EP1082348A1 - Verfahren zur herstellung einer hochreinen chemikalienfreien mikrokristallinen zellulose aus einer chemisch hergestellten zellulose - Google Patents

Verfahren zur herstellung einer hochreinen chemikalienfreien mikrokristallinen zellulose aus einer chemisch hergestellten zellulose

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Publication number
EP1082348A1
EP1082348A1 EP98921305A EP98921305A EP1082348A1 EP 1082348 A1 EP1082348 A1 EP 1082348A1 EP 98921305 A EP98921305 A EP 98921305A EP 98921305 A EP98921305 A EP 98921305A EP 1082348 A1 EP1082348 A1 EP 1082348A1
Authority
EP
European Patent Office
Prior art keywords
cellulose
microcrystalline cellulose
pulp
process according
bleached
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP98921305A
Other languages
English (en)
French (fr)
Inventor
Paul Jollez
Esteban Chornet
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kemestrie Inc
Original Assignee
Kemestrie Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kemestrie Inc filed Critical Kemestrie Inc
Publication of EP1082348A1 publication Critical patent/EP1082348A1/de
Withdrawn legal-status Critical Current

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Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
    • D21C9/00—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
    • D21C9/001—Modification of pulp properties
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
    • D21C9/00—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
    • D21C9/001—Modification of pulp properties
    • D21C9/007—Modification of pulp properties by mechanical or physical means

Definitions

  • the present invention relates to a process for preparing high purity chemical-free microcrystalline cellulose having a low polymerization degree (DP) from a chemically produced cellulose.
  • DP polymerization degree
  • Microcrystalline cellulose is obtained by depolymerization of cellulosic fibres down to their constitutive microcrystals .
  • Such a depolymerized cellulose is also known as level-off degree of polymerization cellulose (LODP) .
  • the LODP accounts for the fact that cellulosic fibres are constituted of fibrils held together by significant amounts of disordered amorphous cellulose.
  • the fibrils are mainly formed of highly ordered cellulose crystals. The latter are held together by adhesion and by small amounts only of amorphous cellulose in between the crystals.
  • microcrystalline cellulose The preparation of microcrystalline cellulose involves two very- different steps:
  • cellulose fibres is derived from conventional processes using sulfur chemicals, such as S0 2 (sulfite process) , Ne ⁇ S (Kraft process) , and sulfuric acid (ethanol pulping process, or Allcell) .
  • sulfur chemicals such as S0 2 (sulfite process) , Ne ⁇ S (Kraft process) , and sulfuric acid (ethanol pulping process, or Allcell) .
  • the depolymerization of cellulose fibres to yield microcrystalline cellulose via an acid hydrolysis process uses mineral acids (HCl and H 2 S04 being common acids) .
  • Canadien patent No.2,137,890 teaches the conversion of cellulose fibres (derived from conventional pulping processes) into microcrystalline cellulose by using benign reagents, namely 0 2 and C0 2 . More particularly, this patent teaches that low degrees of polymerization, DP, may be obtained by a high pressure treatment of aqueous suspensions of cellulose with 0 2 and C0 2 within autoclaves operated in batch mode. The treated product is subjected to centrifugal washing and spray drying to yield microcrystalline cellulose with a DP of about 300.
  • Canadian patent No. 2,139,400 discloses a process wherein a fibrous cellulose 2-10 wt% suspension is subjected to repeated passages through a high shear zone (two confronting surfaces, one fixed and the other having a rotational movement such as a double disk refiner) at temperatures not greater than 2O0°F. the obtained product is a cellulose having a high retention of water (about 350%) . This cellulose is called "microdenominated cellulose" .
  • Canadian patents No. 1,198,703 discloses a process for the simultaneous production of LODP microcrystalline cellulose and glucose by carrying out in a sequential manner using hardwoods and annual plants (such as straw and bagasse) as starting material.
  • the separation of the hemicellulose, lignin and cellulose is accomplished via steam treatment (which liberates a significant fraction of the hemicelluloses) , delignification (with benign organic solvents or alkaline solutions) , and removal of residual hemicellulose from cellulose by an alkali treatment.
  • the cellulose thus produced is soaked/impregnated with either HCl, H 2 S0 4 or SC 2 , and introduced into a reactor where saturated steam is added to reach 185°-240°C in less than 60 seconds.
  • the treated material is withdrawn (i.e. expelled) from the reactor through a die by opening a valve.
  • the expelled cellulosic solids are adiabatically quenched to 100°C in a fraction of a second.
  • the product that is so obtained consist of disegregated cellulose fibrils ( ⁇ 20-50um in diameter and 1-2 mm in length) and glucose presumably produced from the hydrolysis of amorphous cellulose.
  • microcrystalline cellulose which would use chemically produced cellulose such as a premanufactured specialty pulp as the starting material but would avoid the use of Cl- or S- containing acid reagents.
  • the Applicant has already proposed a process for producing chemical free cellulose which in turn may be used for producing microcrystalline cellulose.
  • any suitable raw material such as softwoods, hardwoods, kenaf, bagasse and straws may be used as starting material.
  • the selected starting material is in the form of shavings, residues or sawdust are first subjected to heating under water vapour pressure for a certain period of time. Then, a violent depressurization is created thereby allowing an instant vaporization of the water from the wood which in turn causes the defibration of the wood matrix.
  • the defibrated wood is then forwarded into a refiner and is subsequently soaked in water to wash away excess of hemicellulose.
  • the lignocellulosic material obtained is then subjected to alkaline or alcohol extraction of the lignin.
  • the latter can be further converted to phenolic products which can be used in the manufacture of adhesives for wood panels, or as raw material for pharmaceutical and nutritional products.
  • a purification step is then carried out for the purpose of concentrating and recovering the "good" fibres .
  • the cellulose fibres so obtained are subjected to a complexation step. This step is necessary to eliminate the presence of ions that could interfere with the next step which is the bleaching of the cellulose.
  • the prior process comprises the steps of:
  • the Applicant has now found a way to produce a high purity chemical free microcrystalline cellulose having a low polymerization degree by using a chemically produced cellulose.
  • microcrystalline cellulose having a low degree of polymerization DP
  • chemically produced cellulose kraft, sulfite
  • the object of the present invention is to provide a process for preparing microcrystalline cellulose by using as a starting material, a chemically produced cellulose which may be in the form of a premanufactured specialty pulp.
  • This process comprises the steps of : a) preparing a pulp by repulping, filtration and trituration of the chemicallly produced cellulose; b) subjecting the pulp obtained in step a) to a steam explosion treatment in order to obtain a microcrystalline cellulose; c) filtering and washing the microcrystalline cellulose; d) bleaching the micrcrystalline cellulose obtained in step c) to obtain a bleached microcrystalline cellulose; and e) filtering and washing the bleached microcrystalline cellulose of step d) to obtain the high purity chemical free microcrystalline cellulose.
  • the process is characterized in that at the end of the steam explosion treatment of step b) , a shearing force is applied onto the pulp.
  • the process of the invention comprises a bleaching step (d) where the microcrystalline cellulose is bleached by using benign chemicals such as caustic and hydrogen peroxide.
  • benign chemicals such as caustic and hydrogen peroxide.
  • the process of the present invention allows the production of microcrystalline cellulose having a DP comprised between 150 and 260, a whiteness higher than 80 and a cristallinity index of about 83% to 87%.
  • a premanufactured pulp such as a specialty pulp, which is a bleached cellulose from angyosperm or gymnosperm obtained from kraft, bisulfite chemical processes or any conventional pulping processes, is used as the starting material.
  • Softwoods provide microcrystalline cellulose with a level of DP (LODP) >200, whereas hardwoods and straws yield microcrystalline cellulose having level of DP (LODP) ⁇ 200.
  • the degree of polymerisation can be tailored and optimized that is reduced by subsequent aqueous/steam treatments. However, this will cause a reduction in the final yield of the microcrystalline cellulose.
  • the starting material When carrying out the process of the invention, the starting material must not be in a condensed state so that it is easily transported. It must contain a residual humidity varying from 35 to 65%. Hence, if the starting material is a premanufactured pulp, it must be repulped in order to increase its humidity and to render it in a less condensed state. This in turn will increase its reactivity.
  • the cellulose having a proper level of humidity is subjected in a reactor to a steam explosion treatment in a continuous or discontinuous batch mode.
  • the steam explosion treatment is carried by pressurization of the reactor. This is done by injecting steam in the reactor.
  • the various conditions such as temperature, pressure and residence time are perfectly determined and controlled so that it is possible to develop a mathematical model, referred to as the "severity" factor, R 0 , for determining the final quality of the treated cellulose.
  • “Severity” stands for a hydrolysis control parameter represented by the symbol R 0 and expressed by the mathematical formula which combines two variables, namely the time of heating and the temperature or vapour pressure.
  • R 0 t x e T-100/14.75 t is the time of heating in minutes and T is the temperature in Celsius.
  • a shearing force is applied at the end of the steam explosion treatment and the treated material is subjected to filtration.
  • the shearing force is the result of the combined effect of a violent vaporization induced by an instant depressurization and a sudden flow of the pulp out of the reactor through a discharge valve.
  • the cellulose is simultaneously washed in order to prepare the pulp for bleaching.
  • an important aspect of the present invention lies in that at the end of the steam explosion treatment, a shearing force is applied on the treated pulp.
  • the final bleaching using sodium hypochlorite at 40°C, pH > 9 during 1 or 2 hours or hydrogen peroxide is carried out at a pH comprised between 10 and 11, at a temperature of 60°C or 110° to 120°C under nitrogen or oxygen pressure varying from 60 to 120 psi, and in the presence of magnesium sulfate and sodium silicate.
  • the method to prepare this type of pulp comprises a step of steam explosion which could be carried out in a continous or discontinuous batch mode.
  • the pressure, temperature and contact time are perfectly determined and controlled, since they have been modeled for each type and form of biomass and each type and size of reactor.
  • the poplar chips (6 mm of thickness and 1 to 2 inches in width) must contain a humidity level of between 35% and 65% calculated as base humidity.
  • a 6 litre reactor is charged with the wood and is supplied by steam.
  • the reactor is maintained at a pressure of 380 psi for 3 minutes before carrying out instant depressurization.
  • the resulting pulp from the cyclone is refined at a pulp consistency of 2% for 90 seconds at 18000 rpm in a Waring Blender Commercial Model 38 BL.19 with water at 60°C or up, so as to eliminate the hemicellulose liberated during cooking.
  • the lignocellulose obtained is mixed in a solution of sodium hydroxide at 22 grams per litre so as to acheive a pulp consistency of 10%.
  • the treatment is carried out at 160 °C for 90 minutes.
  • the partially delignified cellulose After washing, the partially delignified cellulose has a kappa index between 6 and 8. A purification step of the pulp allows to separate fines and other impurities so to obtain a very low kappa index which is between 3 and 5. The cellulose is then bleached either by the classical sequences of bleaching CepHD:
  • the bleached cellulose is obtained with an output of 35% on the original chips (output calculated from the dry bases) and embodies the following characteristics:
  • This high purity cellulose may be used as a soluble pulp in the production of viscose, cellulose acetate and microcrystalline cellulose.
  • the bleached cellulose pulp obtained herein above is transformed into microcrystalline cellulose by a process which is an object of the present invention.
  • the soluble pulp is brought to a residual humidity comprised between 35% and 65%, preferably 50% before being treated with steam at 350 psi for 8 minutes, washed and bleached with hydrogen peroxide at pH 10,5 during 60 minutes at 60°C and preferably at 120 °C under nitrogen or oxygen pressure.
  • microcrystalline cellulose has the following characteristics : DP: 170 Crystallinity index (RX) : 87%
  • the cellulose of this example was prepared from selected sugarmaple sawdust.
  • the pulping process is similar to the one described in example 1, wherein the heating step is carried out at a pressure of 350 psi for 4 minutes.
  • the purification step is maintained so as to have a pulp consistency of 2%.
  • the lignocellulose is treated at a pulp consistency of 12% in a sodium hydroxide solution (28g/l) at 160°C for 90 minutes.
  • the lignin is solubilized in the form of sodium lignate.
  • the cellulose so obtained has a kappa index of 10.
  • a chelating agent is added to the treatment so as to prepare the bleaching with hydrogen peroxide (2% from dry base) at pH 10,5 in a pulp consistency of 12%. After washing and filtration, the cellulose comprises the following characteristics:
  • This cellulose may be used as a food fibre due to its high purity and its method of production which do not require any use of chlorinated and/or sulphurated products. This cellulose may also be used as a starting material for the application of specialty pulp production, viscose, cellulose acetate, etc.
  • the cellulose obtained herein above is subjected to a reactor for the steam explosion treatment. This treatment is carried out at 320 psi for 8 minutes. After this treatment, an instant depressurization is carried out in the reactor. A bleaching step is carried out and the resulting microcrystalline cellulose embodies the following characteristics: DP : 182 Crystallinity index (RX) : 85 Density: 0, 28g/cm3 Ash: 0, 10%
  • the treatment that was applied for a pulp having a high DP was 16 minutes under 320 psi.
  • the obtained cellulose was sieved on 70 mesh.
  • This cellulose can be bleached at 60°C using 2% of hydrogen peroxide in the presence of magnesium sulfate and sodium silicate at pH 10,5.
  • it is carried out at 40°C for 2 hours with a pulp consistency of 10% and at a pH >9.
  • the output of these operations is 80% on dry cellulose as the starting material .
  • Cellulose Q90* a resinous kraft pulp (20% Jack pine, 80% Black Spruce) having the following characteristics was used as a starting material for the present example.
  • microcrystalline cellulose embodied the following characteristics:

Landscapes

  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Wood Science & Technology (AREA)
  • Mechanical Engineering (AREA)
  • Polysaccharides And Polysaccharide Derivatives (AREA)
  • Paper (AREA)
EP98921305A 1998-05-14 1998-05-14 Verfahren zur herstellung einer hochreinen chemikalienfreien mikrokristallinen zellulose aus einer chemisch hergestellten zellulose Withdrawn EP1082348A1 (de)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/CA1998/000479 WO1999060027A1 (en) 1998-05-14 1998-05-14 Process for preparing a high purity chemical-free microcrystalline cellulose from a chemically produced cellulose

Publications (1)

Publication Number Publication Date
EP1082348A1 true EP1082348A1 (de) 2001-03-14

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP98921305A Withdrawn EP1082348A1 (de) 1998-05-14 1998-05-14 Verfahren zur herstellung einer hochreinen chemikalienfreien mikrokristallinen zellulose aus einer chemisch hergestellten zellulose

Country Status (4)

Country Link
EP (1) EP1082348A1 (de)
AU (1) AU7421698A (de)
CA (1) CA2313261C (de)
WO (1) WO1999060027A1 (de)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA2427397A1 (en) 2000-11-03 2002-05-10 Kemestrie Inc. Process for producing low dp microcrystalline cellulose
KR100376203B1 (ko) * 2000-12-26 2003-03-15 한국에너지기술연구원 황산 및 황산염 첨가물을 이용한 아임계 및 초임계수내에서의 셀룰로오스의 연속분해방법
CA2383279A1 (fr) * 2002-05-06 2003-11-06 Sylvain Cloutier Reacteur
JP2009532483A (ja) 2006-04-05 2009-09-10 ウッドランド バイオフュールズ インコーポレイテッド 合成ガスを介してバイオマスをエタノールに変換するための方法
FI20126168A7 (fi) * 2012-11-07 2014-05-08 Metsae Fibre Oy Menetelmä sellupitoisten kuitujen avaamiseksi

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4461648A (en) * 1980-07-11 1984-07-24 Patrick Foody Method for increasing the accessibility of cellulose in lignocellulosic materials, particularly hardwoods agricultural residues and the like
CA1198703A (en) * 1984-08-02 1985-12-31 Edward A. De Long Method of producing level off d p microcrystalline cellulose and glucose from lignocellulosic material
WO1992014760A1 (en) * 1991-02-21 1992-09-03 Genencor International, Inc. Crystalline cellulose production
DE4342442C2 (de) * 1993-12-13 1996-11-21 Akzo Nobel Nv Verfahren zur Herstellung von Level-off DP Cellulose (LODP Cellulose) und ihre Desaggregierung zu mikrokristalliner Cellulose

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9960027A1 *

Also Published As

Publication number Publication date
WO1999060027A1 (en) 1999-11-25
CA2313261A1 (en) 1999-11-25
CA2313261C (en) 2002-02-12
AU7421698A (en) 1999-12-06

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