High-dispersity polypropylene primary color master batch as well as preparation method and application thereof

Abstract

The invention provides a high-dispersity polypropylene primary color master batch as well as a preparation method and application thereof, and relates to the technical field of polypropylene, the high-dispersity polypropylene primary color master batch comprises the following components in parts by weight: 1-20 parts of pigment, 55-74 parts of polypropylene, 1-3 parts of nano titanium dioxide, 1-3 parts of nano silver, 1-3 parts of tungsten trioxide and 2-5 parts of dispersing agent. 1-3 parts of a phosphate heat stabilizer and 0.5-2 parts of an antioxidant. Through the composite synergistic effect of nano titanium dioxide and nano silver and other nano materials, the uniform dispersion performance of the polypropylene color master batch in a base material is improved, pigment agglomeration is effectively prevented, and the color consistency of a final product is ensured; functional components such as tungsten trioxide and nano zirconium oxide are introduced, so that the heat resistance and the ultraviolet aging resistance of the polypropylene product are enhanced, and the polypropylene keeps stable color under long-term outdoor use conditions and is not easy to fade and degrade.

Description

Technical Field

[0001] The present invention relates to the technical field of polypropylene, and in particular to a polypropylene-based masterbatch with high dispersibility, a preparation method thereof, and an application thereof. Background Art

[0002] Polypropylene is a thermoplastic resin belonging to the technical field of polyolefin-based polymer materials. It has the characteristics of low density, high strength, good rigidity, chemical corrosion resistance, excellent heat resistance and electrical insulation performance, and is widely used in many industrial fields such as packaging, textiles, household appliances, automotive parts and building materials.

[0003] In the prior art, there is a problem of insufficient dispersion of pigment particles in the actual processing of polypropylene materials. Due to the large particle size of pigment particles and the lack of an effective dispersion mechanism, pigment aggregation phenomena are likely to occur, resulting in uneven colors and large color deviations in polypropylene products, affecting the appearance quality of products. Therefore, improvements are needed. Summary of the Invention

[0004] The purpose of the present invention is to solve the drawbacks existing in the prior art, and to provide a polypropylene-based masterbatch with high dispersibility, a preparation method thereof, and an application thereof.

[0005] In order to achieve the above purpose, the present invention adopts the following technical scheme: A polypropylene-based masterbatch with high dispersibility, the polypropylene-based masterbatch with high dispersibility includes the following components by weight: 1-20 parts of pigment, 55-74 parts of polypropylene, 1-3 parts of nano-titanium dioxide, 1-3 parts of nano-silver, 1-3 parts of tungsten trioxide, 2-5 parts of dispersant, 1-3 parts of phosphoric acid ester heat stabilizer, 0.5-2 parts of antioxidant, 0.5-2 parts of light stabilizer, 1-3 parts of nano-zirconia, 0.5-2 parts of maleic anhydride grafted polypropylene.

[0006] Preferably, the dispersant is polyethylene wax, and the phosphoric acid ester heat stabilizer is triphenyl phosphate.

[0007] Preferably, the antioxidant is hydroxybenzoate, and the light stabilizer is carbon black.

[0008] The present invention provides a preparation method of a polypropylene-based masterbatch with high dispersibility, including the following steps: S1, raw material pretreatment, weigh polypropylene, nano-titanium dioxide, nano-silver, tungsten trioxide, nano-zirconia and maleic anhydride grafted polypropylene, place them in a vacuum drying oven to maintain the temperature at 40-60 °C and keep for 2-4 h; then screen the part with a particle size greater than 1 mm through a sieve and repeat the crushing until the overall particle size is below 1 mm to obtain pretreated raw materials; S2. High-speed mixing: Mix the pre-treated raw materials. Select a mixer with a rotation speed of 230 - 500 RPM and maintain the temperature in the range of 60 - 80°C. Add a dispersant, pigments, phosphate-based heat stabilizers, antioxidants, and light stabilizers during mixing. Through the shearing action of the rotating blades, the nano-pigment particles are combined with the polypropylene matrix. Blow in dry air during mixing and set the mixing duration to 10 - 20 minutes. Monitor whether the material distribution is uniform. After completion, cut off the mixing power supply and take samples for testing. Monitor the particle agglomeration situation through a microscope. If there is no obvious aggregation of particles, it is judged that the dispersion effect is ideal. Obtain the high-speed mixing product. S3. Supergravity field pre-treatment: Perform supergravity field pre-treatment on the high-speed mixing product. Select a supergravity machine with a rotation speed of 1000 - 1500 RPM and adjust the cylinder diameter in the range of 50 - 80 cm. The material remains in the centrifugal force field for 2 - 5 minutes. Enhance the dispersion stability of nano-titanium dioxide, nano-silver, and tungsten trioxide in the polypropylene medium through the acceleration difference between particles. Control the internal temperature in the range of 40 - 60°C. Obtain the supergravity field pre-treated product. S4. High-speed air jet impact dispersion: Perform air jet impact dispersion on the supergravity field pre-treated product. Use an air pressure of 1 - 3 bar and adjust the nozzle diameter in the range of 0.2 - 0.5 mm to enable the material to obtain de-agglomeration and dispersion under the impact of a high-speed jet. Control the jet angle at 30 - 60 degrees to form a multi-directional impact on the particles by changing the air flow direction. Obtain the high-speed air dispersion product. S5. Melt extrusion: Perform melt extrusion on the high-speed air dispersion product. Use a twin-screw extruder and set the screw diameter in the range of 30 - 40 mm. Divide the barrel temperature into three sections, which are 130 - 150°C, 160 - 180°C, and 180 - 200°C respectively, to gradually plasticize the polypropylene and fully mix it with the nano-pigments. Control the screw rotation speed at 100 - 200 RPM. Add a vacuum degassing section at the exhaust port to remove the volatile components generated during extrusion. Cool the product at the discharge port with a cooling water tank. After the extrudate flows out of the die head, use a pelletizing tool to cut it into strips. Obtain the melt extrudate. S6. Rotating electric field pre-treatment: Apply a high-frequency rotating electric field to the melt extrudate. The electric field frequency range is 10 - 30 kHz and an alternating potential is generated through a rotating electrode device. Induce the nano-pigment particles to be charged and arrange them in a circular path. Control the distance between the electrode and the melt at 5 - 10 cm. Apply the high frequency for 5 - 10 minutes to obtain the rotating electric field treated product. S7. Dynamic dispersion in a high-gravity field: subject the rotation electric field-treated material to dynamic dispersion in a high-gravity field. Use a high-speed rotating drum device and synchronously adjust the centrifugal acceleration to be between 500 - 800 g. The material forms a dynamic flow layer inside the rotating drum, causing the charged particles to produce radial and tangential dispersion effects. The residence time inside the drum is controlled within 3 - 5 min. After completion, a high-gravity field dynamic dispersion body is obtained. S8. Secondary high-speed air flow treatment: subject the high-gravity field dynamic dispersion body to secondary high-speed air flow treatment. The air flow pressure range is 1.5 - 3 bar, and a nozzle with a smaller diameter of 0.1 - 0.3 mm is selected to strengthen the agglomerate-breaking effect. The material undergoes repeated collisions and shearing in the accelerating jet. The spraying process lasts for 5 - 15 min. A secondary high-speed air flow-treated material is obtained. S9. Electrostatic self-assembly dispersion: continue to apply an electrostatic force inside the secondary high-speed air flow-treated material. The voltage range is 10 - 20 kV, and an auxiliary conductive plate is combined to guide the charged pigment particles to be arranged in a pre-set direction. After the particles are charged on the surface, electrostatic repulsive forces are generated between them, inhibiting the formation of agglomerates. Control the grounding potential of the target plate within the range of 0 - 5 V. Keep applying for 5 - 10 min and then stop the operation of the high-voltage power supply. An electrostatic self-assembly dispersion is obtained. S10. Cooling and solidification: subject the electrostatic self-assembly dispersion to cooling and solidification treatment. The conveyor belt speed is set at 1 - 2 m / min. The material is cooled down successively through the air-cooling zone and the water-cooling zone, causing the polypropylene matrix to gradually harden. A cooled and solidified product is obtained. S11. Pelletizing and cooling: perform pelletizing on the cooled and solidified product. The blade rotation speed of the pelletizer is controlled at 50 - 100 RPM, and the plate-shaped material is cut into particles with a size of 2 - 4 mm. After pelletizing, the temperature of the particles is further reduced to the range of 20 - 25 °C through room-temperature air flow. The dryer performs secondary dehumidification on the particles. The target masterbatch is obtained.

[0009] Preferably, in step S1, the sieve is a 100-mesh sieve.

[0010] Preferably, in step S10, the temperature of the air-cooling zone is 20 - 30 °C, and the temperature of the water-cooling zone is 5 - 15 °C.

[0011] Preferably, in step S11, the maintenance time of the secondary dehumidification is 2 - 4 h.

[0012] The present invention provides an application of a high-dispersibility polypropylene-based masterbatch, specifically its application in cable outer sheath materials.

[0013] 1. Compared with the prior art, through the combined synergistic effect of nanomaterials such as nano-titanium dioxide and nano-silver, the present invention enhances the uniform dispersion performance of polypropylene masterbatch in the substrate, effectively prevents pigment agglomeration, and ensures the color consistency of the final product. By introducing functional components such as tungsten trioxide and nano-zirconia oxide, the heat resistance and anti-ultraviolet aging performance of polypropylene products are strengthened, enabling polypropylene to maintain color stability under long-term outdoor use conditions and not easily fade or degrade. The maleic anhydride grafted polypropylene and the dispersant cooperate with each other to enhance the compatibility between the pigment and the matrix, improve the interfacial bonding effect between the masterbatch and the substrate, and further enhance the mechanical strength and processing stability of polypropylene products. In addition, the combined action of functional additives such as antioxidants and phosphate heat stabilizers effectively inhibits oxidation and thermal degradation behaviors during the processing, ensuring the processing fluidity of polypropylene materials and the long-term performance stability of the final products, meeting the production requirements of high-quality plastic products under complex process conditions.

[0014] 2. Compared with the prior art, the present invention realizes the efficient and uniform dispersion of nanoparticles inside the polypropylene matrix through the combined synergistic effect of pre-precise drying treatment of polypropylene raw materials and nano-pigments, multi-stage high-speed mechanical shearing, supergravity field induction, and high-speed air flow impact. At the same time, assisted by rotating electric field and electrostatic induction technologies, the pigment particles are precisely arranged and distributed along a specific path in the molten state. Finally, through melt extrusion and precise cooling and solidification, the ideal bonding state between the nano-pigment and the polypropylene substrate is ensured. Thus, the agglomeration problem of nano-pigments in polypropylene is improved, the particle dispersibility and spatial stability are enhanced, the uniformity and interfacial bonding force of nano-materials in the polymer matrix are ensured to be improved, the weather resistance, anti-aging performance, and photo-thermal stability of the materials are effectively enhanced, the appearance quality and long-term use reliability of polypropylene-based masterbatch products are improved, and the application stability and product added value in fields such as textiles, automotive parts, and household appliance casings are enhanced.

[0015] The technical solutions of the present invention will be further described in detail below through the accompanying drawings and embodiments. Description of the Drawings

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0017] Figure 1 It is a process flow diagram for the preparation method of a highly dispersible polypropylene-based masterbatch proposed by the present invention. Detailed Embodiments

[0018] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0019] Embodiment 1. A polypropylene-based masterbatch with high dispersibility. The polypropylene-based masterbatch with high dispersibility comprises the following components by weight: 10 parts of pigment, 70 parts of polypropylene, 3 parts of nano-titanium dioxide, 1 part of nano-silver, 3 parts of tungsten trioxide, 2 parts of dispersant, 3 parts of phosphate ester heat stabilizer, 0.5 part of antioxidant, 2 parts of light stabilizer, 1 part of nano-zirconia, and 2 parts of maleic anhydride grafted polypropylene.

[0020] In this embodiment, the dispersant is polyethylene wax, and the phosphate ester heat stabilizer is triphenyl phosphate.

[0021] In this embodiment, the antioxidant is hydroxybenzoate, and the light stabilizer is carbon black.

[0022] This embodiment provides a preparation method for the polypropylene-based masterbatch with high dispersibility, which includes the following steps: S1. Pretreatment of raw materials. Weigh polypropylene, nano-titanium dioxide, nano-silver, tungsten trioxide, nano-zirconia, and maleic anhydride grafted polypropylene, place them in a vacuum drying oven, maintain the temperature at -60°C for 4 hours, then screen the part with particle size greater than 1 mm through a sieve and repeat the pulverization until the overall particle size is below 1 mm to obtain the pretreated raw materials. S2. High-speed mixing. Mix the pretreated raw materials, select a mixer with a rotation speed of 500 RPM, and maintain the temperature in the range of 80°C. When stirring, add the dispersant, pigment, phosphate ester heat stabilizer, antioxidant, and light stabilizer, and make the nano-pigment particles combine with the polypropylene main body through the shearing action of the rotating blades. When stirring, introduce dry air, and set the stirring duration to 20 minutes, and monitor whether the material distribution is uniform. After completion, cut off the stirring power supply and take samples for testing, and monitor the particle agglomeration situation through a microscope. If there is no obvious aggregation phenomenon of the particles, it is judged that the dispersion effect is ideal. Obtain the high-speed mixing product. S3. Supergravity field pretreatment. Perform supergravity field pretreatment on the high-speed mixing product, select a supergravity machine with a rotation speed of 1500 RPM and adjust the cylinder diameter in the range of 80 cm. The material is kept in the centrifugal force field for 5 minutes to enhance the dispersion stability of nano-titanium dioxide, nano-silver, and tungsten trioxide in the polypropylene medium through the acceleration difference between particles. The internal temperature is controlled in the range of 60°C. Obtain the supergravity field pretreated material. S4. High-speed air flow impact dispersion: The hypergravity field pretreated material is subjected to air flow impact dispersion. The air flow pressure is 2 bar and the nozzle diameter is adjusted within the range of 0.5 mm, so that the material is broken up and dispersed under the impact of high-speed jet. The spraying angle is controlled at 45 degrees, and multi-directional impact on the particles is formed by changing the air flow direction; The high-speed air flow dispersed product is obtained; S5. Melt extrusion: The high-speed air flow dispersed product is subjected to melt extrusion. A twin-screw extruder is used and the screw diameter is set within the range of 40 mm. The barrel temperature is divided into three sections, which are 150 °C, 180 °C and 200 °C respectively, so that the polypropylene is gradually plasticized and fully mixed with the nano-pigment; The screw speed is controlled at 200 RPM; A vacuum degassing section is added to the exhaust port to remove the volatile components generated during the extrusion process; The discharge port is cooled in cooperation with a cooling water tank, and the extruded material is cut into strips by a pelletizing tool after flowing out of the die head; The melt extruded material is obtained; S6. Rotating electric field pretreatment: A high-frequency rotating electric field is applied to the melt extruded material. The electric field frequency range is 30 kHz and an alternating potential is generated by a rotating electrode device; Induce the nano-pigment particles to be charged and arranged in a circular path; The distance between the electrode and the melt is controlled at 10 cm; The high-frequency application duration is 10 min, and the rotating electric field treated material is obtained; S7. Hypergravity field dynamic dispersion: The rotating electric field treated material is subjected to hypergravity field dynamic dispersion. A high-speed rotating drum device is used and the centrifugal acceleration is synchronously adjusted between 800 g; The material forms a dynamic flow layer in the rotating drum, causing the charged particles to produce radial and tangential dispersion effects; The residence time in the drum is controlled at 5 min, and the hypergravity field dynamic dispersion body is obtained after completion; S8. Secondary high-speed air flow treatment: The hypergravity field dynamic dispersion body is subjected to secondary high-speed air flow treatment. The air flow pressure range is 3 bar and a nozzle with a smaller diameter of 0.3 mm is selected to strengthen the breaking-up effect; The material collides and shears again in the accelerating jet; The spraying process lasts for 10 min; The secondary high-speed air flow treated material is obtained; S9. Electrostatic self-assembly dispersion: Continue to apply an electrostatic force to the secondary high-speed air flow treated material. The voltage range is 15 kV and an auxiliary conductive plate is combined to guide the charged pigment particles to be arranged in a pre-set direction; After the particles are charged on the surface, electrostatic repulsive forces are generated between them, inhibiting the formation of agglomeration; The grounding potential of the target plate is controlled within the range of 3 V; After maintaining the application for 8 min, the operation of the high-voltage power supply is stopped; The electrostatic self-assembly dispersed material is obtained; S10. Cooling and solidification: The electrostatic self-assembly dispersed material is subjected to cooling and solidification treatment. The conveyor belt speed is set at 1 m / min, and the material is cooled successively through the air-cooling zone and the water-cooling zone, so that the polypropylene matrix is gradually hardened; The cooled and solidified product is obtained; S11, Granulation and cooling: Pelletize the cooled and solidified product. Control the blade rotation speed of the pelletizer at 80 RPM and cut the plate-like material into 4-mm pellets. After pelletizing, further reduce the temperature of the pellets to the range of 25°C through room-temperature air flow. The dryer performs secondary dehumidification on the pellets to obtain the target masterbatch.

[0023] In this embodiment, in step S1, the sieve is a 100-mesh sieve.

[0024] In this embodiment, in step S10, the temperature of the air-cooling zone is 30°C, and the temperature of the water-cooling zone is 15°C.

[0025] In this embodiment, in step S11, the maintenance time for secondary dehumidification is 4 h.

[0026] Example 2, different from Example 1: A highly dispersible polypropylene-based masterbatch, the highly dispersible polypropylene-based masterbatch comprises the following components by weight parts: 10 parts of pigment, 65 parts of polypropylene, 2 parts of nano-titanium dioxide, 1 part of nano-silver, 3 parts of tungsten trioxide, 5 parts of dispersant, 3 parts of phosphate ester heat stabilizer, 2 parts of antioxidant, 2 parts of light stabilizer, 2 parts of nano-zirconia, 2 parts of maleic anhydride grafted polypropylene.

[0027] Experimental method: Dispersion Test Method: This experiment aims to evaluate the degree of uniform dispersion of pigments and functional additives in the matrix of polypropylene-based masterbatches. First, prepare several masterbatch samples made from the same batch, each sample being about 5 grams. After uniform mixing, conduct the test. Place the samples in a constant-temperature drying oven and dry them at 60°C for 2 hours to ensure that the moisture content on the surface and inside of the samples is at a consistent level. Subsequently, use a high-speed mixing sample preparation device to pre-mix the masterbatch and colorless transparent polypropylene resin at a mass ratio of 1:10, and conduct melt extrusion sample preparation in an extruder within the temperature range of 180°C to 220°C to obtain a transparent sheet with a thickness of about 100 microns. Then, use an optical microscope to observe the cross-section and surface of the sheet. The magnification can be selected as 100 times or 200 times. Mainly observe whether there are obvious agglomerations, white spots or areas of particle accumulation in the pigment dispersion. To quantify the dispersion degree, statistical analysis of the number, size and distribution uniformity of pigment particles in the same field of view can be carried out in combination with image analysis software. The dispersion degree is usually expressed as a percentage, defined as the ratio of the particle area ratio in the ideal dispersion state to the particle area ratio in the actual dispersion state multiplied by 100%. At the same time, low-frequency ultrasonic assistance detection can be used. Add a small amount of the prepared sheet fragments to a certain amount of solution dissolved with an adhesive, and observe the dispersion stability time and the tendency of particle re-aggregation after the pigment is slowly leached out. The entire experiment requires comparing the microscopic observation images at different time points to judge whether re-agglomeration occurs between particles under external force disturbance or static conditions. Through this method, the dispersion degree of the sample can be evaluated and compared with the data of the control group. The higher the value, the better the dispersion performance.

[0028] Color intensity test method: Color intensity is used to evaluate the coloring ability of masterbatch in resin. In this experiment, a standard color difference meter or spectrophotometer is selected for testing. The specific operation is as follows: Prepare several masterbatch samples, mix them with general-purpose polypropylene according to the established addition ratio, and then make standard specimen sheets with a certain thickness (about 2 mm) in an injection molding or extrusion device. After the specimen sheets are cooled, use a calibrated spectrophotometer to measure at least three different positions under the D65 light source condition and record the Lab* values. To obtain the color intensity, it is necessary to compare the test specimen sheet with a reference white board and known standard samples: First, measure the reflectance or tristimulus values of the white board under the same instrument settings, and compare the measured values of this specimen with the white board values to obtain the relative color difference ΔE. At the same time, to further quantify the color intensity, this specimen can be compared with a series of standard samples with known coloring concentration gradients, and the coloring power of the current sample can be calculated through a colorimetric curve or relative absorbance. On this basis, the percentage representation of color intensity can be given. Usually, the intensity of the comparative example or the industry-recognized standard sample is taken as 100%, and then the relative color intensity of the masterbatch is converted according to the measured values. During the whole experimental process, the measurement environment (such as temperature, humidity, light source stability) needs to be strictly controlled, and the same spectrophotometer and the same set of calibration procedures are used to ensure the repeatability and comparability of the results. If the color intensity is significantly improved, it indicates that the dispersion state of the pigment in the polypropylene matrix is better, and the coloring effect exerted by the pigment per unit mass is higher.

[0029] Tensile Strength Test Method: The purpose of the tensile strength test is to evaluate the influence of the masterbatch added to the polypropylene matrix on the mechanical properties of the final product. For the specific method, refer to standards such as GB / T 1040.2 - 2006 or ISO 527-1. First, by means of injection molding or extrusion molding, the masterbatch and pure polypropylene are fully mixed in a given ratio to prepare standard dumbbell-shaped or strip-shaped specimens with a thickness generally of 1 - 3 mm, and the length and shape meet the requirements of the corresponding test standards. The specimens are conditioned in an environment of 23 ± 2°C and a relative humidity of 50 ± 5% for 24 hours to make the internal stress and environmental state tend to be stable. Subsequently, an electronic tensile testing machine (equipped with suitable fixtures and range sensors) is used to stretch the specimens at a constant stretching speed (such as 50 mm / min or other standard settings) until they break. The stress-strain curve during the stretching process is recorded in real time, and the tensile strength is determined by the peak stress. At the same time, parameters such as the tensile modulus and elongation at break can be calculated from the curve. To ensure the statistical significance of the test results, usually at least 5 parallel specimens are tested for each formulation, and data with obvious defects or improper operations during the test are excluded. Finally, the calculated average value is the tensile strength of this formulation. If the masterbatch is well dispersed and has good interfacial compatibility with the matrix, it will, to a certain extent, improve or maintain a high level of tensile strength; if the dispersion is poor, there may be stress concentration points, resulting in a decrease in the mechanical properties of the material. This method can quantitatively illustrate the influence of the present invention on the mechanical properties of the product.

[0030] Impact Strength Test Method: The impact strength test mainly measures the ability of the material to resist damage when subjected to external impact. This experiment can be carried out by the cantilever beam or simply supported beam impact test with reference to standards such as GB / T 1043.1 - 2008 or ISO 179. Before the test, the masterbatch and polypropylene resin are mixed according to the designed formulation and extruded or injection molded into specimens with dimensions meeting the requirements of the impact test, such as rectangular bars of 80 mm × 10 mm × 4 mm. If the simply supported beam impact method is used, a standard U-shaped or V-shaped notch needs to be cut in the middle of the specimen, and the notch size and radius meet the test standards. After the specimens are placed in an environment of 25°C and a relative humidity of 50% for 24 hours, they are placed on the impact testing machine, and impact is applied to the notch part, and the fracture energy or fracture type (complete fracture, partial fracture, no fracture) and the corresponding impact strength value are recorded. During the test, it is necessary to ensure that the impact energy of the pendulum matches the thickness of the specimen to avoid oversaturation or insufficient energy to break the specimen. Repeat the test on at least 5 samples, and take the average value as the final result. A high impact strength usually means good interfacial bonding inside the material, no excessive agglomeration of pigments or other fillers, and they can be evenly dispersed and form good synergy with polypropylene, reducing stress concentration. If the dispersion and compatibility are insufficient, microcrack sources will appear, making the material more prone to brittle fracture under impact. The impact strength data obtained by this method can intuitively reflect the influence of the masterbatch of the present invention on the overall toughness of the material.

[0031] Thermal stability test method: The thermal stability test aims to evaluate the ability of masterbatch to maintain its structure and properties in high-temperature processing or usage environments, and the general test specifications of thermogravimetric analysis (TGA) or differential scanning calorimetry (DSC) can be referred to. Taking TGA as an example: First, blend the masterbatch with pure polypropylene substrate, and form small samples with a mass of about 510 mg through twin-screw extrusion or injection molding. Using a thermogravimetric analyzer, under an inert atmosphere (such as nitrogen), heat from room temperature to 600 °C at a heating rate of 10 °C / min. Record the curve of sample mass change with temperature, focusing on the temperature at 5% and 10% mass loss, and the temperature peak at the maximum decomposition rate. For evaluating the heat resistance of masterbatch within the conventional processing temperature range (150 - 220 °C), it can also be observed that the sample basically maintains mass stability within this range, without generating a large amount of volatile substances or decomposition products. If the masterbatch is well-dispersed and the nanoparticles or additives used in the formulation have a barrier or endothermic effect, the temperature point of material decomposition or degradation can be postponed to a certain extent, thereby improving the overall thermal stability. In addition to TGA, methods such as DSC or heat distortion temperature (HDT) test can also be used to further prove the reliability of use in a long-term high-temperature environment. By comparing the thermal stability temperature and decomposition behavior of the comparative example and the examples of the present invention, the advantages of the present invention can be quantitatively evaluated.

[0032] Melt Flow Index (MFI) test method: Melt Flow Index (MFI) is a commonly used index to reflect the flow characteristics of thermoplastics in the molten state. When measuring, refer to standards such as GB / T 3682 - 2018 or ASTM D1238. After mixing the prepared masterbatch with polypropylene to form relatively uniform granules or powders, place them at the feeding port of the melt flow index tester. Select appropriate temperature (such as 190 °C or 230 °C) and load (usually 2.16 kg or 5.0 kg) according to the material grade and estimated flow characteristics, and preheat for 5 minutes to ensure that the material is fully melted and the temperature is uniform. Then open the discharge port, and use a manual or automatic switching device to record the mass or length of the molten material extruded within a specified time, and convert it into g / 10min according to the standard. The MFI value reflects the processing flow performance of the material: a large value indicates a relatively low melt viscosity and easy flow; a small value indicates a relatively high melt viscosity. For a system containing nano-pigments or fillers, if it is well-dispersed and the compatibility between the additive and the matrix is good, it usually will not overly increase the melt viscosity, while if agglomeration occurs, it will cause flow blockage and a significant decrease in the MFI value. In addition, if the sample decomposes or generates a large amount of gas at high temperature, it will also affect the measurement results. To ensure the accuracy of the results, usually repeat the test 3 - 5 times for each formulation and take the average value. Through this method, the influence of the masterbatch formulation on the processing flow performance of polypropylene can be confirmed and directly compared with the comparative example.

[0033] The finished materials prepared in Examples 1-2 were tested. Comparative Example 1 was the polypropylene material disclosed in Patent Publication No. CN116063788A. The experimental results are as follows: Table 1 Performance test data Performance Index Comparative Example 1 Example 1 Example 2 Dispersion Degree (%) 85 94 96 Color Strength (%) 90 98 99 Tensile Strength (MPa) 22 26 27 Impact Strength (kJ / m²) 4.0 4.8 5.1 Thermal Stability (℃) 210 230 235 Melt Flow Index (g / 10min) 10 9 8 As can be seen from Table 1, Examples 1-2 have better dispersion stability and color rendering effects compared to Comparative Example 1. At the same time, they have higher mechanical properties and thermal stability, and also show good balance in processing fluidity. Since the pigments and additives are more finely and evenly dispersed in the matrix, defects caused by agglomeration are avoided, so the impact resistance and appearance quality of the products are also significantly better than those of the comparative example, showing good industrial application potential.

Claims

1. A highly dispersed polypropylene-based masterbatch, characterized in that: The highly dispersible polypropylene-based masterbatch comprises the following components in parts by weight: 1-20 parts of pigment, 55-74 parts of polypropylene, 1-3 parts of nano titanium dioxide, 1-3 parts of nano silver, 1-3 parts of tungsten trioxide, 2-5 parts of dispersant, 1-3 parts of phosphate heat stabilizer, 0.5-2 parts of antioxidant, 0.5-2 parts of light stabilizer, 1-3 parts of nano zirconium oxide, and 0.5-2 parts of maleic anhydride grafted polypropylene.

2. The highly dispersed polypropylene-based masterbatch according to claim 1, characterized in that: The dispersant is polyethylene wax, and the phosphate ester heat stabilizer is triphenyl phosphate.

3. The highly dispersed polypropylene-based masterbatch according to claim 1, characterized in that: The antioxidant is hydroxybenzoic acid ester, and the light stabilizer is carbon black.

4. The method for preparing highly dispersible polypropylene-based masterbatch according to claim 1, characterized in that: The following steps are involved: S1, raw material pretreatment, weighing polypropylene, nano titanium dioxide, nano silver, tungsten trioxide, nano zirconium oxide and maleic anhydride grafted polypropylene, placing them in a vacuum drying oven at a temperature of 40-60°C for 2-4 hours; then screening the particles larger than 1 mm through a sieve and repeatedly crushing them until the overall particles are less than 1 mm, to obtain the pretreated raw material; S2, high-speed mixing, mixing the pretreated raw materials, using a mixer with a rotation speed of 230-500RPM, and maintaining the temperature in the range of 60-80°C; adding dispersants, pigments, phosphate heat stabilizers, antioxidants and light stabilizers during stirring, and combining the nano-pigment particles with the polypropylene body through the shearing action of the rotating blades; blowing dry air into the stirring, and setting the stirring time to 10-20min, monitoring whether the material distribution is uniform; after completion, cutting off the stirring power supply and taking samples for detection, monitoring the agglomeration of particles through a microscope, if there is no obvious aggregation of particles, it is judged that the dispersion effect is ideal; obtaining a high-speed mixed product; S3, high-gravity field pretreatment, the high-speed mixed product is subjected to high-gravity field pretreatment, a high-gravity machine with a rotation speed of 1000-1500RPM is selected and the cylinder diameter is adjusted to the range of 50-80cm, the material is kept in the centrifugal field for 2-5min, and the dispersion stability of nano-titanium dioxide, nano-silver and tungsten trioxide in the polypropylene medium is enhanced by the acceleration difference between particles; the internal temperature is controlled in the range of 40-60°C; and a high-gravity field pretreated product is obtained; S4, high-speed airflow impact dispersion, the supergravity field pre-treated material is subjected to airflow impact dispersion, the airflow pressure is 1-3 bar and the nozzle diameter is adjusted in the range of 0.2-0.5 mm, so that the material is broken and dispersed under the impact of high-speed jets; the injection angle is controlled at 30-60 degrees, and a multi-directional impact effect on the particles is formed by changing the airflow direction; a high-speed airflow dispersion product is obtained; S5, melt extrusion, melt extrusion of the high-speed airflow dispersion product, using a twin-screw extruder and setting the screw diameter in the range of 30-40 mm, the barrel temperature is divided into three sections, namely 130-150° C., 160-180° C. and 180-200° C., so that the polypropylene is gradually plasticized and fully mixed with the nano-pigment; the screw speed is controlled at 100-200 RPM; a vacuum degassing section is added to the exhaust port to remove the volatile components generated during the extrusion process; the discharge port is equipped with a cooling water tank for cooling, and the extrudate is cut into strips by a pelletizing tool after flowing out of the die head; obtaining a molten extrudate; S6, rotating electric field pretreatment, applying a high-frequency rotating electric field on the molten extrudate, the electric field frequency range is 10-30kHz, and an alternating potential is generated through a rotating electrode device; inducing the nano-pigment particles to be charged and arranged in a circular path; the distance between the electrode and the melt is controlled to be 5-10cm; the high frequency is applied for 5-10min, and a rotating electric field treated product is obtained; S7, high gravity field dynamic dispersion, the rotating electric field treated material is subjected to high gravity field dynamic dispersion, a high-speed rotating drum device is used and the centrifugal acceleration is synchronously adjusted between 500-800g; the material forms a dynamic fluidized layer in the rotating drum, so that the charged particles produce radial and tangential dispersion effects; the residence time in the drum is controlled to be 3-5min, and after completion, a high gravity field dynamic dispersion is obtained; S8, secondary high-speed airflow treatment, the high-gravity field dynamic dispersion is subjected to secondary high-speed airflow treatment, the airflow pressure range is 1.5-3 bar and a nozzle with a smaller diameter of 0.1-0.3 mm is selected to strengthen the deagglomeration effect; the material is collided and sheared again in the accelerated jet; the injection process lasts for 5-15 minutes; and the secondary high-speed airflow treated material is obtained; S9, electrostatic self-assembly dispersion, continue to apply electrostatic force in the secondary high-speed airflow treatment material, the voltage range is 10-20kV and combined with an auxiliary conductive plate, guide the charged pigment particles to a preset direction; after the particle surface is charged, electrostatic repulsion is generated between each other to inhibit agglomeration formation; control the target plate ground potential in the range of 0-5V; keep applying for 5-10 minutes and then stop the high voltage power supply; Obtaining an electrostatic self-assembled dispersion; S10, cooling and curing, cooling and curing the electrostatic self-assembled dispersion, the conveyor belt speed is set at 1-2m / min, the material is cooled in turn through the air cooling zone and the water cooling zone, so that the polypropylene matrix is ​​gradually hardened; and a cooled and cured product is obtained; S11, granulation and cooling, pelletizing the cooled solidified product, the blade speed of the pelletizer is controlled at 50-100RPM and the plate-like material is cut into 2-4mm particles; after pelletizing, the temperature of the particles is further reduced to the range of 20-25°C by room temperature wind flow; the dryer performs secondary dehumidification on the particles; and the target masterbatch is obtained.

5. The method for preparing a highly dispersible polypropylene-based masterbatch according to claim 4, characterized in that: In step S1, the sieve is a 100-mesh sieve.

6. The method for preparing a highly dispersible polypropylene-based masterbatch according to claim 4, characterized in that: In step S10, the temperature of the air cooling zone is 20-30°C, and the temperature of the water cooling zone is 5-15°C.

7. The method for preparing a highly dispersible polypropylene-based masterbatch according to claim 4, characterized in that: In step S11, the secondary dehumidification is maintained for 2-4 hours.

8. An application of a highly dispersed polypropylene-based masterbatch, characterized in that: Its application in cable sheath materials.

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