JPH0317846B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing a propylene copolymer. More specifically, the present invention relates to a method for producing a propylene copolymer with a high ethylene content, which has excellent transparency, improved impact resistance, low temperature brittleness, and heat sealability, in stable operation and in high yield. [Prior Art] Crystalline propylene/ethylene random copolymers containing a small amount of ethylene are widely used and processed into various films, hollow molded products, injection molded products, and the like. Propylene/ethylene random copolymers have improved transparency, impact resistance, and low-temperature brittleness compared to propylene polymers, and have good heat-sealing properties in the film field, so they are often used as a variety of packaging materials. It is used. [Problems to be solved by the invention] However, the propylene/ethylene random copolymers conventionally provided on the market cannot be said to be fully satisfactory in terms of quality, and depending on the application, impact resistance and low temperature A random copolymer with better brittleness, transparency, heat sealability, etc. is desired. Such random copolymers can be produced by increasing the ethylene content further than those currently available on the market, for example, by increasing the ethylene content to 4.
% or more, preferably 5% or more. However, when attempting to produce a propylene copolymer with a high ethylene content by slurry polymerization, the production of polymers soluble in the polymerization solvent increases.
Due to the polymerization system becoming viscous, the polymer concentration in the polymerization system cannot be increased, resulting in a decrease in productivity. In addition, polymers that are soluble in the polymerization solvent not only cause poor heat transfer due to adhesion to the inner wall of the reactor, but also cause a decrease in the bulk density of the polymer particles and worsening of their slipperiness, which can cause problems in the subsequent transfer process. It also causes problems with clogging, caking in the hopper, and the formation of lumps in the drying process. Therefore, in the production of a propylene/ethylene random copolymer by solvent method polymerization, there is a natural limit to the ethylene content that can be introduced into the copolymer.
The ethylene content can be up to 4% by weight without causing the above-mentioned major disadvantages. With such an ethylene content, the above-mentioned improvements in physical properties cannot be achieved. In recent years, a slurry polymerization method (so-called bulk polymerization method) using liquid propylene as a medium has been developed. Although some improvement can be expected with this method since the amount of dissolved soluble polymer is reduced, it is basically the same as the solvent polymerization method and does not lead to a sufficient solution. [Problems to be solved by the invention] The present inventors have developed an industrially advantageous method for producing a propylene-ethylene copolymer having excellent transparency, impact resistance, low-temperature brittleness, and heat sealability. In order to achieve this goal, as a result of intensive research focusing on improving powder properties and polymerization methods, the following method was discovered. That is, the present invention uses a specific highly active catalyst, performs the first stage copolymerization in liquefied propylene, and performs the second stage copolymerization in the gas phase, thereby achieving the above-mentioned production method and the resulting polymer. The present invention was achieved by successfully developing a manufacturing method that does not have the above drawbacks. That is, the purpose of the present invention is to provide excellent transparency,
When producing a propylene/ethylene copolymer that has impact resistance, low temperature brittleness, and heat sealability,
The amorphous polymer soluble in the polymerization solvent does not cause polymer adhesion in the reactor, adhesion of the powder during the drying process, or agglomeration, and the catalyst removal process can be simplified or omitted. It is an object of the present invention to provide a manufacturing method that allows stable continuous operation while providing a polymer with good powder properties. The gist of the present invention is to use a catalyst system in which the aluminum content is 0.15 or less in terms of the atomic ratio of aluminum to titanium, and the catalyst system is mainly composed of a solid titanium trichloride-based catalyst complex containing a complexing agent and an organoaluminium compound. ,
A method for producing a propylene copolymer having an ethylene content of 4% by weight or more by dividing polymerization into two stages, the method comprising: (a) random copolymerization of propylene and ethylene in the presence of liquefied propylene and hydrogen in the first stage; (b) In the second step, a random copolymer having an ethylene content of 1% to 5% by weight is produced in an amount of 50 to 95% by weight of the total copolymerization amount. In this process, random copolymerization of propylene and ethylene is carried out to produce a random copolymer with an ethylene content of more than 5% by weight and less than 20% by weight of the total amount of copolymer produced.
A method for producing a propylene-ethylene copolymer is provided. To further explain the present invention in detail, the solid titanium trichloride-based catalyst complex used as a catalyst in the present invention has an aluminum content of 0.15 or less in terms of the atomic ratio of aluminum to titanium, preferably
It is 0.1 or less, more preferably 0.02 or less, and contains a complexing agent. The content of the complexing agent is 0.001 or more in molar ratio of the complexing agent to titanium trichloride in the solid titanium trichloride-based catalyst complex.
Preferably it is 0.01 or more. Specifically, titanium trichloride, the formula AlR _P X _3-P (where R
is a hydrocarbon group having 1 to 20 carbon atoms, X is a halogen atom, and p is a number of 0≦p≦2). containing, for _example , _the formula _{TiCl 3} (AlR _P ≦p≦2, c is a complexing agent, s is a number of 0.15 or less, and t is a number of 0.001 or more),
Of course, in addition to _{the TiCl 3 component} , the _{AlR P} , an inorganic solid for a carrier such as MgO, and an olefin polymer powder such as polyethylene or polypropylene. Examples of the complexing agent C include ethers, thioethers, ketones, carboxylic acid esters, amines, carboxylic acid amides, and polysiloxanes, among which ethers, thioethers, and carboxylic acid esters are particularly preferred. Examples of AlR _P X _3-P include AlCl ₃ and AlRCl ₂ . In addition, the solid titanium trichloride-based catalyst complex used in the method of the present invention has an X-ray diffraction pattern at a position corresponding to the strongest peak position of α-type titanium trichloride (2θ=
Particularly preferred is one having a halo of maximum strength at around 32.9°). Further, it is preferable that the solid titanium trichloride-based catalyst complex is not subjected to thermal history at a temperature exceeding 150° C. during production. Furthermore, the solid titanium trichloride-based catalyst complex used in the method of the present invention has a pore radius of 20 Å or more as measured by a mercury porosimeter method.
Amorphous polymers are characterized by an extremely fine pore volume with a cumulative pore volume of 0.02 cm ³ /g or more between 500 Å, especially 0.03 cm ³ /g to ^{0.15 cm 3} /g. This is particularly preferred since it is not necessary to remove coalescence. However, such a solid titanium trichloride-based catalyst complex can be prepared from a liquid containing titanium trichloride liquefied in the presence of (a) ether or thioether at 150°C;
Precipitate at the following temperature. (b) Solid titanium trichloride obtained by reducing titanium tetrachloride with an organoaluminum compound or metal aluminum can be easily produced by treating it with a complexing agent and a halogen compound. The following two methods can be used to obtain a liquid material containing liquefied titanium trichloride in method (a). (A) A method in which titanium tetrachloride is used as a starting material and reduced with an organoaluminum compound in the presence of an ether or thioether and, if necessary, a suitable hydrocarbon solvent. (B) Using solid titanium trichloride as a starting material, if necessary in the presence of a suitable hydrocarbon solvent,
Method of treatment with ether or thioether. There are no particular restrictions on the method for precipitating a fine powder solid titanium trichloride catalyst complex from a liquid. 150℃,
Preferably 40-120℃, particularly preferably 60-100℃
The temperature is raised to ℃ to cause precipitation. Note that when the total number of moles of titanium and aluminum in the titanium trichloride liquid is smaller than the number of moles of ether or thioether, a liberating agent may be added to promote precipitation. The liberating agent has the function of precipitating free solid titanium trichloride by reacting with the complex of titanium trichloride and ether or thioether that constitutes the above liquid, and is more acidic than titanium trichloride. Examples of Lewis acids include titanium tetrachloride, boron trifluoride, boron trichloride, vanadium tetrachloride, aluminum trichloride, alkyl aluminum dihalides, alkyl aluminum sesquihalides, dialkyl aluminum halides, and the like. Among these, titanium tetrachloride, aluminum halides, such as aluminum trihalide,
Alkylaluminum dihalides and the like are preferred.
The amount of the liberating agent used is preferably 5 times the mole or less of titanium in the liquid material. As the complexing agent in the method (b), those exemplified above as complexing agent C can be similarly mentioned.
Examples of the halogen compound include titanium tetrachloride and carbon tetrachloride. The complexing agent treatment and the halogen compound treatment may be performed simultaneously, or the complexing agent treatment may be performed first and then the halogen compound treatment may be performed. The complexing agent treatment is usually carried out by adding a complexing agent to solid titanium trichloride in a diluent in an amount of 0.2 to 3 moles relative to TiCl ₃ at a temperature of -20 to 80°C. After the complexing agent treatment, it is preferable to separate and wash the obtained solid. Halogen compound treatment is usually carried out in a diluent at a temperature of -10 to 50°C. The amount of halogen compound used is usually 0.1 per TiCl ₃
~10 times by mole, preferably 1 to 5 times by mole. After the halogen compound treatment, it is preferable to separate and wash the obtained solid. Specific examples of these titanium trichloride manufacturing methods include Japanese Patent Publications No. 55-8452, No. 55-8451,
Publication No. 55-8452, Publication No. 55-8003, Publication No. 54-
Publication No. 41040, Publication No. 55-8931, Japanese Unexamined Patent Publication No. 1983-
Publication No. 36928, Publication No. 59-12905, Publication No. 59-13630
For example, the method described in No. On the other hand, the organoaluminum compound of the cocatalyst has the general formula AlR ¹ _o Cl _3-o (wherein R ¹ has a carbon number of 1 to 20
is a hydrocarbon group, n is a number from 1.95 to 2.10). Among them, diethylaluminum monochloride in which R ¹ is an ethyl group and n is 2 can also be used, but those in which R ¹ is a normal propyl group or a normal hexyl group are particularly preferred. Within this range, by polymerizing in combination with the solid titanium trichloride catalyst complex described above, results in both high polymerization activity and stereoregularity of the polymer can be obtained. Furthermore, when using n > 2.10, the decrease in stereoregularity is greater than the improvement in polymerization activity, while when using n < 1.95, on the other hand, the polymerization activity decreases more than the improvement in stereoregularity. is significant, giving unfavorable results in either case.
The organoaluminum compound that is the cocatalyst may have both a normal propyl group and a normal hexyl group as R ¹ in the above general formula. Therefore, the method for producing such an organoaluminum compound which is a cocatalyst may be a known method, for example, by reacting tri-n-propyl aluminum or tri-n-hexyl aluminum with aluminum trichloride; Normal propylaluminum, trinormalhexylaluminum or aluminum trichloride and (b) general formula
Produced by reacting with a compound represented by AlR ² _n Cl _3-n (wherein R ² represents a normal propyl group or a normal hexyl group, and m represents a number of 0<m<3). Ru. Furthermore, there is a method that combines these two methods, that is, first, tri-n-propyl aluminum or tri-n-hexyl aluminum is reacted with aluminum trichloride to produce, for example, AlR ² _n Cl _3-n where m is about 0.9 to 2.1. manufacture,
Next, a small amount of tri-n-propyl aluminum, tri-n-hexyl aluminum or aluminum trichloride is added to this to give the desired n, thereby producing the product. The reaction temperature during these reactions is room temperature or
150°C, usually 50°C to 100°C, and a reaction time of several minutes to several hours, usually 1 to 2 hours, is sufficient. Although the reaction does not require the use of a solvent, it is possible to use solvents such as aliphatic hydrocarbons such as n-hexane and n-heptane, aromatic hydrocarbons such as toluene and xylene, and alicyclic hydrocarbons such as cyclohexane and methylcyclohexane. You can go in their presence. In addition, when trialkylaluminum having an alkyl group different from R ² in AlR ² _n Cl _3-n is used as a reactant added in the second stage reaction, normal hexyl group and normal propyl group are A compound having both is obtained. After the reaction is completed, it may be used as a cocatalyst as it is, but it is preferable to purify it by distillation under reduced pressure or the like. Furthermore, in the method of the present invention, in addition to the above catalyst and cocatalyst, an electron donating compound may be used as the third catalyst component to improve the stereoregularity of the produced polymer without reducing the polymerization activity. Such electron-donating compounds include one electron-donating atom or group.
Compounds containing more than one compound, such as ethers, polyethers, alkylene oxides, furans, amines, trialkylphosphines, triarylphosphines, pyridines, quinolines, phosphoric esters,
Examples include phosphoric acid amide, phosphine oxide, trialkyl phosphite, triarylphosphite, ketone, carboxylic acid ester, and carboxylic acid amide. Among these, preferred are carboxylic acid esters such as ethyl benzoate, methyl benzoate, phenyl acetate, and methyl methacrylate, glycine esters such as dimethylglycine ethyl ester and dimethylglycine phenyl ester, triphenyl phosphite, and trinonyl phenyl. Examples include triarylphosphites such as phosphites. The ratio of each catalyst component used is usually selected from the range of 1:1 to 100, preferably 1:2 to 40, based on the molar ratio of titanium trichloride to organoaluminum compound in the solid titanium trichloride catalyst complex. When the aforementioned third catalyst component is used, the molar ratio of titanium trichloride to the third catalyst component is selected to be 1:0.01 to 10, preferably 1:0.05 to 2. Furthermore, aromatic hydrocarbons such as benzene, toluene, and xylene may also be used as the third catalyst component. Note that the solid titanium trichloride-based catalyst complex used as a catalyst may be used as it is for polymerization, but
It is preferable to pre-treat with a small amount of olefin such as propylene or ethylene in the presence of an organoaluminum compound before use. This pretreatment is effective in improving the physical properties of the polymer slurry, such as bulk density. Pretreatment is performed at a temperature lower than the polymerization temperature, generally from 20℃
At 60°C, titanium trichloride of the polymer/solid titanium trichloride catalyst complex produced by pretreatment = 0.1 ~
The ratio is 50/1 (weight ratio), usually 1 to 20/1. In the method of the present invention, polymerization is carried out in two stages in a method for producing a propylene-ethylene copolymer using a catalyst system mainly consisting of a solid titanium trichloride-based catalyst complex and an organoaluminum compound as described above. However, in the first step, random copolymerization of propylene and ethylene is carried out in the presence of liquefied propylene. Here, in order to supply the solid titanium trichloride catalyst complex and organoaluminum compound into the polymerization tank, aliphatic hydrocarbons such as hexane and heptane, alicyclic hydrocarbons such as cyclohexane, and aromatic hydrocarbons such as benzene and toluene are used. It is preferred to use inert liquid hydrocarbons as diluents, and it is therefore within the scope of the invention for trace amounts of these inert liquid hydrocarbons to coexist with the liquefied propylene. The polymerization temperature and polymerization time are selected so that the amount of the propylene and ethylene copolymer is 50 to 95% by weight of the total copolymer produced. Polymerization temperature is usually
The temperature is selected from the range of 40 to 100°C, preferably 55 to 80°C. The polymerization pressure is the sum of the vapor pressure of liquefied propylene determined by the polymerization temperature, the pressure of hydrogen used as a molecular weight regulator, and the vapor pressure of a small amount of the inert liquid hydrocarbon used as a diluent for the catalyst component, but usually 25 ~40Kg/ ^cm2 . The melt flow index of the random polymer of propylene and ethylene obtained in the first stage (230℃, load 2.16
Extrusion rate in kg/10 min, according to ASTM D1238-70. In the following, it will be abbreviated as MFI. ) is 1~
Select the polymerization temperature and amount of molecular weight regulator so that the molecular weight is 30%. Examples of the molecular weight modifier include hydrogen, dialkylzinc, etc., but hydrogen is preferred. Typically, the hydrogen concentration in the gas phase is about 1-15 mole percent. The propylene and ethylene copolymer produced in the first step has an ethylene content of 1% by weight as determined by ¹³ C-NMR analysis in order to ensure good properties, efficient and stable operation of the resulting polymer. 5% by weight or more
The following is preferable. Further, the first stage polymerization reaction may use one polymerization reactor or two or more reactors. Next, in the second step, random copolymerization of propylene and ethylene is carried out in the gas phase in the presence of a mixed gas of the propylene copolymer produced in the first step and hydrogen, propylene, and ethylene. The ethylene content in the copolymer produced at this stage is more than 5% by weight.
The monomer composition is adjusted to be 20% by weight or less, and adjusted to be in the range of 5 to 50% by weight of the total amount of copolymer produced. If the ethylene content in the second stage exceeds 20% by weight, the powder properties of the resulting polymer deteriorate, resulting in adhesion to the vessel wall and formation of agglomerates.
Furthermore, even if the amount of polymerization in the second stage is more than 50% by weight of the total polymerization amount, the content of amorphous polymer will increase, resulting in polymer adhesion in the reactor, polymer sticking during the drying process, and agglomeration. This is not desirable because it causes On the other hand, the second
If the amount of polymerization in the step is too small, the effects of improving impact resistance, heat sealability, etc. will not be sufficient. Polymerization temperature is usually 25-100℃, preferably 25-90℃
Selected from the range of °C. If the temperature exceeds 100°C, the resulting propylene/ethylene copolymer will have poor free-flowing properties, and sticking between polymer particles and formation of lumps will occur, which is undesirable. The polymerization pressure is usually preferably 5 to 30 kg/cm ² . The MFI of the propylene/ethylene random copolymer can be controlled by the polymerization temperature and the amount of hydrogen, which is a molecular weight regulator. Polymerization may be carried out continuously or batchwise. In a continuous system, a separate polymerization vessel is used for each stage, with the transfer of the polymer slurry between the polymerization vessels conveniently being based on pressure differences. Therefore, it is preferable to determine the polymerization pressure so that the pressure in the polymerization tank is such that the pressure in the first stage is greater than the second stage. It is also possible to increase the pressure in the first stage by adding an inert gas such as nitrogen or argon. The propylene/ethylene random copolymer obtained by the method of the present invention has excellent powder properties, and there is no need to remove the amorphous polymer. And, even without removing the amorphous polymer, it has excellent impact resistance, transparency,
It has low temperature brittleness and heat sealability. Furthermore, in the method of the present invention, the amount of propylene/ethylene random copolymer produced is as high as 16,000 g, and even more than 22,000 g, per gram of titanium trichloride. Therefore, the titanium trichloride residue remaining in the polymer is less than 19 ppm of titanium, and furthermore,
It becomes less than 14ppm and there is no need to remove it anymore. After the second stage of polymerization, the propylene/ethylene random copolymer is separated from unreacted monomer gas,
Either directly pelletize as is, or in order to remove chlorine in the catalyst residue, polymer powder and a small amount of gaseous alkylene oxide are mixed at 80 to 120°C for several minutes as shown in JP-A-52-25888. It can be pelletized after a simple process of gas-solid contact, or it can be made into a final product as it is as a powder grade without pelletizing. In order to operate the method of the present invention stably and continuously for a long period of time,
The powder properties of the catalyst-containing olefin polymer powder in the polymerization system were determined to have a bulk density of 0.35 g/cc at a temperature of 30 to 130°C.
or more, preferably 0.40g/cc or more, angle of repose 30~
50°, preferably 30 to 45°, and a sliding angle of 25 to 50°,
Preferably, the angle is 25 to 43°, and the average particle size is 100μ or more.
Preferably, the thickness is 200μ or more. In order to obtain such a powdery polymer powder, it is sufficient to use a solid titanium trichloride-based catalyst complex produced by the method (a) or (b) described above, especially the method (a). . [Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded. In addition, the meanings of the abbreviations in the examples and various measurement methods are as follows. Catalyst efficiency CE (g/g) is the amount of copolymer produced in grams per gram of titanium trichloride. The n-hexane extraction residue (%) is the residual amount (% by weight) when extracted with boiling n-hexane for 3 hours using an improved Soxhlet extractor. The bulk density ρ _B (g/cc) was based on JIS-6721. The angle of repose was measured using a three-wheel cylindrical rotation method angle of repose measuring instrument manufactured by Tsutsui Rikagaku Kikai Co., Ltd. during rotation. Melt flow index MFI (g/10) is
According to ASTM D1238-70, the extrusion rate of the polymer at 230°C and a load of 2.16 kg is shown. The embrittlement temperature Tb (°C) was determined according to ASTM D746 for a test piece punched from a 2.0 mm thick flat plate made using a 1 oz injection molding machine. The ethylene content in the polymer was determined by ¹³ C-NMR spectroscopy. The ethylene content in the second stage polymerization was calculated from the ethylene content of the total polymer and the ethylene content in the first stage polymerization. Haze shall be measured in accordance with ASTM D1003-61.
The test was carried out on a 0.25mm press sheet. Further, FIG. 1 is a flowchart diagram to help understand the technical content included in the present invention, and the present invention is not limited to the following embodiments unless it exceeds the gist thereof. Example 1 (A) Preparation of solid titanium trichloride catalyst complex 5.0 moles of purified toluene and 5.0 moles of titanium tetrachloride were charged into an autoclave with a capacity of 10 which was sufficiently purged with nitrogen, and further 5.0 moles of di-n-butyl ether were added. When 2.38 mol of diethylaluminum chloride was added dropwise to this while stirring and maintaining the temperature at 25 to 30°C, a blackish brown homogeneous solution of titanium trichloride was obtained. Next, the temperature of the homogeneous solution of titanium trichloride was raised to 40°C and maintained for 2 hours. During this process, a purple titanium trichloride precipitate was observed to form. At this point, 1.6 mol of titanium tetrachloride and 0.57 mol of tridecyl methacrylate were further added, the temperature was raised to 98°C, and stirring was continued for 2 hours. Thereafter, the precipitate was separated and washed repeatedly with n-hexane to obtain a finely divided purple solid titanium trichloride catalyst complex. Elemental analysis reveals that the catalyst complex has a composition of _the formula TiCl ₃ .(AlCl ₃ ) _0.007 [( _n -C ₄ H ₉ ) ₂ O] _{0.046 [ CH 2} . Was. In addition, using CuKα radiation, the X
When the line diffraction spectrum was measured, it had a halo with maximum intensity at 2θ = 32.9°. Further, the cumulative pore volume measured using a mercury porosimeter was 0.04 cm ³ /g when the pore radius was between 20 and 500 Å. (B) Production of titanium trichloride containing propylene polymer 0.25 g of purified n-hexane was placed in a 500 ml flask that had been sufficiently purged with dry nitrogen, and 1.9 g of diethylaluminum chloride and the solid titanium trichloride catalyst complex obtained in (A) above were added to TiCl. After charging 2.5g as _{step 3} , add 12.5g of propylene gas while stirring at 40℃.
Contact treatment was carried out by blowing into the gas phase for a minute. Next, the solid component was allowed to settle, and the supernatant liquid was removed by decantation, and washed several times with n-hexane to obtain a propylene polymer-containing solid titanium trichloride. (C) Production of propylene/ethylene copolymer 1.3 mmol of cocatalyst di-n-propylaluminum monochloride and 0.02 mmol of methyl methacrylate as the third component were placed in an autoclave with a capacity of 2 that was sufficiently purged with dry nitrogen, and then heated with hydrogen gas. Pour a specified amount of ethylene gas and liquefy propylene.
After charging 700g, the temperature of the autoclave was raised, and when the internal temperature reached 60℃, the propylene polymer-containing solid titanium trichloride catalyst component obtained in (B) above was added.
20mg of TiCl ₃ was injected under pressure to start the polymerization reaction. During the polymerization, each composition of the gas phase was analyzed and controlled by gas chromatography to be constant. 3
After the time polymerization, unreacted propylene was immediately purged, and 50 g of the polymer powder was sampled under a purified nitrogen atmosphere. This product had an ethylene content of 4.2% by weight, a boiling n-hexane extraction residue of 96% by weight, a bulk density of 0.46 g/cc, and an angle of repose of 35 degrees. Subsequently, hydrogen and a propylene/ethylene mixed gas were supplied to this reactor, and the gas phase polymerization reaction was continued at 70° C. for 2 hours while adjusting the pressure to 25 kg/cm ² G. After the reaction is complete, purge unreacted monomer gas,
342 g of powdered propylene/ethylene copolymer was obtained. Table 1 shows the polymerization conditions and various measurement results. The ethylene content of the copolymer powder after the second stage polymerization was 5.2% by weight, and the boiling n-hexane extraction residue was
It had a bulk density of 86% by weight, 0.47g/cc, and an angle of repose of 38 degrees. Fluorescence X in the first stage polymer and final polymer
From the Ti content determined by line analysis, the second
The proportion of the stage copolymer was 32.5% by weight, and the ethylene content of the second stage copolymer determined from the weight fraction was 7.3% by weight. That is, even if the ethylene content was increased in the subsequent copolymerization, the angle of repose of the polymer powder did not change and a powder with high bulk density was obtained. The embrittlement temperature of the pelletized product made by adding a heat stabilizer to the above polymer is -9℃, the melting point is 133℃, and the MFI
(230°C, 2.16Kg) was 9.2g/10 minutes, and the haze of the 0.25mm press sheet was 9.0%. Example 2 A propylene-ethylene copolymer was obtained in the same manner as in Example 1, except that the monomer gas composition and hydrogen concentration in the first and second stages were changed as shown in Table 1. Table 1 shows the various measurement results. Examples 3 and 4 Polymerization was carried out in the same manner as in Example 1, except that the polymerization time in the second stage and the amount of propylene-ethylene copolymer and ethylene content were changed. Table 1 shows the various measurement results. Comparative Example 1 In Example 1, in order to achieve the same ethylene content as the final copolymer of Example 1 through only the first stage polymerization, the ethylene fraction in the gas phase composition was increased and the first stage copolymer was Only polymerization was performed, and after predetermined batch polymerization, propylene and ethylene were purged to obtain a copolymer. The results are shown in Table 1. Although the ethylene content was the same as that of the total copolymer of Example 4, the bulk density was 0.35 g/cc, the angle of repose was 51 degrees, and the n-hexane extraction residue was 80.8% by weight. The condition is bad, and
The polymer had poor free flow properties. Comparative Example 2 In Example 1, the first stage polymerization and intermediate sampling were carried out in the same manner as in Example 1, and then the second stage
Stepwise polymerizations were carried out in liquid propylene. The amount of ethylene in the gas phase composition during the second stage polymerization was controlled so that the ethylene content in the entire copolymer was the same as in Example 1, and the copolymerization was carried out at a polymerization temperature of 60°C for 2 hours. . The results are shown in Table 1. Although the ethylene content in the entire copolymer was the same as in Example 1, the bulk density was
The powder properties were 0.38 g/cc, the angle of repose was 50 degrees, the residue after n-hexane extraction was 82.1%, and the powder properties were the worst.
In addition, it is considered impossible to actually manufacture it because of its high tackiness.

[Table] Example 5 (A) Production of solid titanium trichloride catalyst component 50 moles of toluene, 50 moles of titanium tetrachloride and 50 moles of di-n-butyl ether are added to an autoclave having a capacity of 100 and sufficiently purged with nitrogen. this
While maintaining the temperature at 25°C, 24 mol of diethylaluminum chloride was added to obtain a brown homogeneous solution. Next, when the temperature was raised to 40℃, a purple fine-grained solid was observed to precipitate after 30 minutes, but it remained as it was.
After holding at 40°C for 2 hours, 16 moles of titanium tetrachloride and 5.7 moles of tridecyl methacrylate were added.
The temperature was raised to 98°C and stirring was continued for 2 hours. Thereafter, the precipitate was separated and washed repeatedly with n-hexane to obtain a finely divided purple solid titanium trichloride catalyst complex. Next, 125 g of n-hexane was charged into a 200 capacity autoclave which was sufficiently purged with nitrogen, and 16 moles of di-n-propylaluminum chloride and 2500 g of the above solid titanium trichloride catalyst complex as TiCl ₃ were charged with stirring. Adjust the internal temperature to 30℃ and blow in propylene gas while stirring, and the amount of propylene is 12.5Kg.
Continue blowing until reaching . Thereafter, the solid was separated and washed repeatedly with n-hexane to obtain polypropylene-containing titanium trichloride (titanium-containing solid catalyst component). (B) Production of propylene/ethylene random copolymer A device consisting of a reaction tank with a capacity of 800 with a stirrer and a gas phase reactor with a capacity of 700 with a helical type stirrer connected in series was used. In the first stage reaction tank, liquid propylene was used as a solvent, and the titanium-containing solid catalyst component obtained in (A) above,
diethylaluminum chloride as a cocatalyst,
Methyl methacrylate as the third component, _H2 gas as the molecular weight regulator, and ethylene as the comonomer are continuously reacted at a predetermined ratio so that the ethylene content in the first stage polymer is 4% by weight. A propylene/ethylene random copolymer was produced by adjusting the amount of propylene supplied so that the polymerization temperature was 60° C. and the residence time was 3 hours. The above copolymer slurry was continuously supplied to the second stage gas phase reactor, and the pressure of the reactor was set to 25 Kg/cm ² , and the gas composition was such that ethylene/(ethylene + propylene) was 4.5 mol% by gas chromatography. In addition, while adjusting _H2 to have a predetermined molecular weight, hydrogen,
Gas phase polymerization was carried out by circulating a mixed gas of ethylene and propylene. The temperature of the gas phase reactor was adjusted to 70°C by adjusting the temperature of the circulating mixed gas. In addition, the copolymer supplied from the first stage is continuously extracted while adjusting the retention amount so that the residence time in the second stage gas phase reactor is 3 hours, and the powdered copolymer is extracted. Obtained. The ethylene content of the copolymer produced in the first stage reactor is 4% by weight, and the ethylene content of the copolymer produced in the second stage gas phase polymerization vessel is 8% by weight. The gas composition was adjusted while continuously analyzing the gas composition. Continuous operation was carried out in this manner for 15 days, during which time stable operation was achieved without any troubles such as blockages caused by lumps or decreases in heat transfer coefficient due to adhesion to the reactor walls. Furthermore, after the operation was completed, the reactor was opened and inspected, but no adhesion to the internal vessel wall or presence of lumps was observed. The copolymer extracted from the second stage gas phase reactor had a high bulk density and a small angle of repose, and was in powder form that was easy to handle. Table 2 shows typical examples of the results of this operation, the properties of the powder, and the basic physical properties of the obtained copolymer. Comparative Example 3 Copolymerization of ethylene and propylene was carried out in the same manner as in the first stage of Example 5, using only the first stage reactor without using the gas phase reactor of Example 5. The slurry was flushed with propylene in a propylene evaporator to obtain a polymer. Gas phase ethylene/(ethylene + propylene) was added so that the ethylene content in the copolymer was 6% by weight.
The ratio was adjusted. After 15 hours from the start of continuous polymerization, the heat transfer coefficient of the reactor began to decrease, and the copolymer powder extracted tended to stick together and become coarse. In addition, the bulk density was as low as 0.35 g/cc, resulting in poor natural flowability. After 28 hours of continuous polymerization, the reaction was stopped, and when the reactor was dismantled and inspected, rubber-like substances were found all over the inner surface of the reactor. Also, a large amount of rubbery material was found adhering to the inside of the evaporator. The obtained copolymer had poor powder properties and was difficult to handle, but its basic physical properties were equivalent to those of Example 5, commensurate with the ethylene content.

〔Effect of the invention〕

According to the present invention, a propylene copolymer with a high ethylene content that has excellent transparency, improved impact resistance, low temperature brittleness, and heat sealability can be produced in stable operation and in high yield, making it possible to produce industrially. It is useful for

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing one embodiment of the present invention.

Claims (1)

[Scope of Claims] 1. A catalyst system which has an aluminum content in an atomic ratio of aluminum to titanium of 0.15 or less and is mainly composed of a solid titanium trichloride-based catalyst complex containing a complexing agent and an organoaluminum compound. use,
A method for producing a propylene copolymer having an ethylene content of 4% by weight or more by dividing polymerization into two stages, the method comprising: (a) random copolymerization of propylene and ethylene in the presence of liquefied propylene and hydrogen; (b) In the second step, a random copolymer having an ethylene content of 1% to 5% by weight is produced in an amount of 50 to 95% by weight of the total copolymer produced. Random copolymerization of ethylene is performed to produce a random copolymer with an ethylene content of more than 5% by weight and less than 20% by weight of the total amount of copolymer produced.
Manufacture. A method for producing a propylene copolymer, characterized in that: 2. The solid titanium trichloride-based catalyst complex has the formula AlR _P X _3-P (wherein R is a hydrocarbon group having 1 to 20 carbon atoms, X is a halogen atom, p is a number of 0≦p≦2) in terms of molar ratio to aluminum halide and titanium trichloride.
The method for producing a propylene copolymer according to claim 1, which contains 0.001 or more of a complexing agent. 3 As a solid titanium trichloride catalyst complex, the pore radius is 20 Å to 500 Å measured by mercury porosimeter method.
The method for producing a propylene copolymer according to claim 1 or 2, wherein a propylene copolymer having a cumulative pore volume of 0.02 cm ³ /g or more is used. 4. Claims 1 to 4, wherein the solid titanium trichloride-based catalyst complex is precipitated at a temperature of 150°C or less from a liquid containing titanium trichloride liquefied in the presence of an ether or thioether. A method for producing a propylene copolymer according to any one of Item 3. 5. A patent claim in which the solid titanium trichloride-based catalyst complex is obtained by treating solid titanium trichloride obtained by reducing titanium tetrachloride with an organoaluminum compound or metal aluminum by treating it with a complexing agent and a halogen compound. A method for producing a propylene copolymer according to any one of items 1 to 3.