KR20230072858A - Method for preparing polypropylene copolymer - Google Patents

Abstract

The present invention provides a catalyst suitable for preparing a high molecular weight polypropylene copolymer and a method for preparing a polypropylene copolymer using the same.
The polypropylene copolymer prepared according to the present invention has a high molecular weight and a low melt index.

Description

Polypropylene copolymer manufacturing method {METHOD FOR PREPARING POLYPROPYLENE COPOLYMER}

The present invention relates to a method for preparing a polypropylene copolymer.

In the process of polymerizing or copolymerizing olefin monomers to produce polyolefins, various catalyst compounds are used to achieve higher reaction efficiency and to obtain polymers having desired physical properties. Catalysts used in such polyolefin polymerization can be classified into a Ziegler-Natta catalyst system and a metallocene catalyst system, and these two highly active catalyst systems have been developed according to their respective characteristics.

A Ziegler-Natta catalyst system is generally composed of a titanium or vanadium compound main catalyst component and an alkylaluminum compound cocatalyst component. However, the Ziegler-Natta catalyst system is a multi-active point catalyst in which several active species are mixed, and is characterized by a wide molecular weight distribution of the polymer, but there is a limit to securing desired physical properties because the composition distribution of the comonomer is not uniform.

In addition, since the metallocene catalyst system composed of metallocene compounds of transition metals of group 4 of the periodic table such as titanium, zirconium, and hafnium and methylaluminoxane as a cocatalyst is a homogeneous catalyst with a single catalytic active site, it is Compared to the Ziegler-Natta catalyst system, the molecular weight distribution of the polymer is narrow, the composition distribution of the comonomer is uniform, and the properties of the polymer can be changed according to the ligand structure modification of the catalyst.

In addition, since the metallocene catalyst has better reactivity to comonomers than the conventional Ziegler-Natta catalyst system, a polymer having a high comonomer content can be obtained with high activity even with a small amount of comonomer. Even if the same amount of comonomer is used, it is possible to make a high molecular weight polymer with a more uniform composition distribution, so that it can be used as a film or elastic body with good physical properties. In addition, since low molecular weight waxy extracts are hardly generated inside the copolymer, it can be applied to applications requiring hygiene such as medical use.

During propylene polymerization, a bisindenyl-based metallocene catalyst with a C ₂ symmetry structure is generally used and exhibits a high isotactability (identity index) of 95% or more. However, when preparing the catalyst, a rac structure having iso-selectivity and a meso structure having no stereoregularity are generated at the same time, so there is a disadvantage in that the rac and meso structures must be separated. Unlike the C ₂ symmetric structure, metallocene catalysts with a C ₁ symmetric structure do not simultaneously form rac and meso structures during catalyst production, which can increase catalyst production efficiency. However, copolymerization with ethylene improves copolymerizability, but it is difficult to prepare a polypropylene copolymer having a high isotacticity and a high molecular weight compared to a C ₂ symmetrical structure (US Patent No. 9266910).

Organometallics 2006, 25, 1217-1229

An object of the present invention is to provide a catalyst suitable for preparing a high molecular weight polypropylene copolymer and a method for preparing a polypropylene copolymer using the same.

One aspect of the present invention is a method for producing a polypropylene copolymer comprising the step of polymerizing propylene and at least one C ₄ -C ₂₀ α-olefin comonomer in the presence of a catalyst comprising a transition metal compound represented by Formula 1 below provides:

[Formula 1]

(In Formula 1,

M is a Group 4 transition metal;

Q ¹ and Q ² are each independently a halogen, a (C ₁ -C ₂₀ )alkyl group, a (C ₂ -C ₂₀ )alkenyl group, a (C ₂ -C ₂₀ )alkynyl group, a (C ₆ -C ₂₀ )aryl group, (C ₁ -C ₂₀ ) Alkyl (C ₆ -C ₂₀ ) Aryl group, (C ₆ -C ₂₀ ) Aryl (C ₁ -C ₂₀ ) Alkyl group, (C ₁ -C ₂₀ ) Alkylamido group, (C ₆ - C ₂₀ ) arylamido group or (C ₁ -C ₂₀ ) alkylidene group;

A is a Group 14 element;

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ and R ¹² are independently substituted or unsubstituted with hydrogen, an acetal group or an ether group (C ₁ -C ₂₀ ) Alkyl group, acetal group or ether group substituted or unsubstituted (C ₂ -C ₂₀ ) Alkenyl group, acetal group or ether group substituted or unsubstituted (C ₁ -C ₂₀ ) Alkyl (C ₆ -C ₂₀ )Aryl group, acetal group or ether group substituted or unsubstituted (C ₆ -C ₂₀ )aryl (C ₁ -C ₂₀ )alkyl group, or acetal group or ether group substituted or unsubstituted (C ₁ - C ₂₀ ) A silyl group, and two or more groups of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , and R ⁷ may combine with each other to form an aliphatic ring or an aromatic ring, and R ⁸ , Two or more groups of R ⁹ , R ¹⁰ , R ¹¹ and R ¹² may combine with each other to form an aliphatic ring or an aromatic ring).

A is carbon (C), silicon (Si), or germanium (Ge), and R ² and R ³ may each independently be hydrogen or an acetal group or an ether group-substituted or unsubstituted (C ₁ -C ₂₀ )alkyl group. there is.

The R ⁸ and R ⁹ may combine with each other to form an aromatic ring.

The transition metal compound represented by Chemical Formula 1 may include a naphthyl group.

The catalyst may further include a cocatalyst compound selected from the group consisting of compounds represented by Formulas 2 to 4 below:

[Formula 2]

-[Al(Ra)-O] _n -

(In Formula 2 above,

Ra are each independently halogen; Or a halogen-substituted or unsubstituted (C ₁ -C ₂₀ )hydrocarbyl group,

n is an integer greater than or equal to 2),

[Formula 3]

Q(Rb) ₃

(In Formula 3,

Q is aluminum or boron;

Rb is each independently halogen; or a halogen-substituted or unsubstituted (C ₁ -C ₂₀ )hydrocarbyl group);

[Formula 4]

[W] ⁺ [Z(Rc) ₄ ] ^-

(In Chemical Formula 4,

[W] ⁺ is a cationic Lewis acid; or a cationic Lewis acid to which a hydrogen atom is bonded;

Z is a group 13 element,

Rc is each independently a (C ₁ -C ₂₀ ) aryl group substituted with one or two or more substituents selected from the group consisting of a halogen, a (C ₁ -C ₂₀ ) hydrocarbyl group, an alkoxy group, and a phenoxy group; It is a (C ₁ -C ₂₀ )alkyl group substituted with one or two or more substituents selected from the group consisting of a halogen, a (C ₁ -C ₂₀ )hydrocarbyl group, an alkoxy group, and a phenoxy group).

The comonomer may be 1-butene.

Another aspect of the present invention provides a polypropylene copolymer prepared according to the above production method and having a comonomer unit content of 5 to 50% by weight based on the total weight of the polypropylene copolymer.

Another aspect of the present invention is prepared according to the above production method, and provides a polypropylene copolymer having a melt index (MI) of 0.1 to 8.

According to the present invention, a high molecular weight polypropylene copolymer having a high comonomer unit content can be prepared by applying a specific catalyst.

In addition, the polypropylene copolymer prepared according to the present invention has a low melt index.

Hereinafter, preferred embodiments of the present invention will be described. However, the embodiments of the present invention can be modified in various forms, and the scope of the present invention is not limited to the embodiments described below.

As used herein, the term "alkyl" refers to a monovalent straight-chain or branched saturated hydrocarbon radical composed of only carbon and hydrogen atoms. Examples of such alkyl radicals include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t- butyl, pentyl, hexyl, octyl, dodecyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, and the like.

In addition, the term "alkenyl" described in the present invention refers to a straight-chain or branched-chain hydrocarbon radical containing at least one carbon-carbon double bond, and includes ethenyl, propenyl, butenyl, pentenyl, and the like, It is not limited to this.

In addition, the term "alkynyl" described in the present invention refers to a straight-chain or branched-chain hydrocarbon radical containing at least one carbon-carbon triple bond, and includes methynyl, ethynyl, propynyl, butynyl, pentynyl, and hexy. but is not limited to yl, heptynyl, octynyl, and the like.

In addition, the term "aryl" described in the present invention is an organic radical derived from an aromatic hydrocarbon by removing one hydrogen, and includes single or fused ring systems. Specific examples include, but are not limited to, phenyl, naphthyl, biphenyl, anthryl, fluorenyl, phenanthryl, triphenylenyl, pyrenyl, perylenyl, chrysenyl, naphthacenyl, fluoranthenyl, and the like.

In addition, the term "alkylaryl" described in the present invention means an organic group in which one or more hydrogens of an aryl group are substituted with an alkyl group, and includes methylphenyl, ethylphenyl, n-propylphenyl, isopropylphenyl, n-butylphenyl, iso butylphenyl, t-butylphenyl, and the like, but are not limited thereto.

In addition, the term "arylalkyl" described in the present invention refers to an organic group in which one or more hydrogens of an alkyl group are substituted by an aryl group, and includes, but is not limited to, phenylpropyl, phenylhexyl, and the like.

In addition, the term "amido" described in the present invention means an amino group (-NH ₂ ) bonded to a carbonyl group (C=O), and "alkylamido" means that at least one hydrogen in -NH ₂ of the amido group is an alkyl group It means an organic group substituted with, and "arylamido" means an organic group in which at least one hydrogen in -NH ₂ of an amido group is substituted with an aryl group, and the alkyl group in the alkylamido group and the aryl group in the arylamido group are It may be the same as the examples of the above-described alkyl group and aryl group, but is not limited thereto.

In addition, the term "alkylidene" described in the present invention refers to a divalent aliphatic hydrocarbon group in which two hydrogen atoms are removed from the same carbon atom of the alkyl group, and includes ethylidene, propylidene, isopropylidene, butylidene, and pentylidene. and the like, but are not limited thereto.

In addition, the term "acetal" described in the present invention refers to an organic group formed by a bond between an alcohol and an aldehyde, that is, a substituent having two ether (-OR) bonds on one carbon, and includes methoxymethoxy, 1-methyl Toxyethoxy, 1-methoxypropyloxy, 1-methoxybutyloxy, 1-ethoxyethoxy, 1-ethoxypropyloxy, 1-ethoxybutyloxy, 1-(n-butoxy)ethoxy, 1-(iso-butoxy)ethoxy, 1-(sec-butoxy)ethoxy, 1-(tert-butoxy)ethoxy, 1-(cyclohexyloxy)ethoxy, 1-methoxy -1-methylmethoxy, 1-methoxy-1-methylethoxy, etc., but are not limited thereto

In addition, the term "ether" described in the present invention is an organic group having at least one ether linkage (-O-), and includes 2-methoxyethyl, 2-ethoxyethyl, 2-butoxyethyl, and 2-phenoxyethyl. , 2-(2-methoxyethoxy)ethyl, 3-methoxypropyl, 3-butoxypropyl, 3-phenoxypropyl, 2-methoxy-1-methylethyl, 2-methoxy-2-methylethyl , 2-methoxyethyl, 2-ethoxyethyl, 2-butoxyethyl, 2-phenoxyethyl, and the like, but are not limited thereto.

In addition, the term "silyl" described in the present invention refers to a -SiH ₃ radical derived from silane, and at least one of hydrogen atoms in the silyl group may be substituted with various organic groups such as alkyl and halogen. as trimethylsilyl, triethylsilyl, t-butyldimethylsilyl, vinyldimethylsilyl, propyldimethylsilyl, triphenylsilyl, diphenylsilyl, phenylsilyl, trimethoxysilyl, methyldimeroxysilyl, ethyldiethoxysilyl, triethoxysilyl, vinyldimethoxysilyl, triphenoxysilyl, and the like.

In addition, the term "alkoxy" described in the present invention refers to an -O-alkyl radical, where 'alkyl' is as defined above. Examples of such alkoxy radicals include, but are not limited to, methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, t-butoxy, and the like.

In addition, the term “halogen” described in the present invention means a fluorine, chlorine, bromine or iodine atom.

In addition, the term “C _n ” described in the present invention means that the number of carbon atoms is n.

The present invention provides a method for preparing a polypropylene copolymer comprising polymerizing propylene and at least one C ₄ -C ₂₀ α-olefin comonomer in the presence of a specific catalyst. Polypropylene copolymers prepared according to the present invention are of high molecular weight and thus have low melt index.

In the present invention, the catalyst may include a transition metal compound represented by Formula 1 below.

[Formula 1]

In Formula 1, M is a Group 4 transition metal, and preferably may be titanium (Ti), zirconium (Zr), or hafnium (Hf).

In addition, Q ¹ and Q ² are each independently a halogen, a (C ₁ -C ₂₀ )alkyl group, a (C ₂ -C ₂₀ )alkenyl group, a (C ₂ -C ₂₀ )alkynyl group, and a (C ₆ -C ₂₀ )aryl group. group, (C ₁ -C ₂₀ )alkyl(C ₆ -C ₂₀ )aryl group, (C ₆ -C ₂₀ )aryl(C ₁ -C ₂₀ )alkyl group, (C ₁ -C ₂₀ )alkylamido group, (C ₆ -C ₂₀ )Arylamido group or (C ₁ -C ₂₀ )alkylidene group, preferably a halogen or (C ₁ -C ₂₀ )alkyl group, more preferably a chloro group or a methyl group.

In addition, A is a Group 14 element, preferably carbon (C), silicon (Si) or germanium (Ge), more preferably silicon (Si).

In addition, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ and R ¹² are each independently substituted with hydrogen, an acetal group or an ether group, or Unsubstituted (C ₁ -C ₂₀ )alkyl group, acetal group or ether group substituted or unsubstituted (C ₂ -C ₂₀ )alkenyl group, acetal group or ether group substituted or unsubstituted (C ₁ -C ₂₀ )alkyl (C ₆ -C ₂₀ ) substituted or unsubstituted with an aryl group, acetal group or ether group (C ₆ -C ₂₀ ) aryl (C ₁ -C ₂₀ ) alkyl group, or substituted or unsubstituted with an acetal group or ether group (C ₁ -C ₂₀ ) A silyl group, and two or more groups of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , and R ⁷ may combine with each other to form an aliphatic ring or an aromatic ring, and R Two or more groups of ⁸ , R ⁹ , R ¹⁰ , R ¹¹ and R ¹² may combine with each other to form an aliphatic ring or an aromatic ring.

Preferably, R ² and R ³ may each independently be a hydrogen or an acetal group or an ether group-substituted or unsubstituted (C ₁ -C ₂₀ )alkyl group.

Also, preferably, R ⁸ and R ⁹ may be bonded to each other to form an aromatic ring, whereby the transition metal compound represented by Chemical Formula 1 may include a naphthyl group.

In the present invention, the catalyst may include a cocatalyst compound. The cocatalyst compound activates the catalyst compound, and an aluminoxane compound, an organo-aluminum compound, or a bulky compound that activates the catalyst compound may be used. Specifically, the cocatalyst compound may be selected from the group consisting of compounds represented by Chemical Formulas 2 to 4 below.

[Formula 2]

-[Al(Ra)-O] _n -

(In Formula 2 above,

Ra are each independently halogen; Or a halogen-substituted or unsubstituted (C ₁ -C ₂₀ )hydrocarbyl group,

n is an integer greater than or equal to 2),

[Formula 3]

Q(Rb) ₃

(In Formula 3,

Q is aluminum or boron;

Rb is each independently halogen; or a halogen-substituted or unsubstituted (C ₁ -C ₂₀ )hydrocarbyl group);

[Formula 4]

[W] ⁺ [Z(Rc) ₄ ] ^-

(In Chemical Formula 4,

[W] ⁺ is a cationic Lewis acid; or a cationic Lewis acid to which a hydrogen atom is bonded;

Z is a group 13 element,

Rc is each independently a (C ₁ -C ₂₀ ) aryl group substituted with one or two or more substituents selected from the group consisting of a halogen, a (C ₁ -C ₂₀ ) hydrocarbyl group, an alkoxy group, and a phenoxy group; It is a (C ₁ -C ₂₀ )alkyl group substituted with one or two or more substituents selected from the group consisting of a halogen, a (C ₁ -C ₂₀ )hydrocarbyl group, an alkoxy group, and a phenoxy group).

The cocatalyst compound is included in the catalyst together with the metallocene compound represented by Chemical Formula 1 to activate the metallocene compound. Specifically, in order for the metallocene compound to become an active catalyst component used in olefin polymerization, a ligand in the metallocene compound is extracted to cationize the central metal (M ¹ or M ² ) while counter ion having weak binding force, That is, the compound including the unit represented by Chemical Formula 2, the compound represented by Chemical Formula 3, and the compound represented by Chemical Formula 4 that can act as an anion act together as cocatalysts.

The 'unit' represented by Formula 2 is a structure in which n structures in [ ] are connected in a compound, and other structures in the compound are not particularly limited as long as they include the unit represented by Formula 2, and repetition of Formula 2 It may be a cluster type, for example, a spherical compound, in which units are linked to each other.

In order for the cocatalyst compound to exhibit a better activation effect, the compound represented by Formula 2 is not particularly limited as long as it is an alkylaluminoxane, but preferred examples are methylaluminoxane, ethylaluminoxane, isobutylaluminoxane, and butylaluminoxane. oxane and the like, and a particularly preferred compound is methylaluminoxane.

In addition, the compound represented by Formula 3 is not particularly limited as an alkyl metal compound, and non-limiting examples thereof include trimethyl aluminum, triethyl aluminum, triisobutyl aluminum, tripropyl aluminum, tributyl aluminum, dimethylchloro aluminum, triiso Propyl aluminum, tri-s-butyl aluminum, tricyclopentyl aluminum, tripentyl aluminum, triisopentyl aluminum, trihexyl aluminum, trioctyl aluminum, ethyldimethyl aluminum, methyl diethyl aluminum, triphenyl aluminum, tri-p-tolyl Aluminum, dimethyl aluminum methoxide, dimethyl aluminum ethoxide, trimethyl boron, triethyl boron, triisobutyl boron, tripropyl boron, tributyl boron and the like. Considering the activity of the metallocene compound, one or two or more selected from the group consisting of trimethylaluminum, triethylaluminum and triisobutylaluminum may be preferably used.

Considering the activity of the metallocene compound, the compound represented by Formula 4 is a dimethylanilinium cation when [W] ⁺ is a cationic Lewis acid bonded to a hydrogen atom, and [W] ⁺ is a cationic Lewis acid. [(C ₆ H ₅ ) ₃ C] ⁺ , and [Z(Rc) ₄ ] ^- is [B(C ₆ F ₅ ) ₄ ] ^- .

The compound represented by Formula 4 is not particularly limited, but non-limiting examples when [W] ⁺ is a hydrogen atom bonded cationic Lewis acid include triphenylcarbenium borate, trimethylammonium tetraphenylborate, and methyldioctadecylammonium tetraphenyl. Borate, triethylammonium tetraphenylborate, tripropylammonium tetraphenylborate, tri(n-butyl)ammonium tetraphenylborate, methyltetradecylooctadecylammonium tetraphenylborate, N,N-dimethylaninium tetraphenylborate, N ,N-diethylaninium tetraphenylborate, N,N-dimethyl(2,4,6-trimethylaninium)tetraphenylborate, trimethylammonium tetrakis(pentafluorophenyl)borate, methylditetradecylammonium tetrakis (pentaphenyl) borate, methyldioctadecylammonium tetrakis (pentafluorophenyl) borate, triethylammonium tetrakis (pentafluorophenyl) borate, tripropylammonium tetrakis (pentafluorophenyl) borate, tri(n -Butyl) ammonium tetrakis (pentafluorophenyl) borate, tri (sec-butyl) ammonium tetrakis (pentafluorophenyl) borate, N, N-dimethylaninium tetrakis (pentafluorophenyl) borate, N , N-diethylaninium tetrakis (pentafluorophenyl) borate, N, N-dimethyl (2,4,6-trimethylaninium) tetrakis (pentafluorophenyl) borate, trimethylammonium tetrakis (2, 3,4,6-tetrafluorophenyl)borate, triethylammonium tetrakis(2,3,4,6-tetrafluorophenyl)borate, tripropylammonium tetrakis(2,3,4,6-tetrafluoro Rophenyl)borate, tri(n-butyl)ammonium tetrakis(2,3,4,6-tetrafluorophenyl)borate, dimethyl(t-butyl)ammonium tetrakis(2,3,4,6-tetrafluoro Lophenyl) borate, N, N-dimethylaninium tetrakis (2,3,4,6-tetrafluorophenyl) borate, N, N-diethylaninium tetrakis (2,3,4,6-tetra Fluorophenyl)borate, N,N-dimethyl-(2,4,6-trimethylaninium)tetrakis-(2,3,4,6-tetrafluorophenyl)borate, dioctadecylammonium tetrakis(penta Fluorophenyl) borate, ditetradecylammonium tetrakis (pentafluorophenyl) borate, dicyclohexylammonium tetrakis (pentafluorophenyl) borate, triphenylphosphonium tetrakis (pentafluorophenyl) borate, methyl di Octadecylphosphonium tetrakis(pentafluorophenyl)borate, tri(2,6-dimethylphenyl)phosphonium tetrakis(pentafluorophenyl)borate, methyldi(octadecyl)ammonium tetrakis(pentafluorophenyl) borate, methyldi(tetradecyl)-ammonium tetrakis(pentafluorophenyl)borate, triethyltetrakis(pentafluorophenyl)borate and the like.

A catalyst can be prepared using the compounds of Formulas 1 to 4, and the method exemplified below can be used as a method for preparing the catalyst.

First, when Q ¹ and Q ² of the transition metal compound represented by Formula 1 are halogen, there is a method of contacting the compound represented by Formula 2. Second, when Q ¹ and Q ² in Formula 1 are alkyl radicals, a catalyst may be prepared by contacting a mixture of a transition metal compound and a compound represented by Formulas 3 and 4, or a compound represented by Formulas 3 and 4 It is also prepared by directly introducing each of the polymerizers.

The addition amount of the cocatalyst compound may be determined in consideration of the addition amount of the transition metal compound represented by Formula 1 and the amount required to sufficiently activate the transition metal compound. The content of the cocatalyst compound may be 1:1 to 100,000 based on the molar ratio of the metal contained in the cocatalyst compound with respect to 1 mol of the transition metal contained in the transition metal compound represented by Formula 1, and preferably 1: It may be 1 to 10,000, more preferably 1:1 to 5,000.

More specifically, in the case of the first method, the compound represented by Formula 2 is preferably 1:10 to 5,000 molar ratio, more preferably 1:50 to 1,000 molar ratio, with respect to the transition metal compound represented by Formula 1, Preferably, it may be included in a molar ratio of 1:100 to 1,000. When the molar ratio of the compound represented by Formula 2 to the transition metal compound of Formula 1 is less than 1:10, the amount of aluminoxane is very small, and activation of the transition metal compound may not be completely performed. If it exceeds, the excess aluminoxane may act as a catalyst poison and the polymer chain may not grow well.

In the case of the second method, when A of the cocatalyst compound represented by Formula 3 is boron, 1:1 to 100, preferably 1:1 to 10, more preferably 1:1 to 10 with respect to the transition metal compound represented by Formula 1 Preferably, it may be included in a molar ratio of 1:1 to 3. In addition, when A of the cocatalyst compound represented by Formula 3 is aluminum, it may vary depending on the amount of water in the polymerization system, but with respect to the transition metal compound represented by Formula 1, 1:1 to 1000, preferably 1: It may be included in a molar ratio of 1 to 500, more preferably 1:1 to 100.

In addition, the cocatalyst compound represented by Formula 4 may be included in a molar ratio of 1:0.5 to 30, preferably 1:0.7 to 20, and more preferably 1:1 to 10 with respect to the transition metal compound represented by Formula 1. . When the ratio of the cocatalyst compound represented by Formula 4 is less than 1:0.5, the amount of the activator is relatively small, so that the metal compound cannot be fully activated, resulting in a problem in that the activity of the resulting catalyst composition is reduced. If it exceeds 30, the metal compound is completely activated, but the unit price of the catalyst composition may be uneconomical or the purity of the resulting polymer may be low due to the remaining excess activator.

The catalyst according to the present invention can be used without separate support, and can also be used alone for preparing a polypropylene copolymer without mixing with other catalysts.

On the other hand, in the present invention, the copolymer produced through a polymerization process carried out by directly contacting propylene and at least one C ₄ -C ₂₀ α-olefin comonomer compound has a relatively insoluble and/or fixed catalyst site, resulting in a polymer chain According to these information, it can be prepared by polymerization of monomers under rapidly immobilizing conditions. Such immobilization can be effected, for example, by using a solid insoluble catalyst, carrying out the polymerization in a medium in which the resulting polymer is generally insoluble, and maintaining the polymerization reactants and products below the crystallization temperature (T _c ) of the polymer. .

The aforementioned catalyst is preferably applicable to the copolymerization of propylene and 1-butene. Hereinafter, a method for preparing a polypropylene copolymer comprising polymerizing propylene and at least one C ₄ -C ₂₀ α-olefin comonomer in the presence of the catalyst will be described.

Propylene polymerization processes are well known in the art and include bulk polymerization, solution polymerization, slurry polymerization and low pressure gas phase polymerization. Metallocene catalysts are particularly useful in known types of operation using fixed bed, moving bed or slurry processes carried out in single, series or parallel reactors.

When the polymerization reaction is carried out in a liquid or slurry phase, a solvent or propylene or ethylene monomer itself may be used as a medium.

Since the catalyst presented in the present invention exists in a homogeneous form in a polymerization reactor, it is preferable to apply it to a solution polymerization process carried out at a temperature equal to or higher than the melting point of the corresponding polymer. However, as disclosed in U.S. Patent No. 4,752,597, a non-uniform catalyst composition obtained by supporting the transition metal catalyst and cocatalyst on a porous metal oxide support may be used in a slurry polymerization or gas phase polymerization process. Therefore, when the catalyst of the present invention is used together with an inorganic carrier or an organic polymer carrier, it can be applied to a slurry or gas phase process. That is, the transition metal compound and the cocatalyst compound may be used in a form supported on an inorganic carrier or an organic polymer carrier.

The solvent usable during the polymerization reaction may be an aliphatic hydrocarbon-based solvent, an aromatic hydrocarbon-based solvent, a halogenated aliphatic hydrocarbon-based solvent, or a mixture thereof. Here, the aliphatic hydrocarbon-based solvent is a non-limiting example, butane, isobutane, pentane, hexane, heptane, octane, nonane, decane (decane), undecane, dodecane, cyclopentane, methylcyclopentane, cyclohexane, and the like. In addition, the aromatic hydrocarbon solvent is a non-limiting example, benzene, monochlorobenzene, dichlorobenzene, trichlorobenzene, toluene, xylene, chlorobenzene (Chlorobenzene) and the like. In addition, the halogenated aliphatic hydrocarbon solvent is a non-limiting example, dichloromethane, trichloromethane, chloroethane, dichloroethane, trichloroethane, 1,2-dichloroethane (1,2-Dichloroethane) and the like.

In the present invention, the polypropylene copolymer may be prepared by polymerizing propylene and C ₄ -C ₂₀ α-olefin comonomers, particularly propylene and 1-butene, in the presence of the above catalyst. In this case, the transition metal compound and the cocatalyst component may be separately introduced into the reactor or mixed in advance and introduced into the reactor, and mixing conditions such as the order of addition, temperature, or concentration are not particularly limited. For example, when preparing a copolymer of propylene and 1-butene, 1-butene may be included in an amount of 0.1 to 99.9% by weight, preferably 1 to 75% by weight, more preferably 5 to 50% by weight can be included as

Meanwhile, in the polymerization reaction according to the present invention, the addition amount of the catalyst may be determined within a range in which the polymerization reaction of monomers can sufficiently occur according to a slurry phase, liquid phase, gas phase or solution process, and is not particularly limited. However, the addition amount of the catalyst is preferably 10 ^-8 to 1 mol / L based on the concentration of the central metal (M) in the transition metal compound per unit volume (L) of the monomer, and 10 ^-7 to 10 ^-1 mol /L is more preferable, and it is still more preferable that it is 10 ^-7 to 10 ^-2 mol/L.

In addition, the polymerization reaction of the present invention may be performed in a batch type, semi-continuous type or continuous type reaction, preferably in a continuous type reaction.

The temperature and pressure conditions of the polymerization reaction of the present invention may be determined in consideration of the efficiency of the polymerization reaction depending on the type of reaction and reactor to be applied, but the polymerization temperature is 40 to 150 ° C, preferably 60 to 100 ° C It may be, and the pressure may be 1 to 100 atm, preferably 5 to 50 atm.

The polypropylene copolymer prepared according to the present invention may increase polymerization activity of monomers and exhibit high molecular weight by using a catalyst including a transition metal compound and a cocatalyst compound.

At this time, the polypropylene copolymer may have a melt index (MI) of 0.001 to 100, preferably 0.01 to 50, more preferably 0.1 to 30, and most preferably 0.1 to 8. In addition, the comonomer unit content of the polypropylene copolymer may be 0.1 to 99.9% by weight, preferably 1 to 75% by weight, and more preferably 5 to 50% by weight.

Example

Hereinafter, embodiments of the present invention will be described in detail. The following examples are only for understanding of the present invention, but do not limit the present invention.

Example

(1) Ligand preparation

2-Methyl-4-naphthyl-indene was synthesized according to Non-Patent Document 1. In a 250 mL flask containing 50 mL of hexane, 2-methyl-4-naphthyl-indene (2.56 g, 10 mmol) was added and dissolved, and 4.4 mL of n-butyllithium (n-BuLi) (2.5 mL in hexane) was dissolved at 0 ° C. M solution) was slowly added dropwise to the flask above. After stirring for 1 hour, stirring was performed at room temperature for 12 hours, and after the reaction was completed, hexane was filtered and the obtained powder was dried. After dissolving this powder in 50 mL of THF, 1.2 mL (10 mmol) of dichlorodimethylsilane was slowly added dropwise at -78 °C. After stirring for 1 hour, the mixture was stirred for 12 hours at room temperature. After completion of the reaction, the reaction mixture was dried under vacuum for 6 hours. After dissolving the obtained red liquid in 10 mL of THF, it was slowly added dropwise to a THF solution containing Li-tetramethyl cyclopentadienide in a slurry state at -78°C. After stirring for 1 hour, the mixture was stirred for 12 hours at room temperature. After the reaction was completed, the solution was washed with diethyl ether/water, and the obtained organic layer was dehydrated with magnesium sulfate (MgSO ₄ ), and the solvent was removed to prepare a ligand.

(2) Catalyst preparation

1.3 g (3 mmol) of the ligand prepared above was put into a 100 mL flask, dissolved in 30 mL of diethyl ether, and then 2.6 mL of n-butyllithium (n-BuLi) (2.5 M solution in hexane) was slowly added dropwise at 0 ° C. . After stirring for 1 hour, the mixture was reacted for 12 hours, and 0.2 g (3 mmol) of zirconium chloride (IV) (ZrCl ₄ ) was slowly added dropwise at -78°C. After stirring for 1 hour, the mixture was reacted at room temperature for 12 hours. After the reaction was completed, the reaction mixture was separated by filtration and drying, and recrystallized with toluene to obtain dimethylsilyl 2-methyl-4-naphthyl-indenyl 2,3,4,5-tetramethyl cyclopenta represented by the following formula (5) A dienyl zirconium dichloride (dimethylsilyl 2-methyl-4-naphthyl-indenyl 2,3,4,5-tetramethyl cyclopentadienyl zirconium dichloride) catalyst was prepared.

[Formula 5]

(3) Preparation of propylene-butene copolymer

1 L of anhydrous hexane and 190 g of 1-butene were injected into a 2 L stainless steel autoclave reactor completely purged with nitrogen, and 2 mL of triisobutylaluminum (1 M solution in hexane) was injected into the reactor. did Propylene was injected so that the reactor pressure was 10 bar, and then the temperature was raised to 70 °C. 1.5 μmol of the prepared catalyst compound was dissolved in 5 ml of anhydrous hexane and injected into the reactor, and MAO was injected into the reactor as a cocatalyst. Thereafter, polymerization was performed at 70° C. for 30 minutes. After completion of the polymerization, the reactor was cooled to room temperature, excess propylene was removed through a discharge line, and vacuum drying was performed at 80° C. for 15 hours or more to prepare a propylene-butene copolymer.

Comparative Example 1

Dimethylsilyl 2-methyl-4-(4-tert-butyl-phenyl)-indenyl 2,3,4,5-tetramethyl cyclopentadienyl zirconium dichloride (dimethylsilyl 2-methyl-4-(4-tert- A propylene-butene copolymer was prepared in the same manner as in Example using a butyl-phenyl)-indenyl 2,3,4,5-tetramethyl cyclopentadienyl zirconium dichloride) catalyst.

Comparative Example 2

Same as Example except that polymerization was carried out at 90 ° C. using a dimethylsilyl bis (2-methyl-4-phenyl-indenyl) zirconium dichloride catalyst. A propylene-butene copolymer was prepared by the method.

Property evaluation

(1) Melting point (Tm)

Using TA's Q-200 Differential Scanning Calorimetry (DSC), it was measured by raising the temperature at 10 °C/min within the range of 25 °C to 200 °C in 3 steps.

(2) Density

It was measured based on ASTM D1505.

(3) Melting Index (MI)

Measured based on ASTM D1238.

in the copolymer
1-butene unit content
[weight%] Melting point (Tm) [°C] density
[g/mL] Melt index (MI)
[g/10min]]
(2.16 kg @ 190℃) Example 31.4 84.9 0.885 4.1 Comparative Example 1 32.7 84.5 0.885 11.3 Comparative Example 2 29.9 89.2 0.888 9.3

The propylene-butene copolymers of Examples prepared under the catalyst according to the present invention showed a low melt index with a high content of 1-butene units, whereas the propylene-butene copolymers of Comparative Examples 1 and 2 had a higher melting point than those of Examples. It was confirmed that the index was indicated.

Claims (8)

A method for producing a polypropylene copolymer comprising polymerizing propylene and at least one C ₄ -C ₂₀ α-olefin comonomer in the presence of a catalyst comprising a transition metal compound represented by Formula 1 below:
[Formula 1]

(In Formula 1,
M is a Group 4 transition metal;
Q ¹ and Q ² are each independently a halogen, a (C ₁ -C ₂₀ )alkyl group, a (C ₂ -C ₂₀ )alkenyl group, a (C ₂ -C ₂₀ )alkynyl group, a (C ₆ -C ₂₀ )aryl group, (C ₁ -C ₂₀ ) Alkyl (C ₆ -C ₂₀ ) Aryl group, (C ₆ -C ₂₀ ) Aryl (C ₁ -C ₂₀ ) Alkyl group, (C ₁ -C ₂₀ ) Alkylamido group, (C ₆ - C ₂₀ ) arylamido group or (C ₁ -C ₂₀ ) alkylidene group;
A is a Group 14 element;
R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ and R ¹² are independently substituted or unsubstituted with hydrogen, an acetal group or an ether group (C ₁ -C ₂₀ ) Alkyl group, acetal group or ether group substituted or unsubstituted (C ₂ -C ₂₀ ) Alkenyl group, acetal group or ether group substituted or unsubstituted (C ₁ -C ₂₀ ) Alkyl (C ₆ -C ₂₀ )Aryl group, acetal group or ether group substituted or unsubstituted (C ₆ -C ₂₀ )aryl (C ₁ -C ₂₀ )alkyl group, or acetal group or ether group substituted or unsubstituted (C ₁ - C ₂₀ ) A silyl group, and two or more groups of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , and R ⁷ may combine with each other to form an aliphatic ring or an aromatic ring, and R ⁸ , Two or more groups of R ⁹ , R ¹⁰ , R ¹¹ and R ¹² may combine with each other to form an aliphatic ring or an aromatic ring).
According to claim 1,
A is carbon (C), silicon (Si) or germanium (Ge),
R ² and R ³ are each independently hydrogen or an acetal group or an ether group substituted or unsubstituted (C ₁ -C ₂₀ ) characterized in that the alkyl group, polypropylene copolymer production method.
According to claim 1,
R ⁸ and R ⁹ are characterized in that bonded to each other to form an aromatic ring, polypropylene copolymer production method.
According to claim 1,
The transition metal compound represented by Formula 1 is characterized in that it comprises a naphthyl group, polypropylene copolymer production method.
According to claim 1,
The catalyst further comprises a cocatalyst compound selected from the group consisting of compounds represented by Formulas 2 to 4 below, polypropylene copolymer production method.
[Formula 2]
-[Al(Ra)-O] _n -
(In Formula 2 above,
Ra are each independently halogen; Or a halogen-substituted or unsubstituted (C ₁ -C ₂₀ )hydrocarbyl group,
n is an integer greater than or equal to 2),

[Formula 3]
Q(Rb) ₃
(In Formula 3,
Q is aluminum or boron;
Rb is each independently halogen; or a halogen-substituted or unsubstituted (C ₁ -C ₂₀ )hydrocarbyl group);

[Formula 4]
[W] ⁺ [Z(Rc) ₄ ] ^-
(In Chemical Formula 4,
[W] ⁺ is a cationic Lewis acid; or a cationic Lewis acid to which a hydrogen atom is bonded;
Z is a group 13 element,
Rc is each independently a (C ₁ -C ₂₀ ) aryl group substituted with one or two or more substituents selected from the group consisting of a halogen, a (C ₁ -C ₂₀ ) hydrocarbyl group, an alkoxy group, and a phenoxy group; It is a (C ₁ -C ₂₀ )alkyl group substituted with one or two or more substituents selected from the group consisting of a halogen, a (C ₁ -C ₂₀ )hydrocarbyl group, an alkoxy group, and a phenoxy group).
According to claim 1,
The method for producing a polypropylene copolymer, characterized in that the comonomer is 1-butene.
A polypropylene copolymer prepared according to any one of claims 1 to 6, wherein the comonomer unit content is 5 to 50% by weight based on the total weight of the polypropylene copolymer.
A polypropylene copolymer prepared according to any one of claims 1 to 6 and having a melt index (MI) of 0.1 to 8.