JP2700189B2 - Method for producing styrenic polymer - Google Patents

Description

The present invention relates to a method for producing a styrene-based polymer, and more particularly, to a method for producing a styrene-based polymer having a stereochemical structure of a polymer chain mainly having a zindiotactic structure. It relates to a method for efficiently manufacturing.

[Problems to be solved by conventional technology and invention]

Conventionally, styrene polymers having a stereochemical structure having an atactic structure and an isotactic structure are well known, but recently, a styrene polymer having a stereochemical structure mainly having a syndiotactic structure has been known. It is being developed, and is disclosed, for example, in Japanese Patent Application Laid-Open No. 62-187708.

However, a styrene-based polymer having a syndiotactic structure has a conversion of 20%
The solidification of the entire system occurs at about the same level, but the polymerization reaction proceeds to a conversion rate of about 70%. Therefore, when a polymerization reaction is carried out in a reactor equipped with a conventional stirring blade such as a paddle blade, when a styrene-based polymer having a syndiotactic structure precipitates from the liquid phase, a large particle having a particle size of about 5 mm or more is obtained. Particles were formed, which caused a decrease in drying efficiency. Further, in a portion where the shearing force by stirring does not reach, these particles are solidified in a lump, and at the end of the polymerization reaction, the inner wall of the reactor, the stirring blade,
There is a problem that the polymer adheres to the in-vessel protrusions such as thermocouples.

In order to facilitate post-treatment of the polymer, the present inventors have made it possible to control the particle size of the produced polymer and to prevent the polymer produced during the polymerization reaction from adhering to the inside of the reactor. Intensive research has been conducted to develop a method which can prevent the styrenic polymer having a syndiotactic structure efficiently.

[Means for solving the problem]

As a result, they have found that the above problem can be solved by performing a polymerization reaction while applying a sufficient shearing force under appropriate temperature conditions. The present invention has been completed based on such findings.

That is, the present invention mainly relates to producing a styrenic polymer having a syndiotactic structure, at 90 ° C.
As means for applying a shearing force at the following temperature, (a) a reactor equipped with a stirring mechanism having a stirring blade composed of double helical ribbon blades, (b) a reactor equipped with a stirring mechanism composed of automatic and revolving blades, (C) Using a reactor equipped with a stirring mechanism composed of a single-shaft rotor or (d) using a horizontal reactor equipped with a stirring mechanism composed of a two-axis rotor, applying a shearing force sufficient to maintain a polydispersed state. Another object of the present invention is to provide a method for producing a styrene-based polymer, which comprises polymerizing styrene or a styrene derivative so as to substantially form a solid polydisperse.

The polymer produced in the present invention is a styrenic polymer having a syndiotactic structure. Here, the predominantly syndiotactic structure in the styrenic polymer means a phenyl group or a substituted phenyl group whose stereochemical structure is mainly a syndiotactic structure, that is, a side chain with respect to a main chain formed from carbon-carbon bonds. Have alternate structures in opposite directions, and their tacticity is determined by nuclear magnetic resonance (13C-NMR) using isotope carbon. Tacticity measured by the 13C-NMR method can be represented by the existence ratio of a plurality of continuous structural units, for example, dyads for two, triads for three, and pentads for five. The term “styrenic polymer having a predominantly syndiotactic structure” as used in the present invention generally means 75% or more, preferably 85% or more in dyad, or 30% or more in pentad (racemic pentad), preferably 50% or more. %
Polystyrene, poly (alkylstyrene), poly (halogenated styrene), poly (alkoxystyrene), poly (vinylbenzoic acid ester) having the above syndiotacticity, a mixture of these, or a copolymer containing these as a main component Here, the poly (alkyl styrene) includes poly (methyl styrene), poly (ethyl styrene), poly (isopropyl styrene), poly (tertiary butyl styrene) and the like, and poly (halogenated styrene). ) Includes poly (chlorostyrene), poly (bromostyrene), poly (fluorostyrene), etc. Poly (alkoxystyrene) includes poly (methoxystyrene), poly (ethoxystyrene), and the like. Of these, particularly preferred styrenic polymers include Polystyrene, poly (p- methyl styrene), poly (m-methylstyrene), poly (p- tertiary butyl styrene), poly (p- chlorostyrene), poly (m-chlorostyrene), poly (p
-Fluorostyrene), and a copolymer of styrene and p-methylstyrene.

Styrenic polymer produced by the method of the present invention,
Generally, the weight average molecular weight is 5,000 or more, preferably 10,000 to 2
0,000,000, number average molecular weight 2,500 or more, preferably 5,000
It has a high syndioctacycity as described above, but after polymerization, it is subjected to deashing treatment with a washing solution containing hydrochloric acid or the like, if necessary, and further washed, dried under reduced pressure, and then washed with methyl ethyl ketone or the like. If the soluble matter is removed by washing with a solvent and the resulting insoluble matter is further treated with chloroform or the like, a highly pure styrene-based polymer having extremely large syndiotacticity can be obtained.

Styrene-based polymers having a predominantly syndiotactic structure as described above include, for example, a catalyst comprising a contact product of a titanium compound and an organoaluminum compound with a condensing agent in an inert hydrocarbon solvent or in the absence of a solvent. Then, it can be produced by polymerizing a styrene monomer (a monomer for the above-mentioned styrene polymer, styrene or a derivative thereof).

Here, there are various titanium compounds to be used as the catalyst, but preferably, a general formula TiRXYZ (I) wherein R is a cyclopentadienyl group, a substituted cyclopentadienyl group or an indenyl group Wherein X, Y and Z are each independently an alkyl group having 1 to 12 carbon atoms,
An alkoxy group, an aryl group having 6 to 20 carbon atoms and 6 carbon atoms
Represents an aryloxy group having from 20 to 20, an arylalkyl group having from 6 to 20 carbon atoms, or halogen. ] It is a titanium compound represented by these. In addition to the titanium compound represented by the above general formula (I), [Wherein, R ¹ and R ² each represent a halogen atom, a carbon number of 1 to 20;
Represents an alkoxy group or an acyloxy group, and k represents 2 to 20. ] May be used.

Further, as the above-mentioned titanium compound, a compound which forms a complex with an ester or an ether may be used.

On the other hand, the contact product of the organoaluminum compound constituting the main component of the catalyst together with the titanium compound and the condensing agent is obtained by contacting various organoaluminum compounds with the condensing agent. Here As the organoaluminum any of various are available, normally the general formula AlR ^{₃ 3} ...... (III) wherein, R ³ represents an alkyl group having 1 to 8 carbon atoms. ] The organic aluminum compound represented by these can be mentioned.

As a condensing agent for condensing this organoaluminum compound, water is typically cited, but any other condensing agent capable of condensing an organoaluminum compound such as alkylaluminum may be used. A typical example of the contact product is a reaction product of a trialkylaluminum compound and water. (Wherein, n represents the degree of polymerization). And a cyclic alkylaluminoxane having a repeating unit represented by

In general, the contact product of an organoaluminum compound such as a trialkylaluminum and water is, together with the above-described chain alkylaluminoxane or cyclic alkylaluminoxane, an unreacted trialkylaluminum, a mixture of various condensation products, and furthermore, These are complexly associated molecules, which are various products depending on the contact conditions between the trialkylaluminum and water.

The reaction between the organoaluminum compound and water at this time is not particularly limited, and may be performed according to a known method. For example, a method in which an organoaluminum compound is dissolved in an organic solvent and then brought into contact with water, a method in which an organoaluminum compound is initially added during polymerization and then water is added, and furthermore, a method in which a metal salt or the like is contained There is a method of reacting water of crystallization, water adsorbed on inorganic or organic substances with an organoaluminum compound, and the like.

When this is used as a catalyst, the above contact product is used alone, and of course, the organoaluminum compound is mixed, and further another organometallic compound is mixed, or the contact product is converted to an inorganic substance. It can also be used in such a form that it is adsorbed or carried on the like.

The amount of the contact product between the titanium compound and the organoaluminum compound and the condensing agent is appropriately determined depending on the type of styrene or styrene derivative to be polymerized, the type of catalyst component, and other conditions. This catalyst also has
Other catalyst components can be added.

In the method of the present invention, the raw material and the catalyst are heated at a temperature not higher than the temperature at which the polymer is fused, that is, at a temperature of 90 ° C. or lower,
At a temperature of ℃, while applying sufficient shearing force to maintain the polydispersed state, the polymerization reaction is carried out by stirring to form a substantially solid polydisperse, thereby producing a styrene-based polymer having a syndiotactic structure. I do.

Here, the stirring during the polymerization reaction is carried out under the polymerization temperature, in a state where the monomers are in a liquid state, or in a state where some of the monomers are not in a liquid state but in a slurry state, or substantially contain other solvents. From the stirring in the low viscosity state of the liquid monomer to the stirring in the course of the polymerization while applying the shearing force in the high viscosity state, finally substantially all of the solid polydispersed, and the solid polydispersed Are performed in the same reactor.

The above-mentioned shearing force, especially the shearing force in a high viscosity state, is necessary to make a solid polydisperse, and varies depending on the degree of polymerization and crystallinity of the polymer, but is generally 0.01 kg / cm ² or more, preferably It is desirable to apply a shear force of 0.02-0.2 kg / cm ² .
In other words, the shearing force to be applied is 0.005 k per raw material styrene monomer using the power consumption as an index.
It is desirable that the value is not less than W, preferably 0.01 to 1.0 kW. As means for applying such a shearing force, (a) a reactor C provided with a stirring mechanism in which the stirring blades P are composed of double helical ribbon blades 1 as shown in FIG.
(B) As shown in FIG. 2, a stirring blade P is provided with a stirring mechanism composed of a rotating and revolving type blade 2, a reactor C. (c) As shown in FIG. 3, the stirring blade P is a uniaxial rotating blade. Or a horizontal reactor C having a stirring mechanism composed of rotating blades 3, 3 with a stirring blade P having two agitating blades P, as shown in FIG. 4 (d). Can be mentioned.

By using such various types of reactors C, by appropriately selecting the rotation speed and torque of the stirring blade P, that is, the output of a driving device such as a motor, in a range of stirring power of 0.8 to 500 kW / m ^3. In addition, the shearing force at the time of polymerization can be set to a required magnitude. This makes it possible to appropriately change the particle size of the produced polymer by changing the shearing force during polymerization, that is, to control the particle size.

In addition, the solid polydisperse means those in a dispersed state such as powder or flake,
More preferably, the powder has a uniform particle size.

〔Example〕

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples.

Example 1 In a tank having an inner volume of 2 l and a tank diameter of 130 mm, a blade width of 13 mm and a clearance of 2
Using a tank reactor equipped with a double helical blade of 0.5 mm, 0.5 l of styrene as a raw material, 22.5 mmol of methylaluminoxane as a catalyst and titanium tetraethoxide 0.
225 mmol was added, and a polymerization reaction was carried out for 2 hours at a reaction temperature of 50 ° C. and a stirring speed of 400 rpm.

Power consumption at this time is 0.2 kW / l (shear force 0.05 kg / cm ² )
Met. As a result, 281 g of a styrene-based polymer (polystyrene) having a homogeneous powdery syndiotactic structure
(62% yield). The syndiotacticity of the product in racemic pentad was 92%. In addition, when the reactor was opened after the reaction and the inside was observed, no adhesion of the product to the inner wall or the blade was observed.

Example 2 In a tank having an inner volume of 5 liters and a tank diameter of 200 mm, a tank-type reactor equipped with a blade-shaped ring type and a rotation / revolution type stirring blade having a clearance of 3 mm was used. A polymerization reaction was carried out for 2 hours using the same raw materials and catalyst as in Example 1. The power consumption at this time is 0.1kW / l (shear force 0.03kg /
cm ² ). As a result, 317 g (yield 70%) of a homogenous powdery styrene-based polymer (polystyrene) having a syndiotactic structure was obtained. The syndiotacticity of this product in racemic pentad was 96%, and the weight average diameter was 3.1 mm. Further, when the inside of the reactor was observed after the reaction, no adhesion of the product to the inner wall or the blade was observed.

Example 3 Using a horizontal twin-screw reactor having an actual volume of 3 liters and a clearance of 5 mm at a rotation speed of 100 rpm, raw materials mixed in the same ratio as in Example 1 were supplied at a rate of 1.5 liter / hour and continuously fed. The polymerization reaction was performed for 4 hours.

Power consumption at this time is 0.3 kW / l (shear force 0.18 kg / cm ² )
Met. As a result, a styrene-based polymer (polystyrene) having a homogeneous powdery syndiotactic structure was obtained. The syndiotacticity of this product in racemic pentad was 94%. In addition, there was no clogging of the reactor during the reaction, and the inside of the reactor was observed after the reaction, but no adhesion of the product to the inner wall or the blade was observed.

Example 4 In Example 2, the revolution speed was set to 120 rpm and the rotation speed was set to 240.
The polymerization reaction was carried out in the same manner as in Example 2 except that the rpm was changed.

The power consumption at this time is 0.15kW / l (shear force 0.035kg / c
m ² ). As a result, a styrene-based polymer (polystyrene) having a homogeneous powdery syndiotactic structure
317 g (70% yield) were obtained. The syndiotacticity of this product in racemic pentad was 96% and the weight average diameter was 1.2 mm. Further, no adhesion of the product to the inner wall or the blade of the reactor was observed.

Comparative Example 1 Polymerization was carried out in the same manner as in Example 1 except that the stirring blade was a paddle blade having a blade width of 65 mm and a blade height of 30 mm. As a result, the yield of styrene-based polymer (polystyrene) having a syndiotactic structure was 158 g (yield was
35%). When the inside of the tank was observed, a large amount of deposits were observed on the inner wall centering on the gas-liquid interface, and adhesion was also observed on the blade surface. Further, the polymer produced has a particle size of 5 to 10
It contained 31g of giant particles of mm.

Comparative Example 2 Polymerization was carried out in the same manner as in Example 1, except that the stirring blade was a Faudler blade and two baffles were provided. As a result, the yield of a styrene polymer having a syndiotactic structure (polystyrene) was 176 g (yield: 39%). When the inside of the tank was observed, a large amount of adhesion was observed on the inner wall, the baffle plate, and the stirring shaft, and the polymer contained 25 g of giant particles having a particle size of 5 to 10 mm.

〔The invention's effect〕

As described above, according to the method of the present invention, the polymerization product accompanying the progress of the polymerization reaction does not adhere to the reaction tank or the stirring blade, etc., and has a powdery mainly syndiotactic structure having a uniform particle size. The styrene-based polymer can be obtained efficiently. Further, by controlling the shearing force by the stirring blade, the particle size of the polymer can be controlled, and post-treatment and the like can be easily performed.

Therefore, the method of the present invention is expected to be effectively used mainly as an industrial production method of a styrene polymer having a syndiotactic structure.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a reactor having double helical ribbon blades, FIG. 2 is an explanatory view of a reactor having rotation and revolution type stirring blades, and FIG. 3 is a reactor having uniaxial rotary blades. FIG. 4 is an explanatory view of a reactor provided with a biaxial rotor. 1: Double helical ribbon blade, 2: Rotating and revolving type stirring blade,
3: Rotating blade, C: Reactor P: Stirring blade

Claims (2)

(57) [Claims] 1. A method for applying a shearing force at a temperature of 90 ° C. or less, mainly for producing a styrenic polymer having a syndiotactic structure, comprising: (a) a stirring mechanism comprising a double helical ribbon blade as a stirring blade. Equipped reactor,
(B) a reactor equipped with a stirring mechanism consisting of automatic and revolving blades; (c) a reactor equipped with a stirring mechanism consisting of single-shaft rotors; or (d) a horizontal reactor equipped with a stirring mechanism consisting of twin-shaft rotors. A method for producing a styrene-based polymer, comprising polymerizing styrene or a styrene derivative so as to substantially form a solid polydisperse while using a reactor and applying a shearing force sufficient to maintain a polydispersed state. 2. The method for producing a styrenic polymer according to claim 1, wherein the shearing force is 0.01 kg / cm ² or more.