[go: up one dir, main page]

WO2002042334A1 - Procede de purification d'ethers d'alkylcellulose non cationiques - Google Patents

Procede de purification d'ethers d'alkylcellulose non cationiques

Info

Publication number
WO2002042334A1
WO2002042334A1 PCT/EP2001/013389 EP0113389W WO0242334A1 WO 2002042334 A1 WO2002042334 A1 WO 2002042334A1 EP 0113389 W EP0113389 W EP 0113389W WO 0242334 A1 WO0242334 A1 WO 0242334A1
Authority
WO
WIPO (PCT)
Prior art keywords
solvent
alkyl cellulose
cellulose ether
mixture
solvent mixture
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.)
Ceased
Application number
PCT/EP2001/013389
Other languages
German (de)
English (en)
Inventor
Alf Hammes
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.)
Clariant Produkte Deutschland GmbH
Original Assignee
Clariant GmbH
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 Clariant GmbH filed Critical Clariant GmbH
Publication of WO2002042334A1 publication Critical patent/WO2002042334A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
    • C08B11/00—Preparation of cellulose ethers
    • C08B11/20—Post-etherification treatments of chemical or physical type, e.g. mixed etherification in two steps, including purification

Definitions

  • the present invention relates to a process for the purification of nonionic alkyl cellulose ethers as part of their workup, which leads to products via a combination of a solution of the alkyl cellulose ethers in water or water / solvent mixtures, removal of insoluble residues and subsequent removal of the alkyl cellulose ethers from the solvent or solvent mixture come off without residue.
  • cellulose ethers such as methyl cellulose, methyl hydroxyethyl cellulose, methyl hydroxypropyl cellulose or
  • Ethylhydroxyethylcellulose the starting material, the pulp
  • the resulting voluminous pulp powder is converted into "alkali cellulose" by adding base, such as NaOH, KOH, LiOH or ammonium hydroxides, in solid or liquid form. This is followed, with or without isolation of the alkali cellulose, by a single-stage or multi-stage, continuous or discontinuous etherification using the appropriate reagents.
  • the resulting cellulose ethers are purified in a known manner from reaction by-products, dried and ground with water or suitable solvent mixtures and optionally mixed with other components.
  • Solutions of alkyl cellulose ethers produced in this way generally give insoluble residues of between 0.1 and 20% by weight, based on the amount of alkyl cellulose ether used.
  • the absolute residue level is significantly influenced by the type of etherification, the amount of etherification and the uniformity of the substituent distribution along the anhydroglycose backbone.
  • the insoluble residues mainly consist of cellulose fibers and / or swelling bodies.
  • the pulp fibers are low-etherified constituents of the pulp, the fiber structure of which is practically completely preserved and whose hydroxyl groups are not accessible to the solvent, generally water, since they are integrated into a dense network via solid intra- and / or intermolecular hydrogen bonds are. Swelling bodies occur with sufficient but uneven etherification. Although the polar groups of the cellulose ether are accessible in a wide range for the formation of a hydration shell, some areas of the polymer chains are substituted so low or the fibrillar character is still preserved, so that complete solvation of the polymer molecules is prevented. Swell body residues therefore increasingly occur when the average degree of polymerization of the pulp used is increased.
  • Essential criteria of the product quality of alkyl cellulose ethers are, among other things, the residue level in aqueous solution and the filter residue that usually correlates with it.
  • the product quality in the production of the alkyl cellulose ethers can be influenced in particular by the process of disintegrating the pulp by means of a strong base, the so-called alkalization. Great importance must be attached to adequate homogenization of the heterogeneous system.
  • the polymer chains of the pulp used which are closely linked via hydrogen bonds, are at least partially dissolved by the action of the base and the fibrillar structure is expanded so that the hydroxyl groups of the anhydroglycose backbone are made accessible to the reagents with which they are to be reacted and activated by deprotonation , Depending on their origin, type and pretreatment, pulps have different degrees of crystallinity.
  • the degree of crystallinity describes the relationship between crystalline and amorphous areas of the pulp and can be used as an approximate measure for an estimate of how easily a pulp can be broken down.
  • the hydroxyl groups of Linters pulps which generally have a high degree of crystallinity, are difficult to access for the alkali. Sufficient digestion takes a comparatively long time or a large amount of alkali compared to the digestion of an amorphous wood pulp.
  • the uniform distribution of the substituents can be influenced to a certain extent via the reaction conditions, a suitable reaction procedure and the type and amount of mixed etherification. Regardless of the targeted influencing of these parameters, however, it is practically impossible in the production of alkyl cellulose ethers according to the prior art to produce products which dissolve without residues. A small residue remains.
  • Nonionic cellulose ethers with a flocculation point below the boiling point of water are usually cleaned of reaction by-products and salts by treating them with hot water or water-solvent mixtures (see e.g. Ullmann's Encyclopedia of
  • WO-A-98/31710 describes a process for the production of finely divided polysaccharide derivatives in which the cellulose ethers are swollen or dissolved in a sufficient amount of solvent or solvent mixture, so that superordinate structures are largely eliminated.
  • the pretreated material is then converted into a finely divided powder using a mill-drying device or by dispersing it in a non-solvent surrounding medium.
  • JP-A-10/287701 cellulose ethers are mixed with water in order to obtain emulsified liquids of low viscosity, which are then spray-dried. The result is fine cellulose ether powder with a narrow particle size distribution.
  • a disadvantage of the known processes is that the cellulose ethers are not separated from insoluble, low etherification components similar to cellulose fibers. The result is products whose solutions have residues.
  • the object of the present invention was therefore to develop a process for the purification of nonionic alkyl cellulose ethers which provides solutions which are virtually free of residues.
  • the object of the invention is achieved by a process for the purification of nonionic alkyl cellulose ethers, which is characterized in that the nonionic alkyl cellulose ether is dissolved in a suitable solvent or solvent mixture, then the residues are removed and then the alkyl cellulose ether is separated from the solvent or solvent mixture. This results in solid alkyl cellulose ethers, which dissolve without residue.
  • the height of the filter residue can be used as a criterion for the absence of residues. This should be less than 0.1% by weight, preferably less than 0.09% by weight and particularly preferably less than 0.08% by weight, based on the dry cellulose ether, corrected for the moisture.
  • the cellulose ethers purified by the process according to the invention have a filter residue which is reduced by at least 60% compared to the cellulose ethers cleaned according to the prior art.
  • Preferred nonionic alkyl cellulose ethers are methyl cellulose, methyl hydroxyethyl cellulose, methyl hydroxypropyl cellulose, ethyl hydroxyethyl cellulose and ethyl hydroxypropyl cellulose.
  • Water is particularly preferred as the solvent.
  • suitable means a ratio that is capable of dissolving the corresponding alkyl cellulose ether.
  • a solvent mixture which contains a maximum of 80% methanol or ethanol and at least 20% water is preferred.
  • Solvent mixtures of methanol with dichloromethane, chloroform, carbon tetrachloride, dichloroethane, trichloroethane or chlorobenzene can also be used in suitable proportions. Solvent mixtures containing 20 to 60% methanol are preferred here. Solvent mixtures of ethanol with dichloromethane, chloroform, carbon tetrachloride, dichloroethane, trichloroethane or chlorobenzene can also be used. Solvent mixtures containing 25 to 55% ethanol are preferred here.
  • the weight ratio of solvent or solvent mixture to nonionic alkyl cellulose ether is chosen depending on the average degree of polymerization of the alkyl cellulose ether so that the viscosity of the resulting solution, from which the residues are to be separated, does not exceed 20,000 mPas, measured according to Höppler.
  • the viscosity of the solution should preferably be below 10000 mPas and particularly preferably below 5000 mPas.
  • the separation of the insoluble residues contained in the solvent or solvent mixture can be carried out using common separation processes such as Filtration, centrifugation or decanting take place.
  • the subsequent separation of the alkyl cellulose ether from the solvent or solvent mixture can be carried out, for example, by heating the solution to a temperature above the flocculation point of the cellulose ether with flocculation and subsequent separation from the solvent or solvent mixture using suitable units, e.g. Filters, centrifuges or decanters are made.
  • suitable units e.g. Filters, centrifuges or decanters are made.
  • the solvent or solvent mixture can be separated from the cellulose ether by at least partial distillation.
  • the separation of the nonionic alkyl cellulose ethers in particular the flocculation from heated or boiling, aqueous solution, can be carried out particularly well in the presence of special salts.
  • the presence of the salts causes an agglomeration of the finely divided precipitation particles to form larger groups that are easier to separate. If these salts are completely absent, a very finely divided flocculation product precipitates, the separation of which is much more difficult.
  • sulfates, carbonates and / or chlorides and particularly preferably sodium sulfate, sodium carbonate and / or sodium chloride are used as flocculation aids and facilitate the precipitation of the alkyl cellulose ether from a heated solution.
  • Flocculation can also be carried out by adjusting the aqueous solutions containing alkyl cellulose ethers to an alkaline pH by means of bases.
  • bases are e.g. Lithium hydroxide, sodium hydroxide, potassium hydroxide and / or ammonia solution. It is also conceivable to add special polyacrylamides or other flocculants.
  • the alkyl cellulose ethers are preferably dissolved in the solvent or solvent mixture as a crude product which is not or only partially purified, as is obtained after the conversion from cellulose to cellulose ether. This means that in particular reaction by-products and salts such as sodium chloride are still present.
  • the salt content of the cellulose ethers is preferably between 0.5 and 300% by weight, and particularly preferably between 1 and 60% by weight, based on the cellulose ether.
  • the salts are removed particularly effectively from the product in the course of the work-up process if polar solvents such as water or water-containing solvent mixtures are used to dissolve the alkyl cellulose ether. Due to their positive temperature coefficient of solubility, the salts remain in solution, while the alkyl cellulose ether is flocculated by coagulation in a hot medium.
  • polar solvents such as water or water-containing solvent mixtures
  • the product produced according to the invention has a morphological structure, which is characterized in that the fiber structure resulting from the fibrillar character of the pulp is completely destroyed.
  • organic solvents or solvent mixtures such as, for example, methanol / water or ethanol / water mixtures
  • the cellulose ether can also be separated from the solvent or solvent mixture by removing the volatile constituents by distillation, leaving the cellulose ether behind.
  • purified cellulose ethers with a residual salt content of less than 5% by weight as the starting products for the separation of the alkyl cellulose ethers from insoluble constituents, since salts can only be removed by additional process steps.
  • the viscosities of the end products are 2.0% aqueous
  • the molar degree of substitution for example with ethylene oxide or propylene oxide (MS (EO), MS (PO)), and the average degree of substitution, for example with methyl chloride (DS), are calculated from the percentage contents determined experimentally using the Zeisel digestion% OC 2 H,% OC3H ⁇ and% OCH3 according to:
  • MS (EO) [% OC 2 H 4 x 3.68] / [100 - (% OCH 3 x 0.452) -% OC 2 H 4 ]
  • MS (PO) [% OC 3 H 6 x 2.79] / [100 - (% OCH 3 x 0.452) -% OC 3 H 6 ]
  • DS [% OCH 3 x 5.226] / [100 - (% OCH 3 x 0.452) -% OC 2 (3 ) H 4 (6) ]
  • the residue level is determined by dissolving 2 to 5 g of alkyl cellulose ether (weight corrected for residual salt content and moisture) in 150 to 500 g of water at 20 ° C.
  • the filter residue is determined using the following method:
  • alkyl cellulose ether (initial weight corrected for residual salt content and moisture) are dissolved in 1000 g of water at 20 ° C. with stirring. It is then filtered through a water jet vacuum using a nylon filter (mesh size: 0.02 mm), the initial weight of which has been determined in advance, and dried at 105 ° C. for 60 minutes. After complete filtration, the residue on the filter is washed with 1000 g of deionized water and then the filter is dried on a watch glass in a drying cabinet at 105 ° C. for 60 minutes. After cooling in the desiccator, the filter is weighed on the analytical balance, the weight difference compared to the pure filter weight is calculated and the percentage residue level, based on the weight of alkyl cellulose ether, is calculated.
  • a wood pulp 1 is combined with propylene oxide and methyl chloride according to a common production process, as described in EP-A-0 117 490
  • the crude product obtained after the reaction and distillation of the solvent contains, in addition to approx. 30% alkyl cellulose ether and reaction by-products, approx. 50% salt (NaCl) and 20% moisture (water and residual solvent).
  • the filter cake is again opened in 5 liters of boiling water and, after 5 to 10 minutes of boiling, separated by renewed filtration through a glass frit.
  • the product thus purified from salt and reaction by-products and solvent residues is dried at 70 ° C. to a residual moisture content of less than 5%.
  • the result is a product which has a solution viscosity of 180 mPas in 2.0% aqueous solution.
  • Example 1b 500 g of the crude product mixture from preparation example 1 are poured into 2.5 liters of boiling water, adjusted to pH 6.5 to 7.5 with 15% hydrochloric acid and, after 5 to 10 minutes of boiling, separated off in a water jet vacuum using a glass frit.
  • the product pre-cleaned in this way consists of approx. 40% alkyl cellulose ether, 5% salt and 55% moisture.
  • 190 g of this pre-cleaned mixture are completely dissolved in one liter of water at 20 ° C., the homogeneous solution is distributed over 4 polypropylene centrifuge tubes and spun in a centrifuge at 8000 rpm for 20 minutes.
  • a wood pulp 2 is converted according to a conventional production process, as described in EP-A-0 117 490, with propylene oxide and methyl chloride to an alkyl cellulose ether with an MS (PO) of 0.74 and a DS of 1.9.
  • the crude product obtained after the reaction and distillation of the solvent contains, in addition to approx. 30% alkyl cellulose ether and reaction by-products, approx. 50% salt (NaCl) and 20% moisture (water and residual solvent).
  • Example 1b It is worked up as described for Example 1b. The result is a product which has a solution viscosity of 480 mPas in 2.0% aqueous solution.
  • Production example 3 A wood pulp 1 is produced according to a common production process, as in the
  • EP-A-0 117 490 described, with ethylene oxide and methyl chloride to one
  • the crude product contains approx. 35% salt (NaCI) and 30% moisture (water and
  • Example 1b It is worked up as described for Example 1b. The result is a product which has a solution viscosity of 220 mPas in 2.0% aqueous solution.
  • the cellulose ether raw product mixture from preparation example 1 is used.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Biochemistry (AREA)
  • Materials Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Polysaccharides And Polysaccharide Derivatives (AREA)

Abstract

La présente invention concerne un procédé de purification d'éthers d'alkylcellulose non cationiques, caractérisé en ce que l'éther d'alkylcellulose non cationique est dissous dans un solvant ou dans un mélange de solvants adapté, les résidus sont retirés, puis l'éther d'alkylcellulose est séparé du solvant ou du mélange de solvants.
PCT/EP2001/013389 2000-11-22 2001-11-20 Procede de purification d'ethers d'alkylcellulose non cationiques Ceased WO2002042334A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE2000157799 DE10057799A1 (de) 2000-11-22 2000-11-22 Verfahren zur Reinigung von nichtionischen Alkylcelluloseethern
DE10057799.7 2000-11-22

Publications (1)

Publication Number Publication Date
WO2002042334A1 true WO2002042334A1 (fr) 2002-05-30

Family

ID=7664157

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2001/013389 Ceased WO2002042334A1 (fr) 2000-11-22 2001-11-20 Procede de purification d'ethers d'alkylcellulose non cationiques

Country Status (2)

Country Link
DE (1) DE10057799A1 (fr)
WO (1) WO2002042334A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1411065A1 (fr) * 2002-10-14 2004-04-21 Lamberti Spa Agents modificateurs de rhéologie pour les produits de construction

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2118664A (en) * 1937-01-07 1938-05-24 Dow Chemical Co Cellulose ether purification
US4404370A (en) * 1980-11-27 1983-09-13 Wolff Walsrode Ag And Bayer Ag Purification of cellulose and starch ethers with counter current washing
WO1998031710A1 (fr) * 1997-01-21 1998-07-23 Wolff Walsrode Ag Procede de preparation de derives de polysaccharide a fines particules

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2118664A (en) * 1937-01-07 1938-05-24 Dow Chemical Co Cellulose ether purification
US4404370A (en) * 1980-11-27 1983-09-13 Wolff Walsrode Ag And Bayer Ag Purification of cellulose and starch ethers with counter current washing
WO1998031710A1 (fr) * 1997-01-21 1998-07-23 Wolff Walsrode Ag Procede de preparation de derives de polysaccharide a fines particules

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1411065A1 (fr) * 2002-10-14 2004-04-21 Lamberti Spa Agents modificateurs de rhéologie pour les produits de construction

Also Published As

Publication number Publication date
DE10057799A1 (de) 2002-05-23

Similar Documents

Publication Publication Date Title
DE1468017C3 (de) Hydroxypropylcellulosen und Verfahren zu deren Hers ellung
DE3712246C2 (fr)
DE69719326T2 (de) Verfahren zur herstellung einer homogenen celluloselösung in n-methylmorpholin-n-oxid
EP0080678B1 (fr) Procédé pour la préparation d'éthers de la cellulose soluble dans l'eau avec le diméthoxyéthane comme agent dispersant
DE69327286T2 (de) Verfahren zur Herstellung eines Fettsäureesters von Cellulose
DE3008413A1 (de) Verfahren zur herstellung von aethylcarboxymethylcellulose
EP0053741B1 (fr) Purification d'éthers de la cellulose et de l'amidon
EP0117490B1 (fr) Procédé pour la préparation d'éthers de la cellulose en présence d'un agent dispersant contenant aussi du diméthoxyéthane
EP0108991B1 (fr) Procédé pour la préparation d'éthers de cellulose à partir de la cellulose activée par l'ammoniaque
DE4439149C9 (de) Verfahren zur Herstellung einer homogenen Celluloselösung
DE4439149C2 (de) Verfahren zur Herstellung einer homogenen Celluloselösung
EP0105231B1 (fr) Procédé pour l'éthérification de la cellulose avec des esters de l'acide monochloracétique
EP1237931A1 (fr) Ethers de cellulose a faible viscosite, pouvant floculer dans l'eau chaude, leur procede de production par depolymerisation et leur utilisation
EP0212625B1 (fr) Procédé de préparation d'éthers de cellulose de faible viscosité
WO2002042334A1 (fr) Procede de purification d'ethers d'alkylcellulose non cationiques
EP0038925B1 (fr) Procédé de préparation d'alcali-cellulose presque sèche
EP1278779B1 (fr) Procede pour la production d'ethers cellulosiques non ioniques, au moins alkyles, pulverulents, solubles dans l'eau et bien mouillables
WO1998021246A1 (fr) Procede de production de derives de cellulose
DE1801553A1 (de) Verfahren zur Herstellung von Carboxymethylcellulose mit glattem,langfliessendem Loesungsverhalten
DE3238278A1 (de) Verfahren zur herstellung von niedrigsubstituierten, gut wasserloeslichen carboxyalkyl-polysaccharid-(misch-)ethern sowie entsprechende polysaccharid-mischether
EP3728331B1 (fr) Dégradation oxydative de l'ether cellulose
DE69529664T2 (de) Pelletierte Granulate aus Zellulose und tertiären Aminoxyden; Verfahren zu deren Herstellung und Verfahren zur Herstellung von Formkörpern daraus
DE1222030B (de) Verfahren zur Herstellung von Methyl-hydroxyalkyl-celluloseaethern
DE2530451A1 (de) Ester von polyhydroxypolymeren und verfahren zu ihrer herstellung
DE3246676A1 (de) Verfahren zur herstellung von wasserloeslicher natriumcarboxymethylcellulose

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): JP KR MX US

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE TR

DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
121 Ep: the epo has been informed by wipo that ep was designated in this application
122 Ep: pct application non-entry in european phase
NENP Non-entry into the national phase

Ref country code: JP

WWW Wipo information: withdrawn in national office

Country of ref document: JP

WA Withdrawal of international application