Polyolefin resin composition and method for producing the same, polyolefin resin product and respective applications thereof

Abstract

The application relates to the technical field of plastics, and discloses a polyolefin resin composition, a preparation method of the polyolefin resin composition, a polyolefin resin product and respective applications of the polyolefin resin product. The polyolefin resin composition contains polypropylene resin and composite nano-powder rubber nucleating agent; the polypropylene resin contains: (1) 75-90 parts by weight of homopolymer polypropylene A, wherein the isotactic pentad fraction is greater than or equal to 96%, the molecular weight distribution Mw / Mn is greater than or equal to 9.5, and the rheological distribution index PI is greater than or equal to 6.5; (2) 10-25 parts by weight of ethylene-propylene elastic copolymer B, wherein the content of ethylene structural units is 15-35 parts by weight; the content of the composite nano-powder rubber nucleating agent C is 0.1-0.8 parts by weight based on 100 parts by weight of the polypropylene resin; and the composite nano-powder rubber nucleating agent C contains 10-99 parts by weight of nano-powder rubber and 1-90 parts by weight of nucleating agent based on the total weight of the composite nano-powder rubber nucleating agent C. The polyolefin resin product provided by the application has high haze and high light transmittance and also has relatively high modulus.

Description

Technical Field

[0001] This invention relates to the field of plastics technology, specifically to a polyolefin resin composition and its preparation method, polyolefin resin products, and their respective applications. Background Technology

[0002] Polypropylene resin has been widely used in the automotive and home appliance industries due to its advantages of easy recycling, lightweight, and relatively low price, and is gradually replacing metals and engineering plastics. Taking automotive polypropylene as an example, polypropylene used in automotive interior parts needs extremely low volatile organic compound (VOC) content and high flowability and rigidity; polypropylene used in automotive bumpers needs extremely high impact resistance. The requirements for polypropylene materials vary significantly depending on the automotive component. With the development of new energy vehicles, automotive appearances are becoming increasingly diversified, emphasizing a technological feel. Consequently, automakers have raised new demands for automotive polypropylene materials, requiring them to possess high light transmittance and low haze characteristics in addition to the conventional properties of polypropylene.

[0003] Light transmittance and haze are two different optical parameters. Light transmittance refers to the ratio of the luminous flux transmitted through the sample to the incident luminous flux, while haze refers to the ratio of the scattered luminous flux transmitted through the sample but deviating from the incident light direction (2.5°) to the transmitted luminous flux. Light transmittance and haze are not positively correlated, and light transmittance is not equivalent to transparency.

[0004] Currently, most polypropylene materials with high light transmittance are transparent polypropylene, but the preparation of transparent polypropylene materials mainly relies on reducing haze. For homopolymer polypropylene, spherulites within the system cause deviation of incident light, increasing haze and thus reducing transparency. To reduce polypropylene haze, the main approach is to reduce the size of the spherulites or the dispersed phase, thereby minimizing the deviation of incident light. Adding antireflective nucleating agents can reduce spherulite size, thereby reducing haze and increasing transparency. Introducing comonomers into the polypropylene molecular chain disrupts the crystallization of the polypropylene molecular chain, reducing spherulite size; this is also why random copolymer polypropylene has high transparency. For impact-resistant polypropylene, reducing the dispersed phase size also reduces haze to some extent and increases transparency. Currently, methods to increase haze include adding light diffusing agents and fillers to polypropylene, but this may not only reduce light transmittance but also affect the mechanical properties of the polypropylene material.

[0005] CN104448538B discloses a polypropylene composition that combines high impact resistance and good transparency, containing 40-70% by weight of crystalline polypropylene A and 30-60% by weight of ethylene-propylene elastic copolymer B. The molecular weight distribution index of both the polypropylene composition and the crystalline polypropylene A is greater than 4, and the ratio of the melt index of the polypropylene composition to the melt index of the crystalline polypropylene A is 0.7-1.3. In the examples, the composition has a maximum haze of 36.3%, corresponding to a transmittance of 75.2%. This composition improves transparency by reducing the dispersed phase size; therefore, its low haze does not meet the required standards.

[0006] CN104448537B discloses a polypropylene composition with high impact resistance and good transparency, containing 70-95% by weight of crystalline polypropylene A and 5-30% by weight of ethylene-propylene elastic copolymer B. The molecular weight distribution index of both the polypropylene composition and the crystalline polypropylene A is greater than 4, and the ratio of the melt index of the polypropylene composition to the melt index of the crystalline polypropylene A is 0.7-1.3. The maximum haze of the composition in this patent is 55.2%, corresponding to a transmittance of 77.8%. This patent also improves transparency by reducing the dispersed phase size, therefore its haze is low and does not meet the requirements. Other patents for transparent impact-resistant polypropylene, such as CN1861674B and CN1380893A, do not provide haze data, and in practice, they are equivalent to replacing the main body of the impact-resistant polypropylene homopolymer with random copolymer polypropylene, resulting in a decrease in the rigidity, hardness, and heat distortion temperature of the final product. Furthermore, the use of a random copolymer reduces the spherulite grain size, suggesting that the material has lower haze. Patents CN14106453B and CN14106454B mention compositions with low haze and high gloss and transparency, which do not meet the requirement of high haze. Patent application CN114854136A discloses a polypropylene material with high haze and high light transmittance, mainly prepared by blending copolymerized polypropylene with additives such as β-crystal nucleating agents, nano zinc oxide, and nano barium sulfate, and the melt flow rate of the material is below 5 g / 10 min.

[0007] The analysis of the above patents reveals that existing polypropylene materials generally have low haze when meeting the requirements for light transmittance, and cannot simultaneously possess the characteristics of high light transmittance and high haze. Summary of the Invention

[0008] The purpose of this invention is to overcome the problem that existing polypropylene materials cannot simultaneously achieve high light transmittance and high haze. This invention provides a polyolefin resin composition and its preparation method, polyolefin resin products, and their respective applications. The polyolefin resin products made from the polyolefin resin composition provided by this invention have high haze and high light transmittance, as well as a high modulus.

[0009] To achieve the above objectives, the first aspect of the present invention provides a polyolefin resin composition comprising a polypropylene resin and a composite nanopowder rubber nucleating agent; Wherein, the polypropylene resin contains: (1) 75-90 parts by weight of homopolymer polypropylene A, which has an isotactic five-unit component fraction ≥96%, a molecular weight distribution Mw / Mn ≥9.5, and a rheological distribution index PI ≥6.5; (2) 10-25% by weight of ethylene-propylene elastic copolymer B, with the content of ethylene structural units being 15-35% by weight based on the total weight of ethylene-propylene elastic copolymer B. Based on 100 parts by weight of polypropylene resin, the content of composite nanopowder rubber nucleating agent is 0.1-0.8% by weight. Based on the total weight of the composite nanopowder rubber nucleating agent, it contains 10-99% by weight of nanopowder rubber and 1-90% by weight of nucleating agent.

[0010] A second aspect of the present invention provides a method for preparing a polyolefin resin composition, the method comprising: (1) Under the first olefin polymerization conditions, propylene monomer is contacted with Ziegler-Natta catalyst with high stereoselectivity, and unreacted monomer is removed from the mixture obtained after the contact reaction to obtain homopolymer polypropylene A. (2) Under the conditions of olefin gas-phase polymerization, ethylene monomer and propylene monomer are contacted and reacted with homopolymer polypropylene A obtained in step (1), and unreacted monomers are removed from the mixture obtained after the contact reaction to obtain a mixture containing homopolymer polypropylene A and ethylene-propylene elastic copolymer B. (3) The product obtained in step (2) is mixed with composite nanopowder rubber nucleating agent C, optionally antioxidant, optionally halogen absorber, melted and extruded into granules; In step (1), the molar ratio of hydrogen to propylene is 0.001-0.01:1; Based on the total weight of 100 parts by weight of homopolymer polypropylene A and ethylene-propylene elastic copolymer B, the amount of composite nanopowder rubber nucleating agent C is 0.1-0.8% by weight. Based on the total weight of the composite nanopowder rubber nucleating agent C, it contains 10-99% by weight of nanopowder rubber and 1-90% by weight of nucleating agent.

[0011] A third aspect of the present invention provides a polyolefin resin composition obtained by the method described in the second aspect above.

[0012] A fourth aspect of the present invention provides a polyolefin resin article made from the polyolefin resin composition described in the first or third aspect above.

[0013] The fifth aspect of the present invention provides the use of the polyolefin resin composition described in the first or third aspect above, or the polyolefin resin article described in the fourth aspect, in at least one of automobile bumpers, packaging boxes, and toys.

[0014] Through the above technical solutions, the polyolefin resin composition, its preparation method, and the polyolefin resin products provided by the present invention achieve the following beneficial effects: In this invention, a specific amount of homopolymer polypropylene A and ethylene-propylene elastic copolymer B are used, and the fraction of isotactic five-unit components of homopolymer polypropylene is controlled to be ≥96%, the molecular weight distribution Mw / Mn is ≥9.5, and the rheological distribution index PI is ≥6.5, which is beneficial to improving the light transmittance and flexural modulus of the final polyolefin resin product. Furthermore, controlling the type and content of composite nanopowder rubber nucleating agent is even more beneficial to improving the haze and flexural modulus of the final polyolefin resin product.

[0015] The polyolefin resin products produced by this invention, when measured according to GB / T2410-2008, have a haze of ≥80% and a light transmittance of ≥70% when the injection-molded sample is 2mm thick. Detailed Implementation

[0016] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0017] The first aspect of the present invention provides a polyolefin resin composition comprising a polypropylene resin and a composite nanopowder rubber nucleating agent; Wherein, the polypropylene resin contains: (1) 75-90 parts by weight of homopolymer polypropylene A, the fraction of its isotactic five-unit components is 96% or more, the molecular weight distribution Mw / Mn≥9.5, and the rheological distribution index PI≥6.5; (2) 10-25% by weight of ethylene-propylene elastic copolymer B, with the content of ethylene structural units being 15-35% by weight based on the total weight of ethylene-propylene elastic copolymer B. Based on 100 parts by weight of polypropylene resin, the content of composite nanopowder rubber nucleating agent is 0.1-0.8% by weight. Preferably, based on the total weight of the composite nanopowder rubber nucleating agent, it contains 10-99% by weight of nanopowder rubber and 1-90% by weight of nucleating agent.

[0018] In this invention, the contents of homopolymer polypropylene A and ethylene-propylene elastic copolymer B are determined using a Fourier transform infrared spectrometer.

[0019] In this invention, a specific amount of homopolymer polypropylene A and ethylene-propylene elastic copolymer B are used. The fraction of isotactic five-unit components of homopolymer polypropylene is controlled to be ≥96%, the molecular weight distribution Mw / Mn is ≥9.5 and the rheological distribution index PI is ≥6.5. The content of ethylene structural units in ethylene-propylene elastic copolymer B is controlled. A composite nanopowder rubber nucleating agent is added, which is beneficial to improving the haze, light transmittance and flexural modulus of the final polyolefin resin product.

[0020] More preferably, the content of homopolymer polypropylene A is 75-85 parts by weight.

[0021] More preferably, the isotactic five-unit component fraction of the homopolymer polypropylene A is ≥97%. The isotactic five-unit component fraction is also known as isotacticity, meaning a fact known to those skilled in the art. The isotactic five-unit component fraction is measured using a Bruker AVANCE 400 nuclear magnetic resonance spectrometer. 13 CNMR: 400 MHz, solvent: deuterated o-dichlorobenzene. Scanned more than 3000 times at 120 °C, with a 3-second interval between each scan.

[0022] More preferably, the molecular weight distribution of the homopolymer polypropylene A is Mw / Mn≥10.

[0023] In this invention, molecular weight distribution was analyzed using high-temperature gel permeation chromatography (GPC), specifically a PL-GPC220 high-temperature gel permeation chromatograph manufactured by Agilent Technologies, USA. The test temperature was 150℃, using three PLgel13 mOlexis columns with dimensions of 300.0 mm × 7.5 mm. The mobile phase was 1,2,4-trichlorobenzene (with 0.25 g / L of antioxidant 2,6-dibutyl-p-cresol), the flow rate was 1.0 mL / min, an IR5 infrared detector was used, the sample concentration was approximately 1 mg / mL, and a narrow-distribution polystyrene standard was used for universal calibration.

[0024] More preferably, the rheological distribution index PI of the homopolymer polypropylene A is ≥7.

[0025] In this invention, the rheological distribution index PI was characterized using a MARS60 rheometer from HAAKE GmbH, Germany. Specifically, the test temperature was 190℃, under a nitrogen atmosphere. The sample was prepared by compression molding at 190℃, with a diameter of 20mm and a thickness of 2mm. A dynamic frequency scan with small amplitude was performed on the sample at 190℃, with a frequency scan range of 0.1-100 rad / s. The values ​​were calculated according to equations (1) and (2): Rheological distribution index (PI) = 54.6 × (separation modulus) -1.76 (1) Wherein, separation modulus = (frequency at G′=500 Pa) / (frequency at G″=500 Pa), G′ is the storage modulus, and G″ is the loss modulus. (2) More preferably, the content of the ethylene-propylene elastic copolymer B is 15-25% by weight. More preferably, based on the total weight of the ethylene-propylene elastic copolymer B, the content of ethylene structural units is 20-30% by weight.

[0026] In this invention, the content of ethylene structural units in the ethylene-propylene elastic copolymer B is determined using a Fourier transform infrared spectroscopy (FTIR) instrument.

[0027] More preferably, based on 100 parts by weight of polypropylene resin, the content of composite nanopowder rubber nucleating agent is 0.2-0.5%.

[0028] More preferably, based on the total weight of the composite nanopowder rubber nucleating agent, it contains 20-90% by weight of nanopowder rubber and 10-80% by weight of nucleating agent.

[0029] In this invention, there is no particular limitation on the source of the composite nanopowder rubber nucleating agent; it can be commercially available or prepared using methods known in the art. For example, the composite nanopowder rubber nucleating agent can be commercial nucleating agents such as VP101B and VP101E purchased from Sinopec (Beijing) Chemical Research Institute Co., Ltd.

[0030] According to the present invention, preferably, the nanopowder rubber is selected from vulcanized powder rubber and / or non-vulcanized powder rubber.

[0031] According to some preferred embodiments of the present invention, the vulcanized powder rubber is selected from at least one of vulcanized natural rubber, vulcanized styrene-butadiene rubber, vulcanized nitrile rubber, vulcanized chloroprene rubber, vulcanized polybutadiene rubber, vulcanized polyacrylate rubber, vulcanized styrene-butadiene pyridine rubber, vulcanized isoprene rubber, vulcanized ethylene propylene rubber, and vulcanized polyurethane rubber, more preferably vulcanized styrene-butadiene rubber, and more preferably vulcanized carboxylated styrene-butadiene powder rubber.

[0032] In this invention, there is no particular limitation on the source of the vulcanized powder rubber; it can be commercially available or obtained using methods known in the art. Preferably, the preparation method of the vulcanized powder rubber may include adding or not adding a crosslinking agent to a rubber latex, followed by irradiation and drying to obtain the vulcanized powder rubber.

[0033] According to other preferred embodiments of the present invention, the non-vulcanized powder rubber is selected from at least one of cross-linked styrene-butadiene powder rubber, cross-linked polybutadiene powder rubber, cross-linked chloroprene powder rubber and cross-linked acrylate powder rubber, more preferably cross-linked styrene-butadiene powder rubber, and more preferably cross-linked carboxylated styrene-butadiene powder rubber.

[0034] In this invention, there are no special requirements regarding the source of the non-vulcanized powdered rubber; it can be commercially available or obtained using any method known in the art. Preferably, the preparation method of the non-vulcanized powdered rubber may include: using a cross-linked rubber emulsion as a raw material, and obtaining it after drying.

[0035] In this invention, there are no particular limitations on the source of the nucleating agent, which can be obtained commercially.

[0036] According to the present invention, preferably, the nucleating agent is an α-crystal nucleating agent and / or a β-crystal nucleating agent.

[0037] According to the present invention, preferably, the α-crystal nucleating agent is an aryl phosphate nucleating agent, preferably selected from at least one of 2,2'-methylene-bis(4,6-di-tert-butylphenyl)phosphate sodium, hydroxy-bis[2,2'-ethide-bis(4,6-di-tert-butylphenyl)phosphate aluminum] and hydroxy-bis[2,4,8,10-tetra(1,1'-dimethylethyl)-6-hydroxy-12H-dibenzo[d,g]dioxophosphatacyclo-6-oxo]aluminum, sodium 2,4,8,10-tetra-tert-butyl-12H-dibenzo[d,g][1,3,2]dioxaphosphatacyclooctadiene-6-acid salt 6-oxide and (1R,2S)-rel-1,2-cyclohexanedicarboxylate calcium salt (1:1).

[0038] In this invention, there is no particular limitation on the source of the α-crystal nucleating agent; it can be obtained from commercial purchases or prepared using methods known in the art.

[0039] In this invention, the type of β-crystal nucleating agent is not particularly limited and can be a conventional choice in the art. Preferably, the β-crystal nucleating agent is selected from at least one of polycyclic aromatic hydrocarbon β-crystal nucleating agents, organic acid β-crystal nucleating agents, organic salt β-crystal nucleating agents, amide β-crystal nucleating agents, rare earth β-crystal nucleating agents, and inorganic salt β-crystal nucleating agents, and preferably amide β-crystal nucleating agents and / or rare earth β-crystal nucleating agents.

[0040] In this invention, there is no particular limitation on the source of the β-crystal nucleating agent; it can be obtained from commercial purchases or prepared using methods known in the art.

[0041] In this invention, conventional additives in the art may be selectively added to the polyolefin resin composition as needed. Preferably, the polyolefin resin composition also contains antioxidants and / or halogen absorbers.

[0042] In this invention, the antioxidant can be a conventional choice in the art. Preferably, the antioxidant can be a hindered phenolic antioxidant or a phosphite antioxidant, or an antioxidant composed of a hindered phenolic antioxidant and a phosphite antioxidant in any proportion. The phosphite antioxidant can be, for example, tris[2,4-di-tert-butylphenyl] phosphite, and the hindered phenolic antioxidant can be, for example, pentaerythritol tetrakis[b-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0043] In this invention, the content of the antioxidant can be a conventional choice in the art, for example: based on 100 parts by weight of polypropylene resin, the content of the antioxidant is 0.05-0.5% by weight, preferably 0.1-0.4% by weight.

[0044] In this invention, there is no particular limitation on the type of halogen absorbent. Any halogen absorbent that can be used to eliminate halogens and residual catalysts in resin can be applied to this invention. Preferably, the halogen absorbent can be calcium stearate and / or hydrated talc.

[0045] In this invention, the content of the halogen absorbent can be a conventional selection in the art, for example: based on 100 parts by weight of polypropylene resin, the content of the halogen absorbent is 0.02-0.1% by weight, preferably 0.03-0.08% by weight.

[0046] According to the present invention, preferably, the melt mass flow rate of the polyolefin resin composition under a load of 2.16 kg at 230 °C is 30-80 g / 10 min.

[0047] In this invention, the melt flow rate of the polyolefin resin composition was tested according to GB / T 3682-2000, which will not be repeated below.

[0048] According to the present invention, preferably, the total content of ethylene structural units is 3-8% by weight, more preferably 4-7% by weight, based on the total weight of the polyolefin resin composition.

[0049] According to the present invention, preferably, the polyolefin resin composition further contains xylene solubles, the content of which is 10-25% by weight, for example, it can be 10% by weight, 11% by weight, 12% by weight, 13% by weight, 14% by weight, 15% by weight, 16% by weight, 17% by weight, 18% by weight, 19% by weight, 20% by weight, 21% by weight, 22% by weight, 23% by weight, 24% by weight, 25% by weight or any two of the above values ​​within the range.

[0050] In this invention, when the content of xylene-soluble substances in the polyolefin resin composition meets the above-mentioned range, the resulting polyolefin resin product has a high modulus, more preferably 12-18 by weight.

[0051] In this invention, the content of xylene-soluble substances in the polyolefin resin composition is determined according to GB / T24282 2009, and will not be repeated below.

[0052] According to the present invention, preferably, the intrinsic viscosity of xylene-soluble substances in the polyolefin resin composition is 1-1.5 dL / g. When the content of intrinsic viscosity of xylene-soluble substances in the polyolefin resin composition meets the above range, the resulting polyolefin resin product has a high modulus. In this invention, the intrinsic viscosity of the xylene-soluble component in the polyolefin resin composition was determined using a CRYSTEX instrument from PolymerChar, which will not be described in detail below.

[0053] According to the present invention, preferably, the intrinsic viscosity of the polyolefin resin composition is 1.3-2 dL / g.

[0054] In this invention, the intrinsic viscosity of the polyolefin resin composition was determined using a PolymerCharts CRYSTEX instrument. Specifically, trichlorobenzene solvent was used, and the mixture was heated to 150°C for dissolution. After holding the temperature for 90 minutes, a sample of the prepared polyolefin resin composition was taken for testing. The temperature was then lowered to 40°C and held for 70 minutes before further testing. The trichlorobenzene-soluble content obtained at 40°C was converted to the xylene-soluble content at room temperature according to GB / T 24282-2009 using a standard curve, which will not be elaborated further below.

[0055] A second aspect of the present invention provides a method for preparing a polyolefin resin composition, the method comprising: (1) Under the first olefin polymerization conditions, propylene monomer is contacted with Ziegler-Natta catalyst with high stereoselectivity, and unreacted monomer is removed from the mixture obtained after the contact reaction to obtain homopolymer polypropylene A. (2) Under the conditions of olefin gas-phase polymerization, ethylene monomer and propylene monomer are contacted and reacted with homopolymer polypropylene A obtained in step (1), and unreacted monomers are removed from the mixture obtained after the contact reaction to obtain a mixture containing homopolymer polypropylene A and ethylene-propylene elastic copolymer B. (3) The product obtained in step (2) is mixed with composite nanopowder rubber nucleating agent C, optionally antioxidant, optionally halogen absorber, melted and extruded into granules; In step (1), the molar ratio of hydrogen to propylene is 0.001-0.01:1; Based on the total weight of 100 parts by weight of homopolymer polypropylene A and ethylene-propylene elastic copolymer B, the amount of composite nanopowder rubber nucleating agent C is 0.1-0.8% by weight. Based on the total weight of the composite nanopowder rubber nucleating agent C, it contains 10-99% by weight of nanopowder rubber and 1-90% by weight of nucleating agent.

[0056] In this invention, by controlling the molar ratio of hydrogen to propylene in step (1), the amount of composite nanopowder rubber nucleating agent C, and the preparation of homopolymer polypropylene A and ethylene-propylene elastic copolymer B, the final polypropylene resin product can maintain high haze and high light transmittance while also having a high flexural modulus.

[0057] In this invention, in step (1), hydrogen acts as a chain transfer agent in the homopolymerization reaction, which has the function of adjusting the molecular weight and controlling the melt index of the product. By controlling the ratio of hydrogen to propylene to meet the above range, the homopolymer polypropylene A prepared in step (1) can have a higher melt index, and affect the intrinsic viscosity of the final polyolefin resin composition and the intrinsic viscosity of xylene solubles. More preferably, the molar ratio of hydrogen to propylene is 0.004-0.007:1.

[0058] In this invention, in step (2), the content of ethylene structural units in the ethylene-propylene elastic copolymer can be adjusted by adjusting the molar ratio of ethylene / (ethylene+propylene). When the molar ratio of ethylene / (ethylene+propylene) is too high, the light transmittance of the final polyolefin resin product will decrease. Therefore, it is necessary to control the molar ratio of ethylene / (ethylene+propylene) within a specific range. Preferably, the molar ratio of ethylene / (ethylene+propylene) is 0.05-0.3:1, and more preferably 0.08-0.2:1.

[0059] In this invention, in step (2), hydrogen is used as a chain transfer agent in the copolymerization reaction, which has the function of adjusting molecular weight and controlling the melt index of the product. By controlling the ratio of hydrogen to ethylene, the intrinsic viscosity of xylene solubles in the polyolefin resin composition can be further regulated. Preferably, the molar ratio of hydrogen to ethylene is 0.4-0.8:1, and more preferably 0.4-0.7:1.

[0060] In this invention, the gas molar ratio in the polymerization reactor in steps (1) and (2) is determined by gas chromatography, and will not be repeated below.

[0061] According to the present invention, preferably, the highly stereoselective Ziegler-Natta catalyst comprises: (i) a main catalyst comprising a product obtained by reacting a magnesium source, a titanium source and an internal electron donor; (ii) a co-catalyst; and (iii) an optional external electron donor.

[0062] According to the present invention, the magnesium element is sourced from a magnesium-containing support, which includes a magnesium chloride alcohol support and / or an alkoxy magnesium support. More preferably, the support is spherical.

[0063] Preferably, the magnesium chloride alcohol carrier comprises the components shown in formula (I). MgY1Y2·mR'OH(I) In formula (2), Y1 is selected from halogens, preferably from chlorine or bromine; Y2 is selected from halogens, alkyl or alkoxy; R' is selected from one of halogen-substituted or unsubstituted alkyl, halogen-substituted or unsubstituted cycloalkyl, halogen-substituted or unsubstituted aralkyl; m is 1-5; Preferably, the alkoxymagnesium support comprises the component shown in formula (II): [R1O] k Mg[OCH(CHXR2)(R 3 )] n (II) In formula (3), R1 is selected from one of straight-chain alkyl or halogen-substituted straight-chain alkyl, branched alkyl or halogen-substituted branched alkyl, cycloalkyl or halogen-substituted cycloalkyl; R2 and R3 are each independently one of hydrogen, straight-chain alkyl or halogen-substituted straight-chain alkyl, branched alkyl or halogen-substituted branched alkyl; X is a halogen; k is 0.1-1.9, n is 0.1-1.9, k+n=2; In this invention, the titanium source is preferably selected from titanium halide. More preferably, the titanium halide is selected from at least one of titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, titanium tetrabutoxy, titanium tetraethoxy, titanium monochlorotributoxy, titanium dichlorodibutoxy, titanium trichloromonobutoxy, titanium monochlorotriethoxy, titanium dichlorodiethoxy, titanium trichloromonoethoxy, and titanium trichloride, and more preferably titanium tetrachloride.

[0064] In a preferred embodiment of the present invention, the internal electron donor comprises a phosphate ester and / or an α-cyanosuccinate.

[0065] In this invention, the preferred molar ratio of the phosphate ester and α-cyanosuccinate is 1:15-500.

[0066] In this invention, the phosphate ester and α-cyanosuccinate are used in combination, and when the molar ratio of phosphate ester and α-cyanosuccinate meets the above-mentioned range, the rigidity-toughness balance of the polymer can be improved, and the molecular weight distribution (Mw / Mn) of homopolymer polypropylene can be improved. More preferably, the molar ratio of phosphate ester and α-cyanosuccinate is 1:40-400.

[0067] The inventors of this invention further discovered that using a combination of phosphate ester, α-cyanosuccinate and dialkoxy-substituted alkanes as internal electron donors can not only improve the molecular weight distribution (Mw / Mn) of the polymer, but also further enhance the activity of the polymerization reaction.

[0068] In another preferred embodiment of the present invention, the internal electron donors include phosphate esters, α-cyanosuccinates, and alkoxy-substituted alkanes.

[0069] In this invention, the preferred molar ratio of the phosphate ester, α-cyanosuccinate, and dialkoxysubstituted alkane is 1:10-250:20-100, and more preferably 1:200-250:50-100.

[0070] In this invention, the phosphate ester preferably includes at least one of a hydrocarbon ester of phosphoric acid, a halohydrocarbon ester of phosphoric acid, a hydrocarbon ester of phosphorous acid, and a halohydrocarbon ester of phosphorous acid; preferably, it is a hydrocarbon ester of phosphoric acid; more preferably, the hydrocarbon ester of phosphoric acid includes at least one of a monohydrocarbon ester of phosphoric acid, a dihydrocarbon ester of phosphoric acid, and a trihydrocarbon ester of phosphoric acid, more preferably triC1-C phosphate. 10 Alkyl ester; more preferably, the triC1-C phosphate 10 Alkyl esters include at least one of tributyl phosphate, trimethyl phosphate, triethyl phosphate, and tripropyl phosphate.

[0071] In this invention, the preferred molar ratio of the phosphate ester to the magnesium source is 0.0002-0.002:1, wherein the magnesium source is calculated as elemental magnesium.

[0072] In this invention, α-cyanosuccinate includes substituted and unsubstituted α-cyanosuccinate, wherein the α-cyanosuccinate has the structure shown in formula (3): (1) In equation (1), R a R b Each is independently selected from C1-C 10Straight-chain alkyl, C3-C 10 Branched alkyl, C3-C 10 cycloalkyl, C6-C 10 Aryl, C7-C 10 Alkyl or C7-C 10 Aryl alkyl; R c and R d Each is independently selected from H, C1-C 10 Straight-chain alkyl, C3-C 10 Branched alkyl, C3-C 10 cycloalkyl, C6-C 20 Aryl, C7-C 20 Alkyl or C7-C 20 Aromatic group.

[0073] In this invention, the α-cyanosuccinate is preferably selected from at least one of 2,3-diisopropyl-2-cyanosuccinate, 3-methyl-2-isopropyl-2-cyanosuccinate, 3-ethyl-2-isopropyl-2-cyanosuccinate, 3-propyl-2-isopropyl-2-cyanosuccinate, 3-butyl-2-isopropyl-2-cyanosuccinate, 3-phenyl-2-isopropyl-2-cyanosuccinate, 2,3-dicyclohexyl-2-cyanosuccinate, dibutyl 2,3-diisopropyl-2-cyanosuccinate, and 2-diisopropyl-3-cyclopentyl-2-cyanosuccinate.

[0074] In this invention, the molar ratio of the α-cyanosuccinate to the magnesium source is preferably 0.01-0.2:1, wherein the magnesium source is calculated as magnesium element, and is further preferably 0.03-0.15:1, more preferably 0.04-0.11:1.

[0075] In this invention, the preferred dialkoxylated alkane is 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-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-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)-2-isopropyl-1,3-dimethoxypropane, 2-isopropyl-2-isopentyl-1,3-dimethoxypropane, 2-phenyl-2-isopropyl-1,3-dimethoxypropane, 2-phenyl-2-sec-butyl-1,3-dimethyl At least one of the following: oxypropane, 2-benzyl-2-isopropyl-1,3-dimethoxypropane, 2-cyclopentyl-2-isopropyl-1,3-dimethoxypropane, 2-cyclopentyl-2-sec-butyl-1,3-dimethoxypropane, 2-cyclohexyl-2-isopropyl-1,3-dimethoxypropane, 2-cyclohexyl-2-sec-butyl-1,3-dimethoxypropane, 2-isopropyl-2-sec-butyl-1,3-dimethoxypropane, 2-cyclohexyl-2-cyclohexylmethyl-1,3-dimethoxypropane, and 9,9-bis(methoxymethyl)fluorene, preferably 2-isopropyl-2-isopentyl-1,3-dimethoxypropane and / or 9,9-bis(methoxymethyl)fluorene.

[0076] In this invention, the molar ratio of the diekoxy-substituted alkane to the magnesium source is preferably 0.001-0.15:1, wherein the magnesium source is calculated as magnesium element, and more preferably 0.01-0.1:1.

[0077] In this invention, there are no particular limitations on the order and conditions for preparing the main catalyst by mixing the magnesium source, titanium source and internal electron donor. The preferred steps include: (1) mixing the magnesium source and titanium source at a mixing temperature of -30°C to 0°C, preferably -25°C to -15°C; (2) heating the mixture in step (1) and adding the internal electron donor during the heating process, preferably heating to 80°C-120°C, preferably heating to 90°C-115°C.

[0078] In this invention, the co-catalyst is an organoaluminum compound, preferably an alkylaluminum compound, including but not limited to at least one of triethylaluminum, tripropylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-n-octylaluminum, diethylaluminum hydrogen, diisobutylaluminum hydrogen, diethylaluminum chloride, diisobutylaluminum chloride, sesquiethylaluminum chloride, and dichloroethylaluminum, more preferably a trialkylaluminum, such as at least one of triethylaluminum, tri-n-butylaluminum, and triisobutylaluminum.

[0079] In this invention, the external electron donor is preferably an organosilicon compound, preferably selected from at least one of cyclohexylmethyldimethoxysilane, diisopropyldimethoxysilane, di-n-butyldimethoxysilane, diisobutyldimethoxysilane, diphenyldimethoxysilane, methyl tert-butyldimethoxysilane, dicyclopentyldimethoxysilane, 2-ethylpiperidinyl-2-tert-butyldimethoxysilane, (1,1,1-trifluoro-2-propyl)-2-ethylpiperidinyldimethoxysilane, and (1,1,1-trifluoro-2-propyl)-methyldimethoxysilane.

[0080] According to the present invention, preferably, the molar ratio of the main catalyst to the co-catalyst is 1:15-720, more preferably 1:25-500; the main catalyst is calculated as titanium, and the co-catalyst is calculated as aluminum.

[0081] According to the present invention, preferably, the molar ratio of the main catalyst to the external electron donor is 1:1-120, more preferably 1:10-100; the main catalyst is calculated as titanium, and the external electron donor is calculated as silicon.

[0082] In this invention, there are no particular limitations on the mixing method of the components in the highly stereoselective Ziegler-Natta catalyst. During the preparation of the catalyst, the main catalyst, the co-catalyst, and the external electron donor can be mixed together and then added to the reaction, or the co-catalyst and the external electron donor can be pre-mixed and then mixed with the main catalyst before being added to the reaction.

[0083] In this invention, there are no particular limitations on the method of adding the highly stereoselective Ziegler-Natta catalyst. It can be added directly to the first olefin polymerization reactor, or it can be added to the first olefin polymerization reactor after pre-complexation and / or pre-polymerization. The terms "pre-complexation" and "pre-polymerization" as used refer to polymerization reactions carried out to achieve lower reaction rates and monomer conversion rates compared to those under normal polymerization conditions.

[0084] In this invention, the pre-complexation process can be carried out in a pre-complexation or pre-polymerization reactor with or without polymerizable monomers. When performing the pre-complexation reaction, the reactor can be a continuous stirred tank reactor, or other forms that achieve sufficient mixing, such as a loop reactor, a section of pipeline containing a static mixer, or even a section of pipeline where the material is in a turbulent state. There are no particular limitations on the pre-complexation conditions; preferably, the pre-complexation temperature is -10 to 60°C, more preferably 0 to 30°C; the pre-complexation time is 0.1 to 180 min, more preferably 5 to 30 min.

[0085] In this invention, step (1) further includes prepolymerizing the highly stereoselective Ziegler-Natta catalyst.

[0086] In this invention, the first olefin polymerization catalyst can be used directly or after pre-complexation for the prepolymerization reaction. There are no particular limitations on the reactor used for the prepolymerization reaction; it can be a reactor commonly used in the art, such as a continuous stirred tank reactor or a loop reactor. The prepolymerization reaction can be carried out continuously in bulk liquid conditions or intermittently in an inert solvent.

[0087] In this invention, there are no particular limitations on the prepolymerization conditions. Preferably, the prepolymerization temperature is -10 to 60°C, more preferably 0 to 40°C; the time is 0.5 to 5 hours, more preferably 1.4 to 6 hours; and the prepolymerization ratio is 0.5 to 1000 times, more preferably 1 to 500 times. "Prepolymerization ratio" refers to the ratio of the mass of polymer produced in the prepolymerization reactor to the mass of the catalyst.

[0088] In this invention, the first olefin polymerization reaction can be carried out continuously or intermittently. Continuous polymerization can use two or more reactors in series. There are no particular limitations on the reactor for the first olefin polymerization reaction; it can be a liquid-phase reactor or a gas-phase reactor. The liquid-phase reactor can be a loop reactor or a stirred tank reactor, and the gas-phase reactor can be at least one of a horizontal stirred bed reactor, a vertical stirred bed reactor, a fluidized bed reactor, or a multi-zone circulating reactor.

[0089] According to the present invention, preferably, the first olefin polymerization reaction can be liquid-phase or gas-phase polymerization, and there are no particular limitations on the conditions of the first olefin polymerization reaction. When the first olefin polymerization is a liquid-phase polymerization, preferably, the polymerization temperature is 0-150℃, which can be any two of the following ranges: 0℃, 10℃, 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, 100℃, 120℃, 140℃, 150℃, or values ​​within that range, preferably 40-100℃. There is no particular limitation on the polymerization pressure of the first olefin, as long as the polymerization pressure is higher than the saturated vapor pressure of propylene at the corresponding polymerization temperature, preferably 2-10 MPaG. The residence time is 0.5-5 h, preferably 1-2 h. When the first olefin polymerization is a gas-phase polymerization, preferably, the polymerization temperature is 0-150℃, preferably 40-100℃. The polymerization pressure of the first olefin is greater than or equal to atmospheric pressure, preferably 0.5-2.5 MPaG. The residence time is 0.5-5 h, preferably 1-2 h.

[0090] In this invention, the conditions for the olefin gas-phase polymerization reaction include: a temperature of 40-100℃, which can be any two values ​​from 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, 100℃ or above, preferably 60-80℃; a pressure of 0.6-1.4 MPaG, which can be any two values ​​from 0.6MPaG, 0.7MPaG, 0.75MPaG, 0.8MPaG, 0.9MPaG, 1MPaG, 1.1MPaG, 1.15MPaG, 1.2MPaG, 1.25MPaG, 1.3MPaG, 1.4MPaG or above, preferably 1-1.3MPaG; and a residence time of 0.1-2 h, preferably 0.2-1 h.

[0091] In this invention, the olefin gas-phase polymerization reaction is carried out directly after the first olefin polymerization reaction is completed. Preferably, the cooling and / or drying operation is not included between step (1) and step (2) in the method.

[0092] In this invention, step (2) further includes deactivating the product after reaction. Under preferred conditions, the deactivation treatment includes: degassing the product after reaction, introducing wet nitrogen gas formed by mixing nitrogen and steam, thereby removing the residual hydrocarbons in the product after reaction and deactivating the residual catalyst.

[0093] In this invention, step (3) involves mixing, melting, and extruding the product obtained in step (2) with composite nanopowder rubber nucleating agent C, optionally an antioxidant, and optionally a halogen absorber. The composite nanopowder rubber nucleating agent C, antioxidant, and halogen absorber are defined as described above and will not be repeated here.

[0094] In this invention, there are no particular limitations on the specific method and conditions of mixing, as long as the components are thoroughly and uniformly mixed. For example, the mixing can be carried out in a high-speed mixer, and the mixing process can be continuous or intermittent.

[0095] In this invention, the melt extrusion granulation can be carried out on conventional equipment in the art, such as a twin-screw extruder for melt extrusion, followed by granulation using a pelletizer.

[0096] A third aspect of the present invention provides a polyolefin resin composition obtained by the method described in the second aspect above.

[0097] In this invention, there is no particular limitation on the form of the polyolefin resin composition when it is used. It can be adapted to the actual application scenario. Preferably, before application, the polyolefin resin composition is further subjected to molding or blow molding. The molding method includes, but is not limited to, extrusion molding and injection molding.

[0098] A fourth aspect of the present invention provides a polyolefin resin article made from the polyolefin resin composition described in the first or third aspect above.

[0099] According to the present invention, preferably, the haze of the polyolefin resin product is greater than or equal to 80% when the thickness is 2 mm.

[0100] According to the present invention, preferably, the light transmittance of the polyolefin resin product when the thickness is 2 mm is greater than or equal to 70%.

[0101] In this invention, the haze and transmittance are obtained by measuring the injection-molded sample according to GB / T2410-2008, with a sample thickness of 2mm, which will not be elaborated further below.

[0102] The fifth aspect of the present invention provides the use of the polyolefin resin composition described in the first or third aspect above, or the polyolefin resin article described in the fourth aspect, in at least one of automobile bumpers, packaging boxes, and toys.

[0103] The present invention will be described in detail below through embodiments.

[0104] The testing methods for each parameter involved in the following examples and comparative examples are as described above.

[0105] Polyolefin resin products: Tensile strength (MPa): The prepared resin composition was granulated by screw extruder and injection molded to obtain a sample. The injection molded sample was measured in accordance with GB / T1040.1-2006.

[0106] Flexural modulus (MPa): The prepared resin composition was granulated by screw and injection molded to obtain a sample. The injection molded sample was measured according to GB / T9341-2008.

[0107] Notched impact strength of simply supported beam (kJ / m) 2 The prepared resin composition was granulated by screw extruder and injection molded to obtain a sample, which was then tested at 23℃ according to GB / T 1043.1-2008.

[0108] In the following examples and comparative examples, The polymerization reaction was carried out in a polypropylene pilot plant.

[0109] VP101B is a composite nanopowder rubber nucleating agent, purchased from Sinopec (Beijing) Chemical Research Institute Co., Ltd., and marketed under the trade name VP101B. VP101B contains 56 wt% cross-linked styrene-butadiene powder rubber, 20 wt% α-crystalline nucleating agent (sodium 2,4,8,10-tetratert-butyl=12H-dibenzo[d,g][1,3,2]dioxaphosphazenecyclooctadiene-6-acid salt 6-oxide), and 24 wt% sodium benzoate. VP101E is a composite nanopowder rubber nucleating agent, purchased from Sinopec (Beijing) Chemical Research Institute Co., Ltd., which includes 60% by weight of cross-linked styrene-butadiene powder rubber and 20% by weight of α crystal nucleating agent ((1R,2S)-rel-1,2-cyclohexanedicarboxylate calcium salt (1:1) type), and also contains 20% by weight of sodium benzoate; The main antioxidant is antioxidant 1010, chemically named pentaerythritol tetrakis[b-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid], commercially available; The auxiliary antioxidant is antioxidant 168, chemically named tris[2,4-di-tert-butylphenyl]phosphite, which is commercially available. The halogen absorbent is calcium stearate, which is commercially available.

[0110] The main catalyst Cat-1 was prepared according to the preparation method in Example B1 of CN117924562A.

[0111] Unless otherwise specified, all reagents used can be purchased commercially.

[0112] Example 1 The first olefin polymerization catalyst prepolymerization: The main catalyst Cat-1, the co-catalyst (triethylaluminum), and the external electron donor dicyclohexyldimethoxysilane (DCPMS) were mixed and pre-contacted at 10°C for 20 min. Then, the mixture was continuously added to the prepolymerization reactor for prepolymerization. The flow rates of triethylaluminum (TEAL) were 6 g / hr, DCPMS were 1.02 g / hr, and the main catalyst was 0.36 g / hr. Prepolymerization was carried out in a propylene liquid phase bulk environment at 15°C for approximately 4 min. The prepolymerization factor was measured to be 120 times. The prepolymerized olefin polymerization catalyst is continuously fed into the loop reactor, where the homopolymerization of propylene is completed. After the reaction, unreacted propylene is removed by flash evaporation. The loop polymerization reaction temperature is 70°C, the reaction pressure is 3.7 MPaG, and the molar ratio of hydrogen to propylene in the reactor is 0.0068.

[0113] After the reaction in the loop reactor, the material obtained from the homopolymerization reaction was injected into a fluidized bed gas-phase reactor for copolymerization of ethylene and propylene. The gas-phase reaction temperature was 78℃, the reaction pressure was 1.2 MPaG, the molar ratio of ethylene / (propylene + ethylene) was 0.17, and the molar ratio of hydrogen to ethylene in the circulating gas of the gas-phase reactor was 0.69 as determined by online chromatography. After degassing and wet nitrogen deactivation treatment, the product obtained from the reaction was blended with 0.25 wt% of composite nanopowder rubber nucleating agent VP101B, 0.2 wt% of antioxidant B225 (168:1010=1:1 (g / g)), and 0.055 wt% of calcium stearate. The blended product was granulated using a twin-screw extruder to obtain the polyolefin resin composition, the composition parameters of which are shown in Table 1. The granulated polyolefin resin composition was injection molded, and the properties of the resulting polyolefin resin product Z1 were measured. The test results are shown in Table 2.

[0114] Example 2 The method is the same as in Example 1, except that the molar ratio of hydrogen to propylene in the loop reactor is 0.0045; the molar ratio of ethylene to (propylene + ethylene) in the gas phase reactor is 0.11; the molar ratio of hydrogen to ethylene is 0.47; the composition parameters of the polyolefin resin composition are shown in Table 1; and the properties of the injection-molded polyolefin resin product Z2 are shown in Table 2.

[0115] Example 3 The method is the same as in Example 1, except that the molar ratio of hydrogen to propylene in the loop reactor is 0.0057; the molar ratio of ethylene / (propylene + ethylene) in the gas phase reactor is 0.15, and the molar ratio of hydrogen to ethylene is 0.65. The composition parameters of the polyolefin resin composition are shown in Table 1, and the properties of the injection-molded polyolefin resin product Z3 are shown in Table 2.

[0116] Example 4 The method is the same as in Example 1, except that the molar ratio of hydrogen to propylene in the loop reactor is 0.0077; the molar ratio of ethylene to (propylene + ethylene) in the gas phase reactor is 0.16, and the molar ratio of hydrogen to ethylene is 0.55; and the nucleating agent is VP101E. The compositional parameters of the polyolefin resin composition are shown in Table 1, and the properties of the injection-molded polyolefin resin product Z4 are shown in Table 2.

[0117] Example 5 The method is the same as in Example 1, except that the molar ratio of hydrogen to propylene in the loop reactor is 0.0061; the molar ratio of ethylene to (propylene + ethylene) in the gas phase reactor is 0.12, the molar ratio of hydrogen to ethylene is 0.50; and the nucleating agent is VP101E.

[0118] The composition parameters of the polyolefin resin composition are shown in Table 1, and the properties of the injection-molded polyolefin resin product Z5 are shown in Table 2.

[0119] Example 6 The method is the same as in Example 1, except that the molar ratio of hydrogen to propylene in the loop reactor is 0.0035.

[0120] The composition parameters of the polyolefin resin composition are shown in Table 1, and the properties of the injection-molded polyolefin resin product Z5 are shown in Table 2.

[0121] Comparative Example 1 The method is the same as in Example 1, except that the molar ratio of hydrogen to propylene in the loop reactor is 0.0062; the molar ratio of ethylene to (propylene + ethylene) in the gas phase reactor is 0.16; the molar ratio of the second hydrogen to ethylene is 0.60; and the nucleating agent is transparent nucleating agent NA-21 (aryl phosphate salt nucleating agent), a product of ADEKA Corporation of Japan, added at a rate of 0.1 wt%.

[0122] The composition parameters of the polyolefin resin composition DS1 are shown in Table 1, and the properties of the injection-molded polyolefin resin product DZ1 are shown in Table 2.

[0123] Comparative Example 2 The method is the same as in Example 1, except that the molar ratio of hydrogen to propylene in the loop reactor is 0.0092; the molar ratio of ethylene to (propylene + ethylene) in the gas phase reactor is 0.36, and the molar ratio of hydrogen to ethylene is 0.035.

[0124] The compositional parameters of the polyolefin resin composition are shown in Table 1, and the properties of the injection-molded polyolefin resin product DZ2 are shown in Table 2.

[0125] Comparative Example 3 The method was followed in Example 1, except that the main catalyst was replaced with commercial catalyst DQC-602, purchased from Beijing Aoda Branch of Sinopec Catalyst Co., Ltd. The molar ratio of hydrogen to propylene in the loop reactor was 0.0063; the molar ratio of ethylene to (propylene + ethylene) in the gas-phase reactor was 0.16, and the molar ratio of the second hydrogen to ethylene was 0.60.

[0126] The composition parameters of the polyolefin resin composition are shown in Table 1, and the properties of the injection-molded polyolefin resin product DZ3 are shown in Table 2.

[0127] Comparative Example 4 The method of Example 1 was followed, except that the composite nanopowder rubber nucleating agent C was not added. The composition parameters of the polyolefin resin composition are shown in Table 1, and the properties of the injection-molded polyolefin resin product DZ4 are shown in Table 2.

[0128] Table 1

[0129] Table 1 (continued)

[0130] Table 2

[0131] As can be seen from Tables 1 and 2, the polyolefin resin products obtained by the present invention have both high haze and high light transmittance.

[0132] In Comparative Example 1, the nucleating agent was replaced with the conventional commercial nucleating agent NA-21. Although the light transmittance of the polyolefin resin product was improved, its haze was only 51.3%, which is relatively low.

[0133] Compared with Example 1, the ethylene content in component B of Comparative Example 2 is not within the range defined by this invention, and the light transmittance of the polyolefin resin product is much lower.

[0134] Compared with Example 1, the main catalyst type of Comparative Example 3 was changed, and its main catalyst contained only one internal electron donor, specifically diisobutyl phthalate. The isotacticity of the resulting homopolymer polypropylene component decreased and the molecular weight distribution narrowed, resulting in a significant decrease in its flexural modulus and low light transmittance.

[0135] Compared with Example 1, no nucleating agent was added in Comparative Example 4, and the resulting polyolefin resin product had low haze.

[0136] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A polyolefin resin composition, characterized in that, The polyolefin resin composition contains polypropylene resin and a composite nanopowder rubber nucleating agent; Wherein, the polypropylene resin contains: (1) 75-90 parts by weight of homopolymer polypropylene A, which has an isotactic five-unit component fraction ≥96%, a molecular weight distribution Mw / Mn ≥9.5, and a rheological distribution index PI ≥6.5; (2) 10-25% by weight of ethylene-propylene elastic copolymer B, with the content of ethylene structural units being 15-35% by weight based on the total weight of ethylene-propylene elastic copolymer B. Based on 100 parts by weight of polypropylene resin, the content of composite nanopowder rubber nucleating agent C is 0.1-0.8% by weight. Based on the total weight of the composite nanopowder rubber nucleating agent C, it contains 10-99% by weight of nanopowder rubber and 1-90% by weight of nucleating agent.

2. The polyolefin resin composition according to claim 1, wherein, The polypropylene resin contains: (1) 75-85 parts by weight of homopolymer polypropylene A, with a fraction of isotactic five-unit components ≥97%, molecular weight distribution Mw / Mn ≥10, and rheological distribution index PI ≥7. (2) 15-25% by weight of ethylene-propylene elastic copolymer B, with the content of ethylene structural units being 20-30% by weight based on the total weight of ethylene-propylene elastic copolymer B. Preferably, based on 100 parts by weight of polypropylene resin, the content of composite nanopowder rubber nucleating agent C is 0.15-0.

5. Preferably, based on the total weight of the composite nanopowder rubber nucleating agent C, it contains 20-90% by weight of nanopowder rubber and 10-80% by weight of nucleating agent.

3. The polyolefin resin composition according to claim 1 or 2, wherein, The nanopowder rubber is selected from vulcanized powder rubber and / or non-vulcanized powder rubber; Preferably, the vulcanized powder rubber is selected from at least one of vulcanized natural rubber, vulcanized styrene-butadiene rubber, vulcanized nitrile rubber, vulcanized chloroprene rubber, vulcanized polybutadiene rubber, vulcanized polyacrylate rubber, vulcanized styrene-butadiene pyridine rubber, vulcanized isoprene rubber, vulcanized ethylene propylene rubber, and vulcanized polyurethane rubber, and is preferably vulcanized styrene-butadiene rubber. Preferably, the non-vulcanized powdered rubber is selected from at least one of cross-linked styrene-butadiene powdered rubber, cross-linked polybutadiene powdered rubber, cross-linked chloroprene powdered rubber, and cross-linked acrylate powdered rubber, and is preferably cross-linked styrene-butadiene powdered rubber; Preferably, the nucleating agent is an α-crystal nucleating agent and / or a β-crystal nucleating agent; Preferably, the α-crystal nucleating agent is an aryl phosphate nucleating agent, preferably selected from at least one of sodium 2,2'-methylene-bis(4,6-di-tert-butylphenyl)phosphate, hydroxy-bis[2,2'-ethimide-bis(4,6-di-tert-butylphenyl)phosphate] and hydroxy-bis[2,4,8,10-tetra(1,1'-dimethylethyl)-6-hydroxy-12H-dibenzo[d,g]dioxophosphatacyclo-6-oxo]aluminum and sodium 2,4,8,10-tetra-tert-butyl-12H-dibenzo[d,g][1,3,2]dioxaphosphatacyclooctadiene-6-acid 6-oxide; Preferably, the β-crystal nucleating agent is selected from at least one of polycyclic aromatic hydrocarbon β-crystal nucleating agents, organic acid β-crystal nucleating agents, organic salt β-crystal nucleating agents, amide β-crystal nucleating agents, rare earth β-crystal nucleating agents, and inorganic salt β-crystal nucleating agents, and is more preferably an amide β-crystal nucleating agent and / or a rare earth β-crystal nucleating agent.

4. The polyolefin resin composition according to any one of claims 1-3, wherein, The melt flow rate of the polyolefin resin composition under a load of 2.16 kg at 230 °C is 30-80 g / 10 min. Preferably, the total content of ethylene structural units is 3-8% by weight, based on the total weight of the polyolefin resin composition.

5. The polyolefin resin composition according to any one of claims 1-4, wherein, The polyolefin resin composition further contains xylene-soluble substances, wherein the content of the xylene-soluble substances is 10-25% by weight. Preferably, the intrinsic viscosity of the xylene-soluble component in the polyolefin resin composition is 1-1.5 dL / g; Preferably, the intrinsic viscosity of the polyolefin resin composition is 1.3-2 dL / g.

6. The polyolefin resin composition according to any one of claims 1-5, wherein the polyolefin resin composition further comprises an antioxidant and / or a halogen absorber; Preferably, based on 100 parts by weight of polypropylene resin, the antioxidant content is 0.05-0.5% by weight, and the halogen absorbent content is 0.02-0.1% by weight. Preferably, the antioxidant is a hindered phenolic antioxidant and / or a phosphite antioxidant; Preferably, the halogen absorbent is calcium stearate and / or hydrated talc.

7. A method for preparing a polyolefin resin composition, characterized in that, The method includes: (1) Under the first olefin polymerization conditions, propylene monomer is contacted with Ziegler-Natta catalyst with high stereoselectivity, and unreacted monomer is removed from the mixture obtained after the contact reaction to obtain homopolymer polypropylene A. (2) Under the conditions of olefin gas-phase polymerization, ethylene monomer and propylene monomer are contacted and reacted with homopolymer polypropylene A obtained in step (1), and unreacted monomers are removed from the mixture obtained after the contact reaction to obtain a mixture containing homopolymer polypropylene A and ethylene-propylene elastic copolymer B. (3) The product obtained in step (2) is mixed with composite nanopowder rubber nucleating agent C, optionally antioxidant, optionally halogen absorber, melted and extruded into granules; In step (1), the molar ratio of hydrogen to propylene is 0.001-0.01:1; Based on the total weight of 100 parts by weight of homopolymer polypropylene A and ethylene-propylene elastic copolymer B, the amount of composite nanopowder rubber nucleating agent C is 0.1-0.8% by weight. Based on the total weight of the composite nanopowder rubber nucleating agent C, it contains 10-99% by weight of nanopowder rubber and 1-90% by weight of nucleating agent.

8. The method according to claim 7, wherein, The highly stereoselective Ziegler-Natta catalyst comprises: (i) a main catalyst containing a product obtained by reacting a magnesium source, a titanium source, and an internal electron donor; the internal electron donor comprising phosphate esters and / or α-cyanosuccinate; (ii) a co-catalyst; and (iii) an optional external electron donor; Preferably, the co-catalyst is an organoaluminum compound, more preferably an alkylaluminum compound, and more preferably selected from at least one of triethylaluminum, tripropylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-n-octylaluminum, diethylaluminum hydrogen, diisobutylaluminum hydrogen, diethylaluminum chloride, diisobutylaluminum chloride, sesquiethylaluminum chloride, and diethylaluminum chloride, and more preferably trialkylaluminum, and more preferably selected from at least one of triethylaluminum, tri-n-butylaluminum, and triisobutylaluminum; Preferably, the external electron donor is an organosilicon compound, preferably selected from at least one of cyclohexylmethyldimethoxysilane, diisopropyldimethoxysilane, di-n-butyldimethoxysilane, diisobutyldimethoxysilane, diphenyldimethoxysilane, methyl tert-butyldimethoxysilane, dicyclopentyldimethoxysilane, 2-ethylpiperidinyl-2-tert-butyldimethoxysilane, (1,1,1-trifluoro-2-propyl)-2-ethylpiperidinyldimethoxysilane, and (1,1,1-trifluoro-2-propyl)-methyldimethoxysilane. Preferably, the molar ratio of the main catalyst to the co-catalyst is 1:12-720, more preferably 1:25-500; the main catalyst is calculated as titanium, and the co-catalyst is calculated as aluminum; Preferably, the molar ratio of the main catalyst to the external electron donor is 1:1-120, more preferably 1:10-100; the main catalyst component is calculated as titanium, and the external electron donor is calculated as silicon.

9. The method according to claim 7 or 8, wherein, The conditions for the first olefin polymerization reaction include: a temperature of 0-150℃, preferably 40-100℃; and a residence time of 0.5-5h, preferably 1-2h. Preferably, the conditions for the olefin gas-phase polymerization reaction include: a temperature of 40-100℃, preferably 60-80℃; a pressure of 0.6-1.4 MPaG, preferably 1-1.3 MPaG; and a residence time of 0.1-2 h, preferably 0.2-1 h. Preferably, the method does not include cooling and / or drying operations between steps (1) and (2).

10. A polyolefin resin composition obtained by the method according to any one of claims 7-9.

11. A polyolefin resin article made from the polyolefin resin composition of claims 1-6 or 10.

12. The polyolefin resin article according to claim 11, wherein, The haze of the polyolefin resin product with a thickness of 2 mm is greater than or equal to 80%. Preferably, the light transmittance of the polyolefin resin product is greater than or equal to 70% when the thickness is 2 mm.

13. Use of the polyolefin resin composition of claims 1-6 or 10 or the polyolefin resin article of claim 11 or 12 in at least one of automobile bumpers, packaging boxes and toys.

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