JP3001401B2 - Powdering method of cellulose ether and powdering apparatus of 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 pulverizing cellulose ether used as a thickener for various solvents, a binder in an extrusion molding method, and an apparatus for pulverizing cellulose ether.

[0002]

2. Description of the Related Art Cellulose ether is obtained by etherifying hydroxyl groups of cellulose to make it water-soluble. Powdered cellulose ethers, which are obtained by pulverizing cellulose ether, are used in large quantities in many fields as thickeners for paints and emulsions, building materials for cement extrusion, mortar admixtures, turbidity agents for polymerization, binders for ceramic extrusion, etc. .

[0003] As a method of using powdered cellulose ether, there are a method of dissolving in a solvent such as water and adding it to a substrate, and a method of mixing with a substrate and then adding a solvent such as water and kneading. In the latter method, it is necessary to dissolve and mix easily in a short time, so that the powdered cellulose ether is required to have a small average particle diameter, a high bulk density, and a high viscosity when converted into an aqueous solution. In order to further reduce the amount of powdered cellulose ether used, 10%
High viscosity of 000 mPa · s or more may be required.

[0004] Cellulose ether is produced as follows. After adding aqueous sodium hydroxide or potassium hydroxide as a reaction catalyst to purified high-purity cotton linter pulp or wood pulp cellulose, methyl chloride is used for methoxyl substitution, and ethyl chloride is used for ethoxyl substitution. Ethylene oxide for hydroxyethyl group substitution, propylene oxide for hydroxypropoxyl group substitution, and monochloroacetic acid for carboxymethyl group substitution.
To react.

The obtained cellulose ether is purified by washing after removing sodium, potassium, alcohol and glycols generated during the reaction. Then, after drying to reduce the water content to 10% by weight or less, the mixture is pulverized by a pulverizer to obtain a powdered cellulose ether.

[0006] The raw material cellulose has a fibrous or flocculent shape, and it is difficult to produce a highly viscous cellulose ether when producing a high-viscosity cellulose ether because the shape is maintained until the drying step. Was.

To grind cellulose ether, a method using a cutter mill utilizing shear force, a method using a hammer mill utilizing impact force, and a method using a medium mill such as a tube mill or a vibration mill are widely used. Is being done.

When the cellulose ether is pulverized by a cutter mill, the particle size of the resulting powdered cellulose ether becomes large. When a hammer mill is used, particles having a small particle size can be obtained. However, the bulk density is not more than 0.25 g / cc and the fluidity is low. Poor productivity.
When a media mill is used, the residence time during pulverization is long, so that the viscosity is drastically reduced.

[0009]

On the other hand, when cellulose ether is pulverized using a rigid roller mill,
It can be pulverized efficiently, has high bulk density, and has little decrease in viscosity when converted to an aqueous solution. However, when the cellulose ether is pulverized with a rigid roller mill, the shape of the pulverized cellulose ether becomes acicular.
It was difficult to powder the powder to a bulk density of about 0 μm and a bulk density of 0.27 g / cc or more.

[0010] The present invention has been made to solve the above-mentioned problems, and the powdered cellulose ether after pulverization has good fluidity, a small average particle size, a high bulk density, and a reduced viscosity when converted to an aqueous solution. It is an object of the present invention to provide a method for pulverizing cellulose ether and a pulverization apparatus for cellulose ether.

[0011]

According to the method for pulverizing cellulose ether of the present invention which has been made to achieve the above-mentioned object, as shown in FIG. The table 2 has a rotating circular table 2 and a cross-sectional shape that matches the shape of the concave portion 4 of the table 2.
In grinding the fibrous cellulose ether raw material in the gap between the roller 5 having the rotation axis direction in the rotation radiation direction,
At least one of the grooves 6 in the rotation radial direction in the concave portion 4 of the table 2 and the grooves 9 (see FIG. 2) in the same direction as the radial direction on the surface of the roller 5 facing the table 2. Grind in the gap with 6.

The cellulose ether is preferably at least one selected from the group consisting of methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, hydroxyethylmethylcellulose, hydroxyethylethylcellulose and carboxymethylcellulose.

As shown in FIG. 1, the apparatus for pulverizing cellulose ether of the present invention, which has been made to achieve the above object, comprises a rotary circular table 2 having a concave portion along the rotational direction on the table 2, and A roller 5 having a cross-sectional shape matching the shape of the concave portion 4 of the table 2, having a rotation axis direction in the rotation radial direction of the table 2, and having a roller 5 disposed close to the table 2; , At least one of the groove 6 in the rotating radial direction in the concave portion 4 of the table 2 and the groove 9 in the same direction as the radial direction on the surface of the roller 5 facing the table 2 (see FIG. 2). Groove 6.

[0014]

As shown in FIG. 1, when cellulose ether is crushed between the rotary circular table 2 having the groove 6 and the roller 5, the crushed powdered cellulose ether is pulverized into a spherical shape without becoming acicular. Therefore, a powdered cellulose ether having a high bulk density is obtained. In addition, the air sent into the powdering device 10 quickly exhausts the powdered cellulose ether to the outside of the powdering device 10 and avoids excessive pulverization, so that a decrease in viscosity is suppressed. Since there is no contact between the rotary circular table 2 and the roller 5, there is almost no vibration or noise, and there is no possibility of dust explosion.

[0015]

Embodiments of the present invention will be described below in detail.

FIG. 1 is a schematic view showing an embodiment of a cellulose ether powdering apparatus 10 to which the present invention is applied.

The powdering device 10 grinds the fibrous cellulose ether raw material between the concave portion 4 of the turntable 2 and the roller 5 in the container 1 and blows up the powdered powdered cellulose ether to the upper part to thereby grind the container 1. It is a device that discharges to the outside.

A turntable 2 is arranged at a lower portion in the container 1, and the turntable 2 is connected to a motor 3 so as to rotate. The turntable 2 has a concave portion 4 along the rotation direction, and the concave portion 4 has a feed groove 6 in the rotational radial direction. A roller 5 having a cross-sectional shape matching the shape of the concave portion 4 is arranged close to the concave portion 4 in a non-contact manner. The width of the feed groove 6 decreases toward the outer periphery of the turntable 2. The roller 5 has a rotation axis direction in the rotation radiation direction of the turntable 2, is connected to the arm 14, and is pushed down toward the recess 4.

In the upper part of the container 1, a separator 7 for separating the pulverized powdered cellulose ether from the unpulverized fibrous cellulose ether raw material is disposed. The separator 7 has a rotating shaft 8. The rotating shaft 8 is connected to a motor 12 outside the container 1 to rotate the separator 7. Further, a raw material supply port 11 for feeding a fibrous cellulose ether raw material into the container 1 by a screw at a side portion of the container 1, a product outlet 15 for discharging pulverized powdered cellulose ether at an upper portion of the container 1, and a container at a lower portion of the container 1. 1
An air supply port 20 for sending air into the inside and a foreign substance discharge port 13 for discharging foreign substances such as metal pieces are provided.

Using this powdering apparatus 10, a fibrous cellulose ether raw material is powdered as follows. When the fibrous cellulose ether raw material is put into the container 1 through the raw material supply port 11, the fibrous cellulose ether raw material falls on the turntable 2 and is accumulated in the concave portion 4 by the centrifugal force of the turntable 2.
The accumulated fibrous cellulose ether raw material is supplied to the roller 5
While being compressed and ground between the and the recess 4, the powder is spherically powdered by the groove 6 and moves toward the outer periphery of the turntable 2. The roller 5 rotates by being pressed against the fibrous cellulose ether raw material.

The inside of the container 1 is cooled by the swirling airflow generated by the air sent from the air supply port 20, and at the same time, the crushed powdered cellulose ether rides on the swirling airflow and rises to the upper part inside the container 1. . At this time, the unmilled fibrous cellulose ether raw material also rises to the upper part in the container 1, but only the powdered cellulose ether enters the slit of the separator 7 and is classified, and the product outlet 1 along with the air flow is classified.
5 is discharged to the outside of the container 1. The discharged cellulose ether is collected by a dust collector such as a bag filter. The unmilled fibrous cellulose ether raw material falls onto the turntable 2 and is powdered again. In addition, foreign substances such as coarse particles and metal pieces that cannot be transported by airflow are discharged from the foreign substance discharge port 13.

FIG. 2 is an enlarged view of a main part showing another embodiment of a cellulose ether powdering apparatus to which the present invention is applied. This powdering device has the same structure as that of the powdering device 10 shown in FIG. 1 except that a feed groove 9 in the rotation radial direction of the turntable 2 is provided on the surface of the roller 5 facing the table 2. It has the same configuration and operates in the same manner as the powdering device 10.

The fibrous cellulose ether raw material was powdered under the following conditions.

First, hydroxypropyl methylcellulose was produced as a fibrous cellulose ether raw material. For high purity cotton linter pulp, sodium hydroxide,
Methyl chloride for methoxyl group substitution and propylene oxide for hydroxypropoxyl group substitution are added and reacted, and purified with hot water until the residual salt content of hydroxypropyl methylcellulose becomes about 1% by weight, and then dried. A fibrous hydroxypropyl methylcellulose raw material having a water content of 1.2% by weight was obtained. This fibrous hydroxypropyl methylcellulose raw material had a methoxyl substitution degree of 1.4 and a hydroxypropoxyl group substitution degree of 0.2. The degree of substitution indicates the number of substituents introduced per glucose unit.

The obtained fibrous hydroxypropylmethylcellulose raw material was made into an aqueous solution having a concentration of 1% by weight, kept at a constant temperature of 20 ° C., and the viscosity was measured by using a block field type rotational viscometer. The viscosity was 16750 mPa · s.
The average particle size is the nominal size 1000, 710, 500, 355, 250, 18 specified in JIS Z8801.
It was 505 μm when measured using a sieve of 0, 150, 106 μm. The bulk density was 0.46 g / cc.

An IHI fine-pulverized hard mill (IS-250 type mill: manufactured by Ishikawajima-Harima Heavy Industries Co., Ltd.)
Feed groove 6 in both turntable 2 and roller 5
9, a device having a feed groove 6 only in the turntable 2 and a device having a feed groove 9 only in the roller 5 are each charged with a fibrous hydroxypropylmethylcellulose raw material and pulverized. Propylmethylcellulose was collected with a bag filter.
The distance from the center of the turntable 2 to the radial center of the recess 4 was 250 mm, the minimum width of the feed groove 6 was 1 mm, and the maximum width was 5 mm.

The average particle size and the bulk density of the obtained powdered hydroxypropylmethylcellulose were measured, and the viscosity was measured by adding the powdered hydroxypropylmethylcellulose to an aqueous solution having a concentration of 1% by weight. The results are shown in Table 1 as characteristics of powdered hydroxypropyl methylcellulose.

[0028]

[Table 1]

As shown in Table 1, when an apparatus having feed grooves 6.9 in either the turntable 2 or the roller 5 is used, the average particle diameter is about 70 μm and the bulk density is 0.27 g. / Cc or more, there was little decrease in viscosity. Feed grooves 6 in both the turntable 2 and the roller 5
9 is used, the feed grooves 6.9 are provided on one side.
, The average particle size was smaller, the bulk density was higher, and the decrease in viscosity was less.

For comparison, an IHI pulverizing hard mill having no feed grooves 6.9 in both the turntable 2 and the roller 5 was used, and an ACM pulperizer (ACM) was used.
-15W: Hosokawa Micron Co., Ltd., Victor Mill (VP-1: Hosokawa Micron Co., Ltd.), Batch Vibration Mill (B-3: Chuo Kakoki Co., Ltd.) and Ball Mill (Kurimoto Iron Works Co., Ltd.) Thus, the fibrous hydroxypropyl methylcellulose raw material was pulverized.

The average particle diameter and the bulk density of the obtained powdery hydroxypropylmethylcellulose were measured, and the viscosity was measured by adding the powdery hydroxypropylmethylcellulose to an aqueous solution having a concentration of 1% by weight. The results are shown in Table 1 as characteristics of powdered hydroxypropyl methylcellulose.

As shown in Table 1, neither the turntable 2 nor the roller 5 has an IH having feed grooves 6.9.
Powdered hydroxypropylmethylcellulose powdered by a fine milling hard mill had a small average particle size, but had a low bulk density and a large decrease in viscosity. Those powdered with the ACM pulperizer had a large average particle diameter, a low bulk density, and a large decrease in viscosity. The powder obtained by powdering with Victor Milli had a small decrease in viscosity, but had a large average particle size and a small bulk density. Powdered powders produced by a batch vibration mill and a ball mill had a small average particle size and a large bulk density, but had a significantly large decrease in viscosity.

[0033]

As described in detail above, when cellulose ether is pulverized by the method and apparatus of the present invention, the powdered cellulose ether after pulverization has a good fluidity, a small average particle diameter and a high bulk density. In addition, there is little decrease in viscosity when converted to an aqueous solution. Moreover, the working environment is good with less vibration and noise of the powdering device.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of a cellulose ether powdering apparatus to which the present invention is applied.

FIG. 2 is a main part enlarged view showing another embodiment of a cellulose ether powdering apparatus to which the present invention is applied.

[Explanation of symbols]

1 is a container, 2 is a turntable, 3 and 12 are motors, 4
Is a recess, 5 is a roller, 6 and 9 are feed grooves, 7 is a separator, 8 is a rotating shaft, 10 is a powdering device, 11 is a raw material supply port, 13 is a foreign substance discharge port, 14 is an arm, and 15 is a product discharge port. , 20 are air supply ports.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI C08L 1:00 (72) Inventor Yukio Tamura 28 Nishifukushima, Oku, Kushiro-mura, Nakakubijo-gun, Niigata Shin-Etsu Chemical Co., Ltd. In the laboratory (56) References JP-A-2-235901 (JP, A) JP-A-3-86255 (JP, A) JP-A-4-348130 (JP, A) JP-A-6-256528 (JP, A A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B29B 13/10 B02C 15/00-15/16 C08B 11/00-11/22 C08J 3/12

Claims (3)

(57) [Claims] 1. A gap between a rotary circular table having a concave portion along a rotation direction on a table and a roller having a cross-sectional shape matching the concave shape of the table and having a rotation axis direction in a rotation radial direction of the table. At the time of grinding the fibrous cellulose ether raw material, at least one of the grooves in the direction of rotation in the concave portion of the table and the grooves in the same direction as the radial direction on the surface of the roller facing the table. A method for pulverizing cellulose ether, characterized by grinding in a gap having a groove. 2. The method according to claim 1, wherein the cellulose ether is at least one selected from methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, hydroxyethylmethylcellulose, hydroxyethylethylcellulose and carboxymethylcellulose. A method for pulverizing the cellulose ether according to claim 1. 3. A rotating circular table having a concave portion along the direction of rotation on the table, having a cross-sectional shape matching the concave shape of the table, having a rotation axis direction in the direction of rotation of the table, and approaching the table. And a roller arranged in the cellulose ether powdering apparatus, wherein the groove in the rotation radial direction in the recess of the table, and the surface of the roller facing the table in the same direction as the radial direction. An apparatus for pulverizing cellulose ether, comprising at least one of the grooves.