Preparation method and application of polymer-coated pigment ink for textile digital inkjet printing

Abstract

The application discloses a preparation method and application of a polymer-coated pigment ink for textile digital inkjet printing. The ink is prepared by taking pigment as a core, dispersing the pigment by an "active" hyperdispersant to obtain nano pigment color paste with small particle size and narrow distribution, taking copolymer as a shell, and adjusting the proportion of soft and hard monomers in the copolymer by RAFT emulsion polymerization to prepare a soft core and hard shell polymer coating layer with high film forming temperature and low glass transition temperature, and finally adding water-soluble organic solvent to adjust the obtained target pigment ink. The pigment ink is stable in performance, convenient to use, has high color fastness, comfortable fabric hand feeling, reduces the surface penetration performance of the fabric, improves the fineness of the inkjet printing pattern, has self-adhesion and universality, and can be applied to printing of various fabric substrates, greatly improves the application range of digital inkjet, has a wide application prospect in the field of textile digital inkjet printing, and is convenient for large-scale production and promotion.

Description

Technical Field

[0001] This invention relates to the field of textile printing and dyeing technology, and in particular to a method for preparing and applying a polymer-coated pigment ink for digital inkjet printing of textiles. Background Technology

[0002] Digital inkjet printing, as an advanced technology in the textile industry, is driving the industry towards a green, environmentally friendly, and pollution-free process. Digital inkjet printing eliminates the need for plate making, simplifies the process, and produces superior printing results with clear outlines and vibrant colors. It solves various problems associated with traditional printing processes, such as severe pollution, environmental mess, and large equipment footprint. It enables personalized, high-quality, multi-variety, and multi-color printing, and has broad development prospects.

[0003] Pigment ink digital printing technology features a short process, eliminating the need for energy-intensive, water-intensive, and polluting processes such as steaming, soaping, and washing. It is non-selective in its application to fabric materials, making it an energy-saving and emission-reducing textile printing process that aligns with the development trend of energy-efficient and clean production. However, the production of pigment inks is challenging, resulting in a limited number of mature pigment ink varieties on the market. Currently, most commercially available digital inkjet printing pigment inks are foreign products, including Ciba's Irgaphor series, BASF's Helizarin EVOP-100 series, DuPont's Artistri 700 series, and Trident's Fabric Fast Ultra series. Domestic companies have initially mastered key technologies such as ultra-fine pigment processing and color fixing. Their developed 6-color and 4-color pigment inks have achieved good results after trials on piezoelectric inkjet printers. Patent CN113881283A discloses a water-based pigment ink, prepared by mixing pigment paste, water-based aliphatic polyurethane resin, water-based wax emulsion, water-based organic solvent, and the remaining water. Patent CN109337445A discloses a digital printing coating ink, prepared by mixing pigments, dispersants, resins, emulsifiers, pH adjusters, humectants, surfactants, bactericides, and preservatives. Previous reports all consist of a mixture of pigment particles and binder particles, which suffers from insufficient binder targeting, low adhesion efficiency, and the problem of pigment ink forming a film at the printhead, clogging it. This results in a trade-off between achieving colorfastness, hand feel, breathability, and precision in the printed fabric, hindering its widespread application.

[0004] Therefore, there is an urgent need to develop a polymer-coated pigment ink for digital inkjet printing of textiles with high fastness, self-adhesion, and versatility, so as to promote the development of the domestic digital printing industry and realize the transformation of the production of printed products in the domestic textile industry from low-tech content to high-tech content and high-quality products. Summary of the Invention

[0005] Based on this, to address the problems of insufficient targeting of binders and pigments, low adhesion efficiency, and easy clogging of printheads by pigment inks, this invention provides a method for preparing polymer-coated pigment inks for digital inkjet printing of textiles and its application. This invention proposes the concept of pre-composite encapsulation of binders and pigments, using pigments as the core and copolymers as the shell to prepare a soft-core, hard-shell polymer-coated pigment ink with both high film-forming temperature and low glass transition temperature. The formation rules of the microphase structure and film-forming mechanism of the coating on the fabric surface were elucidated, achieving single-fiber encapsulation of pigments on the fabric surface, with coloring quality approaching or reaching the level of dye dyeing.

[0006] This invention uses water as a medium and environmentally friendly materials to prepare self-adhesive digital inkjet printing pigment inks. It employs an "active" superdispersant and, through in-situ polymerization of nanoparticles, regulates the microstructure of the film-forming polymer, enabling it to possess both high film-forming temperature and low glass transition temperature properties, thus resolving the contradiction between smooth inkjet printing and high adhesion requirements.

[0007] To achieve the above objectives, one technical solution of the present invention is:

[0008] Preparation and application of a polymer-coated pigment ink for digital inkjet printing of textiles. This invention relates to a polymer-coated pigment ink that uses a pigment as the core, dispersed by an "active" superdispersant to obtain nano-pigment paste with small particle size and narrow distribution; a copolymer as the shell, prepared by adjusting the ratio of soft and hard monomers in the copolymer through RAFT emulsion polymerization to obtain a soft-core, hard-shell polymer coating layer with both high film-forming temperature and low glass transition temperature; and finally, the target pigment ink is obtained by adding a water-soluble organic solvent.

[0009] The specific preparation steps are as follows:

[0010] (1) The pigment, “active” superdispersant, zirconium beads and water are mixed and ground for a certain time, and then the grinding liquid is placed in a cell pulverizer and sonicated to obtain organic pigment paste.

[0011] (2) The ground pigment paste, soft monomer, RAFT reagent, initiator and water are mixed and stirred to obtain a crude emulsion, and then a fine emulsion is obtained by passing it through a cell disruptor. The core layer polymer is obtained by reacting at a certain temperature and time. Then, a soft core hard shell polymer-coated pigment emulsion is obtained by injecting hard monomer and reacting for a certain time.

[0012] (3) Finally, add water-soluble organic solvent to adjust the viscosity of the polymer-coated pigment emulsion to obtain the target pigment ink.

[0013] Further preferred, the mass ratio of the pigment, "active" superdispersant, zirconium beads, and water is 1:1-2:50:100, and the grinding time is 6 hours. The ultrasonic power of the cell disruptor is 200-400W, and the ultrasonic time is 20-30 minutes to obtain the pigment paste. The particle size of the pigment paste is 70-80 nm.

[0014] Further preferably, the pigment is any one of phthalocyanine blue, magenta, permanent yellow, and carbon black.

[0015] A further preferred method for preparing the active superdispersant is as follows: a mixed solution consisting of N-vinylpyrrolidone, methoxy polyethylene glycol acrylate, anchoring group monomer, RAFT reagent, and solvent is slowly added to a reactor. An initiator is added, and the mixture is stirred at 70-80°C for 4-6 hours to obtain a crude product. Finally, hexane is added for purification, and the product is dried to obtain the "active" superdispersant.

[0016] The ratio of N-vinylpyrrolidone and methoxy polyethylene glycol acrylate, anchoring monomer, RAFT reagent, and initiator is 24:8-12:1-8, and the mass ratio of RAFT reagent to initiator is 2-5:1-3. The anchoring group is any one of styrene group, 4-vinylbiphenyl group, and 2-vinylnaphthalene group, as shown in Formula 1.

[0017]

[0018] Where x = 24, y = 8 - 12, z = 1 - 8.

[0019] Further preferred, the preparation method of the active superdispersant is as follows: a mixed solution consisting of N-vinylpyrrolidone, methoxy polyethylene glycol acrylate, anchoring group monomer, RAFT reagent, and solvent is slowly added to a reactor, followed by the addition of an initiator and stirring at 80°C for 4 hours to obtain a crude product. Finally, hexane is added for purification, and the product is dried to obtain the "active" superdispersant. The ratio of N-vinylpyrrolidone to methoxy polyethylene glycol acrylate, 4-vinylbiphenyl, RAFT reagent, and initiator is 24:10:1, and the mass ratio of RAFT reagent to initiator is 5:1. The structure is as shown in Formula 2.

[0020]

[0021] Where x = 24, y = 10, z = 1.

[0022] Further preferably, in step (2), the mass ratio of pigment paste, soft monomer, hard monomer, emulsifier, RAFT reagent, initiator, and water is 0.1-0.2:8-10:1-3:0.4-0.6:0.4-0.6:0.07-0.1:30-40. The ground pigment paste, soft monomer, emulsifier, RAFT reagent, initiator, and water are mixed and stirred for 15 minutes. The cell disruptor power is 300-400W, and the mixture is stirred for 10-20 minutes (more preferably 15 minutes) at 70-80℃ for 4-8 hours (6 hours at 70℃). Then, a soft-core, hard-shell polymer-coated pigment emulsion is obtained by injecting hard monomers and reacting for 1-3 hours (more preferably 2 hours).

[0023] Further preferably, the soft monomer in step (2) is any one of ethyl acrylate, butyl acrylate or isooctyl acrylate.

[0024] The hard monomer is any one or more of methyl methacrylate, styrene, or polydimethylsiloxane-methacrylate.

[0025] The RAFT reagent is either 4-cyano-4-(dodecylsulfonylthiocarbonyl)-sulfamylvaleric acid or S,S'-bis(R,R'-dimethyl-R”-acetic acid)-trithiocarbonate.

[0026] The emulsifier is an olefin oxysulfonate.

[0027] The initiator is azobisisobutyronitrile.

[0028] In a further preferred embodiment, the mass ratio of water-soluble organic solvent to pigment ink in step (3) is 1-2:10.

[0029] Further preferably, the water-soluble organic solvent in step (3) is any one or more of glycerol, ethylene glycol, triethylene glycol, 1,3-butanediol and N-methyl-2-pyrrolidone.

[0030] This invention applies the prepared polymer-coated pigment ink to digital inkjet printing.

[0031] The beneficial effects of this invention are:

[0032] (1) In this invention, organic pigments are anchored on the surface of pigment particles under the action of "active" dispersant, and they are stably combined together; while the hydrophilic groups of pigments can form solvation chains, causing steric hindrance between pigment particles, effectively preventing the aggregation of dye particles, and finally forming a stable pigment paste.

[0033] (2) A soap-free RAFT emulsion polymerization method was innovatively used to synthesize a soft-core, hard-shell polymer coating layer. By adjusting the ratio of soft and hard monomers, a controllable film-forming temperature and Tg range were prepared, achieving polymer microstructure control with both high film-forming temperature and low glass transition temperature.

[0034] It improves the color fastness and fineness of pigment inks for digital inkjet printing of textiles, effectively solving the problems of pigment digital printing inks.

[0035] (3) Based on the characteristics of polymer-coated pigment digital printing ink for textiles, such as self-adhesion, short process and versatility, it solves the problems of long process, selective ink for substrate and unsuitability for blended fabrics in traditional dye digital inkjet printing. Attached Figure Description

[0036] Figure 1 NVP is an "active" superdispersant. 24 -co-mPEGA 10 -co-2VP1 NMR and GPC;

[0037] Figure 2 A schematic diagram illustrating the preparation of polymer-coated pigment latex through in-situ polymerization under the regulation of "active" superdispersants;

[0038] Figure 3 The infrared image is a P(BA-co-St) image.

[0039] Figure 4 TEM images of (a) pigment and (b) polymer-coated pigment;

[0040] Figure 5 DSC diagram for an example;

[0041] Figure 6 The pattern is printed using digital inkjet printing. Detailed Implementation

[0042] The present invention will be further described below with reference to embodiments.

[0043] The following examples are intended to enable those skilled in the art to gain a more comprehensive understanding of the present invention, but do not limit the invention in any way.

[0044] Example 1

[0045] (1) Preparation of “active” superdispersant: 24 mmol N-vinylpyrrolidone, 10 mmol methoxy polyethylene glycol acrylate, 1 mmol 2-vinylnaphthalene, 0.5 g trithiocarbonate and 0.1 g initiator were added to 1,4-dioxane and stirred until homogeneous. Nitrogen gas was then introduced for 15 min, and the mixture was reacted at 80 °C for 4 h to obtain a crude product. Finally, hexane was added for purification, and the product was dried to obtain the “active” superdispersant. Figure 1 This indicates that the superdispersant was successfully prepared. GPC analysis yielded a molecular weight of 5320, and analysis showed that the x, y, z ratio was 24:10:1, confirming the superdispersant's structural formula as NVP. 24 -co-mPEGA 10 -co-2VP1. Subsequent embodiments all use NVP. 24 -co-mPEGA 10 -co-2VP1 superdispersant for dispersing pigments (Formula 2 "active" superdispersant).

[0046] Add 0.1g phthalocyanine blue pigment and 0.2g NVP 24 -co-mPEGA 10 -co-2VP1 superdispersant, 5g zirconium beads, and 10g water were mixed and ground for 6 hours. The grinding solution was then placed in a 200W cell disruptor and sonicated for 20 minutes to obtain an organic pigment paste. The pigment paste had a particle size of 70-80nm.

[0047] (2) A crude emulsion was obtained by mixing and stirring 0.1 g of ground pigment paste, 9 g of butyl acrylate, 0.5 g of 4-cyano-4-(dodecylsulfonylthiocarbonyl)-sulfavalerate RAFT reagent, 0.5 g of olefin oxysulfonate, 0.1 g of azobisisobutyronitrile, and 40 g of water for 15 min. The emulsion was then pulverized for 15 min using a 400W cell disruptor to obtain a fine emulsion. The emulsion was reacted at 70°C for 6 h to obtain a core polymer. Then, 1 g of styrene was injected and reacted for 2 h to obtain a soft-core, hard-shell polymer-coated pigment emulsion, with the structure shown below. Figure 4 As shown. The preparation process is as follows. Figure 1 As shown.

[0048] (3) Finally, add 10g of glycerol to adjust the viscosity of the polymer-coated pigment emulsion to obtain the target pigment ink.

[0049] The target pigment ink obtained in Example 1 is as follows: Figure 2 and Figure 3 As shown, transmission electron microscopy reveals that the surface of phthalocyanine blue is coated with a polymer layer, and infrared spectroscopy detects the characteristic peaks of styrene and butyl acrylate, indicating that the polymer successfully coated phthalocyanine blue.

[0050] The prepared polymer-coated pigment ink has a maximum particle size of 189 nm, a viscosity of 3.2 mPa·s, a surface tension of 45 mN / m, an electrical conductivity of <5 ms / cm, a pH of 7-8, a minimum film-forming temperature of 45℃, and a glass transition temperature of 0℃.

[0051] Example 2

[0052] (1) Add 0.1g phthalocyanine blue pigment and 0.2g NVP 24 -co-mPEGA 10-co-2VP1, 5g zirconium beads and 10g water were mixed and ground for 6 hours. Then the grinding solution was placed in a 200W cell disruptor and sonicated for 20 minutes to obtain organic pigment paste.

[0053] (2) The ground pigment paste, 8g butyl acrylate, 0.5g 4-cyano-4-(dodecylsulfonylthiocarbonyl)-sulfamylvaleric acid RAFT reagent, 0.5g olefin oxysulfonate, 0.1g azobisisobutyronitrile and 40g water were mixed and stirred for 15min to obtain a crude emulsion. The emulsion was then pulverized for 15min using a 400W cell disruptor to obtain a fine emulsion. The emulsion was reacted at 70℃ for 6h to obtain a core polymer. The emulsion was then reacted for 2h by injecting 2g styrene to obtain a soft-core hard-shell polymer-coated pigment emulsion.

[0054] (3) Finally, add 10g of glycerol to adjust the viscosity of the polymer-coated pigment emulsion to obtain the target pigment ink.

[0055] The prepared polymer-coated pigment ink has a maximum particle size of 204 nm, a viscosity of 3.5 mPa·s, a surface tension of 41 mN / m, a conductivity of <5 ms / cm, a pH of 7-8, a minimum film-forming temperature of 54℃, and a glass transition temperature of 5.2℃.

[0056] Example 3

[0057] (1) Add 0.1g of phthalocyanine blue pigment of different color systems and 0.2g of NVP 24 -co-mPEGA 10 -co-2VP1 superdispersant, 5g zirconium beads and 10g water were mixed and ground for 6 hours. Then the grinding solution was placed in a 200W cell disruptor and sonicated for 20 minutes to obtain organic pigment paste.

[0058] (2) The ground pigment paste, 8g butyl acrylate, 0.5g 4-cyano-4-(dodecylsulfonylthiocarbonyl)-sulfamylvaleric acid RAFT reagent, 0.5g olefin oxysulfonate, 0.1g azobisisobutyronitrile and 40g water were mixed and stirred for 15min to obtain a crude emulsion. Then, the emulsion was pulverized for 15min using a 400W cell disruptor to obtain a fine emulsion. The emulsion was reacted at 70℃ for 6h to obtain a core polymer. Then, the emulsion was reacted for 2h by injecting 1.5g styrene and 0.5g polydimethylsiloxane-methacrylate to obtain a soft-core hard-shell polymer-coated pigment emulsion.

[0059] (3) Finally, add 10g of glycerol to adjust the viscosity of the polymer-coated pigment emulsion to obtain the target pigment ink.

[0060] The prepared polymer-coated pigment ink has a maximum particle size of 230 nm, a viscosity of 4.6 mPa·s, a surface tension of 34 mN / m, an electrical conductivity of <5 ms / cm, a pH of 7-8, a minimum film-forming temperature of 55℃, and a glass transition temperature of 8.2℃.

[0061] Example 4

[0062] (1) Add 0.1g of phthalocyanine blue pigment of different color systems and 0.2g of NVP 24 -co-mPEGA 10 -co-2VP1 superdispersant, 5g zirconium beads and 10g water were mixed and ground for 6 hours. Then the grinding solution was placed in a 200W cell disruptor and sonicated for 20 minutes to obtain organic pigment paste.

[0063] (2) The ground pigment paste, 8g butyl acrylate, 0.5g 4-cyano-4-(dodecylsulfonylthiocarbonyl)-sulfamylvaleric acid RAFT reagent, 0.5g olefin oxysulfonate, 0.1g azobisisobutyronitrile and 40g water were mixed and stirred for 15min to obtain a crude emulsion. Then, the emulsion was pulverized for 15min using a 400W cell disruptor to obtain a fine emulsion. The emulsion was reacted at 70℃ for 6h to obtain a core polymer. Then, the emulsion was reacted for 2h by injecting 1g styrene and 1g polydimethylsiloxane-methacrylate to obtain a soft-core hard-shell polymer-coated pigment emulsion.

[0064] (3) Finally, add 10g of glycerol to adjust the viscosity of the polymer-coated pigment emulsion to obtain the target pigment ink.

[0065] The prepared polymer-coated pigment ink has a maximum particle size of 286 nm, a viscosity of 5.1 mPa·s, a surface tension of 31 mN / m, a conductivity of <5 ms / cm, a pH of 7-8, a minimum film-forming temperature of 60℃, and a glass transition temperature of 17.1℃.

[0066] Example 5

[0067] (1) Add 0.1g of phthalocyanine blue pigment of different color systems and 0.2g of NVP 24 -co-mPEGA 10 -co-2VP1 superdispersant, 5g zirconium beads and 10g water were mixed and ground for 6 hours. Then the grinding solution was placed in a 200W cell disruptor and sonicated for 20 minutes to obtain organic pigment paste.

[0068] (2) The ground pigment paste, 8g butyl acrylate, 0.5g 4-cyano-4-(dodecylsulfonylthiocarbonyl)-sulfamylvaleric acid RAFT reagent, 0.5g olefin oxysulfonate, 0.1g azobisisobutyronitrile and 40g water were mixed and stirred for 15min to obtain a crude emulsion. Then, the emulsion was pulverized for 15min using a 400W cell disruptor to obtain a fine emulsion. The emulsion was reacted at 70℃ for 6h to obtain a core polymer. Then, 2g polydimethylsiloxane-methacrylate was injected and reacted for 2h to obtain a soft-core hard-shell polymer-coated pigment emulsion.

[0069] (3) Finally, add 10g of glycerol to adjust the viscosity of the polymer-coated pigment emulsion to obtain the target pigment ink.

[0070] The prepared polymer-coated pigment ink has a maximum particle size of 340 nm, a viscosity of 10 mPa·s, a surface tension of 24 mN / m, an electrical conductivity of <5 ms / cm, a pH of 7-8, a minimum film-forming temperature of 65℃, and a glass transition temperature of 24.2℃.

[0071] Control group 1

[0072] The BASF pigment inks available on the market have a maximum particle size of 300 nm, a viscosity of 3 mPa.s, a surface tension of 36 mN / m, a conductivity of <5 mS / cm, a minimum film-forming temperature of 50 °C, and a glass transition temperature of 5.2 °C.

[0073] Generally, pigment inks require a maximum particle size of less than 500 nm, maintaining or minimally changing particle size under high shear (e.g., agitation, high-speed passage through a nozzle) and at different temperatures; a viscosity of 2-10 mPa·s; and a surface tension range of 30-50 mN / m. The surface tension of pigment inks not only determines droplet formation but also affects droplet wetting and penetration into fabrics. The quality of droplet formation is influenced by surface tension. Excessive surface tension makes it difficult for the ink to form small droplets, potentially resulting in longer breakage lengths or "tail-like" droplets, and also makes it difficult to wet the nozzle surface. Insufficient surface tension leads to unstable droplets, even forming "satellite-shaped" sputtering points, affecting pattern quality. The electrical conductivity of pigment inks should be less than 1 μS / cm. The minimum film-forming temperature must be greater than 50°C, and the glass transition temperature less than 25°C; otherwise, the pigment ink is prone to film formation, causing nozzle clogging.

[0074] Control group 2

[0075] (1) Add 0.1g phthalocyanine blue pigment and 0.2g NVP 24 -co-mPEGA 10 -co-2VP1, 5g zirconium beads and 10g water were mixed and ground for 6 hours. Then the grinding solution was placed in a 200W cell disruptor and sonicated for 20 minutes to obtain organic pigment paste.

[0076] (2) The ground pigment paste, 8g butyl acrylate, 0.5g 4-cyano-4-(dodecylsulfonylthiocarbonyl)-sulfamylvaleric acid RAFT reagent, 0.5g olefin oxysulfonate, 0.1g azobisisobutyronitrile and 40g water were mixed and stirred for 15min to obtain a crude emulsion. Then, the emulsion was pulverized for 15min using a 400W cell disruptor to obtain a fine emulsion. The emulsion was reacted at 70℃ for 6h to obtain a core polymer. Then, the emulsion was reacted for 2h by injecting 1.5g styrene and 0.5g polydimethylsiloxane-methacrylate to obtain a soft-core hard-shell polymer-coated pigment emulsion.

[0077] (3) Finally, add 10g of glycerol to adjust the viscosity of the polymer-coated pigment emulsion to obtain the target pigment ink.

[0078] The prepared polymer-coated pigment ink has a maximum particle size of 436 nm, poor dispersibility, and gelation.

[0079] The preferred embodiment 3 above features a pigment ink with a particle size that conforms to the inkjet printhead specifications. It is inexpensive, performs excellently, and produces sharp, clear text with minimal fuzz and smooth printing without clogging the printhead. The ink's glass transition temperature is as follows: Figure 5 The printed patterns exhibit high durability, as shown in Table 1. The patterns are as follows... Figure 6 As shown. The pigment ink of this invention is also suitable for magenta, permanent orange, and carbon black, etc., and is inexpensive and has excellent performance.

[0080] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0081] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

[0082] Table 1. Color fastness and stability of the ink in this invention.

[0083] sample Dry rubbing fastness (grade) Wet rubbing fastness (grade) stability Example 1 4 2-3 Stable and not prone to stratification Example 2 4-5 3 Stable and not prone to stratification Example 3 5 3-4 Stable and not prone to stratification Example 4 5 3-4 Stable and not prone to stratification Example 5 5 3-4 Stable and not prone to stratification Control group 1 5 3-4 Stable and not prone to stratification

Claims

1. A method for preparing a polymer-coated pigment ink for digital inkjet printing of textiles, characterized in that, Includes the following steps: (1) The pigment, active superdispersant, zirconium beads and water are mixed and ground, and then the grinding liquid is placed in a cell disruptor and sonicated to obtain organic pigment paste; The active hyperdispersant described herein has the structure of Formula 1: ； ； Formula 1; The mass ratio of the pigment, active superdispersant, zirconium beads and water is 1:1-2:50:50-100; (2) Mix organic pigment paste, soft monomer, RAFT reagent, emulsifier, initiator and water to obtain a crude emulsion, then use a cell disruptor to obtain a fine emulsion, react to obtain a core polymer, and then use an injection hard monomer to obtain a soft core hard shell polymer-coated pigment emulsion. The soft monomer is any one of ethyl acrylate, butyl acrylate, isooctyl acrylate, and lauryl acrylate; The hard monomer is any one or more of methyl methacrylate, styrene, acrylonitrile, acrylamide, and polydimethylsiloxane-methyl methacrylate; The RAFT reagent is 4-cyano-4-(((dodecylthio)thiocarbonyl)thio)valerate; The emulsifier is any one or more of olefin oxysulfonate, sodium dodecyl sulfonate, and octylphenol polyoxyethylene ether-10; The initiator is either azobisisobutyronitrile or potassium persulfate. The organic pigment paste, soft monomer, hard monomer, RAFT reagent, emulsifier, initiator, and water are present in a mass ratio of 0.1-0.2:7-10:1-4:0.4-0.6:0.4-0.6:0.07-0.1:30-40. (3) Finally, add water-soluble organic solvent to adjust the viscosity of the soft-core hard-shell polymer-coated pigment emulsion to obtain polymer-coated pigment ink for digital inkjet printing of textiles.

2. The method for preparing polymer-coated pigment ink for digital inkjet printing of textiles according to claim 1, characterized in that, In step (1), the grinding time is 5-8 h; the grinding is carried out using a cell disruptor with an ultrasonic power of 200-400 W and an ultrasonic time of 10-30 min; The organic pigment paste has a particle size of 70-80 nm.

3. The method for preparing polymer-coated pigment ink for digital inkjet printing of textiles according to claim 1, characterized in that, In step (1), the pigment is any one of phthalocyanine blue, magenta, permanent yellow and carbon black.

4. The method for preparing polymer-coated pigment ink for digital inkjet printing of textiles according to claim 1, characterized in that, In step (2), organic pigment paste, soft monomer, RAFT reagent, emulsifier, initiator and water are mixed and stirred for 10-20 minutes to obtain crude emulsion; The cell disruptor has an operating power of 300-400 W and a running time of 10-20 minutes; The core polymer was obtained by reacting at 70-80 ℃ for 4-8 h. Then, a soft-core, hard-shell polymer-coated pigment emulsion is obtained by injecting hard monomers and reacting for 1-3 hours.

5. The method for preparing polymer-coated pigment ink for digital inkjet printing of textiles according to claim 1, characterized in that, In step (3), the mass ratio of the water-soluble organic solvent to the soft-core hard-shell polymer-coated pigment emulsion is 1-2:10; The water-soluble organic solvent is any one or more of glycerol, ethylene glycol, propylene glycol, isopropanol, diethylene glycol, triethylene glycol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, and N-methyl-2-pyrrolidone.

6. The application of the polymer-coated pigment ink for digital inkjet printing of textiles prepared by the preparation method according to any one of claims 1 to 5 in digital inkjet printing.

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