Crosslinked cellulose products and method for their preparation

A chemically crosslinked cellulosic product, comprising:

• unrefined cellulose fibers having a moisture content of greater than about 30 percent before drying and crosslinking the product at a temperature of greater than about 100.degree. C. for a period of from about 1 minute to about 5 minutes;
• a cationic debonding agent in an amount of about 0.1-20 kg/ton of fiber;
• and
• a water soluble or water dispersible latent cellulose crosslinking agent, wherein the crosslinking agent is a polycarboxylic acid or is selected from the group of urea derivatives consisting of methylolated urea, methylolated cyclic ureas, methylolated lower alkyl substituted cyclic ureas, dihydroxy cyclic ureas, lower alkyl substituted dihydroxy cyclic ureas, and methylolated dihydroxy cyclic ureas;
• and mixtures thereof, the crosslinking agent being added in an amount of about 0.1-20 kg/ton of fiber.

A cellulosic product comprising:

• (1) a first, chemically crosslinked cellulosic fiber fraction comprising (a) unrefined cellulose fiber having a water content of greater than about 10 percent prior to being crosslinked;
• (b) a cationic debonding agent in an amount of from about 0.1 kg/ton to about 200 kg/ton of fiber;
• and (c) a water soluble or water dispersible latent cellulose crosslinking agent, wherein the crosslinking agent is a polycarboxylic acid or is selected from the group of urea derivatives consisting of methylolated urea, methylolated cyclic ureas, methylolated lower alkyl substituted cyclic ureas, dihydroxy cyclic ureas, lower alkyl substituted dihydroxy cyclic ureas, and methylolated dihydroxy cyclic ureas;
• and mixtures thereof, the crosslinking agent being added in an amount of from about 0.1 kg/ton to about 200 kg/ton of fiber;
• and
• (2) a second fiber fraction comprising conventional fiber furnish.

A method of making a crosslinked cellulose product which comprises the steps of:

• providing a sheet of wet, unrefined cellulose fibers having a moisture content greater than 30%;
• providing within said fibers a debonding agent and a water soluble or water dispersible latent cellulose crosslinking agent, wherein the crosslinking agent is added to the cellulosic sheet in the wet press section of a paper machine, and wherein the crosslinking agent is a polycarboxylic acid or is selected from the group of urea derivatives consisting of methylolated urea, methylolated cyclic ureas, methylolated lower alkyl substituted cyclic ureas, dihydroxy cyclic ureas, lower alkyl substituted dihydroxy cyclic ureas, and methylolated dihydroxy cyclic ureas;
• and mixtures thereof;
• and
• immediately after providing the crosslinking agent, drying the fibers at an elevated temperature to simultaneously dry the fibers and dry crosslink the fibers with the crosslinking agent.

A method of making a crosslinked cellulose product which comprises the steps of:

• providing wet, unrefined cellulose fibers having a moisture content greater than 30%;
• providing within said fibers a debonding agent, in an amount of from about 1-10 kg/ton of cellulose fiber, and a water soluble or water dispersible latent cellulose crosslinking agent, wherein the crosslinking agent is a polycarboxylic acid or is selected from the group of urea derivatives consisting of methylolated urea, methylolated cyclic ureas, methylolated lower alkyl substituted cyclic ureas, dihydroxy cyclic ureas, lower alkyl substituted dihydroxy cyclic ureas, and methylolated dihydroxy cyclic ureas;
• and mixtures thereof;
• and
• immediately after providing the crosslinking agent, drying the fibers at an elevated temperature to simultaneously dry the fibers and dry crosslink the fibers with the crosslinking agent.

A method of making a crosslinked cellulose product which comprises the steps of:

• providing wet, unrefined cellulose fibers having a moisture content greater than 30%;
• providing within said fibers a debonding agent, in an amount of from about 20-200 kg/ton of cellulose fiber, and a water soluble or water dispersible latent cellulose crosslinking agent, wherein the crosslinking agent is a polycarboxylic acid or is selected from the group of urea derivative consisting of methylolated urea, methylolated cyclic ureas, methylolated lower alkyl substituted cyclic ureas, dihydroxy cyclic ureas, lower alkyl substituted dihydroxy cyclic ureas, and methylolated dihydroxy cyclic ureas;
• and mixtures thereof, wherein the crosslinking agent is added in an amount of about 2-200 kg/ton of fiber;
• and
• immediately after providing the crosslinking agent, drying the fibers at an elevated temperature to simultaneously dry the fibers and dry crosslink the fibers with the crosslinking agent.