HPP composite tarpaulin with weather resistance and preparation method thereof

Abstract

The invention relates to the technical field of HPP composite tarpaulin production, in particular to a weather-resistant HPP composite tarpaulin and a preparation method thereof. The composite material comprises the following components: HPP-S resin granules, HPP-T resin granules, TPO / SEBS elastomer composite granules, an HALS light stabilizer, a downstream antioxidant, talcum powder and a PP-g-MAH compatilizer, wherein the HPP-S resin granules are obtained by taking isotatic polypropylene as matrix resin and introducing a DMDBS nucleating agent and an HPP antioxidant for modification; the HPP-T resin granules are obtained by polymerizing propylene in a Ziegler-Natta catalytic system, sequentially introducing ethylene and propylene monomers, and modifying through an HPP antioxidant; the TPO / SEBS elastomer composite particles are obtained by mixing TPO and SEBS in proportion, the content of the TPO is 40 wt% to 60 wt%, and the content of the SEBS is 60 wt% to 40 wt%. Ethylene / propylene is introduced in the polymerization process of HPP-T resin to form an endogenous rubber phase, and a uniformly dispersed flexible phase is formed in a polypropylene matrix; the impact strength and low-temperature elongation at break of the finished tarpaulin can be remarkably improved, and the low-temperature toughness and ductility are effectively improved.

Description

Technical Field

[0001] This invention relates to the field of HPP composite tarpaulin production technology, and more specifically, to a weather-resistant HPP composite tarpaulin and its preparation method. Background Technology

[0002] Tarpaulin, as a flexible covering material widely used in outdoor environments, is mainly used in open-air storage, rain and sun protection, tents, sunshades, and transport vehicle tarpaulins. Among them, tarpaulin materials not only need to have excellent mechanical properties, but also must be able to withstand long-term outdoor natural environment tests, including ultraviolet radiation, high and low temperature cycles, wind and rain, and alternating heat and humidity.

[0003] However, existing polypropylene (PP) based tarpaulin materials are prone to brittle fracture or breakage in cold environments or under conditions of sudden temperature changes, which greatly reduces their safety. In view of this, we propose a weather-resistant HPP composite tarpaulin and its preparation method. Summary of the Invention

[0004] The purpose of this invention is to provide a weather-resistant HPP composite tarpaulin and its preparation method, in order to solve the problem mentioned in the background art that ordinary PP tarpaulin is prone to brittle fracture or breakage in cold environments or under sudden temperature changes.

[0005] To achieve the above objectives, the present invention provides a weather-resistant HPP composite tarpaulin, comprising the following components: HPP-S resin granules, HPP-T resin granules, TPO / SEBS elastomer composite granules, HALS light stabilizer, downstream antioxidant, talc, and PP-g-MAH compatibilizer. HPP-S resin granules are obtained by using isotactic polypropylene as the matrix resin and introducing DMDBS nucleating agent and HPP antioxidant for modification. HPP-T resin granules are obtained by polymerizing propylene in a Ziegler-Natta catalytic system (to obtain isotactic polypropylene reaction powder), and then sequentially introducing ethylene and propylene monomers, and modifying them with HPP antioxidants. TPO / SEBS elastomer composite particles are obtained by mixing TPO and SEBS in a certain proportion, with TPO content ranging from 40wt% to 60wt% and SEBS content ranging from 40wt% to 60wt%.

[0006] Preferably, the preparation steps of the HPP-S resin granules are as follows: Take 96-99 parts by weight of isotactic polypropylene, 0.05-0.12 parts by weight of DMDBS nucleating agent and HPP antioxidant, respectively; Isotactic polypropylene, nucleating agent, and HPP antioxidant are added to a twin-screw melt-mixing extruder and melt-blended at a temperature of 180-220℃, with the shear rate controlled at 50-200 s. -1 ; The mixture is extruded and granulated, then cooled to form granules, to obtain HPP-S resin granules.

[0007] Preferably, the particle size of the HPP-S resin granules is 3-6 mm.

[0008] Preferably, the preparation steps of the HPP-T resin granules are as follows: Propylene was polymerized in a loop slurry reactor at 65-75°C and 3.5-6.0 MPa using a MgCl2-supported TiCl4 solid catalyst (Ziegler-Natta type, Ti content 2.0-3.5 wt%) as the main catalyst, triethylaluminum as a co-catalyst (Al / Ti molar ratio 100-300), and dicyclopentyldimethoxysilane as an external electron donor (Si / Al molar ratio 0.05-0.20) for 30-90 min. The molecular weight was adjusted by introducing hydrogen (10-150 ppm) into the reactor to obtain spherical, porous polypropylene powder. Residual monomers and diluents were removed by vacuum flash evaporation and nitrogen purging. The aforementioned polypropylene powder was directly conveyed (under an inert atmosphere) to a gas-phase fluidized bed reactor. Under conditions of 70-85℃ and 1.5-2.5MPa, ethylene monomer and propylene monomer were sequentially introduced, and polymerization continued under the same catalytic system to form a rubber phase with a particle size of 0.2-0.5μm. In the rubber phase, ethylene accounted for 10wt% of the total mass of the final HPP-T resin granules, and propylene accounted for 2wt% of the total mass of the final HPP-T resin granules. After polymerization, HPP antioxidant is added to the reaction system to remove unreacted monomers, and the mixture is dried and granulated to obtain HPP-T resin granules.

[0009] Preferably, the HPP-T resin granules have a particle size of 1.5-2 mm. The small size of the HPP-T resin granules facilitates downstream melt blending, and the smaller particle size is beneficial for rapid melting and uniform dispersion of the rubber phase during the blending process, thereby improving the tear strength and impact resistance of the final tarpaulin.

[0010] Preferably, the polypropylene powder has a particle size of 600-800 μm, a porosity of 0.2-0.4, a xylene-soluble content ≤3.0 wt%, and a bulk density of 0.35-0.50 g / cm³. 3 .

[0011] Preferably, the HPP antioxidant is obtained by compounding Irganox 1010 and Irgafos 168, and the mass ratio of Irganox 1010 to Irgafos 168 is 1:3. In the preparation of HPP-S resin granules, the total amount of HPP antioxidant added accounts for 0.08-0.15 wt% of the total mass of the final HPP-S resin granules; In the preparation of HPP-T resin granules, the total amount of HPP antioxidant added accounts for 0.1-0.3 wt% of the total mass of the final HPP-T resin granules.

[0012] On the other hand, the present invention provides a method for preparing a weather-resistant HPP composite tarpaulin, for use in any one of the above-mentioned weather-resistant HPP composite tarpaulins, comprising the following steps: Weigh the following raw materials: 70-80 parts by weight of HPP-S resin granules, 30-35 parts by weight of HPP-T resin granules, 10-14 parts by weight of TPO / SEBS elastomer composite granules, 0.3-0.6 parts by weight of HALS light stabilizer, 0.12-0.16 parts by weight of downstream antioxidant, 3-5 parts by weight of talc, and 0.5-2.0 parts by weight of PP-g-MAH compatibilizer; HPP-S resin granules and HPP-T resin granules were premixed in a certain proportion, and TPO / SEBS elastomer composite granules, talc powder and PP-g-MAH compatibilizer were added to the premix in sequence. The thoroughly mixed premixed material is added to a twin-screw melt mixing extruder and extruded at a temperature of 200-240℃ for 140-180 seconds. -1 The shear rate was measured, and the melt mixing process lasted 4-6 minutes. Add downstream antioxidants and HALS light stabilizers in the later stage of melt mixing, and stir evenly for 1-3 minutes; The molten mixture is extruded through an extruder die, cooled by air cooling, and cut into composite tarpaulin masterbatch with a particle size of 3-6mm to obtain the final HPP composite granules; HPP composite granules are calendered into a film at a temperature of 200–240℃, and then cooled and wound to obtain the finished tarpaulin.

[0013] Preferably, the premixing ratio of HPP-S to HPP-T granules is 2~2.7:1.

[0014] Preferably, the downstream antioxidant is obtained by compounding Irganox 1010 and Irgafos 168, and the mass ratio of Irganox 1010 to Irgafos 168 is 1~1.3:1.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. In the weather-resistant HPP composite tarpaulin and its preparation method, ethylene / propylene is introduced during the polymerization of HPP-T resin to form an endogenous rubber phase, and the particle size of the rubber phase is controlled within the range of 0.2-0.5μm, forming a uniformly dispersed flexible phase in the polypropylene matrix; this can significantly improve the impact strength and low-temperature elongation at break of the finished tarpaulin, and effectively improve its low-temperature toughness and ductility.

[0016] 2. In the weather-resistant HPP composite tarpaulin and its preparation method, TPO / SEBS elastomer composite particles are introduced to optimize the network structure of the flexible phase, thereby enhancing the low-temperature flexibility and folding durability of the tarpaulin.

[0017] 3. In the weather-resistant HPP composite tarpaulin and its preparation method, DMDBS nucleating agent is introduced and the isotactic polypropylene ratio is adjusted during the preparation of HPP-S resin granules to promote rapid nucleation of isotactic polypropylene segments, improve crystallinity and grain uniformity; thereby giving the tarpaulin excellent dimensional stability and rigidity, making it have better creep resistance, deformation resistance, heat resistance and weather resistance when used outdoors for a long time. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] The weather-resistant HPP composite tarpaulin of the present invention comprises the following components: HPP-S resin granules, HPP-T resin granules, TPO / SEBS elastomer composite granules, HALS light stabilizer, downstream antioxidant, talc, and 0.5-2.0 parts by weight of PP-g-MAH compatibilizer. HPP-S resin granules are obtained by using isotactic polypropylene as the matrix resin and introducing DMDBS nucleating agent and HPP antioxidant for modification. HPP-T resin granules are obtained by polymerizing propylene in a Ziegler-Natta catalytic system (to obtain isotactic polypropylene reaction powder), and then sequentially introducing ethylene and propylene monomers, and modifying them with HPP antioxidants. Furthermore, the premixing ratio of HPP-S to HPP-T granules is 2~2.7:1; TPO / SEBS elastomer composite particles are obtained by mixing TPO and SEBS in a certain proportion, with TPO content ranging from 40wt% to 60wt% and SEBS content ranging from 40wt% to 60wt%.

[0020] TPO was purchased from Dongguan Jinshixiang Plastic Raw Materials Co., Ltd. SEBS was purchased from Yucheng (Hongji) Plastics Dongguan Co., Ltd. Titanium tetrachloride (the main active component is titanium tetrachloride, and the support is magnesium chloride) was purchased from Liaoning Xiangyang Kehua Group as the main catalyst; HALS light stabilizer procurement is handled by Zhiyi Chemical Co., Ltd., CAS: 41556-26-7; Irganox 1010 was purchased from Shanghai Puvilli Special Materials Co., Ltd. Irgafos 168 was purchased from Dongguan Subang Plastic Raw Materials Co., Ltd., CAS: 31570-04-4 Talc powder was purchased from Shanghai Juqian New Material Development Co., Ltd., CAS: 14807-96-6; PP-g-MAH compatibilizer was purchased from Nantong Runfeng Petrochemical Co., Ltd. DMDBS nucleating agent was purchased from Shanghai Yuanye Biotechnology Co., Ltd., CAS: 81541-12-0; The isotactic polypropylene was purchased from Dongguan Yili Plastics Co., Ltd., CAS: 9003-07-0.

[0021] The performance indicators of the prepared HPP-S are as follows: Isotacticity ≥ 97%; Crystallinity ≥ 60%; Melting point 162–166℃; Melt flow index (MFR, 230℃ / 2.16kg) 0.85–1.35g / 10min.

[0022] The prepared HPP-T has the following performance indicators: Basic isotacticity ≥ 95% Endogenous rubber phase content: 10–15 wt%; Melting point 159–164℃ Melt flow index (MFR, 230℃ / 2.16kg) 0.8–2.0 g / 10min; Example 1: A method for preparing HPP-S resin granules, comprising the following steps: Take 96 parts by weight of isotactic polypropylene, 0.05 parts by weight of DMDBS nucleating agent and HPP antioxidant respectively; Isotactic polypropylene, nucleating agent, and HPP antioxidant were added to a twin-screw melt-mixing extruder and melt-blended at 190°C with a shear rate controlled at 170 s⁻¹. -1 ; The mixture was extruded and granulated, then cooled to form granules, resulting in HPP-S resin granules with a particle size of 3 mm.

[0023] The HPP antioxidant is obtained by compounding Irganox 1010 and Irgafos 168, and the mass ratio of Irganox 1010 to Irgafos 168 is 1:3. Furthermore, the total amount of HPP antioxidant added in the preparation of HPP-S resin granules accounts for 0.08 wt% of the total mass of the final HPP-S resin granules.

[0024] Example 2: A method for preparing HPP-S resin granules, comprising the following steps: Take 96 parts by weight of isotactic polypropylene, 0.09 parts by weight of DMDBS nucleating agent and HPP antioxidant respectively; Isotactic polypropylene, nucleating agent, and HPP antioxidant were added to a twin-screw melt-mixing extruder and melt-blended at 190°C with a shear rate controlled at 120 s⁻¹. -1 ; The mixture was extruded and granulated, then cooled to form granules, resulting in HPP-S resin granules with a particle size of 3 mm.

[0025] The HPP antioxidant is obtained by compounding Irganox 1010 and Irgafos 168, and the mass ratio of Irganox 1010 to Irgafos 168 is 1:3. Furthermore, the total amount of HPP antioxidant added in the preparation of HPP-S resin granules accounts for 0.08 wt% of the total mass of the final HPP-S resin granules.

[0026] Example 3: A method for preparing HPP-S resin granules, comprising the following steps: Take 96 parts by weight of isotactic polypropylene, 0.12 parts by weight of DMDBS nucleating agent and HPP antioxidant respectively; Isotactic polypropylene, nucleating agent, and HPP antioxidant were added to a twin-screw melt-mixing extruder and melt-blended at 190°C with a shear rate controlled at 160 s⁻¹. -1 ; The mixture was extruded and granulated, then cooled to form granules, resulting in HPP-S resin granules with a particle size of 3 mm.

[0027] The HPP antioxidant is obtained by compounding Irganox 1010 and Irgafos 168, and the mass ratio of Irganox 1010 to Irgafos 168 is 1:3. Furthermore, the total amount of HPP antioxidant added in the preparation of HPP-S resin granules accounts for 0.08 wt% of the total mass of the final HPP-S resin granules.

[0028] Example 4: A method for preparing HPP-S resin granules, comprising the following steps: Take 97 parts by weight of isotactic polypropylene, 0.09 parts by weight of DMDBS nucleating agent and HPP antioxidant respectively; Isotactic polypropylene, nucleating agent, and HPP antioxidant were added to a twin-screw melt-mixing extruder and melt-blended at 190°C with a shear rate controlled at 120 s⁻¹. -1 ; The mixture was extruded and granulated, then cooled to form granules, resulting in HPP-S resin granules with a particle size of 3 mm.

[0029] The HPP antioxidant is obtained by compounding Irganox 1010 and Irgafos 168, and the mass ratio of Irganox 1010 to Irgafos 168 is 1:3. Furthermore, the total amount of HPP antioxidant added in the preparation of HPP-S resin granules accounts for 0.08 wt% of the total mass of the final HPP-S resin granules.

[0030] Example 5: A method for preparing HPP-S resin granules, comprising the following steps: Take 99 parts by weight of isotactic polypropylene, 0.09 parts by weight of DMDBS nucleating agent and HPP antioxidant respectively; Isotactic polypropylene, nucleating agent, and HPP antioxidant were added to a twin-screw melt-mixing extruder and melt-blended at 190°C with a shear rate controlled at 120 s⁻¹. -1 ; The mixture was extruded and granulated, then cooled to form granules, resulting in HPP-S resin granules with a particle size of 3 mm.

[0031] The HPP antioxidant is obtained by compounding Irganox 1010 and Irgafos 168, and the mass ratio of Irganox 1010 to Irgafos 168 is 1:3. Furthermore, the total amount of HPP antioxidant added in the preparation of HPP-S resin granules accounts for 0.08 wt% of the total mass of the final HPP-S resin granules.

[0032] Example 6: A method for preparing HPP-S resin granules, comprising the following steps: Take 99 parts by weight of isotactic polypropylene, 0.09 parts by weight of DMDBS nucleating agent and HPP antioxidant respectively; Isotactic polypropylene, nucleating agent, and HPP antioxidant were added to a twin-screw melt-mixing extruder and melt-blended at 190°C with a shear rate controlled at 120 s⁻¹. -1 ; The mixture was extruded and granulated, then cooled to form granules, resulting in HPP-S resin granules with a particle size of 3 mm.

[0033] The HPP antioxidant is obtained by compounding Irganox 1010 and Irgafos 168, and the mass ratio of Irganox 1010 to Irgafos 168 is 1:3. Furthermore, the total amount of HPP antioxidant added in the preparation of HPP-S resin granules accounts for 0.12 wt% of the total mass of the final HPP-S resin granules.

[0034] To verify the effects of the total addition amount of isotactic polypropylene, DMDBS nucleating agent, and HPP antioxidant on the properties of HPP-S resin granules in the above embodiments, the following experiments were conducted: This experiment was conducted on the HPP-S resin granules prepared in Examples 1-6. Sample preparation: HPP-S resin granule samples were prepared according to the methods in Examples 1-6, and were recorded as test groups A, B, C, D, E and F in sequence; Performance testing Isotacticity determination: Dissolve HPP-S resin granules in a dechlorinated solvent (such as 1,2,4-trichlorobenzene) at a concentration of approximately 20–30 mg / mL, heat to 120–130°C, and mix thoroughly. The solution was placed in an NMR tube, and the 13C spectrum was measured using a 13C-NMR nuclear magnetic resonance spectrometer. The peak areas (mm, mr, rr) of the isotactic sequence were analyzed, and the isotacticity was calculated. Each sample was measured three times, and the average value was taken as the final isotacticity.

[0035] Among them, isotacticity is used as an index to measure the regularity of polypropylene molecular chains. High isotacticity means that polypropylene chains are well-regulated, the chain segments are highly consistent along the main chain direction, and it is easy to form crystalline regions. Specifically, highly isotactic segments result in a dense polypropylene crystal structure, leading to stable mechanical properties and improved heat resistance. Therefore, high isotacticity is beneficial for forming a stable crystalline network, enhancing the mechanical strength, heat resistance, and long-term weather resistance of the tarpaulin.

[0036] Crystallinity determination Cut HPP-S resin granules into small pieces of approximately 5-10 mg and place them in an aluminum crucible; heat to 200-220℃ and hold for 2 minutes; cool to room temperature and reheat to 200-220℃; measure the melting peak area. : in, (Theoretical melting enthalpy of pure isotactic PP); Specifically, crystallinity determines the rigidity and thermomechanical stability of a material. High crystallinity enables HPP composite tarpaulins to maintain dimensional and structural stability in outdoor environments, while also enhancing weather resistance.

[0037] Melt flow index (MFR) is determined based on ISO 1133 standard concerning the melt mass flow rate (MFR) of thermoplastics. Specifically: Add HPP-S resin granules into the barrel within 4-5 seconds to reduce degradation during preheating. After loading, use a pressure bar to compact the material to remove air bubbles. After adding the material, preheat at 230℃ for 4-6 minutes, measure the amount of molten material flowing out within a certain time, and calculate the MFR (g / 10min). Each sample is measured three times, and the average value is taken. Among them, MFR is a bridging parameter between processing and performance. By adjusting the MFR of HPP-S granules, the processability and mechanical properties of the finished product can be balanced, ensuring the uniformity of tarpaulin thickness and tensile toughness.

[0038] Specific testing indicators are shown in Table 1.

[0039] Table 1: Performance indicators of HPP-S resin granules prepared in Examples 1-5 From the data in Table 1 for experimental groups A, B, and C, we can see that: When the isotactic polypropylene content remains constant, as the DMDBS nucleating agent increases, the isotacticity changes only slightly, but the crystallinity increases significantly. High crystallinity is beneficial for enhancing grain uniformity and rigidity, which can be used to improve the dimensional stability, creep resistance and light aging resistance of tarpaulins.

[0040] However, the melt flow index decreased as the DMDBS nucleating agent increased, indicating that the increased grain size led to a slight decrease in melt fluidity. The melt flow index affects the surface smoothness and thickness uniformity of the molded tarpaulin.

[0041] Meanwhile, according to experimental groups B, D and E, as the content of isotactic polypropylene gradually increases, the isotacticity also increases (from 97.1% to 97.9%). The isotacticity can improve the regularity of the crystal regions, thereby improving the heat resistance and light aging resistance. As the content of isotactic polypropylene increases, the crystallinity also increases slightly, indicating that isotactic polypropylene has a positive effect on both isotacticity and crystallinity. However, the melt flow index decreases as the isotactic polypropylene content increases, which affects the uniformity of the thickness and the surface smoothness of the molded tarpaulin.

[0042] Furthermore, combining experimental groups E and F, it can be seen that when other components remain unchanged, the melt index changes most significantly when the total amount of HPP antioxidant added is changed alone, indicating that the melt flowability is slightly improved (the antioxidant can play a lubricating role in the melting process). The slight decrease in crystallinity indicates a minor reduction in rigidity and dimensional stability, but the change is small and has little impact on the overall rigidity of the tarpaulin.

[0043] Example 6 above is taken as the optimal example for preparing HPP-S resin granules. To demonstrate the effect of DMDBS nucleating agent and isotactic polypropylene on HPP-S resin granules, the following comparative examples are used: Comparative Example 1: Using the method of Example 6, keeping all other raw material components unchanged, the DMDBS nucleating agent was changed to 0.05 parts by weight (Group A) and 0.18 parts by weight (Group B). Comparative Example 2: Using the method of Example 6, keeping other raw material components unchanged, the isotactic polypropylene was changed to 90 parts by weight (Group C) and 110 parts by weight (Group D). Using the same test methods as described above for the HPP-S resin granules prepared in Examples 1-6, the HPP-S resin granules prepared in Comparative Example 1 and Comparative Example 2 were tested, and the specific test indicators are shown in Table 2. Table 2: Performance indicators of HPP-S resin granules prepared in Example 6, Comparative Example 1 and Comparative Example 2 According to the data in Table 2, for Example 6, Group A, and Group B: When the DMDBS nucleating agent changed significantly, the crystallinity of group A was close to the lower limit (less than 60%), proving that when the DMDBS nucleating agent content is too low, it will lead to insufficient crystal nuclei, which in turn will lead to a decrease in the rigidity and dimensional stability of the tarpaulin. When the crystallinity is too high (Group B), it will lead to excessively dense grains, which in turn will reduce the fluidity of the melt and increase the difficulty of processing.

[0044] In summary, it can be seen that when the DMDBS nucleating agent deviates from the standard, it will affect the uniformity of the crystal region, which in turn will affect the performance of the subsequently prepared tarpaulin.

[0045] Based on the data from Example 6, Group C, and Group D, it can be concluded that: When the isotactic polypropylene content is too low, the isotacticity and crystallinity are both lower than the standard, while the melt index is too high, and the performance is significantly reduced. When the content of isotactic polypropylene is too high, the crystallinity is higher than the standard, the melt index is lower than the lower limit (0.85g / 10min), which leads to increased rigidity but decreased processability and insufficient melt flowability. In summary, the performance of HPP-S resin granules is highly sensitive to the DMDBS nucleating agent and isotactic polypropylene. Changing the content of DMDBS nucleating agent and isotactic polypropylene will affect its performance.

[0046] Furthermore, to clarify the performance indicators of the prepared HPP-T resin granules, the following examples were designed: Example 7: A method for preparing HPP-T resin granules, comprising the following steps: Propylene was polymerized in a loop slurry reactor at 75°C and 5.0 MPa using MgCl2-supported TiCl4 solid catalyst as the main catalyst, triethylaluminum as the co-catalyst, and dicyclopentyldimethoxysilane as the external electron donor. The polymerization was carried out in the propylene slurry for 75 min. The molecular weight was adjusted by introducing hydrogen into the reactor to obtain polypropylene powder. Residual monomers and diluents were removed by vacuum flash evaporation and nitrogen purging. The aforementioned polypropylene powder was directly fed into a gas-phase fluidized bed reactor. Under conditions of 75°C and 1.8 MPa, ethylene monomer and propylene monomer were sequentially introduced, and polymerization continued under the same catalytic system to form a rubber phase with a particle size of 0.2 μm. In the rubber phase, ethylene accounted for 10 wt% of the total mass of the final HPP-T resin granules, and propylene accounted for 2 wt% of the total mass of the final HPP-T resin granules. After polymerization, HPP antioxidant is added to the reaction system to remove unreacted monomers, and the mixture is dried and granulated to obtain HPP-T resin granules with a particle size of 1.5 mm.

[0047] The polypropylene powder has a particle size of 720 μm, a porosity of 0.3, a xylene-soluble content of ≤3.0 wt%, and a bulk density of 0.40 g / cm³. 3 ; HPP antioxidant is a compound of Irganox 1010 and Irgafos 168, with a mass ratio of Irganox 1010 to Irgafos 168 of 1:3. In the preparation of HPP-T resin granules, the total amount of HPP antioxidant added accounts for 0.18 wt% of the total mass of the final HPP-T resin granules.

[0048] Example 8: A method for preparing HPP-T resin granules, comprising the following steps: Propylene was polymerized in a loop slurry reactor at 75°C and 5.0 MPa using MgCl2-supported TiCl4 solid catalyst as the main catalyst, triethylaluminum as the co-catalyst, and dicyclopentyldimethoxysilane as the external electron donor. The polymerization was carried out in the propylene slurry for 75 min. The molecular weight was adjusted by introducing hydrogen into the reactor to obtain polypropylene powder. Residual monomers and diluents were removed by vacuum flash evaporation and nitrogen purging. The aforementioned polypropylene powder was directly fed into a gas-phase fluidized bed reactor. Under conditions of 75°C and 1.8 MPa, ethylene monomer and propylene monomer were sequentially introduced, and polymerization continued under the same catalytic system to form a rubber phase with a particle size of 0.3 μm. In the rubber phase, ethylene accounted for 10 wt% of the total mass of the final HPP-T resin granules, and propylene accounted for 2 wt% of the total mass of the final HPP-T resin granules. After polymerization, HPP antioxidant is added to the reaction system to remove unreacted monomers, and the mixture is dried and granulated to obtain HPP-T resin granules with a particle size of 1.5 mm.

[0049] The polypropylene powder has a particle size of 720 μm, a porosity of 0.3, a xylene-soluble content of ≤3.0 wt%, and a bulk density of 0.40 g / cm³. 3 ; HPP antioxidant is a compound of Irganox 1010 and Irgafos 168, with a mass ratio of Irganox 1010 to Irgafos 168 of 1:3. In the preparation of HPP-T resin granules, the total amount of HPP antioxidant added accounts for 0.18 wt% of the total mass of the final HPP-T resin granules.

[0050] Example 9: A method for preparing HPP-T resin granules, comprising the following steps: Propylene was polymerized in a loop slurry reactor at 75°C and 5.0 MPa using MgCl2-supported TiCl4 solid catalyst as the main catalyst, triethylaluminum as the co-catalyst, and dicyclopentyldimethoxysilane as the external electron donor. The polymerization was carried out in the propylene slurry for 75 min. The molecular weight was adjusted by introducing hydrogen into the reactor to obtain polypropylene powder. Residual monomers and diluents were removed by vacuum flash evaporation and nitrogen purging. The aforementioned polypropylene powder was directly fed into a gas-phase fluidized bed reactor. Under conditions of 75°C and 1.8 MPa, ethylene monomer and propylene monomer were sequentially introduced, and polymerization continued under the same catalytic system to form a rubber phase with a particle size of 0.5 μm. In the rubber phase, ethylene accounted for 10 wt% of the total mass of the final HPP-T resin granules, and propylene accounted for 2 wt% of the total mass of the final HPP-T resin granules. After polymerization, HPP antioxidant is added to the reaction system to remove unreacted monomers, and the mixture is dried and granulated to obtain HPP-T resin granules with a particle size of 1.5 mm.

[0051] The polypropylene powder has a particle size of 720 μm, a porosity of 0.3, a xylene-soluble content of ≤3.0 wt%, and a bulk density of 0.40 g / cm³. 3 ; HPP antioxidant is a compound of Irganox 1010 and Irgafos 168, with a mass ratio of Irganox 1010 to Irgafos 168 of 1:3. In the preparation of HPP-T resin granules, the total amount of HPP antioxidant added accounts for 0.18 wt% of the total mass of the final HPP-T resin granules.

[0052] Comparative Example 3: The method of Example 8 was used, except that the particle size of the rubber phase was changed to 0.15 μm.

[0053] Comparative Example 4: The method of Example 8 was used, but the particle size of the rubber phase was changed to 1 μm.

[0054] Comparative Example 5: Using the method of Example 8, the above polypropylene powder was directly fed into a gas-phase fluidized bed reactor at 75°C and 1.8 MPa without introducing ethylene / propylene.

[0055] To verify the effect of rubber phase particle size on the properties of HPP-T resin granules in the above examples (7-9) and comparative examples (3-4), the following experiments were conducted: This experiment was conducted to test the HPP-T resin granules prepared in Examples 7-9 and Comparative Examples 3-4. Sample preparation: HPP-T resin granule samples were prepared according to the methods of Examples 7-9 and Comparative Examples 3-4; The performance tests are as follows, including the impact performance test: The impact properties of the material were evaluated using a Charpy notched impact testing machine. The test conditions were set to two environments: room temperature (23℃) and low temperature (-20℃). The samples under the low temperature condition needed to be pre-equilibrated in a constant temperature chamber for 2 hours to ensure temperature uniformity. Each group of samples contained at least 5 parallel samples, and the average value was taken as the final result.

[0056] Tensile property test: Dumbbell-shaped tensile specimens were prepared according to ISO 527-2 standard; The tests were conducted using a universal testing machine at a tensile speed of 50 mm / min, and were performed at both 23°C and -20°C. The low-temperature test specimens were pretreated in a constant-temperature chamber. Five parallel samples were tested for each group of specimens, and the average value was used to evaluate the elongation at break of the material.

[0057] Table 3: Performance indicators of HPP-T resin granules prepared in Examples 7-9 and Comparative Examples 3-5 According to the impact and tensile data in Table 3, under the same experimental and preparation conditions: The HPP-T resin granules prepared by Examples 7-9 showed significantly improved impact strength at both room temperature and low temperature. The results of the elongation at break test show that HPP-T resin granules have excellent ductility at room temperature (greater than 300%) and can still maintain excellent elongation at low temperature (up to 265%). The toughness of Comparative Example 3 (particle size too small, 0.15 μm) and Comparative Example 4 (particle size too large, 1 μm) was inferior to that of Examples 7-9, indicating that the optimal rubber phase particle size is controlled in the range of 0.2–0.5 μm, especially around 0.3 μm where the performance is best.

[0058] Meanwhile, when ethylene / propylene is not introduced, Comparative Example 5 has no rubber phase. As can be seen from Comparative Example 5 in Table 3, the performance indicators of the HPP-T resin granules prepared according to Comparative Example 5 are significantly reduced. That is, the toughness and low-temperature ductility of the HPP-T resin granules prepared according to Comparative Example 5 are greatly weakened, and the material tends to brittle failure. In contrast, in Examples 7–9, the rubber phase can significantly improve the impact strength, indicating that the rubber phase, as a flexible phase, can absorb impact energy and hinder crack propagation during crack propagation. Comparative Example 5, serving as the extreme control for the absence of the rubber phase, further demonstrates that the toughness and ductility of the material are significantly deteriorated without the rubber phase. The rubber phase is the core determinant of the toughness and low-temperature performance of HPP-T resin. The absence of the rubber phase in HPP-T results in a comprehensive degradation of its mechanical properties, verifying the importance of the rubber phase.

[0059] Based on the HPP-S resin granules and HPP-T resin granules prepared through Examples 1-9 above, and using the HPP-S resin granules prepared through Example 6 and the HPP-T resin granules prepared through Example 8 respectively, a weather-resistant HPP composite tarpaulin was prepared by weighing the following raw materials: 70-80 parts by weight of HPP-S resin granules (prepared in Example 6), 30-35 parts by weight of HPP-T resin granules (prepared in Example 8), 10-14 parts by weight of TPO / SEBS elastomer composite granules, 0.3-0.6 parts by weight of HALS light stabilizer, 0.12-0.16 parts by weight of downstream antioxidant, 3-5 parts by weight of talc, and 0.5-2.0 parts by weight of PP-g-MAH compatibilizer; Example 10: A method for preparing a weather-resistant HPP composite tarpaulin, comprising the following steps: 70 parts by weight of HPP-S resin granules and 30 parts by weight of HPP-T resin granules were premixed in proportion, and 10 parts by weight of TPO / SEBS elastomer composite granules, 5 parts by weight of talc powder and 0.5 parts by weight of PP-g-MAH compatibilizer were added to the premix in sequence. The thoroughly mixed premixed material is added to a twin-screw melt-mixing extruder and extruded at 220°C for 165 seconds. -1 The shear rate was measured, and the melt mixing was carried out for 5 minutes. After the melt mixing stage, 0.12 parts by weight of downstream antioxidant and 0.4 parts by weight of HALS light stabilizer are added and stirred evenly for 2 minutes. The downstream antioxidant is obtained by compounding Irganox 1010 and Irgafos 168, and the mass ratio of Irganox 1010 to Irgafos 168 is 1:1. The TPO / SEBS elastomer composite particles are obtained by mixing TPO and SEBS in a certain proportion, with TPO content of 40 wt% and SEBS content of 60 wt%. The molten mixture is extruded through an extruder die, cooled by air cooling, and cut into composite tarpaulin masterbatch with a particle size of 3-6mm to obtain the final HPP composite granules; HPP composite granules are calendered into a film at 220°C, and then cooled and wound to obtain the finished tarpaulin.

[0060] Example 11: A method for preparing a weather-resistant HPP composite tarpaulin, comprising the following steps: premixing 70 parts by weight of HPP-S resin granules and 33 parts by weight of HPP-T resin granules in a certain proportion, and sequentially adding 10 parts by weight of TPO / SEBS elastomer composite granules, 5 parts by weight of talc powder and 0.5 parts by weight of PP-g-MAH compatibilizer to the premix; The thoroughly mixed premixed material is added to a twin-screw melt-mixing extruder and extruded at 220°C for 165 seconds. -1 The shear rate was measured, and the melt mixing was carried out for 5 minutes. After the melt mixing stage, 0.12 parts by weight of downstream antioxidant and 0.4 parts by weight of HALS light stabilizer are added and stirred evenly for 2 minutes. The downstream antioxidant is obtained by compounding Irganox 1010 and Irgafos 168, and the mass ratio of Irganox 1010 to Irgafos 168 is 1:1. The TPO / SEBS elastomer composite particles are obtained by mixing TPO and SEBS in a certain proportion, with TPO content of 40 wt% and SEBS content of 60 wt%. The molten mixture is extruded through an extruder die, cooled by air cooling, and cut into composite tarpaulin masterbatch with a particle size of 3-6mm to obtain the final HPP composite granules; HPP composite granules are calendered into a film at 220°C, and then cooled and wound to obtain the finished tarpaulin.

[0061] Example 12: A method for preparing a weather-resistant HPP composite tarpaulin, comprising the following steps: premixing 70 parts by weight of HPP-S resin granules and 35 parts by weight of HPP-T resin granules in a certain proportion, and sequentially adding 10 parts by weight of TPO / SEBS elastomer composite granules, 5 parts by weight of talc powder and 0.5 parts by weight of PP-g-MAH compatibilizer to the premix; The thoroughly mixed premixed material is added to a twin-screw melt-mixing extruder and extruded at 220°C for 165 seconds. -1 The shear rate was measured, and the melt mixing was carried out for 5 minutes. After the melt mixing stage, 0.12 parts by weight of downstream antioxidant and 0.4 parts by weight of HALS light stabilizer are added and stirred evenly for 2 minutes. The downstream antioxidant is obtained by compounding Irganox 1010 and Irgafos 168, and the mass ratio of Irganox 1010 to Irgafos 168 is 1:1. The TPO / SEBS elastomer composite particles are obtained by mixing TPO and SEBS in a certain proportion, with TPO content of 40 wt% and SEBS content of 60 wt%. The molten mixture is extruded through an extruder die, cooled by air cooling, and cut into composite tarpaulin masterbatch with a particle size of 3-6mm to obtain the final HPP composite granules; HPP composite granules are calendered into a film at 220°C, and then cooled and wound to obtain the finished tarpaulin.

[0062] Example 13: A method for preparing a weather-resistant HPP composite tarpaulin, comprising the following steps: premixing 75 parts by weight of HPP-S resin granules and 30 parts by weight of HPP-T resin granules in a certain proportion, and sequentially adding 10 parts by weight of TPO / SEBS elastomer composite granules, 5 parts by weight of talc powder and 0.5 parts by weight of PP-g-MAH compatibilizer to the premix; The thoroughly mixed premixed material is added to a twin-screw melt-mixing extruder and extruded at 220°C for 165 seconds. -1 The shear rate was measured, and the melt mixing was carried out for 5 minutes. After the melt mixing stage, 0.12 parts by weight of downstream antioxidant and 0.4 parts by weight of HALS light stabilizer are added and stirred evenly for 2 minutes. The downstream antioxidant is obtained by compounding Irganox 1010 and Irgafos 168, and the mass ratio of Irganox 1010 to Irgafos 168 is 1:1. The TPO / SEBS elastomer composite particles are obtained by mixing TPO and SEBS in a certain proportion, with TPO content of 40 wt% and SEBS content of 60 wt%. The molten mixture is extruded through an extruder die, cooled by air cooling, and cut into composite tarpaulin masterbatch with a particle size of 3-6mm to obtain the final HPP composite granules; HPP composite granules are calendered into a film at 220°C, and then cooled and wound to obtain the finished tarpaulin.

[0063] Example 14: A method for preparing a weather-resistant HPP composite tarpaulin, comprising the following steps: premixing 80 parts by weight of HPP-S resin granules and 30 parts by weight of HPP-T resin granules in a certain proportion, and sequentially adding 10 parts by weight of TPO / SEBS elastomer composite granules, 5 parts by weight of talc powder and 0.5 parts by weight of PP-g-MAH compatibilizer to the premix; The thoroughly mixed premixed material is added to a twin-screw melt-mixing extruder and extruded at 220°C for 165 seconds. -1 The shear rate was measured, and the melt mixing was carried out for 5 minutes. After the melt mixing stage, 0.12 parts by weight of downstream antioxidant and 0.4 parts by weight of HALS light stabilizer are added and stirred evenly for 2 minutes. The downstream antioxidant is obtained by compounding Irganox 1010 and Irgafos 168, and the mass ratio of Irganox 1010 to Irgafos 168 is 1:1. The TPO / SEBS elastomer composite particles are obtained by mixing TPO and SEBS in a certain proportion, with TPO content of 40 wt% and SEBS content of 60 wt%. The molten mixture is extruded through an extruder die, cooled by air cooling, and cut into composite tarpaulin masterbatch with a particle size of 3-6mm to obtain the final HPP composite granules; HPP composite granules are calendered into a film at 220°C, and then cooled and wound to obtain the finished tarpaulin.

[0064] The testing experiments for the finished tarpaulin are as follows: Cold cracking temperature (°C): The tarpaulin is cut into strips of specified size and pre-conditioned under ambient conditions. The samples are then sequentially placed in a series of decreasing temperature freezer environments (e.g., 0°C, -10°C, -20°C, -25°C, -30°C, -35°C). Once equilibrium is reached, the samples are immediately subjected to rapid bending or bending operations at the angles and number of bends specified in the standard. At each temperature point, the surface of the sample is observed for visible cracks; the first appearance of a crack is recorded as the cold cracking temperature of that tarpaulin sample. Elongation retention %: Finished rolls or cut samples were laid flat and placed in a QUV aging chamber for accelerated UV aging treatment. Aging conditions were set as follows: using a UV-A 340nm light source, at a blackboard temperature of 60℃, alternating between 8 hours of UV irradiation and 4 hours of condensation, for a total aging time of 500 hours. Before the aging experiment began, the tensile elongation at break of the tarpaulin sample was tested as baseline data. After 500 hours of aging, the tensile elongation at break was tested again, and the elongation retention rate was calculated accordingly. Folding durability test: Before testing, the tarpaulin is cut to a size that matches the fixture, ensuring no edges or defects in the clamping area. The sample is then fixed to the fixture, and a continuous folding experiment is performed according to the radius, folding angle, and cycle frequency set by the equipment. During the test, cracks, holes, and other damage phenomena on the sample surface are observed and recorded in real time. The number of cycles at which obvious damage first appears is taken as the folding durability test. To ensure data reliability, at least three samples are tested in each experiment, and the average and standard deviation are taken. Impact performance test: The prepared tarpaulin was cut into 80×10×4mm (length×width×thickness) notched impact test specimens, and a V-shaped notch was machined in the center of each specimen. Before testing, the specimens were conditioned and equilibrated at 23℃ and -20℃ for 24 hours each. Subsequently, the specimens were fixed on the support of the impact testing machine, and a pendulum impacted the notched area with a specified energy. The impact energy consumed at specimen fracture was recorded. Test results are expressed in KJ / m². 2 This indicates that each group should contain no fewer than 5 samples, and the average value and standard deviation should be taken. For low-temperature impact testing, the samples must be quickly transferred from the low-temperature bath to the testing machine to ensure that the temperature is maintained at -20℃±1℃ during impact. Tensile property test: The tarpaulin was cut into dumbbell-shaped specimens of 150mm×25mm and placed in a -20℃ constant temperature chamber for equilibration for 24 hours. During the test, an electronic universal tensile tester was used to unidirectionally stretch the specimens at a constant tensile speed of 50mm / min under a temperature-controlled environment of -20℃ until fracture. The elongation at fracture (i.e., tensile elongation at break) was recorded. The test results are expressed as a percentage, reflecting the material's fracture elongation ability under low temperature conditions. Each test group consisted of no less than 5 specimens, and the average value was taken as the final result. At the same time, the fracture morphology was recorded to analyze the brittle or tough fracture characteristics of the material. Table 4: Performance indicators of the finished tarpaulins prepared in Examples 10-14 As shown in Table 4, in Examples 10-12, as the proportion of HPP-T resin granules increases, especially at low temperatures (-20°C), the impact strength of HPP-T resin is significantly improved because it contains a rubber phase, which can absorb impact energy and passivate cracks.

[0065] Furthermore, with the increase in the proportion of HPP-T resin granules, the tensile elongation at break at -20℃ also increased, indicating that the low-temperature flexibility of the material was improved. Meanwhile, with the increase in the proportion of HPP-T resin granules, the cold cracking temperature decreases (the absolute value increases, from -25℃ to -27℃), low-temperature embrittlement is delayed, and the material is more cold-resistant; The number of repeated folding durability cycles increases with the increase of HPP-T resin granule proportion. The rubber phase in HPP-T resin granules forms a dispersed phase in the rigid polypropylene matrix. When the material is bent or folded, the rubber phase can deform locally and absorb local stress, thereby preventing the initiation and propagation of cracks. Furthermore, the folding process creates areas of high stress concentration on the surface of the tarpaulin. The high elasticity of the rubber phase can disperse these stresses, reduce the risk of matrix breakage, and thus improve the flexibility and folding resistance of the tarpaulin. Furthermore, as the proportion of HPP-T resin granules increased, the elongation retention rate decreased slightly, but it was still within a reasonable range, indicating that the weather resistance of the tarpaulin was only slightly affected. In other words, increasing the proportion of HPP-T resin granules can improve the low-temperature toughness and folding resistance of tarpaulins, but it will reduce the weather resistance (elongation retention) of tarpaulins.

[0066] According to Table 4, Examples 10, 13 and 14, as the proportion of HPP-S resin granules increases, the Charpy-notched impact strength (23℃ and -20℃) and the number of repeated folding durability decrease. This is mainly because HPP-S resin granules are highly crystalline homopolymer polypropylene, which mainly provides rigidity and weather resistance. However, the crystalline regions have high rigidity and poor flexural toughness, making them prone to brittle fracture at low temperatures. The rubber ratio is insufficient to effectively absorb energy, which is not conducive to repeated folding durability. At the same time, its elongation at break at -20℃ also decreases, increasing the risk of low-temperature embrittlement of the tarpaulin. Furthermore, as the proportion of HPP-S resin granules increases, the cold cracking temperature rises, indicating that the material's resistance to low-temperature brittleness decreases. Furthermore, the elongation retention rate was also improved, indicating that the weather resistance retention ability slightly improves with increasing crystallinity.

[0067] In summary, increasing the proportion of HPP-S resin granules mainly improves weather resistance and rigidity (increased elongation retention), but sacrifices low-temperature impact toughness and flexural strength. Based on the above embodiments 10-14, embodiment 12 was selected as the optimal embodiment, and the following embodiments and comparative examples were designed to further demonstrate that HPP-T resin granules and TPO / SEBS reduce the impact on the finished tarpaulin. Example 15: The preparation method of Example 12 was used, except that 12 parts by weight of TPO / SEBS elastomer composite particles were used, and the TPO content in the TPO / SEBS elastomer composite particles was maintained at 40 wt% and the SEBS content at 60 wt%. Example 16: The preparation method of Example 12 was used, except that 14 parts by weight of TPO / SEBS elastomer composite particles were used, and the TPO content in the TPO / SEBS elastomer composite particles was kept at 40 wt% and the SEBS content was kept at 60 wt%.

[0068] Comparative Example 6: The preparation method of Example 15 was used, except that HPP-T resin granules were not added.

[0069] Comparative Example 7: The preparation method of Example 15 was used, except that: 12 parts by weight of TPO / SEBS elastomer composite particles were used, and the TPO content was 50 wt% and the SEBS content was 50 wt%; Comparative Example 8: The preparation method of Example 15 was used, except that 12 parts by weight of TPO / SEBS elastomer composite particles were used, and the TPO content was 60 wt% and the SEBS content was 40 wt%.

[0070] Table 5: Performance indicators of the finished tarpaulins prepared in Examples 12 and 15-16 As shown in Table 5, under the same process conditions as in Example 12, simply increasing the amount of TPO / SEBS elastomer composite particles to 12 parts by weight and 14 parts by weight (Examples 15 and 16) resulted in a monotonic increase in the low-temperature performance and folding durability of the prepared tarpaulin (Charpy-notched impact strength at -20°C increased from 8.0 KJ / m). 2 Increased to 8.4 KJ / m 2 The tensile elongation at break was increased from 24% to 28%; the cold cracking temperature was reduced from -27°C to -32°C; and the Gelbo folding durability was increased from 5,400 cycles to a maximum of 7,400 cycles.

[0071] The above results indicate that moderately increasing the amount of TPO / SEBS (in the range of 10-14 parts by weight) can significantly enhance the low-temperature flexibility and durability of the tarpaulin. This is because SEBS is a saturated block copolymer with a low risk of low-temperature glass transition. It works synergistically with TPO to form a more continuous soft phase network, resulting in more efficient stress dissipation during folding / bending.

[0072] Based on the above Examples 10 and 15-16, Example 15 was selected as the optimal example, and the effects of HPP-T resin granules and TPO / SEBS elastomer composite granules on the finished tarpaulin were further demonstrated through Comparative Examples 6-8, and illustrated by the following data. Table 6: Performance indicators of the finished tarpaulins prepared in Example 15 and Comparative Examples 6-8 As shown in Table 5, the absence of HPP-T resin granules (Comparative Example 6) leads to a significant decrease in various performance indicators of the finished tarpaulin (compared to Example 15). The reason for this is as follows: HPP-T provides an endogenous rubber phase that forms a micro-dispersed elastic phase in the rigid HPP-S matrix. It is firmly bonded to the matrix and can very effectively initiate and terminate crazes, absorb impact energy, and induce large-scale plastic deformation, thereby greatly improving impact toughness and elongation at break. If the rubber phase is missing, the toughening effect will be reduced. The cold resistance is better than pure PP (about -10℃ to -5℃) but worse than the complete formulation (Example 15). This makes it impossible for the finished tarpaulin to transfer and dissipate stress when impacted or folded. It can be seen that HPP-T resin granules play a key role in improving room temperature / low temperature impact toughness and repeated folding durability. The role of the endogenous rubber phase provided by HPP-T resin granules cannot be completely replaced by externally physically blended elastomers.

[0073] Meanwhile, according to Example 15 and Comparative Example 7, when the TPO content and SEBS content in the TPO / SEBS elastomer composite particles are adjusted to 50wt% and 50wt% respectively, since SEBS is used to provide a lower temperature rubber segment and better elastic recovery, low temperature flexibility and flexural strength, when the SEBS content is reduced to 50wt%, the low temperature toughness and flexural life will be slightly reduced, but the room temperature impact or processing compatibility may be slightly improved. Correspondingly, the increase in TPO content can improve the overall fracture strength and processing uniformity of the material.

[0074] According to Example 15 and Comparative Example 8, and in conjunction with the data in Table 5, when the TPO content in the TPO / SEBS elastomer composite particles is further reduced, the Charpy-notched impact strength, tensile elongation at break, cold cracking temperature (significantly worse cold resistance), and repeated folding durability at -20℃ are further reduced. The reason for this is that SEBS and the endogenous rubber phase of HPP-T together form discrete and uniformly distributed soft phase microdomains (micrometer / submicrometer scale), which effectively dissipate energy in the matrix. When the SEBS content is too high, the soft phase evolves from a discrete phase into a partially continuous phase or a large-scale interconnected phase, resulting in the destruction of the continuity of the matrix (rigid phase). When the proportion of SEBS in the elastomer system is too high (while the proportion of TPO is too low), the system will transform from discrete micro-domains to soft phase partial connectivity / aggregation, and the phase interface area will increase while the original PP-g-MAH compatibility dose is insufficient to maintain a high-quality interface.

[0075] Therefore, the comparative examples 7-8 above demonstrate that in PO / SEBS elastomers, when the TPO:SEBS ratio is adjusted from 40:60 to 50:50 or 60:40, the -20℃ Charpy-notched impact strength, -20℃ elongation at break, cold cracking temperature, and repeated folding durability decrease in that order, proving the dominant role of SEBS in low-temperature toughness and folding durability.

[0076] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A weather-resistant HPP composite tarpaulin, characterized in that, It includes the following components: HPP-S resin granules, HPP-T resin granules, TPO / SEBS elastomer composite granules, HALS light stabilizer, downstream antioxidant, talc, and PP-g-MAH compatibilizer; HPP-S resin granules are obtained by using isotactic polypropylene as the matrix resin and introducing DMDBS nucleating agent and HPP antioxidant for modification. HPP-T resin granules are obtained by polymerizing propylene in a Ziegler-Natta catalytic system, and then sequentially introducing ethylene and propylene monomers, followed by modification with HPP antioxidants. TPO / SEBS elastomer composite particles are obtained by mixing TPO and SEBS in a certain proportion, with TPO content ranging from 40wt% to 60wt% and SEBS content ranging from 40wt% to 60wt%.

2. The weather-resistant HPP composite tarpaulin according to claim 1, characterized in that, The specific steps for preparing the HPP-S resin granules are as follows: Take 96-99 parts by weight of isotactic polypropylene, 0.05-0.12 parts by weight of DMDBS nucleating agent and HPP antioxidant, respectively; Isotactic polypropylene, nucleating agent, and HPP antioxidant are added to a twin-screw melt-mixing extruder and melt-blended at a temperature of 180-220℃, with the shear rate controlled at 50-200 s. -1 ; The mixture is extruded and granulated, then cooled to form granules, to obtain HPP-S resin granules.

3. The weather-resistant HPP composite tarpaulin according to claim 2, characterized in that, The particle size of the HPP-S resin granules is 3-6 mm.

4. The weather-resistant HPP composite tarpaulin according to claim 1, characterized in that, The specific steps for preparing the HPP-T resin granules are as follows: Propylene was polymerized in a loop slurry reactor at 65-75℃ and 3.5-6.0MPa using MgCl2-supported TiCl4 solid catalyst as the main catalyst, triethylaluminum as the co-catalyst, and dicyclopentyldimethoxysilane as the external electron donor for 30-90 min. The molecular weight was adjusted by introducing hydrogen into the reactor to obtain polypropylene powder, which was then subjected to vacuum flash evaporation and nitrogen purging to remove residual monomers and diluents. The aforementioned polypropylene powder was directly fed into a gas-phase fluidized bed reactor. Under conditions of 70-85℃ and 1.5-2.5MPa, ethylene monomer and propylene monomer were sequentially introduced, and polymerization continued under the same catalytic system to form a rubber phase with a particle size of 0.2-0.5μm. In the rubber phase, ethylene accounted for 10wt% of the total mass of the final HPP-T resin granules, and propylene accounted for 2wt% of the total mass of the final HPP-T resin granules. After polymerization, HPP antioxidant is added to the reaction system to remove unreacted monomers, and the mixture is dried and granulated to obtain HPP-T resin granules.

5. The weather-resistant HPP composite tarpaulin according to claim 4, characterized in that, The particle size of the HPP-T resin granules is 1.5-2 mm.

6. The weather-resistant HPP composite tarpaulin according to claim 4, characterized in that, The polypropylene powder has a particle size of 600-800 μm, a porosity of 0.2-0.4, a xylene-soluble content ≤3.0 wt%, and a bulk density of 0.35-0.50 g / cm³. 3 .

7. The method for preparing weather-resistant HPP composite tarpaulin according to claim 2 or 5, characterized in that, The HPP antioxidant is obtained by compounding Irganox 1010 and Irgafos 168, and the mass ratio of Irganox 1010 to Irgafos 168 is 1:

3. In the preparation of HPP-S resin granules, the total amount of HPP antioxidant added accounts for 0.08-0.15 wt% of the total mass of the final HPP-S resin granules; In the preparation of HPP-T resin granules, the total amount of HPP antioxidant added accounts for 0.1-0.3 wt% of the total mass of the final HPP-T resin granules.

8. A method for preparing a weather-resistant HPP composite tarpaulin, used to prepare a weather-resistant HPP composite tarpaulin as described in any one of claims 1-7, characterized in that, Includes the following steps: Weigh the following raw materials: 70-80 parts by weight of HPP-S resin granules, 30-35 parts by weight of HPP-T resin granules, 10-14 parts by weight of TPO / SEBS elastomer composite granules, 0.3-0.6 parts by weight of HALS light stabilizer, 0.12-0.16 parts by weight of downstream antioxidant, 3-5 parts by weight of talc, and 0.5-2.0 parts by weight of PP-g-MAH compatibilizer; HPP-S resin granules and HPP-T resin granules were premixed in a certain proportion, and TPO / SEBS elastomer composite granules, talc powder and PP-g-MAH compatibilizer were added to the premix in sequence. The thoroughly mixed premixed material is added to a twin-screw melt mixing extruder and extruded at a temperature of 200-240℃ for 140-180 seconds. -1 The shear rate was measured, and the melt mixing process lasted 4-6 minutes. Add downstream antioxidants and HALS light stabilizers in the later stage of melt mixing, and stir evenly for 1-3 minutes; The molten mixture is extruded through an extruder die, cooled by air cooling, and cut into composite tarpaulin masterbatch with a particle size of 3-6mm to obtain the final HPP composite granules; HPP composite granules are calendered into a film at a temperature of 200–240℃, and then cooled and wound to obtain the finished tarpaulin.

9. The method for preparing weather-resistant HPP composite tarpaulin according to claim 8, characterized in that, The premixing ratio of HPP-S to HPP-T granules is 2~2.7:

1.

10. The method for preparing weather-resistant HPP composite tarpaulin according to claim 8, characterized in that, The downstream antioxidant is obtained by compounding Irganox 1010 and Irgafos 168, and the mass ratio of Irganox 1010 to Irgafos 168 is 1~1.3:1.

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