Low reflectance inks and methods of making

Abstract

This invention discloses a low-reflectivity ink and its preparation method, belonging to the field of printing ink technology. The low-reflectivity ink of this invention effectively solves the problem of existing inks' difficulty in simultaneously achieving low reflectivity, high adhesion, and high light-blocking performance by selecting polyester resin, adipic acid dihydrazide modifier, and molybdenum nitride-carbon black composite filler. The polyester resin, as the base resin, has good film-forming properties and compatibility; its active groups can undergo cross-linking reactions with adipic acid dihydrazide, improving the density and adhesion of the film layer. The nano-sized carbon black in the composite filler has excellent light absorption properties, effectively reducing ink reflectivity. Micron-sized molybdenum nitride, as the framework particle, enhances the mechanical strength and scratch resistance of the film layer, forming a complementary light-absorbing structure with the nano-sized carbon black, further improving light-blocking and mechanical properties, while also improving the ink's lightfastness and preventing coating deterioration after long-term use.

Description

Technical Field

[0001] This invention relates to the field of ink technology, and in particular to a low-reflectivity ink and its preparation method. Background Technology

[0002] In imaging devices, camera modules, and other equipment, low-reflectivity black ink is applied to the sides and edges of lenses to eliminate unwanted incident and reflected light and suppress glare and ghosting that degrade image quality. Similarly, in sensors, low-reflectivity coatings are applied around the laser source to suppress internal reflections. However, lens surfaces often require low-reflectivity coatings with low surface energy, posing a significant challenge to the adhesion of the ink film. Therefore, an ink with low reflectivity, high adhesion, and high light-blocking properties needs to be designed. Summary of the Invention

[0003] The main objective of this invention is to develop an ink with low reflectivity, high adhesion, high light-blocking performance, and scratch resistance, which can be well applied to optical devices.

[0004] To achieve the above objectives, the present invention proposes a low-reflectivity ink, wherein the raw materials of the low-reflectivity ink include polyester resin, a modifier, and composite filler; the modifier is adipic acid dihydrazide; the polymer monomers of the polyester resin include diacid, diol, and modifying monomer, wherein the modifying monomer includes tris(2-hydroxyethyl) isocyanurate; and the composite filler includes molybdenum nitride and carbon black.

[0005] In one embodiment, the low-reflectivity ink comprises the following raw materials in parts by weight: polyester resin: 40 to 50 parts; modifier: 3 to 6 parts; composite filler: 8 to 18 parts; catalyst: 0.5 to 1 part; additives: 2 to 5 parts; solvent: 5 to 15 parts.

[0006] In one embodiment, the polymerizable monomers of the polyester resin include a diacid, a diol, and a modifying monomer in a weight ratio of 40-50:35-45:3-6; wherein the diacid includes terephthalic acid and isophthalic acid in a weight ratio of 25-30:10-15; and / or, the diol includes 1,4-cyclohexanediethanol and ether diol in a weight ratio of 4-5:2-4.

[0007] In one embodiment, the glass transition temperature of the polyester resin is 45°C to 75°C.

[0008] In one embodiment, the hydroxyl value of the polyester resin is 34 mg KOH / g to 46 mg KOH / g.

[0009] In one embodiment, the weight-average molecular weight of the polyester resin is 10,000 to 30,000.

[0010] In one embodiment, the method for preparing the polyester resin includes the following steps: The monomer raw material of the polyester resin is added to a reaction vessel, heated to 200℃~210℃, and reacted for 2h~3h under nitrogen protection; then 0.2wt%~0.5wt% of esterification catalyst is added, the temperature is raised to 220℃~230℃ and vacuum is applied, and the reaction is carried out for 3h~5h. Then the temperature is lowered to 80℃~90℃, and triethanolamine is added to neutralize the residual acidity, thus completing the preparation of the polyester resin.

[0011] In one embodiment, the composite filler comprises nano-sized carbon black and micron-sized molybdenum nitride in a weight ratio of 5 to 8:1; wherein the nano-sized carbon black has a particle size of 20 nm to 50 nm; and the micron-sized molybdenum nitride has a particle size of 0.5 μm to 1 μm.

[0012] In one embodiment, the preparation process of the composite filler includes the following steps: Molybdenum nitride powder and carbon black powder were added to a dispersion vessel, and an appropriate amount of anhydrous ethanol was added to prepare a slurry with a solid content of about 50wt%~60wt%. Then, a titanate coupling agent of 1.5wt%~2.5wt% of the total mass of the powder was added and stirred for 30 minutes. After that, it was transferred to a horizontal sand mill and circulated for 1h~2h. Then, it was flash dried, ground and dispersed to complete the preparation of the composite filler.

[0013] In one embodiment, the catalyst includes at least one of dioctyltin diacetate, dibutyltin diacetate, triethylamine, dimethylethanolamine, and triethylenediamine.

[0014] The present invention also proposes a method for preparing the aforementioned low-reflectivity ink, the method comprising the following steps: S1. The polyester resin is preheated and dispersed in a solvent to obtain a first dispersion; the modifier is dispersed in the solution to obtain a modifier solution; S2. Add the additives and composite fillers to the first dispersion obtained in step S1, stir and disperse, then add the catalyst, stir and disperse, and then add the modifier solution dropwise while stirring to complete the preparation of the low reflectivity ink.

[0015] In one embodiment, in step S1, the concentration of the modifier solution is 20wt%~30wt%.

[0016] In one embodiment, in step S2, the dropping rate of the modifier solution is 1 ml / min to 2 ml / min.

[0017] In one embodiment, during step S2, the reaction time is 15 min to 20 min and the reaction temperature is 25 °C to 35 °C during the process of adding the modifier solution dropwise while stirring.

[0018] This invention's low-reflectivity ink effectively solves the problem of existing inks' inability to simultaneously achieve low reflectivity, high adhesion, and high opacity through the synergistic effect of polyester resin, adipic acid dihydrazide modifier, and molybdenum nitride-carbon black composite filler. Polyester resin, as the base resin, possesses excellent film-forming properties and compatibility. Its active groups in the molecular structure can undergo cross-linking reactions with adipic acid dihydrazide, enhancing the film's density and adhesion. The nano-sized carbon black in the composite filler exhibits excellent light absorption properties, effectively reducing ink reflectivity. Micron-sized molybdenum nitride, as the framework particle, enhances the film's mechanical strength and scratch resistance, forming a complementary light-absorbing structure with the nano-sized carbon black, further improving opacity and mechanical properties, while also improving the ink's lightfastness and preventing coating deterioration after long-term use. The preparation method of this invention's ink is simple and convenient. By using stepwise dispersion and controlling parameters such as reaction temperature and droplet rate, it ensures thorough mixing and complete reaction of all components, resulting in a stable ink with stable performance, suitable for large-scale production, and low production costs, demonstrating promising industrial application prospects. Detailed Implementation

[0019] 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 a part of the embodiments of the present invention, and not all of the 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.

[0020] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0021] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0022] The technical problem solved by this invention is as follows: In imaging devices, camera modules, and other instruments, low-reflectivity black ink is applied to the sides and edges of lenses to eliminate unwanted incident and reflected light and suppress glare and ghosting that degrade image quality; similarly, in sensors, low-reflectivity coatings are applied around the light source to suppress internal reflections from the laser. However, lens surfaces often require a low-reflectivity coating with low surface energy, posing a significant challenge to the adhesion of the ink film. Therefore, an ink with low reflectivity, high adhesion, and high light-blocking performance needs to be designed.

[0023] It should be noted that in related technologies, a low-reflection coating is formed by using a surface anti-reflective coating containing adhesive resin, carbon black, hydrophobically treated dry silica, coarse particles, dyes, and solvents for atomized coating; however, the coating has poor lightfastness, causing the low-reflection coating to deteriorate significantly over time; in another related technology, the adhesion between the ink film and the low-reflection coating or coating surface of the equipment is poor, and it is easy to peel off or fade.

[0024] To address the aforementioned technical problems, this invention proposes a low-reflectivity ink. The raw materials of the low-reflectivity ink include polyester resin, a modifier, and a composite filler. The modifier is adipic acid dihydrazide. The polymer monomers of the polyester resin include a diacid, a diol, and a modifying monomer, wherein the modifying monomer includes tris(2-hydroxyethyl) isocyanurate. The composite filler includes molybdenum nitride and carbon black.

[0025] Specifically, amorphous polyester was selected as the main film-forming material, copolymerized from diacids, diols, and modifying monomers. The trifunctional branched structure of the modifying monomers significantly improved the resin's heat resistance and cohesive strength while maintaining its amorphous nature. Adipate dihydrazide (ADH) was introduced as a modifier, which not only reacts with the active groups on the polyester segments to form a crosslinking network, but its terminal highly polar hydrazide groups can also form hydrogen bonds or coordination bonds with ions on the coating surface, especially the magnesium fluoride coating, effectively solving the problem of easy peeling caused by traditional inks relying solely on van der Waals forces for adhesion. A compound of molybdenum nitride and carbon black was used as a composite filler. Compared to single carbon black filler, carbon black provides full-band, high-efficiency light absorption, ensuring extremely low reflectivity and excellent light-shielding properties. Molybdenum nitride acts as an "anchor," with nano-sized carbon black adhering to it through treatment. This helps reduce the diffuse reflection of molybdenum nitride powder and improve its light absorption performance, forming a composite particle with complementary light absorption. Furthermore, after surface treatment with a coupling agent, molybdenum nitride can form a strong chemical bond with polyester resin and a tight mechanical and chemical bond with the coating surface. At the same time, its ceramic properties also improve the scratch resistance and abrasion resistance of the ink layer.

[0026] Furthermore, the low-reflectivity ink comprises the following raw materials in parts by weight: 40 to 50 parts polyester resin; 3 to 6 parts modifier; 8 to 18 parts composite filler; 0.5 to 1 part catalyst; 2 to 5 parts additives; and 5 to 15 parts solvent.

[0027] Further, the polymerizable monomers of the polyester resin include a diacid, a diol, and a modifying monomer in a weight ratio of 40~50:35~45:3~6; wherein the diacid includes terephthalic acid and isophthalic acid in a weight ratio of 25~30:10~15; and / or, the diol includes 1,4-cyclohexanediethanol and ether diol in a weight ratio of 4~5:2~4.

[0028] Furthermore, the ether diol includes at least one of diethylene glycol and triethylene glycol.

[0029] Furthermore, the glass transition temperature of the polyester resin is 45℃~75℃; and / or, the hydroxyl value of the polyester resin is 34mgKOH / g~46mgKOH / g; and / or, the weight-average molecular weight of the polyester resin is 10000~30000. Polyester resins with these performance parameters can form good compatibility with modifiers and composite fillers, while ensuring the flexibility and adhesion of the ink film and preventing film cracking.

[0030] Further, the preparation method of the polyester resin includes the following steps: adding the monomer raw material of the polyester resin into a reaction vessel, heating to 200℃~210℃, and reacting under nitrogen protection for 2h~3h; then adding 0.2wt%~0.5wt% of esterification catalyst, heating to 220℃~230℃ and evacuating, reacting for 3h~5h, then cooling to 80℃~90℃, adding triethanolamine to neutralize residual acidity, and completing the preparation of the polyester resin.

[0031] The polyester resin prepared by this method has high purity and stable performance. Its molecular structure contains a large number of active groups, which can undergo cross-linking reaction with the modifier adipate dihydrazide to improve the density and adhesion of the ink film.

[0032] Furthermore, the composite filler comprises nano-sized carbon black and micron-sized molybdenum nitride in a weight ratio of 5 to 8:1; wherein the particle size of the nano-sized carbon black is 20 nm to 50 nm; and the particle size of the micron-sized molybdenum nitride is 0.5 μm to 1 μm.

[0033] Nanoscale carbon black has excellent light absorption properties, which can effectively reduce the reflectivity of ink and improve the light-blocking performance. Micron-sized molybdenum nitride, as a framework particle, enhances the mechanical strength and scratch resistance of the film layer and forms a complementary light absorption structure with nanoscale carbon black, further optimizing the optical and mechanical properties of the film layer. The two work together to achieve a balance between low reflectivity and high light-blocking performance, while also improving the wear resistance and weather resistance of the film layer.

[0034] Furthermore, the preparation process of the composite filler includes the following steps: Molybdenum nitride powder and carbon black powder were added to a dispersion vessel, along with an appropriate amount of anhydrous ethanol, to prepare a slurry with a solid content of approximately 50wt%~60wt%. Then, a titanate coupling agent of 1.5wt%~2.5wt% of the total powder mass was added, and the mixture was stirred for 30 minutes. The mixture was then transferred to a horizontal sand mill and circulated for 1h~2h, followed by flash drying and further grinding to break up the particles, thus completing the preparation of the composite filler. The addition of the titanate coupling agent improves the compatibility between the composite filler and the polyester resin, prevents filler agglomeration, and ensures uniform dispersion of the filler in the ink, thereby guaranteeing the stability of the ink's performance. The circulating grinding in the horizontal sand mill further refines the filler particle size, improving the filler's dispersibility and light absorption effect.

[0035] Furthermore, the catalyst includes at least one of dioctyltin diacetate, dibutyltin diacetate, triethylamine, dimethylethanolamine, and triethylenediamine. The catalyst can promote the crosslinking reaction between the polyester resin and the modifier, accelerate the reaction rate, and increase the degree of crosslinking, thereby enhancing the density and adhesion of the ink film.

[0036] Furthermore, the additives include at least one of a dispersant, a defoamer, and a leveling agent; wherein the dispersant can be a polycarboxylate dispersant, the defoamer can be an organosilicon defoamer, and the leveling agent can be an acrylate leveling agent. The dispersant can further improve the dispersion stability of the composite filler in the ink and prevent agglomeration; the defoamer can eliminate bubbles generated during ink preparation and prevent defects such as pinholes and bubbles in the film layer; the leveling agent can improve the leveling performance of the ink, ensuring a smooth and even film layer and improving optical performance.

[0037] Furthermore, the solvent includes at least one of ethyl acetate, butyl acetate, and propylene glycol methyl ether acetate. This type of solvent has good solubility for polyester resins, modifiers, and composite fillers, ensuring uniform mixing of the ink components. Simultaneously, the solvent evaporation rate is moderate, preventing defects such as sagging and edge shrinkage in the film layer.

[0038] The present invention also provides a method for preparing the above-mentioned low-reflectivity ink, comprising the following steps: S1. The polyester resin is preheated and dispersed in a solvent to obtain a first dispersion; the modifier is dispersed in the solution to obtain a modifier solution; S2. Add the additives and composite fillers to the first dispersion obtained in step S1, stir and disperse, then add the catalyst, stir and disperse, and then add the modifier solution dropwise while stirring to complete the preparation of the low reflectivity ink.

[0039] Further, in step S1, the preheating temperature of the polyester resin is 60℃~80℃, and the preheating time is 30min~60min. After preheating, it is dispersed in the solvent by high-speed stirring at a speed of 1000r / min~1500r / min for 30min~60min to ensure that the polyester resin is completely dissolved and dispersed to form a uniform first dispersion. The solvent of the modifier solution is the same as that in step S1, and the concentration of the modifier solution is 20wt%~30wt%. The modifier is completely dissolved by low-speed stirring at a speed of 300r / min~500r / min for 15min~30min.

[0040] Further, in step S2, after adding the additives and composite fillers, dispersion is carried out using a combination of high-speed stirring and ultrasonic dispersion. The high-speed stirring speed is 1500 r / min to 2000 r / min, the ultrasonic dispersion power is 300 W to 500 W, and the dispersion time is 60 min to 90 min, ensuring that the additives and composite fillers are uniformly dispersed in the first dispersion and avoiding agglomeration. After adding the catalyst, the stirring speed is adjusted to 800 r / min to 1000 r / min, and the stirring time is 15 min to 20 min, so that the catalyst is uniformly dispersed. The dropping rate of the modifier solution is 1 ml / min to 2 ml / min. During the process of adding the solution while stirring, the reaction time is 15 min to 20 min, and the reaction temperature is 25℃ to 35℃. After the addition is completed, stirring continues for 20 min to 30 min to ensure that the polyester resin and the modifier fully crosslink and react to form a uniform and stable low-reflectivity ink.

[0041] The technical solution of the present invention will be further described below through specific embodiments.

[0042] Example 1 The raw materials of the low-reflectivity ink in Example 1 are as follows, by weight: Polyester resin: 40 parts; adipate dihydrazide: 3 parts; composite filler: 8 parts; catalyst: dibutyltin diacetate: 0.5 parts; dispersant: 1 part; defoamer: 0.5 parts; leveling agent: 0.5 parts; solvent: 5 parts.

[0043] The raw materials for the reactant monomers of polyester resin include terephthalic acid, isophthalic acid, 1,4-cyclohexanediol, triethylene glycol and tris(2-hydroxyethyl) isocyanurate in a weight ratio of 30:15:20:15:3.

[0044] The preparation process of polyester resin includes the following steps: The reactant monomer was added to the reactor and heated to 210°C. The reaction was carried out for 3 hours under nitrogen protection. Then, 0.2 wt% of tetrabutyl titanate was added, the temperature was raised to 220°C and the vacuum was drawn to (-0.09) MPa. The reaction was carried out for 5 hours. Then, the temperature was lowered to 80°C and triethanolamine was added for neutralization to complete the preparation of polyester resin.

[0045] The glass transition temperature of the polyester resin was measured to be 45℃, the hydroxyl value was 34mgKOH / g, and the weight-average molecular weight was 14000.

[0046] The preparation process of composite fillers includes the following steps: Micron-sized molybdenum nitride (average particle size 0.5μm~1μm) and nano-sized carbon black (average particle size 30nm) in a weight ratio of 1:6 were added to a dispersion vessel, and an appropriate amount of anhydrous ethanol was added to prepare a slurry with a solid content of 50wt%. Then, titanate coupling agent accounting for 1.5wt% of the total powder mass was added, and the mixture was stirred for 30min. After that, it was transferred to a horizontal sand mill and circulated for 2h. Then, it was flash dried, ground and dispersed to obtain the composite filler.

[0047] The method for preparing the low-reflectivity ink in Example 1 includes the following steps: S1. Preheat the polyester resin to 60°C for 30 minutes, then disperse it in the solvent at 1000 r / min and stir for 60 minutes to obtain the first dispersion; disperse the modifier adipic acid dihydrazide in the same solvent and stir at 300 r / min for 30 minutes to prepare a 20 wt% modifier solution. S2. Add the additives and composite fillers to the first dispersion, stir at a high speed of 1500 r / min, and simultaneously ultrasonically disperse at 300 W for 90 min. Then add the catalyst, stir at 800 r / min for 20 min, and then add the modifier solution dropwise at a dropping rate of 1 ml / min while stirring. Control the reaction temperature at 25℃ and react for 20 min. After the addition is complete, continue stirring for 30 min to obtain the low reflectivity ink.

[0048] The low-reflectivity ink from Example 1 was coated onto a glass surface with a magnesium fluoride film and cured at 120°C for 20 minutes to form a film with a thickness of approximately 0.5 mm. The reflectivity, adhesion, OD value, reflectivity change rate after UV aging, and damp heat resistance of the film were measured.

[0049] After testing, the film formed by the low-reflectivity ink in Example 1 had a reflectivity of 1.5%, an adhesion of 5B, an OD value of 3.1, a reflectivity of 3.2% after 1000 hours of UV aging, and no peeling or discoloration after damp heat resistance testing. All performance characteristics met the requirements.

[0050] Example 2 The raw materials for the low-reflectivity ink in Example 2, by weight, are: Polyester resin: 45 parts; adipate dihydrazide: 5 parts; composite filler: 13 parts; catalyst is dibutyltin diacetate and triethylamine in a weight ratio of 1:1: 0.5 parts; dispersant: 1.5 parts; defoamer: 1 part; leveling agent: 1 part; solvent: 10 parts.

[0051] The raw materials for the polyester resin include terephthalic acid, isophthalic acid, 1,4-cyclohexanediol, triethylene glycol and tris(2-hydroxyethyl) isocyanurate in a weight ratio of 27.5:12.5:24:16:5.

[0052] The preparation process of the polyester resin in Example 2 is the same as that in Example 1.

[0053] The glass transition temperature of the polyester resin was measured to be 60℃, the hydroxyl value was 40mgKOH / g, and the weight-average molecular weight was 20000.

[0054] The preparation process of composite fillers includes the following steps: Micron-sized molybdenum nitride (average particle size 0.5μm~1μm) and nano-sized carbon black (average particle size 30nm) in a weight ratio of 1:5 were added to a dispersion vessel, and an appropriate amount of anhydrous ethanol was added to prepare a slurry with a solid content of 50wt%. Then, titanate coupling agent accounting for 2.5wt% of the total powder mass was added, and the mixture was stirred for 30min. After that, it was transferred to a horizontal sand mill and circulated for 1h. Then, it was flash dried, ground and dispersed to obtain the composite filler.

[0055] The method for preparing the low-reflectivity ink in Example 2 includes the following steps: S1. Preheat the polyester resin to 70°C for 45 min, then disperse it in the solvent at 1250 r / min and stir for 45 min to obtain the first dispersion; disperse the modifier adipic acid dihydrazide in the same solvent and stir at 400 r / min for 22 min to prepare a 25 wt% modifier solution. S2. Add the additives and composite fillers to the first dispersion, stir at a high speed of 1750 r / min, and simultaneously ultrasonically disperse at 400 W for 75 min. Then add the catalyst, stir at 900 r / min for 17 min, and then add the modifier solution dropwise at a dropping rate of 1.5 ml / min while stirring. Control the reaction temperature at 30℃ and react for 17 min. After the addition is complete, continue stirring for 25 min to obtain the low reflectivity ink.

[0056] The low-reflectivity ink from Example 2 was coated onto a glass surface with a magnesium fluoride film and cured at 120°C for 20 minutes to form a film with a thickness of approximately 0.5 mm. The reflectivity, adhesion, OD value, reflectivity change rate after UV aging, and damp heat resistance of the film were measured.

[0057] After testing, the film formed by the low-reflectivity ink in Example 2 had a reflectivity of 2.1%, an adhesion of 5B, an OD value of 3.2, a reflectivity of 3.8% after UV aging, and no peeling or discoloration after the damp heat resistance test. All performance characteristics met the requirements.

[0058] Example 3 The raw materials for the low-reflectivity ink in Example 3, by weight, are: Polyester resin: 50 parts; adipate dihydrazide: 5 parts; composite filler: 18 parts; catalyst: triethylenediamine: 1 part; dispersant: 2 parts; defoamer: 1 part; leveling agent: 1 part; solvent: 10 parts.

[0059] The raw materials for polyester resin include terephthalic acid, isophthalic acid, 1,4-cyclohexanediol, triethylene glycol, and tris(2-hydroxyethyl) isocyanurate in a weight ratio of 30:15:25:20:6.

[0060] The preparation process of the polyester resin in Example 3 is the same as that in Example 1.

[0061] The glass transition temperature of the polyester resin was measured to be 70℃, the hydroxyl value was 42mgKOH / g, and the weight-average molecular weight was approximately 30,000.

[0062] The composite filler in Example 3 is the same as in Example 2.

[0063] The method for preparing the low-reflectivity ink in Example 3 includes the following steps: S1. Preheat the polyester resin to 80°C for 60 min, then disperse it in the solvent at 1500 r / min and stir for 30 min to obtain the first dispersion; disperse the modifier adipic acid dihydrazide in the same solvent and stir at 500 r / min for 15 min to prepare a 30 wt% modifier solution. S2. Add the additives and composite fillers to the first dispersion, stir at a high speed of 2000 r / min, and simultaneously ultrasonically disperse at a power of 500 W for 60 min. Then add the catalyst, stir at a speed of 1000 r / min for 15 min, and then add the modifier solution dropwise at a dropping rate of 2 ml / min while stirring. Control the reaction temperature at 35℃ and react for 15 min. After the addition is complete, continue stirring for 20 min to obtain the low reflectivity ink.

[0064] The low-reflectivity ink from Example 3 was coated onto a glass surface with a magnesium fluoride film and cured at 120°C for 20 minutes to form a film with a thickness of approximately 0.5 mm. The reflectivity, adhesion, OD value, reflectivity change rate after UV aging, and damp heat resistance of the film were measured.

[0065] After testing, the film formed by the low-reflectivity ink in Example 3 had a reflectivity of 2.3%, an adhesion of 5B, an OD value of 3.2, a reflectivity of 4.6% after UV aging, and no peeling or discoloration after damp heat resistance testing. All performance characteristics met the requirements.

[0066] Comparative Example 1 Comparative Example 1 is based on Example 1, except that the ink in Comparative Example 1 does not contain the modifier adipate dihydrazide during the preparation process.

[0067] The low-reflectivity ink from Comparative Example 1 was coated onto a glass surface with a magnesium fluoride film and cured at 120°C for 20 minutes to form a film with a thickness of approximately 0.5 mm. The reflectivity, adhesion, OD value, reflectivity change rate after UV aging, and damp heat resistance of the film were measured.

[0068] After testing, the film formed by the low-reflectivity ink in Comparative Example 1 had a reflectivity of 4.1%, an adhesion of 3B, an OD value of 3.1, a reflectivity of 8.9% after UV aging, and slight peeling after the damp heat resistance test.

[0069] Comparative Example 2 Comparative Example 2 is based on Example 1, except that the composite filler in the ink of Comparative Example 2 is only nano-sized carbon black.

[0070] The low-reflectivity ink from Comparative Example 2 was coated onto a glass surface with a magnesium fluoride film and cured at 120°C for 20 minutes to form a film with a thickness of approximately 0.5 mm. The reflectivity, adhesion, OD value, reflectivity change rate after UV aging, and damp heat resistance of the film were measured.

[0071] After testing, the film formed by the low-reflectivity ink in Comparative Example 2 had a reflectivity of 4.4%, an adhesion of 4B, an OD value of 2.9, a reflectivity of 10.4% after UV aging, and no obvious peeling after the damp heat resistance test, but the ink layer color became lighter.

[0072] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A low-reflectivity ink, characterized in that, The raw materials for the low-reflectivity ink include polyester resin, modifier, and composite filler; The modifier is adipic acid dihydrazide; The polymer monomers of the polyester resin include diacids, diols and modifying monomers, wherein the modifying monomers include tris(2-hydroxyethyl) isocyanurate. The composite filler includes molybdenum nitride and carbon black.

2. The low-reflectivity ink as described in claim 1, characterized in that, The low-reflectivity ink comprises the following raw materials in parts by weight: Polyester resin: 40-50 parts; Modifier: 3 to 6 parts; Composite filler: 8 to 18 parts; Catalyst: 0.5 to 1 part; Additives: 2 to 5 parts; Solvent: 5 to 15 parts.

3. The low-reflectivity ink as described in claim 1, characterized in that, The polymer monomers of the polyester resin include a dibasic acid, a diol, and a modifying monomer in a weight ratio of 40~50:35~45:3~6; Wherein, the dicarboxylic acid comprises terephthalic acid and isophthalic acid in a weight ratio of 25~30:10~15; and / or, the diol comprises 1,4-cyclohexanediethanol and ether diol in a weight ratio of 4~5:2~4.

4. The low-reflectivity ink as described in claim 1, characterized in that, The glass transition temperature of the polyester resin is 45℃~75℃; And / or, the hydroxyl value of the polyester resin is 34 mg KOH / g to 46 mg KOH / g; And / or, the weight-average molecular weight of the polyester resin is 10,000 to 30,000.

5. The low-reflectivity ink as described in claim 1, characterized in that, The method for preparing the polyester resin includes the following steps: The monomer raw material of the polyester resin is added to a reaction vessel, heated to 200℃~210℃, and reacted for 2h~3h under nitrogen protection; then 0.2wt%~0.5wt% of esterification catalyst is added, the temperature is raised to 220℃~230℃ and vacuum is applied, and the reaction is carried out for 3h~5h. Then the temperature is lowered to 80℃~90℃, and triethanolamine is added for neutralization to complete the preparation of the polyester resin.

6. The low-reflectivity ink as described in claim 1, characterized in that, The composite filler comprises nano-sized carbon black and micron-sized molybdenum nitride in a weight ratio of 5 to 8:

1. The nano-sized carbon black has a particle size of 20 nm to 50 nm; the micron-sized molybdenum nitride has a particle size of 0.5 μm to 1 μm.

7. The low-reflectivity ink as described in claim 1, characterized in that, The preparation process of the composite filler includes the following steps: Molybdenum nitride powder and carbon black powder were added to a dispersion vessel, and an appropriate amount of anhydrous ethanol was added to prepare a slurry with a solid content of 50wt%~60wt%. Then, a titanate coupling agent accounting for 1.5wt%~2.5wt% of the total powder mass was added, and the mixture was stirred for 30 minutes. After that, it was transferred to a horizontal sand mill and circulated for 1h~2h. Then, it was flash dried, ground and dispersed to complete the preparation of the composite filler.

8. The low-reflectivity ink as described in claim 2, characterized in that, The catalyst includes at least one of dioctyltin diacetate, dibutyltin diacetate, triethylamine, dimethylethanolamine, and triethylenediamine.

9. A method for preparing a low-reflectivity ink as described in any one of claims 1 to 8, characterized in that, The method for preparing the low-reflectivity ink includes the following steps: S1. Preheat the polyester resin and disperse it in a solvent to obtain a first dispersion; disperse the modifier in the solution to obtain a modifier solution; S2. Add the additives and composite fillers to the first dispersion obtained in step S1, stir and disperse, then add the catalyst, stir and disperse, and then add the modifier solution dropwise while stirring to complete the preparation of the low reflectivity ink.

10. The method for preparing low-reflectivity ink as described in claim 9, characterized in that, In step S1, the concentration of the modifier solution is 20wt%~30wt%; And / or, in step S2, during the process of adding the modifier solution dropwise while stirring, the reaction time is 15 min to 20 min and the reaction temperature is 25℃ to 35℃.