A pigment ink for aluminum plate and a method for preparing the same, and a method for printing a pattern on an aluminum plate

Abstract

The application provides a pigment ink for aluminum plate and a preparation method thereof, and a printing method for patterns on the aluminum plate. The ink comprises a pigment dispersion color paste and a resin. The pigment dispersion color paste comprises inorganic pigments, and the resin is an epoxy resin. The molecular weight of the epoxy resin is 800-2000, and the shrinkage rate of the epoxy resin is 0.5%-1.2%. The mass ratio of the pigment dispersion color paste to the epoxy resin is (1.5-2.0):1 in percentage by mass. The epoxy resin forms a covalent bond with the aluminum plate under heating conditions, and the problem of poor adhesion of the pigment on the aluminum plate is solved. On the basis of enhancing the adhesion, the selected pigment is inorganic pigment, and the inorganic pigment has strong acid resistance and weather resistance. The ratio between the color paste and the resin is controlled, the hardness is maintained, the toughness is ensured, the cracking during impact is avoided, and the impact strength of the composite material is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of digital inkjet, in particular to a pigment ink for aluminum plate, a preparation method thereof and a printing method of patterns on aluminum plate. BACKGROUND

[0002] Aluminum plate has the advantages of light weight, high strength, corrosion resistance, easy processing, good electrical and thermal conductivity, easy processing and convenient and fast construction, and high recycling value, and is widely used in the construction industry, packaging industry, transportation, electronic circuits and mechanical equipment industries, such as building curtain walls, interior decoration, door and window frames, beverage cans and food packaging materials.

[0003] With the development of society, people have higher and higher requirements for the appearance of decorations. Therefore, the current way to transform aluminum plate is to print on its surface. One of the main printing methods is anodic oxidation, which forms an oxide film on the metal surface through electrolysis. The dye molecules are attached to the surface of the aluminum plate through physical and chemical adsorption of the oxide film, but the color tone is not bright. Another way is UV inkjet printing or water-based ink printing, but most of the pigments used are organic pigments. However, organic pigments have relatively poor light resistance, acid resistance and alkali resistance, and these methods cannot meet the application requirements of aluminum plate. In addition, the surface of the aluminum plate is smooth, and the organic pigment particles are difficult to adhere to the surface of the aluminum plate, and the ink layer is easy to fall off. SUMMARY

[0004] The first object of the present application is to provide a pigment ink for aluminum plate, which solves the problems of weak adhesion, dull color, poor light resistance, acid resistance and alkali resistance of the existing pigment ink for aluminum plate.

[0005] The second object of the present application is to provide a preparation method of a pigment ink for aluminum plate, which is used to prepare the above-mentioned pigment ink for aluminum plate.

[0006] The third object of the present application is to provide a printing method of patterns on aluminum plate, which uses the above-mentioned pigment ink for aluminum plate.

[0007] To achieve the first object of the present application, a pigment ink for aluminum plate comprises a pigment dispersion color paste and a resin, the pigment dispersion color paste comprises inorganic pigments, and the resin is an epoxy resin with a molecular weight of 800 to 2000 and a shrinkage rate of 0.5% to 1.2%. The mass ratio of the pigment dispersion color paste to the epoxy resin is (1.5-2.0):1 by mass percentage.

[0008] It can be seen from the above scheme that epoxy resin has excellent bonding strength to both metals and non-metals under the action of van der Waals force and hydrogen bond. Not only that, during the heating and curing process, the active groups of epoxy resin can also cross-link with the surface of the aluminum plate to form chemical bonds. When the epoxy resin is cured, the pigment is wrapped in it, thereby improving the adhesion of the pigment to the aluminum plate and forming a hard protective layer to improve the abrasion resistance. The relative molecular weight of the epoxy resin is controlled between 800 and 2000, which has more cross-linking points, and the number of hydroxyl and epoxy groups is relatively more. The connectivity with the aluminum plate is stronger, meeting the adhesion requirements while avoiding the problem of excessive molecular weight leading to excessive steric hindrance, excessive ink viscosity leading to nozzle clogging, hard resin film, and easy cracking; it also prevents the molecular weight from being too small, the interaction force between the epoxy resin and the aluminum surface is small, and the adhesion of the pigment cannot be improved well. The shrinkage rate of the epoxy resin is controlled between 0.5% and 1.2%. The volume shrinkage rate is small during the curing process, and the internal stress generated is correspondingly reduced, avoiding internal stress.

[0009] Excessive shrinkage can cause cracking in the epoxy film, while lower shrinkage epoxy resins significantly increase ink preparation costs. Therefore, controlling the shrinkage of the epoxy resin within a range of 0.5% to 1.2% can effectively control costs while avoiding cracking in the epoxy film. Limiting the mass ratio of pigment dispersion paste to epoxy resin to 1.5-2.0:1 offsets the inherent brittleness, poor toughness, and impact resistance of epoxy resin. By adding pigment particles and uniformly dispersing them throughout the epoxy resin, silver streaks form between the particles and the matrix when the material is impacted, absorbing some of the deformation work. The matrix between the particles also undergoes plastic deformation, absorbing some of the impact energy. As the silver streaks propagate through the resin, they are hindered and inactivated by the particles, ultimately stopping them, preventing destructive cracking and achieving a toughening effect. By limiting the ratio of pigment dispersion paste to epoxy resin, a certain degree of toughness is achieved while maintaining hardness, preventing cracking during impact and improving the impact strength of the composite material.

[0010] A further solution is that the pigment ink for aluminum plate further includes an ink dispersant, the ink dispersant includes a first dispersant and a second dispersant, the first dispersant is at least one of polyacrylate ammonium salt, polyacrylate sodium salt, and modified polyurethane; the adsorption heat of the first dispersant is 20 kJ·mol -1 to 30 kJ·mol -1 The second dispersant has an adsorption heat of 50 kJ·mol -1 to 100 kJ·mol -1 of oleic acid.

[0011] Further, the pigment dispersion color paste further comprises a color paste dispersant, the color paste dispersant comprises a third dispersant and a fourth dispersant, the third dispersant is at least one of polyacrylate ammonium salt, polyacrylate sodium salt, and modified polyurethane; the third dispersant has an adsorption heat of 20 kJ·mol -1 to 30 kJ·mol -1 , and the fourth dispersant is oleic acid with an adsorption heat of 50 kJ·mol -1 to 100 kJ·mol -1 .

[0012] As can be seen from the above solutions, the acidic group or ammonium salt group in the dispersant serves as a hydrophilic group to connect the inorganic pigment, avoiding the settlement of the inorganic pigment; the organic group at the other end is compatible with the solvent, improving the stability of the ink dispersion. The polyacrylate ammonium salt, polyacrylate sodium salt, and modified polyurethane are low-molecular-weight dispersants with low adsorption capacity, which maintain stability through electrostatic repulsion, but the electrostatic repulsion is easily destroyed by external force, and the stability of the color paste obtained is not high enough. The main chemical adsorption between oleic acid and inorganic pigments has a high adsorption heat, and an adsorption film is easily formed on the surface of the inorganic pigment, which causes the "lubrication" effect between the grinding medium and the pigment surface, reducing the grinding efficiency. Therefore, the combination of the two types of dispersants can effectively improve the grinding efficiency and grinding effect of the color paste while ensuring the stability of the ink.

[0013] Further, the inorganic pigment is at least one of copper-chromium black, red iron oxide, chromium oxide, aluminum oxide, titanium white, titanium-chromium yellow, titanium-nickel yellow, bismuth yellow, cobalt green, and cobalt blue.

[0014] As can be seen from the above solutions, the use of the above inorganic pigments enhances the acid and alkali resistance and light resistance.

[0015] Further, the inorganic pigment comprises red iron oxide, chromium oxide, and aluminum oxide, and the mass of the chromium oxide and the aluminum oxide is not more than 1 / 3 of the total content of the inorganic pigment.

[0016] As can be seen from the above solutions, red iron oxide has good weather resistance, light resistance, and heat resistance, and the addition of chromium oxide can increase the tinting strength and light resistance of the pigment, and the addition of aluminum oxide can improve the acid resistance and weather resistance of the pigment. The content of red iron oxide in the inorganic pigment accounts for 30%-55% of the percentage of the pigment dispersion color paste, and the content of chromium oxide and aluminum oxide is not more than 1 / 3 of the inorganic pigment, which further enhances the weather resistance of the ink on the basis of the red color.

[0017] Further, the inorganic pigment comprises titanium-chromium yellow, titanium-nickel yellow, and bismuth yellow, and the content of titanium-nickel yellow accounts for 40%-70% of the percentage of the pigment dispersion color paste, and the mass of titanium-chromium yellow and bismuth yellow is not more than 1 / 5 of the inorganic pigment.

[0018] From the above scheme, it can be seen that the above proportion setting makes the ink have excellent heat resistance, light resistance and weather resistance.

[0019] Further, the pigment ink for aluminum plate comprises 10-15% of pigment dispersion color paste, 3-5% of resin, 3-6% of ink dispersant, 0.5-1% of auxiliary agent and the balance of first solvent by mass percentage.

[0020] Further, the pigment dispersion color paste comprises 10-15% of color paste dispersant, 50-80% of inorganic pigment and the balance of second solvent by mass percentage.

[0021] From the above scheme, it can be seen that the above content of color paste dispersant and ink dispersant setting can ensure the dispersion stability of the pigment while preventing the solution viscosity from being too large to affect the fluidity of the color paste and the ink.

[0022] Further, the first solvent and the second solvent are both selected from at least one of dipropylene glycol methyl ether acetate, propylene glycol methyl ether, diethylene glycol dimethyl ether, monoalkyl ether and dialkyl ether of polyoxyethylene polyoxypropylene glycol.

[0023] Further, the auxiliary agent is defoaming agent and / or leveling agent.

[0024] From the above scheme, it can be seen that the above solvent adjusts the viscosity and surface tension of the ink, ensures that the ink fully penetrates and wets the aluminum plate, increases the contact area with the aluminum plate to enhance the adhesion, and at the same time meets the requirement of printing smoothness.

[0025] To achieve the second object of the present application, the present application provides a preparation method of a pigment ink for aluminum plate, which is used for preparing the pigment ink for aluminum plate according to any one of the above schemes, and the preparation method comprises the following steps: S1: mixing, stirring and uniformly dispersing inorganic pigment, color paste dispersant and second solvent, and then adding a grinding machine to grind to obtain pigment dispersion color paste; S2: stirring the pigment dispersion color paste and resin at 800 rpm-1000 rpm for 1-2 h to obtain solution one for standby; S3: stirring the first solvent, ink dispersant and auxiliary agent at 500 rpm-800 rpm for 0.5-1 h to obtain solution two for standby; S4: mixing solution one and solution two, and then continuing to stir at 800 rpm-1000 rpm for 1-1.5 h; and S5: filtering the solution after stirring in step S4 to obtain the pigment ink for aluminum plate.

[0026] To achieve the third object of the present application, the printing method of the pattern on the aluminum plate comprises the following steps: S1: printing the aluminum plate with the pigment ink on the aluminum plate substrate according to any of the above solutions; S2: placing the printed aluminum plate into a drying machine for drying and curing, the drying temperature is 150-200 DEG C, and the drying time is 5-10 min.

[0027] From the above solutions, the drying temperature is set to 150-200 DEG C, avoiding the problems of insufficient drying of the coating, mutual adhesion of the plates, and paint peeling caused by too low temperature, and avoiding the problems of yellowing and softening of the plate base caused by too high temperature. Within the above temperature range, the epoxy resin has good fluidity and plasticity, easily combines with the pigment to form a solid whole, and enhances the color fastness and abrasion resistance.

[0028] The present application first enhances the adhesion of inorganic pigments on the aluminum plate, utilizes the excellent bonding strength between the epoxy resin and the metal aluminum plate at room temperature, and forms a chemical bond with stronger interaction force between the metal aluminum plate by heating the epoxy resin to open the ring, thereby solving the problem of easy dispersion of inorganic pigments on the aluminum plate. Further, the molecular weight of the epoxy resin is optimized to improve the printing fluency. In addition, the ratio of the color paste and the epoxy resin is optimized to improve the cracking problem of the epoxy resin and enhance the impact resistance of the ink layer on the aluminum plate. Secondly, in order to enhance the weather resistance of the ink, inorganic pigments are used. By adjusting the ratio of different inorganic pigments, the acid resistance, heat resistance, light resistance and weather resistance of the ink are further enhanced on the basis of obtaining the required color. The specific dispersant is matched with the inorganic pigment to obtain a pigment dispersion color paste with good grinding effect. Finally, the curing temperature and time are adjusted to further enhance the color fastness and abrasion resistance of the ink. DETAILED DESCRIPTION

[0029] The present application provides a pigment ink for aluminum plate, which comprises 10-15% of pigment dispersion color paste, 3-5% of resin, 3-6% of ink dispersant, 0.5-1% of auxiliary agent and the balance of first solvent, by mass percentage.

[0030] The pigment dispersion color paste comprises 10-15% of color paste dispersant, 50-80% of inorganic pigment and the balance of second solvent.

[0031] The color paste dispersant comprises third dispersant and fourth dispersant, the third dispersant is at least one of polyacrylate ammonium salt, polyacrylate sodium salt and modified polyurethane, the adsorption heat of the third dispersant is 20-30 kJ·mol -1 . -1 The specific model includes AH-105X (polyacrylate sodium salt), 5028A and D-410, the fourth dispersant has an adsorption heat of 50 kJ·mol -1 to 100 kJ·mol -1 Oleic acid, specific models include oleic acid 0880, oleic acid 0870 and oleic acid 0845.

[0032] The inorganic pigment is selected from at least one of copper chrome black, iron oxide red, chromium oxide, aluminum oxide, titanium white, titanium chrome yellow, titanium nickel yellow, bismuth yellow, cobalt green and cobalt blue.

[0033] When the ink is red, the inorganic pigments include red iron oxide, chromium oxide and aluminum oxide, wherein the content of red iron oxide in the inorganic pigments accounts for 30%-55% of the pigment dispersion paste, and the total mass of chromium oxide and aluminum oxide does not exceed 1 / 3 of the inorganic pigments.

[0034] When the ink is yellow, the inorganic pigments include titanium chrome yellow, titanium nickel yellow and bismuth yellow, wherein the content of titanium nickel yellow accounts for 40%-70% of the pigment dispersion paste, and the total mass of titanium chrome yellow and bismuth yellow does not exceed 1 / 5 of the inorganic pigments.

[0035] The second solvent is selected from at least one of dipropylene glycol methyl ether acetate, propylene glycol methyl ether, diethylene glycol dimethyl ether, and monoalkyl ethers and dialkyl ethers of polyoxyethylene and polyoxypropylene glycol.

[0036] The resin is epoxy resin with a molecular weight of 800 to 2000 and a shrinkage of 0.5% to 1.2%. Specific models include DER6508 (shrinkage of 0.5%-0.9%, molecular weight of 850-900) and DER6510HT (shrinkage of 0.5%-1.2%, molecular weight of 880-950). The mass ratio of the pigment dispersion paste to the epoxy resin is 1.5-2.0:1.

[0037] The ink dispersant includes a first dispersant and a second dispersant, wherein the first dispersant is at least one of polyacrylate ammonium salt, polyacrylate sodium salt, and modified polyurethane, and the adsorption heat of the first dispersant is 20 kJ·mol -1 to 30 kJ·mol -1 Specific models include AH-105X (sodium polyacrylate), 5028A and D-410, the second dispersant is an adsorption heat of 50 kJ·mol -1 to 100 kJ·mol -1 Oleic acid, specific models include oleic acid 0880, oleic acid 0870 and oleic acid 0845.

[0038] The adjuvant is a defoaming agent and / or a leveling agent. The defoaming agent is selected from BYK-065, and the leveling agent is selected from one or more of BYK-310, BYK-322, BYK-331, and BYK-378.

[0039] The first solvent is selected from at least one of dipropylene glycol methyl ether acetate, propylene glycol methyl ether, diethylene glycol dimethyl ether, monoalkyl ethers of polyoxyethylene polyoxypropylene glycol, and dialkyl ethers.

[0040] The preparation method of the pigment ink for aluminum plate of the present application is used to prepare the above-mentioned pigment ink for aluminum plate, and comprises the following steps:

[0041] S1: After the inorganic pigment, the color paste dispersant, and the second solvent are uniformly dispersed by mixing and stirring, the grinding machine is added for grinding to obtain a pigment dispersion color paste;

[0042] S2: The pigment dispersion color paste and the resin are stirred at 800 rpm to 1000 rpm for 1 h to 2 h to obtain solution one for standby;

[0043] S3: The first solvent, the ink dispersant, and the adjuvant are stirred at 500 rpm to 800 rpm for 0.5 h to 1 h to obtain solution two for standby;

[0044] S4: After the solution one and the solution two are mixed, they are continuously stirred at 800 rpm to 1000 rpm for 1 h to 1.5 h;

[0045] S5: The solution after stirring in step S4 is filtered to obtain the pigment ink for aluminum plate.

[0046] The printing method of the pattern on the aluminum plate of the present application comprises the following steps:

[0047] S1: The above-mentioned pigment ink for aluminum plate is printed on the aluminum plate substrate;

[0048] S2: The printed aluminum plate is placed in a drying machine for drying and curing, the drying temperature is 150℃ to 200℃, and the drying time is 5 min to 10 min.

[0049] The following is described in combination with specific embodiments.

[0050] Preparation of the pigment dispersion color paste

[0051] The pigment dispersion color paste is configured according to the mass percentage composition shown in Table 1.

[0052] Table 1

[0053]

[0054]

[0055] The pigment dispersion color paste was prepared as follows: 10% to 15% of the color paste dispersant, 50% to 80% of the inorganic pigment, and the balance of the second solvent were added to a grinding machine, and then zirconium oxide beads with a diameter of 0.6 mm to 0.8 mm were filled into the grinding machine to a volume of 75% to 80% of the capacity of the vessel. Next, the grinding machine filled with the zirconium beads was used to grind the color paste at a temperature of 25°C and a rotational speed of 2000 rpm for 240 min. The ground color paste was further filtered through a glass fiber membrane with a pore size of 0.8 μm to 1.0 μm at a filtration rate of 150 g in 1.5 min. The pigment dispersion color paste obtained after filtration had a particle size (D50) of 100 nm to 200 nm.

[0056] It should be noted that in the above pigment dispersion color paste, the sodium polyacrylate and the oleic acid used were of the same type.

[0057] Preparation of pigment ink for aluminum plate

[0058] The pigment ink for aluminum plate was prepared according to the mass percentages shown in Tables 2 and 3.

[0059] Table 2

[0060]

[0061]

[0062] Table 3

[0063]

[0064]

[0065] It should be noted that in the above ink, the epoxy resin with a shrinkage of 0.5% was an epoxy resin of the same type, and the epoxy resin with a shrinkage of 1.2% was an epoxy resin of the same type. The epoxy resin with a shrinkage of 2% in Comparative Example 2 was DYMAX 9906-AA, and the acrylic resin with a shrinkage of 0.5% in Comparative Example 9 was P-TA3012.

[0066] The pigment ink for aluminum plate was prepared as follows: S1 : the pigment dispersion color paste and the resin were stirred at 800 rpm to 1000 rpm for 1 h to 2 h to obtain solution one for standby; S2: the first solvent, the ink dispersant, and the auxiliary agent were stirred at 500 rpm to 800 rpm for 0.5 h to 1 h to obtain solution two for standby; S3: after mixing solution one and solution two, the mixture was further stirred at 800 rpm to 1000 rpm for 1 h to 1.5 h; and S4: the solution after stirring in step S3 was filtered through a filter membrane with a pore size of 0.8 μm to 1.0 μm to obtain the pigment ink for aluminum plate.

[0067] The aluminum plates of the above examples and comparative examples were printed on the aluminum plate substrate with pigment ink, and the printed aluminum plates were placed in a drying machine for drying and curing, with a drying temperature of 200°C and a drying time of 5 min. The aluminum plate coating of Comparative Example 8 was dried in an oven at 100°C for 5 min.

[0068] Performance tests were performed on the above examples and comparative examples

[0069] 1. Acid resistance

[0070] 100 mL of 60%-68% mass fraction of analytical pure nitric acid (HNO3) was poured into a wide-mouth bottle with a capacity of 250 mL, so that the reagent filled 1 / 2 of the volume of the wide-mouth bottle. The aluminum plate coating was placed upside down on the bottle mouth for 30 min, then was placed at an angle of 45° under a tap water faucet to flush the acid reaction surface for 1 min. The surface was wiped dry with gauze, and the coating changes were observed immediately after standing for 1 h. The color density of the coating on the acid exposed and unexposed surfaces was measured with a color difference meter, and the acid resistance level was determined according to the color density, wherein: Grade A: color density greater than 1.6; Grade B: color density in the range of 1.3-1.6; Grade C: color density less than 1.3.

[0071] 2. Alkali resistance

[0072] A 10% sodium hydroxide solution was dropped onto the aluminum plate coating, and a glass sheet was placed on top to allow the sodium hydroxide solution to remain on the surface for ten minutes. Finally, the glass sheet was removed, and the surface of the layer was washed with tap water and wiped dry with gauze. The coating changes were observed immediately after standing for 1 h. The color density of the coating on the acid exposed and unexposed surfaces was measured with a color difference meter, and the acid resistance level was determined according to the color density, wherein: Grade A: color density greater than 1.6; Grade B: color density in the range of 1.3-1.6; Grade C: color density less than 1.3.

[0073] 3. Adhesion

[0074] A blade was used to draw 10x10 small grids of 1 mm x 1 mm on the surface of the aluminum plate color block, and then 3M No. 600 adhesive tape was firmly adhered to the tested small grids, and the tape was quickly pulled off at an angle of approximately 60°. The adhesion level was determined according to the surface shedding, wherein: Grade A: the edges of the scribe lines are smooth or there are small pieces of imprint shedding at the intersection points of the scribe lines; Grade B: there are pieces of imprint shedding at the edges and intersection points of the scribe lines, with a shedding area of 10%-20%; Grade C: the degree of shedding exceeds Grade B.

[0075] 4. Impact resistance

[0076] The impact resistance of the aluminum plate coating is determined by the method of GB1732-1993, and the impact resistance level is determined according to the surface crack, wrinkle or peeling phenomenon, wherein: A level: no obvious crack phenomenon; B level: a few wrinkle phenomenon; C level: surface peeling phenomenon.

[0077] The above test results are shown in Table 4 below.

[0078] Table 4

[0079]

[0080]

[0081] From the above scheme, it can be seen that the ink of Comparative Example 1 does not add epoxy resin relative to Example 1; the shrinkage of the epoxy resin in the ink of Comparative Example 2 is too high, which exceeds the range of 0.5% to 1.2%; the inorganic pigment in the ink of Comparative Example 3 is only iron oxide red relative to Example 3; the inorganic pigment in the ink of Comparative Example 4 is only titanium nickel yellow relative to Example 4; the pigment used in the ink of Comparative Example 5 is an organic pigment relative to Example 5; the mass ratio of pigment paste to epoxy resin in the ink of Comparative Example 6 is less than (1.5-2.0):1 relative to Example 6; the mass ratio of pigment paste to epoxy resin in the ink of Comparative Example 7 is greater than (1.5-2.0):1 relative to Example 7; the drying temperature of the aluminum plate in Comparative Example 8 is different from that of Example 8, the drying temperature of the aluminum plate in Example 8 is 200°C, and the drying temperature of the aluminum plate in Comparative Example 8 is 100°C; the resin used in the ink of Comparative Example 9 is acrylate relative to Example 9; and the dispersing agent used in the ink of Comparative Example 10 is polyacrylic acid sodium relative to Example 9.

[0082] As can be seen from the above comparative examples, the pigment ink for aluminum plate of the present application has bright color, excellent adhesion to aluminum plate, good acid and alkali resistance, and strong impact resistance.

[0083] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of various changes or replacements within the technical range disclosed in the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A pigment ink for aluminum plate, comprising a pigment dispersion paste and a resin, characterized in that: The pigment dispersion paste includes an inorganic pigment, the resin is an epoxy resin, the molecular weight of the epoxy resin is 800 to 2000, and the shrinkage rate of the epoxy resin is 0.5% to 1.2%; In terms of mass percentage, the mass ratio of the pigment dispersion paste to the epoxy resin is (1.5-2.0): 1; The pigment ink for aluminum plate further includes an ink dispersant, the ink dispersant including a first dispersant and a second dispersant, the first dispersant being at least one of polyacrylate ammonium salt, polyacrylate sodium salt, and modified polyurethane; the first dispersant having an adsorption heat of 20 kJ·mol-1 to 30 kJ·mol-1, and the second dispersant being oleic acid having an adsorption heat of 50 kJ·mol-1 to 100 kJ·mol-1; The inorganic pigment is selected from at least one of copper chrome black, titanium white, cobalt green and cobalt blue; or the inorganic pigment includes iron oxide red, chromium oxide and aluminum oxide, wherein the total mass of the chromium oxide and the aluminum oxide does not exceed 1 / 3 of the inorganic pigment; or the inorganic pigment includes titanium chrome yellow, titanium nickel yellow and bismuth yellow, wherein the total mass of the titanium chrome yellow and the bismuth yellow does not exceed 1 / 5 of the inorganic pigment.

2. The pigment ink for aluminum plate according to claim 1, characterized in that: The pigment dispersion paste also includes a paste dispersant, and the paste dispersant includes a third dispersant and a fourth dispersant. The third dispersant is at least one of ammonium polyacrylate, sodium polyacrylate, and modified polyurethane; the adsorption heat of the third dispersant is 20 kJ·mol-1 to 30 kJ·mol-1, and the fourth dispersant is oleic acid with an adsorption heat of 50 kJ·mol-1 to 100 kJ·mol-1.

3. The pigment ink for aluminum plate according to claim 1 or 2, characterized in that: Calculated by mass percentage, the pigment ink for aluminum plate includes 10% to 15% of the pigment dispersion paste, 3% to 5% of the resin, 3% to 6% of the ink dispersant, 0.5% to 1% of the auxiliary agent and the balance of the first solvent.

4. The pigment ink for aluminum plate according to claim 3, characterized in that: Calculated by mass percentage, the pigment dispersion paste includes 10% to 15% of a paste dispersant, 50% to 80% of the inorganic pigment, and the balance a second solvent.

5. A method for preparing a pigment ink for aluminum plate, the method being used to prepare the pigment ink for aluminum plate according to claim 4, characterized in that The preparation method comprises the following steps: S1: After the inorganic pigment, color paste dispersant and second solvent are mixed and stirred to be uniformly dispersed, the mixture is added to a grinder for grinding to obtain a pigment dispersion paste; S2: stirring the pigment dispersion paste and the resin at 800 rpm to 1000 rpm for 1 to 2 hours to obtain a solution 1 for later use; S3: Stir the first solvent, ink dispersant and additive at 500 rpm to 800 rpm for 0.5 h to 1 h to obtain a second solution for later use; S4: After mixing the solution 1 and the solution 2, continue stirring at 800 rpm to 1000 rpm for 1 h to 1.5 h; S5: Filter the solution stirred in step S4 to obtain the pigment ink for the aluminum plate.

6. A method for printing a pattern on an aluminum plate, characterized in that: The printing method comprises the following steps: S1: printing the pigment ink for an aluminum plate according to any one of claims 1 to 4 onto an aluminum plate substrate; S2: Place the printed aluminum plate in a dryer for drying and curing. The drying temperature is 150°C to 200°C and the drying time is 5 minutes to 10 minutes.

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