JP2002179728A - 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 containing less amount of halogen by suppressing hydrolysis of halogenated hydrocarbons. SOLUTION: This method for producing an isobutylene-based block copolymer comprising a polymer block composed mainly of isobutylene and a polymer block composed mainly of an aromatic vinyl-based monomer is characterized in that a halogen is removed from the polymer by heating the polymer solution in the presence of a base at the time when the monomer conversion rate into polymer reaches over 70 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an isobutylene-based block copolymer having a reduced halogen content while suppressing the decomposition of a halogenated hydrocarbon.

[0002]

2. Description of the Related Art A polymer block containing isobutylene as a main component and a polymer block containing an aromatic vinyl monomer as a main component are obtained by cationically polymerizing isobutylene and an aromatic vinyl monomer such as styrene. For example, US Pat. No. 4,946,899 discloses a method for producing an isobutylene-based block copolymer comprising a mixture of methyl chloride and methylcyclohexane in a mixed solvent.

[0003] Japanese Patent Publication No. 7-59601 also discloses a method for producing an isobutylene block copolymer comprising an isobutylene polymer block and a styrene polymer block in a mixed solvent comprising methylene chloride and hexane. .

In general, when halogens derived from a polymerization initiator and a Lewis acid as a polymerization catalyst remain in a polymer, hydrogen halide tends to be generated in a step of removing a polymerization solvent from a polymer solution by an evaporation operation. There is.
Since hydrogen halide is a strong acid, if it is left in a product, it is not only unfavorable in quality, but it also exposes a production plant or resin processing equipment to a corrosive environment. Therefore, hydrogen halide must be removed as much as possible.

[0005] However, although the above-mentioned heat treatment alone can remove the halogen, the generated hydrogen halide is a strong acid and equipment corrosion of the production plant is inevitable. Is required.

On the other hand, halogenated hydrocarbons suitably used for isobutylene-based block copolymers tend to easily generate alcohols by hydrolysis in the presence of a base. Such alcohols are typical polymerization inhibitors, and it is necessary to remove the alcohols by distillation, adsorption, or the like when recycling the polymerization solvent recovered by evaporation. Therefore, the production of alcohols due to the hydrolysis of the halogenated hydrocarbon must be suppressed as much as possible.

[0007] It is desired to establish a method for removing halogen from an isobutylene-based block copolymer, which can solve such problems and suppresses the decomposition of a solvent and the corrosion of production equipment.

[0008]

SUMMARY OF THE INVENTION In view of the above situation, the present invention suppresses corrosion and quality deterioration in a manufacturing process,
It is another object of the present invention to provide a method for producing an isobutylene-based block copolymer having a low halogen content and suppressing hydrolysis of a solvent.

[0009]

That is, the present invention provides an isobutylene block copolymer comprising a polymer block mainly composed of isobutylene and a polymer block mainly composed of an aromatic vinyl monomer. A production method, wherein the halogen is eliminated from the polymer by heating the polymer solution in the presence of a base after the polymerization conversion of the monomer reaches 70% by weight or more. A method for producing an isobutylene-based block copolymer,
Preferably, a basic aqueous solution is mixed with the polymer solution and heated. The heating temperature during the heating is 100 ° C. to 18
The heating temperature is preferably 0 ° C. and the heating time is within 360 minutes, but the heating temperature is more preferably 100 ° C. to 120 ° C. As the base (including the base used for the base aqueous solution), LiOH, NaOH, KOH, Ca (O
It is preferable to use at least one selected from the group consisting of H) ₂ , Ba (OH) ₂ and Al (OH) ₃ .

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The isobutylene-based block copolymer referred to in the present invention is composed of a polymer block mainly composed of isobutylene and a polymer block mainly composed of an aromatic vinyl monomer, and specifically, And those obtained by the cationic polymerization of a monomer such as isobutylene and an aromatic vinyl monomer together with an initiator in the presence of a Lewis acid catalyst.

The polymer block mainly composed of isobutylene is usually a polymer block containing 60% by weight or more, preferably 80% by weight or more of isobutylene units. The polymer block mainly composed of an aromatic vinyl monomer is usually a polymer block containing an aromatic vinyl monomer unit in an amount of 60% by weight or more, preferably 80% by weight or more.

The aromatic vinyl monomer is not particularly restricted but includes, for example, styrene, o-, m- or p-methylstyrene, α-methylstyrene, indene and the like. These may be used alone or in combination of two or more. Among them, styrene, p-methylstyrene, α-methylstyrene or a mixture thereof is particularly preferable from the viewpoint of cost.

The Lewis acid catalyst in the present invention is not particularly limited as long as it can be used for cationic polymerization.
Metal halides such as l ₄ , BCl ₃ , BF ₃ , AlCl ₃ , and SnCl ₄ can be mentioned, and among them, titanium tetrachloride (TiCl ₄ ) is preferable.

The polymerization solvent used in the above cationic polymerization is not particularly limited, and a solvent comprising a halogenated hydrocarbon, a non-halogen solvent or a mixture thereof can be used. Preferably, a primary and / or secondary monohalogenated hydrocarbon having 3 to 8 carbon atoms and an aliphatic and / or
Or a mixed solvent with an aromatic hydrocarbon.

The primary and / or secondary monohalogenated hydrocarbon having 3 to 8 carbon atoms is not particularly limited, and examples thereof include methyl chloride, methylene chloride, 1-chlorobutane and chlorobenzene. Among these, 1-chlorobutane is preferred from the viewpoint of the balance of the solubility of the isobutylene-based block copolymer, ease of detoxification by decomposition, cost, and the like.

The aliphatic and / or aromatic hydrocarbon is not particularly restricted but includes, for example, pentane, hexane, heptane, octane, cyclohexane, methylcyclohexane, ethylcyclohexane, toluene and the like. One or more selected from the group consisting of methylcyclohexane, ethylcyclohexane and toluene are particularly preferred.

As the initiator used in the cationic polymerization, it is preferable to use a compound represented by the following general formula (1). (CR ¹ R ² X) n R ³ (1) wherein X represents a halogen atom, an alkoxy group having 1 to 6 carbon atoms, or an acyloxy group. R ¹ and R ² represent a hydrogen atom or a monovalent hydrocarbon group having 1 to 6 carbon atoms, and R ¹ and R ² may be the same or different. R ³ represents a polyvalent aromatic hydrocarbon group or a polyvalent aliphatic hydrocarbon group. n shows the natural number of 1-6. Specific examples of the compound of the general formula (2) include α-chloro-isopropylbenzene,
1,4-bis (α-chloro-isopropyl) benzene [1,4-bis (α-chloro-isopropyl) benzene is also called p-dicumyl chloride].

In the polymerization of the isobutylene-based block copolymer, an electron donor component can be further added, if necessary. Examples of such compounds include pyridines, amines, amides, sulfoxides, esters, and metal compounds having an oxygen atom bonded to a metal atom.

In conducting the actual polymerization, the respective components are mixed under cooling, for example, at a temperature of -100 ° C. or more and less than 0 ° C. In order to balance the energy cost with the stability of the polymerization, a particularly preferred temperature range is from -80C to -30C.

The number average molecular weight of the isobutylene-based block copolymer is not particularly limited, but is preferably 30,000 to 500,000, and more preferably 50,000 to 400,000 in view of fluidity, processability, physical properties and the like. Particularly preferred.

In the present invention, a solution containing an isobutylene-based block copolymer (also referred to as a polymer solution in the present specification) generally refers to an isobutylene-based block copolymer synthesized as described above. And a solution comprising the above-mentioned polymerization solvent and Lewis acid catalyst, wherein the polymerization conversion of the monomer reaches 70% by weight or more, and preferably 90% by weight or more. The polymer solution is not limited to this, and the polymer component may be deactivated and removed using water, alcohol, or the like. The polymerization conversion rate of the monomer is ((weight of monomer component before polymerization) −
It is defined by (weight of residual monomer component) / (weight of monomer component before polymerization) × 100, and is calculated by quantifying the monomer component contained in the polymer solution using gas chromatography. It is possible to

In the present invention, such a polymer solution is mainly heated in the presence of a base and, if necessary, stirred to remove halogens. Preferably, the polymer solution is mixed with a basic aqueous solution. It is good to mix and heat. Hereinafter, titanium tetrachloride as a Lewis acid and 1,4-
The present invention will be described using bis (α-chloro-isopropyl) benzene as an example, but the present invention is not limited thereto.

The deactivation of titanium tetrachloride itself can be achieved only by adding a basic compound (base) or an aqueous solution thereof. However, in decomposing the polymer-bound chlorine derived from 1,4-bis (α-chloro-isopropyl) benzene, the conditions under which titanium tetrachloride is deactivated are not sufficient, and conditions above a certain temperature are indispensable. .

The temperature required for dechlorination is 100 ° C. to 180 °
° C, preferably 100 ° C to 120 ° C. If the temperature is lower than 100 ° C., the deactivation of titanium tetrachloride proceeds, but the elimination of polymer-bound chlorine does not occur. Conversely, if the temperature is 180 ° C. or higher, thermal decomposition of the polymer tends to occur. Also, 120
If the temperature is higher than or equal to ° C., hydrolysis of the halogenated hydrocarbon tends to easily occur in the presence of a base.

On the other hand, the time required for dechlorination is within 360 minutes at least in the range of 100 ° C. to 180 ° C. Although there is no particular problem due to heating for 360 minutes or more, the amount of chlorine in the polymer has reached an equilibrium value, and there is no advantage to continuing heating any longer. Further, in the actual operation, the polymer solution is heated from a temperature range of −80 ° C. to −30 ° C., but there is no particular limitation on the temperature raising condition up to 100 ° C.

As a method for removing hydrochloric acid generated from the polymer solution by heating, it is preferable to heat the polymer solution in the presence of a base (by mixing with a basic aqueous solution).

As the base (including the base used in the aqueous base solution), LiOH, NaOH, KOH, Ca (O
H) ₂ , Ba (OH) ₂ and Al (OH) ₃ can be exemplified. These may be used alone or in combination of two or more. Specifically, it is preferable to add the polymer solution at the time of completion of the polymerization to the above-mentioned aqueous base solution, or to add a basic aqueous solution to the polymer solution and then heat and stir.

According to such a method, deactivation of the catalyst and dechlorination of the polymer can be achieved under the same apparatus and under the same conditions. Since hydrochloric acid does not remain in the polymer solution after the treatment, the solvent is directly evaporated. The following processing can be performed as follows.

The amount of the base used may be a stoichiometric equivalent or more than the total number of moles of chlorine contained in the polymerization initiator and the Lewis acid in the polymer solution.
Considering the safety against equipment corrosion, 1 to 3 equivalents is preferable. If it is less than 1 equivalent, the aqueous solution becomes acidic, so that equipment corrosion cannot be avoided.

As a condition for efficiently promoting the neutralization of hydrogen chloride, it is preferable that the polymer solution is stirred and suspended under a condition that the polymer solution becomes a dispersed phase and the basic aqueous solution becomes a continuous phase. Such conditions can be achieved by setting the weight ratio of the polymer solution to the basic aqueous solution to 3 or less. When the weight ratio of the polymer solution to the basic aqueous solution exceeds 3, the polymer solution tends to be in a continuous phase, and absorption of hydrogen chloride is not efficiently achieved.
By performing such an operation, the generated hydrogen chloride is promptly absorbed by the aqueous phase and neutralized.

The operation will be described more specifically with reference to FIG. 1 as an example.

Inorganic basic aqueous solution: 1: stirring motor,
2: Charge into a vessel having a stirring blade and 3: a baffle to increase stirring efficiency, and then add the polymer solution. The addition position of the polymer solution is not particularly limited, but it is preferable to add the polymer solution to a basic aqueous solution by an insertion tube or the like in order to promote absorption and neutralization of hydrogen chloride in an aqueous phase. The liquid temperature during the treatment is controlled by a 4: thermometer, and the polymer solution and the inorganic basic aqueous solution are adjusted to a required temperature by flowing a heating medium through a jacket.

As described above, in the present invention, as a device used for deactivating the Lewis acid catalyst, a vessel equipped with a stirrer is suitably used. The shape of the stirring blade is not particularly limited, and any blade such as a screw blade, a propeller blade, an anchor blade, a paddle blade, a pitched paddle blade, a turbine blade, and a large lattice blade can be used.

There is no particular limitation on the shape and the like of the vessel used for deactivation as long as it has a function of controlling the internal temperature, and a generally used reaction vessel equipped with a stirrer and a jacket can be used.

The temperature of the solution must be such that the bound chlorine is released from the polymer, and the temperature is 100 ° C. to 180 ° C., preferably 1 ° C.
00 ° C to 120 ° C. The reaction time must be at least within a range of 100 ° C. to 180 ° C. and within 360 minutes. If the reaction time is shorter than this, it is difficult to remove chlorine in the polymer composition.

Residual TiO ₂ and metal salt Na after catalyst deactivation
Since Cl is a solid or aqueous solution that is incompatible with the polymer solution, these are removed together with the aqueous phase by stationary separation. Subsequently, TiO ₂ in the aqueous phase can be separated and removed using a filter such as a filter press, a centrifuge, or the like.

By performing the above operations, the polymerization catalyst and polymer-bound chlorine contained in the polymer solution can be removed as neutral salts, and high-grade equipment materials are used because no hydrogen chloride is generated. No need. Further, it is possible to suppress the generation of alcohols generated by the hydrolysis of the halogenated hydrocarbon, which is an extremely effective means in consideration of recycling of the polymerization solvent.

[0038]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. Chlorine in the polymer shown in this example was quantified by total chlorine analysis (analyzer: TOX-10Σ by Mitsubishi Chemical Co., Ltd.). The monomer polymerization conversion and the composition of the polymer solution were analyzed under the following conditions. Equipment used: Gas chromatograph GC-17A, Shimadzu Corporation Separation column: Capillary column SUPELCOWAX-10 Carrier gas: Helium (100 kPa) Separation conditions: Initial temperature 40 ° C, hold for 2 minutes Heating rate 15 ° C / min (160 ° C), 30 ° C / Min (200 ° C.) Final temperature 200 ° C., held for 3 minutes Injection temperature 260 ° C. Detector temperature 260 ° C. Sample preparation: about 1 g of resin, about 10 g of diluent solvent toluene, about 0.01 g of standard sample decane. (Production Example 1) In a 200-L reaction vessel equipped with a stirrer and a jacket, 61.21 kg of 1-chlorobutane (dried by molecular sieves), 31.63 kg of hexane (dried by molecular sieves), 1,4-bis (α- 64.7 g of chloro-isopropyl) benzene and 122 g of dimethylacetamide were added. The reaction vessel
After cooling to 70 ° C., 16.11 kg of isobutylene were added. Further, 1.5 kg of titanium tetrachloride was added to initiate polymerization, and the mixture was reacted at -70 ° C for 90 minutes while stirring the solution. Then, 7.79 kg of styrene was added to the reaction solution,
Further, a polymer solution in which the reaction was continued for 45 minutes was obtained. As a result of quantifying styrene in the polymer solution, the polymerization conversion of styrene was 94% by weight.

A part of the polymer solution was dissolved in a large excess of methanol /
It was dropped into an acetone mixed solvent to precipitate a polymer. The precipitated polymer was dissolved in toluene to a concentration of about 5% by weight and precipitated again in a large excess of methanol / acetone. The polymer was dried in a vacuum drier at 100 ° C. for 1 hour and analyzed for the amount of chlorine. Chlorine content is 635 weight ppm
Met.

(Production Example 2) In a 10 L separable flask equipped with a stirrer, 2424 g of 1-chlorobutane (dried with molecular sieves), 1275 g of hexane (dried with molecular sieves), 1,4-bis (α-chloro) -Isopropyl) benzene 2.28 g and dimethylacetamide 1.725 g were added. After cooling the reaction vessel to −70 ° C. in an ethanol / dry ice bath, 449 g of isobutylene was added. Further, 52.4 g of titanium tetrachloride was added to initiate polymerization, and the mixture was reacted at -70 ° C for 90 minutes while stirring the solution. Next, 192.5 g of styrene was added to the reaction solution, and a polymer solution in which the reaction was continued for another 45 minutes was obtained. As a result of quantifying styrene in the polymer solution, the polymerization conversion of styrene was 91% by weight.

A part of the polymer solution was dissolved in a large excess of methanol /
It was dropped into an acetone mixed solvent to precipitate a polymer. The precipitated polymer was dissolved in toluene to a concentration of about 5% by weight and precipitated again in a large excess of methanol / acetone. The polymer was dried in a vacuum drier at 100 ° C. for 1 hour and analyzed for the amount of chlorine. The amount of chlorine is 1086 weight pp
m.

(Production Example 3) In a 200-L reaction vessel equipped with a stirrer, 53.2 kg of 1-chlorobutane (dried with molecular sieves), 44.4 kg of methylcyclohexane (dried with molecular sieves), α-chloro-isopropylbenzene 96 g and 54 g of dimethylacetamide were added. After cooling the reaction vessel to -70 ° C, 20.6 kg of isobutylene was added. Further, 2 kg of titanium tetrachloride was added to initiate polymerization, and the mixture was reacted at -70 ° C for 90 minutes while stirring the solution. Next, 4.2 kg of styrene was added to the reaction solution to obtain a polymer solution in which the reaction was continued for another 60 minutes. As a result of quantifying styrene in the polymer solution, the polymerization conversion of styrene was 90% by weight.

A part of the polymer solution was dissolved in a large excess of methanol /
It was dropped into an acetone mixed solvent to precipitate a polymer. The precipitated polymer was dissolved in toluene to a concentration of about 5% by weight and precipitated again in a large excess of methanol / acetone. The polymer was dried in a vacuum drier at 100 ° C. for 1 hour and analyzed for the amount of chlorine. Chlorine content is 695 weight ppm
Met.

Example 1 150 g of the polymer solution obtained in Production Example 1 was washed with the same weight of pure water, and this washing was performed until the aqueous phase became neutral. When butanol in this polymer solution was quantified, it was 47 ppm by weight. Next, 150 g of this polymer solution was charged into a pressure-resistant reactor equipped with a stirring blade, a baffle, and a jacket as shown in FIG. 1, and the liquid temperature was maintained at 100 ° C. 30, 60, 9 after reaching 100 ° C
The polymer solution was sampled at 0, 120, 150, 180, 210 and 240 minutes. The sampled polymer solution was dropped into a large excess of a mixed solvent of methanol / acetone to precipitate the polymer. The precipitated polymer was dissolved in toluene to a concentration of about 5% by weight and precipitated again in a large excess of methanol / acetone. The polymer was dried in a vacuum drier at 100 ° C. for 1 hour and analyzed for the amount of chlorine.
Table 1 summarizes the amounts of chlorine in the polymer. When the composition of the polymer solution after the treatment for 6 hours was analyzed, butanol was found to be 45%.
It was ppm by weight. When the polymer solution sampled in 6 hours is shaken with substantially the same weight of pure water, the aqueous phase becomes p
It showed acidity of about H2.

[0045]

[Table 1] (Example 2) The same experiment as in Example 1 was performed except that the liquid temperature was set to 120 ° C and 140 ° C. The sampling time was 40, 100, 220 minutes after reaching 120 ° C, and 14 minutes.
It is 0, 60, and 120 minutes after reaching 0 ° C. The results are summarized in Table 2. Note that the time is a time from when each set temperature is reached, as in the first embodiment. When butanol in the final sampling solution was quantified in the same manner as in Example 1, it was 45 ppm by weight. When the polymer solution sampled at the final time is shaken with almost the same weight of pure water, the aqueous phase becomes pH
It showed about 2 acidity.

[0046]

[Table 2] (Comparative Example 1) The same experiment as in Example 1 was performed except that the liquid temperature was changed to 65 ° C. The chlorine amount after the treatment for 2 hours was 638 ppm by weight. Further, the polymer solution sampled for 2 hours was shaken with almost the same weight of pure water, but the aqueous phase remained neutral.

Example 3 The same experiment as in Example 1 was carried out except that the polymer solution obtained in Production Example 2 was used and the temperature of the solution was 140 ° C. Note that the sampling time is 3, 120, 240, and 360 minutes after reaching 140 ° C. Table 3 summarizes the amounts of chlorine in the polymer. After 6 hours, the butanol contained in the polymer solution was 56 ppm by weight. When the polymer solution sampled for 6 hours was shaken with substantially the same weight of pure water, the aqueous phase showed an acidity of about pH2.

[0048]

[Table 3] (Comparative Example 2) Polymer solution 1300 obtained in Production Example 2
g, pure water 1500 g and sodium hydroxide 26.6 g were heated to 140 ° C. in the same manner as in Example 1. The polymer solution was sampled 180 and 360 minutes after the temperature reached 140 ° C. Table 4 summarizes the amounts of chlorine in the polymer.

When butanol in the polymer solution was analyzed by GC, it was 0.58% by weight after 3 hours and 2.56% by weight after 6 hours. No rust was found on the metal in the container.

[0050]

[Table 4] Example 4 The same experiment as in Comparative Example 2 was performed except that the liquid temperature was set to 120 ° C. Butanol contained in the polymer solution after 6 hours was 10 ppm by weight or less. No rust was found on the metal in the container.

Example 5 Using the polymer solution obtained in Production Example 3, the same experiment as in Example 1 was carried out except that the temperature of the solution was 140 ° C. Note that the sampling time is 1, 120, 240, and 360 minutes after reaching 140 ° C. Table 5 summarizes the results of the chlorine amount. GC of butanol in polymer solution
As a result, it was found to be 10 ppm by weight or less after 6 hours. When the polymer solution sampled for 6 hours was shaken with substantially the same weight of pure water, the aqueous phase showed an acidity of about pH2.

[0052]

[Table 5]

[0053]

According to the method of the present invention, the decomposition of the polymerization solvent is suppressed, and the halogen contained in the polymer is removed very efficiently, whereby a polyisobutylene-based block copolymer having a small halogen content can be produced. . According to the present invention, an isobutylene-based block copolymer having an extremely small halogen content can be produced without causing corrosion of a production plant and hydrolysis of a solvent.

[Brief description of the drawings]

FIG. 1 shows an apparatus for neutralizing and removing hydrogen halide derived from a polymerization initiator and a Lewis acid in a polymer solution to produce an isobutylene-based block copolymer having a very small halogen content.

[Description of Signs] 1: Stirring motor 2: Stirring blade 3: Baffle 4: Thermometer 5: Jacket 6: Inflow direction of heat medium 7: Polymer solution, basic aqueous solution

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J026 HA02 HA28 HA32 HA39 HB05 HB06 HB28 HB32 HB39 HB45 HB48 HB49 HE01 4J100 AA06P AB02Q AB03Q AB04Q AR10Q CA04 GA02 GA22 GC22 HB39 HD19 HE05 HE13 HE32 HG01

Claims (5)

[Claims] 1. A method for producing an isobutylene block copolymer comprising a polymer block mainly composed of isobutylene and a polymer block mainly composed of an aromatic vinyl monomer, comprising: Polymerization conversion of 70
A method for producing an isobutylene-based block copolymer, wherein halogen is eliminated from a polymer by heating the polymer solution in the presence of a base when the weight reaches at least% by weight. 2. The isobutylene-based block copolymer according to claim 1, wherein a basic aqueous solution is mixed with the polymer solution and heated when the polymerization conversion of the monomer reaches 70% by weight or more. Production method 3. The heating temperature during the heating is 100 ° C. to 180 °.
C. and the heating time is within 360 minutes.
Or the method for producing the isobutylene-based block copolymer according to 2. 4. The method for producing an isobutylene-based block copolymer according to claim 1, wherein the heating temperature is 100 ° C. to 120 ° C. 5. The method according to claim 1, wherein the base is LiOH, NaOH, KOH, Ca
The method for producing an isobutylene-based block copolymer according to any one of claims 1 to 4, wherein the method is at least one selected from the group consisting of (OH) ₂ , Ba (OH) _2, and Al (OH) ₃ .