FR2823357A1 - Flexible screen for building, has thin layer of fiber on one face of non-woven fabric, whose visible surface provides permeable layer to receive print - Google Patents

Abstract

One of the faces of a non-woven fabric is provided with a thin layer of fibers. The visible surface of the fibers is increased in order to provide a permeable layer to receive a print.

Description

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Field of the invention
The present invention relates to a screen formed by a flexible stretched surface, in particular for an outdoor installation, comprising a nonwoven sheet provided with a print.

Prior art
A screen of the type defined above is already known, formed of a sheet of nonwoven material, one face of which is provided with ink jet printing, marking the fibers without forming a film between the fibers.

 Such a screen is distinguished from screens formed by tarpaulins, that is to say textile surfaces consisting, in general of a polyester fabric provided with a waterproof coating of polyvinyl chloride (PVC), in that it has an air-impermeable surface.

 Indeed, according to certain regulations in force, surfaces such as tarpaulins or screens, installed outside, in front of buildings or in isolation, must allow a certain passage of the wind to reduce the forces exerted by the wind on these surfaces and the structures that support them.

 For this, the tarpaulins must have passages, generally in the form of U-shaped cutouts, constituting flaps free to open to clear the air passage orifices. According to certain regulations, the surface thus released in the total surface of the tarpaulin is less than 10% of the total surface of the tarpaulin.

 There are already screens with a decorative surface, formed by a non-woven sheet on which the decoration has been printed by monochrome or polychrome printing by ink jets.

 However, these known screens, formed from a nonwoven web, although more interesting than tarpaulins since requiring less resistant support structures for wind resistance, nevertheless have a certain number of drawbacks. First of all, the material itself being relatively porous, it functions as a filter and dirt builds up in the thickness of the nonwoven web.

 For example, it is known (according to document EP 0 704 315) to produce a printing medium made of a fibrous product, coated with porous particles having dimensions varying from 0.1 to 30 film and a surface layer made bohemian. The porosity of this layer is used to fix the ink. But such a layer for receiving the ink is not per-

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 airy or at least it is not enough to constitute an external screen.

 In addition, inkjet printing, which penetrates more or less and is distributed over a relatively large thickness of the nonwoven web, does not give an image as precise and clear as desired because some of the print droplets penetrate too deep in the nonwoven web to be noticeable from the outside. This can deteriorate the sharpness of an outline or the color which, produced by ink jets, results from the combination of primary shades.

 Finally, the projection by ink jet (s) being made in a certain direction of shooting, if the image is not seen from the same angle, due to this impression in thickness, the image seen will have no not the desired sharpness.

 Finally, these screens, when they have large surfaces, lack resistance and can deform or collapse.

Problem
The present invention aims to remedy these drawbacks and proposes to develop a decorative screen, intended to be installed especially outdoors, the quality of the graphic reproduction of the image is excellent, which resists soiling and offers sufficient mechanical strength when the screen is produced in the form of a large area.

Statement of the invention
To this end, the invention relates to a screen of the above type, characterized in that it is formed of a nonwoven web of which at least one face is provided in a thin thickness, of fibers which have been increased at least locally the visible surface to produce a permeable layer receiving the impression
The apparent surface of the fiber according to the present description is the surface of the section of the fiber by a plane substantially parallel to the face of the sheet or else the geometric projection of the outline of the fiber on a plane parallel to the face of the sheet. . This at least local increase in the apparent surface of certain fibers is achieved either by a local deformation of the fiber or by a local addition of material.

 According to a first embodiment, the at least local increase in the apparent surface of at least certain parts of fibers is carried out by a surface coating or by spraying a primed finish.

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 mant flakes, we can calendar this nonwoven web to form a thin surface layer whose apparent section of at least some fibers is increased by the flakes combined possibly crushing, welds between the fibers. This forms a permeable layer receiving the impression.

 This permeable layer of flakes can be produced by a thin, pasty, light and discontinuous application, scraped on the surface, or by a spraying of a product sufficiently thick to be deposited by forming flakes on the fibers, from the surface of the non-woven web, which only slightly decreases the permeability of the filtering surface. These two surface treatments (called primers) can consist of polyurethanes, melamine-formaldehyde or acrylic compounds, which are then generally polymerized hot.

 The screen according to the invention offers the advantage of being of sufficient permeability (of the order of 10% to 20%) to allow sufficient passage of air so that the result of the forces exerted on the screen and therefore on the structure supporting the screen is not excessive.

 The screen being crossed by a reduced air flow, dirt does not accumulate there as significantly as in a screen of a nonwoven sheet without flakes on the surface. In addition, the flakes constitute an apparent layer, which hides the interior of the nonwoven web so that even the particles of dirt which have penetrated into the nonwoven web do not appear on the surface.

 The importance of the flakes makes it possible to create a good matt surface for inscription or decoration giving a precise and clear decoration retaining all the original quality of the image and this whatever the angle from which the screen is seen. . The qualities of the screen are also ensured by the flatness of the surface formed by the surface coating, which is porous, so that, unlike the prior art, printing by ink jets is not done on free fibers, directed in three dimensions in the surface layer of the nonwoven web.

 On the contrary, the fibers, filled with flakes, remain in a relatively flat surface which forms the permeable decoration surface.

 According to another advantageous characteristic, the permeable surface layer is a coating or a spray, which can advantageously be calendered and / or polymerized hot.

 The coating is deposited in the form of a paste slightly penetrating into the nonwoven web to cling to the fibers and form

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une structure mince, discontinue, en flocons. L'aspersion, en entourant les fibres de surface d'apprêt et en les grossissant a sensiblement le même aspect et le même résultat.

a thin, discontinuous, flake structure. Spraying, surrounding the surface fibers of the primer and enlarging them has substantially the same appearance and the same result.

 According to another embodiment, the apparent section of the fibers of the surface layer or thin layer is increased by producing the sheet of nonwoven fibers, at least partly made of two-component fibers, welded, ensuring both reinforcement and opacity, that is to say the increase in the apparent surface, sufficient for printing. The two-component fibers have a core and a coating, the latter having a softening point lower than that of the core.

 The sheet is heated to the right temperature to obtain welds at the junction of the wires producing a solid three-dimensional structure. This nonwoven web can also be calendered hot to form a thin surface layer whose apparent cross-section of at least some fibers is increased by crushing combined with welds between the fibers which will have the effect of tightening the fibers and widening the coatings of fiber cores. This operation retains the necessary permeability of the entire screen.

 In the case of screens of large dimensions or intended to remain for a long time outside or in a strong wind, it is advantageous to integrate into the nonwoven web a flexible textile reinforcing element. This element can also be fixed on the rear face of the nonwoven web.

 According to another characteristic of the invention, the flexible reinforcing element may consist of a flexible and resistant grid, of a wide mesh fabric, open and resistant, or of a blocked mesh fabric, resistant or stitching lines.

 According to another characteristic of the invention, the flexible reinforcing element is produced in the structure of the nonwoven web itself, using the different resistances of the plastic fibers as well as their different degrees of melting. It is also possible to use two-component plastic fibers, the inner part or core of which has a melting point markedly higher than that of their peripheral coating. Such two-component fibers, judiciously chosen, arranged randomly forming a nonwoven web, can be welded together at their contact points, after having brought the assembly to the softening temperature of the coating. The fibers whose souls, are not altered by this temperature, are

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 welded after cooling by the solidified material of the coatings and then constitute a kind of mesh or resistant framework in the three dimensions of the nonwoven web. A nonwoven web can be produced only with two-component fibers. They can also be mixed with other fibers whose composition does not allow the welding with the material of the coatings of the two-component fibers. By the dosage and the choice of these different fibers, their length and their diameters, a nonwoven web is produced which is sufficiently resistant, opaque and breathable.

 According to the invention, the permeability of the assembly formed by the nonwoven web and of its permeable surface layer provided with the print, has an overall air permeability of the order of 10 to 20%.

 Although the screen according to the invention is generally visible simply by reflection of light on its front surface, it is also possible to produce translucent screens, backlit, in particular to form bright screens. In this case, it is advantageous to produce the screen by a nonwoven web having received a permeable surface treatment process on its two faces and possibly a flexible and resistant element in its median plane. The two faces of this screen can be provided with a plane symmetrical printing on the two sides, simultaneously, in a double-sided inkjet printing machine.

- la figure 9 montre une autre réalisation d'un écran avec une structure de renforcement interne constituée d'un réseau à trois dimensions de fibres bi-composants avec le premier procédé de traitement superficiel, drawings
The present invention will be described below using an embodiment shown in the accompanying drawings in which: FIGS. 1 to 3 are schematic sectional views of a screen known at three different magnifications, - Figures 4-6 are sections of a screen according to the first embodiment of the invention at three different magnifications, - Figure 7 shows another embodiment of a screen according to the invention with a flexible support resistant consisting of an integrated grid, - Figure 8 shows another embodiment of a screen with a reinforcement grid on the rear surface,

FIG. 9 shows another embodiment of a screen with an internal reinforcement structure constituted by a three-dimensional network of bi-component fibers with the first surface treatment method,

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 - Figure 10 shows the production of a screen with an internal reinforcement structure consisting of a three-dimensional network of two-component fibers with the second surface treatment method.

Description of embodiments
According to FIGS. 1 to 3, a known screen, represented diagrammatically in section at three different magnification scales (x 20, x80, x350) is formed from a nonwoven sheet 1 in which we have produced, from face 2 , the impression of a decoration by projection of ink jets.

This projection results in droplets 3 attached to the fibers 4 without, however, thanks to the fluidity of the ink, forming a veil between the fibers.

 It can be seen that the impression formed by the droplets 3 on the fibers 4 extends over a certain depth P, significant relative to the overall thickness E of the nonwoven web 1.

 The printing direction is given by the arrow C. This direction of the ink jet (s) is generally perpendicular to the surface of the nonwoven web. It can also be done at a different angle. However, due to this orientation of the ink jets and the penetration of the droplets, when looking in a direction D different from the printing direction C, certain printing droplets no longer appear because they are hidden by fibers. In addition, as a result of their deviation inside the fiber layer, certain ink droplets become invisible from the outside regardless of the direction D ′ in which one looks at the visible face of the web.

 Image clarity is also deteriorated when viewed in a direction other than the printing direction. This is all the more marked since the front surface of the sheet (like its rear surface moreover) is not smooth but leaves fibers distributed randomly in all directions relative to the theoretical surface represented by the plan of the tablecloth.

 Figures 4 to 6 schematically show three sections at three different magnification scales (x20, x80, x350) of a screen according to the first surface treatment method of the invention.

 The screen 10 is formed of a nonwoven web 11, the front face 12 of which is provided, over a thin thickness, with a permeable layer 13 intended to receive the impression. The permeable surface layer 13 is formed by a pasty surface coating or a spray of liquid finish, which penetrates into the fibers 110 at the surface of the nonwoven web 11.

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The permeable surface layer 13 consists of flakes 131 attached to a few fibers 110 as shown by the enlargements of FIGS. 5,6, leaving gaps between the flakes.

These flakes 131 are distributed practically on the surface. They also ensure a certain flatness on the surface by freezing the non-woven fibers, sometimes flattened on the surface after calendering.

 In the case of coating or spraying, there remain gaps between the flakes ensuring the permeability of the layer.

 The permeability of the screen formed by the nonwoven web and the permeable surface layer of the flakes is of the order of 10 to 20% in the sense of the air permeability of a screen according to the definition given above. .

 After the support has been produced, the decoration is printed with ink jets. The ink droplets 14 catch on the flakes 131 of the surface layer 13 either on the surface or that they penetrate slightly in the intervals. But the thickness (e) of this layer 13 being very small, the droplets 14 cannot penetrate deeply and above all they do not risk following random paths. Under these conditions, the sharpness of the image is the same regardless of the direction (D) in which we look at the surface 12 of the surface layer 13. Even if the ink droplets penetrate to a certain depth of the layer su - perficiel 13, the droplets which must combine to form compound colors, will give precisely the desired colors.

 FIG. 7 schematically shows the section of a screen 20 according to the invention at 20 × magnification, the non-woven part 21 of which is provided with a reinforcement grid 25: this grid consists of wires or strands 251 and 252 in two directions orthogonal. This flexible grid is integrated in the nonwoven web 21. The other elements of this screen are the same as in the first embodiment. The front face 22 of the nonwoven ply 21 is provided with a permeable surface layer 23 formed by a coating or spraying giving flakes 231; the set includes a decoration formed by ink droplets hanging on the flakes 231.

 FIG. 8 shows another embodiment of a screen 30 formed of a nonwoven web 31 the front face of which is provided with a permeable surface coating 33 formed of flakes 331 locally increasing the apparent surface of the fibers to produce on a thin thickness, the permeable layer receiving the ink droplets of the decoration.

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 This thin thickness of the web (front face) can be calendered. The rear face of the ply is provided with a reinforcement grid 35 formed of flexible wires applied and secured to the rear surface without being integrated into the mass.

 FIG. 9 schematically shows the section of a screen 40 according to the invention, at x80 magnification, the nonwoven web 41 of which consists of single component filling fibers 410 mixed with a resistant structure in the three dimensions of the space, of two-component fibers 420. The resistant cores 440 of the fibers are welded at their contact points 441 by the material 442 of their sheath, the melting point of which is lower than that of the cores and of the filling fibers. The other elements of this screen are the same as in the other embodiments; the front face 42 of the nonwoven web 40 is provided with a thin permeable layer formed by a coating or a spray giving flakes 431; the decoration is produced by ink droplets 14 projected onto the upper part of the flakes 431.

 The same FIG. 9 can also illustrate an example of a screen, the nonwoven web 41 of which consists solely of two-component fibers 420 formed from a core 440 and a sheath 442 made of different plastics at least by their point of fusion, that of the sheath being less than that of the core.

 In the thin surface layer, the fibers are welded at their contact points 441 by the material 442 constituting their sheath whose melting point is lower than that of the cores. The treatment of the surface of the sheet can be carried out hot, by exposure to radiation, blowing of hot air or by calendering.

 This surface treatment not only performs the welding of some of the fibers, at the surface with the mechanical advantages already described, but also produces a certain spreading of the fibers in certain places, that is to say a local increase in their apparent surface, achieving the thin layer receiving the impression, without practically reducing the permeability of the sheet.

 FIG. 10 schematically shows the section of a screen 40 according to the invention at 80 × magnification. As in FIG. 9, the nonwoven web consists of single component filling fibers 410 mixed with a resistant structure in three dimensions space, of two-component fibers 420. The resistant cores 440 of the fibers are welded at their contact points 441 by the material 442

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 of their sheath, the melting point of which is lower than that of the cores and of the filling fibers. The surface treatment is obtained by hot calendering which increases the apparent surface of at least some fibers, that is to say the surfaces for receiving and fixing ink jet prints by slightly crushing the coatings. fibers softened by the effect of heat. The fibers can also have a variable melting point in their thickness, i.e. have a low melting point on the outside and a gradual or discontinuous increase in the melting temperature (melting point) towards the center of the fiber section.

 These enlarged surfaces 542 create the surfaces for receiving the prints, like the flakes 131 in FIGS. 4 to 6. The bringing together of the surface fibers by calendering also ensures the increase in the ink reception surfaces. Always keeping a 10 to 20% air permeability.

 Finally, another embodiment of a screen intended to be seen by transparency, is a double-sided screen such as that of FIG. 4,7 or 9 but which would also have received a flexible and permeable coating of flakes on its face back.

 It is also possible to produce a double-sided screen such as that of FIG. 10 but also calendered hot on its 2 faces, so as to also give only one image as in the previous case.

 By making a decoration on both sides on such a support, the decoration, intended to be illuminated by transparency, can be produced symmetrically on its two sides to give only one image when looking at the face. illuminated by transparency by a light source directed against the other face.

 Such a symmetrical screen, with respect to the median plane of the support, is extremely easy to produce by printing by ink jets since it is very schematically sufficient to reverse one of the polarities of the printing signals. Thanks to the invention, much more faithful and better contrasted bright images are obtained.

 The permeability of the screen, reduced to the level necessary to allow the passage of the wind under the conditions defined by certain regulations, offers the advantage of being less than that of a nonwoven, untreated sheet, and thus retaining less of dirt. The screen according to the invention also absorbs less moisture since it has

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 much of it tends to run along the face with the smooth permeable layer. The sharpness of the images is improved considerably, eliminating any difficulty linked to parallax, to the disappearance of the ink droplets in the depths of the nonwoven web and the quality of the image remains preserved whatever the angle from which one look at the surface of the tablecloth.

Claims (1)

 CLAIMS 1) Screen formed from a stretched flexible surface, in particular for an outdoor installation, bearing an imprint, characterized in that it is formed from a nonwoven web (11) of which at least one face is provided in a thin thickness (13) of fibers, the apparent surface of which has been increased at least locally (131,331, 431,542) to produce an air-permeable layer receiving the impression (14).  2) Screen according to claim 1, characterized in that the at least local increase in the apparent surface of at least some parts of fibers is carried out by a surface coating or a sprinkling of primer forming flakes (131).  3) Screen according to claim 2, characterized in that the coating (13) or spraying is calendered and / or polymerized hot.  4) Screen according to claim 2, characterized in that the coating is deposited in the form of a paste slightly penetrating into the nonwoven web.  5) Screen according to claim 1, characterized in that the nonwoven web (41) formed at least partially in the thin surface layer by the two-component fibers (420) having a core (440) and a sheath (442 ), the melting point of the sheath being lower than that of the core, in order to increase the apparent surface (542) of at least certain parts of fibers by at least partial melting of these.  6) Screen according to claim 5, characterized in that the partial melting (442) of the sheath of certain fibers (440) is carried out by hot air, radiation or hot calendering, thus producing a partial and local fusion of the sheaths welding fibers together at their contact. <Desc / Clms Page number 12>  7) Screen according to claim 1, characterized in that the nonwoven web (21,31) comprises a flexible element (25,35) of reinforcement integrated in the thickness of the nonwoven web (21, 31).  8) Screen according to claim 1, characterized in that the nonwoven web (31) comprises a flexible reinforcing element (35) secured to the rear face of the web (31).  9) Screen according to any one of claims 7 or 8, characterized in that the flexible reinforcing element (25,35) is a textile grid, a loose fabric, a blocked mesh fabric or stitching lines.  10) Screen according to claim 1, characterized in that the nonwoven web (11,21, 31), provided with its permeable layer (13,23, 33,43), has an overall permeability of the order of 10 to 20%.  11) Screen intended to be lit from behind, formed of a nonwoven sheet according to claims 1 to 6, characterized in that it comprises a single layer of nonwoven with a surface treatment on each of its faces and a symmetrical print hangs on both sides.