UV tin printing ink

Abstract

The invention relates to the technical field of printing ink, in particular to UV (ultraviolet) tin printing ink, which is prepared from the following raw materials in parts by weight: 40 to 50 parts of maleic anhydride grafted epoxy acrylate; 10 to 15 parts of polyurethane acrylate; 4-6 parts of a photoinitiator; 25 to 30 parts of a reactive diluent; 8-12 parts of a surface modification filler; 5-8 parts of titanium dioxide; 0.1 to 0.3 part of a deodorant; and 0.5-1 part of an auxiliary agent. According to the UV tin printing ink provided by the invention, the maleic anhydride grafted epoxy acrylate is introduced, and carboxyl of maleic anhydride (MAH) in the maleic anhydride grafted epoxy acrylate and hydroxyl on the metal surface form a hydrogen bond or a coordinate bond, so that the UV tin printing ink is endowed with a polarity anchoring effect, and the interface bonding force is enhanced.

Description

Technical Field

[0001] This invention relates to the field of printing ink technology, and more particularly to a UV printing ink for metal. Background Technology

[0002] UV (ultraviolet) curable inks, as an environmentally friendly and efficient new ink system, have been increasingly widely used in the field of tinplate printing. Due to their advantages such as fast curing speed, low energy consumption, and no solvent evaporation, UV tinplate inks have gradually replaced traditional thermosetting inks and become the mainstream in metal packaging printing.

[0003] However, due to the high surface energy and weak interfacial bonding of metals, existing UV printing inks have insufficient adhesion to metal substrates, which limits their application. Summary of the Invention

[0004] To address the problem of poor adhesion of existing UV tinplate printing inks to metal substrates, this invention provides a UV tinplate printing ink that enhances interfacial bonding with the metal substrate by introducing maleic anhydride-grafted epoxy acrylate and other components, thus solving the problem of poor adhesion of existing UV tinplate printing inks to metal substrates.

[0005] The technical solution adopted by this invention to solve its technical problem is: A UV printing ink for metal, by weight, comprises the following components: 40-50 parts of maleic anhydride-grafted epoxy acrylate; 10-15 parts of polyurethane acrylate; 4-6 parts of photoinitiator; 25-30 parts of reactive diluent; 8-12 parts of surface-modifying filler; 5-8 parts titanium dioxide; Odor remover 0.1-0.3 parts; Additives: 0.5-1 part.

[0006] Optionally, the maleic anhydride-grafted epoxy acrylate is prepared by introducing maleic anhydride into the matrix through free radical grafting using bisphenol A epoxy resin.

[0007] Optionally, the maleic anhydride-grafted epoxy acrylate is prepared according to the following method: S1: The bisphenol A epoxy resin, the maleic anhydride, and the initiator are dissolved in methyl methacrylate and stirred under an inert atmosphere at 80-90°C to obtain a reaction mixture; S2: The reaction mixture is subjected to vacuum distillation to obtain maleic anhydride-grafted epoxy acrylate.

[0008] Optionally, the mass ratio of the bisphenol A epoxy resin, the maleic anhydride, the initiator, and the methyl methacrylate is 100:(15-20):(0.5-1):(50-80).

[0009] Optionally, the surface-modified filler is silane coupling agent modified nano-calcium carbonate.

[0010] Optionally, the silane coupling agent modified nano-calcium carbonate is prepared by the following method: nano-calcium carbonate is dispersed in a solvent, silane coupling agent and acetic acid are added, the mixture is stirred and reacted at 60°C, the product is centrifuged and washed until neutral, vacuum dried and then ground to obtain silane coupling agent modified nano-calcium carbonate.

[0011] Optionally, the mass ratio of the nano-calcium carbonate to the silane coupling agent is 100:(3-5).

[0012] Optionally, the polyurethane acrylate is an aliphatic polyurethane acrylate.

[0013] Optionally, the reactive diluent is isobornyl acrylate.

[0014] Optionally, the additive is selected from at least one of leveling agents and defoamers.

[0015] The beneficial effects of this invention are: The UV printing ink provided by this invention introduces maleic anhydride-grafted epoxy acrylate, and utilizes the carboxyl groups of maleic anhydride (MAH) in the maleic anhydride-grafted epoxy acrylate to form hydrogen bonds or coordination bonds with the hydroxyl groups on the metal surface, thereby giving the UV printing ink a polar anchoring effect and enhancing the interfacial adhesion. Detailed Implementation

[0016] The present invention will now be described in further detail. The embodiments described below are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0017] To address the problem of poor adhesion of existing UV tinplate printing inks to metal substrates, this invention provides a UV tinplate printing ink, the raw materials of which, by weight, comprise the following components: 40-50 parts of maleic anhydride-grafted epoxy acrylate; 10-15 parts of polyurethane acrylate; 4-6 parts of photoinitiator; 25-30 parts of reactive diluent; 8-12 parts of surface-modifying filler; 5-8 parts titanium dioxide; Odor remover 0.1-0.3 parts; Additives: 0.5-1 part.

[0018] The UV printing ink provided by this invention introduces maleic anhydride-grafted epoxy acrylate, and utilizes the carboxyl groups of maleic anhydride (MAH) in the maleic anhydride-grafted epoxy acrylate to form hydrogen bonds or coordination bonds with the hydroxyl groups on the metal surface, thereby giving the UV printing ink a polar anchoring effect and enhancing the interfacial adhesion.

[0019] The present invention preferably uses maleic anhydride-grafted epoxy acrylate as a bisphenol A epoxy resin matrix and introduces maleic anhydride through free radical grafting to prepare a resin with both polar anchoring effect and flexible segments by introducing maleic anhydride groups through free radical grafting using bisphenol A epoxy resin as a matrix.

[0020] Specifically, maleic anhydride-grafted epoxy acrylate is prepared according to the following method: S1: Bisphenol A epoxy resin, maleic anhydride, and initiator are dissolved in methyl methacrylate (MMA), and the mixture is stirred and reacted under an inert atmosphere at 80-90°C for 3-4 hours to obtain the reaction mixture. S2: The reaction mixture is subjected to vacuum distillation to remove unreacted MMA, yielding maleic anhydride-grafted epoxy acrylate.

[0021] The maleic anhydride-grafted epoxy acrylate prepared by this method has the advantage that the carboxyl groups of maleic anhydride can form hydrogen bonds or coordination bonds with the hydroxyl groups on the metal surface, thereby enhancing the interfacial bonding force. The epoxy skeleton provides rigid support, and the acrylate end groups ensure photopolymerization activity. The three work together to construct a strong "metal-resin" interfacial bonding system. At the same time, the flexible MMA segments reduce the crosslinking density and improve impact resistance.

[0022] Furthermore, the present invention preferably uses BPO as the initiator, and preferably uses a mass ratio of bisphenol A epoxy resin, maleic anhydride, initiator and methyl methacrylate of 100:(15-20):(0.5-1):(50-80).

[0023] Existing UV printing inks rely on the high refractive index of titanium dioxide for white inks. However, traditional titanium dioxide is prone to agglomeration, has poor compatibility with resins, and poor hiding power. Dark inks require multiple printing cycles, resulting in low efficiency. Therefore, this invention preferably uses silane coupling agent modified nano-calcium carbonate as the surface-modifying filler. This silane coupling agent modified nano-calcium carbonate uses nano-calcium carbonate (preferably with a particle size range of 40-60 nm) as raw material and modifies its surface with a silane coupling agent to improve its compatibility and dispersibility with resins, reduce agglomeration, and increase hiding power.

[0024] Specifically, the present invention preferably prepares silane coupling agent modified nano-calcium carbonate according to the following method: nano-calcium carbonate is dispersed in a solvent, silane coupling agent and acetic acid are added, the pH is adjusted to 4-5 by acetic acid, the reaction is stirred at 60°C, the product is centrifuged and washed until neutral, vacuum dried and ground to obtain silane coupling agent modified nano-calcium carbonate.

[0025] The specific process is as follows: Disperse nano-calcium carbonate in anhydrous ethanol / water mixed solution and sonicate for 30 min; add KH-570 and acetic acid (to adjust pH=4-5), stir and react at 60℃ for 2 h; centrifuge and wash until neutral, vacuum dry and grind to obtain silane coupling agent modified nano-calcium carbonate.

[0026] The preferred solvent of this invention is a mixed solution of anhydrous ethanol and water in a volume ratio of 9:1; the preferred silane coupling agent is γ-methacryloxypropyltrimethoxysilane (KH-570); during the preparation of nano-calcium carbonate modified by silane coupling agent, the methoxy group of KH-570 hydrolyzes and condenses with the hydroxyl group on the surface of CaCO3. The long carbon chain (-CH=CH2) participates in the UV curing reaction, which improves the bonding force between the filler and the resin, while reducing agglomeration and improving the hiding power; in addition, the double bond on the surface of the filler participates in the construction of the photopolymerization network, eliminates the interface defects between traditional fillers and resins, and significantly improves the elongation at break and impact resistance of the composite film.

[0027] Furthermore, the present invention preferably uses a mass ratio of nano-calcium carbonate to silane coupling agent of 100:(3-5).

[0028] The preferred polyurethane acrylate of this invention is an aliphatic polyurethane acrylate, whose flexible segments endow the film with excellent flexibility, while the rigid end groups provide crosslinking points. The balance between the two allows the cured film to take into account both hardness and elongation at break, which can effectively alleviate the interfacial stress caused by thermal expansion and contraction.

[0029] Conventional reactive diluents (such as TPGDA and HDDA) and some resins contain small amounts of unreacted monomers or low-molecular-weight byproducts, resulting in a noticeable pungent odor after curing, which fails to meet food-grade packaging requirements. Therefore, this invention preferably uses low-viscosity, low-volatility monofunctional monomers as reactive diluents to reduce unreacted monomer residues. Specifically, this invention preferably uses isobornyl acrylate (IBOA) as the reactive diluent. Its rigid bridged ring structure reduces volume shrinkage, its high boiling point and low volatility ensure leveling during coating, and it exhibits excellent compatibility with maleic anhydride-grafted epoxy acrylates and aliphatic polyurethane acrylates, promoting uniform densification of the three-dimensional network.

[0030] The preferred photoinitiator of this invention is a compound composed of photoinitiator 1173 and photoinitiator 184 in a mass ratio of 1:1, so as to achieve both surface drying and deep curing.

[0031] The titanium dioxide used in this invention is preferably rutile titanium dioxide, which provides high hiding power and UV shielding function, and inhibits interface degradation caused by UV aging.

[0032] The preferred odor remover of this invention is a food-grade odor remover (such as a plant extract coated with cyclodextrin) that adsorbs residual odor molecules.

[0033] The preferred additives in this invention are selected from at least one of leveling agents and defoamers, depending on the specific requirements.

[0034] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below.

[0035] Unless otherwise specified, in the embodiments and comparative examples of the present invention, the bisphenol A epoxy resin is Jiangsu Sanmu E51, the polyurethane acrylate is Guangzhou Songda SD877, the deodorizer is Foshan Dihui Chemical Co., Ltd. DH-C6003, the leveling agent is BYK358N, and the defoamer is BYK141.

[0036] The photoinitiators in the raw materials of UV tinplate printing ink are all a compound composed of photoinitiator 1173 and photoinitiator 184 in a mass ratio of 1:1.

[0037] Unless otherwise specified, the UV printing inks in the embodiments and comparative examples of this invention are prepared according to the following method: According to the formula, maleic anhydride-grafted epoxy acrylate, polyurethane acrylate, and reactive diluent are mixed and stirred for 10 minutes. Then, photoinitiator and deodorizer are added, and stirring is continued for 15 minutes. Surface-modifying filler, titanium dioxide, and additives are then slowly added and dispersed at high speed (2000 rpm) until uniform. The mixture is then ground to a fineness of ≤5μm using a three-roll mill, filtered, and packaged to obtain UV printing ink.

[0038] Example 1 This embodiment provides a UV printing ink for metal printing. The raw materials of this UV printing ink, by weight, include the following components: 45 parts of maleic anhydride-grafted epoxy acrylate; 12 parts polyurethane acrylate; 5 parts of photoinitiator; IBOA 28 copies; 10 parts of nano-calcium carbonate modified with silane coupling agent; TiO2 (rutile type) 7 parts; Odor remover 0.2 parts; 0.4 parts leveling agent; 0.4 parts of defoamer.

[0039] In this embodiment, maleic anhydride-grafted epoxy acrylate was prepared according to the following method: S1: Dissolve 100g of bisphenol A epoxy resin, 18g of maleic anhydride, and 0.8g of initiator BPO in 65g of methyl methacrylate (MMA), purge with nitrogen for protection, and stir at 85°C for 3.5h to obtain the reaction mixture. S2: The reaction mixture is subjected to vacuum distillation to remove unreacted MMA, yielding maleic anhydride-grafted epoxy acrylate.

[0040] In this embodiment, the silane coupling agent-modified nano-calcium carbonate was prepared according to the following method: 100g of nano-calcium carbonate was dispersed in 200mL of a mixed solution of anhydrous ethanol and water in a volume ratio of 9:1, and ultrasonically treated for 30min. 4g of KH-570 was added, and acetic acid was added to adjust the pH to 4-5. The mixture was stirred at 60℃ for 2h. After centrifugation and washing until neutral, the mixture was vacuum dried and ground to obtain silane coupling agent modified nano-calcium carbonate.

[0041] Example 2 This embodiment provides a UV printing ink for metal printing. The raw materials of this UV printing ink, by weight, include the following components: 40 parts of maleic anhydride-grafted epoxy acrylate; 15 parts polyurethane acrylate; 4 parts of photoinitiator; IBOA 25 copies; 8 parts of nano-calcium carbonate modified with silane coupling agent; TiO2 (rutile type) 5 parts; Odor remover 0.2 parts; 0.4 parts leveling agent; 0.4 parts of defoamer.

[0042] In this embodiment, the preparation methods of maleic anhydride-grafted epoxy acrylate and silane coupling agent-modified nano-calcium carbonate are the same as those in Example 1.

[0043] Example 3 This embodiment provides a UV printing ink for metal printing. The raw materials of this UV printing ink, by weight, include the following components: 50 parts of maleic anhydride-grafted epoxy acrylate; 10 parts polyurethane acrylate; 6 parts of photoinitiator; IBOA 30 copies; 12 parts of nano-calcium carbonate modified with silane coupling agent; TiO2 (rutile type) 8 parts; Odor remover 0.2 parts; 0.4 parts leveling agent; 0.4 parts of defoamer.

[0044] In this embodiment, the preparation methods of maleic anhydride-grafted epoxy acrylate and silane coupling agent-modified nano-calcium carbonate are the same as those in Example 1.

[0045] Example 4 The difference between this embodiment and Example 1 is that the maleic anhydride-grafted epoxy acrylate is prepared according to the following method: S1: Dissolve 100g of bisphenol A epoxy resin, 15g of maleic anhydride, and 0.5g of initiator BPO in 50g of methyl methacrylate (MMA), purge with nitrogen, and stir at 80°C for 4h to obtain the reaction mixture. S2: The reaction mixture is subjected to vacuum distillation to remove unreacted MMA, yielding maleic anhydride-grafted epoxy acrylate.

[0046] Example 5 The difference between this embodiment and Example 1 is that the maleic anhydride-grafted epoxy acrylate is prepared according to the following method: S1: Dissolve 100g of bisphenol A epoxy resin, 20g of maleic anhydride, and 1g of initiator BPO in 80g of methyl methacrylate (MMA), purge with nitrogen for protection, and stir at 90°C for 3h to obtain the reaction mixture. S2: The reaction mixture is subjected to vacuum distillation to remove unreacted MMA, yielding maleic anhydride-grafted epoxy acrylate.

[0047] Example 6 The difference between this embodiment and Example 1 is that the silane coupling agent modified nano-calcium carbonate is prepared according to the following method: 100g of nano-calcium carbonate was dispersed in 200mL of a mixed solution of anhydrous ethanol and water in a volume ratio of 9:1 and ultrasonically treated for 30min. 3g of KH-570 was added, and acetic acid was added to adjust the pH to 4-5. The mixture was stirred at 60℃ for 2h. After centrifugation and washing until neutral, the mixture was vacuum dried and ground to obtain silane coupling agent modified nano-calcium carbonate.

[0048] Example 7 The difference between this embodiment and Example 1 is that the silane coupling agent modified nano-calcium carbonate is prepared according to the following method: 100g of nano-calcium carbonate was dispersed in 200mL of a mixed solution of anhydrous ethanol and water in a volume ratio of 9:1, and ultrasonically treated for 30min. 5g of KH-570 was added, and acetic acid was added to adjust the pH to 4-5. The mixture was stirred at 60℃ for 2h. After centrifugation and washing until neutral, the mixture was vacuum dried and ground to obtain silane coupling agent modified nano-calcium carbonate.

[0049] Each comparative example in this invention is compared with Example 1.

[0050] Comparative Example 1 This comparative example provides a UV printing ink for metal printing, the raw materials of which, by weight, include the following components: 45 parts of bisphenol A epoxy resin; 12 parts polyurethane acrylate; 5 parts of photoinitiator; IBOA 28 copies; 10 parts of nano-calcium carbonate modified with silane coupling agent; TiO2 (rutile type) 7 parts; Odor remover 0.2 parts; 0.4 parts leveling agent; 0.4 parts of defoamer.

[0051] The preparation method of silane coupling agent modified nano-calcium carbonate in this comparative example is the same as that in Example 1.

[0052] Comparative Example 2 This comparative example provides a UV printing ink for metal printing, the raw materials of which, by weight, include the following components: 57 parts of polyurethane acrylate; 5 parts of photoinitiator; IBOA 28 copies; 10 parts of nano-calcium carbonate modified with silane coupling agent; TiO2 (rutile type) 7 parts; Odor remover 0.2 parts; 0.4 parts leveling agent; 0.4 parts of defoamer.

[0053] The preparation method of silane coupling agent modified nano-calcium carbonate in this comparative example is the same as that in Example 1.

[0054] Comparative Example 3 This comparative example provides a UV printing ink for metal printing, the raw materials of which, by weight, include the following components: 57 parts of maleic anhydride-grafted epoxy acrylate; 5 parts of photoinitiator; IBOA 28 copies; 10 parts of nano-calcium carbonate modified with silane coupling agent; TiO2 (rutile type) 7 parts; Odor remover 0.2 parts; 0.4 parts leveling agent; 0.4 parts of defoamer.

[0055] In this comparative example, the preparation methods of maleic anhydride-grafted epoxy acrylate and silane coupling agent-modified nano-calcium carbonate are the same as those in Example 1.

[0056] Comparative Example 4 This comparative example provides a UV printing ink for metal printing, the raw materials of which, by weight, include the following components: 45 parts of maleic anhydride-grafted epoxy acrylate; 12 parts polyurethane acrylate; 5 parts of photoinitiator; TPGDA 28 copies; 10 parts of nano-calcium carbonate modified with silane coupling agent; TiO2 (rutile type) 7 parts; Odor remover 0.2 parts; 0.4 parts leveling agent; 0.4 parts of defoamer.

[0057] In this comparative example, the preparation methods of maleic anhydride-grafted epoxy acrylate and silane coupling agent-modified nano-calcium carbonate are the same as those in Example 1.

[0058] Comparative Example 5 This comparative example provides a UV printing ink for metal printing, the raw materials of which, by weight, include the following components: 45 parts of maleic anhydride-grafted epoxy acrylate; 12 parts polyurethane acrylate; 5 parts of photoinitiator; IBOA 28 copies; TiO2 (rutile type) 7 parts; Odor remover 0.2 parts; 0.4 parts leveling agent; 0.4 parts of defoamer.

[0059] The performance of the UV printing inks prepared in the above embodiments and comparative examples was tested using the following methods: Adhesion test (cross-cut test): Reference standard: GB / T 9286-1998 "Paints and varnishes cross-cut test".

[0060] step: 1. The UV printing inks of each embodiment and comparative example were coated onto a degreased and polished tinplate (150mm×70mm×0.2mm in size), and the wet film thickness was controlled at 20±2 μm.

[0061] 2. UV curing conditions: Energy 800 mJ / cm 2(Mercury lamp, main wavelength 365 nm), conveying speed 10 m / min.

[0062] 3. After curing, leave it for 24 h, use a cross cutter to cut out 100 squares of 1 mm×1 mm, with the depth reaching the metal substrate.

[0063] 4. Paste 3M 610 tape on the square area, quickly peel it off at a 60° angle, and observe the peeling situation.

[0064] 5. Rating standard: Grade 0 (no peeling) to Grade 5 (≥65% peeling), Grade 0 is the best.

[0065] Impact resistance test (falling weight impact tester): Instrument: QC-712 falling weight impact testing machine (impact head diameter 12.7 mm, mass 500 g).

[0066] Steps: 1. Prepare and cure the specimen in the same way as the adhesion test.

[0067] 2. Place the specimen on the support table with the coating surface facing up.

[0068] 3. Let the impact head fall freely from a height of 50 cm, and observe whether the coating cracks or peels off.

[0069] 4. Judgment: No crack / peeling is recorded as qualified; cracks or peeling occur are recorded as unqualified. The maximum impact height can be recorded as a reference value.

[0070] Odor level test: Refer to the odor evaluation method in GB / T 18883-2002 "Indoor Air Quality Standard". Five trained perfume assessors smell the cured film in a closed state under the environment of 23±2℃ and 50±5% RH, and rate it according to 5 levels: Level 1 (no odor) - Level 5 (strongly irritating odor). Take the average value. For food contact use, it is required to be ≤2 levels.

[0071] Hiding power test: Refer to GB / T 1726-1979 "Determination Method of Hiding Power of Coatings (Black and White Grid Method)".

[0072] Steps: Coat a wet film with a thickness of 20±2 μm on the black and white grid card, and observe the minimum number of coating layers required for complete hiding after UV curing. The fewer the layers, the better the hiding power. The reflectance method can also be used: measure the L* difference between the black and white backgrounds with a color difference meter, and ΔL≥40 is excellent.

[0073] The test results are shown in Table 1: Table 1 The difference between Comparative Example 1 and Example 1 is that bisphenol A epoxy resin was used instead of maleic anhydride-grafted epoxy acrylate. Due to the lack of polar anchoring effect of maleic anhydride carboxyl groups forming hydrogen bonds or coordination bonds with hydroxyl groups on the metal surface, the interfacial bonding force decreased, the adhesion dropped to level 3, and the impact resistance failed.

[0074] The difference between Comparative Example 2 and Example 1 is that polyurethane acrylate was used instead of maleic anhydride-grafted epoxy acrylate. Although polyurethane acrylate is flexible, it does not have polar anchoring groups and cannot form a strong interaction with the metal surface, resulting in an adhesion level of only 4 and failure to meet the impact resistance requirements.

[0075] The difference between Comparative Example 3 and Example 1 is that maleic anhydride-grafted epoxy acrylate was used instead of polyurethane acrylate. Due to the lack of flexible chain segments of polyurethane acrylate to buffer thermal expansion and contraction stress, the impact resistance was not up to standard. Although the adhesion was improved (level 2), the brittleness of the film layer increased.

[0076] The difference between Comparative Example 4 and Example 1 is that TPGDA was used as the reactive diluent. Because TPGDA is a polyfunctional monomer, it has a large volume shrinkage during curing and a strong residual monomer odor, which causes the odor level to rise to 3.5, which does not meet the low odor requirements for food packaging.

[0077] The difference between Comparative Example 5 and Example 1 is that no silane coupling agent was added to modify the nano-calcium carbonate. Due to the poor compatibility between the filler and the resin and the tendency to agglomerate, the hiding power decreased and the interface defects increased, resulting in a hiding power ΔL of only 32 and an adhesion level of 1.

[0078] As can be seen from the above test data: Maleic anhydride-grafted epoxy acrylate significantly improves adhesion (grade 0) and impact resistance through the polar anchoring effect of carboxyl groups on the hydroxyl groups of metal surfaces. Silane coupling agent modified nano-calcium carbonate improves filler dispersibility and interfacial bonding, and enhances hiding power and film mechanical properties; IBOA combines low odor and low shrinkage properties, ensuring that the odor level of the cured film meets food contact requirements. The components work synergistically within the given ratio range of the invention to achieve comprehensive optimization of adhesion, impact resistance, hiding power and low odor, which is significantly better than the comparative example.

[0079] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A UV printing ink for metal, characterized in that, The raw materials comprise the following components by weight: 40-50 parts of maleic anhydride-grafted epoxy acrylate; 10-15 parts of polyurethane acrylate; 4-6 parts of photoinitiator; 25-30 parts of reactive diluent; 8-12 parts of surface-modifying filler; 5-8 parts titanium dioxide; Odor remover 0.1-0.3 parts; Additives: 0.5-1 part.

2. The UV printing ink for metal as described in claim 1, characterized in that, The maleic anhydride-grafted epoxy acrylate is prepared by introducing maleic anhydride into the matrix through free radical grafting using bisphenol A epoxy resin.

3. The UV printing ink for metal as described in claim 2, characterized in that, The maleic anhydride-grafted epoxy acrylate is prepared according to the following method: S1: The bisphenol A epoxy resin, the maleic anhydride, and the initiator are dissolved in methyl methacrylate and stirred under an inert atmosphere at 80-90°C to obtain a reaction mixture; S2: The reaction mixture is subjected to vacuum distillation to obtain maleic anhydride-grafted epoxy acrylate.

4. The UV printing ink for metal as described in claim 3, characterized in that, The mass ratio of the bisphenol A epoxy resin, the maleic anhydride, the initiator, and the methyl methacrylate is 100:(15-20):(0.5-1):(50-80).

5. The UV printing ink for iron as described in claim 1, characterized in that, The surface-modified filler is silane coupling agent modified nano-calcium carbonate.

6. The UV printing ink for metal as described in claim 5, characterized in that, The silane coupling agent modified nano-calcium carbonate was prepared by the following method: nano-calcium carbonate was dispersed in a solvent, silane coupling agent and acetic acid were added, the mixture was stirred and reacted at 60°C, the product was centrifuged and washed until neutral, vacuum dried and then ground to obtain silane coupling agent modified nano-calcium carbonate.

7. The UV printing ink for metal as described in claim 6, characterized in that, The mass ratio of the nano-calcium carbonate to the silane coupling agent is 100:(3-5).

8. The UV printing ink for metal as described in any one of claims 1-7, characterized in that, The polyurethane acrylate is an aliphatic polyurethane acrylate.

9. The UV printing ink for metal as described in any one of claims 1-7, characterized in that, The active diluent is isobornyl acrylate.

10. The UV printing ink for metal as described in any one of claims 1-7, characterized in that, The additive is selected from at least one of leveling agents and defoamers.

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