UV-cured high-brightness silver ink

Abstract

The invention discloses UV (ultraviolet) curing high-brightness silver ink, which is characterized in that the pigment for preparing the UV curing high-brightness silver ink is prepared from the following components in parts by mass: 40 to 60 parts of prepolymer, 15 to 30 parts of diluent, 3 to 5 parts of photoinitiator, 10 to 30 parts of aluminum powder and 0.8 to 2.8 parts of orientation agent, and the orientation agent is oligomeric silsesquioxane. According to the UV-cured high-brightness silver ink, in the ink drying process, on one hand, eight chain-shaped organic functional groups R of POSS molecules are enriched on an ink film-air interface to form a surface layer with low surface energy, and aluminum powder is automatically arranged on the interface in parallel under the action of free energy, so that the particle orientation degree is greatly improved; therefore, after the ink is dried, as the orientation degree of the aluminum powder particles is greatly improved, the mirror reflection degree of light rays is also greatly improved, and the brightness of the ink is further greatly improved.

Description

Technical Field

[0001] This invention relates to the field of ink technology, and in particular to a UV-curable high-gloss silver ink. Background Technology

[0002] Existing silver inks use aluminum powder as the pigment. Due to the large specific surface area and high surface energy of aluminum powder, its compatibility with organic resins is poor, leading to easy agglomeration after formulation. Furthermore, aluminum powder itself has poor orientation, easily sliding and tumbling during ink film drying. These factors result in poor aluminum powder orientation after drying, with light reflection primarily being diffuse. This leads to problems such as dull color and insufficient brightness in the silver ink process, further affecting the enhancement of packaging quality.

[0003] Therefore, it is necessary to provide a UV-curable high-gloss silver ink to solve the above problems. Summary of the Invention

[0004] A UV-curable high-gloss silver ink, wherein the raw materials for preparing the UV-curable high-gloss silver ink, by weight, include:

[0005] 40 to 60 parts of prepolymer;

[0006] 15 to 30 parts diluent;

[0007] 3 to 5 parts of photoinitiator;

[0008] 10 to 30 parts aluminum powder; and

[0009] Orientation agent: 0.8 to 2.8 parts;

[0010] The orientation agent is an oligomeric silsesquioxane.

[0011] In one embodiment, the prepolymer is selected from at least one of aliphatic polyurethane acrylate resin, aromatic polyurethane acrylate resin, modified polyurethane acrylate resin, epoxy acrylate resin, epoxy methacrylate resin, modified epoxy acrylate resin, phenolic epoxy acrylate resin, polyester acrylate resin, modified polyester acrylate resin, and hyperbranched polyester acrylate resin.

[0012] In one embodiment, the diluent is selected from any one of 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, dipropylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated neopentyl glycol diacrylate, 2-phenoxyethyl acrylate, tetrahydrofuran methacrylate, pentaerythritol tetraacrylate, isobornyl acrylate, and lauryl acrylate.

[0013] In one embodiment, the photoinitiator is a pyrolysis photoinitiator or a hydrogen abstraction photoinitiator.

[0014] In one embodiment, the pyrolytic photoinitiator is selected from any one of ethyl 4-dimethylaminobenzoate, 1-hydroxy-cyclohexyl-phenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and benzoin dimethyl ether.

[0015] In one embodiment, the aluminum powder has a particle size of 10 nm to 15 nm.

[0016] In one embodiment, the orientation agent is selected from at least one of methacryloyloxypropyl cage polysilsesquioxane, glycidyl cage polysilsesquioxane, hydroxylated isobutyl cage polysilsesquioxane, perfluoroalkyl cage polysilsesquioxane, and aminopropyl cage polysilsesquioxane.

[0017] In one embodiment, the orientation agent is present in a mass fraction of 1.3 to 2.3 parts.

[0018] In one embodiment, at least one chain-like organic functional group R of the orienting agent molecule is −(CH2)3-NH-CH2-CH2-DEAEMA.

[0019] In one embodiment, of the eight chain-like organic functional groups R of the orienting agent molecule, two are −(CH2)3-NH-CH2-CH2-DEAEMA, and the remaining six are methacryloyloxypropyl.

[0020] The aforementioned UV-curable high-gloss silver ink contains an orientation agent, oligomeric silsesquioxane (POSS). POSS molecules have a cage-like inorganic core and eight chain-like organic functional groups R connected to it. During ink drying, firstly, the eight chain-like organic functional groups R of the POSS molecule accumulate at the ink-air interface, forming a low surface energy layer. Under the influence of free energy, aluminum powder will automatically align in parallel at this interface, significantly improving particle orientation. Secondly, the cage-like inorganic core located between the aluminum powder particles acts as a support in the ink layer, preventing the aluminum powder particles from flipping. Thirdly, when the chain-like organic functional group R of the POSS molecule is methacrylate or epoxy group, this functional group can also polymerize with the prepolymer during the UV curing stage, thoroughly fixing the aluminum powder particles while significantly improving the ink's abrasion resistance. Therefore, after ink drying, the significantly improved orientation of the aluminum powder particles leads to a significantly increased degree of specular reflection of light, thereby greatly enhancing the ink's gloss. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the POSS molecule. Detailed Implementation

[0022] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0023] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is considered to be "connected" or "connected" to another element, it can be directly connected to the other element or there may be an intervening element. The terms "upper," "lower," "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0024] The following section provides a more detailed description of UV-cured high-gloss silver ink, in conjunction with the accompanying drawings and specific embodiments.

[0025] One embodiment of the UV-curable high-gloss silver ink, by weight, comprises the following raw materials: 40 to 60 parts of prepolymer, 15 to 30 parts of diluent, 3 to 5 parts of photoinitiator, 10 to 30 parts of aluminum powder, and 0.8 to 2.8 parts of POSS orientation agent.

[0026] The prepolymer, with a mass fraction of 40 to 60 parts, acts as a film-forming substance. Under photoinitiator and ultraviolet irradiation, it can cross-link and polymerize with diluent to form a three-dimensional network structure, thereby enabling UV-curable high-gloss silver ink to cure rapidly.

[0027] Optionally, the prepolymer includes, but is not limited to: aliphatic polyurethane acrylate resin, aromatic polyurethane acrylate resin, modified polyurethane acrylate resin, epoxy acrylate resin, epoxy methacrylate resin, modified epoxy acrylate resin, phenolic epoxy acrylate resin, polyester acrylate resin, modified polyester acrylate resin, and hyperbranched polyester acrylate resin.

[0028] The thinner, in parts by weight of 15 to 30, acts as both a solvent and a reactant in the UV ink system. On one hand, the thinner can dilute high-viscosity prepolymers, making the ink meet printability requirements. On the other hand, under the action of ultraviolet light and photoinitiators, the thinner can undergo cross-linking polymerization with the prepolymer, thereby enabling the ink to cure rapidly.

[0029] Optionally, the diluent includes, but is not limited to: 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated neopentyl glycol diacrylate, 2-phenoxyethyl acrylate, tetrahydrofuran methacrylate, pentaerythritol tetraacrylate, isobornyl acrylate, and lauryl acrylate.

[0030] The photoinitiator, in parts by weight of 3 to 5, plays a role in absorbing ultraviolet light and generating active free radicals or cations in the UV ink system, thereby triggering the cross-linking and curing of the prepolymer and diluent.

[0031] In this embodiment, the photoinitiator includes a pyrolysis-type photoinitiator and a hydrogen abstraction-type photoinitiator.

[0032] Optionally, the pyrolysis photoinitiator includes, but is not limited to: ethyl 4-dimethylaminobenzoate, 1-hydroxy-cyclohexyl-phenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, benzoin dimethyl ether, etc.

[0033] Optionally, hydrogen-abstracting photoinitiators include, but are not limited to: ethyl 4-dimethylaminobenzoate, isooctyl p-dimethylaminobenzoate, isopropylthioxanthone, benzophenone, etc.

[0034] Aluminum powder, in parts by weight of 10 to 30, is used as a raw material for UV-cured high-gloss silver ink, giving the ink a silver color.

[0035] In this embodiment, the particle size of the aluminum powder is 10nm~15nm. By limiting the particle size of the aluminum powder, it can be ensured that the UV-cured high-gloss silver ink has good printability while having high brightness.

[0036] The orientation agent, in parts by weight of 0.8 to 2.8, can orient the aluminum powder during the drying process of UV-cured high-gloss silver ink.

[0037] Specifically, the orientation agent is oligomeric silsesquioxane (POSS), please refer to [link / reference needed]. Figure 1The POSS molecule possesses a cage-like inorganic core and eight chain-like organic functional groups R. The cage-like inorganic core consists of eight alternating Si atoms and twelve O atoms, forming a cubic octahedral cage (T8 cage) with a diameter of approximately 1.5 nm–2.0 nm. Each Si vertex is further connected to a chain-like organic functional group R, forming eight "tentacles" extending into space. The chain-like organic functional groups R can be inert alkyl groups or reactive functional groups (such as epoxy, amino, methacrylate, hydroxyl, etc.). The entire molecule exhibits a "hard core, soft shell" nanoscale cage-like spherical structure with a density of 0.9–1.3 g / cm³; it is soluble in esters, ketones, and aromatic hydrocarbons, and is compatible with ink resins without crystallization.

[0038] The unique structure of POSS molecules allows them to produce the following beneficial effects during the printing and drying process of UV inks:

[0039] (1) The eight low-polarity chain-like organic functional groups R of the POSS molecule will be enriched at the ink film-air interface to form a low surface energy surface layer with a thickness of about 2 nm. Under the action of free energy, the aluminum sheet will spontaneously spread parallel at the interface, that is, the special surface energy gradient allows the aluminum powder to achieve spontaneous orientation.

[0040] (2) The rigid cage-like inorganic core of the POSS molecule will be inserted between the aluminum powders to act as a support, thereby preventing the aluminum powders from flipping due to the movement of ink molecules.

[0041] (3) When the chain organic functional group R is methacrylate or epoxy group, POSS molecules can also act as prepolymers and cross-link with diluents during the UV curing stage, which can significantly improve the abrasion resistance of ink while completely locking aluminum powder particles.

[0042] (4) The refractive index of the POSS cage-type inorganic core is 1.45-1.55, which is between the refractive index of polymer resin and aluminum sheet. It can reduce the refractive index difference at the medium-aluminum interface on a macroscopic level and reduce diffuse reflection. The nanocage-type inorganic core has virtually no scattering of visible light and will not weaken the metallic luster of aluminum powder. On the contrary, it will enhance the optical gain effect of specular reflection peak intensity due to the improved surface flatness.

[0043] Optionally, POSS includes, but is not limited to, at least one of: methacryloxypropyl cage polysilsesquioxane (MA-POSS), glycidyl cage polysilsesquioxane (EP-POSS), hydroxylated isobutyl cage polysilsesquioxane (iBu-POSS-OH), perfluoroalkyl cage polysilsesquioxane (Fluoro-POSS), and aminopropyl cage polysilsesquioxane (Amino-POSS).

[0044] Preferably, at least one chain-like organic functional group R of the POSS molecule is −(CH2)3-NH-CH2-CH2-DEAEMA (DEAEMA: diethylaminoethyl methacrylate homopolymer segment, tertiary amine side chain). Since the glass transition temperature (Tg) of this chain-like organic functional group R is 32°C, it exhibits a "soft segment" in the ink film. After the ink dries, the ink layer temperature can be raised above the glass transition temperature by friction or heating. At this point, the DEAEMA segment enters a rubbery state, the chain segment movement accelerates, and the position of the aluminum powder changes slightly. This slight change causes a change in the reflected light on the aluminum powder surface, which can appear as a dynamic metallic flash in the human eye. After heating is stopped, the temperature drops, and the process of temperature drop again produces a dynamic metallic flash in the human eye until the chain segment refreezes, the aluminum powder returns to its original position, and the ink layer returns to its high-gloss state.

[0045] Preferably, among the eight chain-like organic functional groups R of the POSS molecule, two are −(CH2)3-NH-CH2-CH2-DEAEMA and the remaining six are methacryloyloxypropyl. During the UV curing process, a bifunctional structure of "crosslinking region + dynamic soft segment" can be formed, so that the curing process can still exhibit a strong thermally triggered reversible flash.

[0046] Preferably, the mass fraction of the orientation agent is 1.3 to 2.3 parts. Experiments have shown that when the mass fraction of the orientation agent is 0.8 to 1.3 parts, the orientation degree of the aluminum powder increases with the increase of the orientation agent; when the mass fraction of the orientation agent is 1.3 to 2.3 parts, the orientation degree of the aluminum powder is at its peak; when the mass fraction of the orientation agent is greater than 2.3 parts, the orientation degree of the aluminum powder decreases significantly with the increase of the orientation agent. In addition, excessive POSS will cause the ink film to become brittle due to excessive cross-linking of the rigid cage.

[0047] The aforementioned UV-curable high-gloss silver ink contains an orientation agent, oligomeric silsesquioxane (POSS). POSS molecules have a cage-like inorganic core and eight chain-like organic functional groups R connected to it. During ink drying, firstly, the eight chain-like organic functional groups R of the POSS molecule accumulate at the ink-air interface, forming a low surface energy layer. Under the influence of free energy, aluminum powder will automatically align in parallel at this interface, significantly improving particle orientation. Secondly, the cage-like inorganic core located between the aluminum powder particles acts as a support in the ink layer, preventing the aluminum powder particles from flipping. Thirdly, when the chain-like organic functional group R of the POSS molecule is methacrylate or epoxy group, this functional group can also polymerize with the prepolymer during the UV curing stage, thoroughly fixing the aluminum powder particles while significantly improving the ink's abrasion resistance. Therefore, after ink drying, the significantly improved orientation of the aluminum powder particles leads to a significantly increased degree of specular reflection of light, thereby greatly enhancing the ink's gloss.

[0048] The following are specific examples.

[0049] Example 1

[0050] Please see Figure 1 This embodiment provides a UV-curable high-gloss silver ink. By weight, the raw materials of the UV-curable high-gloss silver ink include: 40 parts of prepolymer, 15 parts of diluent, 3 parts of photoinitiator, 10 parts of aluminum powder, and 0.8 parts of POSS orientation agent.

[0051] In this embodiment, the prepolymer is a modified polyurethane acrylate resin, model RJ4257, provided by Guangdong Gaoliang Technology Co., Ltd.; the diluent is lauryl acrylate, model 2101, provided by Guangzhou Lihou Trading Co., Ltd.; the photoinitiator is ethyl 4-dimethylaminobenzoate, provided by Shanghai Lianzhi Chemical Co., Ltd.; and the orientation agent is methacryloxypropyl cage-type polysilsesquioxane (MA-POSS), provided by Guangzhou Yixin Technology Co., Ltd.

[0052] The aforementioned UV-curable high-gloss silver ink contains an orientation agent, oligomeric silsesquioxane (POSS). POSS molecules have a cage-like inorganic core and eight chain-like organic functional groups R connected to it. During ink drying, firstly, the eight chain-like organic functional groups R of the POSS molecule accumulate at the ink-air interface, forming a low surface energy layer. Under the influence of free energy, aluminum powder will automatically align in parallel at this interface, significantly improving particle orientation. Secondly, the cage-like inorganic core located between the aluminum powder particles acts as a support in the ink layer, preventing the aluminum powder particles from flipping. Thirdly, when the chain-like organic functional group R of the POSS molecule is methacrylate or epoxy group, this functional group can also polymerize with the prepolymer during the UV curing stage, thoroughly fixing the aluminum powder particles while significantly improving the ink's abrasion resistance. Therefore, after ink drying, the significantly improved orientation of the aluminum powder particles leads to a significantly increased degree of specular reflection of light, thereby greatly enhancing the ink's gloss.

[0053] Examples 2-5 and Comparative Examples

[0054] The UV-curable high-gloss silver inks of Comparative Examples 1-5 have similar compositions to those of Examples 1-5, except that no orientation agent was added. See the table below for details.

[0055] Table 1 Raw material information for each embodiment

[0056]

[0057] Table 2 Raw material information for each comparative example

[0058]

[0059] Effect test

[0060] The orientation and gloss of the UV-cured high-gloss silver inks of Examples 1-5 and the comparative examples were tested using a two-dimensional wide-angle X-ray diffractometer and a gloss meter. The test results are shown in the table below.

[0061] Table 3 Orientation and gloss of each embodiment and comparative example

[0062]

[0063] Note: 1. Orientation degree is expressed as the ratio of peak intensity of aluminum powder (111) / (200) in two-dimensional wide-angle XRD I(111) / I(200); the larger the ratio, the better the "flat" orientation of aluminum powder.

[0064] 2. Increase = (Example value / Comparative value - 1) * 100%.

[0065] As shown in Table 3, after printing, the UV-cured high-gloss silver inks of Examples 2-4 showed an increase of more than 35% in the orientation of aluminum powder and the gloss of the silver ink process, with a significant increase ratio.

[0066] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A UV-curable high-gloss silver ink, characterized in that, The raw materials for preparing the UV-curable high-gloss silver ink, by weight, include: 40 to 60 parts of prepolymer; 15 to 30 parts diluent; 3 to 5 parts of photoinitiator; 10 to 30 parts aluminum powder; and Orientation agent: 0.8 to 2.8 parts; The orientation agent is an oligomeric silsesquioxane.

2. The UV-curable high-gloss silver ink according to claim 1, characterized in that, The prepolymer is selected from at least one of aliphatic polyurethane acrylate resin, aromatic polyurethane acrylate resin, modified polyurethane acrylate resin, epoxy acrylate resin, epoxy methacrylate resin, modified epoxy acrylate resin, phenolic epoxy acrylate resin, polyester acrylate resin, modified polyester acrylate resin, and hyperbranched polyester acrylate resin.

3. The UV-curable high-gloss silver ink according to claim 2, characterized in that, The diluent is selected from any one of 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, dipropylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated neopentyl glycol diacrylate, 2-phenoxyethyl acrylate, tetrahydrofuran methacrylate, pentaerythritol tetraacrylate, isobornyl acrylate, and lauryl acrylate.

4. The UV-curable high-gloss silver ink according to claim 3, characterized in that, The photoinitiator is a pyrolysis-type photoinitiator or a hydrogen abstraction-type photoinitiator.

5. The UV-curable high-gloss silver ink according to claim 4, characterized in that, The pyrolytic photoinitiator is selected from any one of ethyl 4-dimethylaminobenzoate, 1-hydroxy-cyclohexyl-phenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and benzoin dimethyl ether.

6. The UV-curable high-gloss silver ink according to claim 1, characterized in that, The aluminum powder has a particle size of 10nm~15nm.

7. The UV-curable high-gloss silver ink according to claim 1, characterized in that, The orientation agent is selected from at least one of methacryloxypropyl cage polysilsesquioxane, glycidyl cage polysilsesquioxane, hydroxylated isobutyl cage polysilsesquioxane, perfluoroalkyl cage polysilsesquioxane, and aminopropyl cage polysilsesquioxane.

8. The UV-curable high-gloss silver ink according to claim 7, characterized in that, The proportion of the orienting agent is 1.3 to 2.3 parts by mass.

9. The UV-curable high-gloss silver ink according to claim 8, characterized in that, At least one chain-like organic functional group R of the directional agent molecule is −(CH2)3-NH-CH2-CH2-DEAEMA.

10. The UV-curable high-gloss silver ink according to claim 9, characterized in that, Of the eight chain-like organic functional groups R in the directional agent molecule, two are −(CH2)3-NH-CH2-CH2-DEAEMA, and the remaining six are methacryloyloxypropyl.

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