KR101373774B1 - Preparing method of catalyst for polymerization of polyethylene and process for polymerization of polyethylene using the same - Google Patents

Abstract

The present invention relates to a production method of a catalyst for the synthesis of polyethylene and a synthesis method of polyethylene using the same. More specifically, the present invention relates to: a production method of a catalyst for the synthesis of polyethylene which comprises a step of making a magnesium compound react with alcohol and a compound denoted by chemical formula 1 to obtain a magnesium solution, and a step of making the magnesium solution react with tetrahydrofuran and a transition metal compound; and a synthesis method of polyethylene using the same.

Description

Preparation Method of Polyethylene Synthesis Catalyst and Production Method of Polyethylene Using the Same {PREPARING METHOD OF CATALYST FOR POLYMERIZATION OF POLYETHYLENE AND PROCESS FOR POLYMERIZATION OF POLYETHYLENE USING THE SAME}

The present invention relates to a method for producing a polyethylene synthesis catalyst, and a method for producing polyethylene using the same. More specifically, the preparation of the catalyst for polyethylene synthesis, which can not only show high reactivity in the polyethylene synthesis reaction, but also can easily prepare a catalyst which can easily control the properties such as molecular weight distribution, mechanical properties, etc. of the polyethylene to be synthesized. It relates to a method and a method for producing polyethylene using the same.

Existing polyethylene synthesis catalysts can be classified into Ziegler-Natta catalysts, chromium catalysts and metallocene catalysts according to the type of central metal used. These catalysts are selectively used depending on the production process and the application product because the catalyst activity, the molecular weight distribution characteristics of the polymer and the reaction characteristics to the comonomers are different from each other. Among these, Ziegler-Natta type catalysts are most used, and magnesium-supported catalysts and silica-supported catalysts are used according to the type of carrier.

Magnesium-supported catalysts react magnesium compounds with electron donors such as alcohols, amines, ethers, esters, carboxylic acids, etc. to prepare magnesium compound solutions, and rapidly cool the vacuum without reacting the prepared magnesium compound solutions with transition metal compounds. Drying, spray drying, etc. may be performed to prepare a spherical magnesium compound in solid form, and then reacted with a titanium compound to prepare a solid catalyst for polyethylene synthesis. In addition, there is a method for preparing a solid catalyst by reacting the prepared magnesium compound solution with a transition metal compound in a solution state.

In the method for producing a magnesium-supported catalyst, a method of forming particles without reacting a magnesium compound with a transition metal compound as a catalytically active material can produce a spherical solid catalyst carrier, and the resulting catalyst has a spherical shape. However, compared to the method for preparing a catalyst by directly reacting a magnesium compound solution with a transition metal compound, a complicated manufacturing process and a wide particle size distribution of a solid catalyst have a limitation in that the solid catalyst must be reclassified according to the particle size.

For example, US Patent No. 5,290,745 discloses a process of reducing magnesium oxide and titanium trichloride by reacting a metal magnesium and titanium tetrachloride solution to reduce the oxidation number of titanium, and a process of making the catalyst composition into catalyst particles through spray drying. have. However, this manufacturing method has a lot of process steps than the conventional catalyst preparation method, which is very complicated, has a high production cost, and takes a long time.

In addition, while a method of obtaining a solid catalyst by directly reacting a magnesium compound solution with a transition metal compound is inexpensive to manufacture, the particle shape of the final solid catalyst is not constant compared to the vacuum drying method described above, and there is a limit to controlling the particle size. exist.

Thus, without the need for complicated and additional catalytic post-treatment such as vacuum drying, a large spherical shape has a large surface area, which increases reactivity, has high catalytic activity, and can also improve physical properties of the synthesized polyethylene. There is a need for development of a method for producing a solid catalyst for polyethylene synthesis.

US Patent No. 5,290,745

The present invention can not only show high reactivity in the polyethylene synthesis reaction, but also a method for preparing a catalyst for polyethylene synthesis that can easily prepare a catalyst that can easily control the properties such as molecular weight distribution, mechanical properties, etc. of the polyethylene to be synthesized It is to provide.

In addition, the present invention is to provide a method for producing polyethylene using the polyethylene synthesis catalyst.

The present invention comprises the steps of preparing a magnesium solution by reacting a magnesium compound with an alcohol and a compound of Formula 1; And

It provides a method for producing a catalyst for polyethylene synthesis, comprising; reacting the magnesium solution with tetrahydrofuran and a transition metal compound.

[Chemical Formula 1]

In Formula 1, R ¹ is hydrogen, straight or branched alkyl of 1 to 20 carbon atoms (Alkyl), alkenyl (Alkenyl), cycloalkyl (Cycloalkyl), aryl (Aryl), aryl substituent, alkylaryl (Alkylaryl), Alkylaryl substituent or alkylaryl comprising N, O, S, or P.

In addition, the present invention provides a method for producing polyethylene, comprising the step of synthesizing an ethylene monomer in the presence of the catalyst for polyethylene synthesis.

Hereinafter, a method for preparing a catalyst for synthesizing polyethylene according to a specific embodiment of the present invention, and a method for producing polyethylene using the same will be described in more detail.

According to one embodiment of the invention, a method for preparing the catalyst for polyethylene synthesis may be provided.

The present inventors recognize that existing methods for producing a solid catalyst for synthesizing polyethylene used in the synthesis of polyethylene have to go through a complicated manufacturing process, or that there are limitations in that the size and shape of the resulting solid catalyst are not constant. Through the research on the preparation method of the catalyst for the synthesis of polyethylene that can be produced by using a recrystallization method of a solid catalyst containing a specific internal electron donor to confirm that the improved performance of the catalyst can be easily produced and completed the invention It was.

In particular, according to the production method, it is possible to prepare a catalyst having increased activity while having a large catalyst particles of a certain form, and the solid for polyethylene synthesis which can improve the physical properties of the resulting composite is improved performance of the catalyst The catalyst can be prepared simply.

The polyethylene synthesis is meant to include both a polymerization process using one ethylene monomer and a copolymerization process using two or more monomers.

According to an embodiment of the present invention, a magnesium compound is prepared by reacting an alcohol with a compound of Formula 1 to prepare a magnesium solution; And

A method for preparing a catalyst for polyethylene synthesis may be provided, the method comprising: reacting the magnesium solution with tetrahydrofuran and a transition metal compound.

[Chemical Formula 1]

In Formula 1, R ¹ is hydrogen, straight or branched alkyl of 1 to 20 carbon atoms (Alkyl), alkenyl (Alkenyl), cycloalkyl (Cycloalkyl), aryl (Aryl), aryl substituent, alkylaryl (Alkylaryl), Alkylaryl substituent or alkylaryl comprising N, O, S, or P.

The cycloalkyl group means a monovalent functional group derived from cycloalkane, and the aryl group means a monovalent functional group derived from arene. In addition, an alkylaryl group means the aryl group which the alkyl group substituted.

In the step of preparing the magnesium solution, the magnesium compound and the compound of Formula 1 may be reacted in a molar ratio of 1: 0.01 to 1: 1, preferably 1: 0.1 to 1: 0.2 molar ratio. If it is out of the above range, the catalyst particles may be formed small in size, or a catalyst having low activity and flowability may be prepared, which is not preferable.

Specific examples of the magnesium compound include magnesium halides, dialkoxy magnesium, alkylmagnesium halides, alkoxymagnesium halides, or aryloxymagnesium halides, and the use of magnesium halides is more preferable by increasing the activity of the catalyst.

Specifically, the magnesium halide compound is a compound having no reducing properties, and may be used magnesium chloride, magnesium dichloride, magnesium fluoride, magnesium bromide, magnesium iodide, phenoxy magnesium chloride, isoproxy magnesium chloride, butoxy magnesium chloride, Among them, the use of magnesium dichloride is preferred because it exhibits stable and high activity structurally and coordination with the transition metal compound which is the main active metal.

In the step of preparing the magnesium solution, the alcohol may react with the magnesium compound and the compound of Formula 1 in the preparation of the catalyst for polyethylene synthesis. The alcohol may dissolve the magnesium compound, and the magnesium compound may react with other compounds such as the compound of Formula 1, tetrahydrofuran, a transition metal compound, etc. in a completely dissolved state to help the growth of the catalyst particles. It is preferable because it can manufacture into large particle | grains. The reaction molar ratio of the magnesium compound and the alcohol may be 1: 1 to 1: 5, preferably 1: 2 to 1: 4. When the reaction molar ratio of the alcohol is more than 5 moles compared to the magnesium compound, in order to show high activity, the amount of the transition metal compound reacted with the magnesium compound needs to be increased, which is not preferable in terms of economics. It is not prepared in a homogeneous solution and is not preferred for growing the catalyst by reacting with a tetrahydrofuran compound.

The alcohol may be used without limitation as long as it is an alcohol known to be used for preparing a Ziegler-Natta catalyst for polyethylene synthesis. Specific examples of the solvent include ethanol, n-propanol, isopropanol, n-butanol, isobutanol, n-pentanol, isopentanol, neopentanol, cyclopentanol, n- Aliphatic or alicyclic alcohols such as dodecanol, 2-methylpentanol, 2-ethylbutanol and 2-ethylhexanol; Aryl cyclic alcohols such as cyclohexanol and methylcyclohexanol; Or aromatic alcohols such as benzyl alcohol, methyl benzyl alcohol, isopropyl benzyl alcohol, α-methyl benzyl alcohol, and the like; among these, aliphatic or alicyclic alcohols or alcohols having 2 or more carbon atoms are preferable, and 2-ethyl More preferably, hexanol is used.

In addition, in the step of preparing a magnesium solution by reacting the magnesium compound with an alcohol and the compound of Formula 1, the order or order of reacting the reactants is not particularly limited. For example, the magnesium compound and the alcohol and the compound of Formula 1 May be reacted simultaneously, or the components may be sequentially added and reacted.

However, in order to efficiently prepare a uniform magnesium solution, it is preferable to dissolve the magnesium compound in the alcohol, and then add and react the compound of Chemical Formula 1.

Preparing the magnesium solution may be performed at 80 to 140 ° C. That is, the dissolution temperature for dissolving the magnesium compound in the alcohol is preferably 80 to 140 ℃ and if it is out of the above range, the dissolution in alcohol is not good, or the side reactions increase is not preferable.

After dissolving the magnesium compound in alcohol, it can be sufficiently stirred to disperse the whole solution, and the compound of Formula 1 can be added to the product in which the magnesium compound is completely dissolved in alcohol.

In addition, the step of preparing the magnesium solution may be carried out under a solvent of a hydrocarbon. When reacting under a hydrocarbon solvent, a homogeneous solution of a magnesium compound and an alcohol can be obtained while using a small amount of alcohol.

Specific examples of the hydrocarbon solvent include aliphatic or alicyclic hydrocarbons having 5 to 20 carbon atoms, and among them, aliphatic or alicyclic hydrocarbon solvents having 6 to 17 carbon atoms are most preferred. More specific examples include aliphatic hydrocarbons such as hexane, heptane, octane, decane, dodecane, tetradecane, and mineral oil; Alicyclic hydrocarbons such as cyclic hexane, cyclic octane, methyl cyclic pentane and methyl cyclic hexane; And aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and cumene.

After preparing the magnesium solution, the magnesium solution may be reacted with tetrahydrofuran and a transition metal compound.

The transition metal compound means a transition metal of Group IVB, VB, or VIB or an organic compound containing such a transition metal. Specific examples of the transition metal include Ti, Zr, Hf, Rf, V, Nb, Ta , Db, Cr, Mo, W, and Sg.

Specific examples of the transition metal compound include any transition metal compound known to be used as a Ziegler-Natta catalyst for polyethylene synthesis, and can be used for preparing the catalyst component without limitation. In particular, preferred examples of the transition metal compound include compounds represented by the following formula (2).

(2)

MX _n (OR ² ) _4-n

In Formula 2, M is selected from the group consisting of transition metal elements of group IVB, VB, and VIB of the periodic table, X is halogen, R ² is an alkyl group having 1 to 10 carbon atoms, and n is 0 to 4 as oxidation number of the metal.

Preferred examples of M include Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W and Sg. Specific examples of the transition metal compound represented by Chemical Formula 2 include titanium tetrachloride, tetrabromium, tetraioditanium, tetrabutoxy titanium, tetraethoxy titanium, diethoxy titanium dichloride, or ethoxy titanium trichloride. It is possible to use titanium tetrachloride.

In addition, the tetrahydrofuran and the transition metal compound may be reacted by dispersing in a hydrocarbon solvent. This is to prepare a solid catalyst having a uniform particle size and a smooth surface by controlling the molar ratio of hydrocarbons. A solid catalyst for synthesizing polyethylene having a spherical shape with a uniform particle size distribution and a smooth surface of catalyst particles may be prepared by mixing in an amount within a range of 1 to 20 mol, more preferably 5 to 8 mol, of hydrocarbons, per mol of the magnesium compound. Can be.

Specific examples of the hydrocarbon solvent include aliphatic or alicyclic hydrocarbons having 5 to 20 carbon atoms, and among them, aliphatic or alicyclic hydrocarbon solvents having 6 to 17 carbon atoms are preferable. More specific examples include aliphatic hydrocarbons such as hexane, heptane, octane, decane, dodecane, tetradecane, and mineral oil; Alicyclic hydrocarbons such as cyclic hexane, cyclic octane, methyl cyclic pentane and methyl cyclic hexane; And aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and cumene. It is more preferable to use hexane in order to have a uniform particle size distribution of the solid catalyst to be produced and a smooth spherical surface of the catalyst particle surface.

Dispersing the tetrahydrofuran compound and the transition metal compound in a hydrocarbon solvent may be performed at -30 to 20 ℃. Dispersing the compounds in a hydrocarbon solvent at low temperature can form harder catalyst particles, thereby improving the polymerization activity of the catalyst and the apparent density of physical properties of the polyethylene synthesized.

In the step of reacting the magnesium solution with the tetrahydrofuran and the transition metal compound, the order or the order of reacting the reactants is not particularly limited, and for example, the magnesium solution, the tetrahydrofuran and the transition metal compound may be simultaneously reacted. In addition, the components may be sequentially added and reacted.

And, in order to form a catalyst having a uniform particle size, it can be reacted as follows. The hydrocarbon solvent and the transition metal compound may be first reacted, aged at a low temperature of −30 to 20 ° C. for 30 minutes to 2 hours, and then slowly added to the magnesium solution for 1 to 4 hours to react. In order to obtain a uniform particle size, it is preferable to add slowly at a constant rate, and it is preferable to add at a low temperature of -30 to 20 ° C so that recrystallization occurs easily.

After the reaction of the hydrocarbon solvent and the transition metal compound as described above, the reaction temperature of the reactant may be aged for 30 minutes to 1 hour by raising the temperature to 20 ℃ at a rate of 0.25 ℃ / min. The temperature of the reaction is gradually raised to 20 ° C to suppress the formation of non-uniform catalyst particles due to the radical reaction during initial catalyst particle formation.

After the aging process, tetrahydrofuran may be added and reacted at -30 to 60 ° C over 30 minutes, preferably at -20 to 30 ° C, and more preferably at 10 to 25 ° C. Do. Tetrahydrofuran plays a role of growing the size of the catalyst particles, it is preferable to add within the above temperature range to form a larger and harder catalyst. When the tetrahydrofuran is reacted at a temperature below -30 ° C, the size of the final catalyst particles may be small, which is not preferable. The catalyst of the large and hard form produced by administering the tetrahydrofuran is excellent in catalytic activity, and the apparent density of the polyethylene produced using the same is also effective in producing polyethylene.

The tetrahydrofuran is preferably reacted with 0.01 to 1 mole with respect to 1 mole of the magnesium compound.

The compound of Formula 1 may react with a tetrahydrofuran compound to generate an active site by donating electrons to a transition metal compound, and may act as an internal electron donor to impart activity of a catalyst. More specifically, the compound of Formula 1 may serve to generate catalyst particles and increase the size in the catalyst for polyethylene synthesis, and the tetrahydrofuran compound serves to largely and firmly improve the produced particles. can do. That is, by adding the two compounds, the polyethylene synthesis catalyst prepared by the above production method can be formed into large and hard spherical particles, and the catalyst has a good density of the polyethylene produced while maintaining excellent polymerization activity. The same physical properties can be improved.

As described above, the compound of Formula 1 and the tetrahydrofuran compound are preferably added to each step by step to prepare a catalyst, and when divided and administered, it is easier to form a catalyst of a larger particle than the reaction by administration together. It is preferable because it can maintain a high catalytic activity. More specifically, the polyethylene synthesis catalyst may be formed by growing the compound of Formula 1 to prepare a magnesium compound solution, to grow the particles, by adding tetrahydrofuran at an appropriate molar ratio at an appropriate temperature, the resulting catalyst The particles may be further grown and exhibit the physical properties of the catalyst described above. That is, the compound of Formula 1 and the tetrahydrofuran compound, there is a slight difference in the role to play in the formation of the catalyst, it is preferable to administer a high-performance catalyst efficiently to administer sequentially than administering them together Do.

The step of reacting the magnesium solution with the tetrahydrofuran and the transition metal compound may further include a step of heating to 0 to 80 ° C., aging, and washing. When hexane is used as a hydrocarbon solvent, it is preferable to heat up to 74 degreeC, and it is preferable to age for 2 hours. It is preferable to keep the maximum temperature below the boiling point of the hydrocarbon solvent in order to prevent the vaporization of the solvent, and the magnesium temperature, the transition metal compound and the tetrahydrofuran solution can be combined through the temperature increase process, and the particle size of the catalyst You can decide. The aged product may be cooled to 68 ° C. and washed 5-10 times with a hydrocarbon solvent to remove unreacted material and reaction residues to obtain a solid catalyst. More specifically, it is preferable to wash the solid catalyst using toluene as the aromatic hydrocarbon and hexane as the aliphatic or alicyclic hydrocarbon.

As described above, the method for preparing a polyethylene synthesis catalyst according to the embodiment of the present invention prepares the catalyst by a recrystallization method by reacting a low temperature magnesium compound solution with a transition metal compound in a simple and easily desired size and shape. It can be manufactured, mass production is easy and economic efficiency can be improved. In addition, the catalyst prepared as described above has a large spherical shape, the surface area is wide, the reactivity is increased, the catalytic activity is high, and the physical properties of the polyethylene synthesized using the catalyst can also be improved.

On the other hand, according to another embodiment of the present invention, in the presence of a catalyst prepared using the method for producing a catalyst for polyethylene synthesis, there may be provided a method for producing polyethylene comprising the step of synthesizing an ethylene monomer.

Polyethylene may be synthesized in the presence of a catalyst prepared using the method for preparing a polyethylene synthesis catalyst, and polyethylene may be synthesized in the presence of a catalyst system further including a promoter or an external electron donor. . Polyethylene synthesized using such a solid catalyst or catalyst system is a polymer having improved physical properties such as apparent density.

An external electron donor may be further included in the polyethylene synthesis process. The promoter may form an active site by reducing the transition metal compound to increase the catalytic activity. There is no particular limitation on the cocatalyst, and any organometallic compound known to be used in the preparation of a catalyst for general polyethylene synthesis may be used without limitation. Especially, it is preferable to use the alkyl aluminum compound represented by following formula (3).

(3)

R ³ _n AlX _{3- n}

In Chemical Formula 3, R ³ is an alkyl group having 1 to 8 carbon atoms, X is halogen, and n is 0 to 3.

Specific examples of the cocatalyst include trimethylaluminum, triethylaluminum, triisobutylaluminum, tributylaluminum, diethylaluminum dichloride, ethylaluminum dichloride, ethylaluminum sescuchloride, tripropylaluminum, tributylaluminum, and tripentyl Aluminum, trihexyl aluminum, trioctyl aluminum is mentioned.

In addition, the polyethylene production method may further include an external electron donor during synthesis. As the transition metal compound is reduced in the catalyst for synthesizing polyethylene, a part of the internal electron donor is removed, and the external electron donor may be bonded to the vacant site to proceed with the synthesis reaction.

The external electron donor may be used without particular limitation as long as it is an external electron donor commonly used in polyethylene synthesis, and in particular, it is preferable to use a silane-based compound represented by the following formula (4).

[Chemical Formula 4]

R ⁴ _n Si (OR ⁵ ) _4-n

In Formula 4, R ⁴ and R ⁵ are each independently hydrogen, a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, and 1 carbon atom. It may be an aminoalkyl group of 10 to 10, or an alkoxyalkyl group of 2 to 10 carbon atoms.

Specific examples of the external electron donor include cyclic hexylmethyldimethoxysilane, dicyclopentyldimethoxysilane, diisopropyldimethoxysilane, vinyltriethoxysilane, triethylmethoxysilane, trimethylethoxysilane, dicyclo Ethyl trimethoxy silane, diphenyl diethoxy silane, phenyl propyl dimethoxy silane, pentyl trimethoxy silane, tertiary butyl trimethoxy silane, cyclic hexyl ethyl dimethoxy silane , Cyclic hexylmethyldimethoxysilane, cyclopentyltriethoxysilane, diisobutyldiethoxysilane, isobutyltriethoxysilane, n-propyltrimethoxysilane, isopropyltrimethoxysilane, cyclic heptylmethyldiethoxy Silane, dicycloheptyldiethoxysilane, and the like.

The synthesis reaction may be carried out in a gas phase, a liquid phase, or a solution phase. When performing a synthesis reaction in a liquid phase, a hydrocarbon solvent can be used and ethylene itself can also be used as a solvent. The synthesis temperature may be 0 to 200 ° C, with a range of 50 to 150 ° C being preferred. If the synthesis temperature is less than 0 占 폚, the activity of the catalyst is not good, and if it exceeds 200 占 폚, the stereoregularity becomes poor, which is not preferable. The synthesis pressure may proceed at 1 to 100 atmospheres, preferably at 2 to 30 atmospheres. When the synthesis pressure exceeds 100 atm, it is not preferable from the industrial and economical viewpoints. The synthesis reaction can be carried out by any of batch, semi-continuous and continuous processes.

To the polyethylene produced 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 polyethylene may be used in combination with linear low density polyethylene (LLDPE), high density polyethylene (HDPE), polypropylene, polybutene, EP (ethylene / propylene) rubber and the like.

According to the present invention, not only can exhibit high reactivity in the polyethylene synthesis reaction, but also a method for producing a catalyst that can easily control the properties such as molecular weight distribution, mechanical properties, etc. of the polyethylene synthesized in a simple process and using the same Provided is a method for producing polyethylene.

1 is a SEM (Scanning Electron Microscope, SM-701, TOPCON) picture of the catalyst of Example 1.

The invention will be described in more detail in the following examples. However, the following examples are illustrative of the present invention, and the present invention is not limited by the following examples.

In the examples and comparative examples, the synthesis of the metal oxide catalyst was carried out under a nitrogen atmosphere, and a general synthesis method was used. Hexane, the reaction solvent, was purified by sieve and used a solvent having a water content of 10 ppm or less. 2-ethyl-hexanol (<15 ppm H ₂ O), decane (<10 ppm H ₂ O), ethyl benzoate (<15 ppm H ₂ O), tetrahydrofuran (<15 ppm H ₂ O), prepared the catalyst.

[ Example  And Comparative Example : Preparation of Catalysts and Synthesis of Polyethylene]

[ Example  One]

1) Preparation of Magnesium Compound Solution

In a nitrogen gas atmosphere, 90 g of magnesium chloride, 378 ml of decane, and 495 ml of ethyl hexanol were added in a nitrogen atmosphere using a 2-liter pressure-resistant glass reactor equipped with a circulating stirrer and an oil circulation heater. It was. In order to completely dissolve the magnesium compound, the temperature was raised to 135 ° C., and a homogeneous solution was aged for 1 hour, and 27 ml of ethyl benzoate solution was added for 30 minutes. After addition, the mixture was aged at 135 ° C. for 1 hour and the temperature of the reactor was reduced to 25 ° C. to prepare a magnesium compound solution.

2) solid Carrier  Production and Preparation of Solid Titanium Catalysts

The reactor temperature was cooled to -20 ° C. under a nitrogen atmosphere using a 2-liter pressure-resistant glass reactor equipped with a sus stirrer and an oil circulation heater. When the temperature of the reactor was maintained at -20 ° C, 1 liter of hexane and 342 ml of titanium tetrachloride solution were added thereto, followed by stirring at 300 rpm for 30 minutes. At the time of completion of stirring, 900 ml of the prepared magnesium compound solution was slowly added to the reaction solution for 4 hours. At this time, the temperature of the solution to be added was maintained at 4 ℃. When the addition of the magnesium compound solution was completed, the mixture was stirred for 30 minutes and the temperature of the reactor was raised at a rate of 0.25 ° C / min.

When the temperature of the reactor was 20 ℃ after aging for 30 minutes, 1 ml of tetrahydrofuran solution was added for 30 minutes. Next, the temperature of the reactor was raised to 73 ° C. at a rate of 1 ° C./min, and aged at 73 ° C. for 2 hours. The temperature of the reactor was cooled at a rate of 1 ° C./min to stop stirring at 68 ° C. and precipitate, and then the supernatant was removed and washed 7 times with 1000 ml of hexane. The final slurry was dried with nitrogen to give a catalyst.

3) Synthesis of Polyethylene

A 2 liter high pressure reactor heated at 125 ° C. was refluxed with nitrogen for 1 hour to bring the state of the high pressure reactor into a nitrogen atmosphere. The reactor was cooled to 25 ° C. under a nitrogen atmosphere and 1 liter of purified hexane was injected. 2 ml of triethylaluminum diluted in a decane solvent was added at a molar concentration, and 1 ml of a solution diluted in 100 ml of decane solvent was added to 1 g of the catalyst obtained above. After the addition, the temperature of the reactor was increased to 75 ° C. while stirring at 250 rpm. When the temperature of the reactor reached 70 ° C., 3000 ml of hydrogen was added, and 50 g of ethylene and butene were added at 75 ° C. over 2 hours to synthesize, and the temperature of the reactor was lowered to room temperature. The resulting polyethylene was weighed after drying for 6 hours in a vacuum oven at 50 ° C. and the apparent density and yield were measured, and the measurement results are shown in Table 1 below.

[ Example  2]

A catalyst was synthesized in the same manner as in Example 1 except that 4 ml of tetrahydrofuran solution was added instead of 1 ml of tetrahydrofuran solution, and polyethylene was synthesized.

[ Example  3]

A catalyst was synthesized in the same manner as in Example 1 except that 8 ml of tetrahydrofuran solution was added instead of 1 ml of tetrahydrofuran solution, and polyethylene was synthesized.

[ Example  4]

A catalyst was synthesized in the same manner as in Example 1 except that 16 ml of tetrahydrofuran solution was added instead of 1 ml of tetrahydrofuran solution, and polyethylene was synthesized.

[ Comparative Example  One]

A catalyst was synthesized and polyethylene was synthesized in the same manner as in Example 1 except that no tetrahydrofuran solution was added.

[ Comparative Example  2]

A catalyst was synthesized and polyethylene was synthesized in the same manner as in Comparative Example 1 except that 321 ml of titanium tetrachloride solution was added instead of 342 ml of titanium tetrachloride solution.

[ Comparative Example  3]

The catalyst was added in the same manner as in Comparative Example 1 except that 20 ml of ethyl benzoate solution and 13 ml of diisobutyl phthalate solution were added instead of 27 ml of ethyl benzoate solution and 415 ml of titanium tetrachloride solution instead of 342 ml of titanium tetrachloride solution. And polyethylene.

Ti content in catalyst components
(%) Catalyst particle size
(탆) Synthetic activity
(g-PE / g-cat) Polyethylene
Apparent density (g / ml) Example 1 3.3 20 28,000 0.32 Example 2 2.9 20 29,000 0.37 Example 3 2.8 20 31,000 0.36 Example 4 2.7 20 27,000 0.28 Comparative Example 1 3.5 20 27,000 0.31 Comparative Example 2 2.6 18 25,000 0.30 Comparative Example 3 4.0 12 34,000 0.29

Examples 1 to 4 relate to changes in catalyst particle size, synthetic activity, and physical properties of the resulting polyethylene according to the amount of tetrahydrofuran added. As shown in Table 1, it was confirmed that as the amount of tetrahydrofuran added is increased, both the synthetic activity and the apparent density of the resulting polyethylene show a tendency to increase. In addition, the size of the catalyst particles is also equal to or greater than the comparative example 20㎛, it was confirmed that the addition of the alkyl benzoate compound and tetrahydrofuran compound as an internal electron donor can easily synthesize a large catalyst .

On the contrary, Comparative Examples 1 to 3 showed poor catalytic activity and apparent density of polyethylene as compared to the catalysts of Examples 1 to 4 containing the tetrahydrofuran compound as a catalyst not containing the tetrahydrofuran compound. .

The size of catalyst particles and the catalytic activity and the apparent density of polyethylene tend to be inversely proportional, but the catalysts of Examples 2 to 3 have a large size of 20 μm, and the catalytic activity and the apparent density of polyethylene are excellent. It was confirmed to be effective and excellent for use.

In addition, as can be seen in the SEM picture of Figure 1, the polyethylene synthesis catalyst of Example 1 has a smooth surface in the form of a spherical shape, the conventional catalyst was prepared by directly reacting a magnesium compound solution and a transition metal compound The limitations of the method were improved.

Claims (12)

Preparing a magnesium solution by reacting a magnesium compound with an alcohol and a compound of Formula 1; And
A method for preparing a catalyst for polyethylene synthesis, comprising: reacting the magnesium solution with tetrahydrofuran and a transition metal compound;
[Chemical Formula 1]

In Formula 1, R ¹ is hydrogen, straight or branched alkyl of 1 to 20 carbon atoms (Alkyl), alkenyl (Alkenyl), cycloalkyl (Cycloalkyl), aryl (Aryl), aryl substituent, alkylaryl (Alkylaryl), Alkylaryl substituent or alkylaryl comprising N, O, S, or P.
The method of claim 1,
Method for producing a polyethylene synthesis catalyst in which the reaction molar ratio of the magnesium compound and the compound of formula 1 is 1: 0.01 to 1: 1.
The method of claim 1,
Method of producing a catalyst for polyethylene synthesis, wherein the reaction molar ratio of the magnesium compound and alcohol is 1: 1 to 1: 5.
The method of claim 1,
The step of preparing the magnesium solution is a method for producing a catalyst for polyethylene synthesis is carried out at 80 to 140 ℃.
The method of claim 1,
The step of preparing the magnesium solution is a method for producing a catalyst for polyethylene synthesis is carried out in the presence of a hydrocarbon solvent.
The method of claim 1,
The transition metal compound is a method for producing a polyethylene synthesis catalyst comprising a compound of the formula
(2)
MX _n (OR ² ) _4-n
In Formula 2, M is selected from the group consisting of transition metal elements of Group IVB, VB and VIB of the periodic table,
X is halogen,
R ² is an alkyl group having 1 to 10 carbon atoms,
n is from 0 to 4;
The method of claim 1,
The step of reacting the magnesium solution with the tetrahydrofuran and the transition metal compound further comprises the step of dispersing the tetrahydrofuran and the transition metal compound in a hydrocarbon solvent.
8. The method of claim 7,
The hydrocarbon solvent is a method for producing a polyethylene synthesis catalyst to add 1 to 20 moles of hydrocarbon to 1 mole of magnesium compound.
8. The method of claim 7,
Dispersing in the hydrocarbon solvent is a method for producing a catalyst for polyethylene synthesis is carried out at -30 to 20 ℃.
The method of claim 1,
Method of producing a catalyst for polyethylene synthesis is a reaction molar ratio of the magnesium compound and tetrahydrofuran 1: 0.01 to 1: 1.
The method of claim 1,
The step of reacting the magnesium solution, tetrahydrofuran and the transition metal compound is carried out at -30 to 60 ℃ a method for producing a polyethylene synthesis catalyst.
A method for producing polyethylene, comprising the step of synthesizing an ethylene-based monomer in the presence of a catalyst prepared using the method for producing a polyethylene synthesis catalyst according to any one of claims 1 to 11.

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