Preparation method of aluminum pigment for water-based ink

Abstract

The invention discloses a preparation method of an aluminum pigment for water-based ink. The preparation method comprises the following steps: forming a phosphate coating layer on the surface of the aluminum pigment through phosphate; forming a silicon coating layer on the surface of the aluminum pigment through a silane coupling agent and tetraethoxysilane; a phosphate-modified water-based resin coating layer is formed on the surface of the aluminum pigment through phosphate-modified water-based resin. The preparation method of the aluminum pigment for the water-based ink, provided by the invention, has the following beneficial effects that through surface passivation of phosphate ester, the compactness of silicon coating is ensured, and the hue loss of the aluminum pigment is reduced; a silane coupling agent with amino groups is introduced, so that the phosphate coating layer is coated with a silicon coating layer; the phosphate modified water-based resin is introduced, so that the produced aluminum pigment can be better dispersed in water-based ink.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum pigments, and in particular to a method for preparing aluminum pigments for water-based inks. Background Art

[0002] Water-based ink uses water as solvent or dispersant, and has lower VOC emissions than oil-based ink, making it more environmentally friendly. In addition, water-based ink also has advantages such as bright color, fast drying speed, and strong adhesion, which can meet the needs of different printing processes. Therefore, the research and development and application of water-based ink has gradually become an important development direction of the ink industry.

[0003] In the ink industry, aluminum pigments have given new value and charm to ink products with their excellent performance and unique metallic luster. The metallic luster of aluminum pigments not only brings a bright appearance to the ink, but also significantly increases the added value of the product, making the product more competitive in the market. However, in the water-based ink system, it contains a large amount of water and is weakly alkaline. At this time, water will react with aluminum pigments to generate aluminum oxide and aluminum hydroxide, and release hydrogen. The reaction equation is as follows:

[0004] 2Al+3H 2 O→2Al 2 O 3 +3H 2 ↑

[0005] 2Al+6H 2 O→2Al 2 (OH) 3 +3H 2 ↑

[0006] These reactions will cause the surface of aluminum powder to darken, thus affecting the appearance of the paint film. At the same time, hydrogen will be produced during the reaction, causing the pressure in the packaging barrel to increase and expand, which will lead to safety accidents. Therefore, aluminum pigments used in water-based inks must be surface treated to prevent them from reacting with water in the system and ensure the stability of the water-based ink.

[0007] The existing aluminum pigments for water-based inks mainly use aluminum pigments with a D50 of about 10μm or less. Due to their very small particle size, their surface area per unit mass is large and their surface activation energy is very high. Compared with other water-based aluminum pigments with larger particle sizes, the following problems are particularly prominent:

[0008] 1. Decorative effect of aluminum pigments for water-based inks: Due to the surface treatment, a protective layer is added to the surface of the aluminum sheet. While protecting the aluminum sheet, this protective layer will inhibit the overall hue of the aluminum pigment to a certain extent, especially in terms of metallic texture and hiding power.

[0009] 2. Stability of aluminum pigments for water-based inks: After aluminum pigments for water-based inks are made into water-based inks, some problems will occur during storage that affect their performance. Since water-based inks are weakly alkaline and contain a large amount of water, if the surface coating of aluminum pigments for water-based inks is not dense enough, the coating layer will fall off due to friction, water contact, etc., and it will react with water, causing the aluminum pigment to form paint stratification, darkening, agglomeration, and other problems.

[0010] 3. Dispersibility of aluminum pigments for water-based inks: Currently, aluminum pigments for water-based inks have poor dispersibility in water, so some auxiliary solvents (such as alcohol ether solvents) must be added to assist in dispersing aluminum pigments for water-based inks. This is mainly because the hydrophilicity of the surface of aluminum pigments for water-based inks is poor, and the surface of aluminum pigments needs to be further treated to increase hydrophilic groups to achieve the purpose of complete water-based inks. Summary of the invention

[0011] In order to solve the above technical problems, the present invention provides a method for preparing aluminum pigment for water-based ink, and the specific technical scheme is as follows:

[0012] A method for preparing aluminum pigment for water-based ink comprises the following steps:

[0013] Step 1: Select aluminum pigment A with D50 less than 15 μm and a particle size distribution span less than 1 μm, wherein the pure aluminum content in the aluminum pigment A is counted as N, and mix the aluminum pigment A with the alcohol ether solvent A at a mass ratio of m N :m 醇醚类溶剂A =1:(3-6) After mixing, disperse evenly, and then heat to (48±2)°C to obtain aluminum pigment B;

[0014] Step 2: Mix the phosphate ester and alcohol ether solvent B in a mass ratio of m 磷酸酯 :m 醇醚类溶剂B =1:(3-6) After mixing, disperse evenly to obtain solution A;

[0015] Step 3: Mix solution A at a mass ratio of m 磷酸酯 :m N =(0.01-0.1):1 is added into aluminum pigment B, and after sufficient reaction, it is filtered and dried to obtain aluminum pigment C;

[0016] Step 4: Mix aluminum pigment C and alcohol ether solvent C in a mass ratio of m N :m 醇醚类溶剂C =1:(3-6) After mixing, stirring and washing for 4 hours, filtering and drying, and sieving through a 170-230 mesh sieve after being completely dried to obtain a powdered aluminum pigment D;

[0017] Step 5: Mix the powdered aluminum pigment D and the alcohol ether solvent D in a mass ratio of m N :m 醇醚类溶剂D=1:(3-6) After mixing, disperse evenly, then heat to 40°C, add acidic regulator, adjust pH to 5-6, and obtain intermediate product, according to mass ratio m 中间产物中醇醚类溶剂总量 :m 去离子水A =1: (0.01-0.1) add deionized water A, let stand for 4 hours, and after complete reaction, obtain aluminum pigment E;

[0018] Step 6: Heat the aluminum pigment E to 60°C and add N :m 硅烷偶联剂 =1:(0.01-0.1) add silane coupling agent diluent, and after complete reaction, obtain aluminum pigment F, wherein the silane coupling agent diluent is a product obtained by mixing an amino-containing silane coupling agent and an alcohol ether solvent E in a mass ratio of 1:(8-12);

[0019] Step 7: Add deionized water B at a mass ratio of m 去离子水B :m 铝颜料F中醇醚类溶剂总量 = (0.01 ~ 0.1): 1 added to aluminum pigment F, then added alkaline regulator, adjusted pH to 8 ~ 9, according to the mass ratio m N :m 正硅酸乙酯 =1: (0.01-0.1) add ethyl orthosilicate, and after complete reaction, sieve through a 170-230 mesh sieve, filter and dry to obtain powdered aluminum pigment G;

[0020] Step 8: Mix aluminum pigment G and phosphate-modified water-based resin in a mass ratio of m N :m 磷酸酯改性的水性树脂

[0021] =1:(0.01-0.05) mixing, kneading and dispersing to obtain a solid aluminum pigment product, or fusing and dispersing to obtain a liquid aluminum pigment product.

[0022] Preferably,

[0023] The kneading and dispersing specifically comprises the following steps:

[0024] Step 11: mixing the aluminum pigment G and the phosphate-modified water-based resin and kneading them for 0.5 h to obtain the aluminum pigment H;

[0025] Step 12: Heat the aluminum pigment H to 70°C and add the aluminum pigment H according to the mass ratio m N :m 水性树脂 =1: (0.1-0.3) add water-based resin, and disperse evenly after the water-based resin is completely melted to obtain aluminum pigment I;

[0026] Step 13: After the aluminum pigment I is formed and dried, the aluminum pigment solid product is obtained;

[0027] The fusion dispersion specifically comprises the following steps:

[0028] Step 21: placing the aluminum pigment G in a vacuum drying oven, baking at 100° C. until the volatile content is less than 1%, and then sieving through a 170-230 mesh sieve to obtain a powdered aluminum pigment J;

[0029] Step 22: The powdered aluminum pigment J and solution B are mixed and dispersed evenly, and the alcohol ether solvent is continued to be added to obtain the liquid aluminum pigment product, wherein the solution B is a mixture of a phosphate-modified water-based resin and an alcohol ether solvent F in a mass ratio of 1:(5-10), and the mass fraction of pure aluminum content in the liquid aluminum pigment product is (65±2)%.

[0030] Preferably, the dispersion method in step 1, step 2, step 5, step 12 and step 22 is stirring dispersion, wherein the stirring time in step 12 is 0.5 h.

[0031] Preferably,

[0032] The solution A in step 3 is added dropwise for 1 hour, and then allowed to stand for 4 hours to allow for complete reaction;

[0033] The silane coupling agent dilution solution in step 6 is added dropwise for 1 hour, and then allowed to stand at 60° C. for 4 hours to allow for complete reaction;

[0034] The method of adding ethyl orthosilicate in step 7 is dropwise addition, and the dropwise addition process is divided into two times, and a single dropwise addition process lasts for 2 hours. After each dropwise addition, the mixture is allowed to stand for 4 hours to allow for complete reaction.

[0035] Preferably,

[0036] The filtering and drying method in step 3 is to filter through a filter press and then blow dry;

[0037] The filtration and drying method in step 4 is to filter through a filter press and then blow dry, and then put it into a drying oven and dry it at 80°C;

[0038] The filtering and drying method in step 7 is to filter through a filter press and then blow dry;

[0039] The drying method in step 13 is to place the mixture in a vacuum drying oven and dry it at 50°C.

[0040] Preferably,

[0041] In step 5, the acidic regulator is a mixed solution of hydrochloric acid and an alcohol ether solvent;

[0042] In step 7, the alkaline regulator is a mixed solution of ammonia water and an alcohol ether solvent.

[0043] Preferably, the 170-230 mesh sieve in step 4, step 7 and step 21 is specifically a 200 mesh sieve.

[0044] Preferably,

[0045] The phosphate ester in step 2 is an alkyl phosphate ester;

[0046] The phosphate-modified water-based resin in step 8 is a phosphate-modified water-based acrylic resin or a phosphate-modified water-based amino resin;

[0047] The water-based resin in step 12 is a water-based acrylic resin or a water-based polyurethane resin.

[0048] Preferably, the preparation method of the phosphate-modified waterborne acrylic resin specifically comprises the following steps:

[0049] Step 31: Mix acrylate, phosphate and alcohol ether solvent G in a mass ratio of 1:(0.8-1):(8-10) and disperse them uniformly, and heat to 100° C. to obtain solution C;

[0050] Step 32: Add the initiator at a mass ratio m 引发剂 :m 溶液C =1:(35-40) added to solution C, stirred and dispersed evenly;

[0051] Step 33: Cooling to 50-60° C., adding an alkaline regulator, adjusting the pH to 7.5-8.5, and dispersing evenly to obtain the phosphate-modified waterborne acrylic resin.

[0052] Preferably, the alkaline regulator in step 33 is a mixed solution of dimethylethanolamine and an alcohol ether solvent.

[0053] The method for preparing aluminum pigment for water-based ink provided in this embodiment has the following beneficial effects:

[0054] 1. Through the surface passivation of phosphate ester, the surface activation energy of fine-particle aluminum pigment is reduced, thereby reducing the reaction rate of subsequent silicon coating, ensuring the density of silicon coating, and reducing the loss of aluminum pigment hue;

[0055] 2. The introduction of an amino-containing silane coupling agent as an intermediate substance enables the phosphate ester in the first coating layer to react with the amino group in the silane coupling agent after hydrolysis, and then the silane coupling agent is hydrolyzed again and continues to react with the hydrolysis product of ethyl orthosilicate, thereby achieving the purpose of coating a silicon coating layer outside the phosphate coating layer;

[0056] 3. A phosphate-modified water-based resin is introduced as a connection between a silicon coating layer and the water-based ink system, so that the produced aluminum pigment can be better dispersed in the water-based ink. DETAILED DESCRIPTION

[0057] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below. The description in this section is only exemplary and explanatory and should not have any limiting effect on the scope of protection of the present invention.

[0058] The present invention provides a method for preparing aluminum pigment for water-based ink, comprising the following steps:

[0059] Step 1: Select aluminum pigment A with D50 less than 15 μm and a particle size distribution span less than 1 μm, wherein the pure aluminum content in the aluminum pigment A is counted as N, and mix the aluminum pigment A with the alcohol ether solvent A at a mass ratio of m N :m 醇醚类溶剂A =1:(3~6) and dispersed evenly after mixing, and then heated to (48±2)°C to obtain aluminum pigment B.

[0060] Step 2: Mix the phosphate ester and alcohol ether solvent B in a mass ratio of m 磷酸酯 :m 醇醚类溶剂B =1:(3~6) and disperse evenly after mixing to obtain solution A.

[0061] Step 3: Mix solution A at a mass ratio of m 磷酸酯 :m N =(0.01~0.1):1 is added into aluminum pigment B, and after sufficient reaction, it is filtered and dried to obtain aluminum pigment C.

[0062] Step 4: Mix aluminum pigment C and alcohol ether solvent C in a mass ratio of m N :m 醇醚类溶剂C =1:(3-6) After mixing, stir and wash for 4 hours, filter and dry, and after being completely dried, sieve through a 170-230 mesh sieve to obtain powdered aluminum pigment D.

[0063] Step 5: Mix the powdered aluminum pigment D and the alcohol ether solvent D in a mass ratio of m N :m 醇醚类溶剂D =1:(3-6) After mixing, disperse evenly, then heat to 40°C, add acidic regulator, adjust pH to 5-6, and obtain intermediate product, according to mass ratio m 中间产物中醇醚类溶剂总量 :m 去离子水A =1:(0.01~0.1) Add deionized water A, let stand for 4 hours, and obtain aluminum pigment E after complete reaction.

[0064] Step 6: Heat the aluminum pigment E to 60°C and add N :m 硅烷偶联剂 =1:(0.01-0.1) add silane coupling agent diluent, and after complete reaction, obtain aluminum pigment F, wherein the silane coupling agent diluent is a product obtained by mixing an amino-containing silane coupling agent and an alcohol ether solvent E in a mass ratio of 1:(8-12).

[0065] Step 7: Add deionized water B at a mass ratio of m 去离子水B :m 铝颜料F中醇醚类溶剂总量 = (0.01 ~ 0.1): 1 added to aluminum pigment F, then added alkaline regulator, adjusted pH to 8 ~ 9, according to the mass ratio m N :m 正硅酸乙酯 =1: (0.01-0.1) Add ethyl orthosilicate, and after complete reaction, sieve through a 170-230 mesh sieve, filter and dry to obtain powdered aluminum pigment G.

[0066] Step 8: Mix aluminum pigment G and phosphate-modified water-based resin in a mass ratio of m N :m 磷酸酯改性的水性树脂 =1:(0.01-0.05) mixing, kneading and dispersing to obtain a solid aluminum pigment product, or fusing and dispersing to obtain a liquid aluminum pigment product.

[0067] The method provided by the present invention is mainly operated in the following steps: passivation, cleaning, primary drying, surface treatment, secondary drying, and finished product manufacturing. Steps S1 to S3 are passivation operations; step S4 is cleaning and primary drying operations; steps S5 to S7 are surface treatment and secondary drying operations; and step S8 is a finished product manufacturing operation.

[0068] In the passivation operation of steps S1 to S3, a phosphate coating layer is formed on the surface of the aluminum pigment. During the coating process, the entire system environment is neutral and the coating layer is a single molecule thick. Therefore, after the first layer of coating, the hue of the aluminum pigment will not be affected. The protective layer not only has a certain protective effect on the aluminum sheet, but also can prevent the acid and alkali corrosion of the aluminum sheet in the subsequent process, resulting in loss of hue. More importantly, the protective layer has a certain inhibitory effect on the excessively high surface activation energy of fine-particle aluminum pigments, preventing the subsequent coating from being too fast and the coating layer from being not dense enough, resulting in increased loss of hue of the aluminum pigment.

[0069] In the surface treatment operation of steps S5 to S7, a silicon coating layer is formed on the surface of the aluminum pigment, and this protective layer is the main protective layer. In this embodiment, the silane coupling agent dilution and ethyl orthosilicate can be added by slow dripping for multiple times to reduce the reaction rate and increase the density of the silicon coating layer. While ensuring that the protective effect remains unchanged, the thickness of the coating layer is reduced as much as possible, thereby reducing the hue loss of the aluminum pigment.

[0070] In the finished product manufacturing operation of step S8, a phosphate-modified water-based resin coating is formed on the surface of the aluminum pigment. Since the "P-OH" in the phosphate-modified water-based resin coating reacts with the "Si-OH" in the outer layer of the second layer to generate "Si-OP", the phosphate groups are facing inward toward the aluminum sheet to protect the aluminum sheet from corrosion. The water-based resin facing outward has a high hydrophilic property, which makes the aluminum pigment well and evenly dispersed in the water-based ink.

[0071] The method for preparing aluminum pigment for water-based ink provided in this embodiment has the following beneficial effects:

[0072] 1. Through the surface passivation of phosphate ester, the surface activation energy of fine-particle aluminum pigment is reduced, thereby reducing the reaction rate of subsequent silicon coating, ensuring the density of silicon coating, and reducing the loss of aluminum pigment hue.

[0073] 2. The introduction of an intermediate substance, an amino-containing silane coupling agent, enables the phosphate ester in the first coating layer to react with the amino group in the silane coupling agent after hydrolysis, and then the silane coupling agent is hydrolyzed again and continues to react with the hydrolysis product of ethyl orthosilicate, thereby achieving the purpose of coating a layer of silicon coating outside the phosphate coating layer.

[0074] 3. A phosphate-modified water-based resin is introduced as a connection between a silicon coating layer and the water-based ink system, so that the produced aluminum pigment can be better dispersed in the water-based ink.

[0075] Furthermore, in the examples provided in this embodiment:

[0076] Kneading and dispersing specifically includes the following steps:

[0077] Step 11: Aluminum pigment G and phosphate-modified water-based resin are mixed and kneaded for 0.5 h to obtain aluminum pigment H.

[0078] Step 12: Heat the aluminum pigment H to 70°C and add the aluminum pigment H according to the mass ratio m N :m 水性树脂 =1:(0.1-0.3) Add water-based resin, and disperse evenly after the water-based resin is completely melted to obtain aluminum pigment I.

[0079] Step 13: After the aluminum pigment I is formed and dried, a solid aluminum pigment product is obtained.

[0080] Fusion dispersion specifically includes the following steps:

[0081] Step 21: Place the aluminum pigment G in a vacuum drying oven and bake it at 100° C. until the volatile content is less than 1%, and then sieve it through a 170-230 mesh sieve to obtain a powdered aluminum pigment J.

[0082] Step 22: The powdered aluminum pigment J and solution B are mixed and dispersed evenly, and an alcohol ether solvent is added to obtain a liquid aluminum pigment product, wherein the solution B is a mixture of a phosphate-modified water-based resin and an alcohol ether solvent F in a mass ratio of 1:(5-10), and the mass fraction of pure aluminum content in the liquid aluminum pigment product is (65±2)%.

[0083] Furthermore, the dispersion method in step 1, step 2, step 5, step 12 and step 22 is stirring dispersion, wherein the stirring time in step 12 is 0.5h.

[0084] Furthermore, in the examples provided in this embodiment:

[0085] In step 3, solution A is added dropwise for 1 hour, and the solution is allowed to stand for 4 hours after the addition to allow for complete reaction.

[0086] In step 6, the silane coupling agent dilution solution is added dropwise for 1 hour, and then allowed to stand at 60° C. for 4 hours to allow for complete reaction.

[0087] In step 7, ethyl orthosilicate is added dropwise in two steps, each step lasts for 2 hours, and each step is allowed to stand for 4 hours to allow for complete reaction.

[0088] Furthermore, in the examples provided in this embodiment:

[0089] The filtering and drying method in step 3 is to filter through a filter press and then blow dry.

[0090] The filtering and drying method in step 4 is to filter through a filter press and then blow dry, and then put it into a drying oven and dry it at 80°C.

[0091] The filtering and drying method in step 7 is to filter through a filter press and then blow dry.

[0092] The drying method in step 13 is to place the mixture in a vacuum drying oven and dry it at 50°C.

[0093] Furthermore, in the examples provided in this embodiment:

[0094] In step 5, the acidic regulator is a mixed solution of hydrochloric acid and an alcohol ether solvent.

[0095] In step 7, the alkaline regulator is a mixed solution of ammonia water and an alcohol ether solvent.

[0096] Furthermore, in the examples provided in this embodiment: the 170-230 mesh sieve in step 4, step 7 and step 21 is specifically a 200 mesh sieve.

[0097] Furthermore, in the examples provided in this embodiment:

[0098] In step 2, the phosphate ester is an alkyl phosphate ester.

[0099] The phosphate-modified water-based resin in step 8 is a phosphate-modified water-based acrylic resin or a phosphate-modified water-based amino resin.

[0100] In step 12, the water-based resin is a water-based acrylic resin or a water-based polyurethane resin.

[0101] Furthermore, the preparation method of the phosphate-modified waterborne acrylic resin specifically comprises the following steps:

[0102] Step 31: Mix acrylate, phosphate and alcohol ether solvent G in a mass ratio of 1:(0.8-1):(8-10) and disperse them evenly, and heat to 100° C. to obtain solution C.

[0103] Step 32: Add the initiator at a mass ratio m 引发剂 :m 溶液C =1:(35~40) added to solution C, stirred and dispersed evenly.

[0104] Step 33: Cool down to 50-60° C., then add an alkaline regulator to adjust the pH to 7.5-8.5, and disperse evenly to obtain a phosphate-modified waterborne acrylic resin.

[0105] Furthermore, in step 33, the alkaline regulator is a mixed solution of dimethylethanolamine and an alcohol ether solvent.

[0106] Two specific embodiments are provided below, and the embodiments provided can enable those skilled in the art to more fully understand the present invention, but do not limit the present invention in any way. In the following embodiments, the alcohol ether solvent is preferably a mixed solvent of propylene glycol butyl ether and n-butanol, and its mass ratio is 1:4.

[0107] Embodiment 1:

[0108] Measure 100g of aluminum silver powder with a D50 of 15μm, a particle size distribution span of less than 1μm, a strong metallic texture and good covering power, of which the pure aluminum content accounts for 95%, and add it into a stirring tank with 500g of an alcohol ether solvent. After stirring and dispersing evenly, raise the system temperature to 48°C and maintain it, then mix and disperse 5g of alkyl phosphate ester with 25g of an alcohol ether solvent and add it dropwise for 1 hour. After the addition is completed, keep the reaction for 4 hours. After reacting for 4 hours, filter it through a filter press and blow it dry.

[0109] 500 g of alcohol ether solvent was added to the stirring tank, stirred and washed for 4 hours, and then filtered through a filter press and dried.

[0110] Place in a drying oven, dry completely at 80°C, and then sieve through a 200-mesh sieve.

[0111] Put it into a stirring tank and add 500g of alcohol ether solvent. After stirring and dispersing evenly, heat it to 40°C, add hydrochloric acid diluted with alcohol ether solvent, adjust the pH of the solution system to 6, add 30g of deionized water, and react for 4 hours.

[0112] The temperature was raised to 60° C., 5 g of an amino-containing silane coupling agent was mixed with 45 g of an alcohol ether solvent and then added dropwise for 1 hour, and the mixture was reacted at a constant temperature of 60° C. for 4 hours.

[0113] 20 g of deionized water was added again, and ammonia diluted with an alcohol ether solvent was added to adjust the pH of the system to 8. Then 5 g of ethyl orthosilicate was added dropwise in two portions, each time for 2 hours and then reacted for 4 hours. After the reaction, the mixture was sieved through a 200-mesh sieve, filtered with a filter press, and dried.

[0114] The mixture was added to a kneader and 3 g of a phosphate-modified water-based acrylic resin was added, and the kneading was continued for 30 minutes.

[0115] Raise the temperature to 70°C, add 10g of water-based acrylic resin, and after the water-based acrylic resin is completely melted, continue stirring for half an hour until it is evenly stirred. Then, extrude the mixture into strips, put it into a vacuum drying oven, and dry it at 50°C to obtain aluminum pigment for water-based ink.

[0116] Embodiment 2:

[0117] Measure 100g of aluminum silver powder with a D50 of 15μm, a particle size distribution span of less than 1μm, a strong metallic texture and good covering power, of which the pure aluminum content accounts for 95%, and add it into a stirring tank with 500g of an alcohol ether solvent. After stirring and dispersing evenly, raise the system temperature to 48°C and maintain it, then mix and disperse 5g of alkyl phosphate ester with 25g of an alcohol ether solvent and add it dropwise for 1 hour. After the addition is completed, keep the reaction for 4 hours. After reacting for 4 hours, filter it through a filter press and blow it dry.

[0118] 500 g of alcohol ether solvent was added to the stirring tank, stirred and washed for 4 hours, and then filtered through a filter press and dried.

[0119] Place in a drying oven, dry completely at 80°C, and then sieve through a 200-mesh sieve.

[0120] Put it into a stirring tank and add 500g of alcohol ether solvent. After stirring and dispersing evenly, heat it to 40°C, add hydrochloric acid diluted with alcohol ether solvent, adjust the pH of the solution system to 6, add 30g of deionized water, and react for 4 hours.

[0121] The temperature was raised to 60° C., 5 g of an amino-containing silane coupling agent was mixed with 45 g of an alcohol ether solvent and then added dropwise for 1 hour, and the mixture was reacted at a constant temperature of 60° C. for 4 hours.

[0122] 20 g of deionized water was added again, and ammonia diluted with an alcohol ether solvent was added to adjust the pH of the system to 8. Then 5 g of ethyl orthosilicate was added dropwise in two portions, each time for 2 hours and then reacted for 4 hours. After the reaction, the mixture was sieved through a 200-mesh sieve, filtered with a filter press, and dried.

[0123] The mixture was placed in a vacuum drying oven and baked at 100°C until the non-volatile matter content was 99%, and then sieved through a 200-mesh sieve.

[0124] 3 g of phosphate-modified water-based acrylic resin and 20 g of alcohol ether solvent were mixed and added, and then 60 g of alcohol ether solvent was added to obtain aluminum pigment for water-based ink.

[0125] Working principle:

[0126] In the passivation operation of steps S1 to S3, a phosphate coating layer is formed on the surface of the aluminum pigment. During the coating process, the entire system environment is neutral, and the coating layer is a single molecule thick. Therefore, after the first coating, the hue of the aluminum pigment will not be affected. The protective layer not only has a certain protective effect on the aluminum sheet, but also can prevent the acid and alkali from corroding the aluminum sheet in the subsequent process and causing the loss of hue. More importantly, the protective layer has a certain inhibitory effect on the excessively high surface activation energy of the fine-particle aluminum pigment, preventing the subsequent coating from being too fast and the coating layer from being not dense enough, resulting in an increase in the loss of hue of the aluminum pigment.

[0127] In the surface treatment operation of steps S5 to S7, a silicon coating layer is formed on the surface of the aluminum pigment, and the protective layer is the main protective layer. In this embodiment, the silane coupling agent dilution and ethyl orthosilicate can be added by slow dripping for multiple times to reduce the reaction rate and increase the density of the silicon coating layer. While ensuring that the protective effect remains unchanged, the coating layer thickness is reduced as much as possible, thereby reducing the hue loss of the aluminum pigment.

[0128] In the finished product manufacturing operation of step S8, a phosphate-modified water-based resin coating is formed on the surface of the aluminum pigment. Since the "P-OH" in the phosphate-modified water-based resin coating reacts with the "Si-OH" in the outer layer of the second layer to generate "Si-OP", the phosphate groups are facing inward toward the aluminum sheet to protect the aluminum sheet from corrosion. The water-based resin facing outward has a high hydrophilic property, which makes the aluminum pigment well and evenly dispersed in the water-based ink.

[0129] The principles and implementation methods of the present invention are described herein using specific examples, and the description of the above embodiments is only used to help understand the method and core ideas of the present invention. The above are only preferred implementations of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention, which should be within the protection scope of the present invention.

Claims

1. A method for preparing aluminum pigment for water-based ink, characterized in that: The steps include: S1: Select aluminum pigment A with D50 less than 15 μm and a particle size distribution span less than 1 μm, wherein the pure aluminum content in the aluminum pigment A is N, and mix the aluminum pigment A with the alcohol ether solvent A at a mass ratio of m N :m 醇醚类溶剂A =1:(3-6) After mixing, disperse evenly, and then heat to (48±2)°C to obtain aluminum pigment B; S2: Mix phosphate ester and alcohol ether solvent B in a mass ratio of m 磷酸酯 :m 醇醚类溶剂B =1:(3-6) After mixing, disperse evenly to obtain solution A; S3: Solution A is mixed at a mass ratio of m 磷酸酯 :m N =(0.01-0.1):1 is added into aluminum pigment B, and after sufficient reaction, it is filtered and dried to obtain aluminum pigment C; S4: Mix aluminum pigment C and alcohol ether solvent C in a mass ratio of m N :m 醇醚类溶剂C =1:(3-6) After mixing, stirring and washing for 4 hours, filtering and drying, and sieving through a 170-230 mesh sieve after being completely dried to obtain a powdered aluminum pigment D; S5: Powdered aluminum pigment D and alcohol ether solvent D are mixed in a mass ratio of m N :m 醇醚类溶剂D =1:(3-6) After mixing, disperse evenly, then heat to 40°C, add acidic regulator, adjust pH to 5-6, and obtain intermediate product, according to mass ratio m 中间产物中醇醚类溶剂总量 :m 去离子水A =1: (0.01-0.1) add deionized water A, let stand for 4 hours, and after complete reaction, obtain aluminum pigment E; S6: Heat the aluminum pigment E to 60°C and add the aluminum pigment E at a mass ratio of m N :m 硅烷偶联剂 =1:(0.01-0.1) add silane coupling agent diluent, and after complete reaction, obtain aluminum pigment F, wherein the silane coupling agent diluent is a product obtained by mixing an amino-containing silane coupling agent and an alcohol ether solvent E in a mass ratio of 1:(8-12); S7: Deionized water B is added at a mass ratio m 去离子水B :m 铝颜料F中醇醚类溶剂总量 = (0.01 ~ 0.1): 1 added to aluminum pigment F, then added alkaline regulator, adjusted pH to 8 ~ 9, according to the mass ratio m N :m 正硅酸乙酯 =1: (0.01-0.1) add ethyl orthosilicate, and after complete reaction, sieve through a 170-230 mesh sieve, filter and dry to obtain powdered aluminum pigment G; S8: Aluminum pigment G and phosphate modified waterborne resin are mixed in a mass ratio of m N :m 磷酸酯改性的水性树脂 =1:(0.01-0.05) mixing, kneading and dispersing to obtain a solid aluminum pigment product, or fusing and dispersing to obtain a liquid aluminum pigment product.

2. The method according to claim 1, characterized in that: The kneading and dispersing specifically comprises the following steps: S11: mixing aluminum pigment G and a phosphate-modified water-based resin and kneading them for 0.5 h to obtain aluminum pigment H; S12: Heat the aluminum pigment H to 70°C and add the aluminum pigment H according to the mass ratio m N :m 水性树脂 =1: (0.1-0.3) add water-based resin, and disperse evenly after the water-based resin is completely melted to obtain aluminum pigment I; S13: After the aluminum pigment I is formed and dried, the aluminum pigment solid product is obtained; The fusion dispersion specifically comprises the following steps: S21: placing the aluminum pigment G in a vacuum drying oven, baking at 100° C. until the volatile content is less than 1%, and then sieving through a 170-230 mesh sieve to obtain a powdered aluminum pigment J; S22: The powdered aluminum pigment J and solution B are mixed and dispersed evenly, and an alcohol ether solvent is added to obtain the aluminum pigment liquid product, wherein the solution B is a mixture of a phosphate-modified water-based resin and an alcohol ether solvent F in a mass ratio of 1:(5-10), and the mass fraction of pure aluminum content in the aluminum pigment liquid product is (65±2)%.

3. The method according to claim 2, characterized in that The dispersion method in steps S1, S2, S5, S12 and S22 is stirring dispersion, wherein the stirring time in step S12 is 0.5h.

4. The method according to claim 1, characterized in that: The solution A in step S3 is added dropwise for 1 hour, and then left to stand for 4 hours to allow for complete reaction; The silane coupling agent dilution solution in step S6 is added dropwise for 1 hour, and then allowed to stand at 60° C. for 4 hours to allow for complete reaction. The method of adding ethyl orthosilicate in step S7 is dropwise addition, and the dropwise addition process is divided into two times, and a single dropwise addition process lasts for 2 hours. After each dropwise addition, the mixture is left to stand for 4 hours to allow for complete reaction.

5. The method according to claim 2, characterized in that: The filtering and drying method in step S3 is to filter by a filter press and then blow dry; The filtration and drying method in step S4 is to filter through a filter press and then blow dry, and then put it into a drying oven and dry it at 80°C; The filtering and drying method in step S7 is to filter by a filter press and then blow dry; The drying method in step S13 is to place the product in a vacuum drying oven and dry it at 50°C.

6. The method according to claim 1, characterized in that: In step S5, the acidic regulator is a mixed solution of hydrochloric acid and an alcohol ether solvent; In step S7, the alkaline regulator is a mixed solution of ammonia water and an alcohol ether solvent.

7. The method according to claim 2, characterized in that In steps S4, S7 and S21, the 170-230 mesh screen is specifically a 200 mesh screen.

8. The method according to claim 2, characterized in that: The phosphate ester in step S2 is an alkyl phosphate ester; The phosphate-modified water-based resin in step S8 is a phosphate-modified water-based acrylic resin or a phosphate-modified water-based amino resin; The water-based resin in step S12 is a water-based acrylic resin or a water-based polyurethane resin.

9. The method according to claim 8, characterized in that The preparation method of the phosphate-modified waterborne acrylic resin specifically comprises the following steps: S31: Mix acrylate, phosphate and alcohol ether solvent G in a mass ratio of 1:(0.8-1):(8-10) and disperse them uniformly, and heat to 100° C. to obtain solution C; S32: The initiator is mixed according to the mass ratio m 引发剂 :m 溶液C =1:(35-40) added to solution C, stirred and dispersed evenly; S33: cooling to 50-60° C., adding an alkaline regulator, adjusting the pH to 7.5-8.5, and dispersing evenly to obtain the phosphate-modified waterborne acrylic resin.

10. The method according to claim 9, characterized in that In step S33, the alkaline regulator is a mixed solution of dimethylethanolamine and an alcohol ether solvent.