Digital direct-injection ink

Abstract

The invention discloses digital direct-injection ink which comprises the following components in percentage by mass: 20%-40% of pigment color paste, 1%-5% of a surfactant, 10%-20% of waterborne polyurethane resin, 3%-10% of polyurethane acrylate dispersion, 5%-15% of fatty alcohol-polyoxyethylene ether, 5%-20% of a humectant and the balance of water, wherein the waterborne polyurethane resin is prepared from the following raw materials in parts by weight: 12 to 20 parts of polyester polyol / polyether polyol, 5 to 10 parts of diisocyanate, 0.5 to 1.5 parts of 2, 2-dimethylolpropionic acid, 0.1 to 1 part of micromolecular polyol, 0.001 to 0.01 part of a catalyst, 15 to 25 parts of acetone, 0.5 to 1 part of a neutralizing agent, 45 to 60 parts of water and 0.3 to 1.5 parts of an amine chain extender. The digital direct-injection ink disclosed by the invention is good in stability, better in washing fastness, relatively uniform in ink particle size, not easy to agglomerate into large particles, better in printing fluency and higher in production efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of digital printing, and in particular to a digital direct-jet ink. Background Art

[0002] At present, the traditional and more mature process for printing on cotton cloth is active ink printing. This ink has the best printing effect, beautiful and bright colors, and very good color fastness. At the same time, it will not affect the original feel of the cloth. However, the active ink printing process is relatively complicated, requiring a series of processes such as sizing-drying-printing-steaming-washing-drying. Since many processes involve the use of water, and the amount of water used is also large, the pollution is also large. Therefore, the investment in active ink printing is very large, and it is not suitable for small-scale operations. It is obviously not satisfied with the personalized customization needs of the current young consumer groups. Digital direct injection ink solves these problems very well. The investment is not large, the process is simple and the pollution is small, which is especially suitable for small-scale personalized customization. However, the digital direct injection ink prepared by the existing water-based polyurethane resin has certain problems in stability, water fastness and printing fluency. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a digital direct-jet ink, which has high stability and good water washing fastness. At the same time, the ink particle size is relatively uniform and is not easy to agglomerate into large particles. The printing fluency is better and the production efficiency is higher.

[0004] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0005] The first aspect of the present invention provides a digital direct-jet ink, comprising the following components by mass percentage: 20% to 40% of pigment paste, 1% to 5% of surfactant, 10% to 20% of waterborne polyurethane resin, 3% to 10% of polyurethane acrylate dispersion, 5% to 15% of fatty alcohol polyoxyethylene ether, 5% to 20% of moisturizer, and the balance of water;

[0006] The waterborne polyurethane resin is prepared from the following raw materials in parts by weight: 12-20 parts of polyester polyol / polyether polyol, 5-10 parts of diisocyanate, 0.5-1.5 parts of 2,2-dihydroxymethylpropionic acid, 0.1-1 parts of small molecule polyol, 0.001-0.01 parts of catalyst, 15-25 parts of acetone, 0.5-1 parts of neutralizer, 45-60 parts of water, and 0.3-1.5 parts of amine chain extender.

[0007] Furthermore, the moisturizing agent is one or more of ethylene glycol, polyethylene glycol, diethylene glycol, propylene glycol and glycerol.

[0008] Furthermore, the surfactant is a nonionic surfactant, and the nonionic surfactant is at least one of Surfynol 465 and Surfynol 485.

[0009] In some embodiments of the present invention, the digital direct-jet ink includes the following components by mass percentage: 20% pigment paste, 2% surfactant, 15% water-based polyurethane resin, 5% polyurethane acrylate dispersion, 12% fatty alcohol polyoxyethylene ether, 15% humectant, and the balance water.

[0010] Furthermore, the preparation method of the waterborne polyurethane resin comprises the following steps:

[0011] S1. The polyester polyol / polyether polyol is mixed with diisocyanate and reacted at 86 to 88°C for 1 to 3 hours to obtain material A;

[0012] S2. After the material A is cooled, a small molecule polyol is added and reacted at 80 to 88° C. for 0.1 to 1 hour to obtain material B;

[0013] S3. After the material B is cooled, 2,2-dimethylol propionic acid, a catalyst and acetone are added in sequence, and the reaction is continued at 60 to 70 ° C for 2 to 5 hours to obtain a polyurethane prepolymer;

[0014] S4. The polyurethane prepolymer is cooled to 45 to 50°C, a neutralizing agent is added for neutralization reaction; water is then added for emulsification, an amine chain extender is added, and the reaction is stirred to obtain material C;

[0015] S5. distill material C under reduced pressure at 45-55° C. to obtain the water-based polyurethane resin for digital direct-jet ink.

[0016] In step S1 of the present invention, since the polyester polyol / polyether polyol is easily absorbed by trace moisture in the air when exposed to the air, and the moisture will consume isocyanate in the later polymerization reaction, which will have an adverse effect on the formulation and product performance, the polyester polyol / polyether polyol is preferably dehydrated before the reaction.

[0017] In some preferred embodiments of the present invention, the dehydration treatment method is: heating the polyester polyol / polyether polyol to 100-105° C. and dehydrating under vacuum for 1-2 hours.

[0018] In step S1 of the present invention, the molecular weight M of the polyester polyol / polyether polyol is n It is preferably between 1000 and 2000, for example, 1000, 1500, 2000, etc., but is not limited to the listed values, and other unlisted values ​​or ranges within the numerical range are also applicable.

[0019] In step S1 of the present invention, the polyester polyol / polyether polyol may be a polyol commonly used in the synthesis of polyurethane resin, including but not limited to at least one of polyhexanediol adipate diol, polyhexanediol adipate neopentyl glycol ester diol, polyneopentyl adipate diol, polycaprolactone diol, and polycarbonate diol.

[0020] In step S1 of the present invention, the diisocyanate may be an isocyanate component commonly used in the synthesis of polyurethane resins, including but not limited to at least one of isophorone diisocyanate and dicyclohexylmethane diisocyanate.

[0021] In step S1 of the present invention, the reaction temperature is 86-88°C.

[0022] In step S2 of the present invention, the small molecule polyol may be a small molecule polyol commonly used in the synthesis process of polyurethane resin, including but not limited to at least one of butanediol, hexanediol, neopentyl glycol, and diethylene glycol.

[0023] In step S2 of the present invention, the reaction temperature is 80-88°C.

[0024] In step S3 of the present invention, the role of acetone is to reduce the viscosity of the system. The catalyst may be a catalyst commonly used in the synthesis of polyurethane resins, including but not limited to at least one of an organic bismuth catalyst and an organic zinc catalyst.

[0025] In step S3 of the present invention, the reaction temperature is 60-70° C., and the reaction time is 2-5 hours.

[0026] In step S4 of the present invention, the neutralizing agent may be a commonly used alkaline substance, including but not limited to at least one of triethylamine and sodium hydroxide. The neutralization reaction time may be 3 to 5 minutes.

[0027] In step S4 of the present invention, when water is added for emulsification, it is preferably carried out under high-speed stirring conditions, and preferably low-temperature (0-10°C) deionized water is used. After the emulsification is completed, an amine chain extender is added, and the amine chain extender can be various small molecule amine substances, including but not limited to at least one of ethylenediamine and hexamethylenediamine. Preferably, ethylenediamine diluted with ice water is added after the emulsification is completed, and the mixture is stirred and left to stand overnight. The purpose of adding ice water is to reduce the concentration of the system.

[0028] In step S5 of the present invention, the purpose of using reduced pressure distillation is to evaporate the residual acetone in the system. The temperature of reduced pressure distillation is 45-55°C.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The digital direct-jet ink provided by the present invention can improve the stability of the ink and the permeability to the polyester-cotton material by adding a specific aqueous polyurethane resin, as well as a polyurethane acrylate dispersion and a fatty alcohol polyoxyethylene ether. The hot-stamped pattern is not only clear, but also has high adhesion and better water fastness.

[0031] 2. The digital direct-jet ink provided by the present invention has a relatively uniform particle size, is not easy to agglomerate into large particles, has better printing fluency, and has higher production efficiency. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a 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 those skilled in the art without creative work are within the scope of protection of the present invention.

[0033] Preparation Example 1

[0034] 135 parts of polyhexanediol adipate (Mn=2000) were vacuumed and dehydrated at 105-110°C and 0.09MPa for 1 hour. 55.6 parts of isophorone diisocyanate were added, stirred and kept at 86°C for 2 hours. 4.8 parts of hexanediol were added and kept at 86°C for 0.5 hours. 130 parts of acetone, 8.1 parts of dimethylol propionic acid and 0.06 parts of catalyst were added, and the temperature was kept at 65-70°C for 3.5 hours. 6 parts of triethylamine neutralizer were added for neutralization. After 2.5 minutes, 470 parts of water were added for emulsification at a dispersing machine speed of 1100r / min, and the speed was maintained for dispersion; 3.4 parts of ethylenediamine were added to 28 parts of water and stirred evenly, and slowly added to the emulsion, and stirring was continued for 40 minutes. The emulsion was stirred for 2 h at 54° C. and 0.09 MPa vacuum conditions to remove the solvent acetone, thereby obtaining a water-based polyurethane resin for digital direct-jet ink.

[0035] Preparation Example 2

[0036] 135 parts of polyhexanediol adipate neopentyl glycol ester diol (Mn = 2000) were vacuumed and dehydrated at 105-110°C and 0.09MPa for 1 hour. 65.1 parts of dicyclohexylmethane diisocyanate were added, stirred and kept at 86°C for 2 hours. 3.6 parts of butanediol were added, kept at 86°C for 0.5 hours. 130 parts of acetone, 8.1 parts of dimethylol propionic acid and 0.06 parts of catalyst were added, kept at 65-70°C for 3.5 hours. 6 parts of triethylamine neutralizer were added for neutralization. After 2.5 minutes, 490 parts of water were added at a dispersing machine speed of 1100r / min for emulsification, and the speed was maintained for dispersion; 3.4 parts of ethylenediamine were added to 28 parts of water and stirred evenly, slowly added to the emulsion, and continued to stir for 40 minutes. The emulsion was stirred for 2 h at 54° C. and 0.09 MPa vacuum conditions to remove the solvent acetone, thereby obtaining a water-based polyurethane resin for digital direct-jet ink.

[0037] Preparation Example 3

[0038] 67.5 parts of poly(neopentyl adipate glycol) (Mn=2000) and 67.5 parts of poly(caprolactone glycol) (Mn=2000) were vacuumed and dehydrated at 105-110°C and 0.09 MPa for 1 hour. 27.8 parts of isophorone diisocyanate and 32.6 parts of dicyclohexylmethane diisocyanate were added, stirred and kept at 86°C for 2 hours. 3.6 parts of butanediol were added, kept at 86°C for 0.5 hours. 130 parts of acetone, 8.1 parts of dimethylol propionic acid and 0.06 parts of catalyst were added, kept at 65-70°C for 3.5 hours. Add 6 parts of triethylamine neutralizer for neutralization. After 2.5 minutes, add 460 parts of water for emulsification at a dispersing machine speed of 1100r / min, and keep the speed for dispersion; add 6.6 parts of hexamethylenediamine to 54 parts of water and stir evenly, slowly add to the emulsion, and continue stirring for 40 minutes. Keep stirring the emulsion at 54°C and 0.09MPa vacuum for 2 hours, remove the solvent acetone, and obtain the water-based polyurethane resin for digital direct-injection ink.

[0039] Preparation Example 4

[0040] 90 parts of poly(neopentyl adipate glycol) (Mn=2000) and 45 parts of polycarbonate diol (Mn=1000) were vacuumed and dehydrated at 105-110°C and 0.09MPa for 1 hour. 55.6 parts of isophorone diisocyanate were added, stirred and kept at 86°C for 2 hours. 2.1 parts of hexanediol were added, kept at 86°C for 0.5 hours. 130 parts of acetone, 8.1 parts of dimethylol propionic acid and 0.06 parts of catalyst were added, kept at 65-70°C for 3.5 hours. 6 parts of triethylamine neutralizer were added for neutralization. After 2.5 minutes, 460 parts of water were added at a dispersing machine speed of 1100r / min for emulsification, and the speed was maintained for dispersion; 3.4 parts of ethylenediamine were added to 28 parts of water and stirred evenly, slowly added to the emulsion, and continued to stir for 40 minutes. The emulsion was stirred for 2 h at 54° C. and 0.09 MPa vacuum conditions to remove the solvent acetone, thereby obtaining a water-based polyurethane resin for digital direct-jet ink.

[0041] Preparation Example 5

[0042] 45 parts of polyhexanediol adipate (Mn=1000) and 90 parts of polycaprolactone diol (Mn=2000) were vacuumed and dehydrated at 105-110°C and 0.09MPa for 1 hour. 27.8 parts of isophorone diisocyanate and 32.6 parts of dicyclohexylmethane diisocyanate were added, stirred and kept at 86°C for 2 hours. 1.6 parts of butanediol were added and kept at 86°C for 0.5 hours. 130 parts of acetone, 8.1 parts of dimethylolpropionic acid and 0.06 parts of catalyst were added, and the temperature was kept at 65-70°C for 3.5 hours. 6 parts of triethylamine neutralizer were added for neutralization. After 2.5 minutes, 450 parts of water were added at a dispersing machine speed of 1100r / min for emulsification, and the speed was maintained for dispersion; 6.6 parts of hexamethylenediamine were added to 54 parts of water and stirred evenly, and slowly added to the emulsion, and stirring was continued for 40 minutes. The emulsion was stirred for 2 h at 54° C. and 0.09 MPa vacuum conditions to remove the solvent acetone, thereby obtaining a water-based polyurethane resin for digital direct-jet ink.

[0043] Example 1

[0044] The present embodiment provides a digital direct-jet ink, comprising the following components by mass fraction: 15% of the aqueous polyurethane resin of Preparation Example 1, 20% of the Pigment Red 122 color paste, 2% of the Surfynol 465 surfactant, 10% of propylene glycol, 5% of diethylene glycol, 5% of WPU-063 aliphatic polyurethane acrylate dispersion, 12% of fatty alcohol polyoxyethylene ether, and the remainder being deionized water.

[0045] Under stirring conditions, pigment paste, propylene glycol, diethylene glycol and other components are added to deionized water in sequence, stirred and mixed evenly, and then filtered through a 0.45 μm microporous filter membrane to obtain a digital direct-injection ink.

[0046] Example 2

[0047] This embodiment provides a digital direct-injection ink, and its preparation method is the same as that of Example 1. The formula of the digital direct-injection ink is: 10% of the aqueous polyurethane resin of Preparation Example 2, 20% of the pigment red 122 color paste, 4% of Surfynol 465 surfactant, 12% of glycerol, 2% of diethylene glycol, 5% of WPU-063 aliphatic polyurethane acrylate dispersion, 15% of fatty alcohol polyoxyethylene ether, and the rest is deionized water.

[0048] Example 3

[0049] This embodiment provides a digital direct-injection ink, and its preparation method is the same as that of Example 1. The formula of the digital direct-injection ink is: 18% of the aqueous polyurethane resin of Preparation Example 3, 25% of the pigment red 122 color paste, 2% of Surfynol 465 surfactant, 10% of propylene glycol, 2% of diethylene glycol, 4% of WPU-063 aliphatic polyurethane acrylate dispersion, 12% of fatty alcohol polyoxyethylene ether, and the rest is deionized water.

[0050] Example 4

[0051] This embodiment provides a digital direct-injection ink, and its preparation method is the same as that of Example 1. The formula of the digital direct-injection ink is: 12% of the aqueous polyurethane resin of Preparation Example 4, 28% of the pigment red 122 color paste, 1% of Surfynol 465 surfactant, 16% of propylene glycol, 6% of WPU-063 aliphatic polyurethane acrylate dispersion, 8% of fatty alcohol polyoxyethylene ether, and the rest is deionized water.

[0052] Example 5

[0053] This embodiment provides a digital direct-injection ink, and its preparation method is the same as that of Example 1. The formula of the digital direct-injection ink is: 18% of the aqueous polyurethane resin of Preparation Example 5, 30% of the pigment red 122 color paste, 4% of Surfynol 465 surfactant, 10% of propylene glycol, 6% of diethylene glycol, 5% of WPU-063 aliphatic polyurethane acrylate dispersion, 12% of fatty alcohol polyoxyethylene ether, and the rest is deionized water.

[0054] Comparative Example 1

[0055] This comparative example provides a digital direct-jet ink, and its preparation method is the same as that of Example 1. The formula of the digital direct-jet ink is: 20% of the aqueous polyurethane resin of Preparation Example 1, 20% of the pigment red 122 color paste, 2% of Surfynol 465 surfactant, 10% of propylene glycol, 5% of diethylene glycol, 12% of fatty alcohol polyoxyethylene ether, and the rest is deionized water.

[0056] Comparative Example 2

[0057] This comparative example provides a digital direct-jet ink, and its preparation method is the same as that of Example 1. The formula of the digital direct-jet ink is: 15% of the aqueous polyurethane resin of Preparation Example 1, 20% of the pigment red 122 color paste, 2% of Surfynol 465 surfactant, 10% of propylene glycol, 5% of diethylene glycol, 5% of WPU-063 aliphatic polyurethane acrylate dispersion, and the rest is deionized water.

[0058] Comparative Example 3

[0059] This comparative example provides a digital direct-injection ink, and its preparation method is the same as that of Example 1. The formula of the digital direct-injection ink is: 15% of commercially available 6110 water-based polyurethane resin, 20% of Pigment Red 122 color paste, 2% of Surfynol 465 surfactant, 10% of propylene glycol, 5% of diethylene glycol, 5% of WPU-063 aliphatic polyurethane acrylate dispersion, 12% of fatty alcohol polyoxyethylene ether, and the rest is deionized water.

[0060] Comparative Example 4

[0061] This comparative example provides a digital direct-jet ink, and its preparation method is the same as that of Example 1. The formula of the digital direct-jet ink is: 5% of the aqueous polyurethane resin of Preparation Example 1, 20% of the pigment red 122 color paste, 2% of Surfynol 465 surfactant, 10% of propylene glycol, 5% of diethylene glycol, 15% of WPU-063 aliphatic polyurethane acrylate dispersion, 12% of fatty alcohol polyoxyethylene ether, and the rest is deionized water.

[0062] Test Case

[0063] Experimental Method 1: Fluency Test

[0064] Load the prepared digital direct-jet ink sample into the printer, clean the nozzle before printing to ensure that there is no broken needle or thread during printing. Under the same printing conditions, print continuously on the printing material for 1-2 hours, and print test strips at intervals as needed. If there is no broken needle or thread or a small amount of broken needle, it means that the direct-jet ink has good fluidity.

[0065] Experimental method 2: Standby test

[0066] After the digital direct jet ink completes the continuous printing task, clean the nozzle and moisturize it. After standing by for 3 hours, do the normal printing task. If no broken needles or threads are found or only a small amount of broken needles are found, it means that the 1# digital direct jet ink is ready for standby.

[0067] Experimental method 3: Stability test

[0068] The digital direct-jet ink is placed in a sealed aging test bottle and baked in a 60°C constant temperature oven for 14 days. After completion, the ink viscosity is tested and the change in ink viscosity before and after baking is compared. If the change is not significant, it means that the viscosity stability of the digital direct-jet ink after aging is acceptable. After the baking test is completed, the aged ink is loaded into the printer for a smoothness test and a standby test. If the printing is normal, it means that the digital direct-jet ink has good stability on the machine after aging.

[0069] Experimental method 4: Fastness test

[0070] The fastness test sample is completed by printing the digital direct-jet ink in the printer on the specified test sample cloth. The sample is washed and tested. If the washing test is normal, it means that the direct-jet ink fastness is acceptable.

[0071] Table 1

[0072]

[0073]

[0074] Please refer to Table 1. The digital direct-jet inks of Examples 1-5 all performed well in the fluency test, standby test, stability test and fastness test.

[0075] In Comparative Examples 1-2, when the digital direct-jet ink does not contain WPU-063 aliphatic polyurethane acrylate dispersion or fatty alcohol polyoxyethylene ether, the water fastness of the ink is significantly reduced. In Comparative Example 3, when 6110 water-based polyurethane resin is used instead of the water-washable polyurethane resin prepared by the present invention, the fluidity, stability and water fastness of the ink are reduced. In Comparative Example 4, when WPU-063 aliphatic polyurethane acrylate dispersion is added in excess, the fluidity and stability of the ink are also reduced.

[0076] In summary, the digital direct-injection ink prepared by the present invention has high stability and good water fastness. At the same time, the ink particle size is relatively uniform and is not easy to agglomerate into large particles. The printing fluency is better and the production efficiency is higher.

[0077] The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or changes made by those skilled in the art based on the present invention are within the protection scope of the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. A digital direct-injection ink, characterized in that: The invention comprises the following components by mass percentage: 20% to 40% of pigment paste, 1% to 5% of surfactant, 10% to 20% of waterborne polyurethane resin, 3% to 10% of polyurethane acrylate dispersion, 5% to 15% of fatty alcohol polyoxyethylene ether, 5% to 20% of moisturizing agent, and the balance of water; The waterborne polyurethane resin is prepared from the following raw materials in parts by weight: 12-20 parts of polyester polyol / polyether polyol, 5-10 parts of diisocyanate, 0.5-1.5 parts of 2,2-dihydroxymethylpropionic acid, 0.1-1 parts of small molecule polyol, 0.001-0.01 parts of catalyst, 15-25 parts of acetone, 0.5-1 parts of neutralizer, 45-60 parts of water, and 0.3-1.5 parts of amine chain extender.

2. A digital direct-injection ink according to claim 1, characterized in that: The humectant is one or more of ethylene glycol, polyethylene glycol, diethylene glycol, propylene glycol and glycerol; the surfactant is a nonionic surfactant, and the nonionic surfactant is at least one of Surfynol 465 and Surfynol 485.

3. A digital direct-injection ink according to claim 1, characterized in that: The invention comprises the following components by mass percentage: 20% of pigment paste, 2% of surfactant, 15% of waterborne polyurethane resin, 5% of polyurethane acrylate dispersion, 12% of fatty alcohol polyoxyethylene ether, 15% of moisturizing agent, and the balance of water.

4. The digital direct-injection ink according to claim 1, characterized in that: The preparation method of the waterborne polyurethane resin comprises the following steps: S1. The polyester polyol / polyether polyol is mixed with diisocyanate and reacted at 86 to 88°C for 1 to 3 hours to obtain material A; S2. After the material A is cooled, a small molecule polyol is added and reacted at 80 to 88° C. for 0.1 to 1 hour to obtain material B; S3. After the material B is cooled, 2,2-dimethylol propionic acid, a catalyst and acetone are added in sequence, and the reaction is continued at 60 to 70 ° C for 2 to 5 hours to obtain a polyurethane prepolymer; S4. The polyurethane prepolymer is cooled to 45 to 50°C, a neutralizing agent is added for neutralization reaction; water is then added for emulsification, an amine chain extender is added, and the reaction is stirred to obtain material C; S5. distill material C under reduced pressure at 45-55° C. to obtain the water-based polyurethane resin for digital direct-jet ink.

5. A digital direct-injection ink according to claim 4, characterized in that: In step S1, the polyester polyol / polyether polyol is heated to 100-105° C. and vacuum-dehydrated for 1-2 hours before the reaction.

6. A digital direct-injection ink according to claim 4, characterized in that: In step S1, the molecular weight of the polyester polyol / polyether polyol is between 1000 and 2000; and / or, The polyester polyol / polyether polyol is selected from at least one of polyhexamethylene adipate diol, polyhexamethylene adipate neopentyl glycol ester diol, polyneopentyl adipate diol, polycaprolactone diol, polycarbonate diol, and polytetramethylene ether diol.

7. The digital direct-injection ink according to claim 4, characterized in that: In step S1, the diisocyanate is selected from at least one of isophorone diisocyanate and dicyclohexylmethane diisocyanate.

8. The digital direct-injection ink according to claim 4, characterized in that: In step S2, the small molecule polyol is selected from at least one of butanediol, hexanediol, neopentyl glycol and diethylene glycol.

9. The digital direct-injection ink according to claim 4, characterized in that: In step S3, the catalyst is selected from at least one of an organic bismuth catalyst and an organic zinc catalyst.

10. The digital direct-injection ink according to claim 4, characterized in that: In step S4, the neutralizing agent is selected from at least one of triethylamine and sodium hydroxide; and / or, The amine chain extender is selected from at least one of ethylenediamine and hexamethylenediamine.

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