Preparation method and application of micronized stable UV insulating jet ink

Abstract

The invention discloses a preparation method and application of micronized stable UV insulating ink jet, and relates to the technical field of UV insulating ink jet preparation, low molecular weight hyperbranched modified acrylic resin, an acrylate monomer, a UV auxiliary agent and self-made color paste are mixed and stirred uniformly, and the sprayable UV insulating ink jet is obtained. The invention relates to a UV (ultraviolet) coating which is characterized by comprising the following components in parts by weight: 20-40 parts of low-molecular-weight hyperbranched modified acrylic resin, 50-70 parts of acrylate monomer, 2-10 parts of UV aid and 1-7 parts of self-made color paste. According to the invention, various modified acrylate resins and acrylate monomers with different degrees of functionality are fused, and the efficient UV auxiliary agent and the self-made color paste are matched, so that the dynamic adjustment of the ink jet formula is realized. According to the customized scheme, the functional characteristics of insulating ink jet can be accurately regulated and controlled according to specific application requirements, and the use scene is widened.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of UV insulating inkjet, and specifically provides a method for preparing a micronized and stable UV insulating inkjet and its application. Background Art

[0002] In the rapidly developing new energy vehicle field, ensuring the absolute safety of the battery system is the cornerstone for driving the industry forward. With the changes led by technological iteration, electric vehicles with an 800V high-voltage platform have become the trend of the new era, which poses unprecedented high standards for the insulating coating of the battery's core component - the battery cell. Facing this challenge, the traditional blue film technology gradually reveals its limitations, such as complex processes, high costs, and poor environmental adaptability.

[0003] Therefore, the present invention provides a method for preparing a micronized and stable UV insulating inkjet for new energy vehicles and its application, which provides a micronized, low-viscosity, and long-term stable UV insulating inkjet. By integrating various modified acrylate resins, acrylate monomers with different functional groups, high-efficiency UV additives, and self-made color pastes, and precisely adjusting the components and ratios, the customization of the functions of the UV insulating inkjet is achieved to meet different application requirements. This formulation is designed specifically for the battery cells of 800V new energy vehicles and has the characteristics of water-boiling resistance, acid and alkali resistance, electrolyte resistance, impact resistance, salt spray resistance, high adhesion, high shear resistance, high insulation, and rapid curing, making up for the shortcomings of the existing technology and providing a safer, more reliable, efficient, durable, and cost-optimized solution for the new energy vehicle industry.

[0004] In addition, in order to pursue higher clarity and precision, we selected a nozzle with a diameter of 450nm to perform the coating spraying operation. If the particle size is too large, it will not only cause nozzle clogging problems but also result in unnecessary equipment cost losses. The existing UV insulating inkjet products on the market face bottlenecks: either the particle size is difficult to reduce below 300nm, or the small particle size state cannot be continuously maintained under the condition of 60°C high temperature. Therefore, we propose a method for preparing a micronized and stable UV insulating inkjet and its application. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing a micronized and stable UV insulating inkjet and its application to solve the problems raised in the above background art.

[0006] To achieve the above object, the present invention provides the following technical solutions: A preparation method and application of a micronized stable UV insulating inkjet. This inkjet is prepared by carefully selecting and scientifically proportioning various modified acrylate resins, mono-functional, di-functional, tri-functional, tetra-functional and hexa-functional acrylate monomers, supplemented with color pastes and various high-efficiency UV additives. After undergoing rigorous extreme condition tests, it exhibits excellent insulating properties and adhesion. The technical solutions of the present invention are mainly based on the following innovations:

[0007] First of all, the addition of modified acrylate resin, as the core component of the present invention, provides excellent comprehensive properties for the coating by virtue of its unique molecular structure and chemical characteristics. Specifically:

[0008] Adding medium and low molecular weight hyperbranched acrylate polyurethane can significantly improve the curing speed of the UV insulating coating. Due to its low viscosity characteristics, it is particularly suitable for the inkjet process. First of all, due to the low molecular weight design, this PUA has more active groups, such as double bonds, which can quickly react with photoinitiators under ultraviolet light irradiation to form a dense network structure, thus accelerating the curing of the coating. Secondly, the hyperbranched structure is the key factor to improve the curing rate and reduce the viscosity. Hyperbranched polymers reduce the entanglement between molecules due to their highly branched molecular chains, which enables the reactants to more easily contact and react with each other. At the same time, due to the increase in intermolecular voids, the fluidity is enhanced, so it exhibits a lower viscosity. In the inkjet process, low viscosity is particularly important because it ensures that the inkjet can smoothly pass through the nozzle of the inkjet device to form a uniform and delicate coating, and reduces the occurrence of bubbles and defects. In addition, low viscosity also helps the inkjet to better spread on the surface of the substrate during the spraying process, enhancing the adhesion and flatness of the coating. Therefore, adding low molecular weight hyperbranched acrylate polyurethane to the UV insulating coating not only improves the curing speed, but also enhances its applicability in inkjet applications, providing a better coating solution for fields such as new energy vehicles.

[0009] Adding anhydride-modified epoxy acrylate can significantly improve the acid and alkali resistance and electrolyte resistance of the UV insulating coating. This may be because under the action of anhydride modification, the crosslinking density between epoxy acrylate molecules increases, forming a more stable three-dimensional network structure. This enhanced crosslinked structure reduces the permeability of the coating to acids, alkalis and electrolytes, thereby enhancing the chemical stability and corrosion resistance of the coating, making it better protect the substrate in a corrosive environment. In addition, anhydride modification may also introduce functional groups with higher polarity and reactivity, further enhancing the chemical resistance of the coating.

[0010] Acrylate polyurethane with polyether polyol added as the main chain can greatly enhance the impact resistance and toughness of the coating. Polyether polyol-based polyurethane, due to its excellent flexibility and wear resistance, not only maintains good insulation performance after being added to the UV-curable coating, but also increases the elasticity and crack resistance of the coating, effectively absorbing and dispersing external force impacts and reducing the risk of damage to battery cells. The coating formed in this way cures rapidly under ultraviolet light irradiation, providing a protective film that is both tough and resistant to external mechanical stress, offering comprehensive protection for battery cells.

[0011] Adding acrylate polyurethane oligomers chain-extended with small molecular weight diols can improve the electrical properties of the coating by optimizing its microstructure. The small molecular weight diols as chain extenders contribute to the formation of the polyurethane network, resulting in a coating with a lower dielectric constant and dielectric loss, while also enhancing the thermal stability and mechanical strength of the coating. The optimized coating cures rapidly under UV light initiation, and the formed film has excellent insulation properties, effectively preventing current leakage, thus improving the overall electrical performance and ensuring the safe operation of battery cells or circuits.

[0012] Secondly, utilize the complementary advantages of multifunctional monomers: Acrylate monomers with different functionalities play unique roles during the UV curing process to achieve complementary advantages. Among them, monofunctional acrylate monomers endow the coating with good flexibility and fluidity, ensuring uniform coverage and close adhesion to the substrate; while hexa-functional acrylate monomers significantly increase the crosslinking density and hardness of the coating, thereby enhancing the wear resistance and chemical resistance of the coating. The reasonable combination of the above monomers enables the coating to possess both flexibility and rigidity, as well as excellent durability.

[0013] Again, in the self-made color paste, phthalocyanine blue is carefully selected as the core blue color powder in the color paste, and it is skillfully combined with other key components - aldehyde-ketone resin A81, acrylate polyurethane with polyether polyol as the main chain (specially synthesized with PPG600), benzyl acrylate, titanium dioxide, and highly efficient wetting and dispersing agents. Due to its excellent wetting performance and abundant aldehyde and ketone functional groups, aldehyde-ketone resin A81 forms stable coordination bonds with the N atoms in the phthalocyanine blue molecules, effectively inhibiting the aggregation of phthalocyanine blue molecules. At the same time, the unique cage-like structure of the polyether polyol acrylate polyurethane synthesized based on PPG600 can tightly wrap the phthalocyanine blue particles, avoiding the mutual collision and aggregation between the particles, and significantly improving the stability of the color powder in the ink. This discovery not only optimizes the ink formula but also further verifies the unique advantages of PPG600 in synthesizing high-performance acrylate polyurethane. The introduction of benzyl acrylate utilizes the similarity of its benzene ring structure to the phthalocyanine blue molecules to promote the uniform dispersion of the color powder particles and enhance the color performance and stability of the ink. The addition of inorganic powder not only provides a solid support for the coating but also further improves the insulating electrical properties of the ink. In addition, due to the amphiphilic nature of the wetting and dispersing agent, it can build a bridge between the phthalocyanine blue molecules and the non-polar molecules of the ink, promoting the good combination of the color powder and the ink matrix. The synergistic effect of these components jointly constructs a stable and efficient ink system, enabling the color powder particles to remain stably dispersed at 60°C and meeting the stringent requirements of high-precision inkjet printing in the long term.

[0014] In addition, UV additives play an indispensable role in the present invention. As the starting substances for the curing reaction, the type and dosage of photoinitiators are directly related to the curing rate and degree of the coating; additives such as leveling agents and defoaming agents help improve the construction performance of the inkjet and the quality of the coating surface; antioxidants, ultraviolet absorbers, etc. can effectively extend the coating life and prevent damage caused by the external environment. Through reasonable selection and proportioning of the above additives, their synergistic effect is fully exerted, greatly improving the overall performance of the coating.

[0015] Finally, scientific formulation design and precise process control are also one of the core technologies of the present invention. By studying the interaction mechanism among the components and combining advanced formulation design and process regulation means, the proportion and addition sequence of each component can be accurately controlled to optimize the inkjet composition and performance. At the same time, strictly control the process parameters such as temperature, humidity, and stirring rate during the production process to ensure the stability and consistency of the inkjet quality. This scientific formulation design and process control strategy provide strong technical support for the preparation of high-performance and highly reliable UV insulating inkjet.

[0016] In summary, the present invention precisely formulates a modified acrylate resin, various functional acrylate monomers, and a variety of UV additives, supplemented by scientific formula design and process control, and finally obtains a low-viscosity UV inkjet that can simultaneously meet the requirements of water boiling resistance, acid and alkali resistance, electrolyte resistance, impact resistance, salt spray resistance, high adhesion, high shear resistance, high insulation, fast curing, and suitability for inkjet printing. Based on this, the present invention is completed.

[0017] The low molecular weight hyperbranched modified acrylic resin includes low molecular weight hyperbranched acrylate polyurethane, anhydride-modified epoxy acrylate, acrylate polyurethane with a polyether polyol main chain, and acrylate polyurethane oligomer extended by a small molecular weight polyol.

[0018] The low molecular weight hyperbranched acrylate polyurethane is obtained by the hydroxyl addition capping of diisocyanate with a "core molecule" and a hydroxyl-containing acrylate monomer respectively under the action of catalyst I.

[0019] The anhydride-modified epoxy acrylate is obtained by the addition polymerization reaction of glycidyl methacrylate with an anhydride under the action of catalyst II.

[0020] The acrylate polyurethane with a polyether polyol main chain is obtained by the hydroxyl addition capping of diisocyanate with a polyether polyol and a hydroxyl-containing acrylate monomer respectively under the action of catalyst I.

[0021] The acrylate polyurethane oligomer extended by a small molecular weight polyol is obtained by the hydroxyl addition capping of diisocyanate with a small molecular weight polyol and a hydroxyl-containing acrylate monomer respectively under the action of catalyst I.

[0022] The self-made color paste is obtained by uniformly mixing a blue pigment, an inorganic filler, a grinding resin, an acrylate monomer, and a wetting and dispersing agent.

[0023] Further, the preparation method of the low molecular weight hyperbranched acrylate polyurethane is as follows:

[0024] Place diisocyanate, a polymerization inhibitor, and catalyst I in a three-necked flask, stir evenly, and heat up to 40 - 70 °C. Slowly dropwise add the "core molecule" completely dissolved in tetrahydrofuran in advance. Heat up to 65 - 85 °C and maintain the temperature for reaction for 3 - 5 hours until the residual -NCO in the product reaches the theoretical -NCO to obtain polyurethane intermediate I.

[0025] Heat up polyurethane intermediate I to 60 - 80 °C, slowly dropwise add the hydroxyl-containing acrylate capping agent, control the temperature at 80 - 100 °C, and continue the reaction until the residual -NCO in the product is less than 5‰, then close the reaction to obtain the low molecular weight hyperbranched acrylate polyurethane.

[0026] Preferably, the diisocyanate is selected from at least one of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and hexamethylene diisocyanate. The preferred types of diisocyanates described in the text should be consistent with the previous part to ensure the consistency of material properties and the synergistic effect among patent examples.

[0027] Preferably, the polymerization inhibitor is selected from at least one of p-methoxyphenol, polymerization inhibitor 510, polymerization inhibitor ST-1, methylhydroquinone, butylhydroquinone, tert-butylcatechol, and 2,6-di-tert-butyl-p-cresol. The preferred types of polymerization inhibitors described in the text should be consistent with the previous part to ensure the consistency of material properties and the synergistic effect among patent examples.

[0028] Preferably, the catalyst I is selected from at least one of dibutyltin dilaurate, dibutyltin diacetate, dioctyltin diacetate, dibutyltin oxide, dibutyltin octoate, zinc diacetate, zinc laurate, zinc caprylate, bismuth neodecanoate, and bismuth isooctanoate. The preferred types of catalyst I described in the text should be consistent with the previous part to ensure the consistency of material properties and the synergistic effect among patent examples.

[0029] Preferably, the core molecule is selected from at least one of pentaerythritol and dipentaerythritol.

[0030] Preferably, the hydroxyl-containing acrylate capping agent is selected from at least one of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, and pentaerythritol triacrylate. The preferred types of hydroxyl-containing acrylate capping agents described in the text should be consistent with the previous part to ensure the consistency of material properties and the synergistic effect among patent examples.

[0031] Furthermore, the preparation method of the anhydride-modified epoxy acrylate is as follows:

[0032] Mix the liquid anhydride or the solid anhydride dissolved in the acrylate diluent monomer with the catalyst II and the polymerization inhibitor, heat the mixture to 60 - 80 °C, slowly dropwise add glycidyl methacrylate, and after the addition is completed, raise the temperature to 80 - 100 °C for reaction. When the epoxy ester of the product is less than 1 mol / kg and the acid value is less than 2 mg KOH / g, the anhydride-modified epoxy acrylate is obtained.

[0033] Preferably, the anhydride is selected from at least one of phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, and tetrahydrophthalic anhydride.

[0034] Preferably, the catalyst II is selected from at least one of benzyltriethylammonium chloride, trioctylmethylammonium chloride, tetraethylammonium bromide, tetrabutylammonium bromide, tetraamylammonium bromide, and triphenylphosphine, and more preferably at least one of tetrabutylammonium bromide and triphenylphosphine.

[0035] Furthermore, the preparation method of the acrylate polyurethane with a polyether polyol as the main chain is as follows:

[0036] Heat the polyether polyol to 110 °C, under the condition of ensuring the container is sealed, evacuate to a negative pressure of 0.2 MPa, and maintain for 1 hour. After the water removal operation is completed, set aside for later use. Heat the diisocyanate to 50 - 70 °C, and slowly dropwise add the catalyst I and the polyether polyol that has undergone water treatment. Heat to 50 - 70 °C, maintain the temperature and react for 3 - 5 hours until the residual -NCO in the product reaches the theoretical -NCO, obtaining polyurethane intermediate I.

[0037] After dropping the catalyst I into the polyurethane intermediate I, raise the temperature to 80 - 100 °C, add the acrylate capping agent containing hydroxyl groups, and continue the reaction until the residual -NCO in the product is less than 5‰, then stop the reaction, and the acrylate polyurethane with a polyether polyol as the main chain is obtained.

[0038] Preferably, the polyether polyol is selected from polypropylene glycol (PPG) and polyethylene glycol (PEG), specifically at least one of PPG200, PPG400, PPG600, PEG200, PEG300, PEG400, and PEG600.

[0039] Furthermore, the preparation method of the acrylate polyurethane oligomer extended by a low - molecular - weight polyol is as follows:

[0040] Mix the acrylate capping agent containing hydroxyl groups, chain extender, polymerization inhibitor, and catalyst I evenly, then raise the temperature to 50 - 70 °C, slowly dropwise add the diisocyanate, raise the temperature to 80 - 110 °C, and react until the residual -NCO in the product is less than 5‰, then stop the reaction, and the acrylate polyurethane oligomer extended by a low - molecular - weight polyol is obtained.

[0041] Preferably, the chain extender is selected from at least one of ethylene glycol, propylene glycol, 1,4 - butanediol, 2 - methyl - 1,3 - propanediol, diethylene glycol, 1,6 - hexanediol, trimethylolpropane, and glycerol.

[0042] Further, the acrylate monomer is selected from at least one of tetrahydrofurfuryl acrylate, isobornyl acrylate, 2-ethylhexyl acrylate, glycidyl methacrylate, lauryl acrylate, stearyl acrylate, benzyl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, ethoxyethoxyethyl acrylate, β-carboxyethyl acrylate, 1,6-hexanediol diacrylate, trimethylolcyclohexyl acrylate, dipentaerythritol hexaacrylate, propoxylated glycerol triacrylate, dicyclopentenyl acrylate, 2-methylbutyl acrylate, tris(2-hydroxyethyl) isocyanurate triacrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, ethoxylated pentaerythritol tetraacrylate, propoxylated neopentyl glycol diacrylate, ethylene glycol dimethacrylate, 2-phenoxyethyl acrylate, polyethylene glycol o-phenylphenyl ether acrylate, ethoxylated trimethylolpropane triacrylate, and acryloylmorpholine.

[0043] Further, the UV auxiliary is selected from at least one of a photoinitiator, a leveling agent, an antifoaming agent, or an adhesion promoter.

[0044] Preferably, the photoinitiator is selected from at least one of diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide, ethyl 2,4,6-trimethylbenzoyl phenylphosphinate, 1-hydroxycyclohexyl phenyl ketone, and 2-isopropylthioxanthone.

[0045] Preferably, the leveling agent is selected from at least one of BYK333, BYK346, BYK077, BYK358N (BYK Chemie Germany), TEGOGlide 425, TEGO Flow 300, and TEGO Glide100 (Evonik Degussa).

[0046] Preferably, the antifoaming agent is selected from at least one of TEGO Airex 920, TEGO Airex 900 (Evonik Degussa), BYK-020, BYK-085 (BYK Chemie Germany), and Lencolo 2108 (Lancolor).

[0047] Preferably, the adhesion promoter is selected from at least one of Sipomer PAM-100 (Solvay), LTH (Evonik Degussa), SYG-PM-2 (Xinghengtai Chemical Technology Co., Ltd.), and Lencolo 4051 (Lancolor).

[0048] Further, the method for preparing the self-made color paste is as follows: The self-made color paste is prepared by uniformly mixing blue pigment powder, inorganic filler, grinding resin, acrylate monomer, and wetting and dispersing agent, transferring it to a color paste grinder, grinding it with 0.2 mm zirconia beads until the particle size is ≤ 300 nm, filtering and discharging to obtain the self-made color paste.

[0049] Preferably, the blue pigment is selected from BASF K7090 phthalocyanine blue pigment.

[0050] Preferably, the inorganic filler is selected from at least one of silica powder, talc powder, aluminum hydroxide, and titanium dioxide.

[0051] Preferably, the grinding resin is selected from at least one of L-8430 (Bluecol), BR-1122 (Mitsubishi of Japan), aldehyde-ketone resin A81, and the above-mentioned acrylate polyurethane with polyether polyol as the main chain. More preferably, aldehyde-ketone resin A81 and acrylate polyurethane with polyether polyol as the main chain are selected.

[0052] Preferably, the wetting and dispersing agent is selected from at least one of TEGO Dispers 685 (Degussa of Germany) and BYK-9150 (BYK Chemie of Germany).

[0053] The present invention provides a preparation process for a low-viscosity, atomized, and long-term stable UV insulating inkjet formulation. Mixing a variety of modified acrylate resins, mono-functional, di-functional, tri-functional, tetra-functional, and hexa-functional acrylate monomers, high-efficiency UV additives, and self-made color paste evenly results in a low-viscosity, atomized, and long-term stable UV insulating inkjet. Since this process does not involve any chemical reactions, there are no strict restrictions on the addition order of raw materials, and the mixing steps can be flexibly adjusted according to personal preferences or production habits as long as it is ensured that each component is fully blended.

[0054] Preferably, the process for preparing the atomized, low-viscosity, and long-term stable UV insulating inkjet includes the following steps:

[0055] S1 Mix the acrylate monomer, UV additive, and pre-synthesized modified acrylate resin oligomer evenly to obtain varnish.

[0056] S2 Add the self-made color paste to the varnish obtained in S1 and stir until evenly mixed to obtain a pre-UV insulating inkjet.

[0057] S3 Filter the pre-UV insulating inkjet with a filter paper with a pore size of 0.3 μm, and test whether the inkjet particle size is ≤ 300 nm. Otherwise, re-filter until the particle size meets the requirements. Thus, a low-viscosity, atomized, and long-term stable UV insulating inkjet is obtained.

[0058] The present invention provides a UV insulating coating product, which is obtained by spray-coating the low-viscosity, atomized, and long-term stable UV insulating inkjet proposed in the first aspect onto a 10*10 cm aluminum alloy sheet once, and obtaining a sample product with a coating thickness of 80 - 120 μm through two light-curing processes.

[0059] Preferably, the spraying conditions are that the ink temperature is set at 60°C, the spraying flow rate is 40 mL / min, and the distance between the nozzle and the spraying surface is 10 cm.

[0060] Preferably, the curing intensity is as follows: for the first curing, it is 600 - 800 mj / cm2 and the time is controlled within 1 - 3 s. For the second curing, the intensity is controlled at 1000 - 1500 mj / cm2 and the single curing time is 6 - 10 s.

[0061] The present invention also provides the application of a low-viscosity, atomized, and long-term stable UV insulating inkjet in the insulation protection of the outer packaging of power battery cells.

[0062] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0063] 1. Customized formula innovation: By integrating diverse modified acrylate resins and acrylate monomers with different functionalities, and cooperating with efficient UV additives and self-made color pastes, the present invention realizes the dynamic adjustment of the inkjet formula. This customized solution can accurately control the functional characteristics of the insulating inkjet according to specific application requirements, broadening the usage scenarios.

[0064] 2. High-performance comprehensive characteristics: The provided low-viscosity, atomized, and long-term stable UV insulating inkjet formula not only meets the high-standard insulation requirements of 800V new energy vehicle cells but also demonstrates excellent comprehensive durability, including water boiling resistance, acid and alkali corrosion resistance, electrolyte erosion resistance, salt spray resistance, impact resistance, high adhesion, high shear strength, and rapid curing. This innovation effectively fills the market gap and contributes a safer, more reliable, efficient, durable, and cost-effective solution to the new energy vehicle industry.

[0065] 3. Advanced process optimization: The unique value of the invention also lies in its low viscosity (≤30 cps) and atomization technology (particle size ≤300 nm). The combination of these two not only ensures smooth application in existing inkjet equipment, avoiding the additional cost of hardware upgrades, but also promotes high printing precision and surface smoothness, significantly reducing the risk of nozzle blockage. In addition, by simplifying the production process flow and improving material utilization rate, the present invention successfully improves production efficiency and reduces costs, showing obvious advantages compared with traditional blue film technology. Description of the Drawings

[0066] Figure 1 It is the synthesis route diagram of the low molecular weight hyperbranched acrylate polyurethane of the present invention;

[0067] Figure 2 It is the synthesis route diagram of the acrylate polyurethane with polyether polyol as the main chain of the present invention. Detailed Embodiments

[0068] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0069] Preparation Example 1

[0070] This preparation example provides a method for preparing a low molecular weight hyperbranched acrylate polyurethane:

[0071] Put 66 parts of isophorone diisocyanate, 0.4 part of p-hydroxyanisole and 0.1 part of dibutyltin diacetate into a three-necked flask, stir evenly, and heat up to 60 °C. Slowly dropwise add 12.7 parts of dipentaerythritol that has been completely dissolved in 25 parts of tetrahydrofuran in advance. Heat up to 75 °C and maintain the temperature for reaction for 3 - 5 hours until the residual -NCO in the product reaches the theoretical -NCO to obtain polyurethane intermediate I.

[0072] Heat up polyurethane intermediate I to 75 °C, slowly dropwise add 100 parts of pentaerythritol triacrylate, control the temperature at 90 °C, and continue the reaction until the residual -NCO in the product is less than 5‰, then stop the reaction to obtain the low molecular weight hyperbranched acrylate polyurethane. For the sake of clarity and fluency of the text, "resin 1" will be used as a short name hereinafter.

[0073] In a preferred embodiment, the synthesis route of the low molecular weight hyperbranched acrylate polyurethane is as Figure 1 shown.

[0074] Preparation Example 2

[0075] This preparation example provides a method for preparing an anhydride-modified epoxy acrylate:

[0076] Mix 50 parts of methyltetrahydrophthalic anhydride with 0.1 part of tetrabutylammonium bromide and 0.5 part of 2,6-di-tert-butyl-p-cresol, heat to 70 °C, and slowly dropwise add 80 parts of glycidyl methacrylate. After the addition is complete, heat up to 85 °C for reaction. Measure that the epoxy ester in the product is less than 1 mol / kg and the acid value is less than 2 mg KOH / g to obtain the anhydride-modified epoxy acrylate. "Resin 2" will be used as a short name hereinafter.

[0077] Preparation Example 3

[0078] This preparation example provides a method for preparing an acrylate polyurethane with a polyether polyol as the main chain:

[0079] Heat 60 parts of PPG600 polyol to 110 °C. Under the condition of ensuring the container is sealed, evacuate to a negative pressure of 0.2 MPa and maintain for 1 hour. After the water removal operation is completed, set aside for later use. Heat 39 parts of dicyclohexylmethane diisocyanate to 70 °C, and slowly add dropwise 0.06 part of dioctyltin diacetate and the PPG600 that has undergone water treatment. Heat to 70 °C and maintain the temperature until the residual -NCO in the product reaches the theoretical -NCO to obtain polyurethane intermediate II.

[0080] After adding 0.06 part of dioctyltin diacetate dropwise to polyurethane intermediate II, raise the temperature to 85 °C, add 21.6 parts of hydroxypropyl methacrylate, and continue the reaction until the residual -NCO in the product is less than 5‰, then stop the reaction to obtain an acrylate polyurethane with a polyether polyol as the main chain. Hereinafter, it will be referred to as "resin 3" for short.

[0081] In a preferred embodiment, the synthesis route of the acrylate polyurethane with a polyether polyol as the main chain is as Figure 2 shown.

[0082] Preparation Example 4

[0083] This preparation example provides a method for preparing an acrylate polyurethane oligomer extended with a low-molecular-weight polyol:

[0084] Mix 60 parts of hydroxyethyl methacrylate, 9.5 parts of 1,6-hexanediol, 0.3 part of p-methoxyphenol, and 0.1 part of zinc diacetate evenly, then raise the temperature to 55 °C, slowly add dropwise 39 parts of hexamethylene diisocyanate, raise the temperature to 90 °C, and stop the reaction until the residual -NCO in the product is less than 5‰ to obtain an acrylate polyurethane oligomer extended with a low-molecular-weight polyol. Hereinafter, it will be referred to as "resin 4" for short.

[0085] Preparation Example 5

[0086] This preparation example provides a method for preparing a self-made color paste:

[0087] Mix 30 parts of blue pigment powder, 2 parts of titanium dioxide, 15 parts of aldehyde-ketone resin A81, 20 parts of acrylate polyurethane with a polyether polyol as the main chain (synthesized using PPG600), 80 parts of benzyl acrylate, and 3 parts of BYK9150 evenly, transfer to a color paste grinder, grind with 0.2 mm zirconia beads until the particle size ≤ 300 nm, filter and discharge to obtain a self-made color paste.

[0088] Example 1

[0089] 20 parts of benzyl acrylate, 15 parts of ethoxyethoxyethyl acrylate, 8 parts of ethylene glycol dimethacrylate, 8 parts of trimethylolcyclohexyl acrylate, 6 parts of ethoxylated pentaerythritol tetraacrylate, 5 parts of isobornyl acrylate, 5 parts of tris(2-hydroxyethyl)isocyanurate triacrylate, 3 parts of diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide, 3 parts of ethyl 2,4,6-trimethylbenzoyl phenylphosphinate, 1.8 parts of LTH, 0.1 part of BYK333, 0.1 part of TEGO Airex 900, 3 parts of resin 1 prepared in Preparation Example 1, 5 parts of resin 2 prepared in Preparation Example 2, 8 parts of resin 3 prepared in Preparation Example 3, 9 parts of resin 4 prepared in Preparation Example 4, and 5 parts of the self-made color paste prepared in Preparation Example 5 were added to a reaction kettle and stirred at a high speed until completely and evenly mixed, thus obtaining a low-viscosity, atomized and long-term stable UV insulating inkjet ink.

[0090] Example 2

[0091] 18 parts of isobornyl acrylate, 12 parts of 2-phenoxyethyl acrylate, 8 parts of polyethylene glycol o-phenylphenyl ether acrylate, 8 parts of tetrahydrofuran acrylate, 7 parts of ethoxylated trimethylolpropane triacrylate, 5 parts of 4-acryloylmorpholine, 4 parts of (2-hydroxyethyl)isocyanuric acid triacrylate, 3 parts of 2-isopropylthioxanthone, 3 parts of ethyl 2,4,6-trimethylbenzoyl phenylphosphinate, 1.8 parts of SYG-PM-2, 0.1 part of TEGO Glide100, 0.1 part of BYK-020, 3 parts of resin 1 prepared in Preparation Example 1, 8 parts of resin 2 prepared in Preparation Example 2, 7 parts of resin 3 prepared in Preparation Example 3, 12 parts of resin 4 prepared in Preparation Example 4, and 5 parts of the self-made color paste prepared in Preparation Example 5 were added to a reaction kettle and stirred at a high speed until completely and evenly mixed, thus obtaining a low-viscosity, atomized and long-term stable UV insulating inkjet ink in the reaction kettle.

[0092] Example 3

[0093] 20 parts of dicyclopentenyloxyethyl acrylate, 15 parts of ethoxyethoxyethyl acrylate, 10 parts of dipropylene glycol diacrylate, 8 parts of dipropylene glycol diacrylate, 8 parts of tetrahydrofurfuryl acrylate, 5 parts of propoxylated neopentyl glycol diacrylate, 5 parts of tripropylene glycol diacrylate, 4 parts of diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide, 3 parts of ethyl 2,4,6-trimethylbenzoyl phenylphosphinate, 1.8 parts of Lencolo 4051, 0.1 part of BYK346, 0.1 part of Lencolo 2108, 5 parts of resin 1 prepared in Preparation Example 1, 5 parts of resin 2 prepared in Preparation Example 2, 6 parts of resin 3 prepared in Preparation Example 3, 4 parts of resin 4 prepared in Preparation Example 4, and 5 parts of self-made color paste prepared in Preparation Example 5 were added to a reaction kettle and stirred at high speed until completely and uniformly mixed to obtain a low-viscosity, atomized, and long-term stable UV insulating inkjet.

[0094] Comparative Example 1

[0095] The difference from Example 1 lies in adjusting the resin composition: 25 parts of resin 1 were added alone, and resins 2, 3, and 4 were no longer added. The types and amounts of other components in the formula remained unchanged.

[0096] Comparative Example 2

[0097] The difference from Example 1 lies in adjusting the resin composition: 25 parts of resin 2 were added alone, and resins 1, 3, and 4 were no longer added. The types and amounts of other components in the formula remained unchanged.

[0098] Comparative Example 3

[0099] The difference from Example 1 lies in adjusting the resin composition: 25 parts of resin 3 were added alone, and resins 1, 2, and 4 were no longer added. The types and amounts of other components in the formula remained unchanged.

[0100] Comparative Example 4

[0101] The difference from Example 1 lies in adjusting the resin composition: 25 parts of resin 4 were added alone, and resins 1, 2, and 3 were no longer added. The types and amounts of other components in the formula remained unchanged.

[0102] Comparative Example 5

[0103] The difference from Example 1 lies in not adding adhesion promoters, leveling agents, and defoaming agent components. That is, the addition amounts of LTH, BYK333, and TEGO Airex 900 were 0, and the types and amounts of other components in the formula remained unchanged.

[0104] Comparative Example 6

[0105] The difference from Example 1 is that the components of the color paste are adjusted while the addition amount of the color paste remains unchanged. That is, the self-made color paste in Preparation Example 5 is changed to the following component ratio:

[0106] 30 parts of blue toner, 2 parts of titanium dioxide, 80 parts of lauryl acrylate, 40 parts of tris(2-hydroxyethyl)isocyanurate triacrylate, and 3 parts of BYK9150 are mixed and stirred evenly, transferred to a color paste grinder, and ground with 0.2 mm zirconia beads until the particle size ≤ 300 nm, filtered and discharged to obtain a self-made color paste.

[0107] Experimental Example

[0108] The UV insulating inkjet is spray-coated on a 10*10 cm aluminum alloy sheet at one time, and a sample product with a coating thickness of 100 ± 5 μm is obtained after two photocuring processes.

[0109] The spraying conditions are as follows: the ink temperature is set at 50 °C, the spraying flow rate is 0.15 kg / m2, and the distance between the nozzle and the spraying surface is 10 cm.

[0110] The curing conditions are as follows: the first curing strength is 600 mj / cm2, the curing time is 2 s, the second curing strength is controlled at 1200 mj / cm2, and the curing time is 8 s.

[0111] Test Example

[0112] The above examples and comparative examples are tested as follows, and the test conditions and results are as follows:

[0113] 1. Odor: The inkjet sample is evaluated by the nose-smelling method in a non-interfering environment. If there is no pungent odor or abnormal smell, it meets the standard.

[0114] 2. Viscosity: According to GB / T 1723-1993, the viscosity of the UV inkjet is measured using a rotational viscometer at room temperature (23 ± 2 °C) and relative humidity (50 ± 5%).

[0115] 3. Particle size: According to GB / T 1724-2019, the particle size of the UV inkjet is measured using a laser particle size analyzer. D97 ≤ 300 nm meets the inkjet technology requirements.

[0116] 4. Surface tension: According to GB / T 6541-2012, the UV inkjet is tested using a surface tension meter at room temperature (23 ± 2 °C) and relative humidity (50 ± 5%). The surface tension should be between 22-40 dynes / cm.

[0117] 5. Thermal conductivity: According to ASTM D5470, the thermal conductivity of the UV coating is measured using a steady-state heat flow technique. The thermal conductivity should be ≥ 0.23 W / mk.

[0118] 6. Flame retardancy: According to the UL94 standard, a vertical burning test device is used to test the flame retardancy of the coating. The flame retardancy should reach the V0 grade.

[0119] 7. Appearance of the sample piece: The surface coating of the sample piece is inspected by visual method and should be uniform and free of defects.

[0120] 8. Coating thickness: According to GB / T 13452.2-2008, a film thickness gauge is used to test the coating thickness. The thickness should be within the tolerance range of 110±20.

[0121] 9. Pencil hardness: According to GB / T 6739-2006, a pencil hardness tester is used to test the hardness of the coating. The hardness should be ≥1H.

[0122] 10. Adhesion: According to GB / T 9286, the cross-cut method is used to test the adhesion of the coating on the aluminum surface. The adhesion should reach grade 0.

[0123] 11. Bending deformation: According to GB / T 6742-86, a shaft rod with a curvature radius of 20mm is used to test the bending deformation of the sample piece. The coating is considered qualified if there are no defects such as paint peeling and cracks.

[0124] 12. Shear strength: According to GB / T 7124, a tensile testing machine is used to test the shear strength of the coating. The shear strength should be ≥10MPa.

[0125] 13. Tensile strength: According to GB / T 6329-1996, a tensile testing machine is used to test the tensile strength of the coating. The tensile strength should be ≥10MPa.

[0126] 14. Impact resistance: According to GB / T 1732-2020, the falling weight impact method is used to test the impact resistance of the coating. After a 1kg falling weight drops from a height of 50cm, the coating should have no defects such as paint peeling and cracks and meet the insulation voltage withstand requirements.

[0127] 15. Abrasion resistance: According to GB-T 1689-2014, an abrasion tester is used to test the abrasion resistance of the coating. After 1000 reciprocating cycles with a load of 1kg, the coating should not be worn through and meet the insulation voltage withstand requirements.

[0128] 16. Insulation resistance: According to GB-T 10064-2006, an insulation resistance measuring instrument is used to test the insulation resistance of the coating. Under a DC 1kV voltage for 5s, the insulation resistance should be ≥1GΩ.

[0129] 17. Breakdown voltage: According to GB-T 1408.1-2016, a coil element withstand voltage tester is used to test the breakdown voltage of the coating. The coating should not be broken down under DC 4kV and AC 2.23kV and meet the insulation voltage withstand requirements.

[0130] 18. Electrolyte resistance: The electrolyte is sealed and soaked at room temperature for 10 days. After testing, there are no blisters, cracks, etc. on the coating, and the bonding strength requirement with the structural adhesive is met. The cross-cut test passes grade 0, meeting the insulation and voltage-withstanding requirements.

[0131] 19. Acid resistance: According to GB / T 9274-1988, the coating is soaked in 5% HCl for 2 hours. After testing, there are no blisters, cracks, etc. on the coating, and the bonding strength requirement with the structural adhesive is met. The cross-cut test passes grade 0, meeting the insulation and voltage-withstanding requirements.

[0132] 20. Alkaline resistance: According to GB / T 9274-1988, the coating is soaked in 5% NaOH for 2 hours. After testing, there are no blisters, cracks, etc. on the coating, and the bonding strength requirement with the structural adhesive is met. The cross-cut test passes grade 0, meeting the insulation and voltage-withstanding requirements.

[0133] 21. Water resistance: According to GB / T 1733-1993, the coating is soaked in deionized water at room temperature for 168 hours. After testing, there are no blisters, cracks, etc. on the coating, and the bonding strength requirement with the structural adhesive is met. The cross-cut test passes grade 0, meeting the insulation and voltage-withstanding requirements.

[0134] 22. Salt spray resistance: According to ASTM B117, a salt spray test machine is used to test the salt spray resistance of the coating. After testing, there are no blisters, cracks, etc. on the coating, and the bonding strength requirement with the structural adhesive is met. The cross-cut test passes grade 0, meeting the insulation and voltage-withstanding requirements.

[0135] 23. High temperature and high humidity resistance: The experimental temperature is set at 85°C and the humidity at 85%. The coating sample pieces are stored for 7 days. After testing, there are no blisters, cracks, etc. on the coating, and the bonding strength requirement with the structural adhesive is met. The cross-cut test passes grade 0, meeting the insulation and voltage-withstanding requirements.

[0136] Thermal shock resistance: Set the temperature cycle test at -25°C and 40°C, and the continuous 4 cycles are completed. After testing, there are no blisters, cracks, etc. on the coating, and the bonding strength requirement with the structural adhesive is met. The cross-cut test passes grade 0, meeting the insulation and voltage-withstanding requirements.

[0137] Table 1: Summary Table of Inkjet and Coating Performance Tests

[0138]

[0139]

[0140] Table 2: Storage Stability Test Data of Examples at 60°C

[0141]

[0142] According to the data in Table 1, Examples 1-3 provided by this patent meet the requirements of high-precision printing in terms of viscosity (≤30 cps) and particle size (D97≤300 nm). In addition, Table 2 shows that at a printing temperature of 60 °C, Examples 1-3 can be stably stored for more than 60 days, significantly reducing the risk of nozzle blockage, thereby avoiding economic losses during the production process. At the same time, Examples 1-3 meet the strict requirements of the 800V new energy vehicle battery cells for the electrical properties, weather resistance, and stability of the insulation coating. Therefore, the spraying solution proposed in this patent can effectively replace the existing blue film technology and provide reliable insulation technical support for the further improvement of battery voltage.

[0143] According to the comparison results between Example 1 and Comparative Example 1, adding low molecular weight hyperbranched acrylate polyurethane can effectively improve the mechanical properties and chemical resistance of the coating. This effect is mainly attributed to the dense acrylate functional groups and the dense network structure formed during the curing process, but at the same time, it will sacrifice certain adhesion and bending properties.

[0144] It can be seen from the comparison between Example 1 and Comparative Example 2 that adding anhydride-modified epoxy acrylate can significantly enhance the electrolyte resistance of the material, which may be due to the reaction of epoxy groups with anhydrides to form a stable three-dimensional network structure.

[0145] The comparison between Example 1 and Comparative Example 3 shows that using acrylate polyurethane with polyether polyol as the main chain can improve the adhesion, bending deformation ability, and shear strength of the material. This may be because its surface contains a large number of polar groups, thus better binding to the aluminum surface. However, excessive addition of this resin will lead to an increase in viscosity and a decrease in chemical resistance.

[0146] The comparison results between Example 1 and Comparative Example 4 show that adding acrylate polyurethane oligomer chain-extended with small molecular weight diol can reduce the viscosity of the system while maintaining good adhesion and hardness.

[0147] The comparison between Example 1 and Comparative Example 5 shows that the addition of an adhesion promoter helps to improve the adhesion of the coating. It should be noted that due to the absence of an antifoaming agent in Comparative Example 5, pores appeared on the coating surface, so only its mechanical properties were tested. The presence of these pores may lead to high-voltage breakdown, so its electrical properties were not tested.

[0148] The comparison between Example 1 and Comparative Example 6 shows that the color paste without adding the self-made resin will cause the aggregation of color powder particles, with a particle size reaching 498 nm, which is larger than the nozzle diameter and cannot be used for spraying sample preparation.

[0149] In summary, the present invention provides a method for preparing and applying a micronized stable UV insulating inkjet for a new energy vehicle battery cell, which provides a low-viscosity, micronized and long-term stable UV insulating inkjet that can stably exist for a long time at a cartridge temperature of 60°C, avoiding the risk of nozzle clogging caused by increased viscosity or increased particle size. The formulation contains a variety of low molecular weight hyperbranched modified acrylic resins, mono-functional, di-functional, tri-functional, tetra-functional and hexa-functional acrylate monomers, high-efficiency UV additives and self-made color pastes. By precisely preparing the above raw materials and supplemented by scientific formulation design and process control, a UV inkjet with simultaneous water boiling resistance, acid and alkali resistance, electrolyte resistance, impact resistance, salt spray resistance, high adhesion, high shear strength, high insulation and rapid curing is finally prepared.

[0150] It should be noted that, in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variation thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device.

[0151] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A preparation method of a micronized stable UV insulating inkjet, characterized in that, The method comprises the following steps: S1. Mix acrylate monomers, UV additives, and modified acrylate resin evenly to obtain varnish; S2. Add the self-made color paste to the varnish obtained in S1 and stir until evenly mixed to obtain a pre-UV insulating inkjet; S3. Filter the pre-UV insulating inkjet with a filter paper having a pore size of 0.3 μm, and test whether the inkjet particle size is ≤ 300 nm. Otherwise, re-filter until the particle size meets the requirements, that is, a low-viscosity, atomized, and long-term stable UV insulating inkjet is obtained; The components thereof are composed of the following parts by weight: 20 - 40 parts of low molecular weight hyperbranched modified acrylic resin, 50 - 70 parts of acrylate monomers, 2 - 10 parts of UV additives, and 1 - 7 parts of self-made color paste.

2. The preparation method of a micronized stable UV insulating inkjet according to claim 1, characterized in that: The low molecular weight hyperbranched modified acrylic resin includes low molecular weight hyperbranched acrylate polyurethane, acid anhydride-modified epoxy acrylate, acrylate polyurethane with polyether polyol as the main chain, and acrylate polyurethane oligomer chain-extended with low molecular weight polyol.

3. The preparation method of a micronized stable UV insulating inkjet according to claim 2, characterized in that: The low molecular weight hyperbranched acrylate polyurethane is prepared by the following method: Diisocyanate undergoes hydroxyl addition capping with a core molecule and a hydroxyl-containing acrylate monomer respectively under the action of catalyst I.

4. The preparation method of a micronized stable UV insulating inkjet according to claim 3, characterized in that: The core molecule is selected from at least one of pentaerythritol and dipentaerythritol.

5. The preparation method of a micronized stable UV insulating inkjet according to claim 1, characterized in that: The acrylate monomer is obtained by the addition polymerization reaction of glycidyl methacrylate with an acid anhydride under the action of catalyst II.

6. The preparation method of a micronized stable UV insulating inkjet according to claim 5, characterized in that: The acid anhydride is selected from at least one of phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, and tetrahydrophthalic anhydride.

7. The preparation method of a micronized stable UV insulating inkjet according to claim 2, characterized in that: The acrylate polyurethane with polyether polyol as the main chain is obtained by the hydroxyl addition capping of diisocyanate with polyether polyol and a hydroxyl-containing acrylate monomer respectively under the action of catalyst I.

8. The preparation method of a micronized stable UV-insulating inkjet according to claim 7, characterized in that: The acrylate polyurethane oligomer chain-extended with low molecular weight polyol is obtained by the hydroxyl addition capping of diisocyanate with low molecular weight polyol and a hydroxyl-containing acrylate monomer respectively under the action of catalyst I.

9. The preparation method of a micronized stable UV insulating inkjet according to claim 1, wherein: The preparation method of the self-made color paste is as follows: Mix color powder, inorganic filler, grinding resin, acrylate monomer, and wetting dispersant evenly, transfer to a color paste grinder, grind with 0.2 mm zirconia beads until the particle size is ≤ 300 nm, filter and discharge to obtain the self-made color paste.

10. Application of a micronized stable UV insulating inkjet, characterized in that: Apply the UV insulating inkjet to the insulating protection of the outer packaging of the power battery cell of a new energy vehicle.

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