JPH0665320A - Method for purifying elastomeric olefinic copolymer - Google Patents

Abstract

PURPOSE:To eliminate a catalyst component from an elastomeric olefinic copolymer obtd. by the suspension polymn. of ethylene and propylene or ethylene, propylene, and a nonconjugated diene in a hydrocarbon. CONSTITUTION:An org. solvent having a solubility parameter of 7.3-9.5 is added to the polymn. system before and during and/or after the polymn., and 0. 2-100 pts.wt. alcohol (based on 1 pt.wt. the resulting olefin copolymer) is added to the system after the polymn.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The method for purifying an elastomeric olefinic copolymer of the present invention is a method for purifying an elastomeric olefinic copolymer such as an ethylene / propylene rubber or an ethylene / propylene / diene terpolymer (hereinafter referred to as “olefin”). Abbreviated as "type copolymer"). More specifically, in a hydrocarbon such as liquid propylene that does not substantially dissolve the produced olefin-based copolymer, ethylene, propylene, and if necessary, a non-conjugated diene-based hydrocarbon from a vanadium compound and an organoaluminum compound The present invention relates to a method for removing a catalyst residue from an olefin copolymer obtained by suspension polymerization using a Ziegler-Natta catalyst.

[0002]

BACKGROUND OF THE INVENTION Olefin-based copolymers are generally 3
It has been produced by a method of copolymerizing ethylene and propylene or ethylene, propylene and a non-conjugated diene hydrocarbon with a transition metal compound such as a valent or pentavalent vanadium compound and an organoaluminum compound as a catalyst. Then, as an industrial process, a suspension polymerization method in which polymerization is performed in liquid propylene and a solution polymerization method in which polymerization is performed in an organic solvent such as n-hexane have been mainly performed.

The solution polymerization method has an advantage in that the olefin-based copolymer formed during the polymerization hardly precipitates, so that the clogging in the reactor hardly occurs. Also, since the polymerization pressure is low, the reactor can be designed, manufactured, and operated easily, and the solution can be easily transferred after the polymerization. Further, since the deashing operation is extremely easy, it is possible to easily obtain an olefin-based copolymer having an extremely low content of catalyst residue (about 5 ppm). Therefore, conventionally,
The solution polymerization method was mainly used.

However, in the solution polymerization method, the viscosity of the polymerization solution rapidly increases as the polymerization proceeds, so the concentration of the olefin polymer is limited to about 7 to 10%,
The molecular weight could not be increased. It was also difficult to remove the heat of polymerization. Further, there is also a problem that the process is complicated because a deashing process, a solidification process, a solvent recovery process, etc. are required. Therefore, in recent years, it has been studied to adopt a suspension polymerization method which does not have such a defect.

[0005]

In the suspension polymerization method, since the polymerization proceeds in the state of a slurry liquid in which an olefinic copolymer is suspended in a liquid propylene in a particulate form, the polymerization system does not have a high viscosity. . Therefore, the concentration and molecular weight of the olefin-based copolymer may be increased as compared with the solution method. Moreover, the heat of polymerization is extremely easily removed by the latent heat of vaporization of propylene. Furthermore, it is easy to control the monomer composition ratio in the olefin-based copolymer.

However, in this polymerization method, since the copolymer is formed so as to enclose the catalyst, it is difficult to remove the catalyst by deashing after the polymerization.

When the vanadium concentration in the olefin-based copolymer is high, the olefin-based copolymer tends to be colored yellow or brown or easily deteriorate. In addition, the electrical characteristics also deteriorate. Therefore, there is a strong demand for an olefin-based copolymer having a low vanadium concentration.

In order to solve the disadvantage of the conventional suspension polymerization method that the concentration of vanadium in the obtained olefinic copolymer is high, an activator such as ethyl monochloromalonate or ethyl dichloromalonate is added to the polymerization system. It was studied to reduce the vanadium concentration of the olefin-based copolymer itself produced in the polymerization step by adding it to improve the activity of the catalyst. However, by this method alone, an olefin-based copolymer having a sufficiently low vanadium concentration could not be obtained. Therefore, improvement of the deashing process was also examined. First, a deashing method in which the slurry obtained in the polymerization step was washed with water, an alkaline aqueous solution, a tartaric acid aqueous solution, or the like was examined (Japanese Patent Publication No. 46-51516). In addition to this, a method was considered in which hydrochloric acid, acetic acid, an extract such as an aqueous solution of caustic soda, a complexing solution such as tartaric acid or gluconic acid, and an oxidizing agent were added to the slurry, and then an organic solvent such as toluene was mixed. (Japanese Patent Publication No. 46-5156). Furthermore, a method of adding polyether diamine or polyether monoamine to the slurry after polymerization and then washing with water (Japanese Patent Publication No. 46-6).
985) or a method of adding a good solvent and a surfactant and then adding water (JP-A-60-69112).

However, since all of these methods extract the catalyst residue in the water layer, a large amount of treated wastewater is generated, and this treatment is troublesome.

Therefore, a method of removing the catalyst residue in a non-aqueous system has been studied. As such a method, first, a method of washing the produced olefin-based copolymer with liquid propylene was studied (JP-A-62-96504). In this method, since the catalyst is not deactivated by washing, the catalyst removed from the olefin-based copolymer can be reintroduced into the polymerization step. Further, since no catalyst deactivator is used, contamination of the polymerization reactor is extremely small.
Furthermore, since almost no aqueous solution is used, there is an advantage that almost no waste water is generated. However, even with this method, it was difficult to remove vanadium from the olefin copolymer to a satisfactory level, for example, a concentration of about 10 ppm. It is an object of the present invention to provide a method for removing a catalyst residue in a non-aqueous system, which is a method for purifying an olefinic copolymer which can remove vanadium to about 10 ppm.

[0011]

[Technical Means for Solving the Problems] The purification method of the present invention comprises:
To a suspension of an olefinic copolymer obtained by suspension polymerization of ethylene, propylene or the like, an organic solvent having a solubility parameter in a specific range and a specific amount of alcohol are added, and a catalyst residue is added to the alcohol. Is to extract. The purification method of the present invention can be applied to suspension polymerization in liquid propylene. In addition, it can be applied to suspension polymerization in a solvent other than liquid propylene, which does not substantially dissolve the olefin-based copolymer and does not react with the catalyst. In suspension polymerization, the olefin-based copolymer is usually dispersed in the form of particles, but in the present invention, the particles of the olefin-based copolymer are swollen with an organic solvent, and the alcohol easily penetrates inside the particles. By doing so, the catalyst residue inside the particles is also effectively removed. Hereinafter, the present invention will be described in more detail.

The organic solvent may be added after the polymerization,
It may be added during or before the polymerization. When it is added before the polymerization, it may be added as a diluent for the catalyst. For example, when vanadium triacetylacetonate is used as the main catalyst vanadium compound, since vanadium triacetylacetonate is a solid, it can be added by dissolving it in the above organic solvent. Further, a part may be added before the polymerization and the rest may be added during the polymerization or after the polymerization. When the organic solvent is added after the polymerization, it may be added separately or in combination with the alcohol. When the alcohol is added separately, it may be added before or after the alcohol is added. However, the amount of the organic solvent added is preferably in the range of 0.02 to 0.4 part by weight with respect to 1 part by weight of propylene charged during the polymerization. In particular, the range of 0.04 to 0.2 is preferable. When the amount of the organic solvent added is less than 0.02 part by weight, the swelling effect of the copolymer is small, and when it is more than 0.4 part by weight, the viscosity of the polymerization system increases, which is not preferable.

The organic solvent used in the present invention has a solubility parameter of 7.3 to 9.5. A solvent having a solubility parameter smaller than 7.3 has a small polymer swelling effect, and a solvent having a solubility parameter larger than 9.5 has a small catalyst removal effect. If the solubility parameter is within this range, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons,
Any type of solvent such as ether, ketone, ester, etc. can be used. Examples of such a solvent include n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-undecane, n-dodecane, cycloheptane, cyclohexane, methylcyclohexane, benzene, toluene, xylene, Ethylbenzene, styrene,
Methyl ethyl ketone, diethyl ether, dipropyl ether, ethyl acetate, acetic acid, chloroform, tetrachloroethane and the like can be mentioned. These solvents may be used alone or in combination of two or more.

In the present invention, alcohol is added after polymerization. The amount of alcohol added to the polymerization system is such that the weight ratio to the produced olefinic copolymer is 0.2 to 10.
It is necessary to set it in the range of 0, and it is particularly preferable to set it in the range of 0.5 to 10. When the ratio of alcohol to the olefin-based copolymer is less than 0.2, the extraction efficiency of the catalyst residue is too low to achieve the object of the present invention. On the other hand, even if the proportion of alcohol is more than 100, the extraction efficiency of the catalyst residue is no longer improved, and the added alcohol is simply wasted.

In the present invention, the preferable alcohol is represented by ROH. Here, R is an alkyl group having 1 to 12 carbon atoms or an arylalkyl group. Specifically, methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-
Butyl alcohol, isobutyl alcohol, n-amyl alcohol, isoamyl alcohol, hexyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol and other aliphatic saturated alcohols, cyclopentanol, cyclohexanol and other alicyclic alcohols, allyl alcohol, crotyl Aliphatic unsaturated alcohols such as alcohol and aromatic alcohols such as benzyl alcohol and cinnamyl alcohol are used. The most preferred of these is an aliphatic saturated alcohol.

The operating temperature is 0 to 60 ° C., especially 10 to 30 ° C.
Is preferred. The operating time is not particularly limited, but from 5 minutes
A range of 3 hours is preferred.

[0017]

Since the organic solvent and alcohol are used in the purification method of the present invention, almost no treated waste water is generated. Further, an olefin-based copolymer having a vanadium content of about 10 ppm can be easily obtained. Although waste liquid is generated also in the purification method of the present invention, almost all the organic solvent and alcohol can be easily recovered by distillation or the like, so that the discharge amount of waste liquid can be extremely small.

[0018]

EXAMPLES The present invention will be specifically described below with reference to examples.

Example 1 In a stainless steel autoclave having an internal volume of 2 liters, 500 g of liquid propylene and 5-
14.4 ml of ethylidene-2-norbornene, 5.76 mmol of diethyl aluminum chloride and 0.1 mmol of diethyl zinc were charged. Then, the polymerization temperature is set to 20 ° C., ethylene is added while stirring the content.
While supplying at a pressure higher by 3 kg / cm ² and G than the internal pressure of the autoclave, a solution of 0.129 mmol of vanadium triacetylacetonate in 8 ml of toluene was supplied to initiate polymerization. The polymerization was carried out for 45 minutes.
As an activator, a mixture of ethyl monochloromalonate and ethyl dichloromalonate in a molar ratio of 3: 7 was used, and 0.26 mmol of this mixture was added to 6 ml of toluene.
It was supplied to the autoclave as a solution dissolved in. The toluene solution of vanadium triacetylacetonate and the activator was continuously supplied from the beginning to the end of the polymerization. The supply start time of these toluene solutions was used as the polymerization start time, and the supply end time was used as the polymerization end time. After 45 minutes, 20 ml of toluene was pressed into the autoclave, and ethyl alcohol was immediately added at a rate of 2.5 ml per minute for 2 minutes.
Pump for 0 minutes. Further, add 4 parts of ethyl alcohol.
50 ml was poured and the contents of the autoclave were vigorously stirred at 20 ° C. for 30 minutes. After stirring the content, unreacted monomer was degassed and removed, and then the olefin-based copolymer was separated from the liquid phase. The obtained olefin-based copolymer was dried in a vacuum dryer at 60 ° C. for 20 hours, and then the monomer composition, the molecular weight, and the vanadium and aluminum contents were measured. Yield of olefin copolymer is 128.9g
The ethylene content was 57.1% by weight, the propylene content was 34.1% by weight, and the 5-ethylidene-2-norbornene content was 8.8% by weight. The number average molecular weight Mn is 231,000 and the weight average molecular weight Mw is 588.
000 and Mw / Mn = 2.5. Vanadium concentration is 8.7 ppm, aluminum concentration is 270 pp
It was m. The olefin-based copolymer in the slurry liquid before purification contained 51.0 ppm of vanadium and 1207 ppm of aluminum.

Example 2 After polymerization was carried out in exactly the same manner as in Example 1, 20 ml of toluene was pressed into the autoclave, 500 ml of ethyl alcohol was immediately added at once, and the contents of the autoclave were kept at 20 ° C. for 30 minutes. Stir vigorously. After the stirring was stopped, the unreacted monomer was degassed and removed, and then the olefin-based copolymer was separated from the liquid phase. After drying the obtained olefin-based copolymer in a vacuum dryer at 60 ° C. for 20 hours, the monomer composition, molecular weight,
And the vanadium and aluminum contents were measured. The yield of the olefin-based copolymer was 129.5 g, the ethylene content was 56.8% by weight, and the propylene content was 3%.
The content of 4.2% by weight and the content of 5-ethylidene-2-norbornene was 9.0% by weight. The number average molecular weight Mn is 24
5,000, the weight average molecular weight Mw was 588,000, and Mw / Mn = 2.4. Vanadium concentration is 1
The concentration was 2.0 ppm and the aluminum concentration was 200 ppm. The olefin-based copolymer in the slurry liquid before purification contained 50.8 ppm of vanadium and 1201 ppm of aluminum.

Example 3 131 g of an olefin-based copolymer was obtained in the same manner as in Example 1 except that ethyl alcohol was replaced with isopropyl alcohol. When the vanadium and aluminum concentrations were measured, the vanadium concentration was 14.0 ppm and the aluminum concentration was 190 p.
It was pm. The olefin-based copolymer before purification contained 50.2 ppm of vanadium and 11% of aluminum.
It was contained at 87 ppm.

[Example 4] 130.5 g of an olefin-based copolymer was obtained in the same manner as in Example 2 except that ethyl alcohol was replaced with isopropyl alcohol. When the vanadium and aluminum contents were measured, the vanadium concentration was 9.5 ppm and the aluminum concentration was 22.
It was 0 ppm. The olefin-based copolymer before purification contained 50.4 ppm of vanadium and 1% of aluminum.
It was contained at 192 ppm.

[Example 5] Polymerization was carried out in the same manner as in Example 1, and then ethyl alcohol was injected at a rate of 4 ml per minute for 50 minutes without adding toluene at all, and 300 ml of ethyl alcohol was temporarily injected. did. Then 2
The contents of the autoclave are vigorously stirred at 0 ° C. for 30 minutes, and then unreacted monomers and the like are degassed and removed,
The olefinic copolymer was separated from the liquid phase. The yield of the olefin-based copolymer after drying was 129.3 g, the vanadium concentration was 6.8 ppm, and the aluminum concentration was 170.
It was ppm. The olefin-based copolymer before purification contained 50.9 ppm of vanadium and 12% of aluminum.
It was contained in an amount of 03 ppm.

Example 6 131.2 g of an olefin-based copolymer was obtained in exactly the same manner as in Example 5 except that ethyl alcohol was replaced by normal butyl alcohol. When vanadium and aluminum concentrations were measured, the vanadium concentration was 9.5 ppm and the aluminum concentration was 22.
It was 0 ppm. The olefin-based copolymer before purification contained 50.4 ppm of vanadium and 1% of aluminum.
It was contained at 192 ppm.

[Embodiment 7] The procedure of Example 5 was repeated except that methyl alcohol was used instead of ethyl alcohol.
31.4 g of an olefin-based copolymer was obtained. When the vanadium and aluminum concentrations were measured, the vanadium concentration was 8.8 ppm and the aluminum concentration was 181 ppm.
Met. The olefin-based copolymer before purification contained 50.1 ppm of vanadium and 1184 p of aluminum.
pm was included.

[Example 8] In the step of adding alcohol, except that initially, normal butyl alcohol was injected into the autoclave at a rate of 4 ml for 1 minute for 50 minutes, and then 300 ml of ethyl alcohol was injected at one time.
In exactly the same manner as in Example 5, 130.8 g of an olefin-based copolymer was obtained. When the vanadium and aluminum concentrations in the olefin-based copolymer were measured, the vanadium concentration was 9.2 ppm and the aluminum concentration was 197 ppm.
Met. The olefin-based copolymer before purification contained vanadium at 50.3 ppm and aluminum at 1189 p.
pm was included.

[Example 9] Polymerization was carried out in exactly the same manner as in Example 1, and ethyl alcohol was added at a rate of 2.5 ml per minute for 40 minutes without adding any toluene, for a total of 100 m.
1 injection. Then, the contents of the autoclave were vigorously stirred at 20 ° C. for 30 minutes, then unreacted monomers and the like were degassed and removed, and the olefin-based copolymer was separated from the liquid phase. Yield of olefinic copolymer after drying is 1
It was 31.1 g, the vanadium concentration was 9.0 ppm, and the aluminum concentration was 192 ppm. In addition, vanadium was added to the olefin-based copolymer before purification at 50.2 pp.
and 1186 ppm of aluminum were contained.

Example 10 Polymerization was carried out in the same manner as in Example 1, and then methyl alcohol was injected into the autoclave at a rate of 4 ml for 1 minute for 25 minutes. Further, 400 ml of methyl alcohol was injected at one time. Immediately after injecting 400 ml of methyl alcohol and immediately lowering the temperature to 0 ° C., the internal pressure of the autoclave dropped from 14 kg / cm ² to 9 kg / cm ² . After stirring the autoclave at 0 ° C. for 30 minutes, unreacted monomers were degassed and removed.
Then, the olefin-based copolymer was separated and recovered from the liquid phase. The yield of the olefinic copolymer after drying is 131.5.
g, the vanadium concentration was 13.5 ppm, and the aluminum concentration was 283 ppm. The olefin-based copolymer before purification contained 50.0 ppm of vanadium and 1183 ppm of aluminum.

Example 11 An autoclave made of stainless steel having an internal volume of 2 liters was charged with 500 g of liquid propylene, 5.76 mmol of diethylaluminum chloride, and 0.1 mmol of diethylzinc. Then, the polymerization temperature was set to 20 ° C., and while stirring the content, ethylene was supplied at a pressure of 3 kg / cm ² , which was lower than the internal pressure of the autoclave,
G While supplying at a high pressure, a solution of 0.129 mmol of vanadium triacetylacetonate dissolved in 8 cc of toluene was supplied to initiate polymerization. The polymerization was carried out for 45 minutes. As the activator, a mixture of ethyl monochloromalonate and ethyl dichloromalonate mixed in a molar ratio of 3: 7 was used, and 0.26 mmol of this mixture was supplied to the autoclave as a solution dissolved in 6 ml of toluene. The toluene solution of vanadium triacetylacetonate and the activator was continuously supplied from the beginning to the end of the polymerization. The supply start time of these toluene solutions was used as the polymerization start time, and the supply end time was used as the polymerization end time.
After 45 minutes, pressurize 20 ml of cyclohexane into the autoclave and immediately add 4 ml of methyl alcohol for 1 minute.
Was pumped for 50 minutes. Furthermore, 300 ml of ethyl alcohol was injected, and the contents of the autoclave were vigorously stirred at 20 ° C. for 30 minutes. After stirring the content, unreacted monomers were degassed and removed, and then the olefin copolymer (ethylene-propylene rubber) was separated from the liquid phase. The obtained olefin-based copolymer was dried in a vacuum dryer at 60 ° C. for 20 hours, and then the monomer composition, the molecular weight, and the vanadium and aluminum contents were measured. The yield of the olefinic copolymer was 146.0 g, the ethylene content was 59.8% by weight, and the propylene content was 40.
It was 2% by weight. The number average molecular weight Mn is 310,00.
0, weight average molecular weight Mw is 972,000, Mw
/Mn=3.1. Vanadium concentration is 6.5pp
m and the aluminum concentration were 175 ppm. The olefin-based copolymer in the slurry liquid before purification contained vanadium at 45.1 ppm and aluminum at 1065 pp.
m was included.

Claims (1)

[Claims] 1. A method for removing a catalyst component from an elastomeric olefin-based copolymer obtained by suspension polymerization of ethylene and propylene or ethylene, propylene and a non-conjugated diene hydrocarbon in a hydrocarbon. Then, (a) an organic solvent having a solubility parameter in the range of 7.3 to 9.5 is added to the polymerization system before, during, and / or after the polymerization, and (b) the polymerization is performed. A method for purifying an elastomeric olefin-based copolymer, which comprises adding 0.2 to 100 parts by weight of alcohol to 1 part by weight of the olefin-based copolymer at a later point in time in the polymerization system.