A water-based pigment red PR122 ink, a preparation method and application thereof

Abstract

The present application belongs to the field of organic pigment water-based ink, and specifically discloses a water-based pigment red PR122 ink, a preparation method and application thereof. According to weight percentage, the raw material composition of the ink comprises: 30-50% of a modified pigment red PR122 pigment dispersion system with a hydrophilic group sodium carboxyl, 0.05-0.3% of an anionic dispersant, 1-3% of a non-ionic dispersant, 0.3-0.8% of an antifoaming agent, 5-10% of a polyhydric alcohol, 0.02-0.05% of a preservative and bactericide, and 36-63% of deionized water. The water-based pigment ink has bright color, high ink gloss, small pigment particles, and uniform and stable pigment paste dispersion. The prepared water-based pigment ink is used for the ink writing of a ballpoint pen refill, and has smooth writing, no nozzle blockage in the inkjet printing process, and good wetting performance, so that the ink can be well spread on the surface of cotton fabric without penetration.

Description

Technical Field

[0001] This invention belongs to the field of organic pigment water-based inks, and specifically discloses a water-based pigment red PR122 ink, its preparation method and application. Background Technology

[0002] Because water-based organic pigment inks do not contain highly volatile substances, they pose very little harm to human health and the environment, thus possessing significant development and application value and becoming a research hotspot in the ink field in recent years. Water-based inks are generally composed of pigment pastes, binders, dispersants, defoamers, humectants, and preservatives and bactericides. Among these, the performance of the pigment paste has a significant impact on the actual application effect of the ink.

[0003] Because organic pigments have low polarity and strong hydrophobicity, they are difficult to disperse uniformly and stably in water. Therefore, pigment pastes with good performance often require modification of organic pigments. Currently, most pigment pastes used in water-based ink formulations are prepared by directly adding dispersants or adding hydrophilic resins as water-based binders to change the surface polarity of the pigments.

[0004] The method of adding dispersants, such as Wang Ding et al., involves adding dispersant 2-naphthalenesulfonic acid formaldehyde polymer sodium salt, anti-settling agent polyurea polymer and N-methylpyrrolidone mixture, defoamer polydimethylsiloxane, and thickener white mineral oil to organic pigments to prepare water-based organic pigment ink pastes. The results show that the pigment paste obtained by this formulation is highly stable, with good color development and dyeing performance, and is suitable for water-based latex paints and water-based painting inks. Chen Duming, Song Xiushan et al. prepared water-based ultrafine pigment pastes using organic pigments, a mixture of ethylenediamine poly(oxyethylene)-poly(oxypropylene) ether surfactants and fatty alcohol polyoxyethylene ether surfactants, defoamers, and bactericides and preservatives as raw materials. The results show that the pigment ink in the prepared water-based pigment paste has improved room temperature stability and short-term stability at high temperatures, with fine pigment particle size, high viscosity stability, and good gloss, making it suitable for use in water-based inkjet printing inks. LVDJ et al. prepared water-based pigment pastes using Pigment Red 146, anionic dispersant acyl N-methyl taurate (Lgepon T), and nonionic dispersant Pingpingjia O-25 as raw materials. Their results showed that when 2% Lgenpon T and 4% nonionic dispersant O-25 were used as a compound dispersant to prepare the water-based pigment paste, the paste exhibited good stability and could be further used in water-based inks for printing and coatings. Xu Junqiang et al. prepared organic pigment pastes using SMA-polyoxyethylene ether-quaternary ammonium cationic polymeric dispersant, SMA-polyoxyethylene ether-amide cationic polymeric dispersant, organic red pigment, thickener, anti-settling agent, bactericide, and defoamer as raw materials. Their results indicated that the pigment paste prepared by this formulation had good storage stability and high tinting strength, and was widely used in textile printing and inkjet printing inks.

[0005] From the above formulations for preparing water-based ink color pastes using the surfactant addition method, the hydrophilicity of pigment particles is improved after adding dispersants. The prepared water-based pigment color pastes have good color and can be uniformly and stably dispersed, which can well meet the requirements of water-based ink applications for color pastes. However, during long-term storage, the color pastes prepared by the above formulations inevitably experience surfactant detachment from the surface of pigment particles, causing the pigment particles to re-aggregate into large particles, resulting in sedimentation of the color paste. To maintain the stability of the color paste, wetting agents and anti-settling agents are often added to the formulation. Furthermore, experiments have shown that when water-based ink color pastes are prepared directly with sodium dodecyl sulfate and Tween-80 as a compound dispersant and raw materials, some pigment particles still remain suspended on the surface of the resulting color paste, which does not meet the requirements of water-based ink applications.

[0006] The addition of hydrophilic resins is another method. For example, Li Mingfeng et al. prepared water-soluble hyperbranched dispersion resins using boric acid, triethylamine, vinyltrimethoxysilane, dimethoxychlorosilane, 2-buten-1,4-diol, and chlorosulfonic acid as raw materials. Subsequently, water-based ink pastes for ballpoint pens were prepared using the resin, pigments, humectants, bactericides, and lubricants. The results showed that the water-based ink pastes prepared with water-soluble hyperbranched dispersion resins exhibited good storage stability and high pigment adhesion, effectively solving the problem of pigment particle aggregation and sedimentation in the field of water-based ballpoint pen inks. Jiang Bo et al. prepared water-based ink pigment pastes using pigments, acrylic resin, water, humectants, and defoamers as raw materials and applied them to the field of food and pharmaceutical packaging printing inks. The results showed that adding 30% acrylic resin by weight of the total ink mass as a water-based binder resulted in a uniformly and stably dispersed water-based ink paste with pigment particle sizes reaching 15 μm.

[0007] As can be seen from the above method of preparing pigment pastes for water-based inks using hydrophilic resin binders, the resulting pigment pastes exhibit good storage stability and high pigment adhesion. However, because hydrophilic resins generally have high viscosity, they easily encapsulate organic pigments, resulting in larger particle sizes and consequently, higher viscosity water-based ink pastes. Furthermore, after prolonged storage, the water-based resin can detach from the pigment surface, causing ink sedimentation.

[0008] Besides directly adding dispersants and hydrophilic resins, some researchers are also using pigment-modified color pastes to prepare water-based inks. For example, Wen Mingchu et al. used p-aminobenzenesulfonic acid, Pigment Red 122, and sodium nitrite as raw materials to prepare Pigment Red 122 water-based color paste via a diazonium salt reaction, and applied it to the field of water-based inks for ballpoint pens. The results showed that the color paste prepared by this method had low particle size and uniform dispersion, and when applied to water-based ballpoint pen inks, there was no ink breakage phenomenon when drawing a line of 400m. Xu Zhenxiang et al. first prepared amino-terminated Pigment Orange 13 using 2-(3,5-difluorophenyl)-5-methyl-2,4-dihydro-3H-pyrazole-3-one, 3,3-dichlorobenzidine, and sodium nitrite as raw materials. Subsequently, they prepared organic pigments for inks using amino-terminated Pigment Orange 13, 3,3,4,4-dimethylbenzyl ketone tetracarboxylic dianhydride, and a mixture of acetic anhydride-methylpyridine as raw materials. The results showed that the modified pigments exhibited improved solvent resistance, high-temperature resistance, and acid and alkali resistance.

[0009] As can be seen from the preparation of inks using pigment modification methods, modified pigment pastes possess advantages such as low particle size, good dispersibility, high temperature resistance, solvent resistance, and acid and alkali resistance. However, existing modification methods still suffer from problems such as multiple reaction steps, complex reactions, and uncommon raw materials. Furthermore, the large amount of hydrochloric acid used in the reaction process corrodes production equipment, making it unsuitable for industrial production.

[0010] As can be seen from the above preparation of color pastes for water-based organic pigment inks, existing ink pigment color pastes still have some problems such as poor long-term stability, easy re-aggregation of particles, need for additional wetting agents and anti-settling agents, complex reactions, and difficulty in industrial production. Summary of the Invention

[0011] The purpose of this invention is to overcome the problems existing in the existing water-based ink pigment formulations pointed out in the background art, and to propose a water-based organic pigment ink formulation that has no overall color difference, excellent stability, does not require additional anti-settling agents, has a simple reaction, is suitable for industrial production, and can be directly applied to the fields of ballpoint pen water-based inks and inkjet printing.

[0012] To achieve the above objectives, the water-based organic pigment ink of the present invention comprises, by weight percentage, the following raw materials: 30%–50% of a pigment red PR122 modified pigment dispersion system with hydrophilic sodium carboxyl groups, 0.05%–0.3% of anionic dispersant, 1%–3% of nonionic dispersant, 0.3%–0.8% of defoamer, 5%–10% of polyol, 0.02%–0.05% of preservative and bactericide, and 36%–63% of deionized water.

[0013] The preparation steps for water-based organic pigment inks are as follows:

[0014] (1) The preparation process of the modified pigment Red 122 with hydrophilic sodium carboxyl groups is as follows:

[0015] In a four-necked flask equipped with a stirrer, thermometer, and constant-pressure dropping funnel, 120 mL of N,N-dimethylformamide, 6.8 g (0.02 mol) of Pigment Red 122, and 6.72 g (0.06 mol) of potassium tert-butoxide were added sequentially. The temperature was slowly raised to 95–105 °C and maintained for 5–6 h to ionize the pigment molecules on the surface. The color gradually changed from red to dark blue. When the dark blue color stopped deepening, 7.56 g (0.08 mol) of chloroacetic acid was slowly added, and the temperature was then raised to 115–125 °C and maintained for 5 h. The color of the system gradually returned to that of Pigment Red PR122, and hydrophilic groups were grafted onto the pigment molecules. The mixture was washed with deionized water and filtered to obtain a filter cake to remove impurities and residual solvent. The pigment filter cake with grafted hydrophilic groups was then added to deionized water and stirred to disperse. After dispersion, an appropriate amount of sodium hydroxide was added to adjust the pH value of the pigment paste to around 9-10, thus obtaining a modified pigment red PR122 dispersion system with hydrophilic sodium carboxyl groups.

[0016] (2) Add the anionic dispersant sodium dodecyl sulfate and the nonionic dispersant Tween-80 to the pigment red PR122 modified pigment dispersion system with hydrophilic sodium carboxylate prepared in step (1), and stir to mix evenly to prepare a pigment mixture.

[0017] The amount of anionic dispersant sodium dodecyl sulfate is 0.05% to 0.3% of the total mass of pigment ink, the amount of nonionic dispersant Tween-80 is 1% to 3% of the total mass of pigment ink, and the amount of pigment red PR122 modified pigment dispersion system with hydrophilic sodium carboxylate is 30% to 50% of the total mass of pigment ink.

[0018] Preferably, the amount of anionic dispersant is 0.1% to 0.15% of the total mass of the pigment ink, the amount of nonionic dispersant is 1.5% to 2.5% of the total mass of the pigment ink, and the amount of Pigment Red PR122 modified pigment dispersion system with hydrophilic sodium carboxylate is 35% to 45% of the total mass of the pigment ink.

[0019] (3) Add polyol and preservative and bactericide to pigment mixture, stir and disperse to prepare pigment pre-color paste; add defoamer to pigment pre-color paste, and add a certain amount of deionized water to adjust the proportion of each substance in color paste to prepare pigment color paste; transfer pigment color paste to high-speed homogenizer for homogenization and dispersion to prepare water-based organic pigment ink.

[0020] The polyol is one or more of ethylene glycol, propylene glycol or glycerol, and its dosage is 5% to 10% of the total mass of the pigment ink. The preservative and bactericide is sodium benzoate, and its dosage is 0.02% to 0.05% of the total mass of the pigment ink.

[0021] Preferably, the polyol is glycerol, which accounts for 6% to 8% of the total mass of the pigment ink, and the amount of sodium benzoate is 0.025% to 0.035% of the total mass of the pigment ink.

[0022] The defoamer is TF-906 type defoamer, and the dosage is 0.3% to 0.8% of the total mass of pigment ink. The homogenization speed of the high-speed homogenizer is 15,000 to 18,000 r / min, and the homogenization time is 15 to 25 min.

[0023] Preferably, the amount of defoamer is 0.5% to 0.6% of the total mass of pigment ink, the homogenization speed of the high-speed homogenizer is 16,000 to 17,500 r / min, and the homogenization time is 18 to 22 min.

[0024] The resulting water-based pigment ink has a particle size of less than 500 nm and a viscosity of 2–5 cP.

[0025] Beneficial effects: This invention uses a pigment red PR122 modified pigment dispersion system with hydrophilic sodium carboxylate groups to prepare water-based pigment inks, which effectively improves the problems of pigment agglomeration during storage, poor ink stability, and large pigment particle size in existing water-based ink formulations. Attached image description:

[0026] Figure 1 Comparison of infrared spectra of Pigment Red 122 before and after modification with chloroacetic acid. Detailed Implementation

[0027] The present application is illustrated below with reference to specific embodiments. However, these embodiments are given as examples only and are not considered as all the technical solutions of the present invention, nor are they a limitation on the overall technical solution of the present invention. Any simple changes or substitutions to the same or similar technical features are within the protection scope of the present invention.

[0028] Example 1

[0029] In a 250 mL four-necked flask equipped with a stirrer, thermometer, and constant-pressure dropping funnel, 6.8 g (0.02 mol) of Pigment Red 122, 6.72 g (0.06 mol) of potassium tert-butoxide, and 120 mL of N,N-dimethylformamide were added sequentially. The reaction was maintained at 95–105 °C for 6 hours, after which the reaction solution turned completely blue. Then, 7.56 g (0.08 mol) of chloroacetic acid was slowly added dropwise, and the reaction was maintained at 115–125 °C for 12 hours. After the reaction was completed, 60 mL of deionized water was added to wash away impurities and residual solvent, and the mixture was filtered to obtain a filter cake. The obtained filter cake was dispersed in 110 mL of deionized water, and 1.6 g of sodium hydroxide was added to adjust the pH to 9–10, thus preparing 120 g of Pigment Red PR122 modified pigment dispersion system with hydrophilic sodium carboxyl groups.

[0030] Example 2

[0031] Take 10g of the modified pigment dispersion with hydrophilic sodium carboxylate groups prepared in Example 1, place it in a 50mL beaker, and add 0.025g of anionic dispersant sodium dodecyl sulfate and 0.5g of nonionic dispersant Tween-80 sequentially. Stir until homogeneous to obtain a pigment paste mixture. Subsequently, add 1.5g of glycerol and 0.08g of sodium benzoate to the above mixture, and stir to obtain an aqueous pigment pre-paste. Finally, transfer the above pigment pre-paste to a high-speed homogenizer, add 0.15g of TF-906 defoamer, and add deionized water until the total mass of the pigment paste reaches 25g. Homogenize it at 17000r / min for 20min to obtain the final aqueous pigment ink. The viscosity of the obtained pigment ink is measured to be 2.05cP, the particle size is 290nm, and the specific absorbance reaches 93% after centrifugation at 4000r / min for 20min. Its performance meets the requirements of continuous inkjet printing technology, which specifies an ink viscosity of 2–5 cP and an average pigment particle size of less than 0.5 μm. When used in inkjet printing, the ink paste causes no nozzle clogging and no seepage into cotton fabrics. When used with water-based inks for ballpoint pens, it writes for 400 meters without interruption of ink flow.

[0032] Example 3

[0033] Take 20g of the modified pigment dispersion with hydrophilic sodium carboxylate groups prepared in Example 1, place it in a 100mL beaker, and add 0.05g of anionic dispersant sodium dodecyl sulfate and 1.0g of nonionic dispersant Tween-80 sequentially. Stir until homogeneous to obtain a pigment paste mixture. Subsequently, add 4.0g of glycerol and 0.16g of sodium benzoate to the above mixture, and stir to obtain an aqueous pigment pre-paste. Finally, transfer the above pigment pre-paste to a high-speed homogenizer, add 0.30g of TF-906 defoamer, and add deionized water until the total mass of the pigment paste reaches 50g. Homogenize it at 15000r / min for 20min to obtain the final aqueous pigment ink. The viscosity of the obtained pigment ink is measured to be 2.55cP, the particle size is 450nm, and the specific absorbance reaches 88% after centrifugation at 4000r / min for 20min. Its performance meets the requirements of continuous inkjet printing technology, which specifies an ink viscosity of 2–5 cP and an average pigment particle size of less than 0.5 μm. When used in inkjet printing, the ink paste causes no nozzle clogging and no seepage into cotton fabrics. When used with water-based inks for ballpoint pens, it writes for 350 meters without ink interruption.

[0034] Example 4

[0035] 10g of the modified pigment dispersion with hydrophilic sodium carboxylate groups prepared in Example 1 was placed in a 50mL beaker, and 0.025g of anionic dispersant sodium dodecyl sulfate and 0.5g of nonionic dispersant Tween-80 were added sequentially. The mixture was stirred until homogeneous to obtain a pigment paste mixture. Subsequently, 2.8g of glycerol and 0.08g of sodium benzoate were added to the mixture, and after stirring, an aqueous pre-pigment paste was obtained. Finally, the pre-pigment paste was transferred to a high-speed homogenizer, and 0.15g of TF-906 defoamer was added, along with deionized water until the total mass of the pigment paste reached 25g. The homogenizer was homogenized for 20min at 16000r / min to obtain the final aqueous pigment ink. The viscosity of the obtained pigment ink was measured to be 3.45cP, the particle size was 360nm, and the specific absorbance reached 90% after centrifugation at 4000r / min for 20min. Its performance meets the requirements of continuous inkjet printing technology, which specifies an ink viscosity of 2-5 cP and an average pigment particle size of less than 0.5 μm. The pigment paste does not clog the printhead during inkjet printing and exhibits no surface bleeding in cotton fabrics. When used with water-based inks for ballpoint pens, it writes for 400 meters without ink interruption. However, the relatively high amount of glycerol used slows down the ink drying speed, affecting both inkjet printing and ballpoint pen writing performance.

[0036] Example 5

[0037] 10g of the modified pigment dispersion with hydrophilic sodium carboxylate groups prepared in Example 1 was placed in a 50mL beaker, and 0.025g of anionic dispersant sodium dodecyl sulfate and 0.5g of nonionic dispersant Tween-80 were added sequentially. The mixture was stirred until homogeneous to obtain a pigment paste mixture. Subsequently, 1.5g of ethylene glycol and 0.08g of sodium benzoate were added to the mixture, and the mixture was stirred to obtain an aqueous pigment pre-paste. Finally, the pigment pre-paste was transferred to a high-speed homogenizer, and 0.15g of TF-906 defoamer was added, along with deionized water until the total mass of the pigment paste reached 25g. The homogenizer was homogenized for 20min at 17000r / min to obtain the final aqueous pigment ink. The viscosity of the obtained pigment ink was measured to be 2.01cP, the particle size was 285nm, and the specific absorbance reached 93% after centrifugation at 4000r / min for 20min. Its performance meets the requirements of continuous inkjet printing technology, which specifies an ink viscosity of 2–5 cP and an average pigment particle size of less than 0.5 μm. The pigment paste does not clog the printhead during inkjet printing and exhibits no surface bleeding in cotton fabrics. When used with water-based inks for ballpoint pens, it writes for 400 meters without ink interruption. However, because ethylene glycol's moisturizing effect is relatively inferior to glycerol, prolonged storage may cause ink drying and difficulty in ink delivery in the printhead and pen tip.

[0038] Example 6

[0039] Take 20g of the modified pigment dispersion with hydrophilic sodium carboxylate groups prepared in Example 1, place it in a 100mL beaker, and add 0.025g of anionic dispersant sodium dodecyl sulfate and 0.5g of nonionic dispersant Tween-80 sequentially. Stir until homogeneous to obtain a pigment paste mixture. Subsequently, add 3.0g of glycerol and 0.16g of sodium benzoate to the above mixture, and stir to obtain an aqueous pigment pre-paste. Finally, transfer the above pigment pre-paste to a high-speed homogenizer, add 0.30g of TF-906 defoamer, and add deionized water until the total mass of the pigment paste reaches 50g. Homogenize it at 16500r / min for 20min to obtain the final aqueous pigment ink. The viscosity of the obtained pigment ink is measured to be 2.02cP, the particle size is 420nm, and the specific absorbance reaches 89% after centrifugation at 4000r / min for 20min. Its performance meets the requirements of continuous inkjet printing technology, which specifies an ink viscosity of 2–5 cP and an average pigment particle size of less than 0.5 μm. When used in inkjet printing, the ink paste causes no nozzle clogging and no seepage into cotton fabrics. When used with water-based inks for ballpoint pens, it writes for 350 meters without ink interruption.

[0040] Example 7

[0041] Take 10g of the modified pigment dispersion with hydrophilic sodium carboxylate groups prepared in Example 1, place it in a 50mL beaker, and add 0.050g of anionic dispersant sodium dodecyl sulfate and 0.75g of nonionic dispersant Tween-80 sequentially. Stir until homogeneous to obtain a pigment paste mixture. Subsequently, add 1.5g of propylene glycol and 0.08g of sodium benzoate to the above mixture, and stir to obtain an aqueous pigment pre-paste. Finally, transfer the above pigment pre-paste to a high-speed homogenizer, add 0.15g of TF-906 defoamer, and add deionized water until the total mass of the pigment paste reaches 25g. Homogenize it at 17000r / min for 20min to obtain the final aqueous pigment ink. The viscosity of the obtained pigment ink is measured to be 2.05cP, the particle size is 480nm, and the specific absorbance reaches 88% after centrifugation at 4000r / min for 20min. Its performance meets the requirements of continuous inkjet printing technology, which specifies an ink viscosity of 2–5 cP and an average pigment particle size of less than 0.5 μm. When used in inkjet printing, the ink paste causes no nozzle clogging and no seepage into cotton fabrics. When used with water-based inks for ballpoint pens, it writes for 330 meters without ink interruption.

[0042] Example 8

[0043] Take 30g of the modified pigment dispersion with hydrophilic sodium carboxylate groups prepared in Example 1, place it in a 100mL beaker, and add 0.075g of anionic dispersant sodium dodecyl sulfate and 1.2g of nonionic dispersant Tween-80 sequentially. Stir until homogeneous to obtain a pigment paste mixture. Subsequently, add 4.5g of glycerol and 0.24g of sodium benzoate to the above mixture, and stir to obtain an aqueous pigment pre-paste. Finally, transfer the above pigment pre-paste to a high-speed homogenizer, add 0.45g of TF-906 defoamer, and add deionized water until the total mass of the pigment paste reaches 60g. Homogenize it at 17000r / min for 20min to obtain the final aqueous pigment ink. The viscosity of the obtained pigment ink is measured to be 2.03cP, the particle size is 285nm, and the specific absorbance reaches 94% after centrifugation at 4000r / min for 20min. Its performance meets the requirements of continuous inkjet printing technology, which specifies an ink viscosity of 2–5 cP and an average pigment particle size of less than 0.5 μm. When used in inkjet printing, the ink paste causes no nozzle clogging and no seepage into cotton fabrics. When used with water-based inks for ballpoint pens, it writes for 400 meters without interruption of ink flow.

[0044] Comparative Example 1

[0045] 0.6g of Pigment Red 122 was placed in a 50mL beaker, followed by 0.025g of anionic dispersant sodium dodecyl sulfate, 0.5g of nonionic dispersant Tween-80, and 10mL of deionized water. The mixture was stirred until homogeneous to obtain a pigment paste mixture. Subsequently, 1.5g of glycerol and 0.08g of sodium benzoate were added to the mixture, and the mixture was stirred to obtain an aqueous pre-pigment paste. Finally, the pre-pigment paste was transferred to a high-speed homogenizer, and 0.15g of TF-906 defoamer was added, along with deionized water until the total mass of the paste reached 25g. The homogenizer was homogenized at 17000r / min for 20min to obtain the final aqueous pigment ink. The viscosity of the obtained pigment ink was measured to be 2.01cP, the particle size was 580nm, and some pigment particles were suspended above the ink. After centrifugation at 4000r / min for 20min, the specific absorbance reached 65%. Its performance does not meet the requirements for water-based ink applications.

[0046] Comparative Example 2

[0047] 10g of the modified pigment dispersion with hydrophilic sodium carboxylate groups prepared in Example 1 was placed in a 50mL beaker, and 0.035g of anionic dispersant sodium dodecyl sulfate was added. The mixture was stirred until homogeneous to obtain a pigment paste mixture. Subsequently, 1.5g of glycerol and 0.08g of sodium benzoate were added to the mixture, and the mixture was stirred to obtain an aqueous pigment pre-paste. Finally, the pigment pre-paste was transferred to a high-speed homogenizer, and 0.15g of TF-906 defoamer was added, along with deionized water until the total mass of the pigment paste reached 25g. The homogenizer was homogenized for 20min at 17000r / min to obtain the final aqueous pigment ink. The viscosity of the obtained pigment ink was measured to be 2.02cP, the particle size was 425nm, and the specific absorbance reached 78% after centrifugation at 4000r / min for 20min. Its performance meets the requirements of continuous inkjet printing technology, which specifies an ink viscosity of 2–5 cP and an average pigment particle size of less than 0.5 μm. When used in inkjet printing, the ink paste causes no nozzle clogging and no seepage into cotton fabrics. When used with water-based inks for ballpoint pens, it writes for 300 meters without ink interruption.

[0048] Comparative Example 3

[0049] 10g of the modified pigment dispersion with hydrophilic sodium carboxylate groups prepared in Example 1 was placed in a 50mL beaker, and 0.75g of nonionic dispersant Tween-80 was added. The mixture was stirred until homogeneous to obtain a pigment paste mixture. Subsequently, 1.5g of glycerol and 0.08g of sodium benzoate were added to the mixture, and the mixture was stirred to obtain an aqueous pigment pre-paste. Finally, the pigment pre-paste was transferred to a high-speed homogenizer, and 0.15g of TF-906 defoamer was added, along with deionized water until the total mass of the pigment paste reached 25g. The homogenizer was homogenized for 20min at 17000r / min to obtain the final aqueous pigment ink. The viscosity of the obtained pigment ink was measured to be 2.55cP, the particle size was 475nm, and the specific absorbance reached 80% after centrifugation at 4000r / min for 20min. Its performance meets the requirements of continuous inkjet printing technology, which specifies an ink viscosity of 2–5 cP and an average pigment particle size of less than 0.5 μm. When used in inkjet printing, the ink paste causes no nozzle clogging and no seepage into cotton fabrics. When used with water-based inks for ballpoint pens, it writes for 300 meters without ink interruption.

Claims

1. A water-based pigment red PR122 ink, characterized in that: The water-based Pigment Red PR122 ink has the following raw material composition by weight percentage: 30%–50% Pigment Red PR122 modified pigment dispersion system with hydrophilic sodium carboxyl groups, 0.05%–0.3% anionic dispersant, 1%–3% nonionic dispersant, 0.3%–0.8% defoamer, 0.02%–0.05% preservative and bactericide, 5%–10% glycerol, and 36%–63% deionized water; wherein, the Pigment Red PR122 modified pigment dispersion system with hydrophilic sodium carboxyl groups is obtained by first ionizing the surface of Pigment Red PR122 molecules, then adding chloroacetic acid, and grafting hydrophilic groups onto the pigment molecules for dispersion; The anionic dispersant is sodium dodecyl sulfate, and the nonionic dispersant is Tween-80; The preparation steps of the pigment red PR122 modified pigment dispersion system with hydrophilic sodium carboxyl groups are as follows: (1) N,N-dimethylformamide, Pigment Red 122 and potassium tert-butoxide were added sequentially to a flask and heated to 95-105 °C to react and ionize the pigment molecules on the surface. The color gradually changed from red to blackish-blue. When the blackish-blue color no longer deepened, chloroacetic acid was added and then the temperature was raised to 115-125 °C to react. The color of the system gradually returned to the color of Pigment Red PR122, and hydrophilic groups were grafted onto the pigment molecules. After washing with deionized water, the filter cake was obtained by suction filtration to remove impurities and residual solvent. (2) Add the pigment filter cake with the grafted hydrophilic group to deionized water, stir and disperse. After dispersion, add sodium hydroxide to adjust the pH value of the pigment paste to 9-10 to obtain the modified pigment red PR122 dispersion system with hydrophilic sodium carboxyl group.

2. The water-based pigment red PR122 ink according to claim 1, characterized in that: The defoamer is TF-906 type defoamer, and the preservative and bactericide is sodium benzoate.

3. A method for preparing water-based pigment red PR122 ink according to claim 1 or 2, characterized in that: The preparation method steps are as follows: S1. Anionic dispersant and nonionic dispersant are added sequentially to the pigment red PR122 modified pigment dispersion system containing hydrophilic sodium carboxyl groups, and the mixture is stirred to prepare a pigment mixture; S2. Add glycerol and preservatives / bactericides, stir and disperse to prepare pigment pre-color paste; S3. Add defoamer to the pigment pre-paste and add deionized water to adjust the proportion of each substance in the pigment paste. Then transfer it to a high-speed homogenizer for homogenization and dispersion to prepare water-based pigment ink.

4. The method for preparing water-based pigment red PR122 ink according to claim 3, characterized in that: The high-speed homogenizer operates at a speed of 15,000–18,000 r / min and a homogenization time of 15–25 min; the resulting water-based pigment ink has a particle size of less than 500 nm and a viscosity of 2–5 cP.

5. An application of the water-based pigment red PR122 ink according to claim 1 or 2, characterized in that: The water-based pigment red PR122 ink is used in ballpoint pen ink and textile inkjet printing.

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