WO2009129760A1

WO2009129760A1 - A particle surface • coated with photocatalytic oxides or metal salts and a coating and/or building material comprising the same

Info

Publication number: WO2009129760A1
Application number: PCT/CZ2009/000058
Authority: WO
Inventors: Petr Ratajsky
Original assignee: Rokospol A.S.
Priority date: 2008-04-25
Filing date: 2009-04-22
Publication date: 2009-10-29
Also published as: CZ2008261A3

Abstract

A particle for a coating composition or a building material catalytically photodegrading environmental pollutants, wherein the particle is at least partically surface coated with oxides or metal salts in nano crystalline form. Coating compositions and building materials comprising theses particles.

Description

A PARTICLE SURFACE ■ COATED WITH PHOTOCATALYTIC OXIDES OR METAL SALTS AND A COATING AND/OR BUILDING MATERIAL COMPRISING THE SAME

Field of the invention

The invention relates to a component of coating and/or building material active from the aspect of catalysis of the photodegradation of pollutants in the air. The invention also relates to the coating and/or building material containing this component.

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 are known that contain photocatalytically active titanium dioxide as an admixture .

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 titanium dioxide. In this area, 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 - the 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 massive and thin-layer coatings and structures made of 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 protection of building surfaces. In this respect no solution has been hitherto known that would have an active positive influence on the reduction of pollutants - air contaminants, especially the emission gasses and volatile matters originating from human activities (as solvents), flame retardants, etc., and/or self-cleaning effect.

Summary of the invention

A component of the coating and/or building material active from the aspect of photodegradation of pollutants in the air contributes to a considerable extent to the elimination of the above shortcomings of the hitherto state of art. The gist of the invention consist in the fact that at least a part of the total amount of particles of this component is provided on its surface or at least on a part of it with a coat of substance from the group consisting of oxides and metal salts in nanocrystalline form with photocatalytic activity in the visible part of solar spectrum.

The particles provided on their surface with a coat of substance from the group consisting of oxides and metal salts with photocatalytic activity may be the particles of the filler (of spathic, fibrous or spherical structure) and/or particles of the pigment.

A compound with photocatalytic activity from the group containing oxides and metal salts may be preferably titanium dioxide doped with oxides of transient metals, in particular 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 by visible light.

Another variant of the compounds with photocatalytic activity from the group containing oxides and metal salts are mixed oxides of the type of TiOxMeO on the base of titanium oxide doped with oxides of transient metals (MeO), in which the Me metal is particularly Fe, Co, Ni, Mn, Cr, V, Ta, Nb, W and/or the lathanoid oxides, in particular La, Ce, Nd, Y, Sin, Eu, Dy.

The photoactive substance from the group of oxides and metal salts may also be the resulting product of homogeneous analysis Of TiCl₃ or TiCl₄ by urea in aqueous medium or also titanium dioxide in the form of transparent particles, which is the product of hydrolysis of T1CI₃ 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 particles of the filler may be preferably, but not necessarily, the particles active from the aspect of setting of the substance - primarily the particles of at least one substance from the group comprising clinker, shale, metakaςlin, zeolite, talc, mica,,,wollastonite, glass, blast furnace slag, silica, kaolin and lime stone.

The main benefit of the component of the coating and/or building material according to this invention is a substantial enlargement of the surface of the active component according to the type and form of the filler and/or pigment as a carrier, substantial saving due, to the thin coat of the active component and thus, with a comparable content of the active component, reinforcement of the; photocatalytic effect.

Examples of embodiments of the invention Example 1

Silicate facing or interior coating containing nanocrystalline titanium dioxide: disperse 60 to 80 parts by mass of standard white pigment (zinc oxide, etc., titanium dioxide etc.) and 300 , parts by mass of mineral filler of specified fineness in 200 up to 240 parts by mass of water to which 3 parts by mass of dispersing agent have been added. Add 1 to 50 parts by mass of powdered mica coated with nanocrystalline titanium oxide photoactive in the region of visible light (KFD embodiment) to the obtained homogeneous mixture. After a short dispergation, add 250 up to 300 parts by mass of 20 to 30% dissolution of potassium water-glass. The obtained paint may be filled up with thickener, antifoaming agent, spreading agent etc., and possibly also with the polymeric dispersion of organic or inorganic type in the amount of 0,1 up to 30 % per dry matter.

This facing coating applied with a brush, a roller or by spraying, after the contained water-glass has been allowed to dry and mature thoroughly - by neutralizing it with atmospheric carbon dioxide, will form a well permeable, long-life weather-resistant surface layer with a long-term photocatalytic effect reducing the content of emission gases from the surrounding air.

Example 2

Coating containing nanocrystalline titanium oxide for KDF treatment of roofs, bridges and civil engineering structures: mix the transparent base for top surface treatment of rooftop concrete tiles with 0.1 up to 50 percent by mass of dry powder nanocrystalline titanium oxide, photoactive in the region of visible light (KFD). This compound is then used to perform the final treatment (overpainting) in the thickness of the dry film of 5 up to 30 μm, depending on the smoothness of the tiles surface. The created layer is sufficiently compact to ensure its resistance to water and its moderate thickness so that it could form a film partially permeable to gases and steam in the course of drying. 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 polyacrylic and polymetaacrylic acid as a binder for the preparation of the specified transparent base, or inorganic binders on the base of silicates, silicic esters, siloxanes or silicon alkyloxides. They can be well combined with ground glass coated with photoactive nanocrystaliine titanium dioxide to ensure high permeability to gases and, at the same time, high hydrophility necessary to enable the creation of the so-called "self-cleaning ability".

Example 3

Facing or interior coating containing nanocrystaliine titanium dioxide: disperse 60 to 80 parts by mass of standard white pigment (zinc oxide, etc., titanium dioxide etc.) and 300 parts by mass of mineral filler of specified fineness in 200 up to 240 parts by mass of water to which 2 parts by mass of dispersing agent have been added. Add 1 to 50 parts by mass of talc coated with nanocrystaliine titanium dioxide photoactive in the region of visible light (KFD embodiment) to the obtained homogeneous mixture. After a short dispergation, add 250 up to 400 parts by mass of 20 to 30% dissolution of inorganic binder on the base of hydroxyderivatives of acrylic or metaacrylic acid. The obtained paint may be filled up with thickener, antifoaming agent, spreading agent etc., and possibly also with the polymeric dispersion of organic or inorganic type in the amount of 0,1 up to 30 % per dry matter.

This facing or interior coating applied with a brush, a roller or by spraying, after the contained binder has been allowed to dry and mature thoroughly will form a well permeable, long-life, weather-resistant surface layer with a long-term photocatalytic effect reducing the content of emission gases from the environment and the coating itself will be resistant to the photocatalytic decomposition of the binder.

Example 4

Plastering containing binders coated with nanocrystalline titanium dioxide are analogous to the facing and interior coatings presented in Example 1.

Example 5

Facing boards, ceramics, glass and other building components may be provided with surface layers (treatments) containing filler coated with photoactive nanocrystalline titanium oxide, analogous to example 2.

Example 6

Building material or jointing compound containing one or more fillers or pigments, which are partially or completely coated with photoactive nanocrystalline titanium oxide.

Claims

P A T E N T C L A I M S

1. A component of coating and/or building material active from the aspect of catalysis of photodegradation of pollutants in the environment, wherein at least a part of the total amount of particles of this component is provided on its surface or at least on a part of it with a coat of substance from the group consisting of oxides and metal salts in nanocrystalline form with photocatalytic activity in the visible region of the solar spectrum.

2. A component of coating and/or building material according to claim 1, wherein the particles provided on its whole surface or at least on a part of it, with a coat comprising a substance from the group consisting of oxides and metal salts with photocatalytic activity are particles of filler and/or pigment.

3. A component of coating and/or building material according to claim 2, wherein the particles of the filler are particles of spathic, fibrous or spherical structure.

4. A component of coating and/or building material according to claiiη 1, wherein the substance from the group of oxides and metal salts with photocatalytic activity 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.

5. A component of coating and/or building material according to claim 1, wherein the compound with photocatalytic activity from the group of oxides and metal salts are mixed oxides of the type of TiOxMeO on the base of titanium oxide doped with oxides of transient metals (MeO), where the metal (Me) is particularly Fe, Co, Ni, Mn, Cr, V, Ta, Nb, W and/or the lathanoid oxides, in particular La, Ce, Nd, Y, Sin, Eu, Dy.

6. A component of coating and/or building material according to clam 1, wherein the compound with photocatalytic activity from the group of oxides and metal salts creates the resulting product of homogeneous hydrolysis of T1CI₃, TiCl₄, or TiOSO₄ by urea in aqueous medium.

7. A component of coating and/or building material according to clam 1, wherein the compound with photocatalytic activity from the group of oxides and metal salts in the form of transparent particles, which is the product of hydrolysis of T-CI₃ or TiCl₄ in the medium of polar polymers, as hydroxyethyi metaacrylate or inorganic binders on the base of silicates, esters of silicic acid, siloxanes or silicon alkyloxides.

8. A component of coating and/or building material according to claim 2, wherein the particles of the filler are the particles active from the aspect setting of the substance.

9. A component of coating and/or building material according to claim 8, wherein the particles of the filler are the particles of at least one substance from the group comprising clinker, shale, metakaolin, zeolite, talc, mica, wollastonite, glass, blast furnace slag, silica and lime stone.

10. Coating and/or building material containing a component according to claims 1 to 9.