CN114773506A

CN114773506A - Catalyst for in-situ nucleation of polypropylene and preparation method and application thereof

Info

Publication number: CN114773506A
Application number: CN202210606075.9A
Authority: CN
Inventors: 郑伟平; 王观亚; 丁其维; 韩晓倩; 杨金玲; 袁文博; 赵永臣; 王耀伟; 栾波; 马韵升
Original assignee: Chambroad Chemical Industry Research Institute Co Ltd; Shandong Chambroad Petrochemicals Co Ltd
Current assignee: Chambroad Chemical Industry Research Institute Co Ltd; Shandong Chambroad Petrochemicals Co Ltd
Priority date: 2022-05-31
Filing date: 2022-05-31
Publication date: 2022-07-22

Abstract

The invention provides a catalyst for in-situ nucleating polypropylene and a preparation method and application thereof. The catalyst provided by the invention comprises a main catalyst; the main catalyst comprises: (1) titanium halide, wherein the content of Ti in the main catalyst is 1.0-5.0 wt%; (2) magnesium halide, wherein the content of Mg in the main catalyst is 5 to 10 weight percent; (3) the content of the internal electron donor in the main catalyst is 0.2 to 20 weight percent; (4) the content of the polymer alpha nucleating agent in the main catalyst is 30 to 80 weight percent; wherein the internal electron donor is selected from one or more of succinate shown in a formula (a) and alkyl diether shown in a formula (b); the polymer alpha nucleating agent is a polyolefin-based compound. The catalyst provided by the invention can be directly used as an in-situ nucleating agent in propylene polymerization without being modified by the catalyst, and the crystallinity and crystallization temperature of polypropylene are improved.

Description

Catalyst for in-situ nucleation of polypropylene and preparation method and application thereof

Technical Field

The invention relates to the field of catalytic synthesis, and particularly relates to a catalyst for in-situ nucleated polypropylene, and a preparation method and application thereof.

Background

Ziegler-Natta (Z-N) type catalysts are well known in the field of polymers and, in general, they comprise a main catalyst component formed of a transition metal compound of groups 4 to 6 of the periodic Table, a metal compound of groups 1 to 3, and an internal electron donor compound, a cocatalyst and an external electron donor.

The polypropylene has excellent physical and mechanical properties and chemical properties. However, since polypropylene is a semi-crystalline polymer and has the disadvantages of slow crystallization rate, low crystallinity, and easy formation of large-sized spherulites during molding, the performance and application thereof are greatly limited, and methods for improving the above disadvantages by adding a nucleating agent to polypropylene are well known in the art.

The method of adding the nucleating agent into polypropylene can be divided into traditional processing nucleation and in-situ nucleation. In the traditional processing and nucleating process, a high-performance nucleating agent is added in the post-processing and granulating process of polypropylene, the concentration is usually 500-2000 ppm, the concentration and the cost of the nucleating agent are high, and the nucleating agent cannot be uniformly dispersed, so that the quality stability of a product is influenced; the in-situ nucleation is to directly form or add a nucleating agent in the propylene synthesis process, the method can uniformly disperse the nucleating agent in the polypropylene, the concentration of the nucleating agent is low and is only 20-500 ppm, and the performance of the produced polypropylene is more excellent.

The use of polymeric nucleating agents for the manufacture of nucleated propylene polymers is well known in the art. Patents such as WO 99/24478A1, CN 1106409C, CN 103619942B, CN 106459269B, CN 109196003B, CN 106795305B and the like in northern Europe chemical industry report related technologies and applications of using a prepolymerized vinyl compound as a polymer nucleating agent; patent CN 1026116C of the japan mitsui chemical discloses a method for synthesizing a polymeric nucleating agent using a vinyl compound (3-methyl-1-butene) as a raw material of the nucleating agent and its use. It can be seen from the patent reports that the use of vinyl compounds as nucleating raw materials for the preparation of polymer nucleating agents is inexpensive and readily available, and the resulting products have excellent properties.

The polymeric nucleating agents described in the above patents are typically prepared in the presence of the catalyst used to prepare the polypropylene in a catalyst modification prepolymerization step prior to the polymerization of the propylene. I.e. the catalyst is modified by polymerizing vinyl monomers in the presence of said catalyst. For example, methods wherein such modified catalysts are used are described in CN 106795305B, CN 1106409C or CN 106459269B.

Typically, the polymerization of vinyl monomers to obtain a modified catalyst takes place in a medium in which the catalyst is also fed to the propylene polymerization process. The medium usually used is an oil or a highly viscous hydrocarbon medium, suitable in the case of modified catalysts which are fed directly to the polymerization reactor after their preparation. However, it is not feasible if it is desired to use it in a batch process where solid catalysts are typically used in the polymerization of propylene or other processes where the solvent requirements of the system are stringent. Although patent CN 109196003B reports a solid catalyst for preparing nucleated polyolefins, the above problems can be solved. However, the preparation method still comprises the steps of firstly preparing the solid catalyst, then modifying the solid catalyst through the polymerization of the vinyl monomer, and finally drying the solid catalyst to obtain the solid catalyst containing the polymer nucleating agent, namely drying the solid in the system after the known catalyst modification, and not directly obtaining the catalyst containing the polymer nucleating agent in the process of preparing the catalyst. The preparation process is cumbersome and there is a loss of catalyst.

Disclosure of Invention

In view of the above, the present invention aims to provide a catalyst for in-situ nucleation of polypropylene, and a preparation method and application thereof. The catalyst provided by the invention can be directly used as an in-situ nucleating agent in propylene polymerization without being modified by the catalyst, and promotes the high-efficiency synthesis of the in-situ nucleated polypropylene with high crystallinity and high crystallization temperature.

The invention provides a catalyst for in-situ nucleating polypropylene, which comprises a main catalyst;

the main catalyst comprises:

(1) titanium halide, wherein the content of Ti in the main catalyst is 1.0-5.0 wt%;

(2) magnesium halide, wherein the content of Mg in the main catalyst is 5 to 10 weight percent;

(3) the content of the internal electron donor in the main catalyst is 0.2 to 20 weight percent;

(4) the content of the polymer alpha nucleating agent in the main catalyst is 30-80 wt%;

wherein:

the internal electron donor is selected from one or more of succinate shown in formula (a) and alkyl diether shown in formula (b);

in formula (a):

R₁、R₂independently selected from: c₁～C₂₀A linear or branched alkyl, alkenyl, cycloalkyl, aryl, aralkyl or alkaryl group;

R₃、R₄、R₅、R₆independently selected from: hydrogen, C₁～C₂₀A linear or branched alkyl, alkenyl, alkynyl, cycloalkyl, aryl, aralkyl or alkaryl group; and R is₃～R₆Is not hydrogen at the same time;

in the formula (b):

R₁、R₂independently selected from: c₁～C₂₀Linear or branched alkyl, C₃～C₂₀Substituted or unsubstituted cycloalkyl, C₆～C₂₀Substituted or unsubstituted aryl, C₇～C₂₀Substituted or unsubstituted aralkyl;

R₃、R₄、R₅、R₆、R₇、R₈independently selected from: hydrogen, halogen, C₁～C₂₀Linear or branched alkyl, C₃～C₂₀Substituted or unsubstituted cycloalkyl, C₆～C₂₀Substituted or unsubstituted aryl, C₇～C₂₀Substituted or unsubstituted aralkyl; and R is₃～R₈Not hydrogen at the same time;

the polymer alpha nucleating agent is a polyolefin-based compound.

Preferably, the polymeric alpha nucleating agent is selected from at least one of polyvinylcyclohexane, polyvinylcyclopentane, polyvinyl-2-methylcyclohexane, poly-3-methyl-1-butene, poly-3-ethyl-1-hexene, poly-3-methyl-1-pentene and polystyrene.

Preferably, the titanium halide is selected from at least one of titanium tetrachloride, titanium tetrabromide, and titanium tetraiodide;

the magnesium halide is anhydrous magnesium dichloride and/or anhydrous magnesium dibromide.

Preferably, the succinate represented by the formula (a) is selected from at least one of the following compounds:

diethyl 2, 3-diisopropylsuccinate, dipropyl 2, 3-diisopropylsuccinate, diisopropyl 2, 3-diisopropylsuccinate, dibutyl 2, 3-diisopropylsuccinate, diisobutyl 2, 3-diisopropylsuccinate, diethyl 2, 3-dipropylsuccinate, dipropyl 2, 3-dipropylsuccinate, diisopropyl 2, 3-dipropylsuccinate, dibutyl 2, 3-dipropylsuccinate, diisobutyl 2, 3-dipropylsuccinate, diethyl 2, 3-dibutylsuccinate, dipropyl 2, 3-dibutylsuccinate, diisopropyl 2, 3-dibutylsuccinate, diisobutyl 2, 3-dibutylsuccinate, diethyl 2, 3-diisobutylsuccinate, Dipropyl 2, 3-diisobutylsuccinate, diisopropyl 2, 3-diisobutylsuccinate, dibutyl 2, 3-diisobutylsuccinate, diisobutyl 2, 3-diisobutylsuccinate;

the alkyl diether represented by the formula (b) is selected from at least one of the following compounds:

2- (2-ethylhexyl) -1, 3-dimethoxypropane, 2-isopropyl-1, 3-dimethoxypropane, 2-butyl-1, 3-dimethoxypropane, 2-sec-butyl-1, 3-dimethoxypropane, 2-cyclohexyl-1, 3-dimethoxypropane, 2-phenyl-1, 3-dimethoxypropane, 2- (2-phenylethyl) -1, 3-dimethoxypropane, 2- (2-cyclohexylethyl) -1, 3-dimethoxypropane, 2- (p-chlorophenyl) -1, 3-dimethoxypropane, 2- (2-phenylmethyl) -1, 3-dimethoxypropane, 2-phosphonomethyliminopropyl, isopropylphenyl-1, 3-dimethoxypropane, 2-phosphonomethyliminopropyl, 2-carbonylpropyl, 3-dimethoxypropane, 2-carbonylpropyl, 2-carbonylmethyl, 3-dimethoxypropane, 2-iodopropyl, 2-carbonylmethyl, 2-methyl, 2-dimethylolmethyl, 2,3, and, 2, 2-dicyclohexyl-1, 3-dimethoxypropane, 2-diethyl-1, 3-dimethoxypropane, 2-dipropyl-1, 3-dimethoxypropane, 2-diisopropyl-1, 3-dimethoxypropane, 2-dibutyl-1, 3-dimethoxypropane, 2-diisobutyl-1, 3-dimethoxypropane, 2-methyl-2-propyl-1, 3-dimethoxypropane, 2-methyl-2-ethyl-1, 3-dimethoxypropane, 2-methyl-2-isopropyl-1, 3-dimethoxypropane, 2-methyl-2-phenyl-1, 3-dimethoxypropane, 2-methyl-2-cyclohexyl-1, 3-dimethoxypropane, 2-methyl-2-isobutyl-1, 3-dimethoxypropane, 2-isobutyl-2-isopropyl-1, 3-dimethoxypropane, 2-isopropyl-2-isoamyl-1, 3-dimethoxypropane, 2-phenyl-2-isopropyl-1, 3-dimethoxypropane, 2-phenyl-2-sec-butyl-1, 3-dimethoxypropane, 2-cyclopentyl-2-isopropyl-1, 3-dimethoxypropane, 2-cyclohexyl-2-isopropyl-1, 3-dimethoxypropane, 2-cyclohexyl-2-sec-butyl-1, 3-dimethoxypropane, 2-isopropyl-2-sec-butyl-1, 3-dimethoxypropane, 2-cyclohexyl-2-cyclohexylmethyl-1, 3-dimethoxypropane.

Preferably, the catalyst further comprises: cocatalyst and external electron donor;

the cocatalyst is an alkyl aluminum compound;

the external electron donor is a silane compound;

the molar ratio of the cocatalyst to the titanium halide in the main catalyst is (50-200) to 1; the molar ratio of the external electron donor to the main catalyst titanium halide is (5-30) to 1.

Preferably, the cocatalyst is selected from at least one of triethylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, diethyl-aluminum monochloride, diisobutyl-aluminum monochloride, dihexyl-aluminum monochloride and dioctyl-aluminum monochloride;

the external electron donor is selected from the group consisting of vinyltriethoxysilane, vinyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, diethyldimethoxysilane, dipropyldimethoxysilane, diisopropyldimethoxysilane, dibutyldimethoxysilane, diisobutyldimethoxysilane, di-tert-butyldimethoxysilane, di-tert-hexyldimethoxysilane, diphenyldimethoxysilane, dicyclohexyldimethoxysilane, dicyclopentyldimethoxysilane, dimethyldiethoxysilane, diethyldiethoxysilane, dipropyldiethoxysilane, diisopropyldiethoxysilane, dibutyldiethoxysilane, diisobutyldiethoxysilane, di-tert-butyldiethoxysilane, di-tert-hexyldiethoxysilane, diphenyldiethoxysilane, dicyclohexyldiethoxysilane, di-tert-butyldiethoxysilane, dimethyldimethoxysilane, di-tert-hexyldiethoxysilane, dimethyldimethoxysilane, di-tert-butyldimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldimethoxysilane, at least one of dicyclopentyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, cyclopentylmethyl-dimethoxysilane, cyclopentyltrimethoxysilane, cyclohexylmethyldimethoxysilane, cyclohexyltrimethoxysilane, thexyltrimethoxysilane, t-butyltrimethoxysilane, and thexyltrimethoxysilane.

The invention also provides a preparation method of the catalyst for in-situ nucleating of polypropylene, which comprises the following steps:

a) mixing an alcohol compound, magnesium halide and an organic solvent for reaction to obtain a magnesium halide alcohol compound solution;

b) mixing the magnesium halide alcoholate solution with titanium halide to obtain a mixed solution 1;

c) mixing the mixed solution 1 with an internal electron donor to obtain a mixed solution 2;

d) mixing the mixed solution 2 with titanium halide for reaction to obtain a mixed solution 3;

e) carrying out solid-liquid separation on the mixed solution 3 to obtain a solid 4;

f) mixing the solid 4 with aluminum alkyl, alkane solvent and vinyl compound for reaction, and then carrying out solid-liquid separation to obtain main catalyst powder.

Preferably, in step a):

the organic solvent is decane;

the alcohol compound is at least one selected from ethanol, n-propanol, isopropanol, n-butanol, isobutanol, pentanol, isoamylol and higher fatty alcohol with more than C6;

the reaction temperature is 80-150 ℃, and the reaction time is 0.5-5 h;

in the step b), the volume ratio of the magnesium halide alcohol compound solution to the titanium halide is (0.1-5) to 1;

the step b) specifically comprises the following steps:

firstly, cooling the magnesium halide alcoholate solution to-50-0 ℃, and then adding cold titanium halide for mixing to obtain a mixed solution 1;

wherein the temperature of the cold titanium halide is-25 to 0 ℃.

Preferably, in step c):

the molar ratio of the internal electron donor to the magnesium halide in the step a) is (0.005-0.3) to 1;

the mixing temperature is 0-50 ℃;

in the step d):

the volume ratio of the titanium halide to the titanium halide in the step b) is 1 to (0.5-2);

the reaction temperature is 80-130 ℃, and the reaction time is 2-5 h;

in step f):

the mass ratio of the alkyl aluminum to the solid 4 is (0.01-1) to 1;

the volume ratio of the alkane solvent to the alkyl aluminum is (50-200) to 1;

the mass ratio of the vinyl compound to the solid 4 is (0.1-15) to 1;

the step f) specifically comprises the following steps:

mixing alkyl aluminum and an alkane solvent, adding a solid 4, reacting at 0-30 ℃ for 0.1-0.5 h, adding a vinyl compound, heating to 30-65 ℃ for reacting for 1-30 h, and then carrying out solid-liquid separation to obtain main catalyst powder.

Preferably, in step f):

the vinyl compound is at least one selected from vinyl cyclohexane, vinyl cyclopentane, vinyl-2-methyl cyclohexane, 3-methyl-1-butene, 3-ethyl-1-hexene, 3-methyl-1-pentene and styrene;

the alkyl aluminum is selected from at least one of triethyl aluminum, triisobutyl aluminum, diethyl aluminum monochloride and trioctyl aluminum;

the alkane solvent is selected from at least one of n-pentane, isopentane, n-hexane and n-heptane.

The invention also provides the application of the catalyst in the technical scheme or the catalyst containing the main catalyst obtained by the preparation method in the technical scheme as an in-situ nucleating agent in propylene polymerization.

The invention also provides a preparation method of the in-situ nucleated polypropylene, which comprises the following steps:

s1, mixing a propylene monomer with a catalyst, and carrying out prepolymerization reaction to obtain a prepolymer;

s2, adding a propylene monomer and hydrogen into the system, and carrying out polymerization reaction to obtain polypropylene;

wherein, the catalyst is the catalyst in the technical scheme or the catalyst containing the main catalyst obtained by the preparation method in the technical scheme.

Preferably, in the step S1, the temperature of the prepolymerization is 0-50 ℃, and the time is less than or equal to 2 hours;

in step S2:

the temperature of the polymerization reaction is 50-80 ℃, and the time is 1-5 h;

the pressure of the hydrogen is 0.1-10 bar;

the molar ratio of the propylene monomer in the step S1 to the propylene monomer in the step S2 is 1: 3-10.

The invention provides a catalyst for in-situ nucleating polypropylene, which comprises a main catalyst; the main catalyst comprises: (1) titanium halide, wherein the content of Ti in the main catalyst is 1.0-5.0 wt%; (2) magnesium halide, wherein the content of Mg in the main catalyst is 5 to 10 weight percent; (3) the content of the internal electron donor in the main catalyst is 0.2 to 20 weight percent; (4) the content of the polymer alpha nucleating agent in the main catalyst is 30-80 wt%; wherein the internal electron donor is selected from one or more of succinate shown in a formula (a) and alkyl diether shown in a formula (b); the polymer alpha nucleating agent is a polyolefin-based compound. The main catalyst powder prepared by the invention can be directly used as an in-situ nucleating agent in propylene polymerization without being modified by a catalyst, is solid powder, does not contain any solvent, and unreacted vinyl compounds are removed by drying, can be directly added into a reactor or dispersed in white oil to be added into the reactor in the propylene polymerization process to initiate propylene monomers to polymerize and synthesize in-situ nucleated polypropylene, and can obtain the polypropylene with high crystallinity and high crystallization temperature, wherein the crystallinity of the obtained polypropylene is more than 55 percent, and the crystallization temperature is more than 128 ℃.

Detailed Description

The invention provides a catalyst for in-situ nucleated polypropylene, which comprises a main catalyst;

the main catalyst comprises:

(2) magnesium halide, wherein the content of Mg in the main catalyst is 5-10 wt%;

(4) the content of the polymer alpha nucleating agent in the main catalyst is 30 to 80 weight percent;

wherein:

the internal electron donor is selected from one or more of succinate shown in a formula (a) and alkyl diether shown in a formula (b);

in formula (a):

R₃、R₄、R₅、R₆independently selected from: hydrogen, C₁～C₂₀Linear or branched alkyl, alkenyl, alkynyl, cycloalkyl, aryl, aralkyl or alkaryl groups; and R is₃～R₆Not hydrogen at the same time;

in the formula (b):

R₃、R₄、R₅、R₆、R₇、R₈independently selected from: hydrogen, halogen, C₁～C₂₀Linear or branched alkyl, C₃～C₂₀Substituted or unsubstituted cycloalkyl, C₆～C₂₀Substituted or unsubstituted aryl, C₇～C₂₀Substituted or unsubstituted aralkyl; and R is₃～R₈Is not hydrogen at the same time;

the polymer alpha nucleating agent is a polyolefin-based compound.

[ with respect to component 1 ]: titanium halides

In the present invention, the titanium halide is preferably at least one of titanium tetrachloride, titanium tetrabromide, and titanium tetraiodide.

In the present invention, the content of Ti in the titanium halide in the main catalyst is preferably 1.0 wt% to 5.0 wt%, and specifically may be 1.0 wt%, 2.0 wt%, 3.0 wt%, 4.0 wt%, or 5.0 wt%.

[ with respect to component 2 ]: magnesium halide

In the present invention, the magnesium halide is preferably an anhydrous magnesium halide, more preferably an anhydrous magnesium dichloride and/or an anhydrous magnesium dibromide.

In the present invention, the content of Mg in the magnesium halide in the main catalyst is preferably 5 wt% to 10 wt%, and specifically may be 5.0 wt%, 6.0 wt%, 7.0 wt%, 8.0 wt%, 9.0 wt%, 10.0 wt%.

[ with respect to component 3 ]: internal electron donor

In the invention, the internal electron donor is selected from one or more of succinate shown in formula (a) and alkyl diether shown in formula (b);

in formula (a):

R₃、R₄、R₅、R₆independently selected from: hydrogen, C₁～C₂₀A linear or branched alkyl, alkenyl, alkynyl, cycloalkyl, aryl, aralkyl or alkaryl group; and R is₃～R₆Not hydrogen at the same time;

in the formula (b):

R₁、R₂independently selected from: c₁～C₂₀Linear or branched alkyl, C₃～C₂₀A substituted or unsubstituted cycloalkyl group,C₆～C₂₀Substituted or unsubstituted aryl, C₇～C₂₀Substituted or unsubstituted aralkyl;

R₃、R₄、R₅、R₆、R₇、R₈independently selected from: hydrogen, halogen, C₁～C₂₀Linear or branched alkyl, C₃～C₂₀Substituted or unsubstituted cycloalkyl, C₆～C₂₀Substituted or unsubstituted aryl, C₇～C₂₀Substituted or unsubstituted aralkyl; and R is₃～R₈Not hydrogen at the same time.

In the present invention, more preferably, the succinate represented by the formula (a) is selected from at least one of the following compounds:

diethyl 2, 3-diisopropylsuccinate, dipropyl 2, 3-diisopropylsuccinate, diisopropyl 2, 3-diisopropylsuccinate, dibutyl 2, 3-diisopropylsuccinate, diisobutyl 2, 3-diisopropylsuccinate, diethyl 2, 3-dipropylsuccinate, dipropyl 2, 3-dipropylsuccinate, diisopropyl 2, 3-dipropylsuccinate, diisobutyl 2, 3-dipropylsuccinate, diethyl 2, 3-dibutylsuccinate, dipropyl 2, 3-dibutylsuccinate, diisopropyl 2, 3-dibutylsuccinate, diisobutyl 2, 3-dibutylsuccinate, diethyl 2, 3-dibutylsuccinate, diisopropyl 2, 3-dibutylsuccinate, diisobutyl 2, 3-diisobutylsuccinate, diethyl 2, 3-diisobutylsuccinate, Dipropyl 2, 3-diisobutylsuccinate, diisopropyl 2, 3-diisobutylsuccinate, dibutyl 2, 3-diisobutylsuccinate and diisobutyl 2, 3-diisobutylsuccinate.

In the present invention, more preferably, the alkyl diether represented by the formula (b) is selected from at least one of the following compounds:

2- (2-ethylhexyl) -1, 3-dimethoxypropane, 2-isopropyl-1, 3-dimethoxypropane, 2-butyl-1, 3-dimethoxypropane, 2-sec-butyl-1, 3-dimethoxypropane, 2-cyclohexyl-1, 3-dimethoxypropane, 2-phenyl-1, 3-dimethoxypropane, 2- (2-phenylethyl) -1, 3-dimethoxypropane, 2- (2-cyclohexylethyl) -1, 3-dimethoxypropane, 2- (p-chlorophenyl) -1, 3-dimethoxypropane, 2- (2-phenylmethyl) -1, 3-dimethoxypropane, 2-methyl-2-dimethoxypropane, 2-methyl-1, 3-dimethoxypropane, 2-methyl-1, 3-dimethoxypropane, 2-butyl-1, 3-dimethoxypropane, 2-sec-butyl-1, 3-dimethoxypropane, 2-cyclohexyl-1, 3-dimethoxypropane, 2-phenyl-1, 3-dimethoxypropane, 2-phenyl-propyl-propane, 2-phenyl-methyl-2-methyl-dimethoxypropane, 2-propyl-2-methyl-2-methyl-2, 2-propyl-2-methyl-propyl-2, 2-ethyl-2, 2-propyl-methyl-2, 2-methyl-ethyl-methyl-2, 2-ethyl-1, 2-ethyl-1, 3-methyl-propyl-2-methyl-propyl, 2-ethyl-2, 3-methyl-ethyl, 2, 3-propyl-ethyl, 2-ethyl, 2-methyl-propyl-ethyl, 2-2, 3-ethyl, 2-propyl, 2,3, 2,3, 2,3, 2,3, 2,2, 2-dicyclohexyl-1, 3-dimethoxypropane, 2-diethyl-1, 3-dimethoxypropane, 2-dipropyl-1, 3-dimethoxypropane, 2-diisopropyl-1, 3-dimethoxypropane, 2-dibutyl-1, 3-dimethoxypropane, 2-diisobutyl-1, 3-dimethoxypropane, 2-methyl-2-propyl-1, 3-dimethoxypropane, 2-methyl-2-ethyl-1, 3-dimethoxypropane, 2-methyl-2-isopropyl-1, 3-dimethoxypropane, 2-methyl-2-phenyl-1, 3-dimethoxypropane, 2-methyl-2-cyclohexyl-1, 3-dimethoxypropane, 2-methyl-2-isobutyl-1, 3-dimethoxypropane, 2-isobutyl-2-isopropyl-1, 3-dimethoxypropane, 2-isopropyl-2-isoamyl-1, 3-dimethoxypropane, 2-phenyl-2-isopropyl-1, 3-dimethoxypropane, 2-phenyl-2-sec-butyl-1, 3-dimethoxypropane, 2-cyclopentyl-2-isopropyl-1, 3-dimethoxypropane, 2-cyclohexyl-2-isopropyl-1, 3-dimethoxypropane, 2-cyclohexyl-2-sec-butyl-1, 3-dimethoxypropane, 2-isopropyl-2-sec-butyl-1, 3-dimethoxypropane, 2-cyclohexyl-2-cyclohexylmethyl-1, 3-dimethoxypropane.

In the invention, the content of the internal electron donor in the main catalyst is 0.2 wt% to 20 wt%, and specifically may be 0.2 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%.

[ with respect to component 4 ]: polymeric alpha nucleating agent

In the present invention, the polymeric alpha nucleating agent is a polyolefin-based compound, i.e., a vinyl-containing polymer. In the present invention, it is preferable that the polymeric alpha nucleating agent is at least one selected from the group consisting of polyvinylcyclohexane, polyvinylcyclopentane, polyvinyl-2-methylcyclohexane, poly-3-methyl-1-butene, poly-3-ethyl-1-hexene, poly-3-methyl-1-pentene and polystyrene.

In the present invention, the content of the polymer alpha nucleating agent in the main catalyst is 30 wt% to 80 wt%, and specifically may be 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%.

[ with respect to other components ]:

according to the invention, the catalyst preferably further comprises: cocatalyst and external electron donor.

In the present invention, the cocatalyst is an alkyl aluminum compound, preferably at least one of triethylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, diethylaluminum monochloride, diisobutylaluminum monochloride, dihexylaluminum monochloride and dioctylaluminum monochloride. In the invention, the molar ratio of the titanium halide in the cocatalyst to the main catalyst is preferably (50-200) to 1, and specifically can be 50: 1, 60: 1, 70: 1, 80: 1, 90: 1, 100: 1, 110: 1, 120: 1, 130: 1, 140: 1, 150: 1, 160: 1, 170: 1, 180: 1, 190: 1 and 200: 1.

In the present invention, the external electron donor is a silane compound, preferably vinyltriethoxysilane, vinyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, diethyldimethoxysilane, dipropyldimethoxysilane, diisopropyldimethoxysilane, dibutyldimethoxysilane, diisobutyldimethoxysilane, di-t-butyldimethoxysilane, di-t-hexyldimethoxysilane, diphenyldimethoxysilane, dicyclohexyldimethoxysilane, dicyclopentyldimethoxysilane, dimethyldiethoxysilane, diethyldiethoxysilane, dipropyldiethoxysilane, diisopropyldiethoxysilane, dibutyldiethoxysilane, diisobutyldiethoxysilane, di-t-butyldiethoxysilane, di-t-hexyldiethoxysilane, diphenyldiethoxysilane, di-t-butyldiethoxysilane, di-t-hexyldiethoxysilane, di-t-butyldiethoxysilane, di-t-hexyldiethoxysilane, di-hexyldimethoxysilane, di-t-hexyldimethoxysilane, di-butyldimethoxysilane, di-t-butyldimethoxysilane, di-t-butyldimethoxysilane, di-butyldimethoxysilane, a (di-butyldimethoxysilane, a di-a-butyldimethoxysilane, a di-butyldimethoxysilane, a-a bis (a-t-a-butyldimethoxysilane, a di-butyldiethoxysilane, a-or a-or a-bis-or a-a compound, At least one of dicyclohexyldiethoxysilane, dicyclopentyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, cyclopentylmethyldimethoxysilane, cyclopentyltrimethoxysilane, cyclohexylmethyldimethoxysilane, cyclohexyltrimethoxysilane, thexyltrimethoxysilane, t-butyltrimethoxysilane and thexyltrimethoxysilane. In the invention, the molar ratio of the external electron donor to the main catalyst titanium halide is preferably (5-30): 1, and specifically can be 5: 1, 6: 1, 7: 1, 8: 1, 9: 1, 10: 1, 11: 1, 12: 1, 13: 1, 14: 1, 15: 1, 16: 1, 17: 1, 18: 1, 19: 1, 20: 1, 21: 1, 22: 1, 23: 1, 24: 1, 25: 1, 26: 1, 27: 1, 28: 1, 29: 1 and 30: 1.

In the invention, when the catalyst is actually used, the main catalyst, the cocatalyst and the external electron donor are respectively and independently added into a reaction system, namely the main catalyst, the cocatalyst and the external electron donor are respectively used as independent products, and the main catalyst is sold as an independent commercial product.

[ with respect to step a ]:

a) mixing an alcohol compound, magnesium halide and an organic solvent for reaction to obtain a magnesium halide alcohol compound solution.

In the present invention, the alcohol compound is preferably at least one of ethanol, n-propanol, isopropanol, n-butanol, isobutanol, pentanol, isoamyl alcohol, and higher fatty alcohol having C6 or more.

In the present invention, the kind of the magnesium halide is the same as that described in the above technical scheme, and specifically, the magnesium halide is anhydrous magnesium halide, and is preferably anhydrous magnesium dichloride and/or anhydrous magnesium dibromide.

In the present invention, the organic solvent is preferably decane.

In the invention, the mol ratio of the alcohol compound to the magnesium halide is preferably (1-8) to 1, and specifically can be 1: 1, 2: 1, 3: 1, 4: 1, 5: 1, 6: 1, 7: 1 and 8: 1. In the invention, the mol ratio of the organic solvent to the magnesium halide is preferably (1-10) to 1, and specifically can be 1: 1, 2: 1, 3: 1, 4: 1, 5: 1, 6: 1, 7: 1, 8: 1, 9: 1 and 10: 1.

In the invention, the reaction temperature is preferably 80-150 ℃, and specifically can be 80 ℃, 90 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃ and 150 ℃. The reaction time is preferably 0.5-5 h, and specifically can be 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h and 5 h.

In the present invention, the reaction is preferably carried out under a protective atmosphere. The type of gas for providing the protective atmosphere is not particularly limited in the present invention, and may be any inert gas conventionally used in the art, such as nitrogen, helium, argon, or the like.

And (b) carrying out a complexation reaction on the alcohol compound and magnesium halide in a decane medium in the step a) to obtain a magnesium chloride alcohol compound solution.

[ regarding step b ]:

b) and mixing the magnesium halide alcoholate solution with titanium halide to obtain a mixed solution 1.

In the present invention, the kind of the titanium halide is the same as that described in the above technical means, and specifically, at least one of titanium tetrachloride, titanium tetrabromide and titanium tetraiodide is preferable.

In the invention, the volume ratio of the magnesium halide alcoholate solution to the titanium halide is preferably (0.1-5) to 1, and specifically can be 0.1: 1, 0.2: 1, 0.3: 1, 0.4: 1, 0.5: 1, 1.0: 1, 1.5: 1, 2.0: 1, 2.5: 1, 3.0: 1, 3.5: 1, 4.0: 1, 4.5: 1 and 5.0: 1.

In the present invention, the step b) preferably specifically comprises: firstly, cooling the magnesium halide alcohol compound solution to-50-0 ℃, and then adding cold titanium halide for mixing to obtain a mixed solution 1.

Wherein the cooling temperature can be-50 deg.C, -45 deg.C, -40 deg.C, -35 deg.C, -30 deg.C, -25 deg.C, -20 deg.C, -15 deg.C, -10 deg.C, -5 deg.C, and 0 deg.C. The temperature of the cold titanium halide is preferably-25-0 ℃, and specifically can be-25 ℃, 20 ℃, 15 ℃, 10 ℃, 5 ℃ and 0 ℃.

In the present invention, the mixing is preferably stirring mixing. The stirring and mixing time is preferably 0.5-1 h. After mixing, a mixed solution 1 is obtained.

In step b) of the invention, the magnesium halide alcoholate solution is mixed with titanium halide, which is coordinately adsorbed on magnesium chloride.

[ with respect to step c ]:

c) and mixing the mixed solution 1 with an internal electron donor to obtain a mixed solution 2.

In the present invention, the kind of the internal electron donor is the same as that described in the foregoing technical solution, and is not described herein again.

In the invention, the molar ratio of the internal electron donor to the magnesium halide in the step a) is preferably (0.005-0.3) to 1, and specifically can be 0.005: 1, 0.01: 1, 0.05: 1, 0.10: 1, 0.15: 1, 0.20: 1, 0.25: 1 and 0.30: 1.

In the present invention, the mixing temperature is preferably 0 to 50 ℃, and specifically may be 0 ℃, 5 ℃, 10 ℃, 15 ℃, 20 ℃, 25 ℃, 30 ℃, 35 ℃, 40 ℃, 45 ℃ and 50 ℃. Specifically, the mixed solution 1 is heated to 0-50 ℃, and then the internal electron donor is added and mixed at the temperature, so that the mixed solution 2 is obtained.

In the step c), the mixed solution 1 is mixed with an internal electron donor, and the internal electron donor is coordinated and adsorbed on magnesium chloride to form a structure of magnesium halide loaded titanium halide and the internal electron donor.

[ with respect to step d ]:

d) and mixing the mixed solution 2 with titanium halide for reaction to obtain a mixed solution 3.

In the present invention, unlike in step b), the titanium halide used in this step is not necessarily a cold titanium halide, and may be at a temperature of from room temperature to 130 ℃.

In the invention, the volume ratio of the titanium halide to the titanium halide in the step b) is preferably 1: 0.5-2, and more preferably 1: 1.

In the invention, the reaction temperature is preferably 80-130 ℃, and specifically can be 80 ℃, 90 ℃, 100 ℃, 110 ℃, 120 ℃ and 130 ℃. In the invention, the time for raising to the target temperature is preferably 1-3 h, namely, the temperature is raised to 80-130 ℃ within 1-3 h. In the invention, the reaction time is preferably 2-5 h, and specifically can be 2h, 3h, 4h and 5 h.

In the present invention, the step d) preferably specifically comprises: firstly, heating the mixed solution 2 to 80-130 ℃, standing, then adding titanium halide, and keeping the temperature for constant-temperature reaction to obtain a mixed solution 3. Wherein the standing time is preferably 0.5-3 h, and more preferably 1 h.

The invention goes through step d), titanium halide is coordinately adsorbed on magnesium halide.

[ with respect to step e ]:

e) and (3) carrying out solid-liquid separation on the mixed solution 3 to obtain a solid 4.

The solid-liquid separation mode is not particularly limited in the invention, and the solid-liquid separation mode can be a conventional solid-liquid separation mode in the field, such as filtration and the like.

The invention forms magnesium halide spherical particles loaded with internal electron donor and titanium halide through the steps a) -d), and the magnesium halide spherical particles are suspended in the mixed solution of alkane solvent and alcohol.

In the present invention, after the solid-liquid separation, it is preferable to further perform: washing the solid isolate with an alkane solvent. Wherein the alkane solvent is preferably at least one of n-hexane, isopentane, n-hexane, and n-heptane. The washing temperature is preferably 40-60 ℃; specifically, the alkane solvent may be heated to the above-mentioned temperature, and then washed with the hot alkane solvent. The number of washing is preferably 1 to 6. After washing, a spherical solid 4 was obtained.

[ regarding step f ]:

f) and mixing the solid 4 with aluminum alkyl, an alkane solvent and a vinyl compound for reaction, and then carrying out solid-liquid separation to obtain main catalyst powder.

In the present invention, the aluminum alkyl is preferably at least one of triethylaluminum, triisobutylaluminum, diethylaluminum monochloride and trioctylaluminum. In the invention, the mass ratio of the alkyl aluminum to the solid 4 is preferably (0.01-1) to 1, and specifically can be 0.01: 1, 0.05: 1, 0.1: 1, 0.2: 1, 0.3: 1, 0.4: 1, 0.5: 1, 0.6: 1, 0.7: 1, 0.8: 1, 0.9: 1 and 1: 1.

In the present invention, the alkane solvent is preferably at least one of n-pentane, isopentane, n-hexane, and n-heptane. In the invention, the volume ratio of the alkane solvent to the alkyl aluminum is (50-200) to 1, and specifically can be 50: 1, 75: 1, 100: 1, 125: 1, 150: 1, 175: 1 and 200: 1.

In the present invention, the vinyl compound is preferably at least one of vinylcyclohexane, vinylcyclopentane, vinyl-2-methylcyclohexane, 3-methyl-1-butene, 3-ethyl-1-hexene, 3-methyl-1-pentene and styrene. In the present invention, the mass ratio of the vinyl compound to the solid 4 is preferably (0.1-15): 1, and specifically may be 0.1: 1, 1: 1, 2: 1, 3: 1, 4: 1, 5: 1, 6: 1, 7: 1, 8: 1, 9: 1, 10: 1, 11: 1, 12: 1, 13: 1, 14: 1, or 15: 1.

In the invention, the reaction temperature is preferably 30-65 ℃, and specifically can be 30 ℃, 35 ℃, 40 ℃, 45 ℃, 50 ℃, 55 ℃, 60 ℃ and 65 ℃. The reaction time is preferably 1-30 h.

In the present invention, said step f) preferably specifically comprises:

The mixing time of the alkyl aluminum and the alkane solvent is preferably 0.1-2 h, namely, after the alkyl aluminum and the alkane solvent are mixed for 0.1-2 h, the solid 4 is added. In the present invention, the reaction is carried out at 0 to 30 ℃ after the addition of the solid 4, and the temperature may be specifically 0 ℃, 5 ℃, 10 ℃, 15 ℃, 20 ℃, 25 ℃ and 30 ℃. The reaction time at the temperature is preferably 0.1 to 0.5h, and more preferably 0.2 h. After the reaction, adding a vinyl compound, and heating to 30-65 ℃, specifically 30 ℃, 35 ℃, 40 ℃, 45 ℃, 50 ℃, 55 ℃, 60 ℃ and 65 ℃. The time for heating to the target temperature is preferably 0.5-3 h, namely, the temperature is raised to the target temperature within 0.5-3 h. The time of the heat preservation reaction is preferably 1-30 h after the target temperature is reached.

The magnesium halide loaded titanium halide and the spherical compound of the internal electron donor obtained in the previous step of the reaction are subjected to polymerization reaction with alkyl aluminum and a vinyl compound to generate the polymer alpha nucleating agent, and the polymer alpha nucleating agent is uniformly distributed on the surface of the spherical particles of the compound. In the polymerization reaction, titanium halide is reacted in the compound, small amount of reacted titanium halide is on the surface of spherical particle and is activated by alkyl aluminum, alkyl aluminum reduces titanium halide from quadrivalent titanium to trivalent titanium to become active to initiate polymerization, and great amount of unreacted titanium halide is inside the particle.

In the present invention, after the above reaction, solid-liquid separation is further carried out. The solid-liquid separation mode is not particularly limited in the invention, and the solid-liquid separation mode is a conventional solid-liquid separation mode in the field, such as filtration and the like. In the present invention, it is preferable to further perform drying after the solid-liquid separation. The drying temperature is preferably 50-100 ℃; the solvent is sufficiently removed by solid-liquid separation and drying. Drying to obtain the main catalyst powder.

The main catalyst powder prepared by the invention can be directly used as an in-situ nucleating agent in propylene polymerization without being modified by a catalyst, is solid powder, does not contain any solvent, and unreacted vinyl compounds are also removed by drying, and can be directly added into a reactor or dispersed in white oil and added into the reactor in the propylene polymerization process.

The invention also provides the application of the catalyst in the technical scheme or the catalyst containing the main catalyst obtained by the preparation method as an in-situ nucleating agent in propylene polymerization.

wherein, the catalyst is the catalyst in the technical scheme or the catalyst containing the main catalyst obtained by the preparation method.

Regarding step S1:

the mixing is preferably: propylene monomer, cocatalyst, external electron donor and main catalyst are added into a polymerization reactor in sequence. Wherein the molar ratio of the propylene monomer to the titanium halide in the main catalyst is preferably (1X 10)⁵～1×10⁶) 1: 1. The dosage relationship of the cocatalyst, the external electron donor and the main catalyst is the same as that in the above technical scheme, and is not repeated here.

The temperature of the prepolymerization reaction is preferably 0-50 ℃, and specifically can be 0 ℃, 5 ℃, 10 ℃, 15 ℃, 20 ℃, 25 ℃, 30 ℃, 35 ℃, 40 ℃, 45 ℃ and 50 ℃. The time of the prepolymerization is preferably less than or equal to 2 h.

Regarding step S2:

in step S2 of the present invention, propylene monomer is again added. Wherein, the mol ratio of the propylene monomer in the step S1 to the propylene monomer in the step S2 is preferably 1: 3 to (3-10), and specifically can be 1: 3, 1: 4, 1: 5, 1: 6, 1: 7, 1: 8, 1: 9 and 1: 10.

Hydrogen is also introduced in step S2 of the present invention. The pressure of the hydrogen is preferably 0.1-10 bar, and specifically may be 0.1bar, 1bar, 1.2bar, 2bar, 3bar, 4bar, 5bar, 6bar, 7bar, 8bar, 9bar, 10 bar.

The polymerization temperature in step S2 of the present invention is preferably 50-80 deg.C, and specifically 50 deg.C, 55 deg.C, 60 deg.C, 65 deg.C, 70 deg.C, 75 deg.C, 80 deg.C. The time of the polymerization reaction is preferably 1-5 h, and specifically can be 1h, 2h, 3h, 4h and 5 h. After the polymerization reaction, the polypropylene is obtained.

In the step S1, a cocatalyst, an external electron donor and a main catalyst are sequentially added into a polymerization reactor containing a small amount of propylene monomer to initiate propylene prepolymerization, then a large amount of propylene monomer is added and hydrogen is filled, and an active center initiates monomer polymerization to synthesize in-situ nucleated polypropylene, wherein the concentration of the polymer alpha nucleating agent is 10-400 ppm, the crystallinity of the obtained polypropylene is more than 55%, and the crystallization temperature is more than 128 ℃.

The invention has the following beneficial effects:

the main catalyst powder prepared by the invention can be directly used as an in-situ nucleating agent in propylene polymerization without being modified by a catalyst, is solid powder, does not contain any solvent, and unreacted vinyl compounds are removed by drying, can be directly added into a reactor or dispersed in white oil to be added into the reactor in the propylene polymerization process to initiate propylene monomers to polymerize and synthesize in-situ nucleated polypropylene, and can obtain the polypropylene with high crystallinity and high crystallization temperature, wherein the crystallinity of the obtained polypropylene is more than 55 percent, and the crystallization temperature is more than 128 ℃.

For a further understanding of the present invention, reference will now be made to the following preferred embodiments of the invention in conjunction with the examples, but it is to be understood that the description is intended to further illustrate the features and advantages of the invention and is not intended to limit the scope of the claims which follow.

Example 1

a) Under argon atmosphere, 9.5g (0.1mol) of anhydrous magnesium chloride, 60mL of decane and 25mL of isopropanol are sequentially added into a three-necked flask and reacted at 90 ℃ for 3 hours to prepare a transparent magnesium chloride alcoholic compound solution.

b) The above magnesium chloride alcoholate solution is cooled to-20 ℃ and 300mL of cold (-20 ℃) TiCl are added₄And slowly stirring for 1h at the constant temperature of-20 ℃ to obtain a mixed solution 1.

c) Slowly heating the mixed solution 1 to 20 ℃, and adding 0.02mol of an internal electron donor (2-isopropyl-2-isoamyl-1, 3-dimethoxypropane) to obtain a mixed solution 2.

d) Heating the mixed solution 2 to 130 deg.C for 90min, standing for 60min, and adding 300mL TiCl₄And reacting for 2 hours at the temperature of 130 ℃ to obtain a mixed solution 3.

e) The mixture 3 was filtered and the solid isolate was washed 6 times with 300mL of 50 ℃ n-hexane to give a spherical solid 4.

f) Adding 150mL of n-hexane and 2mL of triethylaluminum (1M) into a reactor, adding the spherical solid 4 after 20min, reacting at 30 ℃ for 0.2h, adding 18g of vinylcyclohexane, heating to 50 ℃ for 50min, preserving heat, reacting for 10h, cooling to room temperature, filtering and drying to obtain 26.5g of main catalyst powder.

Example 2

The procedure is as in example 1, except that in step f), the temperature is raised to 40 ℃ and the reaction time is maintained for 13 h. 26.9g of procatalyst powder was obtained.

Example 3

The procedure is as in example 1, except that in step f), the reaction is incubated for a prolonged period of 15h after heating to 50 ℃. 27g of procatalyst powder was obtained.

Example 4

The procedure is as in example 1, except that, in step c), the internal electron donor (2, 2-diisobutyl-1, 3-dimethoxypropane) is added in an amount of likewise 0.02 mol. 26.7g of procatalyst powder was obtained.

Example 5

Example 1 was carried out, except that in step c) the internal electron donor was added (diethyl 2, 3-diisopropylsuccinate), again in an amount of 0.02 mol. 26.8g of procatalyst powder was obtained.

Example 6

The procedure is as in example 1, except that in step f) 9g of vinylcyclohexane are used. 18g of procatalyst powder was obtained.

Example 7

The procedure is as in example 1, except that 27g of vinylcyclohexane are used in step f). 32g of procatalyst powder was obtained.

Example 8

Carried out as in example 1, except that in step f), n-hexane was replaced by an equal amount of n-heptane. 26.2g of procatalyst powder was obtained.

Comparative example 1

The procedure is as in example 1, except that instead of step f), the spherical solid 4 obtained in step e) is dried (24 h at 80 ℃) and the dried product is used as procatalyst (9 g total) as a procatalyst for Z-N catalysts (Ti content 2.3 wt%).

Comparative example 2

S1, preparation of a main catalyst: as in comparative example 1.

S2, vacant: the material obtained after drying in step S1 was allowed to stand at room temperature for 24 hours.

S3, VCH modified main catalyst:

adding 150mL of n-hexane and 2mL of triethylaluminum (1M) into a reactor, after 20min, adding 9g of the main catalyst obtained in the step S2 after being left vacant, reacting at 30 ℃ for 1h, then adding 18g of vinylcyclohexane, heating to 50 ℃ within 50min, keeping the temperature, reacting for 10h, then cooling to room temperature, and drying the modified main catalyst component to obtain 24g of modified main catalyst.

Example 9: catalyzed propylene polymerization and product testing

1. Polymerization of propylene

After a 3L autoclave is fully replaced by high-purity nitrogen, 100g of propylene monomer, 1mL of triethylaluminum (1M) cocatalyst, 1mL of dicyclopentyldimethoxysilane (ED, 0.2M) as an external electron donor and a main catalyst with a certain titanium content (wherein the main catalyst contains 0.01mol of titanium, the molar ratio of Al in the cocatalyst to Ti in the main catalyst is 100, and the molar ratio of the external electron donor ED to Ti in the main catalyst is 20) are sequentially added, polymerization is carried out at 20 ℃ for 5min, then the temperature is raised to 70 ℃, 500g of propylene monomer and 1.2bar of hydrogen are added, and polymerization is carried out for 1h to obtain the polypropylene.

The main catalysts obtained in examples 1-2 and comparative examples 1-2 were polymerized with propylene according to the above polymerization process, and the amounts of the main catalysts were 0.051g, 0.050g, 0.034g, 0.060g, 0.049g, 0.020g, and 0.057g, which were controlled to ensure that the titanium content in all the main catalysts was 0.01 mol.

2. Testing of catalysts and testing of polymers

(1) The tests relating to the catalyst were as follows:

the Ti content of the catalyst is measured by an ultraviolet spectrophotometer.

The content of Polyvinylcyclohexane (PVCH) in the catalyst is calculated by measuring the conversion of Vinylcyclohexane (VCH). The amount of residual VCH in the catalyst/n-hexane mixture before drying was analyzed by gas chromatography. Toluene was used as internal standard.

(2) The tests on the polymers are as follows:

melt Mass Flow Rate (MFR): measured according to GB/T3682.1-2018, the load is 2.16kg, and the test temperature is 230 ℃.

Ii, isotacticity (C7-ins): measured by n-heptane extraction (boiling extraction of n-heptane for 8 h): a2 g dried polymer sample is put into a Soxhlet extractor to be extracted by boiling n-heptane for 8h, and the ratio of the polymer mass (g) to the 2(g) obtained by drying the residue to constant weight is the isotacticity.

DSC test: under the nitrogen atmosphere, firstly heating a 5-10 mg sample from room temperature to 200 ℃ at a speed of 10 ℃/min, and keeping the temperature at 200 ℃ for 5min to eliminate the thermal history; then, the sample was cooled to room temperature at a rate of-10 ℃/min; finally, the sample was reheated to 200 ℃ at a rate of 10 ℃/min. The crystallization temperature (T) of the sample was calculated using the second temperature rise curve according to the following relation_c) And degree of crystallinity (X)_c) Melting point (T)_m) Also measured according to the secondary heating curve: xc (%)

＝ΔH_m/ΔH^* _f100% of, wherein,. DELTA.H_mIs the melting enthalpy, Δ H, of the secondary heating curve^* _fIs the standard enthalpy of fusion for polypropylene (165.5J/g).

Iv, catalytic activity: calculated according to the following formula: CA ═ Q/W_Ti·t×10^-3With the unit of kgPP (gTi. h)^-1(ii) a Wherein CA is the catalytic activity of the catalyst, Q is the mass (g) of the product in the polymerization reaction, W_TiThe amount (g) of the catalyst titanium and t is the polymerization time (h).

The test results are shown in Table 1.

Table 1: preparation characterization of catalyst and propylene polymerization result

Note: VCH/Cat in comparative example 2 represents the ratio of the amount of VCH used in preparing the modified catalyst to the mass of the main catalyst; VCH/Cat in examples 1 to 8 represents the ratio of the amount of VCH used in the preparation of the procatalyst to the mass of the other components of the procatalyst. ID refers to an internal electron donor, D1 is 2-isopropyl-2-isoamyl-1, 3-dimethoxypropane, D2 is 2, 2-diisobutyl-1, 3-dimethoxypropane, and D3 is diethyl 2, 3-diisopropylsuccinate. The VCH polymerization in example 8 was carried out using n-heptane as solvent and n-hexane as solvent.

The catalytic activity is one of the important properties of the catalyst, and the catalytic activity represents the quality of the polymer which can be produced per unit amount of active component of the catalyst in a unit time, and directly influences the production cost of the product. As can be seen from Table 1, comparative example 2 using a VCH-modified catalyst and examples 1 to 8, which were prepared at one time and contain a polymer alpha nucleating agent, exhibited a different and excessive decrease in catalytic activity compared to comparative example 1, wherein the catalytic activity in comparative example 2 decreased by 6.5%, while the catalytic activity in examples 1 to 8, which were prepared by the method of the present invention, was decreased by only 0.8% to 5.1%, exhibiting better catalytic activity.

The crystallization temperature is a good indicator of the efficiency of the nucleating agent, a higher crystallization temperature means a more efficient nucleation in the final product. As can be seen from Table 1, examples 1 to 8 and comparative example 2 both show good nucleation effect, and the crystallization temperature of polypropylene is increased from 119 ℃ to 128.1 to 129.5 ℃; however, example 1 and comparative example 2 showed different VCH conversions at the same VCH polymerization time, the VCH polymerization efficiency of the process of the invention was higher, reaching 96.7% conversion of only 10 h; in addition, the example 1 and the example 2 show similar nucleation effect under different VCH conversion rates, and can be laterally reacted, and the preparation method of the invention can completely eliminate the influence of unreacted VCH on propylene polymerization. In addition, it can be seen that the crystallinity of polypropylene is obviously improved to more than 55% by the catalysts of examples 1 to 8 of the invention.

The foregoing examples are included merely to facilitate an understanding of the principles of the invention and their core concepts, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention. The scope of the invention is defined by the claims and may include other embodiments that occur to those skilled in the art. Such other embodiments are intended to be within the scope of the claims if they have structural elements that approximate the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims

1. A catalyst for in situ nucleating of polypropylene, wherein said catalyst comprises a procatalyst;

the main catalyst comprises:

wherein:

in formula (a):

R₃、R₄、R₅、R₆independently selected from: hydrogen, C₁～C₂₀Linear or branched alkyl, alkenyl, alkynyl, cycloalkyl, aryl, aralkyl or alkaryl groups; and R is₃～R₆Is not hydrogen at the same time;

in the formula (b):

the polymer alpha nucleating agent is a polyolefin-based compound.

2. The catalyst of claim 1, wherein the polymeric alpha nucleating agent is selected from at least one of polyvinylcyclohexane, polyvinylcyclopentane, polyvinyl-2-methylcyclohexane, poly-3-methyl-1-butene, poly-3-ethyl-1-hexene, poly-3-methyl-1-pentene and polystyrene.

3. The catalyst according to claim 1, wherein the titanium halide is at least one selected from the group consisting of titanium tetrachloride, titanium tetrabromide, and titanium tetraiodide;

4. The catalyst according to claim 1, wherein the succinate of formula (a) is selected from at least one of the following compounds:

5. The catalyst of claim 1, further comprising: cocatalyst and external electron donor;

the cocatalyst is an alkyl aluminum compound;

the external electron donor is a silane compound;

6. The catalyst of claim 5, wherein the co-catalyst is selected from at least one of triethylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, diethylaluminum monochloride, diisobutylaluminum monochloride, dihexylaluminum monochloride, and dioctylaluminum monochloride;

the external electron donor is selected from the group consisting of vinyltriethoxysilane, vinyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, diethyldimethoxysilane, dipropyldimethoxysilane, diisopropyldimethoxysilane, dibutyldimethoxysilane, diisobutyldimethoxysilane, di-t-butyldimethoxysilane, di-t-hexyldimethoxysilane, diphenyldimethoxysilane, dicyclohexyldimethoxysilane, dicyclopentyldimethoxysilane, dimethyldiethoxysilane, diethyldiethoxysilane, dipropyldiethoxysilane, diisopropyldiethoxysilane, dibutyldiethoxysilane, diisobutyldiethoxysilane, di-t-butyldiethoxysilane, di-t-hexyldiethoxysilane, diphenyldiethoxysilane, dicyclohexyldiethoxysilane, di-t-butyldiethoxysilane, di-t-hexyldiethoxysilane, di-t-butyldiethoxysilane, di-t-hexyldiethoxysilane, di-hexyldiethoxysilane, dicyclohexyldiethoxysilane, di-hexyldiethoxysilane, di-n-t-butyltriethoxysilane, di-methoxysilane, di-t-butyldiethoxysilane, di-t-hexyldiethoxysilane, di-methoxysilane, di-t-butyldiethoxysilane, di-t-butyldiethoxysilane, di-t-butyldiethoxysilane, di-butyltrimethoxysilane, a monomer, a, At least one of dicyclopentyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, cyclopentylmethyl-dimethoxysilane, cyclopentyltrimethoxysilane, cyclohexylmethyldimethoxysilane, cyclohexyltrimethoxysilane, t-hexyltrimethoxysilane, t-butyltrimethoxysilane and t-hexyltrimethoxysilane.

7. A method for preparing a catalyst for in situ nucleated polypropylene according to any one of claims 1 to 6 comprising the steps of:

8. The method of claim 7, wherein in step a):

the organic solvent is decane;

the alcohol compound is at least one selected from ethanol, n-propanol, isopropanol, n-butanol, isobutanol, pentanol, isoamylol and higher fatty alcohol with the carbon number of more than 6;

the reaction temperature is 80-150 ℃, and the reaction time is 0.5-5 h;

the step b) specifically comprises the following steps:

wherein the temperature of the cold titanium halide is-25 to 0 ℃.

9. The method of claim 7, wherein in step c):

the mixing temperature is 0-50 ℃;

in the step d):

the reaction temperature is 80-130 ℃, and the reaction time is 2-5 h;

in step f):

the mass ratio of the alkyl aluminum to the solid 4 is (0.01-1) to 1;

the volume ratio of the alkane solvent to the alkyl aluminum is (50-200) to 1;

the mass ratio of the vinyl compound to the solid 4 is (0.1-15) to 1;

the step f) specifically comprises the following steps:

10. The method of manufacturing according to claim 7 or 9, wherein in step f):

the alkane solvent is selected from at least one of n-pentane, isopentane, n-hexane, and n-heptane.

11. Use of the catalyst of any one of claims 1 to 6 or the catalyst containing the procatalyst prepared by the preparation method of any one of claims 7 to 11 as an in-situ nucleating agent in propylene polymerization.

12. A method for preparing in-situ nucleated polypropylene, which is characterized by comprising the following steps:

s2, adding propylene monomers and hydrogen into the system, and carrying out polymerization reaction to obtain polypropylene;

wherein the catalyst is the catalyst as defined in any one of claims 1 to 6 or the catalyst containing the main catalyst obtained by the preparation method as defined in any one of claims 7 to 11.

13. The method according to claim 12, wherein in the step S1, the temperature of the prepolymerization is 0-50 ℃ and the time is less than or equal to 2 h;

in step S2:

the polymerization reaction is carried out at the temperature of 50-80 ℃ for 1-5 h;

the pressure of the hydrogen is 0.1-10 bar;