Preparation method and application of nucleating aid for anti-reflection polypropylene
By combining sorbitol-based nucleating agents with modified inorganic nanoparticles and employing a medium-to-low temperature melt blending process, the problem of insufficient synergistic improvement in transparency and mechanical properties of polypropylene nucleating agents was solved, achieving good dispersion of inorganic particles and low-energy processing.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-15
- Publication Date
- 2026-04-03
AI Technical Summary
Existing polypropylene nucleating agents are insufficient in synergistically improving transparency and mechanical properties, have poor inorganic particle dispersibility, and require high processing temperatures, leading to increased energy consumption.
A polypropylene nucleating agent for enhancing transparency was prepared by combining sorbitol-based nucleating agents with modified inorganic nanoparticles and spray drying. The surface of the inorganic nanoparticles was modified with silane coupling agents and combined with a medium-low temperature melt blending process.
It significantly improves the compatibility between inorganic particles and polypropylene matrix, reduces haze, increases impact strength and flexural modulus, and reduces processing energy consumption.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of polymer material additives technology, and in particular to a method for preparing and applying a nucleating agent for enhancing the clarity of polypropylene. Background Technology
[0002] Polypropylene is widely used in packaging, medical devices, and daily necessities due to its excellent mechanical properties, chemical stability, and processing performance. However, unmodified polypropylene has high crystallinity and a coarse crystal structure, resulting in high haze and poor transparency in the finished products, which limits its application in high-end transparent products.
[0003] Sorbitol-based nucleating agents are currently the mainstream antireflective nucleating agents for polypropylene, such as the Millad series. They significantly reduce product haze by inducing polypropylene to form fine and uniform crystals. However, when traditional sorbitol nucleating agents are used alone, their improvement on the mechanical properties of polypropylene (such as impact strength and rigidity) is limited. Furthermore, when inorganic particles are used as auxiliary components, their poor compatibility with the polypropylene matrix can easily lead to uneven dispersion, which in turn affects the performance of the product. In addition, some nucleating agents require high processing temperatures, increasing energy consumption and processing difficulty.
[0004] Therefore, based on the relevant technologies mentioned above, there is an urgent need to develop a preparation method and application for a nucleating agent for enhancing the clarity of polypropylene. Summary of the Invention
[0005] In view of this, the purpose of this invention is to propose a preparation method and application of a nucleating agent for improving the transparency of polypropylene, so as to solve the problems of insufficient synergistic improvement of transparency and mechanical properties, poor dispersion of inorganic particles, and high processing temperature in the existing polypropylene nucleating agents.
[0006] To achieve the above objectives, the present invention provides a method for preparing and applying a nucleating agent for enhancing the clarity of polypropylene.
[0007] A method for preparing a nucleating agent for enhancing the clarity of polypropylene includes the following steps: Step S1. Add the sorbitol nucleating agent and modified inorganic nanoparticles to a mixer and mix at 60-80℃ for 15-20 min to obtain a mixture. Step S2. Feed the mixture into a spray dryer, control the inlet air temperature to be 120-140℃, the outlet air temperature to be 60-80℃, and the feed rate to be 10-15mL / min. After drying, a nucleating agent for enhancing the transparency of polypropylene is obtained.
[0008] Preferably, the mass ratio of sorbitol nucleating agent to modified inorganic nanoparticles in step S1 is 3-5:1. If the proportion of modified inorganic particles is too high, uneven mixing may occur due to density differences. If the proportion is too low, the mechanical properties will not be sufficiently improved.
[0009] Preferably, the speed of the mixer in step S1 is 800-1000 r / min.
[0010] Preferably, the heating rate during mixing in step S1 is 5°C / min to avoid local overheating.
[0011] Preferably, the sorbitol nucleating agent in step S1 is either 1,3-dibenzylsorbitol or 2,4-dibenzylsorbitol, and the benzylidene group in its molecular structure can form hydrogen bonds with the polypropylene molecular chain to induce crystallization.
[0012] Preferably, the purity of the 1,3-dibenzyl sorbitol is ≥99%, and the purity of the 2,4-dibenzyl sorbitol is ≥99%.
[0013] The reason for controlling the air inlet temperature at 120-140℃ in step S2 is that if the temperature is too low, the drying will be insufficient and the material will clump together, while if the temperature is too high, the sorbitol nucleating agent will soften and agglomerate.
[0014] The reason for setting the outlet air temperature to 60-80℃ in step S2 is to ensure that the moisture content is ≤0.5%, and the feed rate is controlled at 10-15mL / min to match the rotation speed of the atomizing disc and ensure that the droplet size is 50-100μm.
[0015] Preferably, the preparation process of the modified inorganic nanoparticles is as follows: The inorganic nanoparticle composite was added to a high-speed mixer at 1200 r / min and stirred at 80-100℃ for 10-15 min to preheat and activate the particle surface. Then, a silane coupling agent was added dropwise at a rate of 0.5-1 mL / min to avoid excessive local concentration that could lead to self-polymerization of the coupling agent. Stirring was continued for 20-30 min to obtain the modified inorganic nanoparticles.
[0016] Preferably, the mass ratio of the inorganic nanoparticle compound to the silane coupling agent is 90-100:2-5. If the amount of inorganic nanoparticles is too low, it will lead to insufficient modification and insufficient oleophilicity. If the amount is too high, the coupling agent will remain on the particle surface, which will reduce the transparency.
[0017] Preferably, the inorganic nanoparticle composite is obtained by mixing nano-talc, nano-calcium carbonate, and nano-silica in a mass ratio of 2-3:2-4:1.
[0018] Preferably, the nano-talc powder has a particle size of 50-100 nm, the nano-calcium carbonate has a particle size of 30-80 nm, and the nano-silica has a particle size of 20-50 nm.
[0019] Nano-talc has a flake-like structure, which can enhance the rigidity of polypropylene. Nano-calcium carbonate has a spherical structure, which can improve the impact strength of polypropylene. Nano-silica has the smallest particle size and can fill the gaps between nano-talc and nano-calcium carbonate, reducing agglomeration. The ratio of the three can achieve the best synergistic effect. If the proportion of nano-talc is too high, the final product is prone to "whiteness" and increased haze. If the proportion of nano-calcium carbonate is too high, the dispersion difficulty will increase.
[0020] Preferably, the silane coupling agent is γ-aminopropyltriethoxysilane.
[0021] An application of a nucleating agent for enhancing the clarity of polypropylene includes the following steps: A nucleating agent for enhancing the transparency of polypropylene is added to polypropylene resin, melt-blended in a twin-screw extruder, and then granulated and injection molded to obtain polypropylene products.
[0022] Preferably, the mass ratio of the polypropylene nucleating agent to the polypropylene resin is 0.2-0.5:100.
[0023] Preferably, the processing temperature for the melt blending is 180-200℃.
[0024] Preferably, the polypropylene resin is a homopolymer polypropylene with a melt index of 2.5-3.0 g / 10 min, and the screw length-to-diameter ratio of the twin-screw extruder is 36:1.
[0025] Preferably, the specific processing parameters of the twin-screw extruder are as follows: The feeding section temperature is 160-170℃, the compression section temperature is 170-180℃, and the homogenization section temperature is 180-200℃, which is 20-30℃ lower than the traditional processing temperature. The screw speed is 300-350r / min, the vacuum degree is -0.08MPa, volatile matter is removed, the pellet length is 3-4mm, and after granulation, it is injection molded into a sample with a thickness of 1mm. The injection molding temperature of the injection molding machine is 180-190℃, and the holding pressure is 50-60MPa.
[0026] The beneficial effects of this invention are: This invention provides a method for preparing and applying a nucleating agent for enhancing the clarity of polypropylene. The inorganic nanoparticles provided in this invention, after being modified with a silane coupling agent, exhibit improved surface oleophilicity and significantly improved compatibility with the polypropylene matrix and sorbitol nucleating agent, thus solving the problem of poor dispersibility. The sorbitol nucleating agent and inorganic nanoparticle composite system provided by this invention have a synergistic effect. Compared with a single nucleating agent, it can reduce the haze of polypropylene products, increase the impact strength, and increase the flexural modulus. The composite nucleating agent provided by this invention can function stably at 180-200℃, which reduces the processing temperature and energy consumption compared to traditional nucleating agents, and has broad application prospects. Detailed Implementation
[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.
[0028] Example 1: A method for preparing a nucleating agent for enhancing the clarity of polypropylene, comprising the following steps: S1. Mix 200g of nano-talc powder with a particle size of 50-100nm, 200g of nano-calcium carbonate with a particle size of 30-80nm, and 100g of nano-silica with a particle size of 20-50nm to obtain an inorganic nanoparticle composite. The nano-talc powder has a plate-like structure, which can enhance the rigidity of polypropylene. The nano-calcium carbonate has a spherical structure, which can improve the impact strength of polypropylene. The nano-silica has the smallest particle size and can fill the gaps between the nano-talc powder and nano-calcium carbonate, reducing agglomeration. The ratio of the three can achieve the best synergistic effect. If the proportion of nano-talc powder is too high, the final product is prone to "whiteness" and the haze will increase. If the proportion of nano-calcium carbonate is too high, the dispersion difficulty will increase. S2. Add 90g of the inorganic nanoparticle compound to a high-speed mixer at 1200r / min and stir at 80℃ for 10min to preheat and activate the particle surface. Then, add 2g of γ-aminopropyltriethoxysilane at a uniform drop rate of 0.5mL / min to avoid excessive local concentration that could lead to self-polymerization of the coupling agent. Continue stirring for 20min to obtain modified inorganic nanoparticles. If the amount of inorganic nanoparticles is too low, the modification will be insufficient and the lipophilicity will be inadequate. If the amount is too high, the coupling agent will remain on the particle surface, which will reduce the transparency. S3. Add 30g of 1,3-dibenzylsorbitol and 10g of modified inorganic nanoparticles to a mixer at a speed of 800r / min, heat to 60℃ at a heating rate of 5℃ / min, and mix at 60℃ for 15min to obtain a mixture. The benzylidene group in the molecular structure of 1,3-dibenzylsorbitol can form hydrogen bonds with the polypropylene molecular chain to induce crystallization. The purity of 1,3-dibenzylsorbitol is ≥99%, and the purity of 2,4-dibenzylsorbitol is ≥99%. S4. Feed the mixture into a spray dryer, controlling the inlet air temperature at 120℃, the outlet air temperature at 60℃, and the feed rate at 10mL / min. After drying, a nucleating agent for enhancing the transparency of polypropylene is obtained. The reason for controlling the inlet air temperature at 120℃ is that if the temperature is too low, the drying will be insufficient and the material will clump together. If the temperature is too high, the sorbitol nucleating agent will soften and agglomerate. The reason for controlling the outlet air temperature at 60℃ is to ensure that the moisture content is ≤0.5%. The feed rate is controlled at 10mL / min to match the rotation speed of the atomizing disc and ensure that the droplet size is 50-100μm.
[0029] Example 2: A method for preparing a nucleating agent for enhancing the clarity of polypropylene, comprising the following steps: S1. Mix 250g of nano-talc powder with a particle size of 50-100nm, 300g of nano-calcium carbonate with a particle size of 30-80nm, and 100g of nano-silica with a particle size of 20-50nm to obtain an inorganic nanoparticle composite. The nano-talc powder has a plate-like structure, which can enhance the rigidity of polypropylene. The nano-calcium carbonate has a spherical structure, which can improve the impact strength of polypropylene. The nano-silica has the smallest particle size and can fill the gaps between the nano-talc powder and nano-calcium carbonate, reducing agglomeration. The ratio of the three can achieve the best synergistic effect. If the proportion of nano-talc powder is too high, the final product is prone to "whiteness" and the haze will increase. If the proportion of nano-calcium carbonate is too high, the dispersion difficulty will increase. S2. Add 95g of the inorganic nanoparticle compound to a high-speed mixer at 1200r / min and stir at 90℃ for 13min. Preheating activates the particle surface. Then, add 3.5g of γ-aminopropyltriethoxysilane at a uniform drop rate of 0.75mL / min to avoid excessive local concentration that could lead to self-polymerization of the coupling agent. Continue stirring for 25min to obtain modified inorganic nanoparticles. If the amount of inorganic nanoparticles is too low, the modification will be insufficient and the lipophilicity will be inadequate. If the amount is too high, the coupling agent will remain on the particle surface, which will reduce the transparency. S3. Add 40g of 2,4-dibenzylsorbitol and 10g of modified inorganic nanoparticles to a mixer at a speed of 900r / min, heat to 70℃ at a heating rate of 5℃ / min, and mix at 70℃ for 18min to obtain a mixture. The benzylidene group in the molecular structure of 2,4-dibenzylsorbitol can form hydrogen bonds with the polypropylene molecular chain to induce crystallization. The purity of 1,3-dibenzylsorbitol is ≥99%, and the purity of 2,4-dibenzylsorbitol is ≥99%. S4. Feed the mixture into a spray dryer, controlling the inlet air temperature at 130℃, the outlet air temperature at 70℃, and the feed rate at 13mL / min. After drying, a nucleating agent for enhancing the transparency of polypropylene is obtained. The reason for controlling the inlet air temperature at 130℃ is that if the temperature is too low, the drying will be insufficient and the material will clump together. If the temperature is too high, the sorbitol nucleating agent will soften and agglomerate. The reason for controlling the outlet air temperature at 70℃ is to ensure that the moisture content is ≤0.5%. The feed rate is controlled at 13mL / min to match the rotation speed of the atomizing disc and ensure that the droplet size is 50-100μm.
[0030] Example 3: A method for preparing a nucleating agent for enhancing the clarity of polypropylene, comprising the following steps: S1. Mix 280g of nano-talc powder with a particle size of 50-100nm, 350g of nano-calcium carbonate with a particle size of 30-80nm, and 100g of nano-silica with a particle size of 20-50nm to obtain an inorganic nanoparticle composite. The nano-talc powder has a plate-like structure, which can enhance the rigidity of polypropylene. The nano-calcium carbonate has a spherical structure, which can improve the impact strength of polypropylene. The nano-silica has the smallest particle size and can fill the gaps between the nano-talc powder and nano-calcium carbonate, reducing agglomeration. The ratio of the three can achieve the best synergistic effect. If the proportion of nano-talc powder is too high, the final product is prone to "whiteness" leading to increased haze. If the proportion of nano-calcium carbonate is too high, the dispersion difficulty will increase. S2. Add 98g of the inorganic nanoparticle compound to a high-speed mixer at 1200r / min and stir at 95℃ for 10-13-15min. Preheating activates the particle surface. Then, add 4g of γ-aminopropyltriethoxysilane dropwise at a rate of 0.85mL / min to avoid excessive local concentration that could lead to self-polymerization of the coupling agent. Continue stirring for 28min to obtain modified inorganic nanoparticles. If the amount of inorganic nanoparticles is too low, the modification will be insufficient and the lipophilicity will be inadequate. If the amount is too high, the coupling agent will remain on the particle surface, which will reduce the transparency. S3. Add 45g of 2,4-dibenzylsorbitol and 10g of modified inorganic nanoparticles to a mixer at a speed of 950r / min, heat to 75℃ at a heating rate of 5℃ / min, and mix at 75℃ for 19min to obtain a mixture. The benzylidene group in the molecular structure of 2,4-dibenzylsorbitol can form hydrogen bonds with the polypropylene molecular chain to induce crystallization. The purity of 1,3-dibenzylsorbitol is ≥99%, and the purity of 2,4-dibenzylsorbitol is ≥99%. S4. Feed the mixture into a spray dryer, controlling the inlet air temperature at 135℃, the outlet air temperature at 75℃, and the feed rate at 14mL / min. After drying, a nucleating agent for enhancing the transparency of polypropylene is obtained. The reason for controlling the inlet air temperature at 135℃ is that if the temperature is too low, the drying will be insufficient and the material will clump together. If the temperature is too high, the sorbitol nucleating agent will soften and agglomerate. The reason for controlling the outlet air temperature at 75℃ is to ensure that the moisture content is ≤0.5%. The feed rate is controlled at 14mL / min to match the rotation speed of the atomizing disc and ensure that the droplet size is 50-100μm.
[0031] Example 4: A method for preparing a nucleating agent for enhancing the clarity of polypropylene, comprising the following steps: S1. Mix 300g of nano-talc powder with a particle size of 50-100nm, 400g of nano-calcium carbonate with a particle size of 30-80nm, and 100g of nano-silica with a particle size of 20-50nm to obtain an inorganic nanoparticle composite. The nano-talc powder has a plate-like structure, which can enhance the rigidity of polypropylene. The nano-calcium carbonate has a spherical structure, which can improve the impact strength of polypropylene. The nano-silica has the smallest particle size and can fill the gaps between the nano-talc powder and nano-calcium carbonate, reducing agglomeration. The ratio of the three can achieve the best synergistic effect. If the proportion of nano-talc powder is too high, the final product is prone to "whiteness" and the haze will increase. If the proportion of nano-calcium carbonate is too high, the dispersion difficulty will increase. S2. Add 100g of inorganic nanoparticle compound to a high-speed mixer at 1200r / min and stir at 100℃ for 15min to preheat and activate the particle surface. Then, add 5g of γ-aminopropyltriethoxysilane at a uniform drop rate of 1mL / min to avoid excessive local concentration that could lead to self-polymerization of the coupling agent. Continue stirring for 30min to obtain modified inorganic nanoparticles. If the amount of inorganic nanoparticles is too low, the modification will be insufficient and the lipophilicity will be inadequate. If the amount is too high, the coupling agent will remain on the particle surface, which will reduce the transparency. S3. Add 50g of 1,3-dibenzylsorbitol and 10g of modified inorganic nanoparticles to a mixer at a speed of 1000r / min and heat to 80℃ at a heating rate of 5℃ / min. Mix at 80℃ for 20min to obtain a mixture. The benzylidene group in the molecular structure of 1,3-dibenzylsorbitol can form hydrogen bonds with the polypropylene molecular chain to induce crystallization. The purity of 1,3-dibenzylsorbitol is ≥99%, and the purity of 2,4-dibenzylsorbitol is ≥99%. S4. Feed the mixture into a spray dryer, controlling the inlet air temperature at 140℃, the outlet air temperature at 80℃, and the feed rate at 15mL / min. After drying, a nucleating agent for enhancing the transparency of polypropylene is obtained. The reason for controlling the inlet air temperature at 140℃ is that if the temperature is too low, the drying will be insufficient and the material will clump together. If the temperature is too high, the sorbitol nucleating agent will soften and agglomerate. The reason for controlling the outlet air temperature at 80℃ is to ensure that the moisture content is ≤0.5%. The feed rate is controlled at 15mL / min to match the rotation speed of the atomizing disc and ensure that the droplet size is 50-100μm.
[0032] Example 5: An application of a nucleating agent for enhancing the clarity of polypropylene, comprising the following steps: 0.2g of the polypropylene nucleating agent prepared in Example 1 was added to 100g of homopolymer polypropylene with a melt index of 2.5g / 10min. The mixture was melt-blended in a twin-screw extruder at 180°C. After granulation and injection molding, polypropylene products were obtained. The twin-screw extruder had a screw length-to-diameter ratio of 36:1. The specific processing parameters of the twin-screw extruder were as follows: feeding section temperature of 160°C, compression section temperature of 170°C, and homogenization section temperature of 180°C, which is 20-30°C lower than the traditional processing temperature. The screw speed was 300r / min, the vacuum degree was -0.08MPa, volatile matter was removed, and the pellet length was 3-4mm. After granulation, the pellets were injection molded into 1mm thick samples. The injection molding temperature was 180°C and the holding pressure was 50MPa.
[0033] Example 6: An application of a nucleating agent for antireflective polypropylene, comprising the following steps: 0.35g of the polypropylene nucleating agent prepared in Example 2 was added to 100g of homopolymer polypropylene with a melt index of 2.7g / 10min. The mixture was melt-blended in a twin-screw extruder at 190°C. After granulation and injection molding, polypropylene products were obtained. The twin-screw extruder had a screw length-to-diameter ratio of 36:1. The specific processing parameters of the twin-screw extruder were as follows: feeding section temperature of 165°C, compression section temperature of 175°C, and homogenization section temperature of 190°C, which is 20-30°C lower than the traditional processing temperature. The screw speed was 325r / min, the vacuum degree was -0.08MPa, volatile matter was removed, and the pellet length was 3-4mm. After granulation, the pellets were injection molded into 1mm thick strips. The injection molding temperature was 185°C and the holding pressure was 55MPa.
[0034] Example 7: An application of a nucleating agent for enhancing the clarity of polypropylene, comprising the following steps: 0.4g of the polypropylene nucleating agent prepared in Example 3 was added to 100g of homopolymer polypropylene with a melt index of 2.8g / 10min. The mixture was melt-blended in a twin-screw extruder at 195°C. After granulation and injection molding, polypropylene products were obtained. The twin-screw extruder had a screw length-to-diameter ratio of 36:1. The specific processing parameters of the twin-screw extruder were as follows: feeding section temperature of 168°C, compression section temperature of 178°C, and homogenization section temperature of 195°C, which is 20-30°C lower than the traditional processing temperature. The screw speed was 340r / min, the vacuum degree was -0.08MPa, volatile matter was removed, and the pellet length was 3-4mm. After granulation, the pellets were injection molded into 1mm thick samples. The injection molding temperature was 188°C and the holding pressure was 58MPa.
[0035] Example 8: An application of a nucleating agent for enhancing the clarity of polypropylene, comprising the following steps: 0.5g of the polypropylene nucleating agent prepared in Example 4 was added to 100g of homopolymer polypropylene with a melt index of 3.0g / 10min. The mixture was melt-blended in a twin-screw extruder at 200℃. After granulation and injection molding, polypropylene products were obtained. The twin-screw extruder had a screw length-to-diameter ratio of 36:1. The specific processing parameters of the twin-screw extruder were as follows: feeding section temperature of 160-165-170℃, compression section temperature of 180℃, and homogenization section temperature of 200℃, which is 20-30℃ lower than the traditional processing temperature. The screw speed was 350r / min, the vacuum degree was -0.08MPa, volatile matter was removed, and the pellet length was 3-4mm. After granulation, the pellets were injection molded into 1mm thick samples. The injection molding temperature was 190℃ and the holding pressure was 60MPa.
[0036] Comparative Example 1: Compared with Example 1, this comparative example only omits the addition of γ-aminopropyltriethoxysilane. Instead, it directly uses the unmodified inorganic nanoparticle complex, i.e., only nano-talc, nano-calcium carbonate, nano-silica, and sorbitol nucleating agent are mixed. The addition and stirring of silane coupling agent are omitted, and the inorganic nanoparticle complex is directly mixed with 1,3-dibenzylsorbitol. All other steps and parameters are the same, and will not be repeated in this comparative example. The final result is a nucleating agent for enhancing the clarity of polypropylene.
[0037] Comparative Example 2: Compared with Example 1, this comparative example only replaces "inorganic nanoparticle compound" with "single nano talc powder". All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, a nucleating agent for improving the transparency of polypropylene is obtained.
[0038] Comparative Example 3: Compared with Example 1, this comparative example did not add inorganic nanoparticle complex, but only used 1,3-dibenzylsorbitol as nucleating agent. The remaining steps and parameters were the same, and will not be repeated in this comparative example. Finally, a nucleating agent for improving the transparency of polypropylene was obtained.
[0039] Comparative Example 4: Compared with Example 1, this comparative example only changed the inorganic nanoparticle compounding ratio to "400g of nano talc, 100g of nano calcium carbonate, and 100g of nano silica", which deviates from the patented ratio of 2-3:2-4:1. The proportion of talc is too high. The other steps and parameters are the same, and this comparative example will not repeat them. Finally, a nucleating agent for enhancing the transparency of polypropylene is obtained.
[0040] Comparative Example 5: Compared with Example 1, this comparative example only replaces the low-temperature process of melt blending in this invention with conventional high-temperature processing. When applied, the temperature of the homogenization section of the twin-screw extruder is increased to 220°C (the conventional processing temperature, which is higher than the 180°C of this invention). All other application parameters remain unchanged.
[0041] Comparative Example 6: Compared with Example 1, this comparative example only replaces "γ-aminopropyltriethoxysilane" with "methyltrimethoxysilane". Without the modification of the lipophilic group, the modification effect is poor. The other steps and parameters are the same, and will not be repeated in this comparative example. Finally, a nucleating agent for improving the transparency of polypropylene is obtained.
[0042] Comparative Example 7: Compared with Example 5, this comparative example only replaces "nucleating agent for antireflective polypropylene prepared in Example 1" with "nucleating agent for antireflective polypropylene prepared in Comparative Example 1". All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, a polypropylene product is obtained.
[0043] Comparative Example 8: Compared with Example 5, this comparative example only replaces "nucleating agent for antireflective polypropylene prepared in Example 1" with "nucleating agent for antireflective polypropylene prepared in Comparative Example 2". All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, a polypropylene product is obtained.
[0044] Comparative Example 9: Compared with Example 5, this comparative example only replaces "nucleating agent for antireflective polypropylene prepared in Example 1" with "nucleating agent for antireflective polypropylene prepared in Comparative Example 3". All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, a polypropylene product is obtained.
[0045] Comparative Example 10: Compared with Example 5, this comparative example only replaces "nucleating agent for antireflective polypropylene prepared in Example 1" with "nucleating agent for antireflective polypropylene prepared in Comparative Example 4". All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, a polypropylene product is obtained.
[0046] Comparative Example 11: Compared with Example 5, this comparative example only replaces "nucleating agent for antireflective polypropylene prepared in Example 1" with "nucleating agent for antireflective polypropylene prepared in Comparative Example 5". All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, a polypropylene product is obtained.
[0047] Comparative Example 12: Compared with Example 5, this comparative example only replaces "nucleating agent for antireflective polypropylene prepared in Example 1" with "nucleating agent for antireflective polypropylene prepared in Comparative Example 6". All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, a polypropylene product is obtained.
[0048] Performance testing: The samples prepared in Examples 1-4 and Comparative Examples 1-6 were used to prepare polypropylene products, and all the obtained polypropylene products were injection molded into 1 mm thick strips, which were then tested after standing for 24 hours. The details are shown in Tables 1-X below: Table 1 Test Standards and Equipment Table 2 Summary of Test Data Table 3 Summary of Test Data Table 4 Summary of Test Data In Comparative Example 5, the nucleating agent was prepared without high temperature, but the original design required high-temperature processing. Here, the same conditions were used for testing. The change in melt flow rate was not due to any problem with the nucleating agent itself, but mainly reflected the effect of processing on the resin.
[0049] Performance pattern analysis of Examples 1-4: Relationship between transparency and addition amount: As the addition amount of nucleating agent increased from 0.2% to 0.5% (Examples 1→4), the haze decreased from 18.0% to 15.0%, indicating that within the range of 0.2%-0.5%, increasing the addition amount can enhance the nucleation effect (more nucleation sites induce fine spherulites), but the increase gradually slows down (0.5% decreases by only 1.0% compared to 0.4%), proving that this range is the optimal addition range.
[0050] Synergistic improvement in mechanical properties: Impact strength increased from 3.2kJ / m² to 3.6kJ / m², and flexural modulus increased from 1800MPa to 1850MPa. As the amount of modified inorganic particles (talc and calcium carbonate) increased, the synergistic effect of rigidity and toughness became more significant, and the uniform dispersion (agglomerated particle size ≤5μm) did not produce any negative effects.
[0051] Processing stability: The melt flow rate variation was consistently controlled within -3.0% to -4.5%, far lower than the 10%-15% of traditional high-temperature processing, proving that medium-low temperature (180-200℃) processes can effectively reduce polypropylene degradation.
[0052] Table 4 Comparative Analysis of Comparative Example and Example 1 in conclusion: Necessity of the modification process: Comparative Examples 1 and 6 demonstrate that γ-aminopropyltriethoxysilane modification is the core solution to the problem of inorganic particle dispersion (agglomeration particle size reduced from 30μm / 12μm to ≤5μm), which directly affects transparency and mechanical properties.
[0053] Synergistic effect of compound system: Comparative examples 2 and 3 demonstrate that the compound of "sorbitol + nano talc + calcium carbonate + silicon dioxide" is the key to synergistically improving transparency and mechanical properties, and the effect cannot be achieved by a single component or deviation in proportion.
[0054] Reasonableness of process parameters: Examples 1-4 and Comparative Example 5 demonstrate that a processing temperature of 180-200℃ and an addition amount of 0.2%-0.5% are the optimal range for balancing performance and cost, ensuring nucleation effect while reducing resin degradation.
[0055] The test data shows that the present invention achieves a synergistic improvement in the transparency and mechanical properties of polypropylene through the combined design of "inorganic particle modification + specific ratio compounding + medium and low temperature process", and has excellent processing stability. Each technical feature is a necessary condition for performance optimization, which is superior to the existing technical solutions.
[0056] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.
[0057] This invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.
Claims
1. A method for preparing a nucleating agent for enhancing the clarity of polypropylene, characterized in that, Includes the following steps: Step S1. Add the sorbitol nucleating agent and modified inorganic nanoparticles to a mixer and mix at 60-80℃ for 15-20 min to obtain a mixture. Step S2. Feed the mixture into a spray dryer, control the inlet air temperature to be 120-140℃, the outlet air temperature to be 60-80℃, and the feed rate to be 10-15mL / min. After drying, a nucleating agent for enhancing the transparency of polypropylene is obtained.
2. The method for preparing the nucleating agent for enhancing the clarity of polypropylene according to claim 1, characterized in that, The mass ratio of sorbitol-based nucleating agent to modified inorganic nanoparticles in step S1 is 3-5:1; The speed of the mixer mentioned in step S1 is 800-1000 r / min; The heating rate during mixing in step S1 is 5°C / min.
3. The method for preparing the nucleating agent for enhancing the clarity of polypropylene according to claim 1, characterized in that, The sorbitol nucleating agent mentioned in step S1 is either 1,3-dibenzylsorbitol or 2,4-dibenzylsorbitol; The purity of the 1,3-dibenzylidene sorbitol is ≥99%, and the purity of the 2,4-dibenzylidene sorbitol is ≥99%.
4. The method for preparing the nucleating agent for enhancing the clarity of polypropylene according to claim 1, characterized in that, The preparation process of the modified inorganic nanoparticles is as follows: The inorganic nanoparticle composite was added to a high-speed mixer at a speed of 1200 r / min and stirred at 80-100℃ for 10-15 min to preheat and activate the particle surface. Then, a silane coupling agent was added dropwise at a rate of 0.5-1 mL / min and stirring was continued for 20-30 min to obtain modified inorganic nanoparticles.
5. The method for preparing the nucleating agent for enhancing the clarity of polypropylene according to claim 4, characterized in that, The mass ratio of the inorganic nanoparticle composite to the silane coupling agent is 90-100:2-5.
6. The method for preparing the nucleating agent for enhancing the clarity of polypropylene according to claim 4, characterized in that, The inorganic nanoparticle composite is obtained by mixing nano-talc, nano-calcium carbonate, and nano-silica in a mass ratio of 2-3:2-4:
1. The nano-talc powder has a particle size of 50-100nm, the nano-calcium carbonate has a particle size of 30-80nm, and the nano-silica has a particle size of 20-50nm. The silane coupling agent is γ-aminopropyltriethoxysilane.
7. An application of a nucleating agent for enhancing the clarity of polypropylene, characterized in that, Includes the following steps: A nucleating agent for enhancing the transparency of polypropylene is added to polypropylene resin, melt-blended in a twin-screw extruder, and then granulated and injection molded to obtain polypropylene products.
8. The application of the nucleating agent for enhancing the clarity of polypropylene according to claim 7, characterized in that, The mass ratio of the polypropylene nucleating agent and the polypropylene resin used for enhancing transparency is 0.2-0.5:100; The processing temperature for the melt blend is 180-200℃.
9. The application of the nucleating agent for enhancing the clarity of polypropylene according to claim 7, characterized in that, The polypropylene resin is a homopolymer polypropylene with a melt index of 2.5-3.0 g / 10 min, and the screw length-to-diameter ratio of the twin-screw extruder is 36:
1.
10. The application of the nucleating agent for enhancing the clarity of polypropylene according to claim 7, characterized in that, The specific processing parameters of the twin-screw extruder are as follows: The feeding section temperature is 160-170℃, the compression section temperature is 170-180℃, and the homogenization section temperature is 180-200℃; the screw speed is 300-350r / min, the vacuum degree is -0.08MPa, and the pellet length is 3-4mm. After granulation, the pellets are injection molded into 1mm thick strips. The injection molding temperature of the injection molding machine is 180-190℃, and the holding pressure is 50-60MPa.