Patent ID: 6916507

Claim:
An aqueous water repellent for the treatment of a substrate, comprising the product of co-hydrolytic condensation of a mixture consisting of (A) 100 parts by weight of an organosilicon compound having the following general formula (1): (R 1 ) a (OR 2 ) b SiO (4-a-b)/2 (1) wherein R 1 is a methyl group, R 2 is an alkyl group having 1 to 4 carbon atoms, letter a is a positive number of 0.75 to 1.5, b is a positive number of 0.2 to 3 and a+b is from more than 0.9 to 4, and (B) 0.5 to 49 parts by weight of an amino group-containing alkoxysilane having the following general formula (2): R 3 R 4 NR 5 —SiR 6 n (OR 2 ) 3-n (2) wherein R 2 is as defined above, R 3 and R 4 each are independently hydrogen or an alkyl or aminoalkyl group having 1 to 15 carbon atoms, R 5 is a divalent hydrocarbon group having 1 to 18 carbon atoms, R 6 is an alkyl group having 1 to 4 carbon atoms, and n is 0 or 1, or a partial hydrolyzate thereof, components (A) and (B) being used such that 0.01 to 0.3 mol of Si atoms in component (B) are available per mol of Si atoms in component (A), the co-hydrolytic condensation being effected in the presence of an organic acid or inorganic acid.