Laser marking color master batch for improving laser identifiability and preparation method and application thereof

Abstract

The invention relates to the technical field of laser marking materials, in particular to a laser marking color master batch for improving laser recognizability and a preparation method and application thereof. The invention relates to a laser marking color master batch capable of improving laser identifiability, which is prepared from the following raw materials in parts by mass: 30-40 parts of special infrared absorption pigment, 10-15 parts of stabilizer and 45-60 parts of carrier resin, the special infrared absorption pigment is modified nano molybdenum nitride; the stabilizer is a composite antioxidant; the carrier resin is modified polyethylene wax. According to the prepared color master batch for laser marking capable of improving the laser identifiability, the contrast ratio and definition of a laser mark on a light-color or transparent plastic product are obviously improved, and the identification effect of mark information is improved; and meanwhile, on the premise of ensuring the laser identifiability, the color master batch does not influence the original physical properties of a plastic product, and is very suitable for laser marking of a PET film with the thickness of less than or equal to 0.05 mm.

Description

Technical Field

[0001] The present application relates to the technical field of laser marking materials, and in particular to a laser marking masterbatch for improving laser recognition, and a preparation method and application thereof. Background Art

[0002] Existing laser marking masterbatches mostly use traditional chemically synthesized pigments, which suffer from poor photostability, insufficient color consistency, and low contrast on light-colored substrates. They are particularly prone to fading in complex environments or after long-term use, and their low infrared absorption efficiency leads to insufficient marking clarity. Existing improvements involve increasing absorbent concentration or adjusting dispersion, but these can easily damage the plastic substrate and are costly. Therefore, there is an urgent need for a masterbatch that combines efficient laser energy absorption, excellent photostability, and good substrate compatibility. Summary of the Invention

[0003] The purpose of this application is to address the shortcomings of current technologies and provide a laser marking masterbatch with improved laser recognition, as well as its preparation method and application. The laser marking masterbatch prepared in this application significantly improves the contrast and clarity of laser marking on light-colored or transparent plastic products, improving the recognition effect of the marked information. At the same time, while ensuring laser recognition, the masterbatch does not affect the original physical properties of the plastic products, and even improves them in some cases, making it very suitable for laser marking of PET films with a thickness of ≤0.05mm. This application solves three major industry problems in laser marking of ultra-thin materials through a four-fold synergistic mechanism of "light absorption-heat transfer-anti-oxidation-structural enhancement": 1. The contradiction between high precision and high contrast: nanocomposite photothermal materials achieve precise energy localization; 2. Thermal damage control: gradient thermal stability design balances transient high temperature and substrate protection; 3. Processing adaptability: polar interface regulation takes into account dispersion, fluidity and mechanical properties. This technology provides a high-performance, low-cost green marking solution for ultra-thin plastic products in fields such as food packaging and electronic labels.

[0004] In the first aspect, the present application provides a laser marking masterbatch with improved laser recognition, which adopts the following technical solutions: A laser marking masterbatch for improving laser recognition comprises the following raw materials, calculated by weight: 30-40 parts of a special infrared absorbing pigment, 10-15 parts of a stabilizer, and 45-60 parts of a carrier resin. The special infrared absorbing pigment is modified nano-molybdenum nitride; the stabilizer is a composite antioxidant; and the carrier resin is modified polyethylene wax.

[0005] By employing this technical solution, nano-molybdenum nitride is modified and coated with a carbon layer, significantly enhancing its absorption efficiency (especially in the near-infrared band), concentrating the energy in a localized area and forming a regular pore structure. The carbon coating reduces nanoparticle agglomeration, improves the interfacial bonding with the resin matrix, and sharpens the edges of the micropores formed by laser burning, thereby enhancing the contrast of the mark. The surface modification allows for uniform distribution in the resin without the need for additional dispersants, reducing material costs. For example, a composite antioxidant is composed of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], ditetradecyl thiodipropionate, and tris[2,4-di-tert-butylphenyl]phosphite in a mass ratio of 4:3:3. Pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] terminates the chain oxidation reaction by capturing free radicals; ditetradecyl thiodipropionate decomposes peroxides and inhibits secondary oxidation; and tris[2,4-di-tert-butylphenyl]phosphite chelates metal ions, blocking the catalytic oxidation pathway. The three components are compounded in a 4:3:3 ratio to form a gradient antioxidant system that effectively delays resin degradation and pigment deactivation under laser transient high temperatures (200-400°C). 3. Modified polyethylene wax: Maleic anhydride grafting introduces -COOH / -OH groups to enhance compatibility with polar substrates such as PET; styrene copolymer provides a rigid skeleton to balance the material's fluidity. Nano-titanium dioxide modification enhances melt strength and prevents deformation of ultra-thin PET films (≤0.05mm) during processing. It synergizes with molybdenum nitride to enhance laser absorption efficiency and facilitate high-contrast marking. The efficient energy absorption of modified nano-molybdenum nitride and the low thermal conductivity of modified polyethylene wax form an "energy trap," limiting heat diffusion and concentrating laser energy into localized carbonization / foaming, significantly enhancing mark edge sharpness. Polar groups (-OH / -COOH) hydrogen bond with the surface carbon layer of nano-molybdenum nitride, achieving nanoscale dispersion of the inorganic-organic phase and preventing laser scattering losses due to agglomeration. Nano-titanium dioxide and grafted polyethylene wax form a quasi-network structure, enhancing melt elasticity and adapting to high-speed extrusion processing. They also reduce shrinkage, ensuring warpage-free marking of ultra-thin PET films. In summary, this masterbatch achieves a breakthrough balance between laser recognition, processing stability, and substrate compatibility through chemical bonding, physical synergy, and functional complementarity between its components.

[0006] Preferably, the preparation method of the modified nano-molybdenum nitride comprises the following steps: S21, placing 50 parts by mass of nano-molybdenum nitride in 200 parts by mass of 70% sodium hydroxide solution, and then heating at 105-110° C. for 3-4 hours; after the reaction is completed, filtering and drying to obtain hydroxylated nano-molybdenum nitride; S22, dispersing 50 parts by mass of hydroxylated nano-molybdenum nitride in a solution consisting of 200 parts by mass of ethanol and 50 parts by mass of water, stirring for 20 minutes, adding 3-4 parts by mass of a silane coupling agent and 5-6 parts by mass of polyvinyl alcohol, adjusting the pH of the solution to 4.5-5, stirring for 4-5 hours, filtering, washing with anhydrous ethanol three times, freeze-drying, and grinding to obtain silane-modified nano-molybdenum nitride; S23, carbonizing the silane-modified nano-molybdenum nitride obtained in step S22 under a nitrogen atmosphere, grinding, and obtaining nano-molybdenum nitride with a surface coated with a carbon layer, that is, obtaining modified nano-molybdenum nitride.

[0007] By adopting the above technical scheme, S21: hydroxylation treatment, strong alkali etches the surface of molybdenum nitride to generate hydroxyl (-OH) groups and improve surface reaction activity. Dissolve surface impurities and expose the high-purity molybdenum nitride core. The hydroxylated surface provides binding sites for subsequent silane coupling agent grafting. S22: Silane coupling agent modification, the methoxy group of the silane coupling agent condenses with the hydroxylated surface to form a Si-O-Mo bond, and the vinyl end provides a carbon source for subsequent carbonization. Polyvinyl alcohol acts as a steric hindrance to prevent nanoparticles from agglomerating. Weakly acidic conditions promote the hydrolysis and condensation reaction of silane to ensure uniform coating. S23: Carbonization treatment, silane coupling agent and polyvinyl alcohol are pyrolyzed at high temperature to generate an amorphous carbon layer (about 5-10nm thick). The carbon layer fills surface defects and enhances the nanoparticles' resistance to high-temperature oxidation (the carbon layer blocks oxygen diffusion). After grinding, the average particle size is maintained at 60-80nm to avoid particle sintering and growth caused by carbonization. The prepared modified nano-molybdenum nitride exhibits the following benefits: 1. Enhanced laser absorption: The heterojunction effect between the carbon coating (highly graphitized) and molybdenum nitride significantly improves near-infrared (1064nm laser) absorption. The surface carbon layer acts as an "energy converter," efficiently converting light energy into heat, promoting localized carbonization of the resin to form micropores. 2. Improved dispersion stability: The silane coupling agent-modified surface reduces polarity, enabling uniform dispersion with modified polyethylene wax (containing -OH / -COOH) through hydrogen bonding. The carbon layer's physical barrier action inhibits secondary aggregation of nanoparticles during processing. 3. Regulated thermal conductivity: The carbon coating reduces the thermal conductivity of molybdenum nitride, prolonging the laser exposure time and promoting full carbonization of the resin. The carbon layer forms a thermal buffer interface with the resin matrix, preventing localized overheating and thermal damage to the substrate. Synergistically with the composite antioxidant, the carbon layer isolates oxygen diffusion and forms a dual antioxidant barrier with antioxidants (such as phosphites), inhibiting the oxidation of Mo2N to MoO3 at high temperatures. Compatibility with modified polyethylene wax is enhanced, and the vinyl groups of the silane coupling agent covalently bond with the styrene-grafted polyethylene wax to form a "core-shell-chain" structure: core: carbon-coated molybdenum nitride; shell: grafted polyethylene wax; chain: polyethylene wax main chain interspersed with the resin matrix. This structure enables the masterbatch to maintain shear-thinning properties when melted, making it suitable for ultra-thin PET film processing. Synergistically enhancing the effect with nano-titanium dioxide, titanium dioxide (TiO2) produces a plasma resonance effect under the action of laser, forming a multi-level photothermal conversion network with carbon-coated molybdenum nitride: TiO2 absorbs ultraviolet-visible light, and molybdenum nitride absorbs near-infrared light, broadening the spectral response range. The two work together to enhance marking contrast. In summary, this preparation method achieves integrated function-structure regulation through the coordinated design of chemical modification and physical coating, and is a key innovation in solving the problem of high-precision laser marking of ultra-thin materials.

[0008] Preferably, the average particle size of the nano-molybdenum nitride particles is 60-80 nanometers.

[0009] Preferably, in step S22, the silane coupling agent is vinyl tris(β-methoxyethoxy)silane.

[0010] Preferably, in step S23, the process conditions of the carbonization treatment are: heating to 500-600°C at a heating rate of 3-5°C / min and keeping the temperature for 1-2h.

[0011] Preferably, the composite antioxidant is composed of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], ditetradecyl thiodipropionate and tris[2,4-di-tert-butylphenyl]phosphite in a mass ratio of 4:3:3.

[0012] By employing this technical solution, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] donates hydrogen atoms through the phenolic hydroxyl group (-OH), terminating the alkyl radicals (R·) and peroxyl radicals (ROO·) in the oxidative chain reaction. The bulky tert-butyl substituent provides steric hindrance, delaying the oxidative deactivation of the phenolic hydroxyl group at high temperatures (>200°C). Its decomposition products activate the peroxide decomposition ability of thiodipropionate. Ditetradecyl thiodipropionate reduces hydroperoxides (ROOH) to inert alcohols (ROH) via a thioether bond (-SS-), blocking free radical regeneration. The long-chain tetradecyl ester group reduces system viscosity and promotes uniform heat distribution during processing. This creates a "hydrogen donor-acceptor" cycle with pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], extending the antioxidant effect. Tris[2,4-di-tert-butylphenyl]phosphite chelates metal ions in processing equipment or raw materials through the lone pair electrons of its phosphorus atom, inhibiting catalytic oxidation. It also converts ROOH into non-radical products (such as ketones). The large sterically hindered phenyl group enhances the molecule's hydrolytic stability, making it suitable for humidity-sensitive PET processing environments. It preferentially decomposes under the transient high temperatures of laser light (300-500°C), forming a phosphate protective film that blocks oxygen diffusion. Pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate captures free radicals, forming a quinone-like structure that can accept hydrogen atoms from ditetradecyl thiodipropionate to regenerate a reactive phenolic hydroxyl group. The sulfide bond of ditetradecyl thiodipropionate is oxidized to a sulfoxide, which is then reduced and regenerated by tris[2,4-di-tert-butylphenyl]phosphite. The polar phenolic hydroxyl groups of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] adsorb onto the carbon surface of modified nano-molybdenum nitride, reducing oxidation at the pigment-resin interface. The non-polar phenyl groups of tris[2,4-di-tert-butylphenyl]phosphite are compatible with the styrene segments of the modified polyethylene wax, forming a uniformly dispersed antioxidant network. The long-chain alkyl groups of ditetradecyl thiodipropionate entangle with the polyethylene wax backbone, reducing the risk of small-molecule antioxidants migrating to the product surface. In summary, this composite antioxidant system, through multi-mechanism synergy and functional gradient design, achieves full-cycle oxidation protection for masterbatches under dynamic thermal environments, making it one of the core technologies for ensuring the stability of high-precision laser marking on ultra-thin PET films.

[0013] Preferably, the preparation method of the modified polyethylene wax comprises the following steps: S71. Place 10 parts by mass of titanium dioxide having an average particle size of 25 nm in 150 parts by mass of a 70% sodium hydroxide solution, and heat the mixture at 105-110° C. for 3-4 hours. After the reaction is complete, filter and dry the mixture to obtain hydroxylated titanium dioxide. S72. Add 1.2 parts of initiator, 6-8 parts of maleic anhydride, 2-3 parts of styrene and 6-8 parts of hydroxylated titanium dioxide to 100 parts of polyethylene wax in parts by mass, then heat to 160-170°C for grafting modification, stir the reaction for 8-10 hours, and cool to room temperature to obtain modified polyethylene wax.

[0014] By adopting the above technical scheme, S71: Preparation of hydroxylated titanium dioxide, strong base etches the titanium dioxide surface to generate hydroxyl (-OH) groups, improving surface reactivity; dissolving surface impurities to expose high-purity TiO2 crystals; the hydroxylated surface provides chemical bonding sites for subsequent grafting modification (such as esterification reaction with maleic anhydride). S72: Graft copolymerization modification, initiators such as benzoyl peroxide (BPO) decompose to produce free radicals, triggering chain scission reactions of the polyethylene wax backbone, forming active sites; maleic anhydride grafts -COOH groups, and styrene copolymerization enhances molecular chain rigidity; hydroxylated TiO2 is dispersed in the resin matrix through the dual effects of chemical bonds (ester bonds) and physical adsorption. Maleic anhydride grafts carboxylic acid groups (-COOH) on the polyethylene wax backbone through esterification reaction, significantly improving compatibility with polar substrates such as PET; the carboxylic acid groups condense with the -OH groups on the surface of hydroxylated TiO2 to form TiO2-wax interface chemical bonds. The rigid structure of the styrene group's benzene ring inhibits the folding of the polyethylene wax molecular chain, improving melt strength; it forms an alternating copolymer with maleic anhydride, optimizing the grafting rate. Nano-TiO2 (25nm) produces a plasma resonance effect under the action of laser light, synergistically broadening the light absorption band (ultraviolet to near-infrared) with modified molybdenum nitride; the high thermal conductivity of TiO2 promotes local heat diffusion, preventing burn-through of the PET film. The -COOH of maleic anhydride forms an ester bond with the -OH on the TiO2 surface, constructing a "wax-TiO2" covalent connection; styrene provides spatial barrier: the hydrophobicity of the benzene ring is compatible with the polyethylene wax backbone, inhibiting TiO2 agglomeration. In summary, this preparation method achieves a triple breakthrough in the functionality, processability, and stability of the carrier resin through the coordinated design of chemical grafting and nanocomposite, and is one of the core innovations in high-precision laser marking technology for ultra-thin materials.

[0015] Preferably, the initiator is benzoyl peroxide.

[0016] In a second aspect, the present application provides a method for preparing a laser marking masterbatch with improved laser recognition, using the following technical solution: As a general technical concept, the present application also provides a method for preparing the above-mentioned laser marking masterbatch with improved laser recognition, comprising the following steps: S91. Premix the special infrared absorbing pigment and the stabilizer according to parts by mass, add the mixture to the molten carrier resin, and stir evenly to obtain a mixture; S92. The obtained mixture is put into a twin-screw extruder granulator for extrusion granulation, cooling, crushing and screening to obtain a laser marking masterbatch with a particle size of 1-3 mm for improving laser recognition, wherein the temperatures of each section of the screw of the twin-screw extruder granulator from the feed port to the head are 240-250℃, 250-260℃, 270-280℃, 260-270℃ and 250-260℃ respectively; the screw speed is 300-350rpm.

[0017] In a third aspect, the present application provides an application of a laser marking masterbatch for improving laser recognition, using the following technical solution: As a general technical concept, the present application also provides the application of the above-mentioned laser marking masterbatch for improving laser recognition, which is specifically applied to laser marking of PET films with a thickness of ≤0.05 mm.

[0018] In summary, the beneficial technical effects of this application are: 1. High-contrast markings The modified nano-molybdenum nitride (carbon coating) and nano-titanium dioxide work synergistically to increase the light absorption rate in the near-infrared (1064nm) to ultraviolet (<380nm) band to more than 95%, while improving the laser energy conversion efficiency and producing a uniform microporous structure in the marked area.

[0019] 2. Adaptability to ultra-thin materials The melt strength and flow balance of modified polyethylene wax, combined with the thermal conductivity regulation of TiO2, enable precise processing of PET films with a thickness of ≤0.05mm, reduce the thermal deformation rate in the burning area, and avoid warping or perforation.

[0020] 3. Excellent compatibility of substrate performance Physical properties are retained. When the masterbatch addition amount is ≤5%, the tensile strength retention rate of PET film is ≥98%, and the elongation at break has no significant change.

[0021] A breakthrough in thermal stability: modified polyethylene wax and antioxidants work synergistically to ensure stability under high-temperature processing (250-280°C) and laser transient thermal shock (300-500°C).

[0022] 4. Weather resistance After 1000 hours of UV aging test, the color difference ΔE≤1.5. DETAILED DESCRIPTION

[0023] The embodiments of the present application will be described in detail below with reference to the examples, but it will be understood by those skilled in the art that the following examples are merely illustrative of the present application and should not be considered as limiting the scope of the present application. In the examples, if specific conditions are not specified, the conditions are carried out according to conventional conditions or manufacturer recommendations. The reagents or instruments used are not specified by the manufacturer and are conventional products that can be purchased commercially.

[0024] In the following examples and preparation examples, 1 part means 100 g.

[0025] Preparation Example 1 Preparation of modified nano-molybdenum nitride The preparation method of modified nano-molybdenum nitride comprises the following steps: S21, placing 50 parts by mass of nano-molybdenum nitride with an average particle size of 70 nanometers in 200 parts by mass of a 70% sodium hydroxide solution, and then heating at 105° C. for 4 hours; after the reaction is complete, filtering and drying to obtain hydroxylated nano-molybdenum nitride; S22, dispersing 50 parts by mass of hydroxylated nano-molybdenum nitride in a solution consisting of 200 parts by mass of ethanol and 50 parts by mass of water, stirring for 20 minutes, then adding 3 parts by mass of vinyltri(β-methoxyethoxy)silane and 6 parts by mass of polyvinyl alcohol, adjusting the pH of the solution to 4.5, stirring for 4 hours, filtering, washing with anhydrous ethanol three times, freeze-drying, and grinding to obtain silane-modified nano-molybdenum nitride; S23. The silane-modified nano-molybdenum nitride obtained in step S22 is carbonized under a nitrogen atmosphere. The process conditions of the carbonization treatment are: heating to 500° C. at a rate of 3° C. / min and keeping warm for 2 h, grinding, and sieving to obtain nano-molybdenum nitride with an average particle size of 70 nm and a surface-coated carbon layer, namely, modified nano-molybdenum nitride.

[0026] Preparation Example 2 Preparation of modified nano-molybdenum nitride The preparation method of modified nano-molybdenum nitride comprises the following steps: S21, placing 50 parts by mass of nano-molybdenum nitride with an average particle size of 70 nanometers in 200 parts by mass of a 70% sodium hydroxide solution, and then heating at 110° C. for 3 hours; after the reaction is completed, filtering and drying to obtain hydroxylated nano-molybdenum nitride; S22, dispersing 50 parts by mass of hydroxylated nano-molybdenum nitride in a solution consisting of 200 parts by mass of ethanol and 50 parts by mass of water, stirring for 20 minutes, then adding 4 parts by mass of vinyltri(β-methoxyethoxy)silane and 5 parts by mass of polyvinyl alcohol, adjusting the pH of the solution to 5, stirring for 5 hours, filtering, washing with anhydrous ethanol three times, freeze-drying, and grinding to obtain silane-modified nano-molybdenum nitride; S23. The silane-modified nano-molybdenum nitride obtained in step S22 is carbonized under a nitrogen atmosphere. The process conditions of the carbonization treatment are: heating to 600° C. at a rate of 5° C. / min and keeping warm for 1 hour, grinding, and sieving to obtain nano-molybdenum nitride with an average particle size of 70 nanometers and a surface-coated carbon layer, namely, modified nano-molybdenum nitride.

[0027] Preparation Example 3 Preparation of modified nano-molybdenum nitride The preparation method of modified nano-molybdenum nitride comprises the following steps: S21, placing 50 parts by mass of nano-molybdenum nitride with an average particle size of 70 nanometers in 200 parts by mass of a 70% sodium hydroxide solution, and then heating the mixture at 108° C. for 3.4 hours; after the reaction is complete, filtering and drying the mixture to obtain hydroxylated nano-molybdenum nitride; S22, dispersing 50 parts by mass of hydroxylated nano-molybdenum nitride in a solution consisting of 200 parts by mass of ethanol and 50 parts by mass of water, stirring for 20 minutes, adding 3.4 parts by mass of vinyltris(β-methoxyethoxy)silane and 5.6 parts by mass of polyvinyl alcohol, adjusting the pH of the solution to 4.7, stirring for 4.5 hours, filtering, washing with anhydrous ethanol three times, freeze-drying, and grinding to obtain silane-modified nano-molybdenum nitride; S23. The silane-modified nano-molybdenum nitride obtained in step S22 is carbonized under a nitrogen atmosphere. The process conditions of the carbonization treatment are: heating to 550° C. at a rate of 4° C. / min and keeping warm for 1.6 h, grinding, and sieving to obtain nano-molybdenum nitride with an average particle size of 70 nm and a surface-coated carbon layer, namely, modified nano-molybdenum nitride.

[0028] Preparation of Comparative Example 1 Preparation of Modified Nano-Molybdenum Nitride The preparation method of modified nano-molybdenum nitride comprises the following steps: S21, placing 50 parts by mass of nano-molybdenum nitride with an average particle size of 70 nanometers in 200 parts by mass of a 70% sodium hydroxide solution, and then heating the mixture at 108° C. for 3.4 hours; after the reaction is complete, filtering and drying the mixture to obtain hydroxylated nano-molybdenum nitride; S22. Disperse 50 parts of hydroxylated nano-molybdenum nitride in a solution consisting of 200 parts of ethanol and 50 parts of water, stirring for 20 minutes, then add 3.4 parts of vinyl tris(β-methoxyethoxy)silane and 5.6 parts of polyvinyl alcohol, adjust the pH of the solution to 4.7, stir for 4.5 hours, filter, wash three times with anhydrous ethanol, freeze-dry and grind, and sieve to obtain modified nano-molybdenum nitride with an average particle size of 70 nanometers.

[0029] Preparation Example 4 Preparation of modified polyethylene wax The preparation method of modified polyethylene wax comprises the following steps: S71. Add 10 parts by mass of titanium dioxide having an average particle size of 25 nm to 150 parts by mass of a 70% sodium hydroxide solution, and heat the mixture at 107° C. for 3.4 hours. After the reaction is complete, filter and dry the mixture to obtain hydroxylated titanium dioxide. S72. Add 1.2 parts of benzoyl peroxide, 7 parts of maleic anhydride, 3 parts of styrene and 7 parts of hydroxylated titanium dioxide to 100 parts of polyethylene wax in parts by mass, then raise the temperature to 168°C for grafting modification, stir the reaction for 9 hours, and cool to room temperature to obtain modified polyethylene wax.

[0030] Preparation of Comparative Example 2: Preparation of Modified Polyethylene Wax The preparation method of modified polyethylene wax comprises the following steps: S72. Add 1.2 parts of benzoyl peroxide, 7 parts of maleic anhydride and 3 parts of styrene to 100 parts of polyethylene wax in parts by mass, then raise the temperature to 168°C for graft modification, stir the reaction for 9 hours, and cool to room temperature to obtain modified polyethylene wax.

[0031] Example 1 A laser marking masterbatch for improving laser recognition comprises the following raw materials, measured in parts by mass: 30 parts of a special infrared absorbing pigment, 10 parts of a stabilizer, and 45 parts of a carrier resin, wherein the special infrared absorbing pigment is the modified nano-molybdenum nitride prepared in Preparation Example 1; the carrier resin is the modified polyethylene wax prepared in Preparation Example 4; and the composite antioxidant is composed of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, ditetradecyl thiodipropionate, and tris[2,4-di-tert-butylphenyl]phosphite in a mass ratio of 4:3:3. The method for preparing the laser marking masterbatch with improved laser recognition comprises the following steps: S91. Premix the special infrared absorbing pigment and the stabilizer according to parts by mass, add the mixture to the molten carrier resin, and stir evenly to obtain a mixture; S92. The obtained mixture is put into a twin-screw extruder granulator for extrusion granulation, cooling, crushing and screening to obtain a laser marking masterbatch with a particle size of 1 mm for improving laser recognition, wherein the temperatures of each section of the screw of the twin-screw extruder granulator from the feed port to the head are 240°C, 250°C, 270°C, 260°C and 250°C respectively; the screw speed is 300rpm.

[0032] Example 2 A laser marking masterbatch for improving laser recognition comprises the following raw materials, measured by weight: 40 parts of a special infrared absorbing pigment, 15 parts of a stabilizer, and 60 parts of a carrier resin, wherein the special infrared absorbing pigment is the modified nano-molybdenum nitride prepared in Preparation Example 2; the carrier resin is the modified polyethylene wax prepared in Preparation Example 4; and the composite antioxidant is composed of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, ditetradecyl thiodipropionate, and tris[2,4-di-tert-butylphenyl]phosphite in a weight ratio of 4:3:3. The method for preparing the laser marking masterbatch with improved laser recognition comprises the following steps: S91. Premix the special infrared absorbing pigment and the stabilizer according to parts by mass, add the mixture to the molten carrier resin, and stir evenly to obtain a mixture; S92. The obtained mixture is put into a twin-screw extruder granulator for extrusion granulation, cooling, crushing and screening to obtain a laser marking masterbatch with a particle size of 3 mm for improving laser recognition, wherein the temperatures of each section of the screw of the twin-screw extruder granulator from the feed port to the head are 250°C, 260°C, 280°C, 270°C and 260°C respectively; the screw speed is 350rpm.

[0033] Example 3 A laser marking masterbatch for improving laser recognition, comprising the following raw materials, calculated by weight: 35 parts of a special infrared absorbing pigment, 13 parts of a stabilizer, and 53 parts of a carrier resin, wherein the special infrared absorbing pigment is the modified nano-molybdenum nitride prepared in Preparation Example 3; the carrier resin is the modified polyethylene wax prepared in Preparation Example 4; and the composite antioxidant is composed of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, ditetradecyl thiodipropionate, and tris[2,4-di-tert-butylphenyl]phosphite in a weight ratio of 4:3:3. The method for preparing the laser marking masterbatch with improved laser recognition comprises the following steps: S91. Premix the special infrared absorbing pigment and the stabilizer according to parts by mass, add the mixture to the molten carrier resin, and stir evenly to obtain a mixture; S92. The obtained mixture is put into a twin-screw extruder granulator for extrusion granulation, cooling, crushing and screening to obtain a laser marking masterbatch with a particle size of 1.5 mm for improving laser recognition, wherein the temperatures of each section of the screw of the twin-screw extruder granulator from the feed port to the head are 245°C, 255°C, 275°C, 265°C and 255°C respectively; the screw speed is 320rpm.

[0034] Comparative Example 1 The same as Example 3, except that the special infrared absorbing pigment is the modified nano-molybdenum nitride prepared in Comparative Example 1.

[0035] Comparative Example 2 The same as Example 3, except that the carrier resin is the modified polyethylene wax prepared in Comparative Example 2.

[0036] Comparative Example 3 The same as Example 3, except that the composite antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0037] Comparative Example 4 The same as Example 3, except that the composite antioxidant is ditetradecyl thiodipropionate.

[0038] Comparative Example 5 The same as Example 3, except that the composite antioxidant is tris[2,4-di-tert-butylphenyl]phosphite.

[0039] Performance Testing 1. Weather resistance test: Samples of the laser marking masterbatches for improving laser recognition prepared in Examples 1 to 3 and Comparative Examples 1 to 5 were taken, and standard test strips were made. The test was conducted for 1000 hours in accordance with GB / T 16422.3-2022 (UV lamp aging test). Each sample was tested three times, and the average of the results was taken. The results are shown in Table 1. 2. Samples of the laser marking masterbatches for improving laser recognition prepared in Examples 1 to 3 and Comparative Examples 1 to 5 were taken, mixed with PET resin at a mass ratio of 3:97, and then put into a twin-screw extruder for extrusion granulation. PET films with a thickness of 0.05 mm were then prepared using a film-making equipment. Similarly, pure PET resin was used to prepare a PET film with a thickness of 0.05 mm (as a test reference sample). The following performance tests were performed, with each sample tested three times and the results averaged. The results are shown in Table 1. Tensile strength retention rate: The amount used to characterize the compatibility of the masterbatch with the PET resin is used to test the tensile strength according to ASTM D638 and calculate the tensile strength retention rate; Laser marking effect: Laser marking is divided into five levels: A, B, C, D, and E according to the clarity from clear to fuzzy, with A being the best and E being the worst. It is judged visually. Laser marking equipment: laser wavelength 1064nm, power 50W; Marking contrast, tested according to ISO 2834-2 standard.

[0040] Table 1 Performance test project Weather resistance ΔE Laser marking effect Tensile strength retention rate / % Marker contrast / % Example 1 1.5 A 98.1 85 Example 2 1.3 A 98.7 87 Example 3 1.1 A 99.5 88 Comparative Example 1 1.4 C 99.3 65 Comparative Example 2 2.9 B 94.6 71 Comparative Example 3 1.8 B 99.3 83 Comparative Example 4 2.0 B 98.9 81 Comparative Example 5 2.1 B 98.6 79 Analyzing the data in Table 1, we can see that: 1) The laser marking masterbatches for improving laser recognition prepared in Examples 1 to 3 significantly enhance the contrast and clarity of laser marking on light-colored or transparent plastic products, thereby improving the recognition effect of the marked information. Furthermore, while ensuring laser recognition, the masterbatches do not affect the original physical properties of the plastic products, and are therefore very suitable for laser marking of PET films with a thickness of ≤0.05 mm.

[0041] 2) A comparative analysis of the performance of the laser marking masterbatch for improving laser recognition obtained in Example 3 and Comparative Example 1 shows that the modified nano-molybdenum nitride prepared in the present application has the following effects: 1. Enhanced laser absorption, the heterojunction effect of the carbon coating layer (high degree of graphitization) and molybdenum nitride significantly improves the near-infrared (1064nm laser) absorption rate. The surface carbon layer acts as an "energy converter", efficiently converting light energy into heat energy, promoting local carbonization of the resin to form micropores. 2. Improved dispersion stability, the surface polarity modified by the silane coupling agent is reduced, and uniform dispersion is achieved through hydrogen bonding with modified polyethylene wax (containing -OH / -COOH). The physical barrier effect of the carbon layer inhibits the secondary agglomeration of nanoparticles during the processing process. 3. Thermal conduction regulation, the carbon coating layer reduces the thermal conductivity of molybdenum nitride, prolongs the laser action time, and promotes sufficient carbonization of the resin. The carbon layer forms a thermal buffer interface with the resin matrix to avoid local overheating and thermal damage to the substrate. In synergy with the composite antioxidant, the carbon layer isolates oxygen diffusion and forms a dual anti-oxidation barrier with antioxidants (such as phosphites), inhibiting the oxidation of Mo2N to MoO3 at high temperatures. In summary, the prepared modified nano-molybdenum nitride, through the coordinated design of chemical modification and physical coating, achieves integrated function-structure regulation, significantly improving the contrast and clarity of laser marking on light-colored or transparent plastic products, and improving the recognition effect of the marked information. At the same time, while ensuring laser recognition, the masterbatch does not affect the original physical properties of the plastic products.

[0042] 3) The comparative analysis of the performance of the laser marking masterbatch for improving laser recognition prepared in Example 3 and Comparative Example 2 shows that the modified polyethylene wax prepared in this application is formed by graft copolymerization of polyethylene wax, maleic anhydride and styrene, and is doped with nano-titanium dioxide. Maleic anhydride grafts carboxylic acid groups (-COOH) on the polyethylene wax backbone through esterification reaction, significantly improving the compatibility with polar substrates such as PET; the carboxylic acid groups condense with the -OH on the surface of hydroxylated TiO2 to form TiO2-wax interface chemical bonds. The rigid structure of the benzene ring of the styrene group inhibits the folding of the polyethylene wax molecular chain and improves the melt strength; at the same time, the nano-modification of the polyethylene wax with nano-titanium dioxide improves the thermal stability of the modified polyethylene wax, thereby significantly improving the contrast and clarity of laser marking on light-colored or transparent plastic products, and improving the recognition effect of the marked information; at the same time, under the premise of ensuring laser recognition, the masterbatch does not affect the original physical properties of the plastic products.

[0043] 4) A comparative analysis of the performance of the laser marking masterbatch for improving laser recognition obtained in Example 3 and Comparative Examples 3 to 5 shows that the composite antioxidant is composed of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, ditetradecyl thiodipropionate and tris[2,4-di-tert-butylphenyl]phosphite in a mass ratio of 4:3:3. The combined effect of these three ingredients further improves the overall performance of the masterbatch.

[0044] The above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit the present application. Although the above embodiments provide a detailed description of the present application, relevant technical personnel should understand that the specific implementation methods of the present application can still be modified or replaced by equivalents. Any modifications and equivalent replacements that do not depart from the spirit and scope of the present application should be included in the scope of the claims of the present application.

Claims

1. A laser marking masterbatch for improving laser recognition, characterized in that: The preparation raw materials include the following by mass: 30-40 parts of special infrared absorbing pigment, 10-15 parts of stabilizer, and 45-60 parts of carrier resin, wherein the special infrared absorbing pigment is modified nano-molybdenum nitride; the stabilizer is a composite antioxidant; and the carrier resin is modified polyethylene wax.

2. The laser marking masterbatch for improving laser recognition according to claim 1, characterized in that: The preparation method of the modified nano-molybdenum nitride comprises the following steps: S21, placing 50 parts by mass of nano-molybdenum nitride in 200 parts by mass of 70% sodium hydroxide solution, and then heating at 105-110° C. for 3-4 hours; after the reaction is completed, filtering and drying to obtain hydroxylated nano-molybdenum nitride; S22, dispersing 50 parts by mass of hydroxylated nano-molybdenum nitride in a solution consisting of 200 parts by mass of ethanol and 50 parts by mass of water, stirring for 20 minutes, adding 3-4 parts by mass of a silane coupling agent and 5-6 parts by mass of polyvinyl alcohol, adjusting the pH of the solution to 4.5-5, stirring for 4-5 hours, filtering, washing with anhydrous ethanol three times, freeze-drying, and grinding to obtain silane-modified nano-molybdenum nitride; S23, carbonizing the silane-modified nano-molybdenum nitride obtained in step S22 under a nitrogen atmosphere, grinding, and obtaining nano-molybdenum nitride with a surface coated with a carbon layer, that is, obtaining modified nano-molybdenum nitride.

3. The laser marking masterbatch for improving laser recognition according to claim 2, characterized in that: The average particle size of the nano-molybdenum nitride particles is 60-80 nanometers.

4. The laser marking masterbatch for improving laser recognition according to claim 2, characterized in that: In step S22 , the silane coupling agent is vinyl tris(β-methoxyethoxy)silane.

5. The laser marking masterbatch for improving laser recognition according to claim 2, characterized in that: In step S23, the process conditions of the carbonization treatment are: heating to 500-600°C at a heating rate of 3-5°C / min and keeping the temperature for 1-2 hours.

6. The laser marking masterbatch for improving laser recognition according to claim 1, characterized in that: The composite antioxidant consists of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], ditetradecyl thiodipropionate and tris[2,4-di-tert-butylphenyl]phosphite in a mass ratio of 4:3:

3.

7. The laser marking masterbatch for improving laser recognition according to claim 1, characterized in that: The preparation method of the modified polyethylene wax comprises the following steps: S71. Place 10 parts by mass of titanium dioxide having an average particle size of 25 nm in 150 parts by mass of a 70% sodium hydroxide solution, and heat the mixture at 105-110° C. for 3-4 hours. After the reaction is complete, filter and dry the mixture to obtain hydroxylated titanium dioxide. S72. Add 1.2 parts of initiator, 6-8 parts of maleic anhydride, 2-3 parts of styrene and 6-8 parts of hydroxylated titanium dioxide to 100 parts of polyethylene wax in parts by mass, then heat to 160-170°C for grafting modification, stir the reaction for 8-10 hours, and cool to room temperature to obtain modified polyethylene wax.

8. The laser marking masterbatch for improving laser recognition according to claim 7, characterized in that: The initiator is benzoyl peroxide.

9. A method for preparing a laser marking masterbatch with improved laser recognition according to any one of claims 1 to 8, characterized in that: The following steps are involved: S91. Premix the special infrared absorbing pigment and the stabilizer according to parts by mass, add the mixture to the molten carrier resin, and stir evenly to obtain a mixture; S92. The obtained mixture is put into a twin-screw extruder granulator for extrusion granulation, cooling, crushing and screening to obtain a laser marking masterbatch with a particle size of 1-3 mm for improving laser recognition, wherein the temperatures of each section of the screw of the twin-screw extruder granulator from the feed port to the head are 240-250℃, 250-260℃, 270-280℃, 260-270℃ and 250-260℃ respectively; the screw speed is 300-350rpm.

10. An application of a laser marking masterbatch for improving laser recognition according to any one of claims 1 to 8, characterized in that: Applicable to laser marking of PET films with thickness ≤ 0.05mm.