KR19990010007A - Ethylene Polymerization Catalyst - Google Patents

Abstract

The present invention relates to a catalyst used in the preparation of an ethylene polymer having high activity and having a granular particle shape and a uniform particle size distribution by using an ether compound during recrystallization during the preparation of the catalyst.

Description

Ethylene Polymerization Catalyst

The present invention relates to a catalyst exhibiting high activity and having a narrow molecular weight distribution and having excellent physical properties.

Conventional olefin polymerization catalysts are prepared by contacting a magnesium compound having a bivalent magnesium compound with an alcohol, an organic carboxylic acid, an aldehyde, an amine, and a mixture thereof in an inert hydrocarbon solvent to a halogen-containing titanium compound. By reaction to prepare a solid catalyst component or to produce an active carrier using a halogen-containing silicon compound, tin compound or aluminum compound as a recrystallized compound and then contacting with a titanium halide compound to prepare a solid titanium catalyst component. .

In U.S. Patent Nos. 3,642,746, 4,336,360 and 4,330,649, to prepare a highly active catalyst, a magnesium carrier is reacted with an electron donor such as alcohol in a hydrocarbon solvent to make it in a liquid state, followed by reaction with a halogen compound such as silicon tetrachloride. To form a solid magnesium carrier and carry a titanium compound such as titanium tetrachloride to prepare a catalyst for polymerization, or to directly recrystallize by adding titanium tetrachloride. A method for preparing a catalyst for polymerization is described.

In addition, efforts have been made to control the activity and molecular weight distribution of olefin polymerization by adding secondary electron donors such as esters to the liquid magnesium solution. However, these catalysts are known to exhibit high activity but have a disadvantage in that deactivation of the catalyst proceeds rapidly during polymerization at high temperatures. In addition, the particle shape of the polymer polymerized using such a catalyst is granular, but because of its rough shape, the flowability is poor, the apparent density of the polymer is low, the particle size of the polymer is small, and the particle size distribution is considerably wide. Therefore, the amount of fine particles produced increases and the amount of polymer dissolved in hexane increases in hexane slurry polymerization.

It is an object of the present invention to compensate for the disadvantages of the conventional catalyst as described above, while exhibiting high activity and inactivation does not proceed at a high temperature, and provides a catalyst that is used for the preparation of an ethylene polymer having a granular particle shape and a uniform particle size distribution. It is.

That is, in the present invention, by reducing the reactivity of the recrystallized compounds titanium halide, silicon halide, aluminum compound with alcohol by using an ether compound, which is a Lewis base containing oxygen, by controlling the shape of the resulting carrier polymer of the polymer It provides a catalyst that polymerizes polymers having a granular shape and a smooth shape to polymerize polymers having high apparent density, low amount of fine particles and good flowability.

The present invention is described in more detail as follows.

In the catalyst of the present invention, a magnesium compound and an alcohol are brought into contact with each other in a hydrocarbon solvent to form a liquid magnesium compound, and then two electron donors of an ester compound containing a hydroxy group and a silicon compound having an alcohol group are reacted with the liquid magnesium compound. Alternatively, a magnesium compound, an alcohol, and the two electron donors are brought into contact with each other in a hydrocarbon solvent to form a liquid magnesium compound in which the electron donor is dissolved, and then, a titanium compound is added to the reaction and recrystallized.

Various hydrocarbon solvents are used as solvents for the preparation of liquid magnesium compounds, for example aliphatic hydrocarbons such as hexane, heptane, octane, decane and kerosine or alicyclic hydrocarbons such as cyclohexane and cyclooctane, benzene Aromatic hydrocarbons such as toluene, xylene, ethylbenzene and the like can be used. The amount of hydrocarbon solvent to be used is preferably in the form of a solution of preferably 0.1 to 5 mol, more preferably 0.3 to 3 mol based on the amount of magnesium. Since the amount of the solvent varies depending on the preparation conditions and the preparation method of the catalyst, it should be determined in consideration of economical efficiency and ease of preparation of the catalyst.

Examples of the alcohols used to form the liquid magnesium compound include aliphatic alcohols such as methanol, ethanol, butanol, isopropanol, hexanol, 2-ethylhexanol and decanol, cyclic alcohols such as cyclohexanol and benzene alcohol, Aromatic alcohol etc. are mentioned. The amount of alcohol used is preferably 0.1 to 10 moles per mole of magnesium. Although there is no upper limit to the amount of alcohol, it is preferable not to use too much economically, so it is most appropriate to use 3 to 6 moles of alcohol in consideration of enhancement of activity and economical efficiency. In particular, in order to form a uniform liquid magnesium compound, the amount of alcohol used is most preferably about 3 to 4 moles. The contact temperature of the magnesium compound and the alcohol generally depends on the room temperature or higher and the form of the compound, but the reaction is preferably performed at a temperature of about 80 to 220 ° C, more preferably about 90 to 150 ° C for about 30 minutes to 2 hours. Do this.

Since the reaction temperature and reaction time of the magnesium compound and the alcohol vary depending on the molar ratio of the magnesium compound and the alcohol, and the amount of the solvent used for the magnesium compound, it is desirable to have an optimum condition with proper arrangement of the constituent materials.

Among the electron donors used in the present invention, ester compounds containing hydroxy groups include hydroxy groups such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, pentaerythritol triacrylate, and the like. Unsaturated fatty acid esters containing, 2-hydroxyethyl acetate, methyl or ethyl 3-hydroxybutylate, methyl or ethyl 2-hydroxyisobutylate, methyl-3-hydroxy-2-methylpropionate, 2 , 2-dimethyl-3-hydroxypropionate, ethyl-6-hydroxyhexanoate, t-butyl-2-hydroxyisobutylate, diethyl-3-hydroxyglutarate, ethyl lactate, Isopropyl lactate, butyl or isobutyl lactate, ethyl mandelate, dimethyl or diethyl tartrate, dibutyl tartrate, diethyl citrate, triethyl citrate, ethyl Aliphatic monoesters and polyesters such as 2-hydroxycaproate, diethylbis (hydroxymethyl) malonate, etc., 2-hydroxyethyl benzoate, 2-hydroxyethyl sillylate, methyl 4- (hydroxy Such as methyl) benzoate, methyl 4-hydroxybenzoate, ethyl 3- or 4-hydroxybenzoate, methyl, ethyl or phenylsilicate, propyl 4-hydroxybenzoate, phenyl 3-hydroxynaphthanoate, and the like. Aromatic esters, cyclic esters such as hydroxybutyrolactone and the like can be used.

Among the electron donors used in the present invention, silicon compounds having an alkoxy group include R _n Si (OR) _4-n (where R is a hydrocarbon having 1 to 6 carbon atoms and n is a natural number of 0 to 4). Compounds having a structure are preferred, but more preferably compounds containing at least two alkoxy groups are preferred. Specifically, dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, methylphenyldimethoxysilane, diphenyldiethoxysilane, ethyltrimethoxysilane, vinyltrimethoxysilane, methyltrimethoxysilane, phenyl Trimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, vinyltriethoxysilane, butyltriethoxysilane, phenyltriethoxysilane, ethyltriisopropoxysilane, vinyltributoxysilane, ethylsilicate The use of compounds, such as butyl silicate and methyltriaryloxysilane, is preferable.

These electron donors may be used together with the alcohol used to form the liquid magnesium compound, or may be added after forming the liquid magnesium. The reaction between the two complementary electron donors of the ester compound containing a hydroxy group and the silane compound containing an alkoxy group and the liquid magnesium compound is carried out at room temperature to 130 ° C, and the reaction time is preferably performed for about 30 minutes to 2 hours. . The amount of ester compound comprising a hydroxy group can be appropriately changed, for example 0.01 to 5 moles, more preferably 0.05 to about 1 mole per mole of magnesium is suitable. If the amount of the ester compound containing a hydroxy group is too large, it may be deposited on the solid product too much and may have an adverse effect depending on the form of the electron donor. In addition, the amount of the silane compound having an alkoxy group may also be appropriately changed, for example, 0.5 to about 1 mole per mole of magnesium is suitable. If the amount of the silane compound having an alkoxy group is too large, there is an adverse effect that the activity of polymerization is sharply reduced.

The solid titanium component is prepared by directly adding an excess of a liquid titanium compound in a state in which the liquid magnesium compound and the two complementary electron donors are uniformly dissolved. At this time, the titanium compound is slowly added dropwise at 0 ℃ to room temperature to increase the temperature to perform the reaction, the reaction temperature is preferably carried out at 40 ~ 130 ℃, more preferably 50 ~ 110 ℃ reaction time is It is preferable to carry out as about 30 to 4 hours.

The solid titanium component obtained above is dissolved in alcohol and recrystallized from titanium halide, silicon halide, aluminum compound or the like to produce solid catalyst particles. At this time, although the shape of the solid catalyst particles may be smoothed by lowering the temperature of recrystallization, in the present invention, ethers, which are Lewis bases containing oxygen, may be used to reduce the reactivity of titanium halides, silicon halides, aluminum compounds, etc. with alcohol To reshape the solid catalyst particles. The ether used in the present invention is one selected from aliphatic ethers such as diethyl ether, dibutyl ether, isoamyl ether, isopropyl ether, diphenyl ether, ethyl butyl ether, and alicyclic ethers such as tetrahydrofuran, dioxin and the like. It indicates the above. Among these, alicyclic ethers such as tetrahydrofuran, dioxin and the like reduce the reactivity of the titanium halides, silicon halides, and aluminum compounds with alcohol to smooth the shape of the solid catalyst particles.

The catalyst thus prepared is washed with purified hexane or heptane until free titanium is not detected, dried, and placed in a nitrogen atmosphere for use in the polymerization reaction.

The titanium compound, which is an active ingredient of the catalyst obtained by the above method, exists as a compound in which a silane compound having an alkoxy group is coordinated to a compound in which hydrogen is released from the active hydrogen of the hydroxy group by reacting with the liquid titanium compound. In general, it can be expressed as (ExED) Ti (OR) _m (ED) _n X _4-mn . Wherein R is a hydrocarbon group, x is a halogen atom, ED is a compound in which the hydrogen of the hydroxy group is released from an ester compound containing a hydroxy group, and ExED is a silane compound including a coordinated alkoxy group , m, n are natural numbers less than 4.

The ester-based electron donor has a disadvantage of being temporarily separated from the surface of the titanium metal by a reducing organometallic aluminum compound, which is a cocatalyst used in the polymerization reaction. Although there is a tendency to inhibit the physical properties of the present invention, according to the present invention, by using an ester compound having a hydroxy group and a silane compound having an alkoxy group as an electron donor, the ester compound having a hydroxy group acts as a primary electron donor to react with a promoter This prevents it from being separated from the titanium metal active point at one time. In addition, when the ester compound having a hydroxy group is separated from the active point of the titanium metal, the silane compound having an alkoxy group acts as a secondary electron donor to protect the active point. Separation prevents rapid deactivation. Actually, the silane compound having an alkoxy group has excellent pi electron donating ability and thus is used very effectively in the present invention.

The present invention will be described in detail through the following examples.

Example 1

Preparation of the catalyst

9.5 g of commercially available anhydrous magnesium chloride was suspended in 150 ml of toluene purified under a nitrogen stream, and 62 ml of 2-ethylhexyl alcohol (4 mol per mol of magnesium chloride) were added. The mixture was slowly heated while stirring to react at 130 ° C. for 1 hour, thereby preparing a colorless transparent solution completely free of solids. This solution was cooled to room temperature to obtain a magnesium chloride / 2-ethylhexyl alcohol complex in a toluene solution. 1.2 ml of 2-hydroxyethyl methacrylate (0.1 mol per mol of magnesium chloride) and 20 ml of tetrahydrofuran were added to the solution, and the mixture was heated to 70 ° C and maintained for 1 hour. The solution was cooled to 30 ° C, 10 ml (45 mmol) of silicon tetraethoxide was injected, and 30 ml (0.274 mol) of titanium tetrachloride was added dropwise for 1 hour. When the dropping is completed, the temperature is raised to 80 ° C. over 1 hour and maintained for 1 hour. After the reaction was washed with hexane to obtain a solid catalyst. Catalyst composition was 3.4 weight% titanium, 57 weight% chlorine, and 17 weight% magnesium.

Polymerization

Into a 2-liter autoclave, 1 liter of purified hexane was injected. In a nitrogen atmosphere, 3.0 mmol of triethylaluminum and 0.03 mmol of a titanium atom were injected into an autoclave in a nitrogen atmosphere. The polymerization was carried out for 2 hours at atmospheric pressure.

After the completion of the polymerization, 250 g of white powder was obtained. The activity of the catalyst was 8.3 kg-PE / mmol-Ti, the volume density was 0.32, the melt index was 8.7, and the particle size distribution was as follows.

Claims (2)

In the catalyst for ethylene polymerization prepared by adding, reacting and recrystallizing an electron donor and a titanium compound to a liquid magnesium compound, A catalyst for ethylene polymerization, which is prepared by using an ether compound at the time of recrystallization. The method of claim 1, The ether compound is at least one selected from aliphatic ethers such as diethyl ether, dibutyl ether, isoamyl ether, isopropyl ether, diphenyl ether and ethyl butyl ether, and alicyclic ethers such as tetrahydrofuran and dioxin. Catalyst for ethylene polymerization.