A pre-dispersed pigment, its preparation method and application

Abstract

This invention belongs to the field of pigment dispersion technology, specifically relating to a pre-dispersed pigment, its preparation method, and its application. The invention provides a method for preparing a pre-dispersed pigment, comprising the following steps: sequentially stirring, mixing, and grinding a pigment, a polymeric wax, and stearic acid to obtain the pre-dispersed pigment; the polymeric wax has a molecular weight of 10,000 to 30,000, a melting point of 100 to 150°C, and a viscosity of 200 to 500 cps; the pigment has a particle size (D97) not exceeding 25 μm, an oil absorption of not more than 50%, and an electrical conductivity not exceeding 60 μS / cm. The method provided by this invention can reduce the wax content in the pre-dispersed pigment and further improve the dispersion effect of the pigment in subsequent applications.

Description

Technical Field

[0001] This invention belongs to the field of pigment dispersion technology, specifically relating to a pre-dispersed pigment, its preparation method, and its application. Background Technology

[0002] Regarding the pre-dispersion treatment of organic pigments (applied to masterbatches), the publicly disclosed technical routes to date are mainly: (1) water dewatering and phase inversion: first, the pigment with high water content is ground using a grinding device, and after reaching the set fineness, polymer wax is added, negative pressure is applied, and the temperature is raised to remove the water. The wax coats the surface of the pigment particles, resulting in a pre-dispersion pigment with a pigment content of about 50%; (2) using a kneader or internal mixer to heat and knead the mixture of pigment powder and wax simultaneously, resulting in a pre-dispersion pigment with a pigment content of about 50%; (3) using a three-roll mill to process the product of method (2) again and pulverize it. However, all three of these main traditional methods have the problem of excessively high wax content, which affects the compatibility with downstream resins. In particular, when coloring chemical fiber filaments, it will cause serious problems of filament breakage. Summary of the Invention

[0003] The purpose of this invention is to provide a pre-dispersed pigment, its preparation method, and its application. The method provided by this invention can reduce the wax content in the pre-dispersed pigment and further improve the dispersion effect of the pigment.

[0004] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing a pre-dispersed pigment, comprising the following steps: The pigment, polymer wax, and stearic acid are stirred, kneaded, and ground sequentially to obtain the pre-dispersed pigment; The polymer wax has a molecular weight of 10,000 to 30,000, a melting point of 100 to 150°C, and a viscosity of 200 to 500 cps. The pigment has a particle size (D97) not exceeding 25 μm, an oil absorption rate not exceeding 50%, and an electrical conductivity not exceeding 60 μS / cm.

[0005] Preferably, the mass ratio of the pigment to the polymer wax is 7~8:2~3; The mass ratio of the polymeric wax to stearic acid is 1~2:1~2; The stearic acid has a melting point of 55~70℃ and a viscosity of 10~15cps.

[0006] Preferably, the stirring includes performing a first stirring and a second stirring in sequence; The first stirring speed is 300~500 rpm, and the time is 3~5 min; The second stirring speed is 800~1000 rpm, and the time is 3~5 min.

[0007] Preferably, the total color difference of the mixture obtained after stirring does not exceed 0.8.

[0008] Preferably, the mixing conditions include: the temperature is set 5-10°C higher than the melting point of the polymer wax, and the time is 10-20 minutes.

[0009] Preferably, the process of mixing further includes cooling the resulting material to 80-100°C.

[0010] Preferably, the grinding conditions include: using a three-roll mill, setting the temperature to be 10°C or higher than the melting point of the polymer wax; the rotational speeds of the three rollers in the three-roll mill are 30 rpm, 90 rpm and 270 rpm respectively, the gap between the first roller and the second roller is 1~1.5 mm, and the gap between the second roller and the third roller is 0.05 mm.

[0011] Preferably, after grinding, the material is further cooled to room temperature and then crushed. The mass percentage of the material obtained after crushing is 70% of the material with a particle size of 1-2 mm.

[0012] The present invention also provides a pre-dispersed pigment prepared by the preparation method described in the above technical solution.

[0013] The present invention also provides the application of the pre-dispersed pigments described above in fibers or films.

[0014] This invention provides a method for preparing a pre-dispersed pigment, comprising the following steps: sequentially stirring, mixing, and grinding a pigment, a polymeric wax, and stearic acid to obtain the pre-dispersed pigment; the polymeric wax has a molecular weight of 10,000 to 30,000, a melting point of 100 to 150°C, and a viscosity of 200 to 500 cps; the pigment has a particle size (D97) not exceeding 25 μm, an oil absorption of not more than 50%, and an electrical conductivity not exceeding 60 μS / cm. This invention, through precise control of raw material parameters, effectively ensures pigment dispersibility even with low-content polymeric wax coating, while simultaneously improving compatibility with resins in downstream applications and preventing fiber breakage problems in subsequent applications. Attached Figure Description

[0015] Figure 1 The results of the pressure filtration value test for the pre-dispersed pigment obtained in Example 1; Figure 2 The results of the pressure filtration value test for the pre-dispersed pigment obtained in Example 2; Figure 3 The pressure filtration value test results are for the pre-dispersed pigment obtained in Example 3. Detailed Implementation

[0016] This invention provides a method for preparing a pre-dispersed pigment, comprising the following steps: The pigment, polymer wax, and stearic acid are stirred, kneaded, and ground sequentially to obtain the pre-dispersed pigment; The polymer wax has a molecular weight of 10,000 to 30,000, a melting point of 100 to 150°C, and a viscosity of 200 to 500 cps. The pigment has a particle size (D97) not exceeding 25 μm, an oil absorption rate not exceeding 50%, and an electrical conductivity not exceeding 60 μS / cm.

[0017] In this invention, the pigment particle size D97 does not exceed 25 μm, specifically 16 μm or 21 μm; the oil absorption does not exceed 50%, specifically 45% or 48%; and the electrical conductivity does not exceed 60 μS / cm, specifically 30 μS / cm, 36 μS / cm, or 45 μS / cm. By controlling the pigment parameters within the above ranges, on the one hand, controlling the particle size improves the pigment's dispersibility and prevents agglomeration during pre-dispersion; on the other hand, controlling the oil absorption reduces the amount of wax used for coating to some extent. Furthermore, controlling the pigment's electrical conductivity prevents problems such as high filtration pressure, filament breakage during spinning, and crystal points in blown film during subsequent applications.

[0018] In this invention, the chromaticity DE of the pigment is preferably ≤1.0, specifically 0.58, 0.65, or 0.4; the moisture content is preferably ≤1.0%; and the temperature resistance of the pigment is preferably not lower than 220°C.

[0019] This invention does not specifically limit the type of pigment; any pigment well-known to those skilled in the art can be used. In specific embodiments, the pigment may be Pigment Yellow 150, Pigment Blue 15:3, or Pigment Violet 23.

[0020] In this invention, the polymer wax has a molecular weight of 10,000 to 30,000, specifically 25,000; a melting point of 100 to 150°C, specifically 110°C, 120°C, 130°C, or 140°C; and a viscosity of 200 to 500 cps, specifically 210 cps, 220 cps, 230 cps, or 240 cps. By controlling the parameters of the polymer wax within the above ranges, this invention addresses two issues: firstly, a wax with a too-low melting point is prone to precipitation in the product, causing fiber breakage when used to make synthetic fibers; secondly, a too-high melting point hinders pigment dispersion, preventing the pigment aggregates from breaking down and also causing fiber breakage. Simultaneously, lower viscosity promotes pigment dispersion, but excessively low viscosity can cause compatibility issues with downstream plastic materials. By controlling these parameters, the dispersibility of the pigment can be effectively guaranteed even with low-content pigment coating, while preventing fiber breakage in subsequent applications.

[0021] In this invention, the stearic acid preferably has a melting point of 55-70°C, specifically 60°C, 65°C, 69.6°C, or 70°C, and a preferred viscosity of 10-15 cps, specifically 11 cps, 12 cps, 13 cps, or 14 cps. In this invention, low-viscosity stearic acid can penetrate into the micropores and capillaries of the pigment through a siphon effect, simultaneously acting as an isolation and coating agent. The polymer wax has a lubricating effect, responsible for wetting the exterior of the pigment. During application, it has good affinity with the matrix material, thus acting as a connector between the pigment and the matrix material. Its high viscosity facilitates the transmission of physical shear forces to the outside, helping to break up pigment aggregates.

[0022] In this invention, the preferred mass ratio of the pigment to the polymer wax is 7~8:2~3, specifically 7:2; the preferred mass ratio of the polymer wax to stearic acid is 1~2:1~2, specifically 2:1 or 1:1.

[0023] In this invention, the stirring is preferably carried out in a high-speed mixer; the stirring preferably includes performing a first stirring and a second stirring in sequence; the speed of the first stirring is preferably 300~500 rpm, and the time is preferably 3~5 min; the speed of the second stirring is preferably 800~1000 rpm, and the time is preferably 3~5 min.

[0024] In this invention, the total color difference of the mixture obtained by stirring is preferably no more than 0.8. In this invention, by controlling the total color difference of the mixture, it is confirmed that the mixture is uniformly mixed.

[0025] In this invention, the preferred conditions for the internal mixing process include: a temperature set 5-10°C higher than the melting point of the polymer wax, and a time of 10-20 minutes. Furthermore, the internal mixing process preferably includes cooling the resulting material to 80-100°C.

[0026] In this invention, the preferred grinding conditions include: using a three-roll mill, setting the temperature to be 10°C or higher than the melting point of the polymer wax; the rotational speeds of the three rollers in the three-roll mill are 30 rpm, 90 rpm and 270 rpm respectively, the gap between the first roller and the second roller is 1~1.5 mm, and the gap between the second roller and the third roller is 0.05 mm.

[0027] In this invention, after grinding, it is preferable to further crush the obtained pigment; the mass percentage of the material obtained after crushing is preferably 70% of the material with a particle size of 1 to 2 mm.

[0028] This invention also provides a pre-dispersed pigment prepared by the preparation method described in the above technical solution. In this invention, the pre-dispersed pigment has a filter pressure value (FPV) of less than 1.0 bar / g (tested with a 1400-mesh filter on 60g of pigment), and the pre-dispersed pigment does not exhibit color or wax migration to the surface of plastic products, does not discolor, and does not affect printing on the surface of the product; at the same time, melt-spun 1 denier filaments do not exhibit filament breakage.

[0029] The present invention also provides the application of the pre-dispersed pigments described above in fibers or films.

[0030] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.

[0031] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0032] Example 1 In this embodiment, the polymer wax has a molecular weight of 25,000, a melting point of 130°C, and a viscosity of 230 cps. Stearic acid has a melting point of 69.6℃ and a viscosity of 11 cps; The pigment is Pigment Yellow 150, with a color DE of 0.4, a moisture content of 0.8%, an electrical conductivity of 36 μS / cm, an oil absorption of 45%, and a particle size D97 of 23 μm. 50 kg of raw materials (pigment, polymer wax and stearic acid in a mass ratio of 7:2:1) were put into a high-speed mixer and stirred at 300 rpm for 5 minutes and then at 800 rpm for 5 minutes to obtain a sandy mixture. The total color difference DE of the mixture was tested to be 0.32. The obtained mixture was subjected to intensive mixing at a temperature of 140°C for 10 minutes. After intensive mixing, the temperature of the material was reduced to 80°C before grinding. Grinding was carried out using a three-roll mill at a temperature of 145°C. The rotation speeds of the three rollers in the three-roll mill were 30 rpm, 90 rpm, and 270 rpm, respectively. The gap between the first and second rollers was 1.5 mm, and the gap between the second and third rollers was 0.05 mm. After cooling to room temperature, the mixture was crushed, and the mass percentage of the material with a particle size of 1-2 mm was 70%, resulting in a pre-dispersed pigment.

[0033] Comparative Example 1 Another pigment, Yellow 150 (70% oil absorption, 160 μS / cm conductivity), was obtained as a pre-dispersed pigment according to Example 1.

[0034] Performance testing The pressure filtration values ​​of the pre-dispersed pigments obtained in Example 1 and Comparative Example 1 were tested; the pre-dispersed pigments and PE resin (melt index of 20~35 g / 10 min) were mixed at a mass ratio of 1:1 and granulated to obtain the test samples; The pressure filtration value test results of the pre-dispersed pigment obtained in Example 1 are as follows: Figure 1 As shown, the pre-dispersed pigment obtained by the method provided by the present invention has a pressure filtration value of 0.164 bar / g, which fully meets the application requirements of chemical fiber (the industry standard for spinning masterbatch requires a pressure filtration value FPV of less than 1.0 bar / g, and a 60g sample is tested using a 1400-mesh filter); while the pre-dispersed pigment obtained in Comparative Example 1 has a pressure filtration value of 3.4 bar / g.

[0035] The color performance of the pre-dispersed pigment in Example 1 was compared with that of the untreated pigment in Example 1. The results of the computer colorimeter showed that the color power of the pre-dispersed pigment was improved by 25.4%.

[0036] Example 2 In the examples, the polymer wax has a molecular weight of 25,000, a melting point of 130°C, and a viscosity of 230 cps; Stearic acid has a melting point of 69.6℃ and a viscosity of 11 cps; The pigment is Pigment Blue 15:3, the color DE is 0.65, the water content is 0.7%, the electrical conductivity is 30μS / cm, the oil absorption is 48%, and the particle size D97 is 16μm. 50 kg of raw materials (pigment, polymer wax and stearic acid in a mass ratio of 7:2:1) were put into a high-speed mixer and stirred at 300 rpm for 5 minutes and then at 800 rpm for 5 minutes to obtain a sandy mixture. The total color difference DE of the mixture was tested to be 0.45. The obtained mixture was subjected to intensive mixing at a temperature of 140°C for 10 minutes. After intensive mixing, the temperature of the material was reduced to 80°C before grinding. Grinding was carried out using a three-roll mill at a temperature of 145°C. The rotation speeds of the three rollers in the three-roll mill were 30 rpm, 90 rpm, and 270 rpm, respectively. The gap between the first and second rollers was 1.5 mm, and the gap between the second and third rollers was 0.05 mm. After cooling to room temperature, the mixture was crushed, and the mass percentage of the material with a particle size of 1-2 mm was 70%, resulting in a pre-dispersed pigment.

[0037] Comparative Example 2 Another pigment blue 15:3 (oil absorption 82%, electrical conductivity 100 μS / cm); a pre-dispersed pigment was obtained according to the method of Example 2.

[0038] The pressure filtration value was tested according to the above test procedure. The pressure filtration value test results of the pre-dispersed pigment obtained in Example 2 are as follows: Figure 2 As shown, the pre-dispersed pigment obtained by the method provided by the present invention has a filter pressure value of 0.001 bar / g, which fully meets the application requirements of chemical fiber (the industry standard for spinning masterbatch requires a filter pressure value FPV of less than 1.0 bar / g); while the pre-dispersed pigment obtained in Comparative Example 2 has a filter pressure value of 2.9 bar / g. The color performance of the pre-dispersed pigment in Example 2 was compared with that of the untreated pigment in Example 2. The results of the computer colorimeter showed that the color power of the pre-dispersed pigment was improved by 13.3%.

[0039] Example 3 In the examples, the polymer wax has a molecular weight of 25,000, a melting point of 130°C, and a viscosity of 230 cps; Stearic acid has a melting point of 69.6℃ and a viscosity of 11 cps; The pigment is Pigment Violet 23, with a chromaticity DE of 0.58, a moisture content of 0.8%, an electrical conductivity of 45 μS / cm, an oil absorption of 48%, and a particle size D97 of 21 μm. 50 kg of raw materials (pigment, polymer wax and stearic acid in a mass ratio of 7:2:1) were put into a high-speed mixer and stirred at 360 rpm for 5 minutes and then at 800 rpm for 5 minutes to obtain a mixture. The total color difference DE of the mixture was tested to be 0.25. The obtained mixture was subjected to intensive mixing at a temperature of 138°C for 10 minutes. After intensive mixing, the material temperature was reduced to 80°C before grinding. Grinding was performed using a three-roll mill at a temperature of 140°C. The rotation speeds of the three rollers in the three-roll mill were 30 rpm, 90 rpm, and 270 rpm, respectively. The gap between the first and second rollers was 1.5 mm, and the gap between the second and third rollers was 0.05 mm. After cooling to room temperature, the mixture was crushed, with the mass percentage of material having a particle size of 1-2 mm being 70%. After cooling to room temperature, the mixture was crushed again to obtain a pre-dispersed pigment.

[0040] Comparative Example 3 Another pigment, Violet 23 (80% oil absorption, 125 μS / cm conductivity), was obtained as a pre-dispersed pigment according to Example 3.

[0041] The pressure filtration value was tested according to the above test procedure. The pressure filtration value test results of the pre-dispersed pigment obtained in Example 3 are as follows: Figure 3 As shown, the pre-dispersed pigment obtained by the method provided by the present invention has a filter pressure value of 0.164 bar / g, which fully meets the application requirements of chemical fiber (the industry standard for spinning masterbatch requires a filter pressure value FPV of less than 1.0 bar / g); while the pre-dispersed pigment obtained in Comparative Example 3 has a filter pressure value of 3.5 bar / g. The color performance of the pre-dispersed pigment in Example 3 was compared with that of the untreated pigment in Example 3. The results of the computer colorimeter showed that the color power of the pre-dispersed pigment was improved by 23%.

[0042] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing a pre-dispersed pigment, characterized in that, Includes the following steps: The pigment, polymer wax, and stearic acid are stirred, kneaded, and ground sequentially to obtain the pre-dispersed pigment; The polymer wax has a molecular weight of 10,000 to 30,000, a melting point of 100 to 150°C, and a viscosity of 200 to 500 cps. The pigment has a particle size (D97) not exceeding 25 μm, an oil absorption rate not exceeding 50%, and an electrical conductivity not exceeding 60 μS / cm.

2. The preparation method according to claim 1, characterized in that, The mass ratio of the pigment to the polymer wax is 7~8:2~3; The mass ratio of the polymeric wax to stearic acid is 1~2:1~2; The stearic acid has a melting point of 55~70℃ and a viscosity of 10~15cps.

3. The preparation method according to claim 1, characterized in that, The stirring includes performing a first stirring and a second stirring in sequence; The first stirring speed is 300~500 rpm, and the time is 3~5 min; The second stirring speed is 800~1000 rpm, and the time is 3~5 min.

4. The preparation method according to claim 1, characterized in that, The total color difference of the mixture obtained after stirring shall not exceed 0.

8.

5. The preparation method according to claim 1, characterized in that, The mixing conditions include: the temperature is set 5-10°C higher than the melting point of the polymer wax, and the time is 10-20 minutes.

6. The preparation method according to claim 5, characterized in that, The process of mixing also includes cooling the resulting material to 80-100°C.

7. The preparation method according to claim 1, characterized in that, The grinding conditions include: using a three-roll mill, with the temperature set to be 10°C or higher than the melting point of the polymer wax; the rotational speeds of the three rollers in the three-roll mill are 30 rpm, 90 rpm and 270 rpm respectively, the gap between the first roller and the second roller is 1~1.5 mm, and the gap between the second roller and the third roller is 0.05 mm.

8. The preparation method according to claim 1, characterized in that, The grinding process further includes cooling the resulting material to room temperature before crushing it. The mass percentage of the material obtained after crushing is 70% of the material with a particle size of 1-2 mm.

9. The predispersed pigment prepared by the preparation method according to any one of claims 1 to 8.

10. The use of the predispersed pigment of claim 9 in fibers or films.

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