JP4259289B2 - Composite polymerization method - Google Patents

Description

 The present invention relates to a complex polymerization method capable of efficiently obtaining a target polymer in each of a plurality of polymerization reaction steps by utilizing a monomer economically advantageously. More specifically, the target polymer is efficiently used in each of the multiple polymerization reaction steps while effectively using the recovered monomer without imposing a burden on the purification of the monomer recovered from one polymerization reaction step. The present invention relates to a complex polymerization method that can be obtained well.

In the production of various synthetic rubbers, elastomers, resins, etc., a monomer or a monomer mixture (hereinafter referred to as “monomer” together unless otherwise specified) is dissolved in the good solvent. A solution polymerization method in which polymerization is carried out in a good solvent is widely used. In the solution polymerization method, in order to control the stereoregularity and molecular weight of a polymer, it is often performed to keep the conversion rate of a monomer into a polymer (polymerization conversion rate) low below a certain value. The resulting polymer solution is typically treated with a catalyst deactivator and then sent to a polymer separation step. In this polymer separation step, the polymer is separated by a conventional method such as steam stripping or flash distillation. The polymer separated here is sent to a drying step provided outside the system.
On the other hand, after separation of the polymer, in addition to unreacted monomers and oligomers by-produced in the polymerization reaction step, secondary materials such as polymerization solvent, catalyst deactivator, anti-aging agent used in the polymerization reaction step, etc. (Hereinafter referred to as “collected fraction”).

Discarding the collected fraction as it is is disadvantageous from an economic point of view and is not allowed from environmental considerations. Therefore, trace impurities are removed from the recovered fraction and separated into components such as monomers and polymerization solvents (hereinafter referred to as “components such as recovered monomer”) by treatment such as washing, distillation, and centrifugation, It is common to reuse these.
For example, in Patent Document 1, in a continuous polymerization method of isoprene, isoprene containing cyclopentadiene which is a polymerization inhibitor is polymerized, and then cyclopentadiene contained in the recovered fraction is removed by a specific method to form a polymerization system. Unreacted isoprene and the polymerization solvent are reused while keeping the concentration of cyclopentadiene in the supplied isoprene from exceeding a certain value.

Means for removing unnecessary impurities from unreacted monomers and solvents and separating and recovering the desired components such as recovered monomers include removing impurities by washing, removing impurities by reacting with specific compounds, etc. Although the method is also performed, it is often by simple distillation or extractive distillation.
When impurities are removed by reacting with specific compounds, new problems may occur in the processing of the obtained reaction products. Also, in the case of distillation, particularly when the target compound to be separated and recovered has a boiling point close to that of the compound to be removed, the separation is not easy, and if the separation is forced, it is economical from the standpoint of equipment and operation. It will be very disadvantageous. In addition, if the recovered monomer or solvent is reused without separating and removing impurities, impurities present in trace amounts gradually accumulate in them, and the impurities are polymerization-inhibiting compounds. In some cases, problems such as inhibition of the progress of polymerization, occurrence of abnormal reactions, and inability to obtain a polymer having desired properties are caused.

JP 56-28207 A

 Under such circumstances, the present inventors reuse components such as a recovered monomer containing a polymerization inhibitory compound easily and economically without relying on a separation and recovery operation such as distillation. We have conducted extensive research on methods. As a result, if components such as recovered monomer obtained from one polymerization reaction step (first polymerization reaction step) are used in another specific polymerization reaction step (second polymerization reaction step), the first It is not necessary to separate and remove the polymerization-inhibiting compound from components such as the recovered monomer containing the polymerization-inhibiting compound from the polymerization reaction step, and this polymerization-inhibiting compound can be efficiently recovered after the second polymerization reaction step. In addition, in the first polymerization reaction step, it is not necessary to reuse the recovered monomer and other components, so there is no accumulation of polymerization-inhibiting compounds, and therefore the desired properties can be obtained. It has been found that the polymer having it can be obtained reliably. The present invention has been completed based on these findings.

Thus, according to the present invention , the Ziegler-Natta type polymerizes the first raw material monomer (M1) that is isoprene containing the polymerization-inhibiting compound (A) that is cyclopentadiene until the polymerization conversion becomes α. From the polymerization reaction product obtained in the first polymerization reaction step (I), the first polymerization reaction step (I), which is an isoprene polymerization reaction step using a catalyst, a polymer (P1) and a recovered fraction are obtained. Next, the recovered fraction is distilled to recover the unreacted first raw material monomer (M1) containing the polymerization inhibitory compound (A ), and the separation step (II) and the separation step (II) are used. Using the unreacted first raw material monomer (M1) containing the polymerization inhibitory compound (A) as a part of the second raw material monomer (M2) which is isoprene and styrene , The polymerization conversion rate of the second raw material monomer (M2) is β (however, And β> α.) A composite polymerization method having a second polymerization reaction step (III), which is a styrene-isoprene block copolymerization reaction step using an alkyl lithium catalyst, is performed until polymerization is completed.

In the composite polymerization method of the present invention, it is preferable to supply substantially the entire amount of the polymerization inhibitory compound (A) obtained in the separation step (II) to the second polymerization reaction step (III).
Furthermore, the composite polymerization method of the present invention may have a separation step (IV) for separating and recovering the polymerization inhibitory compound (A) from the polymerization reaction product after the second polymerization reaction step (III). .
In the composite polymerization method of the present invention, the polymerization conversion rate α in the first polymerization reaction step (I) is preferably 90% by weight or less.
In the composite polymerization method of the present invention, the polymerization conversion rate β in the second polymerization reaction step (III) is preferably 95% by weight or more.
Complex polymerization process of the present invention, the polymerization inhibitory compound (A) is cyclopentadiene, raw monomer (M1) is Ru isoprene der.
In the composite polymerization method of the present invention, the first polymerization reaction step is an isoprene polymerization reaction step using a Ziegler-Natta type catalyst, and the second polymerization reaction step is a styrene-isoprene block copolymerization reaction step using an alkyl lithium catalyst. der Ru.

 According to the composite polymerization method of the present invention, while applying the recovered monomer effectively without imposing a burden on the purification of the monomer recovered from one polymerization reaction step, each of the plurality of polymerization reaction steps, The target polymer can be obtained efficiently.

It will be described in details.
Previously not a, in a first polymerization step (I), the first raw material monomer (M1) is polymerized. Here, the first raw material monomer (M1) does not need to be a single monomer, and may be a mixture of a plurality of monomers.
The first raw material monomer (M1) is obtained by converting the polymerization-inhibiting compound (A) that can inhibit the polymerization when the concentration relative to the first raw material monomer (M1) becomes a certain value or more. It is contained to such an extent that the polymerization of (M1) is not substantially inhibited. In the first polymerization reaction step, the polymerization inhibitory compound (A) functions as a component that lowers the activity of the polymerization catalyst. After the treatment with the catalyst deactivator, the polymerization inhibitory compound (A) returns to the original polymerization inhibitory compound (A). Present in the liquid.
Polymerization inhibitory compound may be a mixture of two or more even one type.

First material monomer can apply multiple coupling polymerization method (M1) is not particularly limited, and specific examples thereof include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2 Diene monomers such as 1,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 2-chloro-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene; Aromatic vinyl monomers such as styrene, α-methylstyrene, vinyltoluene, halogenated styrene, divinylbenzene; acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, monobutyl itaconic acid, itaconic anhydride Α, β-ethylenically unsaturated carboxylic acid monomers such as acid and maleic anhydride; methyl (meth) acrylate, ethyl (meth) acrylate, (meth) acrylic Α, β-ethylenically unsaturated carboxylic acid ester monomers such as butyl, 2-ethylhexyl (meth) acrylate, dimethyl fumarate, diethyl fumarate, dimethyl maleate, diethyl maleate, dimethyl itaconate; acrylonitrile, Α, β-ethylenically unsaturated nitrile monomers such as methacrylonitrile, α-chloroacrylonitrile, α-ethylacrylonitrile, α-cyanoethylacrylonitrile, fumaronitrile; vinyl formate, vinyl acetate, vinyl propionate, isopropenyl acetate, valerin Vinyl ester monomers such as vinyl acetate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl versatate and vinyl pivalate; vinyl halides such as vinyl chloride, vinyl bromide and vinylidene chloride Mer; Monoolefins such as tylene, propylene, 1-butene, 2-butene, 1-pentene, 2-pentene, methylbutene, 4-methyl-1-pentene, 1-hexene, 1-octene, cyclopentene, methylcyclopentene, cyclohexene Can raise body

In multi case polymerization process, polymerization catalyst that can be used is not particularly limited.
In multi case polymerization method, a polymerization method which can be used is not particularly limited, it is preferred first polymerization reaction step (I) is a solution polymerization process.
When the polymerization method is a solution polymerization method, the polymerization solvent used is not particularly limited, and can be appropriately selected according to the monomer used, the polymerization catalyst, and the like. Specific examples thereof include saturated aliphatic hydrocarbons such as pentane, hexane, heptane, and octane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, cycloheptane, and cyclooctane; aromatic hydrocarbons such as benzene, toluene, and xylene. And the like.
Further, in the double focus polymerization method, monomer concentration, polymerization temperature, polymerization time, stirring conditions are not particularly limited to various polymerization conditions such as the reaction atmosphere, the monomer used, the polymerization catalyst, a polymerization solvent, the desired What is necessary is just to select suitably according to the characteristic of this polymer, etc.

The polymerization reaction carried out in the first polymerization reaction step is not particularly limited, but in order to obtain a polymer having desired characteristics, a certain amount of the first raw material monomer used for the polymerization is converted into the polymer. when the a polymerization reaction it is necessary to stop the polymerization (when a polymerization conversion alpha) when, can be suitably applied to multi focus polymerization process.
If the polymerization reaction is stopped when the polymerization conversion rate is low, since the unreacted first material monomer containing polymerizable inhibitory compound (A) it is highly necessary to recover reused after polymerization, double coupling polymerization The method is advantageous.
α is preferably 90% by weight or less, and more preferably 70% by weight or less.

After completion of the first polymerization reaction step (I), the polymer (P1) is separated from the polymerization reaction product, and the unreacted first raw material monomer (M1) and the polymerization inhibitory compound (A) are recovered. The separation step (II) is performed. At this time, you may collect | recover these as a mixture with the solvent used for superposition | polymerization.
In the separation step (II), first, the polymer (P1) is separated from the polymerization reaction product obtained in the first polymerization reaction step (I). The method for polymer separation is not particularly limited, and may be a conventionally known method such as steam stripping or flash distillation.
Next, the recovered fraction obtained after separating the polymer (P1) is subjected to steps such as washing with water, centrifuging, distillation, etc., and it is unnecessary or impossible to reuse catalyst deactivator, anti-aging agent, etc. A trace amount component is removed as needed, and components, such as a collection | recovery monomer containing a polymerization inhibitory compound (A), are obtained. In addition, it is not necessary to remove the above-mentioned trace component dare unless the second polymerization reaction performed in the next second polymerization reaction step (III) is inhibited.

Next, the unreacted first raw material monomer (M1) containing the polymerization inhibitory compound (A) obtained in the separation step (II) is part of the second raw material monomer (M2). And the second polymerization reaction step (III) is performed in which polymerization is performed until the polymerization conversion rate of the second raw material monomer (M2) is β (where β> α).
In the second polymerization reaction step (III), the second raw material monomer (M2) is used. As the second raw material monomer (M2), the same monomer as the first raw material monomer (M1) can be used.
In the second polymerization reaction step (III), components such as a recovered monomer containing the polymerization inhibitory compound (A) obtained as described above can be used. That is, in addition to the unreacted first raw material monomer (M1) containing the polymerization inhibitory compound (A), the solvent used in the first polymerization reaction step is also the second polymerization reaction step (III). Can be used. At this time, the first raw material monomer (M1) contained in the component such as the recovered monomer containing the polymerization inhibitory compound (A) is used in the second polymerization reaction step (III). It will be used as a part of the raw material monomer (M2). That is, the composition of the first raw material monomer (M1) and the second raw material monomer (M2) need not be the same.
Here, the component such as the recovered monomer containing the polymerization inhibitory compound (A) obtained in the separation step (II) may be used as it is in the second polymerization reaction step (III), but is distilled. For example, the polymerization inhibitory compound (A) may be concentrated and then subjected to the second polymerization reaction step (III).
Moreover, it is also possible to divide | segment into two or more fractions from which the kind and content of a polymerization inhibiting compound (A) differ.

A part of the polymerization-inhibiting compound (A) may be supplied to the second polymerization reaction step (III) and the rest may be supplied to other applications. However, after the second polymerization reaction step (III), Since isolation becomes easier, it is preferable to supply as much polymerization-inhibiting compound (A) as possible to the second polymerization reaction step (III).
In addition, components, such as a collection | recovery monomer containing a polymerization inhibitory compound (A), can be used in 1st polymerization reaction process (I) in the range which does not have a trouble.

In the second polymerization reaction step (III), the polymerization is continued until the polymerization conversion rate of the second raw material monomer (M2) becomes β. The polymerization conversion rate β at the end of the polymerization is a suitable value for obtaining a desired polymer from the second raw material monomer (M2), and must be appropriately determined so that α <β. However, it should be as high as possible. In view of economy, it is natural that a high polymerization conversion rate is desirable. However, if this polymerization conversion rate β is high, a recovery unit obtained after separating the polymer from the polymerization reaction solution obtained in the second polymerization reaction step is used. The concentration of the polymerization-inhibiting compound (A) in the monomer and other components is increased, and the polymerization-inhibiting compound (A) can be efficiently separated from the unreacted second raw material monomer (M2). As a result, the concentration of the polymerization-inhibiting compound (A) contained in the recovered unreacted second raw material monomer (M2) can be efficiently reduced, and the unreacted second raw material monomer When (M2) is recovered and reused in the first polymerization reaction step (I), the second polymerization reaction step (III) or the like, the polymerization is not inhibited.
β is preferably 95% by weight or more, and more preferably 99% by weight or more.

  A method of separating and recovering a polymer, an unreacted second raw material monomer (M2), a solvent, a polymerization inhibitory compound (A) and the like, which are carried out after completion of the second polymerization reaction, from the polymerization reaction product. Is not particularly limited, and a conventionally known method can be used.

Polymerization inhibitory compound (A) is not particularly limited, refers to a broad compound that inhibits polymerization, may be a so-called polymerization inhibitors, and the like.
However, so-called polymerization inhibitors usually have a high boiling point, have a relatively large difference in boiling point from the raw material monomer, or can be separated by water washing, etc. since not very difficult, double coupling polymerization process, when the boiling point and the polymerizable inhibitory compounds of the first material monomer (M1) and the boiling point of (a) is close, in particular, boiling point at atmospheric pressure of above It is suitable when the difference is 20K or less.
In general, petroleum-derived hydrocarbon monomers are often used as raw material monomers for polymers. This hydrocarbon monomer was separated into components by a method such as distillation from a mixture of a polymerizable monomer and a non-polymerizable compound having similar properties and similar properties, particularly close boiling points. Is. Therefore, when the boiling point is close, separation is not easy, and the main component monomer contains a small amount of another polymerizable monomer or non-polymerizable compound. When these other polymerizable monomers and non-polymerizable compounds do not affect the polymerization, they do not cause a significant operational problem apart from the effect on the properties of the resulting polymer. However, if they affect the polymerization, especially if they inhibit the polymerization, they cause problems.

In general, in the polymerization step, it is rare that the raw material monomer can be completely converted into a polymer, and an unreacted monomer remains. Further, from the viewpoint of controlling the polymer properties, it is often performed to stop the polymerization at a low polymerization conversion rate. In these cases, the unreacted raw material monomer is usually recovered and reused. At this time, the unreacted raw material monomer is a compound that inhibits polymerization (polymerization inhibitory compound). Is contained, the concentration of the polymerization-inhibiting compound with respect to the raw material monomer gradually increases as polymerization and unreacted raw material monomer are repeatedly collected and reused, and finally the polymerization is substantially inhibited. As a result, an abnormal reaction and an abnormal characteristic value of the polymer to be produced are caused.
According to the double coupling polymerization method, generated from the first polymerization reaction step (I), polymerizable inhibitory compound first material monomer unreacted containing (A) (M1), a first polymerization Since it is not necessary to reuse it in the reaction step (I), the above-mentioned reaction abnormality and the characteristic value of the polymer to be produced are not caused.

Double if the polymerization method, the degree of polymerization inhibition due to polymerization inhibitory compound (A), in a second polymerization step (III), can be suitably applied to a case smaller than in the first polymerization reaction step (I) .
“The degree of polymerization inhibition is small” means that when the concentration of the polymerization inhibiting substance with respect to the raw material monomer is the same, the final polymerization conversion rate when the polymerization is not intentionally stopped is higher.
That is, double coupling polymerization method, the recovered monomers such component containing the first polymerization step (I) and separation step (II) the through-obtained polymerizable inhibitory compound (A), the raw material monomer When used in the second polymerization reaction step (III) at the same polymerization-inhibiting compound concentration with respect to (M1), the final polymerization conversion rate of the second polymerization reaction is the final polymerization conversion rate of the first polymerization reaction. It can be suitably applied to the case where it becomes higher than the above.
The difference between the final polymerization conversion rate α of the first polymerization reaction and the final polymerization conversion rate β of the second polymerization reaction is more preferably 5 points or more.

In multi case polymerization method, preferred examples, the first polymerization reaction is a polymerization reaction using a Ziegler-Natta catalyst, the second polymerization reaction and a combination of a block copolymerization reaction using an alkali metal organic compound .
As an example of a multi-focus polymerization method applicable polymerizable inhibitory compound (A), mention may be made of cyclopentadiene.
Complex polymerization process of the present invention, the polymerization inhibitory compound is a cyclopentadiene (boiling point 41.5-42 ° C. under atmospheric pressure), the polymerization of isoprene (at 34 ° C.) to the first polymerization reaction using a Ziegler-Natta catalyst a reaction, styrene (same 145 ° C.) to a second polymerization reaction using an alkyl lithium catalyst - Ru complex polymerization process der isoprene block copolymerization reaction. In the present invention, the first raw material monomer (M1) is 2-methyl-1,3 butadiene (isoprene), and the second raw material monomer (M2) is 2-methyl-1,3 butadiene. (Isoprene) and styrene.

In the double engagement polymerization process, the second polymerization step (III) after the polymerization reaction product from polymer (P2) is separated from the polymerization reaction product after the polymer separation, polymerization inhibitory compound (A) It can be separated and recovered.
At this time, since the final polymerization conversion rate in the second polymerization reaction is high, the loss of the unreacted second raw material monomer (M2) can be reduced to separate the polymerization-inhibiting compound (A). In particular, when the polymerization conversion rate is substantially close to 100%, the unreacted second raw material monomer (M2) is substantially not present, so that the polymerization inhibitory compound (A) is separated. There is no loss of the unreacted second raw material monomer (M2).

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In FIG. 1, the first step containing a trace amount of the polymerization-inhibiting compound (A) obtained by purifying the crude raw material monomer mixture containing the first raw material monomer (M1) in the monomer purification step. A first raw material monomer comprising a first raw material monomer (M1), a small amount of a polymerization inhibitory compound (A) and a polymerization solvent by adding a polymerization solvent to one raw material monomer (M1) (M1) A composition was obtained. A catalyst is added to this to conduct polymerization, and at the point of polymerization conversion α, a polymerization terminator is added to terminate the polymerization. In the separation step (II), the polymer (P1) of the first raw material monomer (M1) is obtained, and the recovered fraction obtained after the separation of the polymer (P1) is subjected to distillation or the like to recover the recovered monomer An equal component (unreacted first raw material monomer (M1), polymerization-inhibiting compound (A) and solvent mixture = fraction B) is obtained. This component such as the recovered monomer is used as a part of the second raw material monomer (M2) in the second polymerization reaction step (III). Further, two fractions (a fraction D having a high content and a fraction C having a low content) having different contents of the polymerization inhibiting compound (A) are obtained from the fraction B, It is also possible to supply the second polymerization reaction step (III) and return the fraction C to the first polymerization reaction step (I) for use. By increasing the polymerization conversion rate β in the second polymerization reaction step (III), the concentration of the polymerization inhibiting compound (A) in the recovered monomer and other components after the second polymerization reaction step (III) is increased. Can be separated easily. When the conversion rate in the second polymerization reaction step (III) is substantially 100% by weight, the polymerization-inhibiting compound (A) can be separated very easily.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.
Unless otherwise specified, [parts] and [%] are based on weight.
Moreover, in each figure, CPD is cyclopentadiene and a numerical value shows the number of copies.

[Comparative Example 1] (See FIG. 2)
In 167 parts of isoprene (hereinafter referred to as “fresh isoprene”) having a cyclopentadiene content of 1 ppm obtained by refining the C5 fraction (referred to as “carbon hydrocarbon fraction”) in the monomer purification step, 556 parts was added and the 1st raw material monomer (M1) composition was obtained. A Ziegler-Natta type catalyst (hereinafter simply referred to as “Ziegler catalyst”) consisting essentially of triisobutylaluminum and titanium tetrachloride is added to this, and the first polymerization reaction step (I) is carried out for the first time. When the conversion was 60%, 1.7 parts of methanol was added to terminate the polymerization. In the separation step (II), from 100 parts of polyisoprene, 67 parts of isoprene, 0.000167 parts of cyclopentadiene and 556 parts of butane. And a component such as recovered monomer (fraction B).

This recovered monomer component (fraction B) was added to 100 parts of fresh isoprene to obtain a raw material monomer composition (M1). The amount of cyclopentadiene relative to 100 parts of isoprene at this time is 0.000267 parts. A Ziegler catalyst was added thereto, the second first polymerization reaction step (I) was performed, the polymerization was stopped when the polymerization conversion rate was 60%, and 100 parts of polyisoprene was separated in the separation step (II). Got. On the other hand, the obtained component such as recovered monomer (fraction B) consisted of 67 parts of isoprene, 0.000267 parts of cyclopentadiene and 556 parts of butane.
Hereinafter, similarly, the first polymerization reaction step (I) in which this recovered monomer component (fraction B) was added to 100 parts of fresh isoprene and polymerized was repeated.
By repeating this, the concentration of cyclopentadiene in the isoprene used for the first polymerization reaction step (I) increases, and when the concentration of cyclopentadiene reaches 5 ppm, the final polymerization conversion rate decreases to 40%. The Mooney viscosity of the resulting polyisoprene was reduced from the original 85 to 70.

[Comparative Example 2] (See FIG. 3)
167 parts of butane was added to 167 parts of fresh isoprene to obtain a first raw material monomer composition (M1). A Ziegler catalyst was added thereto, the first polymerization reaction step (I) was carried out for the first time, the polymerization was stopped when the polymerization conversion rate was 60%, and 100 parts of polyisoprene was separated in the separation step (II). And a component such as recovered monomer (fraction B) comprising 67 parts of isoprene, 0.000167 part of cyclopentadiene and 556 parts of butane. (The operation so far is the same as the first polymerization reaction step (I) of the first time in Comparative Example 1 and the subsequent separation operation.)
This recovered monomer component (fraction B) is subjected to distillation to obtain a fraction C consisting of 556 parts of butane, 65 parts of isoprene and 0.000067 part of cyclopentadiene, 2 parts of isoprene and 0. A fraction D consisting of 0001 parts was obtained. This fraction D was subjected to a cyclopentadiene removal step by extractive distillation to remove cyclopentadiene and recover 2 parts of isoprene (fraction E).

Fraction C and fraction E were added to 100 parts of fresh isoprene to obtain a first raw material monomer (M1) composition. At this time, the amount of cyclopentadiene with respect to 100 parts of isoprene is 0.0001 part. A Ziegler catalyst was added thereto, the second first polymerization reaction step (I) was performed, the polymerization was stopped when the polymerization conversion rate was 60%, and 100 parts of polyisoprene was separated in the separation step (II). Got. On the other hand, the obtained component such as recovered monomer was composed of 67 parts of isoprene, 0.000167 parts of cyclopentadiene and 556 parts of butane.
Thereafter, similarly, the fraction C and the fraction E obtained from the recovered monomer component (fraction B) were added to 100 parts of fresh isoprene, and the first polymerization reaction step (I) was repeated.
During this repetition, the amount of cyclopentadiene per 100 parts of isoprene subjected to polymerization is maintained at 0.0001 part, the polymerization conversion can be kept at 60%, and the Mooney viscosity of the produced polyisoprene is also The original 85 was maintained.

[Example 1] (see FIG. 4)
167 parts of butane was added to 167 parts of fresh isoprene to obtain a first raw material monomer (M1) composition. A Ziegler catalyst was added thereto, the first polymerization reaction step (I) was carried out for the first time, the polymerization was stopped when the polymerization conversion rate was 60%, and 100 parts of polyisoprene was separated in the separation step (II). And a component such as a recovered monomer comprising 67 parts of isoprene, 0.000167 parts of cyclopentadiene and 556 parts of butane. (The operation so far is the same as the first polymerization reaction step (I) of the first time in Comparative Example 1 and the subsequent separation operation.)
This recovered monomer and other components are subjected to distillation to obtain a fraction C comprising 556 parts of butane, 65 parts of isoprene and 0.000067 part of cyclopentadiene, and a fraction comprising 2 parts of isoprene and 0.0001 part of cyclopentadiene. Minute D was obtained.

This fraction C was added to 102 parts of fresh isoprene to obtain a first raw material monomer (M1) composition. At this time, the amount of cyclopentadiene with respect to 100 parts of isoprene is 0.0001 part. A Ziegler catalyst was added thereto, the second first polymerization reaction step (I) was performed, the polymerization was stopped when the polymerization conversion rate was 60%, and 100 parts of polyisoprene was separated in the separation step (II). Got. On the other hand, the obtained component such as recovered monomer was composed of 67 parts of isoprene, 0.000169 parts of cyclopentadiene and 556 parts of butane.
Similarly, the fraction C consisting of 556 parts of butane, 65 parts of isoprene and 0.000067 parts of cyclopentadiene obtained by subjecting the recovered monomer component (fraction B) to distillation is similarly obtained 102 parts of fresh isoprene. The first polymerization reaction step (I) for polymerization by adding to was repeated.
During this repetition, the amount of cyclopentadiene relative to 100 parts of isoprene subjected to polymerization is maintained at 0.0001 part, the polymerization conversion can be maintained at 60%, and the Mooney viscosity of the produced polyisoprene is also the original 85 could be maintained.
On the other hand, fraction D consisting of 2 parts of isoprene and 0.0001 part of cyclopentadiene is used as it is (that is, without being subjected to the cyclopentadiene removal step). And a second monomer (M2) mixture [100 parts of isoprene, 200 parts of cyclohexane and 0.000198 parts of cyclopentadiene]. This was subjected to block copolymerization with 17 parts of styrene as the second polymerization reaction step (III) using an alkyl lithium catalyst. The polymerization proceeded to a polymerization conversion rate of 100%. The polymerization reaction product was subjected to a separation step (IV) to obtain 117 parts of a styrene / isoprene block copolymer. In addition, cyclohexane containing cyclopentadiene (boiling point 81 ° C. at normal pressure) obtained after recovery of the styrene / isoprene block copolymer is subjected to distillation to separate it into cyclopentadiene and cyclohexane. Discharged outside. Cyclohexane was repeatedly used in the second polymerization reaction step (III).

According to the composite polymerization method of the present invention, as shown in Comparative Example 1, components such as recovered monomers separated and recovered after the first polymerization reaction step (I) are circulated to the first polymerization reaction step (I). There is no accumulation of the polymerization-inhibiting compound (A) as in use, and therefore, reaction abnormality in the first polymerization reaction step (I) can be prevented.
Further, according to the composite polymerization method of the present invention, as shown in Comparative Example 2, the isoprene / cyclopentadiene mixture (both components have a boiling point difference of about 8 to 9 ° C.) (fraction D) to cyclopentadiene. Therefore, the process can be used as it is in the second polymerization reaction step, so that the burden on the apparatus is small, the operation is simple and economical.
Furthermore, according to the composite polymerization method of the present invention, the polymerization inhibitory compound (A) may be separated from a solvent having a large boiling point difference after the second polymerization reaction step (III) (both cyclohexane and cyclopentadiene components). The difference in boiling point is about 39 to 40 ° C.), the burden on the apparatus is small, the operation is simple and economical.

It is a figure which shows the concept of a complex polymerization method . This is an example (Comparative Example 1) in which the unreacted first raw material monomer (M1) from the first polymerization reaction step (I) is recycled to the first polymerization reaction step (I). A component such as a monomer recovered from the first polymerization reaction step (I), a mixture of the unreacted raw material monomer (M1) and the polymerization inhibitory compound (A), and an unreacted raw material monomer ( This is an example (Comparative Example 2) including a step of separating into a mixture of M1), a polymerization inhibitory compound (A) and a solvent, and separating and removing the polymerization inhibitory compound (A) from the former mixture by extractive distillation. Shows a composite polymer how the present invention (Example 1).

Claims (5)

In the isoprene polymerization reaction step using a Ziegler-Natta type catalyst, the first raw material monomer (M1) which is isoprene containing the polymerization inhibitory compound (A) which is cyclopentadiene is polymerized until the polymerization conversion rate becomes α. A first polymerization reaction step (I), a polymer (P1) and a recovered fraction are obtained from the polymerization reaction product obtained in the first polymerization reaction step (I), and then the recovered fraction is distilled. Separation step (II) for recovering the unreacted first raw material monomer (M1) containing the polymerization inhibitory compound (A) , and the polymerization inhibitory compound obtained in the separation step (II) ( The unreacted first raw material monomer (M1) containing A) is used as a part of the second raw material monomer (M2) which is isoprene and styrene, and the second raw material monomer ( The polymerization conversion rate of M2) is β (where β> α). Complex polymerization process having a second polymerization reaction step isoprene block copolymer reaction step (III) - the polymerization of styrene using alkyllithium catalyst.   The method for complex polymerization according to claim 1, wherein substantially the entire amount of the polymerization inhibitory compound (A) obtained in the separation step (II) is supplied to the second polymerization reaction step (III).   The composite polymerization according to claim 1 or 2, further comprising a separation step (IV) for separating and recovering the polymerization inhibitory compound (A) from the polymerization reaction product after the second polymerization reaction step (III). Method. Complex polymerization process according to any one of claims 1 to 3 polymerization conversion in the first polymerization step (I) alpha is characterized in that 90 wt% or less. Complex polymerization process according to any one of claims 1 to 4 polymerization conversion ratio in the second polymerization step (III) beta is equal to or less than 95% by weight.

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