# US 8,785,158 B2 · Method for dissolving cellulose and for producing cellulose particles

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 8,785,158 B2
- Document ID: US8785158B2
- Status: Granted
- Kind: B2
- Application number: 11/922,878
- Filed: 2006-06-27
- Published: 2009-01-15
- Granted: 2014-07-22
- Earliest claimed: 2005-07-01
- Assignees: SAPPI Netherlands Services B.V.
- Applicants: Kimmo Koivunen; Petri Silenius; Janne Laine; Tapani Vuorinen
- Inventors: Kimmo Koivunen; Petri Silenius; Janne Laine; Tapani Vuorinen
- Web page: https://patentgrep.com/patent/US8785158B2

## CPC

- C12P 19/14: produced by the action of a carbohydrase {(EC 3.2.x)}, e.g. by alpha-amylase {, e.g. by cellulase, hemicellulase}
- C08J 3/05: from solid polymers
- C08J 3/122: {Pulverisation by spraying}
- C08J 3/14: by precipitation from solutions {(C08J3/122 takes precedence)}
- D21H 17/25: Cellulose
- D21H 19/42: at least partly organic
- C08J 2301/02: Cellulose; Modified cellulose
- C12P: FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE {(brewing of beer C12C; producing vinegar C12J; producing specific peptides or proteins C07K; producing enzymes C12N9/00; DNA or RNA concerning genetic engineering, vectors, e.g. plasmids, or their isolation, preparation or purification C12N15/00; measuring or testing processes involving enzymes or microorganisms C12Q; measuring or testing processes involving nucleic acid amplification reactions C12Q1/6844; fermentation processes to form a food composition, A21 or A23; compounds in general, see the relevant compound class, e.g. C01, C07)}
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- D21H: PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR

## Abstract

The invention relates to a method for dissolving cellulose e.g. for the production of regenerated cellulose products such as films, fibers, particles and the like. In said method, the cellulose material is dissolved using an enzymatic treatment, followed by a base treatment. The invention is also directed to a method for producing cellulose particles wherein cellulose dissolved as described above is sprayed or mixed into a regenerating solution for precipitating cellulose particles. Moreover, the invention relates to the use of said cellulose particles produced with this method as a filler and/or coating pigment of paper and board. The invention is also directed to methods for producing and coating paper and board.

## Claims

### Claim 1

Method for dissolving cellulose, said method consisting of the steps of
a) preparing an aqueous suspension of cellulose having a cellulose content of at least 0.1% by weight;
b) adjusting the pH value of the suspension obtained in step a) to a value of from 3 to 7;
c) adding to the suspension an enzyme with endoglucanase activity in an amount wherein the endoglucanase activity is from 20 to 2000×103 IU/kg of dry pulp to obtain a mixture;
d) heating the mixture obtained in step c) at a temperature between 40 and 65° C. until the degree of polymerization of the cellulose is not lower than a value of 100;
e) adding an alkali or alkaline earth metal hydroxide in an amount above 15% by weight to the mixture obtained in step d); and
f) heating the mixture obtained in step e) at a temperature between 15 and 50° C., to obtain a cellulose solution comprising at least 50% dissolved cellulose; and, optionally,
g) removing air and solids from the cellulose solution.

### Claim 2 (depends on 1)

Method according to claim 1, wherein the cellulose is ground cellulose.

### Claim 3 (depends on 1)

Method according to claim 1, wherein the alkali or alkaline earth metal hydroxide is NaOH in an amount ranging from 15.5 to 30%, by weight.

### Claim 4

Method of obtaining precipitated cellulose particles, said method consisting of the steps of
a) preparing an aqueous suspension of cellulose having a cellulose content of at least 0.1% by weight;
b) adjusting the pH value of the suspension obtained in step a) to a value of from 3 to 7;
c) adding to the suspension an enzyme with endoglucanase activity in an amount wherein the endoglucanase activity is from 20 to 2000×103 IU/kg of dry pulp to obtain a mixture;
d) heating the mixture obtained in step c) at a temperature between 40 and 65° C. until the degree of polymerization of the cellulose is not lower than a value of 100;
e) adding an alkali or alkaline earth metal hydroxide in an amount above 15% by weight to the mixture obtained in step d);
f) heating the mixture obtained in step e) at a temperature between 15 and 50° C., to obtain a cellulose solution comprising at least 50% dissolved cellulose; and
g) spraying or mixing the cellulose solution obtained in step f) into an acid solution to obtain a suspension containing precipitated cellulose particles, and, optionally, subjecting the precipitated cellulose particles in the suspension to crosslinking or derivatization; and, optionally,
h) washing and/or drying the precipitated cellulose particles of step g).

### Claim 5 (depends on 4)

Method according to claim 4, wherein cellulose content of the cellulose solution obtained in step g), and droplet size in case of spraying, or mixing speed in case of mixing are selected such that the obtained precipitated cellulose particles have particle sizes ranging between 0.05 and 10 μm.

### Claim 6 (depends on 4)

Method according to claim 4, wherein the crosslinking is achieved by adding 5 moles of formaldehyde per one mole of glucose units to the suspension containing precipitated cellulose particles and heating the resulting suspension at 40 to 60° C. to obtain precipitated crosslinked cellulose particles.