JP3516358B2 - Method for granulating and drying alkali salts of carboxymethyl cellulose ether - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for granulating and drying a carboxymethyl cellulose ether alkali salt (hereinafter referred to as "CMC") containing a solvent and water, which has improved water solubility and solubility. It is a method capable of producing excellent CMC.

[0002]

2. Description of the Related Art Conventionally, CMC is made from pulp and the like,
After the alkaline reaction, an etherification reaction is carried out, followed by neutralization with acetic acid or the like, and draining filtration to prepare a crude CMC. Then, it is made into an aqueous methanol solution for desalination purification,
Next, the filtered CMC is dried by hot air, and finally crushed to produce. In the hot air drying, a usual dryer is used.

[0003]

However, the drying method using the dryer has the following drawbacks.

[0004] CMC adheres to the inside of the drier and coloring occurs due to heating of the drier (so-called spot), which is mixed in the product and causes deterioration of quality. Since the obtained CMC particles have a non-uniform particle size and are often in the form of fine powder (particle size of 20 μm or less), there are many powder particles,
There is a problem in workability. When CMC is used, dust is generated, which has a bad irritating effect on the human body. Since the particle size is non-uniform and there are many fine powders, when dissolved in water, a continuous powder is likely to be formed, and since it becomes a clump, the solubility deteriorates, and it takes a long time for dissolution.

Further, spray drying with an aqueous solution (air hot air) is usually a common method, but spray drying with a solvent-containing system poses a risk of explosion and poses a problem in industrialization.

The present invention has been made in view of the above circumstances, and has a uniform dry powder particle size, suppresses the generation of fine powder, and can be applied to a system containing a solvent.
The purpose is to provide a granulation and drying method of C.

[0007]

In order to achieve the above object, the method of granulating and drying CMC of the present invention is a method of spray drying a solvent-water containing slurry of CMC to granulate. The spray-drying is performed by flowing the slurry on a rotating disk to atomize it under an atmosphere of at least one of inert gas and air, or by spraying from a nozzle to atomize.

[0008]

That is, the present invention is a solvent-water containing CMC.
The slurry is atomized by flowing down on a rotating disk under an atmosphere of at least one of an inert gas and air. Alternatively, it is a granulation and drying method of CMC in which spraying is performed from a nozzle and atomized to thereby spray-dry and granulate. As a result, high quality CMC powder can be obtained without mixing spots or the like due to coloring by heating and drying in the conventional method. Moreover, the particle size is uniform, and the content ratio of fine powder having a particle size of 20 μm or less is much smaller than in the conventional case. Therefore, when CMC is dissolved in water, the phenomenon of formation of lumps, which has been conventionally observed, does not occur, and it quickly dissolves in water, so that the dissolution time during use is greatly shortened. Furthermore, there is little dusting and the handling property is good. Further, when CMC powder is used, the generation of dust is small, and there is no problem such as a bad influence of irritation on the human body.
Further, even in a system containing a solvent, it can be dried without danger of explosion.

Next, the present invention will be described in detail.

In the method for granulating and drying CMC according to the present invention, the target CMC is a usual one and is not particularly limited. For example, the degree of ether substitution is 0.5 to
In 2.8, the types of alkali salt are sodium salt,
Examples thereof include potassium salt, calcium salt, ammonium salt and the like. Usually it is the sodium salt. And CMC is
Any of crude CMC and purified CMC obtained by adding a step of removing the by-product salt using this crude CMC may be used.

Next, the content of CMC in the CMC slurry is preferably set in the range of 5 to 70% by weight (hereinafter abbreviated as "%"). That is, when the content of CMC exceeds 70%, the CMC solidifies into a dumpling-like shape and is not loosened, making it difficult to transport the slurry. For this reason, it becomes very difficult to perform spray drying. A mixture of solvent and water is used as the solvent of the slurry.
At this time, the mixing ratio of both is water / solvent = 3 by weight ratio.
It is preferable to set the ratio to / 97 to 40/60,
Water / solvent = 5/95 to 20/80 is particularly preferable. That is, when the water content is less than 3% (solvent exceeds 97%) in the mixing ratio of both, a large amount of fine powder is likely to be generated in the product obtained by drying. If the water content exceeds 40% (solvent content is less than 60%), the latent heat of vaporization of water is high, a large amount of heat is required, and the drying cost becomes high, which is not preferable. Further, the CMC is dissolved and the system becomes a paste, which tends to deteriorate fluidity.

The viscosity of the CMC slurry is 10 mP.
There is no particular problem as long as it is at least a · s, the slurry can be transported, and spray drying is possible.

As the above solvent, it is preferable to use a lower alcohol having 1 to 4 carbon atoms. For example, methanol, ethanol, isopropyl alcohol, etc. may be mentioned.

Next, the method for granulating and drying CMC of the present invention will be described.

The granulation and drying of the CMC of the present invention is performed as follows, for example. That is, as shown in FIG. 1, the CMC slurry is charged into the raw material tank 1, the CMC slurry is supplied into the chamber 3 from the upper part of the chamber 3 through the pipe by the supply pump 2, and the CMC slurry flows down onto the rotating disk 5. Let At this time, the rotating disk 5 connected to the motor 4 rotates, and the CMC slurry supplied into the chamber 3 becomes atomized. On the other hand, a gas supply port 7 is provided in the upper part of the side wall of the chamber 3, and the gas is supplied into the chamber 3 by the blower 6. Then, the atomized CMC slurry comes into contact with the supplied gas and is dried to become a powder. The powdered CMC falls by its own weight and is collected by the collector 8 provided at the center of the lower end.
The supplied gas and the gas of the vaporized solvent are sucked from the exhaust port 9 and exhausted to the outside of the system by the exhaust fan 12. 1
0 was partly stirred in gas and solvent gas, and the collector 8
In the cyclone type collector for collecting the CMC that has not been collected, the collected CMC is collected in the collecting unit 11 provided at the center of the lower end of the cyclone type collector 10.

The supply temperature of the CMC slurry supplied into the chamber 3 is set within the range of 10 ° C. to the boiling point of the contained solvent. Particularly, from the viewpoint of drying efficiency, it is preferable to set a higher supply temperature. Further, the supply amount of CMC slurry is appropriately set according to the scale of the entire apparatus and the CMC concentration.

The gas supplied into the chamber 3 is
Inert gas and air are used, and these are used alone or as a mixed gas of two in combination. The inert gas is not particularly limited, and a conventionally known gas can be used. For example, nitrogen gas, carbon dioxide gas, or a mixed gas thereof may be used. Then, these inert gases are repeatedly used. Further, in the mixed gas in which the inert gas and air are mixed, the mixing ratio of the air is appropriately set, but it is necessary to mix air into the inert gas so that the oxygen concentration is below the explosion limit. . Further, when air alone is supplied as the gas to be supplied, the CMC of the CMC slurry is prevented so that an explosion does not occur.
A CMC slurry with a high concentration and a low solvent content must be used. Specifically, when using a CMC slurry in which the CMC concentration (CMC content) is set to 60% or more, it is possible to perform granulation drying by supplying only air alone. Among the gases supplied into these chambers 3, the inert gas alone is particularly preferable.

The gas supply temperature is preferably set so that the temperature of the gas in the chamber 3 is in the range of 80 to 120 ° C., and a higher temperature is preferable within this range. Then, when the gas is supplied into the chamber 3 so as to be in the above temperature range, for example, the gas is supplied by the blower 6 and simultaneously heated. Further, the gas supply amount is appropriately set according to the scale of the entire apparatus.

In the drying step, the pressure inside the chamber 3 may be either reduced pressure or normal pressure.
From the viewpoint of easy operation of the slurry and high granulation property, it is preferable to set the pressure within the range of from a weak pressure reduction of 660 to 760 mmHg to a normal pressure. Extremely reduced pressure is not preferable because the solvent contained in the slurry is rapidly gasified to cause an explosion phenomenon and fine powder.

The rotating disk 5 has a disk diameter of 5
The rotation speed of the rotary disk 5 is preferably set to 2000 to 8000 rpm. That is, if the number of rotations is too high, the particle size becomes smaller and the particles become finer, so extremely high rotations are not preferable.

FIG. 2 shows another example of the apparatus used in the granulating and drying method of CMC of the present invention. That is,
In this device, instead of atomizing the slurry using the rotary disk 5, a nozzle 13 for spraying is attached to the tip of the supply pipe,
The CMC slurry is atomized from this nozzle 13 and supplied into the chamber 3. The other configurations are similar to those of the apparatus of FIG. 1, and the same reference numerals are given to the same portions.

Although the gas is supplied from the inert gas supply port 7 provided in the upper portion of the side wall of the chamber 3 in both FIGS. 1 and 2, it is not limited to this position, and the chamber 3 is not limited to this position. May be supplied from the lower part, or both from the upper part and the lower part.

Further, in atomizing the CMC slurry,
The rotating disk 5 or nozzle 13 is used, but CMC
Considering that the viscosity of the slurry is large, the rotating disk 5
It is more preferable that the slurry is made to flow down and atomize on the rotating disk 5 by using.

The CMC powder obtained by spray-drying as described above is such that 80% or more of the powder is in the range of 70 to 200 μm in particle size, and the content of fine powder having a particle size of 20 μm or less is 2% of the whole. It becomes 0.0% or less. The particle size is measured with a Coulter counter, and the entire particle size distribution can be confirmed. The result of this measurement is shown as a chart as shown in FIG. From FIG. 3, particle size 2
The content ratio of fine powder of 0 μm or less is extremely small,
0% or more is the particle size distribution in the range of 70 to 200 μm (hatched portion). The volatile content of the obtained CMC powder is 10% or less.

[0025]

As described above, according to the method for granulating and drying CMC of the present invention, the solvent-water containing CMC slurry is treated under the atmosphere of at least one of inert gas and air.
It is made to flow on a rotating disk and atomized. Alternatively, it is a method of spray-drying by atomizing by spraying from a nozzle and granulating. Therefore, the obtained CMC powder has a high quality, a uniform particle size, and the content ratio of the fine powder having a particle size of 20 μm or less is much smaller than the conventional one. Therefore, the generation of dust during use of the CMC powder is small, and the handling property is improved. Also, it is easy to dissolve in water,
So-called powdering does not occur and a uniform water-based material can be obtained in a short time, and the dissolution work time can be shortened. Furthermore, the granulating and drying method of the present invention does not pose a risk of explosion even when drying the CMC slurry containing the solvent, and the industrialization of granulating and drying the solvent-containing CMC slurry is realized.

Next, examples will be described together with comparative examples.

Prior to drying the CMC slurry, crude CMC, purified CMC, and high-grade purified CMC, which are the raw materials, were manufactured.

[Production A of CMC] Raw material pulp (produced by Kojin Co., Ltd., sulfate method pulp) was pulverized by a pulverizer (screen diameter 0.3 mm), finely pulverized pulp 30% with a water content of 6%
g, 650 kg of isopropyl alcohol and 60 kg of water
The mixture was added to a 1 m ³ reaction kettle containing the mixed solution and stirred. To this, 33.2 kg of 48% caustic soda was added at 20 to 30 ° C. over 10 minutes, and the mixture was stirred at about 30 ° C. for 60 minutes to carry out an alkali cellulose reaction.

Next, 1 kg of 15 kg of chloroacetic acid was added to this.
After adding for 0 minutes, the reaction temperature was changed from 30 ° C to 70 ° C.
The temperature was raised over a period of minutes. Then, the mixture was stirred at 70 ° C. for 90 minutes to carry out an etherification reaction. Then, after cooling to 40 ° C. for 5 minutes, 4.6 kg of acetic acid was added to neutralize caustic soda. By such an operation, the degree of etherification (DS)
A CMC of 0.75 was obtained.

After the above neutralization operation, the solution was removed by filtration to obtain a crude CMC having a concentration of 70% and a salt amount of 11%.
(Crude CMC) was obtained. Subsequently, the above filtered crude CMC was added to 700 kg of a 80% methanol water-containing solution, stirred, desalted and washed, and then the solution was removed by filtration to obtain a purified CMC containing a salt amount of 2% (purified CMC). . Furthermore, the filtered purified CMC was added to 700 kg of a 90% methanol water-containing solution and stirred. After desalting and washing, the solution was removed by filtration to obtain 42 kg of high-grade purified CMC (high-grade purified CMC) containing a salt amount of 0.1%.

[Production of CMC B] Degree of Etherification (DS)
CMC of 1.50 was synthesized and used. Other than that, the crude CMC is manufactured under the same conditions as in the above-mentioned CMC manufacturing A.
', Purified CMC' and high-grade purified CMC 'were obtained.

[Production of CMC C] Degree of Etherification (DS)
2.30 of CMC was synthesized and used. Other than that, the crude CMC is manufactured under the same conditions as in the above-mentioned CMC manufacturing A.
", Purified CMC" and high-grade purified CMC "were obtained.

The etherification degree was determined as follows. That is, about 1.0 g of a sample (CMC) vacuum dried at 75 ° C. for 3 hours was precisely weighed and ashed in a crucible. Then, after cooling this, the ash was eluted in warm water, and 50-80 ml of N / 10-sulfuric acid was added to acidify the mixture and the mixture was boiled and cooled. Then, the excess acid was back-titrated with N / 10-sodium hydroxide, and the degree of etherification was determined from the amount of sulfuric acid consumed for alkali neutralization in the ash.

[0034]

Examples 1 to 10 Production of CMC Using crude CMC, purified CMC, ', "and high-grade purified CMC synthesized by A to C, alcohols and water shown in Table 1 below are used in the proportions shown in the same table. CM to mix
A C slurry was prepared. Using the CMC slurry prepared in this manner, it was charged into the dryer shown in FIG. 1 (the charging temperature of the CMC slurry was 30 ° C.), an inert gas was supplied, and spray drying was performed according to the above-described drying method. On this occasion,
By supplying hot air from an inert gas into the chamber 3,
The CMC slurry atomized by generating a cyclone-like hot air flow was dried in the chamber 3. And dried CM
C was collected by the collector 8 in the lower part of the chamber 3.
The diameter of the rotating disk 5 shown in FIG. 1 was 8 cm, and the inside of the chamber 3 was 740 mmHg in a weakly depressurized state. In addition,
The conditions in the above drying method are shown in Table 2 below.

[0035]

Examples 11-14 Preparation of CMC Using the crude CMC ', ", purified CMC", and high-grade purified CMC' synthesized by A to C, alcohols and water shown in Table 1 below are shown in the same table. Mix so that the ratio becomes C
An MC slurry was prepared. Using the CMC slurry prepared in this way, the CMC slurry is charged into the dryer shown in FIG. 2 (the CMC slurry charging temperature is 30 ° C.), an inert gas is supplied, and the spraying nozzle 13 is used in accordance with the drying method. The CMC slurry was atomized, supplied into the chamber 3, and spray-dried. At this time, hot air of an inert gas was supplied into the chamber 3 to generate a cyclone-like hot air flow, and the atomized CMC slurry was dried in the chamber 3. Then, the dried CMC was collected by the collector 8 in the lower part of the chamber 3. The inside of the chamber 3 was 680 mmHg in a weakly depressurized state. The conditions in the above drying method are shown in Table 2 below.

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

Comparative Examples 1 to 3 Crude CMC, purified CMC ', and high-grade purified CMC "synthesized by the above-mentioned CMC production A to C were used (see CMs shown in Table 3 below).
C), this CMC is directly heated to a temperature of 10 with a shelf type heat dryer.
In a 0 ° C atmosphere, static drying was performed for 120 minutes. When water was dried, some CMC melted and solidified into lumps,
After drying, hammer type crusher (screen diameter 0.5m
m) and then crushed and crushed. In this way, a CMC product was obtained by a method that is usually used.

[0039]

[Table 3]

The properties of the CMC thus obtained were analyzed. The particle size distribution of CMC is measured with a Coulter counter (manufactured by Coulter Counter Co.) and is 80% of the whole.
The particle size range in which the above powder is distributed (Example product) or the particle size range in which 50% or more of the powder is distributed (Comparative example product) and the content of fine powder having a particle size of 20 μm or less are shown in Tables 4 and 5 below. Shown in. Further, the dusting property and the solubility of the CMC powder were visually evaluated according to the following. Also, C
The dissolution rate of MC powder was measured. The results are also shown in Table 6 below.

[Dust Generation Property of CMC Powder] 100 CMC samples were used.
A 1/2 volume was put into a ml screw tube, and this was stirred up and down. As a result, those in which there was no dust of fine powder were indicated by ◯, and those in which dust of fine powder was large were indicated by X.

[Solubility and dissolution rate of CMC powder] 10
Put 800 ml of water in a 00 ml beaker and put CM in this
8 g of C sample (1% concentration) was added. As a result, ◯ indicates that the particles were immediately dispersed and could be dissolved in water quickly, and x indicates that a powdered lump was formed immediately and that it took a long time to dissolve in water. Further, the time until the CMC sample was completely dissolved was measured by lightly stirring.

[0043]

[Table 4]

[0044]

[Table 5]

[0045]

[Table 6]

From the results of Tables 4 to 6 above, the comparative example is CM
In the distribution area of C, 50% or more of the total particle size is 32 to
Within the range of 85 μm, the content ratio of fine powder having a particle size of 20 μm or less is 10% or more of the whole. On the contrary,
Example products are 80% of the total in the distribution area of CMC.
The above is in the range of particle size 70 to 200 μm, and the content ratio of fine powder having a particle size of 20 μm or less is 1.7% or less of the whole. From this, it can be seen that the products of Examples had few small particle diameters, and moreover, uniform CMC powders with little variation in particle diameter were obtained. Furthermore, in the example products, good evaluation results were obtained in terms of both dust generation and solubility. Further, the dissolution rate in water was also much higher than that of the comparative example product.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an apparatus used in a method for granulating and drying CMC of the present invention.

FIG. 2 is a cross-sectional view showing another example of the apparatus used in the CMC granulation drying method of the present invention.

FIG. 3 CM measured by Coulter Counter
It is a chart figure which shows the particle size distribution state of C powder.

[Explanation of symbols]

3 chambers 5 rotating disks 8 collector 13 nozzles

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-54-32176 (JP, A) JP-A-55-5798 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08B 11/12 B01J 2/04 F26B 3/12 F26B 17/10 JISC file (JOIS)

Claims (2)

(57) [Claims] 1. A method of granulating by spray-drying a solvent-water containing slurry of carboxymethyl cellulose ether alkali salt, wherein the spray-drying is carried out under an atmosphere of at least one of an inert gas and air. A method for granulating and drying carboxymethyl cellulose ether alkali salt, characterized in that the carboxymethyl cellulose ether alkali salt is caused to flow on a rotating disk for atomization or is sprayed from a nozzle for atomization. 2. The content of the carboxymethyl cellulose ether alkali salt in the solvent-water containing slurry of the carboxymethyl cellulose ether alkali salt is 5 to 7.
The method for granulating and drying carboxymethyl cellulose ether alkali salt according to claim 1, which is 0% by weight.