JPH0147482B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a polymerization system in which an anti-scaling agent coating device is installed at each feed raw material pipe of a polymerization vessel, a condenser attached to a polymerization vessel, or an attachment port of these polymerization vessels. Regarding equipment.

Conventionally, known methods for polymerizing monomers such as vinyl monomers or diene monomers include suspension polymerization, emulsion polymerization, solution polymerization, gas phase polymerization, and bulk polymerization. However, in all of these polymerization methods, there was a problem of polymer scale adhesion on the inner walls of the polymerization vessel, the stirring device, and the like.

In other words, when vinyl monomers are polymerized using these methods, polymer scale is deposited on the inner walls of the polymerization vessel and parts of the polymerization vessel that come into contact with the monomers, such as the stirring device, which reduces the yield of the polymer and the cooling capacity of the polymerization vessel. In addition to this, this scale flakes off and mixes into the product, degrading the quality of the product. On the other hand, removing this scale requires excessive labor and time. Not only that, but unreacted monomers are adsorbed in this scale, so there is a disadvantage that there is a risk of human injury due to monomers (vinyl chloride, etc.), which has become a very serious problem in recent years. There is.

In order to solve this problem of scale adhesion, it has been known to apply a scale preventive agent to the inner wall of the polymerization vessel, the stirring device, etc. A method of applying an organic compound, dye, or pigment, a method of applying a polar organic compound or dye treated with a metal salt, a method of applying a mixture of an electron donating compound and an electron accepting compound, or a method of applying a sulfonic acid type. Alternatively, a method is known in which an aqueous solution in which an alkali metal or ammonium salt of a carboxylic acid type dye is dissolved is adjusted to a pH of 7 or lower and then applied.

However, scale adhesion is not limited to polymerization vessels.
It also occurs in equipment that comes into contact with gaseous monomers, such as condensers, piping for each raw material, and the installation ports of these in polymerization vessels. Applying scale preventive agent to these areas can also prevent scale adhesion, but this requires removing the flanges from those areas before applying the scale preventive agent, which is a hassle. It is also virtually impossible to fully fill these areas with a scale inhibitor.

For this reason, the current situation is that scale preventive agents are applied to these areas once every few dozen batches, and by the time scale is applied once every few dozen batches, scale has already adhered, so it is necessary to apply the anti-scaling agent once every few dozen batches. Cleaning must be done to remove scale, and this work requires excessive labor and time.

On the other hand, as the risk of injury to the human body due to monomers has become a serious problem, there is a strong demand for closed system operation, or at least operation using an automatic coating method.

In order to satisfy such demands, the present invention was developed as a result of intensive research, and was developed by providing a short pipe with the other end closed with a flange in the feed material piping of the polymerization vessel, the condenser, or the attachment port of these polymerization vessels. We have developed a polymerization device in which a scale inhibitor coating device equipped with a pressure shower type spray nozzle or a drill hole nozzle is installed in the center of the polymerization device.

According to the present invention, the desired application operation can be performed by automatically applying the scale inhibitor in a short period of time, from several seconds to several tens of seconds, without removing the flange or the like. Since this operation is carried out in a closed system, the scale-inhibiting agent coating operation, which is carried out every polymerization batch or every few batches, can be carried out very easily and safely, and an excellent scale-preventing effect can be obtained.

The present invention will be explained in detail below.

The scale preventive agent coating device installed in the polymerization apparatus of the present invention supplies the scale preventive agent (liquid) prepared in advance to this coating device using a pump, etc. to coat the internal surfaces of the condenser and the polymerization vessel. A coating film of an anti-scaling agent is formed on the inner surface of the raw material pipes or the attachment ports of these polymerization vessels. FIG. 1 shows an outline of this system, in which 1 is a polymerization vessel, 2 is a condenser, 3 is a mounting port, and 4 is a scale inhibitor coating device, which are installed at five locations in the drawing. Reference numeral 5 indicates a tank for storing a scale preventive agent, 6 indicates a pump, and 7 indicates a raw material supply pipe, which is connected to the attachment port 3 together with the condenser 2.

FIG. 2 is a cross-sectional view of the coating device, where 8 is a flange and 9 is a nozzle attached to the center of this flange. The nozzle type can be either a pressure shower type spray nozzle or a drilled hole.
As the pressure shower type spray nozzle, a fan-shaped nozzle, a descaler nozzle, a full cone nozzle, an empty cone nozzle, a straight nozzle, a tank drum cleaning nozzle, etc. are used.

The diameter of droplets ejected from the nozzle is preferably 1000μ or more. If the diameter of the droplets is less than 1,000 μm, the coating efficiency will decrease, so by applying the droplets in a squall-like manner with a diameter of 1,000 or more, the coating efficiency on walls, etc. can be improved.

The present invention relates to a polymerization apparatus equipped with a scale inhibitor application device, and therefore, the scale inhibitor that can be used in this case may be any conventionally known scale inhibitor, including dyes, polar organic compounds, Any inorganic compound or polymer compound that has been proposed as having a scale prevention effect is included, and one or more of these compounds may be used by previously dissolving or dispersing them in an appropriate medium. As the medium, one or a mixed solvent of two or more of water, alcohol solvents, ester solvents, ketone solvents, hydrocarbon solvents, chlorinated hydrocarbon solvents, etc. is used.

Application may be performed using a pump, air pressure, nitrogen pressure, etc. The amount applied varies depending on the concentration of the scale inhibitor in the medium, but is generally 0.1
/m ² to 10/m ² , preferably 0.2 to 2/m 2
It should be ^m2 .

In this way, after the coating process has been completed on the inner surface of the condenser, the piping for each raw material, or the attachment port of the polymerization vessel connected to these, the aqueous medium is added to the polymerization vessel in the usual manner. Vinyl or diene monomers, a polymerization initiator, and other necessary additives such as monomer dispensing aids are charged and polymerized.

Specific examples of the above monomers include vinyl chloride, vinyl acetate, vinyl propionate, acrylic acid, methacrylic acid or their esters or salts, maleic acid or fumaric acid, and their esters or anhydrides, butadiene, chlorobrene, etc. , isobrene, styrene, acrylonitrile, vinylidene halide, vinyl ether, etc.

Furthermore, conventionally known dispersion aids, polymerization initiators, etc. are used to be added to the polymerization system.

Next, an experimental example in which polymerization was carried out using the apparatus of the present invention will be shown.

Experimental example 1 Acid black 14 was made into an aqueous solution of 0.1% by weight,
After adjusting the pH to 3.0 with phosphoric acid, 5% by weight of isobutyl alcohol was added to obtain a scale inhibitor coating solution.

A coating device is installed as shown in Fig. 1 on the condenser, each installation port, and the piping (total internal surface area 200m ² ) of the polymerization device, which has a stainless steel polymerization device with an internal volume of 130 m ³ . When the above scale inhibitor coating solution was sprayed from a conical nozzle (spray angle: 45°, spray rate: 40/min) at a pump pressure of 10 kg/cm ² at a rate of 0.5/m ² , the results were as follows.
The inner surface of the condenser, the inner surface of each installation port, and the inner surface of the piping were thoroughly coated.

Next, the following weight ratios were charged into a polymerization vessel (total amount charged: about 110 m ³ ), and polymerization was carried out at 57°C for 7 hours.

Vinyl chloride monomer 100 parts by weight Water 130 〃 Partially saponified polyvinyl alcohol 0.04 〃 Hydroxypropyl methylcellulose
0.02 〃 Di-2-ethylhexyl peroxydicarbonate 0.04 〃 The above polymerization operation was performed as one batch, and the same coating as above was applied for each batch, and the polymerization operation was repeated. Even after 600 batches, the inside of the condenser and each attachment remained. No scale was observed inside the mouth or pipes.

Experimental Example 2 A 0.1% by weight methanol solution of nigrosine black was used as a scale inhibitor coating solution.

A coating device is installed as shown in Fig. 1 on the condenser, each installation port, and piping (total internal surface area 6 m ² ) of the polymerization device, which has a stainless steel polymerization device with an internal volume of 1000 mm, and the nozzle of this coating device (full conical When the above scale inhibitor coating solution was sprayed from a nozzle (spray angle: 45°, spray rate: 45/min) at a nitrogen pressure of 10 Kg/m ² at a ratio of 1/m ² , it was applied to the inner surface of the condenser and each mounting hole. The inside surface of the pipe and the inside surface of the pipe were thoroughly coated.

Next, charge the following weight ratio into this polymerization vessel (total charge amount: approximately 900%) and further at 70℃ for 7 hours.
Polymerization was carried out at 80°C for 2 hours.

Styrene 70 parts by weight Acrylonitrile 30 〃 Water 120 〃 Hydroxyapatite 0.5 〃 Sodium lauryl sulfate 0.01 〃 Lauroyl peroxide 0.35 〃 The above polymerization operation was treated as one batch, and the same coating as above was applied for each batch, and the polymerization operation was repeated. Even after 30 batches, no scale was observed inside the condenser, each installation port, or inside the piping.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram of a polymerization apparatus in which a scale inhibitor coating device is installed on the condenser, each attachment port, and piping of the polymerization vessel, and FIG. 2 is a sectional view of the coating device. 1...Polymerizer, 2...Condenser, 3...Installation port, 4...Coating device, 5...Storage tank, 6
...Pump, 7...Piping, 8...Flange, 9...
…nozzle.

Claims (1)

[Claims] 1 Piping for raw materials for polymerization vessel, condenser,
Alternatively, a short pipe with the other end closed with a flange is installed at the installation port of these polymerization vessels, and an anti-scaling agent application device equipped with a pressure shower type spray nozzle or a drill hole nozzle is installed in the center of the flange. A polymerization device.