Antistatic, anti-adhesive and wear-resistant coating, and method for its production and use

Abstract

The application belongs to the technical field of heat-sensitive materials, and provides an antistatic, anti-adhesive and wear-resistant coating as well as a preparation method and application thereof. The application adopts water-based polyurea-poly 3,4-ethylenedioxythiophene conductive nanocomposite and water-based melamine formaldehyde resin-poly 3,4-ethylenedioxythiophene conductive composite microspheres as main raw material components of the coating. The coating prepared from the coating provided by the application has excellent and durable antistatic and anti-adhesive properties, can maintain the antistatic property in high-temperature and high-humidity and low-temperature and low-humidity environments, does not affect the optical property of the film, has high-efficiency anti-adhesive and wear-resistant properties, and has water resistance, can be further used for preparing heat-sensitive recording materials, and can run smoothly for a long time.

Description

Technical Field

[0001] This invention relates to the field of thermosensitive materials technology, and more specifically, to an antistatic, non-stick, and wear-resistant coating, its preparation method, and its application. Background Technology

[0002] In recent years, the application of thin film materials in packaging, printing, electronic displays, and medical devices has expanded rapidly. However, their surfaces are prone to static electricity accumulation and stickiness, leading to equipment malfunctions and even safety hazards. It is worth noting that in the process of medical imaging digitization, thermal medical films, as both thin film materials and thermal recording materials, have become an important carrier for diagnostic information output. Generally, thermal medical films have a thermal imaging layer and a protective layer coated on the front side of the substrate, and a back coating layer coated on the back side (to improve antistatic and anti-stick properties). However, in the actual high-speed mechanical operation of printing, the performance of the back coating layer, as the contact interface between the material and the printer's print roller, directly affects the reliability of imaging. For example, when the print roller peels a single sheet of medical film from the cartridge through friction, the back coating layer causes two key problems: first, a surge in frictional resistance between adjacent medical film layers (mainly due to static electricity and coating stickiness) leads to a "film-carrying" phenomenon, resulting in a chain of failures such as card and image misalignment; second, the back coating layer can be rubbed off due to the close contact and rubbing action of the print roller during high-speed operation, thus affecting the viewing effect of the printed image.

[0003] For example, Chinese patent (publication number CN112829490A) discloses a back coating of a thermal recording material, whose main components are water-based latex (or water-based resin) and polymethyl methacrylate (PMMA). However, it only considers the problem of coating stickiness, thus adding PMMA as a roughening agent (to form a micro-rough surface to reduce adhesion during film stacking and storage, and improve stability). But the coating uses water-based latex or resin, resulting in high coating stickiness, especially in high humidity environments, which easily leads to water absorption by the coating, causing adhesion during film stacking. In addition, since both water-based latex and PMMA are insulators, static electricity is easily generated in low to medium humidity environments (below 45%), causing adhesion and "film snagging" phenomenon. Furthermore, the back coating of the thermal recording material in Chinese patent (publication number CN112829490A) lacks abrasion resistance, causing the coating to peel off during film rubbing, affecting the viewing effect of the printed image.

[0004] To achieve antistatic effects, current back coatings primarily rely on the addition of inorganic salts or electrolytes as antistatic agents. However, these agents depend on ambient moisture to form a conductive water film, making them prone to adhesion at humidity levels above 60%, while low humidity (below 45%) reduces their antistatic effect. Conductive metal compounds or fillers, while less prone to water absorption, can lead to mechanical degradation (such as increased brittleness and coating cracking) and decreased light transmittance. Polymer antistatic agents, primarily poly(3,4-ethylenedioxythiophene) (PEDOT), are also available, but PEDOT's insoluble nature limits its application. Currently, PEDOT / PSS aqueous dispersions are mainly obtained by doping with water-soluble polymeric electrolyte polystyrene sulfonic acid (PSS) to solve the insolubility problem of PEDOT. However, PEDOT / PSS aqueous dispersions not only have low solid content (mostly around 3%, which is costly and limits their use), but also contain strong hydrophilic sulfonic acid groups (-SO3H) because PSS is an insulator (affecting the antistatic effect). This makes its conductivity still dependent on humidity. In low to medium humidity environments (below 45% RH), water stratification breaks down, ion migration is hindered, and surface resistance increases significantly, thus affecting the antistatic effect.

[0005] To achieve an anti-stick effect, fluorinated compounds or organosilicon materials are usually added to the back coating. Although this reduces surface energy, it leads to a decrease in film transmittance and requires the use of organic solvents, which pollute the environment and harm workers' health. Alternatively, adding a surface-texturing agent (to form a uniformly distributed micro-protrusion structure during the curing process) can achieve a certain anti-stick effect, but currently used surface-texturing agents are basically insulators, which greatly weakens the antistatic ability of the coating.

[0006] Therefore, the back coating of current thermal recording materials cannot simultaneously meet the requirements of durable antistatic properties, non-stick properties, and wear resistance. Thus, there is an urgent need to develop a back coating that combines durable antistatic properties, efficient non-stick properties, and wear resistance. Summary of the Invention

[0007] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes an antistatic, non-stick, and wear-resistant coating, its preparation method, and its application. The coating provided by this invention, when further prepared, exhibits stable and durable antistatic properties, maintaining these properties even in different usage environments (with a resistance reaching 10 ohms in both high-temperature, high-humidity (30℃ / 90%RH) and low-temperature, low-humidity (10℃ / 15%RH) environments). 7 -10 8It has high resistance (Ω, and the resistance remains unchanged after one month of storage), high efficiency in anti-sticking and wear resistance, as well as water resistance (withstanding more than 80 water friction cycles), and high light transmittance (haze 9-11%, light transmittance 79-80%). The coating can be further used as a back coating to prepare thermal recording materials (the film rate of thermal recording materials in high temperature and high humidity (30℃ / 90%RH) and low temperature and low humidity (10℃ / 15%RH) environments can be as low as 0-0.1%, and the back coating can achieve scratch-free operation), and can operate smoothly for a long time.

[0008] A first aspect of the present invention provides an antistatic, non-stick, and wear-resistant coating.

[0009] Specifically, an antistatic, non-stick, and wear-resistant coating comprises the following raw material components: Waterborne polyurea (PUA)-poly3,4-ethylenedioxythiophene (PEDOT) conductive nanocomposite material Waterborne melamine-formaldehyde resin (MF)-poly(3,4-ethylenedioxythiophene) (PEDOT) conductive composite microspheres.

[0010] This invention's coating utilizes a combination of waterborne polyurea (PUA)-poly3,4-ethylenedioxythiophene (PEDOT) conductive nanocomposite material and waterborne melamine-formaldehyde resin (MF)-poly3,4-ethylenedioxythiophene (PEDOT) conductive composite microspheres to improve the coating's antistatic, anti-stick, and abrasion resistance properties. The PUA-PEDOT conductive nanocomposite material possesses the conductivity of PEDOT, providing a long-lasting antistatic effect. It also exhibits good film-forming properties and high light transmittance (avoiding adverse effects on coating transparency). Furthermore, the flexibility and abrasion resistance of PUA contribute to enhancing the coating's abrasion resistance. The MF-PEDOT conductive composite microspheres combine the abrasion resistance of MF with the conductivity of PEDOT, providing long-lasting antistatic properties while also acting as a surface roughener (which provides an anti-stick effect). This creates a micro-rough structure on the coating surface, effectively reducing adhesion during film stacking and storage. It also possesses antistatic properties and solves the problem of conventional surface rougheners being insulators, further enhancing the coating's antistatic and anti-stick properties. Therefore, the coating obtained by further processing the coating of the present invention can achieve a long-lasting antistatic effect, while also having excellent anti-stick and wear-resistant effects.

[0011] Preferably, the coating comprises the following raw material components in parts by weight: 20-40 parts of waterborne polyurea-poly3,4-ethylenedioxythiophene (PUA-PEDOT) conductive nanocomposite material 1-10 parts of waterborne melamine-formaldehyde resin-poly(3,4-ethylenedioxythiophene) (MF-EDOT) conductive composite microspheres.

[0012] More preferably, the coating comprises the following raw material components in parts by weight: 30-40 parts of waterborne polyurea-poly3,4-ethylenedioxythiophene (PUA-PEDOT) conductive nanocomposite material 5-10 parts of waterborne melamine-formaldehyde resin-poly(3,4-ethylenedioxythiophene) (MF-EDOT) conductive composite microspheres.

[0013] Preferably, the aqueous polyurea (PUA)-poly3,4-ethylenedioxythiophene (PEDOT) conductive nanocomposite material has a core-shell structure, where the core is polyurea and the shell is poly3,4-ethylenedioxythiophene. Both PUA and PEDOT have high light transmittance; therefore, the core-shell structure PUA-PEDOT conductive nanocomposite material exhibits high light transmittance without affecting the film's transmittance. Furthermore, PEDOT, acting as the shell, stably aggregates on the core surface, avoiding migration issues. PEDOT forms a stable conductive network through its conjugated π-electron system, effectively dispersing static charge and suppressing static accumulation. The chemical stability of the core-shell structure ensures the integrity of the conductive path during long-term use, helping to prevent performance degradation due to changes in environmental humidity or temperature. Therefore, it contributes to maintaining a long-lasting antistatic effect, unaffected by environmental humidity.

[0014] Preferably, the particle size Dv90 of the waterborne polyurea (PUA)-poly3,4-ethylenedioxythiophene (PEDOT) conductive nanocomposite is 1-5 μm.

[0015] Preferably, the waterborne melamine-formaldehyde resin (MF)-poly3,4-ethylenedioxythiophene (PEDOT) conductive composite microspheres have a core-shell structure, wherein the core is melamine-formaldehyde resin and the shell is poly3,4-ethylenedioxythiophene. The MF core helps to form a micro-rough surface on the coating surface, effectively reducing adhesion during film stacking and storage, and improving stability. It mainly acts as a surface roughening agent. However, as an insulator, it is prone to static electricity accumulation, causing adhesion and leading to "sheet-like" phenomena. This invention solves the problem of traditional surface roughening agents being insulators by polymerizing a conductive PEDOT shell on its surface.

[0016] Preferably, the particle size Dv90 of the waterborne melamine-formaldehyde resin (MF)-poly(3,4-ethylenedioxythiophene) (PEDOT) conductive composite microspheres is 10-20 μm.

[0017] Preferably, the raw material components of the coating further include an adhesive and a crosslinking agent; The crosslinking agent includes a first crosslinking agent and a second crosslinking agent, wherein the first crosslinking agent is at least one of isocyanate crosslinking agents, aziridine crosslinking agents, and organosilicon crosslinking agents, and the second crosslinking agent is at least one of aldehyde crosslinking agents, organometallic crosslinking agents, and organic acid crosslinking agents; The adhesive includes a first adhesive and a second adhesive. The first adhesive is at least one of waterborne polyurethane emulsion resin, waterborne acrylic emulsion resin, waterborne styrene-acrylic emulsion resin, and waterborne fluorocarbon emulsion resin. The second adhesive is at least one of carboxyl-modified polyvinyl alcohol (such as carboxyl-modified polyvinyl alcohol of model PVA224 produced by Kuraray, Japan), acetyl-modified polyvinyl alcohol (such as acetyl-modified polyvinyl alcohol of model PVA217 produced by Kuraray, Japan), and acetoacetyl-modified polyvinyl alcohol (such as acetoacetyl-modified polyvinyl alcohol of model Z100 produced by Kashinri Manshi Co., Ltd.).

[0018] This invention employs two different adhesives to facilitate the formation of a continuous coating structure. These adhesives primarily function to bond the various raw material components, improve the coating's abrasion resistance, and enhance the adhesion between the coating and the substrate. This ensures that the components are tightly bound and not easily separated, and that the coating adheres more firmly to the substrate surface, enhancing the coating's mechanical properties and weather resistance, and guaranteeing long-term stability of the coating performance. Furthermore, the adhesives exhibit low tackiness (as manifested by the substances themselves) after subsequent drying, and after further cross-linking and curing with a cross-linking agent, there is virtually no stickiness. Specifically, the first adhesive forms a continuous polymer film through water evaporation, firmly adhering the coating material to the substrate surface while providing flexibility and weather resistance. The second adhesive forms a hydrogen bond network through hydroxyl groups, improving the coating's mechanical strength and water resistance. By using the two adhesives in combination, the flexibility provided by the first adhesive and the rigidity provided by the second adhesive are combined, balancing the coating's flexibility and strength. Additionally, the second adhesive can adjust the viscosity, improving application flowability. This invention employs two different crosslinking agents. The first crosslinking agent primarily further crosslinks and cures the first adhesive in the coating, while the second crosslinking agent primarily crosslinks and cures the second adhesive in the coating, jointly improving the coating's wear resistance and water resistance. Furthermore, the coating of this invention is a water-based formulation, thus also offering environmental advantages.

[0019] Preferably, the coating comprises, by weight, 15-30 parts of a first adhesive, 5-20 parts of a second adhesive, 1-5 parts of a first crosslinking agent, and 1-5 parts of a second crosslinking agent.

[0020] More preferably, the coating comprises, by weight, 20-30 parts of a first adhesive, 10-20 parts of a second adhesive, 2-4 parts of a first crosslinking agent, and 2-4 parts of a second crosslinking agent.

[0021] Preferably, the first crosslinking agent is an isocyanate crosslinking agent.

[0022] Preferably, the isocyanate crosslinking agent is a aziridine-modified isocyanate crosslinking agent.

[0023] Preferably, the second crosslinking agent is an organometallic crosslinking agent.

[0024] Preferably, the organometallic crosslinking agent is an organozirconium crosslinking agent.

[0025] More preferably, the first crosslinking agent is an aziridine-modified isocyanate crosslinking agent, and the second crosslinking agent is an organozirconium crosslinking agent. The organozirconium crosslinking agent is a zirconium chelate (a delayed crosslinking agent with a curing temperature greater than 50°C), which can chelate with -OH or -COOH groups to form a crosslinking network, further improving the coating's water resistance. The organozirconium crosslinking agent can react with water to hydrolyze and form a chelate, which can delay the side reactions between the aziridine-modified isocyanate crosslinking agent and water. During the high-temperature (greater than 50°C) drying and curing process of the coating, the organozirconium crosslinking agent can also catalyze the rapid crosslinking and curing of the aziridine-modified isocyanate crosslinking agent. Therefore, both crosslinking agents work together to promote coating crosslinking and improve the coating's wear resistance and water resistance.

[0026] Preferably, the first adhesive is an aqueous fluorocarbon emulsion resin. Aqueous fluorocarbon emulsion resins have low surface energy (surface tension less than 20 mN / m), which makes the coating surface hydrophobic, and also have strong weather resistance (the FC bonds in the fluorocarbon resin resist ultraviolet degradation) and excellent anti-sticking effect.

[0027] Preferably, the second adhesive is acetyl-modified polyvinyl alcohol.

[0028] Preferably, the raw material components of the coating further include at least one of lubricant I, adhesion improver, wetting and leveling agent I, and thickener.

[0029] More preferably, the raw material components of the coating further include lubricant I, adhesion improver, wetting and leveling agent I, and thickener.

[0030] More preferably, the raw material components of the coating, by weight, further include 5-15 parts of lubricant I, 1-5 parts of adhesion improver, 1-5 parts of wetting and leveling agent I, and 1-10 parts of thickener.

[0031] More preferably, the raw material components of the coating, by weight, further include 10-15 parts of lubricant I, 3-5 parts of adhesion improver, 3-5 parts of wetting and leveling agent I, and 5-10 parts of thickener.

[0032] Preferably, the lubricant I is an organosilicon surfactant-type lubricant and / or a wax-based lubricant.

[0033] More preferably, the lubricant I is an organosilicon surfactant-type lubricant and a wax-based lubricant.

[0034] Preferably, the organosilicon surfactant-type lubricant is a polyether-modified silicone oil.

[0035] Preferably, the wax lubricant is a modified paraffin emulsion.

[0036] More preferably, the lubricant I is a polyether-modified silicone oil and a modified paraffin emulsion.

[0037] Polyether-modified silicone oil, with its low surface tension (approximately 21 mN / m), combined with modified paraffin emulsions of medium to low melting points (30-50℃), can form a gradient lubricating film over a wide temperature range (-30℃ to 50℃). Through dynamic lubrication complementarity, the polyether-modified silicone oil provides instantaneous lubrication, while the modified paraffin emulsion continuously releases lubrication at room temperature. It also enhances anti-migration properties (the linear modified structure of the siloxane chains forms a physical cross-link with the crystalline network of the wax, reducing lubricant precipitation) and extends service life. Therefore, the combined use of polyether-modified silicone oil and modified paraffin emulsion can further improve the anti-sticking and wear-resistant properties of the coating.

[0038] Preferably, the adhesion improver is an aqueous silane oligomer. Aqueous silane oligomers can effectively improve the adhesion of the coating to the substrate, further enhancing the coating's wear resistance.

[0039] Preferably, the raw material components of the coating also include water.

[0040] A second aspect of the present invention provides a method for preparing a coating.

[0041] A method for preparing a coating includes the following steps: The coating is prepared by mixing the various raw material components.

[0042] Preferably, the aqueous polyurea (PUA)-poly3,4-ethylenedioxythiophene (PEDOT) conductive nanocomposite material is prepared by a method comprising the following steps: Under the action of a first oxidant, a first catalyst and a first dopant, the polyurea dispersion and the 3,4-ethylenedioxythiophene monomer are subjected to a first in-situ polymerization reaction to obtain the waterborne polyurea (PUA)-poly3,4-ethylenedioxythiophene (PEDOT) conductive nanocomposite material.

[0043] During the polymerization reaction, 3,4-ethylenedioxythiophene monomers form PEDOT (shell) in situ on the surface of polyurea particles (PUA) (core), thus obtaining a core-shell structured aqueous PUA-PEDOT conductive nanocomposite material.

[0044] More preferably, the waterborne polyurea (PUA)-poly3,4-ethylenedioxythiophene (PEDOT) conductive nanocomposite material is prepared by a method comprising the following steps: First, the first oxidant, the first catalyst, and water are mixed and added to the polyurea dispersion. After heating to 40-60°C, a mixture of 3,4-ethylenedioxythiophene monomer and the first organic solvent, and the first dopant are added sequentially. Through the first in-situ polymerization reaction, the waterborne polyurea (PUA)-poly3,4-ethylenedioxythiophene (PEDOT) conductive nanocomposite material is obtained.

[0045] Preferably, the temperature of the first in-situ polymerization reaction is 40-60°C, and / or the time of the first in-situ polymerization reaction is 20-48 h.

[0046] Preferably, the aqueous melamine-formaldehyde resin (MF)-poly3,4-ethylenedioxythiophene (PEDOT) conductive composite microspheres are prepared by a method comprising the following steps: Under the action of a second oxidant, a second catalyst, and a second dopant, melamine-formaldehyde resin microcapsules and 3,4-ethylenedioxythiophene monomer are subjected to a second in-situ polymerization reaction to obtain the aqueous melamine-formaldehyde resin (MF)-poly3,4-ethylenedioxythiophene (PEDOT) conductive composite microspheres.

[0047] More preferably, the waterborne melamine-formaldehyde resin-poly3,4-ethylenedioxythiophene (MF-PEDOT) conductive composite microspheres are prepared by a method comprising the following steps: First, the second oxidant, the second catalyst, and water are mixed, and then melamine-formaldehyde resin microcapsules (water-based melamine resin microcapsules) are added. After heating to 40-60℃, a mixture of 3,4-ethylenedioxythiophene monomer and the second organic solvent, and the second dopant are added sequentially. Through the second in-situ polymerization reaction, the water-based melamine-formaldehyde resin (MF)-poly3,4-ethylenedioxythiophene (PEDOT) conductive composite microspheres are obtained.

[0048] Preferably, the first organic solvent and the second organic solvent are each independently selected from at least one of methanol, ethanol, and propanol.

[0049] Preferably, the first oxidant and the second oxidant are each independently selected from at least one of sodium persulfate (Na2S2O8), ammonium persulfate, and ferric perchlorate (Fe(ClO4)3).

[0050] More preferably, both the first oxidant and the second oxidant are sodium persulfate (Na2S2O8).

[0051] Preferably, the first catalyst and the second catalyst are each independently selected from at least one of ferric p-toluenesulfonate (Fe(OTs)3), ferric chloride, and ferric sulfate.

[0052] Preferably, both the first catalyst and the second catalyst are iron p-toluenesulfonate (Fe(OTs)3).

[0053] The alkyl hydrophobic segments of ferric p-toluenesulfonate tend to approach the PUA latex particles or MF microcapsules, while the sulfonic acid hydrophilic groups are dispersed in the aqueous phase. Therefore, due to the dispersibility of ferric p-toluenesulfonate and the hydrophobicity of 3,4-ethylenedioxythiophene (EDOT) monomer, the EDOT monomer tends to approach the surface of the PUA latex particles or the surface of the MF microcapsules. Under the action of oxidants and catalysts, an in-situ polymerization reaction occurs, generating a core-shell structured aqueous PUA-PEDOT conductive nanocomposite material or an aqueous MF-PEDOT conductive composite microsphere.

[0054] Preferably, the first dopant and the second dopant are each independently selected from imidazole ionic liquids and / or hydroquinone derivatives (such as 3,4-dihydroxybenzoyl hydrazine (DOBD)).

[0055] Preferably, the imidazole ionic liquids are all 1-ethyl-3-methylimidazolium sulfate ethyl salt (EMIM[ESO4]). The 1-ethyl-3-methylimidazolium cation ([EMIM]) in 1-ethyl-3-methylimidazolium sulfate ethyl salt... + By forming hydrogen bonds with sulfur atoms (in the thiophene ring) on ​​the PEDOT chain through hydrogen bonding, the π-π stacking between PEDOT chains is disrupted, and excessive aggregation is inhibited, thereby promoting the stable polymerization of PEDOT on the surface of PUA latex particles, thus enhancing the conductivity and stability of the PUA (core)-PEDOT (shell) conductive nanocomposite material.

[0056] The PUA-PEDOT conductive nanocomposite material and MF-PEDOT conductive composite microspheres used in this invention are both formed by the stable polymerization of EDOT monomers into PEDOT and their aggregation on the surface of the core (PUA or MF). In the polymerization process, dopants are also used as auxiliaries to effectively prevent the excessive aggregation of PEDOT molecular chains. The resulting polymers and microspheres are both micron-sized. Micron-sized materials have good compatibility with water-based coating systems, thus overcoming the limitation that PEDOT itself is an insoluble polymer and broadening its application range.

[0057] A third aspect of the present invention provides a coating.

[0058] A coating prepared using the above-mentioned paint.

[0059] A fourth aspect of the present invention provides a thermal recording material.

[0060] A thermal recording material comprises, in sequence, a protective layer, a thermal imaging layer, a substrate, and a back coating layer, wherein the back coating layer is prepared using the coating material.

[0061] Preferably, the thermal imaging layer is obtained by coating with a thermal imaging layer coating liquid.

[0062] Preferably, the thermal imaging layer coating liquid comprises the following components: colorless dye dispersion, color developer dispersion, third adhesive, nanofiller, wetting agent, and defoamer I.

[0063] Preferably, the colorless dye dispersion comprises the following raw material components: polyvinyl alcohol, colorless dye, and water.

[0064] Preferably, the color developer dispersion comprises the following raw material components: polyvinyl alcohol, color developer, defoamer II, and water.

[0065] Preferably, the color developer is at least one of 2,4-diphenylsulfone phenol, 4,4'-sulfonylbis[2-(2-propenyl)]phenol, 4-hydroxy-4'-isopropoxydiphenylsulfone, benzyl p-hydroxybenzoate, and p-hydroxybenzoate.

[0066] Preferably, the defoamer I and defoamer II are each independently selected from at least one of water-based non-silicone defoamers (such as BYK011 from BYK Chemical), mineral oil defoamers, modified silicone oil defoamers, and polyether defoamers.

[0067] Preferably, the third adhesive is at least one of waterborne acrylic latex resin, waterborne polyurethane latex resin, waterborne polyurethane-acrylic hybrid latex resin, and waterborne styrene-acrylic latex resin.

[0068] Preferably, the nanofiller is at least one of silicon dioxide, kaolin, and aluminum hydroxide.

[0069] Preferably, the wetting agent is at least one of the following: an organosilicon surface wetting agent (such as BYK326 from BYK Chemical), a fluorinated surface wetting agent, and an acetylenic diol surface wetting agent.

[0070] More preferably, the thermal imaging layer coating liquid comprises, by weight, the following components: 30-50 parts colorless dye dispersion, 20-30 parts color developer dispersion, 5-15 parts third adhesive, 1-15 parts nanofiller, 0.5-2 parts wetting agent, and 0.5-2 parts defoamer.

[0071] Preferably, the thermal imaging layer coating liquid further includes water.

[0072] Preferably, the protective layer is obtained by applying a protective layer coating liquid.

[0073] Preferably, the protective coating liquid comprises the following components: Polyvinyl alcohol, fillers, lubricant II, wetting and leveling agent II, and ultraviolet absorber.

[0074] More preferably, the protective coating liquid comprises the following components: Polyvinyl alcohol 50-60 parts, filler 10-20 parts, lubricant II 5-10 parts, wetting and leveling agent II 5-10 parts, ultraviolet absorber 5-10 parts.

[0075] Preferably, the filler is at least one selected from silicon dioxide, calcined kaolin, cerium oxide, aluminum hydroxide, and calcium carbonate.

[0076] Preferably, the lubricant II is at least one of polyethylene wax emulsion, modified paraffin wax, and carnauba wax.

[0077] Preferably, the wetting and leveling agent II is at least one of fluorine-containing surface wetting and leveling agents, organosilicon surface wetting and leveling agents (polysiloxane wetting and leveling agents), and acetylenic diol surface wetting and leveling agents.

[0078] Preferably, the ultraviolet absorber is a benzotriazole ultraviolet absorber, a benzophenone ultraviolet absorber, a salicylate ultraviolet absorber, a triazine ultraviolet absorber, or a benzimidazole sulfonic acid ultraviolet absorber.

[0079] Preferably, the substrate is a paper-based substrate and / or a plastic substrate.

[0080] More preferably, the plastic substrate is at least one of polyethylene terephthalate (PET), polyethylene (PE), polyvinyl chloride (PVC), polystyrene (PS), and polypropylene (PP).

[0081] Preferably, the protective coating liquid further includes water.

[0082] The fifth aspect of the present invention provides a method for preparing a thermal recording material.

[0083] A method for preparing a thermal recording material includes the following steps: The coating is applied to one side of the substrate to obtain a back coating. A thermal imaging layer coating liquid and a protective layer coating liquid are applied sequentially to the other side of the substrate to obtain a thermal imaging layer and a protective layer, respectively, thus obtaining the thermal recording material.

[0084] Preferably, the method for preparing the thermal recording material includes the following steps: First, the coating is applied to one side of the substrate and dried to obtain a back coating. Then, a thermal imaging layer coating liquid is applied to the other side of the substrate and dried to obtain a thermal imaging layer. Next, a protective layer coating liquid is applied and dried to obtain a protective layer, thus obtaining the thermal recording material.

[0085] Preferably, the temperature of the first drying is 100-120°C, and / or the drying time is 10-15 min.

[0086] Preferably, the temperature of the second drying is 40-80°C, and / or the drying time is 10-15 min.

[0087] Preferably, the temperature of the third drying is 40-80°C, and / or the time of the third drying is 10-15 minutes.

[0088] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention uses waterborne polyurea-poly3,4-ethylenedioxythiophene conductive nanocomposite material and waterborne melamine-formaldehyde resin-poly3,4-ethylenedioxythiophene conductive composite microspheres as the main raw material components of the coating. The coating obtained by further processing the coating provided by this invention has excellent and durable antistatic properties (the resistance can reach 10 ohms in both high temperature and high humidity (30℃ / 90%RH) and low temperature and low humidity (10℃ / 15%RH) environments). 7 -10 8 It has high resistance (Ω, and the resistance remains unchanged after one month of storage) and anti-stick properties, and does not affect the optical properties of the film (haze 9-11%, transmittance 79-80%). It also has abrasion resistance and water resistance (resistant to more than 80 water friction cycles). It can be further used to prepare thermal recording materials (the film rate of thermal recording materials in high temperature and high humidity (30℃ / 90%RH) and low temperature and low humidity (10℃ / 15%RH) environments is as low as 0-0.1%, and the back coating can achieve a scratch-free effect). It can operate smoothly for a long time, especially as a thermal medical film. Detailed Implementation

[0089] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0090] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0091] Example 1 A method for preparing an antistatic, non-stick, and wear-resistant coating includes the following steps: 1. Preparation of polyurea (PUA) prepolymer: Sixteen parts of polytetrahydrofuran ether glycol (PTMG 2000, BASF, Germany) were vacuum dehydrated at 130°C and 0.01 MPa for 1-2 hours. The solution was then dissolved in 54 parts of acetone to reduce viscosity. After stirring at room temperature, a polytetrahydrofuran glycol solution was obtained, and the temperature was subsequently raised to 80°C. Thirty parts of isophorone diisocyanate (IPDI, Wanhua Chemical) were added to the above solution, and one part of dibutyltin dilaurate (catalyst, Shanghai Macklin) was added dropwise. The reaction was maintained at 100°C for 2 hours to obtain a polyurea prepolymer.

[0092] 2. Preparation of polyurea (PUA) dispersions: Under a mechanical stirrer, thermometer, and nitrogen atmosphere, 70 parts of polyurea prepolymer and 20 parts of HDI trimer (hexamethylene diisocyanate trimer, HT100, Wanhua Chemical) were added to a reactor and stirred at 80°C. Then, 10 parts of tetraethylenepentamine (Shanghai Macklin) were introduced into the mixture and maintained for 3 hours. Finally, the mixture was cooled to room temperature and dispersed in deionized water at a high stirring speed to obtain a polyurea dispersion with a solids content of 30%.

[0093] 3. Preparation of PUA-PEDOT conductive nanocomposite material (PUA-PEDOT dispersion): Five parts of sodium persulfate (Na2S2O8, Xilong Chemical) and five parts of ferric tritoluenesulfonate (Fe(OTs)3, Shanghai Macklin) were added to a reactor and dissolved in deionized water. Then, 70 parts of PUA dispersion were added under stirring at room temperature. After heating to 50°C, 15 parts of a mixed solution of EDOT (Suzhou Yake Technology Co., Ltd.) / methanol (Shanghai Macklin) (EDOT / methanol mass ratio of 1 / 2) were added, followed by five parts of ethyl 1-ethyl-3-methylimidazolium sulfate (EMIES, Hubei Jiahuixingcheng Biotechnology Co., Ltd.). The mixture was magnetically stirred for 24 hours to obtain a PUA-PEDOT dispersion with a particle size Dv90 = 1.5 μm and a solid content of 20%.

[0094] 4. Preparation of waterborne melamine resin microcapsules (MF capsules): Ten parts of Tween 80 (Merck Life Sciences), ten parts of Span 80 (Merck Life Sciences), and 30 parts of deionized water were added to a reactor. The mixture was mechanically stirred to form a compound emulsifier. After stirring for 30 minutes, the pH of the system was adjusted to 4-5 with two parts of 20% citric acid aqueous solution. Then, 48 parts of the melamine-formaldehyde resin prepolymer (Anhui Haihong Chemical Co., Ltd.) prepared above were slowly added, and the reaction was maintained at 85°C for 4 hours to obtain waterborne melamine resin microcapsules (MF capsules) with a particle size Dv90=13μm and a solid content of 30%.

[0095] 5. Preparation of MF-PEDOT conductive composite microspheres (MF-PEDOT microspheres): Five parts of sodium persulfate (Na2S2O8, Xilong Chemical) and five parts of ferric tritoluenesulfonate (Fe(OTs)3, Shanghai Maclean) were added to a reactor and dissolved in deionized water. Then, 70 parts of MF capsules were added under stirring at room temperature. After heating to 50°C, 15 parts of an EDOT / methanol mixed solution (EDOT / methanol mass ratio of 1 / 2) were added, followed by five parts of ethyl 1-ethyl-3-methylimidazolium sulfate (EMIES), an effective dopant. The reaction was magnetically stirred for 24 hours to obtain MF-PEDOT microspheres with a particle size Dv90 = 15 μm. After multiple washing and drying, MF-PEDOT microsphere powder was obtained.

[0096] 6. Preparation of antistatic, anti-stick, and wear-resistant coatings (back coating liquid): Add 30 parts of PUA-PEDOT dispersion, 25 parts of waterborne fluorocarbon emulsion resin (first adhesive, F13-0801, Shenzhen Yoshida Chemical Co., Ltd.), 10 parts of polyvinyl alcohol Z100 cooking liquor (second adhesive, Gaoxianli Wanshi Co., Ltd., Z100), 5 parts of modified paraffin emulsion (lubricant, Japan Chukyo Yushi R-232), 5 parts of polyether modified silicone oil (lubricant, P875564, Shanghai Macklin), 3 parts of adhesion improver (KRN7000, Jinrunna), and 3 parts of wetting and leveling agent (BYK333, BYK Chemical) to the reactor, mix, and homogenize for 10 min. Then add ammonia water to adjust the pH to 9-10, add 5 parts of thickener (PR-9380, Dow Chemical), and homogenize for another 40 min to form a uniform pre-dispersion mixture. After mixing and dispersing 5 parts of MF-PEDOT microsphere powder with 5 parts of anhydrous ethanol evenly, the mixture was added to the above-mentioned pre-dispersed solution to obtain a pre-dispersed solution. The temperature of the mixed dispersion was then increased to 35°C, and 2 parts of aziridine-modified isocyanate crosslinking agent (first crosslinking agent, C63, Guangzhou Wanjun Chemical Technology Co., Ltd.) and 2 parts of organozirconium crosslinking agent (second crosslinking agent, Tyzor 212, Guangzhou Wanjun Chemical Technology Co., Ltd.) were slowly added. The mixture was homogenized and stirred for 1 hour, and then diluted with deionized water to a solid content of 5% for the back coating solution. The back coating solution was allowed to stand for 24 hours, and no obvious stratification or precipitation was observed.

[0097] Example 2 A method for preparing an antistatic, non-stick, and wear-resistant coating differs from Example 1 in that 70 parts of PUA dispersion in step 3 are replaced with 60 parts of PUA dispersion, and 15 parts of EDOT in step 3 are replaced with 25 parts of EDOT.

[0098] Example 3 A method for preparing an antistatic, non-stick, and wear-resistant coating differs from Example 1 in that 70 parts of MF capsules in step 5 are replaced with 65 parts of MF capsules, and 15 parts of EDOT are replaced with 20 parts of EDOT.

[0099] Example 4 A method for preparing an antistatic, non-stick, and wear-resistant coating differs from Example 1 in that 25 parts of waterborne fluorocarbon emulsion resin (first adhesive) and 10 parts of polyvinyl alcohol Z100 cooking liquor (second adhesive) in step 6 are replaced with 20 parts of waterborne fluorocarbon emulsion resin (first adhesive) and 15 parts of polyvinyl alcohol Z100 cooking liquor (second adhesive), respectively.

[0100] Example 5 A method for preparing a coating differs from Example 1 in that the waterborne fluorocarbon emulsion resin (first adhesive) in step 6 is replaced with an equal part by weight of waterborne polyurethane emulsion resin (first adhesive, Wanhua Chemical 4221).

[0101] Example 6 A method for preparing a coating differs from Example 1 in that modified paraffin emulsion (lubricant) is not added in step 6.

[0102] Example 7 A method for preparing a coating differs from Example 1 in that polyether-modified silicone oil (lubricant) is not added in step 6.

[0103] Example 8 A method for preparing a coating differs from Example 1 in that, in step 6, an aziridine-modified isocyanate crosslinking agent (first crosslinking agent) is not added.

[0104] Example 9 A method for preparing a coating differs from Example 1 in that an organozirconium crosslinking agent (second crosslinking agent) is not added in step 6.

[0105] Comparative Example 1 A method for preparing a coating differs from Example 1 in that the PUA-PEDOT dispersion in step 6 is replaced with an equal weight of PUA dispersion (i.e., the PUA dispersion obtained in step 2 of Example 1).

[0106] Comparative Example 2 A method for preparing a coating differs from Example 1 in that the MF-PEDOT microsphere powder in step 6 is replaced with an equal weight of MF capsules (i.e., the MF capsules obtained in step 4 of Example 1).

[0107] Comparative Example 3 A method for preparing a coating differs from Example 1 in that the PUA-PEDOT dispersion in step 6 is replaced with an equal weight of conductive nanocomposite material PEDOT / PSS dispersion (Shenzhen Yilai Technology Co., Ltd. PH1000).

[0108] Comparative Example 4 A method for preparing a coating differs from Example 1 in that the MF-PEDOT microsphere powder in step 6 is replaced with an equal part by weight of polymethyl methacrylate (PMMA) microsphere powder (Sekisui, Japan, MBX-8).

[0109] Application Example 1 A method for preparing a thermal recording material includes the following steps: 1. Preparation of thermal imaging layer coating solution: 50 parts of colorless dye dispersion, 30 parts of color developer dispersion, 15 parts of water-based styrene-acrylic latex (BASF, Joncryl 7690), 2 parts of defoamer (BYK Chemical, BYK011), 2 parts of wetting agent (BYK Chemical, BYK326), and 11 parts of silica (Evonik, AEROSIL 150) were mixed, and then deionized water was added as a medium to dilute to a solid content of 20%. The mixture was stirred and mixed evenly to obtain the thermal imaging layer coating solution.

[0110] The preparation of the above-mentioned colorless dye dispersion involves: 20 parts of polyvinyl alcohol (Kuraray PVA203) cooking liquor (20 parts PVA203 and 80 parts deionized water were mixed and dispersed, then cooked at 90℃ for 2 hours); 50 parts of colorless dye [black thermosensitive dye ODB-2 (2-phenylamino-3-methyl-6-dibutylfluorane, Wuhan Haishan Technology); 20 parts of red thermosensitive dye Red Pigment-16 (3,3-bis(N-octyl-2-methylindole)phthalic acid lactone, Hubei Shineng Chemical Technology Co., Ltd.); and 7-... [10 parts of [4-(diethylamino)-2-ethoxyphenyl]-7-(2-methyl-1-octyl-1H-indol-3-yl)furano[3,4-b]pyridin-5(7H)-one, Henan Jiayida New Material Technology Co., Ltd.] and water were mixed and stirred for 30 minutes. The mixture was then put into a ball mill and ground until the average particle size was less than or equal to 0.50 μm. The mixture was then removed and transferred to a heat-insulating tank. The temperature was raised to 90°C and maintained at 90°C for 1 hour for thermal determination. After natural cooling, deionized water was added to dilute the mixture to a mass concentration of 25% to obtain a colorless dye dispersion.

[0111] Preparation of the above-mentioned color developer dispersion: 20 parts of polyvinyl alcohol (Kuraray PVA-203) cooking liquor (20 parts PVA203 and 80 parts deionized water were mixed and dispersed and then cooked at 90℃ for 2h), 79.9 parts of 2,4-diphenyl sulfone phenol (DBSP, Wuhan Haishan Technology Co., Ltd.) color developer, 0.1 parts of defoamer (BYK011, BYK Chemicals) and water were mixed and stirred for 30 min. The mixture was then put into a ball mill and ground until the average particle size was less than or equal to 0.2 μm. The mixture was then removed and transferred to a heat preservation tank, heated to 80℃, and kept at 80℃ for thermal setting for 4h. After natural cooling, deionized water was added to dilute the mixture to a mass concentration of 40% to obtain the color developer dispersion.

[0112] 2. Preparation of protective coating solution: The protective coating solution is prepared by mixing 60 parts of polyvinyl alcohol (Kuraray PVA-220, Japan, with a degree of alcoholysis of 88 mol%), 10 parts of silica (Evonik AEROSIL 150), 10 parts of polyethylene wax emulsion (BYK513), 10 parts of stearamide emulsion (Shandong Huling New Materials XA-25), 5 parts of wetting and leveling agent (BASF Hydropalat WE 3229), and 5 parts of ultraviolet absorber (BASF Tinuvin 1130) with deionized water as a medium to dilute to a solid content of 10%.

[0113] 3. Preparation of thermal recording materials: A back coating liquid is coated on one side of a PET film and dried at 100°C for 10 minutes to obtain a back coating. Then, a thermal imaging layer liquid is coated on the other side of the substrate and dried at 60°C for 10 minutes to obtain a thermal imaging layer. Finally, a protective layer liquid is coated and dried at 60°C for 10 minutes to obtain a protective layer, thus obtaining a thermal recording material.

[0114] Application Example 2-9 Application Examples 2-9 provide methods for preparing thermal recording materials. The difference from Application Example 1 is that the back coating of Example 1 is replaced with the coating of Example 2-9.

[0115] Compare and contrast examples 1-4 Comparative Application Examples 1-4 provide methods for preparing thermal recording materials. The difference between Comparative Application Example 1 and Application Example 2 is that the back coating of Example 1 is replaced with the coating of Comparative Examples 1-4.

[0116] Product effectiveness test 1. Testing Method (1) Optical properties of the back coating (haze and transmittance): Refer to GB / T 2410-2008 "Determination of transmittance and haze of transparent plastics". Low haze and high transmittance indicate good optical transparency and clear appearance; high haze and low transmittance indicate poor optical transparency.

[0117] (2) Surface resistance of the back coating: Refer to GB / T 33398-2016 "Method for Determination of Surface Resistance of Optical Functional Thin Films Polyethylene Terephthalate (PET) Films". The lower the resistance, the better the antistatic ability, and vice versa. Among them, a resistance of 10... 6 -10 12 Ω is an effective antistatic material with a resistance greater than 10. 12 Ω indicates a material that is neither antistatic nor insulating.

[0118] (3) Durability of surface resistance of the back coating: The thermal recording material was placed in environments with different temperatures and humidity levels, and the change in the resistance of the back coating was recorded every week for one month. The high temperature and high humidity environment was 30°C and 90% humidity; the low temperature and low humidity environment was 10°C and 15% humidity.

[0119] (4) Adhesion of the back coating: Refer to GB / T 9286-2021 "Cross-cut test of paints and varnishes", which is divided into 5 levels (levels are divided into 1-5, with 5 being the highest level). The higher the level, the better the adhesion.

[0120] (5) Water resistance of the back coating: Hold a medical cotton swab soaked in clean water and rub it back and forth on the surface of the thermal recording material, and record the number of times until the surface of the protective layer is damaged. One back and forth rubbing is recorded as "1 time".

[0121] (6) Continuous printing performance of thermal recording materials: Under different environments, the thermal recording materials prepared in Application Examples 1-7 and Comparative Application Examples 1-6 were continuously printed 1000 times using the HQ-760DY medical thermal imaging printer of Huqiu Imaging Company. The film-carrying situation (film-carrying rate = number of films carried / total number of prints × 100%) and the scratching situation of the back coating (observed after contact with the film feed roller) were recorded to evaluate the non-sticking and abrasion resistance of the back coating of the thermal recording materials.

[0122] 2. Test Results Table 1 Performance test results of each back coating and the resulting thermal recording materials

[0123] As shown in the table above, the back coatings obtained in Examples 1-9 of this invention have a haze of 9-11% and a light transmittance of 79-80%. The low haze and high light transmittance indicate good optical transparency of the back coating. The adhesion grade reaches 3-5, and the water rubbing resistance exceeds 80 cycles. Moreover, the resistivity can reach 10 ohms in both high temperature and high humidity (30℃ / 90%RH) and low temperature and low humidity (10℃ / 15%RH) environments. 7 -10 8 The resistance remains unchanged after one month of storage, indicating that the back coating of the present invention not only has antistatic properties but is also stable and durable, meeting the requirements for use in complex and variable environments. Examples 1-7 exhibit water rubbing resistance exceeding 100 cycles. Furthermore, the thermal recording materials containing the back coatings of Examples 1-7 show a low smear rate of 0-0.1% in both high-temperature and high-humidity (30℃ / 90%RH) and low-temperature and low-humidity (10℃ / 15%RH) environments, with no or only minor scratches on the back coating. This indicates that the prepared thermal recording materials can operate smoothly for extended periods with virtually no smearing.

[0124] Comparing Examples 1 and 5, it can be seen that the tape-carrying rate of the thermal recording material further prepared in Example 5 is 0.01-0.1% higher than that in Example 1. This is because the first adhesive used in Example 5 is a water-based polyurethane emulsion resin, which is slightly more tacky than the water-based fluorocarbon emulsion resin used in Example 1 (which has low surface energy properties that make the coating surface more hydrophobic and its anti-sticking effect is better than other water-based resins). In particular, the polyurethane resin becomes more tacky after absorbing water under high temperature and high humidity conditions, thus leading to an increase in the tape-carrying rate.

[0125] A comparison of Examples 1 and 6 shows that the tape-carrying rate of the thermal recording material further prepared in Example 6 is 0.001-0.01% higher than that in Example 1. The tape-carrying rate is 0.01% higher under high temperature and high humidity conditions. This is because the coating lubricity is reduced under high temperature conditions (Example 6 does not have modified paraffin wax, while modified paraffin wax provides continuous lubrication in environments above room temperature).

[0126] A comparison of Examples 1 and 7 shows that the tape yield of the thermal recording material further prepared in Example 7 is 0.002-0.008% higher than that in Example 1. The tape yield is 0.008% higher in low temperature and low humidity environments. This is because the coating lubricity is reduced at low temperatures (Example 7 does not contain polyether-modified silicone oil, while polyether-modified silicone oil provides instantaneous lubricity, especially in low temperature environments).

[0127] As can be seen from Examples 1, 6, and 7, the present invention uses a combination of organosilicon surfactant-type lubricant (polyether-modified silicone oil) and wax-based lubricant (modified paraffin emulsion). Through dynamic lubrication complementarity (the low surface tension of polyether-modified silicone oil (approximately 21 mN / m) combined with the medium-low melting point (30-50℃) of modified paraffin can form a gradient lubricating film over a wide temperature range (-30℃ to 50℃), the organosilicon surfactant-type lubricant provides instantaneous lubrication, while the wax-based lubricant continuously releases lubrication at room temperature, which helps to further improve the anti-sticking and wear resistance of the coating.

[0128] A comparison of Examples 1 and 8 shows that the thermal recording material further prepared in Example 8 exhibits a 0.04% increase in film roll rate under high temperature and high humidity conditions compared to Example 1; however, the back coating shows signs of scratching, and its adhesion grade is two levels lower than that of Example 1, with a decrease in water resistance. This is because Example 8 did not add an aziridine-modified isocyanate crosslinking agent (the first crosslinking agent), and the water-based resins and other compounds in the coating were not fully crosslinked. Consequently, the coating's abrasion resistance and water resistance are reduced, leading to water absorption and stickiness, especially under high temperature and high humidity conditions, thus resulting in an increased film roll rate.

[0129] A comparison of Examples 1 and 9 shows that the thermal recording material further prepared in Example 9 exhibits a 0.02% increase in film stripping rate under high temperature and high humidity conditions compared to Example 1; the back coating shows slight scratches, and the adhesion grade is one level lower than that of Example 1, with a decrease in water resistance. This is because Example 9 did not add an organozirconium crosslinking agent (second crosslinking agent), resulting in incomplete crosslinking of the second adhesive, polyvinyl alcohol, in the coating, leading to a reduction in water resistance and the appearance of water-absorbing film stripping under high temperature and high humidity conditions. Furthermore, the organozirconium crosslinking agent in Example 1 can delay the side reaction between the first crosslinking agent, aziridine-modified isocyanate crosslinking agent, and water. During the high-temperature (greater than 50°C) drying and curing process of the coating, the organozirconium crosslinking agent can also catalyze the rapid crosslinking and curing of the first crosslinking agent, aziridine-modified isocyanate crosslinking agent. Therefore, the absence of the organozirconium crosslinking agent in Example 9 leads to a partial loss of the first crosslinking agent, aziridine-modified isocyanate crosslinking agent, further reducing wear resistance and water resistance.

[0130] As can be seen from Examples 1, 8, and 9, the present invention improves the wear resistance and water resistance of the coating by utilizing both the first crosslinking agent and the second crosslinking agent to promote the crosslinking of the coating.

[0131] In addition, the table above also shows that: 1. Comparing Example 1 and Comparative Example 1, it can be seen that the resistance of Comparative Example 1 is basically 10. 12 Ω, with virtually no antistatic properties, and a resistance approximately 10 Ω higher than that of Example 1. 12 The Ω and the sheet ratio also increased by about 5-8%. This indicates that the PUA dispersion used in the back coating of Comparative Example 1 has virtually no antistatic properties, while Example 1 of the present invention significantly improved the antistatic properties of the coating by adding PUA-PEDOT dispersion.

[0132] 2. Comparing Example 1 and Comparative Example 2, it can be seen that the resistance of Comparative Example 2 is basically 10. 10 -10 11 Ω, approximately 10 higher resistance than in Example 1. 10 -10 11 Ω, and the tape ratio also increased by about 2-3%. This indicates that the MF capsules in Comparative Example 2, which have no antistatic properties, are difficult to impart antistatic properties to the coating (they form a micro-rough surface on the coating surface, which has no antistatic properties, thus affecting the formation of a network of conductive channels in the coating).

[0133] 3. A comparison between Example 1 and Comparative Example 3 shows that, although Comparative Example 3 still exhibits certain antistatic properties (resistance of 10 Ω) under high temperature and high humidity conditions, 10 However, it has virtually no antistatic properties under low temperature and low humidity conditions (resistance is 10Ω). 12 -10 13The resistivity of the coating increased by 3-8%, mainly because Comparative Example 3 used a conductive nanocomposite material, PEDOT / PSS dispersion, as an antistatic agent. In high-temperature and high-humidity environments, the hydrophilic groups (mainly the sulfonic acid groups (-SO3H) of PSS, which have strong hydrophilicity) can absorb ambient moisture, forming a conductive water film on the material surface and reducing surface resistivity. However, in low-humidity environments, there is little moisture, so a conductive water film cannot form on the material surface, resulting in a significant increase in surface resistivity and virtually no antistatic properties. Therefore, the conductivity of PEDOT / PSS dispersion as an antistatic agent remains highly dependent on ambient humidity, limiting its application scenarios. In addition, the back coating of Comparative Example 3 showed slight scratches, its adhesion level was one grade lower than that of Example 1, and its water resistance was also worse than that of Example 1.

[0134] 4. Comparing Example 1 and Comparative Example 4, it can be seen that the resistance of Comparative Example 4 is 10. 11 Ω is about 10 higher than in Example 1. 11 The Ω and the sheet-like ratio also increased by 1-4%. This indicates that PMMA (polymethyl methacrylate) microspheres, which lack antistatic properties, reduce the antistatic properties of the coating (they form a micro-rough surface on the coating surface and are insulators, thus lacking antistatic properties, which affects the formation of a network of conductive channels in the coating). In addition, the back coating of Comparative Example 4 showed slight scratches, and the adhesion grade was one grade lower than that of Example 1.

[0135] In summary, the thermal recording material further prepared from the coating of this invention possesses durable antistatic, anti-stick, and abrasion-resistant properties, allowing for normal use in various extreme environments. The PUA-PEDOT dispersion, acting as an antistatic agent, is produced by in-situ polymerization of EDOT monomers on the PUA surface, combining the flexibility and abrasion resistance of PUA with the conductivity of PEDOT. Its core-shell structure ensures that the material does not affect the film's light transmittance. Furthermore, it is unaffected by environmental humidity, ensuring the antistatic effect is maintained long-term in various environments and avoiding the problem of antistatic agent migration. Additionally, the MF-PEDOT microspheres, acting as a surface treatment agent, are produced by in-situ polymerization of EDOT monomers on the surface of MF microcapsules, effectively reducing adhesion during film stacking and storage. This also solves the problem of conventional surface treatment agents being insulators, providing antistatic functionality and further enhancing the antistatic and anti-stick properties of the back coating. Furthermore, this invention utilizes a combination of isocyanate crosslinking agents and organometallic crosslinking agents to jointly promote coating crosslinking. The use of adhesion promoters further enhances the coating's crosslinking and adhesion properties, while also improving its abrasion resistance. In addition, the present invention improves the anti-sticking and wear-resistant properties of the coating by using a combination of organosilicon surfactant-type lubricant and wax-type lubricant.

Claims

1. A coating, characterized in that, The raw material components are included in parts by weight as follows: 20-40 parts of waterborne polyurea-poly3,4-ethylenedioxythiophene conductive nanocomposite material 1-10 parts of waterborne melamine-formaldehyde resin-poly(3,4-ethylenedioxythiophene) conductive composite microspheres. The aqueous polyurea-poly3,4-ethylenedioxythiophene conductive nanocomposite material has a core-shell structure, wherein the core is polyurea and the shell is poly3,4-ethylenedioxythiophene; and / or; the aqueous melamine-formaldehyde resin-poly3,4-ethylenedioxythiophene conductive composite microspheres have a core-shell structure, wherein the core is melamine-formaldehyde resin and the shell is poly3,4-ethylenedioxythiophene; The raw material components of the coating also include adhesives and crosslinking agents; The crosslinking agent includes a first crosslinking agent and a second crosslinking agent, wherein the first crosslinking agent is at least one of isocyanate crosslinking agents, aziridine crosslinking agents, and organosilicon crosslinking agents, and the second crosslinking agent is at least one of aldehyde crosslinking agents, organometallic crosslinking agents, and organic acid crosslinking agents; The adhesive includes a first adhesive and a second adhesive, wherein the first adhesive is at least one of waterborne polyurethane emulsion resin, waterborne acrylic emulsion resin, and waterborne fluorocarbon emulsion resin, and the second adhesive is at least one of carboxyl-modified polyvinyl alcohol, acetyl-modified polyvinyl alcohol, and acetoacetyl-modified polyvinyl alcohol. The coating comprises, by weight, 15-30 parts of a first adhesive, 5-20 parts of a second adhesive, 1-5 parts of a first crosslinking agent, and 1-5 parts of a second crosslinking agent.

2. The coating of claim 1, wherein, The first crosslinking agent is an isocyanate crosslinking agent, and / or the second crosslinking agent is an organometallic crosslinking agent, and / or the first adhesive is an aqueous fluorocarbon emulsion resin, and / or the second adhesive is acetyl-modified polyvinyl alcohol.

3. The coating of claim 1, wherein, Based on parts by weight, the raw material components of the coating also include at least one of lubricant I, adhesion improver, wetting and leveling agent I, and thickener.

4. The coating of claim 3, wherein, The lubricant I is an organosilicon surfactant-type lubricant and / or a wax-based lubricant.

5. The coating of claim 3, wherein, The adhesion improver is an aqueous silane oligomer.

6. Process for the preparation of the coating according to any one of claims 1 to 5, characterized in that, Includes the following steps: The coating is prepared by mixing the various raw material components.

7. The production method according to claim 6, wherein The aqueous polyurea-poly3,4-ethylenedioxythiophene conductive nanocomposite material was prepared by a method including the following steps: Under the action of a first oxidant, a first catalyst, and a first dopant, the polyurea dispersion and the 3,4-ethylenedioxythiophene monomer are subjected to a first in-situ polymerization reaction to obtain the aqueous polyurea-poly3,4-ethylenedioxythiophene conductive nanocomposite material.

8. The preparation method according to claim 7, characterized in that, The aqueous melamine-formaldehyde resin-poly3,4-ethylenedioxythiophene conductive composite microspheres were prepared by a method including the following steps: Under the action of a second oxidant, a second catalyst, and a second dopant, melamine-formaldehyde resin microcapsules and 3,4-ethylenedioxythiophene monomer are subjected to a second in-situ polymerization reaction to obtain the waterborne melamine-formaldehyde resin-poly(3,4-ethylenedioxythiophene) conductive composite microspheres.

9. A coating, characterized in that, It is prepared using the coating described in any one of claims 1-5.

10. A thermal recording material, characterized in that, It includes a protective layer, a thermal imaging layer, a substrate, and a back coating layer stacked sequentially, wherein the back coating layer is made using the coating described in any one of claims 1-5.

11. The method for preparing the thermal recording material according to claim 10, characterized in that, Includes the following steps: A coating according to any one of claims 1-5 is applied to one side of a substrate to obtain a back coating layer. A thermal imaging layer coating liquid and a protective layer coating liquid are sequentially applied to the other side of the substrate to obtain a thermal imaging layer and a protective layer, respectively, thereby obtaining the thermal recording material.

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