KR102754018B1 - Preparing method of catalyst for polymerization of polyethylene having a small particle - Google Patents

Abstract

The present invention relates to a method for producing a catalyst for polyethylene polymerization, and more specifically, to a method for producing a catalyst for polyethylene polymerization, comprising the steps of dissolving a magnesium compound in a mixed solvent of a hydrocarbon compound and an alcohol to produce a magnesium compound solution, and introducing a transition metal compound into the magnesium compound solution to cause a reaction; and a method for producing polyethylene, comprising the step of polymerizing or copolymerizing an ethylene monomer in the presence of a catalyst obtained by the method.

Description

{PREPARING METHOD OF CATALYST FOR POLYMERIZATION OF POLYETHYLENE HAVING A SMALL PARTICLE}

The present invention relates to a method for producing a catalyst for polyethylene polymerization having a small particle size, and more specifically, to a method for producing a catalyst for polyethylene polymerization having an average particle size of 1.0 ㎛ or less.

Among polyolefins, polyethylene, which is widely used, is classified into low-density polyethylene and high-density polyethylene according to density and performance. High-density polyethylene is mainly used for various containers, packaging films, fibers, pipes, packing, and insulating materials because it has excellent softening point, hardness, strength, and electrical insulation. In particular, high-density polyethylene has excellent mechanical properties, excellent chemical resistance and electrical insulation characteristics, and is used as a material for secondary battery separators because it is inexpensive.

Meanwhile, catalysts used to manufacture polyolefins can be divided into Ziegler-Natta catalysts, chromium catalysts, and metallocene catalysts depending on the type of central metal applied. Since these catalysts have different catalytic activity, hydrogen reactivity, molecular weight distribution, and reactivity characteristics for comonomers, they have been selectively used depending on the required characteristics of the manufacturing process and application products. Among these, Ziegler-Natta catalysts containing magnesium have advantages in terms of high activity, operating stability, excellent physical properties, and economic efficiency compared to other catalysts, and are thus most widely used in the manufacture of polyolefin polymers.

The Ziegler-Natta catalyst directly affects the properties and characteristics of the polyolefin produced, depending on its composition, structure, and manufacturing method. Therefore, in order to change the properties of the polyolefin produced, the composition of the catalyst, the structure of the support, and the manufacturing method of the catalyst must be changed during the manufacturing of the catalyst, and research on the activity of the catalyst and the molecular weight and stereoregularity of the polymerized polymer that change due to the manufacturing method of each catalyst or the difference in the composition must also be conducted in parallel. In particular, the catalyst particle size and distribution are very important in manufacturing a polymer that is advantageous for product molding.

When the polymer particle size is large, blow molding and film molding are possible, but it is difficult to apply to membranes and additive products. When the polymer particle size is large, the chlorine addition reaction to the polymer does not occur well, and there is a problem that limits the application to membrane products. In addition, in the case of additives, if the polyethylene particles are large, the flowability is hindered and the product performance is impaired. Therefore, it is necessary to manufacture a catalyst that can control the polymer particle size to be small.

The methods for manufacturing such catalysts include the support method and the recrystallization method, which are widely used to date. The catalyst using the support method is manufactured by bonding titanium to MgCl ₂ , and the catalyst particle size, shape, and particle size distribution are determined according to the MgCl ₂ particle size, shape, and particle size distribution. This MgCl ₂ support manufacturing method is described in Patent Publication No. 4307209. The catalyst is manufactured by adding ethanol to MgCl ₂ to easily bond titanium, and such a catalyst is difficult to control the particle size and has a wide particle size distribution. In addition, the polymer generated when applying the catalyst has a wide particle size distribution and large particle size, making it difficult to apply to products.

In addition, Patent Publication No. 10-0172607 discloses a catalyst prepared by dissolving MgCl ₂ , combining it with titanium, and then recrystallizing at a low temperature. The catalyst discloses that the catalyst has a small catalyst particle size and high polymerization activity by using an excessive amount of titanium, thereby obtaining a large amount of polymer. However, the polymer produced when the catalyst is applied has the disadvantage of having a small particle size, a large amount of fine powder, and a wide distribution.

Therefore, there is still a need for the development of a catalyst for polyethylene polymerization that has a small particle size, a constant shape, and can polymerize ethylene polymers with a narrow particle size distribution during polyethylene polymerization.

Patent Registration No. 10-0172607

One aspect of the present invention is to provide a method for producing a catalyst capable of polymerizing an ethylene polymer having a narrow particle size distribution during a polyethylene polymerization reaction.

According to one aspect of the present invention, a method for producing a catalyst for polyethylene polymerization is provided, comprising the steps of: preparing a magnesium compound solution by dissolving a magnesium compound in a mixed solvent of a hydrocarbon compound and an alcohol; and introducing a transition metal compound into the magnesium compound solution and causing a reaction.

According to the present invention, a method for producing a catalyst capable of polymerizing polyethylene having a small particle size suitable for product application and a narrow particle size distribution is provided, and thus, by means of this catalyst, polyethylene suitable for various product applications, such as membranes, additives, etc. for coating, lubrication, wear resistance, chemical resistance, etc., can be polymerized.

Figure 1 shows a SEM (Scanning Electron Microscope, SM-701, TOPCON) image of an exemplary catalyst manufactured according to the present invention.
Figure 2 shows a SEM (Scanning Electron Microscope, SM-701, TOPCON) image of polyethylene polymerized according to an exemplary catalyst of the present invention.

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

Any numerical ranges listed herein include all values between the lower value and the higher value, in increments of one unit, provided there is at least a difference of two units between any lower value and any higher value.

The term "composition" as used in the present invention includes a mixture of substances including not only the composition but also decomposition products and reaction products formed from the materials of the composition.

The term "polymer" used in the present invention is a polymer compound prepared by polymerization of monomers of the same or different types. "Polymer" includes homopolymers and copolymers.

The present invention provides a method for producing a catalyst for polyethylene polymerization having an average particle size of 1.0 ㎛ or less, and an ethylene polymer obtained after polymerization using the catalyst has the characteristic of exhibiting a narrow particle size distribution with a particle size of 50 ㎛ or less.

More specifically, the method for producing a polyethylene polymerization catalyst of the present invention includes the steps of preparing a magnesium compound solution by dissolving a magnesium compound in a mixed solvent of a hydrocarbon compound and an alcohol; and the steps of introducing a transition metal compound into the magnesium compound solution and causing a reaction.

In the step of preparing a magnesium compound solution by dissolving the magnesium compound in a mixed solvent of a hydrocarbon compound and an alcohol, as a specific example of the magnesium compound, the magnesium compound may be at least one compound selected from the group consisting of magnesium halide, dialkoxy magnesium, (C ₁ -C ₂₀ )alkyl magnesium halide, (C ₁ -C ₂₀ )alkoxy magnesium halide, and (C ₆ -C ₂₀ )aryloxy magnesium halide.

Specifically, magnesium halide compounds are non-reducing compounds, and examples of which may be used include magnesium chloride, magnesium dichloride, magnesium fluoride, magnesium bromide, magnesium iodide, phenoxy magnesium chloride, isopropoxy magnesium chloride, and butoxy magnesium chloride. Among these, magnesium dichloride is preferable because it is structurally and coordinationally stable with the transition metal compound, which is the main active metal, and exhibits high activity. In addition, magnesium halide compounds may be used in combinations of two or more. The magnesium halide compound may form a complex or complex compound with an organometallic compound of another metal, such as aluminum, zinc, boron, sodium, or potassium, or may be a mixture with these metal compounds.

In the present invention, any alcohol known to be used in the production of a Ziegler-Natta catalyst for polyethylene polymerization can be used without limitation. Specifically, aliphatic or alicyclic alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, n-pentanol, isopentanol, neopentanol, cyclopentanol, n-hexanol, n-heptanol, n-octanol, decanol, dodecanol, 2-methylpentanol, 2-ethylbutanol, 2-ethylhexanol, and the like; aromatic alcohols such as cyclohexanol, methylcyclohexanol, and α-methylbenzyl alcohol can be used, and among these, it is preferable to use an aliphatic or alicyclic alcohol or an alcohol having 2 or more carbon atoms, and it is more preferable to use 2-ethylhexanol.

In the present invention, alcohol plays a role in improving the catalytic performance by dissolving the magnesium compound and forming appropriate pores by bonding with the magnesium compound within the catalyst. In one embodiment of the present invention, alcohol is used in an amount of 3 to 4 moles per 1 mole of the magnesium compound. If the amount of alcohol used is less than 3 moles per 1 mole of the magnesium compound, the activity is low when the alcohol is added, and on the other hand, if it exceeds 4 moles, the loading rate of the transition metal compound is low and the catalyst particle size is large, which is a disadvantage.

In the present invention, the hydrocarbon compound serves to facilitate dispersion of the magnesium compound. If the hydrocarbon compound is not used, the magnesium compound may form a hard lump when in contact with alcohol and may be difficult to dissolve.

Specific examples of the hydrocarbon compound include aliphatic or alicyclic (C ₉ -C ₂₅ ) hydrocarbons, and among them, aliphatic or alicyclic (C ₉ -C ₁₇ ) hydrocarbon compounds are most preferable. More specific examples include aliphatic hydrocarbons such as decane, dodecane, tetradecane, and mineral oil having 5 to 25 carbon atoms (e.g., Cas No. 8042-47-5, etc.); 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, and among these, it is preferable to use a solvent having a boiling point of 150 ^o C or higher, and it is more preferable to use decane.

The amount of the hydrocarbon compound used for smooth dispersion of the magnesium compound may be too small or too large, making it difficult to control the catalyst particle size and the transition metal compound and donor loading ratio difficult. Therefore, the hydrocarbon compound is suitably used in an amount of 2 to 4 moles per 1 mole of the magnesium compound. If the amount of the hydrocarbon compound used is less than 2 moles per 1 mole of the magnesium compound, the magnesium compound is not dispersed well, while if it exceeds 4 moles, the catalyst particle size and the loading ratio of the transition metal compound may decrease, making it difficult to control.

In the present invention, the step of preparing the magnesium compound solution can be performed at 75 to 150°C. The dissolution temperature for dissolving the magnesium compound in the solvent is preferably 80 to 140°C, and if it is outside the above range, the magnesium compound may not dissolve well in alcohol or side reactions tend to increase.

Meanwhile, prior to the step of introducing the transition metal compound and reacting, a step of introducing an internal electron donor into the magnesium compound solution and reacting may be additionally included. The reaction molar ratio of the magnesium compound and the internal electron donor compound in the step of mixing and reacting the internal electron donor compound is 1:0.01 to 1:1, preferably 1:0.01 to 1:0.3, and if it is out of the above range, the formation of transition metal particles to be supported on the catalyst to be manufactured may be prevented, thereby lowering the activity of the catalyst.

Internal electron donors used include benzoate compounds, dialkoxybenzene compounds, and organosilicon compounds. Specific examples of the above benzoate compounds include ethyl benzoate, methyl benzoate, propyl benzoate, isopropyl benzoate, tibutyl benzoate, tibutyl 4-(2-aminoethyl) benzoate, ethyl 4-(dimethylamino) benzoate, ethyl 4-(butylamino) benzoate, ethyl 4-(bromomethyl) benzoate, ethyl 4-(benzyloxy) benzoate, methyl 4-(hydroxymethyl) benzoate, methyl 4-(aminomethyl) benzoate, methyl 3-(aminocarbonyl) benzoate, methyl 4-(2-hydroxyethoxy) benzoate, methyl 4-(cyanomethyl) benzoate, methyl 4-(bromomethyl) benzoate, and methyl Examples include 3-(bromomethyl)benzoate.

Specific examples of the above dialkoxybenzene compounds include 1,2-dimethoxybenzene, 1,2-diethoxybenzene, 1,2-dibutoxybenzene, 1,2-di-sec-butoxybenzene, and 1,2-di-tert-butoxybenzene.

Specific examples of the above organosilicon compounds include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, vinyltrimethoxysilane, methyltrimethoxysilane, n-propyltriethoxysilane, tetryltrimethoxysilane, cyclopentyltrimethoxysilane, 2-methylcyclophenyltrimethoxysilane, 2,3-dimethylcyclopentyltrimethoxysilane, phenyltrimethoxysilane, vinyltriethoxysilane, t-butyltriethoxysilane, n-butyltriethoxysilane, iso-butyltriethoxysilane, decyltriethoxysilane, cyclopentyltriethoxysilane, cyclohexyltriethoxysilane, chlorotriethoxysilane, ethyltriisopropoxysilane, Examples thereof include vinyltributoxysilane, trimethylphenoxysilane, methyltriallyloxysilane, vinyltriacetoxysilane, dimethylmethoxysilane, diisopropyldimethoxysilane, t-butylmethyldimethoxysilane, dicyclopentyldimethoxysilane, dicyclohexyldimethoxysilane, cyclohexylmethyldimethoxysilane, diphenyldimethoxysilane, and cyclopentyldimethyloxysilane.

It is preferable that the molar ratio of the magnesium compound and the transition metal compound is 1:3 to 1:8. That is, the transition metal compound can be used in an amount of 3 to 8 mol per 1 mol of the magnesium compound, and if the amount of the transition metal compound used is less than 3 mol per 1 mol of the magnesium compound, the loading rate of the transition metal compound may be low, thereby reducing the activity, and if it exceeds 8 mol, the loading rate of the transition metal compound increases more than necessary, thereby reducing the pores in the catalyst, thereby reducing the activity, and the metal residue rate in the polymer may increase, which may increase human hazard and environmental pollution.

Meanwhile, in the present invention, it is preferable that the transition metal compound is introduced at a rate of 5 to 10 ml/hour, and for example, it can be introduced at a rate of 6 to 9 ml/hour. In one embodiment of the present invention, the introduction time of the transition metal compound is appropriately 1 to 6 hours, for example, 1 to 3 hours. If the introduction of the transition metal compound is less than 1 hour, the activity increases, but the apparent density may decrease, and the catalyst shape may not be good. In addition, if the introduction of the transition metal compound is more than 6 hours, the catalyst surface may be smooth and the activity may exhibit a characteristic of decreased.

The addition of the transition metal compound can be performed under stirring at a speed of 50 to 1000 rpm depending on the total volume being reacted. If the stirring speed is too slow, there is a risk that the catalyst particles formed after combining with the transition metal compound will agglomerate and increase in particle size.

Meanwhile, the introduction of the transition metal compound may be done gradually, thereby preventing temperature generation and catalyst agglomeration. In addition, considering the temperature increase after the introduction of the transition metal compound is completed, the temperature may be maintained at the same temperature for a certain period of time, for a non-limiting example, 30 to 90 minutes, and then the temperature may be gradually increased. Typically, the temperature is appropriately increased at a rate of 0.1 to 0.5 ℃/min. If the temperature is suddenly and rapidly increased, the catalyst may break or agglomerate, thereby changing the shape of the catalyst. Thereafter, the temperature is gradually increased again to reach 60 to 80 ℃. At this time, only by gradually increasing the temperature can the phenomenon of the catalyst breaking or agglomeration be prevented and a rapid reaction due to the temperature increase can be controlled. Thereafter, the reaction is maintained for 2 to 3 hours, for example, at 60 to 80 ℃, so that the substances in the catalyst can stably bind and react.

At this time, the step of adding a transition metal compound to the magnesium compound solution and reacting can be performed at a temperature of -20 to 10°C, preferably -15 to 5°C. The transition metal compound can be added to the magnesium compound solution maintained at the above temperature. That is, the transition metal compound is added at -20 to 10°C, and the catalyst particle size can vary depending on the temperature at which it is added. If the transition metal compound is added above 10°C, the catalyst particle size becomes smaller, the catalyst particle size distribution becomes wider, and the hardness of the catalyst decreases, which lowers the apparent density and increases the formation of fine particles. On the other hand, if the transition metal compound is added below -20°C, the catalyst particle size can increase.

In the present invention, when performing the step of introducing a transition metal compound into the magnesium compound solution and causing a reaction, a nonpolar solvent is used before introducing the transition metal and mixing is not performed. As a result, the crystallization speed is slowed when the magnesium compound and the transition metal are combined, so that particle formation is delayed, and accordingly, a catalyst having a small particle size can be manufactured. When a magnesium compound (solution) is introduced into a transition metal, the crystallization speed progresses very quickly and the particles become large, but when a transition metal is added to a magnesium compound (solution) as in the present invention, the crystallization speed is slowed. In addition, when a transition metal mixed with a nonpolar solvent is used, the catalyst particle size becomes large. Therefore, the present invention can manufacture a catalyst having a small particle size by adding a transition metal to a magnesium compound mixed with a nonpolar solvent, without mixing the transition metal with a nonpolar solvent.

That is, in the present invention, a magnesium compound solution is prepared by minimizing the nonpolar solvent, and a transition metal compound is added thereto to slow down the crystallization rate, thereby producing a catalyst having small particles.

In a catalyst composition for polyethylene polymerization, the internal electron donor can be used together with a transition metal compound to increase the activity of the catalyst in a polyethylene polymerization reaction and to improve the stereoregularity and hydrogen reactivity of the polyethylene produced.

Preferred internal electron donors are, for example, ethyl benzoate, methyl benzoate, propyl benzoate, isopropyl benzoate, tibutyl benzoate, tibutyl 4-(2-aminoethyl) benzoate, ethyl 4-(dimethylamino) benzoate, ethyl 4-(butylamino) benzoate, ethyl 4-(bromomethyl) benzoate, ethyl 4-(benzyloxy) benzoate, methyl 4-(hydroxymethyl) benzoate, methyl 4-(aminomethyl) benzoate, methyl 3-(aminocarbonyl) benzoate, methyl 4-(2-hydroxyethoxy) benzoate, methyl 4-(cyanomethyl) benzoate, methyl 4-(bromomethyl) benzoate and methyl 3-(Bromomethyl)benzoate, 1,2-dimethoxybenzene, 1,2-diethoxybenzene, 1,2-dibuthoxybenzene, 1,2-di-sec-butoxybenzene, 1,2-di-tert-butoxybenzene, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, vinyltrimethoxysilane, methyltrimethoxysilane, n-propyltriethoxysilane, tetryltrimethoxysilane, cyclopentyltrimethoxysilane, 2-methylcyclophenyltrimethoxysilane, 2,3-dimethylcyclopentyltrimethoxysilane, phenyltrimethoxysilane, vinyltriethoxysilane, t-butyltriethoxysilane, It is preferable to use at least one compound selected from the group consisting of n-butyltriethoxysilane, iso-butyltriethoxysilane, decyltriethoxysilane, cyclopentyltriethoxysilane, cyclohexyltriethoxysilane, chlorotriethoxysilane, ethyltriisopropoxysilane, vinyltributoxysilane, trimethylphenoxysilane, methyltriallyloxysilane, vinyltriacetoxysilane, dimethylmethoxysilane, diisopropyldimethoxysilane, t-butylmethyldimethoxysilane, dicyclopentyldimethoxysilane, dicyclohexyldimethoxysilane, cyclohexylmethyldimethoxysilane, diphenyldimethoxysilane, and cyclopentyldimethyloxysilane.

In addition, in addition to the compound of the above chemical formula 1, various internal electron donor compounds known in the art may be additionally included, such as succinate compounds, silane compounds, fluorene compounds, or mixtures thereof.

In this specification, a cycloalkyl group means a monovalent functional group derived from a cycloalkane, and an aryl group means a monovalent or divalent functional group derived from arene, which is an aromatic hydrocarbon. In addition, an alkylsilyl group means a silyl group substituted with an alkyl group, an arylalkyl group means an alkyl group substituted with an aryl group, and an alkylaryl group means an aryl group substituted with an alkyl group.

Specific examples of the transition metal compound that can be used in the present invention include, without limitation, any transition metal compound known to be used as a Ziegler-Natta catalyst for polyethylene polymerization. In particular, preferred examples of the transition metal compound include compounds represented by the following chemical formula 1.

[Chemical Formula 1]

MX _n (OR ¹ ) _{4 -n}

(In the above chemical formula 1,

M is selected from the group consisting of transition metal elements of groups IVB, VB and VIB of the periodic table,

X is a halogen,

R ¹ is a (C ₁ -C ₁₀ ) alkyl group,

n is the oxidation number of the metal, from 0 to 4.)

Preferable examples of the above M include Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, etc., and a transition metal compound containing at least one of these can be used. In addition, specific examples of the transition metal compound of the above chemical formula 3 include titanium tetrachloride, titanium tetrabromide, titanium iodide, tetrabutoxy titanium, tetraethoxy titanium, diethoxy titanium dichloride, zirconium tetrachloride, chromium chloride, or ethoxy titanium trichloride, and it is preferable to use zirconium tetrachloride [Zirconium(IV) chloride], chromium chloride [Chromium(III) chloride], titanium tetrachloride, or a combination thereof.

Meanwhile, the halogen X may be fluorine, chlorine, bromine or iodine.

In one embodiment of the present invention, examples of the transition metal compound include TiCl ₄ , TiBr ₄ , TiCl ₃ , Ti(OC ₂ H ₅ ) ₃ Cl, Ti(OC ₂ H ₅ ) ₃ Br, Ti(OC ₃ H ₇ ) ₂ Cl ₂ , Ti(OC ₆ H ₅ ) ₂ Cl ₂ , and Ti(OC ₂ H ₅ )Cl ₃ . Mixtures of such transition metal compounds can also be used.

The method for producing a catalyst for polyethylene polymerization of the present invention may additionally include a step of reacting with an alkyl aluminum compound including a unit represented by the following chemical formula 2.

[Chemical formula 2]

AlR ² _m X _{3 -m}

(In the above chemical formula 2,

R ² is a (C ₁ -C ₈ ) alkyl group,

X is a halogen,

m is 0 to 3.)

The above alkyl aluminum compound can act as a cocatalyst to reduce a transition metal compound to form an active site, thereby increasing catalytic activity. In particular, when a transition metal compound is reacted first and then the alkyl aluminum compound is reacted, the transition metal active sites can be distributed more evenly, thereby exhibiting higher catalytic activity and producing polyethylene having a wide molecular weight distribution and improved processability.

Specific examples of such alkyl aluminum compounds that can be used include triethylaluminum, trimethylaluminum, triisopropylaluminum, trioctylaluminum, diethylaluminum chloride, diethylaluminum bromide, diethylaluminum iodide, diethylaluminum fluoride, ethylaluminum dichloride, dimethylaluminum chloride, and methylaluminum dichloride.

In addition, the alkyl aluminum compound can be reacted in an amount of 0.01 to 10 moles per 1 mole of the transition metal compound, and preferably 1:0.01 to 1:2. If the amount of the alkyl aluminum compound used is too little or too much, the activity of the catalyst may decrease.

The step of reacting with the above-mentioned catalyst can be performed at -30 to 100°C, and particularly preferably 0 to 30°C. In addition, it is preferable that the contact time be sufficiently 0.5 to 24 hours from the time the reaction takes place.

Meanwhile, the method for producing polyethylene of the present invention does not use an additional external electron donor. In the case of a recrystallization catalyst, when solid particles are formed, most of them are bonded with the donor, so the donor added after particle formation may not form a structurally stable bond and may not be helpful in polymerization.

The above alkyl aluminum compound can be dispersed in a hydrocarbon compound and reacted as needed. Specific examples of the hydrocarbon compound include aliphatic or alicyclic (C ₅ -C ₂₀ ) hydrocarbons, and among them, aliphatic or alicyclic (C ₆ -C ₁₇ ) hydrocarbon compounds 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.

The polyethylene polymerization catalyst of the present invention may be a solid catalyst and may have an average particle diameter of 1.0 ㎛ or less, for example, 0.1 ㎛ to 1.0 ㎛, or 0.5 ㎛ to 0.9 ㎛. The average diameter of the polyethylene polymerization catalyst means the average diameter of a plurality of polyethylene polymerization catalyst solid particles.

Furthermore, the polyethylene polymerization catalyst of the present invention may additionally include excipients or additives commonly employed in the technical field to which the present invention belongs, in addition to the internal electron donor, transition metal compound, cocatalyst, etc. described above.

According to another aspect of the present invention, a method for producing polyethylene is provided, which comprises a step of polymerizing or copolymerizing an ethylene monomer in the presence of a catalyst obtained by the method for producing a polyethylene polymerization catalyst of the present invention as described above.

At this time, the reaction for polyethylene polymerization can be carried out in the gas phase, liquid phase, or solution phase. When carrying out the polymerization reaction in the liquid phase, a hydrocarbon compound can be used, and ethylene itself can also be used as a solvent.

The polymerization temperature may be 0 to 200°C, and is preferably in the range of 30 to 150°C. If the polymerization temperature is lower than 0°C, the activity of the catalyst is not good, and if it exceeds 200°C, the stereoregularity deteriorates, which is not preferable. The polymerization pressure may be 1 to 100 atm, and is preferably 2 to 40 atm. If the polymerization pressure exceeds 100 atm, it is not preferable from an industrial and economical standpoint. The polymerization reaction may be performed by any of a batch, semi-continuous, or continuous method.

Meanwhile, the polyethylene manufactured using the solid catalyst according to the present invention can be added with conventionally added heat stabilizers, light stabilizers, flame retardants, carbon black, pigments, antioxidants, etc. In addition, the manufactured polyethylene can be used in a mixture with linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), high-density polyethylene (HDPE), EP (ethylene/propylene) rubber, etc.

In this way, according to the present invention, a method for producing a catalyst capable of polymerizing polyethylene having a small particle size suitable for product application and a narrow particle size distribution can be obtained, and by means of this catalyst, polyethylene suitable for various product applications, such as a separation membrane, an additive, etc. for coating, lubrication, wear resistance, chemical resistance, etc., can be polymerized.

Hereinafter, the present invention will be described more specifically through specific examples. The following examples are merely examples to help understand the present invention, and the scope of the present invention is not limited thereto.

Example

1. Preparation of catalyst and polymerization of polyethylene

Example 1: Preparation of catalyst and polyethylene

(1) Preparation of solid catalyst

In a 0.5 L pressure-resistant glass reactor equipped with a stirrer and an oil circulation heater, 3.0 g of magnesium dichloride, 16 ml of 2-ethylhexanol, and 15 ml of decane were charged under a nitrogen atmosphere, and stirred at 300 rpm at 80 °C. The temperature was increased to 130 °C to completely dissolve the magnesium dichloride, and when a homogeneous solution was obtained, the reaction was maintained for 1 hour, and 0.2 ml of ethyl benzoate was added. After the addition, the reaction was maintained at the same temperature for 1 hour, and when the temperature was maintained at -10 °C, 16 ml of titanium tetrachloride was added for 2 hours while stirring at 600 rpm. Upon completion of the addition, the temperature was increased to 70 °C and maintained at the same temperature for 1 to 5 hours, and then lowered to 45 °C to stop stirring, and the generated solid particles were precipitated. Thereafter, the supernatant was removed, washed five times with 2 L of hexane, and dried to obtain a catalyst.

(2) For manufacturing and polymerizing polyethylene

A 2-liter stainless steel autoclave dried at 120°C for 2 hours was purged with nitrogen to create a nitrogen atmosphere inside the reactor. While maintaining the nitrogen atmosphere, the temperature inside the reactor was lowered to 25°C, and 1 liter of purified hexane was injected. 2.0 mmol of triethylaluminum diluted in hexane was added, and 1 ml of the diluted solution obtained by diluting 1 g of the catalyst obtained above in 100 ml of decane was added. After the addition, the reactor temperature was raised to 75°C while stirring at 250 rpm. Thereafter, 2.2 bar of _H2 and 7.1 bar of ethylene were supplied to maintain the pressure. Polymerization was usually continued for 2 hours, and the pressure was maintained constant by supplying ethylene. After completion of the reaction, the solvent was removed by performing reduced pressure filtration, and the residual hexane solvent was dried in a vacuum oven at 80°C for 6 hours to obtain a polymer.

The results of measuring the properties of the catalyst and polymer after polymerization are shown in Table 1.

Example 2: Preparation of catalyst and polyethylene

A catalyst and polyethylene were prepared in the same manner as in Example 1, except that the titanium tetrachloride injection temperature was set to -5°C.

Example 3: Preparation of catalyst and polyethylene

A catalyst and polyethylene were prepared in the same manner as in Example 1, except that the titanium tetrachloride injection temperature was set to 0°C.

Example 4: Preparation of catalyst and polyethylene

A catalyst and polyethylene were prepared in the same manner as in Example 1, except that the titanium tetrachloride injection temperature was set to 5°C.

Example 5: Preparation of catalyst and polyethylene

A catalyst and polyethylene were prepared in the same manner as in Example 1, except that the titanium tetrachloride injection temperature was set to 10°C.

Example 6: Preparation of catalyst and polyethylene

A catalyst and polyethylene were prepared in the same manner as in Example 1, except that 23 ml of 2-ethylhexanol was added instead of 16 ml of 2-ethylhexanol in Example 1.

Example 7: Preparation of catalyst and polyethylene

A catalyst and polyethylene were prepared in the same manner as in Example 1, except that 25 ml of decane was added instead of 15 ml of decane in Example 1.

Example 8: Preparation of catalyst and polyethylene

A catalyst and polyethylene were prepared in the same manner as in Example 1, except that ethyl benzoate was not added.

Example 9: Preparation of catalyst and polyethylene

A catalyst and polyethylene were prepared in the same manner as in Example 1, except that 0.3 ml of ethyl benzoate was added instead of 0.2 ml of ethyl benzoate in Example 1.

Example 10: Preparation of catalyst and polyethylene

A catalyst and polyethylene were prepared in the same manner as in Example 1, except that 0.2 ml of tetraethoxysilane was added instead of 0.2 ml of ethyl benzoate.

Example 11: Preparation of catalyst and polyethylene

A catalyst and polyethylene were prepared in the same manner as in Example 1, except that 0.3 ml of tetraethoxysilane was added instead of 0.2 ml of ethyl benzoate.

Example 12: Preparation of catalyst and polyethylene

A catalyst and polyethylene were prepared in the same manner as in Example 1, except that 0.1 ml of 1,2-dimethoxybenzene was added instead of 0.2 ml of ethyl benzoate in Example 1.

Example 13: Preparation of catalyst and polyethylene

A catalyst and polyethylene were prepared in the same manner as in Example 1, except that 0.2 ml of 1,2-dimethoxybenzene was added instead of 0.2 ml of ethyl benzoate in Example 1.

Comparative Example 1: Preparation of catalyst and polyethylene

In a 0.5 L pressure-resistant glass reactor equipped with a stirrer and an oil circulation heater, 3.0 g of magnesium dichloride, 16 ml of 2-ethylhexanol, and 15 ml of decane were charged under a nitrogen atmosphere, and stirred at 300 rpm at 80 ° C. The temperature was increased to 130 ° C. to completely dissolve the magnesium dichloride, and when a homogeneous solution was obtained, the reaction was maintained for 1 hour, and 0.2 ml of ethyl benzoate was added. After the addition, the temperature was maintained for 1 hour, and the temperature was lowered to room temperature to prepare a magnesium compound. A mixture of 31.4 ml of hexane and 16 ml of titanium tetrachloride was maintained at a temperature of -10 ° C., stirred at 600 rpm, and the magnesium compound was added for 1 hour. Upon completion of the addition, the temperature was increased to 70 ° C., maintained at the same temperature for 1 to 5 hours, and then lowered to 45 ° C., stirring was stopped, and the generated solid particles were precipitated. Afterwards, the supernatant was removed, washed five times with 2 liters of hexane, and dried to obtain a catalyst. Using the catalyst, polyethylene was produced in the same manner as in Example 1.

Comparative example 2: Production of catalyst and polyethylene

A catalyst was obtained in the same manner as in Comparative Example 1, except that hexane was not added. Polyethylene was produced using the catalyst in the same manner as in Example 1.

Comparative example 3: Production of catalysts and polyethylene

A catalyst was obtained in the same manner as in Example 1, except that 25 ml of hexane was added to the magnesium compound before adding titanium tetrachloride in Example 1. Using the catalyst, polyethylene was produced in the same manner as in Example 1.

Experimental example: Catalyst and measurement of properties of polypropylene

The properties of the catalysts and polypropylene manufactured in the above examples and comparative examples were measured using the following methods and are shown in Table 1.

The particle shapes of each catalyst and the manufactured polymer obtained in the above examples and comparative examples were observed using a scanning electron microscope (SEM), and the SEM images of the catalyst of Example 1 and the manufactured polymer are shown in FIGS. 1 and 2, respectively.

In addition, the particle size of the catalyst particles suspended in hexane was measured by a laser particle analyzer (Mastersizer X; manufactured by Malvern Instruments) via optical transmission. As a result, a cumulative particle size distribution was obtained, from which the average particle diameter and particle size distribution index were obtained as follows, and are listed in Table 1.

(1) Activity measurement: Measure the weight (kg) of polymer produced in 1 hour per weight (g) of catalyst used. That is, catalyst activity (kg-PE/g-Cat.) = polyethylene production amount (kg)/amount of catalyst (g).

(2) Apparent density measurement: According to ASTM D189, the polyethylene manufactured in a container with a volume of 100 cm ³ and a known weight is filled by free fall due to gravity, and the net weight is measured to obtain the apparent density. That is, the apparent density (g/cm ³ ) = net weight of polymer/100 ml.

(3) Average particle size ( _D50 ): The size of the particles corresponding to 50% of the cumulative weight.

(4) Particle size distribution index (P): P = (D ₉₀ -D ₁₀ )/D ₅₀

In the above, D ₉₀ is the particle size corresponding to 90% of the cumulative weight, and D ₁₀ is the particle size corresponding to 10% of the cumulative weight.

(5) Method for measuring average polymer particle size (APS) of polyethylene: The measurement of the APS (Average Particle Size) of polyethylene powder was performed by dropping 10 g of the sample on sieves consisting of 5, 10, 30, 45, 75, and 125 ㎛ using powder particle size analysis equipment Seishin RPS-105M, evenly dispersing the sample by vibration and hammering for 5 minutes, and then measuring the weight of the sample remaining in each sieve to calculate the average value.

division Catalyst average particle size (㎛) particle size distribution index Active
(kg-PE/g-Cat) Apparent density
(g/cm ³ ) Polymer average particle size (㎛) Example 1 0.8 0.2 43 0.35 27 Example 2 0.7 0.3 44 0.36 25 Example 3 0.9 0.3 39 0.34 28 Example 4 0.8 0.4 38 0.36 25 Example 5 0.9 0.5 39 0.37 26 Example 6 0.6 0.3 45 0.37 29 Example 7 0.9 0.4 32 0.30 32 Example 8 0.7 0.5 36 0.34 40 Example 9 0.9 0.4 35 0.36 42 Example 10 0.8 0.5 37 0.35 39 Example 11 0.7 0.5 39 0.37 44 Example 12 0.9 0.6 38 0.38 49 Example 13 0.8 0.5 40 0.38 45 Comparative Example 1 6.5 1.2 18 0.30 214 Comparative Example 2 7.1 1.1 16 0.29 223 Comparative Example 3 5.4 1.0 21 0.31 162

As shown in Table 1 above, it can be confirmed that the catalyst manufactured by adding a transition metal compound to a magnesium compound as in the present invention has excellent activity, a small catalyst particle size, and is capable of polymerizing polyethylene having a significantly small polymer particle size.

In particular, since the catalyst of the present invention can polymerize polyethylene having a small particle size suitable for product application and a narrow particle size distribution, it is possible to obtain polyethylene suitable for various product applications, such as membranes, additives, etc. for coating, lubrication, wear resistance, and chemical resistance purposes.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and it will be apparent to those skilled in the art that various modifications and variations are possible within a scope that does not depart from the technical spirit of the present invention described in the claims.

Claims (12)

A step of preparing a magnesium compound solution by dissolving the magnesium compound in a mixed solvent containing the hydrocarbon compound and the alcohol, wherein the alcohol is used in an amount of 3 to 4 moles per 1 mole of the magnesium compound and the hydrocarbon compound is used in an amount of 2 to 4 moles per 1 mole of the magnesium compound; and
A step of reacting by adding a transition metal compound that is not mixed with a non-polar solvent to the magnesium compound solution at a rate of 5 to 10 ml/hour;
A method for producing a catalyst for polyethylene polymerization, comprising:
In the first paragraph,
A method for producing a catalyst for polyethylene polymerization, wherein the hydrocarbon compound is a (C ₉ -C ₂₅ ) hydrocarbon.
In the first paragraph,
A method for producing a catalyst for polyethylene polymerization, wherein the hydrocarbon compound is at least one compound selected from the group consisting of decane, dodecane, tetradecane, cyclic hexane, cyclic octane, methyl cyclic pentane, methyl cyclic hexane, benzene, toluene, xylene, ethylbenzene, and cumene.
delete In the first paragraph,
A method for producing a catalyst for polyethylene polymerization, wherein the alcohol is at least one compound selected from the group consisting of aliphatic or alicyclic alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, n-pentanol, isopentanol, neopentanol, cyclopentanol, n-hexanol, n-heptanol, n-octanol, decanol, dodecanol, 2-methylpentanol, 2-ethylbutanol, 2-ethylhexanol; cyclohexanol, methylcyclohexanol, and α-methylbenzyl alcohol.
In the first paragraph,
A method for producing a catalyst for polyethylene polymerization, further comprising a step of introducing an internal electron donor into a magnesium compound solution and causing a reaction prior to the step of introducing the above transition metal compound and causing a reaction.
In Article 6,
Internal electron donors include ethyl benzoate, methyl benzoate, propyl benzoate, isopropyl benzoate, tibutyl benzoate, tibutyl 4-(2-aminoethyl) benzoate, ethyl 4-(dimethylamino) benzoate, ethyl 4-(butylamino) benzoate, ethyl 4-(bromomethyl) benzoate, ethyl 4-(benzyloxy) benzoate, methyl 4-(hydroxymethyl) benzoate, methyl 4-(aminomethyl) benzoate, methyl 3-(aminocarbonyl) benzoate, methyl 4-(2-hydroxyethoxy) benzoate, methyl 4-(cyanomethyl) benzoate, methyl 4-(bromomethyl) benzoate and methyl 3-(bromomethyl) Benzoate, 1,2-dimethoxybenzene, 1,2-diethoxybenzene, 1,2-dibuthoxybenzene, 1,2-di-sec-butoxybenzene, 1,2-di-tert-butoxybenzene, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, vinyltrimethoxysilane, methyltrimethoxysilane, n-propyltriethoxysilane, tetryltrimethoxysilane, cyclopentyltrimethoxysilane, 2-methylcyclophenyltrimethoxysilane, 2,3-dimethylcyclopentyltrimethoxysilane, phenyltrimethoxysilane, vinyltriethoxysilane, t-butyltriethoxysilane, n-butyltriethoxysilane, A method for producing a catalyst for polyethylene polymerization, said catalyst comprising at least one compound selected from the group consisting of iso-butyltriethoxysilane, decyltriethoxysilane, cyclopentyltriethoxysilane, cyclohexyltriethoxysilane, chlorotriethoxysilane, ethyltriisopropoxysilane, vinyltributoxysilane, trimethylphenoxysilane, methyltriallyloxysilane, vinyltriacetoxysilane, dimethylmethoxysilane, diisopropyldimethoxysilane, t-butylmethyldimethoxysilane, dicyclopentyldimethoxysilane, dicyclohexyldimethoxysilane, cyclohexylmethyldimethoxysilane, diphenyldimethoxysilane, and cyclopentyldimethyloxysilane.
In Article 6,
A method for producing a catalyst for polyethylene polymerization, wherein the reaction molar ratio of the magnesium compound and the internal electron donor compound in the step of mixing and reacting the internal electron donor compound is 1:0.01 to 1:1.
In the first paragraph,
The above transition metal compound is a method for producing a catalyst for polyethylene polymerization, comprising a compound of the following chemical formula 1:
[Chemical Formula 1]
MX _n (OR ¹ ) _4-n
(In the above chemical formula 1, M is selected from the group consisting of transition metal elements of groups IVB, VB and VIB of the periodic table,
X is a halogen,
R ¹ is a (C ₁ -C ₁₀ ) alkyl group,
n is 0 to 4.)
In the first paragraph,
A method for producing a catalyst for polyethylene polymerization, further comprising a step of reacting a catalyst with an alkyl aluminum compound represented by the following chemical formula 2:
[Chemical formula 2]
AlR ² _m X _3-m
(In chemical formula 2,
R ² is a (C ₁ -C ₈ ) alkyl group,
X is a halogen,
m is 0 to 3.)
delete A method for producing polyethylene, comprising the step of polymerizing or copolymerizing an ethylene monomer in the presence of a catalyst for polyethylene polymerization prepared according to any one of claims 1 to 3 and claims 5 to 10.

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