A process for the polymerization of olefins

Abstract

The present application belongs to the technical field of olefin polymerization catalysts, and relates to an olefin polymerization method. The olefin polymerization method comprises the following steps: allowing a mixture of an olefin and an alcohol compound to react with a catalyst system; wherein the catalyst system comprises the reaction product of the following components: (1) a solid catalyst component comprising titanium, magnesium, halogen and an internal electron donor compound; the magnesium compound is a dialkoxymagnesium; (2) an alkyl aluminum compound; and (3) an external electron donor compound. The alcohol compound introduced by the catalyst system in the polymerization process improves the stereospecificity of the catalyst, and the polymerization activity and hydrogen sensitivity are basically unchanged, which is beneficial to the production of high-performance polymer products while maintaining good comprehensive performance of the catalyst.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of olefin polymerization catalysts, and particularly relates to an olefin polymerization method. BACKGROUND

[0002] It is known that a catalyst system used in the homopolymerization or copolymerization of α-olefins is generally composed of three parts, specifically including: (1) a main catalyst (a solid catalyst component), (2) a cocatalyst (usually an alkyl aluminum compound), and (3) an external electron donor compound added during polymerization.

[0003] It is known to those skilled in the art that one or more external electron donor compounds are used in the polymerization process to control the stereoregularity and morphology of the polymer. In addition to affecting the stereoregularity of the polymer, the external electron donor often also affects other properties of the catalyst to varying degrees.

[0004] In the process of olefin polymerization, in addition to the external electron donor, the presence of other components also has varying degrees of influence on the polymerization process.

[0005] It is known that non-propylene components in the raw material propylene will have varying degrees of influence on the polymerization result. For example, the presence of a small amount of ethylene will increase the polymerization activity of the catalyst, while affecting the stereoregularity of the polymer. The presence of different amounts of trace amounts of water and oxygen will reduce the polymerization activity of the catalyst to varying degrees, while affecting other properties of the catalyst.

[0006] For a specific catalyst, the addition of a certain amount of non-propylene component during polymerization to optimize the polymerization performance of the catalyst is a problem to be solved by the present patent. SUMMARY

[0007] The present inventors have unexpectedly found that, in the process of olefin polymerization, the addition of a small amount of an alcohol compound to a solid catalyst component containing titanium, magnesium, halogen, and an internal electron donor compound can, in combination with a specific solid catalyst component under the same polymerization conditions, produce a polymer with excellent comprehensive performance. By adjusting the polymerization conditions, the resulting catalyst system exhibits substantially unchanged polymerization activity and hydrogen sensitivity, and the stereodirecting property of the catalyst is improved to varying degrees. Based on this discovery, the present application is proposed.

[0008] To achieve the object of the present application, the present application provides an olefin polymerization method, including the following steps:

[0009] contacting an olefin and a mixture of alcohol compounds with a catalyst system for reaction;

[0010] The catalyst system comprises a reaction product of the following components:

[0011] (1) a solid catalyst component comprising titanium, magnesium, halogen and an internal electron donor compound; the magnesium compound is a dialkyl magnesium;

[0012] (2) an alkyl aluminum compound;

[0013] (3) an external electron donor compound.

[0014] The alcohol compound introduced in the polymerization process of the catalyst system of the present application can improve the stereospecificity of the catalyst, and the polymerization activity and hydrogen sensitivity are basically unchanged, which is beneficial to the production of high-performance polymer products while maintaining good comprehensive performance of the catalyst.

[0015] Other features and advantages of the present application will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0016] The exemplary embodiments of the present application will be described in more detail by combining the accompanying drawings.

[0017] Figure 1 A schematic diagram showing the effect of alcohol content on the performance of catalyst A is shown.

[0018] Figure 2 A schematic diagram showing the effect of methanol content on the performance of catalyst B is shown. DETAILED DESCRIPTION

[0019] The specific embodiments of the present application will be described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0020] In order to achieve the purpose of the present application, the present application provides an olefin polymerization method, comprising the following steps:

[0021] The mixture of olefins and alcohol compounds is reacted with the catalyst system;

[0022] The catalyst system comprises the reaction product of the following components:

[0023] (1) a solid catalyst component comprising titanium, magnesium, halogen and an internal electron donor compound; the magnesium compound is a dialkyl magnesium;

[0024] (2) an alkyl aluminum compound;

[0025] (3) an external electron donor compound.

[0026] The solid catalyst component of the present application can be prepared by contacting a dialkyl magnesium carrier with a titanium compound and an internal electron donor compound in an inert diluent to obtain a solid catalyst component;

[0027] According to the present application, preferably, the alcohol compound is a linear or branched mono- or polyhydric alcohol.

[0028] Specific alcohol compounds are: methanol, ethanol, n-propanol, n-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, n-nonanol, n-decanol, 2-propanol, 2-butanol, 2-pentanol, 2-hexanol, 2-heptanol, 2-octanol, 2-nonanol, 2-decanol, 2-ethylbutanol, 2-ethylhexanol, 4-methyl-2-pentanol, 3,3,5-trimethylpentanol, 4-methyl-3-heptanol, benzyl alcohol, 2-phenylethanol, 1-phenyl-1-propanol, ethylene glycol, glycerol, and the like. The alcohol compound used can be a mixture of one or more alcohols.

[0029] In the present application, the mass content of one or more alcohols in the alcohol and propylene mixture is less than 5%, preferably less than 1%, and more preferably less than 0.1%.

[0030] In the present application, during the polymerization process, the alcohol compound of the present application is first mixed uniformly with propylene, and then the solid catalyst component, the alkyl aluminum compound cocatalyst, and the external electron donor are added to the propylene mixture for polymerization reaction.

[0031] In the present application, the dialkoxy magnesium carrier is prepared by the following method: under the protection of an inert atmosphere, alcohol and magnesium metal are used as raw materials, and refluxed in the presence of a halogenating agent; wherein the weight ratio of alcohol to magnesium is 4-50:1; the alcohol is a linear or branched mono- or polyhydric alcohol; the halogenating agent is selected from at least one of halogen elements and halides, and the molar ratio of halogen atoms to magnesium is 0.0002-0.2:1.

[0032] Preferably, the alcohol is ethanol and 2-ethylhexanol. The halogenating agent is preferably selected from iodine and magnesium chloride.

[0033] In this invention, the internal electron-donating compound is selected from at least one of mono- or multi-component aliphatic and aromatic carboxylic acid esters; the internal electron-donating compound is selected, for example, from benzoic acid esters, phthalic acid esters, malonic acid esters, succinic acid esters, glutaric acid esters, etc. Preferably, the internal electron-donating compound is selected from ethyl benzoate, diethyl phthalate, diisobutyl phthalate, di-n-butyl phthalate, diisooctyl phthalate, di-n-octyl phthalate, diethyl malonate, dibutyl malonate, diethyl 2,3-diisopropylsuccinate, diisobutyl 2,3-diisopropylsuccinate, di-n-butyl 2,3-diisopropylsuccinate, dimethyl 2,2-dimethylsuccinate, etc. At least one of the following: diisobutyl succinate, 2-ethyl-2-methylsuccinate, diethyl 2-ethyl-2-methylsuccinate, diethyl adipate, dibutyl adipate, diethyl sebacate, dibutyl sebacate, diethyl maleate, di-n-butyl maleate, diethyl naphthalene dicarboxylate, dibutyl naphthalene dicarboxylate, triethyl trimellitate, tributyl trimellitate, triethyl phenyltrimethylbenzene, tributyl phenyltrimethylbenzene, tetraethyl pyromellitic acid, and tetrabutyl pyromellitic acid.

[0034] According to the present invention, preferably, the titanium compound has the general formula Ti(OR) w ) 4－k X' k R w For C1~C 20 The alkyl group, X' is Cl, Br or I, and k is an integer from 0 to 4.

[0035] According to the present invention, preferably, the titanium compound is selected from at least one of titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, titanium tetrabutoxy, titanium tetraethoxy, titanium monochlorotriethoxy, titanium dichlorodiethoxy, and titanium trichloroethoxy.

[0036] According to the present invention, in the solid catalyst component, the amount of the titanium compound is 0.5-150 moles per mole of magnesium.

[0037] In this invention, the alkylaluminum compound has the general formula AlR”’ d X 1 3-d , where R”' is C l -C8 alkyl, X 1 For halogen atoms, 0 < d ≤ 3, and when containing two or three R'', they can be the same or different. Preferably, the alkylaluminum compound is triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, or Al(n-C6H)2O. 13 3. Al(n-C8H) 17 At least one of )3 and AlEt2Cl.

[0038] Preferably, the molar ratio of aluminum in the aluminum alkyl compound to titanium in the solid catalyst component is 1-1000:1, more preferably 1-500:1.

[0039] In the present application, the aluminum alkyl compound and the external electron donor compound can be contacted with the solid catalyst component separately or as a mixture of the two components.

[0040] According to different requirements for polymer properties, the catalyst system of the present application can be directly used in the polymerization of olefins; or it can be first subjected to prepolymerization with olefins to form a prepolymerization catalyst, and then subjected to polymerization with olefins.

[0041] In the present application, the general formula of the olefin can be CH2=CH-R V , wherein R V is hydrogen or C1-C6 alkyl. Non-limiting examples of the olefin include ethylene, propylene, butylene, pentene, hexene, octene, 4-methyl-1-pentene. Preferably, the olefin is propylene and / or ethylene; more preferably, the olefin is propylene.

[0042] In addition, according to specific use requirements, the olefin can be subjected to polymerization in the presence of a small amount of diene.

[0043] In the present application, the olefin polymerization reaction can be carried out in liquid phase (liquid monomer or monomer dissolved in inert solvent) or gas phase, or it can be carried out under the combined operation of liquid phase and gas phase polymerization stages. The olefin polymerization reaction can be carried out according to known polymerization techniques, for example, using conventional techniques such as slurry method, gas phase fluidized bed, etc.

[0044] In the present application, the olefin polymerization conditions include a polymerization temperature of 0-150℃, preferably 60-90℃, and a polymerization pressure of normal pressure or higher.

[0045] The present application is further illustrated below with reference to examples, but the scope of the present application is not limited to these examples.

[0046] In the following examples and comparative examples:

[0047] 1) The isotacticity index of the polymer was determined by n-heptane extraction method according to GB / T 2412-2008. After 2g of dried polymer sample was placed in an extractor and extracted with boiling n-heptane for 6 hours, the remaining material was dried to constant weight; the ratio of the obtained polymer weight (g) to 2 was the isotacticity index.

[0048] 2) The melt index of the polymer was determined according to GB 3682-2000 at 230℃ under a load of 2.16kg.

[0049] Preparation example 1 and 2 are the preparation methods of the solid catalyst component of the embodiment and the comparative example of the present application respectively.

[0050] Preparation example 1

[0051] Preparation of alkoxy magnesium:

[0052] The preparation method of alkoxy magnesium can refer to the preparation methods of patent documents 200910176719.X, 201010283034.8, 201010522125.2, 201110172225.1, 201410573756.5, etc., the relevant contents disclosed therein are all incorporated into the present application as reference.

[0053] Specifically, after the 1L reactor with stirrer, reflux condenser, thermometer and burette was sufficiently replaced by nitrogen, 550ml ethanol with water content less than 200ppm and 10ml isopropanol with water content less than 200ppm were added into the reactor, 0.68g iodine and 0.42g magnesium chloride were added, and after stirring, the temperature was raised until the reflux temperature of the reaction system was reached, then 32g magnesium powder and 90ml toluene were added, and the reaction was carried out until no hydrogen was discharged. Then washing, separation and drying were carried out to obtain the dialkoxy magnesium carrier.

[0054] Preparation of catalyst:

[0055] The preparation method of catalyst can refer to the preparation methods of patent documents 200910176719.X, 201010283034.8, 201010522125.2, 201110172225.1, 201410573756.5, etc., the relevant contents disclosed therein are all incorporated into the present application as reference.

[0056] Specifically, in the 300ml reactor repeatedly replaced by high-purity nitrogen, 10ml toluene and 90ml titanium tetrachloride were added, and the temperature was lowered to-5℃, then the suspension prepared by 10g alkoxy magnesium obtained from preparation example 1 and 50ml toluene was added, and then the temperature was slowly raised to 80℃, 2ml DNBP (dibutyl phthalate) was added, and the temperature was continuously raised to 115℃, and kept for 2 hours, and the liquid was filtered clean. Then 120ml titanium tetrachloride and 30ml toluene mixture were added, the temperature was raised to 110℃, and stirring treatment was carried out for 1 hour, and the treatment was repeated for 3 times, and the obtained solid was washed with 150ml hexane at 60℃ for 4 times, the liquid was filtered, and after drying, 10.5g solid powder was obtained, which was the solid catalyst component A.

[0057] Preparation example 2

[0058] Preparation of catalyst:

[0059] In a 300 ml glass reactor flask, 90 ml (820 mmol) of titanium tetrachloride was added and cooled to -20°C, 37 mmol of magnesium halide carrier (prepared according to the method disclosed in CN1330086A Example 1) was added, then the temperature was raised to 110°C, and 0.3 mmol of tributyl phosphate and 7.3 mmol of 2-isopropyl-2-isopentyl-1,3-dimethoxypropane were added during the temperature rising process, after maintaining at 110°C for 30 min, the liquid was filtered, washed with titanium tetrachloride for 2 times, washed with hexane for 5 times, and dried under vacuum to obtain catalyst component B for olefin polymerization.

[0060] Examples 1-27 are used to illustrate the catalyst system and the olefin polymerization method of the present application.

[0061] Examples 1-9

[0062] In a 5 liter autoclave, purged with nitrogen gas flow at 70°C for 1 hour, then replaced with 3 times of gaseous propylene, closed the autoclave, introduced a set amount of hydrogen and 0.6 kg of liquid propylene and a set amount of methanol, raised the temperature to a set temperature, and stirred at high speed for 30 min; under the protection of nitrogen, introduced 0.4 kg of propylene, 5 mL of hexane solution of triethylaluminum (TEAL, the concentration of triethylaluminum is 0.5 mmol / mL), 1 mL of hexane solution of methylcyclohexyldimethoxysilane (C-donor, the concentration of C-donor is 0.1 mmol / mL), 8 mL of anhydrous hexane and 4 mg of solid catalyst component A into the autoclave. The temperature in the autoclave was quickly raised to 70°C under stirring. After 1 hour of polymerization reaction at 70°C, the stirring was stopped, the un-polymerized propylene monomer was removed, the polymer was collected, and dried under vacuum at 70°C for 2 hours, thereby obtaining polypropylene.

[0063] The amount of methanol added, the properties of polypropylene of the catalyst system, etc. are shown in Table 1 and Figure 1 .

[0064] Examples 10-18

[0065] The propylene polymerization was carried out according to the method of Example 1-9, except that the alcohol introduced during polymerization was changed from methanol to ethanol.

[0066] The amount of ethanol added, the properties of polypropylene of the catalyst system, etc. are shown in Table 1 and Figure 1 .

[0067] Examples 19-21

[0068] The propylene polymerization was carried out according to the method of Example 1-9, except that the alcohol introduced during polymerization was a mixture of methanol and ethanol, and the ratio of methanol to ethanol was 1:1.

[0069] The amount of alcohol added, the properties of the polypropylene produced by the catalyst system, etc. are shown in Table 1.

[0070] Examples 22-24

[0071] The polymerization of propylene was carried out according to the procedure of Examples 1-9, except that a mixture of methanol and 2-ethylhexanol was introduced during polymerization, in a ratio of 1:1.

[0072] The amount of alcohol added, the properties of the polypropylene produced by the catalyst system, etc. are shown in Table 1.

[0073] Examples 25-27

[0074] The polymerization of propylene was carried out according to the procedure of Examples 1-9, except that a mixture of methanol and 2-ethylhexanol was introduced during polymerization, in a ratio of 1:1.

[0075] The amount of alcohol added, the properties of the polypropylene produced by the catalyst system, etc. are shown in Table 1.

[0076] Comparative Examples 1-11

[0077] The polymerization of propylene was carried out according to the procedure of Examples 1-11, except that solid catalyst component B was used instead of A as the main catalyst during polymerization. The amount of alcohol added, the properties of the polypropylene produced by the catalyst system, etc. are shown in Table 1 and Figure 2

[0078] Table 1

[0079]

[0080]

[0081] As can be seen from Table 1, in Examples 1-27, the catalyst A was used and alcohol compounds were added during polymerization, the isotacticity of the polymer was further improved, while in Comparative Examples 2-11, the catalyst B was used and alcohol compounds were added, the isotacticity of the polymer was reduced.

[0082] The foregoing description of various embodiments of the application has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the application to the precise form disclosed, and various modifications and variations are possible in the light of the above teachings. It is intended that the scope of the application be limited not with the above description but rather determined by the claims appended hereto.

[0083] ​The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as exactly that endpoint point. The endpoints of the ranges and any values are understood to be approximate values. For ranges having an upper and lower limit, the range can be understood to include each integer within the defined range. The upper and lower limits of the range can independently be included in the range, or independently excluded from the range. The range can also be understood to include single values within the range, which can be the upper or lower limit of the range. For ranges having an upper and lower limit, the range can be understood to include each integer within the defined range. The upper and lower limits of the range can independently be included in the range, or independently excluded from the range. The range can also be understood to include single values within the range, which can be the upper or lower limit of the range.

Claims

1. A process for the polymerization of olefins, characterized in that, The method comprises the following steps: contacting a mixture of an olefin and an alcohol compound with a catalyst system; wherein the catalyst system comprises a reaction product of the following components: (1) a solid catalyst component comprising titanium, magnesium, halogen and an internal electron donor compound; the magnesium compound is a dialkoxymagnesium; (2) an alkylaluminum compound; (3) an external electron donor compound; the alcohol compound is selected from at least one of methanol, ethanol, n-propanol, n-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, n-nonanol, n-decanol, 2-propanol, 2-butanol, 2-pentanol, 2-hexanol, 2-heptanol, 2-octanol, 2-nonanol, 2-decanol, 2-ethylbutanol, 2-ethylhexanol, 4-methyl-2-pentanol, 3,3,5-trimethylpentanol, 4-methyl-3-heptanol, benzyl alcohol, 2-phenylethanol, 1-phenyl-1-propanol, ethylene glycol and glycerol; the mass content of alcohol in the mixture of the olefin and the alcohol compound is <1 wt%.

2. The olefin polymerization process of claim 1, wherein, the mass content of alcohol in the mixture of the olefin and the alcohol compound is <0.1 wt%.

3. The olefin polymerization process of claim 1, wherein, The preparation method of the dialkoxymagnesium comprises the following steps: under the protection of an inert atmosphere, refluxing alcohol and magnesium metal as raw materials in the presence of a halogenating agent; wherein the weight ratio of the alcohol to the magnesium metal is 4-50:1; the alcohol is a linear or branched monohydric alcohol or polyhydric alcohol; the halogenating agent is selected from at least one of halogen elements and halides, and the amount of the halogenating agent is such that the molar ratio of halogen atoms to magnesium is 0.0002-0.2:

1.

4. The olefin polymerization process of claim 3, wherein, the alcohol is ethanol and / or 2-ethylhexanol.

5. The olefin polymerization process of claim 3, wherein, the halogenating agent is iodine and / or magnesium chloride.

6. The olefin polymerization process of claim 1, wherein, the internal electron donor compound is selected from at least one of monohydric or polyhydric aliphatic carboxylate and aromatic carboxylate compounds.

7. The olefin polymerization process of claim 6, wherein, the internal electron donor compound is selected from at least one of benzoate, phthalate, malonate, succinate and glutarate.

8. The olefin polymerization process of claim 7, wherein, the internal electron donor compound is selected from at least one of ethyl benzoate, diethyl phthalate, diisobutyl phthalate, di-n-butyl phthalate, diisooctyl phthalate, di-n-octyl phthalate, diethyl malonate, dibutyl malonate, diethyl 2,3-diisopropyl succinate, diisobutyl 2,3-diisopropyl succinate, di-n-butyl 2,3-diisopropyl succinate, dimethyl 2,3-diisopropyl succinate, diisobutyl 2,2-dimethyl succinate, diisobutyl 2-ethyl-2-methyl succinate, diethyl 2-ethyl-2-methyl succinate, diethyl adipate, dibutyl adipate, diethyl sebacate, dibutyl sebacate, diethyl maleate, di-n-butyl maleate, diethyl naphthalene dicarboxylate, dibutyl naphthalene dicarboxylate, triethyl trimellitate, tributyl trimellitate, triethyl trimesate, tributyl trimesate, tetraethyl pyromellitate and tetra-n-butyl pyromellitate.

9. The olefin polymerization process of claim 1, wherein, Ti(OR w ) 4－k X' k wherein R w is a C1-C 20 alkyl group, X' is Cl, Br or I, and k is an integer from 0 to 4; the amount of the titanium compound in the solid catalyst component is 0.5-150 moles per mole of magnesium.

10. The olefin polymerization process of claim 9, wherein, The titanium compound is selected from at least one of titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, titanium tetrabutoxide, titanium tetraethoxide, titanium trichloroethoxide, titanium dichlorodiethoxide, and titanium chloroethoxide.

11. The olefin polymerization process of claim 1, wherein, The general formula of the aluminum alkyl compound is AlR''' d X 1 3-d wherein R'" is a C l -C8 alkyl, X 1 is a halogen atom, 0 < d < 3, and R'" is the same or different when two or three R'" are present.

12. The olefin polymerization process of claim 11, wherein, The alkyl aluminum compound is at least one of triethyl aluminum, triisobutyl aluminum, tri-n-butyl aluminum, tri-n-hexyl aluminum, Al(n-C6H 13 )3, Al(n-C8H 17 )3, and AlEt2Cl.

13. The olefin polymerization process of claim 11, wherein, The molar ratio of aluminum in the aluminum alkyl compound to titanium in the solid catalyst component is 1-1000:

1.

14. The olefin polymerization process of claim 13, wherein, The molar ratio of aluminum in the aluminum alkyl compound to titanium in the solid catalyst component is 1-500:

1.

15. The olefin polymerization process of claim 1, wherein, The external electron donor compound is methylcyclohexyldimethoxysilane or dicyclopentyldimethoxysilane.

16. The olefin polymerization process of claim 1, wherein, The olefin has the general formula CH2=CH-R V wherein R V is hydrogen or C1-C6 alkyl.

17. The olefin polymerization process of claim 16, wherein, The olefin is selected from at least one of ethylene, propylene, butene, pentene, hexene, octene, and 4-methyl-1-pentene.

18. The olefin polymerization process of claim 17, wherein, The olefin is propylene and / or ethylene.

19. The olefin polymerization process of claim 18, wherein, The olefin is propylene.

20. The olefin polymerization process of claim 1, wherein, The conditions of the contact reaction include that the polymerization temperature is 0-150°C, and the polymerization pressure is normal pressure or higher.

21. The olefin polymerization process of claim 20, wherein, The polymerization temperature is 60-90°C.

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