Process for producing microcellulose

Patent metadata

Field	Value
Publication number	US-10358504-B2
Application number	US-201113697726-A
Country	US
Kind code	B2
Filing date	Jun 6, 2011
Priority date	Jun 7, 2010
Publication date	Jul 23, 2019
Grant date	Jul 23, 2019

Abstract

The present invention relates to a process for producing microcellulose comprising subjecting fibrous cellulosic material to acid hydrolysis at a temperature from 10° C. to less than 140° C. and at a consistency of at least 8% on dry weight of the cellulose, wherein the amount of added acid is from 0.2 to 2%, preferably from 0.3 to 1.9%, more preferably from 0.5 to 1.5% on dry weight of the cellulose.

First claim

The invention claimed is:

1. A process for producing microcellulose comprising:
subjecting fibrous cellulosic material having fibre length of 0.2-5 mm, lignin content of 5% or less, and hemicellulose content from 3 to 15% by weight to acid hydrolysis at a temperature from 110° C. to less than 140° C. and at a consistency of at least 8% on dry weight of the fibrous cellulosic material,
wherein the amount of added acid is from 0.5 to 1.5% on dry weight of the fibrous cellulosic material,
wherein the acid hydrolysis is carried in a reactor comprising a mixer,
wherein the produced microcellulose has an average size of 30-100 μm,
wherein the produced microcellulose is obtained without a subsequent mechanical treatment step; and
wherein a yield of the microcellulose is at least 90%.

2. The process according to claim 1 , wherein the added acid comprises a mineral acid.

3. The process according to claim 1 , wherein a compression ratio of the reactor is below 1.5:1.

4. The process according to claim 1 , wherein the temperature is between 110 and 135° C.

5. The process according to claim 1 , wherein the consistency of the fibrous cellulosic material is from 8 to 50%.

6. The process according to claim 1 , wherein the acid hydrolysis time is from 5 to 180 minutes.

7. The process according to claim 1 , wherein the fibrous cellulosic material and the added acid are mixed with each other.

8. The process according to claim 1 , wherein the obtained microcellulose is neutralized or the microcellulose is separated from a hydrolysate, the separated microcellulose is optionally washed and the separated or washed microcellulose is neutralized, or the separated hydrolysate is neutralized.

9. The process according to claim 1 , wherein the fibrous cellulosic material is derived from wood plant material.

10. The process according to claim 1 , wherein the fibrous cellulosic material comprises bleached or unbleached chemical pulp.

11. The process according to claim 1 , wherein the fibrous cellulosic material is derived from non-wood plant material.

12. The process according to claim 1 , wherein the fibrous cellulosic material, has a lignin content of below a kappa number of 40.

13. The process according to claim 1 , wherein the added acid comprises at least one of sulphuric acid, hydrochloric acid or nitric acid.

14. The process according to claim 1 , wherein a compression ratio of the reactor is below 1.2:1.

15. The process according to claim 1 , wherein the temperature is between 115 and 135° C.

16. The process according to claim 1 , wherein the consistency of the fibrous cellulosic material is from 15 to 50% on dry weight of the fibrous cellulosic material.

17. The process according to claim 1 , wherein the consistency of the fibrous cellulosic material is from 20 to 50% on dry weight of the fibrous cellulosic material.

18. The process according to claim 1 , wherein the consistency of the fibrous cellulosic material is from 25 to 45% on dry weight of the fibrous cellulosic material.

19. The process according to claim 1 , wherein the acid hydrolysis time is from 15 to 150 minutes.

20. The process according to claim 1 , wherein the fibrous cellulosic material is derived from at least one of a softwood or hardwood.

21. The process according to claim 1 , wherein the fibrous cellulosic material comprises at least one of: kraft pulp, soda-AQ pulp, sulfite pulp, neutral sulfite pulp, acid sulfite pulp or organosolv pulp.

22. The process according to claim 1 , wherein the fibrous cellulosic material is derived from at least one of: cotton, grass, bagasse, straws of grain crops, flax, hemp, sisal, abaca or bamboo.

23. The process according to claim 1 , wherein the fibrous cellulosic material has a lignin content of below a kappa number of 30.

24. The process according to claim 1 , wherein the fibrous cellulosic material has a lignin content of below a kappa number of 10.

25. The process according to claim 1 , wherein a yield of the microcellulose is at least 95%.

26. The process according to claim 1 , wherein at least 90% by volume of the produced microcellulose has a size below 250 μm.

27. The process according to claim 1 , wherein the hydrolysis takes place in a continuous bleaching reactor.

28. The process according to claim 1 , wherein mechanical energy input during the hydrolysis is 1-5 kWh per dry ton cellulose.

29. The process according to claim 1 , wherein mechanical energy input during the hydrolysis is at most 10 kWh per dry ton cellulose.

30. The process according to claim 1 , wherein mechanical energy input during the hydrolysis is at most 20 kWh per dry ton cellulose.

Assignees

• Karppi Asko
• Vuorenpalo Veli Matti
• Robertsen Leif
• Parviainen Kari
• Dahl Olli
• Vanhatalo Kari
• Kemira Oyj

Inventors

• Karppi Asko
• Vuorenpalo Veli-Matti
• Robertsen Leif
• Parviainen Kari
• Dahl Olli
• Vanhatalo Kari

Classifications

• C08B15/02 Primary

  Oxycellulose; Hydrocellulose; {Cellulosehydrate, e.g. microcrystalline cellulose} · CPC title

• D21C9/00 Primary

  After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters {; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere (polysaccharides, derivatives thereof C08B; paper-making D21B - D21H)} · CPC title