Polypropylene resin, preparation method thereof and polypropylene material

Abstract

The invention discloses polypropylene resin, a preparation method thereof and a polypropylene material, the polypropylene resin is a binary copolymer of propylene and 1-hexene, and the impact strength at-20 DEG C is 3-7 KJ / m < 2 >. The polypropylene resin is prepared by adopting a solution polymerization method, and a titanium-containing Ziegler-Natta catalyst is adopted and comprises a main catalyst, a co-catalyst and an external electron donor; the internal electron donor in the main catalyst comprises a dicarboxylic acid ester compound and a 1, 3-diether compound. The polypropylene resin itself has high low temperature impact strength and low haze. The antioxidant, the deacidification agent and the anti-reflection agent are simultaneously added into the polypropylene resin base material, and the prepared polypropylene material has the characteristics of high low-temperature impact strength, high transparency, low ash content and the like, and meets the preparation of injection molding products in the fields of medical tube materials, medical packaging, food packaging and the like with relatively high requirements on low-temperature impact and transparency.

Description

Technical Field

[0001] The invention relates to the technical field of olefin polymerization, and in particular to a polypropylene resin with excellent low-temperature impact resistance and a preparation method thereof, and a polypropylene material. Background Art

[0002] The application of isotactic polypropylene is severely limited due to its high brittleness and poor transparency. In order to expand the application range of polypropylene, propylene and α-olefin are generally copolymerized to make random copolymer polypropylene to reduce its brittleness and improve its transparency. Existing random copolymer polypropylene products mainly use ethylene and propylene copolymerization, but the low molecular weight substances in ethylene-propylene random copolymer polypropylene are easy to migrate to the surface of the material, affecting the transparency and surface gloss of the material. Therefore, it is necessary to find other olefins to copolymerize with propylene to improve the performance of the product.

[0003] Commonly used α-olefins mainly include ethylene, 1-butene, 1-hexene and 1-octene. With the transformation and upgrading of domestic refining and chemical business, long-chain α-olefins such as 1-hexene and 1-octene will gradually replace 1-butene as comonomers, and the polyolefin products produced will have better performance and higher added value. Compared with propylene / ethylene copolymers, the melt strength, impact strength, transparency and weather resistance of propylene / 1-hexene copolymers can be significantly improved, and the crystals of propylene / 1-hexene copolymers are smaller and the phase structure is more uniform, which is beneficial to impact resistance.

[0004] The preparation process of olefin copolymers includes bulk method, gas phase method, solution method and slurry method. Bulk polymerization is divided into gas phase bulk method and liquid phase bulk method. The gas phase bulk method is to polymerize gaseous monomers into polymers under high temperature and pressure through catalysts, while the liquid phase bulk method is to polymerize liquid monomers into polymers under the action of catalysts. Slurry polymerization is a method of monomer polymerization reaction, which belongs to a type of precipitation polymerization. It refers to the polymerization reaction in which the initiator of the polymerization reaction and the formed polymer are not soluble in the monomer itself and the solvent (diluent); the solvent added in the slurry polymerization mainly plays the role of diluting the monomer concentration and discharging part of the reaction heat. Solution polymerization is that olefin monomers are dissolved in alkane solvents under the action of catalysts, and the polymerization reaction is carried out in the solution. Compared with bulk polymerization and slurry polymerization, the solvent in solution polymerization can be used as a heat transfer medium to make the system heat transfer easier and the temperature easier to control; the system viscosity is lower, the gel effect is reduced, and local overheating can be avoided. At present, the industrial polymerization process of polybutene-1 is mainly based on gas phase method, bulk method and slurry method.

[0005] For example, Chinese patent document CN201480058456.1 discloses that a multimodal copolymer of propylene / 1-hexene is obtained in at least two connected gas phase polymerization reactors using a Ziegler-Natta catalytic system, wherein the content of 1-hexene derived units is 0.6wt%-3.0wt%, which is suitable for the production of industrial panels; the propylene / 1-hexene copolymer obtained by this method has an impact strength of 8KJ / m at 0°C. 2 , and the bending modulus is 1520Mpa. Chinese patent document CN200880122494.3 discloses that a propylene / 1-hexene copolymer is obtained in at least two connected gas phase polymerization reactors using a Ziegler-Natta catalytic system, wherein the copolymer has a xylene soluble portion of less than 5% relative to the total weight of the copolymer, and the propylene / 1-hexene copolymer is particularly suitable for plastic tanks, especially expansion tanks.

[0006] Chinese patent documents CN201680068706.9, CN201880026510.2, and CN201880044856.5 provide a propylene / 1-hexene copolymer having a high haze value and a low sealing initiation temperature for producing a film, preferably a cast film or a BOPP film monolayer or multilayer, wherein at least one layer comprises the composition of the present disclosure. Chinese patent documents CN200880121585.5, CN201980057315.0, and CN201980056582.6 disclose a propylene / hexene-1 copolymer having a good balance of impact resistance (such as dart impact strength) and tear propagation resistance for producing blown films. Chinese patent document CN201980057350.2 provides a propylene / 1-hexene copolymer for producing a film, more preferably a cast film. Chinese patent document CN201510042369.3 discloses a copolymer of propylene and 1-hexene, which contains 5-9wt% of repeating units derived from 1-hexene, has a melting temperature of 125°C-140°C, and a melt flow rate of 0.1-3g / 10min, and is used to produce blown films with valuable mechanical and optical properties.

[0007] Chinese patent document CN201280035049.X discloses a tape of propylene / 1-hexene copolymer, in which the hexene content of the propylene / 1-hexene copolymer is 0.3wt%-5.0wt%; the melt flow rate is 0.3g / 10min-11g / 10min; the melting point is higher than 145°C, preferably between 146°C and -159°C; the tape of the propylene / 1-hexene copolymer has high tensile strength.

[0008] It can be seen that the existing propylene / 1-hexene copolymer mainly adopts the method of gas phase polymerization. According to different application requirements, the mechanics, fluidity, transparency and other aspects are improved to varying degrees by adjusting the monomer hexene content and gas phase polymerization parameters. However, the existing propylene / 1-hexene copolymer polypropylene materials need to be further improved in low temperature impact resistance, especially for polypropylene materials used in injection molding products in the fields of medical tube materials, medical packaging and food packaging. However, the existing methods of adjusting the monomer hexene content and gas phase polymerization parameters are not ideal for further improving the low temperature impact resistance of propylene / 1-hexene copolymer polypropylene materials. There are many factors affecting the performance of polypropylene materials, such as the selection of high copolymerization performance catalysts, the selection of polymerization processes, the regulation of monomer content, etc., and these factors have an impact on a certain performance or comprehensive performance. Therefore, how to select a catalyst with high copolymerization performance to further improve the low temperature impact resistance of propylene / 1-hexene copolymers to meet the needs of injection molding products in the fields of medical tube materials, medical packaging and food packaging is a technical problem that needs to be solved urgently. Summary of the invention

[0009] In view of the problems existing in the above-mentioned prior art and the directions for improvement, the present invention provides a polypropylene resin and a preparation method thereof, which can significantly improve the low-temperature impact resistance of the propylene / 1-hexene copolymer by adopting a specific catalyst system combined with a solution polymerization method to control the hexene copolymerization amount and its distribution, and can meet the application requirements in the fields of medical tube materials, medical packaging and food packaging, injection molding products, etc.; and the method is simple to operate and has good stability, and is suitable for small-scale tests, pilot tests and industrial production.

[0010] To achieve the above object, the present invention provides a polypropylene resin, which is a binary copolymer of propylene and 1-hexene, and has an impact strength of 3-7 KJ / m at -20°C. 2 , haze <30%.

[0011] The present invention also provides a method for preparing the above-mentioned polypropylene resin, which adopts a solution polymerization method and comprises the following steps:

[0012] In a nitrogen atmosphere, 1-hexene monomer, titanium-containing Ziegler-Natta catalyst, solvent, chain transfer regulator and propylene are sequentially added into a polymerization kettle for polymerization, and after the polymerization reaction is completed, degassing and flash evaporation are performed to obtain the polypropylene resin;

[0013] The titanium-containing Ziegler-Natta catalyst comprises a main catalyst, a co-catalyst and an external electron donor; the main catalyst comprises a composite internal electron donor, a halogen-containing magnesium compound and a titanium-containing compound, and the composite internal electron donor comprises a dicarboxylic acid ester compound and a 1,3-diether compound.

[0014] Optionally, in the method for preparing the polypropylene resin provided by the present invention, the dicarboxylic acid ester compound has a structure as shown in Formula I,

[0015]

[0016] Wherein, R1 and R2 are independently selected from C1-C8 unsubstituted or substituted alkylene, C2-C8 straight or branched alkenylene, C5-C8 unsubstituted or substituted cycloalkenylene, C3-C8 unsubstituted or substituted cycloalkylene, or R1 and R2 together form a C5-C9 unsubstituted or substituted cyclic alkylene; preferably, R1 and R2 together form a C5-C9 unsubstituted or substituted cyclic alkylene; more preferably, R1 and R2 together form an unsubstituted or substituted cyclohexanedicarboxylic acid ester, or cyclohexene-dicarboxylic acid ester, such as cis+trans-1,2-cyclohexanedicarboxylic acid ester, cis-1,2-cyclohexanedicarboxylic acid ester, cis+trans-4-methyl-1,2-cyclohexanedicarboxylic acid ester, cis-4-cyclohexene-1,2-dicarboxylic acid ester, 1-cyclohexene-1,2-dicarboxylic acid ester, etc.;

[0017] In the above definitions of R1 and R2, "substituted" means that at least one H in the substituted group is replaced by methyl, ethyl, n-propyl and / or isopropyl;

[0018] R3 and R4 are independently selected from C1-C10 unsubstituted or phenyl-substituted alkyl, unsubstituted or substituted phenyl, or unsubstituted or phenyl-substituted C2-C4 alkenyl; wherein "substituted phenyl" means that at least one H on the phenyl group is substituted by a C1-C4 straight-chain or branched alkyl group, and the C1-C4 straight-chain or branched alkyl group is selected from methyl, ethyl, n-propyl, n-butyl or isobutyl;

[0019] Preferably, R3 and R4 are independently selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, phenyl, methylphenyl, ethylphenyl, n-propylphenyl, n-butylphenyl, isobutylphenyl, benzyl, phenethyl, phenylpropyl, phenylvinyl or phenylpropenyl.

[0020] Optionally, in the method for preparing the polypropylene resin provided by the present invention, the 1,3-diether compound has a structure shown in Formula II,

[0021]

[0022] Among them, R III and R IV Each of the following is independently selected from C1-C4 alkyl groups; such as methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, etc.;

[0023] RI and R II are independently selected from H, C1-C18 unsubstituted or substituted alkyl, C3-C18 cycloalkyl, C6-C18 unsubstituted or halogen-substituted aryl, or R I With R II Together they form a C9-C15 unsubstituted or substituted fused cyclic hydrocarbon, a C7-C12 bridged cyclic hydrocarbon, or a C5-C25 unsubstituted or substituted cycloolefin;

[0024] Preferably, the cycloalkyl group is selected from cyclohexyl or cyclopentyl, the condensed ring hydrocarbon is selected from any one of indene, fluorene, benzonaphthalene, naphthalene, anthracene, dihydronaphthalene and dihydroanthracene, the bridged ring hydrocarbon is selected from norbornadiene; the cycloolefin is selected from cyclohexadiene, cyclopentadiene or cycloheptatriene;

[0025] The above R I and R II In the definition of, "substituted" in "C9-C15 unsubstituted or substituted condensed cyclic hydrocarbon" means that at least one H in the substituted condensed cyclic hydrocarbon is substituted by halogen, C1-C6 branched or straight-chain alkyl (such as methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, etc.), C4-C6 cycloalkyl (such as cyclopentyl, cyclohexyl, etc.), alkoxy (such as methoxy, ethoxy, etc.) and / or phenyl; "substituted" in "C1-C18 unsubstituted or substituted alkyl" means that at least one H on the substituted alkyl is substituted by phenyl, C1-C6 branched or straight-chain alkyl, C3-C6 cycloalkyl (such as cyclohexyl, cyclopentyl, cyclobutyl, etc.) and / or naphthyl; "substituted" in "C5-C25 unsubstituted or substituted cycloolefin" means that at least one H in the substituted cyclic olefin is substituted by methyl, phenyl, halogen and / or cyclopentyl.

[0026] The halogen in the above is selected from F, Cl, Br or I.

[0027] Optionally, in the preparation method of the polypropylene resin provided by the present invention, the 1,3-diether compound can be selected from 2-(2-ethylhexyl)-1,3-dimethoxypropane, 2-isopropyl-1,3-dimethoxypropane, 2-butyl-1,3-dimethoxypropane, 2-sec-butyl-1,3-dimethoxypropane, 2-cyclohexyl-1,3-dimethoxypropane, 2-phenyl-1,3-dimethoxypropane, 2-(2-phenylethyl)-1,3-dimethoxypropane, 2-(2-cyclohexylethyl)-1,3-dimethoxypropane, 2-(p-chlorophenyl)-1,3-dimethoxypropane, 2-(diphenylmethyl)-1,3-dimethoxypropane, 2-(1-naphthyl)-1,3-dimethoxypropane, -(2-fluorophenyl)-1,3-dimethoxypropane, 2,2-dicyclohexyl-1,3-dimethoxypropane, 2,2-dicyclopentyl-1,3-dimethoxypropane, 2,2-diethyl-1,3-dimethoxypropane, 2,2-dipropyl-1,3-dimethoxypropane, 2,2-diisopropyl-1,3-dimethoxypropane, 2,2-dibutyl-1,3-dimethoxypropane, 2-methyl-2-propyl-1,3-dimethoxypropane, 2-methyl-2-benzyl-1,3-dimethoxypropane, 2-methyl-2-ethyl-1,3-dimethoxypropane, 2-methyl-2-isopropyl-1,3-dimethoxypropane, 2-methyl-2-phenyl-1,3-dimethoxypropane, 2-methyl-2-cyclohexyl 2-(2-ethylhexyl)-1,3-dimethoxypropane, 2,2-diisobutyl-1,3-dimethoxypropane, 2,2-diphenyl-1,3-dimethoxypropane, 2,2-dibenzyl-1,3-dimethoxypropane, 2,2-bis(cyclohexylmethyl)-1,3-dimethoxypropane, 2-isobutyl-2-isopropyl-1,3-dimethoxypropane, 2-(1-methylbutyl)-2-isopropyl-1,3-dimethoxypropane, 2-(1-methylbutyl)-2-isopropyl-1,3-dimethoxypropane 3-dimethoxypropane, 2-isopropyl-2-isopentyl-1,3-dimethoxypropane, 2-isopropyl-2-phenyl-1,3-dimethoxypropane, 2-phenyl-2-sec-butyl-1,3-dimethoxypropane, 2-isopropyl-2-benzyl-1,3-dimethoxypropane, 2-isopropyl-2-cyclopentyl-1,3-dimethoxypropane, 2-cyclopentyl-2-sec-butyl-1,3-dimethoxypropane, 2-cyclohexyl-2-isopropyl-1,3-dimethoxypropane, 2-sec-butyl-2-cyclohexyl-1,3-dimethoxypropane, 2-isopropyl-2-sec-butyl-1,3-dimethoxypropane, 2-cyclohexyl-2-cyclohexylmethyl-1,3-dimethoxypropane, 1,1-bis(methoxymethyl)-cyclopentadiene, 1,1-bis(methoxymethyl)-2,3,4,5,-tetramethylcyclopentadiene, 1,1-bis(methoxymethyl)-2,3,4,5,-tetramethylcyclopentadiene, 1,1-bis(methoxymethyl)-2,3,4,5,-tetraphenylcyclopentadiene, 1,1-bis(methoxymethyl)-2,3,4,5,-tetrafluorocyclopentadiene, 1,1-bis(methoxymethyl)-3,4-dicyclopentylcyclopentadiene, 1,1-bis(methoxymethyl)indene, 1,1 -bis(methoxymethyl)-2,3-dimethoxyindene, 1,1-bis(methoxymethyl)-2,3,6,7-tetrafluoroindene, 1,1-bis(methoxymethyl)-4,5,6,7-tetrafluoroindene, 1,1-bis(methoxymethyl)-4,7-dimethylindene, 1,1-bis(methoxymethyl)-3,6-dimethylindene, 1,1-bis(methoxymethyl)-4-phenylindene, 1,1-bis(methoxymethyl)-4-phenyl-2-methylindene, 1,1-bis(methoxymethyl)-4-tetracyclohexylindene, 1,1-bis(methoxymethyl)-7-(3,3,3-trifluoropropyl)phenylindene, 1,1-bis(methoxymethyl)-7-cyclopentylindene, 1,1-bis(methoxymethyl)- 1,1-bis(methoxymethyl)-7-isopropylindene, 1,1-bis(methoxymethyl)-7-cyclohexylindene, 1,1-bis(methoxymethyl)-7-tert-butylindene, 1,1-bis(methoxymethyl)-7-tert-butyl-2-methylindene, 1,1-bis(methoxymethyl)-7-phenylindene, 1,1-bis(methoxymethyl)-2-phenylindene, 9,9-bis(methoxymethyl)fluorene, 9,9-bis(methoxymethyl)-2,7-dicyclopentylfluorene, 9,9-bis(methoxymethyl)-1,8-dichlorofluorene, 9,9-bis(methoxymethyl)-1,8-difluorofluorene, 9,9-bis(methoxymethyl)-1,2,3,4-tetrahydrofluorene, 9,9-bis(methoxymethyl)-4-tert- At least one of butylfluorene, 1,1-bis-(methoxymethyl)-2,5-cyclohexadiene, 1,1-bis-(methoxymethyl)-benzonaphthalene, 7,7-bis-(methoxymethyl)-2,5-norbornadiene, 9,9-bis-(methoxymethyl)-1,4-methanedihydronaphthalene, 9,9-bis-(methoxymethyl)-1,4-methanedihydroanthracene, 4,4-bis-(methoxymethyl)-1-phenyl-1,4-dihydronaphthalene, 4,4-bis-(methoxymethyl)-1-phenyl-3,4-dihydronaphthalene, 5,5-bis-(methoxymethyl)-1,3,6-cycloheptatriene and 1-methoxymethyl-1-(1'-methoxyethyl)-2,3,4,5-tetramethylcyclopentadiene. ,

[0028] Optionally, in the method for preparing the polypropylene resin provided by the present invention, the general formula of the halogen-containing magnesium compound is MgX p R' 2-p , X is halogen, preferably chlorine or bromine; 0<p≤2, R' is selected from C1-C10 straight chain or branched alkyl, C1-C20 straight chain or branched alkoxy, C6-C10 aryl, or C6-C10 aryloxy; preferably, R' is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, n-octyl, phenyl, ethoxy, n-propyloxy, isopropyloxy, n-butyloxy, isobutyloxy, octyloxy or phenoxy.

[0029] Specifically, the halogen-containing magnesium compound is selected from magnesium chloride, magnesium bromide, Grignard reagent, or a halogenating agent or is obtained by reacting with a halogen-free magnesium compound; the halogenating agent is selected from elemental iodine, chlorine, hydrogen chloride, SiCl4 or CCl4, etc.; the Grignard reagent is selected from any one or more of methylmagnesium chloride, ethylmagnesium chloride, ethylmagnesium bromide, ethylmagnesium iodide, n-propylmagnesium chloride, n-propylmagnesium bromide, n-butylmagnesium chloride, n-butylmagnesium bromide, sec-butylmagnesium chloride, sec-butylmagnesium bromide, tert-butylmagnesium chloride, tert-butylmagnesium bromide, hexylmagnesium chloride, octylmagnesium chloride, amylmagnesium chloride, isopentylmagnesium chloride, phenylmagnesium chloride and phenylmagnesium bromide, etc.; The halogen-free magnesium compound can be selected from alkyl magnesium, aryl magnesium, alkoxy magnesium compound or aryloxy magnesium compound, specifically, any one or more of diethyl magnesium, di-n-propyl magnesium, diisopropyl magnesium, di-n-butyl magnesium, di-sec-butyl magnesium, di-tert-butyl magnesium, dipentyl magnesium, n-butylethyl magnesium, n-butyl-sec-butyl magnesium, n-butyloctyl magnesium, diphenyl magnesium, diethoxy magnesium, di-n-propyloxy magnesium, diisopropyloxy magnesium, di-n-butyloxy magnesium, di-sec-butyloxy magnesium, di-tert-butyloxy magnesium, dipentyloxy magnesium, n-butyloxyethoxy magnesium, n-butyloxy-sec-butyloxy magnesium, n-butyloxyoctyloxy magnesium and diphenoxy magnesium.

[0030] Optionally, in the method for preparing the polypropylene resin provided by the present invention, the general formula of the titanium-containing compound is Ti(OR”): n X m , wherein R" is selected from C1-C10 straight or branched alkyl, preferably methyl, ethyl, n-propyl, isopropyl, n-butyl or isobutyl; X is halogen, preferably chlorine or bromine; n is 0, 1, 2, 3 or 4; n+m=3 or 4.

[0031] Specifically, the titanium-containing compound can be selected from any one or more of TiBr3, TiBr4, TiCl3, TiCl4, Ti(OCH3)Cl3, Ti(OC2H5)Cl3, Ti(OC2H5)Br3, Ti(OCH3)2Cl2, Ti(OC2H5)2Cl2, Ti(OC2H5)2Br2, Ti(OCH3)3Cl, Ti(OC2H5)3Cl, Ti(OC2H5)3Br, Ti(OCH3)4 and Ti(OC2H5)4.

[0032] Optionally, in the method for preparing the polypropylene resin provided by the present invention, the following components are included in percentage, based on the mass of the main catalyst being 100%:

[0033]

[0034]

[0035] In the composite internal electron donor, the molar ratio of the dicarboxylic acid ester compound represented by formula I to the 1,3-diether compound represented by formula II is (1-40):(40-1); preferably (1-20):(20-1).

[0036] Optionally, in the preparation method of the polypropylene resin provided by the present invention, the co-catalyst is selected from one or more of alkyl lithium, alkyl magnesium, alkyl zinc, alkyl magnesium halide, alkyl aluminum, alkyl silicon, alkoxide silicon and alkyl silicon halide. Preferably, the co-catalyst is selected from alkyl aluminum and / or alkyl magnesium. More preferably, the co-catalyst is selected from trialkyl aluminum; specifically, the trialkyl aluminum includes any one or more of trimethyl aluminum, triethyl aluminum, triisobutyl aluminum, diethyl aluminum chloride, and C4-C6 cyclic alkyl aluminum.

[0037] Optionally, in the method for preparing the polypropylene resin provided by the present invention, the general formula of the external electron donor is R a L R b H Si(OR c )4-d , where R a , R b R is independently selected from C1-C18 straight or branched alkyl, C5-C7 cycloalkyl or C6-C10 aryl; c Alkyl selected from C1-C4, d=1 or 2, 0≤L≤2, 0≤H≤2, and L+H+(4-d)=4, when d=1, L=0 or H=0.

[0038] Specifically, the external electron donor can be selected from trimethylmethoxysilane, trimethylethoxysilane, trimethylphenoxytriethylmethoxysilane, triethylethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, ethylisopropyldimethoxysilane, propylisopropyldimethoxysilane, diisopropyldimethoxysilane, diisobutyldimethoxysilane, isopropylisobutyldimethoxysilane, di-tert-butyldimethoxysilane, tert-butylmethyldimethoxysilane, tert-butylethyldimethoxysilane, tert-butylpropyldimethoxysilane, tert-butylisopropyldimethoxysilane, tert-butylbutyldimethoxysilane, dimethoxysilane, tert-butylisobutyldimethoxysilane, tert-butyl(sec-butyl)dimethoxysilane, tert-butylpentyldimethoxysilane, tert-butylnonyldimethoxysilane, tert-butylhexyldimethoxysilane, tert-butylheptyldimethoxysilane, tert-butyloctyldimethoxysilane, tert-butyldecyldimethoxysilane, tert-butylmethyldimethoxysilane, cyclohexylmethyldimethoxysilane, cyclohexylethyldimethoxysilane, cyclohexylpropyldimethoxysilane, cyclohexylisobutyldimethoxysilane, dicyclohexyldimethoxysilane, cyclohexyltert-butyldimethoxysilane, cyclopentylmethyldimethoxysilane, cyclopentyl ethyldimethoxysilane, cyclopentylpropyldimethoxysilane, cyclopentyltert-butyldimethoxysilane, dicyclopentyldimethoxysilane, cyclopentylcyclohexyldimethoxysilane, bis(2-methylcyclopentyl)dimethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, phenyltriethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, isopropyltrimethoxysilane, butyltrimethoxysilane, butyltriethoxysilane, isobutyltrimethoxysilane, tert-butyltrimethoxysilane, sec-butyltrimethoxysilane The external electron donor compound may be at least one of dicyclopentyl dimethoxysilane, diisopropyl dimethoxysilane, diisobutyl dimethoxysilane, cyclohexyl trimethoxysilane, diphenyl dimethoxysilane, diphenyl diethoxysilane, phenyl trimethoxysilane, phenyl triethoxysilane, n-propyl trimethoxysilane, vinyl trimethoxysilane, tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, 2-ethylpiperidinyl-2-tert-butyl dimethoxysilane, (1,1,1-trifluoro-2-propyl)-2-ethylpiperidinyl dimethoxysilane and (1,1,1-trifluoro-2-propyl)-methyl dimethoxysilane. More preferably, the external electron donor compound may be at least one of dicyclopentyl dimethoxysilane, diisopropyl dimethoxysilane, diisobutyl dimethoxysilane, cyclohexyl methyl dimethoxysilane, methyl tert-butyl dimethoxysilane and tetramethoxysilane.

[0039] Optionally, in the method for preparing the polypropylene resin provided by the present invention, the mass ratio of propylene to 1-hexene is 2-20:1;

[0040] The chain transfer regulator is hydrogen. Preferably, the molar ratio of the chain transfer regulator to propylene is less than 0.01.

[0041] Optionally, in the method for preparing the polypropylene resin provided by the present invention, the flash evaporation temperature is 150-270° C.;

[0042] The polymerization reaction pressure is 0.1-4.0 MPa, the reaction temperature is 70-150° C., and the reaction time is 0.5-3 h.

[0043] Optionally, in the preparation method of the polypropylene resin provided by the present invention, the solvent is selected from at least one of aliphatic hydrocarbons, alicyclic hydrocarbons and aromatic hydrocarbon solvents that are liquid at room temperature and pressure; preferably, the aliphatic hydrocarbons are selected from C6-C12 straight-chain alkanes or kerosene, and the alicyclic hydrocarbons are selected from cyclopentane, cyclohexane, methylcyclohexane or ethylcyclohexane; the aromatic hydrocarbons are selected from benzene, toluene or xylene; preferably, at the end of the polymerization reaction, the solid content (polypropylene copolymer product) in the system is 20%-60%.

[0044] The invention provides a polypropylene material, comprising a permeability enhancer and the above polypropylene resin or a polypropylene resin prepared by the above polypropylene resin preparation method.

[0045] Optionally, the polypropylene material provided by the present invention further includes an antioxidant, an acid scavenger and a permeability enhancer. The antioxidant, acid scavenger and permeability enhancer additives can be conventional additives in the industry without specific limitation. The corresponding additives can be selected and the dosage can be adjusted according to the needs of the actual application field; preferably, the polypropylene material recommended by the present invention includes the following components:

[0046] Polypropylene resin 99.55wt%-99.87wt%,

[0047] Antioxidant 0.05wt%-0.15wt%,

[0048] Acid scavenger 0.03wt%-0.10wt%,

[0049] Transmitter 0.05wt%-0.20wt%.

[0050] Optionally, the transmittance enhancer recommended by the present invention is NX8000;

[0051] The antioxidant is used to improve the processing stability and thermal oxidative aging resistance of the material, and is selected from phenolic antioxidants and / or phosphite antioxidants; preferably, the phenolic antioxidant is selected from tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol and / or 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate n-octadecyl alcohol, and the phosphite antioxidant is selected from one or more of bis(2,4-di-tert-butylphenol)pentaerythritol diphosphite and tris[2,4-di-tert-butylphenyl]phosphite;

[0052] The acid scavenger is calcium stearate.

[0053] The post-processing method of the polypropylene material provided by the present invention is not limited and can be conventionally used in the industry, such as mixing the polypropylene resin and the additives and then extruding and granulating them in a twin-screw extruder.

[0054] Compared with the prior art, the present invention has the following effects:

[0055] The existing preparation method of propylene / hexene copolymer generally adopts metallocene catalyst or conventional commercial Ziegler-Natta catalyst, combined with gas phase polymerization, mainly adopts pilot plant with multiple reactors in series, which is only applicable to pilot and industrial tests, and the process is complicated. The use of bulk polymerization has the problem that propylene / hexene copolymer is easily soluble in propylene monomer, resulting in the easy sticking of the polymerization product to the reactor. In the slurry polymerization process, propylene / hexene copolymer has the problem of swelling in the solvent and is easy to agglomerate. Therefore, in order to improve the low-temperature impact resistance of propylene / 1-hexene copolymer, most of them are improved on the basis of the existing gas phase polymerization method, such as controlling the monomer content, but the effect is not ideal. The inventor has jumped out of the limitation of the existing improvement direction, using a catalyst with high copolymerization performance, that is, a catalyst system containing a specific composite internal electron donor to control the hexene copolymerization amount and its distribution, combined with the solution polymerization method, significantly improving the low-temperature impact resistance of propylene / 1-hexene binary copolymer (i.e. polypropylene resin), and the obtained polypropylene material can meet the application requirements in the fields of medical tube materials, medical packaging and food packaging, injection molding products and other fields.

[0056] Beneficial effect 1: The polypropylene resin base material provided by the present invention has high impact strength, especially low-temperature impact strength (-20°C impact resistance can reach 3-7KJ / m 2 ), and its haze is also low below 30%. After adding a permeability enhancer to the polypropylene resin, the haze can be reduced to below 20%, which is suitable for pipe materials, packaging materials, etc. Adding antioxidants, acid scavengers and permeability enhancers to the polypropylene resin base material at the same time, the obtained polypropylene material has excellent low temperature resistance and impact resistance: (-20℃) is 3-7KJ / m 2, haze <15%, ash content 0.0038%-0.006%, melting point 145-155℃, with high low-temperature impact strength, high transparency and low ash content, which makes up for the shortcomings of the existing technology and can be used for the preparation of injection molded products in the fields of medical tube materials, medical packaging and food packaging that have high requirements on low-temperature impact and transparency.

[0057] Beneficial effect 2: The polypropylene resin provided by the present invention is prepared by a solution method. After the polymerization reaction is completed, the solvent can be recycled by flash evaporation, and a propylene-hexyl copolymer with good catalyst morphology replication can be obtained. The polymer has good fluidity, the particles do not stick together, and the polymer structure is not destroyed. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 This is the NMR carbon spectrum of the polypropylene material obtained in Example 1 of the present invention;

[0059] Figure 2 This is the DSC curve of the polypropylene material obtained in Example 1 of the present invention;

[0060] Figure 3 This is a polarized photograph of the polypropylene material prepared in Example 1 of the present invention;

[0061] Figure 4 This is a polarized photograph of the polypropylene material prepared in Comparative Example 4 of the present invention. DETAILED DESCRIPTION

[0062] The present invention is described in detail below by way of examples. It is necessary to point out that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Those skilled in the art in this field can make some non-essential improvements and adjustments to the present invention based on the above content of the present invention.

[0063] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0064] (I) Test method:

[0065] (1) Melting temperature (melting point):

[0066] The measurement was performed using a differential scanning calorimeter (DSC). The DSC model was Q2000, produced by PerkinElmer. The temperature was rapidly raised from 50°C to 200°C and kept constant for 5 minutes to eliminate the thermal history; the temperature was reduced to 50°C at a rate of 10°C / min and kept constant for 5 minutes to obtain the crystallization temperature Tc and crystallization enthalpy change ΔHc of the polymer; after keeping constant for 5 minutes, the temperature was raised to 200°C at 10°C / min to obtain the melting temperature Tm and melting enthalpy change ΔHm of the polymer.

[0067] Copolymer composition:

[0068] The chain microstructure of polypropylene was tested using a DMX 300M NMR spectrometer (produced by Bruker) using a temperature-increasing NMR technique. 80 mg to 100 mg of the copolymer was dissolved in 0.5 ml of deuterated o-dichlorobenzene reagent and heated to 383 K for NMR carbon spectrum scanning, with the number of scans being 3000.

[0069] Specimen preparation:

[0070] The standard specimens required for mechanical property testing are injected by SZ-15 hydraulic injection molding machine with an injection pressure of 100kgt / cm 3 , injection time 9.5 seconds, holding pressure 15 seconds, injection temperature 180°C. The injection molded specimens were placed in a desiccator at room temperature for more than 24 hours, and the notched impact specimens were milled with a standard notch on a notch type sample making machine, and continued to anneal in a desiccator at room temperature for more than 24 hours.

[0071] Impact strength test:

[0072] After the specimens were made according to the above preparation method, the notched impact strength of the samples was measured on a CSI-137C impact testing machine according to ASTM D256 standard. Low-temperature simply supported beam impact strength test: First, the sample with a standard notch milled was placed in a -20°C freeze drying oven for 2 hours for constant temperature cooling, and then its impact strength was quickly tested after being taken out.

[0073] Melt index test:

[0074] The test was conducted using a 556-0031 melt indexer from Haake, Germany, with a load of 2.16 kg and a temperature of 230°C.

[0075] Haze test:

[0076] The test was conducted using the EEL57D haze meter from the British company Diffusion, with a sample thickness of 1 mm.

[0077] Ethylene content test:

[0078] The test was conducted using a Nicolet iS50 Fourier infrared spectrometer from the American thermo scientific company.

[0079] Polarized light microscope:

[0080] The test was conducted using a BX 51 microscope from Japan's OLYMPUS company.

[0081] (II) Synthesis of dicarboxylic acid ester internal electron donor represented by formula I (the dicarboxylic acid ester internal electron donors in the following examples and comparative examples are all prepared by the following method)

[0082] The dicarboxylic acid ester internal electron donor is prepared by esterification reaction of the corresponding acid anhydride and alcohol. The reaction formula is as follows: specifically, dianhydride and isobutyl alcohol (as reactants and water-carrying agent) are used as reactants, concentrated sulfuric acid is added, stirred and heated until a water layer appears in the water separator, and the reaction is continued for 2 hours under stirring at this temperature. After the reaction is completed, it is washed with distilled water, 5wt% sodium carbonate solution, and saturated sodium chloride solution in sequence, and then dehydrated with calcium hydride and purified by reduced pressure distillation. After gas chromatography analysis, the corresponding dicarboxylic acid ester internal electron donor compound with a purity greater than 98% is obtained.

[0083]

[0084] Wherein, R1 and R2 are as defined above.

[0085] Example 1

[0086] This embodiment provides a polypropylene material, and a base polypropylene resin is prepared by a solution method. The specific preparation steps are as follows:

[0087] Heat a 5L autoclave to 70°C and evacuate and replace with nitrogen for three times to remove moisture and air in the autoclave and maintain a nitrogen atmosphere. Then, 80ml (55.2g) of 1-hexene monomer, 20mg of the main catalyst MgCl2 / ID / TiCl4, where ID is a mixture of cis+trans-1,2-cyclohexanedicarboxylic acid diisobutyl ester and 9,9-di(methylmethoxy)fluorene in a molar ratio of 1:1, 10ml of triethylaluminum hexane solution (0.88mmol / ml), 2ml of methylcyclohexyldimethoxysilane hexane solution (0.18mmol / ml) and 1L of anhydrous cyclohexane are added to the reactor in sequence, and then 170mmol of hydrogen and 500g (11.9mol) of propylene are introduced. The reactor was sealed and heated to 70°C and 4.0 MPa. After stirring for 1 hour, the stirring was stopped. After degassing and flash evaporation (flash evaporation temperature 220°C), a propylene / hexene copolymer (i.e., polypropylene resin) with a particle shape and good fluidity was obtained.

[0088] Weigh the raw materials according to the following weight ratio:

[0089] The above polypropylene resin 99.72%

[0090] Transparent agent NX80000 0.08%

[0091] Antioxidant (mass ratio of 1010 and 168 is 1:1) 0.15%

[0092] Acid scavenger calcium stearate 0.05%

[0093] After the above raw materials are mixed, they are added into a twin-screw extruder for extrusion granulation, and naturally cooled to room temperature to obtain a polypropylene material. The extruded melt temperature is 200°C and the screw speed is 100rpm. The performance test results of the polypropylene material are shown in Table 1.

[0094] Example 2

[0095] This example is similar to Example 1, except that the amount of 1-hexene monomer, solvent and flash temperature are different during the preparation of the polypropylene resin. The specific differences are as follows:

[0096] 1) The amount of 1-hexene monomer used in this example is 120 ml (138 g);

[0097] 2) The solvent in this embodiment is 1L of anhydrous toluene;

[0098] 3) The flash evaporation temperature in this embodiment is 240°C; other conditions are the same as those in Embodiment 1.

[0099] The obtained propylene / hexene copolymer particles have good morphology and fluidity. The performance test results of the obtained polypropylene material are shown in Table 1.

[0100] Example 3

[0101] This embodiment is similar to embodiment 1, except that the amount of solvent, hydrogen and additives used in the preparation process of polypropylene resin are different. The specific differences are as follows:

[0102] 1) The solvent in this embodiment is 1 L of anhydrous toluene;

[0103] 2) The amount of hydrogen used in this embodiment is 100 mmol;

[0104] 3) In this embodiment, polypropylene resin 99.8%, antioxidant (mass ratio of 1010 to 168 is 1:1)

[0105] 0.15%, acid scavenger calcium stearate 0.05%; other conditions are the same as in Example 1.

[0106] The obtained propylene / hexene copolymer particles have good morphology and fluidity. The performance test results of the obtained polypropylene material are shown in Table 1.

[0107] Example 4

[0108] This embodiment is similar to embodiment 2, except that the ID, solvent and flash temperature are different during the preparation of the polypropylene resin. The specific differences are as follows:

[0109] 1) ID in this example is a mixture of cis+trans-1,2-cyclohexanedicarboxylic acid diisobutyl ester and 9,9-di(methylmethoxy)fluorene in a molar ratio of 1:8;

[0110] 2) The solvent in this embodiment is 1 L of anhydrous cyclopentane;

[0111] 3) The flash evaporation temperature in this embodiment is 190°C; other conditions are the same as in Example 2.

[0112] The obtained propylene / hexene copolymer particles have good morphology and fluidity. The performance test results of the obtained polypropylene material are shown in Table 1.

[0113] Example 5

[0114] This embodiment is similar to embodiment 2, except that the ID, solvent and flash temperature are different during the preparation of the polypropylene resin. The specific differences are as follows:

[0115] 1) ID in this example is a mixture of cis+trans-1,2-cyclohexanedicarboxylic acid diisobutyl ester and 9,9-di(methylmethoxy)fluorene in a molar ratio of 9:1;

[0116] 2) The solvent in this example is 1 L of anhydrous n-heptane;

[0117] 3) The flash evaporation temperature in this embodiment is 240°C; other conditions are the same as in Example 2.

[0118] The obtained propylene / hexene copolymer particles have good morphology and fluidity. The performance test results of the obtained polypropylene material are shown in Table 1.

[0119] Example 6

[0120] This embodiment provides a polypropylene material, and a base polypropylene resin is prepared by a solution method. The specific preparation steps are as follows:

[0121] The 5L autoclave was heated to 90°C and the autoclave was evacuated and replaced with nitrogen, and the replacement was repeated three times to remove the moisture and air in the autoclave, and the nitrogen atmosphere was maintained. Then, 150ml (103.5g) of 1-hexene monomer, about 20mg of a solid catalyst prepared by MgCl2 / ID / TiCl4, wherein ID is a mixture of cis-4-cyclohexene-1,2-dicarboxylic acid diisobutyl ester and 9,9-di(methylmethoxy)fluorene in a molar ratio of 1:1, 10ml of a hexane solution of triethylaluminum (0.88mmol / ml), 2ml of a hexane solution of dicyclopentyldimethoxysilane (0.18mmol / ml), and 0.8L of anhydrous cyclohexane were added to the reactor in sequence, and then 50mmol of hydrogen and 500g (11.9mol) of propylene were introduced. The reactor was sealed and heated to 90°C. Stirring reaction was started at 4.0 MPa for 1 hour, then stirring was stopped. After degassing and flash evaporation (flash evaporation temperature 250°C), a propylene / hexene copolymer (i.e., polypropylene resin) with a particle shape and good fluidity was obtained.

[0122] Weigh the raw materials according to the following weight ratio:

[0123] The above polypropylene resin 99.72%

[0124] Transparent agent NX80000 0.08%

[0125] Antioxidant (mass ratio of 1010 to 168 is 1:1) 0.15%

[0126] Acid scavenger calcium stearate 0.05%

[0127] After the above raw materials are mixed, they are added into a twin-screw extruder for extrusion granulation, and naturally cooled to room temperature to obtain a polypropylene material. The extrusion temperature is 200°C and the screw speed is 100rpm. The performance test results of the polypropylene material are shown in Table 1.

[0128] Example 7

[0129] This example is similar to Example 6, except that the amount of 1-hexene monomer, solvent and flash temperature are different during the preparation of the polypropylene resin. The specific differences are as follows:

[0130] 1) The amount of 1-hexene monomer used in this example is 200 ml (138 g);

[0131] 2) The solvent in this embodiment is 1L of anhydrous toluene;

[0132] 3) The flash evaporation temperature in this embodiment is 230°C; other conditions are the same as those in Example 6.

[0133] The obtained propylene / hexene copolymer particles have good morphology and fluidity. The performance test results of the obtained polypropylene material are shown in Table 1.

[0134] Example 8

[0135] This embodiment is similar to embodiment 6, except that the amount of solvent, hydrogen and additives used in the preparation process of polypropylene resin are different. The specific differences are as follows:

[0136] 2) The solvent in this example is 1 L of anhydrous n-heptane;

[0137] 2) The amount of hydrogen used in this embodiment is 100 mmol;

[0138] 3) In this embodiment, the polypropylene resin is 99.8%, the antioxidant (the mass ratio of 1010 to 168 is 1:1) is 0.15%, and the acid scavenger calcium stearate is 0.05%; other conditions are the same as those in Example 6.

[0139] The obtained propylene / hexene copolymer particles have good morphology and fluidity. The performance test results of the obtained polypropylene material are shown in Table 1.

[0140] Example 9

[0141] This embodiment is similar to embodiment 6, except that the ID, solvent and flash temperature are different during the preparation of the polypropylene resin. The specific differences are as follows:

[0142] 1) ID in this example is a mixture of diisobutyl cis-4-cyclohexene-1,2-dicarboxylate and 9,9-di(methylmethoxy)fluorene in a molar ratio of 5:1;

[0143] 2) The solvent in this embodiment is 1 L of anhydrous cyclopentane;

[0144] 3) The flash evaporation temperature in this embodiment is 220°C; other conditions are the same as those in Example 6.

[0145] A propylene / hexene copolymer with a particle shape and good fluidity was obtained. The performance test results of the polypropylene material are shown in Table 1.

[0146] Comparative Example 1

[0147] This comparative example provides a polypropylene resin, which is prepared by a bulk method. The specific preparation steps are as follows:

[0148] The 5L high-pressure reactor was heated to 90°C and the reactor was evacuated and replaced with nitrogen, and the replacement was repeated three times to remove the moisture and air in the reactor and maintain a nitrogen atmosphere. Then 80ml (55.2g) of 1-hexene monomer, 20mg of the main catalyst MgCl2 / ID / TiCl4, where ID is a mixture of cis+trans-1,2-cyclohexanedicarboxylic acid diisobutyl ester and 9,9-di(methylmethoxy)fluorene in a molar ratio of 1:1, 10ml of triethylaluminum hexane solution (0.88mmol / ml) and 2ml of methylcyclohexyldimethoxysilane hexane solution (0.18mmol / ml) were added to the reactor in sequence, and then 170mmol of hydrogen and 500g (11.9mol) of propylene were introduced. The reactor was sealed and heated to 90°C and 4.0MPa. After stirring and reacting for 1h, stirring was stopped and unreacted propylene gas was discharged. The product polypropylene resin was in the form of a hard block and could not be discharged normally.

[0149] Comparative Example 2

[0150] This comparative example provides a polypropylene material, and a base polypropylene resin is prepared by a bulk method. The specific preparation steps are as follows:

[0151] The 5L high-pressure reactor was heated to 70°C and the reactor was evacuated and replaced with nitrogen. The replacement was repeated three times to remove the moisture and air in the reactor and maintain a nitrogen atmosphere. Then 80ml (55.2g) of 1-hexene monomer, 20mg of the main catalyst MgCl2 / ID / TiCl4, where ID is a mixture of cis+trans-1,2-cyclohexanedicarboxylic acid diisobutyl ester and 9,9-di(methylmethoxy)fluorene in a molar ratio of 1:1, 10ml of triethylaluminum hexane solution (0.88mmol / ml) and 2ml of methylcyclohexyldimethoxysilane hexane solution (0.18mmol / ml) were added to the reactor in sequence, and then 170mmol of hydrogen and 500g (11.9mol) of propylene were introduced. The reactor was sealed and heated to 70°C and 4.0MPa. After stirring the reaction for 1h, the stirring was stopped and the unreacted propylene gas was discharged. The catalyst morphology was not replicated, and the fluidity of the product polypropylene resin was extremely poor.

[0152] Weigh the raw materials according to the following weight ratio:

[0153] The above polypropylene resin 99.72%

[0154] Transparent agent NX80000 0.08%

[0155] Antioxidant (mass ratio of 1010 to 168 is 1:1) 0.15%

[0156] Acid scavenger calcium stearate 0.05%

[0157] After the above raw materials are mixed, they are added into a twin-screw extruder for extrusion granulation, and naturally cooled to room temperature to obtain a polypropylene material. The extrusion temperature is 200°C and the screw speed is 100rpm. The performance test results of the polypropylene material are shown in Table 1.

[0158] Comparative Example 3

[0159] This comparative example provides a polypropylene material, and a base polypropylene resin is prepared by a bulk method. The specific preparation steps are as follows:

[0160] A 5L high-pressure reactor was heated to 70°C and the reactor was evacuated and replaced with nitrogen, and the replacement was repeated three times to remove moisture and air in the reactor and maintain a nitrogen atmosphere. Then, 18.48g (0.66mol) of ethylene monomer, 20mg of the main catalyst MgCl2 / ID / TiCl4, where ID is a mixture of cis+trans-1,2-cyclohexanedicarboxylic acid diisobutyl ester and 9,9-di(methylmethoxy)fluorene in a molar ratio of 1:1, 10ml of triethylaluminum hexane solution (0.88mmol / ml) and 2ml of methylcyclohexyldimethoxysilane hexane solution (0.18mmol / ml) were added to the reactor in sequence, and then 170mmol of hydrogen and 500g (11.9mol) of propylene were introduced. The reactor was sealed and heated to 70°C and 4.0MPa. After stirring and reacting for 1h, stirring was stopped and unreacted ethylene gas was discharged to obtain a propylene / ethylene copolymer with a particle morphology and good fluidity.

[0161] Weigh the raw materials according to the following weight ratio:

[0162] The above polypropylene resin 99.72%

[0163] Transparent agent NX80000 0.08%

[0164] Antioxidant (mass ratio of 1010 to 168 is 1:1) 0.15%

[0165] Acid scavenger calcium stearate 0.05%

[0166] After the above raw materials are mixed, they are added into a twin-screw extruder for extrusion granulation, and naturally cooled to room temperature to obtain a polypropylene material. The extrusion temperature is 200°C and the screw speed is 100rpm. The performance test results of the polypropylene material are shown in Table 1.

[0167] Comparative Example 4

[0168] This comparative example provides a polypropylene material, and a base polypropylene resin is prepared by a solution method. The specific preparation steps are as follows:

[0169] 5L autoclave was heated to 70 ℃ and the reactor was evacuated and nitrogen replaced, replaced three times repeatedly, the moisture and air in the reactor were removed, and a nitrogen atmosphere was maintained. Then 80ml (55.2g) of 1-hexene monomer, 20mg of the main catalyst MgCl2 / ID / TiCl4, wherein ID is diisobutyl phthalate, 10ml of triethylaluminum hexane solution (0.88mmol / ml) and 2ml of methylcyclohexyldimethoxysilane hexane solution (0.18mmol / ml) and anhydrous cyclohexane 1L were added to the reactor in sequence, and then 170mmol of hydrogen and 500g (11.9mol) of propylene were introduced. The reactor was sealed and heated to 70 ℃, 4.0MPa, and after starting the stirring reaction for 1h, stirring was stopped, and after degassing and flash distillation (flash distillation temperature 220 ℃), a propylene / hexene copolymer with good particle form and fluidity was obtained.

[0170] Weigh the raw materials according to the following weight ratio:

[0171] The above polypropylene resin 99.72%

[0172] Transparent agent NX80000 0.08%

[0173] Antioxidant (mass ratio of 1010 to 168 is 1:1) 0.15%

[0174] Acid scavenger calcium stearate 0.05%

[0175] After the above raw materials are mixed, they are added into a twin-screw extruder for extrusion granulation, and naturally cooled to room temperature to obtain a polypropylene material. The extrusion temperature is 200°C and the screw speed is 100rpm. The performance test results of the polypropylene material are shown in Table 1.

[0176] Comparative Example 5

[0177] This comparative example provides a polypropylene material, and a base polypropylene resin is prepared by a solution method. The specific preparation steps are as follows:

[0178] Heat a 5L autoclave to 70°C and evacuate and replace with nitrogen for three times to remove moisture and air in the autoclave and maintain a nitrogen atmosphere. Then, 80ml (55.2g) of 1-hexene monomer, 20mg of the main catalyst MgCl2 / ID / TiCl4, where ID is 9,9-di(methylmethoxy)fluorene, 10ml of triethylaluminum hexane solution (0.88mmol / ml), 2ml of methylcyclohexyldimethoxysilane hexane solution (0.18mmol / ml) and 1L of anhydrous cyclohexane are added to the reactor in sequence, and then 170mmol of hydrogen and 500g (11.9mol) of propylene are introduced. The autoclave is sealed and heated to 70°C and 4.0MPa. After stirring for 1h, the reaction is stopped. After degassing and flash evaporation (flash evaporation temperature 220°C), a propylene / hexene copolymer with good fluidity and particle morphology is obtained.

[0179] Weigh the raw materials according to the following weight ratio:

[0180] The above polypropylene resin 99.72%

[0181] Transparent agent NX80000 0.08%

[0182] Antioxidant (mass ratio of 1010 to 168 is 1:1) 0.15%

[0183] Acid scavenger calcium stearate 0.05%

[0184] After the above raw materials are mixed, they are added into a twin-screw extruder for extrusion granulation, and naturally cooled to room temperature to obtain a polypropylene material. The extrusion temperature is 200°C and the screw speed is 100rpm. The performance test results of the polypropylene material are shown in Table 1.

[0185] Table 1

[0186]

[0187]

[0188] *Hexene content was calculated by NMR integration.

[0189] From the data in the above table, it can be seen that, compared with Comparative Examples 1-5, the polypropylene resin (propylene / 1-hexene copolymer base material) prepared in Examples 1-9, after adding antioxidants, acid scavengers and permeability enhancers, is extruded and granulated to obtain a low-temperature resistant, impact-resistant, transparent polypropylene material that meets the performance requirements. The low-temperature impact strength (-20°C) of the polypropylene material is 3-7KJ / m 2, haze <15%, ash content 0.0038%-0.006%, melting point 114-138°C; has the characteristics of low temperature impact strength, high transparency, low ash content, etc., fully meeting the needs of the medical field and food packaging market. Among them, in Example 3 and Example 8, no permeation enhancer was added, only antioxidant and acid scavenger were added, and the low temperature impact strength (-20°C) of the polypropylene material was 3.5KJ / m 2 and 6.9KJ / m 2 , haze <30%.

[0190] The propylene / 1-hexene copolymer prepared in Example 1 was subjected to NMR carbon spectrum detection, and the specific results are as follows: Figure 1 As shown, the polypropylene material prepared in Example 1 was subjected to DSC and polarization detection, and the specific results are as follows Figure 2 and Figure 3 The polypropylene material obtained in Comparative Example 4 was subjected to polarization detection, and the specific structure is as shown in Figure 4 As shown. Figure 1 The hexene content in the propylene / 1-hexene copolymer prepared in Example 1 can be calculated from the NMR carbon spectrum to be 3.4%. Figure 2 From the DSC curve, it can be seen that the melting point of the polypropylene material prepared in Example 1 is 137.9°C. Figure 3 and Figure 4 As can be seen from the polarized photos, compared with Comparative Example 4 ( Figure 4 ), the grain size of the polypropylene material prepared in Example 1 is smaller, and the transparency of the copolymer product is better.

[0191] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, technicians familiar with the field may make various corresponding changes and deformations based on the present invention, but these corresponding changes and deformations should all fall within the scope of protection of the claims of the present invention.

Claims

1. A polypropylene resin, characterized in that The polypropylene resin is a binary copolymer of propylene and 1-hexene, and has an impact strength of 3-7 KJ / m at -20°C. 2 .

2. A method for preparing the polypropylene resin according to claim 1, characterized in that: The solution polymerization method comprises the following steps: In a nitrogen atmosphere, 1-hexene monomer, titanium-containing Ziegler-Natta catalyst, solvent, chain transfer regulator and propylene are sequentially added into a polymerization kettle for polymerization, and after the polymerization reaction is completed, degassing and flash evaporation are performed to obtain the polypropylene resin; The titanium-containing Ziegler-Natta catalyst comprises a main catalyst, a co-catalyst and an external electron donor; the main catalyst comprises a composite internal electron donor, a halogen-containing magnesium compound and a titanium-containing compound, and the composite internal electron donor comprises a dicarboxylic acid ester compound and a 1,3-diether compound.

3. The preparation method according to claim 2, characterized in that: The dicarboxylic acid ester compound has a structure shown in Formula I, Wherein, R1 and R2 are independently selected from C1-C8 unsubstituted or substituted alkylene, C2-C8 straight or branched alkenylene, C5-C8 unsubstituted or substituted cycloalkenylene, C3-C8 unsubstituted or substituted cycloalkylene, or R1 and R2 together form a C5-C9 unsubstituted or substituted cyclic alkylene; preferably, R1 and R2 together form a C5-C9 unsubstituted or substituted cyclic alkylene; more preferably, R1 and R2 together form an unsubstituted or substituted cyclohexanedicarboxylic acid ester or cyclohexene-dicarboxylic acid ester; R3 and R4 are independently selected from C1-C10 unsubstituted or phenyl-substituted alkyl, unsubstituted or substituted phenyl, or unsubstituted or phenyl-substituted C2-C4 alkenyl; preferably, R3 and R4 are independently selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, phenyl, methylphenyl, ethylphenyl, n-propylphenyl, n-butylphenyl, isobutylphenyl, benzyl, phenethyl, phenylpropyl, phenylvinyl or phenylpropenyl.

4. The preparation method according to claim 2, characterized in that: The 1,3-diether compound has a structure shown in Formula II, Among them, R I and R II are independently selected from H, C1-C18 unsubstituted or substituted alkyl, C3-C18 cycloalkyl, C6-C18 unsubstituted or halogen-substituted aryl, or R I With R II Together they form a C9-C15 unsubstituted or substituted condensed cyclic hydrocarbon group, a C7-C12 bridged cyclic hydrocarbon, or a C5-C25 unsubstituted or substituted cycloolefin; preferably, the cycloalkyl group is selected from cyclohexyl or cyclopentyl, the condensed cyclic hydrocarbon is selected from any one of indene, fluorene, benzonaphthalene, naphthalene, anthracene, dihydronaphthalene and dihydroanthracene, the bridged cyclic hydrocarbon is selected from norbornadiene, and the cycloolefin is selected from cyclohexadiene, cyclopentadiene or cycloheptatriene; R III and R IV Each is independently selected from a C1-C4 alkyl group.

5. The preparation method according to claim 2, characterized in that: The general formula of the halogen-containing magnesium compound is MgX p R' 2-p , X is halogen, preferably chlorine or bromine; 0<p≤2, R' is selected from C1-C10 straight chain or branched alkyl, C1-C20 straight chain or branched alkoxy, C6-C10 aryl, or C6-C10 aryloxy; preferably, R' is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, n-octyl, phenyl, ethoxy, n-propyloxy, isopropyloxy, n-butyloxy, isobutyloxy, octyloxy or phenoxy.

6. The preparation method according to claim 2, characterized in that: The general formula of the titanium-containing compound is Ti(OR”) n X m , wherein R" is selected from C1-C10 straight or branched alkyl, preferably methyl, ethyl, n-propyl, isopropyl, n-butyl or isobutyl; X is halogen, preferably chlorine or bromine; n is 0, 1, 2, 3 or 4; n+m=3 or 4.

7. The preparation method according to claim 4, characterized in that: Taking the mass of the main catalyst as 100%, the following components are included: In the composite internal electron donor, the molar ratio of the dicarboxylic acid ester compound represented by formula I to the diether compound represented by formula II is (1-40):(40-1), preferably (1-20):(20-1), and more preferably (1-10):(10-1).

8. The preparation method according to claim 2, characterized in that: The co-catalyst is selected from one or more of alkyl lithium, alkyl magnesium, alkyl zinc, alkyl magnesium halide, alkyl aluminum, alkyl silicon, alkoxy silicon and alkyl silicon halide. Preferably, the co-catalyst is selected from alkyl aluminum and / or alkyl magnesium. More preferably, the co-catalyst is selected from trialkyl aluminum.

9. The preparation method according to claim 2, characterized in that: The general formula of the external electron donor is R a L R b H Si(OR c )4-d , where R a , R b R is independently selected from C1-C18 straight or branched alkyl, C5-C7 cycloalkyl or C6-C10 aryl; c Alkyl selected from C1-C4, d=1 or 2, 0≤L≤2, 0≤H≤2, and L+H+(4-d)=4, when d=1, L=0 or H=0.

10. The preparation method according to claim 2, characterized in that: The mass ratio of propylene to 1-hexene is 2-20:1; The chain transfer regulator is hydrogen. Preferably, the molar ratio of the chain transfer regulator to propylene is less than 0.

01.

11. The preparation method according to claim 2, characterized in that: The flash evaporation temperature is 150-270°C; The polymerization reaction pressure is 0.1-4.0 MPa, the reaction temperature is 70-150° C., preferably 90-120° C., and the reaction time is 0.5-3 h.

12. The preparation method according to claim 2, characterized in that: The solvent is selected from at least one of aliphatic hydrocarbons, alicyclic hydrocarbons and aromatic hydrocarbon solvents; preferably, the aliphatic hydrocarbon is selected from C6-C12 straight-chain alkanes or kerosene, the alicyclic hydrocarbon is selected from cyclopentane, cyclohexane, methylcyclohexane or ethylcyclohexane; the aromatic hydrocarbon is selected from benzene, toluene or xylene; preferably, at the end of the polymerization reaction, the solid content in the system is 20%-60%.

13. A polypropylene material, characterized in that: The polypropylene resin comprises the polypropylene resin according to claim 1 or the polypropylene resin prepared by the preparation method of the polypropylene resin according to any one of claims 2 to 12.

14. The polypropylene material according to claim 13, characterized in that It also includes a permeability enhancer, an antioxidant and an acid scavenger. Preferably, the polypropylene material includes the following components: Polypropylene resin 99.55wt%-99.87wt%, Antioxidant 0.05wt%-0.15wt%, Acid scavenger 0.03wt%-0.10wt%, Transmitter 0.05wt%-0.20wt%.

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