KR102140257B1 - Preparation method of homo polypropylene - Google Patents

Abstract

The present invention relates to a method for producing homo polypropylene that enables the production of a resin whose molecular weight distribution is controlled to a desired range while maintaining other physical properties such as molecular weight in a method for producing homo propylene to which the Spheripol process is applied. The production method of the homo polypropylene in the reaction system comprising a plurality of loop reactors, in the presence of a catalyst and hydrogen gas, in the production method of the homo polypropylene comprising the step of continuously polymerizing a propylene monomer in the liquid phase, the By controlling the supply concentration of hydrogen gas to a plurality of loop reactors, a homo polypropylene having a predetermined weight average molecular weight and molecular weight distribution (MWD) is produced.

Description

Manufacturing method of homo polypropylene {PREPARATION METHOD OF HOMO POLYPROPYLENE}

The present invention relates to a method for producing a homo polypropylene that enables the production of a resin whose molecular weight distribution is controlled to a desired range while maintaining other physical properties such as molecular weight, in a method for producing a homo polypropylene to which the Spheripol process is applied.

Various methods for producing homo polypropylene by polymerizing propylene have been proposed. Among them, the Spheripol process is a process for producing polypropylene introduced by LBI (Lyondell Basell), and consists of a process of bulk polymerization of liquid propylene in the presence of a catalyst or the like in a reaction system including a plurality of loop reactors. It is widely used worldwide.

In particular, this Spheripol process is an economical and simplified process that can produce polypropylene with various properties, has high reliability in equipment/process, and has high safety and eco-friendly characteristics, making it suitable for the production of various polypropylenes such as homo polypropylene. It is widely used.

Meanwhile, homo polypropylene is a resin applied to manufacture various products such as packaging materials, stationery, labels, various films or textile products, and is manufactured to have physical properties adjusted to an appropriate range according to specific products or uses to which these resins are applied. Needs to be. Accordingly, a method of preparing a homo polypropylene having various physical property ranges has been proposed by adjusting the type or supply amount of the (crude) catalyst and various other polymerization process conditions.

However, the previously known method was able to control the molecular weight itself or the melt index itself of the homo polypropylene, but a technique capable of controlling the molecular weight distribution of the homo polypropylene having a similar molecular weight to a desired range more precisely. It has not been properly proposed.

In particular, in recent years, as the level of required physical properties for resin products has increased and more precise control of required physical properties is required, the molecular weight distribution of homo polypropylene is more precisely suited to the level of desired rigidity, processability or impact strength. Although a technology that can be manufactured by adjustment has been required, the technical demand has not yet been properly met.

Accordingly, the present invention is to provide a method for producing homo polypropylene that enables the production of a resin whose molecular weight distribution is controlled to a desired range while maintaining other physical properties such as molecular weight, in a method for producing homo polypropylene to which the Spheripol process is applied.

In order to solve the above problems, the present invention is a method for producing a homo polypropylene in a reaction system including a plurality of loop reactors, in the presence of a catalyst and hydrogen gas, continuously polymerizing a propylene monomer in a liquid phase. in,

Hydrogen gas for each of the plurality of loop reactors is supplied at a concentration of 200 to 400ppm, homo polypropylene having a weight average molecular weight of 100,000 to 300,000 and a molecular weight distribution (MWD) of 2.5 to 3.5 is formed. Provides a manufacturing method.

The present invention also provides a method for producing a homo polypropylene in a reaction system comprising a plurality of loop reactors, in the presence of a catalyst and hydrogen gas, the step of continuously polymerizing a liquid propylene monomer.

Hydrogen gas for each of the plurality of loop reactors is supplied at a concentration of 30 to 150ppm, homo polypropylene having a homopolypropylene having a weight average molecular weight of 100,000 to 300,000 and a molecular weight distribution (MWD) of 2.0 to 2.5 is formed. Provides a manufacturing method.

Hereinafter, a method of manufacturing a homo polypropylene according to a specific embodiment of the present invention will be described.

According to one embodiment of the invention, in a reaction system comprising a plurality of loop reactors, in the presence of a catalyst and hydrogen gas, in the process of producing a homo polypropylene comprising the step of continuously polymerizing a propylene monomer in the liquid phase,

Hydrogen gas for each of the plurality of loop reactors is supplied at a concentration of 200 to 400ppm, homo polypropylene having a weight average molecular weight of 100,000 to 300,000 and a molecular weight distribution (MWD) of 2.5 to 3.5 is formed. A manufacturing method is provided.

Further, according to another embodiment of the invention, in the method of the above embodiment, hydrogen gas is supplied to each of the plurality of loop reactors at a concentration of 30 to 150 ppm, with a weight average molecular weight of 100,000 to 300,000 and a 2.0 to 2.5 A method of making a homo polypropylene from which a homo polypropylene having a molecular weight distribution (MWD) is formed is provided.

The present inventors in a method for producing homo polypropylene through a Spheripol process using a reaction system comprising a plurality of loop reactors, while maintaining different physical properties such as molecular weight, it is possible to produce a resin whose molecular weight distribution is adjusted to a desired range. Studies have been continued to confirm the manufacturing method and the process conditions.

As a result of this continuous study, by controlling the supply concentration of the hydrogen gas supplied to the plurality of loop reactors, the homopolypropylene whose molecular weight distribution is respectively controlled to a desired range, for example, 2.5 to 3.5, or 2.0 to 2.5 It was found that can be selectively produced and the invention was completed.

Although it has been known that the molecular weight range of the resin can be controlled by controlling the supply concentration of hydrogen gas, it is not known that only the molecular weight distribution can be adjusted to a desired range while maintaining the molecular weight range. Was confirmed.

Accordingly, according to embodiments of the present invention, homo polypropylene having physical properties such as a desired level of molecular weight and molecular weight distribution can be more precisely controlled and manufactured and provided, which can be applied to appropriate uses and products. For example, the above-mentioned molecular weight range and a homo polypropylene having a relatively narrow molecular weight distribution can be applied to applications and applications requiring a higher level of impact strength, and a homo polypropylene having a relatively wide molecular weight distribution. It can be applied to applications and applications requiring higher stiffness and excellent processability.

In the method for producing homo polypropylene according to the above-described embodiments of the present invention, the polymerization process is carried out according to the conventional process of the Spheripol process, in the reaction system including a plurality of loop reactors, the presence of catalyst and hydrogen gas Below, it can proceed by the method of polymerizing a liquid propylene monomer.

In addition, this polymerization step can be carried out by a method of bulk polymerization of the propylene monomer at 50 to 80°C, or 60 to 75°C, or 65 to 73°C.

And, through the method for producing the homo polypropylene, in order to more effectively obtain a homo polypropylene having a molecular weight and a molecular weight distribution range in the above-described range, a compound represented by the following Chemical Formula 1 can be preferably used as the catalyst:

[Formula 1]

In the above formula,

X is the same or different halogen from each other,

R ₁ is C _6-20 aryl substituted with C _1-20 alkyl,

R ₂ , R ₃ and R ₄ are each independently hydrogen, halogen, C _1-20 alkyl, C _2-20 alkenyl, C _1-20 alkylsilyl, C _1-20 silylalkyl, C _1-20 alkoxysilyl, C _1-20 ether, C _1-20 silyl ether, C _1-20 alkoxy, C _6-20 aryl, C _7-20 alkylaryl, or C _7-20 arylalkyl,

A is carbon, silicon, or germanium,

R ₅ is C _1-20 alkyl substituted with C _1-20 alkoxy,

R ₆ is hydrogen, C _1-20 alkyl, or C _2-20 alkenyl,

R ₇ and R ₈ are the same as or different from each other, and are straight-chain or branched-chain alkyl having 1 to 5 carbon atoms.

That is, by using such a catalyst, it is possible to effectively obtain a homo polypropylene having a weight average molecular weight of 100,000 to 300,000 and a molecular weight distribution of 2.0 to 3.5, and hydrogen gas at a concentration in the range described above in a Spheripol polymerization process using such a catalyst. By supplying to each loop reactor, it is possible to obtain homo polypropylene with a more precisely controlled molecular weight distribution range.

According to a more specific example, in order to more effectively obtain a homo polypropylene having a weight average molecular weight of 100,000 to 300,000 and a molecular weight distribution (MWD) of 2.5 to 3.5, according to the method of one embodiment described above, in Chemical Formula 1, R ₇ and R ₈ can more preferably use a catalyst that is a straight chain alkyl such as methyl.

In another embodiment, in order to more effectively obtain a homo polypropylene having a weight average molecular weight of 100,000 to 300,000 and a molecular weight distribution (MWD) of 2.0 to 2.5, according to the method of another embodiment described above, in Chemical Formula 1, R ₇ is a straight chain alkyl such as methyl, and R ₈ is a branched chain alkyl such as isopropyl, more preferably a catalyst.

On the other hand, in the catalyst of the formula (1), considering the polymerization activity, physical properties of the final produced homo polypropylene, etc., X is preferably chlorine, R ₁ is phenyl substituted with tert-butyl Preferred, R ₂ , R ₃ and R ₄ are preferably hydrogen. Further, it is preferable that A is made of silicone, R ₅ is 6-tert-butoxy-hexyl, and R ₆ is preferably made of methyl.

In a more specific example, according to the method of one embodiment, the catalyst that can be most preferably used to prepare a homo polypropylene having a molecular weight distribution (MWD) of 2.5 to 3.5 includes the compound of Formula 2 below, According to the method of another embodiment, the most preferred catalyst that can be used to prepare a homo polypropylene having a molecular weight distribution (MWD) of 2.0 to 2.5 is a compound of formula (3):

[Formula 2] [Formula 3]

On the other hand, the compounds of Formulas 1 to 3 described above can be easily prepared by a person skilled in the art by a method known in the art, for example, a method disclosed in Korean Patent Publication No. 2016-0045433, etc. Shall be

In addition, the catalyst of Formula 1 may be used together with a general carrier or a co-catalyst, such as a carrier such as silica, which has been conventionally used for the production and polymerization of homo polypropylene, boron or aluminum as the carrier or co-catalyst. Any co-catalyst can be used without any limitation.

In addition, according to the method of the above embodiment, in order to more effectively obtain a homo polypropylene having a molecular weight distribution (MWD) of 2.5 to 3.5, a reaction system including first and second loop reactors is used, and the first loop reactor is used. The hydrogen gas is supplied at a concentration of 200 to 400ppm, or 250 to 330ppm, and the second loop reactor is a hydrogen concentration at a concentration of at least 400ppm, more specifically, at a concentration of 300 to 390ppm. Can be supplied.

And, according to the method of the other embodiment, in order to more effectively obtain a homo polypropylene having a molecular weight distribution (MWD) of 2.0 to 2.5, using a reaction system including first and second loop reactors, the first loop reactor Hydrogen gas is supplied at a concentration of 30 to 150ppm, or 40 to 80ppm, and the second loop reactor is a hydrogen gas at a concentration of at least 150ppm, more specifically, at a concentration of 40 to 100ppm, in a second loop reactor Can be supplied.

Meanwhile, the homo polypropylene manufactured according to the above-described one embodiment or another embodiment may have a melt index of 25 to 35 g/10min (230°C, 2.16 kg).

As described above, the homo polypropylene has a constant melt index range and a molecular weight range at an appropriate level, and a more precisely controlled molecular weight distribution range according to supply conditions of hydrogen gas prepared according to one embodiment or another embodiment. Can have

In addition, the homo polypropylene may have a melting point of 145°C to 150°C when manufactured according to one embodiment, and may have a melting point of 151°C to 155°C when manufactured according to another embodiment.

As described above, according to the present invention, in the method for producing homo propylene to which the Spheripol process is applied, while maintaining other physical properties such as molecular weight or melt index, the molecular weight distribution or melting point is precisely controlled to a desired range. A method for producing homo polypropylene is provided.

Through the method of the present invention, since a homo polypropylene having more precisely controlled properties can be manufactured, it can be more appropriately applied to various uses and products.

Hereinafter, preferred embodiments are provided to help understanding of the present invention. However, the following examples are provided only for easier understanding of the present invention, and the contents of the present invention are not limited thereby.

Manufacturing example 1: Catalytic compound Manufacturing example

Step 1) Preparation of (6-tert-butoxyhexyl)(methyl)-bis(2-methyl-4-tert-butyl-phenylindenyl)silane

2-methyl-4-tert-butylphenylindene (20.0 g, 76 mmol) was dissolved in toluene/THF=10/1 solution (230 mL), followed by n-butyllithium solution (2.5 M, hexane solvent, 22 g) was slowly added dropwise at 0° C., and then stirred at room temperature for one day. Thereafter, (6-tert-butoxyhexyl)dichloromethylsilane (1.27 g) was slowly added dropwise to the mixed solution at -78°C, stirred for about 10 minutes, and then stirred at room temperature for one day. Then, water was added to separate the organic layer, and then the solvent was distilled under reduced pressure to obtain (6-tert-butoxyhexyl)(methyl)-bis(2-methyl-4-tert-butyl-phenylindenyl)silane.

¹ H NMR (500 MHz, CDCl ₃ , 7.26 ppm): -0.20-0.03 (3H, m), 1.26 (9H, s), 0.50-1.20 (4H, m), 1.20-1.31 (11H, m), 1.40 -1.62 (20H, m), 2.19-2.23 (6H, m), 3.30-3.34 (2H, m), 3.73-3.83 (2H, m), 6.89-6.91 (2H, m), 7.19-7.61 (14H, m)

Step 2) Preparation of [(6-tert-butoxyhexylmethylsilane-diyl)-bis(2-methyl-4-tert-butylphenylindenyl)]zirconium dichloride

The (6-tert-butoxyhexyl)(methyl)-bis(2-methyl-4-tert-butyl-phenylindenyl)silane prepared in Step 1 above was added to a toluene/THF=5/1 solution (95 mL). After dissolving, n-butyllithium solution (2.5 M, hexane solvent, 22 g) was slowly added dropwise at -78°C, followed by stirring at room temperature for one day. Bis(N,N'-diphenyl-1,3-propanediamido)dichlorozirconium bis(tetrahydrofuran)[Zr(C ₅ H ₆ NCH ₂ CH ₂ NC ₅ H ₆ )Cl ₂ (C ₄ H ₈ O) ₂ ] was dissolved in toluene (229 mL), then slowly added dropwise at -78°C and stirred at room temperature for one day. After the reaction solution was cooled to -78°C, HCl ether solution (1 M, 183 mL) was slowly added dropwise, followed by stirring at 0°C for 1 hour. After filtering and drying under vacuum, hexane was added and stirred to precipitate crystals. The precipitated crystals were filtered and dried under reduced pressure [(6-tert-butoxyhexylmethylsilane-diyl)-bis(2-methyl-4-tert-butylphenylindenyl)] zirconium dichloride (20.5 g, total 61) %).

¹ H NMR (500 MHz, CDCl ₃ , 7.26 ppm): 1.20 (9H, s), 1.27 (3H, s), 1.34 (18H, s), 1.20-1.90 (10H, m), 2.25 (3H, s) , 2.26 (3H, s), 3.38 (2H, t), 7.00 (2H, s), 7.09-7.13 (2H, m), 7.38 (2H, d), 7.45 (4H, d), 7.58 (4H, d ), 7.59 (2H, d), 7.65 (2H, d)

Step 3) Preparation of supported catalyst

After 3 g of silica was pre-weighed in a shrink flask, 24 mmol of methylaluminoxane (MAO) was added and reacted at 90° C. for 24 hours. After precipitation, the upper layer was removed and washed with toluene. 210 μmol of the ansa-metallocene compound synthesized above [(6-t-butoxyhexylmethylsilane-diyl)-bis(2-methyl-4-tert-butylphenylindenyl)] zirconium dichloride was added to toluene. After melting, it was reacted at 50°C for 5 hours. After the completion of the reaction and the precipitation was complete, the upper layer solution was removed, the remaining reaction product was washed with toluene, washed again with hexane, and dried in vacuo to obtain 5 g of a silica-supported metallocene catalyst in the form of solid particles.

Manufacturing example 2: of catalytic compounds Manufacturing example

Step 1) [6-(t-butoxy)hexyl]methylsilanediyl[2-isopropyl-1H-4-(4-tert-butyl)phenylindenyl] [2-methyl-1H-4-(4 -Tert-butyl)phenylindenyl] Preparation of zirconium dichloride

7-tert-butylphenyl-2-isopropylindene was added to a 250mL flask and dried under reduced pressure. Under an argon atmosphere, tert-butyl methyl ether anhydride was added and diluted, and then an n-BuLi 2.5M in hexane solution was gradually added at -25°C. After stirring at 25°C for 4 hours or more, Tsi was added to the reaction and stirred overnight. After adding THF 155 mL/mol and stirring again for 1 hour, the solvent was dried under reduced pressure, hexane was added to filter LiCl, and the filtrate was dried under reduced pressure.

In another 250 mL flask, 7-tert-butylphenyl-2-methylidene and CuCN were added and dried under reduced pressure. Under an argon atmosphere, tert-butyl methyl ether anhydride was added, diluted, and then n-BuLi 2.5M in hexane solution was gradually added at -25°C and stirred overnight. After extraction with MTBE and water, the solid was filtered through a vacuum filter and the liquid was distilled under reduced pressure to concentrate.

Tert-butylamine was added to a 100 mL flask, tert-butyl methyl ether anhydride was added under an argon atmosphere, diluted, and then added to another flask containing ZrCl ₄ ·2THF and toluene at -25°C, followed by 2 at 25°C. Stirred for more than an hour. The ligand prepared above was placed in another 100 mL flask and dried under reduced pressure. Under an argon atmosphere, toluene anhydride and THF were added and diluted, and then an n-BuLi 2.5M in hexane solution was gradually added at -25°C. This was stirred for 2 hours or more at 25°C, and the Zr-tert-butylamide solution synthesized previously at -25°C was added. After stirring at 25°C overnight, 1.0M in diethylether hydrochloric acid was added and stirred for 1 hour until 25°C. After drying the solvent under reduced pressure, the mixture was stirred in hexane, stirred, precipitated impurities for 2 hours or more, and then filtered to filter out LiCl and impurities. The filtrate was dried under reduced pressure, added to pentane, and recrystallized overnight at -30°C to [6-(t-butoxy)hexyl]methylsilanediyl[2-isopropyl-1H-4-(4-tert- Butyl)phenylindenyl] [2-methyl-1H-4-(4-tert-butyl)phenylindenyl] zirconium dichloride was prepared.

¹ H NMR (500 MHz, CDCl ₃ , 7.26 ppm): 1.05 (3H, d), 1.09 (3H, d), 1.20 (3H, s), 1.34 (9H, s), 1.50-1.93 (10H, m) , 2.27-2.31(1H, m), 3.37 (2H, t), 6.48 (1H, s), 6.98 (1H, s), 7.01 (1H, s), 7.09-7.12 (2H, m), 7.34~7.70 (12H, m)

Step 3) Preparation of supported catalyst

After 3 g of silica was previously weighed in a shrink flask, 39 mmol of methylaluminoxane (MAO) was added and reacted at 90° C. for 24 hours. After precipitation, the upper layer was removed and washed with toluene. The ansa-metallocene compound synthesized above [6-(t-butoxy)hexyl]methylsilanediyl[2-isopropyl-1H-4-(4-tert-butyl)phenylindenyl] [2-methyl -1H-4-(4-tert-butyl)phenylindenyl] After dissolving 270 μmol of zirconium dichloride in toluene, it was reacted at 50°C for 5 hours. After the completion of the reaction and the precipitation was complete, the upper layer solution was removed, the remaining reaction product was washed with toluene, washed again with hexane, and dried in vacuo to obtain 5 g of a silica-supported metallocene catalyst in the form of solid particles.

Example 1 to 5: Homo polymerization of propylene

The 2 L stainless Spheripol process reactor (including two loop reactors) was vacuum dried at 70° C., cooled, and 1.5 mmol of triethylaluminum, hydrogen gas, and 770 g of propylene were sequentially added at room temperature. After stirring for 10 minutes, 0.030 g of each supported catalyst prepared in Preparation Example 1 or 2 was dissolved in 20 mL of TMA-prescribed hexane and introduced into the reactor under nitrogen pressure. Then, the reactor temperature was slowly raised to 70°C, and then polymerized for 1 hour. After the reaction was completed, unreacted propylene was vented.

For reference, the types of supported catalysts used in each example and the concentrations of hydrogen gas supplied to each loop reactor were as summarized in Table 1 below.

Test example : Method for measuring physical properties of polymers

(1) Melting point (Tm) of the polymer: The melting point of the polymer was measured using a differential scanning calorimeter (DSC, device name: DSC 2920, manufacturer: TA instrument). Specifically, after heating the polymer to 220°C, the temperature was maintained for 5 minutes, and after cooling to 20°C again, the temperature was increased again. At this time, the rate of rise and fall of the temperature were respectively adjusted to 10°C/min. Did.

(2) Molecular weight distribution and weight average molecular weight (Mw) of the polymer: The weight average molecular weight (Mw) and number average molecular weight (Mn) of the polymer are measured using gel permeation chromatography (GPC). Then, the molecular weight distribution (PDI) was calculated by dividing the weight average molecular weight by the number average molecular weight. At this time, the analysis temperature was set to 160°C, trichlorobenzene was used as the solvent, and the molecular weight was measured by standardizing with polystyrene.

(3) Melt Index of Polymer: Measured under a load of 2.16 kg at 230° C. according to ASTM D1238, and calculated as the weight (g) of the polymer melted for 10 minutes.

The physical properties measured for the homo polypropylenes prepared in Examples 1 to 5 are collectively shown in Table 1 below.

Supported catalyst Hydrogen supply concentration in the first loop reactor
(ppm) Hydrogen supply concentration in the second loop reactor
(ppm) Melt Index
(g/10min) Mw Molecular weight distribution Tm Example 1 Preparation Example 1 300 300 29.1 182000 2.9 148.9 Example 2 Preparation Example 1 250 375 30.3 1790000 2.73 149.6 Example 3 Preparation Example 2 60 60 33.3 179000 2.33 152.9 Example 4 Preparation Example 2 45 45 29.2 182000 2.38 153.0 Example 5 Preparation Example 2 45 75 30.7 178000 2.13 153.5

As can be seen from Table 1, it was confirmed that by controlling the supply concentration of hydrogen gas supplied to a plurality of loop reactors, a homo polypropylene having a predetermined molecular weight distribution or the like can be produced.

Claims (11)

In a reaction system comprising a plurality of loop reactors, in the presence of a catalyst and hydrogen gas, in a process for producing a homo polypropylene comprising the step of continuously polymerizing a liquid propylene monomer,
Hydrogen gas was supplied to the plurality of loop reactors at a concentration of 200 to 400 ppm, respectively, with a weight average molecular weight of 100,000 to 300,000, a melt index of 25 to 35 g/10min (230° C., 2.16 kg), and 2.5 to 2.9. Homo polypropylene with molecular weight distribution (MWD) is formed,
The reaction system includes first and second loop reactors, hydrogen gas is supplied to the first loop reactor at a concentration of 200 to 400 ppm, and the second loop reactor has a supply concentration to the first loop reactor of 400 ppm or less. Hydrogen gas is supplied at a concentration,
The catalyst is a method for producing a homo polypropylene comprising a compound represented by the formula (1):
[Formula 1]

In the above formula,
X is the same or different halogen from each other,
R ₁ is C _6-20 aryl substituted with C _1-20 alkyl,
R ₂ , R ₃ and R ₄ are each independently hydrogen, halogen, C _1-20 alkyl, C _2-20 alkenyl, C _1-20 alkylsilyl, C _1-20 silylalkyl, C _1-20 alkoxysilyl, C _1-20 ether, C _1-20 silyl ether, C _1-20 alkoxy, C _6-20 aryl, C _7-20 alkylaryl, or C _7-20 arylalkyl,
A is carbon, silicon, or germanium,
R ₅ is C _1-20 alkyl substituted with C _1-20 alkoxy,
R ₆ is hydrogen, C _1-20 alkyl, or C _2-20 alkenyl,
R ₇ and R ₈ are methyl.
In a reaction system comprising a plurality of loop reactors, in the presence of a catalyst and hydrogen gas, in a process for producing a homo polypropylene comprising the step of continuously polymerizing a liquid propylene monomer,
Hydrogen gas for each of the plurality of loop reactors was supplied at a concentration of 30 to 150 ppm, with a weight average molecular weight of 100,000 to 300,000, a melt index of 25 to 35 g/10min (230° C., 2.16 kg), and 2.0 to 2.38. Homo polypropylene with molecular weight distribution (MWD) is formed,
The reaction system includes first and second loop reactors, hydrogen gas is supplied to the first loop reactor at a concentration of 30 to 150 ppm, and the second loop reactor has a supply concentration to the first loop reactor of 150 ppm or less. Hydrogen gas is supplied at a concentration,
The catalyst is a method for producing a homo polypropylene comprising a compound represented by the formula (1):
[Formula 1]

In the above formula,
X is the same or different halogen from each other,
R ₁ is C _6-20 aryl substituted with C _1-20 alkyl,
R ₂ , R ₃ and R ₄ are each independently hydrogen, halogen, C _1-20 alkyl, C _2-20 alkenyl, C _1-20 alkylsilyl, C _1-20 silylalkyl, C _1-20 alkoxysilyl, C _1-20 ether, C _1-20 silyl ether, C _1-20 alkoxy, C _6-20 aryl, C _7-20 alkylaryl, or C _7-20 arylalkyl,
A is carbon, silicon, or germanium,
R ₅ is C _1-20 alkyl substituted with C _1-20 alkoxy,
R ₆ is hydrogen, C _1-20 alkyl, or C _2-20 alkenyl,
R ₇ is methyl and R ₈ is isopropyl.
delete delete delete delete delete delete The method of claim 1, wherein the homo polypropylene has a melting point of 145°C to 150°C.
The method of claim 2, wherein the homo polypropylene has a melting point of 151°C to 155°C.
The method of claim 1 or 2, wherein the polymerization step is carried out by bulk polymerization at 50 to 80°C.