Transparent impact-resistant polypropylene product

Abstract

The invention relates to the technical field of transparent impact-resistant materials, in particular to a transparent impact-resistant polypropylene product. The xylene soluble content XS [%], the 23 DEG C simply supported beam impact strength IS [kJ.m <-2 >], the flexural modulus FM [MPa], the xylene soluble intrinsic viscosity IVXS [dL.g <-1 >], the melt index MFR [g.10 min <-1 >], the ethylene content ECXS [%] in the xylene soluble and the haze H [%] of the transparent anti-impact polypropylene product provided by the invention meet a certain relational expression. The transparent impact-resistant polypropylene product provided by the invention has excellent comprehensive properties, such as excellent impact property and optical property, and is suitable for the fields of refrigerated dairy product packaging, writing cases, snack outer packaging, small household appliance shells and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of transparent impact-resistant materials, and particularly to a transparent impact-resistant polypropylene product. Background Art

[0002] Polypropylene is a semi-crystalline polymer. Homopolypropylene has poor impact resistance and high brittleness. Therefore, many commercial polypropylenes are random copolymers containing 1-4% ethylene or impact copolymers with a higher ethylene content. Compared with homopolypropylene, random copolymer polypropylene has better transparency and impact resistance, but its impact resistance is inferior to that of impact copolymer polypropylene; due to the introduction of a certain amount of rubber phase components, impact copolymer polypropylene can greatly improve the impact resistance of polypropylene, but light will scatter and refract at the interface between the continuous phase and the rubber phase, resulting in a decrease in the transparency of impact copolymer polypropylene. Therefore, transparent impact copolymer polypropylene has distinct performance characteristics, that is, it combines the excellent optical properties of transparent polypropylene and the excellent impact resistance of impact polypropylene, and is mainly used in fields such as refrigerated dairy product packaging, stationery boxes, snack outer packaging, and small household appliance shells, such as refrigerated yogurt cups, yogurt lids, marker boxes, and snack storage boxes.

[0003] Due to the large market demand for transparent impact copolymer polypropylene and high requirements for product performance, how to further improve the performance of transparent impact-resistant polypropylene products is a current research hotspot for transparent materials. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a transparent impact-resistant polypropylene product, and the transparent impact-resistant polypropylene product provided by the present invention has excellent mechanical properties and optical properties.

[0005] The present invention provides a transparent impact-resistant polypropylene product, and the notched Izod impact strength at 23°C and the xylene-soluble content of the transparent impact-resistant polypropylene product satisfy formula (1), and the flexural modulus and the xylene-soluble content satisfy formula (2);

[0006] -0.1×XS + 9.5 ≤ IS ≤ -0.1×XS + 32.5 (1);

[0007] 7000×XS -0.85 ≤ FM ≤ 10000×XS -0.72 (2);

[0008] In formulas (1)-(2), XS is the xylene-soluble content, unit: wt%; IS is the notched Izod impact strength at 23°C, unit: kJ·m -2 ; FM is the flexural modulus, unit: MPa;

[0009] The melt index and the intrinsic viscosity of the xylene-soluble fraction of the transparent impact-resistant polypropylene product satisfy formula (3), the haze and the intrinsic viscosity of the xylene-soluble fraction satisfy formula (4), and the haze and the ethylene content in the xylene-soluble fraction satisfy formula (5);

[0010] IV XS 2 +12.75 ≤ MFR ≤ 240 × IV XS 3 (3);

[0011] H ≤ IV XS +14.5 (4);

[0012] H ≤ EC XS (5);

[0013] In formulas (3) to (5), IV XS is the intrinsic viscosity of the xylene-soluble fraction, unit: dL·g -1 ; MFR is the melt index, unit: g·10 min -1 ; H is the haze, unit: %; EC XS is the ethylene content in the xylene-soluble fraction, unit: wt%.

[0014] The xylene-soluble fraction content XS of the transparent impact-resistant polypropylene product of the present invention is preferably measured by a fully automatic polyolefin xylene-soluble fraction analyzer, using trichlorobenzene as the solvent; the measured value of the xylene-soluble fraction content is preferably 15 - 25 wt%, more preferably 16 - 24 wt%, and still more preferably 17 - 23 wt%.

[0015] The 23°C simply supported beam impact strength IS of the transparent impact-resistant polypropylene product of the present invention and the xylene-soluble fraction content XS satisfy the relationship of formula (1):

[0016] -0.1 × XS + 9.5 ≤ IS ≤ -0.1 × XS + 32.5 (1).

[0017] The transparent impact-resistant polypropylene product of the present invention has good impact resistance. When the relationship of IS ≥ -0.1 × XS + 9.5 in formula (1) is not satisfied, that is, when the simply supported beam impact strength is too small, the breakage rate of products in the fields of refrigerated dairy product packaging, stationery boxes, snack outer packaging, and small household appliance shells during storage, transportation, and application is relatively high, especially in low-temperature environments, and it cannot meet the requirements for damage when receiving impact forces such as in refrigerators and refrigerated drawers; when the relationship of IS ≤ -10 × XS + 32.5 in formula (1) is not satisfied, the product is not easily damaged, but the overall rigidity and transparency may be reduced.

[0018] The relational expressions satisfied by the transparent impact-resistant polypropylene product of the present invention are preferably: -0.1×XS + 13.5 ≤ IS ≤ -0.1×XS + 32.5, more preferably: -0.1×XS + 17.5 ≤ IS ≤ -0.1×XS + 32.5.

[0019] The Izod impact strength IS of the transparent impact-resistant polypropylene product of the present invention at 23°C is preferably measured by an Izod impact testing machine. According to GB / T 1043.1-2008, the specific test method is as follows: Select a pendulum of appropriate size, align the impact edge with the striking center of the specimen, lift the pendulum to the specified height and let it swing freely when testing, and pay attention to correcting the friction loss before testing. The ratio of the energy absorbed by the specimen at the time of failure after correction to the product of the width and thickness of the specimen is the Izod impact strength in formula (1), in kJ·m -2 as the unit.

[0020] The flexural modulus FM of the transparent impact-resistant polypropylene product of the present invention and the xylene-soluble content XS satisfy the relationship of formula (2):

[0021] 7000×XS -0.85 ≤ FM ≤ 10000×XS -0.72 (2).

[0022] The transparent impact-resistant polypropylene product of the present invention has good rigidity. When the relationship FM ≥ 700×XS in formula (2) -0.85 is not satisfied, that is, when the flexural modulus is too low, the overall rigidity of the processed product cannot be guaranteed, which may lead to low strength of the product during use; when the relationship FM ≤ 100×XS in formula (2) -0.72 is not satisfied, that is, when the flexural modulus is too high, the processing difficulty will increase significantly.

[0023] The relational expressions satisfied by the transparent impact-resistant polypropylene product of the present invention are preferably: 8000×XS -0.85 ≤ FM ≤ 10000×XS -0.72 and more preferably: 9000×XS -0.85 ≤ FM ≤ 10000×XS -0.72 .

[0024] The flexural modulus FM of the transparent impact-resistant polypropylene product of the present invention is preferably measured by a universal testing tensile machine using the three-point loading test method. According to GB / T 9341-2008, the specific test method is as follows: Use a universal testing tensile machine, and the specific test method is the three-point loading test method, that is, support the standard specimen as a cross beam, and make it at the center of the span (64 mm) at a constant speed (2 mm·min -1) Bend until the specimen breaks or the deformation reaches a predetermined value (6 mm), and measure the pressure applied to the specimen during this process. The ratio of the stress difference to the corresponding strain difference is the flexural modulus in Equation (2), in MPa.

[0025] The intrinsic viscosity IV of the xylene-soluble matter of the transparent impact-resistant polypropylene product of the present invention XS Preferably measured by a fully automatic polyolefin xylene-soluble matter analyzer, using trichlorobenzene as the solvent; the measured value of the intrinsic viscosity of the xylene-soluble matter is preferably 0.5 - 1.5 dL·g -1 , more preferably 0.6 - 1.4 dL·g -1 , still more preferably 0.7 - 1.3 dL·g -1 .

[0026] The melt flow rate MFR of the transparent impact-resistant polypropylene product of the present invention and the intrinsic viscosity IV of the xylene-soluble matter XS Satisfy the relationship of Equation (3):

[0027] IV XS 2 +12.75 ≤ MFR ≤ 240 × IV XS 3 (3).

[0028] The intrinsic viscosity of the xylene-soluble matter of the transparent impact-resistant polypropylene product of the present invention satisfies a certain relationship. When MFR ≥ IV in Equation (3) XS 2 +12.75 is not satisfied, that is, when the intrinsic viscosity of the xylene-soluble matter is too small, the rubber phase content of the copolymer product is too small, affecting the mechanical properties of the product; when MFR ≤ 240 × IV in Equation (3) XS 3 is not satisfied, that is, when the intrinsic viscosity of the xylene-soluble matter is too large, the rubber phase content of the copolymer product is too large, affecting the optical properties of the product.

[0029] The relationship satisfied by the transparent impact-resistant polypropylene product of the present invention is preferably: IV XS 2 +14.75 ≤ MFR ≤ 224 × IV XS 3 , more preferably: IV XS 2 +16.75 ≤ MFR ≤ 208 × IV XS 3 .

[0030] The melt flow rate MFR of the transparent impact-resistant polypropylene product of the present invention is preferably measured under a load of 2.16 kg and a test temperature of 230 °C. According to GB / T 3682.1-2018, the specific test method is as follows: Using a melt flow rate instrument, by calculating the mass of the molten copolymer product flowing through a die with a specified length of 8 mm and an inner diameter of 2.095 mm in 10 minutes under a load of 2.16 kg and a test temperature of 230 °C, that is, the melt flow rate in formula (3), in g·10min -1 as the unit.

[0031] The haze H of the transparent impact-resistant polypropylene product of the present invention and the intrinsic viscosity IV of the xylene-soluble matter XS satisfy the relationship of formula (4):

[0032] H ≤ IV XS +14.5 (4).

[0033] The transparent impact-resistant polypropylene product of the present invention has good optical properties. When the relationship of formula (4) is not satisfied, that is, when the haze is too high, the requirement of the product for transparent and beautiful appearance cannot be met.

[0034] The relational expression satisfied by the transparent impact-resistant polypropylene product of the present invention is preferably: H ≤ IV XS +12.5, more preferably: H ≤ IV XS +10.5.

[0035] The haze H of the transparent impact-resistant polypropylene product of the present invention is preferably measured by a haze meter. According to GB / T2410-2008, the specific test method is as follows: Measure the scattered light flux of the instrument and the specimen, the total transmitted light flux through the specimen, the scattered light flux of the instrument, and the incident light flux respectively. The data automatically calculated by the instrument is the haze in formula (4), expressed in %.

[0036] The ethylene content EC in the xylene-soluble matter of the transparent impact-resistant polypropylene product of the present invention XS is preferably measured by a fully automatic polyolefin xylene-soluble matter analyzer, using trichlorobenzene as the solvent; the measured value of the ethylene content in the xylene-soluble matter is preferably 15-30 wt%, more preferably 17-28 wt%, and still more preferably 19-26 wt%.

[0037] The haze H of the transparent impact-resistant polypropylene product of the present invention and the ethylene content EC in the xylene-soluble matter XS satisfy the relationship of formula (5):

[0038] H ≤ EC XS (5).

[0039] The transparent impact-resistant polypropylene product of the present invention has good optical properties. When the relationship of formula (5) is not satisfied, that is, when the haze is too high, the requirement of the product for transparent and beautiful appearance cannot be met.

[0040] The relational expression satisfied by the transparent impact-resistant polypropylene product of the present invention is preferably: H ≤ 0.9 × EC XS , more preferably: H ≤ 0.8 × EC XS .

[0041] The haze H in formula (5) is the same as the haze H in formula (4).

[0042] The monomers for preparing the transparent impact-resistant polypropylene product of the present invention preferably include propylene and ethylene, that is, the product contains a binary copolymer composed of repeating units corresponding to propylene and repeating units corresponding to ethylene.

[0043] The preparation process of the transparent impact-resistant polypropylene product of the present invention preferably includes a combined process of homopolymerization and / or random copolymerization and gas-phase copolymerization, and more preferably is prepared according to the following steps:

[0044] Monomers, Ziegler-Natta catalyst, alkylaluminum cocatalyst, external electron donor and hydrogen are added to a polymerization reactor; a combined process of homopolymerization and / or random copolymerization and gas-phase copolymerization is adopted to carry out polymer synthesis at a certain temperature and pressure; after the reaction is completed, unreacted monomers and hydrogen are removed by decompression to obtain transparent impact-resistant polypropylene powder; finally, various additives are added and the powder is granulated using a twin-screw extruder, and the obtained pellets are the transparent impact-resistant polypropylene product.

[0045] Preferably, the polymerization reactor includes but is not limited to one or more of a stainless steel pressure-resistant reactor, a tubular reactor, a stirred tank reactor, a multi-zone circulation reactor, a double-loop tubular reactor and a gas-phase reactor.

[0046] Furthermore, the Ziegler-Natta catalyst is a porous particulate or porous spherical catalyst containing a titanium compound with a magnesium halide as a carrier; the titanium compound is preferably any one of titanium tetrachloride, titanium tetrabromide and titanium tetraiodide; the magnesium halide is preferably any one of magnesium dichloride, magnesium dibromide and magnesium diiodide.

[0047] Furthermore, the alkylaluminum cocatalyst is an aluminum compound; the aluminum compound is preferably any one or more of triisobutylaluminum, triethylaluminum, dimethylaluminum chloride, diethylaluminum chloride and isobutyldichloroaluminum.

[0048] Further, the external electron donor is a silicon compound; the silicon compound is preferably any one or more of cyclohexylmethyl dimethoxysilane (C-Donor), cyclohexylmethyl trimethoxysilane, dicyclopentyl dimethoxysilane, dicyclohexyl dimethoxysilane, diisopropyl dimethoxysilane, and phenyl trimethoxysilane.

[0049] Further, the polymerization process is a two-stage polymerization process; one stage of the two-stage polymerization is a homopolymerization and / or random copolymerization process, and the second stage of polymerization is a gas-phase copolymerization process.

[0050] Further, the polymerization reaction temperature should be lower than the melting temperature of the copolymer, and the temperature range is preferably 10-90°C, more preferably 10-80°C.

[0051] Further, the transparent impact-resistant polypropylene product is a mixture, and the mixture contains additives; the additives are selected from any one or more of antioxidants, plasticizers, fillers, nucleating agents, and antistatic agents. Among them, the antioxidant preferably includes one or more of antioxidant 1010, antioxidant 3114, antioxidant 168, antioxidant DLTDP, and antioxidant DSTDP, and its mass content is preferably 0-2000 ppm; the filler preferably includes one or more of talc, calcium carbonate, wollastonite, kaolin, and silica, and its mass content is preferably 0-2000 ppm; the nucleating agent preferably includes one or more of nucleating agent 3988, nucleating agent NX8000, sodium benzoate, nucleating agent NA-21, and nucleating agent NA-11, and its mass content is preferably 0-3000 ppm; the antistatic agent preferably includes one or more of antistatic agent GMS90, antistatic agent GMS60, antistatic agent ABPS, antistatic agent SN, and antistatic agent LDN, and its mass content is preferably 0-1000 ppm.

[0052] In the specific embodiments provided by the present invention, the transparent impact-resistant polypropylene product can be specifically prepared according to the following steps:

[0053] a) Adding propylene monomer, Ziegler-Natta catalyst, alkylaluminum cocatalyst, and external electron donor into a prepolymerization reactor for prepolymerization reaction to obtain a prepolymerized slurry;

[0054] b) Continuously feeding the prepolymerized slurry into a first loop reactor and carrying out a polymerization reaction in the presence of hydrogen; subsequently, continuously feeding the slurry in the first loop reactor into a second loop reactor and continuing to carry out a polymerization reaction in the presence of hydrogen;

[0055] c) Continuously introduce the slurry in the second loop reactor into the gas-phase reactor, mix it with ethylene, propylene and hydrogen for gas-phase copolymerization reaction to obtain a crude propylene-ethylene copolymer;

[0056] d) Post-treat the crude propylene-ethylene copolymer to obtain a propylene-ethylene copolymer powder;

[0057] e) Melt-blend the propylene-ethylene copolymer powder with an additive and then extrude and pelletize to obtain a transparent impact-resistant polypropylene product.

[0058] In step a), the molar ratio of Ti in the Ziegler-Natta catalyst to Al in the alkyl aluminum cocatalyst is preferably 1:(100 - 200), more preferably 1:150; the mass ratio of the alkyl aluminum cocatalyst to the external electron donor is preferably (4 - 8):1, more preferably 6:1; the temperature of the prepolymerization reaction is preferably 10 - 30°C, more preferably 20°C.

[0059] In step b), the hydrogen concentration in the first loop reactor is preferably 1000 - 3000 ppm, more preferably 2000 ppm; the polymerization reaction temperature in the first loop reactor is preferably 60 - 80°C, more preferably 70°C; the polymerization reaction pressure in the first loop reactor is preferably 3 - 4 MPa, more preferably 3.8 MPa.

[0060] In step b), the hydrogen concentration in the second loop reactor is preferably 1000 - 3000 ppm, more preferably 2000 ppm; the polymerization reaction temperature in the second loop reactor is preferably 60 - 80°C, more preferably 70°C; the polymerization reaction pressure in the second loop reactor is preferably 3 - 4 MPa, more preferably 3.8 MPa.

[0061] In step c), the ratio of the molar amount of ethylene to the total molar amount of ethylene and propylene is preferably (0.1 - 0.2):1, more preferably (0.125 - 0.175):1; the ratio of the molar amount of hydrogen to the total molar amount of ethylene and propylene is preferably (0.01 - 0.03):1, more preferably 0.02:1; the temperature of the gas-phase copolymerization reaction is preferably 70 - 90°C, more preferably 80°C; the pressure of the gas-phase copolymerization reaction is preferably 1 - 2 MPa, more preferably 1.4 MPa.

[0062] Compared with the prior art, the beneficial effects of the present invention are:

[0063] The present invention provides a transparent impact-resistant polypropylene product, characterized in that the xylene-soluble content XS [%] of the polypropylene product is 15 - 25, and the Charpy impact strength IS [kJ·m at 23°C -2, the flexural modulus FM [MPa] and the xylene-soluble content respectively satisfy formulas (1) and (2); the intrinsic viscosity IV of the xylene-soluble matter XS [dL·g -1 is 0.5 to 1.5, and the melt flow rate MFR [g·10min -1 , the haze H [%] and the intrinsic viscosity of the xylene-soluble matter respectively satisfy formulas (3) and (4); the ethylene content EC of the xylene-soluble matter XS [%] is 15 to 30, and the haze H [%] and the ethylene content of the xylene-soluble matter satisfy formula (5).

[0064] After testing, the transparent impact-resistant polypropylene material that satisfies the above relationships has excellent comprehensive properties, such as excellent impact performance, excellent optical properties, high rigidity, and excellent processing performance. Detailed implementation manners

[0065] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0066] Example 1

[0067] Propylene monomer, Ziegler-Natta catalyst (a porous spherical catalyst with magnesium dichloride as the carrier and containing titanium tetrachloride, particle size range 30 - 100 μm), triethylaluminum, and an external electron donor (C-Donor) were added to a prepolymerization reactor. The titanium loading of the Ziegler-Natta catalyst was 2.24 wt%, and the Al / Ti molar ratio was maintained at 150, and the mass ratio of triethylaluminum to C-Donor was 6. The liquid-phase bulk prepolymerization reaction of propylene was carried out at a reaction temperature of 20 °C to make the prepolymerization multiple of the catalyst reach about 150 times. The prepolymerized slurry was continuously fed into the first loop reactor and subjected to a polymerization reaction in the presence of hydrogen, where the hydrogen concentration was 2000 ppm, the reaction temperature was 70 °C, and the reaction pressure was 3.8 MPa. The slurry in the first loop reactor was continuously fed into the second loop reactor and subjected to a polymerization reaction in the presence of hydrogen, and the reaction conditions were the same as those in the first loop reactor. The slurry in the second loop reactor was continuously fed into a gas-phase reactor and mixed with ethylene, propylene, and hydrogen for a gas-phase copolymerization reaction. The molar ratio of ethylene / (ethylene + propylene) was controlled at 0.125, and the molar ratio of hydrogen / (ethylene + propylene) was 0.02. The reaction temperature was 80 °C, and the reaction pressure was 1.4 MPa. Then, after processes such as degassing and recovery, flashing and drying, a propylene-ethylene copolymer powder was obtained. 500 ppm of antioxidant 1010, 1000 ppm of antioxidant 168, 1000 ppm of filler calcium carbonate, 2000 ppm of nucleating agent 3988, and 500 ppm of antistatic agent GMS90 were added to the propylene-ethylene copolymer powder, melt-blended, and then extruded into pellets. The pellets were injection-molded into standard specimens for comprehensive performance testing. The physical property evaluation results of the obtained copolymer are shown in Table 1.

[0068] Example 2

[0069] Propylene monomer, Ziegler-Natta catalyst (a porous spherical catalyst with magnesium dichloride as the carrier and containing titanium tetrachloride, particle size range 30 - 100 μm), triethylaluminum, and external electron donor (C-Donor) are added to the prepolymerization reactor. The titanium loading of the Ziegler-Natta catalyst is 2.24 wt%, and the Al / Ti molar ratio is maintained at 150, and the mass ratio of triethylaluminum to C-Donor is 6. The liquid-phase bulk prepolymerization reaction of propylene is carried out at a reaction temperature of 20 °C to make the prepolymerization multiple of the catalyst reach about 150 times. The prepolymerized slurry continuously enters the first loop reactor and undergoes a polymerization reaction in the presence of hydrogen, where the hydrogen concentration is 2000 ppm, the reaction temperature is 70 °C, and the reaction pressure is 3.8 MPa. The slurry in the first loop reactor continuously enters the second loop reactor and undergoes a polymerization reaction in the presence of hydrogen, and its reaction conditions are the same as those of the first loop reactor. The slurry in the second loop reactor continuously enters the gas-phase reactor and is mixed with ethylene, propylene, and hydrogen for a gas-phase copolymerization reaction. The molar ratio of ethylene / (ethylene + propylene) is controlled at 0.15, and the molar ratio of hydrogen / (ethylene + propylene) is 0.02. The reaction temperature is 80 °C, and the reaction pressure is 1.4 MPa. Then, through processes such as degassing and recovery, flash evaporation and drying, a propylene-ethylene copolymer powder is obtained. 500 ppm of antioxidant 1010, 1000 ppm of antioxidant 168, 1000 ppm of filler calcium carbonate, 2000 ppm of nucleating agent 3988, and 500 ppm of antistatic agent GMS90 are added to the propylene-ethylene copolymer powder, melt-blended, and then extruded into pellets. The pellets are injection-molded into standard specimens for comprehensive performance testing. The physical property evaluation results of the obtained copolymer are shown in Table 1.

[0070] Example 3

[0071] Propylene monomer, Ziegler-Natta catalyst (a porous spherical catalyst with magnesium dichloride as the carrier and containing titanium tetrachloride, particle size range 30 - 100 μm), triethylaluminum, and external electron donor (C-Donor) are added to the prepolymerization reactor. The titanium loading of the Ziegler-Natta catalyst is 2.24 wt%, and the Al / Ti molar ratio is maintained at 150, and the mass ratio of triethylaluminum to C-Donor is 6. The liquid-phase bulk prepolymerization reaction of propylene is carried out at a reaction temperature of 20 °C to make the prepolymerization multiple of the catalyst reach about 150 times. The prepolymerized slurry is continuously fed into the first loop reactor and undergoes a polymerization reaction in the presence of hydrogen, where the hydrogen concentration is 2000 ppm, the reaction temperature is 70 °C, and the reaction pressure is 3.8 MPa. The slurry in the first loop reactor is continuously fed into the second loop reactor and undergoes a polymerization reaction in the presence of hydrogen, and its reaction conditions are the same as those of the first loop reactor. The slurry in the second loop reactor is continuously fed into the gas-phase reactor and mixed with ethylene, propylene, and hydrogen for a gas-phase copolymerization reaction. The molar ratio of ethylene / (ethylene + propylene) is controlled to be 0.175, and the molar ratio of hydrogen / (ethylene + propylene) is 0.02. The reaction temperature is 80 °C, and the reaction pressure is 1.4 MPa. Then, through processes such as degassing and recovery, flash evaporation and drying, a propylene-ethylene copolymer powder is obtained. 500 ppm of antioxidant 1010, 1000 ppm of antioxidant 168, 1000 ppm of filler calcium carbonate, 2000 ppm of nucleating agent 3988, and 500 ppm of antistatic agent GMS90 are added to the propylene-ethylene copolymer powder, melt-blended, and then extruded into pellets. The pellets are injection-molded into standard specimens for comprehensive performance testing. The physical property evaluation results of the obtained copolymer are shown in Table 1.

[0072] Comparative Example 1

[0073] Propylene monomer, Ziegler-Natta catalyst (a porous spherical catalyst with magnesium dichloride as the carrier and containing titanium tetrachloride, particle size range 30 - 100 μm), triethylaluminum, and an external electron donor (C-Donor) are added to the prepolymerization reactor. The titanium loading of the Ziegler-Natta catalyst is 2.24 wt%, and the Al / Ti molar ratio is maintained at 150, and the mass ratio of triethylaluminum to C-Donor is 6. The liquid-phase bulk prepolymerization reaction of propylene is carried out at a reaction temperature of 20 °C to make the prepolymerization multiple of the catalyst reach about 150 times; the prepolymerized slurry is continuously fed into the first loop reactor and polymerization reaction is carried out in the presence of hydrogen, where the hydrogen concentration is 2000 ppm, the reaction temperature is 70 °C, and the reaction pressure is 3.8 MPa; the slurry in the first loop reactor is continuously fed into the second loop reactor and polymerization reaction is carried out in the presence of hydrogen, and the reaction conditions are the same as those of the first loop reactor; the slurry in the second loop reactor is continuously fed into the gas-phase reactor and gas-phase copolymerization reaction is carried out by mixing with ethylene, propylene, and hydrogen, controlling the molar ratio of ethylene / (ethylene + propylene) to be 0.15 and the molar ratio of hydrogen / (ethylene + propylene) to be 0.01, the reaction temperature is 80 °C, and the reaction pressure is 1.4 MPa; then, through processes such as degassing and recovery, flash evaporation and drying, etc., a propylene-ethylene copolymer powder is obtained; 500 ppm of antioxidant 1010, 1000 ppm of antioxidant 168, 1000 ppm of filler calcium carbonate, 2000 ppm of nucleating agent 3988, and 500 ppm of antistatic agent GMS90 are added to the propylene-ethylene copolymer powder, melt-blended and then extruded into pellets, and the pellets are injection-molded into standard specimens for comprehensive performance testing. The physical property evaluation results of the obtained copolymer are shown in Table 1.

[0074] Comparative Example 2

[0075] Propylene monomer, Ziegler-Natta catalyst (a porous spherical catalyst with magnesium dichloride as the carrier and containing titanium tetrachloride, particle size range 30 - 100 μm), triethylaluminum, and an external electron donor (C-Donor) are added to a prepolymerization reactor. The titanium loading of the Ziegler-Natta catalyst is 2.24 wt%, and the Al / Ti molar ratio is maintained at 150, and the mass ratio of triethylaluminum to C-Donor is 6. A liquid-phase bulk prepolymerization reaction of propylene is carried out at a reaction temperature of 20 °C to make the prepolymerization multiple of the catalyst reach about 150 times; the prepolymerized slurry is continuously fed into the first loop reactor and a polymerization reaction is carried out in the presence of hydrogen, where the hydrogen concentration is 2000 ppm, the reaction temperature is 70 °C, and the reaction pressure is 3.8 MPa; the slurry in the first loop reactor is continuously fed into the second loop reactor and a polymerization reaction is carried out in the presence of hydrogen, and its reaction conditions are the same as those of the first loop reactor; the slurry in the second loop reactor is continuously fed into a gas-phase reactor and mixed with ethylene, propylene, and hydrogen for a gas-phase copolymerization reaction, controlling the molar ratio of ethylene / (ethylene + propylene) to be 0.20 and the molar ratio of hydrogen / (ethylene + propylene) to be 0.02, with a reaction temperature of 80 °C and a reaction pressure of 1.4 MPa; then, through processes such as degassing and recovery, flash evaporation and drying, a propylene-ethylene copolymer powder is obtained; 500 ppm of antioxidant 1010, 1000 ppm of antioxidant 168, 1000 ppm of filler calcium carbonate, 2000 ppm of nucleating agent 3988, and 500 ppm of antistatic agent GMS90 are added to the propylene-ethylene copolymer powder, melt-blended and then extruded into pellets, and the pellets are injection-molded into standard specimens for comprehensive performance testing. The physical property evaluation results of the obtained copolymer are shown in Table 1.

[0076] Table 1

[0077] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Ethylene / (ethylene + propylene) molar ratio in the gas-phase reactor 0.125 0.15 0.175 0.15 0.20 Hydrogen / (ethylene + propylene) molar ratio in the gas-phase reactor 0.02 0.02 0.02 0.01 0.02 Xylene soluble content XS [%] 16.7 19.8 22.8 18.9 27.3 <![CDATA[Izod impact strength IS [kJ·m -2 > 16.2 24.3 28.8 22.5 36.4 Left side of formula (1) 7.8 7.5 7.2 7.6 6.8 Right side of formula (1) 30.8 30.5 30.2 30.6 29.8 Xylene soluble content XS [%] 16.7 19.8 22.8 18.9 27.3 Flexural modulus FM [MPa] 997.8 892.3 763.6 635.3 479.7 Left side of formula (2) 639.4 553.3 490.7 575.6 421.1 Right side of formula (2) 1317.2 1165.2 1052.7 1204.9 924.6 <![CDATA[Intrinsic viscosity IV of xylene soluble matter XS [dL·g -1 > 0.89 0.95 1.03 1.22 1.01 <![CDATA[Melt flow rate MFR [g·10min -1 > 24.5 25.8 28.4 27.7 33.4 Left side of formula (3) 13.5 13.7 13.8 14.2 13.8 Right side of formula (3) 169.2 205.8 262.3 435.8 247.3 <![CDATA[Intrinsic viscosity IV of xylene soluble matter XS [dL·g -1 > 0.89 0.95 1.03 1.22 1.01 Haze H [%] 11.3 13.1 13.9 16.5 18.5 Right side of formula (4) 15.4 15.5 15.5 15.7 15.5 <![CDATA[Ethylene content EC of xylene soluble matter XS [%]]]> 22.6 24.5 26.8 24.9 28.7 Haze H [%] 11.3 13.1 13.9 16.5 18.5 Right side of formula (5) 22.6 24.5 27.1 24.9 28.7

[0078] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art of this technology, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A transparent impact-resistant polypropylene product, characterized in that: The 23°C simply supported beam impact strength and xylene soluble content of the transparent impact-resistant polypropylene product satisfy the formula (1), and the flexural modulus and xylene soluble content satisfy the formula (2); -0.1×XS+9.5≤IS≤-0.1×XS+32.5 (1); 7000×XS -0.85 ≤FM≤10000×XS -0.72 (2); In formulas (1) to (2), XS is the xylene soluble content, unit: wt%; IS is the simply supported beam impact strength at 23°C, unit: kJ·m -2 ; FM is the bending modulus, unit: MPa; The melt index and xylene soluble intrinsic viscosity of the transparent impact-resistant polypropylene product satisfy formula (3), the haze and xylene soluble intrinsic viscosity satisfy formula (4), and the haze and ethylene content in xylene solubles satisfy formula (5); IV XS 2 +12.75≤MFR≤240×IV XS 3 (3); H≤IV XS +14.5 (4); H≤EC XS (5); In formulas (3) to (5), IV XS is the intrinsic viscosity of xylene soluble matter, unit: dL·g -1 ; MFR is the melt index, unit: g·10min -1 ; H is haze, unit: %; EC XS It is the ethylene content in xylene solubles, unit: wt%.

2. The transparent impact-resistant polypropylene product according to claim 1, characterized in that: The xylene soluble content is measured by a full-automatic polyolefin xylene soluble content analyzer, using trichlorobenzene as solvent; the measured value of the xylene soluble content is 15-25wt%.

3. The transparent impact-resistant polypropylene product according to claim 1, characterized in that: The 23°C simply supported beam impact strength is measured by a simply supported beam impact testing machine.

4. The transparent impact-resistant polypropylene product according to claim 1, characterized in that: The bending modulus is measured by a universal tensile testing machine using a three-point loading test method.

5. The transparent impact-resistant polypropylene product according to claim 1, characterized in that: The xylene soluble intrinsic viscosity is measured by a fully automatic polyolefin xylene soluble content analyzer, using trichlorobenzene as solvent; the measured value of the xylene soluble intrinsic viscosity is 0.5-1.5 dl·g -1 .

6. The transparent impact-resistant polypropylene product according to claim 1, characterized in that: The melt index is measured under a load of 2.16 kg and a test temperature of 230°C.

7. The transparent impact-resistant polypropylene product according to claim 1, characterized in that: The haze is measured by a haze meter.

8. The transparent impact-resistant polypropylene product according to claim 1, characterized in that: The ethylene content in the xylene solubles is measured by a fully automatic polyolefin xylene soluble content analyzer using trichlorobenzene as solvent; the measured value of the ethylene content in the xylene solubles is 15-30wt%.

9. The transparent impact-resistant polypropylene product according to any one of claims 1 to 8, characterized in that: The monomers for preparing the transparent impact-resistant polypropylene product include propylene and ethylene.

10. The transparent impact-resistant polypropylene product according to any one of claims 1 to 8, characterized in that: The process for preparing the transparent impact-resistant polypropylene product includes a process combining homopolymerization and / or random copolymerization with gas phase copolymerization.