Process for the production of nano-fibrillar cellulose gels
The present invention relates to a process for the production of nano-fibrillar cellulose gels by providing cellulose fibers and at least one filler and/or pigment; combining the cellulose fibers and the at least one filler and/or pigment; and fibrillating the cellulose fibers in the presence of the at least one filler and/or pigment until a gel is formed, as well as the nano-fibrillar cellulose gel obtained by this process and uses thereof.
1. A process for the production of a nano-fibrillar cellulose gel comprising the steps of:
(a) providing cellulose fibres;
(b) providing a filler;
(c) combining the cellulose fibres of step (a) and the filler of step (b); and
(d) fibrillating the cellulose fibres and the filler from step (c) until a nano-fibrillar cellulose gel is formed,
wherein the filler is calcium carbonate, and wherein in step (d) the weight ratio of fibres to filler on a dry weight basis is from 1:33 to 10:1.
2. The process according to claim 1 , wherein the Brookfield viscosity of the nano-fibrillar cellulose gel formed in step (d) is lower than the Brookfield viscosity of a corresponding nano-fibrillar cellulose suspension having been fibrillated in the absence of the filler.
3. The process according to claim 1 , wherein the cellulose fibres in step (a) are eucalyptus pulp, spruce pulp, pine pulp, beech pulp, hemp pulp, cotton pulp, or any mixture thereof.
4. The process according to claim 1 , wherein the cellulose fibres in step (a) are provided in the form of a suspension.
5. The process according to claim 1 , wherein the cellulose fibres in step (a) are provided in the form of a suspension at a solids content of from 0.2 to 35 wt-%.
6. The process according to claim 1 , wherein the cellulose fibres in step (a) are provided in the form of a suspension at a solids content of from 0.25 to 10 wt-%.
7. The process according to claim 1 , wherein the cellulose fibres in step (a) are provided in the form of a suspension at a solids content of from 0.5 to 5 wt-%.
8. The process according to claim 1 , wherein the cellulose fibres in step (a) are provided in the form of a suspension at a solids content of from 1 to 4 wt-%.
9. The process according to claim 1 , wherein the cellulose fibres in step (a) are provided in the form of a suspension at a solids content of from 1.3 to 3 wt-%.
10. The process according to claim 1 , wherein the filler and/or pigment in step (b) is precipitated calcium carbonate.
11. The process according to claim 1 , wherein the filler in step (b) is precipitated calcium carbonate having a vateritic, a calcitic or an aragonitic crystal structure.
12. The process according to claim 1 , wherein the filler in step (b) is ultrafine discrete prismatic, scalenohedral or rhombohedral precipitated calcium carbonate.
13. The process according to claim 1 , wherein the filler in step (b) is natural ground calcium carbonate.
14. The process according to claim 1 , wherein the filler in step (b) is natural ground calcium carbonate selected from marble, limestone and/or chalk.
15. The process according to claim 1 , wherein the filler in step (b) is in the form of particles having a medium particle size of from 0.01 to 15 μm.
16. The process according to claim 1 , wherein the filler in step (b) is in the form of particles having a medium particle size of from 0.1 to 10 μm.
17. The process according to claim 1 , wherein the filler in step (b) is in the form of particles having a medium particle size of from 0.3 to 5 μm.
18. The process according to claim 1 , wherein the filler in step (b) is in the form of particles having a medium particle size of from 0.5 to 4 μm.
19. The process according to claim 1 , wherein the filler in step (b) comprises a dispersing agent.
20. The process according to claim 19 , wherein the dispersing agent is selected from homopolymers or copolymers of polycarboxylic acids and/or their salts or esters, acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, acryl amide or acrylic esters, or mixtures thereof alkali polyphosphates, phosphonic-, citric- and tartaric acids, salts or esters thereof or mixtures thereof.
21. The process according to claim 1 , wherein in step (d) the weight ratio of fibres to filler on a dry weight basis is from 1:10 to 7:1.
22. The process according to claim 1 , wherein in step (d) the weight ratio of fibres to filler on a dry weight basis is from 1:5 to 5:1.
23. The process according to claim 1 , wherein in step (d) the weight ratio of fibres to filler on a dry weight basis is from 1:3 to 3:1.
24. The process according to claim 1 , wherein in step (d) the weight ratio of fibres to filler on a dry weight basis is from 1:2 to 2:1.
25. The process according to claim 1 , wherein in step (d) the weight ratio of fibres to filler on a dry weight basis is from 1:1.5 to 1.5:1.
26. The process according to claim 1 , wherein the fibrillating in step (d) is carried out by a homogenizer or an ultra fine friction grinder.
27. A process for the production of a nano-fibrillar cellulose gel comprising the steps of:
(a) providing cellulose fibres;
(b) providing a filler;
(c) combining the cellulose fibres of step (a) and the filler of step (b); and
(d) fibrillating the cellulose fibres and the filler from step (c) until a nano-fibrillar cellulose gel is formed,
wherein the filler comprises calcium carbonate and one or more of dolomite, talc, bentonite, clay, magnesite, satin white, sepiolite, huntite, diatomite, and a silicate, and wherein in step (d) the weight ratio of fibres to filler on a dry weight basis is from 1:33 to 10:1.