Patent Application
20240093427
The invention relates to a textile fabric with a surface coating.
Coated textiles are generally well known. Polyvinyl chloride (PVC) is often used as coating material. In the document DE 19926732, for example, a knitted fabric made from polyester fibres is coated with PVC in a reverse method. Furthermore, it is known from the document WO 2012/022626 to coat a support material with a coating material made from a polyolefin-homopolymer or a polyolefin-copolymer. In document CN 110725135, a textile fabric is disclosed, where a coating made from a combination of polyethylene and ethylene-vinyl acetate copolymer is used. In the examples of this document, the content of ethylene-vinyl acetate copolymer is in the range of at most 25 wt. % and the use of the textile fabric is considered to be primarily in the field of household goods. The document U.S. Pat. No. 3,660,150 also describes a textile fabric with a surface coating. The surface coating can also consist of a mixture of polyethylene and ethylene-vinyl acetate copolymer.
WO 2018/104101 also discloses a textile fabric with a support layer made from polyethylene, for example, wherein the textile fabric has a coating made from a mixture of polyethylene and polyethylene-vinyl acetate on at least one surface.
The textile fabric of WO 2018/104101 is a fleece that is coated by means of spray impregnation and is used in wheel housings of automobiles for noise suppression, but at the same time shows good dirt and ice resistance.
A disadvantage of the known coated textiles is that toxic decomposition products are often produced when the textiles are incinerated or disposed of as waste if, for example, polyvinyl chloride (PVC) is used as coating material. The disadvantage of using polyolefins as a coating material is that the methods for further processing of such coated textiles (for example the lacquering or the provision of finished products) are often very complex.
It was therefore the object of the present invention to provide a coated textile fabric that has at least better environmental compatibility of the coating and that is nevertheless easy processable and well adaptable to different uses.
The object is achieved by a textile fabric with a woven support layer, wherein the support layer consists of at least polyethylene and/or polyester fibres, A surface coating is applied onto at least one of the surfaces of the support layer, wherein the surface coating consists of at least one polymer blend, wherein the polymer blend has at least one mixture of polyethylene (PE) and polyethylene-vinyl acetate (PEVA). The content of polyethylene-vinyl acetate in the polymer blend is at least 40 wt. %, based on the total weight of the polymer blend. By using a polyethylene-vinyl acetate with the indicated content by weight in the coating material, the coating material has surprising new properties which a pure PE coating material or a polymer blend with less polyethylene-vinyl acetate in the polymer blend does not have. For example, the textile fabric of the present invention can be further processed with lacquers that would not or only poorly adhere to a pure PE coating. Moreover, the textile fabric according to the invention has a surface coating that is more weather-resistant than PVC coatings and also emits fewer pollutants. Furthermore, particularly advantageously, a textile fabric with the described content of polyethylene-vinyl acetate can be further processed by means of high-frequency welding, as a result of which the textile fabric can be further processed more easily and new uses for the textile fabric are also possible.
Moreover, the surface of the woven support layer coated in this way has a very smooth surface, so that it is printable in a simple and diverse manner. Therefore, the textile fabric according to the invention is particularly suitable for use, for example, as a tarpaulin or cover for trucks or as woven fabrics of any kind.
A surface coating consisting of at least one polymer blend should be understood to mean that the surface coating consists entirely of the polymer blend or consists predominantly of the polymer blend.
In one embodiment, the surface coating consists of more than 70 wt. %, more than 80 wt %, more than 90 wt % or 100 wt. % of the polymer blend, based on the total weight of the surface coating.
In the present invention, polyethylene-vinyl acetate is abbreviated as PEVA, polyethylene as PE, and vinyl acetate as VA, The abbreviation PVC is used for polyvinyl chloride.
In one embodiment, the polymer blend has a content of PEVA in the polymer blend of 45 wt. %, preferably 49 wt %, more preferably 50 wt % and further preferably 55 wt % and even further preferably 60 wt. %, based on the total weight of the polymer blend.
In one embodiment of the textile fabric, the polyethylene-vinyl acetate in the polymer blend has a vinyl acetate (VA) content of 5-50 wt. %, preferably 10-40 wt. %, more preferably 15 to 30 wt. %, even more preferably 20 to 25 wt. %, based on the weight in the polymer blend. Advantageously, the textile fabric can be processed by means of high-frequency welding from a content of vinyl acetate of about 10 wt,% (based on the total weight of the polymer blend), which is also not possible with a pure PE coating. As a result, several options are available for the further processing of the textile fabric, which then ultimately also expand the field of use of the textile fabric. Moreover, the content of about 10 wt % of vinyl acetate in the polymer blend gives the surface coating or the textile fabric a flexibility and softness such as can be found, for example, in soft polyvinyl chloride. In one embodiment, the polyethylene-vinyl acetate in the polymer blend has a vinyl acetate content of 15 wt. % to more than 40 wt. %, based on the total weight of the polyethylene-vinyl acetate. In one embodiment with more than 40 wt. % of vinyl acetate, the PEVA material in the polymer blend becomes rubbery, as a result of which a use in the field of bags, foils or shoe manufacture (in particular soles), for example, is made possible.
In one embodiment, the polymer blend also has polypropylene in addition to the PEVA and the PE.
The polymer blend has a mixture of polyethylene and polyethylene-vinyl acetate, wherein the mixture makes it possible to achieve certain properties in terms of the processability of the coating. The polyethylene has a melting point of 135-145° C., which means that it can be easily processed on melt calender systems. Polyethylene-vinyl acetate has a variable melting point that depends on the vinyl acetate content. A content of about 7 wt. % of vinyl acetate in the polyethylene-vinyl acetate, for example, results in a melting point of about 104° C. and a content of 28 wt % of vinyl acetate results in a melting point of about 70° C. By using a mixture of PE and PEVA in the above-mentioned ranges a processing on common calender systems and a prior extrusion step can be realized. It would probably be difficult to process pure PEVA on conventional calender systems.
By adding PEVA to PE, mixing properties of both polymers can be obtained, such as high-frequency weldability or improved weathering stability and a lower tendency for forming stress cracks by the PEVA. PE itself has good chemical resistance.
As described, the textile fabric and the surface coating of the textile fabric, respectively, can advantageously be heated by means of high-frequency energy in the form of an electromagnetic field (high-frequency welding). Under the heat and pressure, the surface coating of the textile fabric begins to melt and can thus be joined together with other parts of the textile fabric, with other textile fabrics of the same or different type (fusible) or with completely different materials (such as a coating of PE Material). In this process, no heat is supplied from the outside, which means that fewer protective measures for occupational safety are required. The heat is generated in the textile fabric and in the surface coating of the textile fabric, respectively, and is therefore particularly effective. During the cooling process (for example, under constant pressure), a fusing of the different materials with one another occurs and a weld seam is formed. A very strong connection can be brought about in this way, which also does not impair the weather resistance, for example, the water impermeability, of the textile fabric. Another advantage of this type of connection of the textile fabric is that the process described does not produce a large amount of harmful vapours or combustion residues over a large area. Depending on the fibres used in the support layer, the high-frequency welding can also cause the fibres of the support layer to melt completely or at least partially. Partially melted or completely melted fibres within the seam can give the seam a certain stability which, for example, facilitates the shaping of the textile fabric.
The textile fabric can also advantageously be connected to other materials by means of other (conventional) welding processes. For example, the textile fabric can be connected to other textile fabrics with a coating of polyethylene and/or polypropylene by means of hot-air welding. When the textile fabric was hot-air welded to another textile fabric with a polyethylene coating, an adhesion value of more than about 50 N/cm could be measured without edge waviness. When the textile fabric was hot-air welded to another textile fabric with a polypropylene coating, an adhesion value of more than about 50 N/cm could also be measured without edge waviness. In all cases, the adhesion value is determined using the standard ISO 2411:2017 (EN ISO 2411:2017), wherein the second method of sample preparation of the standard is to be used and the values that are measured in the machine direction (i.e., in warp direction) are to be applied to the measurement of test specimens.
In one embodiment of the invention, the support layer is constructed entirely from fibres made from polyethylene and/or polyester. In a preferred embodiment, the support layer is constructed entirely from polyester fibres. Entirely constructed means that the support layer is constructed from more than 80%, preferably more than 90% and most preferably 100% of the fibres mentioned. In the case of a combination of polyethylene and polyester, the support layer is preferably constructed from a yarn mixture of fibres made from polyethylene and polyester. For example, high-strength polyethylene fibres such as those available under the trade names Dyneema (Fa. DSM B.V.) or Spectra (Fa, Honeywell International) can be used as polyethylene fibres. Diolen®, Fa. Polyester High Performance Fibres, for example, can be used as polyester fibres. A support layer constructed from the fibres mentioned or a mixture of the fibres mentioned has the advantage that the support layer is easy to manufacture and becomes adaptable to various technical requirements, such as strength of the support layer, due to the wide selection of possible fibre types.
The term fibre should be understood to mean both endless fibres and staple fibres or short fibres. The fibres can belong both to a multifilament yarn and to a monofilament yarn.
In one embodiment, the polymer blend of the surface coating has less than 51 wt. % polyethylene, based on the total weight of the polymer blend. In one embodiment, the polymer blend consists of at least 95 wt. % of a combination of polyethylene and polyethylene-vinyl acetate, based on the total weight of the polymer blend. The surface coating preferably has less than 20 wt. %, more preferably less than 15 wt. %, even more preferably less than 10 wt. % and most preferably less than 5 wt. % of other components—such as additives—in addition to the polymer blend, Such a surface coating has the advantage that the mentioned mixture of PE and PEVA combines both advantages of the mentioned substances without the disadvantages of the respective substances adversely affecting the surface coating. For example, the surface coating has good long-term stability due to the PE contained therein. PEVA is particularly robust and thus increases the longevity of a surface coating, especially with regard to mechanical effects on the surface coating. Furthermore, the PEVA forms the basis for the textile fabric becoming processable by means of high-frequency welding and improves the ability of the surface coating to be lacquered. Moreover, plasticizers or substances containing halogens can be dispensed with in such a surface coating made from the mentioned combination of PE and PEVA, which prevents the risk that chemicals containing halogens or plasticizer components can diffuse to the surface of the surface coating and there engage in undesirable interactions with, for example, a lacquering. This makes the textile fabric more environmentally friendly and its chemical properties remain constantly stable even over a longer life cycle of the textile fabric. A further advantage of choosing the polymer blend for the surface coating is that the textile fabric is due to the omission of the plasticizer more skin-friendly than, for example, textile fabrics with PVC coatings with plasticizer. In particular, this simplifies the processing of such skin-friendly textile fabrics for manufacturers, for example, and the textile fabric can also be provided for new uses in which, for example, regular skin contact with the textile fabric can occur.
In embodiments of the textile fabric, the support layer is a woven fabric or a twisted woven fabric (Gedrebe). The support layer is most preferably a woven fabric which has a twill, plain, panama or satin weave. The support material can be single-layered or multi-layered, wherein the support layer is able to have the aforementioned bonds single-layered or multi-layered. For example, the support layer can be constructed multi-layered and consist of at least two woven fabric layers or of one woven fabric layer and one twisted woven fabric layer.
In one embodiment, the surface coating on the at least one surface of the support layer is applied over the entire surface. Over the entire surface means here that there are essentially no longer any areas of the support layer surface without coating material after the coating of this surface. When using, for example, a very open grid as the support layer, a coating applied over the entire surface can also mean that although the grid does not have any areas without coating on the surface to be coated, gaps between the grids remain free. Neither material of the support layer nor material of the coating is present within the gaps. The textile fabric is preferably coated on both surface sides of the support layer over the entire surface. Particularly preferred, the coating of the two surface sides of the support layer is done with the same surface coating. However, a coating with different surface coating materials for various surface sides is also conceivable. In one embodiment, bars made from coating material are formed within the support layer by coating both surfaces, wherein the bars connect the two surface coatings to one another. In another embodiment of the textile fabric, no or only a small number of bars made from coating material form within the support layer, wherein the bars result in no or only a small number of connections between the two surface coatings of the support layer.
In one embodiment, the coating of the support layer with the polymer blend is done integrally. Here, integrally means that the coating material (polymer blend) is applied onto the support material essentially as a coherent coating mass, for example, as a melt or foil, and not, for example, as spray particles, which then form a coating of the entire surface, for example. The advantage of an integral coating is that the surface of the coating is particularly flat and, as a result, the surface quality is high, for example. Thus, later printability with better quality is then also possible, for example.
In a further preferred embodiment, the polymer blend of the surface coating is polyvinyl chloride-free. In this context, polyvinyl chloride-free means that the polymer blend has less than 1 wt. %, most preferably 0 wt. % polyvinyl chloride, based on the total weight of the polymer blend. In a further preferred embodiment, the surface coating is polyvinyl chloride-free, which is also intended to mean here that the surface coating contains less than 1 wt. %, most preferably 0 wt % polyvinyl chloride, based on the total weight of the surface coating. In this case, neither the polymer blend nor the surface coating has polyvinyl chloride—as a further component in addition to the polymer blend. Without the use of polyvinyl chloride, both the manufacture and the recycling of the textile fabric are significantly more environmentally friendly and the skin-friendliness of the textile fabric is also increased. For example, the highly toxic gas vinyl chloride is not used in the production of PE and PEVA.
In one exemplary embodiment, the adhesion value for the welding of at least two textile fabrics (according to claim 1) to one another by means of high-frequency welding is at least 8 N/cm. Preferably, the adhesion value for the welding of at least two textile fabrics to one another by means of high-frequency welding is about 12 N/cm, preferably about 15 N/cm, preferably about 20 N/cm, more preferably about 25 N/cm, even more preferably about 30 N/cm, most preferably about 60 N/cm and most preferably about 70 N/cm. The adhesion value is determined using the standard ISO 2411:2017 (EN ISO 2411:2017), wherein the second method of sample preparation of the standard is to be used and the values that are measured in the machine direction (i.e., in warp direction) are to be applied to the measurement of test specimens.
A further object of the invention relates to a method for manufacturing the textile fabric, wherein the textile fabric has the features as described above. In the method, a support layer, which has at least polyethylene and/or polyester fibres, is coated with a surface coating by means of a melt calender on at least one surface of the support layer. For coating the surface, a surface coating is selected that consists of at least one polymer blend, wherein the polymer blend has at least one mixture of polyethylene and polyethylene-vinyl acetate. The polymer blend has more than 40 wt. % polyethylene-vinyl acetate, based on the total weight of the polymer blend. It goes without saying that the surface coating is present as a melt during manufacture and is processed as a homogeneous layer in a correspondingly flowable manner (there is therefore no foil of surface coating material that is laminated on by means of a roller and no spray coating by means of matrix droplets or powders). Preferably, one surface of the support layer but most preferably both surfaces of the support layer are coated with the surface coating as described above.
During the manufacture of the textile fabric, the support layer is preferably coated over a width of more than three meters on the upper side of the support layer by means of the melt calender in a single process step. As a result, a coating web of surface coating, which has a width of at least three meters, is formed on the support layer in a single coating operation. In this way, larger textile fabrics, which have a continuous web of coating material, can also be manufactured in an advantageous manner. Advantageously, overlapping areas of coating material do not form in this case, or less frequently in the case of a width of more than three meters. In an advantageous manner, the printability of the textile fabric is thus again improved, since not only does the woven support layer enable an even coating, but the coating itself also enables a special surface quality.
A further object of the present invention relates to the use of the textile fabric, manufactured as described above and having the features as described above. The textile fabric can be further processed for shaping and fixing by means of high-frequency welding. For example, a truck tarpaulin, a bag, a container or the like can be manufactured from the textile fabric, which is preferably present as web material, by means of high-frequency welding. The textile fabric is preferably formed and/or fixed exclusively by means of high-frequency welding. Of course, the textile fabric can also be processed using alternative welding methods, such as by means of hot air. Advantageously, when using alternative welding methods (unlike during the processing of textiles with PVC in the coating), no toxic fumes are produced during welding, so that less strict occupational safety measures have to be taken into account during processing.
The surface coating of the textile fabric, with the features as described above, can be lacquered, for example, in which case a polyvinyl chloride-free lacquer or a polyvinyl chloride-containing lacquer can preferably be used. Although the surface coating of the textile fabric contains a not inconsiderable content of PE, it is surprisingly possible to coat or paint the surface coating (and thus the textile fabric) with a PVC-free lacquer or with a polyvinyl chloride-containing lacquer. In the case of surface coatings without an EVA content, this is not possible or only possible with difficulties, or is only possible by using a larger quantity of additional adhesion promoters or, for example, only after pre-treatments (e.g., corona treatments) of the surface before coating. For special lacquers, however, the use of adhesion promoters is still possible and a corona treatment can also be performed if this is desired. Furthermore, the preparation of the textile fabric before lacquering appears to be shortened or simplified. The use of a smaller amount of adhesion promoter can also be considered advantageous.
The textile fabric—with the features already mentioned and manufactured as already described—can be used, for example, as a vehicle tarpaulin, most preferably as a truck tarpaulin, as a packaging tarpaulin, as a tend tarpaulin cloth, as an inflatable boat, as a container, preferably as a flexible container, or as a bag.
The textile fabric can be used, for example, in the fields of architecture, advertising, visual protection, sheathing and/or temporary weather protection. The possible uses of the textile fabric are particularly wide since the textile fabric is particularly easy to process and the environmental compatibility is particularly high. For example, the textile fabric can also be used in the food sector as, for example, food packaging or food storage containers. Here, it is particularly important that the packaging material does not release any harmful substances into the food. Nevertheless, the packaging must protect the food from loss of flavour or prevent damage during transport. The use of the textile fabric in the field of medical technology, for example, as part of a moisture-repellent mattress cover, is also conceivable due to the improved skin-friendliness.
Yet another object of the present invention relates to a foil product manufactured at least in part from the textile fabric. The foil product has at least one weld seam that was manufactured by high-frequency welding and that is located in the area of the textile fabric in the foil product. Preferably, the foil product consists entirely of the textile fabric. A foil product should be understood to mean any structure that consists of at least a flexible and thin-walled material. The foil product can have a two- or three-dimensional shape.
The invention will be explained in more detail with reference to the following figures.
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| Number | Date | Country | Kind |
|---|---|---|---|
| 20215027.2 | Dec 2020 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/085877 | 12/15/2021 | WO |
