Creping process utilizing low temperature-curing adhesive

A method of increasing the wet strength of a creped sheet, the method comprising:

• providing a sheet comprising cellulosic fibers, which sheet has a first side and a second side;
• applying a first low temperature-curing latex adhesive binder composition to the first side of the sheet in a fine, spaced-apart pattern occupying from about 20 to about 50 percent of the surface area of the sheet;
• applying a second low temperature-curing latex adhesive binder composition to the second side of the sheet in a fine, spaced-apart pattern occupying from about 20 to about 50 percent of the surface area of the sheet;
• adhering the second side of the sheet to a creping surface;
• and
• creping the sheet from the creping surface;
• wherein
• the sheet has a basis weight of from about 40 to about 100 grams per square meter;
• the first low temperature-curing latex adhesive binder composition comprises a first functional group-containing latex, a first functional group-reactive crosslinking agent, and a first volatile base;
• the second low temperature-curing latex adhesive binder composition is adapted to adhere the sheet to the creping surface and comprises a second functional group-containing latex, a second functional group-reactive crosslinking agent, and a second volatile base;
• and wherein the first and second low temperature-curing latex adhesive binder compositions are maintained at a pre-cure pH above about 8.0 until the sheet is creped;
• the creping surface is heated at a temperature no greater than about 100° C.;
• when the sheet is removed from the creping surface, the first and second low temperature-curing latex adhesive binder compositions have cured to a level which imparts to the creped sheet a cross-direction wet tensile strength which is at least about 50 percent that of an identical creped sheet which has been heated at about 150° C. for three minutes, in which the cross-direction wet tensile is tested in accordance with TAPPI Test Methods T494om-88 and T456om-87;
• and
• the cross-direction wet tensile strength of the creped sheet is at least about 60 grams per centimeter.

A method of increasing the wet strength of a creped sheet, the method comprising:

• providing a sheet comprising cellulosic fibers, which sheet has a first side and a second side;
• applying a first low temperature-curing latex adhesive binder composition to the first side of the sheet in a first fine, spaced-apart pattern occupying from about 20 to about 50 percent of the surface area of the sheet;
• adhering the first side of the sheet to a first creping surface;
• creping the sheet from the first creping surface;
• applying a second low temperature-curing adhesive binder composition to the second side of the sheet in a second fine, spaced-apart pattern occupying from about 20 to about 50 percent of the surface area of the sheet;
• adhering the second side of the sheet to a second creping surface;
• and
• creping the sheet from the second creping surface;
• wherein
• the sheet has a basis weight of from about 40 to about 100 grams per square meter;
• the first low temperature-curing latex adhesive binder composition is adapted to adhere the sheet to the first creping surface and comprises a first functional group-containing latex, a first functional group-reactive crosslinking agent, and a first volatile base;
• the second low temperature-curing latex adhesive binder composition is adapted to adhere the sheet to the second creping surface and comprises a second functional group-containing latex, a second functional group-reactive crosslinking agent,. and a second volatile base;
• and wherein the first and second low temperature-curing latex adhesive binder compositions are maintained at a pre-cure pH above about 8.0 until the sheet is creped;
• the first and second creping surfaces are heated at temperatures no greater than about 100° C.;
• when the sheet is removed from the second creping surface, the first and second low temperature-curing latex adhesive binder compositions have cured to a level which imparts to the creped sheet a cross-direction wet tensile strength which is at least about 50 percent that of an identical creped sheet which has been heated at about 150° C. for three minutes, in which the cross-direction wet tensile is tested in accordance with TAPPI Test Methods T494om-88 and T456om-87;
• and
• the cross-direction wet tensile strength of the creped sheet is at least about 50 grams per centimeter.