JPH043415B2 - - Google Patents

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to an apparatus for producing thermoplastic resin, and more particularly, to a method for producing a thermoplastic resin, and more specifically, a polymer powder having excellent powder properties without clogging of a polymer latex discharge nozzle. The present invention relates to a thermoplastic resin manufacturing apparatus capable of manufacturing.

[Technical background of the invention and its problems] In the polymer chemical industry, which manufactures resins, paints, adhesives, etc. through polymerization reactions, emulsion polymerization has been used as a method for producing resins with excellent functions, and in recent years, high value-added resins have been used. It is widely used in the polymerization process.

The manufacturing process in the emulsion polymerization method usually consists of a polymerization process, a coagulation process, a washing/dehydration process, a drying process, and a post-processing process, except when the final product is used in latex form such as paints and adhesives. .

It goes without saying that the polymerization process is important in the current situation where there is a strong demand for finer and functionalized resins. Since it has a large influence on the quality, it is also considered important from the viewpoint of quality, operability, and economy.

The coagulation process is a process in which the latex-like polymer obtained by polymerization undergoes a coagulation reaction with a coagulant to become a coagulated product, but the shape of the polymer obtained, that is, the powder properties, differs depending on the method. Obtaining a powder with characteristics such as uniform particle size, high bulk specific gravity, good dehydration properties, and good flowability is important for operability, workability, process stability, energy cost, and labor saving in the manufacturing process. This has great advantages in terms of security and safety.

Therefore, it is important to establish technology for the coagulation process as well as the emulsion polymerization process. However, conventional coagulation methods and coagulation apparatuses have not been able to obtain coagulated products with satisfactory powder properties, and therefore the development of coagulation techniques and coagulation apparatuses has been awaited. Below, the drawbacks of the prior art will be explained in detail.

Resin powder produced by conventional techniques was morphologically unstable, had a wide particle size distribution, and contained a mixture of fine powder and coarse particles, which caused many problems in handling. For this reason, various new coagulation methods have been investigated to improve workability, work environment, and safety, such as powder scattering, clogging in pipes and storage tank outlets, and the risk of powder explosion. Several methods have been proposed to improve powder properties. Typical examples include spray drying and spray coagulation.

These methods involve atomizing polymer latex and directly drying it or producing a coagulated product in a coagulating atmosphere, but since all of these techniques use a gas phase to fix the shape of the mist droplets, they require a lot of effort. This is a method that requires significant energy costs or construction costs for expensive equipment. In addition, the resulting powder has characteristics that are closer to a spherical shape than conventional coagulated materials, but the particle size is small and has characteristics similar to fine powder.

As mentioned above, the coagulation or drying method using the gas phase has a limit in controlling the mist diameter, and the maximum particle size is determined by itself, and there is still room for improvement in terms of powder shape. .

In addition, improving the conventional coagulation method or coagulation equipment is advantageous in terms of construction costs and operating costs, and is useful for developing methods to produce powder with the aforementioned excellent powder properties. has important significance.

[Objective of the Invention] An object of the present invention is to provide a thermoplastic resin manufacturing apparatus capable of manufacturing a polymer powder with excellent powder characteristics without clogging a polymer latex discharge nozzle. do.

[Summary of the Invention] The present inventors have made several proposals in accordance with the above-mentioned objectives, and as a result of intensive research based on the liquid phase solidification method proposed in Japanese Patent Application No. 73115/1982, the present inventors have made several proposals. , we have completed the device of the present invention.

That is, the liquid phase coagulation method developed by the present inventors does not require a gas phase region like the above-mentioned spray drying method or spray coagulation method, and can produce resin powder having an arbitrary particle size and excellent powder properties. can be manufactured. In other words, according to this liquid phase coagulation method, by changing the inner diameter of the thin tube that constitutes the polymer latex discharge nozzle, it is possible to obtain powder having a particle size ranging from several tens of micrometers to several millimeters. . The particle size distribution of the powder thus obtained has a narrow width, and there are few fine particles of several tens of micrometers or less, so it has excellent fluidity. Furthermore, the obtained powder fluid has a granular shape, has a large bulk specific gravity, and has good properties such as good dehydration properties when wet powder, and has characteristics that cannot be obtained by conventional wet coagulation methods. .

According to this liquid phase coagulation method, when an emulsion polymer latex is discharged into a coagulation liquid from a nozzle composed of a thin tube, the latex comes into contact with the coagulation liquid, coagulates with a coagulation reaction, and is shaped into a thread. It is discharged from the overflow port along with the flow of coagulation liquid. The shaped coagulated liquid is easily pulverized in a soft state and becomes granular to form a dispersion, so the flow of the coagulated liquid around the discharge nozzle has an important effect on operational safety and physical properties of the liquid. As a result of much research into the flow of the coagulating liquid and operational safety, the present inventors created a flow in which the coagulating liquid came into uniform contact with the polymer latex discharged from a discharge nozzle having a large number of thin tubes, and shaped the polymer latex. We have discovered a coagulation method that allows discharge of coagulum without accumulating it. In other words, if the flow of the coagulated liquid causes swirl-like turbulence around the discharge nozzle, the coagulated material accumulates at the tip of the discharge nozzle and becomes lump-like, making long-term operation impossible. Therefore, slowing down the flow around the discharge nozzle improves the transport state of the coagulated material around the nozzle. however,
The solidified material has a characteristic that its specific gravity increases with the passage of time, making it easier to settle. This is because the true specific gravity of the polymer is higher than that of the coagulation liquid, but in order to discharge the polymer with such properties from the coagulation tank without retention, the flow rate of the coagulation liquid towards the outlet of the coagulation tank must be increased. It would be better if you let it increase. In this way, the present inventors completed the following device.

That is, the thermoplastic resin manufacturing apparatus of the present invention comprises: a coagulation tank; a polymer latex discharge nozzle installed in the coagulation tank; a means for supplying a coagulation liquid into the coagulation tank; and a coagulated product of the polymer latex. A thermoplastic resin manufacturing apparatus comprising an overflow port provided in the coagulation tank for taking out the polymer latex, the coagulation liquid supply means supplying the coagulation liquid in the same direction as the polymer latex discharged from the discharge nozzle; The present invention is characterized in that a coagulating liquid supply means for supplying a coagulating liquid vertically upward to the polymer latex discharged from the discharge nozzle is installed in the coagulating tank.

The apparatus of the present invention will be explained in more detail based on the drawings.

FIG. 1 shows a preferred embodiment of the apparatus of the present invention, in which 1 is a coagulation tank, 2 is a polymer latex discharge nozzle disposed in the coagulation tank 1,
3 is a coagulating liquid supply means for supplying a coagulating liquid in the same direction as the polymer latex discharged from the discharge nozzle 2, and 4 is a coagulating liquid supplying means for supplying the coagulating liquid in a vertically upward direction of the polymer latex discharged from the discharge nozzle 2. A liquid supply means 5 includes an overflow port 6 provided in the coagulation tank 1 for taking out the coagulated product of polymer latex.
represents the bottom surface of the coagulation tank 1.

The coagulation tank 1 and the overflow port 5 may have any structure, but as shown in the figure, the bottom surface 6 of the coagulation tank
is preferably inclined upward from the installation site of the discharge nozzle 2 in the direction of the overflow port 5 at an angle of 1 to 45 degrees from the horizontal plane in order to achieve the effects of the present invention, and in this case, There is also the advantage that the coagulated material can be easily discharged even when the amount of coagulated liquid is reduced. Further, the bottom surface 6 of the coagulation tank may be made into a partition plate, and in this case, the inclination angle of the bottom surface 6 can be arbitrarily changed by the partition plate (not shown). on the other hand,
The discharge nozzle 2 may be any conventionally used one, but usually one in which several tens to several hundreds of thin tubes with a minute diameter are embedded in a disk is used.

The coagulating liquid supply means 3 is usually located opposite to the overflow port 5 with the discharge nozzle 1 in between,
Although it is installed on the side wall of the coagulation tank 1, its installation position is not particularly limited as long as the coagulation liquid can be supplied in the same direction as the polymer latex discharged from the discharge nozzle 2. Further, the coagulating liquid supply means 4 is usually provided on the bottom surface 6 of the coagulating tank and below the discharge nozzle 2, but it is provided in a vertically upward direction (perpendicular to the discharge nozzle) of the polymer latex discharged from the discharge nozzle 2. The installation position is not particularly limited as long as the coagulating liquid can be supplied in the upward direction. In the figure, coagulation liquid supply pipes are shown as the coagulation liquid supply means 3 and 4, but in the present invention, any means may be used as long as it can supply the coagulation liquid to the coagulation tank. Further, the number of means is not limited to one, and two or more may be used.
Furthermore, in the present invention, if necessary, a perforated plate having appropriate slits is provided slightly above the coagulating liquid supply means 4 to uniformly supply the coagulating liquid upward from the bottom surface 6 through the bottom outlet 7. (See Figure 2).

Next, a method of operating the apparatus of the present invention will be explained based on FIG. The coagulating liquid is supplied from the coagulating liquid supply means 3 and 4 to the coagulating tank 1 to fill the tank, and the polymer latex is supplied from the discharge nozzle 2 through the supply pipe 8 into the tank. The polymer latex is coagulated by contacting the coagulating liquid, and the purified coagulated product is discharged from the overflow port 5 and transferred to the solidifying tank 9.

[Effects of the Invention] By using the device of the present invention, it is possible to supply the coagulating liquid in the same direction as the polymer latex discharged from the discharge nozzle and in the vertically upward direction. The flow of coagulating liquid at is not obstructed. Therefore, the latex discharged from the nozzle becomes thread-like and the coagulated substances do not meet with each other, so the coagulated substances accumulate around the discharge nozzle, form a lump, and block the tip. This inconvenient situation is avoided. This effect becomes even more pronounced when a discharge nozzle with a large number of tubes is used to increase the throughput. Therefore, it may be possible to drive the coagulation process for a long time. Furthermore, since the resin powder obtained using the apparatus of the present invention has good powder characteristics, it can be said that the apparatus of the present invention brings great industrial benefits.

[Embodiments of the Invention] Example 1 A coagulating liquid supply means for supplying coagulating liquid in the same direction as the discharge direction of latex and in a vertically upward direction, and a 300 mm wide plate provided with a 100 mm wide perforated plate having a 10 mm slit at the bottom. , depth 400mm, flow
The coagulation operation was carried out using a coagulation tank as shown in Fig. 1 with a diameter of 1500 mm and a bottom slope of 15 degrees. A 0.5% sulfuric acid aqueous solution was used as the coagulation liquid during operation, and was supplied to the coagulation tank at a rate of 250/min.
Incidentally, the rate of supply of the coagulating liquid in the vertically upward direction relative to the discharged latex was 50/min.

The discharge nozzle is a disk with an outer diameter of 180 mm, in which 450 thin tubes with an outer diameter of 3 mm, an inner diameter of 0.8 mm, and a flow rate of 70 mm are embedded. It was installed in the coagulation tank so that the directions were the same. Next, a polymer latex obtained from 30 parts of butadiene, 21 parts of acrylonitrile, and 49 parts of styrene as monomer components was flowed into the nozzle at a rate of 5.5/min.
The polymer latex discharged from the discharge nozzle was coagulated while coming into contact with the coagulation liquid. The coagulated polymer latex was discharged from the overflow port along with the flow of the coagulating liquid. The discharged polymer moves without accumulation,
No coagulum accumulated in the discharge nozzle even after long-term operation.

Next, this was transferred to a solidification tank maintained at an internal temperature of 90°C, and the polymer was solidified by heating, followed by centrifugal dehydration, and then thoroughly dried in a box-type dryer to obtain granular thermoplastic resin powder. .

The characteristic values of the powder were as follows: average particle diameter was 0.84 mm, bulk specific gravity was 0.48, and fluidity index was 93. The amount that passed through the 250-mesh standard sieve was 0.21% of the total amount, and powder with extremely low fines was obtained.

Comparative Example 1 10 ml of 1% sulfuric acid aqueous solution was placed in a stirred tank with a baffle having a capacity of 50 ml, and while stirring and raising the temperature to 65°C, 15 ml of the same polymer latex as in Example 1 was gradually added dropwise to solidify the latex. . When the dropping was completed, the temperature of the stirring tank was raised to 95°C to solidify the polymer, and then a wet powder of the polymer was obtained using a centrifugal dehydrator. This method is a conventional batch coagulation method for polymer latex. Next, the obtained wet powder was sufficiently dried in a drier to obtain a dry powder, and the powder characteristics of the powder were evaluated.

As a result, the average particle diameter was 0.33mm, and the bulk specific gravity was
The amount passing through the 0.37, 250 mesh standard sieve is 3.5% of the total.
It was found that the powder had a fluidity index of 74 and had more fine powder than Example 1 and had poor fluidity.

Example 2 A coagulation bath having the same shape as in Example 1 was used to carry out the coagulation operation. Butadiene 70 as a monomer component
10 parts of methyl methacrylate and 20 parts of styrene was used. A 0.3% sulfuric acid aqueous solution was used as the coagulation liquid.
This is passed through the coagulation tank at a flow rate of 300/min,
The rate of supply of the coagulating liquid vertically upward relative to the discharged latex was 100/min.

The discharge nozzle is a 180mm disk with an outer diameter of 3mm.
7500 thin tubes with an inner diameter of 1 mm and a flow rate of 90 mm were used, and they were placed in the coagulation tank so that the flow of the coagulating liquid in the horizontal direction with respect to the discharged latex coincided with the discharge direction of the polymer latex. , the polymer latex was flowed through the nozzle at a rate of 9/min. As a result, the latex discharged from the discharge nozzle coagulated while coming into contact with the coagulating liquid. The coagulated polymer was discharged from the coagulation tank along with the flow of the coagulation liquid. At this time, the polymer discharged from the nozzle was discharged smoothly without accumulation, and the latex discharge condition was very stable.

This polymer was transferred to a solidification tank whose internal temperature was kept at 88°C, solidified by heating, centrifugally dehydrated, and thoroughly dried in a box dryer to obtain granular thermoplastic resin powder. Ta.

When the characteristic values of the powder were measured, the average particle diameter was
It was 0.96 mm, bulk specific gravity was 0.52, and fluidity index was 94. The amount passing through the 250 mesh standard sieve is 0.15% of the total amount.
It was found that the powder contained very little fine powder and had good fluidity.

Comparative Example 2 Example 2 except that the coagulating liquid was not supplied vertically upward to the discharged latex.
The coagulation operation was carried out in the same manner as above.

As a result, it was found that the latex discharged from the discharge nozzle had a string-like shape in the part where there was sufficient contact with the coagulating liquid, but in the part where the flow of the coagulating liquid was small, the latex was in the form of a lump, and as a result, the discharge of the coagulated material was difficult. As a result, the discharge nozzle gradually became clogged, making operation impossible. When the discharge nozzle was removed from the coagulation liquid and observed, uncoagulated latex was found to be attached to the tip of the nozzle embedded in the center of the nozzle disk. This phenomenon is thought to be due to the latex not being able to sufficiently contact the coagulating liquid.

Example 3 A coagulating liquid supply means for supplying coagulating liquid in the same direction as the latex discharge direction and vertically upward direction, and a 5 mm perforated plate at the bottom, width 150 mm,
The coagulation operation was carried out using a coagulation tank as shown in Fig. 1 having a depth of 200 mm, a flow rate of 1000 mm, and a bottom slope of 10 degrees. A 0.5% aqueous magnesium sulfate solution was used as the coagulation liquid during operation, and was supplied to the coagulation tank at a rate of 32/min. Incidentally, the rate of supply of the coagulating liquid in the vertically upward direction relative to the discharged latex was 10/min.

The discharge nozzle is a disk with an outer diameter of 90 mm and an outer diameter of 3 mm and an inner diameter.
95 thin tubes each having a diameter of 1.2 mm and a length of 100 mm were embedded in the coagulation tank so that the flow of the coagulation liquid in the horizontal direction with respect to the latex to be produced coincided with the discharge direction of the polymer latex. Next, 12 parts of butyl acrylate was added to the nozzle as a monomer component,
1.2 parts of a polymer latex obtained from 8 parts of ethyl acrylate, 60 parts of methacrylic acid and 20 parts of styrene.
/min. The polymer latex discharged from the discharge nozzle was coagulated while coming into contact with the coagulation liquid. The coagulated polymer was discharged from the overflow port along with the flow of the coagulating liquid. The discharged polymer moved without accumulation, and no coagulum accumulated in the discharge nozzle even after long-term operation.

Next, this was transferred to a solidification tank maintained at an internal temperature of 85°C, and the polymer was solidified by heating, followed by centrifugal dehydration, and then sufficiently dried in a box-type dryer to obtain granular thermoplastic resin powder. .

The characteristic values of the powder were as follows: average particle diameter was 1.15 mm, bulk specific gravity was 0.54, and fluidity index was 95. The amount that passed through the 250-mesh standard sieve was 0.10% of the total amount, and a powder with very little fine powder was obtained.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of the apparatus of the present invention, and FIG. 2 is a schematic diagram showing the flow of material during a coagulation operation using the apparatus of the present invention. 1... Coagulation tank, 2... Polymer latex discharge nozzle, 3... Coagulation liquid supply means for supplying a coagulation liquid in the same direction as the polymer latex discharged from the discharge nozzle, 4... Discharged from the discharge nozzle. Coagulation liquid supply means for supplying a coagulation liquid vertically upward of the polymer latex, 5... Overflow port, 6... Bottom surface of coagulation tank, 7... Bottom outlet, 8... Supply pipe, 9...
...Solidification tank.

Claims (1)

[Scope of Claims] 1. A coagulation tank; a polymer latex discharge nozzle installed in the coagulation tank; means for supplying a coagulation liquid into the coagulation tank; A thermoplastic resin manufacturing apparatus comprising an overflow port provided in a tank, comprising: a coagulating liquid supply means for supplying a coagulating liquid in the same direction as the polymer latex discharged from the discharge nozzle; 1. An apparatus for producing a thermoplastic resin, characterized in that the coagulating tank is provided with a coagulating liquid supply means for supplying the coagulating liquid vertically upward of the polymer latex. 2. The thermoplastic resin manufacturing apparatus according to claim 1, wherein the bottom surface of the coagulation tank is inclined from a horizontal plane by 1 to 45 degrees upward from the discharge nozzle installation site toward the overflow port.