Core-shell structure functional microsphere, nylon material as well as preparation method and application of core-shell structure functional microsphere and nylon material

Abstract

The invention relates to the technical field of high polymer materials, and discloses a core-shell structure functional microsphere, a nylon material and a preparation method and application thereof. The core-shell structure functional microsphere comprises an inner core containing an ultraviolet light absorber and a shell layer coating the surface of the inner core, and the shell layer is of a hybrid network structure of polysiloxane and silicon dioxide. According to the invention, the core-shell structure functional microspheres and nylon resin are subjected to melt blending, the integration of dual functions of weather resistance and wear resistance is realized at an extremely low addition amount (0.1 wt%-1.0 wt%), the color difference is less than 2.0 after ultraviolet irradiation aging for 360 hours, the color difference is less than 0.8 after cross scraping, and the performance is far better than that of a traditional system needing to add a common UV agent with the same or higher dosage; besides, the technology is completely compatible with the existing twin-screw extrusion and injection molding process, the complicated secondary coating spraying step with high energy consumption and high VOC emission is omitted, and the comprehensive production cost and environmental pollution are remarkably reduced.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a core-shell structured functional microsphere, nylon material, its preparation method and application. Background Technology

[0002] Nylon (polyamide), as an important type of engineering plastic, is widely used in automotive parts, electronic and electrical housings, outdoor structural components and other fields due to its excellent mechanical strength, chemical corrosion resistance and good processing and molding properties.

[0003] However, the amide groups in nylon molecular chains are extremely sensitive to ultraviolet light. Under sunlight or artificially accelerated aging conditions (such as xenon lamps), ultraviolet light easily induces the breakage and oxidation of nylon molecular chains, leading to decreased impact toughness, surface cracking, and color drift, severely limiting its application in scenarios requiring long-term outdoor stability. Existing technologies generally improve weather resistance by adding small-molecule ultraviolet absorbers (UVA) or hindered amine light stabilizers (HALS), but these small-molecule additives are prone to thermal decomposition and volatilization loss at the high processing temperatures of nylon. More importantly, during the use of the product, due to limited compatibility with the nylon matrix and the thermal motion of the molecular chains, they continuously migrate to the material surface and are eventually washed away by rainwater, condensation, or wiping solvents. To ensure that the product maintains acceptable color difference (e.g., ΔE ≤ 3.0) after thousands of hours of aging, the amount of UVA added needs to be significantly increased to 2wt%-3wt% or even higher. This not only significantly increases costs, but also reduces the tensile and impact mechanical properties of the nylon matrix itself, and causes problems such as mold contamination and sticky product surfaces during injection molding, affecting production efficiency and product appearance.

[0004] Furthermore, nylon materials have a low surface modulus, making them highly susceptible to scratches and abrasions during assembly, transportation, daily cleaning, or contact with sand, gravel, or metal tools, resulting in noticeable stress whitening. This not only damages the product's appearance but also severely affects the adhesion of coatings for parts requiring subsequent painting or electroplating. The current mainstream solution is to coat the surface of injection-molded nylon products with a polyurethane (PU) or ultraviolet (UV) cured wear-resistant coating. However, this process requires expensive painting production lines, drying ovens, and VOC exhaust gas treatment devices, making the process complex and energy-intensive. Moreover, due to the significant difference in thermal expansion coefficients between the organic coating and the nylon substrate, internal stress can easily develop at the interface after exposure to ambient temperature cycling, leading to paint film cracking, peeling, or even flaking, raising concerns about reliability.

[0005] Microencapsulation technology has been explored for encapsulating UVA to inhibit the migration and volatilization of small-molecule UVA. However, existing microencapsulation systems, such as those using melamine-formaldehyde resin or pure inorganic silica as shell materials, typically exhibit high rigidity, brittleness, and glass transition temperatures. During the screw extrusion process of nylon materials, these shells are easily crushed by the intense screw shear forces, leading to encapsulation failure. Furthermore, the overly dense inorganic silica shell, while trapping UVA, also severely hinders the necessary, slow diffusion of UVA to the surface of the material where it needs to function, resulting in insufficient actual protective concentration and compromised weather resistance. More importantly, these traditional functional microcapsule designs are singular, focusing solely on solving weather resistance issues and failing to simultaneously impart scratch resistance to the material surface, thus failing to achieve multifunctional integration. Summary of the Invention

[0006] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. Therefore, one objective of the present invention is to provide a core-shell structured functional microsphere.

[0007] The second objective of this invention is to provide a method for preparing such core-shell structured functional microspheres.

[0008] The third objective of this invention is to provide applications for such core-shell structured functional microspheres.

[0009] The fourth objective of this invention is to provide a nylon material.

[0010] The fifth objective of this invention is to provide a method for preparing this nylon material.

[0011] The sixth object of this invention is to provide applications of this nylon material.

[0012] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A first aspect of the present invention provides a core-shell structured functional microsphere comprising a core containing an ultraviolet absorber and a shell covering the surface of the core, the shell being a hybrid network structure of polysiloxane and silicon dioxide.

[0013] In some embodiments of the present invention, the functionalized microspheres comprise the following raw materials: polysiloxane, alkoxysilane, ultraviolet absorber, alkaline catalyst, and surfactant.

[0014] In some embodiments of the present invention, the molecular weight of the polysiloxane is 20,000-30,000 Da.

[0015] In some embodiments of the present invention, the alkoxysilane is selected from at least one of tetraethyl orthosilicate, methyl orthosilicate, and isopropyl orthosilicate.

[0016] In some preferred embodiments of the present invention, the alkoxysilane is tetraethyl orthosilicate.

[0017] In some embodiments of the present invention, the ultraviolet absorber includes at least one of triazine, benzotriazole, and benzophenone ultraviolet absorbers.

[0018] In some preferred embodiments of the present invention, the ultraviolet absorber is selected from at least one of bis(ethylhexyloxyphenol)methoxyphenyltriazine and octyltriazine ketone.

[0019] In some embodiments of the present invention, the alkaline catalyst is selected from ammonia or organic amines.

[0020] In some embodiments of the present invention, the organic amine is selected from at least one of ethylenediamine and triethylamine.

[0021] In some preferred embodiments of the present invention, the alkaline catalyst is ammonia water with a concentration of 20wt%-30wt%.

[0022] In some embodiments of the present invention, the surfactant is selected from at least one of Tween, alkylphenol polyoxyethylene ether, and block polyether.

[0023] In some preferred embodiments of the present invention, the surfactant is selected from at least one of Tween-80, octylphenol polyoxyethylene ether-10, and poloxamer.

[0024] A second aspect of the present invention provides a method for preparing the core-shell structured functional microspheres described in the first aspect of the present invention, comprising the following steps: S1. Polysiloxane, alkoxysilane, and ultraviolet absorber are dissolved in solvent I to form an oil phase; surfactant is mixed with solvent II to form an aqueous phase; S2. Add the oil phase to the aqueous phase, homogenize and emulsify to obtain an emulsified system; S3. Add an alkaline catalyst to the emulsion system and react to obtain the core-shell structured functional microspheres. Solvent I is selected from organic solvents with a boiling point below 100°C and that are immiscible with water; solvent II is selected from aqueous solutions of C1-C4 alkanols.

[0025] In some embodiments of the present invention, solvent I is selected from at least one of dichloromethane and ethyl acetate.

[0026] In some preferred embodiments of the present invention, solvent I is dichloromethane.

[0027] In some embodiments of the present invention, the concentration of C1-C4 alkanol in solvent II is 10wt%-30wt%.

[0028] In some preferred embodiments of the present invention, solvent II is an aqueous solution of ethanol.

[0029] In some embodiments of the present invention, in step S1, the mass ratio of the polysiloxane, alkoxysilane, ultraviolet absorber and solvent I is 1: (0.8-1.2): (1-1.5): (10-30).

[0030] In some preferred embodiments of the present invention, in step S1, the mass ratio of the polysiloxane, alkoxysilane, ultraviolet absorber and solvent I is 1: (0.9-1.1): (1-1.2): (10-20).

[0031] In some embodiments of the present invention, in step S1, the content of the surfactant in the aqueous phase is 0.5wt%-1.5wt%.

[0032] In some preferred embodiments of the present invention, in step S1, the content of the surfactant in the aqueous phase is 0.8wt%-1.2wt%.

[0033] In some embodiments of the present invention, in step S2, the volume ratio of the aqueous phase to the oil phase is (5-10):1.

[0034] In some embodiments of the present invention, in step S2, the rotation speed of the homogenization emulsification is 12000-16000 rpm, and the time is 3-10 min.

[0035] In some embodiments of the present invention, in step S3, the concentration of the alkaline catalyst is 20wt%-30wt%; the volume ratio of the alkaline catalyst to the emulsion system is 1:(10-20).

[0036] In some embodiments of the present invention, in step S3, the reaction temperature is 25-35°C and the time is 1-3 hours.

[0037] In some embodiments of the present invention, in step S3, the reaction is carried out under water bath and stirring conditions, wherein the stirring speed is 500-600 rpm.

[0038] In some embodiments of the present invention, after the reaction is completed in step S3, the process further includes rotary evaporation to remove solvent I, solid-liquid separation to collect the solid phase, washing, and drying to obtain the core-shell structured functional microspheres.

[0039] In some embodiments of the present invention, the rotary evaporation temperature is 40-60°C and the vacuum degree is -0.04 to -0.08 MPa.

[0040] In some embodiments of the present invention, the solid-liquid separation method includes centrifugation.

[0041] In some embodiments of the present invention, the washing includes washing with water and ethanol 2-4 times each.

[0042] In some embodiments of the present invention, the drying temperature is 80-120°C and the time is 20-25 hours.

[0043] Specifically, the method for preparing core-shell structured functional microspheres provided by this invention involves high-speed homogenization of an oil phase containing an ultraviolet absorber, high molecular weight polysiloxane (organic shell component), and alkoxysilane (inorganic shell precursor) in an aqueous phase containing a surfactant, forming numerous tiny oil droplets (O / W type emulsion). Each oil droplet uniformly dissolves all the raw materials that will form the future shell and core. When an alkaline catalyst is added to the emulsion system, the alkaline catalyst diffuses from the aqueous phase into the surface of the oil droplets. The alkoxysilane first reacts with water on the surface of the oil droplets, where the alkaline catalyst concentration is high, to generate silanols (Si-OH). The generated silanols are very reactive and will form an inorganic Si-O-Si (SiO2) network through condensation between silanols. They will also condense with the end groups or side groups of the polysiloxane, chemically grafting the flexible long chains of polysiloxane onto the microspheres. On the formed inorganic SiO2 network, the entire process begins at the surface of the oil droplet and gradually progresses into the interior. Since the reaction takes place on the oil phase side while the alkaline catalyst is supplied from the aqueous phase side, the most vigorous reaction and the highest degree of cross-linking occur on the surface of the oil droplet. Ultimately, a dense, chemically hybridized cross-linked network shell of polysiloxane and silica is formed on the surface of the oil droplet, encapsulating the internal oil phase (containing the remaining alkoxysilane, polysiloxane, and UV absorber). As the reaction proceeds, the shell continuously thickens and solidifies. The hydrophobic UV absorber, due to its affinity for the oil phase, is effectively confined within the hybrid shell composed of the hydrophobic polysiloxane and silica network. Subsequent rotary evaporation to remove the solvent, washing, and drying processes remove moisture and other volatiles, allowing this core-shell structure to finally solidify into dry microsphere powder.

[0044] The third aspect of the present invention provides the application of the core-shell structured functional microspheres described in the first aspect of the present invention in the preparation of polymer composite materials.

[0045] In some embodiments of the present invention, the polymer composite material includes polyolefin composite material, polyester composite material, polycarbonate composite material, and nylon composite material.

[0046] A fourth aspect of the present invention provides a nylon material comprising the core-shell structured functional microspheres described in the first aspect of the present invention.

[0047] In some embodiments of the present invention, the nylon material comprises, by weight percentage, the following raw materials: 98.5%-99% nylon resin, 0.1%-1.0% core-shell structured functional microspheres, 0.1%-0.5% antioxidant, and 0.2%-0.8% lubricant.

[0048] In some embodiments of the present invention, the nylon resin is selected from at least one of nylon 6 and nylon 66.

[0049] In some embodiments of the present invention, the antioxidant is selected from at least one of hindered phenolic antioxidants and phosphite antioxidants.

[0050] In some preferred embodiments of the present invention, the antioxidant is a compound of hindered phenolic antioxidant and phosphite antioxidant in a mass ratio of 1:(0.8-1.2).

[0051] In some embodiments of the present invention, the hindered phenolic antioxidant is selected from N,N'-1,6-hexylene-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide] (antioxidant 1098), 2,6 di-tert-butyl-p-methylphenol (BHT), β (3,5 Second Uncle Ding Ji 4 Octadecyl hydroxyphenyl propionate (antioxidant 1076), tetra[β-hydroxyphenyl]prop ... (3,5) Second Uncle Ding Ji 4 [Hydroxyphenyl]propionate] pentaerythritol ester (antioxidant 1010), triethylene glycol bis[β] (3 tert-butyl 4 hydroxyl 5 At least one of [methylphenyl]propionate (antioxidant 245).

[0052] In some embodiments of the present invention, the phosphite antioxidant is selected from tri[2,4]... At least one of the following: di-tert-butylphenyl phosphite (antioxidant 168), bisphenol A phosphite, triphenyl phosphite (TPP), and diphenylisooctyl phosphite (ODPP).

[0053] In some embodiments of the present invention, the lubricant is selected from at least one of zinc stearate, calcium stearate, ethylene bis-stearamide, and polyethylene wax.

[0054] The fifth aspect of the present invention provides a method for preparing the nylon material described in the fourth aspect of the present invention, comprising the following steps: The raw materials are mixed and melt-blended using a twin-screw extruder, then extruded and granulated to obtain the nylon material.

[0055] In some embodiments of the present invention, the processing temperature of each zone of the twin-screw extruder is 210-260°C; the screw speed is 250-300 rpm.

[0056] The sixth aspect of the present invention provides the application of the nylon material described in the fourth aspect of the present invention in the manufacture of automotive parts, photovoltaic modules, electronic and electrical housings or outdoor structural components.

[0057] Compared with the prior art, the beneficial effects of the present invention are: This invention provides a core-shell structured functional microsphere with a polysiloxane hybrid silica shell coated with a UV absorber. This microsphere is melt-blended with nylon resin, achieving a dual function of weather resistance and abrasion resistance with extremely low addition levels (0.1wt%-1.0wt%). After 360 hours of UV aging, the color difference is less than 2.0, and after cross-scraping, the color difference is less than 0.8. Its performance far surpasses traditional systems that require the addition of equal or higher doses of ordinary UV agents. Furthermore, this technology is fully compatible with existing twin-screw extrusion and injection molding processes, eliminating the complex, energy-intensive, and VOC-emitting secondary spray coating step, significantly reducing overall production costs and environmental pollution. The resulting nylon material, while maintaining unchanged mechanical properties, possesses excellent long-term outdoor weather resistance and surface scratch resistance, providing a high-performance, low-cost, and environmentally friendly nylon material for durable outdoor components in the automotive, photovoltaic, and electronics industries. Attached Figure Description

[0058] Figure 1 The diagram shows the structure of the core-shell functional microspheres prepared in the examples, as well as the principle diagram of the scratch resistance and UV resistance of nylon material. Detailed Implementation

[0059] The present invention will be further described in detail below through specific embodiments. Unless otherwise specified, the raw materials, reagents, or apparatus used in the embodiments and comparative examples are all available from conventional commercial sources or can be obtained by existing technical methods. Unless otherwise specified, the test or experimental methods are conventional methods in the art.

[0060] Example 1 This embodiment prepares a core-shell structured functional microsphere and uses it in the preparation of nylon materials. The steps are as follows: Preparation of core-shell structured functional microspheres: S11. Add 8g of diethylhexyloxyphenol methoxyphenyl triazine, 4g of octyl triazine ketone, 10g of polysiloxane (20000Da) and 10g of tetraethyl orthosilicate to 150g of dichloromethane, and stir at 23°C to dissolve and form a uniform, transparent yellow solution or a transparent solution, thus obtaining the oil phase. S12. Add 200g of anhydrous ethanol to 800g of deionized water, then add 10g of Tween-80 and stir to form a uniform colorless and transparent solution to obtain the aqueous phase. S21. Pour the oil phase into the aqueous phase (aqueous phase: oil phase = 10: 1, v / v), and perform homogenization and emulsification treatment using a high-speed homogenizer at a speed of 13000 rpm for 5 min to obtain the emulsion system. S31. Add 25wt% ammonia water (ammonia water: emulsion system = 1: 15, v / v) to the emulsion system and stir in a constant temperature water bath at 30℃ for 2 hours. After the reaction is complete, remove the residual dichloromethane in the resulting solution by rotary evaporation at a temperature of 45℃ and a negative pressure of -0.06MPa. Separate the resulting suspension by centrifugation at a speed of 10000rpm for 30 minutes. Wash the resulting solid powder three times each with ethanol and deionized water, and then bake it in a convection oven at 100℃ for 24 hours to obtain core-shell structured functional microspheres, denoted as core-shell structured functional microspheres-Ⅰ.

[0061] Preparation of nylon materials: 99wt% nylon 6, 0.5wt% core-shell structured functional microspheres-I, 0.1wt% antioxidant 1098, 0.1wt% antioxidant 168, and 0.3wt% ethylene bis-stearamide were mixed and blended in a twin-screw extruder for modification. The processing temperature in each zone of the twin-screw extruder was 210-230℃, and the screw speed was 300rpm. After the extruder strands were cooled by water, they were pelletized to obtain nylon material.

[0062] Example 2 This embodiment prepares a core-shell structured functional microsphere and uses it in the preparation of nylon materials. The steps are as follows: Preparation of core-shell structured functional microspheres: S11. Add 4g of diethylhexyloxyphenol methoxyphenyl triazine, 1g of octyltriazine ketone, 5g of polysiloxane (23000Da) and 5g of tetraethyl orthosilicate to 100g of dichloromethane, stir at 23°C to dissolve and form a uniform, transparent yellow solution or a transparent solution, and obtain the oil phase. S12. Add 250g of anhydrous ethanol to 1000g of deionized water, then add 12.5g of Tween-80 and stir to form a uniform colorless and transparent solution to obtain the aqueous phase. S21. Pour the oil phase into the aqueous phase (aqueous phase: oil phase = 10: 1, v / v), and perform homogenization and emulsification treatment using a high-speed homogenizer at a speed of 16000 rpm for 8 minutes to obtain the emulsion system. S31. Add 25wt% ammonia water (ammonia water: emulsion system = 1: 10, v / v) to the emulsion system and stir in a constant temperature water bath at 30℃ for 2 hours. After the reaction is complete, remove the residual dichloromethane in the resulting solution by rotary evaporation at a temperature of 50℃ and a negative pressure of -0.06MPa. Separate the resulting suspension by centrifugation at a speed of 10000rpm for 30 minutes. Wash the resulting solid powder three times each with ethanol and deionized water, and then bake it in a convection oven at 100℃ for 24 hours to obtain core-shell structured functional microspheres, denoted as core-shell structured functional microspheres-II.

[0063] Preparation of nylon materials: 98.8 wt% nylon 6, 0.7 wt% core-shell structured functional microspheres-II, 0.1 wt% antioxidant 1098, 0.1 wt% antioxidant 168, and 0.3 wt% ethylene bis-stearamide were mixed and blended in a twin-screw extruder for modification. The processing temperature in each zone of the twin-screw extruder was 210-230℃, and the screw speed was 300 rpm. After the extruder strands were cooled by water, they were pelletized to obtain nylon material.

[0064] Example 3 This embodiment prepares a core-shell structured functional microsphere and uses it in the preparation of nylon materials. The steps are as follows: Preparation of core-shell structured functional microspheres: S11. Add 6g of diethylhexyloxyphenol methoxyphenyl triazine, 2g of octyl triazine ketone, 8g of polysiloxane (25000Da) and 8g of tetraethyl orthosilicate to 80g of dichloromethane, stir and dissolve at 23°C to form a uniform transparent yellow solution or a transparent solution, and obtain the oil phase. S12. Add 200g of anhydrous ethanol to 800g of deionized water, then add 10g of Tween-80 and stir to form a uniform colorless and transparent solution to obtain the aqueous phase. S21. Pour the oil phase into the aqueous phase (aqueous phase: oil phase = 10: 1, v / v), and perform homogenization and emulsification treatment using a high-speed homogenizer at a speed of 14000 rpm for 6 minutes to obtain the emulsion system. S31. Add 25wt% ammonia water (ammonia water: emulsion system = 1: 12, v / v) to the emulsion system and stir in a constant temperature water bath at 30℃ for 2 hours. After the reaction is complete, remove the residual dichloromethane in the resulting solution by rotary evaporation at a temperature of 50℃ and a negative pressure of -0.06MPa. Separate the resulting suspension by centrifugation at a speed of 10000rpm for 30 minutes. Wash the resulting solid powder three times each with ethanol and deionized water, and then bake it in a convection oven at 100℃ for 24 hours to obtain core-shell structured functional microspheres, denoted as core-shell structured functional microspheres-III.

[0065] Preparation of nylon materials: 98.5 wt% nylon 6, 1.0 wt% core-shell structured functional microspheres-III, 0.1 wt% antioxidant 1098, 0.1 wt% antioxidant 168, and 0.3 wt% ethylene bis-stearamide were mixed and blended in a twin-screw extruder for modification. The processing temperature in each zone of the twin-screw extruder was 210-230℃, and the screw speed was 300 rpm. After the extruder strands were cooled by water, they were pelletized to obtain nylon material.

[0066] Example 4 This embodiment prepares a core-shell structured functional microsphere and uses it in the preparation of nylon materials. The steps are as follows: Preparation of core-shell structured functional microspheres: S11. Add 8g of diethylhexyloxyphenol methoxyphenyl triazine, 4g of octyltriazine ketone, 10g of polysiloxane (28000Da) and 10g of tetraethyl orthosilicate to 150g of dichloromethane, and stir at 23°C to dissolve and form a uniform, transparent yellow solution or a transparent solution, thus obtaining the oil phase. S12. Add 200g of anhydrous ethanol to 800g of deionized water, then add 10g of Tween-80 and stir to form a uniform colorless and transparent solution to obtain the aqueous phase. S21. Pour the oil phase into the aqueous phase (aqueous phase: oil phase = 10: 1, v / v), and perform homogenization and emulsification treatment using a high-speed homogenizer at a speed of 13000 rpm for 5 min to obtain the emulsion system. S31. Add 25wt% ammonia water (ammonia water: emulsion system = 1: 15, v / v) to the emulsion system and stir in a constant temperature water bath at 30℃ for 2 hours. After the reaction is complete, remove the residual dichloromethane in the resulting solution by rotary evaporation at a temperature of 45℃ and a negative pressure of -0.06MPa. Separate the resulting suspension by centrifugation at a speed of 10000rpm for 30 minutes. Wash the resulting solid powder three times each with ethanol and deionized water, and then bake it in a convection oven at 100℃ for 24 hours to obtain core-shell structured functional microspheres, denoted as core-shell structured functional microspheres-Ⅳ.

[0067] Preparation of nylon materials: 98.8 wt% nylon 66, 0.7 wt% core-shell structured functional microspheres-Ⅳ, 0.1 wt% antioxidant 1098, 0.1 wt% antioxidant 168, and 0.3 wt% ethylene bis-stearamide were mixed and blended in a twin-screw extruder for modification. The processing temperature in each zone of the twin-screw extruder was 245-260℃, and the screw speed was 300 rpm. After the extruder strands were cooled by water, they were pelletized to obtain nylon material.

[0068] Example 5 This embodiment prepares a core-shell structured functional microsphere and uses it in the preparation of nylon materials. The steps are as follows: Preparation of core-shell structured functional microspheres: S11. Add 4g of diethylhexyloxyphenol methoxyphenyl triazine, 1g of octyltriazine ketone, 5g of polysiloxane (30000Da) and 5g of tetraethyl orthosilicate to 100g of dichloromethane, and stir at 23°C to dissolve and form a uniform, transparent yellow solution or a transparent solution, thus obtaining the oil phase. S12. Add 250g of anhydrous ethanol to 1000g of deionized water, then add 10g of Tween-80 and stir to form a uniform colorless and transparent solution to obtain the aqueous phase. S21. Pour the oil phase into the aqueous phase (aqueous phase: oil phase = 10: 1, v / v), and perform homogenization and emulsification treatment using a high-speed homogenizer at a speed of 16000 rpm for 8 minutes to obtain the emulsion system. S31. Add 25wt% ammonia water (ammonia water: emulsion system = 1: 10, v / v) to the emulsion system and stir in a constant temperature water bath at 30℃ for 2 hours. After the reaction is complete, remove the residual dichloromethane in the resulting solution by rotary evaporation at a temperature of 50℃ and a negative pressure of -0.06MPa. Separate the resulting suspension by centrifugation at a speed of 10000rpm for 30 minutes. Wash the resulting solid powder three times each with ethanol and deionized water, and then bake it in a convection oven at 100℃ for 24 hours to obtain core-shell structured functional microspheres, denoted as core-shell structured functional microspheres-V.

[0069] Preparation of nylon materials: 98.5 wt% nylon 66, 1.0 wt% core-shell structured functional microspheres-V, 0.1 wt% antioxidant 1098, 0.1 wt% antioxidant 168, and 0.3 wt% ethylene bis-stearamide were mixed and blended in a twin-screw extruder for modification. The processing temperature in each zone of the twin-screw extruder was 245-260℃, and the screw speed was 300 rpm. After the extruder strands were cooled by water, they were pelletized to obtain nylon material.

[0070] Comparative Example 1 This comparative example prepares a nylon material using the following steps: 98.5 wt% nylon 6, 0.6 wt% bis(ethylhexyloxyphenol) methoxyphenyl triazine, 0.4 wt% octyltriazine ketone, 0.1 wt% antioxidant 1098, 0.1 wt% antioxidant 168, and 0.3 wt% ethylene bis-stearamide were mixed and blended in a twin-screw extruder. The processing temperature in each zone of the twin-screw extruder was 210-230℃, and the screw speed was 300 rpm. The extruder strands were cooled with water and then pelletized to obtain nylon material.

[0071] Comparative Example 2 This comparative example prepares a nylon material using the following steps: 98 wt% nylon 6, 1.0 wt% bis(ethylhexyloxyphenol) methoxyphenyl triazine, 0.5 wt% octyltriazine ketone, 0.1 wt% antioxidant 1098, 0.1 wt% antioxidant 168, and 0.3 wt% ethylene bis-stearamide were mixed and blended in a twin-screw extruder. The processing temperature in each zone of the twin-screw extruder was 210-230℃, and the screw speed was 300 rpm. After the extruder strands were cooled by water, they were pelletized to obtain nylon material.

[0072] Comparative Example 3 This comparative example prepares a nylon material using the following steps: 98.5 wt% nylon 66, 0.6 wt% bis(ethylhexyloxyphenol) methoxyphenyl triazine, 0.4 wt% octyltriazine ketone, 0.1 wt% antioxidant 1098, 0.1 wt% antioxidant 168, and 0.3 wt% ethylene bis-stearamide were mixed and blended in a twin-screw extruder. The processing temperature in each zone of the twin-screw extruder was 245-260℃, and the screw speed was 300 rpm. The extruder strands were cooled with water and then pelletized to obtain nylon material.

[0073] Comparative Example 4 This comparative example prepares a nylon material using the following steps: 98 wt% nylon 66, 1.0 wt% bis(ethylhexyloxyphenol) methoxyphenyl triazine, 0.5 wt% octyltriazine ketone, 0.1 wt% antioxidant 1098, 0.1 wt% antioxidant 168, and 0.3 wt% ethylene bis-stearamide were mixed and blended in a twin-screw extruder. The processing temperature in each zone of the twin-screw extruder was 245-260℃, and the screw speed was 300 rpm. The extruder strands were cooled with water and then pelletized to obtain nylon material.

[0074] Performance testing The nylon materials prepared in Examples 1-5 and Comparative Examples 1-4 were dried and then injection molded into standard test specimens. In Examples 1-3 and Comparative Examples 1 and 2, the processing temperature of each injection molding zone of the nylon materials was 220-235℃, the injection pressure was 30-60MPa, and the injection speed was 30-60%. In Examples 4 and 5 and Comparative Examples 3 and 4, the processing temperature of each injection molding zone of the nylon materials was 260-280℃, the injection pressure was 30-60MPa, and the injection speed was 30-60%.

[0075] The performance test items, reference standards, or test methods are as follows: 1. Density: Tested according to ASTM D792-20, "Standard Test Method for Density and Specific Gravity (Relative Density) of Plastics by Displacement"; 2. Tensile strength: Tested according to ASTM D638-22, "Standard Test Method for Tensile Properties of Plastics"; 3. Bending strength: Tested according to ASTM D790-17, "Standard Test Method for Bending Properties of Unreinforced and Reinforced Plastics and Electrical Insulators"; 4. Flexural modulus: Tested according to ASTM D790-17, "Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulators"; 5. Izod notched impact strength: Tested according to ASTM D256-24, "Standard Test Method for Determination of Impact Strength of Plastic Cantilever Pendulum". 6. Color difference due to light aging: Tested according to ISO 4892-3:2024 "Plastics - Laboratory light source exposure methods - Part 3: Fluorescent ultraviolet lamps", artificially accelerated weathering was performed using a UVA-340 lamp, with an irradiance of (0.76±0.02) W·m at 340 nm. -2 ·nm -1 The exposure period was 8 hours for drying (60±3℃) and 4 hours for condensation (50±3℃), with 30 cycles totaling 360 hours. The color change before and after was compared using a colorimeter, and the color difference was represented by △E1. 7. Scratch resistance: The cross-scratch method was used. The sample was scratched with a scratching head (1mm in diameter) with a load of 10N. The test speed was 1000 / min, the stroke was 40mm, and the spacing was 2mm. The lightness value E1 after the test was compared with the lightness value E0 before the test. The absolute value △E2=E1-E0 represents the scratch resistance. The conditioning conditions were 23±2℃, 50±5%RH, and 48h.

[0076] Table 1 Performance test results of nylon injection-molded specimens in Examples 1-5 and Comparative Examples 1-4

[0077] Table 1 shows the performance test results of the nylon material injection-molded specimens in Examples 1-5 and Comparative Examples 1-4. As can be seen from Table 1: In both Nylon 6 and Nylon 66 matrices, the addition of 0.5wt%-1.0wt% of core-shell functional microspheres in Examples 1-5, compared with Comparative Examples 1-4 which added the same or higher doses of ordinary UV agents, resulted in the materials maintaining the same level in terms of density, tensile strength, flexural strength, flexural modulus, and Izod notched impact strength, without significant fluctuations. This indicates that the core-shell functional microspheres introduced in this invention have good compatibility with the nylon matrix and, while achieving functionalization, do not negatively affect the basic mechanical properties of the material. In the nylon 6 system, the ΔE1 values ​​of Examples 1-3 (0.5wt%-1.0wt% of core-shell functional microspheres) were 1.82, 1.53, and 1.21, respectively, showing an improvement trend with increasing addition amount. In contrast, the ΔE1 values ​​of Comparative Examples 1-2 (1.0wt%-1.5wt% of ordinary UV agent) were 2.27 and 2.05, respectively, indicating that even with lower addition amounts than the comparative examples, the photoaging resistance of the examples was significantly better. In the nylon 66 system, the ΔE1 values ​​of Examples 4 and 5 (0.7wt%-1.0wt% of core-shell functional microspheres) were 1.92 and 1.74, also better than the 2.86 and 2.21 values ​​of Comparative Examples 3 and 4 (1.0wt%-1.5wt% of ordinary UV agent). The photoaging resistance of the nylon 6 matrix in the examples was generally better than that of nylon 66, which is related to the lower density of amide groups in nylon 6 and its slightly better photostability. In Examples 1-5, the nylon injection-molded samples all exhibited excellent scratch resistance, with ΔE2 of 0.45-0.71 for the nylon 6 system and 0.52-0.63 for the nylon 66 system. Furthermore, the scratch resistance improved with increasing amounts of core-shell functional microspheres. In contrast, the nylon injection-molded samples in Comparative Examples 1-4 showed no scratch resistance whatsoever. For both nylon 6 and nylon 66, ΔE2 was as high as 1.20-1.25, indicating that simply adding ordinary UV agents did not contribute to surface abrasion resistance. This demonstrates that the core-shell functional microspheres provided by this invention can simultaneously improve the UV aging resistance and scratch resistance of nylon materials. Down Figure 1 This is a schematic diagram of the core-shell structured functional microspheres prepared in the embodiments of this application, and a schematic diagram of the principle of scratch resistance and UV resistance of nylon material. Figure 1It is known that the core-shell structured functional microspheres consist of a core containing an ultraviolet absorber and a shell coating the surface of the core. This shell is a chemical hybrid network (PDMS-SiO2) of flexible high molecular weight polysiloxane (PDMS) and rigid silica (SiO2), which makes it both strong and elastic. During the cooling process after injection molding, due to the thermodynamic incompatibility between the polysiloxane segments and the nylon matrix, these segments spontaneously migrate to the surface. At the same time, under the shear force of the screw, the flexible microcapsules are flattened into a pancake shape and tend to align parallel to the product surface. Finally, a functional gradient layer is formed in the range of about 0-10 μm below the product surface: the outermost... The first layer consists of a high-hardness SiO2 network within the microcapsule shell, directly bearing the scratches and improving the surface pencil hardness and modulus. The middle layer uses polysiloxane segments as a backfill matrix. When scratching occurs, the high-hardness layer wears down preferentially, and then the soft polysiloxane flows and backfills the scratches, greatly reducing stress whitening caused by material deformation and light scattering. The inner layer stores UV absorbers, and the flexible shell allows the UV absorbers to diffuse slowly to the surface at a controlled rate, forming a concentration gradient from high to low from the inside out. This avoids the one-time burst release and rapid loss of small molecule additives and ensures that the material surface maintains an effective protective concentration during long-term use, thus achieving long-term resistance to UV aging.

Claims

1. A core-shell structured functional microsphere, characterized in that, It includes a core containing an ultraviolet absorber and a shell covering the surface of the core, the shell being a hybrid network structure of polysiloxane and silicon dioxide.

2. The functionalized microspheres according to claim 1, characterized in that, The functionalized microspheres comprise the following raw materials: polysiloxane, alkoxysilane, ultraviolet absorber, alkaline catalyst, and surfactant.

3. The functionalized microspheres according to claim 2, characterized in that, The molecular weight of the polysiloxane is 20,000-30,000 Da; And / or, the alkoxysilane is selected from at least one of tetraethyl orthosilicate, methyl orthosilicate, and isopropyl orthosilicate; And / or, the alkaline catalyst is selected from ammonia or organic amines; And / or, the surfactant is selected from at least one of Tween, alkylphenol polyoxyethylene ether, and block polyether.

4. The method for preparing core-shell structured functional microspheres according to claim 2 or 3, characterized in that, Includes the following steps: S1. Polysiloxane, alkoxysilane and ultraviolet absorber are dissolved in solvent I to form an oil phase; surfactant and solvent II are mixed to form an aqueous phase; S2. Add the oil phase to the aqueous phase, homogenize and emulsify to obtain an emulsified system; S3. Add an alkaline catalyst to the emulsion system and react to obtain the core-shell structured functional microspheres. Solvent I is selected from organic solvents with a boiling point below 100°C and that are immiscible with water; solvent II is selected from aqueous solutions of C1-C4 alkanols.

5. The method for preparing core-shell structured functional microspheres according to claim 4, characterized in that, In step S1, the mass ratio of the polysiloxane, alkoxysilane, ultraviolet absorber and solvent I is 1: (0.8-1.2): (1-1.5): (10-30); And / or, in step S1, the surfactant content in the aqueous phase is 0.5wt%-1.5wt%; And / or, in step S2, the volume ratio of the aqueous phase to the oil phase is (5-10):1; And / or, in step S3, the concentration of the alkaline catalyst is 20wt%-30wt%; the volume ratio of the alkaline catalyst to the emulsion system is 1:(10-20).

6. The application of the core-shell structured functional microspheres according to any one of claims 1-3 in the preparation of polymer composite materials.

7. A nylon material, characterized in that, Including the core-shell structured functional microspheres as described in any one of claims 1-3.

8. The nylon material according to claim 7, characterized in that, The nylon material comprises, by weight percentage, the following raw materials: 98.5%-99% nylon resin, 0.1%-1.0% core-shell structured functional microspheres, 0.1%-0.5% antioxidant, and 0.2%-0.8% lubricant.

9. The method for preparing the nylon material according to claim 7 or 8, characterized in that, Includes the following steps: The raw materials are mixed and melt-blended using a twin-screw extruder, then extruded and granulated to obtain the nylon material.

10. The use of the nylon material of claim 7 or 8 in the manufacture of automotive parts, photovoltaic modules, electronic and electrical housings or outdoor structural components.

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