WO2009121312A1

WO2009121312A1 - Coating and/ or building material intended for object and building treatment with photo-catalytic and self-cleaning effect

Info

Publication number: WO2009121312A1
Application number: PCT/CZ2009/000045
Authority: WO
Inventors: Petr Ratajsky
Original assignee: Rokospol A.S.
Priority date: 2008-04-03
Filing date: 2009-04-01
Publication date: 2009-10-08
Also published as: CZ2008209A3

Abstract

The coating and/or building material comprises at least one compound from the group consisting of oxides and metal salts in nanocrystalline form with photocatalytic activity especially in the visible region of the solar spectrum, which is anchored to the respective material on the base of a geopolymer or geopolymers.

Description

COATING AND/OR BUILDING MATERIAL INTENDED FOR OBJECT AND BUILDING TREATMENT WITH PHOTO-CATALYTIC AND SELF-CLEANING EFFECT

Field of the invention

The inventions is related ;to a coating and/or building material to treat objects and buildings containing; an active catalytic component for photodegradation of selected pollutants in the air and a binding agent based on geopolymers.

State of the art

At present, a number of agents is already known used as building and coating materials (particularly for outdoor buildings and structures) featuring effects of photodegradation on air pollutants.

As regards building materials, e.g. cement compositions containing photocatalytically active titanium dioxide as an admixture are known..

As regards the recipes of coating compounds for surface treatment of outdoor buildings and structures, the application of organo-metallic precursors containing particles of photocatalytically-active compounds proves useful — in particular the application of titanium dioxide. In this respect, for example the application of precursors produced by homogenous hydrolysis of soluble salts (chlorides) of titanium by urea or thiacetamide in aqueous medium is known. However, the obtained precursors may only be used as an active component of the respective coating compound — and not directly as a coating material itself. It is therefore more promising to use transparent layers on the base of polyvinyl alcohol or hydroxyethyl acrylate - precursors produced by the hydrolysis of soluble titanium salts in the presence of the respective polymers. Nevertheless, even these precursors are not able to ensure by themselves the necessary mechanical and chemical resistance of an outdoor coating. Besides, conventional technologies of surface treatment and construction work are known. They are based on the use of mineral coats, jointing compounds, heat-retardant and facing coatings and other solid and thin-layer coatings and structures made from geopolymers. The benefit of these materials - in contrast to the above quoted construction and coating compounds with the effects of photodegradation on the air pollutants - is primarily the fire resistance and the resistance to an aggressive medium. At present, the known surface treatments on the base of geopolymers are exclusively based on the passive treatment of building surfaces. In this aspect no solution has been hitherto known that would have an active positive influence on the reduction of ,

an4 volatile matters originated ^y..hμman a.ctiyitiesXas cleaning effect_{. (}

Summary- of the invention ,

.Ttϊe,,cp.ating compound and/or building material to treat the objects and buildings, featuring phptpcataly tip, an4 s.elf-cjeariirig effect according. to this inyeintion cpntri_jbut.es to, the elimination, of tlie abpyprmentionep!.βhprtcpm,ings of the, hitherto state ,of art. The gist of the inyentioij consists in the fact that this

The compound from the group of oxides and metal salts in nanocrystalline form with photocatalytic activity may also be contained in the transparent coat on the geopolymer surface.

The preferred geopolymer_. is the geopolymer on the base of natural alumosilicate or a waste raw material from the group containing blast furnace slag - clinker, shale and metakaolin.

A compound with photocatalytic activity from the group consisting of oxides and metal salts may be preferably titanium dioxide doped with oxides of transient metals, particularly Fe, Co, Ni, Mn, Cr, V, Ta, Nb, W and/or lathanoid oxides,, particularly La, Ce, T>Td, Y, Sm, Eu, Dy, which has the form of mostly, spherical, particles with lattice perturbances induced by dopants and it is photoactive under visible light.

Λijpther. variant of the compounds with photocatalytic , actiy ity, from the grour^ consisting of oxides an4.mςtal s^lts are mixed oxides of the type of, TiQxMeQ .on. the base of titanium dioxide doped with oxides of transient metals MeO, in which. the Me metal is particularly Fe, Co, Ni₅ Mn, ,.Cr₅ Y, Ta,_; Nh, W an,d/oi: tjhe lathanoid, oxides, in particular La, Ce, Nd, Y, Sin, Eu, Dy. A, compound with photocatalytic activity from the group consisting.of , oxides an,d..metal, salts can also:b^ created from the resulting productof , hom.Qge,riep.us hydrolysis, of TiCl₃, TiCl₄, or TiOSQ₄ by urea in .aqueous, medium..;. It m^.y also, be the titanium oxide in the form of transparent particles, which is the. product of hydrolysis OfTiCl₃ or TiCl₄ in. the. medium of polar . polymers,, as hydroxyethyl metaacrylate or inorganic polymers on the. base of silicates, esters ,of silicic acid, siloxanes or silicon alkyloxides.

The practical gain of the new coating and building materials according to the present invention results from: the combination of the gains of the compounds with photocatalytic activity and the materials on the base of geopolymers. It consists primarily in the possibility of obtaining long-term cleanliness of surface, preservation of porosity and permeability of surface and also in the fact that while maintaining long-term service life of the surface, the particles of compounds with photocatalytic activity can act on the degradation of pollutants in the environment. In the interior, there exists a possibility of degradation of organic and inorganic air contaminants and thus of maintaining the interior environment clean from the ecological point of view.

This effect can also manifest itself in the application of outdoor surfaces of buildings, as most emissions are mainly formed in densely built up and densely populated agglomerations with the greatest number of areas suitable for the treatment with, these materials. It also offers the advantage consisting in the fact that the photodegradation can also take place on the surfaces in shadow - due to the diffused light, though the effectiveness will be probably somewhat lower.. The polluted air renewal may be ensured by the heated air flowing along the walls on the sunlight side of the buildings and, at the same time,. by the action of wind flows. On the shadow side, only the second method is cogitable. At the same time, the method of the application of the material is also of importance, so that the declared properties could manifest themselves as much as possible. Extremely important is the open surface structure ensuring sufficient diffusion of air into the, structure of the photocatalytically active material.

. • „ . The building materials according to the present invention may also include the high-build materials, as for example jointing compounds.

Examples of embodiments of the invention

Example 1

..The. coating compound for a thin-layer coating on the base of . geopolymers containing nanocrystalline titanium dioxide is prepared in. the exemplary embodiment from the following components: 200 to 500 parts by mass of metakaolin or shale is mixed with 20 to 250 parts by mass of standard white pigment (zinc white, titanium white, vel sim.) and with 100 to 500 parts by mass of blast furnace slag (clinker). Add 0.1 to 50 parts by mass of powdered nanocrystalline titanium dioxide, photoactive under visible light region (KFD embodiment) to the obtained homogeneous mixture Stir the mixture shortly and add 100 to 500 parts by mass of solid sodium water-glass or potassium water- glass and stir it up. Then add 100 up to 500 parts by mass of water. The obtained compound may be filled up with thickener, antifoaming agent,,_. spreading, g,gent etc.,

also with, the polymeric dispersion of organic, or inorganic type in the .amoμnt of up, to 20% per dry, matter, _{r .} This, coating, applied with a brμsh, a rolle,r or b,y. spraying,, after, the contained water-glass has been allowed to >dry_. and mature thoroughly (neutralizing_.it with , atinospheriq carbon dioxide),, will form a well permeable,. lpns-life,, weather- re.sjstant.sμr_^faQe layer, with a.longrterm phptocatalytic effect reducing the content of emission gases from, ;the epvironment,and highly resistant to. prganjic ^.nd inorganip pollution (fungi^ mpulds, bacteria, ., dust, etc).

Example.2

percent, by wpight of dry. powder ;nanocrystall.ine titanium dioxide_? phptpaqtiye, uηder..vi3ible, light region (KFp)^Ihis compound is then used to perform the final treatment (overpainting) in the thickness of the dry film of 0.5 up to 30 μm, depending on the smopthness pf the building surface. The. created layer is sufficiently cpmpact; to ensure its resistance tp water and its moderate thickness, so that in the course of drying it could form a partially permeable film to gases and steam. The other physical - mechanical parameters of the surface treatment (adhesion to the base, colour tone, colour tone stability etc.) remain unchanged.

It is preferable to use polymeric coatings on the base of hydroxylated derivates of poly aery lie acid as a binder for the preparation of the specified transparent base. They can be well combined with photoactive nanocrystalline titanium oxide to ensure a high permeability to gases and, at the same time, high hydrophility necessary to enable the creation of the so-called "self-cleaning ability",,_,,

The transparent phptocatalytic coatings may., also be on ^tlΛ _.e base of inorgan,ic_.p.plymers. from, silicates, silicic esters,, siloxanes or silicon alkyloxicles.

Example 3. ,

. _... ₄. Jp acings. containing, nanocrystalline titanium oxide, are analogous, tp. facing and Interior, or other thin-laypr. cpatings. ^■

Example, 4

T^e ,φin,₇layer_;coatirig; on ,the_f.base..of geopolymers. containmg ,, nanocrystalline titanium dioxide is prepared from 200 up to 500 parts by mass of metakaolin or shale, which is surface treated with composite homogeneous coagulation by urea in aqueous medium. Using this method, all the foregoing examplea.of powder compounds_. phptoactiye in, the region of , visible, light, (KDF.) cari:be_jpr,e_.ςipitated. direct on the. surface of a component of the geopolymers. It is preferable to use a spathic filler and substances in the composition of the geopolymer, or o part of them, which can (but need not) participate in an active way ,^n. tlie_. reaction, as for example clinker, shale, metakaolin etc., or possibly non-active fillers. The selected filler (active component) is fed direct into the reactor prior to initiating the homogenous analysis. Thereafter the product is mixed with 20 to 250 parts by mass of standard white pigment (zinc white, titanium white, vel sim.) and 100 to 500 parts by mass of blast furnace slag (clinker). Add 0 to 50 parts by mass of powdered nanocrystalline titanium dioxide, photoactive in the regfdri of visible light (KFD embodiment) to the obtained homogeneous mixture; Stir the mixture shortly and add 100 to 500 parts by mass of solid sodium water-glass or potassium water-glass and stir it up. Then add 100 up to 500 parts' by mass of water. The obtained compound may be.fϊlled up with thickenerr, ^ntifpaming agent, spreading agent etc., and possibly._.also, with polymeric dispersion of organic.or-inorganic.type.iriithe; _iV amount. o,f|up^

Example, 5,-. ₍

_. •; _t .. In a^manner- analogous ..tq^at of Example 4, applying the method Of₁. homogenous,, precipitation by urea^a. layer, photoactive, in the. region .of yisibje light (KDP¹) can be created. .

Example 0

In a manner analogous to that of the coating compounds for thin-layer ^' coatings -^ see^' Example^ 1 — it is also possible to prepare high-build compounds, for example jointing compounds.

Claims

P A T EN T C L A I M S

1. Coating and/or building material to treat objects and buildings with photocatalytic and self-cleaning effect, in particular with catalytic effects on photodegradation of pollutants in the air, wherein it comprises at least one compound from the group of oxides and metal salts in nanocrystalline form with photocatalytic activity especially in the visible region of solar spectrum, which is anchored to the respective material on the base of geopolymer or geopolymers.

2. Coating and/or building material according to claim 1, wherein the compound with photocatalytic activity is suspended in the geopolymer in the form of suspension

3. Coating and/or building material according to claim 1, wherein the compound with photocatalytic activity creates a coating on a component of the geopolymer or of a component part of it.

4. Coating and/or building material according to claim 3, wherein the compound with photocatalytic activity creates a coating on the spathic filler of the geopolymer or. on a component part of it.

5. Coating and/or building material according to clam 1, wherein the compound with photocatalytic activity is contained in the transparent coat on the geopolymer surface,

6. Coating and/or building material according to clam 1 , wherein geopolymer is the geopolymer on the base of natural alumosilicate or a waste, raw material from the group containing blast furnace slag - clinker, shale and metakaolin.

7. Coating and/or building material according to clam 1 , wherein the compound with photocatalytic activity from the group of oxides and metal salts is titanium dioxide doped with oxides of transient metals, particularly Fe, Co, Ni, Mn, Cr, V, Ta, Nb, W and/or lathanoid oxides, particularly La, Ce, Nd, Y, Sm, Eu, Dy, which has the form of mostly spherical particles with lattice perturbances induced by dopants and it is photoactive under visible light.

8. Coating and/or building material according to clam 1, wherein the compound with photocatalytic activity from the group consisting of oxides and metal salts' are mixed oxides of the type of TiOxMeO on the base of ^:

oxides ^' of transient' metals MeO, where trie ^: Me metal is particularly Fe, ' Coy Ni,¹ Mn, Cr, V; Ta; ^{' '}Wi₉ W arid/or the lathanoid oxidέs, in particular La, Ce, Nd, Y, Sin, Eu, Dy.

9. Coating, and/or building material according to clam 1, wherein the compound with photocatalytic activity from the group consisting of oxides and metal salts creates the resulting product of homogeneous hydrolysis OfTiCl₃, TiCU, or TiOSO₄ by urea in aqueous medium

10. Coating. and/or building material according to clam 1, wherein the. compound with photocatalytic activity from the group consisting of ^■•• . ^■ oxides and metal salts is the titanioum dioxide in the form, of transparent particles, which is the product of hydrolysis OfTiCl₃ or TiCU in the medium of polar polymers, as hydroxy ethyl metaacrylate or inorganic polymers on the base of silicates, esters of silicic acid, siloxanes or silicon alkyloxides.