Hydrophilic modified pigment, water-based ink as well as preparation method and application of hydrophilic modified pigment and water-based ink

Abstract

The invention relates to a hydrophilic modified pigment, water-based ink and a preparation method and application thereof, the hydrophilic modified pigment comprises phthalocyanine blue and sodium polyacrylate coating the outer layer of the phthalocyanine blue, and the phthalocyanine blue accounts for 45-75% by mass of the modified pigment. The water-based ink comprises the following components: 10-15 parts by weight of modified color paste, 25-30 parts by weight of a cosolvent, 1-3 parts by weight of water-based resin, 0.5-1 part by weight of a defoaming agent and water, and the amount of the water-based ink is 100 parts by weight. Wherein the modified color paste comprises the hydrophilic modified pigment, a wetting agent and water, and the hydrophilic modified pigment accounts for 7-10 wt% of the modified color paste. The hydrophilicity and dispersity of the modified pigment are improved, and the water-based ink prepared from the modified pigment is good in stability, clear in writing and good in application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation and application of organic pigments, mainly to the preparation and application fields of hydrophilic pigments, and particularly to a hydrophilically modified pigment, a water-based ink, and its preparation method and application. Background Art

[0002] Organic pigments have advantages such as bright colors and a complete color spectrum and are widely used in industries such as coatings, inks, and textile printing and dyeing. However, copper phthalocyanine pigment particles are extremely prone to flocculation or aggregation during the processes of preparation, storage, transportation, and processing. Moreover, organic pigments have low surface polarity and poor reactivity, are difficult to wet and disperse in the aqueous phase, and usually require the action of a large amount of dispersants to be evenly adhered to the surface of the target substance, which greatly affects the quality of the colored products and brings great inconvenience to industrial applications.

[0003] Pigment-based water-based ink is a kind of ink with water as the main dispersion medium, with a low content of organic solvents, reducing the pollution of the atmosphere caused by the emission of VOCs. The water-based ink with pigment as the colorant has good water resistance, light resistance, and oxidation resistance during writing. Pigments are insoluble in water and are evenly dispersed in the aqueous phase with the help of dispersants, while the pigment colorants are extremely prone to flocculation. Therefore, the anti-aging property of the pigment water-based ink is poor. During long-term storage, the deposition of components such as pigments will cause the imbalance of the ink system and affect the use performance of the ink.

[0004] To overcome the above difficulties, in the article "Study on the Hydrophilization Modification of C.I. Pigment Red 31 and Its Application Performance in Water-based Ink" published by Cao Ruichun et al., during the coupling process in pigment production, C.I. Pigment Red 31 was hydrophilically modified with naphthol AS-LC. Patent CN112852186A discloses a preparation method of a hydrophilically adjustable phthalocyanine blue pigment. The swollen phthalocyanine blue is dispersed in water, and then a hydrophobic modifier, a silicon source, and its hydrolysis agent are added. Finally, the addition of a cracking agent exposes the silicon hydroxyl groups in the encapsulated silicon source to improve hydrophilicity. Patent CN101033353A discloses a pigment-based water-based ink composition and its manufacturing method. The composition includes a pigment, a dispersant, a solvent, and water, and the dispersant is a hydrophilic flexible polymer binder to improve the water resistance of the ink. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a hydrophilically modified pigment, a water-based ink, and its preparation method. The technical problem to be solved is that the hydrophilicity and dispersion stability of the existing phthalocyanine blue pigment need to be improved, the stability of the phthalocyanine blue pigment water-based ink is poor, it is easy to deposit and cause ink imbalance, and a large amount of dispersants often need to be added during the hydrophilization modification process of the existing phthalocyanine blue pigment, which affects the quality of the colored products and limits the industrial application range of phthalocyanine blue.

[0006] To solve the above technical problems, the present invention uses phthalocyanine blue as a raw material, disperses it in anhydrous ethanol through mechanical stirring, adds acrylic acid monomer and initiator, and the generated sodium polyacrylate is insoluble in ethanol, thus coating the surface of the phthalocyanine blue pigment, making the pigment surface carry —COO — , through the modification of organic pigments, the prepared water-based ink has high stability, good coloring power and high gloss during writing.

[0007] Specifically, to achieve the above object, the present invention provides the following technical solutions:

[0008] A hydrophilically modified pigment, characterized in that it comprises phthalocyanine blue and sodium polyacrylate coated on the outer layer of phthalocyanine blue, and the mass fraction of phthalocyanine blue in the modified pigment is 45% to 75%, preferably 60% to 70%, more preferably 60% to 66%.

[0009] Preferably, in the above hydrophilically modified pigment, the particle size of the hydrophilically modified pigment is 200 - 350 nm, preferably 200 - 260 nm, more preferably 200 - 220 nm.

[0010] Preferably, the Zeta potential of the above hydrophilically modified pigment is -30 to -13 mV, preferably -30 mV.

[0011] Preferably, in the above hydrophilically modified pigment, the contact angle of water on the surface of the modified pigment is 50° to 70°, preferably 50° to 65°, more preferably 50° to 60°.

[0012] Preferably, in the above hydrophilically modified pigment, the modified pigment is prepared from raw materials comprising the following components: 2.5 - 10.5 parts by weight of acrylic acid; 0.05 - 0.4 parts by weight of water-soluble initiator; 0.1 g - 0.2 parts by weight of disodium ethylenediaminetetraacetate; 1.2 - 6.0 parts by weight of sodium hydroxide; 150 g - 180 parts by weight of anhydrous ethanol; 10 - 15 parts by weight of water; and 10 parts by weight of phthalocyanine blue.

[0013] The acrylic acid is preferably 4.0 - 7.5 parts by weight, more preferably 4.0 - 5.0 parts by weight; the water-soluble initiator is preferably 0.05 - 0.2 parts by weight.

[0014] The water-soluble initiator is persulfate, preferably potassium persulfate.

[0015] The molar ratio of acrylic acid to sodium hydroxide is 1:(1.0 - 1.2).

[0016] The present invention also provides a preparation method of the above hydrophilically modified pigment, comprising the following steps:

[0017] (1) Dissolve the initiator, disodium ethylenediaminetetraacetate, and sodium hydroxide in water, mix with absolute ethanol, and add acrylic acid to obtain a suspension;

[0018] (2) Add phthalocyanine blue to the suspension and disperse evenly;

[0019] (3) React under a nitrogen atmosphere to obtain a hydrophilically modified pigment.

[0020] Preferably, in the above preparation method, the reaction temperature in step (3) is 50 - 75 °C, preferably 60 - 75 °C, more preferably 63 - 65 °C.

[0021] Preferably, in the above preparation method, the reaction time is 4 - 8 h, preferably 4 - 6 h.

[0022] Preferably, in the above preparation method, the reaction process in step (3) is carried out under stirring, and the stirring speed is 600 - 1200 r / min, preferably 800 - 1000 r / min.

[0023] The present invention also provides an aqueous ink, which is characterized by comprising the following components:

[0024] 10 - 15 parts by weight of modified color paste, 25 - 30 parts by weight of co - solvent, 1 - 3 parts by weight of aqueous resin, 0.5 - 1 part by weight of defoamer, and water, with the total weight of the aqueous ink being 100 parts by weight;

[0025] The aqueous resin is preferably 1.0 - 1.5 parts by weight, more preferably 1.2 - 1.3 parts by weight.

[0026] Among them, the modified color paste includes the hydrophilically modified pigment described in claim 1, a wetting agent, and water. The hydrophilically modified pigment accounts for 7 - 10 wt% of the modified color paste, and the wetting agent accounts for 7 - 10 wt% of the modified color paste.

[0027] Preferably, the viscosity of the above aqueous ink is 4.5 - 25 mPa·s, preferably 5 - 10 mPa·s, more preferably 7 - 8 mPa·s.

[0028] Preferably, the pH value of the above aqueous ink is 7 - 8.

[0029] Preferably, the particle size of the above aqueous ink is 240 - 260 nm.

[0030] Preferably, in the above aqueous ink, the wetting agent is ethylene glycol.

[0031] Preferably, in the above aqueous ink, the co - solvent is selected from one or two of glycerol, ethanol, ethylene glycol, diethylene glycol, and isopropanol.

[0032] Preferably, in the above-mentioned aqueous ink, the cosolvent comprises 5-10 parts by weight of glycerol and 15-20 parts by weight of ethylene glycol.

[0033] Preferably, in the above-mentioned aqueous ink, the mass ratio of glycerol to ethylene glycol is (0.45-0.5):1.

[0034] Preferably, in the above-mentioned aqueous ink, the aqueous resin is selected from one or two of polyvinyl alcohol, polyvinylpyrrolidone, and acrylic emulsion.

[0035] Preferably, in the above-mentioned aqueous ink, the defoamer is a silicone defoamer.

[0036] The present invention also provides a preparation method of the above-mentioned aqueous ink, which is characterized by comprising the following steps:

[0037] (1) Mix the hydrophilically modified pigment, wetting agent and water described in claim 1 to obtain a modified color paste;

[0038] (2) Mix and stir water, cosolvent and aqueous resin evenly to obtain a mixed solution;

[0039] (3) Add the modified color paste to the mixed solution, and add the defoamer under stirring. After dispersing evenly, filter to obtain the aqueous ink.

[0040] Preferably, in the preparation method of the above-mentioned aqueous ink, in step (3), after adding the modified color paste to the mixed solution, under stirring, heat up to 60-70 °C, maintain for 0.5-1 h, stop heating, and continue stirring for 1.5-2.5 h.

[0041] Preferably, in the preparation method of the above-mentioned aqueous ink, heat up to 63-65 °C.

[0042] The present invention also provides the application of the above-mentioned hydrophilically modified pigment and the above-mentioned aqueous ink in the fields of coatings, inks, plastics, glass or textiles.

[0043] The advantages of the present invention are as follows: the preparation method is simple, the repeatability is high, and the phthalocyanine blue pigment modified by microencapsulation has better hydrophilicity, reduced particle size, improved dispersion stability, reduced particle aggregation, improved coloring effect, better compatibility with related products, and the modified pigment can reduce the use of related additives during application; the aqueous ink prepared from the pigment encapsulated by microcapsules reduces the usage amount of organic solvents, reduces the emission of VOCs, the ink preparation process does not require grinding and reduces the use of other dispersants, the process flow is simpler, and it can be applied in writing utensils such as fountain pens, aqueous gel pens, and marker pens, with smooth writing, clear handwriting, uniform and full line colors, high gloss, excellent water resistance and anti-aging properties. Brief Description of the Drawings

[0044] Figure 1 It is the transmission electron microscope image of the unmodified phthalocyanine blue pigment in Example 1.1, and the scale bar is 1 μm.

[0045] Figure 2 It is the transmission electron microscope image of the microcapsule-modified phthalocyanine blue pigment prepared in Example 1.1, and the scale bar is 500 nm.

[0046] Figure 3 It is the water contact angle image of the microcapsule-modified phthalocyanine blue pigment and the unmodified pigment prepared in Example 1.1.

[0047] Figure 4 It is the writing trace image of the water-based ink prepared in Example 2.1. Detailed implementation manners

[0048] In view of the current hydrophilicity and dispersibility of phthalocyanine blue pigments, the stability and anti-aging properties of phthalocyanine blue water-based inks need to be improved. The present invention provides a hydrophilized modified pigment and a water-based ink prepared therefrom, which are applied in writing instruments, with smooth writing and full color.

[0049] In a preferred implementation manner, the preparation method of the modified pigment and its water-based ink of the present invention includes: (1) Hydrophilization modification of phthalocyanine blue pigment: By precipitation polymerization, controlling time, temperature, monomer dosage, initiator dosage, and mechanical stirring speed, sodium polyacrylate is coated on the surface of the pigment, so that a large number of -COO- groups are wrapped on the outer layer of the pigment, making the surface of the pigment particles carry the same negative charge, increasing the electrostatic repulsion between particles, and improving the dispersion stability of the pigment; (2) Preparation of water-based ink: The water-based ink is composed of a modified pigment color paste, a solvent, deionized water, and an antifoaming agent. The average particle size of the modified pigment color paste can reach a minimum of 205 nm or less, which can replace the traditional production process of preparing ink by grinding and dispersing pigments. The ink prepared after the pigment is modified has improved coloring power and gloss, appropriate viscosity, excellent storage stability, and good writing feel, and is suitable for fountain pens, gel pens, and rollerball pens.

[0050] In a preferred implementation manner, the present invention provides a preparation method of a hydrophilized modified pigment, and the steps are as follows:

[0051] (1) Preparation of hydrophilized self-dispersing pigment modification:

[0052] S1: Take acrylic acid, an initiator, disodium ethylenediaminetetraacetate, and sodium hydroxide, dissolve them in ethanol, and add a small amount of deionized water;

[0053] S2: Add phthalocyanine blue pigment to the suspension in S1 during stirring;

[0054] S3: Introduce nitrogen into the reaction vessel and heat.

[0055] Further, in step S1, the initiator is a water-soluble initiator, commonly persulfate; disodium ethylenediaminetetraacetate is a metal chelating agent to protect the pigment particles from the erosion of metal ions during pigment production, storage, and use; adding a small amount of water can improve the solubility of the initiator and the chelating agent.

[0056] Further, in step S1, the amount of sodium hydroxide used is kept close to the molar mass of the acrylic monomer used.

[0057] Further, in step S2, after adding phthalocyanine blue, since the polyacrylate sodium generated by the reaction is insoluble in ethanol and gradually precipitates, it coats the surface of the phthalocyanine blue pigment, achieving the purpose of hydrophilic and self-dispersing the phthalocyanine blue pigment.

[0058] Further, by controlling factors such as the amount of acrylic monomer used, the amount of initiator used, time, temperature, stirring speed, etc., the hydrophilic and dispersing effects of the phthalocyanine blue pigment are better.

[0059] Further, the modification method of the present invention is the precipitation polymerization method, which is a pigment microencapsulation method. It can coat surfactants, modifiers, high molecular compounds, etc. on the surface of pigment particles, thereby changing the surface polarity of the particles, improving the binding force between the pigment particles and the medium, making it have better compatibility with the use medium, and improving properties such as wettability, dispersibility, specific surface area, coloring rate, and transparency, and improving the use fastness of the pigment particles.

[0060] In another preferred embodiment, the present invention provides a preparation application of a modified hydrophilic self-dispersing pigment in a water-based ink. The total weight of the water-based ink is 100 parts by weight, and its components are: 10 - 15 parts of modified color paste, 25 - 30 parts of cosolvent, 1 - 3 parts of resin, 0.5 - 1 part of defoamer, and the balance is deionized water.

[0061] In another preferred embodiment, the preparation steps of the water-based ink are as follows:

[0062] The first step, preparation of the color paste:

[0063] Take 5 g of modified pigment in a three-necked flask, add 50 ml of deionized water and 5 g of wetting agent ethylene glycol, stir at 600 r / min to disperse and wet the pigment, and obtain a modified color paste.

[0064] The second step: Preparation of the water-based ink

[0065] (1) Mix deionized water, cosolvent, and resin evenly by stirring;

[0066] (2) Add the color paste and stir mechanically at 600 r / min for 2 - 3 h, and add the defoamer in several portions during the stirring process;

[0067] (3) After the stirring is completed, let it stand still, and filter it under a filter paper with a pore size of 1um to obtain the finished product.

[0068] The cosolvent is one or two of glycerol, ethanol, ethylene glycol, diethylene glycol, and isopropanol.

[0069] The resin is one or two of water-based resins such as polyvinyl alcohol, polyvinylpyrrolidone, and acrylic emulsion.

[0070] Furthermore, to ensure the long-term use effect of the ink, appropriate amounts of additives such as rust inhibitors and fungicides can be added.

[0071] The following will further illustrate the hydrophilically modified pigment, water-based ink, and their preparation methods and applications according to the present invention through specific examples.

[0072] In the following examples, the information of the reagents and instruments used is shown in the following table. The phthalocyanine blue is phthalocyanine blue 15:3, and other reagents are all purchased from Sinopharm Chemical Reagent Co., Ltd.

[0073] Table 1 Information Table of Reagents and Instruments

[0074] Reagents / Instruments Specifications / Models Manufacturer / Source Silicone defoamer Polyurethane defoamer 599 Guangzhou Hanyiyuan New Materials Co., Ltd. Water contact angle tester DSA100 type Kruss Company of Germany Zeta-Nano Particle Sizer Nano-ZS90 British company MALVERN Rotational Viscometer NDJ-79 Shanghai Changji Geological Instrument Co., Ltd. Transmission electron microscopy HT-7700 Hitachi

[0075] Example 1 Preparation of Hydrophilic Modified Phthalocyanine Blue

[0076] Example 1.1

[0077] The preparation method of the hydrophilically modified pigment described in this example is as follows:

[0078] (1) Use a 250 ml three-necked flask as the reaction vessel, add 150 g of anhydrous ethanol to it. After dissolving 0.1 g of potassium persulfate initiator, 0.1 g of disodium ethylenediaminetetraacetate, and 2.8 g of sodium hydroxide in 10 ml of deionized water, mix it with anhydrous ethanol and add 5 ml of acrylic acid for dissolution;

[0079] (2) Add 10 g of phthalocyanine blue pigment to the reaction vessel, and disperse it by mechanical stirring at a stirring speed of 300 r / min;

[0080] (3) Place the reaction vessel in a water bath, introduce nitrogen into the reaction vessel, heat it up to 64 °C, adjust the mechanical stirring speed to 1000 r / min, and the reaction time is 6 h;

[0081] (4) After the reaction is completed, naturally cool the product to room temperature, filter and dry it to obtain the phthalocyanine blue modified pigment with a microcapsule structure.

[0082] Observe the morphologies of the phthalocyanine blue pigment before modification and the phthalocyanine blue modified pigment obtained in Example 1.1 by transmission electron microscopy, as shown in Figure 1 and Figure 2As shown, it can be seen from the figure that the phthalocyanine blue pigment before modification is flaky, and the phthalocyanine blue pigment after modification is spherical. The inner layer is phthalocyanine blue, and there is a polymer coating layer on the surface of phthalocyanine blue.

[0083] Weigh the mass of the modified pigment and calculate the mass fraction of the inner layer of phthalocyanine blue in the modified pigment. In the modified pigment obtained in this example, the mass fraction of the inner layer of phthalocyanine blue in the modified pigment is 61.7%.

[0084] The relevant parameters of the obtained modified pigment were tested by the following method: The modified pigment was pressed into tablets, and a water contact angle tester was used to measure the contact angle of water on the surface of the modified pigment powder, and a zeta-nano particle size analyzer was used to determine the average particle size and zeta potential of the pigment. The water contact angle diagrams of the modified pigment and the unmodified pigment obtained in Example 1.1 are as Figure 3 shown. It can be seen from the figure that the contact angle of the unmodified phthalocyanine blue pigment is 75.6°, and the contact angle of the modified pigment obtained in Example 1.1 is 54.1°.

[0085] The preparation methods of Examples 1.2 to 1.8 are similar to those of Example 1.1, except that the raw material addition amounts are different, as specifically shown in Table 2. The test results are shown in Table 3.

[0086] Weigh the mass of the modified pigment and calculate the mass fraction of the inner layer of phthalocyanine blue in the modified pigment: 71.8% for Example 1.2, 65.4% for Example 1.3, 53.9% for Example 1.4, 46.8% for Example 1.5, 60.1% for Example 1.6, 60.7% for Example 1.7, and 59.3% for Example 1.8.

[0087] Table 2 Raw material ratios in the examples

[0088]

[0089] Examples 1.9 to 1.12 are similar to Example 1.1, except that in step (3) of Example 1.9, the stirring speed is 600 r / min, in step (3) of Example 1.10, the stirring speed is 800 r / min, in step (3) of Example 1.11, the stirring speed is 900 r / min, and in step (3) of Example 1.12, the stirring speed is 1200 r / min.

[0090] Examples 1.13 and 1.14 are similar to Example 1.1, except that in step (3) of Example 1.13, the reaction temperature is 54 °C, and in step (3) of Example 1.14, the reaction temperature is 74 °C.

[0091] Table 3 Performance test results of the modified pigments obtained in the examples

[0092]

[0093] Examples 1.15 and 1.16 are similar to Example 1.1, except that in step (3) of Example 1.15, the reaction duration is 4 h, and in step (3) of Example 1.16, the reaction duration is 8 h.

[0094] The performance test results of the modified pigments obtained in Examples 1.9 to 1.16 are shown in Table 3.

[0095] As can be seen from the above table results, after microcapsule coating modification, the hydrophilicity and dispersibility of the pigments have been improved, making them more suitable for the preparation of water-based inks.

[0096] Preparation of Water-based Ink in Example 2

[0097] Example 2.1

[0098] Prepare a water-based ink with the modified pigment obtained in Example 1.1, and the method is as follows:

[0099] (1) Preparation of modified color paste: Take 5 g of modified pigment in a three-necked flask, add 50 ml of deionized water and 5 g of wetting agent ethylene glycol, and stir at 600 r / min to disperse and wet the pigment to obtain a modified color paste.

[0100] (2) Preparation of water-based ink: Place the three-necked flask in a water bath, take 56 g of deionized water in the three-necked flask, add 8 g of glycerol (or glycerin), 17 g of ethylene glycol, 3 g of polyvinyl alcohol, and 15 g of modified color paste under stirring, adjust the mechanical stirring speed to 600 r / min, heat to 64 °C, maintain for 30 minutes, stop heating, continue stirring for 2 h, and intermittently add 1 g of silicone defoamer during the stirring process; after the stirring is completed, let it stand and filter under a filter paper with a pore size of 1 μm to obtain a water-based ink.

[0101] Example 2.2

[0102] Prepare a water-based ink with the modified pigment obtained in Example 1.1, and the method is as follows:

[0103] (1) Preparation of modified color paste: Take 5 g of modified pigment in a three-necked flask, add 50 ml of deionized water and 5 g of wetting agent ethylene glycol, and disperse and wet the pigment at a stirring speed of 600 r / min to obtain a modified color paste.

[0104] (2) Preparation of water-based ink: Place a three-necked flask in a water bath. Take 57 g of deionized water in the three-necked flask, add 8 g of glycerol, 17 g of ethylene glycol, 2 g of polyvinyl alcohol, and 15 g of modified color paste while stirring. Adjust the mechanical stirring speed to 600 r / min, heat to 64 °C, maintain for 30 minutes, stop heating, and continue stirring for 2 h. Intermittently add 1 g of silicone defoamer during the stirring process. After the stirring ends, let it stand and filter under a filter paper with a pore size of 1 μm to obtain the water-based ink.

[0105] Example 2.3

[0106] Prepare water-based ink using the modified pigment obtained in Example 1.1, and the method is as follows:

[0107] (1) Preparation of modified color paste: Take 5 g of modified pigment in a three-necked flask, add 50 ml of deionized water and 5 g of wetting agent ethylene glycol, and disperse and wet the pigment at a stirring speed of 600 r / min to obtain the modified color paste.

[0108] (2) Preparation of water-based ink: Place a three-necked flask in a water bath. Take 57.5 g of deionized water in the three-necked flask, add 8 g of glycerol, 17 g of ethylene glycol, 1.5 g of polyvinyl alcohol, and 15 g of modified color paste while stirring. Adjust the mechanical stirring speed to 600 r / min, heat to 64 °C, maintain for 30 minutes, stop heating, and continue stirring for 2 h. Intermittently add 1 g of silicone defoamer during the stirring process. After the stirring ends, let it stand and filter under a filter paper with a pore size of 1 μm to obtain the water-based ink.

[0109] Example 2.4

[0110] Prepare water-based ink using the modified pigment obtained in Example 1.1, and the method is as follows:

[0111] (1) Preparation of modified color paste: Take 5 g of modified pigment in a three-necked flask, add 50 ml of deionized water and 5 g of wetting agent ethylene glycol, and disperse and wet the pigment at a stirring speed of 600 r / min to obtain the modified color paste.

[0112] (2) Preparation of water-based ink: Place a three-necked flask in a water bath. Take 57.8 g of deionized water in the three-necked flask, add 8 g of glycerol, 17 g of ethylene glycol, 1.2 g of polyvinyl alcohol, and 15 g of modified color paste while stirring. Adjust the mechanical stirring speed to 600 r / min, heat to 64 °C, maintain for 30 minutes, stop heating, and continue stirring for 2 h. Intermittently add 1 g of silicone defoamer during the stirring process. After the stirring ends, let it stand and filter under a filter paper with a pore size of 1 μm to obtain the water-based ink.

[0113] Example 2.5

[0114] Prepare water-based ink using the modified pigment obtained in Example 1.1, and the method is as follows:

[0115] (1) Preparation of modified color paste: Take 5 g of modified pigment in a three-necked flask, add 50 ml of deionized water and 5 g of wetting agent ethylene glycol, and disperse and wet the pigment at a stirring speed of 600 r / min to obtain the modified color paste.

[0116] (2) Preparation of water-based ink: Place the three-necked flask in a water bath, take 58 g of deionized water in the three-necked flask, add 8 g of glycerol, 17 g of ethylene glycol, 1 g of polyvinyl alcohol, and 15 g of modified color paste under stirring, adjust the mechanical stirring speed to 600 r / min, heat to 64 °C, maintain for 30 minutes, stop heating, continue stirring for 2 h, intermittently add 1 g of silicone defoamer during the stirring process; after the stirring is completed, let it stand and filter under a filter paper with a pore size of 1 μm to obtain the water-based ink.

[0117] Example 2.6

[0118] Prepare water-based ink using the modified pigment obtained in Example 1.10, and the method is as follows:

[0119] (1) Preparation of modified color paste: Take 5 g of modified pigment in a three-necked flask, add 50 ml of deionized water and 5 g of wetting agent ethylene glycol, and disperse and wet the pigment at a stirring speed of 600 r / min to obtain the modified color paste.

[0120] (2) Preparation of water-based ink: Place the three-necked flask in a water bath, take 59.8 g of deionized water in the three-necked flask, add 8 g of glycerol, 17 g of ethylene glycol, 1.2 g of polyvinyl alcohol, and 13 g of modified color paste under stirring, adjust the mechanical stirring speed to 600 r / min, heat to 64 °C, maintain for 30 minutes, stop heating, continue stirring for 2 h, intermittently add 1 g of silicone defoamer during the stirring process; after the stirring is completed, let it stand and filter under a filter paper with a pore size of 1 μm to obtain the water-based ink.

[0121] Example 2.7

[0122] Prepare water-based ink using the modified pigment obtained in Example 1.3, and the method is as follows:

[0123] (1) Preparation of modified color paste: Take 5 g of modified pigment in a three-necked flask, add 50 ml of deionized water and 5 g of wetting agent ethylene glycol, and disperse and wet the pigment at a stirring speed of 600 r / min to obtain the modified color paste.

[0124] (2) Preparation of water-based ink: Place a three-necked flask in a water bath, take 58.3 g of deionized water into the three-necked flask, add 10 g of propylene glycol, 20 g of ethylene glycol, 1.2 g of polyvinyl alcohol, and 10 g of modified color paste while stirring, adjust the mechanical stirring speed to 600 r / min, heat to 64°C, maintain for 30 minutes, stop heating, continue stirring for 2 hours, and intermittently add 0.5 g of silicone defoamer during the stirring process; after stirring, let it stand, and filter under 1 μm pore size filter paper to obtain water-based ink.

[0125] Comparative Example 1

[0126] (1) Preparation of unmodified color paste: 5 g of unmodified phthalocyanine blue pigment was placed in a three-necked flask, 50 ml of deionized water and 5 g of ethylene glycol (wetting agent) were added, and the pigment was dispersed and wetted at a stirring speed of 600 r / min to obtain a color paste.

[0127] (2) Take 58g of deionized water in a three-necked flask, add 8g of propylene glycol, 17g of ethylene glycol, 2g of polyvinyl alcohol, and 15g of unmodified color paste while stirring; adjust the mechanical stirring speed to 600r / min, heat to 64°C, maintain for 30 minutes, stop heating, continue stirring for 2h, and intermittently add 1g of silicone defoamer during the stirring process; after the stirring is completed, let it stand, and filter under a 1um pore size filter paper to obtain a water-based ink.

[0128] Basic ink performance test: (1) Use zeta-nanoparticle size analyzer to measure the particle size and zeta potential of pigment ink; (2) Use pH meter to test the pH value of ink; (3) Rotational viscometer to measure the viscosity of ink; (4) The stability of ink is measured by the state after centrifugation. The ink is centrifuged at 8500rpm for 10min and the centrifugation results are observed; (5) The writing effect of ink is measured by filling the ink with a 0.6mm fountain pen and writing, and the handwriting is observed. The test results are shown in the following table.

[0129] Table 4 Performance test results of water-based ink

[0130] Ink Evaluation Viscosity mPa·s pH Particle size (nm) Zeta potential (mV) stability Example 2.1 23.2 7.33 256.2 -12.4 There is supernatant and more precipitation Example 2.2 13.4 7.41 253.7 -11.9 No supernatant, more precipitation Example 2.3 9.6 7.28 245.6 -14.5 No supernatant, small amount of precipitation Example 2.4 7.0 7.58 244.9 -15.7 No supernatant, minimal precipitation Example 2.5 4.8 7.26 254.2 -14.3 No supernatant, small amount of precipitation Example 2.6 5.4 7.42 258.8 -14.5 No supernatant, small amount of precipitation Example 2.7 7.6 7.21 253.2 -15.2 No supernatant, minimal precipitation Comparative Example 1 16.0 7.66 391.2 -1.6 There is supernatant and a lot of precipitation

[0131] The aqueous ink obtained in Example 2.1 was used in a 0.6 mm fountain pen, and the writing effect was as follows: Figure 4 As shown in the figure, we can see that the writing feels good and the handwriting is clear.

[0132] It can be seen from the above table that the viscosity of water-based ink is affected by the color paste and water-soluble resin, and the color depth of the writing with water-based ink is affected by the amount of color paste used and the viscosity. The water-based ink prepared with modified pigments has good stability, clear writing, and good application prospects.

Claims

1. A hydrophilically modified pigment, characterized in that, It includes phthalocyanine blue and sodium polyacrylate coated on the outer layer of phthalocyanine blue, and the mass fraction of phthalocyanine blue in the modified pigment is 45% - 75%.

2. The hydrophilized modified pigment according to claim 1, wherein, The particle size of the hydrophilically modified pigment is 200 - 350 nm.

3. The hydrophilically modified pigment according to claim 1, wherein, The modified pigment is prepared from raw materials comprising the following components: 2.5 - 10.5 parts by weight of acrylic acid; 0.05 - 0.4 parts by weight of water-soluble initiator; 0.1 g - 0.2 parts by weight of disodium ethylenediaminetetraacetate; 1.2 - 6.0 parts by weight of sodium hydroxide; 150 g - 180 parts by weight of absolute ethanol; 10 - 15 parts by weight of water; and 10 parts by weight of phthalocyanine blue.

4. The preparation method of the hydrophilically modified pigment according to claim 1, comprising the following steps: (1) Dissolve the initiator, disodium ethylenediaminetetraacetate and sodium hydroxide in water, mix with absolute ethanol, and add acrylic acid to obtain a suspension; (2) Add phthalocyanine blue to the suspension and disperse evenly; (3) React under a nitrogen atmosphere to obtain the hydrophilically modified pigment.

5. According to the preparation method described in claim 4, wherein, The reaction temperature in step (3) is 50 - 75 °C.

6. An aqueous ink, characterized in that, It includes the following components: 10 - 15 parts by weight of modified color paste, 25 - 30 parts by weight of cosolvent, 1 - 3 parts by weight of water-based resin, 0.5 - 1 part by weight of defoamer and water, and the water-based ink is 100 parts by weight; Among them, the modified color paste includes the hydrophilically modified pigment according to claim 1, wetting agent and water, and the hydrophilically modified pigment accounts for 7 - 10 wt% of the modified color paste.

7. The aqueous ink according to claim 6, wherein, The viscosity of the water-based ink is 4.5 - 25 mPa·s.

8. The preparation method of the aqueous ink according to claim 6, characterized in that, It includes the following steps: (1) Mix the hydrophilically modified pigment according to claim 1, wetting agent and water to obtain a modified color paste; (2) Mix water, cosolvent and water-based resin evenly by stirring to obtain a mixed solution; (3) Add the modified color paste to the mixed solution, add the defoamer under stirring, disperse evenly, and then filter to obtain the water-based ink.

9. The preparation method of the aqueous ink according to claim 8, wherein, In step (3), after adding the modified color paste to the mixed solution, under stirring, heat up to 60 - 70 °C, maintain for 0.5 - 1 h, stop heating, and continue stirring for 1.5 - 2.5 h.

10. The application of the hydrophilically modified pigment according to claim 1 and the water-based ink according to claim 7 in the fields of coatings, inks, plastics, glass or textiles.

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