JPS6028407A - Production of styrene resin having high strength and polymerization apparatus therefor - Google Patents

Abstract

PURPOSE:To obtain the titled polymer having high relative viscosity and excellent strength, by polymerizing styrene in a complete-mixing stirring polymerizer under specific condition, continuing the polymerization in a successive plural stirring polymerizers, introducing the polymer in a tubular polymerizer containing a static mixer, and carrying out the adiabatic polymerization under specific condition. CONSTITUTION:A styrene resin is produced continuously by bulk or solution polymerization as follows. Styrene monomer is polymerized in the complete-mixing stirring polymerizer 2 at a polymerization temperature of 100-130 deg.C to a monomer conversion of 30-60% to obtain a polymer having a relative viscosity of 2.40-3.00. The polymer liquid is introduced in one or successive two or more stirring polymerizers 4, 5 and polymerized at 100-150 deg.C until the monomer conversion reaches 55-75% to obtain a polymer having a relative viscosity of 2.50-3.00. The polymer liquid is introduced into the tubular reactor 6 containing a static mixer, and polymerized adiabatically at <=185 deg.C keeping the monomer conversion at the outlet of the tubular polymerizer 6 to <=90%. The objective resin having a relative viscosity of >=2.30 can be produced by this process.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a styrenic resin with excellent strength. More specifically, the present invention relates to a method for continuously producing a styrenic resin having excellent strength by bulk or solution polymerization.

It is widely known that styrenic resins are produced by continuous bulk polymerization, continuous solution polymerization, or suspension polymerization. However, it is difficult to manufacture high-strength styrenic resin, which has a comparatively weak brittle fracture strength by continuous bulk polymerization or continuous solution polymerization, by increasing the molecular weight of the styrenic resin. This is extremely difficult due to the extremely high viscosity of the polymerization solution, and it has not been possible to produce it under industrially advantageous conditions. Therefore, production of styrenic resins with excellent strength, typified by falling weight strength, has been carried out exclusively by suspension polymerization. For some reason, in the suspension polymerization method, the stirring power of the polymerization tank is hardly affected by the viscosity of the polymerization liquid itself because the polymerization liquid is dispersed in water, and is due to the stirring of high viscosity liquid. This is because it does not cause any problems.

For example, in Japanese Patent Publication No. 47-39234, there are a plurality of prepolymerization zones, stirring reflux zones in which heat is removed by evaporation of monomer or hydrocarbon diluent, and finishing zones in which polymerization continues under substantially adiabatic plug flow conditions. A continuous process for producing polyvinyl-aromatic compounds is provided in which bulk polymerization is carried out in separate polymerization zones.

However, according to the example, the reaction temperature in the stirring reflux zone, which is the main reactor, is 173°C, which is much higher than that of the present invention, and the effect of this temperature lowers the viscosity and makes stirring possible. According to this method, the molecular weight of the polymer produced is of course relatively small because the polymerization is carried out at high temperatures. Therefore, with this method, it is not possible to improve the strength of the polymer by increasing the molecular weight of the polymer as in the present invention. In addition, the finishing reactor performs polymerization under adiabatic plugged flow, and according to the examples, the temperature is 207°C, which is much higher than the temperature of the tubular polymerization vessel described later in the present invention. Therefore,
Naturally, the amount of low molecular weight products produced will increase, and the molecular weight distribution will therefore become wider. Therefore, it is not possible to control the molecular weight distribution of the produced polymer to improve its strength as in the present invention.

The present invention enables the production of high-strength styrenic resins using high molecular weight polymers, which was conventionally only possible through suspension polymerization, by combining a plurality of stirring polymerization tanks and tubular polymerization vessels, and their polymerization rates and polymerization temperatures. By specifying the conditions, it is possible to keep the stirring power in the polymerization vessel within an industrially practicable range to produce a high molecular weight polymer. This made it possible to manufacture styrene resin.

That is, the method for producing a styrenic resin of the present invention is a method for continuously producing a styrenic resin by bulk or solution polymerization, in which monomers are first prepared in a completely mixed stirred polymerization tank at a polymerization temperature in the range of 100 to 130°C. Polymerize until the conversion rate is 30-60% and the relative viscosity is 2.4.
The polymerization solution is then introduced into one or two or more continuous stirring polymerization tanks, where the monomer conversion rate is 55 to 75 at a polymerization temperature of 100 to 150°C. Polymerize until the relative viscosity is 2.5%.
0 to 3.00 is produced, and then the polymerization solution is introduced into a tubular polymerization vessel equipped with a static mixer, where it is adiabatically heated at a polymerization temperature of 185°C or less at the outlet of the tubular polymerization vessel. It is characterized in that it is polymerized to such an extent that the monomer conversion rate does not exceed 90% to produce a polymer having a relative viscosity of 2.30 or more.

Furthermore, the present invention provides a polymerization apparatus for use in this manufacturing method.

It consists of at least two continuous stirring polymerization tanks connected to a tubular polymerization vessel, and the first stirring polymerization tank is a vertical complete mixing type stirring system that mainly removes heat by jacket heat transfer and/or boiling point reflux. The stirred polymerization tank and other stirred polymerization tanks are substantially liquid-filled tanks in which reaction heat is substantially removed by a jacket or coil, and the tubular polymerization tank is a static mixer. This is a continuous polymerization device for styrene resin, which is characterized by having a built-in bowl and jacket.

The relative viscosity as used in the present invention refers to a solution in which a polymer component in a polymer solution or resin is dissolved in toluene at a concentration of 1%.
Values measured with a viscosity tube at °C.

The styrenic resin used in the present invention refers to a homopolymer of styrene, a nuclear-substituted styrene such as para-methylstyrene, terjarifthylstyrene, and an α-substituted styrene such as α-methylstyrene, or a homopolymer thereof. Copolymers of several of these, or copolymers of one or several of these and esters of acrylic acid or methacrylic acid such as acrylonitrile and methyl methacrylate, and styrenic compounds such as maleic anhydride. It is a copolymer with one type of monomer copolymerizable with the monomer or with several types of these monomers.

The method of the present invention uses a polymerization device that combines a plurality of continuous stirring polymerization tanks and a tubular polymerization vessel, but the first polymerization tank (hereinafter referred to as the first tank) must be of a complete mixing type, The number of stirring polymerization tanks may be two or three or more, but increasing the number too much is not preferable due to the economical problem of increased construction cost.

In the first tank, the monomer conversion is maintained between 30 and 6 degrees, more preferably between 40 and 55 degrees. Further, the polymerization temperature of the first tank is preferably 100°C to 130°C. u11
It is maintained at a specific temperature between 0'C-125C. In addition, the first tank is a so-called complete mixing type vertical polymerization tank, and the heat removal method for polymerization heat is usually carried out by boiling point reflux method, heat transfer by jacket or coil, or sensible heat utilization of raw monomer liquid. Any of the above methods or a combination thereof may be used, but it is preferable that the above-mentioned predetermined temperature be maintained substantially uniformly.

If the polymerization temperature is set higher than 130°C, a low molecular weight polymer will be produced, making it impossible to obtain a high molecular weight resin. It is generally known that in polymerization reactions, it is easier to produce high molecular weight polymers at lower polymerization temperatures, but it is not possible to obtain a sufficient polymerization rate when the polymerization temperature is lower than 100°C. do not have. In addition, the conversion rate of monomer in the first tank was increased to 30%.
, preferably 40 or more, in order to efficiently obtain a high molecular weight polymer.

Further, unless the conversion rate in the first tank is set to 60 degrees or less, preferably 55 degrees or less, the consumption of stirring power becomes enormous, making it difficult to implement on an industrial scale.

By obtaining a high molecular weight polymer with a relative viscosity of 2.40 to 3.00 in the first tank, the relative viscosity of the final resin obtained is 2.30 or more, and the molecular weight distribution is good. This makes it possible to maintain the range.

When the stirred polymerization tank group consists of two stirred tanks, the polymerization liquid continuously sent out from the first tank is transferred to the second polymerization tank (
(hereinafter referred to as the second tank), the monomer conversion rate is 55% to 7.
It is polymerized to a conversion of 5%, more preferably between 60% and 70%. In addition, the polymerization temperature in the second tank is 100°C to 1°C.
The temperature is maintained at 50°C, preferably between 110°C and 130°C. The second tank may be a stirred tank that is substantially full of liquid and in which the reaction heat is substantially removed by heat transfer through a jacket or coil, but the polymerization temperature is set at 150°C.
If the temperature is too high, a low molecular weight polymer will be produced, making it impossible to obtain a high molecular weight resin. Furthermore, if the polymerization temperature is low, a sufficient polymerization rate cannot be obtained. Furthermore, it has been found that increasing the monomer conversion rate higher than 150°C is practically impracticable because the consumption of stirring power becomes enormous.

Further, in the present invention, when the stirred polymerization tank group consists of three or more stirred tanks, the monomer conversion rate of the second tank is preferably 70 or less, more preferably 60 or less, and the polymerization temperature is 100 or less. C. to 14'0 DEG C., preferably 110 DEG C. to 130 DEG C., a high molecular weight polymer having a relative viscosity of 2640 DEG to 3 DEG OO is produced. This makes it possible to make the relative viscosity of the finally obtained resin 2.30 or higher and maintain its molecular weight distribution within a good range.

The second and third tanks and subsequent tanks may be stirred tanks that are substantially full of liquid and in which reaction heat is substantially removed by heat transfer using a jacket or coil, but if the polymerization temperature is higher than the above range, Since a low molecular weight polymer is produced, a high molecular weight resin cannot be obtained. If the polymerization temperature is too low, a sufficient polymerization rate cannot be obtained. Furthermore, it has been found that increasing the conversion rate higher than the above range is practically impracticable because the consumption of stirring power becomes enormous.

A tubular polymerization vessel having a built-in static mixer is connected to the outlet of the stirring tank group, and preferably 75% at the outlet of the tubular polymerization vessel.
Polymerization is carried out until the monomer conversion rate is at least 90%. It is possible to remove at least a portion of the polymerization heat in the tubular polymerization vessel by flowing a heat medium through a jacket provided on the outer wall of the tubular polymerization vessel, but if the temperature of the polymerization liquid inside the tube is
This is carried out adiabatically within a range that does not adversely affect the molecular weight distribution of the resin produced.

Furthermore, the jacket of the tubular polymerization vessel can also be used for heating purposes, at least in the first half of the jacket.

It has been found that adiabatic polymerization within the tubular polymerization vessel causes the temperature of the polymerization solution inside the tube to rise, and this rise in temperature reduces the viscosity of the polymerization solution, making it possible to transport the polymerization solution. If the monomer conversion rate at the outlet of the above-mentioned stirred tank group, that is, the conversion rate at the inlet of the tubular polymerization vessel, is less than the above-mentioned value, the adiabatic inside the tubular polymerization vessel will increase due to the increase in the polymerization rate due to the high monomer concentration. This is inconvenient in keeping the reaction within a range that does not adversely affect the molecular weight distribution of the resin produced.

Static mixers that can be used in the tubular polymerization vessel include, for example, the KEX static mixer, the Sulza static mixer, and the Toshi static mixer, but other static mixers can also be used. Also, a combination of some of these may be used.

The monomer conversion rate in the tubular polymerization vessel is preferably such that the monomer conversion rate at the outlet of the stirring tank group is 1/3 or less. This is because in a tubular polymerization vessel where polymerization is carried out at a higher temperature than in a stirred polymerization tank, a polymer with a lower molecular weight is produced than in a stirred polymerization tank, so the molecular weight distribution of the resulting resin is determined by its physical properties. It is desirable that the ratio of the amount of polymer produced in the tubular polymerization vessel to the polymer content at the outlet of the stirring tank group is not unnecessarily large in order to keep it within a range that does not adversely affect. In addition, if the monomer conversion rate at the outlet of the tubular polymerization vessel exceeds 90%, the viscosity of the polymerization liquid in the tubular polymerization vessel becomes extremely large, making it difficult to transfer the liquid by practical means such as transfer using a vacuum pump. Therefore, the monomer conversion rate at the outlet of the tubular polymerization vessel is set to 90% or less.

At the outlet of the tubular polymerization vessel, the polymerization solution polymerized to a conversion of preferably 75 or more and 90 or less is demonomerized by a devolatilization device normally used in bulk continuous polymerization of polystyrene, and then pelletized. As the devolatilization device, a flash type devolatilization tank is most preferable, but other thin film type devolatilization tanks can also be used. However, if the amount of preheating for the devolatilization tank becomes longer, the amount of low molecular weight polymers produced at high temperatures will increase, and the molecular weight distribution of the resulting resin will expand, impairing the physical properties of the product. It is advantageous that the time is as short as possible and the monomer concentration at the inlet of the preheater is as low as possible.

Next, the present invention will be further explained with examples.

However, the present invention is not limited to these examples.

Example 1 Continuous polymerization of styrene was carried out using the apparatus described in the attached drawings. The first polymerization can is 2゜L1, the second polymerization can and the third polymerization can are 2゜L1.
Each polymerization can weighs 5 tons. The tubular polymerization vessel has an inner diameter of 25mm, a length of 2m, and a built-in KEX type static mixer. The polymerization liquid leaving the tubular reactor is heated to 220° C. by a preheater and then devolatilized. The raw material styrene has a flow rate of 3 t/Hr.

White mineral oil and stearic acid were mixed with the molten resin liquid in line 9. The temperature conditions for each polymerization vessel are shown in the table. The product was sampled 50 hours after the start of polymerization, and its physical properties were measured and recorded in the table. In addition, the polymerization liquid from each polymerization can was also sampled at the same time, and the analytical values were recorded in the table.

It was found that the obtained resin had excellent surface falling weight strength.

Example 2 A test was conducted in the same manner as in Example 1, except that the polymerization temperature conditions were different as shown in the table.

The resulting resin was found to have excellent impact strength.

Example 3 A test was conducted using the apparatus shown in the figure, in which the third polymerization can was wiped off. Otherwise, the same test as in Example 1 was conducted except that the polymerization temperature conditions were as shown in the table.

The resulting resin was found to have excellent impact strength.

Comparative Example 1 A test similar to Example 1 was conducted except that the flow rate was 1°8 t/Hr and the polymerization temperature was as shown in the table.

Even if the residence time in the first can was 11 hours, the polymerization rate in the first can did not reach 30%, which was impractical, so subsequent evaluation was discontinued.

Comparative Example 2 A test similar to Example 1 was conducted except that the flow rate was 7 t/Hr and the polymerization temperature was as shown in the table.

The impact strength was weak and comparable to commercially available general-purpose polystyrene.

Comparative Example 3 A test similar to Example 1 was conducted except that the flow rate was 3°57/Hr and the polymerization temperature was as shown in the table. It was found that when the second polymerization can was heated to 95°C, almost no polymerization occurred in the second polymerization can (3% increase in polymerization rate), so subsequent evaluation was discontinued.

Comparative Example 4 A test similar to Example 1 was conducted except that the flow rate was 4°5 t/Hr and the polymerization temperature was as shown in the table.

The impact strength was weak and comparable to commercially available general-purpose polystyrene.

Comparative Example 5 A test similar to Example 1 was conducted except that the flow rate was 3 t/Hr and the polymerization temperature was as shown in the table. The third polymerization can is 95
℃, it was found that there was almost no polymerization (3%) in the third polymerization tank, so further evaluation was discontinued.

Comparative Example 6 A test similar to Example 1 was conducted except that the flow rate was 4.5 A/Hr% and the polymerization temperature was as shown in the table.

The impact strength was weak and comparable to commercially available general-purpose polystyrene.

Comparative Example 7 A test similar to Example 1 was conducted except that the flow rate was 3.51/Hr% and the polymerization temperature was as shown in the table.

The test was discontinued because stirring became difficult due to the increased viscosity of the second polymerization vessel. The viscosity was 2 million (!, p#).

Comparative Example 8 The same test as in Example 3 was conducted except that the length of the tubular polymerization vessel was 3 m and the polymerization temperature conditions were as shown in the table.

It became difficult to send the polymerization liquid to the tubular polymerization vessel using the pump. At this time, the polymerization rate at the outlet of the tubular polymerization vessel was 93%. The relative viscosity of the resin obtained at this point was 2.25, and the molecular weight distribution was 3.6, whereas Mw/Mn was 2.5 in Example 1.2.3, and the falling weight strength was 30cr
n and reed, which was comparable to commercially available general-purpose polystyrene.

In addition, the viscosity at the outlet of the tubular polymerizer is approximately 6 million (! s
It was p*. This is the reason why it is difficult to send liquid to the ponder.

Comparative Example 9 A test was conducted using the apparatus shown in the figure, in which the tubular polymerization vessel was wiped off. The same test as in Example 1 was conducted except that the polymerization conditions were as shown in the table.

The resulting resin had a falling weight strength of 30 cn1, which was comparable to commercially available general-purpose polystyrene.

1. Since a 70% polymer solution was rapidly introduced into the high-temperature preheater, the preheating conditions became harsh, resulting in the formation of low molecular weight substances, lowering the relative viscosity, and broadening the molecular weight distribution, resulting in dropout. It seems that the weight strength has decreased.

In Example 1.2.3, the molecular weight distribution is -Mw/Mn of 2.
It was 3.6 compared to 5.

Comparative Example 10 The polymerization temperature conditions are as shown in the table, and the flow rate is 3°5t/Hr.
The same test as in Example 3 was conducted except that.

The resulting resin had low impact strength, comparable to commercially available general-purpose polystyrene.

However, the above M w 7M n is the ratio of the M weight average molecular weight Mw to the number average molecular weight Mn as measured by glumeation chromatography using a conventional commercially available polystyrene measurement column.

The physical properties in the table are measured using residual monomer: gas chromatography, tensile strength: ASTM D638, MPI: ASTM D-
1238, Vicat softening point: according to JISK6870.

[Brief explanation of the drawing]

The figure is a flow diagram showing an example of implementation of the present invention. 1... Raw material feed line, 2... First polymerization can, 3
-1.3-2.3-3.3-4... Polymerization liquid transfer line, 4... Second polymerization can, 5... Third polymerization can, 6...
Tubular polymerization vessel with built-in static mixer, 7... preheater for devolatilization, 8... devolatilization tank, 9... molten resin transfer line (then converted to red), 10-1. 10-2.10
-3... Polymerization liquid transfer pump, 11... Molten resin transfer pump, 12... Vacuum line. Patent Applicant: Denki Kagaku Kogyo Co., Ltd. Procedural Amendments Commissioner of the Patent Office Kazuo Wakasugi 2. Title of the invention: Method for producing styrenic resin with excellent strength and its polymerization device 3. Relationship with the amended person case Patent applicant's residence Address: 1-4-1 Yurakucho, Chiyoda-ku, Tokyo Claims column and details of the invention (1) The claims are amended as shown in the attached sheet. (2) “Ko\ni” on page 6, line 20 of the specification is changed to “here”
Correct. (31 Correct “ko\niko” to “here” on page 7, line 5 of the specification. (4) “Jacket heat transfer and/or” on page 7, line 14 of the specification is changed to “noyakut Claims 1. In a method for continuously producing styrenic resin by bulk or solution polymerization, the polymerization temperature is first adjusted in a complete mixing stirring polymerization tank. Polymerization is carried out in the range of 100 to 130° C. until the monomer conversion rate is 30 to 60% to produce a polymer with a relative viscosity of 2.40 to 3.00%, and then 1.
Introducing the polymerization solution into two or more stirring polymerization tanks in a row or in a row,
Here, polymerization is carried out at a polymerization temperature in the range of 100 to 150°C until the monomer conversion rate reaches 55 to 75% to produce a polymer with a relative viscosity of 2.50 to 3.00, and then the polymerization solution is transferred to a static mixer. The final resin is introduced into a tubular polymerization vessel with a built-in polymerization vessel, where it is adiabatically combined at a polymerization temperature of 185°C or less until the monomer conversion rate at the outlet of the tubular polymerization vessel does not exceed 90%. The relative viscosity of
A method for producing a styrenic resin with excellent strength, characterized in that the strength is 0 or more. 2. The patent claim consists of two stirring polymerization tanks, and in the second polymerization tank, polymerization is carried out at a polymerization temperature in the range of 100 to 150°C until the monomer conversion rate of the polymerization liquid at the outlet of the nuclide reaches 55 to 75%. A method for producing a styrenic resin with excellent strength according to scope 1. 3 Consisting of three or more stirring polymerization tanks, polymerization is carried out in the second polymerization tank at a polymerization temperature in the range of 100 to 140°C to achieve a monomer conversion rate of 70% or less, and a relative viscosity of 24
The method for producing a styrenic resin with excellent strength according to claim 1, which produces a polymer having a molecular weight of 0 to 3.00. 4 Monomer conversion rate at the outlet of the tubular polymerization vessel is 75-90%
A method for producing a styrenic resin having excellent strength according to claim 1. 5 At least two continuous stirring polymerization tanks are connected to a tubular polymerization vessel, and the first stirring polymerization tank is a vertical type that mainly uses heat transfer through a jacket or coil and/or heat removal through boiling point reflux. It is a complete mixing type stirring tank, and the other stirring tank is a substantially full liquid type tank, and the reaction heat is substantially removed by a jacket or coil, etc., and the tubular polymerization vessel is A continuous polymerization device for styrenic resin that has a built-in static mixer and a jacket.

Claims (1)

[Claims] 1. In a method for continuously producing styrenic resin by bulk or solution polymerization, first, a monomer conversion rate of 30 to 60% is achieved at a polymerization temperature in the range of 100 to 130°C in a completely mixed stirred polymerization tank. Polymerization is carried out to produce a polymer having a relative viscosity of 2.40 to 3.00, and then the polymerization solution is introduced into one or two or more consecutive stirring polymerization tanks, where the polymerization temperature is 100 to 150. Polymerization is carried out in the temperature range of 55 to 75% of the monomer to produce a polymer with a relative viscosity of 2.5 to 3.00, and then the polymerization solution is transferred to a tubular polymerization vessel with a built-in static mixer. Lead me to this
The relative viscosity of the final resin obtained by polymerizing adiabatically at a polymerization temperature of 185°C or lower to an extent that the monomer conversion rate at the outlet of the tubular polymerization vessel does not exceed 90% is 2.30.
A method for producing a styrenic resin with excellent strength, characterized by the above-mentioned properties. 2. The patent claim consists of two stirring polymerization tanks, and in the second polymerization tank, polymerization is carried out at a polymerization temperature in the range of 100 to 150°C until the monomer conversion rate of the polymerization liquid at the outlet of the nuclide reaches 55 to 75%. A method for producing a styrenic resin with excellent strength according to scope 1. 3. Consisting of three or more stirring polymerization tanks, polymerization is carried out in the second polymerization tank at a polymerization temperature in the range of 100 to 140°C to achieve a monomer conversion rate of 70% or less, and a relative viscosity of 2.4.
The method for producing a styrenic resin with excellent strength according to claim 1, which produces a polymer having a molecular weight of 0 to 3.00. 4. The 7-mer conversion rate at the outlet of the tubular polymerization vessel is 75-90%.
A method for producing a styrenic resin having excellent strength according to claim 1. 5. Vertical complete mixing consisting of at least two consecutive stirring polymerization tanks connected to a tubular polymerization vessel, in which heat transfer through the jacket or coil of the first stirring polymerization tank and/or heat removal through boiling point reflux is the main method. Type stirred vessels and other stirred polymerization vessels are substantially liquid-filled vessels in which the reaction heat is substantially removed by jackets or coils, and tubular polymerization vessels are static mixing vessels. If you have a built-in container,
A continuous polymerization device for styrenic resin characterized by having a jacket.