Preparation method of high-weather-resistance high-definition light box advertising paint

Abstract

The invention relates to the technical field of polymer coatings, in particular to a preparation method of a high-weather-resistance high-definition light box advertising coating, which comprises the following steps: (a) preparing an outer layer coating: (a1) weighing principle components, (a2) adding into a solvent system, (a3) carrying out first mixing treatment; (a4) adding 0.5-1.0 part by weight of an ultraviolet light absorber and 0.15 part by weight of a photoinitiator; (a5) filtering and purifying to obtain an outer coating finished product; (b) preparing an inner-layer coating: (b1) weighing the following components; (b2) adding the components into a solvent system; (b3) adding 0.1-0.3 part by weight of a metal complex catalyst; and (b4) carrying out second mixing treatment to obtain an inner-layer coating finished product. By optimizing a coating formula and a preparation process, the weather resistance of the coating in an outdoor environment is improved, and meanwhile, the excellent optical performance of the coating is ensured, so that the requirements of lamp box advertisements on efficient and high-quality display materials are met.

Description

Technical Field

[0001] This invention relates to the field of polymer coating technology, and in particular to a method for preparing a high weather-resistant and high-definition lightbox advertising coating. Background Technology

[0002] With the continuous development of the advertising industry, lightbox advertising, as an important form of advertising display, is widely used in various outdoor and indoor locations. For lightbox advertising materials, high weather resistance and high-definition display effects are crucial performance requirements. In outdoor environments, lightbox advertising materials need to withstand long-term ultraviolet radiation, high and low temperature changes, rain erosion, and other harsh conditions. If weather resistance is insufficient, the material is prone to fading, aging, and cracking, seriously affecting the display effect and lifespan of the advertisement. Coatings can extend the lifespan of lightboxes, but the weather resistance of the coating mainly depends on the ability of the resin matrix and stabilizer system to resist environmental factors such as ultraviolet radiation, humidity, and temperature changes. Often, some substances need to be added to improve its weather resistance. Clarity requires the coating to have high transparency, low haze, and excellent light transmittance; the fewer additives, especially fillers, the better.

[0003] CN112111211B discloses an environmentally friendly coating, published on October 22, 2021. This patent relates to an environmentally friendly coating composed of polyester resin, epoxy resin, titanium dioxide, barium sulfate, formaldehyde-removing activated carbon, and other raw materials, exhibiting good antibacterial effects and long-lasting formaldehyde removal capabilities. However, this technical solution primarily optimizes environmental performance and antibacterial function, without fully considering the coating's weather resistance in outdoor environments, especially its resistance to extreme conditions such as ultraviolet radiation and extreme temperature changes. Furthermore, the coating formulation lacks optimized design for the coating's optical properties, potentially resulting in an inability to achieve high-definition display effects in lightbox advertising applications. CN111876043B discloses a water-based coating, published on October 8, 2021. This patent relates to a water-based coating composed of acrylic emulsion, graphene oxide, lotus leaf hydrophobic agent, and other raw materials, exhibiting excellent stain resistance, water resistance, and corrosion resistance. While this technology demonstrates excellent stain and water resistance, its insufficient focus on UV protection and long-term outdoor weather resistance may lead to aging and fading issues when the coating is exposed to outdoor environments for extended periods. Furthermore, the coating formulation does not explicitly address optimization of light transmittance and clarity, potentially failing to meet the high-definition display requirements of lightbox advertising.

[0004] The above problems indicate that existing coating technologies still have certain shortcomings in comprehensively optimizing high weather resistance and high-definition display performance. Summary of the Invention

[0005] To overcome the above deficiencies, this invention provides a method for preparing a high-weather-resistant and high-definition lightbox advertising coating. By optimizing the coating formulation and preparation process, the coating's weather resistance in outdoor environments is improved, while ensuring its excellent optical performance, thereby meeting the demand of lightbox advertising for efficient and high-quality display materials.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for preparing a high weather-resistant, high-definition lightbox advertising coating includes the following steps:

[0008] (a) Preparation of outer coating:

[0009] (a1) Weigh the following components:

[0010] 65-70 parts by weight of polyurethane acrylate resin;

[0011] 5-8 parts by weight of mercaptosiloxane compound;

[0012] 8-12 parts by weight of multifunctional thiol crosslinking agent;

[0013] 3-5 parts by weight of polymerizable liquid crystal monomer;

[0014] (a2) Add to the solvent system:

[0015] 75-85 parts by weight of propylene glycol methyl ether acetate;

[0016] 25-30 parts by weight of propylene glycol phenyl ether;

[0017] (a3) First mixing treatment;

[0018] (a4) Add 0.5-1.0 parts by weight of ultraviolet absorber and 0.15 parts by weight of photoinitiator;

[0019] (a5) Filtration and purification to obtain the finished outer coating;

[0020] (b) Preparation of inner coating:

[0021] (b1) Weigh the following components:

[0022] 70-75 parts by weight of organosilicon acrylate resin;

[0023] 10-15 parts by weight of bis(4-hydroxyphenyl) disulfide;

[0024] 1.0 parts by weight of multifunctional acrylate crosslinking agent;

[0025] (b2) Add to the solvent system:

[0026] 70-80 parts by weight of propylene glycol methyl ether acetate;

[0027] 25-35 parts by weight of propylene glycol tert-butyl ether;

[0028] (b3) Add 0.1-0.3 parts by weight of a metal complex catalyst;

[0029] (b4) Second mixing process to obtain the inner coating finished product.

[0030] The high weather-resistant, high-definition lightbox advertising coating designed in this scheme is based on the layered dynamic response driven by the thermal field of the lightbox:

[0031] The outer layer refers to the environmental contact layer. When the light box is working, the temperature is 50-60℃. The tetrasulfide bond (-S4-) in the outer coating component pentaerythritol tetrakis(3-mercaptopropionic acid) undergoes homolytic cleavage to generate sulfur free radicals (·SR). Through free radical chain transfer (·S-R+R-S3→R-S4-R), the surface microcracks caused by ultraviolet rays are repaired in real time. At the same time, it can polymerize liquid crystal monomers to self-assemble into 25nm ordered micro-regions. Its Bragg diffraction cancels scattering loss and maintains a transmittance of >90%.

[0032] The inner layer refers to the layer that is in direct contact with the light box. As a thermal stress-bearing layer, in the high-temperature zone of 70-80℃ near the light source, the disulfide bond (-SS-) in the bis(4-hydroxyphenyl) disulfide undergoes a disproportionation reaction, and the ion pairs migrate to the deep crack sites to recombine and form bonds, consuming heat expansion energy. Meanwhile, the organosilicon acrylate resin blocks heat transfer with its high bond energy of Si-O bonds. The three work together to construct a gradient protection system of "outer layer dynamic self-healing - deep crack repair - body thermal insulation", which solves the essential contradiction between light transmittance and weather resistance.

[0033] Preferably, in (a1), the multifunctional thiol crosslinking agent is pentaerythritol tetrakis(3-mercaptopropionic acid) ester; and the polymerizable liquid crystal monomer is 4,4-biphenyl di(6-acryloyloxyhexyl) ether.

[0034] Preferably, in (a4), the photoinitiator is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0035] Preferably, in (a3), the first mixing treatment is to stir at 400-600 rpm for 35-50 min at 40±2℃.

[0036] Preferably, in (b1), the organosilicon acrylate resin is a diacryloyloxy polysiloxane; and the multifunctional acrylate crosslinking agent is trimethylolpropane triacrylate ethoxylate.

[0037] Preferably, in (b3), the metal complex catalyst is an organobismuth complex.

[0038] Preferably, in (b4), the second mixing treatment is ultrasonic dispersion at 35-50 kHz for 30-40 min.

[0039] This solution proposes a high weather-resistant and high-definition lightbox advertising coating, which includes the preparation of an outer coating and an inner coating using the aforementioned method for preparing the high weather-resistant and high-definition lightbox advertising coating.

[0040] This solution also proposes an application method for the aforementioned high weather resistance and high definition lightbox advertising coating, including the following steps:

[0041] (c1) The surface of the lightbox substrate is coated with an inner layer of paint;

[0042] (c2) Curing treatment;

[0043] (c3) Apply an outer coating;

[0044] (c4) Final curing heat treatment.

[0045] Preferably, (c2) the curing treatment is heating at 80±2℃ for 10-20 min; (c4) the final curing heat treatment is irradiation with a light source wavelength of 50-400nm and a light intensity of 50-60mW / cm for 2-5 min, followed by heating at 55-65℃ for 10-20 min.

[0046] Preferably, after curing (c2), the thickness of the inner dry film is 35±1μm; after final curing (c4), the thickness of the outer dry film is 20±1μm.

[0047] Simultaneously, hexyl biphenyl glycol ester self-assembles into 25 nm smectic microregions during programmed cooling, and its periodic structure enhances visible light transmission through Bragg diffraction; the organosilicon component migrates to form a hydrophobic barrier to block aging factors, ultimately achieving a dynamic balance between damage self-healing and optical transparency.

[0048] Compared with the prior art, the advantages of this invention are:

[0049] This invention utilizes the gradient temperature distribution characteristics of the heat generated during the operation of the lightbox through component design. The outer layer activates tetrasulfide free radicals to repair surface micro-damage and dynamically maintains optical stability in the liquid crystal micro-area. The inner layer triggers disulfide ion migration to dissipate heat dissipation stress. This triple response precisely matches the thermal field distribution of the lightbox, improving the weather resistance of the coating in outdoor environments while ensuring its excellent optical performance, thereby meeting the demand of lightbox advertising for efficient and high-quality display materials. Detailed Implementation

[0050] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0051] General Implementation Examples

[0052] A method for preparing a high weather-resistant, high-definition lightbox advertising coating includes the following steps:

[0053] (a) Preparation of outer coating:

[0054] (a1) Weigh the following components:

[0055] 65-70 parts by weight of polyurethane acrylate resin (synthesized from hexamethylene diisocyanate trimer and hydroxyethyl acrylate);

[0056] 5-8 parts by weight of a mercaptosiloxane compound (mercaptopropyl-terminated polydimethylsiloxane, mercapto value 1.0-1.5 mmol / g);

[0057] 8-12 parts by weight of a multifunctional thiol crosslinking agent (pentaerythritol tetrakis(3-mercaptopropionic acid) ester);

[0058] 3-5 parts by weight of polymerizable liquid crystal monomer (4,4-biphenyl di(6-acryloyloxyhexyl) ether);

[0059] (a2) Add to the solvent system:

[0060] 75-85 parts by weight of propylene glycol methyl ether acetate;

[0061] 25-30 parts by weight of propylene glycol phenyl ether;

[0062] (a3) First mixing treatment: mechanically stir at 400-600 rpm for 35-50 min at 40±2℃;

[0063] (a4) Add:

[0064] 0.5-1.0 parts by weight of ultraviolet absorber (2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol);

[0065] 0.15 parts by weight of photoinitiator (2,4,6-trimethylbenzoyl-diphenylphosphine oxide);

[0066] (a5) After filtration through a 1μm nylon membrane, the outer coating is obtained.

[0067] (b) Preparation of inner coating:

[0068] (b1) Weigh the following components:

[0069] 70-75 parts by weight of organosilicon acrylate resin (double-terminated acryloxy polysiloxane, acryloxy value 0.35±0.05mol / kg);

[0070] 10-15 parts by weight of bis(4-hydroxyphenyl) disulfide;

[0071] 1.0 parts by weight of multifunctional acrylate crosslinking agent (ethoxylated trimethylolpropane triacrylate);

[0072] (b2) Add to the solvent system:

[0073] 70-80 parts by weight of propylene glycol methyl ether acetate;

[0074] 25-35 parts by weight of propylene glycol tert-butyl ether;

[0075] (b3) Add 0.1-0.3 parts by weight of a metal complex catalyst (organobismuth complex BorchiKat315).

[0076] (b4) Second mixing treatment: ultrasonic dispersion at 35-50kHz for 30-40min to obtain the inner coating product.

[0077] Outer layer polyurethane acrylate resin: provides mechanical toughness and resists outdoor wind loads and impacts;

[0078] Mercaptopropyl-terminated polydimethylsiloxane: migrates to the surface to form a hydrophobic barrier, blocking rainwater erosion;

[0079] Pentaerythritol tetra(3-mercaptopropionic acid) ester (tetrasulfide bond): Triggers free radical chain transfer at 50-60℃, self-repairing surface microcracks caused by ultraviolet radiation;

[0080] 4,4-Biphenyl di(6-acryloyloxyhexyl) ether (liquid crystal monomer): self-assembled 25nm ordered micro-regions, suppressing light scattering through Bragg diffraction to maintain >90% transmittance;

[0081] Propylene glycol phenyl ether (high boiling point solvent): slows down the surface drying rate and ensures the orderly arrangement of liquid crystal molecules;

[0082] 2,4,6-Trimethylbenzoyl-diphenylphosphine oxide: a deep-curing photoinitiator that penetrates the coating to achieve complete crosslinking;

[0083] Inner layer double-terminated acryloxy polysiloxane: blocks heat conduction from the light box with Si-O bonds (452kJ / mol), reducing temperature fluctuations in the outer layer;

[0084] Bis(4-hydroxyphenyl) disulfide: undergoes a disproportionation reaction at 70-80℃, and ion pairs migrate to repair deep cracks caused by thermal stress.

[0085] Ethylene oxide trimethylolpropane triacrylate: Constructs a dense cross-linked network to resist long-term thermal expansion deformation of the light box;

[0086] Organic bismuth catalyst BorchiKat315: Low-temperature catalytic click reaction of mercapto-acrylate, avoiding high-temperature yellowing that affects the color reproduction of advertisements.

[0087] Functional synergy logic: Outer layer (tetrasulfide bond + liquid crystal) dynamically repairs UV damage and optically enhances light transmission → Middle layer (siloxane) provides thermal insulation → Bottom layer (disulfide bond) dissipates heat dissipation stress, a three-in-one approach to ensure high weather resistance and image clarity of lightbox advertisements under outdoor heat / light fields.

[0088] Example 1

[0089] (a) Preparation of outer coating:

[0090] (a1) Weigh:

[0091] 67 parts by weight of polyurethane acrylate resin (hexamethylene diisocyanate trimer-hydroxyethyl acrylate copolymer);

[0092] 6 parts by weight of mercaptopropyl-terminated polydimethylsiloxane (mercaptovalue 1.3 mmol / g);

[0093] 10 parts by weight of pentaerythritol tetrakis(3-mercaptopropionic acid);

[0094] 4 parts by weight of 4,4-biphenyl di(6-acryloyloxyhexyl) ether;

[0095] (a2) Add solvent:

[0096] 80 parts by weight of propylene glycol methyl ether acetate (0.02% moisture);

[0097] 28 parts by weight of propylene glycol phenyl ether (4 ppm peroxide);

[0098] (a3) First mixing treatment: Stir at 500 rpm for 45 min at 40°C;

[0099] (a4) Add:

[0100] 0.8 parts by weight of 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol;

[0101] 0.15 parts by weight of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide;

[0102] (a5) Filtered through a 1μm nylon membrane.

[0103] (b) Preparation of inner coating:

[0104] (b1) Weighing:

[0105] 72 parts by weight of diacryloyloxy polysiloxane (acryloyl oxygen value 0.35 mol / kg);

[0106] 12 parts by weight of bis(4-hydroxyphenyl) disulfide;

[0107] 1.0 parts by weight of ethoxylated trimethylolpropane triacrylate;

[0108] (b2) Add solvent:

[0109] 75 parts by weight of propylene glycol methyl ether acetate (acid value 0.04 mg KOH / g);

[0110] 30 parts by weight of propylene glycol tert-butyl ether;

[0111] (b3) Add 0.2 parts by weight of the organic bismuth complex BorchiKat315;

[0112] (b4) Second mixing treatment: ultrasonic dispersion at 40 kHz for 35 min.

[0113] Example 2

[0114] (a) Preparation of outer coating:

[0115] (a1) Weigh:

[0116] 65 parts by weight of polyurethane acrylate resin;

[0117] 5 parts by weight of mercaptopropyl-terminated polydimethylsiloxane (mercaptovalue 1.1 mmol / g);

[0118] 8 parts by weight of pentaerythritol tetrakis(3-mercaptopropionic acid);

[0119] 3 parts by weight of 4,4-biphenyl di(6-acryloyloxyhexyl) ether;

[0120] (a2) Add solvent:

[0121] 75 parts by weight of propylene glycol methyl ether acetate (0.03% moisture);

[0122] 25 parts by weight of propylene glycol phenyl ether (2 ppm peroxide);

[0123] (a3) First mixing treatment: Stir at 400 rpm for 50 min at 42℃;

[0124] (a4) Add:

[0125] 0.5 parts by weight of 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol;

[0126] 0.15 parts by weight of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide;

[0127] (a5) Filtered through a 1μm nylon membrane.

[0128] (b) Preparation of inner coating:

[0129] (b1) Weighing:

[0130] 70 parts by weight of bisacryloyloxy polysiloxane (acryloyl oxygen value 0.32 mol / kg);

[0131] 10 parts by weight of bis(4-hydroxyphenyl) disulfide;

[0132] 1.0 parts by weight of ethoxylated trimethylolpropane triacrylate;

[0133] (b2) Add solvent:

[0134] 70 parts by weight of propylene glycol methyl ether acetate (acid value 0.03 mg KOH / g);

[0135] 25 parts by weight of propylene glycol tert-butyl ether;

[0136] (b3) Add 0.1 parts by weight of BorchiKat315;

[0137] (b4) Second mixing treatment: ultrasonic dispersion at 35 kHz for 40 min.

[0138] Example 3

[0139] (a) Preparation of outer coating:

[0140] (a1) Weigh:

[0141] 70 parts by weight of polyurethane acrylate resin;

[0142] 8 parts by weight of mercaptopropyl-terminated polydimethylsiloxane (mercaptovalue 1.5 mmol / g);

[0143] 12 parts by weight of pentaerythritol tetrakis(3-mercaptopropionic acid);

[0144] 5 parts by weight of 4,4-biphenyl di(6-acryloyloxyhexyl) ether;

[0145] (a2) Add solvent:

[0146] 85 parts by weight of propylene glycol methyl ether acetate (0.01% moisture);

[0147] 30 parts by weight of propylene glycol phenyl ether (1 ppm peroxide);

[0148] (a3) First mixing treatment: Stir at 600 rpm for 35 min at 38°C;

[0149] (a4) Add:

[0150] 1.0 parts by weight of 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol;

[0151] 0.15 parts by weight of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide;

[0152] (a5) Filtered through a 1μm nylon membrane.

[0153] (b) Preparation of inner coating:

[0154] (b1) Weighing:

[0155] 75 parts by weight of bisacryloyloxy polysiloxane (acryloyl oxygen value 0.38 mol / kg);

[0156] 15 parts by weight of bis(4-hydroxyphenyl) disulfide;

[0157] 1.0 parts by weight of ethoxylated trimethylolpropane triacrylate;

[0158] (b2) Add solvent:

[0159] 80 parts by weight of propylene glycol methyl ether acetate (acid value 0.05 mg KOH / g);

[0160] 35 parts by weight of propylene glycol tert-butyl ether;

[0161] (b3) Add 0.3 parts by weight of BorchiKat315;

[0162] (b4) Second mixing treatment: ultrasonic dispersion at 50 kHz for 30 min.

[0163] Comparative Example 1

[0164] The difference from Example 1 is that the outer layer is removed from pentaerythritol tetrakis(3-mercaptopropionic acid) and the amount of polyurethane acrylate resin is increased to 77 parts by weight.

[0165] Comparative Example 2

[0166] The difference from Example 1 is that the outer layer of 4,4-biphenyl di(6-acryloyloxyhexyl) ether is removed, and the amount of polyurethane resin is increased to 71 parts by weight.

[0167] Comparative Example 3

[0168] The difference from Example 1 is that the mercaptopropyl-terminated polydimethylsiloxane was removed from the outer layer, and the amount of polyurethane resin was increased to 73 parts by weight.

[0169] Comparative Example 4

[0170] The difference from Example 1 is that the inner layer is free of bis(4-hydroxyphenyl) disulfide and the amount of silicone resin is increased to 84 parts by weight.

[0171] Comparative Example 5

[0172] The difference from Example 1 is that BorchiKat315 was removed from the inner layer, and the amount of propylene glycol tert-butyl ether in the solvent was increased to 30.2 parts by weight.

[0173] Comparative Example 6

[0174] The difference from Example 1 is that the outer layer of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide is removed, and the amount of ultraviolet absorber is increased to 0.95 parts by weight.

[0175] Comparative Example 7

[0176] The difference from Example 1 is that the outer tetrasulfide crosslinking agent is increased to 18 parts by weight, and the polyurethane resin is reduced to 59 parts by weight.

[0177] Comparative Example 8

[0178] The difference from Example 1 is that the outer layer liquid crystal monomer is increased to 8 parts by weight, and the polyurethane resin is reduced to 63 parts by weight.

[0179] Comparative Example 9

[0180] The difference from Example 1 is that the inner layer of bis(4-hydroxyphenyl) disulfide is increased to 22 parts by weight, and the silicone resin is reduced to 62 parts by weight.

[0181] Comparative Example 10

[0182] The difference from Example 1 is that the outer photoinitiator is increased to 0.45 parts by weight and the ultraviolet absorber is reduced to 0.5 parts by weight.

[0183] Application Example 1

[0184] Examples 1-3, Comparative Examples 1-10, and the application methods of the high weather-resistant and high-definition lightbox advertising coatings and commercially available coatings include the following steps:

[0185] (c1) The surface of the lightbox substrate is coated with an inner layer of paint;

[0186] (c2) Curing treatment: Heat at 80℃ for 15 minutes;

[0187] (c3) Apply an outer coating;

[0188] (c4) Final curing heat treatment: 350-400nm, light intensity 55mW / cm, irradiation for 3min, followed by heating at 60℃ for 15min;

[0189] (c2) After curing, the thickness of the inner dry film is 35±1μm; (c4) After final curing, the thickness of the outer dry film is 20±1μm.

[0190] Application Example 2

[0191] Examples 1-3, Comparative Examples 1-10, and the application methods of the high weather-resistant and high-definition lightbox advertising coatings and commercially available coatings include the following steps:

[0192] (c1) The surface of the lightbox substrate is coated with an outer layer of paint;

[0193] (c2) Curing treatment: 350-400nm, light intensity 55mW / cm, irradiation for 3min, followed by heating at 60℃ for 15min;

[0194] (c3) Apply inner coating;

[0195] (c4) Final curing heat treatment: Heat at 80℃ for 15 min;

[0196] (c4) After curing, the thickness of the inner dry film is 35±1μm; (c2) After final curing, the thickness of the outer dry film is 20±1μm.

[0197] Performance testing:

[0198] Before applying high weather-resistant, high-definition lightbox advertising coatings and commercially available coatings, the light transmittance of the lightbox is tested according to ASTM D1003, and the result is Q0.

[0199] High weather-resistant and high-definition lightbox advertising coatings and commercially available coatings were applied. The light transmittance of the lightbox was measured by a light transmittance meter Q1, and the coating peel strength was tested according to ISO 4624, with a result of N0.

[0200] High weather-resistant and high-definition lightbox advertising coatings and commercially available coatings, after working for 500 hours under ambient temperature of 30℃ and humidity of 80-90%, lightbox transmittance intensity meter Q2 and coating peel strength meter N1;

[0201] Calculate the initial optical attenuation rate L1 = (Q0 - Q1) / Q0 × 100%;

[0202] After 500 hours of operation, the optical attenuation rate L2 = (Q0 - Q1) / Q0 × 100%;

[0203] After 500 hours of operation, the peel strength retention rate η = N1 / N0 × 100%.

[0204] The test results are shown in Table 1.

[0205] Table 1. Performance test results of examples, comparative examples, and commercially available coatings.

[0206] The above data shows that, under correct coating conditions, the embodiment repairs UV microcracks in real time through the free radical chain transfer of tetrasulfide bonds at 50-60℃, suppresses light scattering through the orderly assembly of liquid crystal micro-regions, and consumes heat dissipation stress through the migration of disproportionated ions of disulfide at 70-80℃. Combined with the hydrophobic siloxane barrier and the integrity of the photocuring network, a synergistic protection system is formed. Specifically, the embodiment utilizes the thermal gradient of the lightbox operation. The outer layer of the lightbox at 50-60℃ provides conditions for dynamic repair of damage through tetrasulfide bonds; the bottom layer at 70-80℃ allows for the consumption of heat dissipation stress through the migration of disproportionated ions of disulfide, while Si-O bonds block heat conduction. Therefore, the inner layer is coated first to ensure that high-temperature curing does not damage the dynamic bonds of the outer layer, and the solvent is formulated with high-boiling-point propylene glycol phenyl ether to ensure the orderly assembly of liquid crystals. This breaks the vicious cycle in traditional lightbox coatings where improved weather resistance leads to decreased light transmittance, and improved transmittance leads to decreased weather resistance.

[0207] Compared to Example 1, Comparative Example 1 showed that the absence of tetrasulfide bonds led to irreversible accumulation of surface cracks, and ultraviolet penetration caused photo-oxidative aging of the substrate; Comparative Example 2 showed that the absence of liquid crystal monomers resulted in a disordered phase in the coating, with a doubling of visible light scattering rate; Comparative Example 3 showed that the loss of the hydrophobic barrier of mercaptosiloxanes led to water vapor penetration and blistering and delamination at the interface; Comparative Example 4 showed that the lack of disulfide ion migration mechanism led to the propagation of thermal stress cracks; Comparative Example 5 showed that the lack of catalyst resulted in insufficient crosslinking rate of mercapto-acrylate, and the loose network accelerated environmental erosion; Comparative Example 6 showed that the absence of photoinitiator resulted in incomplete curing network, and powdering and peeling were the dominant failures; Comparative Examples 7 / 8 showed that excessive tetrasulfide bonds / liquid crystals initiated phase separation, and crosslinking imbalance and optical mismatch coexisted; Comparative Example 9 showed that excessive disulfide induced yellowing as a side reaction, and the precipitation of small molecules damaged the interface; Comparative Example 10 showed that excessive photoinitiator led to a sharp increase in curing shrinkage stress, and microcracks spontaneously nucleated.

[0208] In Application Example 2, the reverse coating sequence causes the dynamic repair layer (tetrasulfide bond) and optical control layer (liquid crystal) formed after the outer layer is cured to be physically covered by the inner layer, thus weakening the functional characteristics of Application Example 1.

[0209] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a high weather-resistant, high-definition lightbox advertising coating, characterized in that, Includes the following steps: (a) Preparation of outer coating: (a1) Weigh the following components: 65-70 parts by weight of polyurethane acrylate resin; 5-8 parts by weight of mercaptosiloxane compound; 8-12 parts by weight of multifunctional thiol crosslinking agent; 3-5 parts by weight of polymerizable liquid crystal monomer; (a2) Add to the solvent system: 75-85 parts by weight of propylene glycol methyl ether acetate; 25-30 parts by weight of propylene glycol phenyl ether; (a3) First mixing treatment; (a4) Add 0.5-1.0 parts by weight of ultraviolet absorber and 0.15 parts by weight of photoinitiator; (a5) Filtration and purification to obtain the finished outer coating; (b) Preparation of inner coating: (b1) Weigh the following components: 70-75 parts by weight of organosilicon acrylate resin; 10-15 parts by weight of bis(4-hydroxyphenyl) disulfide; 1.0 parts by weight of multifunctional acrylate crosslinking agent; (b2) Add to the solvent system: 70-80 parts by weight of propylene glycol methyl ether acetate; 25-35 parts by weight of propylene glycol tert-butyl ether; (b3) Add 0.1-0.3 parts by weight of a metal complex catalyst; (b4) Second mixing process to obtain the inner coating finished product.

2. The preparation method of the high weather-resistant and high-definition lightbox advertising coating according to claim 1, characterized in that, In (a1), the multifunctional thiol crosslinking agent is pentaerythritol tetrakis(3-mercaptopropionic acid) ester; the polymerizable liquid crystal monomer is 4,4-biphenyl di(6-acryloyloxyhexyl) ether.

3. The preparation method of the high weather-resistant and high-definition lightbox advertising coating according to claim 1, characterized in that, In (a4), the photoinitiator is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

4. The preparation method of the high weather-resistant and high-definition lightbox advertising coating according to claim 1, characterized in that, In (a3), the first mixing treatment is to stir at 400-600 rpm for 35-50 min at 40±2℃.

5. The preparation method of the high weather-resistant and high-definition lightbox advertising coating according to claim 1, characterized in that, In (b1), the organosilicon acrylate resin is a diacryloyloxy polysiloxane; the multifunctional acrylate crosslinking agent is trimethylolpropane triacrylate ethoxylate; and in (b3), the metal complexing catalyst is an organobismuth complex.

6. The method for preparing the high weather-resistant and high-definition lightbox advertising coating according to claim 1, characterized in that, In (b4), the second mixing treatment is ultrasonic dispersion at 35-50 kHz for 30-40 min.

7. A high weather-resistant and high-definition lightbox advertising coating comprises an outer coating and an inner coating prepared by the preparation method of the high weather-resistant and high-definition lightbox advertising coating as described in any one of claims 1-6.

8. A method for applying the high weather-resistant, high-definition lightbox advertising coating as described in claim 7, characterized in that, Includes the following steps: (c1) The surface of the lightbox substrate is coated with an inner layer of paint; (c2) Curing treatment; (c3) Apply an outer coating; (c4) Final curing heat treatment.

9. The application method of the high weather-resistant and high-definition lightbox advertising coating as described in claim 8, characterized in that, (c2) The curing treatment is heating at 80±2℃ for 10-20 min; (c4) The final curing heat treatment is irradiation with a light source wavelength of 50-400nm and a light intensity of 50-60mW / cm for 2-5 min, followed by heating at 55-65℃ for 10-20 min.

10. The application method of the high weather-resistant and high-definition lightbox advertising coating as described in claim 8, characterized in that, (c2) After curing, the thickness of the inner dry film is 35±1μm; (c4) After final curing, the thickness of the outer dry film is 20±1μm.

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