Digital jet printing ink for glass substrate, preparation method and jet printing method

Abstract

The invention discloses digital jet printing ink for a glass substrate and a preparation method and a jet printing method.The digital jet printing ink for the glass substrate is prepared from, by weight, 20-40 parts of hydroxyl-containing modified acrylic resin, 40-60 parts of active monomers, 5-15 parts of isocyanate, 5-10 parts of photoinitiator and 1-10 parts of pigment, the viscosity of the digital jet printing ink at 25 DEG C is 10mPa. S to 30mPa. S, and the particle size of solid particles in the ink is less than 0.5 mu m. The digital jet printing ink provided by the invention overcomes the problem of poor adhesion of digital jet printing ink on glass, and has excellent adhesion on a glass substrate.

Description

Technical Field

[0001] This invention relates to the field of digital inkjet printing technology, and particularly to digital inkjet printing inks for glass substrates, their preparation methods, and printing methods. Background Technology

[0002] Digital inkjet printing can accurately and on-demand print patterns and text on regular or irregular material surfaces such as flat and curved surfaces. It has low ink consumption, requires no plate making, and has no VOC (volatile organic compounds) emissions. It can provide a wider color gamut and more delicate color gradations. It is the most economical and environmentally friendly material surface treatment method to replace traditional methods such as gravure printing, letterpress printing, screen printing, transfer printing, roller coating, spin coating, and spraying. It can also bring benefits such as high efficiency, high precision, and full automation.

[0003] However, digital inkjet inks have low viscosity and small solid particle size, requiring good flowability to adapt to the fine printheads of digital printers. As a result, when digital inkjet inks are used on glass substrates, the ink adhesion is poor. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides digital inkjet printing inks for glass substrates, their preparation methods, and printing methods, aiming to solve the problem of poor ink adhesion when digital inkjet printing inks are applied to glass substrates.

[0005] To achieve the above objectives, the present invention proposes a digital inkjet printing ink for glass substrates. By weight, the raw materials of the digital inkjet printing ink include: 20 to 40 parts of hydroxyl-modified acrylic resin, 40 to 60 parts of reactive monomer, 5 to 15 parts of isocyanate, 5 to 10 parts of photoinitiator, 1 to 10 parts of pigment, and 1 to 10 parts of additives. The viscosity of the digital inkjet printing ink at 25°C is 10 mPa·s to 30 mPa·s, and the particle size of the solid particles in the ink is <0.5 μm.

[0006] In some embodiments, the hydroxyl-containing modified acrylic resin includes a hydroxyl-containing difunctional epoxy acrylate, wherein the hydroxyl-containing difunctional epoxy acrylate has a viscosity of 500 mPa·s to 3000 mPa·s at 25°C.

[0007] In some embodiments, the active monomer comprises a monomer containing an epoxy group and / or a hydroxyl group.

[0008] In some embodiments, the active monomer includes at least one of hydroxyethyl acrylate, hydroxyethyl phosphate acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, glycidyl methacrylate, glycidyl acrylate, and glycidyl neodecanoate.

[0009] In some embodiments, the photoinitiator comprises at least one of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2,4,6-trimethylbenzoyl-phenylethoxyphosphine oxide, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-hydroxycyclohexylphenyl ketone, 2-isopropylthioxanthone, (2,4,6-trimethylbenzoyl)phenylphosphine oxide, and 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone; and / or, the adjuvant comprises at least one of a dispersant, defoamer, coupling agent, leveling agent, and polymerization inhibitor.

[0010] To achieve the above objectives, the present invention also proposes a method for preparing digital inkjet printing ink for glass substrates, comprising the following steps: mixing an active monomer, a dispersant, and an antifoaming agent and stirring for the first time; adding pigment and stirring for the second time to obtain a mixture; then dispersing the mixture by grinding and filtering for the first time to obtain a color paste; adding a hydroxyl-modified acrylic resin, a photoinitiator, an isocyanate, a leveling agent, a coupling agent, and a polymerization inhibitor to the color paste; and then stirring for the third time and filtering for the second time to obtain digital inkjet printing ink for glass substrates.

[0011] In some embodiments, the volume ratio of zircon sand to the mixture in the abrasive dispersion is (1~2):1, and the particle size of the zircon sand is 0.2mm~0.4mm; and / or, the first filtration includes sequential filtration with a precision of 5μm, 2μm, and 0.5μm; and / or, the second filtration includes filtration with a precision of 0.5μm.

[0012] In some embodiments, the stirring speed of the first stirring is 300 rpm to 500 rpm, and the stirring time is 5 min to 10 min; and / or, the stirring speed of the second stirring is 2500 rpm to 3000 rpm, and the stirring time is 2 h to 4 h; and / or, the stirring speed of the third stirring is 300 rpm to 500 rpm, and the stirring time is 10 min to 20 min.

[0013] To achieve the above objectives, the present invention also proposes a printing method for digital inkjet ink on a glass substrate, the printing method comprising digitally spraying the digital inkjet ink onto the glass substrate and curing it, the curing comprising ultraviolet light curing followed by baking curing.

[0014] In some embodiments, the ultraviolet light curing is at 800 mJ / cm 2 ~1600mJ / cm 2 The baking and curing process is carried out at a temperature of 140°C to 170°C.

[0015] The beneficial effects of this invention are: In terms of physical characteristics, the digital inkjet printing ink provided by this invention has low viscosity, which is conducive to the precise formation and spraying of ink droplets. After being sprayed onto the glass surface, it can quickly level and fully wet the substrate surface, ensuring that the ink and glass achieve maximum contact area. The solid particles are mainly pigments, and the small particles can minimize physical defects and stress concentration points at the ink / glass substrate interface, resulting in a stronger interface bond.

[0016] In terms of chemical material selection, hydroxyl-modified acrylic resins contain acrylate groups and hydroxyl groups. Under sufficient photoinitiator action, they undergo thorough UV curing with active monomers to form a cross-linked network with good toughness and high cohesive strength. The participation of isocyanate in thermosetting further improves the cross-linking density and network strength. Under high-temperature conditions, hydroxyl-containing substances can undergo cross-linking reactions with end-capped isocyanates. Furthermore, difunctionality means that each molecule has two acrylate double bonds that can participate in curing. This provides sufficient cross-linking density to ensure the hardness, toughness, and toughness of the ink film, helping to resist stress caused by temperature changes in the glass substrate and preventing the ink film from cracking and peeling.

[0017] In this solution, the strong adhesion of digital inkjet printing on glass substrates is the result of the synergistic effect of the above features, which enables the ink coating to withstand the friction, thermal cycling, moisture or chemical contact common in the inkjet printing environment. Detailed Implementation

[0018] To make the technical solutions and advantages of the present invention clearer, the present invention and its beneficial effects will be described in further detail below in conjunction with specific embodiments. The following description is provided to enable those skilled in the art to fully understand this application and is not intended to limit the subject matter recorded in the claims.

[0019] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0020] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0021] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0022] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0023] Digital inkjet printing can accurately and on-demand print patterns and text on regular or irregular material surfaces such as flat and curved surfaces. It has low ink consumption, requires no plate making, and has no VOC (volatile organic compounds) emissions. It can provide a wider color gamut and more delicate color gradations. It is the most economical and environmentally friendly material surface treatment method to replace traditional methods such as gravure printing, letterpress printing, screen printing, transfer printing, roller coating, spin coating, and spraying. It can also bring benefits such as high efficiency, high precision, and full automation.

[0024] However, digital inkjet inks have low viscosity and small solid particle size, requiring good flowability to adapt to the fine printheads of digital printers. As a result, when digital inkjet inks are used on glass substrates, the ink adhesion is poor.

[0025] In view of this, the present invention proposes a digital inkjet printing ink for glass substrates. By weight, the raw materials of the digital inkjet printing ink include: 20 to 40 parts of hydroxyl-modified acrylic resin, 40 to 60 parts of reactive monomer, 5 to 15 parts of isocyanate, 5 to 10 parts of photoinitiator, 1 to 10 parts of pigment, and 1 to 10 parts of additives. The viscosity of the digital inkjet printing ink at 25°C is 10 mPa·s to 30 mPa·s, and the particle size Dv50 of the solid particles in the digital inkjet printing ink is < 0.5 μm.

[0026] In terms of physical characteristics, the digital inkjet printing ink of this solution has low viscosity, which is conducive to the precise formation and spraying of ink droplets. After being sprayed onto the glass surface, it can quickly level and fully wet the substrate surface, ensuring that the ink and glass achieve maximum contact area. The solid particles are mainly pigments, and the small particles can minimize physical defects and stress concentration points at the ink / glass substrate interface, resulting in a stronger interface bond.

[0027] In terms of chemical material selection, the modified acrylic resin containing hydroxyl groups contains acrylate groups and hydroxyl groups. Under the action of sufficient photoinitiator, it is fully UV cured with active monomers to form a cross-linked network with good toughness and high cohesive strength. The participation of isocyanate in thermosetting further improves the cross-linking density and network strength. Under high temperature conditions, it can undergo cross-linking reaction with the end-capped isocyanate. In addition, the difunctionality means that each molecule has two acrylate double bonds that can participate in curing. This provides sufficient cross-linking density to ensure the hardness, toughness and toughness of the ink film, which helps to resist the stress caused by temperature changes in the glass substrate and prevent the ink film from cracking and peeling.

[0028] In this solution, the strong adhesion of digital inkjet printing on glass substrates is the result of the synergistic effect of the above features, which enables it to withstand friction, cleaning, hot and cold cycles, and even certain moisture or chemical contact common in glass inkjet printing environments.

[0029] In some embodiments, the hydroxyl-containing modified acrylic resin includes at least one of polyester-modified hydroxyl acrylic resin, hydroxyl-containing polyether acrylic resin, hydroxyl-containing difunctional epoxy acrylic resin, and hydroxyl-containing polyurethane acrylic resin. Preferably, the hydroxyl-containing modified acrylic resin includes a hydroxyl-containing difunctional epoxy acrylic resin.

[0030] In some embodiments, the pigment includes at least one of phthalocyanine blue, titanium dioxide, phthalocyanine green, pigment red 122, pigment red 264, pigment yellow 150, pigment yellow 74, and carbon black.

[0031] In some embodiments, the viscosity at 25°C is preferably 10 mPa·s to 15 mPa·s.

[0032] In some embodiments, the hydroxyl-containing modified acrylic resin includes a hydroxyl-containing difunctional epoxy acrylate, wherein the hydroxyl-containing difunctional epoxy acrylate has a viscosity of 500 mPa·s to 3000 mPa·s at 25°C.

[0033] Bifunctional epoxy acrylates have a high viscosity, but digital inkjet printing requires extremely low ink viscosity. This solution limits the range of bifunctional epoxy acrylates and combines it with a large amount of low-viscosity active monomers in the ink formulation, allowing the active monomers to act as both crosslinking raw materials and diluents. Furthermore, in this solution, bifunctionality provides a rapid curing rate while avoiding brittleness caused by excessive crosslinking. In some embodiments, the viscosity of the bifunctional epoxy acrylate at 25°C is preferably 500 mPa·s to 500 mPa·s.

[0034] In some embodiments, the functional groups of the active monomer include acrylate groups and epoxy groups, acrylate groups and hydroxyl groups, acrylate groups and siloxane groups, acrylate groups and phosphate groups, acrylate groups and ether bonds, etc.

[0035] In some embodiments, the active monomers include isobornyl acrylate, tetrahydrofurfuryl acrylate, phenoxyethyl acrylate, pentaerythritol tetraacrylate, ethoxyethoxyethyl acrylate, cyclotrimethylolpropane methyl acetal acrylate, 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, ethoxytrimethylolpropane triacrylate, hydroxyethyl acrylate, 2-ethylacryloyloxymethyl phosphate, hydroxyethyl phosphate, etc.

[0036] In some embodiments, the active monomer is preferably a monomer containing an epoxy group and / or a hydroxyl group.

[0037] In some embodiments, under UV irradiation, epoxy monomers can undergo ring-opening polymerization via cationic initiators, complementing the free radical curing of acrylates and improving deep curing efficiency. Furthermore, the volume shrinkage rate of ring-opening polymerization is lower than that of free radical polymerization of acrylates, reducing the risk of warping and delamination, and lowering shrinkage stress. In some embodiments, the reaction of hydroxyl monomers with isocyanates can generate flexible segments, resolving the brittleness problem caused by potential high-crosslinking side reactions while maintaining high hardness.

[0038] In some embodiments, the active monomer preferably includes two or more monomers containing epoxy groups and hydroxyl groups.

[0039] In some embodiments, the active monomer includes at least one of hydroxyethyl acrylate, hydroxyethyl phosphate acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, glycidyl methacrylate, glycidyl acrylate, and glycidyl neodecanoate.

[0040] In some embodiments, the active monomer preferably includes at least one of the following: hydroxyethyl acrylate and glycidyl acrylate in a mass ratio of 2:1; glycidyl acrylate and hydroxyethyl phosphate acrylate in a mass ratio of 1:1; and tetrahydrofuran acrylate and neodecanoic acid glycidyl ester in a mass ratio of 1:1. The combined active monomers can achieve a balance in adhesion, hardness, chemical resistance, alcohol resistance, and viscosity after crosslinking with difunctional epoxy acrylates and isocyanates.

[0041] In some embodiments, the photoinitiator comprises at least one selected from 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2,4,6-trimethylbenzoyl-phenylethoxyphosphine oxide, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-hydroxycyclohexylphenyl ketone, 2-isopropylthioxanthanone, (2,4,6-trimethylbenzoyl)phenylphosphine oxide, and 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone. Preferably, the photoinitiator comprises (2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2,4,6-trimethylbenzoyl-phenylethoxyphosphine oxide, and 2-isopropylthioxanthanone. Preferably, the photoinitiator is present in the ink in parts by weight of 5 to 7.5 parts.

[0042] The additives include at least one of dispersants, defoamers, coupling agents, leveling agents, and polymerization inhibitors. The additives ensure uniform dispersion of pigments in the ink, preventing sedimentation and reaction during long-term storage at room temperature, in a sealed, light-protected environment. During printing, the ink exhibits good leveling properties, free from bubbles, pinholes, and thick edges, and the cured ink surface has a pleasant feel.

[0043] In some embodiments, the additives include dispersants, defoamers, coupling agents, leveling agents, and polymerization inhibitors. The dispersants, defoamers, coupling agents, leveling agents, and polymerization inhibitors can be conventionally selected in conjunction with the final room temperature (25°C) viscosity of the ink product specified in this formulation. It should be noted that regardless of the conventional selection of additives, the overall ink formulation has the beneficial effects claimed above.

[0044] To address the aforementioned problems, the present invention also proposes a method for preparing the above-mentioned digital inkjet printing ink for glass substrates, comprising the following steps: S1: Mix the active monomer, dispersant, and defoamer, stir for the first time, add the pigment and stir for the second time to obtain a mixture, then disperse by grinding and filter for the first time to obtain a color paste; S2: Add hydroxyl-modified acrylic resin, leveling agent, coupling agent, and polymerization inhibitor to the color paste, and after a third stirring and a second filtration, obtain digital inkjet printing ink for glass substrates.

[0045] This method employs a process of first preparing the pigment paste and then mixing it with the ink. Multiple stirring and two filtrations ensure stable pigment suspension, resulting in inks with good batch-to-batch stability and reliable performance, suitable for the stringent requirements of industrial production and digital inkjet printing. The polymerization inhibitor added in step S2 prevents premature polymerization and curing of the ink during storage and within the printhead due to factors such as heat or trace amounts of oxygen.

[0046] In some embodiments, the active monomer and the hydroxyl-containing modified acrylic resin are selected from the compounds mentioned above, and the dispersant, defoamer, leveling agent, coupling agent, and polymerization inhibitor can be selected in accordance with industry practice to suit the resin matrix and the active monomer.

[0047] In some embodiments, preferably, the dispersant includes polyvinylpyrrolidone, alkylphenol polyoxyethylene ether, etc.; the defoamer includes polyether-modified acrylate EFKA-2022; the leveling agent includes polyether-modified polysiloxane BYK-333, low molecular weight acrylic copolymer BYK-354, etc.; the coupling agent includes epoxy-based, acryloyl-based, etc.; and the polymerization inhibitor includes phenothiazine, p-hydroxyanisole, etc.

[0048] In some embodiments, the volume ratio of zircon sand to the mixture in the abrasive dispersion is (1~2):1, and the particle size of the zircon sand is 0.2mm~0.4mm; the first filtration includes sequential filtration with a precision of 5μm, 2μm, and 0.5μm; the second filtration includes filtration with a precision of 0.5μm.

[0049] Zirconium sand has a high density and generates strong kinetic energy under high-speed stirring, applying high-intensity shear and impact forces to pigment agglomerates, rapidly breaking up large particles. Preferably, the volume ratio of zirconium sand to the mixture is 1.5:1. The two filtration processes include: S1 filtration to remove coarse particles and ensure the quality of the pigment paste; and S2 final filtration to remove any impurities that may be introduced and bubbles or flocculants generated by stirring, ensuring the purity of the final ink and printing performance.

[0050] In some embodiments, the stirring speed for the first stirring is 300 rpm to 500 rpm, and the stirring time is 5 min to 10 min; the stirring speed for the second stirring is 2500 rpm to 3000 rpm, and the stirring time is 2 h to 4 h; the stirring speed for the third stirring is 300 rpm to 500 rpm, and the stirring time is 10 min to 20 min. Combined with the grinding and filtration processes, under the above stirring conditions, the ink exhibits excellent dispersion stability, which is beneficial for further applications.

[0051] To address the aforementioned problems, the present invention also proposes a printing method for the aforementioned digital inkjet ink used on a glass substrate, wherein the printing method includes digitally spraying the digital inkjet ink onto the glass substrate and curing it, wherein the curing includes ultraviolet light curing followed by baking curing.

[0052] The active monomers and numerical host in the ink undergo free radical polymerization under the action of photoinitiator to form a polymer network skeleton, and the ink film initially hardens to avoid dripping or deformation on the glass; high-temperature baking and curing of hydroxyl crosslinking and siloxane bonding of coupling agent achieve deep crosslinking and adhesion enhancement.

[0053] In some embodiments, the ultraviolet light curing is at 800 mJ / cm 2 ~1600mJ / cm 2 The baking and curing process is carried out at a temperature of 140℃~170℃.

[0054] In some embodiments, UV curing is performed using a 395 LED UV curing lamp.

[0055] In some embodiments, the baking and curing temperature is 150°C and the baking time is 1 hour.

[0056] In some embodiments, the baking and curing steps are as follows: baking at 150°C for half an hour, baking at 160°C for 20 minutes, and baking at 170°C for 10 minutes. Baking at 150°C for half an hour allows heat to be evenly transferred from the glass substrate to the entire ink film, enabling the reaction between isocyanate and hydroxyl groups to begin smoothly and avoiding the formation of bubbles or stress inside the ink film due to excessively rapid reaction; the reaction at 160°C for 20 minutes is the main reaction stage, where the temperature rises to accelerate the reaction, allowing most of the isocyanate to participate in the reaction and form a highly cross-linked network structure; the reaction at 170°C for 10 minutes is the post-curing stage, ensuring complete reaction, eliminating unreacted small molecules, and making the cross-linked network more complete and robust.

[0057] Glass is an inert surface, making it difficult for ink to adhere. The groups in the urethane bonds formed by the reaction of isocyanate and hydroxyl groups can form strong hydrogen bonds with the silanol groups on the glass surface, greatly improving adhesion. Stepped heating and baking cause the ink film to shrink slowly, reducing internal stress caused by rapid UV curing and preventing the ink film from peeling off the glass surface.

[0058] The technical solution of the present invention will be further described in detail below with reference to specific embodiments.

[0059] Example 1 S1: By weight, add 30 parts hydroxyethyl acrylate, 20 parts isobornyl acrylate, 1 part dispersant, and 0.5 parts defoamer to the reaction vessel and stir for 5-10 minutes at a stirring speed of 300-500 rpm. Add the pigment and continue stirring for 10 minutes. Add the above mixture to a sand mill and disperse at high speed for 2-4 hours at a high speed of 2500-3000 rpm. The zircon sand in the sand mill has a particle size of 0.4 mm, and the volume ratio of zircon sand to the ink mixture is 1.5:1. After dispersion, filter the mixture sequentially through 5 μm, 2 μm, and 0.5 μm filters or filter cartridges to obtain nano-sized color paste. S2: Add the dispersed pigment paste to another reactor, then add 30 parts of difunctional epoxy acrylate (viscosity 500 mPa·s at 25℃), 5 parts of (2,4,6-trimethylbenzoyl)phenylphosphine oxide, 15 parts of isocyanate, 0.5 parts of leveling agent, 1 part of coupling agent, and 1 part of polymerization inhibitor to the above reactor. Stir for 10-20 minutes at a stirring speed of 300-500 rpm. Finally, filter with a 0.5 μm filter to obtain digital inkjet printing ink for glass substrates (viscosity 15.2 mPa·s at 25℃). The digital inkjet printing ink is sprayed onto a glass substrate (such as a glass wine bottle) and cured. The curing process includes UV curing followed by baking curing. The UV curing temperature is 1300 mJ / cm². 2 The baking and curing process is carried out in the following steps: baking at 150℃ for half an hour, baking at 160℃ for 20 minutes, and baking at 170℃ for 10 minutes.

[0060] Example 2: The raw materials for the digital inkjet printing ink include: 50 parts of isoborneol acrylate, 10 parts of 1,6-hexanediol diacrylate, 1 part of dispersant, 0.5 parts of defoamer, 5 parts of isocyanate, 8 parts of (2,4,6-trimethylbenzoyl)phenylphosphine oxide, 20 parts of difunctional epoxy acrylate (viscosity 1000 mPa·s at 25°C), 0.5 parts of leveling agent, 1 part of coupling agent, 1 part of polymerization inhibitor, and the remainder are as described in Example 1, to obtain a digital inkjet printing ink for glass substrates (viscosity 20.3 mPa·s at 25°C).

[0061] Example 3: The raw materials for the digital inkjet printing ink include: 50 parts of 1,6-hexanediol diacrylate, 1 part of dispersant, 0.5 parts of defoamer, 8 parts of isocyanate, 7 parts of 1-hydroxycyclohexylphenyl ketone, 30 parts of difunctional epoxy acrylate (viscosity 500 mPa·s at 25°C), 0.5 parts of leveling agent, 1 part of coupling agent, 1 part of polymerization inhibitor, and the remainder are as described in Example 1, to obtain a digital inkjet printing ink for glass substrates (viscosity 17.8 mPa·s at 25°C).

[0062] Example 4: The raw materials for the digital inkjet printing ink include: 30 parts of 1,6-hexanediol diacrylate, 20 parts of hydroxyethyl acrylate, 1 part of dispersant, 0.5 parts of defoamer, 12 parts of isocyanate, 8 parts of (2,4,6-trimethylbenzoyl)phenylphosphine oxide, 25 parts of difunctional epoxy acrylate (viscosity 1000 mPa·s at 25°C), 0.5 parts of leveling agent, 1 part of coupling agent, 1 part of polymerization inhibitor, and the remainder refers to Example 1, to obtain a digital inkjet printing ink for glass substrates (viscosity 24.6 mPa·s at 25°C).

[0063] Example 5: The raw materials for the digital inkjet printing ink include: 30 parts isoborneol acrylate, 25 parts glycidyl acrylate, 1 part dispersant, 0.5 parts defoamer, 10 parts isocyanate, 10 parts (2,4,6-trimethylbenzoyl)phenylphosphine oxide, 25 parts difunctional epoxy acrylate (viscosity 1000 mPa·s at 25°C), 0.5 parts leveling agent, 1 part coupling agent, 1 part polymerization inhibitor, and the remainder are as described in Example 1, resulting in a digital inkjet printing ink for glass substrates (viscosity 21.2 mPa·s at 25°C).

[0064] Example 6: The raw materials for the digital inkjet printing ink include: 45 parts glycidyl acrylate, 10 parts isobornyl acrylate, 5 parts dispersant, 0.5 parts defoamer, 12 parts isocyanate, 10 parts (2,4,6-trimethylbenzoyl)phenylphosphine oxide, 25 parts difunctional epoxy acrylate (viscosity 1500 mPa·s at 25°C), 0.5 parts leveling agent, 1 part coupling agent, 1 part polymerization inhibitor, and the remainder are as described in Example 1, resulting in a digital inkjet printing ink for glass substrates (viscosity 29.6 mPa·s at 25°C).

[0065] Example 7: The zircon sand in the sand mill has a particle size of 0.2 mm. The volume ratio of zircon sand to the ink mixture is 1:1. After dispersion, the mixture is filtered sequentially using 5 μm, 2 μm, and 0.5 μm filters or filter cartridges to obtain nanoscale color paste. After preparing the digital inkjet ink for glass substrates, it is baked and cured at 150°C for 1 hour. Other details are as described in Example 1.

[0066] Comparative Example 1: The difference is that isocyanate is not added and baking curing is not performed; otherwise, refer to Example 1.

[0067] Comparative Example 2: The difference lies in the following: the high-speed dispersion time in the sand mill is 1 hour, the minimum filtration accuracy is 1μm, and the solid particles in the digital inkjet ink include larger particles with a particle size Dv50 ranging from 0.5μm to 1μm. For other details, please refer to Example 1.

[0068] Performance testing 1. Ink Testing Methods Ink viscosity: Take 500 mL of ink sample, let it stand in the dark for 24 h, and use a Brookfield DV2T / RV rotational viscometer at 25±0.5℃ for 50~100 s. -1 The shear force was measured.

[0069] The particle size Dv50 of the solid particles was directly measured using a Mastersizer 3000+Lab laser particle size analyzer.

[0070] 2. Ink Testing Methods After Digital Printing Adhesion: Using a standardized tool, an orthogonal grid with a 1mm spacing is drawn on the surface of the ink coating. After removing the coating with tape, the percentage of the area that has peeled off is evaluated. The rating is based on a 0-5 system, corresponding to 5B (best adhesion) to 0B (complete peeling) in the ISO / ASTM standards.

[0071] Hardness: A pencil hardness tester was used, with a load of 750g, in accordance with GB / T 6739-2006.

[0072] Alcohol immersion test: At room temperature, immerse the digitally printed ink sample in ethanol with a purity of ≥52% for 6 hours, cover to prevent evaporation, and observe whether the ink wrinkles, peels off, or changes color.

[0073] Rubber abrasion resistance: A reciprocating friction tester is used with a stroke of 50mm, a load of 200g, a speed of 30-40 times / min, and the set number of friction cycles is 300.

[0074] The variable statistics of the examples and comparative examples, as well as the above performance test results, are shown in Table 1 below.

[0075] Table 1. Performance Comparison of Examples and Comparative Examples The above performance results demonstrate that the digital inkjet printing ink for glass substrates provided in this solution possesses superior physical characteristics. The ink has low viscosity, which facilitates precise droplet formation and ejection. Upon spraying onto the glass surface, it quickly levels and fully wets the substrate, ensuring maximum contact area between the ink and glass. The solid particles primarily consist of pigments; these small particles minimize physical defects and stress concentration points at the ink / glass substrate interface, resulting in a stronger interfacial bond. Regarding chemical selection, the hydroxyl-modified acrylic resin contains acrylate and hydroxyl groups. Under sufficient photoinitiator action, it undergoes UV curing with the active monomers to form a crosslinked network with good toughness and high cohesive strength. The participation of isocyanate in thermosetting further enhances the crosslinking density and network strength. Under high-temperature conditions, it can undergo crosslinking reactions with end-capped isocyanates. Furthermore, the difunctionality means that each molecule has two acrylate double bonds that can participate in curing, providing sufficient crosslinking density to ensure the hardness, toughness, and toughness of the ink film. This helps resist stress caused by temperature changes in the glass substrate, preventing the ink film from cracking and peeling.

[0076] In this solution, the strong adhesion of digital inkjet printing on glass substrates is the result of the synergistic effect of the above features, which enables it to withstand friction, cleaning, hot and cold cycles, and even certain moisture or chemical contact common in glass inkjet printing environments.

[0077] Without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of the different embodiments or examples.

[0078] The above description is only a part or preferred embodiment of the present invention and should not be construed as limiting the scope of protection of the present invention. All equivalent structural transformations made using the content of the present invention specification under the overall concept of the present invention, or direct / indirect applications in other related technical fields, are included within the scope of protection of the present invention.

Claims

1. A digital jettable ink for a glass substrate, characterized in that, The raw materials of the digital inkjet ink include, in parts by weight: 20-40 parts of a modified acrylic resin containing hydroxyl groups, 40-60 parts of active monomers, 5-15 parts of isocyanate, 5-10 parts of photoinitiator, 1-10 parts of pigments, 1-10 parts of auxiliary agents, and the viscosity of the digital inkjet ink at 25℃ is 10-30 mPa·s, and the particle size Dv50 of solid particles in the digital inkjet ink is less than 0.5 μm.

2. The direct-write ink for glass substrates according to claim 1, wherein, The modified acrylic resin containing hydroxyl groups includes difunctional epoxy acrylate containing hydroxyl groups, and the viscosity of the difunctional epoxy acrylate containing hydroxyl groups at 25℃ is 500-3000 mPa·s.

3. The direct-write ink for glass substrates according to claim 1, wherein, The active monomers include monomers containing epoxy and / or hydroxyl groups.

4. The direct-write ink for glass substrates according to claim 3, wherein, The active monomers include at least one of hydroxyethyl acrylate, hydroxyethyl phosphate acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, glycidyl methacrylate, glycidyl acrylate, and glycidyl neodecanoate.

5. The direct-write ink for glass substrates according to claim 1, wherein, The photoinitiator includes at least one of 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide, 2,4,6-trimethylbenzoyl-phenyl ethoxy phosphine oxide, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-hydroxycyclohexyl phenyl ketone, 2-isopropylthioxanthone, (2,4,6-trimethylbenzoyl) phenyl phosphine oxide, and 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone; and / or, the auxiliary agents include at least one of dispersants, defoamers, coupling agents, leveling agents, and polymerization inhibitors.

6. A method of preparing a digital ink for glass substrates according to any one of claims 1 to 5, characterized in that, The method includes the following steps: mixing the active monomers, dispersants, and defoamers to perform first stirring, adding pigments to perform second stirring, obtaining a mixed solution, performing sanding dispersion and first filtration to obtain a color paste; adding the modified acrylic resin containing hydroxyl groups, photoinitiator, isocyanate, leveling agent, coupling agent, and polymerization inhibitor to the color paste, performing third stirring and second filtration to obtain the digital inkjet ink for glass substrates.

7. The method for preparing digital inkjet printing ink for glass substrates according to claim 6, characterized in that, The volume ratio of zirconium sand to the mixed solution in the sanding dispersion is (1-2):1, and the particle size of the zirconium sand is 0.2-0.4 mm; and / or, the first filtration includes sequentially passing through filters with precision of 5 μm, 2 μm, and 0.5 μm, and the second filtration includes passing through a filter with precision of 0.5 μm.

8. The method of claim 7, wherein the inkjet ink for glass substrates is prepared by the steps of: The stirring speed of the first stirring is 300-500 rpm, and the time of the first stirring is 5-10 min; and / or, the stirring speed of the second stirring is 2500-3000 rpm, and the time of the second stirring is 2-4 h; and / or, the stirring speed of the third stirring is 300-500 rpm, and the time of the third stirring is 10-20 min.

9. A method of inkjet printing according to any one of claims 1 to 5 for a digital inkjet printing ink for glass substrates, characterized in that, The inkjet method includes spraying the digital inkjet ink onto a glass substrate and curing, and the curing includes post-curing after ultraviolet curing.

10. The method of claim 9, wherein the inkjet printing method is a method for printing an ink for a glass substrate, characterized by, The UV light curing is performed at 800 mJ / cm 2 ~1600 mJ / cm 2 below; and / or, the temperature of the post-curing is 140-170℃.

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