Pigment ink for aluminum plate, preparation method of pigment ink and printing method of pattern on aluminum plate

Abstract

The invention provides pigment ink for an aluminum plate, a preparation method of the pigment ink and a printing method of patterns on the aluminum plate, the ink comprises pigment dispersion color paste and resin, the pigment dispersion color paste comprises inorganic pigment, the resin is 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. The epoxy resin and the aluminum plate form covalent bonds under the heating condition, and the problem that the adhesive force of the pigment on the aluminum plate is not strong is solved. On the basis of enhancing the adhesive force, the selected pigment is an inorganic pigment, so that the acid resistance and the weather resistance are high. The proportion of the color paste to the resin is regulated and controlled, certain toughness is achieved on the premise that the hardness is kept, cracking during impact is avoided, and the impact strength of the composite material is improved.

Description

Technical Field

[0001] The invention relates to the field of digital inkjet, and in particular to a pigment ink for an aluminum plate and a preparation method thereof, and a method for printing a pattern on an aluminum plate. Background Art

[0002] Aluminum plates have the advantages of light weight, high strength, corrosion resistance, easy processing, good electrical and thermal conductivity, easy processing and forming, convenient and quick construction, and high recycling value. They are 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 plates is to print on their surface. One of the main printing methods is anodizing, which forms an oxide film on the metal surface by 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 method 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. These methods cannot meet the application requirements of aluminum plates. In addition, the surface of the aluminum plate is smooth, and it is difficult for organic pigment particles to adhere to the surface of the aluminum plate, and the ink layer is easy to fall off. Summary of the invention

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

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

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

[0007] To achieve the first purpose of the present invention, a pigment ink for aluminum plate of the present invention includes a pigment dispersion paste and a resin, 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.

[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 on 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, which meets the requirements of adhesion. At the same time, it also avoids the problem of excessive molecular weight, resulting in excessive steric hindrance, excessive ink viscosity causing 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] Too large will cause cracking of the epoxy resin film layer, and epoxy resin with lower shrinkage will greatly increase the preparation cost of the ink. Therefore, controlling the shrinkage of epoxy resin within the range of 0.5% to 1.2% can achieve the goal of avoiding cracking of the epoxy resin film while effectively controlling the cost. The mass ratio of pigment dispersion paste to epoxy resin is limited to (1.5-2.0):1, which makes up for the shortcomings of epoxy resin itself, such as large brittleness, poor toughness, and poor impact performance. By adding pigment particles and using the pigment particles to be evenly dispersed in the epoxy resin, when the material is impacted by external force, silver streaks will be generated between the particles and the matrix, absorbing a certain amount of deformation work. The matrix between the particles also produces plastic deformation and absorbs a certain amount of impact energy. When the silver streaks diffuse in the resin, they are hindered and passivated by the particles and eventually stop, preventing destructive cracking, thus achieving the toughening effect. By limiting the ratio between the color paste and the epoxy resin, a certain toughness is obtained while maintaining the hardness, avoiding 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 comprises an ink dispersant, the ink dispersant comprises 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 Up to 30 kJ·mol -1 The second dispersant has an adsorption heat of 50 kJ·mol -1 Up to 100 kJ·mol -1 of oleic acid.

[0011] A further solution is that the pigment dispersion paste further includes a paste dispersant, the paste dispersant includes 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 adsorption heat of the third dispersant is 20 kJ·mol -1 Up to 30 kJ·mol -1 The fourth dispersant has an adsorption heat of 50 kJ·mol -1 Up to 100 kJ·mol -1 of oleic acid.

[0012] It can be seen from the above scheme that the acidic group or ammonium salt group in the dispersant acts as a hydrophilic group to connect the inorganic pigment to avoid the sedimentation of the inorganic pigment; the organic group at the other end is compatible with the solvent to improve the stability of the ink dispersion. Ammonium polyacrylate, sodium polyacrylate and modified polyurethane are low molecular weight dispersants with low adsorption capacity. They maintain stability through charge repulsion, but the electrostatic repulsion is easily destroyed by external forces, and the stability of the obtained color paste is not high enough; oleic acid and inorganic pigments mainly undergo chemical adsorption, with high adsorption heat, and it is easy to form an adsorption film on the surface of the inorganic pigment. The formation of the adsorption film will cause the grinding medium to "lubricate" the pigment surface, reducing the grinding efficiency. Therefore, through the combined use of the two types of dispersants, the synergistic effect effectively improves the grinding efficiency and grinding effect of the color paste while ensuring the stability of the ink.

[0013] In a further embodiment, the inorganic pigment is selected from at least one of copper chrome black, red iron oxide, chromium oxide, aluminum oxide, titanium white, titanium chrome yellow, titanium nickel yellow, bismuth yellow, cobalt green and cobalt blue.

[0014] It can be seen from the above scheme that the use of the above inorganic pigments can enhance the acid and alkali resistance and light resistance and other properties.

[0015] A further solution is that the inorganic pigment includes red iron oxide, chromium oxide and aluminum oxide, wherein the mass sum of the chromium oxide and the aluminum oxide does not exceed 1 / 3 of the total content of the inorganic pigment.

[0016] As can be seen from the above scheme, red iron oxide has good weather resistance, light resistance and heat resistance. In addition, adding chromium oxide can increase the pigment's tinting power and light resistance, while adding aluminum oxide can improve the pigment's acid resistance and weather resistance. The content of red iron oxide in inorganic pigments accounts for 30%-55% of the pigment dispersion paste, and the content of chromium oxide and aluminum oxide does not exceed 1 / 3 of the inorganic pigment, which makes the color appear red and further enhances the weather resistance of the ink.

[0017] A further solution is that 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.

[0018] It can be seen from the above scheme that the above ratio setting enables the ink to have excellent heat resistance, light resistance and weather resistance.

[0019] A further solution is that, by mass percentage, the pigment ink for aluminum plate includes 10% to 15% of pigment dispersion paste, 3% to 5% of resin, 3% to 6% of ink dispersant, 0.5% to 1% of auxiliary agent and the balance of the first solvent.

[0020] A further solution is that, by mass percentage, the pigment dispersion paste includes 10% to 15% of a paste dispersant, 50% to 80% of an inorganic pigment and the remainder of a second solvent.

[0021] It can be seen from the above scheme that the above contents of the color paste dispersant and the ink dispersant are set to ensure the dispersion stability of the pigment while preventing the viscosity of the solution from being too high, which affects the fluidity of the color paste and the ink.

[0022] In a further embodiment, 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, and monoalkyl ethers and dialkyl ethers of polyoxyethylene polyoxypropylene glycol.

[0023] In a further embodiment, the auxiliary agent is a defoaming agent and / or a leveling agent.

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

[0025] To achieve the second purpose of the present invention, a method for preparing a pigment ink for aluminum plate of the present invention is used to prepare a pigment ink for aluminum plate described in any of the above schemes, and the preparation method comprises the following steps: S1: After the inorganic pigment, color paste dispersant and second solvent are mixed and stirred to be evenly dispersed, they are added into a grinder for grinding to obtain a pigment dispersion color paste; S2: The pigment dispersion color paste and resin are stirred at 800rpm~1000rpm for 1h~2h to obtain a solution one for standby use; S3: The first solvent, ink dispersant and auxiliary agent are stirred at 500rpm~800rpm for 0.5h~1h to obtain a solution two for standby use; S4: After mixing solution one and solution two, continue to stir at 800rpm~1000rpm for 1h~1.5h; S5: Filter the solution stirred in step S4 to obtain a pigment ink for aluminum plate.

[0026] To achieve the third purpose of the present invention, a method for printing a pattern on an aluminum plate of the present invention comprises the following steps: S1: printing an aluminum plate described in any of the above schemes with pigment ink onto an aluminum plate substrate; S2: placing the printed aluminum plate in a dryer for drying and curing, the drying temperature being 150°C to 200°C, and the drying time being 5min to 10min.

[0027] It can be seen from the above scheme that the drying temperature is set to 150℃~200℃ to avoid problems such as insufficient coating drying, board adhesion and paint peeling due to too low temperature; it can also avoid problems such as yellowing and softening of the board base due to too high temperature. Within the above temperature, epoxy resin has good fluidity and plasticity, and is easy to combine with pigments to form a solid whole, thereby enhancing color fastness and abrasion resistance.

[0028] The present invention firstly enhances the adhesion of inorganic pigments on aluminum plates, utilizes the excellent bonding strength between epoxy resin and metal aluminum plates at room temperature, and heats the epoxy resin to open the ring, thereby forming a chemical bond with stronger interaction force with the metal aluminum plate, solving the problem that inorganic pigments are easy to spread on aluminum plates. The molecular weight of epoxy resin is further optimized to improve printing fluency. In addition, the ratio of color paste to epoxy resin is optimized to improve the problem of easy cracking of epoxy resin and enhance the impact resistance of the ink layer on the aluminum plate. Secondly, in order to enhance the weather resistance of ink, inorganic pigments are used. By regulating the ratio between different inorganic pigments, the acid resistance, heat resistance, light resistance and weather resistance of ink are further enhanced on the basis of obtaining the desired color. The combination of specific dispersants and inorganic pigments obtains pigment dispersion color paste with good grinding effect. Finally, the curing temperature and time are regulated to further enhance the color fastness and abrasion resistance of ink. DETAILED DESCRIPTION

[0029] The invention provides a pigment ink for aluminum plates. The pigment ink for aluminum plates comprises, by mass percentage, 10% to 15% of a pigment dispersion paste, 3% to 5% of a resin, 3% to 6% of an ink dispersant, 0.5% to 1% of an auxiliary agent and the remainder of a first solvent.

[0030] The pigment dispersion paste comprises 10% to 15% of a paste dispersant, 50% to 80% of an inorganic pigment and the remainder of a second solvent.

[0031] The color paste dispersant includes 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 adsorption heat of the third dispersant is 20 kJ·mol -1 Up to 30 kJ·mol -1 Specific models include AH-105X (sodium polyacrylate), 5028A and D-410, the fourth dispersant is an adsorption heat of 50 kJ·mol -1 Up 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, red iron oxide, 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 pigment accounts for 30%-55% of the pigment dispersion paste, and the mass of chromium oxide and aluminum oxide does not exceed 1 / 3 of the inorganic pigment.

[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 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 glycols of polyoxyethylene polyoxypropylene glycol.

[0036] The resin is epoxy resin, the molecular weight of the epoxy resin is 800 to 2000, the shrinkage of the epoxy resin is 0.5% to 1.2%, and the specific models include DER6508 (shrinkage: 0.5%-0.9%, molecular weight: 850-900), DER6510HT (shrinkage: 0.5%-1.2%, molecular weight: 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, 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 Up 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 Up to 100 kJ·mol -1 Oleic acid, specific models include oleic acid 0880, oleic acid 0870 and oleic acid 0845.

[0038] The auxiliary agent is a defoamer and / or a leveling agent. The defoamer 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, and monoalkyl ethers and dialkyl ethers of polyoxyethylene polyoxypropylene glycol.

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

[0041] S1: After the inorganic pigment, the color paste dispersant and the second solvent are mixed and stirred to be uniformly dispersed, the mixture is added to a grinder for grinding to obtain a pigment dispersion color paste;

[0042] S2: Stir the pigment dispersion paste and the resin at 800 rpm to 1000 rpm for 1 h to 2 h to obtain a solution 1 for later use;

[0043] S3: stirring 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 standby use;

[0044] S4: After mixing solution 1 and solution 2, continue stirring at 800 rpm to 1000 rpm for 1 h to 1.5 h;

[0045] S5: Filter the solution stirred in step S4 to obtain pigment ink for aluminum plate.

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

[0047] S1: printing the above-mentioned one aluminum plate with pigment ink onto an aluminum plate substrate;

[0048] S2 puts the printed aluminum plate into a dryer for drying and curing, the drying temperature is 150°C to 200°C, and the drying time is 5min to 10min.

[0049] The following is a description with reference to specific embodiments.

[0050] Preparation of pigment dispersion paste

[0051] The pigment dispersion paste was prepared according to the mass percentage composition shown in Table 1.

[0052] Table 1

[0053]

[0054]

[0055] The preparation method of the pigment dispersion paste is as follows: 10% to 15% of the paste dispersant, 50% to 80% of the inorganic pigment and the balance of the second solvent are added to the grinder, and then zirconium oxide beads with a diameter of 0.6 mm to 0.8 mm are filled into the above grinder to make its volume reach 75% to 80% of the container capacity. Next, the grinder filled with zirconium beads is used to grind the paste at a temperature of 25°C and a speed of 2000 rpm for 240 minutes. The grinded paste is further filtered through a 0.8μm to 1.0μm glass fiber membrane, and the filtration rate is 150g filtered within 1.5 minutes. The particle size (D50) of the pigment dispersion paste obtained after filtration is 100nm to 200nm.

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

[0057] Preparation of pigment ink for aluminum plate

[0058] The pigment ink for aluminum plate is configured according to the mass percentage composition shown in Tables 2 and 3 below.

[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 rate of 0.5% is the same type of epoxy resin, and the epoxy resin with a shrinkage rate of 1.2% is the same type of epoxy resin. The epoxy resin with a shrinkage rate of 2% in Comparative Example 2 is DYMAX 9906-AA; the acrylic resin with a shrinkage rate of 0.5% in Comparative Example 9 is P-TA3012.

[0066] The preparation method of pigment ink for aluminum plate is as follows: S1: Stir the pigment dispersion paste and resin at 800rpm~1000rpm for 1h~2h to obtain solution 1 for standby; S2: Stir the first solvent, ink dispersant and auxiliary agent at 500rpm~800rpm for 0.5h~1h to obtain solution 2 for standby; S3: After mixing solution 1 and solution 2, continue to stir at 800rpm~1000rpm for 1h~1.5h; S:4: Filter the solution stirred in step S3 through a 0.8μm~1.0μm filter membrane to obtain pigment ink for aluminum plate.

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

[0068] The above embodiments and comparative examples were tested for performance

[0069] 1. Acid resistance

[0070] Pour 100mL of analytical pure nitric acid (HNO3) with a mass fraction of 60% to 68% into a 250mL wide-mouth bottle, filling the reagent to 1 / 2 of the volume of the wide-mouth bottle. Cover the aluminum plate with the coating facing down on the bottle mouth for 30 minutes, then tilt it at a 45° angle under the tap to rinse the acid reaction surface for 1 minute, wipe it dry with gauze, and observe the coating changes immediately after standing for 1 hour. Use a colorimeter to measure the color density of the coating on the acid-exposed and unexposed surfaces, and judge the acid resistance level according to the color density, where: Grade A: color density greater than 1.6; Grade B: color density range of 1.3-1.6; Grade C: color density less than 1.3.

[0071] 2. Alkali resistance

[0072] Drop 10% sodium hydroxide solution on the aluminum plate coating, cover it with a glass sheet, let the sodium hydroxide solution stay on the surface for ten minutes, finally remove the glass sheet, clean the surface of the layer with tap water, wipe it dry with gauze, and observe the changes in the coating immediately after standing for 1 hour. Use a colorimeter to measure the color density of the acid-exposed and unexposed surface coatings, and judge the acid resistance level based on the color density, where: Grade A: color density greater than 1.6; Grade B: color density range of 1.3-1.6; Grade C: color density less than 1.3.

[0073] 3. Adhesion

[0074] Use a blade to draw 10×10 1mm×1mm small grids on the surface of the aluminum plate color block, then use 3M No. 600 tape to firmly stick to the tested small grid, and quickly tear off the tape at a direction close to 60°; determine the adhesion level based on the surface shedding situation, among which: Grade A: the edge of the line is smooth or small pieces of prints fall off at the intersection of the lines; Grade B: There are pieces of prints falling off at the edges and intersections of the lines, and the shedding area is 10%-20%; Grade C: The degree of shedding exceeds Grade B.

[0075] 4. Impact resistance

[0076] The impact resistance of aluminum plate coating is measured by the method of GB1732-1993, and the impact resistance level is determined according to the cracks, wrinkles or peeling on the surface, among which: Grade A: no obvious cracks; Grade B: a few wrinkles; Grade C: surface peeling.

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

[0078] Table 4

[0079]

[0080]

[0081] It can be seen from the above scheme that no epoxy resin is added to the ink of Example 1; the shrinkage rate of the epoxy resin in the ink of Example 2 is too high, exceeding the range of 0.5% to 1.2%; in the ink of Example 3, only red iron oxide is used as the inorganic pigment; in the ink of Example 4, only titanium nickel yellow is used as the inorganic pigment; in the ink of Example 5, organic pigment is used as the pigment; in the ink of Example 6, the mass ratio of the pigment paste to the epoxy resin is less than (1.5 to 2.0):1; in the ink of Example 7, the mass ratio of the pigment paste to the epoxy resin is greater than (1.5 to 2.0):1; the drying temperature of Example 8 is different from that of Example 8, the drying temperature of the aluminum plate of Example 8 is 200°C, and the drying temperature of the aluminum plate of Example 8 is 100°C; the resin used in the ink of Example 9 is acrylate; the dispersant used in the ink of Example 10 is sodium polyacrylate.

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

[0083] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of various changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on 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%; Calculated by mass percentage, the mass ratio of the pigment dispersion paste to the epoxy resin is (1.5-2.0):

1.

2. The pigment ink for aluminum plate according to claim 1, characterized in that: The pigment ink for aluminum plate further comprises an ink dispersant, wherein the ink dispersant comprises a first dispersant and a second dispersant, wherein the first dispersant is at least one of ammonium polyacrylate, sodium polyacrylate, and modified polyurethane; and the adsorption heat of the first dispersant is 20 kJ·mol -1 Up to 30 kJ·mol -1 The second dispersant has an adsorption heat of 50 kJ·mol -1 Up to 100 kJ·mol -1 of oleic acid.

3. The pigment ink for aluminum plate according to claim 1, characterized in that: The pigment dispersion paste further includes a paste dispersant, and the paste dispersant includes a third dispersant and a fourth dispersant, and 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 kJ·mol -1 Up to 30 kJ·mol -1 The fourth dispersant has an adsorption heat of 50 kJ·mol -1 Up to 100 kJ·mol -1 of oleic acid.

4. The pigment ink for aluminum plate according to claim 1, characterized in that: The inorganic pigment is selected from at least one of copper chrome black, red iron oxide, chromium oxide, aluminum oxide, titanium white, titanium chrome yellow, titanium nickel yellow, bismuth yellow, cobalt green and cobalt blue.

5. The pigment ink for aluminum plate according to claim 4, characterized in that: The inorganic pigment comprises red iron oxide, chromium oxide and aluminum oxide, wherein the mass sum of the chromium oxide and the aluminum oxide does not exceed 1 / 3 of the inorganic pigment.

6. The pigment ink for aluminum plate according to claim 4, characterized in that: The inorganic pigments include titanium chrome yellow, titanium nickel yellow and bismuth yellow, wherein the mass sum of the titanium chrome yellow and the bismuth yellow is no more than 1 / 5 of the inorganic pigments.

7. The pigment ink for aluminum plate according to any one of claims 1 to 6, 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.

8. The pigment ink for aluminum plate according to any one of claims 1 to 6, 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 of a second solvent.

9. A method for preparing a pigment ink for aluminum plate, the method being used to prepare a pigment ink for aluminum plate as claimed in claims 1 to 8, characterized in that The preparation method comprises the following steps: S1: After the inorganic pigment, the color paste dispersant and the second solvent are mixed and stirred to be uniformly dispersed, the mixture is added to a grinder for grinding to obtain a pigment dispersion color paste; S2: Stirring the pigment dispersion paste and the resin at 800 rpm to 1000 rpm for 1 h to 2 h to obtain a solution 1 for later use; S3: stirring the first solvent, ink dispersant and auxiliary agent at 500 rpm to 800 rpm for 0.5 h to 1 h to obtain a second solution for standby 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: filtering the solution stirred in step S4 to obtain the pigment ink for the aluminum plate.

10. A method for printing a pattern on an aluminum plate, characterized in that: The printing method comprises the following steps: S1: printing an aluminum plate pigment ink as claimed in any one of claims 1 to 8 onto an aluminum plate substrate; S2 puts the printed aluminum plate into a dryer for drying and curing, the drying temperature is 150°C to 200°C, and the drying time is 5min to 10min.

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