Prime coating ink for metal surface as well as preparation method and application of prime coating ink

Abstract

The invention belongs to the technical field of ink, and particularly relates to prime coat ink for a metal surface as well as a preparation method and application of the prime coat ink. The prime coat ink for the metal surface, provided by the invention, is prepared from the following raw materials in percentage by mass: 5 to 10 percent of acid modified acrylate oligomer, 0.1 to 2 percent of silane coupling agent, 60 to 80 percent of reactive diluent, 5 to 20 percent of acrylate oligomer, 5 to 15 percent of photoinitiator and 0.5 to 2 percent of additive, the silane coupling agent has at least one of an acryloyloxy group and a derivative group thereof, and a methacryloyloxy group and a derivative group thereof. The primer ink provided by the invention can still have very high adhesive force under the condition that the metal surface is not pretreated. Colored UVLED jet ink is continuously sprayed on the prime coat ink film layer, so that the adhesion capability of subsequent UVLED jet ink on the metal surface can be greatly improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ink, and particularly relates to a primer ink for a metal surface and a preparation method and application thereof. BACKGROUND

[0002] The first color ordinary commemorative coin issued in China laid the application technology foundation of the color jet printing process on ordinary commemorative coins. In order to further enrich the artistic expression of future ordinary commemorative coins, it is necessary to reserve the color jet printing process of complex color jet printing effect patterns in advance, so as to prepare for the development of high-quality color ordinary commemorative coins with more delicate and colorful patterns.

[0003] In order to be able to continuously issue high-quality jet printing pattern ordinary commemorative coins with rich colors, delicate patterns and novel themes, and at the same time realize the goal of independent production of jet printing ink products, meet the needs of future color ordinary commemorative coin issuance, it is necessary to develop jet printing ink that can achieve stable and excellent adhesion on the surface of a coin, and the jet printing primer ink plays a very key role. The existing metal substrate surface jet printing technology still has some defects and limitations. The metal surface is smooth and dense, and needs to be pretreated before printing, such as plasma wind, etching, etc., which increases the time and labor cost. Direct jet printing on the metal surface, the adhesion of free radical type ink is poor, and it is easy to fall off or fade. SUMMARY

[0004] Therefore, the technical problem to be solved by the present application is to overcome the defects of the existing metal substrate surface jet printing technology, direct jet printing on the metal surface, and poor adhesion of free radical type ink, and to provide a primer ink for a metal surface and a preparation method and application thereof.

[0005] The present application provides a primer ink for the surface of a coin, and the raw materials of the primer ink include, in terms of mass percentage, 5-10% of acid-modified acrylate oligomer, 0.1-2% of silane coupling agent, 60-80% of active diluent, 5-20% of acrylate oligomer, 5-15% of photoinitiator and 0.5-2% of auxiliary agent.

[0006] The silane coupling agent has at least one of an acryloyloxy group and a derivative group thereof, and a methacryloyloxy group and a derivative group thereof.

[0007] Preferably, the structure general formula of the silane coupling agent is (YR) n SiX 4-n YR is selected from the structures of any one of the following groups:

[0008]

[0009] wherein, Ar1, Ar2 are each independently selected from substituted or unsubstituted C1-C6 alkylene;

[0010] Preferably, Ar1, Ar2 are each independently selected from substituted or unsubstituted C1-C3 alkylene;

[0011] Preferably, X is selected from at least one of halogen, alkoxy, acyloxy;

[0012] Preferably, X is selected from the group consisting of:

[0013] -OCH3, -OCH2CH3, -F, -Cl, -Br, -I, -OOCH3, -OOCH2CH3;

[0014] Preferably, X is selected from at least one of -OCH3, -OCH2CH3;

[0015] Optionally, the acid-modified acrylate resin oligomer comprises at least one of phosphoric acid-modified acrylate resin oligomer, sulfuric acid-modified acrylate resin oligomer and organic acid-modified acrylate resin oligomer.

[0016] In the present application, YR represents a non-hydrolyzable organic group, and X represents a group that can undergo a hydrolysis reaction and generate Si—OH.

[0017] The silane coupling agent of the specific general structure of the present application cooperates with the acid-modified acrylate oligomer firmly, and is significantly superior to other types of silane coupling agents, and has a stronger synergistic effect with the acid-modified acrylate oligomer. In the UV ink system, the silane coupling agent undergoes a hydrolysis reaction with trace amounts of moisture in the air or the ink, generates silanol, the substrate surface usually contains hydroxyl groups, the silanol and the hydroxyl groups on the substrate surface form stable siloxane bonds through condensation reaction, thereby connecting one end of the silane to the substrate surface, and the functional groups at the other end can chemically react with active groups such as double bonds in the organic components such as resins in the UV ink during the UV light-induced curing reaction, form covalent bonds, and realize the chemical bonding connection between the ink and the substrate. At the same time, it plays a bridging role, effectively fixes the ink components on the substrate, and improves the adhesion of the ink.

[0018] Preferably, the acid-modified acrylate oligomer is selected from at least one of CN147, SR9051NS, GENORAD 40, 9083, TO94F, KM2103, Photomer2203, Photomer 4703, AgiSyn 9771, EBECRYL171, EBECRYL168, P1-M, P2-M;

[0019] The silane coupling agent is selected from at least one of KH-570, LT-570, Z-6030, A174, methacryloxypropyl triethoxysilane, etc.

[0020] The acrylate oligomer is selected from at least one of EB870, EB810, EB81, EB1360, EB1029, CN293, CN2300, CN2301, CN2302, CN2303, CN2304, 6043;

[0021] The photoinitiator is selected from at least one of MBF, DEAP, 1173, 184, 907, 369, TEPO, TPO, 819, ITX, CTX, CPTX, DETX, EDAB.

[0022] Optionally, the photoinitiator is used alone or in combination to achieve curing under a UV LED ultraviolet light source of 365 nm, 385 nm, 395 nm.

[0023] Preferably, the acid-modified acrylate oligomer is selected from at least one of CN147, SR9051NS of Sartomer, GENORAD 40 of RAHN, 9083, TO94F of BASF, KM2103 of Jin Cheng Chemical, Photomer2203, Photomer4703 of IGM, AgiSyn 9771 of DSM, EBECRYL171, EBECRYL168 of Allnex, P1-M, P2-M of Nippon Shokubai;

[0024] The silane coupling agent is selected from at least one of KH-570 of Guangzhou Yuanda New Material, LT-570 of Hubei Xinlantian New Material, Z-6030 of Dow Corning, A174 of American Momentive, methacryloxypropyl triethoxysilane of Shanghai Pindet, etc.

[0025] The acrylate oligomer is selected from at least one of EB870, EB810, EB81, EB1360, EB1029 of Allnex, CN293, CN2300, CN2301, CN2302, CN2303, CN2304 of Sartomer, 6043 of Rayon.

[0026] The photoinitiator is selected from at least one of MBF, DEAP, 1173, 184, 907, 369 of BASF, TEPO, TPO, 819, ITX, CTX, CPTX, DETX, EDAB of IGM.

[0027] Preferably, the acid-modified acrylate oligomer is P1-M, EBECRYL 168 and GENORAD 40;

[0028] Optionally, the mass ratio of the P1-M, EBECRYL 168 and GENORAD 40 is (2-5):(0-5):(0-3);

[0029] Preferably, the mass ratio of the P1-M, EBECRYL 168 and GENORAD 40 is (2-5):(2-5):(0.1-3);

[0030] Optionally, the silane coupling agent is KH-570 and A174;

[0031] Optionally, the mass ratio of the KH-570 and A174 is (0-4):(0.1-2);

[0032] Optionally, the mass ratio of the KH-570 and A174 is (0.1-4):(0.1-2);

[0033] The acrylate oligomer is CN2302 and 6043;

[0034] Preferably, the mass ratio of the CN2302 and 6043 is (4-5):(1-3);

[0035] The photoinitiator is 819, TPO and ITX;

[0036] Preferably, the mass ratio of the 819, TPO and ITX is (0-2):(1-4):(1-4);

[0037] Preferably, the mass ratio of the 819, TPO and ITX is (0.1-2):(1-4):(1-4).

[0038] Preferably, the reactive diluent includes at least one of a monofunctional acrylate monomer, a difunctional acrylate monomer and a multifunctional acrylate monomer;

[0039] Preferably, the monofunctional acrylate monomer is at least one of benzyl acrylate (BZA), N,N-diethyl acrylamide (DEAA), N,N-dimethyl acrylamide (DMAA), acryloyl morpholine (ACMO), isobornyl acrylate (IOBA), trimethylolcyclohexyl acrylate (TMCHA), 4-tert-butyl cyclohexyl acrylate (TBCHA), tetrahydrofurfuryl acrylate (THFA), N-vinyl pyrrolidone (NVP), cyclotrimethylolpropane formal acrylate (CTFA), isodecyl alcohol acrylate (IDA), 2-phenoxyethyl acrylate (PHEA), 3-methyl-1,5-pentanediol diacrylate (MPDA);

[0040] Preferably, the difunctional acrylate monomer is at least one of 1,6-hexanediol diacrylate (HDDA), neopentyl glycol diacrylate (NPGDA), dipropylene glycol diacrylate (DPGDA), tripropylene glycol diacrylate (TPGDA).

[0041] Preferably, the multifunctional acrylate monomer is at least one of trimethylolpropane triacrylate (TMPTA), trimethylolpropane ethoxy triacrylate (TMP(EO)TA), trimethylolpropane propoxy triacrylate (TMP(PO)TA).

[0042] Preferably, the reactive diluent is trimethylolcyclohexyl acrylate (TMCHA), N,N-diethyl acrylamide (DEAA), tetrahydrofurfuryl acrylate (THFA), tripropylene glycol diacrylate (TPGDA), and trimethylolpropane ethoxy triacrylate (TMP(EO)TA).

[0043] Preferably, the mass ratio of the trimethylolcyclohexyl acrylate (TMCHA), N,N-diethyl acrylamide (DEAA), tetrahydrofurfuryl acrylate (THFA), tripropylene glycol diacrylate (TPGDA), and trimethylolpropane ethoxy triacrylate (TMP(EO)TA) is (2-4):(1-2):(0.5-4):(0.1-1):(0.1-1).

[0044] Preferably, the auxiliary agent includes a leveling agent and a polymerization inhibitor.

[0045] Preferably, the leveling agent is at least one of BYK-333, BYK-3500, BYK-3505, BYK-3760, EFKA FL3 199, WE3220, TEG02300, TEG02500, SW452.

[0046] Preferably, the polymerization inhibitor is selected from at least one of BHT, MEHQ, lrgastab UV-22, lrgastab UV-25, UV292;

[0047] Preferably, the leveling agent is BYK-333; the polymerization inhibitor is lrgastab UV-22.

[0048] Preferably, the mass ratio of the leveling agent and the polymerization inhibitor is (0.1-1):(0.1-1).

[0049] Preferably, the leveling agent is selected from at least one of BYK-333, BYK-3500, BYK-3505, BYK-3760 of BYK company, EFKA FL3 199, WE3220 of BASF company, TEG02300, TEG02500 of Wanhua company, and SW452 of Sinochem.

[0050] Preferably, the polymerization inhibitor is selected from at least one of BHT, MEHQ, lrgastab UV-22, lrgastab UV-25, UV292 of Merck company.

[0051] Preferably, the leveling agent is BYK-333; the polymerization inhibitor is lrgastab UV-22.

[0052] The application provides a preparation method of the primer ink for a metal surface.

[0053] The raw materials of the primer ink are stirred and mixed to obtain the primer ink.

[0054] Preferably, the preparation method of the primer ink for a metal surface comprises the following steps.

[0055] The active diluent is first stirred and mixed, then the acid-modified acrylate oligomer, the silane coupling agent and the acrylate oligomer are secondly stirred and mixed, and then the additives and the photoinitiator are thirdly stirred and mixed to obtain the primer ink.

[0056] Optionally, the first stirring and mixing speed is 800-1000 rpm, and the first stirring and mixing time is 0.5 h-1 h.

[0057] The second stirring and mixing speed is 800-1000 rpm, and the second stirring and mixing time is 0.5 h-1 h.

[0058] The third stirring and mixing process includes stirring and mixing at a speed of 200-400 rpm for 10-20 minutes, and then stirring and mixing at a speed of 1000-1500 rpm for 1-1.5 hours.

[0059] Optionally, the third stirring and mixing step may further include a filtering step after completion;

[0060] Optionally, the filter has a pore size of 0.2-2.0 μm.

[0061] This invention provides a UVLED free radical inkjet ink, which includes the base coating ink for metal surfaces described above or the base coating ink for metal surfaces prepared by the preparation method described above.

[0062] Preferably, the UVLED radical inkjet ink also includes colored UVLED inkjet ink.

[0063] This invention provides an application of the above-described primer ink for metal surfaces, or the primer ink for metal surfaces prepared by the above-described preparation method, or the above-described UVLED free radical inkjet ink in metal surface coating inks;

[0064] Optionally, the primer ink is coated onto the metal surface and then UV cured;

[0065] Optionally, the metal includes coins;

[0066] Optionally, when the base coating ink is UV cured on the metal surface to form a base coating ink film, the process may also include spraying colored UV LED inkjet onto the formed base coating ink film and performing a second UV curing treatment.

[0067] This invention does not specifically limit the coating method; typically, non-limiting methods include spraying.

[0068] Optionally, the UV LED light power used for UV curing is 8-16W / cm². 2 The UV LED lamp irradiation wavelength is 360-400nm;

[0069] Optionally, the UVLED lamp has an irradiation wavelength of 365nm, 385nm, or 395nm.

[0070] The technical solution of this invention has the following advantages:

[0071] 1. The primer ink for metal surface provided by the present application, the raw materials of the primer ink include, in percentage by mass, 5-10% of acid-modified acrylate oligomer, 0.1-2% of silane coupling agent, 60-80% of active diluent, 5-20% of acrylate oligomer, 5-15% of photoinitiator, and 0.5-2% of auxiliary agent; the silane coupling agent has at least one of acryloyloxy group and its derivative group and methacryloyloxy group and its derivative group. The acid-modified acrylate oligomer makes the formula primer ink have certain acidity, so that the formula primer ink can reduce the oxidation barrier layer of the metal surface when in contact with the metal surface, and the adhesion of the primer ink can be improved; the silane coupling agent with acryloyloxy group or methacryloyloxy group is a special organosilicon compound, which has organic functional groups and hydrolyzable groups in the molecular structure, wherein the acryloyloxy group or the methacryloyloxy group serves as the organic functional group, has strong reactivity with different matrix resins, and can cooperate with the acid-modified acrylate oligomer to improve the adhesion of the primer ink to the metal surface. The acid-modified acrylate oligomer and the special silane coupling agent are used in the present application to achieve synergistic cooperation, so that the primer ink can be rapidly cured under ultraviolet conditions, the adsorption between the primer ink and the metal surface is enhanced, and the primer ink still has high adhesion to the metal surface without pretreatment. The color UVLED inkjet can be continuously sprayed on the primer ink film layer, so that the adhesion of the subsequent UVLED inkjet ink to the metal surface can be greatly improved.

[0072] 2. The primer ink for metal surface provided by the present application can improve the resistance of the subsequent color layer, and the extremely low viscosity of the primer ink also makes the ink suitable for common inkjet heads on the market, such as Ricoh and Kodak, and also suitable for Samba inkjet heads suitable for fine printing.

[0073] 3. The primer ink for metal surface provided by the present application is very safe compared with non-UV type solvent-based ink; the volatile organic compound content VOC is less than or equal to 10%, which is much lower than that of solvent-based ink, and is very environmentally friendly; the primer ink provided by the present application does not need to be additionally diluted with a solvent, and has the advantages of low viscosity and good adhesion to metal substrates. DETAILED DESCRIPTION

[0074] The following examples are provided to better further understand the present application, and do not limit the content and protection scope of the present application, and do not constitute a limitation, anyone who is inspired by the present application or combines the present application with other prior art features to obtain any product same or similar to the present application, falls within the protection scope of the present application.

[0075] The specific experimental steps or conditions are not indicated in the examples, and the operation or conditions can be carried out according to the conventional experimental steps described in the literature in the art. The reagents or instruments used are not indicated by the manufacturer, and are conventional reagent products that can be obtained by purchase.

[0076] Example 1

[0077] The present embodiment provides a primer ink for a metal surface, and the specific components and contents are shown in Table 1.

[0078] The present embodiment provides a preparation method of a primer ink for a metal surface, which comprises the following steps:

[0079] First, the active diluent is stirred at a speed of 800 rpm for 0.5 h, then the acid-modified acrylate oligomer, the silane coupling agent and the acrylate oligomer are stirred at a speed of 800 rpm for 0.5 h, then the additives and the photoinitiator are stirred at a speed of 200 rpm for 10 min, and then stirred at a speed of 1500 rpm for 1 h, and then filtered using a filter device with a pore size of 2 μm. The primer ink is obtained after filtration.

[0080] Example 2

[0081] The present embodiment provides a primer ink for a metal surface, which is different from Example 1 only in the content of the specific components, and the details are shown in Table 1.

[0082] The present embodiment provides a preparation method of a primer ink for a metal surface, which is the same as Example 1.

[0083] Example 3

[0084] The present embodiment provides a primer ink for a metal surface, which is different from Example 1 only in the content of the specific components, and the details are shown in Table 1.

[0085] The present embodiment provides a preparation method of a primer ink for a metal surface, which is the same as Example 1.

[0086] Example 4

[0087] The present embodiment provides a primer ink for a metal surface, which is different from Example 1 only in the content of the specific components, and the details are shown in Table 1.

[0088] The present embodiment provides a preparation method of a primer ink for a metal surface, which is the same as Example 1.

[0089] Example 5

[0090] The embodiment provides a primer ink for a metal surface, which is only different from the embodiment 1 in contents of specific components, and details are shown in Table 1.

[0091] The embodiment provides a preparation method of the primer ink for the metal surface, which is the same as the embodiment 1.

[0092] Table 1

[0093]

[0094] Embodiment 6

[0095] The embodiment provides a primer ink for a metal surface, specific components and contents of which are shown in Table 2.

[0096] The embodiment provides a preparation method of the primer ink for the metal surface, which comprises the following steps.

[0097] The active diluent is first stirred and mixed at a speed of 900 rpm for 1 h, then the acid-modified acrylate oligomer, the silane coupling agent and the acrylate oligomer are stirred and mixed at a speed of 900 rpm for 1 h, the additives and the photoinitiator are first stirred and mixed at a speed of 300 rpm for 20 min, then stirred and mixed at a speed of 1300 rpm for 1.3 h, and finally filtered by using a filter device with a pore size of 1 μm, so that the primer ink is obtained.

[0098] Table 2

[0099]

[0100] Embodiment 7

[0101] The embodiment provides a primer ink for a metal surface, specific components and contents of which are shown in Table 3.

[0102] The embodiment provides a preparation method of the primer ink for the metal surface, which comprises the following steps.

[0103] The active diluent is first stirred and mixed at a speed of 1000 rpm for 0.7 h, then the acid-modified acrylate oligomer, the silane coupling agent and the acrylate oligomer are stirred and mixed at a speed of 1000 rpm for 0.7 h, the additives and the photoinitiator are first stirred and mixed at a speed of 400 rpm for 15 min, then stirred and mixed at a speed of 1000 rpm for 1.5 h, and finally filtered by using a filter device with a pore size of 2 μm, so that the primer ink is obtained.

[0104] Table 3

[0105]

[0106] Comparative Example 1

[0107] The comparative example provides a primer ink for a metal surface, which is different from example 1 only in that the silane coupling agent is vinyl tri(2-methoxyethoxy) silane (PC6130, Nanjing Xisibo Organic Silicon Co., Ltd.), as shown in Table 4.

[0108] The comparative example provides a primer ink for a metal surface, which is different from example 1 only in that the silane coupling agent is vinyl tri(2-methoxyethoxy) silane (PC6130, Nanjing Xisibo Organic Silicon Co., Ltd.), as shown in Table 4.

[0109] Table 4

[0110]

[0111] Comparative Example 2

[0112] The comparative example provides a primer ink for a metal surface, which is different from example 1 only in that the silane coupling agent is vinyl tri(2-methoxyethoxy) silane (PC6130, Nanjing Xisibo Organic Silicon Co., Ltd.), as shown in Table 4.

[0113] The comparative example provides a primer ink for a metal surface, which is different from example 1 only in that the silane coupling agent is vinyl tri(2-methoxyethoxy) silane (PC6130, Nanjing Xisibo Organic Silicon Co., Ltd.), as shown in Table 4.

[0114] Table 5

[0115]

[0116]

[0117] Test Example

[0118] The viscosity and surface tension of the primer inks of examples 1-7 and comparative examples 1-2 were tested, the test standard of viscosity was GB / T 13217.4-2020, and the test standard of surface tension was GB / T 42415-2023.

[0119] The primer inks of examples 1-7 and comparative examples 1-2 were respectively sprayed on the surface of a coin made of smooth brass alloy material using Samba GL, the printing speed was 20 m / min, and after spraying, the film was directly cured using a 16W / cm 2 395nm wavelength UVLED curing lamp, after curing, the film was complete and no uncured ink remained on the finger, which was the end of curing, the curing time was recorded, and the adhesion grade of the primer ink after curing was tested, the test standard of adhesion grade was GB / T 9286-2021. Then the color UVLED inkjet (Sunjet JFUNC3575 of Sunchemical) was continuously sprayed on the formed primer ink film, and a 16W / cm 2The curing process is performed using a 395 nm wavelength UV LED lamp, and after curing, the film layer is complete and there is no ink residue on the finger, which is the end of curing. At the same time, a control experiment is set up, in which no primer ink is used, and the color UV LED ink (Sunjet JFUNC3575 of Sun chemical company) is directly sprayed on the surface of the coin made of brass alloy with smooth surface, and a 16W / cm 2 The curing process is performed using a 395 nm wavelength UV LED lamp, and after curing, the film layer is complete and there is no ink residue on the finger, which is the end of curing. The color ink is used to print on the metal coin; after the color UV LED ink curing is completed, the adhesion grade is tested, and the adhesion grade test standard is GB / T 9286-2021, the adhesion grade is divided into 0-5 levels, among which 0 level: no peeling; 1 level: peeling not more than 5%; 2 level: peeling 5%-15%; 3 level: peeling 15%-35%; 4 level: peeling 35%-65%; 5 level: peeling more than 65%. The test results are shown in Table 6.

[0120] Table 6

[0121]

[0122] The specific primer ink of the present application has good printing fluency, and after printing, it is directly cured using a 16W / cm2 395nm wavelength UV-LED curing lamp, and after curing, it has good adhesion on the coin, with an adhesion grade of 0, and no peeling at all. Continue to use other color inks for coverage, and after curing, the entire film layer also has good adhesion, with an adhesion grade of 0. Using Comparative Example 1, the primer without adding silane coupling agent, the adhesion of the subsequent colored film layer is 3; using Comparative Example 2, the primer without adding acid-modified value, the adhesion of the subsequent colored film layer is 4; at the same time, the control experiment is set up without using primer ink, and the color ink is directly used to print on the metal coin, with an adhesion grade of 5.

[0123] Obviously, the above examples are only examples for clarity, and not a limitation on the embodiments. Based on the above description, other different forms of changes or variations can be made by those of ordinary skill in the art. Here, it is not necessary and impossible to exhaust all embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A primer ink for metal surfaces, characterized in that, The raw materials of the primer ink, by weight percentage, include: 5-10% acid-modified acrylate oligomer, 0.1-2% silane coupling agent, 60-80% reactive diluent, 5-20% acrylate oligomer, 5-15% photoinitiator, and 0.5-2% additives. The silane coupling agent has at least one of an acryloyloxy group and its derivatives, or a methacryloyloxy group and its derivatives.

2. The primer ink for metal surfaces according to claim 1, characterized in that, The general structural formula of the silane coupling agent is (YR). n SiX 4-n YR is selected from any of the following structures: Ar1 and Ar2 are each independently selected from substituted or unsubstituted C1-C6 alkylene groups; Preferably, Ar1 and Ar2 are each independently selected from substituted or unsubstituted C1-C3 alkylene groups; X is selected from at least one of halogen, alkoxy, and acyloxy; Preferably, X is a group selected from the group consisting of: -OCH3, -OCH2CH3, -F, -Cl, -Br, -I, -OOCH3, -OOCH2CH3; Preferably, X is selected from at least one of -OCH3 and -OCH2CH3; Optionally, the acid-modified acrylate resin oligomer includes at least one of phosphoric acid-modified acrylate resin oligomer, sulfuric acid-modified acrylate resin oligomer, and organic acid-modified acrylate resin oligomer.

3. The primer ink for metal surfaces according to claim 1, characterized in that, The acid-modified acrylate oligomer is selected from at least one of CN147, SR9051NS, GENORAD 40, 9083, TO94F, KM2103, Photomer2203, Photomer4703, AgiSyn 9771, EBECRYL171, EBECRYL168, P1-M, and P2-M. The silane coupling agent is selected from at least one of KH-570, LT-570, Z-6030, A174, and methacryloxypropyltriethoxysilane; The acrylate oligomer is selected from at least one of EB870, EB810, EB81, EB1360, EB1029, CN293, CN2300, CN2301, CN2302, CN2303, CN2304, and 6043; The photoinitiator is selected from at least one of MBF, DEAP, 1173, 184, 907, 369, TEPO, TPO, 819, ITX, CTX, CPTX, DETX, and EDAB.

4. The primer ink for metal surfaces according to any one of claims 1-3, characterized in that, The acid-modified acrylate oligomers are P1-M, EBECRYL168, and GENORAD40; Optionally, the mass ratio of P1-M, EBECRYL168 and GENORAD40 is (2-5):(0-5):(0-3); Preferably, the mass ratio of P1-M, EBECRYL168, and GENORAD40 is (2-5):(2-5):(0.1-3); Optionally, the silane coupling agent is KH-570 and A174; Optionally, the mass ratio of KH-570 to A174 is (0-4):(0.1-2); Optionally, the mass ratio of KH-570 to A174 is (0.1-4):(0.1-2); The acrylate oligomers mentioned are CN2302 and 6043; Preferably, the mass ratio of CN2302 to 6043 is (4-5):(1-3); The photoinitiator is 819, TPO, and ITX; Preferably, the mass ratio of 819, TPO and ITX is (0-2):(1-4):(1-4); Preferably, the mass ratio of 819, TPO and ITX is (0.1-2):(1-4):(1-4).

5. The primer ink for metal surfaces according to any one of claims 1-4, characterized in that, The reactive diluent includes at least one of monofunctional acrylate monomers, difunctional acrylate monomers, and polyfunctional acrylate monomers. Preferably, the monofunctional acrylate monomer is at least one selected from benzyl acrylate, N,N-diethylacrylamide, N,N-dimethylacrylamide, acrylmorpholine, isobornyl acrylate, trimethylolcyclohexyl acrylate, 4-tert-butylhexyl acrylate, tetrahydrofurfuryl acrylate, N-vinylpyrrolidone, cyclotrimethylolpropane formal acrylate, isodecanol acrylate, 2-phenoxyethyl acrylate, and 3-methyl-1,5-pentanediol diacrylate. Preferably, the difunctional acrylate monomer is selected from at least one of 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, dipropylene glycol diacrylate, and tripropylene glycol diacrylate. Preferably, the multifunctional acrylate monomer is selected from at least one of trimethylolpropane triacrylate, trimethylolpropane ethoxytriacrylate, and trimethylolpropane propoxytriacrylate; Preferably, the reactive diluent is trimethylolcyclohexyl acrylate, N,N-diethylacrylamide, tetrahydrofurfuryl acrylate, tripropylene glycol diacrylate, and trimethylolpropane ethoxytriacrylate. Preferably, the mass ratio of trimethylolcyclohexyl acrylate, N,N-diethylacrylamide, tetrahydrofurfuryl acrylate, tripropylene glycol diacrylate and trimethylolpropane ethoxytriacrylate is (2-4):(1-2):(0.5-4):(0.1-1):(0.1-1).

6. The primer ink for metal surfaces according to any one of claims 1-5, characterized in that, The additives include leveling agents and polymerization inhibitors; Preferably, the leveling agent is selected from at least one of BYK-333, BYK-3500, BYK-3505, BYK-3760, EFKA FL3 199, WE3220, TEG02300, TEG02500, and SW452; Preferably, the polymerization inhibitor is selected from at least one of BHT, MEHQ, lrgastab UV-22, lrgastab UV-25, and UV292; Preferably, the leveling agent is BYK-333; the polymerization inhibitor is lrgastab UV-22; Preferably, the mass ratio of the leveling agent to the polymerization inhibitor is (0.1-1):(0.1-1).

7. A method for preparing a primer ink for a metal surface as described in any one of claims 1-6, characterized in that, Includes the following steps: The raw materials for the base coating ink are stirred and mixed to obtain the base coating ink.

8. The method for preparing a primer ink for metal surfaces according to claim 7, characterized in that, Includes the following steps: First, the reactive diluent is stirred and mixed for the first time. Then, acid-modified acrylate oligomer, silane coupling agent and acrylate oligomer are added and stirred and mixed for the second time. Then, the additives and photoinitiator are added and stirred and mixed for the third time to obtain the base coating ink. Optionally, the first stirring speed is 800-1000 rpm, and the first stirring time is 0.5h-1h; The second stirring speed is 800-1000 rpm, and the second stirring time is 0.5h-1h; The third stirring and mixing process includes stirring and mixing at a speed of 200-400 rpm for 10-20 minutes, and then stirring and mixing at a speed of 1000-1500 rpm for 1-1.5 hours.

9. A UVLED free radical inkjet ink, characterized in that, The UVLED free radical inkjet ink includes the base coating ink for metal surfaces as described in any one of claims 1-6 or the base coating ink for metal surfaces prepared by the preparation method described in claim 7 or 8. Preferably, the UVLED radical inkjet ink also includes colored UVLED inkjet ink.

10. The application of the primer ink for metal surfaces according to any one of claims 1-6, or the primer ink for metal surfaces prepared by the preparation method according to claim 7 or 8, or the UVLED free radical inkjet ink according to claim 9 in metal surface coating inks; Optionally, the primer ink is coated onto the metal surface and then UV cured; Optionally, the metal includes coins; Optionally, when the base coating ink is UV cured on the metal surface to form a base coating ink film, the process may also include spraying colored UV LED inkjet onto the formed base coating ink film and performing a second UV curing treatment.

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