JP2010106197A - Method for producing carboxymethylcellulose - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for selectively producing carboxymethylcellulose with extremely high reaction efficiency of monohaloacetic acid or its salt. <P>SOLUTION: This method for producing carboxymethylcellulose comprises reacting powdery cellulose of low crystallinity with monohaloacetic acid or its salt in the presence of a base and in the absence of an organic solvent. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a carboxymethyl cellulose.

  Carboxymethyl cellulose (hereinafter also referred to as “CMC”) is very widely used as a thickener, a dispersant, an emulsifier, a protective colloid agent, a stabilizer and the like. This CMC is industrially produced by a solvent method in which cellulose is treated with a large amount of alkaline water to be activated (arcelerized) as alkali cellulose, and then dispersed in a water-containing organic solvent and reacted with monohaloacetic acid. Yes. In this solvent method, a hydrophilic solvent such as isopropanol is used. However, the side reaction of these solvents and water with monohaloacetic acid is inevitable, and the reaction rate of monohaloacetic acid to cellulose is low. An excessive amount is required to obtain In addition, there is a problem that the load of a purification process for removing neutralized salts derived from excess alkali, hydroxymethyl acetate obtained as a side reaction product, and the like by washing or the like increases.

  In Patent Document 1, in order to increase the utilization efficiency of monohaloacetic acid, alkali cellulose is produced by the reaction of cellulose with an excess molar amount of alkali metal component with respect to glucose unit, and neutralized with an acid component containing monohaloacetic acid and organic acid. In addition, a method for producing carboxymethylcellulose or a salt thereof that is etherified while maintaining a neutral to weakly basic region is disclosed. However, the effective utilization rate of monohaloacetic acid is 58 to 65%, which is not satisfactory.

JP-A-9-176201

  An object of the present invention is to provide a method for selectively producing carboxymethyl cellulose, which has a very high reaction efficiency of monohaloacetic acid or a salt thereof.

The present inventors have found that the reaction with monohaloacetic acid or a salt thereof can proceed extremely efficiently and selectively by using low crystalline powdered cellulose as a reaction raw material.
That is, the present invention is a method for producing carboxymethyl cellulose, in which low crystalline powdery cellulose is reacted with monohaloacetic acid or a salt thereof in the presence of a base.

  According to the method of the present invention, carboxymethyl cellulose can be produced extremely efficiently, selectively and simply.

  The method for producing carboxymethylcellulose of the present invention is characterized in that low crystalline powdery cellulose is reacted with monohaloacetic acid or a salt thereof (hereinafter also referred to as “monohaloacetic acid etc.”) in the presence of a base. Hereinafter, each component used in the method of the present invention, reaction conditions, and the like will be described.

[Low crystalline powdered cellulose]
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 existing in part.
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 is the diffraction intensity of the grating plane (002 plane) (diffraction angle 2θ = 22.6 °) in X-ray diffraction, and I _18.5 is the amorphous portion (diffraction angle 2θ = 18.5 °). The diffraction intensity is shown. ]
“Low crystallinity” means a state in which the ratio of the amorphous part is large in the crystal structure of cellulose. Specifically, the cellulose I-type crystallinity according to the above formula (1) is preferably 50% or less. Including the case where the crystallinity is 0%.
Ordinary powdered cellulose has a small amount of amorphous part, and the crystallinity thereof is so-called crystalline cellulose included in the range of approximately 60 to 80% according to the above formula (1). This crystalline cellulose has a very low reactivity in general cellulose derivative synthesis, whereas the low crystalline powdery cellulose used in the present invention is excellent in chemical reactivity.

From the viewpoint of chemical reactivity, the crystallinity of the low crystalline powder cellulose used in the present invention is preferably 50% or less, more preferably 40% or less, and still more preferably from the above formula (1). 30% or less. If the crystallinity is 50% or less, the reaction with the monohaloacetic acid and the like by the base proceeds very well, so that the selectivity of the cellulose etherification reaction can be improved, and the position of the substituent introduction site General bias can be reduced. From this point of view, it is most preferable to use so-called non-crystallized cellulose that has been made completely amorphous, that is, the crystallinity according to the formula (1) is almost 0%.
The cellulose I type crystallinity defined by the formula (1) may be a negative value in calculation, but in the case of a negative value, the cellulose I type crystallinity is 0%.

The average particle size of the low crystalline powdered cellulose is preferably 300 μm or less, preferably 150 μm or less, from the viewpoint of chemical reactivity when using low crystalline cellulose as an industrial raw material, and from the viewpoint of maintaining good fluidity as a powder. Is more preferable, 100 μm or less is more preferable, and 50 μm or less is still more preferable. Further, from the viewpoint of industrial operability, the average particle size is preferably 20 μm or more, and more preferably 25 μm or more.
Moreover, in order to avoid the mixing of a trace amount of coarse particles due to aggregation or the like, it is preferable to use an unsieved product using a sieve having a size of about 25 to 100 μm as necessary for the reaction.
The degree of polymerization of the low-crystalline powdery cellulose is 100 to 2000, more preferably 100 to 1000, from the viewpoint of chemical reactivity and from the viewpoint of raw material pulp and operability in industrial implementation.

[Preparation of low crystalline powdered cellulose]
The low crystalline powdery cellulose used in the present invention can be prepared from a sheet-like or roll-like pulp having high cellulose purity obtained as a general-purpose raw material. For example, it can be prepared by the methods described in JP-A-62-236801, JP-A-2003-64184, JP-A-2004-331918, and the like.
Moreover, as a method for more efficiently obtaining low crystalline powdered cellulose, for example, obtained by roughly pulverizing sheet-like pulp, preferably 1-50 mm square, more preferably 1-30 mm square chip-like pulp, The method of preparing by processing with a ball mill after processing with an extruder is mentioned.

Here, as the extruder, a single-screw or twin-screw extruder can be used, but from the viewpoint of applying a strong compressive shearing force, it is more preferable to have a so-called kneading disk portion in any part of the screw. .
The kneading disc portion is composed of a plurality of kneading discs, which are combined while being shifted at a constant phase. For example, a combination of 3 to 20 kneading disks, preferably 6 to 16 kneading disks, which are staggered at a phase of 90 °. The kneading disk portion can be continuously processed while applying a very strong shearing force by forcibly passing chip-like pulp through the narrow gap as the screw rotates. As a shear rate in an extruder process, 600-3000 sec < ^-1 > is preferable and 6000-2000 sec < ^-1 > is more preferable.

As the ball mill, a known vibration ball mill, medium stirring mill, rolling ball mill, planetary ball mill, or the like can be used. There is no restriction | limiting in particular in the material of the ball | bowl used as a medium, For example, iron, stainless steel, an alumina, a zirconia etc. are mentioned. The outer diameter of the ball is preferably 0.1 to 100 mm from the viewpoint of efficiently reducing the crystallinity of cellulose. In addition to the ball, a medium such as a rod or tube can be used as the medium.
The treatment time of the ball mill is preferably 5 minutes to 72 hours from the viewpoint of reducing the crystallinity. Further, in the ball mill treatment, it is preferable to carry out the treatment at a temperature of 250 ° C. or lower, preferably 5 to 200 ° C. in order to minimize the denaturation and deterioration due to the generated heat. , Under an inert gas atmosphere such as nitrogen.
By using the method as described above, it is possible to control the molecular weight, and it is possible to easily prepare powdered cellulose having a high degree of polymerization and low crystallinity, which is generally difficult to obtain.

[Production of carboxymethyl cellulose]
In the method for producing carboxymethylcellulose of the present invention, the low crystalline powdery cellulose is reacted with monohaloacetic acid or a salt thereof in the presence of a base.
Examples of the monohaloacetic acid or a salt thereof used in the present invention include monochloroacetic acid, monobromoacetic acid, sodium monochloroacetate, potassium monochloroacetate and the like, and sodium monochloroacetate is particularly preferable.
The base used in the present invention is not particularly limited, and examples thereof include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, and alkaline earth metal hydroxides such as magnesium hydroxide and calcium hydroxide. And tertiary amines such as trimethylamine, triethylamine, and triethylenediamine. In these, an alkali metal hydroxide is preferable, sodium hydroxide and potassium hydroxide are more preferable, and sodium hydroxide is still more preferable.
Said monohaloacetic acid etc. and a base can be used individually or in combination of 2 or more types.
In the present invention, the reaction can be carried out in the presence of an organic solvent for the purpose of improving the dispersibility of cellulose and the miscibility with a base and monohaloacetic acid.
As a solvent to be used, non-aqueous polar solvents include secondary alcohols or tertiary alcohols such as isopropanol and tert-butanol; ether solvents such as diglyme such as 1,4-dioxane, ethylene glycol dimethyl ether and diethylene glycol dimethyl ether, and triglyme. A hydrophilic polar solvent such as dimethyl sulfoxide. On the other hand, non-aqueous low polarity or non-polar solvents such as toluene, benzene, hexane and other hydrocarbon oils can also be used.
Said solvent can be used individually or in combination of 2 or more types.

(Addition of base, monohaloacetic acid, etc.)
There is no particular limitation on the method of adding the base. For example, (i) a method in which low crystalline powdery cellulose is mixed in advance with monohaloacetic acid and then dropped as an aqueous base solution, or (ii) a low crystalline powdery cellulose in advance. Examples thereof include a method of adding a monohaloacetic acid after mixing the base. Among these, the method (i) is more preferable from the viewpoint of controlling the reaction temperature and preventing lumping.
There is no particular restriction on the nature of the base to be added, and therefore the base can be mixed and added in an anhydrous state or as an aqueous solution. However, when adding by the method (i), the base is added as an aqueous solution. The concentration is not particularly limited, but a range of 20 to 50% by mass is preferable.
The addition method of monohaloacetic acid and the like is not particularly limited. For example, (iii) a method in which monohaloacetic acid or the like is gradually added dropwise after adding a base to powdered cellulose, or (iv) monohaloacetic acid or the like is added to powdered cellulose in a lump. Then, a method of adding a base and reacting it can be mentioned.

(Amount of base and monohaloacetic acid used)
In the present invention, the reaction efficiency between powdered cellulose and monohaloacetic acid or a salt thereof is extremely high, and the reaction proceeds almost quantitatively. Therefore, it is sufficient to use the base in an amount of 1 to 1.05 moles, especially with respect to the monohaloacetate. However, when monohaloacetic acid is used, an amount capable of completely neutralizing the carboxyl group is required.
In addition, the amount of monohaloacetic acid or its salt used is such that the reaction proceeds very quantitatively, so that the amount corresponding to the desired degree of substitution (introduced molar amount per glucose unit in the cellulose molecule) is used. The degree can be adjusted as appropriate. The carboxymethyl group in the obtained carboxymethyl cellulose may be bonded to the hydroxyl group at any position in the glucose unit in the cellulose molecule.

(Reaction conditions)
The reaction temperature in the present invention is preferably a temperature equal to or lower than the boiling point of monohaloacetic acid, specifically 30 to 100 ° C, more preferably 40 to 80 ° C.
The reaction is preferably carried out under normal pressure, and is preferably carried out under an inert gas atmosphere such as nitrogen as necessary from the viewpoint of avoiding coloring during the reaction.
In the present invention, it is preferable to react low crystalline powdered cellulose, base, monohaloacetic acid and the like in a fluid powder state. More specifically, powdered cellulose and base, or powdered cellulose and monohaloacetic acid, etc. Is preferably mixed in advance with a mixer such as a mixer or a shaker, and then reacted with monohaloacetic acid or the like or a base. If the reaction is performed in the powder state, the burden of the organic solvent removal step after the reaction is small or unnecessary, which is industrially simple and advantageous.

In the reaction of low crystalline powdered cellulose with monohaloacetic acid, etc., it depends on the moisture present in the reaction vessel (also referred to in the reaction system) at the time of reaction, such as powdered cellulose used in the reaction and moisture derived from raw materials such as aqueous base , Raw materials and products may agglomerate. Therefore, the amount of water present in the reaction system is preferably 100% by mass or less, more preferably 80% by mass or less, still more preferably 50% by mass or less, and particularly preferably 5 to 50% by mass with respect to the powdered cellulose. . If the amount of water present in the reaction system is within the above range, the raw material powdered cellulose and the product carboxymethylcellulose are not excessively aggregated and can be reacted in a fluid powder state.
In order to keep the water content with respect to the powdered cellulose within the above range, it is also preferable to dehydrate under a reduced pressure condition or the like together with the dropwise addition and reaction of the aqueous base, and the pressure at that time is preferably 13.3 to 101 kPa, 6.6 to 13.3 kPa is more preferable.
The amount of the organic solvent used is 100% by mass or less, more preferably 80% by mass or less, particularly preferably 80% by mass or less, based on the powdered cellulose, from the viewpoint of reacting in a fluid powder state. The content is preferably 50% by mass or less.

(Reactor)
Although there is no restriction | limiting in particular as a reaction apparatus used by this invention, In order to react in the said powder state with the fluidity | liquidity, what can mix a low crystalline powder cellulose, a base, a monohalo acetic acid etc. as uniformly as possible is preferable. For example, a mixer such as a so-called kneader used for kneading resins or the like as disclosed in paragraph [0016] of JP-A-2002-114801 is preferable.
Here, the mixer such as a kneader is not particularly limited as long as it can sufficiently stir. For example, the chemical engineering association edition “Chemical Engineering Handbook” revised 5th edition (published by Maruzen Co., Ltd.), pages 917 to 919 As described above, examples of the single-axis kneader include a ribbon mixer, a kneader, a botter, and a screw-type kneader, and examples of the biaxial kneader include a double-arm kneader.
It is more preferable that these mixers have a portion where the aqueous base solution can be dropped and dehydrated.

In the present invention, since the reaction selectivity with respect to cellulose such as monohaloacetic acid is extremely high, by-products derived from monohaloacetic acid and the like are extremely small, post-treatment such as purification after completion of the reaction is easy. That is, in the present invention, after the reaction is completed, in order to remove a trace amount of unreacted monohaloacetic acid and the like and by-product neutralized salt, if necessary, after washing with water-containing isopropanol, water-containing acetone solvent, etc., drying is performed. The target carboxymethyl cellulose can be obtained by a simple purification treatment such as.
Further, after completion of the reaction, without performing a purification treatment such as neutralization salt removal, a catalytic amount of a base or the like is added as necessary, and then a further derivatization reaction is performed, so that various cellulose ether derivatives are obtained from powdered cellulose. It can also be synthesized in one pot.

  The crystallinity, degree of polymerization, average particle size, and water content of the low crystalline cellulose obtained in the production example were measured by the following methods.

(1) Calculation of crystallinity The cellulose I type crystallinity is measured by measuring the X-ray diffraction intensity of a sample using the “Rigaku RINT 2500VC X-RAY diffractometer” manufactured by Rigaku Corporation under the following conditions. Calculated based on (1).
The measurement conditions were X-ray source: Cu / Kα-radiation, tube voltage: 40 kv, tube current: 120 mA, measurement range: 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 degree of polymerization The degree of polymerization of cellulose was measured by the copper ammonia method described in ISO-4312 method.
(3) Measurement of average particle diameter The average particle diameter was measured using a laser diffraction / scattering particle size distribution measuring apparatus “LA-920” (manufactured by Horiba, Ltd.). The measurement conditions were ultrasonic treatment for 1 minute before particle size measurement, water was used as a dispersion medium during measurement, and the volume-based median diameter was measured at a temperature of 25 ° C. The refractive index used is 1.2.
(4) Measurement of moisture content The moisture content was measured at 150 ° C using an infrared moisture meter ("FD-610", manufactured by Kett Scientific Laboratory).

Production Example 1 (Production of Amorphized Powdered Cellulose)
First, a commercially available wood pulp sheet (Boregard pulp sheet, crystallinity 74%) was applied to a shredder (manufactured by Meiko Shokai Co., Ltd., “MSX2000-IVP440F”) to form a 1 cm square chip. Next, the obtained chip-like pulp was charged at 2 kg / hr into a twin-screw extruder ("EA-20" manufactured by Suehiro EPM Co., Ltd.) equipped with a kneading disk at the center of the screw, and a shear rate of 660 sec. ^-1 and powdered by one pass treatment with cooling water flowing from outside under the condition of screw rotation speed of 300 rpm. Next, 100 g of the powdered cellulose was put into a batch-type medium stirring ball mill (“Attritor” manufactured by Mitsui Mining Co., Ltd .: a container volume of 800 mL, 1400 g of 6 mmφ steel balls filled, a stirring blade diameter of 65 mm). did. While passing cooling water through the container jacket, pulverization was performed at a stirring rotational speed of 600 rpm for 3 hours to obtain powdered cellulose (crystallinity 0%, polymerization 600, average particle size 40 μm). For the reaction of the powdered cellulose, a sieved product having a sieve with an opening of 32 μm was used.

Example 1
A non-crystalline powdery cellulose obtained in Production Example 1 (crystallinity 0%, polymerization degree 600, average particle size 40 μm, water content 5 mass%) in a 1 L kneader (manufactured by Irie Shokai Co., Ltd., PNV-1 type) 80.0 g (0.47 mol in terms of glucose unit) and 58.0 g (0.50 mol) of sodium chloroacetate (reagent manufactured by Wako Pure Chemical Industries, Ltd.) were added, and the mixture was stirred under a nitrogen atmosphere for 6 hours. Next, the temperature was raised to 50 ° C. in a nitrogen atmosphere, and 42.0 g of a 48 mass% sodium hydroxide aqueous solution (NaOH amount 0.50 mol) was added dropwise over 2 hours, followed by stirring at 50 ° C. for 6 hours. During that time, the cellulose and the product were kept in a fluid powder state without agglomeration at all (total amount of water derived from cellulose and other raw materials: 13% by mass with respect to cellulose).
After completion of the reaction, the mixture is cooled to room temperature, the product is taken out from the kneader, and by-product salts and unreacted substances are removed by washing with 3000 ml of water-containing isopropanol (water content: 15% by mass) and 1000 ml of isopropanol, and dried to give 114 g. Of a white solid was obtained.
This white solid was identified as carboxymethyl cellulose (Na salt) using an infrared spectrophotometer (FT-IR measuring device FT-710 manufactured by Horiba, Ltd.). The infrared absorption spectrum is shown in FIG.
The degree of substitution of the carboxymethyl group per glucose unit determined from the amount of substituent introduced was 1.0. Further, the reaction selectivity to cellulose on the basis of the raw material sodium chloroacetate was 95%, and the reaction proceeded almost quantitatively.

Example 2
A non-crystalline cellulose obtained in Production Example 1 (crystallinity 0%, polymerization degree 600, average particle size 40 μm, water content 5 mass%) 70 in a 1 L kneader (manufactured by Irie Shokai Co., Ltd., PNV-1 type) 0.0 g (0.41 mol in terms of glucose unit) and 70.0 g (0.60 mol) of sodium chloroacetate (reagent manufactured by Wako Pure Chemical Industries, Ltd.) were added, and the mixture was stirred for 6 hours in a nitrogen atmosphere. Next, after raising the temperature to 50 ° C. in a nitrogen atmosphere, 52.0 g of a 48 mass% sodium hydroxide aqueous solution (NaOH amount 0.62 mol) was added dropwise over 5 hours, and the mixture was stirred at 50 ° C. for 12 hours. In the meantime, the cellulose and the product kept a fluid powder state without agglomeration at all (total amount of water derived from cellulose and other raw materials: 15% by mass with respect to cellulose).
After completion of the reaction, it was cooled to room temperature, the product was removed from the kneader, and by-product salts and unreacted substances were washed away with 3000 ml of hydrous isopropanol (water content 15% by mass) and 1000 ml of isopropanol, and dried, 115 g of carboxymethylcellulose (Na salt type) was obtained as a white solid.
The degree of substitution of the carboxymethyl group per glucose unit determined from the amount of substituent introduced was 1.4. The reaction selectivity to cellulose based on the raw material sodium chloroacetate was 97%, and the reaction proceeded almost quantitatively.

Comparative Example 1
As powdered cellulose, the same procedure as in Example 1 was used except that commercially available powdered cellulose (cellulose powder manufactured by Nippon Paper Chemical Co., Ltd .; KC floc, crystallinity 74%, average particle size 45 μm, water content 5 mass%) was used. When the reaction was carried out, partial aggregation was observed with the progress of the reaction, and the reaction mixture was very heterogeneous and sufficient mixing was not possible, but the operation was continued as it was and the byproduct salt was the same as in Example 1. Then, unreacted substances and the like were removed and dried.
The degree of substitution of the carboxymethyl group per glucose unit determined from the amount of substituent introduced was 0.93, and the reaction selectivity to cellulose on the basis of raw material sodium chloroacetate was 89%.

According to the method of the present invention, carboxymethylcellulose can be produced efficiently, selectively and simply. For this reason, the method of the present invention is extremely advantageous industrially.
The obtained carboxymethyl cellulose can be widely used as a blending component such as a thickener, a dispersant, an emulsifier, a protective colloid agent, a stabilizer and the like, and as a starting material for producing other cellulose ether derivatives.

2 is an infrared absorption spectrum of carboxymethylcellulose (Na salt) obtained in Example 1.

Claims (5)

  A process for producing carboxymethylcellulose, comprising reacting low-crystalline powdery cellulose with monohaloacetic acid or a salt thereof in the presence of a base.   The method for producing carboxymethyl cellulose according to claim 1, wherein the crystallinity of the low-crystalline powdery cellulose is 50% or less.   The method for producing carboxymethyl cellulose according to claim 1 or 2, wherein the base is an alkali metal hydroxide or an alkaline earth metal hydroxide.   The manufacturing method of the carboxymethylcellulose in any one of Claims 1-3 whose water content in the reaction container at the time of reaction is 100 mass% or less with respect to low crystalline powdered cellulose.   The manufacturing method of the carboxymethylcellulose in any one of Claims 1-4 whose average particle diameters of a low crystalline powder cellulose are 20-300 micrometers.

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