阅读说明：本技术 负载型茂金属催化剂和使用该催化剂制备聚丙烯的方法 (Supported metallocene catalyst and method for preparing polypropylene using the same ) 是由 郑载晔 权宪容 洪大植 全相珍 于 2018-12-21 设计创作，主要内容包括：本发明涉及包含具有优异聚合活性的新型茂金属化合物的负载型催化剂,以及包括在催化剂的存在下使丙烯聚合的聚丙烯的制备方法。本发明的负载型茂金属催化剂可以生产具有相对窄的分子量分布和SPAN值的聚丙烯。(The present invention relates to a supported catalyst comprising a novel metallocene compound having excellent polymerization activity, and a method for preparing polypropylene comprising polymerizing propylene in the presence of the catalyst. The supported metallocene catalysts of the present invention can produce polypropylene having a relatively narrow molecular weight distribution and SPAN value.)

1. A supported metallocene catalyst comprising:

a metallocene compound represented by the following chemical formula 1, and

a carrier, a carrier and a water-soluble polymer,

[ chemical formula 1]

Wherein, in chemical formula 1,

n is an integer of 4 to 10,

R₁and R₂Are the same as or different from each other, and are each independently an aryl group having 6 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms substituted with an alkyl group having 1 to 20 carbon atoms;

R₃is an alkyl group having 1 to 20 carbon atoms;

R₄a tertiary amine having an alkyl group having 1 to 10 carbon atoms;

a is carbon, silicon or germanium; and

each X is the same or different from each other, and each is independently a halogen or an alkyl group having 1 to 20 carbon atoms.

2. The supported metallocene catalyst according to claim 1,

wherein R in chemical formula 1₄Is dimethylamine, dipropylamine, diisopropylamine, diphenylamine, methylpropylamine, methylaniline or isopropylaniline.

3. The metallocene-supported catalyst according to claim 1,

wherein the compound represented by chemical formula 1 is one of the compounds represented by the following structural formula,

4. the supported metallocene catalyst according to claim 1, further comprising one or more cocatalyst compounds selected from the group consisting of compounds represented by the following chemical formula 2, chemical formula 3, or chemical formula 4,

[ chemical formula 2]

-[Al(R₅)-O]_m-

Wherein, in chemical formula 2,

each R₅Are the same or different from each other and are each independently halogen; hydrocarbons having 1 to 20 carbon atoms;or a hydrocarbon having 1 to 20 carbon atoms substituted with halogen; and

m is an integer of 2 or more;

[ chemical formula 3]

J(R₆)₃

Wherein, in chemical formula 3,

each R₆Are the same or different from each other and are each independently halogen; hydrocarbons having 1 to 20 carbon atoms; or a hydrocarbon having 1 to 20 carbon atoms substituted with halogen; and

j is aluminum or boron;

[ chemical formula 4]

[E-H]⁺[ZA'₄]^-Or [ E]⁺[ZA'₄]^-

Wherein in the chemical formula 4, the first and second,

e is a neutral or cationic Lewis acid;

h is a hydrogen atom;

z is a group 13 element; and

each a' is the same as or different from each other, and is each independently an aryl group having 6 to 20 carbon atoms or an alkyl group having 1 to 20 carbon atoms, in which at least one hydrogen atom is unsubstituted or substituted with a halogen, a hydrocarbon having 1 to 20 carbon atoms, an alkoxy group or a phenoxy group.

5. The supported metallocene catalyst according to claim 1,

wherein the carrier is one or more selected from the group consisting of silica, alumina, magnesia and mixtures thereof.

6. The supported metallocene catalyst according to claim 1,

wherein the weight ratio of the transition metal of the metallocene compound to the support is 1:10 to 1: 1000.

7. A process for preparing polypropylene comprising the step of polymerizing propylene in the presence of the supported metallocene catalyst according to any one of claims 1 to 6.

8. The method for preparing polypropylene according to claim 7, wherein the polymerization of propylene is at a temperature of 25 to 500 ℃ and 1 to 100kgf/cm²Is carried out for 1 to 24 hours under pressure.

9. The process for preparing polypropylene according to claim 7, wherein hydrogen (H) is present at 30 to 2,000ppm based on propylene weight₂) The reaction is carried out in the presence of a catalyst.

Technical Field

Cross Reference to Related Applications

The present application claims priority from korean patent application No. 10-2017-.

The present invention relates to a novel supported metallocene catalyst and a method for preparing polypropylene using the same. According to the present invention, by using a supported catalyst containing a single metallocene compound, polypropylene having a relatively narrow molecular weight distribution and a SPAN value can be produced with high activity.

Background

Olefin polymerization catalyst systems can be classified into ziegler-natta catalysts and metallocene catalysts, and these high-activity catalyst systems have been developed according to their characteristics. Ziegler-natta catalysts have been widely used in commercial processes since the development of the fifties of the twentieth century. However, since the Ziegler-Natta catalyst is a multi-active site catalyst in which a plurality of active sites are mixed, it has a feature that the resulting polymer has a broad molecular weight distribution. In addition, since the composition distribution of the comonomer is not uniform, there is a problem that it is difficult to obtain desired physical properties.

Meanwhile, the metallocene catalyst includes a main catalyst having a transition metal compound as a main component and a cocatalyst having an organometallic compound having aluminum as a main component. Such catalysts are single site catalysts, which are homogeneous composite catalysts and, depending on the single site characteristics, provide polymers with narrow molecular weight distribution and uniform comonomer composition distribution. The tacticity, copolymerization characteristics, molecular weight, crystallinity, etc. of the resulting polymer can be controlled by varying the ligand structure of the catalyst and polymerization conditions.

U.S. Pat. No. 5,032,562 discloses a method for preparing a polymerization catalyst by supporting two different transition metal catalysts on one support. The catalyst is prepared by supporting a titanium (Ti) -based ziegler-natta catalyst producing a high molecular weight polymer and a zirconium (Zr) -based metallocene catalyst producing a low molecular weight polymer on one support, thereby producing a bimodal molecular weight distribution. The disadvantage of this process is that the loading step is complicated and the morphology of the polymer is poor due to the presence of the cocatalyst.

U.S. Pat. No. 5,525,678 discloses a process for the polymerization of olefins using a catalyst system in which a metallocene compound and a non-metallocene compound are simultaneously supported on a carrier to achieve simultaneous polymerization of a high molecular weight polymer and a low molecular weight polymer. However, there are disadvantages in that the metallocene compound and the non-metallocene compound must be separately supported, and the support must be pretreated with various compounds for supporting.

U.S. patent No. 5,914,289 discloses a method of controlling the molecular weight and molecular weight distribution of a polymer using metallocene catalysts, which are separately supported on a carrier. However, the preparation of the supported catalyst requires a large amount of solvent and a long time, and the process of supporting the metallocene catalyst on each support is troublesome.

Korean patent application No. 2003-12308 discloses a method of controlling the molecular weight distribution of a polymer, in which polymerization is performed by changing the combination of catalysts in a reactor by supporting a dinuclear metallocene catalyst and a mononuclear metallocene catalyst together with an activator on a support. However, this method has a limitation in simultaneously realizing the characteristics of the respective catalysts. In addition, there is a disadvantage in that the metallocene catalyst may be separated from the supported component of the resulting catalyst, resulting in fouling of the reactor.

Therefore, many studies have been made on metallocene catalysts for preparing polypropylene having narrow molecular weight distribution and SPAN value while having high activity in propylene polymerization, but the degree of research is still insufficient.

Disclosure of Invention

[ problem ] to provide a method for producing a semiconductor device

It is an object of the present invention to provide a supported metallocene catalyst comprising a novel metallocene compound capable of producing polypropylene having a relatively narrow molecular weight distribution and a SPAN value with high activity.

[ technical solution ] A

According to an embodiment of the present invention, there may be provided a supported metallocene catalyst comprising a metallocene compound represented by the following chemical formula 1 and a support.

[ chemical formula 1]

Wherein, in chemical formula 1,

n is an integer of 4 to 10,

R₁and R₂Are the same as or different from each other, and are each independently an aryl group having 6 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms substituted with an alkyl group having 1 to 20 carbon atoms;

R₃is an alkyl group having 1 to 20 carbon atoms.

R₄Is a tertiary amine having an alkyl group of 1 to 10 carbon atoms.

A is carbon, silicon or germanium; and

each X is the same or different from each other, and each is independently a halogen or an alkyl group having 1 to 20 carbon atoms.

For example, R in chemical formula 1₄Can be dimethylamine, dipropylamine, diisopropylamine, diphenylamine, methylpropylamine, methylaniline or isopropylaniline.

Also, the compound represented by chemical formula 1 may be one of the compounds represented by the following structural formulae.

In addition, the support may further include one or more promoter compounds selected from the group consisting of compounds represented by chemical formula 2, chemical formula 3, or chemical formula 4 below.

[ chemical formula 2]

-[Al(R₅)-O]_n-

Wherein, in chemical formula 2,

each R₅May be the same or different from each other, and each independently is halogen; hydrocarbons having 1 to 20 carbon atoms; or a hydrocarbon having 1 to 20 carbon atoms substituted with halogen; and

n is an integer of 2 or more.

[ chemical formula 3]

J(R₆)₃

Wherein, in chemical formula 3,

each R₆May be the same or different from each other, and each independently is halogen; hydrocarbons having 1 to 20 carbon atoms; or a hydrocarbon having 1 to 20 carbon atoms substituted with halogen; and

j is aluminum or boron;

[ chemical formula 4]

[E-H]⁺[ZA'₄]^-Or [ E]⁺[ZA'₄]^-

Wherein in the chemical formula 4, the first and second,

e is a neutral or cationic Lewis acid;

h is a hydrogen atom;

z is a group 13 element; and

each a' may be the same as or different from each other, and is each independently an aryl group having 6 to 20 carbon atoms or an alkyl group having 1 to 20 carbon atoms, in which at least one hydrogen atom is unsubstituted or substituted with a halogen, a hydrocarbon having 1 to 20 carbon atoms, an alkoxy group, or a phenoxy group.

And, the support may be one or more selected from the group consisting of silica, alumina, magnesia and a mixture thereof.

In this case, the weight ratio of the transition metal to the support contained in the metallocene compound may be about 1:10 to about 1: 1000.

Meanwhile, according to another embodiment of the present invention, there is provided a method for preparing polypropylene, which includes the step of polymerizing propylene in the presence of the above-mentioned supported metallocene catalyst.

The propylene can be polymerized by heating at a temperature of about 25 to about 500 ℃ and about 1 to about 100kgf/cm²Is carried out for about 1 to about 24 hours under pressure. At this time, it may be preferred to use hydrogen (H) at about 30 to about 2,000ppm based on the weight of propylene₂) The reaction is carried out in the presence of a catalyst.

[ PROBLEMS ] the present invention

The supported metallocene catalyst of the present invention can produce polypropylene having a relatively narrow molecular weight distribution and SPAN value with high activity.

Detailed Description

The terms "first," "second," and the like may be used herein to describe various elements and are used merely to distinguish one element from another.

Furthermore, the terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to be limiting of the invention. The singular is intended to include the plural unless the context clearly dictates otherwise. The terms "comprises," "comprising," or "having" are intended to specify the presence of stated features, integers, steps, elements, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, elements, or groups thereof.

While the invention is susceptible to various modifications and alternative forms, specific embodiments will be shown and described in detail below. It should be understood, however, that the description is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The present invention will be described in more detail below.

According to an embodiment of the present invention, there may be provided a supported metallocene catalyst comprising a metallocene compound represented by the following chemical formula 1 and a support.

[ chemical formula 1]

Wherein, in chemical formula 1,

n is an integer of 4 to 10,

R₁and R₂Are the same as or different from each other, and are each independently an aryl group having 6 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms substituted with an alkyl group having 1 to 20 carbon atoms;

R₃is an alkyl group having 1 to 20 carbon atoms;

R₄is a tertiary amine having an alkyl group of 1 to 10 carbon atoms.

A is carbon, silicon or germanium; and

x are the same or different from each other, and each independently is a halogen or an alkyl group having 1 to 20 carbon atoms.

For example, R in chemical formula 1₄Can be dimethylamine, dipropylamine, diisopropylamine, diphenylamine, methylpropylamine, methylaniline or isopropylaniline.

In addition, the compound represented by chemical formula 1 may be one of the compounds represented by the following structural formula:

generally, metallocene catalysts used for polypropylene polymerization undergo a supporting process in order to perform bulk polymerization, but the supporting process is troublesome and when the supporting does not proceed well, a process problem (fouling, etc.) occurs. In order to avoid the process problems, the existing metallocene catalysts have a problem of performing a prepolymerization process before main polymerization.

The present inventors have synthesized a novel catalyst on which a tether of a specific structure capable of causing a supporting reaction is incorporated, and confirmed that a catalyst compound can be effectively supported on a carrier due to such a tether, thereby completing the present invention.

In particular, the metallocene compound of the supported catalyst according to one embodiment of the present invention may have very large nucleophilicity by introducing an alkylene group of a certain length in the bridging group of the indenyl groups connected to each other, and then connecting a phenyl group having a relatively high electron density and a nitrogen-containing amino group.

Therefore, it can be more strongly bonded to the support than the conventional metallocene compound, and can have a relatively large number of single active sites than the conventional metallocene compound, and thus can exhibit uniform activity in propylene polymerization.

Thus, compared to conventional polypropylene, polypropylene prepared in the presence of the supported catalyst according to embodiments of the present invention may have uniform physical properties, e.g., having a relatively narrow molecular weight distribution and narrow SPAN value.

In chemical formula 1, n is an alkylene group for connecting a tether derived from a bridging group connecting indenyl groups, and is an integer of 4 to 10, preferably about 5 to 8, more preferably 6.

By maintaining the alkylene chain length as described above, the phenylene group and the amine group in the tether in the metallocene compound included in the supported catalyst of the present invention can be kept in electron delocalization, and thus the bonding between the metallocene compound and the support can be further enhanced, and the activity of the catalyst can be improved.

In addition, the supported metallocene catalyst according to an aspect of the present invention may exhibit high catalytic efficiency in propylene polymerization even without adding a separate cocatalyst due to the effect of activity improvement.

According to one embodiment of the present invention, the metallocene compound of chemical formula 1 may be obtained by linking an indene derivative with a bridge compound to prepare a ligand compound, and then adding a metal precursor compound thereto for metallization, without particular limitation.

More specifically, for example, the ligand compound is prepared by: the indene derivative is reacted with an organolithium compound such as n-butyllithium to produce a lithium salt, the halogenated compound of the bridge compound is mixed, and then the mixture is reacted. The reaction is performed for about 12 hours to about 24 hours by mixing the ligand compound or lithium salt thereof with the metal precursor compound until the reaction is completed, and then the reaction product is filtered and dried under reduced pressure to obtain the metallocene compound represented by chemical formula 1. The preparation method of the metallocene compound of chemical formula 1 will be described in detail below with reference to examples.

As the support in the supported metallocene catalyst according to one embodiment, a support containing a hydroxyl group or a siloxane group on the surface may be used. Specifically, the support may be a support containing a hydroxyl group or a siloxane group, which has high reactivity by drying at high temperature to remove moisture on the surface. More specifically, the support may be silica, alumina, magnesia or mixtures thereof. For example, the support may be one or more selected from silica, silica-alumina, and silica-magnesia. The support may be dried at elevated temperature. In general, the carrier may include oxide, carbonate, sulfate and nitrate components, such as Na₂O、K₂CO₃、BaSO₄And Mg (NO)₃)₂。

The amount of hydroxyl groups (-OH) on the surface of the carrier is preferably as small as possible, but it is practically difficult to eliminate all hydroxyl groups. The amount of the hydroxyl group can be controlled by the preparation method of the support, the preparation conditions, the drying conditions (temperature, time, drying method, etc.), etc., and the amount is preferably from 0.1mmol/g to 10mmol/g, more preferably from 0.1mmol/g to 1mmol/g, and further preferably from 0.1mmol/g to 0.5 mmol/g. In order to reduce side reactions caused by a small amount of hydroxyl groups remaining after drying, a carrier in which hydroxyl groups are chemically removed while highly reactive siloxane groups participating in the carrier remain may be used.

In addition, one or more compounds represented by chemical formula 2, chemical formula 3, or chemical formula 4 below may be additionally supported on the carrier as a co-catalyst.

[ chemical formula 2]

-[Al(R₅)-O]_m-

Wherein, in chemical formula 2,

each R₅May be the same as or different from each other, and each independently is a halogen, a hydrocarbon having 1 to 20 carbon atoms, or a hydrocarbon having 1 to 20 carbon atoms substituted with a halogen; and

m is an integer of 2 or more;

[ chemical formula 3]

J(R₆)₃

Wherein, in chemical formula 3,

each R₆May be the same as or different from each other, and each independently is a halogen, a hydrocarbon having 1 to 20 carbon atoms, or a hydrocarbon having 1 to 20 carbon atoms substituted with a halogen; and

j is aluminum or boron;

[ chemical formula 4]

[E-H]⁺[ZA'₄]^-Or [ E]⁺[ZA'₄]^-

Wherein in the chemical formula 4, the first and second,

e is a neutral or cationic Lewis acid;

h is a hydrogen atom;

z is a group 13 element; and

each a' may be the same as or different from each other, and is each independently an aryl group having 6 to 20 carbon atoms or an alkyl group having 1 to 20 carbon atoms, in which at least one hydrogen atom is unsubstituted or substituted with a halogen, a hydrocarbon having 1 to 20 carbon atoms, an alkoxy group, or a phenoxy group.

Non-limiting examples of the cocatalyst represented by chemical formula 2 include methylaluminoxane, ethylaluminoxane, isobutylaluminoxane, tert-butylaluminoxane, etc., and more preferred compounds include methylaluminoxane.

Examples of the compound represented by chemical formula 3 include trimethylaluminum, triethylaluminum, triisobutylaluminum, tripropylaluminum, tributylaluminum, dimethylaluminum chloride, triisopropylaluminum, tri-sec-butylaluminum, tricyclopentylaluminum, tripentylaluminum, triisopentylaluminum, trihexylaluminum, trioctylaluminum, ethyldimethylaluminum, methyldiethylaluminum, triphenylaluminum, tri-p-tolylaluminum, dimethylmethoxyaluminum, dimethylethoxyaluminum, trimethylboron, triethylboron, triisobutylboron, tripropylboron, tributylboron, etc., and more preferred compounds are selected from trimethylaluminum, triethylaluminum and triisobutylaluminum.

Examples of the compound represented by chemical formula 4 include triethylammonium tetraphenylborate, tributylammonium tetraphenylborate, trimethylammonium tetraphenylborate, tripropylammonium tetraphenylborate, trimethylammonium tetrakis (p-tolyl) borate, trimethylammonium tetrakis (o, p-dimethylphenyl) borate, tributylammonium tetrakis (p-trifluoromethylphenyl) borate, trimethylammonium tetrakis (p-trifluoromethylphenyl) borate, tributylammonium tetrapentafluorophenylborate, N-diethylanilinium tetraphenylborate, N-dimethylanilinium tetrapentafluorophenylborate, diethylammonium tetrapentafluorophenylborate, triphenylphosphonium tetraphenylborate, trimethylphosphonium tetraphenylborate, triethylammonium tetraphenylaluminum, tributylammonium tetraphenylaluminum, trimethylammonium tetraphenylaluminum, tripropylammonium tetraphenylaluminum, trimethylammonium tetrakis (p-methylphenyl) aluminum, Tripropylammonium tetrakis (p-methylphenyl) aluminum, triethylammonium tetrakis (o, p-dimethylphenyl) aluminum, tributylammonium tetrakis (p-trifluoromethylphenyl) aluminum, trimethylammonium tetrakis (p-trifluoromethylphenyl) aluminum, tributylammonium tetrapentafluorophenylaluminum, N-diethylanilinium tetraphenylaluminum, N-diethylanilinium tetrapentafluorophenylaluminum, diethylammonium tetrapentafluorophenylaluminum, triphenylphosphonium tetraphenylaluminum, trimethylphosphonium tetraphenylaluminum, tripropylammonium tetrakis (p-tolyl) borate, triethylammonium tetrakis (o, p-dimethylphenyl) borate, tributylammonium tetrakis (p-trifluoromethylphenyl) borate, triphenylcarbonium tetrapentafluorophenylborate, and the like.

Preferably, aluminoxane may be used as a cocatalyst, and more preferably, Methylaluminoxane (MAO) as alkylaluminoxane may be used. Further, the cocatalyst may be used in an appropriate amount so that activation of the metallocene compound as the catalyst precursor can be sufficiently performed.

The supported metallocene catalyst according to the present invention can be prepared by a first process comprising: 1) contacting the metallocene compound represented by chemical formula 1 with the compound represented by chemical formula 2 or chemical formula 3 to obtain a mixture, and 2) adding the compound represented by chemical formula 4 to the mixture.

Further, the supported metallocene catalyst according to the present invention may be prepared by a second method of contacting the metallocene compound represented by chemical formula 1 with the compound represented by chemical formula 2.

In the first method of preparing the supported catalyst, the molar ratio of the metallocene compound represented by chemical formula 1/the compound represented by chemical formula 2 or chemical formula 3 is preferably 1/5000 to 1/2, more preferably 1/1000 to 1/10, and most preferably 1/500 to 1/20. When the molar ratio of the metallocene compound represented by chemical formula 1/the compound represented by chemical formula 2 or chemical formula 3 exceeds 1/2, there is a problem in that the amount of the alkylating agent is very small and the metal compound cannot be completely alkylated. When the molar ratio is less than 1/5,000, the alkylation of the metal compound is completed, but there is a problem in that the alkylated metal compound cannot be completely activated due to a side reaction between the remaining excess alkylating agent and the activator of chemical formula 5. Further, the molar ratio of the metallocene compound represented by chemical formula 1/the compound represented by chemical formula 4 is preferably 1/25 to 1, more preferably 1/10 to 1, and most preferably 1/5 to 1. When the molar ratio of the metallocene compound represented by chemical formula 1/the compound represented by chemical formula 4 exceeds 1, there is a problem in that the activity of the prepared supported catalyst is deteriorated since the amount of the activator is relatively small and the metal compound is not completely activated. When the molar ratio is less than 1/25, the activation of the metal compound is completely completed, but there is a problem in that the cost of the supported catalyst is uneconomical or the purity of the polymer to be produced is lowered because an excessive amount of the activator remains.

In the second method of preparing the supported catalyst, the molar ratio of the metallocene compound represented by chemical formula 1/the compound represented by chemical formula 2 is preferably 1/10000 to 1/10, more preferably 1/5000 to 1/100, and most preferably 1/3000 to 1/500. When the molar ratio exceeds 1/10, there is a problem in that the activity of the prepared supported catalyst is deteriorated since the amount of the activator is relatively small and the metal compound is not completely activated. When the molar ratio is less than 1/10000, the activation of the metal compound is completely completed, but there is a problem in that the cost of the supported catalyst is uneconomical or the purity of the polymer to be produced is lowered due to the remaining excess amount of the activator.

As a reaction solvent used for preparing the supported catalyst, a hydrocarbon solvent such as pentane, hexane, heptane or the like, or an aromatic solvent such as benzene, toluene or the like can be used.

Further, when the metallocene compound and the cocatalyst compound are used in a form supported on the carrier, the content of the metallocene compound may be about 0.5 to about 20 parts by weight and the content of the cocatalyst may be about 1 to about 1000 parts by weight, based on 100 parts by weight of the carrier. Preferably, the metallocene compound may be contained in an amount of about 1 to about 15 parts by weight and the cocatalyst may be contained in an amount of about 10 to about 500 parts by weight, based on 100 parts by weight of the carrier. Most preferably, the metallocene compound may be contained in an amount of about 1 to about 100 parts by weight and the cocatalyst may be contained in an amount of about 40 to about 150 parts by weight, based on 100 parts by weight of the carrier.

In the supported metallocene catalyst of the present invention, the weight ratio of all transition metals contained in the metallocene compound to the support may be 1:10 to 1: 1000. When the support and the metallocene compound are contained in the above weight ratio, an optimum shape can be obtained. Further, the weight ratio of the cocatalyst compound to the support may be 1:1 to 1: 100. When the cocatalyst and the metallocene compound are contained in the above weight ratio, the activity and microstructure of the polymer can be optimized.

In addition to the above components, the supported metallocene catalyst may further comprise additives, auxiliaries and the like, which are generally used in the technical field of the present invention.

Meanwhile, according to another embodiment of the present invention, there is provided a method for preparing polypropylene, including the step of polymerizing propylene in the presence of a supported metallocene catalyst.

As described above, the supported metallocene catalyst can provide polypropylene having a narrow molecular weight distribution with high catalytic activity by using a catalyst of the metallocene compound of chemical formula 1 having an indene ligand of a specific substituent.

In the method of preparing polypropylene according to one embodiment of the present invention, the supported catalyst comprising the metallocene compound of chemical formula 1 has improved catalytic activity compared to a conventional ziegler-natta catalyst or a metallocene catalyst, and can prepare polypropylene with improved activity even if the supporting conditions of the metallocene compound, i.e., reaction temperature, reaction time, kind of silica, and supporting amount of the metallocene compound, are changed.

Here, the polymerization of the propylene monomer may be carried out at a temperature of about 25 ℃ to about 500 ℃ and about 1kgf/cm²To about 100kgf/cm²For about 1 to about 24 hours under pressure. At this time, the polymerization reaction temperature is preferably about 25 ℃ to about 200 ℃, and more preferably about 50 ℃ to about 100 ℃. Further, the polymerization pressure may be about 1 to about 70kgf/cm²And more preferably from about 5 to about 50kgf/cm². The polymerization time is preferably from about 1 to about 5 hours.

The preparation method of the polypropylene of the present invention may be performed by contacting propylene with a catalyst comprising a metallocene compound represented by chemical formula 1.

Further, according to an embodiment of the present invention, the polymerization of propylene may be performed in the presence of hydrogen.

At this time, hydrogen is used to activate the inert site of the metallocene catalyst by causing a chain transfer reaction and to control the molecular weight of the polymer. The metallocene compound of the present invention is excellent in hydrogen reactivity, and thus, by controlling the amount of hydrogen used in the polymerization process, polypropylene having a desired molecular weight level and melt index can be efficiently obtained.

The hydrogen used may be added in an amount of about 30 to about 2,000ppm, or about 50 to about 1,500ppm, or about 50 to about 500ppm, based on the total weight of the propylene. By controlling the amount of hydrogen used, the molecular weight distribution and Melt Index (MI) of the produced polypropylene can be controlled within a desired range showing sufficient catalytic activity, and thus polypropylene having appropriate properties according to the use can be produced. More specifically, since the metallocene catalyst of the present invention has very excellent hydrogen reactivity, it is possible to obtain polypropylene having a reduced molecular weight and a high melt index by activating the chain transfer reaction by increasing the amount of hydrogen used.

The preparation process of polypropylene can be carried out by a solution polymerization process, a slurry process or a gas phase process by using a continuous slurry polymerization reactor, a loop slurry reactor, a gas phase reactor, a solution reactor, etc.

In the preparation method of polypropylene according to the present invention, the catalyst may be dissolved or diluted in a C5-12 aliphatic hydrocarbon solvent such as pentane, hexane, heptane, nonane, decane and isomers thereof; aromatic hydrocarbon solvents such as toluene and benzene; and chlorinated hydrocarbon solvents such as methylene chloride and chlorobenzene are then injected into the reactor. Here, it is preferably used after removing a small amount of water or air as a catalytic poison by treatment with a small amount of aluminum alkyl.

In addition to the above steps, the preparation method of polypropylene may further comprise steps generally used in the technical field of the present invention.

Meanwhile, according to another embodiment of the present invention, there is provided polypropylene obtained by the preparation method.

As described above, according to the present invention, by using a catalyst comprising the novel metallocene compound, polypropylene having excellent processability and high polymerization activity without fouling can be obtained, compared to polymers prepared using existing metallocene compounds.

Polypropylene has a low processing temperature and is excellent in transparency and flowability, and therefore, it can be used for packaging containers, films, sheets, injection-molded parts, fiber products, and the like, which require such characteristics.

According to one embodiment of the present invention, when a polymerization process of propylene is performed by using a catalyst comprising a metallocene compound, the weight average molecular weight (Mw) of the produced polypropylene may depend on the amount of hydrogen introduced during the polymerization process, but it may be about 50,000 to about 1,000,000g/mol, or about 80,000 to about 500,000g/mol, preferably about 100,000 to about 300,000 g/mol.

In addition, the polypropylene produced according to the present invention can have a relatively narrow molecular weight distribution and SPAN value. For example, the polypropylene produced according to one embodiment of the present invention may have a molecular weight distribution value of about 3 or less, preferably about 2.6 or less, as measured by GPC, and a SPAN value of about 1 or less, preferably about 0.9 or less, more preferably about 0.7 to 0.8, as measured by an optical diffraction particle size analyzer. The SPAN value means the width of the particle size distribution, and polypropylene has a characteristic of small SPAN value and thus uniform particle size, which makes it possible to produce a product having high transparency, particularly less problematic in taste or odor peculiar to polypropylene.

In addition, due to the above characteristics, the polypropylene prepared according to an embodiment of the present invention may have very uniform characteristics, for example, it has a Melt Index (MI) of about 1 to about 10g/10min, preferably about 1 to 7g/10min, measured at 230 ℃ and under a load of 2.16 kg. In particular, since these physical properties can be easily adjusted according to the amount of hydrogen used during the polymerization process, polypropylene having appropriate molecular weight, molecular weight distribution and melting property can be produced according to the use.

Hereinafter, the action and effect of the present invention will be described in more detail with reference to specific examples. However, the following examples are provided for illustrative purposes only, and the present disclosure is not intended to be limited by these examples.

< example >

Preparation of metallocene compounds

Preparation example 1

Step 1-1: synthesis of 4- (6- (dichloro (methyl) silyl) hexyl) -N, N-dimethylaniline

In a flask, 4- (6-bromohexyl) -N, N-dimethylaniline (5.00g, 25mmol) and Mg (1.22g, 50.2mmol) were added to THF (25mL), and the mixture was stirred at 70 ℃ for 4 hours. In another flask, MeSiCl was added₃(7.47g, 50.0mmol) was dissolved in THF (75mL) and the mixture was slowly added dropwise at 0 deg.C for 1 hour. The mixture was then stirred at room temperature overnight, then saturated NaHCO was added₃. With anhydrous MgSO₄Water was removed, and the resulting solution was concentrated under reduced pressure to give 4- (6- (dichloro (methyl) silyl) hexyl) -N, N-dimethylaniline as a white solid (4.80g, 82%).

¹H NMR(500MHz,CDCl₃,7.24ppm):0.99(3H,s),3.01(6H,s),6.75(2H,d),7.57(2H,d)

Step 1-2: synthesis of 4- (6- (bis (4- (4- (tert-butyl) phenyl) -2-methyl-1H-inden-1-yl) (methyl) silyl) hexyl) -N, N-dimethylaniline

4- (4- (tert-butyl) phenyl) -2-methyl-1H-indene (10.3g, 39.3mmol) and CuCN (176mg, 1.97mmol) were dissolved under argon (Ar) in toluene (90mL) and THF (12 mL). The solution was cooled to-30 ℃ and n-butyllithium (2.5M in hexane, 16.5mL) was added slowly. After stirring for about 10 minutes at this temperature and raising the temperature to room temperature, the mixture was stirred for 2 hours. To the solution was added the resulting 4- (6- (dichloro (methyl) silyl) hexyl) -N, N-dimethylaniline (4.80g, 20.5mmol) in toluene (30mL), followed by stirring at room temperature overnight. After completion of the reaction, MTBE and water were added, and the organic layer was separated. The organic layer obtained was extracted with anhydrous MgSO₄Dried and concentrated to give 4- (6- (bis (4- (4- (tert-butyl) phenyl) -2-methyl-1H-inden-1-yl) (methyl) silyl) hexyl) -N, N-dimethylaniline (13.8g, 100%) as a white solid.

¹H NMR(500MHz,CDCl₃,7.24ppm):0.00-0.07(3H,m),1.49-1.52(18H,m),2.46-2.49(6H,m),3.00(3H,s),3.02(3H,s),4.23-4.39(2H,m),6.50-7.52(20H,m)

Step 1-3: synthesis of [4- (6- (bis (4- (4- (tert-butyl) phenyl) -2-methyl-1H-inden-1-yl) (methyl) silyl) hexyl) -N, N-dimethylanilinium ] dichloride

4- (6- (bis (4- (4- (tert-butyl) phenyl) -2-methyl-1H-inden-1-yl) (methyl) silyl) hexyl) -N, N-dimethylaniline (6.74g, 9.83mmol) was charged to a 50mL-Schlenk flask under argon (Ar) and dissolved by addition of diethyl ether (8.2 mL). The temperature was lowered to-78 ℃ and n-butyllithium (2.5M in hexane, 8.1mL) was added, followed by stirring at room temperature for 2 hours. ZrCl in a Tol/diethyl ether (24.6/8.2mL) slurry at-78 deg.C₄(2.29g, 9.83mmol) was added slowly to the ligand solution, the temperature was raised to room temperature and the mixture was stirred overnight. Distilling the solvent under reduced pressure to dissolve it in CH₂Cl₂And filtered to remove LiCl. The filtrate was concentrated and the resulting crude product was taken up with CH₂Cl₂Saturated, added twice the volume of hexane, and then recrystallized at-20 ℃ for 15 hours. Thereafter, when a yellow solid was formed, it was filtered, and then washed twice with hexane to obtain [4- (6- (bis (4- (4- (tert-butyl) phenyl) -2-methyl-1H-inden-1-yl) (methyl) silyl) hexyl) -N, N-dimethylaniline]Zirconium dichloride (225mg, 30%, r/m > 20/1).

¹H NMR(500MHz,CDCl₃,7.24ppm):1.30–1.40(21H,m),2.00(3H,s),2.33(3H,s),3.10(6H,s),6.85–7.94(18H,m)

Preparation of Supported catalysts