JP2010013549A - Carboxylethyl cellulose - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a carboxylethyl cellulose which is water-soluble, contains very little carbamoylethyl group and is usable effectively as a chemically synthesized article; and to provide such a method for manufacturing a carboxylethyl cellulose as is efficient and has a side reaction suppressed. <P>SOLUTION: The carboxylethyl cellulose is characterized by having the degree of substitution of a carboxylethyl group of 0.2-2.8, the degree of substitution of a carbamoylethyl group of 0.04 or less and the degree of polymerization of 2-3,000; and the method for manufacturing hereof is also disclosed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to carboxylethyl cellulose having a carboxylethyl group substitution degree of 0.2 to 2.8, a carbamoylethyl group substitution degree of 0.04 or less, and a polymerization degree of 2 to 3000, and a method for producing the same. About.

Cellulose accounts for about 50% of the main plant components, and is the most produced biomass on earth. In recent years, due to environmental problems such as the depletion of fossil resources such as petroleum and the increase in carbon dioxide due to combustion, the conversion of cellulose, which is reproducible and carbon neutral, to an alternative to petroleum has attracted attention. In particular, an organic solvent in which a functional group is introduced into a free hydroxyl group of cellulose and a cellulose derivative that is soluble in water are still used in various fields from the viewpoint of moldability and ease of handling.
For example, cellulose acetate (CA) is dissolved in an organic solvent such as acetone and is used in the fields of fibers, filters, plastics, films, and paints. In addition, methyl cellulose (MC), hydroxypropyl methyl cellulose (HPMC), carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC) and the like are all water-soluble, but their aqueous solution characteristics are greatly different (for example, thixotropic properties: CMC aqueous solution). Large, small MC aqueous solution, thermal gelation: MC aqueous solution, no CMC aqueous solution), widely used in application fields (foodstuffs, pharmaceuticals, cosmetics, building materials, etc.) according to the characteristics.
Thus, since a cellulose derivative expresses an original function by the structure of a functional group, it can be said that the utility value will further increase in the future by creating a cellulose derivative having a novel structure.

On the other hand, in recent years, environmental regulations such as the Pollution Control Basic Law and the Air Pollution Control Law have been advanced in Japan, and water-based synthetic resin as a main component is required as a VOC reduction measure for paints, adhesives, inks, etc. Therefore, development of a novel water-soluble cellulose derivative that can be used in these fields is expected.
The idea of making the cellulose aqueous is to introduce hydrophilic groups such as amide groups and carboxyl groups. Patent Document 1 discloses that carboxyethyl cellulose having a carboxyethyl group can be synthesized by hydrolysis after reacting cellulose with acrylamide to obtain carbamoylethylcellulose. Further, Patent Document 2 discloses that cyanoethyl cellulose is obtained by addition reaction of acrylonitrile with cellulose, and then carboxymolyethyl cellulose is obtained by acid hydrolysis with hydrogen peroxide solution through carbamoylethyl cellulose. Has been. However, carboxyethyl cellulose and carbamoylethyl cellulose obtained by the methods disclosed in Patent Documents 1 and 2 have a low total substitution degree of carbamoylethyl group and carboxylethyl group of about 0.1, and do not exhibit water solubility.

Patent Document 3 discloses water-soluble carboxylethylcarbamoylethylcellulose having a carboxylethyl group and a carbamoylethyl group. However, in carboxylethylcarbamoylethylcellulose having a carbamoylethyl group, the polymer turns yellow over time. Further, the yellowing of the polymer changes the transparency of the aqueous solution, and worse, the water-solubility is not exhibited, or the performance of the product using the aqueous solution is remarkably impaired.
Patent Document 3 discloses that carboxylethylcarbamoylethylcellulose can be obtained by converting cellulose into an alkalicellulose and then reacting with acrylonitrile and adding water during the reaction. However, this method has a problem in that it is very difficult to control the substitution degree ratio between the carboxyethyl group and the carbamoylethyl group, and it is impossible to obtain carboxylethylcarbamoylethylcellulose having the same substitution degree ratio with good reproducibility. Furthermore, in this method, the utilization rate of acrylonitrile is as low as around 30%, and many by-products are generated at the same time. Therefore, repeated purification with an organic solvent is necessary, and the purity cannot be sufficiently increased, resulting in an increase in cost. Has drawbacks.

U.S. Pat. No. 2,338.681 (1944) US Pat. No. 2,820,691 (1959) Japanese Patent Laid-Open No. 60-044502

  An object of the present invention is to provide a water-soluble carboxyethyl cellulose which hardly contains a carbamoylethyl group and can be effectively used as a chemical product. Another object of the present invention is to provide an efficient method for producing carboxyethyl cellulose in which side reactions are suppressed.

As a result of diligent studies to achieve the above object, the present inventor reacted cellulose and acrylonitrile with an aqueous alkali solution having a specific concentration to cause hydrolysis, and further used the carbamoylethyl group by using a stirrer of a specific mode. The present inventors have found that carboxyethyl cellulose containing no hydrogen can be obtained with high efficiency and high purity, and based on this finding, the present invention has been completed.
That is, the present invention relates to a carboxyl ethyl cellulose having a carboxyl ethyl group substitution degree of 0.2 to 2.8, a carbamoyl ethyl group substitution degree of 0.04 or less, and a polymerization degree of 2 to 3000 carboxyl. It is related to ethyl cellulose.

  The carboxyl ethyl cellulose of the present invention has excellent whiteness and high product quality. In addition, there are few impurities, so stability and safety are high. In addition, the production method according to the present invention has a high raw material utilization rate, a one-step process, and simple purification.

In the carboxyethyl cellulose of the present invention, the degree of substitution of the carboxyethyl group needs to be in the range of 0.2 to 2.8. When the substitution degree of the carboxylethyl group is less than 0.2, the carboxylethylcellulose does not exhibit water solubility. On the other hand, when the degree of substitution of the carboxyethyl group exceeds 2.8, the transparency of the aqueous solution is significantly reduced. From the viewpoint of water solubility and the transparency of the aqueous solution, the carboxylethyl group is preferably from 0.3 to 2.7, and most preferably from 0.4 to 2.5. In addition, the carboxyethyl cellulose of the present invention needs to have a carbamoylethyl group of 0.04 or less. When the carbamoylethyl group exceeds 0.04, it turns yellow during storage in an aqueous solution. Preferably, the degree of substitution of the carbamoylethyl group is 0.03 or less, more preferably the degree of substitution of the carbamoylethyl group is 0.01 or less.
The degree of polymerization of the carboxyl ethyl cellulose of the present invention needs to be in the range of 2 to 3000 in order to exhibit mechanical properties as a molding material and coating strength when used as a coating material. Preferably it is 200-2500, More preferably, it is the range of 300-2000.

In the carboxylethyl cellulose of the present invention, the total amount of impurities selected from the group of acrylic acid, 2-cyanoethanol, 3-hydroxypropionic acid, 3-cyanoethyl ether, sodium chloride, sodium sulfate, and sodium acetate is based on the weight of the carboxylethyl cellulose. It is preferably 1000 ppm or less. When the total amount of impurities exceeds 1000 ppm, the thixotropic property of the aqueous solution necessary as a coating material is lost, and the bonding ability as an adhesive is reduced. Preferably, the total amount of impurities is 500 ppm or less, more preferably 200 ppm or less.
The carboxyl ethyl cellulose of the present invention is used in fields such as aqueous solution, film, fish feed, food, wall material composition, drilling stabilizer adjustment agent, cosmetics, pharmaceuticals, cleaning agent, paint, crosslinked polymer, superabsorbent resin, etc. However, the application is not limited to these fields.

The carboxyl ethyl cellulose of the present invention is not particularly limited, but includes the following steps (a) to (d), and in steps (c) and (d), (e) the stirring shaft rotates in a rotating and revolving manner. It can be manufactured by using a shaft kneader.
(A) An aqueous solution comprising an alkali metal hydroxide having an alkali concentration of 0.1 to 40 wt% is added to cellulose so that the amount is 1.2 to 50 times the weight of cellulose, and 0 to 80 ° C., 5 to Step of dipping for 120 minutes.
(B) The process of squeezing so that an alkaline aqueous solution may be 0.2 to 10 times the weight of cellulose.
(C) After adding acrylonitrile in an amount equivalent to 0.2 to 15 moles per glucose residue of cellulose to the alkali cellulose obtained in the step (b), the alkali cellulose and acrylonitrile are added at −30 to 50 ° C., A step of reacting for 350 hours to synthesize cyanoethyl cellulose.
(D) Without isolating the cyanoethyl cellulose of the above step (c), at a temperature of −30 to 30 ° C., water and an aqueous alkali solution were added to adjust the alkali concentration in the reaction system to 0.1 to 18 wt%. A step of alkali hydrolysis for 1 to 36 hours to convert to carboxyethyl cellulose.

The step (a) is an arserification step in which raw cellulose is immersed in an alkaline aqueous solution to perform arsellation to produce alkali cellulose.
The step (b) is a pressing step for controlling the amount of the aqueous alkali solution in the alkali cellulose obtained in the step (a) within a specific range with respect to the cellulose weight.
Step (c) is a cyanoethylation step in which acrylonitrile is added to the alkali cellulose of step (b) to produce cyanoethyl cellulose, and is represented by the following reaction formula (Formula 1).
The step (d) is a step of hydrolyzing the cyanoethyl cellulose in the step (c) to convert it to carboxyethyl cellulose, and is represented by the following reaction formula (Formula 2).

Hereinafter, the stirring requirements of steps (a) to (d) and (e) will be described in detail.
(A) Arcelization step The cellulose raw material used in the present invention may be natural cellulose such as cotton or wood, cotton linter, or regenerated cellulose or crystalline cellulose, depending on the necessity of the intended use, It can be selected appropriately.
The cellulose raw material to be used is preferably cut from 1 to 50 mm square by a pulverizer such as a rotary cutter from the viewpoint of enhancing the uniformity of the reaction.
The alkali concentration of the aqueous solution when cellulose is immersed in an aqueous solution made of an alkali metal hydroxide is in the range of 0.1 to 40 wt%. If the alkali concentration exceeds 40 wt%, the cellulose undergoes a depolymerization reaction, causing a significant decrease in the degree of polymerization, and carboxyethyl cellulose having the desired degree of polymerization cannot be obtained. On the other hand, if the alkali concentration is less than 0.1 wt%, the arseration does not proceed smoothly and the addition reaction of cellulose to acrylonitrile (formula 1) does not proceed. The alkali concentration is preferably 5 to 35 wt%, and more preferably 8 to 30 wt%.

Sodium hydroxide, potassium hydroxide, calcium hydroxide, lithium hydroxide, rubidium hydroxide and the like can be used as the alkali metal hydroxide used in the arserification step. Sodium hydroxide is preferred from the standpoint of salt removal efficiency.
When cellulose is immersed in an aqueous solution made of an alkali metal hydroxide (hereinafter abbreviated as “alkaline aqueous solution”), the amount of the alkaline aqueous solution is in the range of 1.2 to 50 times the weight of cellulose. When the amount of the aqueous alkali solution is less than 1.2 times, the arseration does not proceed smoothly, the addition reaction of acrylonitrile (Formula 1) to the cellulose does not proceed uniformly, and a large amount of unreacted cellulose remains. End up. If the amount exceeds 50 times, a large amount of impurities remain in the carboxyethyl cellulose, and the amount of impurities cannot be reduced to 1000 ppm or less even after repeated washing. The amount of the alkaline aqueous solution is preferably 1.5 to 45 times the amount of cellulose weight, more preferably 2 to 40 times the amount.
The immersion temperature is 0 to 80 ° C. When the temperature is lower than 0 ° C., the arseration does not proceed smoothly and the addition reaction of acrylonitrile to cellulose does not occur. When the temperature exceeds 80 ° C., a depolymerization reaction of cellulose occurs, and the degree of polymerization decreases. In order to promote the arserization smoothly and suppress the decrease in the degree of polymerization, 5 to 40 ° C. is preferable. The soaking time is determined by the alkali concentration of the alkali aqueous solution and the soaking temperature, but is 5 to 120 minutes from the uniformity and efficiency of the reaction.

(B) Pressing step After immersion in the aqueous alkali solution, pressing is performed using a press, a roller, or the like so that the amount of the aqueous alkali solution is 0.2 to 10 times the weight of the cellulose. When the amount exceeds 10 times, side reaction (Formula 3) of acrylonitrile and water and decyanoethylation reaction (Formula 4) from cyanoethyl cellulose, which is a reverse equilibrium reaction, are promoted, and carboxyethyl cellulose having the desired degree of substitution is obtained. In addition, the total amount of impurities contained in carboxyethyl cellulose exceeds 1000 ppm.
On the other hand, squeezing to less than 0.2 times is difficult in terms of machine operation. The amount of the alkaline aqueous solution after pressing is preferably 0.5 to 8 times the amount of cellulose and more preferably 0.8 to 6 times the range.

(C) Cyanoethylation step After transferring the alkali cellulose to a biaxial kneader described later in (e), 0.2 to 15 mol of acrylonitrile is added per glucose residue of cellulose. When adding acrylonitrile, the alkali cellulose is preferably in a stirred state in terms of uniformity. When the amount of acrylonitrile added is less than 0.2 mol per glucose residue, water-soluble carboxyethyl cellulose cannot be obtained. When the amount exceeds 15 mol, acrylonitrile self-polymerization and side reactions occur, and separation and purification of the obtained carboxyethyl cellulose is achieved. Becomes difficult. The amount of acrylonitrile added is preferably 0.3 to 10 mol, more preferably 0.4 to 5 mol, per glucose residue.

  Reacting alkali cellulose and acrylonitrile at a temperature of −30 to 50 ° C. for 2 to 350 hours is important from the viewpoint of suppressing the decyanoethylation reaction (Formula 4) and obtaining carboxylethylcellulose having the desired degree of substitution. is there. When the reaction temperature is less than −30 ° C., the alkaline aqueous solution is hardened and stirring is difficult mechanically. When the temperature exceeds 50 ° C., decyanoethylation from cyanoethyl cellulose is promoted, so that carboxyethyl cellulose having the desired degree of substitution cannot be obtained. When the reaction time is less than 2 hours, the cyanoethylation reaction is not sufficiently performed, and carboxyethyl cellulose having the desired degree of substitution cannot be obtained. Further, when the reaction is carried out over 350 hours, the transparency when the resulting carboxyl ethyl cellulose is made into an aqueous solution is remarkably lowered. From the viewpoint of controlling the degree of substitution, the reaction temperature is −20 to 40 ° C., the reaction time is 2 to 240 hours, more preferably −10 to 30 ° C., and the reaction time is 3 to 120 hours.

(D) Hydrolysis step The production method according to the present invention is characterized by suppressing decyanoethylation by adjusting the cyanoethyl cellulose synthesized in step (c) to a relatively low temperature and low alkali concentration without once isolating it. However, the cyanoethyl group is quantitatively hydrolyzed.
Once the isolated cyanoethyl cellulose is hydrolyzed, the decyanoethylation reaction proceeds simultaneously with the hydrolysis reaction even if the temperature in the reaction system is adjusted to -30 to 30 ° C and the alkali concentration is adjusted to 0.1 to 18 wt%. In addition to being unable to obtain carboxyethyl cellulose having the desired degree of substitution, the obtained carboxyethyl cellulose may not exhibit water solubility.

Next, it is necessary to adjust the temperature in the reaction system to −30 to 30 ° C. and the alkali concentration to 0.1 to 18 wt%. When the temperature in the reaction system is lower than −30 ° C., the hydrolysis reaction does not proceed sufficiently, and cyanoethyl group and carbamoylethyl group remain. When the temperature in the reaction system exceeds 30 ° C., decyanoethylation is promoted, and not only the target substitution degree of carboxylethylcellulose can be obtained, but also a large amount of acrylonitrile-derived by-product can be obtained. Separation and purification of ethyl cellulose becomes difficult. In this step, if the alkali concentration is less than 0.1 wt%, the hydrolysis reaction does not proceed sufficiently and cyanoethyl groups and carbamoylethyl groups remain. When the alkali concentration exceeds 18 wt%, the decyanoethylation reaction proceeds as the main reaction. Preferably, the reaction temperature is -20 to 20 ° C, the alkali concentration is 1 to 16 wt%, more preferably -10 to 10 ° C, and the alkali concentration is 5 to 15 wt%.
The reaction time in the hydrolysis is 1 to 36 hours after the addition of water. If the reaction time is less than 1 hour, the hydrolysis reaction does not proceed sufficiently and cyanoethyl group, carbamoylethyl group, and carboxylethyl group remain, and it is difficult to control the degree of substitution. Even if the reaction time is longer than 36 hours, the meaning is insignificant and inefficient. The reaction time is preferably 2 to 30 hours, more preferably 3 to 26 hours.

(E) Biaxial kneader It is necessary to use a biaxial kneader that rotates in a rotating and revolving manner in order to obtain the carboxyethyl cellulose of the present invention. In the case of using a uniaxial stirrer and a biaxial kneader, it is difficult to uniformly stir the reaction system, and the carbamoylethyl group generated as a reaction intermediate is not sufficiently hydrolyzed, and the degree of substitution is 0.04. It remains beyond. Moreover, it is difficult to control the side reaction, and a large amount of impurities remain.
The stirring speed needs to be 1 to 400 rpm for rotation and 2 to 450 rpm for revolution. When the rotation exceeds 400 rpm, and further, the revolution exceeds 450 rpm, the degree of polymerization decreases mechanochemically and carboxyethyl cellulose having the desired degree of polymerization cannot be obtained. The clearance between the rotary blade and the reactor wall needs to be 5 mm or less. If the thickness exceeds 5 mm, the reactant adheres to the reactor wall, and it is difficult to stir the reactant adhering to the wall. Therefore, carbamoylethyl groups partially remain, and the resulting carboxyl ethyl cellulose is made into an aqueous solution. Transparency in the case also decreases. The clearance is preferably 3 mm or less, more preferably 1 mm or less.
The carboxyethyl cellulose obtained by the method of the present invention is preferably neutralized and purified by the methods described in the following step (f) and step (g).

(F) The process of neutralizing the polymer after reaction in the range of pH 3-10 with an acid It is preferable from a viewpoint of the safety | security and stability of a product that the polymer after reaction is neutralized between pH 3-10 with an acid.
As the acid in the present invention, hydrochloric acid, sulfuric acid, acetic acid and the like can be used, but hydrochloric acid is preferred for economical reasons.
After the neutralization, the solid neutralized product is recovered by precipitating with a precipitating agent before performing the washing operation. As the precipitant in the present invention, methanol, ethanol, n-propanol, isopropyl alcohol, butanol, acetone, chloroform, hexane, ethyl acetate, ether and the like can be used, but methanol is preferable for economical reasons.

(G) The step of washing the neutralized product in the step (f) with a methanol aqueous solution having a water content of 5 to 50 wt%. The carboxyl ethyl cellulose after precipitation is washed with a methanol aqueous solution having a water content of 5 to 50 wt%. From the viewpoint of suppressing the total amount of impurities contained to 1000 ppm or less. When the water content of the aqueous methanol solution is less than 5%, the surface of the polymer is solidified, and impurities are taken into the polymer, making it impossible to reduce the impurity content to 1000 ppm or less. If the water content exceeds 50 wt%, carboxyethyl cellulose dissolves in the water-containing methanol, and the yield decreases. It is preferable to wash with a water content of 10 to 40% by weight of water-containing methanol, and more preferably with a water content of 15 to 30% by weight of water-containing methanol.
Since the recovered solid neutralized product contains an organic solvent, water, and the like, it is desirable to heat and dry under vacuum at 30 to 90 ° C. for 1 to 60 hours. If it is lower than 30 ° C., the organic solvent and water cannot be completely removed, and high purity carboxyethyl cellulose cannot be obtained. Above 90 ° C, it turns yellow and brown during drying. If the drying time is less than 1 hour, the organic solvent and water cannot be completely removed. Even if it exceeds 60 hours, there is no change in carboxyethyl cellulose, and it is uneconomical because it only takes energy. Therefore, the temperature is preferably 40 to 80 ° C. and the reaction time is 2 to 50 hours, more preferably 50 to 70 ° C. and the reaction time is 10 to 36 hours.

EXAMPLES Hereinafter, although an Example is given and it demonstrates in detail from this invention, of course, this invention is not limited at all by an Example etc. The main measurement values in the examples were measured by the following methods.
(1) Degree of substitution of carbamoylethyl group and carboxylethyl group A sample for substitution degree measurement was dissolved in heavy water to prepare a 3-5 wt% heavy aqueous solution, and FT-NMR (Avance, 400 MHz) manufactured by BRUKER was used. , Measured by ¹³ C-NMR, and the degree of substitution is based on the C1 peak of cellulose (106.32-104.2 ppm) area A, and the α carbon peak of the carbamoylethyl group (38.55-38.27 ppm). From the area B and the α-carbon peak (40.96 to 39.72 ppm) of the carboxyethyl group, the area C was calculated as follows.
Total degree of substitution = B / A (degree of substitution of carbamoylethyl group) + C / A (degree of substitution of carboxylethyl group) (1)
In addition, when a carbamoylethyl group is not detected by the above analysis, measurement is performed using FT-IR-6200 manufactured by JASCO, and it is confirmed that a peak of absorption 3300-3200 cm ⁻¹ based on the carbamoylethyl group is not detected. To do.

(2) Method for measuring degree of polymerization of carboxyethyl cellulose 0.005-0.010 g of carboxyethyl cellulose was dissolved in 10 ml of water and measured using GPC (SIL-20A) manufactured by Shimadzu Corporation. The measurement conditions are as follows.
Column: OHpak, SB-806MHQ
Detection method: RI
Column temperature: 40 ° C
Flow rate: 1.0 ml / min Injection amount: 0.3 ml
Based on the molecular weight distribution thus measured, the weight average molecular weight c is determined, the molecular weight d of glucose units is calculated from the degree of substitution determined by the above formula (1), and the degree of polymerization e is further calculated based on the following formula (2). Was calculated.
e = c / d (2)

(3) Measuring method of b * value of polymer The polymer powder is filled in a glass cell (inner diameter 61 mm, depth 30 mm) to 90 to 100% of the depth, and the color difference system (SM The b * value was measured using -7-CH).
(4) Calculation method of acrylonitrile utilization rate
The utilization rate x of acrylonitrile was calculated by the method shown below, where a is the degree of substitution determined above and b is the molar ratio of the acrylonitrile used to the glucose residue of cellulose.
Utilization rate x = a / b
(5) Viscosity measuring method of 2 wt% aqueous solution In the 2 wt% viscosity measuring method, 1.0 g of a sample is completely dissolved in 50 g of pure water until no residue remains, and then a HAAKE-made visco tester (VT6 plus) is used. The viscosity was measured.

(6) Measuring method of each content of acrylic acid, 2-cyanoethanol, 3-hydroxypropionic acid, 3-cyanoethyl ether Measurement of acrylic acid, 2-cyanoethanol, 3-hydroxypropionic acid, 3-cyanoethyl ether A gas chromatograph (GC-2010) manufactured by Shimadzu Corporation was used. The measurement conditions are as follows. As the measurement sample solution, a 0.5 wt% aqueous solution prepared by dissolving the obtained carboxyl ethyl cellulose in water was used.
Column: Gasclo pack 56, 86-100 mesh
Detection method: FID
Injection volume: 2 μl
Column temperature: 170 ° C
Injection port temperature: 200 ° C
Helium flow rate: 40 ml / min
Gas pressure (H ₂ ): 0.63 kg / cm ³
Gas pressure (air): 0.50 kg / cm ³
(7) Method for measuring sodium chloride content The sodium chloride content was measured by ion chromatography using an element analyzer manufactured by Dionex.

[Example 1]
Cotton linters having a polymerization degree of 1300 were pulverized to about 1 to 5 mm square using a pulverizer (model: ACM pulverizer) manufactured by Hosokawa Micron Corporation, vacuum-dried at 70 ° C. for 12 hours, 10 g collected, and 15 wt% water It was immersed in 100 g of an aqueous sodium oxide solution at 30 ° C. for 30 minutes. Squeeze until the weight of the aqueous alkali solution becomes 5 times the weight of cellulose, add 1.0 mol of acrylonitrile per glucose residue of cellulose, and rotate using a biaxial kneader (clearance: 4 mm) manufactured by Primix. The mixture was stirred at 50 rpm, revolution 35 rpm, and 0 ° C. for 24 hours. Thereafter, 25 g of pure water was added to adjust the alkali concentration in the reaction system to 10 wt%, and the mixture was kneaded at 30 ° C. for 16 hours, neutralized to pH 8.4 with 6N hydrochloric acid, and washed with a 20 wt% aqueous methanol solution. And recovered.
The reaction product obtained here was dried in a vacuum dryer at 70 ° C. for 36 hours to obtain carboxyethyl cellulose. The degree of substitution of the carboxyethyl group was 0.93, and no carbamoylethyl group was detected. In addition, the cyanoethyl group was not detected from the infrared absorption spectrum. Moreover, this carboxyl ethyl cellulose showed water solubility, and b * value was 3. The viscosity of this 2 wt% aqueous solution of carboxyl ethyl cellulose was 1360 mPa · s.

[Examples 2 to 5]
Carboxyl ertil cellulose was synthesized and recovered under the same conditions as in Example 1 except that pulp having a polymerization degree of 200 to 1800 was used as a raw material. Any carboxyethyl cellulose satisfied the scope of the present invention.
[Examples 6 to 8]
Carboxyethyl cellulose was synthesized and recovered under the same conditions as in Example 1 except that an aqueous sodium hydroxide solution having an alkali concentration of 0.1 to 30 wt% with respect to cellulose was added in the alkali soaking step. Any carboxyethyl cellulose satisfied the scope of the present invention.

[Examples 9 to 11]
Carboxyethyl cellulose was synthesized and recovered under the same conditions as in Example 1 except that in the alkali pressing step, pressing was performed until the weight of the aqueous alkaline solution became 0.2 to 10 times the weight of the cellulose. Any carboxyethyl cellulose satisfied the scope of the present invention.
[Examples 12 to 18]
Carboxyethyl cellulose was synthesized and recovered under the same conditions as in Example 1 except that the amount of acrylonitrile added and the reaction temperature in the cyanoethylation step were adjusted under the conditions shown in Tables 1-1 to 1-3. Any carboxyethyl cellulose satisfied the scope of the present invention.
[Examples 19 to 22]
Carboxyethyl cellulose was synthesized under the same conditions as in Example 1 except that the concentration of sodium hydroxide aqueous solution in the hydrolysis step, the reaction temperature, and the reaction time were adjusted under the conditions shown in Table 1-1 to Table 1-3. Recovered. Any carboxyethyl cellulose satisfied the scope of the present invention.

[Comparative Example 1]
A cotton linter having a polymerization degree of 1300 was pulverized in the same manner as in Example 1 and synthesized under the same conditions using a uniaxial stirrer. The polymer obtained here was dried in a vacuum dryer at 70 ° C. for 36 hours, Carboxyethyl cellulose was obtained. The degree of substitution, acrylonitrile utilization and viscosity, and impurity content of the obtained carboxyl ethyl cellulose are shown in Table 1-1 to Table 1-3 and Table 2. Although carboxyethyl cellulose was obtained, the carbamoylethyl group remained and was outside the scope of the present invention.
[Comparative Example 2]
Cotton linters having a polymerization degree of 1300 were pulverized in the same manner as in Example 1, synthesized using a kneader under exactly the same conditions, washed and dried in the same manner as in Comparative Example 1 to obtain carboxyethyl cellulose. The degree of substitution, acrylonitrile utilization and viscosity, and impurity content of the obtained carboxyl ethyl cellulose are shown in Table 1-1 to Table 1-3 and Table 2. Although carboxyethyl cellulose was obtained, the carbamoylethyl group remained and was outside the scope of the present invention.

[Comparative Examples 3 to 10]
Example 1 except that the reaction temperature in the cyanoethylation step and the concentration and reaction temperature of the aqueous sodium hydroxide solution in the reaction system in the hydrolysis step were adjusted under the conditions shown in Table 1-1 to Table 1-3. Under the same conditions, carboxyethyl cellulose was synthesized and recovered. All samples were outside the scope of the present invention.
[Comparative Examples 11-12]
Cotton linters having a polymerization degree of 1300 were pulverized in the same manner as in Example 1, and carboxyethyl cellulose was synthesized under the same conditions, and washed with a 3 wt% aqueous methanol solution (Comparative Example 11) and methanol (Comparative Example 12). The obtained polymer was dried in a vacuum dryer at 70 ° C. for 36 hours to obtain carboxyethyl cellulose. The impurity content of the obtained carboxyethyl cellulose is shown in Table 2. Although water-soluble carboxyethyl cellulose was obtained, the impurity content exceeded the scope of the present invention.

  The carboxyl ethyl cellulose of the present invention is used in fields such as aqueous solution, film, fish feed, food, wall material composition, drilling stabilizer adjustment agent, cosmetics, pharmaceuticals, cleaning agents, paints, crosslinked polymers, and superabsorbent resins. Can be used for

Claims (16)

  A carboxylethyl cellulose having a carboxylethyl group substitution degree of 0.2 to 2.8, a carbamoylethyl group substitution degree of 0.04 or less, and a polymerization degree of 2 to 3000.   The carboxyl ethyl cellulose according to claim 1, wherein the b * value of the carboxyl ethyl cellulose polymer is 15 or less.   The total amount of impurities selected from the group consisting of acrylic acid, 2-cyanoethanol, 3-hydroxypropionic acid, 3-cyanoethyl ether, sodium chloride, sodium sulfate, and sodium acetate is 1000 ppm or less based on the weight of carboxyethyl cellulose. The carboxyethyl cellulose according to claim 1 or 2. The method includes the following steps (a) to (d), and in steps (c) and (d), (e) a biaxial kneader in which a stirring shaft rotates in a rotating and revolving manner is used. Item 4. A method for producing carboxylethyl cellulose according to any one of Items 1 to 3.
(A) An alkali metal hydroxide aqueous solution having an alkali concentration of 0.1 to 40 wt% is added to cellulose in an amount of 1.2 to 50 times the weight of cellulose, and immersed in 0 to 80 ° C. for 5 to 120 minutes. Process.
(B) The process of squeezing so that an alkaline aqueous solution may be 0.2 to 10 times the weight of cellulose.
(C) After adding acrylonitrile to the cellulose obtained in the above step (b) in an amount corresponding to 0.2 to 15 mol per glucose residue of cellulose, alkali cellulose and acrylonitrile are added at -30 to 50 ° C and 2 to 350, respectively. A step of synthesizing cyanoethyl cellulose by reacting for a period of time.
(D) Without isolating the cyanoethyl cellulose of the above step (c), at a temperature of −30 to 30 ° C., water and an aqueous alkaline solution were added to adjust the alkali concentration in the reaction system to 0.1 to 18 wt%. A step of alkali hydrolysis for 1 to 36 hours to convert to carboxyethyl cellulose.   The stirring mode is a rotating and revolving type, the stirring speed is 1 to 400 rpm, the rotating speed is 2 to 450 rpm, and the clearance between the rotary blade and the reactor wall is 5 mm or less, and stirring is performed using a twin-screw kneader. The method for producing carboxyethyl cellulose according to claim 4, wherein 6. The method for producing carboxyethyl cellulose according to claim 4 or 5, comprising the following post-treatment steps (f) and (g).
(F) The process of neutralizing the carboxyl ethyl cellulose after reaction in the range of pH 3-10 with an acid.
(G) A step of washing the neutralized product in the step (f) with a methanol aqueous solution having a water content of 5 to 50 wt%.   An aqueous solution containing 0.1 to 60 wt% of the carboxyethyl cellulose according to any one of claims 1 to 3.   The film which contains 0.1-99 wt% of carboxyethylcellulose in any one of Claims 1-3.   The feed for fish farming which contains 20-90 wt% of carboxyethylcellulose in any one of Claims 1-3.   The foodstuff which contains 0.1-60 wt% of carboxyethylcellulose in any one of Claims 1-3.   A wall material composition containing 20 to 90 wt% of the carboxyethyl cellulose according to claim 1.   The adjustment agent for excavation stabilization liquid containing 1-90 wt% of carboxyethylcellulose in any one of Claims 1-3.   Cosmetics containing 0.1 to 60 wt% of the carboxyethyl cellulose according to any one of claims 1 to 3.   The pharmaceutical which contains 0.1-30 wt% of carboxyethylcellulose in any one of Claims 1-3.   A cleaning agent containing 0.01 to 90 wt% of the carboxyethyl cellulose according to any one of claims 1 to 3.   The coating material containing 0.1-80 wt% of carboxyethylcellulose in any one of Claims 1-3.