Ink-jet printing ink formula and preparation method thereof

Abstract

The invention relates to an ink-jet printing ink formula and a preparation method thereof, and belongs to the technical field of ink preparation. The carbon black color paste specifically comprises the following raw materials in parts by mass: 3 to 7 parts of carboxylated carbon black, 2 to 4 parts of modified protein, 1 to 3 parts of a dispersant, 0.1 to 0.3 part of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, 0.1 to 0.12 part of N-hydroxysuccinimide, 1 to 5 parts of a 2-morpholinoethanesulfonic acid buffer solution, 0.1 to 0.3 part of an auxiliary agent and 10 to 50 parts of a composite solvent. The polyethylene glycol modified ethanol clostridium protein is used in the components, and carboxylated carbon black and the dispersing agent are combined, so that the compatibility among the components in the system is improved, and good thermal stability and system stability are achieved while the particle size of the black ink is refined.

Description

Technical Field

[0001] The present application relates to the technical field of ink preparation, and more specifically, to an inkjet printing ink formulation and a preparation method thereof. Background Art

[0002] In inkjet printing technology, the stability and dispersion of ink are directly related to the printing quality and the maintenance cost of the equipment. Traditional inkjet printing ink formulations often face many challenges during long-term storage and use. The components in the ink, such as pigments, resins, surfactants, etc., are prone to precipitation after standing for a long time, resulting in a significant decrease in the stability and dispersion of the ink system. This not only affects the smoothness of the ink jetting, but also easily clogs the print head, causing equipment failure and increased maintenance costs.

[0003] In addition, the viscosity change in some areas of the ink system is also a major problem. Due to the uneven precipitation and distribution of each component, the viscosity of the ink will vary significantly in different areas, which in turn affects the formation of ink droplets and the accuracy of jetting. This will not only lead to a decrease in the clarity of the printed image, but may also cause quality problems such as uneven color and blurred lines. Especially when printing black text, black printing ink requires smaller pigment particle size, higher color density and saturation to ensure that the printed text or image is clear, sharp, and uniform in black. However, as the particle size decreases, the interaction force between the particles will weaken, causing the pigment particles to settle and precipitate more easily, resulting in liquid stratification or pigment aggregation at the bottom, reducing the stability of the system.

[0004] Therefore, developing an inkjet printing ink formulation and a preparation method thereof with excellent stability and dispersion effect has become the key to solving the above technical problems. Summary of the invention

[0005] The object of the present invention is to provide an inkjet printing ink formula and a preparation method thereof to solve the problems raised in the background technology. By optimizing the composition ratio of the ink, improving the preparation process and adding an appropriate amount of stabilizer and dispersant, the long-term stability and dispersion effect of the ink can be effectively improved, ensuring that the ink maintains uniformity and fluidity during storage and use, thereby improving the printing quality and reliability of the equipment. Polyethylene glycol-modified ethanol clostridial protein is used in the formula and carboxylated carbon black and dispersant are combined to improve the compatibility between the components in the system, and while refining the particle size of the black ink, good thermal stability and system stability are achieved.

[0006] To achieve the above object, the present invention provides the following technical solutions: An inkjet printing ink formulation comprises the following raw materials in parts by weight: 3-7 parts of carboxylated carbon black, 2-4 parts of modified protein, 1-3 parts of dispersant, 0.1-0.3 parts of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, 0.1-0.12 parts of N-hydroxysuccinimide, 1-5 parts of 2-morpholineethanesulfonic acid buffer, 0.1-0.3 parts of auxiliary agent and 10-50 parts of composite solvent; Wherein, the dispersant is polyethyleneimine or triethylamine; The modified protein is obtained by mixing the protein and activated polyethylene glycol in a buffer; The composite solvent is obtained by mixing sterile deionized water and an organic solvent, and the organic solvent is at least one of alcohol, ether, ketone and ester solvents.

[0007] Furthermore, the auxiliary agent is at least one of methyl parahydroxybenzoate, polydimethylsilicone, an antioxidant, and polyacrylate.

[0008] In the above formula, the solvent of the ink is a mixture of sterile deionized water and organic solvent, which reduces the use of harmful solvents and improves the environmental performance of the ink. The addition of additives such as methyl paraben and antioxidants can enhance the anti-oxidation and anti-ultraviolet properties of the ink, so that the printed image can remain bright and clear for a long time and is not easy to fade or age.

[0009] Further, carboxylated carbon black is prepared by following steps: Add carbon black to sterile deionized water and perform ultrasonic treatment for 10-30 minutes to obtain a carbon black suspension; then add a carboxyl derivative and a sulfuric acid solution to the carbon black suspension, stir at 80-100°C for 4-6 hours, then cool to room temperature and filter the system, collect the precipitate and wash it with sterile deionized water until the pH value of the washing solution is neutral, dry the precipitate until constant weight, and then treat it at 300-500°C and inert atmosphere for 1-2 hours to obtain carboxylated carbon black.

[0010] Further, carboxylated carbon black is prepared by following steps: Carbon black is added to sterile deionized water at a mass volume ratio of 1g:5mL, and ultrasonically treated at an ultrasonic power of 100-200W for 10-30 minutes at room temperature to obtain a carbon black suspension; then a carboxyl derivative and a 65-75wt% sulfuric acid solution are added to the carbon black suspension, stirred at 80-100°C for 4-6 hours, then cooled to room temperature and the system is filtered, the precipitate is collected and washed with sterile deionized water until the pH value of the washing solution is neutral, the precipitate is vacuum dried at 60-80°C until constant weight, and then placed at 300-500°C and treated under inert atmosphere for 1-2 hours to obtain carboxylated carbon black.

[0011] Furthermore, the mass volume ratio of carbon black, carboxyl derivative and sulfuric acid solution is 10 g:(20-30) g:(5-10) mL.

[0012] Furthermore, the carboxyl derivative is at least one of a carboxylic acid substance and a carboxylic anhydride substance. The carboxylic acid substance is at least one of a saturated monobasic acid, an unsaturated carboxylic acid, a fatty acid, and an aromatic acid. The carboxylic anhydride substance is at least one of acetic anhydride, propionic anhydride, and benzoic anhydride.

[0013] Further, the modified protein is prepared by the following steps: A1. Add an ester reagent, polyethylene glycol and triethylamine to an organic solvent, stir at 15-25° C. for 12-36 hours, filter and retain the filtrate, recrystallize the filtrate, filter again after crystallization, dialyze the system, and then freeze-dry to obtain activated polyethylene glycol; A2. Add the protein and the activated polyethylene glycol prepared in step A1 into a borate buffer, stir the system at room temperature for 12-36 hours, and then dialyze to obtain the modified protein.

[0014] Further, the modified protein is prepared by the following steps: A1. Add an ester reagent, polyethylene glycol and triethylamine to an organic solvent, stir at 15-25° C. for 12-36 hours, filter and retain the filtrate, recrystallize the filtrate, filter again after crystallization, dialyze the system at a pH of 6 and a cutoff of 1500 Da, and then freeze-dry to obtain activated polyethylene glycol; A2. Add the protein and the activated polyethylene glycol prepared in step A1 into a 0.1 mol / L borate buffer with a pH value of 9.4, stir the system at room temperature for 24 hours, and then dialyze using a membrane with a molecular cutoff of 25,000 Da and sterile deionized water to obtain the modified protein.

[0015] In the above reaction process, the hydroxyl group on the polyethylene glycol reacts with the ester reagent to generate an ester substance, and then the ester substance forms an amide bond with the amino group on the protein molecule, thereby preparing a modified protein.

[0016] Furthermore, in step A1, the ester reagent is at least one of diisopropyl carbonate, dihydroxymethane sulfonate and N-hydroxysuccinimide ester.

[0017] Furthermore, in step A2, the protein used is Clostridium ethanolicum protein.

[0018] Furthermore, in step A2, the mass volume ratio of protein, activated polyethylene glycol and borate buffer is 100 mg:(400-800) mg:5 mL.

[0019] A method for preparing an inkjet printing ink comprises the following steps: S1, mixing the carboxylated carbon black, dispersant, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide and 2-morpholineethanesulfonic acid buffer in the formula weight for 12-36 hours at room temperature and inert atmosphere to obtain a base ink; S2. Then, the composite solvent, the additive and the modified protein are added to the base ink obtained in step S1, and the mixture is sheared for 30-60 minutes. Then, the system is ultrasonically treated for 10-30 minutes, and the ultrasonically treated system is degassed for 10-30 minutes and filtered to obtain an inkjet printing ink.

[0020] In the above reaction process, the carboxyl groups of the carboxylated carbon black and the amino groups on the dispersant generate amide bonds under the action of (3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide. The 2-morpholineethanesulfonic acid buffer provides an environment for the reaction and, as a component of the ink, can improve the stability of the modified protein in the ink.

[0021] Further, a method for preparing an inkjet printing ink comprises the following preparation steps: S1. Mixing carboxylated carbon black, dispersant, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide and 2-morpholineethanesulfonic acid buffer at a speed of 30-90 rpm for 12-36 hours at room temperature and inert atmosphere to obtain a base ink; In the above reaction process, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide are used as coupling agent and carboxyl activator respectively, so that the carboxyl group on the carboxylated carbon black reacts with the amino group on the dispersant to form an amide bond, which contains the same functional group as the modified protein, so that the systems have good compatibility.

[0022] S2. Then, the composite solvent, additive and modified protein are added to the base ink obtained in step S1, and the mixture is mixed and sheared for 30-60 minutes, the rotation speed is set to 2000-4000 rpm, and the system is then ultrasonically treated, the power is set to 100-200 W, and the treatment time is 10-30 minutes. The ultrasonically treated system is then placed in a vacuum degasser for degassing for 10-30 minutes, and filtered using a 0.2 μm filter to obtain an inkjet printing ink.

[0023] In summary, this application has the following beneficial effects: In the technical solution of the present invention, carboxyl functional groups are introduced into the surface of carbon black through the preparation process of carboxylated carbon black, which enhances the dispersibility and stability of carbon black in water, reduces the agglomeration and precipitation of carbon black during the use of ink, and thus improves the printing effect and stability of ink. The use of carboxylated carbon black increases the blackness and color saturation of ink, making the printed image clearer, sharper, and more colorful.

[0024] The addition of dispersant further promotes the uniform dispersion of carbon black in the ink, reduces the interaction between particles, and maintains the long-term stability of the ink. At the same time, modified protein is introduced into the formula. Polyethylene glycol with good biocompatibility is used in the preparation process of the modified protein. PEG is a high molecular compound with good water solubility. By modifying the ethanol clostridium protein with PEG, the hydrophilicity of the protein can be increased, so that it is easier to dissolve and disperse in aqueous media. In addition, the ethanol clostridium protein and polyethylene glycol have anti-precipitation and anti-agglomeration properties, which can prevent the aggregation and agglomeration of pigments or other components in the ink, improve the stability of the ethanol clostridium protein in the ink, prevent it from aggregation, precipitation or denaturation during storage and use, and ensure the long-term stability of the ink and the consistency of the printing effect. At the same time, the molecular weight and concentration of PEG can adjust the viscosity of the ink to a certain extent, making it more in line with the requirements of inkjet printers, and improving the physical properties of the ink such as surface tension, viscosity, and thermal stability. Appropriate viscosity can ensure that the ink flows smoothly during the printing process, so that the ink can better control the formation and injection of ink droplets during the inkjet printing process, reduce the risk of nozzle clogging, and improve the printing accuracy and consistency, which promotes the application of ink in fields such as bioprinting or food packaging.

[0025] The preparation methods of carboxylated carbon black and modified protein are relatively simple, the raw materials are readily available, the operating conditions are mild, and they are suitable for industrial production. By using N-hydroxysuccinimide and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, carboxylated carbon black is combined with the amino group on the dispersant to form an amide bond, which has good compatibility with the modified protein in the system. The system is then treated by mixing, shearing, ultrasound, and degassing to obtain high-quality inkjet printing ink. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] The carbon black used in the following examples and comparative examples is pigment carbon black C166, with a particle size of 7-19 nm and a reflectivity of 25%.

[0028] The alcoholic Clostridium protein used was provided by Beijing Shoulang Biotechnology Co., Ltd., with a protein content of ≥80%; Example 1 An inkjet printing ink formulation comprises the following raw materials in parts by weight: 3 parts of carboxylated carbon black, 2 parts of modified protein, 1 part of dispersant, 0.1 parts of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, 0.1 parts of N-hydroxysuccinimide, 1 part of 2-morpholineethanesulfonic acid buffer, 0.1 parts of auxiliary agent and 10 parts of composite solvent; Wherein, the concentration of 2-morpholineethanesulfonic acid buffer is 0.1 mol / L; The composite solvent is obtained by mixing diethylene glycol, propylene glycol and diethylene glycol butyl ether in a volume ratio of 7:7:4; The dispersant used was polyethyleneimine; The auxiliary agent used is antioxidant 1010.

[0029] Wherein, carboxylated carbon black is prepared by following steps: 10 g of carbon black was added to sterile deionized water at a mass volume ratio of 1 g:5 mL, and ultrasonically treated at an ultrasonic power of 100 W for 10 minutes at room temperature to obtain a carbon black suspension; then 20 g of a carboxyl derivative and 5 mL of a 65 wt% sulfuric acid solution were added to the carbon black suspension, stirred at 80° C. at a rate of 30 rpm for 4 hours, then cooled to room temperature and the system was filtered, the precipitate was collected and washed with sterile deionized water until the pH value of the washing solution was neutral, the precipitate was vacuum dried at 60° C. until constant weight, and then placed at 300° C. and treated in a nitrogen atmosphere for 1 hour to obtain carboxylated carbon black; The carboxyl derivative used was acetic acid.

[0030] Wherein, the modified protein is prepared by the following steps: A1. Add 0.3 g of an ester reagent, 2.5 g of polyethylene glycol-2000 and 0.2 g of triethylamine to 50 mL of acetonitrile, stir at 15 ° C for 12 hours, filter and retain the filtrate, add 500 ml of ether to the filtrate, let stand overnight at 0 ° C, filter again after crystallization, dialyze the system under the conditions of pH 6 and a cutoff of 1500 Da, and then freeze-dry to obtain activated polyethylene glycol; A2, adding 100 mg of protein and 400 mg of activated polyethylene glycol prepared in step A1 to 5 mL of 0.1 mol / L borate buffer with a pH value of 9.4, stirring the system at room temperature for 24 hours, and then dialyzing using a membrane with a molecular cutoff of 25000 Da and sterile deionized water to obtain a modified protein; The ester reagent used was dihydroxymethanesulfonate; The protein used is Clostridium alcoholicum protein.

[0031] A method for preparing an inkjet printing ink comprises the following steps: S1, mixing carboxylated carbon black, dispersant, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide and 2-morpholineethanesulfonic acid buffer at room temperature and nitrogen atmosphere at a speed of 30 rpm for 12 hours to obtain a base ink; S2. Then, the composite solvent, additive and modified protein are added to the base ink obtained in step S1, and the mixture is mixed and sheared for 30 minutes. The rotation speed is set to 2000 rpm. Then, the system is ultrasonically treated with a power of 100 W for 10 minutes. The ultrasonically treated system is then placed in a vacuum degasser for degassing for 10 minutes, and filtered using a 0.2 μm filter to obtain an inkjet printing ink.

[0032] Example 2 An inkjet printing ink formulation comprises the following raw materials in parts by weight: 5 parts of carboxylated carbon black, 3 parts of modified protein, 2 parts of dispersant, 0.2 parts of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, 0.11 parts of N-hydroxysuccinimide, 3 parts of 2-morpholineethanesulfonic acid buffer, 0.2 parts of auxiliary agent and 30 parts of composite solvent; Wherein, the concentration of 2-morpholineethanesulfonic acid buffer is 0.1 mol / L; The composite solvent is obtained by mixing diethylene glycol, ethylene glycol and diethylene glycol butyl ether in a volume ratio of 7:7:4; The dispersant used was polyethyleneimine; The auxiliary agent used is antioxidant 1010.

[0033] Wherein, carboxylated carbon black is prepared by following steps: 10 g of carbon black was added to sterile deionized water at a mass volume ratio of 1 g:5 mL, and ultrasonically treated at an ultrasonic power of 150 W for 20 minutes at room temperature to obtain a carbon black suspension; then 25 g of a carboxyl derivative and 8 mL of a 70 wt% sulfuric acid solution were added to the carbon black suspension, stirred at 90° C. at a rate of 30 rpm for 5 hours, then cooled to room temperature and the system was filtered, the precipitate was collected and washed with sterile deionized water until the pH value of the washing solution was neutral, the precipitate was vacuum dried at 80° C. until constant weight, and then placed at 400° C. and treated in a nitrogen atmosphere for 1.5 hours to obtain carboxylated carbon black; The carboxyl derivative used was acetic acid.

[0034] Wherein, the modified protein is prepared by the following steps: A1. Add 0.6 g of an ester reagent, 5 g of polyethylene glycol-2000 and 0.29 g of triethylamine to 50 mL of acetonitrile, stir at 21° C. for 24 hours, filter and retain the filtrate, add 500 ml of ether to the filtrate, let stand overnight at 4° C., filter again after crystallization, dialyze the system at a pH of 6 and a cutoff of 1500 Da, and then freeze-dry to obtain activated polyethylene glycol; A2, adding 100 mg of protein and 600 mg of activated polyethylene glycol prepared in step A1 to 5 mL of 0.1 mol / L borate buffer with a pH value of 9.4, stirring the system at room temperature for 24 hours, and then dialyzing using a membrane with a molecular cutoff of 25000 Da and sterile deionized water to obtain a modified protein; The ester reagent used was dihydroxymethanesulfonate; The protein used is Clostridium alcoholicum protein.

[0035] A method for preparing an inkjet printing ink comprises the following steps: S1, mixing the carboxylated carbon black, dispersant, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide and 2-morpholineethanesulfonic acid buffer at room temperature and nitrogen atmosphere at a speed of 60 rpm for 24 hours to obtain a base ink; S2. Then, the composite solvent, additive and modified protein are added to the base ink obtained in step S1, and the mixture is mixed and sheared for 45 minutes. The rotation speed is set to 3000 rpm. Then, the system is ultrasonically treated with a power of 150 W for 20 minutes. The ultrasonically treated system is then placed in a vacuum degasser for degassing for 20 minutes, and filtered using a 0.2 μm filter to obtain an inkjet printing ink.

[0036] Example 3 An inkjet printing ink formulation comprises the following raw materials in parts by weight: 7 parts of carboxylated carbon black, 4 parts of modified protein, 3 parts of dispersant, 0.3 parts of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, 0.12 parts of N-hydroxysuccinimide, 5 parts of 2-morpholineethanesulfonic acid buffer, 0.3 parts of auxiliary agent and 50 parts of composite solvent; Wherein, the concentration of 2-morpholineethanesulfonic acid buffer is 0.1 mol / L.

[0037] The composite solvent is obtained by mixing diethylene glycol, propylene glycol and diethylene glycol butyl ether in a volume ratio of 7:7:4; The dispersant used was triethylamine; The auxiliary agent used is polydimethylsilicone oil.

[0038] Wherein, carboxylated carbon black is prepared by following steps: 10 g of carbon black was added to sterile deionized water at a mass volume ratio of 1 g:5 mL, and ultrasonically treated at an ultrasonic power of 200 W for 30 minutes at room temperature to obtain a carbon black suspension; then 30 g of a carboxyl derivative and 10 mL of a 75 wt% sulfuric acid solution were added to the carbon black suspension, stirred at 100 ° C at a rate of 30 rpm for 6 hours, then cooled to room temperature and the system was filtered, the precipitate was collected and washed with sterile deionized water until the pH value of the washing solution was neutral, the precipitate was vacuum dried at 80 ° C until constant weight, and then placed at 500 ° C and nitrogen atmosphere for 2 hours to obtain carboxylated carbon black; The carboxyl derivative used was acetic anhydride.

[0039] Wherein, the modified protein is prepared by the following steps: A1. Add 0.9 g of an ester reagent, 7.5 g of polyethylene glycol-2000 and 0.4 g of triethylamine to 50 mL of acetonitrile, stir at 25 ° C for 36 hours, filter and retain the filtrate, add 500 ml of ether to the filtrate, let stand overnight at 4 ° C, filter again after crystallization, dialyze the system under the conditions of pH 6 and a cutoff of 1500 Da, and then freeze-dry to obtain activated polyethylene glycol; A2, 100 mg of protein and 800 mg of activated polyethylene glycol prepared in step A1 were added to 5 mL of 0.1 mol / L borate buffer with a pH value of 9.4, and the system was stirred at room temperature for 24 hours, and then dialyzed using a membrane with a molecular cutoff of 25000 Da and sterile deionized water to obtain a modified protein; The ester reagent used was diisopropyl carbonate; The protein used is Clostridium alcoholicum protein.

[0040] A method for preparing an inkjet printing ink comprises the following steps: S1, mixing carboxylated carbon black, dispersant, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide and 2-morpholineethanesulfonic acid buffer at room temperature and nitrogen atmosphere at a speed of 90 rpm for 36 hours to obtain a base ink; S2. Then, the composite solvent, additive and modified protein are added to the base ink obtained in step S1, and the mixture is mixed and sheared for 60 minutes. The rotation speed is set to 4000 rpm. Then, the system is ultrasonically treated with a power of 200 W for 30 minutes. The ultrasonically treated system is placed in a vacuum degasser for degassing for 30 minutes, and filtered using a 0.2 μm filter to obtain an inkjet printing ink.

[0041] Comparative Example 1 The difference between this comparative example and Example 1 is that in this comparative example, the modified protein is prepared by the following steps: 100 mg of protein and 400 mg of polyethylene glycol-2000 were added to 5 mL of 0.1 mol / L borate buffer with a pH value of 9.4, and the system was stirred at room temperature for 24 hours, and then dialyzed using a membrane with a molecular cutoff of 25000 Da and sterile deionized water to obtain the modified protein; The ester reagent used was dihydroxymethanesulfonate; The protein used is Clostridium alcoholicum protein.

[0042] Comparative Example 2 The difference between this comparative example and Example 1 is that in this comparative example, the ethanolic Clostridium protein is replaced by soy protein isolate; wherein the content of the soy protein isolate is ≥95%.

[0043] Comparative Example 3 The difference between this comparative example and Example 1 is that in this comparative example, carbon black is used instead of carboxylated carbon black.

[0044] Comparative Example 4 The difference between this comparative example and Example 1 is that an inkjet printing ink formulation comprises the following raw materials in parts by weight: 3 parts of carboxylated carbon black, 2 parts of modified protein, 1 part of dispersant, 0.2 parts of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, 1 part of 2-morpholineethanesulfonic acid buffer, 0.1 parts of auxiliary agent and 10 parts of composite solvent; A method for preparing an inkjet printing ink comprises the following steps: S1, mixing the carboxylated carbon black, dispersant, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 2-morpholineethanesulfonic acid buffer at room temperature and nitrogen atmosphere at a speed of 30 rpm for 12 hours to obtain a base ink; S2. Then, the composite solvent, additive and modified protein are added to the base ink obtained in step S1, and the mixture is mixed and sheared for 30 minutes. The rotation speed is set to 2000 rpm. Then, the system is ultrasonically treated with a power of 100 W for 10 minutes. The ultrasonically treated system is then placed in a vacuum degasser for degassing for 10 minutes, and filtered using a 0.2 μm filter to obtain an inkjet printing ink.

[0045] Comparative Example 5 The difference between this comparative example and Example 1 is that an inkjet printing ink formulation comprises the following raw materials in parts by weight: 3 parts of carboxylated carbon black, 2 parts of ethanolic clostridial protein, 1 part of dispersant, 0.1 parts of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, 0.1 parts of N-hydroxysuccinimide, 1 part of 2-morpholineethanesulfonic acid buffer, 0.1 parts of auxiliary agent and 10 parts of composite solvent; A method for preparing an inkjet printing ink comprises the following steps: S1, mixing carboxylated carbon black, dispersant, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide and 2-morpholineethanesulfonic acid buffer at room temperature and nitrogen atmosphere at a speed of 30 rpm for 12 hours to obtain a base ink; S2. Then, the composite solvent, ethanol clostridial protein and auxiliary agent are added to the base ink obtained in step S1, and the mixture is mixed and sheared for 30 minutes. The rotation speed is set to 2000 rpm. Then, the system is ultrasonically treated with a power of 100 W for 10 minutes. The ultrasonically treated system is placed in a vacuum degasser for degassing for 10 minutes, and filtered using a 0.2 μm filter to obtain an inkjet printing ink.

[0046] Performance Testing The physical and chemical properties of the inkjet printing inks prepared in Examples 1-3 and Comparative Examples 1-5 are now tested. The viscosity and surface tension of the ink samples prepared in different groups are tested.

[0047] Viscosity: The viscosity of the sample was tested using a rotational viscometer according to the standard in ASTM D445; Surface tension: The surface tension of the sample was tested using a pendant drop tensiometer according to ASTM D1331.

[0048] Each sample was tested 5 times and the average value was recorded. The specific performance test results are shown in Table 1: Table 1 Physical and chemical properties of the inkjet printing inks prepared in Examples 1-3 and Comparative Examples 1-5

[0049] From the results shown in Table 1 above, it can be seen that the viscosity (7-8 cSt) and surface tension (30-36 dyne / cm) of the inkjet printing ink prepared in the three embodiments are moderate, meeting the operating requirements of the inkjet system.

[0050] The inkjet printing inks prepared in Examples 1-3 and Comparative Examples 1-5 are now tested for stability. The inkjet printing inks prepared in different groups are kept in a constant temperature oven at 40°C for one week, and the system changes of the samples are observed to determine the thermal stability of the inks. The samples in different groups are centrifuged in a centrifuge at 3000 rpm for 30 minutes, and then filtered to observe whether there are stratifications and precipitates to determine the system stability of the inks. The test results are shown in Table 2.

[0051] The criteria for judging stability are: Grade A: The system has no stratification or agglomeration, and the viscosity variation range is ≤5%; Grade B: The system has no stratification, slight coagulation, and the viscosity variation range is ≤7%; Grade C: The system has no stratification, but agglomeration occurs, and the viscosity variation range is ≤10%; Grade D: The system is stratified and coagulated, and the viscosity changes by >10%.

[0052] Table 2 Stability test of inkjet printing ink prepared in Examples 1-3 and Comparative Examples 1-5

[0053] It can be seen from the results in Table 2 that the inks prepared in Examples 1-3 have good thermal stability and system stability. It can be seen from the results in Comparative Examples 1, 3 and 4 that the use of polyethylene glycol to modify ethanolic clostridial protein has good compatibility with the structure formed by the dispersant and carboxylated carbon black in the system, and the stability is increased while the components in the system are uniformly dispersed. It can be seen from the results in Comparative Example 2 that the use of ethanolic clostridial protein and polyethylene glycol in combination has a better effect on improving the stability of inkjet printing inks than other types of proteins. Combining the data in Tables 1 and 2 in Comparative Example 4, it can be seen that due to the poor stability of the system in Comparative Example 4, when testing the viscosity and surface tension of the system, although the values ​​are moderate, the effect is not good during the actual printing process.

[0054] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0055] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. An inkjet printing ink formulation, characterized in that: Including the following raw materials by weight: 3-7 parts of carboxylated carbon black, 2-4 parts of modified protein, 1-3 parts of dispersant, 0.1-0.3 parts of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, 0.1-0.12 parts of N-hydroxysuccinimide, 1-5 parts of 2-morpholineethanesulfonic acid buffer, 0.1-0.3 parts of auxiliary agent and 10-50 parts of composite solvent; Wherein, the dispersant is polyethyleneimine or triethylamine; The modified protein is obtained by mixing the protein and activated polyethylene glycol in a buffer; The composite solvent is obtained by mixing sterile deionized water and an organic solvent, and the organic solvent is at least one of alcohol, ether, ketone and ester solvents.

2. An inkjet printing ink formulation according to claim 1, characterized in that: The auxiliary agent is at least one of methyl parahydroxybenzoate, polydimethyl silicone oil, an antioxidant and polyacrylate.

3. An inkjet printing ink formulation according to claim 1, characterized in that: Described carboxylated carbon black is prepared by following steps: Add carbon black to sterile deionized water and perform ultrasonic treatment for 10-30 minutes to obtain a carbon black suspension; then add a carboxyl derivative and a sulfuric acid solution to the carbon black suspension, stir at 80-100°C for 4-6 hours, then cool to room temperature and filter the system, collect the precipitate and wash it with sterile deionized water until the pH value of the washing solution is neutral, dry the precipitate until constant weight, and then treat it at 300-500°C and inert atmosphere for 1-2 hours to obtain carboxylated carbon black.

4. An inkjet printing ink formulation according to claim 3, characterized in that: The mass volume ratio of carbon black, carboxyl derivative and sulfuric acid solution is 10g:(20-30)g:(5-10)mL.

5. An inkjet printing ink formulation according to claim 3, characterized in that: The carboxyl derivative is at least one of a carboxylic acid substance and a carboxylic anhydride substance.

6. An inkjet printing ink formulation according to claim 1, characterized in that: The modified protein is prepared by the following steps: A1. Add an ester reagent, polyethylene glycol and triethylamine to an organic solvent, stir at 15-25° C. for 12-36 hours, filter and retain the filtrate, recrystallize the filtrate, filter again after crystallization, dialyze the system, and then freeze-dry to obtain activated polyethylene glycol; A2. Add the protein and the activated polyethylene glycol prepared in step A1 into a borate buffer, stir the system at room temperature for 12-36 hours, and then dialyze to obtain the modified protein.

7. An inkjet printing ink formulation according to claim 6, characterized in that: In step A1, the ester reagent is at least one of diisopropyl carbonate, dihydroxymethyl sulfonate and N-hydroxysuccinimide ester.

8. An inkjet printing ink formulation according to claim 6, characterized in that: In step A2, the protein is Clostridium ethanolicum protein.

9. An inkjet printing ink formulation according to claim 6, characterized in that: In step A2, the mass volume ratio of protein, activated polyethylene glycol and borate buffer is 100 mg:(400-800) mg:5 mL.

10. A method for preparing an inkjet printing ink as claimed in any one of claims 1 to 9, characterized in that: The method comprises the following preparation steps: S1, mixing the carboxylated carbon black, dispersant, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide and 2-morpholineethanesulfonic acid buffer in the formula weight for 12-36 hours at room temperature and inert atmosphere to obtain a base ink; S2. Then, the composite solvent, the additive and the modified protein are added to the base ink obtained in step S1, and the mixture is sheared for 30-60 minutes. Then, the system is ultrasonically treated for 10-30 minutes, and the ultrasonically treated system is degassed for 10-30 minutes and filtered to obtain an inkjet printing ink.

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