JPH0410883B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for polymerizing monomers such as vinyl chloride that suppresses scale adhesion during the polymerization process. In particular, it prevents foaming on the surface of the polymerization liquid and entrainment of product droplets, thereby improving the polymerization process. The purpose is to improve safety and significantly improve the operating rate of polymerization equipment. When monomers such as vinyl chloride are subjected to suspension or emulsion polymerization in a polymerization tank, a phenomenon of bubbling is observed on the liquid surface of the polymerization tank. It is known that in addition to making their operation difficult, they also cause various inconveniences such as scale adhesion to the walls of the polymerization tank. This bubbling phenomenon occurs when the monomers are suspended and charged into the polymerization tank together with emulsifiers and additives before the start of polymerization, and when the monomers are withdrawn and recovered during or at the end of polymerization, but this phenomenon is noticeable. Scale is formed on almost the entire inner wall of the gas phase of the polymerization tank, which makes it difficult to control the polymerization temperature, reduces the quality of the produced polymer, and even causes the escape of polymer particles entrained in bubbles. This will significantly reduce the operating rate. The present inventors have arrived at the present invention as a result of extensive research to solve these problems.
The method for polymerizing monomers such as vinyl chloride according to the present invention uses a horizontal dispersion plate equipped with a plurality of radially inclined blades around the upper gas phase region of a rotating shaft, and a stirring blade in the lower liquid phase region. When monomers such as vinyl chloride are subjected to suspension or emulsion polymerization in polymerization tanks having the same structure, water in an amount of 3% or more of the total charging volume is poured onto the horizontal dispersion plate from the start of polymerization to the end of polymerization. The feature is that polymerization is carried out while pouring water into the polymer. 1 to 4, which illustrate an apparatus for carrying out the method of the present invention, will be described in detail below. The example of the apparatus shown in FIG. 1 is a case where a 1.5 autoclave is used as a polymerization tank. Reference numeral 1 denotes a rotating shaft, and a stirring blade 2 is attached to the lower liquid phase region. The rotating shaft 1 passes through the lid 3 of the autoclave and is adapted to rotate in the direction of the arrow by suitable driving means. A horizontal dispersion plate 4 is fixed by a boss 5 in the upper gas phase region of the rotary shaft 1 near the lid 3, and around the dispersion plate 4 four circular blades 6 are arranged at an angle of approximately 30° with respect to the horizontal plane. attached at the corner. As a means for injecting water onto the distribution plate 4, a water supply pipe 7 that penetrates the lid 3 and is set on the distribution plate is used. Water in an amount of 3% or more of the total charging volume is supplied to this water supply pipe from a water injection pump (not shown) communicating with the pot 8 of the lid 3 from the start of polymerization to the end of polymerization. The water poured onto the dispersion plate 4 is uniformly distributed and supplied to each blade by the rotation of the rotating shaft 1, and the water is uniformly scattered from each blade to the wall surface of the gas phase section by centrifugal force. The water that has reached the wall surface forms a wet surface on the wall surface, cleans the gas phase portion and the gas-liquid interface, and can prevent and remove scale adhesion. In this case, the autoclave tank diameter is 105mmφ.
The diameter of the dispersion plate with blades is 50mmφ, and the number of rotations is 700 times/
It was hot in minutes. FIG. 2 exemplifies the case where a 1 m ³ autoclave is used as the polymerization tank. A flat blade stirring blade 2 is installed in the liquid phase portion of the rotating shaft 1.
is attached, and the horizontal dispersion plate 4 is fixed at a high position in the gas phase section by a boss 5, which is the same as in the case of Fig. 1, but the 8 plates attached to the horizontal dispersion plate 4 are The blade 6 is rectangular and is inclined at 30 degrees with respect to the horizontal plane 4 as shown in FIG. Different. Although any known water supply means may be used, it is necessary to set the water supply pipe 7 so that water can be poured onto the distribution panel. In this case, the autoclave tank diameter is 850mmφ.
The diameter of the bladed dispersion plate was 500 mmφ, the width of the rectangular blade was 60 mm, and the rotation speed was 160 times/min. In this example as well, when water is poured onto the horizontal dispersion plate as in the previous example, the water is uniformly scattered onto the wall surface of the gas phase section.
It can wash away foaming and completely prevent product entrainment. FIG. 4 shows another embodiment of the horizontal dispersion plate used in the method of the present invention, in which inclined blades 11 are arranged around the horizontal dispersion plate 4 to which the rotating shaft 1 is fixed by the boss 5 in a chevron shape (∧ This exemplifies the case in which the scales are connected to each other (shape), and the same scale adhesion prevention and removal effects as described above can also be obtained. Next, the details of the present invention will be explained with reference to examples. Example 1 (Suspension polymerization of vinyl chloride) 200 kg of vinyl chloride monomer and 75 g of diisopropyl peroxydicarbonate were placed in a 1000 stainless steel polymerization tank as shown in Figure 2, which was equipped with an agitator with a 400 mm paddle blade inside. , 250 g of partially saponified polyvinyl alcohol and 25 g of hydroxypropyl methylcellulose were charged, and 0, 3, 5, 10, and 15% water was continuously supplied from the start of polymerization to the end of polymerization based on the total charge volume on a horizontal dispersion plate. While stirring at a stirring speed of 200 times/min, the internal temperature was 57℃.
Polymerization was repeated for 12 hours, and the prevention of scale adhesion by the inclined blades at the gas-liquid interface and the gas phase and the entrainment of product droplets due to monomer recovery at the end of polymerization were investigated, and the results shown in Table 1 were obtained. .

[Table] Example 2 (Suspension polymerization of styrene) Styrene monomer 180% was added to the same polymerization tank as in Example 1.
Kg, acrylonitrile 120Kg, water 300Kg, hydroxyapatite 6Kg, sodium lauryl sulfate 120Kg
900 g of t-butyldodecyl mercaptan and 1.2 kg of lauroyl peroxide were charged into a horizontal dispersion plate, and 0, 3, 5, 10, 15% of water was added to the total volume from the start of polymerization until the end of polymerization, or during polymerization. The mixture was continuously fed until the polymerization was completed, and the internal temperature was kept at 70°C for 3 hours while stirring at a stirring rate of 150 times/min, and then the temperature was raised from 70° to 80°C over 2 hours.
Then, polymerization was repeated at 80°C for 1 hour, and the same scale prevention effect as in Example 1 was investigated.
The results shown in Table 2 were obtained.

[Table] Example 3 (Emulsion polymerization of ABS) In the same polymerization tank as in Example 1, 180 kg of polybutadiene latex (solid content 50%) and 300 kg of styrene monomer were added.
Kg, acrylonitrile 120Kg, t-dodecylmercaptan 600Kg, potassium oleate 3Kg, and potassium persulfate 3Kg were charged, and 0, 3, 5, 10, 15% of water based on the total charge volume was added onto the horizontal dispersion plate from the start of polymerization. Supply until the end of polymerization, stirring speed 150
Polymerization was repeated for 10 hours at an internal temperature of 50° C. while stirring at a rate of 50° C., and the scale prevention effect was similarly investigated, and the results shown in Table 3 were obtained.

[Table] As is clear from the above examples, according to the method of the present invention, the water injected onto the horizontal dispersion plate is uniformly scattered from the inclined blades, forming a gas phase and a gas-liquid phase on the wall surface of the polymerization tank. Since the interface is cleaned, there is no scale attached to the polymerization tank, and scale is also removed, so the operating rate of the polymerization process can be greatly improved.

[Brief explanation of drawings]

FIG. 1 is a partial explanatory diagram showing an example of an apparatus for carrying out the method of the present invention, FIGS. 2 and 4 are partial explanatory diagrams showing other embodiments, and FIG. 3 is a partial enlargement of FIG. 2. It is a diagram. 1...Rotating shaft, 2...Agitation blade, 3...Lid, 4...Horizontal distribution plate, 5...Boss, 6...Blade, 7...Water supply pipe, 8...Kotoku, 9...Backing plate, 10...Groove, 11...
Slanted vane.

Claims (1)

[Claims] 1. Polymerization of monomers such as vinyl chloride is carried out in a polymerization tank that has a horizontal dispersion plate surrounded by multiple radial inclined blades in the upper gas phase region of the rotating shaft, and stirring blades in the lower liquid phase region. When carrying out suspension or emulsion polymerization of polymers, the polymerization is carried out while pouring water in an amount of 3% or more of the total charging volume onto the horizontal dispersion plate from the start of polymerization to the end of polymerization. Polymerization method of monomers such as