Reversibly crosslinked cellulose ethers and process for the production thereof by selective oxidation of vicinal OH groups

A reversibly crosslinked, water-soluble dried cellulose ether comprising hydrolysable hemiacetals, said cellulose ether having at least two different ether components,

• a) a first ether component that is at least one of an alkyl, hydroxyalkyl or carboxymethyl group and
• b) a second ether component consisting of 2-oxo-ethyl moieties and optional 2,3-dihydroxypropyl moieties, the dried aldehyde function of said 2-oxo-ethyl moieties consisting of hydrolysable hemiacetal bonded with free OH groups of the cellulose ether,
• the degree of substitution DS (2-oxo-ethyl) moiety is in the range of from 0.0001 to 0.1,
• and no low molecular weight aldehydes are liberated upon dissolution of the cellulose ether in water,
• wherein the degree of substitution DS(alkyl) is in the range from 1.2 to 2.2 and the degree of substitution MS(hydroxyalkyl) is in the range from 0.02 to 1.0.

A reversibly crosslinked, water-soluble dried cellulose ether comprising hydrolysable hemiacetals, said cellulose ether having at least two different ether components,

• a) a first ether component that is at least one of an alkyl, hydroxyalkyl or carboxymethyl group and
• b) a second ether component consisting of 2-oxo-ethyl moieties and optional 2,3-dihydroxypropyl moieties,
• the degree of substitution DS (2-oxo-ethyl) moiety is in the range of from 0.0001 to 0.1, the 2-oxo-ethyl moieties may or may not be present as hydrolysable hemiacetals, and no low molecular weight aldehydes are liberated upon dissolution of the cellulose ether in water
• wherein (i) the degree of substitution MS(hydroxyalkyl) is in the range from 1.0 to 4.0;
• (ii) the degree of substitution MS(hydroxyalkyl) is in the range from 0.8 to 3.0 and the degree of substitution DS(carboxymethyl) is in the range from 0.1 to 1.0;
• (iii) the degree of substitution MS(hydroxyalkyl) is in the range from 1.0 to 2.4 and the degree of substitution DS(carboxymethyl) is in the range from 0.2 to 0.7 or (iv) the degree of substitution DS(carboxymethyl) is in the range from 0.3 to 1.2.

A reversibly crosslinked, water-soluble dried cellulose ether having two different ether components consisting of

• a) a first dried ether component selected from a methyl, ethyl, propyl, butyl, sec-butyl, isobutyl, 2-hydroxyethyl, hydroxypropyl and/or carboxymethyl group and
• b) a second dried ether component consisting of hydrolysable hemiacetal bonds and optional 2,3-dihydroxypropyl groups,
• no low molecular weight aldehydes are liberated upon dissolution of the cellulose ether in water and
• the incipient dissolution time ranges from 7 to 27 minutes, unless accelerated by alkali.

A reversibly crosslinked, water-soluble dried cellulose ether comprising hydrolysable hemiacetals, said cellulose ether having at least two different ether components,

• a) a first ether component that is at least one of an alkyl, hydroxyalkyl or carboxymethyl group and
• b) a second ether component consisting of 2-oxo-ethyl moieties and optional 2,3-dihydroxypropyl moieties,
• the degree of substitution DS (2-oxo-ethyl) moiety is in the range of from 0.0001 to 0.1, with the dried 2-oxo-ethyl moieties consisting of hydrolysable hemiacetals,
• no low molecular weight aldehydes are liberated upon dissolution of the cellulose ether in water, and
• the final dissolution time ranges from 21 to 70 minutes unless accelerated by alkali.