JPH0147481B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polymerization apparatus having a scale inhibitor coating device incorporated in the polymerization vessel.

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, reducing the quality of the product. On the other hand, it takes excessive effort and time to remove this scale. Not only that, but unreacted monomers are adsorbed in this scale, so 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 a disadvantage.

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 less and then applied.

However, as specific means for carrying out these coating methods, there are methods such as filling a polymerization vessel with the coating liquid and then drawing it out, and spraying the coating liquid. The method of filling the vessel to capacity has the disadvantage that residual polymers or water in the polymerization vessel are mixed into the filled coating solution, making it impossible to use it repeatedly. On the other hand, the spray coating method has the advantage that the coating solution is not contaminated by residual polymers or water, so the coating solution can be constantly applied according to the prescription, and there is no waste. has.

However, this spray application is carried out from a manhole or the like of the polymerization vessel. Therefore, in today's world where the risk of injury to the human body caused by monomers has become a serious issue, opening manholes poses many problems, and there is a strong demand for operation in a closed system, or at least an automatic coating method.

Moreover, this scale build-up occurs not only inside the polymerization vessel, but also in condensers where gaseous monomers come into contact.
It also occurs in equipment such as pipes for charging raw materials and installation ports in these polymerization vessels. It was not easy to apply the anti-scaling agent to these areas, and there were problems such as the need to remove the equipment.

In order to satisfy these demands, the present invention has developed a polymerization device incorporating a coating device that can automatically and uniformly apply a scale preventive agent to the inner walls of the polymerization vessel and the stirring device, etc., as a result of intensive research. This is equipped with a coating device consisting of a scale preventive agent dispersion pipe with multiple nozzle ports facing in multiple directions, in order to apply the scale preventive agent to the entire inner wall of the polymerization vessel, in the upper part of the polymerization vessel equipped with a stirrer. The present invention relates to a polymerization device consisting of:

According to the present invention, the scale preventive agent can be applied uniformly without leaving any uncoated area, and the coating time is automatically applied within a few seconds to several tens of seconds. Therefore, the operation of applying the scale preventive agent every polymerization batch or every few batches can be carried out very easily and safely, and the desired excellent scale preventive effect can be obtained.

The present invention will be explained in detail below.

The coating device of the present invention, which has a nozzle for applying a scale preventive agent installed in the upper part of the polymerization vessel, performs polymerization by supplying the scale preventive agent (liquid) to this coating device from outside the polymerization vessel using a pump or the like. A coating film of anti-scaling agent is formed on the inner wall of the vessel and the surface of the stirring shaft. FIG. 1 shows an outline of this system, in which 1 is a polymerization vessel, 2 is a coating device installed in the upper part of the polymerization vessel 1, 3 is a scale inhibitor storage tank, 4 is a pump, and 5 is piping.

FIG. 2a is a schematic plan view showing one embodiment of the coating device, and FIG. 2b is a schematic side view showing the installation position of the coating device. In the figure, 2-1 is a coating device with an annular structure, and the anti-scaling agent pumped by a pump is supplied to the coating device from a pipe 5, and a nozzle port 6.
As a result, the scale preventive agent is applied to the entire inner wall of the polymerization vessel, the surface of the stirrer, etc. Although FIG. 2a shows a coating device having an annular structure, the coating device may have a circular shape, an oval shape, a polygonal shape, or the like.

The coating device 2-1 is provided with a large number of nozzle ports 6, and these nozzle ports are located in many directions as shown in FIG. 3 (partially enlarged view).

Figure 4 shows a coating device that allows the scale preventive agent to be applied well to the barrier plate and the inner wall of the polymerization vessel near the barrier plate when a barrier plate is provided on the side of the polymerization vessel. FIG. 3A is a schematic plan view of the same, and FIG. 2B is a schematic side view showing the positional relationship between the coating device and the jammer plate in the polymerization vessel. This coating device 2-2 consists of a combination of an annular coating device 2-1 and a branched coating device 7 as shown in FIG. The plate 9 and the inner wall surface of the polymerization vessel near the plate 9 are provided in a direction in which the scale inhibitor can be well applied.

The coating device 2-3 shown in FIG.
It consists of a structure in which four branched coating devices 11 are installed at the base of the present invention, and FIG.

Note that the support frame 10 may be either an annular body having a nozzle opening as shown in the drawings or a simple annular body having no nozzle opening or the like. In addition, in some cases, as shown in Figure 6, 4
It may be of a structure in which book branch applicators are connected in a cross pattern, or it may be of a structure in which the branch applicator attached to a support frame rotates as shown in FIG. The coating device 2-4 shown in FIG. 8a has a structure in which branched coating devices are combined in the shape of a television antenna, and FIG. 8b is a schematic side view thereof.

The type of nozzle for ejecting the scale preventive agent provided in each application device may be either a pressure shower type spray nozzle or a drilled hole. Examples of the pressure shower type spray nozzle include a fan-shaped nozzle, a descaler nozzle, a full conical nozzle, Empty conical nozzles, straight nozzles, tank drum cleaning nozzles, etc. are used.

The diameter of droplets ejected from the nozzle is preferably 1000μ or more. If the diameter of these droplets is less than 1000 μm, the coating efficiency will decrease, so this droplet size is less than 1000 μm.
By applying the above coating in a squall manner, it is possible to improve the coating efficiency on a wall surface or the like.

The present invention relates to a polymerization apparatus equipped with a coating device having a nozzle for applying a scale inhibitor, and therefore, any conventionally known scale inhibitor may be used as the scale inhibitor that can be used in this case.
This includes dyes, polar organic compounds, inorganic compounds, and polymeric compounds that have been proposed to exhibit scale prevention effects, and one or more of these substances must be dissolved or dispersed in an appropriate medium in advance. Let it be used. 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 carried out using a pump, air pressure, nitrogen pressure, etc., and the amount sprayed from the nozzle varies depending on the concentration of the scale inhibitor in the medium, but is generally 0.1/m ² to 10/m ² , preferably. teeth
It may be 0.2 to ² /m2.

After coating the inner walls of the polymerization vessel and other areas that come into contact with the monomers in this manner, the water medium, vinyl or diene monomer, and polymerization initiator are added to the polymerization vessel in a conventional manner. , and other necessary additives such as monomer dispersion 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, chloroprene. , isoprene, styrene, acrylonitrile, vinylidene halide, vinyl ether, etc.

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

Note that there is a risk that the nozzle opening of the applicator may become clogged during polymerization, so to prevent this clogging, as shown in FIG. It is preferable to use a means of discharging water little by little. That is, in the figure, water is supplied by a pump 12 to the coating device 2 via a valve 14 (valve 13 is closed).

It is desirable that this water injection starts when the polymerization raw materials are charged and is continued continuously until the polymerization slurry is taken out after the polymerization period. It goes without saying that the amount of water injected must be determined by considering the amount of polymerization charge and the volume of the space in the polymerization vessel, but in a general industrial-scale polymerization vessel, the amount of water injected is approximately 0.01.
/ minute to 10/minute.

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.

Stainless steel polymerization vessel with an internal volume of ^130m3 (inner surface area
The coating device shown in Fig. 4 was installed in the upper part of the 150 m ² ) area, and the above scale inhibitor coating solution 100 was sprayed at a pump pressure of 10 kg/cm ² from a nozzle with a drilled hole of 1.5 mm in diameter. The inner surface of the container was coated evenly and thoroughly. At the same time, the entire surface of the stirrer and jammer board was coated. After this application, the jacket temperature was raised to 90°C and dried for 10 minutes.

Next, after washing the inside of the polymerization vessel with water, the following weight ratios were charged (total amount of charged approximately 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 methyl cellulose 0.02 〃 Di-2-ethylhexyl peroxydicarbonate 0.04 parts by weight When the polymerization contents were taken out after the reaction was completed and the inside of the polymerization vessel was washed with water, scale was found. No adhesion was observed.

Further, in the above, after applying the coating solution and drying and rinsing with water, water was supplied to the coating device at a rate of 2/min as shown in FIG. 9, and the same polymerization operation was carried out while injecting water from the nozzle port. This polymerization operation is considered as one batch,
When the polymerization was repeated 600 times, no clogging of the nozzle was observed.

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

The coating device shown in Fig. 2 was installed in the upper part of a stainless steel polymerization vessel with an internal volume of 1000 mm (inner surface area: 4 m ² ), and the above-mentioned scale inhibitor coating liquid 2 was applied from the coating nozzle.
When applied by spraying it at a nitrogen pressure of 10 kg/cm ² , the inner surface of the polymerization vessel was coated uniformly. After this coating, the jacket temperature was raised to 50°C and dried for 10 minutes.

After washing the inside of the polymerization vessel with water, pour water from the nozzle of the coating device.
The operation of pouring water into the polymerization vessel at a rate of 0.04/min was started.

Next, the following polymerization ratio was charged into this polymerization vessel (total amount charged: about 900%), and polymerization was carried out at 70°C for 7 hours and further 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 After the reaction, the polymerization contents were taken out and the inside of the polymerization vessel was washed with water, but no scale was observed.

When the above operation was performed in one batch and polymerization was repeated, no clogging of the nozzle was observed even after 30 batches.

[Brief explanation of drawings]

Fig. 1 is a schematic explanatory diagram showing a coating device having a nozzle for applying a scale inhibitor installed in the upper part of the polymerization vessel;
Figures 2a and b are schematic explanatory diagrams showing one aspect of the coating device, Figure 3 is a partially enlarged view showing the installation state of the nozzle opening, Figures 4a and b, Figures 5a and b, and Figure 6. , 7th
The figure and FIGS. 8a and 8b each illustrate another embodiment of the coating device. FIG. 9 shows a configuration of the polymerization apparatus shown in FIG. 1 in which water can be supplied to the coating device. DESCRIPTION OF SYMBOLS 1...Polymerizer, 2...Coating device, 3...Storage tank, 4...Pump, 5...Piping, 6...Nozzle port, 7...Branch coating device, 10...Support frame, 1
1... Branch coating device, 12... Pump, 13,
14...Valve.

Claims (1)

[Claims] 1. At the top of the polymerization vessel equipped with a stirrer, a coating device consisting of a scale preventive agent dispersion pipe having a large number of nozzle ports facing in multiple directions is installed to apply the scale preventive agent to the entire inner wall of the polymerization vessel. A polymerization device.