Process for treating microfibrillated cellulose

Abstract

An aqueous suspension or a papermaking composition or paper product including microfibrillated cellulose, and optionally inorganic particulate material, obtained by a process comprising subjecting an aqueous suspension comprising microfibrillated cellulose to high shear, wherein the high shear is generated, at least in part, by a moving shearing element, to improve the paper burst strength enhancing attributes of the microfibrillated cellulose, wherein microfibrillated cellulose of the aqueous suspension comprising microfibrillated cellulose has, prior to high shear, a fibre d 50 of at least about 50 μm and a fibre steepness of from about 20 to about 50, and wherein the term “high shear” means a shear rate of at least 10,000 s −1 to about 120,000 s −1 .

1 - 15 . (canceled) 
     
     
         16 . An aqueous suspension comprising microfibrillated cellulose obtained by a process comprising subjecting an aqueous suspension comprising microfibrillated cellulose to high shear, wherein the high shear is generated, at least in part, by a moving shearing element, to improve the paper burst strength enhancing attributes of the microfibrillated cellulose, wherein microfibrillated cellulose of the aqueous suspension comprising microfibrillated cellulose has, prior to high shear, a fibre do of at least about 50 μm and a fibre steepness of from about 20 to about 50, and wherein the term “high shear” means a shear rate of at least 10,000 s −1  to about 120,000 s −1 , and wherein, following high shear, the paper burst strength enhancing attributes of the microfibrillated cellulose is increased by at least about 1% for a paper product made from a papermaking composition comprising microfibrillated cellulose made after said high shear versus a comparable paper product comprising an equivalent amount of microfibrillated cellulose prior to said high shear. 
     
     
         17 . The aqueous suspension according to  claim 16 , further comprising inorganic particulate material. 
     
     
         18 . The aqueous suspension according to  claim 16 , wherein the moving shearing element is housed within a high shear rotor/stator mixing apparatus, and the process comprises subjecting the aqueous suspension comprising microfibrillated cellulose to high shear in said rotor/stator mixing apparatus to improve the paper burst strength enhancing attributes of the microfibrillated cellulose. 
     
     
         19 . The aqueous suspension according to  claim 17 , wherein the moving shearing element is housed within a high shear rotor/stator mixing apparatus, and the process comprises subjecting the aqueous suspension comprising microfibrillated cellulose to high shear in said rotor/stator mixing apparatus to improve the paper burst strength enhancing attributes of the microfibrillated cellulose. 
     
     
         20 . A papermaking composition obtained by a process comprising subjecting an aqueous suspension comprising microfibrillated cellulose to high shear, wherein the high shear is generated, at least in part, by a moving shearing element, to improve the paper burst strength enhancing attributes of the microfibrillated cellulose, wherein microfibrillated cellulose of the aqueous suspension comprising microfibrillated cellulose has, prior to high shear, a fibre d 50  of at least about 50 μm and a fibre steepness of from about 20 to about 50, and wherein the term “high shear” means a shear rate of at least 10,000 s −1  to about 120,000 s −1 , and wherein, following high shear, the paper burst strength enhancing attributes of the microfibrillated cellulose is increased by at least about 1% for a paper product made from a papermaking composition comprising microfibrillated cellulose made after said high shear versus a comparable paper product comprising an equivalent amount of microfibrillated cellulose prior to said high shear 
     
     
         21 . A paper product obtained by a process comprising subjecting an aqueous suspension comprising microfibrillated cellulose to high shear, wherein the high shear is generated, at least in part, by a moving shearing element, to improve the paper burst strength enhancing attributes of the microfibrillated cellulose, wherein microfibrillated cellulose of the aqueous suspension comprising microfibrillated cellulose has, prior to high shear, a fibre d 50  of at least about 50 μm and a fibre steepness of from about 20 to about 50, and wherein the term “high shear” means a shear rate of at least 10,000 s −1  to about 120,000 s −1 , and wherein, following high shear, the paper burst strength enhancing attributes of the microfibrillated cellulose is increased by at least about 1% for a paper product made from a papermaking composition comprising microfibrillated cellulose made after said high shear versus a comparable paper product comprising an equivalent amount of microfibrillated cellulose prior to said high shear, wherein the paper product has a first burst strength which is greater than a second burst strength of a comparable paper product comprising an equivalent amount of microfibrillated cellulose prior to high shear. 
     
     
         22 . The paper product according to  claim 21 , wherein the paper product comprises from about 0.1 to about 5% by weight microfibrillated cellulose. 
     
     
         23 . The paper product according to  claim 22 , further comprising up to about 50% by weight inorganic particulate material. 
     
     
         24 . The papermaking composition according to  claim 20 , wherein the paper product comprises from about 0.1 to about 5% by weight microfibrillated cellulose. 
     
     
         25 . The papermaking composition according to  claim 24 , further comprising up to about 50% by weight inorganic particulate material. 
     
     
         26 . The aqueous suspension of  claim 16 , wherein the aqueous suspension comprising microfibrillated cellulose is obtained by a process further comprising microfibrillating a fibrous substrate comprising cellulose in an aqueous environment in the presence of a grinding medium. 
     
     
         27 . The aqueous suspension of  claim 17 , wherein the aqueous suspension comprising microfibrillated cellulose is obtained by a process further comprising microfibrillating a fibrous substrate comprising cellulose in an aqueous environment in the presence of a grinding medium. 
     
     
         28 . The aqueous suspension according to  claim 17 , wherein the inorganic particulate material is selected from the group consisting of: an alkaline earth metal carbonate or sulphate, calcium carbonate, natural calcium carbonate, precipitated calcium carbonate, magnesium carbonate, dolomite, gypsum, a hydrous kandite clay, kaolin, halloysite, ball clay, an anhydrous kandite clay, metakaolin, fully calcined kaolin, talc, mica, perlite, diatomaceous earth, magnesium hydroxide, aluminum trihydrate, or combinations thereof. 
     
     
         29 . The aqueous suspension according to  claim 28 , wherein (i) the inorganic particulate material is calcium carbonate, or (ii) the inorganic particulate material is kaolin. 
     
     
         30 . The aqueous suspension according to  claim 29 , wherein (i) the inorganic particulate is calcium carbonate, and at least about 50 wt. % of the calcium carbonate has an equivalent spherical diameter of less than about 2 μm, or (ii) the inorganic particulate material is kaolin, and at least about 50 wt. % of the kaolin has an equivalent spherical diameter of less than about 2 μm. 
     
     
         31 . The papermaking composition according to  claim 20 , further comprising inorganic particulate material. 
     
     
         32 . The papermaking composition according to  claim 31 , wherein the inorganic particulate material is selected from the group consisting of: an alkaline earth metal carbonate or sulphate, calcium carbonate, natural calcium carbonate, precipitated calcium carbonate, magnesium carbonate, dolomite, gypsum, a hydrous kandite clay, kaolin, halloysite, ball clay, an anhydrous kandite clay, metakaolin, fully calcined kaolin, talc, mica, perlite, diatomaceous earth, magnesium hydroxide, aluminum trihydrate, or combinations thereof. 
     
     
         33 . The papermaking composition according to  claim 32 , wherein (i) the inorganic particulate material is calcium carbonate, or (ii) the inorganic particulate material is kaolin. 
     
     
         34 . The papermaking composition according to  claim 33 , wherein (i) the inorganic particulate is calcium carbonate, and at least about 50 wt. % of the calcium carbonate has an equivalent spherical diameter of less than about 2 μm, or (ii) the inorganic particulate material is kaolin, and at least about 50 wt. % of the kaolin has an equivalent spherical diameter of less than about 2 μm. 
     
     
         35 . The paper product according to  claim 23 , wherein the inorganic particulate material is selected from the group consisting of: an alkaline earth metal carbonate or sulphate, calcium carbonate, natural calcium carbonate, precipitated calcium carbonate, magnesium carbonate, dolomite, gypsum, a hydrous kandite clay, kaolin, halloysite, ball clay, an anhydrous kandite clay, metakaolin, fully calcined kaolin, talc, mica, perlite, diatomaceous earth, magnesium hydroxide, aluminum trihydrate, or combinations thereof. 
     
     
         36 . The paper product according to  claim 35 , wherein (i) the inorganic particulate material is calcium carbonate, or (ii) the inorganic particulate material is kaolin. 
     
     
         37 . The paper product according to  claim 36 , wherein (i) the inorganic particulate is calcium carbonate, and at least about 50 wt. % of the calcium carbonate has an equivalent spherical diameter of less than about 2 μm, or (ii) the inorganic particulate material is kaolin, and at least about 50 wt. % of the kaolin has an equivalent spherical diameter of less than about 2 μm.