JP2001323013A - Method for producing isobutylene-based block copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an isobutylene-based block copolymer advantageous in terms of cost with respect to a production process by reducing the amount of a polymerization solvent substantially used and the amount of the waste solvent after polymerization. SOLUTION: In this method for producing an isobutylene-based block copolymer containing an aromatic vinyl-based monomer and isobutylene in a constitutent component, at least one of the polymerization solvent and the unreacted monomer is separated from a mixed solvent solution obtained by removing a polymer from a reaction solution after a polymerization reaction, purified and reused as the polymerization solvent or the monomer to be used in repeatedly producing the isobutylene-based block copolymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an isobutylene-based block copolymer, and more particularly, to a method for preparing a solvent mixture obtained by removing a polymer from a reaction solution after a polymerization reaction. The present invention relates to a method for producing an isobutylene-based block copolymer in which one is reused.

[0002]

2. Description of the Related Art An isobutylene-based block copolymer comprising a polymer mainly composed of isobutylene and a polymer mainly composed of an aromatic vinyl monomer is a cationic polymerizable monomer mainly composed of isobutylene. It can be produced by cationic polymerization of styrene and an aromatic vinyl monomer such as styrene. For example, U.S. Pat. No. 4,946,899 discloses a method for producing methyl chloride and methylcyclohexane in a mixed solvent. Japanese Patent Publication No. 7-59601 also discloses a method for producing an isobutylene-based block copolymer composed of an isobutylene polymer and a styrene polymer in a mixed solvent composed of methylene chloride and hexane.

As a polymerization solvent for producing an isobutylene-based block copolymer, generally, the amount of the polymer to be about 5-35% by weight, that is, about 65-95% by weight of the polymerization reaction solution. Although a corresponding amount is used, a conventionally known production method uses a new polymerization solvent which is not used at all in the polymerization reaction as a polymerization solvent, so that a considerably high solvent material cost is required. Further, there is a problem that it takes a lot of trouble and cost to treat the waste liquid of the solvent after the polymerization reaction.

In addition to the method for producing an isobutylene-based block copolymer, a technique for recovering and reusing a solvent has been proposed. For example, Japanese Patent Application Laid-Open No. 11-080343 discloses a method for producing a polyphenylene ether in which the amount of an aldehyde, ketone, or organic acid in a polymerization solvent is limited to thereby recycle the polymerization solvent containing an alcohol without lowering the catalytic activity. Is disclosed.

[0005] However, isobutylene-based block copolymers can be produced by a living polymerization reaction.
Regarding the living polymerization reaction, even if a very small amount of impurities of about several tens to several hundreds ppm by weight is present in the solvent, the progress of polymerization is inhibited. In the technology, the separation and removal of impurities was insufficient, and there was a problem that a large amount of unreacted monomers remained in the recovered solvent. Therefore, a polymerization solvent suitable for producing an isobutylene-based block copolymer was reused ( Therefore, a method suitable for recycling is desired.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an isobutylene-based block copolymer in which a polymerization solvent contained in a solvent mixture obtained by removing a polymer from a reaction solution after a polymerization reaction and an unreacted monomer are used. An object of the present invention is to provide a method for producing an isobutylene-based block copolymer that can effectively utilize a monomer.

[0007]

SUMMARY OF THE INVENTION The present invention provides a method for producing an isobutylene-based block copolymer containing an aromatic vinyl-based monomer and isobutylene as constituent components. From the removed solvent mixture, the polymerization solvent and at least one of the unreacted monomers are separated and purified,
This is a method for producing an isobutylene-based block copolymer, which is reused as a polymerization solvent or a monomer used when repeatedly producing an isobutylene-based block copolymer.

An isobutylene polymerization reaction in which isobutylene is polymerized to obtain an isobutylene polymer, and a copolymerization reaction in which an aromatic vinyl monomer is copolymerized with the obtained isobutylene polymer to obtain an isobutylene block copolymer. In the method for producing an isobutylene-based block copolymer described above, a polymerization solvent separated and purified from a solvent mixture can be reused as a polymerization solvent for the isobutylene polymerization reaction.

Preferably, the polymerization solvent is separated and purified so that the aromatic vinyl monomer contained in the reused polymerization solvent is 100 ppm by weight or less. It is preferable to separate and purify so that the total amount of impurities becomes 200 ppm by weight or less.

The polymerization solvent used for producing the isobutylene-based block copolymer may contain 50 to 100% by weight of a polymerization solvent to be reused.

Preferably, the polymerization solvent is separated from the solvent mixture by distillation to purify the solvent. The first distillation removes low-boiling impurities, and the second distillation removes high-boiling impurities and unreacted aromatic vinyl. It is preferable to separate and purify the polymerization solvent by removing the system monomer.

Preferably, the difference in boiling point between the polymerization solvent and the impurities is 10 ° C. or more, the difference in boiling point between the polymerization solvent and the aromatic vinyl monomer is 10 ° C. or more, It is preferably a mixed solvent of chlorobutane and hexane.

An isobutylene polymerization reaction in which isobutylene is polymerized to obtain an isobutylene polymer and a copolymerization reaction in which an aromatic vinyl-based monomer is copolymerized with the obtained isobutylene polymer to obtain an isobutylene-based block copolymer. In the method for producing an isobutylene-based block copolymer described above, the unreacted aromatic vinyl-based monomer separated and recovered from the solvent mixture can be reused as a monomer for the copolymerization reaction.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION An isobutylene-based block copolymer has a chain (block) containing isobutylene as a main component.
Is a block copolymer having The block containing isobutylene as a main component can be a copolymer block of isobutylene and a cationic polymerizable monomer other than isobutylene.

The isobutylene block copolymer referred to in the present invention can be composed mainly of a block mainly composed of isobutylene and a block mainly composed of an aromatic vinyl monomer. For example, an isobutylene-based block copolymer having a block containing an aromatic vinyl-based monomer as a main component is composed of a cationic polymerizable monomer component (A) containing isobutylene as a main component and an aromatic vinyl-based monomer. Can be obtained by cationic polymerization of a monomer component (B) having as a main component together with an initiator in the presence of a catalyst.

Specific examples of the method for producing the isobutylene-based block copolymer include, for example, an isobutylene polymerization reaction in which a monomer component (A) is polymerized to obtain an isobutylene polymer, and a monomer is added to the obtained isobutylene polymer. A production method in which the component (B) is copolymerized to carry out a copolymerization reaction to obtain an isobutylene-based block copolymer can be mentioned.

The cationically polymerizable monomer component (A) containing isobutylene as a main component usually has an isobutylene content of 6%.
It is preferably at least 0% by weight, preferably at least 80% by weight. When the content of isobutylene is less than 60% by weight, gas barrier properties and vibration damping properties, which are properties derived from isobutylene, are inferior.

Examples of cationic polymerizable monomers other than isobutylene include aliphatic olefins, dienes,
And vinyl ethers.

The monomer component (B) containing an aromatic vinyl monomer as a main component usually has an aromatic vinyl monomer content of 60% by weight or more, preferably 80% by weight or more. Is preferred. When the content of the aromatic vinyl monomer is 60
When the amount is less than the weight percentage, the balance between physical properties and polymerization characteristics is lowered.

Specific examples of the aromatic vinyl monomer include:
Styrene, o-methylstyrene, m-methylstyrene,
Examples include one or more monomers selected from the group consisting of p-methylstyrene, α-methylstyrene, and indene. Of these, styrene, p-methylstyrene, α-methylstyrene, or a mixture thereof is particularly preferable from the viewpoint of cost.

The monomer other than the aromatic vinyl monomer is not particularly limited, and examples thereof include aliphatic olefins, dienes, and vinyl ethers.

The proportion of the charged amount of the cationically polymerizable monomer component (A) in all the monomers is preferably 40 to 95% by weight, more preferably 50 to 85% by weight. The proportion of the charged amount of the monomer component (B) is preferably 5 to 60% by weight, more preferably 15 to 50% by weight.
% By weight. The ratio of the charged amount of the monomer component (A) is 4
If it is less than 0% by weight, that is, if the monomer component (B) is 60% by weight,
When the amount is more than the weight%, the flexibility tends not to be sufficiently exhibited. Conversely, when the monomer component (A) exceeds 95% by weight,
That is, when the amount of the monomer component (B) is less than 5% by weight, mechanical properties tend not to be sufficiently exhibited.

The weight average molecular weight of the isobutylene-based block copolymer is preferably from 70,000 to 400,000, more preferably from 85,000 to 11,000 from the viewpoint of physical properties.
0000. If the weight average molecular weight is less than 70,000, mechanical properties tend not to be sufficiently exhibited, and
If it exceeds 00, fluidity and processability tend not to be sufficiently exhibited.

In conducting the actual polymerization, a polymerization solvent, a polymerization initiator, a catalyst and each monomer component are cooled and cooled.
For example, mixing is performed at a temperature of -100 ° C or more and less than 0 ° C. It is preferable to select a temperature lower than −30 ° C. because the reaction rate is low under relatively high temperature conditions and side reactions such as a chain transfer reaction occur. Conversely, under low temperature conditions, the solubility of the polymer decreases and the polymer precipitates. Therefore, a more preferable temperature range is -80 to -3.
0 ° C.

The reaction is preferably carried out for 60 to 300 minutes. If the reaction time is less than 60 minutes, the desired molecular properties tend not to be obtained without reaching the set molecular weight. If the reaction time is more than 300 minutes, the progress of side reactions becomes remarkable, and the desired physical properties tend not to be obtained.

As the initiator in the present invention, it is preferable to use a compound represented by the following formula (1).

(CR¹R^TwoX)_nR^Three (1) In the formula (1), X represents a halogen atom, an alkyl having 1 to 6 carbon atoms.
A substituent selected from a coxy group or an acyloxy group, R¹
And R^TwoIs a hydrogen atom or 1 of 1 to 6 carbon atoms, respectively.
Valent hydrocarbon group, R¹And R^TwoAre the same but different
May be R ^ThreeIs an n-valent aromatic hydrocarbon group or n
Is a monovalent aliphatic hydrocarbon group, and n represents a natural number of 1 to 6.
You.

Specific examples of the compound of the formula (1) include:
1,4-bis (α-chloroisopropyl) benzene [C
₆ H ₄ (C (CH ₃ ) ₂ Cl) ₂ ], 1,3,5-tris (α-chloroisopropyl) benzene [(ClC (CH
₃ ) ₂ ) ₃ C ₆ H ₃ ]. In addition, 1,4-bis (α-chloroisopropyl) benzene is also called dicumyl chloride.

The catalyst used in the present invention is not particularly limited as long as it can be used for cationic polymerization, and examples thereof include Lewis acid catalysts such as TiCl ₄ and BCl ₃ . In terms of ease, TiCl
₄ (titanium tetrachloride) is preferred.

In the production of the isobutylene-based block copolymer, an electron donor component may be further added, if necessary, to bond to a pyridine, amine, amide, sulfoxide, ester, or metal atom. Examples thereof include a metal compound having an oxygen atom, and among them, 2-methylpyridine and dimethylacetamide are preferable from the viewpoint of stabilizing a growing carbon cation during cationic polymerization.

As the polymerization solvent, one having 3 to 8 carbon atoms is used.
A single solvent or a mixed solvent selected from primary and / or secondary monohalogenated hydrocarbons and aliphatic and / or aromatic hydrocarbons can be used. The above carbon number 3
Examples of the primary and / or secondary monohalogenated hydrocarbons include methyl chloride, methylene chloride,
-Chlorobutane, chlorobenzene and the like. Among them, 1-chlorobutane is preferred from the viewpoint of the balance between the solubility of the isobutylene-based block copolymer, ease of detoxification by decomposition, and cost. In addition, examples of the aliphatic and / or aromatic hydrocarbons include pentane, hexane, heptane, octane, cyclohexane, methylcyclohexane, ethylcyclohexane, and toluene. Of these, hexane is preferred from the viewpoint of the balance of the solubility, cost, and dielectric constant of the isobutylene-based block copolymer.

When a mixed solvent of 1-chlorobutane and hexane is used as the polymerization solvent, the mixing ratio (volume ratio) of 1-chlorobutane and hexane is 10:90 to 98: 2 in%.
And more preferably 20:80 to 90:10. 1-chlorobutane mixed ratio is 1
If it is less than 0%, the solubility of the block copolymer tends not to be obtained, and if it exceeds 98%, the molecular weight distribution tends to be narrow and a polymer having a controlled structure tends not to be produced.

The amount of the polymerization solvent used is, for example, 1 to 50% by weight, preferably 5 to 3% by weight, in consideration of the viscosity of the reaction solution obtained after the polymerization reaction and the ease of heat removal.
It can be determined to be 5% by weight.

Since the polymerization solvent is not consumed in the polymerization reaction, the polymerization solvent is separated and recovered from the reaction solution after the polymerization reaction, and is reused (recycled).
If possible, the substantial amount of the polymerization solvent can be greatly reduced, which is very advantageous from an industrial viewpoint.

However, in the production of the isobutylene-based block copolymer, several tens to several hundreds ppm by weight are contained in the polymerization solvent.
Even if minute amounts of impurities and unreacted aromatic vinyl monomers are present, the polymerization of isobutylene is inhibited from progressing, and as a result, a reaction solution after the desired polymerization reaction may not be obtained. Therefore, when the polymerization solvent is used repeatedly, it is necessary to pay attention to the accumulation of impurities and unreacted aromatic vinyl monomers. In the present invention, impurities and unreacted aromatic vinyl monomers are removed by separating and purifying the polymerization solvent from a solvent mixture obtained by removing the polymer from the reaction solution after the polymerization reaction. Here, purification refers to reducing the amounts of impurities and unreacted aromatic vinyl monomers to increase the purity. Examples of the impurities include water, alcohol, and ether. In order to separate and purify the polymerization solvent from the solvent mixture, it is effective to separate and remove these impurities and unreacted vinyl monomers by distillation.

The distillation treatment can be performed by either batch distillation or continuous distillation. For example, in the case of batch distillation, low-boiling impurities are removed by extracting a distillate at the top of the column at the beginning of distillation, and high-boiling impurities and unreacted aromatic vinyl-based unit are obtained by extracting the bottom liquid after distillation. The monomer can be removed and purified. In the case of continuous distillation, depending on the type of impurities to be removed and unreacted aromatic vinyl monomers, removal of impurities and unreacted monomers can be achieved and purified by one or more distillation columns. it can. The distillation treatment is not limited to normal pressure, and operation at reduced pressure is also possible.

In the distillation treatment, the polymerization solvent can be separated and purified from the solvent mixture by refluxing the top distillate. For example, by setting the reflux ratio to 2 or more, preferably 4 or more, highly refined can be obtained.

In the process for producing an isobutylene-based block copolymer of the present invention, it is important to select a polymerization solvent. That is, it is preferable to select, as the polymerization solvent, a substance to be separated and removed, that is, a solvent having a boiling point difference of 10 ° C. or more from impurities or unreacted aromatic vinyl monomers in a solvent mixture that inhibits polymerization. . By this, when producing the isobutylene block copolymer, the polymerization solvent and the unreacted aromatic vinyl monomer are separated and purified from the solvent mixture,
It becomes easy to collect and reuse (recycle use).

Since the polymerization solvent (recovered polymerization solvent) separated and purified by the distillation treatment is again charged into the polymerization tank as a polymerization solvent, a new solvent may be added in an amount lost in removing impurities and unreacted monomers. It is often possible to reduce the amount of polymerization solvent by 50% by weight or more (solvent recycling is 50% by weight or more), and the amount of waste solvent can be reduced in proportion thereto.

As an example, an operation for separating and removing impurities and unreacted styrene when producing an isobutylene-styrene block copolymer using 1-chlorobutane (boiling point 79 ° C.) and hexane (boiling point 69 ° C.) as a polymerization solvent. ,
This will be specifically described with reference to FIG. The solvent mixture obtained by removing the polymer from the reaction solution after the weight reaction is subjected to a low boiling distillation column 1
To remove low-boiling impurities (such as water (azeotrope with 1-chlorobutane or hexane)) from the top of the column and remove the low-boiling distillation purified solvent from the bottom of the column. Next, the low-boiling distillation purified solvent is supplied to the high-boiling distillation column 2, and high-boiling impurities such as high-boiling distillation residual solvent (1-butanol (boiling point 118 ° C) and dibutyl ether (boiling point 142 ° C)) Reaction styrene (boiling point: 145 ° C.) is removed, and the recovered polymerization solvent recovered from the top is reused (recycled) as a polymerization solvent used when repeatedly producing an isobutylene-styrene block copolymer.

In the production of the isobutylene-styrene block copolymer, the conversion of the styrene monomer may not be able to be set high because of the suppression of side reactions.
In the high boiling distillation residual solvent at the bottom of the high boiling distillation column, a large amount of unreacted styrene remains together with high boiling impurities. In a method for producing an isobutylene-based block copolymer, an isobutylene polymerization reaction is performed by polymerizing isobutylene to obtain an isobutylene polymer, and a copolymerization reaction is performed by copolymerizing styrene with the obtained isobutylene polymer to obtain an isobutylene-based block copolymer. However, it is impossible to reuse (recycle) the high-boiling distillation residual solvent containing a large amount of unreacted styrene as a polymerization solvent for the isobutylene polymerization reaction, because styrene hinders the progress of the isobutylene polymerization.

However, since the copolymerization reaction (styrene polymerization) has no adverse effect, the high-boiling distillation residual solvent containing a large amount of unreacted styrene is reused as all or a part of styrene in the copolymerization reaction. (Recycle use). Therefore, the unreacted styrene can be reused (recycled use) together with the reuse (recycled use) of the polymerization solvent, and a cost-effective polymerization solvent and unreacted styrene recycling system can be realized. The aromatic vinyl monomer such as styrene can be separated as a mixture with the polymerization solvent and reused.

[0043]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which, however, are not intended to limit the scope of the present invention. Prior to the examples, analysis methods and the like will be described. Analytical method

(Measurement of molecular weight of block copolymer) The molecular weight of the block copolymer was measured using a GPC system manufactured by Waters (column: Shodex K-804 (polystyrene gel) manufactured by Showa Denko KK). It was measured by gel permeation chromatography. Chloroform was used as a solvent, and the solvent flow rate was 1 mL / min. About 20 mg of a polymer sample to be analyzed was dissolved in 2 mL of chloroform to prepare a sample, and 50 μL was injected into the column. Column temperature was set at 35 ° C. RI as detector
A (differential refractive index) detector was used. The molecular weight of the polymer is
Expressed in terms of polystyrene.

(Solvent composition analysis) The composition of the solvent was determined using a GC-17A manufactured by Shimadzu Corporation (column:
It was measured by gas chromatography using a capillary column (SUPELCOWAX-10). Helium was used as the carrier gas, and the column inlet pressure was 100
kPa was set. 0.1 μL of the solvent to be analyzed was injected into the measuring device. Column initial temperature is 40 ° C, final temperature is 20
It was set to 0 ° C. FID (flame ionization detector) was used as the detector.

(Quantitative determination of water in solvent)
Karl Fischer moisture meter (Made by Kyoto Electronics Industry Co., Ltd.)
K-AII).

Production Example 1 61.2 kg of 1-chlorobutane was placed in a 200 L stirring tank.
Hexane 31.6 kg, p-dicumyl chloride 64.
7 g and dimethylacetamide 122 g were charged. The inside of the stirring tank was cooled to a temperature of −70 ° C., and after adding 16.1 kg of isobutylene, 1.50 k of titanium tetrachloride was added.
g was added to start polymerization and reacted for 90 minutes. Then, 7.79 kg of styrene was added, and the reaction was continued for another 60 minutes. Then, the reaction was stopped by mixing the polymer solution with a large amount of water. The polymer solution separated from the aqueous phase was heated and concentrated to finally obtain an isobutylene-styrene block copolymer and a solvent mixture of 90 kg or more.

Example 1 Purification of 90.0 kg of the solvent mixture described in Production Example 1 was carried out according to FIG.
Was carried out using a distillation column (inner diameter: 134 mm, number of theoretical plates: 10) shown in (1). The solvent mixture was supplied to a distillation column, and low-boiling distillation was performed under a distillation condition of a reflux ratio of 5 for the purpose of separating and removing low-boiling impurities such as moisture. The low-boiling distillation purified solvent recovered from the bottom of the distillation column was supplied again to the same distillation column, and high-boiling distillation at a reflux ratio of 2 was performed for the purpose of separating and removing high-boiling impurities such as 1-butanol and unreacted styrene. The amount of the recovered polymerization solvent recovered from the top of the distillation column was 61.2 kg. The amount of the recovered polymerization solvent is shown in Table 1, and the GC analysis result (impurity composition) of the recovered polymerization solvent is shown in Table 2. This recovered polymerization solvent 6
1.2 kg and 31.6 kg of a new solvent (a solvent in a drum of 1-chlorobutane and hexane that has never been used as a polymerization solvent) were charged into a 200 L polymerization tank, and polymerization was carried out in the same manner as in Production Example 1. As a result, an isobutylene-styrene block copolymer was obtained. Table 3 shows the GPC analysis result (molecular weight) of the obtained polymer.

After reducing the substantial amount of the solvent by 66%, the molecular weight was almost as set (weight-average molecular weight: 85,000).
Above).

Example 2 The same operation as in Example 1 was performed except that only 90.0 kg of the solvent mixture was purified by high-boiling distillation at a reflux ratio of 2. The operation of the high boiling distillation was stopped when the amount of the recovered polymerization solvent purified and recovered reached 70.2 kg. The amount of the recovered polymerization solvent is shown in Table 1, and the GC analysis result (impurity composition) of the recovered polymerization solvent is shown in Table 2. Polymerization was carried out using 70.2 kg of the recovered polymerization solvent and 22.6 kg of a new solvent, and an isobutylene-styrene block copolymer was finally obtained in the same manner as in Production Example 1. Table 3 shows the GPC analysis result (molecular weight) of the obtained polymer.

A polymer having a molecular weight almost as set was able to be obtained after reducing the substantial amount of the solvent by 76%.

Example 3 A high-boiling distillation was purified and recovered, and the recovered polymerization solvent amount was 82.8.
The same operation as in Example 2 was carried out, except that the operation was continued until the pressure reached kg. The amount of the recovered polymerization solvent is shown in Table 1, and the GC analysis result (impurity composition) of the recovered polymerization solvent is shown in Table 2. Polymerization was carried out using 82.8 kg of the recovered polymerization solvent and 10.0 kg of a new solvent, and finally an isobutylene-styrene block copolymer was obtained in the same manner as in Production Example 1. Table 3 shows the GPC analysis result (molecular weight) of the obtained polymer.

A polymer having a molecular weight almost as set was able to be obtained after the substantial use of the solvent was reduced by 89%.

Example 4 Recovered polymerization solvent 70.2 obtained by the same method as in Example 2.
and 8.8 kg of a new solvent, polymerization of isobutylene was carried out. Subsequently, 16.9 kg of a high boiling distillation residual solvent containing a large amount of unreacted styrene and 4.67 kg of new styrene were added to carry out polymerization of styrene. . Recovered polymerization solvent amount,
Table 1 shows the amount of high-boiling distillation residual solvent for the purpose of reusing unreacted styrene, and Table 2 shows the results of GC analysis of the impurity composition in the recovered polymerization solvent and the composition of impurities and unreacted styrene in the high-boiling distillation residual solvent. Shown in An isobutylene-styrene block copolymer was finally obtained in the same manner as in Production Example 1.
Table 3 shows the GPC analysis result (molecular weight) of the obtained polymer.

A polymer having a molecular weight almost as set can be obtained after reducing the substantial amount of the solvent by 90%.

Comparative Example 1 An isobutylene-styrene block copolymer was finally obtained in the same manner as in Production Example 1, except that a whole amount of a new solvent was used as a polymerization solvent. Table 3 shows the GPC analysis result (molecular weight) of the obtained polymer molecular weight.

Although a polymer having a molecular weight almost as set could be obtained, the amount of solvent used and the amount of waste solvent were large.
The operation was disadvantageous in terms of cost.

Comparative Example 2 90.0 kg of the solvent mixture of Production Example 1 was used again for polymerization without purification. Table 2 shows the results of GC analysis (impurity composition) of the solvent mixture. Polymerization was carried out using 90.0 kg of a solvent mixture and 2.8 kg of a new solvent, and finally an isobutylene-styrene block copolymer was obtained in the same manner as in Production Example 1. Table 3 shows the GPC analysis result (molecular weight) of the obtained polymer.

Desired molecular weight (weight average molecular weight: 85,000)
This was presumed to be because a polymer having the above) was not obtained, and impurities and unreacted styrene, which were largely contained in the solvent mixture, inhibited the progress of the polymerization reaction.

Comparative Example 3 The same operation as in Example 2 was carried out except that a high-boiling distillation without reflux was used as a purification method for 90.0 kg of the solvent mixture. In the high-boiling distillation, the recovered polymerization solvent purified and recovered is 50.
The operation was stopped when the weight reached 4 kg. The amount of the recovered polymerization solvent is shown in Table 1, and the GC analysis result (impurity composition) of the recovered polymerization solvent is shown in Table 2. Polymerization was carried out using 50.4 kg of the recovered polymerization solvent and 42.4 kg of a new solvent, and finally an isobutylene-styrene block copolymer was obtained in the same manner as in Production Example 1. Table 3 shows the GPC analysis result (molecular weight) of the obtained polymer.

The molecular weight of the obtained polymer was lower than that of the examples, and it was presumed that unreacted styrene contained in the recovered solvent in an amount of 100 ppm or more inhibited the progress of the polymerization reaction.

[0062]

[Table 1]

[0063]

[Table 2]

[0064]

[Table 3]

[0065]

According to the production method of the present invention, the substantial use amount of the polymerization solvent can be greatly reduced, so that the solvent raw material cost can be considerably reduced. Furthermore, according to the production method of the present invention, the amount of waste liquid treated by the solvent after the polymerization reaction can be significantly reduced, which is extremely advantageous in the production process.

[Brief description of the drawings]

FIG. 1 is a selection diagram showing a flow of one embodiment of a distillation process of a solvent mixture in the present invention.

FIG. 2 is a schematic view of an embodiment of a distillation apparatus used for a distillation process of a solvent mixture in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Low boiling distillation tower 2 High boiling distillation tower 3 Distillation tower 4 Reboiler 5 Condenser

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J026 HA02 HA27 HA32 HA39 HB06 HB45 HB48 HE01 4J100 AA06P AB02Q CA04 GB02 GC02 GC07 GD03

Claims (11)

[Claims] 1. A method for producing an isobutylene-based block copolymer containing an aromatic vinyl-based monomer and isobutylene as constituent components, the method comprising polymerizing a solvent mixture obtained by removing a polymer from a reaction solution after a polymerization reaction. A solvent and at least one of unreacted monomers are separated and purified, and the isobutylene-based block is reused as a polymerization solvent or a monomer used when repeatedly producing an isobutylene-based block copolymer. A method for producing a copolymer. 2. An isobutylene polymerization reaction in which isobutylene is polymerized to obtain an isobutylene polymer, and a copolymerization reaction in which an aromatic vinyl-based monomer is copolymerized with the obtained isobutylene polymer to obtain an isobutylene-based block copolymer. 2. The method for producing an isobutylene-based block copolymer according to claim 1, wherein the polymerization solvent separated from the solvent mixture and purified is reused as a polymerization solvent for the isobutylene polymerization reaction. . 3. The method for producing an isobutylene-based block copolymer according to claim 1, wherein the amount of the aromatic vinyl-based monomer contained in the polymerization solvent to be reused is 100 ppm or less. 4. The method according to claim 1, wherein the total amount of impurities comprising water and / or alcohol and / or ether contained in the polymerization solvent to be reused is 200 ppm by weight or less.
4. The method for producing an isobutylene-based block copolymer according to 2 or 3. 5. The polymerization solvent used for producing the isobutylene-based block copolymer is 5%.
The method for producing an isobutylene-based block copolymer according to claim 1, which is contained in an amount of 0 to 100% by weight. 6. The method for producing an isobutylene-based block copolymer according to claim 1, wherein the polymerization solvent is separated from the solvent mixture by distillation treatment and purified. 7. The polymerization solvent is removed from the solvent mixture by removing low boiling impurities by a first distillation treatment and removing high boiling impurities and unreacted aromatic vinyl monomers by a second distillation treatment. The method for producing an isobutylene-based block copolymer according to claim 6, which is separated and purified. 8. The method for producing an isobutylene-based block copolymer according to claim 6, wherein a difference in boiling point between the polymerization solvent and the impurities is 10 ° C. or more. 9. The method for producing an isobutylene-based block copolymer according to claim 6, wherein the difference in boiling point between the polymerization solvent and the unreacted aromatic vinyl-based monomer is 10 ° C. or more. 10. The method for producing an isobutylene-based block copolymer according to claim 8, wherein the polymerization solvent is a mixed solvent of 1-chlorobutane and hexane. 11. An isobutylene polymerization reaction in which isobutylene is polymerized to obtain an isobutylene polymer and a copolymerization reaction in which an aromatic vinyl-based monomer is copolymerized with the obtained isobutylene polymer to obtain an isobutylene-based block copolymer. The method for producing an isobutylene-based block copolymer according to claim 1, wherein the unreacted aromatic vinyl-based monomer separated from the solvent mixture is reused as a monomer for the copolymerization reaction. A method for producing a polymer.