JPH0454684B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing synthetic rubber with less catalyst residue. Synthetic rubber can be produced by producing synthetic rubber using a catalyst containing a transition metal compound and an organoaluminum compound as the main components, a so-called Ziegler catalyst, removing the solvent by steam stripping, and recovering the polymer. It is widely practiced. In this production method, the polymer after polymerization comes into contact with water during the steam stripping process, so some of the water-soluble catalyst residue is transferred to water, but a considerable amount of catalyst is usually present in the synthetic rubber. Residues are visible. It is known that a large amount of transition metal catalyst residue causes discoloration of synthetic rubber and accelerates rubber aging. It is believed that a large amount of residual halogen, especially chlorine, causes corrosion of metal materials such as equipment and instruments that synthetic rubber comes into contact with, particularly iron, iron alloys, and aluminum. The present inventors have conducted intensive research on a method for producing synthetic rubber with less catalyst residue, and have found that when a specific compound is used as a polymerization terminator immediately after polymerization using a Ziegler catalyst, it does not perform its original function as a polymerization terminator. That is, the inventors have discovered that the catalyst residue in the obtained synthetic rubber can be significantly reduced by stopping the progress of polymerization and preventing the increase in the molecular weight of the polymer (preventing gel formation), and have completed the present invention. The present invention is used as a polymerization terminator in a synthetic rubber production method in which synthetic rubber is produced using a polymerization catalyst mainly composed of a transition metal compound and an organoaluminum compound, and the polymer is recovered by removing the solvent by steam stripping. After stopping the polymerization using at least one compound selected from alkyl ester derivatives of polyethylene glycol, cyclic ester compounds, and pentaerythritol tetraester, the amount of 0.05 to 1% per part of the polymer solution is
Add 4 parts of water to emulsify the polymer solution, then
Furthermore, the process for producing synthetic rubber is characterized by adding 0.2 to 2.0 parts of water to 1 part of the polymer solution, inverting the phase, and desolventizing the separated polymer solution by steam stripping. be. In particular, the present invention relates to a method for producing non-corrosive synthetic rubber suitable as a raw material for rubber products used in materials such as metals, which are susceptible to deterioration due to trace components in synthetic rubber. Known transition metal compounds used as polymerization catalysts for synthetic rubber include, for example, nickel, cobalt, vanadium, niobium, and lanthanum. Known organic aluminum compounds include, for example, trialkylaluminum, dialkylaluminum monochloride, alkylaluminum sesquichloride, alkylaluminum dichloride, and the like. Synthetic rubbers include polybutadiene, polyisoprene, ethylene-propylene synthetic rubber (ethylene-α-olefin copolymer, ethylene-propylene rubber EPM, and ethylene-propylene rubber).
Diene rubber (EPDM) etc. are known, and these are usually removed by steam stripping to remove the solvent and recover the polymer. In the case of ethylene-propylene synthetic rubber, aliphatic hydrocarbons, aromatic hydrocarbons or halogenated hydrocarbons are used as the reaction medium, and transition metals such as vanadium oxytrichloride and vanadium tetrachloride and their alcohols (carbon number 1- 12) Using a combination catalyst of a soluble vanadium compound such as a modified compound and an organometallic compound such as an organoaluminium compound such as ethylaluminum sesquichloride, diethylaluminum monochloride, ethylaluminum dichloride, trialkylaluminum and mixtures of these organoaluminum compounds. , polymerization temperature -30~90℃ preferably 10~60℃
It is produced by polymerization at a temperature of 0.degree. C. and a polymerization pressure of 0 to 20 kg/ ^cm.sup.2 . Propylene is most suitable as the α-olefin, but 1-butene, 1-pentene, 1-hexene, etc. may also be used. The non-conjugated diene component is 5-ethylidene-2-norbornene,
Examples include 5-alkylidene-2-norbornene such as 5-isopropenyl-2-norbornene and 5-propenyl-2-norbornene, dicyclopentadiene, and 1,4-hexadiene. Usually the ratio of ethylene and α-olefin in the copolymer is 90/10 to 30/70 (weight ratio), preferably 85/15 to
The weight ratio is 40/60. The diene component is about 0.1 to 8 mol%. When the polymerization reaches a predetermined polymer concentration, a polymerization terminator specified in the present invention is added to the polymerization reaction solution, and the mixture is stirred to stop the polymerization. Alkyl ester derivatives of polyethylene glycol

[Formula] group (in the formula, R is a C ₁ to _{C 20} alkyl group, n is an integer of 3 to 200), examples of which include polyoxyethylene monoalkylate, polyoxyethylene sorbitate tetraolefinate, etc. Among these, polyoxyethylene sorbitate tetraoleate is particularly preferred. Butyrolactone as a cyclic ester compound,
γ-valerolactone, γ-caprylolactone, γ
-nonalactone, γ-stearolactone, β-propiolactone, δ-valerolactone, δ-caprolactone, ε-caprolactone, coumarin, and the like. Examples of the pentaerythritol tetraester include pentaerythritol tetraacetate, pentaerythritol tetraoctanoate, pentaerythritol tetrastearate, pentaerythritol diacetyl distearate, and pentaerythritol monoacetyl trioctanoate. The amount of these compounds added is 0.01 to the polymer.
The amount is from 0.1 to 1% by weight, preferably from 0.1 to 1% by weight. After adding the polymerization terminator of the present invention, the solvent is removed by steam stripping according to a conventional method, but in this post-treatment, the molecular weight of the polymer does not increase and the polymer with low catalyst residue is produced. is obtained. In a more preferred embodiment, after adding the polymerization terminator, 0.05 to 0.4 parts of water is added to 1 part of the polymer solution;
Preferably, 0.1 to 0.3 parts of water is added and thoroughly stirred to emulsify. In the water, a nonionic surfactant such as polyoxyethylene alkyl ether type, polyethylene alkyl phenol ether type, sorbitan ester type, polyoxyethylene sorbitan ester type, or polypropylene glycol is added in an amount of 0.005 to 0.3% by weight based on the water. Preferably
It is preferable to add 0.01 to 0.1% by weight. After the polymer solution has been emulsified in this manner, 0.2 to 2.0 parts of water is added to 1 part of the polymer solution, thoroughly stirred, phase inverted, and left to stand to separate the polymer solution and water. By steam-stripping the polymer solution thus obtained according to a conventional method, a polymer with less catalyst residue can be obtained without increasing the molecular weight. The present invention will be specifically explained with reference to Examples. Reference Example 1 In a continuous polymerization vessel of 5, n-hexane 3/hr, vanadium oxytrichloride 2.0 mmol/hr, ethylaluminum sesquichloride 9.1 mmol/hr,
26 g/hr of 5-ethylidene-2-norbornene, 300 g/hr of ethylene, and 860 g/hr of propylene were continuously fed, and hydrogen was fed so that the hydrogen content in the gas phase of the polymerization reactor was maintained at 20%. The liquid residence time is 40 minutes35
The reaction was carried out at a temperature of 7.5 kgG/cm ² . The concentration of ethylene copolymer in the effluent was 98 g/.
This copolymer liquid was added to polyoxyethylene monostearate with n≒5 (trade name: Nonion S, manufactured by NOF Corporation).
-2) was added in an amount of 0.5g per 1 part of the copolymer solution.
After stirring for a minute, the copolymer was precipitated by steam stripping, and after drying, its Mooney viscosity and residual vanadium and chlorine were measured using fluorescent X-rays. The amount of remaining aluminum is 7g of polymer.
It was incinerated in a platinum crucible with 0.2 g of Na ₂ CO ₃ , dissolved in water and diluted hydrochloric acid, diluted to a predetermined amount in a volumetric flask, and then measured by atomic absorption spectrometry. The results are summarized in Table 1. Reference character examples 2 to 13 Similar to Reference Example 1, polyoxyethylene sorbitate tetraoleate (Rheodol manufactured by Kao Atlas Co., Ltd.) was used instead of polyoxyethylene monostearate.
430 (n≒5), 440 (n≒7), 460 (n≒10)) polyoxyethylene sorbitan tristearate (Kao Atlas Tween 65, n≒7), polyoxyethylene distearate (NOF manufactured by Nonion DS-60HN, n≒190), ε-caprolactone,
γ-butyrolactone, δ-valerolactone, γ-
The tests were conducted on nonalactone, pentanyrythritol tetraacetate, bentaerythritol tetraester (Unistar H4812R, manufactured by NOF Corporation), and pentaerythritol tetrastearate (Unistar H476, manufactured by NOF Corporation). The results are shown in the table. Example 1 Polyoxyethylene sorbitate tetraoleate (Rheodol 440 manufactured by Kao Atlas Co., Ltd.) was added to the ethylene copolymer solution 1 obtained by the method described in Reference Example 1.
Add 0.5g of and stir for 10 minutes, then add 200ml of water and stir for 20 minutes to emulsify the copolymer solution. then water
800 ml was added, stirred for 10 minutes, and then allowed to stand to separate water and the ethylene copolymer solution. The ethylene copolymer solution was steam-stripped to precipitate the copolymer. After drying, the Mooney viscosity and the amounts of residual vanadium, chlorine, and aluminum were measured in the same manner as in Reference Example 1. The results are shown in Table 1. Example 2 ε-caprolactone was used in place of the tetraolefinic acid polyoxyethylene sorbitol in Example 1.
After adding 0.5 g and stirring for 10 minutes, 200 ml of water in which 0.08% by weight of polypropylene glycol (molecular weight 400) was dissolved was added and stirred for 20 minutes to emulsify the copolymer solution. Thereafter, 800 ml of water was added and treated in the same manner as in Example 1. The results are shown in the table. Example 3 Polyethylene glycol nonyl phenyl ether (Daiichi Kogyo Seiyaku Co., Ltd. Neugen EA-80) was used instead of the polypropylene glycol in Example 2.
Emulsify using 200ml of water containing 0.04% by weight,
It was treated in the same manner as in Example 2. The results are shown in the table. Comparative Example 1 Water was used instead of polyoxynytylene monostearate in Reference Example 1 to terminate polymerization. It was treated in the same manner as in Reference Example 1, and the Mooney viscosity, residual vanadium amount, residual chlorine amount, and residual aluminum amount were measured. It can be seen that the Mooney viscosity is increased and the amount of residual catalyst is large compared to the example. Comparative Examples 2 to 7 Instead of polyoxyethylene monostearate in Reference Example 1, glycerol tristearate, ethylene glycol diacetate, pentaerythritol diester (Unistar, manufactured by NOF Co., Ltd.)
H476D), pentaerythritol triester (Unistar H470T, NOF Corporation), epoxylated soybean oil, and propylene glycol (molecular weight 400). Although an increase in Mooney viscosity can be prevented, the amount of catalyst residue is significantly higher than in Examples. Comparative Example 8 The same procedure as in Example 3 was carried out using glycerol tristearate instead of ε-caprolactone. The results are shown in the table. Despite the combined use of the phase inversion method, the amount of catalyst residue was significantly higher than in the examples. Reference Example 14 N-hexane 3/hr vanadium oxytrichloride 1.16mM/hr, ethylene aluminum sesquichloride 17.4mM/hr, dicyclopentadiene 58g/hr, ethylene 290g/hr, propylene 880g/hr Hydrogen is continuously fed so that the hydrogen content in the gas phase of the polymerization reactor is maintained at 25%.
The reaction was carried out at 27°C and at 8 kgG/cm ² so that the liquid residence time was 40 minutes. The concentration of ethylene copolymer in the effluent was 95g/. For this copolymer 1, pentaerythritol tetraester (NOF Unistar Co., Ltd.)
0.5g of H4812R) was added and treated in the same manner as in Example 1 to obtain a copolymer with little catalyst residue. The results are shown in Table 2. Reference Example 15 Polymerization was carried out under the same conditions as in Reference Example 14, and copolymer 1 was treated with polyoxyethylene sorbitate tetraolefinate (Rheodol manufactured by Kao Atlas Co., Ltd.).
440) was added and treated in the same manner as Reference Example 14,
A copolymer with less catalyst residue was obtained. The results are shown in Table 2. Comparative Example 9 Pentaerythritol diester (NOF Unistar H476D) was used instead of pentaerythritol tetraester in Reference Example 14. The results are shown in Table 2. Comparative Example 10 In place of the pentaerythritol tetraester in Reference Example 14, 200 ml of water was added. The results are shown in Table 2. Table 2 shows that polymers with a large amount of catalyst residue have poor thermal stability and corrode iron.

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Claims (1)

[Scope of Claims] 1. A method for producing synthetic rubber in which synthetic rubber is produced using a polymerization catalyst containing a transition metal compound and an organoaluminum compound as main components, the solvent is removed by steam stripping, and the polymer is recovered,
After stopping the polymerization using at least one compound selected from alkyl ester derivatives of polyethylene glycol, cyclic ester compounds, and pentaerythritol tetraester as a polymerization terminator, 0.05 to 1 part of the polymer solution is used. Add 4 parts of water to emulsify the polymer solution, then further add 0.2 to 2.0 parts of water to 1 part of the polymer solution to invert the phase, and desolvent the separated polymer solution by steam stripping. A method for producing synthetic rubber characterized by: 2. The method according to claim 1, wherein the transition metal compound is a soluble vanadium compound. 3. The method according to claims 1 and 2, wherein the synthetic rubber is an ethylene-propylene synthetic rubber.