A decorative ink for glass cover plates, its preparation method and applications

Abstract

The present invention discloses a decorative ink for a glass cover plate, a preparation method thereof and an application. The ink comprises component A; component A includes raw materials: a resin composition, an auxiliary agent and a solvent. The resin composition includes a polyurethane-modified epoxy resin, a silicone resin and a polycarbonate diol resin. Among them, the silicone resin contains an amino group. The weight ratio of the polyurethane-modified epoxy resin, the silicone resin and the polycarbonate diol resin in the resin composition is 1-5:1-5:1-5. After the ink of this solution is dispensed and cured under ultra-low temperature conditions (-88 °C), the shear force / area ratio (F / S value) thereof breaks through 1.4 and there is no phenomenon of glue layer peeling off. This ink always maintains excellent interfacial adhesion within a wide temperature range, effectively solves the industry problems of insufficient shear strength and embrittlement and peeling off of the glue layer of traditional inks in extremely low temperature environments, and fills the material blank of inks with ultra-low temperature shear performance for application equipment in alpine regions.

Description

Technical Field

[0001] The present invention relates to the technical field of inks, and particularly to a decorative ink for glass covers, a preparation method thereof, and an application thereof. Background Art

[0002] With the accelerating iteration of the consumer electronics industry towards high precision, lightweight, and environmental adaptability, the decorative ink coating for glass covers is facing the need for coordinated improvement of multi-dimensional performance indicators. In the field of precision devices such as mobile phones and smart watches, the transition of the substrate from traditional organic films to glass has triggered a paradigm shift in interfacial bonding characteristics: the surface energy of the organic substrate is relatively low, and good adhesion can be achieved through physical anchoring; while the high surface energy characteristics of the glass substrate require the ink system to simultaneously meet the dual requirements of dynamic flexibility and rigid anchoring, which poses a more complex structure-activity relationship challenge to the molecular design of the coating material. Especially under extreme low-temperature conditions (such as -88°C environment), the brittle phase transformation of materials and the thermal stress mismatch phenomenon are significantly exacerbated, requiring the coating to simultaneously achieve the coordinated optimization of the anti-brittle fracture threshold and the mechanical stress buffering ability to ensure the structural integrity and aesthetic performance stability of the device in cold climate scenarios and low-temperature tests.

[0003] Currently, epoxy resin, polyurethane, or acrylic resin systems are generally used in the industry as ink bases, and high adhesion at room temperature (the F / S ratio in the pull-out force test is usually 1.0 - 1.3) and high wear resistance are achieved by adding curing agents, pigments, and additives. However, such traditional inks exhibit significant defects under ultra-low temperature conditions: firstly, the interfacial bonding strength between the resin matrix and glass drops sharply at ultra-low temperatures, resulting in brittle fracture of the coating; secondly, the difference in the thermal expansion coefficients of the ink and substrates such as glass and metal is amplified at low temperatures, leading to stress concentration, and ultimately causing the coating to peel off from the substrate surface (the pull-out force F / S value often falls below the industry safety threshold of 1.4). Such failure phenomena are particularly prominent in key parts such as the glass covers and metal middle frames of mobile phones and smart wearable devices, directly affecting the reliability and service life of the products.

[0004] In the prior art, although attempts have been made to improve the flexibility of the ink by plasticizer modification or introducing elastomer components to reduce the incidence of the coating peeling off from the substrate surface, such solutions often come at the cost of coating hardness, and the method of simply increasing the crosslinking density to enhance adhesion instead exacerbates the low-temperature embrittlement tendency, forming a performance contradiction.

[0005] Therefore, there is an urgent need to develop a new type of ink system that can maintain stable high adhesion, and at the same time has a high pull-out force and is not easily detached even at ultra-low temperatures. Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art. For this purpose, the present invention provides a decorative ink for glass cover plates, and this ink system has stable high adhesion, especially high pull-out force and is not easy to fall off even at ultra-low temperatures.

[0007] The present invention also provides a preparation method for the above ink.

[0008] The present invention also provides an application of the above ink.

[0009] According to one aspect of the present invention, a decorative ink for glass cover plates is provided, including component A; component A includes raw materials in the following weight parts: 15-45 parts of a resin composition, 30-50 parts of a pigment, 3-8 parts of a filler, 3-8 parts of a curing agent, 5.5-12.5 parts of an auxiliary agent, and 6-22 parts of a solvent. The resin composition includes a polyurethane-modified epoxy resin, a silicone resin, and a polycarbonate diol resin (PCD). Among them, the silicone resin contains an amino group, and the weight ratio of the polyurethane-modified epoxy resin, the silicone resin, and the polycarbonate diol resin in the resin composition is 1-5:1-5:1-5.

[0010] The ink according to the embodiment of the present invention has at least the following beneficial effects: The present invention adopts an ink formula in which three resins are combined synergistically in a specific ratio. By optimizing the interfacial compatibility and the molecular chain segment movement ability between the resins, the wetting and dispersion effect of the resin on the powder material is significantly enhanced, thereby constructing a uniform and dense paint film structure. After the ink of the present invention is dispensed and cured under ultra-low temperature conditions (-88°C), its shear force / area ratio (F / S value) breaks through 1.4 and there is no phenomenon of glue layer peeling off. At the same time, this ink always maintains excellent interfacial adhesion, effectively solving the industry problems of insufficient shear strength and embrittlement and peeling of the glue layer of traditional low-temperature inks in extremely low-temperature environments. Especially for terminal devices using 8540 series adhesives for cover plate bonding, the solution of the present invention can significantly improve their structural reliability under ultra-low temperature working conditions, filling the material gap of inks with ultra-low temperature shear performance for equipment applications in alpine regions, and providing an innovative solution for bonding schemes in extreme temperature environments. Compared with the prior art, the ink system of the present invention has the following technical advantages:

[0011] 1) Extended processing window characteristics: Adopting the solution formula, the ink has a long activation period, which can better ensure the process stability of continuous printing operations.

[0012] 2) High hiding optical performance: When the ink of the present invention is applied, the optical density (OD value) is high, and the hiding effect is significantly improved compared with the traditional formula.

[0013] 3) Printing suitability of single-component system: Excellent leveling property can be achieved without compounding, with good printing effect, high consistency in continuous printing appearance, and can effectively meet the requirements of high-precision graphic reproduction.

[0014] 4) Multi-dimensional environmental tolerance: It has excellent chemical stability. At the same time, it also has good extreme temperature mechanical properties: it has high shear force and is not easy to fall off at ultra-low temperature, and can still maintain high adhesion after thermal shock cycling.

[0015] According to some embodiments of the present invention, the weight ratio of the polyurethane-modified epoxy resin, silicone resin and polycarbonate diol resin in the resin composition is 1-3:1-3:1-3.

[0016] According to some embodiments of the present invention, the polyurethane-modified epoxy resin has at least one of the following characteristics:

[0017] 1) The glass transition temperature is 120-130 °C;

[0018] 2) The epoxy equivalent is 170-250 g / eq.

[0019] According to some embodiments of the present invention, the polyurethane-modified epoxy resin has at least one of the following characteristics:

[0020] 1) The glass transition temperature is 120-130 °C;

[0021] 2) The epoxy equivalent is 195-220 g / eq;

[0022] 3) The viscosity is 10000-16000 mPa·s (25 °C).

[0023] According to some embodiments of the present invention, the polyurethane-modified epoxy resin has at least one of the following characteristics:

[0024] 1) The glass transition temperature is 120-130 °C;

[0025] 2) The epoxy equivalent is 195-240 g / eq;

[0026] 3) The viscosity is 10000-16000 mPa·s (25 °C).

[0027] According to some embodiments of the present invention, the polyurethane-modified epoxy resin includes NPER-133L produced by South Asia Company or HyPox UA10 produced by CVC Thermoset Specialties.

[0028] According to some embodiments of the present invention, the silicone resin has at least one of the following characteristics:

[0029] 1) Amine equivalent: 250 - 270 g / NH;

[0030] 2) Solids content ≥ 97%;

[0031] 3) Kinematic viscosity is between 3500 ± 1000 cSt.

[0032] According to some embodiments of the present invention, the silicone resin includes DOWSIL™ 3055 from Dow.

[0033] According to some embodiments of the present invention, the polycarbonate diol resin has at least one of the following characteristics:

[0034] 1) Hydroxyl value is between 50 - 65 KOH / g;

[0035] 2) Solids content ≥ 97%;

[0036] 3) Pencil hardness after curing < F, test condition: 300 g force.

[0037] According to some embodiments of the present invention, the polycarbonate diol resin has at least one of the following characteristics:

[0038] 1) Hydroxyl value is between 50 - 60 KOH / g;

[0039] 2) Solids content ≥ 97%;

[0040] 3) Pencil hardness after curing < F, test condition: 300 g force.

[0041] The flexibility of the paint film under ultra - low temperature conditions is effectively improved by adding polycarbonate diol resins such as T5652.

[0042] According to some embodiments of the present invention, the polycarbonate diol resin includes T5652 polycarbonate diol resin produced by Asahi Kasei Corporation.

[0043] According to some embodiments of the present invention, the mass proportion of the resin composition in the raw materials of component A is 15 - 45%.

[0044] According to some embodiments of the present invention, component A includes the following raw materials in parts by weight: 15 - 45 parts of resin composition, 41.5 - 78.5 parts of additives, and 6 - 22 parts of solvent.

[0045] According to some embodiments of the present invention, the additive includes a curing agent, and the curing agent includes blocked isocyanate. By adding blocked isocyanate, the activation period is effectively increased, and the appearance effect of the ink during printing will not be affected by the curing degree. The curing reaction of polyurethane-modified epoxy resin and silicone resin provides the main structure. Since the activity of polyurethane-modified epoxy and the activity of amine value-modified silicone resin do not react at room temperature and react rapidly at 150°C, by using a hydroxyl value-containing polycarbonate diol resin and a blocked isocyanate curing agent (such as DESMODUR BL 3175A), it is also possible to achieve non-reaction at room temperature and rapid reaction at 150°C to adjust the activation period and achieve the balance of "long activation period and rapid curing".

[0046] According to some embodiments of the present invention, the curing agent includes at least one of DESMODUR BL 3175A produced by Covestro, SBN-70D of Asahi Kasei, or DB-85121 with double bonds.

[0047] According to some embodiments of the present invention, the curing agent includes DESMODUR BL 3175A produced by Covestro. DESMODUR BL 3175A is a blocked HDI curing agent.

[0048] According to some embodiments of the present invention, the mass ratio of the curing agent in the raw materials of component A is 3-8%.

[0049] According to some embodiments of the present invention, the additive includes pigments and fillers.

[0050] According to some embodiments of the present invention, the pigment includes white pigments.

[0051] According to some embodiments of the present invention, the pigment includes at least one of titanium dioxide, zinc white, or lithopone. It can also be other white pigments (such as lead white, antimony white, or other organic white pigments, etc.), or other color pigments can be selected according to needs.

[0052] According to some embodiments of the present invention, the median particle size of the pigment is below 0.25 μm. By controlling the median particle size of the pigment within this range, the high requirements for the optical density (OD value) of high-whiteness products can be more effectively met. When the median particle size is above 0.3 μm, the OD value is below 2, which can meet the requirements of ordinary products.

[0053] According to some embodiments of the present invention, the median particle size of the pigment is between 0.15 and 0.22 μm.

[0054] According to some embodiments of the present invention, the median particle size of the pigment is between 0.18 and 0.2 μm.

[0055] According to some embodiments of the present invention, the median particle size of the pigment is between 0.19 ± 0.002 μm.

[0056] When the median particle size is within this level range, it can better ensure the OD value of the ink layer and can also better ensure the hiding power.

[0057] According to some embodiments of the present invention, the filler includes at least one of barium sulfate, calcium carbonate, talcum powder, kaolin, or mica powder.

[0058] According to some embodiments of the present invention, the particle size of the filler is at the nanoscale.

[0059] Using ultrafine pigments and synchronously adding nanoscale fillers can effectively fill between the nanoscale fillers, reduce the voids between the powder materials in the paint film, form a dense paint film, and can synergistically improve the OD value of the ink layer.

[0060] According to some embodiments of the present invention, the sum of the masses of the pigment and the filler accounts for 33 - 58% by mass in the raw materials of component A.

[0061] According to some embodiments of the present invention, the mass ratio of the pigment in the raw materials of component A is 30 - 50%.

[0062] According to some embodiments of the present invention, the mass ratio of the filler in the raw materials of component A is 3 - 8%.

[0063] According to some embodiments of the present invention, the solvent includes at least one of ester solvents and ketone solvents.

[0064] According to some embodiments of the present invention, the ester solvents include at least one of PMA (propylene glycol methyl ether acetate), ethyl acetate, butyl acetate, dimethyl carbonate (DMC), diethyl carbonate, dibutyl carbonate, diisopropyl carbonate, or dibasic acid ester (DBE).

[0065] According to some embodiments of the present invention, the ketone solvents include at least one of methyl isobutyl ketone and isophorone.

[0066] According to some embodiments of the present invention, the solvent includes at least one of PMA (propylene glycol methyl ether acetate), DBE (dibasic acid ester), and isophorone.

[0067] According to some embodiments of the present invention, the additives include at least one of dispersants, defoamers, rheology additives, and leveling agents.

[0068] According to some embodiments of the present invention, the additives include dispersants, defoamers, rheology additives, and leveling agents.

[0069] According to some embodiments of the present invention, the auxiliary agent comprises raw materials in the following parts by weight: 4 to 8 parts of a dispersant, 0.5 to 2 parts of an antifoaming agent, 0.5 to 1.5 parts of a rheological aid, and 0.5 to 1 part of a leveling agent. One part in the parts by weight of this auxiliary agent is equal to the amount represented by one part of other raw materials in Component A.

[0070] According to some embodiments of the present invention, the dispersant comprises at least one of BYK 161, BYK 110, BYK 163 produced by BYK Chemie, or TEGO 710 produced by Evonik Industries AG.

[0071] According to some embodiments of the present invention, the dispersant comprises BYK 161 produced by BYK Chemie. BYK 161 is a high molecular weight auxiliary agent of BYK company, which deflocculates pigments through steric hindrance; this dispersant has an efficient dispersing effect on pigments and has no influence on the adhesion of the paint film to glass.

[0072] According to some embodiments of the present invention, the antifoaming agent comprises at least one of BYK 011, BYK 052, or BYK 066N produced by BYK Chemie.

[0073] According to some embodiments of the present invention, the antifoaming agent comprises BYK 011 produced by BYK Chemie. The antifoaming agent BYK 011 is a silicon-free powerful antifoaming agent that can effectively improve the problem of air bubbles in the paint film during the printing process.

[0074] According to some embodiments of the present invention, the rheological aid is at least one of polyamide wax HPA 202 or organobentonite.

[0075] According to some embodiments of the present invention, the rheological aid is Claytone APA bentonite produced by Lockwood Corporation of the United States. The addition of bentonite effectively improves the grinding efficiency, enabling this nano-barium sulfate BF-20 to be easily dispersed to ≤10 μm.

[0076] According to some embodiments of the present invention, the leveling agent comprises a polyether-modified silicone-based leveling agent.

[0077] According to some embodiments of the present invention, the leveling agent comprises BYK 333 produced by BYK Chemie. BYK 333 is a leveling agent of the polyether-modified polydimethylsiloxane solution type that can effectively improve the paint film, strongly reduce the surface tension; it has excellent substrate wetting ability, prevents cratering, and increases surface smoothness.

[0078] According to some embodiments of the present invention, the ink further comprises Component B, which includes a coupling agent.

[0079] According to some embodiments of the present invention, the mass ratio of component B to component A is 2 to 4:100.

[0080] According to some embodiments of the present invention, the coupling agent is a silane coupling agent.

[0081] According to some embodiments of the present invention, the coupling agent includes at least one of glycidyl alkyltrialkoxysilane, 3,4-cyclohexyl epoxy alkyltrialkoxysilane, aminosiloxane, Dow Corning coupling agents Z-6040, Z-6030, Z-6020, and Z-6011.

[0082] According to some embodiments of the present invention, the coupling agent is an epoxy group silane coupling agent.

[0083] According to some embodiments of the present invention, the coupling agent includes Dow Corning coupling agent Z-6040.

[0084] According to some embodiments of the present invention, the ink further includes component C, and component C includes a diluent.

[0085] According to some embodiments of the present invention, the diluent includes at least one of 200# solvent oil produced by Hubei Taihechang Chemical Industry, alcohol ether diluents, aliphatic hydrocarbons, xylene, n-butanol, or US-2 solvent produced by Sherwin-Williams.

[0086] According to some embodiments of the present invention, the diluent includes 200# solvent oil. The 200# solvent oil is super slow-drying and non-polar. Using this diluent can make the ink viscosity more stable. At the same time, this diluent has a low odor and is easily acceptable to production employees.

[0087] According to some embodiments of the present invention, the mass ratio of component C to component A is 5 to 15:100.

[0088] According to some embodiments of the present invention, the ink comprises 100 parts by weight of component A, 2 to 4 parts by weight of component B, and 5 to 15 parts by weight of component C; wherein, the additives include a dispersant, an antifoaming agent, a rheology aid, and a leveling agent, and component A comprises raw materials in the following parts by weight: 15 to 45 parts of a resin composition, 30 to 50 parts of a pigment, 3 to 8 parts of a filler, 3 to 8 parts of a curing agent, 4 to 8 parts of a dispersant, 0.5 to 2 parts of an antifoaming agent, 0.5 to 1.5 parts of a rheology aid, 0.5 to 1 part of a leveling agent, and 6 to 22 parts of a solvent. The resin composition comprises a polyurethane-modified epoxy resin, a silicone resin, and a polycarbonate diol resin; the pigment comprises a white pigment; the dispersant comprises BYK 161; the antifoaming agent comprises BYK 011; the rheology aid comprises Claytone APA bentonite; the leveling agent comprises BYK 333; component B comprises a coupling agent; component C comprises a diluent, and the diluent comprises 200# solvent oil.

[0089] The ink of the present invention's solution constructs a high-performance ink system through the synergistic effect of multiple components. By the synergistic compatibility of a polyurethane-modified epoxy resin, a silicone resin, and a polycarbonate diol resin, the adhesion performance of the ink is significantly improved; introducing a polycarbonate diol resin (PCD) as a flexible chain segment regulator significantly improves the flexibility of the paint film under ultra-low temperature conditions, effectively avoiding cracking at low temperatures; through the synergistic cooperation of the resin composition and the powder particle size, the OD value is significantly increased; at the same time, a blocked isocyanate curing agent is used to maintain a stable single-component state at room temperature, and the activation period is extended to more than 24 hours. This system avoids premature crosslinking of the prepolymer during the printing process, ensuring the decoupled control of the ink leveling property and the final curing degree, and avoiding the influence of the curing degree on the appearance effect of the ink during the printing process; in addition, by adopting a synergistic system of an organosilicon leveling agent and a silicone-free antifoaming agent, problems such as oil separation and bubbles occurring during the printing process of the paint film are effectively improved, enabling the paint film to be more evenly distributed on the surface of the substrate; adopting an environmentally friendly diluent system - 200# solvent oil subjected to deep hydrotreatment can not only effectively stabilize the ink viscosity but also significantly reduce the VOC emissions compared with the traditional system, meeting the requirements of environmentally friendly production; with the low odor characteristic, the acceptance by employees is higher, which is beneficial to improving production efficiency.

[0090] According to another aspect of the present invention, a preparation method of the decorative ink for the above glass cover plate is provided. The additives include a dispersant, an antifoaming agent, a rheology aid, and a leveling agent, and the solvent includes an ester solvent and a ketone solvent;

[0091] The preparation method comprises the following steps:

[0092] S1. Mix the polyurethane-modified epoxy resin with the ester solvent to obtain mixture I;

[0093] S2. Add silicone resin, polycarbonate diol resin, dispersant, pigment, filler and rheological aid to the mixture I to obtain mixture II;

[0094] S3. Add curing agent, defoamer, ketone solvent and leveling agent to the mixture II to obtain the product.

[0095] According to some embodiments of the present invention, the step S1 further includes a step of stirring under heating.

[0096] According to some embodiments of the present invention, the mixing conditions of the step S1 include:

[0097] 1) The temperature is below 60°C;

[0098] 2) Stir at 800 rpm - 1000 rpm for 30 - 60 minutes.

[0099] When the resin and the solvent are stirred and dissolved into each other, heat will be generated during stirring. Therefore, monitor the temperature during dissolution. If the temperature is too high, more solvent will volatilize, affecting the dissolution efficiency.

[0100] According to some embodiments of the present invention, the step S1 further includes a step of cooling the mixture I to below 40°C.

[0101] According to some embodiments of the present invention, the step S2 further includes a step of stirring at 600 - 800 rpm for 20 - 30 minutes and standing for more than 12 hours after adding silicone resin, polycarbonate diol resin, dispersant, pigment, filler and rheological aid.

[0102] According to some embodiments of the present invention, the step S2 further includes a step of grinding the mixture II.

[0103] According to some embodiments of the present invention, the grinding treatment is used to control the fineness of the mixture II below 10 μm.

[0104] According to some embodiments of the present invention, the grinding treatment is carried out using a three-roll mill or a high-viscosity sand mill.

[0105] According to some embodiments of the present invention, the ink further includes components B and C, and the preparation method further includes measuring components B and C and mixing them in proportion.

[0106] According to some embodiments of the present invention, the mass ratio of component B to component A is 2 - 4:100.

[0107] According to some embodiments of the present invention, the mass ratio of component C to component A is 5 - 15:100.

[0108] According to some embodiments of the present invention, the component B includes a coupling agent, and the component C includes a diluent.

[0109] According to another aspect of the present invention, a glass cover plate is provided, which includes a glass cover plate body and a covering ink layer arranged in a stacked manner, and the covering ink layer is prepared from the above-mentioned ink.

[0110] According to some embodiments of the present invention, the glass cover plate body is a 2D glass or a 2.5D glass.

[0111] According to some embodiments of the present invention, the glass cover plate body includes an edge area, and the covering ink layer is located in the edge area.

[0112] According to yet another aspect of the present invention, a terminal device is provided, which includes a first housing member and a second housing member. The first housing member and the second housing member are connected by an adhesive, and a covering ink layer is provided between the adhesive and the first housing member or between the adhesive and the second housing member, and the covering ink layer is prepared from the above-mentioned ink.

[0113] According to some embodiments of the present invention, the first housing member and / or the second housing member is a glass cover plate.

[0114] According to some embodiments of the present invention, the glass cover plate includes a glass cover plate body and the covering ink layer arranged in a stacked manner. The glass cover plate body includes an edge area, and the covering ink layer is located in the edge area.

[0115] According to some embodiments of the present invention, the terminal device includes a mobile phone or a smart wearable device.

[0116] According to some embodiments of the present invention, the smart wearable device includes a smart watch.

[0117] According to some embodiments of the present invention, the adhesive includes glue.

[0118] According to some embodiments of the present invention, the adhesive includes ethyl cyanoacrylate glue.

[0119] According to some embodiments of the present invention, the adhesive includes 8540 glue.

[0120] According to some embodiments of the present invention, the covering ink layer is printed on the glass cover plate by a screen printing process.

[0121] According to some embodiments of the present invention, the first housing member is a glass cover plate, which includes a glass cover plate body and the covering ink layer. The glass cover plate body includes a main body area and an edge area, and the first housing member is connected to the second housing member through the edge area.

[0122] According to some embodiments of the present invention, the terminal device includes functional components. The first housing component and the second housing component are connected by an adhesive to form a receiving space, and the functional components are located within the receiving space.

[0123] According to some embodiments of the present invention, the first housing component includes a middle frame, and the second housing component includes a glass cover plate. The glass cover plate can be fixed to the middle frame to enable the installation of functional components such as a display screen on the middle frame.

[0124] The solution of the present invention is particularly applicable to various white glass front cover plates that are bonded with 8540 glue and other glues and have high shear force requirements under ultra-low temperature conditions.

[0125] Additional aspects and advantages of the present invention will be given in part in the following description, will become apparent in part from the following description, or will be understood through the practice of the present invention. Specific Embodiments

[0126] The following will clearly and completely describe the concept of the present invention and the technical effects produced in combination with embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative efforts fall within the scope of protection of the present invention. The test methods used in the embodiments are conventional methods unless otherwise specified; the materials, reagents, etc. used, unless otherwise specified, can be reagents and materials obtained from commercial channels. Unless otherwise specified, the same parameter values are taken in each embodiment. The embodiments described below are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention.

[0127] In the description of the present invention, the description referring to terms such as "some embodiments" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0128] In the description of the present invention, if there is a description of I, II, etc., it is only for the purpose of distinguishing technical features and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence relationship of the indicated technical features.

[0129] 2D Glass Cover Plate: It refers to a glass cover plate component designed with a pure planar geometric shape, whose surface curvature radius is infinite and there are no arc machining features. The standard processing process chain of this type of cover plate includes: substrate blanking - fine CNC milling - hole drilling for functions - surface polishing - chemical strengthening process - silk-screen printing decoration - surface coating.

[0130] 2.5D Glass Cover Plate: It refers to a composite structure feature that combines a central planar area and a peripheral arc transition area, and its edge curvature radius is usually controlled within the range of 0.5 - 2.0 mm. Compared with the 2D glass cover plate, the following processes are added to its basic process: edge numerical control grinding, curved surface polishing. This structure is widely used in the touch panels of intelligent terminal devices (such as smart phones, smart watches, etc.), and has both the stability of planar display and the comfort of edge operation.

[0131] Silk-screen Printing Technology: A printing method based on the principle of ink penetration through the patterns on the screen. The system consists of five major elements: screen frame, photosensitive emulsion plate-making layer, squeegee, printing table, and printing substrate. During printing, a constant pressure is applied to the screen by the squeegee, so that the ink passes through the mesh holes in the pattern area and is transferred to the surface of the substrate to achieve precise graphic replication. This technology is suitable for decorative printing on hard substrates such as glass and ceramics.

[0132] HD8540 Instant Adhesive: Also known as "8540 glue", its chemical name is ethyl cyanoacrylate-based rapid-curing adhesive, which is composed of monomers, plasticizers, polymerization inhibitors, and stabilizers. It has the characteristics of rapid curing at room temperature, high bonding strength, and good transparency, and is suitable for structural bonding of substrates such as glass, metal, and plastic, especially suitable for temporary fixation and permanent encapsulation of precision electronic devices.

[0133] Low-temperature pulling force: The glass substrate printed with ink is adhesively bonded by HD8540 glue and subjected to a shear force test under low-temperature environmental conditions. Record the ratio of the failure load (F) to the bonding area (S) (F / S), and observe the proportion of the ink layer peeling area to comprehensively evaluate the low-temperature mechanical properties of the bonding system.

[0134] The information of the reagent manufacturers used in the following examples and comparative examples is shown in Table 1 below:

[0135] Table 1

[0136]

[0137] Examples 1-8

[0138] This example provides a decorative ink for a glass cover plate resistant to ultra-low temperatures, and its formula is shown in Table 2 below:

[0139] Table 2

[0140]

[0141] Comparative Examples 1-6

[0142] This example provides a decorative ink for a glass cover plate, and its formula is shown in Table 3 below:

[0143] Table 3

[0144]

[0145] The ink preparation processes in the above Examples 1-8 and Comparative Examples 1-6 are as follows:

[0146] 1) Sequentially add Resin 1, PMA, and DBE to the ink reaction kettle, stir at 900 r / min for 45 minutes (the temperature is controlled below 60 °C); after confirming that there is no obvious granular liquid resin, stop stirring and cool to below 40 °C.

[0147] 2) Based on Step 1, add the corresponding proportions of Resin 2, Resin 3, BYK161, CR-828, BF-20, and Claytone APA bentonite, stir at 700 r / min for 25 minutes, let stand for more than 12 hours, and put it into a three-roll mill or a high-viscosity sand mill for grinding; the number of grinding passes and the grinding time are determined according to the fineness ground out. When the grinding fineness is below 10 μm, take it out.

[0148] 3) Based on Step 2, add the corresponding proportions of DESMODUR BL 3175A, BYK011, isophorone, and BYK-333, stir at 700 r / min for 25 minutes to obtain Component A.

[0149] 4) Weigh Components B and C in proportion to obtain the product.

[0150] The ink application processes in the above Examples 1-8 and Comparative Examples 1-6 are as follows:

[0151] Take glass from the same source as the material, and form a coating on the glass through the following operations: use a 250-mesh screen to print 4 layers, with each layer being 7 - 9 μm thick. For the first three prints, after each print, bake at 150 °C for 5 minutes; after the last print, bake at 150 °C for 30 minutes.

[0152] Performance testing:

[0153] Take the coating obtained from the above operations for performance testing. The methods and instruments used during the testing are described as follows:

[0154] 1. Film thickness testing instrument: Mitutoyo micrometer for thin plates No. 293 - 240 - 30 made in Japan.

[0155] 2. The OD value testing instrument is Linshang LS117. Test according to the instruction manual. After turning on the machine, directly place it on the testing platform and read the data.

[0156] 3. The adhesion test refers to the 7 - grid method in GB / T 13217.7 - 2023 "Test Method for Ink Adhesion".

[0157] 4. The test method for the pencil hardness with a 300 - g force is determined according to Method A in GB / T 6739 - 2022 "Paints and Varnishes - Determination of Film Hardness by the Pencil Method".

[0158] 5. Low - temperature shear force test method: On the already made sample plate, mix the AB glue of 8540 glue evenly and then apply the glue. Then use the same glass material printed with ink for capping, and then press a 50 - g weight on it. Place it in an oven at 60 °C and bake for 20 minutes; take out the sample plate, place the glass vertically in a cryogenic (-88 °C) shear force device to measure the breaking force. After completion, calculate the size of the glue - applied area and obtain F / S.

[0159] The test results of the samples made from the inks of the examples and comparative examples are shown in Tables 4 and 5 as follows:

[0160] Table 4

[0161]

[0162] Table 5

[0163]

[0164] * Note: The OD value test standards in Tables 4 and 5 only represent the OD value standards of some high - whiteness products.

[0165] In addition, it is verified that for the ink of the embodiment of the present invention, after preparation for 0 hour, 4 hours, 8 hours, 16 hours and 24 hours, when printing a four-layer sample board, the crosshatch boiling and crosshatch test results are all below level 1, and the shear force F / S at ultra-low temperature is 1.5. This shows that the activation period of the ink of the present invention is more than 24 hours.

[0166] As can be seen from Tables 4 and 5, when only one or two of epoxy resin, silicone resin or polycarbonate diol resin modified with polyurethane resin are used, the problems of ultra-low temperature resistance, high draw force and high adhesion cannot be solved simultaneously. When only epoxy resin and silicone resin modified with polyurethane resin are added, it is easy to fall off under ultra-low temperature and high draw force, while the adhesion of the ink prepared from the resin system containing only polycarbonate diol resin or containing both polycarbonate diol resin and silicone resin is weak.

[0167] In the resin composition of the present invention, the epoxy groups in the polyurethane-modified epoxy resin can provide a high crosslinking density, enhance hardness and chemical resistance. Among them, the urethane bond (-NHCOO-) in the polyurethane segment alleviates the brittleness of the epoxy resin and improves flexibility; the amino-functional silicone resin contains amino functional groups, which react with the epoxy groups of the epoxy resin to open the ring, enhance the interfacial crosslinking density and improve adhesion. The Si-O-Si group therein has excellent high temperature resistance and low surface energy, improving the stability of the paint film at extreme temperatures. The flexible carbonate long chain in the polycarbonate diol resin provides the movement ability of the molecular chain, preventing embrittlement at low temperatures and alleviating thermal stress at high temperatures. At ultra-low temperature (-88 °C), the flexible chain segment of PCD absorbs external force through molecular chain slip to avoid brittle fracture of the paint film; the siloxane chain segment of the silicone resin reduces the low temperature shrinkage stress; the epoxy resin provides sufficient crosslinking density to maintain structural integrity. Through the synergistic effect of the three resins, the performance boundaries of single resin or two resins in terms of temperature resistance, flexibility, adhesion, etc. are broken through, and finally multiple advantages such as high adhesion and high ultra-low temperature draw force are achieved.

[0168] In summary, the present invention adopts an ink formulation with a synergistic combination of three resins. By optimizing the interfacial compatibility between resins and the movement ability of molecular chain segments, the wetting and dispersion effect of the resin on the powder is significantly enhanced, thereby constructing a uniform and dense paint film structure. Compared with traditional single or two-component resin-based inks, the technical solution of the present invention exhibits the following technical advantages:

[0169] 1) Breakthrough in activation period regulation: The resin synergistic system effectively delays the crosslinking and curing reaction process of the ink, enabling the system to maintain a stable processing window for 24 hours, with stable ink viscosity, ensuring that the construction performance is not affected by time.

[0170] 2) Improved covering efficiency: Through the multiple wrapping and directional arrangement of resin on pigment particles, excellent covering performance with an OD value ≥ 2.2 can be achieved at a dry film thickness of 30 μm, reducing the coating process by 2 - 3 layers compared to the conventional system.

[0171] 3) Optimized printing suitability: The single - component system maintains a constant rheology during continuous printing, ensuring consistent gloss, DOI, and film thickness uniformity on the printed surface.

[0172] 4) Innovative grinding efficiency: The layered structure of bentonite produces a peeling effect under shear force, and its nanoscale interlayer domain provides a dispersion channel for BF - 20 nanoscale barium sulfate, enabling the particle size to be stably controlled at ≤ 10 μm, significantly reducing the grinding energy consumption.

[0173] 5) Resistance to medium erosion: The paint film of the present invention has excellent barrier properties against chemical media such as acids, alkalis, and solvents.

[0174] 6) Low - temperature rheological properties: In an ultra - low - temperature environment, the synergistic cooperation between resin compositions enables the ink to have both high shear force and ensure that it is not easily shed.

[0175] 7) Stable adhesion: It has good adhesion within a wide temperature range.

[0176] 8) Good flexibility: Even at ultra - low temperatures, the paint film of the present invention still has good flexibility.

[0177] 9) Environmental protection: Low - odor characteristics, higher acceptance by employees, more environmentally friendly and more conducive to improving production efficiency.

[0178] The above has made a detailed description of the embodiments of the present invention, but the present invention is not limited to the above - mentioned embodiments. Within the scope of knowledge possessed by those of ordinary skill in the art, various changes can be made without departing from the gist of the present invention.

Claims

1. A decorative ink for glass cover plates, characterized in that: It includes component A; the component A includes raw materials in the following parts by weight: 15 - 45 parts of resin composition, 30 - 50 parts of pigment, 3 - 8 parts of filler, 3 - 8 parts of curing agent, 5.5 - 12.5 parts of auxiliary agent, and 6 - 22 parts of solvent. The resin composition includes polyurethane-modified epoxy resin, silicone resin, and polycarbonate diol resin. Among them, the silicone resin contains amino groups, and the weight ratio of polyurethane-modified epoxy resin, silicone resin, and polycarbonate diol resin in the resin composition is 1 - 5:1 - 5:1 - 5.

2. The decorative ink for glass cover plates according to claim 1, characterized in that: The polyurethane-modified epoxy resin has at least one of the following characteristics: 1) The glass transition temperature is 120 - 130 °C; 2) The epoxy equivalent is 170 - 250 g / eq; The silicone resin has at least one of the following characteristics: 1) Amine equivalent: 250 - 270 grams / NH; 2) Solid content ≥ 97%; 3) Kinematic viscosity is between 3500 ± 1000 cSt; The polycarbonate diol resin has at least one of the following characteristics: 1) Hydroxyl value is between 50 - 65 KOH / g; 2) Solid content ≥ 97%; 3) The pencil hardness after curing is < F, and the test condition is 300 g force.

3. The decorative ink for glass cover plates according to claim 1, wherein: The polyurethane-modified epoxy resin includes NPER-133L produced by South Asia Company or HyPox UA10 produced by CVC Thermosetting Specialties Division; and / or, the silicone resin includes DOWSIL™ 3055 of Dow Corning Corporation; and / or, the polycarbonate diol resin includes T5652 polycarbonate diol resin produced by Asahi Kasei Corporation.

4. The decorative ink for glass cover plates according to claim 1, characterized in that: The curing agent includes blocked isocyanate.

5. The decorative ink for glass cover plates according to claim 1, characterized in that: The median particle size of the pigment is between 0.15 - 0.22 μm.

6. The decorative ink for glass cover plates according to any one of claims 1 to 5, characterized in that: The ink includes 100 parts by weight of component A, 2 - 4 parts by weight of component B, and 5 - 15 parts by weight of component C; among them, the auxiliary agent includes dispersant, defoamer, rheological aid, and leveling agent. The component A includes raw materials in the following parts by weight: 15 - 45 parts of resin composition, 30 - 50 parts of pigment, 3 - 8 parts of filler, 3 - 8 parts of curing agent, 4 - 8 parts of dispersant, 0.5 - 2 parts of defoamer, 0.5 - 1.5 parts of rheological aid, 0.5 - 1 part of leveling agent, and 6 - 22 parts of solvent. The resin composition includes polyurethane-modified epoxy resin, silicone resin, and polycarbonate diol resin; the pigment includes white pigment; the dispersant includes BYK 161; the defoamer includes BYK011, the leveling agent includes BYK 333; the rheological aid includes Claytone APA bentonite; the component B includes coupling agent; the component C includes diluent, and the diluent includes 200# solvent oil.

7. A method for preparing a decorative ink for a glass cover plate according to any one of claims 1 to 5, characterized in that: The auxiliary agent includes dispersant, defoamer, rheological aid, and leveling agent, and the solvent includes ester solvent and ketone solvent; The preparation method includes the following steps: S1. Mix the polyurethane-modified epoxy resin with the ester solvent to obtain mixture I; S2. Add the silicone resin, polycarbonate diol resin, dispersant, pigment, filler, and rheological aid to the mixture I to obtain mixture II; S3. Add a curing agent, an antifoaming agent, a ketone solvent and a leveling agent to the mixture II to obtain the product.

8. A glass cover plate, characterized in that: It includes a glass cover plate body and a covering ink layer arranged in a stacked manner, and the covering ink layer is prepared from the decorative ink for glass cover plates according to any one of claims 1 to 6.

9. A terminal device, characterized in that: It includes a first housing part and a second housing part. The first housing part and the second housing part are connected by an adhesive, and a covering ink layer is provided between the adhesive and the first housing part or between the adhesive and the second housing part. The covering ink layer is prepared from the decorative ink for glass cover plates according to any one of claims 1 to 6.

10. The terminal device according to claim 9, characterized in that: The first housing part and / or the second housing part is a glass cover plate. The glass cover plate includes a glass cover plate body and the covering ink layer arranged in a stacked manner. The glass cover plate body includes an edge region, and the covering ink layer is located in the edge region.

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