Patent ID: 6960660

Claim:
A water-soluble cellulose ether characterized in that the number of undissolved fibers having a size of 16 to 200 μm in a 0.1 wt % aqueous solution at 25° C. is up to 350 fibers/2 ml, said water-soluble cellulose ether is selected from the group consisting of a hydroxypropylcellulose containing 50 to 70% by weight of hydroxypropoxyl groups, a hydroxyethylcellulose containing 30 to 60% by weight of hydroxyethoxyl groups, a hydroxypropylmethylcellulose containing 19 to 30% by weight of methoxyl groups and 4 to 20% by weight of hydroxypropoxyl groups, a hydroxyethylmethylcellulose containing 19 to 30% by weight of methoxyl groups and 9 to 20% by weight of hydroxyethoxyl groups, and a hydroxyethylethylcellulose containing 11 to 21% by weight of ethoxyl groups and 40 to 57% by weight of hydroxyethoxyl groups.