A strippable UV ink and a method of making the same

Abstract

The application discloses a peelable UV ink and a preparation method thereof, and relates to the technical field of UV ink, which comprises the following steps: stirring and premixing a light control de-crosslinking flexible oligomer, a photosensitive silicone acrylate interface agent, a multifunctional acrylate, an active diluent, a pigment, a photoinitiator and an additive in a stirring tank at room temperature to obtain a uniform mixed slurry; grinding and dispersing the mixed slurry to a predetermined fineness to obtain an ink base; and adjusting the viscosity of the ink base, and then performing vacuum degassing treatment to eliminate air bubbles, so as to obtain the peelable UV ink. The UV ink in the application can form a firm and durable protective film after curing, and can be converted into a flexible film after being irradiated by specific light, so that complete and clean peeling can be realized, and the contradiction between the protection performance and the easy peeling property is solved.

Description

Technical Field

[0001] This invention relates to the field of UV ink technology, and more specifically to a peelable UV ink and its preparation method. Background Technology

[0002] In modern precision manufacturing, UV-curable inks are widely used as temporary protective coatings or process masks due to their advantages such as rapid curing, high efficiency and energy saving, and environmental friendliness. For example, in processes such as optical lens grinding, precision metal component machining, automotive parts painting, or integrated circuit board etching, a protective film needs to be coated on the substrate surface to resist harsh environments such as physical wear, chemical corrosion, or high-temperature baking that may be encountered in subsequent processes. To achieve effective protection, this cured ink film must have sufficiently high surface hardness, excellent abrasion resistance, and strong resistance to various chemical solvents. Typically, to achieve these performance requirements, the ink formulation uses a highly cross-linked acrylate resin system, which forms a dense and stable three-dimensional network structure through photo-initiated polymerization, thereby providing solid protection for the substrate.

[0003] However, existing technologies contain an inherent and irreconcilable contradiction. The highly cross-linked network structure built to achieve high protection results in a hard and extremely brittle cured ink film. When it needs to be peeled off after fulfilling its protective function, this highly brittle ink film cannot maintain its integrity and is prone to shattering under external force, forming a large number of tiny fragments. These fragments stubbornly remain on the substrate surface, especially on high-value optical components or complex precision devices. Subsequent cleaning processes become extremely difficult and time-consuming, and may even cause secondary damage to the substrate, seriously affecting product yield and production efficiency. To address this issue, traditional methods primarily involve physically adding plasticizers or introducing flexible resins into the formulation. However, this introduces new technical drawbacks: the addition of plasticizers comes at the cost of sacrificing crosslinking density, significantly reducing the necessary hardness and chemical resistance of the ink film, thus greatly diminishing its protective function; simultaneously, small-molecule plasticizers pose a migration risk, potentially leaching out during use or heating, causing secondary contamination to the protected substrate surface; and physically blended flexible resins often have poor compatibility with the main resin, affecting the ink's storage stability and the uniformity of the cured ink film's performance. Summary of the Invention

[0004] The purpose of this invention is to provide a peelable UV ink and its preparation method, thereby solving the problems existing in the prior art.

[0005] To solve the above-mentioned technical problems, the present invention provides a method for preparing a peelable UV ink, comprising the following steps:

[0006] The photo-controlled decrosslinking flexible oligomer, photosensitive organosilicon acrylate interface agent, multifunctional acrylate, reactive diluent, pigment, photoinitiator and additives are stirred and premixed in a mixing tank at room temperature to obtain a uniform slurry.

[0007] The mixed slurry is ground and dispersed to a predetermined fineness to obtain the ink base material;

[0008] The viscosity of the ink base is adjusted, followed by vacuum degassing to eliminate air bubbles, resulting in a peelable UV ink.

[0009] Preferably, the multifunctional acrylate is a hexafunctional aliphatic polyurethane acrylate; the reactive diluent is trimethylolpropane triacrylate; and the additives include leveling agents and defoamers.

[0010] Preferably, by weight, the composition comprises 30-40 parts of photocontrolled decrosslinking flexible oligomer, 15-25 parts of hexafunctional aliphatic polyurethane acrylate, 10-20 parts of trimethylolpropane triacrylate, 3-7 parts of photosensitive organosilicon acrylate interface agent, 10-20 parts of pigment, 6-10 parts of photoinitiator, and 1-3 parts of additives.

[0011] Preferably, the preparation method of the photocontrolled decrosslinking flexible oligomer includes:

[0012] Step A) 1,3-bis(2-hydroxyethoxy)-2-nitrobenzene, ε-caprolactone monomer, and catalyst (e.g., organotin catalysts such as stannous octoate and dibutyltin dilaurate) are added to a reaction vessel as ring-opening polymerization initiators. Under nitrogen protection, the reaction system is heated to 110-130°C using a gradient heating method, and the reaction is carried out under constant reflux at this temperature for 6-10 hours. After the reaction is completed, the product is dissolved, precipitated, filtered, and dried to obtain the intermediate polycaprolactone-b-[1,3-bis(2-hydroxyethoxy)-2-nitrobenzene]-b-polycaprolactone.

[0013] Step B) Dissolve the intermediate in an anhydrous organic solvent, and slowly add methacryloyl chloride and triethylamine as an acid-binding agent dropwise under ice-water bath conditions of 0-10°C. After the addition is complete, remove the ice-water bath and continue stirring the reaction at room temperature for 20-28 hours. After the reaction is completed, wash, dry and rotary evaporate to remove the solvent in sequence to obtain the photocontrolled decrosslinking flexible oligomer.

[0014] Preferably, the preparation method of the photosensitive organosilicon acrylate interface agent includes:

[0015] Step C) Dissolve hydroxyl-terminated polydimethylsiloxane with a number average molecular weight of 800-1200 in tetrahydrofuran. Under nitrogen protection and stirring, add triethylamine as an acid-binding agent. Then, slowly add 2-nitrobenzoyl chloride at 20-30°C in a molar ratio of (0.9-1.1):1 to the hydroxyl-terminated polydimethylsiloxane, controlling the reaction to produce a mono-substituted product. After the addition is complete, continue the reaction at this temperature for 10-14 hours. After the reaction is complete, filter the solution and remove the solvent by rotary evaporation to obtain the intermediate product mono-nitrobenzoyloxy-mono-hydroxyl-terminated polydimethylsiloxane.

[0016] Step D) Dissolve the above intermediate product in dichloromethane, add triethylamine, add acryloyl chloride dropwise in an ice-water bath at 0-10°C, and react at this temperature for 4-8 hours to allow the remaining terminal hydroxyl groups to react with acryloyl chloride; after the reaction is completed, post-treatment is performed to obtain a structurally asymmetric photosensitive organosilicon acrylate interface agent.

[0017] Preferably, in step A), the mass ratio of 1,3-bis(2-hydroxyethoxy)-2-nitrobenzene, ε-caprolactone monomer, and catalyst is (14-16):(220-235):(0.08-0.12).

[0018] Preferably, in step B), the mass ratio of the intermediate, methacryloyl chloride and triethylamine is (240-250):(22-24):(14-16).

[0019] Preferably, in step C), the mass ratio of terminal hydroxyl polydimethylsiloxane, 2-nitrobenzoyl chloride and triethylamine is (45-55):(8-9):(3.5-4.5).

[0020] Preferably, the grinding and dispersing step grinds the mixture slurry to a fineness of no more than 5 micrometers; the viscosity adjustment step adjusts the viscosity of the ink base at 25°C to 2400-2600 mPa·s.

[0021] A peelable UV ink is also provided, characterized in that it is prepared by a peelable UV ink preparation method.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The prepared UV ink can form a protective film with excellent physical properties after initial curing. The ink film has high surface hardness and dense and stable structure, which can provide a strong physical barrier for the substrate and effectively resist scratches and wear that may be encountered in various processing processes. At the same time, it also exhibits excellent chemical resistance and can resist the erosion of various organic solvents. Thus, it ensures the integrity and cleanliness of the protected substrate surface in complex industrial environments and meets the stringent requirements of high-standard manufacturing processes for temporary protective coatings.

[0024] 2. Through ingenious molecular structure design, the cured ink film is endowed with a controllable state transformation capability. After fulfilling its protective mission, it only needs to be irradiated a second time with light of a specific wavelength to precisely trigger the structural transformation of the cross-linked network inside the ink film. This transforms the originally hard and brittle ink film into a flexible and elastic state on a macroscopic scale, and its elongation at break is greatly improved. This controllable transformation from a hard and brittle state to a flexible state is the key to enabling the ink film to be peeled off completely and without damage.

[0025] 3. It fundamentally solves the inherent contradiction in performance. Since its excellent peeling characteristics originate from the intrinsic chemical structure of the core functional components rather than added small molecule plasticizers, it completely avoids the risk of substrate surface contamination caused by plasticizer migration. After the peeling operation, the substrate surface can remain highly clean with no visible residues, eliminating the need for complex subsequent cleaning processes. It has significant application value for precision manufacturing fields such as optics and electronics, which have extremely high requirements for surface cleanliness, and significantly improves production efficiency and product yield. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] Example 1

[0028] This embodiment provides a method for preparing a peelable UV ink, comprising the following steps: pre-mixing a photocontrolled decrosslinking flexible oligomer, a photosensitive silicone acrylate interface agent, a multifunctional acrylate, a reactive diluent, a pigment, a photoinitiator, and additives in a mixing tank at room temperature to obtain a uniform slurry; grinding and dispersing the slurry to a predetermined fineness to obtain an ink base; adjusting the viscosity of the ink base, followed by vacuum degassing to eliminate bubbles, to obtain a peelable UV ink; in this embodiment, the multifunctional acrylate is a hexafunctional aliphatic polyurethane acrylate; the reactive diluent is trimethylolpropane triacrylate; the additives include leveling agents and defoamers; and by mass, the components are: 30 parts of the photocontrolled decrosslinking flexible oligomer, 15 parts of the hexafunctional aliphatic polyurethane acrylate, 10 parts of the trimethylolpropane triacrylate, 3 parts of the photosensitive silicone acrylate interface agent, 10 parts of the pigment, 6 parts of the photoinitiator, and 1 part of the additives.

[0029] The preparation method of the photocontrolled decrosslinking flexible oligomer includes: Step A) adding 1,3-bis(2-hydroxyethoxy)-2-nitrobenzene, ε-caprolactone monomer and catalyst as ring-opening polymerization initiators into a reaction vessel, wherein the mass ratio is 14:220:0.08; all raw materials can be obtained from commercial channels; under nitrogen protection, the reaction system is heated to 110°C by gradient heating, and the reaction is refluxed at this temperature for 10 hours; after the reaction, the product is cooled to room temperature, dissolved in a small amount of dichloromethane, and then slowly added dropwise to ten times the volume of cold methanol under vigorous stirring to precipitate, the precipitate is collected by filtration and placed in a vacuum drying oven to dry for 24 hours to obtain a white solid intermediate polycaprolactone-b-[1,3-bis(2-hydroxyethoxy)-2-nitrobenzene]-b-polycaprolactone, with a yield of 91.5%; Step B) adding the above The intermediate was dissolved in anhydrous dichloromethane. Methacrylamide chloride and triethylamine as an acid-binding agent were slowly added dropwise under an ice-water bath at 0°C, with a mass ratio of intermediate, methacrylamide chloride, and triethylamine of 240:22:14. Both methacrylamide chloride and triethylamine were commercially available analytical grade chemicals. After the addition was complete, the ice-water bath was removed, and the reaction was continued with stirring at room temperature for 28 hours. After the reaction, the organic phase was washed sequentially with dilute hydrochloric acid solution and saturated brine, dried over anhydrous magnesium sulfate, and filtered. The filtrate was then evaporated under reduced pressure to remove the solvent, yielding a pale yellow, viscous liquid, photocontrolled decrosslinking flexible oligomer with a yield of 89.2%. Fourier transform infrared spectroscopy revealed a C=O stretching vibration absorption peak at approximately 1725 cm⁻¹ and a C=C stretching vibration absorption peak at approximately 1638 cm⁻¹, indicating that the methacrylamide group had been successfully grafted to the end of the molecular chain.

[0030] The preparation method of the photosensitive organosilicon acrylate interface agent includes: Step C) dissolving hydroxyl-terminated polydimethylsiloxane with a number average molecular weight of 800 in tetrahydrofuran, adding triethylamine and 2-nitrobenzoyl chloride as acid-binding agents, wherein the mass ratio is 45:8:3.5; reacting at 20°C for 14 hours; after the reaction, filtering to remove triethylamine hydrochloride, concentrating the filtrate under reduced pressure, and separating and purifying by silica gel column chromatography to obtain a colorless, transparent, oily intermediate product, mono-nitrobenzoyloxy-mono-hydroxyl-terminated polydimethylsiloxane, with a yield of 78.3%; Step D) dissolving the above intermediate product in dichloromethane, adding triethylamine Acryloyl chloride was added dropwise in an ice-water bath at 0°C and reacted at this temperature for 8 hours to allow the remaining terminal hydroxyl groups to react with the acryloyl chloride. After the reaction, the product underwent post-treatment steps such as washing with dilute acid, washing with water, drying, and rotary evaporation to remove the solvent, resulting in a pale yellow, oily, asymmetric photosensitive organosilicon acrylate interface agent with a yield of 93.6%. The structure of the product was confirmed by ¹H-NMR spectroscopy, and the chemical shift matched the target structure. In the ink preparation, the grinding and dispersion step ground the mixture slurry to a fineness of no more than 5 micrometers. The viscosity adjustment step adjusted the viscosity of the ink base at 25°C to 2400 mPa·s.

[0031] The peelable UV ink prepared by the method in Example 1 has good hardness and solvent resistance after initial curing, making it suitable for temporary protection during the processing of precision components. For example, it can be used as a protective layer during semiconductor wafer dicing, effectively resisting coolant and physical impact. After being exposed to specific short-wave ultraviolet light, the ink film becomes flexible and can be completely peeled off from the wafer surface without any fragments or adhesive residue, ensuring the cleanliness requirements of subsequent processes.

[0032] Example 2

[0033] This embodiment provides a method for preparing a peelable UV ink. Its formula and preparation process parameters are basically the same as those in Example 1, except that the mass fractions of each component and the reaction conditions are adjusted. By mass fraction, the photocontrolled decrosslinking flexible oligomer is 35 parts, the hexafunctional aliphatic polyurethane acrylate is 20 parts, the trimethylolpropane triacrylate is 15 parts, the photosensitive organosilicon acrylate interface agent is 5 parts, the pigment is 15 parts, the photoinitiator is 8 parts, and the additives are 2 parts.

[0034] In the preparation of photocontrolled decrosslinking flexible oligomers, the mass ratio of initiator, monomer and catalyst in step A) is 15:228:0.1, the reaction temperature is 120°C and the reaction time is 8 hours; the mass ratio of intermediate, methacryloyl chloride and triethylamine in step B) is 245:23:15, the reaction temperature is 5°C and the reaction time is 24 hours.

[0035] In the preparation of photosensitive organosilicon acrylate interface agent, the number average molecular weight of the hydroxyl-terminated polydimethylsiloxane used is 1000, the raw material mass ratio in step C) is 50:8.5:4.0, the reaction temperature is 25°C, and the reaction time is 12 hours; the reaction temperature in step D) is 5°C, and the reaction time is 6 hours.

[0036] In ink preparation, the viscosity adjustment step adjusts the viscosity of the ink base to 2500 mPa·s at 25°C; all chemical raw materials are commercially available.

[0037] The peelable UV ink prepared by the method in Example 2 has a cured ink film that provides reliable protection while exhibiting balanced peel performance. It is suitable for manufacturing reusable photomasks, such as in the optical lens coating process. This ink can be used as a masking layer for non-coated areas. Its initial hardness is sufficient to withstand plasma cleaning, while it can be removed in one piece during peeling without damaging the precision coating on the lens surface, thus improving production efficiency and yield.

[0038] Example 3

[0039] This embodiment provides a method for preparing a peelable UV ink. Its formula and preparation process parameters are basically the same as those in Example 1, except that the mass fractions of each component and the reaction conditions are adjusted. By mass fraction, the photocontrolled decrosslinking flexible oligomer is 40 parts, the hexafunctional aliphatic polyurethane acrylate is 25 parts, the trimethylolpropane triacrylate is 20 parts, the photosensitive organosilicon acrylate interface agent is 7 parts, the pigment is 20 parts, the photoinitiator is 10 parts, and the additives are 3 parts.

[0040] In the preparation of photocontrolled decrosslinking flexible oligomers, the mass ratio of initiator, monomer and catalyst in step A) is 16:235:0.12, the reaction temperature is 130°C and the reaction time is 6 hours; the mass ratio of intermediate, methacryloyl chloride and triethylamine in step B) is 250:24:16, the reaction temperature is 10°C and the reaction time is 20 hours.

[0041] In the preparation of photosensitive organosilicon acrylate interface agent, the number average molecular weight of the hydroxyl-terminated polydimethylsiloxane used is 1200, the raw material mass ratio in step C) is 55:9:4.5, the reaction temperature is 30°C, and the reaction time is 10 hours; the reaction temperature in step D) is 10°C, and the reaction time is 4 hours.

[0042] In the ink preparation process, the viscosity adjustment step adjusts the viscosity of the ink base material to 2600 mPa·s at 25°C; the pigments (such as titanium dioxide) and additives (such as leveling agents and defoamers) used are all commercially available industrial-grade products.

[0043] The peelable UV ink prepared by the method in Example 3 has its hardness and chemical resistance further enhanced after initial curing, making it particularly suitable for harsh processing environments, such as chemical etching or sandblasting of metal parts, and providing solid protection for non-processed areas. During peeling, despite the high initial crosslinking density, it can still achieve effective decrosslinking under light irradiation, transforming into a flexible film with high elongation, ensuring complete peeling on substrates with complex morphology and avoiding cleaning difficulties caused by film breakage.

[0044] Example 4

[0045] This embodiment provides a method for preparing a peelable UV ink. Its formula and preparation process parameters are basically the same as those in Example 1, except that the mass fractions of each component and the reaction conditions are adjusted. By mass fraction, the photocontrolled decrosslinking flexible oligomer is 32 parts, the hexafunctional aliphatic polyurethane acrylate is 23 parts, the trimethylolpropane triacrylate is 18 parts, the photosensitive organosilicon acrylate interface agent is 4 parts, the pigment is 12 parts, the photoinitiator is 7 parts, and the additives are 1.5 parts.

[0046] In the preparation of photocontrolled decrosslinking flexible oligomers, the mass ratio of initiator, monomer, and catalyst in step A) is 14.5:225:0.09, the reaction temperature is 125°C, and the reaction time is 7 hours; the mass ratio of intermediate, methacryloyl chloride, and triethylamine in step B) is 242:22.5:14.5, the reaction temperature is 7°C, and the reaction time is 26 hours.

[0047] In the preparation of photosensitive organosilicon acrylate interface agent, the number average molecular weight of the hydroxyl-terminated polydimethylsiloxane used is 900, the raw material mass ratio in step C) is 48:8.2:3.8, the reaction temperature is 28°C, and the reaction time is 11 hours; the reaction temperature in step D) is 8°C, and the reaction time is 5 hours.

[0048] In ink preparation, the viscosity adjustment step adjusts the viscosity of the ink base at 25°C to 2450 mPa·s;

[0049] The peelable UV ink prepared by the method in Example 4, through formula adjustment, maintains a high initial hardness while improving the flexibility after decrosslinking. It is suitable for the manufacturing process of flexible electronic devices, such as as a temporary trace protection layer on flexible circuit boards. It can resist mechanical stress during bending and lamination, and can be peeled off by light, avoiding damage to the fragile substrate caused by traditional mechanical peeling or solvent cleaning.

[0050] Example 5

[0051] This embodiment provides a method for preparing a peelable UV ink. The formulation and preparation process parameters are basically the same as those in Example 1, except that the mass fractions of each component and the reaction conditions are adjusted. By mass fraction, the photocontrolled decrosslinking flexible oligomer is 38 parts, the hexafunctional aliphatic polyurethane acrylate is 18 parts, the trimethylolpropane triacrylate is 12 parts, the photosensitive organosilicon acrylate interface agent is 6 parts, the pigment is 18 parts, the photoinitiator is 9 parts, and the additives are 2.5 parts.

[0052] In the preparation of photocontrolled decrosslinking flexible oligomers, the mass ratio of initiator, monomer, and catalyst in step A) is 15.5:232:0.11, the reaction temperature is 115°C, and the reaction time is 9 hours; the mass ratio of intermediate, methacryloyl chloride, and triethylamine in step B) is 248:23.5:15.5, the reaction temperature is 3°C, and the reaction time is 22 hours.

[0053] In the preparation of photosensitive organosilicon acrylate interface agent, the number average molecular weight of the hydroxyl-terminated polydimethylsiloxane used is 1100, the raw material mass ratio in step C) is 52:8.8:4.2, the reaction temperature is 22°C, and the reaction time is 13 hours; the reaction temperature in step D) is 2°C, and the reaction time is 7 hours.

[0054] In ink preparation, the viscosity adjustment step adjusts the viscosity of the ink base at 25°C to 2550 mPa·s;

[0055] The peelable UV ink prepared by the method in Example 5 has a high content of photosensitive components in its formulation, which makes it more sensitive to the peel signal (short-wave UV) and requires less peel energy. It is suitable for energy-sensitive substrates, such as in the manufacture of biochips or microfluidic devices, where it can be used as a sealing layer for temporary channels. Its gentle peeling process will not affect the bioactive substances fixed on the substrate due to thermal effects or high-intensity light.

[0056] Comparative Example 1

[0057] This comparative example uses a method from the prior art of improving ink brittleness by physically adding plasticizers. The ink components, by weight, include: 55 parts of hexafunctional aliphatic polyurethane acrylate, 20 parts of trimethylolpropane triacrylate, 15 parts of pigment, 8 parts of photoinitiator, and 2 parts of additives. In the above base ink, an additional 15 parts of dioctyl phthalate (DOP) are added as a plasticizer. All these raw materials are commercially available industrial products. The preparation process involves mixing all components evenly in a mixing tank, grinding them to a fineness of no more than 5 micrometers using a three-roll mill, adjusting the viscosity, and then degassing to obtain the final ink.

[0058] Performance testing

[0059] The inks prepared in Examples 1-5 and Comparative Example 1 were uniformly coated onto quartz glass slides and cured by UV irradiation with a UV lamp of 365 nm at an energy of 1000 mJ / cm². The cured ink films of Examples 1-5 were then irradiated with a UV lamp of 300 nm at an energy of 1500 mJ / cm². Performance tests were then conducted on all samples. The specific test items and methods are as follows:

[0060] Initial hardness test: According to GB / T6739-2006 standard, the hardness of the ink film after initial curing was tested using the pencil hardness method;

[0061] Solvent resistance test: Using a cotton cloth soaked in methyl ethyl ketone (MEK), the surface of the ink film after initial curing was repeatedly wiped under a 1kg load, and the number of wiping cycles when the ink film was damaged was recorded.

[0062] Peeling performance test: Use tweezers to try to peel the ink film from the substrate from the edge of the ink film, and observe the continuity and integrity of the peeling process;

[0063] Observation of peeling residue: After the ink film is peeled off, observe whether there are any residues on the surface of the substrate using a 200x optical microscope;

[0064] Mechanical property transformation test: For the ink film of the example, the Young's modulus and elongation at break of the region before and after 300nm UV irradiation were tested using a tensile testing machine.

[0065] Test Results

[0066] The performance test results of each embodiment and comparative example are summarized in the table below;

[0067] Test item Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Initial hardness (pencil hardness) 2H 3H 3H 3H 2H HB Number of times of resistance to MEK wiping >200 >200 >200 >200 >200 <30 Peeling performance Complete whole sheet peeling Complete whole sheet peeling Complete whole sheet peeling Complete whole sheet peeling Complete whole sheet peeling Severe fragmentation, cannot peel whole sheet Residual on substrate surface after peeling No visible residual No visible residual No visible residual No visible residual No visible residual A large amount of fine residual Young's modulus (before irradiation) 1.4 GPa 1.5 GPa 1.6 GPa 1.5 GPa 1.4 GPa 0.4 GPa Young's modulus (after irradiation) 0.3 GPa 0.2 GPa 0.2 GPa 0.2 GPa 0.3 GPa - Elongation at break (after irradiation) 195% 210% 225% 215% 205% -

[0068] As can be seen from the test results in the table above, the peelable UV ink preparation method provided in Examples 1-5 of this invention produces inks that exhibit high initial hardness (2H-3H) and excellent solvent resistance (resistance to more than 200 MEK wiping cycles) after initial curing. This indicates that the ink film is reliable as a protective layer. After short-wave UV irradiation, the Young's modulus of the ink film decreases significantly, while the elongation at break increases substantially, macroscopically showing that the ink film changes from a hard and brittle state to a flexible state. Therefore, during peeling, the ink film can be easily peeled off from the substrate in a complete sheet, with no visible residue on the substrate surface.

[0069] In contrast, Comparative Example 1 uses existing technology. Although adding plasticizers reduces the brittleness of the ink film, it also severely sacrifices its working performance. Its initial hardness is only HB, and its solvent resistance is poor, which cannot meet the protection requirements in most industrial processes. More importantly, during peeling, its ink film still breaks severely, making it impossible to peel off the whole sheet, and leaving a large amount of hard-to-clean residue on the substrate surface, which is unacceptable in the field of precision manufacturing.

[0070] In summary, this invention introduces photoresponsive groups into the crosslinking network and interface layer through molecular-level structural design. During use, the high crosslinking density ensures the hardness and chemical resistance of the ink film. When peeling is required, a specific light signal is used to precisely reduce the crosslinking density and interface adhesion, thus achieving a balance between working performance and clean peeling performance and resolving the inherent contradictions in the prior art.

[0071] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments that can be applied to other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing a peelable UV ink, characterized in that, Includes the following steps: The photo-controlled decrosslinking flexible oligomer, photosensitive organosilicon acrylate interface agent, multifunctional acrylate, reactive diluent, pigment, photoinitiator and additives are stirred and premixed in a mixing tank at room temperature to obtain a uniform slurry. The mixed slurry is ground and dispersed to a predetermined fineness to obtain the ink base material; The viscosity of the ink base is adjusted, followed by vacuum degassing to eliminate air bubbles, resulting in a peelable UV ink.

2. The method for preparing a peelable UV ink according to claim 1, characterized in that, The multifunctional acrylate is a hexafunctional aliphatic polyurethane acrylate; the reactive diluent is trimethylolpropane triacrylate; the additives include leveling agents and defoamers.

3. The method for preparing a peelable UV ink according to claim 2, characterized in that, By weight, the composition is as follows: 30-40 parts of photocontrolled decrosslinking flexible oligomer, 15-25 parts of hexafunctional aliphatic polyurethane acrylate, 10-20 parts of trimethylolpropane triacrylate, 3-7 parts of photosensitive organosilicon acrylate interface agent, 10-20 parts of pigment, 6-10 parts of photoinitiator, and 1-3 parts of additives.

4. The method for preparing a peelable UV ink according to claim 1, characterized in that, The preparation methods of photocontrolled decrosslinking flexible oligomers include: Step A) 1,3-bis(2-hydroxyethoxy)-2-nitrobenzene, ε-caprolactone monomer, and organotin catalyst, which serve as ring-opening polymerization initiators, are added to a reaction vessel. Under nitrogen protection, the reaction system is heated to 110-130°C using a gradient heating method, and then refluxed at this temperature for 6-10 hours. After the reaction is completed, the product is dissolved, precipitated, filtered, and dried to obtain the intermediate polycaprolactone-b-[1,3-bis(2-hydroxyethoxy)-2-nitrobenzene]-b-polycaprolactone. Step B) Dissolve the intermediate in an anhydrous organic solvent, and slowly add methacryloyl chloride and triethylamine as an acid-binding agent dropwise under ice-water bath conditions of 0-10°C. After the addition is complete, remove the ice-water bath and continue stirring the reaction at room temperature for 20-28 hours. After the reaction is completed, wash, dry and rotary evaporate to remove the solvent in sequence to obtain the photocontrolled decrosslinking flexible oligomer.

5. The method for preparing a peelable UV ink according to claim 1, characterized in that, The preparation methods of photosensitive organosilicon acrylate interface agents include: Step C) Dissolve hydroxyl-terminated polydimethylsiloxane with a number average molecular weight of 800-1200 in tetrahydrofuran. Under nitrogen protection and stirring, add triethylamine as an acid-binding agent. Then, slowly add 2-nitrobenzoyl chloride at 20-30°C in a molar ratio of (0.9-1.1):1 to the hydroxyl-terminated polydimethylsiloxane, controlling the reaction to produce a mono-substituted product. After the addition is complete, continue the reaction at this temperature for 10-14 hours. After the reaction is complete, filter the solution and remove the solvent by rotary evaporation to obtain the intermediate product mono-nitrobenzoyloxy-mono-hydroxyl-terminated polydimethylsiloxane. Step D) Dissolve the above intermediate product in dichloromethane, add triethylamine, add acryloyl chloride dropwise in an ice-water bath at 0-10°C, and react at this temperature for 4-8 hours to allow the remaining terminal hydroxyl groups to react with acryloyl chloride; after the reaction is completed, post-treatment is performed to obtain a structurally asymmetric photosensitive organosilicon acrylate interface agent.

6. The method for preparing a peelable UV ink according to claim 4, characterized in that, In step A), the mass ratio of 1,3-bis(2-hydroxyethoxy)-2-nitrobenzene, ε-caprolactone monomer, and catalyst is (14-16):(220-235):(0.08-0.12).

7. The method for preparing a peelable UV ink according to claim 4, characterized in that, In step B), the mass ratio of the intermediate, methacryloyl chloride, and triethylamine is (240-250):(22-24):(14-16).

8. The method for preparing a peelable UV ink according to claim 5, characterized in that, In step C), the mass ratio of terminal hydroxyl polydimethylsiloxane, 2-nitrobenzoyl chloride, and triethylamine is (45-55):(8-9):(3.5-4.5).

9. The method for preparing a peelable UV ink according to claim 1, characterized in that, The grinding and dispersing step grinds the mixture slurry to a fineness of no more than 5 micrometers; the viscosity adjustment step adjusts the viscosity of the ink base at 25°C to 2400-2600 mPa·s.

10. A peelable UV ink, characterized in that, It is prepared by the method for preparing a peelable UV ink according to any one of claims 1-9.