Planar textile structure with coating

Abstract

The invention relates to a planar textile structure comprising a support layer consisting at least of polyethylene and / or polyester fibers. On at least one surface of the support layer a surface coating is applied, wherein the surface coating consists of at least one polymer mixture having a mixture of at least one polyethylene (PE) and polyethylene-vinyl acetate (PEVA), the content of polyethylene-vinyl acetate in the polymer mixture being at least equal to 40 wt.%, based on the total weight of the polymer mixture. The invention also relates to the production of such a planar textile structure, the use of the planar textile structure, and a foil product made of the planar textile structure.

Description

[0001] This invention relates to a fabric with a surface coating.

[0002] Coated textiles are generally well-known. Polyvinyl chloride (PVC) is frequently used as a coating material. For example, in document DE 19926732, knitted fabrics made of polyester fibers are coated with PVC using a reverse method. Furthermore, from document WO2012 / 022626, it is known that a coating material made of polyolefin homopolymer or polyolefin copolymer is used to coat a support material. Document CN 110725135 discloses a fabric in which a coating made from a combination of polyethylene and ethylene-vinyl acetate copolymer is used. In the embodiments of this document, the content of ethylene-vinyl acetate copolymer is in the range of up to 25% by weight, and the use of this fabric is considered primarily in the field of household goods. Document US 3,660,150 also describes a fabric with a surface coating. This surface coating may also consist of a mixture of polyethylene and ethylene-vinyl acetate copolymer.

[0003] WO 2018 / 104101 also discloses a fabric having a support layer made of polyethylene, for example, wherein the fabric has a coating made of a mixture of polyethylene and polyethylene-vinyl acetate on at least one surface.

[0004] The fabric of WO 2018 / 104101 is a pile fabric coated by spray impregnation, used for automotive wheel covers to suppress noise, but also exhibits good stain and ice resistance.

[0005] One known drawback of coated textiles is that, if, for example, polyvinyl chloride (PVC) is used as the coating material, toxic decomposition products are often generated when the textiles are incinerated or disposed of as waste. A disadvantage of using polyolefins as the coating material is that further processing of such coated textiles (e.g., painting or providing the finished product) is often very complex.

[0006] Therefore, the object of the present invention is to provide a coated textile that has at least good coating environmental compatibility, is easy to process, and can be well adapted to different applications.

[0007] This objective is achieved through a fabric having a woven support layer, wherein the support layer consists of at least polyethylene and / or polyester fibers. A surface coating is applied to at least one surface of the support layer, wherein the surface coating consists of at least one polymer mixture, wherein the polymer mixture comprises at least one mixture of polyethylene (PE) and polyethylene-vinyl acetate (PEVA). Based on the total weight of the polymer mixture, the content of polyethylene-vinyl acetate in the polymer mixture is at least 40% by weight. By using the aforementioned weight content of polyethylene-vinyl acetate in the coating material, the coating material possesses surprisingly novel properties that are not present in pure polyethylene coating materials or polymer mixtures with a lower content of polyethylene-vinyl acetate. For example, the fabric of the present invention can be further processed with paints that do not adhere well or only poorly to pure PE coatings. Furthermore, the surface coating of the fabric according to the present invention is more weather-resistant than PVC coatings and emits fewer pollutants. Moreover, it is particularly advantageous that the fabric with the aforementioned polyethylene-vinyl acetate content can be further processed by high-frequency welding, resulting in easier further processing of the fabric and enabling new uses for the fabric.

[0008] Furthermore, the surface of the woven support layer coated in this way is very smooth, thus allowing for simple and diverse printing. Therefore, the fabric according to the invention is particularly suitable, for example, as a tarpaulin or covering for trucks, or as any kind of woven fabric.

[0009] A surface coating consisting of at least one polymer mixture should be understood as being composed entirely of or primarily of a polymer mixture.

[0010] In one embodiment, the surface coating consists of a polymer mixture of more than 70 wt%, more than 80 wt%, more than 90 wt%, or 100 wt%, depending on the total weight of the surface coating.

[0011] In this invention, polyethylene-vinyl acetate is abbreviated as PEVA, polyethylene as PE, and vinyl acetate as VA. Polyvinyl chloride is abbreviated as PVC.

[0012] In one embodiment, based on the total weight of the polymer mixture, the PEVA content in the polymer mixture is 45% by weight, preferably 49% by weight, more preferably 50% by weight, further preferably 55% by weight, and even more preferably 60% by weight.

[0013] In one embodiment of the fabric, the polyethylene-vinyl acetate (VA) content in the polymer blend is 5-50% by weight, preferably 10-40% by weight, more preferably 15-30% by weight, and even more preferably 20-25% by weight, based on the weight of the polymer blend. Advantageously, the fabric can be processed from a VA content of about 10% by weight (based on the total weight of the polymer blend) by high-frequency welding, which is not possible with pure PE coating. Therefore, there are various options for further processing of the fabric, ultimately expanding its applications. Furthermore, the approximately 10% by weight VA content in the polymer blend imparts elasticity and softness to the surface coating or fabric, as found in soft polyvinyl chloride, for example. In one embodiment, the VA content in the polymer blend is from 15% by weight to over 40% by weight, based on the total weight of the VA. In one embodiment, if the VA content exceeds 40% by weight, the PEVA material in the polymer blend becomes rubbery, thus allowing for use in applications such as bags, foil, or footwear (especially soles).

[0014] In one embodiment, in addition to PEVA and PE, the polymer mixture also contains polypropylene.

[0015] This polymer blend comprises polyethylene and polyethylene-vinyl acetate, which allows for certain properties in terms of coating processability. Polyethylene has a melting point of 135-145°C, meaning it can be easily processed on melt calendering systems. The melting point of polyethylene-vinyl acetate is variable, depending on the vinyl acetate content. For example, a polyethylene-vinyl acetate blend with approximately 7% by weight has a melting point of approximately 104°C, while a blend with 28% by weight has a melting point of approximately 70°C. By using a blend of PE and PEVA within the aforementioned range, processing on conventional calendering systems and pre-extrusion steps are possible. Processing pure PEVA on conventional calendering systems can be difficult.

[0016] By adding PEVA to polyethylene, the hybrid properties of the two polymers can be obtained, such as high-frequency weldability or improved weather resistance, as well as the lower tendency of PEVA to form stress cracks. PE itself has good chemical resistance.

[0017] As previously mentioned, the fabric and its surface coating can be advantageously heated (high-frequency welding) using high-frequency energy in the form of an electromagnetic field. Under heating and pressure, the fabric's surface coating begins to melt, allowing it to bond with other parts of the fabric, with other fabrics of the same or different types (fusible), or with completely different materials (such as a coating of PE). No heat is supplied from the outside during this process, meaning fewer occupational safety precautions are required. The heat is generated separately in the fabric and its surface coating, making it particularly effective. During cooling (e.g., under constant pressure), the different materials fuse together, forming a weld. This allows for a very strong bond without affecting the fabric's weather resistance, such as its impermeability. Another advantage of this fabric bonding method is that the process does not generate large amounts of harmful vapors or combustion residues over a large area. Depending on the fibers used in the support layer, high-frequency welding can also cause the fibers of the support layer to completely or at least partially melt. The partially or completely melted fibers within the seam can provide a degree of stability to the seam, for example, which is beneficial for fabric shaping.

[0018] Fabrics can also be advantageously joined to other materials using other (conventional) welding processes. For example, fabrics can be joined to other fabrics coated with polyethylene and / or polypropylene by hot air welding. When a fabric is hot-air welded to another fabric with a polyethylene coating, a tack value exceeding approximately 50 N / cm can be measured without edge waviness. Similarly, when a fabric is hot-air welded to another fabric with a polypropylene coating, a tack value exceeding approximately 50 N / cm can also be measured without edge waviness. In all cases, the tack value is determined using standard ISO 2411:2017 (EN ISO 2411:2017), which uses the second sample preparation method of that standard, and the values ​​measured in the machine direction (i.e., in the warp direction) are applied to the measurement of the test sample.

[0019] In one embodiment of the invention, the support layer is composed entirely of fibers made of polyethylene and / or polyester. In a preferred embodiment, the support layer is composed entirely of polyester fibers. "Completely composed" means that the support layer is composed of more than 80%, preferably more than 90%, and most preferably 100% of said fibers. In the case of a combination of polyethylene and polyester, the support layer is preferably composed of a yarn mixture of polyethylene and polyester fibers. For example, high-strength polyethylene fibers, such as those available under the trade names Dyneema (Fa. DSM BV) or Spectra (Fa. Honeywell International), can be used as polyethylene fibers. Fa. High-performance polyester fibers, for example, can be used as polyester fibers. A support layer composed of said fibers or mixtures of said fibers has the advantage of being easy to manufacture and adaptable to various technical requirements, such as the strength of the support layer, because a wide range of fiber types are available.

[0020] The term "fiber" should be understood to refer to both endless fibers and perennial or short fibers. These fibers can be either polyfilament yarns or monofilament yarns.

[0021] In one embodiment, the polyethylene content of the polymer mixture in the surface coating is less than 51% by weight, based on the total weight of the polymer mixture. In another embodiment, the polymer mixture, based on the total weight of the polymer mixture, consists of at least 95% by weight of a combination of polyethylene and polyethylene-vinyl acetate. In addition to the polymer mixture, the surface coating preferably contains less than 20% by weight, more preferably less than 15% by weight, even more preferably less than 10% by weight, and most preferably less than 5% by weight of other components—such as additives. The advantage of this surface coating is that the mixture of PE and PEVA combines the advantages of both substances without the disadvantages of each adversely affecting the surface coating. For example, the surface coating exhibits good long-term stability due to the PE contained therein. PEVA is particularly robust, thus increasing the lifespan of the surface coating, especially in terms of its mechanical properties. Furthermore, PEVA forms the basis for fabrics to be processed by high-frequency welding and improves the paintability of the surface coating. Furthermore, in this surface coating made from the aforementioned combination of PE and PEVA, plasticizers or halogen-containing substances can be omitted. This prevents the diffusion of halogen-containing chemicals or plasticizer components to the surface of the coating and the risk of undesirable interactions there, such as with paint. This makes the fabric more environmentally friendly, maintaining stable chemical properties even over its long lifespan. Another advantage of choosing polymer blends for the surface coating is that, due to the elimination of plasticizers, the fabric is more skin-friendly than PVC-coated fabrics with plasticizers. In particular, this simplifies the processing of such skin-friendly fabrics by manufacturers, allowing them to be used for new applications, such as those involving frequent skin contact.

[0022] In this embodiment of the fabric, the support layer is a woven fabric or a gypsum woven fabric. The support layer is most preferably a woven fabric with a twill, plain, Panamax, or satin weave. The support material can be single-layered or multi-layered, wherein the support layer can have a combination of the aforementioned single-layered or multi-layered structures. For example, the support layer can be a multi-layered structure, consisting of at least two woven fabric layers or one woven fabric layer and one gypsum woven fabric layer.

[0023] In one embodiment, a surface coating on at least one surface of the support layer is applied to the entire surface. "Entire surface" means that after coating, the surface of the support layer essentially no longer has any uncoated areas. When using, for example, a very open mesh as the support layer, applying a coating to the entire surface also means that while the mesh has no uncoated areas on the surface to be coated, the gaps between the meshes remain free. Neither the material of the support layer nor the material of the coating is present in the gaps. The fabric preferably has a coating on both surfaces of the support layer, covering the entire surface. Particularly preferred is that the coating on both surfaces of the support layer is done with the same surface coating. However, it is also conceivable to apply different surface coating materials. In one embodiment, by coating both surfaces, strips made of the coating material are formed within the support layer, wherein the strips connect the two surface coatings to each other. In another embodiment of the fabric, no or only a small number of strips made of the coating material are formed within the support layer, wherein the strips result in no or only a small connection between the two surface coatings of the support layer.

[0024] In one embodiment, the coating of the support layer with the polymer mixture is done integrally. Here, integrally means that the coating material (polymer mixture) is applied to the support material essentially as a coherent block of coating, for example, as a melt or foil, rather than, for example, as sprayed particles, and then forming a coating over the entire surface. An advantage of integral coating, for example, is that the surface of the coating is particularly smooth, and therefore, the surface quality is very high. Thus, for example, better printability is also possible.

[0025] In another preferred embodiment, the polymer mixture of the surface coating is free of polyvinyl chloride (PVC). In this invention, "free of PVC" means, based on the total weight of the polymer mixture, that the polymer mixture contains less than 1% PVC by weight, most preferably 0% by weight. In another preferred embodiment, the surface coating is free of PVC, again meaning, based on the total weight of the surface coating, that the surface coating contains less than 1% PVC by weight, most preferably 0% by weight. In this case, neither the polymer mixture nor the surface coating contains PVC—as a separate component from the polymer mixture. Without the use of PVC, the manufacture and recycling of fabrics are significantly more environmentally friendly, and the skin-friendliness of the fabric is also improved. For example, the highly toxic gas vinyl chloride is not used in the production of PE and PEVA.

[0026] In one exemplary embodiment, the adhesive strength of at least two pieces of fabric welded together by high-frequency welding is at least 8 N / cm. Preferably, the adhesive strength of at least two pieces of fabric welded together by high-frequency welding is about 12 N / cm, more preferably about 15 N / cm, more 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 adhesive strength value is determined according to standard ISO 2411:2017 (ENISO 2411:2017), wherein the second sample preparation method of the standard is used, and the value measured in the machine direction (i.e., in the warp direction) is applied to the measurement of the test sample.

[0027] Another object of the present invention relates to a method of manufacturing a fabric having the characteristics described above. In this method, a surface coating is applied to at least one surface of a support layer having at least polyethylene and / or polyester fibers by means of a melt calender. For coating the surface, a surface coating consisting of at least one polymer mixture is selected, wherein the polymer mixture has at least one polyethylene and a mixture of polyethylene-vinyl acetate. Based on the total weight of the polymer mixture, the polymer mixture has more than 40% by weight of polyethylene-vinyl acetate. It goes without saying that the surface coating is present in melt form during the manufacturing process and is processed into a uniform layer in a correspondingly flowable manner (therefore there is no foil of surface coating material stacked by rollers, nor is there spraying by means of matrix droplets or powder). 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.

[0028] During fabric manufacturing, the support layer is preferably coated on its upper side with a width exceeding three meters in a single process step using a melt calender. Thus, a surface coating web with a width of at least three meters is formed on the support layer in a single coating operation. This allows for the advantageous manufacture of larger fabrics with a continuous coating material web. Advantageously, overlapping areas of the coating material are not formed in this case, or are less frequent when the width exceeds three meters. In an advantageous manner, the printability of the fabric is thus further improved, because not only does the woven support layer achieve a uniform coating, but the coating itself also achieves a special surface quality.

[0029] Another object of the invention relates to the use of a fabric manufactured as described above and having the characteristics described above. This fabric can be further processed by high-frequency welding for shaping and fixing. For example, truck tarpaulins, bags, containers, etc., can be manufactured from this fabric by high-frequency welding; the fabric is preferably present as a mesh material. The fabric is preferably formed and / or fixed entirely by high-frequency welding. Of course, the fabric can also be processed using alternative welding methods, such as hot air methods. Advantageously, when using alternative welding methods (different from the processing of textiles containing PVC in the coating), no toxic fumes are generated during the welding process, thus requiring only less stringent occupational safety measures during processing.

[0030] The surface coating of the fabric with the above characteristics can be varnished; for example, in this case, PVC-free or PVC-containing varnishes are preferred. Surprisingly, despite the significant polyethylene content in the fabric's surface coating, it can be coated or varnished with either PVC-free or PVC-containing varnishes. This is not possible with surface coatings that do not contain EVA, or only possible under difficult circumstances, or only possible by using more additional adhesion promoters, or, for example, only after surface pretreatment (e.g., corona treatment) before coating. However, for special varnishes, the use of adhesion promoters is still possible, and corona treatment can be performed if necessary. Furthermore, the preparation of the fabric before varnishing appears to be shortened or simplified. Using a smaller amount of adhesion promoter can also be considered advantageous.

[0031] The fabric—having the features already mentioned and manufactured in the manner already described—can be used, for example, as a vehicle tarpaulin, most preferably as a truck tarpaulin, as a packaging tarpaulin, as a care tarpaulin, as an inflatable boat, as a container, preferably as a flexible container, or as a bag.

[0032] This fabric can be used in various fields, such as construction, advertising, visual protection, sheathing, and / or temporary weather protection. Its potential applications are particularly wide-ranging due to its ease of processing and high environmental compatibility. For example, it can also be used in the food industry, such as as food packaging or food storage containers. Here, it is especially important that the packaging material does not release any harmful substances into the food. However, the packaging must protect the food from loss of flavor or prevent damage during transportation. The use of this fabric in the medical technology field, for example, as part of a moisture-proof mattress cover, is also conceivable due to its improved skin-friendliness.

[0033] Another object of the invention relates to a foil product at least partially made of fabric. The foil product has at least one weld seam, which is manufactured by high-frequency welding and located in a region of the fabric within the foil product. Preferably, the foil product is entirely composed of fabric. The foil product should be understood as any structure composed at least of a flexible, thin-walled material. The foil product can have a two-dimensional or three-dimensional shape.

[0034] The present invention will be explained in more detail with reference to the following figures.

[0035] Figure 1 , 2 And 3a) and 3b) show photographs of the fabrics, wherein sample 1 is coated with a pure PE-polymer mixture and sample 2 is coated with a polymer mixture made of a mixture of polyethylene and ethylene-vinyl acetate copolymer. Figure 4a and 4b Photographs of samples 3 and 4 are shown respectively. In sample 3, a coated fabric and another fabric with a coating made of polypropylene were welded together with hot air, while sample 4 shows a fabric welded together with another fabric with a polyethylene coating.

[0036] Figure 1 Samples 1 and 2 are shown, where the support material is fabric in both cases. Due to the use of a woven support layer, in... Figure 1 As can be clearly seen, a flat and uniform surface is formed after coating, which makes it easy to print on.

[0037] exist Figure 2 In this process, two identical sample pieces (i.e., samples made of the same material) were placed one on top of the other and treated with thermal stress (hot air). It can be clearly seen that in both sample 1 and sample 2, the coating material locally melted and adhered together, forming a seam. Therefore, Figure 2 It is clearly shown that both samples 1 and 2 can be thermally welded. As a result of the welding, an adhesion value of 8 to 70 N / cm can be advantageously achieved between the textiles, preferably 12 to 60 N / cm, most preferably 15 to 40 N / cm, and even more preferably 20 to 25 N / cm. The adhesion value is determined according to standard ISO 2411:2017 (EN ISO 2411:2017), wherein the second sample preparation method of the standard is used, and the value measured in the machine direction (i.e., in the warp direction) is applied to the measurement of the test sample.

[0038] exist Figure 3a and Figure 3bIn the images, two identical sample pieces were placed one on top of the other and processed by high-frequency welding. It is clearly visible in both images that only in sample 2 did the coating material partially melt and connect with the other coating to form a seam. In sample 1, no such connection occurred, so the cohesive strength of the two sample 1 pieces cannot be determined. The difference between sample 1 and sample 2 is that pure PE compound (sample 1) can be thermally welded (e.g., by hot air welding), just like the PE / EVA in sample 2, but only sample 2 can also be processed by high-frequency welding.

[0039] exist Figure 4a In this example, sample 3 is formed from a fabric and another fabric with a coating made of polypropylene. Through hot air welding, an adhesion strength exceeding 50 N / cm was achieved without edge waviness. Figure 4b In this process, the sample is formed from a fabric and another fabric with a coating made of polyethylene. Here, also relating to the fabric according to the invention, the connection can be achieved by hot air welding, with an adhesion value of at least 50 N / cm without producing edge waviness. Here, the adhesion value is also determined using standard ISO 2411:2017 (EN ISO 2411:2017), wherein the second sample preparation method in that standard should be used, and the value measured in the machine direction (i.e., in the warp direction) should be applied to the measurement of the test sample.

Claims

1. Fabric, wherein the fabric has a woven support layer, which consists at least of polyethylene and / or polyester fibers, wherein on at least one surface of the support layer a surface coating is applied, which consists of at least one polymer mixture, wherein the polymer mixture has a mixture of at least one polyethylene and polyethylene-vinyl acetate, characterized in that, The polymer mixture contains more than 40% by weight of polyethylene-vinyl acetate, based on the total weight of the polymer mixture.

2. The fabric according to claim 1, wherein the polyethylene-vinyl acetate in the polymer mixture contains 10-40% by weight of vinyl acetate, based on the weight of the polymer mixture.

3. The fabric of claim 1, wherein the polymer mixture has less than 51% by weight of polyethylene, based on the total weight of the polymer mixture.

4. The fabric of claim 2, wherein the polymer mixture has less than 51% by weight of polyethylene, based on the total weight of the polymer mixture.

5. The fabric according to any one of claims 1-4, wherein the support layer is composed entirely of fibers made of polyethylene and / or polyester.

6. The fabric according to any one of claims 1-4, wherein a surface coating on at least one surface of the support layer is applied over the entire surface.

7. The fabric of claim 5, wherein a surface coating on at least one surface of the support layer is applied over the entire surface.

8. The fabric according to any one of claims 1-4, wherein the polymer mixture is free of polyvinyl chloride.

9. The fabric of claim 7, wherein the polymer mixture is free of polyvinyl chloride.

10. A method of coating a fabric according to any one of claims 1 to 9, wherein a surface coating is applied by a melt calender to at least one surface of a support layer composed of at least polyethylene and / or polyester fibers, said surface coating being composed of a polymer mixture having at least one mixture of polyethylene and polyethylene-vinyl acetate, characterized in that, The polymer mixture contains more than 40% by weight of polyethylene-vinyl acetate, based on the total weight of the polymer mixture.

11. The method of claim 10, wherein the support layer is coated over a width of more than 3 meters across the entire surface in one process step.

12. Use of the fabric according to any one of claims 1 to 9 for shaping and fixing by high-frequency welding.

13. Use of the fabric according to any one of claims 1 to 9 for coating a surface with a varnish that is free of or contains polyvinyl chloride.

14. Use of the fabric according to any one of claims 1 to 9 as a vehicle waterproofing tarpaulin.

15. Use of the fabric according to any one of claims 1 to 9 as a packaging waterproof tarpaulin, a care waterproof tarpaulin, an inflatable boat, a flexible container or a bag.

16. Use of the fabric according to any one of claims 1 to 9 in the fields of construction, advertising, visual protection, sheathing and / or temporary weather protection.

17. A foil product made from a fabric according to any one of claims 1 to 9, wherein the foil product has at least one weld seam formed by high-frequency welding.

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