JPS59119172A - Method of drying gelled polymer containing water - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for drying a water-containing gel polymer that is water-soluble and highly adhesive.

More specifically, prior to drying a highly sticky hydrogel polymer, a hydrogel is extruded using a scree extruder, such as a meat grinder, equipped with a cutter that operates in substantial contact with the surface of the porous plate a. The polymers are cut with a cutter that operates in substantial contact with the outer surface of the perforated plate while being treated with a release agent to prevent mutual adhesion, and the small particles are dried in a rotary dryer to form small particles without mutual adhesion. Regarding how to.

Hydrous gel-like polymers obtained by aqueous solution polymerization, such as polymethacryloyloxyethyltrimethylammonium chloride, polymethacryloyloxyethyldimethylbenzyl chloride, polymethacryloyloxyethyldimethylammonium sulfate, polyacrylamide, polysodium acrylate, and these Copolymers of
When drying, the drying rate decreases at an accelerated rate as the water content decreases, because the rate of diffusion of internal moisture to the surface of the hydrogel polymer becomes dominant. Therefore,
In order to efficiently dry a hydrogel polymer, it is necessary to take measures to increase the surface area of the hydrogel polymer as much as possible during drying. That is, it is desirable to make it into small particles. For this purpose, a screw extruder equipped with a cutter that operates in substantial contact with the outer surface of the porous plate may be considered, but hydrogel polymers generally have an ultra-high molecular weight, so they do not touch the outer surface of the porous plate. In extruders with contact-actuated cutters,
The hydrogel polymer cannot be extruded unless the pressure is extremely high. However, if extruded under very high pressure, quality degradation such as breakage of polymer chains will occur. Therefore, it operates substantially in contact with the outer surface of the perforated plate.

Extrusion is practically impossible with a screw extruder equipped with a cutter. On the other hand, a hydrogel polymer can be extruded by using a fixed-screw IJ extruder, such as a meat grinder, equipped with a cutter that operates in substantial contact with the inner surface of the porous plate. That is, in order to extrude an ultra-high molecular weight material such as a hydrogel polymer, a screw extruder must be equipped with a cutter that operates in substantial contact with the inner surface of the porous plate.

However, since the hydrogel polymer is extremely sticky, if it is extruded using a meat grinder, it will be cut by a cutter that operates by substantially contacting the inner surface of the porous plate. Despite this, a string-like polymer is obtained that adheres to the front and back, and when these string-like polymers come into contact with each other from immediately after extrusion to the beginning of drying, strong adhesion occurs, forming a large lump that cannot be dried. Become. To prevent this adhesion, it is possible to coat the surface with a mold release agent. As a mold release agent for this purpose, silicone oil, surfactant, silicic acid fine powder, etc. are used. Even after treating the surface of the string-like polymer extruded from a meat grinder with these mold release agents to eliminate its stickiness, when attempting to dry the hydrogel-like polymer in a rotary dryer, this problem occurs. The string-like hydrogel polymers are entangled with each other and cannot be crushed into small particles until drying is completed, making it impossible to dry. Therefore, in order to dry uniformly in a rotary dryer, it is necessary to cut the string-like polymer into small pieces to prevent them from becoming entangled with each other.

Therefore, in order to uniformly dry a highly sticky hydrogel-like polymer in a rotary dryer, it is necessary to use a screw extruder equipped with a cutter that operates in substantial contact with the inner surface of the perforated plate.
For example, the surface of a string-like polymer extruded through a perforated plate such as a meat grinder must be treated with a release agent to prevent adhesion, and then the string-like polymer must be cut into small pieces with a cutter.

However, when attempting to perform the above operations separately, a screw extruder that operates by substantially contacting the internal interface of the perforated plate, such as a meat grinder, extrudes sideways, so the water-containing gel extruded from the perforated plate The polymers hang down and overlap each other, so even if a mold release agent is sprayed, it is difficult to uniformly coat the surface of the string-like hydrogel polymer.In particular, as the diameter of the porous plate becomes larger, the pores become larger. As the number increases, the number of overlapping parts increases, and the release agent is not uniformly coated on the surface, and adhesion occurs due to mutual contact, resulting in a lump that cannot be dried.

Therefore, by providing a cutter that operates in substantial contact with the outer surface of the perforated plate and immediately cutting the hydrous gel-like polymer extruded from the perforated plate, dripping and overlapping of the polymers can be eliminated. For this reason, when a mold release agent is sprayed, the surface of the extruded hydrogel polymer is uniformly coated, and at the same time, the mold release agent is divided into small pieces to prevent entanglement in a rotary dryer.

That is, the present invention provides a method for uniformly coating a release agent on the surface of a polymer extruded from a screw extruder, such as a meat grinder, equipped with a cutter that operates in substantial contact with the inner surface of a perforated plate. A cutter is provided that operates by substantially contacting the outer surface of the perforated plate, and by cutting with this cutter, the particles are made into small particles.
It is characterized by drying these small particles in a rotary dryer. Furthermore, as an additional effect of the present invention, the hydrogel polymer is shredded into small particles, which increases the surface area and enables efficient drying.

The present invention will be specifically explained using examples of polymethacryloyloxyethylammonium salts having high adhesive strength as representative examples of hydrogel polymers.

Example 1 After 5 ky of methacryloyloxyethyl trimethylammonium chloride and 5 ky of ion-exchanged water were thoroughly deoxidized with nitrogen gas 5 times, ammonium persulfate i, sg- , 1.8y of sodium thiosulfate was added to carry out polymerization.

The obtained hydrogel-like polymer was extruded using a meat grinder equipped with a perforated plate having a pore size of 7B (perforated plate diameter: 170 mm) and a cutter that operated in contact with the outer surface of the perforated plate.

During this extrusion, a silicone emulsion mold release agent (Shin-Etsu Chemical KM-741,) was sprayed onto the surface of the hydrogel polymer.
By cutting the particles into a length of about 7 mm with a cutter while treating the particles so that they would not stick even if they came into contact with each other, small particles that did not stick even if they came into contact with each other were obtained. This small particle has a diameter of 580
A triangular chevron-shaped scraping plate (
Hot air inlet speed 13 in rotary ventilation dryer with 20 equal distribution)
Drying was performed for 60 minutes at +n/sec hot air temperature 120°C.

As a result, a small granular polymer with an average water content of 10% and no tackiness was obtained.

Comparative Example 1 Extrusion 1.
It was dried. During extrusion, the outer surface of the perforated plate is not cut by a cutter, so a string-like gel is obtained that adheres to the front and back. When this string-like polymer is put into a rotary aeration dryer, due to the rotation,
They entangled with each other to form a lump and were not broken into small particles until the drying was completed, making it impossible to dry.

Comparative Example 2 Example 1 except that no silicone mold release agent was used to prevent adhesion
Extrusion drying was performed in the same manner as above. As a result, strong adhesion occurs when they come into contact with each other since there is no anti-adhesion protection. Therefore, they adhered to each other due to contact and became large cylindrical particles that could not be dried in the rotary ventilation dryer.

Example 2 Methacryloyloxyethyltrimethylammonium chloride 3.5ky, acrylamide 1.2kp.

After charging 7.2 kg of ion-exchanged water and thoroughly deoxidizing it with nitrogen gas, at a polymerization initiation temperature of 40°C, ammonium persulfate was 2.4 fi' and sodium thiosulfate was 2.4 fi'.
1 was added to carry out polymerization. The obtained hydrogel polymer was extruded and dried in the same manner as in Example 1.

As a result, small granular polymers with an average water content of 8% and no stickiness were obtained.

Comparative Example 3 Extrusion drying was performed in the same manner as in Comparative Example 1, except that the same hydrogel polymer as in Example 2 was used.

As a result, as in Comparative Example 1, the string-like glue became entangled with each other in the rotary aerated dryer, forming a lump that could not be dried.

Comparative Example 4 Extrusion drying was carried out in the same manner as in Comparative Example 2, except that the same hydrogel polymer as in Example 2 was used f].

As a result, as in Comparative Example 2, due to mutual adhesion due to contact, a cylindrical lump formed in the rotary aerated dryer and could not be dried.

Example 3 5ky of methacryloyloxyethyldimethylbenzyl ammonium chloride and 1 were added to 66 of ion exchange water,
After sufficiently deoxidizing with nitrogen gas, the polymerization initiation temperature was 35
℃, ammonium persulfate 1.8P as polymerization initiator
Polymerization was carried out by adding 1.8y- of sodium monothiosulfate. The obtained hydrogel polymer was extruded and dried in the same manner as in Example 1. As a result, a small granular polymer with an average water content of 10% and no tackiness was obtained.

Comparative Example 5 Extrusion drying was performed in the same manner as in Comparative Example 1, except that the same hydrogel polymer as in Example 3 was used.

As a result, as in Comparative Example 1, the string-like gel became a clump with each other (C) intertwined in the rotary aerated dryer and could not be dried.

Comparative Example 6 Extrusion drying was carried out in the same manner as in Comparative Example 2 except that the same hydrogel polymer as in Example 3 was used.

As a result, as in Comparative Example 2, due to mutual adhesion due to contact, a cylindrical lump formed in the rotary aerated dryer and could not be dried.

Patent applicant: Nippon Kayaku Co., Ltd.

Claims (1)

[Claims] extruding the hydrogel-like polymer with a scree extruder equipped with a cutter that operates in substantial contact with the inner surface of the porous plate;
A method for drying a hydrogel-like polymer comprising cutting it into small particles with a cutter that operates in substantial contact with the outer surface of a porous plate while being coated with a release agent, and drying the small particles in a rotary dryer. .