Self-cleaning ink and preparation method thereof

Abstract

This invention, in the field of ink technology, specifically proposes a self-cleaning ink and its preparation method. Using atomic layer deposition, a double-shell structure is constructed on the surface of anatase TiO2. The inner layer is a dense 2-5nm SiO2 isolation layer, and the outer layer is a photoresponsive polyurethane. Dynamic coating is formed by 365nm UV curing. The ink formulation includes polyurethane acrylate, a diluent, a photoinitiator, a double-shell TiO2 layer, and an additive. Through the synergistic effects of energy band modulation, dynamic coating, and free radical capture, the present invention combines efficient self-cleaning, long-lasting weathering resistance, and environmental protection.

Description

Technical Field

[0001] The present invention relates to the technical field of ink, in particular to a self-cleaning ink and a preparation method thereof. Background Art

[0002] UV-curable inks are currently widely used in the printing industry. UV inks cure in seconds through ultraviolet light, eliminating the oxidation and drying process required by traditional inks. This improves printing efficiency and makes them particularly suitable for high-speed automated production lines. UV inks also contain no volatile organic compounds, aligning with the trend toward green industrial development. Furthermore, the cured ink film is abrasion-resistant, water-resistant, and solvent-resistant, resulting in a more saturated appearance.

[0003] However, while traditional UV inks claim to be solvent-free, they still contain some volatile components. By adding catalysts for self-cleaning, residual solvents can be further reduced or eliminated, improving safety. While the anatase titanium dioxide used in existing UV inks possesses photocatalytic self-cleaning properties, the free radicals it produces can oxidatively decompose the printed layer, causing discoloration and aging. Current technology primarily uses a single-layer coating to inhibit free radical leakage, but this presents the following issues: 1. Conventional static protection employs a single-layer coating structure, which can completely shield the photocatalytic activity, rendering the self-cleaning function ineffective. 2. Due to the single nature of the coating structure, when anatase titanium dioxide generates free radicals, the diffusion process is relatively random, easily damaging the interior of the printed layer.

[0004] In view of this, how to reduce the destructive effect of titanium dioxide on the printed layer while maintaining good decontamination and self-cleaning capabilities has become one of the technical problems that need to be solved urgently. Summary of the Invention

[0005] In view of this, in order to address the above-mentioned deficiencies in the prior art, the present invention provides a self-cleaning ink and a preparation method thereof that can reduce damage to the printing layer.

[0006] The technical solution of the present invention is achieved as follows: The present invention provides a self-cleaning ink, the raw materials of which are calculated by weight and include: 40-50 parts of prepolymer, 20-30 parts of diluent, 5-8 parts of photoinitiator, 8-12 parts of double-shell anatase TiO2, 3-5 parts of dispersant, and 2-4 parts of additives. The double-shell anatase TiO2 includes an inner shell layer and an outer shell layer, the inner shell layer is SiO2, and the outer shell layer is photoresponsive polyurethane.

[0007] In some embodiments, the method for preparing double-shell anatase TiO2 comprises the following steps:

[0008] S1. Dissolve tetrabutyl titanate in an ethanol-water solution (ethanol:water=1:3 (v:v)), adjust the pH to 3, heat to 80°C, and keep the reaction for 12 hours. Centrifuge, wash, and dry at 60°C for 12 hours to obtain anatase TiO2 nanoparticles.

[0009] S2. The TiO2 nanoparticles prepared in step 1 are placed in a reaction chamber of an atomic deposition apparatus, SiCl4 is used as a silicon source, and water is used as an oxidant. The deposition temperature is 200°C, and 50 cycles are performed. SiCl4 and water are introduced into the reaction chamber for 0.5s and 1s respectively in each cycle to prepare TiO2 nanoparticles with SiO2 deposited on the surface.

[0010] S3, the SiO2@TiO2 prepared in step 2 was dispersed in the ethyl acetate solution of polyurethane prepolymer containing azobenzene groups, 365nm, 10mW / cm 2 UV curing is performed for 10-60 seconds to form a cross-linked outer shell layer, and double-shell anatase TiO2 is obtained after filtration and washing.

[0011] In the above scheme, a double-shelled anatase TiO2 is used to achieve dynamic protection through the synergistic effect of the inner SiO2 layer and the outer photoresponsive polyurethane layer. The inner SiO2 shell is formed into a dense inorganic layer using atomic layer deposition technology. Through physical isolation, it blocks the migration of photogenerated holes into the interior of the ink, reducing the oxidative damage of free radicals to the organic matrix. The polyurethane containing azobenzene groups is stable after UV curing, but it degrades under a specific wavelength of visible light (450-550nm), exposing the inner shell and activating the TiO2 photocatalytic activity, achieving on-demand self-cleaning. When not activated, the outer shell shields ultraviolet rays and inhibits the photocatalytic reaction. When activated, the outer shell degrades, releasing the TiO2 activity, balancing the self-cleaning needs with substrate protection.

[0012] In some embodiments, in S1, before the heating and insulation reaction, it also includes: adding Fe(NO3)3 and NH4F to the ethanol aqueous solution, the amount of Fe(NO3)3 is 1-3% of the molar amount of TiO2, and the amount of NH4F is 5-8% of the molar amount of TiO2.

[0013] In the above embodiment, Fe 3+ and F - Co-doping optimizes the radical migration direction through the following mechanisms: Fe 3+ Replace Ti 4 + Introducing an intermediate energy level, reducing the band gap to 2.8eV, and enhancing the visible light response; F -Adsorbing surface hydroxyl groups optimizes the conduction band to -0.6eV, driving holes to migrate preferentially to the surface. This shortens the hole migration path, reduces penetration into the ink, improves self-cleaning efficiency, forms a carrier "highway," suppresses the electron-hole recombination rate, and reduces the risk of internal damage.

[0014] In some embodiments, in S3, the mass ratio of SiO2@TiO2 to the polyurethane prepolymer containing azobenzene groups is 1:(1-1.5).

[0015] The polyurethane prepolymer containing azobenzene groups can be directly purchased or prepared. The preparation method includes:

[0016] a) reacting polytetrahydrofuran (Mn=2,000) with isophorone diisocyanate at 70° C. for 4 hours to obtain a prepolymer having an NCO content of 6-8%;

[0017] b) adding 4,4'-dihydroxyazobenzene (10 mol%) and continuing the reaction for 2 h;

[0018] c) removing unreacted monomers by distillation under reduced pressure to obtain a prepolymer having a molecular weight of 12,000±500 g / mol and an azobenzene content of 10 mol%.

[0019] In some embodiments, the photoinitiator includes a thiol, and the thiol includes at least one of 1-decanethiol and 1-nonanethiol.

[0020] In some embodiments, the photoinitiator further comprises camphorquinone, and the mass ratio of thiol to camphorquinone is 3:2.

[0021] In the above embodiment, the prepolymer is quickly cross-linked by sulfhydryl radicals, shortening the curing time to 0.5s, reducing the possibility of oxidation of uncured residues, and camphorquinone extends the absorption wavelength to 450nm, matching the visible light response of Fe / F-TiO2, synergistically improving the curing efficiency; after curing, a dense cross-linked network is formed, reducing the porosity of the ink, and blocking free radicals from penetrating into the printed layer.

[0022] In some embodiments, the auxiliary agent includes a leveling agent, and the leveling agent is a polysiloxane leveling agent BYK-307.

[0023] In some embodiments, the auxiliary agent further comprises carboxylated carbon quantum dots with a particle size of 2-5 nm, and the mass ratio of the quantum dots to the leveling agent is 1:2.

[0024] In the above embodiment, the polysiloxane structure reduces the surface tension of the ink, ensures the uniformity of the coating, and avoids damage caused by excessive local TiO2 concentration. The carboxylated carbon quantum dots adsorb escaping free radicals through π-π interaction and catalyze their conversion into CO2 / H2O. The mass ratio of the dots to the leveling agent is 1:2, which balances the free radical capture and the ink leveling performance and reduces the cumulative damage to the substrate.

[0025] In some embodiments, the prepolymer includes at least one of polyurethane acrylate and epoxy acrylate, the diluent includes at least one of DCPD and HDDA, and the dispersant includes at least one of hyperbranched acrylate oligomer and polyether-modified polysiloxane.

[0026] In a second aspect, the present invention further provides a method for preparing the above-mentioned ink, comprising the following steps:

[0027] Step 1: Stir the prepolymer, diluent and photoinitiator at 45-55°C for 30-60 minutes until homogeneous;

[0028] Step 2: Add double-shell TiO2 and dispersant, and ball mill at 200-400 rpm for 20-40 minutes

[0029] Step 3: After vacuum degassing at -0.1 MPa for 30 minutes, add the additive and mix evenly to obtain a self-cleaning ink.

[0030] In some embodiments, in step 2, the ball milling temperature is 25-30° C., and the ball milling uses zirconia beads with a diameter of 0.3 mm.

[0031] The present invention has the following beneficial effects compared to the prior art:

[0032] Compared with the traditional TiO2 self-cleaning solution, this application adopts double-shell titanium dioxide, which solves the contradiction between photocatalytic activity and collective protection through the synergistic solution of dynamic coating, energy band regulation and free radical capture. While maintaining good self-cleaning ability, it also maintains the life of the coating and has good application prospects. DETAILED DESCRIPTION

[0033] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described 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.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which embodiments of the present invention belong. If the definitions set forth in this section are contrary to or otherwise inconsistent with definitions set forth in the patents, patent applications, published patent applications, and other publications incorporated herein by reference, the definitions listed in this section take precedence over the definitions incorporated herein by reference.

[0035] Unless otherwise specified, the methods used in the following examples are conventional methods. The materials, reagents, and instruments used are conventional materials, reagents, and instruments in the art, unless otherwise specified, and can be obtained commercially by those skilled in the art.

[0036] When an amount, concentration or other value or parameter is expressed as a range, a preferred range or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any upper range limit or preferred value with any lower range limit or preferred value, regardless of whether the range is disclosed alone. For example, when a range "1 to 5" is disclosed, the described range should be interpreted as including the ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within the range. In the present specification and claims, range definitions may be combined and / or interchanged, and if not otherwise stated, such ranges include all subranges contained therein.

[0037] Example 1

[0038] This embodiment provides a technical solution of combining double-shell TiO2 with a conventional photoinitiator.

[0039] The ingredients are as follows:

[0040] 45 parts of prepolymer polyurethane acrylate, 25 parts of diluent HDDA, 6 parts of photoinitiator TPO, 10 parts of double-shell TiO2, 4 parts of dispersant hyperbranched acrylate, and 3 parts of leveling agent BYK-307.

[0041] The preparation method of double-shell TiO2 is as follows:

[0042] 0.2 mol of tetrabutyl titanate was dissolved in 1 L of ethanol-water solution (ethanol:water=1:3 (v:v)), the pH value was adjusted to 3, and the mixture was heated to 80°C for 12 h. After centrifugation and washing, the mixture was dried at 60°C for 12 h to obtain anatase TiO2 nanoparticles.

[0043] The prepared TiO2 nanoparticles were placed in the reaction chamber of an atomic deposition apparatus, with SiCl4 as the silicon source and water as the oxidant. The deposition temperature was 200°C, and 50 cycles were performed. SiCl4 was introduced for 0.5 seconds and water for 1 second in each cycle to prepare TiO2 nanoparticles with SiO2 deposited on the surface.

[0044] The prepared SiO2@TiO2 was dispersed in an ethyl acetate solution of a polyurethane prepolymer containing azobenzene groups, where the mass ratio of SiO2@TiO2 to the polyurethane prepolymer containing azobenzene groups was 1:1. UV curing was performed at 365nm, 10mW / cm2 ultraviolet light for 30s to form a cross-linked shell layer. After filtration and washing, double-shell anatase TiO2 was obtained.

[0045] The preparation method of the above-mentioned polyurethane prepolymer containing azobenzene group is as follows:

[0046] a) reacting polytetrahydrofuran (Mn=2,000) with isophorone diisocyanate at 70° C. for 4 hours to obtain a prepolymer having an NCO content of 6-8%;

[0047] b) adding 4,4'-dihydroxyazobenzene (10 mol%) and continuing the reaction for 2 h;

[0048] c) removing unreacted monomers by distillation under reduced pressure to obtain a prepolymer having a molecular weight of 12,000±500 g / mol and an azobenzene content of 10 mol%.

[0049] Preparation method of self-cleaning ink:

[0050] Step 1: Stir the prepolymer, diluent and photoinitiator at 50°C for 30 minutes until homogeneous;

[0051] Step 2: Add double-shell TiO2 and dispersant, and ball mill at 300 rpm for 30 minutes

[0052] Step 3: After vacuum degassing at -0.1 MPa for 30 minutes, add the additive and mix evenly to obtain a self-cleaning ink.

[0053] Example 2

[0054] This embodiment uses Fe / F doped double-shell TiO2 on the basis of embodiment 1, and uses a thiol-camphorquinone composite photoinitiator. Other conditions remain unchanged. Specifically:

[0055] The ingredients are as follows:

[0056] 45 parts of prepolymer polyurethane acrylate, 25 parts of diluent HDDA, 6 parts of photoinitiator (composed of 1-decanethiol:camphorquinone mass ratio = 3:2), 10 parts of Fe / F-doped double-shell TiO2, 4 parts of dispersant hyperbranched acrylate, and 3 parts of leveling agent BYK-307.

[0057] The preparation method of Fe / F-doped double-shell TiO2 is as follows:

[0058] 0.2 mol of tetrabutyl titanate was dissolved in 1 L of ethanol-water solution (ethanol:water=1:3 (v:v)), and the pH value was adjusted to 3. 0.002 mol of Fe(NO3)3 and 0.01 mol of NH4F were added, and the mixture was heated to 80°C and kept for 12 h. After centrifugation and washing, the mixture was dried at 60°C for 12 h to obtain anatase TiO2 nanoparticles.

[0059] The prepared TiO2 nanoparticles were placed in the reaction chamber of an atomic deposition apparatus, with SiCl4 as the silicon source and water as the oxidant. The deposition temperature was 200°C, and 50 cycles were performed. SiCl4 was introduced for 0.5 seconds and water for 1 second in each cycle to prepare TiO2 nanoparticles with SiO2 deposited on the surface.

[0060] The prepared SiO2@TiO2 was dispersed in an ethyl acetate solution of a polyurethane prepolymer containing azobenzene groups, where the mass ratio of SiO2@TiO2 to the polyurethane prepolymer containing azobenzene groups was 1:1. UV curing was performed at 365nm, 10mW / cm2 ultraviolet light for 30s to form a cross-linked shell layer. After filtration and washing, double-shell anatase TiO2 was obtained.

[0061] Example 3

[0062] This embodiment, based on Example 2, uses a higher ratio of Fe / F doped double-shell TiO2 and a thiol-camphorquinone composite photoinitiator. Other conditions remain unchanged. Specifically:

[0063] In the preparation method of Fe / F-doped double-shell TiO2:

[0064] 0.2 mol of tetrabutyl titanate was dissolved in 1 L of ethanol aqueous solution, ethanol: water = 1:3 (v:v), and the pH value was adjusted to 3. Then 0.006 mol of Fe(NO3)3 and 0.016 mol of NH4F were added, heated to 80°C and kept for reaction for 12 hours. After centrifugation and washing, it was dried at 60°C for 12 hours to obtain anatase TiO2 nanoparticles; the subsequent steps were the same as in Example 2.

[0065] Example 4

[0066] On the basis of Example 2, this example further introduces carboxylated carbon quantum dots, whose particle size is 2-5 nm and whose mass ratio to the leveling agent BYK-307 is 1:2.

[0067] Comparative Example 1

[0068] This comparative example is based on Example 1, using a polyurethane shell without light response, and other conditions remain unchanged, with the following differences:

[0069] The prepared SiO2@TiO2 was dispersed in an ethyl acetate solution of polyurethane prepolymer, where the mass ratio of SiO2@TiO2 to polyurethane prepolymer was 1:1. UV curing was performed at 365nm, 10mW / cm2 ultraviolet light for 30s to form a cross-linked shell layer. After filtration and washing, double-shell anatase TiO2 was obtained.

[0070] The preparation method of the polyurethane prepolymer is as follows:

[0071] a) reacting polytetrahydrofuran (Mn=2,000) with isophorone diisocyanate at 70° C. for 4 hours to obtain a prepolymer having an NCO content of 6-8%;

[0072] b) removing unreacted monomers by distillation under reduced pressure to obtain a polyurethane prepolymer.

[0073] Comparative Example 2

[0074] This comparative example is based on Example 2, in which the double-shell TiO2 is not doped with Fe / F, and the other steps are the same, with the following specific differences:

[0075] 0.2 mol of tetrabutyl titanate was dissolved in 1 L of ethanol aqueous solution, ethanol: water = 1:3 (v:v), the pH value was adjusted to 3, heated to 80°C and kept for reaction for 12 hours, centrifuged, washed, and dried at 60°C for 12 hours to obtain anatase TiO2 nanoparticles; other parameters and steps were the same as in Example 2.

[0076] Comparative Example 3

[0077] This comparative example is based on Example 2, but uses TPO photoinitiator to replace the thiol-camphorquinone composite system.

[0078] The performance of the inks prepared in the above different embodiments and comparative examples was verified.

[0079] The ink was applied to the glass surface and then UV cured, and then the above tests were performed.

[0080] Self-cleaning efficiency

[0081] According to ISO 10678:2010 (Degradation performance of organic matter in aqueous solution of photocatalytic materials), a methylene blue solution (0.1 g / L) was sprayed to form a pollution layer, and then placed under a 450 nm LED light source (light intensity 50 mW / cm 2 ) for 24 h, and the absorbance change of methylene blue at 664 nm was measured using a UV-visible spectrophotometer to calculate the degradation rate.

[0082] The self-cleaning efficiency comparison is as follows:

[0083] Grouping Methylene blue degradation rate Example 1 85％ Example 2 95％ Example 3 98％ Example 4 96％ Comparative Example 1 45％ Comparative Example 2 60％ Comparative Example 3 75％

[0084] Ink durability test

[0085] Use QUV accelerated aging test chamber (UVA-340 lamp, irradiation intensity 0.76W / m 2 , 60℃ light / 50℃ condensation cycle), after 1000 hours of testing:

[0086] Color difference (ΔE): Use a colorimeter (such as X-Rite Ci64) to measure the Lab* values ​​before and after aging and calculate ΔE (ΔE < 2 is excellent, ΔE > 5 is significantly deteriorated).

[0087] Free radical penetration depth and residual amount

[0088] ESR test:

[0089] The concentration of OH radicals in the ink (unit: μmol / g) was measured using an electron paramagnetic resonance spectrometer (ESR), and the penetration depths of different embodiments / comparative examples were compared.

[0090] Fluorescent probe method:

[0091] Terephthalic acid (TA) was used as a fluorescent probe to react with ·OH to generate 2-hydroxyterephthalic acid (the fluorescence intensity was positively correlated with the ·OH concentration). The residual free radical amount was quantitatively determined by a fluorescence spectrophotometer (excitation wavelength 315 nm, emission wavelength 425 nm).

[0092] Band structure and photoresponse characteristics

[0093] UV-Vis DRS test:

[0094] The band gap value (Eg) of TiO2 was determined using UV-visible diffuse reflectance spectroscopy (DRS), and the data was converted using the Kubelka-Munk equation to verify the regulating effect of Fe / F doping on the energy band.

[0095] Photoresponse degradation threshold:

[0096] The coating was irradiated with light sources of different wavelengths (365 nm, 450 nm, and 550 nm), and the degradation time (seconds) of the outer shell layer and the triggering threshold of the photocatalytic activity were measured.

[0097] Curing time and mechanical properties

[0098] Determination of curing time:

[0099] Use UV curing machine (365nm, 10mW / cm 2 ) irradiate the ink coating, monitor the double bond conversion rate in real time by FTIR (>95% is complete curing), and record the required time.

[0100] Mechanical properties test:

[0101] Hardness: Tested according to ASTM D3363 pencil hardness method (H-9H).

[0102] Abrasion resistance: tested according to ASTM D4060 Taber abrasion tester (500 g load, mass loss in mg after 1000 cycles).

[0103] The test results of substrate protection effect are as follows:

[0104]

[0105] Band structure and photoresponse threshold

[0106] Grouping Band gap (eV) Photoresponse threshold (nm) Example 2 2.8 450 Example 3 2.5 550 Comparative Example 2 3.2 388

[0107] Comparison of the data in Example 1 with Comparative Example 1 shows that the dynamic light-responsive shell increases the self-cleaning efficiency from 45% to 85% and reduces ΔE from 5.8 to 2.5. Comparison of the data in Example 2 with Comparative Example 2 shows that Fe / F doping reduces the band gap from 3.2 eV to 2.8 eV and increases the self-cleaning efficiency from 60% to 95%. Comparison of the data in Example 2 with Comparative Example 3 shows that the thiol-camphorquinone system shortens the curing time from 2 seconds to 0.5 seconds and reduces the residual free radicals by 67%.

[0108] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A self-cleaning ink, characterized in that: The invention comprises, by weight, 40-50 parts of a prepolymer, 20-30 parts of a diluent, 5-8 parts of a photoinitiator, 8-12 parts of a double-shell anatase TiO2, 3-5 parts of a dispersant, and 2-4 parts of an auxiliary agent. The photoinitiator comprises thiol and camphorquinone, and the mass ratio of thiol to camphorquinone is 3:

2. The double-shell anatase TiO2 comprises an inner shell layer and an outer shell layer, the inner shell layer is SiO2, and the outer shell layer is a photoresponsive polyurethane. The preparation method of the double-shell anatase TiO2 comprises the following steps: S1. Tetrabutyl titanate was dissolved in an ethanol aqueous solution with an ethanol:water ratio of 1:3 (v:v). The pH value was adjusted to 3. Fe(NO3)3 and NH4F were added to the ethanol aqueous solution. The amount of Fe(NO3)3 was 1-3% of the molar amount of TiO2, and the amount of NH4F was 5-8% of the molar amount of TiO2. The mixture was heated to 80°C and kept for 12 hours. The mixture was centrifuged, washed, and dried at 60°C for 12 hours to obtain anatase TiO2 nanoparticles. S2. Placing the prepared TiO2 nanoparticles in a reaction chamber of an atomic deposition apparatus, using SiCl4 as a silicon source and water as an oxidant, at a deposition temperature of 200°C, performing 50 cycles, with SiCl4 and water being introduced sequentially for 0.5s and 1s in each cycle, to prepare TiO2 nanoparticles with SiO2 deposited on the surface; S3, the prepared SiO2@TiO2 was dispersed in the ethyl acetate solution of polyurethane prepolymer containing azobenzene groups, 365nm, 10mW / cm 2 UV curing is performed for 10-60 seconds to form a cross-linked outer shell layer, and double-shell anatase TiO2 is obtained after filtration and washing.

2. The self-cleaning ink according to claim 1, wherein The thiol includes at least one of 1-decyl mercaptan and 1-nonyl mercaptan.

3. The self-cleaning ink according to claim 1, wherein The auxiliary agent includes a leveling agent, and the leveling agent is a polysiloxane leveling agent BYK-307.

4. The self-cleaning ink according to claim 3, wherein The auxiliary agent also includes carboxylated carbon quantum dots with a particle size of 2-5 nm, and the mass ratio of the quantum dots to the leveling agent is 1:

2.

5. The self-cleaning ink according to claim 1, wherein The prepolymer includes at least one of polyurethane acrylate and epoxy acrylate, the diluent includes at least one of DCPD and HDDA, and the dispersant includes at least one of hyperbranched acrylate oligomer and polyether-modified polysiloxane.

6. The method for preparing the self-cleaning ink according to any one of claims 1 to 5, characterized in that: The steps include: Step 1: Stir the prepolymer, diluent and photoinitiator at 45-55°C for 30-60 minutes until homogeneous; Step 2: Add double-shell TiO2 and dispersant, and ball mill at 200-400 rpm for 20-40 minutes; Step 3: After vacuum degassing at -0.1 MPa for 30 minutes, add the additive and mix evenly to obtain a self-cleaning ink.

7. The method for preparing the self-cleaning ink according to claim 6, wherein: In step 2, the ball milling temperature is 25-30°C.

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