Weak solvent ink for ink-jet printer and preparation method of weak solvent ink

Abstract

The invention discloses weak-solvent ink for an ink-jet printer and a preparation method of the weak-solvent ink, and relates to the technical field of printing ink. The preparation method comprises the following steps: carrying out free radical polymerization on 4-hydroxystyrene and hydroxyethyl methylacrylate to prepare modified matrix resin; and fully mixing the modified matrix resin with a solvent, modified barium carbonate, a pigment, a dispersing agent, a wetting agent, a defoaming agent, a bacteriostatic agent and a pH regulator to prepare the weak-solvent ink for the ink-jet printer. The ink has excellent oxidation resistance without additional addition of an antioxidant, and is also very excellent in stability; and moreover, the volatilization and drying speed of the ink after spraying is high, the used solvent is environment-friendly and harmless, the emission of VOCs is reduced, and the ink has a wide application prospect.

Description

Technical Field

[0001] This application relates to the technical field of printing inks, and particularly to a weakly solvent ink for inkjet printers and a preparation method thereof. Background Art

[0002] In the field of modern printing technology, inkjet printers, with their precise image reproduction capabilities and diverse application scenarios, are widely used in many industries such as office, advertising, decoration, packaging, and textile printing and dyeing. Among them, weakly solvent inks are gradually becoming one of the mainstream printing consumables due to their unique advantages.

[0003] However, traditional inkjet printing inks face severe oxidation challenges when dealing with outdoor applications or long-term storage requirements. Whether it is outdoor advertising signs, vehicle body stickers, or prints of artworks for long-term preservation, the oxidation effect will cause the ink color to fade, corrode the print head, and reduce the printing quality. To address this issue, the common practice is to add antioxidants to the ink. Although antioxidants can delay the oxidation process to a certain extent, they also bring a series of drawbacks. On the one hand, the additional antioxidants increase the compositional complexity of the ink, and it is difficult to ensure the compatibility of different antioxidants with other components in the ink system, which easily leads to ink stability problems such as precipitation, stratification, and even nozzle clogging. On the other hand, some antioxidants themselves have certain volatility or toxicity, and with the use of the ink, they will pose potential hazards to the environment and the health of operators, which is contrary to the current development concept of green environmental protection and safe production.

[0004] Chinese patent application with publication number CN 111662591A discloses a preparation method of a highly weather-resistant weakly solvent ink for outdoor use. The ink includes the following components in weight ratio: 5 - 10 parts of functional solid resin, 5 - 10 parts of silicone solid resin, 5 - 10 parts of organic pigment, 60 - 80 parts of high flash point environmentally friendly weakly solvent, 0.1 - 2 parts of ultraviolet absorber, 0.1 - 2 parts of surfactant, 0.5 - 1 part of dispersant, and 0.1 - 2 parts of antioxidant. The ink not only has excellent outdoor expressiveness and weather resistance, does not fade or peel off after long-term outdoor use, and can resist the influence of UV light; but also does not contain toxic solvents such as benzene, toluene, xylene, cyclohexanone, etc., overcoming the defect that most existing solvent-based inks are prone to emit a large amount of special odors.

[0005] However, the above technical solution still requires the additional addition of antioxidants, and there is still a large room for improvement in the stability of the ink. Summary of the Invention

[0006] In view of the deficiencies of the prior art, the present application provides a weakly solvent ink for an inkjet printer and a preparation method thereof. By carrying out free radical polymerization of 4-hydroxystyrene and 2-hydroxyethyl methacrylate, a modified matrix resin is prepared; and the modified matrix resin is fully mixed with a solvent, modified barium carbonate, a pigment, a dispersant, a wetting agent, an antifoaming agent, an antibacterial agent and a pH regulator to prepare a weakly solvent ink for an inkjet printer. This ink has excellent antioxidant performance without the need to additionally add an antioxidant, and has very excellent stability, with broad application prospects.

[0007] To achieve the above object, the present application adopts the following technical solutions:

[0008] In a first aspect, the present application provides a weakly solvent ink for an inkjet printer, including a modified matrix resin, a solvent, modified barium carbonate, a pigment, a dispersant, a wetting agent, an antifoaming agent, an antibacterial agent and a pH regulator; the modified matrix resin is obtained by free radical polymerization of 4-hydroxystyrene and 2-hydroxyethyl methacrylate.

[0009] In a second aspect, the present application provides a preparation method of a weakly solvent ink for an inkjet printer, including the following steps:

[0010] Add ethanol, 4-hydroxystyrene, 2-hydroxyethyl methacrylate and an initiator into a reaction kettle protected by nitrogen.

[0011] The substances in the reaction kettle carry out a free radical polymerization reaction at a first temperature for a first time, and after discharging, a modified matrix resin is obtained.

[0012] Add the modified matrix resin into the solvent, and stir at a second temperature for a second time to obtain a resin solution.

[0013] Mix the pigment and the dispersant and then add them into the resin solution, and stir at a first rotation speed for a third time.

[0014] Add modified barium carbonate, a wetting agent, an antifoaming agent, an antibacterial agent and a pH regulator into the resin solution, and adjust the pH to a predetermined range.

[0015] Continue to stir the resin solution at a first rotation speed for a fourth time, and filter through a 0.5 μm filter element to obtain a weakly solvent ink for an inkjet printer.

[0016] Beneficial technical effects:

[0017] In this application, a modified matrix resin with phenolic hydroxyl groups and hydroxyl groups connected to the main molecular chain is prepared by free radical polymerization of 4-hydroxystyrene and 2-hydroxyethyl methacrylate. The phenolic hydroxyl groups can provide hydrogen atoms to combine with free radicals such as peroxy radicals ROO· and alkoxy radicals RO· generated in the ink or the environment, convert them into stable non-free radical products, and at the same time generate stable phenoxy radicals by themselves, thereby interrupting the oxidation chain reaction. Therefore, it is not necessary to add antioxidants to prevent the oxidation and deterioration of ink components, endowing the ink with strong antioxidant ability, and at the same time avoiding problems such as sedimentation, stratification or volatilization that may occur due to the difficulty in ensuring the compatibility of externally added antioxidants with other components in the ink system, enhancing the stability of the ink. Moreover, the addition of modified barium carbonate can buffer the acidic components in the ink system, further enhancing the stability and antioxidant properties of the ink. In addition, the resin polymer chains generated by polymerization will form a physical cross-linking network after film formation, blocking the penetration of oxygen and moisture, delaying the photo-oxygen aging of the ink, and further improving the antioxidant properties of the ink. In addition, the presence of hydroxyl groups can form hydrogen bonds or covalent bonds between the ink and the surface of a specific substrate (such as paper) to be sprayed. On the one hand, it enhances the adhesion of the ink to the surface of a specific substrate (such as paper); on the other hand, the polarity of the hydroxyl groups can also enhance the compatibility between the modified matrix resin and the solvent used in this application, further enhancing the stability of the ink, and also making it easier for solvent molecules to escape from the resin network. Finally, the drying rate of the ink after spraying and volatilization is accelerated; and the solvent used in this application is environmentally friendly and harmless, reducing the emission of VOCs. Brief Description of the Drawings

[0018] Figure 1 It is a schematic chemical reaction diagram for preparing the modified matrix resin.

[0019] Figure 2 It is a schematic process diagram for preparing the weak solvent ink for inkjet printers.

[0020] Figure 3 It is a physical picture of the prepared weak solvent ink for inkjet printers. Detailed Description of the Embodiments

[0021] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application clearer and more understandable, the following will further elaborate on this application in combination with embodiments. However, this should not be construed as limiting the scope of this application to the following examples. Without departing from the above method concept of this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of this application.

[0022] In this application, the terms used are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0023] As used in this application, the singular forms "is", "a", "any one", and "the" are intended to include the plural forms, unless the context clearly indicates otherwise.

[0024] In addition, if the terms "first" and "second" appear in this application, they are only for descriptive purposes and should not be construed as indicating or implying relative importance.

[0025] In a first aspect, this application provides a weak solvent ink for an inkjet printer, which includes a modified matrix resin, a solvent, modified barium carbonate, a pigment, a dispersant, a wetting agent, an antifoaming agent, an antibacterial agent, and a pH regulator; the modified matrix resin is obtained by free radical polymerization of 4-hydroxystyrene and 2-hydroxyethyl methacrylate, and the reaction is as Figure 1 shown.

[0026] In a possible implementation manner, the structure of the modified matrix resin includes:

[0027] wherein, n is an integer between 10 and 50.

[0028] In a possible implementation manner, the mass ratio of the modified matrix resin, the solvent, the modified barium carbonate, the pigment, the dispersant, the wetting agent, the antifoaming agent, the antibacterial agent, and the pH regulator is (20 - 35):(40 - 50):(10 - 20):(8 - 15):(1 - 2):(0.5 - 1):(0.5 - 1):(0.5 - 1):(1 - 3).

[0029] In a possible implementation manner, the preparation method of the modified barium carbonate includes:

[0030] At 60 - 80 °C, while stirring, drop the carbonate solution into the barium salt solution, and at the same time add the titanate solution, and control the dropping rate to keep the pH at 8 - 10;

[0031] Continue to stir for 30 - 60 min, filter out and collect the solid, and wash the obtained solid with deionized water and absolute ethanol two to three times in sequence;

[0032] Vacuum dry the washed solid at 60 - 80 °C for 4 - 8 h, and pulverize it through a 200 - mesh sieve to obtain the modified barium carbonate.

[0033] In a possible implementation manner, the dosage of the titanate coupling agent is 0.5 - 1.5% of the mass of the barium salt solution; the titanate coupling agent includes at least one of titanate coupling agent TC - 2, titanate coupling agent TC - 27, and titanate coupling agent TC - 114.

[0034] In a possible implementation, the solvent includes at least one of diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, diethylene glycol tetramethyl ether, and methyl tert-butyl ether.

[0035] In a possible implementation, the pigment includes any one of carbon black, titanium dioxide, phthalocyanine blue, quinacridone red, and benzimidazolone yellow.

[0036] In a possible implementation, the dispersant includes any one of BYK-163, EFKA-4010, and tributyl phosphate.

[0037] In a possible implementation, the wetting agent includes any one of BYK-346, BYK-348, and Capstone FS-3100.

[0038] In a possible implementation, the defoaming agent includes any one of dimethyl silicone oil and polyoxyethylene polyoxypropylene glycerol ether.

[0039] In a possible implementation, the bacteriostatic agent includes any one of 2-n-octyl-4-isothiazolin-3-one and 1,2-benzisothiazolin-3-one.

[0040] In a possible implementation, the pH regulator includes any one of N,N-dimethylethylamine, triethanolamine, and 2-amino-2-methyl-1-propanol.

[0041] In a second aspect, the present application provides a method for preparing a weakly solvent ink for an inkjet printer, as Figure 2 shown, comprising the following steps:

[0042] Add ethanol, 4-hydroxystyrene, hydroxyethyl methacrylate, and an initiator into a reaction kettle under nitrogen protection;

[0043] The substances in the reaction kettle are subjected to a free radical polymerization reaction at a first temperature for a first period of time, and after discharging, a modified matrix resin is obtained;

[0044] Add the modified matrix resin into the solvent, and stir at a second temperature for a second period of time to obtain a resin solution;

[0045] Mix the pigment and the dispersant and then add them into the resin solution, and stir at a first rotation speed for a third period of time;

[0046] Add modified barium carbonate, wetting agent, defoaming agent, bacteriostatic agent, and pH regulator into the resin solution, and adjust the pH to a predetermined range;

[0047] Continue to stir the resin solution at the first rotation speed for a fourth period of time, and filter through a 0.5 μm filter element to obtain a weakly solvent ink for an inkjet printer, as Figure 3as shown

[0048] In a possible implementation, the mass ratio of the ethanol, 4-hydroxystyrene, 2-hydroxyethyl methacrylate, and initiator is (60-70):(10-20):(15-25):(0.5-1).

[0049] In a possible implementation, the initiator includes at least one of azobisisobutyronitrile, azobisisoheptonitrile, and lauroyl peroxide.

[0050] In a possible implementation, the first temperature is 70-80 °C, and the second temperature is 50-60 °C; the first time is 6-8 h, the second time is 1-2 h, the third time is 0.5-1 h, and the fourth time is 10-20 min; the first rotation speed is 800-1200 rpm; the pH is in a predetermined range of 8-9.

[0051] The following will specifically describe an inkjet printer weak solvent ink and its preparation method provided by the present application in combination with different embodiments.

[0052] Example 1:

[0053] As Figure 2 shown, a preparation method of an inkjet printer weak solvent ink includes the following steps:

[0054] 1. Add ethanol, 4-hydroxystyrene, 2-hydroxyethyl methacrylate, and azobisisobutyronitrile into a reaction kettle under nitrogen protection, and the mass ratio of ethanol, 4-hydroxystyrene, 2-hydroxyethyl methacrylate, and azobisisobutyronitrile is 65:15:19:1;

[0055] 2. Carry out a free radical polymerization reaction at 75 °C for 7 h, and obtain a modified matrix resin after discharging;

[0056] 3. Add the modified matrix resin into diethylene glycol methyl ethyl ether, and stir at 55 °C for 1.5 h to obtain a resin solution;

[0057] 4. Mix carbon black and BYK-163 and then add them into the resin solution, and stir at 1000 rpm for 0.5 h;

[0058] 5. Add modified barium carbonate, BYK-346, dimethyl silicone oil, 2-n-octyl-4-isothiazolin-3-one, and triethanolamine into the resin solution, and adjust the pH to 8.5;

[0059] 6. Continue to stir the resin solution at 1000 rpm for 15 min, and filter it through a 0.5 μm filter element to obtain an inkjet printer weak solvent ink.

[0060] In the above steps 3 to 6, the mass ratio of the modified matrix resin, diethylene glycol methyl ethyl ether, modified barium carbonate, carbon black, BYK-163, BYK-346, dimethyl silicone oil, 2-n-octyl-4-isothiazolin-3-one, and triethanolamine is 25:48:10:11:1.5:0.8:0.6:0.5:2.6.

[0061] Example 2:

[0062] As Figure 2 shown, a preparation method of a weakly solvent ink for an inkjet printer includes the following steps:

[0063] 1. Add ethanol, 4-hydroxystyrene, 2-hydroxyethyl methacrylate, and lauroyl peroxide into a reaction kettle under nitrogen protection. The mass ratio of ethanol, 4-hydroxystyrene, 2-hydroxyethyl methacrylate, and lauroyl peroxide is 70:12:17.5:0.5;

[0064] 2. Carry out a free radical polymerization reaction at 80 °C for 6 h, and obtain a modified matrix resin after discharging;

[0065] 3. Add the modified matrix resin into diethylene glycol tetramethyl ether, and stir at 60 °C for 2 h to obtain a resin solution;

[0066] 4. Mix titanium dioxide and EFKA-4010 and then add them into the resin solution, and stir at 1200 rpm for 1 h;

[0067] 5. Add modified barium carbonate, BYK-348, polyoxyethylene polyoxypropylene glycerol ether, 1,2-benzisothiazolin-3-one, and N,N-dimethylethylamine into the resin solution, and adjust the pH to 8.8;

[0068] 6. Continue to stir the resin solution at 1200 rpm for 10 min, and filter it through a 0.5-μm filter element to obtain a weakly solvent ink for an inkjet printer.

[0069] In the above steps 3 to 6, the mass ratio of the modified matrix resin, diethylene glycol tetramethyl ether, modified barium carbonate, titanium dioxide, EFKA-4010, BYK-348, polyoxyethylene polyoxypropylene glycerol ether, 1,2-benzisothiazolin-3-one, and N,N-dimethylethylamine is 30:40:12:13:2:0.5:0.5:0.5:1.5.

[0070] Example 3:

[0071] As Figure 2 shown, a preparation method of a weakly solvent ink for an inkjet printer includes the following steps:

[0072] 1. Add ethanol, 4-hydroxystyrene, 2-hydroxyethyl methacrylate, and 2,2'-azobis(2-methylbutyronitrile) into a reaction kettle under nitrogen protection. The mass ratio of ethanol, 4-hydroxystyrene, 2-hydroxyethyl methacrylate, and 2,2'-azobis(2-methylbutyronitrile) is 62:15:22:1;

[0073] 2. Conduct a free radical polymerization reaction at 70 °C for 8 h. After discharging, a modified matrix resin is obtained;

[0074] 3. Add the modified matrix resin into methyl tert-butyl ether and stir at 50 °C for 1 h to obtain a resin solution;

[0075] 4. Mix quinacridone red and tributyl phosphate and then add them into the resin solution, and stir at 800 rpm for 0.75 h;

[0076] 5. Add modified barium carbonate, Capstone FS-3100, polyoxyethylene polyoxypropylene glycerol ether, 2-n-octyl-4-isothiazolin-3-one, and 2-amino-2-methyl-1-propanol into the resin solution, and adjust the pH to 9;

[0077] 6. Continue to stir the resin solution at 800 rpm for 20 min and filter it through a 0.5-μm filter element to obtain a weak solvent ink for inkjet printers.

[0078] In the above steps 3 to 6, the mass ratio of the modified matrix resin, methyl tert-butyl ether, modified barium carbonate, quinacridone red, tributyl phosphate, Capstone FS-3100, polyoxyethylene polyoxypropylene glycerol ether, 2-n-octyl-4-isothiazolin-3-one, and 2-amino-2-methyl-1-propanol is 25:45:15:9:1:0.8:0.7:0.5:3.

[0079] Example 4:

[0080] As Figure 2 shown, a preparation method of a weak solvent ink for an inkjet printer includes the following steps:

[0081] 1. Add ethanol, 4-hydroxystyrene, 2-hydroxyethyl methacrylate, and 2,2'-azobis(isobutyronitrile) into a reaction kettle under nitrogen protection. The mass ratio of ethanol, 4-hydroxystyrene, 2-hydroxyethyl methacrylate, and 2,2'-azobis(isobutyronitrile) is 66:12:21:1;

[0082] 2. Conduct a free radical polymerization reaction at 78 °C for 7.5 h. After discharging, a modified matrix resin is obtained;

[0083] 3. Add the modified matrix resin into diethylene glycol diethyl ether and stir at 55 °C for 1 h to obtain a resin solution;

[0084] 4. Mix benzimidazolone yellow and BYK-163 and add them to the resin solution, then stir at 1000 rpm for 0.5 h;

[0085] 5. Add modified barium carbonate, BYK-346, dimethyl silicone oil, 1,2-benzisothiazolin-3-one and triethanolamine to the resin solution, and adjust the pH to 8.3;

[0086] 6. Continue to stir the resin solution at 1000 rpm for 15 min and filter it through a 0.5-μm filter element to obtain the weak solvent ink for inkjet printers.

[0087] In the above steps 3-6, the mass ratio of the modified matrix resin, diethylene glycol diethyl ether, modified barium carbonate, benzimidazolone yellow, BYK-163, BYK-346, dimethyl silicone oil, 1,2-benzisothiazolin-3-one and triethanolamine is 24:46:14:12:1:0.5:0.5:0.5:1.5.

[0088] Example 5:

[0089] As Figure 2 shown, a preparation method of a weak solvent ink for inkjet printers includes the following steps:

[0090] 1. Add ethanol, 4-hydroxystyrene, 2-hydroxyethyl methacrylate and lauroyl peroxide to a reaction kettle under nitrogen protection. The mass ratio of ethanol, 4-hydroxystyrene, 2-hydroxyethyl methacrylate and lauroyl peroxide is 60:14.2:25:0.8;

[0091] 2. Carry out a free radical polymerization reaction at 72 °C for 7 h, and obtain the modified matrix resin after discharging;

[0092] 3. Add the modified matrix resin to diethylene glycol methyl ethyl ether and stir at 58 °C for 1.5 h to obtain a resin solution;

[0093] 4. Mix phthalocyanine blue and EFKA-4010 and add them to the resin solution, then stir at 900 rpm for 1 h;

[0094] 5. Add modified barium carbonate, BYK-348, polyoxyethylene polyoxypropylene glycerol ether, 2-n-octyl-4-isothiazolin-3-one and N,N-dimethyl ethylamine to the resin solution, and adjust the pH to 8.3;

[0095] 6. Continue to stir the resin solution at 1000 rpm for 15 min and filter it through a 0.5-μm filter element to obtain the weak solvent ink for inkjet printers.

[0096] In Steps 3 to 6 above, the mass ratio of the modified matrix resin, diethylene glycol methyl ethyl ether, modified barium carbonate, phthalocyanine blue, EFKA-4010, BYK-348, polyoxyethylene polyoxypropylene glycerol ether, 2-n-octyl-4-isothiazolin-3-one, and N,N-dimethyl ethylamine is 25:44:15:11:1.5:0.7:0.6:0.5:1.7.

[0097] Example 6:

[0098] As Figure 2 shown, a method for preparing a weakly solvent ink for an inkjet printer includes the following steps:

[0099] 1. Add ethanol, 4-hydroxystyrene, hydroxyethyl methacrylate, and azodiisooctanenitrile to a reaction kettle under nitrogen protection. The mass ratio of ethanol, 4-hydroxystyrene, hydroxyethyl methacrylate, and azodiisooctanenitrile is 63:17:19.5:0.5;

[0100] 2. Carry out a free radical polymerization reaction at 76 °C for 6.5 h, and obtain a modified matrix resin after discharging;

[0101] 3. Add the modified matrix resin to diethylene glycol tetramethyl ether, and stir at 53 °C for 1.2 h to obtain a resin solution;

[0102] 4. Mix titanium dioxide and tributyl phosphate and add them to the resin solution, and stir at 1100 rpm for 0.8 h;

[0103] 5. Add modified barium carbonate, Capstone FS-3100, dimethyl silicone oil, 1,2-benzisothiazolin-3-one, and 2-amino-2-methyl-1-propanol to the resin solution, and adjust the pH to 8.7;

[0104] 6. Continue to stir the resin solution at 1000 rpm for 15 min, and filter through a 0.5 μm filter element to obtain a weakly solvent ink for an inkjet printer.

[0105] In Steps 3 to 6 above, the mass ratio of the modified matrix resin, diethylene glycol tetramethyl ether, modified barium carbonate, titanium dioxide, tributyl phosphate, Capstone FS-3100, dimethyl silicone oil, 1,2-benzisothiazolin-3-one, and 2-amino-2-methyl-1-propanol is 26:48:11:10:1.5:0.6:0.4:0.5:2.

[0106] Comparative Example 1:

[0107] A method for preparing a weakly solvent ink for an inkjet printer includes the following steps:

[0108] 1. Add ethanol, styrene, 2-hydroxyethyl methacrylate, and azobisisobutyronitrile into a reaction kettle under nitrogen protection. The mass ratio of ethanol, styrene, 2-hydroxyethyl methacrylate, and azobisisobutyronitrile is 65:15:19:1.

[0109] 2. Conduct a free radical polymerization reaction at 75 °C for 7 h. After discharging, a modified matrix resin is obtained.

[0110] 3. Add the modified matrix resin into diethylene glycol methyl ethyl ether and stir at 55 °C for 1.5 h to obtain a resin solution.

[0111] 4. Mix carbon black and BYK-163 and then add them into the resin solution, and stir at 1000 rpm for 0.5 h.

[0112] 5. Add modified barium carbonate, BYK-346, dimethyl silicone oil, 2-n-octyl-4-isothiazolin-3-one, and triethanolamine into the resin solution, and adjust the pH to 8.5.

[0113] 6. Continue to stir the resin solution at 1000 rpm for 15 min and filter it through a 0.5-μm filter element to obtain the weak solvent ink for inkjet printers.

[0114] In the above steps 3-6, the mass ratio of the modified matrix resin, diethylene glycol methyl ethyl ether, modified barium carbonate, carbon black, BYK-163, BYK-346, dimethyl silicone oil, 2-n-octyl-4-isothiazolin-3-one, and triethanolamine is 25:48:10:11:1.5:0.8:0.6:0.5:2.6.

[0115] Comparative Example 2:

[0116] A preparation method of a weak solvent ink for inkjet printers, comprising the following steps:

[0117] 1. Add ethanol, 4-hydroxystyrene, ethyl methacrylate, and azodiisooctanenitrile into a reaction kettle under nitrogen protection. The mass ratio of ethanol, 4-hydroxystyrene, ethyl methacrylate, and azodiisooctanenitrile is 62:15:22:1.

[0118] 2. Conduct a free radical polymerization reaction at 70 °C for 8 h. After discharging, a modified matrix resin is obtained.

[0119] 3. Add the modified matrix resin into methyl tert-butyl ether and stir at 50 °C for 1 h to obtain a resin solution.

[0120] 4. Mix quinacridone red and tributyl phosphate and then add them into the resin solution, and stir at 800 rpm for 0.75 h.

[0121] 5. Add modified barium carbonate, Capstone FS-3100, polyoxyethylene polyoxypropylene glycerol ether, 2-n-octyl-4-isothiazolin-3-one and 2-amino-2-methyl-1-propanol to the resin solution, and adjust the pH to 9;

[0122] 6. Continuously stir the resin solution at 800 rpm for 20 min and filter it through a 0.5-μm filter element to obtain the weak solvent ink for inkjet printers.

[0123] In the above steps 3-6, the mass ratio of the modified matrix resin, methyl tert-butyl ether, modified barium carbonate, quinacridone red, tributyl phosphate, Capstone FS-3100, polyoxyethylene polyoxypropylene glycerol ether, 2-n-octyl-4-isothiazolin-3-one and 2-amino-2-methyl-1-propanol is 25:45:15:9:1:0.8:0.7:0.5:3.

[0124] Comparative Example 3:

[0125] A preparation method of a weak solvent ink for inkjet printers, comprising the following steps:

[0126] 1. Add ethanol, styrene, ethyl methacrylate and 2,2'-azobis(2,4-dimethylpentanenitrile) to a reaction kettle under nitrogen protection. The mass ratio of ethanol, styrene, ethyl methacrylate and 2,2'-azobis(2,4-dimethylpentanenitrile) is 63:17:19.5:0.5;

[0127] 2. Carry out a free radical polymerization reaction at 76 °C for 6.5 h, and obtain the modified matrix resin after discharging;

[0128] 3. Add the modified matrix resin to diethylene glycol tetramethyl ether and stir at 53 °C for 1.2 h to obtain a resin solution;

[0129] 4. Mix titanium dioxide and tributyl phosphate and add them to the resin solution, and stir at 1100 rpm for 0.8 h;

[0130] 5. Add modified barium carbonate, Capstone FS-3100, dimethyl silicone oil, 1,2-benzisothiazolin-3-one and 2-amino-2-methyl-1-propanol to the resin solution, and adjust the pH to 8.7;

[0131] 6. Continuously stir the resin solution at 1000 rpm for 15 min and filter it through a 0.5-μm filter element to obtain the weak solvent ink for inkjet printers.

[0132] In the above steps 3 to 6, the mass ratio of the modified matrix resin, diethylene glycol dimethyl ether, modified barium carbonate, titanium dioxide, tributyl phosphate, Capstone FS-3100, dimethyl silicone oil, 1,2-benzisothiazolin-3-one and 2-amino-2-methyl-1-propanol is 26:48:11:10:1.5:0.6:0.4:0.5:2.

[0133] Comparative Example 4: (without barium carbonate)

[0134] A preparation method of a weak solvent ink for an inkjet printer, comprising the following steps:

[0135] 1. Add ethanol, 4-hydroxystyrene, 2-hydroxyethyl methacrylate and azobisisobutyronitrile into a reaction kettle under nitrogen protection. The mass ratio of ethanol, 4-hydroxystyrene, 2-hydroxyethyl methacrylate and azobisisobutyronitrile is 66:12:21:1;

[0136] 2. Carry out a free radical polymerization reaction at 78 °C for 7.5 h, and obtain the modified matrix resin after discharging;

[0137] 3. Add the modified matrix resin into diethylene glycol diethyl ether, and stir at 55 °C for 1 h to obtain a resin solution;

[0138] 4. Mix benzimidazolone yellow and BYK-163 and add them into the resin solution, and stir at 1000 rpm for 0.5 h;

[0139] 5. Add BYK-346, dimethyl silicone oil, 1,2-benzisothiazolin-3-one and triethanolamine into the resin solution, and adjust the pH to 8.3;

[0140] 6. Continue to stir the resin solution at 1000 rpm for 15 min, and filter through a 0.5 μm filter element to obtain the weak solvent ink for an inkjet printer.

[0141] In the above steps 3 to 6, the mass ratio of the modified matrix resin, diethylene glycol diethyl ether, benzimidazolone yellow, BYK-163, BYK-346, dimethyl silicone oil, 1,2-benzisothiazolin-3-one and triethanolamine is 34:50:12:1:0.5:0.5:0.5:1.5.

[0142] Test the redox potential of the weak solvent ink prepared in this application through an electrochemical workstation, and reflect the antioxidant property of the prepared weak solvent ink by the magnitude of the redox potential.

[0143] Referring to QB / T 5489-2020, the absorbance of the weakly solvent-based ink prepared in this application was measured before and after centrifugation (3000 rpm / min, 10 min) by a sedimentation stability detection method, and its specific absorbance was calculated. The stability was reflected by the value of the specific absorbance.

[0144] Table 1 Test results of the weakly solvent-based ink for inkjet printers prepared in the examples and comparative examples

[0145]

[0146]

[0147] As can be seen from Table 1, the redox potential and specific absorbance of Examples 1-6 are better than those of Comparative Examples 1-3.

[0148] The reason is that in Examples 1-6, 4-hydroxystyrene and 2-hydroxyethyl methacrylate were subjected to free radical polymerization to prepare a modified matrix resin with phenolic hydroxyl groups and hydroxyl groups connected to the main chain of the molecule. The phenolic hydroxyl group can provide hydrogen atoms to combine with free radicals such as peroxy radicals ROO· and alkoxy radicals RO· generated in the ink or the environment, convert them into stable non-free radical products, and at the same time generate stable phenoxy radicals by itself, thereby interrupting the oxidation chain reaction. Therefore, it is not necessary to add an antioxidant to prevent the oxidation and deterioration of the ink components, endowing the ink with strong antioxidant ability, and at the same time avoiding the problems such as sedimentation, stratification or volatilization that may occur due to the difficult-to-guarantee compatibility of the externally added antioxidant with other components in the ink system, enhancing the stability of the ink. Moreover, the addition of modified barium carbonate can buffer the acidic components in the ink system, further enhancing the stability and antioxidant properties of the ink. In addition, the resin polymer chains generated by polymerization will form a physical crosslinking network after film formation, blocking the penetration of oxygen and moisture, delaying the photo-oxygen aging of the ink, and further improving the antioxidant properties of the ink. In addition, the presence of hydroxyl groups can cause hydrogen bonds or covalent bonds to be generated on the surface of the ink and a specific substrate (such as paper) to be sprayed. On the one hand, the adhesion of the ink on the surface of the specific substrate (such as paper) is enhanced; on the other hand, the polarity of the hydroxyl group can also enhance the compatibility between the modified matrix resin and the solvent used in this application, further enhancing the stability of the ink.

[0149] In Comparative Example 1, 4-hydroxystyrene and 2-hydroxyethyl methacrylate were not used for polymerization, but styrene without phenolic hydroxyl groups was used instead. Therefore, it is difficult to provide hydrogen atoms to combine with free radicals generated in the ink or the environment, and the antioxidant property of the ink decreases significantly. At the same time, the benzene ring without phenolic hydroxyl groups has relatively poor polarity, resulting in poor compatibility between the resin and the solvent, and ultimately the stability of the ink also decreases accordingly. In Comparative Example 2, 2-hydroxyethyl methacrylate and 4-hydroxystyrene were not used for polymerization, but ethyl methacrylate without hydroxyl groups was used instead. Therefore, the compatibility between the resin and the solvent decreases, and the film-forming property is also weakened. Eventually, the antioxidant property of the ink also decreases to some extent. In Comparative Example 3, styrene without phenolic hydroxyl groups and ethyl methacrylate without hydroxyl groups were used. Based on the same reasons as in Comparative Example 1 and Comparative Example 2, the antioxidant property and stability of the final ink are the worst. In addition, in Comparative Example 4, modified barium carbonate was not added. Therefore, it is difficult to buffer the acidic components in the ink system, and the stability and antioxidant property of the final ink are also poor.

[0150] The above results show and describe the basic principles, main features and advantages of the present application.

[0151] Those skilled in the art should understand that the present application is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principle of the present application. Without departing from the spirit and scope of the present application, the present application will have various changes and improvements, and these changes and improvements all fall within the scope of the present application claimed. The scope of protection claimed by the present application is defined by the equivalents of the appended claims.

Claims

1. A weak solvent ink for an inkjet printer, characterized in that: The invention comprises a modified matrix resin, a solvent, a modified barium carbonate, a pigment, a dispersant, a wetting agent, a defoaming agent, an antibacterial agent and a pH regulator; the modified matrix resin is obtained by free radical polymerization of 4-hydroxystyrene and hydroxyethyl methacrylate.

2. The eco-solvent ink for inkjet printer according to claim 1, characterized in that: The structure of the modified base resin comprises: Here, n is an integer between 10 and 50.

3. The eco-solvent ink for inkjet printer according to claim 1, characterized in that: The mass ratio of the modified base resin, solvent, modified barium carbonate, pigment, dispersant, wetting agent, defoamer, antibacterial agent and pH regulator is (20-35): (40-50): (10-20): (8-15): (1-2): (0.5-1): (0.5-1): (0.5-1): (1-3); The preparation method of the modified barium carbonate comprises: At 60-80°C, add the carbonate solution to the barium salt solution while stirring, and add the titanate coupling agent at the same time, and control the dripping rate to maintain the pH at 8-10; Continue stirring for 30 to 60 minutes, collect the solid by filtration, and wash the obtained solid with deionized water and anhydrous ethanol two to three times respectively; The cleaned solid is vacuum dried at 60-80°C for 4-8h, and crushed through a 200-mesh sieve to obtain modified barium carbonate.

4. The eco-solvent ink for inkjet printer according to claim 1, characterized in that: The solvent includes at least one of diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, diethylene glycol tetramethyl ether and methyl tert-butyl ether.

5. The eco-solvent ink for inkjet printer according to claim 1, characterized in that: The pigment includes any one of carbon black, titanium dioxide, phthalocyanine blue, quinacridone red and benzimidazolone yellow.

6. The eco-solvent ink for inkjet printer according to claim 1, characterized in that: The pH adjuster includes any one of N,N-dimethylethylamine, triethanolamine and 2-amino-2-methyl-1-propanol.

7. The method for preparing a weak solvent ink for an inkjet printer according to any one of claims 1 to 6, characterized in that: The following steps are involved: Add ethanol, 4-hydroxystyrene, hydroxyethyl methacrylate and initiator into a reaction kettle protected by nitrogen; The material in the reaction kettle undergoes a free radical polymerization reaction at a first temperature for a first time, and a modified matrix resin is obtained after the material is discharged; adding the modified base resin to the solvent and stirring at a second temperature for a second time to obtain a resin solution; adding the pigment and the dispersant to the resin solution and stirring the mixture at the first speed for a third time; Adding modified barium carbonate, a wetting agent, a defoaming agent, an antibacterial agent and a pH regulator to the resin solution to adjust the pH to a predetermined range; The resin solution is continuously stirred at the first rotation speed for a fourth time, and filtered through a 0.5 μm filter element to obtain a weak solvent ink for an inkjet printer.

8. The method for preparing a weak solvent ink for an inkjet printer according to claim 7, characterized in that: The mass ratio of the ethanol, 4-hydroxystyrene, hydroxyethyl methacrylate and the initiator is (60-70): (10-20): (15-25): (0.5-1).

9. The method for preparing a weak solvent ink for an inkjet printer according to claim 7, characterized in that: The initiator includes at least one of azobisisobutyronitrile, azobisisoheptanenitrile and lauroyl peroxide.

10. The method for preparing a weak solvent ink for an inkjet printer according to claim 7, characterized in that: The first temperature is 70-80°C, the second temperature is 50-60°C; the first time is 6-8h, the second time is 1-2h, the third time is 0.5-1h, and the fourth time is 10-20min; the first rotation speed is 800-1200rpm; and the predetermined pH range is 8-9.

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