Liquid dispersant for disperse dyes, process for its preparation and use

Abstract

This invention discloses a superdispersant for liquid disperse dyes prepared by RAFT polymerization, its synthesis method, and its applications. The method includes: synthesizing a macromolecular copolymer 2-vinylnaphthalene-acrylic acid-maleic anhydride via RAFT polymerization, and then synthesizing the superdispersant 2-vinylnaphthalene-acrylic acid-maleic anhydride-polyethylene glycol via polymerization. The macromolecular copolymer 2-vinylnaphthalene-acrylic acid-maleic anhydride acts as a hydrophobic group, anchoring itself to the dye particle surface and tightly binding with the dye particles. The hydrophilic polyethylene glycol group acts as a solvation chain, forming steric hindrance to prevent dye aggregation and achieving good dispersion. Furthermore, the molecular weight of the superdispersant can be controlled through RAFT polymerization, allowing for the preparation of superdispersants with different molecular weights to meet various needs. This method is suitable for dispersing various disperse dyes, and the resulting liquid dispersed dye exhibits advantages such as low sedimentation and good stability.

Description

Technical Field

[0001] This invention relates to the field of liquid disperse dyes, and more specifically to a superdispersant for liquid disperse dyes prepared by RAFT polymerization, the method thereunder, and its application. Background Technology

[0002] Currently, disperse dyes on the market are mainly in powder form, which has advantages such as good storage stability, simple packaging, convenient transportation, and mature production technology. However, the amount of dispersant in powdered disperse dyes is approximately 200% of the dye mass, resulting in high energy consumption, high VOC emissions, and high carbon emissions during dye production. Furthermore, the application of powdered disperse dyes also presents problems such as dust pollution, high water consumption, and high dispersant content in wastewater, increasing application costs for enterprises. To address these issues, many foreign dye companies began developing liquid disperse dyes in the 1960s.

[0003] Compared with powdered dyes, liquid disperse dyes have the following advantages: 1. Good application performance: The dyes have better dispersibility and are less prone to clumping. 2. The amount of auxiliaries in liquid disperse dyes is much lower than that in powdered dyes, which can reduce dye migration during continuous pad dyeing. 3. Easy to prepare into nano-sized particles, improving dye uptake and fixation rates. 4. Reduced production costs: Compared with solid dyes, liquid dyes do not require spray drying, dry pulverization, or dry blending processes, which greatly shortens the production process, reduces the cost of dye commercialization, and increases production volume. 5. Reduced COD in residual liquor: Because liquid dyes use relatively fewer dye dispersants and other auxiliaries, the COD content in the dyeing residual liquor is naturally lower. Furthermore, it can significantly reduce the discharge of dyeing and printing wastewater and waste residue at the source.

[0004] Liquid disperse dyes, as an environmentally friendly type of dye, can effectively promote the development of the green textile industry. However, their promotion and use have been severely hampered by their poor storage stability and difficult transportation. To improve the storage stability of liquid disperse dyes, research on dispersants and their formulation, as well as dye dispersion processing methods, has increased in recent years. Suitable dispersants can not only improve the grinding efficiency of liquid disperse dyes but also ensure their good stability.

[0005] Currently, there are relatively few research reports on liquid disperse dyes both domestically and internationally. Klaus Hofmann et al. prepared liquid disperse dyes with an average particle size of less than 1 μm in 80% of the dye particles [Klaus Hofmann, Ulrich Buhler Liquid formulation of disperse dyestuffs containing organic oxides or silicates for dyeing textile materials. [P]. US:4812143, 1989-03-14]. These dyes showed no stratification even after being stored at room temperature and 50°C for several months, demonstrating good storage stability. Zhang Shuguang formulated liquid disperse dyes using C.1. Disperse Red 60 as the main component and conducted dyeing experiments. The results showed that dyes with smaller particle sizes dyed faster and produced more vibrant colors [Zhang Shuguang. Preparation and performance study of liquid ultrafine disperse dyes [D]. Jiangnan University. 2007]. Yu Songhua et al. selected a novel ternary composite dispersant composed of three surfactants to prepare liquid dye samples of disperse dyes. They compared the samples with commercial disperse dyes and conducted various dyeing tests. The results showed that the general dyeing performance of the prepared samples was basically equivalent to that of the commercial dyes, and the dye exhaustion rate was slightly better than that of the commercial dyes. [Yu Songhua, Wu Ailian. Preliminary study on novel dispersants for dye processing [J]. Shanghai Coatings. 2009, 37(6):30-35]. Zhu Liang prepared an ultrafine paste-like disperse dye for polyester dyeing. It had pure color, high color yield, low dye consumption, and low wastewater discharge. [Zhu Liang. An ultrafine paste-like disperse dye for polyester dyeing [P]. CN101831203A. 2009.03.12]. Wang Kunchen prepared liquid azo and anthraquinone disperse dyes using lignin sulfonate as a dispersant and polyethylene glycol ether as a co-dispersant [Wang Kunchen. Liguid dispersed dye of the azo or anthraquinone type [P]. US006066183A. 1998.04.13]. The system exhibited good dispersion stability, with no sedimentation observed after a period of time.

[0006] Chinese invention patent application No. 201811205617.1 discloses an acrylic acid-maleic anhydride copolymer pigment dispersant, which has good dispersion performance and good stability. Chinese invention patent application No. 201910113263.6 discloses a pigment polymeric dispersant with good dispersion performance and low viscosity and high efficiency in the prepared organic pigment system. Chinese patent application No. 202110584812.5 discloses a polymeric dispersant for liquid disperse dyes, which has high grinding efficiency in the preparation of liquid disperse dyes and good storage stability of the dyes.

[0007] The hydrophobic groups of superdispersants can form anchors on the surface of dye particles, enabling the dispersant and dye particles to bind stably together. Conversely, the hydrophilic groups of superdispersants can form solvation chains, creating steric hindrance between dye particles and effectively preventing their aggregation. However, the molecular weight of superdispersants prepared by polymerization reactions is currently uncontrollable. Superdispersants prepared by RAFT polymerization, on the other hand, have the advantages of tunable structure and controllable molecular weight compared to those currently on the market. Random, block, or gradient block copolymers can be prepared as needed, and the superdispersant with the best dispersion effect can be obtained by observing the dispersion effects of superdispersants with different molecular weights. Summary of the Invention

[0008] The technical problem to be solved by this invention is to provide a superdispersant with controllable molecular weight prepared by RAFT polymerization, which overcomes the shortcomings of traditional superdispersants with uncontrollable molecular weight, thereby allowing the selection of superdispersants with different molecular weights according to the needs of different disperse dyes.

[0009] The general structural formula of the hyperdispersant is specifically shown in Formula I:

[0010]

[0011] in:

[0012] D is an acrylic monomer, such as acrylic acid or methacrylic acid; E is a monomer containing at least one benzene ring, such as styrene, 2-vinylnaphthalene, or 4-vinylbiphenyl; this carbon chain has a hydrophobic end, anchoring the dye particles; Q is a hydrophilic polymer, such as polyethylene glycol or polyvinyl alcohol, having a hydrophilic end. The resulting solvation chain creates steric hindrance between dye particles, effectively preventing aggregation. Where x is an integer from 1 to 4, y is an integer from 1 to 12, and z is an integer from 1 to 5. Further preferably, when the benzene-containing monomer is 2-vinylnaphthalene and the hydrophilic polymer is polyethylene glycol, the structural formula of the superdispersant is as follows:

[0013]

[0014] A method for synthesizing a superdispersant for preparing liquid disperse dyes by RAFT polymerization and its application, comprising the following steps:

[0015] (1) A macromolecular copolymer with a weight average molecular weight of 1000-30000 g / mol was synthesized by RAFT reagent butyl-(1-phenylethyl) trithiocarbonate through RAFT free radical polymerization-induced self-assembly.

[0016] (2) The obtained macromolecular copolymer and polyethylene glycol were dissolved in a certain amount of acetone, and finally a catalyst was added to carry out the reaction. The reaction temperature was controlled at 60℃~70℃, and after reacting for 11~13h, the superdispersant was obtained by rotary evaporation and applied to the dispersion of liquid disperse dyes.

[0017] The general structural formula of the hyperdispersant is specifically shown in Formula I:

[0018]

[0019] in:

[0020] D represents an acrylic monomer, such as acrylic acid or methacrylic acid; E represents a monomer containing at least one benzene ring, such as styrene, 2-vinylnaphthalene, or 4-vinylbiphenyl; this carbon chain has a hydrophobic end, anchoring the dye particles; Q represents a hydrophilic polymer, such as polyethylene glycol or polyvinyl alcohol, with a hydrophilic end. The resulting solvated chain creates steric hindrance between dye particles, effectively preventing their aggregation. Where x is an integer from 1 to 4, y is an integer from 1 to 12, and z is an integer from 1 to 5.

[0021] In step (1), the synthesis of the superdispersant specifically includes:

[0022] (1.1) Weigh RAFT reagent, maleic anhydride and initiator and dissolve them in a certain amount of dipropylene glycol dimethyl ether and place them in the reactor. Then weigh acrylic acid and 2-vinylnaphthalene monomers and catalyst and dissolve them in dipropylene glycol dimethyl ether and add them dropwise to the reactor. Control the dropping time to 2-6 hours. Before the reaction, purge the reactor with nitrogen to remove oxygen from the reactor.

[0023] (1.2) After reacting at 75℃~85℃ for 2.5~3.5h, the product is washed with toluene and dried in a vacuum oven to obtain a white powder, which is a macromolecular copolymer.

[0024] In step (1.1), the solvent is dipropylene glycol dimethyl ether, the monomer containing at least one benzene ring is 2-vinylnaphthalene, the acrylic acid and 2-vinylnaphthalene monomers and the catalyst are dissolved in dipropylene glycol dimethyl ether and added dropwise to the reactor at a time controlled to be 2-6 h, and the reaction conditions are a water bath temperature of 75℃-85℃ for 2.5-3.5 h.

[0025] In step (1.1), the molar ratio of the three monomers 2-vinylnaphthalene, acrylic acid, and maleic anhydride is 10-30:20-40:30-50.

[0026] In step (1.1), the initiator is azobisisobutyronitrile (AIBN), and its addition amount is 1% to 4% of the total mass of the monomers (2-vinylnaphthalene, acrylic acid, and maleic anhydride), more preferably 3%.

[0027] The catalyst is benzoyl peroxide, and its addition amount is 2% to 5% of the total mass of the monomers (2-vinylnaphthalene, acrylic acid, and maleic anhydride), which is further optimized to 3%.

[0028] The RAFT reagent is butyl-(1-phenylethyl) trithiocarbonate, which accounts for 60 to 120 parts per million of the total mass of the monomers (2-vinylnaphthalene, acrylic acid, and maleic anhydride), i.e., 60 to 120 ppm.

[0029] In step (1.2), the obtained product is washed three times with toluene and then dried in a vacuum oven for 4 to 6 hours.

[0030] The synthetic route of the copolymer obtained in step (1) is as follows:

[0031]

[0032] In step (2), the degree of polymerization of the polyethylene glycol is 200 to 800, and the catalyst is p-toluenesulfonic acid, which is used in an amount of 2% to 5% of the total mass of the macromolecular copolymer and polyethylene glycol.

[0033] In step (2), the temperature during the rotary evaporation process should be controlled at 30-35℃. The rotation speed during rotary evaporation should be gradually increased from slow to fast. When the rotation speed reaches 80-100 rpm, the rotation speed should be stabilized until the solution no longer loses any mass.

[0034] The synthetic route of the hyperdispersant obtained in step (2) is as follows:

[0035]

[0036]

[0037] The application of the superdispersant for liquid disperse dyes specifically includes: weighing disperse dye filter cake, superdispersant and water, mixing them, adding zirconia beads, transferring to a grinder and grinding for 2-5 hours to obtain liquid disperse dye.

[0038] The application of the superdispersant for liquid disperse dyes specifically includes: using Disperse Red 60 filter cake (20g), with the superdispersant accounting for 30%–50% of the filter cake's weight, then adding deionized water to bring the total to 150g, and grinding using a high-throughput tissue homogenizer. The zirconium oxide beads have a diameter of 0.6–2mm, and the homogenizer speed is 1500–2100 r / min. More preferably, the beads are 1.2mm in diameter, and the homogenizer speed is 1500–2100 r / min, more preferably 1800 r / min. The grinding time is further optimized to 4 hours.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] I. The superdispersant of this invention uses 2-vinylnaphthalene as a hydrophobic monomer, which can form an anchor on disperse dye particles and has a strong affinity for disperse dyes. Polyethylene glycol, as a hydrophilic group, can provide steric hindrance, preventing aggregation between dye particles, thereby achieving good stability.

[0041] Second, the superdispersant of the present invention has higher grinding efficiency when preparing liquid dispersed dyes, and the prepared liquid dispersed dyes have good storage stability.

[0042] Third, the superdispersant of this invention is prepared through RAFT polymerization. RAFT polymerization allows for the control of the molecular weight of the superdispersant. By comparing the dispersion effects of superdispersants with different molecular weights on liquid dispersed dyes, the superdispersant with the best dispersion effect can be obtained. Furthermore, RAFT polymerization allows for the control of the superdispersant structure. By comparing random, block, and gradient block structures, dispersants with even better dispersion effects can be obtained. This is a significant advantage of this invention compared to traditional polymeric dispersants. Attached Figure Description

[0043] Figure 1 This is the synthetic route for 2-vinylnaphthalene-acrylic acid-maleic anhydride copolymer.

[0044] Figure 2 This is the synthetic route for the superdispersant used in Examples 1-16.

[0045] Figure 3 It is the superdispersant used in Examples 1-16. 1 H-NMR spectrum.

[0046] Figure 4 The particle size distributions are those of liquid dispersed dyes (i.e., Examples 1-7) obtained by dispersing with different amounts of RAFT reagent as a superdispersant.

[0047] Figure 5It represents the conformations of three structures: random copolymerization, block copolymerization, and gradient copolymerization of superdispersants.

[0048] Figure 6 The random copolymer adopts a shrinkage conformation with the hydrophobic end facing the outside of the air / water interface and its main chain parallel to the air / water interface;

[0049] Figure 7 Extend the backbone of the block copolymer to make it perpendicular to the air / water interface;

[0050] Figure 8 Gradient copolymerization has both parallel and perpendicular interfaces to the air / water interface. Detailed Implementation

[0051] The present invention will be further described below with reference to the accompanying drawings and embodiments. It should be specifically noted that the embodiments are only for the purpose of helping to understand the present invention, and do not limit the scope of the present invention. The technical features involved in the various embodiments can be combined with each other without conflict.

[0052] RAFT polymerization allows for the preparation of hyperdispersants, enabling control over both molecular weight and structure. The regulation of hyperdispersant structure includes random copolymerization, block copolymerization, and gradient copolymerization. The conformations of these three structures are as follows: Figure 5 As shown. Random copolymers may adopt a shrinkage conformation, with the hydrophobic end facing outwards from the air / water interface and its backbone parallel to the air / water interface, such as... Figure 6 As shown; block copolymers can extend the main chain to be perpendicular to the air / water interface, such as... Figure 7 As shown; gradient copolymerization occurs both parallel to and perpendicular to the air / water interface, such as... Figure 8 As shown.

[0053] A method for synthesizing a hyperdispersant for preparing liquid disperse dyes via RAFT polymerization includes the following steps:

[0054] (1) Weigh out RAFT reagent butyl-(1-phenylethyl) trithiocarbonate, maleic anhydride, and initiator, dissolve them in dipropylene glycol dimethyl ether, and place them in a reactor. Then weigh out acrylic acid and 2-vinylnaphthalene monomers, and catalyst benzoyl peroxide, dissolve them in dipropylene glycol dimethyl ether, and add them dropwise to the reactor. Control the dropwise addition time to 4 hours. Before the reaction, purge the reactor with nitrogen to remove oxygen. After the dropwise addition, react at 80°C for 3 hours, wash three times with toluene, and dry in a vacuum oven for 5 hours to obtain a white powder, which is the macromolecular copolymer.

[0055] (2) The obtained macromolecular copolymer and polyethylene glycol (degree of polymerization 600) were dissolved in acetone, and then p-toluenesulfonic acid catalyst was added to react. The amount of p-toluenesulfonic acid was 3% of the total mass of the macromolecular copolymer and polyethylene glycol. The reaction temperature was controlled at 65℃, and the polymeric dispersant was obtained by rotary evaporation after 12 h of reaction.

[0056] The synthetic route of the copolymer obtained in step (1) is as follows:

[0057]

[0058] The synthetic route of the hyperdispersant obtained in step (2) is as follows:

[0059]

[0060] In step (1), the molar ratio of the three monomers 2-vinylnaphthalene, acrylic acid, and maleic anhydride is 2:3:5.

[0061] Nitrogen gas was introduced into the reactor for 20 minutes before the reaction to remove oxygen.

[0062] In step (1), the initiator is azobisisobutyronitrile (AIBN), and its addition amount is 3% of the total mass of the monomers (2-vinylnaphthalene, acrylic acid, and maleic anhydride); the catalyst is benzoyl peroxide, and its addition amount is 3% of the total mass of the monomers (2-vinylnaphthalene, acrylic acid, and maleic anhydride); the RAFT reagent is butyl-(1-phenylethyl) trithiocarbonate, which accounts for 60 to 120 parts per million of the total mass of the monomers (2-vinylnaphthalene, acrylic acid, and maleic anhydride), i.e., 60 to 120 ppm.

[0063] Using superdispersants in the preparation of liquid dispersed dyes, specifically including:

[0064] Weigh out the disperse dye filter cake, superdispersant and water, mix them, add zirconia beads, transfer to a grinder and grind to obtain liquid disperse dye.

[0065] The disperse dye filter cake used is Disperse Red 60 filter cake, with a cake weight of 20g. The superdispersant accounts for 30% to 50% of the cake weight, and then deionized water is added to make up to 150g. The cake is then ground using a high-throughput tissue homogenizer, with zirconia beads having a diameter of 0.6 to 2.0 mm. The high-throughput tissue homogenizer rotates at 1500 to 2100 r / min, and the grinding time is 2 to 5 hours.

[0066] The specific conditions for the embodiments can be found in Table 1:

[0067] Table 1

[0068]

[0069] The dyes provided in Examples 1-16 and the comparative examples were subjected to particle size and stability tests, and the results are shown in Table 2.

[0070] Table 2: Dispersibility and stability tests of liquid disperse dyes

[0071] Example Particle size (nm) PDI Stability (days) Comparative Example 259.6 0.263 50～70 Example 1 220.5 0.173 80～100 Example 2 192.7 0.160 80～100 Example 3 168.6 0.182 90～110 Example 4 152.3 0.152 90～110 Example 5 159.6 0.179 90～110 Example 6 171.3 0.185 80～100 Example 7 179.2 0.192 80～100 Example 8 162.9 0.201 80～100 Example 9 182.3 0.185 90～110 Example 10 190.6 0.216 80～100 Example 11 180.1 0.180 80～100 Example 12 172.6 0.195 90～110 Example 13 192.6 0.201 80～100 Example 14 175.3 0.149 80～100 Example 15 193.2 0.226 80～100 Example 16 160.2 0.163 90～110

[0072] Table 1 shows that the particle size of the liquid disperse dyes in Examples 1-16 is smaller than that of the comparative example, indicating that the dispersibility of the liquid disperse dyes in Examples 1-16 is better than that of the comparative example. In Examples 1-7, the molecular weight of the superdispersant decreases with increasing RAFT reagent dosage. The reason why the dispersion performance of the liquid disperse dyes in Examples 1-4 is better with decreasing superdispersant molecular weight may be because the dispersant forms more anchorage on the surface of the disperse dye particles, allowing for better dye dispersion. The reason why the dispersion performance of the liquid disperse dyes in Examples 4-7 is worse with decreasing superdispersant molecular weight may be because the chain length of the hydrophilic groups is shorter with decreasing superdispersant molecular weight, weakening the steric hindrance effect between dye particles and making it easier for dye particles to aggregate, thus worsening the dispersibility of the dye. Examples 8-10, 11 and 12, 13 and 14, and 15 and 16 observed the effects of zirconium bead diameter, dispersant dosage, grinding speed, and grinding time on the liquid disperse dyes.

[0073] Figure 1 , Figure 2 A synthetic process for preparing a superdispersant for liquid disperse dyes via RAFT polymerization, wherein... Figure 1 The synthesis process of the superdispersant anchoring component. Figure 2 This is a process of anchoring and solvating the chain. Through Examples 1-7, we determined that a superdispersant with a molecular weight of 5500 exhibits the best dispersion effect, and we characterized the superdispersant with a molecular weight of 5500. Figure 3 That is its 1 ¹H NMR spectra. During the synthesis of superdispersants, different amounts of RAFT reagent result in different molecular weights of the superdispersants, leading to variations in dispersion effects. Ultimately, this manifests as differences in the dispersed dye particle size, such as... Figure 4 As shown.

Claims

1. The application of hyperdispersants for liquid disperse dyes in the preparation of liquid disperse dyes, characterized in that, Specifically, it includes: Weigh the disperse dye filter cake, mix the liquid disperse dye with superdispersant and water, add zirconia beads, transfer to a grinder and grind for 2-5 hours to obtain the liquid disperse dye; The preparation of the superdispersant for liquid disperse dyes specifically includes: (1) A macromolecular copolymer with a weight average molecular weight of 1,000-30,000 g / mol was synthesized by RAFT free radical polymerization-induced self-assembly of butyl-(1-phenylethyl) trithiocarbonate using RAFT reagent; The synthesis of macromolecular copolymers specifically includes: (1.1) Weigh RAFT reagent butyl-(1-phenylethyl) trithiocarbonate, initiator and maleic anhydride dissolved in dipropylene glycol dimethyl ether and placed in the reactor. Weigh acrylic acid and 2-vinylnaphthalene monomers and catalyst dissolved in dipropylene glycol dimethyl ether and added dropwise to the reactor, controlling the dropping time to 2-6 h. Before the reaction, nitrogen gas is introduced into the reactor to remove oxygen from the reactor. The initiator is azobisisobutyronitrile; The catalyst is benzoyl peroxide; The molar ratio of the three monomers, 2-vinylnaphthalene, acrylic acid, and maleic anhydride, is 10~30:20~40:30~50; The amount of the RAFT reagent used is 60 to 120 parts per million of the total mass of the three monomers: 2-vinylnaphthalene, acrylic acid, and maleic anhydride. (1.2) After the addition is complete, the reaction is carried out at 75℃~85℃ for 2.5~3.5 h. After washing with toluene, the mixture is dried in a vacuum oven to obtain a white powder, which is a macromolecular copolymer. (2) Dissolve the obtained macromolecular copolymer and polyethylene glycol in acetone respectively, and finally add a catalyst to react. Control the reaction temperature at 60℃~70℃. After reacting for 11~13 h, rotary evaporate to obtain a superdispersant for liquid disperse dyes. The degree of polymerization of the polyethylene glycol is 200-800, and the catalyst is p-toluenesulfonic acid.

2. The application according to claim 1, characterized in that, In step (1.2), the product is washed three times with toluene and then dried in a vacuum oven for 4 to 6 hours.

3. The application according to claim 1, characterized in that, In step (2), the temperature during the rotary evaporation process should be controlled at 30~35℃. The rotation speed during rotary evaporation should be increased from slow to fast. When the rotation speed reaches 80~100 rpm, the rotation speed should be stabilized until the solution no longer loses any mass.

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