KR101265891B1 - Process for preparation of polyolefin having a broad molecular weight distribution - Google Patents

Abstract

The present invention is CGC represented by a specific formula; Cocatalyst represented by a specific chemical formula; And polymerizing an olefin monomer to obtain a polyolefin in the presence of a catalyst composition comprising a chain transfer agent, wherein the polyolefin prepared according to the present invention has a low molecular weight and has a broad molecular weight distribution. And a high melting point.

Accordingly, the polymer is processed more efficiently than the polymer having a narrow molecular weight distribution, and has good physical properties in injection molding or extrusion molding, and thus may be used for applications such as gaskets, wire and cable coatings, and the like.

Metallocenes, CGCs, promoters, chain transfer agents, molecular weight distribution, copolymers, polyolefins

Description

Process for preparation of polyolefin having a broad molecular weight distribution

The present invention relates to a polymerization method of a polyolefin using a metallocene catalyst, and more particularly, CGC represented by a specific chemical formula; Cocatalyst represented by a specific chemical formula; And a process for producing a polyolefin which polymerizes an olefin monomer in the presence of a catalyst composition comprising a chain transfer agent.

The most commonly encountered polymer in everyday life is by far polyolefin-based polymers. Given that the worldwide production of polyethylene (PE) and polypropylene (PP) reaches 70 million tonnes per year, polyolefins must be the polymer that has the greatest impact on our daily lives. Most of polyolefins are produced through low pressure processes using Ziegler-Natta catalysts and chromium-based catalysts, and some are produced from low density polyethylene using high pressure radical processes.

In the 1980s, research on olefin polymerization was revived as W. Kamonsky discovered ethylene polymerization with a metallocene catalyst, a homogeneous, single site catalyst system. In particular, the alpha-olefin polymerization technology using a metallocene catalyst has been much researched due to the fact that the so-called tailor-made polymer synthesis that can control the properties of the polymer by controlling the structure of the catalyst is possible. .

Various types having half-sandwich metallocene complexes having a bridge between cyclopentadienyl (Cp. C ₅ H ₅ ) groups, which are the core ligands of metallocene catalysts, and chelating ligands It has been found that the metal complex of is also characterized by a single activity point.

Metallocene catalysts can be classified by ligand, core metal and bridge bond. By changing the structure, it is possible to control the structure of the polymer produced by controlling the electronic and three-dimensional environment of the metallocene. That is, metallocene is capable of synthesizing various types of polymers and controlling physical properties of the resulting polymers by changing the types of ligands, substituents, bridge bonds and central metals.

Constrained geometry catalysts (CGCs) have been reported to be capable of copolymerizing ethylene, alpha-olefins, and styrene, and research is being conducted to investigate the correlation between CGC synthesis, polymerization characteristics and structures of various structures.

Dow announced [Me ₂ Si (Me ₄ C ₅ ) N t Bu] TiCl ₂ (Constrained-Geometry Catalyst, CGC) in the early 1990s (US Pat. No. 5,064,802), which copolymerizes ethylene and alpha-olefins. There are two major aspects of CGC's superiority to metallocene catalysts known to the prior art: (1) to produce high molecular weight polymers with high activity even at high polymerization temperatures, and (2 The copolymerization of alpha-olefins with high steric hindrances such as 1-hexene and 1-octene is also excellent. In addition, during the polymerization reaction, various characteristics of CGC are gradually known, and efforts to synthesize derivatives thereof and use them as polymerization catalysts have been actively conducted in academia and industry.

One approach has been to synthesize and polymerize metal compounds in which various other bridges and nitrogen substituents have been introduced instead of silicon bridges. Representative metal compounds known to date are listed as shown in [Figure 1] ( Chem. Rev. 2003, 103 , 283).

The compounds listed in Figure 1 above are phosphorus 1- (a), ethylene or propylene 1- (b), methylidene 1- (c), and methylene 1- (d) bridges instead of the CGC-structured silicon bridges. Although each is introduced, it did not give excellent results in terms of activity and copolymerization performance compared to the CGC of the silicon bridge in the ethylene polymerization or copolymerization with alpha-olefin.

In addition, as a different approach, many compounds composed of oxido ligands instead of the amido ligands of CGC have been synthesized, and some polymerization has been attempted. Examples are shown in [Figure 2].

In [Figure 2], 2- (a) is reported by TJ Marks et al. It is characterized by crosslinking of Cp derivative and oxido ligand by ortho-phenylene group ( Organometallics 1997, 16 , 5958). Compounds having the same crosslinks and polymerization using them have also been reported by Mu et al. ( Organometallics 2004, 23 , 540). In addition, it was reported by Rothwell et al. That an indenyl ligand and an oxido ligand were crosslinked by the same ortho-phenylene group ( Chem. Commun. 2003, 1034). 2- (b) reported by Whitby et al. Is characterized in that the cyclopentanienyl ligand and the oxido ligand were pierched by three carbons ( Organometallics 1999, 18 , 348). These catalysts are syndiotactic It has been reported to be active in syndiotactic polystyrene polymerization. Similar compounds have also been reported by Hessen et al. ( Organometallics 1998, 17 , 1652). The compound shown in 2- (c) is reported by Rau et al. And is characterized by showing activity in ethylene and ethylene / 1-hexene copolymerization at high temperature and pressure (210 ° C., 150 MPa) ( J. Organomet. Chem. 2000, 608 , 71). In addition, patent 2- (d) having a similar structure and high temperature and high pressure polymerization using the same have been patented by Sumitomo (US Patent 6,548,686).

Of all these attempts, however, only a few catalysts are actually used in commercial plants.

In addition, the metal atoms are the active sites of each individual CGC unit, and each of these units is a single metal atom so that these catalysts have a high molecular weight (e.g., greater than 10,000) with a narrow MWD (e.g., 2 or less) under a wide range of polymerization conditions. It is a tendency to produce the olefin polymer of the weight average molecular weight of the polymer) by a very efficient method. CGCs are ethylene homopolymers, copolymers of ethylene and one or more alpha-olefins (ie, olefins having 3 or more carbon atoms having ethylenic unsaturation between the first carbon and the second carbon), and interpolymers of ethylene, propylene, and diene monomers ( For example, EPDM terpolymers).

While narrow molecular weight distribution (MWD) can impart useful properties to ethylene-based polymers for certain applications, for example, film transparency, ethylene-based polymers with a wide molecular weight distribution (eg, greater than 2) It is generally processed more efficiently than ethylene-based polymers of narrow molecular weight distribution and has better physical properties, for example temperature performance suitable for applications such as injection molded or extruded articles (eg gaskets, wire and cable coatings). Several processes are known for producing a wide range of molecular weight ethylene-based polymers or polymer blends using CGC, but all processes require improvement.

The present invention is to solve the problems of the prior art as described above, to provide a method for producing a polyolefin polymer having a low density, high melting point while having a wide molecular weight distribution in the presence of a metallocene catalyst.

The present invention is a means for solving the above problems, CGC represented by the following formula (1); A promoter represented by the following Chemical Formulas 2 to 4; And polymerizing the olefin monomer in the presence of a catalyst composition comprising a chain transfer agent to obtain a polyolefin.

[Formula 2]

R ₅ is a halogen group, a hydrocarbyl group having 1 to 20 carbon atoms, or a halogen substituted hydrocarbyl group having 1 to 20 carbon atoms, which may be the same as or different from each other in a repeating unit, and a is an integer of 2 or more.

J is aluminum or boron, R ₅ is a halogen group, a hydrocarbyl group having 1 to 20 carbon atoms or a halogen-substituted hydrocarbyl group having 1 to 20 carbon atoms, three may be the same or different.

In the above formula, L is a neutral or cationic Lewis acid, H is a hydrogen atom, Z is a Group 13 element, and each of A is independently one or more hydrogen is a halogen, a hydrocarbyl group having 1 to 20 carbon atoms, an alkoxy group Or an aryl or alkali group having 6 to 20 carbon atoms substituted with a phenoxy group.

The present invention provides another polyolefin prepared by the production method according to the present invention as another means for solving the above problems.

The polyolefin preferably has an average molecular weight distribution of 10 to 14, a density of 0.89 to 0.91, and preferably a melting point (T _m ) of 110 to 125 ° C.

Polyolefins prepared according to the invention include CGCs represented by certain formulas; Cocatalyst represented by a specific chemical formula; And polymerized in the presence of a catalyst composition comprising a chain transfer agent, having a broad molecular weight distribution, having a low density and a high melting point. Accordingly, the polymer is processed more efficiently than the polymer having a narrow molecular weight distribution, and has good physical properties in injection molding or extrusion molding, and thus may be used for applications such as gaskets, wire and cable coatings, and the like.

The present invention is a CGC (constrained geometry catalyst) represented by the formula (1); A promoter represented by the following Chemical Formulas 2 to 4; And polymerizing an olefin monomer in the presence of a catalyst composition comprising a chain transfer agent to obtain a polyolefin.

[Formula 2]

R ₅ is a halogen group, a hydrocarbyl group having 1 to 20 carbon atoms, or a halogen substituted hydrocarbyl group having 1 to 20 carbon atoms, which may be the same as or different from each other in a repeating unit, and a is an integer of 2 or more.

(3)

J (R ₅ ) ₃

J is aluminum or boron, R ₅ is a halogen group, a hydrocarbyl group having 1 to 20 carbon atoms or a halogen-substituted hydrocarbyl group having 1 to 20 carbon atoms, three may be the same or different.

[Formula 4]

[LH] ⁺ [ZA ₄ ] ^- or [L] ⁺ [ZA ₄ ] ^-

In the above formula, L is a neutral or cationic Lewis acid, H is a hydrogen atom, Z is a Group 13 element, and each of A is independently one or more hydrogen is a halogen, a hydrocarbyl group having 1 to 20 carbon atoms, an alkoxy group Or an aryl or alkali group having 6 to 20 carbon atoms substituted with a phenoxy group.

Preparation of the polyolefin according to the present invention is CGC represented by the formula (1); A promoter represented by the following Chemical Formulas 2 to 4; And it is characterized in that it is carried out in the presence of a catalyst composition comprising a chain transfer agent, the components of the catalyst composition will be described in more detail below.

The catalyst composition includes a constrained geometry catalyst (CGC) represented by Chemical Formula 1 as a main catalyst.

In general, the simplest way to synthesize metallocene complexes is to deprotonate Cp ligands (cyclopentadienyl: C ₅ H ₅ ) to produce metal salts (Li, Na, K, Ti, Mg, MgCl, etc.), React with MCl ₄ , ZrCl ₄ (THF) ₂ or TiCl ₃ (THF) ₃ .

CGC represented by Chemical Formula 1 may be substituted with NaC ₅ H ₅ and an excess of SiMe ₂ Cl ₂ to obtain (C ₅ H ₅ ) SiMe ₂ Cl, and then substituted with t-BuNH ₂ to substitute (C ₅ H ₅ ) SiMe ₂ (N (H) -t-Bu) can be obtained and finally prepared by reacting with TiCl ₄ .

The catalyst composition includes a cocatalyst represented by the following Chemical Formulas 2 to 4 together with CGC (constrained geometry catalyst) represented by the following Chemical Formula 1 as a main catalyst.

[Formula 2]

R ₅ is a halogen group, a hydrocarbyl group having 1 to 20 carbon atoms, or a halogen substituted hydrocarbyl group having 1 to 20 carbon atoms, which may be the same as or different from each other in a repeating unit, and a is an integer of 2 or more.

The promoter represented by Chemical Formula 2 may be, for example, methylalumoxane (MAO).

(3)

J (R ₅ ) ₃

J is aluminum or boron, R ₅ is a halogen group, a hydrocarbyl group having 1 to 20 carbon atoms or a halogen-substituted hydrocarbyl group having 1 to 20 carbon atoms, three may be the same or different.

[Formula 4]

[LH] ⁺ [ZA ₄ ] ^- or [L] ⁺ [ZA ₄ ] ^-

In the above formula, L is a neutral or cationic Lewis acid, H is a hydrogen atom, Z is a Group 13 element, and each of A is independently one or more hydrogen is a halogen, a hydrocarbyl group having 1 to 20 carbon atoms, an alkoxy group Or an aryl or alkali group having 6 to 20 carbon atoms substituted with a phenoxy group.

More specifically, the cocatalyst represented by Chemical Formula 4 may be trimethylammonium tetrakis (pentafluorophenyl) borate, triethylammonium tetrakis (pentafluorophenyl) borate, tripropylammonium tetrakis (pentafluorophenyl) borate , And trityl tetrakis (pentafluorophenyl) borate It is preferable that it is one or more boron compounds chosen from the group which consists of etc., and it is more preferable that it is trityl tetrakis (pentafluorophenyl) borate.

It is preferable that it is 1-20 molar ratio with respect to CGC, and, as for the content of the said promoter, it is more preferable that it is 5-10 molar ratio. If the content is less than 1 molar ratio, there is a fear that the catalytic activity is lowered, and if it exceeds 20 molar ratio, there is a concern that a low molecular weight polyolefin is obtained.

The catalyst composition comprises a chain transfer agent together with the main catalyst and the promoter. Chain Transfer Agents lead to the termination of polymer chain growth and deliver the growth polymer at once as a transfer agent.

The chain transfer agent is preferably a Group 1, 2, 12 or 13 metal compound containing a linear or branched alkyl group having 1 to 20 carbon atoms. It is preferably an aluminum, gallium, or zinc compound substituted with an alkyl group having 1 to 12 carbon atoms, more preferably a trialkyl aluminum or dialkyl zinc compound substituted with an alkyl group having 2 to 8 carbon atoms, triethylaluminum, tri (i Most preferred is -propyl) aluminum, tri (i-butyl) aluminum, tri (n-hexyl) aluminum, tri (n-octyl) aluminum, triethylgallium, or diethylzinc.

The content of the chain transfer agent is preferably 10 to 50 molar ratio, more preferably 15 to 30 molar ratio with respect to CGC. If the content is less than 10 molar ratios, there is a fear that it has a narrow molecular weight distribution, if it exceeds 50 molar ratios there is a fear that the catalytic activity is lowered.

The olefin monomer polymerized in the presence of the catalyst composition preferably comprises ethylene as the first monomer and olefin other than ethylene as the second monomer.

The ethylene may be introduced into the reactor at 1 to 10 bar during the polymerization.

The second monomer is a comonomer, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-octene, 1 Straight or branched chain alpha-olefins having 4 to 20 carbon atoms, such as -decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene or 1-eicosene; Cyclopentene, cycloheptene, norbornene, 5-methyl-2-norbornene, tetracyclododecene or 2-methyl-1,4,5,8-dimethano-1,2,3,4,4a Cycloolefins having 3 to 20 carbon atoms such as 5,8,8a-octahydronaphthalene; Butadiene, isoprene, 4-methyl-1,3-pentadiene, 1,3-pentadiene, 1,4-pentadiene, 1,5-hexadiene, 1,4-hexadiene, 1,3-hexadiene, 1,3-octadiene, 1,4-octadiene, 1,5-octadiene, 1,6-octadiene, 1,7-octadiene, ethylidene norbornene, vinyl norbornene, dicyclopentadiene , Polyene-olefins such as 7-methyl-1,6-octadiene, 4-ethylidene-8-methyl-1,7-nonadiene or 5,9-dimethyl-1,4,8-decatene In the present invention, it may include one or more comonomers selected from the group consisting of them.

The second monomer is preferably included in an amount of 0.1 to 2 molar concentration. If the content is less than 0.1 molar concentration, there is a fear of obtaining a polymer having a high density, and if the content exceeds 2 molar concentration, there is a fear of obtaining a polymer having a low density and a low melting point.

For reference, the molarity of the second monomer is the number of moles of the second monomer with respect to 1 L of the solvent in which the second monomer is dissolved.

In addition, the polymerization reaction of the olefin monomer in the presence of the catalyst composition proceeds in the same manner as the polymerization method of olefin using a conventional metallocene catalyst.

The solvent that can be used for the polymerization reaction is not particularly limited in the case of a solvent that can be used for polyolefin polymerization, and may be toluene, hexane, or the like as a specific example.

In particular, the polymerization reaction of the olefin monomer of the present invention is preferably carried out substantially in the absence of oxygen and water.

More specifically, the polymerization is preferably carried out at 60 to 110 ℃, it is preferably carried out at 1 to 10 pressure (bar).

The present invention also

It relates to a polyolefin produced by the method for producing a polyolefin according to the present invention. The polyolefin produced by the method for producing a polyolefin according to the present invention is characterized by having a low molecular weight and a high melting point while having a wide molecular weight distribution. Accordingly, the polymer is processed more efficiently than the polymer having a narrow molecular weight distribution, and has good physical properties in injection molding or extrusion molding, and thus may be used for applications such as gaskets, wire and cable coatings, and the like.

More specifically, the polyolefin according to the present invention preferably has an average molecular weight distribution of 10 to 14. In addition, the density of the polyolefin is preferably 0.89 to 0.91 (g / cm ³ ), the melting point (T _m ) is preferably 110 to 125 ℃.

Example 1 Ethylene, 1-Octene Copolymerization

100 ml of toluene and 4.05 ml of 1-octene are added to a 500 ml Andrews Glass reactor and the reactor is preheated to 90 ° C. Using a syringe, CGC (5 μmol), trityl tetrakis (pentafluorophenyl) borate (25 μmol) cocatalyst represented by the following Chemical Formula 1, and diethyl zinc (125 μmol) are sequentially filled. At this time, ethylene pressure (3 bar) was added, the copolymerization reaction was carried out for 10 minutes, the remaining ethylene was removed, and the polymer solution was precipitated by adding excess methanol. The obtained polymer is dried in a vacuum oven at 60 ° C. for at least 24 hours.

Example 2

The polymer was prepared in the same manner as in Example 1 to confirm reproducibility.

Comparative Example: Ethylene, 1-Octene Copolymerization

100 ml of toluene and 4.05 ml of 1-octene are added to a 500 ml Andrews Glass reactor and the reactor is preheated to 90 ° C. Using a syringe, CGC (5 μmol) represented by Chemical Formula 1 and trityl tetrakis (pentafluorophenyl) borate cocatalyst (25 μmol) are sequentially filled. At this time, ethylene pressure (3 bar) was added, the copolymerization reaction was carried out for 10 minutes, the remaining ethylene was removed, and the polymer solution was precipitated by adding excess methanol. The obtained polymer is dried in a vacuum oven at 60 ° C. for at least 24 hours.

division Temperature
(℃) Ethylene
(bar) catalyst
(μmol) Co-catalyst
(μmol) Comonomer
(ml) CTA
(μmol) Example 1 90 3 5 25 4.05 125 Example 2 90 3 5 25 4.05 125 Comparative example 90 3 5 25 4.05 0 CTA: Chain Transfer Agent

[ Test Example]

The polymers prepared in Examples and Comparative Examples were evaluated in the following manners, and the results are shown in Table 2 below.

1.Polydispersity index (PDI)

The number average molecular weight (Mn) and the weight average molecular weight (Mw) were measured by gel permeation chromatography (GPC: Gel Permeation Chromatography), and the weight average molecular weight was calculated by dividing the number average molecular weight.

2. Melting Point (T _m )

After the temperature was increased to 200 ° C., it was kept at that temperature for 5 minutes, then lowered to 30 ° C., and the temperature was further increased to make the top of the DSC (Differential Scanning Calorimeter, TA) curve as the melting point. At this time, the rate of temperature rise and fall is 10 ° C./min, and a melting point is obtained while the second temperature is rising.

3. Density

Samples treated with antioxidants (1,000 ppm) were prepared in a press mold at 180 ° C., 3 mm thick, 2 cm in diameter, cooled to 10 ° C./min and measured on a Mettler balance.

division Yield (g) Density (g / cm ³ ) T _m (℃) Mw PDI Example 1 8.92 0.891 113.5 69235 12.5 Example 2 8.90 0.892 122.5 79919 11.2 Comparative example 10.58 0.911 91.5 129920 2.2

Referring to Table 2, the ethylene and 1-octene copolymers prepared in Examples 1 and 2 have a smaller yield than the copolymers prepared in Comparative Example, but have a low molecular weight and a high melting point while having a wide molecular weight distribution. .

1 is a thermal analysis result of a polymer prepared according to Example 2 measured by differential scanning calorimeter (DSC).

2 shows the molecular weight distribution of the polymer prepared according to Example 2. FIG.

Claims (14)

Constrained Geometry Catalyst (CGC) represented by Formula 1; A promoter represented by the following Chemical Formula 2, 3, or 4; And in the presence of a catalyst composition comprising a dialkyl zinc compound substituted with an alkyl group having 2 to 8 carbon atoms, A method for producing a polyolefin comprising polymerizing an olefin monomer to obtain a polyolefin:

[Formula 2]

(The R ₅ is a halogen group, a hydrocarbyl group having 1 to 20 carbon atoms or a halogen-substituted hydrocarbyl group having 1 to 20 carbon atoms, which may be the same as or different from each other in the repeating unit, and a is an integer of 2 or more). (3) J (R ₅ ) ₃ (The J is aluminum or boron, R ₅ is a halogen group, a hydrocarbyl group having 1 to 20 carbon atoms or a halogen-substituted hydrocarbyl group having 1 to 20 carbon atoms, three may be the same or different) [Formula 4] [LH] ⁺ [ZA ₄ ] ^- or [L] ⁺ [ZA ₄ ] ^- (Wherein L is a neutral or cationic Lewis acid, H is a hydrogen atom, Z is a Group 13 element, and each of A is independently one or more hydrogens are halogen, a hydrocarbyl group having 1 to 20 carbon atoms, alkoxy) Aryl or an alkali group having 6 to 20 carbon atoms substituted with a group or a phenoxy group) The method of claim 1, Cocatalyst represented by the formula (4) is trimethylammonium tetrakis (pentafluorophenyl) borate, triethylammonium tetrakis (pentafluorophenyl) borate, tripropylammonium tetrakis (pentafluorophenyl) borate and trityl tetra A method for producing a polyolefin, characterized in that at least one boron compound selected from the group consisting of kiss (pentafluorophenyl) borate. The method of claim 1, The content of the promoter is a method for producing a polyolefin, characterized in that 1 to 20 molar ratio with respect to the CGC. delete The method of claim 1, The dialkyl zinc compound substituted with an alkyl group having 2 to 8 carbon atoms is diethyl zinc. The method of claim 1, The content of the dialkyl zinc compound substituted with an alkyl group having 2 to 8 carbon atoms is 10 to 50 molar ratio with respect to the CGC. The method of claim 1, The olefin monomer may comprise at least one comonomer selected from the group consisting of ethylene as the first monomer and linear or branched alpha-olefins having 4 to 20 carbon atoms, cycloolefins having 3 to 20 carbon atoms and polyene-olefins as the second monomer. Method for producing a polyolefin, characterized in that it comprises a. The method of claim 7, wherein The ethylene is a method for producing a polyolefin, characterized in that the input to the reactor at 1 to 10 bar. delete The method of claim 7, wherein The content of the second monomer is a method for producing a polyolefin, characterized in that 0.1 to 2 molar concentration. A polyolefin prepared by the process according to any one of claims 1 to 3, 5 to 8 or 10. The method of claim 11, Polyolefin has an average molecular weight distribution of 10 to 14 polyolefin. The method of claim 11, The polyolefin has a density of 0.89 to 0.91 g / cm ³ polyolefin. In claim 11, The polyolefin has a melting point (T _m ) of 110 to 125 ℃ polyolefin.

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