KR20110078715A - Ziegler-natta catalyst for olefin polymerization and process for preparing it - Google Patents

Abstract

PURPOSE: A method for preparing a Ziegler-Natta catalyst for olefin polymerization is provided to ensure high activity and to easily produce an olefin polymer with high melt flow index by improving the reactivity of hydrogen as a molecular weight control agent. CONSTITUTION: A method for preparing a Ziegler-Natta catalyst for olefin polymerization comprises: (i) preparing a magnesium supporter; (ii) dipping a transition metal compound to the supporter; and (iii) adding an inner electron donor. The inner electron donor is 2-pyrrolidinone having a structure of chemical formula 2 and derivatives thereof. In chemical formula 2, R is hydrogen or C1~C20 linear, branched, and annular alkyl, alkenyl, cycloalkyl, aryl or aryl substituents, alkylaryl or alkylaryl substituents, and alkylaryl including heteroatom.

Description

Ziegler-Natta catalyst for olefin polymerization and process for preparing it

The present invention relates to a method for preparing a Ziegler-Natta catalyst, and more particularly, to preparing a Ziegler-Natta catalyst, the internal electron donor is characterized by comprising 2-pyrrolidinone and a derivative thereof. The present invention relates to a Ziegler-Natta catalyst for easily producing an isotactic propylene polymer having improved melt flowability by improving the reactivity of hydrogen as a molecular weight regulator.

The catalyst for olefin polymerization, generally called a Ziegler-Natta catalyst, refers to a catalyst system composed of a combination of a main catalyst composed mainly of a transition metal compound, a cocatalyst of an organometallic compound, and an electron donor, and has conventionally improved polymerization activity and stereoregularity. It has been extensively studied in the direction of reducing the fine powder content of the polymer and many related technologies have been proposed.

The Ziegler-Natta catalyst directly affects the properties and properties of the polyolefin produced according to its constituents, structure, and preparation method. Therefore, in order to change the properties of the resulting polyolefin, the catalyst should be accompanied by a change in the composition of the catalyst, a change in the structure of the carrier and a change in the preparation method of the catalyst. In addition, studies on the activity of the catalyst and the molecular weight, stereoregularity, and hydrogen reactivity of the polymerized polymer should be carried out simultaneously.

Conventional Ziegler-Natta catalysts consist of a solid catalyst component centered on titanium, magnesium and halogen compounds and an organoaluminum compound system that is a promoter. Although many improvements have been made to improve the catalytic activity and stereoregularity which are the basic elements in this system, due to the diversified use of polyolefins, it is currently required to have catalytic activity, stereoregularity and high hydrogen reactivity.

In order to solve the stereoregularity problem, U.S. Patent No. 4,544,717 describes a method of adding an electron donor, and U.S. Patent No. 4,226,741 relates to a high stereoregularity catalyst having a stereoregularity of 94 to 95 or more. It is described. EP 045,977 also describes the technology of solid Ziegler-Natta catalysts which are characterized by high activity, high stereoregularity, and derivatives of certain carboxylic acid ester compounds, preferably phthalate derivatives, are solid catalysts as internal electron donors. Coordination to the compound produces a Ziegler-Natta catalyst with the titanium compound. In addition, these main catalysts have been proposed to improve the polymerization activity and stereoregularity by alpha-olefin polymerization using an aluminum alkyl compound and a silicon compound having at least one silicon-ether bond as an external electron donor. However, when the catalyst disclosed by the above patents is used, it is practically difficult to produce polypropylene having a melt flow index of 50 g / 10 minutes or more because of insufficient reactivity of hydrogen as a molecular weight regulator.

In other words, if a large amount of hydrogen is added to the polymerization reactor to compensate for insufficient hydrogen reactivity when applied to the actual commercial process, there is a risk of explosion due to the limitation of the device design pressure. Constraints exist. Therefore, in the actual commercial process, there is a problem in that hydrogen can not be added to the pressure required to produce a polypropylene having a high melt flowability.

The present invention is to solve the problems of the prior art as described above, the object of the present invention, in the process of preparing a Ziegler-Natta catalyst for olefin polymerization, through the method of using a specific compound as an internal electron donor, In addition to being high enough for commercial use, the reactivity of hydrogen, the molecular weight regulator, is improved to provide a method for easily preparing an olefin polymer having a much higher melt flow index even when the same amount of hydrogen is introduced into the reactor. The purpose is.

Method for producing a Ziegler-Natta catalyst for olefin polymerization according to the present invention comprises the steps of preparing a magnesium carrier (a), supporting a transition metal compound on the carrier (b), adding an internal electron donor (c) It includes, the internal electron donor used in the method for preparing the Ziegler-Natta catalyst for olefin polymerization is characterized in that 2-pyrrolidinone (2-Pyrrolidinone) having a structure of formula (2) and its derivatives.

Ziegler-Natta catalyst for olefin polymerization according to the present invention is prepared by the method described above, 0.5 to 15% by weight of transition metal, 5 to 40% by weight of magnesium, 40 to 80% by weight of halogen and internal electron donor 2.5 based on the total weight of the catalyst. Characterized in that it comprises ~ 30% by weight.

The Ziegler-Natta catalyst for olefin polymerization according to the present invention not only has high activity for commercial use, but also improves the reactivity of hydrogen, a molecular weight regulator, so that even when the same amount of hydrogen is introduced into the reactor, a much higher melt flow index is achieved. The olefin polymer shown can be manufactured easily.

The production process of the Ziegler-Natta catalyst comprises the steps of preparing a magnesium carrier (a), supporting a transition metal compound on the carrier (b), and adding an internal electron donor (c).

There is no particular limitation on the source of magnesium included in the main catalyst component in step (a). Therefore, any magnesium compound used in the production of Ziegler-based catalysts for olefin polymerization, such as magnesium chloride, dialkoxymagnesium, alkoxymagnesium chloride, etc., can be used for the preparation of the catalyst component without limitation, and among them, recrystallized after dissolving in alcohol The method is preferred. This acts as a carrier having a spherical particle shape, which remains intact even with the polymer of the olefin.

There is no particular limitation on the source of the transition metal included in the main catalyst component in step (b), and therefore, any transition metal compound used in the production of the Ziegler-based catalyst for olefin polymerization may be used in the preparation of the catalyst component without limitation. In particular, it is preferable to use titanium metal, more preferably titanium tetrachloride.

Representative chemical formula of the transition metal compound in step (b) is as follows.

MXn (OR1) 4-n -------------------- (Formula 1)

In Formula 1, M is a metal, X is halogen, R1 is C1 to C10 hydrocarbyloxy, n is 0 to 4 as the oxidation number of the metal.

Preferably, in Chemical Formula 1, M is a group VB such as Ti, Zr, Hf, and Rf, group VB such as V, Nb, Ta, and Db, or group VB such as Cr, Mo, W, Sg, and X is Cl. , Br, I, and R 1 is C 1 -C 4 alkoxy or phenoxy. More preferably, in Formula 1, M is a group IVB, such as Ti, Zr, Hf, Rf, X is Cl, R1 is ethoxy, butoxy, chlorotriethoxy, dichlorodiethoxy, trichloro Oxy. Most preferably, in Chemical Formula 1, M is Ti and R 1 is Cl.

Representation of the internal electron donor in step (c) is as follows.

------------------ (Formula 2)

In Formula 2, R is hydrogen or alkyl, alkenyl, cycloalkyl, aryl or aryl substituents such as C 1 to C 20 linear, branched, and circular (Ar- (CH 2) n CH 3, Ar-halogen, Ar-OH, Ar- NO2, Ar-CF3, Ar-O (CH2) nCH3, etc.), alkylaryl or alkylaryl substituents (Ar- (CH2) nCH3, Ar-halogen, Ar-OH, Ar-NO2, Ar-CF3, Ar-O ( CH2) nCH3, etc.), and alkylaryl including heteroatoms.

Examples include 2-pyrrolidinone, 1-methyl-2-pyrrolidinone, and 1-ethyl-2-2-pyrrolidinone. pyrrolidone), 1-butyl-2-pyrrolidone, and 1-vinyl-2-pyrrolidinone.

Components of the solid catalyst prepared by the above method include 0.5 to 15% by weight of transition metal, 5 to 40% by weight of magnesium, 40 to 80% by weight of halogen, and 2.5 to 30% by weight of internal electron donor, based on the total weight of the catalyst.

In addition, the prepared solid catalyst has high activity, high stereoregularity and high hydrogen reactivity, and is preferably prepared in a form in which a transition metal compound is supported on a carrier for improving catalytic activity.

When the prepared solid catalyst is applied to olefin polymerization, the prepared catalyst is used as the main catalyst, the organoaluminum compound represented by the following Chemical Formula 3 is used as a promoter, and the external electron donor represented by the following Chemical Formula 4 is a subcatalyst. Used as

R ⁴ _n AlX _{3 -n} ------------------ (Formula 3)

In Chemical Formula 3, R ⁴ is C ₁ -C ₂₀ alkyl, X is halogen, n is 0-3.

R ⁵ _n Si (OR ⁶ ) _4-n ----------------------- (Formula 4)

In Formula 4, R ⁵ C ₁ to C ₂₀ Hydrocarbon, preferably C ₁ -C ₁₀ Alkyl, C ₅ to C ₁₂ cycloalkyl, C ₆ to C ₂₀ Aryl _, C ₁ to C ₁₀ Alkenyl, A ₁ to C ₁₀ Haloalkyl or C ₁ to C ₁₀ Aminoalkyl, chlorine, R ⁶ C ₁ to C ₂₀ Hydrocarbon, preferably C ₁ -C ₁₀ Alkyl, C ₅ -C ₁₂ Cycloalkyl, C ₆ to C ₂₀ aryl _, C ₁ to C ₁₀ Alkenyl, C ₂ ~ C ₁₀ Alkoxy alkyl.

The compound represented by the formula (4) is preferably an organic silicon compound, specifically triethylmethoxysilane, trimethylethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diisopropyldimethoxysilane, diphenyldimethoxy Silane, phenylmethyldimethoxysilane, diphenyldiethoxysilane, dicyclohexyldimethoxysilane, cyclohexylmethyldimethoxysilane, cyclohexylmethyldiethoxysilane, dicyclopentyldimethoxysilane, dicyclopentyl diethoxysilane, ethyl Trimethoxysilane, ethyltriethoxysilane, vinyltrimethoxysilane and vinyltriethoxysilane, preferably diphenyldimethoxysilane, cyclohexylmethyldimethoxysilane and dicyclopentyldiethoxysilane.

The external electron donor is used together with the promoter in the polymerization, and may be used if necessary. The concentration of the external electron donor includes 0.001 to 50 mol%, preferably 0.01 to 20 mol%, more preferably 0.02 to 10 mol% per mole of promoter. If the concentration of the external electron donor is less than 0.001 mol%, there is a problem that the improvement of stereoregularity does not occur.

When the solid catalyst according to the present invention is applied to olefin polymerization, polyolefins having high stereoregularity and activity of a polymer and a wide molecular weight distribution can be prepared.

In the present invention, 'polymerization' includes not only homopolymerization but also copolymerization.

The polymerization reaction can be carried out in gas phase, liquid phase, or solution phase. When performing a polymerization reaction in a liquid phase, a hydrocarbon solvent may be used and olefin itself can also be used as a solvent. The polymerization temperature is usually -50 to 350 ° C, preferably 0 to 200 ° C. If the polymerization temperature is less than -50 ° C, the activity of the catalyst is not good, and if it exceeds 350 ° C, the stereoregularity is poor, which is not good. The polymerization pressure is usually at normal pressure to 250 kg / cm 2, preferably at atmospheric pressure to 200 kg / cm 2, and the polymerization reaction can be carried out by any of batch, semi-continuous and continuous methods. When the polymerization pressure is 250 kg / cm 2 or more, it is not preferable from an industrial and economic point of view.

To the polyolefin prepared using the solid catalyst according to the present invention, a heat stabilizer, a light stabilizer, a flame retardant, carbon black, a pigment, an antioxidant, and the like, which are commonly added, may be added. In addition, the prepared polyolefin may be used in combination with low density polyethylene (LDPE), high density polyethylene (HDPE), polypropylene, polybutene, EP (ethylene / propylene) rubber and the like.

Hereinafter, preferred embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the following examples are provided only for the purpose of easier understanding of the present invention, and the present invention is not limited by the examples.

Example  Wow Comparative example  : Ziegler - Appear  Preparation of the catalyst

Example

In a high-purity nitrogen atmosphere, 4.8 g of anhydrous magnesium dichloride (MgCl 2), 20 ml of 2-ethylhexanol, 10 ml of propylene glycol, and 23 ml of decane were added to a double jacketed glass reactor with a stirrer, and the temperature was raised to 125 ° C., followed by a clear solution. Stir until it is produced. 1.4 g of phthalic anhydride was added thereto and stirred for 1 hour to prepare a magnesium carrier mixed solution. 30 mL of titanium tetrachloride (TiCl 4) and 60 mL of tutuene are added dropwise over 2 hours, and then the temperature is raised to 110 ° C. constantly.

Thereafter, 0.01 mol of 1-methyl-2-pyrrolidinone (1-methyl-2-pryrrolidinone) is added and reacted for 1 hour to obtain a precipitate. After washing the solid component with toluene, the temperature was lowered to 60 ° C., and then 30 mL of titanium tetrachloride and 100 mL of toluene were added and reacted for 1 hour. The solid component is washed with toluene and hexane to give a solid catalyst.

The polymerization of propylene was carried out using a 2 L polymerization reactor. The reactor was depressurized to 3 torr or less vacuum and charged with nitrogen of high purity three times. After filling 500 g of propylene and 750 cc of hydrogen at room temperature in a reactor, 3 mmol of triethylaluminum, 0.18 mmol of cyclohexylmethyldimethoxysilane, 0.0044 mmol of the catalyst prepared above were added, and the reactor was heated to 70 ° C. for 1 hour. After the reaction, the final polymer was obtained.

The polymer is used to measure activity, BD and MFR.

Comparative example

A solid catalyst was prepared in the same manner as in the Example, except that ethyl benzoate (0.01 mol) was used instead of 1-methyl-2-pyrrolidinone.

activation
kgPP / gCat BD
g / ml MFR
g / 10min Example 1 14.3 0.38 13 Comparative Example 1 16.8 0.40 7

* Unit volume stage mass (B.D): measured by ASTM 1895

* Melt Flow Index (MFR) (g / 10min): measured at 2.16kg load, 230 ℃, according to ASTM1238.

Claims (6)

 In the method of producing a Ziegler-Natta catalyst for olefin polymerization comprising the step of preparing a magnesium carrier (a), supporting a transition metal compound (b), adding an internal electron donor (c) , The internal electron donor used in the method for preparing the Ziegler-Natta catalyst for olefin polymerization is 2-pyrrolidinone having a structure of Chemical Formula 2 and its derivatives of the Ziegler-Natta catalyst for olefin polymerization. Manufacturing method.

------------------ Formula 2 Here, R is hydrogen or alkylaryl including alkyl, alkenyl, cycloalkyl, aryl or aryl substituents, alkylaryl or alkylaryl substituents, heteroatoms such as linear, branched, and circular. According to claim 1, wherein the internal electron donor is 2-pyrrolidinone (2-pyrrolidinone), 1-methyl-2-pyrrolidinone (1-methyl-2-pyrrolidinone), 1-ethyl-2-2-py 1-ethyl-2-pyrrolidone, 1-butyl-2-pyrrolidone, 1-vinyl-2-pyrrolidone Method for producing a Ziegler-Natta catalyst for olefin polymerization, characterized in that any one or more selected from the group consisting of. The method of claim 1, wherein the transition metal compound has a structure represented by Chemical Formula 1. A method for preparing a Ziegler-Natta catalyst for olefin polymerization. MX _n (OR ¹ ) _{4-n -------------------------} Formula 1 Here, M is a metal, X is halogen, R ¹ is C ₁ ~ C ₁₀ hydrocarbyl, and aryloxy, n is the oxidation number of the metal 0-4. The method of claim 3, wherein M is Ti, Zr, Hf, Rf IVB; Or C, Group V, Cr, Mo, W, Sg, X is Cl, Br, I, R ¹ is ethoxy, butoxy, chlorotriethoxy, dichlorodiethoxy, trichloroethoxy Method for preparing a Ziegler-Natta catalyst. The method of claim 1, wherein the source of magnesium in step (a) is magnesium chloride, dialkoxy magnesium or magnesium alkoxymagnesium chloride. A solid catalyst prepared by the method of any one of claims 1 to 5, wherein the constituents of the solid catalyst are 0.5 to 15% by weight of transition metal, 5 to 40% by weight of magnesium, and 40 to halogen, based on the total weight of the catalyst. Ziegler-Natta catalyst for olefin polymerization, characterized in that it comprises 80% by weight and 2.5-30% by weight of the internal electron donor.