Water-based environment-friendly mutual exclusion printing ink

Abstract

The invention relates to the field of water-based environment-friendly ink, and discloses water-based environment-friendly mutual exclusion ink which comprises the following components: water-based polyurethane-acrylic hybrid resin; a nanocellulose crystal; modifying the plant polyphenol pigment; and gamma-valerolactone; a polyglycerol ester surfactant; a pH response type microcapsule; the invention further provides a preparation method of the water-based environment-friendly mutual-exclusion ink. The preparation method comprises the following steps: S1, preparing the nanocellulose crystal; s2, plant polyphenol pigment modification; s3, preparing a pH response type microcapsule; s4, synthesizing waterborne polyurethane-acrylic acid hybrid resin; and S5, constructing an ink system. According to the invention, a dynamic crosslinking technology of the waterborne polyurethane-acrylic hybrid resin is adopted, so that the flexibility and durability of the ink after coating are remarkably improved, the ink has better recovery capability and stronger mechanical properties, breakage or falling of the ink under stress is avoided, and the service life of the ink is prolonged.

Description

Technical Field

[0001] The present invention relates to the field of water-based environmentally friendly inks, in particular to water-based environmentally friendly mutually exclusive inks. Background Art

[0002] In daily life, water-based inks are widely used in printing, packaging, advertising, and other fields. Especially in today's increasingly stringent environmental regulations, water-based inks have become a popular alternative to traditional solvent-based inks. Water-based inks not only effectively reduce harmful gas emissions but also minimize environmental pollution by lowering volatile organic compound (VOC) levels. Therefore, with increasing environmental awareness, the development of water-based inks with greater stability and superior performance has become increasingly important.

[0003] In the prior art, water-based inks are usually composed of water-based polyurethane, acrylic resin, plant pigments, etc., and are prepared by mechanical stirring and high-shear dispersion technology. The water-based inks of the prior art have certain environmental advantages, can effectively reduce the emission of harmful substances, and have good adhesion and cohesion. In terms of pigments, plant pigments have become a hot topic of research due to their environmental friendliness and natural origin. Some ink formulas in the prior art also use plant polyphenol pigments, but these formulas usually face the problem of poor color stability. Despite this, the performance of traditional water-based inks meets daily needs to a certain extent, and has shown certain advantages in terms of low volatility and environmental friendliness.

[0004] However, the water-based inks of the prior art still have many problems in practical applications, especially in terms of the durability, color stability, dispersibility and responsiveness of the inks. First, the existing resins often lack sufficient dynamic cross-linking structure, which makes the inks prone to breakage or fading after long-term use. Secondly, although plant pigments have the advantage of being natural and environmentally friendly, their color stability under ultraviolet light and high temperature environments is poor and they are prone to fading, affecting the long-term effectiveness of the inks. In terms of dispersibility, the dispersion technology of traditional inks usually relies on relatively simple mechanical stirring, which makes it difficult to effectively avoid the agglomeration of nano-scale materials, affecting the uniformity and stability of the inks. In addition, the existing inks cannot adaptively adjust the color when the environment changes, especially when the pH value changes, and lack responsiveness, which makes the functionality of the inks not fully utilized. To this end, those skilled in the art have proposed a water-based environmentally friendly mutually exclusive ink to solve the above problems. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the present invention provides a water-based environmentally friendly mutually exclusive ink, which solves the problems of the ink in the existing technology in terms of durability, color stability, dispersibility and environmental responsiveness.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: a water-based environmentally friendly mutually exclusive ink, comprising the following components in parts by weight: Waterborne polyurethane-acrylic acid hybrid resin: 18-25 parts; Nanocellulose crystals: 3-5 parts; Modified plant polyphenol pigment: 15-22 parts; γ-valerolactone: 10-15 parts; Polyglycerol ester surfactant: 2-4 parts; pH-responsive microcapsules: 5-8 parts.

[0007] The core of this technical solution lies in the construction of a composite system with dynamic response capabilities and mutually exclusive properties, integrating multiple functional modules such as natural polymers, metal chelate pigments, and structured microcapsules. Through the synergistic effect of these multiple components, the ink is endowed with excellent interface configuration control and reversible functional switching performance while ensuring the system is environmentally friendly.

[0008] Waterborne polyurethane-acrylic hybrid resin serves as the main film-forming material, not only providing basic film-forming and mechanical stability, but also introducing designable reactive groups and molecular network structures through hybridization strategies, giving it good interface adaptability. Nanocellulose crystals serve as bio-based reinforcing materials, forming a highly dispersed three-dimensional network skeleton in the aqueous phase, effectively improving the thixotropy and internal structural stability of the ink.

[0009] Modified plant polyphenol pigments enhance their interaction with the resin matrix through metal chelation, stabilizing their distribution while enhancing color change characteristics in response to external environmental stimuli (such as pH). γ-Valerolactone, a low-toxic solvent and synergistic diffusion aid, improves the compatibility and migration properties between components in the system, thereby regulating the drying rate and film-forming quality. Polyglycerol ester surfactants, with their excellent wettability and interfacial activity, promote uniform spreading and adsorption between the ink and the substrate.

[0010] The pH-responsive microcapsules act as functional response carriers, controlling the release behavior through the wall material and combining the reversible coordination structure of the pigment and metal ions to give the ink a controllable color development mechanism. Overall, the system has constructed a highly integrated, multifunctional, and environmentally friendly water-based ink platform through structure-performance collaborative design, which has comprehensive characteristics such as adaptability, mutual exclusion, and strong responsiveness.

[0011] Preferably, the waterborne polyurethane-acrylic hybrid resin comprises: A prepolymer formed by the reaction of isophorone diisocyanate and hydroxyethyl acrylate; The content of dynamic disulfide bonds in the prepolymer accounts for 0.5-1.5% of the total mass of the waterborne polyurethane-acrylic hybrid resin; The surface amino concentration of the waterborne polyurethane-acrylic acid hybrid resin is 2.0-2.2 mmol / m 2 , the internal amino concentration is 0.7-0.9mmol / m 2 .

[0012] In this technical solution, the waterborne polyurethane-acrylic hybrid resin achieves an organic combination of flexibility and reactivity by introducing a prepolymer generated by the reaction of isophorone diisocyanate and hydroxyethyl acrylate. Among them, isophorone diisocyanate, as a branched structural unit, can significantly improve the structural stability and chemical resistance of the system, while the introduction of hydroxyethyl acrylate gives the system adjustable polarity and hydrophilicity, improving compatibility with other water-based components.

[0013] The embedding of dynamic disulfide bonds is one of the important innovations of this invention. It has the ability of reversible breakage and recombination, which allows the resin to undergo molecular-level rearrangement when subjected to stress or environmental stimulation, resulting in self-repair or responsive behavior of the material. This strategy based on dynamic covalent chemistry is significantly different from the single linear structure of traditional water-based resins, and constructs a network with intrinsic structural evolution capabilities.

[0014] Furthermore, the gradient design between the surface and internal amino group concentrations further enhances the fine-tuning of interface construction. The high concentration of amino groups on the surface helps enhance electrostatic or hydrogen bonding with microcapsules and nanocrystals, while the relatively low concentration inside reduces heterogeneous aggregation caused by excess reactivity. This gradient distribution gives the material a high component capacity and system stability.

[0015] Preferably, the modified plant polyphenol pigment comprises: A complex is formed by a chelation reaction between tea polyphenols and iron ions, wherein the molar ratio of iron ions to polyphenols is 1:2.8-3.2.

[0016] This technical solution is based on the chelation reaction of natural tea polyphenols with metal ions to produce plant polyphenol pigments. The core of the technology is to use phenolic hydroxyl groups to react with Fe 3+ The coordination effect between ions builds a stable chelate complex structure in which Fe 3 + The ions act as bridging centers to form multi-site coordination with multiple tea polyphenol molecules, making the pigment molecules exhibit higher stability and controllable response performance.

[0017] This type of metal chelate complex has pH-responsive properties. Under different acidic and alkaline conditions, its chelated state can undergo reversible structural changes, thereby causing changes in hue or differences in color development. This property enables it to not only participate in color development as a color source in the ink system, but also to form a "switch-type" color response module in combination with the microcapsule system.

[0018] In addition, the polyphenolic hydroxyl groups in tea polyphenols can form non-covalent interactions with amino or carboxyl groups in the resin system, such as hydrogen bonds or π-π stacking, thereby improving their dispersion stability in aqueous systems. This multiple interaction ensures their effective distribution in the ink and enhances the overall response synergy of the system.

[0019] Preferably, the pH-responsive microcapsules include: A wall material formed by compounding graphene oxide and chitosan in a mass ratio of 1:2.8-3.2; The tannic acid and iron ion chelate is encapsulated in the wall material, wherein the molar ratio of the tannic acid to the iron ion is 1:2.9-3.1.

[0020] In this technical solution, pH-responsive microcapsules are used as functional release units. The core design is based on the layer-by-layer self-assembly mechanism between graphene oxide and chitosan to construct the microcapsule wall material. Graphene oxide provides excellent mechanical strength and oxygen functional group surface activity, while chitosan, as a cationic polysaccharide, can form a multilayer structure with the GO layer through electrostatic interaction, thereby enhancing the overall encapsulation and wall material density.

[0021] This type of composite wall material has good stability and strong responsiveness in an aqueous environment. It can swell, disintegrate or rearrange its structure under specific pH conditions, thereby achieving control over the release of the internal core material. The internally encapsulated tannic acid and iron ion chelate serves as the color response core. Its structure has different coordination forms under different pH conditions, which leads to reversible changes in the appearance color. This release behavior caused by changes in the wall material structure is superimposed on the core material response, providing the ink with a unique dynamic visual regulation function.

[0022] In addition, the GO / CS composite material can also produce a synergistic effect with the resin or pigment in the ink system. Especially with the participation of hydrogen bonds and electrostatic forces, its microstructure can be embedded or adsorbed on the surface of other substrates, thereby improving the overall dispersibility and controllability of the ink. The entire microcapsule system realizes the integrated regulation of "encapsulation-release-response" functions through structural design, providing key support for the intelligent response of the mutually exclusive ink in the present invention.

[0023] A method for preparing a water-based environmentally friendly mutually exclusive ink comprises the following steps: S1, preparation of nanocellulose crystals; S2, plant polyphenol pigment modification; S3, preparation of pH-responsive microcapsules; S4, synthesis of waterborne polyurethane-acrylic hybrid resin; S5. Ink system construction.

[0024] The core design of this technical solution lies in modular steps and structural functional synergy. By independently pre-processing functional components and gradually integrating them, an ink system with hierarchical responsiveness and interfacial synergy is constructed.

[0025] Step S1 is used to prepare highly dispersed nanocellulose crystals, ensuring their stable distribution in the aqueous phase as a framework material, thereby providing spatial support and viscoelastic control for the subsequent system. The morphology of the cellulose crystals has a significant impact on the rheological behavior and dispersion stability of the entire system.

[0026] Step S2 focuses on the stabilization and modification of plant polyphenol pigments, addressing issues such as susceptibility to oxidation and uneven distribution during in-situ applications. Metal ions are introduced through chelation reactions to create a stable complex structure at the molecular level, thereby endowing the pigment with controllable responsiveness and sensitivity to environmental pH changes.

[0027] Step S3 focuses on the precise construction of microcapsule carriers, achieving interface control and effective encapsulation through multilayer self-assembly. The structurally uniform microcapsules not only ensure the controlled release of functional components but also enhance their ability to synergize with other components in the aqueous phase.

[0028] In step S4, the synthesis of waterborne polyurethane-acrylic hybrid resin combines prepolymerization reaction and dynamic cross-linking. By introducing dynamic bonds and surface modification strategies, the resin system has flexibility, adhesion and dynamic response characteristics at the same time, which is the key to building the stability of the overall system.

[0029] The S5 step realizes the integration and coordinated dispersion of various functional components. In this process, through sequential control and shear parameter setting, it ensures that the components are uniformly wrapped and compatible in space, providing a complete, stable and controllable functional performance foundation for the final ink product.

[0030] Preferably, the nanocellulose crystal preparation comprises: Mixing bamboo pulp cellulose with a sulfuric acid solution having a mass concentration of 60-65% in a mass ratio of 1:4-6; Hydrolysis treatment was performed at 40-50°C for 1.5-2.5 hours; Use a centrifuge with a speed of 7000-9000 rpm for solid-liquid separation and wash with deionized water until the pH is greater than 5.5; The nanocellulose crystals with a solid content of 7-9% were obtained by treating with an ultrasonic device at a frequency of 35-45 kHz for 25-35 minutes.

[0031] This technical solution extracts highly dispersed nanocrystals from natural cellulose through a combined path of acid hydrolysis and ultrasonic depolymerization. The controlled hydrolysis of sulfuric acid can effectively break the disordered regions in the cellulose and retain the crystalline region structure, thereby obtaining highly crystalline nanomaterials.

[0032] After the hydrolysis reaction, high-speed centrifugation is used to quickly separate the cellulose and acid solution to ensure product purity and pH neutrality. Ultrasonic treatment is a key step to further reduce the tendency of crystal agglomeration, allowing the nanocellulose to exist stably in a monodisperse state in the aqueous phase.

[0033] This step establishes a rigid network structure foundation for the entire ink system, which not only enhances the structural viscoelasticity, but also provides physical support for the subsequent dispersion and integration of pigments and microcapsules.

[0034] Preferably, the plant polyphenol pigment modification includes: Dissolve tea polyphenols in deionized water to prepare a solution with a mass concentration of 25-35%; Add ferric chloride hexahydrate at a molar ratio of iron ion to polyphenols = 1:2.8-3.2; Stir the reaction at 55-65°C for 1.8-2.2 hours; The modified pigment powder is prepared by a spray drying tower with an inlet air temperature of 180-200°C.

[0035] This technical solution utilizes the multi-point coordination reaction between tea polyphenols and iron ions to construct a complex pigment with chemical stability and pH responsiveness. The reaction conditions are controlled in a mild range to ensure that the coordination reaction proceeds fully while avoiding the oxidation or degradation of polyphenols.

[0036] The complex is converted into a powder form through spray drying technology, which not only improves storage stability but also provides a process basis for subsequent dispersion in the ink system. This step reconstructs the chemical environment of the pigment at the molecular level, giving it structure-guided response performance, providing the core driving force for subsequent color tone control in the microcapsule system or resin matrix.

[0037] Preferably, the preparation of the pH-responsive microcapsules comprises: Graphene oxide and chitosan are self-assembled layer by layer in a mass ratio of 1:2.8-3.2 for 4-6 layers; Encapsulating a chelate prepared by mixing tannic acid and iron ions in a molar ratio of 1:2.9-3.1 in the wall material; A high-pressure homogenizer is used to control the particle size of the pH-responsive microcapsules to be 250-350 nm at a pressure of 50-100 MPa.

[0038] The essence of this technical solution is to construct a responsive system with layer-by-layer control capabilities. The electrostatic self-assembly between graphene oxide and chitosan realizes the molecular-level controllable construction of the microcapsule wall layer, giving it good mechanical strength and pH-regulated release capabilities.

[0039] Core-encapsulated tannic acid-Fe 3+The complex is the core response unit of the system, and the external wall material provides it with structural shielding and external condition triggering control. Under the action of high-pressure homogenization, the system forms capsules with uniform particle size and stable structure, improving its stability in the aqueous system and the accuracy of the release response.

[0040] This structure gives the microcapsules good reversible response ability and is the key to the ink's dynamic color development and interface mutual repulsion mechanism.

[0041] Preferably, the synthesis of the waterborne polyurethane-acrylic hybrid resin includes: Isophorone diisocyanate and polytetramethylene glycol are mixed at NCO / OH=1.95-2.05:1; Add 0.4-0.6% of dibutyltin dilaurate catalyst to the total mass of the system and react at 70-80°C for 2.5-3.5 hours; A dynamic disulfide bond donor was introduced and cross-linked with hydroxyethyl acrylate at a molar ratio of 1:1.1-1.3; 0.3-0.5% of aminosilane by weight of waterborne polyurethane-acrylic hybrid resin is added to construct a surface amino gradient.

[0042] This technical solution constructs a hybrid resin skeleton through a two-stage reaction pathway, introducing dynamically adjustable molecular units into the basic structure. Isophorone diisocyanate and polyether polyol provide a flexible main chain and controllable side chains, while the subsequent cross-linking unit (dynamic disulfide bond donor) provides a stress response path.

[0043] The catalyst ensures the efficient reactivity of isocyanate, while the introduction of aminosilane is specifically used to adjust the surface functional gradient, giving the system high affinity at the interface, thereby enhancing the binding selectivity of microcapsules and pigments. This internal structure-surface performance synergistic design provides the entire ink system with dual guarantees of structural flexibility and functionality.

[0044] Preferably, the ink system construction includes: The pH-responsive microcapsules and γ-valerolactone were mixed in a weight ratio of 5-8:10-15, and ultrasonic treatment was performed with a power of 90-110 W for 10-20 minutes; After adding polyglycerol ester surfactant, use shear rate 750-1250s -1 High-speed disperser mixing; Nanocellulose crystals, waterborne polyurethane-acrylic hybrid resin, and modified plant polyphenol pigment were sequentially added, and the pH was adjusted to 7.4-8.1; After adding deionized water, filter through a 180-220 mesh sieve to obtain the final ink product.

[0045] This technical solution is a key stage in the functional integration of the components of the present invention. Through specific sequence and shear condition control, each functional component is distributed in the aqueous system in the most stable state. The pH-responsive microcapsules are first fully dispersed with γ-valerolactone, which helps to form a uniform colloidal distribution in the initial construction stage of the ink and improve the overall response consistency of the system.

[0046] The addition of surfactants not only enhances the wettability between components, but also provides interface regulation for the subsequent stable phase. High shear dispersion ensures the full disaggregation and network fusion of polymers, microcapsules, and nanoparticles, and is a key control point for the stability of the system structure. The final pH adjustment and screening steps further improve the system uniformity and processing adaptability, ensuring the quality of the finished product.

[0047] In summary, this application includes at least one of the following beneficial technical effects: 1. The present invention adopts dynamic crosslinking technology of water-based polyurethane-acrylic hybrid resin, which significantly improves the flexibility and durability of the ink after coating. Compared with traditional resins commonly used in the prior art, dynamic crosslinking gives the ink better recovery ability and stronger mechanical properties, avoids the breakage or shedding of the ink under stress, and improves the service life of the ink.

[0048] 2. The present invention imparts better color stability to the ink by modifying the chelation reaction between plant polyphenol pigments and iron ions. Compared with the prior art scheme of directly using plant pigments, the chelation technology significantly improves the color retention ability of the ink under ultraviolet light irradiation and high temperature conditions, avoids fading or failure of the pigment, and ensures the application effect of the ink in changing environments.

[0049] 3. By introducing a pH-responsive microcapsule system, the present invention enables the ink to exhibit different color rendering effects according to changes in the environmental pH value, greatly improving the functionality and interactivity of the ink. Compared with traditional inks, this innovation enables the ink to respond to changes in the external environment, expands the application scenarios of the ink, and solves the limitation of traditional inks that lack dynamic response function.

[0050] 4. The present invention uses ultrasonic treatment technology to optimize the dispersibility of nanocellulose and improve the stability and uniformity of the ink. Compared with existing conventional dispersion methods, ultrasonic treatment can effectively avoid the agglomeration of nanocellulose, making it less likely for the ink to stratify or settle during storage, thereby improving the long-term storage stability of the ink and solving the problem of easy precipitation and stratification of traditional inks. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a schematic flow chart of the preparation method of the present invention. DETAILED DESCRIPTION

[0052] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the present specification. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0053] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0054] Please see the attached Figure 1 : Example 1: Component ratio: Waterborne polyurethane-acrylic hybrid resin: 21 parts; nanocellulose crystals: 4 parts; modified plant polyphenol pigment: 18 parts; γ-valerolactone: 12 parts; polyglycerol ester surfactant: 3 parts; pH-responsive microcapsules: 6 parts.

[0055] Preparation steps: 1. Preparation of Nanocellulose Crystals: Bamboo pulp cellulose was mixed with a 63% sulfuric acid solution in a 1:5 mass ratio. The reaction temperature was controlled at 45°C and the hydrolysis treatment was carried out for 2 hours. After the reaction, solid-liquid separation was performed using a centrifuge at 8000 rpm and the product was washed with deionized water until the pH was greater than 5.5. Subsequently, an ultrasonic device with a frequency of 40 kHz was used for 30 minutes to obtain nanocellulose crystals with a solid content of 8%.

[0056] 2. Modification of plant polyphenol pigments: Tea polyphenols were dissolved in deionized water to prepare a 30% solution. Ferric chloride hexahydrate was added at a molar ratio of 1:3 iron ions to tea polyphenols. The reaction temperature was controlled at 60°C for 2 hours. After the reaction, the solution was converted into a powder in a spray dryer with an inlet air temperature of 190°C to obtain a modified plant polyphenol pigment powder.

[0057] 3. Preparation of pH-responsive microcapsules: Graphene oxide and chitosan were dissolved in deionized water at a mass ratio of 1:3, and a four-layer wall structure was formed via multilayer self-assembly. A chelate of tannic acid and iron ions was added at a molar ratio of 1:3 and encapsulated within the wall structure. The resulting structure was then homogenized in a high-pressure homogenizer at 60 MPa to produce pH-responsive microcapsules with a particle size of 300 nm.

[0058] 4. Synthesis of waterborne polyurethane-acrylic hybrid resin: Isophorone diisocyanate and polytetramethylene glycol were mixed at an NCO / OH ratio of 2:1, and 0.5% dibutyltin dilaurate catalyst was added at 80°C for 3 hours. Subsequently, a dynamic disulfide bond donor and hydroxyethyl acrylate (molar ratio of 1:1.2) were added for cross-linking. Finally, 0.4% aminosilane was added for surface modification to obtain the final waterborne polyurethane-acrylic hybrid resin.

[0059] 5. Ink system construction: The prepared pH-responsive microcapsules were mixed with γ-valerolactone at a weight ratio of 6:12 and treated with ultrasound at a power of 100 W for 10 minutes. After adding the polyglycerol ester surfactant, the microcapsules were treated with ultrasound at a shear rate of 1000 s -1 Mix in a high-speed disperser. Then, add nanocellulose crystals, water-based polyurethane-acrylic hybrid resin, and modified plant polyphenol pigment in sequence, and adjust the pH to 7.5. Finally, add deionized water and filter through a 180-mesh sieve to obtain the final water-based, environmentally friendly, mutually exclusive ink product.

[0060] Example 2: Component ratio: Waterborne polyurethane-acrylic hybrid resin: 18 parts; nanocellulose crystals: 3 parts; modified plant polyphenol pigment: 15 parts; γ-valerolactone: 10 parts; polyglycerol ester surfactant: 2 parts; pH-responsive microcapsules: 5 parts.

[0061] Preparation steps: 1. Preparation of Nanocellulose Crystals: Bamboo pulp cellulose was mixed with a 60% sulfuric acid solution in a 1:4 mass ratio. The reaction temperature was controlled at 40°C and the hydrolysis treatment was carried out for 1.5 hours. After the reaction was completed, solid-liquid separation was performed using a centrifuge at 7000 rpm and the product was washed with deionized water until the pH was greater than 5.5. Then, an ultrasonic device with a frequency of 35 kHz was used for 25 minutes to obtain nanocellulose crystals with a solid content of 7%.

[0062] 2. Modification of plant polyphenol pigments: Tea polyphenols were dissolved in deionized water to prepare a 25% solution. Ferric chloride hexahydrate was added at a molar ratio of 1:2.8 (iron ion:tea polyphenol). The reaction temperature was controlled at 55°C for 1.8 hours. After the reaction, the solution was converted into a powder in a spray dryer with an inlet air temperature of 180°C to obtain a modified plant polyphenol pigment powder.

[0063] 3. Preparation of pH-responsive microcapsules: Graphene oxide and chitosan were dissolved in deionized water at a mass ratio of 1:3, and the microcapsule wall material was formed via a four-layer self-assembly technique. A chelate of tannic acid and iron ions was encapsulated within the wall material at a molar ratio of 1:3. The resulting pH-responsive microcapsules were homogenized at 50 MPa using a high-pressure homogenizer, yielding a particle size of 250 nm.

[0064] 4. Synthesis of waterborne polyurethane-acrylic hybrid resin: Isophorone diisocyanate and polytetramethylene glycol were mixed at an NCO / OH ratio of 1.95:1, and 0.5% dibutyltin dilaurate catalyst was added at 70°C for 2.5 hours. Subsequently, a dynamic disulfide bond donor and hydroxyethyl acrylate (molar ratio of 1:1.1) were added for cross-linking. Finally, 0.3% aminosilane was added to create a surface amino gradient, resulting in the final waterborne polyurethane-acrylic hybrid resin.

[0065] 5. Ink system construction: The prepared pH-responsive microcapsules were mixed with γ-valerolactone at a weight ratio of 5:10 and treated with ultrasound at a power of 90 W for 15 minutes. After adding the polyglycerol ester surfactant, the microcapsules were treated with ultrasound at a shear rate of 800 s -1 Mix in a high-speed disperser. Then, add nanocellulose crystals, water-based polyurethane-acrylic hybrid resin, and modified plant polyphenol pigment in sequence, adjusting the pH to 7.4. Finally, top up with deionized water and filter through a 180-mesh sieve to obtain the final water-based, environmentally friendly, mutually exclusive ink product.

[0066] Example 3: Component ratio: Waterborne polyurethane-acrylic hybrid resin: 25 parts; nanocellulose crystals: 5 parts; modified plant polyphenol pigment: 22 parts; γ-valerolactone: 15 parts; polyglycerol ester surfactant: 4 parts; pH-responsive microcapsules: 8 parts.

[0067] Preparation steps: 1. Preparation of Nanocellulose Crystals: Bamboo pulp cellulose was mixed with a 65% sulfuric acid solution in a 1:6 mass ratio. The reaction temperature was controlled at 50°C and the hydrolysis treatment was carried out for 2.5 hours. After the reaction, solid-liquid separation was performed using a centrifuge at 9000 rpm and the product was washed with deionized water until the pH was greater than 5.5. Subsequently, an ultrasonic device with a frequency of 45 kHz was used for 35 minutes to obtain nanocellulose crystals with a solid content of 9%.

[0068] 2. Modification of plant polyphenol pigments: Tea polyphenols were dissolved in deionized water to prepare a 35% solution. Ferric chloride hexahydrate was added at a molar ratio of 1:3.2 (iron ion:tea polyphenol). The reaction temperature was controlled at 65°C for 2.2 hours. After the reaction, the solution was converted into a powder in a spray dryer with an inlet air temperature of 200°C to obtain a modified plant polyphenol pigment powder.

[0069] 3. Preparation of pH-responsive microcapsules: Graphene oxide and chitosan were dissolved in deionized water at a mass ratio of 1:2.8, and a five-layer self-assembly technique was used to form the microcapsule wall material. A chelate of tannic acid and iron ions was encapsulated within the wall material at a molar ratio of 1:2.9. The resulting pH-responsive microcapsules were homogenized at 100 MPa using a high-pressure homogenizer, yielding a particle size of 350 nm.

[0070] 4. Synthesis of waterborne polyurethane-acrylic hybrid resin: Isophorone diisocyanate and polytetramethylene glycol were mixed at an NCO / OH ratio of 2.05:1, and 0.6% dibutyltin dilaurate catalyst was added at 80°C for 3.5 hours. Subsequently, a dynamic disulfide bond donor and hydroxyethyl acrylate (molar ratio of 1:1.3) were added for cross-linking. Finally, 0.5% aminosilane was added to create a surface amino gradient, resulting in the final waterborne polyurethane-acrylic hybrid resin.

[0071] 5. Ink system construction: The prepared pH-responsive microcapsules were mixed with γ-valerolactone at a weight ratio of 8:15 and treated with ultrasound at a power of 110 W for 20 minutes. After adding the polyglycerol ester surfactant, the microcapsules were treated with an ultrasound at a shear rate of 1250 s -1 Mix in a high-speed disperser. Then, add nanocellulose crystals, water-based polyurethane-acrylic hybrid resin, and modified plant polyphenol pigment in sequence, and adjust the pH to 8.1. Finally, add deionized water and filter through a 180-mesh sieve to obtain the final water-based, environmentally friendly, mutually exclusive ink product.

[0072] Comparative Example 1: Compared with Example 1, the difference is that no dynamic disulfide bond donor is used for cross-linking in the waterborne polyurethane-acrylic hybrid resin, and the dynamic cross-linking step is removed. The rest are the same.

[0073] Comparative Example 2: Compared with Example 1, the difference is that the chelation reaction between iron ions and tea polyphenols is not carried out in the modified plant polyphenol pigment, but unmodified tea polyphenols are directly used, and the rest are the same.

[0074] Comparative Example 3: Compared with Example 1, the difference is that graphene oxide and chitosan are not used to composite in the pH-responsive microcapsules, but pure chitosan wall material is used instead, and layer-by-layer self-assembly is not performed. The rest are the same.

[0075] Comparative Example 4: Compared with Example 1, the difference is that in the preparation process of nanocellulose crystals, the ultrasonic treatment step is not used, and the solid-liquid separation and water washing steps are directly carried out. The rest are the same.

[0076] Comparative Example 5: Compared with Example 1, the difference is that in the process of constructing the ink system, polyglycerol ester surfactant is not used, and ordinary surfactant is directly used. The rest are the same.

[0077] Comparative Example 6: Compared with Example 1, the difference is that during the synthesis of the waterborne polyurethane-acrylic hybrid resin, aminosilane was not added for surface modification, but polyurethane resin was used directly, and the rest were the same.

[0078] Experiment 1: Purpose of the experiment: By comparing Example 1 with Comparative Examples 1 and 2, the effects of the dynamic crosslinking of the waterborne polyurethane-acrylic hybrid resin and the chelating effect of the modified plant polyphenol pigment on the ink properties were tested, with particular attention paid to the mechanical properties, color stability and coating properties of the ink.

[0079] Experimental groups: Example 1: Ink containing dynamically cross-linked and chelated pigments; Comparative Example 1: Ink without the dynamic cross-linking step; Comparative Example 2: The chelating step was omitted and the ink containing tea polyphenols was used directly.

[0080] Experimental steps: 1. Mechanical properties test: The tensile strength, elongation at break, and hardness of each ink sample were measured using a tensile tester. The tensile strength test used standard tensile test pieces, with at least five specimens tested for each sample, and the maximum tensile strength and elongation at break values ​​recorded.

[0081] 2. Color stability test: The ink was applied to a white plastic substrate and then treated with UV light (UV lamp, 365nm) and room temperature heating (60°C) for 24 hours. After treatment, the color difference (ΔE) value was measured using a spectrophotometer to record the ink's color stability, specifically the color changes after UV light irradiation and heat treatment.

[0082] 3. Coating performance test: The ink was applied to standard paper and plastic substrates and tested for adhesion, fluidity, and gloss. Gloss was measured using a standard glossmeter, adhesion was tested using the tape stripping method, and fluidity was evaluated by analyzing the ink's viscosity using a rotational viscometer (experimental data are shown in Table 1).

[0083] Table 1: Ink performance comparison data table From Table 1, we can get: This experiment, by comparing example 1 and comparative example 1, 2, can clearly observe the significant impact of the dynamic crosslinking of waterborne polyurethane-acrylic acid hybrid resin and the chelating technology of modified plant polyphenol pigment on ink performance. In embodiment 1, the introduction of dynamic crosslinking and chelating pigment helps to improve the tensile strength and elongation at break of ink, especially shows higher numerical value in hardness and adhesion. This effect can be attributed to the dynamic disulfide bond structure in waterborne polyurethane-acrylic acid hybrid resin, and this structure not only improves the bonding properties of resin, but also strengthens the resilience of resin under mechanical load, so that ink has stronger tensile properties and lower elongation at break. By contrast, removing the dynamic crosslinking step (comparative example 1) has caused the decline of ink tensile strength, shows that dynamic crosslinking has played an important role to the overall performance of resin.

[0084] The chelating effect of the modified plant polyphenol pigment also plays a crucial role in the color stability of the ink. The tea polyphenols in Example 1 can significantly improve the color stability of the ink under ultraviolet light irradiation and heat treatment through the chelation reaction with iron ions, while removing the chelation step (Comparative Example 2) leads to an increase in the color difference (ΔE value) of the ink after light and heat treatment. This shows that the chelation reaction between iron ions and tea polyphenols not only enhances the stability of the pigment, but also effectively inhibits the fading phenomenon of the pigment under environmental changes, further demonstrating the importance of pigment modification in water-based inks.

[0085] Furthermore, in coating performance tests, the ink of Example 1 demonstrated superior gloss and adhesion, which is closely related to its higher surface amino concentration and optimized dispersibility. The surface amino gradient control and microcapsule introduction of the waterborne polyurethane-acrylic hybrid resin enhanced the ink's wettability and adhesion to a certain extent, ensuring its stability and uniformity on various substrates. In contrast, the samples of Comparative Examples 1 and 2, which failed to utilize these innovative technologies, exhibited relatively poor coating performance. This result further demonstrates the role of surface modification techniques and innovative dispersion methods in enhancing the performance of water-based inks.

[0086] Experiment 2: Purpose of the experiment: By comparing Example 1 with Comparative Examples 3 and 4, the effects of the structure of pH-responsive microcapsules and the dispersion properties of nanocellulose crystals on ink stability were tested, focusing on the contribution of the pH-responsive characteristics of the microcapsules and the dispersion properties of cellulose to ink stability and function.

[0087] Experimental groups: Example 1: Ink containing pH-responsive microcapsules and ultrasonically treated nanocellulose crystals; Comparative Example 3: ink without pH-responsive microcapsules composited with graphene oxide and chitosan; Comparative Example 4: Ink without using ultrasonic treatment on nanocellulose crystals.

[0088] Experimental steps: 1. pH responsiveness test: Each ink was coated on a transparent plastic sheet and exposed to solutions with different pH values ​​(pH 4, 7, and 10). The color changes of the ink in these environments were observed every 30 minutes, and the ΔE value of the color change was measured using a spectrophotometer. The color development and fading responses of the ink were recorded.

[0089] 2. Nanocellulose dispersion performance test: Scanning electron microscopy (SEM) was used to observe the dispersion of the nanocellulose crystals in the ink, particularly in the ink that had not been ultrasonically treated to detect any agglomeration. The uniformity of the cellulose dispersion in the different ink samples was compared, and the degree of cellulose agglomeration was recorded.

[0090] 3. Ink stability test: To test the long-term storage stability of the ink, place the ink sample at room temperature, take samples regularly, and observe the stratification of the ink. The dispersion stability of the ink is evaluated through viscosity testing and particle distribution testing (dynamic light scattering). The time and frequency of occurrence of stratification and sedimentation are recorded (experimental data are shown in Table 2).

[0091] Table 2: Comparison of ink responsiveness and dispersion performance From Table 2, we can get: In Experiment 2, the effects of pH-responsive microcapsules and ultrasonically treated nanocellulose crystals in ink were verified by comparing Example 1 with Comparative Examples 3 and 4. The microcapsules in Example 1, with graphene oxide and chitosan forming a stable wall material, maintain relatively consistent responsiveness across varying pH values, exhibiting optimal color change at an alkaline pH of 10. In contrast, Comparative Example 3, in which the microcapsule wall material is removed, exhibits larger ΔE values ​​across different pH conditions, demonstrating the instability of its color response and demonstrating the critical role of the graphene oxide and chitosan composite wall material in microcapsule performance.

[0092] At the same time, the dispersion performance of the ultrasonically treated nanocellulose in Example 1 was significantly better than that in Comparative Example 4. SEM image analysis shows that the nanocellulose crystals in Example 1 are more evenly dispersed, with no agglomeration. In Comparative Example 4, due to the lack of ultrasonic treatment, the cellulose crystals exhibited greater agglomeration, affecting the uniformity and stability of the ink. This also explains why Comparative Example 4 experienced rapid stratification and sedimentation during long-term storage, indicating that ultrasonic treatment of the nanocellulose crystals plays a crucial role in the dispersibility and stability of the ink.

[0093] Finally, ink stability testing further demonstrated the superiority of Example 1. At room temperature, the ink of Example 1 exhibited no delamination, while Comparative Examples 3 and 4 exhibited varying degrees of delamination and sedimentation during storage. Comparative Example 4 exhibited the worst stability, experiencing delamination for only one day. This demonstrates the contribution of the excellent dispersion of microcapsules and cellulose to the long-term stability of the ink, further supporting the importance of the microcapsule structure and ultrasonic treatment technology employed in this invention.

[0094] Experiment 3: Purpose of the experiment: By comparing Example 1 with Comparative Examples 5 and 6, the effects of surfactants and surface amino group adjustment on the surface properties, dispersibility and final effect of the ink were tested, focusing on the role of surfactants in wettability and dispersibility, and the contribution of aminosilane surface modification to adhesion and coating performance.

[0095] Experimental groups: Example 1: ink comprising a polyglycerol ester surfactant and an aminosilane surface-modified resin; Comparative Example 5: ink without using polyglycerol ester surfactant; Comparative Example 6: ink without surface modification using aminosilane.

[0096] Experimental steps: 1. Surface tension test: Ink samples were coated onto standard glass substrates. The surface tension of each ink sample on the substrate was measured using a surface tensiometer. The wettability of different samples was tested at different time intervals, and the changes in surface tension of the ink were recorded.

[0097] 2. Adhesion test: Adhesion testing was performed using a tensile tester. Each ink was applied to standard paper and plastic substrates and the adhesive tape peeling method was used to test the ink adhesion. The adhesion strength of each sample was recorded in kgf.

[0098] 3. Particle size distribution and dispersion stability: A laser particle size analyzer was used to measure the particle size distribution of each component in the ink samples, specifically the distribution of microcapsules and nanocellulose crystals. The effects of surfactants and aminosilane on dispersibility were also analyzed. The particle size and dispersion stability of the different ink samples were recorded (experimental data are shown in Table 3).

[0099] Table 3: Comparative data of ink surface properties and dispersion From Table 3 we can get: Experiment 3, comparing Example 1 with Comparative Examples 5 and 6, clearly demonstrates the crucial role of surfactants and surface amino group modification in ink surface properties and stability. In Example 1, the use of a polyglycerol ester surfactant and an aminosilane surface-modified resin resulted in a lower surface tension on the substrate, exhibiting better wettability and leveling. This reduced surface tension allows for more even distribution of the ink during coating, avoiding uneven coating and enhancing ink adhesion.

[0100] Compared to Comparative Examples 5 and 6, Example 1 exhibits significantly lower surface tension, which is closely related to the addition of the polyglycerol ester surfactant. As a nonionic surfactant, polyglycerol ester reduces the ink's surface tension, improving its wettability and making it easier to form a uniform coating on the substrate surface. In contrast, in Comparative Example 5, the absence of a polyglycerol ester surfactant resulted in poor wettability of the ink on the substrate surface, resulting in poor coating quality and high surface tension, which affected the ink's leveling and adhesion.

[0101] In terms of adhesion, the ink of Example 1 exhibited stronger adhesion, primarily due to the surface modification effect of aminosilane. Aminosilane forms an amino gradient structure on the resin surface, enhancing the ink's affinity and adhesion to the substrate surface, thereby improving adhesion. The ink of Comparative Example 6, which lacked aminosilane surface modification, exhibited significantly lower adhesion and poor coating performance, particularly on plastic substrates.

[0102] Finally, the dispersion stability test results further demonstrate the impact of surfactants and surface amino group modification on ink stability. The ink in Example 1 exhibited good dispersion stability, with components in the ink maintaining a stable distribution and no stratification. In contrast, in Comparative Examples 5 and 6, due to the lack of surfactants and surface modification, the ink particles showed significant agglomeration, resulting in poor dispersion stability and more frequent stratification and sedimentation. The combination of surfactants and aminosilanes provided the ink with improved dispersibility and long-term stability, ensuring consistency and stability during storage.

[0103] The examples of this specific embodiment are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, any equivalent changes made based on the structure, shape, and principle of this application should be included in the scope of protection of this application.

Claims

1. A water-based environmentally friendly mutually exclusive ink, characterized in that: The composition comprises the following components in parts by weight: Waterborne polyurethane-acrylic acid hybrid resin: 18-25 parts; Nanocellulose crystals: 3-5 parts; Modified plant polyphenol pigment: 15-22 parts; γ-valerolactone: 10-15 parts; Polyglycerol ester surfactant: 2-4 parts; pH-responsive microcapsules: 5-8 parts.

2. The water-based environmentally friendly mutually exclusive ink according to claim 1, characterized in that: The waterborne polyurethane-acrylic acid hybrid resin comprises: A prepolymer formed by the reaction of isophorone diisocyanate and hydroxyethyl acrylate; The content of dynamic disulfide bonds in the prepolymer accounts for 0.5-1.5% of the total mass of the waterborne polyurethane-acrylic hybrid resin; The surface amino concentration of the waterborne polyurethane-acrylic acid hybrid resin is 2.0-2.2 mmol / m 2 , the internal amino concentration is 0.7-0.9mmol / m 2 .

3. The water-based environmentally friendly mutually exclusive ink according to claim 1, characterized in that: The modified plant polyphenol pigment comprises: A complex is formed by a chelation reaction between tea polyphenols and iron ions, wherein the molar ratio of iron ions to polyphenols is 1:2.8-3.

2.

4. The water-based environmentally friendly mutually exclusive ink according to claim 1, characterized in that: The pH-responsive microcapsules include: A wall material formed by compounding graphene oxide and chitosan in a mass ratio of 1:2.8-3.2; The tannic acid and iron ion chelate is encapsulated in the wall material, wherein the molar ratio of the tannic acid to the iron ion is 1:2.9-3.

1.

5. A method for preparing the water-based environmentally friendly mutually exclusive ink according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1, preparation of nanocellulose crystals; S2, plant polyphenol pigment modification; S3, preparation of pH-responsive microcapsules; S4, synthesis of waterborne polyurethane-acrylic hybrid resin; S5. Ink system construction.

6. The method for preparing a water-based environmentally friendly mutually exclusive ink according to claim 5, characterized in that: The nanocellulose crystal preparation comprises: Mix bamboo pulp cellulose with a sulfuric acid solution having a mass concentration of 60-65% in a mass ratio of 1:4-6; Hydrolysis treatment was performed at 40-50°C for 1.5-2.5 hours; Use a centrifuge with a speed of 7000-9000 rpm for solid-liquid separation and wash with deionized water until the pH is greater than 5.5; The nanocellulose crystals with a solid content of 7-9% were obtained by treating with an ultrasonic device at a frequency of 35-45 kHz for 25-35 minutes.

7. The method for preparing a water-based environmentally friendly mutually exclusive ink according to claim 5, characterized in that: The plant polyphenol pigment modification comprises: Dissolve tea polyphenols in deionized water to prepare a solution with a mass concentration of 25-35%; Add ferric chloride hexahydrate at a molar ratio of iron ion to polyphenols of 1:2.8-3.2; Stir the reaction at 55-65°C for 1.8-2.2 hours; The modified pigment powder is prepared by a spray drying tower with an inlet air temperature of 180-200°C.

8. The method for preparing a water-based environmentally friendly mutually exclusive ink according to claim 5, characterized in that: The preparation of the pH-responsive microcapsules comprises: Graphene oxide and chitosan are self-assembled layer by layer in a mass ratio of 1:2.8-3.2 for 4-6 layers; Encapsulating a chelate prepared by mixing tannic acid and iron ions in a molar ratio of 1:2.9-3.1 in the wall material; A high-pressure homogenizer is used to control the particle size of the pH-responsive microcapsules to be 250-350 nm at a pressure of 50-100 MPa.

9. The method for preparing a water-based environmentally friendly mutually exclusive ink according to claim 5, characterized in that: The synthesis of the waterborne polyurethane-acrylic acid hybrid resin comprises: Isophorone diisocyanate and polytetramethylene glycol are mixed at NCO / OH=1.95-2.05:1; Add 0.4-0.6% of dibutyltin dilaurate catalyst to the total mass of the system and react at 70-80°C for 2.5-3.5 hours; A dynamic disulfide bond donor was introduced and cross-linked with hydroxyethyl acrylate at a molar ratio of 1:1.1-1.3; The surface amino gradient was constructed by adding 0.3-0.5% of aminosilane to the waterborne polyurethane-acrylic hybrid resin.

10. The method for preparing a water-based environmentally friendly mutually exclusive ink according to claim 5, characterized in that: The ink system construction includes: The pH-responsive microcapsules and γ-valerolactone were mixed in a weight ratio of 5-8:10-15, and ultrasonic treatment was performed with a power of 90-110 W for 10-20 minutes; After adding polyglycerol ester surfactant, use shear rate 750-1250s -1 High-speed disperser mixing; Nanocellulose crystals, waterborne polyurethane-acrylic hybrid resin, and modified plant polyphenol pigment were sequentially added, and the pH was adjusted to 7.4-8.1; After adding deionized water, filter through a 180-220 mesh sieve to obtain the final ink product.

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