JPH0153284B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to an improved method for producing polypropylene by gas phase polymerization. It is known to produce polypropylene in the presence of a catalyst system comprising a titanium trichloride composition and an organoaluminium compound. Inert hydrocarbon or
When produced by slurry polymerization in liquefied propylene, the amorphous low molecular weight polypropylene produced simultaneously with the polypropylene and the remaining catalyst residue are usually separated from the polypropylene produced in a post-treatment step. On the other hand, advances in process machinery technology have led to the production of polypropylene by gas phase polymerization. However, according to this gas phase polymerization method, amorphous low molecular weight polypropylene and catalyst residues are contained in the produced polypropylene product. These problems can be solved by polymerization using a highly active catalyst to reduce the content of low molecular weight polypropylene to an extent that does not affect the practical physical properties of polypropylene. However, when polypropylene produced by gas phase polymerization is processed into molded products, films, fibers, etc., a noticeable smoke is generated. At the same time, the heat resistance and weather resistance of the processed product are significantly reduced. As a result of studies conducted by the present inventors, it has been found that the cause of this is propylene oligomers having a considerably lower molecular weight (for example, a molecular weight of 1000 or less) than what is normally referred to as amorphous low-molecular-weight polypropylene. On the other hand, although it has become possible to reduce the contamination of catalyst residues by using a highly active catalyst, this is not sufficient for industrial use.
For example, polypropylene obtained by gas phase polymerization has very poor hue, heat resistance, and weather resistance, and is not suitable for commercial use. The purpose of the present invention is to solve the above-mentioned problems in the method for producing polypropylene using the gas phase polymerization method. An object of the present invention is to provide a manufacturing method. The method for producing polypropylene of the present invention involves the production of polypropylene by gas phase polymerization in the presence of a titanium trichloride composition and a catalyst system containing an organoaluminum compound.
_An organoaluminum compound represented by AlR _o Titanium trichloride composition obtained by reacting with titanium chloride and/or organic ether, 0.7 to 20 per 10,000 g of polypropylene produced
A system in which a catalyst consisting of mmol of organoaluminum and an electron-donating compound is prepolymerized with 0.01 g or more of propylene per 1 g of titanium trichloride composition at a temperature of 60°C or lower to produce a propylene polymer is used as a catalyst. It is characterized by being a system. The polymerization catalyst used in the present invention consists of a titanium trichloride composition, an organoaluminum, and an electron-donating compound. It does not matter in what form these components are present in this catalyst system. The titanium trichloride composition includes titanium trichloride obtained by reducing titanium tetrachloride with metal aluminum or an organoaluminium compound, a titanium trichloride composition obtained by pulverizing and activating the titanium trichloride composition,
, or a pulverized product of titanium trichloride and an electron-donating compound, which is obtained by reducing titanium tetrachloride in the presence of an organic ether compound and precipitating it from liquefied titanium trichloride, as a complexing agent. Examples include those obtained by reacting the solid obtained by treating with titanium tetrachloride. Specifically, a preferred titanium trichloride composition is produced by reacting titanium tetrachloride, an organic aluminum compound, and an organic ether, and then reacting titanium tetrachloride, an ether compound, or titanium tetrachloride and an ether compound. Examples include titanium trichloride compositions obtained by treatment with More specifically, a titanium tetrachloride is reduced with an organoaluminum compound, the reduced solid product obtained after removing excess titanium tetrachloride is reacted with an organic ether compound, and the unreacted organic ether is removed. b) a reaction product of an organoaluminum compound and an organic ether; A solid product obtained by reacting titanium chloride with an organic ether compound and titanium tetrachloride (for example, titanium trichloride composition B in Examples) c Titanium tetrachloride and an organic ether, reacted with an organoaluminum compound, and then reacted with an organic ether compound (for example, titanium trichloride composition C in Examples). What is important in the present invention is that the titanium trichloride composition has an average particle size (weight average particle size measured by wet method) in the range of 10 to 100μ, preferably about 30 to 80μ. It is preferable that the particle size distribution be as narrow as possible, and it is preferable that it does not contain ultrafine powder or coarse particles, or even if it does contain them, it should be very small (for example, 1% by weight of particles smaller than 1μ).
Below, 10% by weight or less of 300μ or larger). If the average particle size is smaller than the above range, fine catalyst and polymer powder will accumulate in the recycled gas piping from the gas phase polymerizer, making long-term continuous operation impossible, so it is not suitable. Furthermore, if particles with an average particle size larger than the above range are used, not only will the polymerization activity be markedly reduced, but also
This is not preferred because polypropylene containing a large amount of hydrocarbon-soluble components is produced. In addition, since the polypropylene obtained by the production method of the present invention usually contains live catalyst residues,
Usually, the catalyst residue is stabilized by feeding it into a stabilization step, but if the average particle size is larger than the range of the present invention, it is difficult to stabilize the catalyst residue in the stabilization step. _{The organoaluminum} compound of the present invention has the general formula AlR n
3). Specifically, triethylaluminum, tri-n-propylaluminum,
Tri-iso-propyl aluminum, tri-iso-
Examples include butylaluminum, diethylaluminium chloride, di-iso-butylaluminum chloride, diethylaluminium iodide, and the like. Moreover, a mixture of those selected from these can be used. The amount of organic aluminum compound used is per 1000 kg of polypropylene produced.
It is important to control the amount to 0.7 to 20 mmol, preferably 1 to 15 mmol, and more preferably 2 to 5 mmol. If it is less than 0.7 mmol, the amount of oligomer produced will be low, but the polymerization rate will be low, which is not preferable. 20m
If the amount exceeds mol, the amount of oligomer produced will not only increase significantly, but also the hue, heat resistance, and weather stability of the polypropylene produced will deteriorate significantly, which is not preferable. As the electron donating compound in the present invention, (a)
Ethers such as diethyl ether, di-n-butyl ether, diisoamyl ether, tetrahydrofuran, dioxane, diethylene glycol dimethyl ether, diphenyl ethers, (b)carboxylic acid esters such as methyl formate, ethyl acetate, ethyl benzoate, methyl toluate, (iii) Ketones such as ethyl toluate and methyl methacrylate, such as methyl ethyl ketone,
(d)aldehydes such as acetophenone, such as acetaldehyde, isobutyraldehyde, benzaldehyde, (f)amines, nitriles, acid amides such as diethylamine, aniline, acetonitrile, acrylamide, tetramethylurea, (h)phosphorus compounds, e.g. Examples include triphenylphosphine, triphenylphosphite, triphenylphosphate, and (tri)sulfur compounds such as carbon disulfide and methylphenylsulfone. The amount of the electron-donating compound used varies depending on the type, but when using the titanium trichloride composition (1), it is 1.95× per 1 g of the titanium trichloride composition.
10 ⁻³ to 9×10 ⁻² mmol, preferably 5×10 ⁻³ to 5
×10 ⁻² mmol is used. If the amount is less than 1.95×10 ⁻³ mmol per gram of the titanium trichloride composition, the polymerization activity is high, but the amount of oligomers produced increases, which is not preferable. In addition, the heat resistance and weather resistance of the produced polypropylene are poor. Moreover, if the amount exceeds 9×10 ⁻² mmol per gram of the titanium trichloride composition, the polymerization activity will be significantly lowered, which is not preferable. If it is outside the above range, the amount of oligomer produced will increase significantly, the polymerization activity will decrease significantly, or the heat resistance and weather stability of the polypropylene produced will decrease, which is not preferable. The catalyst system of the present invention comprises a titanium trichloride composition, 0.7 to 20 mmol of organoaluminium per 1000 g of produced polypropylene, and a catalyst consisting of an electron-donating compound at a temperature of 60°C or lower, at a temperature of 0.01 g per 1 g of the titanium trichloride composition. or more (preferably 0.01
~500g, most preferably 0.01~100g) to produce a propylene polymer. The propylene used in this prepolymerization treatment is preferably propylene alone, but propylene containing 3 mol% or less of ethylene or 10 mol% or less of α-olefin such as butene-1 may also be used. The feed rate of propylene in this pretreatment is not critical, but is 0.01 to 30 g/g (titanium trichloride composition).hr. In addition, the processing time is 1 minute to 8 hours.
Preferably, a range of 30 minutes to 4 hours can be selected. This prepolymerization treatment is carried out in a liquid phase in a batch or continuous manner. propane, n-pentane, n
- It is preferable to carry out the reaction in an inert hydrocarbon such as hexane or n-heptane, or in liquefied propylene to form a suspended catalyst system. The concentration of the suspended catalyst system slurry (catalyst and polymer produced in the pretreatment) after polymerization pretreatment is non-critical, but is in the range of 0.1 to 10% by weight. Polymerization pretreatment is performed in the presence or absence of hydrogen, but
The coexistence of hydrogen can control the molecular weight of the produced propylene polymer. From an industrial standpoint, the smaller the reactor for the polymerization pretreatment, the better. Pre-polymerization treatment of the catalyst has the effect of preventing fine powder from blowing up inside the polymerization vessel during the next gas phase polymerization. The gas phase polymerization of the present invention involves not only propylene homopolymerization, but also propylene and ethylene, propylene and α
-Olefins (butene-1, hexene-1, etc.),
It is also applied to random copolymerization of propylene, ethylene and α-olefin, and block copolymerization of propylene and ethylene (for example, Japanese Patent Application No. 175523/1982). It is necessary to select a gas phase polymerization concentration lower than the sintering temperature of the polypropylene powder produced. A specific gas phase polymerization temperature ranges from 35°C to 90°C, preferably from 40°C to 80°C, and more preferably from 50°C to 75°C. Polymerization pressure is generally 1 to 40℃ Kg/cm ² G,
Preferably a range of 10 to 30 kg/cm ² G is used.
The gas phase polymerization temperature needs to be higher than the dew point of the gas in the polymerization vessel. An increase in polymerization pressure increases the dew point. Polymerization time is generally 10 minutes to 10 hours, preferably
The duration ranges from 30 minutes to 5 hours. The molecular weight of the polypropylene produced in the present invention is controlled by coexisting hydrogen in the gas phase polymerization vessel, and MFR (230°C, 2.16 kg load, ASTM-D1238,
g/10 min) is generally in the range of 0.05 to 200. The monomer (propylene or propylene and α-olefin) used in the polymerization pretreatment and gas phase polymerization of the present invention can be optionally supplied in liquid or gaseous form during the polymerization period. As the polymerization vessel used in the production method of the present invention, a reactor equipped with a stirrer (for example, JP-A-51-86584,
A fluidized bed reactor or a known gas phase polymerization reactor can be used. The method for producing polypropylene by gas phase polymerization of the present invention solves the problems of conventional gas phase polymerization.
In other words, a well-balanced polypropylene with less oligomer formation and improved hue, heat resistance, and weather resistance stability can be produced. the result,
When processed into molded products, films, fibers, etc.
Similarly to when processing polypropylene obtained by slurry polymerization, the generation of fume during processing can be greatly reduced. By carrying out the present invention, polypropylene with a quality comparable to or higher than that of the slurry method can be obtained, and resources and energy can be saved compared to the slurry method. It is industrially important that such a process for producing polypropylene by gas phase polymerization can be provided. The present invention will be explained below with reference to Examples and Comparative Examples.
Titanium trichloride compositions used in Examples and Comparative Examples were prepared as follows. Preparation of titanium trichloride composition (A) Reactor with a stirrer of capacity 15 (rotation speed
200rpm), maintain a nitrogen atmosphere inside, add 2.7% of normal hexane and 0.69% of titanium tetrachloride,
Cooled to 0°C. Subsequently, 3.4 g of hexane and 0.78 g of diethyl aluminum chloride (hereinafter abbreviated as DEAC) were added at 0° C. over 4 hours. Thereafter, the mixture was stirred for 1 hour, and further stirred at 65°C for 1 hour to carry out the reaction, and then cooled to room temperature and allowed to stand still. The upper liquid phase was separated, and the solid in the sediment layer was washed five times with hexane. Next, add 9.8% hexane to the solid.
and diisoamyl ether 1.37 at 35°C
The reaction mixture was stirred for 100 minutes. After the reaction was allowed to stand, the supernatant liquid was separated and the solid product in the remaining sediment layer was washed with hexane. 3.9% hexane and 1.0% titanium tetrachloride were added over 60 minutes, stirred at 65°C for 2 hours, and allowed to stand still. After standing, the supernatant was removed, and the resulting precipitate was washed with hexane and dried under reduced pressure to obtain 1 kg of titanium trichloride composition (A). Preparation of titanium trichloride composition (B) 0.4 g mol of titanium tetrachloride (hereinafter simply expressed as mole) was placed in two glass reactors purged with nitrogen.
was heated and maintained at 35°C. To this titanium tetrachloride, add the following reaction solution: 60 ml of n-hexane,
DEAC 0.05 mol and diisoamyl ether 0.12
The molar mixture was mixed for 1 min at 25°C and then
The reaction product (diisoamyl ether/DEAC molar ratio: 2.4/1) reacted for 30 minutes was added dropwise at 35° C. for 30 minutes. The titanium tetrachloride reaction mixture was then kept at 35°C for 30 minutes, then raised to 75°C and reacted for 1 hour, resulting in a solid precipitate. The mixture was cooled to room temperature (20° C.) and allowed to stand to separate into a precipitate and a supernatant, and the reactor was tilted to remove the supernatant. Next, 400 ml of n-hexane was added to the precipitate after removing the supernatant, and after stirring and mixing for 10 minutes, the operation of removing the supernatant by decantation and decantation was repeated four times. After this treatment, the precipitate was evaporated to dryness under reduced pressure to remove coexisting n-hexane, yielding 19 g of a solid product. Next, the entire amount of this solid product was put into two glass reactors, 300 ml of n-hexane was added thereto, stirred and suspended, and 16 g of diisoamyl ether and 35 g of titanium tetrachloride were added at 20°C, and the mixture was heated at 65°C. Allowed time to react. After this reaction, the reaction mixture was cooled to room temperature and left to stand to separate a precipitate (hereinafter referred to as second precipitate), and the supernatant liquid was decanted and removed. Next, 400 ml of n-hexane was added to the second precipitate after removing the supernatant, and the operation of stirring and mixing for 10 minutes and removing the supernatant by decantation was repeated four times. This solid product was then dried under reduced pressure to obtain 15 g of titanium trichloride composition (B). Production of titanium trichloride composition (C) Monochlorobenzene with a monochlorobenzene concentration of 43 to 60 vol% in a 50 reactor equipped with a stirrer.
25 of n-heptane mixed solvent was introduced, and 2.4 of titanium tetrachloride was added. While stirring, 4.6 g of di-n-butyl ether was added dropwise over 10 minutes. The temperature was maintained at 20°C. Then diethyl aluminum chloride
1.4 was added dropwise over 40 minutes. After that, heat at a rate of 1℃/3 minutes, and when the temperature reaches 55℃, add more heat.
Butyl ether 1.0 was added dropwise over 30 minutes. The temperature at the end of the dropping was 65°C. Thereafter, the temperature was raised to 90°C to precipitate solid components, and the mixture was further stored for 30 minutes. The solid component was mixed with 10% of monochlorobenzene.
The mixture was washed three times with n-heptane 20 times and dried under reduced pressure at room temperature to obtain 3.5 kg of titanium trichloride composition (C) with a particle size of 10 to 120 μm. Measured values in Examples and Comparative Examples were determined by the following method. Yield: Yield (g) of polypropylene produced per gram of titanium trichloride composition Content of ethylene and butene-1 in copolymer: Measured by infrared spectrophotometry. Hexane or pentane extraction rate: Press the stabilized polypropylene powder at 190℃ to make a film, crush the film, and add 3g of sample (less than 20 mesh) to a Kumagawa extractor for 6 hours.
Extracted under refluxing hexane or pentane.
The extraction rate was determined from the weight change before and after extraction. Oligomer content: 20mg of stabilized polypropylene powder was heated at 260°C for 40 minutes to reduce the evaporated matter to 80%.
After cooling to below ℃, trap. Trapped substances are collected using a gas chromatograph (Flame).
Ionization Detector, column: Chromosorb W-HP impregnated with 10% Dexil300, 1m, condition 70℃
Hold for 1 minute, heating rate: 16℃/1 minute up to 330℃,
(detector temperature: 300°C) and determined from the area of the chromatogram chart. Al, Ti, Cl content: The polypropylene powder after stabilization treatment was measured by fluorescent X-ray method. YI (Yellow Index): 0.1% BHT and 0.1% calcium stearate were added to polypropylene powder after stabilization treatment, and granulated at 230°C. The pellets were measured using a color difference meter (manufactured by Suga Test Instruments Co., Ltd.). Heat resistance, weather resistance stability test: 0.1% BHT, 0.05% calcium stearate and 0.05% Irganox in polypropylene powder after stabilization treatment
1010 (manufactured by Ciba Geigy) was added and granulated at 230°C. A test piece was made from the pellet, and the heat resistance stability was tested at a temperature of 150℃ using a gear type heat aging tester.
It was evaluated by In addition, the weather stability is confirmed by Sunshine Weatherometer (black panel temperature 63℃).
The time required for clutch to occur was measured. Regarding the organoaluminum compounds shown in the table, DEAC is diethylaluminum chloride, and TEA is triethylaluminum. Further, in the electron-donating compound, E is diethylene glycol dimethyl ether, F is methyl methacrylate, and G is methyl p-toluate. Examples 1 to 4 1 Preparation of catalyst system A predetermined amount of purified normal hexane (hereinafter referred to as n-hexane) was put into a polymerization vessel with a stirrer and an internal volume of 3, which was purged with nitrogen gas, and diethylaluminum chloride, trichloride A titanium composition and an electron-donating compound are supplied in predetermined amounts in this order to form a catalyst liquid,
A predetermined amount of propylene gas was supplied while stirring with or without addition of hydrogen, and the treatment was carried out for a predetermined period of time to produce a propylene polymer to prepare a slurry-like catalyst system. The amount of n-hexane was controlled so that the slurry concentration was 1% by weight. The conditions are shown in Table 1. 2 Gas phase polymerization Horizontal polymerization vessel with stirring blade (L/D
= 6, internal volume 10, rotation speed 40 rpm) was thoroughly dried, and the inside was replaced with Chituso gas. The catalyst system in slurry form was continuously sprayed into the front of the polymerizer in the presence of a powder bed of the product polypropylene. At the same time, sufficiently purified and dried propylene was continuously supplied to carry out gas phase continuous polymerization. The molecular weight of the polypropylene produced was controlled by the hydrogen concentration in the gas phase of the polymerization vessel. Polymerization time was controlled by the level of the resulting polypropylene powder bed. The polymerization heat generated in the polymerization vessel was removed by adding liquefied propylene or liquefied olefin to the polymerization vessel. The reaction gas mixture vaporized in the polymerization vessel was extracted from the polymerization vessel through a recycle gas pipe, cooled by a heat exchanger, and liquefied. The conditions and results are shown in Table 1. 3 Stabilization treatment Most of the produced polymer powder, which is continuously discharged from the polymerization vessel at a rate of 900 g/hr, is fluidized (linear velocity was maintained at 10 cm/sec based on the sky tower standard. Subsequently, in a fluidized bed (2), 15 mol% of water,
A gas consisting of 0.5 mol% propylene oxide and 84.5 mol% nitrogen (linear velocity is 15 cm/sec based on the sky column)
It was fluidized and stabilized. Both fluidized beds were conducted at a temperature of 120°C. Table 1 shows the Al, Ti, Cl contents and YI of the polypropylene powder after stabilization treatment.

【table】

[Heat resistance, weather resistance stability test]

Heat resistance and weather resistance stability tests were conducted on the stabilized polypropylene powders of Example 1, Comparative Example 1, and Examples 6, 7, 8, and 9. The results are shown in Table 4.

【table】

【table】

【table】

【table】

【table】 [Brief explanation of drawings]

FIG. 1 is a flow sheet showing the manufacturing method of the present invention.

Claims (1)

[Claims] 1. When producing polypropylene by gas phase polymerization in the presence of a titanium trichloride composition and a catalyst system containing an organoaluminum compound, titanium tetrachloride and the general _formula AlR _o R is an alkyl group having 1 to 8 carbon atoms, X is a halogen group, and 2≦n≦3)
A titanium trichloride composition obtained by reacting the organoaluminum compound represented by the formula with an organic ether and further reacting it with titanium tetrachloride and/or an organic ether, per 1000 g of polypropylene produced.
A system in which a propylene polymer is produced by prepolymerizing a catalyst consisting of 0.7 to 20 mmol of organoaluminum and an electron-donating compound at a temperature of 60°C or lower with 0.01 g or more of propylene per 1 g of titanium trichloride composition. A method for producing polypropylene, the method comprising using as a catalyst system. 2 0.01 or more per 1 g of titanium trichloride composition,
The manufacturing method according to claim 1, wherein the process is performed using 500 g or less of propylene. 3 The particle size of the titanium trichloride composition is 10 to 100μ
The manufacturing method according to claim 1 or 2. 4. The manufacturing method according to claims 1 to 3, wherein the electron-donating compound is an organic ether or a carboxylic acid ester.