CN105623075A

CN105623075A - Method for preparing impact-resistant polypropylene material with high melt strength

Info

Publication number: CN105623075A
Application number: CN201410602299.8A
Authority: CN
Inventors: 宋文波; 乔金樑; 张师军; 毕福勇; 郭梅芳; 尹华; 邹发生; 胡慧杰
Original assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Current assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Priority date: 2014-10-31
Filing date: 2014-10-31
Publication date: 2016-06-01
Anticipated expiration: 2034-10-31
Also published as: CN105623075B

Abstract

The invention provides a method for preparing an impact-resistant polypropylene material with high melt strength. The method comprises the steps of carrying out a homopolymerization reaction of propylene in the presence of a first propylene homopolymer so as to obtain a propylene homopolymer component containing the first propylene homopolymer and a second propylene homopolymer, and then, carrying out a copolymerization reaction of ethylene-1-butylene in the presence of the propylene homopolymer component so as to obtain the polypropylene material containing an ethylene-1-butylene copolymer. According to the method, a homopolymerized polypropylene continuous phase, which has a specific melt index, contains a large amount of ultrahigh-molecular-weight ingredients and is extremely wide in molecular weight distribution, is prepared through using external electron donors of different types and use levels, in combination with a chain transfer agent, i.e., hydrogen gas of different use levels separately at different polymerization stages, then, ethylene and 1-butylene copolymerization is further carried out so as to obtain a rubber phase dispersed in the continuous phase, and then, the impact-resistant polypropylene material with high melt strength, high rigidity and high toughness is obtained and is extensive in application.

Description

Preparation method of impact-resistant polypropylene material with high melt strength

Technical Field

The invention relates to a preparation method of a polypropylene material, in particular to a preparation method of an impact-resistant polypropylene material with high melt strength.

Background

The impact-resistant polypropylene has excellent high and low temperature impact strength, higher rigidity such as tensile strength, flexural modulus and the like and higher heat resistance temperature, and is widely applied to various fields such as molded or extruded automobile parts, household appliance parts, containers, household goods and the like. The impact polypropylene is generally used for injection processing due to low melt strength, and when the impact polypropylene is used for blow molding, the problems of unstable size of a mold blank, uneven thickness of a product and even no molding can be realized, and the like exist.

A common practice to increase the melt strength of polypropylene is to lower the melt index, i.e. increase the polypropylene molecular weight, but this can lead to difficulties in melting and extruding the material. Another method is to broaden the molecular weight distribution, for example, US7365136 and US6875826 report a method for preparing homo-and random-copolymerized polypropylene with wide molecular weight distribution and high melt strength, which selects alkoxysilane as an external electron donor (such as dicyclopentyldimethoxysilane), and regulates the molecular weight and distribution by adjusting the hydrogen concentration in a plurality of reactors connected in series, thereby achieving the effect of improving the melt strength of polypropylene. WO9426794 discloses a process for the production of high melt strength homo-and atactic polypropylene in multiple reactors in series by adjusting the hydrogen concentration in the different reactors to produce high melt strength polypropylene with a broad molecular weight distribution or bimodal distribution, the properties of the catalyst being not adjusted in the individual reactors, so that a large amount of hydrogen is required for the production process.

CN102134290 and CN102134291 disclose a preparation method of homo-polypropylene with wide molecular weight distribution and high melt strength, which adopts a plurality of reactors connected in series to prepare homo-polypropylene or random co-polypropylene with wide molecular weight and high melt strength by controlling the types and proportions of external electron donor components in different reaction stages and combining the control of hydrogen dosage of a molecular weight regulator.

The chinese application patent 201210422726.5 also reports a preparation method for obtaining homo-polypropylene or atactic polypropylene with wide molecular weight distribution and high melt strength by adjusting and controlling the isotactic index and hydrogen regulation sensitivity of the catalyst in different reactors through reasonable matching of two different types of external electron donors, namely silane and diether.

The above patents report methods for preparing homo-polypropylene or random co-polypropylene having high melt strength, that is, homo-polypropylene or random co-polypropylene prepared by these methods have insufficient rigidity, toughness or impact resistance in spite of having high melt strength, thereby limiting the applications of the obtained polypropylene. Therefore, it would be of great significance to provide an impact polypropylene having high melt strength, high rigidity and toughness with a rubber component and a dispersed phase structure of rubber, and a method for preparing the same.

Disclosure of Invention

The inventor of the invention has conducted extensive research and provides a method for preparing a high-melt-strength impact-resistant polypropylene material, and the polypropylene material prepared by the method has the characteristics of high rigidity and high toughness. The polypropylene material is an excellent material suitable for the fields of automobile parts, medical instruments, household articles and the like.

According to the present invention, there is provided a process for preparing a high melt strength impact polypropylene material as described above, comprising:

the first step is as follows: propylene homopolymerization comprising:

the first stage is as follows: carrying out a propylene homopolymerization reaction in the presence or absence of hydrogen under the action of a Ziegler-Natta catalyst containing a first external electron donor to obtain a reactant flow containing a first propylene homopolymer;

and a second stage: adding a second external electron donor to perform a complex reaction with a catalyst in the reactant flow, and then performing a propylene homopolymerization reaction in the presence of the first propylene homopolymer and hydrogen to generate a second propylene homopolymer, so as to obtain a propylene homopolymer component containing the first propylene homopolymer and the second propylene homopolymer; wherein,

the melt indices of the first propylene homopolymer and the propylene homopolymer component, measured at 230 ℃ under a load of 2.16kg, are 0.001-0.4g/10min and 0.1-15g/10min, respectively;

the second step is that: ethylene-1-butene copolymerization comprising performing an ethylene-1-butene gas phase copolymerization in the presence of the propylene homopolymer component and hydrogen to produce an ethylene-1-butene copolymer component, resulting in a polypropylene material comprising the propylene homopolymer component and an ethylene-1-butene copolymer (ethylene/1-butene copolymer) component.

In the method provided by the invention, the propylene homopolymer component is prepared as a continuous phase to provide certain rigidity for the polypropylene material, and then the ethylene-1-butene copolymer component is prepared as a rubber phase, namely a dispersed phase on the basis of the propylene homopolymer component, so that the toughness of the polypropylene product can be improved.

In the first stage, the amount of hydrogen used may be, for example, from 0 to 200 ppm. In the second stage, the amount of hydrogen used was 2000-.

The process provided by the present invention is preferably carried out in two or more reactors operated in series.

The process according to the invention is a Ziegler-Natta catalyst direct catalysed polymerisation process. Two or more different types of external electron donors are respectively used in a plurality of reactors connected in series, a proper amount of external electron donor is selected, and different amounts of chain transfer agent hydrogen in the reaction are combined to prepare the homo-polypropylene continuous phase with a specific melt index and a large amount of ultrahigh molecular weight components and extremely wide molecular weight distribution. Preferably the molecular weight distribution M of the homopolymeric component_w/M_n(weight average molecular weight/number average molecular weight) 6 to 20, the content of fractions having a molecular weight of more than 500 ten thousand being greater than or equal to 1.5% by weight and less than or equal to 5% by weight; the content of fractions having a molecular weight of less than 5 ten thousand is not less than 15.0 wt.% and not more thanOr equal to 40 wt%; m_z+1/M_n(Z +1 average molecular weight/number average molecular weight) is greater than or equal to 70 and less than 150. And further carrying out copolymerization of ethylene and 1-butene on the basis to obtain a rubber phase dispersed in the continuous phase, and controlling the composition, structure, content and the like of the rubber phase by controlling the reaction conditions of copolymerization reaction to obtain the impact-resistant polypropylene material with high melt strength effect.

In the process provided by the present invention, the catalyst used is a Ziegler-Natta catalyst, preferably a catalyst with high stereoselectivity. The Ziegler-Natta catalyst having high stereoselectivity as used herein means a catalyst which can be used for the preparation of a propylene homopolymer having an isotactic index of more than 95%. Such catalysts generally comprise (1) a titanium-containing solid catalyst active component, the main components of which are magnesium, titanium, halogen and an internal electron donor; (2) an organoaluminum compound co-catalyst component; (3) an external electron donor component.

The solid catalyst active component (which may also be referred to as a procatalyst) of the Ziegler-Natta catalyst used in the process of the present invention may be well known in the art. Specific examples of such active solid catalyst component (1) containing that can be used are, for example, described in patent documents CN85100997, CN98126383.6, CN98111780.5, CN98126385.2, CN93102795.0, CN00109216.2, CN99125566.6, CN99125567.4 and CN 02100900.7. These patent documents are incorporated by reference herein in their entirety.

The organoaluminum compound in the Ziegler-Natta catalyst used in the process of the present invention is preferably an alkylaluminum compound, more preferably a trialkylaluminum, for example, at least one of triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, trihexylaluminum and the like.

The molar ratio of the titanium-containing active solid catalyst component and the organoaluminum compound in the Ziegler-Natta catalyst used in the process of the present invention is 10:1 to 500:1, preferably 25:1 to 100:1, in terms of aluminum/titanium.

According to the invention, said first external electron donor is preferably selected from those of formula R¹R²Si(OR³)₂At least one of the compounds of (a); wherein R is²And R¹Each independently selected from C₁-C₆Straight or branched alkyl, C₃-C₈Cycloalkyl and C₅-C₁₂Heteroaryl of (A), R³Is C₁-C₃A straight chain aliphatic group. Specific examples include, but are not limited to, methyl-cyclopentyl-dimethoxysilane, ethyl-cyclopentyl-dimethoxysilane, n-propyl-cyclopentyl-dimethoxysilane, bis (2-methylbutyl) -dimethoxysilane, bis (3-methylbutyl) -dimethoxysilane, 2-methylbutyl-3-methylbutyl-dimethoxysilane, bis (2, 2-dimethyl-propyl) -dimethoxysilane, 2-methylbutyl-2, 2-dimethyl-propyl-dimethoxysilane, 3-methylbutyl-2, 2-dimethyl-propyl-dimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diisobutyldimethoxysilane, di-tert-dimethoxysilane, di-tert-butyl-dimethoxysilane, di-tert-butyldimethoxysilane, methylcyclohexyldimethoxysilane, methylisobutyldimethoxysilane, dicyclohexyldimethoxysilane, methyl-isopropyldimethoxysilane, isopropyl-cyclopentyldimethoxysilane, dicyclopentyldimethoxysilane, isopropyl-isobutyldimethoxysilane, diisopropyldimethoxysilane and the like.

The molar ratio of the organic aluminum compound to the first external electron donor is 1:1 to 100:1, preferably 10:1 to 60:1, calculated as aluminum/silicon.

In the process according to the invention, the catalyst comprising the first external electron donor may be added directly to the homopolymerization reactor or, after precontacting and/or prepolymerization as known in the art, may be added to the homopolymerization reactor. The prepolymerization refers to that the catalyst is prepolymerized at a certain ratio at a lower temperature to obtain the ideal particle shape and dynamic behavior control. The prepolymerization can be liquid phase bulk continuous prepolymerization, and can also be batch prepolymerization in the presence of an inert solvent. The temperature of the prepolymerization is usually-10 to 50 ℃ and preferably 5 to 30 ℃. A precontacting step may optionally be provided before the prepolymerization process. The pre-contact step refers to the complex reaction of a cocatalyst, an external electron donor and a main catalyst (solid active center component) in the catalyst system to obtain the catalyst system with polymerization activity. The temperature in the precontacting step is usually controlled to be-10 to 50 ℃, preferably 5 to 30 ℃.

According to the invention, the second external electron donor is selected from at least one of the compounds shown in the chemical general formulas (I), (II) and (III);

wherein R is₁And R₂Each independently selected from C₁-C₂₀One of linear, branched or cyclic aliphatic radicals, R₃、R₄、R₅、R₆、R₇And R₈Each independently selected from a hydrogen atom, a halogen atom, C₁-C₂₀Straight or branched alkyl of (2), C₃-C₂₀Cycloalkyl radical, C₆-C₂₀Aryl radical, C₇-C₂₀Alkylaryl and C₇-C₂₀One of aralkyl groups; r₉、R₁₀And R₁₁Each independently is C₁-C₃Straight-chain aliphatic radical, R₁₂Is C₁-C₆Straight or branched alkyl or C₃-C₈A cycloalkyl group. Specific examples of the second external electron donor include, but are not limited to, 2-diisobutyl-1, 3-dimethoxypropane, 2-phenyl-1, 3-dimethoxypropane, 2-benzyl-1, 3-dimethoxypropane, 2-isopropyl-2-isoamyl-1, 3-dimethoxypropane, 2-bis (cyclohexylmethyl) -1, 3-dimethoxypropane, 2-isopropyl-2-3, 7-dimethyloctyl-dimethoxypropane, 2-isopropyl-1, 3-dimethoxypropane, 2-isopropyl-2-cyclohexylmethyl-1, 3-dimethoxypropane, 2-diisobutyl-1, 3-diethoxypropane, 2-diisobutyl-1, 3-dipropoxypropane, 2-isopropyl-2-isoamyl-1, 3-diethoxypropane, 2-isopropyl-2-isoamyl-1, 3-dipropoxypropane, 2-bis (cyclohexylmethyl) -1, 3-diethoxypropane, n-propyltriethoxysilane, isopropyl triethoxy-propane and isopropyl triethoxy-propaneAlkoxysilane, isobutyltriethoxysilane, isobutyltrimethoxysilane, isobutyltripropoxysilane, isobutyltributoxysilane, tert-butyltriethoxysilane, tert-butyltripropoxysilane, tert-butyltributoxysilane, cyclohexyltriethoxysilane, cyclohexyltripropoxysilane, tetraethoxysilane, tetramethoxysilane, tetrapropoxysilane, tetrabutoxysilane, and the like.

The molar ratio of the organic aluminum compound to the second external electron donor is 1:1 to 60:1 in terms of aluminum/silicon or aluminum/oxygen, and preferably 5:1 to 30: 1.

According to some embodiments of the present invention, the molar ratio of the second external electron donor to the first external electron donor is from 1 to 30, preferably from 5 to 30.

In the process of the present invention, it is preferred that the second external electron donor is brought into intimate contact with the catalyst component in the first stage reaction product prior to the second stage homopolymerization. In some preferred embodiments, the second external electron donor may be added in the feed line after the first stage reactor and before the second stage reactor, or at the front end of the feed line of the second stage reactor, in order to first perform a precontacting reaction with the catalyst in the reaction product of the first stage before the second stage reaction.

For high melt strength impact polypropylene, the factors affecting melt strength become more complex due to the material being of multi-phase structure. According to the process of the present invention, it is preferred that the ratio of the melt index of the propylene homopolymer obtained in the first step to the melt index of the polypropylene material comprising the propylene homopolymer component and the ethylene-1-butene copolymer component obtained in the second step is greater than or equal to 0.6 and less than or equal to 1. It is also preferred that the weight ratio of the first propylene homopolymer to the second propylene homopolymer is from 40:60 to 60: 40. Further preferably, the weight ratio of the ethylene-1-butene copolymer component to the propylene homopolymer component is 11-80: 100. By arranging the propylene homopolymer component of the impact polypropylene material of the present invention to comprise a combination of at least two propylene homopolymers having different melt indices and having a specific ratio relationship, the polypropylene material comprising the present invention has a specific dispersed phase, which upon further combination with a rubber phase, results in an impact polypropylene material having both high melt strength and good stiffness and toughness.

According to the present invention, it is preferred that the propylene homopolymer component has the following characteristics: a melt index, measured at 230 ℃ under a load of 2.16kg, of 0.1 to 15g/10min, preferably 0.1 to 6g/10 min; molecular weight distribution M_w/M_n6-20; the fraction having a molecular weight of more than 500 ten thousand is present in an amount of more than or equal to 1.5% by weight and less than or equal to 5% by weight; the content of fractions having a molecular weight of less than 5 ten thousand is greater than or equal to 15.0% by weight and less than or equal to 40% by weight; m_z+1/M_nGreater than or equal to 70 and less than 150.

In the second step, the 1-butene is preferably used in a ratio of 1-butene to the total volume of 1-butene and ethylene of 0.2 to 0.8. Preferably, in the second step, the volume ratio of hydrogen to the total amount of 1-butene and ethylene is between 0.02 and 1. Meanwhile, as described above, in the first stage, the amount of hydrogen used may be, for example, 0 to 200 ppm. In the second stage, the amount of hydrogen used may be 2000-20000 ppm. In the present invention, control of the composition, structure or properties of the dispersed and continuous phases is important in order to obtain an impact-resistant polypropylene material having high melt strength, as well as high stiffness and toughness. The present invention, through these preferred conditions, can prepare a rubber phase having a molecular weight distribution, ethylene content, which is advantageous for achieving the objects of the present invention, thereby obtaining an impact polypropylene material having better properties.

In a preferred embodiment of the present invention, the yields of the first propylene homopolymer and the second propylene homopolymer are in the range of from 40:60 to 60: 40. The yield ratio of the ethylene-1-butene copolymer component to the propylene homopolymer component is 11-80: 100.

The polymerization reaction of the first step may be carried out in liquid-liquid phase, or in gas-gas phase, or using a combination of liquid-gas techniques. When liquid phase polymerization is carried out, the polymerization temperature is 0-150 ℃, preferably 60-100 ℃; the polymerization pressure should be higher than the saturation vapor pressure of propylene at the corresponding polymerization temperature. The polymerization temperature in the gas phase polymerization is 0 to 150 ℃, preferably 60 to 100 ℃; the polymerization pressure may be normal pressure or higher, and preferably 1.0 to 3.0MPa (gauge pressure, the same applies hereinafter).

The polymerization reaction of the second step is carried out in the gas phase. The gas phase reactor may be a gas phase fluidized bed, a gas phase moving bed, or a gas phase stirred bed reactor. The polymerization temperature is preferably 0 to 150 ℃ and more preferably 60 to 100 ℃. The polymerization pressure is any pressure below the partial pressure of the propylene at which it liquefies.

According to a preferred embodiment of the invention, the reaction temperature in the first stage is between 50 and 100 ℃, preferably between 60 and 85 ℃; the reaction temperature of the second stage is 55-100 ℃, preferably 60-85 ℃; the reaction temperature in the second step is 55-100 deg.C, preferably 60-85 deg.C.

According to the process of the present invention, the polymerization reaction may be carried out continuously or batchwise.

M of the Room temperature trichlorobenzene solubles of the Polypropylene Material obtained in the second step according to the Process of the present invention_wM with trichlorobenzene insolubles at room temperature_wA ratio of greater than 0.5 and less than 1, preferably greater than 0.5 and less than 0.8; the ethylene-1-butene copolymer has a butene content of 20% by weight or more and 45% by weight or less. The rigidity and toughness of the polypropylene material obtained in the way are further optimized, and meanwhile, higher melt strength is guaranteed. In the present invention, the room temperature xylene solubles content is determined according to the method described in astm d 5492. Here, it is easily understood that the "butene content in the ethylene-1-butene copolymer" means the weight content of the butene monomer constituting part of the ethylene-1-butene copolymer copolymerized from the ethylene monomer and the 1-butene monomer.

According to the process of the invention, the polypropylene material obtained in the second step has a melt index, measured at 230 ℃ under a load of 2.16kg, of between 0.1 and 15g/10min, preferably between 0.1 and 6g/10 min; molecular weight distribution M of the material_w/M_nLess than or equal to 10 and greater than or equal to4；M_z+1/M_wGreater than 10 and less than 20.

In a preferred embodiment of the present invention, the method of the present invention further comprises further modifying the prepared impact polypropylene material with an alpha or beta crystal nucleating agent to further improve the rigidity or toughness of the polypropylene resin material. Suitable alpha crystal and beta crystal nucleating agent modification is well known in the art. The ratio of the weight of the nucleating agent to the total weight of the polypropylene is usually (0.005-3): 100.

The invention also provides a high melt strength impact polypropylene material prepared according to the process described above, comprising a propylene homopolymer component and an ethylene-1-butene copolymer component, wherein the propylene homopolymer component comprises at least a first propylene homopolymer and a second propylene homopolymer; the weight ratio of the ethylene-1-butene copolymer component to the propylene homopolymer component is 11-80:100, and the butene content in the ethylene-1-butene copolymer is greater than or equal to 20 wt% and less than or equal to 45 wt%.

The invention adopts the ethylene-1-butene-random copolymer as the rubber component, and the inventor of the invention finds that the effect is better when the weight ratio of the ethylene-1-butene copolymer component to the propylene homopolymer component is 11-80:100 in the impact-resistant polypropylene material of the invention through a large amount of experiments; further, when the butene content in the ethylene-1-butene copolymer is made to be greater than or equal to 20% by weight and less than or equal to 45% by weight, an impact polypropylene material having better rigidity and toughness is obtained. The polypropylene product of the invention has better rigidity-toughness balance.

The room temperature xylene solubles content of the impact polypropylene material according to the invention is preferably more than 10 wt% and less than 30 wt%; m of room temperature trichlorobenzene soluble substance_wM with trichlorobenzene insolubles at room temperature_wThe ratio of (d) is preferably greater than 0.5 and less than 1, preferably greater than 0.5 and less than 0.8. The rigidity and toughness of the polypropylene material are further optimized, and the polypropylene material has higher melt strength.

Impact resistant polymers of the inventionThe melt index of the propylene material is preferably controlled in the range of 0.1 to 15g/10min, preferably 0.1 to 10g/10min, and further preferably 0.1 to 6.0g/10 min. The melt index was measured at 230 ℃ under a load of 2.16 kg. For high melt strength impact polypropylene, the factors affecting melt strength become more complex due to the material being of multi-phase structure. The inventors have found that the molecular weight distribution M of the impact polypropylene material is such that, in order to ensure a high melt strength of the product, the impact polypropylene material has a molecular weight distribution M_w/M_nPreferably less than or equal to 10 and greater than or equal to 4, M_z+1/M_wGreater than 10 and less than 20, preferably greater than 10 and less than 15.

In some preferred embodiments, the impact polypropylene material of the present invention has a butene content of from 5 to 20 weight percent.

The impact polypropylene material according to the present invention has a molecular weight Polydispersity Index (PI) of from 4 to 8, preferably from 4.5 to 6.

According to the present invention there is provided an impact polypropylene material prepared by performing a propylene homopolymerization reaction in the presence of a first propylene homopolymer to obtain a propylene homopolymer component comprising the first propylene homopolymer and a second propylene homopolymer, and then performing an ethylene-1-butene copolymerization reaction in the presence of the propylene homopolymer component to obtain a material comprising an ethylene-1-butene copolymer. It follows that the impact polypropylene material of the present invention is not a simple blend of a propylene homopolymer component and an ethylene-1-butene copolymer component, but is instead a unitary polypropylene material comprising a propylene homopolymer and an ethylene-1-butene copolymer obtained after further specific ethylene-1-butene copolymerization on the basis of a specific propylene homopolymer component.

The polypropylene material also has good heat resistance, and the melting peak temperature T of the final polypropylene resin is measured by DSC_mGreater than or equal to 158 ℃.

In the preparation method of the impact-resistant polypropylene material, the added second external electron donor can react with the catalytic activity center in the homopolymerization product material in the first stage to generate a new catalytic activity center, and propylene is continuously initiated to polymerize into a homopolymerization polymer with a molecular weight which is greatly different from that of the product obtained in the first stage in the second stage. The second external electron donor has higher hydrogen response than the first external electron donor, and can prepare a high melt index polymer in the presence of a small amount of hydrogen. Therefore, the invention can obtain the homopolymerized polypropylene component containing a large amount of ultrahigh molecular weight fraction and wider molecular weight distribution under the condition of less hydrogen consumption by adjusting the dosage and the type of the external electron donor and the adding amount of the hydrogen at different stages when the homopolymerized polypropylene component is added into two reactors connected in series or is intermittently operated without using a special catalyst. Then, proper 1-butene/(1-butene + ethylene), hydrogen/(1-butene + ethylene) and temperature and pressure are selected to further carry out ethylene-1-butene copolymerization reaction on the basis of the homopolymerized polypropylene component, so as to obtain the high melt strength impact resistant polypropylene containing a certain content of rubber component with specific performance. The composition and structure control of the rubber phase component ensures that the rubber phase component has high melt strength, the specific content of the rubber component ensures that the rubber phase component has higher impact resistance, and in addition, the proper molecular weight distribution also ensures that the polymer has good processability. That is, the present invention obtains a polypropylene material having excellent properties on the basis of setting a plurality of propylene homopolymerization stages and selecting appropriate individual reaction parameters and reaction conditions for the individual homopolymerization and copolymerization reactions to produce appropriate continuous and rubber dispersed phases and a combination relationship thereof.

The impact-resistant polypropylene material provided by the invention has the characteristics of high melt strength, high rigidity and high toughness, so that the impact-resistant polypropylene material is an excellent material suitable for the fields of automobile parts, medical instruments, household articles and the like. The preparation method of the high-melt-strength impact-resistant polypropylene material provided by the invention is simple and effective and is easy to operate.

Detailed Description

The invention will now be further described by way of specific examples, which are not to be construed as limiting the invention in any way.

The polymer related data in the examples were obtained according to the following test methods:

the xylene soluble content (namely the content of a characteristic rubber phase) of the polymer at room temperature is measured according to the method of ASTM D5492;

measuring the tensile strength of the resin according to a GB/T1040.2 method;

③ melt mass flow rate (also known as melt index, MFR): measured according to ASTM D1238 with a melt index meter model 7026 from CEAST, at 230 ℃ under a load of 2.16 kg;

bending modulus: measured according to the method described in GB/T9341;

impact strength of the simply supported beam notch: measured according to the method described in GB/T1043.1;

sixthly, the ethylene content and the butylene content are as follows: measured by a nuclear magnetic resonance method. The measurement was carried out using a 10 mm probe of AVANCEIII400MHz nuclear magnetic resonance spectrometer (NMR) from Bruker, Switzerland. The solvent is deuterated o-dichlorobenzene, about 250mg of the sample is placed in 2.5ml of deuterated solvent, and the sample is dissolved by heating in an oil bath at 140 ℃ to form a uniform solution. And (3) acquiring 13C-NMR (nuclear magnetic resonance), wherein the probe temperature is 125 ℃, 90-degree pulses are adopted, the sampling time AQ is 5 seconds, the delay time D1 is 10 seconds, and the scanning times are more than 5000 times. Other manipulations, peak identification, etc. commonly used NMR experimental requirements are performed, and references include EricT. Hsieh, and James C. randall, Ethylene-1-ButeneCoopomers.1. Comonomer sequence distribution, Macromolecules,15, 353-.

Melt strength: the melt strength was measured using a Rheotens melt Strength Meter manufactured by Geottfert WerkstoffPruefMaschinen, Germany. After the polymer is melted and plasticized by a single screw extruder, a melt bar is extruded downwards by a 90-degree steering head provided with an 30/2 length-diameter-ratio die, the bar is clamped between a group of two rollers which rotate oppositely at constant acceleration to carry out uniaxial stretching, the force in the melt stretching process is measured and recorded by a force measuring unit connected with the stretching rollers, and the maximum force value measured when the melt is stretched until the melt is broken is defined as the melt strength.

⑧ molecular weight Polydispersity Index (PI) resin samples were molded into 2mm sheets at 200 deg.C, subjected to dynamic frequency scanning at 190 deg.C under nitrogen using an ARES (advanced rheometer extension system) rheometer from Rheometric scientific Inc, parallel plate clamps were selected, appropriate strain amplitude was determined to ensure that the experiment was performed in the linear region, and the change in storage modulus (G '), dissipation modulus (G') and the like with frequency was measured for the samples, the molecular weight polydispersity index PI was 10⁵/G_cWherein G is_c(unit: Pa) is the modulus value at the intersection of the G '-frequency curve and the G' -frequency curve.

⑨ molecular weight (M)_w、M_n) And molecular weight distribution (Mw/Mn, Mz + 1/Mw): the molecular weight and molecular weight distribution of the sample were measured by PL-GPC220 gel permeation chromatograph manufactured by Polymer laboratories, UK, or GPCIR apparatus manufactured by Polymer char, Spain (IR5 concentration detector), the chromatographic column was 3 PLgel13umOlexis columns in series, the solvent and mobile phase was 1,2, 4-trichlorobenzene (containing 250ppm of antioxidant 2, 6-dibutyl-p-cresol), the column temperature was 150 ℃, the flow rate was 1.0ml/min, and the calibration was carried out universally by EasiCalPS-1 narrow distribution polystyrene standard manufactured by PL. The preparation process of the room temperature trichlorobenzene soluble substance comprises the following steps: accurately weighing a sample and a trichlorobenzene solvent, dissolving for 5 hours at 150 ℃, standing for 15 hours at 25 ℃, and filtering by adopting quantitative glass fiber filter paper to obtain a solution of trichlorobenzene soluble matters at room temperature for determination. The content of trichlorobenzene solubles at room temperature was determined by correcting the GPC curve area with polypropylene of known concentration, and the molecular weight data of trichlorobenzene insolubles at room temperature was calculated from the GPC data of the original sample and the GPC data of trichlorobenzene solubles at room temperature.

Example 1

The propylene polymerization reaction is carried out on a polypropylene device, and the main equipment of the device comprises a prepolymerization reactor, a first loop reactor, a second loop reactor and a third gas-phase reactor. The polymerization method and the steps are as follows.

(1) Prepolymerization reaction

The main catalyst (DQC-401 catalyst, supplied by Oda, Beijing of China petrochemical catalyst Co.), the cocatalyst (triethylaluminum) and the first external electron donor (isopropyl cyclopentyl dimethoxysilane, IPCPMS) were precontacted at 6 ℃ for 20min, and then continuously added into a continuous stirred tank type prepolymerization reactor to perform a prepolymerization reactor. The Triethylaluminum (TEA) flow into the prepolymerization reactor was 6.33g/hr, the isopropylcyclopentyldimethoxysilane flow was 0.3g/hr, the procatalyst flow was 0.6g/hr, and the TEA/IPCPMS ratio was 50 (mol/mol). The prepolymerization is carried out in a propylene liquid phase bulk environment, the temperature is 15 ℃, the residence time is about 4min, and the prepolymerization multiple of the catalyst is about 80-120 times under the condition.

(2) The first step is as follows: homopolymerization of propylene

The first stage is as follows: continuously feeding the prepolymerized catalyst into a first loop reactor to complete the first-stage propylene homopolymerization, wherein the polymerization temperature of the first loop reactor is 70 ℃, and the reaction pressure is 4.0 MPa; and (3) adding no hydrogen into the feed of the first loop reactor, wherein the concentration of the hydrogen detected by an online chromatographic method is less than 10ppm, so as to obtain a first propylene homopolymer A.

And a second stage: isobutyl triethoxysilane (IBTES) was added at 0.63g/hr with propylene in the second loop reactor and mixed with the reactant stream from the first loop reactor with a TEA/IBTES ratio of 5(mol/mol), where IBTES is the second external electron donor. The polymerization temperature of the second loop reactor is 70 ℃, and the reaction pressure is 4.0 MPa; a quantity of hydrogen was also added with the propylene feed, the hydrogen concentration in the feed was 3300ppm by on-line chromatographic detection, and a second propylene homopolymer B was produced in the second loop reactor, yielding a propylene homopolymer fraction comprising a first propylene homopolymer and a second propylene homopolymer.

(3) The second step is that: copolymerization of ethylene and butadiene

A certain amount of hydrogen and H is added into the third reactor₂/(C₂+C₄)＝0.06(v/v)，C₄/(C₂+C₄)＝0.45(v/v)(C₂And C₄Respectively referring to ethylene and 1-butene), the reaction temperature was 75 ℃, and the ethylene/1-butene copolymerization was continuously initiated in the third reactor to produce the ethylene-1-butene copolymer component C.

The final product contains the first propylene homopolymer, the second propylene homopolymer and the ethylene-1-butene copolymer, and is subjected to wet nitrogen to remove the activity of the unreacted catalyst and heating and drying to obtain polymer powder. The powder obtained by polymerization was added with 0.1 wt% of IRGAFOS168 additive, 0.1 wt% of IRGANOX1010 additive and 0.05 wt% of calcium stearate, and pelletized with a twin-screw extruder. The analysis results of the obtained polymer and the physical properties of the polymer are shown in tables 1 and 2.

Example 2

Example 2 the catalyst, pre-complexation, polymerization process conditions and formulation of the auxiliaries and amounts added were the same as in example 1. The difference from the embodiment 1 is that: the amount of hydrogen in the second reactor in the second stage became 7000ppm, and H in the gas phase reactor in the second stage₂/(C₂+C₄) Adjusted to 0.20 (v/v). The analysis results of the obtained polymer and the physical properties of the polymer are shown in tables 1 and 2.

Example 3

Example 3 the catalyst, pre-complexation, polymerization process conditions and formulation of the auxiliaries and amounts added were the same as in example 1. The difference from the embodiment 1 is that: the amount of hydrogen in the second reactor in the second stage became 10000ppm, and the amount of H in the gas phase reactor in the second stage₂/(C₂+C₄) Adjusted to 0.51 (v/v). The analysis results of the obtained polymer and the physical properties of the polymer are shown in tables 1 and 2.

Example 4

Example 4 the catalyst, pre-complexation, polymerization process conditions and formulation of the auxiliaries and amounts added were the same as in example 1. The difference from the embodiment 1 is that: the second external electron donor was changed to 2, -isopropyl-2-isoamyl-1, 3-dimethoxypropane (IPPMP), the amount of the added was unchanged, and the amount of hydrogen in the second reactor was adjusted to 4000ppm in the second stage. The analysis results of the obtained polymer and the physical properties of the polymer are shown in tables 1 and 2.

Example 5

Example 5 the catalyst, pre-complexation, polymerization process conditions and formulation of the auxiliaries and amounts added were the same as in example 3. The difference from the embodiment 3 is that: the first external electron donor was replaced with isopropyl-2-isobutyl-dimethoxysilane (IPBMS), and the amount added was unchanged. The analysis results of the obtained polymer and the physical properties of the polymer are shown in tables 1 and 2.

Example 6

Example 6 the catalyst, pre-complexation, polymerization process conditions and formulation of the auxiliaries and amounts added were the same as in example 1. The difference from the embodiment 1 is that: the amount of hydrogen in the second reactor in the second stage was changed to 6000ppm, and the amount of H in the gas phase reactor in the second stage₂/(C₂+C₄) Adjusted to 0.15(v/v), C₄/(C₂+C₄) Adjusted to 0.25 (v/v). The analysis results of the obtained polymer and the physical properties of the polymer are shown in tables 1 and 2.

From the results shown in tables 1 and 2, it can be seen that the polypropylene material prepared according to the method of the present invention has high melt strength, and simultaneously has high tensile strength, flexural modulus, and notched impact strength. Therefore, the method provided by the invention can be used for preparing the impact-resistant polypropylene material with high melt strength, high rigidity and high toughness. The polypropylene material with excellent performance has wide application value.

Although the present invention has been described in detail, modifications within the spirit and scope of the invention will be apparent to those skilled in the art. Moreover, it should be understood that the various aspects recited, portions of different embodiments (aspects), and various features recited may be combined or interchanged either in whole or in part. In the various embodiments described above, those embodiments that refer to another embodiment may be combined with other embodiments as appropriate, as will be appreciated by those skilled in the art. Furthermore, those skilled in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention.

Claims

1. A method for preparing a high melt strength impact polypropylene material, comprising:

the first step is as follows: propylene homopolymerization comprising:

and a second stage: adding a second external electron donor to perform a complex reaction with a catalyst in the reactant flow, and then performing a propylene homopolymerization reaction in the presence of the first propylene homopolymer and hydrogen to generate a second propylene homopolymer, so as to obtain a propylene homopolymer component containing the first propylene homopolymer and the second propylene homopolymer;

wherein,

the second step is that: ethylene-1-butene copolymerization comprising gas phase copolymerization of ethylene and 1-butene in the presence of the propylene homopolymer component and hydrogen to produce an ethylene-1-butene copolymer component, resulting in a polypropylene material comprising the propylene homopolymer component and the ethylene-1-butene copolymer component.

2. The method of claim 1, wherein the first external electron donor is selected from the group consisting of those of the formula R¹R²Si(OR³)₂At least one of the compounds of (a); wherein R is²And R¹Each independently selected from C₁-C₆Straight or branched alkyl, C₃-C₈Cycloalkyl and C₅-C₁₂Heteroaryl of (A), R³Is C₁-C₃A straight chain aliphatic group.

3. The method according to claim 1 or 2, wherein the second external electron donor is selected from at least one of the compounds represented by the general chemical formulas (I), (II) and (III);

wherein R is₁And R₂Each independently selected from C₁-C₂₀One of linear, branched or cyclic aliphatic radicals, R₃、R₄、R₅、R₆、R₇And R₈Each independently selected from a hydrogen atom, a halogen atom, C₁-C₂₀Of a straight chain orBranched alkyl radical, C₃-C₂₀Cycloalkyl radical, C₆-C₂₀Aryl radical, C₇-C₂₀Alkylaryl and C₇-C₂₀One of aralkyl groups; r₉、R₁₀And R₁₁Each independently is C₁-C₃Straight-chain aliphatic radical, R₁₂Is C₁-C₆Straight or branched alkyl or C₃-C₈A cycloalkyl group.

4. The process according to any one of claims 1 to 3, wherein the molar ratio of the second external electron donor to the first external electron donor is from 5 to 30.

5. The process according to any one of claims 1 to 4, characterized in that the first external electron donor is selected from the group consisting of methyl-cyclopentyl-dimethoxysilane, ethyl-cyclopentyl-dimethoxysilane, n-propyl-cyclopentyl-dimethoxysilane, bis (2-methylbutyl) -dimethoxysilane, bis (3-methylbutyl) -dimethoxysilane, 2-methylbutyl-3-methylbutyl-dimethoxysilane, bis (2, 2-dimethyl-propyl) -dimethoxysilane, 2-methylbutyl-2, 2-dimethyl-propyl-dimethoxysilane, 3-methyl-2, 2-dimethyl-propyl-dimethoxysilane, di (3-methylbutyl-dimethoxysilane, di (2-methyl-propyl) -dimethoxysilane, di (2-methyl, At least one of dimethyldimethoxysilane, dimethyldiethoxysilane, diisobutyldimethoxysilane, methylcyclohexyldimethoxysilane, methylisobutyldimethoxysilane, dicyclohexyldimethoxysilane, methyl-isopropyldimethoxysilane, isopropyl-cyclopentyldimethoxysilane, dicyclopentyldimethoxysilane, isopropyl-isobutyldimethoxysilane, and diisopropyldimethoxysilane;

the second external electron donor is selected from 2, 2-diisobutyl-1, 3-dimethoxypropane, 2-phenyl-1, 3-dimethoxypropane, 2-benzyl-1, 3-dimethoxypropane, 2-isopropyl-2-isoamyl-1, 3-dimethoxypropane, 2-bis (cyclohexylmethyl) -1, 3-dimethoxypropane, 2-isopropyl-2-3, 7-dimethyloctyl-dimethoxypropane, 2-isopropyl-1, 3-dimethoxypropane, 2-isopropyl-2-cyclohexylmethyl-1, 3-dimethoxypropane, 2-diisobutyl-1, 3-diethoxypropane, 2, 2-diisobutyl-1, 3-dipropoxypropane, 2-isopropyl-2-isoamyl-1, 3-diethoxypropane, 2-isopropyl-2-isoamyl-1, 3-dipropoxypropane, 2-bis (cyclohexylmethyl) -1, 3-diethoxypropane, n-propyltriethoxysilane, i-butyltriethoxysilane, i-butyltrimethoxysilane, i-butyltripropoxysilane, at least one of isobutyl tributoxysilane, tert-butyl triethoxysilane, tert-butyl tripropoxysilane, tert-butyl tributoxysilane, cyclohexyl triethoxysilane, cyclohexyl tripropoxysilane, tetraethoxysilane, tetramethoxysilane, tetrapropoxysilane, and tetrabutoxysilane.

6. The process according to any one of claims 1 to 5, wherein the ratio of the melt index of the propylene homopolymer component obtained in the first step to the melt index of the polypropylene material comprising the propylene homopolymer component and the ethylene-1-butene copolymer component obtained in the second step is greater than or equal to 0.6 and less than or equal to 1.

7. The process according to any one of claims 1 to 6, characterized in that the weight ratio of the first propylene homopolymer and the second propylene homopolymer is from 40:60 to 60: 40; the weight ratio of the ethylene-1-butene copolymer component to the propylene homopolymer component is 11-80: 100.

8. The process according to any of claims 1 to 7, characterized in that the propylene homopolymer component has the following characteristics:

a melt index, measured at 230 ℃ under a load of 2.16kg, of 0.1 to 15g/10min, preferably 0.1 to 6g/10 min;

molecular weight distribution M_w/M_n＝6-20；

The fraction having a molecular weight of more than 500 ten thousand is present in an amount of more than or equal to 1.5% by weight and less than or equal to 5% by weight;

the content of fractions having a molecular weight of less than 5 ten thousand is greater than or equal to 15.0% by weight and less than or equal to 40% by weight;

M_z+1/M_ngreater than or equal to 70 and less than 150.

9. Process according to any one of claims 1 to 8, characterized in that the M of the room temperature trichlorobenzene solubles of the polypropylene material obtained in the second step_wM with trichlorobenzene insolubles at room temperature_wThe ratio is greater than 0.5 and less than 1; the ethylene-1-butene copolymer has a butene content of 20% by weight or more and 45% by weight or less.

10. The process according to any one of claims 1 to 9, characterized in that in the second step, the ratio of 1-butene to the total volume of 1-butene and ethylene is from 0.2 to 0.8; the ratio of hydrogen to the total volume of 1-butene and ethylene is 0.02 to 1.

11. The process according to any one of claims 1 to 10, wherein the reaction temperature in the first stage is 50 to 100 ℃, preferably 60 to 85 ℃; the reaction temperature of the second stage is 55-100 ℃, preferably 60-85 ℃; the reaction temperature in the second step is 55-100 deg.C, preferably 60-85 deg.C.