter device with a mesh size of 150 μm.

[0092] As can be seen from Fig. 1, this second plastic material 4 will also be melted in the subsequent process step by means of a further extrusion device 5 to form a second plastic melt 6.

[0093] The first plastic material 1 is provided with a proportion of 50 wt.% to 100 wt.% of exclusively mechanically recycled plastic material. In addition to the exclusively mechanically recycled plastic material, the first plastic material 1 can also comprise up to 50 wt.% of non-recycled or chemically recycled plastic material. Preferably, the first plastic material 1 can be provided with a proportion of 80 wt.% to 100 wt.% of exclusively mechanically recycled plastic material and additionally up to 20 wt.% of non-recycled or chemically recycled plastic material. The thermoplastic, first polymer can be formed, for example, from polyethylene terephthalate, polypropylene, polyethylene, polyamide, or polystyrene. In particular, a plastic material consisting entirely of exclusively mechanically recycled plastic material can be provided as the first plastic material 1.As the second plastic material 4, a non-recycled or chemically recycled plastic material, or also a high-quality, mechanically recycled plastic material, in particular a mechanically recycled post-industrial-recycling plastic material, can be provided.

[0094] Specifically, the first plastic material 1 may be a plastic material having a melt mass flow rate (MFR) according to ISO 1133 of 2 g / 10 min to 35 g / 10 min, and the second plastic material 4 may be a plastic material having a melt mass flow rate (MFR) according to ISO 1133 that is equal to or greater than the first plastic material.

[0095] Preferably, it can be provided that identical plastic materials are provided as the first plastic material 1 and as the second plastic material 4. Specifically, the first plastic material 1 and the second plastic material 4 can be plastic materials in which a chemical formula of the thermoplastic first polymer corresponds to a chemical formula of the semi-crystalline thermoplastic second polymer. In particular, the first plastic material 1 and the second plastic material 4 can be plastic materials in which both the thermoplastic first polymer and the semi-crystalline thermoplastic second polymer are formed from polypropylene.

[0096] Specifically, the first plastic material 1 can be a plastic material with a filler content of 2 wt.% to 30 wt.%. In particular, the first plastic material 1 can be a plastic material with a color-imparting filler content of 2 wt.% to 30 wt.%.

[0097] Following the melting of the two plastic materials 1, 4 and formation of the corresponding plastic melts 3, 6, these two plastic melts 3, 6 are combined, as illustrated in Fig. 1. This procedure involves combining the second plastic melt 6 with a top side 10 and a bottom side 11 of the first plastic melt 3, so that the second plastic melt 6 completely covers the top side 10 and the bottom side 11 of the first plastic melt 3.

[0098] Combining the first plastic melt 3 and the second plastic melt 6 can generally be carried out using several methods known per se. For example, the two plastic melts 3, 6 can be combined using a so-called coextrusion box 12, also referred to as a feed block, as roughly schematically illustrated in Fig. 1, and after combining, can be dispensed via a film extrusion tool 13 with a slot die. As an alternative to the embodiment outlined in Fig. 1, other known methods for combining the plastic melts 3, 6 are of course also conceivable, such as using a so-called coextrusion tool or multi-layer dies, the use of several extrusion tools, each with a nozzle, and so on.

[0099] As can also be seen from Fig. 1, following the combining of the plastic materials 1, 4 or plastic melts 3, 6, a multi-layer film strand 7 is formed. This is accomplished by feeding the combined plastic melts 3, 6 in a material transport direction 8 to a forming device 9, so that the multi-layer film strand 7 is formed from both plastic materials 1, 4. In this way, as shown in Fig. 1, a multi-layer film strand 7 can be formed with a base strand layer 14 made of the first plastic material 1 and surface strand layers 15 made of the second plastic material 4 connected to a top side 15 and a bottom side 16 of this base strand layer 14. This multi-layer film strand 7 is formed such that it consists of 50 wt.% to 95 wt.% of the first plastic material 1 and 5 wt.% to 50 wt.% of the second plastic material 4.In particular, the multilayer film strand 7 can be formed such that it consists of 55 wt.% to 90 wt.% of the first plastic material 1 and 10 wt.% to 45 wt.% of the second plastic material 4.

[0100] In the embodiment shown in Fig. 1, as shown, a three-layer film strand 7 can be formed with a base strand layer 14 made of the first plastic material 1 and with surface strand layers 17 made of the second plastic material 4 connected to an upper side 15 and lower side 16 of this base strand layer 14.

[0101] As further illustrated in Fig. 1, the shaping of the multi-layer film strand 7 can be carried out by means of the shaping device 9, which comprises rotatably mounted rollers 18, 19, 20, 21. The shaping device 9 can therefore be formed, as is known per se, by a rolling mill, also referred to as a calender or smoothing mill, as is also shown in the exemplary embodiment illustrated in Fig. 1. In this case, a film strand thickness 22 of the multi-layer film strand 7 can be specifically adjusted, for example, as is known per se by passing the first plastic melt 3 and the second plastic melt 6 through a gap 23 between adjacent rollers 19, 20. For this purpose, at least one of the adjacent rollers 19, 20 can be adjustable to change the film strand thickness 22. A thickness of the multi-layer film strand 7 after shaping or the thickness shown in Fig.The film strand thickness 22 illustrated in Figure 1 can be set, for example, to 0.6 mm to 3.8 mm, preferably 0.8 mm to 2.8 mm.

[0102] In addition, the plastic materials 1, 4 are also cooled for the subsequent process steps. The cooling of the multilayer film strand 7 to a desired target temperature for the steps can be carried out exclusively by means of the forming device 9 itself. For this purpose, the first plastic melt 3 and the combined second plastic melt 6 can be cooled, for example, by means of at least one temperature-controlled roller 18, 21 or a roller with a temperature-controlled roller surface of the forming device 9. For example, at least one roller 18, 21 of the forming device can be subjected to a coolant.Additionally and / or alternatively, however, a separate cooling of the plastic melts 3, 6 before forming the multilayer film strand 7 and / or an additional, separate cooling of the film strand 7 after forming the multilayer film strand 7 by means of an additional cooling device, such as a water bath, not shown in Fig. 1, can also take place.

[0103] Furthermore, during the process step of forming the multilayer film strand 7, at least one surface 24 of the multilayer film strand 7 can be structured by means of at least one structured roller surface 25. For example, the at least one surface 24 of the multilayer film strand 7 can be provided with a microstructure, in particular with a microstructure not visible to the naked eye in the sense of a matting. Alternatively, for certain applications, it can also be advantageous if the surfaces 24 of the multilayer film strand 7 are designed to be very smooth, i.e., even smoothed by means of at least one roller surface.

[0104] In the exemplary embodiment of the method outlined in Figs. 1 to 4, it can be provided that, as shown in Fig. 2, the multilayer film strand 7, after its shaping and cooling, is divided into individual, undrawn strip strands 26. In Fig. 2, the same reference numerals as in the preceding Fig. 1 are used for the same parts / elements. To avoid unnecessary repetition, reference is made to the detailed description in the preceding Fig. 1.

[0105] This dividing or cutting of the multilayer film strand 7 can take place in particular before the stretching shown in Fig. 3, so that, as shown here, the multilayer, unstretched strip strands 26 are stretched into multilayer, stretched strip strands 33. As shown in Fig. 2, the multilayer film strand 7 can be divided into multilayer, unstretched strip strands 26 along the material transport direction 8 after shaping and before stretching by means of the dividing devices 29. As an alternative to the embodiment shown in Figures 1 to 4, a process can also be provided in which the shaped and cooled, multilayer film strand 7 is first stretched, and such a stretched film strand is only divided into individual, multilayer, stretched strip strands 33 after stretching.If the multilayer film strand 7 is to be divided before stretching, the multilayer film strand 7 can preferably be cooled to a temperature of 75 °C to 135 °C, in particular 80 °C to 130 °C, for a subsequent process step of dividing.

[0106] If the embodiment shown in the figures is followed, as can be seen from Fig. 2, the multi-layer film strand 7 can be divided or cut along the material transport direction 8 into multi-layer, undrawn strip strands 26 with first strip strand widths 27 and first strip strand thicknesses 28 by means of cutting devices 29. The multi-layer film strand 7 can be divided quite generally and regardless of whether the division takes place before or after the stretching, for example by means of round blades that are designed as knife blades, non-rotatable or rotatable along or against the material transport direction, or by means of cutting devices 29 that are designed as lasers or water jets. The number of cutting devices 29 or strip strands 26 in the embodiment according to Fig. 2 are of course only examples, and the respective number of cutting devices 29 orBand strands 26, 33 can of course be varied. In addition to the cutting devices 29 shown in Fig. 2, if necessary or desired, further cutting or dividing devices can also be provided in the edge regions of the multilayer film strand 7 or the outer multilayer band strands 26, 33 in order to trim the edges of the outer band strands 26, 33 or to make them as flat as possible.

[0107] If cutting is carried out before stretching, the method can further provide for at least some of the cutting devices 29 to be adjusted along a direction 30 running parallel to the strip strand widths 27 for setting the first strip strand widths 27, as is illustrated in Fig. 2 by the corresponding double arrows. With this measure, in particular the first strip strand widths 27 can be varied or adjusted as required or desired. For this purpose, the cutting devices 29 can, for example, be adjustably mounted or held on a holding strip 31 aligned parallel to the direction 30 of the strip widths 27, as shown schematically in Fig. 2. In particular, all existing cutting devices 29 can be adjusted along the direction 30 running parallel to the strip strand widths 27 for setting the first strip strand widths 27.In addition, in connection with the adjustment along the direction 30 of the strip strand widths 27, it can also be provided that at least some of the cutting devices 29 are adjusted away from the multilayer film strand 7 or the undrawn, multilayer strip strands 26.

[0108] In the method, as already mentioned, stretching in the material transport direction 8 of either the multilayer film strand 7 or the multilayer, undrawn strip strands 26 is carried out by means of a stretching device 32. In the exemplary embodiment shown in Fig. 3, following the method step of cutting, stretching in the material transport direction 8 of the multilayer, undrawn strip strands 26 is carried out by means of a stretching device 32 to form multilayer, stretched strip strands 33 with second strip strand widths 34 and second strip strand thicknesses 35. In Fig. 3, the same reference numerals or component designations are used for the same parts as in the preceding Figs. 1 and 2. To avoid unnecessary repetition, reference is made to the detailed description in the preceding Figs. 1 and 2.

[0109] As an alternative to the embodiment illustrated in Fig. 3 in conjunction with Fig. 2, it would of course also be possible to stretch the entire multi-layer film strand instead of the multi-layer, unstretched tape strands 26 as shown in Fig. 3, and only then to divide a correspondingly stretched, multi-layer film strand 7 directly into multi-layer, stretched tape strands 33.

[0110] Irrespective of this, as is known per se, the stretching or drawing device 32 can be formed by a so-called stretching unit, in which the multilayer, undrawn tape strands 26, or the multilayer film strand 7, are elongated or stretched in the transport direction 8 by means of successively faster rotating stretching or drawing devices 36, 37. In the embodiment shown in Fig. 3, the multilayer, undrawn tape strands 26 can be elongated or stretched to form the multilayer, stretched tape strands 33. This achieves the desired preferential orientation of the macromolecule chains of the plastic materials 1, 4. Depending on the plastic material(s) 1, 4 used, the multilayer, undrawn tape strands 26, or optionally the multilayer film strand 7, can be stretched at stretch ratios of 1:4 to 1:20.As is known per se, at least one tempering device can also be arranged upstream of the stretching device 32 or, if appropriate, between the take-off devices 36, 37 of the stretching device 32 or the stretching unit, in order to allow targeted tempering of the plastic material 1 or the plastic materials 1, 4 for the stretching process. Such tempering devices, such as water baths, cooling or heating air, or infrared radiators, are generally known from the prior art and are not shown in detail in Fig. 3.

[0111] When proceeding according to the embodiment shown in Figs. 1 to 4, the stretching or elongation of the undrawn, multi-layered strip strands 26 is naturally accompanied by a deformation, in particular by a reduction in cross-section, so that the second strip strand widths 34 and thicknesses 35 are smaller than the first strip strand widths 27 and thicknesses 28, as can also be seen from Fig. 3. By stretching, the second strip strand thicknesses 35 can be adjusted, for example, to a value of 0.15 mm to 1.8 mm, preferably 0.2 mm to 1.4 mm. In the illustrated embodiment, the second band strand widths 34 can be adjusted to a value of 3 mm to 40 mm, in particular 4 mm to 36 mm, by cutting and subsequent stretching, wherein the second band strand widths 34 can be selected predominantly according to the respective intended use for the plastic strapping bands.If, alternatively, the multilayer film strand 7 is stretched as a whole and only then divided into the multilayer, stretched tape strands 33, the same applies, of course, with regard to the second tape strand widths 34 and second tape strand thicknesses 35.

[0112] If the multilayer film strand 7 is divided before the stretching process step, as is best seen by looking at Fig. 2 and Fig. 3 together, the process can provide for actual values ​​of the second strip strand widths 34 to be recorded by means of at least one sensor device 38 following the stretching, and based on these determined actual values, the cutting devices 29 are adjusted with regard to respective desired target values ​​for the second strip strand widths 34 along the direction 30 running parallel to the strip strand widths 34 in order to set the first strip strand widths 27. The sensor device 38 can be formed by an optical sensor device, in particular by a camera.

[0113] As can also best be seen by looking at Fig. 2 and Fig. 3 together, in the exemplary embodiment it can further be provided that the detected actual values ​​of the second strip strand widths 34 are transmitted from the sensor device 38 to a control device 39 and the cutting devices 29 are adjusted in an automated manner along the direction 30 running parallel to the strip strand widths 27, 34 by the control device 39 to set the first strip strand widths 27. A signaling connection between the sensor device 38, Fig. 3, and the cutting devices 29, Fig. 2, with the control device 39 is indicated in Figs. 2 and 3 by the dashed lines.

[0114] Irrespective of this, in the method, following the stretching of the multi-layer film strand 7 or the multi-layer, undrawn strip strands 26, actual values ​​of the second strip strand thicknesses 35 can be recorded by means of at least one sensor device 40, and by means of the shaping device 9, one or the film strand thickness 22 of the multi-layer film strand 7 can be adjusted with regard to the respective desired target values ​​for the second strip strand thicknesses 35, as is best seen by comparing Fig. 1 with Fig. 3. The at least one sensor device 40 for determining the actual values ​​of the second strip strand thicknesses 35 can in turn be formed by an optical sensor, in particular a camera. In this case, essentially the same sensor device 38 can be used which is also used to determine the second strip strand widths 34, or of course also a separate sensor device 40, as shown in Fig.3 is illustrated.

[0115] Also, in connection with the detection of the actual values ​​of the second strip strand thicknesses 35, it can be provided that these detected actual values ​​of the second strip strand thicknesses 35 are transmitted from the sensor device 40 to a control device 39, and the film strand thickness 22 is adjusted in an automated manner by controlling the shaping device 9 by means of the control device 39. The signal connections required for this purpose between the sensor device 40 and the shaping device 9 and the control device 39 are indicated by dashed lines in Fig. 1 and Fig. 3.

[0116] Fig. 4 illustrates further possible steps of the process following stretching and dividing. In Fig. 4, the same reference numerals or component designations are used for identical parts as in the preceding Figs. 1 to 3. To avoid unnecessary repetition, reference is made to the detailed description in the preceding Figs. 1 to 3.

[0117] For example, it can be provided that the multi-layer, stretched tape strands

[0118] 33, or one or both of their surfaces, are subjected to a surface treatment by means of one or more surface treatment devices 41. Such a surface treatment may, for example, comprise coating the surface(s), such as with a wax or other coating agent. However, a surface treatment may also comprise, for example, irradiation or plasma treatment of the surface(s) of the multilayer, stretched tape strands 33.

[0119] Furthermore, one or both surfaces of the multilayer, stretched ribbon strands 33 can be embossed, for example, by means of an embossing device 42. This may be in addition to the previously mentioned structuring by means of the shaping device 9.

[0120] Finally, the multi-layer, stretched tape strands 33 can be finished, as also illustrated in Fig. 4, for example wound onto the winding device 43 shown in Fig. 4, often also referred to as a spooler, and thus prepared for transport.

[0121] Finally, Fig. 5 shows a roughly schematic sectional view of an embodiment of a multi-layer plastic strapping band 44. The plastic strapping band 44 shown in Fig. 5 can be manufactured in particular according to or with the method already described. The multi-layer plastic strapping band 44 can be a strapping band as specified in (ÖNORM) EN 13394 or can be designed according to (ÖNORM) EN 13394. The multi-layer plastic strapping band 44 can have a tensile strength of at least 300 N / mm 2 have.

[0122] As can be seen from Fig. 5, the plastic strapping band 44 consists of a base layer 45 made of one or the first plastic material 1 as well as a surface layer 48 made of one or the second plastic material 4, each connected to a top side 46 and a bottom side 47 of this base layer 45. In the illustrated embodiment, it can therefore be provided that the multi-layer plastic strapping band 44 is formed in three layers

[0123] The first plastic material 1, from which the base layer 45 consists, is formed by 70 wt.% to 100 wt.% thermoplastic, first polymer and 0 wt.% to 30 wt.% of a further component or several further components. The second plastic material 4, from which the surface layers consist, is formed by 90 wt.% to 100 wt.% semi-crystalline, thermoplastic second polymer and 0 wt.% to 10 wt.% of a further component or several further components.

[0124] The first plastic material 1 has a proportion of 50 wt.% to 100 wt.% of exclusively mechanically recycled plastic material. The multilayer plastic strapping band 44 consists of 50 wt.% to 95 wt.% of the first plastic material 1 and 5 wt.% to 50 wt.% of the second plastic material 4.

[0125] The first plastic material 1 can, in particular, be formed by a plastic material consisting of 70 wt.% to 98 wt.% thermoplastic, first polymer and 2 wt.% to 30 wt.% of one or more further components. Regardless of the amount of the further component or components of the first plastic material 1, this or these further components can be formed, for example, by fillers, additives, plasticizers, or even by one or more polymers other than the first polymer.

[0126] The first plastic material 1 can, for example, comprise a proportion of foreign polymer, i.e. a different polymer than the first thermoplastic polymer. For example, a proportion of foreign polymer can be from 2 wt.% to 30 wt.%. The foreign polymer can certainly comprise a layer-forming gas or liquid barrier plastic and / or a copolymer. However, the first plastic material 1 can also comprise a proportion of inorganic fillers, for example a proportion of inorganic fillers of 2 wt.% to 30 wt.%, in particular 5 wt.% to 30 wt.%. The inorganic filler can, for example, be formed by chalk, talc or a mixture thereof. Independently of this or additionally, the first plastic material 1 can comprise solid particles with a particle size of up to 500 μm, in particular 150 μm to 500 μm. The first plastic material 1 can also contain dyes, such as printing inks, for example in a proportion of 2 wt.% to 30 wt.% to 30 wt.%. Preferably, the first plastic material 1 can be a post-consumer recycling (PCR) plastic material.

[0127] In addition to the exclusively mechanically recycled plastic material, the first plastic material 1 can also contain up to 50 wt.% non-recycled or chemically recycled plastic material. Preferably, the first plastic material 1 can consist of a proportion of 80 wt.% to 100 wt.% of exclusively mechanically recycled plastic material and additionally up to 20 wt.% non-recycled or chemically recycled plastic material. Regardless of the origin or processing, the first plastic material 1, as specified in the claims, consists of 70 wt.% to 100 wt.% of the thermoplastic, first polymer and 0 wt.% to 30 wt.% of the further component or components. The thermoplastic, first polymer can be formed, for example, from polyethylene terephthalate, polypropylene, polyethylene, polyamide, or polystyrene.In particular, the first plastic material may consist entirely of exclusively mechanically recycled plastic material.

[0128] The second plastic material 4 can be formed from a non-recycled or chemically recycled plastic material, or else from a high-quality, mechanically recycled plastic material, in particular from a mechanically recycled post-industrial recycled plastic material. The second plastic material 4 can also be formed, for example, by fillers, additives, plasticizers, or by one or more polymers other than the second, semi-crystalline polymer, regardless of the amount of the additional component(s) of the second plastic material.

[0129] Unlike the first plastic material 1, the second plastic material 4 may not comprise printing inks, layer-forming gas or liquid barrier plastic, or high-melting or non-melting components such as metals, wood fillers, glass (fibers), or polymers that melt at high temperatures. Furthermore, the second plastic material 4 may comprise a maximum proportion of 10 wt.%, preferably a maximum of 5 wt.%, of inorganic filler, such as chalk or talc, or, for example, dyes for coloring plastic materials, such as masterbatch dyes. The second plastic material 4 may comprise solid particles with a particle size of up to 150 μm.

[0130] Preferably, the multi-layer plastic strapping band 44 may consist of 55 wt.% to 90 wt.% of the first plastic material 1 and 10 wt.% to 45 wt.% of the second plastic material 4.

[0131] The thickness of the multilayer plastic strapping band 44, shown purely by way of example and roughly schematically in Fig. 5, can be, for example, 0.15 mm to 1.8 mm, preferably 0.2 mm to 1.4 mm. The width of the multilayer plastic strapping band 44 can be 3 mm to 40 mm, in particular 4 mm to 36 mm. The surface layer(s) 48 can be surface-treated and can, for example, have an embossing 49, as can also be seen from the exemplary embodiment shown in Fig. 5.

[0132] In principle, the first, thermoplastic polymer and the second, semi-crystalline, thermoplastic polymer can each be formed by any polymers.

[0133] In this context, however, it can preferably be provided that the first plastic material 1 and the second plastic material 4 are formed from similar plastic materials. In particular, the first plastic material 1 and the second plastic material 2 can be formed from plastic materials in which a chemical formula of the thermoplastic, first polymer corresponds to a chemical formula of the semi-crystalline, thermoplastic, second polymer. In particular, the first plastic material 1 and the second plastic material 4 can be formed from plastic materials in which both the thermoplastic, first polymer and the semi-crystalline, thermoplastic, second polymer are formed from polypropylene. The first plastic material 1 can be formed from a plastic material with a filler content of 2 wt.% to 30 wt.%.In particular, the first plastic material 1 can be formed by a plastic material with a content of 2 wt.% to 30 wt.% of coloring filler(s).

[0134] The embodiments show possible embodiments, whereby it should be noted at this point that the invention is not limited to the specifically illustrated embodiments thereof, but rather various combinations of the individual embodiments with each other are also possible and this possibility of variation lies within the skill of the person skilled in the art in this technical field due to the teaching of technical action by means of the objective invention.

[0135] The scope of protection is determined by the claims. However, the description and the drawings must be used to interpret the claims. Individual features or combinations of features from the various embodiments shown and described can represent independent inventive solutions in themselves. The problem underlying the independent inventive solutions can be derived from the description. All information on value ranges in this description is to be understood as including any and all sub-ranges thereof. For example, the reference 1 to 10 is to be understood as including all sub-ranges starting from the lower limit of 1 and the upper limit of 10. This means that all sub-ranges begin with a lower limit of 1 or greater and end with an upper limit of 10 or less, for example 1 to 1.7, or 3.2 to 8.1, or 5.5 to 10.

[0136] For the sake of clarity, it should finally be pointed out that, in order to better understand the structure, some elements have been shown out of scale and / or enlarged and / or reduced in size.

[0137] Reference symbol list

[0138] Plastic material 32 stretching device

[0139] Extrusion device 33 Strip plastic melt 34 Strip width

[0140] Plastic material 35 strand thickness

[0141] Extrusion device 36 Pulling device plastic melt 37 Pulling device

[0142] Film strand 38 sensor device

[0143] Material transport direction 39 control device

[0144] Shaping device 40 Sensor device top 41 Surface treatment device

[0145] Bottom tung

[0146] Coextrusion box 42 embossing device

[0147] Film extrusion tool 43 winding device

[0148] Base strand layer 44 plastic strapping

[0149] Top 45 Base layer

[0150] Bottom 46 Top

[0151] Surface strand layer 47 Bottom

[0152] Roller 48 surface layer

[0153] Roller 49 embossing

[0154] roller

[0155] roller

[0156] Film strand thickness

[0157] gap

[0158] surface

[0159] Roller surface

[0160] Band strand

[0161] Band width

[0162] Strip thickness

[0163] Cutting device

[0164] Direction

[0165] retaining strips

Claims

Patent claims 1. Process for the production of multi-layer plastic strapping (44), comprehensive, - Providing a first plastic material (1) consisting of 70 wt.% to 100 wt.% of a thermoplastic, first polymer and 0 wt.% to 30 wt.% of a further component or several further components, and providing a second plastic material (4) consisting of 90 wt.% to 100 wt.% of a semi-crystalline thermoplastic, second polymer and 0 wt.% to 10 wt.% of a further component or several further components, - melting the first plastic material (1) by means of an extrusion device (2) to form a first plastic melt (3) and melting the second plastic material (4) by means of a further extrusion device (5) to form a second plastic melt (6), - combining the first plastic melt (3) and the second plastic melt (6) such that the second plastic melt (6) completely covers an upper side (10) and a lower side (11) of the first plastic melt (3), - forming a multi-layer film strand (7) by feeding the first plastic melt (3) and the second plastic melt (6) in a material transport direction (8) to a forming device (9), and cooling the first plastic material (1) and the second plastic material (4) so ​​that a base strand layer (14) and surface strand layers (17) connected to an upper side (15) and a lower side (16) of this base strand layer (14) are formed, - cutting the multi-layer film strand (7) along the material transport direction (8) into multi-layer band strands (26, 33) by means of cutting devices (29), - stretching in the material transport direction (8) of the multi-layer film strand (7) or the multi-layer band strands (26) by means of a stretching device (32), characterized in that the first plastic material (1) is provided with a proportion of 50 wt.% to 100 wt.% of exclusively mechanically recycled plastic material, and in that the multi-layer film strand (7) is shaped in such a way that it consists of 50 wt.% to 95 wt.% of the first plastic material (1) and 5 wt.% to 50 wt.% of the second plastic material (4).

2. Method according to claim 1, characterized in that a plastic material with a melt mass flow rate (MFR) according to ISO 1133 of 2 g / 10 min to 35 g / 10 min is provided as the first plastic material (1), and in that a plastic material with a melt mass flow rate (MFR) according to ISO 1133 that is the same or greater than the first plastic material (4) is provided as the second plastic material (4).

3. Method according to claim 1 or 2, characterized in that plastic materials of the same type are provided as the first plastic material (1) and as the second plastic material (4).

4. The method according to claim 3, characterized in that as the first plastic material (1) and as the second plastic material (4) plastic materials are provided in which a chemical formula of the thermoplastic first polymer corresponds to a chemical formula of the semi-crystalline thermoplastic second polymer.

5. The method according to claim 4, characterized in that as the first plastic material (1) and as the second plastic material (4) plastic materials are provided in which both the thermoplastic, first polymer and the semi-crystalline, thermoplastic, second polymer are formed by polypropylene.

6. Method according to one of the preceding claims, characterized in that a plastic material with a content of 2 wt.% to 30 wt.% of filler(s) is provided as the first plastic material (1).

7. The method according to claim 6, characterized in that the first plastic material (1) is a plastic material having a content of 2 wt.% to 30 wt.% of coloring filler(s).

8. Method according to one of the preceding claims, characterized in that the multi-layer film strand (7) is divided into multi-layer tape strands (26) after shaping and before stretching by means of the dividing devices (29).

9. The method according to claim 8, characterized in that the multilayer film strand (7) is cooled to a temperature of 75 °C to 135 °C for the cutting step.

10. Multi-layer plastic strapping band (44), consisting of a base layer (45) made of a first plastic material (1) and surface layers (48) made of a second plastic material (4) connected to a top side (46) and a bottom side (47) of this base layer (45), wherein the first plastic material (1) is formed by 70 wt.% to 100 wt.% thermoplastic, first polymer and 0 wt.% to 30 wt.% of a further component or several further components, and wherein the second plastic material (4) is formed by 90 wt.% to 100 wt.% semi-crystalline, thermoplastic second polymer and 0 wt.% to 10 wt.% of a further component or several further components, characterized in that the first plastic material (1) has a proportion of 50 wt.% to 100 wt.% of exclusively mechanically recycled plastic material, wherein the multi-layer plastic strapping band consists of 50 wt.% to 100 wt.%% to 95 wt.% of the first plastic material (1) and 5 wt.% to 50 wt.% of the second plastic material (4).

11. Multi-layer plastic strapping band (44) according to claim 10, characterized in that the first plastic material (1) and the second plastic material (4) are formed by plastic materials of the same type.

12. Multi-layer plastic strapping band (44) according to claim 11, characterized in that the first plastic material (1) and the second plastic material (4) are formed by plastic materials in which a chemical formula of the thermoplastic first polymer corresponds to a chemical formula of the semi-crystalline thermoplastic second polymer.

13. Multi-layer plastic strapping band (44) according to claim 12, characterized in that the first plastic material (1) and the second plastic material (4) are formed by plastic materials in which both the thermoplastic, first polymer and the semi-crystalline, thermoplastic, second polymer are formed by polypropylene.

14. Multi-layer plastic strapping band (44) according to one of claims 10 to 13, characterized in that the first plastic material (1) is formed by a plastic material with a content of 2 wt.% to 30 wt.% of filler(s).

15. Multi-layer plastic strapping band (44) according to one of claims 10 to 14, characterized in that the first plastic material (1) is formed by a plastic material with a content of 2 wt.% to 30 wt.% of coloring filler(s).

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