JPH0380808B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for producing a propylene-ethylene block copolymer. More specifically, the present invention relates to a method for producing a block copolymer by producing a polypropylene-based polymer and then copolymerizing propylene and ethylene without deactivating the catalyst. [Prior art] Propylene and other α-olefins are copolymerized in the second stage in the presence of the propylene polymer produced in the first stage using a so-called Ziegler-Natsuta catalyst consisting of titanium trichloride and an organoaluminum compound. A method for obtaining a heteroblock copolymer is known. Conventionally used titanium trichloride is, for example, one obtained by reducing titanium tetrachloride with an organoaluminum compound, one obtained by reducing it with metallic aluminum, or one obtained by heat treatment or pulverization treatment. There are also those obtained by treating the titanium trichloride obtained above with a complexing agent and further heat-treating it in titanium tetrachloride.
Although these catalysts have been variously improved, they are still insufficient in terms of polymerization activity and stereoregularity. On the other hand, as a polymerization method for block copolymers,
A slurry polymerization method carried out in the presence of a diluent such as an inert liquid hydrocarbon, a bulk polymerization method carried out in liquefied propylene, a gas phase polymerization method carried out in a gas phase, or an appropriate combination of these polymerization methods, for example, 1
There is also a method in which the first stage is carried out by bulk polymerization and the second stage is carried out by gas phase polymerization. However, when producing a propylene block copolymer by the above polymerization method using the titanium trichloride catalyst described above, the polymerization activity of the catalyst is low and the amount of polymer produced per unit amount of catalyst is small. that it needs to be removed from the polymer, and
The stereoregularity is low, the amount of amorphous polymer by-product is large, and especially when propylene-ethylene copolymerization is performed, the powder properties are significantly deteriorated, causing adhesion to vessel walls and equipment, and problems between polymer particles. This results in aggregation, formation of lumps, etc., and industrially, stable continuous operation becomes impossible. On the other hand, the physical properties of block copolymers are such that they significantly improve the impact strength and low-temperature brittleness that are disadvantageous to propylene homopolymers without significantly impairing the high rigidity of propylene homopolymers. The higher the stereoregularity of the polypropylene in the first stage is, the more desirable it is, and the more desirable the propylene-ethylene copolymer part in the second stage is, the more amorphous it is, and the more its amount is. However, as mentioned above, in conventional polymerization methods, the stereoregularity of the catalyst is insufficient and the amount of soluble amorphous polymer by-produced is large, resulting in deterioration of slurry and powder properties. It has been difficult to stably produce sufficient block copolymers due to physical properties such as limited production ranges. [Problems to be Solved by the Invention] The present inventors have made industrially advantageous block copolymers that have high rigidity, high impact strength, and excellent low-temperature brittleness, which are the physical properties of block copolymers. In order to develop a production method, we conducted intensive studies focusing on improving powder properties and polymerization methods.We found that using a specific highly active catalyst, the first stage of polymerization was carried out in liquefied propylene, and the second stage was By carrying out the propylene-ethylene copolymerization in the gas phase, the amount of amorphous polymer produced as described above can be reduced, the catalyst removal process can be simplified or omitted, and the powder characteristics of the resulting polymer can be improved. Moreover, the propylene/(propylene + ethylene) ratio and the hydrogen/(propylene + ethylene) ratio in the second stage can be very good.
By specifying the polymerization ratio (ethylene) and polymerization temperature and using hydrogen as a molecular weight regulator at each stage to set the melt flow index of the resulting polymer to a specific value, we can achieve excellent quality, that is, high rigidity and high impact. The present invention was achieved by discovering that a polymer having high strength and low embrittlement temperature as well as excellent surface condition (roughness) of melt extrudates can be obtained. [Means for Solving the Problems] The gist of the present invention is to provide a solid titanium trichloride-based catalyst complex containing an aluminum content in an atomic ratio of aluminum to titanium of 0.15 or less and a complexing agent, and an organic aluminum. A method for producing a propylene-ethylene block copolymer by dividing the polymerization into two stages using a catalyst system mainly consisting of a compound, the method comprising: (a) polymerizing propylene in the presence of liquefied propylene and hydrogen in the first stage; to produce a propylene homopolymer which accounts for 70% to 95% by weight of the total polymer production and has a melt flow index of 1 to 150; (b) In the second step, propylene/(propylene + ethylene ) is 50 mol% to 85 mol%,
25°C to 100°C in the presence of hydrogen with a hydrogen/(propylene + ethylene) ratio of 0.1 mol% to 30 mol%
Then, propylene and ethylene are copolymerized in the gas phase, and the amount of the total polymer produced is 5% to 30% by weight, and the melt flow index is 10 ^-7 to 30% by weight.
The present invention relates to a method for producing a propylene-ethylene block copolymer, which is characterized in that a propylene-ethylene copolymer having a block copolymer of 0.1 is produced. The present invention will be explained in detail below. The solid titanium trichloride-based catalyst complex used as a catalyst in the present invention has an aluminum content in which the atomic ratio of aluminum to titanium is 0.15 or less, preferably 0.1 or less, more preferably 0.02 or less, and contains a complexing agent. It is something to do. The content of the complexing agent is 0.001 or more, preferably 0.01 or more in molar ratio of the complexing agent to titanium trichloride in the solid titanium trichloride-based catalyst complex. Specifically, titanium _trichloride , ^the formula AlR ¹ _p halogen atom, p
represents a number of 0≦p≦2) containing a complexing agent in a molar ratio of 0.001 or more to aluminum halide and titanium trichloride, such as those of the formula
^TiCl _{3 ・} ⁽ _{AlR 1 p}
~20 hydrocarbon group, X is a halogen atom, p is a number of 0≦p≦2, C is a complexing agent, s is a number of 0.15 or less, t is a number of 0.001 or more Of course, in addition to the TiCl ₃ component, the _AlR ¹ _p It may be entirely substituted with iodine or bromine, or it may contain an inorganic solid for a carrier such as MgCl ₂ or MgO, or an olefin polymer powder such as polyethylene or polypropylene. Examples of the complexing agent C include ether, thioether, ketone, carboxylic acid ester, amine, carboxylic acid amide, polysiloxane, etc. Among these, ether,
Particular preference is given to thioethers or carboxylic acid esters. Examples of AlR ¹ _p X _3-p include AlCl ₃ and AlR ¹ Cl 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 are those 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) Easily produce solid titanium trichloride obtained by reducing titanium tetrachloride with an organoaluminum compound or metal aluminum by a method such as treatment with a complexing agent and treatment with a halogen compound. I can do it. 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) A method in which solid titanium trichloride is used as a starting material and is treated with ether or thioether in the presence of a suitable hydrocarbon solvent as necessary. The ether or thioether used may be of the general formula R ² -O-R ³ or R ² -S-R ³ (wherein,
R ² and R ³ represent a hydrocarbon group having 15 or less carbon atoms. ) in the antecedent expression.
R ² and R ³ are ethyl, n-propyl, n-
Alkyl groups such as butyl, n-amyl, n-hexyl, n-heptyl, n-octyl, n-decyl, n-dodecyl, preferably linear alkyl groups; alkenyl groups such as butenyl and octenyl, preferably linear Alkenyl group; examples include aryl groups such as tolyl, xylyl and ethyl phenyl, and alkyl groups such as benzyl. Preferred are dialkyl ethers, dialkenyl ethers, alkyl alkenyl ethers, dialkyl thioethers, and the like. In addition, as a hydrocarbon solvent, n-pentane,
n-hexane, n-heptane, n-octane, n
- Saturated aliphatic hydrocarbons such as dodecane and liquid paraffin; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene, etc., and are selected appropriately depending on the type of ether. be done. for example,
In the general formula shown above as an ether or thioether
When at least one of R ² and R ³ is an alkyl group or alkenyl group having 3 to 5 carbon atoms,
Preferably, aromatic hydrocarbons are selected, followed by alicyclic hydrocarbons, and when using an ether in which R ² and R ³ are alkyl groups or alkenyl groups having 6 or more carbon atoms, saturated aliphatic hydrocarbons are preferably selected. selected. Next ^, as an organoaluminum compound in method (A), for example, the general formula _AlR ⁴ _q
(X represents a halogen atom) is used, and the amount used is shown in the molar ratio of titanium in titanium tetrachloride to hydrocarbon group (R ⁴ in the general formula) in the organoaluminum compound. , 1:0.1
~1:50, preferably 1:0.3~1:10. The amount of ether or thioether used is
The molar ratio of ether: titanium tetrachloride is 1:0.05~
The ratio is 1:5, preferably 1:0.25 to 1:2.5. The method of conducting the reduction reaction is arbitrary, and usually 0 to 50
The three components are brought into contact in any order at a temperature on the order of °C to form a liquid. In addition, a small amount of titanium tetrachloride, for example, at a molar ratio of titanium tetrachloride to titanium tetrachloride.
When about 0.005 to 0.3 of iodine, titanium tetraiodide, or titanium tetrabromide is added, the solid titanium trichloride catalyst complex obtained by precipitation becomes a particularly highly active and highly stereoregular polymer. This is preferable because it gives As solid titanium trichloride in method (B), titanium trichloride produced by reducing titanium tetrachloride with hydrogen gas, aluminum, etc. can also be used, but titanium trichloride produced by reducing titanium tetrachloride with an organoaluminum compound can also be used. Particularly preferred is titanium trichloride. The amount of ether or thioether used is a molar ratio of titanium trichloride:ether or thioether of 1:1 or more, preferably 1:1 to 5. Ether or thioether treatment is usually carried out at 0 to 100°C, preferably at 20 to 50°C.
It is carried out at a temperature of around ℃. In method (a), a fine particulate solid titanium trichloride-based catalyst complex is precipitated at a temperature of 150°C or less from a liquid material containing titanium trichloride liquefied by either method (A) or (B) above. However, there are no particular restrictions on the method, and the liquid material may be heated as is or after adding a hydrocarbon diluent as necessary, at a temperature of 150℃ or less,
The temperature is usually raised to 20 to 150°C, preferably 40 to 120°C, and particularly preferably 60 to 100°C to precipitate. 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 reacting with the complex of titanium trichloride and ether or thioether constituting the liquid material to precipitate free solid titanium trichloride,
Lewis acids that are more acidic than titanium trichloride, e.g.
Titanium tetrachloride, boron trifluoride, boron trichloride,
Examples include vanadium tetrachloride, aluminum trichloride, alkyl aluminum dihalide, alkyl aluminum sesquihalide, dialkyl aluminum halide, and the like. Among these, titanium tetrachloride,
Aluminum halides, such as aluminum trihalides and alkyl aluminum dihalides, 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 complexing agent treatment,
It is preferable to separate and wash the obtained solid. Halogen compound treatment is usually carried out in a diluent between -10 and 50
Perform at a temperature of °C. The amount of the halogen compound used is usually 0.1 to 10 times, preferably 1 to 5 times by mole, relative to TiCl ₃ . After treatment with halogen compounds,
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 ⁵ _o Cl _3-o (wherein R ⁵ has a carbon number of 1 to 20
(representing a hydrocarbon group, n represents a number from 1.95 to 2.10) is used. One of these days
Diethylaluminum monochloride in which R ⁵ is an ethyl group and n is 2 can also be used, but it is particularly preferable that R ⁵ is a normal propyl group or a normal hexyl group. If n is within this range, high polymerization activity and stereoregularity of the polymer can be obtained by polymerizing in combination with the solid titanium trichloride catalyst complex described above. Furthermore, when n>2.10 is used, the decrease in stereoregularity is greater than the improvement in polymerization activity, while when n<1.95 is used, the polymerization activity is decreased more than the improvement in stereoregularity. The decrease is significant, giving unfavorable results in either case. Note that the organoaluminum compound that is the cocatalyst may have both a normal propyl group and a normal hexyl group as R ⁵ 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 ⁶ _n Cl _3-n (wherein R ⁶ 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 ⁶ _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 ⁶ in AlR ⁶ _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 ethyl benzoate, methyl benzoate, phenyl acetate, ethyl carboxylates such as 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 in 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 block copolymer using a catalyst system mainly composed of a solid titanium trichloride-based catalyst complex and an organoaluminum compound as described above. However, in the first step, propylene is homopolymerized 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 preferable to use inert liquid hydrocarbons as diluents, such as inert liquid hydrocarbons, 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 time are selected so that the amount of propylene homopolymer is 70 to 95% by weight of the total polymer produced. The polymerization temperature is usually selected from the range of 40 to 100°C, preferably 55 to 80°C. The polymerization pressure is the vapor pressure of liquefied propylene determined by the polymerization temperature,
This is the sum of the pressure of hydrogen used as a molecular weight regulator and the vapor pressure of a trace amount of the inert liquid hydrocarbon used as a diluent for the catalyst component, but it is usually 30 to 40.
Kg/ ^cm2 . The melt flow index of the propylene homopolymer obtained in the first stage (extrusion rate g/10 min at 230°C and load 2.16 kg,
According to ASTM D1238−70. In the following, it will be abbreviated as MFI. ) is 1 to 150, the polymerization temperature is
Select the amount of molecular weight modifier. 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 to 30 mole percent. Next, in the second step, propylene-ethylene random copolymerization is performed in the presence of the propylene homopolymer produced in the first step and a mixed gas of propylene and ethylene. The propylene/(propylene+ethylene) ratio is selected from the range of 50 to 85 mol%. Propylene/(propylene + ethylene) ratio is 50
~85 mol% is the condition where the amount of amorphous polymer by-product is maximized, but it is also the condition where the impact strength of the final polymer is improved the most, and even under such conditions, the present invention can be applied. According to this method, a block copolymer powder with high bulk density and excellent free-flowing properties can be obtained with almost no adhesion to the walls of the reaction tank. Outside the above range, the improvement in impact strength is insufficient and is not preferred. When polymerization is carried out at a propylene/(propylene + ethylene) ratio of 50 to 85 mol%, the propylene contained in the resulting propylene-ethylene random copolymer is 30 to 70% by weight (22 to 61 mol%). Become. The amount of propylene-ethylene random copolymer is 5 to 30% by weight of the total polymer production.
The polymerization temperature and time are selected so that If this amount is less than 5% by weight, the effect of improving impact strength etc. will be small, and if it exceeds 30% by weight, the bulk density and free flow properties will deteriorate, the rigidity and transparency will be greatly reduced, and the shrinkage rate of the molded product will also increase, so it is preferable. do not have. The polymerization temperature is usually selected from the range of 25 to 100°C, preferably 25 to 90°C. If the temperature exceeds 100°C, the resulting propylene-ethylene block copolymer will have poor free-flowing properties, resulting in agglomeration between polymer particles, adhesion to vessel walls, formation of lumps, etc., which is undesirable. Polymerization pressure is usually 10 to 40 kg/cm ² . and MFI of propylene-ethylene random copolymer
The polymerization temperature and the amount of hydrogen, which is a molecular weight regulator, are selected so that 10 ^-7 to 0.1. Usually, the hydrogen concentration is 0.1 to 30 mol% in hydrogen/(propylene + ethylene) ratio. If MFI exceeds 0.1, the improvement in impact strength will be insufficient. In addition, if the MFI is extremely small, for example less than 10 ^-7 , the impact strength will be greatly improved, but the balance effect during injection molding will become large, dimensional stability will deteriorate, and the molded product will have rough skin or This is undesirable because it causes eyelids. Polymerization is carried out continuously or batchwise. In the continuous system, a separate polymerization vessel is used for each stage, the transfer of the polymer slurry between the polymerization vessels being conveniently carried out by means of 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 block copolymer obtained by the method of the present invention has high crystallinity and the amount of amorphous polymer produced is small, so there is no need to remove the amorphous polymer. Moreover, it has excellent impact strength, rigidity, and low-temperature brittleness even without removing the amorphous polymer. In addition, in the method of the present invention, the amount of propylene-ethylene block copolymer produced is 16,000 g or even 22,000 g per 1 g of titanium trichloride.
It is so high that it exceeds. Therefore, the titanium trichloride residue remaining in the polymer is less than 19 ppm of titanium, and even less than 14 ppm, and there is no need to remove it any longer. After the second stage of polymerization, the propylene-ethylene block 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 made into pellets 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 being made into pellets. In order to operate stably and continuously for a long period of time in the method of the present invention, the powder properties of the catalyst-containing olefin polymer powder in the polymerization system must be adjusted to a bulk density of 0.35 at a temperature of 30 to 130°C.
g/cm ³ or more, preferably 0.40 g/cm ³ or more, angle of repose
30~50° preferably 30~45°, average particle size 100μ
The thickness is preferably 200μ or more.
In order to obtain such a powdery polymer powder, the above-mentioned (a) or (b) must be used as the solid titanium trichloride catalyst complex.
It is sufficient to use the product manufactured by the method (a), 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. 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 flowchart diagram unless it exceeds the gist thereof. In addition, the meanings of the abbreviations in the examples and various measurement methods are as follows. Catalytic efficiency DE (g/g) is the amount of copolymer produced in grams per gram of titanium trichloride. The isotactic index (%) is the residual amount (% by weight) after extraction with boiling n-hexane for 3 hours in a modified Soxhlet extractor.
Since the amorphous polymer is soluble in boiling n-hexane, the percentage (%) indicates the yield of the crystalline polymer. 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 min) 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 first yield strength YS (Kg/cm ² ) is ASTM D638-72
It was determined by a tensile test of a dumbbell piece punched from a press sheet with a thickness of 1.0 mm in accordance with the above. Unless otherwise specified, values are measured at 20°C. Izotsu impact strength (Kg-cm/cm) is ASTM
Measurements were made using D256 on a notched strip cut out from a 5.0 mm thick press sheet. Unless otherwise specified, values are at 20°C. The embrittlement temperature T _b (°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 second stage MFI was calculated using the formula below. log (MFI) ₂ = {log (MFI) _w - (1-x) log (MFI) ₁ }/X (MFI) ₂ : Second stage calculation MFI (MFI) _w : MFI of the entire block copolymer ( (Actual measurement) (MFI) ₁ : MFI of the first stage (actual measurement) x: Weight ratio of the second stage polymer to the total block polymer Example 1 (A) Preparation of solid titanium trichloride catalyst complex Sufficiently purged with nitrogen Purified toluene 5.0 and titanium tetrachloride 5.0 in an autoclave with a capacity of 10
mol and further di-n-butyl ether
5.0 mol was added. Stir this at 25°C to 30°C.
While maintaining the temperature at °C, 2.38 mol of diethylaluminum chloride was added dropwise to obtain a blackish brown homogeneous solution of titanium trichloride. 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, more titanium tetrachloride
1.6 mol and 0.57 mol 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. Elemental analysis reveals that the catalyst complex has the formula _TiCl3 .( _AlCl3 ) _0.007 [(n- _{C4H9 ) 2O} ] _0.046 [ _CH2
-C( _CH3 ) _{COOC13H27 ]} It had a composition of _0.015 . In addition, using CuKα radiation, the X
When the line diffraction spectrum was measured, 2θ=32.9°
had a halo of maximum intensity. 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 propylene-ethylene block copolymer 1.3 mmol of cocatalyst di-n-propylaluminium monochloride was added to hydrogen gas in an induction stirring autoclave with a capacity of 2 and sufficiently purged with dry nitrogen.
1.2Kg/cm ² and 700g of liquefied propylene were charged. The temperature of the autoclave was raised, and when the internal temperature reached 70°C, 20 mg of the solid titanium trichloride catalyst component obtained in (A) above was injected as TiCl ₃ under pressure with nitrogen to start the polymerization reaction. After 3 hours, unreacted propylene was immediately purged, and 20 g of polymer powder was sampled under a purified nitrogen atmosphere. Subsequently, hydrogen and propylene-ethylene mixed gas are supplied to this reactor, and the pressure is 15 Kg/cm ² G, and the gas composition becomes propylene/(propylene + ethylene) = 65 mol% and hydrogen/(propylene + ethylene) = 0.51 mol%. The gas phase polymerization reaction was continued at 80°C for 1.5 hours while adjusting the temperature accordingly. After the reaction was completed, unreacted monomer gas was purged to obtain 325 g of powdered propylene-ethylene block copolymer. Table 1 shows the polymerization conditions and various measurement results.
The bulk density (ρ _B ) of the copolymer powder was 0.45 g/cc and was 98.3, but these values were
It can be said that the decrease in bulk density is smaller than that of the propylene homopolymer extracted at the end of the stage. The angle of repose was also good at 36°. On the other hand, in terms of physical properties, both the first yield strength and the Izot impact strength are high, and the embrittlement temperature is low. Examples 2 to 4 Propylene-
An ethylene block copolymer was obtained. Various measurement results are shown in Table 1. Examples 5 to 7 Polymerization was carried out in the same manner as in Example 1, except that the polymerization time in the second stage was changed and the amount of propylene-ethylene copolymer was changed. Various measurement results are shown in Table 1. Comparative Example 1 In Example 1, the monomer gas composition and hydrogen concentration in the second stage were changed as shown in Table 2,
A propylene-ethylene block copolymer was obtained in the same manner as in Example 1 except that the polymerization time was changed. Various measurement results are shown in Table 2. When the propylene concentration was set to 45 mol% as the monomer gas composition in the second stage, the impact strength was insufficient. Comparative Examples 2 and 3 In Example 1, the polymerization time in the second stage was changed and the amount of propylene-ethylene copolymer was changed to 4.
Polymerization was carried out in the same manner as in Example 1, except that the amounts were changed to 35% by weight, and the results shown in Table 2 were obtained. From this, it can be seen that at 4% by weight, the effect of improving impact strength and the like is small, and at 35% by weight, the powder properties deteriorate significantly, making industrial production impossible. Comparative Example 4 Using the solid titanium trichloride catalyst complex obtained in Example 1(A), propylene homopolymerization in liquefied propylene was followed by propylene-ethylene copolymerization in liquefied propylene to obtain a block copolymer. Manufactured. That is, in the same manner as in Example 1, after performing the first stage homopolymerization and sampling the polymer powder, hydrogen gas and liquefied propylene were added again.
500 g was charged, the internal temperature was quickly controlled at 50°C, and ethylene gas was charged at 10.5 kg/cm ² to start propylene-ethylene copolymerization. Then the temperature
Ethylene partial pressure is 10.5Kg/cm ² while controlling at 50℃
Continuously supply ethylene gas so that
The polymerization reaction continued for 0.5 hours. The average gas composition in the gas phase during this period was propylene/(propylene+ethylene)=66 mol% and hydrogen/(propylene+ethylene)=2.6 mol%. After the polymerization reaction is completed, unreacted monomers are purged,
A propylene-ethylene block copolymer was obtained. The various measurement results are shown in Table 2, and the bulk density of the polymer powder was low at 0.38 g/cc, and the angle of repose was also poor at 48°. In particular, the surface of the powder particles was sticky, and when force was applied to the powder particles, the particles tended to stick together, and good fluidity like the powders obtained in Examples was not observed. Comparative Example 5 In Example 1, in place of the solid titanium trichloride catalyst complex obtained in Example 1(A), 150 mg of commercially available AA-titanium trichloride (TiCl ₃ 1/3 AlCl ₃ , manufactured by Stouffer) and A second stage propylene-ethylene copolymerization was carried out in liquefied propylene at 40 DEG C. using 5 mmol of di-n-propylaluminum monochloride. That is, after the first stage of polymerization is completed, unreacted monomers are purged, a portion of the polymer powder is sampled, and then hydrogen gas and liquefied propylene 500
g was charged, and the temperature was raised to 40°C. Here, ethylene gas was charged and the gas composition in the gas phase was adjusted so that propylene/(propylene + ethylene) = 65 mol% and hydrogen/(propylene + ethylene) = 4.4 mol%, and propylene-ethylene copolymerization was carried out. started. Thereafter, the polymerization reaction was continued while continuously supplying ethylene, and after 0.5 hours, unreacted monomers were purged to obtain a propylene-ethylene block copolymer. The various measurement results are shown in Table 2, and the polymer powder had poor free-flowing properties, was a cohesive powder, and contained many lumps. Furthermore, adhesion of rubbery substances was observed on the inner wall of the autoclave. In terms of physical properties, the first yield strength was low and the physical property balance was poor.

【table】

【table】

〔Effect of the invention〕

The propylene-ethylene block copolymer obtained by the method of the present invention has high crystallinity and the amount of amorphous polymer produced is small, so there is no need to remove the amorphous polymer. Moreover, it has excellent impact strength, rigidity, and low-temperature brittleness even without removing the amorphous polymer. In addition, the method of the present invention is industrially useful because such a propylene-ethylene block copolymer can be obtained with high activity.

[Brief explanation of drawings]

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

Claims (1)

[Scope of Claims] 1. The transition metal component consists mainly of a solid titanium trichloride-based catalyst complex and an organoaluminum compound, the aluminum content of which is 0.15 or less in terms of the atomic ratio of aluminum to titanium, and which contains a complexing agent. Using a catalyst system with a general formula as an organometallic component,
Using a compound represented by AlR ⁵ _o Cl _3-o (in the formula, R ⁵ represents a hydrocarbon group having 1 to 20 carbon atoms, and n represents a number from 1.95 to 2.10), polymerization was divided into two stages. A method for producing a propylene-ethylene block copolymer, comprising: (a) polymerizing propylene in the presence of liquefied propylene and hydrogen in the first step to produce a propylene block copolymer of 70% to 95% by weight of the total amount of polymer produced; producing a propylene homopolymer having a melt flow index of 1 to 150; (b) in the second step, the ratio of propylene/(propylene + ethylene) is 50 mol% to 85 mol%;
25°C to 100°C in the presence of hydrogen with a hydrogen/(propylene + ethylene) ratio of 0.1 mol% to 30 mol%
When propylene and ethylene are copolymerized in the gas phase, the amount of the total polymer produced is 5% to 30% by weight, and the melt flow index is 10 ^{-7 to} 30% by weight.
A propylene-ethylene copolymer with a concentration of 0.1 is produced. A method for producing a propylene-ethylene block copolymer, characterized in that: 2 The solid titanium trichloride-based catalyst complex has the formula AlR ¹ PX _3-P (wherein R ¹ is a hydrocarbon group having 1 to 20 carbon atoms , X is a halogen atom,
The block copolymer according to claim 1, which contains a complexing agent in a molar ratio of 0.001 or more to aluminum halide and titanium trichloride, where p is a number of 0≦p≦2. Manufacturing method. 3 As a solid titanium trichloride catalyst complex, the pore radius is 20 Å to 500 Å measured by mercury porosimeter method.
3. The method for producing a block copolymer according to claim 1 or 2, which uses a block copolymer having a cumulative pore volume of 0.02 cm ³ /g or more. 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 block 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 block copolymer according to any one of items 1 to 3.