PREPARATION OF HIGHGLY HYDROPHILIC LAYER, AND HIGHLY HYDROPHILIC LAYER

摘要

PROBLEM TO BE SOLVED: To impart both water resistance and hydrophilicity each at a high level to a hydrophilic layer by firstly forming a hydrophilic layer containing alumina particles and secondly treating this hydrophilic layer with a liquid containing silicic acid.;SOLUTION: As an alumina particle for a hydrophilic layer formed first, any kind of alumina, provided that one or more than one of aluminum oxide hydrate and aluminum hydroxide forms 20-100 wt.% of the total alumina can be used. Preferably, 20-100 wt.% of the alumina particles are sol having an average particle size of not more than 200 nm. Alumina can solely give a hydrophilic layer, but preferably it is used together with other inorganic fillers, sol or the like so that it is contained in an amount of 5-90 wt.% in the hydrophilic layer. A liquid containing silicic acid for a second step is one containing a silicate salt or silicic acid. The increase in the amount of silicic acid in the hydrophilic layer after the treatment with the liquid containing silicic acid is preferably 5-5,000 mg/m2.;COPYRIGHT: (C)2000,JPO