# US 11,299,556 B2 · Method for the production of a spinning dope composition

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- Number: US 11,299,556 B2
- Document ID: US11299556B2
- Status: Granted
- Kind: B2
- Application number: 16/093,271
- Filed: 2017-04-12
- Published: 2019-06-20
- Granted: 2022-04-12
- Earliest claimed: 2016-04-14
- Assignees: Treetotextile AB
- Applicants: Treetotextile AB
- Inventors: Carina Olsson; Bengt Hagström; Tobias Köhnke
- Web page: https://patentgrep.com/patent/US11299556B2

## CPC

- C08B 1/003: {Preparation of cellulose solutions, i.e. dopes, with different possible solvents, e.g. ionic liquids (solutions used in the manufacture of monocomponent artificial filaments or cellulose or derivatives thereof D01F2/02)}
- B01F 21/02: {Methods}
- B01F 33/821: {with consecutive receptacles}
- C08J 3/05: from solid polymers
- D01D 1/02: Preparation of spinning solutions
- D01F 2/02: from solutions of cellulose in acids, bases or salts
- C08K 2003/2296: {of zinc}
- D10B 2201/22: made from cellulose solutions
- C08B: POLYSACCHARIDES; DERIVATIVES THEREOF (polysaccharides containing less than six saccharide radicals attached to each other by glycosidic linkages C07H; fermentation or enzyme-using processes C12P19/00; sugar industry C13; production of cellulose D21)
- B01F: MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING (mixing paints B44D3/06)
- 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)
- D01D: MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01F: CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)
- D10B: INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES

## Abstract

The present invention describes a method for the production of a spinning dope composition, said method comprising a homogenization involving vigorous mixing of a cellulosic pulp material in alkali solution, vigorous mixing implying supplying a power density to agitators used in the homogenization step of at least 150 k W/m3 (k W supplied to agitators per mixed unit of liquid volume), and thereafter a dissolution involving mixing of the cellulosic pulp material in the alkali solution to obtain a spinning dope composition, wherein the power density supplied to agitators used in the dissolution step is maximum 75 k W/m3 (k W supplied to agitators per mixed unit of liquid volume); and wherein the cellulosic pulp material in alkali solution is kept at a temperature of less than 0° C. during the homogenization and during at least part of the dissolution. The present invention is also directed to a system intended for the production of a spinning dope composition.

## Claims

### Claim 1

A method for the production of a spinning dope composition, said method comprising
a homogenization involving vigorous mixing of a cellulosic pulp material in alkali solution, vigorous mixing implying supplying a power density of at least 150 kW/m3 (kW supplied to agitators per mixed unit of liquid volume) to agitators used in the homogenization, and thereafter
a dissolution involving mixing of the cellulosic pulp material in the alkali solution to obtain a spinning dope composition, wherein the power density supplied to agitators used in the dissolution is maximum 75 kW/m3 (kW supplied to agitators per mixed unit of liquid volume);
and wherein the cellulosic pulp material in alkali solution is kept at a temperature of less than 0° C. during the homogenization and during at least part of the dissolution.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the power density supplied to agitators used in the homogenization is in a range of 150-4000 kW/m3, and wherein the power density supplied to agitators used in the dissolution is maximum 50 kW/m3.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the dissolution is performed during a time period sufficient for substantially complete dissolution of cellulose polymers of the cellulosic pulp material in the alkali solution.

### Claim 4 (depends on 1)

The method according to claim 1, wherein the homogenization is performed during a time of less than 120 s.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the dissolution is performed during a time of at least 4 minutes.

### Claim 6 (depends on 1)

The method according to claim 1, wherein the power density supplied to agitators used in the homogenization is in a range of 150-2500 kW/m3 (kW supplied to agitators per mixed unit of liquid volume).

### Claim 7 (depends on 1)

The method according to claim 1, wherein the power density supplied to agitators used in the dissolution is in a range of 2-50 kW/m3.

### Claim 8 (depends on 1)

The method according to claim 1, wherein:
a product of power density * residence time is in a range of 4000-20000 (kW*s)/m3, in a power density range of 200-2000 kW/m3, and for residence times in a range of 1-30 seconds in the homogenization; and
the product of power density * residence time is in a range of 4000-25000 (kW*s)/m3 in a power density range of 4-50 kW/m3 and for residence times in a range of 240-1800 seconds in the dissolution.

### Claim 9 (depends on 1)

The method according to claim 1, wherein temperature in the cellulosic pulp material in alkali solution is held within a range of from −8 to −3° C. during the homogenization and during at least part of the dissolution.

### Claim 10 (depends on 1)

The method according to claim 1, wherein the vigorous mixing in the homogenization involves high shear mixing with a rotation speed of at least 1000 rpm.

### Claim 11 (depends on 1)

The method according to claim 1, wherein the mixing in the dissolution is performed with a rotation speed below 300 rpm.

### Claim 12 (depends on 1)

The method according to claim 1, wherein the cellulosic pulp material being processed is a non-derivatised or low-derivatised cellulose pulp.

### Claim 13 (depends on 1)

The method according to claim 1, wherein the method also comprises at least one refining performed subsequent to the dissolution, said refining providing viscous dissipation and a temperature increase to the spinning dope composition by shearing.

### Claim 14 (depends on 13)

The method according to claim 13, wherein the temperature increase in the refining is 0.2-10° C.

### Claim 15 (depends on 13)

The method according to claim 13, wherein the refining is performed with a power density in a range of 1000-8000 kW/m3.

### Claim 16 (depends on 13)

The method according to claim 13, wherein the refining is performed with a power density in a range of 2000-6000 kW/m3.

### Claim 17 (depends on 13)

The method according to claim 13, wherein a product of power density * residence time is in a range of 2000-15000 (kW*s)/m3 in a power density range of 1000-6000 kW/m3, and for residence times in a range of 0.5-5 seconds in the refining.

### Claim 18 (depends on 13)

The method according to claim 13, wherein at least one further dissolution is performed subsequent to at least one of said at least one refining.

### Claim 19 (depends on 1)

The method according to claim 1, wherein the cellulosic pulp material is pre-treated prior to homogenization by shortening chains of cellulose polymers by cleavage of cellulose chains.

### Claim 20 (depends on 19)

The method according to claim 19, wherein the shortening of the chains of cellulose polymers is performed at least partly by wet grinding in alkali solution.

### Claim 21 (depends on 19)

The method according to claim 19, wherein the shortening of the chains of cellulose polymers is performed at least partly by a method selected among: hydrolysis with sulfuric acid, steam explosion treatment, hydrothermal or treatment.

### Claim 22 (depends on 1)

The method according to claim 1, wherein the alkali solution comprises sodium hydroxide in a concentration range of 7-8 wt % calculated on a total weight of the spinning dope composition.

### Claim 23 (depends on 22)

The method according to claim 22, wherein the concentration of sodium hydroxide is in a range of 7.2-7.8 wt % calculated on the total weight of the spinning dope composition.

### Claim 24 (depends on 1)

The method according to claim 1, wherein a concentration of the cellulosic pulp material is in a range of 5-12 wt % calculated on a total weight of the spinning dope composition.

### Claim 25 (depends on 1)

The method according to claim 1, wherein an additive for gelation prevention is added so that the additive is present during the homogenization.

### Claim 26 (depends on 25)

The method according to claim 25, wherein the additive for gelation prevention is ZnO added in a concentration range of 0.5-1.4 wt % calculated on a total weight of the spinning dope composition.

### Claim 27 (depends on 1)

The method according to claim 1, wherein the method involving homogenization and dissolution is performed continuously.

### Claim 28 (depends on 1)

The method according to claim 1, wherein the dissolution is finalized by passing the cellulosic material in the alkali solution through a mechanical working step in which high shear forces are applied to increase a temperature of the spinning dope composition to a point within a range of from 0 to 30° C.

### Claim 29 (depends on 1)

The method according to claim 1, said method also involving a subsequent treatment of the spinning dope composition in a coagulation bath.

### Claim 30 (depends on 1)

The method according to claim 1, wherein the homogenization is performed according to a plug flow principle and the dissolution is performed according to a continuous stirred tank reactor principle.

### Claim 31 (depends on 4)

The method according to claim 4, wherein the homogenization is performed during a time of less than 60 s.

### Claim 32 (depends on 1)

The method according to claim 1, wherein the power density supplied to agitators used in the homogenization is at least a factor 5 higher than the power density supplied to agitators used in the dissolution.

### Claim 33 (depends on 1)

The method according to claim 1, wherein a time for performing the dissolution is at least a factor 5 longer than a time for performing the homogenization.

### Claim 34 (depends on 5)

The method according to claim 5, wherein the dissolution is performed during a time of 5-60 minutes.

### Claim 35 (depends on 25)

The method according to claim 25, wherein said additive is urea or comprising zinc.

### Claim 36 (depends on 29)

The method according to claim 29, wherein said coagulation bath comprises sodium carbonate or sodium sulfate.