JP3022902B2 - Deashing method of elastomeric olefin copolymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention demineralizes an elastomeric olefin copolymer such as ethylene-propylene rubber or ethylene-propylene-diene terpolymer obtained by suspension polymerization in liquid propylene. About the method.

[0002]

2. Description of the Related Art Ethylene propylene rubber and ethylene propylene
Elastomer-like olefin copolymers such as propylene / diene terpolymers are generally prepared by using a transition metal compound such as a trivalent or pentavalent vanadium compound and an organoaluminum compound as catalysts to prepare ethylene and propylene or ethylene. And propylene and a non-conjugated diene-based hydrocarbon. As industrial processes, 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.

[0003] The solution polymerization method has an advantage that almost no blockage occurs in the reactor because the olefin copolymer produced during the polymerization hardly precipitates. In addition, since the polymerization pressure is low, the design, manufacture and operation of the reactor are easy, and the transfer of the solution after the polymerization is easy. Furthermore, since the deashing operation is extremely easy, an olefin copolymer having an extremely low content of catalyst residues can be easily obtained. For this reason, conventionally, the solution polymerization method has been mainly performed.

However, in the solution polymerization method, since the viscosity of the polymerization solution sharply increases as the polymerization proceeds, the concentration of the olefin polymer is limited to about 7 to 10%.
The molecular weight could not be increased. Also, it was difficult to remove the heat of polymerization. Further, there is a problem that a deashing step, a coagulation step, a solvent recovery step and the like are required, and the process becomes complicated. For this reason, in recent years, it has been studied to adopt a suspension polymerization method that does not have such a disadvantage.

[0005]

[Problem to be Solved] In the suspension polymerization method, the polymerization proceeds in a state of a slurry liquid in which an olefin-based copolymer is suspended in a liquid state in liquid propylene, so that the polymerization system does not have high viscosity. . Therefore, there is a possibility that the concentration and molecular weight of the olefin-based copolymer can be increased as compared with the solution method. Also, the removal of heat of polymerization is extremely easy due to the latent heat of vaporization of propylene. Further, it is easy to control the monomer composition ratio in the olefin 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 demineralization after polymerization. However, when the vanadium content in the olefin-based copolymer is high, the olefin-based copolymer may be colored yellow or brown or its physical properties may be reduced. For this reason, it is strongly required that the vanadium content be low, and in particular, in recent years, an extremely low content of 5 ppm or less has been demanded.

[0008] 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. It has been studied to reduce the vanadium content of the olefin-based copolymer itself. At the same time, it was studied to improve the demineralization step so that vanadium in the olefin-based copolymer could be more effectively removed. Conventionally studied methods of demineralization include, for example, adding a 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 to the slurry obtained in the polymerization step, and then adding There is a method of mixing an organic solvent such as toluene (Japanese Patent Publication No. 46-5156). In addition, a method of adding an alcohol, an aqueous solution of caustic soda, or an aqueous solution of tartaric acid to the slurry at a pressure higher than the polymerization pressure and decalcifying the slurry (Japanese Patent Publication No. 48-16063) was also studied. Further, a method of adding polyether diamine or polyether monoamine to the slurry after polymerization and washing with water (Japanese Patent Publication No. 46-6985), or a method of adding a good solvent and a surfactant and then adding water. (JP-A-60-69112) was also studied.

However, even with these methods, it has been difficult to obtain an olefin copolymer having an extremely low vanadium content of 5 ppm.

It is an object of the present invention to provide a method for demineralizing an olefin copolymer having a very low vanadium content of 5 ppm or less.

[0011]

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

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

The amount of the good solvent to be added is preferably in the range of 0.01 to 0.40 by weight relative to the unreacted liquid propylene, and more 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, so that the catalyst residue is not sufficiently extracted. On the other hand, if it is more than 0.40, the produced olefin polymer dissolves in the added good solvent, so that there is a problem that the viscosity of the slurry liquid increases.

On the other hand, the amount of hydrogen peroxide to be added is 0.01 to 5 per mole of the vanadium compound used as a catalyst.
000 mol, preferably 0.1 to 10 mol
It is particularly preferred to be in the range of 00 mol. If the amount of hydrogen peroxide is less than 0.01 mol per mol of the vanadium compound, the vanadium compound is not sufficiently oxidized, which is not preferable. On the other hand, the addition amount of hydrogen peroxide is 50
If it is larger than 00 mol, the olefin-based copolymer itself may be oxidized, which is not preferable.

The good solvent and hydrogen peroxide can be added simultaneously. In this case, the good solvent and hydrogen peroxide may be added separately, or may be added in advance as a mixed solution.
Alternatively, the good solvent may be added first, and then the hydrogen peroxide may be added, or may be added in the reverse order. 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 ethers, ketones, esters and the like 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,
Examples include methyl ethyl ketone, diethyl ether, dipropyl ether, ethyl acetate, acetic acid, chloroform, tetrachloroethane and the like. However, a solvent having a solubility parameter smaller than 7.3 is not preferable because a swelling effect of the polymer is small, and a solvent larger than 9.5 is not preferable because the catalyst removing effect is small.

As a second step, water or an alkaline aqueous solution is added to the slurry 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 amount of the water or the aqueous alkali solution is preferably in the range of 0.01 to 10% by weight based on the weight of the olefin copolymer, and the temperature at the time of addition / stirring is −10 to 60 ° C. Is preferable. In order to separate the aqueous phase, for example, a method such as standing is possible. At this time, the aqueous phase separates downward, and the slurry of the olefin copolymer particles separates upward.

As the water or alkaline solution, those having a pH of 7.1 to 12 are used. Examples of such an aqueous solution include an aqueous caustic soda solution, an aqueous caustic potassium solution, and an aqueous ammonia solution. A medium to acidic aqueous solution having a pH of less than 7.1 or an alkaline aqueous solution having a pH of more than 12 is not preferable because the catalyst residue hardly dissolves.

[0019]

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

[0020]

Example 1 A 2-liter stainless steel autoclave was charged with 500 g of liquid propylene and 5-ethylidene-
14 ml of 2-norbornene, 3.0 mmol of diethylaluminum chloride, and 0.2 mmol of diethylzinc
l was charged. Next, the polymerization temperature was set at 20 ° C.
While stirring the contents, while supplying ethylene at a pressure 2 kg / cm ² and G higher than the internal pressure of the autoclave,
A solution prepared by dissolving 0.05 mmol of vanadium triacetylacetonate in 4 cc of toluene was injected under pressure to initiate polymerization. The polymerization was carried out for 20 minutes. A mixture of ethyl monochloromalonate and ethyl dichloromalonate in a molar ratio of 2: 8 was used as an activator, and 0.12 mmol of this mixture was dissolved in toluene to make a 3 ml solution. 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 following formula. First, 40 ml of toluene as a good solvent was added to this slurry solution, and then 0.1 ml of a 30% strength aqueous hydrogen peroxide solution was added.
Stir vigorously for minutes. Next, 500 ml of an aqueous solution of caustic soda having a pH of 10 was added thereto, the mixture was stirred for 30 minutes, and then allowed to stand for 30 minutes to separate an aqueous phase from the slurry.
Unreacted monomers were removed from the slurry liquid from which the aqueous phase was separated by degassing, and a small amount of remaining toluene and the like was removed by a vacuum dryer. The resulting 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, the weight average molecular weight Mw is 614,000,
/Mn=2.5. Vanadium content is 3.8p
pm, and the aluminum content was 261 ppm.
The copolymer in the slurry before the deashing had a vanadium content of 19.9 ppm and an aluminum content of 633 p.
pm.

[0021]

Example 2 A 2-liter stainless steel autoclave was charged with 500 g of liquid propylene and 5-ethylidene-
12 ml of 2-norbornene, 2.5 mmol of diethylaluminum chloride, and 0.1 mmol of diethylzinc
l was charged. Then, the polymerization temperature was set at 25 ° C.
While stirring the contents, while supplying ethylene at a pressure 2 kg / cm ² and G higher than the internal pressure of the autoclave,
A solution obtained by dissolving 0.036 mmol of vanadium triacetylacetonate in 3 cc of toluene was injected under pressure to initiate polymerization. The polymerization was performed for 30 minutes. As the activator, a mixture of ethyl monochloromalonate and nityldichloromalonate mixed at a molar ratio of 1: 9 was used, and a solution obtained by dissolving 0.18 mmol of this mixture in toluene to make 5 ml was completed from the start of polymerization. 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 is added to the slurry, and then 0.2 ml of a 30% hydrogen peroxide aqueous solution.
Was added and stirred vigorously at 20 ° C. for 10 minutes. Then p
500 ml of an aqueous solution of H10.5 caustic soda was added, and 3
The mixture was stirred for 0 minutes, and then allowed to stand for 30 minutes to separate an aqueous phase from the slurry. Unreacted monomers were removed from the slurry liquid from which the aqueous phase was separated by degassing, and a small amount of remaining 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.
3,000, and Mw / Mn = 2.3. Vanadium content is 2.6 ppm, aluminum content is 1
It was 92 ppm. In addition, 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 In a stainless steel autoclave having a capacity of 2 liters, 500 g of liquid propylene, 10 ml of dicyclopentadiene, and 2.8 of diethylaluminum chloride.
mmol and 0.1 mmol of diethyl zinc. Then, the polymerization temperature was set to 25 ° C., and while stirring the contents, ethylene was added to the autoclave at an internal pressure of 2 ° C.
kg / cm ² , G
A solution in which 4 mmol of vanadium triacetylacetonate was dissolved in 4 cc of toluene was injected under pressure to initiate polymerization.
The polymerization was performed for 25 minutes. As the activator, a mixture obtained by mixing ethyl monochloromalonate and ethyl dichloromalonate in a molar ratio of 1: 9 was used.
A solution prepared by dissolving mol in toluene to make 5 ml 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 the slurry, and then 0.3 ml of a 30% aqueous solution of hydrogen peroxide was added, followed by vigorous stirring at 25 ° C. for 10 minutes. Then, 500 ml of an aqueous solution of potassium hydroxide having a pH of 10.5 was added, and the mixture was stirred for 20 minutes.
Then, the mixture was allowed to stand for 30 minutes to separate an aqueous phase from the slurry liquid. From the slurry liquid from which the aqueous phase was separated, unreacted monomers were removed by degassing, and a small amount of remaining xylene and the like was removed by a vacuum dryer. The resulting copolymer had an ethylene content of 68.8% by weight and a propylene content of 25.8.
% By weight, the content of dicyclopentadiene is 5.4% by weight
Met. The number average molecular weight Mn is 295,000, the weight average molecular weight Mw is 710,000, and Mw / Mn =
2.4. The vanadium content was 3.1 ppm and the aluminum content was 235 ppm. The copolymer in the slurry before the deashing had a vanadium content of 1
8.2 ppm, aluminum content was 518 ppm.

[0023]

Comparative Example 1 In the same manner as in Example 1, ethylene, propylene and 5-ethylidene-2-norbornene were subjected to suspension polymerization in liquid propylene, and the slurry concentration was 27.7% by weight.
Was obtained. To 599 g of this slurry liquid, 40 ml of toluene was added as a good solvent,
The mixture was vigorously stirred and mixed for 0 minutes. Then, 500 ml of aqueous sodium hydroxide solution of pH 10 was added and stirred for 30 minutes. Thereafter, the mixture was allowed to stand for 30 minutes, and the aqueous phase was separated. Unreacted monomers were removed from the slurry liquid from which the aqueous phase was separated by degassing, and a small amount of remaining toluene and the like was removed by a vacuum dryer. The resulting copolymer had an ethylene content of 70.9.
% By weight, 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 had a vanadium content of 19.6 ppm and an aluminum content of 623 ppm.
Met.

[0024]

Comparative Example 2 Ethylene, propylene and dicyclopentadiene were subjected to suspension polymerization in liquid propylene in the same manner as in Example 3 to obtain a slurry having a slurry concentration of 31.6% by weight. Concentration 30% to 608 g of this slurry liquid
0.3 ml of a hydrogen peroxide solution, and vigorously stirred at 25 ° C. for 10 minutes.
00 ml was added and the mixture was stirred for 20 minutes and then allowed to stand for 30 minutes to separate the aqueous phase. From the slurry separated from the aqueous phase,
Unreacted monomers were removed by degassing, 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,
Mw / Mn = 2.5. Vanadium content is 8.
It was as high as 3 ppm. Aluminum content is 255pp
m. Incidentally, the copolymer in the slurry liquid before deashing,
The vanadium content was 18.2 ppm and the aluminum content was 518 ppm.

[0025]

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

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-214705 (JP, A) JP-A-4-216803 (JP, A) JP-A-48-37482 (JP, A) JP-A-1- 149804 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08F 6/08

Claims (1)

(57) [Claims] 1. An elastomeric olefin copolymer obtained by suspension polymerization of ethylene and propylene or ethylene and propylene and a non-conjugated diene hydrocarbon using a vanadium compound and an organoaluminum compound as catalysts. (A) mixing a good solvent and hydrogen peroxide into a polymerization system, and then (b) adding water or an alkaline aqueous solution to remove the catalyst residue in the elastomeric olefin-based copolymer into an aqueous phase. A method for deashing an elastomeric olefin copolymer to be extracted into water.