KR0139882B1 - Catalyst for ethylene polymerization and its processing method - Google Patents

Abstract

The present invention relates to a catalyst for ethylene polymerization and a method for preparing the same, wherein at least one of transition metal compounds, at least one of main group metal halides, at least one of hydroxides of main group metals, and at least one of alkyl halide aluminum or boron compounds After completely dissolving in a solvent to prepare a solution, an inert inorganic oxide support is injected into the solution, and an aluminum compound is used as a promoter to dry with good flow to prepare a catalyst for ethylene polymerization.

Description

Ethylene Polymerization Catalyst and Method for Preparing the Same

The present invention relates to a catalyst for ethylene polymerization and a method for preparing the same, and more particularly, to a catalyst for ethylene polymerization and a method for preparing the ethylene polymer having a wide molecular weight distribution with a high activity Ziegler-Natta catalyst.

Hereinafter, the polymer in the present invention shall include a homopolymer of ethylene or a copolymer with an α-olefin.

Control of molecular weight distribution in olefin polymerization by Ziegler-Natta catalysts is known to be possible through changes in catalysts, cocatalysts, polymerization processes and polymerization factors.

In preparing ethylene polymer, U. S. Patent No. 219, 877 dissolves MgCl ₃ , TiCl ₃ .1 / 3AlCl ₃ in tetrahydrofuran and then supports it on silica surface-treated with alkylaluminum to prepare a catalyst precursor, followed by a boron halide compound. And a method of partially activating an alkylaluminum to produce an ethylene polymer. The resin polymerized using such a catalyst has a melt flow rate of about 24 to 32 in a density range of 0.94 to 0.97 g / cm ³ , and has a resin having such physical properties. Is a resin called high-density polyethylene, but the strength after processing is good, but the melt flow rate ratio is low, there is a disadvantage in poor workability. In order to solve such processing disadvantages, when a resin having a high melt flow rate ratio is to be prepared, a polymerization process using several steps or a method of blending resins having different molecular weights are used. It is necessary to have a complex device or to prepare resins having different molecular weights, and thus, when blending, advanced techniques are required in controlling the molecular weight and blending ratio.

Therefore, it can be said that the preferred direction is to control the molecular weight distribution by changing the polymerization catalyst system rather than the above method.

For this reason, Korean Patent Publication No. 94-0410 has a composition similar to that of the previous patent, but increases the amount of boron halide to increase the activity of the catalyst, and has a density of 0.91 to 0.97 g / cm ³ and a melt flow rate of 32 to 40. Phosphorus resin was prepared to solve the processing problem, but the resulting resin has a lot of fine particles and a large amount of boron halide has a disadvantage.

On the other hand, US Patent No. 3,644,318 discloses a method for controlling the molecular weight distribution by changing the Mg compound, the invention can control the molecular weight distribution extensively, but the activity is very low. Another U.S. Patent No. 4,128,502 discloses a method of controlling the molecular weight distribution by changing the Mg compound and also changing the Ti compound, but there is also a problem in that the activity is not high. The catalysts described in the two patents (US Pat. Nos. 3,644,318 and 4,128,502) have not only low activity but also have the disadvantage of not controlling the shape of the resulting resin.

Accordingly, an object of the present invention is to compensate for the disadvantages of the above patents to exhibit high activity in slurry or gas phase polymerization reactions, to have a high melt flow rate ratio, less halogen-containing compounds, and a catalyst for producing ethylene polymer resin having excellent shape. And to provide a method for producing the same.

In order to achieve the above object, the catalyst according to the present invention includes at least one of transition metal compounds, at least one of magnesium halide compounds, at least one of hydroxides of group IIA on the periodic table, and at least one of alkyl halide aluminum and boron compounds. After completely dissolving in a solvent to prepare a solution, an inert inorganic oxide support is injected into the solution, and prepared by drying with good flowability in a temperature range of 40 to 140 ° C. using an aluminum compound as a promoter.

Looking at the present invention in more detail as follows.

In the method for producing a catalyst according to the present invention, as the tri or tetravalent transition metal compound, a compound represented by TiCl ₃ .1 / 3AlCl ₃ or the following general formula (I) is used.

Wherein X is halogen, R is C1-15 aliphatic or aromatic hydrocarbon, p is an integer from 0 to 4.

As the halogen compound of divalent magnesium, a compound represented by the following general formula (II) or (III) is used, and MgCl ₂ is most preferable.

Wherein X is halogen, R is an aliphatic or aromatic hydrocarbon having 1 to 10 carbon atoms, q is an integer from 0 to 2.

The molar ratio of Ti / Mg is from 0.1 to 20, preferably from 0.5 to 5.

If the Ti / Mg molar ratio is out of the above range, the activity and melt index are very low.

Examples of hydroxides of group IIA on the periodic table include Mg (OR) ₂ , Mn (OH) ₂ , Zn (OH) ₂ , or Ca (OH) _2, and are used in a Ti / Mg (OH) ₂ molar ratio of 0.1 to 20. . If the Ti / Mg (OH) ₂ molar ratio is out of this range, the active and melt flow rate ratios decrease.

The alkylhalogen aluminum compound is a compound represented by the following general formula (IV),

Wherein R is an aliphatic hydrocarbon or hydride radical having 1 to 8 carbon atoms, X is halogen, and r is an integer from 0 to 3.

The Al / Ti molar ratio is used in the range of 0.1 to 50, preferably 0.3 to 5. If the Al / Ti molar ratio is out of the above range, the melt flow rate ratio decreases.

Boron compound according to the invention is represented by the following general formula (V)

Wherein X is halogen, R is an aliphatic or aromatic hydrocarbon having 1 to 10 carbon atoms, and s is an integer from 0 to 3.

The Al / Ti molar ratio is used in the range of 1 to 30 when using the aluminum compound, and the B / Ti molar ratio is used in the range of 0.1 to 30 when using the boron compound. As the organic electron donor solvent, ether, phosphine, ketone, aldehyde, ester, tetrahydrofuran, acetone or nitrile having 2 to 20 carbon atoms is used alone or in combination.

As the cocatalyst in the present invention, an aluminum compound represented by the general formula (IV) is used, wherein R, r and X are as described above and used as the compound alone or as a mixture.

The inorganic oxide support is silica surface-treated with trialkyl aluminum (where the alkyl group is an aliphatic hydrocarbon having 1 to 8 carbon atoms), and is used in a range of 20 to 100 times based on the Ti atom weight.

The inorganic oxide support is used to be 0.01g to 0.5g, preferably 0.05g to 0.3g per 10g of the inorganic oxide support. The drying temperature is preferably 60 to 100 ° C.

The catalyst obtained by the above method is used for the production of ethylene homopolymers or copolymers of ethylene and alpha olefins in the absence of catalyst poisons such as water, oxygen, carbon monoxide, carbon dioxide and acetylene. In the present invention, the alpha olefins are ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, and 1-octene, and the like, the catalyst composition prepared in advance and the pressure of 1500psi or less, 40 to 120 Under a temperature of < RTI ID = 0.0 > C, < / RTI > and suitable hydrogen, hydrocarbons such as normal hexane, heptane, octane and the like are polymerized into a slurry or gas phase polymerization without solvent.

The effect of the present invention is that the polymerization activity of ethylene or ethylene and alpha olefins per gram of the prepared catalyst, in particular per gram of the transition metal is sufficiently high, and does not undergo deliming (removal of the remaining catalyst of the ethylene polymer) because it does not use an excess of halogen compounds. Even if there is no pigmentation of the polymer, there is no damage to the physical properties or rust in the mold when the polymer is molded. In addition, since the Ti content supported on the inorganic oxide has a low weight% from 0.1% to 5% and the activity is moderately high, it has a significant advantage as a catalyst for gas phase polymerization (if the Ti content is too high, the reaction control during gas phase polymerization is Difficult and easy to produce fine powder), since no by-products are produced during the production of the catalyst, there is no need for a facility for treating the by-products, and the production process of the catalyst is simple and commercially applicable.

The density of the resin polymerized using the catalyst according to the invention ranges from 0.92 g / cm 3 to 0.97 g / cm 3. The density of the polymer at a given melt index is controlled primarily by the amount of comonomer copolymerized with ethylene. Polymerization with ethylene alone yields a resin having a density of at least 0.96 g / cm 3 or more, and a copolymer having a lower density is obtained as the amount of comonomer is increased. The molecular weight can be determined from the melt index of the ethylene homopolymer or copolymer, i.e., the higher the molecular weight of the polymer, the lower the melt index.

The polymer prepared using the catalyst prepared according to the present invention has a standard or normal load melt index (measured at 190 ° C. by MI, ASTM D-1238 (E) and the unit is g / 10 min.) 0.08 g / 10min to 30g / 10min, preferably 0.3g / 10min to 15g / 10min, high load melt index (or flow index (HLMI), measured according to ASTM D-1238 (F) and measured melt index The weight is measured at 10 times the weight used in the range of 2.0g / 10 minutes to 1350g / 10 minutes. The melt index increases as the polymerization temperature increases or the amount of hydrogen added increases and increases even when the polymer density decreases. The melt flow rate ratio, on the other hand, is one measure of the molecular weight distribution (Mw / Mn) of the polymer.

The ethylene polymer prepared using the catalyst according to the present invention has a melt flow rate ratio (MFR = flow index / melt index and flow index according to ASTM D-1238 (F)) of about 26 to 45, preferably 30 to 43. . Therefore, as described above, the ethylene homopolymer or ethylene copolymer with high strength can be produced by slurry reaction or gas phase reaction without wider molecular weight distribution and processing problems.

Another effect of the present invention is that the shape of the ethylene polymerized particles is very good. If the polymer particle shape is bad, problems per volume of the polymerization reactor, production efficiency per hour, pipe transport of the polymer are likely to occur, and adversely affect the assembly of the polymer powder. The good shape of the polymer particles referred to herein means that the polymer particles are spherical or close to spherical and the surface of the particles is lubricated. Poor polymer shape refers to a state in which the polymer particles are not spherical, irregularities are remarkable, and the surface is not lubricated. Good and bad polymer shape is determined by measuring the specific gravity of the polymer powder (ASTM D-1895 Method B, the resin is placed in a 400 ml graduated cylinder without shaking through a 3/8 inch diameter funnel and weighed). It is possible that the specific gravity is preferably 0.3 or more. The volume specific gravity of the polymer obtained by the present invention has a high value of 0.31 to 0.39, the particles are spherical or close in shape, and the particle surface is smooth.

Hereinafter, the present invention will be described in more detail with reference to the following examples, which are intended to illustrate the method of the present invention, but do not limit the scope of the present invention. The properties of the polymers prepared in the examples are measured by the test method as described above.

Example 1

In a 1 L three-necked flask equipped with a circulating cooling device and a mechanical stirrer, 2.4 g of anhydrous MgCl (0.025 mol) and 1.5 g of anhydrous Mg (OH) ₂ (0.025 mol) were placed in 500 ml of tetrahydrofuran, followed by To the solution were added 0.03 moles of EtAlCl ₂ and 0.02 moles TiCl ₄ , respectively, over 1 hour. This solution is dissolved by vigorous stirring at 60 ° C. for 12 hours. After confirming that the solid was completely dissolved, 50 g of silica dehydrated at 700 ° C. and surface treated with 5% by weight of triethylaluminum was added to the solution. The slurry solution is stirred for about 3 hours and then dried under nitrogen at 60 ° C. until a solid product (I) with good flowability is obtained. The titanium atom content in the solid product (I) was 10 mg (titanium atom) / g (solid product (I)).

Example 2

After replacing a 2 L stainless reactor with a volume of nitrogen, 0.8 L of normal heptane, 0.001 mol of triethylaluminum, and 0.12 g of solid product (I) of Example 1 were added to seal the reactor, and a nitrogen gauge pressure of 2 kg / Up to cm ² G, up to 4 kg / cm ² G of hydrogen gauge pressure, up to 10 kg / cm ² G of ethylene gauge pressure, the polymerization reaction was carried out at a polymerization temperature of 90 ° C. for 2 hours. After the completion of the reaction, the slurry containing the ethylene polymer was filtered and dried without deliming to obtain 250 g of a white polymer. The recovery of polymer per gram of solid product (I) is 2083 grams, and the polymer yield per gram of titanium atoms is 2.08 x 10 ⁵ grams, so the catalytic efficiency per titanium atom is quite high. The obtained polymer had a volume specific gravity of 0.4, was spherical in shape, and the deliming step was omitted, but there was almost no coloring of the polymer. The physical properties of this polymer were measured, and the results are shown in Table 1 below.

Example 3

Instead of EtAlCl ₂ used in Example 1 was reacted with 200 mmol of BBr ₃ in a normal hexane solvent to give a solid product (II), and the catalyst was polymerized in the same manner as in Example 2 to obtain 203 g of a white polymer. The polymer recovery amount per 1 g of solid product (II) was 1692 g, and the polymer yield per 1.7 g of titanium atom was 1.7 × 10 ⁵ g. The physical properties of this polymer were measured, and the results are shown in Table 1 below.

Example 4

Instead of EtAlCl ₂ used in Example 1 was reacted with 7 mmol of trihexyl aluminum in a normal hexane solvent to give a solid product (III), and the catalyst was polymerized in the same manner as in Example 2 to obtain 290 g of a white polymer. The polymer recovery amount per 1 g of solid product (III) was 2417 g, and the polymer yield per g of titanium atom was 2.21 x 10 ⁵ g. The physical properties of this polymer were measured, and the results are shown in Table 1 below.

Example 5

Instead of EtAlCl ₂ used in Example 1 was reacted with 7mmol of trihexyl aluminum in a normal hexane solvent and then 20mmol of BBr ₃ to obtain a solid product (IV), and the catalyst was polymerized in the same manner as in Example 2 to 265g of white A polymer was obtained. The polymer recovery amount per gram of solid product (IV) was 2208 g, and the polymer yield per gram of titanium atom was 2.21 x 10 ⁵ g. The physical properties of this polymer were measured, and the results are shown in Table 1 below.

Example 6

In Example 1, the silica was treated with 3.5% by weight, and EtAlCl ₂ was the same as Example 1 except that 0.05 mole was used. The solid product (V) thus obtained was polymerized in the same manner as in Example 2 to obtain 215 g of a white polymer. The physical properties of this polymer were measured, and the results are shown in Table 1 below.

Example 7

Example 1 was the same as in Example 1 except that the silica was treated by 3.5% by weight. The solid product (VI) thus obtained was polymerized in the same manner as in Example 2 to obtain 130 g of a white polymer. The physical properties of this polymer were measured, and the results are shown in Table 1 below.

Example 8

Example 1 was the same as in Example 1 except for replacing EtAlCl ₂ with AlEt ₃ . The solid product thus obtained was polymerized in the same manner as in Example 2 to obtain 250 g of a white polymer. The physical properties of this polymer were measured, and the results are shown in Table 1 below.

Example 9

Example 1 was the same as in Example 1 except for replacing EtAlCl ₂ with AlEt ₃ . The solid product thus obtained was polymerized in the same manner as in Example 2 to obtain 255 g of a white polymer. The physical properties of this polymer were measured, and the results are shown in Table 1 below.

Comparative Example 1

Example 1 was the same as in Example 1 except for replacing EtAlCl ₂ with SiCl ₄ . The solid product thus obtained was polymerized in the same manner as in Example 2 to obtain 650 g of a white polymer. The physical properties of this polymer were measured, and the results are shown in Table 1 below.

Comparative Example 2

Example 1 was carried out in the same manner as in Example 1 except that only 4.8 g of anhydrous MgCl ₂ (0.05 mol) was used, and anhydrous Mg (OH) ₃ and EtAlCl ₃ were not used. The solid product (X) thus obtained was polymerized in the same manner as in Example 2 to obtain 275 g of a white polymer. The polymer recovery amount per gram of solid product (X) was 2292 g, and the polymer yield per gram of titanium atom was 2.29 x 10 ⁵ g. The physical properties of this polymer were measured, and the results are shown in Table 1 below.

Comparative Example 3

Example 1 was carried out in the same manner as in Example 1 except that only 4.8 g of anhydrous MgCl ₂ (0.05 mol) was used, and anhydrous Mg (OH) ₂ was not used. The solid product (XI) thus obtained was polymerized in the same manner as in Example 2 to obtain 600 g of a white polymer.

The amount of polymer recovered per 1 g of solid product (XI) was 5000 g, and the amount of polymer per 1 g of titanium atom was 5.0 × 10 ⁶ g, so the catalytic efficiency per titanium atom was higher than that in Example 1. The physical properties of this polymer were measured, and the results are shown in Table 1 below.

[Comparative Example 4]

EtAlCl ₂ was carried out in the same manner as in Example 1 except that it was not used. The solid product (XII) thus obtained was polymerized in the same manner as in Example 2 to obtain only a small amount of polymer. The physical properties of this polymer were measured, and the results are shown in Table 1 below.

Activity = g mmole Ti ^-1 h ^{-1 100} psig ^-1

Melt Index = g / 10min

Volume specific gravity = g / cm ³

As can be seen in Table 1, the product produced using the catalyst according to the present invention can be seen that the properties are excellent in the melt index, melt flow rate ratio and volume ratio compared to the product prepared by the conventional method. .

Claims (6)

In the method for producing a catalyst for ethylene polymerization, At least one of a transition metal compound represented by TiCl ₃ 1/3 AlCl ₃ or the following general formula (I), and at least one of a magnesium compound represented by the following general formula (II) or the following general formula (III), IIA on the periodic table At least one of Mg (OH) ₂ or Zn (OH) _{2 which} is a hydroxide of a group, and at least one of an aluminum compound represented by the following general formula (IV) or a boron compound represented by the following general formula (V) A method for producing an ethylene polymerization catalyst, characterized in that the donor is used as a solvent and supported on an inert inorganic oxide support, followed by drying. Wherein X is halogen, R is C1-15 aliphatic or aromatic hydrocarbon, p is an integer from 0 to 4. Wherein X is a halogen, R is an aliphatic or aromatic hydrocarbon having 1 to 10 carbon atoms, and q is an integer from 0 to 2. Wherein R is an aliphatic or aromatic hydrocarbon having 1 to 10 carbon atoms. Wherein each R is an alkyl or hydride radical, X is halogen and r is an integer from 0 to 3. Wherein X is halogen, R is an aliphatic or aromatic hydrocarbon having 1 to 10 carbon atoms, and s is an integer from 0 to 3. The method of claim 1, wherein the Ti / Mg molar ratio is in the range of 0.1 to 20, and the Ti / Mg (OH) ₂ molar ratio is used in the range of 0.1 to 20. The preparation of the catalyst for ethylene polymerization according to claim 1, wherein the organic electron donor is used alone or in combination of ether, phosphine, ketone, aldehyde, ester, tetrahydrofuran, acetone, or nitrile having 2 to 20 carbon atoms. Way. The method of claim 1, wherein the inorganic oxide support is characterized by using a silica surface-treated with trialkyl aluminum (where the alkyl group is an aliphatic hydrocarbon having 1 to 8 carbon atoms) in a range of 20 to 100 times based on the Ti atom weight. A method for producing a catalyst for ethylene polymerization. The method of claim 1, wherein the aluminum compound has an Al / Ti molar ratio of 1 to 30, and the boron compound has a B / Ti molar ratio of 0.1 to 30. Catalyst for ethylene polymerization prepared according to the method of claim 1.