A comb-shaped aqueous polyurethane dispersant for disperse dyes and a method for preparing the same

Abstract

The application discloses a comb-type water-based polyurethane dispersant for disperse dyes and a preparation method thereof. An intermediate I is synthesized from polyethylene glycol monomethyl ether and trimellitic anhydride, 1,2-propylene glycol borate is synthesized from boric acid and 1,2-propylene glycol, and then an intermediate II is synthesized from the 1,2-propylene glycol borate; then isophorone diisocyanate, polyether diol and the intermediate II are reacted, chain extension, end capping and high-speed emulsification are carried out, and the comb-type water-based polyurethane dispersant obtained has a block structure containing a phenyl group and a polyoxyethylene side chain; the phenyl group serves as an anchoring group to provide an adsorption site for the adsorption of the dispersant to the disperse dyes, and the dispersant is anchored by intermolecular forces and pi-pi stacking. The polyoxyethylene side chain serves as a solvation chain to stretch in a liquid phase to form a solvation layer to provide steric hindrance. Meanwhile, the carboxyl groups on the polyurethane molecular chain are ionized to form a double electric layer on the surface of the dye particles, and the double electric layer cooperates with the steric hindrance to prevent the dye particles from agglomerating and precipitating.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of textile printing and dyeing auxiliaries, in particular to a comb-type water-based polyurethane dispersant for disperse dyes and a preparation method thereof. BACKGROUND

[0002] Disperse dyes are small molecules, which are in a non-ionic state with very low solubility in water. In order to disperse the dyes in water, the dye particles must be ground to a certain fineness (usually below 2 μm), and the uniform and stable suspension is formed with the help of dispersants. Small molecule dispersants cannot provide enough adsorption sites and long enough solvation chains, and only rely on electrostatic stabilization mechanism and small steric hindrance, so the adsorption force on the particle surface is weak and easy to desorb. The polymeric dispersant has a high molecular weight, more anchoring sites and long enough solvation chains, thereby providing steric hindrance and having higher adsorption efficiency. The polymeric dispersants commonly used for dye dispersion are mainly sodium lignosulfonate, naphthalene formaldehyde condensate and phenolic aldehyde condensate sulfonate. However, these dispersants also have some problems, such as poor water solubility of sodium lignosulfonate, staining of some fibers, free formaldehyde in naphthalene formaldehyde condensate and phenolic aldehyde condensate sulfonate, and reduction of some dyes. SUMMARY

[0003] The present application provides a comb-type water-based polyurethane dispersant and a preparation method thereof, which can effectively disperse disperse dyes and improve storage stability.

[0004] The present application also provides a preparation method of the comb-type water-based polyurethane dispersant, which comprises the following steps:

[0005] (1) 40-60 parts by mass of polyethylene glycol monomethyl ether, 14-17 parts by mass of trimellitic anhydride and 40-60 parts by mass of ethyl acetate are added into a reaction container with a stirrer and a condensation reflux device, the condensation reflux device and the stirrer are turned on, and the reaction is carried out at a temperature of 80-90 DEG C for 3-4 hours, then the temperature is adjusted to 50-60 DEG C and the pressure is adjusted to -0.08 to -0.1 MPa, and the recovered ethyl acetate is removed by distillation under reduced pressure to obtain intermediate I;

[0006] (2) add 3-5 parts of boric acid and 10-16 parts of 1,2-propylene glycol into a reaction vessel with a stirrer, and react for 2-3 hours at a temperature of 120-130℃ under stirring to obtain 1,2-propylene glycol borate; add 11-13 parts of 1,2-propylene glycol borate, 40-60 parts of intermediate I, and 0.5-0.75 parts of p-toluene sulfonic acid into a reaction vessel with a stirrer, and react for 2-3 hours at a temperature of 130-140℃ under stirring; cool the reaction solution to below 90℃, add 6080 parts of deionized water, install a condensation reflux device, open the condensation reflux, adjust the temperature to 95-100℃, react for 2 hours under the condition of keeping the temperature, cool to 20-30℃, and add 80-110 parts of saturated sodium carbonate solution; adjust the temperature to 60-70℃ and the pressure to -0.08 to -0.1 MPa, remove water by distillation under reduced pressure, dissolve with anhydrous methanol, filter, warm the filtrate to 30-40℃, and remove and recover methanol by distillation under reduced pressure under the condition of a pressure of -0.08 to -0.1 MPa to obtain intermediate II;

[0007] (3) add 40-60 parts of intermediate II, 40-60 parts of acetone, 18 parts of polyether glycol, and 0.06-0.12 parts of dibutyl tin dilaurate into a reaction vessel with a stirrer, a condensation reflux device, and a dropping funnel; open the condensation reflux device and the stirrer, warm to 70-80℃, then gradually add 32 parts of isophorone diisocyanate, and dropwise add within 50-80 minutes, react for 2-3 hours under the condition of keeping the temperature at 70-80℃; completely dissolve 4-7 parts of 2,2-dimethylol propionic acid in 5-8 parts of N,N-dimethylformamide, and add into the reaction vessel, adjust the temperature to 80-90℃, react for 1.5-2 hours under the condition of keeping the temperature, then add 5-9 parts of methyl ethyl ketoxime into the reaction vessel to continue the reaction for 1-1.5 hours; after the reaction solution is cooled to 40-50℃, add 3-5 parts of triethylamine into the reaction vessel, react for 0.5-1 hour under the condition of a temperature of 40-50℃, then remove and recover acetone by distillation under reduced pressure, add 250-290 parts of deionized water, and stir at a speed of 1500-3000 r / min for 0.5-1 hour to obtain a comb-shaped water-based polyurethane dispersant.

[0008] In the above technical solution, the number average molecular weight of the polyethylene glycol monomethyl ether in step (1) is 500, 550, 600, 650, 700, or 750; and the polyether glycol used in step (3) is polypropylene glycol with a number average molecular weight of 1000.

[0009] The technical solution of the present application also includes a comb-shaped water-based polyurethane dispersant for disperse dyes obtained by the above preparation method.

[0010] The synthetic reaction route of the comb-shaped waterborne polyurethane dispersant for dispersing dyes prepared by the technical scheme of the present application is as follows:

[0011] (1) Synthesis of intermediate I

[0012]

[0013] (2) Synthesis of intermediate II

[0014]

[0015] (3) Synthesis of the comb-shaped waterborne polyurethane dispersant

[0016]

[0017] R1 is:

[0018]

[0019] wherein k = 17; 12 ≤ n ≤ 17; 8 ≤ a ≤ 14.

[0020] The principle of the present application is that the carbon on the anhydride in trimellitic anhydride has a stronger positive tendency, and is more easily attacked by a nucleophile, and the anhydride in its structure is more easily reacted with polyethylene glycol monomethyl ether than the carboxyl group. According to the different reactivity of the anhydride and the carboxyl group in trimellitic anhydride to the hydroxyl group, and by controlling the feeding ratio, intermediate I is synthesized through mono-esterification reaction. The primary hydroxyl group on the 1,2-propanediol molecule is reacted with boric acid to form 1,2-propanediol borate, which is esterified with intermediate I under the catalysis of p-toluenesulfonic acid, and intermediate II is obtained through hydrolysis. By virtue of the high reactivity of the isocyanate group with the hydroxyl group and the oxime group, first, the polyurethane prepolymer having an isocyanate group at the end is synthesized by controlling the molar ratio of the polyether diol, isophorone diisocyanate, and intermediate II, and the feeding sequence; then, the isocyanate group in the prepolymer is reacted with the hydroxyl group of 2,2-dimethylol propionic acid for chain extension; finally, the isocyanate at the end of the molecule is capped with methyl ethyl ketone oxime, and the comb-shaped waterborne polyurethane dispersant is prepared through emulsification. The present application introduces phenyl and polyoxyethylene chain into the block structure of the polyurethane, the dispersant is anchored at multiple points by virtue of the intermolecular forces and the π-π stacking effect provided by the phenyl group, and is firmly adsorbed on the surface of the dispersed dye particles; the polyoxyethylene chain stretches in the liquid phase to form a solvation layer, and generates steric hindrance to prevent the aggregation between the dye particles. The chain extension with 2,2-dimethylol propionic acid not only enhances the water solubility of the polyurethane, but also forms a double electric layer in water by ionization, and relies on the electrostatic repulsion to maintain the metastable state between the particles in the dispersion system.

[0021] The comb-type waterborne polyurethane dispersant for dispersing dyes has a comb structure, and has high dispersing efficiency; the anchoring sites of the polyurethane are many, the structure of the polymer chain is easy to modify and change through long molecular chains and solvated segments, and effective steric hindrance can be formed to prevent flocculation and precipitation between particles.

[0022] Compared with the prior art, the application has the following advantages due to the application of the technical scheme:

[0023] 1. The phenyl in the block structure of the comb-type waterborne polyurethane dispersant can be anchored on the surface of the dispersed dye particles in multiple points and fixed on the dye particles; the polyurethane dispersant has a high molecular weight, has a stronger intermolecular force with the dye particles; the polyoxyethylene side chain provides solvation and steric hindrance to hinder the re-agglomeration of the dispersed particles; the carboxyl in the polyurethane molecular chain is ionized in a liquid phase to provide effective electrostatic force, and the metastable state of the dispersion system is realized by the synergistic effect of the electrostatic repulsion between particles and the steric hindrance of the solvated chain, so that the stability is good and storage is facilitated.

[0024] 2. The comb-type waterborne polyurethane dispersant can control the grafting density of the comb structure by controlling the feeding ratio of the intermediate and the polyether polyol, and different side chain lengths of the polyurethane dispersant can be obtained by using polyethylene glycol monomethyl ether with different molecular weights. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The infrared spectrum of the comb-type waterborne polyurethane dispersant provided for the embodiment 1 of the application is shown in the figure;

[0026] Figure 2 The infrared spectrum of the comb-type waterborne polyurethane dispersant provided for the embodiment 2 of the application is shown in the figure;

[0027] Figure 3 The infrared spectrum of the comb-type waterborne polyurethane dispersant provided for the embodiment 3 of the application is shown in the figure. DETAILED DESCRIPTION

[0028] The technical scheme of the application will be further described below in combination with the drawings and specific embodiments.

[0029] Embodiment 1

[0030] (1) 20 g of polyethylene glycol monomethyl ether 500, 7.69 g of trimellitic anhydride, and 20 g of ethyl acetate were added to a reaction container with a stirrer and a condensation reflux device, the condensation reflux device and the stirrer were turned on, and after reaction at 80℃ for 4 h, the temperature was adjusted to 50℃ and the pressure was adjusted to-0.1 MPa, and the recovered ethyl acetate was removed by distillation under reduced pressure to obtain an intermediate I.

[0031] (2) 2.1 g of boric acid and 7.61 g of 1,2-propanediol were added to a reaction vessel equipped with a stirrer and stirred. After reacting at 120 °C for 3 h, 1,2-propanediol borate ester was obtained. 5.54 g of 1,2-propanediol borate ester, 20 g of intermediate I, and 0.26 g of p-toluenesulfonic acid were added to a reaction vessel equipped with a stirrer and stirred. After reacting at 130 °C for 3 h, the reaction solution was cooled to below 90 °C, 30 g of deionized water was added, a reflux condenser was installed, the reflux condenser was turned on, the temperature was adjusted to 95 °C, and the reaction was maintained at this temperature for 2 h. After cooling to 25 °C, 41 g of saturated sodium carbonate solution was added. The temperature was adjusted to 60 °C and the pressure to -0.1 MPa. Water was removed by vacuum distillation. The solution was dissolved in anhydrous methanol and filtered. The filtrate was heated to 50 °C and the methanol was removed by vacuum distillation under a pressure of -0.1 MPa to obtain intermediate II.

[0032] (3) Add 21.82g of intermediate II, 20g of acetone, 9g of polypropylene glycol 1000, and 0.06g of dibutyltin dilaurate to a reaction vessel equipped with a stirrer, a reflux condenser, and a dropping funnel; turn on the reflux condenser and stirrer, raise the temperature to 70℃, and gradually add 16g of isophorone diisocyanate, completing the addition within 60min. Maintain the reaction at this temperature for 3h; completely dissolve 3.22g of 2,2-dimethylolpropionic acid in 3.5g of... After adding N,N-dimethylformamide to the reaction vessel, the temperature was adjusted to 80℃ and the reaction was maintained at this temperature for 2 hours. Then, 2.51g of methyl ethyl ketone oxime was added to the reaction vessel and the reaction was maintained at this temperature for another 1.5 hours. After the reaction solution cooled to 40℃, 2.43g of triethylamine was added to the reaction vessel and the reaction was maintained at 40℃ for 30 minutes. Then, the temperature was adjusted to 45℃ and the pressure was -0.1 MPa. After removing and recovering acetone by vacuum distillation, 128.31g of deionized water was added and the mixture was stirred at a high speed of 1500 r / min for 60 minutes to obtain a comb-shaped waterborne polyurethane dispersant.

[0033] See appendix Figure 1 This is the infrared spectrum of the comb-type waterborne polyurethane dispersant in this embodiment. At 3359 cm⁻¹ -1 1554cm -1 The peak at 1714 cm⁻¹ represents the stretching and deformation vibrations of N-H in carbamate. -1 The peak at 1243 cm⁻¹ represents the stretching vibration of C=O in urethane esters, and the above three peaks are characteristic absorption peaks of urethane esters. The asymmetric stretching vibration peak of C=N in urethane esters is at 1243 cm⁻¹. -1 Location. 2949cm -1 2873cm -1 The peak at 1661 cm⁻¹ represents the C-H stretching vibration of -CH₃ and -CH₂. -1at 1456 cm -1 at 1361 cm -1 to the left and right are C-H ring skeleton vibrations in the aromatic ring. The stretching and bending vibration peaks of C─O─C in the polyether chain are at 1094 cm -1 at 947 cm -1 at 846 cm -1 at 2300-2250 cm -1 No characteristic absorption peak of ─NCO was found at this position, indicating that ─NCO had been completely reacted. That is, the target product was synthesized.

[0034] Example 2

[0035] (1) 23 g of polyethylene glycol monomethyl ether 550, 8.03 g of trimellitic anhydride, and 30 g of ethyl acetate were added to a reaction vessel equipped with a stirrer and a condensation reflux device. The condensation reflux device and the stirrer were turned on, and after reaction at 90°C for 3 h, the temperature was adjusted to 55°C and the pressure was adjusted to -0.09 MPa. Ethyl acetate was removed by distillation under reduced pressure to obtain intermediate I.

[0036] (2) 1.75 g of boric acid and 6.09 g of 1,2-propanediol were added to a reaction vessel equipped with a stirrer, and stirring was started. After reaction at 125°C for 2.5 h, 1,2-propanediol borate was obtained. 6.3 g of 1,2-propanediol borate, 25 g of intermediate I, and 0.31 g of p-toluenesulfonic acid were added to a reaction vessel equipped with a stirrer, and stirring was started. After reaction at 140°C for 2 h, the reaction liquid was cooled to below 90°C, 35 g of deionized water was added, a condensation reflux device was installed, the condensation reflux was turned on, the temperature was adjusted to 100°C, and after reaction at this temperature for 2 h, it was cooled to 20°C, and 47 g of saturated sodium carbonate solution was added. The temperature was adjusted to 65°C and the pressure was adjusted to -0.09 MPa. After removing water by distillation under reduced pressure, it was dissolved in anhydrous methanol and filtered. The filtrate was heated to 55°C, and methanol was recovered by distillation under reduced pressure at a pressure of -0.09 MPa to obtain intermediate II.

[0037] (3) Add 23.16g of intermediate II, 25g of acetone, 9g of polypropylene glycol 1000, and 0.08g of dibutyltin dilaurate to a reaction vessel equipped with a stirrer, a reflux condenser, and a dropping funnel; turn on the reflux condenser and stirrer, raise the temperature to 75°C, and gradually add 16g of isophorone diisocyanate, completing the addition within 60 minutes. Maintain the reaction at this temperature for 2.5 hours; completely dissolve 2.6g of 2,2-dimethylolpropionic acid in 3.0g of... After adding N,N-dimethylformamide to the reaction vessel, the temperature was adjusted to 85℃ and the reaction was maintained at this temperature for 1.8h. Then, 3.35g of methyl ethyl ketone oxime was added to the reaction vessel and the reaction was maintained at this temperature for another 1.3h. After the reaction solution was cooled to 50℃, 1.96g of triethylamine was added to the reaction vessel and the reaction was maintained at 50℃ for 30min. Then, the temperature was adjusted to 55℃ and the pressure was -0.09MPa. After removing and recovering acetone by vacuum distillation, 131.44g of deionized water was added and the mixture was stirred at a high speed of 3000r / min for 30min to obtain a comb-shaped waterborne polyurethane dispersant.

[0038] See appendix Figure 2 This is the infrared spectrum of the comb-type waterborne polyurethane dispersant in this embodiment. At 3337 cm⁻¹ -1 1538cm -1 The peak at 1710 cm⁻¹ represents the stretching and deformation vibrations of N-H in carbamate. -1 The peak at 1237 cm⁻¹ represents the stretching vibration of C=O in urethane esters, and the above three peaks are characteristic absorption peaks of urethane esters. The asymmetric stretching vibration peak of C=N in urethane esters is at 1237 cm⁻¹. -1 Location. 2967cm -1 2869cm -1 The peak at 1641 cm⁻¹ represents the C-H stretching vibration of -CH₃ and -CH₂. -1 The peak of the stretching vibration at C=N is 1457 cm⁻¹. -1 The peak at 1373 cm⁻¹ represents the stretching vibration peak of the C=C ring in the benzene ring. -1 The left and right sides represent the CH ring skeletal vibrations in the aromatic ring. The stretching and bending vibration peaks of the C-O-C chain in the polyether chain are at 1094 cm⁻¹. -1 Broad peak, 926cm -1 868cm -1 Location. 2300~2250cm -1 No characteristic absorption peak of -NCO was found, indicating that -NCO had reacted completely. Therefore, the target product was synthesized.

[0039] Example 3

[0040] (1) Put 28 g of polyethylene glycol monomethyl ether 750, 7.17 g of trimellitic anhydride, 35 g of ethyl acetate into a reaction vessel with a stirrer and a condensing reflux device, start the condensing reflux device and the stirrer, after 3.5 h of reaction at 85℃, adjust the temperature to 60℃ and the pressure to -0.08 MPa, remove the recovered ethyl acetate by distillation under reduced pressure to obtain intermediate I.

[0041] (2) Put 1.54 g of boric acid and 5.32 g of 1,2-propanediol into a reaction vessel with a stirrer, start stirring, and after 2.5 h of reaction at 125℃, 1,2-propanediol borate is obtained; put 6.01 g of 1,2-propanediol borate, 30 g of intermediate I, and 0.36 g of p-toluenesulfonic acid into a reaction vessel with a stirrer, start stirring, and after 2.5 h of reaction at 135℃; cool the reaction liquid to below 90℃, add 40 g of deionized water, install a condensing reflux device, start the condensing reflux, adjust the temperature to 98℃, and after 2 h of reaction at this temperature, cool to 30℃, and add 55 g of saturated sodium carbonate solution; adjust the temperature to 70℃ and the pressure to -0.08 MPa, remove the water by distillation under reduced pressure, dissolve in anhydrous methanol, filter, warm the filtrate to 50℃, and remove the recovered methanol by distillation under reduced pressure at a pressure of -0.08 MPa to obtain intermediate II.

[0042] (3) Put 28.56 g of intermediate II, 30 g of acetone, 9 g of polypropylene glycol 1000, and 0.12 g of dibutyltin dilaurate into a reaction vessel with a stirrer, a condensing reflux device, and a dropping funnel; start the condensing reflux device and the stirrer, warm to 80℃, gradually add 16 g of isophorone diisocyanate, and add dropwise within 60 min, and after 2 h of reaction at this temperature; completely dissolve 2.07 g of 2,2-dimethylolpropionic acid in 2.5 g of N,N-dimethylformamide, and add to the reaction vessel, adjust the temperature to 90℃, and after 1.5 h of reaction at this temperature, add 4.31 g of methylethyl ketoxime to the reaction vessel and continue to react for 1 h; after the reaction liquid is cooled to 45℃, add 1.56 g of triethylamine to the reaction vessel, and after 30 min of reaction at 45℃, adjust the temperature to 55℃ and the pressure to -0.08 MPa, remove the recovered acetone by distillation under reduced pressure, add 144 g of deionized water, and stir at a speed of 2000 r / min for 40 min to obtain the comb-shaped water-based polyurethane dispersant.

[0043] See Figure 1 Figure 3 , which is the infrared spectrum of the comb-shaped water-based polyurethane dispersant in this embodiment. The peaks at 3337 cm -1 , 1538 cm -1 , and 1707 cm -1The peak at 1720 cm-1 is the stretching vibration peak of C=0 in urethane, and the above three peaks are characteristic absorption peaks of urethane. The asymmetric stretching vibration peak of C=N in urethane is at 1259 cm -1 The peaks at 2965 cm -1 , 2874 cm -1 are the C-H stretching vibration peaks of -CH3 and -CH2, the peak at 1650 cm -1 is the stretching vibration peak of C=N, the peak at 1454 cm -1 is the stretching vibration peak of C=C in the benzene ring, and the peaks at 1373 cm -1 and 1310 cm-1 are the C-H ring skeleton vibrations in the aromatic ring. The stretching vibration and bending vibration peaks of C-O-C in the polyether chain are at 1093 cm -1 broad peak, 928 cm -1 , 865 cm -1 . The characteristic absorption peak of -NCO is not found at 2300-2250 cm -1 , indicating that -NCO has been completely reacted. That is, the target product is synthesized.

[0044] Example 4

[0045] In this example, C.I. Disperse Blue 56 is taken as an example to test the dispersion performance of the comb-shaped waterborne polyurethane dispersant for disperse dyes prepared by the examples 1, 2 and 3 of the present application.

[0046] 1. Grinding process

[0047] The specific grinding process is as follows: first step: add the amount of deionized water, dispersant and disperse dye in the formula to the container, and pre-disperse with a stirrer; second step: add the amount of disperse dye, dispersant and deionized water in the formula to the grinding cup, and grind with a ball mill for 2 hours with zirconium beads accounting for 4 / 5 of the whole system. The dye dispersion is obtained by filtration.

[0048] The specific formula (mass percentage) of the disperse dye dispersion is as follows:

[0049] Disperse dye: 20%

[0050] Dispersant: 8%

[0051] Deionized water: 72%

[0052] 2. Centrifugal stability test

[0053] The dye dispersion diluted 2000 times is centrifuged at different speeds using a high-speed centrifuge. The centrifugal stability is evaluated according to the difference in absorbance of the upper and lower dye solutions. The larger the centrifugal stability value, the stronger the centrifugal stability. According to the formula, the centrifugal stability R of the dye dispersion is represented by the ratio of the absorbance before and after centrifugation A x / A0.

[0054] R / % = A x / A0 x 100

[0055] wherein: A x - maximum absorbance of supernatant after centrifugation, L / (g.cm); A0- maximum absorbance of supernatant before centrifugation, L / (g.cm).

[0056] The results of the centrifugal stability test of the dye dispersions prepared by dispersing the dyes with the comb-type waterborne polyurethane dispersants prepared in Examples 1, 2 and 3 and the comparative sample are shown in Table 1.

[0057] Table 1

[0058]

Claims

1. A process for the preparation of a comb-shaped aqueous polyurethane dispersant for disperse dyes, characterized in that Comprising the following steps: (1) according to the mass fraction, 40-60 parts of polyethylene glycol monomethyl ether, 14-17 parts of trimellitic anhydride, 40-60 parts of ethyl acetate are added to the reaction container with stirrer and condensation reflux device, open the condensation reflux device and stirrer, under the condition of temperature 80-90 ℃, reaction for 3-4 h, then adjust the temperature to 50-60 ℃, the pressure to -0.08- -0.1 MPa, remove the recovered ethyl acetate by distillation under reduced pressure, to obtain intermediate I; (2) 3-5 parts of boric acid and 10-16 parts of 1,2-propanediol are added to the reaction container with stirrer, under the condition of temperature 120-130 ℃, stirring for 2-3 h, to obtain 1,2-propanediol borate; 11-13 parts of 1,2-propanediol borate, 40-60 parts of intermediate I, 0.5-0.75 parts of p-toluenesulfonic acid are added to the reaction container with stirrer, under the condition of temperature 130-140 ℃, stirring for 2-3 h; the reaction liquid is cooled to below 90 ℃, 60-80 parts of deionized water is added, the condensation reflux device is installed, the condensation reflux is opened, the temperature is adjusted to 95-100 ℃, under the condition of maintaining temperature, reaction for 2 h, then cooled to 20-30 ℃, 80-110 parts of saturated sodium carbonate solution is added; adjust the temperature to 60-70 ℃, the pressure to -0.08- -0.1 MPa, remove the water by distillation under reduced pressure, dissolve in anhydrous methanol, then filter, the filtrate is heated to 30-40 ℃, under the condition of pressure -0.08- -0.1 MPa, remove the recovered methanol by distillation under reduced pressure, to obtain intermediate II; (3) 40-60 parts of intermediate II, 40-60 parts of acetone, 18 parts of polyether diol, 0.06-0.12 parts of dibutyltin dilaurate are added to the reaction container with stirrer, condensation reflux device, dropping funnel; open the condensation reflux device and stirrer, heat to 70-80 ℃, then gradually add 32 parts of isophorone diisocyanate, dropwise add within 50-80 min, under the condition of maintaining temperature 70-80 ℃, reaction for 2-3 h; 4-7 parts of 2,2-dimethylol propionic acid is completely dissolved in 5-8 parts of N,N-dimethylformamide, then added to the reaction container, adjust the temperature to 80-90 ℃, under the condition of maintaining temperature, reaction for 1.5-2 h, then add 5-9 parts of methyl ethyl ketoxime to the reaction container, continue to heat for 1-1.5 h; after the reaction liquid is cooled to 40-50 ℃, 3-5 parts of triethylamine is added to the reaction container, under the condition of temperature 40-50 ℃, heat for 0.5-1 h, then adjust the pressure to -0.08- -0.1 Mpa, remove the recovered acetone by distillation under reduced pressure, then add 250-290 parts of deionized water, under the condition of speed 1500-3000 r / min, high-speed stirring for 0.5-1 h, to obtain the comb-shaped water-based polyurethane dispersant.

2. A process for the preparation of a comb-shaped aqueous polyurethane dispersant for disperse dyes as claimed in claim 1, characterized in that: The number average molecular weight of the polyethylene glycol monomethyl ether described in step (1) is 500, 550, 600, 650, 700, 750.

3. A process for the preparation of a comb-type aqueous polyurethane dispersant for disperse dyes as claimed in claim 1, characterized in that: The polyether diol described in step (3) is polypropylene glycol with a number average molecular weight of 1000.

4. A comb-shaped waterborne polyurethane dispersant for disperse dyes, obtained by the method according to claim 1.

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