Weather-resistant anti-aging polypropylene material and preparation method thereof

Abstract

The invention discloses a weather-resistant anti-aging polypropylene material and a preparation method thereof. The weather-resistant and anti-aging polypropylene material is prepared from polypropylene resin, vinyl amino compound grafted polypropylene, modified filler, an ultraviolet light absorber, a hindered amine light stabilizer, an antioxidant and an acid remover, the vinyl amino compound grafted polypropylene is prepared by carrying out free radical copolymerization reaction on polypropylene and a vinyl amino compound in a reaction solvent; the reaction solvent comprises a main solvent and a cosolvent in a mass ratio of 100: (0.5-1.2); the main solvent is selected from xylene or decahydronaphthalene, and the cosolvent is selected from N, N-dimethylformamide or methyl ethyl ketone. The invention aims to improve the compatibility of the weather-resistant auxiliary agent and polypropylene resin, solve the degradation effect of a traditional maleic anhydride grafted polyolefin compatilizer on a polypropylene matrix, and improve the weather resistance and aging resistance of a polypropylene material.

Description

Technical Field

[0001] This application relates to the field of polypropylene materials, and in particular to a weather-resistant and anti-aging polypropylene material and its preparation method. Background Art

[0002] As a thermoplastic plastic with excellent comprehensive properties, polypropylene has been widely used in fields such as packaging, household appliances, and automotive parts due to its good chemical corrosion resistance, easy processability, and cost advantages. However, the tertiary carbon atoms in the polypropylene molecular chain make it extremely sensitive to ultraviolet light and thermo-oxidation. When exposed to light, humidity, and heat in the outdoor environment for a long time, problems such as molecular chain breakage and oxidative degradation are likely to occur, resulting in a decrease in the mechanical strength of the material, surface powdering, and yellowing, which severely restricts its application in scenarios such as outdoor tents, furniture, and building sunshades.

[0003] To improve this defect, the industry usually adopts a weather-resistant additive system such as ultraviolet absorbers, light stabilizers, and compound antioxidants to delay the aging process by absorbing ultraviolet radiation and capturing free radicals. However, most of these additives are small-molecule organic compounds with significant polarity differences from the polypropylene matrix, and are prone to migration and precipitation during processing or use. This not only causes the protective function to decay over time, but also forms foggy precipitates on the material surface, affecting the transparency and appearance quality of the product. Regarding the compatibility problem, the prior art mostly uses compatibilizers such as maleic anhydride grafted polypropylene (MAH-g-PP) as interfacial modifiers to improve the dispersion stability by utilizing the polar interaction between its carboxylic anhydride groups and the additives. However, it is difficult to avoid the residual unreacted anhydride monomers during the maleic anhydride grafting reaction. These acidic substances may catalyze the hydrolysis or oxidation reaction of the polypropylene resin during high-temperature processing or long-term use, instead accelerating the material aging and causing yellowing, forming a "anti-aging - pro-degradation" contradictory effect. In addition, the acid anhydride residue will also undergo a neutralization reaction with the basic groups in the light stabilizer, reducing the activity of the additive and further weakening the durability of the protection system. Summary of the Invention

[0004] This application provides a weather-resistant and anti-aging polypropylene material and its preparation method, which can improve the compatibility between the weather-resistant additives and the polypropylene resin while alleviating the degradation effect of traditional maleic anhydride grafted polyolefin compatibilizers on the polypropylene matrix, and improve the weather-resistant and anti-aging performance of the polypropylene material.

[0005] In the first aspect, this application provides a weather-resistant and anti-aging polypropylene material, which comprises the following raw materials in parts by mass: 100 parts of polypropylene resin, 2 - 5 parts of vinylamino compound grafted polypropylene, 5 - 15 parts of modified filler, 0.3 - 0.8 parts of ultraviolet absorber, 0.2 - 1.0 parts of hindered amine light stabilizer, 0.5 - 1.2 parts of antioxidant, 0.1 - 0.5 parts of acid remover; The vinylamino compound-grafted polypropylene is prepared by free radical copolymerization of polypropylene and a vinylamino compound with a mass ratio of 100:5 to 15 in a reaction solvent at a reaction temperature of 110 to 130 °C; the reaction solvent includes a main solvent and a co-solvent with a mass ratio of 100:0.5 to 1.2; the main solvent is selected from xylene or decalin, and the co-solvent is selected from N,N-dimethylformamide or methyl ethyl ketone.

[0006] In this application, through the free radical copolymerization reaction of a vinylamino compound and polypropylene, an amino functional group is introduced into the polypropylene molecular chain to form an aminated polypropylene compatibilizer. The strong polarity and hydrogen bond-forming ability of the amino group significantly improve its compatibility with ultraviolet absorbers, hindered amine light stabilizers, and antioxidants, effectively inhibiting the migration and precipitation of additives and avoiding the surface precipitation problem caused by the polarity difference of traditional small molecule additives. Compared with the residual carboxylic anhydride monomer in maleic anhydride grafted polypropylene (MAH-g-PP), the amino group of aminated polypropylene can neutralize acidic substances (such as HCl) generated during processing or aging, blocking the catalytic degradation of the polypropylene molecular chain by acidic substances, thereby reducing the risk of aging yellowing and deterioration of strength properties. In addition, the amino group can also coordinate with metal ions such as Zn 2+ released during the processing to form a stable complex, further inhibiting the metal ion-catalyzed degradation reaction.

[0007] In terms of process, this application adopts the solvent free radical copolymerization method, using xylene or decalin as the main solvent and N,N-dimethylformamide (DMF) or methyl ethyl ketone (MEK) as the co-solvent. The main solvent effectively swells the polypropylene chain segments at 100 to 120 °C, promoting the diffusion of monomers into the chain segments; the co-solvent improves the solubility of vinylamino compounds (such as vinylbenzylamine) through polarity matching, avoiding the formation of homopolymers caused by excessive local monomer concentration, thereby increasing the grafting rate. The reaction temperature needs to be controlled at 110 to 130 °C. Too high a temperature will cause β degradation of polypropylene, resulting in molecular chain breakage and deterioration of mechanical properties; too low a temperature is not compatible with the main solvent, resulting in insufficient swelling and difficulty for monomers to penetrate into the polypropylene chain segments, and the grafting rate will decrease significantly, and its role as a compatibilizer in the polypropylene system of this application will decline.

[0008] In any of the above technical solutions, the preparation method of the vinylamino compound-grafted polypropylene includes: Adding polypropylene into the main solvent, stirring evenly, heating to 110 to 130 °C, and stirring to swell the polypropylene to obtain a matrix solution; mixing the vinylamino compound with the co-solvent, adding it to the matrix solution, and stirring for 30 to 60 min; The initiator and the solvent are mixed and stirred to prepare an initiator solution, and the initiator solution is added dropwise to the matrix solution. After the addition is completed, the reaction is carried out for 2 to 4 hours to obtain a reaction solution. After the temperature is lowered to below 60°C, the reaction solution is poured into acetone to precipitate, and the precipitate is washed by immersion in anhydrous ethanol and vacuum dried.

[0009] In any of the above technical solutions, the vinylamine compound is vinylbenzylamine and / or vinylaniline.

[0010] In any of the above technical solutions, the vinylamine compound is vinylbenzylamine and / or vinylaniline in a mass ratio of 2 to 3:1.

[0011] In any of the above technical solutions, the main solvent used to swell the polypropylene is 4 to 6 times the mass of the polypropylene.

[0012] This application adopts a compound system of vinylbenzylamine (VBA) and vinylaniline (VA), taking into account both grafting efficiency and anti-yellowing performance. The conjugation effect of VBA is weak and the free radical addition rate is low. In contrast, the benzene ring conjugation effect of VA can stabilize free radical intermediates, the competitive polymerization rate is higher than that of VBA, and VA has a high grafting rate. However, if VA is used alone, it is easy to form local high-polarity areas due to uneven grafting, and the aniline structure is easily oxidized at high temperatures to generate quinone-type colored substances, which aggravates the yellowing of the material. By compounding VBA and VA, the rapid grafting of VA provides the system with initial active sites, and the flexible amine group of VBA optimizes the long-term stability, which helps to achieve a balance between grafting rate and weathering and anti-aging performance.

[0013] In any of the above technical solutions, the swelling time is 30 to 80 minutes.

[0014] In any of the above technical solutions, the initiator solution is added at a dripping speed of 1 to 3 wt% / min.

[0015] In any of the above technical solutions, the mass concentration of the initiator solution is 10 to 20 wt %.

[0016] In any of the above technical solutions, the amount of the initiator used is 1 to 5 wt % of the polypropylene.

[0017] In any of the above technical solutions, the initiator is dicumyl peroxide, di-tert-butyl peroxide or benzoyl peroxide.

[0018] In this application, through the step-by-step process of pre-swelling the matrix solution and dropwise adding the grafting solution, combined with the promoting effect of the co-solvent on the penetration and diffusion of vinylamine-based compounds, the efficient and controllable grafting reaction is achieved. Specifically, during the swelling stage, polypropylene fully absorbs the main solvent, increasing the molecular chain spacing and providing a channel for the subsequent monomer diffusion. The co-solvent has good solubility with the grafting monomer, which can promote the penetration and diffusion of vinylamine-based compounds from the channels formed by swelling into the interior of polypropylene, effectively improving the grafting rate. The initiator solution is slowly dropped into the matrix solution at a rate of 1 - 3 wt% / min. This rate improves the synchronization of free radical generation and monomer diffusion, avoiding the homopolymerization side reaction caused by the instantaneous or local excessive concentration of the initiator. After the dropping is completed, the reaction continues for 2 - 4 h to allow the unreacted vinylamine-based compounds to be fully grafted onto the polypropylene chain segments. By controlling the dropping rate and reaction time, the grafting rate is increased, and the amount of homopolymer formed decreases, significantly superior to the traditional melt grafting process.

[0019] Exemplarily, the grafting solution is slowly dropped into the matrix solution at a rate of 2 wt% / min, and the time required for the complete dropping of the grafting solution is 50 min.

[0020] In any of the above technical solutions, the acid scavenger is zinc stearate and / or zinc oxide.

[0021] In any of the above technical solutions, the antioxidant is selected from at least one of amine-based, phenol-based, and phosphite-based antioxidants.

[0022] In any of the above technical solutions, the ultraviolet absorber is selected from at least one of benzotriazole-based, triazine-based, and benzophenone-based ultraviolet absorbers.

[0023] In any of the above technical solutions, the modified filler is prepared by emulsion radical copolymerization of vinylated filler, vinyl nitrogen-containing heterocycle, and α-olefin with a mass ratio of 100:5 - 15:20 - 30.

[0024] In any of the above technical solutions, the vinyl nitrogen-containing heterocycle is selected from one or more of vinyl imidazole, vinyl pyrrolidone, and vinyl pyridine.

[0025] In any of the above technical solutions, the α-olefin is a C6 - C12 α-olefin.

[0026] In any of the above technical solutions, the vinylated filler is prepared by spray treatment of filler and vinyl silane coupling agent with a mass ratio of 100:1 - 5. Specifically, the vinyl silane coupling agent can be dissolved in a solvent such as ethanol, and the solution is sprayed onto the surface of the filler through a spray process and dried to obtain the vinylated filler.

[0027] In any of the above technical solutions, the filler is selected from one or more of calcium carbonate, silica, alumina, zinc oxide, talcum powder, montmorillonite, and mica powder.

[0028] In any of the above technical solutions, the average particle size of the filler is 0.5 - 3 μm.

[0029] In the present application, the filler is surface graft-modified to introduce alkyl chain segments and nitrogen-containing heterocycles. The alkyl chain segments (such as C6 - C12 α-olefins) enhance the interfacial bonding between the filler and the polypropylene matrix through the principle of like dissolves like, reducing the mechanical defects caused by agglomeration; the nitrogen-containing heterocycles form a coordination network with the amino groups in the aminated polypropylene through the bridging action of metal ions (such as Zn 2+ ) and form a hydrogen bond network with the amino groups through the N-H bonds in the heterocycles. This dual action can effectively inhibit the migration and precipitation of weather resistance additives.

[0030] In a second aspect, the present application provides a method for preparing a weather-resistant and anti-aging polypropylene material, which includes: according to the raw material ratio of any of the above polypropylene materials, mixing polypropylene, vinylamine compound-grafted polypropylene, modified filler, ultraviolet absorber, hindered amine light stabilizer, antioxidant, and acid remover evenly, then feeding them into a screw extruder, and continuing to knead at 190 - 220 °C for 5 - 10 minutes, and then extruding and pelletizing to obtain the product.

[0031] In summary, the present application has the following beneficial effects: Through the synergistic cooperation of the aminated polypropylene compatibilizer, modified filler, and weather resistance additives, the present application realizes the simultaneous improvement of the weather resistance and anti-yellowing performance of the polypropylene material. The neutralization effect and coordination effect of the amino groups in the aminated polypropylene effectively inhibit acid degradation and metal ion catalysis. The low-temperature solvent method of the grafting process avoids the breakage of polypropylene chains and reduces the risk of yellowing. The introduction of alkyl chains and nitrogen-containing heterocycles on the surface of the filler further blocks the migration of additives and enhances the interfacial stability through the hydrogen bond-coordination network. The material is not easily yellowed after QUV aging, has a high notched impact strength, and a low migration rate of antioxidant, and is suitable for long-term use in outdoor high-ultraviolet and high-humidity environments. Specific Embodiments Preparation Examples

[0032] In the following preparation examples, the grafting rate of the vinylamine compound-grafted polypropylene was measured by the following method: 1. Remove unreacted vinylamine compound monomers, homopolymers, and residual solvents The grafted polypropylene sample was crushed into powder (particle size ≤ 1 mm), and a Soxhlet extractor was used to extract with acetone as the solvent for 48 hours (flow rate 1 - 2 drops / second). After extraction, the sample was dried to a constant weight at 70 °C under vacuum (mass change < 0.1%).

[0033] 2. Elemental analysis (nitrogen content determination) Instrument: Elemental analyzer (CHNS - O mode, such as Elementar Vario EL I).

[0034] Procedure: Weigh the dried sample (about 5 mg) accurately to 0.001 mg, wrap the sample in a tin foil boat, and send it into the combustion tube to be completely oxidized at a high temperature (≥950 °C). Detect the amount of ammonia released and quantify the ammonia content through a thermal conductivity detector (TCD). Repeat 3 times and take the average value to ensure that the relative standard deviation (RSD) < 2%.

[0035] Grafting rate = measured nitrogen content / theoretical nitrogen content of vinylamine - based compound × 100%; Among them, the theoretical nitrogen content of vinylbenzylamine = 14.01 / 133.19 × 100% = 10.52%; The theoretical nitrogen content of vinylaniline = 14.01 / 119.16 × 100% = 11.76%; The theoretical nitrogen content of the mixed monomer (vinylbenzylamine M1 + vinylaniline M1) = M1 / (M1 + M2) × 10.52% + M2 / (M1 + M2) × 11.76%.

[0036] Preparation Example 1, a vinylamine - based compound grafted polypropylene, was prepared as follows: Add 0.5 kg of polypropylene (grade PPH - T03) and 5 kg of xylene to a closed reaction kettle, stir and heat up to 110 °C for 50 min of swelling; stir and mix 0.06 kg of vinylbenzylamine, 0.02 kg of vinylaniline and 0.05 kg of N,N - dimethylformamide, add them to the matrix solution, and stir for 40 min. Then take 0.015 kg of benzoyl peroxide and mix it with xylene to prepare an initiator solution with a concentration of 10 wt%; add the initiator solution to the matrix solution mixed with graft monomers at a rate of 2 wt% / min. After adding, heat up to 120 °C and react for 3 h. Cool down to 50 °C, pour the reaction solution into acetone for precipitation, soak and wash it with ethanol 3 times, and dry it in vacuum at 70 °C for 24 h to obtain vinylamine - based compound grafted polypropylene with a grafting rate of 3.16%.

[0037] Preparation Example 2, a vinylamine - based compound grafted polypropylene, was prepared as follows: Add 0.5 kg of polypropylene (grade PPH-T03) and 4 kg of decalin into a closed reaction kettle, stir and heat up to 110 °C, and swell for 80 min; stir and mix 0.02 kg of vinylbenzylamine, 0.01 kg of vinylaniline and 0.02 kg of methyl ethyl ketone, add them into the matrix solution, and stir for 30 min. Then take 0.01 kg of diisopropyl peroxide and mix it with decalin to prepare an initiator solution with a concentration of 10 wt%; add the initiator solution into the matrix solution mixed with graft monomers at a rate of 3 wt% / min. After the addition is completed, heat up to 110 °C and react for 4 h. Cool down to 50 °C, pour the reaction solution into acetone for precipitation, soak and wash with ethanol 3 times, and dry in vacuum at 80 °C for 18 h to obtain vinylamine compound-grafted polypropylene with a grafting rate of 2.91%.

[0038] Preparation Example 3, a vinylamine compound-grafted polypropylene, was prepared by the following method: Add 0.5 kg of polypropylene (K1003, Yanshan Petrochemical) and 6 kg of xylene into a closed reaction kettle, stir and heat up to 120 °C, and swell for 30 min; stir and mix 0.05 kg of vinylbenzylamine, 0.025 kg of vinylaniline and 0.06 kg of N,N-dimethylformamide, add them into the matrix solution, and stir for 60 min. Then take 0.025 kg of diisopropyl peroxide and mix it with xylene to prepare an initiator solution with a concentration of 20 wt%; add the initiator solution into the matrix solution mixed with graft monomers at a rate of 1 wt% / min. After the addition is completed, heat up to 130 °C and react for 2 h. Cool down to 50 °C, pour the reaction solution into acetone for precipitation, soak and wash with ethanol 3 times, and dry in vacuum at 80 °C for 24 h to obtain vinylamine compound-grafted polypropylene with a grafting rate of 3.35%.

[0039] Preparation Example 4, a vinylamine compound-grafted polypropylene, is different from Preparation Example 1 in that vinylaniline is replaced with vinylbenzylamine of equal mass to obtain vinylamine compound-grafted polypropylene with a grafting rate of 2.72%.

[0040] Preparation Example 5, a vinylamine compound-grafted polypropylene, is different from Preparation Example 1 in that vinylbenzylamine is replaced with vinylaniline of equal mass to obtain vinylamine compound-grafted polypropylene with a grafting rate of 3.24%.

[0041] Preparation Example 6, a vinylamine compound-grafted polypropylene, is different from Preparation Example 1 in that the initiator solution is added into the matrix solution mixed with graft monomers at a rate of 5 wt% / min to obtain vinylamine compound-grafted polypropylene with a grafting rate of 2.63%.

[0042] Preparation Example 7: A vinylamino compound-grafted polypropylene, which is different from Preparation Example 1 in that the initiator solution is added to the matrix solution mixed with the graft monomer at a rate of 0.5 wt% / min to obtain a vinylamino compound-grafted polypropylene with a grafting rate of 2.70%.

[0043] Preparation Example 8: A vinylamino compound-grafted polypropylene, which is different from Preparation Example 1 in that the co-solvent (N,N-dimethylformamide) is replaced with the same mass of the main solvent (xylene) to obtain a vinylamino compound-grafted polypropylene with a grafting rate of 1.75%.

[0044] Preparation Example 9: A vinylamino compound-grafted polypropylene, which is different from Preparation Example 1 in that vinylphenylamine is used to replace vinylbenzylamine and is prepared by a melt grafting process. The specific steps are as follows: Add 0.5 kg of dried polypropylene resin, 0.02 kg of vinylbenzylamine, 0.01 kg of vinylphenylamine, and 0.01 kg of DCP into a high-speed mixer. Set the mixing temperature at 40 °C, the rotation speed at 500 rpm, and the mixing time at 10 minutes to ensure that the monomers and the initiator are evenly dispersed on the surface of the polypropylene particles. Transfer the premix to an internal mixer (volume 5 L), and introduce ammonia gas to displace the air (flow rate 10 L / min, for 5 minutes). The internal mixing temperature is 175 °C, the rotor speed is 60 rpm, and the internal mixing reaction time is 12 minutes to obtain a vinylamino compound-grafted polypropylene with a grafting rate of 1.42%.

[0045] Preparation Example a: A modified filler is prepared according to the following steps: Preparation of vinylated filler Dissolve 30 g of vinyltrimethoxysilane in 500 mL of ethanol and stir until dissolved. Place 1 kg of calcium carbonate (average particle size 1.5 μm) in a fluidized bed, control the spray pressure at 0.3 MPa, and evenly spray the silane ethanol solution on the surface of the filler. After spraying, dry it with hot air at 80 °C for 2 hours to obtain the vinylated filler.

[0046] Emulsion free radical copolymerization reaction Disperse the above-obtained vinylated filler, 75 g of 1-vinylimidazole, and 187.5 g of 1-octene in 5 L of deionized water, add 10 g of sodium dodecyl sulfate and 20 g of OP-10, and perform high-speed shear emulsification for 30 minutes. Heat up to 75 °C, pass ammonia gas to remove oxygen for 30 minutes, and add 5 g of potassium persulfate (dissolved in 50 mL of water). Keep the reaction temperature at 75 °C, the stirring rate at 300 rpm, and react for 5 hours. After the reaction, cool to room temperature, perform centrifugal separation, wash with water 3 times, and dry in vacuum at 60 °C for 12 hours to obtain the modified filler.

[0047] Preparation Example b: A modified filler is prepared according to the following steps: Preparation of Vinylated Filler Dissolve 10 g of vinyltriethoxysilane in 300 mL of ethanol and stir until dissolved. Place 1 kg of silica (average particle size 0.5 μm) in a fluidized bed, control the spray pressure at 0.2 MPa, and evenly spray the silane ethanol solution on the surface of the filler. After spraying, dry with hot air at 60 °C for 4 hours to obtain the vinylated filler.

[0048] Emulsion Radical Copolymerization Reaction Add the above-obtained vinylated filler, 51.5 g of 1-vinyl-2-pyrrolidone, and 206 g of 1-pentene to 3 L of deionized water, add 25 g of OP-10, and perform high-speed shear emulsification for 30 minutes. Heat up to 70 °C, deoxygenate by passing ammonia for 20 minutes, and add 3 g of ammonium persulfate (dissolved in 30 mL of water). Maintain the reaction temperature at 70 ± 2 °C and the stirring rate at 300 rpm, and react for 4 hours. After the reaction, cool to room temperature, perform centrifugal separation, wash with water 3 times, and dry in vacuum at 50 °C for 8 hours to obtain the modified filler.

[0049] Preparation Example c, a modified filler, is prepared according to the following steps: Preparation of Vinylated Filler Dissolve 50 g of vinyltrimethoxysilane in 800 mL of ethanol and stir until dissolved. Spray 1 kg of calcium carbonate (average particle size 3 μm) into a spray drying tower, with an inlet temperature of 120 °C and a spray pressure of 0.4 MPa, and continuously spray in the silane solution. The outlet temperature is 80 °C, and the vinylated filler is obtained after drying.

[0050] Emulsion Radical Copolymerization Reaction Disperse the above-obtained vinylated filler, 154.5 g of 4-vinylpyridine, and 309 g of 1-dodecene in 8 L of deionized water, add 30 g of Tween-80 and 15 g of sodium dodecylbenzenesulfonate, and perform high-speed shear emulsification for 30 minutes. Heat up to 80 °C, add 8 g of azobisisobutyronitrile (dissolved in 80 mL of ethanol) under nitrogen protection, maintain the reaction temperature at 80 °C and the stirring rate at 300 rpm, and react for 6 hours. After the reaction, filter, wash with methanol 3 times, and dry in vacuum at 70 °C for 24 hours to obtain the modified filler.

[0051] Preparation Example d, a modified filler, is different from Preparation Example a in that 1-octene is replaced with an equal mass of vinylimidazole.

[0052] Preparation Example e, a modified filler, is different from Preparation Example a in that 1-octene is replaced with an equal mass of 1-vinylimidazole. Examples

[0053] Example 1, a weather-resistant and anti-aging polypropylene material, is prepared according to the following method: Add 1 kg of polypropylene resin (grade PPH-T03), 35 g of vinylamine compound grafted polypropylene (Preparation Example 1), 100 g of modified filler (Preparation Example a), 5.5 g of ultraviolet absorber (UV326), 6 g of hindered amine light stabilizer (HALS-770), 8.5 g of antioxidant 168, and 3 g of zinc stearate into a high-speed mixer. Set the mixing temperature at 40 °C, the rotation speed at 800 rpm, and the mixing time at 15 minutes to uniformly disperse the materials and obtain a premix.

[0054] Feed the premix into a twin-screw extruder (screw diameter 50 mm, length-diameter ratio 40:1). Set the extrusion temperature zones as follows: zone 1 at 190 °C, zone 2 at 200 °C, zone 3 at 205 °C, zone 4 at 210 °C, and the die head at 205 °C. The screw rotation speed is 200 rpm, the vacuum degassing pressure is -0.08 MPa, and the melt pressure is 12 MPa. After the materials are melt-kneaded for 6 minutes, they are pelletized by an underwater pelletizer (pelletizing water temperature 25 °C), and the pellets are dried by hot air at 60 °C for 2 hours to obtain the product.

[0055] Example 2. A weather-resistant and anti-aging polypropylene material is prepared as follows: Add 1 kg of polypropylene resin (grade PPH-Y24), 20 g of vinylamine compound grafted polypropylene (Preparation Example 2), 50 g of modified filler (Preparation Example b), 3.0 g of ultraviolet absorber (UV-531), 2 g of hindered amine light stabilizer (HALS-622), 12 g of antioxidant 1010, and 3 g of zinc stearate into a high-speed mixer. Set the mixing temperature at 40 °C, the rotation speed at 500 rpm, and the mixing time at 20 minutes to uniformly disperse the materials and obtain a premix.

[0056] Feed the premix into a twin-screw extruder (screw diameter 50 mm, length-diameter ratio 40:1). Set the extrusion temperature zones as follows: zone 1 at 185 °C, zone 2 at 190 °C, zone 3 at 195 °C, zone 4 at 200 °C, and the die head at 195 °C. The screw rotation speed is 200 rpm, the vacuum degassing pressure is -0.05 MPa, and the melt pressure is 8 MPa. After the materials are melt-kneaded for 5 minutes, they are pelletized by an underwater pelletizer (pelletizing water temperature 25 °C), and the pellets are dried by hot air at 60 °C for 2 hours to obtain the product.

[0057] Example 3. A weather-resistant and anti-aging polypropylene material is prepared as follows: Add 1 kg of polypropylene resin (grade PPH-T03), 50 g of vinylamino compound grafted polypropylene (Preparation Example 3), 150 g of modified filler (Preparation Example c), 8 g of ultraviolet absorber (UV-1577), 10 g of hindered amine light stabilizer (HALS-994), 5 g of antioxidant 1076, 2 g of zinc stearate, and 3 g of zinc oxide (average particle size 50 nm) into a high-speed mixer. Set the mixing temperature at 40 °C, the rotation speed at 800 rpm, and the mixing time at 15 minutes to uniformly disperse the materials and obtain a premix.

[0058] Put the premix into a twin-screw extruder (screw diameter 50 mm, length-diameter ratio 40:1). Set the extrusion temperature zones as follows: zone 1 at 200 °C, zone 2 at 210 °C, zone 3 at 215 °C, zone 4 at 220 °C, and the die head at 215 °C. The screw rotation speed is 200 rpm, the vacuum degassing pressure is -0.1 MPa, and the melt pressure is 12 MPa. After the materials are melt-mixed for 10 minutes, they are pelletized by an underwater pelletizer (pelletizing water temperature 25 °C), and the pellets are dried in hot air at 60 °C for 2 hours to obtain the product.

[0059] Example 4, a weather-resistant and anti-aging polypropylene material, which is different from Example 1 in that the vinylamino compound grafted polypropylene of Preparation Example 4 with the same mass is used to replace the vinylamino compound grafted polypropylene of Preparation Example 1.

[0060] Example 5, a weather-resistant and anti-aging polypropylene material, which is different from Example 1 in that the vinylamino compound grafted polypropylene of Preparation Example 5 with the same mass is used to replace the vinylamino compound grafted polypropylene of Preparation Example 1.

[0061] Example 6, a weather-resistant and anti-aging polypropylene material, which is different from Example 1 in that the vinylamino compound grafted polypropylene of Preparation Example 6 with the same mass is used to replace the vinylamino compound grafted polypropylene of Preparation Example 1.

[0062] Example 7, a weather-resistant and anti-aging polypropylene material, which is different from Example 1 in that the vinylamino compound grafted polypropylene of Preparation Example 7 with the same mass is used to replace the vinylamino compound grafted polypropylene of Preparation Example 1.

[0063] Example 8, a weather-resistant and anti-aging polypropylene material, which is different from Example 1 in that the modified filler of Preparation Example d with the same mass is used to replace the modified filler of Preparation Example a.

[0064] Example 9, a weather-resistant and anti-aging polypropylene material, which is different from Example 1 in that the modified filler of Preparation Example e with the same mass is used to replace the modified filler of Preparation Example a.

[0065] Example 10, a weather-resistant and anti-aging polypropylene material, which is different from Example 1 in that the acid scavenger is calcium stearate. Comparative Example

[0066] Comparative Example 1, a weather-resistant and anti-aging polypropylene material, which is different from Example 1 in that the polypropylene grafted with vinylamine compound of Preparation Example 8 is used to replace the polypropylene grafted with vinylamine compound of Preparation Example 1 in equal mass.

[0067] Comparative Example 2, a weather-resistant and anti-aging polypropylene material, which is different from Example 1 in that the commercially available maleic anhydride grafted polypropylene (grade PO-1015) is used to replace the polypropylene grafted with vinylamine compound of Preparation Example 1 in equal mass.

[0068] Comparative Example 3, a weather-resistant and anti-aging polypropylene material, which is different from Example 1 in that the polypropylene grafted with vinylamine compound of Preparation Example 9 is used to replace the polypropylene grafted with vinylamine compound of Preparation Example 1 in equal mass. Performance detection test

[0069] Test 1: Notched impact strength test Specimen preparation: The granules obtained from each example and comparative example were injection molded into standard notched impact test specimens (size 80×10×4 mm, notch depth 2 mm, angle 45°).

[0070] Test method: Refer to ISO 179-1:2010 "Plastics - Determination of Charpy impact properties" for testing. The test parameters were set as follows: impact speed 3.8 m / s; test temperature 23±2°C; 10 specimens were tested in each group, and the average value was taken.

[0071] Test 2: Weather resistance test Specimen preparation: The granules obtained from each example and comparative example were injection molded into standard test specimens (size 150×80×2 mm) without defects such as scratches and bubbles on the surface. The specimens were conditioned in an environment of 23°C and 50% RH for 48 hours.

[0072] Test method: Refer to ASTM G154-16 "Standard Practice for Operating Fluorescent UV Lamps for Exposure of Nonmetallic Materials", and a UV weather resistance test chamber (UVA-340 lamp tube, wavelength peak 340 nm) was used for cyclic testing. Cyclic conditions: black standard temperature 63°C, irradiation intensity 0.60 W / m 2 , lasting for 4 hours; condensation stage black standard temperature 51°C, humidity 100%, lasting for 2 hours; total cyclic duration 1000 hours. After the cycle was completed, a color difference meter (D65 light source, 10° viewing angle) was used to measure the color difference before and after aging, recorded as the yellowing index (ΔE); 10 specimens were measured in each group, and the average value was taken. And the notched impact strength was measured again according to the method in Test 1.

[0073] Test 3: Anti-precipitation performance test Specimen preparation: The particles obtained in each example and comparative example were pressed into a film with a thickness of 0.5 mm by a flat vulcanizing machine (180 °C, 10 MPa pressure). The specimens were cut into a size of 100×100 mm, and after cutting, the specimens were conditioned at 23 °C and 50% RH for 24 hours, and the initial mass (M0) was accurately weighed.

[0074] Test method: The film was placed in an oven at 70 °C for 240 hours (simulating long-term use); the specimen was taken out, and the surface precipitate was wiped with absolute ethanol (ensuring that the matrix was not damaged), and the mass after aging (M1) was weighed after drying. Calculate the precipitation amount ΔM = M0 - M1; 10 specimens were measured in each group, and the average value was taken.

[0075] Table 1. Test results of performance tests

[0076] This specific embodiment is only an interpretation of the present application, and it does not limit the present application. After reading this specification, those skilled in the art can make modifications without creative contributions to this embodiment as needed, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A weather-resistant and anti-aging polypropylene material, characterized in that, It comprises raw materials in the following parts by mass: 100 parts of polypropylene resin, 2 - 5 parts of vinylamino compound-grafted polypropylene, 5 - 15 parts of modified filler, 0.3 - 0.8 part of ultraviolet absorber, 0.2 - 1.0 part of hindered amine light stabilizer, 0.5 - 1.2 parts of antioxidant, 0.1 - 0.5 part of acid remover; The vinylamino compound-grafted polypropylene is prepared by free radical copolymerization of polypropylene and vinylamino compound with a mass ratio of 100:5 - 15 in a reaction solvent, and the reaction temperature is 110 - 130°C; the reaction solvent comprises a main solvent and a co-solvent with a mass ratio of 100:0.5 - 1.2; the main solvent is selected from xylene or decalin, and the co-solvent is selected from N,N-dimethylformamide or methyl ethyl ketone.

2. The polypropylene material according to claim 1, wherein The preparation method of the vinylamino compound-grafted polypropylene comprises: Adding polypropylene into the main solvent, stirring evenly, heating to 110 - 130°C, and stirring to swell the polypropylene to obtain a matrix solution; mixing the vinylamino compound with the co-solvent, adding it to the matrix solution, and stirring for 30 - 60 min; Mixing the initiator with the solvent, stirring to prepare an initiator solution, dropping the initiator solution into the matrix solution, and after the dropping is completed, reacting for 2 - 4 h to obtain a reaction solution; cooling to below 60°C, pouring the reaction solution into acetone to precipitate, soaking and washing the precipitate with absolute ethanol, and drying in vacuum to obtain the product.

3. The polypropylene material according to claim 1, wherein The vinylamino compound is vinylbenzylamine and / or vinylaniline.

4. The polypropylene material according to claim 3, characterized in that, The vinylamino compound is vinylbenzylamine and / or vinylaniline with a mass ratio of 2 - 3:

1.

5. The polypropylene material according to claim 2, wherein The swelling time is 30 - 80 min.

6. The polypropylene material according to claim 2, characterized in that, The dropping rate of the initiator solution is 1 - 3 wt% / min.

7. The polypropylene material according to claim 2, wherein The initiator is diisopropylbenzene peroxide, di-tert-butyl peroxide or benzoyl peroxide.

8. The polypropylene material according to claim 1, characterized in that, The acid remover is zinc stearate and / or zinc oxide.

9. The polypropylene material according to claim 1, characterized in that, The modified filler is prepared by free radical copolymerization of vinylated filler, vinyl nitrogen-containing heterocycle and α-olefin with a mass ratio of 100:5 - 15:20 - 30.

10. A preparation method of a weather-resistant and anti-aging polypropylene material, characterized in that, It comprises: According to the raw material ratio of the polypropylene material described in any one of claims 1 - 9, mixing polypropylene, vinylamino compound-grafted polypropylene, modified filler, ultraviolet absorber, hindered amine light stabilizer, antioxidant, and acid remover evenly, then feeding them into a screw extruder, and continuing to knead at 190 - 220°C for 5 - 10 minutes, and then extruding and pelletizing to obtain the product.

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