JPH0316365B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention combines ethylene, α-olefin and 5-ethylidene-2-norbornene (hereinafter abbreviated as ENB) or dicyclopentadiene (hereinafter referred to as DCP).
Regarding an improved method for producing a ternary rubber-like copolymer consisting of a non-conjugated diene such as The present invention relates to a method for recovering a copolymer using a steam stripping method. Conventionally, the industrial method for producing a ternary rubbery copolymer consisting of ethylene, α-olefin, and ENB or DCP uses n-hexane, n-hexane, and n-hexane as solvents.
- A solution polymerization method in which the copolymer is polymerized by dissolving it in a solvent using normally liquid inert hydrocarbons such as heptane or cyclohexane, and a solution polymerization method in which the copolymer is polymerized by keeping the monomer in a liquid state. There is a suspension polymerization method in which polymerization is carried out in a state in which a rubbery copolymer is precipitated and dispersed in the liquid monomer. However, in solution polymerization, in order to industrially continuously and stably obtain the rubbery copolymer, it is necessary to make the solution in the polymerization vessel completely homogeneous and to efficiently remove the heat of the polymerization reaction. The combined solution must be easy to stir and transport. Therefore, it is necessary to control the viscosity of the copolymer solution to some extent by adjusting the concentration of the copolymer in the copolymer solution, and industrially, the maximum value of the copolymer concentration is
Currently, it is limited to 10-18% by weight. Therefore, the amount of solvent contained in the copolymer solution is approximately 80
Separating this solvent reaches ~90% by weight,
A large amount of energy must be spent for purification and recovery, and if the amount of solvent is reduced, the viscosity of the solution will inevitably increase. As mentioned above, this will cause problems in operation. On the other hand, it can be said that the solvent-free suspension polymerization method does not have such technical problems. This method is industrially advantageous because it can be handled in the same low-viscosity solution state as the copolymer, and it does not require much energy to recover the copolymer. As described above, the solvent-free suspension polymerization method is an advantageous method from an economic point of view, but since the entire polymerization solution system is occupied by the monomer, there is virtually no solvent. The concentration of α-olefin becomes higher than that of non-conjugated dienes such as ENB and DCP, and therefore the relative concentration of non-conjugated diene decreases, which reduces the reaction rate of non-conjugated diene and unreacted As the amount of non-conjugated dienes increases, not only does it take a lot of energy to remove these non-conjugated dienes with high boiling points, but if a large amount of these dienes remain in the product rubber, quality, especially the physical properties of the vulcanizate, are affected, and it is difficult to remove them during the finishing process. This has led to major problems such as foul odors that contaminate the working environment and corrode equipment, and a method to eliminate them as completely as possible has been desired. In order to solve this problem, the inventors conducted extensive research on a method for efficiently removing these non-conjugated dienes such as ENB and DCP that remain unreacted, and as a result, the present invention was achieved. That is, in the present invention, when ethylene, α-olefin, and non-conjugated diene are copolymerized and recovered by a suspension polymerization method, a titanium chloride compound is selected as a reduction metal compound which is one component of the polymerization catalyst, and an organic When used in combination with an aluminum compound and by adding 5 to 40 parts by volume of a hydrocarbon having 5 to 8 carbon atoms per 100 parts by volume of liquid α-olefin, the copolymer is extremely effective in removing the catalyst. By collecting it using the so-called steam stripping method,
It has been discovered that the amount of non-conjugated diene remaining in a rubbery copolymer can be removed with surprising efficiency, and an improved method for producing a rubbery copolymer is provided. From the results of the research conducted by the inventors, it has been found that the specificity of the catalyst and the addition of hydrocarbons in the method of the present invention have the following effects. First, regarding the catalyst, as a reduction metal compound,
Conventionally widely used VOCl ₃ , VCl ₄ , VO
In the case of the combination of vanadium compounds in solution, such as (AcAc) ₃ , and organoaluminum compounds, it is extremely disadvantageous that during suspension polymerization the catalyst becomes inhomogeneous in the reactor, and also precipitates in flocculent forms, resulting in This results in a large amount of abnormally large particles being contained in the copolymer particles that are precipitated, which not only makes transportation difficult; It is extremely difficult to remove high boiling point non-conjugated dienes such as ENB and DCP from copolymer particles using the steam stripping method. On the other hand, when a solid trivalent or tetravalent titanium chloride compound is used in combination with an organoaluminum compound, the copolymer is produced in the form of uniform fine particles because the catalyst is in the form of a uniform fine powder in the polymerization vessel. Therefore, the diffusion rate of unreacted non-conjugated dienes such as ENB and DCP in the particles increases, making them easier to remove. Furthermore, problems such as blockage during transportation are virtually eliminated. Next, regarding the addition of hydrocarbons, for example, if copolymerization is carried out in liquid propylene substantially without a solvent, a rubber-like copolymer can be obtained in the form of a stable fine particle slurry with precipitated particles as described above, but on the other hand, Since the particles themselves remain extremely dense and tight, it is not preferable to diffuse and remove unreacted unconjugated dienes with high boiling points from the particles. Therefore, by including an appropriate amount of a hydrocarbon having 5 to 8 carbon atoms in the slurry system, it is possible to stably maintain the shape of the particles and swell the particles appropriately without dissolving them. Removing unreacted nonconjugated diene from swollen polymer particles has much less diffusion and resistance than removing it from tight particles.
It's easy. As mentioned above, when conventional vanadium compounds and organoaluminum compounds are used as catalysts,
Huge particles of rubbery copolymer are formed, making it difficult to remove unreacted non-conjugated diene, but in this case
Even if hydrocarbons of 1 to 8 are added, the adhesion between particles increases, and the number of giant particles increases, making it impossible to obtain the effects of the present invention. This is thought to be due to the difference in the shape of the catalyst. That is, the method of the present invention can only be made effective by selecting a catalyst and using a specified hydrocarbon. The hydrocarbon having 5 to 8 carbon atoms in the present invention is preferably selected from hydrocarbons that do not inhibit polymerization activity, such as n-pentane, i-pentane, n-hexane, cyclohexane, n-heptane, and n-octane. In particular, n-hexane has swelling properties,
Preferable in terms of boiling point. Hydrocarbons having 4 or less carbon atoms are not preferred because they have poor dissolving power for rubbery polymers and cannot swell the copolymer particles. Furthermore, hydrocarbons having 9 or more carbon atoms have a high swelling ability, but have a high boiling point and require a lot of energy to separate from the copolymer, which is economically disadvantageous and undesirable. The amount of the hydrocarbon added is α-olefin 100
5 to 40 parts by volume. (here,
The capacity part shows the value of 10Kg/cm ² abs at 15℃. ) If the amount of hydrocarbon is less than 5 volumes per 100 parts by volume of liquid α-olefin, the rubbery copolymer particles in the suspension will not be sufficiently swollen by the hydrocarbons, and therefore at the time of steam stripping. In this case, a large amount of unreacted non-conjugated diene remains in the rubbery copolymer particles, making it impossible to achieve the object of the present invention. Also, the amount of hydrocarbon added is
If the amount exceeds 40 parts by volume compared to 100 parts by volume, the rubber-like copolymer particles will swell significantly, cannot exist in particulate form, and a considerable portion will dissolve, the viscosity of the polymerization system will increase significantly, and it will no longer be suspended. This is not preferable since it is no longer in the form of polymerization, but rather resembles solution polymerization. When to add hydrocarbons having 5 to 8 carbon atoms: (a) Add them in advance before supplying the catalyst to the polymerization reactor, and then continuously add the hydrocarbons at the same time as the catalyst is continuously supplied. . (b) Hydrocarbons are continuously added at the same time as the catalyst is supplied to the polymerization reactor. (c) After the polymerization reaction is completed, hydrocarbons are continuously added. Among them, method (a) is preferred because it can swell the polymer particles well. The above-mentioned addition method can also be applied to batch polymerization. The organoaluminum compound in the present invention is a compound represented by the general formula AlR _o X _3-o (where R is 1
a hydrocarbon group with a carbon number of ~5, X is a halogen, and n is 3, 2, 1.5 or 1)
and preferably a compound selected from triethylaluminum, triisobutylaluminum, diethylaluminum chloride, diisobutylaluminum chloride, ethylaluminum sesquichloride, isobutylaluminum sesquichloride, or a mixture thereof. The titanium chloride compound, which is a catalyst component used in the present invention, is trivalent or tetravalent titanium chloride.
−65489, 57−65490, 57−65491, 57−65492, 57
-92121, 57-99955 and JP-A-57-55905
Copolymers prepared by the method described in Japanese Patent Publication No. 57-9566, etc. can be used, but the resulting copolymer has less crystallinity and is more rubber-like.
Patent application Sho 57-65489, 57-65491, 57-65492, 57-
92131 are preferred. The ratio of the titanium chloride compound (A) and the organoaluminum compound (B) constituting the catalyst can be in the range of 2/1 to 100/1 expressed as a molar ratio of (B)/(A), but if the polymer is In order to make it amorphous and easily swell, and to effectively achieve the purpose of the present invention, the ratio is 5/1 to 20/1.
is preferred. The α-olefin in the present invention has 3 to 10 carbon atoms.
an α-olefin having, for example, propylene,
1-butene, 1-pentene, 1-hexene, 4-
Examples include methyl-1-pentene, 1-octene, 1-decene, etc., particularly preferably propylene, 1-decene, etc.
It is butene. Non-conjugated dienes that can be used in the present invention include linear or cyclic dienes or polyenes, such as 5-methylene-2-norporene, 5-ethylidene-2-norbornene (ENB), 5-propylidene-2-norbornene, and diene. Cyclopentadiene (DCP), 5-isopropenyl-2-norbornene, etc., have high copolymerization reactivity and are copolymerizable with ENB, which has many advantages in terms of physical properties of vulcanized rubber, such as fast vulcanization speed. is relatively high;
DCP, which is available at low cost, is particularly preferably used. In the present invention, the polymerization temperature is preferably 0 to 80°C, but is not particularly limited. The steam stripping method in the present invention is
Any method generally used in industry may be used. For example, the temperature for steam stripping is 70~
120℃ is preferable, and the operating pressure is atmospheric pressure to 15℃.
Kg/cm ² G is preferred. The average residence time of the rubbery copolymer in the stripper is about 1 hour. EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited by these Examples unless the gist thereof is exceeded. In each Example and Comparative Example, the content (ppm) of unreacted non-conjugated diene compounds remaining in the rubbery copolymer was calculated by adding 2g of the rubbery copolymer recovered by steam stripping to n-hexane. 100ml
Gas chromatography (using Shimadzu GC-6A, column silicon KF-96.3%5)
m) using the calibration curve method. Further, the iodine value, which indicates the amount of non-conjugated diene bonds in the rubbery copolymer, was determined by the iodine titration method. Example 1 (1) Preparation of titanium compound catalyst 3 g of anhydrous magnesium chloride and 40 g of di(2-ethylhexyl) 2-ethylhexylphosphonate were placed in a flask that had been thoroughly dried and purged with nitrogen.
was added and heated to 100°C to completely dissolve the magnesium chloride, then cooled to room temperature and 150 ml of dry n-hexane was added. Next, add 100 ml of dried n-hexane to a separately prepared flask.
and 7.5 g of titanium tetrachloride were added, followed by 10 g of dioctylphosphaate, and the entire amount was added to the magnesium chloride solution. Next, 60 g of titanium tetrachloride was slowly added to the above mixture while stirring, and a fine particulate solid was precipitated, washed five times with 250 ml of dry n-hexane, and used as a catalyst. The amount of titanium tetrachloride in the prepared catalyst was determined by atomic absorption spectrometry. (2) Polymerization and recovery of copolymer Polymerization and recovery of the rubbery copolymer were performed as follows. 8 kg of liquid propylene, 0.6 kg of n-hexane, and 0.14 kg of 5-ethylidene-2-norbornene (ENB) were charged into a 16 stainless steel polymerization vessel equipped with a stirring blade that had been thoroughly dried and replaced with propylene gas. After the temperature inside the polymerization vessel was set to 55°C, ethylene gas was blown into the vessel to make the pressure inside the polymerization vessel 30Kg/cm ² G. Next, 2.5g/triisobutyl aluminum
H and the titanium chloride catalyst supported on magnesium chloride prepared by the above preparation method in terms of titanium tetrachloride.
Continuously add 0.06g/H, simultaneously propylene 8/H, ethylene 0.9Kg/H, ENB0.14
Kg/H and n-hexane 0.6/H were added continuously. The reaction mixture was continuously extracted so that the liquid level in the polymerization vessel was always constant. The copolymer particles in the polymerization vessel had a particle size of 2 to 4 mm, were uniformly dispersed in the suspension, and were clearly in a swollen state. The reaction mixture in the polymerization vessel 4 hours after the start of polymerization was introduced into a 100-volume distillation vessel equipped with a stirrer.
Steam stripping was performed in hot water at 100°C under atmospheric pressure for 1 hour to recover the rubbery copolymer. Table 1 shows the analysis results of the rubbery copolymer and the measurement results of the content of non-conjugated diene compounds remaining in the rubbery copolymer after steam distillation. Example 2 In Example 1, the amount of n-hexane initially charged was 1.2, and the amount of n-hexane continuously added during polymerization was 1.2/H, so that n-hexane/
The polymerization should be carried out at a constant volume ratio of liquid propylene of 15 parts/100 parts, and the pressure during polymerization should be 29
The method of Example 1 was repeated except that Kg/cm ² G was used. The results are shown in Table-1. Example 3 In Example 1, the amount of n-hexane charged at the beginning was set to 2.8, and the amount of n-hexane added continuously during polymerization was set to 2.8/H.
Polymerization must be carried out at a constant volume ratio of liquid propylene of 35 parts/100 parts, and the pressure during polymerization must be 28 parts.
The method of Example 1 was repeated except that Kg/cm ² was used. The results are shown in Table-1. Comparative Example 1 In Example 1, the amount of n-hexane initially charged was 0.16, and the amount of n-hexane continuously added during polymerization was 0.16/H, so that the volume ratio of n-hexane/liquid propylene was always 2. Polymerization should be carried out at a constant ratio of parts/100 parts, and the pressure during polymerization should be
The method of Example 1 was repeated except at 31 Kg/cm ² G. The results are shown in Table-1. The rubbery copolymer particles in the suspension during polymerization had a particle size of 0.5 to 2 mm, showed almost no swelling, and maintained a very tight shape.
Furthermore, it was observed that the rubbery copolymer particles recovered by steam stripping were also less foamed than in Examples 1 to 3. Comparative Example 2 In Example 1, the amount of n-hexane initially charged was 3.4, and the amount of n-hexane continuously added during polymerization was 3.4/H, so that the volume ratio of n-hexane/liquid propylene was always 43 parts/H. Polymerization was carried out at a constant rate of 100 parts, and the pressure during polymerization was 27 kg/
The method of Example 1 was repeated except that cm ² G was used.
The results are shown in Table-1. In this case, the rubbery copolymer during polymerization hardly became particulate in liquid propylene, and it was observed that the rubbery copolymer was clearly dissolved. Example 4 In Example 1, as the non-conjugated diene,
DCP was used instead of ENB, and all other conditions were repeated under the same conditions. That is, liquid propylene 8,n-
Hexane 1.6, dicyclopentadiene (DCP)
After 0.38 kg was charged and the temperature inside the polymerization vessel was brought to 55°C, ethylene gas was blown into the reactor to make the pressure 29 kg/cm ² G. Next, the same catalyst as in Example 1 was continuously added at the same flow rate to start polymerization, and at the same time liquid propylene 8/
Polymerization was carried out by continuously adding H, 0.9 kg/H of ethylene gas, and 0.16 kg/H of DCP. Recovery of the rubbery polymer was carried out in the same manner as described in Example 1. The results are shown in Table-1. Comparative Example 3 In Example 4, the amount of n-hexane initially charged was 0.16, and the amount of n-hexane continuously added during polymerization was 0.16/H, so that n-hexane/
Polymerization must be carried out at a constant volume ratio of liquid propylene of 2 parts/100 parts, and the pressure during polymerization must be kept at 31
The method of Example 4 was repeated except that Kg/cm ² G was used. The results are shown in Table-1. In this case, the appearance of the suspension during polymerization was exactly the same as in Comparative Example 1. Comparative Example 4 In Example 2, except that 5.4 g/H of diethylaluminum monochloride and alcohol-denatured vanadium oxytrichloride were continuously added to the catalyst at a rate of 0.7 g/H in terms of vanadium oxytrichloride.
The method of Example 2 was repeated to obtain a rubbery copolymer. An alcohol-modified catalyst for vanadium oxytrichloride was prepared as follows. Pour 100 ml of dry n-hexane into a flask that has been sufficiently dried and purged with nitrogen, add 100 g of vanadium oxytrichloride, and then add n-butanol.
It was prepared by slowly adding 6.4 g while stirring. In this case, the particle size of the rubbery copolymer particles in the suspension is huge, reaching 10 to 30 mm.
This was extremely inconvenient for stirring and transport. Furthermore, a large amount of unreacted non-conjugated diene remained in the copolymer particles after steam distillation. The results are shown in Table-1.

【table】

[Table] 〓
〓DCP; dicyclopentadiene

Claims (1)

[Scope of Claims] 1. In a method for copolymerizing ethylene, α-olefin and non-conjugated diene by a suspension polymerization method and recovering the copolymer, the presence of a catalyst comprising a titanium chloride compound and an organoaluminum compound Below, before the recovery step, 5 to 40 parts by volume of an aliphatic hydrocarbon having 5 to 8 carbon atoms is added to 100 parts by volume of α-olefin, and the copolymer is recovered by a steam stripping method. A method for producing a characteristic rubber-like copolymer.