EP1360076A1

EP1360076A1 - Film and hot-stamping method

Info

Publication number: EP1360076A1
Application number: EP02703671A
Authority: EP
Inventors: Alain Bethune
Original assignee: LOreal SA
Current assignee: LOreal SA
Priority date: 2001-02-07
Filing date: 2002-02-06
Publication date: 2003-11-12
Also published as: WO2002062592A1; AR034574A1; FR2820348B1; US20040131847A1; JP2004525790A; FR2820348A1

Abstract

The invention relates to a film (10) used to decorate a surface (100), particularly of glass or metal, by hot stamping. Said film comprises a first heat-sensitive adhesive layer (11) intended to be brought into contact with said surface, a second layer (12) made from a material that can form said decoration and a protective support (13) which is fixed to the second layer by means of a layer (14) made from a heat-sensitive material. The invention is characterised in that the film comprises at least one first compound (20) which can react chemically in a humid environment with at least a second compound of said surface (100) in such a way as to encourage the adhesion of the film during the application thereof on said surface.

Description

FILM AND HOT MARKING METHOD

The present invention relates to a film and a method for decorating by hot stamping a surface, in particular glass, crystal, ceramic, metal or metal alloys, etc.

Glass, crystal, metal or metal alloy surfaces are traditionally decorated by ink printing, enameling, chemical attack or painting. Such decoration methods have several drawbacks. Indeed, they cause evaporations of solvent, and of CO ₂ , in particular during the annealing of the inks. Furthermore, they do not make it possible to obtain certain types of decoration, such as for example metallic renderings of all colors which can be obtained by hot marking processes. However, it is difficult to use a hot stamping process on smooth inorganic surfaces such as glass, crystal or metal, since the adhesive compositions provided on the hot stamping films adhere little to such surfaces.

US Patent 6,136,382 describes a process for decorating a glassy article which improves the adhesion of a decoration, in particular obtained by hot stamping. The method consists in applying by spraying, on the glassy article, a composition based on silane, then in applying an ink which is dried by an appropriate radiation. A traditional hot stamping film is then applied to the areas on which ink has been deposited at a temperature which allows an adhesive layer of the hot marking film to adhere to the areas decorated with the ink. The film is not applied directly to the glass surface but an intermediate layer is required. Furthermore, in this type of process, the decoration must be applied relatively quickly after treating the glass because the glass is not stable over time, the silane-based composition will tend, over time, to lose its effectiveness. as for its function of adhesion promoter. Indeed, during the melting of the glass, there is a soda release because, the sodium-oxygen bond being very weak, there is release of sodium ions which make the medium alkaline. The alkaline OH ions ^" chemically attack silica and make the glass surface unstable.

Patent applications EP 0 668 170 and EP 0 825 218 also describe methods for decorating a glass or ceramic article in which, before applying a hot stamping film, a silane composition is sprayed onto the glass or ceramic item. Again, the decoration must be applied relatively quickly after treating the glass because the silane-based composition will tend, over time, to lose its effectiveness as regards its function as an adhesion promoter.

US Patent 3,907,974 describes heat transferable decals forming transferable labels on glass or ceramic surfaces. The labels are formed of several layers, in particular a layer of varnish, a layer of a printed design and an adhesive layer. In order to improve the stability of the label, its resistance to chemicals, its resistance to abrasion and rubbing, at least one of the layers contains polymerizable cross-linking agents which are capable of cross-linking the resins present in layers adjacent to form strong chemical cohesion bonds between layers as well as within a single layer. Before applying the label to a surface, for example glass, it is necessary to treat this surface with an agent promoting adhesion such as silane. Thus, there are the same drawbacks as those which have just been discussed previously related to the prior spraying of silane on the surface to be decorated.

It is therefore one of the objects of the invention to produce a film and a method for decorating by hot stamping making it possible to improve the adhesion of the film to a surface which is in particular not receptive to an adhesive composition which does not do not have the drawbacks of the prior art.

It is in particular an object of the invention to provide a hot stamping method which is independent of the manufacture of the surface to be decorated. and in particular which does not require a preliminary treatment of the surface nor of coating of intermediate layer.

According to the invention, these objects are achieved by producing a film for decoration by hot stamping a surface, in particular made of glass or metal, the film comprising a first layer of a heat-sensitive adhesive intended to be brought into contact with said surface, a second layer of a material, capable of forming said decoration, a protective support fixed to the second layer by means of a layer of heat-sensitive material, characterized in that the film comprises at least one first compound capable of reacting chemically in a humid environment with at least one second compound of said surface so as to promote the adhesion of the film when it is applied to said surface.

Thus, the compound promoting the adhesion of the film to the surface being in the hot stamping film, the structure of which is stable compared in particular to that of a vitreous support, its effectiveness will be preserved over time. In addition, it is not necessary to treat the surface intended to receive the decoration to promote adhesion and the film can be applied directly to the surface to be decorated.

Furthermore, the chemical reaction which takes place between the first compound present in the film and the second compound on the surface makes it possible to create a chemical bond which is relatively stable.

Preferably, the first compound is a silane or a silane derivative of chemical formula: ^ * OC n H 2n + 1 y ³ - Si - \ OC n H 2n + 1

OC n H, 2n + ₁ 1 where y is an organofunctional group capable of being grafted onto an organic polymer of the hot stamping film, for example on the adhesive. It is for example a carbon double bond; and where preferably, 0 <n <2. Such a compound makes it possible to create a covalent bond between the surface to be decorated and the hot marking film. Such a bond provides maximum bond energy.

According to one embodiment, the first compound is placed inside the first layer, namely in the adhesive layer, that is to say in the layer which comes directly into contact with the surface to be decorated. Thus, an optimal number of first compound can react with a second compound of the surface to be decorated. The first layer comprises, by weight, from 0.5 to 5% of the first compound, preferably from 1 to 3%.

According to another embodiment, the first compound is placed inside a layer adjacent to the first layer.

The first layer of the film, namely the adhesive layer which makes it possible to fix the decoration on the surface to be decorated, consists for example of a chlorinated rubber or of acrylic origin. This layer is hot-melt, and therefore allows the decoration to adhere to the surface under the effect of heat.

The second layer used to form the decoration is formed at least in part from a metallic material, for example aluminum. The second layer can also be at least partially formed from an organic material such as an ink, a pigment, etc. This second layer is advantageously covered, on the side opposite to the first layer, with a varnish. This varnish can be colored or not. It makes it possible to obtain a metallic or colored metallic rendering and also to protect the second metallic or organic layer.

The heat-sensitive material making it possible to fix the support on the second layer or on the layer of varnish, is advantageously a wax, a very low molecular weight polymer based on ethylene for example, or a silicone. It allows, when applying the film to the surface, to separate the support from the rest of the film by melting under the effect of heat. The film protection support consists of a thermoplastic film, in particular polyester. It helps protect the decor especially during the application of pressure and heat during transfer.

The objects of the invention are also achieved by producing an article, in particular of packaging, decorated with a film such as that described above. The surface of the article on which the film is affixed is glass, crystal, metal or ceramic. It is for example a glass bottle or an object, for example a container, covered with a metallic coating.

According to another aspect of the invention, the objects of the invention are achieved by carrying out a method for hot stamping a surface, in particular made of glass or metal, in which a film such as that described above is brought to the contact with said surface and pressure and heat are applied, in a humid environment, to at least one zone of the film corresponding to the decoration.

The heat must be such that it makes it possible to melt the heat-sensitive adhesive of the first layer in order to fix mechanically, using the pressure applied to the film, on the surface to be decorated. Preferably, pressure is applied to the film at a temperature ranging from 120 to 300 ° C. Such a temperature is sufficient to melt the adhesive relatively quickly while not being too high so as not to damage the film. On the other hand, the pressure exerted makes it possible to separate the support from the layer forming the decoration.

The wet medium makes it possible to obtain, for example from silane, silanols which, by condensing, will make it possible to create a covalent bond between the film and the surface according to a reaction which will be described later.

Advantageously, the hot stamping process is implemented in a humid environment with a humidity level greater than or equal to 50 HR. This humidity makes it possible to hydrolyze a sufficient number of first compounds for, for example in the case of silane, obtain a sufficient number of silanols capable of creating a covalent bond between the film and the surface.

The process is advantageously carried out in an acid medium so as to catalyze the reaction which makes it possible to create the covalent bonds between the film and the surface. May for example introduce small quantities acid in the composition intended to form the adhesive layer ^•. Alternatively, an acid composition is applied to the surface to be decorated before applying the hot stamping film.

The invention consists, apart from the arrangements set out above, of a certain number of other arrangements which will be explained below, with reference to nonlimiting exemplary embodiments, described with reference to the appended figures, among which:

FIGS. 1A to 1 C schematically describe the different stages of the hot stamping method using the hot stamping film according to an embodiment of the invention.

The hot stamping film 10 shown in particular in FIG. 1A is a structure which comprises several layers.

A first layer 11 of adhesive is formed from a hot-melt adhesive material. It is for example a chlorinated rubber. A first face of this first layer is intended to be applied to the surface 100 to be decorated. The second face of the adhesive layer 11 is covered with a second layer 12 formed of an aluminum sheet intended to form the decoration. The aluminum sheet 12 is advantageously covered with a layer of varnish 13 which can be colored, for example a resin. The varnish layer 13 is coated with a layer of wax 14 which is covered by a support 15, for example made of polyester.

A silane 20, for example a silane sold by the company Witco Corporation under the reference A1100, is included in the adhesive layer 11. Advantageously, a small amount of acid, for example hydrochloric acid, is introduced into the adhesive layer so as to obtain a pH ranging from 4 to 7, and preferably around 5. The amount of acid, in weight, in the adhesive layer ranges for example from 0.1 to 10%, preferably from 0.5 to 5%.

The decoration which will be applied to the surface to be decorated is relatively thin, which is why the different layers of the film which are intended to remain on the surface to be decorated are very thin. On the other hand, the polyester support 15 is relatively thick compared to the other layers so as to, on the one hand, consolidate the entire film before transfer and, on the other hand, protect the decoration during transfer. The support 15 has for example a thickness of the order of 12 μm. The wax layer 14 may have a thickness of the order of 0.01 μm, the varnish layer 13 a thickness of the order of 1 μm, the aluminum layer 12 a thickness of the order of 0.02 μm and the adhesive layer 11 has for example a thickness ranging from 0.8 to 3.50 μm.

To make such a film, a coating technique is used, including continuous vacuum metallization for metallic renderings and a printing process, for example gravure printing for ink or coloring varnishes. An equivalent printing process can be used to deposit the mixture of adhesive and silane in a surface layer.

The hot stamping film which has just been described is used in particular for decorating a glass object, such as for example a bottle.

To decorate the bottle, the film is brought into contact with the exterior surface of the bottle as illustrated in FIG. 1A, and pressure is applied to the film, using a hot browning iron 200, comprising reliefs corresponding to the decoration to be produced which is brought to the external face of the film support (FIG. 1B).

Iron 200, heated for example to 280 ° C., melts the chlorinated rubber in the zones corresponding to the decoration which is mechanically fixed on the bottle, thanks to the pressure applied by the iron. The chlorinated rubber is thus made integral with the bottle in the areas where the iron has been applied. The aluminum foil covered with varnish is also attached to the bottle in these areas since it remains attached to the rubber. Under the effect of heat and pressure, the wax provided between the varnish and the support facilitates the detachment of the polyester support from the rest of the film (FIG. 1C). The wax tends to remain on the support on which it was applied.

In addition, the film is brought into contact with the bottle in a humid environment with a humidity level of the order of 50% or more. The wet environment makes it possible to obtain silanols from the silane, according to the reaction:

. OC OH n H 2n + 1 + H ₂ O

If OC n H 2π + 1 y Si - OH + n CH ₃ OH

^"* \ 0H ^{0 C} n ^H 2n ₊₁

It is obvious that when n is equal to zero, this reaction does not take place since we are already in the presence of silanol.

The silanol will then condense and react with the active groups on the surface of the glass, for example the vitrifying agent SiOH4 so as to form a covalent bond with the glass of the bottle according to the reaction:

I

y— If i O - + H2O

The bonds thus obtained promote the adhesion of the film to the glass surface.

The film and the process which have just been described can also be used to transfer a decoration to an object covered with a metallic coating such as for example aluminum. In this case, there is a reaction with the AIOH3 group so as to form a covalent bond according to the reaction: OH II y— Si - OH + OH— Al - O Si - O - Al - O + H2O

^X OH 1 I

O

1

According to another embodiment, the second layer 12 of the film capable of forming the decoration is partly formed, on the one hand, of a metallic film and, on the other hand of an organic material, for example an ink. One can thus decorate, for example a bottle, with a first pattern formed by an ink, for example letters, and a second pattern having a metallic rendering.

To make such a film, the polyester support 15 is covered with a layer of wax 14 on which is deposited, for example by gravure printing, a layer of varnish 13, for example a polyurethane, which may or may not be colored. An organic ink is then deposited on the varnish layer 13 by a printing technique such as, for example, gravure printing. The negative corresponding to the first pattern formed by the ink which one wishes to obtain is printed in this way directly. Then deposited on the rest of the layer of varnish, except on an area corresponding to the negative of the second pattern, a layer of organic varnish on which the metallic material cannot adhere. The printed area of ink can itself be covered with organic varnish or else, in particular in the case where the ink does not itself allow the adhesion of the metallic material, one can dispense with covering it with this varnish . Then the entire film is coated with a metallic material by continuous vacuum metallization, the metallic material adhering only in the area which has not been coated with varnish and which corresponds to the negative of the second pattern. Finally, the whole is covered with a mixture 11 of adhesive and silane, for example by gravure printing.

Alternatively, to produce such a film, the polyester support 15 is covered with a layer of wax 14 on which a layer of varnish 13 is deposited, for example by gravure printing, which may or may not be colored. The ink is deposited on the varnish layer 13 by a printing technique, for example rotogravure, the negative corresponding to the first motif of the decoration which is wish to obtain being directly drawn on this layer of varnish. Then, a metal deposition is carried out under partial vacuum on a portion of the film which has not been printed with ink. This deposition is carried out by sputtering to precisely deposit the metal on the desired area corresponding to the second pattern of the decoration. Alternatively, the metal can be partially deposited before printing with ink. Finally, the assembly is covered with a mixture of adhesive and silane 11.

To decorate the bottle, the film is brought into contact with the exterior surface of the bottle, and pressure is applied to the areas of the film comprising the two patterns of the decoration, by means of a hot gilding iron which is brings on the outer face of the film support. The iron used is this time a solid iron which does not have any particular reliefs since the decoration is already formed on the film.

In the foregoing detailed description, reference has been made to preferred embodiments of the invention. It is obvious that variants can be made without departing from the spirit of the invention as claimed below.

Claims

1. Film (10) for decoration by hot stamping a surface (100), in particular made of glass or metal, the film comprising a first layer (11) of a heat-sensitive adhesive intended to be brought into contact with said surface, a second layer (12) of a material capable of forming said decoration, a protective support (15) fixed to the second layer by means of a layer (14) of a heat-sensitive material, characterized in that that the film comprises at least a first compound (20) capable of reacting chemically in a humid medium with at least a second compound of said surface (100) so as to promote the adhesion of the film during its application to said surface.

2. - Film according to claim 1, characterized the first compound (20) is a Silane or derivative of Silane.

3. - Film according to claim 1 or 2, characterized in that the first compound (20) is arranged inside the first layer (11).

4. - Film according to claim 3, characterized in that the first layer (11) comprises by weight, 0.5 to 5%, and preferably 1% to 3%, of said first compound (20).

5. - Film according to claim 1 or 2, characterized in that the first compound (20) is disposed inside a layer adjacent to the first layer (11).

6. - Film according to any one of the preceding claims, characterized in that the first layer (11) consists of a chlorinated rubber or of acrylic origin.

7. - Film according to any one of the preceding claims, characterized in that the second layer (12) is formed at least in part from a metallic material, in particular aluminum.

8. - Film according to any one of claims 1 to 7, characterized in that the second layer (12) is formed at least in part from an organic material, in particular pigment or ink.

9. - Film according to any one of the preceding claims, characterized in that the second layer (12), on the side opposite to the first layer (11), is covered with a varnish (13).

10. - Film according to any one of the preceding claims, characterized in that the heat-sensitive material (14) is a wax.

11. - Film according to any one of the preceding claims, characterized in that the protective support (15) consists of a thermoplastic film, in particular of polyester.

12. - Article, in particular of packaging, decorated by means of a film (10) according to any one of the preceding claims.

13. - Article according to claim 12, characterized in that the surface (100) of the article on which the film (10) is affixed is made of glass, crystal, metal or ceramic.

14. - A method for decorating by hot stamping a surface (100), in particular glass or metal, in which a film (10) according to any one of claims 1 to 11 is brought into contact with said surface (100) and a pressure and a heat are applied in a humid environment to at least one zone of the film corresponding to the decoration.

15. - Method according to claim 14, characterized in that it is implemented in a humid environment with a rate of hygrometry greater than or equal to 50 HR.

16. - Method according to any one of claims 14 or 15, characterized in that it is implemented at a temperature ranging from 120 to 300 ° C.

17. - Method according to any one of claims 14 to 16, characterized in that it is implemented in an acid medium.