EP1584484B1 - Apparatus and process for printing on thermoplastic floor tiles - Google Patents

Abstract

A method for printing thermoplastic floor tiles involves printing tiles in a horizontal position with UV-drying ink, drying the ink (after application in the case of direct printing or before in the case of indirect printing), then applying a protective coating and drying the coating. A method for printing and protecting the print on thermoplastic floor tiles, involves (a) positioning at least one prefabricated tile (1) so that at least one of the sides (5, 5') to be printed is horizontal, (b) applying at least one layer (6) of UV-drying ink to at least part of that surface (5, 5'), drying being effected after application to the surface for a direct print or before application for an indirect print, (c) applying protective coating(s) (9) to the top layer of ink and (d) drying the protective coating (9). An independent claim is also included for apparatus for printing thermoplastic floor tiles, comprising a means of supporting tiles in a horizontal position (especially a table, tray or conveyor belt), a system for depositing layer(s) of UV-drying ink (e.g. a direct printing station for silk-screen printing or micro-drop deposition, or an indirect printing station for thermal transfer processes), a system for applying a protective coating (especially a varnishing station) and a UV-drying unit, preferably comprising UV lamps emitting in the 220-440 range.

Description

The invention relates to a method for printing and protecting the printing of thermoplastic material slabs adapted to form at least a portion of a reported floor.

The invention also relates to an installation for printing and the protection of this printing, by such a method, of slabs of thermoplastic material.

Such slabs are used to form a ground floor placed on an existing floor or surface, for example a concrete screed, a floor, a tile. This soil is intended to replace this surface. We know, especially in industries, shops and public or collective premises, such reported soil. The slabs usually used have various colors and, optionally, a face having a non-smooth appearance, for example in "grains of rice", grained or glittery. These slabs can also have their upper face evoking a type of coating, for example wood, marble or other decor. Such characteristics are achieved during the manufacture of the slabs and are made from the material constituting the slab. We know, by GB-A-2,041,244 a printing process in which, by flexography, one side of a slab based on vinyl polymer is printed. After drying under ultraviolet radiation, a passage of the slab between two rollers, one of which is provided with a scraper, carries out the shaping of a granite face, the latter being then printed and coated with a protective varnish. This is a two-step impression.

We also know, by EP-A-0 143 135 , a method in which a resin sub-layer is applied to a plastic support, and before this dry undercoat, inks of different colors. It is not possible to change the appearance of such slabs. If one wants to change the appearance of the upper face of the slabs, for example for informational purposes by putting security pictograms or for a decorative purpose or advertising, it is generally carried out by the application of stickers or cuts practiced in the slab to insert elements of shapes and / or various colors.

In all cases, these solutions are not easy to implement and are not satisfactory. Indeed, in the case of stickers, repeated passages of people and / or gear on the slabs quickly lead to wear and tear of the latter. The realization of cuts in the slabs and the insertion of other elements in the latter, allow to achieve only certain markings. Moreover, the induced costs do not allow unit production or in small series.

It is to these drawbacks that the invention more particularly intends to remedy by proposing a method of printing and protecting the printing of slabs of thermoplastic material, flexible to use, adaptable to all types of marking, scalable. In addition, the slabs obtained by this method are resistant to wear and are of a low production cost for custom production, customizable, especially in small series.

1. a) positionner, postérieurement à sa fabrication, au moins une dalle équipée sur au moins une partie de sa périphérie d'organes de liaison permettant de relier ensemble des dalles, de manière à ce qu'au moins une des faces à imprimer soit sensiblement dans un plan horizontal,
2. b) déposer par projection, sur au moins une partie de ladite face, au moins une couche, en au moins une passe, d'une encre à séchage par rayonnement ultraviolet, le séchage étant effectué postérieurement au dépôt de l'encre sur la face pour une impression directe ou antérieurement au dépôt de l'encre sur la face pour une impression indirecte,
   caractérisé en ce qu'il comprend des étapes consistant à :
3. c) appliquer sur la couche supérieure d'encre au moins une couche d'un revêtement protecteur en poudre,
4. d) effectuer la liquéfaction ou « gélification » de la couche de revêtement protecteur à une température comprise entre 110°C et 150°C, sous rayonnement infrarouge de manière à former une couche uniforme de revêtement protecteur et
5. e) effectuer le séchage de la couche de revêtement protecteur.

To this end, the subject of the invention is a process for printing and protecting the printing of thermoplastic material slabs adapted to form at least part of a reported floor, comprising the steps of:

1. a) positioning, after its manufacture, at least one slab equipped on at least a part of its periphery of connecting members for connecting together slabs, so that at least one of the faces to be printed is substantially in a horizontal plane,
2. b) depositing, by projection, on at least a portion of said face, at least one layer, in at least one pass, of an ultraviolet-radiation drying ink, the drying being carried out after the depositing of the ink on the face; for direct printing or prior to depositing the ink on the face for indirect printing,
   characterized by comprising steps of:
3. c) applying on the upper layer of ink at least one layer of a protective powder coating,
4. d) liquefying or "gelling" the protective coating layer at a temperature between 110 ° C and 150 ° C under infrared radiation so as to form a uniform layer of protective coating and
5. e) drying the protective coating layer.

Thanks to the method of the invention, an impression is obtained on all shapes and sizes of slabs. This impression has a high wear resistance and can be performed both unit and mass production for advantageous production costs, while being easily customizable.

• Lors de l'étape e), le séchage de la couche de revêtement protecteur est effectué par rayonnement ultraviolet.
• La couche de revêtement protecteur est un vernis, notamment un vernis en poudre à base de résines mixtes époxy-polyester. En variante, la couche de revêtement protecteur est un vernis en poudre à base polyuréthane.
• Lors de l'étape a), on juxtapose plusieurs dalles, leurs faces à imprimer étant situées dans un même plan, de manière à ce que la somme des surfaces unitaires des dalles soit sensiblement égale à la surface à imprimer. Lors de leur juxtaposition, les dalles sont maintenues mutuellement en position par des organes de liaison, notamment des organes de type tenon/mortaise.
• Après l'étape b) et avant l'étape c) on sépare, lors d'une étape f), les dalles les unes des autres.
• Avant l'étape b) ou l'étape a), on dégraisse, lors d'une étape g), les dalles préalablement à l'application de la première couche d'encre.
• Avant l'étape c) ou après l'étape e), on effectue, lors d'une étape h), un refroidissement des dalles, notamment en les plaçant dans un courant d'air.
• Après l'étape e) ou après l'étape g), on repositionne, lors d'une nouvelle étape a), au moins une dalle déjà imprimée pour effectuer une autre impression sur la même dalle.
• Avant l'étape b), on applique, lors d'une étape i), une sous couche sur la face à imprimer. Avantageusement, cette sous-couche est d'une teinte neutre vis-à-vis de chaque couleur imprimée, notamment la sous-couche est opacifiante, par exemple blanche.
• On utilise des dalles en polymère thermoplastique, notamment en PVC, d'une dureté Shore A de 65 à 100 et, avantageusement, de 85 à 95.

According to advantageous but non-mandatory aspects of the invention, such a method can incorporate one or more of the following features:

• In step e), the drying of the protective coating layer is carried out by ultraviolet radiation.
• The protective coating layer is a varnish, especially a powder lacquer based on mixed epoxy-polyester resins. Alternatively, the protective coating layer is a polyurethane-based powder coating.
• During step a), several slabs are juxtaposed, their printing faces being located in the same plane, so that the sum of the unit surfaces of the slabs is substantially equal to the surface to be printed. During their juxtaposition, the slabs are held mutually in position by connecting members, including mortise / tenon type members.
• After step b) and before step c), during a step f), the slabs are separated from each other.
• Before step b) or step a), in step g), the slabs are degreased prior to the application of the first ink layer.
• Before step c) or after step e), during a step h), the slabs are cooled, in particular by placing them in a stream of air.
• After step e) or after step g), at a new step a), at least one slab already printed is repositioned to make another printing on the same slab.
• Before step b), during a step i), an undercoat is applied to the face to be printed. Advantageously, this underlayer is of a neutral hue with respect to each printed color, in particular the underlayer is opacifying, for example white.
• Thermoplastic polymer slabs, in particular PVC, with a Shore A hardness of from 65 to 100 and, advantageously, from 85 to 95, are used.

• des moyens de support d'au moins une dalle de manière à ce qu'au moins une des faces à imprimer soit dans un plan sensiblement horizontal, notamment une table, un plateau ou un tapis convoyeur,
• des moyens de dépôt d'au moins une couche d'encre à séchage par rayonnement ultraviolet en au moins une passe, notamment un poste d'impression, par exemple d'impression directe par sérigraphie ou dépôt de microgouttes ou un poste d'impression indirecte par transfert thermique,
• des moyens de dépôt d'un revêtement protecteur en poudre, notamment un poste de dépôt d'un vernis associés à un poste de liquéfaction ou de « gélification » du revêtement protecteur par rayonnement infrarouge, le poste comprenant des lampes d'une longueur d'ondes comprise entre 1,1 et 2,6 micromètres,
• des moyens de séchage par rayonnement ultraviolet, notamment des lampes de longueur d'ondes émises comprise entre 220 et 440 nanomètres.

The invention also relates to an installation for implementing a method for printing slabs of thermoplastic material and, in particular, an installation comprising:

• means for supporting at least one slab so that at least one of the faces to be printed is in a substantially horizontal plane, in particular a table, a tray or a conveyor belt,
• means for depositing at least one ultraviolet-radiation-drying ink layer in at least one pass, in particular a printing station, for example direct printing by screen printing or microdrop deposit or an indirect printing station by heat transfer,
• means for depositing a protective powder coating, in particular a lacquer deposition station associated with a liquefaction or "gelling" station of the protective coating by infrared radiation, the station comprising lamps with a length of waves between 1.1 and 2.6 micrometers,
• means for drying by ultraviolet radiation, in particular lamps with wavelengths of between 220 and 440 nanometers.

Advantageously, such an installation also comprises means for drying at least one layer of ink by ultraviolet radiation when the ink layer is deposited by direct printing. Such an installation may comprise at least one cooling means, in particular a blower disposed at the outlet of at least one of the drying means.

• la figure 1 est une vue générale d'une dalle, telle qu'utilisée dans le procédé d'impression conforme à l'invention, avant impression,
• la figure 2 est une vue générale d'une partie d'un sol rapporté, formé de plusieurs dalles juxtaposées et imprimées selon le procédé conforme à l'invention et
• la figure 3 est un diagramme d'une installation permettant la mise en oeuvre d'un procédé d'impression conforme à l'invention.

The invention will be better understood and other advantages thereof will appear more clearly in the light of the following description of an embodiment of a printing method according to the invention, given solely for the purpose of example and made with reference to the accompanying drawings in which:

• the figure 1 is a general view of a slab, as used in the printing process according to the invention, before printing,
• the figure 2 is a general view of a portion of a reported floor, formed of several slabs juxtaposed and printed according to the method according to the invention and
• the figure 3 is a diagram of an installation allowing the implementation of a printing method according to the invention.

Slab 1, shown in figure 1 , is a thermoplastic polymer slab and, in particular, a PVC slab. This slab is semi rigid. In this case, its Shore A hardness is generally between 85 and 95. Slabs having a Shore A hardness between 65 and 100 can, in practice, be used. Typically, slabs, of the slab type 1, are adapted to be placed on an existing floor or surface, as long as this floor or surface is stable, relatively flat and rigid. It may be, for example, a concrete screed, a floor, a tile or any other known floor. The slabs 1 can be fixed to this floor, for example by gluing, screwing or using fasteners known per se. The slabs 1 can also be placed on the ground without being secured to the latter.

These slabs 1 may be equipped, on at least a part of their periphery, connecting members 2 to connect together and maintain juxtaposed. Thus, as represented in figure 2 several slabs 1 juxtaposed form part of a reported soil. The connecting members 2 comprise several lugs 3, generally T-shaped and evenly spaced on the periphery of the slabs 1. These connecting members 2 are such that a lug 3 of a slab 1 is adapted to be housed in the space 4 located between two lugs 3 of another slab 1 adjacent. When it is desired to print one or more faces 5 of these slabs 1, including, optionally, the connecting members 2, one positions, as shown in the right part of the figure 3 , the face 5 to be printed in a substantially horizontal plane P, by placing, for example, the slab 1 on a table or conveyor belt. Depending on the area of the surface to be printed, one or more slabs 1 are used. In this case, the slabs 1 are assembled and held in position by virtue of their respective connecting members 2. During assembly, it is ensured that all the faces 5 to be printed are in the same horizontal plane P, these faces 5 must all be accessible simultaneously for the subsequent steps of the method.

The slabs 1 are thus printed, unitarily or assembled flat, that is to say in a position similar to that they once in place on the original floor.

If necessary, the surfaces to be printed are degreased, the purpose of this degreasing is to eliminate solid and / or liquid soils, in particular the fatty residues resulting from the manufacture of the slabs 1. This degreasing is carried out by known techniques. in itself like, for example, the chemical degreasing using isopropyl alcohol, flaming, electrical discharge by blown arc systems, plasma or corona discharge.

The method makes it possible to print the faces 5 of the slab 1 whatever the appearance of these faces. Thus, it is possible to print smooth or non-smooth faces, especially granular faces, in "rice grains", sequined or grained.

After positioning the slab or slabs 1 on a working support, a first step of printing is performed by depositing on this or these faces 5 a layer 6 of one or more inks. Advantageously, each ink is drying, that is to say polymerization or crosslinking, by ultraviolet rays. These inks are in liquid or powder form.

This ink or inks is deposited by techniques relating, for example, to direct printing, in particular to digital printing. In this case, ink microdroplets are projected on the faces 5 to be printed. Thus, one or more inks are deposited on the faces 5, regardless of the surface state thereof, smooth or not smooth, which makes it possible to differentiate from the state of the art disclosed by GB-A-2,041,244 . Depending on whether monochrome or quadrichrome printing is desired, and depending on the number of available printheads, the number of passes required of the ink deposition system is performed above the print side. This technique is known as "drop on demand".

One can also use, always in direct printing, the technique of screens of silk or serigraphy. In this case, the ink is applied, hue by hue, using screens or stencils, on the areas to be printed, with the same hue, faces 5.

The actual fixing of the ink layer on the faces 5, whatever the technique employed, is obtained by drying the ink under ultraviolet rays. This passage under UV rays allows drying of the ink layer 6 at a sufficiently high temperature and for a time long enough to ensure the drying of the ink but short enough not to reach the melting point of the constituent material of the ink. slabs 1. This drying technique allows the use, for the slabs 1, of semi-rigid thermoplastic material with a low melting temperature, close to 180 ° C. Ultraviolet drying is carried out at temperatures between about 90 ° C and 100 ° C, the slabs 1 being, at the end of drying, at temperatures of between 77 ° C and 82 ° C.

Alternatively, an indirect printing technique may be used, for example, by heat transfer. In this case, the ink is "carried" by a so-called transfer paper then sublimated, namely heated between 120 ° and 150 ° C for 15 to 50 seconds under a pressure of between 2 and 5 bar. During this sublimation, the ink passes directly from the solid state to the gaseous state and enters the constituent material of the slab 1 at the faces 5 to be printed. The ink is dried by ultraviolet radiation when it is deposited on the transfer paper before being transferred to the print side. This drying solidifies the ink to then perform sublimation.

This step can be followed, if necessary, a cooling slabs 1 for example by passing them in a stream of air at a temperature below or close to room temperature. This cooling reduces the temperature of the slabs 1 to a value approximating the initial temperature of the slabs 1, during step a) of the process, which makes it possible to preserve the dimensional stability of the slabs. Advantageously, the slabs pass under a blower 8 of refrigerated air or not.

The next step is to apply at least one layer of protective coating on the ink layer 6 to preserve the impression of the slab 1.

This application of protective coating can be done on the slabs 1 assembled or on slabs 1 separated from each other. This variant allows to perform in two different places, the printing and application of the protective coating while occupying a minimum of space. The coating or protective varnish can be applied directly after printing for example, without cooling slabs or after cooling slabs. The time interval ΔT between the end of the printing and the application of the protective coating is variable.

In all cases, the nature of slabs 1, inks and protective coating are adapted to be chemically compatible.

It is also possible to rearrange the slabs 1 differently so as, for example, to obtain, when the protective coating is applied, a working surface with an area greater or smaller than the printing surface. For example, it is possible to group together several slabs 1 printed during different impressions to obtain a larger surface area of application of the protective coating and thus optimize the process. Just make sure that the printed faces 5 slabs 1 associated or neighboring are all located in the same plane. It is thus possible to have supports bearing several adjacent rows of slabs 1.

During the implementation of this coating step, a protective coating layer is applied to the printed face, advantageously a powdered, thermosetting varnish, for example a varnish based on mixed epoxy and polyester resins or polyurethane resins. The application of this layer of varnish 9 is, for example, using an electrostatic gun either triboelectric type or corona type. A protective film of the varnish 9 with a thickness of between 20 and 70 microns and, advantageously, between 35 and 55 microns is thus deposited.

This powder varnish 9 undergoes, at first, a preheating to liquefy or gel. This preheating is done by techniques known per se and, in particular, under infrared radiation. The infrared lamps used have a wavelength of between 1.1 and 2.6 micrometers. In this case, the lamps used are carbon-emitting, with a power of about 40 watts per centimeter. This preheating is carried out at a temperature generally between 110 ° and 150 ° C and preferably between 135 ° C and 150 ° C for a time between 30 and 120 seconds.

The liquefaction can also be carried out by passing the slabs in an oven or an oven, by adjusting the temperature and the time of passage in the oven or oven.

Preheating makes it possible to liquefy and evenly distribute the varnish 9 on the face 5 to be printed. The actual drying is then carried out by passing the layer of varnish 9 thus liquefied under ultraviolet radiation for a few seconds at about 120 ° C. in order to crosslink the varnish 9. This crosslinking, or polymerization, of the varnish proceeds without affecting neither the ink nor the material constituting the slab 1. Advantageously, mercury or mercury / gallium lamps 7 are used, the wavelengths of which, in the ultraviolet, are between 220 and 440 nanometers. It is also possible, at the end of drying and before storing or handling the slabs 1, to cool them by passing through an air stream 8 refrigerated or not.

Such a printing process can be repeated several times. On a slab 1 printed and varnished, it is possible to make another printing. In this case, if necessary, a slight degreasing of the slab is carried out. It can also be printed directly on the varnish layer 9 without degreasing.

This method is applicable to print indifferently an upper face 5 'or a 5' lower face of the slab. When it is desired to print the lower face 5 'of the slab 1, that is to say the face of the slab in contact with the existing floor, the same method is used, but here the ink forms, in negative, the pattern to print. The protective layer of the printing may be of a thickness different from that previously used, this protective layer not having to be in contact with the outside.

The varnish 9 serves only to preserve the impression of the contact with the ground on which the slab is placed, the protection against wear due to repeated passages on the slab does not need to be. The protection of the visible part of the printing is done by the slab 1 itself. Such a method is particularly suitable for use in the framework of slabs 1 made of transparent or translucent thermoplastic material.

It is also possible, in the case of an impression or prior to the first ink deposition step, to apply to the face 5, 5 'which it is desired to print, a sub-layer based on a monochrome ink. This underlay must be of a neutral hue not altering the colors of the print. Advantageously, an opacifying sub-layer, for example white, is used which makes it possible to have a neutral background, or primer, for printing. This sub-layer is particularly useful when the initial color of the slab is not in agreement with the colors of the print and may change the perception of the latter. This sub-layer, once applied, is for example crosslinked under ultraviolet radiation.

Of course, in the case of slabs 1 transparent or translucent, it does not apply tinted undercoat prior to the deposition of the ink, this sub-layer does not allow the vision of printing. On the other hand, it is possible to apply, on the face 5 ', a transparent undercoat, in particular a layer of varnish.

As a variant, it is possible to limit the printing of the slabs 1 to a part of the surface of the slabs 1, for example to the exclusion of the connecting members 2.

Claims (16)

1. Process for printing and protecting the print on tiles made of thermoplastic material which are suitable for forming at least part of a filled floor, comprising steps in which:

   a) at least one tile (1) equipped on at least part of its periphery with connecting elements (2) allowing tiles (1) to be joined together is positioned, following its manufacture, in such a manner that at least one of the faces (5, 5') of the tiles that are to be printed is substantially in a horizontal plane,

   b) there is deposited by spraying, on at least part of said face (5, 5'), at least one layer (6), in at least one pass, of an ink that dries by ultraviolet radiation, said drying being carried out after the ink has been deposited on said face (5, 5') for direct printing or before the ink is deposited on said face (5, 5') for indirect printing,
   characterised in that it comprises steps in which:

   c) at least one layer (9) of a protective powder coating is applied to the upper layer (6) of ink,

   d) liquefaction or "gelling" (10) of said layer (9) is carried out at a temperature of from 110°C to 150°C, under infrared radiation, in order to form a uniform protective coating layer, and

   e) drying of said protective coating layer (9) is carried out.
2. Process according to claim 1, characterised in that, in step e), drying of the protective coating layer (9) is carried out by ultraviolet radiation.
3. Process according to claim 1 or 2, characterised in that said protective coating layer is a varnish (9), especially a powder varnish based on mixed epoxy-polyester resins.
4. Process according to claim 1 or 2, characterised in that said coating layer (9) is a powder varnish based on polyurethane.
5. Process according to any one of the preceding claims, characterised in that, in step a), a plurality of tiles (1) are placed side by side, their faces (5, 5') that are to be printed being located in the same plane (P), in such a manner that the sum of the unit areas of said tiles (1) is substantially equal to the area to be printed.
6. Process according to claim 5, characterised in that, when the tiles (1) are placed side by side, they are held mutually in position by connecting elements (2), especially elements (3) of the tenon/mortise type.
7. Process according to either claim 5 or claim 6, characterised in that, after step b) and before step c), said tiles (1) are separated from one another in a step f).
8. Process according to any one of the preceding claims, characterised in that, before step b) or step a), the tiles (1) are degreased, in a step g), before the first layer (6) of ink is applied.
9. Process according to any one of the preceding claims, characterised in that, before step c) or after step e), the tiles are cooled in a step h), especially by being placed in a stream of air (8).
10. Process according to claim 9, characterised in that, after step e) or after step g), at least one tile (1) that has already been printed is repositioned, in a new step a), in order to carry out a further printing operation on the same tile.
11. Process according to any one of the preceding claims, characterised in that, before step b), an underlayer is applied, in a step i), to said face (5, 5') that is to be printed.
12. Process according to claim 11, characterised in that said underlayer is an ink that is neutral with respect to each colour printed, especially the underlayer is opacifying, for example white.
13. Process according to any one of the preceding claims, characterised in that tiles (1) made of thermoplastic polymer, especially of PVC, and having a Shore A hardness of from 65 to 100 and advantageously from 85 to 95 are used.
14. Installation for printing tiles made of thermoplastic material, comprising:

    - means for supporting at least one tile (1) in such a manner that at least one of the faces (5, 5') that are to be printed is in a substantially horizontal plane, especially a table, a plate or a conveyor belt,

    - means for depositing at least one layer (6) of ink that dries by ultraviolet radiation in at least one pass, especially a printing station, for example a station fcr direct printing by screen printing or deposition of microdrops or a station for indirect printing by heat transfer,

    characterised in that it comprises:

    - means for depositing a protective powder coating, especially a station for depositing a varnish (9), which means are associated with a station for liquefaction or "gelling" of said protective coating by infrared radiation, said station comprising lamps (10) having a wavelength of from 1.1 to 2.6 micrometres,

    - means for drying by ultraviolet radiation, especially lamps (7) having an emitted wavelength of from 220 to 440 nanometres.
15. Installation according to claim 14, characterised in that it also comprises means for drying at least one layer (6) of ink by ultraviolet radiation when said layer (6) is deposited by direct printing.
16. Installation according to either claim 14 or claim 15, characterised in that it comprises at least one cooling means, especially a blower (8) arranged at the outlet of at least one of the drying means (7).

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