JP5889012B2 - Method for producing carboxymethylcellulose - Google Patents

Description

  The present invention relates to a method for producing carboxymethyl cellulose. Specifically, the present invention relates to a method for efficiently producing carboxymethyl cellulose having a high transparency of an aqueous solution.

  Carboxymethylcellulose (hereinafter also referred to as “CMC”) is widely used as a thickener, a dispersant, an emulsifier, a protective colloid agent, a stabilizer, and the like. As a method for producing CMC, a solvent method is known in which cellulose is dispersed in a water-containing organic solvent, an alkali is allowed to act thereon to prepare alkali cellulose, and then monohaloacetic acid is added to perform an etherification reaction.

For example, Patent Document 1 discloses a carboxymethyl cellulose alkali metal salt in which cellulose is converted to alkali cellulose by reaction with an alkali metal hydroxide in a mixed medium of an organic solvent and water, and is etherified with monochloroacetic acid or a salt thereof. A method for producing a carboxymethyl cellulose alkali metal salt is disclosed in which arseration is performed at an organic solvent concentration of 70 to 84% by weight and then etherification is performed at an organic solvent concentration of 88 to 92% by weight. ing.
Patent Document 2 discloses a method for producing a carboxymethyl cellulose salt, which uses a water-containing organic solvent 21 times by weight or more of cellulose as a reaction solvent, and uses sodium monochloroacetate in the presence of alkali to react in a slurry state. A method for producing methylcellulose salt is disclosed.
Patent Document 3 discloses a method for producing a cellulose ether derivative in which a low crystalline powdery cellulose having a crystallinity of 50% or less is reacted with an organic halide compound in the presence of a base.

Japanese Examined Patent Publication No. 6-55762 Japanese Patent Publication No.53-29357 International Publication No. 2009/063856

However, the methods disclosed in Patent Documents 1 and 2 have a problem in that the amount of solvent used is large and the purification load such as removal of the solvent by distillation is large.
In the method disclosed in Patent Document 3, powdered cellulose is stirred with sodium chloroacetate and then heated to 50 ° C., and then a 48 wt% aqueous sodium hydroxide solution is added (Example 1-1). 1-2, and Comparative Example 1-1). Therefore, the reaction between cellulose and sodium chloroacetate proceeds locally, carboxymethyl groups are introduced heterogeneously into the cellulose chain, and the aqueous solution has high transparency. As a dispersant or protective colloid agent added to cosmetics and foods It is difficult to produce useful carboxymethylcellulose.

  An object of the present invention is to provide a method for efficiently producing carboxymethyl cellulose having a high transparency of an aqueous solution.

The present inventor added monohaloacetic acid or a salt thereof at −10 to 10 ° C. after mixing the cellulose and the alkali agent, and then heated to 40 to 100 ° C. to cause the reaction to dissolve in water. It has been found that carboxymethyl cellulose having high transparency of an aqueous solution can be produced efficiently and simply.
In the present invention, after mixing cellulose and an alkaline agent, monohaloacetic acid or a salt thereof is added at −10 to 10 ° C., and then heated to 40 to 100 ° C. to react cellulose with monohaloacetic acid or a salt thereof. A method for producing carboxymethyl cellulose is provided.

  According to the method of the present invention, carboxymethyl cellulose having a high transparency of an aqueous solution can be efficiently produced.

In the present invention, after mixing cellulose and an alkaline agent, monohaloacetic acid or a salt thereof is added at −10 to 10 ° C., and then heated to 40 to 100 ° C. to react cellulose with monohaloacetic acid or a salt thereof. , A method for producing carboxymethylcellulose.
After mixing the cellulose and the alkali agent, the addition of monohaloacetic acid or a salt thereof is performed at −10 to 10 ° C., so that the heat of neutralization due to the neutralization reaction of the monohaloacetic acid with the alkali agent, It is considered that carboxymethylcellulose with high transparency of the aqueous solution can be formed by suppressing the progress of the local carboxymethylation reaction due to heat of mixing and the like, and introducing the substituents more uniformly into the cellulose chain.

[material]
(cellulose)
In the present invention, monohaloacetic acid or a salt thereof is reacted with cellulose. In actual production, not only cellulose but also a cellulose-containing material can be used.
Although there is no restriction | limiting in particular as a cellulose containing material used for this invention, From the viewpoint of cellulose purity and availability, wood pulp, such as N material pulp which mainly consists of softwood materials, and L material pulp which mainly consists of hardwood materials Pulp such as cotton linter pulp obtained from fibers around cotton seeds is preferred.
Although the magnitude | size of the cellulose used for this invention and a cellulose containing material is not specifically limited, From a reactive viewpoint of a cellulose, an average particle diameter of 500 micrometers or less is preferable and 300 micrometers or less are more preferable. The particle size can be adjusted with an unsieved product using a sieve having the above particle size.
The water content in the cellulose and cellulose-containing material is preferably 10% by mass or less, more preferably 5% by mass or less, and still more preferably 3% by mass or less from the viewpoint of handleability. The lower limit is 0% by mass.
The average degree of polymerization of the cellulose used in the present invention is not particularly limited. From the viewpoint of the transparency of the aqueous solution, it is preferably 100 to 2000, more preferably 100 to 1000. In the present invention, the average degree of polymerization means a viscosity average degree of polymerization measured by a copper-ammonia method, and is specifically calculated by the method described in Examples.

Several crystal structures are known for cellulose, and the degree of crystallinity is generally calculated from the ratio of crystal parts to the total amount of amorphous parts and crystal parts.
In the present invention, “crystallinity” means type I crystallinity derived from the crystal structure of natural cellulose, and is calculated by the Segal method from the diffraction intensity value by the powder X-ray crystal diffraction spectrum method. , Defined by the following formula (1).
Cellulose type I crystallinity (%) = [(I _22.6 -I _18.5 ) / I _22.6 ] × 100 (1)
Wherein, I _22.6 represents the diffraction intensity of the lattice plane (002 plane) (diffraction angle 2 [Theta] = 22.6 °) in the X-ray diffraction, and I _18.5 is amorphous portion (angle of diffraction 2 [Theta] = 18.5 ° ) Shows the diffraction intensity. ]
The crystallinity of the cellulose used in the present invention is not particularly limited. In the method of the present invention, for example, any of crystalline cellulose having a crystallinity of more than 50% and low-crystalline cellulose having a crystallinity of 50% or less. Can also be used. From the viewpoint of easy availability, it is preferable to use crystalline cellulose.
The crystallinity of the crystalline cellulose is preferably more than 50% and 95% or less, more preferably 60 to 95%, still more preferably 70 to 95%, and still more preferably 75 to 95%.
As a commercial item of crystalline cellulose, trade name: KC Flock manufactured by Nippon Paper Chemicals Co., Ltd., trade name: Theolas manufactured by Asahi Kasei Chemicals Co., Ltd., and the like can be given.

(Alkaline agent)
As the alkali agent used in the present invention, an alkali metal hydroxide or an alkaline earth metal hydroxide is preferable because it efficiently alcoholates the hydroxyl group of the cellulose molecule. Specific examples of the alkali metal hydroxide include sodium hydroxide, potassium hydroxide, lithium hydroxide and the like, and specific examples of the alkaline earth metal hydroxide include magnesium hydroxide and calcium hydroxide. Among these, Preferably it is an alkali metal hydroxide, More preferably, it is sodium hydroxide or potassium hydroxide, More preferably, it is sodium hydroxide.

  When a monohaloacetic acid salt is used as monohaloacetic acid or a salt thereof, the equivalent ratio of the alkali agent to the anhydroglucose unit of the cellulose used in the present invention (alkali agent / anhydrous glucose unit) is determined by the water solubility of CMC and the transparency of the CMC aqueous solution. From the reason of exhibiting sex, it is preferably 0.3 to 3, more preferably 0.5 to 2, and still more preferably 0.5 to 1.6. The number of moles of anhydroglucose units can be determined as a value obtained by dividing the weight of cellulose by the molecular weight 162 of anhydroglucose units.

  When monohaloacetic acid or a salt thereof is used as monohaloacetic acid, the alkaline agent is consumed for neutralization of monohaloacetic acid. Therefore, the equivalent ratio of the alkaline agent to the anhydrous glucose unit of cellulose used in the present invention (alkaline agent / anhydroglucose unit) ) Is preferably from 0.6 to 6, more preferably from 1.0 to 4, and even more preferably from 1 to 3.2 from the viewpoint of expressing the water solubility of CMC and the transparency of the aqueous solution of CMC.

  Although there is no particular limitation on the method of mixing cellulose and an alkali agent, a method of adding an alkali agent to cellulose in the presence of water described later is preferable. Alkaline agents may be added all at once or dividedly. When adding all at once, from the viewpoint of uniformly dispersing the alkali agent in the cellulose, it is preferable to add the alkali agent to the cellulose and then stir and mix, or add and mix the alkali agent while stirring the cellulose. In the case of adding in a divided manner, a method of adding an aqueous solution of an alkaline agent dropwise is preferable, and the dropping time is preferably 0.5 to 10 hours, more preferably 0.5 to 5 hours, and still more preferably 1 ~ 3 hours.

(Monohaloacetic acid or its salt)
The halogen atom in the monohaloacetic acid used in the present invention is preferably an iodine atom, a bromine atom or a chlorine atom, more preferably a bromine atom or a chlorine atom, still more preferably chlorine, for reasons of reactivity, versatility and ease of handling. Is an atom.
The metal capable of forming a salt with monohaloacetic acid is preferably lithium, potassium or sodium, more preferably potassium or sodium, still more preferably sodium, from the viewpoint of the water solubility of the resulting carboxymethyl cellulose and the transparency of the aqueous solution. .
Specific examples of monohaloacetic acid or a salt thereof used in the present invention include monochloroacetic acid, monobromoacetic acid, sodium monochloroacetate, potassium monochloroacetate and the like, and monochloroacetic acid or sodium monochloroacetate is preferable.

Monohaloacetic acid or a salt thereof is added to the mixture of cellulose and alkaline agent. Monohaloacetic acid or a salt thereof may be added as a solid (powder) or may be added after being dissolved in an organic solvent described later. Moreover, it is preferable to add monohaloacetic acid or its salt to the mixture of a cellulose and an alkaline agent over time. In the method of the present invention, when monohaloacetic acid or a salt thereof is added, it is added at −10 to 10 ° C. in order to suppress local progress of the reaction due to generation of heat of mixing or heat of neutralization. However, rapid heat generation can be suppressed by adding over time. For example, when adding monohaloacetic acid or a salt thereof dissolved in an organic solvent described later, a method of adding by dropwise addition is preferred, and the dropping time is preferably 0.5 to 10 hours, more preferably 0.5 to 5 hours, more preferably 1 to 3 hours.
Stir the obtained cellulose, alkali agent and monohaloacetic acid or its salt mixture within the above temperature range for about 5 minutes to 3 hours from the viewpoint of suppressing local progress of the reaction after completion of dropping. Is preferred.

The molar ratio of monohaloacetic acid or a salt thereof to anhydroglucose unit of cellulose used in the present invention (monohaloacetic acid or a salt thereof / anhydroglucose unit) is the reason for expressing the water solubility of CMC and the transparency of an aqueous solution of CMC. Preferably it is 0.3-3, More preferably, it is 0.5-2.0, More preferably, it is 0.5-1.6.
Said monohaloacetic acid or its salt, and an alkali agent can be used individually or in combination of 2 types or more, respectively.

The equivalent ratio of the alkali agent to the monohaloacetic acid used in the present invention (alkali agent / monohaloacetic acid) is preferably 2-3, more preferably 2-2. 5, More preferably, it is 2-2.2, More preferably, it is 2-2.1.
In the case of using a monohaloacetate, the equivalent ratio of the alkali agent to the monohaloacetate used in the present invention (alkali agent / monohaloacetate) is preferable because the reaction is efficiently performed while suppressing side reactions. Is 1 to 2, more preferably 1 to 1.5, still more preferably 1 to 1.1, and still more preferably 1 to 1.05.

In the method of the present invention, monohaloacetic acid or a salt thereof is added to a mixture of cellulose and an alkaline agent at −10 to 10 ° C.
The temperature at the time of addition of the monohaloacetic acid or its salt in this invention is -10-10 degreeC. If the temperature at the time of addition of monohaloacetic acid or a salt thereof is −10 ° C. or higher, the energy required for cooling can be reduced, and if it is 10 ° C. or lower, the reaction occurs locally due to generation of heat of mixing or heat of neutralization. Can be suppressed, and the transparency of the obtained CMC aqueous solution can be expressed. From the above viewpoint, the temperature at the time of addition of monohaloacetic acid or a salt thereof is preferably −5 to 10 ° C., more preferably −5 to 5 ° C., and further preferably 0 to 5 ° C.
There is no limitation on the cooling time for adding the monohaloacetic acid or its salt at the above temperature, and the cellulose and the alkali agent may be mixed before mixing, or the cellulose and the alkali agent may be mixed or after mixing. However, from the viewpoint of equipment load, it is preferable to carry out the mixing of the cellulose and the alkaline agent or after the mixing.

(water)
The mixing of the cellulose and the alkali agent is preferably performed in the presence of water, because the alkali agent efficiently converts the hydroxyl group of the cellulose molecule into an alcoholate. Although water may be added alone, for example, when mixing cellulose and an alkaline agent, water can be added by adding the alkaline agent as an aqueous solution.
From the viewpoint of efficiently alcoholating the hydroxyl group of the cellulose molecule, the water content during mixing of cellulose and the alkali agent is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, and 60 masses. Part or less is more preferable. Moreover, 20 mass parts or more are preferable from a viewpoint of making it alcoholate efficiently. By making the water content at the time of mixing the alkali agent within the above range, the hydroxyl group of the cellulose molecule can be efficiently alcoholated. From the above viewpoint, the water content when mixing the cellulose and the alkali agent is preferably 20 to 100 parts by mass, more preferably 20 to 80 parts by mass, and still more preferably 20 to 60 parts by mass with respect to 100 parts by mass of cellulose.

The water content during the reaction is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, and even more preferably 60 parts by mass or less with respect to 100 parts by mass of cellulose, from the viewpoint of enhancing the dispersibility of cellulose and the reactivity of cellulose. Moreover, 20 mass parts or more are preferable from the reactive viewpoint of a cellulose. By setting the water content during the reaction in the above range, aggregation of cellulose can be suppressed, the reaction can be efficiently advanced while maintaining a good powder state, and the handleability of the product is excellent. From the above viewpoint, the water content during the reaction is preferably 20 to 100 parts by mass, more preferably 20 to 80 parts by mass, and still more preferably 20 to 60 parts by mass with respect to 100 parts by mass of cellulose.
Although dehydration can be carried out after mixing of the alkali agent or after addition of monohaloacetic acid or a salt thereof, it is preferable that the reaction is carried out as it is without dehydration because the operation is simple.

(Organic solvent)
In the production method of the present invention, it is preferable to react cellulose with monohaloacetic acid or a salt thereof in the presence of an organic solvent from the viewpoint of improving the transparency of the aqueous solution of carboxymethylcellulose obtained.
The amount of the organic solvent during the reaction is preferably 30 to 300 parts by mass, more preferably 30 to 200 parts by mass, and still more preferably from the viewpoint of increasing the transparency of the aqueous solution of carboxymethylcellulose. Is 40 to 170 parts by mass, more preferably 50 to 150 parts by mass. When the amount of the organic solvent during the reaction is 300 parts by mass or less, the aggregation of cellulose is suppressed and the carboxymethylation reaction proceeds uniformly. Moreover, if the amount of the organic solvent at the time of reaction is 200 mass parts or less, coloring of the obtained carboxymethylcellulose will be suppressed. This is considered to be because when the amount of the solvent is large, the reaction system becomes dilute, and the contact time between the cellulose and the produced carboxymethyl cellulose and the alkali agent becomes long due to the decrease in the reaction rate, and coloration is likely to occur. On the other hand, if the amount of the organic solvent during the reaction is 30 parts by mass or more, the mixing property between cellulose and monohaloacetic acid or a salt thereof can be improved.
By setting the amount of the organic solvent during the reaction within the above range, aggregation of cellulose can be suppressed, the reaction can proceed while maintaining a good powder state, carboxy having good color quality and high aqueous transparency. Methylcellulose is obtained.

The organic solvent is preferably one that dissolves 100 g or more in 100 g of water at 25 ° C. from the viewpoint of uniform reactivity of monohaloacetic acid or a salt thereof.
The organic solvent that can be used in the method of the present invention is preferably a lower alcohol such as methanol, ethanol, n-propanol, isopropanol, n-butanol, or tert-butanol; a ketone solvent such as acetone or methyl ethyl ketone; acetonitrile, dimethyl Sulphoxide and the like, more preferably methanol, isopropanol, and acetone, and still more preferably isopropanol and acetone.
Said organic solvent can be used individually or in combination of 2 or more types.
Moreover, said organic solvent can be used in mixture with water.

  Although there is no limitation in the addition time of an organic solvent, the transparency of the aqueous solution of the obtained carboxymethylcellulose will become higher when an alkali agent is mixed after mixing a cellulose and an organic solvent. This is because the organic solvent allows the alkaline agent to penetrate more uniformly into the cellulose, so that the substituent is introduced more uniformly into the cellulose chain during the reaction with monohaloacetic acid or a salt thereof. As a result, the transparency of the obtained aqueous solution of carboxymethyl cellulose is considered to be high.

[Reaction conditions]
In the method of the present invention, monohaloacetic acid or a salt thereof is added to a mixture of cellulose and an alkali agent, and then heated to 40 to 100 ° C. to react the cellulose with the monohaloacetic acid or a salt thereof to obtain carboxymethylcellulose. obtain.
The reaction temperature is usually 40 to 100 ° C., preferably 40 to 80 ° C., more preferably 50 to 70 ° C., from the viewpoint of efficiently allowing the reaction to proceed while suppressing side reactions.
At the time of reaction, it is preferable to stir from the viewpoint of improving the dispersibility of cellulose and mixing the cellulose, the alkali agent, and the monohaloacetic acid or a salt thereof, and the peripheral speed of the stirring blade during stirring is preferably 0.003. It is -1.5m / s, More preferably, it is 0.006-0.6m / s, More preferably, it is 0.015-0.3m / s.
Although reaction time is based also on reaction temperature, Preferably it is 1 to 10 hours, More preferably, it is 2 to 8 hours.
The end point of the reaction can be taken as a standard when 95% by mass or more of the addition amount of monohaloacetic acid or a salt thereof has been consumed. The residual amount of monohaloacetic acid or a salt thereof can be confirmed by high performance liquid chromatography (HPLC) or the like.
From the viewpoint of suppressing coloring of the obtained carboxymethyl cellulose, it is preferable to perform the operation from the mixing of the cellulose and the alkali agent to the reaction in the presence of an inert gas such as nitrogen.
After completion of the reaction, the resulting product is stirred with an aqueous solution of a hydrophilic solvent such as methanol and then filtered to remove salts such as sodium chloride generated by the reaction. Further, the filter cake can be efficiently dehydrated by washing with acetone or the like.

[Carboxymethylcellulose]
By the production method of the present invention, carboxymethyl cellulose having a high transparency of the aqueous solution is obtained. A part or all of the carboxy group of the obtained carboxymethyl cellulose may be a salt, and the element serving as a counter ion is preferably an alkali metal such as sodium, potassium or lithium or an alkaline earth metal such as magnesium or calcium. Alkali metals are more preferable, sodium and potassium are more preferable, and sodium is still more preferable.

The transmittance of a 1% by mass aqueous solution of carboxymethylcellulose obtained by the method of the present invention at an optical path length of 1 cm and a wavelength of 600 nm is preferably 90% or more from the viewpoint of expressing transparency and improving the appearance of the blended product. More preferably, it is 92% or more, more preferably 95% or more, and still more preferably 98% or more. The method for measuring the transmittance of an aqueous solution of CMC is as described in Examples described later.
Since the carboxymethyl cellulose obtained by the method of the present invention has high transparency of an aqueous solution, it is useful as a dispersant or protective colloid agent for cosmetics and foods.

The measurement of the crystallinity, the degree of polymerization and the water content of the cellulose used as a raw material , and the degree of substitution of the carboxyl group of the carboxymethylcellulose obtained in Examples , Reference Examples and Comparative Examples, the transmittance of the aqueous solution and the degree of coloration The following method was used. In the following Examples and Comparative Examples, “%” is “mass%” and “parts” is “parts by mass” unless otherwise specified.
(1) Calculation of crystallinity Cellulose type I crystallinity is measured by using the “Rigaku RINT 2500VC X-RAY diffractometer” (trade name) manufactured by Rigaku Corporation under the following conditions. And it computed based on the said Formula (1).
Measurement conditions, X-rays _source: Cu / K α -radiation, tube voltage: 40 kV, tube current: 120 mA, measuring range: measured at a diffraction angle 2θ = 5~45 °. The measurement sample was prepared by compressing a pellet having an area of 320 mm ² × thickness of 1 mm. The X-ray scan speed was measured at 10 ° / min.

(2) Measurement of average degree of polymerization (copper-ammonia method)
((I) Preparation of measurement solution)
After adding 0.5 g of cuprous chloride and 20-30 mL of 25% aqueous ammonia to a volumetric flask (100 mL) and completely dissolving, add 1.0 g of cupric hydroxide and 25% aqueous ammonia, and add a volumetric flask. The amount up to one inch before the marked line. This was stirred for 30-40 minutes to completely dissolve. Then, precisely weighed pulp cellulose (or cellulose-containing material) (dried under reduced pressure at 105 ° C. and 20 kPa for 12 hours) was added, and the ammonia water was filled up to the marked line of the volumetric flask. It sealed so that air might not enter, and it stirred with the magnetic stirrer for 12 hours, and melt | dissolved. The amount of pulp cellulose added in the same manner was changed in the range of 20 to 500 mg to prepare measurement solutions having different concentrations.

((Ii) Measurement of viscosity average degree of polymerization)
Put the measurement solution (copper ammonia aqueous solution) obtained in (i) above into an Ubbelohde viscometer and let it stand in a constant temperature bath (20 people 0.1 ° C) for 1 hour, then measure the flow rate of the liquid. did. From the flow time (t (second)) of the copper ammonia solution having various pulp cellulose concentrations (g / dL) and the flow time (t ₀ (second)) of the copper ammonia solution without addition of pulp cellulose, The reduced viscosity (η _sp / c) at the concentration was determined from the following equation.
η _sp / c = (t / t ₀ −1) / c
(Where c is the pulp cellulose concentration (g / dL))
Further, the reduced viscosity was extrapolated to c = 0 to determine the intrinsic viscosity [η] (dL / g), and the viscosity average degree of polymerization (DP _v ) was determined from the following equation.
DP _v = 2000 × [η]
(In the formula, 2000 is a coefficient specific to cellulose.)

(3) Measurement of moisture content The moisture content was measured at 150 ° C using a halogen moisture meter (trade name: “HG53” manufactured by METTLER TOLEDO CO., LTD.). A 2 g sample was used, and the point at which the weight change rate for 50 seconds was 1 mg or less was taken as the end point of the measurement.

(4) Measurement of degree of substitution of carboxy group In the present invention, the degree of substitution refers to the average number of moles of carboxymethyl groups present in the CMC molecule per mole of anhydroglucose units constituting the cellulose main chain.
Since all the carboxy groups of the carboxymethylcellulose obtained in the examples are considered to be sodium salts, the degree of substitution was calculated by regarding the number of sodium in the molecule as the number of carboxy groups. Specifically, the following method was used.
A carboxymethylcellulose sample was wet-decomposed with sulfuric acid-hydrogen peroxide using a microwave wet ashing device (product name: “A-300” manufactured by PROLABO), and then an atomic absorption device (product manufactured by Hitachi, Ltd., product) Name: “Z-6100 type”), the sodium content (%) was measured by atomic absorption spectrometry, and the degree of substitution was calculated by the following formula (2).
Degree of substitution (DS) = (162 × sodium content (%)) / (2300-80 × sodium content (%)) (2)

(5) Measurement of transmittance of carboxymethylcellulose aqueous solution A 1% aqueous solution of carboxymethylcellulose (100 mol% neutralized product with sodium salt) was prepared, and a spectrophotometer (trade name: “U-2000A” manufactured by Hitachi, Ltd.). ) And a quartz glass cell, and measurement was performed under the conditions of a temperature of 25 ° C., an optical path length of 1 cm, and a wavelength of 600 nm.

(6) Coloring degree Measured from the bottom of a 50 ml screw tube containing a powder sample of carboxymethyl cellulose using a color difference meter (trade name “Color and Color Difference Meter CR-200” manufactured by Konica Minolta Holdings, Inc.), b ^{* The} value (chromaticness index) was determined.

Example 1
1L kneader (Irie Shokai Co., Ltd., trade name: “PNV-1 type”), powdered cellulose (Nippon Paper Chemical Co., Ltd., trade name: “KC Flock W-400G”, crystallinity 78%, polymerization degree 193, water content 0.8%) as dry weight was charged 100.0 g (0.617 mol, converted to anhydrous glucose unit), the kneader was stirred, and 70.0 g of isopropanol was added dropwise over about 5 minutes. The inside of the kneader was depressurized (about 50 kPa), and then the operation of returning to normal pressure with nitrogen was performed three times to perform nitrogen substitution. The kneader was stirred, and 104.1 g (1.296 mol) of 49.8% aqueous sodium hydroxide solution was added dropwise thereto at 25 ° C. over 1.5 hours, followed by further stirring for 30 minutes. Next, it cooled to 5 degreeC and stirred for 15 minutes at 5 degreeC. Thereto, 116.6 g (0.617 mol) of a 50% monochloroacetic acid isopropanol solution was added dropwise at 5 ° C. over 2 hours under a nitrogen atmosphere, followed by stirring at 5 ° C. for 30 minutes. Then, it heated up at 60 degreeC and stirred for 3 hours.
The amount of organic solvent (isopropanol amount) during the reaction was 128 parts with respect to 100 parts of cellulose. The total amount of water derived from cellulose and other raw materials during the reaction was 53 parts with respect to 100 parts of cellulose.
After completion of the reaction, the reaction mixture was cooled to room temperature, and the product was taken out from the kneader and dispersed in 1000 ml of 70% aqueous methanol solution. Then, 3.7 g of acetic acid was added to neutralize excess sodium hydroxide. Next, 3000 ml of 70% aqueous methanol solution was added and stirred to elute by-product salts, unreacted substances, and the like, and then the resulting slurry was filtered. The filter cake was washed with 1000 ml of acetone and dried to obtain 132 g of carboxymethyl cellulose. The degree of substitution per unit of anhydroglucose of the obtained carboxymethylcellulose was 0.74, and the transmittance (25 ° C.) of a 1% aqueous solution was 99%.

Example 2
Carboxymethylcellulose was obtained in the same manner as in Example 1 except that isopropanol was not added during the mixing of cellulose and alkali. The amount of organic solvent (isopropanol amount) during the reaction was 58 parts with respect to 100 parts of cellulose. The total amount of water derived from cellulose and other raw materials during the reaction was 53 parts with respect to 100 parts of cellulose. The degree of substitution per unit of anhydroglucose of the obtained carboxymethylcellulose was 0.74, and the transmittance (25 ° C.) of a 1% aqueous solution was 98%.

Reference example 3
Carboxymethylcellulose was obtained in the same manner as in Example 1 except that 240.0 g of isopropanol was added during mixing of cellulose and alkali. The amount of organic solvent (isopropanol amount) during the reaction was 298 parts with respect to 100 parts of cellulose. The total amount of water derived from cellulose and other raw materials during the reaction was 53 parts with respect to 100 parts of cellulose. The degree of substitution of the obtained carboxymethyl cellulose per anhydroglucose unit was 0.81, and the transmittance (25 ° C.) of a 1% aqueous solution was 96%.

Comparative Example 1
Without performing the cooling operation after dropping the alkaline agent, a 50% monochloroacetic acid isopropanol solution was added dropwise at 25 ° C. over 2 hours, followed by stirring at 25 ° C. for 30 minutes, then raising the temperature to 60 ° C. and stirring for 3 hours. Except for this, the same operation as in Example 1 was performed to obtain carboxymethylcellulose. The degree of substitution per unit of anhydroglucose of the obtained carboxymethylcellulose was 0.86, and the transmittance (25 ° C.) of a 1% aqueous solution was 90%.

Comparative Example 2
Carboxymethylcellulose was obtained in the same manner as in Comparative Example 1 except that isopropanol was not added during mixing of cellulose and alkali. The degree of substitution of the obtained carboxymethyl cellulose per anhydroglucose unit was 0.87, and the transmittance (25 ° C.) of a 1% aqueous solution was 85%.

Generally, as the degree of substitution of the carboxyl group of carboxymethyl cellulose increases, the transmittance of the aqueous solution of carboxymethyl cellulose increases. The carboxymethyl cellulose obtained by the methods of Comparative Examples 1 and 2 had a low aqueous solution permeability, whereas the carboxymethyl cellulose obtained by the methods of Examples 1 and 2 and Reference Example 3 had a degree of substitution of Comparative Example 1. In spite of being lower than 2, it is useful as a dispersing agent or protective colloid for cosmetics and foods because of its high aqueous solution transmittance. Therefore, according to the method of the present invention, after mixing cellulose and an alkali agent, by adding monohaloacetic acid at low temperature and then reacting by heating, carboxymethylcellulose having a high aqueous solution transmittance can be efficiently obtained. And it turns out that it can manufacture easily.

  Carboxymethylcellulose obtained by the method of the present invention is useful as a dispersant or protective colloid agent for cosmetics, foods and the like.

Claims (4)

After mixing cellulose and an alkaline agent, monohaloacetic acid or a salt thereof is added at −10 to 10 ° C., and then heated to 40 to 100 ° C. to react cellulose with monohaloacetic acid or a salt thereof. It is a manufacturing method , Comprising: The manufacturing method of carboxymethylcellulose which makes a cellulose, monohaloacetic acid, or its salt react with presence of 30-200 mass parts organic solvent with respect to 100 mass parts of cellulose . After mixing the cellulose and organic solvent, mixing the alkaline agent, the production method of carboxymethyl cellulose of claim 1. The manufacturing method of the carboxymethylcellulose of Claim 1 or 2 whose water content at the time of reaction is 100 mass parts or less with respect to 100 mass parts of cellulose. The manufacturing method of the carboxymethylcellulose in any one of Claims 1-3 whose transmittance | permeability in optical path length 1cm and wavelength 600nm of the 1 mass% aqueous solution of the obtained carboxymethylcellulose is 90% or more.