Anionic hyperdispersant, modified phthalocyanine blue and preparation method and application thereof

Abstract

The invention relates to an anionic hyperdispersant, modified phthalocyanine blue and a preparation method and application thereof, the hyperdispersant is formed by copolymerization of styrene, a polymerizable monomer and a cross-linking agent, and the polymerizable monomer is selected from sodium vinyl phosphate, sodium acrylate, sodium vinyl benzoate or sodium p-styrenesulfonate; the cross-linking agent is selected from N, N-methylene bisacrylamide or divinyl benzene; preferably, the hyperdispersant is formed by copolymerization of styrene, sodium acrylate and N, N-methylene bisacrylamide. The modified phthalocyanine blue comprises phthalocyanine blue and an anionic hyperdispersant coating the surface of the phthalocyanine blue, the obtained hyperdispersant can improve the dispersibility of the phthalocyanine blue pigment, and the obtained modified phthalocyanine blue is high in coloring degree and high in stability in water and has higher application value.

Description

Technical Field

[0001] This invention relates to the field of preparation of anionic dispersants, and more particularly to the field of preparation of anionic dispersants for organic pigments, specifically to an anionic superdispersant, modified phthalocyanine blue, its preparation method and application. Background Technology

[0002] Some ultrafine powders, such as pigments, have small particle sizes, large specific surface areas, and high specific surface energies. Due to the hydrogen bonds and van der Waals forces between these particles, they attract each other and agglomerate into larger particles. In practical applications, this leads to difficulties in dispersion and sedimentation. Therefore, dispersants are needed to disperse pigments during application. Dispersants are not only suitable for dispersing fillers but also for dispersing various solid particles such as carbon black, titanium dioxide, and metal powders. They are widely used in industries such as coatings, inks, plastics, rubber, cosmetics, and pharmaceuticals.

[0003] Traditional dispersants include polyurethane (PU), polyacrylic acid (PAA), polyvinyl alcohol (PVA) and their derivatives, as well as polyelectrolytes. These dispersants are mainly adsorbed onto pigments through classical hydrogen bonding or electrostatic interactions, making it difficult to maintain stability over long periods. They also suffer from drawbacks such as requiring large amounts and being prone to foaming. Furthermore, these dispersants with single functional groups have limited ability to complex and stabilize metal ions on the surface of many solid particles.

[0004] Superdispersants are polymeric dispersants with a unique molecular structure containing both hydrophilic and hydrophobic groups. The anchoring groups on the molecular structure can tightly adsorb onto the surface of ultrafine powders, preventing desorption, while the solvated chains exhibit good compatibility with the dispersion medium, adopting a relatively extended conformation in the dispersion medium to form a sufficiently thick protective layer on the surface of solid particles. Currently, although many polymeric dispersants have been developed, most of these dispersants have complex synthesis processes, relatively weak interactions with pigments, and limited applicability to a wide range of pigments. Therefore, there is a need to develop dispersants that form stronger interactions with pigments. Summary of the Invention

[0005] The technical problem solved by this invention is that the interaction between existing polymer dispersants for pigments and pigment particles is relatively weak, and the dispersion stability, gloss and coloring strength of pigments in water need to be improved.

[0006] To address the aforementioned technical problems, this invention provides a polymer-type superdispersant. The dispersant is used to encapsulate raw phthalocyanine blue using microencapsulation technology to obtain modified phthalocyanine blue pigment. The superdispersant exhibits heat resistance and high dispersibility. The encapsulated pigment has a fuller morphology, improving pigment aggregation. Furthermore, the pigment particle size is reduced from 363.2 nm to approximately 180 nm-230 nm, and the zeta potential increases from -3.1 mV to -41.1 mV, enhancing the pigment's dispersion stability in water. The pigment's gloss and tinting strength are also further improved.

[0007] Specifically, in view of the shortcomings of the existing technology, the present invention provides the following technical solution:

[0008] An anionic superdispersant, characterized in that it is copolymerized from styrene, a polymerizable monomer, and a crosslinking agent, wherein the polymerizable monomer is selected from sodium vinyl phosphate, sodium acrylate, sodium vinyl benzoate, or sodium styrene sulfonate; and the crosslinking agent is selected from N,N-methylenebisacrylamide or divinylbenzene.

[0009] Preferably, in the above-mentioned anionic superdispersant, the polymerizable monomer is sodium acrylate, the crosslinking agent is N,N-methylenebisacrylamide, and the structural formula of the superdispersant is:

[0010]

[0011] Where 2≤x≤5, 10≤y≤50, and 10≤z≤50.

[0012] Preferably, in the above-mentioned anionic superdispersant, the superdispersant is prepared from the following raw materials:

[0013] Acrylic acid 2.4-2.6 parts by weight, sodium hydroxide 1.2-1.5 parts by weight, potassium persulfate 0.1-0.2 parts by weight, N,N-methylenebisacrylamide 0.2-0.3 parts by weight, and styrene 1-5 parts by weight.

[0014] Preferably, the styrene content is 2.0 to 2.5 parts by weight.

[0015] The present invention also provides a method for preparing the above-mentioned anionic superdispersant, characterized by comprising the following steps:

[0016] (1) Disperse acrylic acid, sodium hydroxide, sodium persulfate and N,N-methylenebisacrylamide in a solvent to obtain an aqueous phase;

[0017] (2) Add styrene to the aqueous phase and ultrasonically emulsify to obtain an oil-in-water emulsion;

[0018] (3) The oil-in-water emulsion is polymerized under nitrogen bubbling conditions to obtain the anionic superdispersant.

[0019] Preferably, in the above-mentioned method for preparing the superdispersant, the solvent in step (1) is a mixed solution of anhydrous ethanol and water, and the volume ratio of anhydrous ethanol to water is 2:(3~5).

[0020] Preferably, in the above-mentioned method for preparing the superdispersant, in step (3), the polymerization reaction temperature is 70~75℃, the reaction time is 8~10h, and the stirring speed is 500~600rpm.

[0021] The present invention also provides a modified phthalocyanine blue, characterized in that it comprises phthalocyanine blue and the above-mentioned anionic superdispersant coated on the surface of phthalocyanine blue.

[0022] This invention also provides a method for preparing the above-mentioned modified phthalocyanine blue, characterized by comprising the following steps:

[0023] (1) Disperse acrylic acid, sodium hydroxide, sodium persulfate and N,N-methylenebisacrylamide in a solvent to obtain an aqueous phase;

[0024] (2) Add styrene and phthalocyanine blue raw materials to the aqueous phase and emulsify by ultrasonication to obtain phthalocyanine blue pre-dispersion;

[0025] (3) The phthalocyanine blue pre-dispersion was prepolymerized at 40~50℃ under nitrogen bubbling conditions, and then polymerized at 60~80℃ to obtain the modified phthalocyanine blue.

[0026] Preferably, in the above-mentioned method for preparing modified phthalocyanine blue, the mass ratio of the phthalocyanine blue raw material to the acrylic acid is (1.5~2.5):1. More preferably, it is 2:1.

[0027] Preferably, in the above-mentioned method for preparing modified phthalocyanine blue, the dispersion process in step (1) is carried out under stirring conditions, and the stirring speed is 400~500 rpm.

[0028] Preferably, in the above-mentioned method for preparing modified phthalocyanine blue, the ultrasonic emulsification time in step (2) is 5~10 min.

[0029] Preferably, in the above-mentioned method for preparing modified phthalocyanine blue, in step (3), the stirring speed of the prepolymerization is 700~800 rpm and the time is 30~35 min, and the stirring speed of the polymerization reaction is 700~800 rpm and the time is 4~5 h.

[0030] Preferably, in the modified phthalocyanine blue described above, the contact angle of water on the surface of the modified phthalocyanine blue is 50~75°, more preferably 60~65°.

[0031] Preferably, the particle size of the modified phthalocyanine blue pigment is 150~250nm, and more preferably 180~210nm.

[0032] The present invention also provides the application of the above-mentioned anionic superdispersant, or the above-mentioned modified phthalocyanine blue, in the fields of coatings, inks, plastics, rubber, cosmetics, or pharmaceuticals.

[0033] The advantages of this invention are: (1) The modified phthalocyanine blue obtained by this invention has good dispersion effect and exhibits low viscosity when used at high concentrations. (2) The modified phthalocyanine blue pigment obtained by this invention has excellent high temperature resistance. (3) The anionic superdispersant used in this invention interacts with the Cu on the phthalocyanine blue through π-π bond interactions, electrostatic interactions, and... 2+ Complexation occurs, and these interactions weaken the hydrogen bonds between pigment molecules, thus strengthening the interaction between the superdispersant and the pigment. Microencapsulation technology further ensures that the superdispersant is uniformly coated on the surface of phthalocyanine blue, thereby achieving long-term dispersion stability of phthalocyanine blue in aqueous systems. Attached Figure Description

[0034] Figure 1 The structure of the superdispersant obtained in Example 1 is shown below.

[0035] Figure 2 The infrared spectra are those of the superdispersant obtained in Example 1, the original phthalocyanine blue, and the modified phthalocyanine blue obtained in Example 2.4.

[0036] Figure 3 In the images, A and B are scanning electron microscope (SEM) images of the original phthalocyanine blue; C and D are SEM images of the modified phthalocyanine blue obtained from Example 2.4.

[0037] Figure 4 The image shows the zeta potential distribution of the modified phthalocyanine blue obtained in Example 2.4.

[0038] Figure 5 The images show the UV-Vis absorption spectra of the original phthalocyanine blue and the modified phthalocyanine blue obtained in the examples.

[0039] Figure 6 In the images, A1, B1, and C1 are photographs of the modified phthalocyanine blue obtained in Example 2.4, the phthalocyanine blue modified with sodium polyacrylate (commercially available modified phthalocyanine blue) modified with conventional dispersant, and the original phthalocyanine blue dispersed in water, respectively. A2, B2, and C2 are photographs of the modified phthalocyanine blue obtained in Example 2.4, the phthalocyanine blue modified with sodium polyacrylate (commercially available modified phthalocyanine blue) modified with conventional dispersant, and the original phthalocyanine blue dispersed in water and left to stand for two months, respectively.

[0040] Figure 7 The results are the heat stability test results of the modified phthalocyanine blue and the original phthalocyanine blue obtained in Example 2.4. Detailed Implementation

[0041] Given that the dispersibility, heat resistance and stability of phthalocyanine blue pigment still need to be improved, this invention prepares an anionic superdispersant and phthalocyanine blue pigment modified by the superdispersant.

[0042] In a preferred embodiment, the present invention provides an anionic-π type superdispersant for dispersing the organic pigment phthalocyanine blue. The anionic-π type dispersant is prepared by copolymerizing a polymerizable carboxylate or sulfonate with a benzene ring-containing monomer using a chemical method. During the preparation of the superdispersant, phthalocyanine blue is added, allowing the superdispersant to uniformly coat the surface of the phthalocyanine blue, further enhancing the interaction between the superdispersant and phthalocyanine blue.

[0043] Furthermore, the polymerizable salt mentioned above is one of sodium vinyl phosphate, sodium acrylate, sodium vinyl benzoate, or sodium styrene sulfonate.

[0044] Furthermore, the aforementioned benzene ring monomer was selected as styrene.

[0045] The preparation steps of the superdispersant are as follows: Deionized water was added to a 250 ml three-necked flask as the dispersion medium, followed by potassium persulfate initiator at a mass fraction of 2% of the comonomer, acrylic acid and sodium hydroxide of the same molar mass, and stirred to obtain an aqueous phase. After reacting for 10 min, styrene was added, and ultrasonic emulsification was performed for 5 min. The N2 device was connected, and bubbling was performed to make the reaction system have an inert atmosphere. The temperature was heated to 70℃, and the solution turned milky white. This was maintained for 10 h. After the reaction was completed, the solution was collected by centrifugation, washed with anhydrous ethanol and deionized water, and vacuum dried to obtain anionic superdispersant.

[0046] In another preferred embodiment, the present invention provides a process for preparing phthalocyanine blue coated and modified by the above-mentioned superdispersant: First, acrylic acid, sodium hydroxide, potassium persulfate, and a crosslinking agent are dissolved in deionized water and anhydrous ethanol at room temperature and stirred to obtain an aqueous phase. Then, styrene (St) and phthalocyanine blue are mixed at room temperature to obtain an oil phase. The oil phase is then directly poured into the aqueous phase and ultrasonically emulsified for 10 min. The resulting oil-in-water emulsion is transferred to a three-necked flask and immersed in a water bath at 70°C under a nitrogen atmosphere, stirred at 800 rpm for 5 h. Finally, the coated and modified phthalocyanine blue is collected by centrifugation, washed three times with ethanol, then washed three times with deionized water, and vacuum dried.

[0047] Furthermore, the above-mentioned N2 bubbling time is 30-60 min.

[0048] Furthermore, the crosslinking agent mentioned above can be one of N,N-methylenebisacrylamide and divinylbenzene, preferably N,N-methylenebisacrylamide.

[0049] Furthermore, by changing the proportion of comonomers, phthalocyanine blue can be adapted for use in different polar environments.

[0050] The preferred ratio of anhydrous ethanol to deionized water in the aqueous phase is 2:3.

[0051] Preferably, the mass ratio of styrene, acrylic acid and phthalocyanine blue is (2.0~2.5):(2.4~2.6):(4~6), more preferably 1:1:2.

[0052] The following specific examples further illustrate the superdispersant, modified phthalocyanine blue, their preparation methods, and applications described in this invention.

[0053] In the examples below, the information on the reagents and instruments used is shown in the table below. All other reagents were purchased from Sinopharm Group.

[0054] Table 1. Reagent and Instrument Information Sheet

[0055] Reagents / Instruments Specifications / Model Manufacturer / Source Phthalocyanine Blue PB15∶3 Anhui Shenlanhua Pigment Co., Ltd. Commercially available modified phthalocyanine blue k-334 Zhonglian Fine Chemical Co., Ltd. Fourier transform infrared spectrometer Cary 630 FTIR Agilent Scanning electron microscope SU8020 Zeiss Germany Zeta potential and nanoparticle size analyzer Nano-ZS90 model MALVERN, UK UV-Vis spectrophotometer UV-26600i Shimadzu Contact angle measuring instrument DSA-100 Kruss GmbH (Germany)

[0056] Example 1 Preparation of Hyperdispersant

[0057] (1) 5 g acrylic acid, 2.8 g sodium hydroxide, 0.2 g potassium persulfate and 0.5 g N,N-methylenebisacrylamide (MBA) were dispersed and dissolved in a mixed solvent of 40 ml anhydrous ethanol and 60 ml deionized water at room temperature and under stirring at 400 rpm to obtain an aqueous phase.

[0058] (2) Add 10 g of styrene to the aqueous phase and ultrasonically emulsify for 5 min to obtain an oil-in-water emulsion.

[0059] (3) The oil-in-water emulsion was transferred to a three-necked flask and immersed in a water bath at 70°C under nitrogen bubbling, and stirred at 500 rpm for 10 h. The synthesized emulsion was collected by centrifugation, washed three times with ethanol, then washed three times with deionized water, and dried under vacuum to obtain the superdispersant, named P(St-SA-MBA).

[0060] The structural formula of the superdispersant is as follows: Figure 1 As shown, the superdispersant is copolymerized from styrene, sodium polyacrylate and MBA, wherein 2≤x≤5, 10≤y≤50, and 10≤z≤50.

[0061] Example 2 Preparation of Modified Phthalocyanine Blue

[0062] Example 2.1

[0063] (1) 2.5 g acrylic acid, 1.4 g sodium hydroxide, 0.15 g potassium persulfate and 0.25 g N,N-methylenebisacrylamide (MBA) were dispersed and dissolved in a mixed solution of 20 ml anhydrous ethanol and 50 ml deionized water at room temperature and under stirring at 400 rpm to obtain an aqueous phase.

[0064] (2) Add 1 g of styrene and 5 g of phthalocyanine blue powder to the aqueous phase and ultrasonically emulsify for 10 min to obtain phthalocyanine blue pre-dispersion.

[0065] (3) The phthalocyanine blue pre-dispersion was transferred into a three-necked flask, and nitrogen gas was bubbled through it. The mixture was stirred at 500 rpm and heated to 50 °C for prepolymerization. After maintaining this temperature for 30 min, the stirring speed was increased to 800 rpm, and the mixture was heated to 70 °C. The mixture was then immersed in a 70 °C water bath and stirred for 4 h to obtain modified phthalocyanine blue. The modified phthalocyanine blue was collected by centrifugation, washed three times each with ethanol and deionized water, and then vacuum dried to obtain the modified phthalocyanine blue pigment coated with the dispersant.

[0066] Example 2.2

[0067] (1) 2.5 g acrylic acid, 1.4 g sodium hydroxide, 0.1 g potassium persulfate and 0.25 g N,N-methylenebisacrylamide (MBA) were dispersed and dissolved in a mixed solution of 20 ml anhydrous ethanol and 40 ml deionized water at room temperature and under stirring at 400 rpm to obtain an aqueous phase.

[0068] (2) Add 1.5 g of styrene and 5 g of phthalocyanine blue powder to the aqueous phase and ultrasonically emulsify for 8 min to obtain phthalocyanine blue pre-dispersion.

[0069] (3) The phthalocyanine blue pre-dispersion was transferred into a three-necked flask, and nitrogen gas was bubbled through it. The mixture was stirred at 500 rpm and heated to 45°C for prepolymerization. After maintaining this temperature for 30 min, the stirring speed was increased to 800 rpm, and the mixture was heated to 80°C. The mixture was then immersed in an 80°C water bath and stirred for 5 h to obtain modified phthalocyanine blue. The modified phthalocyanine blue was collected by centrifugation, washed three times each with ethanol and deionized water, and then vacuum dried to obtain the modified phthalocyanine blue pigment coated with the dispersant.

[0070] Example 2.3

[0071] (1) 2.5 g acrylic acid, 1.4 g sodium hydroxide, 0.1 g potassium persulfate and 0.25 g N,N-methylenebisacrylamide (MBA) were dispersed and dissolved in a mixed solution of 20 ml anhydrous ethanol and 30 ml deionized water at room temperature and under stirring at 400 rpm to obtain an aqueous phase.

[0072] (2) Add 2 g of styrene and 5 g of phthalocyanine blue powder to the aqueous phase and ultrasonically emulsify for 10 min to obtain phthalocyanine blue pre-dispersion.

[0073] (3) The phthalocyanine blue pre-dispersion was transferred into a three-necked flask, and nitrogen gas was bubbled through it. The mixture was stirred at 500 rpm and heated to 45°C for prepolymerization. After maintaining this temperature for 30 min, the stirring speed was increased to 800 rpm, and the mixture was heated to 70°C. The mixture was then immersed in a 70°C water bath and stirred for 5 h to obtain modified phthalocyanine blue. The modified phthalocyanine blue was collected by centrifugation, washed three times each with ethanol and deionized water, and then vacuum dried to obtain the modified phthalocyanine blue pigment coated with the dispersant.

[0074] Example 2.4

[0075] (1) 2.5 g acrylic acid, 1.4 g sodium hydroxide, 0.1 g potassium persulfate and 0.25 g N,N-methylenebisacrylamide (MBA) were dispersed and dissolved in a mixed solution of 20 ml anhydrous ethanol and 30 ml deionized water at room temperature and under stirring at 400 rpm to obtain an aqueous phase.

[0076] (2) Add 2.5 g of styrene and 5 g of phthalocyanine blue powder to the aqueous phase and ultrasonically emulsify for 10 min to obtain phthalocyanine blue pre-dispersion.

[0077] (3) The phthalocyanine blue pre-dispersion was transferred into a three-necked flask, and nitrogen gas was bubbled through it. The mixture was stirred at 500 rpm and heated to 45°C for prepolymerization. After maintaining this temperature for 30 min, the stirring speed was increased to 800 rpm, and the mixture was heated to 70°C. The mixture was then immersed in a 70°C water bath and stirred for 5 h to obtain modified phthalocyanine blue. The modified phthalocyanine blue was collected by centrifugation, washed three times each with ethanol and deionized water, and then vacuum dried to obtain the modified phthalocyanine blue pigment coated with the dispersant.

[0078] Example 2.5

[0079] (1) 2.5 g acrylic acid, 1.4 g sodium hydroxide, 0.1 g potassium persulfate and 0.25 g N,N-methylenebisacrylamide (MBA) were dispersed and dissolved in a mixed solution of 20 ml anhydrous ethanol and 30 ml deionized water at room temperature and under stirring at 400 rpm to obtain an aqueous phase.

[0080] (2) Add 5 g of styrene and 5 g of phthalocyanine blue powder to the aqueous phase and ultrasonically emulsify for 10 min to obtain phthalocyanine blue pre-dispersion.

[0081] (3) The phthalocyanine blue pre-dispersion was transferred into a three-necked flask, and nitrogen gas was bubbled through it. The mixture was stirred at 500 rpm and heated to 45°C for prepolymerization. After maintaining this temperature for 30 min, the stirring speed was increased to 800 rpm, and the mixture was heated to 70°C. The mixture was then immersed in a 70°C water bath and stirred for 5 h to obtain modified phthalocyanine blue. The modified phthalocyanine blue was collected by centrifugation, washed three times each with ethanol and deionized water, and then vacuum dried to obtain the modified phthalocyanine blue pigment coated with the dispersant.

[0082] The samples obtained in the examples were characterized as follows:

[0083] (1) The infrared spectra of the superdispersant P(St-SA-MBA) obtained in Example 1, the original phthalocyanine blue PB, and the modified phthalocyanine blue PB@P(St-SA-MBA) obtained in Example 2.4 were detected by Fourier transform infrared spectroscopy. The results are as follows: Figure 2 As shown.

[0084] Depend on Figure 2 It is evident that the superdispersant was successfully coated onto phthalocyanine blue. At 3486 cm⁻¹ -1 The broad absorption peak at 2925 cm⁻¹ is due to the stretching vibration of the OH bond in the carboxyl group. -1 2854 cm -1 These are stretching vibration peaks in -CH and -CH2, respectively; 1730 cm⁻¹ -1 It is the carbonyl stretching vibration peak in the ester group; 1640 cm⁻¹ -1 It is the absorption peak of the carbonyl stretching vibration in amides; 1596 cm⁻¹ -1 It is the bending vibration peak of NH on the amide; 1558 cm⁻¹ -1 and 1450 cm -1 It is the stretching vibration peak of COO-; 3074 cm⁻¹ -1 3031 cm -1 The absorption peak is due to the stretching vibration of the CH group in the benzene ring. This indicates that the superdispersant contains abundant -Ph, OH, NH, COOH, COO-, and CONH groups. The anions in the superdispersant chain form electrostatic interactions or salt-bridged hydrogen bonds with the pigment, while the benzene ring forms π-π interactions with the pigment. Atoms containing lone pairs of electrons interact with electron-deficient metal ions to form stable, cyclic, multidentate coordination complexes. These interactions work synergistically to promote the dissociation of the intermolecular π-π stacked backbone or the classical hydrogen bond network of the pigment.

[0085] (2) The microstructure of the original phthalocyanine blue and the modified phthalocyanine blue was detected by scanning electron microscopy. Figure 3In Figures A and B, we see scanning electron microscope (SEM) images of the original phthalocyanine blue; in Figures C and D, we see SEM images of the modified phthalocyanine blue obtained by coating the original phthalocyanine blue with the superdispersant prepared in Example 2.4. As shown in the figures, the unmodified phthalocyanine blue particles are "rice grain-like," difficult to disperse, and tend to clump together. The modified phthalocyanine blue particles are microspheres, exhibiting better dispersion.

[0086] (3) The potential distribution of the modified phthalocyanine blue obtained in Example 2.4 was detected using a Zeta potentiometer, such as... Figure 4 As shown in Table 2, the detection results of particle size and zeta potential are shown in Table 2.

[0087] (4) The contact angle detection method is as follows: the phthalocyanine blue powder is pressed into a sheet at 10 MPa, and the contact angle of water on the surface of the modified pigment powder is determined using a DSA100 droplet shape analyzer.

[0088] Table 2. Detection results of particle size, zeta potential, and contact angle of phthalocyanine blue pigment.

[0089] raw material Particle size / nm Zeta potential / mV Contact angle / ° Pre-modified Phthalocyanine Blue Pigment 363.2 -3.1 81.2 Example 2.1 184.0 -33.7 55.9 Example 2.2 186.4 -35.5 57.3 Example 2.3 189.2 -38.8 60.7 Example 2.4 200.8 -41.1 62.4 Example 2.5 230.9 -41.1 70.2

[0090] As shown in Table 2, compared with the original phthalocyanine blue before modification, the particle size of the modified phthalocyanine blue obtained in the embodiments of the present invention is significantly reduced. In the embodiments, as the amount of styrene increases, the pigment particle size increases, and the zeta potential also increases. When the mass ratio of phthalocyanine blue to acrylic acid is 1:1 and 2:1, the particle size and zeta potential hardly change, reaching an equilibrium state. The addition of the comonomer styrene allows for better adsorption of the pigment through π-π interactions. The longer individual polymer chains allow for more effective "spreading" of a fixed number of negatively charged groups on the particle surface and in the surrounding space, increasing the surface charge density. The stronger hydrophobicity may improve the integrity and firmness of the coating, reducing the number of charge neutralization points.

[0091] (5) Coloring strength test of modified phthalocyanine blue

[0092] Figure 5 The figures show the UV-Vis absorption spectra of the modified phthalocyanine blue and the original phthalocyanine blue obtained in the examples. As can be seen from the figures, the modified phthalocyanine blue obtained in Examples 2.1 to 2.5 has two obvious absorption peaks at 625 nm and 720 nm, which are the Q band of phthalocyanine blue. Under the action of the superdispersant, a blue shift occurs, and the UV-Vis absorption value of the modified phthalocyanine blue is significantly improved. Under the same dispersion conditions, this indicates that the color intensity of phthalocyanine blue is improved by modification with a superdispersant.

[0093] (6) Dispersibility test of modified phthalocyanine blue in pure water

[0094] To test and verify the effectiveness of the present invention, phthalocyanine blue was selected as the raw material. The modified phthalocyanine blue in Example 2.4 and the traditional dispersant sodium polyacrylate modified phthalocyanine blue (commercially available modified phthalocyanine blue) were used as the sample for comparison. The dispersion stability of the modified phthalocyanine blue in pure water was tested.

[0095] Take 20 mg of sample into a sample bottle, add 20 ml of deionized water, and sonicate for 5 min to obtain a uniformly distributed blue suspension. Let it stand naturally at room temperature for two months and observe its dispersion state.

[0096] Figure 6 In the figures, A1, B1, and C1 are photographs of the modified phthalocyanine blue obtained in Example 2.4, the phthalocyanine blue modified with the traditional dispersant sodium polyacrylate, and the original phthalocyanine blue dispersed in water, respectively, representing blue suspensions. A2, B2, and C2 show their dispersion states after two months of standing. As can be seen from the figures, the original phthalocyanine blue, after ultrasonic dispersion in water, quickly began to aggregate, with particles becoming larger and precipitating; the solution became clear and transparent after 48 hours. The phthalocyanine blue modified with the superdispersant coating remained uniformly dispersed in water after two months of standing, with only a small amount precipitating.

[0097] (7) Heat stability test of modified phthalocyanine blue pigment

[0098] The phthalocyanine blue particles, both before and after modification, were placed in an 80℃ environment for 6 hours. After being removed and cooled to room temperature, their average particle size was measured. This cycle was repeated four times, and the results are as follows: Figure 7 As shown, the blue bar chart represents the modified phthalocyanine blue obtained in Example 2.4, and the orange bar chart represents the original phthalocyanine blue.

[0099] As shown in the figure, the average particle size of the unmodified phthalocyanine blue particles increased significantly and became unevenly distributed under heating. The modified phthalocyanine blue particles maintained a relatively small particle size after the first two heating cycles, with little change. With continued heating, the particle size gradually increased. This is because high temperatures increase the Brownian motion rate and kinetic energy of the particles, significantly increasing the probability of collisions between particles. Furthermore, increased temperature weakens the binding force between the superdispersant and phthalocyanine blue, reducing the dispersion stability of the system.

[0100] In summary, the superdispersant prepared by this invention can improve the dispersion performance of modified phthalocyanine blue, resulting in a smaller particle size, higher color intensity, and better dispersion stability in water, thus expanding its application range and increasing its application value.

Claims

1. An anionic superdispersant, characterized in that, It is copolymerized from styrene, a polymerizable monomer and a crosslinking agent, wherein the polymerizable monomer is selected from sodium vinyl phosphate, sodium acrylate, sodium vinyl benzoate or sodium styrene sulfonate; and the crosslinking agent is selected from N,N-methylenebisacrylamide or divinylbenzene.

2. The anionic superdispersant according to claim 1, wherein, The polymerizable monomer is sodium acrylate, the crosslinking agent is N,N-methylenebisacrylamide, and the structural formula of the hyperdispersant is: Where 2≤x≤5, 10≤y≤50, and 10≤z≤50.

3. The anionic superdispersant according to claim 1 or 2, wherein, The superdispersant is prepared from the following raw materials: Acrylic acid 2.4-2.6 parts by weight, sodium hydroxide 1.2-1.5 parts by weight, potassium persulfate 0.1-0.2 parts by weight, N,N-methylenebisacrylamide 0.2-0.3 parts by weight, and styrene 1-5 parts by weight.

4. The method for preparing the anionic superdispersant according to claim 3, characterized in that, Includes the following steps: (1) Disperse acrylic acid, sodium hydroxide, sodium persulfate and N,N-methylenebisacrylamide in a solvent to obtain an aqueous phase; (2) Add styrene to the aqueous phase and ultrasonically emulsify to obtain an oil-in-water emulsion; (3) The oil-in-water emulsion is polymerized under nitrogen bubbling conditions to obtain the anionic superdispersant.

5. A modified phthalocyanine blue, characterized in that, Including phthalocyanine blue and the anionic superdispersant as described in any one of claims 1-3 coated on the surface of phthalocyanine blue.

6. The method for preparing the modified phthalocyanine blue according to claim 5, characterized in that, Includes the following steps: (1) Disperse acrylic acid, sodium hydroxide, sodium persulfate and N,N-methylenebisacrylamide in a solvent to obtain an aqueous phase; (2) Add styrene and phthalocyanine blue raw materials to the aqueous phase and emulsify by ultrasonication to obtain phthalocyanine blue pre-dispersion; (3) The phthalocyanine blue pre-dispersion was prepolymerized at 40~50℃ under nitrogen bubbling conditions, and then polymerized at 60~80℃ to obtain the modified phthalocyanine blue.

7. The preparation method according to claim 6, wherein, The mass ratio of the phthalocyanine blue raw material to the acrylic acid is (1.5~2.5):

1.

8. The preparation method according to claim 6, wherein, The dispersion process described in step (1) is carried out under stirring conditions at a stirring speed of 400-500 rpm.

9. The modified phthalocyanine blue according to claim 5, wherein, The contact angle of water on the modified phthalocyanine blue surface is 50~75°.

10. The application of the anionic superdispersant of claim 1 or 2, or the modified phthalocyanine blue of claim 5 or 9, in the fields of coatings, inks, plastics, rubber, cosmetics, or pharmaceuticals.

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