High stretch paper and method of producing the same

Abstract

A method for manufacturing an extensible paper, is herein described. The method comprises the steps of: providing pulp fibers in form of a pulp having a first length-weighted average curl index; mechanically treating the pulp fibers using a pulp compression process to induce fiber deformations such that the resulting pulp fibers have a second length-weighted average curl index higher than the first length-weighted average curl index; forming a wet web using the mechanically treated pulp fibers; drying the wet web under restraint to form a dried web; and adding a polymer to the dried web. An extensible paper is also described that comprises: pulp fibers having a length-weighted average curl index CLW; and a polymer in an amount of from 2 to 40 wt % based on the weight of the extensible paper; wherein the extensible paper has a Gurley air resistance below 20 s/100 mL and an elongation at break of at least 7%.

1 . A method for manufacturing an extensible paper, the method comprising the steps of:
 providing pulp fibers in form of a pulp having a first length-weighted average curl index (C LW1 ) between 0 and 0.3;   mechanically treating the pulp fibers using a pulp compression process under a pressure of from 2 to 20 bars and expending an energy of 60 to 100 kWh/tonne, to induce fiber deformations such that the resulting pulp fibers have a second length-weighted average curl index (C LW2 ) higher than the first length-weighted average curl index and between 0.1 and 0.45;   forming a wet web using the mechanically treated pulp fibers;   drying the wet web under restraint to form a dried web; and   adding a polymer to the dried web.   
     
     
         2 . The method of  claim 1 , wherein the pulp has a consistency above 20% by dry weight before the pulp compression process. 
     
     
         3 . The method of  claim 1  or  2 , wherein the pressure of the pulp compression process is from 3 to 8 bars. 
     
     
         4 . The method of any one of  claims 1  to  3 , wherein the pulp fibers are refined prior to mechanically treating. 
     
     
         5 . The method of any of  claims 1  to  3 , wherein a chemical additive is added to the pulp prior or after mechanically treating said pulp. 
     
     
         6 . The method of  claim 5 , wherein the chemical additive is a plasticizer. 
     
     
         7 . The method of  claim 5 , wherein the chemical additive is a strength additive, a sizing agent, or a cross linking agent. 
     
     
         8 . The method of  claim 7 , wherein the chemical additive is a starch, a polyacrylamide derivative, cellulose fibrils, polyamide-epichlorohydrin, melamine, urea formaldehyde, or a polyimine. 
     
     
         9 . The method of any one of  claims 1  to  8 , wherein the pulp compression process is a plug screw feeding process. 
     
     
         10 . The method of any one of  claims 1  to  8 , wherein the pulp compression process is a hammer mill, a Kollergang mill, a BIVIS device, an explosion pulping device or a revolving drum. 
     
     
         11 . The method of any one of  claims 1  to  9 , further comprising heating and/or chemically treating the pulp after mechanically treating said pulp. 
     
     
         12 . The method of any one of  claims 1  to  11 , wherein the second length-weighted average curl index (C LW2 ) is between 0.25 and 0.45. 
     
     
         13 . The method of any one of  claims 1  to  12 , wherein the polymer is a bio-based polymer, a biodegradable polymer and/or a petroleum-based polymer. 
     
     
         14 . The method of  claim 13 , wherein the petroleum-based polymer is a thermoplastic polymer or copolymer selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate, styrene-butadiene copolymers, acrylonitrile-butadiene copolymers, acrylic polymer, acrylic copolymer, vinyl acetate polymers, vinyl acetate copolymers, and vinyl chloride-vinylidene chloride copolymers. 
     
     
         15 . The method of  claim 13 , wherein the polymer is in the form of an aqueous dispersion or latex. 
     
     
         16 . The method of any one of  claims 1  to  15 , wherein the polymer is added by impregnation. 
     
     
         17 . The method of  claim 17 , wherein impregnation of the dried web comprises a web immersion in a polymer bath followed by removal of the excess polymer and a further restrained drying. 
     
     
         18 . The method of any one of  claims 1  to  17 , wherein the polymer is added in an amount of from 2 to 40 wt %. 
     
     
         19 . The method of any one of  claims 1  to  18 , wherein a cross-linking agent is added to the pulp after mechanically treating the pulp fibers. 
     
     
         20 . The method of any one of  claims 1  to  19 , wherein the pulp is a mechanical, chemi-mechanical or chemical pulp. 
     
     
         21 . The method of any one of  claims 1  to  20 , wherein the pulp is a combination of different pulps. 
     
     
         22 . An extensible paper comprising:
 pulp fibers having a length-weighted average curl index C m  of between 0.1 and 0.45; and   a polymer in an amount of from 2 to 40 wt % based on the weight of the extensible paper; wherein the extensible paper has a Gurley air resistance below 20 s/100 mL and an elongation at break of at least 7%.   
     
     
         23 . The extensible paper of  claim 22 , wherein the elongation at break is from 10% to 90%. 
     
     
         24 . The extensible paper of  claim 22  or  23 , wherein the extensible paper is a polymer-impregnated extensible paper. 
     
     
         25 . The extensible paper of any one of  claims 22  to  24 , wherein the curl index of the fibers contained in the extensible paper is of from 0.25 to 0.45. 
     
     
         26 . The extensible paper of  claim 24 , wherein the impregnated polymer is present in an amount of 10 wt %. 
     
     
         27 . The extensible paper of any one of  claims 22  to  26 , wherein the polymer is a bio-based polymer, a biodegradable polymer and/or a thermoplastic polymer or copolymer. 
     
     
         28 . The extensible paper of  claim 27 , wherein thermoplastic polymer or copolymer selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate, styrene-butadiene copolymers, acrylonitrile-butadiene copolymers, acrylic polymer, acrylic copolymer, vinyl acetate polymers, vinyl acetate copolymers, and vinyl chloride-vinylidene chloride copolymers. 
     
     
         29 . The extensible paper of any one of  claims 22  to  29 , wherein the polymer is a latex. 
     
     
         30 . An extensible paper produced by the method of any one of  claims 1 - 21 .