FR2931388A1 - Dry cold transfer for e.g. vehicle body, has polyurethane layer forming film extended to cover pattern, while defining component size during transfer utilization, and transfer layer possessing thickness larger than specific micrometers - Google Patents

Abstract

The transfer has a transparent polyurethane layer and an adhesive transfer layer (15) adapted so that the polyurethane layer is detached from a printing support sheet (10) when the transfer is applied on a rigid surface (17) of a substrate (16). The polyurethane layer forms a single piece continuous transparent polyurethane film (11) that is extended to cover a printed marking pattern (12), while defining size of a unique and single piece transferred component (20) during utilization of the transfer. The film and the layer (15) have thicknesses larger than 30 and 40 micrometers, respectively. The support sheet is formed of material that is chosen from a group comprising paper, PVC, polypropylene or non woven material. An independent claim is also included for a method for marking a surface of a substrate.

Description

The invention relates to a cold dry transfer for the application of at least one marking pattern on a surface of the same material. BACKGROUND OF THE INVENTION a substrate - in particular a rigid surface such as a vehicle body, aircraft cabin, showcases, It extends to a method of marking a substrate surface with the aid of such a dry transfer to cold.

Cold dry transfer means, throughout the text, a ready-to-use device comprising a support sheet bearing at least one marking pattern and making it possible to transfer each marking pattern onto a substrate surface to be marked without use. no liquid or heating. It should be noted in particular that a cold dry transfer is distinguished from so-called varnish transfers that require the use of varnish to perform the transfer operation, and reactivatable transfers that require, for this operation, the use solvents, water or heating means. A cold dry transfer is also distinguished from a self-adhesive label that is applied to a substrate by simple application and collages, without transfer operation.

Throughout the text, the term "marking pattern" designates one or more continuous or discontinuous visible graphic sign (s), joint (s) or disjoint (s), of any shape. Examples of a marking pattern are: a character, a group of characters, a letter, a group of letters, a logotype, a word, a group of words (text), an image, a group of words, 'images, a drawing, a group of drawings, a solid color (s) (continuous layer) ...; or a combination of such signs; or a regular repetition or not of such signs. FR 2781183 discloses a dry transferable decal comprising a support bearing distinct transferable patterns, each pattern being formed of a polyurethane varnish partially covering the support, a polyurethane ink applied to the varnish, and a polymer adhesive of solvent-phase acrylate covering the ink with an overflow that exactly matches that of the varnish. The varnish, the ink and the adhesive each have a thickness of approximately 10 m. Such a decal however proves in practice to have a largely insufficient resistance. It is fragile and likely to break. In addition, contrary to what this document indicates, it is actually not very resistant to ultraviolet, especially given the small thickness of the polyurethane varnish. In particular, the overflow of the unprotected adhesive by the ink is subjected to ultraviolet and yellows, which ends up producing an unsightly visible effect. Furthermore, the polyurethane varnish compositions used for producing such a decal are transparent ink-like compositions adapted to be printed in screen printing, and, in practice, are generally not compatible with modern polyurethane protective paints. used later to cover the substrate with such a decal. Conversely, the self-adhesive marking labels known have the advantage in general of better strength and good resistance to ultraviolet. However, they are not compatible with the subsequent application of a protective paint, for example a polyurethane paint. In addition, they are not very flexible and not compatible with an application on non-planar surfaces. The invention therefore aims to overcome all the drawbacks of the state of the art by providing a dry cold transfer marking which simultaneously has improved mechanical strength, is compatible with an application on any type of surface, including more or less tormented forms (such as the surfaces of vehicle bodies or aircraft cabins), either resistant to UV light over time (not likely to yellow, even partially), and is perfectly compatible with the polyurethane paints of protection that can be used to cover, after application to a substrate, both the transfer and the substrate. The invention also aims to provide such a transfer which can be applied to a substrate having a paint not perfectly dry, without hindering the subsequent drying of said paint. The invention also aims to provide such a transfer by which the component transferred to a substrate has a free external surface whose surface state may vary, that is to say be perfectly smooth and shiny, or otherwise matte The invention also aims at providing such a transfer which can be manufactured according to various techniques, including screen printing, deposition of layers by spraying and / or projection, for example by spraying, printing by digital printer ( For this purpose, the invention relates to a cold dry transfer comprising a support sheet, at least one layer of transparent polyurethane, at least one grounding pattern. printed label, and a layer of pressure-sensitive transfer adhesive, the carrier sheet, each layer of polyurethane and the transfer adhesive layer being adapted for the polyurethane layer to separate. completing the carrier sheet when the transfer is applied to a surface of a substrate via the transfer adhesive layer, characterized in combination that: - the polyurethane layer (s) form (a) a continuous integral polyurethane film extending to cover each printed marking pattern by defining the format of a single, transferred, integrally transferred component when using the transfer, the polyurethane film has a thickness greater than 30 m,

4 - the layer of transfer adhesive has a thickness greater than 40 m. Advantageously, a transfer according to the invention is also characterized in that it comprises at least two distinct printed marking patterns separated by at least a portion of the polyurethane film not covered by a printed marking pattern, and in that said polyurethane film is a continuous film extending to cover the different printed marking patterns and each portion of the backing sheet which is not facing a printed marking pattern, said distinct printed marking patterns being transferred as a single transferred component in a single piece when using the transfer. Furthermore, advantageously and according to the invention, said polyurethane film comprises at least one printed layer of a transparent polyurethane paint composition. It should be noted in this respect that a polyurethane paint must be distinguished from a composition of a varnish or ink for screen printing. In particular, a paint contains numerous additives adapted to its application as a surface coating, making it particularly resistant to mechanical and / or chemical attack and / or to ultraviolet and / or weathering.

The polyurethane film of a transfer according to the invention may comprise several successive layers made in any suitable manner. Nevertheless, preferably, and advantageously according to the invention, said polyurethane film is formed of a single continuous layer of a transparent polyurethane paint composition printed in screen printing.

In addition, advantageously and in a first embodiment according to the invention, the support sheet is formed of a film capable of serving as a screen printing medium on which said polyurethane film is directly applied. Advantageously and according to the invention, the support sheet is formed of a film selected from the group consisting of polyester films, polypropylene films, films of fluorocarbon materials (for example PVDF). Advantageously and according to the invention, the film has a thickness of between 75 m and 200 r-in particular of the order of 100 m-. In a second embodiment according to the invention, the carrier sheet is provided with an intermediate adhesive layer, said polyurethane film being applied to said intermediate adhesive layer, the carrier sheet via said intermediate adhesive layer and said transfer adhesive layer being adapted to allow the release of the carrier sheet and said polyurethane film when using the transfer after application to a surface of a substrate. In particular, the adhesive strength of the transfer adhesive layer on the substrate is greater than the adhesive strength of the intermediate adhesive layer. In this second embodiment, advantageously and according to the invention, the support sheet is formed of a material selected from the group consisting of papers, nonwovens, PVC, polypropylenes. Furthermore, advantageously, preferably and according to the invention, said polyurethane film has a thickness of less than 50 m.

In addition, advantageously and according to the invention, said layer of transfer adhesive is continuous and of a format corresponding to that of said polyurethane film. Advantageously and according to the invention, said transfer adhesive layer has a thickness of less than 200 m. Advantageously and preferably, a transfer according to the invention is adapted so that the transferred component has a total thickness greater than 90 m, but less than 300 m. The object of the invention is also to propose a method of marking which is simple and makes it possible to carry out a mechanically and ultraviolet resistant marking, and may be covered with a protective polyurethane paint without any particular precautions. The invention therefore extends to a method of marking a substrate surface by means of a transfer according to the invention.

Thus, the invention also relates to a method of marking a surface of a substrate in which a transfer is applied dry and cold on the surface so as to transfer a transferred component, and then covers this transferred component of a polyurethane paint coating, characterized in that one chooses and uses a cold dry transfer according to the invention.

Advantageously and according to the invention, one chooses and uses a transfer whose polyurethane film is formed of a polyurethane paint composition exactly the same nature as the polyurethane paint of the polyurethane paint layer covering the transferred component, it is that is to say, made of the same polyurethane base with the same additives (even if the hue or the color may be different.) A transfer according to the invention is therefore a hybrid device between a thicker, rigid, heavy and delicate self adhesive label. to set up and not compatible with many applications, for example for the marking of vehicles or aircraft, and a simple decal fragile, not very resistant to ultraviolet, and not compatible with most modern polyurethane protective paints. in a transfer according to the invention, the thick polyurethane film defines, in the manner of a front face of a self adhesive label, the format of the entire transfer and therefore different marking patterns simultaneously transferred. It offers high mechanical strength and perfect protection against ultraviolet light. Nevertheless, a transfer according to the invention is similar to a decal by its method of use and its flexibility. It is, however, much stronger and compatible with all polyurethane paints that can be used as a subsequent protective coating. The transfer adhesive can be adapted and be the subject of numerous variants (thickness, adhesive power, etc.). The invention also relates to a transfer and a method of marking characterized in combination by all or some of the characteristics mentioned above or below. Other objects, features and advantages of the invention will become apparent on reading the examples and the following non-limiting description and referring to the appended figures in which: FIGS. 1a-1d are diagrammatic sectional views illustrating 10 different successive steps of manufacturing a transfer according to a first embodiment of the invention, - Figures 2a and 2b are schematic sectional views illustrating two steps of using the transfer of Figure 1d in a process 3a and 3b are diagrammatic sectional views illustrating two steps of manufacturing a transfer according to a second embodiment of the invention from the transfer of FIG. Figure 4 is a schematic sectional view illustrating the use of the transfer of Figure 3b in a marking method according to the invention. In the figures, the scales are not respected, for illustrative purposes; in particular, the thicknesses are exaggeratedly enlarged. A transfer according to a first embodiment of the invention can be carried out as shown in Figs. 1a-1d. On a printing backing sheet 10, a continuous polyurethane film 11 is printed in a single piece free from reserve or recess. This polyurethane film 11 may be formed of a printed layer or of several layers successively printed on each other. The film 11 of polyurethane is transparent, that is to say

8 that it allows the passage of light in the visible range, and therefore, in particular, the visualization of marking patterns 12 through its thickness. It should be noted, however, that the film 11 of polyurethane may be totally transparent and clear, or on the contrary, more or less tinted or colored, depending on the applications. In the example shown in the figures, the polyurethane film 11 is printed in the same format as the printing medium sheet. Nevertheless, this printing medium sheet 10 also serving as a detachable transfer medium as explained hereinafter, nothing prevents the polyurethane film 11 from being of a smaller size than the backing sheet 10. impression. In any event, this polyurethane film 11 defines the format of a transferred component when using the transfer according to the invention. In a transfer according to the invention, this transferred component is unique and integral. In other words, when using the transfer according to the invention, a single component 20 in one piece carrying all the marking patterns 12 is transferred. The printing medium sheet 10 is, for example, formed from a polyester, polypropylene or other film, the thickness of which is between 75 m and 100 μm, in particular of the order of 100 μm. its two main faces by a coating such as an acrylic coating, adapted to allow at first the production of prints, then, during the transfer, the subsequent separation of the film 11 of polyurethane. In order to print the polyurethane film 11, a clear polyurethane paint composition is used, and not a polyurethane lacquer composition as used in screen printed polyurethane inks. In particular, such a polyurethane paint composition is much less viscous than a polyurethane varnish or a polyurethane varnish base. Such a polyurethane paint composition mainly contains polyurethane compounds having a molecular weight

9 relatively low, especially lower than that of the polyurethane compounds of a varnish or an ink. In addition, a polyurethane paint composition, unlike a polyurethane ink or a polyurethane varnish, contains many additives adapted to its application as a surface coating, in particular to make it resistant to mechanical and / or chemical attack and / or ultraviolet and / or weathering. For example, as the polyurethane paint composition that can be used to form the polyurethane film 11, the following polyurethane paints can be used: AVIOX UVR sold by ANAC, Akzo Nobel Aerospace Coatings, Waukegan, USA (2 parts) ; Thinner 99330 (1 part), hardener 90150 (1 part); reference CA8001BO900C marketed by PPG Industries, 15 Pittsburgh, USA (2 parts); diluent CA8000C2 (1 part), hardener reference HSCA8000B (1 part); - reference 411-14 marketed by MANKIEWICZ, Hamburg, Germany (2 parts); Thinner 901-72 (1 part), hardener reference 405-86 (1 part). This polyurethane paint composition is printed, for example by screen printing using a conventional screen printing machine, for example a cutter machine (hinged screen) or an integral lifting screen machine. In view of the low viscosity of such a polyurethane paint composition, which is normally unsuitable for screen printing, an initial phase of partial hardening of the composition is provided after mixing of its two constituent components (polyols and isocyanates), such that the composition achieves an appropriate viscosity prior to use for printing. Alternatively, the polyurethane paint composition may be printed by automatic or manual spraying. In any event, this printing is carried out so as to obtain a polyurethane film 11 whose thickness is greater than 30 m, preferably between 30 m and 50 m. Thus, after drying in an oven, for example at 60 ° C for 1 h, the blank shown in Figure la. On the film 11 of polyurethane is then printed (Figure lb) each marking pattern 12 to be applied using the transfer according to the invention. In the example shown, three letters 12a, 12b, 12c are printed. Thus, a marking pattern 12 may have recesses and is therefore not necessarily entirely full. Each letter 12a, 12b, 12c forms a distinct marking pattern and separated from the others by a portion 13 of the polyurethane film 11 not covered by such a marking pattern 12.

To print each marking pattern 12, a polyurethane ink is preferably used. Nevertheless, any other type of ink can be used as long as it is compatible with the polyurethane film 11, with its use in the transferred component, and with the transfer adhesive layer 15 described hereinafter. Each marking pattern 12 is printed so as to have a thickness for example of between 10 m and 20 m. A layer 15 of transfer adhesive covering the different marking patterns 12 and the polyurethane film 11 is then applied as shown in FIG. 1c. The composition and the thickness of this transfer adhesive layer 15 are chosen according to the application, and in particular the nature and characteristics (in particular surface state) of the surface 17 of the substrate 16 on which the transfer is made. must be applied. In any case, the layer 15 of transfer adhesive has a thickness greater than 40 m and preferably less than 200 m, for example of the order of 50 m for an application on a metal surface 17, or order of 100 m to 140 m for application to a surface 17 of carbon fiber composite material. The transfer adhesive layer 15 is formed of a cold-pressure (i.e., ambient temperature) pressure-sensitive adhesive composition. For example, an ultraviolet-resistant acrylic type adhesive composition can be advantageously used. The adhesive layer 15 is covered with a sheet of silicone paper 14 which can be easily separated before use of the transfer. The transfer adhesive layer 15 is a continuous layer of a format corresponding to that of the backing sheet. The transfer adhesive layer 15 thus covers all the marking patterns 12 which are interposed between the polyurethane film 11 and this transfer adhesive layer 15. Thus, the polyurethane film 11, the various marking patterns 12 and the transfer adhesive layer 15 constitute a single transferred component when using the transfer according to the invention. The adhesive layer may be selected to form a permanent (normally non-releasable), semi-permanent or removable (normally peelable) adhesive. Preferably, as shown in FIG. 1 d, a peripheral half-cut is then produced in the silicone paper 14, the adhesive layer 15 and the polyurethane film 11, and then a squeezing of the peripheral edge of these layers with respect to to the backing sheet 10 so as to form a peripheral overhang 23 facilitating subsequent peeling of the backing sheet 10. The transfer according to the first embodiment of the invention as represented in FIG. 1d can be used in a marking method such as a cold dry transfer, for example as described in FR 2776236. FIG. 2a thus illustrates the transfer in use in a marking process according to the invention, with the layer 15 of transfer adhesive

12 applied on the surface 17 of a substrate 16 which, in the example shown, is a metal substrate previously covered with a layer 18 of paint. Pressure is exerted on the support sheet so as to activate the adhesive of the transfer adhesive layer. As can be seen, the backing sheet 10 can then be easily peeled away from the polyurethane sheet 11 after activation by simply pressing the adhesive of the transfer adhesive layer 15. The transferred component is then secured to the surface 17 of the substrate 16. In the subsequent step shown in FIG. 2b, a coating 19 of transparent or translucent protective polyurethane paint (to allow the visualization of the marking patterns 12) is applied. in one or more layer (s) covering the transferred component 20, that is to say, covering the film of polyurethane 11 which forms, after transfer, at the end of the step of Figure 2a, the external face of the transferred component 20, the latter then being embedded in the coating 19 of protective polyurethane paint.

It should be noted that the polyurethane film 11 formed of a polyurethane paint composition is fully compatible with the protective polyurethane paint coating 19 covering the transferred component. As a result, the protective polyurethane paint coating 19 adheres perfectly to the polyurethane film 11 without damaging it in any way. It should also be noted that the transferred component has mechanical characteristics, and in particular a thickness, compatible with its use on an outer surface of a vehicle or aircraft, that is to say it resists the attacks of the atmospheric environment. resulting from a high speed displacement is of a long life and does not deteriorate under the effect of ultraviolet. In particular, the film 11 of polyurethane paint of relatively large thickness is particularly resistant. However, it is not completely hermetic, and thus allows the end of the drying of the paint layer 18

13 on which the transferred component is applied. The total thickness of the transferred component is, after transfer and crushing of the transfer adhesive layer, greater than 50 m, typically of the order of 75 m to 200 m. In any case, it is generally less than 300 m.

The invention thus achieves for the first time to achieve a particularly advantageous compromise between a simple self-adhesive label, too thick and not compatible with a protective polyurethane paint, and a simple decal, too fragile and not perfectly compatible with a protective polyurethane paint .

Given its relative rigidity, the sheet 10 of polyester printing medium is not always adapted to allow the use of a transfer according to the invention on a surface 17 having tormented forms. In this case, it is advantageous to replace this backing sheet with a suitable flexible backing sheet 21. To do this, from the transfer according to the first embodiment shown in FIG. 1d, the backing sheet 10 is separated from the polyurethane film 11, either manually or with the aid of a specially designed automatic machine. for this purpose and known in itself, as shown in Figure 3a. This separation is facilitated by the peripheral overhang 23. Alternatively not shown, a reserve or a cutout may be provided in a corner of the polyurethane film 11 or the printing medium sheet. Taking into account in particular the thickness of the film 11 of polyurethane, this separation is easy and can be carried out for example by the fingernail. The polyurethane film 11 is then applied to a sheet 21 of flexible support, for example paper, non-woven, PVC, polypropylene or other, via a layer 22 of intermediate adhesive previously applied to this sheet 21 supple support. As such, it can simply be used as flexible support sheet 21, an adhesive transfer paper traditionally used for the cold transfer cold transfer.

As seen in FIG. 4, a transfer according to this second embodiment of the invention is used in a marking method according to the invention similarly to the first embodiment by applying the transfer adhesive layer 15. on the surface 17 of the substrate, and then detaching the flexible support sheet 21 and its layer 22 of intermediate adhesive. To enable this detachment, the adhesive power of the intermediate adhesive layer 22 must be less than the adhesive power provided by the transfer adhesive layer 15 on the substrate surface 17. Since the layer 15 of transfer adhesive is chosen to have a very high adhesive power, this condition is easily obtained by choosing, for the intermediate adhesive layer 22, a lower quality adhesion adhesive composition. . A protective polyurethane paint coating 19 may then be applied overlying the transferred component as in the first embodiment.

It goes without saying that the invention can be the subject of many variants with respect to the preferred embodiments shown in the figures and described above. In particular, the polyurethane film 11 can be made in several layers; the polyurethane paint composition used to form the polyurethane film 11 can be adapted to each situation, in particular be exactly the same composition as the polyurethane paint used to form the protective coating 19; the marking patterns 12 may be arbitrary, and the transfer adhesive layer 15 may be subject to numerous variations depending on the intended application.

Claims (1)

CLAIMS1 / - Dry dry transfer comprising a support sheet (10, 21), at least one transparent polyurethane layer, at least one printed marking pattern (12), and a layer (15) of sensitive transfer adhesive pressure, the carrier sheet (10, 21), each layer (15) of polyurethane and the transfer adhesive layer being adapted for the polyurethane layer to separate from the carrier sheet (10, 21) when the transfer is applied to a surface (17) of a substrate via the layer (15) of transfer adhesive, characterized in combination that: - the layer (s) of polyurethane form ( nt) an integral continuous polyurethane film (11) extending to cover each printed marking pattern (12) by defining the format of a single, integrally transferred component (20) when of the use of the transfer, the film (11) of polyurethane has a thickness greater than less than 30 m, - the layer (15) of transfer adhesive has a thickness greater than 40 m. 2 / - Transfer according to claim 1, characterized in that it comprises at least two distinct printed marking patterns (12) separated by at least a portion (13) of the film (11) of polyurethane not covered by a pattern ( 12), and that said polyurethane film (11) is a continuous film extending to cover the various printed marking patterns (12) and each portion of the support sheet (10, 21). which is not facing a printed marking pattern (12), said distinct printed marking patterns (12) being transferred as a single, integrally transferred component (20) when use of the transfer. 3 / - Transfer according to one of claims 1 or 2, characterized in that said film (11) of polyurethane comprises at leasta printed layer of a transparent polyurethane paint composition. 4 / - Transfer according to one of claims 1 to 3, characterized in that said film (11) of polyurethane is formed of a single continuous layer of a transparent polyurethane paint composition printed in screen printing. 5 / - Transfer according to one of claims 1 to 4, characterized in that said film (11) of polyurethane has a thickness of less than 50 m. 6 / - Transfer according to one of claims 1 to 5, characterized in that said layer (15) of transfer adhesive is continuous and of a format corresponding to that of said film (11) of polyurethane. 7 / - Transfer according to one of claims 1 to 6, characterized in that said layer (15) of transfer adhesive has a thickness of less than 200 m. 8 / - Transfer according to one of claims 1 to 7, characterized in that it is adapted so that the component (20) transferred has a total thickness greater than 90 m and less than 300 m. 9 / - Transfer according to one of claims 1 to 8, characterized in that the sheet (10) support is formed of a film adapted to act as a screen printing medium on which said film (11) of polyurethane is directly applied. 10 / - Transfer according to claim 9, characterized in that the sheet (10) of support is formed of a film having a thickness of between 75 m and 200 pm - in particular of the order of 100 m-. 11 / - Transfer according to one of claims 1 to 8, characterized in that the sheet (21) support is provided with a layer (22) of intermediate adhesive, said film (11) of polyurethane being applied to the carrier sheet (21) through said intermediate adhesive layer (22), said intermediate adhesive layer (22) and said transfer adhesive layer (15) being adapted to allow the release of the sheet (21) support and said polyurethane film (11) when using transfer after application to a surface (17) of a substrate. 12 / - Transfer according to claim 11, characterized in that the sheet (21) of support is formed of a material selected from the group consisting of paper, nonwovens, PVC, polypropylenes. 13 / - A method of marking a surface (17) of a substrate (16) in which a transfer is applied dry and cold on the surface (17) so as to transfer a component (20) transferred, and then this component (20) transferred is covered with a coating (19) of polyurethane paint, characterized in that a cold dry transfer according to one of claims 1 to 12 is used. 14 / - Method according to claim 13 , characterized in that a transfer is used in which the polyurethane film (11) is formed of a polyurethane paint composition of exactly the same nature as the polyurethane paint of the polyurethane paint coating (19) covering the transferred component (20). .