Paper filler composition

Patent metadata

Field	Value
Publication number	US-10100464-B2
Application number	US-201514843516-A
Country	US
Kind code	B2
Filing date	Sep 2, 2015
Priority date	May 15, 2009
Publication date	Oct 16, 2018
Grant date	Oct 16, 2018

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 700 cm3, and microfibrillating the fibrous substrate in an aqueous environment by grinding in the presence of a grinding medium which is to be removed after completion of grinding. The grinding may be carried out in the absence of grindable inorganic particulate material, 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 fiber steepness of from about 20 to about 50.

First claim

The invention claimed is:

1. A method for preparing an aqueous suspension comprising microfibrillated cellulose, the method comprising:
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. A method according to claim 1 , wherein the grinding medium is present in an amount up to about 70% by volume of the aqueous environment.

3. A method according to claim 1 , wherein the grinding medium comprises particles having an average diameter ranging from about 0.5 mm to about 6 mm.

4. A method according to claim 1 , wherein the grinding medium comprises particles having a specific gravity of at least about 2.5.

5. A method according to claim 1 , wherein the fibrous substrate comprising cellulose is present in the aqueous environment at an initial solids content of at least about 5 wt %.

6. A method according to claim 1 , wherein the initial solids content is at least about 0.5 wt %.

7. A method according to claim 1 , wherein the grinding is performed under plug flow conditions.

8. A method according to claim 1 , wherein the grinding is performed in a screened grinder.

9. A method according to claim 8 , wherein the screened grinder comprises one or more screens having a nominal aperture size of at least about 250 μm.

10. A method according to claim 1 , wherein the grinding is performed in a cascade of grinding vessels.

11. A method for preparing an aqueous suspension comprising microfibrillated cellulose, the method comprising:
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;
wherein the grinding is performed in a stirred media detritor,
wherein the grinding is carried out in the absence of grindable inorganic particulate material;
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.

12. A method according to claim 11 , wherein the stirred media detritor comprises one or more screens having a nominal aperture size of at least about 250 μm.

13. A method according to claim 11 , wherein water is added proximate to one or more quiescent zones or a classifier.

14. A method according to claim 12 , wherein the screen is located above one or more grinding zones to reduce the viscosity of the aqueous suspension comprising microfibrillated cellulose and inorganic particulate material.

Assignees

• Fiberlean Tech Ltd

Inventors

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

Classifications

• D21H19/385

  Oxides, hydroxides or carbonates · CPC title

• D21H19/38

  characterised by the pigments · CPC title

• D21D1/30

  Disc mills · CPC title

• D21H11/20

  Chemically or biochemically modified fibres · CPC title

• D21C9/007 Primary

  by mechanical or physical means · CPC title