Ink-jet printing water-based UV ink and preparation method thereof

Abstract

The invention relates to ink-jet printing water-based UV ink and a preparation method thereof, and belongs to the technical field of UV ink. The preparation method of the ink-jet printing water-based UV ink comprises the following steps: putting dehydrated dihydric alcohol into a reaction kettle, adding MDI, HDI and an organic tin catalyst, stirring for reaction, adding a chain extender A and a chain extender B for continuous reaction, adding a chain extender C, uniformly mixing, cooling, adding a neutralizer and deionized water, and stirring for dispersion to obtain a polyurethane emulsion; uniformly stirring the modified pigment, the surfactant and 2 / 3 of the solvent to obtain dispersion liquid; and adding the polyurethane emulsion and the rest of the solvent into the dispersion liquid, and fully stirring and mixing to obtain the coating. The synthesis method of the UV ink is simple and convenient, the preparation condition is mild, an environment-friendly solvent system can be adopted, and large-scale production and application can be conveniently achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of UV inks, and relates to an inkjet printing water-based UV ink and a preparation method thereof. Background Art

[0002] UV curing inkjet technology is an advanced printing technology that ingeniously combines the convenience of inkjet printing with the high efficiency of the photo-curing system. The main advantage of this technology is that it is more environmentally friendly during the printing process. In addition, it also has the characteristics of low energy consumption and rapid curing, which gives it a significant advantage in production efficiency. UV curing inkjet technology is applicable to a variety of different substrates, whether it is paper, plastic or metal, and can provide excellent printing quality. Its excellent comprehensive performance makes it a very promising technology in the field of industrial printing.

[0003] Water-based UV inkjet ink is an innovative ink technology that combines the environmental protection characteristics of water-based ink and the rapid curing advantages of UV ink. This ink can be printed and dried quickly during the printing process, has the characteristics of low viscosity and thin film formation, and has almost no odor, providing a more comfortable and healthy working environment for users. However, the dispersion stability of the color paste has a decisive impact on the ink quality. Although the existing water-based UV inkjet inks show good printing fluidity, the dispersion of the color paste pigments is not good, which leads to insufficient adhesion after the inkjet ink is cured; in addition, the water-based UV inkjet ink must also have weather resistance in a sunny environment during long-term storage.

[0004] Patent document CN116102919A discloses a water-based ink and its printing process. The ink includes 25-35 parts by weight of water-based polyurethane, 8-12 parts by weight of water-based vinyl chloride-vinyl acetate emulsion, 23-37 parts by weight of fluorine-modified polyacrylate emulsion, 3-5 parts by weight of colorant, 1-2 parts by weight of silane coupling agent, and 25 parts by weight of ethanol solution; this ink can improve the printing speed of PVC and has weather resistance and low temperature resistance. However, in this patent document, the fluorine-modified polyacrylate mainly improves weather resistance and hydrophobicity, and has limited direct contribution to adhesion. The amount of the decoupling agent-modified pigment is low, and the silane coupling agent may not be sufficient to fully improve the interfacial bonding force between the resin and the substrate, especially for the fluorine-modified component with high surface energy, and there are limitations in improving its dispersion. Summary of the Invention

[0005] The object of the present invention is to provide an inkjet printing aqueous UV ink and a preparation method thereof. The present invention provides a polyurethane compound containing aldehyde groups as an ink binder, which has excellent adhesion performance and high-temperature resistance performance and has good application value. The polyurethane compound provided by the present invention is mainly obtained by grafting acrolein with thioglycerol. The aldehyde group groups on the main chain of the polyurethane compound enable it to interact with the amino groups on the surface of the poly-dopamine-coated pigment, increasing the compatibility of the pigment, improving the adhesion of the ink, and at the same time improving its high-temperature resistance performance. The synthesis method of the UV ink involved in the present invention is simple, the preparation conditions are mild, and an environmentally friendly solvent system can be used, which is convenient for large-scale production and application.

[0006] The object of the present invention can be achieved by the following technical solutions:

[0007] A preparation method of an inkjet printing aqueous UV ink comprises the following steps:

[0008] S1. Preparation of polyurethane emulsion: Place the dehydrated diol in a reaction kettle, add MDI, HDI and an organotin catalyst and stir to react, add chain extender A and chain extender B and continue to react, add chain extender C, mix evenly, then cool down, add a neutralizer and deionized water and stir to disperse to obtain a polyurethane emulsion;

[0009] S2. Preparation of dispersion: Stir the modified pigment, surfactant and 2 / 3 of the solvent evenly to obtain a dispersion;

[0010] S3. Preparation of ink: Add the polyurethane emulsion and the remaining solvent to the dispersion and stir and mix evenly to obtain the ink.

[0011] As a preferred technical solution of the present invention, in step S1, the mass ratio of the diol, MDI, HDI, organotin catalyst, chain extender A, chain extender B, chain extender C, neutralizer and deionized water is 22-26: 2-3: 11-14: 0.15-0.18: 1.2-1.4: 1.5-1.8: 0.6-0.8: 2.0-2.4: 70-80.

[0012] As a preferred technical solution of the present invention, in step S1, the diol is PBA, that is, poly(butylene adipate), Mn = 1000; the organotin catalyst is organotin catalyst T-12; the chain extender A is 2,2-dimethylolbutyric acid; the chain extender C is one or more of 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol and neopentyl glycol; the neutralizer is triethylamine.

[0013] As a preferred technical solution of the present invention, in step S1, the stirring reaction is carried out at 65 - 80 °C for 1.5 - 2.0 h; the time for the continuous reaction is 1.0 - 1.5 h; the temperature reduction is to room temperature; the stirring and dispersion is carried out at 500 - 800 r / min for 50 - 60 min.

[0014] As a preferred technical solution of the present invention, in steps S2 - S3, the uniform stirring is carried out at 500 - 800 r / min for 40 - 50 min; the stirring and mixing is carried out at 800 - 1000 r / min for 20 - 30 min.

[0015] As a preferred technical solution of the present invention, in steps S2 - S3, the mass ratio of the polyurethane emulsion, modified pigment, surfactant and solvent is 30 - 35:20 - 23:2 - 3:50 - 62; the surfactant is an anionic surfactant, sodium dodecyl sulfonate; the solvent is composed of an organic solvent and deionized water. Specifically, the solvent is composed of isopropanol and deionized water in a mass ratio of 1:4.

[0016] As a preferred technical solution of the present invention, the preparation method of the chain extender B includes: placing acrolein, thioglycerol and n - hexane in a reaction kettle and mixing them evenly, adding a photoinitiator and treating them under UV light irradiation, then placing them in a rotary evaporator to remove the solvent, and then washing with water and subjecting to vacuum distillation to obtain the product.

[0017] As a preferred technical solution of the present invention, the UV light irradiation is carried out under 365 nm ultraviolet light for 3 - 4 h; the mass ratio of acrolein, thioglycerol, n - hexane and photoinitiator is 10 - 13:22 - 28:20 - 30:0.7 - 0.8; the photoinitiator is photoinitiator 1173.

[0018] As a preferred technical solution of the present invention, the preparation method of the modified pigment includes the following steps:

[0019] Mix dopamine hydrochloride and 2 / 3 Tris - HCl buffer solution to obtain a dopamine hydrochloride solution. Mix the pigment and the remaining Tris - HCl buffer solution and carry out ultrasonic treatment, add the dopamine hydrochloride solution and carry out ultrasonic mixing and stirring treatment, then centrifuge, wash, and vacuum dry to obtain the product.

[0020] As a preferred technical solution of the present invention, the mass ratio of dopamine hydrochloride, Tris-HCl buffer solution and pigment is 1.0-1.3: 300-320: 10-12; the ultrasonic mixing is carried out at 150-180 W for 10-15 min; the stirring treatment is carried out at 180-200 r / min for 10-12 h; the centrifugation is carried out at 8000-10000 r / min for 10 min; the washing is carried out by washing 3 times with deionized water; the vacuum drying is carried out at 60 °C until constant weight; the concentration of the Tris-HCl buffer solution is 1 M and the pH = 8.5.

[0021] Advantages of the present invention:

[0022] 1. The present invention provides a polyurethane compound containing aldehyde groups, which is used as an ink binder and has excellent adhesion performance and high-temperature resistance performance, and has good application value.

[0023] 2. The polyurethane compound provided by the present invention is mainly obtained by grafting acrolein with thioglycerol. The aldehyde groups in the main chain of the polyurethane compound enable it to interact with the amino groups on the surface of the polydopamine-coated pigment, increase the compatibility of the pigment, and improve the adhesion and high-temperature resistance performance of the ink while improving the adhesion of the ink.

[0024] 3. The synthesis method of the UV ink involved in the present invention is simple, the preparation conditions are mild, and an environmentally friendly solvent system can be used, which is convenient for large-scale production and application. Specific embodiments

[0025] To further illustrate the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following examples are used to describe in detail the specific embodiments, structures, features and effects of the present invention.

[0026] Example 1

[0027] A preparation method of an inkjet printing aqueous UV ink includes the following steps.

[0028] S1. Preparation of polyurethane emulsion: After dehydrating the diol under vacuum at 110°C and 0.09 MPa for 1 h, it is placed in a reaction kettle. MDI, HDI, and an organotin catalyst are added and stirred at 65°C for 1.5 h. Chain extender A and chain extender B are added and the reaction continues for 1.0 h. After adding chain extender C and mixing evenly, the temperature is lowered to room temperature. A neutralizer and deionized water are added and stirred at 500 r / min for 50 min to obtain a polyurethane emulsion; wherein, the mass ratio of the diol, MDI, HDI, organotin catalyst, chain extender A, chain extender B, chain extender C, neutralizer, and deionized water is 22:2:11:0.15:1.2:1.5:0.6:2.0:70; the diol is poly(butylene adipate), Mn = 1000; the organotin catalyst is organotin catalyst T-12; the chain extender A is 2,2-dimethylolbutanoic acid; the chain extender C is 1,3-propanediol; the neutralizer is triethylamine;

[0029] S2. Preparation of dispersion: The modified pigment, surfactant, and 2 / 3 of the solvent are stirred at 500 r / min for 40 min to obtain a dispersion;

[0030] S3. Preparation of ink: The polyurethane emulsion and the remaining solvent are added to the dispersion and stirred at 800 r / min for 20 min to obtain the ink.

[0031] The mass ratio of the polyurethane emulsion, modified pigment, surfactant, and solvent is 30:20:2:50; the surfactant is sodium dodecyl sulfonate; the solvent is composed of isopropanol and deionized water in a mass ratio of 1:4;

[0032] The preparation method of the chain extender B includes: placing acrolein, thioglycerol, and n-hexane in a reaction kettle and mixing evenly, adding a photoinitiator, irradiating with ultraviolet light at 365 nm for 3 h, placing it in a rotary evaporator to remove the solvent, and then washing with water and performing vacuum distillation to obtain it; wherein, the UV light irradiation is; the mass ratio of acrolein, thioglycerol, n-hexane, and photoinitiator is 10:22:20:0.7; the photoinitiator is photoinitiator 1173.

[0033] The preparation method of the modified pigment includes the following steps:

[0034] Mix dopamine hydrochloride and 2 / 3 Tris-HCl buffer to obtain a dopamine hydrochloride solution. Mix the pigment and the remaining Tris-HCl buffer, and ultrasonicate at 150 W for 10 min. Add the dopamine hydrochloride solution and ultrasonically mix at 150 W for 5 min, then stir at 180 r / min for 10 h, centrifuge at 8000 r / min for 10 min, wash 3 times with deionized water, and vacuum dry at 60 °C to constant weight to obtain the product. Among them, the mass ratio of dopamine hydrochloride, Tris-HCl buffer, and pigment is 1.0:300:10; the pigment is carbon black.

[0035] Example 2

[0036] A preparation method of an inkjet printing aqueous UV ink comprises the following steps.

[0037] S1. Preparation of polyurethane emulsion: After removing water by vacuum at 110 °C and 0.09 MPa for 1 h for the diol, place it in a reaction kettle, add MDI, HDI, and an organotin catalyst, stir at 72 °C for 1.8 h, add chain extender A and chain extender B and continue to react for 1.2 h, add chain extender C and mix evenly, then cool to room temperature, add a neutralizing agent and deionized water, and stir at 650 r / min for 55 min to obtain a polyurethane emulsion. Among them, the mass ratio of the diol, MDI, HDI, organotin catalyst, chain extender A, chain extender B, chain extender C, neutralizing agent, and deionized water is 24:2.5:12:0.16:1.3:1.6:0.7:2.2:75; the diol is poly(1,4-butylene adipate), Mn = 1000; the organotin catalyst is organotin catalyst T-12; the chain extender A is 2,2-dimethylolbutyric acid; the chain extender C is 1,3-propanediol; the neutralizing agent is triethylamine;

[0038] S2. Preparation of dispersion: Stir the modified pigment, surfactant, and 2 / 3 solvent at 650 r / min for 45 min to obtain a dispersion.

[0039] S3. Preparation of ink: Add the polyurethane emulsion and the remaining solvent to the dispersion and stir at 900 r / min for 25 min to obtain the ink.

[0040] The mass ratio of the polyurethane emulsion, modified pigment, surfactant, and solvent is 32:22:2.5:56; the surfactant is sodium dodecyl sulfonate; the solvent is composed of isopropanol and deionized water in a mass ratio of 1:4.

[0041] The preparation method of the chain extender B includes: placing acrolein, thioglycerol and n-hexane in a reaction kettle and mixing them evenly, adding a photoinitiator and irradiating with 365 nm ultraviolet light for 3.5 h, placing it in a rotary evaporator to remove the solvent, and then washing with water and performing vacuum distillation to obtain it; wherein, the UV light irradiation is; the mass ratio of acrolein, thioglycerol, n-hexane and the photoinitiator is 12:25:25:0.75; the photoinitiator is photoinitiator 1173.

[0042] The preparation method of the modified pigment includes the following steps:

[0043] Mix dopamine hydrochloride and 2 / 3 Tris-HCl buffer solution to obtain a dopamine hydrochloride solution. Mix the pigment and the remaining Tris-HCl buffer solution and ultrasonicate at 165 W for 12 min. Add the dopamine hydrochloride solution and ultrasonically mix at 165 W for 8 min, then stir at 190 r / min for 11 h, centrifuge at 9000 r / min for 10 min, wash 3 times with deionized water, and dry in vacuum at 60 °C to constant weight to obtain it; wherein, the mass ratio of dopamine hydrochloride, Tris-HCl buffer solution and the pigment is 1.2:310:11; the pigment is carbon black.

[0044] Example 3

[0045] A preparation method of an inkjet printing aqueous UV ink includes the following steps.

[0046] S1. Preparation of polyurethane emulsion: After vacuum removing water from the diol at 110 °C and 0.09 MPa for 1 h, place it in a reaction kettle, add MDI, HDI and an organotin catalyst and stir at 80 °C for 2.0 h, add chain extender A and chain extender B and continue to react for 1.5 h, add chain extender C and mix evenly, then cool down to room temperature, add a neutralizer and deionized water and stir at 800 r / min for 60 min to obtain a polyurethane emulsion; wherein, the mass ratio of the diol, MDI, HDI, organotin catalyst, chain extender A, chain extender B, chain extender C, neutralizer and deionized water is 26:3:14:0.18:1.4:1.8:0.8:2.4:80; the diol is poly(1,4-butylene adipate), Mn = 1000; the organotin catalyst is organotin catalyst T-12; the chain extender A is 2,2-dimethylolbutanoic acid; the chain extender C is 1,3-propanediol; the neutralizer is triethylamine;

[0047] S2. Preparation of dispersion: Mix the modified pigment, surfactant and 2 / 3 solvent and stir at 800 r / min for 50 min to obtain a dispersion;

[0048] S3. Preparation of ink: Add the polyurethane emulsion and the remaining solvent to the dispersion and stir at 1000 r / min for 30 min to obtain it.

[0049] The mass ratio of the polyurethane emulsion, modified pigment, surfactant, and solvent is 35:23:3:62; the surfactant is sodium dodecyl sulfonate; the solvent is composed of isopropyl alcohol and deionized water in a mass ratio of 1:4;

[0050] The preparation method of the chain extender B includes: placing acrolein, thioglycerol, and n-hexane in a reaction kettle and mixing them evenly, adding a photoinitiator, irradiating with 365 nm ultraviolet light for 4 h, placing it in a rotary evaporator to remove the solvent, then washing with water and performing vacuum distillation to obtain it; among them, the UV light irradiation is; the mass ratio of acrolein, thioglycerol, n-hexane, and photoinitiator is 13:28:30:0.8; the photoinitiator is photoinitiator 1173.

[0051] The preparation method of the modified pigment includes the following steps:

[0052] Mix dopamine hydrochloride and 2 / 3 Tris-HCl buffer solution to obtain a dopamine hydrochloride solution. Mix the pigment and the remaining Tris-HCl buffer solution, ultrasonicate at 180 W for 15 min, add the dopamine hydrochloride solution, ultrasonicate and mix at 180 W for 10 min, then stir at 200 r / min for 12 h, centrifuge at 10,000 r / min for 10 min, wash with deionized water 3 times, and vacuum dry at 60 °C to constant weight to obtain it; among them, the mass ratio of dopamine hydrochloride, Tris-HCl buffer solution, and pigment is 1.3:320:12; the pigment is carbon black.

[0053] Comparative Example 1

[0054] Compared with Example 3, the difference in Comparative Example 1 is that acrolein is used instead of chain extender B, and the other components, preparation steps, and parameters are the same.

[0055] Comparative Example 2

[0056] Compared with Example 3, the difference in Comparative Example 2 is that thioglycerol is used instead of chain extender B, and the other components, preparation steps, and parameters are the same.

[0057] Comparative Example 3

[0058] Compared with Example 3, the difference in Comparative Example 3 is that chain extender C is used instead of chain extender B, and the other components, preparation steps, and parameters are the same.

[0059] Comparative Example 4

[0060] Compared with Example 3, the difference in Comparative Example 4 is that the pigment is not modified, and the other components, preparation steps, and parameters are the same.

[0061] The inks prepared in Examples 1-3 and Comparative Examples 1-4 were respectively subjected to the following performance tests, and the test results are shown in Table 1.

[0062] Adhesion test: Treated according to the 1-mm crosshatch method in accordance with GB / T 9286-88.

[0063] Temperature resistance test: In accordance with GB / T1735;

[0064] Table 1

[0065] Adhesion (%) Temperature resistance (°C) Printed pattern condition Example 1 98 265 The pattern is clear and the color development is normal Example 2 97 263 The pattern is clear and the color development is normal Example 3 95 258 The pattern is clear and the color development is normal Comparative example 1 82 213 The pattern is relatively clear and the color development is normal Comparative example 2 85 186 The pattern is relatively clear and the color development is normal Comparative example 3 76 182 Part of the pattern is unclear and the color development is normal Comparative example 4 71 168 Part of the pattern is unclear and the local color development is relatively light

[0066] From the test results in Table 1, it can be seen that compared with Comparative Examples 1-4, the UV inks prepared in Examples 1-3 of the present invention have excellent adhesion fastness and high temperature resistance, and are smooth in printing and have good color development effects.

[0067] In the present invention, by subjecting acrolein to a click reaction with thioglycerol, multiple active hydroxyl groups are introduced, which can participate in the reaction with isocyanate, so that while an aldehyde group is introduced into the main chain of the polyurethane compound, dopamine is used to coat the pigment, making the surface of the pigment rich in amino groups, which can interact with the aldehyde groups in the polyurethane emulsion, increasing the dispersibility of the pigment and improving the binding force between the pigment and the polyurethane compound, and a high-performance ink coating with high hardness, high adhesion and high temperature resistance of the UV ink can be achieved. The UV ink prepared in the present invention has a wide range of applicability and can be applied to various scenarios such as textiles, woodware and metals.

[0068] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content to make equivalent embodiments with equivalent changes within the scope of the technical solution of the present invention. However, any indirect modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing water-based UV ink for inkjet printing, characterized in that: The preparation method comprises the following steps: S1. Preparation of polyurethane emulsion: placing the dehydrated diol in a reaction kettle, adding MDI, HDI and an organic tin catalyst to stir and react, adding chain extender A and chain extender B to continue the reaction, adding chain extender C to mix well and then cooling, adding a neutralizer and deionized water to stir and disperse, and obtaining a polyurethane emulsion; S2, preparation of dispersion: uniformly stirring the modified pigment, surfactant and 2 / 3 solvent to obtain a dispersion; S3, preparation of ink: adding polyurethane emulsion and remaining solvent to the dispersion and stirring and mixing thoroughly to obtain; The preparation method of the chain extender B comprises: placing acrolein, thioglycerol and n-hexane in a reaction kettle and mixing them evenly, adding a photoinitiator and irradiating them with UV light, placing them in a rotary evaporator to remove the solvent, and then washing with water and distilling under reduced pressure to obtain the chain extender B; The preparation method of the modified pigment comprises the following steps: Dopamine hydrochloride and 2 / 3 Tris-HCl buffer are mixed to obtain a dopamine hydrochloride solution, the pigment and the remaining Tris-HCl buffer are mixed and ultrasonically treated, the dopamine hydrochloride solution is added, ultrasonically mixed and stirred, centrifuged, washed, and vacuum dried to obtain the product.

2. The method for preparing a water-based UV ink for inkjet printing according to claim 1, characterized in that: In step S1, the mass ratio of the diol, MDI, HDI, organic tin catalyst, chain extender A, chain extender B, chain extender C, neutralizer and deionized water is 22-26: 2-3: 11-14: 0.15-0.18: 1.2-1.4: 1.5-1.8: 0.6-0.8: 2.0-2.4: 70-80.

3. The method for preparing a water-based UV ink for inkjet printing according to claim 1, characterized in that: In step S1, the diol is PBA; the chain extender A is 2,2-dihydroxymethylbutyric acid; the chain extender C is one or more of 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol and neopentyl glycol; and the neutralizer is triethylamine.

4. The method for preparing a water-based UV ink for inkjet printing according to claim 1, characterized in that: In step S1, the stirring reaction is performed at 65-80°C for 1.5-2.0 hours; the continued reaction time is 1.0-1.5 hours; and the stirring dispersion is performed at 500-800 r / min for 50-60 minutes.

5. The method for preparing a water-based UV ink for inkjet printing according to claim 1, characterized in that: In steps S2-S3, the uniform stirring is performed at 500-800 r / min for 40-50 min; the stirring and mixing is performed at 800-1000 r / min for 20-30 min.

6. The method for preparing a water-based UV ink for inkjet printing according to claim 1, characterized in that: The mass ratio of the polyurethane emulsion, the modified pigment, the surfactant and the solvent is 30-35:20-23:2-3:50-62; the surfactant is an anionic surfactant; and the solvent consists of an organic solvent and deionized water.

7. The method for preparing a water-based UV ink for inkjet printing according to claim 1, characterized in that: In the preparation of the chain extender B, the UV light irradiation is 365nm ultraviolet irradiation for 3-4h; the mass ratio of acrolein, thioglycerol, n-hexane and photoinitiator is 10-13:22-28:20-30:0.7-0.

8.

8. The method for preparing a water-based UV ink for inkjet printing according to claim 1, characterized in that: The mass ratio of dopamine hydrochloride, Tris-HCl buffer and pigment is 1.0-1.3:300-320:10-12.

9. The method for preparing a water-based UV ink for inkjet printing according to claim 1, characterized in that: The ultrasonic mixing is 150-180W ultrasound for 10-15 minutes; the stirring treatment is stirring at 180-200r / min for 10-12h.

10. An inkjet printing water-based UV ink prepared by the preparation method according to any one of claims 1 to 9.