Fading-resistant printing ink and preparation method thereof

Abstract

The invention relates to anti-fading printing ink and a preparation method thereof, and belongs to the technical field of ink. The ink comprises the following components in percentage by weight: 22-35% of inert pigment, 8-13% of a covering agent, 18-25% of varnish, 0.15-0.2% of a defoaming agent, 0.3-0.5% of a flatting agent and the balance of a connecting material, according to the inert pigment, a metal-based pigment is used as a color generation material, active amino groups of 1-chloropropanol and tetramethyl piperidylamine are subjected to a substitution reaction, methacryloyl chloride and alcoholic hydroxyl groups are esterified to prepare a modified monomer, a liquid phase suspension method and methyl methacrylate are adopted for copolymerization to coat the metal-based pigment, the coating rate of in-situ copolymerization is high, and the coating effect is good. The coating layer is good in transparency, and the hindered amine structure introduced by copolymerization of the modified monomer has excellent light stability, so that the yellowing property of the coating layer is greatly reduced, the influence on the color generation effect of the ink is reduced, and the ink shows excellent fading resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of inks, and specifically, relates to an anti-fading printing ink and a preparation method thereof. Background Art

[0002] Ink is a substance used to form graphic information during the printing process, which directly determines the tone, color, and clarity of the image on the printed matter, so it plays a huge role in the printing process. Generally, printing ink mainly consists of a binder, a colorant, a filler, and other additives; among them, the binder is a sticky fluid that serves as the carrier of the colorant and mainly functions to bond the colorant to form a film, while the colorant is the color-forming material of the ink, and its stability directly determines the printing color-forming effect of the ink.

[0003] Fading of printed matter refers to the deviation of the color of the printed pattern from the initial printed color, which is one of the important indicators for evaluating the quality of printed matter. The main reason for the fading of printed matter is the deterioration of the colorant, which leads to a change in its own properties, resulting in a color change. For example, iron oxide red without crystal water is bright iron red, and with crystal water it is yellowish. Therefore, to improve the anti-fading performance of ink, it is mainly to maintain the stability of the colorant. In the prior art, there are mainly two effective solutions to the problem of ink fading. One is to use chemical synthesis technology to develop colorants with stable properties. The limitation of this method is large, and it can only be replaced by similarity, and the color-forming effect of the existing colorant cannot be retained. The other is to coat the existing colorant to isolate the colorant from the external environment and maintain its stable performance. For example, Chinese Patent Application No. 202111033179.7 discloses that acrylate is used to coat the colorant to form microcapsules to improve the stability of the colorant; however, the carbonyl ester structure in the acrylate polymerization is prone to yellowing under sunlight, resulting in deviation of the light absorption and emission performance of the colorant, and thus generating color difference. Summary of the Invention

[0004] In order to solve the technical problems mentioned in the background art, the purpose of the present invention is to provide an anti-fading printing ink and a preparation method thereof.

[0005] The purpose of the present invention can be achieved by the following technical solutions: An anti-fading printing ink, by weight percentage, includes: 22 - 35% of inert pigment, 8 - 13% of covering agent, 18 - 25% of ink oil, 0.15 - 0.2% of defoaming agent, and 0.3 - 0.5% of leveling agent, and the balance is binder; Further, the binder is selected from modified polyurethane binder, which has good tolerance and anti-yellowing performance after film formation.

[0006] Further, the covering agent is selected from ultrafine titanium dioxide, which improves the covering property and color-forming performance of the ink.

[0007] Furthermore, the room temperature viscosity of the ink oil is not higher than 30 s.

[0008] The inert pigment is prepared by the following method: Step 1: Mix tetramethylpiperidineamine, triethylamine and tetrahydrofuran, introduce nitrogen for protection, heat up to 65 - 75 °C, apply mechanical stirring at 80 - 120 rpm, slowly add 1-chloropropanol, and continue the constant temperature reflux reaction after complete addition. Control the total addition reaction time of 1-chloropropanol to be 2 - 3 h. After the reaction is completed, rotary evaporate to remove tetrahydrofuran to obtain an intermediate; Furthermore, the dosage ratio of tetramethylpiperidineamine, 1-chloropropanol, triethylamine and tetrahydrofuran is 0.1 mol: 0.3 mol: 8 - 11 mL: 90 - 120 mL. Using triethylamine as an acid-binding agent to promote the active amino substitution reaction between 1-chloropropanol and tetramethylpiperidineamine.

[0009] Step 2: Mix the intermediate and dimethylacetamide evenly, control the temperature at 5 - 10 °C in an ice-water bath, apply mechanical stirring at 180 - 240 rpm, slowly add methacryloyl chloride, control the total addition reaction time of methacryloyl chloride to be 1.5 - 2 h. After the reaction is completed, wash with water and remove the aqueous phase, and dry under vacuum to obtain a modified monomer; Furthermore, the dosage ratio of the intermediate, methacryloyl chloride and dimethylacetamide is 0.1 mol: 0.31 - 0.32 mol: 50 - 60 mL. In a low-temperature environment, the highly active methacryloyl chloride undergoes an esterification reaction with the hydroxyl group introduced in the intermediate to introduce an acrylate structure for modification.

[0010] Step 3: Ultrasonically disperse methyl methacrylate, the modified monomer, the metal-based pigment, the emulsifier and deionized water, heat up to 70 - 80 °C, ultrasonically disperse again, slowly add an ammonium persulfate solution, control the addition reaction time of ammonium persulfate to be 1 - 1.3 h. After the reaction is completed, spray dry to obtain the inert pigment; Furthermore, the dosage ratio of the metal-based pigment, methyl methacrylate, the modified monomer, ammonium persulfate, the emulsifier and deionized water is 100 g: 45 - 60 mmol: 10 - 15 mmol: 0.1 - 0.15 g: 4 - 6 g: 360 - 430 mL. The nitrogen-oxygen structure in the modified monomer chelates with the metal-based pigment and adheres to its surface, and then copolymerizes with methyl methacrylate on the surface under the initiation of ammonium persulfate to coat the metal-based pigment.

[0011] A preparation method of a fade-resistant printing ink, and the specific operation is as follows: Premix the binder, the ink oil, the defoamer and the leveling agent under dry nitrogen protection, and then add the inert pigment and the covering agent and stir and disperse at high speed, and perform vacuum defoaming treatment to obtain the fade-resistant printing ink.

[0012] The beneficial effects of the present invention: The present invention uses a methacrylate copolymer to coat existing metal-based pigments to make inert pigments as color-forming materials. Through the active amino substitution reaction of 1-chloropropanol and tetramethylpiperidineamine, alcohol hydroxyl groups are introduced, and then methacryloyl chloride is esterified with the alcohol hydroxyl groups to graft and modify the methacrylate structure. The liquid-phase suspension copolymerization process is used to coat the metal-based pigments. The nitroxide structure introduced in the modified monomer preferentially binds to the metal-based pigments through chelation, and then copolymerizes in situ with methyl methacrylate on the surface of the metal-based pigments under the initiation of ammonium persulfate to form a polymer coating on the surface. Compared with traditional coated pigments, the coating layer formed by in-situ copolymerization has a higher coating rate, better protective performance for the pigments, and the coating layer based on the methacrylate copolymer matrix has high transparency, with little impact on the color-forming effect of the pigments themselves. In addition, the hindered amine structure introduced by the copolymerization of the modified monomer has excellent light stability, greatly reducing the yellowing of the coating layer and alleviating the impact on the color-forming effect of the ink, making the ink exhibit excellent anti-fading performance. Specific Embodiments

[0013] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0014] Specific Embodiment 1, preparing anti-fading printing ink, specifically as follows: 1) Preparation of inert pigments Step 1: Mix tetramethylpiperidineamine, triethylamine and tetrahydrofuran, introduce nitrogen protection, heat up to 75 °C, apply mechanical stirring at 120 rpm, and slowly add 1-chloropropanol within 40 minutes. After complete addition, continue the constant-temperature reflux reaction, and control the total addition reaction time of 1-chloropropanol to be 2 h. During the reaction, the dosage ratio of tetramethylpiperidineamine, 1-chloropropanol, triethylamine and tetrahydrofuran is 0.1 mol: 0.3 mol: 11 mL: 120 mL. After the reaction, rotary evaporation is used to remove tetrahydrofuran to obtain an intermediate.

[0015] Step 2: Mix the intermediate and dimethylacetamide evenly, control the temperature at 10 °C in an ice-water bath, apply mechanical stirring at 240 rpm, and slowly add methacryloyl chloride within 30 minutes. Control the total addition reaction time of methacryloyl chloride to be 1.5 h. During the reaction, the dosage ratio of the intermediate, methacryloyl chloride and dimethylacetamide is 0.1 mol: 0.32 mol: 60 mL. After the reaction, wash with water and remove the aqueous phase, and then vacuum dry to obtain a modified monomer.

[0016] Step 3: Take methyl methacrylate, modified monomer, metal-based pigment, emulsifier and deionized water, and disperse them by ultrasonic wave at 33 kHz for 10 min. Among them, in the examples, in order to facilitate detection, 190A type iron oxide red is used as the metal-based pigment, and AP470Z type emulsifier is used as the emulsifier. Then, heat up to 80 °C, disperse again by ultrasonic wave at 25 kHz, and slowly add a saturated aqueous solution of ammonium persulfate within 10 min. Control the addition reaction time of ammonium persulfate to be 1 h. During the reaction, the dosage ratio of metal-based pigment, methyl methacrylate, modified monomer, ammonium persulfate, emulsifier and deionized water is 100 g: 45 mmol: 15 mmol: 0.15 g: 6 g: 430 mL. After the reaction, spray drying is carried out to obtain an inert pigment.

[0017] 2) Prepare anti-fading printing ink Take raw materials according to weight percentage: 35% of inert pigment, prepared by this example; 8% of covering agent, and ultrafine titanium dioxide is used in the implementation process, with a particle size of about 0.3 μm; 25% of ink oil, and ST-1001A type raw materials are used in the implementation process, and the room temperature viscosity is about 25 s; 0.2% of defoamer, and Dehydran1620 type raw materials are used in the implementation process; 0.5% of leveling agent, and SH-450 type raw materials are used in the implementation process; 31.3% of binder, and WANCOL® 901H type modified polyurethane binder is used in the implementation process; Put the binder, ink oil, defoamer and leveling agent under the protection of dry nitrogen, premix at 120 rpm for 10 min, then add the inert pigment and covering agent, and stir and disperse at high speed of 600 rpm for 20 min. After vacuum degassing treatment, anti-fading printing ink is obtained.

[0018] Specific embodiment 2, prepare anti-fading printing ink, specifically as follows: 1) Prepare inert pigment Step 1: Take tetramethylpiperidinamine, triethylamine and tetrahydrofuran and mix them, introduce nitrogen protection, heat up to 65 °C, apply mechanical stirring at 80 rpm, and slowly add 1-chloropropanol within 1 h. After complete addition, continue the constant temperature reflux reaction, and control the total addition reaction time of 1-chloropropanol to be 3 h. During the reaction, the dosage ratio of tetramethylpiperidinamine, 1-chloropropanol, triethylamine and tetrahydrofuran is 0.1 mol: 0.3 mol: 8 mL: 90 mL. After the reaction, rotary evaporation is carried out to remove tetrahydrofuran to obtain an intermediate.

[0019] Step 2: Mix the intermediate and dimethylacetamide evenly, control the temperature at 5 °C in an ice-water bath, apply mechanical stirring at 180 rpm, slowly add methacryloyl chloride within 50 min, and control the total addition reaction time of methacryloyl chloride to be 2 h. During the reaction, the dosage ratio of the intermediate, methacryloyl chloride and dimethylacetamide is 0.1 mol: 0.31 mol: 50 mL. After the reaction, wash with water and remove the aqueous phase, and then dry under vacuum to obtain the modified monomer.

[0020] Step 3: Take methyl methacrylate, the modified monomer, metal-based pigment, emulsifier and deionized water, disperse them by ultrasonic wave at 33 kHz for 10 min, then heat up to 70 °C, and disperse them by ultrasonic wave again at 25 kHz. Slowly add a saturated aqueous solution of ammonium persulfate within 15 min, and control the addition reaction time of ammonium persulfate to be 1.3 h. During the reaction, the dosage ratio of the metal-based pigment, methyl methacrylate, the modified monomer, ammonium persulfate, emulsifier and deionized water is 100 g: 55 mmol: 12 mmol: 0.12 g: 5 g: 360 mL. After the reaction, spray dry to obtain the inert pigment.

[0021] 2) Prepare the anti-fading printing ink Take raw materials according to weight percentage: 28% of inert pigment, prepared by this example; 11% of covering agent, 22% of ink oil, 0.18% of defoaming agent, 0.4% of leveling agent, 38.42% of binder; Feed the binder, ink oil, defoaming agent and leveling agent under the protection of dry nitrogen, premix at 120 rpm for 10 min, then add the inert pigment and covering agent and stir and disperse at high speed of 600 rpm for 20 min, and obtain the anti-fading printing ink after vacuum defoaming treatment.

[0022] Specific Embodiment 3, prepare the anti-fading printing ink, specifically as follows: 1) Prepare the inert pigment Step 1: Mix tetramethylpiperidinamine, triethylamine and tetrahydrofuran, introduce nitrogen protection, heat up to 72 °C, apply mechanical stirring at 120 rpm, slowly add 1-chloropropanol within 50 min, and continue the constant temperature reflux reaction after complete addition. Control the total addition reaction time of 1-chloropropanol to be 2.5 h. During the reaction, the dosage ratio of tetramethylpiperidinamine, 1-chloropropanol, triethylamine and tetrahydrofuran is 0.1 mol: 0.3 mol: 10 mL: 110 mL. After the reaction, rotary evaporate to remove tetrahydrofuran to obtain the intermediate.

[0023] Step 2: Take the intermediate and dimethylacetamide and mix them evenly. Control the temperature at 5°C in an ice-water bath, apply mechanical stirring at 240 rpm, and slowly add methacryloyl chloride within 40 min. Control the total addition reaction time of methacryloyl chloride to be 1.8 h. During the reaction, the dosage ratio of the intermediate, methacryloyl chloride, and dimethylacetamide is 0.1 mol: 0.31 mol: 55 mL. After the reaction, wash with water and remove the aqueous phase, and then dry under vacuum to obtain the modified monomer.

[0024] Step 3: Take methyl methacrylate, the modified monomer, metal-based pigment, emulsifier, and deionized water and disperse them by ultrasonic wave at 33 kHz for 10 min. Then heat up to 75°C and disperse again by ultrasonic wave at 25 kHz. Slowly add the saturated aqueous solution of ammonium persulfate within 15 min. Control the addition reaction time of ammonium persulfate to be 1.1 h. During the reaction, the dosage ratio of the metal-based pigment, methyl methacrylate, the modified monomer, ammonium persulfate, emulsifier, and deionized water is 100 g: 60 mmol: 10 mmol: 0.1 g: 4 g: 400 mL. After the reaction, spray dry to obtain the inert pigment.

[0025] 2) Prepare the anti-fading printing ink Take raw materials according to weight percentage: 22% of the inert pigment, prepared in this example; 13% of the covering agent, 18% of the ink oil, 0.15% of the defoaming agent, 0.3% of the leveling agent, and 46.55% of the binder; Charge the binder, ink oil, defoaming agent, and leveling agent under the protection of dry nitrogen, premix at 120 rpm for 10 min, and then add the inert pigment and the covering agent and stir and disperse at high speed at 600 rpm for 20 min. After vacuum defoaming treatment, obtain the anti-fading printing ink.

[0026] Comparative Example 1 This comparative example refers to Example 3. During the preparation of the ink, replace the inert pigment with iron oxide red pigment of the same weight, and simultaneously add 0.15% of the light stabilizer GW-508.

[0027] Comparative Example 2 This comparative example refers to Example 3. Use methyl methacrylate to coat iron oxide red to obtain the coated pigment, and use it to prepare the ink. The specific steps are as follows: Step D1: Ultrasonically disperse iron oxide red, ammonium persulfate, emulsifier, and deionized water, heat up to 80°C, stir at 360 rpm, and slowly add methyl methacrylate within 40 min. After complete addition, continue to stir and react at a constant temperature. Control the total addition reaction time of methyl methacrylate to be 1.5 h, and then spray dry. During the reaction, the dosage ratio of the metal-based pigment, methyl methacrylate, ammonium persulfate, emulsifier, and deionized water is 100 g: 70 mmol: 0.2 g: 5 g: 400 mL to obtain the coated filler; Step D2: Referring to Example 3, replace the inert pigment with the same weight of coated filler, and additionally add 0.15% of light stabilizer GW-508.

[0028] Print the ink prepared above on the surface of PVC spray cloth, and control the ink application amount to be 35 g / m 2 , leave Aster tataricus L. f. to stand and dry for 24 h to make specimens, which are respectively recorded as Test Specimens 1-3 and Comparative Specimens 1-2; Referring to the GB / T13217.7-2023 standard, use the cross-cut method to test the adhesion of the specimens; place the spray-painted specimens in an ultraviolet oven, control the temperature to be 60 °C, and the ultraviolet irradiation intensity to be 120 W / m 2 , process for 168 h to simulate the outdoor exposure environment; immerse the spray-painted specimens in 5% sodium carbonate solution and 1% sulfuric acid solution respectively to simulate the acid-base environment, soak for 12 h, then take them out and dry; use a spectrophotometric colorimeter to measure the color difference before and after the treatment; the specific test data are shown in Table 1: Table 1

[0029] It can be seen from the data in Table 1 that the ink prepared by the present invention has good adhesion, excellent lightfastness, acid and alkali fading resistance, and especially the lightfastness performance is significantly better than that of the comparative example.

[0030] In the description of the specification, the description referring to terms such as "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0031] The above content is only an example and illustration of the present invention. Those skilled in the art of the present technology make various modifications or supplements to the described specific embodiments or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined by the claims of the present invention, they should all belong to the protection scope of the present invention.

Claims

1. An anti-fading printing ink, characterized in that: Included by weight percentage: Inert pigment 22-35%, covering agent 8-13%, varnish 18-25%, defoamer 0.15-0.2% and leveling agent 0.3-0.5%, the rest is the connecting material; The inert pigment is prepared by the following method: Step 1: tetramethylpiperidinamine, triethylamine and tetrahydrofuran are mixed, nitrogen is introduced for protection, the temperature is raised to 65-75°C, 1-chloropropanol is slowly added while stirring, and the total reaction time of 1-chloropropanol is controlled to be 2-3h. After the reaction is completed, tetrahydrofuran is removed by rotary evaporation to obtain an intermediate; Step 2: Mix the intermediate and dimethylacetamide, control the temperature in an ice-water bath to 5-10°C, stir and slowly add methacryloyl chloride, and control the total reaction time of methacryloyl chloride to be 1.5-2h. After the reaction, wash with water and remove the water phase, and vacuum dry to obtain a modified monomer; Step 3: Ultrasonic dispersion of methyl methacrylate, modified monomer, metal-based pigment, emulsifier and deionized water, heating to 70-80°C, ultrasonic dispersion again, slowly adding ammonium persulfate solution, controlling the reaction time of adding ammonium persulfate to be 1-1.3h, spray drying after the reaction is completed, and obtaining an inert pigment.

2. The anti-fading printing ink according to claim 1, characterized in that: The usage ratio of tetramethylpiperidinamine, 1-chloropropanol, triethylamine and tetrahydrofuran is 0.1 mol: 0.3 mol: 8-11 mL: 90-120 mL.

3. The anti-fading printing ink according to claim 2, characterized in that: The usage ratio of the intermediate, methacryloyl chloride and dimethylacetamide is 0.1 mol: 0.31-0.32 mol: 50-60 mL.

4. The anti-fading printing ink according to claim 3, characterized in that: The usage ratio of the metal-based pigment, methyl methacrylate, modified monomer, ammonium persulfate, emulsifier and deionizer is 100g: 45-60mmol: 10-15mmol: 0.1-0.15g: 4-6g: 360-430mL.

5. The anti-fading printing ink according to claim 1, characterized in that: The connecting material is selected from modified polyurethane connecting materials.

6. The anti-fading printing ink according to claim 1, characterized in that: The covering agent is selected from ultrafine titanium dioxide.

7. The anti-fading printing ink according to claim 1, characterized in that: The room temperature viscosity of the varnish oil is not higher than 30s.

8. The method for preparing a fade-resistant printing ink according to claim 1, characterized in that: The specific operation is: premixing the binder, varnish, defoamer and leveling agent under the protection of dry nitrogen, then adding inert pigment and covering agent, stirring and dispersing, and vacuum degassing to obtain anti-fading printing ink.

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