JPH10237111A - Production of styrenic polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method for styrenic polymer that can readily control the polymerization temperature, since heat can be uniformly and efficiently removed, and causes no adhesion of the polymerized powder particles to wall faces of the polymerization tank and to the mixing blades and occurs no agglomeration of polymer particles by adhesion thereof to each other. SOLUTION: In the production of styrene polymer having mainly syndiotactic structure in a synthesizing tank equipped with an agitation mechanism, the polymerization temperature in the synthesizing tank is controlled by blowing a gas and/or a liquid that readily vaporizes, when it comes into contact with the content, into the content in the synthesizing tank, preferably blowing a gas or a liquid into the tank from at least one inlet including the bottom of the synthesizing tank as well as by the agitation mechanism and feeding an inert solvent that is at least partially in the liquid state into the fluidized polymerization content to vaporize the liquid readily vaporizing, when it contacts with the content and the inert solvent in the liquid state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a styrenic polymer, and more particularly to a method for synthesizing a styrenic polymer having a syndiotactic structure, since heat can be removed uniformly and efficiently. The present invention relates to a method for producing a styrenic polymer in which temperature can be easily controlled.

[0002]

2. Description of the Related Art Recently developed styrene-based polymers having mainly a syndiotactic structure (hereinafter sometimes referred to as SPS) are already widely known as engineering plastics having excellent heat resistance and chemical resistance. As a polymerization method, solventless polymerization and slurry polymerization using various catalysts have been proposed.

In the polymerization of SPS, heat of polymerization and heat of stirring are generated at the time of polymerization. However, if the heat removal is insufficient and the temperature control is not performed well, the heat generated on the wall surface of the synthesis tank or the stirring blades is generated. There has been a problem that powder adhesion may occur or agglomeration may occur due to powder adhesion, and stable continuous operation may not be possible. Various methods have been proposed as heat removal methods for solving such a problem. For example, a method in which a jacket is installed in a reactor and heat is removed by flowing a refrigerant through the jacket (Japanese Patent Laid-Open No.
No. 2-75607), a method using a self-cleaning type polymerization reactor as a reactor (Japanese Patent Application Laid-Open No. 02-191609, etc.), and a method in which an inert solvent is in a liquid state during polymerization. And a method of removing the heat by the latent heat of evaporation (Japanese Patent Application Laid-Open No. 07-25906).

However, in the method of flowing a refrigerant in the jacket or the method using a self-cleaning type polymerization vessel, the heat transfer area is small, and when the amount of generated heat becomes large, it becomes difficult to remove the heat. Was not possible. In the method of supplying an inert solvent in a liquid state during polymerization and removing heat by the latent heat of evaporation, although a certain effect is seen, when the synthetic scale is large,
In order to uniformly remove the heat and prevent unevenness in the temperature distribution, the stirring must be intensified. In this case, there is a problem that further heat of stirring is generated, and the heat removal becomes more difficult.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and since the heat can be uniformly and efficiently removed, the polymerization temperature can be easily controlled, and It is an object of the present invention to provide a method for producing a styrene-based polymer that does not cause adhesion of generated powder to a tank wall surface or a stirring blade or clumping due to adhesion of powders.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in such a situation, and as a result, at least partially maintain the flow of the contents existing in the synthesis tank in a good state. It has been found that the above-mentioned object can be achieved by supplying an inert solvent in a liquid state into a synthesis tank and removing heat by latent heat of evaporation. The present invention has been made based on such findings.

That is, the present invention provides the following method for producing a styrene polymer. (1) In a method for producing a styrenic polymer having a syndiotactic structure mainly in a synthesis vessel, at least a gas and / or a gas contained in the contents present in the synthesis vessel.
Alternatively, an inert solvent that is at least partially in a liquid state is supplied into the synthesis tank in a state where the contents are fluidized by means including blowing of a liquid that easily vaporizes by touching the contents, and A method for producing a styrene-based polymer, comprising controlling a polymerization temperature in a synthesis tank by vaporizing a liquid that easily vaporizes by touching an object and an inert solvent in a liquid state. (2) In a method for producing a styrenic polymer having a syndiotactic structure mainly in a synthesis tank, at least a liquid which is easily vaporized by touching the contents in the contents existing in the synthesis tank In a state in which the contents are fluidized, an inert solvent that is at least partially in a liquid state is supplied into the synthesis tank by a means including blowing, and a liquid and a liquid which are easily vaporized by touching the contents. A method for producing a styrenic polymer, comprising controlling the polymerization temperature in a synthesis tank by vaporizing an inert solvent in a state. (3) In the above (1) or (2), the blowing of the gas into the contents and / or the liquid that is easily vaporized by touching the contents is performed by at least one or more of the blowing ports at the bottom of the synthesis tank. The method for producing a styrene-based polymer according to the above (1) or (2), wherein the method is performed from a blowing port. (4) In any one of the above (1) to (3), the liquid which is easily vaporized by touching the contents existing in the synthesis tank and the inert solvent which is at least partially in a liquid state are paraffin. The method for producing a styrenic polymer according to any one of the above (1) to (3), which is a hydrocarbon.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. 1. Styrene polymer targeted by the present invention The styrene polymer targeted by the present invention mainly has a syndiotactic structure.

A syndiotactic structure has a three-dimensional structure.
Syndiotactic structure, ie, from carbon-carbon bonds
A phenyl group or a substituted phenyl group which is a side chain to the main chain to be formed.
Has a steric structure in which phenyl groups are alternately located in opposite directions
And its tacticity is determined by isotope carbon
Nuclear magnetic resonance (¹³C-NMR method). ¹³
Tacticity measured by the C-NMR method is
Existence ratio of multiple structural units following, for example, two
Is diad, 3 is triad, 5 is
Can be indicated by a pentad, but according to the present invention
Styrene polymer having syndiotactic structure and
Is usually at least 75% racemic dyad, preferably
85% or more, or 30% or more in racemic pentad,
Preferably has a syndiotacticity of 50% or more
Polystyrene, poly (alkylstyrene), poly (c
Styrene), poly (halogenated alkylstyrene)
), Poly (alkoxystyrene), poly (vinyl benzoate)
Peroxyesters), their hydrogenated polymers and their blends.
Compounds or copolymers containing these as main components
You. In addition, here, as poly (alkyl styrene),
Poly (methylstyrene), poly (ethylstyrene),
Li (isopropylstyrene), poly (tert-butyl)
Styrene), poly (phenylstyrene), poly (vinyl)
Lunaphthalene), poly (vinylstyrene), etc.
As poly (halogenated styrene), poly (chloros
(Tylene), poly (bromostyrene), poly (fluoros)
(Ethylene). In addition, poly (alkyl halide)
Styrene), such as poly (chloromethylstyrene).
And poly (alkoxystyrene)
(Methoxystyrene), poly (ethoxystyrene), etc.
There is.

Among these, particularly preferred styrene polymers include polystyrene, poly (p-methylstyrene), poly (m-methylstyrene), poly (p-tert-butylstyrene), and poly (p-chlorostyrene). , Poly (m-chlorostyrene), poly (p-fluorostyrene), hydrogenated polystyrene and copolymers containing these structural units.

Specifically, a styrene-p-methylstyrene copolymer containing at least 3 mol% of a p-methylstyrene repeating unit is preferred. This styrenic polymer is not particularly limited in molecular weight, but preferably has a weight average molecular weight of 10,000 or more, more preferably 50 or more.
000 or more. Furthermore, the molecular weight distribution is not limited in its width, and various types can be applied. Here, if the weight average molecular weight is less than 10,000, the thermal properties and mechanical properties of the resulting composition or molded article may be undesirably reduced. 2. In the synthesis tank where the flow polymerization of the contents existing in the synthesis tank is performed, the contents are at least
It is necessary for the contents to flow by means including blowing of a gas or a liquid which is easily vaporized by touching the contents. (1) Fluid state of contents It is necessary that the contents existing in the synthesis tank be in a flowing state. The term “fluid state” as used herein means that all or a part of the contents is in the corner of the synthesis tank. It refers to a state in which it is moving as a whole without staying on a wall or the like. For example, it is desirable that the contents at the upper part move toward the lower part, and conversely, the contents at the lower part make a series of flows such as moving toward the upper part. The contents are, specifically, styrene monomer, produced powder, charged solvent, and the like, and include a mixture of a solid and a liquid, and a liquid impregnated in the solid. In a state in which all or a part of the contents stays at the corners or walls of the synthesis tank, the heat of the staying portion is not sufficiently removed, and as a result, the heat adheres to the walls of the synthesis tank. You will end up in a situation where you do.

In order to obtain a state in which all or part of the contents are moving as a whole without staying in the corners or walls of the synthesis tank, it is necessary to appropriately select the means and conditions for flowing. is there. If the means for flowing and its conditions are severe, for example, if the rotation speed of the stirring blade is too high and the stirring is too intense, the stirring blade cannot serve as a blade,
The contents may adhere to the stirring blade, or the contents may be driven to the corner of the synthesis tank and run idle, and a good fluidized state may not be obtained. Conversely, if the means for flowing and the conditions are not sufficient, only a part of the contents will flow,
It is possible that the vehicle is in a stagnant state as a whole.

In order to obtain a good fluidized state, the fluidizing means should be considered in consideration of the contents of the contents, that is, the proportion of the styrene monomer and the produced powder depending on the conversion of the styrene monomer and the amount of the cooling solvent used. And conditions must be determined. (2) Means for flowing through the contents The contents are brought into the above-mentioned flowing state by means including at least a gas into the contents and / or a blow of a liquid which is easily vaporized by touching the contents. It is necessary to be. The means may be at least one that includes blowing a gas into the contents and / or a liquid that is easily vaporized by touching the contents.
The gas and / or the liquid which is easily vaporized by touching the content may be blown into the content, or simultaneously with the blowing, stirring may be performed by another means such as a stirring blade. As long as the contents are flowing, other means may be used or not besides the blowing, but it is difficult to obtain a sufficient flow state by the blowing alone, especially in the case of a small scale. Therefore, usually, the blowing and the stirring are used in combination.

Blowing of a gas into the contents and / or a liquid which is easily vaporized by touching the contents. (I) In the case of using a gas, any gas which is inert to polymerization may be used. Specifically, an inert gas such as nitrogen is preferably used. (Ii) In the case of using a liquid that is easily vaporized by touching the contents, any liquid that is inert to polymerization may be used. Specifically, for example, paraffinic hydrocarbons such as n-propane, n-butane, i-butane, n-pentane, i-pentane, and n-hexane; and paraffins such as bromomethane, bromoethane, chloroethane, and 1-fluorobutane. Halogen-substituted hydrocarbons, or isomers or mixtures thereof. Among them, paraffinic hydrocarbons are preferably used. (Iii) The gas in the contents or the liquid which is easily vaporized by touching the contents may be used alone or in combination. In particular, when a liquid that easily evaporates by touching the contents is used, the heat is removed from the contents by evaporating the heat of vaporization during the vaporization, which is more preferable. Specifically, the use of the same solvent as that used for cooling, which will be described later, is advantageous from the viewpoint of the process, such as the fact that a condenser for condensing and reusing after vaporization can be shared, which is more preferable. Alternatively, the pressure in the synthesis tank may be reduced, and a styrene monomer may be used. (Iv) The means and method for blowing gas or the like are not particularly limited. However, since the blowing is performed for flowing the contents, it is preferable to perform the blowing so as to be effective. For example, a method in which one or a plurality of nozzles are installed on the bottom or the wall of the synthesis tank and blown continuously therefrom is preferably performed. A gas or a liquid that is easily vaporized by touching the contents from one blow port may be blown simultaneously or separately at different times, and a plurality of blow ports may be provided to blow the gas or touch the contents. The liquid may be blown separately for blowing the liquid which is easily vaporized. (V) The conditions such as the amount of gas blown, the speed, etc. may be appropriately determined in consideration of the contents of the above-mentioned contents. In particular, when stirring is used in combination, the power of stirring can be reduced by blowing gas or the like, and as a result, it is possible to reduce the generation of stirring heat. Therefore, it is desirable to increase the blowing amount. However, if the amount is too large, the contents may be violently blown up to the upper part of the synthesis tank, and it is necessary to appropriately select conditions such as a blowing amount, a speed, and the like so as to obtain a good flow state of the contents. is there.

In the case of stirring The stirring blade is not particularly limited. For example, various types such as a multistage paddle type and a helical ribbon type can be used. Preferably, a double helical ribbon is used. As described above, the stirring conditions are appropriately determined in consideration of the contents of the contents, that is, the content ratio of the styrene monomer and the generated powder, the amount of the cooling solvent used, and the increase due to the liquefaction of the blown gas. I just need. 3. Heat removal by vaporizing the inert solvent In the present invention, the inert solvent is supplied to the content in the fluid state, and when the inert solvent touches the content and evaporates, the content is vaporized from the content. Removes heat by removing heat. (1) The inert solvent used in the present invention is not particularly limited as long as it is volatile at the polymerization temperature, does not inhibit the polymerization activity of the catalyst, and does not participate in the polymerization. Examples of such an inert solvent include, for example, n
-Propane, n-butane, i-butane, n-pentane,
paraffinic hydrocarbons such as i-pentane and n-hexane, bromomethane, bromoethane, chloroethane, 1-
Halogen-substituted paraffin hydrocarbons such as fluorobutane, or isomers thereof, or mixtures thereof, and the like can be given. Further, the vaporized inert solvent is condensed in the condenser, and the condensate can be supplied to the reactor again. (2) At the time of supplying the inert solvent, it is necessary that at least a part of the inert solvent be in a liquid state. Liquidization is performed. At least part of the liquid is supplied into the synthesis tank in a liquid state, and the heat generated by the polymerization and stirring in the synthesis tank is absorbed and vaporized, thereby enabling heat removal. There is no particular restriction on the position to supply,
From the viewpoint of the contact efficiency with the contents, the upper part of the synthesis tank is preferably used. Further, the number of supply ports may be one or more. The inert solvent is used after removing the poisonous substances of the catalyst in the same manner as the styrene-based monomer. 4. Polymerization temperature control When a liquid that easily evaporates by touching the contents and / or an inert solvent in a liquid state evaporates, heat is removed by removing heat of vaporization from the contents, and polymerization in the synthesis tank is performed. It controls the temperature. (1) For blowing for obtaining the above-mentioned flow state,
When an inert gas such as nitrogen is used, heat is removed by the heat of vaporization of the inert solvent. in this case,
The polymerization temperature during the polymerization is controlled by the supply amount of the inert solvent. That is, when the temperature in the reactor becomes higher than the predetermined temperature, the supply amount of the inert solvent is increased, and when the temperature becomes lower than the predetermined temperature, the supply amount of the inert solvent is reduced to thereby increase the inert solvent. What is necessary is just to adjust the amount of vaporization of the active solvent. (2) When a liquid that easily vaporizes by touching the contents is used for blowing to obtain the above-mentioned fluidized state, both the heat of vaporization of the liquid and the heat of vaporization of the inert solvent are used. As a result, heat is removed. In this case, the polymerization temperature may be controlled by appropriately adjusting the supply amounts of both, but there is a restriction that the supply amount of the liquid used for blowing must be within a range that can ensure a good fluid state. Therefore, it is preferable to control the polymerization temperature during the polymerization mainly by the supply amount of the inert solvent. (3) Further, as described above, the polymerization temperature may be controlled only by the heat removal method using heat of vaporization. However, the polymerization temperature is controlled using both the heat removal method using jacket cooling and the heat removal method using latent heat of evaporation. May be. This makes it possible to more effectively remove heat, and it becomes easier to control the polymerization temperature. 4. If the synthesis tank can effectively remove heat by the above method,
The type and shape of the synthesis tank are not particularly limited.

[0016]

EXAMPLES The method for producing a styrenic polymer according to the present invention will be described more specifically with reference to examples. [Example 1] A completely mixed tank reactor (inside diameter: 435 mm, height: 740 mm, internal volume: 100 liters) having double helical blades was heated to 90 ° C and dried in a vacuum for 3 hours. Then, after the reactor was depressurized with nitrogen gas, the temperature was lowered to 80 ° C., and 65 liters of SPS powder, which had been dried in advance by flowing dry nitrogen gas in advance and sufficiently dried, was charged into the reactor, and was further placed under a nitrogen stream for 2 hours. Let dry. Subsequently, stirring was started at a stirring speed of 100 rpm, and the temperature in the reactor was adjusted to 70 ° C. by a jacket.

Thereafter, the introduction of the styrene monomer and the catalyst was started. The charging rates of the styrene monomer and each catalyst were as follows. Styrene monomer 7 liter / hour Methylaluminoxane 74 mmol / hour Triisobutylaluminum 52 mmol / hour Pentamethylcyclopentadienyltrimethoxytitanium 0.74 mmol / hour At the same time as the above-mentioned styrene monomer and catalyst are charged, n is used as an inert solvent. After starting the feeding of pentane into the reactor, it was gradually increased and finally the feeding rate was adjusted to 8 kg / h. Further, supply of n-pentane was started at a rate of 9 kg / hour from a gas blowing nozzle provided at the bottom of the tank. The n-pentane vaporized immediately and, in combination with the stirring with the double helical blade, created a good flow of the contents. At this time, the temperature in the reactor was 69-7.
It could be maintained at 1 ° C.

In supplying n-pentane,
A valve is provided near the reactor, and the supply line is pressurized to n-
The pentane was prevented from being vaporized and supplied in a liquid state into the reactor. [Comparative Example 1] The temperature in the reactor was controlled by an external jacket (70
° C), except that the polymerization reaction was carried out in the same manner as in Example 1.

The difference between the reactor temperature and the jacket temperature fluctuated within a range of 11 to 15 ° C. from the start of the continuous polymerization reaction. The temperature gradually increased, and it was not possible to maintain the predetermined polymerization temperature. When 58 hours had passed, the continuous polymerization operation was stopped.

[0020]

As described above, since the heat can be uniformly and efficiently removed, the control of the polymerization temperature is easy, and the formed powder adheres to the wall surface of the synthesizing tank and the stirring blade, and clumps due to the adherence of the powders to each other. It is possible to provide an excellent method for producing a styrenic polymer which does not cause conversion.

Claims (4)

[Claims] 1. A method for producing a styrenic polymer mainly having a syndiotactic structure in a synthesis tank, wherein at least contact with gas and / or contents in the contents existing in the synthesis tank. In a state in which the contents are fluidized, an inert solvent that is at least partly in a liquid state is supplied into the synthesis tank by means including the blowing of a liquid that evaporates more easily, and the contents are easily touched by touching the contents. A method for producing a styrene-based polymer, comprising controlling a polymerization temperature in a synthesis tank by vaporizing a liquid that evaporates and an inert solvent in a liquid state. 2. A method for producing a styrenic polymer having a predominantly syndiotactic structure in a synthesizing tank, wherein at least the contents in the synthesizing tank are easily vaporized by touching the contents. In a state in which the contents are fluidized, an inert solvent that is at least partly in a liquid state is supplied into the synthesis tank by means including the blowing of the liquid to be mixed, and a liquid that is easily vaporized by touching the contents. And a method for controlling a polymerization temperature in a synthesis tank by vaporizing an inert solvent in a liquid state. 3. The method according to claim 1, wherein at least one or more blows including a blow-off port at the bottom of the synthesis tank are performed by blowing a gas into the contents and / or a liquid which is easily vaporized by touching the contents. The method for producing a styrenic polymer according to claim 1 or 2, wherein the method is carried out by mouth. 4. A liquid according to claim 1, wherein the liquid which is easily vaporized by touching the contents present in the synthesis tank and the inert solvent which is at least partially in a liquid state are paraffin-based. The method for producing a styrenic polymer according to any one of claims 1 to 3, which is a hydrocarbon.