Preparation method of a high-performance organic pigment for water-based printing ink

Abstract

The present invention discloses a preparation method of a high-performance organic pigment for water-based printing ink, comprising the following steps: dispersing the organic pigment in deionized water, adding an emulsifier to prepare an organic pigment dispersion; adding a hydrophilic monomer and a cross-linking monomer to the organic pigment dispersion, stirring, emulsifying evenly, adding an initiator, and stirring for reaction; after the reaction is completed, cooling, centrifuging, and washing to obtain the organic pigment with the first-layer coating; mixing a hydrophobic monomer and a functional monomer, adding an emulsifier and deionized water to prepare a microemulsion; dispersing the organic pigment with the first-layer coating in deionized water, dropping the microemulsion and the initiator, and stirring for reaction; after the reaction is completed, cooling, centrifuging, washing, and drying to obtain the high-performance organic pigment for water-based printing ink. The method of the present invention optimizes the performance of the organic pigment through a double-layer coating structure, enabling the organic pigment to have the advantages of dispersibility, lightfastness, high coloring power, water and oil resistance, and acid and alkali resistance.

Description

Technical Field

[0001] The invention relates to the technical field of organic pigments, and in particular to a method for preparing a high-performance organic pigment for water-based printing ink. Background Art

[0002] With the increasingly stringent environmental regulations and the promotion of green environmental protection concepts, water-based printing inks have become a widely used green alternative in the modern printing industry due to their low volatile organic compound (VOC) emissions, non-toxicity, harmlessness, and biodegradability. The performance of water-based printing inks is greatly affected by pigments, and the pigment's tinting power, transparency, dispersibility, and stability are directly related to the quality and application effect of the ink.

[0003] As a key component in water-based inks, organic pigments are widely used due to their bright colors, strong light resistance and good environmental protection. Compared with inorganic pigments, organic pigments have higher color saturation and good light transmittance, and are particularly suitable for ink products that require high transparency and bright colors. However, despite the significant advantages of organic pigments in water-based printing inks, there are still some problems that need to be solved, especially in terms of dispersion stability and tinting strength.

[0004] Organic pigments are usually insoluble in water, but are dispersed in the ink medium in the form of fine particles. Due to the high surface energy of pigment particles, they are easy to aggregate or precipitate in the liquid, causing the pigment dispersion to be unstable after standing for a period of time, resulting in particle aggregation and sedimentation, which affects the pigment's tinting power and color fastness. To solve this problem, the commonly used treatment method is to evenly disperse the pigment particles through ultrasonic or ball milling, but these methods are usually difficult to maintain the stability of the pigment for a long time, and the pigment may still precipitate and agglomerate.

[0005] In order to ensure good dispersibility of pigments in aqueous media, current technologies often rely on the addition of surfactants. Surfactants can adjust the surface polarity of pigments by adsorbing or coating on the surface of pigment particles, thereby improving the stability of pigment particles dispersed in water. Although this method effectively improves the dispersibility of pigments, the presence of surfactants also brings new problems. Surfactants are often physically adsorbed on the surface of pigment particles. Once the surfactant is desorbed, the surface polarity of the pigment particles may change, causing the pigment particles to re-aggregate or settle. This not only affects the dispersibility of the pigment, but may also cause the pigment's tinting power to decrease. Summary of the invention

[0006] Based on the problems existing in the background technology, the present invention provides a method for preparing high-performance organic pigments for water-based printing inks. The method of the present invention optimizes the performance of organic pigments through a double-layer coating structure, so that the organic pigments have the advantages of dispersibility, light resistance, high tinting strength, water and oil resistance, and acid and alkali resistance.

[0007] The present invention is implemented through the following technical solutions:

[0008] A preparation method of a high-performance organic pigment for water-based printing ink, comprising the following steps:

[0009] S1. Disperse the organic pigment in deionized water, add an emulsifier, and prepare an organic pigment dispersion;

[0010] S2. Add a hydrophilic monomer and a crosslinking monomer to the organic pigment dispersion, stir, emulsify evenly, continue to add an initiator, control the reaction temperature and time to ensure complete polymerization of the monomers;

[0011] S3. After the reaction is completed, cool to room temperature, centrifuge to remove unreacted monomers, and repeatedly wash the pigment particles with deionized water to obtain the organic pigment with the first layer of coating;

[0012] S4. Mix a hydrophobic monomer and a functional monomer, add an emulsifier and deionized water to prepare a microemulsion;

[0013] S5. Disperse the organic pigment with the first layer of coating in deionized water, control the reaction temperature, dropwise add the microemulsion and the initiator, control the reaction time to ensure complete polymerization of the monomers;

[0014] S6. After the reaction is completed, cool to room temperature, centrifuge to remove unreacted monomers, repeatedly wash the pigment particles with deionized water, and dry them under vacuum to obtain the high-performance organic pigment for water-based printing ink.

[0015] Further, the organic pigment is an azo pigment.

[0016] Further, the emulsifier in steps S1 and S4 is sodium dodecyl sulfate; the initiator in steps S2 and S5 is potassium persulfate.

[0017] Further, the hydrophilic monomers in step S2 are acrylic acid and methacrylic acid; the crosslinking monomer is ethylene glycol dimethacrylate.

[0018] Further, the mass ratio of acrylic acid, methacrylic acid and ethylene glycol dimethacrylate is (8-12):(5-8):1.

[0019] Further, the mass ratio of the total amount of the organic pigment and the hydrophilic monomer is 100:(5-7).

[0020] Further, the reaction temperature in step S2 is 60-70°C, and the reaction time is 3-5h.

[0021] Further, in step S4, the hydrophobic monomers are methyl methacrylate and butyl acrylate; the functional monomers are glycidyl acrylate and acrylamide; the mass ratio of methyl methacrylate, butyl acrylate, glycidyl acrylate and acrylamide is (5 - 8):(1.5 - 3):(1 - 3):1.

[0022] Further, the mass ratio of the total amount of the organic pigment and the hydrophobic monomers in the first layer coating is 100:(6 - 10).

[0023] Further, in step S5, the reaction temperature is 70 - 80 °C and the reaction time is 3 - 5 h.

[0024] Advantages of the present invention:

[0025] In the present invention, a double-layer coating structure is adopted to optimize the performance of azo pigments, enabling the organic pigments to have the advantages of dispersibility, light fastness, high coloring power, water and oil resistance, and acid and alkali resistance. The first hydrophilic coating focuses on optimizing dispersibility to ensure that the pigments do not agglomerate in aqueous media. The second hydrophobic coating focuses on functional protection (light fastness, water and oil resistance, and acid and alkali resistance) to extend the service life of the pigments. The double-layer structure enables the organic pigments to have excellent water dispersibility and hydrophobic protection at the same time, and this synergistic effect is difficult to achieve in single-layer coatings. The first hydrophilic coating is firmly bonded to the pigment surface, and the second hydrophobic coating is evenly attached through the active points provided by the hydrophilic layer, with high interlayer bonding strength and a more stable coating layer. In addition, the polar monomer acrylamide is introduced in the second hydrophobic coating to further improve the interfacial compatibility between the two layers and avoid delamination or peeling. The pigments with double-layer coating can not only meet the high dispersibility requirements of water-based inks, but also maintain good performance in complex environments without sacrificing the inherent color vitality of the organic pigments, and are applicable to a wider range of application scenarios. Description of the Drawings

[0026] The drawings are used to provide further explanation of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation to the present invention. In the drawings:

[0027] Figure 1 is a schematic cross-sectional view of the assembled dispersion stirring assembly disclosed in the present invention;

[0028] Figure 2 is a schematic three-dimensional view of the dispersion stirring assembly disclosed in the present invention;

[0029] Figure 3 is a schematic cross-sectional view of the main shaft disclosed in the present invention;

[0030] Figure 4 is a schematic view of the drive shaft disclosed in the present invention;

[0031] Figure 5 Schematic structural diagram of the dispersion stirring blade disclosed in the present invention;

[0032] Figure 6 Schematic structural diagram of the horizontal section of the dispersion stirring assembly at the position of the dispersion stirring blade disclosed in the present invention. Specific embodiments

[0033] The technical solution of the present invention will be further described in detail below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the following embodiments only.

[0034] Embodiment 1

[0035] A preparation method of a high-performance organic pigment for water-based printing ink, comprising the following steps:

[0036] S1. By weight, 100 parts of Pigment Red 170 are dispersed in 400 parts of deionized water, and 2 parts of sodium dodecyl sulfate are added to prepare an organic pigment dispersion;

[0037] S2. 3.75 parts of acrylic acid, 2.25 parts of methacrylic acid and 0.375 parts of ethylene glycol dimethacrylate are added to the organic pigment dispersion, stirred and emulsified evenly, and then 0.15 parts of potassium persulfate are added continuously. The reaction temperature is controlled at 65 °C and the reaction is carried out for 4 h;

[0038] S3. After the reaction is completed, it is cooled to room temperature, centrifuged to remove unreacted monomers, and the pigment particles are washed repeatedly with deionized water to obtain the first-layer coated organic pigment;

[0039] S4. 6 parts of methyl methacrylate, 2 parts of butyl acrylate, 2 parts of glycidyl acrylate and 1 part of acrylamide are mixed, and 2 parts of sodium dodecyl sulfate and 50 parts of deionized water are added to prepare a microemulsion;

[0040] S5. 100 parts of the first-layer coated organic pigment are dispersed in 400 parts of deionized water, the reaction temperature is controlled at 75 °C, the microemulsion and 0.25 parts of potassium persulfate are added dropwise, and the reaction is carried out for 4 h;

[0041] S6. After the reaction is completed, it is cooled to room temperature, centrifuged to remove unreacted monomers, and the pigment particles are washed repeatedly with deionized water and dried in vacuum to obtain the high-performance organic pigment for water-based printing ink.

[0042] Embodiment 2

[0043] A preparation method of a high-performance organic pigment for water-based printing ink, comprising the following steps:

[0044] S1. Disperse 100 parts by weight of Pigment Red 170 in 400 parts of deionized water, and add 2 parts of sodium dodecyl sulfate to prepare an organic pigment dispersion;

[0045] S2. Add 3 parts of acrylic acid, 3 parts of methacrylic acid and 0.3 part of ethylene glycol dimethacrylate to the organic pigment dispersion, stir and emulsify evenly, then continue to add 0.15 part of potassium persulfate, control the reaction temperature at 65 °C, and react for 4 h;

[0046] S3. After the reaction is completed, cool to room temperature, centrifuge to remove unreacted monomers, and repeatedly wash the pigment particles with deionized water to obtain the organically pigment with the first layer of coating;

[0047] S4. Mix 8 parts of methyl methacrylate, 2 parts of butyl acrylate, 3 parts of glycidyl acrylate and 1 part of acrylamide, add 2 parts of sodium dodecyl sulfate and 50 parts of deionized water to prepare a microemulsion;

[0048] S5. Disperse 100 parts of the organically pigment with the first layer of coating in 400 parts of deionized water, control the reaction temperature at 75 °C, dropwise add the microemulsion and 0.25 part of potassium persulfate, and react for 4 h;

[0049] S6. After the reaction is completed, cool to room temperature, centrifuge to remove unreacted monomers, repeatedly wash the pigment particles with deionized water, and dry in vacuum to obtain a high-performance organic pigment for water-based printing inks.

[0050] Comparative Example 1

[0051] A preparation method of an organic pigment, comprising the following steps:

[0052] S1. Disperse 100 parts by weight of Pigment Red 170 in 400 parts of deionized water, and add 2 parts of sodium dodecyl sulfate to prepare an organic pigment dispersion;

[0053] S2. Add 3.75 parts of acrylic acid, 2.25 parts of methacrylic acid and 0.375 part of ethylene glycol dimethacrylate to the organic pigment dispersion, stir and emulsify evenly, then continue to add 0.15 part of potassium persulfate, control the reaction temperature at 65 °C, and react for 4 h;

[0054] S3. After the reaction is completed, cool to room temperature, centrifuge to remove unreacted monomers, and repeatedly wash the pigment particles with deionized water to obtain an organically pigment coated with a hydrophilic polymer.

[0055] Comparative Example 2

[0056] A preparation method of an organic pigment, comprising the following steps:

[0057] S1. Disperse 100 parts by weight of Pigment Red 170 in 400 parts of deionized water, and add 2 parts of sodium dodecyl sulfate to prepare an organic pigment dispersion;

[0058] S2. Mix 6 parts of methyl methacrylate, 2 parts of butyl acrylate, 2 parts of glycidyl acrylate and 1 part of acrylamide, add 2 parts of sodium dodecyl sulfate and 50 parts of deionized water to prepare a microemulsion;

[0059] S3. Disperse 100 parts of the organic pigment in 400 parts of deionized water, control the reaction temperature at 75 °C, dropwise add the microemulsion and 0.25 parts of potassium persulfate, and react for 4 h;

[0060] S4. After the reaction is completed, cool to room temperature, centrifuge to remove unreacted monomers, repeatedly wash the pigment particles with deionized water, and vacuum dry to obtain a hydrophobic polymer-coated organic pigment.

[0061] Comparative Example 3

[0062] A method for preparing an organic pigment, comprising the following steps:

[0063] S1. Disperse 100 parts by weight of Pigment Red 170 in 400 parts of deionized water, and add 2 parts of sodium dodecyl sulfate to prepare an organic pigment dispersion;

[0064] S2. Mix 3.75 parts of acrylic acid, 2.25 parts of methacrylic acid, 6 parts of methyl methacrylate and 2 parts of butyl acrylate, add 2 parts of sodium dodecyl sulfate and 50 parts of deionized water to prepare a microemulsion;

[0065] S3. Disperse 100 parts of the first-layer coated organic pigment in 400 parts of deionized water, control the reaction temperature at 75 °C, dropwise add the microemulsion and 0.25 parts of potassium persulfate, and react for 4 h;

[0066] S4. After the reaction is completed, cool to room temperature, centrifuge to remove unreacted monomers, repeatedly wash the pigment particles with deionized water, and vacuum dry to obtain a single-layer polymer-coated organic pigment.

[0067] Comparative Example 4

[0068] A method for preparing an organic pigment, comprising the following steps:

[0069] S1. Disperse 100 parts by weight of Pigment Red 170 in 400 parts of deionized water, and add 2 parts of sodium dodecyl sulfate to prepare an organic pigment dispersion;

[0070] S2. Add 3.75 parts of acrylic acid and 2.25 parts of methacrylic acid to the organic pigment dispersion, stir, emulsify evenly, continue to add 0.15 part of potassium persulfate, control the reaction temperature at 65 °C, and react for 4 h;

[0071] S3. After the reaction is completed, cool to room temperature, centrifuge to remove unreacted monomers, and repeatedly wash the pigment particles with deionized water to obtain the first-layer coated organic pigment;

[0072] S4. Mix 6 parts of methyl methacrylate, 2 parts of butyl acrylate, 2 parts of glycidyl acrylate and 1 part of acrylamide, add 2 parts of sodium dodecyl sulfate and 50 parts of deionized water to prepare a microemulsion;

[0073] S5. Disperse 100 parts of the first-layer coated organic pigment in 400 parts of deionized water, control the reaction temperature at 75 °C, dropwise add the microemulsion and 0.25 part of potassium persulfate, and react for 4 h;

[0074] S6. After the reaction is completed, cool to room temperature, centrifuge to remove unreacted monomers, repeatedly wash the pigment particles with deionized water, and dry in vacuum to obtain the high-performance organic pigment for water-based printing ink.

[0075] Comparative Example 5

[0076] A preparation method of an organic pigment, comprising the following steps:

[0077] S1. Disperse 100 parts of Pigment Red 170 in 400 parts of deionized water by weight, and add 2 parts of sodium dodecyl sulfate to prepare an organic pigment dispersion;

[0078] S2. Add 3.75 parts of acrylic acid, 2.25 parts of methacrylic acid and 0.375 part of ethylene glycol dimethacrylate to the organic pigment dispersion, stir, emulsify evenly, continue to add 0.15 part of potassium persulfate, control the reaction temperature at 65 °C, and react for 4 h;

[0079] S3. After the reaction is completed, cool to room temperature, centrifuge to remove unreacted monomers, and repeatedly wash the pigment particles with deionized water to obtain the first-layer coated organic pigment;

[0080] S4. Mix 6 parts of methyl methacrylate and 2 parts of butyl acrylate, add 2 parts of sodium dodecyl sulfate and 50 parts of deionized water to prepare a microemulsion;

[0081] S5. Disperse 100 parts of the first-layer coated organic pigment in 400 parts of deionized water, control the reaction temperature at 75 °C, dropwise add the microemulsion and 0.25 part of potassium persulfate, and react for 4 h;

[0082] After the reaction is completed, cool to room temperature, centrifuge to remove unreacted monomers, wash the pigment particles repeatedly with deionized water, and dry under vacuum to obtain the double-layer polymer-coated organic pigment.

[0083] Test Example 1

[0084] Perform performance tests on the pigments prepared in Examples 1-2 and Comparative Examples 1-5:

[0085] (1) Weigh 0.1 g of the pigment and 1.0 g of titanium dioxide, draw 1 mL of ink oil with a syringe, and grind it three times on a flat grinder, 50 revolutions each time. Perform a scraping test on the ground ink, and use a colorimeter to measure the tinting strength. The tinting strength of Pigment Red 170 without polymer coating is 100%;

[0086] (2) Test the lightfastness of the pigment according to GB / T 1710-2008;

[0087] (3) Test the water resistance, oil resistance, acid resistance and alkali resistance of the pigment according to GB / T 5211.5-2008.

[0088] The test results are shown in Table 1.

[0089] Group Tinting strength / % Light fastness Water resistance Oil resistance Acid resistance Alkali resistance Example 1 128.4 7～8 5 5 5 5 Example 2 126.5 7～8 5 5 5 5 Comparative Example 1 109.1 5～6 3～4 4 3～4 3～4 Comparative Example 2 101.1 6 4 4～5 4 4 Comparative Example 3 116.3 6～7 4～5 4～5 4～5 4～5 Comparative Example 4 119.7 7 4 4～5 4～5 4～5 Comparative Example 5 121.5 6～7 4～5 4～5 4～5 4～5

[0090] As can be seen from the results in Table 1, the organic pigment examples prepared in the embodiments of the present invention have achieved a comprehensive improvement in tinting strength, lightfastness, water resistance, oil resistance, acid resistance and alkali resistance through a double-layer coating design, showing excellent comprehensive performance. In Comparative Example 1, a single-layer hydrophilic polymer coating was used, which had strong water absorption in the water environment, resulting in poor water resistance and lightfastness, and lacked hydrophobic protection, with limited tolerance to erosion in oily, acidic and alkaline environments. In Comparative Example 2, a single-layer hydrophobic polymer coating was used, and the dispersibility of the hydrophobic layer in water was not improved, the tinting strength did not increase significantly, and other performances were also average. In Comparative Example 3, a single-layer combined coating of hydrophilic and hydrophobic mixture was used, and compared with Comparative Examples 1 and 2 with single coatings, the dispersibility was also significantly increased, and the lightfastness, acid resistance and alkali resistance were all improved. In Comparative Example 4, ethylene glycol dimethacrylate was not added as a crosslinking monomer to the hydrophilic layer, and the compactness and stability of the coating layer on the surface of the organic pigment were slightly lacking. The double-layer coating structure design effectively improved the protection ability of the pigment and could block most of the acid-base erosion, but part of the structure was missing and the performance was slightly reduced. In Comparative Example 5, functional monomers were not added to the hydrophobic layer, and the interfacial bonding force with the hydrophilic layer was reduced, and the structural integrity of the coating on the surface of the organic pigment became worse, resulting in the performance of the prepared pigment being lower than that in the examples. The double-layer coating structure in the embodiments of the present invention provides a more comprehensive protection system through the synergistic effect of the polar protection of the hydrophilic layer and the non-polar protection of the hydrophobic layer. The hydrophilic layer and the hydrophobic layer respectively solve the stability problems in different environments, and at the same time, with the crosslinking of functional monomers and active groups, the compactness, bonding force and durability of the coating layer are significantly improved. This double-layer coating design shows obvious advantages in key performances such as tinting strength, lightfastness, water resistance, oil resistance, acid and alkali resistance, meeting the requirements of azo pigments in complex application environments such as water-based printing inks.

[0091] Test Example 2

[0092] Perform stability tests on the pigments prepared in Examples 1-2 and Comparative Examples 1-5:

[0093] (1) Storage stability: Disperse the pigments prepared in Examples 1-2 and Comparative Examples 1-5 in equal portions in deionized water, and store them statically at 60 °C for one week and at 45 °C for 30 days respectively, and observe whether precipitation occurs;

[0094] (2) Thermal cycling stability: Disperse the pigments prepared in Examples 1-2 and Comparative Examples 1-5 in equal portions in deionized water, store them statically at 70 °C for 4 hours and then at -20 °C for 4 hours, then store them statically at 70 °C for 4 hours and then place them at -20 °C for 4 hours, and cycle 4 times; Use a laser particle size analyzer to test the particle size change of the pigment particles before and after storage.

[0095] The test results are shown in Table 2.

[0096] Table 2

[0097]

[0098] As can be seen from the data in Table 2, the organic pigments prepared in Examples 1 and 2 have better storage stability, with less increase in particle size after thermal shock testing and better stability. For the organic pigment with a single-layer hydrophilic polymer in Comparative Example 1, in a high-temperature environment, the hydrophilic polymer will absorb water and swell, causing the coating layer to become loose and the particle size to increase; in a low-temperature environment, the hydrophilic polymer shrinks or loses elasticity, and the physical attraction between pigment particles increases, resulting in partial agglomeration. For the organic pigment with a single-layer lipophilic polymer in Comparative Example 2, it lacks affinity in an aqueous environment and has poor dispersibility. Temperature changes cause the accumulation of interfacial stress in the coating layer, and the hydrophobic layer may crack and peel off, reducing the stability of pigment particles. In Comparative Example 3, with a single-layer coating combining hydrophilic and hydrophobic layers, compared with Comparative Examples 1 and 2, its storage stability and thermal cycling stability are significantly improved, but the overall mechanical strength of the single-layer coating is weak, and partial peeling will still be caused by thermal cycling. In Comparative Example 4, no cross-linking monomer was added to the hydrophilic layer, resulting in insufficient mechanical strength and durability of the coating layer. It is prone to swelling or cracking in a high-temperature environment, and the shrinkage in a low-temperature environment will exacerbate the interfacial stress between the hydrophilic layer and the hydrophobic layer, leading to cracking of the coating layer. In Comparative Example 5, without a functional monomer, the binding force between the hydrophilic layer and the hydrophobic layer decreases, the coating structure is not stable enough, and it is also prone to cracking of the coating layer.

[0099] Example 3,

[0100] Before S1, deionized water is injected into container 1;

[0101] In S1, the organic pigment is dispersed in deionized water, including adding the organic pigment to deionized water and using a dispersion stirring assembly for dispersion;

[0102] In S2, after adding a hydrophilic monomer and a cross-linking monomer to the organic pigment dispersion, use a dispersion stirring assembly for stirring;

[0103] The dispersion stirring assembly is arranged above container 1. The dispersion stirring assembly includes a main shaft 2 and a plurality of dispersion stirring blades 3 spirally arranged on the outer circumferential surface of the main shaft 2. The dispersion stirring blades 3 are rotationally connected to the main shaft 1.

[0104] The main shaft 2 is a hollow shaft with an open upper end. A driving shaft 4 is slidably arranged inside the main shaft 2. A transmission wheel 5 is fixedly arranged on the part of the driving shaft 4 extending out of the main shaft 2. The transmission wheel 5 abuts against a conical driving wheel 6 arranged on the power output shaft of a power element 7.

[0105] When the driving shaft 4 moves axially relative to the main shaft 2, the rotational speed of the driving shaft 4 decreases, and the driving shaft 4 drives the dispersion stirring blades 3 to rotate.

[0106] Working principle of the above technical solution:

[0107] A fixed bracket 8 is arranged at the upper part of the container 1. A main shaft 2 is rotatably arranged on the fixed bracket 8. The axis of the main shaft 2 coincides with the vertical center line of the container 2. A number of dispersing and stirring blades 3 distributed in a spiral are rotatably arranged on the outer circumference of the part of the lower position of the main shaft 2 in the container 1. The main shaft 2 is a hollow shaft with an open upper end. A driving shaft 4 is slidably arranged in the main shaft 2. The driving shaft 4 can be set as a spline shaft. Key grooves corresponding to the spline shaft are formed on the inner wall of the main shaft 2. A transmission wheel 5 is fixedly arranged on the part of the driving shaft 4 extending out of the main shaft 2. The outer circumferential surface of the transmission wheel 5 abuts against the conical surface of the driving wheel 6, and power is transmitted to the driving shaft 4 through friction. The axis of the driving shaft 4 and the axis of rotation of the driving wheel 6 are in the same vertical plane. The included angle between the axis of rotation of the driving shaft 4 and the axis of rotation of the power output shaft of the power element 7 is equal to the included angle between the axis of rotation of the power output shaft of the power element 7 and the conical surface of the driving wheel 6. When the driving shaft 4 moves axially, the transmission wheel 5 is driven to move. When the circumferential surface of the transmission wheel 5 contacts different positions along the axis of the driving wheel 6, the rotation speed of the driving shaft 4 is different. As Figure 1 shown, when the rotation speed of the power output shaft of the power element 7 remains unchanged, during the upward movement of the transmission wheel 5, the rotation speed of the driving shaft 4 gradually decreases.

[0108] A spline 11 along the axial direction is fixedly arranged in the middle of the outer circumferential surface of the driving shaft 4. A spline groove 10 adapted to the spline 11 is formed in the upper part of the inner wall of the main shaft 2. The spline 12 is slidably arranged in the spline groove.

[0109] Through holes 9 arranged in a spiral are formed in the lower part of the side wall of the main shaft 2. The dispersing and stirring blades 3 are fan-shaped. One end of the dispersing and stirring blade 3 close to the center of the circle is fixedly connected to a rotating shaft 13. The rotating shaft 13 is rotatably arranged in the through hole 9. A sliding groove 14 is fixedly arranged at one end of the rotating shaft extending into the cavity of the main shaft. A sliding column 12 is fixedly arranged at the lower part of the outer circumference of the driving shaft 4 corresponding to the sliding groove 14. The sliding column 12 is slidably arranged in the sliding groove 14.

[0110] A number of grooves 15 are formed on the arc surface of the dispersing and stirring blade 3, which plays a better dispersing role.

[0111] When dispersing particulate materials in a liquid, the plane of the dispersing and stirring blade 3 is parallel to the rotating plane. The rotating speed of the dispersing and stirring blade 3 is relatively high, which can provide strong shear force and impact force, improving the dispersion efficiency of the materials. Since the plane of the dispersing and stirring blade 3 is parallel to the rotating plane, the agitation in the axial direction of the liquid is relatively small, and the liquid cannot be fully mixed, so it is not suitable for stirring. However, if the dispersion and stirring are completed by different devices respectively, the cost and production time will increase. When stirring, the angle of the dispersing and stirring blade 3 can be rotated. After rotation, the dispersing and stirring blade 3 forms a certain angle with the rotating plane, which can generate an axial push on the liquid and improve the stirring efficiency. After rotating a certain angle, the impact force received by the dispersing and stirring blade 3 will increase, and the strength requirement for the dispersing and stirring blade 3 also increases. Since strong shear force and impact force during the dispersion process are not required during stirring, reducing the rotating speed of the drive shaft during stirring can ensure that the dispersing and stirring blade 3 will not be damaged and can also ensure the mixing effect during the stirring process.

[0112] As Figure 1 - 6 shown, during the upward movement of the drive shaft 4, the rotational speed of the drive shaft 4 gradually decreases. The sliding column 12 on the drive shaft 4 drives the dispersing and stirring blade 3 to rotate through the sliding groove 14, so that when the dispersing and stirring assembly is in the dispersing working state, the plane of the dispersing and stirring blade 3 is parallel to the rotating plane, and the drive shaft 4 rotates at a high speed to meet the requirements of the dispersing working state. During the stirring state, the drive shaft 4 moves upward, the plane of the dispersing and stirring blade 3 forms a certain angle with the rotating plane, and the drive shaft 4 rotates at a lower speed.

[0113] Adopting the above technical solution, the dispersing and stirring assembly can be used to disperse particulate materials to form a dispersion liquid, and can also stir the dispersion liquid added with monomers to make the emulsification more uniform. The dispersing and stirring assembly has a simple structure, low cost, and improves the production efficiency.

[0114] Finally, it should be noted that the above embodiments only represent several implementation manners of the present invention and are not intended to limit the present invention. For those of ordinary skill in the art, any modifications, equivalent replacements, improvements, etc. made without departing from the concept of the present invention should be included within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be subject to the appended claims.

Claims

1. A preparation method of a high-performance organic pigment for water-based printing ink, characterized in that, It includes the following steps: S1. Disperse the organic pigment in deionized water, add an emulsifier, and prepare an organic pigment dispersion; S2. Add a hydrophilic monomer and a crosslinking monomer to the organic pigment dispersion, stir, emulsify evenly, continue to add an initiator, and control the reaction temperature and time to ensure complete polymerization of the monomers; S3. After the reaction is completed, cool to room temperature, centrifuge to remove unreacted monomers, and repeatedly wash the pigment particles with deionized water to obtain the organic pigment with the first layer of coating; S4. Mix the hydrophobic monomer and the functional monomer, add an emulsifier and deionized water, and prepare a microemulsion; S5. Disperse the organic pigment with the first layer of coating in deionized water, control the reaction temperature, dropwise add the microemulsion and the initiator, and control the reaction time to ensure complete polymerization of the monomers; S6. After the reaction is completed, cool to room temperature, centrifuge to remove unreacted monomers, repeatedly wash the pigment particles with deionized water, and dry them under vacuum to obtain the high-performance organic pigment for water-based printing ink; In step S2, the hydrophilic monomer is acrylic acid and methacrylic acid; the crosslinking monomer is ethylene glycol dimethacrylate; the mass ratio of acrylic acid, methacrylic acid and ethylene glycol dimethacrylate is (8-12):(5-8):1; In step S4, the hydrophobic monomer is methyl methacrylate and butyl acrylate; the functional monomer is glycidyl acrylate and acrylamide; the mass ratio of methyl methacrylate, butyl acrylate, glycidyl acrylate and acrylamide is (5-8):(1.5-3):(1-3):

1.

2. The preparation method of the high-performance organic pigment for water-based printing ink according to claim 1, characterized in that, The organic pigment is an azo pigment.

3. The preparation method of the high-performance organic pigment for aqueous printing ink according to claim 1, characterized in that, In steps S1 and S4, the emulsifier is sodium dodecyl sulfate; in steps S2 and S5, the initiator is potassium persulfate.

4. The preparation method of the high-performance organic pigment for water-based printing ink according to claim 1, wherein The mass ratio of the total amount of the organic pigment and the hydrophilic monomer is 100:(5-7).

5. The preparation method of the high-performance organic pigment for water-based printing ink according to claim 1, characterized in that, In step S2, the reaction temperature is 60-70°C, and the reaction time is 3-5 h.

6. The preparation method of the high-performance organic pigment for water-based printing ink according to claim 1, characterized in that, The mass ratio of the total amount of the organic pigment with the first layer of coating and the hydrophobic monomer is 100:(6-10).

7. The preparation method of the high-performance organic pigment for water-based printing ink according to claim 1, characterized in that, In step S5, the reaction temperature is 70-80°C, and the reaction time is 3-5 h.

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