A UV-curable inkjet metallic coating agent for industrial printhead printing and its preparation method

Abstract

This invention provides a UV-curable inkjet metallic coating agent for industrial printhead printing and its preparation. It provides excellent adhesion to the printing medium and excellent interlayer adhesion with the printing ink in industrial printhead inkjet digital printing using UV inks. The curable coating agent of this application comprises pure acrylic resin, polyester resin, amine-modified co-initiator, acrylate monomers, photoinitiator, phosphate ester adhesion promoter, silane adhesion promoter, leveling agent, defoamer, and stabilizer. The weight ratio of different additives meets the requirements for media adhesion, and the weight ratio of different acrylate monomers and stabilizers solves the problems of ink flow and stability. Because this coating agent is applied simultaneously with the ink during the printing process, efficiency is improved, and the defect of residual coating agent when manually wiping the coating during printing cutout images is eliminated.

Description

Technical Field

[0001] This invention relates to a UV-curable inkjet metallic coating agent for industrial printhead printing and its preparation, belonging to the field of fine chemical technology. Background Technology

[0002] UV inkjet digital printing technology uses non-contact inkjet printing and assembly line production. Many products that can be produced on an assembly line or processed on an assembly line can be printed using UV inkjet digital printing, and it allows for personalization and small-batch customization. As UV inkjet printers expand into various fields, they are gradually changing traditional printing methods. However, due to differences in their application processes, their adhesion to the substrate is generally not as good as traditional printing methods. While UV inkjet printers can print on various materials, differences in the flexibility and other properties of different materials, as well as the adhesion of UV inks, can cause peeling or flaking on some materials. This necessitates the use of UV coatings to address these issues. Currently, the mainstream UV coating is a wipe coating, which involves spraying or manually wiping the substrate to improve ink adhesion. The disadvantages are an additional step, and the possibility of missed or uneven wiping affecting yield; furthermore, some coatings, due to their strong corrosiveness, can directly leave wiping marks or alter the gloss on the material surface. Printed cutout images may show color differences between the printed and uncoated areas, especially on non-planar printing materials, where the impact is greater.

[0003] Therefore, it is necessary to develop a coating that can be printed using a printhead, which reduces the number of steps and solves the problem of color difference in wiped coatings. Currently, the main type of machine-printed coating developed is the UV-cured coating agent. Water-based coating agents require energy to evaporate water and have poor wettability with the substrate, while solvent-based coating agents are not considered as a research direction due to their environmental impact. Summary of the Invention

[0004] Technical issues

[0005] Based on the above background, the present invention provides a UV-curable inkjet coating agent, which has good adhesion to metal materials such as iron, and the printing smoothness and stability of the coating agent are also very good, without clogging or slanted printing.

[0006] Technical solution

[0007] To address the aforementioned problems, this invention provides a UV-curable inkjet coating agent, used as an adhesive in printing to improve the adhesion between the substrate and the ink. The coating agent comprises the following components by total weight:

[0008]

[0009]

[0010] In one embodiment of the present invention, the modified acrylate resin includes one or more of polyurethane acrylate, polyester acrylate, and pure acrylic resin.

[0011] Furthermore, the polyurethane acrylate includes one or more of Changxing 6112-100, Changxing 6123-100, Nippon Seiki 7605B, Nippon Seiki 3000B, and Wuxing W300.

[0012] Furthermore, the polyester acrylate includes one or more of Changxing 6361-100, Changxing 6333-100, Wuxing EA8133, Wuxing EA8135, Wuxing EM8202, and Digo LTH.

[0013] Furthermore, the pure acrylate includes one or more of Mitsubishi BR113, Deqian ADK, Japan Daisaku DAP-A, DSM B-805, Changxing A-870, Changxing 6071, Boxin B-73, and Degussa AP.

[0014] Preferably, the modified acrylate resin is DIGIC LTH or Degussa AP.

[0015] Specifically, the modified acrylate resin can be Degussa AP.

[0016] In one embodiment of the present invention, the acrylate monomers include monofunctional acrylate monomers and polyfunctional acrylate monomers.

[0017] In one embodiment of the present invention, the acrylate monomer contains one or more of the following: cyclic structure, hydroxyl group, ethoxy group, propoxy group, amino group, and amino group.

[0018] Furthermore, the acrylate monofunctional monomers include one or more of the following: trimethylolpropane methyl acetal acrylate (CTFA), 4-tert-butylcyclohexyl acrylate (TBCHA), 2-phenoxyethyl acrylate (PHEA), tetrahydrofurfuryl acrylate (THFA), 3,3,5-trimethylcyclohexyl acrylate (TMCHA), dicyclopentenyl acrylate (DCPA), o-phenylphenoxyethyl acrylate (OPPEA), ethoxyethoxyethyl acrylate (EOEOEA), ethoxyphenoxy acrylate (PH2EOA), and 2-hydroxyethyl acrylate (β-CEA).

[0019] Furthermore, the acrylate multifunctional monomers include one or more of the following: 1,6-hexanediol diacrylate (HDDA), tricyclodecanedimethylethanol diacrylate (DCPDA), dipropylene glycol diacrylate (DPGDA), tripropylene glycol diacrylate (TPGDA), polyethylene glycol diacrylate (PEGDA), 1,4-butanediol diacrylate (1,4-BDDA), 1,3-butanediol diacrylate (BGDA), neopentyl glycol diacrylate (NPGDA), propoxylated neopentyl glycol diacrylate (NPG2PODA), and ethoxylated trimethylolpropane triacrylate (TMP3EOTA).

[0020] Furthermore, acrylate monomers containing monofunctional amino structures include one or more of acrylamide morpholine (ACMO), dimethylacrylamide (DMAA), and N-vinylcarbazole (NVC).

[0021] Preferably, the acrylate monomers include 2-hydroxyethyl acrylate (β-CEA), dimethacrylamide (DMAA), 3,3,5-trimethylcyclohexyl acrylate (TMCHA), 4-tert-butylcyclohexyl acrylate (TBCHA), tetrahydrofurfuryl acrylate (THFA), 2-phenoxyethyl acrylate (PHEA), trimethylolpropane methyl acetal acrylate (CTFA), and 1,6-hexanediol diacrylate (HDDA).

[0022] Specifically, the acrylate monomers that can be selected are dimethacrylamide (DMAA), 3,3,5-trimethylcyclohexyl acrylate (TMCHA), 4-tert-butylcyclohexyl acrylate (TBCHA), tetrahydrofurfuryl acrylate (THFA), and 2-phenoxyethyl acrylate (PHEA).

[0023] In one embodiment of the present invention, the photoinitiator includes one or more of acylphosphine oxide photoinitiators, α-hydroxy ketone photoinitiators, α-amino ketone photoinitiators, thioxanthone photoinitiators, and other co-initiators.

[0024] Furthermore, the photoinitiator is at least one of 1-hydroxycyclohexylphenyl ketone (184), 2-hydroxy-2-methyl-1-phenylpropanone (1173), 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO), 2-isopropylthioxanthone (ITX), methyl o-benzoylbenzoate (OMBB), ethyl 4-dimethylaminobenzoate (EDB), 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone (907), Sartoma CN371, Jiuri 1846, Jiuwei 8000, and BASF 94F.

[0025] Preferably, the photoinitiator includes at least one of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO), 2-hydroxy-2-methyl-1-phenylpropanone (1173), 1-hydroxycyclohexylphenyl ketone (184), and 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone (907).

[0026] Specifically, the photoinitiators can be 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO) and 2-hydroxy-2-methyl-1-phenylacetone (1173).

[0027] In one embodiment of the present invention, the adhesion promoter includes phosphate ester adhesion promoters and titanate ester adhesion promoters.

[0028] Furthermore, phosphate ester adhesion promoters include PM-2, PM1520EC, PM2010SP, PM3060, Changxing EM39, Lubrizol 2063, Lubrizol 2062, and Lubrizol 33507.

[0029] Furthermore, titanate adhesion promoters include ZJ-316, bis(dioctyloxypyrophosphate) ethylene titanate KR-238S, and other additives include one or more of LTW and ADK.

[0030] Preferably, adhesion promoters include PM-2, PM1520EC, Lubrizol 2063, and ZJ-316.

[0031] Specifically, the adhesion promoters that can be selected are PM1520EC and ZJ-316.

[0032] In one embodiment of the present invention, the siloxane additive includes one or more of the following materials: Dow Corning OFS-6040, OFS-6030, OFS-6341, OFS-6403, OFS-6020, KH-550, KH-560, KH-570, KH-304, and ZCA-N39.

[0033] In one embodiment of the present invention, the leveling agent includes one or more of EFKA3050, EFKA3030, EFKA3035, EFKA3600, EFKA3755, EFKA3777AN, EFKA3883, EFKA3258, TEGO370, TEGO410, TEGO432, TEGO450, BYK377, BYK333, BYK3500, BYK3600, BYK358N, BYK306, and BYK3510.

[0034] Preferably, the leveling agent is BYK3510.

[0035] In one embodiment of the present invention, the stabilizer includes at least one of phenols, quinones, aromatic amines, and aromatic nitrobenzene aluminum compounds.

[0036] Furthermore, the stabilizers include one or more of the following: Lyon G16, Lyon G22, p-hydroxyanisole, BASF UV22, BASF UV25, tris(N-nitroso-N-phenylhydroxylamine) aluminum salt, and hydroquinone.

[0037] Preferably, the leveling agent is Rayon G22.

[0038] This invention provides a method for preparing the above-mentioned UV-curable inkjet metallic coating agent, comprising the following steps:

[0039] (1) Mix the modified acrylic resin and acrylate monomer A to form component 1;

[0040] (2) Mix component 1 and acrylate monomer B to obtain component 2;

[0041] (3) Mix component 2 and photoinitiator to obtain component 3;

[0042] (4) Mix component 3 with adhesion promoter, leveling agent and stabilizer to obtain component 4;

[0043] (5) Filter component 4 to obtain UV-curable inkjet metal coating agent.

[0044] Furthermore, in step (1), the mass ratio of modified acrylic resin to acrylate monomer A is 8 to 12:1.

[0045] Furthermore, in step (1), the modified acrylic resin is either Tigo LTH or Degussa AP.

[0046] Furthermore, in step (1), the acrylate monomer A is 2-hydroxyethyl acrylate (β-CEA) or dimethylacrylamide (DMAA).

[0047] Furthermore, in step (2), the acrylate monomer B includes 2-hydroxyethyl acrylate (β-CEA), dimethacrylamide (DMAA), 3,3,5-trimethylcyclohexyl acrylate (TMCHA), 4-tert-butylcyclohexyl acrylate (TBCHA), tetrahydrofurfuryl acrylate (THFA), 2-phenoxyethyl acrylate (PHEA), trimethylolpropane methyl acetal acrylate (CTFA), and 1,6-hexanediol diacrylate (HDDA).

[0048] Furthermore, in step (3), the photoinitiator includes at least one of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO), 2-hydroxy-2-methyl-1-phenylpropanone (1173), 1-hydroxycyclohexylphenyl ketone (184), and 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone (907).

[0049] Furthermore, the adhesion promoters in step (4) include PM-2, PM1520EC, Lubrizol 2063 and ZJ-316.

[0050] Furthermore, the leveling agent in step (4) includes one or more of the following: EFKA3050, EFKA3030, EFKA3035, EFKA3600, EFKA3755, EFKA3777AN, EFKA3883, EFKA3258, TEGO370, TEGO410, TEGO432, TEGO450, BYK377, BYK333, BYK3500, BYK3600, BYK358N, BYK306, and BYK3510.

[0051] Furthermore, the stabilizer in step (4) includes one or more of the following: Lyon G16, Lyon G22, p-hydroxyanisole, BASF UV22, BASF UV25, tris(N-nitroso-N-phenylhydroxylamine) aluminum salt, and hydroquinone.

[0052] The present invention relates to the application of the UV-curable inkjet metallic coating agent described above in the field of inkjet printing.

[0053] Beneficial effects

[0054] The UV-curable inkjet coating agent provided by this invention allows for solvent-free printing, with 100% solid residue remaining on the substrate. Under UV curing lamp irradiation, the coating agent cures rapidly and dries instantly, allowing for immediate stacking and subsequent processing. It contains no volatile solvents, i.e., a 100% solvent-free formula, thus preventing the release of volatile organic compounds into the air during printing, meeting environmental regulations, and eliminating solvent recovery costs. This coating agent exhibits excellent adhesion to the substrate, quickly levels after printing, and helps conceal material defects and unevenness. Furthermore, the coating agent provides excellent printing smoothness and stability, preventing nozzle clogging and misaligned printing. Attached Figure Description

[0055] Figure 1 This is a graph of the adhesion test using the cross-cut adhesion test method in Example 1.

[0056] Figure 2 This is a graph of the adhesion test using the cross-cut adhesion test method in Example 2.

[0057] Figure 3This is a graph of the adhesion test using the cross-cut adhesion test method in Example 3.

[0058] Figure 4 This is a graph of the adhesion test using the cross-cut adhesion test method in Example 4.

[0059] Figure 5 This is a graph of the adhesion test using the cross-cut adhesion test method in Example 5.

[0060] Figure 6 This is a graph of the adhesion test using the cross-cut adhesion test method in Example 6.

[0061] Figure 7 This is a graph of the adhesion test using the cross-cut adhesion test method in Example 7.

[0062] Figure 8 This is a graph showing the adhesion test results of the cross-cut adhesion test in Comparative Example 1.

[0063] Figure 9 This is a graph showing the adhesion test results of the cross-cut adhesion test in Comparative Example 2.

[0064] Figure 10 This is a graph showing the adhesion test results of the cross-cut adhesion test in Comparative Example 3.

[0065] Figure 11 This is a graph showing the adhesion test results of the cross-cut adhesion test in Comparative Example 4.

[0066] Figure 12 This is a graph showing the adhesion test results of the cross-cut adhesion test in Comparative Example 5. Specific implementation part

[0067] Example 1

[0068] (1) Take LTH and β-CEA in a mass ratio of 10:1 and stir them in a mixer at 2000 rpm to form a homogeneous liquid to make a mixture (component A);

[0069] (2) Add the A component prepared in step (1) and DMAA, TMCHA, TBCHA, ACMO, THFA, β-CEA and PHEA according to the proportions in Table 1, and stir with a mixer at 1000 rpm to form a uniform liquid B.

[0070] (3) Add TPO and 1173 to the homogeneous liquid B after stirring in step (2), and then stir until completely dissolved to form homogeneous liquid C;

[0071] (4) Add PM-2, ZJ316, Byk3510 and G22 to the homogeneous liquid C after stirring in step (3) according to the proportions in Table 1, and then stir evenly to obtain the finished product.

[0072] (5) Filter the finished product obtained in step (4) to obtain UV-curable inkjet metal coating agent.

[0073] The specific steps of Examples 2-7 and Comparative Examples 1-4 are the same as those of Example 1. Among them, component B is prepared by mixing LTH and DMAA in a mass ratio of 10:1, and the specific method is the same as step (1) of Example 1; component C is prepared by mixing AP and β-CEA in a mass ratio of 10:1, and the specific method is the same as step (1) of Example 1; component D is prepared by mixing AP and DMAA in a mass ratio of 10:1, and the specific method is the same as step (1) of Example 1.

[0074] Table 1. Components and proportions of Examples 1-7 and Comparative Examples 1-4

[0075]

[0076]

[0077] Table 2 Specific Test Results

[0078]

[0079] Note 1. Adhesion test evaluation criteria using the cross-cut adhesion test:

[0080] ISO Grade 0, ASTM Grade 5B: The cut edges are completely smooth, and there is no peeling at the grid edges.

[0081] ISO Grade 1, ASTM Grade 4B: Small pieces peel off at the intersection of the cuts, and the actual damage within the gridded area does not exceed 5%.

[0082] ISO Grade 2, ASTM Grade 3B: Peeling is present at the cut edges and intersections, covering an area of ​​5%-15%.

[0083] ISO Grade 3, ASTM Grade 2B: Peeling at the cut edges, large areas of peeling off, or even partial peeling of individual grids, with a peeled area of ​​15%-35%.

[0084] ISO Grade 4, ASTM Grade 1B: Large areas of the cut edge are peeling off, some grids are completely peeled off, and the peeled area is 35%-65%.

[0085] ISO Class 5, ASTM Class 0B: Above the previous class.

[0086] 2. Comparison 5 is an external wipeable coating. Because its viscosity surface cannot pass through the print head, only its performance is compared.

[0087] 3. Pencil Hardness Test Method: Use a Mitsubishi 6B-6H pencil from Japan. Sharpen the pencil with a pencil sharpener to a 4-6 mm cylindrical lead (do not loosen or damage the lead). Hold the pencil perpendicular to 400# sandpaper and grind it on the sandpaper until a smooth, sharp edge is obtained (the edge should not be broken or chipped). After one use, rotate the pencil 180° or resharpen it before use. Fix the sample on a horizontal surface. Hold the sharpened pencil at a 45-degree angle to the coating and push it forward at a speed of one millimeter per second. The force should be enough to break the pencil edge or plow through the coating. Start with the hardest pencil, and repeat 5 times for each level. If the pencil plows through the coating twice out of 5 times, switch to a softer pencil. Continue until you find a pencil that cannot plow through the coating at least 4 times out of 5 times. The hardness of this pencil is the pencil hardness of the tested coating.

[0088] 4. The test metal is iron material used for printer factory testing.

[0089] 5. Viscosity was measured using a Brookfield Wells cone-plate viscometer.

[0090] 6. Surface tension test was performed using JZ200A from Chengde Precision Testing Machine Co., Ltd.

[0091] 7. The smoothness test was conducted using a Dingli 2513 printer with a Ricoh G6 printhead. Printing a 2m*1m varnish block, a printout with fewer than 3 broken needles was considered a pass; otherwise, it was a fail.

[0092] Table 3. Specific test results of ink stability

[0093]

[0094] Note: For the filtration test, a 1.0μm pore size glass fiber membrane from Kebotai and a 0.45μm pore size PP filter are used. A filtration time difference of less than 5% before and after aging is considered passing; otherwise, it fails. For the aging stability test, the membrane is aged at 60℃ for one week, and the viscosity is tested. A viscosity change of less than 10% is considered passing; otherwise, it fails. After aging, a flowability test with fewer than 5 pin breaks in the printed circuit is considered passing; otherwise, it fails.

[0095] According to the comparative test in Table 1, Example 3 passed the cross-cut adhesion test. The viscosity was lower than that of the external wipeable coating. This is because the printer industry uses monomers with low viscosity, low shrinkage, and good wetting properties. The viscosity is controlled below 20 cps, and all of them are photocurable monomers.

[0096] The dimethacrylamide used in Example 3, containing -NH2, is an acrylamide-based UV monomer suitable for photocuring reactions. It has strong thinning and viscosity-reducing abilities and excellent compatibility with various UV resins. DMAA has a micro-etching, swelling, and bonding effect on polyolefins, unsaturated polyesters, ABS, PC, PMMA, untreated PET, and even PP and PE, as well as various plastic films, thus better promoting adhesion. Its reaction efficiency is higher than that of ordinary monomers, and it has strong thinning ability and good adhesion.

[0097] Acryloylmorpholine used is a vinyl monomer suitable for photocuring reactions and free radical curing systems. It is a monofunctional monomer with low odor, low viscosity, good hardness and flexibility, and a relatively fast curing speed. In coating agents, it acts as a dispersant, adhesive, and facilitates rapid absorption and drying during high-curing-speed processes.

[0098] The N-vinylcarbazole used exhibits excellent adhesion and a good balance of hardness and toughness, demonstrating outstanding adhesion on a variety of metal substrates. It also exhibits strong dilution properties, with a viscosity of 2.88 mPa·s at 50 degrees Celsius, demonstrating excellent dilution performance.

[0099] The cyclotrimethylolpropane methyl acetal acrylate used exhibits high flexibility, excellent adhesion (to plastics and metals), good abrasion resistance and chemical resistance, and strong dilution effect; low shrinkage; excellent adhesion (to plastics and metals), and possesses certain drying and waterproof properties. The TMCHA used has good adhesion, low shrinkage, low viscosity, and low surface tension, and plays a role in increasing wetting with the substrate in the coating agent.

[0100] Based on the fact that all of the above monomers are environmentally friendly, have little environmental pollution, and are biodegradable.

[0101] The PM1520EC used is 2-hydroxyethyl methacrylate phosphate, with an acid value of 280-300. Its drying properties and adhesion are superior to other phosphate esters.

[0102] The primary external coating is a traditional solvent-based wipe coating, whose viscosity and surface area are greater than those of the printable coating, making it unsuitable for printhead printing. The external wipe coating contains thinner, including volatile and environmentally unfriendly solvents such as methyl isobutyl ketone, cyclohexanone, butyl acetate, isopropanol, and ethyl acetate, which pollute the environment and have a strong odor. Example 3, however, has no VOC emissions, low odor, and is environmentally friendly.

[0103] In summary, the performance and stability of Example 3 meet the requirements of industrial head printing. Its adhesion is superior to that of external wipeable coatings, and its advantages are even more obvious when printing cutout images and some non-planar printing materials.

[0104] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.

Claims

1. A UV-curable inkjet coating agent, characterized in that, The coating agent, by weight, consists of the following components: Component B (15 parts), 3,3,5-trimethylcyclohexyl acrylate (TMCHA) (15 parts), 4-tert-butylcyclohexyl acrylate (TBCHA) (5 parts), tetrahydrofurfuryl acrylate (THFA) (15 parts), 2-hydroxyethyl acrylate (β-CEA) (15 parts), 2-phenoxyethyl acrylate (PHEA) (7.5 parts), acrylamide (ACMO) (3 parts), dimethacrylamide (DMAA) (14.4 parts), photoinitiator (TPO) (8 parts), photoinitiator 1173 (0.5 parts), phosphate ester adhesion promoter (PM1520EC) (1 part), titanate ester adhesion promoter (ZJ-316) (0.5 parts), leveling agent (Byk3510) (0.1 parts), stabilizer (G22) (0.5 parts); Component B is a mixture of polyester acrylate LTH and dimethacrylamide DMAA in a mass ratio of 10:

1.

2. The application of the UV-curable inkjet coating agent according to claim 1 in the field of inkjet printing.

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