Polypropylene composition as well as preparation method and application thereof

Abstract

The invention discloses a polypropylene composition as well as a preparation method and application thereof, and belongs to the technical field of high polymer materials. The polypropylene composition provided by the invention is prepared from the following components in parts by mass: 68 to 92 parts of polypropylene resin, 8 to 32 parts of inorganic filler, 0.05 to 0.6 part of antioxidant, 0.1 to 1 part of ultraviolet absorbent, 0.05 to 0.6 part of light stabilizer and 0.1 to 0.6 part of modified nano titanium dioxide. The polypropylene composition provided by the invention can have good ultraviolet resistance, especially UV-C resistance, by selecting the components in proper parts by mass and matching the components with one another, and the change of mechanical properties and chromatic aberration is small before and after the polypropylene composition is irradiated by ultraviolet rays or UV-C; and the prepared polypropylene composition has good mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and particularly relates to a polypropylene composition, its preparation method and application. Background Technology

[0002] Polypropylene has a large number of tertiary carbon atoms (carbon atoms connecting three carbon atoms) in its molecular backbone. The CH bonds on these tertiary carbon atoms have relatively low bond energies and are very unstable. Ultraviolet radiation is classified into UV-A, UV-B, and UV-C based on wavelength. UV-C has the shortest wavelength (100-280 nm) and the highest energy, making it the most destructive to polymers. When high-energy UV-C photons (wavelength 100-280 nm) strike the polymer, they easily cause homolytic cleavage, forming free radicals and triggering a series of photo-oxidative degradation reactions. While most UV-C in nature is absorbed by the ozone layer, artificial UV-C light sources (such as germicidal lamps) are highly destructive. This energy exceeds the bond energies of many chemical bonds in the polypropylene molecule, enough to directly break these bonds, leading to molecular chain breakage (degradation) or cross-linking. These inherent factors cause polypropylene to easily break molecular chains under UV-C irradiation, leading to brittleness, a significant decrease in mechanical strength (such as tensile strength and impact strength), surface powdering, cracking, roughening of the material surface, microcracks, or even powdering and peeling off, and color changes such as yellowing or fading.

[0003] Conventional UV stabilizers (benzotriazoles, benzophenones, HALS) primarily work by absorbing energy from UV-A (315-400 nm) and UV-B (280-315 nm) rays and dissipating it as harmless heat, or by scavenging free radicals to interrupt degradation reactions. The energy level structures of these organic stabilizer molecules are designed for UV-A / B; when faced with the much higher energy of UV-C, they themselves are rapidly destroyed and degraded, failing to provide lasting protection and potentially even accelerating material aging.

[0004] Chinese patent CN 114773743A discloses a UV-C resistant HIPS resin composition and its preparation method. The material is composed of GPPS, SEBS, tert-octyl salicylic acid ester, 2-cyano-phenylethyl salicylic acid ester, benzotriazole, and titanium dioxide. The material can withstand continuous UV-C irradiation (250nm, 20W for one year) with a color difference of <5 and an impact retention rate of over 70%. However, the added benzotriazole UV absorber is mainly designed to resist UV-B and UV-A and is a broad-spectrum UV absorber that can effectively absorb ultraviolet rays of 280-380 nm. Although tert-octyl salicylic acid ester and 2-cyano-phenylethyl salicylic acid ester have effective absorption bands in the UV-B region of 280-315nm, their absorption in the UC-C band (200-280nm) is limited. It is necessary to add at least 10% or more of anatase titanium dioxide to improve the material's UV-C shielding effect, which will damage the initial mechanical properties of the material. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a polypropylene composite material with good UV resistance, especially good UV-C resistance, and excellent mechanical properties, as well as its preparation method and application.

[0006] To achieve the above objectives, in a first aspect, the present invention provides a polypropylene composition comprising the following components in parts by weight: 68-92 parts polypropylene resin, 8-32 parts inorganic filler, 0.05-0.6 parts antioxidant, 0.1-1 part UV absorber, 0.05-0.6 parts light stabilizer, 0.1-0.6 parts modified nano titanium dioxide; The ultraviolet absorber includes triazine ultraviolet absorbers; The modified nano-titanium dioxide includes at least two of the following: first modified nano-titanium dioxide, second modified nano-titanium dioxide, third modified nano-titanium dioxide, and fourth modified nano-titanium dioxide. The first modified nano-titanium dioxide includes nano-titanium dioxide and a coating layer disposed on at least a portion of the surface of the nano-titanium dioxide, the coating layer including cerium dioxide; The second modified nano-titanium dioxide includes nano-titanium dioxide and a coating layer disposed on at least a portion of the surface of the nano-titanium dioxide, the coating layer including silicon dioxide; The third modified nano-titanium dioxide includes nano-titanium dioxide and a coating layer disposed on at least a portion of the surface of the nano-titanium dioxide, the coating layer including zirconium dioxide; The fourth modified nano-titanium dioxide is nano-titanium dioxide that has been surface-treated with diisocyanate compounds.

[0007] The polypropylene composition provided by this invention, by selecting appropriate mass parts of the components and coordinating the components with each other, can have good resistance to ultraviolet light, especially UV-C resistance. The mechanical properties and color difference changes little before and after ultraviolet or UV-C irradiation; and the prepared polypropylene composition has good mechanical properties.

[0008] Specifically, TiO2 is a wide-bandgap semiconductor (anatase approximately 3.2 eV, rutile approximately 3.0 eV) with extremely strong absorption and reflection capabilities for ultraviolet light (wavelength <388 nm). Adding it to polymers is like putting a "metallic armor" on the polymer, blocking most harmful UV radiation and protecting the polymer molecular chains from direct damage by the energy of ultraviolet light. However, when TiO2 absorbs ultraviolet light with energy higher than its bandgap, it excites the generation of high-energy photogenerated electrons (electrons). - ) and holes (h + These electrons and holes migrate to the surface of TiO2 particles and react with water (H2O) and oxygen (O2) adsorbed on the surface to generate hydroxyl radicals (·OH) and superoxide radicals (·O2). - Reactive oxygen species (ROS) such as α, β, and γ are present. These free radicals have extremely strong oxidizing power and can indiscriminately attack and break the molecular chains of polymers (oxidative degradation), leading to yellowing, brittleness, pulverization, and a sharp decline in mechanical properties. This invention, by selecting specific types of modified nano-titanium dioxide compounded together, can effectively improve the stability of TiO2 in UV, especially UV-C, environments, providing stable physical shielding. Combined with triazine UV absorbers to consume the small amount of residual UV-C penetrating the titanium dioxide shielding layer, and assisted by light stabilizers and specific types of antioxidants, it effectively quenches free radicals generated on the titanium dioxide surface due to photocatalysis, preventing free radicals from attacking polymer chains, thus constructing a physical-chemical synergistic protection network. This achieves excellent UV resistance in the product while maintaining good mechanical properties with relatively low additive amounts.

[0009] More specifically, cerium oxide (CeO2) is a rare-earth ultraviolet absorber. CeO2 has a very strong and broad absorption band in the UV-C and UV-B regions. After absorbing ultraviolet light, electrons in CeO2 jump from the 2p orbital of oxygen to the 4f orbital of cerium, resulting in CeO2... 4+ Reduced to Ce 3+ Simultaneously, an oxygen vacancy is created; light energy is consumed in this process; more importantly, Ce... 3+ The site can catalyze the decomposition of peroxides (such as ·OOH generated by TiO2 photocatalysis) and quench free radicals (such as ·OH); Ce 3+ It is oxidized back to Ce in this process. 4+This completes a catalytic cycle. Zirconia (ZrO2) has a high refractive index (~2.1-2.2), which can more effectively reflect and scatter ultraviolet light, including UV-C, reducing light intrusion from the very first step. ZrO2 itself is also a semiconductor; when it absorbs UV-C photons, it also generates electron-hole pairs. ZrO2 holes have extremely strong oxidizing properties and will preferentially oxidize the Zr on its surface. 4+ The light energy is dissipated rapidly as harmless thermal energy by ionizing or adsorbing hydroxyl groups, rather than oxidizing the external organic matrix. Simultaneously, the recombination rate of its electron-hole pairs is extremely fast, quickly dissipating the light energy as harmless thermal energy. This process is equivalent to "actively intercepting" high-energy photons and "detoxifying" them, protecting the internal TiO2. SiO2 is a wide-bandgap semiconductor that can form an inert physical barrier on the surface of TiO2 particles. This barrier prevents TiO2 from directly contacting the surrounding environment (such as oxygen, water, and the polymer matrix), thereby suppressing, to some extent, the photogenerated holes (h holes) generated by TiO2 under ultraviolet light. + ) and electrons (e - The presence of SiO2 in redox reactions reduces the harmful effects of photocatalytic activity. SiO2 can also reduce the number of photons reaching the TiO2 core by reflecting and scattering some ultraviolet light. One end of the diisocyanate molecule (OCN-R-NCO) reacts with the hydroxyl groups on the TiO2 surface, while the other end retains the -NCO active group exposed, thus achieving "coating" and "functionalization" of TiO2. This effectively avoids photocatalytic damage and improves the compatibility of titanium dioxide with organic substrates, enhancing its performance in composite materials.

[0010] Furthermore, the present invention selects at least two of the following modified nano-titanium dioxide: first modified nano-titanium dioxide, second modified nano-titanium dioxide, third modified nano-titanium dioxide, and fourth modified nano-titanium dioxide. The different coating materials or surface modification materials can synergistically improve the stability of titanium dioxide in the UV-C environment from different perspectives, thereby improving the overall performance of the composite material.

[0011] For example, the polypropylene resin can be any point value or any two-point range between 68 and 92 parts, such as 70-90 parts, or 68, 60, 62, 65, 68, 70, 72, 75, 78, 80, 82, 85, 88, 90, 92, etc.; the inorganic filler can be any point value or any two-point range between 8 and 32 parts, such as 10-30 parts. Alternatively, it can be 8 parts, 10 parts, 12 parts, 15 parts, 18 parts, 20 parts, 22 parts, 25 parts, 28 parts, 30 parts, 32 parts, etc.; the antioxidant can be any point value or any two-point range value between 0.05-0.6 parts, for example, it can be 0.1-0.5 parts, or 0.05 parts, 0.1 parts, 0.15 parts, 0.2 parts, 0.25 parts, 0.3 parts, 0.35 parts, 0.4 parts, 0.45 parts, 0.5 parts, 0 The UV absorber can be any point value or any two-point range value between 0.1 and 1 part, such as 0.2-0.8 parts, or 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1 part, etc.; the light stabilizer can be any point value or any two-point range value between 0.05 and 0.6 parts, such as 0.1-0.6 parts. 5 parts, or 0.05 parts, 0.1 parts, 0.15 parts, 0.2 parts, 0.25 parts, 0.3 parts, 0.35 parts, 0.4 parts, 0.45 parts, 0.5 parts, 0.55 parts, 0.6 parts, etc.; the modified nano titanium dioxide can be any point value or any two-point range value between 0.1 and 0.6 parts, for example, it can be 0.2-0.5 parts, or 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, etc.

[0012] Preferably, in the polypropylene composition, the mass percentage of polypropylene resin is ≥60%.

[0013] More preferably, the polypropylene composition contains 70-88% polypropylene resin by mass.

[0014] As a preferred embodiment of the polypropylene composition of the present invention, the polypropylene composition comprises the following components in parts by weight: 75-85 parts polypropylene resin, 20-25 parts inorganic filler, 0.2-0.4 parts antioxidant, 0.4-0.6 parts ultraviolet absorber, 0.2-0.4 parts light stabilizer, and 0.3-0.4 parts modified nano titanium dioxide.

[0015] The present invention has found that the mass fraction of a component in a polypropylene composition affects the overall performance of the component. When the mass fraction of the component is further selected within the above-mentioned range, the overall performance of the resulting polypropylene composition is better.

[0016] As a preferred embodiment of the polypropylene composition of the present invention, the polypropylene resin has a melt index of 8-32 g / 10 min at 230°C / 2.16 kg.

[0017] It should be noted that the melt index of the polypropylene resin at 230℃ / 2.16kg was obtained with reference to ISO 1133-12022.

[0018] For example, the melt flow index of the polypropylene resin at 230℃ / 2.16kg can be any point value or any two-point range between 8 and 32 g / 10min, such as 10-30 g / 10min, or 8 g / 10min, 10 g / 10min, 12 g / 10min, 15 g / 10min, 18 g / 10min, 20 g / 10min, 22 g / 10min, 25 g / 10min, 28 g / 10min, 30 g / 10min, 32 g / 10min, etc.

[0019] It should be noted that the present invention does not have any particular limitation on the type of polypropylene, and at least one of homopolymer polypropylene and copolymer polypropylene can be selected.

[0020] In a preferred embodiment of the polypropylene composition of the present invention, the modified nano-titanium dioxide has a mass percentage of 88-97%.

[0021] It should be noted that the mass percentage of nano-titanium dioxide in the modified nano-titanium dioxide is determined by inductively coupled plasma optical emission spectrometry (ICP-OES / MS).

[0022] For example, in the modified nano titanium dioxide, the mass percentage of nano titanium dioxide can be any point value or any two points between 88-97%, such as 90-95%, or 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, etc.

[0023] This invention has found that the mass percentage of nano-titanium dioxide in modified nano-titanium dioxide affects the performance of the nano-titanium dioxide itself, as well as the function of the coating layer or the modification layer. When the mass percentage of nano-titanium dioxide in the modified nano-titanium dioxide is further selected to be 88-97%, the polypropylene composition prepared subsequently has better UV resistance and excellent mechanical properties.

[0024] Preferably, the modified nano-titanium dioxide is rutile titanium dioxide.

[0025] It should be noted that the present invention does not impose any particular limitation on the average particle size of the nano-titanium dioxide in the modified nano-titanium dioxide; the purpose of the present invention can be achieved within the range of 10-50 nm.

[0026] Preferably, in the fourth modified nano-titanium dioxide, the diisocyanate compound includes at least one of toluene-2,4-diisocyanate, diphenylmethane diisocyanate, and isoflurone diisocyanate.

[0027] In a preferred embodiment of the polypropylene composition of the present invention, the ultraviolet absorber further includes a benzotriazole ultraviolet absorber.

[0028] Preferably, the mass ratio of the triazine UV absorber to the benzotriazole UV absorber is (1-4):1.

[0029] For example, the mass ratio of the triazine UV absorber to the benzotriazole UV absorber can be any point value or any two points between (1-4):1, such as 1:1, 2:1, 3:1, 4:1, etc.

[0030] This invention has found that the type of UV absorber affects its absorption capacity for different ultraviolet rays, as well as its compatibility and interaction with other components. When the UV absorber is further selected to include benzotriazole UV absorbers and the mass ratio of the two is within the above range, the overall performance of the obtained product is better.

[0031] As a preferred embodiment of the polypropylene composition of the present invention, the modified nano-titanium dioxide includes a first modified nano-titanium dioxide, wherein the mass percentage of the first modified nano-titanium dioxide is 30-60% based on the mass of the modified nano-titanium dioxide.

[0032] For example, based on the mass of the modified nano-titanium dioxide, the mass percentage of the first modified nano-titanium dioxide can be any point value or any two points between 30% and 60%, such as 33%-50%, or 30%, 32%, 35%, 38%, 40%, 42%, 45%, 48%, 50%, 52%, 55%, 58%, 60%, etc.

[0033] In a preferred embodiment of the polypropylene composition of the present invention, the inorganic filler includes at least one of talc, mica, and barium sulfate.

[0034] This application does not have any special requirements for the size of the inorganic filler, such as 325 mesh to 5000 mesh.

[0035] In a preferred embodiment of the polypropylene composition of the present invention, the antioxidant includes a hindered phenolic antioxidant.

[0036] Preferably, the hindered phenolic antioxidant includes at least one of a single hindered phenolic antioxidant and a double hindered phenolic antioxidant containing a triazine structure.

[0037] For example, the single hindered phenolic antioxidant includes at least one of 3,9-bis[1,1-dimethyl-2-[(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane, di[3-(1,1-dimethylethyl)-4-hydroxy-5-methylphenylpropionic acid]polyethylene glycol, and triethylene glycol ether-di(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate.

[0038] For example, the triazine-containing hindered phenolic antioxidant includes at least one of 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanuric acid and 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione.

[0039] As a preferred embodiment of the polypropylene composition of the present invention, the triazine ultraviolet absorber includes at least one of 2,4,6-tris(2′-hydroxy4′-n-butoxyphenyl)-1,3,5-triazine and 2,4-di(4-biphenyl)-6-(2,4-dihydroxy)phenyl-1,3,5-triazine.

[0040] As a preferred embodiment of the polypropylene composition of the present invention, the benzotriazole ultraviolet absorber includes at least one of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, and 2-(2'-hydroxy-3',5'-di-tert-pentylphenyl)benzotriazole.

[0041] In a preferred embodiment of the polypropylene composition of the present invention, the light stabilizer includes a hindered amine light stabilizer.

[0042] This invention does not have any special requirements regarding the type of light stabilizer.

[0043] For example, the hindered amine light stabilizer includes at least one of the following: a polymer of the reaction product of N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,6-hexanediamine with 2,4,6-trichloro-1,3,5-triazine and N-butyl-1-butylamine and N-butyl-2,2,6,6-tetramethyl-4-piperidinylamine (light stabilizer 2020); poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidinyl)imino}hexamethylene{(2,2,6,6-tetramethyl-4-piperidinyl)imino}] (light stabilizer 944); and bis(2,2,6,6-tetramethyl-4-piperidinyl)succinate (light stabilizer 770).

[0044] As a preferred embodiment of the polypropylene composition of the present invention, the polypropylene composition further includes 0.2-0.5 parts of processing aids.

[0045] For example, the processing aid includes a lubricant. The lubricant includes at least one of polyethylene wax, calcium stearate, and amide lubricants.

[0046] It should be noted that the first modified nano-titanium dioxide, the second modified nano-titanium dioxide, and the third modified nano-titanium dioxide provided by the present invention can be purchased commercially or made in-house. If made in-house, the first modified nano-titanium dioxide and the third modified nano-titanium dioxide can be coated using conventional solid-phase precipitation coating methods in the art, and the second modified nano-titanium dioxide can be coated using conventional sodium silicate acidification coating methods.

[0047] Exemplarily, the preparation methods of the first modified nano-titanium dioxide and the third modified nano-titanium dioxide include the following steps: S1. Disperse nano-TiO2 in deionized water and sonicate to obtain a suspension; S2. Pour the measured coating material and urea into the TiO2 suspension and continue stirring until they are completely dissolved. S3. Heat the reaction system to near the reflux temperature and stir the reaction vigorously at this temperature. S4. After the reaction is complete, stop heating and allow the system to cool naturally while continuing to stir and mature. Then, perform solid-liquid separation. Dry the resulting solid product in a vacuum drying oven. S5. The dried powder is calcined in a muffle furnace to transform the amorphous precursor into a crystalline coating layer.

[0048] It should be noted that the coating material is a soluble metal salt corresponding to a metal oxide; for example, when preparing the first modified nano titanium dioxide, the coating material includes at least one of cerium nitrate and cerium nitrate hexahydrate; when preparing the third modified nano titanium dioxide, the coating material includes at least one of zirconium oxychloride and zirconium oxynitrate.

[0049] In one embodiment, the solid content of the titanium dioxide deionized aqueous solution in S1 is 5%-15%.

[0050] In one embodiment, in S2, the number of moles of urea is 8-12 times the molar amount of the coating material.

[0051] In one embodiment, in step S3, the reaction temperature is 90-95°C, the reaction time is 4-6 hours, and the stirring speed is 300-600 rpm.

[0052] In one embodiment, in step S4, the ripening reaction time is 1-2 hours, the vacuum oven temperature is 90±5℃, and the drying time is 1-2 hours. In one embodiment, in step S5, the calcination temperature is 450-600℃ and the calcination time is 2-4h.

[0053] For example, the preparation method of the second modified nano-titanium dioxide includes the following steps: TiO2 suspension was prepared by ultrasonic dispersion, and a measured amount of sodium silicate was added to adjust the initial pH to 9-10. Sodium silicate was hydrolyzed under acidic conditions to generate silicic acid. Silicic acid is unstable and rapidly condenses into silica sol and deposits on the surface of TiO2 particles. After aging, cooling, washing, filtration and calcination, silica-coated titanium dioxide was produced.

[0054] In one embodiment, the solid content of the titanium dioxide deionized water suspension is controlled at 5%-15%.

[0055] In one embodiment, the maturation is performed by stirring at 60-80°C for 1-2 hours.

[0056] In one embodiment, the calcination temperature is 450-600°C and the calcination time is 2-4 hours.

[0057] For example, the preparation method of the fourth modified nano-titanium dioxide includes the following steps: After drying, nano-titanium dioxide was placed in a flask, followed by the addition of solvent. The mixture was then sonicated to form a uniform and stable suspension. Diisocyanate compounds were then added to the stirred TiO2 suspension, and the mixture was refluxed. Solid-liquid separation was then performed, and the solid was collected, washed, and dried to obtain the fourth modified nano-titanium dioxide.

[0058] In one embodiment, the reflux reaction time is 5-7 hours.

[0059] In one embodiment, the solvent includes at least one of dichloromethane and ethanol.

[0060] In one embodiment, the solid content in the suspension is 2-10%.

[0061] In a second aspect of the invention, the invention provides a method for preparing the polypropylene composition, the method comprising the following steps: mixing the components uniformly and then performing melt mixing, followed by extrusion granulation to obtain the polypropylene composition.

[0062] In a preferred embodiment of the preparation method of the present invention, the temperature of the melt mixing is 170-220℃, and the screw speed during the melt mixing is 350-450 r / min.

[0063] In a third aspect, the present invention provides a component prepared using the polypropylene composition described herein.

[0064] For example, the components include the housing of a medical UV-C disinfection lamp, the housing components of a water treatment disinfection device, etc.

[0065] Compared with the prior art, the beneficial effects of the present invention are as follows: The polypropylene composition provided by this invention, by selecting appropriate mass parts of the components and coordinating the components with each other, can have good resistance to ultraviolet light, especially resistance to UV-C. The mechanical properties and color difference changes little before and after ultraviolet or UV-C irradiation; and the prepared polypropylene composition has good mechanical properties. Detailed Implementation

[0066] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0067] Unless otherwise specified, the reagents, methods and equipment used in this invention are all conventional reagents, methods and equipment in the field; and unless otherwise specified, the raw materials used in parallel experiments are from the same batch.

[0068] Polypropylene resin 1 (PP-1): Homopolymer polypropylene, melt index of 10 g / 10 min at 230℃ / 2.16 kg, PP-HP500N, CNOOC Shell; Polypropylene resin 2 (PP-2): Homopolymer polypropylene, melt index of 30g / 10min at 230℃ / 2.16kg, PPH-Y26 (ZHONGKE), Sinopec Refining & Chemical Co., Ltd. Polypropylene resin 3 (PP-3): Copolymer polypropylene, melt index of 10 g / 10 min at 230℃ / 2.16 kg, PPEP300M, CNOOC Shell; Inorganic filler: talc powder, commercially available; Antioxidant 1: Single hindered phenolic antioxidant, 3,9-bis[1,1-dimethyl-2-[(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane, antioxidant GA80, commercially available; Antioxidant 2: A bihedral phenolic antioxidant containing a triazine structure, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanuric acid, antioxidant 3114, commercially available; Ultraviolet absorber 1 (UV-1): a mixture of 2,4,6-tris(2′-hydroxy-4′-n-butoxyphenyl)-1,3,5-triazine, 2,4-di(4-biphenyl)-6-(2,4-dihydroxy)phenyl-1,3,5-triazine and 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole in a mass ratio of 1:1:1; UV absorber 2 (UV-2): a mixture of 2,4,6-tris(2′-hydroxy-4′-n-butoxyphenyl)-1,3,5-triazine and 2-(2′-hydroxy-3′-tert-butyl-5′-methylphenyl)-5-chlorobenzotriazole in a mass ratio of 4:1; UV absorber 3 (UV-3): a mixture of 2,4,6-tris(2′-hydroxy-4′-n-butoxyphenyl)-1,3,5-triazine, 2,4-di(4-biphenyl)-6-(2,4-dihydroxy)phenyl-1,3,5-triazine and 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole in a mass ratio of 0.5:0.5:1; UV absorber 4 (UV-4): a mixture of 2,4,6-tris(2′-hydroxy4′-n-butoxyphenyl)-1,3,5-triazine and 2,4-di(4-biphenyl)-6-(2,4-dihydroxy)phenyl-1,3,5-triazine in a 1:1 mass ratio; UV absorber 5 (UV-5): 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole; Light stabilizer 1: Hindered amine light stabilizer, a polymer of the reaction products of N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,6-hexanediamine with 2,4,6-trichloro-1,3,5-triazine and N-butyl-1-butylamine and N-butyl-2,2,6,6-tetramethyl-4-piperidinamine, Light stabilizer 2020, BASF; Light stabilizer 2: Hindered amine light stabilizer, bis(2,2,6,6-tetramethyl-4-piperidinyl)succinate, light stabilizer 770, XinXu Chemical; Modified nano-titanium dioxide 1 (TiO2-M1): A mixture formed by first modified nano-titanium dioxide 1 and second modified nano-titanium dioxide in a mass ratio of 1:2; Modified nano-titanium dioxide 2 (TiO2-M2): A mixture formed by first modified nano-titanium dioxide 1 and second modified nano-titanium dioxide in a 1:1 mass ratio; Modified nano-titanium dioxide 3 (TiO2-M3): A mixture formed by first modified nano-titanium dioxide 2 and second modified nano-titanium dioxide in a mass ratio of 1:2; Modified nano-titanium dioxide 4 (TiO2-M4): A mixture formed by first modified nano-titanium dioxide 1 and third modified nano-titanium dioxide in a mass ratio of 1:2; Modified nano-titanium dioxide 5 (TiO2-M5): A mixture formed by first modified nano-titanium dioxide 1 and fourth modified nano-titanium dioxide in a mass ratio of 1:2; Modified nano-titanium dioxide 6 (TiO2-M6): A mixture formed by second modified nano-titanium dioxide and third modified nano-titanium dioxide in a mass ratio of 1:2; Modified nano-titanium dioxide 7 (TiO2-M7): The second type of modified nano-titanium dioxide; Modified nano-titanium dioxide 8 (TiO2-M8): The fourth type of modified nano-titanium dioxide; Nano titanium dioxide (TiO2-1): Anatase titanium dioxide, CR210+, Jinzhou Titanium Industry; Nano titanium dioxide (TiO2-2): Rutile nano titanium dioxide, R-320, Solvay; Processing aid: calcium stearate, commercially available.

[0069] First modified nano-titanium dioxide 1: comprises nano-titanium dioxide and a coating layer disposed on at least a portion of the surface of the nano-titanium dioxide, the coating layer comprising cerium dioxide; in the first modified nano-titanium dioxide 1, the mass percentage of nano-titanium dioxide is 90%; the preparation method of the first modified nano-titanium dioxide 1 includes the following steps: S1. Disperse 100g of nano TiO2 (rutile nano-titanium dioxide) in deionized water (solid content 10%) and treat it with ultrasound for 45min to ensure full dispersion and obtain a stable suspension. S2. Add the calculated amount of 28g of cerium nitrate hexahydrate (Ce(NO3)3·6H2O) and excess urea (the molar ratio of urea to Ce in cerium nitrate hexahydrate is 10:1) to the above suspension and stir until completely dissolved. S3. Heat the reaction system to 90-95℃ and stir vigorously at this temperature (stirring speed 400 rpm) for 5 hours. S4. After the reaction is complete, stop heating, allow the system to cool naturally and continue stirring and maturing for 1.5 hours, then filter and dry the obtained solid product in a vacuum drying oven at 90°C for 12 hours. S5. The dried powder is calcined in a muffle furnace at 450°C for 3 hours to obtain the first modified nano titanium dioxide 1, wherein the mass percentage of nano titanium dioxide in the first modified nano titanium dioxide 1 is 90%.

[0070] The first modified nano-titanium dioxide 2 comprises nano-titanium dioxide and a coating layer disposed on at least a portion of the surface of the nano-titanium dioxide, the coating layer comprising cerium dioxide; in the first modified nano-titanium dioxide 1, the mass percentage of nano-titanium dioxide is 95%; the difference between the preparation method of the first modified nano-titanium dioxide 2 and the preparation method of the first modified nano-titanium dioxide 1 lies in adjusting the amount of cerium nitrate hexahydrate added, so that the mass percentage of nano-titanium dioxide in the subsequently prepared second modified nano-titanium dioxide 2 is 95%.

[0071] The second modified nano-titanium dioxide comprises nano-titanium dioxide and a coating layer disposed on at least a portion of the surface of the nano-titanium dioxide, the coating layer comprising silicon dioxide; in the second modified nano-titanium dioxide 1, the mass percentage of nano-titanium dioxide is 90%; the preparation method of the second modified nano-titanium dioxide includes the following steps: 100g of nano-TiO2 (rutile nano-titanium dioxide) was dispersed in deionized water (solid content 10%) and ultrasonically treated for 45min to ensure full dispersion and obtain a stable suspension. Then, a measured amount of sodium silicate was added, and the initial pH was adjusted to 9 with ammonia. The mixture was then stirred and matured at 70℃ for 1.5h, followed by cooling, filtration, collection and washing of the solid. The solid was then calcined in a muffle furnace at 450℃ for 3h to obtain the second modified nano-titanium dioxide, wherein the mass percentage of nano-titanium dioxide in the modified nano-titanium dioxide was 90%.

[0072] The third modified nano-titanium dioxide comprises nano-titanium dioxide and a coating layer disposed on at least a portion of the surface of the nano-titanium dioxide, the coating layer comprising zirconium dioxide; in the third modified nano-titanium dioxide, the mass percentage of nano-titanium dioxide is 90%; the difference between the preparation method of the third modified nano-titanium dioxide and the preparation method of the first modified nano-titanium dioxide 1 is that zirconium oxychloride is used instead of cerium nitrate hexahydrate.

[0073] The fourth modified nano-titanium dioxide comprises nano-titanium dioxide and a coating layer disposed on at least a portion of the surface of the nano-titanium dioxide, the coating layer comprising cerium dioxide; in the first modified nano-titanium dioxide 1, the mass percentage of nano-titanium dioxide is 90%; the preparation method of the first modified nano-titanium dioxide 1 includes the following steps: 100g of nano-titanium dioxide (rutile nano-titanium dioxide) was dried in a vacuum oven at 100℃ and then placed in a flask. Dichloromethane was added and ultrasonic treatment was performed to form a uniform and stable suspension (solid content of 10%). The temperature was controlled at 70℃, and 14.5g of toluene-2,4-diisocyanate (TDI) was slowly added to the stirred TiO2 suspension. The mixture was refluxed for 6 hours, then washed and dried to obtain the fourth modified nano-titanium dioxide, in which the mass percentage of nano-titanium dioxide was 90%.

[0074] Examples 1-14 and Comparative Examples 1-8 The present invention provides a polypropylene composition in the embodiments and comparative examples, wherein the component content (parts by weight) of the polypropylene composition is shown in Tables 1-2; Table 1 Table 2 The method for preparing the polypropylene composition provided in Example 1 is as follows: After the components are mixed evenly, they are added to a twin-screw extruder for melt mixing. The feed section temperature is set to 180℃, the melt section temperature to 210℃, the mixing section melt temperature to 210℃, the die temperature to 210℃, the screw length-to-diameter ratio to 48:1, single vacuum extraction, screw speed to 400 rpm, and the main feed port feeding speed to 400 Kg / h, to obtain a polypropylene composition.

[0075] The preparation methods of the polypropylene compositions provided in Examples 2-14 and Comparative Examples 1-8 are consistent with those in Example 1, except that the relevant components are not required.

[0076] Example of effect The performance of the polypropylene compositions prepared in the examples and comparative examples of this invention is verified by the following aspects: The polypropylene compositions prepared in the examples and comparative examples were injection molded into standard specimens (tensile strength specimens: dumbbell shape, 170mm long, 10mm wide, and 4.0mm thick; flexural strength specimens: 80mm long, 10mm wide, and 4.0mm thick); impact specimens: 80mm long, 10mm wide, and 4.0mm thick; color difference specimens: 50mm long, 50mm wide, and 4.0mm thick). Specifically, the injection molding machine model was Bochuang BS320-III, and the injection conditions were: injection temperature 200℃ across the entire range; injection pressure 70% across the entire range; holding pressure 70% across the entire range; holding time 15s; and cooling time 8s. The injection-molded stencils were then tested. Tensile strength: Tested according to ISO 527-2025; Bending strength: Tested according to ISO 178-2019; Impact strength: Tested according to ISO 180-2023; Color difference: Color difference ΔE was tested according to ASTM D 1003 / CIE lab. First, set the tensile strength, flexural strength, impact strength, and color of the initial sample after injection molding; then place the sample in a UV-C (254nm) environment for 450h, and then take out the sample after light exposure to test the tensile strength, flexural strength, impact strength, and color; calculate the retention rate of tensile strength, flexural strength, and impact strength before and after light exposure. The results of the above tests are shown in Table 3. Table 3 As can be seen from Table 3, the modified nano-titanium dioxide introduced in this invention maintains good UV-C shielding while effectively controlling photocatalytic damage by capturing free radicals through light stabilizers. Combined with the formulation of UV absorbers and antioxidants, it achieves a comprehensive effect of shielding, absorption, and capture. When the technical solution of this invention is adopted, the resulting polypropylene composition exhibits good UV resistance and excellent mechanical properties; specifically, the tensile strength of the obtained polypropylene composition is above 35.2 MPa, and after light irradiation, the tensile strength retention rate is above 65%; ΔE is below 1.8. As can be seen from Examples 1-3 and Comparative Example 8, when the amount of modified nano-titanium dioxide added in Comparative Example 8 is too large, the tensile strength of the obtained product decreases significantly. As can be seen from Examples 1 and Comparative Examples 6-7, none of the components provided by the present invention can be omitted. When no light stabilizer is added in Comparative Example 6, the tensile strength retention rate of the obtained product after light irradiation is significantly reduced, and ΔE is significantly increased. When no modified nano titanium dioxide is added in Comparative Example 7, the tensile strength retention rate of the obtained product is significantly reduced, and ΔE is significantly increased. As can be seen from Examples 1, 10-14, and Comparative Examples 2-5, whether or not nano-titanium dioxide is coated or organically modified, and the specific type selected, affects the overall performance of the product. When uncoated nano-titanium dioxide is used in Comparative Examples 4-5, the product absorbs UV-C energy while undergoing photocatalytic degradation, resulting in substandard tensile strength retention and color difference. When the type of modified nano-titanium dioxide in Comparative Examples 2-3 is not within the scope of this invention, the product also fails to meet the standards for tensile strength retention and color difference. As can be seen from Examples 1, 6-8 and Comparative Example 1, the type of UV absorber also affects the overall performance of the product. When the UV absorber used in Comparative Example 1 is not the type provided by this invention, the tensile strength retention rate and color difference of the obtained product are unqualified.

[0077] Finally, it should be noted that the above embodiments are used to illustrate the technical solutions of the present invention and not to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A polypropylene composition, characterized in that, The polypropylene composition comprises the following components in parts by weight: 68-92 parts polypropylene resin, 8-32 parts inorganic filler, 0.05-0.6 parts antioxidant, 0.1-1 part UV absorber, 0.05-0.6 parts light stabilizer, 0.1-0.6 parts modified nano titanium dioxide; The ultraviolet absorber includes triazine ultraviolet absorbers; The modified nano-titanium dioxide includes at least two of the following: first modified nano-titanium dioxide, second modified nano-titanium dioxide, third modified nano-titanium dioxide, and fourth modified nano-titanium dioxide. The first modified nano-titanium dioxide includes nano-titanium dioxide and a coating layer disposed on at least a portion of the surface of the nano-titanium dioxide, the coating layer including cerium dioxide; The second modified nano-titanium dioxide includes nano-titanium dioxide and a coating layer disposed on at least a portion of the surface of the nano-titanium dioxide, the coating layer including silicon dioxide; The third modified nano-titanium dioxide includes nano-titanium dioxide and a coating layer disposed on at least a portion of the surface of the nano-titanium dioxide, the coating layer including zirconium dioxide; The fourth modified nano-titanium dioxide is nano-titanium dioxide that has been surface-treated with diisocyanate compounds.

2. The polypropylene composition according to claim 1, characterized in that, The polypropylene composition comprises the following components in parts by weight: 75-85 parts polypropylene resin, 20-25 parts inorganic filler, 0.2-0.4 parts antioxidant, 0.4-0.6 parts ultraviolet absorber, 0.2-0.4 parts light stabilizer, and 0.3-0.4 parts modified nano titanium dioxide.

3. The polypropylene composition according to claim 1, characterized in that, The melt flow index of the polypropylene resin at 230℃ / 2.16kg is 8-32g / 10min.

4. The polypropylene composition according to claim 1, characterized in that, The modified nano-titanium dioxide contains 88-97% nano-titanium dioxide by mass.

5. The polypropylene composition according to claim 1, characterized in that, The ultraviolet absorber also includes benzotriazole ultraviolet absorbers; preferably, the mass ratio of the triazine ultraviolet absorber to the benzotriazole ultraviolet absorber is (1-4):

1.

6. The polypropylene composition according to claim 1, characterized in that, The modified nano-titanium dioxide includes a first modified nano-titanium dioxide, wherein the mass percentage of the first modified nano-titanium dioxide is 30-60% based on the mass of the modified nano-titanium dioxide.

7. The polypropylene composition according to claim 5, characterized in that, The inorganic filler includes at least one of talc, mica, and barium sulfate; And / or, the antioxidant includes hindered phenolic antioxidants; And / or, the triazine UV absorber includes at least one of 2,4,6-tris(2′-hydroxy4′-n-butoxyphenyl) and 2,4-di(4-biphenyl)-6-(2,4-dihydroxy)phenyl-1,3,5-triazine; And / or, the benzotriazole UV absorber includes at least one of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, and 2-(2'-hydroxy-3',5'-di-tert-pentylphenyl)benzotriazole; And / or, the light stabilizer includes a hindered amine light stabilizer.

8. The polypropylene composition according to claim 1, characterized in that, The polypropylene composition also includes 0.2-0.5 parts of processing aids.

9. The method for preparing the polypropylene composition according to any one of claims 1-8, characterized in that, The preparation method includes the following steps: After the components are mixed evenly, they are melt-blended and then extruded and granulated to obtain a polypropylene composition.

10. A component, characterized in that, The component is prepared using the polypropylene composition as described in any one of claims 1-8.

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