"RECYCLABLE COATED FABRIC, BASED ON POLYOLEFIN MATERIALS,

FOR USE AS DIGITAL PRINTING MEDIA"

The present invention consists in a fabric made with polypropylene (PP) , or other polyolefinic and/or thermoplastic yarns/fibres, directly coated with one or more layers of aqueous dispersions based on polyolefins ;

State of the art The technology of coating (direct or transfer) was, since its beginning, associated with Poly Vinyl Chloride (PVC) plastisols. The use of this technology was afterwards enlarged first for Polyurethane (PU) dispersions and then to Acrylic dispersions. The use of polyolefin aqueous dispersions in conventional coating equipments is still unknown.

The market of coated fabrics to be used as a support/media in digital printing, mainly in publicity both for indoor and outdoor, is nowadays dominated by solutions consisting in a polyester (PES) fabric, coated with PVC plastisols. The referred coated fabrics, based on PES/PVC are multi-material solutions, fact that limits its own recyclability . Brief Description of the f gures :

This description deals with the figures in annex that, with no limitative meaning, represent the following:

Figure 1: Constitution of the final coated product;

Figure 2: Scheme of the coating process; Figure 3: Flowchart of the invention.

Detailed description of the invention:

The present invention deals with a recyclable- coated fabric, based on polyolefin, for using as a media in digital printing applications, mainly in publicity both for indoor and outdoor. Concretely, the invention consists in a woven fabric made with polypropylene (PP) or other polyolefinic and/or thermoplastic yarn/fiber, directly coated with one or more layers of aqueous dispersions based on polyolefins.

The polyolefin aqueous dispersions have been optimised in order to find the intended and suitable characteristics: incorporation by agitation of fillers, pigments, processing aid additives, among others.

Direct coating technology was, and still is, associated to the industry of PVC plastisols. During the development of the reported invention, the suitable studies and adjustments were done in order to adapt the technology to the new dispersions.

The new coated fabric can be produced up to 5m wide, and has different weights depending on the construction of the fabric and/or the number of dispersion coated layers. Can also be produced in a semi-transparent, normal or opaque version. The coating can be applied by roll, knife on air, knife over roll, impregnation and other coating processes suitable for the purpose.

As well known, the polyolefins (or products based on polyolefins) are recognized by its low surface energy, which influences the adhesion properties of the surface and prejudice its wet-ability. To solve this limitation, and increase the surface energy of the polyolefins, it's recurrent to use complex, expensive and temporary technologies, as, for example, Corona discharge, Plasma treatment, among others.

In this invention, a combination of a primer and a lacquer was applied in the surface of the coated fabric: the primer consists in a aqueous dispersion based on a modified polyolefin that increases adhesion properties of the polyolefin coated surface, preparing it to the application of the lacquer; The lacquer consists in a aqueous polymeric dispersion, and can be applied using a engraved roll (for example 1000 points rolls), or any other system suitable for lacquer application. Figure 1 shows the different layers that constitute the final coated fabric, i.e., the textile support (1), the coating layer(s) (2) and the finishing layer (3) used to optimise its surface.

According the Figure 2, that describes the main stages of the coating process, the process begins with the application of the first layer of the polyolefin based dispersion on top of the polypropylene fabric, followed by a pre-drying in a oven; If desirable additional layers of coated can be applied, followed by drying and fusion in a oven. Finally occurs the finishing of the surface, consisting in the application of the system primer+lacquer, in order to obtain the suitable surface energy for digital printing .

The final coated fabric was, then, successfully tested with different digital printing inks and technologies, including UV curing inks, solvent and eco- solvent based inks, among other, with no need to additional surface treatments.

The materials used in the support and in the coating are both polyolefins based, fact that allows and enhance the recyclability of the final product. To evaluate this recyclability, the coated fabric results from this invention was triturated and re-processed by extrusion and injection moulding, using a typical polypropylene processing profile, without showing any limitation or problems. So, in the end of its useful-life this coated fabrics can be converted in new plastics products, obtained by extrusion, injection moulding and other plastic processing technologies, closing in this way the recycling cycle.

The flowchart illustrated in Figure 3 schematises all the activities of the reported invention.