CN114716574A - Method for preparing carboxymethylated nanocellulose - Google Patents
Method for preparing carboxymethylated nanocellulose Download PDFInfo
- Publication number
- CN114716574A CN114716574A CN202110007001.9A CN202110007001A CN114716574A CN 114716574 A CN114716574 A CN 114716574A CN 202110007001 A CN202110007001 A CN 202110007001A CN 114716574 A CN114716574 A CN 114716574A
- Authority
- CN
- China
- Prior art keywords
- reaction
- carboxymethylated cellulose
- chloroacetic acid
- preparing
- etherification
- 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.)
- Pending
Links
Images
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
- C08B11/02—Alkyl or cycloalkyl ethers
- C08B11/04—Alkyl or cycloalkyl ethers with substituted hydrocarbon radicals
- C08B11/10—Alkyl or cycloalkyl ethers with substituted hydrocarbon radicals substituted with acid radicals
- C08B11/12—Alkyl or cycloalkyl ethers with substituted hydrocarbon radicals substituted with acid radicals substituted with carboxylic radicals, e.g. carboxymethylcellulose [CMC]
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F2/00—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof
- D01F2/24—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof from cellulose derivatives
- D01F2/28—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof from cellulose derivatives from organic cellulose esters or ethers, e.g. cellulose acetate
Abstract
The invention discloses a method for preparing carboxymethylated cellulose nanofibers, which comprises the following steps: firstly, preparing carboxymethylated cellulose crude fiber with low substitution degree through two alkalization reactions and two etherification reactions; then, processing the carboxymethylated cellulose crude fiber with low substitution degree by a physical method to prepare the carboxymethylated cellulose nanofiber. The method effectively reduces the defibering difficulty of the carboxymethylated cellulose crude fiber through two alkalization reactions and two etherification reactions, and improves the yield and the output of the carboxymethylated cellulose nano fiber produced by a physical method and the quality of the product.
Description
Technical Field
The invention belongs to the technical field of cellulose nanofiber preparation, and relates to a method for preparing carboxymethylated nanocellulose.
Background
Cellulose is a natural high molecular compound and a renewable resource which are most abundant on the earth, widely exists in cell walls of various higher plants, algae, fungi and the like, and has the advantages of environmental protection, no toxicity, renewability, biodegradability, low density, low cost, easy modification and the like. The cellulose nanofiber is a cellulose product with the diameter of 1-100 nanometers and the length of hundreds of nanometers or even a few micrometers, and the unique nanometer size of the cellulose nanofiber endows the cellulose nanofiber with various excellent properties such as high Young modulus, high tensile strength, high specific surface area, low thermal expansion coefficient, high water retention, preferable suspension thickening performance, unique shear thinning performance and the like, so that the cellulose nanofiber can be widely applied to the fields of papermaking, flexible electronics, buildings, automobiles, foods, cosmetics, medicines, coatings, energy sources, aviation and the like.
Carboxymethyl cellulose is an ether derivative obtained by carboxymethylation of cellulose, is also a product with the largest yield, the widest application and the most convenient use in cellulose ethers, is commonly called as industrial monosodium glutamate, and is widely applied to a plurality of fields of petroleum, textile, printing, papermaking, coating, batteries, food, cosmetics, medicine, building and the like. The carboxymethylated cellulose nano-fiber is a novel high-tech nano-material prepared by a special process. The industrial synthesis method of carboxymethylated cellulose is characterized by that it utilizes sodium hydroxide to treat natural cellulose to form alkali fibre, then adds chloroacetic acid to make substitution reaction so as to obtain the invented product. When the substitution degree of the carboxymethyl cellulose is less than 0.5, the prepared carboxymethyl cellulose crude fiber is insoluble in water and keeps higher crystallinity; when the degree of substitution is greater than 0.5, the carboxymethylated cellulose crude fiber begins to dissolve in water, thereby forming a viscous transparent solution. The preparation of carboxymethylated cellulose nanofibers includes the steps of preparing coarse carboxymethylated cellulose fibers with low substitution degree, and then carrying out nanocrystallization by a physical method. However, the carboxymethylated cellulose crude fiber prepared by the one-time etherification method is difficult to defibrate, thereby causing the defects of high preparation cost, low yield, uneven product size, unstable quality, poor dispersibility and the like. The main reason is that during the etherification, the carboxymethylated cellulose prepared by one-time etherification has poor substitution uniformity, carboxymethyl groups are mainly distributed on the surfaces of an amorphous area and a crystalline area of the crude cellulose fiber, and substitution reaction rarely occurs in the crystalline area, so that the crude cellulose fiber is difficult to defibrate or even cannot be defibrated. Therefore, new methods for preparing carboxymethylated cellulose nanofibers are desired.
Disclosure of Invention
In order to solve the defects existing in the prior art, the invention aims to provide a novel method for preparing carboxymethylated cellulose nanofibers.
The method comprises the following specific steps:
a) soaking a cellulose raw material in a reaction solvent, adding alkali liquor into the raw material to perform a first alkalization reaction, and then adding chloroacetic acid solution to perform a first etherification reaction;
b) after a period of time, adding alkali liquor to carry out secondary alkalization reaction, and then adding chloroacetic acid solution to carry out secondary etherification reaction. Obtaining purified carboxymethylated cellulose crude fiber;
c) dispersing the purified carboxymethylated cellulose crude fiber in an aqueous solution to prepare a suspension with the mass concentration of about 0.5-4%. And (3) processing the carboxymethylated cellulose crude fiber by using a physical method to obtain the carboxymethylated cellulose nanofiber.
The reaction method adopted for preparing the carboxymethylated cellulose nanofibers is one or more of a water medium method, a solvent method, a slurry method and the like; preferably, the solvent method is used.
In the step a), the cellulose raw material is wood pulp, cotton pulp, bamboo pulp and other plant-derived cellulose raw materials.
In the step a), the reaction solvent is one or more of water, ethanol, isopropanol and the like.
In the step a), the alkali liquor is a sodium hydroxide aqueous solution, and the mass concentration of the sodium hydroxide aqueous solution is 40-60%; preferably, it is 50%.
In the step a), the chloroacetic acid solution is a chloroacetic acid solution of water, ethanol and isopropanol; preferably, it is an ethanolic solution of chloroacetic acid.
In the step a), the mass concentration of the chloroacetic acid solution is 10-60%; preferably, it is 50%.
In the step a), the feeding mass ratio of the cellulose to the chloroacetic acid is 1: (0.0059-1.7500), preferably, 1: (0.0100-0.5864).
In the step a), the feeding mass ratio of the cellulose to the sodium hydroxide is 1: (0.7407-2.2200), preferably, 1: (0.7407-0.9876).
In the step b), the alkali liquor and the chloroacetic acid solution are the same as those in the step a).
In the invention, the proportion of the dosage of the alkali liquor used in the first alkalization reaction to the total amount of the alkali liquor (the total amount of the alkali liquor used in the two alkalization reactions) is 0.1-0.9; preferably, it is 0.3 to 0.7.
In the invention, the proportion of the chloroacetic acid solution used in the first etherification reaction to the total amount of the chloroacetic acid solution (the sum of the chloroacetic acid solutions used in the two etherification reactions) and the proportion of the first alkali solution to the total amount of the alkali solution are kept the same.
In the invention, the temperature of the first alkalization reaction and the second alkalization reaction is 15-78 ℃; preferably, it is from 25 to 60 ℃.
In the invention, the time of the first alkalization reaction and the second alkalization reaction is 1-4 hours; preferably, it is 1 to 2 hours.
In the invention, the temperature for adding the chloroacetic acid solution is between 20 and 37 ℃; preferably, it is 20-25 ℃.
In the invention, the temperature of the first etherification reaction and the second etherification reaction is 60-82 ℃; preferably, it is 60 to 70 ℃.
In the invention, the time of the first etherification reaction and the second etherification reaction is 1 to 4 hours; preferably, it is 3 to 4 hours.
In the invention, the time interval of the two etherification reactions is 0.5-1 hour; preferably, it is 0.5 hour.
In the present invention, the degree of substitution of the carboxymethylated cellulose crude fiber is 0.01 to 0.5, preferably 0.02 to 0.3.
In the invention, the physical method comprises high-pressure homogenization, microjet and ultrasonic crushing; preferably, high pressure homogenization is performed.
In one embodiment, the preparation method comprises the following specific steps:
a) obtaining a cellulose raw material;
b) determining the feeding ratio of cellulose, alkali liquor and chloroacetic acid solution, and dividing the alkali liquor and the chloroacetic acid solution into two parts according to the feeding ratio of two times of alkalization reaction and two times of etherification reaction;
c) soaking a cellulose raw material in a reaction solvent;
d) adding a first part of alkali liquor into the raw materials for carrying out a first alkalization reaction, and then adding a first part of chloroacetic acid solution for carrying out a first etherification reaction;
e) after a period of time, adding a second part of alkali liquor to perform a secondary alkalization reaction, and then adding a second part of chloroacetic acid solution to perform a secondary etherification reaction;
f) after the reaction is finished, washing the product by using 60-70% volume concentration ethanol water solution to obtain purified carboxymethylated cellulose crude fiber;
g) dispersing the purified carboxymethylated cellulose crude fiber in an aqueous solution to prepare a suspension with the mass concentration of about 0.5-4%;
h) and (3) processing the carboxymethylated cellulose crude fiber by using a physical method to obtain the carboxymethylated cellulose nanofiber.
The principle of the invention is that carboxymethyl groups are uniformly introduced into the cellulose crude fiber by a secondary etherification method, and the steric hindrance effect of the carboxymethyl groups and the electrostatic repulsion between the groups effectively act between cellulose nano fibrils to promote the effective defibration of the cellulose crude fiber, thereby reducing the energy required by nanocrystallization and improving the yield and the product quality.
The invention also provides carboxymethylated nanocellulose prepared based on the preparation method.
The substitution degree of the carboxymethylated cellulose crude fiber is 0.01-0.5.
The beneficial effects of the invention include: compared with a primary etherification method, the method has the advantages that: after the raw materials are etherified for one time, the introduced carboxymethyl groups mainly exist in the amorphous regions and the surfaces of the crude cellulose fibers, and the defibering difficulty is high; after the secondary etherification, a carboxymethyl group is introduced into the cellulose crude fiber and the defibration is promoted, so that the defibration difficulty of the carboxymethylated cellulose crude fiber is effectively reduced, and the yield, the output and the product quality of the carboxymethylated cellulose nano fiber produced by a physical method are improved; the efficiency of the carboxymethylated cellulose nano-fiber obtained by the one-step etherification method is 10-50%, the fiber size is nano-sized to micron-sized, the uniformity is poor, and therefore, the product has poor stability, easy layering and precipitation and low viscosity; the efficiency of the secondary ether method is 90-100%, the fiber size is nano-scale, the homogeneity is good, therefore, the product stability is high, the layering precipitation is avoided, and the viscosity is high.
Drawings
FIG. 1 is an aqueous suspension of carboxymethylated cellulose crude fibers prepared in examples 1 and 2 of the present invention, wherein the sample on the left is sample No. 1 and the sample on the right is sample No. 2;
FIG. 2 is an aqueous suspension of carboxymethylated cellulose nanofibers prepared in examples 1 and 2 of the present invention, wherein the sample on the left is sample No. 1 and the sample on the right is sample No. 2;
FIG. 3 is an X-ray diffraction pattern of sample No. 1 of the present invention;
FIG. 4 is an X-ray diffraction pattern of sample No. 2 of the present invention;
FIG. 5 is a scanning electron microscope photograph of sample No. 1 according to the present invention;
FIG. 6 is a scanning electron microscope photograph of sample No. 2 according to the present invention;
FIG. 7 is an aqueous carboxymethylated cellulose nanofiber suspension prepared in example 3 of the present invention at a concentration of 0.5% by mass;
FIG. 8 is an aqueous carboxymethylated cellulose nanofiber suspension prepared in example 4 of the present invention, left to stand for 10 minutes;
FIG. 9 is an aqueous suspension of carboxymethylated cellulose nanofibers prepared in example 4 of the present invention, placed at an angle;
FIG. 10 is an aqueous carboxymethylated cellulose nanofiber suspension prepared in example 5 of the present invention, left to stand for 10 minutes;
FIG. 11 is an aqueous suspension of carboxymethylated cellulose nanofibers prepared in example 5 of the present invention, laid flat;
figure 12 is an aqueous suspension of carboxymethylated cellulose nanofibers prepared in example 6 of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the following specific examples and the accompanying drawings. The procedures, conditions, experimental methods and the like for carrying out the present invention are general knowledge and common general knowledge in the art except for the contents specifically mentioned below, and the present invention is not particularly limited.
Example 1
The method for preparing the carboxymethylated cellulose nanofibers with lower substitution degree by using a wood pulp powder secondary etherification method has the following specific implementation mode:
1. obtaining a cellulose raw material: weighing 6.60 g of wood pulp powder (containing 10% of water);
2. calculating the feeding ratio: feeding 50% of alkali liquor and chloroacetic acid solution used in the first alkalization reaction and etherification reaction based on the mass ratio of cellulose, sodium hydroxide and chloroacetic acid of 1:0.98: 0.58; weighing 3.48 g of chloroacetic acid solid, dissolving in 10 ml of ethanol, and averagely dividing into 2 parts for later use, weighing 5.90 g of sodium hydroxide solid, dissolving in 6 ml of water, and averagely dividing into 2 parts for later use;
3. soaking cellulose raw materials: soaking the weighed wood pulp powder in absolute ethyl alcohol, and continuously mechanically stirring to uniformly disperse the wood pulp powder;
4. first alkalization reaction and etherification reaction: adding the first alkali liquor into the stirring system to carry out an alkalization reaction at room temperature (25 ℃) for 1 hour; slowly adding a first part of chloroacetic acid, heating to 60 ℃ after the acid is added, and carrying out etherification reaction for 4 hours;
5. and (3) carrying out second alkalization reaction and etherification reaction: removing the heat source after the first etherification reaction is finished until the reaction system is recovered to the room temperature, and then adding a second part of alkali liquor to carry out a secondary alkalization reaction for 1 hour; then slowly adding a second part of chloroacetic acid, and after the acid is added, heating to 60 ℃ for a second etherification reaction, wherein the reaction time is 4 hours;
6. and (3) purifying a product: after the reaction is finished, removing a heat source, cooling to room temperature, filtering to obtain a product (filter residue), and cleaning the product for 5 times by using 60% ethanol with volume concentration to obtain a white product, namely carboxymethylated cellulose crude fiber;
7. and (3) resuspending the product: dispersing the washed product in water to obtain a suspension with a mass concentration of about 1% (see sample No. 1 in FIG. 1);
8. defibration of carboxymethylated cellulose crude fiber: processing the prepared carboxymethylated cellulose crude fiber suspension by using a high-pressure homogenizer, and homogenizing by using 30 MPa, 50 MPa and 80 MPa respectively in sequence for one time to defibrate the carboxymethylated cellulose crude fiber to obtain a carboxymethylated cellulose nanofiber product (see a sample No. 1 in figure 2);
9. degree of substitution and crystallinity and morphology analysis: the degree of substitution of the sample was 0.084 by conductivity titration, the degree of crystallinity was 66.43% by X-ray diffraction technique (fig. 3), and the size of the nanofibers was analyzed by scanning electron microscopy (fig. 5) to be about 20 to 60 nanometers.
Example 2
A secondary etherification method of wood pulp powder is used for preparing carboxymethylated cellulose nano-fiber with higher substitution degree, and the specific implementation mode is as follows:
1. obtaining a cellulose raw material: weighing 6.60 g of wood pulp powder (containing 10% of water);
2. calculating the feeding ratio: feeding 50% of alkali liquor and chloroacetic acid solution used in the first alkalization reaction and etherification reaction based on the mass ratio of cellulose, sodium hydroxide and chloroacetic acid of 1:1.23: 1.16; weighing 6.96 g of chloroacetic acid solid, dissolving in 20 ml of ethanol, and averagely dividing into 2 parts for later use, weighing 7.40 g of sodium hydroxide solid, dissolving in 6 ml of water, and averagely dividing into 2 parts for later use;
3. soaking a cellulose raw material: soaking the weighed wood pulp powder in absolute ethyl alcohol, and continuously mechanically stirring to uniformly disperse the wood pulp powder;
4. first alkalization reaction and etherification reaction: adding the first alkali liquor into the stirring system to carry out an alkalization reaction at room temperature (25 ℃) for 1 hour; slowly adding a first part of chloroacetic acid, and heating to 60 ℃ after the acid is added to perform etherification reaction for 4 hours;
5. and (3) carrying out second alkalization reaction and etherification reaction: removing the heat source after the first etherification reaction is finished until the reaction system is recovered to the room temperature, and then adding a second part of alkali liquor to carry out a secondary alkalization reaction for 1 hour; then slowly adding a second part of chloroacetic acid, and after the acid is added, heating to 60 ℃ to perform a second etherification reaction for 4 hours;
6. and (3) purifying a product: after the reaction is finished, removing a heat source, cooling to room temperature, filtering to obtain a product (filter residue), and cleaning the product for 5 times by using 70% ethanol by volume concentration to obtain a white carboxymethylated cellulose crude fiber product.
7. And (3) resuspending the product: dispersing the washed product in water to obtain a suspension with a mass concentration of about 1% (see sample No. 2 in FIG. 1);
8. defibration of carboxymethylated cellulose crude fiber: processing the prepared carboxymethylated cellulose crude fiber suspension by using a high-pressure homogenizer, and homogenizing by using 30 MPa, 50 MPa and 80 MPa respectively in sequence for one time to defibrate the carboxymethylated cellulose crude fiber to obtain a carboxymethylated cellulose nanofiber product (see a sample No. 2 in figure 2);
9. degree of substitution and crystallinity analysis: the degree of substitution of the sample measured by conductivity titration was 0.212, the degree of crystallinity was 59.07% as measured by X-ray diffraction technique (fig. 4), and the nanofiber particle size was about 10 to 40 nm as analyzed by scanning electron micrograph (fig. 6).
Example 3
The carboxymethylated cellulose nanofiber is prepared by a secondary etherification method of cotton pulp powder, and the specific implementation mode is as follows:
1. obtaining a cellulose raw material: weighing 6.60 g of cotton pulp powder (containing 10% of water);
2. calculating a feeding ratio: feeding 60 percent of alkali liquor and chloroacetic acid used in the first alkalization reaction and etherification reaction based on the mass ratio of cellulose, sodium hydroxide and chloroacetic acid of 1:0.98: 0.58; weighing 3.48 g of chloroacetic acid solid, dissolving in 20 ml of ethanol, and dividing into 2 parts according to the ratio of 6:4 for later use, weighing 5.86 g of sodium hydroxide solid, dissolving in 6 ml of water, and dividing into 2 parts according to the ratio of 6:4 for later use;
3. soaking cellulose raw materials: soaking the weighed cotton pulp powder in absolute ethyl alcohol, and continuously mechanically stirring to uniformly disperse the cotton pulp powder;
4. first alkalization reaction and etherification reaction: adding the first part of alkali liquor into the stirring system to carry out an alkalization reaction, wherein the reaction temperature is 37 ℃, and the reaction time is 2 hours; after the alkalization reaction is finished, cooling to room temperature (25 ℃), then slowly adding a first part of chloroacetic acid, after the acid is added, heating to 78 ℃ for etherification reaction, wherein the reaction time is 4 hours;
5. and (3) carrying out second alkalization reaction and etherification reaction: removing the heat source after the first etherification reaction is finished until the reaction system is reduced to 37 ℃, adding a second part of alkali liquor to carry out a secondary alkalization reaction, and reacting for 2 hours; after the alkalization reaction is finished, cooling to room temperature (25 ℃), then slowly adding a second part of chloroacetic acid, after the acid is added, heating to 78 ℃ for a second etherification reaction, wherein the reaction time is 4 hours;
6. and (3) purifying a product: after the reaction is finished, removing a heat source, cooling to room temperature, filtering to obtain a product (filter residue), and cleaning the product for 5 times by using 70% ethanol by volume concentration to obtain a white carboxymethylated cellulose crude fiber product.
7. And (3) resuspending the product: dispersing the cleaned product in water to prepare a suspension with the mass concentration of about 1%;
8. defibration of carboxymethylated cellulose crude fiber: firstly, the suspension is pretreated by an ultrasonic crusher, and is crushed by 1200 watts of ultrasound for 5 minutes, then is further treated by a high-pressure homogenizer, and is homogenized once by 30 MPa, 50 MPa and 80 MPa in sequence to obtain a carboxymethylated cellulose nanofiber product (figure 7).
9. And (3) analysis of degree of substitution: the degree of substitution of the sample was 0.120 as determined by conductivity titration.
Example 4
The carboxymethylated cellulose nanofiber is prepared by a wood pulp powder one-step etherification method, and the specific implementation mode is as follows:
1. obtaining a cellulose raw material: weighing 13.20 g of wood pulp powder (containing 10% of water);
2. calculating the feeding ratio: feeding cellulose, sodium hydroxide and chloroacetic acid according to the mass ratio of 1:0.75: 1.0; weighing 12.0 g of chloroacetic acid solid to be dissolved in 24 ml of ethanol, weighing 9 g of sodium hydroxide solid to be dissolved in 9 ml of water;
3. soaking a cellulose raw material: soaking the weighed cotton pulp powder in absolute ethyl alcohol, and continuously mechanically stirring to uniformly disperse the cotton pulp powder;
4. alkalization reaction and etherification reaction: adding alkali liquor into the stirring system to carry out an alkalization reaction, wherein the reaction temperature is 25 ℃, and the reaction time is 1 hour; then slowly adding chloroacetic acid solution, after the acid is added, heating to 60 ℃ for etherification reaction, wherein the reaction time is 4 hours;
5. and (3) purifying a product: after the reaction is finished, removing the heat source, cooling to room temperature, filtering to obtain a product (filter residue), and cleaning the product for 5 times by using 70% ethanol by volume to obtain a white carboxymethylated cellulose crude fiber product.
6. And (3) resuspending the product: dispersing the cleaned product in water to obtain suspension with the mass concentration of about 1.25%;
7. defibration of carboxymethylated cellulose crude fiber: firstly, pretreating the suspension by using an ultrasonic crusher, crushing the suspension by using 1200 watts of ultrasonic for 10 minutes, then further treating the suspension by using a high-pressure homogenizer, and homogenizing the suspension once by using 30 MPa, 60 MPa and 100 MPa in sequence to obtain a carboxymethylated cellulose nanofiber product; layering occurs after standing for 10 minutes (fig. 8), and the longer the standing time is, the more serious the layering is; the product has low viscosity and strong fluidity, and the liquid level is kept horizontal all the time when the product is placed obliquely (figure 9);
8. centrifuging by a high-speed centrifuge under the conditions of 2000 r/min and 10 min to obtain carboxymethylated cellulose crude fiber precipitate which is not nano-sized, drying and weighing 9.31 g, and calculating to obtain the nano-sized product with the yield of 22.42%.
Example 5
The method for preparing the carboxymethylated cellulose nano-fiber by using the wood pulp powder secondary etherification method has the following specific implementation mode:
1. obtaining a cellulose raw material: weighing 13.20 g of wood pulp powder (containing 10% of water);
2. calculating the feeding ratio: feeding 50% of alkali liquor and chloroacetic acid used in the first alkalization reaction and etherification reaction based on the mass ratio of cellulose, sodium hydroxide and chloroacetic acid of 1:0.75: 1.0; weighing 12.0 g of chloroacetic acid solid, dissolving in 24 ml of ethanol, and dividing into two parts according to the ratio of 5:5 for later use, weighing 9 g of sodium hydroxide solid, dissolving in 9 ml of water, and dividing into two parts according to the ratio of 5:5 for later use;
3. soaking a cellulose raw material: soaking the weighed cotton pulp powder in absolute ethyl alcohol, and continuously mechanically stirring to uniformly disperse the cotton pulp powder;
4. adding the first part of alkali liquor into the stirring system to carry out an alkalization reaction, wherein the reaction temperature is 25 ℃, and the reaction time is 1 hour; slowly adding a first part of chloroacetic acid, heating to 60 ℃ after the acid is added, and carrying out etherification reaction for 2 hours;
5. and (3) carrying out second alkalization reaction and etherification reaction: removing the heat source after the first etherification reaction is finished until the reaction system is cooled to 25 ℃, adding a second part of alkali liquor to carry out a second alkalization reaction, and reacting for 1 hour; then slowly adding a second part of chloroacetic acid, and after the acid is added, heating to 60 ℃ for a second etherification reaction, wherein the reaction time is 2 hours;
6. and (3) purifying a product: after the reaction is finished, removing a heat source, cooling to room temperature, filtering to obtain a product (filter residue), and cleaning the product for 5 times by using 70% ethanol by volume concentration to obtain a white carboxymethylated cellulose crude fiber product.
7. And (3) resuspending the product: dispersing the cleaned product in water to prepare a suspension with the mass concentration of about 1.25%;
8. defibration of carboxymethylated cellulose crude fiber: firstly, pretreating the suspension by using an ultrasonic crusher, crushing the suspension by using 1200 watts of ultrasonic for 10 minutes, then further treating the suspension by using a high-pressure homogenizer, and homogenizing the suspension once by using 30 MPa, 60 MPa and 100 MPa in sequence to obtain a carboxymethylated cellulose nanofiber product; no layering phenomenon exists after the mixture is kept stand for 10 minutes, bubbles can be locked (figure 10), and the mixture can be kept stable after the time is prolonged to 1 month; the product has high viscosity and poor fluidity, keeps gel, and does not flow out of the beaker when placed horizontally (figure 11);
9. and (3) centrifuging by using a high-speed centrifuge under the conditions of 2000 rpm and 10 minutes, wherein no precipitate appears, the rotation speed is increased to 11000 rpm and is still stable, no precipitate exists, the product loss in the operation process is not counted, and the yield of the nano product is 100%.
Example 6
The method for preparing the carboxymethylated cellulose nano-fiber by using the wood pulp powder secondary etherification method has the following specific implementation mode:
1. obtaining a cellulose raw material: weighing 13.20 g of wood pulp powder (containing 10% of water);
2. calculating the feeding ratio: feeding 50% of alkali liquor and chloroacetic acid used in the first alkalization reaction and etherification reaction based on the mass ratio of cellulose, sodium hydroxide and chloroacetic acid of 1:0.75: 0.2; weighing 2.4 g of chloroacetic acid solid, dissolving in 4.8 ml of water, and dividing into two parts according to the ratio of 5:5 for later use, weighing 9 g of sodium hydroxide solid, dissolving in 9 ml of water, and dividing into two parts according to the ratio of 5:5 for later use;
3. soaking a cellulose raw material: soaking the weighed cotton pulp powder in water, and continuously mechanically stirring to uniformly disperse the cotton pulp powder;
4. adding the first part of alkali liquor into the stirring system to carry out an alkalization reaction, wherein the reaction temperature is 25 ℃, and the reaction time is 1 hour; slowly adding a first part of chloroacetic acid, heating to 60 ℃ after the acid is added, and carrying out etherification reaction for 2 hours;
5. and (3) carrying out second alkalization reaction and etherification reaction: removing the heat source after the first etherification reaction is finished until the reaction system is cooled to 25 ℃, adding a second part of alkali liquor to carry out a second alkalization reaction, and reacting for 1 hour; then slowly adding a second part of chloroacetic acid, and after the acid is added, heating to 60 ℃ for a second etherification reaction, wherein the reaction time is 2 hours;
6. and (3) purifying a product: after the reaction is finished, removing a heat source, cooling to room temperature, filtering to obtain a product (filter residue), and cleaning the product for 5 times by using 70% ethanol by volume concentration to obtain a white carboxymethylated cellulose crude fiber product.
7. And (3) resuspending a product: dispersing the cleaned product in water to obtain suspension with the mass concentration of about 1.0%;
8. defibration of carboxymethylated cellulose crude fiber: pretreating the suspension by using an ultrasonic crusher, crushing the suspension by using 1200 watts of ultrasonic for 10 minutes, further treating the suspension by using a high-pressure homogenizer, and homogenizing the suspension once by using 30 MPa, 60 MPa and 100 MPa in sequence to obtain a carboxymethylated cellulose nanofiber product (figure 12);
9. and (3) analysis of degree of substitution: the degree of substitution was 0.035 as determined by a conductivity meter titration method.
The protection of the present invention is not limited to the above embodiments. Variations and advantages that may occur to those skilled in the art may be incorporated into the invention without departing from the spirit and scope of the inventive concept, which is set forth in the following claims.
Claims (11)
1. A method of preparing carboxymethylated cellulose nanofibers, comprising the steps of:
a) soaking a cellulose raw material in a reaction solvent, adding alkali liquor into the raw material to perform a first alkalization reaction, and adding chloroacetic acid solution to perform a first etherification reaction;
b) after a period of time, adding alkali liquor to carry out secondary alkalization reaction, and then adding chloroacetic acid solution to carry out secondary etherification reaction to obtain purified carboxymethylated cellulose crude fiber;
c) dispersing the purified carboxymethylated cellulose crude fiber in an aqueous solution to prepare a suspension with the mass concentration of 0.5-4%, and treating the carboxymethylated cellulose crude fiber by using a physical method to obtain the carboxymethylated cellulose nanofiber.
2. The method for preparing carboxymethylated cellulose nanofibers according to claim 1, wherein the reaction method adopted for preparing carboxymethylated cellulose nanofibers is one or more of an aqueous medium method, a solvent method and a slurry method.
3. The method for preparing carboxymethylated cellulose nanofibers according to claim 1, characterized in that in step a) the cellulosic raw material is wood pulp, cotton pulp, bamboo pulp and other plant derived cellulosic raw materials;
and/or the mass ratio of the cellulose to the chloroacetic acid is 1: (0.0059-1.7500);
and/or the mass ratio of the cellulose to the sodium hydroxide is 1: (0.7407-2.2200).
4. The method for preparing carboxymethylated cellulose nanofibers according to claim 1, characterized in that the ratio of the amount of alkali liquor used in the first alkalization reaction to the total amount of alkali liquor is 0.1-0.9;
and/or the proportion of the dosage of the chloroacetic acid solution used in the first etherification reaction to the total amount of the chloroacetic acid solution is 0.1-0.9.
5. The method for preparing carboxymethylated cellulose nanofibers according to claim 1, wherein the reaction solvent is one or more of water, ethanol, isopropanol;
and/or the chloroacetic acid solution is a chloroacetic acid solution of water, ethanol and isopropanol, and the mass concentration of the chloroacetic acid solution is 10-60%.
6. The method for preparing carboxymethylated cellulose nanofibers according to claim 1, wherein the alkali solution is an aqueous sodium hydroxide solution with a mass concentration of 40-60%.
7. The method for preparing carboxymethylated cellulose nanofibers according to claim 1, wherein the temperature of the first alkalization reaction and the second alkalization reaction are both 15-78 ℃;
and/or the time of the first alkalization reaction and the second alkalization reaction is 1-4 hours.
8. The method for preparing carboxymethylated cellulose nanofibers according to claim 1, characterized in that the temperature at the time of addition of the chloroacetic acid solution is between 20-37 ℃;
and/or the temperature of the first etherification reaction and the second etherification reaction is 60-82 ℃;
and/or the time of the first etherification reaction and the second etherification reaction is 1 to 4 hours.
9. The method for preparing carboxymethylated cellulose nanofibers according to claim 1, characterized in that the time interval between the two etherification reactions is 0.5 to 1 hour.
10. The method for preparing carboxymethylated cellulose nanofibers according to claim 1, characterized in that the average degree of substitution of the carboxymethylated cellulose crude fibers is 0.01 to 0.5.
11. The method for preparing carboxymethylated cellulose nanofibers according to claim 1, characterized in that the physical method is high pressure homogenization, microfluidization, ultrasonication.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110007001.9A CN114716574A (en) | 2021-01-05 | 2021-01-05 | Method for preparing carboxymethylated nanocellulose |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110007001.9A CN114716574A (en) | 2021-01-05 | 2021-01-05 | Method for preparing carboxymethylated nanocellulose |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114716574A true CN114716574A (en) | 2022-07-08 |
Family
ID=82234863
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110007001.9A Pending CN114716574A (en) | 2021-01-05 | 2021-01-05 | Method for preparing carboxymethylated nanocellulose |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114716574A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116695438A (en) * | 2023-08-08 | 2023-09-05 | 潍坊广栗新材料科技有限公司 | Preparation method of carboxymethyl cellulose long fiber with good hydrophilicity |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20050274663A1 (en) * | 2004-05-24 | 2005-12-15 | Roitman Lipa L | [Air and Water Conditioning System and Filter Media] |
| CN101003577A (en) * | 2006-01-20 | 2007-07-25 | 上海长光企业发展有限公司 | Technique for producing polyanionic cellulose with high degree of substitution |
| CN111433225A (en) * | 2017-12-07 | 2020-07-17 | 日本制纸株式会社 | Carboxymethylated cellulose and method for producing carboxymethylated cellulose nanofibers |
-
2021
- 2021-01-05 CN CN202110007001.9A patent/CN114716574A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20050274663A1 (en) * | 2004-05-24 | 2005-12-15 | Roitman Lipa L | [Air and Water Conditioning System and Filter Media] |
| CN101003577A (en) * | 2006-01-20 | 2007-07-25 | 上海长光企业发展有限公司 | Technique for producing polyanionic cellulose with high degree of substitution |
| CN111433225A (en) * | 2017-12-07 | 2020-07-17 | 日本制纸株式会社 | Carboxymethylated cellulose and method for producing carboxymethylated cellulose nanofibers |
Non-Patent Citations (1)
| Title |
|---|
| 裴继诚: "《植物纤维化学》", 31 May 2020, 中国轻工业出版社 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116695438A (en) * | 2023-08-08 | 2023-09-05 | 潍坊广栗新材料科技有限公司 | Preparation method of carboxymethyl cellulose long fiber with good hydrophilicity |
| CN116695438B (en) * | 2023-08-08 | 2023-10-20 | 潍坊广栗新材料科技有限公司 | Preparation method of carboxymethyl cellulose long fiber with good hydrophilicity |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP3045573B1 (en) | Cellulose nanofibers, method for producing same, aqueous dispersion using cellulose nanofibers, and fiber-reinforced composite material | |
| JP6417490B1 (en) | Carboxymethylated cellulose nanofiber | |
| JP5676860B2 (en) | Polysaccharide nanofibers and production method thereof, ionic liquid solution containing polysaccharide nanofibers and composite material | |
| JP6351821B1 (en) | Method for producing carboxymethylated cellulose nanofiber | |
| CN103060937B (en) | Preparation method of cellulose nanofiber | |
| JP6337225B1 (en) | Carboxymethylated cellulose nanofiber | |
| Malladi et al. | Importance of agriculture and industrial waste in the field of nano cellulose and its recent industrial developments: a review | |
| CN105646721A (en) | Preparation method of nanocellulose fibrils | |
| CN111433225A (en) | Carboxymethylated cellulose and method for producing carboxymethylated cellulose nanofibers | |
| CN107602709B (en) | Clean preparation method of carboxymethyl nano-cellulose material | |
| JP2019163388A (en) | Carboxymethylated cellulose | |
| JP2014181421A (en) | Cellulose microfibers, method for manufacturing the same, and dispersion | |
| Duan et al. | A simultaneous strategy for the preparation of acetylation modified cellulose nanofiber/polypropylene composites | |
| CN109970875A (en) | It is a kind of cellulose nano-fibrous and preparation method thereof | |
| Xu et al. | Properties of polyvinyl alcohol films composited with hemicellulose and nanocellulose extracted from artemisia selengensis straw | |
| WO2019111939A1 (en) | Carboxymethylated cellulose nanofibers | |
| Su et al. | Integrated production of cellulose nanofibers and sodium carboxymethylcellulose through controllable eco-carboxymethylation under mild conditions | |
| Jančíková et al. | The role of deep eutectic solvents in the production of cellulose nanomaterials from biomass | |
| CN114716574A (en) | Method for preparing carboxymethylated nanocellulose | |
| Zhou et al. | Cellulose-based polymers | |
| WO2019111941A1 (en) | Carboxymethylated cellulose nanofibers | |
| Hindi | Differentiation and synonyms standardization of amorphous and crystalline cellulosic products | |
| JP2019163389A (en) | Carboxymethylated cellulose | |
| JP6404516B1 (en) | Method for producing carboxymethylated cellulose | |
| JP7103803B2 (en) | Carboxymethylated cellulose nanofibers |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |