Preparation method and application of nano organic pigments with different crystal forms

Abstract

The invention relates to the field of organic pigments, and discloses a preparation method and application of nano organic pigments with different crystal forms. The preparation method comprises the following steps: 1) dissolving an organic pigment crude product in a good solvent, and adding inorganic salt for activation; 2) dropwise adding a poor solvent at a gradient rate, adding a crystal form guiding agent, and inducing formation of a crystal nucleus; wherein the alpha crystal form directing agent is magnesium stearate; the beta crystal form directing agent is dibutyl phthalate; the gamma crystal form directing agent is polyethylene glycol; the initial gradient rate is 0.5-1 mL / min, and the gradient rate is increased by 0.2-0.3 mL / min every 8-12 min; 3) ultrasonic treatment; 4) cooling, and adding a surface modifier for surface modification; according to the preparation method, the nanometer organic pigment with the target crystal form can be accurately obtained through process regulation and control, the nanometer organic pigment is uniform in particle size distribution, good in dispersity, good in heat-resistant stability and high in color and luster strength, and the nanometer organic pigment has the advantages of being good in flocculation-resistant stability and weather resistance after a coating is formed.

Description

Technical Field

[0001] This invention relates to the field of organic pigments, and more particularly to a method for preparing and applying nano-organic pigments with different crystal forms. Background Technology

[0002] Organic pigments are widely used in coatings, inks, plastics, and printing and dyeing due to their bright colors, strong tinting strength, and low toxicity. However, traditional organic pigments have certain technical drawbacks, such as single and unstable crystal forms, poor dispersion, and low surface activity. Existing methods for preparing organic pigments mainly include ball milling, kneading, solvent treatment, and surface modification. Although these methods are widely used, they still have the following problems: pigments prepared by ball milling or kneading often have unstable crystal forms, are prone to reversion, and have uneven particle size distribution, resulting in poor dispersibility and unstable tinting strength; solvent recrystallization relies on large amounts of organic solvents, which is not conducive to environmental protection and industrialization, and the crystal form controllability is poor, requiring high standards for solvent, temperature, and concentration; although surface treatment can improve dispersibility, it contributes only to the crystal form transformation of the pigment itself and cannot fundamentally change the crystal lattice structure; moreover, the coating layer may affect the tinting performance and durability of the pigment itself.

[0003] Patent CN113683905 discloses a method for controlling the crystal form of nano-pigments. This method involves pre-dispersing the pigment using a kneader and then dispersing it further using a sand mill with the addition of a specific aqueous photosensitive resin, thereby achieving the preparation of crystalline pigments. However, this requires specialized equipment, and the cost of the aqueous photosensitive resin is relatively high. Patent CN111621168A discloses a method for the mixed crystal formation of quinacridone pigments. The resulting crude pigment is placed in a sealed reactor for crystallization and maturation, after which surface modification can be performed as needed. However, this method only applies to quinacridone pigments and cannot control the target crystal form.

[0004] Therefore, there is an urgent need for a new preparation method that can produce organic pigments with target crystal form and good particle size distribution in a low-energy, stable and efficient manner to improve their dispersibility, color intensity, stability and other properties. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for preparing and applying nano-organic pigments with different crystalline forms. This invention allows for precise control of the process to obtain nano-organic pigments with the target crystalline form. These nano-organic pigments exhibit uniform particle size distribution, good dispersibility, good thermal stability, high color intensity, and, after forming a coating, possess anti-flocculation stability and good weather resistance.

[0006] The specific technical solution of the present invention includes: In a first aspect, the present invention provides a method for preparing nano-organic pigments of different crystal forms, comprising the following steps: 1) Pretreatment: Dissolve the crude organic pigment in a good solvent for organic pigments, add inorganic salt to activate it, and form a homogeneous solution; the organic pigment is phthalocyanine pigment, azo pigment or quinacridone pigment.

[0007] In step 1), the inorganic salt acts as an activator and collides with the organic pigment under shear force during the mixing and activation process. At the moment of collision, the salt crystal "concentrates" mechanical energy and transfers it to the organic pigment particles, enabling them to overcome the lattice potential barrier and transform from a metastable crystal form with high internal energy to a crystal form with low internal energy. At the same time, the grain size decreases, the defects increase, and the surface activity increases.

[0008] 2) Gradient solvent mixing: Add the undesirable solvent of the organic pigment at a gradient dropping rate, and add a crystal-directing agent to induce crystal nucleation; wherein: the α-crystal-directing agent is magnesium stearate; the β-crystal-directing agent is dibutyl phthalate; and the γ-crystal-directing agent is polyethylene glycol; the gradient dropping rate is initially 0.5-1 mL / min, and increases by 0.2-0.3 mL / min every 8-12 min.

[0009] In step 2), firstly, this invention discovers that for specific organic pigments such as phthalocyanine pigments, azo pigments, and quinacridone pigments, when magnesium stearate, dibutyl phthalate, and polyethylene glycol are selected as crystal form guiding agents, three target crystal forms, α, β, and γ, can be obtained after crystallization, respectively. The above three crystal form guiding agents guide the directional growth of crystal nuclei through specific effects, ensuring the precision of crystal form control. Secondly, this invention further discovers that by combining a special gradient drop-feeding process with poor solvents, high-quality crystals with high dispersibility, high heat resistance and stability, and good particle size uniformity can be obtained.

[0010] The core purpose of this invention, employing a gradient dropping process, is to achieve "variable-rate nucleation and controlled growth" of crystal forms, thereby obtaining pigment particles with small particle size, narrow distribution, and regular morphology. The principle is as follows: The core principle of gradient dropping with a poor solvent is to gradually regulate the supersaturation of the system by controlling the dropping rate of the poor solvent, thereby achieving directional induction of crystal nuclei and ensuring their stable growth. In the initial stage, the system has a high proportion of good solvent and high pigment solubility. Dropping the poor solvent at a low rate can slowly reduce the pigment solubility, allowing the system to gently reach the "critical supersaturation," creating conditions for the specific binding of crystal form guiding agents and pigment molecules, inducing the directional formation of target crystal nuclei. In the acceleration stage, as the target crystal nuclei are generated, appropriately increasing the dropping rate can maintain a stable supersaturation of the system, providing continuous power for crystal nuclei growth, while avoiding insufficient supersaturation that would cause crystal nuclei growth stagnation. Finally, after the crystal nuclei complete directional growth, moderately high-speed dropping can quickly complete the crystal form conversion of the remaining pigment, improving production efficiency.

[0011] During the research process, this invention discovered that if a uniform dropwise addition process is used: if the uniform rate is too low (e.g., 0.5 mL / min): the supersaturation of the system increases too slowly, resulting in insufficient kinetics for crystal nucleus generation and growth, and a significantly prolonged reaction cycle; moreover, prolonged low supersaturation can easily lead to insufficient adsorption of the crystal-directing agent, potentially inducing the formation of impurities and reducing the purity of the target crystal form; if the uniform rate is too high (e.g., 2 mL / min): the supersaturation increases sharply in the initial stage, causing pigment molecules to rapidly aggregate and precipitate, preventing the crystal-directing agent from binding with the target crystal nucleus in time, resulting in the formation of a large number of disordered crystal nuclei and ultimately forming a mixed crystal form; at the same time, the crystal nuclei are prone to agglomeration and have poor dispersibility; if the uniform rate is moderate (e.g., 1 mL / min): although the above extreme problems can be avoided, it cannot adapt to the different stages of crystal nucleus induction and growth, resulting in uneven crystal nucleus growth, insufficient crystallinity of the product, and reduced weather resistance and heat resistance.

[0012] Furthermore, the rate of gradient dropping is also crucial: if the gradient dropping acceleration rate is too high, the rapid increase in speed will lead to a sharp rise in the supersaturation of the system, exceeding the control capability of the crystal form directing agent. In addition to the target crystal nucleus, a large number of non-target crystal nuclei will be generated, resulting in a decrease in the purity of the target crystal form. The crystal nucleus generation rate far exceeds the growth rate, and a large number of small crystal nuclei are prone to collision and aggregation, resulting in a wide particle size distribution. Subsequent ultrasound cannot completely break up the aggregation, resulting in poor product dispersibility and inability to meet the uniform coloring requirements of coatings and inks. The local concentration of undesirable solvents is too high, causing a sudden change in the viscosity of the system. The stirring rate cannot achieve uniform mixing, resulting in a non-uniform state, which further deteriorates the crystal form and dispersibility. Conversely, if the gradient dropping acceleration rate is too low, the supersaturation increases slowly, and the crystal nucleus growth cycle is significantly prolonged. Moreover, under a long-term low supersaturation environment, the crystal form directing agent may undergo molecular conformational changes or be adsorbed by trace impurities in the system, losing its directional induction effect on the target crystal nucleus, leading to the appearance of mixed crystals. Furthermore, the crystal nucleus growth motive force is continuously insufficient, and defects such as vacancies and dislocations are easily generated inside the crystal, resulting in a decrease in heat resistance.

[0013] 3) Ultrasonic treatment to achieve crystal form transformation.

[0014] In step 2), the organic pigment target crystal nuclei are oriented and formed by solvent gradient mixing, laying the foundation for precise crystal form control. On this basis, in step 3), the present invention combines ultrasonic cavitation effect to help accelerate the crystal form transformation process and suppress the generation of impurity crystal forms, thereby improving the purity and crystallinity of the target crystal form.

[0015] 4) Surface modification: Cool down and add surface modifier to modify the surface.

[0016] In step 4), the in-situ surface modifier can effectively prevent crystal reversal by physically adsorbing or chemically bonding pigment crystals; at the same time, the relatively mild temperature after cooling can avoid high-temperature crystal degradation.

[0017] 5) Post-processing yields the target crystalline organic pigment. The average particle size is 100-250 nm, and the particle size distribution (PDI) is 0.1-0.25.

[0018] Preferably, in step 1), the crude organic pigment is 10-20 parts by weight, the good solvent is 50-80 parts, and the inorganic salt is 0.1-1 parts.

[0019] Preferably, in step 1), the good solvent is selected from N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and dichloromethane (DCM); the inorganic salt is selected from sodium chloride, potassium chloride, sodium sulfate, and calcium chloride.

[0020] Preferably, in step 1), the dissolution temperature is 40-60°C.

[0021] Preferably, in step 2), the crystal-directing agent is 0.5-3 parts; the volume ratio of the good solvent to the bad solvent is 1-1.6:0.6-1.2.

[0022] In the system of this invention, by controlling the amount of crystal-directing agent within the above-mentioned range, the organic pigment exhibits the highest crystallinity, thus yielding a single high-crystallinity crystal form. Too low a content leads to insufficient crystal nuclei, poor crystallinity, and products that are mostly amorphous or heteromorphic, resulting in a decreased yield of the target crystal form. Too high a content leads to the coexistence of non-target crystal forms, decreased product purity, excessive grain refinement, abnormally increased specific surface area, increased secondary packing pores, and increased diffusion resistance; it also deteriorates performance when adsorbing long-chain molecules.

[0023] In this invention, the core function of the good solvent is to dissolve the crude organic pigment to form a homogeneous solution, providing a basis for the directional growth of crystal nuclei. The function of the poor solvent is to reduce the pigment solubility and induce crystal nuclei precipitation through gradient dropwise addition. The core logic of controlling the ratio of the two is to balance "sufficient pigment dissolution" and "directional crystal nuclei precipitation efficiency," ensuring that the system can form a single target crystal nucleus under mild conditions, avoiding the formation of mixed crystal forms, and providing a stable suspension system for subsequent ultrasound-assisted crystal form conversion. The solvent ratio corresponding to different crystal forms is the result of precise optimization based on the thermodynamic stability of different crystal forms and the differences in the solubility of organic pigments in solvents. Within the above ratio range, the crude organic pigment can be completely dissolved (good solvent solubility ≥10g / 100mL), while the amount of poor solvent added can precisely reduce the pigment solubility to the "critical precipitation state," achieving the directional growth of target crystal nuclei in conjunction with the crystal form guiding agent.

[0024] If the content of good solvent is too high, the system will have an excessively strong ability to dissolve pigments, and the poor solvent will not be able to effectively reduce the pigment solubility. Even if gradient addition is completed, it will be difficult to reach the conditions for crystal nucleation, resulting in very few crystal nuclei. Subsequent ultrasonic-assisted conversion will lack sufficient crystal nuclei, leading to insufficient purity of the target crystal form and easy formation of mixed crystal forms. If the content of good solvent is too low, the crude organic pigment will not be completely dissolved, leaving undissolved solid particles. These particles will act as impurity crystal nuclei, inducing the formation of non-target crystal forms and disrupting the homogeneity of the solution, resulting in disordered crystal nucleus growth during subsequent gradient addition. Moreover, the crystal nuclei are prone to agglomeration and cannot be precisely controlled by crystal-directing agents, resulting in uneven particle size, numerous crystal defects, and significantly reduced dispersibility and heat resistance in the final product. Similarly, if the content of poor solvent is too high, the viscosity of the suspension will increase sharply, making it impossible to achieve uniform mixing under stirring. The ultrasonic effect will also be weakened due to viscosity, failing to effectively accelerate crystal form conversion, resulting in insufficient crystallinity in the final product. If the content of undesirable solvents is too low, it cannot provide sufficient solubility gradient driving force for crystal nucleus growth, making it difficult to complete crystal transformation and resulting in decreased production efficiency. Furthermore, if the surface modification effect is poor and the crystal concentration in the suspension is too low, the surface modifier cannot be uniformly coated on the crystal surface, failing to prevent crystal reversal and improve dispersibility.

[0025] Preferably, in step 2), the undesirable solvent is selected from deionized water, ethanol, and ethyl acetate.

[0026] Preferably, in step 3), the conditions for ultrasonic treatment are: power 150-300W, frequency 20-40kHz, and time 30-90min. Preferably, in step 4), the surface modifier is selected from silane coupling agents and polyether-modified polysiloxanes.

[0027] Preferably, in step 4), the surface modifier is 1-5 parts.

[0028] The core function of the surface modifier in this invention is to uniformly coat the pigment crystal surface through physical adsorption or chemical bonding, forming a stable modified layer. On one hand, this layer blocks the active sites on the surface of the organic pigment crystals, preventing crystal reversal; on the other hand, it reduces the surface energy of the pigment, decreases particle agglomeration, and improves dispersion stability. The dosage of 1-5 parts is controlled to match the number of surface active sites on the pigment crystals, achieving complete and effective coating, ensuring the full utilization of the modified function, and avoiding performance degradation or cost waste. If the dosage is too low, the surface modifier cannot completely cover the active sites on the pigment crystal surface, leaving some active sites exposed. This can easily lead to crystal reversal during subsequent storage or application, resulting in a decrease in the purity of the target crystal form. An incomplete modified layer cannot effectively reduce the pigment surface energy; van der Waals forces between particles cause agglomeration, leading to increased particle size and poor dispersibility. Uncoated pigment surfaces are easily exposed to the external environment, resulting in decreased weather resistance and heat resistance. If too much of it is used, it cannot be fully adsorbed onto the pigment surface. The unadsorbed free surface modifier will entangle and agglomerate, forming new impurity particles that combine with the pigment particles, leading to increased system viscosity and a significant decrease in dispersibility. Furthermore, excessive modifier will increase raw material costs, is difficult to completely remove through subsequent washing, and easily remain in the finished product, causing a decline in the pigment's core properties such as tinting strength and color.

[0029] Preferably, in step 4), the cooling is to cool to 30-40℃; the surface modification conditions are: stirring speed of 800-1000 r / min and time of 20-40 min.

[0030] Preferably, in step 5), the post-processing includes: filtration, washing, and vacuum drying.

[0031] Secondly, the present invention provides the application of the nano-organic pigments obtained by the above preparation method in coatings, inkjet inks, food packaging printing inks, plastic colorants, and textile dyeing dyes.

[0032] Preferably, the amount of the nano-organic pigment added is 5-20 wt% of the coating, 3-15% of the inkjet ink, 0.8-5 wt% of the plastic colorant, 2-8 wt% of the food packaging printing ink, and 8-20 wt% of the textile printing dye. Compared with the prior art, the beneficial effects of the present invention are: (1) For specific organic pigments such as phthalocyanine pigments, azo pigments and quinacridone pigments, the present invention selects magnesium stearate, dibutyl phthalate and polyethylene glycol as crystal form guiding agents. The above three crystal form guiding agents guide the directional growth of crystal nuclei through specific action, ensuring the precision of crystal form control, and ensuring that the three target crystal forms α, β and γ can be obtained after crystallization, and the purity is high.

[0033] (2) By combining a special gradient drop-drop process with a poor solvent, the present invention can obtain high-quality crystals with high dispersibility, high heat resistance and stability and good particle size uniformity.

[0034] (3) This invention solves the problem of mixed crystal forms in traditional methods by using solvent gradient induction and specific combination of crystal form guiding agent; low energy consumption and high efficiency: the reaction temperature is low, which greatly reduces energy consumption, and ultrasonic assistance shortens the crystal form conversion time; simultaneous surface modification: in-situ coating of surface modifier can improve the heat resistance stability of pigments; environmentally friendly process: the solvent has a high recyclability rate and no harmful additive residues, which meets the requirements of green chemical industry.

[0035] (4) The nano-organic pigments of different crystal forms prepared by the present invention have excellent color stability, dispersibility and weather resistance, and can be widely used in coatings, inks, plastic coloring, textile printing and dyeing and other fields. The preparation process is simple, energy consumption is low, suitable for industrial production, and has broad application prospects. Attached Figure Description

[0036] Figure 1 The image shows the X-ray crystal diffraction pattern of the sample obtained in Example 1.

[0037] Figure 2 This is a transmission electron microscope (TEM) image of the sample obtained in Example 1.

[0038] Figure 3 The image shows the X-ray crystal diffraction pattern of the sample obtained in Example 2.

[0039] Figure 4 This is a transmission electron microscope (TEM) image of the sample obtained in Example 2.

[0040] Figure 5 The image shows the X-ray crystal diffraction pattern of the sample obtained in Example 3.

[0041] Figure 6 This is a transmission electron microscope (TEM) image of the sample obtained in Example 3.

[0042] Figure 7 The particle size distribution diagrams are for the samples obtained in Example 1 and Comparative Examples 1-3.

[0043] Figure 8 The graph shows the heat resistance stability of the samples obtained in Example 1 and Comparative Examples 1-3.

[0044] Figure 9 The particle size distribution diagrams are for the samples obtained in Example 2 and Comparative Examples 4-6.

[0045] Figure 10 The graph shows the heat resistance stability of the samples obtained in Example 2 and Comparative Examples 4-6.

[0046] Figure 11The particle size distribution diagrams are for the samples obtained in Example 3 and Comparative Examples 7-9.

[0047] Figure 12 The graph shows the heat resistance stability of the samples obtained in Example 3 and Comparative Examples 7-9. Detailed Implementation

[0048] The present invention will be further described below with reference to embodiments.

[0049] General Implementation Examples In a first aspect, a method for preparing nano-organic pigments of different crystal forms includes the following steps: 1) Pretreatment: Dissolve the crude organic pigment in a good solvent, add inorganic salt to activate it, and form a homogeneous solution; the organic pigment is phthalocyanine pigment, azo pigment or quinacridone pigment.

[0050] In some preferred embodiments, in step 1), the crude organic pigment is 10-20 parts by weight, the good solvent is 50-80 parts, and the inorganic salt is 0.1-1 parts.

[0051] In some preferred embodiments, in step 1), the good solvent is selected from N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and dichloromethane (DCM); the inorganic salt is selected from sodium chloride, potassium chloride, sodium sulfate, and calcium chloride.

[0052] In some preferred embodiments, in step 1), the melting temperature is 40-60°C.

[0053] 2) Gradient solvent mixing: Add the unsuitable solvent dropwise at a gradient drop rate, and add a crystal-directing agent to induce crystal nucleation; wherein: the α-crystal-directing agent is magnesium stearate; the β-crystal-directing agent is dibutyl phthalate; and the γ-crystal-directing agent is polyethylene glycol; the gradient drop rate is initially 0.5-1 mL / min, and increases by 0.2-0.3 mL / min every 8-12 min.

[0054] In some preferred embodiments, in step 2), the crystal-directing agent is 0.5-3 parts; the volume ratio of the good solvent to the bad solvent is 1-1.5:1.

[0055] In some preferred embodiments, in step 2), the undesirable solvent is selected from deionized water, ethanol, and ethyl acetate.

[0056] 3) Ultrasonic treatment to achieve crystal form transformation.

[0057] In some preferred embodiments, in step 3), the conditions for ultrasonic treatment are: power 150-300W, frequency 20-40kHz, and time 30-90min. 4) Surface modification: Cool down and add surface modifier to modify the surface.

[0058] In some preferred embodiments, in step 4), the surface modifier is selected from silane coupling agents and polyether-modified polysiloxanes.

[0059] In some preferred embodiments, in step 4), the surface modifier is 1-5 parts.

[0060] In some preferred embodiments, in step 4), the cooling is to cool to 30-40°C; the surface modification conditions are: stirring speed of 800-1000 r / min, time of 20-40 min.

[0061] 5) Post-processing yields the target crystalline organic pigment. The average particle size (PDI) is 100-250 nm, and the particle size distribution is 0.1-0.25.

[0062] In some preferred embodiments, step 5) includes post-processing including: filtration, washing, and vacuum drying.

[0063] In some preferred embodiments, the vacuum drying temperature is 60-80°C.

[0064] Secondly, the nano-organic pigments obtained by the above preparation method are used in coatings, inkjet inks, food packaging printing inks, plastic colorants, and textile dyeing dyes.

[0065] In some preferred embodiments, the amount of the nano-organic pigment added is 5-20 wt% of the coating, 3-15% of the inkjet ink, 0.8-5 wt% of the plastic colorant, 2-8 wt% of the food packaging printing ink, and 10-18 wt% of the textile printing dye. In some more preferred embodiments, the coating is a water-based environmentally friendly coating, automotive original paint, or anti-corrosion coating; the inkjet ink is a water-based inkjet ink or a UV-curable inkjet ink; and the plastic substrate for which the plastic colorant is applied is one or more of polypropylene, polycarbonate, resin, and polyamide.

[0066] Specific embodiments and comparative examples (I) Preparation of quinacridone nanoparticles with different crystal forms Example 1 (Type α) Take 15g of quinacridone-based disperse pigment red crude product (type PR122, Hangzhou Baihe Faber-Castell Pigment Co., Ltd.) and add it to 65g of DMF. Stir at 50℃ and 400r / min for 45min until the pigment is completely dissolved. Add 0.3g of sodium chloride and continue stirring for 10min to activate the system. Add 45g of deionized water dropwise to the above solution at an initial rate of 0.8mL / min, increasing by 0.2mL / min every 10min, while maintaining a stirring rate of 600r / min. When the system became slightly turbid, 1.5 g of magnesium stearate was added, and stirring was continued for 25 min. The suspension was then transferred to an ultrasonic machine with an ultrasonic power of 180 W, a frequency of 30 kHz, a temperature of 50 °C, and a time of 30 min, while maintaining a stirring rate of 400 r / min. The system temperature was then lowered to 35 °C, and 2.5 g of silane coupling agent KH-550 was added. The mixture was stirred at 900 r / min for 30 min, then filtered and separated. The filter cake was washed four times with ethanol and dried under vacuum at 70 °C for 18 h to obtain α-type quinacridone nanoparticles.

[0067] like Figure 1 The image shown is the X-ray crystal diffraction pattern of the product of this embodiment. Figure 2 The image shown is a transmission electron microscope (TEM) image of the product from this embodiment. It can be seen that the α-type quinacridone nanoparticles are needle-shaped.

[0068] Comparative Example 1 (α type) The only difference from Example 1 is that deionized water is added dropwise at a uniform rate. The specific steps are as follows: 15g of crude quinacridone was added to 65g of DMF and stirred at 50℃ and 400r / min for 45min until the pigment was completely dissolved. 0.3g of sodium chloride was added and stirring was continued for 10min to activate the system. 45g of deionized water was added dropwise to the above solution at a rate of 1.2mL / min, while maintaining a stirring rate of 600r / min. When the system became slightly turbid, 1.5g of magnesium stearate was added and stirring was continued for 25min. The suspension was transferred to an ultrasonic machine with an ultrasonic power of 180W, a frequency of 30kHz, a temperature of 50℃, and a time of 30min, while maintaining a stirring rate of 400r / min. The system temperature was then lowered to 35℃, and 2.5g of silane coupling agent KH-550 was added. After stirring at 900r / min for 30min, the mixture was filtered and separated. The filter cake was washed four times with ethanol and dried under vacuum at 70℃ for 18h to obtain α-type quinacridone nano-pigment.

[0069] Comparative Example 2 (α type) The only difference from Example 1 is that the dropping rate of deionized water is increased by 0.05 mL / min every 10 minutes. The specific steps are as follows: 15g of crude quinacridone was added to 65g of DMF and stirred at 50℃ and 400r / min for 45min until the pigment was completely dissolved. 0.3g of sodium chloride was added and stirring was continued for 10min to activate the system. 45g of deionized water was added dropwise to the above solution at an initial rate of 0.8mL / min, increasing by 0.05mL / min every 10min, while maintaining a stirring rate of 600r / min. When the system became slightly turbid, 1.5g of magnesium stearate was added and stirring was continued for 25min. The suspension was transferred to an ultrasonic machine, and the ultrasonic power was 180W, frequency 30kHz, temperature 50℃, time 30min, and stirring rate maintained at 400r / min. Then the system temperature was lowered to 35℃, 2.5g of silane coupling agent KH-550 was added, and the mixture was stirred at 900r / min for 30min. After filtration, the filter cake was washed four times with ethanol and dried under vacuum at 70℃ for 18h to obtain α-type quinacridone nano-pigment.

[0070] Comparative Example 3 (α type) The only difference from Example 1 is that the dropping rate of deionized water is increased by 0.5 mL / min every 10 min. The specific steps are as follows: 15g of crude quinacridone was added to 65g of DMF and stirred at 50℃ and 400r / min for 45min until the pigment was completely dissolved. 0.3g of sodium chloride was added and stirring was continued for 10min to activate the system. 45g of deionized water was added dropwise to the above solution at an initial rate of 0.8mL / min, increasing by 0.5mL / min every 10min, while maintaining a stirring rate of 600r / min. When the system became slightly turbid, 1.5g of magnesium stearate was added and stirring was continued for 25min. The suspension was transferred to an ultrasonic machine, and the ultrasonic power was 180W, frequency 30kHz, temperature 50℃, time 30min, and stirring rate maintained at 400r / min. Then the system temperature was lowered to 35℃, 2.5g of silane coupling agent KH-550 was added, and the mixture was stirred at 900r / min for 30min. After filtration, the filter cake was washed four times with ethanol and dried under vacuum at 70℃ for 18h to obtain α-type quinacridone nano-pigment.

[0071] Performance Comparison Particle size and heat resistance stability tests were performed on the samples obtained in Example 1 and Comparative Examples 1-3. The heat resistance stability test method was as follows: the samples were placed in an oven at 60°C, and samples were taken every 24 hours for a total of 5 times. The test results are as follows. Figure 7-8 As shown in Table 1: Table 1 pass Figure 7 As can be seen from the data comparison in Table 1: The difference between Comparative Example 1 and Example 1 is that a uniform droplet addition method was used. The results showed that the particle size and distribution increased and a bimodal distribution appeared. The reason for this is that the local supersaturation of the system increased instantaneously in the early stage, generating a large number of small crystal nuclei; in the later stage, the supersaturation decreased rapidly, the number of crystal nuclei was fixed, growth was limited, and finally a bimodal distribution was formed.

[0072] The difference between Comparative Example 2 and Example 1 lies in the use of a lower drop rate acceleration. The results showed an increase in particle size, a wider distribution, and the appearance of "small tails." The reason for this is that the system has a lower saturation, resulting in a low nucleation rate. The growth mainly relies on a small number of crystal nuclei growing slowly, leading to an increase in particle size.

[0073] The difference between Comparative Example 3 and Example 1 is that the drop rate was too high. The results showed that the particle size increased and the particle size distribution increased sharply. The reason for this is that the added deionized water did not have enough time to diffuse, the local supersaturation increased, and homogeneous nucleation occurred instantly, resulting in crystal nuclei of different sizes, larger particle size and easy agglomeration.

[0074] In addition, through Figure 8 A comparison of the heat resistance data shows that the heat resistance of samples 1-3 is significantly worse than that of Example 1.

[0075] Example 2 (β type) 15g of crude quinacridone was added to 60g of DMSO and stirred at 55℃ and 450r / min for 50min until completely dissolved. 0.3g of potassium chloride was added and stirred for 10min to complete activation. 50g of ethanol was added dropwise at an initial rate of 1mL / min, increasing by 0.3mL / min every 10min, while maintaining a stirring rate of 700r / min. After the system became turbid, 2g of dibutyl phthalate was added and stirring was continued for 30min. Ultrasonic treatment was performed at 220W power, 25kHz frequency, and 55℃ for 60min, with a stirring rate of 450r / min. Subsequently, the temperature was lowered to 35℃, 3g of polyether-modified polysiloxane was added, and the mixture was stirred at 950r / min for 35min. The mixture was then filtered, the filter cake was washed 5 times with deionized water, and vacuum dried at 75℃ for 20h to obtain β-type quinacridone nano-pigment.

[0076] like Figure 3 The image shown is the X-ray crystal diffraction pattern of the product of this embodiment. Figure 4 The image shown is a transmission electron microscope (TEM) image of the product of this embodiment.

[0077] Comparative Example 4 (β type) The only difference from Example 2 is that ethanol is added dropwise at a uniform rate. The specific steps are as follows: 15g of crude quinacridone was added to 60g of DMSO and stirred at 55℃ and 450r / min for 50min until completely dissolved. 0.3g of potassium chloride was added and stirred for 10min to complete activation. 50g of ethanol was added dropwise at a rate of 1.5mL / min while maintaining a stirring rate of 700r / min. After the system became turbid, 2g of dibutyl phthalate was added and stirring was continued for 30min. Ultrasonic treatment was performed at 220W, 25kHz, and 55℃ for 60min with a stirring rate of 450r / min. The temperature was then lowered to 35℃, 3g of polyether-modified polysiloxane was added, and the mixture was stirred at 950r / min for 35min before filtration. The filter cake was washed 5 times with deionized water and dried under vacuum at 75℃ for 20h to obtain β-type quinacridone nano-pigment.

[0078] Comparative Example 5 (β type) The only difference from Example 2 is that the dropping rate of ethanol is increased by 0.1 mL / min every 10 min, and the specific steps are as follows: 15g of crude quinacridone was added to 60g of DMSO and stirred at 55℃ and 450r / min for 50min until completely dissolved. 0.3g of potassium chloride was added and stirred for 10min to complete activation. 50g of ethanol was added dropwise at an initial rate of 1mL / min, increasing by 0.1mL / min every 10min, while maintaining a stirring rate of 700r / min. After the system became turbid, 2g of dibutyl phthalate was added and stirring was continued for 30min. Ultrasonic treatment was performed at 220W power, 25kHz frequency, and 55℃ for 60min, with a stirring rate of 450r / min. Subsequently, the temperature was lowered to 35℃, 3g of polyether-modified polysiloxane was added, and the mixture was stirred at 950r / min for 35min. The mixture was then filtered, the filter cake was washed 5 times with deionized water, and vacuum dried at 75℃ for 20h to obtain β-type quinacridone nano-pigment.

[0079] Comparative Example 6 (β type) The only difference from Example 2 is that the ethanol dropping rate is increased by 0.4 mL / min every 10 min, and the specific steps are as follows: 15g of crude quinacridone was added to 60g of DMSO and stirred at 55℃ and 450r / min for 50min until completely dissolved. 0.3g of potassium chloride was added and stirred for 10min to complete activation. 50g of ethanol was added dropwise at an initial rate of 1mL / min, increasing by 0.4mL / min every 10min, while maintaining a stirring rate of 700r / min. After the system became turbid, 2g of dibutyl phthalate was added and stirring was continued for 30min. Ultrasonic treatment was performed at 220W power, 25kHz frequency, and 55℃ for 60min, with a stirring rate of 450r / min. Subsequently, the temperature was lowered to 35℃, 3g of polyether-modified polysiloxane was added, and the mixture was stirred at 950r / min for 35min. The mixture was then filtered, the filter cake was washed 5 times with deionized water, and vacuum dried at 75℃ for 20h to obtain β-type quinacridone nano-pigment.

[0080] Performance Comparison Particle size and heat resistance stability were tested on the samples obtained in Example 2 and Comparative Examples 4-6. The test results are as follows: Figure 9-10 As shown in Table 2: Table 2 pass Figure 9-10 As can be seen from the data comparison in Table 2, the experimental results of Comparative Examples 4-6 and Example 2 show similar trends to those in Table 1, indicating that the dropping process has a significant impact on the particle size distribution and heat resistance stability of the crystals.

[0081] Example 3 (γ type) 15g of crude quinacridone was added to 70g of DMF and stirred at 45℃ and 350r / min for 40min until completely dissolved. 0.2g of sodium chloride was added and stirred for 10min to complete activation. 40g of ethyl acetate was added dropwise at an initial rate of 0.6mL / min, increasing by 0.2mL / min every 10min, while maintaining a stirring rate of 650r / min. After the system became turbid, 1g of polyethylene glycol was added and stirring was continued for 20min. Ultrasonic treatment was performed at 250W power, 35kHz frequency, and 45℃ for 90min, with a stirring rate of 350r / min. Subsequently, the temperature was lowered to 30℃, 2g of KH-560 was added, and the mixture was stirred at 850r / min for 25min. The mixture was then filtered, the filter cake was washed three times with ethyl acetate, and vacuum dried at 65℃ for 16h to obtain γ-type quinacridone nano-pigment.

[0082] like Figure 5 The image shown is the X-ray crystal diffraction pattern of the product of this embodiment. Figure 6 The image shown is a transmission electron microscope (TEM) image of the product of this embodiment.

[0083] Comparative Example 7 (γ type) The only difference from Example 3 is that deionized water is added dropwise at a uniform rate. The specific steps are as follows: 15g of crude quinacridone was added to 70g of DMF and stirred at 45℃ and 350r / min for 40min until completely dissolved. 0.2g of sodium chloride was added and stirred for 10min to complete activation. 40g of ethyl acetate was added dropwise at a rate of 1mL / min while maintaining a stirring rate of 650r / min. After the system became turbid, 1g of polyethylene glycol was added and stirring was continued for 20min. Ultrasonic treatment was performed at 250W power, 35kHz frequency, and 45℃ for 90min with a stirring rate of 350r / min. The mixture was then cooled to 30℃, 2g of KH-560 was added, and the mixture was stirred at 850r / min for 25min before filtration. The filter cake was washed three times with ethyl acetate and dried under vacuum at 65℃ for 16h to obtain γ-type quinacridone nano-pigment.

[0084] Comparative Example 8 (γ type) The only difference from Example 3 is that the dropping rate of deionized water is increased by 0.1 mL / min every 10 minutes. The specific steps are as follows: 15g of crude quinacridone was added to 70g of DMF and stirred at 45℃ and 350r / min for 40min until completely dissolved. 0.2g of sodium chloride was added and stirred for 10min to complete activation. 40g of ethyl acetate was added dropwise at an initial rate of 0.6mL / min, increasing by 0.1mL / min every 10min, while maintaining a stirring rate of 650r / min. After the system became turbid, 1g of polyethylene glycol was added and stirring was continued for 20min. Ultrasonic treatment was performed at 250W power, 35kHz frequency, and 45℃ for 90min, with a stirring rate of 350r / min. Subsequently, the temperature was lowered to 30℃, 2g of KH-560 was added, and the mixture was stirred at 850r / min for 25min. The mixture was then filtered, the filter cake was washed three times with ethyl acetate, and vacuum dried at 65℃ for 16h to obtain γ-type quinacridone nano-pigment.

[0085] Comparative Example 9 (γ type) The only difference from Example 3 is that the dropping rate of deionized water is increased by 0.4 mL / min every 10 min. The specific steps are as follows: 15g of crude quinacridone was added to 70g of DMF and stirred at 45℃ and 350r / min for 40min until completely dissolved. 0.2g of sodium chloride was added and stirred for 10min to complete activation. 40g of ethyl acetate was added dropwise at an initial rate of 0.6mL / min, increasing by 0.4mL / min every 10min, while maintaining a stirring rate of 650r / min. After the system became turbid, 1g of polyethylene glycol was added and stirring was continued for 20min. Ultrasonic treatment was performed at 250W power, 35kHz frequency, and 45℃ for 90min, with a stirring rate of 350r / min. Subsequently, the temperature was lowered to 30℃, 2g of KH-560 was added, and the mixture was stirred at 850r / min for 25min. The mixture was then filtered, the filter cake was washed three times with ethyl acetate, and vacuum dried at 65℃ for 16h to obtain γ-type quinacridone nano-pigment.

[0086] Performance Comparison Particle size and heat resistance stability were tested on the samples obtained in Example 3 and Comparative Examples 7-9. The test results are as follows: Figure 11-12 As shown in Table 3: Table 3 pass Figure 11-12 As can be seen from the data comparison in Table 3, the experimental results of Comparative Examples 7-9 and Example 3 show similar trends to those in Tables 1-2, indicating that the dropping process has a significant impact on the particle size distribution and heat resistance stability of the crystals.

[0087] (II) Preparation of Phthalocyanine Blue Nanoparticles with Different Crystal Forms Example 4 12 parts of crude phthalocyanine blue were added to 60 parts of DMSO and stirred at 55℃ and 450 r / min for 55 min until the pigment was completely dissolved. 0.4 parts of potassium chloride were added and stirring was continued for 10 min to complete the system activation. 50 parts of ethanol were added dropwise to the above solution at an initial rate of 1.0 mL / min, increasing by 0.3 mL / min every 10 min, while maintaining a stirring rate of 700 r / min. When the system became slightly turbid, 2.0 parts of dibutyl phthalate were added and stirring was continued for 30 min. The suspension was transferred to an ultrasonic machine and ultrasonically treated for 60 min at a power of 220 W, a frequency of 25 kHz, and a temperature of 55℃, while maintaining a stirring rate of 450 r / min. Subsequently, the system temperature was lowered to 35℃, 3 parts of polyether-modified polysiloxane were added, and the mixture was stirred at 950 r / min for 35 min. After filtration, the filter cake was washed 5 times with ethanol and dried under vacuum at 75℃ for 20 h to obtain β-type phthalocyanine blue nano pigment.

[0088] Example 5 12 parts of crude phthalocyanine blue were added to 70 parts of DMF and stirred at 45℃ and 350 r / min for 40 min until the pigment was completely dissolved. 0.2 parts of sodium chloride were added and stirring was continued for 10 min to complete the system activation. 40 parts of ethyl acetate were added dropwise to the above solution at an initial rate of 0.6 mL / min, increasing by 0.2 mL / min every 10 min, while maintaining a stirring rate of 650 r / min. When the system became slightly turbid, 1.0 part of polyethylene glycol was added and stirring was continued for 20 min. The suspension was transferred to an ultrasonic machine and ultrasonically treated for 90 min at a power of 250 W, a frequency of 35 kHz, and a temperature of 45℃, while maintaining a stirring rate of 350 r / min. Subsequently, the system temperature was lowered to 30℃, 2 parts of KH-560 were added, and the mixture was stirred at 850 r / min for 25 min. After filtration, the filter cake was washed three times with ethyl acetate and dried under vacuum at 65℃ for 16 h to obtain γ-type phthalocyanine blue nano pigment.

[0089] (III) Preparation of Azo Red Nanoparticles with Different Crystal Forms Example 6 14 parts of crude azo pigment red were added to 65 parts of DMSO and stirred at 50℃ and 400 r / min for 45 min until the pigment was completely dissolved. 0.3 parts of sodium chloride were added and stirring was continued for 10 min to activate the system. 45 parts of ethanol were added dropwise to the above solution at an initial rate of 0.9 mL / min, increasing by 0.3 mL / min every 10 min, while maintaining a stirring rate of 700 r / min. When the system became slightly turbid, 1.8 parts of magnesium stearate were added and stirring was continued for 30 min. The suspension was transferred to an ultrasonic machine and ultrasonically treated for 50 min at a power of 220 W, a frequency of 25 kHz, and a temperature of 50℃, while maintaining a stirring rate of 400 r / min. Subsequently, the system temperature was lowered to 35℃, and 2.5 parts of polyether-modified polysiloxane were added. After stirring at 950 r / min for 35 min, the mixture was filtered and separated. The filter cake was washed 5 times with ethanol and dried under vacuum at 70℃ for 18 h to obtain α-type azo pigment red nano-pigment.

[0090] Example 7 14 parts of crude azo pigment red were added to 60 parts of DMSO and stirred at 55℃ and 450 r / min for 50 min until the pigment was completely dissolved. 0.3 parts of potassium chloride were added and stirring was continued for 10 min to activate the system. 50 parts of ethanol were added dropwise to the above solution at an initial rate of 1.0 mL / min, increasing by 0.3 mL / min every 10 min, while maintaining a stirring rate of 700 r / min. When the system became slightly turbid, 2.0 parts of dibutyl phthalate were added and stirring was continued for 30 min. The suspension was transferred to an ultrasonic machine and ultrasonically treated for 60 min at a power of 220 W, a frequency of 25 kHz, and a temperature of 55℃, while maintaining a stirring rate of 450 r / min. Subsequently, the system temperature was lowered to 35℃, 3 parts of polyether-modified polysiloxane were added, and the mixture was stirred at 950 r / min for 35 min. After filtration, the filter cake was washed 5 times with ethanol and dried under vacuum at 75℃ for 20 h to obtain β-type azo pigment red nano-pigment.

[0091] Example 8 14 parts of azo pigment red were added to 70 parts of DMF and stirred at 45℃ and 350 r / min for 40 min until the pigment was completely dissolved. 0.2 parts of sodium chloride were added and stirring was continued for 10 min to complete the system activation. 40 parts of ethyl acetate were added dropwise to the above solution at an initial rate of 0.6 mL / min, increasing by 0.2 mL / min every 10 min, while maintaining a stirring rate of 650 r / min. When the system became slightly turbid, 1.0 part of polyethylene glycol 400 was added and stirring was continued for 20 min. The suspension was transferred to an ultrasonic machine and ultrasonically treated for 90 min at a power of 250 W, a frequency of 35 kHz, and a temperature of 45℃, while maintaining a stirring rate of 350 r / min. Subsequently, the system temperature was lowered to 30℃, 2 parts of KH-560 were added, and the mixture was stirred at 850 r / min for 25 min. After filtration, the filter cake was washed three times with ethyl acetate and dried under vacuum at 65℃ for 16 h to obtain γ-type azo pigment red nanoparticles.

[0092] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0093] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing nano-organic pigments with different crystal forms, characterized in that... include: 1) Dissolve the crude organic pigment in a good solvent and activate it with inorganic salt; the organic pigment is a phthalocyanine pigment, azo pigment, or quinacridone pigment; 2) Add the poor solvent dropwise at a gradient rate, and add the crystal-directing agent to induce crystal nucleation; wherein: the α-crystal-directing agent is magnesium stearate; the β-crystal-directing agent is dibutyl phthalate; and the γ-crystal-directing agent is polyethylene glycol; the gradient rate is initially 0.5-1 mL / min, and increases by 0.2-0.3 mL / min every 8-12 min; 3) Ultrasonic treatment; 4) Cool down and add a surface modifier for surface modification; the surface modifier is selected from silane coupling agents and polyether-modified polysiloxanes; 5) Post-processing yields the target crystalline organic pigment; the average particle size is 100-250 nm, and the particle size distribution (PDI) is 0.1-0.

25.

2. The preparation method according to claim 1, characterized in that: In step 1), by weight, the crude organic pigment is 10-20 parts, the good solvent is 50-80 parts, and the inorganic salt is 0.1-1 parts.

3. The preparation method according to claim 1 or 2, characterized in that: In step 1), The good solvent is selected from N,N-dimethylformamide, dimethyl sulfoxide, and dichloromethane; The inorganic salt is selected from sodium chloride, potassium chloride, sodium sulfate, and calcium chloride; The melting temperature is 40-60℃.

4. The preparation method according to claim 2, characterized in that: In step 2), the crystal-directing agent is 0.5-3 parts; the volume ratio of the good solvent to the bad solvent is 1-1.5:

1.

5. The preparation method according to claim 1 or 4, characterized in that: In step 2), the undesirable solvent is selected from deionized water, ethanol, and ethyl acetate.

6. The preparation method according to claim 1, characterized in that: In step 3), the conditions for ultrasonic treatment are: power 150-300W, frequency 20-40kHz, and time 30-90min.

7. The preparation method according to claim 4, characterized in that: In step 4), the surface modifier is 1-5 parts.

8. The preparation method according to claim 1 or 7, characterized in that: In step 4), the cooling is to cool to 30-40℃; the surface modification conditions are: stirring speed of 800-1000 r / min, time of 20-40 min; In step 5), the post-processing includes: filtration, washing, and vacuum drying.

9. The application of the nano-organic pigments obtained by the preparation method according to any one of claims 1-8 in coatings, inkjet inks, printing inks, plastic colorants, and textile dyeing dyes.

10. The application according to claim 9, characterized in that: The amount of the nano-organic pigment added is 5-20 wt% of the coating, 3-15% of the inkjet ink, 0.8-5 wt% of the plastic colorant, 2-8 wt% of the printing ink, and 8-20 wt% of the textile dyeing dye.

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