Classifications

• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C8/00—Enamels; Glazes; Fusion seal compositions being frit compositions having non-frit additions
  • C03C8/14—Glass frit mixtures having non-frit additions, e.g. opacifiers, colorants, mill-additions
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C8/00—Enamels; Glazes; Fusion seal compositions being frit compositions having non-frit additions
  • C03C8/02—Frit compositions, i.e. in a powdered or comminuted form

Definitions

• the present invention relates to the deposition of enamel on a glass substrate, in particular on a glazing. It relates in particular to a new enamel composition and a new process for the manufacture of an enameled layer on a glass substrate as well as the enameled products obtained.
• Enamels are well known in the state of the art and are used, in particular, for coating glass substrates, such as glazing, in the automotive industry or the building industry. They allow, among other things, to form inscriptions or decorative layers, conductive layers, protective layers, in particular layers of protection against ultraviolet radiation for the adhesive layers or adhesive cords intended for the mounting of glazing in bodywork bays. , masks, in particular masks for hiding collecting strips from heating networks or for hiding the adhesive cords previously mentioned, etc.
• the enamels used to coat glass substrates are generally formed (before application to the substrate and baking) of a powder comprising a glass frit (which must form the glassy matrix) and pigments (in particular as colorants, these pigments being able to also be part of the frit), the frit and the pigments being based on metal oxides, and on a medium or "Vehicle” allowing the application and temporary adhesion of the enamel to a substrate.
• the medium chosen according to the destination of the enamel, must ensure good suspension of the particles of the frits and pigments used and must be consumed at the latest when the enamel is cooked. This medium can include solvents, thinners, oils, resins, etc.
• a problem with existing enameled glass substrates is the difficulty in recycling such products, in particular in the manufacture of glass substrates in the form of sheets (glazing). Glazing having to satisfy many requirements in terms of coloring, light and / or energy transmission, etc. , it is indeed important that the glass waste reintroduced in crushed form (cullet) in the melting furnaces used for the manufacture of glazing, do not disturb the glass compositions already present usually and do not give products which do not meet the requirements required.
• enameled glass cullet If unglazed glass cullet can thus be reintroduced into a glass making furnace by floating, at rates generally of the order of 20-30% by weight of the charge of the furnace, enameled glass cullet, on the other hand , generally results in the appearance of undesirable residual colorations or unmelted residual islands in the formed glass sheets.
• the rate of enameled glass cullet that can be reintroduced in these ovens does not therefore exceed, in the most favorable cases, 2 to 3% by weight of the charge of the ovens (the enamel generally constituting 0, 1 to 0.5% by weight of this glass cullet).
• the object of the present invention is to provide an improved enamel composition and an enameling method making it possible to obtain improved enameled glass substrates (in particular glazing), in particular enameled substrates which can more easily be recycled (in particular in the glazing) that the existing enameled substrates, the enameled layers obtained also having, preferably, the characteristics usually required (in terms of opacity and coloring in particular) for the enamelled layers which must coat glazing for a motor vehicle.
• enamel composition according to the invention comprising at least one glass frit and comprising, as pigment (s), at least one or more manganese compounds, this composition further having a temperature of melting below 750 ° C.
• the enamel composition further comprises less than 10% by weight (relative to the composition) and, preferably, less than 5% by weight of silver particles .
• it comprises less than 10%, advantageously less than 5% by weight of silver particles and of any other silver-based compound and / or comprises less than 10%, advantageously less than 5% in weight of silver particles and any other conductive particle (that is to say, in the latter case, it comprises less than 10%, advantageously less than 5% of conductive particles).
• the compositions according to the invention devoid of silver particles and / or compounds based on silver and / or other conductive particles and / or certain annoying heavy metals mentioned above (in particular lead or d lead oxides), have many advantages, as explained later.
• melt composition is meant, according to the invention, the composition of the enamel considered before its firing, the enamel after firing being essentially in the form of a colored vitreous matrix.
• melting temperature of the enamel composition is meant, according to the invention, the melting temperature of the enamel in its form as deposited on the substrate to be coated. This "melting temperature” is also commonly called “cooking temperature” or “Fuse temperature”. In the enamel domain, it corresponds to the minimum temperature at which sintering is observed
• the temperature chosen for baking the enamel deposited on the substrate is then preferably chosen to be greater than or equal to its melting temperature.
• the melting temperature of the enamel composition according to the invention is less than 700 ° C.
• the enamel composition comprises at least one or more manganese compounds (it is generally a single compound but it can also be a mixture of different manganese compounds) as a pigment ( s).
• it comprises the said compound (s) of manganese as main pigment (s), that is to say that the enamel composition may optionally comprise one or more other pigments but that, in this case, the level of each other possible pigment remains lower than the level of manganese compound (s).
• the manganese compound (s) represents (s) at least 50% by weight of the pigments present, preferably at least 75% by weight of the pigments present and particularly preferably is (are) the only pigment (s) used in the composition according to the invention.
• the enamel composition according to the invention is advantageously devoid of chromium oxides, copper oxides, cobalt oxides, nickel oxides and is also devoid of other coloring compounds such as copper chromates, cobalt chromates ... and / or d other coloring oxides such as iron oxides ...
• the manganese compound (s) is (are) preferably provided in the form of manganese salt (s) and / or oxide (s) of manganese (for example Mn0 2 and / or Mn 2 0 3 and / or Mn 3 0 4 and / or MnO) to the enamel composition according to the invention, particularly preferably in the form of manganese carbonate (s) and / or Mn0 2 .
• the enamel composition According to the method of preparation of the enamel composition, it (s) can (can) also be brought (s) or be in another (s) form (s) in the composition (in particular in the form other manganese derivatives). As a general rule, it (s) give (s) one or more manganese oxides (preferably Mn 3 O 4 possibly accompanied by Mn 2 0 3 , or even MnO) at the latest when the enamel is cooked on the coated substrate.
• manganese oxides preferably Mn 3 O 4 possibly accompanied by Mn 2 0 3 , or even MnO
• the level of pigment (s) (advantageously of manganese compound (s)) in the whole sinter (s) / pigment (s) of the composition according to the invention is generally between 1 0 and 50% by weight, preferably between 15 and 40% by weight and, in a particularly preferred manner, between 20 and 35% by weight (relative to the sintered (s) / pigment (s)) assembly, in particular for reasons of opacity and holding of the enamel layer.
• the glass frit according to the invention is a vitrifiable mixture comprising oxides chosen in particular from the oxides commonly used in frits for enamel, for example chosen from oxides of silicon, zinc, bismuth, sodium, boron, lithium, potassium, calcium, aluminum, magnesium, etc.
• the glass frit is a frit comprising less than 1% (advantageously less than 0.1% and, particularly advantageously, less than 0.05%) by weight of lead oxides and, more particularly, is a frit devoid of lead oxides. It is also preferably devoid of other annoying elements such as cadmium oxides, fluorine, etc.
• it is a frit comprising Si0 2 as the forming oxide.
• it comprises Bi 2 0 3 and / or ZnO as intermediate oxide (s) (particularly preferably as main (main) intermediate oxide (s)).
• the terms "forming oxide”, “modifier oxide” and “intermediate oxide” are terms well known to those skilled in the art in the glass industry.
• the forming oxides are oxides such as silica Si0 2, B 2 0 3 ... forming the essential constituents of the glass network;
• the modifying oxides are oxides such as CaO, K 2 0, Na 2 0, BaO, etc. capable of modifying the glass network and of influencing properties such as viscosity or the melting point;
• the intermediate oxides are oxides such as Al 2 0 3 , PbO, ZnO, Bi 2 0 3 ... playing, depending on their environment and the proportion in which they are present, the role of forming oxide and / or the role of modifying oxide.
• the enamel composition according to the invention may comprise several mixed glass frits and having different characteristics (in particular melting temperatures).
• the enamel composition according to the invention comprises as sinter (s) (the pigments not being taken into account) the mixture of following components in the proportions expressed in percentages by weight (relative to this mixture): Bi 2 0 3 50-70%
• This composition makes it possible to obtain a particularly interesting enamel and exhibiting, in particular, a very good recyclability.
• the enamel composition according to the invention may also comprise a medium allowing the desired viscosity to be applied for application to the substrate and allowing bonding with the substrate.
• This medium can be any medium usually used in traditional enamel compositions and can in particular comprise solvents, diluents, oils such as pine oils and other vegetable oils, resins such as acrylic resins, petroleum fractions , film-forming materials such as cellulosic materials, etc.
• the proportion of medium in the composition ready to be deposited is preferably between 1 5 and 40% by weight of said composition.
• the enamel obtained after cooking has good opacity allowing in particular its use as a mask (for example to protect bonding cords from motor vehicles).
• the enamel is considered to have good opacity if it has an optical density at least equal to 2.8, preferably at least equal to 3.
• the optical density (OD) is measured with a densitometer, for example the GRETAG device. "D200 (in which a 550 nm filter is used) and is related to the light transmission factor T L by the relation:
• the enamel composition according to the invention is chosen so as to give, after firing, a black enamel (this is generally the case for the compositions according to the invention comprising a
• manganese salt in particular manganese carbonate and / or a manganese oxide (s) such as MnO 2 , Mn 2 O 3 and / or
• black enamel is meant subsequently an enamel having a black color after firing.
• the enamel composition according to the invention is chosen so as to obtain a black enamel having the following colorimetric coordinates, in absolute values:
• the above-mentioned color coordinates are measured in reflection, on a Minolta CM 2002 spectrocolorimeter, under illuminant D 65, for the enamel on a non-tinted glass substrate having a light transmission factor of the order of 90% and a thickness of 4 mm.
• the substrates coated with enamel according to the invention also exhibit, due to the use of the manganese compound or compounds as all or part of the pigments, a better ability to be recycled.
• the substrates coated with the enamel having the composition according to the invention are reintroduced, in the form of cullet, in a melting furnace of raw materials for the production of glass sheets (at temperatures generally of the order of 1,350 to 1,500 ° C), the color of the enamel generally disappears and does not interfere with the color of the glass resulting from the raw materials used.
• the ability to recycle the composition according to the invention as well as its opacity and color characteristics are particularly improved when the enamel composition comprises less than 10% of silver particles, or less than 10% of particles of silver and any other silver-based compound, or less than 10% of conductive particles, as indicated above, in particular when the composition is devoid of said silver particles and / or said conductive particles and / or said compounds silver-based (silver in particular which can cause problems during recycling and which can give an undesirable brown color to the enamel).
• the recyclability and / or the opacity and color characteristics of the ink and / or possibly the mechanical properties of enamelled glasses are further improved when the composition comprises less than 1% or is devoid of of one or several of the other annoying components seen previously (such as lead, chromium, copper, cobalt, nickel, iron, cadmium or the compounds, for example metal oxides, comprising at least one of these metals) .
• the enamel composition according to the invention is also easy to use and is more economical due to the use of
• manganese compound (s) these compounds being less expensive than the compounds usually used as pigments in enamel compositions. Since the pigments represent from 10 to 50% by weight of the sintered (s) / pigment (s) combination, the cost saving can be particularly significant.
• the enamel composition according to the invention can be obtained by adding in particular the manganese compound (s) (and optionally the other pigment (s)) in the form of powder (s) to a sinter powder (s) of glass, this (these) frit (s) already being suspended in a medium or not.
• the particle size of the sinter / pigment (s) assembly in powder form is preferably chosen so that at least 90% by weight of the particles forming the powder have a diameter of less than 40 ⁇ m and, particularly preferably, less than 20 ⁇ m, the choice of such a particle size making it possible to further improve the opacity of the enamel obtained after firing.
• the whole sinter (s) / pigment (s) of the composition according to the invention can also be obtained according to the following process (hereinafter called "direct process”): the mixture of suitable raw materials is fused to obtain the desired sinter / pigment (s) assembly (for example a mixture of bismuth oxide, silica, boric acid and / or borax, sodium carbonate and / or nitrate of sodium, alumina, and manganese carbonate and / or Mn0 2 , when it is sought to obtain a sintered (s) / pigment (s) set comprising the frit of composition expressed above in percentages by weight and comprising Mn0 2 as pigment) at temperatures of the order of 1000 to 1300 ° C, this melting being preferably followed by a treatment such as annealing, at temperatures below about 480-500 ° C, to obtain a structural rearrangement within the mixture (in particular within the
• the mixture is then ground to give a set of sinter / pigment (s) in the form of powder.
• the grinding carried out is a fine grinding so that at least 90% by weight of the particles forming the powder obtained have a diameter of less than 40 ⁇ m, preferably less than 20 ⁇ m and, in a particularly preferred manner, less at 10 ⁇ m (this fine grinding allowing better results in terms of opacity of the enamel).
• the powder is then optionally heat treated, generally between 400 and 600 ° C., in order to stabilize the mixture and enhance the coloration of the enamel obtained from this powder (for example giving it a "blacker" coloration).
• the direct process is particularly interesting; it is in particular simpler, faster and more economical than the traditional methods for producing enamel compositions. It generally makes it possible to obtain enamels having a blacker coloring than those obtained by mixing a powder of glass frit (s) and a powder of manganese compound (s), in particular it generally makes it possible to obtain enamels having the color coordinates previously indicated (i.e.: L * ⁇ 5; la *
• the whole frit (s) / pigment (s) of the composition is generally suspended in a medium in order to obtain a composition capable of being deposited on a substrate.
• the enameling process of the invention at least part of a glass substrate is coated with an enamel composition according to the invention, then the enameled substrate is subjected to a heat treatment so as to cook the enamel and, if necessary, so as to develop seeds of crystallization or obtain a structural rearrangement in the pigments.
• the substrate on which the enamel composition is deposited may be a bare glass substrate or a glass substrate already coated with one or more layers of enamel, preferably one or more layers of enamel according to the invention .
• This substrate may consist of one or more sheets of glass and may be toughened so as to have improved mechanical and thermal resistance properties.
• the substrate coated with enamel according to the invention thus comprises at least one glass sheet coated on at least part of one of its faces with at least one layer of enamel having a composition according to the invention.
• the enamel according to the invention can also be used to coat other types of substrates.
• the enamel composition is preferably deposited by screen printing on the substrate, then baked, the baking taking place if necessary during the heat treatment linked to the bending and / or tempering of the substrates, the firing temperatures generally being of the order of 550 to 750-800 ° C. It is observed in this connection that the enamel according to the invention can advantageously be used at 'using devices and under the temperature and pressure conditions usually used for the implementation of traditional enamels in automotive applications in particular.
• the deposition of the enamel composition can also be carried out by spraying, by coating with a curtain or with a roller, etc., the deposition being generally followed by drying, for example by infrared, to temporarily fix the enamel, for example by removing diluents from the medium used for applying the enamel to the substrate.
• each layer is preferably dried before the deposition of the next, the cooking taking place on all of the layers.
• the bending and possible tempering of the glass substrates are carried out according to known methods.
• the bending can be carried out by gravity (bending in particular of glass substrates in pairs with a view to producing laminated glasses) or using dies and, when the substrates are curved and toughened, the toughening can take place. operate after bending the enamelled substrates, possibly within the same device.
• the enamel is deposited on at least one of the substrates and the substrates are assembled and then curved, the glass substrates then being separated to insert at least an interlayer film of different material, then the laminated glazing is obtained by assembling the assembly hot and under pressure.
• enamel compositions according to the invention have anti-adhesive properties (anti-stick), these compositions not adhering to the other glass sheets or to the matrices coming into contact with them during bending operations.
• Glass substrates, in particular glazing, coated with enamel according to the invention have an improved recyclability, these substrates being generally recyclable, in particular in the form of cullet in furnaces for manufacturing glass sheets, in particular in ovens , the most widespread, for manufacturing glass sheets by floating, or "floats", at rates of up to at least 1 5%, or even at least 50% by weight of the charge of the ovens (the enamel generally constituting from 0.1 to 0.5% by weight of the glass cullet).
• the enamel-coated substrates according to the invention also have sufficient mechanical properties for their use in automotive applications.
• EXAMPLE 1 The enamel composition according to this example is carried out as follows: 100 parts by weight of a frit are mixed (in powder form) comprising 11% by weight of B 2 O 3 , 65% by weight of Bi0 3 , 1 7.4% by weight of Si0 2 , 2.6% of Na 2 0 and 4% of AI 2 0 3 , at 43 parts by weight of manganese carbonate (in powder form), then this mixture is suspended in 27 parts by weight of a medium based on pine oil comprising 3% by weight of acrylic resin, in order to obtain an enamel composition ready to be deposited on a substrate.
• composition is deposited on a glass sheet 4 mm thick and then baked between 620 and 750 ° C. approximately.
• a substrate coated with a layer of black enamel having an optical density of 3 is obtained, this substrate also being able to be hardened.
• the substrate is then ground and introduced into a raw material melting furnace for the production of glass sheets by floating, the substrate representing 50% by weight of the charge of the furnace (and the enamel representing 0.5% by weight of this substrate).
• the oven temperature is between 1,250 and 1,500 ° C. There is discolouration of the enamel and the absence of unfused after leaving the oven.
• An enamel composition is produced using 1,43 parts of a sinter / pigment set obtained by melting at about 1,200 ° C. sodium carbonate, alumina, boric acid, silica, bismuth oxide and Mn0 2 (or manganese carbonate) followed by annealing at around 450 ° C (this mixture as it is then subjected to structural rearrangement) and grinding.
• the assembly obtained has the following composition by weight: 7.7% B 2 0 3, 45.5% Bi 2 0 3, 1 2.2% Si0 2, 1, 8%
• Example 1 Na 2 0, 2.8% AI 2 O 3 and 30% MnO 2 ; this set is added to 27 parts of the medium used in Example 1, then the enamel composition thus obtained is deposited on a glass sheet and treated as in Example 1.
• the substrate is then ground and introduced into a melting furnace as in Example 1. The same results are observed as in Example 1 (that is to say a discoloration of the enamel and the absence of unfathomable products out of the oven).
• COMPARATIVE EXAMPLE The procedure is as in Example 1, replacing the manganese carbonate by a traditional pigment, copper chromate.
• the enamel obtained after cooking is black.
• After treatment between 1,250 and 1,500 ° C. of the glass cullet coated with this enamel in a melting furnace of raw materials for the production of glass sheets by floating, there is in particular a residual green coloration on the sheets of glass coming out of the oven.
• the enamel according to the present example is also more expensive (of the order of 30% more expensive) than the enamel according to example 1 and than the enamel according to example 2.
• the enamels according to the invention can in particular be used for coating glazings for the automobile industry or the building industry.

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• 1996
  • 1996-12-12 FR FR9615266A patent/FR2757150B1/fr not_active Expired - Fee Related
• 1997
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