DE102015005584A1 - Process for coating glass surfaces - Google Patents

Abstract

The invention relates to a method for coating glass surfaces, wherein a multi-layer system is applied. The invention has for its object to develop a method which makes it possible to produce mirrored surfaces in such a way that color brilliant printing can be done with colors in a multi-layer system, the mirror surface has increased protection against abrasion or scratching. In accordance with the invention, this is achieved by subjecting the glass surface on its opposite side of view (rear side) to cleaning in at least one wash cycle in a first step, applying at least one color layer / color dots in a second step, and in a third step Color layer is applied at least 1 to 3 further color layers, preferably a white UV color, • which is subjected to UV curing in a fourth step, • in a fifth step on the color layer at least 1 to 3 further color layers, preferably a white UV ink is applied, which is subjected to a UV curing in a sixth step, whereupon a silver coating is carried out in a seventh step and, after sufficient drying in an eighth step, a 1 to 3-layer protective lacquer layer is applied • in a ninth step air drying or at 120 to 18 0 degrees, preferably at 120 ° C by means of hot air or in an oven dried and / or cured.

Description

The invention relates to a method for coating glass surfaces, wherein a multi-layer system is applied.

• • Metallbeschichtungen reflektieren im sichtbaren Bereich gut (≈ 95%), versagen aber bei Silber und Gold im UV-Bereich,
• • Dichroitische dielektrische Spiegel (Interferenzspiegel) bestehen aus mehreren transparenten Schichten mit abwechselnd jeweils unterschiedlichem Brechungsindex auf einem Glassubstrat. Sie reflektieren nur in einem begrenzten Wellenlängenbereich sowie in einem begrenzten Einfallswinkel. Man kann sie so aufbauen, dass sie entweder nur in einem sehr schmalen Wellenlängenbereich sehr gut reflektieren (≈ 99,9%) oder beispielsweise den gesamten IR-Bereich durchlassen (Kaltlichtspiegel bei Halogenlampen).

Due to the type of coating of glass surfaces, one can specify the desired wavelength range with a high reflection factor:

• • Metal coatings reflect well in the visible range (≈ 95%), but fail with silver and gold in the UV range,
• • Dichroic dielectric mirrors (interference mirrors) consist of several transparent layers with alternately different refractive indices on a glass substrate. They only reflect in a limited wavelength range and in a limited angle of incidence. They can be constructed in such a way that they only reflect very well in a very narrow wavelength range (≈ 99.9%) or, for example, pass the entire IR range (cold mirror in halogen lamps).

The substrate used is also metals, plastics and even monocrystalline substances. Criteria for the choice of substrate are its machinability, thermal expansion coefficient, price and - especially at high power - the thermal conductivity. For material processing with carbon dioxide lasers, all-metal mirrors of copper are often used.

Household mirrors and mirrors on motor vehicles (exterior mirrors, headlights) consist of an aluminum layer behind glass or on plastics. For household mirrors, silver layers used to be used, but these tended to tarnish and give a slightly yellowish image.

Silver and gold layers, but also copper are well suited for infrared. The reflection in the middle and far infrared range correlates with the specific electrical conductivity of the metal used.

For ultraviolet, aluminum or dielectric layers are used.

X-rays can only be reflected at a very shallow angle to the surface (angle of incidence ≈ 90 °) of metals. Causes are the very low coherence length and the distance of the atoms, which is about the same size as wavelength. The flat impact angle reduces the apparent atomic distance.

For good imaging properties, a mirror (eg in SLR cameras, mirror galvanometers and reflector telescopes), in contrast to household mirrors, has to carry the mirror layer forward (surface mirror). In this case, the mirror layer usually has to be protected from oxidation and mechanical damage by a thin, preferably hard transparent cover layer.

As interference levels are often referred to as mirror te reflection grating. They consist of a mirror layer provided with microscopic grooves. They are used in spectrometers and monochrometers to separate individual wavelengths.

Partly permeable metal layer mirrors are based on a property that already possesses uncoated glass surfaces. They are partially reflecting in a wide wavelength range.

Such semi-transparent mirrors have on a glass sheet a reflective layer (silver, gold or other metals) that is much thinner (some 10 nm) than a normal mirror so that only part of the incident light is reflected and another part is absorbed or passes through unhindered.

Semi-transmissive mirrors are also known as "spy mirrors" or splitter mirrors and serve as beam splitters: part of the incident light is reflected, the rest is transmitted (absorption is neglected here). The respective proportions can be determined by selecting a suitable composition of the applied reflection layer.

Thin gold layers reflect primarily in the infrared, but are bluish in visible light.

Interference mirrors are always partially transparent away from their design wavelength. They carry on a glass substrate several transparent layers with alternately different refractive indices. The thickness of the layers is half the wavelength of the radiation to be reflected.

Interference mirrors reflect only in a limited wavelength range and in a limited angle of incidence, but achieve much higher reflectance (> 99.9%) than is possible with metal mirrors (up to 96%).

Interference mirrors can also be used as low-loss, partially transparent mirrors (beam splitters) and for splitting into different wavelengths or as color filters (interference filters).

Known is a coated article having a protective two-layer coating of nitride and zirconium or chromium oxide, wherein the Layer system comprises a first dielectric layer, over which a second infrared-reflective layer is disposed, over which a multilayer coating coating (silicon nitride, silicon oxide, zirconium oxide) is applied ( DE 20 2004 021 916 U1 ).

From the DE 602 20 066 T2 is a photoactive coating and a method for its preparation is known, this coating is composed of several partial layers. In advance of the coating, a vapor phase deposition is performed.

The DE 695 24 952 T2 describes an apparatus for producing electrochromic mirrors which provide a variation in light transmission for a bsplw. Use in rear-view mirrors, windows and sunroofs for motor vehicles guaranteed.

From the DE 601 26 703 T2 For example, a reflective ultraviolet wavelength multilayer system is known which is made of alternating layers of materials having different refractive indices or absorption coefficients and a protective overcoat system, the protective overcoat system comprising: carbon coated with ruthenium and silicon carbide covered with ruthenium is molybdenum carbide covered with ruthenium, alumina covered with ruthenium, titanium nitride covered with ruthenium, or titanium dioxide covered with ruthenium.

The DE 200810031889 B4 is based on the consideration that in order to ensure the desired high-quality properties of a motor vehicle mirror with particularly simple means the introduction of inhomogeneities in the mirror system or in particular in its electrically switchable electrochromic multilayer system should be consistently avoided. Such inhomogeneities in the multilayer system can be produced in particular as a result of improper or material-demanding treatment in individual steps of the manufacturing process, in particular any type of contamination such as fingerprints on the substrates during manufacture or any type of damage, for example in the form of scratches, to inhomogeneities in Multilayer system and thus can lead to impairments in the switching operation of the mirror. Furthermore, during the processing and in particular during the production of the multilayer system in the vacuum coating process, there may be shading in the region of the bearing surfaces of the individual devices during the coating of the substrate and the resulting inhomogeneities in the multilayer package.

In order to keep consistently or completely avoid these possible sources of error or interference, it is envisaged to make the actual coating on a with respect to the final application and the consequent final intended outer contour of the finished mirror actually too large mirror substrate, so that for the Intermediate handling of the not yet or only partially coated mirror substrate an outer, the actual desired contour not attributable edge region remains, where the mirror substrate in the meantime without adverse consequences for the actually intended multi-layer system touched and can be mechanically contacted for handling purposes. The shading occurring in this area in the area of the bearing surfaces during coating thus also remain without negative influence on the actually produced multilayer system in the interior of the desired contour.

The layers of the multi-layer system are advantageously applied over the entire surface in the sense that first a coating surface is coated, which extends beyond the final intended mirror contour. This coating surface can cover the entire surface of the substrate to be coated or individual use or leave blank uncoated edge areas. Advantageously, a reflector layer is applied to the mirror substrate as part of the multilayer system. The reflector layer is advantageously also applied over the entire surface, so that the coating surface goes beyond the actually intended outer contour of the mirror.

• • die Glasbeschichtungen/-verspiegelungen auf der Vorderseite der Glasfläche angebracht werden,
• • damit kein ausreichender Kratzschutz gegeben ist,
• • die Farbbrillanz der Lackierungen unzureichend entwickelt ist,
• • das Haftvermögen der Lackierungen nicht ausreichend ist,
• • vorzugsweise nur mineralische Farben verwendet werden können, was zu einem erhöhten Aufwand beim Einbrennen dieser Farben (ca. 500°C) führt,
• • keine Tiefenwirkung des Druckes erreichbar,
• • bislang keine lange Haltbarkeit, da Vergilbung, Verblassung, Oxidierung der Oberfläche.

The known state of the art has in common:

• • the glass coatings / mirrors are applied to the front of the glass surface,
• • so that there is no sufficient scratch protection,
• • the color brilliance of the coatings is insufficiently developed,
• • the adhesion of the coatings is not sufficient,
• • preferably only mineral colors can be used, which leads to an increased effort when baking these colors (about 500 ° C),
• • no depth effect of the pressure achievable,
• • so far no long shelf life, as yellowing, fading, oxidation of the surface.

The invention has for its object to develop a method which makes it possible to produce mirrored surfaces in such a way that a farbbrilliantes printing with colors in one Multilayer system can be carried out, wherein the mirror surface has an increased protection against abrasion or scratching.

• • in einem ersten Schritt einer Reinigung in mindestens einem Waschgang unterzogen wird,
• • in einem zweiten Schritt mindestens eine Farbschicht/Farbpunkte aufgetragen wird,
• • in einem dritten Schritt auf die Farbschicht mindestens 1 bis 3 weitere Farb-Schichten, bevorzugt einer weißen UV-Farbe aufgetragen wird,
• • die in einem vierten Schritt einer UV-Härtung unterzogen wird,
• • in einem fünften Schritt auf die Farbschicht mindestens 1 bis 3 weitere Farb-Schichten, bevorzugt einer weißen UV-Farbe aufgetragen wird,
• • die in einem sechsten Schritt einer UV-Härtung unterzogen wird,
• • worauf in einem siebten Schritt eine Silberbeschichtung durchgeführt und
• • nach einer ausreichenden Trocknung in einem achten Schritt eine 1 bis 3 Schichten aufweisende Schutzlackschicht aufgetragen wird, die
• • in einem neunten Schritt einer Lufttrocknung oder bei 120 bis 180 Grad, vorzugsweise bei 120°C mittels Heißluft oder in einem Ofen getrocknet und/oder gehärtet wird.

According to the invention this is achieved in that
the glass surface on its opposite side of the view (back)

• Is subjected in a first step to cleaning in at least one wash cycle,
• In a second step at least one color layer / color dots is applied,
• In a third step, at least 1 to 3 further color layers, preferably a white UV color, are applied to the color layer,
• • which undergoes UV curing in a fourth step,
• In a fifth step, at least 1 to 3 further color layers, preferably a white UV color, are applied to the color layer,
• • which undergoes UV curing in a sixth step,
• Whereupon, in a seventh step, a silver coating is carried out and
• • After sufficient drying in an eighth step, a 1 to 3-layer protective lacquer layer is applied, the
• • dried and / or cured in a ninth step of air drying or at 120 to 180 degrees, preferably at 120 ° C by means of hot air or in an oven.

The color layers are applied in such a way that a color-free edge remains in the outer region of the glass surface. The color-free edge region is preferably carried out in a width of 1 to 8 mm.

In contrast, the silver coating is preferably carried out up to the edge of the glass surface by means of silver nitrate.

The protective lacquer layer is placed around the outer edges / surfaces of the coating and the glass surface in a width of at least 0.1 mm, so that the silver layer is not achieved by air or water.

Finally, the angled outer edges of the glass surface are cleaned after the protective lacquer layer lying around of paint residues by means of preferably a ferric chloride solution, which is subsequently washed off.

As UV inks, acrylate-based inks are used. They are preferably applied with a layer thickness of 8-15 microns and then cured at 250 mJ / m ² with UV light.

Washed or pretreated with pumice (sodium aluminum silicate) to remove fats, humidity, etc. Then the pumice powder is washed off with water. In the case of stubbornly soiled panes, alcohol can also be used, but it must be washed off again to 100%, because otherwise stains will form during the subsequent mirroring (chemical reaction).

There are preferably two variants to dry the finished painted mirror. In variant 1, the mirrors are dried with the said paint in the air for at least 24 hours. In Variant 2, the mirrors are dried in a thermal process by moving them on an assembly line through an oven for 5 minutes. The temperatures are then at 120 ° C and must not exceed 150 ° C (> 150 ° C for a maximum of 1 minute). If the temperatures or holding times are exceeded, the colors and all layers (pressure, silver, paint) are gassed.

Advantages of the invention:

• • the inventive application of the coatings on the back of the glass surface (viewing surface) is a very good protection against scratching possible
• • Nevertheless, a high color brilliance is achieved, since the special structure / sequence of the individual layers or the method steps according to the invention and the use of special colors predominantly by means of UV curing a high resistance and very high radiance of the colors is achieved
• • Due to the special characteristics of the edge areas of the coated glass surface, a very durable edge protection is achieved, which also forms a very beautiful finish,
• • very high color brilliance compared to existing methods.

embodiment

The invention will be explained in more detail below using an exemplary embodiment.

Showing:

1 - The layer structure of the coating in cross section

2 - The execution of the edge region of the glass surfaces in plan view

3 - The edge area of the sealed glass surfaces in cross section

The 1 represents a cross section through the structure of the glass coating according to the invention.

On the glass surface 1 comes after the basic cleaning of the same a coat of paint 2 , which consists of a color, which by means of UV irradiation 3 is cured. As UV inks, acrylate-based inks are used. They are preferably applied with a layer thickness of 8-15 microns and then cured at 250 mJ / m ² with UV light.

After the color layer 2 will be at least one and at most three layers of a white UV color 5 applied. These two layers 2 and 3 are now cured by means of UV curing.

Then again in the step 5 printed by means of white UV ink and in step 6 again UV-cured. Re-printing with white UV ink and UV curing is essential to consolidate the colors and step through them during the later production process 7 To protect against the silver coating, since the silver nitrate to be applied consists of silver and nitric acid and thus is extremely aggressive. For the reasons mentioned, it is inventively necessary to protect the actual color printing by the described white deposits. Without these white prints, the subsequent silvering will not work as the silver nitrate damages and gnaws the colors.

Finally, the application of a protective varnish 8th in one to three layers, with a layer thickness of 40 to 60 nm, which is either air-dried or dried by means of an oven or hot air at 120 to 150 ° C (about 5 to 10 min.) And / or cured.

The border area 10 the glass surface 1 is carried out so as to leave a 1 to 8 mm wide edge, which is silver and protective lacquer coated, but has no color layers. This is the protective coating 8th around the glass edge in a width of at least 0.1 mm, so that the silver layer is not reached by air or water.

Impurities through the silver coating 7 and / or the protective varnish 8th are purified by means of preferably a ferric chloride solution, which is subsequently washed off.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 202004021916 U1 [0017]
• DE 60220066 T2 [0018]
• DE 69524952 T2 [0019]
• DE 60126703 T2 [0020]
• DE 200810031889 B4 [0021]

Claims (8)

Process for coating glass surfaces, wherein a multilayer system is applied, characterized in that the glass surface on its opposite side of the view (back) Is subjected in a first step to cleaning in at least one wash cycle, In a second step at least one color layer / color dots is applied, In a third step, at least 1 to 3 further color layers, preferably a white UV color, are applied to the color layer, • which undergoes UV curing in a fourth step, In a fifth step, at least 1 to 3 further color layers, preferably a white UV color, are applied to the color layer, • which undergoes UV curing in a sixth step, • in a seventh step, a silver coating and after sufficient drying • in an eighth step, a 1 to 3-layer protective lacquer layer is applied, the • dried and / or cured in a ninth step of air drying or at 120 to 180 degrees, preferably at 120 ° C by means of hot air or in an oven. A method according to claim 1, characterized in that the color layers are applied in such a way that a color-free edge 10 remains outside the glass surface. A method according to claim 1, characterized in that the colorless edge region 10 in a width of at least 1 to 8 mm. A method according to claim 1 to 3, characterized in that the silver coating 7 is carried out to the edge of the glass surface. A method according to claim 1 to 4, characterized in that the protective lacquer layer 8th is placed around the outer edges / surfaces of the coating and the glass surface in a width of at least 0.1 mm, so that the silver layer 7 is not reached by air or water and thus printing inks and silver are protected from external influences. A method according to claim 1 to 5, characterized in that the angled outer edges of the glass surface following the laid-over protective lacquer layer 8th be cleaned of paint residues and / or washed off. A method according to claim 6, characterized in that the cleaning of the outer edges by means of ferric chloride solution is carried out, which is finally washed off. A method according to claim 1 to 7, characterized in that the glass surface is rubbed and treated before washing by means of a pumice (sodium aluminum silicate) and then the actual wash cycle is performed.

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