Aqueous dispersion of metal-oxide powder for application on substrate for e.g. photocatalytic applications, contains viscosity regulator and water-soluble binding agent, both being completely removable by thermal treatment

摘要

An aqueous dispersion containing metal-oxide powder, contains a viscosity regulator and a water-soluble binding agent. The viscosity regulator and the binding agent can be completely removed by thermal treatment. Independent claims are also included for the following: (1) process for producing the aqueous dispersion comprising generating a predispersion by charging metal-oxide powder, continuously or all at once, under dispersing conditions into a receiving flask that contains water, adding viscosity regulator, during or after the addition of metal-oxide powder, until the desired viscosity arises; and adding, to the predispersion, an aqueous solution of the binding agent such that the proportion of the binding agent is 0.05-5 wt.%, optionally an aqueous solution of the defoaming agent, and optionally small quantities of viscosity regulator for adjusting the original pH value in order to obtain the dispersion; (2) individual metal-oxide layer obtained using the above dispersion, having a layer thickness of at least 2.5 mu m on a substrate; (3) process for producing a metal-oxide layer on a substrate, comprising applying by dip coating an individual layer onto a substrate using the above dispersion to form a green body; subsequently drying the green body at less than 100[deg]C; subsequently heating to temperature at which the binding agent and optionally the defoaming agent are partially or completely removed from the green body; and subsequently sintering; and (4) use of metal oxide for materials having very low coefficients of expansion (ultra-low-expansion materials, ULE materials), for photocatalytic applications, as coating for self-cleaning mirrors (superhydrophilic constituent), for optical items such as lenses, as a seal for gases and liquids, and as mechanical protective layer, as use in composite materials.