Uv white ink, its preparation method and application process

Abstract

The application provides a UV white ink, a preparation method and an application process. The preparation raw material of the UV white ink includes, in terms of weight parts, 5-10 parts of resin, 30-40 parts of amide functional monomer, 25-40 parts of active diluent, 5-10 parts of photoinitiator, 10-25 parts of titanium-containing white paste, and 0.3-3 parts of additive. The resin provides a film-forming skeleton, guarantees the adhesion and scratch resistance of the ink layer; the amide functional monomer uses strong polar amide groups to build low-shrinkage crosslinking nodes, balances the hardness and internal stress, and improves the alcohol resistance; the active diluent adjusts the viscosity of the system and participates in photocuring, and gives the ink good standby anti-settling property. Through the synergistic effect of the components, the application realizes high hardness and excellent scratch resistance, and takes into account the strong adhesion, alcohol resistance and long-term storage stability of the substrate, and is especially suitable for the inkjet printing process of cylindrical curved surfaces such as vacuum cups.

Description

Technical Field

[0001] This invention belongs to the field of new materials technology for UV-curable inkjet inks, specifically relating to a UV white ink, its preparation method and application process. Background Technology

[0002] Insulated water bottles, as everyday items, are made from materials including stainless steel, plastic, glass, and ceramic, with stainless steel dominating the market due to its excellent heat retention and durability. Currently, the mainstream pre-treatment methods for stainless steel insulated water bottles are electrostatic powder coating and two-component solvent-based baking paint, which impart rich colors and textures. In terms of decorative techniques, traditional screen printing and heat transfer printing technologies suffer from low pattern precision, inability to achieve curved surface gradients, and personalized customization. In contrast, UV inkjet printing (white ink base + CMYK color ink overprint + varnish topcoat) has become the mainstream direction for high-end decoration of insulated water bottles due to its advantages such as high-definition detail, good adaptability to curved surfaces, and the ability to achieve embossed effects.

[0003] However, commercially available general-purpose UV white inkjet inks suffer from severe adhesion problems when directly applied to substrates of thermos cups (especially dense stainless steel substrates) that have undergone powder coating or painting. They often fail cross-cut tests and peel off after thermal shock due to a lack of adhesion mechanisms specifically designed for dense coatings. Furthermore, general-purpose formulations exhibit poor chemical resistance (such as alcohol wiping, dishwasher cleaning, and salt spray resistance) and weather resistance, easily yellowing and fading. Excessive shrinkage during rapid curing can also lead to ink layer cracking or uneven ink buildup. In addition, titanium dioxide tends to agglomerate and settle in the system, causing reduced hiding power and printhead clogging, and the ink's rheological properties are difficult to adapt to the low-energy LED-UV rapid curing requirements of industrial-grade printheads (such as the Ricoh G5i). In summary, existing ordinary UV white inkjet inks lack the support of a dedicated resin system and the compounding of functional monomers, making it difficult to simultaneously meet the requirements of high adhesion, machine washability, and excellent printability on powder-coated and painted substrates. Therefore, there is an urgent need to develop a UV white inkjet ink and its supporting process suitable for curved surface decoration. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this application provides a UV white ink, its preparation method, and application process. The UV white ink of this application comprises resin, amide functional monomers, and reactive diluents, etc., which, through the matching of polarity and crosslinking kinetics, construct a dense crosslinked network possessing both high interfacial bonding strength and high bulk toughness. The resin provides the film-forming framework, ensuring the adhesion and scratch resistance of the ink layer; the amide functional monomers, through the construction of low-shrinkage crosslinking nodes using strongly polar amide groups, balance hardness and internal stress, improving the alcohol resistance of the white ink as a base layer; the reactive diluent adjusts the viscosity of the system and participates in photocuring crosslinking, giving the UV white ink good standby anti-settling properties. Combined with the synergistic effects of photoinitiators, titanium dioxide-containing pastes, and additives, this formulation achieves high hardness and excellent scratch resistance while also considering strong adhesion to the substrate, alcohol resistance, and long-term storage stability, making it particularly suitable for inkjet printing on cylindrical curved surfaces such as thermos cups.

[0005] To achieve the above objectives, in a first aspect, this application provides a UV white ink, wherein the raw materials for preparation, by weight, include: 5-10 parts resin; 30-40 parts of amide functional monomers; 25-40 parts of reactive diluent; 5-10 parts of photoinitiator; Contains 10-25 parts of titanium dioxide powder; Additives: 0.3-3 parts.

[0006] Optionally, the resin includes at least one of aldehyde-ketone resin, polyester resin, and pure acrylic resin.

[0007] Optionally, the glass transition temperature of the aldehyde-ketone resin is 45-70°C; and / or The glass transition temperature of the polyester resin is 40-80℃; and / or The weight-average molecular weight of the pure acrylic resin is 30,000-120,000 g / mol.

[0008] Optionally, the mass ratio of the resin to the amide functional monomer is 0.14-0.35; and / or The mass ratio of the amide functional monomer to the reactive diluent is 1-1.3.

[0009] Optionally, the amide functional monomers include acrylamide monofunctional monomers and N-vinyl lactam monofunctional monomers.

[0010] Optionally, the reactive diluent includes at least one of alicyclic (meth)acrylate reactive diluents and non-alicyclic (meth)acrylate reactive diluents.

[0011] Optionally, the photoinitiator comprises at least one of ethyl 2,4,6-trimethylbenzoylphenylphosphonate, (2,4,6-trimethylbenzoyl)di(p-tolyl)phosphine oxide, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide; and / or The titanium dioxide-containing slurry has a titanium dioxide solid content of 50-70% and an average particle size of 200-300 nm; and / or The additives include at least one of leveling agents and polymerization inhibitors.

[0012] Secondly, this application also provides a method for preparing a UV white ink as described in any one of the first aspects above, comprising the following steps: Mix 5-10 parts by weight of resin with 25-40 parts by weight of reactive diluent, add 30-40 parts by weight of amide functional monomer, 5-10 parts by weight of photoinitiator and 0.3-3 parts by weight of additives, stir, then add 10-25 parts by weight of titanium dioxide pigment paste, stir, filter, and obtain the UV white ink.

[0013] Furthermore, this application also provides an application process for UV white ink as described in any one of the first aspects above in cylindrical curved surface decoration printing, the application process comprising the following steps: The UV white ink is deposited onto the cylindrical curved surface using inkjet printing to form a wet white ink underlayer. The wet white ink underlay was cured using an LED-UV light source with a wavelength of 365 nm-405 nm to obtain a cured white ink underlay. The curing process uses an irradiation energy of 200-300 mJ / cm². 2 The dry film thickness of the white ink underlayer is 10-15 μm.

[0014] Optionally, the cylindrical curved surface is the surface of a powder-coated thermos cup and / or the surface of a painted thermos cup; When the cylindrical curved surface is the surface of a powder-coated insulated cup, the surface treatment steps of the powder-coated insulated cup include: Electrostatic spraying with polyester / epoxy powder was used to control the thickness of the powder coating layer to be 60-100 μm. The surface of the powder-coated thermos cup is baked and cured, and the baking temperature before printing is 160-180℃. When the cylindrical curved surface is the surface of a spray-painted thermos cup, the processing steps for the surface of the spray-painted thermos cup include: Apply a two-component solvent-based baking varnish; Baking and curing are performed, and the temperature of the surface of the spray-painted thermos cup before printing does not exceed 130°C.

[0015] Compared with the prior art, this application has the following advantages: (1) Achieved synergistic improvement of adhesion and hardness: This application constructs a continuous and dense film-forming skeleton through resin, introduces strong polar amide groups with amide functional monomers to form low shrinkage crosslinking nodes, and participates in the formation of a dense crosslinking network and optimizes the rheological properties of the system. The three work together to effectively solve the technical contradiction of hardness and adhesion in traditional white ink undercoating. While significantly improving the hardness of the cured film, it ensures strong adhesion to complex substrates.

[0016] (2) Significantly enhanced alcohol resistance: This application constructs a dense white ink base layer structure through the synergistic crosslinking effect of amide functional monomers, resin, and reactive diluent, which effectively blocks the penetration of alcohol solvents and significantly improves the alcohol resistance of the coating.

[0017] (3) Improve standby anti-settling and storage stability: The reactive diluent works with the resin and amide functional monomers to build a dense cross-linked network, optimize the rheological properties of the system, effectively inhibit pigment sedimentation and agglomeration, ensure the uniformity and stability of UV white ink in storage and equipment standby state, and prevent printhead clogging. Detailed Implementation

[0018] To make the technical problems, technical solutions, and beneficial effects solved by this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0019] In this application, "alicyclic (meth)acrylate reactive diluents" refers to reactive diluents whose molecular structure contains a saturated alicyclic skeleton (such as isobornyl or cyclohexyl) or a saturated oxygen-containing heterocyclic skeleton (such as tetrahydrofuran, which is classified as an alicyclic structure in this application), and uses acrylate or methacrylate groups as polymerizable functional groups; "(meth)acrylate" is a conventional expression in the art, referring to acrylates and / or methacrylates, and does not imply that each compound contains α-methyl. Representative examples include, but are not limited to: isobornyl acrylate, isobornyl methacrylate, tetrahydrofuran methyl acrylate, and tert-butylcyclohexyl acrylate.

[0020] This application provides a UV white ink, the raw materials for which, by weight, are: 5-10 parts resin; 30-40 parts of amide functional monomers; 25-40 parts of reactive diluent; 5-10 parts of photoinitiator; Contains 10-25 parts of titanium dioxide powder; Additives: 0.3-3 parts.

[0021] In this embodiment, the UV white ink, through the synergistic effect of multiple components such as resin, amide functional monomers, and reactive diluents, utilizes the matching effect of polarity and crosslinking kinetics to construct a dense crosslinked network with both high interfacial bonding strength and high bulk toughness. Specifically, the resin provides the film-forming framework and anchoring points; the amide functional monomers, through the synergy of their strong polar amide bonds and photopolymerizable double bonds, construct highly cohesive, low-shrinkage crosslinking nodes in the cured network, thereby dispersing internal stress, improving toughness, and balancing hardness and flexural resistance; the reactive diluent precisely adjusts the system viscosity and participates in the crosslinking reaction, forming a dense film layer together with the aforementioned components. Combined with a photoinitiator for efficient curing, titanium dioxide-containing pigments for opacity, and additives for surface leveling and interfacial transition, the multi-component synergistic effect adapts to the diverse requirements of adhesion, weather resistance, and industrial mass production stability in complex cylindrical curved surface printing.

[0022] In some embodiments, the resin includes at least one of aldehyde-ketone resin, polyester resin, and pure acrylic resin.

[0023] In the embodiments of this application, the aldehyde-ketone resin, with its abundant carbonyl and terminal hydroxyl groups in its molecular chain, efficiently wets and disperses TiO2, ensuring the excellent storage stability and standby anti-sinking performance of the UV white ink. On the other hand, it significantly enhances the interfacial bonding force between the white ink underlay and low surface energy substrates such as PET and metal. The polyester resin, through the synergy of flexible segments and polar ester groups, endows the white ink underlay with excellent resistance to thermal shock and scratch resistance, preventing the ink layer from cracking and warping during curved surface printing. The pure acrylic resin further provides high hardness, scratch resistance and alcohol resistance, and precisely controls the ink rheological behavior to ensure the long standby smoothness of industrial piezoelectric printheads (such as Ricoh G5i).

[0024] When aldehyde-ketone resin, polyester resin, and pure acrylic resin are combined in pairs: aldehyde-ketone resin and polyester resin help improve adhesion and scratch resistance, solving problems such as peeling and thermal cracking on low surface energy substrates; aldehyde-ketone resin and pure acrylic resin help balance high hardness, alcohol resistance, and long standby time to prevent clogging; polyester resin and pure acrylic resin help build a high-hardness, flexible, and chemically resistant ink layer framework. When aldehyde-ketone resin, polyester resin, and pure acrylic resin are blended, they help further balance adhesion, hardness, scratch resistance, alcohol resistance, standby anti-sinking properties, and UV white ink viscosity-rheology, to meet the diverse needs of complex cylindrical curved surface printing for adhesion, weather resistance, and industrial mass production stability.

[0025] In some embodiments, the glass transition temperature of the aldehyde-ketone resin is 45-70°C, for example 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, and temperatures between any two of the above values.

[0026] In some embodiments, the glass transition temperature of the polyester resin is 40-80°C, for example 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 80°C, and temperatures between any two of the above values.

[0027] In some embodiments, the weight-average molecular weight of the pure acrylic resin is 30,000-120,000 g / mol, for example 30,000 g / mol, 40,000 g / mol, 50,000 g / mol, 60,000 g / mol, 70,000 g / mol, 80,000 g / mol, 90,000 g / mol, 100,000 g / mol, 110,000 g / mol, or 120,000 g / mol.

[0028] In some embodiments, the aldehyde-ketone resin includes BASF's Laropal A81, Laropal A101, and Evonik's Alberdingk. ® At least one of the following: AP series aldehyde-ketone resins (such as AP 234), Yantai Mangosteen aldehyde-ketone resin A81 type (such as UVSZ81), Jinan Yuantiao aldehyde-ketone resin KR-UVA81, Jinan Changtai CT-AP aldehyde-ketone resin, and Yueyang Dongrun aldehyde-ketone resin LHR-UV81.

[0029] In some embodiments, the polyester resin includes at least one of Toyobo VYLON 200, VYLON 270, DSM CRYLCOAT 1781, Miki S-91, Huayuan HY-881, Qingtian YM287, Jingtu PS-16, and Evonik LTH polyester resin (such as LTH-612).

[0030] In some embodiments, the pure acrylic resin includes Covestro NeoCryl ® At least one of B-302, Elvacite4026, Mitsubishi MB-7143, Bolier BM112A, BM55F, and BM56A.

[0031] In some embodiments, the mass ratio of the resin to the amide functional monomer is 0.14-0.35. At this ratio, the amide functional monomer forms a strong adsorption layer on the surface of TiO2 particles, ensuring the standby anti-settling properties of the UV white ink, and also synergistically crosslinks with the resin, giving the white ink underlay good cross-cut adhesion to metals, PET, powder coatings, etc., while maintaining suitable pencil hardness and scratch resistance. Furthermore, a moderate crosslinking density also helps improve the alcohol resistance of the white ink underlay.

[0032] In some embodiments, the mass ratio of the amide functional monomer to the reactive diluent is 1-1.3. It is understood that by controlling the mass ratio of the amide functional monomer to the reactive diluent to 1-1.3, polymerization shrinkage can be reduced while ensuring rapid UV curing, the adhesion of the white ink underlay (containing titanium dioxide paste) to the thermos cup can be improved, and the wetting and dispersibility of TiO2 can be enhanced, thereby preventing the white ink underlay from cracking or peeling during curved surface printing and use.

[0033] In some embodiments, the amide functional monomers include acrylamide monofunctional monomers and N-vinyl lactam monofunctional monomers.

[0034] In some embodiments, the acrylamide monofunctional monomer includes at least one of N,N-dimethylacrylamide (DMAA), N,N-diethylacrylamide (DEAA), and acrylmorpholine (ACMO); The N-vinyllactam monofunctional monomers include at least one of N-vinyl-2-pyrrolidone (NVP) and N-vinylcaprolactam (NVCL).

[0035] In this embodiment, by introducing acrylamide-based monofunctional monomers (such as acrylomorpholine, N,N-dimethylacrylamide, and N,N-diethylacrylamide), the free radical polymerization activity can be improved, resulting in good copolymerization with reactive diluents, reducing UV curing volume shrinkage, and improving the flexibility of the white ink underlay, thus reducing the risk of cracking during printing on curved surfaces of thermos cups and during use. By jointly introducing N-vinyllactam-based monofunctional monomers (such as N-vinyl-2-pyrrolidone and N-vinylcaprolactam), their strong polarity and good wettability on TiO2 surfaces improve the dispersion stability of TiO2 particles in UV white ink, preventing TiO2 particles from settling during storage and enhancing the adhesion between white ink underlay layers. The synergistic effect of these two methods allows the UV white ink to achieve both rapid curing and low shrinkage while maintaining good TiO2 dispersion and adhesion to cylindrical curved substrates, making it particularly suitable for cylindrical curved surface inkjet printing processes.

[0036] In some embodiments, the reactive diluent includes at least one of alicyclic (meth)acrylate reactive diluents and non-alicyclic (meth)acrylate reactive diluents.

[0037] In some embodiments, the alicyclic (meth)acrylate reactive diluent includes at least one of isobornyl acrylate (IBOA), isobornyl methacrylate (IBOMA), tetrahydrofuran methyl acrylate (THFA), and tert-butylcyclohexyl acrylate (TBCHA). The non-alicyclic (meth)acrylate reactive diluent includes at least one of 1,6-hexanediol diacrylate (HDDA), 1,6-hexanediol dimethacrylate (HDDM), and dipropylene glycol acrylate (DPPA).

[0038] In the embodiments of this application, alicyclic (meth)acrylate reactive diluents (such as isobornyl acrylate, isobornyl methacrylate, tetrahydrofuran methyl acrylate, and tert-butylcyclohexyl acrylate) contain rigid alicyclic structures, which can improve the hardness, abrasion resistance, and chemical resistance of the ink layer after curing, and effectively reduce polymerization shrinkage, thereby improving the adhesion and dimensional stability of the white ink underlay on cylindrical curved substrates. Non-alicyclic (meth)acrylate reactive diluents (such as 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, and dipropylene glycol acrylate) have lower viscosity and higher double bond density, providing rapid curing capability and crosslinking density, improving ink leveling and printability. Alicyclic (meth)acrylate reactive diluents and non-alicyclic (meth)acrylate reactive diluents can be used alone or in combination to achieve a balance between adhesion, hardness, and crosslinking density, making them suitable for inkjet printing on cylindrical curved surfaces.

[0039] In some embodiments, the photoinitiator includes at least one of ethyl 2,4,6-trimethylbenzoylphenylphosphonate (TPO-L), (2,4,6-trimethylbenzoyl)bis(p-tolyl)phosphine oxide (TMO), (2,4,6-trimethylbenzoyl)diphenylphosphine oxide (TPO), and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (819).

[0040] In some embodiments, the titanium dioxide content in the titanium dioxide-containing slurry is 50-70%, and the average particle size is 200-300 nm.

[0041] In some embodiments, the additives include at least one of leveling agents and polymerization inhibitors.

[0042] In some embodiments, the leveling agent includes at least one of BYK333, BYK371, BYK373, BYK377, BYK378, and BYK3700, used to improve the wetting and spreading properties of UV white ink on the surface of a thermos substrate and reduce pinholes and orange peel.

[0043] In some embodiments, the polymerization inhibitor is a phenolic polymerization inhibitor (phenolic free radical polymerization inhibitor), such as Genorad™ 22, used to inhibit thermally initiated polymerization of UV white ink during storage and transportation, thereby ensuring ink stability.

[0044] By using a combination of polymerization inhibitors and leveling agents, it is possible to ensure rapid UV curing while also maintaining ink storage stability and smooth printing.

[0045] This application further provides a method for preparing UV white ink as described in any of the above embodiments, comprising the following steps: Mix 5-10 parts by weight of resin with 25-40 parts by weight of reactive diluent, add 30-40 parts by weight of amide functional monomer, 5-10 parts by weight of photoinitiator and 0.3-3 parts by weight of additives, stir, then add 10-25 parts by weight of titanium dioxide pigment paste, stir, filter, and obtain the UV white ink.

[0046] This application embodiment also provides an application process for UV white ink as described in any of the above claims in cylindrical curved surface decoration printing, the application process including the following steps: The UV white ink is deposited onto the cylindrical curved surface using inkjet printing to form a wet white ink underlayer. The wet white ink underlay was cured using an LED-UV light source with a wavelength of 365 nm-405 nm to obtain a cured white ink underlay. The curing process uses an irradiation energy of 200-300 mJ / cm². 2 The dry film thickness of the white ink underlayer is 10-15 μm.

[0047] In some embodiments, the cylindrical curved surface is the surface of a powder-coated thermos cup and / or the surface of a painted thermos cup; When the cylindrical curved surface is the surface of a powder-coated insulated cup, the surface treatment steps of the powder-coated insulated cup include: Electrostatic spraying with polyester / epoxy powder was used to control the thickness of the powder coating layer to be 60-100 μm. The surface of the powder-coated thermos cup is baked and cured, and the baking temperature before printing is 160-180℃. When the cylindrical curved surface is the surface of a spray-painted thermos cup, the processing steps for the surface of the spray-painted thermos cup include: Apply a two-component solvent-based baking varnish; Baking and curing are performed, and the temperature of the surface of the spray-painted thermos cup before printing does not exceed 130°C.

[0048] To further illustrate the technical effects of this application, the following specific embodiments are also provided.

[0049] Example 1 Example 1 provides a UV white ink, the preparation method of which includes the following steps: Five parts by weight of resin (aldehyde-ketone resin) were mixed with reactive diluent (five parts by weight of HDDA, five parts by weight of THFA, ten parts by weight of IBOA, and 12.2 parts by weight of TBCHA), amide functional monomers (ten parts by weight of ACMO, 15 parts by weight of NVP, and ten parts by weight of DMAA), photoinitiator (five parts by weight of TPO and two parts by weight of 819), and additives (0.5 parts by weight of silicone leveling agent and 0.3 parts by weight of phenolic polymerization inhibitor). The mixture was stirred, and then 20 parts by weight of titanium dioxide-containing pigment paste (TiO2 solid content 60 wt%) was added. The mixture was dispersed at high speed and filtered through a filter membrane to obtain UV white ink.

[0050] Except for the formulations shown in Table 1 (Examples) and Table 2 (Comparative Examples), the other operations were the same as the preparation method of Example 1, and UV white inks of Examples 2-9 and Comparative Examples 1-5 were prepared respectively.

[0051] Table 1. Formulations for Examples 1-9 (parts by mass)

[0052] Table 2 Formulations for Comparative Examples 1-5 (unit: parts by mass)

[0053] For the UV white inks prepared in Examples 1-9 and Comparative Examples 1-5, their viscosity was first tested. Then, the inks were deposited on the outer curved surface of the thermos cup using inkjet printing to form a wet white ink underlay. The wet white ink underlay was cured using an LED-UV light source with a wavelength of 395 nm and the irradiation energy was set to 300 mJ / cm². 2 The cured white ink underlayer was obtained with a dry film thickness of 10 μm. Performance tests were performed on the cured white ink underlayer, and the results (including the viscosity of the UV white ink) are shown in Table 3.

[0054] Table 3 Test Results

[0055] Note: (1) Cross-cut adhesion: Perform a 1mm×1mm cross-cut test according to ASTM D3359 standard. After peeling off the tape, the area of ​​peeling off is less than 5% and there is no peeling at the edge.

[0056] (2) Pencil hardness: A pencil hardness tester was used to apply a 750g load for testing. The test was considered to be qualified if the hardness was ≥2H and there were no scratches.

[0057] (3) Dishwasher resistance: The product is circulated in a dishwasher environment at 65℃, with each cycle lasting 30 minutes. After a total of 25 cycles, the product is considered qualified if there is no abnormality in adhesion.

[0058] (4) Alcohol resistance: Wipe the coating 50 times with a cotton cloth soaked in 75% ethanol. The coating is considered qualified if it does not change color, lose gloss or fade.

[0059] (5) Printhead standby stability: After the printhead is suspended and left to standby for 20 minutes, a printing test is performed. The test strip is considered to be qualified if there are no broken lines or missing ink.

[0060] (6) Ink viscosity: The viscosity is tested at 25°C using a cone-plate viscometer, and a viscosity value of 10-12 mPa·s is considered acceptable.

[0061] As shown in Table 3, Examples 1-9 all passed all performance tests within the specified mixing ratio range, demonstrating excellent overall adaptability and stable application in printing on curved surfaces of thermos cups. Comparative Example 1, due to resin deficiency, had insufficient film-forming skeleton and interface anchoring points, resulting in substandard cross-cut adhesion and dishwasher resistance. Comparative Example 2, with a resin content below 5 parts by weight, had insufficient interface anchoring strength, also resulting in substandard cross-cut adhesion and dishwasher resistance. Comparative Example 3, with a resin content above 10 parts by weight, had excessively high system viscosity, causing excessive viscosity of the UV white ink and printhead standby performance failure. Comparative Example 4, lacking amide functional monomers, could not construct high-cohesion, low-shrinkage cross-linking nodes, resulting in insufficient stress dispersion within the system. Although initial hardness and adhesion were acceptable, printhead standby performance significantly decreased, failing to meet industrial continuous printing requirements. Comparative Example 5, with amide functional monomers above 40 parts by weight, disrupted the polarity and cross-linking kinetics balance with the resin, leading to a decrease in the cross-linking density or interface bonding force of the cured white ink underlayer, resulting in substandard dishwasher resistance; all other indicators met the requirements.

[0062] Compared with the prior art, this application has the following advantages: (1) Achieved synergistic improvement of adhesion and hardness: This application constructs a continuous and dense film-forming skeleton through resin, introduces strong polar amide groups with amide functional monomers to form low shrinkage crosslinking nodes, and participates in the formation of a dense crosslinking network and optimizes the rheological properties of the system. The three work together to effectively solve the technical contradiction of hardness and adhesion in traditional white ink undercoating. While significantly improving the hardness of the cured film, it ensures strong adhesion to complex substrates.

[0063] (2) Significantly enhanced alcohol resistance: This application constructs a dense white ink base layer structure through the synergistic crosslinking effect of amide functional monomers, resin, and reactive diluent, which effectively blocks the penetration of alcohol solvents and significantly improves the alcohol resistance of the coating.

[0064] (3) Improve standby anti-settling and storage stability: The reactive diluent works with the resin and amide functional monomers to build a dense cross-linked network, optimize the rheological properties of the system, effectively inhibit pigment sedimentation and agglomeration, ensure the uniformity and stability of UV white ink in storage and equipment standby state, and prevent printhead clogging.

[0065] The specific embodiments of this application have been described above. It should be understood that the scope of protection of this application is not limited thereto. Those skilled in the art should understand that any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application fall within the scope of protection and disclosure of this application.

Claims

1. A UV white ink, characterized in that, The raw materials for preparation, by weight, include: 5-10 parts resin; 30-40 parts of amide functional monomers; 25-40 parts of reactive diluent; 5-10 parts of photoinitiator; Contains 10-25 parts of titanium dioxide powder; Additives: 0.3-3 parts.

2. The UV white ink according to claim 1, characterized in that, The resin includes at least one of aldehyde-ketone resin, polyester resin, and pure acrylic resin.

3. The UV white ink according to claim 2, characterized in that, The glass transition temperature of the aldehyde-ketone resin is 45-70℃; and / or The glass transition temperature of the polyester resin is 40-80℃; and / or The weight-average molecular weight of the pure acrylic resin is 30,000-120,000 g / mol.

4. The UV white ink according to claim 1, characterized in that, The mass ratio of the resin to the amide functional monomer is 0.14-0.35; and / or The mass ratio of the amide functional monomer to the reactive diluent is 1-1.

3.

5. The UV white ink according to claim 1, characterized in that, The amide functional monomers include acrylamide monofunctional monomers and N-vinyl lactam monofunctional monomers.

6. The UV white ink according to claim 1, characterized in that, The reactive diluent includes at least one of alicyclic (meth)acrylate reactive diluents and non-alicyclic (meth)acrylate reactive diluents.

7. The UV white ink according to claim 1, characterized in that, The photoinitiator comprises at least one of ethyl 2,4,6-trimethylbenzoylphenylphosphonate, (2,4,6-trimethylbenzoyl)bis(p-tolyl)phosphine oxide, (2,4,6-trimethylbenzoyl)bis(2,4,6-trimethylbenzoyl)phosphine oxide, and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide; and / or The titanium dioxide-containing slurry has a titanium dioxide solid content of 50-70% and an average particle size of 200-300 nm; and / or The additives include at least one of leveling agents and polymerization inhibitors.

8. A method for preparing a UV white ink as described in any one of claims 1-7, characterized in that, Includes the following steps: Mix 5-10 parts by weight of resin with 25-40 parts by weight of reactive diluent, add 30-40 parts by weight of amide functional monomer, 5-10 parts by weight of photoinitiator and 0.3-3 parts by weight of additives, stir, then add 10-25 parts by weight of titanium dioxide pigment paste, stir, filter, and obtain the UV white ink.

9. A process for applying UV white ink as described in any one of claims 1-7 in the decorative printing of cylindrical curved surfaces, characterized in that, The application process includes the following steps: The UV white ink is deposited onto the cylindrical curved surface using inkjet printing to form a wet white ink underlayer. The wet white ink underlay was cured using an LED-UV light source with a wavelength of 365 nm-405 nm to obtain a cured white ink underlay. The curing process uses an irradiation energy of 200-300 mJ / cm². 2 The dry film thickness of the white ink underlayer is 10-15 μm.

10. The application process according to claim 9, characterized in that, The cylindrical curved surface is the surface of a powder-coated thermos cup and / or the surface of a painted thermos cup; When the cylindrical curved surface is the surface of a powder-coated insulated cup, the surface treatment steps of the powder-coated insulated cup include: Electrostatic spraying with polyester / epoxy powder was used to control the thickness of the powder coating layer to be 60-100 μm. The surface of the powder-coated thermos cup is baked and cured, and the baking temperature before printing is 160-180℃. When the cylindrical curved surface is the surface of a spray-painted thermos cup, the processing steps for the surface of the spray-painted thermos cup include: Apply a two-component solvent-based baking varnish; Baking and curing are performed, and the temperature of the surface of the spray-painted thermos cup before printing does not exceed 130°C.

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