KR100464168B1 - Method and apparatus for continuously extracting / neutralizing polymerization solvent and hydrochloric acid in aromatic polyamide polymer - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method and apparatus for continuously extracting / neutralizing a polymerization solvent and hydrochloric acid in an aromatic polyamide polymer.

2. The technical problem to be solved by the invention

In-polymerization that can efficiently neutralize the hydrochloric acid in the chip in weak base solution while efficiently removing the polymerization solvent present in the aromatic polyamide polymer chip after orientation to prevent corrosion of the device or deterioration of the pulp. It is intended to provide a continuous extraction / neutralization method of a solvent and hydrochloric acid and a device thereof.

3. Summary of Solution to Invention

The slurry solution of the aromatic polyamide polymer chip and the water-neutralizing agent cut to a certain size after the orientation was continuously supplied to the top of an upright cylindrical extraction / neutralization tower equipped with a stirrer, and then the aromatic polyamide polymer chip was rotated while rotating the stirrer. The slurry solution of water-neutralizing agent is contacted in parallel.

4. Important uses of the invention

Aromatic polyamide pulp produced by the process and apparatus of the present invention is used as an asbestos substitute for gaskets and brake linings.

Description

A method and apparatus for continuously extracting / neutralizing a polymerization solvent and hydrochloric acid in an aromatic polyamide polymer.

(1) the technical field to which the invention belongs and the prior art in that field

The present invention relates to a method and apparatus for continuously extracting / neutralizing a polymerization solvent and hydrochloric acid present in an aromatic polyamide polymer.

In general, the front-anionic polyamide fiber and its molded products have high strength, high elasticity, heat resistance, abrasion resistance, and electrical insulation, which are useful for special industrial fields such as composite materials and construction materials such as aircraft, automobile industry, leisure, and sporting goods. Is being used.

Aromatic polyamides are prepared by solution polymerization. That is, an aromatic diamine and an aromatic dieside chloride are prepared by reacting an inorganic salt alone or a polymerization solvent in which an inorganic salt and a Lewis acid compound are added to an amide solvent, a urea solvent, or a mixed solvent thereof.

Aromatic polyamide polymers for pulp are prepared by imparting orientation upon polymerization. As a method of imparting orientation in the polymerization process, Korean Patent Publications No. 90-4911 and Korean Patent Publication No. 92-4665 stir in a certain direction during polymerization, and in Korean Patent Publication No. 90-4911, the prepolymer is directed to a specific unit. After passing through and contacted with a tertiary amine, it is oriented, in Korean Patent No. 92-4665, the prepolymer is poured onto a belt and oriented using gravity and shear force,

In Korean Patent Laid-Open Publication No. 92-20018, an anisotropic polymer solution before gelation is continuously discharged into a container to be oriented and aged.

The aromatic polyamide polymer for pulp polymerized and oriented by the method described above is aged, cut into appropriate sizes, washed, crushed and dried to prepare an aromatic polyamide pulp. The aromatic polyamide polymer for pulp cut to a suitable size after polymerization, orientation and aging contains the polymerization solvent and alkaline earth metal salt used in the polymerization, and also contains a large amount of hydrochloric acid produced by the reaction of aromatic dieside chloride and aromatic diamine. It is.

In order to reuse the polymerization solvent and improve the quality of the pulp, the polymerization solvent must be efficiently extracted through a washing process. In addition, in order to prevent deterioration of the pulp properties due to hydrolysis of the polymer and corrosion of the apparatus, hydrochloric acid present in the polymer must be efficiently neutralized.

As a conventional technique for extracting a polymerization solvent in an aromatic polyamide polymer for pulp and neutralizing hydrochloric acid, a method of washing and neutralizing a predetermined time by introducing a polymer, washing water and a neutralizing agent into a batch washing tank, and separating the washing water and the polymer. Although this is known, there is a problem that the extraction efficiency of the polymerization solvent is low, and the polymerization solvent extraction time is long.

When preparing the aromatic polyamide pulp by pulverizing the polymer treated in this manner, the extraction efficiency of the polymerization solvent is low, so there is a high risk of powdering, and the quality of the pulp decreases. In addition, because the process is batch, continuous extraction of the polymerization solvent and neutralization of hydrochloric acid are impossible.

On the other hand, in a continuous extraction device such as a horizontal vacuum belt filter (Horizontal Vacumm Belt Filter), the method of extracting the polymerization solvent in the polymer and neutralizing hydrochloric acid by contacting the washing water and the neutralizing agent with the aromatic polyamide polymer in countercurrent. . Here, the countercurrent contact of the washing water and the neutralizing agent with the aromatic polyamide polymer means that the direction of travel of each other is opposite.

However, this method is not suitable because the extraction device is horizontal and sprays the washing water to the pulp chips on the belt, so that when the pulp chips are large, the extraction efficiency is low and a large number of extraction stages are required. Even in a straight cylindrical continuous extraction apparatus without a stirrer, when caustic soda, which is a strong base, is used, the polymer is hydrolyzed to degrade physical properties such as intrinsic viscosity of pulp.

In the prior art described above, all of caustic soda is used as a neutralizing agent, and thus the extract is liable to change into a strong base, which may cause hydrolysis of the polymer.

In the case of extracting the polymerization solvent present in the aromatic polyamide polymer chip cut after the orientation, the physical degradation due to the hydrolysis of the pulp is large in the strong basic solution state, so it is extracted in the weak basic solution state to efficiently remove the polymerization solvent. At the same time, it is an object of the present invention to provide a continuous extraction / neutralization method of a polymerization solvent and hydrochloric acid in a polymer capable of efficiently neutralizing hydrochloric acid present in a chip and a device thereof.

The present invention relates to a method and apparatus for continuously extracting / neutralizing a polymerization solvent and hydrochloric acid present in an aromatic polyamide polymer. More specifically, the present invention relates to a method and a device capable of more effectively extracting a polymerization solvent in a polymer in a weakly basic solution, neutralizing hydrochloric acid to prevent the pulp from deteriorating, and preventing corrosion of the device.

The extraction / neutralization method of the present invention is a continuous solution of an aromatic polyamide polymer chip cut to a certain size after orientation and a slurry solution of water and a neutralizing agent at the top of an upright cylindrical extraction / neutralization tower 7 provided with a stirrer 12 thereon. The aromatic polyamide polymer chip, a slurry solution of water and a neutralizing agent are brought into parallel contact with each other while rotating the stirrer 12 to continuously extract / neutralize the polymerization solvent and hydrochloric acid in the polymer chip.

By rotating the stirrer placed on top of the extraction / neutralization tower (7), the slurry solution of water-neutralizing agent is uniformly dispersed in the extraction / neutralization tower so that these slurry solutions are brought into uniform contact with the polymer chip.

The present invention uses a calcium hydroxide or calcium carbonate solution as a neutralizing agent. As a result, the recovery of the polymerization solvent is easy while preventing the degradation of the properties due to hydrolysis of the polymer compared to the use of caustic soda.

The aromatic polyamide polymer chip introduced into the extraction / neutralization tower 7 in the present invention has a particle size of 10 to 50 mm in width, 10 to 50 mm in length, and 5 to 10 mm in thickness. If the particle size is too large, the polymerization solvent extraction process takes a long time and the polymerization solvent extraction efficiency is also reduced. In addition, if the particle size is too small, there is a problem that the fine grinding in the grinding process after extraction.

In the extraction process of the polymerization solvent, it is preferable to adjust the conditions of the extraction process so that the weight ratio of the polymerization solvent present in the polymer chip to the weight of the dried aromatic polyamide polymer chip is 2.5 times or less.

When too much polymerization solvent remains in the polymer chip after extraction, the polymer chip is likely to be powdered in the grinding step.

The pH of the polymerization solvent extract is preferably adjusted to the input amount of the slurry solution to maintain the 4-7 level. When the pH of the polymerization solvent extract is out of the above range, the polymer is hydrolyzed to reduce pulp properties such as intrinsic viscosity.

The continuous extraction / neutralization apparatus of the present invention comprises (A) an upright cylindrical extraction / neutralization tower (7) provided with a stirrer (12) at the top, (B) an aromatic polyamide polymer installed at the top of the extraction / neutralization tower (7). A supply means of the chip, a slurry solution supply means of the water-neutralizing agent, and (C) a discharge means of the aromatic polyamide polymer chip provided at the bottom of the extraction / neutralization tower (7) and a discharge means of the polymerization solvent extract.

In the present invention, the supply means of the aromatic polyamide polymer chip is composed of an inlet 1 of the aromatic polyamide polymer chip and a screw feeder 2 for chip supply, and the slurry solution supply means of the water-neutralizing agent is a water-neutralizing agent. Slurry solution preparation tank (6), slurry solution supply tank (5), slurry solution metering tank (4) and slurry solution supply valve (3), the means for discharging the aromatic polyamide polymer screw feeder for chip discharge (9) and the chip discharge port 10, the discharge means of the polymerization solvent extraction liquid is composed of the polymerization solvent discharge port 11 and the drain screw feeder 8 for polymerization solvent extraction.

The present invention will be described in more detail with reference to the drawings.

1 is a process schematic diagram of continuously extracting / neutralizing a polymerization solvent and hydrochloric acid present in an aromatic polyamide polymer chip.

Aromatic polyamide polymer chips (hereinafter referred to as polymer chips) containing the polymerization solvent N-methyl pyrrolidone and hydrochloric acid (hereinafter referred to as polymer chips) are placed upright and cylindrical through the polymer chip inlet (1) and the screw feeder (2) for the chip feed. The upper end of the neutralization tower 7 is supplied.

Meanwhile a slurry solution of water and neutralizing agent (calcium hydroxide or calcium carbonate solution) is prepared in the production tank 6 and then extracted / neutralized through the supply tank 5, the metering tank 4 and the supply valve 3. Feed to the top of the tower (7).

Thus, the polymer chip and the water-neutralizing agent slurry solution supplied to the extraction / neutralization tower 7 fall into the bottom of the extraction / neutralization tower 7 while being brought into contact in parallel. In this process, the polymerization solvent present in the polymer chip is extracted by water, and hydrochloric acid is neutralized by a neutralizing agent. At this time, the stirrer 12 is installed at the top of the extraction / neutralization tower to disperse the slurry solution of the water-neutralizing agent so as to contact the polymer chip at a uniform concentration. The stirrer 12 type is suitably a paddle type stirrer.

The polymerization solvent extract is discharged from the reservoir through the drain screw feeder 8 for polymerization solvent extraction and the polymerization solvent extract outlet 11 to be recovered. At this time, the slurry solution of the water-neutralizing agent is appropriately adjusted so that the pH of the polymerization solvent extract is 4-7. The polymer chip subjected to extraction / neutralization is separated from the solution by the chip feed screw feeder 9 located at the bottom of the extraction / neutralization tower 7 and then transferred to the next step through the chip outlet 10 to the grinding process. do.

The conditions of the extraction process are adjusted so that the weight ratio of polymerized solvent in the polymer to the weight of the extracted / neutralized polymer is 2.5 times or less.

The extracted / neutralized polymer chip is crushed and then subjected to a secondary polymerization solvent extraction process. In the secondary polymerization solvent extraction step, it is preferable to contact the pulverized polymer with washing water (water) fragrance.

The washing water used in the secondary extraction process can be reused in the grinding process. Thus, the polymer which passed the secondary extraction process is pulped through the refining process.

The continuous extraction / neutralization method and apparatus of the present invention are first equipped with a stirrer 12 on top of the upright-cylindrical extraction / neutralization tower 7 so that the water-neutralizing agent slurry solution can be brought into uniform contact with the polymer chip. have.

As a result, the extraction and neutralization efficiency is improved, and the physical properties of the pulp are improved. In addition, a weakly basic calcium hydroxide or calcium carbonate solution is used in place of the conventional strong base caustic soda, so that the polymer can be hydrolyzed and the physical properties such as intrinsic viscosity can be prevented and the device corrosion is prevented. can do.

Hereinafter, the present invention will be described in detail through Examples and Comparative Examples.

However, the present invention is not limited only to the examples.

Example 1

An aromatic polyamide polymer chip was prepared by cutting an aromatic polyamide polymer having 9.3 Kg of N-methyl pyrrolidone to 1 Kg of dried oriented polymer and having an intrinsic viscosity of 4.12 by 30 mm in width, 30 mm in length and 10 mm in thickness. 150 Kg / hour speed at the top of the upright cylindrical extraction / neutralization tower 7 through the chip inlet 1 and the chip feeder feeder 2 as the extraction / neutralization apparatus of the present invention. To supply. Meanwhile a slurry solution of water-calcium hydroxide is prepared and then fed to the top of the extraction / neutralization tower 7 at a rate of 8 liters / hour.

The polymer chip supplied is rotated in parallel with the slurry solution while rotating the stirrer 2 of the extraction / neutralization tower 7 for extraction / neutralization.

At this time, the internal temperature of the extraction / neutralization tower 7 supplies steam to the jacket of the extraction / neutralization tower to maintain 60 ° C. The residence time of the polymer chip in the extraction / neutralization tower is adjusted to 8 hours. At the bottom of the extraction / neutralization tower, the polymerization solvent extract is discharged to the reservoir through the drain screw feeder 8 and the extract outlet 11.

At this time, the pH of the polymerization solvent extract was measured regularly, and the slurry solution input of water-calcium hydroxide was appropriately adjusted so that these values were in the range of PH 4-7.

The extracted / neutralized polymer chip is separated from the solution in the screw feeder 9 for chip discharging, and then transferred to the next process, which is a grinding process, through the chip outlet 10.

In this case, the polymer chips passing through the chip outlets were sampled five times at regular time intervals to analyze the content of N-methyl pyrrolidone remaining in the polymer chips. The polymer chips transferred to the grinding process are pulverized and the particle size distribution is 26.2% over 16 mesh, 40.1% between 16-30 mesh, 15.1% between 30-50 mesh, 9.3% between 50-100 mesh, 100-200 A polymer having 8.5% between meshes and 0.8% below 200 mesh is prepared. These polymers were slurried with 2 wt% of water in a slurry make-up bath and then continuously fed to the secondary continuous extraction unit at a rate of 143.05 Kg / hour, and at the end of the extraction unit, water was extracted at 460 Kg / hour. Fed to bring the polymer and water in countercurrent contact to secondary extraction of the N-methyl pyrrolidone remaining in the polymer. At this time, a 13-stage horizontal vacuum belt filter (HOROZONTAL VACUUM BELT FILTER) is used as the second continuous separator.

The content of N-methyl pyrrolidone in the prepared pulp is 0.76% by weight.

Comparative Example 1

The aromatic polyamide polymer chip was cut into 30 mm long, 30 mm long and 10 mm thick by cutting an aromatic polyamide polymer having 9.3 Kg of N-methyl pyrrolidone to 1 Kg of the dried oriented polymer and having an intrinsic viscosity of 4.12. The prepared and manufactured polymer chips are fed at a speed of 150 Kg / hour to the top of an upright cylindrical extraction / neutralization tower without a stirrer.

Meanwhile, an aqueous caustic soda solution is fed to the lower end of the extraction / neutralization tower 7 at a rate of 8 liters / hour, and the polymer chips are brought into contact with the caustic soda aqueous solution while flowing countercurrent to extract / neutralize. At this time, steam is supplied to the jacket of the extraction / neutralization tower to maintain 60 ° C as the internal temperature of the extraction / neutralization tower (7).

The residence time of the polymer chip in the extraction / neutralization tower is adjusted to 8 hours. The polymerization solvent extract is continuously discharged into the reservoir through the top of the extraction / neutralization tower.

At this time, the pH of the polymerization solvent extract was measured regularly, and the amount of caustic soda solution was adjusted appropriately so that these values were in the range of PH 4-7, but the pH of the extract was 2 because of difficulty in controlling the pH.

The extracted / neutralized polymer chip is separated from the liquid in the rotary drum separator and then moved to the next grinding step. In this case, the polymer chips passing through the chip outlets were sampled at regular time intervals to analyze the content of N-methyl pyrrolidone remaining in the polymer chips.

The polymer chip transferred to the grinding process was pulverized and the pulverized polymer was slurried with 2 wt% of water in a slurry make-up tank, and then continuously fed to the secondary continuous extraction apparatus at a rate of 143.05 Kg / hour, and the final part of the extraction apparatus. Is fed with water as an extractant at a rate of 460 Kg / hour to make the polymer and water contact in countercurrent to secondary extraction of N-methyl pyrrolidone remaining in the polymer.

At this time, 13 second horizontal vacuum belt filter (HOROZONTAL VACUUM BELT FILTER) is used. After the secondary extraction process, the polymer is refined and pulped. The content of N-methyl pyrrolidone in the prepared pulp is 2.3% by weight.

<Table 1> Measurement result of polymer solvent content remaining in polymer chip per 1 Kg of dry polymer chip after extraction / neutralization process in Example 1

Deterioration of the intrinsic viscosity of the polymer chip is 0.158 on average.

<Table 2> Measurement result of the polymerization solvent content remaining in the polymer chip per 1 Kg of the dry polymer chip after the extraction / neutralization process in Comparative Example 1

Deterioration of the intrinsic viscosity of the polymer chip is 0.66 on average.

The continuous extraction / neutralization method and apparatus of the present invention are first equipped with a stirrer 12 on top of the upright-cylindrical extraction / neutralization tower 7 so that the water-neutralizing agent slurry solution can be brought into uniform contact with the polymer chip. have.

As a result, the extraction and neutralization efficiency is improved, and the physical properties of the pulp are improved. In addition, since calcium hydroxide or calcium carbonate solution is used instead of caustic soda as a neutralizing agent, it is easy to control the pH, so that the polymer can be hydrolyzed and the physical properties such as intrinsic viscosity can be prevented. You can prevent it.

1 is a process schematic diagram of continuously extracting / neutralizing a polymerization solvent and hydrochloric acid in an aromatic polyamide polymer chip.

In FIG. 1, 1 is the inlet of the aromatic polyamide polymer chip, 2 is the screw feeder for the chip feed, 3 is the slurry solution supply valve of the water-neutralizing agent, 4 is the slurry solution metering tank of the water-neutralizing agent, 5 Is a slurry solution supply tank of water-neutralizing agent, 6 is a slurry solution preparation tank of water-neutralizing agent, 7 is an extraction / neutralization tower, 8 is a drain screw feeder for polymer solvent extraction, and 9 is a screw pump for chip evacuation Furthermore, 10 is the chip outlet, 11 is the outlet of the polymerization solvent extract, 12 is the stirrer of the extraction / neutralization tower, and M is the motor.

Claims (9)

The slurry solution of the aromatic polyamide polymer chip and the water-neutralizing agent cut to a certain size after the orientation is continuously supplied to the upper end of the upright cylindrical extraction / neutralization tower 7 provided with the stirrer 12 thereon, and the stirrer 12 A method of continuously extracting / neutralizing a polymerization solvent and hydrochloric acid in an aromatic polyamide polymer, comprising contacting the aromatic polyamide polymer chip with a slurry solution of water and a neutralizing agent in a co-current manner while rotating. The method of claim 1, wherein the neutralizing agent is a calcium hydroxide or calcium carbonate solution, wherein the polymerization solvent and hydrochloric acid in the aromatic polyamide polymer are continuously extracted / neutralized. The process according to claim 1, wherein the cut aromatic polyamide polymer chip has a particle size of 10 to 50 mm in width, 10 to 50 mm in length, and 5 to 10 mm in thickness. How to extract / neutralize. The method of continuously extracting / neutralizing the polymerization solvent and hydrochloric acid in the aromatic polyamide polymer according to claim 1, wherein the weight ratio of the polymerization solvent present in the polymer chip to the weight of the dried aromatic polyamide polymer chip after extraction is 2.5 times or less. The method for continuously extracting / neutralizing the polymerization solvent and hydrochloric acid in the aromatic polyamide polymer according to claim 1, wherein the slurry solution input of the water-neutralizing agent is adjusted so that the pH of the polymerization solvent extract is 4-7. (A) Upright cylindrical extraction / neutralization tower (7) having a stirrer (12) at the top, (B) Slurry of feed means and water-neutralizing agent of aromatic polyamide polymer chips provided at the top of the extraction / neutralization tower (7) Solution supply means and (C) Continuous extraction of the polymerization solvent and hydrochloric acid in the aromatic polyamide polymer, characterized in that it comprises a discharge means for the aromatic polyamide polymer chip installed at the bottom of the extraction / neutralization tower (7) and a discharge means for the polymerization solvent extract. Device to neutralize. The polymerization solvent and hydrochloric acid in the aromatic polyamide polymer according to claim 6, characterized in that the supplying means of the aromatic polyamide polymer chip comprises an inlet (1) of the aromatic polyamide polymer chip and a screw feeder (2) for chip feeding. Continuously extract / neutralize the device. The method of claim 6, wherein the means for discharging the aromatic polyamide polymer comprises a screw feeder 9 for discharging chips and a chip outlet 10 for continuously extracting / neutralizing the polymerization solvent and hydrochloric acid in the aromatic polyamide polymer. Device. The polymerization solvent and hydrochloric acid in the aromatic polyamide polymer according to claim 6, characterized in that the means for discharging the polymer solvent extract comprises a polymer solvent outlet 11 and a drain screw feeder 8 for polymer solvent extraction. Neutralizing device.