Coating composition for forming mould pressing roller with micro-nano structure, mould pressing roller or roller drum and preparation method of mould pressing roller or roller drum

Abstract

The invention provides a coating composition for forming a mould pressing roller with a micro-nano structure, the mould pressing roller or a roller drum and a preparation method of the mould pressing roller or the roller drum. The coating composition comprises the following components in parts by weight: 7-30 parts of an acidic oligomer, 3-20 parts of an acidic monomer, 50-85 parts of a diluting monomer and 1-6 parts of a photoinitiator, wherein the acidic oligomer and the acidic monomer respectively and independently contain acidic functional groups; the acid value of the acidic oligomer is not less than 100mgKOH / g; the acid value of the acidic monomer is not less than 100mgKOH / g; the viscosity of the coating composition at 25 DEG C is less than or equal to 800 Cps. By adopting the coating composition disclosed by the invention, the problems that in the prior art, the preparation process of a mold pressing roller is tedious, the preparation of a plate roller fails due to the fact that plate pasting is easy, and excellent adhesive force, copying and filling completeness, excellent copying transfer rate, solvent cleaning meeting and the like of various roller or barrel materials are difficult to consider at the same time are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of banknotes and high-end ID cards. More specifically, this patent relates to a coating composition, a molding roller or a roller, and a preparation method thereof for forming a micro-nanostructure molding roller. The micro-nanostructure molding roller or roller can be used for subsequent UV molding stable production. Background Art

[0002] Optical anti-counterfeiting micro-nano structures processed by ultraviolet curing molding (UV molding) are usually used in anti-counterfeiting fields such as banknotes, high-end ID cards (such as the UnionPay logo of UnionPay cards). The core of UV molding production is the production of seamless molding rollers. For example, the manufacturing method of seamless molding rollers disclosed in the background technology of the Chinese patent application with the patent application publication number CN113978107A mainly adopts the electroforming process, which is as follows: first electroform a metal nickel plate, and the micro-nano structure can be completely and accurately replicated on the metal nickel plate through electroforming, and then the nickel plate is butt-jointed and bonded to the plate roller. However, the above process relies on the highly polluting and energy-consuming electroforming process. The electroforming platemaking process involves heavy metal and acid-base emissions, which pollutes the environment and is an energy-consuming and polluting process route that has been cleared by the state; at the same time, the traditional electroforming platemaking process is complicated and cumbersome, and it is difficult to achieve a high yield. The specification of a Chinese patent application with publication number CN113978107A discloses a method for forming a seamless molded roller by coating a metal surface with a polyurethane primer and then curing it with an ultraviolet light-curable coating (UV coating). However, this method is still relatively cumbersome, requiring the processing of a primer on the metal roller surface. It also fails to provide any useful information about the core UV coating used to replicate the micro-nanostructures, nor does it consider the significant impact of this coating's properties on subsequent production.

[0003] Prior art UV coating replication and curing methods for fabricating micro-nanostructures must address adhesion issues with rollers or sleeves. In practical applications, both rollers and sleeves are used. Fabricating micro-nanostructures on sleeves is more suitable for frequent replacement of embossing rollers during production, compared to direct coating on rollers. This is because sleeves are easily removable, eliminating the time and labor costs associated with direct roller replacement. Due to the diverse surface materials of rollers and sleeves, UV coatings must be widely adaptable to meet the manufacturing needs of embossing rollers of various materials. Furthermore, the use of primers must be avoided. Primers are typically solvent-based or water-based, requiring additional drying steps that complicate the manufacturing process and requiring high uniformity. These two factors can significantly reduce manufacturing efficiency and yield. These adhesion issues also hinder the successful application of the prepared embossing rollers in subsequent UV embossing processes. Insufficient adhesion can lead to damage and cracking between the coating and the roller or sleeve substrate during subsequent UV embossing, rendering the embossing roller unusable. The micro-nanostructures must exhibit a high replication transfer rate after replication to meet the requirements of subsequent UV embossing. Considering the loss of transfer efficiency in the molded product due to long-distance UV embossing, the transfer efficiency of the coating composition used to form the micro-nanostructured embossing roller should be no less than 95%. The transfer efficiency is determined by measuring the depth of the master micro-nanostructure and the depth of the coating micro-nanostructure after UV curing: transfer efficiency = depth of coating micro-nanostructure / depth of master micro-nanostructure. This requires the coating composition to balance both cure shrinkage and solvent resistance after curing. The greater the cure shrinkage, the worse the solvent resistance and the lower the transfer efficiency. Furthermore, the UV material requires excellent solvent resistance. After the micro-nanostructure is peeled off, the fluidity of the UV coating may leave excess uncured UV coating outside the replication joint of the wrap-around roller or sleeve, requiring solvent removal. Acetone, ethanol, or isopropyl alcohol are commonly used solvents for cleaning and removing uncured UV coating. Therefore, the cured UV coating (with micro-nanostructures) must be resistant to these solvents, while the uncured UV coating must be removable by these solvents. If the UV coating has poor solvent resistance after curing, it will lead to loss of micro-nanostructure morphology, making the micro-nanostructure replication transfer rate unable to reach above 95%, and even dissolution or swelling, causing the micro-nanostructure to disappear. In addition, the micro-nanostructure coating needs to have a low viscosity (≤800 Cps). Too high a viscosity will lead to insufficient filling of the micro-nanostructure, resulting in micro-nanostructure defects, or even excessive structural loss, resulting in mold release failure and plate sticking.

[0004] To this end, it is still necessary to provide a coating composition for forming a micro-nanostructure molding roller, and the coating can simplify the manufacturing process, and the formed micro-nanostructure coating has good comprehensive performance and can meet the production application of UV molding. Summary of the Invention

[0005] The main purpose of the present invention is to provide a coating composition for forming a micro-nanostructure molding roller, a molding roller or roller and a preparation method thereof, so as to solve the problems in the prior art of the molding roller, such as the complicated preparation process, easy plate sticking resulting in failure in the preparation of the plate roller, and difficulty in simultaneously taking into account excellent adhesion, replication filling integrity, excellent replication transfer rate and solvent resistance.

[0006] To achieve the above-mentioned object, according to one aspect of the present invention, a coating composition for forming a micro-nanostructured molding roller is provided, which comprises, in parts by weight: 7 to 30 parts of an acidic oligomer, 3 to 20 parts of an acidic monomer, 50 to 85 parts of a diluent monomer, and 1 to 6 parts of a photoinitiator; wherein the acidic oligomer and the acidic monomer each independently contain an acidic functional group; the acid value of the acidic oligomer is not less than 100 mgKOH / g; the acid value of the acidic monomer is not less than 100 mgKOH / g; and the viscosity of the coating composition at 25°C is ≤800 Cps.

[0007] Furthermore, the above-mentioned acidic oligomer is an acrylate oligomer, preferably an acidic oligomer with a functionality ≤ 2. Further, the model of the acidic oligomer is preferably selected from any one or more combinations of 648-1, 649, 6173 of Changxing, SB520M35 of Sartomer, EB770 of Allnex, 411, 412 of Carbon Bridge Materials, 6632 of Meiyuan, 7151 of RAHN, 5424, 4703, 4173 of IGM, and 270, 272, 275, 278, and 279 of Double Bond Chemical.

[0008] Furthermore, the acidic monomer is selected from any one or more combinations of acrylic acid phosphate monomers, methacrylic acid phosphate monomers, and carboxyl-containing acrylic acid ester monomers.

[0009] Furthermore, the coating composition is soluble in any one or more solvents selected from acetone, ethanol, and isopropanol, and / or the coating composition cannot be dissolved or swelled by any one or more solvents selected from acetone, ethanol, and isopropanol after being cured.

[0010] Furthermore, the viscosity of the above-mentioned diluent monomer is lower than 600 Cps. Preferably, the diluent monomer is a 2-3 functional acrylate monomer and / or a 1-2 functional acrylamide monomer with a viscosity lower than 300 Cps; preferably, the 2-3 functional acrylate monomer is selected from any one or more combinations of 1,6-hexanediol diacrylate (HDDA), ethoxylated 1,6-hexanediol diacrylate (EOHDDA), triethylene glycol diacrylate (TEGDA), tricyclodecane dimethanol diacrylate (DOGDA), neopentyl glycol diacrylate (NPGDA), propoxylated neopentyl glycol diacrylate (PONPGDA), tripropylene glycol diacrylate (TPGDA), and dipropylene glycol diacrylate (DPGDA); preferably, the 1-2 functional acrylamide monomer is selected from any one or more combinations of N-acryloylmorpholine (ACMO), diethylacrylamide (DEAA), dimethylacrylamide (DMAA), hydroxyethylacrylamide (HEAA), and diacetone acrylamide (DAA).

[0011] Furthermore, the above-mentioned photoinitiator is a cleavage-type free radical photoinitiator, and the cleavage-type free radical photoinitiator is preferably selected from any one or more of benzoin photoinitiators, benzyl photoinitiators, acetophenone photoinitiators, α-hydroxyketone photoinitiators, α-aminoketone photoinitiators, benzoylformate photoinitiators, and acylphosphine oxide photoinitiators.

[0012] Furthermore, the coating composition further comprises 0.1 to 10 parts of an auxiliary agent, preferably the auxiliary agent comprises any one or more of a defoaming agent, a leveling agent, and a release agent.

[0013] According to another aspect of the present invention, a method for preparing a molding roller or a drum is provided, which comprises: placing a coating composition forming a micro-nano structure on a mother film or a molding roller or a drum, laminating the micro-nano structure mother film and the molding roller or a drum with the coating composition forming the micro-nano structure located therebetween, filling and replicating the micro-nano structure mother film with the coating composition, UV curing, and peeling off the micro-nano structure mother film to form a micro-nano structure on the molding roller or a drum, and then performing a solvent cleaning step to remove excess uncured coating to obtain a molding roller or a drum having a micro-nano structure; wherein the coating is the aforementioned coating composition.

[0014] According to another aspect of the present invention, a molding roller or a roller is provided. The molding roller or the roller is prepared by the above-mentioned preparation method.

[0015] Furthermore, the depth of the micro-nanostructure coating on the surface of the embossing roller or drum is 10 nm to 20 μm, and / or the replication transfer rate of the micro-nanostructure on the surface of the embossing roller or drum is ≥95%.

[0016] Furthermore, the material of the surface of the above-mentioned molding roller or roller is independently selected from any one or more of nickel, stainless steel, carbon steel, chromium oxide, chromium, aluminum oxide and tungsten carbide.

[0017] Applying the technical solution of the present application, since the material of the mold roller or roller surface is a simple substance, alloy, metal oxide or metal carbide, the acidic functional groups in the acidic oligomer and acidic monomer in the coating composition can interact with the material of the mold roller or roller surface, and even corrode the roller surface material such as metal oxide, metal simple substance, etc., and react to form stronger chemical bonds, thereby helping to improve the adhesion of the micro-nanostructure coating formed after UV curing to the mold roller or roller. In addition, the acidic monomer contains an acrylate group or methacrylate group that can participate in polymerization or cross-linking reaction, which can react with the acidic oligomer and diluent monomer to enable the overall coating to maintain good solvent resistance. The viscosity and degree of curing of the diluent monomer both affect the curing shrinkage (affecting the replication transfer rate), the dilution effect (affecting the viscosity of the overall coating composition formula), the curing speed and the solvent resistance. The higher the monomer functionality, the easier it is to reduce the dilution effect and increase the curing shrinkage (not conducive to adhesion), but it will increase the curing speed and solvent resistance. Compared to acrylate monomers of the same functionality, acrylamide monomers have a better cure speed. Among the above factors, viscosity is also very important. A too low diluent monomer content is detrimental to reducing the overall viscosity of the coating composition, while a too high diluent monomer content is detrimental to increasing the UV-curing reaction rate of the coating composition. Preferably, controlling the diluent monomer content within the above range helps balance viscosity and photocuring reaction rate. Excessive acidic oligomer content is detrimental to reducing the overall viscosity of the coating composition, while too low an acidic oligomer content is detrimental to improving the solvent resistance of the micro-nanostructured coating formed after UV-curing the coating composition. Preferably, controlling the acidic oligomer content within the above range helps balance the viscosity of the coating composition and the solvent resistance of the micro-nanostructured coating. Preferably, controlling the diluent monomer content within the above range helps fully utilize the synergistic effect of the diluent monomer and other components, resulting in a more suitable viscosity range for the overall coating composition. Preferably, controlling the photoinitiator content within the above range helps improve the UV-curing reaction efficiency of the micro-nanostructured coating. The preferred types and contents of the above components are more conducive to improving the synergistic cooperation between the components, so that the micro-nanostructure coating prepared by using the above coating composition has stronger adhesion, replication transfer rate, micro-nanostructure integrity and solvent resistance (as well as the property of being soluble in solvents before curing) to the surface of the molding roller or roller. As a result, the molding roller or roller used in the present application to form a micro-nanostructure can not only meet the needs of the restoration of the surface structure morphology of the molding roller during manufacturing and use; but also meet the requirements of molding adhesion during use and production, and its preparation process is simpler. DETAILED DESCRIPTION

[0018] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the embodiments.

[0019] As analyzed in the background technology of this application, there are problems in the prior art such as the complicated preparation process of the embossing roller, easy plate sticking resulting in failure in the preparation of the plate roller, and difficulty in simultaneously taking into account excellent adhesion, replication filling integrity, excellent replication transfer rate and solvent resistance. In order to solve this problem, this application provides a coating composition for forming a micro-nanostructure embossing roller, a embossing roller or a roller and a preparation method thereof.

[0020] In a typical embodiment of the present application, a coating composition for forming a micro-nanostructure molding roller is provided, which comprises, in parts by weight: 7 to 30 parts of an acidic oligomer, 3 to 20 parts of an acidic monomer, 50 to 85 parts of a diluent monomer, and 1 to 6 parts of a photoinitiator; wherein the acidic oligomer and the acidic monomer each independently contain an acidic functional group; the acid value of the acidic oligomer is not less than 100 mgKOH / g; the acid value of the acidic monomer is not less than 100 mgKOH / g; and the viscosity of the coating composition at 25°C is ≤800 Cps.

[0021] Because the surface of the embossing roller or drum is made of a single substance, alloy, metal oxide, or metal carbide, the acidic functional groups in the acidic oligomers and acidic monomers in the coating composition can interact with the surface material of the embossing roller or drum, even corroding the surface material, such as metal oxides or single metals, to form stronger chemical bonds. This reaction helps improve the adhesion of the micro-nanostructured coating formed after UV curing to the embossing roller or drum. Furthermore, the acidic monomer contains acrylate or methacrylate groups that can participate in polymerization or crosslinking reactions. These groups react with the acidic oligomers and diluent monomers, allowing the overall coating to maintain good solvent resistance. The diluent monomer affects cure shrinkage (affecting the replication transfer rate), dilution effect (affecting the overall viscosity of the coating composition formulation), cure speed, and solvent resistance. Higher monomer functionality tends to reduce dilution effect and increase cure shrinkage (impeding adhesion), but it also increases cure speed and solvent resistance. Compared to acrylate monomers of the same functionality, acrylamide monomers have a better cure speed. Among the above factors, viscosity is also very important. If the viscosity of the coating is too high (more than 800 Cps), it will lead to incomplete filling, resulting in replication loss and thus being unable to obtain a usable molded roller. If the content of the diluent monomer is too low, it will be detrimental to reducing the viscosity of the coating composition as a whole. If the content of the diluent monomer is too high, it will be detrimental to improving the adhesion of the coating composition. It is preferred that the number of diluent monomers is controlled within the above range to help take into account both its viscosity and adhesion. If the content of the acidic oligomer is too high, it will be detrimental to reducing the viscosity of the coating composition as a whole. If the number of acidic oligomers is too low, it will be detrimental to improving the solvent resistance and adhesion of the micro-nanostructure coating formed after the coating composition is ultraviolet-cured. It is preferred that the number of acidic oligomers is controlled within the above range to help take into account the adhesion, viscosity and solvent resistance of the micro-nanostructure coating of the coating composition. It is preferred that the content of the diluent monomer is controlled within the above range to help give full play to the synergistic effect of the diluent monomer and other components, so that the viscosity range of the coating composition as a whole is more suitable. It is preferred that the content of the photoinitiator is controlled within the above range to help improve the ultraviolet-curing reaction efficiency of the micro-nanostructure coating. The preferred types and contents of the above components are more conducive to improving the synergistic cooperation between the components, so that the micro-nanostructure coating prepared by using the above coating composition has stronger adhesion, replication transfer rate, micro-nanostructure integrity and solvent resistance (as well as the property of being soluble in solvents before curing) to the surface of the molding roller or roller. As a result, the molding roller or roller used in the present application to form a micro-nanostructure can not only meet the needs of the restoration of the surface structure morphology of the molding roller during manufacturing and use; but also meet the requirements of molding adhesion during use and production, and its preparation process is simpler.

[0022] In one embodiment of the present application, the above-mentioned acidic oligomer is an acrylate oligomer, preferably an acidic oligomer with a functionality ≤ 2. Further, the model of the acidic oligomer is preferably selected from Changxing's 648-1, 649, 6173, Sartomer's SB520M35, Allnex's EB770, Carbon Bridge Materials' 411, 412, Meiyuan's 6632, RAHN's 7151, IGM's 5424, 4703, 4173, and Double Bond Chemical's 270, 272, 275, 278, and 279. Any one or more combinations thereof.

[0023] Acidic oligomers usually obtain a higher acid value by introducing acidic groups such as carboxylic acid, sulfonic acid, etc. into the molecular structure. Such acidic oligomers can provide stronger adhesion to the substrate. The acidic oligomers of the present application are acrylate oligomers, which contain acrylate groups that can be polymerized or cross-linked with other components, thereby helping to maintain good solvent resistance after UV curing. It is further preferred that the functionality of the acidic oligomer is ≤2 to avoid the problem of low replication transfer rate caused by excessive cross-linking and excessive shrinkage. At the same time, the preferred above-mentioned oligomers have relatively good solvent resistance after curing and are easily dissolved by corresponding solvents before curing.

[0024] In one embodiment of the present application, the acidic monomer is selected from any one or more combinations of acrylic acid phosphate monomers, methacrylic acid phosphate monomers, and carboxyl-containing acrylic acid ester monomers.

[0025] The acidic monomers mentioned above are preferred as they help reduce the overall viscosity of the coating composition. Furthermore, carboxylic acid-containing acrylate monomers such as acrylic acid (AA) and β-acryloyloxypropionic acid (β-CEA) are preferred; phosphate-containing acrylate and methacrylate monomers such as IGM's 4703, Sartomer's SR9050 and SR9051, allnex's EB168 and EB170, Double Bond's 9167, and RAHN's 40 are preferred.

[0026] In one embodiment of the present application, the above-mentioned coating composition is soluble in any one or more solvents of acetone, ethanol, and isopropanol, and / or the coating composition cannot be dissolved or swelled by any one or more solvents of acetone, ethanol, and isopropanol after curing.

[0027] The preferred coating composition having the above-mentioned solubility can remove excess UV replication coating, thereby forming a molding roller with no UV replication coating residue in the micro-nano structure.

[0028] The dilution monomer needs to comprehensively consider viscosity (dilution ability), curing speed, curing shrinkage (affecting the replication transfer rate) and solvent resistance (solubility before curing). The higher the monomer functionality, the lower the dilution effect and the greater the curing shrinkage (not conducive to adhesion), but the higher the curing speed and solvent resistance. Compared with acrylate monomers with the same functionality, acrylamide monomers have better curing speed. Among the above factors, viscosity is still very important. Preferably, the viscosity of the dilution monomer is lower than 600 Cps. Further preferably, the dilution monomer is a combination of one or more of an acrylate monomer or an acrylamide monomer having a viscosity lower than 600 Cps. Acrylate monomers such as 1,6-hexanediol diacrylate (HDDA), ethoxylated 1,6-hexanediol diacrylate (EOHDDA), triethylene glycol diacrylate (TEGDA), tricyclodecane dimethanol diacrylate (DOGDA), neopentyl glycol diacrylate (NPGDA), propoxylated neopentyl glycol diacrylate (PONPGDA), tripropylene glycol diacrylate (TPGDA), dipropylene glycol diacrylate (DPGDA), trimethylolpropane triacrylate (TMPTA), ethoxylated trimethylolpropane triacrylate (EOTMPTA), propoxylated trimethylolpropane triacrylate (POTMPTA), pentaerythritol triacrylate (PET3A), pentaerythritol tetraacrylate (PET4A), dihydroxy Methylpropane tetraacrylate, trimethylolpropane tetraacrylate (DTMPTTA), 2-phenoxyethyl acrylate (PHEA), ethoxylated phenoxy acrylate (PH3EOA), tetrahydrofurfuryl acrylate (THFA), isobornyl acrylate (IBOA), benzyl acrylate (BA), 4-tert-butylcyclohexyl acrylate (TBCHA), hydroxyethyl acrylate (HEA), hydroxypropyl acrylate (HPA), cyclotrimethylolpropane formal acrylate (CTFA), dicyclopentenyl ethoxylated acrylate (DCPEA); acrylamide monomers such as N-acryloylmorpholine (ACMO), diethylacrylamide (DEAA), dimethylacrylamide (DMAA), hydroxyethylacrylamide (HEAA), and diacetoneacrylamide (DAA).

[0029] Furthermore, the preferred diluent monomers are 2-3 functional acrylate monomers and / or 1-2 functional acrylamide monomers with a viscosity below 300 Cps. This is because high-functionality monomers have higher cure shrinkage, which results in lower replication transfer rates. At the same time, monofunctional acrylate monomers have lower cure speeds than acrylamide monomers. Furthermore, the viscosity of the diluent monomers significantly affects the overall viscosity of the formulation. Excessively high overall formulation viscosity, such as exceeding 800 Cps, can result in incomplete replication. Therefore, in order to achieve a replication transfer rate above 95% while balancing cure speed and viscosity, monomers with a viscosity below 300 Cps, such as 2-3 functional acrylate monomers and 1-2 functional acrylamide monomers, should be selected. Furthermore, among the above-mentioned monomers, preferred are 2-functional acrylate monomers and 1-2 functional acrylamide monomers with a viscosity below 300 Cps. Preferably, the acrylate monomer with a functionality of 2-3 is selected from any one or more combinations of 1,6-hexanediol diacrylate (HDDA), ethoxylated 1,6-hexanediol diacrylate (EOHDDA), triethylene glycol diacrylate (TEGDA), tricyclodecane dimethanol diacrylate (DOGDA), neopentyl glycol diacrylate (NPGDA), propoxylated neopentyl glycol diacrylate (PONPGDA), tripropylene glycol diacrylate (TPGDA), and dipropylene glycol diacrylate (DPGDA); and preferably, the acrylamide monomer with a functionality of 1-2 is selected from any one or more combinations of N-acryloylmorpholine (ACMO), diethylacrylamide (DEAA), dimethylacrylamide (DMAA), hydroxyethylacrylamide (HEAA), and diacetone acrylamide (DAA).

[0030] In order to further improve the efficiency of the UV curing reaction, in one embodiment of the present application, the above-mentioned photoinitiator is preferably a cleavage-type free radical photoinitiator, and the cleavage-type free radical photoinitiator is preferably selected from any one or more of benzoin photoinitiators, benzyl photoinitiators, acetophenone photoinitiators, α-hydroxyketone photoinitiators, α-aminoketone photoinitiators, benzoylformate photoinitiators, and acylphosphine oxide photoinitiators.

[0031] To further improve the production yield of the micro-nanostructured coating, in one embodiment of the present application, the coating composition preferably further comprises 0.1 to 10 parts of an additive, wherein the additive comprises one or more of a defoamer, a leveling agent, and a release agent. The defoamer, leveling agent, and release agent can be commonly used in the market and are not described in detail here.

[0032] In another typical embodiment of the present application, a method for preparing a molding roller or a drum is provided, which comprises: placing a coating composition forming a micro-nano structure on a mother film or a molding roller or a drum, laminating the micro-nano structure mother film and the molding roller or a drum with the coating composition forming the micro-nano structure located therebetween, filling and replicating the micro-nano structure mother film with the coating composition, UV curing, and peeling off the micro-nano structure mother film to form a micro-nano structure on the molding roller or a drum, and then performing a solvent cleaning step to remove excess uncured coating to obtain a molding roller or a drum having a micro-nano structure; wherein the coating is the aforementioned coating composition.

[0033] The micro-nanostructured coating prepared by the above preparation method has stronger adhesion and replication transfer rate to the surface of the molding roller or roller, and its preparation process is simple and low-cost, which is more in line with market demand.

[0034] In another typical embodiment of the present application, a molding roller or a roller is provided, and the molding roller or the roller is prepared by the above-mentioned preparation method.

[0035] Since the surface of the above-mentioned embossing roller or roller is covered with the micro-nanostructure coating prepared by the coating composition and preparation method of the present application, the micro-nanostructure coating has strong adhesion to the surface of the embossing roller or roller and has a high replication transfer rate.

[0036] In one embodiment of the present application, the depth of the micro-nanostructure coating on the surface of the embossing roller or drum is 10 nm to 20 μm, and / or the replication transfer rate of the micro-nanostructure on the surface of the embossing roller or drum is ≥95%.

[0037] The coating composition of the present application can be used to prepare a micro-nanostructure coating within the above-mentioned depth range, and the replication transfer rate of the micro-nanostructure is within the above-mentioned range, thereby better helping to meet market demand.

[0038] In one embodiment of the present application, the material of the surface of the above-mentioned molding roller or roller is independently selected from any one or more of nickel, stainless steel, carbon steel, chromium oxide, chromium, aluminum oxide and tungsten carbide.

[0039] The coating of the present application can form a micro-nano structure on the surface of the molding roller or roller made of the above-mentioned materials. Therefore, the coating of the present application has a wide range of adhesion adaptability.

[0040] The beneficial effects of the present application will be further illustrated below with reference to examples.

[0041] Examples 1 to 4

[0042] The specific components and raw materials of the coating compositions of Examples 1 to 4 and their weight percentages are shown in Table 1. The coating composition is placed between the surface of rollers of different materials (surface materials are nickel, chromium oxide, and tungsten carbide, respectively) or rollers (surface material is aluminum oxide) and the master film. By filling and replicating the micro-nanostructure of the master film, UV curing, and peeling the master film, the coating composition accurately replicates the micro-nanostructure of the master film and forms a micro-nanostructure coating on the surface of the roller or roller, thereby forming a molded roller. The micro-nanostructure depths of the replicated master films in Examples 1 and 2 are 6μm blazed gratings and 10nm zero-order gratings, respectively. The micro-nanostructure of the replicated master films in Examples 3 and 4 includes cylindrical lenses with a depth of 20μm, respectively.

[0043] Comparative Examples 1 to 4

[0044] The specific components and raw materials of the coating compositions of Comparative Examples 1 to 4 and their weight percentages are shown in Table 1. The coating composition is placed between the surface of rollers of different materials (surface materials are nickel, chromium oxide, and tungsten carbide, respectively) or rollers (aluminum oxide) and the mother film. By filling and replicating the micro-nanostructure of the mother film, UV curing, and peeling the mother film, the coating composition accurately replicates the micro-nanostructure of the mother film and forms a micro-nanostructure coating on the surface of the roller or roller, thereby forming a molded roller. The micro-nanostructure of the replicated mother film in Comparative Examples 1 and 2 respectively includes a blazed grating with a depth of 6μm and a zero-order grating with a thickness of 10nm. The micro-nanostructure of the replicated mother film in Comparative Examples 3 and 4 respectively includes a cylindrical lens with a depth of 20μm.

[0045] The abbreviations of raw materials in Table 1 have the following meanings:

[0046] 272: Carboxylic acid polyester acrylate oligomer (acid value 200mgKOH / g), double bond chemical product;

[0047] 278: Chlorinated polyester acrylate oligomer (acid value 100mgKOH / g), double bond chemical product;

[0048] 6340: Polyester acrylate oligomer (acid value 10 mgKOH / g), product of Changxing Chemical Co.; DPHA: dipentaerythritol hexaacrylate, viscosity 5000-7000 cps at 25°C, hexafunctional;

[0049] PETTEOA: ethoxylated pentaerythritol tetraacrylate, viscosity 200 cps at 25°C, tetrafunctionality; DOGDA: tricyclodecane dimethanol diacrylate, viscosity 110-150 cps at 25°C, difunctionality; ACMO: N-acryloylmorpholine, viscosity 10-15 cps at 25°C, monofunctionality;

[0050] TPO: 2,4,6-trimethylbenzoyldiphenylphosphine oxide;

[0051] 819: Bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide;

[0052] SR9051: acidic monomer (acid value 152 mgKOH / g), product of Sartomer;

[0053] Airex900: defoaming agent, Tego series product of Evonik;

[0054] Glide410: leveling agent, Tego series product of Evonik;

[0055] S360: Release agent, a product of Carbon Bridge Company.

[0056] Table 1

[0057]

[0058]

[0059] Performance testing:

[0060] Adhesion fastness refers to the ASTM D 3359 adhesion fastness determination standard, and the ratings are from 0B to 5B. Adhesion fastness is improved in sequence, 5B is the best, no falling off occurs, and 0B is the worst, all falling off occurs.

[0061] The chemical resistance test is to soak in the specified solvent (isopropyl alcohol, ethanol and acetone) for 30 minutes to see if the coating is damaged.

[0062] Replication integrity was judged by macroscopic observation.

[0063] Replication transfer rate = depth of coating micro-nanostructure / depth of master micro-nanostructure.

[0064] The micro-nanostructure coatings in the examples and comparative examples were tested for adhesion fastness, chemical resistance, replication integrity, and replication transfer rate. The test results are shown in Table 2.

[0065] Table 2

[0066]

[0067]

[0068] Examples 1-4 all achieved excellent micro-nanostructure replication integrity, solvent resistance, and adhesion to different rollers or drums, thereby producing quality embossing rollers. Furthermore, due to the excellent solvent resistance, completely consistent replication transfer rates were achieved after removing excess UV coating using acetone, ethanol, or isopropanol solvents, with the micro-nanostructure replication transfer rates all being no less than 95%. However, in Comparative Examples 1 and 2, due to the lack of acidic monomers or oligomer components, the adhesion was significantly deteriorated, leading to incomplete replication of some roller substrates. Their adhesion also failed to meet the quality requirements for embossing roller adhesion, and interlayer damage between the roller micro-nanostructure coating and the substrate occurred during UV embossing. In Comparative Example 3, the diluent monomer used a high-functional monomer, DPHA, with a viscosity exceeding 600 Cps. Due to the excessively high viscosity of the resulting coating (greater than 800 Cps), a large number of incomplete filling issues occurred, resulting in defects in the replicated micro-nanostructures. Furthermore, due to the significant shrinkage of DPHA, the quality requirements for roller adhesion were also not met. Comparative Example 4 partially employed a non-high-acid-value acrylate oligomer and a tetrafunctional acrylate, PETTEOA. Even with the partial use of the non-high-acid-value oligomer, adhesion was significantly reduced, and replication incompleteness occurred on all substrates except the alumina substrate. Furthermore, the tetrafunctional acrylate, PETTEOA, exhibited relatively high cure shrinkage, significantly reducing the replication transfer rate. The oligomer also exhibited poor solvent resistance. When removing excess UV coating using acetone, ethanol, or isopropanol, only isopropanol did not dissolve the coating, resulting in a replication transfer rate of 89% for the cylindrical lens structure on the alumina substrate. This resulted in severe loss of the cylindrical lens structure, failing to meet the requirements for subsequent processing and application of the embossing plate roller.

[0069] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0070] Because the surface of the embossing roller or drum is made of a single substance, alloy, metal oxide, or metal carbide, the acidic functional groups in the acidic oligomers and acidic monomers in the coating composition can interact with the surface material of the embossing roller or drum, even corroding the surface material, such as metal oxides or single metals, forming stronger chemical bonds. This reaction helps improve the adhesion of the micro-nanostructured coating formed after UV curing to the embossing roller or drum. Furthermore, the acidic monomer contains acrylate or methacrylate groups that can participate in polymerization or crosslinking reactions. These groups react with the acidic oligomers and diluent monomers, enabling the overall coating to maintain good solvent resistance. The viscosity and degree of cure of the diluent monomer both affect cure shrinkage (affecting the replication transfer rate), dilution effect (affecting the overall viscosity of the coating composition), cure speed, and solvent resistance. Higher monomer functionality tends to reduce dilution effect and increase cure shrinkage (impeding adhesion), but it also increases cure speed and solvent resistance. Compared to acrylate monomers of the same functionality, acrylamide monomers have a better cure speed. Among the above factors, viscosity is also very important. Too low a content of diluent monomer is not conducive to reducing the viscosity of the coating composition as a whole, while too high a content of diluent monomer is not conducive to increasing the UV curing reaction speed of the coating composition as a whole. Preferably, controlling the number of diluent monomers within the above range helps to balance its viscosity and photocuring reaction speed. Too high a content of acidic oligomers is not conducive to reducing the viscosity of the coating composition as a whole, while too low a content of acidic oligomers is not conducive to improving the solvent resistance and adhesion of the micro-nanostructure coating formed after UV curing of the coating composition. Preferably, controlling the number of acidic oligomers within the above range helps to balance the viscosity of the coating composition and the solvent resistance and adhesion of the micro-nanostructure coating. Preferably, controlling the content of diluent monomers within the above range helps to give full play to the synergistic effect of the diluent monomers and other components, so that the viscosity range of the coating composition as a whole is more appropriate. Preferably, controlling the content of photoinitiator within the above range helps to improve the UV curing reaction efficiency of the micro-nanostructure coating. The preferred types and contents of the above components are more conducive to improving the synergistic cooperation between the components, so that the micro-nanostructure coating prepared by using the above coating composition has adhesion to the surface of embossing rollers or rollers of various materials, replication transfer rate, micro-nanostructure replication integrity and meets the removal of residual UV coating of the micro-nanostructure during the manufacturing process (the micro-nanostructure coating needs to have good solvent resistance after curing and can be dissolved by solvent before curing). As a result, the embossing roller or roller used in the present application to form a micro-nanostructure can not only meet the needs of restoring the surface structure morphology of the embossing roller during manufacturing and use; but also meet the requirements of molding adhesion during use and production, and its preparation process is simpler.

[0071] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A coating composition for forming a micro-nanostructured molding roller, characterized in that: In parts by weight, the coating composition comprises: 7 to 30 parts of an acidic oligomer; 3 to 20 parts of an acidic monomer; 50 to 85 parts of diluent monomer; and 1 to 6 parts of photoinitiator; wherein the acidic oligomer and the acidic monomer each independently contain an acidic functional group; The acid value of the acidic oligomer is not less than 100 mgKOH / g; The acid value of the acidic monomer is not less than 100 mgKOH / g; The viscosity of the coating composition at 25° C. is ≤800 Cps.

2. The coating composition for forming a micro-nanostructured molding roller according to claim 1, characterized in that: The acidic oligomer is an acrylate oligomer, preferably an oligomer with a functionality ≤ 2, and further preferably, the model of the acidic oligomer is selected from any one or more combinations of 648-1, 649, 6173 of Changxing, SB520M35 of Sartomer, EB770 of Allnex, 411, 412 of Carbon Bridge Materials, 6632 of Meiyuan, 7151 of RAHN, 5424, 4703, 4173 of IGM, and 270, 272, 275, 278, and 279 of Double Bond Chemical.

3. The coating composition for forming a micro-nanostructured molding roller according to claim 1 or 2, characterized in that: The acidic monomer is selected from any one or more combinations of acrylic acid phosphate monomers, methacrylic acid phosphate monomers, and carboxyl-containing acrylic acid ester monomers.

4. The coating composition for forming a micro-nanostructured molding roller according to any one of claims 1 to 3, characterized in that: The coating composition is soluble in any one or more solvents selected from acetone, ethanol, and isopropanol, and / or the coating composition cannot be dissolved or swelled by any one or more solvents selected from acetone, ethanol, and isopropanol after being cured.

5. The coating composition for forming a micro-nanostructured molding roller according to any one of claims 1 to 4, characterized in that: The viscosity of the diluent monomer is lower than 600 Cps. Preferably, the diluent monomer is a 2-3 functional acrylate monomer and / or a 1-2 functional acrylamide monomer having a viscosity lower than 300 Cps. Preferably, the 2-3 functional acrylate monomer is selected from any one or more combinations of 1,6-hexanediol diacrylate (HDDA), ethoxylated 1,6-hexanediol diacrylate (EOHDDA), triethylene glycol diacrylate (TEGDA), tricyclodecane dimethanol diacrylate (DOGDA), neopentyl glycol diacrylate (NPGDA), propoxylated neopentyl glycol diacrylate (PONPGDA), tripropylene glycol diacrylate (TPGDA), and dipropylene glycol diacrylate (DPGDA). Preferably, the 1-2 functional acrylamide monomer is selected from any one or more combinations of N-acryloylmorpholine (ACMO), diethylacrylamide (DEAA), dimethylacrylamide (DMAA), hydroxyethylacrylamide (HEAA), and diacetone acrylamide (DAA).

6. The coating composition for forming a micro-nanostructured molding roller according to any one of claims 1 to 5, characterized in that: The photoinitiator is a cleavage-type free radical photoinitiator, and preferably the cleavage-type free radical photoinitiator is selected from any one or more of benzoin photoinitiators, benzyl photoinitiators, acetophenone photoinitiators, α-hydroxyketone photoinitiators, α-aminoketone photoinitiators, benzoylformate photoinitiators, and acylphosphine oxide photoinitiators.

7. The coating composition for forming a micro-nanostructured molding roller according to any one of claims 1 to 6, characterized in that: The coating composition further comprises 0.1 to 10 parts of an auxiliary agent, and preferably the auxiliary agent comprises any one or more of a defoaming agent, a leveling agent, and a release agent.

8. A method for preparing a molded roller or a roller, characterized in that: The preparation method comprises: placing a coating composition for forming a micro-nano structure on a mother film or a molding roller or a drum, laminating the micro-nano structure mother film and the molding roller or a drum with the coating composition for forming a micro-nano structure located therebetween, filling and replicating the micro-nano structure mother film with the coating composition, UV curing, peeling off the micro-nano structure mother film, and then performing a solvent cleaning step to remove excess uncured coating to obtain a molding roller or a drum having a micro-nano structure; Wherein, the coating is the coating composition according to any one of claims 1 to 7.

9. A molding roller or drum, characterized in that The molding roller or roller is prepared by the preparation method according to claim 8.

10. The embossing roller or drum according to claim 9, characterized in that The depth of the micro-nano structure coating on the surface of the embossing roller or drum is 10 nm to 20 μm, and / or the replication transfer rate of the micro-nano structure on the surface of the embossing roller or drum is ≥95%.

11. The embossing roller or drum according to claim 9 or 10, characterized in that The material of the molding roller or the surface of the roller is independently selected from any one or more of nickel, stainless steel, carbon steel, chromium oxide, chromium, aluminum oxide and tungsten carbide.

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