Insulating coating ink, insulating coating, preparation method of insulating coating and battery

Abstract

The invention provides insulating coating ink, an insulating coating, a preparation method of the insulating coating and a battery, and belongs to the technical field of insulating coatings, and the insulating coating ink comprises a prepolymer, a monomer, toner and a photoinitiator. In the toner, the mass ratio of phthalocyanine blue is 60%-90%, the mass ratio of phthalocyanine green is 0%-30%, and the mass ratio of titanium dioxide is 10%-40%. In the photoinitiators, the mass ratio of the cracking type free radical photoinitiator is 50%-90%, and the mass ratio of the hydrogen abstracting type free radical photoinitiator is 10%-50%; in the cracking type free radical photoinitiator, the mass ratio of the short-medium wave absorption initiator is 40-70%, and the mass ratio of the long-wave absorption initiator is 30-60%. In the insulating coating ink, the mass ratio of the photoinitiator is 1%-5%, and the mass ratio of the toner is 0.2%-1.5%. The insulating coating ink provided by the invention can improve the heat resistance, weather resistance, wear resistance and aging and yellowing resistance of an insulating coating.

Description

Technical Field

[0001] This application relates to the field of insulating coating technology, specifically to an insulating coating ink, an insulating coating and its preparation method, and a battery. Background Technology

[0002] Currently, lithium-ion batteries commonly use conductive metal casings such as aluminum and stainless steel. During battery assembly or integration with peripheral devices, if the metal casing is directly exposed and in contact with external conductors, it can easily induce short circuits, leading to abnormal battery performance and potential safety hazards such as thermal runaway. The risk of short circuits is typically mitigated by covering the metal casing surface with a polymer insulating protective film. UV insulating coatings are a significant innovation in the power battery field in recent years. Their core principle is to achieve efficient and environmentally friendly insulation through ultraviolet (UV) curing technology, gradually replacing traditional insulating protective films.

[0003] Currently, the commonly used colorant in UV insulating coating inks is a mixture of phthalocyanine blue, phthalocyanine green, and titanium dioxide. This mixture gives the insulating coating a low or opaque state, reducing the oxidative degradation of polymer molecules by ultraviolet light, minimizing thermal deformation caused by the absorption of infrared light by the polymer, and improving the heat resistance, weather resistance, and abrasion resistance of the insulating coating. However, due to the low light transmittance of the ink, incomplete curing is prone to occur during the UV curing process, resulting in a low degree of cross-linking and making the insulating coating susceptible to aging and yellowing. Summary of the Invention

[0004] The embodiments of this application provide an insulating coating ink, an insulating coating and its preparation method, and a battery, which can improve the heat resistance, weather resistance and wear resistance of the insulating coating, while improving the aging and yellowing resistance of the insulating coating.

[0005] In a first aspect, embodiments of this application provide an insulating coating ink, comprising:

[0006] Prepolymer;

[0007] monomer;

[0008] Pigment powder, comprising at least two of phthalocyanine blue, phthalocyanine green and titanium dioxide, wherein the mass percentage of phthalocyanine blue is 60%-90%, the mass percentage of phthalocyanine green is 0%-30%, and the mass percentage of titanium dioxide is 10%-40%.

[0009] Photoinitiators include cleavage-type free radical photoinitiators and hydrogen-abstraction-type free radical photoinitiators; the mass percentage of cleavage-type free radical photoinitiators is 50%-90%, and the mass percentage of hydrogen-abstraction-type free radical photoinitiators is 10%-50%; cleavage-type free radical photoinitiators include short- and medium-wavelength absorption initiators and long-wavelength absorption initiators; the mass percentage of short- and medium-wavelength absorption initiators is 40%-70%, and the mass percentage of long-wavelength absorption initiators is 30%-60%;

[0010] In the insulating coating ink, the mass percentage of photoinitiator is 1%-5%, and the mass percentage of pigment is 0.2%-1.5%.

[0011] In the insulating coating ink provided in this application embodiment, the prepolymer and monomer can form a cross-linked network, thereby ensuring the mechanical strength of the resulting insulating coating. By including at least two of the pigments—phthalocyanine blue, phthalocyanine green, and titanium dioxide—and ensuring the mass percentage meets the above requirements, the resulting insulating coating can exhibit low light transmittance, thereby improving the heat resistance, weather resistance, and abrasion resistance of the insulating coating. The pyrolysis-type free radical photoinitiator includes short- and medium-wavelength absorption initiators and long-wavelength photoinitiators, enabling full-band response during curing. The hydrogen-abstracting free radical photoinitiator has a large absorption wavelength and a high extinction coefficient, allowing it to compete for light absorption in the presence of pigments. It can act as a sensitizer, not only initiating polymerization itself but also exchanging energy with the pyrolysis-type free radical photoinitiator in the excited triplet state, causing the pyrolysis-type free radical photoinitiator to directly transition from the ground state to the excited triplet state, indirectly achieving photoactivation of the pyrolysis-type free radical photoinitiator. By leveraging the synergistic effect of pyrolysis-type and hydrogen-abstracting free radical photoinitiators, photoinitiator efficiency can be improved, enabling simultaneous surface and deep curing of the insulating coating. Furthermore, by controlling the mass percentage of pigment in the insulating coating ink, a good sensitizing effect on the photoinitiator can be achieved while maintaining the low light transmittance of the insulating coating, thereby improving the utilization rate of ultraviolet light and the curing rate during the curing process. Controlling the mass percentage of photoinitiator in the insulating coating ink can also ensure the crosslinking rate during the curing process. In other words, the insulating coating ink provided in this application can ensure low light transmittance, resulting in an insulating coating with good heat resistance, weather resistance, and abrasion resistance, while also ensuring the degree of crosslinking during curing, improving the curing effect, and enhancing the aging and yellowing resistance of the resulting insulating coating.

[0012] In some embodiments, the absorption wavelength range of the short-to-medium wave absorption initiator is 200 nm to 340 nm;

[0013] And / or, the absorption wavelength range of the long-wavelength absorption initiator is 310nm-450nm.

[0014] By utilizing short- and medium-wavelength absorbing initiators and long-wavelength absorbing initiators within the aforementioned wavelength ranges, a full-band response can be achieved during photocuring, enabling simultaneous curing of both surface and deep layers and ensuring optimal photocuring results. Specifically, short- and medium-wavelength absorbing initiators, with an absorption wavelength range of 200nm-340nm, can rapidly decompose to generate free radicals, increasing the crosslinking rate. Their relatively weak penetration helps achieve uniform surface curing. Long-wavelength absorbing initiators, with an absorption wavelength range of 310nm-450nm, possess stronger penetration capabilities, enabling deep curing and are suitable for low-transmittance systems. Furthermore, long-wavelength absorbing initiators exhibit excellent antioxidant and polymerization-inhibiting effects, improving the curing rate while ensuring optimal curing results.

[0015] In some embodiments, the short- and medium-wave absorption initiator includes at least one of 1-hydroxycyclohexylphenyl ketone, benzoin dimethyl ether (benzoyl dimethyl ketal), and 2-hydroxy-2-methyl-1-phenyl-1-propanone;

[0016] And / or, the long-wave absorption initiator includes at least one of 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphine, (2,4,6-trimethyl-3-benzoyl)benzoyl diphenylphosphine oxide, and 4-diethylaminobenzoyl diphenylphosphine oxide.

[0017] The aforementioned short- and medium-wave absorption initiators exhibit efficient and rapid curing capabilities, along with low cost and small dosage. The aforementioned long-wave absorption initiators demonstrate outstanding deep curing ability, excellent antioxidant polymerization inhibition effect, low migration rate, and superior environmental friendliness.

[0018] In some embodiments, hydrogen-abstracting free radical photoinitiators include a main initiator and a co-initiator;

[0019] In hydrogen-abstracting free radical photoinitiators, the mass percentage of the co-initiator is 0.5%-3%.

[0020] Hydrogen-abstracting free radical photoinitiators achieve efficient and controllable photocuring processes through the synergistic effect of the main initiator and the co-initiator. By maintaining the mass percentage of the co-initiator in the hydrogen-abstracting free radical photoinitiator at 0.5%-3%, crosslinking efficiency can be balanced, curing effect can be guaranteed, and material cost can be reduced.

[0021] In some embodiments, in the insulating coating ink, the mass percentage of the short- and medium-wave absorption initiator is P1, the mass percentage of the long-wave absorption initiator is P2, the mass percentage of the co-initiator is P3, the mass percentage of phthalocyanine blue is P4, the mass percentage of phthalocyanine green is P5, and the mass percentage of titanium dioxide is P6, satisfying the following:

[0022] P1+P2+P3=a×P4+b×P5-c×P6;

[0023] Where 4≤a≤6, 4≤b≤6, and 1≤c≤1.25.

[0024] Phthalocyanine blue and phthalocyanine green are strong light-absorbing pigments, which weaken the absorption efficiency of photoinitiators in specific wavelength bands. Titanium dioxide can enhance light penetration depth through reflection and scattering, but excessive titanium dioxide will reduce the system's transmittance. By ensuring that P1, P2, P3 and P4, P5, P6 satisfy the above formula, the mass percentage of the photoinitiator can be correlated with the type and content of pigments in the color powder. This compensates for the loss of absorption efficiency caused by phthalocyanine blue and phthalocyanine green, considers the light-transmitting enhancement effect of titanium dioxide, and avoids increased costs and reduced curing effect due to excessive addition of photoinitiator. In other words, this embodiment achieves a balance between photocuring effect and pigment hiding power by synergistically combining the amount of photoinitiator added with the type and amount of pigments in the color powder, resulting in an insulating coating with good heat resistance, weather resistance, abrasion resistance, and resistance to aging and yellowing.

[0025] In some embodiments, the main initiator includes at least one of thioxanthones, 2-chlorothioxanthones, 1-chloro-4-propoxythioxanthones, isopropylthioxanthones, and 2,4-diethylthioxanthones;

[0026] Co-initiators include at least one of triethylamine, triethanolamine, methyldiethanolamine, N-methyldiethanolamine, ethyl-4-dimethylaminobenzoate, pentaerythritol, glycerol, polyethylene glycol, 1-octylthiol, trimethylolpropane tris(3-mercaptopropionate), and methyl 4-mercaptobenzoate.

[0027] Thioxanthone-based primary initiators exhibit strong absorption characteristics in the 350nm-450nm wavelength range, which can improve light energy utilization. Furthermore, their long triplet lifetime provides ample time for the hydrogen transfer reaction, thus enhancing initiation efficiency. The aforementioned co-initiators possess excellent hydrogen transfer performance and low-oxygen inhibition properties, ensuring efficient hydrogen supply and thus, high initiation efficiency.

[0028] In some embodiments, the prepolymer in the insulating coating ink is 20%-50% by mass;

[0029] And / or, in insulating coating inks, the monomer mass percentage is 30%-80%.

[0030] The prepolymer's molecular structure contains numerous polar groups, enabling it to form a dense cross-linked network and ensuring the mechanical strength of the resulting insulating coating. The monomer has a dilution and cross-linking balancing effect, reducing the viscosity of the insulating coating ink and participating in the cross-linking reaction. By maintaining the mass percentages of prepolymer and monomer within the aforementioned range, the cross-linking density and flexibility of the resulting insulating coating can be balanced.

[0031] In some embodiments, the insulating coating ink further includes additives, wherein the additives include color powder;

[0032] In insulating coating inks, the mass percentage of additives is 0.2%-10%.

[0033] Additives, including colorants, help ensure the hiding power of the resulting insulating coating. Leveling agents, polymerization inhibitors, and other additives reduce surface defects, lower oxygen inhibition, and ensure proper curing. By keeping the mass percentage of additives within the aforementioned range, the quality of the resulting insulating coating can be improved.

[0034] In some embodiments, the prepolymer includes bisphenol-type epoxy acrylate and polyester-based polyurethane acrylate;

[0035] The mass ratio of bisphenol-type epoxy acrylate to polyester-type polyurethane acrylate is 1:(2-6).

[0036] Bisphenolic epoxy acrylates have a faster curing rate and excellent hardness and mechanical properties, while polyester-based polyurethane acrylates offer better flexibility and weather resistance, as well as good abrasion resistance and solvent resistance. By maintaining the mass ratio of bisphenolic epoxy acrylate to polyester-based polyurethane acrylate within the aforementioned range, insulation properties, mechanical strength, and flexibility can be balanced.

[0037] In some embodiments, the molecular weight of the prepolymer is 1000 Da-2000 Da.

[0038] By setting the molecular weight of the prepolymer to 1000 Da-2000 Da, the viscosity of the insulating coating ink can be reduced, ensuring good curing efficiency and reducing the volume shrinkage rate after curing. Furthermore, the higher crosslinking density can improve the mechanical and chemical properties of the resulting insulating coating.

[0039] In some embodiments, the monomer includes at least two of the following: monofunctional acrylate monomers, difunctional acrylate monomers, and trifunctional acrylate monomers.

[0040] Among the monomers, the mass percentage of monofunctional acrylate monomers is 55%-85%, the mass percentage of difunctional acrylate monomers is 5%-25%, and the mass percentage of trifunctional acrylate monomers is 0%-20%.

[0041] Monofunctional acrylate monomers can control the curing speed and reduce stress, while difunctional and trifunctional acrylate monomers can improve crosslinking density and hardness. By keeping the mass percentages of monofunctional, difunctional, and trifunctional acrylate monomers within the above-mentioned ranges, it is possible to balance curing speed, mechanical properties, flexibility, shrinkage, and cost.

[0042] In some embodiments, the monofunctional acrylate monomer includes at least one of ethoxyethoxyacrylate, isoborneol acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and butyl acrylate.

[0043] And / or, the bifunctional acrylate monomers include at least one of dipropylene glycol diacrylate, ditripropylene glycol diacrylate, 1,6-hexanediol diacrylate and neopentyl glycol diacrylate;

[0044] And / or, the trifunctional acrylate monomers include at least one of trimethylolpropane diacrylate, ethoxylated trimethylolpropane diacrylate, and pentaerythritol triacrylate.

[0045] The aforementioned monofunctional acrylate monomers exhibit good flexibility and weather resistance, and can improve adhesion. The aforementioned difunctional acrylate monomers have a faster curing speed and lower shrinkage. The aforementioned trifunctional acrylate monomers provide good hardness and impact resistance, and have low shrinkage properties.

[0046] In some embodiments, the additives include leveling agents, polymerization inhibitors, and color pastes; wherein the color pastes include color powder and color paste solvents;

[0047] In insulating coating inks, the mass percentage of leveling agent is 0.2%-1.5%;

[0048] And / or, in the insulating coating ink, the polymerization inhibitor contains 0.01%-0.5% by mass;

[0049] And / or, in insulating coating inks, the mass percentage of color paste is 0.2%-10%.

[0050] Leveling agents reduce the surface tension of insulating coating inks, helping to eliminate surface defects during the leveling process and ensuring the uniformity of the insulating coating. Polymer inhibitors suppress free radical polymerization, improving the stability of insulating coating inks during storage and regulating the curing speed. Color pastes provide color and meet hiding power requirements; by including the aforementioned color powders and solvents in the color paste, the color paste can be evenly dispersed in the insulating coating ink, ensuring stability.

[0051] In some embodiments, the leveling agent includes a polyether-modified silicone leveling agent;

[0052] And / or, polymerization inhibitors include hydroquinone.

[0053] Polyether-modified silicone leveling agents exhibit excellent leveling properties and good wetting properties, along with good thermal stability, meeting application requirements. Hydroquinone has a lower cost and higher polymerization inhibition efficiency.

[0054] In some embodiments, the particle size D50 of the insulating coating ink is ≤0.4μm.

[0055] By ensuring that the particle size D50 of the insulating coating is within the above-mentioned range, the density of the resulting insulating coating can be improved, the surface smoothness can be enhanced, good resistance to thermal aging and chemical corrosion can be guaranteed, and the long-term stability and reliability of the insulating coating can be improved.

[0056] Among them, the particle size D50 of the insulating coating ink refers to the particle size D50 of the particles in the insulating coating ink.

[0057] Secondly, embodiments of this application provide a method for preparing an insulating coating, comprising:

[0058] The insulating coating ink described above is applied to the substrate surface to form a coating to be cured;

[0059] The coating to be cured is then cured to obtain an insulating coating.

[0060] The method for preparing the insulating coating provided in this application has all the beneficial effects of the insulating coating ink described above, and will not be repeated here.

[0061] In some embodiments, curing the coating to be cured includes:

[0062] Use an LED or electrodeless lamp to cure the coating for 1-8 seconds;

[0063] The LED light includes a first LED with a wavelength of 365nm and a second LED with a wavelength of 395nm.

[0064] By using LEDs or electrodeless lamps with two wavelengths, the wavelength response range of the insulating coating ink can be matched, ensuring the curing rate and curing effect, and improving the performance of the insulating coating.

[0065] Thirdly, embodiments of this application provide an insulating coating, including the insulating coating ink as described above, and / or prepared using the insulating coating preparation method described above.

[0066] The insulating coating provided in this application embodiment has all the beneficial effects of the insulating coating ink described above, which will not be repeated here.

[0067] In some embodiments, the thickness of the insulating coating is 60 μm-140 μm.

[0068] By keeping the thickness of the insulating coating within the above range, good insulation performance, mechanical strength and durability can be guaranteed, while achieving lightweighting and cost reduction.

[0069] Thirdly, embodiments of this application provide a battery, including a housing, wherein at least one surface of the housing is provided with an insulating coating as described above.

[0070] The battery provided in this application embodiment has all the beneficial effects of the insulating coating ink as described above, which will not be repeated here. Detailed Implementation

[0071] The technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Furthermore, it should be understood that the specific implementation methods described herein are only for illustration and explanation of this application and are not intended to limit this application.

[0072] In a first aspect, embodiments of this application provide a battery, including a casing, wherein at least one surface of the casing is provided with an insulating coating as described above. By providing an insulating coating on the battery casing, the insulation performance of the casing can be guaranteed, short circuits caused by direct contact between the casing and external circuits can be avoided, and the insulating coating has better aesthetics, higher peel strength, and higher thermal stability compared to traditional PET blue film.

[0073] Secondly, embodiments of this application provide an insulating coating ink, comprising a prepolymer, monomers, pigments, and a photoinitiator. The pigments include at least two of phthalocyanine blue, phthalocyanine green, and titanium dioxide, wherein the mass percentage of phthalocyanine blue is 60%-90%, the mass percentage of phthalocyanine green is 0%-30%, and the mass percentage of titanium dioxide is 10%-40%. The photoinitiator includes a pyrolysis-type free radical photoinitiator and a hydrogen-abstraction-type free radical photoinitiator; wherein the mass percentage of the pyrolysis-type free radical photoinitiator is 50%-90%, and the mass percentage of the hydrogen-abstraction-type free radical photoinitiator is 10%-50%; the pyrolysis-type free radical photoinitiator includes short- and medium-wave absorption initiators and long-wave absorption initiators, wherein the mass percentage of the short- and medium-wave absorption initiators is 40%-70%, and the mass percentage of the long-wave absorption initiator is 30%-60%. In the insulating coating ink, the mass percentage of the photoinitiator is 1%-5%, and the mass percentage of the pigment is 0.2%-1.5%.

[0074] In the insulating coating ink provided in this application embodiment, the prepolymer and monomer can form a cross-linked network, thereby ensuring the mechanical strength of the resulting insulating coating. By including at least two of the pigments—phthalocyanine blue, phthalocyanine green, and titanium dioxide—and ensuring the mass percentage meets the above requirements, the resulting insulating coating can exhibit low light transmittance, thereby improving the heat resistance, weather resistance, and abrasion resistance of the insulating coating. The pyrolysis-type free radical photoinitiator includes short- and medium-wavelength absorption initiators and long-wavelength photoinitiators, enabling full-band response during curing. The hydrogen-abstracting free radical photoinitiator has a large absorption wavelength and a high extinction coefficient, allowing it to compete for light absorption in the presence of pigments. It can act as a sensitizer, not only initiating polymerization itself but also exchanging energy with the pyrolysis-type free radical photoinitiator in the excited triplet state, causing the pyrolysis-type free radical photoinitiator to directly transition from the ground state to the excited triplet state, indirectly achieving photoactivation of the pyrolysis-type free radical photoinitiator. By leveraging the synergistic effect of pyrolysis-type and hydrogen-abstracting free radical photoinitiators, photoinitiator efficiency can be improved, enabling simultaneous surface and deep curing of the insulating coating. Furthermore, by controlling the mass percentage of pigment in the insulating coating ink, a good sensitizing effect on the photoinitiator can be achieved while maintaining the low light transmittance of the insulating coating, thereby improving the utilization rate of ultraviolet light and the curing rate during the curing process. Controlling the mass percentage of photoinitiator in the insulating coating ink can also ensure the crosslinking rate during the curing process. In other words, the insulating coating ink provided in this application can ensure low light transmittance, resulting in an insulating coating with good heat resistance, weather resistance, and abrasion resistance, while also ensuring the degree of crosslinking during curing, improving the curing effect, and enhancing the aging and yellowing resistance of the resulting insulating coating.

[0075] Pigments are an important coloring component in insulating coating inks. Pigments possess sufficient transmittance within a certain spectral range, allowing photoinitiators to absorb light without being affected by pigment competition; this range is called the pigment's "spectral window." The absorption of ultraviolet light by pigments affects the initiation efficiency of photoinitiators. In the insulating coating inks provided in this application, by adjusting the type of pigment and its mass percentage in the insulating coating ink, as well as the type of photoinitiator and its mass percentage in the insulating coating ink, it is possible to ensure that the resulting insulating coating has good hiding power while maintaining high initiation efficiency, high curing rate, and high crosslinking degree. This results in an insulating coating with good heat resistance, weather resistance, abrasion resistance, and resistance to aging and yellowing.

[0076] For example, in the pigment, the mass percentage of phthalocyanine blue can be 60%, 65%, 70%, 75%, 80%, 85%, or 90%, the mass percentage of phthalocyanine green can be 0%, 5%, 10%, 15%, 20%, 25%, or 30%, and the mass percentage of titanium dioxide can be 10%, 15%, 20%, 25%, 30%, 35%, or 40%. In the photoinitiator, the mass percentage of the cleavage-type free radical photoinitiator can be 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90%, and the mass percentage of the hydrogen abstraction-type free radical photoinitiator can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%. In the cleavage-type free radical photoinitiator, the mass percentage of the short- and medium-wavelength absorbing initiator can be 40%, 45%, 50%, 55%, 60%, 65%, or 70%, and the mass percentage of the long-wavelength absorbing initiator can be 30%, 35%, 40%, 45%, 50%, 55%, or 60%. In insulating coating inks, the mass percentage of photoinitiator can be 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%, and the mass percentage of pigment can be 0.2%, 0.5%, 0.7%, 1%, 1.2%, or 1.5%.

[0077] In some embodiments, the absorption wavelength range of the short-to-medium wave absorption initiator is 200 nm to 340 nm.

[0078] The absorption wavelength range of the short- and medium-wave absorption initiator is 200nm-340nm. It can rapidly decompose to generate free radicals, thereby increasing the crosslinking rate. Its penetration is relatively weak, which helps to achieve uniform curing of the surface layer.

[0079] In some embodiments, the absorption wavelength range of the long-wavelength absorption initiator is 310 nm to 450 nm.

[0080] Long-wave absorption initiators have an absorption wavelength range of 310nm-450nm, stronger penetration ability, can cure deep layers, and are suitable for low light transmittance systems. In addition, long-wave absorption initiators have good antioxidant polymerization inhibition effect, which improves the curing rate while ensuring the curing effect.

[0081] By using short- and medium-wave absorption initiators and long-wave absorption initiators with wavelengths within the aforementioned range, a full-band response can be achieved during the photocuring process, enabling simultaneous curing of the surface and deep layers and ensuring the photocuring effect.

[0082] In some embodiments, the short- and medium-wave absorption initiator includes at least one of 1-hydroxycyclohexylphenyl ketone (Irgacure 184), benzoin dimethyl ether (benzoyl dimethyl ketal) (Irgacure 651), and 2-hydroxy-2-methyl-1-phenyl-1-propanone (Irgacure 1173);

[0083] And / or, the long-wave absorption initiator includes at least one of 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone (Irgacure 907), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone (Irgacure 369), phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide (Irgacure 819), diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), ethyl 2,4,6-trimethylbenzoylphenylphosphonate (TPO-L), (2,4,6-trimethyl-3-benzoyl)benzoyl diphenylphosphine oxide (BzTPO), and 4-diethylaminobenzoyl diphenylphosphine oxide (DEAPO).

[0084] The aforementioned short- and medium-wave absorption initiators exhibit efficient and rapid curing capabilities, along with low cost and small dosage. The aforementioned long-wave absorption initiators demonstrate outstanding deep curing ability, excellent antioxidant polymerization inhibition effect, low migration rate, and superior environmental friendliness.

[0085] In some embodiments, hydrogen-abstracting radical photoinitiators include a primary initiator and a co-initiator. In hydrogen-abstracting radical photoinitiators, the mass percentage of the co-initiator is 0.5%-3%.

[0086] Hydrogen-abstracting free radical photoinitiators achieve efficient and controllable photocuring processes through the synergistic effect of the main initiator and the co-initiator. By maintaining the mass percentage of the co-initiator in the hydrogen-abstracting free radical photoinitiator at 0.5%-3%, crosslinking efficiency can be balanced, curing effect can be guaranteed, and material cost can be reduced.

[0087] This is a hydrogen-abstraction type free radical photoinitiator system using thioxanthone as the main initiator and triethylamine as the co-initiator. Upon exposure to light of a specific wavelength, the main initiator transitions to an excited state and interacts with the ground-state co-initiator, causing electrons to transfer from the co-initiator to the main initiator, forming an ion-pair intermediate of the excited-state complex. Protons transfer from the α-position of the co-initiator to the main initiator, forming ketone radicals derived from the main initiator and free radicals derived from the co-initiator. Due to resonance stability and steric hindrance, the highly conjugated ketone radicals do not undergo A-stage polymerization, losing their initiation activity for monomers and participating in polymer chain bonding or seeding. Only free radicals from hydrogen donor compounds can initiate monomer polymerization.

[0088] In some embodiments, in the insulating coating ink, the mass percentage of the short- and medium-wave absorption initiator is P1, the mass percentage of the long-wave absorption initiator is P2, the mass percentage of the co-initiator is P3, the mass percentage of phthalocyanine blue is P4, the mass percentage of phthalocyanine green is P5, and the mass percentage of titanium dioxide is P6, satisfying the following:

[0089] P1+P2+P3=a×P4+b×P5-c×P6;

[0090] Where 4≤a≤6, 4≤b≤6, and 1≤c≤1.25.

[0091] Phthalocyanine blue and phthalocyanine green are strong light-absorbing pigments, which weaken the absorption efficiency of photoinitiators in specific wavelength bands. Titanium dioxide can enhance light penetration depth through reflection and scattering, but excessive titanium dioxide will reduce the system's transmittance. By ensuring that P1, P2, P3 and P4, P5, P6 satisfy the above formula, the mass percentage of the photoinitiator can be correlated with the type and content of pigments in the color powder. This compensates for the loss of absorption efficiency caused by phthalocyanine blue and phthalocyanine green, considers the light-transmitting enhancement effect of titanium dioxide, and avoids increased costs and reduced curing effect due to excessive addition of photoinitiator. In other words, this embodiment achieves a balance between photocuring effect and pigment hiding power by synergistically combining the amount of photoinitiator added with the type and amount of pigments in the color powder, resulting in an insulating coating with good heat resistance, weather resistance, abrasion resistance, and resistance to aging and yellowing.

[0092] For example, a can be 4, 4.5, 5, 5.5 or 6, b can be 4, 4.5, 5, 5.5 or 6, and c can be 1, 1.125 or 1.25.

[0093] In some embodiments, the primary initiator includes at least one of thioxanthone (TX), 2-chlorothioxanthone (CTX), 1-chloro-4-propoxythioxanthone (CPTX), isopropylthioxanthone (ITX), and 2,4-diethylthioxanthone (DETX).

[0094] Thioxanthone-based main initiators have strong absorption characteristics in the 350nm-450nm wavelength range, which can improve the utilization rate of light energy. They also have a long triplet lifetime, which can provide sufficient time for hydrogen transfer reactions and improve initiation efficiency.

[0095] In some embodiments, the co-initiator includes at least one selected from triethylamine, triethanolamine, methyldiethanolamine, N-methyldiethanolamine, ethyl-4-dimethylaminobenzoate, pentaerythritol, glycerol, polyethylene glycol, 1-octylthiol, trimethylolpropane tris(3-mercaptopropionate), and methyl 4-mercaptobenzoate.

[0096] The aforementioned co-initiators possess excellent hydrogen transfer performance and low-oxygen polymerization inhibition performance, ensuring hydrogen supply efficiency and initiation efficiency.

[0097] In some embodiments, the prepolymer in the insulating coating ink is 20%-50% by mass.

[0098] In some embodiments, the monomer content in the insulating coating ink is 30%-80% by mass.

[0099] The prepolymer's molecular structure contains a large number of polar groups, which can form a dense cross-linked network, ensuring the mechanical strength of the resulting insulating coating. The monomer has a dilution and cross-linking balance effect, which can reduce the viscosity of the insulating coating ink and participate in the cross-linking reaction.

[0100] In some embodiments, the insulating coating ink further includes additives, wherein the additives include color powder, and the mass percentage of the additives in the insulating coating ink is 0.2%-10%.

[0101] Additives, including colorants, help ensure the hiding power of the resulting insulating coating. Leveling agents, polymerization inhibitors, and other additives reduce surface defects, lower oxygen inhibition, and ensure proper curing. By keeping the mass percentage of additives within the aforementioned range, the quality of the resulting insulating coating can be improved.

[0102] For example, in the insulating coating ink, the mass percentage of prepolymer can be 20%, 25%, 30%, 35%, 40%, or 50%, the mass percentage of monomer can be 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or 80%, and the mass percentage of additives can be 0.2%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, or 10%.

[0103] In some embodiments, the prepolymer comprises bisphenol-type epoxy acrylate and polyester-based polyurethane acrylate. The mass ratio of bisphenol-type epoxy acrylate to polyester-based polyurethane acrylate is 1:(2-6).

[0104] Bisphenolic epoxy acrylates have a faster curing rate and excellent hardness and mechanical properties, while polyester-based polyurethane acrylates offer better flexibility and weather resistance, as well as good abrasion resistance and solvent resistance. By maintaining the mass ratio of bisphenolic epoxy acrylate to polyester-based polyurethane acrylate within the aforementioned range, insulation properties, mechanical strength, and flexibility can be balanced.

[0105] For example, the mass ratio of bisphenol-type epoxy acrylate to polyester-type polyurethane acrylate can be 1:2, 1:3, 1:4, 1:5 or 1:6.

[0106] In some embodiments, the molecular weight of the prepolymer is 1000 Da-2000 Da.

[0107] By setting the molecular weight of the prepolymer to 1000 Da-2000 Da, the viscosity of the insulating coating ink can be reduced, ensuring good curing efficiency and reducing the volume shrinkage rate after curing. Furthermore, the higher crosslinking density can improve the mechanical and chemical properties of the resulting insulating coating.

[0108] For example, the molecular weight of the prepolymer can be 1000Da, 1100Da, 1200Da, 1300Da, 1400Da, 1500Da, 1600Da, 1700Da, 1800Da, 1900Da or 2000Da.

[0109] In some embodiments, bisphenol-type epoxy acrylates include at least one of bisphenol A type epoxy acrylates, bisphenol S type epoxy acrylates, and bisphenol F type epoxy acrylates. The bisphenol-type epoxy acrylates can be obtained by polycondensation of bisphenol A, bisphenol S, or bisphenol F with epichlorohydrin.

[0110] In some embodiments, polyester polyurethane acrylates can be formed by polycondensation of a polyol and an isocyanate into hydroxyl-containing acrylates. The polyester polyol includes at least one selected from adipic acid-based polyester polyols, sebacic acid-based polyester polyols, terephthalic acid-based polyester polyols, and phthalic acid-based polyester polyols. The isocyanate includes at least one selected from isophorone diisocyanate (IPDI) and hexamethylene diisocyanate (HDI).

[0111] In some embodiments, the monomer includes at least two of the following: monofunctional acrylate monomers, difunctional acrylate monomers, and trifunctional acrylate monomers.

[0112] Among the monomers, the mass percentage of monofunctional acrylate monomers is 55%-85%, the mass percentage of difunctional acrylate monomers is 5%-25%, and the mass percentage of trifunctional acrylate monomers is 0%-20%.

[0113] Monofunctional acrylate monomers can control the curing speed and reduce stress, while difunctional and trifunctional acrylate monomers can improve crosslinking density and hardness. By keeping the mass percentages of monofunctional, difunctional, and trifunctional acrylate monomers within the above-mentioned ranges, it is possible to balance curing speed, mechanical properties, flexibility, shrinkage, and cost.

[0114] For example, in the monomers, the mass percentage of monofunctional acrylate monomers can be 55%, 60%, 65%, 70%, 75%, 80%, or 85%, the mass percentage of difunctional acrylate monomers can be 5%, 10%, 15%, 20%, or 25%, and the mass percentage of trifunctional acrylate monomers can be 0%, 5%, 10%, 15%, or 20%.

[0115] In some embodiments, the monofunctional acrylate monomer includes at least one of ethoxyethoxyacrylate, isoborneol acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and butyl acrylate.

[0116] The aforementioned monofunctional acrylate monomers exhibit good flexibility and weather resistance, and can improve adhesion.

[0117] In some embodiments, the bifunctional acrylate monomer includes at least one of dipropylene glycol diacrylate, tripropylene glycol diacrylate, 1,6-hexanediol diacrylate, and neopentyl glycol diacrylate.

[0118] The aforementioned bifunctional acrylate monomers have a fast curing speed and low shrinkage rate.

[0119] In some embodiments, the trifunctional acrylate monomer includes at least one of trimethylolpropane diacrylate, ethoxylated trimethylolpropane diacrylate, and pentaerythritol triacrylate.

[0120] The aforementioned trifunctional acrylate monomers can provide good hardness and impact resistance, and have low shrinkage properties.

[0121] In some embodiments, the additives include leveling agents, polymerization inhibitors, and color pastes; wherein the color pastes include color powder and color paste solvents. In insulating coating inks, the leveling agent comprises 0.2%-1.5% by mass.

[0122] In some embodiments, the polymer inhibitor in the insulating coating ink comprises 0.01%-0.5% by mass;

[0123] In some embodiments, the color paste in the insulating coating ink has a mass percentage of 0.2%-10%.

[0124] Leveling agents reduce the surface tension of insulating coating inks, helping to eliminate surface defects during the leveling process and ensuring the uniformity of the insulating coating. Polymer inhibitors suppress free radical polymerization, improving the stability of insulating coating inks during storage and regulating the curing speed. Color pastes provide color and meet hiding power requirements; by including the aforementioned color powders and solvents in the color paste, the color paste can be evenly dispersed in the insulating coating ink, ensuring stability.

[0125] For example, in the insulating coating ink, the mass percentage of the leveling agent can be 0.2%, 0.5%, 0.7%, 1%, 1.2%, or 1.5%, the mass percentage of the polymerization inhibitor can be 0.01%, 0.1%, 0.2%, 0.3%, 0.4%, or 0.5%, and the mass percentage of the color paste can be 0.2%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, or 10%.

[0126] In some embodiments, the leveling agent comprises a polyether-modified silicone leveling agent. Polyether-modified silicone leveling agents exhibit excellent leveling properties and good wetting properties, as well as good thermal stability, meeting the application requirements.

[0127] In some embodiments, the polymerization inhibitor includes hydroquinone. Hydroquinone is low in cost and has high polymerization inhibition efficiency.

[0128] In some embodiments, the particle size D50 of the insulating coating ink is ≤0.4μm.

[0129] By ensuring that the particle size D50 of the insulating coating is within the above-mentioned range, the density of the resulting insulating coating can be improved, the surface smoothness can be enhanced, good resistance to thermal aging and chemical corrosion can be guaranteed, and the long-term stability and reliability of the insulating coating can be improved.

[0130] For example, the preparation method of insulating coating ink includes: adding prepolymer, monomer, photoinitiator and additives into a double planetary mixer and dispersing them at 500r / min-1000r / min for 0.5h-1h to obtain insulating coating ink.

[0131] Thirdly, embodiments of this application provide a method for preparing an insulating coating, comprising:

[0132] The insulating coating ink described above is applied to the substrate surface to form a coating to be cured;

[0133] The coating to be cured is then cured to obtain an insulating coating.

[0134] The method for preparing the insulating coating provided in this application has all the beneficial effects of the insulating coating ink described above, and will not be repeated here.

[0135] In some embodiments, curing the coating to be cured includes:

[0136] Use an LED or electrodeless lamp to cure the coating for 1-8 seconds;

[0137] The LED light includes a first LED with a wavelength of 365nm and a second LED with a wavelength of 395nm.

[0138] By using LEDs or electrodeless lamps with two wavelengths, the wavelength response range of the insulating coating ink can be matched, ensuring the curing rate and curing effect, and improving the performance of the insulating coating.

[0139] Fourthly, embodiments of this application provide an insulating coating, including the insulating coating ink as described above, and / or prepared using the insulating coating preparation method described above.

[0140] The insulating coating provided in this application embodiment has all the beneficial effects of the insulating coating ink described above, which will not be repeated here.

[0141] In some embodiments, the thickness of the insulating coating is 60 μm-140 μm.

[0142] By keeping the thickness of the insulating coating within the above range, good insulation performance, mechanical strength and durability can be guaranteed, while achieving lightweighting and cost reduction.

[0143] For example, the thickness of the insulating coating can be 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm or 140μm.

[0144] The embodiments of this application are further illustrated below with reference to specific examples. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of this application. Experimental methods in the following embodiments that do not specify specific conditions are generally performed according to the conditions recommended by the manufacturer.

[0145] The formulations of the insulating coating inks in Examples 1-6 and Comparative Examples 1-2 are shown in Table 1:

[0146] Table 1. Formulation of insulating coating inks in Examples 1-6 and Comparative Examples 1-2

[0147]

[0148] In Table 1, A1 represents bisphenol-type epoxy acrylate, A2 represents polyester-type polyurethane acrylate, B1 represents monofunctional acrylate monomer, B2 represents difunctional acrylate monomer, B3 represents trifunctional acrylate monomer, C1 represents pyrolysis-type free radical photoinitiator, C11 represents short-to-medium wavelength absorption initiator, C12 represents long-wavelength absorption initiator, C2 represents hydrogen-abstracting free radical photoinitiator, D1 represents leveling agent, D2 represents polymerization inhibitor, D3 represents color paste, D31 represents color powder, D311 represents phthalocyanine blue, D312 represents phthalocyanine green, D313 represents titanium dioxide, and D32 represents color paste solvent.

[0149] Example 1

[0150] In this embodiment, A1 is bisphenol A type epoxy acrylate with a molecular weight of 1500 Da, A2 is adipic acid-based polyester polyurethane acrylate with a molecular weight of 1100 Da, B1 is ethoxyethoxyethyl acrylate, B2 is 1,6-hexanediol diacrylate, B3 is trimethylolpropane triacrylate, C11 is Irgacure 184, C12 is TPO, the main initiator in C2 is ITX, the co-initiator is triethylamine, the mass percentage of the co-initiator in C2 is 2%, D1 is polyether modified silicone leveling agent, and D2 is hydroquinone.

[0151] The method for preparing the insulating coating is as follows:

[0152] (1) Add each component to a double planetary mixer according to the proportions shown in Table 1, and disperse at a speed of 750 r / min for 0.75 h to obtain insulating coating ink;

[0153] (2) The insulating coating ink is sprayed onto the roughened battery casing and cured by electrodeless lamp for 5 seconds to form an insulating coating with a thickness of 100μm.

[0154] Example 2

[0155] In this embodiment, A1 is a bisphenol A type epoxy acrylate with a molecular weight of 1500 Da, A2 is an adipic acid-based polyester polyurethane acrylate with a molecular weight of 1100 Da, B1 is ethoxyethoxyethyl acrylate, B2 is 1,6-hexanediol diacrylate, B3 is trimethylolpropane triacrylate, C11 is Irgacure 184, C12 is Irgacure 907, the main initiator in C2 is ITX, the co-initiator is triethylamine, the mass percentage of the co-initiator in C2 is 2%, D1 is a polyether-modified silicone leveling agent, and D2 is hydroquinone.

[0156] The method for preparing the insulating coating is as follows:

[0157] (1) Add each component to a double planetary mixer according to the proportions shown in Table 1, and disperse at a speed of 750 r / min for 0.75 h to obtain insulating coating ink;

[0158] (2) The insulating coating ink is sprayed onto the roughened battery casing and cured by electrodeless lamp for 5 seconds to form an insulating coating with a thickness of 100μm.

[0159] Example 3

[0160] In this embodiment, A1 is a bisphenol A type epoxy acrylate with a molecular weight of 1500 Da, A2 is an adipic acid-based polyester polyurethane acrylate with a molecular weight of 1100 Da, B1 is ethoxyethoxyethyl acrylate, B2 is 1,6-hexanediol diacrylate, B3 is trimethylolpropane triacrylate, C11 is Irgacure 1173, C12 is Irgacure 369, the main initiator in C2 is DETX, the co-initiator is triethylamine, the mass percentage of the co-initiator in C2 is 2%, D1 is a polyether-modified silicone leveling agent, and D2 is hydroquinone.

[0161] The method for preparing the insulating coating is as follows:

[0162] (1) Add each component to a double planetary mixer according to the proportions shown in Table 1, and disperse at a speed of 750 r / min for 0.75 h to obtain insulating coating ink;

[0163] (2) The insulating coating ink is sprayed onto the roughened battery casing and cured by electrodeless lamp for 5 seconds to form an insulating coating with a thickness of 100μm.

[0164] Example 4

[0165] In this embodiment, A1 is bisphenol A type epoxy acrylate with a molecular weight of 1500 Da, A2 is adipic acid-based polyester polyurethane acrylate with a molecular weight of 1100 Da, B1 is ethoxyethoxyethyl acrylate, B2 is 1,6-hexanediol diacrylate, B3 is trimethylolpropane triacrylate, C11 is Irgacure 184, C12 is TPO, the main initiator in C2 is ITX, the co-initiator is triethylamine, the mass percentage of the co-initiator in C2 is 2%, D1 is polyether modified silicone leveling agent, and D2 is hydroquinone.

[0166] The method for preparing the insulating coating is as follows:

[0167] (1) Add each component to a double planetary mixer according to the proportions shown in Table 1, and disperse at a speed of 750 r / min for 0.75 h to obtain insulating coating ink;

[0168] (2) The insulating coating ink is sprayed onto the roughened battery casing and cured by electrodeless lamp for 5 seconds to form an insulating coating with a thickness of 100μm.

[0169] Example 5

[0170] In this embodiment, A1 is bisphenol A type epoxy acrylate with a molecular weight of 1500 Da, A2 is adipic acid-based polyester polyurethane acrylate with a molecular weight of 1100 Da, B1 is ethoxyethoxyethyl acrylate, B2 is 1,6-hexanediol diacrylate, B3 is trimethylolpropane triacrylate, C11 is Irgacure 184, C12 is TPO, the main initiator in C2 is ITX, the co-initiator is triethylamine, the mass percentage of the co-initiator in C2 is 2%, D1 is polyether modified silicone leveling agent, and D2 is hydroquinone.

[0171] The method for preparing the insulating coating is as follows:

[0172] (1) Add each component to a double planetary mixer according to the proportions shown in Table 1, and disperse at a speed of 750 r / min for 0.75 h to obtain insulating coating ink;

[0173] (2) The insulating coating ink is sprayed onto the roughened battery casing and cured for 5 seconds by LED with a wavelength of 365nm and LED with a wavelength of 395nm to form an insulating coating with a thickness of 100μm.

[0174] Example 6

[0175] In this embodiment, A1 is a bisphenol A type epoxy acrylate with a molecular weight of 1500 Da, A2 is an adipic acid-based polyester polyurethane acrylate with a molecular weight of 1100 Da, B1 is ethoxyethoxyethyl acrylate, B2 is 1,6-hexanediol diacrylate, B3 is trimethylolpropane triacrylate, C11 is Irgacure 641, C12 is Irgacure 819, the main initiator in C2 is TPO-L, the co-initiator is triethanolamine, the mass percentage of the co-initiator in C2 is 2%, D1 is a polyether-modified silicone leveling agent, and D2 is hydroquinone.

[0176] The method for preparing the insulating coating is as follows:

[0177] (1) Add each component to a double planetary mixer according to the proportions shown in Table 1, and disperse at a speed of 750 r / min for 0.75 h to obtain insulating coating ink;

[0178] (2) The insulating coating ink is sprayed onto the roughened battery casing and cured by electrodeless lamp for 5 seconds to form an insulating coating with a thickness of 100μm.

[0179] Comparative Example 1

[0180] In this embodiment, A1 is bisphenol A type epoxy acrylate with a molecular weight of 1500 Da, A2 is adipic acid-based polyester polyurethane acrylate with a molecular weight of 1100 Da, B1 is ethoxyethoxyethyl acrylate, B2 is 1,6-hexanediol diacrylate, B3 is trimethylolpropane triacrylate, C11 is Irgacure 184, D1 is polyether-modified silicone leveling agent, and D2 is hydroquinone.

[0181] The method for preparing the insulating coating is as follows:

[0182] (1) Add each component to a double planetary mixer according to the proportions shown in Table 1, and disperse at a speed of 750 r / min for 0.75 h to obtain insulating coating ink;

[0183] (2) The insulating coating ink is sprayed onto the roughened battery casing and cured by electrodeless lamp for 5 seconds to form an insulating coating with a thickness of 100μm.

[0184] Comparative Example 2

[0185] In this embodiment, A1 is bisphenol A type epoxy acrylate with a molecular weight of 1500 Da, A2 is adipic acid-based polyester polyurethane acrylate with a molecular weight of 1100 Da, B1 is ethoxyethoxyethyl acrylate, B2 is 1,6-hexanediol diacrylate, B3 is trimethylolpropane triacrylate, C11 is Irgacure 184, C12 is TPO, the main initiator in C2 is ITX, the co-initiator is triethylamine, the mass percentage of the co-initiator in C2 is 2%, D1 is polyether modified silicone leveling agent, and D2 is hydroquinone.

[0186] The method for preparing the insulating coating is as follows:

[0187] (1) Add each component to a double planetary mixer according to the proportions shown in Table 1, and disperse at a speed of 750 r / min for 0.75 h to obtain insulating coating ink;

[0188] (2) The insulating coating ink is sprayed onto the roughened battery casing and cured by electrodeless lamp for 5 seconds to form an insulating coating with a thickness of 100μm.

[0189] Comparative Example 3

[0190] In this comparative example, a PET blue film is used instead of an insulating coating.

[0191] The performance of the battery casings in Examples 1-6 and Comparative Examples 1-3 was tested respectively. The test content and methods are as follows:

[0192] (1) Curing speed test: The curing speed of the samples under different curing conditions was tested at 810 cm⁻¹. -1The infrared absorption of the characteristic peak at a certain point characterizes the extent of the curing reaction. Curing rate = (A0 - A...) t ) / (A0-A d )×100%, A0 is 810cm when uncured. -1 The intensity of the spectral band; A t The time t for ultraviolet light irradiation is 810 cm. -1 The intensity of the spectral band; A d 810 cm⁻¹ is required for complete curing (double bonds reduced to a minimum). -1 The intensity of the spectral band;

[0193] (2) Cross-cut adhesion test: Refer to GB / T 9286 2021 "Paints and Varnishes Cross-cut Adhesion Test";

[0194] (2) Shear strength test: Refer to GB / T 7124 2008 "Test of tensile shear strength of adhesives" (standard ≥10MPa);

[0195] (3) Insulation resistance test: Use an insulation withstand voltage tester, with conditions of DC1500V and a test time of 60s. The insulation resistance is ≥1GΩ.

[0196] (4) Withstand voltage test: Use an insulation withstand voltage tester, under the conditions of DC4000V, the test time is 60s, and the leakage current is ≤0.1mA;

[0197] (5) High temperature resistance test: The temperature is 130℃ and the time is 48h. Observe whether the coating shows abnormalities such as shrinkage, peeling, and cracking.

[0198] (6) Double 85 aging test conditions: Use a constant temperature and humidity chamber with a temperature of 85℃ and a relative humidity of 85% for a test time of 2000h. Observe whether the coating cracks or peels off, and test the voltage resistance, insulation and adhesion.

[0199] (7) Electrolyte resistance test: Immerse in D73 electrolyte for 48 hours at 25℃, remove and dry, and test voltage resistance, insulation and adhesion.

[0200] The test results are shown in Table 2:

[0201] Table 2 Comparison of performance test results in different embodiments and comparative examples

[0202]

[0203]

[0204] As can be seen from the comparison of Examples 1-6 and Comparative Example 1 in Table 2, the embodiments of this application, through the combination of pyrolysis-type free radical photoinitiators and hydrogen-abstracting free radical photoinitiators in the photoinitiator, and the pyrolysis-type free radical photoinitiators including short-wave and medium-wave absorption photoinitiators and long-wave absorption photoinitiators, can improve the efficiency and conversion rate of photoinitiators while meeting the requirements of the shielding power of the insulating coating, and improve the aging resistance and yellowing performance of the insulating coating (significantly improved performance in the double 85 aging resistance test).

[0205] As can be seen from the comparison between Examples 1-6 and Comparative Example 2 in Table 2, the embodiments of this application can significantly improve the shear strength by controlling the proportion of pigment and photoinitiator in the insulating coating ink, and the shear strength and voltage resistance remain in an excellent range after the double 85 aging test, which significantly improves the resistance to aging and yellowing compared to Comparative Example 2.

[0206] As can be seen from the comparison of Examples 1-6 and Comparative Example 3 in Table 2, compared with the traditional method of covering with blue film, the insulating coating formed by the insulating coating ink in the embodiments of this application has good high temperature resistance, which helps to achieve high temperature storage of batteries and improve safety.

[0207] As can be seen from the comparison between Examples 1-4 and Example 6 in Table 2, adjusting the type and proportion of photoinitiator will affect the absorption of ultraviolet light of different wavelengths by the photoinitiator. Adjusting the proportion of colored pigments (phthalocyanine blue, phthalocyanine green) and titanium dioxide in the color powder will affect the transmittance of the ink due to the reflection of titanium dioxide particles. Both of these factors limit the conversion rate of double bonds of unsaturated functional groups, which will in turn have a certain impact on the heat resistance, weather resistance, wear resistance and aging and yellowing resistance of the insulating coating.

[0208] The embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. An insulating coating ink, characterized in that, include: Prepolymer; monomer; The color powder includes at least two of phthalocyanine blue, phthalocyanine green and titanium dioxide, wherein the mass percentage of phthalocyanine blue is 60%-90%, the mass percentage of phthalocyanine green is 0%-30%, and the mass percentage of titanium dioxide is 10%-40%. The photoinitiator includes a cleavage-type free radical photoinitiator and a hydrogen-abstraction-type free radical photoinitiator; wherein the mass percentage of the cleavage-type free radical photoinitiator is 50%-90%, and the mass percentage of the hydrogen-abstraction-type free radical photoinitiator is 10%-50%; the cleavage-type free radical photoinitiator includes short- and medium-wavelength absorbing initiators and long-wavelength absorbing initiators, wherein the mass percentage of the short- and medium-wavelength absorbing initiator is 40%-70%, and the mass percentage of the long-wavelength absorbing initiator is 30%-60%; In the insulating coating ink, the photoinitiator has a mass percentage of 1%-5%, and the colorant has a mass percentage of 0.2%-1.5%.

2. The insulating coating ink according to claim 1, characterized in that, The absorption wavelength range of the short-to-medium wave absorption initiator is 200 nm to 340 nm; And / or, the absorption wavelength range of the long-wavelength absorption initiator is 310nm-450nm.

3. The insulating coating ink according to claim 1, characterized in that, The short and medium wave absorption initiator includes at least one of 1-hydroxycyclohexylphenyl ketone, benzoin dimethyl ether (benzoyl dimethyl ketal), and 2-hydroxy-2-methyl-1-phenyl-1-propanone; And / or, the long-wave absorption initiator includes at least one selected from 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, (2,4,6-trimethyl-3-benzoyl)benzoyl diphenylphosphine oxide, and 4-diethylaminobenzoyl diphenylphosphine oxide.

4. The insulating coating ink according to claim 1, characterized in that, The hydrogen-abstracting free radical photoinitiator includes a main initiator and a co-initiator; In the hydrogen-abstracting free radical photoinitiator, the mass percentage of the co-initiator is 0.5%-3%.

5. The insulating coating ink according to claim 4, characterized in that, In the insulating coating ink, the mass percentage of the short- and medium-wave absorption initiator is P1, the mass percentage of the long-wave absorption initiator is P2, the mass percentage of the co-initiator is P3, the mass percentage of phthalocyanine blue is P4, the mass percentage of phthalocyanine green is P5, and the mass percentage of titanium dioxide is P6, satisfying the following: P1+P2+P3=a×P4+b×P5-c×P6; Where 4≤a≤6, 4≤b≤6, and 1≤c≤1.

25.

6. The insulating coating ink according to claim 4, characterized in that, The main initiator includes at least one of thioxanthones, 2-chlorothioxanthones, 1-chloro-4-propoxythioxanthones, isopropylthioxanthones, and 2,4-diethylthioxanthones; The co-initiator includes at least one of triethylamine, triethanolamine, methyl diethanolamine, N-methyl diethanolamine, ethyl-4-dimethylaminobenzoate, pentaerythritol, glycerol, polyethylene glycol, 1-octylthiol, trimethylolpropane tris(3-mercaptopropionate), and methyl 4-mercaptobenzoate.

7. The insulating coating ink according to any one of claims 1-6, characterized in that, In the insulating coating ink, the prepolymer has a mass percentage of 20%-50%; And / or, in the insulating coating ink, the monomer has a mass percentage of 30%-80%.

8. The insulating coating ink according to any one of claims 1-6, characterized in that, The insulating coating ink further includes additives, wherein the additives include the color powder; In the insulating coating ink, the mass percentage of the additive is 0.2%-10%.

9. The insulating coating ink according to claim 1, characterized in that, The prepolymer includes bisphenol-type epoxy acrylate and polyester-based polyurethane acrylate; The mass ratio of the bisphenol type epoxy acrylate to the polyester polyurethane acrylate is 1:(2-6).

10. The insulating coating ink according to claim 1, characterized in that, The molecular weight of the prepolymer is 1000Da-2000Da.

11. The insulating coating ink according to claim 1, characterized in that, The monomers include at least two of the following: monofunctional acrylate monomers, difunctional acrylate monomers, and trifunctional acrylate monomers; In this monomer, the monofunctional acrylate monomer has a mass percentage of 55%-85%, the difunctional acrylate monomer has a mass percentage of 5%-25%, and the trifunctional acrylate monomer has a mass percentage of 0%-20%.

12. The insulating coating ink according to claim 11, characterized in that, The monofunctional acrylate monomer includes at least one of ethoxyethoxyacrylate, isoborneol acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and butyl acrylate. And / or, the bifunctional acrylate monomer includes at least one of dipropylene glycol diacrylate, ditripropylene glycol diacrylate, 1,6-hexanediol diacrylate and neopentyl glycol diacrylate. And / or, the trifunctional acrylate monomer includes at least one of trimethylolpropane diacrylate, ethoxylated trimethylolpropane diacrylate, and pentaerythritol triacrylate.

13. The insulating coating ink according to claim 8, characterized in that, The additives include leveling agents, polymerization inhibitors, and color pastes; wherein the color pastes include color powders and color paste solvents; In the insulating coating ink, the leveling agent comprises 0.2%-1.5% by mass. And / or, in the insulating coating ink, the polymerization inhibitor comprises 0.01%-0.5% by mass; And / or, in the insulating coating ink, the mass percentage of the color paste is 0.2%-10%.

14. The insulating coating ink according to claim 13, characterized in that, The leveling agent includes a polyether-modified silicone leveling agent; And / or, the polymerization inhibitor includes hydroquinone.

15. The insulating coating ink according to any one of claims 1-6, characterized in that, The particle size D50 of the insulating coating ink is ≤0.4μm.

16. A method for preparing an insulating coating, characterized in that, include: The insulating coating ink as described in any one of claims 1-15 is applied to the surface of a substrate to form a coating to be cured; The coating to be cured is then cured to obtain an insulating coating.

17. The method for preparing the insulating coating according to claim 16, characterized in that, The curing process of the coating to be cured includes: The coating to be cured is cured for 1-8 seconds using an LED or electrodeless lamp. The LED light includes a first LED with a wavelength of 365nm and a second LED with a wavelength of 395nm.

18. An insulating coating, characterized in that, It includes the insulating coating ink as described in any one of claims 1-15, and / or is prepared by the method for preparing the insulating coating as described in claim 16 or 17.

19. The insulating coating according to claim 18, characterized in that, The thickness of the insulating coating is 60μm-140μm.

20. A battery, characterized in that, Includes a housing, at least one surface of which is provided with an insulating coating as described in claim 18 or 19.

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