Patent ID: 8277606

Claim:
An absorbent sheet comprising a heat-treated and convolved fiber having a length weighted curl index at least about 40% higher than the fiber prior to being heat-treated and convolved, the at least 40% elevation of the length weighted curl index of the treated fiber being capable of persisting for at least 30 minutes in a disintegrator at 1% consistency at a temperature of 125° F., and the treated fiber having substantially the same strength as the fiber prior to being heat-treated and convolved, the absorbent sheet made by way of: (a) preparing a high bulk cellulosic pulp exhibiting a durable elevated curl index through the steps of (i) feeding a cellulosic pulp including Kraft fiber to a refining gap defined between opposed surfaces, at least one of the surfaces being rotatable with respect to its opposed surface; (ii) concurrently heat-treating and convolving the cellulosic pulp including Kraft fiber in the refining gap at elevated temperature and pressure under conditions selected so as to preclude substantial fibrillation and attendant paper strength and fiber bonding development to form the heat-treated and convolved fiber; and (b) incorporating the fiber so prepared into the absorbent sheet.