Paper filler composition

Patent metadata

Field	Value
Publication number	US-11377791-B2
Application number	US-201816117685-A
Country	US
Kind code	B2
Filing date	Aug 30, 2018
Priority date	May 15, 2009
Publication date	Jul 5, 2022
Grant date	Jul 5, 2022

Abstract

A method for preparing an aqueous suspension may include providing a fibrous substrate comprising cellulose having a Canadian Standard freeness equal to or less than 450 cm3, and microfibrillating the fibrous substrate in an aqueous environment by grinding in the presence of a grinding medium consisting essentially of mullite. The grinding may be carried out in the absence of grindable inorganic particulate material. The grinding medium may be present in an amount of at least about 10% by volume of the aqueous environment. The microfibrillated cellulose may have a fibre steepness of from about 20 to about 50.

First claim

The invention claimed is:

1. An aqueous composition comprising microfibrillated cellulose obtainable by a method comprising the steps of:
providing a fibrous substrate comprising cellulose, wherein the fibrous substrate comprises cellulose having a Canadian Standard freeness equal to or less than 450 cm 3 ;
microfibrillating the fibrous substrate in an aqueous environment by grinding in the presence of a grinding medium consisting essentially of mullite, and
wherein the grinding is carried out in the absence of grindable inorganic particulate matter,
wherein the grinding medium is present in an amount of at least about 10% by volume of the aqueous environment, and
wherein the microfibrillated cellulose has a fibre steepness of from about 20 to about 50.

2. The aqueous composition of claim 1 , wherein the grinding is performed in a stirred media detritor.

3. The aqueous composition of claim 2 , wherein the stirred media detritor comprises one or more screens having a nominal aperture size of at least about 250 μm.

4. The aqueous composition of claim 3 , wherein water is added proximate to one or more quiescent zones or a classifier.

5. The aqueous composition of claim 3 , wherein the screen is located above one or more grinding zone to reduce the viscosity of the aqueous composition comprising microfibrillated cellulose.

6. An essentially completely dried product obtainable by treating the aqueous suspension of claim 1 to remove about 100% by volume of the water to form an essentially completely dried product.

7. The essentially completely dried product of claim 6 , wherein treating comprises gravity or vacuum-assisted drainage.

8. The essentially completely dried product of claim 6 , wherein treating is performed with or without pressing, or evaporation, or filtration, or a combination thereof.

9. A method of preparing a papermaking composition comprising rehydrating the essentially completely dried product of claim 6 and incorporating the rehydrated product in a papermaking composition.

10. An essentially completely dried product obtainable by treating the aqueous suspension of claim 2 to remove about 100% by volume of the water to form an essentially completely dried product.

11. The essentially completely dried product of claim 10 , wherein treating comprises gravity or vacuum-assisted drainage.

12. The essentially completely dried product of claim 10 , wherein treating is performed with or without pressing, or evaporation, or filtration, or a combination thereof.

Assignees

• Fiberlean Tech Ltd

Inventors

• Husband John Claude
• Svending Per
• Skuse David Robert
• Motsi Tafadzwa
• Likitalo Mikko
• Coles Alan

Classifications

• D21D1/30

  Disc mills · CPC title

• D21D1/34

  Other mills or refiners · CPC title

• D21H19/38

  characterised by the pigments · CPC title

• D21H11/18

  Highly hydrated, swollen or fibrillatable fibres · CPC title

• D21H19/385

  Oxides, hydroxides or carbonates · CPC title