Ethylene-propylene binary copolymer with high melt strength as well as preparation method and application of ethylene-propylene binary copolymer

Abstract

The invention provides a high-melt-strength ethylene-propylene binary copolymer as well as a preparation method and application thereof, and belongs to the technical field of olefin polymerization. According to the present invention, the specific catalyst component containing the cyanic acid ester internal electron donor compound is used, the silane external electron donor compound and the cyanic acid ester external electron donor compound are added to be compounded for use to form the unique catalyst system, and the specific preparation process is matched, such that the obtained ethylene-propylene biopolymer has wide molecular weight distribution, and supermolecules with a relatively high proportion. The method provided by the invention is simple, is easy for industrial production, can be used for preparing high-performance products, and has a wide application prospect.

Description

Technical Field

[0001] The invention relates to an ethylene-propylene binary copolymer with high melt strength and a preparation method and application thereof, belonging to the technical field of olefin polymerization. Background Art

[0002] High melt strength polypropylene (HMSPP) refers to the requirement of a higher tensile force when the melt is stretched and fractured. Improving the melt strength of general-purpose polypropylene has always been a hot topic in this field of research, and it is also a technical bottleneck for the expansion of polypropylene application areas and high performance. High melt strength polypropylene can be used in thermoforming processing to demold parts at a higher temperature, shorten the molding cycle, and increase production; it can resist the rupture of micropore walls during foaming, increase the foaming ratio, reduce density, and increase the closed cell rate; it exhibits a faster coating speed and very small necking during extrusion coating. Therefore, high melt strength polypropylene is the research focus of polypropylene production technology innovation.

[0003] Conventional methods for improving the melt strength of polypropylene mainly include polymerization technology, reactive extrusion and irradiation modification. The reactive extrusion method prepares high melt strength polypropylene by adding peroxide and other multifunctional reactive monomers to polypropylene. That is, peroxide and a third monomer are added to polypropylene powder, and long-chain branched polypropylene is generated after reaction, thereby improving the melt strength of polypropylene. The reactive extrusion method must add a variety of chemical components to produce high melt strength polypropylene, which increases production costs on the one hand, and also causes fluctuations in product quality due to the control of the amount added. More importantly, the long-term presence of additives in the polymer will lead to a gradual deterioration of the yellow index and physical properties of the product. Some added compounds are still toxic and cannot be used for contact with food or medicine. Many research institutions at home and abroad use this method to produce high melt strength polypropylene with a long-chain branch structure. Irradiation modification is to select a suitable radiation source and dose to irradiate polypropylene, so that the polypropylene molecular chain is cross-linked to produce a long-chain branch structure, thereby improving the melt strength of polypropylene. In terms of the selection of radiation sources, electron rays generated by electron accelerators or gamma rays generated by 60Co are currently mainly used.

[0004] The polymerization technology currently includes one-step method, two-step method, copolymerization method and in-situ polymerization method. The foreign patent technology is based on Chisso's US 6225432B1 using CGC (constrained geometry catalysts) constrained geometry catalysts to branch the polymer long chain; Chinese invention patents CN200710179266.7 and CN 201010147765.X respectively graft copolymerize propylene with α, ω-non-conjugated diene, styrene and substituted styrene monomers (T-type monomers) to form long chain branches. The polymerization technology method can accurately control the length of the branch chain and the distribution of the branch structure in the polymer main chain. In the industry of preparing high melt strength polypropylene with Ziegler-Natta catalyst, other monomers are introduced, or more reactors are added while changing the types of materials in different reactors, which increases the reaction raw materials, increases the processing steps such as recovery and purification, and the process is cumbersome. The practicality of constructing long chain branched structures based on metallocene catalyst systems currently needs to be improved.

[0005] In summary, it is very necessary to develop a high-performance, economical, and environmentally friendly high melt strength polypropylene production technology. Among them, the catalyst in-situ generation method is the most applicable, environmentally friendly, simple, and most stable industrial production method. This method is to prepare a wide molecular weight distribution polypropylene in a reactor by using a specific catalyst to achieve high melt strength of the final polymer. It is usually to selectively add external electron donors with different hydrogen sensitivity at different polymerization stages, and to adjust the molecular weight by adjusting the hydrogen concentration in different reactors, thereby realizing the preparation of polypropylene containing both high molecular weight fractions and low molecular weight fractions, wherein the high molecular weight fraction ensures the melt strength of the final polymer, and the broadened molecular weight distribution ensures its good processing performance. Summary of the invention

[0006] In order to solve the deficiencies in the prior art, the present invention provides an ethylene-propylene copolymer with high melt strength and a preparation method and application thereof through in-depth research. The present invention adopts a Ziegler-Natta catalyst component containing an internal electron donor of cyanoesters. When forming the catalyst, a unique catalyst system is formed by a reasonable compounding of two different types of external electron donors, silanes and cyanoesters. The method of direct polymerization in the reactor obtains a copolymer with wide M z+1 / M n The ethylene-propylene copolymer has a high molecular weight distribution and contains a large number of ultra-high molecular weight fractions. The polymer has high melt strength.

[0007] The present invention provides an ethylene-propylene copolymer with high melt strength, wherein the molecular weight distribution M of the ethylene-propylene copolymer is z+1 / M nThe melting point is 70~180, and the melt strength is 0.18~0.80N.

[0008] Optionally, the molecular weight Mw of the ethylene-propylene copolymer is greater than 5 million and accounts for ≥ 0.3%.

[0009] The present invention also provides a method for preparing an ethylene-propylene binary copolymer with high melt strength, wherein ethylene and propylene are contacted with a catalyst system under olefin polymerization conditions to react and generate the ethylene-propylene binary copolymer;

[0010] The catalyst system comprises the following components and reaction products thereof:

[0011] A, a catalyst component; the catalyst component comprises titanium and a cyanoester internal electron-donating compound;

[0012] B. Organoaluminum compounds;

[0013] C. External electron donor compounds; the external electron donor compounds include silane external electron donor compounds and cyanate external electron donor compounds.

[0014] Optionally, the catalyst component, the organoaluminum compound and the external electron donor compound are pre-contacted before contacting ethylene and propylene; the pre-contact time is 0.1 to 60 minutes, preferably 1 to 40 minutes; the pre-contact temperature is -20°C to 80°C, preferably 0°C to 60°C.

[0015] Optionally, the catalyst component, the organoaluminum compound and the silane external electron donor compound are first pre-contacted, and then pre-contacted with the cyanate external electron donor compound.

[0016] Optionally, the catalyst system is first prepolymerized to a certain extent in the presence of a small amount of ethylene and propylene to obtain a prepolymerized catalyst, and then the prepolymerized catalyst is further contacted with ethylene and propylene to react to obtain an ethylene-propylene copolymer; the prepolymerization ratio is 1 to 1000 g polymer / g catalyst, preferably 2 to 500 g polymer / g catalyst; the prepolymerization temperature is -20°C to 80°C, preferably 0°C to 50°C.

[0017] Optionally, the polymerization conditions include: polymerization temperature of 0°C to 100°C, preferably 30°C to 90°C, and time of 20 to 600 min, preferably 30 to 500 min.

[0018] Optionally, the Ziegler-Natta catalyst component in which the internal electron donor used in the present invention is a cyano ester, contains, based on the total weight of the catalyst component, 1.0 wt% to 5.0 wt% of element titanium and 3.0 wt% to 20.0 wt% of cyano ester internal electron donor compounds; more preferably, based on the total weight of the catalyst component, it contains 1.3 wt% to 4.0 wt% of element titanium and 5 wt% to 15 wt% of cyano ester internal electron donor compounds.

[0019] Optionally, the cyanoester internal electron donor compound has a structure represented by general formula (I):

[0020]

[0021] Among them, R 1 and R 2 R is independently selected from a linear C1-C4 alkyl group and a branched C1-C4 alkyl group; 3 and R 4 Independently selected from C3-C6 isoalkyl, C3-C6 secondary alkyl and C3-C6 cycloalkyl.

[0022] Optionally, the cyano ester internal electron donor compound is selected from cyanosuccinate compounds, preferably 2,3-dinon-linear alkyl-2-cyanosuccinate diester compounds, more preferably 2,3-diisopropyl-2-dicyanosuccinic acid dimethyl ester, 2,3-diisopropyl-2-dicyanosuccinic acid diethyl ester, 2,3-diisopropyl-2-dicyanosuccinic acid di-n-propyl ester, 2,3-diisopropyl-2-dicyanosuccinic acid di-isopropyl ester, 2,3-diisopropyl-2-dicyanosuccinic acid di-n-butyl ester, 2,3-diisopropyl-2-dicyanosuccinic acid di-isobutyl ester, 2,3-diisopropyl-2-dicyanosuccinic acid-1-methyl-4-ethyl ester (R 1 = methyl, R 2 =ethyl), 2,3-diisopropyl-2-cyanosuccinic acid-1-ethyl ester-4-methyl ester (R 1 =Ethyl, R 2 = methyl), 2,3-diisopropyl-2-cyanosuccinic acid-1-n-butyl-4-ethyl ester (R 1 = n-butyl, R 2 =ethyl), 2,3-diisopropyl-2-cyanosuccinic acid-1-ethyl ester-4-n-butyl ester (R 1 =Ethyl, R 2=n-butyl), dimethyl 2,3-diisobutyl-2-dicyanosuccinate, diethyl 2,3-diisobutyl-2-dicyanosuccinate, di-n-propyl 2,3-diisobutyl-2-dicyanosuccinate, diisopropyl 2,3-diisobutyl-2-dicyanosuccinate, di-n-butyl 2,3-diisobutyl-2-dicyanosuccinate, diisobutyl 2,3-diisobutyl-2-dicyanosuccinate, 1-methyl-4-ethyl 2,3-diisobutyl-2-cyanosuccinate (R 1 = methyl, R 2 =ethyl), 2,3-diisobutyl-2-cyanosuccinic acid-1-ethyl ester-4-methyl ester (R 1 =Ethyl, R 2 = methyl), 2,3-diisobutyl-2-cyanosuccinic acid-1-n-butyl-4-ethyl ester (R 1 = n-butyl, R 2 =ethyl), 2,3-diisobutyl-2-cyanosuccinic acid-1-ethyl ester-4-n-butyl ester (R 1 =Ethyl, R 2 =n-butyl), dimethyl 2,3-di-sec-butyl-2-dicyanosuccinate, diethyl 2,3-di-sec-butyl-2-dicyanosuccinate, di-n-propyl 2,3-di-sec-butyl-2-dicyanosuccinate, diisopropyl 2,3-di-sec-butyl-2-dicyanosuccinate, di-n-butyl 2,3-di-sec-butyl-2-dicyanosuccinate, diisobutyl 2,3-di-sec-butyl-2-dicyanosuccinate, 1-methyl-4-ethyl 2,3-di-sec-butyl-2-cyanosuccinate (R 1 = methyl, R 2 =ethyl), 2,3-di-sec-butyl-2-cyanosuccinic acid-1-ethyl-4-methyl ester (R 1 =Ethyl, R 2 = methyl), 2,3-di-sec-butyl-2-cyanosuccinic acid-1-n-butyl-4-ethyl ester (R 1 = n-butyl, R 2 =ethyl), 2,3-di-sec-butyl-2-cyanosuccinic acid-1-ethyl ester-4-n-butyl ester (R 1 =Ethyl, R 2 =n-butyl), dimethyl 2,3-dicyclopentyl-2-dicyanosuccinate, diethyl 2,3-dicyclopentyl-2-dicyanosuccinate, di-n-propyl 2,3-dicyclopentyl-2-dicyanosuccinate, diisopropyl 2,3-dicyclopentyl-2-dicyanosuccinate, di-n-butyl 2,3-dicyclopentyl-2-dicyanosuccinate, diisobutyl 2,3-dicyclopentyl-2-dicyanosuccinate, 1-methyl-4-ethyl 2,3-dicyclopentyl-2-cyanosuccinate (R 1 = methyl, R 2= ethyl), 1-ethyl-4-methyl 2,3-dicyclopentyl-2-cyanobutanedioate (R 1 = ethyl, R 2 = methyl), 1-butyl-4-ethyl 2,3-dicyclopentyl-2-cyanobutanedioate (R 1 = butyl, R 2 = ethyl), 1-ethyl-4-butyl 2,3-dicyclopentyl-2-cyanobutanedioate (R 1 = ethyl, R 2 = butyl), dimethyl 2,3-dicyclohexyl-2-dicyanobutanedioate, diethyl 2,3-dicyclohexyl-2-dicyanobutanedioate, dipropyl 2,3-dicyclohexyl-2-dicyanobutanedioate, diisopropyl 2,3-dicyclohexyl-2-dicyanobutanedioate, dibutyl 2,3-dicyclohexyl-2-dicyanobutanedioate, diisobutyl 2,3-dicyclohexyl-2-dicyanobutanedioate, 1-methyl-4-ethyl 2,3-dicyclohexyl-2-cyanobutanedioate (R 1 = methyl, R 2 = ethyl), 1-ethyl-4-methyl 2,3-dicyclohexyl-2-cyanobutanedioate (R 1 = ethyl, R 2 = methyl), 1-butyl-4-ethyl 2,3-dicyclohexyl-2-cyanobutanedioate (R 1 = butyl, R 2 = ethyl), 1-ethyl-4-butyl 2,3-dicyclohexyl-2-cyanobutanedioate (R 1 = ethyl, R 2 = butyl). Among them, diethyl 2,3-diisopropyl-2-dicyanobutanedioate, dipropyl 2,3-diisopropyl-2-dicyanobutanedioate, diisopropyl 2,3-diisopropyl-2-dicyanobutanedioate, dibutyl 2,3-diisopropyl-2-dicyanobutanedioate, diisobutyl 2,3-diisopropyl-2-dicyanobutanedioate are preferably at least one. The above electron donor compounds can be used alone or in combination of several.

[0023] Optionally, in the present invention, the 2,3-dialkyl-2-cyanobutanedioate compounds with non-linear alkyl groups are prepared by the method disclosed in International Patent Application No. PCT / CN2010 / 000202.

[0024] Optionally, the general formula of the organoaluminum compound is AlR n X 3-n , where R is hydrogen, a hydrocarbon group with 1 to 20 carbon atoms, X is a halogen, and n is an integer of 0 < n ≤ 3.

[0025] Optionally, the organoaluminum compound is selected from alkylaluminum halides such as trimethylaluminum, triethylaluminum, triisobutylaluminum, trioctylaluminum, diethylaluminum chloride, diisobutylaluminum chloride, diethylaluminum chloride, diisobutylaluminum chloride, and ethylaluminum dichloride, among which triethylaluminum and triisobutylaluminum are preferred.

[0026] Optionally, the ratio between the organic aluminum compound and the catalyst component is 5 to 5000, preferably 20 to 500, in terms of the molar ratio of aluminum element to titanium element.

[0027] Optionally, the silane external electron donor compound is selected from the general formula R1R2 m Si(OR3) 3-m 、R4 n Si(OR5) 4-n and R6R7Si(OR8)2, or a mixture of any two or more thereof in any proportion, wherein: m and n are independently integers of 0 to 2; R1 and R2 are independently C1 to C 10 A straight chain, branched or cyclic aliphatic group; R3, R4, R5, R6 and R8 are independently a C1-C3 straight chain aliphatic group; R7 is a C3-C6 branched or cyclic aliphatic group.

[0028] Optionally, specific examples of the silane-based external electron donor compound include but are not limited to tetramethoxysilane, n-propyltriethoxysilane, isobutyltriethoxysilane, isobutyltrimethoxysilane, vinyltrimethoxysilane, n-propyltrimethoxysilane, tetraethoxysilane, trimethylmethoxysilane, trimethylethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diisobutyldimethoxysilane, methylcyclohexyldimethoxysilane, methylisobutyldimethoxysilane, dicyclohexyldimethoxysilane, phenyltrimethoxysilane, dicyclopentyldimethoxysilane, and the like.

[0029] Optionally, the molar ratio of the organoaluminum compound to the silane external electron donor compound is 0.5:1 to 200:1, preferably 1:1 to 100:1, based on the molar ratio of aluminum element to silicon element.

[0030] Optionally, the cyanoester external electron donor compound has a structure represented by general formula (I):

[0031]

[0032] Among them, R 1 and R 2 The groups are independently selected from linear C1-C4 alkyl groups and branched C1-C4 alkyl groups; R 3 and R 4Independently selected from C3-C6 isoalkyl, C3-C6 secondary alkyl and C3-C6 cycloalkyl.

[0033] Optionally, the cyanoester external electron donor compound is selected from cyanosuccinate compounds, preferably 2,3-dinon-linear alkyl-2-cyanosuccinate diester compounds, and further preferably 2,3-diisopropyl-2-dicyanosuccinic acid dimethyl ester, 2,3-diisopropyl-2-dicyanosuccinic acid diethyl ester, 2,3-diisopropyl-2-dicyanosuccinic acid di-n-propyl ester, 2,3-diisopropyl-2-dicyanosuccinic acid di-isopropyl ester, 2,3-diisopropyl-2-dicyanosuccinic acid di-n-butyl ester, 2,3-diisopropyl-2-dicyanosuccinic acid di-isobutyl ester, 2,3-diisopropyl-2-dicyanosuccinic acid-1-methyl-4-ethyl ester (R 1 = methyl, R 2 =ethyl), 2,3-diisopropyl-2-cyanosuccinic acid-1-ethyl ester-4-methyl ester (R 1 =Ethyl, R 2 = methyl), 2,3-diisopropyl-2-cyanosuccinic acid-1-n-butyl-4-ethyl ester (R 1 = n-butyl, R 2 =ethyl), 2,3-diisopropyl-2-cyanosuccinic acid-1-ethyl ester-4-n-butyl ester (R 1 =Ethyl, R 2 =n-butyl), dimethyl 2,3-diisobutyl-2-dicyanosuccinate, diethyl 2,3-diisobutyl-2-dicyanosuccinate, di-n-propyl 2,3-diisobutyl-2-dicyanosuccinate, diisopropyl 2,3-diisobutyl-2-dicyanosuccinate, di-n-butyl 2,3-diisobutyl-2-dicyanosuccinate, diisobutyl 2,3-diisobutyl-2-dicyanosuccinate, 1-methyl-4-ethyl 2,3-diisobutyl-2-cyanosuccinate (R 1 = methyl, R 2 =ethyl), 2,3-diisobutyl-2-cyanosuccinic acid-1-ethyl ester-4-methyl ester (R 1 =Ethyl, R 2 = methyl), 2,3-diisobutyl-2-cyanosuccinic acid-1-n-butyl-4-ethyl ester (R 1 = n-butyl, R 2 =ethyl), 2,3-diisobutyl-2-cyanosuccinic acid-1-ethyl ester-4-n-butyl ester (R 1 =Ethyl, R 2=n-butyl), dimethyl 2,3-di-sec-butyl-2-dicyanosuccinate, diethyl 2,3-di-sec-butyl-2-dicyanosuccinate, di-n-propyl 2,3-di-sec-butyl-2-dicyanosuccinate, diisopropyl 2,3-di-sec-butyl-2-dicyanosuccinate, di-n-butyl 2,3-di-sec-butyl-2-dicyanosuccinate, diisobutyl 2,3-di-sec-butyl-2-dicyanosuccinate, 1-methyl-4-ethyl 2,3-di-sec-butyl-2-cyanosuccinate (R 1 = methyl, R 2 =ethyl), 2,3-di-sec-butyl-2-cyanosuccinic acid-1-ethyl-4-methyl ester (R 1 =Ethyl, R 2 = methyl), 2,3-di-sec-butyl-2-cyanosuccinic acid-1-n-butyl-4-ethyl ester (R 1 = n-butyl, R 2 =ethyl), 2,3-di-sec-butyl-2-cyanosuccinic acid-1-ethyl ester-4-n-butyl ester (R 1 =Ethyl, R 2 =n-butyl), dimethyl 2,3-dicyclopentyl-2-dicyanosuccinate, diethyl 2,3-dicyclopentyl-2-dicyanosuccinate, di-n-propyl 2,3-dicyclopentyl-2-dicyanosuccinate, diisopropyl 2,3-dicyclopentyl-2-dicyanosuccinate, di-n-butyl 2,3-dicyclopentyl-2-dicyanosuccinate, diisobutyl 2,3-dicyclopentyl-2-dicyanosuccinate, 1-methyl-4-ethyl 2,3-dicyclopentyl-2-cyanosuccinate (R 1 = methyl, R 2 =ethyl), 2,3-dicyclopentyl-2-cyanosuccinic acid-1-ethyl ester-4-methyl ester (R 1 =Ethyl, R 2 = methyl), 2,3-dicyclopentyl-2-cyanosuccinic acid-1-n-butyl-4-ethyl ester (R 1 = n-butyl, R 2 =ethyl), 2,3-dicyclopentyl-2-cyanosuccinic acid-1-ethyl ester-4-n-butyl ester (R 1 =Ethyl, R 2 =n-butyl), dimethyl 2,3-dicyclohexyl-2-dicyanosuccinate, diethyl 2,3-dicyclohexyl-2-dicyanosuccinate, di-n-propyl 2,3-dicyclohexyl-2-dicyanosuccinate, diisopropyl 2,3-dicyclohexyl-2-dicyanosuccinate, di-n-butyl 2,3-dicyclohexyl-2-dicyanosuccinate, diisobutyl 2,3-dicyclohexyl-2-dicyanosuccinate, 1-methyl-4-ethyl 2,3-dicyclohexyl-2-cyanosuccinate (R 1 = methyl, R 2=ethyl), 2,3-dicyclohexyl-2-cyanosuccinic acid-1-ethyl ester-4-methyl ester (R 1 =Ethyl, R 2 = methyl), 2,3-dicyclohexyl-2-cyanosuccinic acid-1-n-butyl-4-ethyl ester (R 1 = n-butyl, R 2 =ethyl), 2,3-dicyclohexyl-2-cyanosuccinic acid-1-ethyl ester-4-n-butyl ester (R 1 =Ethyl, R 2 =n-butyl). Among them, at least one of 2,3-diisopropyl-2-dicyanosuccinate diethyl ester, 2,3-diisopropyl-2-dicyanosuccinate di-n-propyl ester, 2,3-diisopropyl-2-dicyanosuccinate di-isopropyl ester, 2,3-diisopropyl-2-dicyanosuccinate di-n-butyl ester, and 2,3-diisopropyl-2-dicyanosuccinate di-isobutyl ester is preferred. The above-mentioned external electron donor compounds can be used alone or in combination.

[0034] Optionally, in the present invention, the 2,3-dinon-linear alkyl-2-cyanosuccinic acid diester compound is prepared according to the method disclosed in International Patent Application No. PCT / CN2010 / 000202.

[0035] Optionally, the molar ratio of the organoaluminum compound to the cyanate ester external electron donor compound is 0.5:1 to 100:1, preferably 1:1 to 50:1, based on the molar ratio of aluminum element to cyano group.

[0036] The preparation method of the ethylene-propylene copolymer provided by the present invention can also be used to copolymerize two or more other olefin monomers. The method comprises: under olefin polymerization conditions, contacting two or more olefin monomers with the catalyst system provided by the present invention, at least two of the olefin monomers are olefins represented by the general formula CH2=CHR, wherein R is hydrogen or a C1-C6 alkyl group. Specific examples of the olefin monomers include, but are not limited to, at least one of ethylene, propylene, 1-n-butene, 1-n-pentene, 1-n-hexene, 1-n-octene and 4-methyl-1-pentene. Preferably, the olefin monomer can be at least one of ethylene, propylene, 1-n-butene, 4-methyl-1-pentene and 1-n-hexene. More preferably, the olefin monomers are propylene and ethylene.

[0037] According to the present invention, the solid catalyst component, the organoaluminum compound as a co-catalyst and the external electron donor compound can be contacted before contacting the olefin monomer, which is called "pre-contact" or "pre-complexation" in the industry; or the three components can be added to the olefin monomer separately before the polymerization reaction, that is, no "pre-contact" is implemented. According to the olefin polymerization method provided by the present invention, it is preferred that the components in the olefin polymerization catalyst system adopt the "pre-contact" method. The time of "pre-contact" is 0.1 to 60 minutes, preferably 1 to 40 minutes; the temperature of "pre-contact" is -20°C to 80°C, preferably 0°C to 60°C.

[0038] The catalyst system is first polymerized to a certain extent in the presence of a small amount of olefin monomer to obtain a prepolymerized catalyst, and then the prepolymerized catalyst is further contacted with the olefin monomer to react to obtain an olefin polymer. This technology is called the "prepolymerization" process in the industry, which helps to improve the polymerization activity of the catalyst and the bulk density of the polymer. According to the olefin polymerization method provided by the present invention, the "prepolymerization" process can be adopted, or the "prepolymerization" process can not be adopted, and the "prepolymerization" process is preferably adopted. The "prepolymerization" ratio is 1 to 1000 g polymer / g catalyst when the olefin monomers are ethylene and propylene, preferably 2 to 500 g polymer / g catalyst; the temperature of the "prepolymerization" is -20°C to 80°C, preferably 0°C to 50°C.

[0039] According to the polymerization method for preparing polyolefin with high melt strength of the present invention, the polymerization conditions may be conventional conditions in the art, and the amount of catalyst used may be the amount of various catalysts used in the prior art.

[0040] The present invention also provides the above-mentioned ethylene-propylene binary copolymer with high melt strength and the use of the above-mentioned ethylene-propylene binary copolymer with high melt strength prepared by the above-mentioned preparation method in the fields of thermoforming, foaming, pipes, and plates. DETAILED DESCRIPTION

[0041] The present invention will be specifically described by way of examples, but the present invention is not limited to the following examples.

[0042] The test method involved in the present invention is as follows:

[0043] (1) Titanium content in catalyst: tested by 721 spectrophotometer.

[0044] (2) Melt index (MI) of polymer: measured according to the test standard GB / T3682-2000.

[0045] (3) Content of internal electron donor in catalyst component (cyanate content): measured by Waters 600E liquid chromatography.

[0046] (4) Activity: Catalyst activity = (mass of polyolefin produced) g / (mass of catalyst solid component) g.

[0047] (5) Polymer molecular weight distribution M z+1 / M n : PL-GPC220 was used with trichlorobenzene as solvent at 150°C (standard sample: polystyrene, flow rate: 1.0 ml / min, column: 3xPlgel 10um MlxED-B300x7.5nm).

[0048] (6) Melt strength: A Rheoten melt strength tester produced by Geottfert Werkstoff Pruefmaschinen of Germany was used. The instrument comprises a pair of rollers rotating in opposite directions. The polymer melt is extruded from a capillary and stretched vertically through the rollers. The stretching force can be measured by a measuring element.

[0049] Example 1

[0050] (1) Preparation of catalyst components

[0051] The catalyst component was prepared according to the method of patent CN201110021246.3, with a titanium content of 2.7% and a 2,3-diisopropyl-2-dicyanosuccinic acid diethyl ester (abbreviated as "JS1") content of 13.25%.

[0052] (2) Olefin polymerization

[0053] Using propylene and ethylene as olefin monomers, the polymerization was carried out according to the following steps:

[0054] In a 5-liter stainless steel autoclave equipped with a stirrer, after replacing with nitrogen, 5 ml of a hexane solution of triethylaluminum (the concentration of triethylaluminum is 0.5 mmol / ml), 1.0 ml of a hexane solution of cyclohexylmethyldimethoxysilane (CHMMS) (the concentration of CHMMS is 0.10 mmol / ml), 10 ml of anhydrous hexane and 10 mg of a solid catalyst component were introduced in a nitrogen stream at room temperature, and after pre-contacting at 12°C for 8 minutes, 1.6 ml of a hexane solution of a second external electron donor JS1 (the concentration of JS1 is 0.05 mmol / ml) was added, and after pre-contacting at 10°C for 5 minutes, the autoclave was closed, 0.05 mol of hydrogen, 5 mol of propylene and 0.5 mol of ethylene were introduced, stirring was started, and after pre-polymerization at 20°C for 20 minutes, 0.3 mol of hydrogen, 15 mol of propylene and 3.0 mol of ethylene were introduced, and the temperature was raised to 70°C within 10 minutes. After the polymerization reaction was carried out at 70°C for 2 hours, stirring was stopped, unpolymerized hydrogen, propylene and ethylene monomers were removed, and the polymer was collected.

[0055] Example 2

[0056] (1) Preparation of catalyst components

[0057] Same as Example 1.

[0058] (2) Olefin polymerization

[0059] The same procedures as in Example 1 are followed except that cyclohexylmethyldimethoxysilane (CHMMS) is replaced by 2,2-diisobutyl-1,3-dimethoxysilane (DIBMP).

[0060] Example 3

[0061] (1) Preparation of catalyst components

[0062] Same as Example 1.

[0063] (2) Olefin polymerization

[0064] The same procedures as in Example 1 were followed except that the hexane solution of cyclohexylmethyldimethoxysilane (CHMMS) was changed from 1.0 ml to 2.0 ml.

[0065] Example 4

[0066] (1) Preparation of catalyst components

[0067] Same as Example 1.

[0068] (2) Olefin polymerization

[0069] The same procedures as in Example 1 were followed except that the hexane solution of JS1 was changed from 1.6 ml to 3.2 ml.

[0070] Example 5

[0071] (1) Preparation of catalyst components

[0072] Same as Example 1.

[0073] (2) Olefin polymerization

[0074] The same procedures as in Example 1 were followed except that the hexane solution of JS1 was changed from 1.6 ml to 0.8 ml.

[0075] Example 6

[0076] (1) Preparation of catalyst components

[0077] Same as Example 1.

[0078] (2) Olefin polymerization

[0079] The process is the same as in Example 1 except that “introducing 0.05 mol of hydrogen, 5 mol of propylene and 0.5 mol of ethylene” and “introducing 0.3 mol of hydrogen, 15 mol of propylene and 3.0 mol of ethylene” are changed to “introducing 0.05 mol of hydrogen, 8 mol of propylene and 0.8 mol of ethylene” and “introducing 0.3 mol of hydrogen, 12 mol of propylene and 5.0 mol of ethylene”.

[0080] Example 7

[0081] (1) Preparation of catalyst components

[0082] Same as Example 1.

[0083] (2) Olefin polymerization

[0084] The same as Example 1 except that “introducing 0.05 mol of hydrogen, 5 mol of propylene and 0.5 mol of ethylene” and “introducing 0.3 mol of hydrogen, 15 mol of propylene and 3.0 mol of ethylene” are changed to “introducing 0.03 mol of hydrogen, 3 mol of propylene and 0.3 mol of ethylene” and “introducing 0.32 mol of hydrogen, 17 mol of propylene and 3.2 mol of ethylene”.

[0085] Example 8

[0086] (1) Preparation of catalyst components

[0087] Same as Example 1.

[0088] (2) Olefin polymerization

[0089] The same as in Example 1 except that "prepolymerization at 20°C for 20 min" is changed to "prepolymerization at 15°C for 5 min".

[0090] Comparative Example 1

[0091] (1) Preparation of catalyst components

[0092] Take 10g of alkoxymagnesium of the same specification as in Example 1, 50ml of toluene, and 2.5ml of di-n-butyl phthalate (abbreviated as "DNBP") to prepare a suspension; add 10ml of toluene and 90ml of titanium tetrachloride to a 300ml reactor that has been repeatedly replaced with high-purity nitrogen, heat it to 80°C, then add the prepared suspension to the reactor, keep it at this temperature for 1 hour, continue to heat it to 112°C, keep it at this temperature for 2 hours, and then filter the liquid clean. Then add 120ml of toluene and 30ml of titanium tetrachloride to a mixed solution, heat it to 110°C, stir it for 1 hour, do this 3 times, filter out the liquid, wash the resulting solid with 150ml of hexane 4 times, filter out the liquid and dry it to obtain a solid catalyst component. Titanium content 2.5%, di-n-butyl phthalate content 13.89%.

[0093] (2) Olefin polymerization

[0094] Using propylene and ethylene as olefins, the polymerization was carried out according to the following steps:

[0095] In a 5-liter stainless steel autoclave with a stirrer, after replacing with nitrogen, 5 ml of a hexane solution of triethylaluminum (the concentration of triethylaluminum is 0.5 mmol / ml), 1.0 ml of a hexane solution of cyclohexylmethyldimethoxysilane (CHMMS) (the concentration of CHMMS is 0.10 mmol / ml), 10 ml of anhydrous hexane and 10 mg of a solid catalyst component were introduced in a nitrogen stream at room temperature. The autoclave was closed, 0.35 mol of hydrogen, 20 mol of propylene and 3.5 mol of ethylene were introduced, stirring was started, and the temperature was raised to 70°C within 10 minutes. After polymerization reaction at 70°C for 2 hours, stirring was stopped, unpolymerized hydrogen, ethylene and propylene monomers were removed, and the polymer was collected.

[0096] Table 1 Electron donors of catalysts

[0097]

[0098]

[0099] Table 2 Aggregate data

[0100]

[0101] From the data comparison in the above table, it can be seen that the ethylene-propylene copolymer M obtained by using the catalyst system of the present invention z+1 / M n The molecular weight distribution is wide, there are many large molecules, and the melt strength is high.

[0102] In the present invention, a specific catalyst component containing a cyanate electron donor compound is used, and a silane external electron donor is added to cooperate with the cyanate external electron donor to form a unique catalyst system. In combination with a specific preparation process, the obtained ethylene-propylene copolymer has a wider molecular weight distribution and a higher proportion of ultra-large molecules. The ultra-high molecular weight fraction ensures its higher melt strength, and the wider M z+1 / M n The molecular weight distribution ensures good processing performance of the polymer. The method provided by the invention is simple, easy to industrialize, can prepare high-performance products, and has broad application prospects.

[0103] Any numerical value mentioned in the present invention, if there is only an interval of two units between any minimum value and any maximum value, includes all values ​​from the minimum value to the maximum value each time increasing by one unit. For example, if the amount of a component, or the value of a process variable such as temperature, pressure, time, etc. is declared to be 50-90, in this specification it means that 51-89, 52-88... and 69-71 and 70-71 are specifically listed. For non-integer values, 0.1, 0.01, 0.001 or 0.0001 can be appropriately considered as a unit. These are just some specially specified examples. In this application, in a similar manner, all possible combinations of numerical values ​​between the listed minimum and maximum values ​​are considered to have been disclosed.

[0104] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. An ethylene-propylene copolymer with high melt strength, characterized in that: The molecular weight distribution M of the ethylene-propylene copolymer z+1 / M n The melting point is 70~180, and the melt strength is 0.18~0.80N.

2. The ethylene-propylene copolymer according to claim 1, characterized in that: The molecular weight Mw of the ethylene-propylene copolymer is greater than 5 million, and the proportion is ≥0.3%.

3. A method for preparing a high melt strength ethylene-propylene copolymer, characterized in that: Under olefin polymerization conditions, ethylene and propylene are brought into contact with the catalyst system to react and form an ethylene-propylene copolymer; The catalyst system comprises the following components and reaction products thereof: A, a catalyst component; the catalyst component comprises titanium and a cyanoester internal electron-donating compound; B. Organoaluminum compounds; C. External electron donor compounds; the external electron donor compounds include silane external electron donor compounds and cyanate external electron donor compounds.

4. The preparation method according to claim 3, characterized in that: The catalyst component, the organoaluminum compound and the external electron donor compound are pre-contacted before contacting ethylene and propylene; the pre-contact time is 0.1 to 60 minutes, preferably 1 to 40 minutes; the pre-contact temperature is -20°C to 80°C, preferably 0°C to 60°C; Preferably, the catalyst component, the organoaluminum compound and the silane external electron donor compound are first pre-contacted, and then pre-contacted with the cyanate external electron donor compound; And / or, the catalyst system is first prepolymerized to a certain extent in the presence of a small amount of ethylene and propylene to obtain a prepolymerized catalyst, and then the prepolymerized catalyst is further contacted with ethylene and propylene to react to obtain an ethylene-propylene copolymer; the prepolymerization ratio is 1 to 1000 g polymer / g catalyst, preferably 2 to 500 g polymer / g catalyst; the prepolymerization temperature is -20°C to 80°C, preferably 0°C to 50°C.

5. The preparation method according to claim 3 or 4, characterized in that: The polymerization conditions include: polymerization temperature of 0°C to 100°C, preferably 30°C to 90°C, and time of 20 to 600 min, preferably 30 to 500 min.

6. The preparation method according to any one of claims 3 to 5, characterized in that: Based on the total weight of the catalyst component, it contains 1.0 wt% to 5.0 wt% of titanium element and 3.0 wt% to 20.0 wt% of cyanate internal electron donor compound; preferably, based on the total weight of the catalyst component, it contains 1.3 wt% to 4.0 wt% of titanium element and 5 wt% to 15 wt% of cyanate internal electron donor compound.

7. The preparation method according to any one of claims 3 to 6, characterized in that: The cyanate internal electron donor compound and the cyanate external electron donor compound are independently selected from compounds having a structure represented by general formula (I): Among them, R 1 and R 2 R is independently selected from a linear C1-C4 alkyl group and a branched C1-C4 alkyl group; 3 and R 4 Independently selected from C3-C6 isoalkyl, C3-C6 secondary alkyl and C3-C6 cycloalkyl; Preferably, the cyanate internal electron donor compound and the cyanate external electron donor compound are independently selected from cyanosuccinate compounds, and are further preferably 2,3-dinon-linear alkyl-2-cyanosuccinate diester compounds, more preferably 2,3-diisopropyl-2-dicyanosuccinic acid dimethyl ester, 2,3-diisopropyl-2-dicyanosuccinic acid diethyl ester, 2,3-diisopropyl-2-dicyanosuccinic acid di-n-propyl ester, 2,3-diisopropyl-2-dicyanosuccinic acid di-isopropyl ester, 2,3-diisopropyl-2-dicyanosuccinic acid di-n-butyl ester, 2,3-diisopropyl-2-dicyanosuccinic acid di-isobutyl ester, 2,3-diisopropyl-2-cyanosuccinic acid-1-methyl-4- ...isobutyl ester, 2,3-diisopropyl-2-dicyanosuccinic acid di-isobutyl ester, 2,3-diisopropyl-2-dicyanosuccinic acid di-isobutyl ester, 2,3-diisopropyl-2-dicyanosuccinic acid di-isopropyl Isopropyl-2-cyanosuccinic acid-1-ethyl-4-methyl ester, 2,3-diisopropyl-2-cyanosuccinic acid-1-n-butyl-4-ethyl ester, 2,3-diisopropyl-2-cyanosuccinic acid-1-ethyl-4-n-butyl ester, 2,3-diisobutyl-2-dicyanosuccinic acid-dimethyl ester, 2,3-diisobutyl-2-dicyanosuccinic acid-diethyl ester, 2,3- Diisobutyl-2-dicyanosuccinate di-n-propyl ester, 2,3-diisobutyl-2-dicyanosuccinate di-n-butyl ester, 2,3-diisobutyl-2-dicyanosuccinate di-n-butyl ester, 2,3-diisobutyl-2-dicyanosuccinate di-isobutyl ester, 2,3-diisobutyl-2-dicyanosuccinate-1-methyl-4-ethyl ester, 2,3-diisobutyl-2-cyano 1-Ethyl-4-Methyl Succinate, 2,3-Diisobutyl-2-Cyano-1-Butyl-4-Ethyl Succinate, 2,3-Diisobutyl-2-Cyano-1-Ethyl-4-N-Butyl Succinate, 2,3-Di-Sec-Butyl-2-Dicyanosuccinate Dimethyl Ester, 2,3-Di-Sec-Butyl-2-Dicyanosuccinate Diethyl Ester, 2,3-Di-Sec-Butyl-2-Dicyanosuccinate Di-n-propyl cyanobutanedioate, diisopropyl 2,3-di-sec-butyl-2-dicyanobutanedioate, di-n-butyl 2,3-di-sec-butyl-2-dicyanobutanedioate, diisobutyl 2,3-di-sec-butyl-2-dicyanobutanedioate, 1-methyl-4-ethyl 2,3-di-sec-butyl-2-cyanobutanedioate, 1-ethyl 2,3-di-sec-butyl-2-cyanobutanedioate -4-methyl ester, 2,3-di-sec-butyl-2-cyanosuccinic acid-1-n-butyl-4-ethyl ester, 2,3-di-sec-butyl-2-cyanosuccinic acid-1-ethyl-4-n-butyl ester, 2,3-dicyclopentyl-2-dicyanosuccinic acid dimethyl ester, 2,3-dicyclopentyl-2-dicyanosuccinic acid diethyl ester, 2,3-dicyclopentyl-2-dicyanosuccinic acid di-n-propyl Ester, 2,3-dicyclopentyl-2-dicyanosuccinic acid diisopropyl ester, 2,3-dicyclopentyl-2-dicyanosuccinic acid di-n-butyl ester, 2,3-dicyclopentyl-2-dicyanosuccinic acid diisobutyl ester, 2,3-dicyclopentyl-2-dicyanosuccinic acid 1-methyl-4-ethyl ester, 2,3-dicyclopentyl-2-cyano-succinic acid 1-ethyl-4-methyl ester, 2,3-Dicyclopentyl-2-cyanosuccinic acid-1-butyl-4-ethyl ester, 2,3-dicyclopentyl-2-cyanosuccinic acid-1-ethyl-4-butyl ester, 2,3-dicyclohexyl-2-dicyanosuccinic acid dimethyl ester, 2,3-dicyclohexyl-2-dicyanosuccinic acid diethyl ester, 2,3-dicyclohexyl-2-dicyanosuccinic acid di-n-propyl ester, 2,3-dicyclohexyl-2-dicyanosuccinic acid diisopropyl ester, 2,3-dicyclohexyl-2-dicyanosuccinic acid dimethyl ester, 2,3-dicyclohexyl-2-dicyanosuccinic acid diethyl ester, 2,3-dicyclohexyl-2-dicyanosuccinic acid di-n-propyl ester, 2,3-dicyclohexyl-2-dicyanosuccinic acid diisopropyl ester, 2,3-dicyclohexyl-2 - At least one of di-n-butyl dicyanobutanedioate, diisobutyl 2,3-dicyclohexyl-2-dicyanobutanedioate, 1-methyl-4-ethyl 2,3-dicyclohexyl-2-cyanobutanedioate, 1-ethyl-4-methyl 2,3-dicyclohexyl-2-cyanobutanedioate, 1-n-butyl-4-ethyl 2,3-dicyclohexyl-2-cyanobutanedioate, and 1-ethyl-4-n-butyl 2,3-dicyclohexyl-2-cyanobutanedioate.

8. The preparation method according to any one of claims 3 to 7, characterized in that: The general formula of the organoaluminum compound is AlR n X 3-n , where R is hydrogen, a hydrocarbon group with 1 to 20 carbon atoms, X is a halogen, and n is an integer where 0 < n ≤ 3; Preferably, the organoaluminum compound is at least one selected from trimethylaluminum, triethylaluminum, triisobutylaluminum, trioctylaluminum, diethylaluminum monochloride, diisobutylaluminum monochloride, diethylaluminum monochloride, diisobutylaluminum monochloride, and ethylaluminum dichloride; And / or, the silane external electron donor compound is selected from the general formula R1R2 m Si(OR3) 3-m 、R4 n Si(OR5) 4-n and R6R7Si(OR8)2, wherein m and n are independently integers of 0 to 2; R1 and R2 are independently C1 to C 10 A straight chain, branched or cyclic aliphatic group; R3, R4, R5, R6 and R8 are independently a C1-C3 straight chain aliphatic group; R7 is a C3-C6 branched or cyclic aliphatic group; Preferably, the silane-based external electron donor compound is selected from at least one of tetramethoxysilane, n-propyltriethoxysilane, isobutyltriethoxysilane, isobutyltrimethoxysilane, vinyltrimethoxysilane, n-propyltrimethoxysilane, tetraethoxysilane, trimethylmethoxysilane, trimethylethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diisobutyldimethoxysilane, methylcyclohexyldimethoxysilane, methylisobutyldimethoxysilane, dicyclohexyldimethoxysilane, phenyltrimethoxysilane, and dicyclopentyldimethoxysilane.

9. The preparation method according to any one of claims 3 to 8, characterized in that: The ratio between the organoaluminum compound and the catalyst component is 5 to 5000, preferably 20 to 500, in terms of the molar ratio of aluminum element to titanium element; And / or, the molar ratio of the organoaluminum compound to the silane-based external electron donor compound is 0.5:1 to 200:1, preferably 1:1 to 100:1, based on the molar ratio of aluminum element to silicon element; And / or, the molar ratio of the organoaluminum compound to the cyanate ester external electron donor compound is 0.5:1 to 100:1, preferably 1:1 to 50:1, based on the molar ratio of aluminum element to cyano group.

10. Use of an ethylene-propylene copolymer with high melt strength as claimed in claim 1 or 2, or an ethylene-propylene copolymer with high melt strength obtained by the preparation method as claimed in any one of claims 3 to 9 in the fields of thermoforming, foaming, pipes, and sheets.

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