JPH07109310A - Method for purifying cyclic olefinic polymer - Google Patents

Abstract

PURPOSE:To obtain a polymer, sufficiently freed of a catalyst residue containing a metal or other impurities and capable of manifesting high transparency by adding an oxidizing agent and/or a basic compound to a cyclic olefinic polymer solution and extracting and removing the impurities with a poor solvent. CONSTITUTION:This method for purifying a cyclic olefinic polymer is to carry out a step for adding an oxidizing agent to a polymer solution of the cyclic olefinic polymer produced by the ring opening polymerization using a catalyst containing a metallic element and extracting impurities with a poor solvent and/or a step for adding a basic compound to the polymer solution and extracting and removing the impurities with the poor solvent. Cerium chloride, ferric chloride, etc., are used as the oxidizing agent and lower alkyl ketones or lower alcohols are preferred as the poor solvent. Hydrochloric acid, etc., together with the oxidizing agent are preferably added to the polymer solution. The solution of the polymer is prepared in toluene, xylene, etc., as a good solvent. Sodium hydroxide, potassium hydroxide, etc., are used as the basic compound.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for purifying a cyclic olefin polymer produced by ring-opening polymerization using a catalyst containing a metal element.

[0002]

2. Description of the Related Art Among cyclic olefin polymers, specific cyclic olefin polymers such as (co) polymers of norbornene derivatives and hydrogenated polymers thereof are useful as resins having excellent optical properties. Although various cyclic olefin polymers and methods for producing them have been proposed, a method using a metacis catalyst is particularly advantageous. Therefore, in order to obtain the optical characteristics required as an optical material in these cyclic olefin-based polymers, the metal compound components, unreacted monomers, and the like contained in the cyclic olefin-based polymer are low. It is required to control the content of molecular weight substances and other impurities to an extremely low level. In order to meet this demand, conventionally, by adding a polymer solution of a cyclic olefin polymer into a large amount of a poor solvent to cause precipitation of the polymer, or by further washing this precipitate with a poor solvent, A method of performing a purification treatment for removing a metal compound component derived from a metacis catalyst, a low molecular weight substance, and the like, and then drying it to obtain a target polymer has been performed.

However, in such a method, in order to carry out purification by precipitation and washing of the polymer,
It requires a large amount of antisolvent equivalent to 10 times the weight of the polymer solution or more. Therefore, in the industrial implementation of the method, there is a problem that a facility for recovering the solvent becomes large in scale.

On the other hand, in Japanese Patent Laid-Open No. 22724/1990, a method is proposed in which alcohol, which is a poor solvent, is added to a polymer solution of a cyclic olefin polymer to extract and remove a metal compound component and a low molecular weight substance into an alcohol phase. Has been done.

[0005]

However, even in the above-mentioned method, it is difficult to sufficiently remove impurities such as metal compounds from the polymer solution, and the recovered polymer does not always have sufficiently high transparency. It does not have. Therefore, the polymer cannot be used as a molding material for an optical product that requires very high transparency.

[0006] The present invention provides a method for purifying a cyclic olefin polymer, which is capable of sufficiently removing impurities from a polymer solution of a cyclic olefin polymer and recovering a polymer having high transparency. The purpose is to provide.

[0007]

The present invention provides a method for purifying a cyclic olefin-based polymer produced by ring-opening polymerization using a catalyst containing a metal element, wherein a solution of the cyclic olefin-based polymer is oxidized. The method is characterized by including a step of adding an agent and extracting and removing impurities with a poor solvent, and / or adding a basic compound and extracting and removing impurities with a poor solvent.

[0008]

In the present invention, by adding an oxidizing agent to the solution of the cyclic olefin polymer, at least a part of the metal compound components such as the metal-containing catalyst residue and other impurities are in an oxide state. Since the solubility in the poor solvent is high, the impurities are highly efficiently extracted into the poor solvent phase. As a result, by separating the poor solvent phase and the good solvent phase, the polymer in which the metal compound component and other oxidizable impurities are sufficiently removed from the good solvent phase can be recovered.

Further, by adding a basic compound to the solution of the cyclic olefin polymer, the metal compound component such as a catalyst residue containing a metal and other part of other impurities are, for example, in a hydroxide state. Since the solubility in the poor solvent is high, the impurities are highly efficiently extracted into the poor solvent phase. As a result, by separating the poor solvent phase and the good solvent phase, the metal compound component that reacts with the basic compound and other impurities can be sufficiently removed from the good solvent, and a polymer with higher transparency can be recovered. it can.

Further, by passing through a step of adding an oxidizing agent to the solution of the cyclic olefin-based polymer for extraction and a step of adding a basic compound for extraction, oxidizable impurities and other components are extracted from the solution. Both impurities can be removed with extremely high efficiency, and a polymer having high transparency can be obtained.

The present invention will be specifically described below.
The cyclic olefin polymer which is the object of the purification method of the present invention is a ring-opening polymer obtained from a specific monomer described below, and specifically includes the following items. Ring-opening polymer of specific monomer Ring-opening copolymer of specific monomer and copolymerizable monomer Hydrogenated polymer of the above-mentioned ring-opening (co) polymer Specific monomer and unsaturated double bond Saturated copolymer with contained compound

<Specific Monomer> Here, the specific monomer is
It is a compound having a norbornene structure represented by the following chemical formula 1.

[0013]

[Chemical 1] (In Chemical Formula 1, R ^{1 to} R ¹² are each a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 10 carbon atoms, or another monovalent organic group, and they may be the same or different. ⁹ and R ¹⁰ or R ¹¹ and R ¹² may combine to form a divalent hydrocarbon group, and R ⁹ or R ¹⁰ and R ¹¹
Alternatively, R ¹² may combine with each other to form a monocyclic or polycyclic structure. m is 0 or a positive integer, and m is 2
In the above cases, R ^{1 to} R ⁴ may be the same or different. p is 0 or a positive integer. )

Among the specific monomers, R ⁹ in the above chemical formula 1
At least one of R ¹² to R ¹² is a polar group, especially of the formula
The specific monomer which is a specific polar group represented by H ₂ ) _n COOR ¹³ is preferable in that the hydrogenated product of the obtained ring-opening polymer has a high glass transition temperature and a low hygroscopicity.

In the above formulas relating to the particular polar group, R
¹³ is a hydrocarbon group having 1 to 12 carbon atoms. Also, n
The smaller the value of, the higher the glass transition temperature of the obtained ring-opening polymer, which is preferable. Further, the specific monomer in which n is 0 is easy to synthesize, It is preferable because the polymer has a high glass transition temperature. Further, one of R ⁹ and R ¹⁰ or one of R ¹¹ and R ¹² in the above chemical formula 1 is preferably an alkyl group, particularly a methyl group. In particular, this alkyl group has the above formula — (CH ₂ ) _n It is preferable that the specific polar group represented by COOR ¹³ is bonded to the same carbon atom as the carbon atom bonded thereto. In the above chemical formula 1, m is 1 and p is 0.
The specific monomer is more preferable in that a ring-opening polymer having a high glass transition point can be obtained.

Specific examples of the specific monomer represented by the above chemical formula 1 include bicyclo [2.2.1] hept-2-ene,
Tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, hexacyclo [6.6.1.1 ^3,6 . 0 ^2,7 .
0 ^9,14] -4-heptadecene, tricyclo [5.2.
1.0 ^2,6 ] -8-decene, pentacyclo [6.5.
1.1 ^3,6 . 0 ^2,7 . 0 ^9,14 ] -4-Hexadecene, pentacyclo [6.5.1.1 ^3,6 . 0 ^2,7 . 0 ^9,13 ]-
4-pentadecene, heptacyclo [8.7.0.
1 ^2,9 . 1 ^4,7 . 1 ^11,17 . 0 ^3,8 . 0 ^12,16 ] -5
Eicosene, pentacyclo [4.7.0.1 ^2,5 . 0
^8,13 . 1 ^9,12 ] -3-Pentadecene, tricyclo [4.
4.0.1 ^2,5 ] -3-undecene, 5-carboxymethylbicyclo [2.2.1] hept-2-ene, 5-methyl-5-carboxymethylbicyclo [2.2.1] hept- 2-ene, 5-cyanobicyclo [2.2.1] hept-2-ene, 8-carboxymethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-
Carboxyethyl tetracyclo [4.4.0.1 ^2,5 .
1 ^7,10 ] -3-dodecene, 8-carboxy n-propyl tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-Dodecene, 8-carboxyisopropyl tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,

8-carboxy n-butyl tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-
Methyl-8-carboxymethyltetracyclo [4.4.
0.1 ^2,5 . ^1,7,10 ] -3-dodecene, 8-methyl-8
-Carboxyethyltetracyclo [4.4.0.
1 ^2,5 . 1 ^7,10 ] -3-Dodecene, 8-methyl-8-carboxy n-propyl tetracyclo [4.4.0.1
^2,5 . ^1,7,10 ] -3-Dodecene, 8-methyl-8-carboxyisopropyltetracyclo [4.4.0.
1 ^2,5 . 1 ^7,10 ] -3-Dodecene, 8-methyl-8-carboxy n-butyl tetracyclo [4.4.0.
1 ^2,5 . 1 ^7,10 ] -3-Dodecene, 8-ethylidene tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-ethyltetracyclo [4.4.0.1 ^2,5 . 1
^7,10 ] -3-Dodecene, 8-methyltetracyclo [4.
4.0.1 ^2,5 . 1 ^7,10 ] -3-Dodecene, 6-ethyl-1,4,5,8-dimethano-1,4,4a, 5,6,6
7,8,8a-octahydronaphthalene, 5,10-dimethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ]-
3-dodecene,

Dimethanooctahydronaphthalene, ethyltetracyclododecene, trimethanooctahydronaphthalene, pentacyclo [8.4.0.1 ^2,5 . 1 ^9,12 . 0
^8,13 ] -3-Hexadecene, pentacyclo [7.4.
0.1 ^2,5 . 1 ^9,12 . 0 ^8,13] -3-pentadecene, heptacyclo [8.7.0.1 ^3,6. 1 ^10,17 .
1 ^12,15 . 0 ^2,7 . 0 ^{11, 16]} -4-eicosene, heptacyclo [8.8.0.1 ^4,7. 1 ^11,13 . 1 ^13,16 .
0 ^3,8 . 0 ^12,17 ] -5- ^{heneicosene and the} like can be mentioned. Of these, 8-methyl-8-carboxymethyltetracyclo [4.4.0.1 ^2,5 .
^1,7,10 ] -3-dodecene is preferable because the polymer obtained by ring-opening polymerization of this compound has a high glass transition temperature and low hygroscopicity. The above-mentioned specific monomers are not necessarily used alone, and the ring-opening copolymerization reaction can be carried out using two or more kinds.

<Copolymerizable Monomer> The cyclic olefin-based polymer may be a ring-opening polymerization product of the above-mentioned specific monomer, but it may be a copolymerizable monomer with the specific monomer. It may be a ring-opening copolymerized with a monomer. Specific examples of the copolymerizable monomer used in this case include cyclobutene, cyclopentene, cycloheptene, cyclooctene, tricyclo [5.2.1.0 ^2,6 ] -3-decene,
Cycloolefins such as 5-ethylidene-2-norbornene and dicyclopentadiene can be mentioned. Further specified in the presence of an unsaturated hydrocarbon-based polymer having a carbon-carbon double bond in the main chain such as polybutadiene, polyisoprene, styrene-butadiene copolymer, ethylene-non-conjugated diene copolymer, polynorbornene The monomer may be subjected to ring-opening polymerization. The hydrogenated product of the ring-opening copolymer obtained in this case is useful as a raw material for a resin having high impact resistance.

<Unsaturated Double Bond-Containing Compound> Further, examples of the unsaturated double bond-containing compound used together with the above-mentioned specific monomer to obtain a cyclic olefin polymer comprising a saturated copolymer include ethylene. , Propylene, butene and the like.

<Polymerization Catalyst> The ring-opening (co) polymer of the above-mentioned specific monomer is produced by a polymerization reaction carried out in the presence of a metathesis catalyst. This metathesis catalyst
(A) at least one selected from compounds of W, Mo and Re, and (b) an element of Group IA of Deming (for example, Li, Na, K, etc.), an element of Group IIA (for example, Mg,
Ca, etc., IIB group elements (eg Zn, Cd, Hg etc.), IIIA group elements (eg B, Al etc.), IVA group elements (eg Si, Sn, Pb etc.) or IVB group elements (eg Ti, Zr). Etc.) and a catalyst comprising a combination with at least one selected from those having at least one element-carbon bond or element-hydrogen bond. Further, in this case, an additive (c) described below may be added to enhance the activity of the catalyst.

Representative examples of W, Mo or Re compounds suitable as the component (a) include WCl ₆ and MoC.
Examples thereof include compounds described in JP-A-1-240517 such as l ₅ and ReOCl ₃ . (B) Specific examples of the _{component, n-C 4 H 9 Li} , (C 2 H 5) 3 Al
, (C ₂ H ₅ ) ₂ AlCl, (C ₂ H ₅ ) _1.5 AlC
l _1.5, mention may be made of _{(C 2 H 5) AlCl 2} , methylalumoxane, compounds described in JP-A 1-240517 discloses such LiH. As typical examples of the component (c) which is an additive, alcohols, aldehydes, ketones, amines and the like can be preferably used, and further, the compounds shown in JP-A-1-240517 are used. be able to.

The amount of the metathesis catalyst used is such that the molar ratio of the component (a) to the specific monomer is usually 1: 500 to 1: 50000 (component (a) component: specific monomer).
The range is preferably 1: 1000 to 1: 10000. The ratio of the component (a) to the component (b) is such that the metal atom ratio of (a) :( b) is in the range of 1: 1 to 1:50, preferably 1: 2 to 1:30. (A) component and (c)
The ratio to the components is 0.00 in terms of molar ratio of (c) :( a).
The range is 5: 1 to 15: 1, preferably 0.05: 1 to 7: 1.

Further, in the present invention, the catalyst for synthesizing the saturated copolymer of the above-mentioned specific monomer and the unsaturated double bond-containing compound is at least selected from titanium compounds, zirconium compounds and vanadium compounds. 1
A seed and an organoaluminum compound as a cocatalyst are used. The vanadium compound is represented by the general formula VO (OR) _a X _b or V (OR) _c X _d (wherein R is a hydrocarbon group, X is a halogen atom, and 0 ≦ a ≦ 3, 0 ≦ b ≦ 3, 2 ≦ a + b ≦ 3, 0 ≦ c
≦ 4, 0 ≦ d ≦ 4, 3 ≦ c + d ≦ 4. The vanadium compound represented by the above) or an electron donor adduct thereof is used. As the electron donor, alcohols, phenols, ketones, aldehydes, carboxylic acids, esters of organic acids or inorganic acids, ethers, acid amides, acid anhydrides, oxygen-containing electron donors such as alkoxysilanes, ammonia, amines, nitriles, Examples thereof include nitrogen-containing electron donors such as isocyanate.

The titanium compound may be titanium tetrachloride, titanium trichloride and the like, and the zirconium compound may be bis (cyclopentadienyl) zirconium chloride and bis (cyclopentadienyl) zirconium dichloride. .

As the organoaluminum compound, at least one selected from compounds having at least one aluminum-carbon bond or aluminum-hydrogen bond is used. In the above, for example, when a vanadium compound is used, the ratio of the vanadium compound to the organoaluminum compound is such that the ratio of aluminum atoms to vanadium atoms (Al / V) is 2 or more, preferably 2 to 50, particularly preferably 3 to 20. Is the range.

<Polymerization Reaction Solvent> For the polymerization reaction solvent used in the polymerization reaction using the above-mentioned polymerization catalyst, specifically, the solvent constituting the solution of the molecular weight regulator described below, the specific monomer and / or the catalyst solution. Examples of the solvent include pentane, hexane, heptane, octane, nonane, alkanes such as decane, cyclohexane, cycloheptane, cyclooctane, decalin, cycloalkanes such as norbornane, benzene, toluene, xylene, ethylbenzene, cumene, etc. Aromatic hydrocarbons, chlorobutane, bromhexane, methylene chloride, dichloroethane, hexamethylene dibromide, chlorobenzene, chloroform, tetrachloroethylene and other halogenated alkanes or halogenated aryls, ethyl acetate, n-butyl acetate, acetic acid i o- butyl, methyl propionate, saturated carboxylic acid esters such as dimethoxyethane, dibutyl ether, tetrahydrofuran, and the like can be illustrated ethers such as dimethoxyethane, they can be used singly or in combination. Of these, aromatic hydrocarbons are preferred. The amount of the polymerization reaction solvent used, the ratio of the solvent and the specific monomer,
The weight ratio is usually 1: 1 to 10: 1, preferably 1: 1 to 5: 1.

<Molecular Weight Controlling Agent> The molecular weight of the cyclic olefin polymer can be controlled by the polymerization temperature, the type of catalyst and the type of solvent, but normally, the molecular weight controlling agent is allowed to coexist in the reaction system. Done by here,
Examples of suitable molecular weight regulators include α-olefins such as ethylene, propene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and styrene. It is possible,
Of these, 1-butene and 1-hexene are particularly preferable. These molecular weight regulators can be used alone or in admixture of two or more. The amount of the molecular weight modifier used is 0.
The amount is 005 to 0.6 mol, preferably 0.02 to 0.5 mol. As the cyclic olefin polymer whose molecular weight is adjusted by the above-mentioned molecular weight modifier, for example, one having an intrinsic viscosity (η _inh ) in the range of 0.2 to 5.0 is preferably used.

<Hydrogenation Reaction> The ring-opening polymer obtained as described above is preferably hydrogenated using a hydrogenation catalyst. The hydrogenation reaction is a usual method,
That is, a hydrogenation catalyst is added to a polymer solution of the polymer produced by the polymerization reaction, and the hydrogenation catalyst is added thereto at atmospheric pressure to 300
Atmospheric pressure, preferably 3 to 200 atm of hydrogen gas 0 to 20
It is carried out by operating at 0 ° C, preferably 20 to 180 ° C. The hydrogenated polymer obtained by hydrogenating in this way has excellent thermal stability, and its characteristics are not deteriorated by heating during molding or during use as a product. The hydrogenation rate is usually 50% or higher, preferably 70% or higher, more preferably 90% or higher.

As the hydrogenation catalyst, those used in ordinary hydrogenation reactions of olefinic compounds can be used. Heterogeneous catalysts and homogeneous catalysts are known as the hydrogenation catalyst. Examples of the heterogeneous catalyst include solid catalysts in which a noble metal catalyst substance such as palladium, platinum, nickel, rhodium, and ruthenium is supported on a carrier such as carbon, silica, alumina, and titania. Further, as a homogeneous catalyst, nickel naphthenate / triethylaluminum, nickel acetylacetonate / triethylaluminum, cobalt octenoate / n-butyllithium, titanocene dichloride /
Diethyl aluminum monochloride, rhodium acetate, chlorotris (triphenylphosphine) rhodium, dichlorotris (triphenylphosphine) ruthenium, chlorohydrocarbonyltris (triphenylphosphine) ruthenium, dichlorocarbonyltris (triphenylphosphine) ruthenium, etc. it can. The catalyst may be in the form of powder or particles. These hydrogenation catalysts are used in such a ratio that the weight ratio of the ring-opening polymer to the hydrogenation catalyst is 1: 1 × 10 ⁻⁶ to 1: 2.

In the first purification method of the present invention, an oxidizing agent and a poor solvent are added to a solution of the cyclic olefin polymer as described above in a good solvent, and a mixing treatment is carried out by stirring or the like. Impurities are extracted by separating the poor solvent phase and the good solvent phase, and the cyclic olefin polymer is recovered from the good solvent phase.

<Good solvent> The good solvent for the solution of the cyclic olefin polymer to be subjected to the refining treatment means a concentration of 5% by weight when the cyclic olefin polymer is dissolved in a saturated state at room temperature. It means the above solvent. Specific examples thereof include the same solvents as those listed as the polymerization reaction solvent. Among these, aromatic hydrocarbons,
Ethers having a cyclic structure and saturated carboxylic acid esters are preferable as good solvents. The solution of the cyclic olefin polymer in a good solvent is a solution in which the solid cyclic olefin polymer obtained by removing the polymerization reaction solvent or the solvent in the hydrogenation reaction from the polymerization reaction solution is redissolved in a good solvent. However, when the polymerization reaction solvent or the solvent in the hydrogenation reaction is a good solvent, the polymerization reaction solution or the solution in the hydrogenation reaction may be used as it is as a solution of the cyclic olefin polymer in the good solvent. it can.

The weight ratio (polymer: good solvent) of the solution of the cycloolefin polymer to be purified is 50:50 to.
The ratio is in the range of 5:95, preferably in the range of 30:70 to 10:90, and it is preferable that the cyclic olefin polymer is completely dissolved to form a uniform polymer solution. When the good solvent used contains impurities such as peroxides, it is preferable to remove the impurities by distillation or the like.

<Oxidizing agent> As the oxidizing agent added to the solution of the cyclic olefin polymer in a good solvent, a compound of a metal element contained in the polymerization catalyst used in the production of the ring-opening polymer is used. A compound having an oxidizing effect on a compound present as an impurity in the coalescence, that is, a compound having a larger redox potential (standard electrode potential) than the compound present as an impurity is used. For example, when a compound containing W or Mo is used as the polymerization catalyst, the redox potential of W and Mo is −0.03 V, but in practice, the redox potential of the oxidant is −0.03 V.
An organic compound or an inorganic compound having a voltage of 0.2 V or higher is used. Specific examples of the oxidizing agent, cerium chloride, ferric chloride, tin tetrachloride, chloride compounds such as copper chloride, sulfate such as cerium sulfate, potassium persulfate, persulfate such as ammonium persulfate, hydrogen peroxide, Examples thereof include peroxide compounds such as benzoyl peroxide, lauroyl peroxide, cumene hydroperoxide, and oxygen. These compounds may be used alone or in combination of two or more. The amount of these oxidizing agents used is 0.0 with respect to the polymer.
It is used in the range of 001 to 10% by weight. If the amount of the oxidizing agent used is too small, the efficiency of removing impurities such as metal compounds will be poor, and if it is too large, the impurities will remain in the polymer and cause coloration, which is not preferable.

Here, it is preferable to add an acid together with an oxidizing agent to the solution of the polymer in a good solvent. <Acid> Formic acid, acetic acid, lactic acid, butyric acid, citric acid, oxalic acid, tartaric acid, which are added to the above solution together with an oxidizing agent,
Examples thereof include organic acids such as benzoic acid and toluenesulfonic acid, and inorganic acids such as hydrochloric acid and sulfuric acid. The addition amount of these organic acids or inorganic acids is 0.01 with respect to a good solvent.
It is preferable to be 10 to 10% by weight, preferably 0.1 to 5% by weight. By adding these acids together with an oxidizing agent to the above solution and performing a mixing treatment, it becomes possible to improve the efficiency of removing impurities such as metal compounds.

A poor solvent is added to and mixed with a solution of the cyclic olefin polymer in a good solvent together with the above-mentioned oxidizing agent, and thereafter, a good solvent phase and a poor solvent phase are separated. These oxidizing agents may be added to a solution of the polymer in a good solvent in advance and treated, and then mixed with a poor solvent, or the oxidizing agent and the poor solvent may be simultaneously added and mixed. It can also be processed. <Poor solvent> The poor solvent added to the solution of the cyclic olefin polymer in a good solvent has a concentration of 5 when the cyclic olefin polymer is dissolved in a saturated state at room temperature.
A solvent that is less than wt% and is immiscible with the good solvent used. Further, the poor solvent used in the present invention preferably has high miscibility with water. Specific examples of the poor solvent include lower alcohol esters of lower carboxylic acids such as methyl formate, ethyl formate, methyl acetate and ethyl acetate, lower alkyl ketones such as acetone and methyl ethyl ketone, methanol, ethanol, propanol and butanol. One selected from lower alcohols such as benzene, pentanol, and hexanol, or a mixed solvent thereof can be used. Further, an aliphatic hydrocarbon compound such as hexane, heptane, octane, nonane, decane, undecane, dodecane can be used. Of these, lower alkyl ketones and lower alcohols are particularly preferable. When the poor solvent used contains impurities, it is preferable to remove the impurities by distillation or the like.

Specific examples of the combination of a good solvent and a poor solvent which are preferred in the present invention include, as the good solvent, aromatic hydrocarbon compounds such as toluene and xylene, cyclic ether compounds such as tetrahydrofuran and dioxane, and acetic acid n-. Butyl, selected from carboxylic acid esters such as isobutyl acetate, and the poor solvent is methanol,
Examples include combinations of those selected from lower alcohols such as ethanol and propanol.

The amount of the poor solvent added is such that the weight ratio to the good solvent (good solvent: poor solvent) is in the range of 90:10 to 10:90. If the amount of the poor solvent added is too small, the extraction efficiency of impurities such as metal compounds decreases, while if the amount of the poor solvent added is too large, the polymer is solidified, which is not preferable. For example, when toluene, xylene, and n-butyl acetate are used as the good solvent and methanol is used as the poor solvent, the weight ratio of the good solvent and the poor solvent (good solvent: poor solvent) is 7
It is preferably in the range of 0:30 to 30:70, and more preferably 60:40 to 40:60.

When the above poor solvent is added to the solution of the cyclic olefin-based polymer in a good solvent for mixing treatment, it is preferable to add an appropriate amount of water for treatment. <Water> The amount of water added is 999/1 to 50/950, preferably 99, by weight ratio of poor solvent and water (poor solvent / water).
8 / 2-900 / 100, more preferably 997 / 3-
Used in the range of 950/50. The efficiency of removing metal compounds or other impurities from the polymer solution can be increased by adding an appropriate amount of water. If the amount of water added is too small, the efficiency of removing metal compounds and other impurities decreases. On the other hand, if the amount of water to be added is too large, it becomes difficult to separate the good solvent and the poor solvent into the good solvent phase and the poor solvent phase because the good solvent and the poor solvent are in an emulsified state,
The efficiency of removing metal compounds and other impurities is reduced.

When the mixing treatment is carried out, the treatment temperature is usually -20 to 150 ° C, preferably 0 to 130 ° C. The processing time is usually 1 minute to 10 hours,
It is preferably 10 minutes to 2 hours.

By the extraction treatment after the mixing treatment as described above, the efficiency of removing the transition metal from the good solvent phase of the metal compound residue, especially W and Mo used as one component of the polymerization catalyst, is dramatically improved. . This is because the catalytic metal compound itself is in a reduced state in the hydrogenation step by contact with the organoaluminum used as a co-catalyst during the polymerization, and the metal compound in the reduced state in the extraction step is changed by the poor solvent. It is very difficult to extract, therefore, the residual amount of impurities such as metal compounds in the polymer is large by simple extraction, the hue of the polymer solution obtained after the extraction step, the hue of the pellet after finishing, This causes deterioration of the hue of various molded products. On the other hand, the addition of the oxidizing agent causes impurities such as metal compounds to be in an oxide state and has high solubility in a poor solvent, so that the impurities are highly efficiently extracted into the poor solvent phase.

In the second purification method of the present invention, a basic compound is added to a solution of a cyclic olefin polymer in a good solvent, a poor solvent is further added, and a mixing treatment is performed by stirring or the like. Impurities are extracted by separating the phase into a good solvent phase, and the cyclic olefin polymer is recovered from the good solvent phase. As a good solvent for the polymer,
The above-mentioned thing can be used.

<Basic Compound> Specific examples of the basic compound added to the solution of the cyclic olefin polymer in a good solvent include sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide and magnesium hydroxide. Hydroxide compounds such as ammonia, inorganic compounds such as ammonia, tertiary amines such as triethylamine and tributylamine, N, N
Amide compounds such as -dimethylformamide and N, N-dimethylacetamide, 1,8-diazabicyclo [5.
Other organic base compounds such as 4.0] -7-undecene can be mentioned, and sodium hydroxide and potassium hydroxide are preferable. These compounds may be used alone or in combination of two or more. The amount of these basic compounds used is in the range of 0.0001% by weight to 10% by weight based on the cyclic olefin polymer. If the amount of the basic compound used is too small, the efficiency of removing impurities will be poor, and if it is too large, impurities will remain in the polymer and cause coloration, which is not preferable.

As the poor solvent to be added to the solution of the cyclic olefin polymer together with the basic compound in the good solvent, those described above can be used. These basic compounds may be treated by adding a basic compound to a solution of a cyclic olefin polymer in a good solvent in advance and then performing a mixed treatment by adding a poor solvent, or a basic compound and a poor solvent. Can be added at the same time and mixed. In addition, in the above-mentioned mixing treatment, it is preferable to add water in an appropriate amount as described above, and the treatment temperature is usually
-20 to 150 ° C, preferably 0 to 130 ° C. The treatment time is usually 1 minute to 10 hours, preferably 10 minutes to 2 hours.

By the above extraction treatment, the efficiency of removing the metal compound and other impurities that react with the basic compound from the good solvent phase is dramatically improved. This is because metal compounds and other impurities that are in a reduced state in the solution during the polymerization reaction or hydrogenation reaction are converted into hydroxides, for example, by the basic compound to be added, and the solubility in a poor solvent increases. , Because the hydroxide is highly efficiently extracted into the poor solvent phase. By performing this extraction treatment, the hue of the polymer solution obtained after the extraction treatment, the dissolution of the pellets, the hue of the pellets after finishing, and the hues of various molded products are significantly improved.

In the third purification method of the present invention, the extraction treatment by adding the oxidizing agent according to the above-mentioned first purification method and the extraction treatment by adding the basic compound according to the second purification method The cyclic olefin-based polymer is recovered from the good solvent phase by performing both the treatment and the treatment. As a particularly preferred specific example of the combination of the oxidizing agent and the basic compound used, the oxidizing agent is hydrogen peroxide water, and the basic compound is selected from sodium hydroxide, potassium hydroxide, ammonia and triethylamine. Can be mentioned. Here, the extraction process of impurities by adding an oxidizing agent or the like is preferably performed prior to the extraction process of impurities by adding a basic compound or the like, but the impurity extraction process by adding a basic compound or the like is preferable. It may be performed after the end of the extraction process.

As described above, the extraction process of impurities by adding an oxidizing agent or the like to the solution of the cyclic olefin polymer in a good solvent and the extraction process of impurities by adding the basic compound or the like are performed. Thus, both oxidizable impurities and other impurities, for example, impurities that react with a basic compound, can be removed from the solution with extremely high efficiency, and a highly transparent polymer can be recovered.

In the method for purifying a cyclic olefin polymer according to the present invention, it is preferable to perform a so-called pretreatment in which an acid is added to a solution of the polymer in a good solvent prior to the impurity extraction treatment. <Pretreatment> In the pretreatment, a solution of the polymer in a good solvent is mixed with an acid, a poor solvent, and an appropriate amount of water described above, and then mixed, and then separated into a poor solvent phase and a good solvent phase. Let As the acid used, those mentioned above can be used. By performing the impurity extraction treatment after the pretreatment is completed, the impurity removal efficiency can be improved as compared with the case where the extraction treatment is performed without the pretreatment.

Further, in the method for purifying a cyclic olefin polymer according to the present invention, after completion of the impurity extraction treatment,
It is preferable to perform a so-called washing treatment in which a poor solvent is added to a solution of the polymer in a good solvent to treat the polymer. <Washing treatment> In the washing treatment, the poor solvent described above is newly added to the good solvent phase containing the polymer, which has been separated by the preceding extraction treatment of impurities, and the mixing treatment is performed by stirring or the like. After that, the poor solvent phase and the good solvent phase are separated.
By carrying out this washing treatment, the oxidizing agent or basic compound and other unreacted components which are added in the extraction treatment of impurities and remain in the good solvent phase are extracted into the poor solvent phase and extracted. Can be removed from. As a result, the purified cycloolefin polymer can be recovered from the good solvent phase.

In the method for purifying a cyclic olefin polymer of the present invention, each of the above-mentioned impurity extraction treatment, pretreatment and washing treatment can be repeated a plurality of times.

The cyclic olefin polymer purified according to the present invention may be added to a known antioxidant such as 2,6-di-t-
Butyl-4-methylphenol, 2,2'-dioxy-
3,3'-di-t-butyl-5,5'-dimethyldiphenylmethane, tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane, or an ultraviolet absorber, For example, 2,4-dihydroxybenzophenone and 2-hydroxy-4-methoxybenzophenone can be added to stabilize the polymer. Further, additives such as a lubricant may be added for the purpose of improving processability.

The cyclic olefin polymer purified according to the present invention can be used to produce a molded article by known molding means such as injection molding, compression molding, extrusion molding, cast molding and the like.

On the surface of the formed article, an inorganic compound, an organic silicon compound such as a silane coupling agent, an acrylic resin, a vinyl resin, a melamine resin, an epoxy resin, a fluorine resin, a silicone resin, etc. A hard coat layer can be formed. Examples of means for forming the hard coat layer include known methods such as a heat curing method, an ultraviolet curing method, a vacuum deposition method, a sputtering method, and an ion plating method. This allows
It is possible to improve the heat resistance, optical characteristics, chemical resistance, abrasion resistance and moisture permeability of the molded product.

The use of the polymer purified by the present invention is not particularly limited and can be used in a wide range, for example, spectacle lenses, general camera lenses, pickup lenses, video camera lenses, telescopes. Lenses, lenses such as laser beam lenses, optical video discs, audio discs, document file discs, optical discs such as memory discs, optical films such as OHP films for thermal transfer and liquid jet recording, optical fibers, side emission light Particularly suitable for use as transmitters, light guide plates for liquid crystal displays, optical materials such as transparent conductive sheets, CCD lids and cases, semiconductor encapsulants, artificial marble, precision parts, and binders for ink compositions for thermal recording media. can do.

[0055]

EXAMPLES Examples of the present invention will be described below.
The present invention is not limited to these aspects. The cyclic olefin polymer solutions used in Examples and Comparative Examples were obtained according to the following synthesis examples. Also,
“Parts” used in the following description means parts by weight.

[Synthesis Example 1] 8-methyl-8-carboxymethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3 Dodecene 25
0 parts, 41 parts of 1-hexene, which is a molecular weight regulator, and 750 parts of toluene were charged into a reaction vessel purged with nitrogen,
Heated to 60 ° C. 0.62 parts of a toluene solution of triethylaluminum (concentration: 1.5 mol / l), which is a polymerization catalyst, and WC with t-butanol and methanol.
WCl ₆ modified by modifying l ₆ to give a molar ratio of t-butanol, methanol and tungsten of 0.35: 0.3: 1.
3.7 parts of solution (concentration 0.05 mol / l) was added, and the temperature was 60 ° C.
Polymer solution A was obtained by heating and stirring for 3 hours. The polymerization conversion rate in this polymerization reaction was 97%, and the intrinsic viscosity (ηinh) of the polymer was 0.45.

[0057]

[Chemical 2]

4000 parts of the obtained polymer solution A was put into an autoclave, and RuHCl (CO) [P
0.48 parts of (C ₆ H ₅ ) ₃ ] ₃ was added, and the hydrogen gas pressure was 1
The hydrogenation reaction was carried out by heating and stirring for 3 hours under the conditions of 00 kg / cm ² and reaction temperature of 165 ° C. After the obtained reaction solution is cooled, the hydrogen gas is released to give hydrogenated polymer solution B.
Got

[Synthesis Example 2] 8-ethylidenetetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3
A ring-opening polymerization reaction was carried out in the same manner as in Synthesis Example 1 except that 200 parts of dodecene was used to obtain a polymer solution C, which was then hydrogenated to obtain a hydrogenated polymer solution D.

[Synthesis Example 3] A reaction vessel equipped with a stirring blade, a gas introduction tube, a thermometer and a dropping funnel was sufficiently replaced with nitrogen gas, and 2000 parts of cyclohexane dehydrated and dried with a molecular sieve was placed in the reaction vessel. In a nitrogen atmosphere, 75 parts of tetracyclododecene and 6.6 parts of a solution of ethylaluminum sesquichloride in n-hexane (concentration 1 mol / l) were added. Next, while maintaining the internal temperature of the reaction vessel at 10 ° C., in the reactor, from the gas introduction pipe,
A mixed gas of ethylene and nitrogen (flow rate of ethylene: 10 liter / Hr, flow rate of nitrogen: 40 liter / Hr) was set to 10
I passed for a minute. To this solution, n of VO (OC ₂ H ₅ ) Cl ₂ was added.
-Twenty-three parts of a hexane solution (concentration 0.07 mol / l) was added dropwise from the dropping funnel to start the copolymerization reaction, and the reaction was carried out while passing the mixed gas. After 30 minutes had elapsed from the start of the reaction, 45 parts of methanol was added to the reaction solution to stop the polymerization reaction, and a polymer solution E was obtained.

The hydrogenated polymer solutions or polymer solutions obtained in the above Synthesis Examples 1 to 3 were subjected to extraction purification treatment according to the following Examples and Comparative Examples.

Example 1 As the first step, 25,000 of hydrogenated polymer solution B was prepared.
Parts were placed in a reaction vessel, 35 parts of lactic acid, 50 parts of water and 500 parts of methanol were added, and the mixture was stirred at 60 ° C. for 30 minutes. Next, add 12,500 more parts of methanol and add 1 at 60 ° C.
Further stirred for hours. Then, the mixture was cooled to room temperature and separated into a poor solvent phase (methanol phase) and a good solvent phase (polymer-containing phase), and the poor solvent phase was removed. In the second step, a solvent having the same composition and the same amount as the poor solvent phase removed earlier is added to the good solvent phase, and further 35 parts of lactic acid and hydrogen peroxide solution (concentration 30
%) 2.4 parts and 50 parts of water were added. 1 at 60 ℃
After stirring for a period of time, the mixture was cooled to room temperature and separated into a poor solvent phase and a good solvent phase, and the poor solvent phase was removed. In the third step, a solvent having the same composition and the same amount as the poor solvent phase removed previously was added to the good solvent phase, and the mixture was stirred at 60 ° C. for 1 hour, and then cooled to room temperature to cool the poor solvent phase and the good solvent. The phases were separated and the poor solvent phase was removed. As the fourth step, a solvent having the same composition and the same amount as the poor solvent phase removed earlier was added to the good solvent phase, and further 124 parts of a methanol solution of potassium hydroxide (concentration 5%) and 50 parts of water were added. It was This was stirred at 60 ° C. for 1 hour, cooled to room temperature, separated into a poor solvent phase and a good solvent phase, and the poor solvent phase was removed. As a fifth step, a solvent having the same composition and the same amount as the poor solvent phase removed earlier is added to the good solvent phase,
This was stirred at 60 ° C. for 1 hour, cooled to room temperature, separated into a poor solvent phase and a good solvent phase, and the cyclic olefin polymer was recovered from the good solvent phase. Note that all of these extraction operations were performed under a nitrogen atmosphere.

Example 2 As the first step, 25,000 of hydrogenated polymer solution B was prepared.
35 parts of lactic acid, 2.4 parts of hydrogen peroxide solution (concentration 30%), 50 parts of water, and 500 parts of methanol were added, and the mixture was stirred at 60 ° C. for 30 minutes. Next, 12500 parts of methanol was added, and the mixture was further stirred at 60 ° C. for 1 hour. Then, it cooled to room temperature, the poor solvent phase and the good solvent phase were isolate | separated, and the poor solvent phase was removed. As the second step,
A solvent having the same composition and the same amount as the poor solvent phase removed earlier was added to the good solvent phase, and 35 parts of lactic acid and 50 parts of water were further added thereto. This was stirred at 60 ° C. for 1 hour, cooled to room temperature, separated into a poor solvent phase and a good solvent phase, and the poor solvent phase was removed. In the third step, a solvent having the same composition and the same amount as the poor solvent phase removed previously was added to the good solvent phase, and the mixture was stirred at 60 ° C. for 1 hour, and then cooled to room temperature to cool the poor solvent phase and the good solvent. The phases were separated and the poor solvent phase was removed. As the fourth step,
A solvent having the same composition and the same amount as the poor solvent phase removed earlier was added to the good solvent phase, and further 2 parts of ammonia water (concentration 25%) and 50 parts of water were added thereto. This was stirred at 60 ° C. for 1 hour, cooled to room temperature, separated into a poor solvent phase and a good solvent phase, and the poor solvent phase was removed. In the fifth step, a solvent having the same composition and the same amount as the previously removed poor solvent phase was added to the good solvent phase, and the mixture was stirred at 60 ° C. for 1 hour and then cooled to room temperature to cool the poor solvent phase and the good solvent. The polymer was recovered from the good solvent phase. Note that all of these extraction operations were performed under a nitrogen atmosphere.

Example 3 The same procedure as in Example 1 was repeated except that lactic acid was not added in the second step and 11 parts of triethylamine was added in place of the methanol solution of potassium hydroxide in the fourth step. Then, the cyclic olefin polymer was recovered.

Example 4 In the second step, 0.35 part of ferric chloride was added in place of the hydrogen peroxide solution, and in the fourth step, sodium hydroxide in methanol was used instead of potassium hydroxide in methanol. (Concentration 5%) except that 90 parts was added
The same operation as in Example 1 was performed to recover the cyclic olefin polymer.

Example 5 In the fourth step, the same operation as in Example 1 was carried out except that 4 parts of ammonia water having a concentration of 25% was added instead of the methanol solution of potassium hydroxide, and the cyclic olefin-based polymer was added. The coalescence was collected.

Example 6 In the second step, hydrogen peroxide solution (concentration: 30
%) 2.4 parts was added, and in the fourth step, the same operation as in Example 2 was carried out except that 11 parts of triethylamine was added instead of aqueous ammonia, and the cyclic olefin polymer was recovered. .

Example 7 The cyclic olefin polymer was recovered in the same manner as in Example 1 except that the methanol solution of potassium hydroxide and water were not added in the fourth step.

Example 8 In the second step, the same operation as in Example 1 was carried out except that the hydrogen peroxide solution was not added, and the cyclic olefin polymer was recovered.

Comparative Example 1 The same operation as in Example 1 was performed except that hydrogen peroxide solution was not added in the second step, and methanol solution of potassium hydroxide and water were not added in the fourth step. Then, the cyclic olefin polymer was recovered.

Comparative Example 2 Except that hydrogen peroxide solution was not added in the first step, lactic acid and water were not added in the second step, and ammonia water and water were not added in the fourth step. Then, the same operation as in Example 2 was performed to recover the cyclic olefin polymer.

Example 9 As the first step, 25,000 of hydrogenated polymer solution B was prepared.
Parts were placed in a reaction vessel, 35 parts of lactic acid, 50 parts of water and 500 parts of methanol were added, and the mixture was stirred at 60 ° C. for 30 minutes. Next, add 12,500 more parts of methanol and add 1 at 60 ° C.
Further stirred for hours. Then, it cooled to room temperature, the poor solvent phase and the good solvent phase were isolate | separated, and the poor solvent phase was removed. In the second step, a solvent having the same composition and the same amount as the poor solvent phase removed earlier was added to the good solvent phase, and 35 parts of lactic acid, 2.4 parts of hydrogen peroxide solution (concentration 30%) and 50 parts of water were further added thereto. And added.
This was stirred at 60 ° C. for 1 hour, cooled to room temperature, separated into a poor solvent phase and a good solvent phase, and the poor solvent phase was removed. In the third step, a solvent having the same composition and the same amount as the poor solvent phase removed earlier was added to the good solvent phase, and 35 parts of lactic acid, 2.4 parts of hydrogen peroxide solution (concentration 30%) and 50 parts of water were further added thereto. And added. This was stirred at 60 ° C. for 1 hour, cooled to room temperature, separated into a poor solvent phase and a good solvent phase, and the poor solvent phase was removed. In the fourth step, a solvent having the same composition and the same amount as the poor solvent phase removed previously was added to the good solvent phase, and this was added at 60 ° C. for 1 hour.
After stirring for a period of time, the mixture was cooled to room temperature and separated into a poor solvent phase and a good solvent phase, and the poor solvent phase was removed. In the fifth step, a solvent having the same composition and the same amount as the poor solvent phase removed earlier was added to the good solvent phase, and further 124 parts of a methanol solution of potassium hydroxide (concentration 5%) and 50 parts of water were added. It was This was stirred at 60 ° C. for 1 hour, cooled to room temperature, separated into a poor solvent phase and a good solvent phase, and the poor solvent phase was removed. In the sixth step, a solvent having the same composition and the same amount as the poor solvent phase removed earlier was added to the good solvent phase, and the mixture was stirred at 60 ° C. for 1 hour, and then cooled to room temperature to cool the poor solvent phase and the good solvent. And the cyclic olefin polymer was recovered from the good solvent phase. Note that all of these extraction operations were performed under a nitrogen atmosphere.

Example 10 The same procedure as in Example 9 was conducted except that 2 parts of 25% ammonia water was added in place of the methanol solution of potassium hydroxide in the fifth step, and the cyclic olefin-based polymer was added. The coalescence was collected.

Example 11 In the second step, the amount of hydrogen peroxide solution added was changed to 12 parts, in the third step the amount of hydrogen peroxide solution added was changed to 5 parts, and in the fifth step potassium hydroxide was added. The cyclic olefin polymer was recovered in the same manner as in Example 9, except that 11 parts of triethylamine was added instead of the methanol solution in Example 1.

Comparative Example 3 Similar to Example 9 except that hydrogen peroxide solution was not added in the second and third steps, and methanol solution of potassium hydroxide and water were not added in the fifth step. And then
The cyclic olefin polymer was recovered.

Example 12 Instead of hydrogenated polymer solution B, hydrogenated polymer solution D
In the same manner as in Example 1 except that was used, a cyclic olefin polymer was recovered.

Example 13 The cyclic olefin polymer was recovered in the same manner as in Example 1 except that the polymer solution E was used instead of the hydrogenated polymer solution B.

The above Examples 1 to 13 and Comparative Examples 1 to
For each of the cyclic olefin-based polymers purified and recovered according to No. 3, a molded article for measurement was prepared in order to quantify the metal element contained as an impurity and to measure the hue of the polymer. [Preparation of molded article for measurement] To 100 parts of the purified and recovered cyclic olefin polymer, 0.2 part of Irganox 1076 (manufactured by Ciba-Geigy) was added as an antioxidant,
Pellets were produced by an extruder (extrusion temperature: 290 ° C). Injection molding machine "IS90" using the produced pellets
B ”(manufactured by Toshiba Machine Co., Ltd.) was used to perform injection molding at a molding temperature of 210 ° C. to produce a flat plate having a thickness of 3 mm, which was used as a molded product for measurement.

[Quantification of Metal Element] Using the above-mentioned molded article for measurement, the metal element contained in the cyclic olefin polymer was quantified by the following method. Aluminum: Atomic absorption method Ruthenium: Atomic absorption method Tungsten: Colorimetric method Vanadium: Atomic absorption method The results are shown in Tables 1 to 4.

[Evaluation of Hue] Regarding the hue of the above-mentioned molded article for measurement, the degree of yellowness was measured according to JIS K7105 (transmission method). The results are shown in Tables 1 to 4. Tables 1-4 shown below
In the above, "lactic acid" is lactic acid 35 unless otherwise specified.
Part, "hydrogen peroxide water" is hydrogen peroxide water (concentration 30%)
2.4 parts, "ferric chloride" is 0.35 parts ferric chloride,
"Potassium hydroxide" is 124 parts of potassium hydroxide in methanol (concentration 5%), "Sodium hydroxide" is 90 parts of sodium hydroxide in methanol (concentration 5%), and "Ammonia water" is ammonia water (concentration 25%). %) 2 parts, “triethylamine” means that 11 parts of triethylamine were added, respectively.

[0081]

[Table 1]

[0082]

[Table 2]

[0083]

[Table 3]

[0084]

[Table 4]

[0085]

EFFECTS OF THE INVENTION According to the method for purifying a cyclic olefin polymer of the present invention, impurities can be extracted and removed from a solution containing the produced cyclic olefin polymer with high efficiency. The cyclic olefin-based polymer removed in step 1 can be recovered. The purified polymer has almost no coloring observed immediately after its production by the polymerization reaction, and an excellent molded article having high transparency can be obtained. Therefore, it can be suitably used as a wide variety of optical materials.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Akira Iio 2-11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd.

Claims (1)

[Claims] 1. A method for purifying a cyclic olefin-based polymer produced by ring-opening polymerization using a catalyst containing a metal element, which comprises adding an oxidizing agent to a solution of the cyclic olefin-based polymer and adding a poor solvent to the solution. A method for purifying a cyclic olefin polymer, comprising a step of extracting and removing impurities and / or a step of adding a basic compound and extracting and removing impurities with a poor solvent.