Polyurethane dispersant having a branched structure, method of preparation and aqueous colorant

Abstract

The application discloses a polyurethane dispersant with a branched structure, a preparation method and a water-based colorant. The preparation method of the polyurethane dispersant comprises the following steps: (1) reacting an isocyanate compound with a polyol to obtain a polyurethane prepolymer; (2) reacting the polyurethane prepolymer with a crosslinking agent to obtain a polyurethane compound with a branched structure; (3) dissolving a dye containing an active group in an organic solvent, and then adding the polyurethane compound with the branched structure to react; and (4) after the reaction is completed, the temperature is reduced to room temperature, and vacuum distillation is carried out to obtain the polyurethane dispersant with the branched structure. The polyurethane dispersant can reduce the viscosity of a system, can improve the content of coloring substances in a colorant system, can prepare a water-based colorant with a high content, and can be applied to fabric dyeing and building paint coloring. The prepared water-based colorant has the advantages of low viscosity and fineness, strong coloring power, good storage stability and the like.

Description

Technical Field

[0001] This invention relates to the field of colorant technology, and particularly to a polyurethane dispersant with a branched structure, its preparation method, and an aqueous colorant containing the polyurethane dispersant. Background Technology

[0002] Waterborne colorants, formed by stably dispersing dyes / pigments in an aqueous system, are an effective solution to avoid solid particle dust pollution and improve tinting strength, brightness, and other performance characteristics. Dispersants are key additives that ensure the stable dispersion of dye / pigment particles in an aqueous system, significantly influencing the tinting strength and compatibility with the substrate. Dispersants not only need to be well anchored to the surface of dye / pigment particles but also need to provide strong steric hindrance and electrostatic repulsion between the well-dispersed dye / pigment particles in the aqueous dispersion to prevent aggregation. Therefore, high requirements are placed on the dispersant's structure, molecular weight, hydrophilicity, and the distribution of anchoring groups.

[0003] In the coatings industry, coatings can be classified into various types based on the film-forming substance, such as polyurethane, epoxy resin, and acrylic. Colored coatings are typically produced by adding different proportions of pigment dispersions to white paint or varnish, followed by mixing and stirring. For example, Chinese patent CN107793845A discloses a water-based color paste for architectural coatings, composed of a pH adjuster, thickener, pigment, and polymeric dispersant. The polymeric dispersant is a water-soluble polymeric dispersant; in the examples, a polyester-type polymeric dispersant is used. Chinese patent CN103031023 discloses a method for preparing a high-performance, cost-effective water-based iron oxide black color paste, wherein the dispersant is a maleic anhydride-styrene polymer with anionic / nonionic characteristics, containing ammonium salt pigment affinity groups and hydrophilic groups, preferably a maleic anhydride-styrene-amine salt copolymer solution.

[0004] In the textile industry, polyester fabrics are the most widely produced and used synthetic fiber fabrics due to their high resilience, abrasion resistance, stability, and wrinkle resistance. They are widely used in clothing, home textiles, decoration, and industrial applications. Because polyester molecular chains lack specific dyeing groups and have low polarity, dyeing is relatively difficult, and dyeability is poor, making it hard for dye molecules to penetrate the fiber. Hot melt dyeing is one of the commonly used dyeing methods for polyester fabrics. Under high temperature conditions, the molecular chain segments of polyester fibers move violently, increasing the instantaneous gaps between molecular chains, allowing disperse dyes to diffuse into the interior, thus achieving the purpose of dyeing. Chinese patent CN105672002A discloses a method for continuous hot melt dyeing of polyester: when immersing polyester fabric in a dyeing solution, it undergoes two dips and two pads, followed by baking, washing, and finally drying. This improves the high fixation rate of disperse dyes on the fiber, reduces the burden of removing surface floating dyes after hot melt dyeing, and eliminates the need for reduction washing or soaping. Chinese patent CN111662405A applies polymer / disperse dye composite particles to the hot melt dyeing process of polyester, improving the dyeing efficiency and effect of disperse dyes. Hot melt dyeing has advantages such as simple process, continuous production, high production efficiency, low water consumption, and low wastewater. However, due to the high tension on the fabric during dyeing, the hand feel and color vibrancy of the dyed fabric are not ideal. Therefore, compared to other fields, polyester fabrics have higher requirements for the color fastness of the dyes used.

[0005] Polyurethane is widely used in the textile industry as a finishing agent, effectively improving the color depth, abrasion resistance, and dry cleaning properties of fabrics. It can be used for various purposes such as color fixing agents and adhesives. Chinese Patent CN104262570A discloses a method for preparing a black waterborne polyurethane dye by combining a black diol with a small molecule diol to partially or completely replace the small molecule diol, and then reacting it with diisocyanate, a macromolecular diol, and a hydrophilic chain extender. In this method, the black chromophore is chemically incorporated into the dye's molecular chain, fully utilizing the high-temperature resistance, solvent resistance, and migration resistance of the polymer dye. This technology has been applied in the field of synthetic leather dyes, demonstrating good dye durability, high color fastness, and good safety. In addition, Chinese Patent CN110483722A discloses a method for synthesizing a water-oil dual-purpose polyurethane dispersant for synthetic leather using a stepwise condensation method. The viscosity of the dispersant is improved by adjusting the ratio between the raw materials polyethylene glycol ether and diol ether. It is evident that polyurethane is already widely used in synthetic leather, but its application in polyester fabrics still has room for development.

[0006] Waterborne polyurethane dispersants are binary colloidal systems with water as the dispersed phase. They have low volatility, avoid pollution during use, and are beneficial to human health. They possess advantages such as being non-toxic, safe, environmentally friendly, having good film-forming properties, and being abrasion-resistant. Furthermore, polyurethane dispersants have attracted widespread attention due to their excellent dispersing performance and stability. Chinese patent CN111320738A discloses a polyurethane dispersant obtained by directly polymerizing a mixture of polydiol monomers, hydrophilic chain extenders, catalysts, organic solvents, and diisocyanate monomers. This polyurethane dispersant exhibits good dispersibility and strong adsorption of organic pigments. Chinese patent CN108373530A discloses a water-oil universal polyurethane dispersant. This dispersant is prepared by catalyzing the isocyanate reaction to obtain isocyanate polymers, then reacting polyether polyols and isocyanates to extend their chains, and further reacting with the resulting isocyanate polymers. It features good compatibility, good color development, good flexibility, and wide versatility.

[0007] Whether to use organic solvents in the preparation of polyurethane dispersants has always been a controversial topic. Chinese patent application CN107417873A proposes a method to react polyisocyanates with small-molecule hydrophilic chain extenders without the use of organic solvents to obtain polyurethane prepolymers with NCO-terminated ends. However, the viscosity of the polyurethane prepolymer is as high as 125,000 mPa·s. Excessive viscosity places high demands on the shear stress of subsequent manufacturing equipment and may even require modifications, resulting in high production costs and energy consumption. Japanese patent JP2006022133A explicitly states that when using polyisocyanates such as TDI and IPDI, their cyclic structure and low molecular skeleton flexibility lead to increased viscosity, thus necessitating the use of organic solvents to achieve better dispersion. European patent EP3253812A1 proposes that isocyanate-terminated polyurethane prepolymers, when mixed with pyrrolidone compounds, improve the coalescence phenomenon of polyurethane dispersion films. As mentioned above, although efforts are being made to develop waterborne polyurethane dispersions that are essentially solvent-free, controlling the viscosity of the prepolymer remains the primary objective, and the advantages of prepolymer mixing processes carried out in organic solvents are still significant.

[0008] In a superdispersant system, the superdispersant is tightly adsorbed onto the particle surface by its anchoring segment, while the solvation segment extends into the dispersion medium. When two particles adsorbed with superdispersant molecules approach each other, the particles are pushed apart due to the spatial obstruction of the extended chains, thus preventing flocculation and maintaining a stable dispersion state. German Patent No. DE102007049587A1 discloses a method for preparing a highly branched polyurethane dispersant through the reaction of highly branched polyurethane with polyether. Its branched structure achieves effective dispersion of solids and positively influences the viscosity and rheological properties of formulations containing solids. Summary of the Invention

[0009] To address the aforementioned technical problems, the present invention aims to provide a polyurethane dispersant with a branched structure, its preparation method, and an aqueous colorant containing the polyurethane dispersant. This polyurethane dispersant can reduce system viscosity, increase the content of coloring substances in the colorant system, and produce a high-concentration aqueous colorant. It can be applied to fabric dyeing and architectural coating coloring. The resulting aqueous colorant has advantages such as low viscosity and fineness, strong coloring power, and good storage stability.

[0010] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution:

[0011] A method for preparing a polyurethane dispersant with a branched structure includes the following steps:

[0012] (1) The isocyanate compound and the polyol are reacted at a temperature of 50-75°C for 3-5 hours to obtain a polyurethane prepolymer; a certain amount of organic solvent may also be added to reduce the viscosity of the system.

[0013] (2) The polyurethane prepolymer obtained in step (1) is reacted with a crosslinking agent for 3 to 5 hours to obtain a polyurethane compound with a branched structure.

[0014] (3) Dissolve the dye containing active groups in an organic solvent, then add the polyurethane compound with branched structure obtained in step (2), and react at a temperature of 50-80°C for 4-8 hours.

[0015] (4) After the reaction is complete, the temperature is lowered to room temperature and the mixture is distilled under reduced pressure to obtain a polyurethane dispersant with a branched structure.

[0016] The branched polyurethane dispersant prepared by this method has a molecular weight of 10,000 to 20,000 Daltons.

[0017] Preferably, the isocyanate compound is selected from at least one of isoflurane diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, dicyclohexylmethane diisocyanate, benzene diisocyanate, 1,5-naphthalene diisocyanate, and terephthalic diisocyanate.

[0018] Preferably, the polyol is polyethylene glycol with a molecular weight of 400 to 1000 Daltons, and can be selected from one or a mixture of two or more of PEG400, PEG600, and PEG1000.

[0019] Preferably, the crosslinking agent is selected from at least one of trimethylolpropane, triethanolamine, glycerol, and diethylenetriamine.

[0020] Preferably, the active group in the dye containing the active group is selected from at least one of hydroxyl and amino groups.

[0021] The dye containing the active group is further preferably Disperse Violet 26 or a dye having the structure shown in general formula (I);

[0022]

[0023] Wherein, R1 is H or OCH3, and R2 is H or NHCOCH3.

[0024] Preferably, the organic solvent in steps (1) and (3) is at least one of acetone, butanone, dioxane, N-methylpyrrolidone, ethyl acetate, and 2-ethoxyethyl acetate. Furthermore, the organic solvent used in step (3) is the same as the organic solvent in step (1). Specifically, the molar amount of the organic solvent in step (1) is 8 to 14 times the molar amount of the isocyanate compound; and the molar amount of the organic solvent in step (3) is 40 to 80 times the molar amount of the dye containing the active group.

[0025] Furthermore, the molar ratio of the isocyanate group of the isocyanate compound, the hydroxyl group of the polyol, the hydroxyl group of the crosslinking agent, and the active group of the dye is (10-20):(3-10):(3-8):1.

[0026] To increase the reaction rate, a certain amount of catalyst can be added before or during the reaction. The catalyst used is a tin-based or amine-based catalyst, such as dibutyltin dilaurate, triethylamine, N,N-dimethylpyridine-dimethylbenzylamine, N,N-dimethylaniline, N,N-dimethylpyridine, etc.

[0027] The present invention further provides a polyurethane dispersant with a branched structure, which is prepared by the above-described preparation method.

[0028] The present invention further provides an aqueous colorant comprising a coloring substance and the polyurethane dispersant described above. More specifically, the aqueous colorant comprises, by weight percentage, 38.0% to 50.0% of the coloring substance, 5.5% to 7.5% of the branched polyurethane dispersant, and 42.5% to 56.5% of water. The coloring substance is preferably a disperse dye or pigment.

[0029] The preparation method of this water-based colorant is as follows: the coloring substance, a polyurethane dispersant with a branched structure, and water are mixed, dispersed, ground, and filtered to obtain the water-based colorant. Specifically, zirconium beads with a diameter of 0.6–0.8 mm are added before grinding, and the mass of the zirconium beads is 2–3 times the total mass of the water-based colorant; the grinding speed is 3000–4000 r / min, and the grinding time is 1–3 h.

[0030] Furthermore, the coloring substances (dyes / pigments) in water-based colorants should be similar in color to the actual synthesized branched polyurethane dispersants to prevent color changes.

[0031] The present invention further provides the application of this water-based colorant in fabric dyeing and architectural coating coloring.

[0032] The beneficial effects of this invention are:

[0033] The branched polyurethane dispersant of this invention has numerous branching points, making its molecular chains less prone to entanglement, and possesses abundant terminal functional groups, which can serve as anchoring groups for coloring substances. More specifically, the introduced dye structure is similar to the structure of the coloring substance in the water-based colorant to be formed, which can improve the compatibility between the polyurethane dispersant and the coloring substance, and can form an inducing agent, giving the polyurethane dispersant groups that can anchor the coloring substance. During the preparation of the water-based colorant, the coloring substance (dye / pigment) can form "multi-point anchoring" with the dispersant containing multiple anchoring groups on the particle surface through dipole forces, which can both stabilize the dispersion of the dye / pigment and give each dye / pigment particle adhesive force. At the same time, by utilizing the high degree of crosslinking of this polyurethane dispersant, the adhesion of the polyurethane film to the surface floating color can be improved, thereby improving color fastness.

[0034] This invention utilizes isocyanate-containing compounds, crosslinking agents, polyols, and dyes containing active groups to prepare a branched polyurethane dispersant through a chemical reaction. This dispersant incorporates chromophores from the dye into the polyurethane molecular chain, resulting in a colored dispersant. By leveraging the significant viscosity reduction characteristic of this polyurethane dispersant, the solid content of the colorant dispersion can be increased, making it easier to prepare high-concentration colorant dispersions for application.

[0035] This invention introduces dyes with active groups into the polyurethane molecular chain, which not only improves the compatibility of polyurethane dispersants with coloring substances in water-based colorants and enhances the dispersibility of coloring substances, but also has a wide range of applications and can be used to prepare various water-based colorants.

[0036] Aqueous colorants prepared using this polyurethane dispersant are applied to fabric dyeing, resulting in dyed fabrics with low L-values, excellent rubbing resistance, and good color fastness to washing. Aqueous colorants prepared using this polyurethane dispersant are also applied to architectural coatings, exhibiting good compatibility with the system and advantages such as low viscosity and fineness, strong tinting strength, and good storage stability. Attached Figure Description

[0037] Figure 1 The infrared spectrum of the polyurethane dispersant with a branched structure prepared in Example 1 of this invention.

[0038] Figure 2The UV-Vis absorption spectra of Disperse Violet 26 and the branched polyurethane dispersant in Example 1 of this invention are shown. Detailed Implementation

[0039] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] This invention provides a method for preparing a polyurethane dispersant with a branched structure, comprising the following steps:

[0041] (1) The isocyanate compound and the polyol are reacted at a temperature of 50-75°C for 3-5 hours to obtain a polyurethane prepolymer; a certain amount of organic solvent may also be added to reduce the viscosity of the system.

[0042] (2) Add a certain amount of crosslinking agent to the polyurethane prepolymer obtained in step (1) and continue the reaction for 3 to 5 hours to obtain a polyurethane compound with a branched structure.

[0043] (3) Dissolve the dye containing active groups in an organic solvent, then add the polyurethane compound with branched structure obtained in step (2), and react at a temperature of 50-80°C for 4-8 hours.

[0044] (4) After the reaction is complete, the temperature is lowered to room temperature and the mixture is distilled under reduced pressure to obtain a polyurethane dispersant with a branched structure.

[0045] The branched polyurethane dispersant prepared by this method has a molecular weight of 10,000 to 20,000 Daltons.

[0046] The isocyanate compound is selected from at least one of isoflurane diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, dicyclohexylmethane diisocyanate, benzene diisocyanate, 1,5-naphthalene diisocyanate, and terephthalic diisocyanate.

[0047] The polyol is polyethylene glycol with a molecular weight of 400 to 1000 Daltons, and can be selected from one or a mixture of two or more of PEG400, PEG600 and PEG1000.

[0048] The crosslinking agent is selected from at least one of trimethylolpropane, triethanolamine, glycerol, and diethylenetriamine.

[0049] Among them, the active group in the dye containing the active group is selected from at least one of hydroxyl and amino groups.

[0050] The dye containing the active group is further preferably Disperse Violet 26 or a dye having the structure shown in general formula (I);

[0051]

[0052] Wherein, R1 is H or OCH3, and R2 is H or NHCOCH3.

[0053] The organic solvents used in steps (1) and (3) are at least one of acetone, butanone, dioxane, N-methylpyrrolidone, ethyl acetate, and 2-ethoxyethyl acetate. Furthermore, the organic solvent used in step (3) is the same as that used in step (1). Specifically, the molar amount of the organic solvent in step (1) is 8 to 14 times the molar amount of the isocyanate compound; and the molar amount of the organic solvent in step (3) is 40 to 80 times the molar amount of the dye containing the active group.

[0054] The molar ratio of the isocyanate group of the isocyanate compound, the hydroxyl group of the polyol, the hydroxyl group of the crosslinking agent, and the active group of the dye is (10-20):(3-10):(3-8):1.

[0055] To increase the reaction rate, a certain amount of catalyst can be added before or during the reaction. The catalyst used is a tin-based or amine-based catalyst, such as dibutyltin dilaurate, triethylamine, N,N-dimethylbenzylamine, N,N-dimethylaniline, N,N-dimethylpyridine, etc.

[0056] The present invention further provides a polyurethane dispersant with a branched structure, which is prepared by the above-described preparation method.

[0057] The present invention further provides an aqueous colorant comprising a coloring substance and the polyurethane dispersant described above. More specifically, the aqueous colorant comprises, by weight percentage, 38.0% to 50.0% of the coloring substance, 5.5% to 7.5% of the branched polyurethane dispersant, and 42.5% to 56.5% of water. The coloring substance is preferably a disperse dye or pigment.

[0058] The preparation method of this water-based colorant is as follows: the coloring substance, a polyurethane dispersant with a branched structure, and water are mixed, dispersed, ground, and filtered to obtain the water-based colorant. Specifically, zirconium beads with a diameter of 0.6–0.8 mm are added before grinding, and the mass of the zirconium beads is 2–3 times the total mass of the water-based colorant; the grinding speed is 3000–4000 r / min, and the grinding time is 1–3 h.

[0059] The coloring substances (dyes / pigments) in water-based colorants should be selected to be similar in color to the actual synthesized polyurethane dispersants with branched structures to prevent color changes.

[0060] This water-based colorant can be used in fabric dyeing (especially polyester fabric dyeing) and in architectural coating coloring.

[0061] The present invention will be further described below through specific embodiments.

[0062] In Examples 2 and 3 below, dye A and dye B have the structure shown in the general formula (Ⅰ) above; dye A: R1=H, R2=H; dye B: R1=OCH3, R2=NHCOCH3.

[0063] Both dye A and dye B were prepared by coupling N,N-dihydroxyethylaniline with aniline diazonium salts, as mentioned in Wang Yunming's article (Synthesis and Performance Study of Photothermal Conversion Polyether-based Shaped Phase Change Energy Storage Materials [D]. Dalian University of Technology, 2013).

[0064] Preparation of polyurethane dispersants

[0065] Example 1

[0066] 0.018 mol of isoflurane diisocyanate (IPDI), 0.2 mol of acetone, and 0.025 mL of dibutyltin dilaurate were added to a three-necked flask equipped with a condenser and an electric stirrer. 0.009 mol of PEG600 was then added to the flask, and the mixture was heated to 50 °C and reacted for 4 h. Then, 0.004 mol of trimethylolpropane (TMP) was added as a branching unit for a branching reaction for 4 h. 0.0012 mol of dispersible violet 26 was dispersed in 0.05 mol of acetone and added to the three-necked flask. The mixture was reacted at 50 °C for 6 h. After the reaction was complete, the mixture was cooled to room temperature, and the acetone was distilled off under reduced pressure to obtain a polyurethane dispersant A with a branched structure and a molecular weight of 15327 Daltons, anchored by a dye.

[0067] Figure 1 The infrared spectrum of the branched polyurethane dispersant prepared in Example 1; Figure 1 No aromatic primary amines were found at 3460 cm⁻¹ -1 and 3290cm -1 The characteristic absorption peaks nearby indicate that -NH2 has participated in the reaction.

[0068] Figure 2The UV-Vis absorption spectra of Disperse Violet 26 (V26) and the branched polyurethane dispersant in Example 1 are shown. Comparing the spectra of Disperse Violet 26 and the branched polyurethane dispersant reveals that the auxochrome group -NH2 attached to the anthraquinone group in the original low-molecular-weight Disperse Violet 26 dye reacts with NCO to form urethane or urea. On one hand, the carbonyl group of the urethane or urea is connected to oxygen and nitrogen atoms, exhibiting an electron-withdrawing inductive effect, thereby reducing the mobility of π in the entire anthraquinone ring. The energy level of the π* orbital increases relatively, requiring more energy to achieve n→π* and π→π* electronic transitions. On the other hand, after the dye reacts with the polyurethane, the intramolecular hydrogen bond formed between the NH2 at the α-position of the original dye chromophore and the C=O in the anthraquinone structure disappears. Therefore, the maximum absorption wavelength of the dye with the branched polyurethane group shifts to shorter wavelengths, resulting in a slightly lighter color.

[0069] Example 2

[0070] 0.018 mol of isoflurane diisocyanate (IPDI), 0.16 mol of butanone, and 0.025 mL of dibutyltin dilaurate were added to a three-necked flask equipped with a condenser and an electric stirrer. 0.009 mol of PEG600 was also added to the flask. The mixture was heated to 70 °C and reacted for 3 h. 0.004 mol of trimethylolpropane (TMP) was added as a branching unit for a branching reaction for 4 h. 0.0012 mol of dye A was dispersed in 0.08 mol of butanone and then added to the three-necked flask. The mixture was reacted at 75 °C for 5 h. After the reaction was complete, the mixture was cooled to room temperature, and the butanone was distilled off under reduced pressure to obtain a polyurethane dispersant B with a branched structure anchored by the dye, with a molecular weight of 17049 Daltons.

[0071] Example 3

[0072] 0.018 mol of isoflurane diisocyanate (IPDI) and 0.2 mol of acetone were added to a three-necked flask equipped with a condenser and an electric stirrer. 0.009 mol of PEG600 was also added to the flask, and the mixture was heated to 50°C and reacted for 4 hours. Then, 0.004 mol of trimethylolpropane (TMP) was added as a branching unit for a branching reaction for 4 hours. 0.0012 mol of dye B was dispersed in 0.09 mol of acetone and added to the three-necked flask, along with 0.025 mL of dibutyltin dilaurate. The mixture was reacted at 53°C for 7 hours. After the reaction was complete, the mixture was cooled to room temperature, and the acetone was distilled off under reduced pressure to obtain a polyurethane dispersant C with a branched structure anchored by the dye, with a molecular weight of 16388 Daltons.

[0073] Preparation and evaluation of water-based colorants containing dyes

[0074] Preparation of water-based colorants:

[0075] Example 4

[0076] The polyurethane dispersant A11g prepared in Example 1 was dispersed in 113g of water and stirred for 10min. Then, 76g of Disperse Orange 288 was added and dispersed for 30min. Then, 400g of zirconium beads were added and the mixture was milled at 3600r / min for 2h. After filtration, the water-based colorant was obtained.

[0077] Example 5

[0078] The polyurethane dispersant B14.5g prepared in Example 2 was dispersed in 95.5g of water and stirred for 10min. Then, 90g of dispersible violet 93 was added and dispersed for 30min. Then, 400g of zirconium beads were added and the mixture was milled at 3600r / min for 2h. After filtration, the water-based colorant was obtained.

[0079] Example 6

[0080] The polyurethane dispersant C15g prepared in Example 3 was dispersed in 85g of water and stirred for 10min. Then, 100g of Disperse Blue 291 was added and dispersed for 30min. Then, 400g of zirconium beads were added and the mixture was milled at 3600r / min for 2h. After filtration, the water-based colorant was obtained.

[0081] Comparative Example 1 (compared to Example 4, using a commercially available polyurethane dispersant)

[0082] Weigh 11g of ZetaSpere 3100 polyurethane dispersant and disperse it in 113g of water. After stirring for 10 minutes, add 76g of Disperse Orange 288 and disperse for 30 minutes. Then add 400g of zirconium beads and mill at 3600r / min for 2 hours. Filter to obtain the water-based colorant.

[0083] Comparative Example 2 (compared to Example 5, using a commercially available polyurethane dispersant)

[0084] Weigh 14.5g of ZetaSpere 3100 polyurethane dispersant and disperse it in 95.5g of water. After stirring for 10 minutes, add 90g of Disperse Violet 93 and disperse for 30 minutes. Then add 400g of zirconium beads and mill at 3600r / min for 2 hours. Filter to obtain the water-based colorant.

[0085] Comparative Example 3 (compared to Example 6, using a commercially available polyurethane dispersant)

[0086] Weigh 15g of ZetaSpere 3100 polyurethane dispersant and disperse it in 85g of water. After stirring for 10 minutes, add 100g of Disperse Blue 291 and disperse for 30 minutes. Then add 400g of zirconium beads and mill at 3600r / min for 2 hours. Since the slurry cannot be dispersed evenly, a uniformly dispersed water-based colorant was not obtained.

[0087] Comparative Example 4 (compared to Example 4, using a commercially available polyurethane emulsion)

[0088] Weigh 11g of HEBENS-339B polyurethane emulsion and disperse it in 113g of water. After stirring for 10 minutes, add 76g of Disperse Orange 288 and disperse for 30 minutes. Then add 400g of zirconium beads and mill at 3600r / min for 2 hours. Filter to obtain the water-based colorant.

[0089] Comparative Example 5 (compared to Example 5, using a commercially available polyurethane emulsion)

[0090] Weigh 14.5g of HEBENS-339B polyurethane emulsion and disperse it in 95.5g of water. After stirring for 10 minutes, add 90g of Disperse Violet 93 and disperse for 30 minutes. Then add 400g of zirconium beads and mill at 3600r / min for 2 hours. Filter to obtain the water-based colorant.

[0091] Comparative Example 6 (compared to Example 6, using a commercially available polyurethane emulsion)

[0092] Weigh 15g of HEBENS-339B polyurethane emulsion and disperse it in 85g of water. After stirring for 10 minutes, add 100g of Dispersible Blue 291 and disperse for 30 minutes. Then add 400g of zirconium beads and mill at 3600r / min for 2 hours. Since the slurry cannot be dispersed evenly, a uniformly dispersed water-based dispersant was not obtained.

[0093] Polyester fabric hot melt dyeing

[0094] Because Comparative Examples 3 and 6 had relatively high dye content, a uniform slurry could not be obtained during the preparation of the water-based colorant; therefore, no application performance tests were conducted. Distilled water was added to the water-based colorants prepared in Examples 4-6 and Comparative Examples 1, 2, 4, and 5 to prepare a uniform padding solution with a disperse dye concentration of 5%. Polyester fabric was uniformly immersed in the padding solution for 1 minute, then padded, and then immersed again for 1 minute for a second padding (the padding rate is generally controlled at 65%-70%). The fabric was pre-dried at 90℃-100℃ until dry, and then baked at 190℃-210℃ for 90 seconds. The hot-melt dyed samples were thoroughly washed with water, spun dry, and then subjected to the following tests.

[0095] L-value test: The L (brightness) value of the above 7 polyester fabrics was tested using a colorimeter with a D65 light source and a 10° viewing angle. Three points were selected for testing for each sample, and the average value was taken.

[0096] Color fastness to rubbing test: According to GB / T29865-2013 "Color fastness test of textiles - small area method for color fastness to rubbing", the dry and wet color fastness to rubbing of the polyester dyed fabrics corresponding to Examples 4-6 and Comparative Examples 1, 2, 4, and 5 were tested.

[0097] Color fastness to washing test: According to GB / T5713-2013 "Textiles - Tests for color fastness to water", the color fastness to washing of the polyester dyed fabrics corresponding to Examples 4-6 and Comparative Examples 1, 2, 4, and 5 was tested.

[0098] The test results of various performance tests of the polyester dyed fabrics corresponding to Examples 4-6 and Comparative Examples 1, 2, 4, and 5 are shown in Table 1.

[0099] Table 1

[0100]

[0101] The test results show that, compared with conventional polyurethane dispersants and polyurethane emulsions, the water-based colorant prepared by the polyurethane dispersant of this invention exhibits a lower L (lightness) value and superior color fastness to rubbing and washing after fabric dyeing. A comparison with Comparative Examples 3 and 6 shows that the polyurethane dispersant of this invention can prepare high-concentration water-based colorants. In summary, using the branched polyurethane dispersant prepared by this invention can improve the color depth of dyed fibers while ensuring excellent color fastness.

[0102] Preparation and evaluation of water-based colorants containing pigments

[0103] Preparation of water-based colorants:

[0104] Example 7

[0105] 5.5g of polyurethane dispersant A prepared in Example 1 was dispersed in 56.5g of water and stirred for 10min. Then, 38g of pigment yellow 74 was added and dispersed for 30min. Then, 200g of zirconium beads were added and the mixture was sand-milled at 3600r / min for 2h. After filtration, the water-based colorant was obtained.

[0106] Example 8

[0107] 6.5g of polyurethane dispersant B prepared in Example 2 was dispersed in 48.5g of water and stirred for 10min. Then, 45g of pigment violet 23 was added and dispersed for 30min. Then, 200g of zirconium beads were added and the mixture was milled at 3600r / min for 2h. After filtration, the water-based colorant was obtained.

[0108] Example 9

[0109] 7.5g of polyurethane dispersant C prepared in Example 3 was dispersed in 42.5g of water and stirred for 10min. Then, 50g of phthalocyanine blue 15:3 was added and dispersed for 30min. Then, 200g of zirconium beads were added and the mixture was milled at 3600r / min for 2h. After filtration, the water-based colorant was obtained.

[0110] Comparative Example 7 (compared to Example 7, using commercially available conventional...) 4060 dispersant)

[0111] Weigh out 5.5g Dispersant 4060 was dispersed in 56.5g of water and stirred for 10 minutes. Then, 38g of Pigment Yellow 74 was added and dispersed for 30 minutes. Finally, 200g of zirconium beads were added and the mixture was milled at 3600r / min for 2 hours. After filtration, the water-based colorant was obtained.

[0112] Comparative Example 8 (compared to Example 8, using commercially available conventional...) 4060 dispersant)

[0113] Weigh out 6.5g Dispersant 4060 was dispersed in 48.5g of water and stirred for 10 minutes. Then, 45g of pigment Violet 23 was added and dispersed for 30 minutes. Finally, 200g of zirconium beads were added and the mixture was milled at 3600r / min for 2 hours. After filtration, the water-based colorant was obtained.

[0114] Comparative Example 9 (compared to Example 9, using commercially available conventional...) 4060 dispersant)

[0115] Weigh out 7.5g 4060 dispersant was dispersed in 42.5g of water and stirred for 10min. Then, 50g of phthalocyanine blue 15:3 was added and dispersed for 30min. Then, 200g of zirconium beads were added and the mixture was sand-milled at 3600r / min for 2h. Since the slurry could not be evenly dispersed, a uniformly dispersed water-based colorant was not obtained and no further evaluation was conducted.

[0116] Performance evaluation:

[0117] Fineness test: A 100μm fineness plate was used to test the fineness of water-based colorants according to the national standard GB / T 6753.1-2007 Determination of grinding fineness of paints, varnishes and printing inks.

[0118] Viscosity test: The viscosity of water-based colorants was tested according to the national standard GB / T 9269-2009 Determination of viscosity of coatings by Stormer viscometer method (method B) using a digital viscometer.

[0119] Relative tinting strength: The relative tinting strength change of water-based colorants was tested according to Method B (instrumental method) described in Appendix B of HG / T 3951-2007 Water-based Pigments for Architectural Coatings; with Examples 7 and 8 as standard pigments, the relative tinting strength of Comparative Examples 7 and 8 was tested.

[0120] Stability Tests: ① Relative Coloring Strength: The relative coloring strength of the water-based colorants was tested after 1 day of preparation and after 90 days of storage at room temperature. Using the water-based colorants of each example and comparative example prepared 1 day prior as standard color pastes with a coloring strength of 100%, the relative coloring strength of the corresponding water-based colorants after 90 days of storage at room temperature was tested. ② State: After the water-based colorants were sealed and placed at 25°C for 30 days and 90 days respectively, the storage stability of the water-based colorants was determined by visually observing for any obvious pigment particle precipitation, flocculation, or other conditions that seriously affect stability. √ indicates no precipitation or flocculation; ○ indicates visible precipitation or flocculation, but requires careful observation to detect; × indicates clearly visible precipitation or flocculation.

[0121] The test results are shown in Table 2.

[0122] Table 2

[0123]

[0124] The test results of Examples 7-9 and Comparative Examples 7-9 show that, compared with commercially available dispersants, the polyurethane dispersant with a branched structure prepared in this invention can reduce the viscosity of the system and can be used to prepare high-concentration water-based colorants. The water-based colorants prepared from the polyurethane dispersant of this invention have low fineness, high relative coloring strength, and excellent storage stability.

[0125] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any modifications or equivalent transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing a polyurethane dispersant with a branched structure, characterized in that, Includes the following steps: (1) The isocyanate compound was reacted with the polyol at a temperature of 50~75℃ to obtain the polyurethane prepolymer; (2) React the polyurethane prepolymer obtained in step (1) with a crosslinking agent to obtain a polyurethane compound with a branched structure; (3) Dissolve the dye containing active groups in an organic solvent, and then add the polyurethane compound with a branched structure obtained in step (2) to react; (4) After the reaction is complete, the mixture is cooled to room temperature and distilled under reduced pressure to obtain a polyurethane dispersant with a branched structure; The dye containing the active group has the structure shown in general formula (Ⅰ); ； （Ⅰ） Wherein, R1 is H and R2 is H, or R1 is OCH3 and R2 is NHCOCH3; The polyol is polyethylene glycol with a molecular weight of 400-1000 Daltons.

2. The method for preparing a polyurethane dispersant with a branched structure according to claim 1, characterized in that, The isocyanate compound is selected from at least one of isophorone diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, dicyclohexylmethane diisocyanate, benzene diisocyanate, 1,5-naphthalene diisocyanate, and terephthalic diisocyanate.

3. The method for preparing a polyurethane dispersant with a branched structure according to claim 1, characterized in that, The crosslinking agent is selected from at least one of trimethylolpropane, triethanolamine, glycerol, and diethylenetriamine.

4. The method for preparing a polyurethane dispersant with a branched structure according to claim 1, characterized in that, The molar ratio of the isocyanate group of the isocyanate compound, the hydroxyl group of the polyol, the hydroxyl group of the crosslinking agent, and the active group of the dye is (10~20):(3~10):(3~8):

1.

5. The method for preparing a polyurethane dispersant with a branched structure according to claim 1, characterized in that, The reaction temperature in step (3) is 50~80℃.

6. A polyurethane dispersant with a branched structure, characterized in that, It is prepared using the preparation method described in any one of claims 1 to 5.

7. A water-based colorant, characterized in that, Includes coloring substances and the polyurethane dispersant as described in claim 6.

8. The application of the water-based colorant according to claim 7 in fabric dyeing and architectural coating coloring.

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