A polypropylene resin and a method for producing the same, a polypropylene material

Abstract

The application discloses a polypropylene resin and a preparation method and polypropylene material thereof. 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 a solution polymerization method, and a Ziegler-Natta catalyst containing titanium is used, including a main catalyst, a cocatalyst and an external electron donor. The internal electron donor in the main catalyst includes a dibasic acid ester compound and a 1,3-diether compound. The polypropylene resin itself has high low-temperature impact strength and low haze. By adding an antioxidant, an acid remover and a transmittance enhancer into the polypropylene resin base at the same time, the prepared polypropylene material has the characteristics of high low-temperature impact strength, high transparency and low ash content, and can meet the preparation of injection-molded products in the fields of medical tube materials, medical packaging and food packaging, etc. which have high requirements on low-temperature impact and transparency.

Description

TECHNICAL FIELD

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

[0002] Isotactic polypropylene is severely limited in its application due to its brittleness and poor transparency. To expand the application range of polypropylene, random copolymerization of propylene and α-olefin is generally adopted to reduce the brittleness and improve the transparency of polypropylene. Existing random copolymerization polypropylene products mainly adopt copolymerization of ethylene and propylene, but the low molecular weight substances in the ethylene-propylene random copolymerization polypropylene are prone 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] Common α-olefins mainly include ethylene, 1-butene, 1-hexene and 1-octene, etc. With the transformation and upgrading of domestic refining business, long-chain α-olefins such as 1-hexene and 1-octene will gradually replace 1-butene to become a comonomer, and the polyolefin products produced have better performance and higher added value. Compared with propylene / ethylene copolymer, the melt strength, impact strength, transparency and weather resistance of propylene / 1-hexene copolymer can be significantly improved, and the crystallization of propylene / 1-hexene copolymer is smaller, the phase structure is more uniform, and the impact resistance is beneficial.

[0004] The preparation process of olefin copolymer 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 through catalysts at high temperature and high pressure, and 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 kind of precipitation polymerization, that is, the initiator of polymerization reaction and the formed polymer cannot be dissolved in the monomer itself and the solvent (diluent); the main function of the solvent added in slurry polymerization is to dilute the monomer concentration and discharge part of the reaction heat. Solution polymerization is to dissolve olefin monomers in alkane solvent 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 act 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 polymerization process of industrialized polybutene-1 mainly adopts gas phase method, bulk method and slurry method.

[0005] As disclosed in Chinese patent document CN201480058456.1, a multimodal propylene / 1-hexene copolymer having a content of 1-hexene-derived units of 0.6 wt% to 3.0 wt% is obtained in at least 2 connected gas-phase polymerization reactors using a Ziegler-Natta catalyst system, which is suitable for the production of industrial boards; the propylene / 1-hexene copolymer produced by this process has an impact strength at 0°C of 8 KJ / m 2 , a flexural modulus of 1520 MPa. Chinese patent document CN200880122494.3 discloses a propylene / 1-hexene copolymer obtained in at least 2 connected gas-phase polymerization reactors using a Ziegler-Natta catalyst system, which has a xylene-soluble fraction of less than 5% with respect to the total weight of the copolymer, which is particularly suitable for use in plastic tanks, in particular in blow-molded tanks.

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

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

[0008] Therefore, the existing propylene / 1-hexene copolymer mainly adopts a gas phase polymerization method, and according to different application requirements, the monomer hexene content and the gas phase polymerization parameters are adjusted to improve the mechanical properties, fluidity, transparency and the like in different degrees. However, the low-temperature impact resistance of the existing propylene / 1-hexene copolymer polypropylene material needs to be further improved, especially the polypropylene material for injection molding products in the fields of medical tube material, medical packaging and food packaging. The method of adjusting the monomer hexene content and the gas phase polymerization parameters is not ideal for further improving the low-temperature impact resistance of the propylene / 1-hexene copolymer polypropylene material. The performance of the polypropylene material is influenced by many factors, such as the selection of a high copolymerization performance catalyst, the selection of a polymerization process, the regulation of monomer content and the like, and these factors have an influence on a certain performance or comprehensive performance. Therefore, how to select a high copolymerization performance catalyst and further improve the low-temperature impact resistance of the propylene / 1-hexene copolymer to meet the application requirements of injection molding products in the fields of medical tube material, medical packaging and food packaging and the like is a technical problem to be solved at present. SUMMARY

[0009] In view of the problems existing in the prior art and the direction for improvement, the present application provides a polypropylene resin and a preparation method thereof, which controls the copolymerization amount and distribution of hexene by adopting a specific catalyst system in combination with a solution polymerization method, can significantly improve the low-temperature impact resistance of the propylene / 1-hexene copolymer, can meet the application requirements of injection molding products in the fields of medical tube material, medical packaging and food packaging and the like, and the method is simple in operation, good in stability and suitable for small-scale test, pilot test and industrial production.

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

[0011] The present application also provides a preparation method of the above polypropylene resin, which adopts a solution polymerization method and comprises the following steps:

[0012] 1-hexene monomer, a titanium-containing Ziegler-Natta catalyst, a solvent, a chain transfer regulator and propylene are sequentially added into a polymerization kettle for polymerization in a nitrogen atmosphere, and after the polymerization reaction is completed, the polypropylene resin is obtained through degassing and flashing;

[0013] The titanium-containing Ziegler-Natta catalyst comprises a main catalyst, a cocatalyst 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 dibasic acid ester compound and a 1,3-diether compound.

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

[0015]

[0016] Wherein, R1 and R2 are independently selected from C1-C8 unsubstituted or substituted alkylene groups, C2-C8 straight-chain or branched alkenyl groups, C5-C8 unsubstituted or substituted cycloalkenyl groups, C3-C8 unsubstituted or substituted cycloalkylene groups, or R1 and R2 together form C5-C9 unsubstituted or substituted cyclic alkylene groups; preferably, R1 and R2 together form C5-C9 unsubstituted or substituted cyclic alkylene groups; more preferably, R1 and R2 together form unsubstituted or substituted cyclohexanedicarboxylate or cyclohexene-dicarboxylate, such as cis+trans-1,2-cyclohexanedicarboxylate, cis-1,2-cyclohexanedicarboxylate, cis+trans-4-methyl-1,2-cyclohexanedicarboxylate, cis-4-cyclohexene-1,2-dicarboxylate, 1-cyclohexene-1,2-dicarboxylate, etc.

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

[0018] R3 and R4 are each independently selected from C1-C10 unsubstituted or phenyl-substituted alkyl groups, unsubstituted or substituted phenyl groups, or unsubstituted or phenyl-substituted C2-C4 alkenyl groups; 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, styryl or styrylyl.

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

[0021]

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

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

[0024] Preferably, the cycloalkyl is selected from cyclohexyl or cyclopentyl, the fused ring hydrocarbon is selected from any one of indene, fluorene, benzonaphthene, naphthalene, anthracene, dihydronaphthalene and dihydroanthracene, the bridged ring hydrocarbon is selected from norbornadiene, and the cyclic alkenyl is selected from cyclohexadiene, cyclopentadiene or cycloheptatriene.

[0025] The above definitions of R I and R II , "substituted" in "C9-C15 unsubstituted or substituted fused ring hydrocarbon" means that at least one H in the substituted fused ring hydrocarbon is replaced by halogen, C1-C6 branched or straight chain alkyl (such as methyl, ethyl, n-propyl, isopropyl, n-butyl, t-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 in the substituted alkyl is replaced 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 cyclic alkenyl" means that at least one H in the substituted cyclic alkenyl is replaced 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 polypropylene resin provided by the present invention, the 1,3-diether compound may 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 -(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-Bis(p-chlorophenyl)-1,3-dimethoxypropane, 2,2-bis(2-cyclohexylethyl)-1,3-dimethoxypropane, 2-methyl-2-isobutyl-1,3-dimethoxypropane, 2-methyl-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) ... Butyl)-2-sec-butyl-1,3-dimethoxypropane, 2,2-disec-butyl-1,3-dimethoxypropane, 2,2-di-tert-butyl-1,3-dimethoxypropane, 2,2-dineopentyl-1,3-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-dimethoxypropane3-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)-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-butylfluorene, 1,1-bis-(methoxymethyl)-2,5-cyclohexadiene, 1,1-bis-(methoxymethyl)-benzonaphthene, 7,7-bis-(methoxymethyl)-2,5-norbornadiene, 9,9-bis-(methoxymethyl)-1,4-methanodihydrobenzophenanthrene, 9,9-bis-(methoxymethyl)-1,4-methanodihydroanthracene, 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, and the like.

[0028] Optionally, in the method for preparing the polypropylene resin, the halogen-containing magnesium compound has a general formula of MgX p R' 2-p X is halogen, preferably chlorine or bromine; 0

[0029] Specifically, the halogen-containing magnesium compound is selected from magnesium chloride, magnesium bromide, Grignard reagent, or halogenated agent or obtained by reacting with halogen-free magnesium compound; the halogenated agent is selected from elemental iodine, chlorine, hydrogen chloride, SiCl4, CCl4, etc.; the Grignard reagent is selected from any one or several of methyl magnesium chloride, ethyl magnesium chloride, ethyl magnesium bromide, ethyl magnesium iodide, n-propyl magnesium chloride, n-propyl magnesium bromide, n-butyl magnesium chloride, n-butyl magnesium bromide, sec-butyl magnesium chloride, sec-butyl magnesium bromide, t-butyl magnesium chloride, t-butyl magnesium bromide, hexyl magnesium chloride, octyl magnesium chloride, pentyl magnesium chloride, iso-pentyl magnesium chloride, phenyl magnesium chloride, and phenyl magnesium bromide, etc.; the halogen-free magnesium compound is selected from alkyl magnesium, aryl magnesium, alkoxy magnesium compound, or aryloxy magnesium compound, specifically, any one or several of diethyl magnesium, di-n-propyl magnesium, di-iso-propyl magnesium, di-n-butyl magnesium, di-sec-butyl magnesium, di-t-butyl magnesium, dipentyl magnesium, n-butyl ethyl magnesium, n-butyl sec-butyl magnesium, n-butyl octyl magnesium, diphenyl magnesium, diethoxy magnesium, di-n-propyloxy magnesium, di-iso-propyloxy magnesium, di-n-butyloxy magnesium, di-sec-butyloxy magnesium, di-t-butyloxy magnesium, dipentyloxy magnesium, n-butyloxy ethoxy magnesium, n-butyloxy sec-butyloxy magnesium, n-butyloxy octyloxy magnesium, and diphenyloxy magnesium, etc.

[0030] Optionally, in the method for preparing the polypropylene resin, the titanium-containing compound has a general formula of Ti(OR") n X m R" is selected from C1-C10 straight chain or branched alkyl, preferably methyl, ethyl, n-propyl, iso-propyl, n-butyl, or iso-butyl; 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 several 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, etc.

[0032] Optionally, in the method for preparing the polypropylene resin provided by the present application, the components include the following percentages, based on 100% of the mass of the main catalyst:

[0033]

[0034]

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

[0036] Optionally, in the method for preparing the polypropylene resin provided by the present application, the cocatalyst is selected from one or several of alkyl lithium, alkyl magnesium, alkyl zinc, alkyl magnesium halide, alkyl aluminum, alkyl silicon, alkoxyl silicon and alkyl silicon halide; preferably, the cocatalyst is selected from alkyl aluminum and / or alkyl magnesium; more preferably, the cocatalyst is selected from trialkyl aluminum; specifically, the trialkyl aluminum includes any one or several of trimethyl aluminum, triethyl aluminum, triisobutyl aluminum, diethyl aluminum chloride, and C4-C6 cyclic alkyl aluminum, etc.

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

[0038] Specifically, the external electron donor may 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, tert-butyldimethoxysilane, etc. Cyclohexyl silane, tert-butylisobutyldimethoxysilane, tert-butyl(sec-butyl)dimethoxysilane, tert-butylpentyldimethoxysilane, tert-butylnonyldimethoxysilane, tert-butylhexyldimethoxysilane, tert-butylheptyldimethoxysilane, tert-butyloctyldimethoxysilane, tert-butyldecyldimethoxysilane, methyl tert-butyldimethoxysilane, cyclohexylmethyldimethoxysilane, cyclohexylethyldimethoxysilane, cyclohexylpropyldimethoxysilane, cyclohexylisobutyldimethoxysilane, dicyclohexyldimethoxysilane, cyclohexyltert-butyldimethoxysilane, cyclopentylmethyldimethoxysilane, cyclopentyl 2-methyl- ... The compound may be at least one of the following: oxysilane, pentyltrimethoxysilane, isopentyltrimethoxysilane, cyclopentyltrimethoxysilane, cyclohexyltrimethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, n-propyltrimethoxysilane, vinyltrimethoxysilane, tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, 2-ethylpiperidinyl-2-tert-butyldimethoxysilane, (1,1,1-trifluoro-2-propyl)-2-ethylpiperidinyldimethoxysilane, and (1,1,1-trifluoro-2-propyl)-methyldimethoxysilane. More preferably, the external electron donor compound may be at least one of dicyclopentyldimethoxysilane, diisopropyldimethoxysilane, diisobutyldimethoxysilane, cyclohexylmethyldimethoxysilane, methyltert-butyldimethoxysilane, and tetramethoxysilane.

[0039] Optionally, in the preparation method of 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 <0.01.

[0041] Optionally, in the method for preparing the polypropylene resin, the temperature of the flash is 150-270℃.

[0042] The pressure of the polymerization reaction is 0.1-4.0Mpa, the reaction temperature is 70-150℃, and the reaction time is 0.5-3h.

[0043] Optionally, in the method for preparing the polypropylene resin, the solvent is selected from at least one of the following: aliphatic hydrocarbon, alicyclic hydrocarbon and aromatic hydrocarbon solvents which are liquid at normal temperature and pressure; preferably, the aliphatic hydrocarbon is selected from C6-C12 straight chain alkane or kerosene, the alicyclic hydrocarbon is selected from cyclopentane, cyclohexane, methylcyclohexane or ethylcyclohexane, and the aromatic hydrocarbon is selected from benzene, toluene or xylene; preferably, the solid content (polypropylene copolymer product) in the system at the end of the polymerization reaction is 20%-60%.

[0044] The present application provides a polypropylene material, which comprises a transmittance enhancer and the polypropylene resin as described above or the polypropylene resin prepared by the method as described above.

[0045] Optionally, the polypropylene material provided by the present application further comprises an antioxidant, an acid scavenger and a transmittance enhancer. The additives such as the antioxidant, the acid scavenger and the transmittance enhancer can be selected according to the actual application field and the amount thereof can be adjusted, as long as they are conventional in the industry and are not specifically limited; preferably, the polypropylene material recommended by the present application comprises the following components in the following amounts:

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

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

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

[0049] transmittance enhancer 0.05wt%-0.20wt%.

[0050] Optionally, the transmittance enhancer recommended by the present application is NX8000.

[0051] The antioxidant is used to improve the processing stability and thermal oxygen aging of the material, and is selected from phenolic antioxidants and / or phosphite antioxidants; preferably, the phenolic antioxidant is selected from one or more of tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]pentaerythritol ester and / or 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid n-octadecyl ester, and the phosphite antioxidant is selected from bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite and tri[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 application is not limited, and conventional methods in the industry can be used, such as mixing the polypropylene resin and the additives uniformly and then performing extrusion granulation in a double-screw extruder.

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

[0055] The existing preparation method of propylene / hexene copolymer generally uses metallocene catalyst or conventional commercial Ziegler-Natta catalyst in combination with a gas phase polymerization method, mainly using a multi-kettle series pilot plant. This method is only suitable for pilot tests and industrial tests, and the process is complex. Using bulk polymerization has the problem that the propylene / hexene copolymer is easily dissolved in propylene monomer, resulting in easy sticking of the polymerization product. In the slurry polymerization process, the propylene / hexene copolymer has the problem of swelling in the solvent, which is easy to caking. Therefore, in order to improve the low-temperature impact resistance of propylene / 1-hexene copolymer, current improvements are mostly made on the basis of the existing gas phase polymerization method, such as controlling the monomer content, but the effect is not ideal. The present inventors have broken out of the limitations of the existing improvement direction, and used a catalyst with high copolymerization performance, i.e., a catalyst system containing a specific composite internal electron donor, to control the hexene copolymerization amount and its distribution, in combination with a solution polymerization method, which significantly improves the low-temperature impact resistance of propylene / 1-hexene binary copolymer (i.e., polypropylene resin), and the prepared polypropylene material can meet the application requirements in the fields of injection molding products in medical tube materials, medical packaging, food packaging, etc.

[0056] Beneficial effect 1: The polypropylene resin base provided by the present application itself has high impact strength, especially low-temperature impact strength (the impact resistance at -20℃ can reach 3-7 KJ / m 2 ), and the haze is also relatively low, below 30%. After adding the antireflection agent to the polypropylene resin, the haze can be reduced to below 20%, which is suitable for making tube materials, packaging materials, etc. The polypropylene material prepared by simultaneously adding the antioxidant, acid scavenger and antireflection agent to the polypropylene resin base has excellent low-temperature impact resistance: (-20℃) is 3-7 KJ / m 2Haze < 15%, ash content 0.0038%-0.006%, melting point 145-155 DEG C, having the characteristics of high low-temperature impact resistance, high transparency and low ash content, making up for the deficiencies of the prior art, and being applicable to the preparation of injection-molded products in the fields of medical tube materials, medical packaging and food packaging which have high requirements for low-temperature impact resistance and transparency.

[0057] Beneficial effect 2: The polypropylene resin provided by the application is prepared by a solution method, after the polymerization reaction is completed, the solvent is recycled by using a flash method, and the propylene hexene copolymer with good catalyst form replication is obtained, the polymer has good fluidity, the particles are not adhered to each other, and the polymer structure is not damaged. BRIEF DESCRIPTION OF DRAWINGS

[0058] Figure 1 NMR carbon spectrum of the polypropylene material prepared in Example 1 of the application;

[0059] Figure 2 DSC curve of the polypropylene material prepared in Example 1 of the application;

[0060] Figure 3 Polarized light photograph of the polypropylene material prepared in Example 1 of the application;

[0061] Figure 4 Polarized light photograph of the polypropylene material prepared in Comparative Example 4 of the application. DETAILED DESCRIPTION

[0062] The application will be described in detail below by means of examples. It is necessary to point out here that the following examples are only used for further illustrating the application, and cannot be understood as limiting the protection scope of the application, and the skilled in the art can make some non-essential improvements and adjustments to the application according to the above content of the application.

[0063] The specific experimental steps or conditions are not indicated in the examples, and the operations or conditions can be performed according to the conventional experimental steps described in the literature in the art. The reagents or instruments used are not indicated by the manufacturers, and are all conventional reagent products which can be obtained by purchase in the market.

[0064] (I) Test method:

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

[0066] Differential scanning calorimeter (DSC) was used for the determination. DSC model Q2000, produced by PerkinElmer company. Rapidly increase from 50℃ to 200℃, constant temperature for 5 min to eliminate thermal history; decrease to 50℃ at a rate of 10℃ / min, keep for 5 min to get the crystallization temperature Tc and crystallization enthalpy ΔHc of the polymer; keep for 5 min and then increase to 200℃ at a rate of 10℃ / min to get the melting temperature Tm and melting enthalpy ΔHm of the polymer.

[0067] Copolymer composition:

[0068] The chain microstructure of the polypropylene was tested by using temperature rising NMR technique on a NMR instrument model DMX 300M (produced by Bruker company). 80 mg-100 mg of the copolymer was dissolved in 0.5 ml of deuterated o-dichlorobenzene reagent, heated to 383 K for NMR carbon spectrum scanning, scanning times: 3000 times.

[0069] Sample preparation:

[0070] The standard sample for mechanical property test was prepared by using SZ-15 type hydraulic injection machine, injection pressure 100 kgt / cm 3 , injection time 9.5 seconds, holding pressure 15 seconds, injection temperature 180℃. The sample obtained by injection molding was placed in a desiccator at room temperature for more than 24 hours, and the notched impact sample was milled on a notched sample preparation machine, and then continued to be annealed in a desiccator at room temperature for more than 24 hours.

[0071] Impact strength test:

[0072] After the sample was prepared according to the above preparation method, the notched impact strength of the sample was determined according to ASTM D256 standard on a CSI-137C type impact testing machine. The low-temperature simply supported beam impact strength test first placed the sample with a standard notch in a-20℃ freeze-drying box for constant temperature for 2 hours for cooling, and then quickly tested the impact strength after taking out.

[0073] Melt index test:

[0074] Tested by using 556-0031 type melt index instrument of Germany Haake company, load 2.16 Kg, temperature 230℃.

[0075] Haze test:

[0076] Tested by using EEL57D haze meter of British Diffusion company, sample thickness 1 mm.

[0077] Ethylene content test:

[0078] The measurements were performed using a Nicolet iS50 Fourier transform infrared spectrometer from Thermo Scientific, USA.

[0079] Polarizing microscope:

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

[0081] (II) Synthesis of internal electron donors of dicarboxylic acid esters as shown in Formula I (the internal electron donors of dicarboxylic acid esters in the following examples and comparative examples are all prepared by the following method)

[0082] Internal electron donors of dicarboxylic acid esters are prepared by esterification of the corresponding acid anhydride and alcohol, as shown in the following reaction formula. Specifically, dianhydride and isobutanol (as reactants and dehydrating agents) are used as reactants, concentrated sulfuric acid is added, and the mixture is stirred and heated until an aqueous layer appears in the separator. The reaction is continued at this temperature for 2 hours. After the reaction is complete, the mixture is washed successively with distilled water, 5 wt% sodium carbonate solution, and saturated sodium chloride solution. After dehydration with calcium hydride, the mixture is purified by vacuum distillation. Gas chromatography analysis yields the corresponding internal electron donor compounds of diancarboxylic acid esters with a purity greater than 98%.

[0083]

[0084] The definitions of R1 and R2 are as described above.

[0085] Example 1

[0086] This embodiment provides a polypropylene material, which uses a solution method to prepare the base polypropylene resin. The specific preparation steps are as follows:

[0087] A 5L high-pressure reactor was heated to 70℃ and evacuated and purged with nitrogen three times to remove moisture and air, maintaining a nitrogen atmosphere. Then, 80ml (55.2g) of 1-hexene monomer, 20mg of the main catalyst MgCl2 / ID / TiCl4, a mixture of cis+trans-1,2-cyclohexanedicarboxylate and 9,9-di(methylmethoxy)fluorene in a molar ratio of 1:1, 10ml of triethylaluminum in hexane (0.88mmol / ml), 2ml of methylcyclohexyldimethoxysilane in hexane (0.18mmol / ml), and 1L of anhydrous cyclohexane were sequentially added to the reactor. Then, 170mmol of hydrogen and 500g (11.9mol) of propylene were introduced. The reactor was sealed and heated to 70℃ and 4.0MPa. After stirring for 1 hour, stirring was stopped. After degassing and flash evaporation (flash evaporation temperature 220℃), a propylene / hexene copolymer (i.e., polypropylene resin) with good particle morphology and flowability was obtained.

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

[0089] The above-mentioned polypropylene resin is 99.72%.

[0090] Brightening agent NX80000.08%

[0091] Antioxidant (1010 and 168 in a 1:1 mass ratio) 0.15%

[0092] Deacidifier: 0.05% calcium stearate

[0093] After mixing the above raw materials, the mixture was fed into a twin-screw extruder for extrusion granulation, and then naturally cooled to room temperature to obtain polypropylene material. The extruded melt temperature was 200℃, and the screw speed was 100 rpm. The performance test results of this polypropylene material are shown in Table 1.

[0094] Example 2

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

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

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

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

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

[0100] Example 3

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

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

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

[0104] 3) In this embodiment, the polypropylene resin is 99.8%, and the antioxidant (1010 and 168 in a mass ratio of 1:1) is used.

[0105] 0.15% of the acid remover calcium stearate and 0.05% of the acid remover; other conditions were the same as in Example 1.

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

[0107] Example 4

[0108] This example is similar to Example 2, except that the ID, solvent and flash temperature in the preparation process of the polypropylene resin are different, and the specific differences are as follows:

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

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

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

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

[0113] Example 5

[0114] This example is similar to Example 2, except that the ID, solvent and flash temperature in the preparation process of the polypropylene resin are different, and the specific differences are as follows:

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

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

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

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

[0119] Example 6

[0120] This example provides a polypropylene material, which is prepared by using a solution method to prepare a base polypropylene resin, and the specific preparation steps are as follows:

[0121] A 5L autoclave was heated to 90°C and vacuumed and replaced with nitrogen, repeated three times to remove water and air in the autoclave and maintain nitrogen atmosphere. Then 150ml (103.5g) of 1-hexene monomer, 20mg of solid catalyst prepared from MgCl2 / ID / TiCl4, wherein ID is a mixture of cis-4-cyclohexene-1,2-dicarboxylic acid diisobutyl ester and 9,9-bis(methylmethoxy)fluorene with a molar ratio of 1:1, 10ml of triethylaluminum solution in hexane (0.88mmol / ml) and 2ml of dicyclopentyl dimethoxysilane solution in hexane (0.18mmol / ml) and 0.8L of anhydrous cyclohexane were sequentially added into the reactor, and then 50mmol of hydrogen and 500g (11.9mol) of propylene were introduced. The autoclave was sealed and heated to 90°C, and the reaction was started under 4.0MPa after stirring for 1h, and then the stirring was stopped, and the product was obtained by degassing and flashing (flash temperature 250°C) to obtain propylene / hexene copolymer (i.e. polypropylene resin) with good particle morphology and flowability.

[0122] The raw materials were weighed according to the following proportions:

[0123] The polypropylene resin 99.72%

[0124] The antistatic agent NX8000 0.08%

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

[0126] The acid scavenger calcium stearate 0.05%

[0127] After mixing the above raw materials, they were extruded and granulated in a twin-screw extruder, and then naturally cooled to room temperature to obtain the polypropylene material. The extrusion temperature was 200°C and the screw rotation speed was 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, the solvent and the flash temperature in the preparation of the polypropylene resin are different, and the specific differences are as follows:

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

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

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

[0133] The obtained propylene / hexene copolymer has good particle morphology and flowability, and the performance test results of the obtained polypropylene material are shown in Table 1.

[0134] Example 8

[0135] This example is similar to Example 6, the difference is only in the solvent, hydrogen amount and additives in the preparation of the polypropylene resin, the specific differences are as follows:

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

[0137] 2) The hydrogen amount in this example is 100 mmol;

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

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

[0140] Example 9

[0141] This example is similar to Example 6, the difference is only in the ID, solvent and flash temperature in the preparation of the polypropylene resin, the specific differences are as follows:

[0142] 1) The ID in this example is a mixture of cis-4-cyclohexene-1,2-dicarboxylic acid diisobutyl ester and 9,9-bis(methylmethoxy)fluorene with a molar ratio of 5:1;

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

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

[0145] The obtained propylene / hexene copolymer particles have good morphology and flowability, and the performance test results of the obtained polypropylene material are shown in Table 1.

[0146] Comparative Example 1

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

[0148] A 5L autoclave was heated to 90°C and vacuumed and replaced with nitrogen three times to remove the water and air in the reactor and maintain a nitrogen atmosphere. Then 80ml (55.2g) 1-hexene monomer, 20mg of the main catalyst MgCl2 / ID / TiCl4, where ID is a mixture of cis+trans-1,2-cyclohexane dicarboxylic acid diisobutyl ester and 9,9-bis(methylmethoxy)fluorene with a molar ratio of 1:1, 10ml of triethylaluminum solution in hexane (0.88mmol / ml) and 2ml of methylcyclohexyldimethoxysilane solution in hexane (0.18mmol / ml) were added into 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, and the stirring reaction was started for 1h, then stopped, and the unreacted propylene gas was discharged. The product polypropylene resin was in a hard block shape and could not be normally discharged.

[0149] Comparative Example 2

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

[0151] A 5L autoclave was heated to 70°C and vacuumed and replaced with nitrogen three times to remove the water and air in the reactor and maintain a nitrogen atmosphere. Then 80ml (55.2g) 1-hexene monomer, 20mg of the main catalyst MgCl2 / ID / TiCl4, where ID is a mixture of cis+trans-1,2-cyclohexane dicarboxylic acid diisobutyl ester and 9,9-bis(methylmethoxy)fluorene with a molar ratio of 1:1, 10ml of triethylaluminum solution in hexane (0.88mmol / ml) and 2ml of methylcyclohexyldimethoxysilane solution in hexane (0.18mmol / ml) were added into 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, and the stirring reaction was started for 1h, then stopped, and the unreacted propylene gas was discharged. The catalyst morphology was not replicated, and the flowability of the product polypropylene resin was very poor.

[0152] The raw materials were weighed according to the following weight ratio:

[0153] The above polypropylene resin 99.72%

[0154] The above polypropylene resin 99.72%

[0155] The above polypropylene resin 99.72%

[0156] The above polypropylene resin 99.72%

[0157] After mixing the above raw materials, they were added into a twin-screw extruder for extrusion granulation, and then naturally cooled to room temperature to obtain the polypropylene material. The temperature for extrusion was 200°C, and the screw rotation speed was 100 rpm. 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 the 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 vacuumed and replaced with nitrogen, repeated for three times to remove the moisture and air in the reactor and maintain a nitrogen atmosphere. Then, 18.48g (0.66mol) of ethylene monomer, 20mg of main catalyst MgCl2 / ID / TiCl4 (where ID is a mixture of cis+trans-1,2-cyclohexane dicarboxylic acid diisobutyl ester and 9,9-bis(methylmethoxy)fluorene with a molar ratio of 1:1), 10ml of triethylaluminum solution in hexane (0.88mmol / ml), and 2ml of methylcyclohexyldimethoxysilane solution in hexane (0.18mmol / ml) were sequentially added into the reactor, and then 170mmol of hydrogen and 500g (11.9mol) of propylene were introduced. The reactor was sealed and heated to 70°C under 4.0MPa, and then the stirring was started for 1h, and then the stirring was stopped and the unreacted ethylene gas was discharged to obtain a propylene / ethylene copolymer with good flowability in the form of particles.

[0161] The raw materials were weighed according to the following weight ratio:

[0162] The above polypropylene resin 99.72%

[0163] The above polypropylene resin 99.72%

[0164] The above polypropylene resin 99.72%

[0165] The above polypropylene resin 99.72%

[0166] After mixing the above raw materials, they were added into a twin-screw extruder for extrusion granulation, and then naturally cooled to room temperature to obtain the polypropylene material. The temperature for extrusion was 200°C, and the screw rotation speed was 100 rpm. 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 the base polypropylene resin is prepared by a bulk method. The specific preparation steps are as follows:

[0169] A 5L high-pressure reactor was heated to 70℃ and evacuated and purged with nitrogen three times to remove moisture and air, maintaining a nitrogen atmosphere. Then, 80ml (55.2g) of 1-hexene monomer, 20mg of the main catalyst MgCl2 / ID / TiCl4 (ID being diisobutyl phthalate), 10ml of triethylaluminum in hexane (0.88mmol / ml), 2ml of methylcyclohexyldimethoxysilane in hexane (0.18mmol / ml), and 1L of anhydrous cyclohexane were sequentially added to the reactor. 170mmol of hydrogen and 500g (11.9mol) of propylene were then introduced. The reactor was sealed and heated to 70℃ and 4.0MPa. After stirring for 1 hour, stirring was stopped, and the mixture was degassed and flashed (at 220℃) to obtain a propylene / hexene copolymer with good particulate morphology and flowability.

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

[0171] The above-mentioned polypropylene resin is 99.72%.

[0172] Brightening agent NX80000.08%

[0173] Antioxidant (1010 and 168 in a 1:1 mass ratio) 0.15%

[0174] Deacidifier: 0.05% calcium stearate

[0175] After mixing the above raw materials, the mixture was fed into a twin-screw extruder for extrusion granulation, and then naturally cooled to room temperature to obtain the polypropylene material. The extrusion temperature was 200℃, and the screw speed was 100 rpm. The performance test results of this polypropylene material are shown in Table 1.

[0176] Comparative Example 5

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

[0178] A 5L autoclave was heated to 70°C and vacuumed and replaced with nitrogen, repeated three times to remove water and air in the reactor and keep nitrogen atmosphere. Then 80ml (55.2g) of 1-hexene monomer, 20mg of main catalyst MgCl2 / ID / TiCl4 (ID is 9,9-di(methylmethoxy)fluorene), 10ml of triethylaluminum hexane solution (0.88mmol / ml) and 2ml of methylcyclohexyldimethoxysilane hexane solution (0.18mmol / ml) and 1L of anhydrous cyclohexane were sequentially added into the reactor, 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, and then the stirring was started for 1h, and then stopped, and then degassed and flashed (flash temperature 220°C) to obtain a granular propylene / hexene copolymer with good flowability.

[0179] The raw materials were weighed according to the following proportions:

[0180] Polypropylene resin 99.72%

[0181] Transparency agent NX8000 0.08%

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

[0183] Antioxidant (mass ratio of 1010 to 168 is 1:1) 0.15%

[0184] The raw materials were mixed and then extruded and granulated in a twin-screw extruder, and then naturally cooled to room temperature to obtain the polypropylene material. The extrusion temperature was 200°C and the screw speed was 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 nuclear magnetic resonance 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 transparency agents and extruding and granulating, a low-temperature-resistant impact-resistant transparent polypropylene material meeting the performance requirements can be obtained. The low-temperature impact strength (-20°C) of the polypropylene material is 3-7KJ / m 2The material exhibits a haze of <15%, ash content of 0.0038%-0.006%, and a melting point of 114-138℃. It possesses characteristics such as low-temperature impact strength, high transparency, and low ash content, fully meeting the needs of the medical and food packaging markets. In Examples 3 and 8, no clarifying agent was added; only antioxidants and deacidifying agents were added. The low-temperature impact strength (-20℃) of this polypropylene material was 3.5 KJ / m². 2 and 6.9KJ / m 2 Haze < 30%.

[0190] The propylene / 1-hexene copolymer prepared in Example 1 was analyzed by carbon NMR spectroscopy, and the specific results are as follows: Figure 1 As shown, the polypropylene material obtained in Example 1 was subjected to DSC and polarized light detection, and the specific results are as follows. Figure 2 and Figure 3 As shown. The polypropylene material prepared in Comparative Example 4 was subjected to polarized light detection, and its specific structure is shown below. Figure 4 As shown. By Figure 1 The NMR carbon spectrum shows that the hexene content in the propylene / 1-hexene copolymer prepared in Example 1 is 3.4%. Figure 2 The DSC curve shows that the melting point of the polypropylene material prepared in Example 1 is 137.9℃. (From...) Figure 3 and Figure 4 The polarized photographs show that, compared to Comparative Example 4 ( Figure 4 The polypropylene material prepared in Example 1 has a smaller crystal size and the copolymer product has better transparency.

[0191] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A polypropylene resin, characterized in that, The polypropylene resin is a copolymer of propylene and 1-hexene, and its impact strength at -20℃ is 3-7 KJ / m. 2 ; The preparation method of the polypropylene resin adopts solution polymerization and includes the following steps: In a nitrogen atmosphere, 1-hexene monomer, titanium-containing Ziegler-Natta catalyst, solvent, chain transfer regulator and propylene are sequentially added to a polymerization reactor for polymerization. After the polymerization reaction is completed, the polypropylene resin is obtained by degassing and flash evaporation. The titanium-containing Ziegler-Natta catalyst includes a main catalyst, a co-catalyst, and an external electron donor; the main catalyst includes a composite internal electron donor, a halogen-containing magnesium compound, and a titanium-containing compound, wherein the composite internal electron donor includes a dicarboxylic acid ester compound and a 1,3-diether compound.

2. The polypropylene resin as described in claim 1, characterized in that, The dicarboxylic acid ester compounds have the structure shown in Formula I. R1 and R2 are independently selected from C1-C8 unsubstituted or substituted alkylene groups, C2-C8 straight-chain or branched alkenylene groups, C5-C8 unsubstituted or substituted cycloalkenylene groups, C3-C8 unsubstituted or substituted cycloalkenylene groups, or R1 and R2 together form C5-C9 unsubstituted or substituted cyclic alkylene groups. R3 and R4 are each independently selected from unsubstituted or phenyl-substituted alkyl groups of C1-C10, unsubstituted or substituted phenyl groups, or unsubstituted or phenyl-substituted alkenyl groups of C2-C4.

3. The polypropylene resin as described in claim 1, characterized in that, The 1,3-diether compounds have the structure shown in Formula II. Among them, R I and R II Each of the following is independently selected from H, C1-C18 unsubstituted or substituted alkyl groups, C3-C18 cycloalkyl groups, C6-C18 unsubstituted or halogen-substituted aryl groups, or R. I With R II Together they form unsubstituted or substituted fused ring hydrocarbons (C9-C15), bridged ring hydrocarbons (C7-C12), and unsubstituted or substituted cyclic alkenes (C5-C25); R III and R IV Alkyl groups selected independently from C1-C4.

4. The polypropylene resin as described in claim 1, characterized in that, The general formula of the halogen-containing magnesium compound is MgX. p R' 2-p X is a halogen; 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.

5. The polypropylene resin as described in claim 1, characterized in that, The general formula of the titanium-containing compound is Ti(OR”). n X m In the formula, R” is selected from C1-C10 straight-chain or branched alkyl groups; X is a halogen; n is 0, 1, 2, 3 or 4; n+m = 3 or 4.

6. The polypropylene resin according to claim 3, characterized in that, The main catalyst, by mass, comprises the following components in percentages: Magnesium 5.0wt%-50.0wt% Titanium 1.0wt%-8.0wt% Halogen 22.0wt%-70.0wt% The composite internal electron donor is 0.1 wt% - 20.0 wt%. In the composite internal electron donor, the molar ratio of the dicarboxylic acid ester compound and the diether compound shown in Formula II is (1-40):(40-1).

7. The polypropylene resin according to claim 1, characterized in that, The cocatalyst is selected from one or more of alkyllithium, alkylmagnesium, alkylzinc, alkylmagnesium halide, alkylaluminum, alkylsilicon, alkylsilicon oxide and alkylsilicon halide.

8. The polypropylene resin according to claim 1, characterized in that, The general formula for the external electron donor is R. a LR b H Si(OR c ) 4-d In the formula, R a R b Each is independently selected from C1-C18 straight-chain or branched alkyl groups, C5-C7 cycloalkyl groups, or C6-C10 aryl groups; R c Alkyl groups 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.

9. The polypropylene resin according to claim 1, characterized in that, The mass ratio of propylene to 1-hexene is 2-20:1; The chain transfer regulator is hydrogen.

10. The polypropylene resin according to claim 1, characterized in that, The flash evaporation temperature is 150-270℃; The polymerization reaction is carried out at a pressure of 0.1-4.0 MPa, a temperature of 70-150°C, and a time of 0.5-3 h.

11. The polypropylene resin according to claim 1, characterized in that, The solvent is selected from at least one of aliphatic hydrocarbons, alicyclic hydrocarbons, and aromatic hydrocarbon solvents.

12. The polypropylene resin according to claim 2, characterized in that, R1 and R2 together form C5-C9 unsubstituted or substituted cyclic hydrocarbon groups.

13. The polypropylene resin according to claim 12, characterized in that, R1, together with R2 and the ester group, forms an unsubstituted or substituted cyclohexanedicarboxylate or cyclohexene-dicarboxylate.

14. The polypropylene resin according to claim 2, characterized in that, R3 and R4 are each 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, styryl, or styrylpropenyl.

15. The polypropylene resin according to claim 3, characterized in that, The cycloalkyl group is selected from cyclohexyl or cyclopentyl, the fused cyclic hydrocarbon is selected from any one of indene, fluorene, benzonaphthalene, naphthalene, anthracene, dihydronaphthalene and dihydroanthracene, the bridged cyclic hydrocarbon is selected from norbornene, and the cyclic olefin is selected from cyclohexadiene, cyclopentadiene or cycloheptanetriene.

16. The polypropylene resin according to claim 4, characterized in that, X is chlorine or bromine.

17. The polypropylene resin according to claim 4, characterized in that, 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.

18. The polypropylene resin according to claim 5, characterized in that, "R" is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, or isobutyl.

19. The polypropylene resin according to claim 5, characterized in that, X is chlorine or bromine.

20. The polypropylene resin according to claim 6, characterized in that, The molar ratio of the dicarboxylic acid ester compound and the diether compound shown in Formula II is (1-20):(20-1).

21. The polypropylene resin according to claim 6, characterized in that, The molar ratio of the dicarboxylic acid ester compound and the diether compound shown in Formula II is (1-10):(10-1).

22. The polypropylene resin according to claim 7, characterized in that, The co-catalyst is selected from alkylaluminum and / or alkylmagnesium.

23. The polypropylene resin according to claim 22, characterized in that, The co-catalyst is selected from trialkylaluminum.

24. The polypropylene resin as described in claim 9, characterized in that, The molar ratio of the chain transfer regulator to propylene is <0.

01.

25. The polypropylene resin as described in claim 10, characterized in that, The polymerization reaction is carried out at a temperature of 90-120℃.

26. The polypropylene resin according to claim 11, characterized in that, The aliphatic hydrocarbon is selected from C6-C12 straight-chain alkanes or kerosene; the alicyclic hydrocarbon is selected from cyclopentane, cyclohexane, methylcyclohexane or ethylcyclohexane; and the aromatic hydrocarbon is selected from benzene, toluene or xylene.

27. The polypropylene resin according to claim 11, characterized in that, At the end of the polymerization reaction, the solid content in the system is 20%-60%.

28. A polypropylene material, characterized in that, Includes the polypropylene resin according to any one of claims 1-27.

29. The polypropylene material as described in claim 28, characterized in that, It also includes penetrating agents, antioxidants, and deacidifying agents.

30. The polypropylene material as described in claim 29, characterized in that, The polypropylene material comprises the following components in the following proportions: Polypropylene resin 99.55wt%-99.87wt%, Antioxidant 0.05wt%-0.15wt%, Acid remover 0.03wt%-0.10wt%, Brightening agent 0.05wt%-0.20wt%.

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