JPH05320220A - Deashing of elastomeric olefin copolymer - Google Patents

Abstract

PURPOSE:To provide a deashing process for effectively removing a catalyst component especially a vanadium compound in producing an ethylene/propylene rubber or an ethylene/propylene/diene terpolymer by suspension-polymerizing in liquid propylene. CONSTITUTION:Hydrogen peroxide and a good solvent are added to the suspension obtained in the polymerization step, and an aqueous alkali solution (of a pH of 7.1-12) is added thereto to decompose catalyst residues and to extract them into the water phase.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention deashes an elastomeric olefinic copolymer such as ethylene / propylene rubber or ethylene / propylene / diene terpolymer obtained by suspension polymerization in liquid propylene. Regarding the method.

[0002]

[Prior Art] ethylene / propylene rubber and ethylene /
Elastomeric olefinic copolymers such as propylene / diene terpolymers are generally ethylene and propylene, or ethylene, using a transition metal compound such as a trivalent or pentavalent vanadium compound and an organoaluminum compound as a catalyst. And propylene with non-conjugated diene hydrocarbons. 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 that the clogging in the reactor hardly occurs because the olefin copolymer produced during the polymerization hardly precipitates. Further, since the polymerization pressure is low, the reactor is easy to design, manufacture and operate, and the solution can be easily transferred after the polymerization. Furthermore, 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. Therefore, conventionally, the solution polymerization method has been mainly used.

However, in the solution polymerization method, the viscosity of the polymerization solution rapidly increases as the polymerization progresses, 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. Furthermore, there is a problem that the process becomes complicated because a deashing process, a coagulation 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. In addition, the latent heat of vaporization of propylene makes it extremely easy to remove the heat of polymerization. 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. However, when the vanadium content in the olefin-based copolymer is high, the olefin-based copolymer is colored yellow or brown or the physical properties are deteriorated. Therefore, it is strongly demanded that the vanadium content be low, and in particular, in recent years, an extremely low content of 5 ppm or less has been demanded.

In order to solve the above-mentioned problems in the suspension polymerization method, an activator such as ethyl monochloromalonate or ethyl dichloromalonate is added to the polymerization system to improve the activity of the catalyst, thereby forming it in the polymerization step. It was investigated to reduce the vanadium content of the olefin copolymer itself. At the same time, it was also studied to improve the deashing process so that vanadium in the olefin-based copolymer can be removed more effectively. As a deashing method conventionally studied, for example, hydrochloric acid or 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 are added to the slurry obtained in the polymerization step, and then this is added There is a method of mixing an organic solvent such as toluene (Japanese Patent Publication No. 46-5156). In addition, a method of adding alcohol, an aqueous solution of caustic soda, an aqueous solution of tartaric acid or the like to the slurry at a pressure higher than the polymerization pressure for deashing (Japanese Patent Publication No. 48-16063) was also studied. Furthermore, a method of adding polyether diamine or polyether monoamine etc. to the slurry after polymerization and then washing with water (Japanese Patent Publication No. 46-9985), or a method of adding water after adding a good solvent and a surfactant. (JP-A-60-69112) was also examined.

However, even by these methods, it was difficult to obtain an olefin-based copolymer having a vanadium content as low as 5 ppm.

An object of the present invention is to provide a deashing method by which an olefinic copolymer having an extremely low vanadium content of 5 ppm or less can be easily obtained.

[0011]

[Technical Means for Solving the Problems] The deashing method of the present invention comprises:
A method for deashing an elastomeric olefinic copolymer obtained by suspension polymerization of ethylene and propylene or ethylene, propylene and a non-conjugated diene hydrocarbon using a vanadium compound and an organoaluminum compound as a catalyst. First, a good solvent and hydrogen peroxide are mixed with the slurry liquid obtained in the polymerization step, and then water or an alkaline aqueous solution is added to extract the catalyst residue in the elastomeric olefin-based copolymer into the aqueous phase. That is. Hereinafter, the present invention will be described in more detail.

First, in the slurry liquid obtained in the polymerization step,
As a first step, adding a good solvent and hydrogen peroxide, stirring,
Mix. At this stage, the olefin-based copolymer particles in the slurry liquid are swollen by the good solvent added, and the vanadium compound in the catalyst residue contained in the particles is oxidized by hydrogen peroxide, resulting in a high vanadium valence state. It is presumed that it becomes a highly water-soluble state.

The amount of the good solvent added is preferably in the range of 0.01 to 0.40 by weight ratio to the unreacted liquid propylene, and preferably in the range of 0.02 to 0.30. Particularly preferred. If the amount of the good solvent with respect to the unreacted liquid propylene is less than 0.01, the olefin-based copolymer does not swell sufficiently and the catalyst residue is not sufficiently extracted. On the other hand, when the amount is more than 0.40, the generated olefin polymer is dissolved in the good solvent added, and there is a problem that the viscosity of the slurry liquid increases.

On the other hand, the amount of hydrogen peroxide added is 0.01 to 5 relative to 1 mol of the vanadium compound used as the catalyst.
The amount is preferably in the range of 000 mol, 0.1-10
It is particularly preferable to set it in the range of 00 mol. If the amount of hydrogen peroxide added is less than 0.01 mol per mol of the vanadium compound, the vanadium compound will not be sufficiently oxidized, which is not preferable. On the other hand, the amount of hydrogen peroxide added is 50
When it is more than 00 mol, the olefinic copolymer itself produced may be oxidized, which is not preferable.

The good solvent and hydrogen peroxide can be added at the same time. In this case, the good solvent and hydrogen peroxide may be added separately, or may be added as a mixed solution in advance.
Further, the good solvent may be added first, and then the hydrogen peroxide may be added, or vice versa. However, in any of these methods, hydrogen peroxide is preferably added as an aqueous solution for safety reasons.

As the good solvent, those having a solubility parameter of 7.3 to 9.5 are used. 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. However, 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, which is not preferable.

In the second step, water or an alkaline aqueous solution is added to the slurry liquid containing the good solvent and hydrogen peroxide, and the mixture is stirred to extract the catalyst residue in the olefin copolymer particles into the aqueous phase. The addition amount of water or an aqueous alkali solution is preferably in the range of 0.01 to 10 weight with respect to 1 weight of the olefin copolymer, and the temperature during addition and stirring is -10 to 60 ° C. Is preferred. In order to separate the aqueous phase, for example, a method of leaving it stationary is possible. At this time, the aqueous phase separates downward and the slurry of olefin copolymer particles separates upward.

Water or an alkaline solution having a pH of 7.1 to 12 is used. Examples of such a material include caustic soda aqueous solution, caustic potash aqueous solution, and ammonia aqueous solution. A medium to acidic aqueous solution having a pH of less than 7.1 and an alkaline aqueous solution having a pH of more than 12 are not preferable because the catalyst residue is difficult to dissolve.

[0019]

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

[0020]

Example 1 500 g of liquid propylene and 5-ethylidene were placed in a stainless steel autoclave having an internal volume of 2 liters.
2-norbornene 14 ml, diethyl aluminum chloride 3.0 mmol, and diethyl zinc 0.2 mmo
I was prepared. Then set the polymerization temperature to 20 ° C.,
While stirring the contents, while supplying ethylene at a pressure 2 kg / cm ² , G higher than the internal pressure of the autoclave,
A solution of 0.05 mmol of vanadium triacetylacetonate dissolved in 4 cc of toluene was press-fitted to initiate polymerization. The polymerization was carried out for 20 minutes. As the activator, a mixture of ethyl monochloromalonate and ethyl dichloromalonate in a molar ratio of 2: 8 was used, and 0.12 mmol of this mixture was dissolved in toluene to 3 ml to complete the solution from the start of polymerization. Added continuously over time. After 20 minutes, 597 g of a slurry liquid was obtained.
The slurry concentration of this slurry liquid was 27.3% by weight. The slurry concentration is It was calculated by the formula. First, 40 ml of toluene as a good solvent was added to this slurry liquid, and then 0.1 ml of a 30% hydrogen peroxide aqueous solution was added thereto, and the mixture was stirred at 20 ° C. for 10 minutes.
Stir vigorously for a minute. Next, 500 ml of a caustic soda aqueous solution having a pH of 10 was added, the mixture was stirred for 30 minutes, and then allowed to stand for 30 minutes to separate an aqueous phase from the slurry liquid.
Unreacted monomers were degassed and removed from the slurry liquid from which the aqueous phase was separated, and a small amount of residual toluene and the like was removed by a vacuum dryer. The obtained copolymer had an ethylene content of 70.5% by weight, a propylene content of 24.1% by weight, and a 5-ethylidene-2-norbornene content of 5.
It was 4% by weight. The number average molecular weight Mn is 243,00
0, weight average molecular weight Mw is 614,000, Mw
/Mn=2.5. Vanadium content is 3.8p
The pm and aluminum contents were 261 ppm.
The copolymer in the slurry liquid before deashing had a vanadium content of 19.9 ppm and an aluminum content of 633 p.
It was pm.

[0021]

Example 2 500 g of liquid propylene and 5-ethylidene were placed in a stainless steel autoclave having an internal volume of 2 liters.
2-norbornene 12 ml, diethyl aluminum chloride 2.5 mmol, and diethyl zinc 0.1 mmo
I was prepared. Then set the polymerization temperature to 25 ° C.,
While stirring the contents, while supplying ethylene at a pressure 2 kg / cm ² , G higher than the internal pressure of the autoclave,
A solution prepared by dissolving 0.036 mmol of vanadium triacetylacetonate in 3 cc of toluene was press-fitted to initiate polymerization. The polymerization was carried out for 30 minutes. As the activator, a mixture of ethyl monochloromalonate and nityl dichloromalonate was mixed at a molar ratio of 1: 9, and 0.18 mmol of this mixture was dissolved in toluene to make a solution of 5 ml. Added continuously over time. After 30 minutes, 597 g of a slurry liquid was obtained. The slurry concentration in the slurry liquid was 27.8% by weight.
The slurry concentration was calculated in the same manner as in Example 1.
First, 60 ml of cyclohexane was added to this slurry liquid, and then 0.2 ml of a 30% hydrogen peroxide aqueous solution.
Was added and the mixture was vigorously stirred at 20 ° C. for 10 minutes. Then p
Add 500 ml of H10.5 caustic soda solution and add 3
The mixture was stirred for 0 minute and then left standing for 30 minutes to separate an aqueous phase from the slurry liquid. Unreacted monomers were degassed and removed from the slurry liquid from which the aqueous phase was separated, and a small amount of residual toluene and the like was removed by a vacuum dryer. The obtained copolymer had an ethylene content of 69.6% by weight, a propylene content of 25.2% by weight, and a 5-ethylidene-2-norbornene content of 5.2% by weight. The number average molecular weight Mn is 277,000 and the weight average molecular weight Mw is 64.
It was 3,000 and Mw / Mn = 2.3. Vanadium content is 2.6 ppm, aluminum content is 1
It was 92 ppm. The copolymer in the slurry liquid before deashing had a vanadium content of 14.1 ppm and an aluminum content of 519 ppm.

[0022]

Example 3 500 g of liquid propylene, 10 ml of dicyclopentadiene, and diethylaluminum chloride 2.8 were placed in a stainless steel autoclave having an internal volume of 2 liters.
and 0.1 mmol of diethyl zinc were charged. Then, the polymerization temperature was set to 25 ° C., and while stirring the content, ethylene was added to the autoclave at an internal pressure of 2
kg / cm ² , G While feeding at a high pressure, 0.052
A solution of mmol vanadium triacetylacetonate dissolved in 4 cc of toluene was press-fitted to initiate polymerization.
The polymerization was carried out for 25 minutes. As an activator, a mixture of ethyl monochloromalonate and ethyl dichloromalonate in a molar ratio of 1: 9 was used.
A solution having 5 mol dissolved in toluene was continuously added from the start to the end of the polymerization. After 25 minutes, 608 g of a slurry liquid was obtained. The slurry concentration in the slurry liquid was 31.6% by weight. The slurry concentration was calculated in the same manner as in Example 1. First, 50 ml of xylene was added to this slurry liquid, and then 0.3 ml of a 30% hydrogen peroxide aqueous solution was added thereto, and the mixture was vigorously stirred at 25 ° C. for 10 minutes. Then, add 500 ml of a caustic potash aqueous solution having a pH of 10.5, stir for 20 minutes,
Then, the mixture was allowed to stand for 30 minutes to separate the aqueous phase from the slurry liquid. Unreacted monomers were degassed and removed from the slurry liquid from which the aqueous phase was separated, and a small amount of residual xylene and the like was removed by a vacuum dryer. The obtained copolymer had an ethylene content of 68.8% by weight and a propylene content of 25.8.
Wt%, dicyclopentadiene content 5.4 wt%
Met. The number average molecular weight Mn is 295,000, the weight average molecular weight Mw is 710,000, and Mw / Mn =
It was 2.4. The vanadium content was 3.1 ppm and the aluminum content was 235 ppm. The copolymer in the slurry liquid before deashing has a vanadium content of 1
The content was 8.2 ppm and the aluminum content was 518 ppm.

[0023]

Comparative Example 1 Ethylene, propylene, and 5-ethylidene-2-norbornene were suspension-polymerized in liquid propylene in the same manner as in Example 1 to obtain a slurry concentration of 27.7% by weight.
A slurry liquid of was obtained. To 599 g of this slurry liquid, 40 ml of toluene was added as a good solvent, and the mixture was stirred at 20 ° C
The mixture was stirred vigorously for 0 minutes. Next, 500 ml of a caustic soda aqueous solution having a pH of 10 was added and stirred for 30 minutes. Then, the mixture was allowed to stand for 30 minutes to separate the aqueous phase. Unreacted monomers were degassed and removed from the slurry liquid from which the aqueous phase was separated, and a small amount of residual toluene and the like was removed by a vacuum dryer. The obtained copolymer has an ethylene content of 70.9.
%, The propylene content was 24.0% by weight, and the content of 5-ethylidene-2-norbornene was 5.1% by weight. The number average molecular weight Mn is 248,000, the weight average molecular weight Mw is 625,000, and Mw / Mn = 2.5.
Met. The vanadium content was as high as 7.2 ppm. The aluminum content was 395 ppm. still,
The copolymer in the slurry liquid before deashing has a vanadium content of 19.6 ppm and an aluminum content of 623 ppm.
Met.

[0024]

Comparative Example 2 Ethylene, propylene and dicyclopentadiene were suspension polymerized in liquid propylene in the same manner as in Example 3 to obtain a slurry liquid having a slurry concentration of 31.6% by weight. Concentration 30% to 608 g of this slurry liquid
Hydrogen peroxide solution (0.3 ml) was added and the mixture was vigorously stirred at 25 ° C. for 10 minutes, and then a caustic soda solution having a pH of 10.5 was added.
00 ml was added and the mixture was stirred for 20 minutes and then left standing for 30 minutes to separate the aqueous phase. From the slurry liquid that separated the aqueous phase,
Unreacted monomers were degassed and removed, and a small amount of remaining xylene and the like was removed by a vacuum dryer. The obtained copolymer had an ethylene content of 68.5% by weight, a propylene content of 26.1% by weight, and a dicyclopentadiene content of 5.4% by weight. The number average molecular weight Mn is 285.
000, the weight average molecular weight Mw is 721,000,
It was Mw / Mn = 2.5. Vanadium content is 8.
It was as high as 3 ppm. Aluminum content is 255pp
It was m. The copolymer in the slurry liquid before deashing is
The vanadium content was 18.2 ppm and the aluminum content was 518 ppm.

[0025]

By using the deashing method of the present invention, the catalyst residue can be effectively removed from the particulate olefinic copolymer produced in the suspension polymerization method. An olefin-based copolymer having an extremely low vanadium content of 5 ppm or less can be easily obtained.

Claims (1)

[Claims] 1. An elastomeric olefinic copolymer obtained by suspension polymerization of ethylene and propylene or ethylene, propylene and a non-conjugated diene hydrocarbon using a vanadium compound and an organoaluminum compound as a catalyst. In the method, (a) a good solvent and hydrogen peroxide are mixed in the polymerization system, and then (b) water or an alkaline aqueous solution is added to remove the catalyst residue in the elastomeric olefin copolymer into an aqueous phase. Extraction method for elastomeric olefinic copolymer.