CA2283980A1 - Method for producing cellulose acetate - Google Patents
Method for producing cellulose acetate Download PDFInfo
- Publication number
- CA2283980A1 CA2283980A1 CA002283980A CA2283980A CA2283980A1 CA 2283980 A1 CA2283980 A1 CA 2283980A1 CA 002283980 A CA002283980 A CA 002283980A CA 2283980 A CA2283980 A CA 2283980A CA 2283980 A1 CA2283980 A1 CA 2283980A1
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- Canada
- Prior art keywords
- cellulose
- base
- process according
- cellulose acetate
- stage
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- 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.)
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
- C08B3/00—Preparation of cellulose esters of organic acids
- C08B3/06—Cellulose acetate, e.g. mono-acetate, di-acetate or tri-acetate
Abstract
The invention relates to a method for producing cellulose acetate with a DS
between 1.5 and 2.9 by reacting cellulose with an acetylation agent. According to said method, the cellulose is reacted with a first acetylation agent using a base catalyst in a first step, to form a cellulose acetate with a DS of less than 1, and then reacted with a second acetylation agent using an acid catalyst in a second step to form a cellulose acetate with a DS of 1.5 to 2.9.
The first and second acetylation agents are preferably acetic anhydride. The cellulose is preferably impregnated with an excess base in the first step, said base then being removed until the quantity of base which is stoichiometrically necessary to form the cellulose acetate with a DS1 is achieved.
between 1.5 and 2.9 by reacting cellulose with an acetylation agent. According to said method, the cellulose is reacted with a first acetylation agent using a base catalyst in a first step, to form a cellulose acetate with a DS of less than 1, and then reacted with a second acetylation agent using an acid catalyst in a second step to form a cellulose acetate with a DS of 1.5 to 2.9.
The first and second acetylation agents are preferably acetic anhydride. The cellulose is preferably impregnated with an excess base in the first step, said base then being removed until the quantity of base which is stoichiometrically necessary to form the cellulose acetate with a DS1 is achieved.
Description
METHOD FOR PRODUCING CELLULOSE ACETATE
The invention relates to a process for the production of cellulose acetate having a DS between 1.5 and 2.9.
Cellulose acetate with a degree of substitution (DS) between 1.5 and 2.9 is an important product for various industrial applications. Degree of substitution DS designates the number of hydroxyl groups which are esteri-fied on average with acetyl groups per anhydroglucose unit of the cellulose.
In the known processes for the production of cellulose acetate with a DS
between 1.5 and 2.9 in a first process stage cellulose is always reacted to triacetate and the cellulose triacetate is subsequently hydrolyzed to the desired degree of substitution. If acetylation is performed with an acetylating agent deficiency or acetylation is prematurely broken off, no homogeneous, partly acetylated product is obtained and instead there is essentially a mixture of cellulose triacetate and unreacted cellulose. The reason for this is the structure of cellulose, which on the one hand contains amorphous fractions and on the other crystalline fractions.
Whereas the amorphous fractions are readily accessible to the acetylating agent, the crystalline fractions are difficultly accessible, which leads to an inhomogeneous reaction sequence. An indicator for a homogeneous substi-tuent distribution in a partly acetylated cellulose acetate is its solu-bility in acetone. For the same average acetyl group content, inhomogen-eous cellulose acetates are insoluble in acetone.
Moreover, in the known technical processes, use is made of a more or less large excess of acetylating agent, generally acetic anhydride, in order to aid the reaction sequence. Both the need to pass through the triacetylated stage and also the necessary use of an acetic anhydride excess in compari-son with the stoichiometrically necessary quantity give rise to an increased acetylating agent consumption, which in the case of 2,5-cellulose acetate can be up to 31%. As for many industrial applications a 2,5-cellulose acetate can be replaced by a cellulose acetate with a DS ~2, 30further acetylating agent savings could result from a process not requiring the detour via cellulose triacetate.
Apart from cellulose, commercial pulps always contain a certain proportion of other wood constituents, such as lignin and in particular hemicelluloses.
The invention relates to a process for the production of cellulose acetate having a DS between 1.5 and 2.9.
Cellulose acetate with a degree of substitution (DS) between 1.5 and 2.9 is an important product for various industrial applications. Degree of substitution DS designates the number of hydroxyl groups which are esteri-fied on average with acetyl groups per anhydroglucose unit of the cellulose.
In the known processes for the production of cellulose acetate with a DS
between 1.5 and 2.9 in a first process stage cellulose is always reacted to triacetate and the cellulose triacetate is subsequently hydrolyzed to the desired degree of substitution. If acetylation is performed with an acetylating agent deficiency or acetylation is prematurely broken off, no homogeneous, partly acetylated product is obtained and instead there is essentially a mixture of cellulose triacetate and unreacted cellulose. The reason for this is the structure of cellulose, which on the one hand contains amorphous fractions and on the other crystalline fractions.
Whereas the amorphous fractions are readily accessible to the acetylating agent, the crystalline fractions are difficultly accessible, which leads to an inhomogeneous reaction sequence. An indicator for a homogeneous substi-tuent distribution in a partly acetylated cellulose acetate is its solu-bility in acetone. For the same average acetyl group content, inhomogen-eous cellulose acetates are insoluble in acetone.
Moreover, in the known technical processes, use is made of a more or less large excess of acetylating agent, generally acetic anhydride, in order to aid the reaction sequence. Both the need to pass through the triacetylated stage and also the necessary use of an acetic anhydride excess in compari-son with the stoichiometrically necessary quantity give rise to an increased acetylating agent consumption, which in the case of 2,5-cellulose acetate can be up to 31%. As for many industrial applications a 2,5-cellulose acetate can be replaced by a cellulose acetate with a DS ~2, 30further acetylating agent savings could result from a process not requiring the detour via cellulose triacetate.
Apart from cellulose, commercial pulps always contain a certain proportion of other wood constituents, such as lignin and in particular hemicelluloses.
Hemicelluloses or their acetylated forms impair both the processing, partic ularly the solubility, filterability and spinability, and the product characteristics of the industrially produced cellulose acetates. Admit-tedly processes are known with the aid of which the influence of hemi-celluloses is largely repressed, but they involve further acetic anhydride consumption. Hemicelluloses are decomposed to monosaccharides and oligo-saccharides and discharged during acetate washing. In addition, these processes (high temperature hydrolysis) are relatively energy-consuming and tedious, involving high investment costs. It is therefore advantageous to carry out the separation of hemicelluloses and other wood constituents, such as lignin and fats, by a stage consuming no acetylating agent.
The commercially available pulps suitable for acetylation belong to the high-quality pulps and contain only relatively little hemicellulose (2 to 3 wt.%). There is a need for a process in which use can be made of less high-quality pulps, i.e. pulps with a higher hemicellulose content. This would represent a considerable cost saving, because pulp prices are rela-tively high and cellulose acetate consists of approximately 60% cellulose.
The problem of the invention is consequently to provide a process for the production of cellulose acetate with a DS between 1.5 and 2.9, which requires the use of smaller acetylating agent quantities than the known processes and in particular requires no detour via cellulose triacetate.
It is intended to supply cellulose acetates with a substantially homogen-eous substituent distribution. The process must also permit the use of less high-quality pulps, in that the admixtures such as hemicelluloses, li ~ - . __,s_~___LS__ ..L_ _..",~.... .,..a AMENDED SHEET
The commercially available pulps suitable for acetylation belong to the high-quality pulps and contain only relatively little hemicellulose (2 to 3 wt.%). There is a need for a process in which use can be made of less high-quality pulps, i.e. pulps with a higher hemicellulose content. This would represent a considerable cost saving, because pulp prices are rela-tively high and cellulose acetate consists of approximately 60% cellulose.
The problem of the invention is consequently to provide a process for the production of cellulose acetate with a DS between 1.5 and 2.9, which requires the use of smaller acetylating agent quantities than the known processes and in particular requires no detour via cellulose triacetate.
It is intended to supply cellulose acetates with a substantially homogen-eous substituent distribution. The process must also permit the use of less high-quality pulps, in that the admixtures such as hemicelluloses, li ~ - . __,s_~___LS__ ..L_ _..",~.... .,..a AMENDED SHEET
further processing of cellulose acetate-disturbing admixtures, such as hemi-celluloses, lignin, fats, etc., in process stages consuming no acetylating agent.
According to the invention this problem is solved in that in a first stage the cellulose is impregnated with excess base, the base is removed again to a molar ratio of base:anhydroglucose units (AHG) of less than 2.5 and, accompanied by base catalysis, the cellulose is reacted with a first acetylating agent to cellulose acetate With a DS of less than 1 and in a second stage, accompanied by acid catalysis, with a second acetylating agent to cellulose acetate with a DS of 1.5 to 2.9.
Bases catalyzing the first stage of the process according to the invention are either liquid or in the form of a solution, preferably aqueous solution.
The bases or their solutions are able to swell the cellulose, i.e. they are able to penetrate the crystalline areas of the cellulose and in this way activate the latter. By acetylating to a DS of less than 1 the activation state is preserved. It is assumed that the acetyl groups present in low substituent density act as "spacers", which prevent a recrystallization of the cellulose chains, if the base is consumed by the reaction or removed in any other way.
The base for the catalysis of the first stage of the process according to the invention is preferably caustic soda solution, particularly aqueous caustic soda solution, preferably with a concentration of at least 20%.
In a preferred embodiment, in the first stage, the cellulose is impregnated with an excess of base and the base is removed to a molar ratio of base:AHG
(anhydroglucose units) of less than 1 and subsequently the product obtained is reacted with the first acetylating agent to a cellulose acetate with a DS of less than 1.
"Excess of base" means that the base or its solution must at least com-pletely wet the surface of the cellulose. Conventionally a molar ratio Amended sheet 3a 20 as facilitates the homogeneous penetration of the cellulose with base. The base is then largely removed again in order to minimize the formation of byproducts from the reaction of the base with the first acetylating agent.
Preferably the base is removed again to the base quantity stoichiometric-ally necessary for the formation of the cellulose acetate with DS < 1. Pref-erence is given to residual base quantities of approximately 2 to 5 wt.%
base (solvent-free calculation basis), based on the cellulose. On removing the base excess simultaneously undesired admixtures of cellulose, such as lignin, hemicelluloses, fats, etc. are removed. It is e.g. known that hemicelluloses are soluble in caustic soda solution, particularly in the 30 concentration range preferred in the process according to the invention and can be separated from insoluble pulp by squeezing or pres,'sing out (cf.
K. Gotze, Chemiefasern nach dem Viskoseverfahren, 3rd edition, Springer-AMENDED SHEET
According to the invention this problem is solved in that in a first stage the cellulose is impregnated with excess base, the base is removed again to a molar ratio of base:anhydroglucose units (AHG) of less than 2.5 and, accompanied by base catalysis, the cellulose is reacted with a first acetylating agent to cellulose acetate With a DS of less than 1 and in a second stage, accompanied by acid catalysis, with a second acetylating agent to cellulose acetate with a DS of 1.5 to 2.9.
Bases catalyzing the first stage of the process according to the invention are either liquid or in the form of a solution, preferably aqueous solution.
The bases or their solutions are able to swell the cellulose, i.e. they are able to penetrate the crystalline areas of the cellulose and in this way activate the latter. By acetylating to a DS of less than 1 the activation state is preserved. It is assumed that the acetyl groups present in low substituent density act as "spacers", which prevent a recrystallization of the cellulose chains, if the base is consumed by the reaction or removed in any other way.
The base for the catalysis of the first stage of the process according to the invention is preferably caustic soda solution, particularly aqueous caustic soda solution, preferably with a concentration of at least 20%.
In a preferred embodiment, in the first stage, the cellulose is impregnated with an excess of base and the base is removed to a molar ratio of base:AHG
(anhydroglucose units) of less than 1 and subsequently the product obtained is reacted with the first acetylating agent to a cellulose acetate with a DS of less than 1.
"Excess of base" means that the base or its solution must at least com-pletely wet the surface of the cellulose. Conventionally a molar ratio Amended sheet 3a 20 as facilitates the homogeneous penetration of the cellulose with base. The base is then largely removed again in order to minimize the formation of byproducts from the reaction of the base with the first acetylating agent.
Preferably the base is removed again to the base quantity stoichiometric-ally necessary for the formation of the cellulose acetate with DS < 1. Pref-erence is given to residual base quantities of approximately 2 to 5 wt.%
base (solvent-free calculation basis), based on the cellulose. On removing the base excess simultaneously undesired admixtures of cellulose, such as lignin, hemicelluloses, fats, etc. are removed. It is e.g. known that hemicelluloses are soluble in caustic soda solution, particularly in the 30 concentration range preferred in the process according to the invention and can be separated from insoluble pulp by squeezing or pres,'sing out (cf.
K. Gotze, Chemiefasern nach dem Viskoseverfahren, 3rd edition, Springer-AMENDED SHEET
Verlag, Berlin, Heidelberg, New York, 1967). It is therefore a mayor advantage of the process according to the invention that hemicelluloses are separated in the first process stage and therefore cannot have a disturbing effect during the processing of the products. It is also advantageous that as a result it is possible to use less refined and therefore less costly pulps with a higher hemicellulose content. The undesired admixtures can be separated from the base in a suitable way and the base can be reused. The base can be recycled by discharging the cellulose admixtures.
The removal of excess base can take place by the mechanical pressing out of the impregnated cellulose. Alternatively or preferably in addition to pressing out, the impregnated cellulose can be rinsed with a water-miscible, polar, organic solvent. The solvent is preferably chosen from among mono-hydric, dihydric or trihydric C1-C4 alcohols and amines. The monohydric alcohol is preferably methanol or ethanol and the dihydric alcohol is ethylene glycol.
As a result of this measure it is easily possible to reduce the base con-tent of the cellulose to the extent stoichiometrically necessary for react-ing with acetylating agent to the cellulose acetate with a DS of less than 1. Surprisingly, on washing out with the water-miscible, polar, organic solvent, the amorphous, reactive state of the alkali cellulose is main-tained. By mixing with the first acetylating agent, particularly acetic anhydride, at ambient temperature a partly acetylated cellulose acetate with a DS of less than 1 is obtained. If use is made of an alcohol, prefer-ably a monohydric alcohol for washing out, it can be advantageously recovered by distillation. The residual alcohol still present in the alkali cellulose following the rinsing stage does not react with the acetylating agent.
The cellulose acetate with a DS of less than 1 obtained in the first stage of the process according to the invention can be stored following washing with Water and drying. Alternatively washing can also take place with glacial acetic acid. Washing permits the removal of residues of organic solvent, first acetylating agent and particularly the reaction product formed from the catalyst base and the first acetylating agent, e.g. sodium acetate when using caustic soda solution.
The cellulose acetate obtained in the first process stage has a degree of substitution of less than 1, preferably less than 0.6 and in particular between 0.1 and 0.5. It has a fibrous structure and according to the X-ray diffraction spectrum is completely decrystallized. It has a uniform reactivity and is consequently a suitable substrate for the second process stage, in which the cellulose acetate with the desired DS is now directly obtained, i.e. without the detour via triacetate.
In the second stage of the process according to the invention, the cellu-lose acetate with a DS of less than about 1 obtained in the first stage, accompanied by the addition of the corresponding second acetylating agent quantity and accompanied by acid catalysis is directly reacted to cellulose acetate with the desired degree of substitution in the range 1.5 to 2.9, particularly 1.8 to 2.75 and in particularly preferred manner approximately 2.5. Preferably acetic anhydride is used as the second acetylating agent and preferably sulphuric acid is used as the catalyst.
The process according to the invention has numerous advantages. Thus, mercerization technology, i.e. the treatment of cellulose with base is well-used, proven and cost-effective in operation. Corresponding plants are used to a considerable extent throughout the world in viscose or cellulose ether production. Excess caustic soda solution can be recovered without significant cost. The setting of the degree of polymerization (DP) by con-tact with caustic soda solution is well known and proven from the viscose industry.
During mercerization the undesired admixtures of cellulose from the wood, such as hemicelluloses, lignin, fats, etc. are separated from the cellulose, which makes it possible to use much less refined pulps. Thus, it is in part possible to move pulp purification from pulp factories to the further processor.
To achieve the desired degree of substitution compared with the prior art a much smaller acetylating agent quantity is required. In the first stage an amorphous cellulose acetate with a low DS is produced and its further reaction to cellulose acetate with the desired DS takes place without the problems arising in the known heterogeneous acetylation process as a result of the crystalline cellulose fraction, such as inhomogeneous substituent distribution and low product uniformity. Acetylation takes place at ambi-ent temperature or slightly elevated temperatures. The products according to the invention are characterized by a substantially homogeneous substi-tuent distribution, which leads to an excellent solubility of the inventive products in acetone. Thus, apart from 2,5-cellulose acetates, also pro-ducts produced according to the invention with higher degrees of polymeriz-ation are soluble in acetone.
The invention will now be illustrated by the following examples:
Example 1 100 g of cellulose with a DP of 750 are suspended in 500 g of 22 wt.% caus-tic soda solution at 22°C in a 1 litre three-neck flask. After 15 min the mixture is pressed out in a laboratory chamber press at 150 bar. The press cake (250 g) is suspended in 750 g of methanol at ambient temperature and the alkali cellulose is filtered off. 150 g of methanol-containing alkali cellulose are then added in a thermostatable reaction vessel at 20°C to 150 g of acetic anhydride and reacted. After 10 min excess anhydride is filtered off and the decrystallized cellulose acetate is washed With water and dried, giving 103 g of cellulose acetate with a DS of 0.25.
For cellulose-2,5-acetate production, in a thermostatable reaction vessel 100 g of dried 0,25-CA are suspended at 60°C in 1.5 litre of glacial acetic acid (99%). After 15 min 105 g of acetic anhydride are added and stirring takes place for a further 5 min at 60°C. After adding 15 ml of a 1 wt.%
sulphuric acid solution in glacial acetic acid stirring takes place for 45 min at 60°C and the reaction mixture homogenizes. Following the pre-cipitation of 2,5-CA in water, washing the product several times and drying at 100°C, 150 g of cellulose-2,5-acetate are obtained.
The product is completely soluble in 1350 g of acetone. The solution is filtered and can be processed to cellulose-2,5-acetate products.
Examples 2 to 4 The cellulose-2,5-acetate is prepared in accordance with example 1, except for the fact that the 0,25-CA is not washed with water and dried, but is instead washed with acetic anhydride (example 2) or acetic acid (example 3) or is reacted directly without washing (example 4) to 2,5-CA.
In each case the products obtained are completely soluble in acetone.
The removal of excess base can take place by the mechanical pressing out of the impregnated cellulose. Alternatively or preferably in addition to pressing out, the impregnated cellulose can be rinsed with a water-miscible, polar, organic solvent. The solvent is preferably chosen from among mono-hydric, dihydric or trihydric C1-C4 alcohols and amines. The monohydric alcohol is preferably methanol or ethanol and the dihydric alcohol is ethylene glycol.
As a result of this measure it is easily possible to reduce the base con-tent of the cellulose to the extent stoichiometrically necessary for react-ing with acetylating agent to the cellulose acetate with a DS of less than 1. Surprisingly, on washing out with the water-miscible, polar, organic solvent, the amorphous, reactive state of the alkali cellulose is main-tained. By mixing with the first acetylating agent, particularly acetic anhydride, at ambient temperature a partly acetylated cellulose acetate with a DS of less than 1 is obtained. If use is made of an alcohol, prefer-ably a monohydric alcohol for washing out, it can be advantageously recovered by distillation. The residual alcohol still present in the alkali cellulose following the rinsing stage does not react with the acetylating agent.
The cellulose acetate with a DS of less than 1 obtained in the first stage of the process according to the invention can be stored following washing with Water and drying. Alternatively washing can also take place with glacial acetic acid. Washing permits the removal of residues of organic solvent, first acetylating agent and particularly the reaction product formed from the catalyst base and the first acetylating agent, e.g. sodium acetate when using caustic soda solution.
The cellulose acetate obtained in the first process stage has a degree of substitution of less than 1, preferably less than 0.6 and in particular between 0.1 and 0.5. It has a fibrous structure and according to the X-ray diffraction spectrum is completely decrystallized. It has a uniform reactivity and is consequently a suitable substrate for the second process stage, in which the cellulose acetate with the desired DS is now directly obtained, i.e. without the detour via triacetate.
In the second stage of the process according to the invention, the cellu-lose acetate with a DS of less than about 1 obtained in the first stage, accompanied by the addition of the corresponding second acetylating agent quantity and accompanied by acid catalysis is directly reacted to cellulose acetate with the desired degree of substitution in the range 1.5 to 2.9, particularly 1.8 to 2.75 and in particularly preferred manner approximately 2.5. Preferably acetic anhydride is used as the second acetylating agent and preferably sulphuric acid is used as the catalyst.
The process according to the invention has numerous advantages. Thus, mercerization technology, i.e. the treatment of cellulose with base is well-used, proven and cost-effective in operation. Corresponding plants are used to a considerable extent throughout the world in viscose or cellulose ether production. Excess caustic soda solution can be recovered without significant cost. The setting of the degree of polymerization (DP) by con-tact with caustic soda solution is well known and proven from the viscose industry.
During mercerization the undesired admixtures of cellulose from the wood, such as hemicelluloses, lignin, fats, etc. are separated from the cellulose, which makes it possible to use much less refined pulps. Thus, it is in part possible to move pulp purification from pulp factories to the further processor.
To achieve the desired degree of substitution compared with the prior art a much smaller acetylating agent quantity is required. In the first stage an amorphous cellulose acetate with a low DS is produced and its further reaction to cellulose acetate with the desired DS takes place without the problems arising in the known heterogeneous acetylation process as a result of the crystalline cellulose fraction, such as inhomogeneous substituent distribution and low product uniformity. Acetylation takes place at ambi-ent temperature or slightly elevated temperatures. The products according to the invention are characterized by a substantially homogeneous substi-tuent distribution, which leads to an excellent solubility of the inventive products in acetone. Thus, apart from 2,5-cellulose acetates, also pro-ducts produced according to the invention with higher degrees of polymeriz-ation are soluble in acetone.
The invention will now be illustrated by the following examples:
Example 1 100 g of cellulose with a DP of 750 are suspended in 500 g of 22 wt.% caus-tic soda solution at 22°C in a 1 litre three-neck flask. After 15 min the mixture is pressed out in a laboratory chamber press at 150 bar. The press cake (250 g) is suspended in 750 g of methanol at ambient temperature and the alkali cellulose is filtered off. 150 g of methanol-containing alkali cellulose are then added in a thermostatable reaction vessel at 20°C to 150 g of acetic anhydride and reacted. After 10 min excess anhydride is filtered off and the decrystallized cellulose acetate is washed With water and dried, giving 103 g of cellulose acetate with a DS of 0.25.
For cellulose-2,5-acetate production, in a thermostatable reaction vessel 100 g of dried 0,25-CA are suspended at 60°C in 1.5 litre of glacial acetic acid (99%). After 15 min 105 g of acetic anhydride are added and stirring takes place for a further 5 min at 60°C. After adding 15 ml of a 1 wt.%
sulphuric acid solution in glacial acetic acid stirring takes place for 45 min at 60°C and the reaction mixture homogenizes. Following the pre-cipitation of 2,5-CA in water, washing the product several times and drying at 100°C, 150 g of cellulose-2,5-acetate are obtained.
The product is completely soluble in 1350 g of acetone. The solution is filtered and can be processed to cellulose-2,5-acetate products.
Examples 2 to 4 The cellulose-2,5-acetate is prepared in accordance with example 1, except for the fact that the 0,25-CA is not washed with water and dried, but is instead washed with acetic anhydride (example 2) or acetic acid (example 3) or is reacted directly without washing (example 4) to 2,5-CA.
In each case the products obtained are completely soluble in acetone.
Claims (11)
1. Process for the production of cellulose acetate with a degree of substitution (DS) between 1.5 and 2.9 by reacting cellulose with an acetylating agent, characterized in that, in a first stage, the cellulose is impregnated with excess base, the base is removed again to a molar ratio of base:anhydroglucose units (AHG) of less than 2.5 and, accompanied by base catalysis, the cellulose is reacted with a first acetylating agent to cellulose acetate with a DS of less than 1 and in a second stage, accompanied by acid catalysis, with a second acetylating agent to cellulose acetate with a DS of 1.5 to 2.9.
2. Process according to claim 1, characterized in that in the second stage a DS of 1.8 to 2.75 is set.
3. Process according to claim 1 or 2, characterized in that the first acetylating agent is acetic anhydride.
4. Process according to one of the claims 1 to 3, characterized in that the second acetylating agent is acetic anhydride.
5. Process according to one of the preceding claims, characterized in that in the first stage caustic soda solution is used for base catalysis.
6. Process according to one of the preceding claims, characterized in that in the second stage sulphuric acid is used for acid catalysis.
7. Process according to one of the preceding claims, characterized in that the base is removed again to a molar ratio of less than 1.
8. Process according to one of the preceding claims, characterized in that the excess base is mechanically pressed out of the impregnated cellulose.
9. Process according to one of the preceding claims, characterized in that the excess base is removed by washing out the impregnated cellulose with a water-miscible, polar, organic solvent.
10. Process according to claim 9, characterized in that the water-miscible, polar, organic solvent is chosen from among monohydric, dihydric or tri-hydric C1-C4 alcohols and amines.
11. Process according to claim 10, characterized in that the monohydric alcohol is methanol or ethanol and the dihydric alcohol is ethylene glycol.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19711502.0 | 1997-03-19 | ||
| DE19711502A DE19711502C1 (en) | 1997-03-19 | 1997-03-19 | Process for the production of cellulose acetate |
| PCT/EP1998/000607 WO1998041543A1 (en) | 1997-03-19 | 1998-02-04 | Method for producing cellulose acetate |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2283980A1 true CA2283980A1 (en) | 1998-09-24 |
Family
ID=7823932
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002283980A Abandoned CA2283980A1 (en) | 1997-03-19 | 1998-02-04 | Method for producing cellulose acetate |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0970129B1 (en) |
| JP (1) | JP2000511588A (en) |
| AT (1) | ATE207936T1 (en) |
| AU (1) | AU6620298A (en) |
| BR (1) | BR9808353A (en) |
| CA (1) | CA2283980A1 (en) |
| DE (2) | DE19711502C1 (en) |
| WO (1) | WO1998041543A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11440973B2 (en) | 2017-01-25 | 2022-09-13 | Daicel Corporation | Cellulose acetate, cellulose acetate composition, molded article, and film |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BRPI0415764A (en) * | 2003-11-28 | 2006-12-26 | Eastman Chem Co | Interpolimer, reaction product, methods for converting a hydroxyl, for preparing a stable form of an interpolimer, for converting a primary alcohol, and for treating a mammal in need thereof, coating and oral pharmaceutical compositions, pigment dispersion, and, article |
| JP5757681B2 (en) | 2009-08-12 | 2015-07-29 | 富士フイルム株式会社 | CELLULOSE DERIVATIVE, RESIN COMPOSITION, MOLDED BODY, PROCESS FOR PRODUCING THE SAME, AND CASE FOR ELECTRICAL / Electronic Equipment |
| JP5470032B2 (en) | 2009-08-12 | 2014-04-16 | 富士フイルム株式会社 | Cellulose derivative, thermoforming material, molded body, method for producing the same, and casing for electric and electronic equipment |
| US20130096297A1 (en) * | 2011-10-14 | 2013-04-18 | Celanese Acetate Llc | Methods for Synthesizing Acylated Cellulose Through Instillation of an Acidic Catalyst |
| US20130096298A1 (en) * | 2011-10-14 | 2013-04-18 | Celanese Acetate Llc | Methods for Synthesizing Acylated Cellulose Through Instillation of an Acidic Catalyst |
| US20130096296A1 (en) * | 2011-10-14 | 2013-04-18 | Celanese Acetate Llc | Methods for Synthesizing Acylated Cellulose Through Instillation of an Acidic Catalyst |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE562712C (en) * | 1927-11-25 | 1932-10-28 | Otto Faust Dr | Process for the refinement of cellulose raw material of all kinds |
-
1997
- 1997-03-19 DE DE19711502A patent/DE19711502C1/en not_active Expired - Fee Related
-
1998
- 1998-02-04 AU AU66202/98A patent/AU6620298A/en not_active Abandoned
- 1998-02-04 JP JP10540055A patent/JP2000511588A/en active Pending
- 1998-02-04 DE DE59801963T patent/DE59801963D1/en not_active Expired - Fee Related
- 1998-02-04 WO PCT/EP1998/000607 patent/WO1998041543A1/en active IP Right Grant
- 1998-02-04 AT AT98908057T patent/ATE207936T1/en not_active IP Right Cessation
- 1998-02-04 EP EP98908057A patent/EP0970129B1/en not_active Expired - Lifetime
- 1998-02-04 CA CA002283980A patent/CA2283980A1/en not_active Abandoned
- 1998-02-04 BR BR9808353-8A patent/BR9808353A/en unknown
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11440973B2 (en) | 2017-01-25 | 2022-09-13 | Daicel Corporation | Cellulose acetate, cellulose acetate composition, molded article, and film |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0970129A1 (en) | 2000-01-12 |
| DE59801963D1 (en) | 2001-12-06 |
| JP2000511588A (en) | 2000-09-05 |
| DE19711502C1 (en) | 1998-07-30 |
| EP0970129B1 (en) | 2001-10-31 |
| AU6620298A (en) | 1998-10-12 |
| WO1998041543A1 (en) | 1998-09-24 |
| BR9808353A (en) | 2000-05-23 |
| ATE207936T1 (en) | 2001-11-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |