Lightweight mirror including a reinforcing layer

Abstract

The present invention relates to a mirror comprising a glass sheet coated on one of its faces with at least one reflective silver layer, at least one layer of paint and at least one reinforcing layer based on epoxy resin having a thickness greater than or equal to 100 µm, preferably between 100 µm and 5000 µm. The present invention also relates to a method for obtaining a mirror as defined above.

Description

Title of the invention: [TITLE OF THE INVENTION] Lightweight mirror comprising a reinforcing layer

[0001] The invention relates to the field of mirrors. It relates more particularly to specular mirrors, in which a user can admire themselves. Such mirrors are for example arranged inside homes, for example in bathrooms, or are used as elements of furniture (cupboard doors, etc.) or decoration. These mirrors generally comprise a sheet of glass coated on face 2 (the face opposite to that facing the user) with a reflective silver layer, which is coated with a layer of paint. The layer of paint has an optical function, that of preventing any visibility through the mirror by blocking the passage of light rays transmitted through the silver layer. The paint also has the function of protecting the silver layer against corrosion and mechanical attack.As is known, the paint layer can be coated with a thin layer generally less than 50 μm thick, which gives the mirrors specific properties.

[0002] The manufacture of mirrors and their transport (particularly due to their weight) generate numerous carbon dioxide (CO2) emissions, due to the presence of at least one sheet of glass within each mirror, which is harmful to the environment.

[0003] One solution to reduce the weight of mirrors and their carbon footprint is to reduce the thickness of the glass sheet. However, when only the thickness of the glass sheet of a mirror is reduced, a loss of mechanical resistance of the mirror is then observed, making it more fragile, which is not acceptable for the safety of people.

[0004] This is why the present invention aims to propose "lightweight" mirrors whose CO2 emissions are reduced, in particular during their manufacture and transport, while preserving their mechanical strength. In the present application, the term "lightweight" mirror means a mirror containing less glass and therefore lighter (in weight).

[0005] For this purpose, the invention relates to a mirror comprising a glass sheet coated on one of its faces with at least one reflective silver layer, at least one layer of paint and at least one reinforcing layer based on epoxy resin having a thickness greater than or equal to 100 μm, preferably between 100 μm and 5000 μm.

[0006] The inventors surprisingly discovered that it was possible to reduce the CO2 imprint of a mirror, while retaining good mechanical properties, by replacing part of the thickness of the glass sheet of said mirror with a material of lesser thickness than the thickness of said replaced glass; said material being an epoxy resin-based reinforcing layer having a thickness greater than or equal to 100 μm and arranged above the paint layer in a mirror.

[0007] The glass sheet is preferably a flat sheet, generally rectangular in shape. Preferably, the glass sheet has a dimension of at least 1 m, in particular at least 2 m. The thickness of each glass sheet is preferably within a range from 1 to 19 mm, in particular from 2 to 12 mm and even from 2 to 9 mm.

[0008] The glass is preferably a soda-lime-silica glass, but other types of glass such as borosilicates or aluminosilicates may be used. The glass is preferably obtained by floating. The glass is preferably colorless, but may be tinted, for example blue, green, gray, bronze, etc.

[0009] By the term "coated" is meant that the layer which coats the glass sheet or other layer is deposited on top of the glass sheet or other layer, but not necessarily in contact with them.

[0010] According to the invention, a reflective layer of silver is deposited above the glass sheet and advantageously by silvering. Silvering is understood to mean the process conventionally used for the manufacture of mirrors, and comprising the liquid deposition of a silver salt and a reducing agent.

[0011] Other processes are possible, such as magnetic field-assisted sputtering, frequently called the "magnetron process". The reflective silver layers thus obtained are, however, more sensitive to corrosion.

[0012] The silver reflective layer preferably has a physical thickness ranging from 50 to 200 nm, in particular from 50 to 100 nm, or even from 60 to 90 nm.

[0013] The mirror is preferably "copper-free" in the sense that the silver reflective layer is not covered by a copper layer.

[0014] According to the invention, a layer of paint is deposited above the silver reflective layer. A layer of paint is understood to mean a layer comprising at least one resin and at least one mineral filler, including at least one pigment. The layer of paint is preferably obtained by depositing a liquid paint composition generally comprising a solvent in addition to the resin and the mineral fillers, then drying the layer obtained. Drying involves the evaporation of a large part of the solvent. In certain cases, when the paint must be crosslinked, the layer of paint must also be baked. A distinction is then made between drying, in which the solvent evaporates, the resin not having begun to crosslink, and baking, in which the crosslinking resin.

[0015] The paint layer preferably comprises 20% to 80%, in particular 20% to 50% by weight of resins and 20% to 80%, in particular 30% to 80% by weight of mineral fillers.

[0016] The liquid paint is preferably water-based or solvent-free. By "water-based" is meant that the liquid paint comprises less than 10%, in particular less than 5% by weight of organic solvent, or even does not comprise organic solvents. The weight percentage of dry extract of the liquid paint is preferably at least 50%, or even at least 60%, in particular 60% to 70% in the case of water-based liquid paints. It may be 100% in the case of solvent-free liquid paint.

[0017] At least one resin of the paint layer is preferably chosen from acrylic resins, polyurethane resins, epoxy resins and alkyd resins.

[0018] The liquid paint is preferably based on an aqueous dispersion of an epoxy resin crosslinked with melamine. In the case of mirrors, such a paint has proven effective in protecting the underlying silver layer against corrosion.

[0019] At least one mineral filler in the paint layer is advantageously chosen from zinc oxide, barium sulfate, zinc phosphates, in particular zinc orthophosphate, talc, calcium carbonate, mica, titanium oxide, carbon black and mixtures thereof. The mineral fillers make it possible to improve the corrosion resistance of the silver layer and / or to obtain the desired opacity or shade.

[0020] The paint layer preferably does not contain lead. The paint layer may further comprise various additives, such as antifoaming agents, biocides or surfactants.

[0021] In the case of mirrors, for which the paint layer is not visible in the final application, the pigment is preferably carbon black, which makes it possible to obtain good opacity for low thicknesses.

[0022] The paint layer has a thickness preferably in the range of 20 to 100 μm, in particular 30 to 80 μm, or even 40 to 70 μm. High thicknesses may be necessary in the case where corrosion protection properties are required. This refers to the thickness of the layer in the final product.

[0023] The liquid paint layer is preferably applied by curtain, spray or roller. It can be applied in several passes.

[0024] The silver reflective layer, as described above, is preferably deposited directly on the glass sheet, with the exception of the layers resulting from the surface treatments conventionally used in the silvering process, when the silver layer is deposited by this process. In the latter case, it is advantageous to treat the glass sheet with a solution containing tin and palladium chlorides before depositing the silver layer. Similarly, before depositing the paint layer described above, the surface of the silver layer is preferably treated with a solution containing tin chloride and with aminosilanes. These treatments can form extremely thin layers detectable only by advanced analytical techniques.

[0025] Thus, the silver layer is preferably substantially in contact with the glass sheet, and / or the paint layer is substantially in contact with the silver layer, in the sense that only the aforementioned surface treatments could be carried out.

[0026] The epoxy resin-based reinforcing layer is placed above the paint layer and is preferably the outermost layer located on the back of the mirror, in other words it is preferably the layer in contact with the ambient air. In a preferred embodiment, the reinforcing layer is in direct contact with the paint layer. According to the invention, the reinforcing layer is an epoxy resin which has a thickness greater than or equal to 100 μm, preferably greater than or equal to 200 μm, more preferably greater than or equal to 400 μm and even more preferably greater than or equal to 500 μm. Even more advantageously, the reinforcing layer has a thickness of between 100 μm and 5000 μm, preferably between 100 μm and 3000 μm and more preferably between 100 μm and 1000 μm.The choice of the thickness of the epoxy-based reinforcement layer, according to the invention, makes it possible to reduce the CO2 impact of a mirror, while retaining good mechanical properties.

[0027] Furthermore, the choice of the material of the epoxy resin-based reinforcing layer is guided by the fact that this type of resin belongs to the family of polymers and that it is not necessary for said layer to give the mirror any chemical functionality. The essential role of the reinforcing layer in the present invention is to replace a part of the glass contained in a mirror and to improve the mechanical properties of said mirror, thus causing a reduction in its carbon impact, a lightening of said mirror and a reduction in transport costs.

[0028] Furthermore, the inventors have found that a reinforcing layer, specifically based on epoxy resin, makes it possible to obtain mirrors having better mechanical properties than a resin layer formed from other families of polymers such as acrylic, vinyl, polyurethane, polyester, alkyd or styrene resins.

[0029] Preferably, the epoxy resin of the reinforcing layer is formed from of a composition comprising a mixture:

[0030] - of a component A comprising an epoxy resin, - a component B comprising a hardener, which is a compound comprising at least one NH or SH function or a mixture of several of these compounds, in which the molar ratio R between the total number of epoxide groups in component A and the total number of NH and SH functions in component B is greater than or equal to 0.8.

[0031] It has proven particularly advantageous to use an epoxy resin formed by the above-mentioned composition, as a reinforcing layer of a mirror, since it has good reactivity at room temperature because it is a solvent-free liquid epoxy resin which does not need to be subjected to any evaporation. In addition, this particular epoxy resin makes it possible to avoid the release of carcinogenic / mutagenic / reprotoxic monomers and makes it possible to give the mirror better mechanical resistance.

[0032] By hardener is meant a compound, called hardener compound, comprising at least one NH or SH function or where appropriate a mixture of several of these compounds. In the latter case, the term “hardener” encompasses all of these compounds.

[0033] The term “epoxy resin” means a monomer or pre-polymer comprising at least least two epoxide groups or a mixture of such monomers or prepolymers. It may typically comprise two or three epoxide groups. The epoxy resin is preferably capable of being derived from the reaction between epichlorohydrin and at least one polyol. The at least one polyol is preferably chosen from saturated, unsaturated, branched, linear or cyclic polyols, in particular bisphenol A, bisphenol F, novolac resins, ethylene glycol, propylene glycol, butylene glycol, hexanediol, polypropylene glycols, polyethylene glycols, dimethylolcyclohexane and castor oil.

[0034] In calculating the ratio R, the total number (in moles) of epoxide groups in component A is taken into account. These are therefore the epoxide groups of the epoxy resins, but also, where appropriate, any epoxide groups contained in other constituents of component A, for example in reactive diluents, described in more detail in the rest of the text.

[0035] The or each hardening compound, which comprises at least one NH function (primary or secondary amine functions) or SH function (thiol functions), is capable of reacting with the epoxy groups of the epoxy resin by forming covalent bonds, and at the end of the reaction, a thermosetting polymer in the form of a three-dimensional network.

[0036] Preferably, the hardener comprises (or consists of) a compound comprising at least at least one NH function. The hardener can also consist of a mixture of compounds comprising at least one NH function. Amines are in fact preferred to thiols because the latter generally have a strong and unpleasant odor.

[0037] The or each hardening compound preferably comprises at least two, or even four or even six NH functions. A primary amine group (NH2) counts in the calculation of the ratio R as two NH functions. A diamine comprising two primary amine groups therefore counts as four NH functions.

[0038] Preferably, the hardener comprises a polyamine, i.e. a chemical compound comprising at least two amine groups. It may, for example, be a diamine or a triamine. The amine groups are primary amines (accounting for two NH functions) or secondary amines (possessing a single NH function). They are advantageously primary amine groups. Primary amines can in fact react with two epoxide groups, while secondary amines can only react with a single epoxide group.

[0039] The hardener is advantageously chosen from the group formed by aliphatic polyamines, cycloaliphatic polyamines, arylaliphatic polyamines, aromatic polyamines, polyamines containing at least one ether group, polyamidoamines, phenalkamines or Mannich bases, fatty amines, adducts of these polyamines with epoxy resins, and mixtures of two or more of these polyamines.

[0040] The aliphatic polyamines are in particular chosen from 2,2-dimethyl-1,3-propanediamine, 1,3-pentanediamine, 1,5-pentanediamine, 1,5-diamino-2-methylpentane, 2-butyl-2-ethyl-1,5-pentanediamine, 1,6-hexanediamine, 2,5-dimethyl-1,6-hexanediamine, 2,2,4- and 2,4,4-trimethylhexamethylenediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 3-(2-aminoethyl)-aminopropylamine, bis-(hexamethylene)-triamine, diethylenetriamine, triethylenetetramine, tetraethylene pentamine, pentaethylenehexamine and other homologs of linear polyethylene amines having 5 or more ethylene amine units.

[0041] The cycloaliphatic polyamines are in particular chosen from 1,2-, 1,3- and 1,4-diaminocyclohexane, bis-(4-aminocyclohexyl)-methane, bis-(4-amino-3-methylcyclohexyl)-methane, bis-(4-amino-3-ethylcyclohexyl)-methane, bis-(4-amino-3,5-dimethylcyclohexyl)-methane, bis-(4-amino-3-ethyl-5-methylcyclohexyl)-methane, l-amino-3-aminomethyl-3,5,5-trimethylcyclohexane(isophoronediamine), 2- and 4-methyl-l,3-diaminocyclohexane, 1,3- and l,4-bis-(aminomethyl)-cyclohexane, l,4-diamino-2,2,6-trimethylcyclohexane.

[0042] Arylaliphatic polyamines include 1,3- and 1,4-bis-(aminomethyl)-benzene.

[0043] Polyamines containing at least one ether group are known in particular under the trade name Jeffamine® (Huntsman) or Polyetheramine (BASF) or PC Amine® (Nitroil). Mention may be made in particular of polyalkylene diamines such as Jeffamine D-230®, Jeffamine® D-400, Jeffamine® D-2000, Jeffamine® EDR-104, Jeffamine® EDR-148 and Jeffamine® EDR-176 and the corresponding polyamines from BASF and Nitroil, as well as polyalkylene triamines such as in particular Jeffamine® T403, Jeffamine® T-3000, Jeffamine® T-5000 and the corresponding polyamines from BASF and Nitroil.

[0044] The aromatic polyamines are in particular chosen from m- and p-phenylenediamine, 4,4', 2,4' and 2,2'-diaminodiphenylmethane, 3,3'-dichloro-4,4'-diaminodiphenylmethane, 2,4- and 2,6-toluenediamine, mixtures of 3,5-dimethylthio-2,4- and 2,6-toluylenediamine (marketed under the reference Ethacure® 300 by the company Albemarle), mixtures of 3,5-diethyl-2,4- and -2,6-toluylenediamine, 3,3',5,5'-tetraethyl-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetraethyl-2,2'-dichloro-4,4'-diaminodiphenylmethane, 3,3'-diisopropyl 5,5'-dimethyl-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetraisopropyl-4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 4-amino-N-(4-aminophenyl)-benzenesulfonamide, 5,5'-methylenedianthranilic acid, dimethyl-(5,5'-methylenedianthranilate), l,3-propylene-bis-(4-aminobenzoate), l,4-butylene-bis-(4-aminobenzoate),poly-tetramethyleneoxide-bis-(4-aminobenzoate) (marketed under the reference Versalink® by the company Evonik), 1,2-bis (2-aminophenylthio)-ethane, 2-methylpropyl-(4-chloro-3,5-diaminobenzoate) and tert-butyl-(4-chloro-3,5-diaminobenzoate).

[0045] The polyamidoamines are preferably reaction products of a monofunctional or polyfunctional carboxylic acid or their esters or anhydrides, in particular fatty acids, with an aliphatic, cycloaliphatic, arylaliphatic or aromatic polyamine (in particular a polyalkyleneamine such as diethylenetriamine or triethylenetetramine) used in stoichiometric excess. These products are in particular commercially available under the name polyamidoamines Versamid® 100, 125, 140 and 150 (Cognis), Aradur R 223, 250 and 848 (Huntsman), Euretek® 3607 and 530 (from Huntsman) and Beckopox®, EH 651, EH 654, EH 655, EH 661 and EH 663 (Cytec).

[0046] Phenalkamines, also known as Mannich bases, are the products of the reaction of phenol derivatives with aldehydes, in particular formaldehyde, and polyamines. Mention will be made in particular of commercial Mannich bases Cially available as Cardolite® NC-541, NC-557, NC-558, NC-566, Lite 2001 and Lite 2002(Cardolite), Aradur R. 3440, 3441, 3442 and 3460(Huntsman) and Beckopox ®, EH 614, EH 621, EH 624, EH 628 and EH 629 (Cytec).

[0047] The fatty amines are preferably N-cocoalkyl-1,3-propanediamine and the products of a Michael type reaction of primary amines with acrylonitrile, maleic, fumaric, citraconic diesters, acrylic and methacrylic esters, acrylic and methacrylic amides and itaconic diesters, reacted with a molar ratio of 1:1.

[0048] Adducts of the above-mentioned polyamines with epoxy resins are in particular adducts with diepoxides in a molar ratio of approximately 2 / 1, adducts with monoepoxides with a molar ratio of at least 1 / 1 and reaction products of polyamines with epichlorohydrin known for example under the name Gaskamine® 328 (MGC).

[0049] In calculating the ratio R, the total number (in moles) of NH (and / or SH) functions in component B is taken into account.

[0050] The ratio R reflects the ratio between the number of epoxide functions and the number of NH (and / or SH) functions, capable of reacting with these epoxide functions. A ratio of 1 (stoichiometric) or very slightly greater than 1 is traditionally chosen so as to allow a complete reaction, while limiting, in the final polymer, the presence of unreacted amines (which can negatively impact certain properties such as resistance to solvents or stains). According to the invention, this ratio is therefore unusually high.

[0051] The ratio R is greater than or equal to 0.8, preferably between 0.8 and 2.0, more preferably between 0.8 and 1.5, and even more preferably between 0.8 and 1.2. Despite these high ratios, the level of unreacted epoxide groups at the end of the reaction is very low, as demonstrated below.

[0052] The ratio R can in particular be calculated from the equivalent weights of epoxides and the equivalent weights of active hydrogen of the compounds used.

[0053] The equivalent weight of epoxides of a compound i comprising at least one epoxide function, noted EEW; (for Epoxy Equivalent Weight) corresponds to the mass of compound i providing one mole of epoxide functions.

[0054] The equivalent weight of epoxides of component A (EEW) is then defined by the following formula:

[0055] [Math.l] 100 EWt;

[0056] wh being the mass percentage of compound i in component A.

[0057] The equivalent weight in active hydrogen of a compound j, noted AHEWj (for Amine Hydrogen Equivalent Weight) corresponds to the mass of compound j providing one mole of active hydrogen.

[0058] The active hydrogen equivalent weight of component B (AHEW) is then defined by the following formula:

[0059] [Math.2] AHEW = AHEW,

[0060] wtj being the mass percentage of compound j in component B.

[0061] The ratio R can then be calculated using the following formula:

[0062] [Math.3] R _ mA AHEW IV~ mB ' EEW

[0063] mA and mB being respectively the mass of component A and the mass of component B in the composition.

[0064] Without wishing to be bound by any scientific theory, it would seem that the presence of catalyst in high concentration, in combination with a high R ratio, promotes homopolymerization reactions of the epoxy resins with each other, making it possible to obtain, even after curing at room temperature, a polymer having both excellent mechanical resistance, in particular in compression, and excellent chemical resistance, in particular to stains.

[0065] Advantageously, component B of the composition forming the epoxy resin further comprises a catalyst which is a compound comprising at least one tertiary amine group or a mixture of several of these compounds.

[0066] The catalyst, or at least one catalyst compound, may in certain cases itself contain NH or SH functions, in which case the catalyst (or catalyst compound) is also a hardener (or hardener compound), these functions being taken into account in the calculation of the ratio R.

[0067] The catalyst is preferably chosen from the group formed by tertiary amines not containing an NH function (in particular phenols containing at least one tertiary amine group and imidazole derivatives not containing an NH function), amines and polyamines containing at least one tertiary amine group and at least one NH function, and mixtures of two or more of these compounds.

[0068] Tertiary amines not having an NH function are preferably chosen from 1,4-diazabicyclo[2.2.2]octane, benzyldimethylamine, triethanolamine, triethylamine, dimethylaminopropylamine, pyridine, 1,8-diaza-bicyclo[5.4.0]undec-7-ene, methylbenzyldimethylamine, phenols containing one or more tertiary amine groups, in particular 2-(dimethylaminomethyl)-phenol (known as DMP-10) or 2,4,6-tris-(dimethylaminomethyl)-phenol (DMP-30 or Ancamine® K54 from Evonik), and imidazole derivatives not containing an NH function, in particular N-methylimidazole, N-butylimidazole, N-vinylimidazole or 1,2-dimethylimidazole.

[0069] The amines or polyamines containing at least one tertiary amine group are preferably chosen from N,N'-bis-(aminopropyl)-piperazine, N,N-bis-(3-aminopropyl)-methylamine, N,N-bis-(3-aminopropyl)-ethylamine, N,N-bis-(3-aminopropyl)-propylamine, NN-bis-(3-aminopropyl)-cyclohexylamine, N,N-bis-(3-aminopropyl)-2-ethylhexylamine or N,N-bis-(3-aminopropyl)-dodecylamine (available under the name Triameen® Y12D from Akzo Nobel), imidazoles such as benzimidazole, 2-ethyl-4-methyl imidazole, or guanidines such as in particular 1,1,3,3-tetramethylguanidine or cyanoguanidine. (dicyandiamide).

[0070] According to a preferred embodiment, at least one of said component A and said component B comprises at least one mineral filler.

[0071] Mineral fillers make it possible to reduce the cost of the formulation and possibly improve certain properties, such as abrasion resistance.

[0072] Preferably, component A comprises at least one mineral filler. In this case, component B may not comprise a mineral filler, or may comprise a mineral filler, identical to or different from that of component A. According to a second embodiment, component B comprises at least one mineral filler. In this case, component A may not comprise a mineral filler, but preferably comprises a mineral filler, identical to or different from that of component B. The important thing is that the reinforcing layer, after mixing the two components, comprises at least one mineral filler.

[0073] Preferably, only component A comprises at least one mineral filler.

[0074] Advantageously, at least one mineral filler is chosen from carbonate of calcium, sand, silica, quartz, talc, kaolin, barium sulfate, aluminum oxides, metal powders and expanded glass (e.g. Poraver®).

[0075] Alternatively, the composition according to the invention may not comprise mineral fillers.

[0076] Component A and / or component B may comprise at least one mineral pigment, for example titanium dioxide or iron oxides, or organic pigment. Colored sands may however advantageously replace the pigments. The pigments make it possible to adapt the aesthetic appearance of the reinforcement layer, in particular the coloring and opacity.

[0077] Component A and / or component B may also comprise at least one additive, in particular chosen from accelerators, diluents, reactive (for example compounds having a single epoxide group) or non-reactive (for example compounds solvents), defoaming agents, rheology agents (in particular thickening or thixotropic agents), coalescing agents, dispersing agents, leveling agents, wetting agents, adhesion promoters, stabilizing agents against oxidation, heat or UV radiation, flame retardants (in particular halogenated or phosphorus derivatives).

[0078] Accelerators are used to accelerate the reaction between epoxy resins and hardeners. However, accelerators are not necessary because the catalyst also plays this role. When present, at least one accelerator is preferably chosen from acids, alcohols and phenol derivatives. The acids are in particular carboxylic acids, sulfonic acids or inorganic acids (in particular phosphoric acid). The carboxylic acids include in particular acetic acid, benzoic acid, salicylic acid, 2-nitrobenzoic acid, lactic acid. The sulfonic acids preferably include methanesulfonic acid, p-toluenesulfonic acid or 4-dodecylbenzenesulfonic acid. The alcohols are in particular methanol or polyols, such as ethylene glycol or glycerol.Phenol derivatives include bisphenol A, resorcinol, and halogenated phenol derivatives such as p-bromophenol, p-chlorophenol, and nitrophenols such as 2,4-dinitrophenol.

[0079] When present, the reactive diluent is normally included only in component A. Non-reactive diluents may be included in component A and / or in component B. The diluent is useful in order to reduce the viscosity of the mixture and therefore to allow easy application of the reinforcement layer.

[0080] The reactive diluent preferably comprises at least one epoxide group. It is preferably chosen from (poly)glycidyl ethers of aliphatic, cycloaliphatic or aromatic alcohols, in particular from phenyl glycidyl ether, cresyl glycidyl ether, benzyl glycidyl ether, pn-butyl-phenylglycidyl ether, p-tert-butyl-phenyl glycidyl ether, nonyl phenyl glycidyl ether, allyl glycidyl ether, butyl glycidyl ether, hexyl glycidyl ether and 2-ethylhexyl glycidyl ether.

[0081] Component A comprises, or even essentially consists of, at least one epoxy resin, generally at least one mineral filler, and optionally at least one additive (in particular at least one diluent). Component B comprises, or even essentially consists of, the catalyst, the hardener, and optionally at least one mineral filler and / or at least one additive.

[0082] When the composition contains mineral fillers, the mass proportion of mineral fillers in the composition according to the invention is preferably within a range from 20 to 90%, in particular from 30 to 80%. Preferably, at least 75%, in particular 90% by weight, or even all, of the mineral fillers in the com- position are part of component A.

[0083] The mass proportion of pigments in the composition is preferably within a range from 0 to 10%, in particular from 1 to 8%. The pigment may be present in component A and / or component B, preferably only in component A.

[0084] The mass proportion of epoxy resin in the composition is preferably within a range from 5 to 90%, in particular from 10 to 80%, or even from 20 to 60%. The epoxy resin is normally only found in component A.

[0085] The catalyst and hardener are normally only found in component B, in order to avoid any premature reaction.

[0086] The mass proportion of other additives in the composition is preferably within a range from 0 to 25%, in particular from 1 to 20%, or even from 2 to 10% or even from 2 to 5%. The additives can be distributed between component A and component B.

[0087] In the composition according to the invention, the respective mass proportions of component A and component B (A:B) preferably vary from 60:40 to 95:5, in particular from 80:20 to 93:7.

[0088] The invention also relates to a method for obtaining such a mirror comprising the following steps: - the supply of a sheet of glass, - the deposition of at least one reflective silver layer, - the application of at least one layer of paint, - the deposition of at least one reinforcing layer based on epoxy resin having a thickness greater than or equal to 100 pm, preferably between 100 pm and 5000 pm.

[0089] As explained above, the step of depositing the reflective silver layer above one of the glass sheets is advantageously carried out by silvering and the liquid paint layer is preferably deposited by curtain, spraying or roller and / or in several passes.

[0090] Preferably, the step of depositing the reinforcing layer is carried out by liquid means by spraying, by roller, by dipping, by curtain coating or by sprinkling or by film puller, or by screen printing techniques.

[0091] In the preferred embodiment, in which the reinforcing layer is an epoxy resin formed from a composition comprising a mixture of a component A and a component B, the application to the paint layer of the mixture, obtained after manual mixing of the two components or by means of a mixer, can be carried out in a known manner by means of a brush, a roller or a paintbrush, a spatula, or by spraying.

[0092] Examples

[0093] The following examples illustrate the invention in a non-limiting manner.

[0094] Two different resins were tested to form the reinforcement layer: - resin A: polyurethane PU resin (comparative test, noted Cl below), in latex form (Easysafe marketed by the Applicant), - resin B: epoxy resin (tests according to the invention, noted E1, E2 below).

[0095] Epoxy resin B was formed from a composition comprising 100 g of component A per 29 g of component B.

[0096] Component A comprises 93% by weight of a mixture of bisphenol A diglycidyl ether and bisphenol F diglycidyl ether resin and 5% by weight of a C12-C14 alcohol glycidyl ether reactive diluent, and 2% by weight of additives (defoaming and leveling agents).

[0097] Component B comprises: - 2% of a catalyst which is the product Jointmine NO-30 from the company Epochemie containing 2,4,6-tris(dimethylaminomethyl)phenol, which comprises three tertiary amine groups and a phenol group, and - a hardener containing a mixture of 80% by weight of polyetheramine (Jeffamine D-230, Hunstmann, AHEW = 60g / eq.) and 18% by weight of pure isophorone diamine (Sigma, AHEW = 42g / eq).

[0098] The molar ratio R between the total number of epoxide groups in component A and the total number of NH and SH functions in component B is equal to 1.1.

[0099] Resin A was applied using a film puller and then scraped onto a mirror (mirror comprising a glass sheet coated on one of its faces with a reflective silver layer, with a layer of paint) and the thickness of the glass sheet being 2 mm, to form a reinforcing layer with a thickness equal to 500 μm (comparative test, noted Cl).

[0100] Resin B was applied using a film puller and then scraped, onto a mirror (mirror comprising a glass sheet coated on one of its faces with a reflective silver layer, with a layer of paint) and the thickness of the glass sheet being 2 mm, to form a reinforcing layer of different thicknesses: 500 μm and 1000 μm (tests according to the invention, noted E1 and E2).

[0101] These resins were then compared with each other and compared with a mirror not comprising a reinforcing layer but whose glass sheet has different thicknesses: 2 mm and 3 mm (reference tests, noted RI and R2 respectively below).

[0102] The mechanical strength of the mirrors (or mechanical properties of the mirrors) with or without a reinforcing layer was evaluated in two different ways.

[0103] According to a first method, the mechanical strength was evaluated by the bending test 3 points (slow speed test), according to ISO 178, on mirror samples comprising a glass sheet with dimensions of 300 x 50 mm with a bending distance of 250 mm at a test speed of 5 mm / min. This method allows the breaking force to be obtained.

[0104] According to a second method, the mechanical strength was evaluated by the Charpy sheep test (fast speed test), according to ISO 148-1 standard to obtain the breaking energy. For this, mirror samples comprising a glass sheet of dimensions 60 x 60 mm were tested with a hammer weight of 250 g and an arm length of 300 mm.

[0105] For each of the tests, the reinforcing layer was deposited on the glass sheet, in particular on the paint layer of the mirror, on face 2 (the face opposite to that facing the user, coated glass sheet side) and the stress point of the bending tests was located on face 1 (face facing the user, uncoated glass sheet side).

[0106] Table 1 below indicates for each test the breaking force obtained according to the 3-point bending test mentioned above:

[0107] [Tableauxl] Mirror tests with reinforcement layer Resin type for reinforcement layer Thickness of glass sheet (in mm) Thickness of reinforcement layer (in mm) Force at break (in N) RI (reference) — — 2 mm — 28 R2 (reference) — — 3 mm — 59 El (invention) yes resin B (epoxy) 2 mm 500 pm 67 E2 (invention) yes resin B (epoxy) 2 mm 1000 pm 82 Cl (comparative) yes resin A (PU) 2 mm 500 pm 45

[0108] Table 1 shows an increase in breaking force with increasing glass sheet thickness (for RI, 2 mm = 28 N vs. R2, 3 mm = 59 N).

[0109] It is noted that the addition of a reinforcement layer based on polyurethane resin (resin A) having a thickness equal to 500 μm (in wet deposition) above a sheet of 2 mm thick glass only causes a slight increase in the breaking force (from Rl = 28N to Cl = 45 N).

[0110] On the contrary, it is found that the addition of a reinforcing layer based on epoxy resin (resin B) having a thickness equal to 500 μm and equal to 1000 μm above a 2 mm thick glass sheet results in a significant increase in the breaking force (from RI = 28 N to El = 67 N and E2 = 82 N). This breaking force is also greater than that of a 3 mm thick glass sheet not coated with a reinforcing layer (R2 = 59 N).

[0111] Consequently, it is found that replacing a glass thickness of 1 mm with a reinforcing layer comprising an epoxy resin, half as thick, i.e. having a thickness of 500 μm (El = 67 N / R2 = 59 N) makes it possible to improve the mechanical properties of a mirror and thus makes it possible to obtain a lighter mirror.

[0112] In addition, a 3 mm thick sheet of glass corresponds to a Global Warming Potential (GWP) of 8.17 kg CO2 eq / m2, while a 2 mm thick sheet of glass plus the addition of the 500 pm (0.5 mm) thick epoxy resin reinforcement layer corresponds to a GWP of 7.46 kg CO2 eq / m2. This therefore corresponds to a saving of 0.5 kg CO2 eq / m2. This value does not take into account the reduction in the total weight of the glass, which would further reduce the carbon footprint during transport. Therefore, replacing a 1 mm glass thickness with a reinforcing layer comprising an epoxy resin, half as thick, i.e. having a thickness of 500 pm also makes it possible to reduce the CO2 impact.

[0113] Table 2 below indicates for each test the breaking energy obtained according to the Charpy sheep test mentioned above:

[0114] [T ables 2] Mirror tests with reinforcement layer Resin type Thickness of the glass sheet (in mm) Thickness of the reinforcement layer (in mm) Breaking energy (in J) RI (reference) — — 2 mm — 0.14 R2 (reference) — — 3 mm — 0.18 El (invention) yes resin B (epoxy) 2 mm 500 pm 0.23 Cl (comparative) yes resin A (PU) 2 mm 500 pm 0.15

[0115] It is found that the addition of a reinforcing layer based on epoxy resin (resin B) having a thickness equal to 500 μm above a 2 mm thick glass sheet results in a significant increase in the breaking energy (from 0.14 J (RI) to 0.23 J (El)). This breaking energy is also greater than that of a 3 mm glass sheet not coated with a reinforcing layer (R2 = 0.18 J).

[0116] On the other hand, the addition of a reinforcing layer based on polyurethane resin (resin A) having a thickness equal to 500 μm above a 2 mm thick glass sheet hardly improves the impact resistance since Cl = 0.15 J and RI = 0.14 J.

[0117] Therefore, the table shows that the reinforcing layer, specifically based on epoxy resin, allows obtaining a mirror having better mechanical properties than a reinforcing layer based on polyurethane resin.

Claims

Claims

1. Mirror comprising a glass sheet coated on one of its faces with at least one silver reflective layer, at least one paint layer and at least one epoxy resin-based reinforcing layer having a thickness greater than or equal to 100 pm, preferably between 100 pm and 5000 pm.

2. Mirror according to claim 1, wherein the epoxy resin of the reinforcing layer is formed from a composition comprising a mixture of: - a component A comprising an epoxy resin, - a component B comprising a hardener, which is a compound comprising at least one NH or SH function or a mixture of several of these compounds, wherein the molar ratio R between the total number of epoxy groups in component A and the total number of NH and SH functions in component B is greater than or equal to 0.8, preferably between 0.8 and 2.

0.

3. Mirror according to claim 2, in which the hardener comprises a compound comprising at least one NH function.

4. Mirror according to claim 3, wherein the hardener is selected from the group consisting of aliphatic polyamines, cycloaliphatic polyamines, arylaliphatic polyamines, aromatic polyamines, polyamines containing at least one ether group, polyamidoamines, phenalkamines, fatty amines, adducts of these polyamines with epoxy resins, and mixtures of two or more of these polyamines.

5. Mirror according to one of claims 2 to 4, wherein component B further comprises a catalyst which is a compound comprising at least one tertiary amine group or a mixture of several of these compounds.

6. Mirror according to claim 5, in which the catalyst is chosen from the group formed by tertiary amines not containing an NH function, amines and polyamines containing at least one tertiary amine group and at least one NH function, and mixtures of two or more of these compounds.

7. Mirror according to one of claims 2 to 6, wherein at least one of said component A and said component B comprises at least one mineral filler.

8. Mirror according to claim 7, in which only component A comprises at least one mineral filler.

9. Mirror according to one of claims 7 or 8, such that at least one mineral filler is chosen from calcium carbonate, sand, silica, quartz, talc, barium sulfate, kaolin, aluminum oxides, metal powders and expanded glass.

10. Mirror according to one of claims 7 to 9, in which the mass proportion of mineral fillers in the composition is within a range from 20 to 90%, in particular from 30 to 80%.

11. A mirror according to any preceding claim, wherein the silver reflective layer is in direct contact with the glass sheet.

12. A mirror according to any preceding claim, wherein the epoxy resin-based reinforcing layer is in direct contact with the paint layer.

13. Method for obtaining a mirror according to any one of claims 1 to 12 comprising the following steps: - providing a glass sheet, - depositing at least one silver reflective layer, - depositing at least one paint layer, - depositing at least one epoxy resin-based reinforcement layer having a thickness greater than or equal to 100 pm, preferably between 100 pm and 5000 pm.

14. A method according to claim 13, wherein the step of depositing the reinforcing layer is carried out by liquid means by spraying, roller, dipping, curtain coating or sprinkling or by film pulling or by screen printing techniques.

15. A method according to claims 13 or 14, wherein the step of depositing the silver reflective layer is carried out by silver plating.