| 摘要 |
#CMT# #/CMT# A composition (I) for coating walls, facades and the like with at least one binder (II), also contains at least one photocatalytically-active substance (III) with significant light absorption at wavelength(s) in the range 380-500 nm. #CMT# : #/CMT# An independent claim is also included for a method for the production of (I) by dispersing (III) in an inorganic binder and then mixing the resulting intermediate with an organic binder. #CMT#USE : #/CMT# In colors, plasters, paints or scumbles for application to masonry, plaster surfaces, painted surfaces, wallpaper, wood, metal, glass and/or ceramic surfaces and/or composite thermal insulation systems and/or prehung faade elements (indoors or outdoors) (claimed). #CMT#ADVANTAGE : #/CMT# A coating composition which effectively prevents the growth of algae and fungi by its photocatalytic action. #CMT#ORGANIC CHEMISTRY : #/CMT# Preferred Materials: The ratio of the absorbance (Kulbeka-Munk Function F (R-inf)) of (III) to that of (II) at at least one wavelength in the above range is more than 6.25 x 10 -> 3>, preferably more than 1 x 10 -> 2>. The binder (II) shows an absorbance of less than 0.8 (preferably less than 0.5), especially in the range 400-450 nm when (III) shows an absorbance of more than 0.005 (preferably more than 0.01, especially more than 0.02) at that wavelength under the same measurement conditions. Binder (II) comprises organic component(s) and inorganic component(s). Substance (III) contains a semiconductor, especially titanium dioxide (preferably anatase, preferably doped with another substance such as S, N and/or C so that (III) has a sulfur and/or carbon content of 0.05-4 (preferably 0.05-2, especially 0.4-1.5) wt%). (III) is obtained by mixing a titanium compound (preferably dissolved in a solvent such as water) with an organic carbon compound and then heating the mixture at 150-500 (preferably 200-300) [deg]C. (III) also shows a strong absorption band with a binding energy of 285.6 eV in the X-ray photoelectron spectrum (XPS) (referred to the O1s band at 530 eV) and only one significant signal in the g-value range of 1.97-2.05 in the ESR spectrum at 5 K, or at least one signal at a g-value of 2.002-2.004. The function (F) for (III) at 500 nm (which is proportional to absorbance) is 50% of its value at 400 nm; at 600 nm it is 20% of the value at 400 nm. The photoactivity of (I) is at least 20 (preferably at least 40, especially at least 50) %. The preferred sulfur and/or carbon content of (III) is 0.4-0.8 wt% , and this is mainly (preferably only) in the surface layer of the TiO 2 particles. Substance (III) shows a BET surface of 100-250 (preferably 130-200, especially 130-170) m 2>/g, and there are no carbonate bands in the XPS or IR spectrum of (III). Other components comprise dispersants, thickeners, foam suppressants, pigments, fillers, waterproofing agents and/or microbicidal agents, and possibly also adsorbents such as activated carbon, silica, micronised silica, silica gel, zeolites, bentonite, diatomaceous earth, foamed glass, etc. (I) may be a supercritical composition in which the relative amounts of solid and liquid components is such that the solids are not completely wetted. #CMT#EXAMPLE : #/CMT# Aqueous titanium oxide hydrate paste (35 wt% solids) obtained by the sulfate process was diluted to a stirrable consistency with water (20-25% solids), adjusted to pH 6-7 with 36 wt% sodium hydroxide solution and worked up by filtration and washing with water (to an SO 3 content of less than 1 wt%). The product was rediluted to 25% with water, mixed with 5 wt% pentaerythritol, predried to a residual moisture content of 22% and then heated in a rotary furnace (maximum temperature 300[deg]C, residence time 0.5 hour). The product showed a carbon content of 0.78 (0.82) %, PLV test values of 83.0, 11.0 and 2.6 (74.7, 9.12, 2.50) for L*, b* and a* respectively, and a BET surface of 167 (11.6) m 2>/g; the photoactivity was 86 (less than 5) %, as measured by the degree of decomposition of 4-chloro-phenol after exposure to light (wavelength at least 455 nm) for 120 minutes. Values in brackets are for a similar composition comprising commercial titanium dioxide ( Kronos 1000 (RTM: anatase; BET surface 10 m 2>/g)) with 12 wt% pentaerythritol, heated for 42 hours at 290[deg]C. |
