Modified cellulose ethers and the use thereof in dispersion paints

A water-soluble cellulose ether containing at least one fluorine-free radical attached via an ether link and selected from the group hydroxyethyl, hydroxypropyl, methyl, ethyl and carboxymethyl, and a hydrophobic substituent which comprises a fluorine-containing alkyl radical containing 3 to 24 carbon atoms, the fluorine content being 0.05 to 5, by weight, based on the dry weight of the cellulose ether wherein the hydrophobic substituent attached to the cellulose ether has one of the formulae selected from the group consisting of

• (a) R--CH(OH)--CH.sub.2 --O--cellulose ether
• (b) R.sup.1 --CHF--CFR--O--cellulose ether
• (c) R--CHF--CFR.sup.1 --O--cellulose ether
• (d) R--O--cellulose ether
• (e) R--O--CH.sub.2 --CH(OH)--CH.sub.2 --O--cellulose ether
• (f) Y--CHX--CX.sub.2 --O--cellulose ether
• (g) Y--CHX--CXR.sup.2 --O--cellulose ether
• (j) HCRR.sup.2 --CO--O--cellulose ether
• (l) R--NH--CO--O--cellulose ether
• in which R and R.sup.1 are each a (C.sub.1 -C.sub.22)alkyl radical and R.sup.2 is either H or a (C.sub.1 -C.sub.22)alkyl radical, the total number of the carbon atoms of the alkyl groups of the formulae (b), (c) and (j) being 3 to 24,
• X is fluorine and/or hydrogen and
• Y is --CN or --CO.sub.2 R.sup.3, R.sup.3 being a (C.sub.1 -C.sub.22)alkyl radical, and in the formulae (a) to (g) at least 3 carbon atoms, in the formula (j) and (l) at least 2 carbon atoms, of the substituents are linked with fluorine atoms.