Process for preparing individualized, polycarboxylic acid crosslinked fibers

A process for making individualized, twisted and curled, crosslinked wood pulp cellulosic fibers, said process comprising the steps of:

• a. providing wood pulp cellulosic fibers;
• b. contacting said fibers with a solution containing a C.sub.2 -C.sub.9 polycarboxylic acid crosslinking agent, wherein said C.sub.2 -C.sub.9 polycarboxylic acid crosslinking agent is selected from the group consisting of:
• (i) aliphatic and alicyclic C.sub.2 -C.sub.9 polycarboxylic acids having at least three carboxyl groups per molecule;
• and
• (ii) aliphatic and alicyclic C.sub.2 -C.sub.9 polycarboxylic acids having two carboxyl groups per molecule and having a carbon-carbon double bond located alpha, beta to one or both of the carboxyl groups,
• wherein one carboxyl group in said C.sub.2 -C.sub.9 polycarboxylic acid crosslinking agent is separated from a second carboxyl group by either two or three carbon atoms;
• c. mechanically separating said fibers into substantially individual form;
• and
• d. drying said fibers and heating said fibers to cause said crosslinking agent to react with said fibers to form crosslink bonds while said fibers are in substantially individual form, to from intrafiber ester crosslink bonds;
• said fibers being contacted with a sufficient amount of crosslinking agent such that from about 0.5 mole % to about 10.0 mole % of the crosslinking agent, calculated on a cellulose anhydroglucose molar basis, reacts with said fibers to form said intrafiber ester crosslink bonds, said crosslinked fibers having a water retention value of from about 28 to about 60.