Preparation method of UV ink with good adhesive force
Through unique formulation and pretreatment processes, UV inks form strong chemical bonding and mechanical interlocking on non-polar and metal substrates, solving the problem of insufficient adhesion and achieving high adhesion and low energy consumption UV ink preparation.
Patent Information
- Application Number
- CN202510698530.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-28
- Publication Date
- 2025-08-15
AI Technical Summary
The existing UV inks have shortcomings in adhesion performance, especially on non-polar substrates and metal substrates, the existing improvement methods are unstable in effect and increase production costs, and traditional methods affect other performances or require special equipment.
The substrate is pretreated with a unique formulation design, including a prepolymer system, a monomer system, a photoinitiator and a functional additive, combined with a β-cyclodextrin modified silane coupling agent, and the adhesion is enhanced through chemical bonding and mechanical interlocking, and the coating density is enhanced using microencapsulated metal salts and nanosilica, and the curing process is optimized.
It significantly improves the adhesion level of UV ink, reduces curing energy, improves durability and mechanical properties, and is suitable for a variety of substrates.
Smart Images
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Abstract
Description
Technical Field
[0001] The invention relates to the field of UV ink, and in particular to a method for preparing UV ink with good adhesion. Background Art
[0002] Ultraviolet (UV) curing inks, as environmentally friendly inks, have been widely used in printing and packaging, electronics, automotive coatings, and other fields in recent years due to their advantages such as fast curing speed, low volatile organic compound (VOC) emissions, and low energy consumption. However, traditional UV inks still face many technical bottlenecks in practical applications, especially in terms of adhesion performance.
[0003] The adhesion issues of currently available UV inks are primarily manifested in the following aspects: First, due to surface energy differences and a lack of reactive groups, the inks struggle to form a strong bond with non-polar substrates (such as polyethylene and polypropylene) and metal substrates, making them susceptible to shedding. Second, existing technologies often use physical methods such as roughening or corona treatment to improve adhesion, but these methods are unstable and increase production costs. Regarding chemical modification, while commonly used silane coupling agents can improve interfacial bonding, their single function is insufficient to meet high adhesion requirements. Furthermore, the shrinkage stress generated during the curing process of traditional UV inks can cause microcracks between the coating and the substrate, further weakening adhesion.
[0004] In terms of formulation design, existing technologies typically improve performance by increasing the prepolymer content or adding adhesion promoters, but this often affects other ink properties. For example, while excessive use of epoxy acrylate can improve adhesion, it can also lead to increased coating brittleness; while some adhesion promoters may be incompatible with the system, causing storage stability issues.
[0005] Existing methods for substrate pretreatment primarily include plasma treatment and flame treatment. These methods require specialized equipment, and the surface activity of the treated substrate decreases over time. Therefore, developing a simple, cost-effective UV ink with long-lasting high adhesion and its associated treatment methods has become a pressing technical challenge in this field. Summary of the Invention
[0006] The main purpose of the present invention is to provide a method for preparing UV ink with good adhesion, which can effectively solve the problems in the background technology.
[0007] To achieve the above object, the technical solution adopted by the present invention is: A method for preparing UV ink with good adhesion, comprising the following components in percentage by mass: Prepolymer system: mixture of polyurethane acrylate and epoxy acrylate 38% to 52%; Monomer system: Acrylate monomer, including: 0.5% to 2.0% of methacrylated dopamine containing a catechol group, 3.0% to 8.0% of adamantyl-modified acrylate monomer, 12% to 20% of isobornyl acrylate, and 12% to 20% of tripropylene glycol diacrylate; Photoinitiator: mixed initiator, including: 2.0% to 4.5% 2,4,6-trimethylbenzoylphenylphosphine oxide, 1.5% to 3.5% 2-methyl-1-(4-methylthiophenyl)-2-morpholinyl-1-propanone; Functional additives: additives, including: microencapsulated metal salt 0.1% to 0.5%, fluorinated surfactant 0.3% to 1.0%, nano-silica 1.0% to 3.0%, and polymerization inhibitor 0.1% to 0.3%; Optional pigments: 5% organic or inorganic pigments.
[0008] Preferably, in the prepolymer system, the mass ratio of polyurethane acrylate to epoxy acrylate is 2:1.
[0009] Preferably, the adamantyl-modified acrylate monomer is adamantane methacrylate or adamantane ethyl acrylate; The microencapsulated metal salt is one of iron acetylacetonate or copper acetylacetonate, and has a particle size of 30-80 nm; The fluorine-containing surfactant is one of perfluoropolyether acrylate or fluorocarbon-modified silicone; The polymerization inhibitor is one of p-methoxyphenol or hydroquinone; The nano-silica is hydrophobic fumed silica and has a specific surface area of 150-250 m² / g.
[0010] A method for preparing the above-mentioned UV ink comprises the following steps: Step 101, pre-dispersion: microencapsulated metal salt, nano silicon dioxide and Mix with high-quality tripropylene glycol diacrylate and grind to a fineness of ≤5μm; Step 102: Mix the main ingredients: Add polyurethane acrylate, epoxy acrylate, Isobornyl acrylate, remaining Tripropylene glycol diacrylate, methacrylated dopamine containing a catechol group, and adamantyl-modified acrylate monomers were placed in a 40°C constant temperature water bath with a frame-type stirring blade (500 rpm, 30 minutes) and vacuum degassing (-0.08 MPa, 10 minutes) to remove dissolved air; Step 103, adding auxiliary agents: adding fluorinated surfactant and polymerization inhibitor, and dispersing in a high-speed disperser (1200 rpm, 15 minutes) until the system has no visible particles, and performing a secondary vacuum degassing (-0.09 MPa, 20 minutes) and storing in a dark place; Step 104: Adding photoinitiator: dissolve 2,4,6-trimethylbenzoylphenylphosphine oxide and 2-methyl-1-(4-methylthiophenyl)-2-morpholinyl-1-propanone in the remaining Add the main material system to isobornyl acrylate, stir at 300 rpm for 15 minutes, filter through a 400-mesh stainless steel filter, and adjust the viscosity to 300-600 mPa·s; Step 105, dispersion grinding: add pigment, mechanically stir at a speed of 2500 rpm for 40 minutes, and then grind to a scraper fineness of ≤10 μm to obtain the UV ink. Preferably, when the microencapsulated metal salt is ferric acetylacetonate, the preparation method of the metallized microcapsules is as follows: Ferric acetylacetonate was dissolved in anhydrous ethanol, and hexadecyltrimethylammonium bromide was added. The mixture was ultrasonically treated (40 kHz, 30 minutes) to form a uniform dispersion. Ethyl orthosilicate and ammonia water were slowly added under stirring (500 rpm). The mixture was reacted at 50°C for 6 hours. The ethyl orthosilicate was hydrolyzed and condensed to form a SiO2 coating layer. The coating thickness was controlled by adjusting the amount of ethyl orthosilicate (target: 30-50 nm). The reaction solution was centrifuged (8000 rpm, 10 minutes) and washed three times with anhydrous ethanol to remove unreacted products. The mixture was then vacuum dried at 60°C for 12 hours to obtain brown powder microcapsules.
[0011] Preferably, the mass ratio of the ethyl orthosilicate to ferric acetylacetonate is 4:1, and the concentration of the cetyltrimethylammonium bromide used is 0.5% (w / v).
[0012] The present invention also discloses a method for curing the UV ink, which comprises the following steps: Step 201: reacting β-cyclodextrin with isocyanatepropyltriethoxysilane in a polar solvent to generate a cyclodextrin-silane coupling agent, mixing the coupling agent with ethanol and an acidic catalyst, ultrasonically dispersing the mixture, and then aging the mixture to obtain a substrate pretreatment solution; Step 202: spray the pretreatment liquid onto the substrate, bake at 100°C for 5 minutes, apply the ink onto the pretreated substrate, and cure it sequentially using a dual-wavelength UV light source of 365nm and 395nm, with curing energies of 200-300mJ / cm² and 800-1200mJ / cm², respectively. Step 203: 60℃ hot air circulation for 2 minutes to complete the curing Preferably, the specific preparation method of the substrate pretreatment liquid is: Mix 20% β-cyclodextrin, 9% isocyanatepropyltriethoxysilane, and 71% N,N-dimethylformamide in a mass ratio, and stir at 80°C under nitrogen with magnetic stirring (300 rpm) for 12 hours. Pour the reaction solution into icy ether for precipitation, vacuum filter, and dry at 60°C for 24 hours to obtain a white powder, which is the β-cyclodextrin modified silane coupling agent. The obtained β-cyclodextrin modified silane coupling agent (0.8%), acetic acid (0.5%), and anhydrous ethanol (98.7%) were mixed, and then dispersed by 40 kHz ultrasonic treatment for 30 minutes (power density 0.5 W / cm³). The mixture was allowed to stand at 25° C. in the dark for 24 hours to form a transparent sol to obtain the substrate pretreatment solution.
[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention significantly improves the comprehensive performance of UV ink through unique formula design and process optimization. First, the substrate is pretreated with a β-cyclodextrin-modified silane coupling agent. Its cavity structure can selectively adsorb the adamantyl monomer in the ink, and convert the supramolecular effect into a covalent bond network during the curing process, so that the ink and the substrate form a strong chemical bond. At the same time, the microencapsulated metal salt releases metal ions during curing, forms coordination bonds with the catechol groups in the ink, and mechanically interlocks with the substrate through the SiO2 shell. The dual effect greatly improves the adhesion. Test results show that the adhesion level reaches level 0-1. In addition, the dual-wavelength UV curing process combined with the delayed release effect of the microencapsulated metal salt achieves efficient curing and deep cross-linking, reducing the curing energy to 300mJ / cm².
[0014] 2. In terms of durability and mechanical properties, the synergistic effect of nano-silica and metal salts enhances the coating's compactness, resulting in excellent weather and chemical resistance. After 500 hours of aging, the color difference (ΔE) is only 0.8. The optimal ratio of polyurethane acrylate to epoxy acrylate in the prepolymer system (2:1) balances flexibility and rigidity. Combined with the compliant chain segments of isobornyl acrylate, the coating not only passes a 1mm mandrel bend test but also achieves a pencil hardness of 5H. The addition of a fluorosurfactant further optimizes interfacial properties, ensuring uniform ink spreading. These innovative features contribute to the outstanding adhesion, curing efficiency, and durability of this UV ink, promising broad application prospects. DETAILED DESCRIPTION
[0015] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.
[0016] The present invention discloses a UV ink with good adhesion, which comprises the following components in percentage by mass: Prepolymer system: mixture of polyurethane acrylate and epoxy acrylate 38% to 52%; Monomer system: Acrylate monomers, including: 0.5% to 2.0% methacrylated dopamine containing catechol group, 3.0% to 8.0% adamantyl modified acrylate monomer, 12% to 20% isobornyl acrylate, and 12% to 20% tripropylene glycol diacrylate; Photoinitiator: mixed initiator, including: 2.0% to 4.5% 2,4,6-trimethylbenzoylphenylphosphine oxide, 1.5% to 3.5% 2-methyl-1-(4-methylthiophenyl)-2-morpholinyl-1-propanone; Functional additives: additives, including: microencapsulated metal salt 0.1% to 0.5%, fluorinated surfactant 0.3% to 1.0%, nano-silica 1.0% to 3.0%, and polymerization inhibitor 0.1% to 0.3%; Optional pigments: 5% organic or inorganic pigments.
[0017] In the prepolymer system, the mass ratio of polyurethane acrylate to epoxy acrylate is 2:1, the adamantyl-modified acrylate monomer is adamantane methacrylate or adamantane ethyl acrylate; the microencapsulated metal salt is one of ferric acetylacetonate or copper acetylacetonate, with a particle size of 30-80 nm, and the coating material is one of silica or polyvinyl alcohol; the fluorine-containing surfactant is one of perfluoropolyether acrylate or fluorocarbon-modified silicone; the polymerization inhibitor is one of p-methoxyphenol or hydroquinone; and the nano-silica is hydrophobic fumed silica with a specific surface area of 150-250 m² / g.
[0018] The inventors also proposed a pre-treatment liquid for treating the substrate before curing the above-mentioned UV ink, and the specific preparation method thereof is as follows: Mix 20% β-cyclodextrin, 9% isocyanatepropyltriethoxysilane, and 71% N,N-dimethylformamide in a mass ratio, and stir at 80°C under nitrogen with magnetic stirring (300 rpm) for 12 hours. Pour the reaction solution into icy ether for precipitation, vacuum filter, and dry at 60°C for 24 hours to obtain a white powder, which is the β-cyclodextrin modified silane coupling agent. The obtained β-cyclodextrin modified silane coupling agent (0.8%), acetic acid (0.5%), and anhydrous ethanol (98.7%) were mixed, and then dispersed by 40 kHz ultrasonic treatment for 30 minutes (power density 0.5 W / cm³). The mixture was allowed to stand at 25° C. in the dark for 24 hours to form a transparent sol to obtain the substrate pretreatment solution.
[0019] The inventors found during the research process that: The β-cyclodextrin-modified silane coupling agent (CD-PTES) in the pretreatment solution forms an interfacial layer rich in cyclodextrin cavities on the substrate surface through hydrolysis and condensation. These cavities selectively adsorb adamantyl monomers (such as adamantane methacrylate) in the ink, forming a host-guest inclusion complex. Chemical formula: During UV curing, the acrylate group of the adamantyl monomer participates in the polymerization reaction, converting the supramolecular effect into a covalent bond network, so that the pretreatment layer forms a chemical bond with the main body of the ink: The rigid ring structure of cyclodextrin can absorb the curing shrinkage stress, and its polyhydroxy shell forms a hydrogen bond network with the substrate, further dispersing the interfacial stress (molecular dynamics simulation shows that the stress dispersion efficiency is improved by 40%).
[0020] In addition, the inventors have also added microencapsulated metal salts in the present invention: the metal salt is specifically one of ferric acetylacetonate or copper acetylacetonate, the only difference being that ferric acetylacetonate or copper acetylacetonate provides Fe in the system. 3+ or Cu 2+ Therefore, in the present invention, iron acetylacetonate or copper acetylacetonate can be used interchangeably.
[0021] The following describes the preparation method of metallized microcapsules using ferric acetylacetonate as an example of microencapsulated metal salt: Ferric acetylacetonate was dissolved in anhydrous ethanol, and hexadecyltrimethylammonium bromide was added. The mixture was ultrasonically treated (40 kHz, 30 minutes) to form a uniform dispersion. Ethyl orthosilicate and ammonia water were slowly added under stirring (500 rpm). The mixture was reacted at 50°C for 6 hours. The ethyl orthosilicate was hydrolyzed and condensed to form a SiO2 coating layer. The coating thickness was controlled by adjusting the amount of ethyl orthosilicate (target: 30-50 nm). The reaction solution was centrifuged (8000 rpm, 10 minutes) and washed three times with anhydrous ethanol to remove unreacted products. The mixture was then vacuum dried at 60°C for 12 hours to obtain brown powder microcapsules.
[0022] In this method, the mass ratio of ethyl orthosilicate to ferric acetylacetonate is 4:1, the concentration of cetyltrimethylammonium bromide used is 0.5% (w / v), and the specific amount of anhydrous ethanol used only needs to be sufficient to allow the ferric acetylacetonate to be completely dissolved.
[0023] The present inventors have found that the addition of microencapsulated metal salts has the following mechanism of action: 1. When UV ink is cured, the acrylic acid monomer generated in the system locally reduces the pH, generally reaching pH <5. At this time, the SiO2 shell slowly dissolves and releases , released Combined with the catechol group in methacrylated dopamine containing catechol groups to form a strong coordination bond: 2. Microcapsules (50 nm) are enriched at the ink-substrate interface, and form silicon-oxygen bonds (Si-OM, M = substrate metal or silanol group) with the substrate hydroxyl group through the SiO2 shell to achieve mechanical interlocking.
[0024] 3. It can slightly inhibit premature surface curing, allowing deep initiators (such as TPO) more time to penetrate the micropores of the substrate and improve the degree of interfacial crosslinking.
[0025] The present invention is further disclosed below in conjunction with the embodiments: Example 1 In this example, the raw materials of each component are prepared according to the following mass percentages: Prepolymer system: mixture of polyurethane acrylate and epoxy acrylate 38; Monomer system: Acrylate monomers, including: 2.0% methacrylated dopamine containing catechol group, 8.0% adamantane methacrylate, 20% isobornyl acrylate, and 20% tripropylene glycol diacrylate; Photoinitiator: Mixed initiator, including: 2,4,6-trimethylbenzoylphenylphosphine oxide 4%, 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone 1.5%; Functional additives: additives 4% to 8%, including: microencapsulated ferric acetylacetonate 0.1%, perfluoropolyether acrylate 0.3%, hydrophobic fumed nanosilica 1.0%, and p-methoxyphenol 0.1%; Pigment: 5% Phthalocyanine Blue BGS.
[0026] After preparing the raw materials, prepare UV ink according to the following steps: Step 101, pre-dispersion: microencapsulated ferric acetylacetonate, hydrophobic fumed nano-silica and Mix with high-quality tripropylene glycol diacrylate and grind to a fineness of ≤5μm; Step 102: Mix the main ingredients: Add polyurethane acrylate, epoxy acrylate, Isobornyl acrylate, residual Tripropylene glycol diacrylate, methacrylated dopamine containing catechol groups, and adamantane methacrylate were placed in a constant temperature water bath at 40°C with a frame-type stirring blade (500 rpm, 30 minutes) and vacuum degassing (-0.08 MPa, 10 minutes) to remove dissolved air; Step 103, adding auxiliary agents: adding perfluoropolyether acrylate and p-methoxyphenol, and dispersing in a high-speed disperser (1200 rpm, 15 minutes) until no particles are visible to the naked eye, and performing a secondary vacuum degassing (-0.09 MPa, 20 minutes) and storing in a dark place; Step 104: Adding photoinitiator: dissolve 2,4,6-trimethylbenzoylphenylphosphine oxide and 2-methyl-1-(4-methylthiophenyl)-2-morpholinyl-1-propanone in the remaining Add the main material system to isobornyl acrylate, stir at 300 rpm for 15 minutes, filter through a 400-mesh stainless steel filter, and adjust the viscosity to 300-600 mPa·s; Step 105, dispersion grinding: adding pigment, mechanically stirring at a rotation speed of 2500 rpm for 40 minutes, and then grinding to a scraper fineness of ≤10 μm to obtain the UV ink.
[0027] Example 2 This embodiment is different from embodiment 1 only in that the mass percentages of the components are adjusted. The specific components, preparation steps, and specific parameters involved in the preparation steps are the same as those in embodiment 1. The mass percentages of the components are as follows: In this example, the raw materials of each component are prepared according to the following mass percentages: Prepolymer system: mixture of polyurethane acrylate and epoxy acrylate 52%; Monomer system: Acrylate monomers, including: 0.5% methacrylated dopamine containing catechol group, 3.0% adamantane methacrylate, 20% isobornyl acrylate, and 12% tripropylene glycol diacrylate; Photoinitiator: Mixed initiator, containing: 2,4,6-trimethylbenzoylphenylphosphine oxide 2.0%, 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone 3.5%; Functional additives: additives, including: microencapsulated ferric acetylacetonate 0.5%, perfluoropolyether acrylate 0.3%, hydrophobic fumed nanosilica 1.0%, p-methoxyphenol 0.2%; Pigment: 5% Phthalocyanine Blue BGS.
[0028] Example 3 This embodiment is different from embodiment 1 only in that the mass percentages of the components are adjusted. The specific components, preparation steps, and specific parameters involved in the preparation steps are the same as those in embodiment 1. The mass percentages of the components are as follows: In this example, the raw materials of each component are prepared according to the following mass percentages: Prepolymer system: 45% mixture of polyurethane acrylate and epoxy acrylate; Monomer system: Acrylate monomers, including: 1.5% methacrylated dopamine containing catechol group, 6% adamantane methacrylate, 15.5% isobornyl acrylate, and 18.5% tripropylene glycol diacrylate; Photoinitiator: Mixed initiator, including: 2,4,6-trimethylbenzoylphenylphosphine oxide 3.0%, 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone 2.5%; Functional additives: additives, including: microencapsulated ferric acetylacetonate 0.3%, perfluoropolyether acrylate 0.5%, hydrophobic fumed nanosilica 2.0%, p-methoxyphenol 0.2%; Pigment: 5% Phthalocyanine Blue BGS.
[0029] Example 4 This embodiment is different from embodiment 1 only in that the mass percentages of the components are adjusted. The specific components, preparation steps, and specific parameters involved in the preparation steps are the same as those in embodiment 1. The mass percentages of the components are as follows: In this embodiment, the raw materials of each component are prepared according to the following mass percentages: Prepolymer system: mixture of polyurethane acrylate and epoxy acrylate 47.5%; Monomer system: Acrylate monomers, including: 1.5% methacrylated dopamine containing catechol group, 6% adamantane methacrylate, 12% isobornyl acrylate, and 15.8% tripropylene glycol diacrylate; Photoinitiator: Mixed initiator, including: 2,4,6-trimethylbenzoylphenylphosphine oxide 4.5%, 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone 3%; Functional additives: additives, including: microencapsulated ferric acetylacetonate 0.4%, perfluoropolyether acrylate 1.0%, hydrophobic fumed nanosilica 3.0%, p-methoxyphenol 0.3%; Pigment: 5% Phthalocyanine Blue BGS.
[0030] Example 5 This embodiment is different from embodiment 1 only in that the mass percentages of the components are adjusted. The specific components, preparation steps, and specific parameters involved in the preparation steps are the same as those in embodiment 1. The mass percentages of the components are as follows: In this example, the raw materials of each component are prepared according to the following mass percentages: Prepolymer system: 50% mixture of polyurethane acrylate and epoxy acrylate; Monomer system: Acrylate monomers, including: 1.8% methacrylated dopamine containing catechol group, 4.2% adamantane methacrylate, 17% isobornyl acrylate, and 13% tripropylene glycol diacrylate; Photoinitiator: Mixed initiator, including: 2,4,6-trimethylbenzoylphenylphosphine oxide 3.5%, 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone 3%; Functional additives: additives, including: microencapsulated ferric acetylacetonate 0.4%, perfluoropolyether acrylate 0.6%, hydrophobic fumed nanosilica 1.3%, p-methoxyphenol 0.2%; Pigment: 5% Phthalocyanine Blue BGS.
[0031] Comparative Example 1 In this comparative example, based on Example 3, adamantane methacrylate was replaced with adamantane ethyl acrylate, and the remaining components, proportions, preparation steps, and specific parameters involved in the preparation steps were the same as those in Example 1.
[0032] Comparative Example 2 In this comparative example, based on Example 3, microencapsulated ferric acetylacetonate was replaced with microencapsulated copper acetylacetonate, and the remaining components, proportions, preparation steps, and specific parameters involved in the preparation steps were the same as those in Example 1.
[0033] Comparative Example 3 In this comparative example, based on Example 3, perfluoropolyether acrylate was used to replace fluorocarbon-modified silicone, and p-methoxyphenol was replaced by hydroquinone. The remaining components, proportions, preparation steps, and specific parameters involved in the preparation steps were the same as those in Example 1.
[0034] Comparative Example 4 This comparative example is based on Example 3, except that no microencapsulated metal salt is added to the raw materials, the remaining raw materials and component ratios remain unchanged, and the preparation steps and specific parameters involved in the preparation steps are the same as those in Example 1.
[0035] The UV ink samples prepared in Examples 1-5 and Comparative Examples 1-4 were taken and the inks prepared in Examples 1-5 and Comparative Examples 1-3 were cured on the surface of the aluminum alloy plate treated with electrophoretic paint using the following scheme: The pretreatment liquid is sprayed on the substrate and baked at 100°C for 5 minutes. The ink is then coated on the pretreated substrate and cured by dual-wavelength UV light sources of 365nm and 395nm, with curing energies of 200-300mJ / cm² and 800-1200mJ / cm² respectively; hot air circulation at 60°C for 2 minutes completes the curing.
[0036] The ink prepared in Comparative Example 4 was cured on the surface of the aluminum alloy plate treated with electrophoretic paint using the following scheme: No pre-treatment liquid is used to treat the substrate. Direct curing is done using a 395nm wavelength UV light source with a curing energy of 800-1200mJ / cm² and hot circulating air for 2 minutes.
[0037] Take the aluminum alloy plate treated with electrophoretic paint after the above UV ink is cured and perform the following tests: The UV inks prepared in Examples 1-5 and Comparative Examples 1-4 were tested for performance according to the test methods in the above table. The results are as follows: 3. Results Analysis 1. Adhesion performance Best performance: Examples 1-5 and Comparative Example 2 all achieved 0-1 level (excellent), which was attributed to the conversion of the supramolecular interaction between the adamantyl monomer and the β-cyclodextrin pretreatment layer into a covalent bond (chemical bond). 3+ / Cu 2+ ) and the coordination bonds with the catechol groups enhance the interfacial bonding.
[0038] Worst performance: Comparative Example 4 (level 4), due to the lack of microencapsulated metal salt and pretreatment steps, the interface binding only relies on physical adsorption.
[0039] 2. Curing efficiency Example 3 achieved the lowest cure energy (300 mJ / cm²), thanks to the synergistic effect of the photoinitiators (TPO + 907). The microencapsulated metal salt delayed surface cure and promoted deep crosslinking. Comparative Example 4, lacking pretreatment and metal salt, achieved a significantly higher cure energy (600 mJ / cm²).
[0040] 3. Weather resistance and solvent resistance Example 3 had the lowest ΔE (0.8) because its nanosilica (2.0%) and microencapsulated metal salt (0.3%) optimized the crosslinking density. Comparative Example 3 had poor solvent resistance due to poor compatibility of the fluorocarbon-modified silicone with the system, resulting in surface defects.
[0041] 4. Comparison of Proportional Differences Comparative Example 1: The steric hindrance of adamantane ethyl acrylate increased, resulting in a slight decrease in adhesion (level 1).
[0042] Comparative Example 2: Copper acetylacetonate replaces iron, with similar performance but slightly inferior weather resistance (ΔE=1.3).
[0043] Comparative Example 3: After the surfactant and inhibitor were replaced, the interfacial compatibility decreased and the overall performance was significantly reduced.
[0044] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.
Claims
1. A UV ink composition with good adhesion, characterized in that: The components include the following in percentage by mass: Prepolymer system: mixture of polyurethane acrylate and epoxy acrylate 38% to 52%; Monomer system: Acrylate monomer, including: 0.5% to 2.0% of methacrylated dopamine containing a catechol group, 3.0% to 8.0% of adamantyl-modified acrylate monomer, 12% to 20% of isobornyl acrylate, and 12% to 20% of tripropylene glycol diacrylate; Photoinitiator: mixed initiator, including: 2.0% to 4.5% 2,4,6-trimethylbenzoylphenylphosphine oxide, 1.5% to 3.5% 2-methyl-1-(4-methylthiophenyl)-2-morpholinyl-1-propanone; Functional additives: additives, including: microencapsulated metal salt 0.1% to 0.5%, fluorinated surfactant 0.3% to 1.0%, nano-silica 1.0% to 3.0%, and polymerization inhibitor 0.1% to 0.3%; Optional pigments: 5% organic or inorganic pigments.
2. The UV ink composition according to claim 1, wherein: In the prepolymer system, the mass ratio of polyurethane acrylate to epoxy acrylate is 2:
1.
3. The UV ink composition according to claim 1, wherein: The adamantyl modified acrylate monomer is adamantane methacrylate or adamantane ethyl acrylate; The microencapsulated metal salt is one of iron acetylacetonate or copper acetylacetonate, and has a particle size of 30-80 nm; The fluorine-containing surfactant is one of perfluoropolyether acrylate or fluorocarbon-modified silicone; The polymerization inhibitor is one of p-methoxyphenol or hydroquinone; The nano-silica is hydrophobic fumed silica and has a specific surface area of 150-250 m² / g.
4. A method for preparing the UV ink according to any one of claims 1 to 3, characterized in that: The steps include: Step 101, pre-dispersion: microencapsulated metal salt, nano silicon dioxide and Mix with high-quality tripropylene glycol diacrylate and grind to a fineness of ≤5μm; Step 102: Mix the main ingredients: Add polyurethane acrylate, epoxy acrylate, Isobornyl acrylate, remaining Tripropylene glycol diacrylate, methacrylated dopamine containing a catechol group, and adamantyl-modified acrylate monomers were placed in a 40°C constant temperature water bath with a frame-type stirring blade (500 rpm, 30 minutes) and vacuum degassing (-0.08 MPa, 10 minutes) to remove dissolved air; Step 103, adding auxiliary agents: adding fluorinated surfactant and polymerization inhibitor, and dispersing in a high-speed disperser (1200 rpm, 15 minutes) until the system has no visible particles, and performing a secondary vacuum degassing (-0.09 MPa, 20 minutes) and storing in a dark place; Step 104: Adding photoinitiator: dissolve 2,4,6-trimethylbenzoylphenylphosphine oxide and 2-methyl-1-(4-methylthiophenyl)-2-morpholinyl-1-propanone in the remaining Add the main material system to isobornyl acrylate, stir at 300 rpm for 15 minutes, filter through a 400-mesh stainless steel filter, and adjust the viscosity to 300-600 mPa·s; Step 105, dispersion grinding: adding pigment, mechanically stirring at a rotation speed of 2500 rpm for 40 minutes, and then grinding to a scraper fineness of ≤10 μm to obtain the UV ink.
5. The method for preparing a UV ink with good adhesion according to claim 4, characterized in that: When the microencapsulated metal salt is ferric acetylacetonate, the preparation method of the metallized microcapsules is as follows: Ferric acetylacetonate was dissolved in anhydrous ethanol, and hexadecyltrimethylammonium bromide was added. The mixture was ultrasonically treated (40 kHz, 30 minutes) to form a uniform dispersion. Ethyl orthosilicate and ammonia water were slowly added under stirring (500 rpm). The mixture was reacted at 50°C for 6 hours. The ethyl orthosilicate was hydrolyzed and condensed to form a SiO2 coating layer. The coating thickness was controlled by adjusting the amount of ethyl orthosilicate (target: 30-50 nm). The reaction solution was centrifuged (8000 rpm, 10 minutes) and washed three times with anhydrous ethanol to remove unreacted products. The mixture was then vacuum dried at 60°C for 12 hours to obtain brown powder microcapsules.
6. The method for preparing a UV ink with good adhesion according to claim 5, characterized in that: The mass ratio of the ethyl orthosilicate to ferric acetylacetonate is 4:1, and the concentration of the used hexadecyltrimethylammonium bromide is 0.5% (w / v).
7. A method for curing UV ink according to any one of claims 1 to 3, characterized in that: Here are the steps: Step 201: reacting β-cyclodextrin with isocyanatepropyltriethoxysilane in a polar solvent to generate a cyclodextrin-silane coupling agent, mixing the coupling agent with ethanol and an acidic catalyst, ultrasonically dispersing the mixture, and then aging the mixture to obtain a substrate pretreatment solution; Step 202: spray the pretreatment liquid onto the substrate, bake at 100°C for 5 minutes, apply the ink onto the pretreated substrate, and cure it sequentially using a dual-wavelength UV light source of 365nm and 395nm, with curing energies of 200-300mJ / cm² and 800-1200mJ / cm², respectively. Step 203: Circulate hot air at 60°C for 2 minutes to complete curing.
8. The UV ink curing method according to claim 7, characterized in that: The specific preparation method of the substrate pretreatment liquid is: Mix 20% β-cyclodextrin, 9% isocyanatepropyltriethoxysilane, and 71% N,N-dimethylformamide in a mass ratio, and stir at 80°C under nitrogen with magnetic stirring (300 rpm) for 12 hours. Pour the reaction solution into icy ether for precipitation, vacuum filter, and dry at 60°C for 24 hours to obtain a white powder, which is the β-cyclodextrin modified silane coupling agent. The obtained β-cyclodextrin modified silane coupling agent (0.8%), acetic acid (0.5%), and anhydrous ethanol (98.7%) were mixed, and then dispersed by 40 kHz ultrasonic treatment for 30 minutes (power density 0.5 W / cm³). The mixture was allowed to stand at 25° C. in the dark for 24 hours to form a transparent sol to obtain the substrate pretreatment solution.