Composite rare earth element lossless industrial flaw detection polypropylene master batch and preparation method thereof

Abstract

The invention belongs to the field of polypropylene materials, and relates to a composite rare earth element lossless industrial flaw detection polypropylene master batch and a preparation method thereof. According to the invention, through core-shell structure modification and surface grafting, the compatibility of lanthanide fluorescent nanoparticles and a polypropylene body is increased, so that the nanoparticles can be uniformly dispersed in a polypropylene matrix, and the overall performance of the composite material is improved. The characteristic that the composite rare earth element nanoparticles have an X-ray imaging effect is utilized, the composite rare earth element nanoparticles are compounded with the polypropylene material, industrial nondestructive inspection after the modified polypropylene material is processed into the automobile parts is achieved, and the problem that application of a conventional X-ray inspection means in the field of industrial inspection of the PP modified automobile parts is limited is solved.

Description

Technical Field

[0001] The invention belongs to the field of polypropylene materials and relates to a polypropylene masterbatch for composite rare earth element non-destructive industrial flaw detection and a preparation method thereof. Background Art

[0002] Polypropylene (PP) is a thermoplastic widely used in automotive parts, household appliances, and other fields, exhibiting excellent mechanical properties, heat resistance, and processing capabilities. With the development of industrial technology, the application of PP in automotive parts is becoming increasingly widespread, and the requirements for its quality and safety are becoming increasingly stringent. During industrial production, PP may contain internal defects such as bubbles, cracks, and impurities, which can seriously affect the performance and safety of the product. Therefore, nondestructive testing of PP is of great significance.

[0003] At present, the commonly used polypropylene modification methods in industry mainly include adding toughening agents, fillers and various functional additives. For example, CN106633412A discloses a high elongation at break polypropylene composition, which comprises 25-99.4 parts of polypropylene, 0-20 parts of toughening agent, 0-40 parts of mineral filler and other components. By adding nano-nucleating masterbatch, a polypropylene composition with high elongation at break, high toughness, high heat resistance and high modulus can be obtained under different types and proportions of polypropylene, filler, toughening agent and additives. CN103059417A discloses a filled polypropylene composite material for rapid prototyping parts, which comprises 60-88 parts of polypropylene, 1-25 parts of toughening agent, 10-30 parts of mineral powder filler, 1-5 parts of nano-filler masterbatch, etc. by weight, and has the characteristics of good material fluidity, low shrinkage and good dimensional stability.

[0004] In terms of functional polypropylene materials, CN108299729A discloses a polypropylene functional composite material with a fluorescent effect. The polypropylene composite material is mainly composed of 5-10 parts of a fluorescent polypropylene functional masterbatch, 45-95 parts of conventional polypropylene, 0-40 parts of an inorganic filler, and 0-20 parts of an elastomer. This can effectively reduce the amount of fluorescent functional additives while ensuring the material has a good fluorescent effect. CN111410790B discloses a humidity-sensitive fluorescent modified polypropylene material, which includes 50-95 parts of a polypropylene resin, 5-50 parts of a toughening agent, 0.1-5 parts of a moisture-capturing functional masterbatch, and 0.1-5 parts of a fluorescent masterbatch. This material not only has high fluorescence intensity, is non-toxic and harmless, and is non-radioactive, but also has a strong linear relationship between its fluorescence intensity and humidity, making it suitable for moisture detection. CN112457592A discloses a long-lasting anti-fouling, anti-sticking and light-resistant automotive polypropylene composite material, specifically composed of 29-97wt% polypropylene, 1-30wt% mineral filler, 1-30wt% fluorine-containing masterbatch, 0.01-5wt% rare earth cerium nanomaterial, etc., and can be produced by industrial methods with good surface long-lasting anti-fouling, anti-sticking and light-resistant automotive polypropylene composite material

[0005] However, existing polypropylene materials still have significant shortcomings in the field of industrial flaw detection. When applied to PP-modified automotive parts, traditional X-ray flaw detection technology suffers from low contrast and insufficient resolution in the flaw detection images due to the low density and small X-ray absorption coefficient of PP materials, making it difficult to effectively detect tiny defects within the material. In particular, when the defects are small or located in complex structural parts, conventional X-ray flaw detection methods have a low signal-to-noise ratio, making it impossible to accurately identify and locate the defects. Furthermore, existing fluorescent polypropylene materials primarily focus on their fluorescence effects under visible light or specific functional applications, lacking specialized designs for industrial non-destructive testing and failing to meet the demands of high-precision, high-efficiency industrial flaw detection.

[0006] Currently, no patents, domestic or international, address the specific needs of industrial flaw detection for PP-modified automotive parts. Specifically, there is a lack of technical solutions that combine the fluorescence properties of rare earth elements with polypropylene to enhance industrial flaw detection. Therefore, developing a polypropylene masterbatch that can improve the flaw detection performance of PP-modified automotive parts is of great practical significance for enhancing the quality inspection and safety of automotive parts. Summary of the Invention

[0007] The purpose of the present invention is to address the above-mentioned problems existing in the prior art and propose a polypropylene masterbatch with composite rare earth elements for non-destructive industrial flaw detection, thereby solving the technical problem that conventional X-ray flaw detection methods are limited in the field of industrial flaw detection of PP modified automotive parts, and achieving the technical effect of improving X-ray imaging and clearly identifying tiny defects inside the parts.

[0008] The purpose of the present invention can be achieved through the following technical solutions:

[0009] A polypropylene masterbatch for composite rare earth element non-destructive industrial flaw detection comprises the following raw materials in parts by mass: 60-75 parts of polypropylene, 10-20 parts of a toughening agent, 10-20 parts of a filler, 4-10 parts of lanthanide fluorescent nanoparticles, and 40-60 parts of an auxiliary agent.

[0010] Preferably, the lanthanide fluorescent nanoparticles are core-shell structures, wherein the core is composed of the matrix material NaLuF4, the sensitizing ion Yb 3 + , luminescence center Tm 3+ It is composed of the matrix material NaLuF4, the sensitizing ion Yb 3+ , luminescence center Tm 3+ The core is composed of a silicon dioxide coating and grafted with polydimethylsiloxane. This structural design not only enhances the stability of the nanoparticles, but also improves their dispersibility in the polypropylene matrix.

[0011] Furthermore, the preparation method of the lanthanide fluorescent nanoparticles comprises the following steps:

[0012] S1. adding lutetium chloride, ytterbium chloride and thulium chloride to oleic acid and octadecene for heating reaction;

[0013] S2, then adding sodium hydroxide and ammonium fluoride dissolved in an organic solvent, and performing gradient heating to obtain semi-finished nanoparticles;

[0014] S3, dissolving the semi-finished nanoparticles in an organic solvent, adding sodium hydroxide and ethyl silicate and heating to react to obtain silica-coated nanoparticles;

[0015] S4. The silica-coated nanoparticles are centrifuged and then grafted with polydimethylsiloxane to obtain lanthanide fluorescent nanoparticles.

[0016] Preferably, the mass ratio of lutetium chloride, ytterbium chloride and thulium chloride is (35-45):(8-12):1.

[0017] The present invention can adjust the composition and structure of lanthanide fluorescent nanoparticles by controlling the ratio of lutetium chloride, ytterbium chloride and thulium chloride, thereby optimizing the fluorescence performance. 3 + acts as a sensitizing ion, effectively transferring the absorbed X-ray energy to Tm 3+ , and Tm 3+ As a luminescent center, it can emit fluorescence of a specific wavelength. 3+ It can provide a stable matrix structure to make Yb 3 + and Tm 3+It can play a better role, thereby improving the fluorescence intensity and luminescence efficiency of nanoparticles and enhancing the X-ray imaging effect. The appropriate ratio can ensure the stability of the crystal structure of nanoparticles. Excessive or insufficient elements may cause crystal structure defects or instability, affecting their dispersibility and compatibility in the polypropylene matrix. Excessive Tm 3+ It may cause too many defects in the crystal, reducing its stability; while the appropriate amount of Yb 3 + and Lu 3+ It helps to form a complete crystal structure and improve the thermal and chemical stability of nanoparticles.

[0018] Different rare earth elements have different X-ray absorption capabilities and luminescence efficiencies. By controlling the ratio of the three, the present invention can optimize the X-ray absorption and luminescence characteristics of nanoparticles, enabling them to produce stronger and clearer fluorescence signals under X-ray excitation, thereby improving the resolution and sensitivity of non-destructive testing and better detecting tiny defects inside polypropylene materials.

[0019] Preferably, the heating temperature in step S1 is 150-180° C. and the heating time is 0.5-1.5 h;

[0020] Preferably, the gradient heating in step S2 is firstly heated at 100-125° C. until the methanol is completely volatilized, and then heated to 250-350° C. for reaction for 0.5-2.5 h.

[0021] Preferably, the organic solvent includes at least one of methanol, ethanol and n-hexane.

[0022] The gradient heating method of the present invention gradually increases the reaction temperature, allowing the reactants to fully react at different temperature stages. At a lower temperature, methanol is first volatilized to remove the solvent, preventing violent boiling and splashing of the solvent at high temperatures while allowing for initial contact and mixing of the reactants. As the temperature gradually increases, the chemical reaction between the reactants becomes more intense and complete, facilitating the production of structurally sound nanoparticles with stable performance. Gradient heating helps control the grain growth process of the nanoparticles. At lower temperatures, crystal nuclei begin to form, and as the temperature rises, the nuclei gradually grow. By controlling the heating rate and temperature range, the nanoparticles' grain size can be made uniform, avoiding the formation of oversized or undersized grains, thereby improving the nanoparticles' optical properties and stability. This uniform grain size helps improve the dispersibility of the nanoparticles in the polypropylene matrix and enhances their compatibility with the matrix. Gradient heating protects the reaction system from sudden, intense thermal shock at high temperatures, reducing the occurrence of side reactions. Direct high-temperature heating can cause reactant decomposition, oxidation, or other side reactions, resulting in impurities or defects that can affect the quality and performance of the nanoparticles. Gradient heating can make the reaction system gradually adapt to temperature changes, reduce the probability of side reactions, and improve the purity and quality of nanoparticles.

[0023] Preferably, the amount of sodium hydroxide added in step S2 is 30-35% of the total mass of lutetium chloride, ytterbium chloride and thulium chloride, and the amount of ammonium fluoride added is 50-55% of the total mass of lutetium chloride, ytterbium chloride and thulium chloride.

[0024] Preferably, the amount of sodium hydroxide in step S3 is 25-30% of the total mass of lutetium chloride, ytterbium chloride and thulium chloride, and the amount of ethyl silicate added is 55-60% of the total mass of lutetium chloride, ytterbium chloride and thulium chloride.

[0025] Preferably, the heating temperature in step S3 is 50-80℃, and the time is 0.5-1.5h.

[0026] Preferably, the grafting of polydimethylsiloxane comprises dispersing the silica-coated nanoparticles in an organic solvent, then adding polydimethylsiloxane to the solution and stirring to react, and finally centrifuging, washing and drying to obtain lanthanide fluorescent nanoparticles.

[0027] Preferably, the stirring reaction temperature is 50-80℃.

[0028] The present application enables the chemical reaction of PDMS with the hydroxyl groups on the surface of the silica, forming Si-O-Si bonds, and grafting PDMS onto the surface of the nanoparticles. The purpose of grafting PDMS is to further improve the compatibility of the nanoparticles with the polypropylene matrix, so that the nanoparticles can be better dispersed in the polypropylene, and the overall performance of the composite material is improved.

[0029] Preferably, the median particle size of the lanthanide fluorescent nanoparticles is 50-400nm.

[0030] Further preferably, the median particle size of the lanthanide fluorescent nanoparticles is 100-300nm.

[0031] By controlling the particle size of lanthanide fluorescent nanoparticles, the present invention enables a more even dispersion within the polypropylene matrix, creating a more refined internal structure. Under X-ray excitation, these evenly distributed nanoparticles produce a clearer, more detailed fluorescence signal, thereby improving the resolution of the flaw detection image and enabling inspectors to more accurately identify and locate minor defects within the material, such as microcracks and bubbles. In contrast, if the nanoparticles are too large or unevenly distributed, the flaw detection image will be blurred, reducing detection accuracy. Furthermore, nanoparticles of an appropriate particle size have a larger specific surface area, which can more effectively absorb X-ray energy and convert it into a fluorescence signal. A smaller particle size helps increase the interaction probability between the nanoparticles and X-rays, improving energy conversion efficiency, thereby making the fluorescence signal stronger and more stable. Furthermore, during the luminescence process, the uniformly small-sized nanoparticles allow for more efficient energy transfer between the rare earth ions within them, further improving luminescence efficiency and enhancing flaw detection effectiveness. Controlling the nanoparticle size within a certain range can better balance the overall performance of the polypropylene material, including mechanical properties, thermal stability, and processing properties. Smaller particle sizes help minimize the negative impact of nanoparticles on the mechanical properties of materials, such as reducing strength due to nanoparticle agglomeration. Furthermore, evenly dispersed, small-sized nanoparticles improve the thermal and dimensional stability of the material, enabling it to maintain excellent performance during processing and use. This helps ensure the reliability and durability of polypropylene masterbatch in applications such as automotive parts.

[0032] Preferably, the toughening agent includes at least one of ethylene-propylene copolymer, ethylene-propylene-diene copolymer, and polyolefin elastomer.

[0033] Preferably, the filler includes at least one of hollow glass microspheres, calcium carbonate, talc, and glass fiber. These fillers are selected to enhance the mechanical properties and thermal stability of the polypropylene masterbatch.

[0034] Preferably, the additives include at least one of a lubricant, a plasticizer, a flame retardant, an antistatic agent, and a stabilizer. The addition of these additives helps to improve the processing properties of the material and the performance of the final product.

[0035] The present invention also provides a method for preparing a polypropylene masterbatch for non-destructive industrial flaw detection of composite rare earth elements, which comprises the following steps: mixing polypropylene, a toughening agent, a filler, lanthanide fluorescent nanoparticles, and an additive, and then extruding and granulating the mixture in an extruder.

[0036] Preferably, the extrusion granulation temperature is 190-230° C. This temperature range ensures uniform mixing of materials and a stable processing process.

[0037] The beneficial effects of the present invention are:

[0038] 1. The application utilizes the characteristic of the composite rare earth element nanoparticles having X-ray imaging effect, and composites the nanoparticles with polypropylene material, so as to realize the industrial nondestructive detection of the modified polypropylene material after being processed into automobile parts, and solves the problem that the conventional X-ray detection means is limited in application in the field of industrial detection of the PP modified automobile parts.

[0039] 2. After X-ray detection and photographic imaging, the application can clearly distinguish the tiny defects (such as black holes) in the parts, significantly improves the resolution and signal-to-noise ratio, and makes up for the deficiency of the prior art.

[0040] 3. The application increases the compatibility of the lanthanide fluorescent nanoparticles and the polypropylene body through core-shell structure modification and surface grafting, so that the nanoparticles can be uniformly dispersed in the polypropylene matrix, and the overall performance of the composite material is improved.

[0041] 4. The route of the application for the nondestructive industrial detection of the polypropylene automobile parts is convenient and easy to obtain raw materials, and the preparation method is simple, and has good industrial application prospect.

[0042] 5. The application improves the photon conversion efficiency, realizes long-time detection, has no significant afterglow interference, achieves the purpose of cooperating with X-ray imaging to perform nondestructive industrial detection of the internal automobile parts, and fills the technical blank in the domestic field. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 The transmission electron microscope characterization diagram of the lanthanide fluorescent nanoparticles prepared in Example 1.

[0044] Figure 2 The scanning imaging picture of the X-ray detection of the polypropylene master batch prepared in Example 1. DETAILED DESCRIPTION

[0045] The following is a specific embodiment of the application, which further describes the technical solutions of the application, but the application is not limited to these embodiments.

[0046] The preparation method of the lanthanide fluorescent nanoparticles in the following examples includes the following steps:

[0047] S1, 224.8mg of lutetium chloride, 50.4mg of ytterbium chloride, and 5.5mg of thulium chloride are added to 8ml of oleic acid and 12ml of octadecene for heating reaction at 160℃ for 1h;

[0048] S2, then 80mg of sodium hydroxide and 148mg of ammonium fluoride dissolved in methanol are added, and gradient heating is performed, first heated at 120℃ until the methanol is completely volatilized, and then heated to 300℃ for 1h to obtain NaLuF4:Yb 3+ , Tm 3+ particles;

[0049] S3, 1ml of NaLuF4:Yb 3+ ,Tm 3+ After the particles were dissolved in n-hexane to obtain a clear and transparent solution, 30 mg of sodium hydroxide and 120 μL of ethyl silicate were added and heated at 70 °C for 1.5 h;

[0050] S4. After the reaction is complete, the solution is centrifuged and the nanoparticles are dispersed in 10 mL of n-hexane to form a uniform solution. Then, 50 mg of polydimethylsiloxane (PDMS) is added to the solution, and the reaction is carried out at 70°C with stirring. After the reaction is complete, the PDMS-grafted nanoparticles are separated from the solution by centrifugation, washed, and dried to obtain lanthanide fluorescent nanoparticles with a median particle size of 200 nm.

[0051] The toughening agent was ENGAGE 7467 toughening agent purchased from Dow Chemical;

[0052] The filler was brand TYT-777A filler purchased from Haicheng Tianyuan Chemical Co., Ltd.

[0053] Polypropylene was purchased from CNOOC Shell with the brand name EP548R.

[0054] The additives were model 3299 flake graphite purchased from Ningbo Dingxin Innovation Materials Co., Ltd. and hollow glass microspheres purchased from Zhengzhou Shenglait Hollow Glass Microsphere New Materials Co., Ltd.: hollow glass microsphere model HL46, density 0.45 g / cm 3 .

[0055] The preparation method of the polypropylene masterbatch of the present invention is further described in detail below through specific examples.

[0056] Example 1:

[0057] S1. Prepare the raw materials according to the following mass parts: 70 parts of polypropylene, 15 parts of toughening agent, 15 parts of filler, 8 parts of lanthanide fluorescent nanoparticles, 25 parts of flake graphite, and 25 parts of hollow glass microspheres.

[0058] S2. The above raw materials were mixed in proportion, mixed at 50 rpm for about 1 minute, and added into a single-screw extruder for melt extrusion, granulation, and drying. The temperature of the single-screw extruder was 180° C. from the feeding section to the die head.

[0059] Figure 1 This is a transmission electron microscopy image of the lanthanide fluorescent nanoparticles prepared in Example 1. It can be seen from the image that the nanoparticles have a core-shell structure and a particle size of about 200 nm.

[0060] Figure 2This is a scanning image of the polypropylene masterbatch prepared in Example 1. As can be seen from the figure, after X-ray detection and imaging, tiny defects inside the part (black cavities indicated by arrows) can be clearly distinguished, and the scale is 50 μm.

[0061] Example 2:

[0062] S1. Prepare the raw materials according to the following mass parts: 60 parts of polypropylene, 10 parts of toughening agent, 10 parts of filler, 4 parts of lanthanide fluorescent nanoparticles, 25 parts of flake graphite, and 25 parts of hollow glass microspheres.

[0063] S2. The above raw materials were mixed in proportion, mixed at 50 rpm for about 1 minute, and added into a single-screw extruder for melt extrusion, granulation, and drying. The temperature of the single-screw extruder was 180° C. from the feeding section to the die head.

[0064] Example 3:

[0065] S1. Prepare the raw materials according to the following mass parts: 75 parts of polypropylene, 20 parts of toughening agent, 20 parts of filler, 10 parts of lanthanide fluorescent nanoparticles, 25 parts of flake graphite, and 25 parts of hollow glass microspheres.

[0066] S2. The above raw materials were mixed in proportion, mixed at 50 rpm for about 1 minute, and added into a single-screw extruder for melt extrusion, granulation, and drying. The temperature of the single-screw extruder was 180° C. from the feeding section to the die head.

[0067] Example 4:

[0068] The only difference from Example 1 is that, in the preparation process of lanthanide fluorescent nanoparticles, step S1 is: 50.4 mg of ytterbium chloride and 5.5 mg of thulium chloride are added to 8 ml of oleic acid and 12 ml of octadecene and heated at 160° C. for 1 hour.

[0069] Example 5:

[0070] The only difference from Example 1 is that, in the preparation process of lanthanide fluorescent nanoparticles, step S1 is: 224.8 mg of lutetium chloride and 5.5 mg of thulium chloride are added to 8 ml of oleic acid and 12 ml of octadecene and heated at 160° C. for 1 h.

[0071] Example 6:

[0072] The only difference from Example 1 is that, in the preparation process of lanthanide fluorescent nanoparticles, step S1 is: 224.8 mg of lutetium chloride and 50.4 mg of ytterbium chloride are added to 8 ml of oleic acid and 12 ml of octadecene and heated at 160° C. for 1 hour.

[0073] Example 7:

[0074] The only difference from Example 1 is that, in the preparation process of lanthanide fluorescent nanoparticles, step S2 does not perform gradient heating, but directly reacts at 300° C. for 1 hour.

[0075] Example 8:

[0076] The only difference from Example 1 is that polydimethylsiloxane grafting is not performed during the preparation of the lanthanide fluorescent nanoparticles.

[0077] Example 9:

[0078] The only difference from Example 1 is that the lanthanide fluorescent nanoparticles are not core-shell coated with silica.

[0079] Example 10:

[0080] The only difference from Example 1 is that the median particle size of the lanthanide fluorescent nanoparticles is 10 nm.

[0081] Example 11:

[0082] The only difference from Example 1 is that the median particle size of the lanthanide fluorescent nanoparticles is 600 nm.

[0083] Comparative Example 1:

[0084] The only difference from Example 1 is that no lanthanide fluorescent nanoparticles are added to the raw materials.

[0085] Comparative Example 2:

[0086] The only difference from Example 1 is that the added amount of lanthanide fluorescent nanoparticles is 1 part.

[0087] Comparative Example 3:

[0088] The only difference from Example 1 is that the added amount of lanthanide fluorescent nanoparticles is 15 parts.

[0089] Table 1: Performance test of polypropylene masterbatch prepared in Examples 1-8 and Comparative Examples 1-3.

[0090]

[0091]

[0092] In summary, the present invention increases the compatibility of lanthanide fluorescent nanoparticles with polypropylene through core-shell structure modification and surface grafting, enables the nanoparticles to be evenly dispersed in the polypropylene matrix, and improves the overall performance of the composite material.

[0093] The parts of the embodiment herein that are not exhaustive of the midpoint values ​​of the technical scope claimed for protection by the present invention and the new technical solutions formed by equivalent replacement of single or multiple technical features in the technical solutions of the embodiments are also within the scope claimed for protection by the present invention; at the same time, in all the embodiments listed or not listed in the solutions of the present invention, each parameter in the same embodiment merely represents an example of its technical solution (i.e., a feasible solution), and there is no strict coordination and limitation relationship between the parameters, wherein the parameters can be replaced with each other without violating the axioms and the claims of the present invention, unless otherwise stated.

[0094] The technical means disclosed in the solutions of the present invention are not limited to the technical means disclosed in the above technical means, but also include technical solutions composed of any combination of the above technical features. The above is a specific embodiment of the present invention. It should be noted that for those skilled in the art, various improvements and modifications can be made without departing from the principles of the present invention, and such improvements and modifications are also considered to be within the scope of protection of the present invention.

[0095] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Persons skilled in the art may make various modifications, additions, or substitutions to the described specific embodiments without departing from the spirit of the present invention or exceeding the scope of the appended claims.

Claims

1. A polypropylene masterbatch for composite rare earth element non-destructive industrial flaw detection, characterized in that: The polypropylene masterbatch comprises the following raw materials in parts by weight: 60-75 parts of polypropylene, 10-20 parts of a toughening agent, 10-20 parts of a filler, 4-10 parts of lanthanide fluorescent nanoparticles, and 40-60 parts of an auxiliary agent.

2. The polypropylene masterbatch for non-destructive industrial flaw detection of composite rare earth elements according to claim 1, characterized in that: The lanthanide fluorescent nanoparticles are core-shell structures, composed of matrix material NaLuF4, sensitizing ion Yb 3+ , luminescence center Tm 3+ The core is composed of silicon dioxide, which is coated and grafted with polydimethylsiloxane.

3. The polypropylene masterbatch for non-destructive industrial flaw detection of composite rare earth elements according to claim 1, characterized in that: The preparation method of the lanthanide fluorescent nanoparticles comprises the following steps: S1. adding lutetium chloride, ytterbium chloride and thulium chloride to oleic acid and octadecene for heating reaction; S2, then adding sodium hydroxide and ammonium fluoride dissolved in an organic solvent, and performing gradient heating to obtain semi-finished nanoparticles; S3, dissolving the semi-finished nanoparticles in an organic solvent, adding sodium hydroxide and ethyl silicate and heating to react to obtain silica-coated nanoparticles; S4. The silica-coated nanoparticles are centrifuged and then grafted with polydimethylsiloxane to obtain lanthanide fluorescent nanoparticles.

4. The polypropylene masterbatch for non-destructive industrial flaw detection of composite rare earth elements according to claim 3, characterized in that: The mass ratio of lutetium chloride, ytterbium chloride and thulium chloride is (35-45):(8-12):

1.

5. The polypropylene masterbatch for composite rare earth element non-destructive industrial flaw detection according to claim 3, characterized in that: Step S2: gradient heating is firstly heated at 100-125° C. until the methanol is completely volatilized, then heated to 250-350° C., and reacted for 0.5-2.5 hours.

6. The polypropylene masterbatch for non-destructive industrial flaw detection of composite rare earth elements according to any one of claims 1 to 3, characterized in that: The median particle size of lanthanide fluorescent nanoparticles is 50-400nm.

7. The polypropylene masterbatch for non-destructive industrial flaw detection of composite rare earth elements according to claim 1, characterized in that: The filler includes at least one of calcium carbonate, talc and glass fiber.

8. The polypropylene masterbatch for composite rare earth element non-destructive industrial flaw detection according to claim 1, characterized in that: The auxiliary agent includes at least one of a lubricant, a plasticizer, a flame retardant, an antistatic agent, and a stabilizer.

9. A method for preparing polypropylene masterbatch for non-destructive industrial flaw detection of composite rare earth elements as claimed in claim 1, characterized in that: The method comprises the following steps: mixing polypropylene, a toughening agent, a filler, lanthanum fluorescent nanoparticles and an auxiliary agent, and then extruding and granulating the mixture in an extruder.

10. The method for preparing a polypropylene masterbatch for non-destructive industrial flaw detection of composite rare earth elements according to claim 9, characterized in that: The extrusion granulation temperature is 190-230℃.

Images