A rigid-tough balance polypropylene composition and a preparation method thereof

Abstract

This invention belongs to the field of polypropylene technology, specifically relating to a rigid-toughness balanced polypropylene composition and its preparation method. The rigid-toughness balanced polypropylene composition comprises a first propylene polymer component and a second propylene polymer component; the first propylene polymer component contains 0.03-5.00 wt% of a weight-average molecular weight M. W Ultra-high molecular weight polypropylene with a molecular weight of ≥10,000,000; number average molecular weight M of ultra-high molecular weight polypropylene components. n Peak molecular weight M of propylene polymer p The ratio is ≥10; based on 100 parts by weight of the total weight of the rigid-toughness balanced polypropylene composition, the content of the first propylene polymer component is 5-25 parts by weight, and the content of the second propylene polymer component is 75-95 parts by weight; the rigid-toughness balanced polypropylene composition prepared by the present invention has both high rigidity and toughness.

Description

Technical Field

[0001] This invention belongs to the field of polypropylene technology, specifically relating to a rigid-toughness balanced polypropylene composition and its preparation method. Background Technology

[0002] Polypropylene (PP) is a high-performance thermoplastic synthetic resin, one of the five major general-purpose plastics. It boasts advantages such as low density, non-toxicity, ease of processing, high strength, good chemical stability, and excellent electrical insulation. It also possesses the best heat resistance among general-purpose resins. While PP exhibits significantly better rigidity, heat resistance, tensile modulus, and compressive hardness than polyethylene (PE), its relatively low impact strength and poor toughness limit its engineering applications. A balanced rigidity and toughness in PP has become a hot topic in the development of high-performance, high-value-added PP products in recent years, significantly expanding its application range in important sectors such as automobiles and home appliances. Furthermore, its excellent flowability gives it superior processing performance, significantly shortening processing time, improving production efficiency, and reducing enterprise production costs. Higher melt flowability is also an important development trend for high-performance PP.

[0003] However, with consumption upgrades and technological advancements, the market has placed more stringent integrated demands on the performance of packaging materials. Especially in high-end packaging scenarios that require withstanding certain temperatures, pressures, or internal stresses, mere transparency or toughness is no longer sufficient. These applications require materials to possess an excellent balance of comprehensive performance. Existing technologies often improve the stiffness-toughness balance of materials by adding inorganic particles and toughening agents, or by blending block copolymers with nanocomposite nucleating agents, or by blending several types of polypropylene with polyethylene.

[0004] Chinese patent CN102311583B discloses a rigid-toughness balanced polypropylene, which is made from the following raw materials by weight percentage: 45%-90% polypropylene, 5%-20% coupling agent modified low-mesh talc, 5%-30% high-mesh talc, 0%-15% toughening agent, 0%-2% antioxidant, and 0-2% other additives. This invention improves the rigidity-toughness balance of the material by modifying inorganic particles and toughening agents. However, if the content of inorganic particles and toughening agents is too high, it will affect the flowability of the material. At the same time, if the ash content is too high, the application fields will be limited.

[0005] Chinese patent CN103571123B discloses an impact-resistant polypropylene composition for automobile bumpers and its preparation method, comprising the following components: 100 parts of block copolymer polypropylene, 0.15-0.3 parts of processing aid, 0.15-0.3 parts of nanocomposite nucleating agent, and 0.15-0.3 parts of peroxide masterbatch. This invention prepares impact-resistant polypropylene material by blending block copolymer polypropylene, nanocomposite nucleating agent, peroxide masterbatch, and processing aid. However, it has low flexural modulus, poor rigidity, and limited application areas.

[0006] Chinese patent CN103923381B discloses a high-modulus, ultra-high-impact polypropylene composite material and its preparation method, composed of the following raw materials by weight percentage: polypropylene 40-74%, ultrafine inorganic filler 10-30%, elastomer toughening agent 15-30%, stabilizer 0.1-2%, and other additives 0-5%. This invention improves the stiffness-toughness balance of the material through ultrafine inorganic filler and elastomer toughening agent. However, excessively high contents of inorganic particles and toughening agents affect the material's flowability, and excessively high ash content limits its application areas.

[0007] Chinese patent CN104558822B discloses a polypropylene composition comprising impact-resistant polypropylene, random copolymer polypropylene, and ethylene homopolymer. The impact-resistant polypropylene comprises 70-90 parts by weight, the random copolymer polypropylene comprises 4-20 parts by weight, and the ethylene homopolymer comprises 4-20 parts by weight. This invention improves the stiffness-toughness balance of the material through blending impact-resistant polypropylene, random copolymer polypropylene, and ethylene homopolymer. However, it suffers from low flexural modulus and poor rigidity, and the material also has low melt flowability, limiting its application areas.

[0008] Current technologies primarily improve the stiffness-toughness balance of materials through inorganic particles and toughening agents. However, excessively high contents of inorganic particles and toughening agents affect the material's flowability, while excessively high ash content limits its application in many fields with strict requirements for flowability and ash content. Although blending block copolymers with nanocomposite nucleating agents or with polyethylene can improve the stiffness-toughness balance to some extent, the flexural modulus is difficult to achieve ideal levels, resulting in insufficient rigidity. Furthermore, the material's melt flowability is low, failing to meet the requirements of applications demanding both high rigidity and flowability. Innovative technologies are urgently needed to address these issues. Summary of the Invention

[0009] The purpose of this invention is to provide a rigid-toughness balanced polypropylene composition and its preparation method.

[0010] To achieve the above objectives, the present invention provides the following technical solution:

[0011] A rigid-toughness balanced polypropylene composition, the composition comprising a first propylene polymer component and a second propylene polymer component; The first propylene polymer component contains a weight-average molecular weight M W Ultra-high molecular weight polypropylene components with a molecular weight of ≥10,000,000; The content of the ultra-high molecular weight polypropylene component is 0.03-5.00 wt% (e.g., 0.035 wt%, 0.04 wt%, 0.05 wt%, 0.06 wt%, 0.08 wt%, 0.1 wt%, 0.2 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.8 wt%, 1.0 wt%, 1.5 wt%, 1.8 wt%, 2.0 wt%, 2.5 wt%, 3.0 wt%, 3.5 wt%, 4.0 wt%, 4.5 wt%), preferably 0.05-2.00 wt%. The ratio of the number-average molecular weight Mn of the ultra-high molecular weight polypropylene component to the peak molecular weight Mp of the propylene polymer is Mn(M W ≥10,000,000) / Mp≥10, for example, 12, 14, 15, 16, 18, 19, 20, 22, 24, 25, 26, 28, 30, 32, 34, 35, 36, 40, 45, 48, 50, 55, 58, 60, 65, 68, 70, 72, 74, 75, preferably ≥30.

[0012] Based on 100 parts by weight of the total weight of the rigid-toughness balanced polypropylene composition, the content of each component in the polypropylene composition is as follows: the amount of the first propylene polymer component is 5-25 parts by weight; preferably 10-25 parts by weight; the amount of the second propylene polymer is 75-95 parts by weight, preferably 80-95 parts by weight.

[0013] The second propylene polymer component is selected from impact-resistant polypropylene and / or random copolymer polypropylene; preferably, the second propylene polymer component is impact-resistant polypropylene.

[0014] The impact-resistant polypropylene has a melt flow index of 20-100 g / 10min at 230°C and a load of 2.16 kg, for example, 21 g / 10min, 23 g / 10min, 25 g / 10min, 28 g / 10min, 30 g / 10min, 32 g / 10min, 35 g / 10min, 40 g / 10min, 43 g / 10min, 48 g / 10min, 51 g / 10min, 55 g / 10min, 60 g / 10min, 62 g / 10min, 68 g / 10min, 70 g / 10min, 75 g / 10min, etc. 0g / 10min, 80g / 10min, 81g / 10min, 82g / 10min, 90g / 10min, 95g / 10min, 100g / 10min, with an ethylene mass percentage content of 7%-30%, for example, ethylene mass percentage content of 7%, 8%, 9%, 10%, 11%, 13%, 15%, 17%, 19%, 20%, 22%, 25%, 28%, 30%; preferably, the impact-resistant polypropylene has a melt index of 20-70g / 10min at 230℃ and a load of 2.16kg, and an ethylene mass percentage content of 7%-25%.

[0015] The weight ratio of the first propylene polymer component to the second propylene polymer component is (0.05-0.33):1, for example, the weight ratio of the first propylene polymer component to the second propylene polymer component is 0.05:1, 0.07:1, 0.10:1, 0.12:1, 0.15:1, 0.18:1, 0.20:1, 0.23:1, 0.28:1, 0.32:1, 0.33:1; preferably (0.08-0.28):1.

[0016] The method for preparing the propylene polymer employs two or more polymerization reaction stages arranged in a sequential manner; the method includes the following steps: (i) In the presence of a polymerization catalyst and hydrogen, propylene undergoes a first-stage polymerization reaction for 0.1-10 hours to prepare a feed stream containing polypropylene-I component; (ii) After the first stage of polymerization, a hydrogenation catalyst is introduced into the system, and the polymerization reaction continues for 0.01-3 hours to obtain the weight-average molecular weight M. W ≥10,000,000 ultra-high molecular weight polypropylene (UHMWPP) components; The reaction was then stopped to obtain the propylene polymer containing ultra-high molecular weight polypropylene (UHMWPP) components; The molar ratio of the hydrogenation catalyst to the total amount of hydrogen in the polymerization system is 1 / 10000-1 / 100, for example, 1 / 8000, 1 / 6000, 1 / 5000, 1 / 4000, 1 / 2000, 1 / 1000, 1 / 800, 1 / 600, 1 / 500, 1 / 400, 1 / 200, 1 / 150, preferably 1 / 10000-1 / 1000; The hydrogenation catalyst is a mixture of organometallic compounds and alkylaluminum compounds; Preferably, in the mixture, the molar ratio of aluminum in the alkylaluminum compound to the organometallic compound ranges from 5.5 to 10.0:1, for example, 6:1, 6.5:1, 7:1, 8:1, 9:1, 9.5:1, and more preferably 5.5 to 8.0:1; Preferably, the organometallic compound has the general formula R(R')-MX(X'), wherein: R and R' are each independently cyclopentadienyl, indene, or fluorenyl without or with substituents, wherein the substituents are preferably selected from methyl, ethyl, propyl, butyl, or cycloalkyl. M is a transition metal element, preferably selected from one or more of Fe, Ti, Zr, Cr and Mn; X and X' are each independently a halogen atom, an alkyl group, or an alkoxy group.

[0017] In some embodiments, the organometallic compound is selected from one or more of bis(cyclopentadienyl)titanium chloride, bis(cyclopentadienyl)titanium dibromide, bis(cyclopentadienyl)methoxytitanium chloride, bis(cyclopentadienyl)ethoxytitanium chloride, bis(cyclopentadienyl)phenoxytitanium chloride, bis(cyclopentadienyl)dimethyltitanium, bis(cyclopentadienyl)diethyltitanium, diindyltitanium chloride, diindyldibromide, diindyldimethyltitanium, diindyldiethyltitanium, bis(cyclopentadienyl)zirconia, bis(cyclopentadienyl)zirconia, bis(cyclopentadienyl)dimethylzirconia, and bis(cyclopentadienyl)diethylzirconia, preferably selected from one or both of bis(cyclopentadienyl)titanium chloride and bis(cyclopentadienyl)diethyltitanium.

[0018] In some embodiments, the alkylaluminum compound is selected from one or more of trimethylaluminum, triethylaluminum, tributylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, tridecylaluminum, dimethylaluminum chloride, diethylaluminum chloride, dibutylaluminum chloride, diisobutylaluminum chloride, methylaluminoxane (MAO) and modified methylaluminoxane (MMAO), preferably selected from triethylaluminum and / or methylaluminoxane.

[0019] In some embodiments, the hydrogenation catalyst is a mixture of Cp2TiCl2 and an alkylaluminum compound; wherein the molar ratio of aluminum in the alkylaluminum compound to Cp2TiCl2 ranges from 5.5 to 10.0:1, preferably from 5.5 to 8.0:1.

[0020] In the method for preparing the propylene polymer, the polymerization catalyst used includes, but is not limited to, Ziegler-Natta type catalysts, which typically include: (a) an active solid catalyst component, preferably a titanium-containing solid catalyst active component; (b) an organoaluminum compound as a co-catalyst component; and optionally, (c) an external electron donor component.

[0021] The ratio of the active solid catalyst component to the organoaluminum compound can be expressed as Ti / Al molar ratio, and is 1:5 to 1:400 (e.g., 1:10, 1:50, 1:120, 1:200, 1:300), preferably 1:25 to 1:100.

[0022] Available active solid catalyst components (active main catalyst components) include commercially available SUG catalysts, SAL catalysts, or other catalysts containing both titanium chloride and magnesium chloride.

[0023] The organoaluminum compound used as a cocatalyst component is preferably an alkylaluminum compound, more preferably a trialkylaluminum compound, such as triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, methylaluminoxane (MAO), modified methylaluminoxane (MMAO), etc.

[0024] The compound serving as the external electron donor component can be a variety of electron-donating compounds, including but not limited to alkoxy-substituted silanes; for example, those with the general formula SiR n (OR') 4-n In the formula: 0≤n≤2, R and R' may be the same or different, and are independently selected from alkyl, cycloalkyl, aryl, haloalkyl, nitrogen-containing groups, etc. R can also be a halogen or a hydrogen atom; specifically, it may include, but is not limited to, tetramethoxysilane, tetraethoxysilane (TEOS), dimethyldimethoxysilane, dimethyldiethoxysilane, methyl tert-butyldimethoxysilane, methyl isopropyldimethoxysilane, diphenoxydimethoxysilane, vinyltrimethoxysilane, methylcyclohexyldimethoxysilane, ethylcyclohexyldimethoxysilane, di-n-propyldimethoxysilane, diisopropyldimethoxysilane, di-n-butyldimethoxysilane, and diisobutyldimethoxysilane. Alkane, di-tert-butyldimethoxysilane, dicyclopentyldimethoxysilane (D-donor), cyclopentyltrimethoxysilane, isopropyltrimethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, ethyltriethoxysilane, diethylaminotriethoxysilane, cyclohexylpyrrolidinedimethoxysilane, bis(pyrrolidine)-dimethoxysilane, bis(perhydroisoquinoline)dimethoxysilane, 2-ethylpiperidinyl-2-tert-butyldimethoxysilane, (1,1,1-trifluoro-2-propyl)-2-ethylpiperidinyldimethoxysilane, and (1,1,1-trifluoro-2-propyl)-methyldimethoxysilane, etc. Preferred are dicyclopentyldimethoxysilane (D-donor), methylcyclohexyldimethoxysilane, diisopropyldimethoxysilane, diisobutyldimethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, tetraethoxysilane (TEOS), and diethylaminotriethoxysilane.

[0025] The amount of the external electron donor component in the polymerization catalyst can be selected in accordance with conventional methods in the art, and will not be elaborated here.

[0026] In the method for preparing the propylene polymer, the polymerization reaction is carried out in two stages in a single reactor. In the first stage, propylene polymerization is carried out under normal hydrogen concentration to generate a low molecular weight propylene polymer-I component. Then, a small amount of hydrogenation catalyst is added to the single reactor to remove residual hydrogen. In the second stage, the polymerization reaction continues under near-hydrogen-free conditions in the single reactor, thereby generating a certain amount of ultra-high molecular weight polypropylene component (UHMWPP) in the system, ultimately obtaining a propylene polymer product containing ultra-high molecular weight polypropylene component (UHMWPP). This preparation method does not require a system consisting of multiple reactors and complex reaction condition control, does not require the use of complex matching of different external electron donors, does not require the use of large amounts of hydrogen, and does not require the use of large amounts of hydrogenation catalyst. It can prepare polypropylene resin with specific structure and characteristics simply by directly adding a hydrogenation catalyst to the single reactor after the polymerization reaction is completed and controlling its amount within an appropriate range to continue polymerization.

[0027] The aforementioned rigid-toughness balanced polypropylene composition further includes antioxidants, nucleating agents, acid removers, light stabilizers, and other additives. The total amount of these additives is 0.5%-2%; for example, 0.5%, 1%, or 2%, preferably 0.5%-1%.

[0028] The method for preparing rigid-toughness balanced polypropylene, wherein the rigid-toughness balanced polypropylene can be prepared by blending two components.

[0029] The method for preparing rigid-toughness balanced polypropylene, wherein the blending method can be solution blending or screw extrusion melt blending.

[0030] The solution blending method includes the following steps: simultaneously placing the first propylene polymer component and the second propylene polymer component into a good solvent of polyolefin for heating and dissolving; after the polymer is uniformly dissolved, placing the polymer solution into a poor solvent of polymer and stirring to settle; separating the precipitate from the poor solvent of polyolefin for solid-liquid separation; mixing the separated polymer with the additives; and placing the mixed precipitate into a vacuum oven for drying.

[0031] The solution blending method: wherein the good solvent for the polyolefin is: petroleum ether, toluene, dichloromethane, chloroform, tetrahydrofuran, xylene, cyclohexane, trichlorobenzene, etc., preferably petroleum ether, xylene, and toluene; The dissolution temperature of the polyolefin with the good solvent is 100-200℃, for example, 100℃, 150℃, 200℃, and the dissolution time of the polyolefin with the good solvent is 30min-90min, for example, 30min, 40min, 50min, 60min, 70min, 80min, 90min.

[0032] The unsuitable solvents for the polyolefin are acetone, ethanol, ethyl acetate, methanol, butyl acetate, isopropanol, n-butanol, etc., with acetone, ethanol, and methanol being preferred.

[0033] The screw extrusion melt blending method includes the following steps: The first propylene polymer component, the second propylene polymer component, and the additives are mixed, and the resulting mixture is melt-extruded and granulated to obtain the melt-reinforced polypropylene composition.

[0034] The melt extrusion is carried out in a twin-screw extruder; Preferably, the twin-screw extruder has a screw length-to-diameter ratio of 10-100, for example, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, or 100, and an extrusion temperature of 110-220℃, for example, 110℃, 120℃, 130℃, 135℃, 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, or 220℃. This invention, through the synergistic effect of a first propylene polymer component and a second propylene polymer component in a specific ratio, reduces the ash content of the material from the source without the need for inorganic fillers or additional toughening agents. The weight-average molecular weight M in the first propylene polymer component... W Ultra-high molecular weight polypropylene with a molecular weight of ≥10,000,000, through its unique macromolecular chain structure, forms physical cross-linking points and a well-compatible network with the second propylene polymer component. While ensuring the basic stability of melt flowability, it simultaneously improves the rigidity (flexural modulus) and toughness (impact strength) of the material, effectively solving the technical bottleneck of traditional polypropylene where rigidity and toughness cannot be achieved simultaneously.

[0035] Especially when ultra-high molecular weight polypropylene meets the number average molecular weight Mn(M W When the ratio of the molecular weight (≥10,000,000) to the peak molecular weight (Mp) is ≥10, the entanglement effect of the macromolecular chains is better, further enhancing the performance balance. The specific addition of the two polypropylene molecules balances processing convenience and product performance, significantly shortening the processing cycle and reducing production costs, thus possessing outstanding economic value and market competitiveness.

[0036] This invention, through precise selection and parameter optimization of the second propylene polymer component, achieves a highly efficient synergistic effect with the first propylene polymer component, significantly improving the overall performance of the composition. The impact-resistant polypropylene, with its inherent elastomeric phase, initially imparts basic toughness to the material, forming a synergistic system of rigidity enhancement and toughness complementarity with the ultra-high molecular weight polypropylene in the first component: the macromolecular chains of the ultra-high molecular weight polypropylene form physical cross-linking points, strengthening the material's rigid framework, while the impact-resistant polypropylene disperses stress through its elastomeric phase. This synergistic effect avoids the performance limitations of a single component.

[0037] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: 1. This invention abandons the traditional improvement paths in existing technologies, such as relying on inorganic particles + toughening agents, blending block copolymers with nanocomposite nucleating agents, and blending various types of polypropylene with polyethylene. Instead, it innovatively adopts a technical solution of blending special-structure polypropylene with impact-resistant polypropylene to achieve highly efficient optimization of the material's rigidity and toughness balance. This special-structure polypropylene and impact-resistant polypropylene form a synergistic effect, eliminating the need for additional inorganic fillers or toughening agents. This avoids the problems of decreased fluidity and excessive ash content caused by excessive inorganic particle and toughening agent content in traditional solutions, while also solving some of the pain points of insufficient rigidity and poor melt fluidity in existing technologies. It simultaneously improves the rigidity and toughness of the material while ensuring processing performance.

[0038] 2. The polypropylene composition of this invention achieves a three-dimensional balance breakthrough in "melt flowability-rigidity-toughness" through the precise synergy between the first and second propylene polymer components. The ultra-high molecular weight polypropylene in the first component forms a physical cross-linking network with unique macromolecular chain entanglement, providing rigid support for the material. The second component, with its optimized melt index and ethylene content, ensures compatibility with the first component while also dispersing stress through its own elastomeric phase. Together, they form a synergistic system of "rigidity enhancement-toughness buffering." This synergistic effect completely solves the pain points of traditional technologies where "rigidity and toughness cannot be simultaneously achieved" and "flowability and performance are contradictory." It eliminates the need for inorganic particles or additional toughening agents, reduces ash content, and broadens applications in fields with stringent comprehensive performance requirements, such as precision automotive parts and high-end home appliances, combining technological innovation with practical value. Detailed Implementation

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Unless otherwise specified in the examples, the conditions should be performed under standard conditions or conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the examples are assumed to be commercially available.

[0041] <Source of Raw Materials> The first propylene polymer component (PP1 and PP2) contains ultra-high molecular weight components. Catalyst A used in the preparation process was prepared according to Example 5 described in patent application CN101054424A, and the Ti content in catalyst A was 3.0 wt%.

[0042] The preparation steps of the hydrogenation catalyst used in the preparation of the first propylene polymer components PP1 and PP2 are as follows: Under a nitrogen atmosphere, dichlorodicyclopentadiene and triethylaluminum (triethylaluminum exists in the form of a 1.0 mol / L n-hexane solution) are mixed at a certain molar ratio at room temperature for at least 24 hours to prepare a mixture, which is the dichlorodicyclopentadiene hydrogenation catalyst; then 1.0 ml of the mixture is taken and diluted with 33 ml of n-hexane before use.

[0043] The polymerization reaction of the first propylene polymer component PP1 was carried out in a 5L stainless steel polymerization reactor, and the specific steps are as follows: (i) First, purge the reactor with purified nitrogen (water <1ppm, oxygen <1ppm); then add 2.2L of liquid propylene and 0.125mol of hydrogen sequentially at room temperature, and heat the system to 70°C; Before the reactor temperature reaches 70°C, 2.0 ml of 0.5 M triethylaluminum heptane solution, 0.4 ml of 0.5 M D-donor hexane solution and 8.1 mg of catalyst A prepared above are mixed for 5 minutes to obtain a mixture. When the reactor reaches 70°C, the mixture is injected into the reactor through the catalyst feed pipe and the reaction time is started to carry out the polymerization reaction, generating a material stream containing polypropylene component I. (ii) After the reaction has proceeded for 60 minutes, add 25.5 ml (concentration of 4.9 × 10⁻⁶) of the catalyst into the reactor through the catalyst feed pipe. -6 The hydrogenation catalyst (titanium dichlorodi ... Then, vent the unreacted material, cool down, and stop the reaction; (iii) The obtained polypropylene product was vacuum dried at 30°C for 2 hours, and then the dried polypropylene product was subjected to performance tests. The test results are shown in Table 1.

[0044] The polymerization method and conditions for the first propylene polymer component PP2 are the same as those for the first propylene polymer component PP1, except that the amount of hydrogenation catalyst added in step (ii) is changed to 2.55 ml, and the reaction time is continued for 5 minutes. The dried polypropylene product was then subjected to performance tests. The test results are shown in Table 1.

[0045] Table 1. Molecular chain structure information of the first propylene polymer components containing ultra-high molecular weight components: PP1 and PP2

[0046] <Testing Methods> The relevant test data for the obtained polymer products and foamed materials were obtained according to the following test methods: (1) Melt flow rate (MFR) (230℃, 2.16kg / 10min): The sample to be tested was tested according to ASTM D1238.

[0047] (2) Molecular weight and its distribution: The samples were tested using a PolymerChar high-temperature gel permeation chromatograph (GPC-IR6).

[0048] (3) Mechanical properties Bending performance: Tested according to GB / T9341-2008; Impact performance: Tested in accordance with GB / T1843-2008.

[0049] Examples 1-2 and Comparative Examples 1-3 were prepared using a solution blending method. The solution blending process involved simultaneously placing the first and second propylene polymer components into xylene and heating at 170°C for 70 minutes to dissolve them. After the polymers were uniformly dissolved, the polymer solution was placed in acetone and stirred to allow sedimentation. The sediment was then separated from the acetone through solid-liquid separation. The separated polymer was mixed with commonly used antioxidants and other additives in polyolefins. The mixed sediment was then dried in a vacuum oven at 30°C.

[0050] Examples 3-4 and Comparative Examples 4-5 were prepared using a screw extrusion melt blending method. The screw extrusion melt blending process was performed using a German HAAKE parallel co-rotating twin-screw extruder (HAAKERheomex PTW16OS). Simultaneously, the real-time torque of the mixture was tested using PolyLabOS software. The 10 screw temperatures of the twin-screw extruder were: 120℃-150℃-175℃-180℃-195℃-205℃-210℃-220℃-210℃-205℃, with the first screw temperature at 120℃ and the tenth screw temperature at 205℃. The feed rate was 8, and the rotation speed was 100 r / min.

[0051] Data for the obtained rigid-toughness balanced polypropylene compositions are shown in Tables 1 and 2.

[0052] Table 1. Components and Test Results of the Examples

[0053] Table 2 Comparative sample composition and test results

[0054] As can be seen from Tables 1-2 and Comparative Example 1, after blending K9928H with the first propylene polymer component PP1, the melt index decreases only slightly, ensuring a certain level of melt flowability while improving the rigidity and toughness of the material. Comparative Examples 1-3 show that if the amount of the first propylene polymer component PP1 added is too high, although the impact strength is significantly improved, the melt index and flexural modulus decrease considerably, resulting in a significant loss of rigidity and melt flowability. If the amount of the first propylene polymer component PP1 added is too low, the improvement in the rigidity and toughness of the material is not significant. This indicates that there is a suitable range for the amount of the first component PP1 added in the K9928H system; both excessively high and excessively low amounts are unsuitable.

[0055] Examples 3-4 and Comparative Examples 4-5 show that after K7760H is blended with the first propylene polymer component PP2, the melt index decreases only slightly, ensuring a certain level of melt flowability while improving the rigidity and toughness of the material. Comparative Example 5 also shows that excessive addition of the first propylene polymer component PP2, while improving the toughness of the material, results in a significant loss of rigidity and melt flowability. Therefore, there is a suitable range for the addition amount of the first component PP2 in the K7760H system.

[0056] This invention controls the ash content of the material from the source by utilizing the synergistic effect of a first propylene polymer and a second propylene polymer in a specific ratio, without relying on inorganic fillers or external toughening agents. Using ultra-high molecular weight polypropylene, its extended macromolecular chain conformation forms physical cross-linking nodes in the system, constructing a well-compatible network with the second component. This design successfully achieves a simultaneous increase in the material's flexural modulus (rigidity) and impact strength (toughness) while maintaining relatively stable melt flow properties. This overcomes the technical contradiction in traditional polypropylene materials where increased rigidity often leads to decreased toughness, or improved toughness is often accompanied by a loss of rigidity, achieving excellent rigidity... Resilience balance.

[0057] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A rigid-toughness balanced polypropylene composition, characterized in that, in, The composition comprises a first propylene polymer component and a second propylene polymer component; the first propylene polymer component contains a molecular weight M. W The ultra-high molecular weight polypropylene component has a molecular weight of ≥10,000,000; the content of the ultra-high molecular weight polypropylene component is 0.03-5.00 wt%, preferably 0.05-2.00 wt%; the number average molecular weight M of the ultra-high molecular weight polypropylene component is... n The peak molecular weight M of the propylene polymer p The ratio of M n (M W ≥10000000) / M p ≥10, preferably ≥30; Based on 100 parts by weight of the total weight of the rigid-toughness balanced polypropylene composition, the content of each component in the polypropylene composition is as follows: the amount of the first propylene polymer component is 5-25%; preferably 10%-25%; the amount of the second propylene polymer is 75-95 parts by weight, preferably 80-95 parts by weight.

2. The rigid-toughness balanced polypropylene composition according to claim 1, characterized in that, The second propylene polymer component is selected from impact-resistant polypropylene and / or random copolymer polypropylene; preferably, the second propylene polymer component is impact-resistant polypropylene.

3. The rigid-toughness balanced polypropylene composition according to any one of claims 1-2, characterized in that, The impact-resistant polypropylene has a melt index of 20-100 g / 10 min at 230°C and a load of 2.16 kg, and an ethylene mass percentage content of 7%-30%; preferably, the impact-resistant polypropylene has a melt index of 20-70 g / 10 min at 230°C and a load of 2.16 kg, and an ethylene mass percentage content of 7%-25%.

4. The rigid-toughness balanced polypropylene composition according to any one of claims 1-3, characterized in that, The weight ratio of the first propylene polymer component to the second propylene polymer component is (0.05-0.33):1, preferably (0.08-0.28):

1.

5. The rigid-toughness balanced polypropylene composition according to any one of claims 1-4, characterized in that, The method for preparing the first propylene polymer component employs two or more polymerization reaction stages arranged in sequence; the method includes the following steps: (i) In the presence of a polymerization catalyst and hydrogen, propylene undergoes a first-stage polymerization reaction for 0.1-10 hours to prepare a feed stream containing polypropylene-I component; (ii) After the first stage of polymerization, a hydrogenation catalyst is introduced into the system, and the polymerization reaction continues for 0.01-3 hours to obtain molecular weight M. W The reaction was then stopped to obtain the propylene polymer containing the ultra-high molecular weight polypropylene component; The molar ratio of the hydrogenation catalyst to the total amount of hydrogen in the polymerization system is 1 / 10000-1 / 100, preferably 1 / 10000-1 / 1000. The hydrogenation catalyst is a mixture of organometallic compounds and alkylaluminum compounds; Preferably, in the mixture, the molar ratio of aluminum in the alkylaluminum compound to the organometallic compound ranges from 5.5 to 10.0:1, more preferably from 5.5 to 8.0:1; preferably, the organometallic compound has the general formula R(R')-MX(X'), wherein: R and R' are each independently cyclopentadienyl, indene, or fluorenyl without or with substituents, wherein the substituents are preferably selected from methyl, ethyl, propyl, butyl, or cycloalkyl; M is a transition metal element, preferably selected from one or more of Fe, Ti, Zr, Cr, and Mn; X and X' are each independently a halogen atom, an alkyl group, or an alkoxy group.

6. The rigid-toughness balanced polypropylene composition according to any one of claims 1-5, characterized in that, The composition further includes antioxidants, nucleating agents, acid removers, light stabilizers, and other additives. The total amount of the additives is 0.5%-2%; preferably, the total amount of the additives is 0.5%-1%.

7. A method for preparing a rigid-toughness balanced polypropylene according to any one of claims 1-6, characterized in that, The rigid-toughness balanced polypropylene can be prepared by blending two components; the blending method can be solution blending or screw extrusion melt blending.

8. The method for preparing rigid-toughness balanced polypropylene according to claim 7, characterized in that, The solution blending method includes the following steps: The first propylene polymer component and the second propylene polymer component are simultaneously placed in a good solvent of polyolefin and heated to dissolve. After the polymer is dissolved evenly, the polymer solution is placed in a poor solvent of polymer and stirred to settle. The precipitate is separated from the poor solvent of polyolefin by solid-liquid separation. The separated polymer is mixed with the additives. The mixed precipitate is placed in a vacuum oven to dry.

9. The method for preparing rigid-toughness balanced polypropylene according to claims 7-8, characterized in that, The preferred solvents for the polyolefin are: petroleum ether, toluene, dichloromethane, chloroform, tetrahydrofuran, xylene, cyclohexane, trichlorobenzene, etc., with petroleum ether, xylene, and toluene being preferred; the dissolution temperature of the polyolefin with the preferred solvent is 100-200℃, and the dissolution time of the polyolefin with the preferred solvent is 30min-90min; the preferred solvents for the polyolefin are: acetone, ethanol, ethyl acetate, methanol, butyl acetate, isopropanol, n-butanol, etc., with acetone, ethanol, and methanol being preferred.

10. The method for preparing rigid-tough balanced polypropylene according to claim 7, characterized in that, The screw extrusion melt blending method includes the following steps: mixing a first propylene polymer component, a second propylene polymer component, and an additive, then melting and extruding the resulting mixture and granulating it to obtain the melt-reinforced polypropylene composition; wherein the melt extrusion is carried out in a twin-screw extruder; preferably, the length-to-diameter ratio of the screw in the twin-screw extruder is 10-100, and the extrusion temperature is 110-220℃.

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