JP2007217557A - Method for purifying polymerization solvent and polymerization method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for purifying a polymerization solvent, by which a precise anion polymerization can be performed in the polymerization solvent only by the simple treatment of the polymerization solvent containing oxygen and impurities having active hydrogen-containing groups such as hydroxyl groups, amino groups and carboxyl groups, and to provide an anion polymerization method using the purification method. <P>SOLUTION: This method for purifying the solvent is characterized by adding an organic alkali metal to the solvent containing an aromatic compound not inhibiting the polymerization reaction, until the solvent is colored, and then stirring or leaving the mixture for a prescribed time at a temperature lower by ≥-10°C than the boiling point of the polymerization solvent, and the anion polymerization method using the method. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for purifying an anionic polymerization solvent and a method for producing a polymer using the solvent, and more specifically, a compound that inhibits anionic polymerization contained in a solvent is easily detoxified and detoxified. The present invention relates to a method for producing an anionic polymer which is polymerized using a solvent.

  In anionic polymerization systems, compounds containing active hydrogen such as hydroxyl groups, amino groups, and carboxyl groups, and oxygen become polymerization inhibitors that deactivate the initiator and growth terminal anions, so if these compounds are present in the polymerization solvent, It is known that polymerization does not proceed and polymerization control cannot be performed well.

  In general anionic polymerization, it is common to add an initiator to a solvent and then drop the monomer dropwise. In this case, the polymerization inhibitor contained in the solvent reacts with the initiator, and the amount of initiator contained in the solvent. As a result, it becomes impossible to accurately synthesize a polymer having the intended molecular weight. At this time, if the initiator that maintains the polymerization activity interacts with the solvent and develops color, it is convenient because the polymerization inhibitor and the initiator contained in the solvent can be visually observed (see Patent Document 1).

  On the other hand, when diphenylethylene is added to the polymerization solvent and alkyllithium is gradually added thereto, the red color of diphenylhexyllithium is generated when the polymerization inhibitor disappears. Accordingly, since it can be confirmed that the purification of the solvent is completed when the color no longer disappears, it is generally used as a method for confirming the purification of the solvent. However, since diphenylhexyl lithium is quite stable in this method, once it is formed, it is difficult to deactivate it naturally so that it does not participate in polymerization. It is thought that the purification is likely to be insufficient because the amount is reduced and the color development is suppressed, and the ability to remove oxygen is considered to be small because the anion is stable. In addition, when this method is applied to the synthesis of a high molecular weight polymer, once the red color of diphenylhexyllithium is formed and disappears, the polymerization is stopped in the middle for the above reasons when a monomer or initiator is added and polymerized. There is a case.

  As a similar idea to diphenylhexyl lithium, for example, a method in which an anionic polymerization initiator is reacted with a styrenic monomer and coloring of a styryl anion is considered. Usually, in this case, the monomer is polymerized. Since it becomes an impurity at the time of polymer synthesis, it cannot be said to be a preferable method.

International Publication WO2005 / 121189

  The present invention relates to a method for purifying a polymerization solvent capable of performing precise anionic polymerization only by subjecting a polymerization solvent containing an active hydrogen-containing impurity such as a hydroxyl group, an amino group, or a carboxyl group or oxygen to a simple treatment, and the method thereof It is an object of the present invention to provide an anionic polymerization method using.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by causing a specific solvent and an organic alkali metal to be present in the polymerization solvent, and have completed the present invention.

  That is, the present invention adds (1) an organic alkali metal to a solvent containing an aromatic compound that does not inhibit the polymerization reaction until the solvent is colored, and at a temperature not lower than −10 ° C. and not higher than the boiling point of the polymerization solvent for a predetermined time. A solvent purification method characterized by stirring or standing, (2) a solvent purification method as described in (1) above, wherein the predetermined time is at least 5 minutes, and (3) a predetermined The method for purifying the solvent according to the above (1) or (2), wherein the remaining organic alkali metal is inactivated after stirring for a period of time or standing, and (4) the remaining organic alkali metal The method for purifying the solvent according to the above (3), wherein the inactivation treatment is to add an organic metal capable of forming a complex that does not inhibit the desired polymerization reaction with the remaining organic alkali metal, (5) Organic The method for purifying a solvent according to any one of the above (1) to (4), wherein potassium metal is added in an equimolar amount or more with respect to the active hydrogen contained in the polymerization solvent, The solvent according to any one of (1) to (5) above, wherein the solvent contains at least one selected from the group consisting of alcohol derivatives, alkali metal salts, and alkaline earth metal salts. A purification method, or (7) the solvent purification method according to any one of (1) to (6) above, wherein (7) the solvent is a solvent used for anionic polymerization, or (8) the above (1) To a polymerization method characterized by using a solvent purified by the method according to any one of to (7).

Conventional anionic polymerization requires strict distillation purification of the polymerization solvent. However, by using the method of the present invention, purification of the polymerization solvent becomes easy, and active hydrogen such as hydroxyl group, amino group, carboxyl group and the like can be removed. The polymerization solvent contained can be used without strict distillation purification. In addition, the purification process can be visually confirmed, and the degree of solvent purification is greatly improved as compared with conventional purification methods.
Since this method enables precise anionic polymerization, it is useful for production of a polymer having a controlled molecular weight and molecular weight distribution.

  The aromatic compound that does not inhibit anionic polymerization used in the present invention is a hydrocarbon-based aromatic compound that may have an ether bond structure such as a methoxy group, a 2-methoxyethyl group, and a benzyloxy group. Benzene, toluene, xylene, mesitylene, ethylbenzene, naphthalene, 1-methylnaphthalene, anthracene, 9-methylanthracene, anisole, phenylbenzyl ether, 2-methoxyethylbenzene, diphenyl ether, 1-methoxynaphthalene, 1-methoxyanthracene, etc. These are C4 to C24 hydrocarbon-based aromatic compounds.

  The amount of the aromatic compound used is not limited as long as the amount of the organic compound is colored at 0 ° C. or more and the boiling point of the polymerization solvent when the organic alkali metal is added, but the aromatic compound occupies the polymerization solvent. The amount of the compound is preferably 0.1% by weight or more. Moreover, when the organic alkali metal is added, the time during which the organic alkali metal is kept active can be controlled by the amount of the aromatic compound in the polymerization solvent. As the amount of the aromatic compound increases, the time during which the organic alkali metal remains active becomes longer, so that the convenience of the desired production process can be easily satisfied.

  The organic alkali metal used in the present invention is ethyl lithium, n-butyl lithium, sec-butyl lithium, t-butyl lithium, ethyl sodium, lithium biphenyl, lithium naphthalene, sodium naphthalene, potassium naphthalene, α-methylstyrene naphthalene dianion, Examples include 1,4-dilithio-2-butene, 1,6-dilithiohexane, cumyl potassium, cumyl cesium and the like.

  The organometallic used in the present invention is organomagnesium, organozinc, or organoaluminum. Specifically, an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms is present on the metal atom. The metal compound to substitute can be illustrated. Specific examples of such substituents include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, s-butyl group, t-butyl group, isobutyl group, amyl group, hexyl group, and benzyl. Examples thereof include a group, a phenyl group, and a naphthyl group.

  Specific examples of the organic metal having magnesium, aluminum, or zinc as a metal species include di-n-butylmagnesium, di-t-butylmagnesium, di-s-butylmagnesium, n-butyl-s-butylmagnesium, n-butyl-ethylmagnesium, di-n-amylmagnesium, dibenzylmagnesium, diphenylmagnesium, diethylzinc, di-n-butylzinc, trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, etc. It can be illustrated.

  Each of the anionic species exemplified above can be used alone or in combination of two or more.

  The amount of the organic metal used can be arbitrarily used within a range that does not affect the polymerization, but specifically, an equimolar ratio is preferred in the molar ratio with respect to the remaining organic alkali metal. If the amount used is too small, there is a high possibility that the organic alkali metal will remain and polymerization will start, and if it is too large, the growth rate during polymerization will be reduced or the molecular weight will not be controllable. There is a case.

  The alcohol derivatives, alkali metal salts, and alkaline earth metal salts used in the present invention are specifically mineral salts and halides such as sodium, potassium sulfate, nitrate and borate, and alkalis of aliphatic alcohols. Examples include metal salts, halides, and alkaline earth metal salts of aliphatic alcohols. More specifically, lithium chloride, bromide, iodide, lithium borate, sodium chloride, potassium chloride, methanol, Alcohol derivatives such as butanol and phenol can be mentioned. Among these, lithium halides are preferable. The alkali metal salts, the alkali metal salts of alcohol derivatives and the alkaline earth metal salts of alcohol derivatives exemplified here facilitate the polymerization control, but are not preferred in the method of adding them later during the polymerization because they easily absorb moisture.

  These exemplified alcohol derivatives, alkali metal salts, and alkaline earth metal salts can be used singly or in combination of two or more.

  The anion polymerizable monomer used in the present invention is not particularly limited as long as it has an anion polymerizable unsaturated bond. Specifically, a styrene derivative, a butadiene derivative, a (meth) acrylic acid ester derivative, etc. It can be illustrated preferably. Specific examples of the styrene derivative include styrene, α-alkyl styrene, and nucleus-substituted styrene. The nucleus substituent includes an anionic species having a polymerization initiating ability and an anionic species having no ability to initiate polymerization. And is not particularly limited as long as it is an inactive group. Specifically, an alkyl group, an alkoxyalkyl group, an alkoxy group, an alkoxyalkoxy group, a t-butoxycarbonyl group, a t-butoxycarbonylmethyl group, a tetrahydropyranyl group, etc. Can be illustrated. Specific examples of the styrene derivative include α-methylstyrene, α-methyl-p-methylstyrene, p-methylstyrene, m-methylstyrene, o-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, 2 , 5-dimethylstyrene, p-isopropylstyrene, 2,4,6-triisopropylstyrene, pt-butoxystyrene, pt-butoxy-α-methylstyrene, mt-butoxystyrene, etc. Can do.

  Specific examples of the butadiene derivative include 1,3-butadiene, isoprene, 2,3-dimethylbutadiene, 2-ethyl-1,3-butadiene, 1,3-pentadiene, and the like.

  In addition, the (meth) acrylic acid ester derivative is preferably one having an ester alcohol residue having 1 to 20 carbon atoms from the viewpoint of reactivity. Specifically, methyl ester, ethyl ester, isopropyl ester, n-butyl ester, etc. Can be illustrated.

  These exemplified monomers can be used alone or in combination of two or more.

  The polymerization temperature in the present invention is not particularly limited as long as it is a temperature range in which side reactions such as transfer reaction and termination reaction do not occur and the monomer is consumed and the polymerization is completed, but it is −70 ° C. or more and the polymerization solvent boiling point or less. It is preferably performed in the temperature range. The concentration of the monomer with respect to the polymerization solvent is not particularly limited, but is usually in the range of 1 to 40% by weight, and particularly preferably in the range of 2 to 15% by weight.

  The polymerization solvent used in the present invention is preferably an ether group-containing solvent, and specific examples include ether compounds such as diethyl ether, tetrahydrofuran (THF), dioxane, and trioxane. Moreover, these solvent can be used individually by 1 type or as a 2 or more types of mixed solvent.

  Moreover, if it is a polar solvent which does not participate in a polymerization reaction and is compatible with a polymer, it will not restrict | limit, and it can use together with an ether group containing solvent. Specific examples thereof include tertiary amines such as tetramethylethylenediamine and hexamethylphosphoric triamide.

  Furthermore, even if it is an aliphatic or alicyclic hydrocarbon compound with low polarity, if it is relatively compatible with the polymer, it can be used in combination with an ether group-containing solvent. A combination of xane and THF can be exemplified.

  Since the polymer obtained by the method of the present invention has a controlled molecular weight, it becomes a monodispersed polymer with a narrow molecular weight distribution. The molecular weight dispersity (weight average molecular weight (Mw) / number average molecular weight (Mn)) of this polymer is usually 1.01 to 2.50, preferably 1.01 to 1.50.

  In the present invention, in order to more accurately define the molecular weight of the obtained polymer, after polymerizing a certain monomer, the molecular weight is grasped by GPC or the like, and further required for the desired molecular weight of the polymer. By using a multistage polymerization in which a monomer is added to adjust the molecular weight, the molecular weight can be regulated more precisely. When producing a multistage polymerization or block polymer, it is preferable to add an organic metal to the monomer to be added.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, the scope of the present invention is not limited to an Example.

  Under a nitrogen atmosphere, 1.35 g (3.3 mmol) of an n-BuLi solution was added to a mixed solvent of 180 g of THF and 20 g of toluene at room temperature to give a yellow color. The mixture was stirred in that state for 75 minutes. After confirming that the coloring disappeared, the mixture was cooled to −50 ° C., 5.72 g (54.9 mmol) of styrene was added, and the mixture was stirred for 10 minutes. Thereafter, 0.38 g (0.3 mmol) of an n-BuLi / diethyl zinc ate complex solution was added and stirred for 7 minutes. Subsequently, 0.17 g (0.4 mmol) of n-BuLi solution was added and stirred for 10 minutes, and methanol was added to kill. When this killing solution was measured by gas chromatography, no monomer remained. Further, when GPC measurement was performed, a polymer having a molecular weight (Mw) of 37800 and a dispersion degree of 1.14 was produced.

  Under a nitrogen atmosphere, 0.12 g (1.0 mmol) of 2-mercaptothiazoline was added to a mixed solvent of 180 g of THF and 20 g of toluene, and 0.92 g (2.2 mmol) of an n-BuLi solution was added at room temperature to give a yellow color. Therefore, it stirred for 60 minutes in the state. Thereafter, the system was cooled to −50 ° C., and 0.23 g (0.3 mmol) of diethylzinc solution was added, and the color of the system disappeared. Subsequently, 4.92 g (47.2 mmol) of styrene was added, 0.15 g (0.05 mmol) of a hexane-diluted n-BuLi solution was added, stirred for 30 minutes, and methanol was added to kill. When this killing solution was measured by gas chromatography, no monomer remained. Further, when GPC measurement was performed, a polymer having a molecular weight (Mw) of 163200 and a dispersity of 1.18 was produced.

Under a nitrogen atmosphere, 0.91 g (2.2 mmol) of an n-BuLi solution was added to a mixed solvent of 180 g of THF and 20 g of toluene at room temperature to give a yellow color, and the mixture was stirred for 65 minutes in that state. Thereafter, the system was cooled to −50 ° C., and the system was a pale lemon color, but 3.60 g (34.6 mmol) of styrene was added and stirred for 5 minutes, 0.0.13 g (0.3 mmol) of n-BuLi solution. And methanol was added to kill. When this killing solution was measured by gas chromatography, no monomer remained. Further, when GPC measurement was performed, a polymer having a molecular weight (Mw) of 20500 and a dispersion degree of 1.06 was produced.

Claims (8)

  An organic alkali metal is added to a solvent containing an aromatic compound that does not inhibit the polymerization reaction until the solvent is colored, and the mixture is stirred or left standing at a temperature of −10 ° C. or higher and lower than the boiling point of the polymerization solvent for a predetermined time. To purify the solvent.   2. The method for purifying a solvent according to claim 1, wherein the predetermined time is at least 5 minutes.   The method for purifying a solvent according to claim 1 or 2, wherein the remaining organic alkali metal is inactivated after being stirred or allowed to stand for a predetermined time.   4. The solvent according to claim 3, wherein the inactivation treatment of the remaining organic alkali metal is adding an organic metal capable of forming a complex that does not inhibit the desired polymerization reaction with the remaining organic alkali metal. Purification method.   The method for purifying a solvent according to any one of claims 1 to 4, wherein the organic alkali metal is added in an equimolar amount or more with respect to the active hydrogen contained in the polymerization solvent.   The solvent is a solvent containing at least one selected from the group consisting of alcohol derivatives, alkali metal salts, and alkaline earth metal salts, purification of the solvent according to any one of claims 1 to 5 Method.   The solvent purification method according to claim 1, wherein the solvent is a solvent used for anionic polymerization. A polymerization method using the solvent purified by the method according to claim 1.