JPH0560483B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for purifying a copolymer of ethylene and an α-olefin having 3 or more carbon atoms, which is produced using a catalyst formed from a vanadium compound and an organoaluminum compound. . More specifically, the catalyst component is extracted from a polymer solution obtained using a polymer-soluble inert organic solvent in the presence of a catalyst, or from a high molecular weight polymer obtained in the presence of a medium that does not dissolve the polymer. The present invention relates to a method for purifying a polymer to be removed. [Prior art] As a method for removing the catalyst component from a copolymer of ethylene and α-olefin produced using a vanadium catalyst, water is added to a polymer solution, mixed with a mixer, etc., and the catalyst component is removed. A method in which the aqueous phase and the organic solvent phase are separated, and a polymer with reduced catalyst components is obtained from the organic solvent phase, or a slurry obtained by copolymerization in a medium that does not dissolve the polymer, and water is added to the slurry obtained by copolymerization in a medium that does not dissolve the polymer Alternatively, a method of reducing catalyst residue by adding alcohol is known as a conventional technique. (For example, Koji Saeki, "Polymer Manufacturing Process," Kogyo Kenkyukai, 1971) However, these methods have several drawbacks. For example, in the method of extraction with water, as the polymer is dissolved in an inert organic solvent and the viscosity of the solution becomes high, removal of the catalyst becomes difficult. This is thought to be due to the catalyst component being solubilized in water being extracted by the contact between the catalyst and water.
This is thought to be because when the viscosity of the solution becomes high, for example 1000 to 5000 cp, the polymer solution and water are not mixed to a satisfactory degree, and as a result, the catalyst component is not sufficiently extracted into water and a large amount of catalyst components will remain in the polymer. In order to improve the mixing condition, it is possible to improve the performance of the mixing mixer, for example by increasing the rotation speed, but this requires a large amount of power.
It is not industrially advantageous. In addition, in the method using alcohol, the used alcohol is generally purified and reused, which is a complicated method and consumes a large amount of energy, which is not advantageous. Containing a large amount of catalyst residue in the polymer
This causes discoloration of the polymer, deterioration of weather resistance, deterioration of heat resistance, etc., and various performances as a polymer are significantly deteriorated. In order to overcome this problem, proposals have been made for mixers with good mixing characteristics. Furthermore, many proposals have been made for methods of producing polypropylene using epoxy compounds, organic acids, etc. as extractants. (JP-A No. 57-403, JP-A No. 55-112208) [Problems to be solved by the invention] However, it is possible to obtain rubber-like copolymers without substantially requiring post-treatment or purification steps. In order to efficiently remove catalyst residues from highly viscous solutions or slurries, these known techniques still have some problems to be overcome. The purpose of the present invention is to solve such problems, and in particular to produce a solution containing a rubbery copolymer produced using a vanadium-based catalyst, without substantially requiring post-treatment or purification, and therefore requiring less equipment. Another object of the present invention is to provide a method for extracting catalyst components that does not require extra costs, and an effective extractant. [Means for solving the problem] In view of the above situation, the present inventors have conducted extensive research and
As a result of repeated studies, we found that at 25℃ as an extractant,
The inventors discovered that by using an aliphatic polycarboxylic acid or an aliphatic oxypolycarboxylic acid having a constant first-stage dissociation constant for water, catalyst residues can be extracted and removed extremely efficiently, and the present invention has been achieved. . That is, the present invention provides a copolymer of ethylene and an α-olefin having 3 or more carbon atoms produced using a catalyst formed from a vanadium compound and an organoaluminum compound, or a linear copolymer having a nonconjugated double bond with these copolymers. Alternatively, in a method for removing a catalyst component from a copolymer consisting of a cyclic diene, only an aqueous solution of an aliphatic polycarboxylic acid or aliphatic oxypolycarboxylic acid having a first-stage dissociation constant of 1.0 to 4.0 at 25°C is added. The present invention relates to a method for purifying a polymer, which is characterized in that the copolymer is in a solution state in which the copolymer is dissolved in an inert solvent. More specifically, ethylene and α- having 3 or more carbon atoms
Olefins or linear or cyclic dienes having non-conjugated double bonds are mixed with olefins in an inert organic solvent such as pentane, hexane, etc. in the presence of a catalyst formed from a vanadium compound and an organoaluminum compound. The present invention relates to a method for removing a catalyst component from a rubbery copolymer solution obtained using a coalescence-soluble solvent. Among the most typical catalysts used in the production of these rubbery copolymers, vanadium compounds include, for example, VC _l4 , VOC _l3 , VO(OR) _3-o C _lo (R is a straight line with 1 to 10 carbon atoms). Examples of organoaluminum compounds used as cocatalysts include A _l RnC _l3-o (R is a linear or A branched alkyl group (3≧n≧0) is exemplified. As a method for polymerizing the rubbery polymer, a method is used in which an inert hydrocarbon capable of dissolving the polymer is used as a solvent. The rubbery copolymer is, for example, ethylene or propylene rubber, and the Mooney viscosity measured at 121°C is 10-10.
150, and those having an ethylene content of 45 to 90% by weight, but are not limited to these. When removing catalyst from rubbery copolymer solutions,
Conventionally, extraction was performed by adding water, but the viscosity of the solution was high, e.g. 1000 to 5000 cp.
It was difficult to remove the catalyst. In the present invention, a catalyst component is extracted from a polymer solution using an aqueous solution containing an aliphatic polycarboxylic acid or an aliphatic oxypolycarboxylic acid having a first-stage dissociation constant of 1.0 to 4.0 at 25°C. It has been discovered that catalyst components can be removed with surprising efficiency. The polycarboxylic acid or oxypolycarboxylic acid used in the present invention has a first-stage dissociation constant of 1.0 to 4.0 at 25°C, and examples thereof include oxalic acid, malic acid, malonic acid, tartaric acid, maleic acid, and citric acid. be done. The first stage dissociation constant in the present invention is measured by electrical conductivity measurement. This method is described, for example, in "Physical Chemistry Experimental Methods" (Kohei Goto, Kyoritsu Shuppan, 1958), pages 105 onwards. Specifically, the specific conductivity κ of solutions diluted to various concentrations is measured using a conductivity meter using Wheatstone and Bridge, and the equivalent conductivity Λ is calculated using the following formula. Λ=1000/Nκ (Λ: equivalent conductivity, N: normality) Furthermore, calculate the sum of the equivalent conductivities of each ion to obtain Λ _∞ (equivalent conductivity at infinite dilution), and calculate the ionization constant using the following formula. Find K K=Λ ² /Λ _∞ (Λ _∞ −Λ) ν (ν: degree of dilution) From the ionization constant K, the first stage dissociation constant (pK ₁ ) is determined from the following equation. pK ₁ =−logK When these aliphatic polycarboxylic acids or aliphatic oxypolycarboxylic acids are brought into contact with a catalyst residue-containing polymer, it is necessary to bring them into contact as an aqueous solution. These aliphatic polycarboxylic acids and aliphatic oxypolycarboxylic acids are used in an amount of 0.5 to 200 molar equivalents per mole of vanadium as a catalyst component (this concentration is 0.5 to 200 molar equivalents).
It is desirable to use 1 to 100 times the molar amount), preferably 1 to 100 times the molar amount. If the amount is below the above range, the effect of the present invention cannot be obtained, and although it may be used above the above range, it will only increase the cost and no increase in the effect can be expected. In carrying out the present invention, the aliphatic polycarboxylic acid or aliphatic oxypolycarboxylic acid is used as an aqueous solution, and the volume concentration of the aqueous solution is usually 0.1 to 1.0 parts, preferably 0.2 parts, per 1 part of the polymer solution. ~0.5 parts. The present invention is to extract and remove catalyst components from a high viscosity solution in which a polymer is dissolved. In that case, the stirring time of the polymer solution and aqueous solution is
Usually 0.2 to 60 minutes are used, preferably 0.5 to 20 minutes.
It's a minute. However, it can be changed depending on the viscosity of the solution, the rotation speed of the mixer, etc., and there are no particular limitations. Thereafter, the polymer solution and the aqueous phase are separated by standing and the aqueous phase is discharged from the lower part. When the solvent is separated from the polymer solution thus treated by well-known methods such as steam stripping, a polymer containing very little catalyst residue is recovered. [Example] The present invention will be explained below with reference to Examples, but the present invention is not limited thereto. Polymerization method of copolymer Using a pressure autoclave of 27, ethylene was added in the presence of ethylaluminum sesquichloride (0.014Kg/Hr) and vanadium oxytrichloride (0.0018Kg/Hr) in a hexane (65/Hr) solution. (1.4Kg/Hr), propylene (4.7Kg/Hr), dicyclopentadiene (0.16Kg/Hr) and hydrogen (0.00047Nm ³ /Hr) as a molecular weight regulator,
The reaction was carried out at a reaction temperature of 50°C. The pressure at this time is maintained at 7.5Kg/cm ³ . The solution viscosity of the polymer solution thus obtained was 100 cp (centipoise). Further, the desired viscosity of the polymer solution was obtained by changing the amount of hexane as a solvent. (2000cp
For 5000 cp, hexane 57/Hr; for 5000 cp, hexane 48/Hr) Solution viscosity Measured at 25°C using a B type viscosity type manufactured by Tokyo Keiki. Analytical and Measuring Method for Catalyst Components A Rigaku Denki Model 3064M-2 fluorescent X-ray analyzer equipped with a Marklet rhodium tube was used. Example 1 Oxalic acid (25°C,
Add 30 parts of a 0.2% aqueous solution with a first-stage dissociation constant of 1.40 (10 times the mole relative to the added vanadium),
Stir for 15 minutes. Thereafter, this mixture was allowed to stand for about 20 minutes, and then centrifuged to completely separate the polymer solution and the aqueous phase, and then the solvent was removed from the polymer solution by conventional steam stripping. Analysis of the catalyst residue components of the obtained polymer revealed that Al ₂ O ₃ was 43 ppm and V ₂ O ₅ was 3 ppm. Comparative Example 1 A polymer was obtained in the same manner as in Example 1, except that 30 parts of water was added to 100 parts of a hexane solution of the same polymer as in Example 1. Analysis of the catalyst residue revealed 190 ppm of Al ₂ O ₃ .
The concentration of V ₂ O ₅ was 46 ppm. Comparative Example 2 To a hexane solution of the same polymer as in Example 1, 30 parts of a 0.67% by weight aqueous solution of hairdipic acid (25°C, first stage dissociation constant 4.40) was added (based on the added vanadium).
(10 times the mole) and the same operation as in Example 1 was performed to obtain a polymer. Analysis of the catalyst residue revealed 670 ppm of Al ₂ O ₃ .
The concentration of V ₂ O ₅ was 160 ppm. Example 2 To 100 parts of a hexane solution (viscosity: 2000 cp) of the polymer obtained by the above method, 60 parts of a 0.2% by weight aqueous solution of oxalic acid was added (10 parts based on the added vanadium).
double molar) and stir for 15 minutes. Thereafter, a polymer was obtained in the same manner as in Example 1. Analysis of the catalyst residue revealed 50 ppm of Al ₂ O ₃ .
The concentration of V ₂ O ₅ was 6 ppm. Examples 3 to 5 60 parts of an aqueous solution containing a desired amount of extractant was added to 100 parts of a hexane solution of the same polymer as in Example 2, and a polymer was obtained in the same manner as in Example 1. The results of the analysis of the catalyst residue are shown in Table 1. Example 6 To 100 parts of a hexane solution (viscosity 5000 cp) of the polymer obtained by the above method, 60 parts of a 2% by weight aqueous solution of oxalic acid was added (based on the added vanadium).
(100 times mole) Stir for 15 minutes. Thereafter, a polymer was obtained in the same manner as in Example 1. Analysis of the catalyst residue showed 60 ppmV ₂ O ₅ in Al ₂ O ₃
It was 6ppm. Comparative Examples 3 and 4 To 100 parts of a hexane solution of the same polymer as in Example 2,
In Comparative Example 3, only water was added, and in Comparative Example 4, 60 parts of a 1.2% by weight aqueous solution of succinic acid (first stage dissociation constant 4.17) was added (44 times the mole relative to the added vanadium), and heavy Obtained union. The analysis results of the catalyst residue are shown in Table 2. From the results of these Examples and Comparative Examples, in the case of only water or a polybasic acid with a first-stage dissociation constant exceeding 4, the effect of extracting the catalyst residue is small, and the Examples according to the present invention are superior. I know that there is.

【table】

〔Effect of the invention〕

As mentioned above, when the viscosity of the solution in which the rubbery copolymer is dissolved is as high as 1000 to 5000 cp, or when the rubbery copolymer obtained in the form of a slurry, it is difficult to remove the catalyst component using conventional methods. However, by using the present invention, it is possible to remove the catalyst component more efficiently than before, and with almost no increase in equipment costs, an improved rubbery copolymer can be produced. It is preferably used as a method for obtaining coalescence.

Claims (1)

[Scope of Claims] 1. A copolymer of ethylene and an α-olefin having 3 or more carbon atoms produced using a catalyst formed from a vanadium compound and an organoaluminum compound, or a linear copolymer with these and a non-conjugated double bond. In a method for removing a catalyst component from a copolymer consisting of a chain or cyclic diene, the first stage dissociation constant is 1.0 to 1.0 at 25°C.
A method for purifying a polymer, characterized in that only an aqueous solution of an aliphatic polycarboxylic acid or aliphatic oxypolycarboxylic acid having a molecular weight of 4.0 is added, and the copolymer is in a solution state dissolved in an inert solvent. 2. The polymer according to claim 1, wherein the aliphatic polycarboxylic acid or aliphatic oxypolycarboxylic acid is at least one acid selected from oxalic acid, malic acid, malonic acid, tartaric acid, maleic acid, and citric acid. How to refine coalescence. 3 Aliphatic polycarboxylic acid or aliphatic oxypolycarboxylic acid is 1 to 1 mole of vanadium
A method for purifying the polymer according to claim 1, which is 100 times the molar amount.