Substrate with photocatalytic coating and process for preparing thereof
Abstract
The present invention relates to a process for obtaining a substrate (1) provided with a coating (3) exhibiting photocatalytic properties, wherein the process is characterized in that the coating includes crystallized particles (4) of an oxide of a metal A having photocatalytic properties. The crystallized particles (4) are incorporated into the coating using a mineral binder (5) comprising at least one oxide of a metal B also having photocatalytic properties in the crystallized state. The coating optionally includes at least oxide of a metal M devoid of photocatalytic properties and/or at least one silicon compound of the silicon oxide SiOi2 type. The coating (3) is deposited from liquid-phase dispersions containing the crystallized particles (4) of the oxide of metal A and at least one precursor compound for the oxide of metal B of the binder (5) and optionally a precursor compound for the oxide of metal M and for the Si compound, in a relative proportion A/(B + M + Si) by weight of the metals and Si ranging between 60/40 and 40/60. The present invention also relates to a so coated substrate and use thereof.

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31 claims: 10 independent, 21 dependent
- 1PATENTOVÉ NÁROKY 30 1. Způsob získávání substrátu (1), opatřeného alespoň na části svého povrchu povlakem (3) s fotokatalytickými vlastnostmi, kdy se krystalické částice (4) oxidu kovu A, mající fotokatalytické vlastnosti, inkorporovaly do uvedeného povlaku pomocí minerálního pojivá (5), obsahujícího alespoň jeden oxid kovu B, který má v krystalickém stavu rovněž fotokatalytické vlastnosti a případně alespoň jeden oxid kovu M, prostého fotokatalytických vlastností a/nebo alespoň 35 jedné sloučeniny křemíku Si typu oxidu křemičitého, vyznačující se tím, že povlak (3) se nanáší z disperze v kapalné fázi, která obsahuje:jednak uvedené krystalické částice (4) oxidu kovu A;jednak alespoň jednu prekurzorovou sloučeninu oxidu kovu B pojivá (5) a případně prekurzorovou sloučeninu oxidu kovu M a/nebo sloučeniny Si ve vzájemném hmotnostním poměru A/(B + 40 M + Si), vztaženém na hmotnost kovů a případně obsažených v kompozici kovu A a prekurzoru (prekurzorech) oxidu kovu B, a případně oxidu kovu M a sloučenině Si, v rozmezí od 60/40 do 40/60.
- 2Způsob podle nároku 1, vyznačující se tím, že minerální pojivo (5) je alespoň 45 částečně krystalické. -11 CZ 298629 B6
- 3Způsob podle nároku 1 nebo 2, vyznačující se tím, že jako oxidy kovu A a B jsou vybrány alespoň jeden z následujících oxidů:oxid titaničitý, oxid zinečnatý, oxid cínu a oxid wolframu, přičemž jsou výhodně oxidy kovů A i B ve formě oxidu titaničitého.
- 45 4. Způsob podle některého z předchozích nároků, vyznačující se tím, že minerální pojivo obsahuje pouze oxid kovu B, takže poměr A/(B + M + Si) se vyjádří jako A/B. 5. Způsob podle některého z předchozích nároků, vyznačující se tím, že minerální pojivo obsahuje pouze oxid kovu B typu TiO 2 a sloučeninu křemíku typu SiO 2 , takže poměr ίο A/(B + M + Si) se vyjádří jako A/(B + Si).
- 56. Způsob podle některého z předchozích nároků, vyznačující se tím, že krystalické částice (4) oxidu A ve formě částic mají výhodně střední velikost přibližně 5 nm až 80 nm a domény krystalové koherence mají střední velikost přibližně 5 nm až 20 nm, zejména v disperzi 15 v alespoň jednom organickém nebo vodném rozpouštědle.
- 67. Způsob podle některého z předchozích nároků, vyznačující se tím, že organokovová sloučenina (sloučeniny) prekurzoru oxidu B a případně oxidu M se volí ze skupiny tetraalkoxidů o vzorci M(OR) 4 , trialkoxidů o vzorci MR'(OR) 3 nebo halogenidů kovů, kde R a R'jsou 20 zbytky obsahující uhlík.
- 78. Způsob podle některého z předchozích nároků, vyznačující se tím, že organokovová prekurzorová sloučenina (sloučeniny) oxidu B a případně oxidu M jsou dispergovány v kapalné fázi obsahující alespoň jedno chelatační/stabilizační činidlo.
- 89. Způsob podle některého z předchozích nároků, vyznačující se tím, že povlak se nanáší pomocí pyrolýzy z kapalné fáze pomocí disperze obsahující organokovové sloučeniny prekurzoru (prekurzorů) a krystalické částice. 30
- 910. Způsob podle některého z předchozích nároků, vyznačující se tím, že povlak se nanáší technologií sol-gel pomocí nanášení máčením, povlékáním v kyvetě, laminámího povlékání nebo povlékání stříkáním aplikací disperze obsahující organokovovou sloučeninu (organokovové sloučeniny) a krystalické částice. 35
- 1011. Způsob podle některého z předchozích nároků, vyznačující se tím, že povlak se podrobí tepelnému zpracování zejména při teplotě alespoň 400 °C.
- 1112. Substrát (1) opatřený alespoň na části svého povrchu povlakem (3) s fotokatalytickými vlastnostmi, kde krystalické částice (4) oxidu kovu A mají fotokatalytické vlastnosti a jsou v povlaku 40 inkorporovány pomocí alespoň částečně vykrystalizovaného minerálního pojivá obsahujícího oxid kovu B, který rovněž má v krystalickém stavu fotokatalytické vlastnosti a případně alespoň jeden oxid kovu M, který nemá fotokatalytické vlastnosti, a/nebo sloučeninu křemíku typu oxidu křemičitého, zejména takového, který je získatelný způsobem podle některého z předchozích nároků, vyznačující se tím, že uvedený povlak (3) má pórovitost, vypočtenou 45 měřením indexu lomu, vyšší než 40 %, zejména mezi 45 a 65 %.
- 1213. Substrát (1) opatřený alespoň na části svého povrchu povlakem (3) s fotokatalytickými vlastnostmi, kde krystalické částice (4) oxidu kovu A mají fotokatalytické vlastnosti a jsou v povlaku inkorporovány pomocí alespoň částečně vykrystalizovaného minerálního pojivá obsahujícího 50 oxid kovu B, který rovněž má v krystalickém stavu fotokatalytické vlastnosti a případně alespoň jeden oxid kovu M, který nemá fotokatalytické vlastnosti a/nebo sloučeninu křemíku typu oxidu křemičitého, zejména takového, který je získatelný způsobem podle některého z nároků 1 až 11, vyznačující se tím, že uvedený povlak (3) má vzájemný hmotnostní poměr A/(B + M + Si), vztažený na hmotnost kovů obsažených případně v kompozici krystalických částic oxidu - 12CZ 298629 B6 A a v kompozici oxidu B, a případně oxidu kovu M a/nebo sloučeniny Si v minerálním pojivu, ve výši 60/40 a 40/60.
- 1314. Substrát (1) podle nároku 12 nebo 13, vyznačující se tím, že povlak obsahuje 5 krystalické částice o velikosti 5 až 80 nm a domény krystalové koherence o velikosti 5 až 20 nm a minerální pojivo alespoň částečně ve formě zrn, která mají zejména velikost mezi 5 a 25 nm, výhodně mezi 10 a 20 nm.
- 1415. Substrát (1) podle některého z nároků 12 až 14, vyznačující se tím, že povlak ío obsahuje krystalické částice TiO 2 v podstatě ve formě anatasu a částečně vykrystalizované minerální pojivo na bázi TiO 2 .
- 1516. Substrát (1) podle některého z nároků 12 až 14, vyznačující se tím, že povlak obsahuje částice TiO 2 v podstatě ve formě anatasu a minerální pojivo s kombinací částečně 15 vykrystalizovaného TiO 2 s SiO 2 .
- 1617. Substrát podle nároku 15 nebo 16, vyznačující se tím, že povlak má index lomu nejvýše 2, zejména mezi 1,5 a 1,9, například mezi 1,6 a 1,8. 20
- 1718. Substrát podle některého z nároků 12 až 17, vyznačující se tím, že se mezi substrát a uvedenou vrstvu s fotokatalytickými vlastnostmi vloží alespoň jedna vrstva mající funkci bariéry pro alkalické kovy a/nebo mající optickou funkci a/nebo antistatickou funkci a/nebo funkci adhezní, zejména jedna vrstva na bázi sloučeniny Si, jako je například Si, SiO 2 , SiOC, SiON a S13N4, nebo na bázi případně dopovaného oxidu kovu, jako je oxid cínu dopovaný 25 fluorem.
- 1819. Substrát podle některého z nároků 12 až 18, nebo získaný způsobem podle některého z nároků 1 až 11, vyznačující se tím, že obsahuje alespoň jeden průhledný materiál typu skla nebo plastu, zejména na součásti zasklení stínítek televizorů nebo počítačů, jako jsou 30 například dotyková stínítka.
- 1920. Substrát podle nároku 19, vy z n a č uj í c í se tím, že je součástí izolačního zasklení na vnitřních nebo vnějších stranách, zejména běžného izolačního zasklení, které má jednu plynovou mezivrstvu nebo více plynových mezivrstev, nebo „vakuového“ izolačního zasklení, nebo je 35 součástí laminovaného nebo „monolitického“ zasklení.
- 2021. Substrát podle některého z nároků 12 až 18, nebo získaný způsobem podle některého z nároků 1 až 11, vyznačující se tím, že je vyroben z kovového nebo keramického materiálu, zdicích materiálů, obkládacích materiálů nebo materiálů na střechy a podlahy, jako jsou 40 například dlaždice a tašky, kámen nebo dřevo, krytina, cement, plasty, jakýkoliv architektonický materiál, vláknitý materiál typu minerální vlny pro tepelné a/nebo akustické izolace nebo textilní vlákna.
- 2122. Disperze v kapalné fázi, obsahující:45 částice krystalického oxidu titaničitého;alespoň jednu sloučeninu prekurzoru oxidu kovu B, který má v krystalickém stavu fotokatalytické vlastnosti;případně alespoň jednu sloučeninu prekurzoru oxidu kovu M a/nebo sloučeniny křemíku, vyznačující se tím, že částice, prekurzory a sloučenina křemíku jsou ve vzájemném 50 poměru A/(B + M + Si) mezi 60/40 a 40/60.
- 2223. Disperze podle nároku 22, vyznačující se tím, že částice oxidu titaničitého jsou převážně v krystalické formě anatasu. - 13 CZ 298629 B6
- 2324. Disperze podle nároku 22 nebo 23, vyznačující se tím, že částice oxidu titaničitého mají střední velikost přibližně 5 až 80 nm a domény krystalové koherence mají střední velikosti přibližně 5 až 20 nm. 5
- 2425. Disperze podle některého z nároků 22 až 24, vyznačující se tím, že oxid kovu B se volí z oxidu titaniěitého, oxidu zinečnatého, oxidu cínu a oxidu wolframu.
- 2526. Disperze podle některého z nároků 22 až 25, vyznačující se tím, že oxid kovu M se volí z oxidu hlinitého a oxidu zirkonia.
- 2627. Disperze podle některého z nároků 22 až 26, vyznačující se tím, že prekurzorovými sloučeninami pro oxidy kovů B a M jsou organokovové sloučeniny.
- 2728. Disperze podle nároku 27, vyznačující se tím, že organokovové sloučeniny se 15 volí ze skupiny tetraalkoxidů o vzorci X(OR) 4 a trialkoxidů o vzorci XR'(OR) 3 nebo halogenidů kovů, kde RaR' představují zbytky obsahující uhlík, aX představuje M nebo B.
- 2829. Disperze podle některého z nároků 22 až 28, vyznačující se tím, že sloučenina křemíku je zvolena z alkoxidů křemíku.
- 2930. Disperze podle některého z nároků 22 až 29, vyznačující se tím, že obsahuje chelatační/stabilizační činidlo.
- 3031. Disperze podle některého z nároků 22 až 30, vyznačující se tím, že kapalná 25 fáze obsahuje rozpouštědlo, zvolené ze skupiny zahrnující vodu, ethylenglykol, ethanol, propylenglykol a jejich směsi.
- 3132. Disperze podle některého z nároků 22 až 30, vy z n a č uj í c í se tím, že obsahuje:částice krystalického oxidu titaničitého;30 tetrabutoxid titanu jako sloučeninu prekurzoru oxidu kovu B;tetraortokřemičitan jako sloučeninu křemíku ve vzájemném poměru A/(B + Si) přibližně 50/50.
Independent claims31
152 paragraphs in 14 sections, as filed
Substrate with photocatalytic coating and process for its preparation
Technical field
The invention relates to substrates provided with a photocatalytic coating, to a process for obtaining such a coating and to its various uses.
In particular, the present invention relates to coatings consisting of semiconductor materials based on metal oxide, in particular titanium dioxide, which are capable of initiating radical reactions causing oxidation of organic products under the influence of radiation at a suitable wavelength.
BACKGROUND OF THE INVENTION
Coatings of this kind make it possible to impart new functional properties to the materials they cover, in particular stain resistance, fungicidal and bactericidal properties, where these are combined, where appropriate, with hydrophilic properties, resistance to fogging, optical properties, etc.
In this context, a very wide range of substrates can be envisaged, particularly those used in the automotive or construction industry, such as glazing products, masonry, wall and floor coverings, such as tiles, tiles, slabs and tiles , and in particular any material used in construction. Thus, these materials can be made of glass, metal, glass ceramics, cement brick ceramics, wood, stone or materials reconstituted from these natural materials, plastics or mineral wool type fibrous materials, particularly useful for filtration processes, etc.
These materials may also be classified as transparent materials, particularly used for glazing, such as glass substrates or substrates made of flexible or rigid plastics, for example substrates made of polyester or acrylate, for example polymethyl methacrylate (PMMA). The substrates may also be classified in the category of non-porous or slightly porous materials (glass) or in the category of (relatively) porous materials such as tiles and ceramics.
Substrates may also be considered as "single-species" materials, such as glass substrates, or as containing an assembly or layers of materials, such as masonry, which is coated with a plaster type.
Coatings containing crystalline TiO2 anatase<sub>2</sub> having photocatalytic properties are already known from published international patent applications WO 97/10186 and WO 97/10185, where these coatings are obtained by thermal decomposition of suitable organometallic precursors and / or from "pre-crystallized" TiO particles<sub>2</sub>deposited in a mineral or organic binder.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to improve these types of coatings so that their photocatalytic efficiency is prolonged by exposure to aging conditions such as may be encountered in a variety of intended uses.
It is therefore an object of the invention to improve these types of coatings, in particular by maintaining or enhancing their photocatalytic properties while increasing their durability, in particular their mechanical or chemical durability.
In particular, the present invention provides a process for obtaining a substrate provided with at least a portion of its surface with a photocatalytic coating of crystallized metal oxide A particles having photocatalytic properties and incorporated into said coating by means of a mineral binder which
It comprises at least one metal oxide B which also has photocatalytic properties in the crystalline state. The binder may also optionally contain at least one metal oxide M which does not have photocatalytic properties and / or at least one silicon dioxide type SiO<sub>2</sub>. The method comprises depositing a coating from a single liquid phase dispersion or a plurality of such dispersions comprising:
on the one hand, said crystallized metal oxide particles A;
on the other hand, at least one precursor metal oxide compound B of a mineral binder and optionally a metal oxide precursor compound M and / or a compound of Si, in relative proportions defined by the ratio A / (B + M + Si) between 60/40 and 40/60. This ratio corresponds, on the one hand, to the weight ratios of metal A and, on the other hand, to the weight of metal B and optionally metal M and silicon Si optionally contained in the particulate oxide composition A and in the precursor composition (s)<sub>2</sub>.
The coating / treatment conditions are preferably selected such that the mineral binder, and in particular the oxide B, which is part of it, is at least partially crystallized in the final coating.
The metal oxides A and B are preferably selected from at least one of the following oxides: titanium dioxide, zinc oxide, tin oxide and tungsten oxide. One particularly preferred embodiment consists in selecting both oxides A and B in the form of titanium dioxide, whose crystalline anatase form is highly photocatalytic.
Type M oxides devoid of intrinsic photocatalytic properties are, for example, aluminum oxide and zirconium oxide.
According to the present invention, a compromise of two hitherto difficult to reconcile barriers, namely photocatalytic performance and durability of this factor, has been successfully compromised, and in particular, success in the time extension of the photocatalytic properties of the coating has been achieved. These results have been achieved because it has been shown that the catalytic effect of the coating is likely to be predominantly due to the particles introduced into it, when these particles have crystallized and are active from a catalytic point of view from the outset. Therefore, efforts have been made to maximize the amount of particles in the coating. Surprisingly, however, it has been found that both excessively high and excessively small amounts of particles are unsuitable for the purposes of achieving both of the above-mentioned desirable objectives (namely photocatalytic properties of said desirable objectives (namely photocatalytic properties and sufficient persistence of this factor). of the present invention has proven difficult to achieve in cases where wherein the amount and type of particles of oxide A are likely to affect the morphology of the B-containing binder, and wherein the change in the relatively distinctive photocatalytic nature of the coating and its temporal retention are not linear functions or do not constitute a parameter of these properties.
The process of the invention has therefore shown that it is possible to select an A / (B + M + Si) ratio in a range that allows the best compromise between a satisfactory level of photocatalytic activity and maintaining this high level of photocatalytic activity over time. The reasons for this behavior are not fully explained, at least as to the photocatalytic performance of the coating. It may be appreciated that the mineral binder also contributes to the activity of the coating. Furthermore, it should be noted that the coatings obtained tend to have excellent optical properties, in particular high light transmission and very low haze levels.
The precursors for oxide B mentioned above and optionally the precursors for oxide or oxides M are preferred organometallic compounds which are capable of decomposing to oxide by suitable treatment, in particular by heat treatment. When contaminating precursors for Si compounds, especially SiO precursor<sub>2</sub>, it is possible to use a compound from the group of silicon alkoxides (silanes).
The process according to the invention advantageously uses crystalline particles of oxide A (especially TiO)<sub>2</sub> crystallized predominantly in the form of anatase) in the form of crystallite agglomerates, preferably agglomerates with an average size of about 5 to 80 nm, and crystallites with an average size of about 5 to 20 nm
(Especially 1 to 10 nM) in a liquid phase dispersion, in particular a colloidal suspension in an aqueous medium or dispersion in at least one organic solvent. These sizes correspond to the 'diameters' of the agglomerates and crystallites concerned, bringing their shapes closer to the spheres (although this is not necessarily the case; the agglomerates in question may also be lenticular or rod-shaped).
Rather than talking about crystallite agglomerates, the correct terminology may actually be used, namely that agglomerates are particles and crystallites are what can be termed the crystalline coherence domain. In the first approximation, the same agglomerates are found in the final coating where they have undergone little or no structural or dimensional change. In fact, it has been observed that when the process for obtaining the photocatalytic coating comprises a heat treatment (similarly explained below), this treatment results in structurally altered particles with a significantly increased crystallite size. For example, in cases where TiO crystallites<sub>2</sub> initially having a size of about 5 to 10 nm, but generally about 10 to 20 nm in the final coating; their size has increased approximately twice (by a factor of 1.5 to 2.5). A detailed description of these particles can be found, for example, in the above-mentioned published international patent application WO 97/10185, or in published international patent application WO / FR97 / 02068 of 18 November 1987, published under WO 98/23549, or in FR 2 681 534.
The organometallic compound (s) as a precursor of oxide B and optionally oxide M is preferably selected from the group of tetraalkoxides of formula M (OR)<sub>4</sub>wherein M is the metal in question and R is a radical of a linear or branched carbon-containing alkyl-type group, all of which are the same or different and in particular have 1 to 6 carbon atoms. Titanium tetrabutoxide or titanium tetraisopropoxide may be mentioned in this context. It is also possible to choose these precursors from the group of trialcoxides of the MR '(OR) type<sub>3</sub>wherein R and R 'are radicals which are identical or different from the aforementioned tetraalkoxides or from the aforementioned halides, in particular titanium chlorides. Since these precursors are readily hydrolyzable and highly reactive, it is preferable to dissolve them with at least one chelating and / or stabilizing agent, for example of the β-diketone type, such as acetylacetone (2,4-pentanedione), benzoylacetone (1-phenyl-1). (3-butanedione) and diisopropylacetylacetone, or further acetic acid, diethanolamine, or glycol compounds such as ethylene glycol or tetraoctylene glycol. The concentration of the precursors in solution (e.g., for a given solids content) is adjusted by appropriate dilution with one or more organic solvents.
According to a first variant of the process according to the invention, the mineral binder of the coating contains only the metal oxide B, so that the aforementioned A / (B + M + Si) ratio is simplified to the A / B ratio.
According to a second variant of the process according to the invention, the mineral binder comprises a metal oxide B of the TiO type<sub>2</sub> and a SiO type silicon compound<sub>2</sub>so that the ratio A / (B + M + Si) becomes A / (B + Si).
The simplest method of carrying out the process of the invention is to apply a coating of the dispersion containing the precursor (s) and the dispersion containing particles that have been premixed to a single dispersion prior to spraying onto the substrate, or before the substrate is immersed in the single dispersion. a plurality of separate dispersions, in particular two dispersions, without premixing.
The first type of deposition technology is called "hot" deposition, which means that during contact of the dispersion with the substrate, the substrate is at a temperature sufficiently high to allow thermal decomposition of the precursor (s), which method represents liquid phase pyrolysis technology.
The second type of deposition technology is called "cold" deposition, which means that during contact of the dispersion with the substrate, the substrate has a room temperature or at least a temperature that is too low to cause decomposition of the precursor (s); these methods are referred to as sol-gel technology and are used in a dip coating, electrolytic coating, laminar coating or spray coating process.
In the case of the application of the "cold" deposition technique, a heat treatment is necessary after the dispersion-substrate contact phase, which must be carried out in order to confirm the coating and to ensure complete distribution of the precursors. However, this also proves advantageous in the case of "hot" technology.
Since it can improve the cohesiveness of the coating and promote at least partial crystallization of the binder, they are formed by decomposition of the precursor (s). This treatment is carried out at a temperature of at least 400 ° C, for example above 450 ° C, in particular in the temperature range of 550 ° C to 500 ° C, especially where the substrate is able to withstand this treatment, which is the case with substrates. with glass, ceramic or glass ceramic matrix.
The present invention also provides a substrate provided with at least a portion of its surface with a photocatalytic coating comprising crystalline metal oxide particles A having photocatalytic properties obtained using at least a partially crystalline mineral binder containing metal oxide B which also has photocatalytic properties in a crystalline state, in particular substrate obtained as described above. This substrate is characterized by high porosity, in particular greater than 40% and preferably between 45 and 65%. This porosity can be determined indirectly by measuring the refractive index of the layer and comparing this index to that of a completely dense material.
This indirect method represents a completely representative method of determining the porosity and morphology of the layer surface, since the refractive index measurement also takes into account at least partially the degree of unevenness of the layer surface.
(There are also other indirect methods, in particular methods of measuring the weight of the coating applied per unit area of substrate relative to a given coating thickness).
This high porosity actually has many advantages. First, it allows to reduce the refractive index of the material and change its optical appearance. In case of TiO coating<sub>2</sub> (i.e. with TiO particles<sub>2</sub> crystallized mainly as anatase and with a TiO-based binder<sub>2</sub>, optionally combined with SiO<sub>2</sub>By reducing the refractive index to a value of at most 2, in particular to about 1.4 to 1.8 and preferably to about 1.7 to 1.8, it makes it possible to greatly reduce its well-known reflection appearance.
In addition, the porosity of the coating is associated with a high surface roughness, i.e. a highly structured surface area of the coating, which increases its photocatalytic activity.
Finally, this roughness, which is probably of two different types, as described in the above-mentioned published international patent application WO 98/23459, imparts an increased and lasting hydrophilic character to the coating, thereby contributing to its pronounced anti-rain and fogging properties (water droplets flow on an invisible film) and promotes the removal of mineral impurities by removing them with rain water. Surprisingly, this high porosity does not lead to excessively high thinning of the coating from a mechanical point of view.
The present invention also provides a substrate having at least a portion of its surface coated with photocatalytic properties comprising crystallized metal oxide particles A having photocatalytic properties using at least partially crystallized binder comprising at least one metal oxide B which also has photocatalytic properties in a crystallized state, and optionally at least one photocatalytic-free metal oxide M and / or a silica-type silicon compound, in particular one obtained as described above. This substrate is characterized by a relative weight ratio of A / (B + M + Si) of between 60/40 and 40/60, calculated on the weight of the metals (and optionally Si), optionally contained in the composition of the oxide A particles and in the mineral binder oxide composition. B, and optionally M oxide and Si compound.
In this context, it should be noted that the substrate of the present invention may have a certain porosity, for example when it is a tile or fibrous appearance (for example, insulating mineral wool). In the context of the present invention, where it is stated that a substrate is provided with a photocatalytic coating, it is understood that the coating is deposited on its surface, but it can also be impregnated to a certain depth when the substrate is porous or fibrous. That is why the amount of coating exposed can be expressed by its thickness on the substrate if it is non-porous, for example if it is a glass substrate, or the amount of material per unit area, usually when the substrate has a certain porosity.
-4GB 298629 B6
The coating according to the invention, obtained either by the process described above and / or corresponding to coatings whose intrinsic characteristics have been described above, preferably has the following structure (especially when oxides A and B are both based on TiO<sub>2</sub>): crystalline particles between 5 and 80 nm in size with crystalline coherence domains between 5 and 20 nm (according to the convention described above) and a mineral binder at least partially in the form of grains that surrounds the crystalline particles in the particle gaps and have medium sizes between 5 and 25 nm, preferably between 10 and 20 nm. These "spherical" grains are not fully crystallized, although they are probably partially crystallized in a very small size, which is difficult to measure and thus "encapsulate" the particles and join them together.
According to a preferred embodiment, the substrate according to the invention is provided with a photocatalytic coating according to the invention which contains TiO particles<sub>2</sub> substantially in the form of anatase and a mineral binder comprising a combination of partially crystallized TiO<sub>2</sub> and SiO<sub>2</sub>. The coating preferably has a refractive index of at most 2, in particular between 1.5 and 1.9 or between 1.6 and 1.9 or between 1.6 and 1.8.
According to one embodiment of the invention, at least one layer is sandwiched between the substrate and the photocatalytic coating, or layers that may have different functions (optical function, barrier function to substances migrating from the substrate, e.g. alkali metals, antistatic function, adhesive layer function etc.) .)
In this context, they may be layers based on Si compounds, such as Si, SiO<sub>2</sub>, SiON, SiOC and Si<sub>3</sub>N<sub>4</sub>or based on optionally doped metal oxides (F: SnO<sub>2</sub>, Sb: SnO<sub>2</sub>, etc.).
Substrates provided with such coatings have already been mentioned in the introduction to this description. They may include transparent materials of the glass or plastic type, in particular for forming part of the glazing provided with buildings or vehicles, or screens for televisions or computers, for example screens of touch or any laminated or 'monolithic' glazing (ie containing only a single pane or single pane) plastic plate). It is also advantageous in the context of the present invention to incorporate a transparent substrate coated with the present invention into the multiple insulating glazing structure either so that the coating is situated on the inside of the glazing or on the outside of the glazing. In this case, it may be a conventional insulating glazing having one or more gas interlayers, for example of the type supplied by Saint Gobain Vitrage under the names BIVER or CLIMALIT D, CONTRETHERM, CONTRASONOR, CONTRARISC, or vacuum vacuum glazing types; wherein the gas interlayer is replaced by a vacuum, as described, for example, in European patent EP 645 516. In the latter case in particular, it is advantageous to place the coating on the outside, that is to say the side of the insulating glazing which faces outwards, in order to prevent the formation of fog by its hydrophilic nature.
The coating according to the invention is also advantageous for glazed walls of freezers. Indeed, many materials can be used as substrates for the coatings of the invention, for example, metal, ceramics, plastics or cementitious materials, and all of the above-mentioned materials used in architecture as masonry, cladding or roofing materials such as tiles and tiles. They can also be materials that are provided with interior and exterior coatings or walls of apartments, such as slabs or tiles.
It is also possible to apply this coating to mineral wool fibers for thermal and / or acoustic insulation or further to fibers of textile yarn types used as reinforcement, which fibers can be used, for example, in filtration: thus, non-soiling, bactericidal , the fungicidal and antiseptic properties of the coatings according to the invention.
The present invention also relates to a liquid phase dispersion which has been particularly described above and which can be used for the production of the photocatalytic coating according to the invention. In particular, said dispersion comprises a solvent selected from the group consisting of water, ethylene glycol, ethanol, propylene glycol, and mixtures thereof.
-5GB 298629 B6
The nature of the crystalline phase of the titanium dioxide particles in the dispersion is preferably predominantly a crystalline form of anatase. "Predominantly" means that the content of titanium dioxide anatase particles in the coating is greater than 50% by weight. The coating particles preferably have an anatase content of greater than 80%. The extent of crystallization and the nature of the crystalline phase are measured by X-ray diffraction.
The dispersions of the invention are usually obtained by mixing a dispersion of titanium dioxide particles with solutions of precursor compounds and / or silicone compounds. Depending on the nature of the compounds used, it is also possible to add additives such as solvents, surfactants or stabilizers during this mixing. Stirring can also be aided by ultrasonic mixing of the dispersion.
DETAILED DESCRIPTION OF THE INVENTION
Further details and advantageous features of the present invention will become apparent from the following description and examples, which, however, are not intended to limit the scope of the present invention in any way, with reference to the accompanying drawings.
Description of attached pictures
Figures 1 and 2 show a photocatalytic coated substrate according to the present invention, showing in each figure:
Figure 1: a simplified schematic representation of the structure of the photocatalytic coating according to the invention;
Figure 2: scanning electron microscopy (SEM) photograph of the surface of the photocatalytic coating of the invention.
A first set of examples relates to the deposition of a so-called "non-dirty" coating 3 essentially based on titanium dioxide 25 on a transparent substrate 1.
Substrate I is made of clear flat soda-lime silica glass with an area of 15 x 40 cm<sup>2</sup> and a thickness of 4 mm. It goes without saying that the invention is not limited to this specific type of glass. In addition, the glass need not be flat, but may be curved.
Optionally, between the coating 3 and the substrate 1 there may be a silicon oxycarbide thin film 2 of the formula SiOC to form an alkali metal diffusion barrier that is deleterious to the photocatalytic properties of the coating, and / or an optical-functional layer, e.g. vapor deposition (CVD), about 50 nm thick.
Examples 1 to 7
In this context, two different "cold" deposition processes have been used, namely, dip coating in a cuvette at a bath flow rate of about 5 to 30 cm / minute and spraying, i.e. spraying a cold liquid. These well known technologies are explained in detail in the patent applications cited above.
The coatings are deposited from the dispersion obtained by mixing two starting solutions / dispersions 1 and 2:
solution 1: a solution containing the organometallic precursor of TiO2-based mineral binder. It is titanium isopropylate Ti (OCH (CH<sub>3</sub>)<sub>2</sub>14, stabilized with acetylacetonate CH<sub>3</sub>-CO-CH<sub>2</sub>-CO-CH<sub>3</sub> in ethanol;
Dispersion 2: ethylene glycol liquid phase containing photocatalytic crystalline particles having the following characteristics:
particle specific surface area:> 350 m<sup>2</sup>/ g, particle size «40 nm,
The size of the crystallites which form 7 nm particles, crystalline phase: more than 80% of anatase.
The dispersion composition obtained by mixing solution 1 with dispersion 2 is adjusted to obtain 5 the desired Ti ratio<sub>(1</sub>/ Ti (2), i.e. the ratio of the weight of the titanium (2) coming from the particles in dispersion 2 to the weight of the titanium (1) coming from the precursor in solution 1 (usually this ratio may be from a metal precursor, provided that 100% of the precursor is converted to an oxide, resulting in the same result).
Examples 1 to 7 relate to cuvette deposition from comparable deposition conditions, i.e., at the same bath runoff rate (6 cm / min) and at the same titanium concentration (i.e. a solids content of 3%, calculated on the weight of oxide) originating from the precursor in solution 1.
After application, the substrates are heat treated at about 450-500 ° C for at least 30 minutes.
Table 1 below gives, for each example: the ratio of Ti (i / Ti (2) explained above, dimensionless value; coating thickness (e) 3 in nm;
the light transmittance value T<sub>L</sub> in%, measured by light source D<sub>6</sub>with;
a turbidity value, expressed as a percentage, expressed as the ratio of diffuse transmittance to light transmittance, integrated overall in the visible area.
TABLE 1
<td>Example</td><td><sup>Ti</sup>(l) /<sup>Ti</sup>(2)</td><td>e (ran)</td><td>T<sub>L</sub> (%)</td><td>Turbidity (%)</td>
<td> 1</td><td>O / 100</td><td> 20</td><td> 88,5</td><td> 0,88</td>
<td> 2</td><td> 20/80</td><td> 20-30</td><td> 89,6</td><td> 0,27</td>
<td> 3</td><td> 40/60</td><td> 40-50</td><td> 89,5</td><td> 0,76</td>
<td> 4</td><td> 50/50</td><td> 40-60</td><td> 90,2</td><td> 0,50</td>
<td> 5</td><td> 60/40</td><td> 60</td><td> 90,5</td><td> 0,61</td>
<td> 6</td><td> 80/20</td><td> 30-40</td><td> 89,7</td><td> 0,44</td>
<td> 7</td><td> 100/0</td><td> 30-40</td><td> 90,3</td><td> 1</td>
Example 8
The sample of Example 8 was made from a dispersion as in Example 4, but applied to the substrate by cold spraying using a so-called airless spray nozzle with a pressure of 0.07 grams (0.7 MPa).
The obtained layer after heat treatment at a temperature of about 450 to 500 ° C for at least 30 minutes had a thickness of about 35 to 60 nm, a T value<sub>L</sub> 88.6% and a haze value of 0.6% under the same conditions as in Table 1.
The above examples 1 to 8 were evaluated for photocatalytic activity before and after treatment aimed at simulating accelerated coating aging.
Photocatalytic activity was measured as follows:
1. the test was performed at approximately 15 cm<sup>2</sup> coating;
2. the sample was weighed and the substrate thickness, T<sub>L</sub> and turbidity;
-7EN 298629 B6
3. a solution of palmitic acid (8 grams of acid per liter of chloroform) was sprayed at a nozzle-to-glass distance of 20 centimeters at a vertical position of the substrate in 3 to 4 successive procedures;
4. after deposition of palmitic acid, the sample was weighed to determine the thickness of the deposition acid in nm;
5. turbidity was measured after application and T<sub>L</sub>;
6. Measurement of turbidity change as a function of UV radiation time (= 30 V / m<sup>2</sup>);
7. graphical determination of the time after which the turbidity decreased by 50%: this time is called T<sub>1/2</sub> (disappearance);
8. evaluation of the photocatalytic activity of the coating as the rate of disappearance of this activity in (unit 10 nm / h), defined as follows:
v (nm / h) = [palmitic acid thickness (nm)] / [2 x ti<sub>/2</sub> (disappearance).
The aging of the coating was performed by subjecting the coating to mechanical abrasion as follows:
sample size: 7 cm χ 15 cm;
applied load: 600 g;
Abrasive felt area: 1.5 cm<sup>2</sup>;
n cycles (1 cycle = 1 forward and backward movement of the felt support arm and load) at n = 200 and 500.
Table 2 below shows for each example:
disappearance rate vl before abrasion;
disappearance rate v2 after 200 cycles; disappearance rate v3 after 500 cycles.
TABLE 2
<td>Example</td><td>pr.n. (0 cycles)</td><td>v2 (200 cycles)</td><td>v3 (500 cycles)</td>
<td> 1</td><td> 20</td><td> 10</td><td> 0</td>
<td> 2</td><td> 40</td><td> 5-10</td><td> 0</td>
<td> 3</td><td> 35</td><td> -</td><td> -10</td>
<td> 4</td><td> 70</td><td> 10-20</td><td> -10</td>
<td> 5</td><td> 35</td><td> -</td><td> -5</td>
<td> 6</td><td> 20</td><td> 1-2</td><td> 0</td>
<td> 7</td><td> 20</td><td> 0</td><td> 0</td>
<td> 8</td><td> 40</td><td> -</td><td> 7</td>
However, analyzes have shown that the coatings in Examples 3, 4 and 5 have a structure likely to be close to that shown in a very simplified manner in Figure 1, which represents a glass substrate 1, a SiOC 2 layer and a coating 3. This coating contains particles or aggregates of crystallites 5 agglomerates of amorphous or slightly crystallized TiO grains<sub>2</sub> 4, which form the mineral binder of the coating.
-8EN 298629 B6
Figure 2, more precisely corresponding to Example 4, is a photograph obtained by scanning electron microscopy and provides information on the surface appearance of Example 4: a very rough surface allowing the coating to provide a highly structured surface area.
It should be noted that the sample of Example 4 has a refractive index of about 1.65. Knowing the refractive index of “basic” TiO<sub>2</sub> 2.4, it can be assumed in the first approximation that the porosity of the coating is approximately (2.4-1.65) / (2.4-1), i.e. approximately 54%. The coating of Example 4 also exhibits strong hydrophilicity. After exposure to UV radiation for 20 minutes to activate, the sample is stored in the dark and the contact angle Φ relative to water is measured periodically: this contact angle remains less than 10 ° for at least 20 days in the dark.
The following conclusions can be drawn from these data: in examples 3, 4, 6 and 8, and in particular in example 5, in which the ratio Ti (2>: Ti (i) 50/50), all the desired properties are combined, namely: high T<sub>L</sub>, low haze and refractive index less than 2 give the coating a very favorable optical appearance;
satisfactory photocatalytic activity, which remains even after mechanical stress, which proves the durability of the coating and makes it possible to use these coatings under real conditions, for example for external glazing, because they have an acceptable "durability". It is in fact the only example produced that still exhibits photocatalytic activity after 500 cycles of abrasion, albeit moderately.
Examples 9 to 13
The second series of examples relates to the same type of coating based on the same "solution 1" and the same "dispersion 2". The deposition conditions are the same as above for Examples 1 to 7, except that the bath drip rate is now higher and is equal to 24 cm / min. Another difference concerns the substrate: in these examples, the same glass is pre-coated with a first 50 nm SiOC layer coated with CVD and then a second 450 nm layer of fluorine F: SnO doped tin oxide<sub>2</sub>applied by a known method of powder pyrolysis. Further, in this set of examples, the amount Q of the photocatalytic coating is not measured by measuring its thickness, but by measuring the amount of material per unit area of the substrate, expressed in pg / cm.<sup>2</sup>.
The photocatalytic activity of the examples is measured prior to the abrasion test, i.e. the value of ll explained above. The durability of the coating is assessed qualitatively simply by wiping with a cloth: "++" means that the coating is very strong, "+" means that it is still suitably resistant means that the coating is (almost) removed by wiping with a cloth.
Table 3 below shows, for Examples 9 to 13, the Tip / Ti ratio) with the same meaning as in Table 1, the Q value, the vl value and the rag wipe evaluation:
TABLE 3
<td>Example</td><td><sup>Ti</sup>(2)/<sup>Those</sup>(and)</td><td>Q (pg / cm<sup>2</sup>)</td><td>ll (nm / h)</td><td>Evaluation wiping</td>
<td> 9</td><td> 0/100</td><td> 22</td><td> 18</td><td> ++</td>
<td> 10</td><td> 20/80</td><td> 24</td><td> 128</td><td> +</td>
<td> 11</td><td> 40/60</td><td> 23</td><td> 159</td><td> +·</td>
<td> 12</td><td> 50/50</td><td> 25</td><td> 231</td><td> +</td>
<td> 13</td><td> 100/0</td><td> 23</td><td> 222</td><td> -</td>
-9EN 298629 B6
This table shows the same tendency as in the first series of experiments related to the same or almost the same amount of coating applied. Optimum occurs in Examples 11 and 12 with Ti ratios<sub>(2</sub>) / Ti (i) 40/60 and 50/50. Only Example 12 exhibits a photocatalytic activity above 200 and a good durability.
Examples 14 to 16
A third series of examples relates to coatings with TiO particles<sub>2</sub> in the dispersion used in all the previous examples, but with a hybrid binder with a combination of TiO<sub>2</sub> and SiO<sub>2</sub>.
In a solution containing binder precursors:
as solvent: ethanol and ethylene glycol in a 75/25 weight ratio; as stabilizer: acetylacetonate;
as a TiO precursor<sub>2</sub>titanium tetrabutoxide (TBT);
as a SiO precursor<sub>2</sub>: tetraethyl orthosilicate (TEOS).
The relative proportion of TBT and TEOS is adjusted so that the Ti weight ratio is in solution<sub>2</sub>O / SiO<sub>2</sub> of 15/85 (assuming that all TBT has been converted to TiO<sub>2</sub> and all TEOS on SiO<sub>2</sub>).
Then this solution was added to the particle dispersion used in the previous examples in such proportions as to obtain the desired ratio r Ti (particles) / (Ti<sub>precursor</sub> + Si<sub>prekurzO</sub>(r) - (The solids content of this solution is 3%.)
The deposition and substrate conditions are identical to those in Examples 9 to 13.
Table 4 below gives the values of the ratio r explained above, the values of the velocity explained above, the light reflection on the coated substrate R<sub>L</sub> % and changes in T<sub>L</sub> (delta T<sub>L</sub>), obtained after 500 cycles of the abrasion abrasion test described in connection with the first series of examples, as well as the ratio η, which expresses the ratio of the amount of Ti to the amount of Si as the weight of the oxide.
η TiO<sub>2</sub>particles / (TiO<sub>2p</sub>drawbar<sub>vo</sub> E SiO<sub>2</sub>p<sub>O</sub>jj<sub>vo</sub>)
The table also shows the amount of total TiO<sub>2</sub> in Qi coating (particles and TiO<sub>2</sub> from titanium precursor 35) in pg / cm<sup>2</sup> and the calculated amount of coating as the total weight Q<sub>2</sub> also in pg / cm<sup>2</sup>.
TABLE 4
<td>Example</td><td>Γ</td><td><sup>r</sup>l</td><td>pr.n.</td><td><sup>r</sup>l</td><td>delta Ίγ</td><td><sup>Q</sup>and</td><td>q<sub>2</sub></td>
<td> 14</td><td> 45,1/54,9</td><td> 40/60</td><td> 8</td><td> 42,5</td><td> 0</td><td> 8,8</td><td> 18,2</td>
<td> 15</td><td> 55,3/44,7</td><td> 50/50</td><td> 40</td><td> 10</td><td> 1</td><td> 9,3</td><td> 16,3</td>
<td> 16</td><td> 65/35</td><td> 60/40</td><td> 45</td><td> 14</td><td> 4</td><td> 10,1</td><td> 15,4</td>
The deposition was repeated to adjust the solids content of the solution and the drip rate, with the ratio r being determined to be 55.3 / 44.7 and the amount of coating applied was varied.
Table 5 below shows the amount of Q in pg / cm 2 for these additional experiments to experiment 6<sup>2</sup>, the corresponding thickness in nm (if measured), the value in l (in nm / h), the value of R<sub>L</sub> and a delta T value<sub>L</sub>as explained above:
-10GB 298629 B6
TABLE 5
<td>Example</td><td>Q</td><td>E</td><td>pr.n.</td><td><sup>r</sup>l</td><td>delta</td>
<td>15a</td><td> 17</td><td> 110</td><td> 42</td><td> 8,5</td><td> 1,5</td>
<td>15b</td><td> 33</td><td> -</td><td> 88</td><td> 12,1</td><td> 2,5</td>
<td>15c</td><td> 49</td><td> 460</td><td> 130</td><td> 11</td><td> 0,8</td>
From this third series of experiments it is apparent that it is preferable to add SiO material<sub>2</sub> to the binder, whereby this material is not involved in photocatalysis, but allows a more homogeneous coating and increases its durability. It is also apparent that, although the ratio r is key, other parameters may also act, in particular a Q value which is preferably in the range between 15 and 45 pg / cm.<sub>2</sub>to take into account the cost of the coating and the impact of its thickness on the optical appearance.
It is understood that the invention is not limited to these specific examples. In particular, it is within the scope of the invention to further enhance the photocatalytic activity of particles 5 by doping them by introducing a dopant into the crystal lattice, or by coating the particles with said dopant from the group comprising Fe, Cu, Ru, Mo, Bi, Ta, Nb, Co, Ni, etc. as described in the above-mentioned International Patent Application WO 97/10185.
It may also be within the scope of the invention to add a mineral binder containing oxides that are not photocatalytic in the crystalline state or are only slightly photocatalytic, for example by adding precursors to other SiO-type oxides<sub>2</sub>, such as tetraethoxysilane, into a dispersion.
The aforementioned A / (B + M + Si) ratio, which is optimal in the range of 40/60 to 60/40, may range between 35/65 to 40/60 and 65/35 and 60/40 in the lower claims.
Contents14
2 sheets
Sheet 1 Sheet 2
Every citation, both ways
| Document | Relation | Office | Cited during |
|---|---|---|---|
| WO9600198A1 | Cites | World Intellectual Property Organization (WIPO) | Search report |
| WO9710185A1 | Cites | World Intellectual Property Organization (WIPO) | Search report |
| WO9710186A1 | Cites | World Intellectual Property Organization (WIPO) | Search report |
30 members in 15 offices
Priority claims1
| Document | Office | Kind | Date |
|---|---|---|---|
| 9802676 | France | A |
Members30
| Document | Office | Kind | |
|---|---|---|---|
| FR2775696A1 | France | A1 | |
| WO9944954A1 | World Intellectual Property Organization (WIPO) | A1 | |
| AU3258899A | Australia | A | |
| FR2775696B1 | France | B1 | |
| TR2000002575T2 | Türkiye | T2 | |
| TR200002575T2 | Türkiye | T2 | |
| BR9908509A | Brazil | A | |
| EP1087916A1 | European Patent Office (EPO) | A1 | |
| KR20010041601A | Republic of Korea | A | |
| CZ20003244A3 | Czechia | A3 | |
| PL342761A1 | Poland | A1 | |
| JP2002505349A | Japan | A | |
| HU0102680A2 | Hungary | A2 | |
| HUP0102680A1 | Hungary | A1 | |
| US6465088B1 | United States of America | B1 | |
| HU0102680A3 | Hungary | A3 | |
| HUP0102680A3 | Hungary | A3 | |
| US2003082367A1 | United States of America | A1 | |
| US6720066B2 | United States of America | B2 | |
| EP1087916B1 | European Patent Office (EPO) | B1 | |
| AT323062T | Austria | T | |
| ATE323062T1 | Austria | T1 | |
| KR100574327B1 | Republic of Korea | B1 | |
| DE69930851D1 | Germany | D1 | |
| DE69930851T2 | Germany | T2 | |
| ES2262332T3 | Spain | T3 | |
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| CZ298629B6This record | Czechia | B6 | |
| JP4911376B2 | Japan | B2 | |
| HU228133B1 | Hungary | B1 |
1 legal event, as the office reported them to INPADOC
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Numbers
- Application
- 20003244
Titles2
- Czech
- Substrát s fotokatalytickým povlakem a zpusob jeho prípravy
- English
- Substrate with photocatalytic coating and process for preparing thereof
Classification
- CPC, 30
- C04B41/5041
- C03C17/007
- C03C17/256
- C03C2217/212
- C03C2217/45
- C03C2217/475
- C03C2217/477
- C03C2217/71
- C03C2218/113
- C09D1/00
- C23C30/00
- H01J29/88
- Y10T428/259
- Y10T428/12667
- Y10T428/1266
- Y10T428/256
- Y10T428/249988
- Y10T428/249953
- Y10T428/249987
- Y10T428/249956
- Y10T428/24999
- Y10T428/24997
- Y10T428/249967
- B01J35/30
- B01J35/39
- B01J2235/30
- B01J35/38
- B01J35/77
- B01J35/70
- B01J2235/15
- IPC, 16
- B32B9 00
- C03C17 25
- C03C25 1065
- B01J35 30
- B01J35 38
- B01J35 70
- B01J35 77
- C03C17 00
- C03C25 42
- C03C27 06
- C04B41 50
- C09D1 00
- C09D5 00
- C23C30 00
- G06F3 041
- H01J29 88