High-end printing ink coating for metal printing based on polyvinyl chloride resin and preparation method of high-end printing ink coating

Abstract

The invention relates to the technical field of printing ink coatings, in particular to a high-end printing ink coating for metal printing based on polyvinyl chloride resin and a preparation method of the high-end printing ink coating. The composite material is composed of the following raw materials in parts by weight: 28-42 parts of a core-shell PVC matrix; 12 to 28 parts of double-shell metal powder; 8 to 16 parts of a cage type auxiliary agent; 22 to 38 parts of a reaction solvent; 1.2 to 3.5 parts of a rheological additive; and 2.5-6 parts of an anchoring auxiliary agent. According to the high-end printing ink coating for metal printing based on the polyvinyl chloride resin, through molecular structure design and component synergistic modification, a core-shell structure polyvinyl chloride film-forming substrate is adopted, and the rigidity and flexibility of a coating are synchronously achieved; multiple effects of blocking, discoloration prevention, matrix compatibility, sedimentation prevention, interface anchoring and adhesive force improvement are achieved through the metal effect pigment of the double-shell structure, and the specular glossiness and the storage stability are greatly improved; and a monomolecular multifunctional cage type auxiliary agent is adopted, so that the compatibility defect of compounding of multiple auxiliary agents is avoided, and the synergistic interaction of light stability, heat stability, leveling and anchoring is synchronously realized.

Description

Technical Field

[0001] This invention relates to the field of printing ink and coating technology, specifically to a high-end metal printing ink and coating based on polyvinyl chloride resin and its preparation method. Background Technology

[0002] Metal printing inks and coatings are special functional materials used for printing on the surfaces of metal substrates such as tinplate, aluminum foil, and stainless steel. They are widely used in food metal packaging, daily chemical metal containers, home appliance decorative panels, metal signs, and other fields. They combine decorative, protective, and printability properties, and are one of the core materials in the deep processing industry chain of metal products. Furthermore, polyvinyl chloride resin is a commonly used film-forming matrix for metal printing inks due to its excellent film-forming properties, chemical resistance, and cost advantages.

[0003] However, existing metal printing inks based on polyvinyl chloride (PVC) resin generally have significant drawbacks: First, PVC resin inherently has high low-temperature brittleness, making the coating prone to cracking and ink loss during bending and stamping of metal substrates, resulting in insufficient adhesion at the metal substrate interface; second, metallic effect pigments are prone to oxidation and discoloration, and turn black upon contact with sulfur, exhibiting poor compatibility with PVC resins, easily settling and stratifying during storage, and exhibiting poor gloss stability between batches; third, solvent-based systems have high volatile organic compound content, resulting in insufficient environmental compliance, and solvent residues can easily lead to coating re-adhesion and decreased weather resistance; fourth, multi-agent compound systems have poor compatibility, easily leading to agent migration and precipitation, resulting in coating fogging and performance degradation; fifth, the preparation process relies on intermittent production, resulting in large fluctuations in fineness and viscosity, unstable printability, and difficulty in adapting to high-speed, high-precision metal printing processes.

[0004] Based on this, the present invention provides a high-end coating for metal printing ink based on polyvinyl chloride resin and its preparation method, so as to solve the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of this invention is to provide a high-end coating for metal printing ink based on polyvinyl chloride resin and its preparation method, thereby solving the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention proposes a high-end coating for metal printing ink based on polyvinyl chloride resin, which is composed of the following raw materials in parts by weight: core-shell PVC matrix: 28-42 parts; Bishell metal powder: 12-28 parts; Cage-type additive: 8-16 parts; Reaction solvent: 22-38 parts; Rheology modifier: 1.2-3.5 parts; Anchoring agent: 2.5-6 parts.

[0007] Preferably, the core-shell PVC matrix is ​​composed of a core layer and a shell layer, wherein the core layer is a highly cross-linked vinyl chloride-divinylbenzene copolymer microsphere, and the shell layer is a low-cross-linked gradient functionalized vinyl chloride-monobutyl maleate-glycidyl methacrylate terpolymer segment, wherein the core layer is 16-24 parts by weight and the shell layer is 12-18 parts by weight. The core layer has a number-average molecular weight of 80,000-120,000, a crosslinking degree of 12%-18%, and in-situ embedded hindered phenolic anti-aging groups. The shell has a number-average molecular weight of 20,000-35,000, and from the core to the shell, the phosphate anchoring groups, epoxy reactive groups, and hydroxyl compatible groups are distributed in a gradient increasing manner, with a grafting rate of 25%-35%.

[0008] Preferably, the double-shell metal powder consists of a core, an inner shell, and an outer shell. The core is a floating aluminum-silver powder and a silane-modified copper-zinc alloy powder that have been activated by plasma surface treatment. The inner shell is a dense nano-silica layer prepared by atomic layer deposition. The outer shell is a polydopamine-mediated polyvinyl chloride segment grafted bifunctional layer. The core contains 9-18 parts by weight of floating aluminum silver powder and 3-10 parts by weight of silane-modified copper-zinc alloy powder; The inner shell is 50-80 nm thick and has no pinholes. The outer shell is 100-150 nm thick and has pH-responsive carboxyl groups on its surface; The core has a surface hydroxyl content of ≥8% after plasma activation.

[0009] Preferably, the cage-type additive has an octavinyl cage-type silsesquioxane as its core, with vinyl chloride-acrylate copolymer segments grafted at the apex, and hindered amine light-stabilizing groups, epoxy heat-stabilizing groups, and phosphate anchoring groups grafted at the remaining apex. The octavinyl cage-like silsesquioxane accounts for 30%-45% by weight, the vinyl chloride-acrylate copolymer segment accounts for 35%-50% by weight, and the total weight of functional groups accounts for 10%-25% by weight. The cage-type additives have a number-average molecular weight of 15,000-25,000 and a compatibility of ≥99.5% with the core-shell PVC matrix.

[0010] Preferably, the reaction solvent is a mixture of a non-reactive gradient volatile solvent and a reactive solvent in a mass ratio of 4:6-5:5; The non-reactive gradient volatile solvent is composed of dimethyl carbonate, propylene glycol methyl ether acetate, and high-boiling-point environmentally friendly solvent D40 in a weight ratio of 6-12:8-14:5-8, with boiling points of 90℃, 145℃, and 200-220℃ respectively. The reactive solvent is a mixture of glycerol methacrylate and vinyl ethylene carbonate in a weight ratio of 3:2 to 2:3. Both glycerol methacrylate and vinyl ethylene carbonate can undergo free radical copolymerization with the core-shell PVC matrix.

[0011] Preferably, the rheology modifier is a compound of polyether-modified polysiloxane leveling agent, acrylate defoamer, hydrogenated castor oil thixotropic agent and fluorinated mica antiflocculation agent in a weight ratio of 0.4-1.2:0.3-0.8:0.5-1.5:0.2-0.6. The fluorinated mica antiflocculation agent has a particle size of 0.5-1μm and a volume resistivity of ≥10¹²Ω·cm.

[0012] Preferably, the anchoring aid is a compound of phosphate-modified chloroacetic acid resin and titanate coupling agent in a weight ratio of 1.5-3.5:1-2.5; The phosphate-modified vinyl acetate resin is a terpolymer of vinyl chloride-vinyl acetate-diphenyl phosphate, with a phosphate group content of 3.5%-5.5% and a number average molecular weight of 30,000-45,000. The titanate coupling agent is isopropyltris(stearoyl) titanate.

[0013] Preferably, the preparation method of the core-shell PVC matrix is ​​as follows: vinyl chloride, divinylbenzene, and hindered phenol monomer are added to a reaction vessel and polymerized at 65-75℃ and 0.3-0.5MPa for 2-3 hours to obtain core layer microspheres; Add monobutyl maleate, glycidyl methacrylate, and initiator to the reactor, heat to 80-85℃, continue polymerization for 1.5-2 hours, control the shell grafting rate, cool, crush and sieve to obtain core-shell PVC matrix; The core layer contains 0.8%-1.5% hindered phenolic anti-aging groups, and the shell layer contains 2.0%-3.2% epoxy reactive groups.

[0014] Based on coatings, this invention also proposes a method for preparing a high-end coating for metal printing inks based on polyvinyl chloride resin, comprising the following steps: S1. Remove impurities from 28-42 parts of the core-shell PVC matrix through a 100-mesh grading sieve, put it into a continuous reactor, add 75%-85% of the total mass of the reaction solvent, control the temperature inside the reactor at 55-65℃ and the stirring speed at 300-400r / min, stir at a constant temperature and dissolve until the light transmittance of the solution is ≥99.5%, and obtain the resin base material. The double-shell metal powder is activated by plasma for 10-15 minutes, then pre-coated with 40%-50% of the total mass of anchoring agent, and vacuum dried at 80-90℃ and vacuum degree -0.09MPa until the moisture content is ≤0.3% to obtain the pre-treated effect pigment. The liquid rheology modifier and the remaining anchoring agent are stored in a sealed container at a constant temperature of 23±3℃, and gently stirred for 10 seconds every 4 hours to avoid separation. S2. Add the pretreated effect pigments and cage-type additives to the high-speed dispersion kettle, and add 30%-40% of the total mass of the resin base. Disperse in three stages, controlling the temperature inside the dispersion kettle to ≤35℃ throughout the process. Pre-dispersion: Stir at 800-1000 r / min for 6 min at medium speed to achieve initial wetting of pigments and additives, with a wetting rate ≥99%; Grinding and dispersion: A horizontal sand mill is used for circulating grinding for 12-18 minutes. The grinding media is zirconium beads with a particle size of 0.6-0.8 mm and a zirconium bead filling rate of 60%-70%. The grinding speed is 2800-3200 r / min, and the grinding temperature is controlled below 40℃. The output fineness is ≤3μm, and the particle size distribution uniformity is ≥98%. Homogenization and stabilization: Stir at low speed for 4 minutes at a speed of 400-500 r / min, slowly add the remaining resin base material while stirring to eliminate shear stress in the system, achieve a mixing uniformity of ≥99.5%, and ensure that the system has no obvious particles or stratification. S3. Pump the rheology modifier and the remaining part of the reaction solvent into the static mixer in proportion, control the medium temperature of the static mixer at 20-25℃, the mixing speed at 1500-2000 r / min, premix into a homogeneous solution, and inject it into the dispersion vessel in a pulse manner at a pulse frequency of 10-15 times / min and an injection rate of 5-8 mL / min to avoid system flocculation caused by excessively high local concentrations; S4. Mix and control the injected system in two stages, monitoring viscosity online throughout the process and adjusting stirring parameters in real time: Initial adjustment: Stir at low speed for 3 minutes at 300-350 rpm, and control the initial system viscosity at 80-120 s / 25℃ using a Fork 4 cup, with a viscosity deviation ≤5%. Fine-tuning: Stir at 500-600 r / min for 5 min at medium speed. Adjust the stirring speed according to the online viscosity feedback. The final system viscosity is controlled at 140-180 s / 25℃ in the Forbes 4 cup. The system thixotropic value is ≥3.5. After standing for 24 h, there is no sedimentation or stratification. S5. Filter the prepared coating through a 1μm bag filter at a pressure of 0.1-0.15MPa and a filtration rate of 10-15L / h. Then, it undergoes vacuum degassing treatment with a vacuum degree of -0.085 to -0.095 MPa, a degassing temperature of 30-35℃, a degassing time of 15-25 min, and the bubble content of the system is controlled to be ≤0.05%, and the diameter of a single bubble is ≤50μm; S6. The deaerated coating is cured at a constant temperature of 23±2℃, with a curing humidity of 45%-55% and a curing time of 24-36 hours. During the curing process, the coating is stirred at a low speed of 200r / min for 1 minute every 8 hours. After completion, it is filtered twice with a filtration accuracy of 0.8μm. The light transmittance of the filtered coating is ≥98%. S7. The high-end coating for metal printing ink based on polyvinyl chloride resin prepared in steps S1 to S6 is subjected to performance testing and sealed and packaged. After passing the inspection, the product is sealed in a light-proof container and filled with nitrogen gas with a purity of ≥99.99% to prevent the coating from oxidizing and deteriorating.

[0015] Preferably, the performance testing in step S7 includes adhesion testing, flexural strength testing, specular gloss testing, salt spray resistance testing, chemical resistance testing, and VOC content testing of the coating after curing. Adhesion testing was performed using the cross-cut test method, with a cross-cut spacing of 1 mm, and the adhesion grade was ≤1. The bending resistance test was conducted using a bending tester with a bending angle of 180° and a bending radius of 1mm. No cracking or ink fading was observed. Specular gloss was measured at a 60° angle, with a gloss level ≥ 85 GU. Salt spray resistance was tested using a neutral salt spray test for 72 hours. The coating showed no rust or peeling. VOC content ≤10g / L.

[0016] Compared with the prior art, the beneficial effects of the present invention are: This invention relates to a high-end coating for metal printing inks based on polyvinyl chloride (PVC) resin. Through molecular structure design and synergistic modification of components, it utilizes a core-shell structure PVC film-forming matrix to simultaneously achieve coating rigidity and flexibility. By employing a double-shell structure metallic effect pigment, it achieves multiple effects including barrier against discoloration, matrix compatibility to prevent sedimentation, and interfacial anchoring to enhance adhesion, significantly improving mirror gloss and storage stability. The use of single-molecule multifunctional cage-type additives avoids the compatibility defects of multi-additive formulations, simultaneously achieving synergistic effects of light stability, thermal stability, leveling, and anchoring. Furthermore, it utilizes a gradient volatilization reaction... This solvent system balances printability and environmental friendliness, achieving near-zero VOC emissions. Reactive components participate in film formation, enhancing coating crosslinking density and chemical resistance. Coupled with a phased, precisely controlled preparation process, it achieves closed-loop management of the entire process, including pigment wetting, dispersion, grinding, and rheological regulation, significantly improving batch stability. The coating's mixing uniformity is ≥99.5%, making it suitable for high-speed, high-precision metal printing processes. The coating also possesses excellent adhesion, flexural strength, weather resistance, and salt spray resistance, making it widely applicable in various scenarios such as food-contact metal packaging and high-end home appliance panels. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0018] I. Materials: Unless otherwise stated, all materials used in this invention are commercially available.

[0019] This invention proposes a high-end coating for metal printing ink based on polyvinyl chloride resin, which is composed of the following raw materials in parts by weight: core-shell PVC matrix: 28-42 parts; double-shell metal powder: 12-28 parts; cage-type additive: 8-16 parts; reaction solvent: 22-38 parts; rheology modifier: 1.2-3.5 parts; anchoring additive: 2.5-6 parts.

[0020] It should be noted that the core-shell PVC matrix consists of a core layer and a shell layer. The core layer is composed of highly cross-linked vinyl chloride-divinylbenzene copolymer microspheres, and the shell layer is composed of low-cross-linked gradient functionalized vinyl chloride-monobutyl maleate-glycidyl methacrylate terpolymer segments. The core layer has a weight ratio of 16-24 parts, and the shell layer has a weight ratio of 12-18 parts. The number-average molecular weight of the core layer is 80,000-120,000, and the degree of cross-linking is 12%-18%, with in-situ embedded hindered phenolic anti-aging groups. The number-average molecular weight of the shell layer is 20,000-35,000. From the core to the shell, the phosphate anchoring groups, epoxy reactive groups, and hydroxyl compatible groups are distributed in a gradient increasing manner, with a grafting rate of 25%-35%.

[0021] It should be noted that the double-shell metal powder consists of a core, an inner shell, and an outer shell. The core is composed of plasma-activated floating aluminum-silver powder and silane-modified copper-zinc alloy powder. The inner shell is a dense nano-silica layer prepared by atomic layer deposition. The outer shell is a polydopamine-mediated polyvinyl chloride segment grafted bifunctional layer. The floating aluminum-silver powder in the core is 9-18 parts by weight, and the silane-modified copper-zinc alloy powder is 3-10 parts by weight. The inner shell is 50-80 nm thick and has no pinholes. The outer shell is 100-150 nm thick and has pH-responsive carboxyl groups on its surface. The surface hydroxyl content of the core after plasma activation is ≥8%.

[0022] It should be noted that the cage-type additive uses octavinyl cage-type silsesquioxane as the core, with vinyl chloride-acrylate copolymer segments grafted at the apex, and hindered amine light-stabilizing groups, epoxy heat-stabilizing groups, and phosphate ester anchoring groups grafted at the remaining apex; the weight percentage of octavinyl cage-type silsesquioxane is 30%-45%, the weight percentage of vinyl chloride-acrylate copolymer segments is 35%-50%, and the total weight percentage of functional groups is 10%-25%; the number average molecular weight of the cage-type additive is 15,000-25,000, and its compatibility with the core-shell PVC matrix is ​​≥99.5%.

[0023] It should be noted that the reaction solvent is a mixture of a non-reactive gradient volatile solvent and a reactive solvent in a mass ratio of 4:6-5:5; the non-reactive gradient volatile solvent is a mixture of dimethyl carbonate, propylene glycol methyl ether acetate, and high-boiling-point environmentally friendly solvent D40 in a weight ratio of 6-12:8-14:5-8, with boiling points of 90℃, 145℃, and 200-220℃ respectively; the reactive solvent is a mixture of glyceryl carbonate methacrylate and vinyl ethylene carbonate in a weight ratio of 3:2-2:3. Both glyceryl carbonate methacrylate and vinyl ethylene carbonate can undergo free radical copolymerization with the core-shell PVC matrix.

[0024] It should be noted that the rheology modifier is a compound of polyether-modified polysiloxane leveling agent, acrylate defoamer, hydrogenated castor oil thixotropic agent, and fluorinated mica antiflocculation agent in a weight ratio of 0.4-1.2:0.3-0.8:0.5-1.5:0.2-0.6; the fluorinated mica antiflocculation agent has a particle size of 0.5-1μm and a volume resistivity ≥10¹²Ω·cm.

[0025] It should be noted that the anchoring agent is a compound of phosphate-modified vinyl chloride resin and titanate coupling agent in a weight ratio of 1.5-3.5:1-2.5; the phosphate-modified vinyl chloride resin is a terpolymer of vinyl chloride-vinyl acetate-diphenyl phosphate, with a phosphate group content of 3.5%-5.5% and a number average molecular weight of 30,000-45,000; the titanate coupling agent is isopropyltris(stearoyl) titanate.

[0026] It should be noted that the preparation method of the core-shell PVC matrix is ​​as follows: vinyl chloride, divinylbenzene, and hindered phenol monomers are added to a reactor and polymerized at 65-75℃ and 0.3-0.5MPa for 2-3 hours to obtain core layer microspheres; monobutyl maleate, glycidyl methacrylate, and an initiator are added to the reactor, the temperature is raised to 80-85℃, and polymerization continues for 1.5-2 hours, controlling the grafting rate of the shell layer. After cooling, the microspheres are pulverized and sieved to obtain the core-shell PVC matrix; the content of hindered phenol anti-aging groups in the core layer is 0.8%-1.5%, and the content of epoxy reactive groups in the shell layer is 2.0%-3.2%.

[0027] Unless otherwise stated, all components of the formulation of this invention are commercially available industrial-grade qualified products that meet the relevant standards for raw materials used in metal printing inks.

[0028] II. Process: Based on the above formulation, this invention also proposes a method for preparing a high-end coating for metal printing ink based on polyvinyl chloride resin, specifically including the following steps: S1. Remove impurities from 28-42 parts of the core-shell PVC matrix through a 100-mesh sieve, add it to a continuous reactor, add 75%-85% of the total mass of the reaction solvent, control the reactor temperature at 55-65℃ and the stirring speed at 300-400 r / min, and stir at a constant temperature until the solution transmittance is ≥99.5% to obtain the resin base material; Activate the double-shell metal powder with plasma for 10-15 min, then pre-coat it with 40%-50% of the total mass of the anchoring agent, and vacuum dry it at 80-90℃ and a vacuum degree of -0.09MPa until the moisture content is ≤0.3% to obtain the pretreated effect pigment; Store the liquid additives, rheology modifiers and the remaining anchoring agent at a constant temperature of 23±3℃ in a sealed container, and stir gently for 10 seconds every 4 hours to avoid separation; S2. Add the pretreated effect pigments and cage-type additives to the high-speed dispersion kettle, and add 30%-40% of the total mass of the resin base. Disperse in three stages, controlling the temperature inside the dispersion kettle to ≤35℃ throughout the process. Pre-dispersion: Stir at 800-1000 r / min for 6 min at medium speed to achieve initial wetting of pigments and additives, with a wetting rate ≥99%; Grinding and dispersion: A horizontal sand mill is used for circulating grinding for 12-18 minutes. The grinding media is zirconium beads with a particle size of 0.6-0.8 mm and a zirconium bead filling rate of 60%-70%. The grinding speed is 2800-3200 r / min, and the grinding temperature is controlled below 40℃. The output fineness is ≤3μm, and the particle size distribution uniformity is ≥98%. Homogenization and stabilization: Stir at low speed for 4 minutes at a speed of 400-500 r / min, slowly add the remaining resin base material while stirring to eliminate shear stress in the system, achieve a mixing uniformity of ≥99.5%, and ensure that the system has no obvious particles or stratification. S3. Pump the rheology modifier and the remaining part of the reaction solvent into the static mixer in proportion, control the medium temperature of the static mixer at 20-25℃, the mixing speed at 1500-2000 r / min, premix into a homogeneous solution, and inject it into the dispersion vessel in a pulse manner at a pulse frequency of 10-15 times / min and an injection rate of 5-8 mL / min to avoid system flocculation caused by excessively high local concentrations; S4. Mix and control the injected system in two stages, monitoring viscosity online throughout the process and adjusting stirring parameters in real time: Initial adjustment: Stir at low speed for 3 minutes at 300-350 rpm, and control the initial system viscosity at 80-120 s / 25℃ using a Fork 4 cup, with a viscosity deviation ≤5%. Fine-tuning: Stir at 500-600 r / min for 5 min at medium speed. Adjust the stirring speed according to the online viscosity feedback. The final system viscosity is controlled at 140-180 s / 25℃ in the Forbes 4 cup. The system thixotropic value is ≥3.5. After standing for 24 h, there is no sedimentation or stratification. S5. Filter the prepared coating through a 1μm bag filter at a pressure of 0.1-0.15MPa and a filtration rate of 10-15L / h; then perform vacuum degassing treatment at a vacuum degree of -0.085 to -0.095MPa, a degassing temperature of 30-35℃, and a degassing time of 15-25min, controlling the bubble content of the system to be ≤0.05% and the diameter of a single bubble to be ≤50μm; S6. The deaerated coating is cured at a constant temperature of 23±2℃, with a curing humidity of 45%-55% and a curing time of 24-36 hours. During the curing process, the coating is stirred at a low speed of 200r / min for 1 minute every 8 hours. After completion, it is filtered twice with a filtration accuracy of 0.8μm. The light transmittance of the filtered coating is ≥98%. S7. The high-end coatings for metal printing inks based on polyvinyl chloride resin prepared in steps S1 to S6 are subjected to performance testing and sealed packaging; after passing the test, they are sealed in light-proof packaging, and the packaging container is filled with nitrogen gas for protection, with nitrogen purity ≥99.99%, to avoid oxidation and deterioration of the coating.

[0029] It should be noted that the performance testing in step S7 includes adhesion testing, flexural strength testing, specular gloss testing, salt spray resistance testing, chemical resistance testing, and VOC content testing of the coating after curing. Adhesion testing uses the cross-cut test with a 1mm grid spacing and an adhesion grade ≤1. Flexural strength testing uses a bending tester with a 180° bending angle and a 1mm bending radius, showing no cracking or ink fading. Specular gloss testing is performed at a 60° angle, with a gloss level ≥85GU. Salt spray resistance testing uses a neutral salt spray test with a 72-hour spray time, showing no rust or peeling of the coating. VOC content is ≤10g / L.

[0030] Example 1: In this example, a high-end coating for metal printing ink based on polyvinyl chloride resin is prepared according to the following process. The formulation components include: Core-shell PVC matrix: 35 parts, of which 20 parts are core layer and 15 parts are shell layer; Double-shell metal powder: 20 parts, including 14 parts of floating aluminum silver powder and 6 parts of silane-modified copper-zinc alloy powder; Cage-type additive: 12 parts; Reaction solvent: 30 parts, of which 13.5 parts are non-reactive gradient volatile solvents and 16.5 parts are reactive solvents, with a mass ratio of 4.5:5.5; Rheology modifier: 2.2 parts; Anchoring aid: 4 parts; Includes the following steps: Step 1: Raw material pretreatment and metering: 35 parts of core-shell PVC matrix were removed from impurities by a 100-mesh grading sieve and put into a continuous reactor. 80% of the total mass of the reaction solvent was added. The temperature inside the reactor was controlled at 60℃ and the stirring speed was 350r / min. The mixture was stirred at a constant temperature until the light transmittance of the solution was 99.7%, and the resin matrix was obtained. Twenty parts of double-shell metal powder were plasma activated for 12 minutes, then pre-coated with 45% of the total mass of anchoring agent, and vacuum dried at 85℃ and vacuum degree -0.09MPa to a moisture content of 0.2% to obtain a pre-treated effect pigment. 2.2 parts of liquid rheology modifier and the remaining anchoring modifier are stored in a sealed container at a constant temperature of 23±3℃, and gently stirred for 10 seconds every 4 hours to avoid separation. Step 2: Staged dispersion preparation: Pre-dispersion: Add 12 parts of pretreated effect pigment and cage-type additive to a high-speed dispersion kettle, add 35% of the total mass of resin base, stir at 900 r / min for 6 min at medium speed, and the pigment wetting rate is 99.5%; Grinding and dispersion: A horizontal sand mill was used for circulating grinding for 15 minutes. The grinding media was zirconium beads with a particle size of 0.7 mm and a zirconium bead filling rate of 65%. The grinding speed was 3000 r / min, and the grinding temperature was controlled below 35℃. The output fineness was 2 μm, and the particle size distribution uniformity was 98.8%. Homogenization and stabilization: Stir at low speed for 4 minutes at 450 r / min, slowly add the remaining resin base material while stirring to eliminate shear stress in the system, achieve a mixing uniformity of 99.7%, and ensure that the system has no obvious particles or stratification. The temperature inside the dispersion vessel is controlled to be ≤35℃ throughout the process. Step 3: Rheology modifier premixing and injection: 2.2 parts of rheology modifier and the remaining part of reaction solvent were pumped into a static mixer in proportion. The temperature of the medium in the static mixer was controlled at 22℃ and the mixing speed was 1800 r / min. The mixture was premixed into a homogeneous solution and injected into the dispersion vessel in a pulsed manner at a pulse frequency of 12 times / min and an injection rate of 6.5 mL / min. Step 4: System mixing and rheological control: Initial adjustment: Stir at 320 rpm for 3 minutes, controlling the initial system viscosity at 100 s / 25℃ (Ford Cup 4), with a viscosity deviation of 3%. Fine-tuning: Stir at 550 r / min for 5 min at medium speed. Adjust the stirring speed according to the online viscosity feedback. The final system viscosity is controlled at 160 s / 25℃ in the Forbes 4 cup. The system thixotropic value is 4.2. After standing for 24 h, there is no sedimentation or stratification. Step 5: Filtration and Vacuum Degassing: The prepared coating was filtered through a 1μm bag filter at a pressure of 0.12MPa and a filtration rate of 12L / h; then it was subjected to vacuum degassing treatment at a vacuum degree of -0.09MPa, a degassing temperature of 32℃, and a degassing time of 20min. The bubble content of the system was 0.03%, and the diameter of a single bubble was ≤40μm. Step 6: Constant temperature curing and secondary filtration: The deaerated coating was subjected to constant temperature curing at 23±2℃ and 50% humidity for 30 hours. During curing, the coating was stirred at a low speed of 200r / min for 1 minute every 8 hours. After curing, the coating was filtered twice with a filtration accuracy of 0.8μm. The light transmittance of the filtered coating was 98.6%. Step 7: Performance Testing and Packaging The prepared coating was subjected to performance testing. After passing the test, it was sealed in a light-proof container and filled with nitrogen gas with a purity of 99.99%.

[0031] Example 2: In this example, the core-shell PVC matrix consists of 28 parts, the double-shell metal powder consists of 12 parts, the cage-type additive consists of 8 parts, the reaction solvent consists of 22 parts, the rheology modifier consists of 1.2 parts, and the anchoring additive consists of 2.5 parts; the core-shell PVC matrix consists of 16 parts core layer and 12 parts shell layer; the double-shell metal powder consists of 9 parts floating aluminum silver powder and 3 parts silane-modified copper-zinc alloy powder; the reaction solvent consists of a non-reactive gradient volatile solvent to a reactive solvent in a mass ratio of 4:6; other process parameters are the same as in Example 1.

[0032] Example 3: In this example, the core-shell PVC matrix consists of 42 parts, the double-shell metal powder consists of 28 parts, the cage-type additive consists of 16 parts, the reaction solvent consists of 38 parts, the rheology modifier consists of 3.5 parts, and the anchoring additive consists of 6 parts; the core layer of the core-shell PVC matrix consists of 24 parts and the shell layer consists of 18 parts; the double-shell metal powder consists of 18 parts of floating aluminum silver powder and 10 parts of silane-modified copper-zinc alloy powder; the mass ratio of non-reactive gradient volatile solvent to reactive solvent in the reaction solvent is 5:5; other process parameters are the same as in Example 1.

[0033] The components of the coating formulation prepared in the examples are shown in Table 1: Table 1. Components of the coating formulation prepared in the examples

[0034] Comparative Example 1: In this comparative example, the core-shell PVC matrix was 50 parts, and the other formulation components and process parameters were the same as in Example 1.

[0035] Comparative Example 2: In this comparative example, the amount of bishell metal powder was 8 parts, and the other formulation components and process parameters were the same as in Example 1.

[0036] Comparative Example 3: In this comparative example, the reaction solvent was 15 parts, and the other formulation components and process parameters were the same as in Example 1.

[0037] The components of the coating formulations prepared in the comparative proportions are shown in Table 2: Table 2. Component list of coating formulations prepared in the comparative examples.

[0038] III. Performance Testing: The following performance tests were performed on the high-end coatings for metal printing inks based on polyvinyl chloride resin prepared in the examples and comparative examples: a. Adhesion test: According to GB / T13217.7-2009 "Test Methods for Liquid Inks - Adhesion Test", the cross-cut test is adopted with a cross-cut spacing of 1mm. Grade 0 is the best, and the higher the grade, the worse the adhesion. b. Bending resistance test: According to GB / T1731-2020 "Determination of flexibility of paint and varnish film", a bending tester is used with a bending angle of 180° and a bending radius of 1mm to observe whether the coating cracks or loses ink. c. Specular gloss test: According to GB / T9754-2007 "Determination of specular gloss of paint film without metallic pigments at 20°, 60° and 85°", the specular gloss of the coating at 60° angle is tested, and the unit is GU. d. Salt spray resistance test: According to GB / T1771-2007 "Determination of resistance to neutral salt spray of paints and varnishes", a neutral salt spray test was conducted for 72 hours, and the coating was observed to see if rust or peeling occurred. e. VOC content testing: According to GB / T23984-2009 "Determination of volatile organic compounds (VOC in can) in low-VOC latex paints and varnishes", the VOC content in the paint can is tested, in g / L; f. Storage stability test: According to GB / T6753.3-1986 "Test method for storage stability of coatings", the coatings are sealed and stored at 25℃. Observe whether sedimentation, stratification, or clumping occurs, and record the stable storage time in months.

[0039] Performance data for the examples and comparative examples are shown in Table 3: Table 3 Performance data for examples and comparative examples

[0040] IV. Analysis Conclusion: As shown in Tables 2 and 3, in Comparative Example 1, the excessive amount of core-shell PVC matrix led to an excessively high solid content in the system, resulting in increased brittleness after film formation, decreased bending resistance, a drop in adhesion grade to level 2, VOC content exceeding the standard limit, and a 50% decrease in storage stability. In Comparative Example 2, the insufficient double-shell metal powder led to a significant decrease in the metallic gloss of the coating, localized corrosion in the 72-hour salt spray test, and a decrease in protective performance. In Comparative Example 3, the insufficient reaction solvent led to excessively high system viscosity, uneven pigment dispersion, severely reduced printability, and a significant decrease in coating adhesion, bending resistance, and salt spray resistance, with a storage stability of only 6 months. This verifies the scientific validity and rationality of the component range of the coating formulation of this invention.

[0041] According to Tables 1 and 3, the formulation of Example 1 of this invention is well-balanced. The 35 parts of the core-shell PVC matrix balance the rigidity and flexibility of the coating, while the 20 parts of the double-shell metal powder ensure metallic luster and protective performance. Combined with the multifunctional synergy of the cage-type additives and the environmentally friendly compatibility of the reaction solvent, all performances are optimal. The adhesion is grade 0, there is no cracking or ink fading after 180° bending, the gloss is 92 GU at 60°, there are no abnormalities after 72 hours of salt spray, the VOC content is 8 g / L, and the storage stability reaches 24 months. Examples 2 and 3 are within the lower and upper limits of the formulation range, respectively, and all performances meet the technical requirements, verifying the wide-window adaptability and process stability of the formulation system of this invention.

[0042] In summary, Example 1 is the preferred embodiment of the present invention.

[0043] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0044] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A high-end coating for metal printing ink based on polyvinyl chloride resin, characterized in that, It is composed of the following raw materials in parts by weight: core-shell PVC matrix: 28-42 parts; double-shell metal powder: 12-28 parts; cage-type additives: 8-16 parts; reaction solvent: 22-38 parts; rheology modifiers: 1.2-3.5 parts; anchoring additives: 2.5-6 parts.

2. The high-end coating for metal printing ink based on polyvinyl chloride resin according to claim 1, characterized in that, The core-shell PVC matrix is ​​composed of a core layer and a shell layer. The core layer is a highly cross-linked vinyl chloride-divinylbenzene copolymer microsphere, and the shell layer is a low-cross-linked gradient functionalized vinyl chloride-monobutyl maleate-glycidyl methacrylate terpolymer segment. The core layer has a weight of 16-24 parts, and the shell layer has a weight of 12-18 parts.

3. The high-end coating for metal printing ink based on polyvinyl chloride resin according to claim 2, characterized in that, The double-shell metal powder consists of a core, an inner shell, and an outer shell. The core is a floating aluminum-silver powder and a silane-modified copper-zinc alloy powder that have been activated by plasma surface treatment. The inner shell is a dense nano-silica layer prepared by atomic layer deposition. The outer shell is a polydopamine-mediated polyvinyl chloride segment grafted bifunctional layer. The core contains 9-18 parts by weight of floating aluminum silver powder and 3-10 parts by weight of silane-modified copper-zinc alloy powder; the inner shell has a thickness of 50-80 nm; and the outer shell has a thickness of 100-150 nm.

4. The high-end coating for metal printing ink based on polyvinyl chloride resin according to claim 1, characterized in that, The cage-type additive has an octavinyl cage-type silsesquioxane as its core, with vinyl chloride-acrylate copolymer segments grafted at the apex, and hindered amine light-stabilizing groups, epoxy heat-stabilizing groups, and phosphate anchoring groups grafted at the remaining apex. The octavinyl cage-like silsesquioxane accounts for 30%-45% by weight, the vinyl chloride-acrylate copolymer segment accounts for 35%-50% by weight, and the total weight of functional groups accounts for 10%-25%.

5. A high-end coating for metal printing ink based on polyvinyl chloride resin according to claim 4, characterized in that, The reaction solvent is a mixture of a non-reactive gradient volatile solvent and a reactive solvent in a mass ratio of 4:6-5:5; The non-reactive gradient volatile solvent is composed of dimethyl carbonate, propylene glycol methyl ether acetate, and high-boiling-point environmentally friendly solvent D40 in a weight ratio of 6-12:8-14:5-8, with boiling points of 90℃, 145℃, and 200-220℃ respectively. The reactive solvent is a mixture of glyceryl methacrylate and vinyl ethylene carbonate in a weight ratio of 3:2 to 2:

3.

6. A high-end coating for metal printing ink based on polyvinyl chloride resin according to claim 4, characterized in that, The rheology modifier is a compound of polyether-modified polysiloxane leveling agent, acrylate defoamer, hydrogenated castor oil thixotropic agent and fluorinated mica antiflocculation agent in a weight ratio of 0.4-1.2:0.3-0.8:0.5-1.5:0.2-0.

6. The fluorinated mica antiflocculation agent has a particle size of 0.5-1μm and a volume resistivity of ≥10¹²Ω·cm.

7. A high-end coating for metal printing ink based on polyvinyl chloride resin according to claim 1, characterized in that, The anchoring aid is a compound of phosphate-modified chloroacetic acid resin and titanate coupling agent in a weight ratio of 1.5-3.5:1-2.5; The phosphate-modified vinyl chloride resin is a terpolymer of vinyl chloride-vinyl acetate-diphenyl phosphate, with a phosphate group content of 3.5%-5.5% and a number average molecular weight of 30,000-45,000.

8. A high-end coating for metal printing ink based on polyvinyl chloride resin according to claim 1, characterized in that, The preparation method of the core-shell PVC matrix is ​​as follows: vinyl chloride, divinylbenzene and hindered phenol monomer are put into a reaction vessel and polymerized at 65-75℃ and 0.3-0.5MPa for 2-3 hours to obtain core layer microspheres; Add monobutyl maleate, glycidyl methacrylate, and initiator to the reactor, heat to 80-85℃, continue polymerization for 1.5-2 hours, control the shell grafting rate, cool, crush and sieve to obtain core-shell PVC matrix; The core layer contains 0.8%-1.5% hindered phenolic anti-aging groups, and the shell layer contains 2.0%-3.2% epoxy reactive groups.

9. A method for preparing a high-end coating for metal printing ink based on polyvinyl chloride resin according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Remove impurities from 28-42 parts of the core-shell PVC matrix through a 100-mesh grading sieve, put it into a continuous reactor, add 75%-85% of the total mass of the reaction solvent, control the temperature inside the reactor at 55-65℃ and the stirring speed at 300-400r / min, stir at a constant temperature and dissolve until the light transmittance of the solution is ≥99.5%, and obtain the resin base material. The double-shell metal powder is activated by plasma for 10-15 minutes, then pre-coated with 40%-50% of the total mass of anchoring agent, and vacuum dried at 80-90℃ and vacuum degree -0.09MPa until the moisture content is ≤0.3% to obtain the pre-treated effect pigment. The liquid rheology modifier and the remaining anchoring agent are stored in a sealed container at a constant temperature of 23±3℃, and gently stirred for 10 seconds every 4 hours to avoid separation. S2. Add the pretreated effect pigments and cage-type additives to the high-speed dispersion kettle, and add 30%-40% of the total mass of the resin base. Disperse in three stages, controlling the temperature inside the dispersion kettle to ≤35℃ throughout the process. Pre-dispersion: Stir at 800-1000 r / min for 6 min at medium speed to achieve initial wetting of pigments and additives, with a wetting rate ≥99%; Grinding and dispersion: A horizontal sand mill is used for circulating grinding for 12-18 minutes. The grinding media is zirconium beads with a particle size of 0.6-0.8 mm and a zirconium bead filling rate of 60%-70%. The grinding speed is 2800-3200 r / min, and the grinding temperature is controlled below 40℃. The output fineness is ≤3μm, and the particle size distribution uniformity is ≥98%. Homogenization and stabilization: Stir at low speed for 4 minutes at a speed of 400-500 r / min, slowly add the remaining resin base material while stirring to eliminate shear stress in the system, achieve a mixing uniformity of ≥99.5%, and ensure that the system has no obvious particles or stratification. S3. Pump the rheology modifier and the remaining part of the reaction solvent into the static mixer in proportion, control the medium temperature of the static mixer at 20-25℃, the mixing speed at 1500-2000 r / min, premix into a homogeneous solution, and inject it into the dispersion vessel in a pulse manner at a pulse frequency of 10-15 times / min and an injection rate of 5-8 mL / min to avoid system flocculation caused by excessively high local concentrations; S4. Mix and control the injected system in two stages, monitoring viscosity online throughout the process and adjusting stirring parameters in real time: Initial adjustment: Stir at low speed for 3 minutes at 300-350 rpm, and control the initial system viscosity at 80-120 s / 25℃ using a Fork 4 cup, with a viscosity deviation ≤5%. Fine-tuning: Stir at 500-600 r / min for 5 min at medium speed. Adjust the stirring speed according to the online viscosity feedback. The final system viscosity is controlled at 140-180 s / 25℃ in the Forbes 4 cup. The system thixotropic value is ≥3.

5. After standing for 24 h, there is no sedimentation or stratification. S5. Filter the prepared coating through a 1μm bag filter at a pressure of 0.1-0.15MPa and a filtration rate of 10-15L / h. Then, it undergoes vacuum degassing treatment with a vacuum degree of -0.085 to -0.095 MPa, a degassing temperature of 30-35℃, a degassing time of 15-25 min, and the bubble content of the system is controlled to be ≤0.05%, and the diameter of a single bubble is ≤50μm; S6. The deaerated coating is cured at a constant temperature of 23±2℃, with a curing humidity of 45%-55% and a curing time of 24-36 hours. During the curing process, the coating is stirred at a low speed of 200r / min for 1 minute every 8 hours. After completion, it is filtered twice with a filtration accuracy of 0.8μm. The light transmittance of the filtered coating is ≥98%. S7. Perform performance testing on the high-end coatings for metal printing inks based on polyvinyl chloride resin prepared in steps S1 to S6 and then seal and package them.

10. A method for preparing a high-end coating for metal printing ink based on polyvinyl chloride resin according to claim 9, characterized in that, The performance testing in step S7 includes adhesion testing, flexural strength testing, specular gloss testing, salt spray resistance testing, chemical resistance testing, and VOC content testing of the coating after curing.

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