Thermal printing material with cleaning function and preparation method and application thereof

Abstract

The present invention belongs to the technical field of printing materials, and provides a thermal printing material with a cleaning function, and a preparation method and application thereof. The thermal printing material provided by the present invention includes a substrate, a thermal imaging layer, and a protective layer stacked in sequence. The raw materials for preparing the protective layer include a first film-forming material, a second film-forming material, and a cleaning function material. The cleaning function material includes a rare earth oxide. The first film-forming material is at least one of modified polyvinyl alcohol, styrene acrylic resin, polyurethane resin, polyacrylic resin, styrene maleic anhydride copolymer, and water-based epoxy resin. The second film-forming material is a carbonyl compound and / or an amino compound. The thermal printing material provided by the present invention can clean the thermal print head while printing. The thermal print head remains clean for a long time and has a long service life. It does not affect the printing effect of the output information image. The thermal printing material has the characteristics of high transparency, clear image, high density, and no scratches.

Description

Technical Field

[0001] The present invention relates to the technical field of printing materials, and more particularly to a thermal printing material with a cleaning function, a preparation method thereof, and an application thereof. Background Art

[0002] Thermal printing technology offers advantages such as fast printing speed, low noise during printing, high-resolution printing, and excellent clarity. The application scope of thermal printers has expanded from traditional applications with lower information requirements, such as point-of-sale (POS), fax, and office applications, to applications with higher requirements for information expression and data transmission, such as logistics labels, photos, medical images, and engineering drawings. The key component of thermal printing technology and thermal printers is the precision-engineered thermal print head. The raised portion of the heating element of the thermal print head reaches several millimeters, and the coatings such as the resistive and conductive layers of the thermal print head reach nanometer-micrometer levels. The resolution of thermal print heads has increased from the conventional 203dpi and 320dpi to 508dpi and even 600dpi. These developments have placed higher demands on printing consumables, thermal print head cleaning, thermal print head maintenance, and equipment care. This is especially true for printing equipment used in medical imaging and medical diagnostics, which places even higher demands on thermal print heads and their cleanliness.

[0003] At present, to the cleaning of thermal print head, generally need after shutting down, wait for thermal print head to cool down completely, just can use cleaning tool (such as soft cloth, handheld cleaning card) to clean, and cooperate cleaning solvent (such as absolute ethanol, industrial alcohol, aqueous detergent containing surfactant, oily detergent containing surfactant) to carry out repeated manual wiping.But this method need use cleaning solvent, easily cause damages such as corrosion, oxidation to the coating and electronic device on thermal print head, and manual cleaning exists and is difficult to clean completely, to the problem of the precise position or local excessive cleaning of thermal print head, easily cause artificial secondary damage to thermal print head, also there is the problem that inefficiency, manual maintenance cost are high.Chinese patent (publication number CN221067543U) is by installing the devices such as fixed plate, chute, slide block, cleaning cotton additional on thermal print head, utilizes cleaning cotton to cooperate cleaning solvent to clean thermal print head after shutting down cooling, although avoid manual cleaning, the cleaning effect of this method is poor, and cleaning cotton easily falls off when using, causes secondary pollution to thermal print head. The Chinese patent (publication number CN103612489A) sets up a cleaning program by changing the printer program. The high load and multiple heating of the thermal print head melt the dirt, and the paper feeding method is used to remove the dirt. However, this method has a poor cleaning effect and requires multiple repeated operations. Even repeated operations cannot remove non-thermal sensitive dirt on the thermal print head.

[0004] Therefore, there is an urgent need to develop an efficient cleaning method for thermal print heads, which has a good cleaning effect on both thermal and non-thermal sensitive dirt, avoids secondary pollution of the thermal print head, and at the same time ensures that the printing effect is not affected, and the thermal print head can work continuously and uninterruptedly for a long time. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention proposes a thermal printing material with a cleaning function, a preparation method thereof, and an application thereof. The thermal printing material provided by the present invention can clean the thermal print head while printing, and can effectively remove adhesions on the surface of the thermal print head (the print head adhesion test results show that less than 2% of the thermal print head surfaces have adhesions), avoiding secondary contamination of the thermal print head. The cleaned thermal print head can print more than 5,000 sheets without surface scratches, indicating that the cleaning is completed without affecting the printing performance of the thermal print head. The thermal print head can work continuously and uninterruptedly for a long time, and the thermal printing material has good water resistance (water resistance test times ≥ 50 times), scratch resistance, wear resistance, good permeability, and low haze (haze 36.7-61.5%).

[0006] A first aspect of the present invention provides a thermal printing material.

[0007] Specifically, a thermal printing material includes a substrate, a thermal imaging layer and a protective layer stacked in sequence. The raw materials for preparing the protective layer include a first film-forming material, a second film-forming material and a cleaning functional material. The cleaning functional material includes a rare earth oxide. The first film-forming material is at least one of modified polyvinyl alcohol, styrene acrylic resin, polyurethane resin, polyacrylic resin, styrene maleic anhydride copolymer, and water-based epoxy resin. The second film-forming material is a carbonyl compound and / or an amino compound.

[0008] The present invention adds rare earth oxide as a cleaning functional material in the protective layer of the thermal printing material. First, the rare earth oxide has a chemical mechanical polishing effect. The protective layer is located on the surface of the thermal printing material. During the printing process of the thermal printing material, the thermal print head is pressed down and closely adheres to the thermal printing material, so that the cleaning functional material is fully in contact with the thermal print head. Under the action of the sliding of the thermal printing material and the mutual displacement of the thermal print head, the cerium oxide on the surface of the thermal printing material can simultaneously complete the precision polishing of the thermal print head. If there are accumulated impurities, dust, coating debris and other foreign matter on the surface of the thermal print head, they can be removed during the printing process, ensuring the cleanliness and overall integrity of the thermal print head. In this way, the thermal print head can be kept clean for a long time, heat evenly, and image well, and the life of the thermal print head can be extended as much as possible. This solves the problem that a large amount of debris falls off the thermal print head after long-term work, the coating softens and sticks to the head, and other substances accumulate on the surface, which in turn leads to printing scratches, black and white stripes, and shortened life. Secondly, the first film-forming material can undergo a cross-linking reaction with the second film-forming material. Since rare earth oxides inherently have redox properties, they can also act as a catalyst for the cross-linking and strengthening reaction between the first and second film-forming materials, accelerating the reaction rate and improving the strength, hardness, and density of the protective layer. This imparts excellent scratch resistance, abrasion resistance, and water resistance to the coating, preventing softening or chipping during printing and use, which could foul the thermal printhead. This allows the cleaning material to better exert its cleaning capabilities, eliminating the need for a aging process in a specific temperature and humidity environment, simplifying the production process and improving production efficiency. Furthermore, the relatively low hardness of rare earth oxides prevents mechanical scratching of the thermal printhead.

[0009] Preferably, the mass percentage of the rare earth oxide in the cleaning functional material is 50-100%.

[0010] Further preferably, the mass percentage of the rare earth oxide in the cleaning functional material is 80-100%.

[0011] Preferably, the rare earth oxide is at least one of cerium oxide, lanthanum oxide, praseodymium oxide, neodymium oxide, and yttrium oxide.

[0012] More preferably, the rare earth oxide is cerium oxide.

[0013] Preferably, the average particle size of the cerium oxide is ≤100 nm, and / or the specific surface area of ​​the cerium oxide is ≥20 m 2 / g. Specific cerium oxide helps ensure the permeability of thermal printing materials.

[0014] Preferably, the cleaning functional material includes other oxides, and the other oxides are at least one of silicon oxide, aluminum oxide, and zirconium oxide.

[0015] Preferably, the mass percentage of other oxides in the cleaning functional material is 0-20%, and / or the average particle size of the other oxides is ≤100 nm. Other oxides with a suitable average particle size are conducive to obtaining a transparent appearance of the thermal printing material.

[0016] Silicon oxide, aluminum oxide, and zirconium oxide have high hardness and provide excellent physical scraping and mechanical polishing properties. They are effective in removing large particles of accumulated adhesive from printheads. However, excessive use can damage the printhead and shorten its lifespan. Cerium oxide, with its low hardness, does not physically damage the printhead. Its chemical polishing, primarily due to its redox properties, makes it particularly suitable for cleaning delicate structures and is particularly effective in removing tiny adhesive particles from the finer details of printheads. Using cerium oxide in combination with other oxides can also reduce costs and improve the condition of the protective fluid.

[0017] Preferably, the first film-forming material is at least one of itaconic acid-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, and silane-modified polyvinyl alcohol, and / or the first film-forming material has a degree of polymerization of 1700-3500, and / or the first film-forming material has an alcoholysis degree of 88% or greater. A first film-forming material with an appropriate degree of polymerization and alcoholysis degree ensures moderate coating viscosity and excellent water resistance for the protective layer.

[0018] Preferably, the second film-forming material is at least one of polyamide polyamine epichlorohydrin resin, polyaziridine, polycarbodiimide, adipic acid dihydrazide, hydroxymethyl melamine resin, and aldehyde compounds (such as aldehyde compounds with a weight average molecular weight of less than 120).

[0019] Preferably, in terms of mass percentage, the raw materials for preparing the protective layer include 50-80% of the first film-forming material, 0.05-8% of the second film-forming material, and 1-20% of the cleaning functional material.

[0020] Further preferably, in terms of mass percentage, the raw materials for preparing the protective layer include 60-80% of the first film-forming material, 0.06-8% of the second film-forming material, and 3-15% of the cleaning functional material.

[0021] Preferably, the mass ratio of the first film-forming material to the second film-forming material is (10-100):1.

[0022] Preferably, the protective layer preparation materials also include at least one of an anti-settling agent, a catalyst, a lubricant, a nanofiller, a water-based resin, a wetting and leveling agent, a thickener, an acid-base modifier, and a defoamer. The anti-settling agent facilitates good dispersion and compatibility stability of the cleaning functional material and other components in the protective layer coating solution, preventing rapid stratification or precipitation. The catalyst catalyzes the cross-linking and strengthening reaction between the first film-forming material and the second film-forming material, accelerating the reaction rate without requiring specialized reaction environment conditions, reducing production process steps, and improving production efficiency.

[0023] Preferably, the mass percentage of the anti-settling agent in the raw materials for preparing the protective layer is 0.2-2%, and / or the mass percentage of the catalyst in the raw materials for preparing the protective layer is 0.1-2%, and / or the mass percentage of the lubricant in the raw materials for preparing the protective layer is 3-15%.

[0024] Preferably, the anti-settling agent is at least one of a silane coupling agent, a titanate coupling agent, an organic bentonite, polyacrylamide, and colloidal cellulose.

[0025] Preferably, the catalyst is a rare earth metal oxide catalyst.

[0026] More preferably, the catalyst is at least one of cerium oxide, lanthanum oxide, and molybdenum oxide.

[0027] More preferably, the specific surface area of ​​the catalyst is ≥20m 2 / g. A larger specific surface area can ensure better catalytic activity of the catalyst.

[0028] Preferably, the lubricant is at least one of paraffin wax, montan wax, palm wax, Fischer-Tropsch wax, polyethylene wax, polytetrafluoroethylene wax, fatty acid metal salt, fatty acid amide, stearic acid, diethylene stearate metal salt, and aqueous emulsion of diethylene stearamide, and / or the melting point of the lubricant is 80-140°C.

[0029] Preferably, the nanofiller is at least one of silicon dioxide, kaolin, alumina, aluminum hydroxide, calcined clay, and bentonite.

[0030] Preferably, the water-based resin is at least one of polyurethane resin, styrene acrylic resin and styrene butadiene resin.

[0031] Preferably, the wetting and leveling agent is at least one of an alkyl sulfonate leveling agent, an organosilicon leveling agent, and a fluorocarbon leveling agent.

[0032] Preferably, the thickener is at least one of methyl cellulose, modified starch, and polyacrylamide.

[0033] Preferably, the acid-base regulator is at least one of ammonia water, sodium hydroxide, acetic acid, and citric acid.

[0034] Preferably, the defoaming agent is at least one of an organosilicon defoaming agent, a fatty acid ester defoaming agent, and a phosphate ester defoaming agent.

[0035] Preferably, the thermal printing material further comprises an adhesive layer and a back coating layer, and the thermal printing material comprises a back coating layer, a substrate, an adhesive layer, a thermal imaging layer, and a protective layer stacked in sequence.

[0036] Preferably, the raw materials for preparing the thermal imaging layer include at least one of a dye dispersion, a developer dispersion, a first aqueous resin, polyvinyl alcohol, a nanofiller, a wetting and leveling agent, and a defoaming agent.

[0037] Preferably, the raw materials for preparing the thermal imaging layer include, by weight, at least one of 15-25 parts of dye dispersion, 40-60 parts of developer dispersion, 5-15 parts of first aqueous resin, 5-15 parts of polyvinyl alcohol, 1-10 parts of nanofiller, 0.5-2 parts of wetting and leveling agent, and 0.5-2 parts of defoaming agent.

[0038] Preferably, the raw materials for preparing the adhesion layer include a second aqueous resin, an adhesion promoter, a thickener and a cross-linking agent.

[0039] Preferably, in parts by weight, the raw materials for preparing the adhesion layer include 80-90 parts of a second aqueous resin, 0.5-5 parts of an adhesion promoter, 2-6 parts of a thickener, and 1-10 parts of a cross-linking agent.

[0040] Preferably, the raw materials for preparing the back coating layer include a third aqueous resin, polymethyl methacrylate particles, an organic silicone lubricant, a cross-linking agent, a surfactant and an ultraviolet absorber.

[0041] Preferably, the raw materials for preparing the back coating layer include, by weight, 50-70 parts of a third aqueous resin, 1-5 parts of polymethyl methacrylate particles, 0.1-2 parts of a silicone lubricant, 1-5 parts of a crosslinking agent, 0.5-3 parts of a surfactant, and 0.5-2 parts of a UV absorber.

[0042] Preferably, the second aqueous resin and the third aqueous resin are each independently selected from at least one of styrene-butadiene latex, styrene-acrylic latex, acrylic resin, polyurethane resin, epoxy resin, polyvinylidene chloride resin, and polyacetate emulsion.

[0043] Preferably, the wetting and leveling agent is at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, an organosilicon wetting and leveling agent, an acetylene glycol wetting and leveling agent, and a fluorocarbon wetting and leveling agent.

[0044] Preferably, the substrate is at least one of paper, non-woven fabric, woven fabric, metal foil, and organic film.

[0045] More preferably, the substrate is an organic film.

[0046] Preferably, the organic film is one of polypropylene (PP), biaxially oriented polypropylene (BOPP), polycarbonate (PC), polyethylene (PE), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polyethylene terephthalate-1,4-cyclohexanedimethanol-non-crystallized polyethylene terephthalate-polyethylene terephthalate-1,4-cyclohexanedimethanol ester (i.e., PETG-APET-PETG three-layer composite polyester, GAG).

[0047] More preferably, the organic film is polyethylene terephthalate (PET).

[0048] More preferably, the organic film is polyethylene terephthalate (PET) with a haze of ≤15%. After coating with PET having low haze, the thermal printing material can have a good transparent appearance.

[0049] Preferably, at least one layer of the thermal printing material contains nanofillers to improve the bonding strength between layers and reduce costs.

[0050] Preferably, the nanofiller is at least one of kaolin, bentonite, talc, calcium carbonate, calcined clay, alumina, aluminum hydroxide, silicon dioxide, titanium dioxide, bentonite, polyacrylic resin particles, polymethyl methacrylate particles, barium sulfate, and magnesium silicate.

[0051] Preferably, the average particle size of the nanofiller is ≤1 μm.

[0052] A second aspect of the present invention provides a method for preparing a thermal printing material.

[0053] A method for preparing a thermal printing material comprises the following steps:

[0054] A protective layer coating liquid is prepared using a first film-forming material, a second film-forming material, and a cleaning functional material, and then a thermal imaging layer coating liquid and a protective layer coating liquid are sequentially coated on one surface of a substrate to obtain the thermal printing material. The thermal printing material includes a substrate, a thermal imaging layer, and a protective layer stacked in sequence.

[0055] Preferably, the thermal printing material further includes an adhesion layer and a back coating layer. The method for preparing the thermal printing material comprises the following steps: sequentially coating an adhesion layer coating liquid, a thermal imaging layer coating liquid, and a protective layer coating liquid on one surface of a substrate, and coating a back coating layer coating liquid on the other surface of the substrate to obtain the thermal printing material.

[0056] Preferably, the adhesion layer coating liquid, the thermal imaging layer coating liquid, the protective layer coating liquid and the back coating layer coating liquid are respectively prepared from the raw materials for preparing the adhesion layer, the thermal imaging layer, the protective layer and the back coating layer.

[0057] Preferably, each time a coating liquid is applied, it is dried and then the next coating liquid is applied.

[0058] Preferably, the drying is thermal drying, and / or the drying temperature is 70-85° C., and / or the drying time is 1-10 min.

[0059] Further preferably, the drying is thermal drying, and / or the drying temperature is 70-80° C., and / or the drying time is 1-5 min.

[0060] Preferably, the coating method is at least one of slide coating, slit coating, curtain coating, blade coating, and film transfer.

[0061] A third aspect of the present invention provides an application of a thermal printing material.

[0062] A thermal printing material is used in the fields of medical imaging, construction engineering, and logistics.

[0063] Compared with the prior art, the present invention has the following beneficial effects:

[0064] The thermal printing material provided by the present invention includes a substrate, a thermal imaging layer and a protective layer stacked in sequence. The raw materials for preparing the protective layer include a first film-forming material, a second film-forming material, and a cleaning functional material. The cleaning functional material includes a rare earth oxide. The first film-forming material is at least one of modified polyvinyl alcohol, styrene acrylic resin, polyurethane resin, polyacrylic resin, styrene maleic anhydride copolymer, and water-based epoxy resin. The second film-forming material is a carbonyl compound and / or an amino compound. Rare earth oxides are added to the protective layer of the thermal printing material as a cleaning material. The rare earth oxides have a chemical mechanical polishing effect. During the printing process, the protective layer is the outermost layer and is in direct contact with the thermal print head. Therefore, while successfully completing printing, the thermal print head can also be cleaned, removing foreign matter (including dust, impurities, colloids, coating debris, softened coating, etc.) attached to the thermal print head. The cleaning effect is good (the results of the print head sticking test show that less than 2% of the thermal print head surface has adhered matter), avoiding secondary contamination of the thermal print head, allowing the thermal print head to remain clean for a long time. While completing the cleaning, the printing performance of the thermal print head and the output information image effect of the thermal print head are not affected. The heat generation is uniform, the imaging is good, and the service life of the thermal print head is extended (the cleaned thermal print head can complete more than 5,000 prints without surface scratches). In addition, the thermal printing material of the present invention has good water resistance (water resistance test number of times ≥50 times), scratch resistance and wear resistance, and good permeability (haze 36.7-61.5%). The thermal printing material of the present invention can also replace manual cleaning and maintenance work, offering high cleaning precision, eliminating blind spots, and reducing labor costs. It eliminates the need for additional cleaning consumables, preventing the introduction of new impurities or contaminants into the printing equipment. Furthermore, it requires no downtime for maintenance, enabling continuous, uninterrupted operation. The thermal printing material provided by the present invention meets the application requirements of high-end thermal film for medical imaging, featuring a highly transparent appearance (haze 36.7-61.5%), clear images, high density, and no scratches. DETAILED DESCRIPTION

[0065] In order to make the technical solution of the present invention more clearly understood by those skilled in the art, the following examples are given for illustration. It should be noted that the following examples do not limit the scope of protection claimed by the present invention.

[0066] Unless otherwise specified, the raw materials, reagents, or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0067] The raw materials involved in the present invention are:

[0068] Polyurethane resin: Model RU-086, purchased from Stahl.

[0069] Adhesion enhancer: Model HY-6030, purchased from Huiyan New Materials.

[0070] Unless otherwise specified, the parts referred to in the present invention are parts by mass.

[0071] Example 1

[0072] A thermal printing material comprises a back coating layer, a substrate, an adhesive layer, a thermal imaging layer and a protective layer stacked in sequence. The protective layer is prepared from raw materials comprising a first film-forming material, acetoacetyl-modified polyvinyl alcohol cooking liquid, a second film-forming material, a polyamide epichlorohydrin resin and a cleaning functional material, wherein the cleaning functional material comprises cerium oxide and zirconium oxide.

[0073] The method for preparing the above-mentioned thermal printing material comprises the following steps:

[0074] 1. Adhesion layer coating liquid: Mix 89 parts of polyurethane resin (RU-086), 2 parts of adhesion promoter (HY-6030), 4 parts of methyl cellulose thickener, and 5 parts of carbodiimide crosslinker; then add deionized water as a medium to dilute to a solid content of 10%, stir and mix evenly to prepare an adhesion layer coating liquid.

[0075] 2. Thermal imaging layer coating liquid: Mix 22 parts of dye dispersion, 50 parts of developer dispersion, 10 parts of polyvinyl alcohol, 10 parts of styrene-butadiene latex, 1.5 parts of defoamer, 1.5 parts of wetting and leveling agent, and 5 parts of calcium carbonate; then add deionized water as a medium to dilute to a solid content of 15%, and stir to mix thoroughly to prepare the adhesion layer coating liquid;

[0076] Among them, the dye dispersion used above is: PVA-205MB polyvinyl alcohol 4 parts, dyes (Shanghai Jikang ODB-22 3 parts, Shanghai Jikang D-5 6 parts, Shenyang Chemical GN-169 4 parts), aliphatic phosphate 0.8 parts (France Centron) and an appropriate amount of water are mixed, stirred for 30 minutes, and then put into a ball mill and ground to an average particle size of less than or equal to 0.45 μm. The mixture is then taken out; the mixture is transferred to an insulation tank, heated to 95°C, maintained at 95°C for heat treatment for 1.5 hours, cooled naturally, and diluted with deionized water to a mass concentration of 30% to prepare a dye dispersion;

[0077] Color developer dispersion: Mix 4 parts of PVA-203 polyvinyl alcohol, 33 parts of bisphenol A color developer, 1 part of aliphatic phosphate aqueous solution (Pioneer, France), 0.1 part of defoamer ET-001 and an appropriate amount of water, stir for 30 minutes, and then put into a ball mill and grind until the average particle size is less than or equal to 0.3 μm. Then take out; transfer to an insulation tank, heat to 75°C, maintain 75°C for heat treatment for 5.5 hours, cool naturally, and dilute with deionized water to a mass concentration of 30% to prepare a color developer dispersion.

[0078] 3. Protective layer coating liquid:

[0079] (1) 20 parts of acetoacetyl modified polyvinyl alcohol cooking liquid (first film-forming material, Z200, Mitsubishi Chemical, degree of polymerization 2000, degree of alcoholysis 99%), 2 parts of titanate coupling agent (anti-settling agent, Tyzoer 371, Dofukate) and deionized water were mixed and stirred for 10 minutes. Then, 8 parts of cerium oxide (cleaning functional material, Jingrui New Materials, average particle size 50 nm) and 2 parts of zirconium oxide (R80F, Jingrui New Materials, average particle size 80 nm) were added and stirred for 10 minutes. The mixture was transferred to a ball mill and circulated for grinding and dispersion for 30 minutes to prepare a pre-dispersion liquid.

[0080] (2) The pre-dispersion prepared above, 40 parts of Z200 cooking liquid, 8 parts of zinc stearate F930, 5 parts of nano-silica dispersion A30, 10 parts of polyurethane resin PU8019, 2 parts of wetting and leveling agent DC67, 1 part of defoamer SN522, 2 parts of polyamide epichlorohydrin resin (second film-forming material), and deionized water were mixed and homogenized for 40 minutes to adjust the solid content of the protective layer coating liquid to 10%. The protective layer coating liquid was allowed to stand for 6 hours. The liquid was milky white and slightly yellow, uniform, without stratification or precipitation.

[0081] 4. Back coating liquid: Mix 64 parts of acrylic resin, 25 parts of polyurethane resin, 3 parts of silicon dioxide, 0.5 parts of silicone slip agent, 3 parts of polymethyl methacrylate particles, 2 parts of crosslinking agent, 1.5 parts of surfactant, and 1 part of ultraviolet absorber, then add deionized water as a medium to dilute to a solid content of 10%.

[0082] 5. Apply the adhesion layer coating liquid on the front of the PET substrate with a coating amount of 10mL / m 2 After coating, heat drying was carried out at 80℃ for 5min. Then the thermal imaging layer coating liquid was applied with a coating amount of 250mL / m 2 After coating, heat drying is carried out. Then apply protective layer coating liquid with a coating amount of 80mL / m 2 After coating, heat drying is performed to obtain a semi-finished thermal printing material. Finally, a back coating liquid is applied to the back of the semi-finished thermal printing material, with a coating amount of 20 mL / m 2 After coating, heat drying is performed to obtain thermal printing materials.

[0083] Example 2

[0084] A thermal printing material, which differs from Example 1 in that the amount of cerium oxide in the protective layer coating liquid is increased to 13 parts. The protective layer coating liquid is left to stand for 6 hours, and the liquid is milky white and slightly yellow, uniform, without stratification or precipitation.

[0085] Example 3

[0086] A thermal printing material, which differs from Example 1 in that the amount of cerium oxide in the protective layer coating liquid is reduced to 3 parts, and zirconium oxide is not added. After the protective layer coating liquid is allowed to stand for 6 hours, the liquid is milky white with a slightly yellowish consistency, without stratification or precipitation.

[0087] Example 4

[0088] A thermal printing material, which differs from Example 1 in that the amount of polyamide epichlorohydrin resin (second film-forming material) in the protective layer coating liquid is increased to 4 parts. After the protective layer coating liquid is allowed to stand for 6 hours, the liquid is milky white with a slightly yellowish consistency, without stratification or precipitation.

[0089] Example 5 (using large particle size cerium oxide)

[0090] A thermal printing material, different from Example 1, in that the cerium oxide with an average particle size of 50 nm in the protective layer coating liquid is replaced with cerium oxide with an average particle size of 1 μm. After the protective layer coating liquid was allowed to stand for 6 hours, the liquid was milky white with a slightly yellowish consistency, without any delamination or precipitation.

[0091] Example 6 (without adding anti-settling agent)

[0092] A thermal printing material, which differs from Example 1 in that no titanate coupling agent (anti-settling agent) is added to the protective layer coating liquid. The protective layer coating liquid is left to stand for 6 hours, and the upper layer of the liquid is transparent and clear, while the lower layer is milky white and slightly yellow, with obvious stratification.

[0093] Comparative Example 1 (excluding cerium oxide)

[0094] A thermal printing material, which differs from Example 1 in that 8 parts of cerium oxide in the protective layer coating liquid are replaced with 8 parts of zirconium oxide. The protective layer coating liquid is allowed to stand for 6 hours, and the liquid is milky white with a slightly yellowish consistency, without stratification or precipitation.

[0095] Comparative Example 2 (without adding the second film-forming material)

[0096] A thermal printing material, which differs from Example 1 in that no polyamide epichlorohydrin resin (second film-forming material) is added to the protective layer coating liquid. The protective layer coating liquid is left to stand for 6 hours, and the liquid is milky white and slightly yellow, uniform, without stratification or precipitation.

[0097] Product effect testing

[0098] 1. Test method

[0099] Haze: Tested using the HT-100 Haze / Transmittance Meter. Low haze indicates good transparency and a clear appearance; high haze indicates poor transparency.

[0100] Print head sticking: Use a magnifying glass to observe the thermal printhead heater for molten sticky material, solid sticky material, or other foreign matter adhering to the surface. The less sticky material on the thermal printhead heater, the better the print quality; vice versa. The degree of print head sticking is graded from "None - Mild - Moderate - Severe": "None" indicates less than 2% of the thermal printhead surface has sticky material; "Mild" indicates 2-5% of the thermal printhead surface has sticky material; "Moderate" indicates 6-10% of the thermal printhead surface has sticky material; and "Severe" indicates more than 10% of the thermal printhead surface has sticky material.

[0101] Surface Scratches: Observe the surface of the thermal printing material under reflected light to check for small scratches in the same direction as the printing, which may have broken through the protective layer. Then, observe the image under translucent light to see if any black or white streaks appear, disrupting the image quality. Fewer scratches indicate better quality; fewer indicate poor quality. Scratches are graded on a scale of "none" to "mild" to "moderate" to "severe": "none" indicates no scratches or black or white streaks; "mild" indicates 1-2 scratches; "moderate" indicates 3-10 scratches; and "severe" indicates more than 10 scratches or visible black or white streaks.

[0102] Water resistance: Rub a medical cotton swab soaked in water back and forth across the surface of the thermal printing material. Count the number of times the protective layer is damaged. One back and forth rub is counted as one rub.

[0103] Printing performance: Select an HQ-760DY or HQ-460DY medical thermal imaging printer with moderate or severe print head sticking to continuously print 5 sheets of thermal printing material.

[0104] Delamination: Place approximately 200 mL of the newly prepared protective coating solution in a beaker or graduated cylinder and let it stand for 6 hours. Observe the appearance of the coating solution. If the coating solution remains uniformly milky white with a slight yellowish hue, there is no delamination. If, after standing, the coating solution exhibits distinct demarcations, with the upper layer being relatively clear and the lower layer being a slightly darker milky white with a slight yellowish hue, there is delamination.

[0105] Continuous printing: After completing 5 consecutive prints, confirm the cleaning effect and continue printing continuously until surface scratches appear on the surface of the thermal printing material, or when continuous printing reaches 5,000 sheets.

[0106] 2. Test results

[0107] The performance test results of each embodiment and comparative example are shown in the following table.

[0108] Table 1 Performance test results of thermal printing materials of various embodiments and comparative examples

[0109]

[0110]

[0111] As can be seen from Table 1, Examples 1-6 can perform normal printing even when using thermal print heads with sticking (serious sticking before printing). Moreover, the thermal print heads can be cleaned while printing, and the cleaning effect is significant. The sticking degree after printing is greatly reduced (less than 2% of the thermal print head surface has adhered matter), and the printing effect is not affected. There are no scratches after printing, and the number of water resistance tests is ≥50 times. Moreover, the thermal print heads of Examples 1-5 can complete printing of more than 5,000 sheets without surface scratches after cleaning, and the haze is 36.7-61.5%. The above results demonstrate that the protective layer of the thermal printing material of the present invention has undergone a complete crosslinking reaction and exhibits excellent surface water resistance. Furthermore, the thermal printing materials of Examples 1-4 exhibit good permeability and low haze, facilitating image observation in medical applications. The addition of cerium oxide to the protective layer provides a superior cleaning effect, effectively removing foreign matter adhering to the heating element of the thermal print head during printing. Furthermore, because cerium oxide also acts as a catalyst, promoting the complete crosslinking reaction between the first and second film-forming materials and improving the protective layer's water resistance and abrasion and scratch resistance, the thermal print head remains clean while the surface of the thermal printing material remains scratch-free, unaffecting image quality. This allows the thermal print head to be cleaned while performing normal printing. Therefore, the thermal printing material provided by the present invention can meet the requirements of long-term, continuous, and uninterrupted operation.

[0112] Compared with Example 3 (which does not contain zirconium oxide), Example 1 has a higher cleaning efficiency due to the higher cerium oxide content in Example 3, but the cost is also increased. However, the cleaning effect of Example 1 can also meet the requirements. At the same time, the use of cerium oxide and other oxides can reduce costs and can better remove both large and small particles of adhesion (cerium oxide is more suitable for removing small particles of adhesion in precision structures, while other oxides are more suitable for removing larger particles of adhesion. Small particles are defined as adhesion with an average particle size of less than 0.1 mm, and large particles are defined as adhesion with an average particle size of 0.1 mm or greater).

[0113] Compared with Example 1, Example 5 uses large-particle cerium oxide, so the haze of the thermal printing material increases significantly, and the appearance transparency is slightly poor, which is not conducive to the observation of medical images and is not conducive to medical auxiliary diagnosis, and it is difficult to meet the needs.

[0114] Compared to Example 1, Example 6 lacks an anti-settling agent, resulting in delamination of the protective layer coating solution. This deteriorates the dispersion stability of the cleaning functional material and makes the protective layer coating solution prone to stratification and sedimentation upon standing, making mass production of thermal printing materials difficult. This demonstrates that the anti-settling agent ensures good compatibility and dispersion stability of the functional material, cerium oxide, allowing the protective layer coating solution to maintain uniformity and stability over a long period of time, thus ensuring optimal mass production.

[0115] Compared to Example 1, the thermal printing material in Comparative Example 1 lacks its cleaning function due to the lack of cerium oxide, making it unable to clean adherent material from the thermal printhead. Consequently, the thermal printing material still suffers from severe sticking after printing. Furthermore, the thermal printing material's water resistance is also reduced. This is because the lack of cerium oxide results in a lack of catalyst. Therefore, after the coating liquid of the thermal printing material dries, the cross-linking reaction between the film-forming materials in the protective layer is not catalyzed, resulting in low reaction efficiency and incomplete cross-linking, which in turn leads to poor water resistance in the protective layer.

[0116] Compared with Example 1 and Example 4, in Comparative Example 2, due to the lack of the second film-forming material, no cross-linking reaction occurs in the first film-forming material, and the water resistance of the protective layer is poor. At the same time, the protective layer does not obtain the strengthening effect brought by the cross-linking reaction, and the scratch resistance and wear resistance are poor. Scratch problems are prone to occur, and long-term continuous work cannot be carried out.

Claims

1. A thermal printing material, characterized in that: The invention comprises a substrate, a thermal imaging layer and a protective layer stacked in sequence, wherein the raw materials for preparing the protective layer comprise a first film-forming material, a second film-forming material and a cleaning functional material, wherein the cleaning functional material comprises a rare earth oxide, and the first film-forming material is at least one of modified polyvinyl alcohol, styrene acrylic resin, polyurethane resin, polyacrylic resin, styrene maleic anhydride copolymer and water-based epoxy resin, and the second film-forming material is a carbonyl compound and / or an amino compound.

2. The thermal printing material according to claim 1, characterized in that: The mass percentage of the rare earth oxide in the cleaning functional material is 50-100%.

3. The thermal printing material according to claim 1, characterized in that: The rare earth oxide is at least one of cerium oxide, lanthanum oxide, praseodymium oxide, neodymium oxide, and yttrium oxide.

4. The thermal printing material according to claim 3, characterized in that: The rare earth oxide is cerium oxide.

5. The thermal printing material according to claim 4, characterized in that: The average particle size of the cerium oxide is ≤100 nm, and / or the specific surface area of ​​the cerium oxide is ≥20 m 2 / g.

6. The thermal printing material according to claim 1, characterized in that: The cleaning functional material further includes other oxides, and the other oxides are at least one of silicon oxide, aluminum oxide, and zirconium oxide.

7. The thermal printing material according to claim 6, characterized in that: The mass percentage of other oxides in the cleaning functional material is 0-20%, and / or the average particle size of the other oxides is ≤100 nm.

8. The thermal printing material according to claim 1, wherein: Calculated by mass percentage, the raw materials for preparing the protective layer include 50-80% of the first film-forming material, 0.05-8% of the second film-forming material, and 1-20% of the cleaning functional material.

9. The thermal printing material according to claim 1, characterized in that: The first film-forming material is at least one of itaconic acid-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, and silane-modified polyvinyl alcohol, and / or the polymerization degree of the first film-forming material is 1700-3500, and / or the alcoholysis degree of the first film-forming material is ≥88%.

10. The thermal printing material according to claim 1, characterized in that: The second film-forming material is at least one of polyamide polyamine epichlorohydrin resin, polyaziridine, polycarbodiimide, adipic acid dihydrazide, hydroxymethyl melamine resin, and aldehyde compounds.

11. The thermal printing material according to claim 1, characterized in that: The thermal printing material further comprises an adhesive layer and a back coating layer, and the thermal printing material comprises a back coating layer, a substrate, an adhesive layer, a thermal imaging layer and a protective layer which are stacked in sequence.

12. The method for preparing a thermal printing material according to any one of claims 1 to 11, characterized in that: The steps include: A protective layer coating liquid is prepared using a first film-forming material, a second film-forming material, and a cleaning functional material, and then a thermal imaging layer coating liquid and a protective layer coating liquid are sequentially coated on one surface of a substrate to obtain the thermal printing material. The thermal printing material includes a substrate, a thermal imaging layer, and a protective layer stacked in sequence.

13. The preparation method according to claim 12, characterized in that The thermal printing material also includes an adhesion layer and a back coating layer. The preparation method of the thermal printing material includes the following steps: sequentially coating an adhesion layer coating liquid, a thermal imaging layer coating liquid, and a protective layer coating liquid on one surface of a substrate, and coating a back coating layer coating liquid on the other surface of the substrate to obtain the thermal printing material.

14. Use of the thermal printing material according to any one of claims 1 to 11 in the fields of medical imaging, construction engineering, and logistics.

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