JP2020050743A - Method for purifying monomer composition and method for producing polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for purifying a monomer composition capable of removing at least a part of impurities which may inhibit a polymerization reaction contained in a monomer composition containing a polycyclic aromatic vinyl compound. offer. A method for purifying a monomer composition containing a polycyclic aromatic vinyl compound having at least two monocycles selected from the group consisting of aromatic hydrocarbon monocycles and aromatic heteromonocycles. Such a purification method comprises a sulfur removal step of removing sulfur from the monomeric composition. [Selection diagram] None

Description

  The present invention relates to a method for purifying a monomer composition and a method for producing a polymer.

  In recent years, a material derived from a copolymer having a monomer unit having two or more aromatic hydrocarbon monocycles such as vinyl naphthalene and an aliphatic conjugated diene monomer unit has been used in various applications. It is attracting attention as a material.

  Specifically, for example, Patent Document 1 discloses that a metal catalyst is used for an ABA triblock copolymer obtained by copolymerizing a specific vinylnaphthalene and a specific diene. Disclosed are a method for obtaining a hydrogenated block copolymer by performing hydrogenation, and an optical film comprising the hydrogenated block copolymer.

JP 2006-111650 A

  Here, according to the study of the present inventors, in producing a polymer using a monomer composition containing a polycyclic aromatic vinyl compound containing a specific vinyl naphthalene as disclosed in Patent Document 1, It has been clarified that impurities that can be contained in such a polycyclic aromatic vinyl compound can inhibit the progress of the polymerization reaction. However, Patent Literature 1 does not mention at all about the effect that impurities that can be contained in the polycyclic aromatic vinyl compound can have on the polymerization reaction, and further discloses nothing from the viewpoint of reducing the amount of such impurities. I didn't.

Therefore, the present invention provides a monomer composition comprising a polycyclic aromatic vinyl compound, which can remove at least a part of impurities which may inhibit a polymerization reaction. It is intended to provide a purification method.
Another object of the present invention is to provide a method for producing a polymer using a composition containing at least a purified monomer composition containing a polycyclic aromatic vinyl compound.

  The present inventors have conducted intensive studies to achieve the above object. And when forming the polymer using the monomer composition containing the polycyclic aromatic vinyl compound, the present inventors may include the monomer composition containing the polycyclic aromatic vinyl compound as an impurity. The present inventors have newly found that a sulfur substance acts to inhibit the formation of a polymer, and completed the present invention.

  That is, an object of the present invention is to advantageously solve the above-mentioned problems, and a method for purifying a monomer composition of the present invention includes a group consisting of an aromatic hydrocarbon monocyclic ring and an aromatic heterocyclic monocyclic ring. A method for purifying a monomer composition comprising a polycyclic aromatic vinyl compound having at least two single rings selected from the group consisting of a sulfur removal step of removing sulfur from the monomer composition. And As described above, by purifying the monomer composition containing the polycyclic aromatic vinyl compound and removing sulfur, a monomer composition having a high polymerization conversion rate upon polymerization can be obtained.

  Here, in the method for purifying the monomer composition of the present invention, the amount of sulfur contained in the monomer composition in the sulfur removing step is 150 ppm based on the mass of the polycyclic aromatic vinyl compound. It is preferable to set the following. Thus, in the sulfur removal step, by setting the amount of sulfur contained in the monomer composition to 150 ppm or less based on the mass of the polycyclic aromatic vinyl compound, the polymerization conversion rate at the time of polymerization is higher. A monomer composition can be obtained. In addition, the amount of sulfur can be measured by the method described in Examples.

  In the method for purifying a monomer composition of the present invention, the amount of sulfur contained in the sulfur-free monomer composition obtained through the sulfur removal step is contained in the monomer composition before purification. It is preferable that the amount of sulfur is 90% by mass or less. As described above, by removing at least 10% by mass of the sulfur contained in the monomer composition before the sulfur removal in the sulfur removal step, the monomer composition having a higher polymerization conversion rate upon polymerization is obtained. You can get things.

  In addition, the method for purifying a monomer composition of the present invention preferably further includes a halogen removing step of removing halogen from the monomer composition. By performing the halogen removing step in purifying the above-mentioned predetermined monomer composition, a monomer composition having a higher polymerization conversion rate upon polymerization can be obtained.

  Furthermore, in the method for purifying a monomer composition of the present invention, in the halogen removing step, the amount of halogen contained in the monomer composition may be 300 ppm based on the mass of the polycyclic aromatic vinyl compound. It is preferable to set the following. In the halogen removing step, by setting the amount of halogen contained in the monomer composition to 300 ppm or less based on the mass of the polycyclic aromatic vinyl compound, a monomer composition having a higher polymerization conversion rate upon polymerization Can be obtained. In addition, the halogen content can be measured by the method described in Examples.

  Furthermore, in the method for purifying a monomer composition of the present invention, the amount of halogen contained in the halogen-free monomer composition obtained through the halogen removing step is contained in the monomer composition before purification. It is preferably 90% by mass or less of the amount of halogen to be obtained. As described above, in the halogen removing step, at least 10% by mass of the halogen contained in the monomer composition before the halogen removal is removed, whereby the monomer composition having a higher polymerization conversion rate upon polymerization is obtained. You can get things.

  And in the purification method of the monomer composition of the present invention, the polycyclic aromatic vinyl compound may contain vinyl naphthalene. The monomer composition containing vinyl naphthalene can be suitably used for various applications.

  Another object of the present invention is to advantageously solve the above-mentioned problems, and a method for producing a polymer of the present invention is a method for producing a purified polymer obtained according to any of the above-described methods for purifying a monomer composition. It is characterized by comprising a polymerization step of anionically polymerizing the composition (I) containing the monomer composition to obtain a polymer. By performing anionic polymerization of the composition (I), a polymer can be formed at a high polymerization conversion rate.

  Here, in the method for producing a polymer of the present invention, it is preferable that the polycyclic aromatic vinyl compound is copolymerized with an aliphatic conjugated diene compound in the polymerization step. In the polymerization step, a polycyclic aromatic vinyl compound is copolymerized with an aliphatic conjugated diene compound, so that it can be suitably used for various applications, among which it is suitably used for forming an optical component such as an optical film. The resulting copolymer can be obtained.

  In the method for producing a polymer of the present invention, in the polymerization step, (1) the polycyclic aromatic vinyl compound and the aliphatic conjugated diene compound are block-copolymerized to obtain a block copolymer. Or (2) random copolymerization of the polycyclic aromatic vinyl compound with an aliphatic conjugated diene compound to obtain a random copolymer. Depending on the polymer structure such as a block copolymer or a random copolymer, desired properties can be imparted to the polymer, and a polymer that can be suitably applied to various uses can be provided.

According to the present invention, a monomer composition containing a polycyclic aromatic vinyl compound, which can remove at least a part of impurities which may inhibit a polymerization reaction, A purification method can be provided.
Further, according to the present invention, it is possible to provide a method for producing a polymer using a composition containing at least a purified polycyclic aromatic vinyl compound-containing monomer composition.

Hereinafter, embodiments of the present invention will be described in detail.
Here, the purified monomer composition obtained by the method for purifying the monomer composition of the present invention can be suitably used in the production method of the polymer of the present invention.

(Purification method of monomer composition)
The method for purifying the monomer composition of the present invention comprises a monomer comprising a polycyclic aromatic vinyl compound having at least two monocycles selected from the group consisting of an aromatic hydrocarbon monocycle and an aromatic heteromonocycle. A method for purifying a composition. Such a purification method is characterized by including a sulfur removal step of removing sulfur from the monomer composition. In the method for purifying a monomer composition of the present invention, by removing a sulfur substance contained as an impurity in the monomer composition to be purified, the purified monomer composition is polymerized when polymerized. A monomer composition having a high conversion can be obtained. Here, a high polymerization conversion rate when a certain monomer composition is polymerized means that the yield when a polymer is obtained using such a monomer composition is high. Therefore, from the viewpoint of efficiently producing a polymer, a monomer composition having a high polymerization conversion rate upon polymerization is advantageous. Furthermore, the method for purifying the monomer composition of the present invention preferably includes a halogen removing step. Hereinafter, the monomer composition to be purified and various steps that can be included in the method for purifying the monomer composition of the present invention will be described.

<Monomer composition to be purified>
The monomer composition to be purified in the method for purifying the monomer composition of the present invention contains a predetermined polycyclic aromatic vinyl compound and impurities.

<< polycyclic aromatic vinyl compound >>
The polycyclic aromatic vinyl compound is a compound having at least two monocycles selected from the group consisting of an aromatic hydrocarbon monocycle and an aromatic heteromonocycle. Note that two or more monocycles in the polycyclic aromatic vinyl compound may be independent of each other or may be condensed to form a condensed ring. It is preferably present as such. Further, the monomer composition to be purified may contain one or more kinds of polycyclic aromatic vinyl compounds.

  Examples of the aromatic hydrocarbon single ring include a benzene ring and a benzene ring having a substituent. Examples of the substituent include an alkyl group such as a methyl group, a propyl group, and a t-butyl group, and a halogen group such as fluorine, chlorine, and bromine.

  Examples of the aromatic heteromonocyclic ring include, for example, oxadiazole ring, oxazole ring, oxazolopyrazine ring, oxazolopyridin ring, oxazolopyridazyl ring, oxazolopyrimidine ring, thiadiazole ring, thiazole ring, and triazine ring. , Pyranone ring, pyran ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrrole ring and the like.

  And as a polycyclic aromatic vinyl compound, 1-vinylnaphthalene, 2-vinylnaphthalene, vinylanthracene, 1,1-diphenylethylene, etc. are mentioned, for example. Among these, vinyl naphthalene such as 1-vinyl naphthalene and 2-vinyl naphthalene is preferable as the polycyclic aromatic vinyl compound. The monomer composition containing vinyl naphthalene can be suitably used for various applications.

<< impurities >>
Impurities contained in the monomer composition to be purified include sulfur. The sulfur as an impurity is not particularly limited, and may be contained as a sulfur substance such as free sulfur and various sulfur-containing compounds. Examples of impurities other than sulfur include halogen such as fluorine, chlorine, bromine, and iodine, and water. The mode of containing halogen as an impurity is not particularly limited, and various halogen-containing compounds can be mentioned.

  The study of the present inventors has revealed that the effect of sulfur, which can be contained in various aspects, among the impurities, is large with respect to the effect of inhibiting the polymerization conversion rate when the monomer composition is polymerized. Was. Therefore, in the method for purifying a monomer composition of the present invention, it is an essential requirement to perform a sulfur removal step of removing sulfur from the monomer composition.

<Sulfur removal process>
In the sulfur removing step, sulfur is removed from the monomer composition. The method for removing sulfur is not particularly limited, and a method using an adsorbent, a sublimation method, or the like can be employed. Among them, a method using an adsorbent is preferable from the viewpoint of removal efficiency. Specifically, in the method using the adsorbent, sulfur contained in the monomer composition can be removed by bringing the adsorbent into contact with the monomer composition to be purified. Note that an inorganic material such as an inorganic oxide can be suitably used as the adsorbent. More specifically, activated alumina can be suitably used as the inorganic oxide. The sulfur removal step can be performed, for example, under a temperature condition of −80 ° C. or more and 70 ° C. or less, for a treatment time (period) of 0.5 hours or more and 30 days or less.

  In the sulfur removal step, the amount of sulfur contained in the monomer composition is preferably set to 150 ppm or less, more preferably 100 ppm or less, based on the mass of the polycyclic aromatic vinyl compound. By setting the amount of sulfur contained in the monomer composition in the sulfur removal step to be equal to or less than the upper limit, a monomer composition having a higher polymerization conversion rate upon polymerization can be obtained. In addition, the sulfur may be completely removed in the sulfur removing step, that is, the sulfur removing step is performed under the condition that the amount of sulfur contained in the sulfur removed monomer composition after the sulfur removing step becomes 0 ppm. May be. However, from the viewpoint that the time required for the sulfur removal step becomes excessively long, and from the viewpoint of efficiently increasing the polymerization conversion rate at the time of polymerization, the sulfur amount of the sulfur-free monomer composition that has passed through the sulfur removal step is reduced. , 30 ppm or more.

  In the sulfur removal step, the amount of sulfur contained in the sulfur-free monomer composition obtained through the sulfur removal step is set to 90% by mass or less of the amount of sulfur contained in the monomer composition before purification. And more preferably 70% by mass or less. The ratio of the amount of sulfur contained in the sulfur-removed monomer composition that has undergone the sulfur removal step to the amount of sulfur contained in the monomer composition before purification (hereinafter, also simply referred to as “sulfur amount ratio before purification”) By adjusting the value of ()) to the above-mentioned upper limit or less, a monomer composition having a higher polymerization conversion rate upon polymerization can be obtained. Although the reason is not clear, in the sulfur removal step, when the treatment is carried out to the extent that the ratio of the amount of sulfur before purification to the above-mentioned upper limit or less, a sulfur substance having a large inhibitory effect on the polymerization reaction is efficiently removed. It is presumed to be caused by this.

<Halogen removal process>
Furthermore, the method for purifying the monomer composition of the present invention preferably includes a halogen removing step. By performing the halogen removing step, a monomer composition having a higher polymerization conversion rate upon polymerization can be obtained. In the halogen removing step, among the halogens, it is preferable to remove bromine. More specifically, in the halogen removing step, the amount of bromine contained in the monomer composition is set to a preferable range described later. Is preferred. Here, the above-described sulfur removing step and the halogen removing step may be performed in any order. More specifically, one of the sulfur removing step and the halogen removing step may be performed first, and then the other may be performed, or both may be performed simultaneously. The method for removing halogen is not particularly limited, and a method using an adsorbent, a sublimation method, a distillation method, or the like can be employed.

  For example, when the above-mentioned “sulfur removal step” is performed using an adsorbent, the adsorbent may adsorb not only sulfur but also halogen. Therefore, the halogen is also adsorbed to the adsorbent by the operation performed as the sulfur removing step, so that the sulfur removing step and the halogen removing step are substantially simultaneously performed. Thus, the sulfur removing step and the halogen removing step may be performed simultaneously.

  In the halogen removing step, the amount of halogen (preferably, the amount of bromine) contained in the monomer composition is preferably 300 ppm or less, and more preferably 160 ppm or less, based on the mass of the polycyclic aromatic vinyl compound. More preferred. In the halogen removing step, by setting the amount of halogen contained in the monomer composition to the above upper limit or less, a monomer composition having a higher polymerization conversion rate upon polymerization can be obtained. Incidentally, the halogen may be completely removed in the halogen removing step, that is, the halogen removing step is performed under the condition that the amount of halogen in the halogen-free monomer composition obtained through the halogen removing step is 0 ppm. May be. However, from the viewpoint of the time and man-hour required for the halogen removing step and the polymerization conversion rate at the time of polymerization, the halogen content of the halogen-free monomer composition that has undergone the halogen removing step may be 50 ppm or more.

  In the halogen removal step, the amount of halogen (preferably, the amount of bromine) contained in the halogen-free monomer composition obtained through the halogen removal step is reduced by the amount of halogen contained in the monomer composition before purification. The amount (preferably, the amount of bromine) is preferably 90% by mass or less, more preferably 55% by mass or less. The ratio of the amount of halogen contained in the halogen-free monomer composition that has undergone the halogen removing step to the amount of halogen contained in the monomer composition before purification (hereinafter, also simply referred to as “the ratio of halogen amount before purification”) By adjusting the value of ()) to the above-mentioned upper limit or less, a monomer composition having a higher polymerization conversion rate upon polymerization can be obtained.

<Other pretreatment steps>
Further, optionally, a pretreatment step for removing water and the like contained in the monomer composition can be performed. The method for removing water contained in the monomer composition is not particularly limited, and includes a method in which a desiccant made of zeolite such as molecular sieve is brought into contact with the monomer composition. Such a pretreatment step is not particularly limited, and can be performed at any timing.From the viewpoint of increasing the production efficiency, the pretreatment step is performed at the same time as the sulfur removal step and / or the halogen removal step. Is preferred.

(Method for producing polymer)
In the method for producing the polymer of the present invention, the composition (I) containing the purified monomer composition obtained according to the above-described method for purifying the monomer composition of the present invention is anion-polymerized to obtain a polymer. It is characterized by including a polymerization step. By performing anionic polymerization of the composition (I), a polymer can be formed at a high polymerization conversion rate. Although the reason is not clear, since the sulfur substance removed in the sulfur removing step acts to inhibit anionic polymerization among various polymerization modes, the purified monomer that has passed through the sulfur removing step is used. It is presumed that the use of the composition can significantly increase the polymerization conversion rate by anionic polymerization.

<Polymerization step>
In the polymerization step, the composition (I) is anionically polymerized to obtain a polymer. The composition (I) needs to contain a polycyclic aromatic vinyl compound having at least two monocycles selected from the group consisting of the above-mentioned aromatic hydrocarbon monocycles and aromatic heteromonocycles. Then, in the polymerization step, an anionic polymerization using an anionic polymerization catalyst is carried out to obtain a homopolymer composed of only monomer units derived from the polycyclic aromatic vinyl compound or a monopolymer derived from the polycyclic aromatic vinyl compound. A copolymer containing a monomer unit and a monomer unit derived from another compound can be obtained. The anionic polymerization is not particularly limited, and can be performed in an organic solvent under an inert gas atmosphere such as a nitrogen gas.

  In the polymerization step, the polycyclic aromatic vinyl compound can be copolymerized with the aliphatic conjugated diene compound. Examples of the aliphatic conjugated diene compound include chain conjugated diene compounds such as 1,3-butadiene and 2-methyl-1,3-butadiene (isoprene). 2-methyl-1,3-butadiene (isoprene) and 1,3-butadiene are particularly preferred because they can impart flexibility. These can be used alone or in combination of two or more.

  Here, the composition (I) may contain other compounds other than the compounds described above. Examples of such other compounds include a monocyclic aromatic vinyl compound and an unsaturated carboxylic acid ester. The monocyclic aromatic vinyl compound is a monomer unit having one aromatic hydrocarbon single ring described above. Specifically, examples of the monocyclic aromatic vinyl compound include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, and the like. Also, specifically, examples of the unsaturated carboxylic acid ester include methyl acrylate and methyl methacrylate. These can be used alone or in combination of two or more.

  The anion polymerization catalyst used in the polymerization step includes, for example, an alkyllithium compound having 1 to 10 carbon atoms in the alkyl group. When an alkyl lithium having 1 to 10 carbon atoms in the alkyl group is used as the anion polymerization catalyst, if a sulfur substance is present in the composition (I), the alkyl lithium acts as a base and the anion polymerization is inhibited. It is estimated that. Therefore, by removing at least a part of free sulfur and sulfur contained in the monomer composition by the purification method of the present invention, alkyl lithium having 1 to 10 carbon atoms in the alkyl group is used as an anion polymerization catalyst. In this case, the inhibition of the anionic polymerization reaction can be effectively suppressed.

  Examples of the alkyl lithium compound include methyl lithium, ethyl lithium, pentyl lithium, n-butyl lithium, sec-butyl lithium, t-butyl lithium, and the like. Especially, it is preferable to use n-butyllithium as an anionic polymerization catalyst from a viewpoint of making a polymerization reaction progress efficiently. The amount of the anion polymerization catalyst used may be appropriately adjusted according to the molecular weight of the target copolymer. For example, the molar equivalent of the monomer in the composition (I) to the anion polymerization catalyst is 50 equivalents. It can be in the range of not less than 3000 equivalents, more preferably in the range of not less than 100 equivalents and not more than 1400 equivalents. In addition, a known cocatalyst such as dibutyl ether may be optionally used together with the anionic polymerization catalyst.

  Further, the organic solvent used in the polymerization step is not particularly limited, and examples thereof include aliphatic hydrocarbons such as pentane, hexane, and heptane; cyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, trimethylcyclohexane, and ethylcyclohexane. , Diethylcyclohexane, decahydronaphthalene, bicycloheptane, alicyclic hydrocarbons such as tricyclodecane, hexahydroindene and cyclooctane; aromatic hydrocarbons such as benzene, toluene and xylene; dichloromethane, chloroform, 1,2-dichloroethane Halogen-based aromatic hydrocarbons such as chlorobenzene and dichlorobenzene; nitrogen-containing hydrocarbon-based solvents such as nitromethane, nitrobenzene and acetonitrile; or a mixture thereof Medium, and the like. Especially, it is preferable to use toluene as an organic solvent from a viewpoint of making a polymerization reaction progress efficiently. One of these organic solvents may be used alone, or two or more thereof may be used in combination at an arbitrary ratio. The amount of the organic solvent used can be, for example, 20 parts by mass or more and 20,000 parts by mass or less, based on 100 parts by mass of the total mass of the monomers in the composition (I).

  Examples of a method of copolymerizing the polycyclic aromatic vinyl compound and the aliphatic conjugated diene compound include a method of random copolymerization and a method of block copolymerization.

  Here, the method for randomly polymerizing the polycyclic aromatic vinyl compound and the aliphatic conjugated diene compound is not particularly limited, and a conventionally known method for producing a random copolymer can be employed. When a polycyclic aromatic vinyl compound and an aliphatic conjugated diene compound are randomly polymerized, the polycyclic aromatic vinyl compound is used as a purified monomer composition obtained according to the purification method of the present invention, thereby increasing A random polymer can be formed at a polymerization conversion. Furthermore, in the case where the polycyclic aromatic vinyl compound and the aliphatic conjugated diene compound are randomly polymerized, the content of the polycyclic aromatic vinyl compound in the composition (I) is determined based on the total amount of the monomer in the composition (I). Assuming that the body is 100% by mass, for example, it may be 5% by mass or more and 99% by mass or less. In particular, when the content of the polycyclic aromatic vinyl compound in the composition (I) is equal to or more than the above lower limit, the purified monomer composition obtained according to the purification method of the present invention is used, The conversion can be significantly increased.

The method of block copolymerizing the polycyclic aromatic vinyl compound and the aliphatic conjugated diene compound is not particularly limited, and a conventionally known method for producing a block copolymer can be employed. For example, a polymer block [A] containing a structural unit derived from a polycyclic aromatic vinyl compound and containing a structural unit derived from an aromatic vinyl compound as a main component (hereinafter, also simply referred to as “predetermined polymer block [A]”) ) And a polymer block [B] having a structural unit derived from an aliphatic conjugated diene compound as a main component (hereinafter, simply referred to as “predetermined polymer block [B]”). In the case of producing a [B]-[A]) type triblock copolymer,
(I) a first polymerization step of polymerizing a monomer mixture (a1) containing a polycyclic aromatic vinyl compound to form a predetermined polymer block [A]; and a simple polymerization step containing an aliphatic conjugated diene compound. A second polymerization step of polymerizing the monomer mixture (b1) to form a predetermined polymer block [B], and polymerizing a monomer mixture (a2) containing a polycyclic aromatic vinyl compound, A third polymerization step of forming a predetermined polymer block [A]; and (ii) a monomer mixture (a1) containing a polycyclic aromatic vinyl compound is polymerized to obtain a predetermined polymer. A polymer having a structural unit derived from an aliphatic conjugated diene compound as a main component by polymerizing a monomer mixture (b1) containing an aliphatic conjugated diene compound in a first polymerization step for forming a block [A] A second polymerization step for forming block [B ']; Coupling the ends of the polymer block [B '] with a coupling agent.
And the like. The coupling agent used in the method (ii) is not particularly limited, and a conventionally known coupling agent can be used. Further, the amount of the coupling agent to be used may be appropriately adjusted according to the molecular weight of the target block copolymer. In addition, in this specification, "the main unit" is a structural unit in which a certain polymer block is present, assuming that all the units constituting the polymer block are 100% by mass and the ratio of the certain structural unit is 50% by mass. It means that it is over, preferably 60% by mass or more, more preferably 70% by mass or more, and still more preferably 80% by mass or more. When a certain polymer block has a certain structural unit as “main component”, all the units of the polymer block may be a certain structural unit. That is, a certain polymer block may be a block consisting only of a structural unit that is a main component. The mass ratio between the compounds in the monomer mixture used to form such a polymer block conforms to the ratio of each structural unit in the target polymer block.

  In addition, the monomer mixture (a1) containing the polycyclic aromatic vinyl compound may contain a monocyclic aromatic vinyl compound, and the aromatic mixture composed of the polycyclic aromatic vinyl compound and the monocyclic aromatic vinyl compound may be used. The content of the vinyl group compound is preferably more than 50% by mass, more preferably 60% by mass or more, with the total amount of monomers contained in the monomer mixture (a1) being 100% by mass. , 70% by mass or more, more preferably 80% by mass or more. Note that all of the monomers contained in the monomer mixture (a1) may be aromatic vinyl compounds. Furthermore, the ratio of the polycyclic aromatic vinyl compound and the monocyclic aromatic vinyl compound in the monomer mixture (a1) is, based on mass, polycyclic aromatic vinyl compound: monocyclic aromatic vinyl compound = 5: 95 to It may be in the range of 100: 0. The ratio of various monomer units in the polymer block [A] obtained by polymerizing the monomer mixture (a1) also becomes a ratio according to the content and the ratio.

  The polymerization temperature is not particularly limited, and may be, for example, 20 ° C. or more and 150 ° C. or less, and preferably 25 ° C. or more and 120 ° C. or less. If the polymerization temperature is equal to or higher than the lower limit, the polymerization catalyst can function sufficiently. Further, when the polymerization temperature is equal to or lower than the upper limit, the decomposition of the polymerization catalyst can be suppressed.

  The polymerization time is not particularly limited, and may be, for example, 1 hour or more and 10 hours or less. If the polymerization time is equal to or longer than the lower limit, the polymerization reaction can proceed sufficiently. Further, when the polymerization time is equal to or less than the above upper limit, the time required for producing the copolymer can be reduced.

  After the completion of the polymerization step, the method for recovering the obtained copolymer is not particularly limited. For example, the copolymer can be recovered as it is as a polymerization solution. In addition, the reaction mixture obtained by the polymerization step can usually contain a copolymer and an organic solvent.

  Using the purified monomer composition, the polymer obtained by the polymerization step contains a structural unit derived from a polycyclic aromatic vinyl compound, and optionally, a structural unit derived from an aliphatic conjugated diene compound, and other And a structural unit derived from the compound of formula (I). More specifically, the polymer obtained by the above polymerization step is a homopolymer composed of only a structural unit derived from a polycyclic aromatic vinyl compound, or a structural unit derived from an aliphatic conjugated diene compound, and any other May be a random copolymer or a block copolymer which may contain a structural unit derived from the compound of the formula (1). Such a polymer has a narrower molecular weight distribution than a polymer polymerized according to a conventional method without using a purified monomer composition. Therefore, according to the method for producing a polymer of the present invention, a polymer having a relatively uniform molecular weight can be obtained. The “molecular weight distribution” can be measured by the method described in Examples.

  Above all, the block copolymer present in the reaction mixture obtained by performing the block copolymerization in the above polymerization step is a triblock having a ([A]-[B]-[A]) type triblock structure. When it is a block copolymer, the purity is preferably 45% or more. Such a block copolymer can be suitably used when producing a material for forming an optical component. The “purity of the triblock copolymer” can be calculated by the method described in Examples as a ratio of the mass of the triblock copolymer to the total mass of the formed block copolymer.

  The purity of the triblock copolymer is preferably at least 70%, more preferably at least 90%. When the purity of the triblock copolymer is equal to or higher than the lower limit, when a material containing such a copolymer is formed into a film, optical performance such as three-dimensional retardation can be more excellently exhibited. .

  Further, the block copolymer present in the reaction mixture obtained by performing the block copolymerization in the above polymerization step is a triblock having a ([A]-[B]-[A]) type triblock structure. In the case of a block copolymer, the molecular weight distribution is preferably 1.50 or less. Such a block copolymer can be suitably used when producing a material for forming an optical component.

  The molecular weight distribution of the triblock copolymer is preferably 2.0 or less, more preferably 1.50 or less. When the molecular weight distribution of the obtained triblock copolymer is equal to or less than the above upper limit, when a material containing such a copolymer is formed into a film, optical properties such as three-dimensional retardation are more excellently exhibited. be able to.

  Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. In the following description, “%” and “parts” representing amounts are based on mass unless otherwise specified. The methods for measuring various physical properties are described below.

<Number average molecular weight (Mn), weight average molecular weight (Mw), peak top molecular weight (Mp), and molecular weight distribution (Mw / Mn)>
Using a gel permeation chromatography (GPC), the number average molecular weight (Mn), the weight average molecular weight (Mw), and the peak top molecular weight (Mp) of each of the polymers obtained in Examples and Comparative Examples were measured, and the molecular weight was measured. The distribution (Mw / Mn) was calculated.
At that time, HLC-8320 (manufactured by Tosoh Corporation) was used as a measuring instrument. As columns, two TSKgel α-M (manufactured by Tosoh Corporation) were used in series. A differential refractometer RI-8320 (manufactured by Tosoh Corporation) was used as a detector. Then, using tetrahydrofuran as a developing solvent, the number average molecular weight (Mn), the weight average molecular weight (Mw), and the peak top molecular weight (Mp) of the above various polymers were determined as standard polystyrene equivalent values. Then, the molecular weight distribution (Mw / Mn) was calculated.

<Conversion rate>
By measuring ¹ H-NMR using deuterated chloroform as a solvent, the conversion of 2-vinylnaphthalene and the conversion of isoprene were calculated and evaluated according to the following criteria.
A: 90% or more B: 80% or more and less than 90% C: less than 80%

<Measurement of sulfur content and bromine content>
The purified monomer compositions obtained in Examples and Comparative Examples were distilled under reduced pressure to remove the solvent, and samples were obtained. About 0.02 g of a sample was weighed on a magnetic board, burned by an automatic combustion apparatus (manufactured by Yanaco), and then subjected to ion chromatography (manufactured by DIONEX, ICS-1500) to quantify the amount of sulfur and the amount of bromine. The sulfur amount and the bromine amount are based on the sulfur amount (μg) and the bromine amount (μg) contained per 1 g of the mass of the polycyclic aromatic vinyl compound, that is, the mass of the polycyclic aromatic vinyl compound. It was quantified as the amount (ppm).
The sulfur content ratio before purification and the bromine content ratio before purification were determined by dividing the respective amounts (ppm) in the purified monomer composition determined according to the above by the sulfur content in the monomer composition before purification. (Ppm) and the amount of bromine (ppm), respectively, to obtain 100 fractions.

<Purity of triblock copolymer>
The purity of the triblock copolymers obtained in Examples 8 to 10 and Comparative Examples 3 and 4 was calculated based on the following formula.
Purity (%) of triblock copolymer = [mass (g) of isolated triblock copolymer / mass (g) of total polymer contained in reaction mixture] × 100
In addition, the mass of each polymer contained in the reaction mixture was calculated based on the area ratio by gel permeation chromatography (GPC).

(Example 1)
<Sulfur removal step and halogen removal step>
In a pressure-resistant glass container, 28 g of a monomer composition (powder, sulfur content: 150 ppm, bromine content: 300 ppm, based on 2-vinylnaphthalene) containing 2-vinylnaphthalene as a polycyclic aromatic vinyl compound is weighed, and toluene is placed. Dissolved in 84 g. Thereafter, 14 g of molecular sieves 3A as a desiccant and activated alumina (NKHD-24HD, manufactured by Sumitomo Chemical Co., Ltd.) as an adsorbent were added, respectively, and the mixture was allowed to stand at 25 ° C. for 7 days. The molecular sieve 3A is a desiccant that does not contribute to the removal of sulfur and halogen and is added for the purpose of absorbing and removing water molecules in the monomer composition.
<Polymerization step>
After drying in a nitrogen atmosphere and replacing the atmosphere in the reactor with nitrogen gas, 30 ml of toluene as a solvent and 32 μl of a 1.6 M hexane solution of n-butyllithium as an anion polymerization catalyst (n-butyllithium) were used. : 52 μmol). Thereafter, 8 g of a 25% by mass toluene solution of 2-vinylnaphthalene, which is a purified monomer composition obtained in the <Sulfur removal step and halogen removal step> and subjected to a purification treatment for 7 days, is placed in the pressure-resistant reactor. (250 equivalents to n-butyllithium). After reacting at 25 ° C. for 1 hour, a part of the obtained homopolymer composed of 2-vinylnaphthalene units was collected, and various measurements and evaluations were performed as described above. Table 1 shows the results.

(Examples 2-3)
Various operations, measurements, and evaluations were performed in the same manner as in Example 1 except that the treatment periods in the <sulfur removal step and the halogen removal step> were changed as shown in Table 1. Table 1 shows the results.

(Example 4)
The treatment period in the <sulfur removal step and halogen removal step> was set to 21 days, and the amount of a 25% by mass toluene solution of 2-vinylnaphthalene, which is a purified monomer composition added in the <polymerization step>, was 16 g. Various operations, measurements, and evaluations were performed in the same manner as in Example 1 except that the amount was changed to (500 equivalents with respect to n-butyllithium). Table 1 shows the results.

(Example 5)
4 g of a 25% by mass toluene solution of 2-vinylnaphthalene obtained by the same <sulfur removal step and halogen removal step> as in Examples 3 and 4 and purified for 21 days (125 equivalents to butyllithium), 4 g of a 25 wt% toluene solution of 1-vinylnaphthalene (125 equivalents to butyllithium) purified by performing the same treatment as in purifying the monomer composition containing 2-vinylnaphthalene in Example 1. The mixed solution was used as a purified monomer composition. Except for this point, various operations, measurements and evaluations were performed in the same manner as in Example 1. Table 1 shows the results.
<Sulfur removal step and halogen removal step for 1-vinylnaphthalene>
Using a monomer composition containing 1-vinylnaphthalene as a polycyclic aromatic vinyl compound (liquid, sulfur content: 70 ppm, bromine content: <10 ppm, 1-vinylnaphthalene standard), the treatment period was set to 21 days. Except for the above, a monomer composition containing 1-vinylnaphthalene was purified in the same manner as in Example 1.

(Example 6)
The treatment period in the <sulfur removal step and the halogen removal step> is set to 28 days, and the amount of a 25% by mass toluene solution of 2-vinylnaphthalene, which is a purified monomer composition added in the <polymerization step>, is 48 g. (Various operations, measurements, and evaluations were performed in the same manner as in Example 1 except that the amount was changed to 1500 equivalents relative to n-butyllithium). Table 1 shows the results.

(Example 7)
The treatment period in the <sulfur removal step and the halogen removal step> was set to 21 days, and in the <polymerization step>, a 25% by mass toluene solution of 2-vinylnaphthalene, which was a purified monomer composition, was added to an aliphatic solution. 2 g (567 equivalents to n-butyllithium) of isoprene, a conjugated diene compound, was added. Further, the reaction temperature in the <polymerization step> was changed to 50 ° C. Thus, in this example, a random copolymer having 2-vinylnaphthalene units and isoprene units was obtained. Except for these points, various operations, measurements and evaluations were performed in the same manner as in Example 1. Table 1 shows the results.

(Comparative Example 1)
Without performing the <sulfur removal step and the halogen removal step>, the following pretreatment is performed to obtain a pretreated monomer composition (25 wt% 2-vinylnaphthalene solution in toluene). Various operations, measurements and evaluations were carried out in the same manner as in Example 1 except that a pretreated monomer composition was used instead of the purified monomer composition. Table 1 shows the results.
<Preparation process>
The same operation as in <Sulfur removal step and halogen removal step> of Example 1 was performed except that activated alumina was not used. That is, in this pretreatment step, molecular sieves 3A were added, and the mixture was allowed to stand for 7 days to remove water from the monomer composition and dried to obtain a pretreated monomer composition.

(Comparative Example 2)
In the <polymerization step>, instead of the purified monomer composition, 8 g of the undertreated monomer composition (25 wt% 2-vinylnaphthalene solution in toluene) obtained in the same manner as in Comparative Example 1 and an aliphatic 2 g of isoprene (567 equivalents to n-butyllithium), which is a conjugated diene compound, were added. Further, the reaction temperature in the <polymerization step> was changed to 50 degrees. Thus, in this comparative example, a random copolymer having a 2-vinylnaphthalene unit and an isoprene unit was obtained. Except for these points, various operations, measurements and evaluations were performed in the same manner as in Example 1. Table 1 shows the results.

  In the table, "VN" indicates vinylnaphthalene, and "IP" indicates isoprene.

  As is clear from Table 1, as in Examples 1 to 7, the purified monomer composition obtained according to the purification method including the sulfur removal step of removing sulfur from the monomer composition, It can be seen that the polymerization conversion of is high. Moreover, when the sulfur removal step was not performed as in Comparative Examples 1 and 2, it can be seen that the polymerization conversion of the monomer composition was low. In particular, as is apparent from a comparison between Examples 1 and 2 and Example 3, when the amount of sulfur contained in the monomer composition was reduced to less than 100 ppm by the sulfur removal step, a high molecular weight of 20,000 or more was obtained. It can be seen that a polymer having a high molecular weight could be obtained at a high polymerization conversion.

(Example 8)
<Manufacturing process of block copolymer>
<< First polymerization step >>
Under a nitrogen atmosphere, into a pressure-resistant reactor which was dried and replaced with nitrogen, 20 ml of toluene as an organic solvent and 32 μl of a 1.6 M hexane solution of n-butyllithium (n-butyllithium: 52 μmol) as a polymerization catalyst were respectively charged. . Then, in the above pressure-resistant reactor, 2-vinylnaphthalene, which is a purified monomer composition obtained through the same <sulfur removal step and halogen removal step> as in Example 1 as a polycyclic aromatic vinyl compound, 8 g of a 25% toluene solution (250 equivalents based on n-butyllithium) was added and reacted at 25 ° C. for 1 hour to perform a first-stage polymerization reaction to obtain a polymer. For the obtained polymer, the number average molecular weight (Mn), the weight average molecular weight (Mw), the peak top molecular weight (Mp), and the molecular weight distribution (Mw / Mn) were measured as described above. Conversion was measured and evaluated as described above. Table 2 shows the results.

<< second polymerization step >>
After the completion of the first-stage polymerization reaction, 2 g of isoprene (567 equivalents to n-butyllithium) as a chain conjugated diene compound was added to the reaction mixture in the pressure-resistant reactor, and the mixture was further heated at 50 ° C. for 30 minutes. The reaction was carried out for 2 minutes, and a second stage polymerization reaction was carried out. As a result, a diblock copolymer having a block configuration of [2-vinylnaphthalene block]-[isoprene block] was obtained in the reaction mixture. The number average molecular weight (Mn), weight average molecular weight (Mw), peak top molecular weight (Mp), and molecular weight distribution (Mw / Mn) of the obtained diblock copolymer were measured as described above. Further, the conversion of isoprene added in this step was measured and evaluated as described above. Table 2 shows the results. From the ¹ H-NMR measurement results, it was confirmed that all the 2-vinylnaphthalene remaining after the first-stage polymerization reaction was consumed.

<<< 3rd polymerization process >>
After that, the reaction mixture was further converted into an aromatic vinyl compound, 25-vinylnaphthalene, a purified monomer composition obtained through the same <sulfur removing step and halogen removing step> as in Example 1. Of toluene solution (250 equivalents based on n-butyllithium) and 8.7 μL of dibutyl ether (1 equivalent based on n-butyllithium) as a cocatalyst, and reacted at 25 ° C. for 17 hours. A third stage polymerization reaction was performed. After the completion of the polymerization reaction, 50 μL of methanol was added to stop the polymerization reaction. As a result, a triblock copolymer having a block configuration of [2-vinylnaphthalene block]-[isoprene block]-[2-vinylnaphthalene block] was obtained in the reaction mixture. The number average molecular weight (Mn), weight average molecular weight (Mw), peak top molecular weight (Mp), and molecular weight distribution (Mw / Mn) of the obtained triblock copolymer, and the purity of the triblock copolymer were determined as described above. It was measured. In addition, the conversion of 2-vinylnaphthalene added in this step was measured as described above. In addition, from the ¹ H-NMR measurement results, it was confirmed that all the isoprene remaining after the second-stage polymerization reaction was consumed.

(Example 9)
In producing the block copolymer, in the << first polymerization step >> and the << third polymerization step >>, as the polycyclic aromatic vinyl compound, the same <sulfur removal step and Halogen removal step> except that 8 g of a 25% toluene solution of 2-vinylnaphthalene (250 equivalents to n-butyllithium) which is a purified monomer composition obtained through the purification treatment for 14 days obtained through the halogen removal step> was added. In the same manner as in Example 8, various operations, measurements, and evaluations were performed. Table 2 shows the results. In addition, similarly to Example 8, at the time of completion of the second polymerization step, it was confirmed that all the 2-vinylnaphthalene remaining after the first-stage polymerization reaction was consumed, and at the time of completion of the third polymerization step. It was confirmed that all the isoprene remaining after the second-stage polymerization reaction was consumed.

(Example 10)
In producing the block copolymer, in the << first polymerization step >> and << third polymerization step >>, as the polycyclic aromatic vinyl compound, the same <sulfur removal step and Halogen removal step> except that 8 g of a 25% toluene solution of 2-vinylnaphthalene (250 equivalents to n-butyllithium) which is a purified monomer composition obtained through the purification treatment for 21 days obtained through the halogen removal step was added. In the same manner as in Example 8, various operations, measurements, and evaluations were performed. Table 2 shows the results. In addition, similarly to Example 8, at the time of completion of the second polymerization step, it was confirmed that all the 2-vinylnaphthalene remaining after the first-stage polymerization reaction was consumed, and at the time of completion of the third polymerization step. It was confirmed that all the isoprene remaining after the second-stage polymerization reaction was consumed.

(Comparative Example 3)
In producing the block copolymer, in <<< first polymerization step >>, as a polycyclic aromatic vinyl compound, an undertreated single unit obtained through the same <undertreatment step> as in Comparative Example 1 An attempt was made to sequentially perform various operations in the same manner as in Example 8 except that 8 g of a 25% toluene solution of 2-vinylnaphthalene (250 equivalents to n-butyllithium) as a body composition was added. In the second polymerization step, the conversion was less than 5%, and the reaction could not proceed further. Table 2 shows the results of the measurement and evaluation performed in the possible range.

(Comparative Example 4)
In producing the block copolymer, in the << first polymerization step >>, a monomer composition (powder containing 2-vinylnaphthalene as a polycyclic aromatic vinyl compound as a polycyclic aromatic vinyl compound) Body, sulfur content: 500 ppm, bromine content: less than 20 ppm, based on 2-vinylnaphthalene), which is a lower-treated monomer composition obtained by performing the same <lower-treatment step> as in Comparative Example 1. Various operations were attempted in the same manner as in Example 8 except that 8 g of a 25% toluene solution of vinylnaphthalene (250 equivalents to n-butyllithium) was added. As a result, the conversion was less than 5%, and the reaction could not proceed further. Table 2 shows the results of the measurement and evaluation performed in the possible range.

  In the table, "VN" indicates vinylnaphthalene, and "IP" indicates isoprene.

  From Table 2, in Examples 8 to 10, the purified monomer composition obtained through a purification method including a sulfur removal step of removing sulfur from the monomer composition was used to obtain (2-VN)- When a (IP)-(2-VN) type, that is, a triblock copolymer having a ([A]-[B]-[A]) type triblock structure is formed, a high polymerization conversion is achieved. It turns out that we could do it. On the other hand, when the sulfur removal step was not performed as in Comparative Examples 3 and 4, it can be seen that the polymerization conversion of the monomer composition was low. Furthermore, in Examples 9 to 10, it can be seen that a higher purity of the triblock copolymer could be achieved by changing the conditions such as the sulfur removal step.

According to the present invention, a monomer composition containing a polycyclic aromatic vinyl compound, which can remove at least a part of impurities which may inhibit a polymerization reaction, A purification method can be provided.
Further, according to the present invention, it is possible to provide a method for producing a polymer using a composition containing at least a purified polycyclic aromatic vinyl compound-containing monomer composition.

Claims (11)

A method for purifying a monomer composition containing a polycyclic aromatic vinyl compound having at least two monocycles selected from the group consisting of an aromatic hydrocarbon monocycle and an aromatic heteromonocycle,
Including a sulfur removal step of removing sulfur from the monomer composition,
A method for purifying a monomer composition.   In the sulfur removal step, the amount of sulfur contained in the monomer composition is 150 ppm or less based on the mass of the polycyclic aromatic vinyl compound, the monomer composition according to claim 1, Purification method.   2. The amount of sulfur contained in the sulfur-free monomer composition obtained through the sulfur removal step is set to 90% by mass or less of the amount of sulfur contained in the monomer composition before purification. Or a method for purifying a monomer composition according to item 2.   The method for purifying a monomer composition according to claim 1, further comprising a halogen removing step of removing halogen from the monomer composition.   In the halogen removing step, the amount of halogen contained in the monomer composition is set to 300 ppm or less based on the mass of the polycyclic aromatic vinyl compound, Purification method.   The amount of halogen contained in the halogen-free monomer composition obtained through the halogen removing step is 90% by mass or less of the amount of halogen contained in the monomer composition before purification. Or a method for purifying a monomer composition according to item 5.   The method for purifying a monomer composition according to any one of claims 1 to 6, wherein the polycyclic aromatic vinyl compound contains vinyl naphthalene.   A polymerization step of anionically polymerizing the composition (I) containing the purified monomer composition obtained according to the method for purifying a monomer composition according to claim 1 to obtain a polymer. , A method for producing a polymer.   The method for producing a polymer according to claim 8, further comprising copolymerizing the polycyclic aromatic vinyl compound with an aliphatic conjugated diene compound in the polymerization step.   The polymer production according to claim 9, further comprising, in the polymerization step, performing block copolymerization of the polycyclic aromatic vinyl compound and the aliphatic conjugated diene compound to obtain a block copolymer. Method.   The method for producing a polymer according to claim 9, further comprising, in the polymerization step, random-copolymerizing the polycyclic aromatic vinyl compound with an aliphatic conjugated diene compound to obtain a random copolymer.