WO2005014501A1

WO2005014501A1 - Substrate treated against iridescence

Info

Publication number: WO2005014501A1
Application number: PCT/FR2004/001928
Authority: WO
Inventors: Jean-François SCHMIT; Sébastien BRASY
Original assignee: Saint-Gobain Glass France
Priority date: 2003-07-25
Filing date: 2004-07-21
Publication date: 2005-02-17
Also published as: FR2857958A1; FR2857958B1

Abstract

The invention relates to a substrate, susceptible to hydrolytic attack with removal of elements, characterised in being directly covered with a layer made from an at least partially-oxidised derivatives of silicon, selected from silicon dioxide, or sub-stoichiometric oxides of silicon, the oxycarbide or the oxynitride of silicon, of a thickness sufficient to prevent all perceptible iridescence on transport and storage of a substrate in a humid, warm confined atmosphere. The invention further relates to a stack of sheets of glass, a method for storage of said stack, a method for deposition of the anti-iridescence layer on a glass substrate, a single or multiple laminated monolithic glazing product comprising said substrate and the application of the above to building, a transport vehicle, urban furniture, a cat's eye for a runway, an external lamp, a commercial window, interior furniture, a mirror, display system screen, electrocontrollable glazing or photovoltaic glazing.

Description

SUBSTRATE TREATED AGAINST IRIDESCENCE

The present invention relates to the problem of the iridescence of certain substrates which may appear in particular in a humid, hot and confined atmosphere. Under such conditions, certain substrates undergo a hydrolytic attack creating surface irregularities visible in reflection in the form of lines in the colors of the rainbow, a phenomenon called iridescence. This phenomenon is observed in a manner known to specialists following transport and storage. The hydrolytic attack particularly relates to materials containing alkalis capable of migrating to the surface; this is the case for example of the atmosphere face of the silica-calcium lime float glass, unlike the tin face (in contact with the tin bath) which is protected. In addition, the iridescence is particularly troublesome in the case of such a transparent substrate and / or for which perfect optical properties and / or flatness are required. The invention therefore aims to significantly limit or even eliminate iridescence. In the production of flat glass, the aim is to transport and store for long periods stacks of glass sheets including in a hot, humid and confined atmosphere as encountered in Southeast Asia for example. One of the secondarily obtained advantages is the possibility of increasing the volumes and reducing the frequencies of special productions as for the composition of the glass, the thickness of the sheet or on any other plane. This objective is achieved by the invention which relates to a substrate sensitive to hydrolytic attack by element exit, characterized in that it is directly covered with a layer based on an at least partially oxidized derivative of the chosen silicon among silicon dioxide or sub-stoichiometric oxides of silicon oxygen, in a thickness sufficient to eliminate any perceptible iridescence during transport and then storage of the substrate in a humid, hot and confined atmosphere. The term storage refers to a usual duration for the products concerned, in particular glazing, that is to say generally from a few weeks to a few months, rarely exceeding a period of two years, and never five years. . Within the meaning of the invention, a substrate is sensitive to hydrolytic attack by element exit when it undergoes corrosion in a humid environment due to the migration on the surface of one or more of its constituent elements. The silicon derivative may include only the elements Si, O in the case of Si0 ₂ , the elements Si, O, N in the case of an oxynitride and Si, O, C in the case of an oxycarbide. However, the silicon derivative according to the invention also comprises materials containing in addition, in a minority compared to silicon, at least one metal such as aluminum, zinc or zirconium. Adding a metal can have the following advantages: by reactive sputtering, this boosts the Si target to make it more conductive, which accelerates / facilitates deposition. In addition, whatever the mode of deposition (by pyrolysis for example), the addition of a metal of the aluminum type can increase the durability of the material, especially in the case where it is low carbon / nitrogen. Within the meaning of the invention, the silicon derivative also includes the sub-stoichiometric silicon oxides in oxygen of formula SiO _x , with x less than 2. The invention therefore applies very particularly to a glass substrate, a glass-ceramic or similar. Although essentially flat products, for which optical quality is required, are particularly targeted, the substrate of the invention can also be presented in other forms, in particular of bottle, flask, jar, fibers, tubes (in applications lighting for example) as far as these shapes can be concerned by the problem of iridescence. On the other hand in this case of a glass substrate, a glass ceramic or similar, are particularly targeted compositions containing alkalis, whether silica-calcium glass, borosilicate, vitroceramic ... Is indeed known the migration of alkalis on the surface, and the resulting reduction in the resistance of the material containing them to hydrolytic attack. In the case of float glass, in particular of the silica-calcium-lime type, it is preferably the atmosphere face, that is to say that which is not in contact with the molten tin bath, which is directly covered with the layer based on at least partially oxidized derivative of silicon. It turned out that the other side, called the tin side, was already protected from iridescence due to the hydrolytic attack. According to a characteristic of the substrate of the invention, the thickness of the layer based on an at least partially oxidized derivative of silicon is at least 1 nm, preferably at least 5 nm, an anti-iridescence effect having already been demonstrated for a value as low as the first cited, the second being such as to guarantee increased durability of the layer and its function. Larger thicknesses, in particular at least equal to 30 nm, although making it possible to achieve the object of the invention, reduce the light transmission and are, of course, more costly to produce. Other objects of the invention are: - a stack of glass sheets, at least one of which consists of a substrate according to the invention; - A method of storing such a stack of glass sheets, in particular in a humid and hot atmosphere. Indeed, the glass sheets are usually transported under variable conditions and stored in dimensions of 6 m X 3 m for example, stacked in a vertical to slightly inclined position, and separated from each other by means of dividers by blades of confined air several millimeters thick. In addition, as explained above, the invention provides the solution to a problem which arose particularly in a humid and hot atmosphere, in this case the climate of Southeast Asia. - When the substrate is made of flat glass, two types of formation of said layer based on at least partially oxidized derivative of silicon are possible, which constitutes an additional advantage of the invention: - either the formation is integrated into the float line ; - either carried out offline float, and in this case on sheets of PLF dimensions (full width float) mentioned above, or on sheets cut to the dimensions of the final product, and possibly heat treated (hardened, soaked), curved, laminated. .. if however the chosen layer formation technique - seen below in detail - allows it. Consequently, these two variants of the layer formation method constitute other objects of the invention. Preferably, this process consists of a vacuum or reduced pressure process - preferably implemented off-line float - such as sputtering, in particular assisted by magnetic field, or CVD plasma, or in a process at atmospheric pressure - implemented work on or off float line - such as by sol-gel or by pyrolysis, in particular in vapor phase (CVD thermal). On the other hand, the subject of the invention is: - a monolithic, laminated, single or multiple glazing comprising at least one substrate as described above; and - the application of such glazing to the building, to a transport vehicle in particular to a windshield, a rear window, a side window or automobile roof, to any other land, air or aquatic vehicle, to urban furniture such as bus shelters, signage or advertising, to a landing strip reflector, an outdoor lamp window or the like, to an aquarium, a display case, a greenhouse, to interior furnishings, to a mirror, a computer, television or telephone type display system screen, an electrically controllable glazing such as an electrochromic, liquid crystal, electroluminescent glazing or photovoltaic glazing. The invention is illustrated by the following example.

EXAMPLE

A layer of 7.4 nm thick silicon oxycarbide by CVD according to patent EP 518 755 from SiH4, ethylene and is deposited on a clear silica-calcium-glass of the “Planilux” type sold by Saint-Gobain Glass France. oxygen. The resistance to hydrolytic attack is evaluated both on this substrate and on a "Planilux" glass devoid of the protective layer. An accelerated hydrolytic attack is carried out by a test consisting in interposing between two 12 cm X 12 cm plates of naked "Planilux" on the one hand, of "Planilux" coated with silicon oxycarbide (coated faces) on the other hand, demineralized water in contact with the surface of the plates, sealingly isolated from a 96 ° C water bath in which the assembly is immersed by a silicone seal 3 mm in diameter, two electrodes being immersed in demineralized water and connected to a bridge for measuring electrical conductance. The appearance of iridescence corresponds to a sudden growth characteristic of electrical conductance. For bare glass, this growth appears at around 200 min, and for SiOC coated glass, beyond 1500 min. The substrate of the invention exhibits a total absence of iridescence in the actual storage conditions in countries such as India. The layer based on an at least partially oxidized derivative of silicon has excellent adhesion and mechanical properties (resistance to abrasion, to friction, etc.). It is compatible with various transformations: enamelling, heat treatment (hardening, quenching), bending, cutting (classic, with water), screen printing, edge shaping, laminating, without the optical properties (light transmission, haze) being affected. significantly affected, and without difficulty in adapting the conditions for implementing these transformations. It is thus possible, in order to benefit from the anti-iridescence functionality provided by the invention, to store bare glass coated with SiOC even under severe climatic conditions and for long periods, then to functionalize it either on PLF sheets or on sheets. cut, including by depositing additional layers or functional stacks. Finally, although the fact of covering, according to the invention, bare glass, in particular silico-soda lime with the protective layer, gives excellent results, all layers, all usual functional stacks (with thermal control function - sun protection, low emissivity) , with an optical function such as anti-reflective, filtration-coloring, electroconductive, semi-conductive, antistatic, for example) are capable of being interposed between the glass and said protective layer without departing from the scope of the invention, provided that the unit which they form with the glass is sensitive to the hydrolytic attack by exit of element.

Claims

1. Substrate sensitive to hydrolytic attack by element exit, characterized in that it is directly covered with a layer based on an at least partially oxidized derivative of silicon chosen from silicon dioxide or sub-stoichiometric oxides in silicon oxygen, silicon oxycarbide or oxynitride, in a thickness sufficient to suppress any perceptible iridescence during transport and then storage of the substrate in a humid, hot and confined atmosphere.

2. Substrate according to claim 1, characterized in that it consists of a glass substrate, a glass ceramic or the like.

3. Substrate according to claim 2, characterized in that the atmosphere side of float glass, in particular of the silica-calcium type, is directly covered with said layer.

4. Substrate according to one of the preceding claims, characterized in that the thickness of the layer is at least 1 nm, in particular at least 5 nm, and preferably at most 30 nm.

5. Stack of glass sheets, at least one of which consists of a substrate according to one of the preceding claims.

6. A method of storing a stack of glass sheets, at least one of which consists of a substrate according to one of claims 1 to 4, in particular in a hot and humid atmosphere.

7. A method of forming, on a flat glass substrate according to one of claims 1 to 4, said layer based on at least partially oxidized derivative of silicon, characterized in that it is implemented on a float line.

8. A method of forming, on a flat glass substrate according to one of claims 1 to 4, said layer based on at least partially oxidized derivative of silicon, characterized in that it is implemented off-line float.

9. The method of claim 7 or 8, consisting of a vacuum or reduced pressure process such as sputtering, in particular assisted by magnetic field- or CVD plasma, or a process at atmospheric pressure such as by sol-gel or by pyrolysis, especially in the vapor phase (thermal CVD).

10. Monolithic, laminated, single or multiple glazing comprising at least one substrate according to one of claims 1 to 4.

11. Application of glazing according to claim 10 to the building, to a transport vehicle such as a windshield, rear window, side window or automobile roof, to any other land, air or aquatic vehicle, to urban furniture such as bus shelters, traffic or advertising signs, to a landing strip reflector, an outdoor lamp window or the like, to an aquarium, a display case, a greenhouse, to interior furnishings, to a mirror, to a screen computer, television, telephone type display system, electrically controllable glazing such as electrochromic, liquid crystal, electroluminescent glazing or photovoltaic glazing.