FR2984529A1 - MIRROR COMPRISING A POLYMER-BASED REPORTED FILM - Google Patents

Abstract

The invention relates to a mirror comprising a protective coating against chemical attack, in particular corrosion and mechanical attack, such as, for example, scratches consisting of a polymer-based film and its method of manufacture. The protective film comprises at least one layer based on a polymer having a barrier effect to corrosion agents.

Description

The invention relates to a mirror comprising a protective coating 5 against chemical and mechanical aggression consisting of a polymer-based film and its method of manufacture. A mirror usually comprises a transparent and rigid substrate on which a reflective layer has been deposited. The reflective layer 10 often made of metal such as silver or aluminum tends to corrode in the ambient air due to the presence of pollutants in the atmosphere such as sulphides and chlorides and is therefore , necessary to protect it to increase its life. In most cases, one or more layers of paint are deposited on the silvering of the mirrors to protect them against chemical and / or external mechanical aggression. These paints are generally of the acrylic, alkyd, epoxy or polyurethane type. They most often contain significant amounts of inorganic or organic pigments and are usually fired in the factory at elevated temperatures, often above 170 ° C. In order to obtain a satisfactory quality for the desired applications, it is often necessary to also play on the cooking time. For example, patent application FR 2 936 240 describes a mirror comprising a protective coating combining two types of paint that do not contain lead, one being of alkyd type and the other of polyurethane type. US application 2009/0220685 proposes to apply a layer of epoxy paint on the silver substrate. The paints are generally solvent-based, which is not without problems at the sanitary and environmental level due to emissions of volatile organic compounds or VOCs, as well as at the level of safety (risk of fires) and costs (treatment and disposal of solvents). 2 9 84 52 9 2 Important problems are also encountered with regard to the durability of the products during their external exposure. The reduction in the level of lead currently imposed in paints is such that their durability is strongly impacted.

Another method of protecting the silvering layer is to laminate the mirror with a counter-glass or a metal foil, for example aluminum. A tie layer is generally used to facilitate the adhesion of both parties. Application EP 0882997 describes the use of a polyether-based polyether material as a binder layer. However the addition of a counter-glass or a metal sheet weighs the final product, makes it difficult to manipulate and transformable. In addition, to achieve the lamination, a PVB encapsulant film, with a thickness of the order of several hundred pm, must be used to erase the surface asperities, which poses problems of corrosion in the edges of the mirrors. The invention solves the aforementioned problems by proposing to cover the reflective layer with an attached film comprising at least one polymer-based layer protecting against corrosion and mechanical aggression such as scratches and to keep a light product and easy to cut. The mirror according to the present invention comprising a glass sheet and at least one reflecting layer, preferably metal, applied to the glass comprises an outer protective coating of the reflective layer against corrosion and mechanical aggression, consisting of an attached film whose thickness is between 5 and 500 μm, said film comprising at least one polymer-based layer.

For the purposes of the present invention, the added film forming the protective coating is manufactured independently of the mirror and is ready for use. It consists of one or more layers, stacked on top of each other. The protective coating is called "external" since it constitutes the outer face of the mirror, in contact with the ambient air. No layer or other coating is deposited on the outer protective coating. The thickness of the film is that measured once the protective film is applied to the mirror.

The reflective layer may be a layer of silver, aluminum, tin, chromium, copper or their alloys. The mirror may include at least one inorganic water and gas barrier layer between the reflective layer and the attached film. All polymers known to those skilled in the art and capable of forming films having a barrier effect to corrosion agents can be used as a base component of the reported film.

The film comprises at least one layer based on a polymer chosen from: polyesters, such as poly (ethyleneterephthalate) or PET, poly (ethylenenaphthalate) or PEN, polyglycolic acid or PGA, polylactic acid or PLA , poly (caprolactone) or PCL, poly (ethylene adipate) or PEA, poly (butylene terephthalate) or PBT, poly (trimethylene terephthalate) or PTT, poly (hydroxyalkanoate) or PHA, halogenated polymers such as polyvinyl chloride or PVC, polyvinyl fluoride or PVF, polyvinylidene fluoride or PVDF, polytetrafluoroethylene or PTFE, polychlorotrifluoroethylene or PCTFE, perfluoroalkoxy or PFA, ethylene tetrafluoroethylene or ETFE, fluorinated ethylene propylene or FEP, poly (ethylenechlorotrifluoroethylene) or ECTFE, perfluoropolyether or PFPE, polyvinylidene chloride or PVDC, polychloroprene, vinyl polymers such as, polyvinyl acetate ) or PVAC, polysty rene or PS, ethylene-vinyl acetate or EVA - acrylic polymers such as poly (methyl methacrylate) or PMMA, ethylene-ethyl acrylate or EEA, ethylene-methyl acrylate or EMA, - polyolefins such as polypropylene or PP, polyethylene or PE, poly (methylpentene) or PMP, polyisobutylene or PIB, polyamides or PA, polyimides or PI, polycarbonates, cellulose-based polymers such as cellulose hydrates or nitrates or - epoxy polymers. Corrosion agents include water, gases such as oxygen or SO2 and small molecules such as sulphides or chlorides. It is necessary that the protective film acts as a barrier layer to the corrosion agents. Depending on the polymer chosen from the above-mentioned list, the barrier effect on water, gases and / or small molecules will be more or less important. The material constituting the film may especially be characterized by a permeability to water vapor of less than 200 g.mm/m2/day, at a temperature of 25 ° C. and with a relative humidity of 95%, and a permeability to oxygen less than 100 g.mm/m2/day/atm, at a temperature of 23 ° C and with a relative humidity of 85%. The water and oxygen flow measurements are respectively performed according to ASTM F1249 and ASTM D3985. Advantageously, the variation of the permeability of the film as a function of the humidity is low. According to another embodiment, the attached film is a multilayer film 25 and further comprises at least one adhesion layer. The adhesion layer is the outer layer of the attached film which is directly in contact with the mirror and which allows the adhesion of the protective film to the mirror. The adhesion layer makes it possible to fix the attached film on the mirror. It may in particular consist of polymer and be for example polyvinyl butyral or PVB, copolymer of ethylene and vinyl acetate or EVA, polyurethane or PU, poly (methyl methacrylate) or PMMA, polyethylene or EP.

When the attached film is of the multilayer type, it may comprise, in addition to the adhesion layer, one or more inorganic layers, to improve the barrier properties against the corrosion agents. The inorganic layers may be metal layers, for example aluminum, or oxide layers such as silicon oxynitrides and / or silicon oxycarbides, and also silicon nitride layers. The protective film may possibly consist only of a single layer, if the latter plays both the role of adhesion layer and barrier layer. The attached film may for example be a polyethylene film. The thickness of the film is advantageously between 10 and 200 μm.

According to one embodiment, it is possible to use multilayer polymeric films in which at least one layer is optically active. Under the term "optically active" it is understood that the layer modifies the nature of the transmitted light. The layer may for example be colored and / or opaque. The added film protects the reflective layer of the mirrors, without using solvent. As a result, fire risks and volatile organic compound (VOC) emissions problems at the factory are limited.

The stacking possibilities of multilayers are numerous and the engineering developed around these layers is very important. The preformed films reported on the mirror are manufactured by conventional methods known to those skilled in the art. For example, the sheath blowing process (also called "film blowing" in English), or the flat film extrusion process (also called "film casting" in English).

Blow lines used in a sheath blowing process make it possible to produce multilayer structures. In general, three types of resin are used: a resin as a mechanical structure, a resin as a binder and a resin with barrier properties.

The molten polymer feeds an annular die. The tube obtained at the outlet of the die is stretched longitudinally and simultaneously air is blown into the interior, which produces a biaxial stretching. The inflated tube is cooled until the polymer reaches its crystallization temperature and solidifies. The resulting film passes through a roll system and is laid flat before being cut. Flat film extrusion involves extruding a polymer in the molten state through a flat die, stretching it in the air for a short distance and cooling it rapidly on a thermostatic roll. The resulting film is then stabilized on contact with successive rolls and then wound. Any inorganic layers are deposited by physical vapor deposition (PVD) or chemical vapor deposition (CVD) techniques. The protective film may be self-adhesive or heat-adhesive. The invention also relates to the method of manufacturing a mirror as described above. The method of manufacturing a mirror according to the present invention comprises the following steps: the deposition of a reflective layer on a glass sheet, optionally the deposition of at least one inorganic barrier layer to water and gases on the reflective layer, and applying the side of the reflective layer of a protective film comprising at least one polymer-based layer. The deposition of the reflective layer on the glass sheet is carried out by techniques known to those skilled in the art. We can mention the techniques of vapor deposition (CVD, PVD, magnetron) or wet. Optionally, depending on the deposition technique employed, a surface preparation may be performed. When the reflective layer is a silver layer, it typically has a thickness between 50 and 200 nm. According to one embodiment, an adhesion primer can be applied to the reflective layer or the inorganic barrier layer if it is present. This adhesion primer may be of silane type, coated, hot wax, resin, for example epoxy, paraffin, glue or any other type of material conventionally used to allow adhesion of a polymer-based film on a substrate .

The film is advantageously directly applied to the reflecting layer of the mirror. According to another embodiment, the film may be directly attached to an inorganic barrier layer, for example of the SiNx or SiOx type, possibly present on the reflecting layer of the mirror and deposited by conventional techniques such as CVD, PECVD (assisted) by plasma) or PVD (for example magnetron) as described in the patent application WO 2010/001061A2. In this case, it is possible to use a reported film whose barrier properties are lower. The adhesion primer, optionally present between the reflective layer or the inorganic barrier layer and the protective film, may be applied by liquid means.

The application of the film is performed by all the known techniques for depositing a flexible film on a rigid substrate.

In particular, the film can be applied by a lamination process, cold or hot depending on the nature of the adhesion layer if it is present. It can also be applied by a vacuum lamination process.

By way of example, when the film is applied by vacuum lamination, the lamination temperature is advantageously less than 200 ° C., preferably at a temperature of between 50 and 150 ° C. It is therefore possible to prepare the protective coating at temperatures below the temperatures usually used when the protective coatings are based on paint. If the film comprises a self-adhesive adhesion layer, the film adheres directly to the substrate at room temperature and does not require heat treatment. Advantageously, the application of the film is carried out in a vacuum chamber, which in particular makes it possible to eliminate the bubbles present between the mirror and the protective film. The problems associated with the deposition of the paint layers, which for example result in the formation of complex bubbles, heterogeneity and cleaning, can thus be avoided. The added film-based protective coating achieves excellent performance in protecting the reflective layer from corrosion and mechanical stress such as scratching. The product obtained remains light and easily transformable compared to rolled mirrors which comprise a counter-glass or a metal sheet. The mirrors according to the present invention can be used in the field of building, outdoors or indoors for domestic applications, as a solar mirror or in the automotive field. Example 2: A flat clear glass substrate of the silico-soda-lime type marketed under the trade name Planilux® by the applicant is coated with a layer of silver deposited by a silvering technique conventionally employed which consists in reducing chemically silver salts in solution, after sensitization of the substrate with a solution of SnCl2. This layer, whose thickness is 80 nm, almost completely reflects the visible radiation and can therefore be used as a mirror.

A multilayer film having a total thickness of 450 μm consisting of a 400 μm thick EVA adhesion layer and a 50 μm thick ETFE barrier layer cut to the dimensions of the mirror is placed between the mirror and a support against glass. The set is enclosed in a vacuum bag. Outside the pocket, the medium is maintained at atmospheric pressure. The temperature is maintained at 145 ° C for about 15 minutes, which allows the film to adhere to the mirror. The media is removed before cooling the system.

The permeance of the film with respect to the water vapor, taking into account its thickness is 0.2 / m2 / day. For comparison, for a paint layer of 100 μm, the permeance is 2000g / m2 / day. The corrosion tests were carried out after 120 hours in the salt spray test Cupro Acetic according to EN ISO 9227. The mirror comprising the protective film described above has in the face less than 2 bites of diameter less than 3 mm per dm2. As required by the EN 1036 standard, the protective film applied to the mirror 30 described above complies with the adhesion properties described in EN ISO 2409 with a value of less than 2, over a value ranging from 1 to 5 in which the optimal adhesion corresponds to the value 1.

Claims (14)

REVENDICATIONS1. Mirror comprising a glass sheet and at least one reflective layer, preferably metal, applied to the glass, characterized in that it comprises an outer protective coating of the reflective layer against corrosion and mechanical aggression consisting of a film reported, having a thickness of between 5 and 500 μm, said film comprising at least one polymer-based layer. 2. Mirror according to the preceding claim characterized in that it comprises at least one inorganic barrier layer to water and gas between the reflective layer and the attached film. 3. Mirror according to one of the preceding claims characterized in that the layer is based on a polymer selected from: - polyesters, such as poly (ethyleneterephthalate) or PET, poly (ethylenenaphthalate) or PEN, the acid polyglycolic or PGA, polylactic acid or PLA, poly (caprolactone) or PCL, poly (ethylene adipate) or PEA, poly (butylene terephatalate) or PBT, poly (trimethylene terephthalate) or PTT, poly (hydroxyalkanoate) or PHA, halogenated polymers such as polyvinyl chloride or PVC, polyvinyl fluoride or PVF, polyvinylidene fluoride or PVDF, poly (tetrafluoroethylene) or PTFE, poly ( chlorotrifluoroethylene or PCTFE, perfluoroalkoxy or PFA, ethylene tetrafluoroethylene or ETFE, fluorinated ethylene propylene or FEP, poly (ethylenechlorotrifluoroethylene) or ECTFE, perfluoropolyether or PFPE, polyvinylidene chloride or PVDC, polychloroprene, vinyl polymers such as, polyvinyl acetate or PVAC, polystyrene or PS, ethylene-vinyl acetate or EVA, acrylic polymers such as poly (methyl methacrylate) or PMMA, ethylene-ethyl acrylate or EEA, ethylene-methyl acrylate or EMA, polyolefins such as polypropylene or PP, polyethylene or PE, poly (methylpentene) or PMP, polyisobutylene or PIB, polyamides or PA, polyimides or PI, - polycarbonates, - cellulose-based polymers such as hydrates or cellulose nitrate or - epoxy polymers. 4. Mirror according to one of claims 1 to 3 characterized in that the attached film is a multilayer film and further comprises at least one adhesion layer. 5. Mirror according to one of claims 1 to 3 characterized in that it comprises a single layer playing both the role of adhesion layer and barrier layer. 6. Mirror according to claim 4 characterized in that the adhesion layer is polyvinyl butyral (PVB), copolymer of ethylene and vinyl acetate (EVA), polyurethane (PU), poly (methacrylate). methyl) (PMMA) or polyethylene (PE). 7. Mirror according to one of claims 4 to 6 characterized in that the added film further comprises one or more inorganic layers, such as metal layers, oxide layers and / or silicon nitride. 8. Mirror according to one of claims 4 to 7 characterized in that the reported film 25 comprises at least one optically active layer. 9. Mirror according to one of the preceding claims characterized in that the thickness of the reported film is between 10 and 200 pm. 30 10. A method of manufacturing a mirror according to one of the preceding claims comprising at least the following steps: - the deposition of a reflective layer on a glass sheet, - optionally the deposition of an inorganic barrier layer to the water and gases on the reflective layer, and applying the side of the reflective layer of a protective film comprising at least one polymer-based layer. 11. Method according to the preceding claim further comprising the application of an adhesion primer on the reflective layer or on the inorganic barrier layer if it is present. 12. The method of claim 10 wherein the film is applied directly to the reflective layer of the mirror. 13. The method of claim 10 wherein the film is applied directly to the inorganic barrier layer deposited on the reflective layer. 14. Method according to one of claims 10 to 13 wherein the application of the film is performed by a lamination process.