JPS5883003A - Continuous bulk polymerization of thermoplastic resin - Google Patents

Abstract

PURPOSE:To allow a polymerization reaction to proceed under predetermined temperature conditions throughout the reaction to thereby obtain a good-quality thermoplastic resin, by controlling the amount of monomer to be sprayed according to the temperature of the polymerization solution, dividing the monomer into particles and uniformly spraying the monomer particles on the free surface of the polymerization solution which is being polymerized. CONSTITUTION:The temperature of a polymerization solution which is polymerized in a polymerizer 10 while part of the heat generated by the reaction solution is being removed by internal evaporation of monomer and cooling by a cooling medium is detected by a temperature detector 33 and inputted into a controller 34. The temperature of the polymerization solution detected in the controller 34 is compared with the target temperature of the polymerization solution for further operation. When there is a difference, the opening of an electromagnetic valve 31 is automatically controlled by this difference, whereby the amount of monomer to be sprayed is controlled. The monomer, after this control of amount, passes through a monomer spray nozzle 20 to a spray nozzle 32, where it is divided into particles which are then sprayed and uniformly distributed on the free surface of the polymerization solution which is being polymerized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a continuous polymerization method for thermoplastic resins, and in particular, a continuous bulk polymerization method for thermoplastic am suitable for continuously producing polystyrene resins by bulk polymerization method. It is related to.

Generally speaking, the higher the average molecular weight of polystyrene resin, the higher the average molecular weight.
In addition, it has a narrow molecular weight distribution, and has excellent mechanical properties such as tensile strength and impact resistance, as well as transparency and processability. On the other hand, since the degree of polymerization is determined only by the temperature of the polymerization solution, in order to obtain a high-quality product, it is desirable to carry out the polymerization at a constant temperature as much as possible, and temperature control becomes an overlapping issue.

Therefore, it is necessary to remove the polymerization reaction heat generated during the polymerization reaction. However, in polystyrene-based resins, as the polymerization reaction progresses, the viscosity of the polymerization solution during the polymerization reaction gradually increases, resulting in a decrease in the heat transfer coefficient and making it difficult to remove the heat of the polymerization reaction.

Therefore, in the conventional continuous bulk polymerization technology of polystyrene resins, great effort has been devoted to how to remove this polymerization reaction heat.

A typical example of a conventional continuous bulk polymerization method for thermoplastic resins will be explained with reference to FIG.

FIG. 1 is an explanatory diagram showing an example of the polymerization process of polystyrene resin used in the continuous bulk polymerization method of thermoplastic resin disclosed in Japanese Patent Application No. 141348/1982. The intermediate polymerization liquid of the resin) is introduced into the polymerization machine 10 through an inlet nozzle 11 provided on one side of the longitudinal direction of the horizontal continuous polymerization machine (hereinafter referred to as the polymerization machine) W, and is rotated within the polymerization machine 10. Stirring blade 13 accompanying rotation of axis
The polymerization reaction proceeds while being thoroughly stirred and mixed and cooled by the refrigerant introduced from the refrigerant inlet nozzle 14, flowing through the jacket rattle, and discharged from the refrigerant outlet nozzle 16. At this time, the pressure inside the polymerization machine 10 is adjusted using a pressure regulating valve so that the boiling point of the polymerization solution matches the target temperature of the polymerization solution. In this way, internal evaporation of monomers occurs in the polymerization solution, and the temperature of the polymerization solution does not rise above the boiling point of the polymerization solution and is kept constant. In actual operation, this operation can be easily realized by detecting the temperature of the polymerization liquid and automatically adjusting the pressure regulating valve (9) according to the deviation from the target temperature of the polymerization liquid. However, if the temperature of the polymerization solution is adjusted (by internal evaporation of monomers and cooling with a refrigerant), the boiling point of the polymerization solution increases as the polymerization reaction progresses, so A temperature distribution is generated in the direction (from left to right in FIG. 1). Furthermore, when the polymerization rate is relatively low, sufficient internal evaporation of the monomer occurs to easily remove the polymerization reaction heat and stirring heat, but in the region where the polymerization rate is high, the stirring heat increases as the viscosity increases. In addition to this, the amount of internal evaporation of the monomer decreases due to the decrease in the absolute amount of monomer in the polymerization solution, and the amount of heat generated cannot be sufficiently removed only by internal evaporation of the monomer and cooling with a refrigerant. I can't bear it anymore. Therefore, a controlled amount of monomer is directly sprayed onto the free surface of the polymerization liquid inside the polymerizer 10 from the outside through the monomer spray ports 4 which are divided into a plurality of parts in the longitudinal direction of the polymerizer 10. do. When this dispersed monomer (hereinafter abbreviated as the dispersed monomer) comes into contact with the free surface of the polymerization liquid, it immediately reaches the boiling point of the dispersed monomer and evaporates, absorbing the latent heat of vaporization from the polymerization liquid and increasing the temperature of the polymerization liquid. Removes the amount of heat generated. In this way, the temperature of the polymerization liquid is adjusted (by internal evaporation of the monomer, cooling by the refrigerant, and evaporation of the sprayed monomer), and the polymerization reaction of the polymerization liquid progresses. Polymerization machine 10
The evaporated matter extracted outside and evaporated during the progress of the polymerization reaction is discharged to the outside of the polymerization machine 10 from the evaporated matter extraction nozzle.

In this continuous bulk polymerization method for thermoplastic resins, the monomer is only sprayed from the monomer spraying port in a limited narrow area directly below the monomer spraying port, and the polymerization liquid is Since the thermoplastic resin is not evenly distributed over the free surface of the resin, the temperature of the polymerization solution cannot be adjusted sufficiently, and therefore, a high-quality thermoplastic resin cannot be obtained.

The purpose of the present invention is to eliminate the above-mentioned drawbacks.The present invention adjusts the amount of monomer sprayed according to the temperature of the polymerization liquid during the polymerization reaction in the polymerization machine, and converts the scissors monomer into particles to cause the polymerization reaction. Continuous lumps of thermoplastic resin that can be uniformly distributed over the free surface of the polymerization solution in progress to allow the polymerization reaction to proceed under specified temperature conditions and to obtain a high-quality thermoplastic resin. It provides a polymerization method.

An embodiment of the present invention will be explained with reference to FIGS. 2 and 3.

FIG. 2 is an explanatory diagram showing an example of a polystyrene-based tree polymerization process according to the present invention, in which the same parts of the apparatus as in FIG.

In Figure 2, the amount of monomer sprayed is adjusted on the downstream side of the monomer spraying nozzle ■ which is divided into a plurality of units in the longitudinal direction of the polymerizer 1O and protruded inside the polymerizer 1G. For example, three solenoid valves are provided, and a spray nozzle is attached to the end of the monomer dispersion nozzle.
A temperature detector blade for detecting the temperature of the polymerization liquid in progress of the polymerization reaction is provided at a position substantially facing the spray nozzle n in the longitudinal direction, and the temperature detector and the solenoid valve 31 detect Each of the three stain magnetic valves is connected to a control device that automatically controls the opening degrees of the three stain magnetic valves depending on the deviation between the temperature of the polymerized liquid and the target temperature of the polymerized liquid.

In the polymerization machine 1G, a temperature sensor detects the temperature of the polymerization solution in which the polymerization reaction progresses while a part of the generated heat of the polymerization solution is removed by internal evaporation of monomers and cooling with a refrigerant.
34. The control device compares and calculates the detected temperature of the polymerization liquid and the target temperature of the polymerization liquid, and if a deviation occurs, the valve opening degree aimed at the stain solenoid valve is automatically controlled based on this deviation. Spread amount is adjusted. The monomer, whose spray amount has been adjusted, passes through the monomer spray nozzle and reaches the spray nozzle, where it is made into particles and is uniformly spread over the free surface of the polymerization liquid during the polymerization reaction, as shown in Figure 3. It is distributed so that the When this particulate and dispersed monomer (hereinafter abbreviated as particulate dispersed monomer) comes into contact with the free surface of the polymerization liquid, it immediately reaches the boiling point of the particulate and dispersed monomer and evaporates from the polymerization liquid. Removes the latent heat of vaporization and removes the amount of heat generated from the polymerization liquid. In this way, the temperature of the polymerization solution is adjusted by internal evaporation of the mono-heptamer, cooling by the refrigerant, and particle dispersion.The temperature of the polymerization solution is regulated by the evaporation of the monomer, and the polymerization reaction of the polymerization solution proceeds.

In order to remove the amount of heat generated from the polymerization liquid by the particulate dispersed monomer in a sufficient manner, it is necessary to appropriately adjust the particle diameter of the particulate dispersed monomer using the spray nozzle depth. The lower limit of the particle size of the particulate dispersed monomer depends on the distance from the spray nozzle n to the free surface of the polymerization liquid, that is, the reach distance, and the upper limit depends on:
The ratio of the dispersion area of the particulate dispersed monomer to the amount of monomer dispersion per unit time, that is, the required dispersion area, is determined respectively. For example, in the case of reach distance -Zoom, the lower limit of the particle size of the particulate dispersion monomer is 0.1M, and below that, the ratio of the particle volume to this surface area of the particulate dispersion monomer is large, The particulate dispersed monomer injected from the spray nozzle evaporates before reaching the free surface of the polymerization liquid. In addition, when the required dispersion area = 0°33h/■, the upper limit of the particle diameter of the particulate dispersed monomer is 2M, and if it is larger than that, the required dispersion area cannot be secured and the particulate dispersed monomer is not added to the polymerization liquid. Uneven distribution over the free surface becomes impossible.

As in this example, the amount of monomer sprayed is adjusted according to the temperature of the polymerization liquid during the polymerization reaction in the polymerization machine, and the monomer is pulverized by a spray nozzle) and the monomer is dispersed into particles as the polymerization reaction progresses. If it is uniformly distributed over the free surface of the polymerization solution in the polymerization reaction, the temperature of the polymerization solution during the polymerization reaction can be maintained at the target temperature at all times during the progress of the polymerization reaction.

As explained above, the present invention is a method for continuous bulk polymerization of a thermoplastic resin using a horizontal continuous polymerization machine and adjusting the pressure inside the continuous polymerization machine to a predetermined pressure while the polymerization reaction is in progress. Continuous bulk polymerization of thermoplastic resin in which the amount of monomer sprayed is adjusted according to the temperature of the polymerization solution, and the monomer is granulated and uniformly sprayed on the free surface of the polymerization solution during the polymerization reaction. Since it is legal, the temperature of the polymerization solution can always be maintained at the target temperature during the progress of the polymerization reaction, and mechanical properties such as tensile strength and impact resistance, transparency, and processability are maintained. It has the effect of producing excellent, high-quality thermoplastic resin.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram illustrating a conventional continuous bulk polymerization method for thermoplastic resins, and an explanatory diagram showing an example of a polymerization process for polyethylene resins. FIGS. Fig. 2 is an explanatory diagram showing an example of the polymerization process of polyethylene resin according to the present invention, and Fig. 3 shows the free surface of the polymerized liquid of the monomer particles dispersed by a spray nozzle. It is an explanatory view showing the dispersion situation to. 1G... Polymerization machine, 11... Inlet nozzle, Minoru... Rotating shaft, ■... Stirring blade, 14
...Refrigerant inlet nozzle, Takumi...jacket,
16... Refrigerant outlet nozzle, 17... Extraction screw, 18... Outlet nozzle, 19.
... Evaporated matter outlet nozzle, (9) ... Monomer dispersion nozzle, Addition ... ... Pressure adjustment valve, 31 ...
... Solenoid valve, ... Spray nozzle, ...
・・Temperature detector, idiom ・・・Control device = J-1 fig. 2 fig. 1”1 'J/-3 sub

Claims (1)

[Claims] 1. A rotating shaft with a stirring blade supported inside the cylindrical body is provided, an inlet for the polymerization liquid to be polymerized is provided on one longitudinal side of the front body, and an inlet for the polymerization liquid to be polymerized is provided on the other side in the longitudinal direction. In a method in which continuous bulk polymerization of nine thermoplastic resins is carried out by adjusting the pressure inside the scissors transverse wave continuous polymerization machine to a predetermined value using a Yokotaki continuous polymerization machine equipped with an extraction device and an outlet, the polymerization liquid during the polymerization reaction is The thermoplastic resin is characterized in that the amount of monomer sprayed is adjusted according to the temperature of the thermoplastic resin, and the wrinkled monomer is made into particles and sprayed evenly over the free surface of the polymerization liquid during the polymerization reaction. Continuous bulk polymerization method.