JP5150660B2 - Method for drying water-soluble cellulose ether - Google Patents

Description

  The present invention relates to a method for drying water-soluble cellulose ethers used as pharmaceuticals, food binders, disintegrants, thickeners for various solvents, water retention agents for building materials, binders in extrusion molding processes, suspension stabilizers, and the like. Is.

  In order to make cellulose water-soluble, there is water-soluble cellulose ether as an etherification of the hydroxyl group of cellulose. Water-soluble cellulose ethers are used in a large amount in many fields such as thickeners for various solvents, water retention agents for building materials such as cement and plaster, ceramics, and binders in cement-based extrusion molding processes.

  Water-soluble cellulose ether is generally produced by adsorbing caustic soda to cellulose to make alkali cellulose, reacting with an alkylating agent or hydroxylating agent, and washing, dehydrating, drying, and pulverizing steps.

  In the drying process, an air dryer and a cylindrical rotary dryer with a steam heating tube are generally used (Patent Documents 1 to 3). However, since the air dryer has a low thermal efficiency of 50 to 60%, the drying cost is high and it is difficult to manage the water content of the water-soluble cellulose ether. The cylindrical rotary dryer with a steam heating tube requires a wide installation area, has poor thermal efficiency, and water-soluble cellulose ether adheres to the inside of the machine, and foreign matter due to the generation of agglomerated thermal change is mixed therein. In addition, the temperature of the processed product in the machine cannot be measured at all times because a thermometer with a transmitter cannot be installed, which causes insufficient management of the water content of the water-soluble cellulose ether, resulting in a decrease in crystal quality due to overdrying. Or undried product may be discharged.

JP-A-8-73501 JP-A-8-259601 Japanese Patent Laid-Open No. 2001-233961

  The present invention was made to solve the above-mentioned problems, does not require a large installation area for a dryer, has low thermal cost because it has good thermal efficiency, and can manage the water content of the water-soluble cellulose ether, It aims at providing the drying method of water-soluble cellulose ether which can prevent a quality fall.

  In the present invention, water-soluble cellulose ether having a moisture content of 35 to 50% by mass is continuously charged into a container of a grooved agitation dryer by an air-flow dryer, and steam at atmospheric pressure or more flows into the container. The water-soluble cellulose ether drying method is characterized in that the rotor blade is rotated while being heated to 105 to 200 ° C. and continuously dried, and the water-soluble cellulose ether to be charged is 5 to 40 ° C. A method for drying a water-soluble cellulose ether is provided.

  When the water-soluble cellulose ether is dried by the method of the present invention, a large installation area for a dryer is not necessary, and the cost is low because the thermal efficiency is good. In addition, the water content of the water-soluble cellulose ether can be controlled, and foreign matters due to the generation of the aggregated heat-transformed material are not mixed, and quality deterioration can be prevented.

It is a side view which shows the groove type stirring dryer for enforcing the drying method of water-soluble cellulose ether to which this invention is applied. It is sectional drawing of the AA line of FIG.

Hereinafter, embodiments of the present invention will be described in detail.
As a ditch-type stirring dryer for carrying out the method for drying water-soluble cellulose ether of the present invention, a dryer having a small installation area, good thermal efficiency, and no need for heat transfer by hot air is shown in FIGS. An example of the groove type agitation dryer 10 is given. 1 and 2 show a side view and a cross-sectional view of the grooved stirring dryer 10.
The grooved agitation dryer 10 is a dryer that rotates and stirs the rotating blades 21 to 24 in the container 15 and stirs because the volume filling rate of the product to be dried is almost 100%. Time is obtained and a homogeneous stirring state per unit volume in the machine is maintained. The volume filling rate is the ratio of the in-machine filling volume of the processed product to the effective volume of the dryer.

The grooved agitation dryer 10 shown in FIGS. 1 and 2 will be described in more detail.
A drying container 15 is formed from the upper cover 11 and the lower jacket 12. The upper cover 11 is provided with a raw material supply port 1, a carrier gas supply port 2 and a carrier gas exhaust port 3, and the lower jacket 12 has a carrier. A gas supply port 4 and a product discharge port 5 are provided. A thermometer 20 with a transmitter is fixed to the product outlet 5. An outer jacket 13 is fixed to the lower jacket 12 to form a space 14 through which a heat medium for adjusting the temperature in the container flows. The outer jacket 13 has a heat medium supply port 6 and a heat medium discharge port 7. Is provided.

  Two hollow rotary shafts 16 to 17 pass through the outer jacket 13, and a steam supply port 8 for flowing steam for heating in the hollow rotary shafts 16 to 17 is provided on the raw material supply port 1 side. A steam discharge port 9 is provided on the product discharge port 5 side. The hollow rotary shafts 16 and 17 are fitted with gears 18 and mesh with each other. The hollow rotary shaft 16 is connected to a motor 25 via a belt. When the motor 25 is driven, the hollow rotary shafts 16 to 17 are connected to each other. They are designed to rotate in opposite directions.

  Inside the container 15, saddle-shaped hollow rotary blades 21 to 24 are fixed to the hollow rotary shafts 16 to 17, respectively, and the internal space of the hollow rotary shafts 16 to 17 and the internal space of the hollow rotary blades 21 to 24 are Between them, pipes 26 to 27 are respectively provided so as to allow steam to flow therethrough.

The method for drying the water-soluble cellulose ether of the present invention is carried out by taking the case of using the grooved stirring dryer 10 of FIG. 1 as an example.
First, the motor 25 is driven while the heating steam is sent to the hollow rotary shafts 16 to 17 to rotate the hollow rotary blades 21 to 24. Then, the hollow rotary blades 21 to 24 are heated as the steam flows from the hollow rotary shafts 16 to 17.
When water-soluble cellulose ether having a water content of 35 to 90% by mass is continuously charged into the container 15 in this state from the raw material supply port 1, the water-soluble cellulose ether repeatedly contacts the heated hollow rotor blades 21 to 24. However, it moves through the defect | deletion part 28 like a chain line arrow, and is dried continuously. After the drying process, the product is continuously discharged from the product discharge port 5. Water vapor generated in the container 15 during heating flows through the upper portion of the container 15 by a slight amount of carrier gas introduced from the carrier gas supply ports 2 and 4 and is continuously exhausted from the carrier gas exhaust port 3. . Further, moisture management of the dried product can be performed by controlling the temperature in the vicinity of the product discharge port 5 of the processed product staying in the dryer.

According to the present invention, the rotating blades 21 to 24 are rotated in the container 15 while being heated to 100 ° C. or higher, preferably 105 to 200 ° C., thereby continuously obtaining a dried product. If it is less than 105 ° C., it may be difficult to perform sufficient drying, and if it exceeds 200 ° C., the water-soluble cellulose ether may be thermally decomposed.
The heating of the rotor blade is preferably performed by flowing steam at atmospheric pressure or higher into the rotor blade that can contain the heat medium.

  The water content of the water-soluble cellulose ether to be added is 35 to 90% by mass. If it is less than 35% by mass, it tends to be overdried in the dryer, and the dried product may be burned. In some cases, the time required for drying may increase and efficient drying may not be possible.

The water content of the water-soluble cellulose ether to be added is preferably 35 to 50% by mass. When water-soluble cellulose ether having a water content of more than 50% by mass is put into the grooved agitator / dryer 10 as it is and dried, the water-soluble cellulose ether adheres to the parts and inner walls of the machine to form a film, and the heat transfer property May decrease, and the film may increase, making it difficult to continue the drying process. In such a case, it is preferable to adjust the water content to 35 to 50% by mass before introducing the water-soluble cellulose ether.
When it is necessary to adjust the water content to 35 to 50% by mass, this preparation may be performed by air drying. Heating of the dryer is preferably performed by flowing steam at atmospheric pressure or higher into the rotor blades 21 to 24 that can contain the heat medium.

  The water-soluble cellulose ether used in the present invention is not particularly limited, but is preferably at least one selected from the group consisting of methyl cellulose, hydroxypropyl methyl cellulose, and hydroxyethyl methyl cellulose.

  By making the temperature of the water-soluble cellulose ether charged into the dryer preferably 5 to 40 ° C., the property that the water-soluble cellulose ether is easily dissolved in a low temperature range can be utilized. It is preferable to dry after making it close to dissolution because water-soluble cellulose ether becomes a powder having good fluidity in the pulverization after drying. When this temperature is higher than 40 ° C., the water-soluble cellulose ether powder pulverized after drying may be bulky with poor fluidity. Moreover, if this temperature is less than 5 ° C., it takes time to raise the temperature and dry in the drying step, and efficient drying may not be performed.

  By controlling the temperature of the processed product in the container 15 of the grooved agitation dryer 10 used in the present invention, it is possible to prevent deterioration of quality due to excessive drying of the water-soluble cellulose ether and discharge of undried products. The amount of steam used can be reduced by 20 to 50% compared to when it is dried alone to the end.

EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to this.
Example 1
Hydroxypropyl methylcellulose having a substitution degree of methoxyl group of 1.45 and a molar degree of hydroxypropoxyl group of 0.185 was washed, and water was dehydrated to 55% by mass with a centrifuge. Both DS and MS indicate the number of substituents introduced per glucose unit.
Using a paddle dryer NPD1.6W type (total heat transfer area 2.7 m), which is a grooved stirring dryer manufactured by Nara Machinery Co., Ltd. While the rotor blades 21 to 24 were heated to 133 ° C., a dehydrated product of hydroxypropylmethylcellulose having a product temperature of 20 ° C. was supplied at 48 kg / hr and operated for 3 hours.
And the volume filling rate and water content of the hydroxypropyl methylcellulose were measured in the product discharge port in the state where the inside of the grooved stirring dryer was stable. As a result, the volume filling rate was 95% and the water content was 2% by mass.
When this was pulverized with a Victory Mill VP-1 manufactured by Hosokawa Micron Corporation, the pulverized product had good fluidity.

Comparative Example 1
After dehydrating the same hydroxypropyl methylcellulose as used in Example 1, the water content was adjusted to 30% by mass with an air dryer and the same apparatus as in Example 1 was used. It was supplied at 5 kg / hr.
The dried product was cotton-like, and when this was pulverized with a Victory Mill VP-1 manufactured by Hosokawa Micron Corporation, the pulverized product was cotton-like and extremely poor in fluidity.

Example 2
The same hydroxypropylmethylcellulose as in Example 1 and having a water content of 70% by mass was obtained. Using the same apparatus as in Example 1, a hydroxypropylmethylcellulose dehydrated product at a product temperature of 10 ° C. was supplied at 48 kg / hr, and the steam pressure was adjusted so that the product outlet 5 temperature was 131 ± 1 ° C. Then, the hydroxypropylmethylcellulose water content was measured at the product outlet while the inside of the grooved agitation dryer was stable. As a result, the water content was 2 ± 1% by mass. Further, no adhesion of hydroxypropylmethylcellulose was observed on the inner wall surface near the raw material supply port and in the dryer.

The following is described in the claims of the original application of the present application.
[Claim 1] A water-soluble cellulose ether having a water content of 35 to 90% by mass is continuously charged into a container of a grooved stir dryer, and the rotating blade is rotated while being heated to 100 ° C or higher in the container. And continuously drying the water-soluble cellulose ether.
[2] The method for drying a water-soluble cellulose ether according to [1], wherein the water-soluble cellulose ether added is 5 to 40 ° C.
[3] The method for drying a water-soluble cellulose ether according to [1] or [2], wherein the water content is 35 to 50% by mass.
[4] The method for drying a water-soluble cellulose ether according to any one of [1] to [3], wherein the heating of the rotor blades is performed by flowing steam at atmospheric pressure or higher into the rotor blades capable of containing a heat medium. .
[5] The water-soluble cellulose ether according to any one of [1] to [4], wherein the water-soluble cellulose ether is at least one selected from the group consisting of methylcellulose, hydroxypropylmethylcellulose, and hydroxyethylmethylcellulose. Method.

DESCRIPTION OF SYMBOLS 1 Raw material supply port 2 Carrier gas supply port 3 Carrier gas exhaust port 4 Carrier gas supply port 5 Product discharge port 6 Heat medium supply port 7 Heat medium discharge port 8 Steam supply port 9 Steam discharge port 10 Groove type agitation dryer 11 Upper cover 12 Lower jacket 13 External jacket 14 Space 15 Container 16 Hollow rotating shaft 17 Hollow rotating shaft 18 Gear 20 Thermometer with transmitter 21 Hollow rotating blade 22 Hollow rotating blade 23 Hollow rotating blade 24 Hollow rotating blade 25 Motor 26 Tube 27 Tube 28 Deficiency Part

Claims (2)

Water-soluble cellulose ether having a water content of 35 to 50% by mass with an air dryer is continuously charged into the vessel of the grooved agitation dryer, and steam at atmospheric pressure or more is introduced into the vessel to remove the rotor blades. It is a method for drying a water-soluble cellulose ether, characterized in that the water-soluble cellulose ether is continuously dried by rotating while being heated to 105 to 200 ° C.
The drying method of the water-soluble cellulose ether whose said water-soluble cellulose ether thrown in is 5-40 degreeC.   The method for drying a water-soluble cellulose ether according to claim 1, wherein the water-soluble cellulose ether is at least one selected from the group consisting of methylcellulose, hydroxypropylmethylcellulose, and hydroxyethylmethylcellulose.

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