CN102838702A - Catalyst for ethylene and alpha-olefin copolymerization and preparation method thereof - Google Patents

Abstract

The invention relates to a catalyst for copolymerization of ethylene and alpha-olefin and a preparation method thereof. The catalyst includes a magnesium compound, a titanium compound, an electron donor I and an electron donor II; wherein, the electron donor I is an ester compound; and the electron donor II is a siloxane compound. The preparation method of the catalyst is as follows: dissolve the magnesium compound in a hydrocarbon solvent and an alcohol solvent, and react at 70-90° C. for 2-4 hours; add electron donor I to react for 0.5-2 hours, and then add electron donor II to react for 0.5-2 hours; Add titanium compound dropwise at room temperature, react at 70-90°C for 1-3 hours; remove solvent, add hydrocarbon solvent, electron donor II to react for 1-2 hours, then add electron donor I to react for 1-2 hours; add titanium compound to react for 1-2 hours 3 hours; filtered, washed and dried to obtain the catalyst. The catalyst has high catalytic activity for catalyzing the copolymerization of ethylene and long-chain α-olefin, so that the long-chain α-olefin insertion rate of the prepared copolymer is high.

Description

Catalyst for copolymerization of ethylene and α-olefin and preparation method thereof

technical field

The present invention relates to a catalyst for the copolymerization of ethylene and alpha-olefins and a preparation method thereof, in particular to an electron donor-modified Ziegler-Natta catalyst for the copolymerization of ethylene and long-chain alpha-olefins and a preparation method thereof, The invention belongs to the field of olefin polymerization catalysts.

Background technique

Linear low-density polyethylene (LLDPE) is a copolymer of ethylene and α-olefins (ethylene and 1-butene, ethylene and 4-methyl-1-pentene) successfully developed in the 1970s, and its molecules have a linear structure , with a density of 0.91-0.94g/cm ³ , which is similar to LDPE produced by the high-pressure method, and is called the third-generation product of polyethylene. After the introduction of α-olefin monomers into the polymer, the resulting macromolecules contain a considerable amount of branched chains. These short-chained and long-chained branches will affect their physical properties. By adjusting the length of the branched chain, the degree of branching and the copolymerization monomer content, etc. to prepare the desired product. LLDPE combines many advantages of low-density polyethylene and high-density polyethylene, so it has low-temperature toughness, high modulus, bending resistance, puncture resistance, and tear resistance, and is widely used in films, pipes and other fields.

Ziegler-Natta catalyst plays an important role in the production of polyethylene because of its high catalytic efficiency, good overall performance of the produced polymer and low cost. Ziegler-Natta catalyst can not only catalyze the homopolymerization of ethylene and propylene, but also catalyze the copolymerization of ethylene and α-olefin (such as 1-butene, propylene) to prepare linear low density polyethylene (LLDPE).

The development of LLDPE represented a major change in polyethylene catalyst and process technology, and the range of polyethylene products was significantly expanded. However, the production of long-chain branched LLDPE requires a catalyst system with high activity and good copolymerization performance, while the traditional Ziegler-Natta catalyst is effective in catalyzing ethylene and long-chain α-olefins (such as 1-hexene, 1-octene, 1-decane When polymerized, the insertion rate of long-chain α-olefin is low, and the synthesized ethylene copolymer has a wide composition distribution; this chain structure feature has an adverse effect on many properties of LLDPE, resulting in film transparency, strength, surface Adhesive, heat-sealable, and hot-tack properties are reduced. CN1953809A discloses a catalyst for ethylene copolymerization and its preparation method. The catalyst is prepared by reacting a chlorobenzene solution dissolved with metal magnesium powder and dibutyl ether with an activator—a butyl chloride solution containing iodine. , and then react with a chlorobenzene solution containing _PhCCl3 to prepare a magnesium-containing carrier, and then add titanium tetrachloride to the carrier to react to prepare a catalyst. The catalyst has high activity for the copolymerization of ethylene and 1-hexene, and the obtained polymer particle shape is better, but the 1-hexene content in the copolymer is low, only 1.2 wt%. In order to solve the problem of low insertion rate of 1-hexene in ethylene copolymers and obtain ethylene-hexene copolymers with narrow composition distribution and wide molecular weight distribution, many patents modify Ziegler-Natta catalysts by adding electron donors in order to prepare Catalyst system with high activity and good copolymerization performance. The method of ethylene copolymerization disclosed in CN1229092A is to dissolve magnesium chloride in organic epoxy compounds, organic phosphorus compounds and then add electron donors to form a uniform solution, and then react with at least one precipitation aid and transition metal titanium halides and derivatives thereof and obtain; the catalyst catalyzes ethylene and 1-hexene copolymerization activity high, and the 1-hexene insertion rate in the copolymer is higher, but the mother liquor of this catalytic system is more viscous in the preparation process, and it is difficult to separate the catalyst solid from the mother liquor, and the copolymerization The distribution of 1-hexene in the material is uneven. CN1194993A discloses a kind of catalyst that is used for ethylene slurry polymerization, and it is dissolved in the homogeneous solution of organic epoxy compound, organic phosphorus compound and inert solvent by magnesium chloride, then adds electron donor, a kind of co-diluent and transition metal titanium This catalyst can also be used for the copolymerization of ethylene and α-olefin, but there is no example of the copolymerization of ethylene and 1-hexene to form LLDPE.

Therefore, there is still a need to develop a catalyst with higher catalytic activity for the copolymerization of ethylene and α-olefin, so that the prepared LLDPE has a higher α-olefin insertion rate and good performance.

Contents of the invention

In order to solve the above technical problems, the object of the present invention is to provide a catalyst for the copolymerization of ethylene and α-olefin. The catalyst has high catalytic activity for catalyzing the copolymerization of ethylene and long-chain α-olefin, and the long-chain α-olefin insertion rate of the prepared copolymer is high, and the particle shape is good.

The object of the present invention is also to provide a preparation method of the catalyst for the copolymerization of ethylene and α-olefin.

Another object of the present invention is to provide a catalyst composition for copolymerization of ethylene and α-olefin, which comprises the above catalyst.

In order to achieve the above object, the present invention provides a catalyst for the copolymerization of ethylene and α-olefin, the raw materials of which include a magnesium compound, a titanium compound, an electron donor I and an electron donor II;

Wherein, the magnesium compound is one or a combination of several compounds shown in the general formula MgR ¹ _n X ¹ _2-n , where X ¹ is halogen, n is an integer of 0-2, R ¹ is C ₁ -C ₁₅ alkyl or aryl;

The titanium compound is one or a combination of compounds represented by the general formula Ti(OR ² ) _m X ² _4-m , where X ² is a halogen, m is an integer of 0-4, and R ² is C ₁ -C ₆ alkyl or aryl;

The electron donor I is an ester compound;

The electron donor II is a siloxane compound, which is one or a combination of compounds represented by the general formula R ³ _x R ⁴ _y Si(OR ⁵ ) _z , where R ³ is a hydrocarbon group, Chlorinated hydrocarbon or halogen, R ⁴ is hydrocarbon group, chlorinated hydrocarbon or halogen, R ⁵ is hydrocarbon group, 0≤x<2, 0≤y<2, 0<z≤4 and x, y and z are all integers;

The ratio of the magnesium compound, titanium compound, electron donor I and electron donor II is 1 gram magnesium compound: 15.75-62.5 milliliter titanium compound: 0.075-0.375 milliliter electron donor I: 0.10-0.39 milliliter electron donor II.

In the above catalyst, the magnesium compound may be one or a combination of magnesium chloride, magnesium bromide, magnesium iodide and magnesium diethoxide. Preferably, the magnesium compound is magnesium chloride.

In the above-mentioned catalyst, the titanium compound may be one or a combination of titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, tetraethoxytitanium and monochlorotriethoxytitanium, etc. . Preferably, the titanium compound is titanium tetrachloride.

In the above catalyst, the electron donor I (ester compound) can be methyl formate, methyl acetate, ethyl acetate, methyl benzoate, ethyl benzoate, propyl benzoate, succinate di One or a combination of ethyl ester, di-n-butyl phthalate, diisobutyl phthalate, trimethyl phosphate, triethyl phosphate, tributyl phosphate and triphenyl phosphate . Preferably, the electron donor I is one or a combination of diethyl succinate, ethyl benzoate, diisobutyl phthalate and tributyl phosphate.

In the above catalyst, the electron donor II (siloxane compound) can be tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, methyltriethoxysilane, ethyl triethoxysilane, Ethoxysilane, n-Propyltriethoxysilane, Chlorotriethoxysilane, 3-Chloropropyltriethoxysilane, Methyltrimethoxysilane, Ethyltrimethoxysilane, Isobutyl Trimethoxysilane, Hexyltrimethoxysilane, Dimethyldimethoxysilane, Diisopropyldimethoxysilane, Dicyclohexyldimethoxysilane, Cyclohexylmethyldimethoxysilane, Diphenyl One or a combination of phenylmethyldimethoxysilane and phenylmethyldimethoxysilane. Preferably, the electron donor II is tetraethoxysilane, 3-chloropropyltriethoxysilane, hexyltrimethoxysilane, isobutyltrimethoxysilane and diphenyldimethoxysilane, etc. one or a combination of several.

The present invention also provides the preparation method of the above-mentioned catalyst for the copolymerization of ethylene and α-olefin, which comprises the following steps:

Dissolving the magnesium compound in an appropriate amount of hydrocarbon solvent, adding an alcohol solvent, and reacting for 2-4 hours under stirring at 70-90°C;

Then add electron donor I, react under stirring conditions for 0.5-2 hours, then add electron donor II, react under stirring conditions for 0.5-2 hours;

Cool down to room temperature, add titanium compound dropwise, finish dropping within 1-2 hours, then raise the temperature to 70-90°C, and react under stirring for 1-3 hours;

Pressure filter the above reactant to remove the solvent, add an appropriate amount of hydrocarbon solvent and stir, heat up to 70-90°C, add electron donor II, react for 1-2 hours under stirring conditions, then add electron donor I, react under stirring conditions for 1 -2 hours;

Add titanium compound and react for 1-3 hours under stirring condition;

filtering, washing, and drying to obtain the catalyst for the copolymerization of ethylene and α-olefin;

Wherein, the ratio of the magnesium compound, alcohol solvent, titanium compound, electron donor I and electron donor II is 1 gram magnesium compound: 1.5-6.0 ml alcohol solvent: 15.75-62.5 ml titanium compound: 0.075-0.375 ml electron donating Body I: 0.10-0.39 ml of electron donor II; the titanium compound is added in two times, the volume ratio of the first and second additions is 1:2-4:1; electron donor I is added in two times, the second The volume ratio of the first addition to the second addition is 2:1-1:6; the electron donor II is added in two times, and the volume ratio of the first addition to the second addition is 3:1-7:1.

In the above preparation method, the hydrocarbon solvent may be one or a combination of aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons and halogenated hydrocarbons, and the amount of hydrocarbon solvent added is subject to the smooth reaction. Wherein, the aliphatic hydrocarbon can be one or more combinations of pentane, hexane, heptane, octane, decane, etc.; the alicyclic hydrocarbon can be cyclopentane, methylcyclopentane, One or a combination of cyclohexane and methylcyclohexane; the aromatic hydrocarbon can be one or a combination of benzene, toluene, xylene, ethylbenzene and cumene, etc. ; The halogenated hydrocarbon can be one or a combination of carbon tetrachloride, ethylene dichloride, propylene dichloride and chlorobenzene. Preferably, the hydrocarbon solvent is hexane and/or heptane.

In the above preparation method, the alcohol solvent may be aliphatic alcohol and/or alicyclic alcohol. Wherein, the aliphatic alcohol can be methanol, ethanol, isopropanol, isobutanol, pentanol, hexanol, 2-ethylbutanol, 2-ethylhexyl alcohol, octanol, dodecanol, stearyl alcohol Alcohol and ethylene glycol, etc. one or a combination of several; said alicyclic alcohol can be one or a combination of cyclohexanol and methyl cyclohexanol, etc. Preferably, the alcoholic solvent is isobutanol and/or hexanol.

The present invention also provides a catalyst composition for the copolymerization of ethylene and α-olefin, which comprises the following components:

The aforementioned catalysts for the copolymerization of ethylene and α-olefins;

A cocatalyst, which is one or a combination of compounds represented by the general formula R ⁶ _f MX ³ _3-f , where R ⁶ is a C ₁ -C ₁₅ hydrocarbon group, X ³ is a halogen, M is a metal element, f is an integer of 1-3;

Wherein, the molar ratio of the catalyst to the co-catalyst is 1:30-1:150, calculated by the molar amount of the titanium element in the catalyst and the M metal element in the co-catalyst, respectively.

In the above catalyst composition, ^R in the general formula of the cocatalyst can be methyl, ethyl, n-propyl, isobutyl, cyclopentyl, cyclohexyl and phenyl etc.; said M can be aluminum element wait. According to a preferred embodiment of the present invention, the cocatalyst is trimethylaluminum, triethylaluminum, triisobutylaluminum, dimethylaluminum chloride, diethylaluminum chloride, diisobutylaluminum chloride , methylaluminum sesquichloride, ethylaluminum sesquichloride, methylaluminum dichloride and ethylaluminum dichloride, etc. or a combination of several. More preferably, the cocatalyst is triethylaluminum and/or triisobutylaluminum.

The catalyst for the copolymerization of ethylene and α-olefin and the preparation method thereof provided by the invention have the following advantages:

(1) During the preparation process, the purpose of Ziegler-Natta catalyst modification is realized by adding electron donors I and II in stages. The catalyst preparation process is simple, the process flow is short, the operation is convenient, and the cost is low.

(2) The catalyst provided by the present invention can be applied to the copolymerization reaction of ethylene and α-olefin, especially the copolymerization reaction of ethylene and long-chain α-olefin, such as ethylene and 1-hexene, ethylene and 1-octene, ethylene and Copolymerization of 1-decene can produce ethylene-α-olefin copolymers with higher α-olefin content. The catalytic activity of normal pressure polymerization of ethylene and α-olefin can reach more than 550gPE(h·gcat) ^-1 , the content of α-olefin in the prepared copolymer can reach more than 6wt%, and the polymer particles are uniform and in good shape.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the following examples.

Example 1

This embodiment provides a catalyst for the copolymerization of ethylene and α-olefin, which is prepared by the following steps:

(1) Add 2 grams of anhydrous magnesium chloride, 60 milliliters of hexane and 6.5 milliliters of isobutanol into a three-necked flask replaced by argon, stir and heat to 70° C., then react for 3 hours to obtain a suspension;

(2) Add 0.18 ml of tributyl phosphate to the suspension, stir and react at 70°C for 1 hour, then add 0.6 ml of tetraethoxysilane, and stir and react at 70°C for 1 hour;

(3) Cool down to room temperature, slowly add 47 ml of titanium tetrachloride dropwise, the dropwise addition time is 90 minutes, gradually warm up to 70°C, the heating time is 2 hours, and then stir and react for 2 hours;

(4) Then press filter the supernatant, add 50 ml of n-hexane, heat up to 70°C, add 0.10 ml of tetraethoxysilane, stir for 1 hour, then add 0.12 ml of tributyl phosphate, stir for 1 hour ;

(5) Add 23 milliliters of titanium tetrachloride again, react for 2 hours;

(6) After the reaction, wash with n-hexane several times until the unreacted titanium tetrachloride is completely removed, and then vacuum-dry to obtain the solid catalyst 1.

The determination of titanium content in the catalyst is carried out by spectrophotometry. The experimental steps include: dissolving the catalyst with concentrated sulfuric acid, and then adding H ₂ O ₂ to react with it. It forms a yellow complex with Ti ⁴⁺ , and the maximum absorption wavelength is at 420nm Quantitative determination of titanium was carried out by spectrophotometry. The titanium content of this catalyst 1 was 6.11 wt%.

Example 2

This embodiment provides a catalyst for the copolymerization of ethylene and α-olefin, the preparation method of which is the same as that of Example 1, except that:

12 milliliters of isobutanol consumptions in the step (1).

In step (2), diisobutyl phthalate is used to replace tributyl phosphate, and the consumption is 0.06 milliliters; tetraethoxysilane is replaced with isobutyltrimethoxysilane, and the consumption is 0.17 milliliters.

The amount of titanium tetrachloride used in step (3) was 83 milliliters, the time for dropping was 2 hours, and the reaction time was 1 hour.

In step (4), replace tetraethoxysilane with isobutyltrimethoxysilane, and its consumption is 0.03 milliliters, and the reaction time is 2 hours; Replace tributyl phosphate with diisobutyl phthalate, and its consumption is 0.22 milliliters , the reaction time is 2 hours.

In the step (5), the consumption of titanium tetrachloride is 42 milliliters, and the reaction time is 3 hours.

The titanium content of the prepared solid catalyst 2 was 3.54wt%.

Example 3

This embodiment provides a catalyst for the copolymerization of ethylene and α-olefin, the preparation method of which is the same as that of Example 1, except that:

In the step (1), the consumption of isobutanol is 4.30 milliliters.

In step (2), diethyl succinate was used to replace tributyl phosphate, and the amount was 0.30 ml; 3-chloropropyltriethoxysilane was used to replace tetraethoxysilane, and the amount was 0.21 ml.

In the step (3), the amount of titanium tetrachloride is 31 milliliters, the time for dropping is 2 hours, and the reaction time is 1 hour.

In step (4), replace tetraethoxysilane with 3-chloropropyltriethoxysilane, and its consumption is 0.04 milliliters, and the reaction time is 2 hours; Replace tributyl phosphate with diethyl succinate, and its consumption is 0.15 ml.

15.50 milliliters of titanium tetrachloride consumptions in the step (5).

The titanium content of the prepared solid catalyst 3 was 5.20wt%.

Example 4

This embodiment provides a catalyst for the copolymerization of ethylene and α-olefin, the preparation method of which is the same as that of Example 1, except that:

In the step (1), the consumption of isobutanol is 3.0 milliliters.

In step (2), the consumption of tributyl phosphate is 0.05 milliliters; the consumption of tetraethoxysilane is replaced by hexyltrimethoxysilane, and the consumption is 0.40 milliliters.

The amount of titanium tetrachloride used in step (3) was 21 milliliters, the time for dropping was 1 hour, and the reaction time was 3 hours.

In step (4), hexyltrimethoxysilane was used to replace tetraethoxysilane, the amount of which was 0.07 milliliters; the amount of tributyl phosphate was 0.29 milliliters.

In the step (5), the amount of titanium tetrachloride was 10.5 milliliters, and the reaction time was 1 hour.

The titanium content of the prepared solid catalyst 4 was 6.60wt%.

Example 5

This embodiment provides a catalyst for the copolymerization of ethylene and α-olefin, the preparation method of which is the same as that of Example 1, except that:

9.20 milliliters of isobutanol consumptions in the step (1).

In step (2), ethyl benzoate is used to replace tributyl phosphate, and the amount is 0.30 ml; diphenyltrimethoxysilane is used to replace tetraethoxysilane, and the amount is 0.41 ml.

In the step (3), the amount of titanium tetrachloride was 66 milliliters, and the time for dropping was 2 hours.

In step (4), replace tetraethoxysilane with diphenyltrimethoxysilane, and its consumption is 0.07 milliliters, and the reaction time is 2 hours; Replace tributyl phosphate with ethyl benzoate, and its consumption is 0.45 milliliters, and the reaction time is 2 hours.

33 milliliters of titanium tetrachloride consumptions in the step (5).

The titanium content of the prepared solid catalyst 5 was 6.63wt%.

Example 6

This embodiment provides a catalyst for the copolymerization of ethylene and α-olefin, the preparation method of which is the same as that of Example 1, except that:

5.40 milliliters of isobutanol consumptions in the step (1).

In step (2), diethyl succinate was used to replace tributyl phosphate, and the amount was 0.18 ml; 3-chloropropyltriethoxysilane was used to replace tetraethoxysilane, and the amount was 0.65 ml.

38 milliliters of titanium tetrachloride consumptions in the step (3).

In step (4), 3-chloropropyltriethoxysilane was used to replace tetraethoxysilane, and the amount was 0.11 ml; diethyl succinate was used to replace tributyl phosphate, and the amount was 0.10 ml.

In the step (5), the amount of titanium tetrachloride was 19 milliliters, and the reaction time was 3 hours.

The titanium content of the prepared solid catalyst 6 was 3.42wt%.

Example 7

This embodiment provides a catalyst for the copolymerization of ethylene and α-olefin, the preparation method of which is the same as that of Example 1, except that:

In step (1), octane was used instead of hexane, and the reaction was carried out at 90° C. for 2 hours.

In step (2), the reaction temperature is 90° C., and the reaction time is 0.5 hours; the tetraethoxysilane is replaced by isobutyltrimethoxysilane, and the reaction time is 2 hours.

In step (3), the reaction temperature of titanium tetrachloride is 90° C., and the reaction time is 1 hour.

In step (4), the reaction temperature is 90° C., and tetraethoxysilane is replaced by isobutyltrimethoxysilane.

The titanium content of the prepared solid catalyst 7 was 5.01 wt%.

Example 8

This embodiment provides a catalyst for the copolymerization of ethylene and α-olefin, the preparation method of which is the same as that of Example 1, except that:

In step (1), hexane was replaced by octane, isobutanol was replaced by hexanol, and the reaction was carried out at 90° C. for 4 hours.

In step (2), the reaction temperature is 90° C., and tributyl phosphate is replaced with diethyl succinate.

In the step (3), the amount of titanium tetrachloride was 19 milliliters, and the reaction temperature was 90° C.

In step (4), the reaction temperature is 90° C., and tributyl phosphate is replaced with diethyl succinate.

The titanium content of the prepared solid catalyst 8 was 5.12wt%.

Example 9

This embodiment provides a catalyst for the copolymerization of ethylene and α-olefin, the preparation method of which is the same as that of Example 1, except that:

5.4 milliliters of isobutanol consumptions in the step (1).

The amount of tributyl phosphate used in step (2) is 0.25 milliliters, and the reaction time is 2 hours; the tetraethoxysilane is 0.35 milliliters, and the reaction time is 0.5 hours.

44 milliliters of titanium tetrachloride consumptions in the step (3).

Step (4) The amount of tetraethoxysilane used is 0.05 ml, and the amount of tributyl phosphate used is 0.25 ml.

22 milliliters of titanium tetrachloride consumptions in the step (5).

The titanium content of the prepared solid catalyst 9 was 4.18wt%.

Example 10

This embodiment provides a catalyst for the copolymerization of ethylene and α-olefin, the preparation method of which is the same as that of Example 1, except that:

In step (2), the consumption of tributyl phosphate is 0.30 milliliters, and the consumption of tetraethoxysilane is 0.20 milliliters.

Step (4) The amount of tetraethoxysilane used is 0.066 ml, and the amount of tributyl phosphate used is 0.40 ml.

33 milliliters of titanium tetrachloride consumptions in the step (5).

The titanium content of the prepared solid catalyst 10 was 5.03wt%.

Application example 1-12

Application examples 1-12 provide the polymerization reaction methods and results of catalysts 1-10 prepared in the above examples catalyzing the copolymerization of ethylene and α-olefin under different conditions. In the polymerization reaction, ethylene and α-olefin were copolymerized in a 250 ml three-necked flask, and the ethylene pressure was 0.1 MPa. Its polymerization method comprises the following steps: after the there-necked flask is fully replaced with argon, 100 milliliters of n-hexane treated with anhydrous and oxygen-free is added, and a certain amount of 2.0 mol/liter (mol/L) triethylaluminum solution (helped catalyst), add a certain amount of catalyst while stirring, raise the temperature to 45°C, add 1.86-3.8mL of comonomer, and polymerize by ethylene for 0.5 hours. After completion of the reaction, add 10% acidified ethanol to terminate the reaction, and wash the polymer with ethanol, weigh the polymer after vacuum drying, calculate the catalytic activity, and the catalytic activity is calculated by the polymer weight (grams) produced per gram of catalyst per hour , unit: gPE(h·gcat) ^-1 .

The polymerization conditions and polymerization results of application examples 1-12 are shown in Table 1, wherein the α-olefin content was measured by ¹³ C-NMR method, and the content of polymer fine powder below 150 μm was measured by sieve method.

As shown in Table 1, the catalytic activity of normal pressure polymerization of ethylene and 1-hexene reaches 570-872gPE(h·gcat) ^-1 , and the content of 1-hexene in the prepared copolymer is 6.54-10.6% (mass percentage ); ethylene and 1-octene, 1-decene normal pressure polymerization activity is greater than 705gPE (h·gcat) ^-1 , and the content of 1-octene, 1-decene in the prepared copolymer is greater than 7% (mass percentage ); the prepared copolymer has a fine powder content below 150 μm and is less than 5 (wt%). Can draw by table 1 experimental result: catalyst provided by the present invention can be applied to ethylene and long-chain α-olefin copolymerization reaction, as ethylene and 1-hexene, ethylene and 1-octene, ethylene and 1-decene Copolymerization can produce ethylene and α-olefin copolymers with high α-olefin content, and the obtained polymer particles are uniform and in good shape.

Table 1

Claims (10)

1. A catalyst for the copolymerization of ethylene and α-olefin, the raw material of which comprises a magnesium compound, a titanium compound, an electron donor I and an electron donor II; Wherein, the magnesium compound is one or a combination of several compounds shown in the general formula MgR ¹ _n X ¹ _2-n , where X ¹ is halogen, n is an integer of 0-2, R ¹ is C ₁ -C ₁₅ alkyl or aryl; The titanium compound is one or a combination of compounds represented by the general formula Ti(OR ² ) _m X ² _4-m , where X ² is a halogen, m is an integer of 0-4, and R ² is C ₁ -C ₆ alkyl or aryl; The electron donor I is an ester compound; The electron donor II is a siloxane compound, which is one or a combination of compounds represented by the general formula R ³ _x R ⁴ _y Si(OR ⁵ ) _z , where R ³ is a hydrocarbon group, Chlorinated hydrocarbon or halogen, R ⁴ is hydrocarbon group, chlorinated hydrocarbon or halogen, R ⁵ is hydrocarbon group, 0≤x<2, 0≤y<2, 0<z≤4 and x, y and z are all integers; The ratio of the magnesium compound, titanium compound, electron donor I and electron donor II is 1 gram magnesium compound: 15.75-62.5 milliliter titanium compound: 0.075-0.375 milliliter electron donor I: 0.10-0.39 milliliter electron donor II. 2. The catalyst according to claim 1, wherein the magnesium compound is one or a combination of magnesium chloride, magnesium bromide, magnesium iodide and magnesium diethoxide. 3. The catalyst according to claim 1, wherein the titanium compound is one of titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, tetraethoxytitanium and monochlorotriethoxytitanium or a combination of several. 4. catalyst according to claim 1, wherein, described electron donor I is methyl formate, methyl acetate, ethyl acetate, methyl benzoate, ethyl benzoate, propyl benzoate, succinic acid One or a combination of diethyl ester, di-n-butyl phthalate, diisobutyl phthalate, trimethyl phosphate, triethyl phosphate, tributyl phosphate and triphenyl phosphate . 5. The catalyst according to claim 1, wherein the electron donor II is tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, methyltriethoxysilane, ethyltriethyl Oxysilane, n-Propyltriethoxysilane, Chlorotriethoxysilane, 3-Chloropropyltriethoxysilane, Methyltrimethoxysilane, Ethyltrimethoxysilane, Isobutyltrimethoxysilane Oxysilane, Hexyltrimethoxysilane, Dimethyldimethoxysilane, Diisopropyldimethoxysilane, Dicyclohexyldimethoxysilane, Cyclohexylmethyldimethoxysilane, Diphenyl One or a combination of dimethoxysilane and phenylmethyldimethoxysilane. 6. the preparation method of the catalyst that is used for the copolymerization of ethylene and alpha-olefin described in any one of claim 1-5, it comprises the following steps: Dissolving the magnesium compound in a hydrocarbon solvent, adding an alcohol solvent, and reacting for 2-4 hours under stirring at 70-90°C; Then add electron donor I, react under stirring conditions for 0.5-2 hours, then add electron donor II, react under stirring conditions for 0.5-2 hours; Cool down to room temperature, add titanium compound dropwise, finish dropping within 1-2 hours, then raise the temperature to 70-90°C, and react under stirring for 1-3 hours; Press filter the above reaction product to remove the solvent, add hydrocarbon solvent and stir, heat up to 70-90°C, add electron donor II, react under stirring conditions for 1-2 hours, then add electron donor I, react under stirring conditions 1- 2 hours; Add titanium compound and react for 1-3 hours under stirring condition; filtering, washing, and drying to obtain the catalyst for the copolymerization of ethylene and α-olefin; Wherein, the ratio of the magnesium compound, alcohol solvent, titanium compound, electron donor I and electron donor II is 1 gram magnesium compound: 1.5-6.0 ml alcohol solvent: 15.75-62.5 ml titanium compound: 0.075-0.375 ml electron donating Body I: 0.10-0.39 ml electron donor II; the titanium compound is added in two times, the volume ratio of the first and second additions is 1:2-4:1; electron donor I is added in two times, the second The volume ratio of the first addition to the second addition is 2:1-1:6; the electron donor II is added twice, and the volume ratio of the first addition to the second addition is 3:1-7:1. 7. The preparation method according to claim 6, wherein the hydrocarbon solvent is one or a combination of aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons and halogenated hydrocarbons. 8. The preparation method according to claim 6, wherein the alcohol solvent is an aliphatic alcohol and/or an alicyclic alcohol. 9. A catalyst composition for the copolymerization of ethylene and α-olefin, comprising the following components: The catalyst for the copolymerization of ethylene and alpha-olefins described in any one of claims 1-5; A cocatalyst, which is one or a combination of compounds represented by the general formula R ⁶ _f MX ³ _3-f , where R ⁶ is a C ₁ -C ₁₅ hydrocarbon group, X ³ is a halogen, M is a metal element, and f is an integer of 1-3. 10. The catalyst composition according to claim 9, wherein the cocatalyst is trimethylaluminum, triethylaluminum, triisobutylaluminum, dimethylaluminum chloride, diethylaluminum chloride, One or a combination of diisobutyl aluminum chloride, methyl aluminum sesquichloride, ethyl aluminum sesquichloride, methyl aluminum dichloride and ethyl aluminum dichloride.