JPS6040104A - Purification of rubber-like polymer - Google Patents

Abstract

PURPOSE:To purify a rubber-like polymer efficiently, by adding a surface active agent and water to a slurry solution having finished a polymerization reaction into an emulsified state previously, adding a good solvent for the polymer to form an oil-in-water type emulsified state, removing the catalyst residue. CONSTITUTION:In removing the catalyst residue from a rubber-like polymer obtained by using a catalyst consisting of a transition metal compound and an organoaluminum compound in a poor solvent by slurry polymerization method, at the first stage, the polymer slurry solution is blended with a surface active agent [e.g., polyoxyethylene alkyl(phenyl) ether type nonionic surface active agent, (polyoxyethylene) sorbitan ester type nonionic surface active agent] so that an emulsion is previously formed. At the second stage, a good solvent (e.g., cyclohexane, toluene, etc.) for the polymer is added to the emulsion to give an oil-in-water type emulsion, and the catalyst residue is extracted into a water phase.

Description

Detailed Description of the Invention The present invention uses a catalyst comprising a transition metal compound and an organoaluminum compound to efficiently remove catalyst residues contained in a rubbery polymer obtained by slurry polymerization in a poor solvent. This invention relates to an improved method for purifying comb-like polymers.

Industrial polymerization methods for rubbery polymers include n-.

There are solution polymerization methods, in which the copolymer is polymerized by dissolving it in normally liquid inert hydrocarbons such as n-tane, n-hexane, n-hebutane, cyclohexane, and toluene, and polymerization methods in which the copolymer is polymerized in a solvent that does not dissolve the polymer. There is a slurry polymerization method in which polymerization is carried out in a state in which the polymer is precipitated and dispersed, but the latter has many advantages as described below.

(2) Even when the polymer concentration is high, it can be handled with substantially the same low viscosity as the reaction medium, making mass transfer and mixing easy.

(2) Reactor volume per unit amount of polymer produced is small.

■ Since a liquid monomer can be used as a solvent, there is no need for a solvent recovery process, which is required in solution polymerization, and energy consumption can be significantly reduced.

Among them, regarding (2), when producing rubber-like polymers by solution polymerization, it is usually necessary to use 10 to 20 times more solvent per unit weight of the polymer, and the energy required to recover this solvent is extremely large. Slurry polymerization, which uses monomers as a solvent, can reduce this energy, and this advantage is extremely large industrially.Although the slurry polymerization method has many advantages as described above, it also has the disadvantages of the reverse method. have.

That is, (1) since the catalyst is included in the produced polymer particles, it is extremely difficult to remove the residue, and if a large amount remains in the polymer, it will only cause coloring of the polymer. It is known that aging of polymers is accelerated.

(2) The presence of residual liquid may cause corrosion of metal materials such as equipment and instruments used in contact with the rubbery polymer during manufacturing and processing steps.

As mentioned above, while the slurry polymerization method has many advantages,
Due to the serious drawbacks mentioned above, the current situation is that it is not possible to take full advantage of its advantages. Therefore, it has been desired to remove catalyst residues as much as possible by slurry polymerization.

In view of this situation, the present inventors developed a method for removing catalyst residues from rubbery polymers obtained by slurry polymerization.
As a result of intensive research, an extremely efficient method was discovered and the present invention was completed.

That is, in the present invention, a surfactant is added to the polymer slurry liquid when removing catalyst residues contained in a rubbery polymer obtained by slurry polymerization using a catalyst consisting of a transition metal compound and an organoaluminum compound. and water are added and mixed to preform an emulsion in which polymer particles surrounded by a slurry solvent are dispersed in water, and then a much smaller amount of polymer than that used in solution polymerization is added to the emulsion. A good solvent (hereinafter sometimes simply referred to as a solvent) that can dissolve the polymer is added, and the droplets of the polymer dissolved in the mixture of the slurry solvent and the solvent form an oil-in-ice emulsion in which the polymer droplets are finely dispersed in water. The present invention provides an efficient method for purifying rubber-like polymers, which is characterized in that catalyst residues are extracted and removed from the droplets in water.

The present invention will be explained in detail below.

Known transition metal compounds used as polymerization catalysts for rubbery polymers include, for example, nickel, cobalt, vanadium, niobium, tungsten, titanium, rhodium, molybdenum, and zirconium.

Known organoaluminum compounds include, for example, trialkylaluminum, dialkylaluminum monochloride, alkylaluminum sesquichloride, alkylaluminum dichloride, and the like.

Examples of rubbery polymers include polybutadiene, polyisoprene, ethylene-α-olefin copolymers (ethylene-
These include α-olefin copolymers and ethylene-α-olefin-nonconjugated diene copolymers (hereinafter abbreviated as EPDM).

Among these, 1iJ'DM is strongly required to sufficiently remove catalyst residues in order to ensure good weather resistance and heat resistance, which are its physical characteristics.

In the case of KPDM, the transition metal compounds include vanadium oxytrichloride, vanadium tetrachloride, and their alcohols (
It is common to use vanadium compounds such as vanadium triacetylacetonate, oxyvanadium diacetylacetonate, etc., or vanadium compounds such as vanadium triacetylacetonate and oxyvanadium diacetylacetonate. The purification method of the present invention is a particularly effective means since the color polymer becomes colored and loses its commercial value.

In addition to vanadium compounds, titanium compounds such as titanium tetrachloride and titanium trichloride can also be used.

On the other hand, as the organic aluminum compound, for example, diethylaluminum monochloride, ethylaluminum sesquichloride, ethylaluminum dichloride, triethylaluminum, triisobutylaluminum, and mixtures thereof can be used.

As the α-olefin, propylene and 1-butene are preferable, but 1-hexane, 4-methyl-1, -o
Butene, 1-octene, etc. may also be used.

The non-conjugated diene which is the third component of EPDM is a linear or cyclic diene or polyene, for example, 5-
Methylene-2-norbornene, 5-nitylidene-2-norbornene (ENB), 5-propyritene-2-norbornene, dicycloR-ntadiene (DCP), 1.4-
Among them, hexadiene, 5-inpropanyl-2-norbornene, and the like are preferred, and among them, END and DCP are preferable.

However, E is a poor solvent for EPDM slurry polymerization.
Propylene, 1-butene, and halogenated hydrocarbons such as methylene dichloride, mesolodipromide, and ethylchloride, which do not substantially dissolve PDM,
Although there are mixtures of a solvent that does not dissolve PDM and a small amount of solvent, it is preferable to use propylene and 1-butene, which are volatile reaction monomers, as described above.

Next, a method for removing catalyst residue according to the present invention will be explained.

After carrying out a copolymerization reaction using the catalyst, monomer, and solvent described above, in the first step, water is added and mixed to the polymerization slurry in the presence of a surfactant to form an emulsion. However, as the surfactant used in this case, for example, nonionic surfactants of the polyoxyethylene alkyl ether type, polyoxyethylene alkyl phenyl ether type, sorbitan ester type, and polyoxyethylene sorbitan ester type are preferable. , cationic, anionic and amphoteric surfactants may be used in combination.

The surfactant may be made into an aqueous solution in advance and added to the slurry liquid of the rubbery polymer discharged from the polymerization reactor, or it may be added separately from water, but in either method, it is difficult to emulsify. Vigorous mixing of the surfactant, water, and polymeric slurry liquid is required to form a liquid. The amount of surfactant used may generally be about 0.01 to 0.3 percent by weight based on water.

On the other hand, the amount of water to be added may be such that when the solvent is added in the second step, water becomes a continuous phase and an oil-in-water type emulsion is formed. Quantitatively, it is preferable to add 0.4 to 2.0 parts by weight based on a total of 10 parts by volume of the poor solvent used in slurry polymerization and the bath agent added in the second stage.

Next, in the second step, a solvent is added to the emulsion to form an oil-in-ice emulsion, but in order to dissolve the rubbery polymer, the added solvent is substantially dissolved in water. It is necessary that it does not dissolve, and n-hexane, n-octane, n-/nan, cyclohexane, toluene,
Solvents such as methylcyclo-R, benzene, xylene, and ethylbenzene can be used.

The amount of these solvents added must be such that the rubber-like polymer can be dissolved in a state where the solvent is mixed with the slurry solvent contained in the oil droplets of the oil-in-water emulsion.

That is, when the rubbery polymer is EPDM, in order to make it into Bath M, it is recommended that the solubility parameter (hereinafter abbreviated as S-P value) of the slurry solvent and the solvent mixture be 6.8 or more. preferable. When the slurry solvent is propylene and cyclohexane is used as the additive solvent, the s-
A p-value of 6.8 (I) is favorable for dissolving BPDM.

In addition, preferable sp for dissolving the rubbery polymer
The value will be different depending on the type of rubbery polymer.

Note that the s-p value referred to in the present invention is the value at 25°C,
The sp values of typical solvents (agents) are as follows.

Propylene...(S,i,)7-n...67, n-hexane...72, n-octane...7.5, n-nonane...Z6, cyclohexane...8.2, Toluene 89, benzene 9.2, ethylben 7,
.

8 Also, the S-P value of a liquid mixture is generally expressed in Table 1 by the arithmetic expression of the S-P value according to the volume fraction of each component.

The type of solvent is preferably one that can dissolve the rubbery polymer in a small amount and has a relatively low boiling point, considering recovery in a later process.Among the good solvents mentioned above, cyclohexane and toluene are preferred. can be suitably used.

Next, the temperature at which an oil-in-ice droplet type emulsion is formed and the catalyst residue is removed is preferably 10 to 70°C; below this range, the viscosity of the droplets increases significantly, and above this range, the surface activity increases. As explained above, the oil-in-water type emulsification state, which is undesirable because the effect of the agent deteriorates slowly, can be changed to a better state by stirring for about 10 minutes and then stirring vigorously for 20 to 120 minutes. To summarize the characteristics of the rubbery polymer purification method according to the present invention: (1) The slurry liquid after the polymerization reaction is kept in an emulsified state in advance.

(2) Next, a small amount of solvent is added to the emulsion containing the slurry solvent to form an oil-in-ice emulsion, and the catalyst is removed.

According to the method of the present invention, the following effects can be obtained.

(2) By keeping the slurry liquid in an emulsified state in advance, oil droplets can be finely dispersed in water in the oil-in-water type emulsified state formed in the next step.

In other words, the polymer particles discharged from the polymerization reactor are extremely small, so by emulsifying them in advance, they can maintain this small state. When a solvent is added, the shape changes to minute oil droplets, and as a result, the substance Transfer is promoted and the catalyst can be easily extracted into the aqueous phase. On the other hand, if a method is used in which a solvent is added prior to emulsification, an oil-in-water emulsion is likely to be formed after a high viscosity state. Therefore, the oil droplets are not dispersed minutely and sufficient catalyst extraction is hindered, which is undesirable.

Note that when the slurry liquid is emulsified, the state is such that fine particles of the polymer surrounded by the slurry solvent are dispersed in water.

■ Since the polymerization reaction is in a slurry state and the catalyst removal is in an oil-in-water type emulsified state, operations such as stirring and transfer can be performed while maintaining a low viscosity state from polymerization to catalyst removal. .

On the other hand, if a solvent is added prior to emulsification, stirring and mixing operations are required in a highly viscous state, which is undesirable in terms of energy consumption.

■ Since a good solvent is added to a situation where a slurry solvent, which is a poor solvent that does not dissolve the polymer, is present, a solvent that is relatively similar to a poor solvent that can dissolve the polymer is generated, which reduces the amount of polymer that is formed. The viscosity of the oil droplets of the combined M liquid decreases and the movement of the material a is promoted.

(2) When a solvent is added to an emulsified slurry, the solvent is rapidly incorporated into the slurry solvent, allowing the polymer to be dissolved and oil droplets to be formed in a short period of time.

Another method to make oil droplets is to emulsify the solvent with water and add it to the slurry liquid, but this method requires a long time to dissolve the polymer, as shown in the examples below. Undesirable.

(2) Forming a mixed solvent that dissolves a polymer with a slurry solvent and a solvent means, in other words, that the slurry solvent can be used as a solvent, and therefore the amount of newly added solvent can be reduced. Specifically, the amount of EPDM per unit weight of the polymer is determined by slurry polymerizing EPDM using propylene as a solvent and using cyclohexane as a solvent for dissolving the polymer, and when producing EPDM by solution polymerization. When comparing the amount of solvent used, the latter has a weight ratio of 10 to 20, while the former has a weight ratio of 1.5
-6 weight ratio, which is extremely low, which makes the catalyst removal method of the present invention advantageous.

The present inventors have also discovered that an even higher catalyst removal effect can be obtained by adding a polymerization terminator to the polymerization slurry before adding water to form an emulsion, and this method also Moreover, it is included in the scope of the present invention. In this case, the polymerization terminator that can be suitably used is one having a structure having an alkyl group of 01 to C20, where 1 is an integer of 3 to 200), such as polyoxyethylene monoalkylate, polyoxyethylene tetraoleate, etc. Examples include sorbitol, polyoxyethylene sorbitan trialkylate, polyoxyethylene moalkylate, and among these, polyoxyethylene sorbitate tetraoleate is particularly preferred.

The amount of these compounds added is 0.5 to 10 times, preferably 1 to 5 times the weight of the transition metal compound as a polymerization catalyst. By removing a portion of the solvent, the amount of solvent added can be substantially reduced, but this method is also within the scope of the present invention. Further, in order to shorten the extraction time of the catalyst residue and the dissolution time of the polymer, an emulsifying machine or frame breaking machine which applies high shear force can be appropriately arranged and used.

Next, the present invention will be specifically explained with examples.
The present invention is not limited to the examples in any way.

In the examples, the amount of catalyst residue was measured by atomic absorption spectrometry.

Example 1 1.5 times the mole of dehydrated and dried n-butyl alcohol was gradually added to vanadium oxytrichloride at room temperature, and the modified vanadium compound was mixed with ethylene in liquid propylene in the presence of diethylaluminium chloride. To a propylene slurry of EPDItll obtained by copolymerizing propylene and ENB, OO808 weight of surfactant polyoxyethylene nonyl phenyl ether (trade name 1. Neugen EA-80) was added to 1 part of liquid propylene. Stir vigorously (approximately 1,
000 rpm) to form an emulsion and stirring was maintained for 10 minutes. This emulsion contained propylene and EPDM particles finely dispersed in water.
of cyclohexane (S-P value of mixed solvent 6.9) was added, and the mixture was stirred vigorously while maintaining the temperature at 30 to 55°C (
approximately 1,000 rpm).

After stirring for 60 minutes, it was confirmed that the EPDM was dissolved and finely dispersed as several drops in the water, and the stirring was stopped.

After stopping stirring, let this emulsion stand still for about 1 hour.
PI) It was divided into Mδ liquid and water containing a surfactant.

Table 1 shows the analysis results of KPDM obtained by removing the solvent from the EPDi4 solution separated from the ice overnight by well-known steam stripping and drying.

The polymerization temperature was 35°C, and the catalyst yield was 446g -B
PDlvl / g-At2,72 [1g-EPD
M/g -V and the EPDM concentration in the polymerization slurry was 31% by weight.

Example 2 The vanadium compound is vanadium oxytrichloride,
Liquid propylene 1 1 was added to a propylene slurry of 6 EPDM obtained by copolymerizing in liquid propylene in the same manner as in Example 1.
1.5 parts of a 0.10 weight percent aqueous solution of the same surfactant as in Example 1 was stirred vigorously (approximately 1,000 rpm).
pm) Gradually add to the mixture while stirring to form an emulsion.
It was maintained for 0 minutes.

Next, 0.4 parts of toluene (s-p value of the mixed solvent: 69) was added to the emulsion based on 1 part of liquid propylene, and the mixture was stirred for 60 minutes while maintaining the temperature at 30 to 35°C.
approximately 1.00 Orpm). .

The subsequent operations were carried out in the same manner as in Example 1, and the analysis results of the obtained polymer are shown in Table 1.

The polymerization temperature was 27°C and the catalyst yield was 571 g-FJ'
DM/g-AA, 3,220 g-KPDM/g-V
The EPDM concentration in the Xi polymerization slurry was 64% by weight.

Example 6 El)D obtained by copolymerization under the same setting conditions as Example 1
Half of the liquid propylene solvent was filtered from the propylene slurry of M to 0 to 35°C by jacket heating.8. [
(-Removed by evaporation while retaining.

Next, 0.08% of the same surfactant as in Example 1 was added to 1 part of liquid propylene of the EPDM slurry that remained unevaporated.
1.5 parts of the weight percent aqueous solution was added and stirred vigorously to form an emulsion, and stirring was continued for 10 minutes for 40 minutes. .

This emulsion was then added with 0.5 ml of
part of cyclohexane (S/P value of mixed solvent 6.8)
f: was added and vigorously stirred for 6Q minutes while keeping the temperature at 30-35°C.

The subsequent operations were the same as in Example 1.

Table 1 shows the phase separation results of the obtained polymer.

The polymerization temperature was 30°C and the catalyst yield was 481 g-KPD.
M/g, -kA, 2,9loQ g-EPDM/g-
The EPDIφ concentration in the liquid propylene before removing VX and half of the propylene L/7 was 64 weight percent. Sura IJ - Since the liquid propylene solvent was evaporated, the amount of cyclohexane added to achieve the S-P value that dissolves EPDM could also be reduced to a bar.
However, as shown in Table 1 (the catalyst residue in EPDM could be reduced to the same level as in Examples 1 and 2).

Example 4 EPDM obtained by copolymerization under the same setting conditions as Example 1
Polyoxyethylene sorbitol tetraoleate (trade name, Rheodol) was added as a polymerization terminator to the propylene slurry in an amount of 2.5 times the weight of the vananium compound used in the copolymerization, and the mixture was stirred for 5 minutes. Next, the slurry was emulsified, EPDM was dissolved, droplets were formed, the catalyst residue was extracted, the solvent was removed, and the polymer was dried in the same manner as in Example 1, and the polymer was analyzed.

The analysis results are shown in Table-1.

The polymerization temperature was 66°C and the catalyst yield was 398 g-BT.
DIA/ g-At, 2,515 g-EPDM/
g-V, and the EPDM concentration in the polymerization slurry was 29% by weight.

Comparative Example 1 E]'] obtained by copolymerization under the same setting conditions as Example 1
0.0% of the surfactant polyoxyethylene nonylphenyl ether was added to the propylene slurry of M) in the same manner as in Example 1.
0.08 weight percent aqueous solution was added to 1 part of liquid propylene to form an emulsion, and the mixture was stirred vigorously for 2 hours (approximately 1.00 Orpm) while maintaining the temperature at 60 to 35°C.
) did. Next, stirring was stopped, the entire amount of liquid zolopyrene was evaporated off, and the water was left to stand for 1 hour to separate the polymer and water.1.The EPDM thus separated from water was diluted by steam stripping. <A small amount of zoropyrene and the solvent for diluting the catalyst were removed and the mixture was dried.

Table 1 shows the analysis results of the EPDM.

The polymerization temperature was 36°C and the catalyst yield was 415 g-EPD.
M/z-A1. , 2,620 g-1i:PI)M
/g-V, and 1 in the polymerization solution was 60% by weight of DM concentration 1, ratio 111. Father Example 2 EPDM obtained by copolymerization under the same setting conditions as Example 1
To the propylene slurry was added 0.6 parts of cyclohexane per 1 part of liquid propylene, and the mixture was stirred for about 1 hour while maintaining the temperature at 30 to 35°C.

The state after about 1 hour was a highly viscous homogeneous solution in which EPDM was completely dissolved.

Next, a 0.08 weight percent aqueous solution of the same surfactant as in Example 1 was added in an amount of 1 part per 1 part of liquid propylene, and the mixture was vigorously stirred for 60 minutes (approximately 1.000 rpm) while maintaining the temperature at 30 to 65°C. ).

The subsequent operations were the same as in Example 1. The analysis results of the obtained polymer are shown in Table-1.

The polymerization temperature was 33°C and the catalyst yield was 498 g-El"
DIφ/g-AL%, 3.026 g-BPDM/
g-V, and the EPDM concentration in the polymerization slurry is 36
Weight percent.

Comparative Example 6 The amount of cyclohexane added was 0 per part of liquid propylene.
Polymerization and catalyst residue removal were carried out under the same conditions as in Example 1, except that the amount was reduced to 6 parts (SP value of the mixed core medium was 6.6).

When the emulsion was collected and observed 60 minutes after the addition of cyclohexane, it was found that the oil droplets were finely dispersed in the water, but the EPDM was not dissolved in each oil droplet and was in a swollen state.

The polymerization temperature was 63°C and the catalyst yield was 465g-EPD.
M/g-At, 2,910 g-EPDM/g-v
,,The IDPDM concentration in the polymerization liquid slurry was 52% by weight.

Comparative Example 4 Jc, p obtained by copolymerization under the same setting conditions as Example 1.
Add a pre-prepared emulsion of water and cyclohexane to the Dy+ propylene slurry and stir vigorously for 60 minutes while maintaining the temperature at 30 to 55°C (approx. 1.00 Orpm).
) was carried out, and the mixture was left in the apparatus for about 1 hour to separate the IDM solution and water.

The EPDM solution separated from the water in this manner was collected and observed. Although a portion of the EPDM had been dissolved, a large amount of undissolved 1 uPDM remained.

The above emulsion of water and cyclohexane is a 0.08 weight/ξ-cent aqueous solution of the surfactant used in Example 1, 7fi, 1
0.6 parts of cyclohexane per part of the sample was added and vigorously stirred. The amount of the emulsion of water and cyclohexane added was 16 parts per 1 part of liquid propylene.

The polymerization temperature was 35°C and the catalyst yield was 662 g-El)
DM/g, -AL, 2,320g-EPDM/g-V,
The concentration of 1iJ'DM in the polymerization slurry was 26% by weight.

Claims (3)

[Claims] (1) When removing catalyst residues contained in a rubbery polymer obtained by slurry polymerization in a poor solvent using a catalyst consisting of a transition metal compound and an organoaluminum compound, in the first step, the catalyst residue is added to the polymer slurry liquid. After mixing a surfactant and water to form an emulsion in advance, in the second step, a good solvent for the polymer is added to the emulsion to form an oil-in-ice emulsion to remove catalyst residue. A method for purifying a rubbery polymer, characterized by extraction into an aqueous phase. (2) The surfactant is a nonionic surfactant selected from polyoxyethylene alkyl ether type, polyoxyethylene alkyl phenyl ether type, sorbitan ester type and hydroxyethylene sorbitan ester type surfactants. A purification method according to claim (1), (3) The purification method according to claim (1), wherein the good solvent is cyclohexane and/or toluene.