A high-sensitivity, moisture-resistant, heat-resistant thermosensitive microcapsule dispersion, its preparation method, and thermosensitive film.

Abstract

This invention discloses a high-sensitivity, moisture- and heat-resistant thermosensitive microcapsule dispersion, its preparation method, and a thermosensitive film. The preparation method includes the following steps: C1, oil phase preparation: heating the microcapsule core component containing an organic solvent until completely dissolved; C2, aqueous phase preparation: dissolving a water-soluble protective colloid in water to prepare a 3-15% (w / w) aqueous solution; C3, capsule dispersion preparation: adding the oil phase to the aqueous phase under high-speed emulsification conditions, emulsifying for 2-10 minutes, raising the temperature to 40-60°C, and reacting for 3-6 hours. The key feature is that the hydrophobic thermoplastic resin of this invention, with a TG content in the range of 40-70°C, is added in the oil phase preparation step of the microcapsule dispersion. The thermosensitive microcapsule dispersion of this invention is applied to medical thermosensitive films, with a simple manufacturing process, high film sensitivity, and good storage stability under high temperature and high humidity conditions, preventing blackening.

Description

Technical Field

[0001] This invention belongs to the field of medical thermal film technology, specifically relating to a high-sensitivity, moisture-resistant, heat-resistant thermal microcapsule dispersion, its preparation method, and thermal film. Background Technology

[0002] Traditional information recording primarily uses silver halide materials, which are highly efficient recording materials that integrate information reception, storage, and reproduction. They offer high image resolution and relatively simple recording devices. However, silver halide materials use precious silver as raw material, resulting in complex production processes. Furthermore, the production and use of these materials generate large amounts of wastewater containing heavy metals, polluting the environment. The technical requirements for processing and transmission are also stringent, making them unsuitable for the demands of social development.

[0003] With continuous technological advancements, thermal recording materials are gradually replacing traditional silver halide recording materials. These thermal recording materials primarily utilize the chemical reaction between electron-donating colorless dyes and electron-accepting compound developers in a high-temperature molten state to form recorded images. This type of thermal recording material has significant advantages over traditional silver halide recording materials. To better improve the separation and development of colorless dyes and developers, US patents US4446376, US4411979, US4682194, and US4742043 propose a thermal recording material using microcapsules. These technologies are characterized by forming microcapsules from dye precursors and / or developers. Each microcapsule includes a capsule wall and a core. The colorless dye or developer and related components are located in the core, and the capsule wall is made of polyurethane or polyurea. When heated to a certain temperature, reaching the glass transition temperature of the capsule wall, the permeability of the capsule wall increases, allowing the developer and colorless dye to mix rapidly and form an image. This type of thermal material has been widely used in thermal film technology.

[0004] In practical applications, thermal film may not be used up quickly after opening the packaging. The printer's film cassette is not completely sealed, meaning the film is exposed to the environment for a certain period of time. The top few sheets are particularly affected by the environment. In the hot and humid weather of the south, prolonged exposure can cause reactions in the capsule, thermal layer, and protective layer, leading to a decrease in barrier properties. This can cause the colorless thermal dyes and developers inside and outside the capsule to undergo unconventional low-temperature color development, resulting in the entire film developing a darker, unreflective color and failing to properly reflect diagnostic images.

[0005] Meanwhile, the sensitivity of thermal film is also a crucial indicator. It needs to record multi-layered, high-capacity image information. The imaging mechanism of thermal film involves selectively heating the imaging layer using a thermal printhead of a specific geometry. Temperature changes adjust the permeability of the microcapsule walls to obtain the image. After the temperature decreases, the microcapsule walls harden again, losing their permeability, thus fixing the image and improving image stability. It is a purely thermal recording material. During the use of thermal materials, the printhead needs precise adjustment and control of temperature and heat transfer to provide satisfactory image quality and ensure the reproducibility of the same image in multiple printing processes. Therefore, it requires precise control and rapid adjustment of the printhead temperature, providing sufficient heat for the permeation process and color reaction. Sensitivity is a critical indicator, and lower printhead operating temperatures are more beneficial to printhead lifespan and stability; in other words, higher film sensitivity is always better.

[0006] To address the issue of poor color development in thermal films under high temperature and humidity conditions, methods have been employed, including improving the water vapor barrier properties of the capsule, heat-sensitive layer, and protective film, and increasing the boiling point of the developer. Increasing the thickness of the capsule wall, heat-sensitive layer, and protective layer, as well as enhancing water resistance, have also been implemented. However, due to technical limitations, these methods only achieve a certain level of effectiveness. When the ambient water vapor concentration reaches a certain level, effective barrier properties are still insufficient, which also affects color development efficiency and reduces sensitivity. Increasing the boiling point of the developer also reduces film sensitivity; neither is the optimal solution. A solution is needed for thermal films that simultaneously offer high sensitivity and high color development efficiency.

[0007] Chinese patent application number CN200610012671 describes a thermal recording material. Its main function is to add a heterogeneous coating between two polyvinyl alcohol (PVA) coatings, one protective layer and one recording layer. This significantly reduces the penetration rate of harmful gases or water vapor into the coating, extending the effective preservation time of images and films. However, adding this interlayer increases cost and makes the manufacturing process more complex.

[0008] Therefore, a thermal film is needed that has a simple manufacturing process, high thermal sensitivity, and does not cause darkening or blackening under high temperature and humidity conditions, while also having good resistance to damp heat. Summary of the Invention

[0009] To solve the above-mentioned problems, the present invention addresses the technical issues by incorporating the following unprecedented new concept: during the preparation of the thermosensitive microcapsule dispersion, the hydrophobic thermoplastic resin of the present invention is added in the oil phase step. The resin, with a TG value in the range of 40-70°C, functions as a sensitizer to enhance sensitivity and also exhibits better moisture barrier properties.

[0010] The means to solve the technical problem: The present invention is a high-sensitivity, moisture-resistant, heat-sensitive microcapsule dispersion and its preparation method.

[0011] A highly sensitive, humid heat-resistant, and thermosensitive microcapsule dispersion, comprising a microcapsule core and an aqueous dispersion phase, wherein the microcapsule core comprises a colorless dye, a color developer, a thermoplastic resin, an isocyanate, and a solvent, wherein the thermoplastic resin is one or more of the following: homopolymer or copolymer of olefins or chlorinated olefins, homopolymer or copolymer of acrylic acid and its esters or methacrylic acid and its esters, copolymer of olefins or chlorinated olefins and acrylic acid and its esters or methacrylic acid and its esters, and linear polyester resin, with a TG value in the range of 40-70°C.

[0012] The preparation method includes the following steps: C1, oil phase preparation: heating the microcapsule core component containing organic solvent until completely dissolved; C2, aqueous phase preparation: dissolving the water-soluble protective colloid in water to prepare an aqueous solution with a mass concentration of 3-15%; C3, capsule dispersion preparation: adding the oil phase to the aqueous phase under high-speed emulsification conditions, emulsifying for 2-10 minutes, raising the temperature to 40-60℃, and reacting for 3-6 hours. The microcapsule core component contains a hydrophobic thermoplastic resin with TG in the range of 40-70℃, added in the oil phase preparation step of the microcapsule dispersion.

[0013] The hydrophobic thermoplastic resin includes homopolymers or copolymers of olefins or chlorinated olefins, homopolymers or copolymers of acrylic acid and its esters or methacrylic acid and its esters; copolymers of olefins or chlorinated olefins and acrylic acid and its esters or methacrylic acid and its esters; one or more linear polyester resins, with a TG in the range of 40-70°C.

[0014] The oil phase component of the colorless dye microcapsule dispersion includes colorless dye, ultraviolet absorber, isocyanate, thermoplastic resin, and solvent.

[0015] The oil phase component of the color developer microcapsule dispersion includes a color developer, a hydrophobic thermoplastic resin, an isocyanate, and a solvent.

[0016] The microcapsule dispersion has a microcapsule particle size of 0.4-1.0 μm.

[0017] The thermal film of the thermal microcapsule dispersion of the present invention comprises (a) a transparent support, (b) a thermal recording layer containing colorless dye microcapsules and a color developer formed on the transparent support, and (c) a protective layer containing pigments and binders as main components formed on the thermal recording layer.

[0018] 1. Thermal recording layer

[0019] The thermal recording layer is composed of colorless dye microcapsule dispersions, color-developing agent thermal microcapsule dispersions or grinding dispersions, binders, and additives. The microcapsule dispersions consist of capsules, surfactants, glues, binders, and water. The microcapsule structure includes a capsule wall and a core. The core of the colorless dye microcapsule dispersion includes colorless dyes, stabilizers, thermoplastic resins, and solvents. The core of the color-developing agent microcapsule dispersion includes color developers, thermoplastic resins, and solvents. The capsule wall components include polyurea or polyurethane. A detailed description of each component follows.

[0020] (1) The hydrophobic plastic resin of the present invention

[0021] The colorimetric reaction between the colorless dye and the developer is irreversible. When not in use, the capsule wall and protective film act as a barrier, preventing the reaction. The glass transition temperature of the capsule wall is 70℃~200℃. During printing, the capsule wall softens upon heating, and the developer melts and permeates through the capsule wall, triggering a colorimetric reaction. The degree of color development varies depending on the printer temperature, forming an image. However, in practical applications, the presence of moisture in the air, especially under high temperature and humidity conditions, leads to a higher water vapor concentration. This water vapor affects the hydrophilic components in the capsule wall and protective layer, causing a decrease in the permeation temperature, resulting in a heavier color than normal, or even complete discoloration that prevents image display. Furthermore, in high temperature and humidity environments, the thermal film's storage stability deteriorates, making it prone to blackening. The hydrophobic plastic polymer of this invention cannot be added to the aqueous phase as a capsule wall component using conventional methods because it dissolves in a solvent. The capsule core component contains solvents... The agent, along with the colorless dye component, is added to the capsule core component. During the polyurethane or polyurea capsule wall polymerization reaction to make the capsule, it partially forms part of the capsule wall. Because of its hydrophobic properties, it has a certain water-blocking effect. It also partially combines with the colorless dye component. Since the TG of the hydrophobic plastic resin of this invention is controlled at 40-70℃, it has a similar effect to a sensitizer. At the same time, when not in use, the temperature is below 40-70℃. Under normal conditions, the ambient temperature is below this temperature, and it exists in the microcapsule in solid form. In this way, it can better ensure that the dye precursor and ultraviolet absorber in the microcapsule will not cause the recording material to fog up, reduce sensitivity, or deteriorate image quality due to slow permeation.

[0022] The hydrophobic plastic resins of the present invention include homopolymers or copolymers of olefins or chlorinated olefins, homopolymers or copolymers of acrylic acid and its esters or methacrylic acid and its esters; copolymers of olefins or chlorinated olefins and acrylic acid and its esters or methacrylic acid and its esters; and linear polyester resins.

[0023] The polymer monomers of homopolymers or copolymers of olefins or chlorinated olefins include ethylene, propylene, 1-butene, 3-methyl-1-butene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-4-butadiene, isoprene, 1,2-butadiene, vinyl chloride, vinylidene chloride, etc.

[0024] The monomers for the homopolymer or copolymer of acrylic acid and its esters or methacrylic acid and its esters include water-soluble and water-insoluble monomers. The water-soluble monomers include itaconic acid, acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, maleic anhydride, 3-hydroxypropyl acrylate, acrylamide, methacrylamide, and 2-acrylamido-2-methylbenzenesulfonic acid. The water-insoluble monomers include methyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, isobornyl acrylate, isobornyl methacrylate, isooctyl acrylate, isooctyl methacrylate, ethyl acrylate, ethyl methacrylate, acrylonitrile, methacrylonitrile, vinyl acetate, 2-methoxyethyl acrylate, octadecyl acrylate, lauryl acrylate, etc.

[0025] A copolymer of an olefin or chlorinated olefin and acrylic acid and its esters or methacrylic acid and its esters, copolymerized using one or more of the two monomers of the above different types.

[0026] The polymerization method employs free radical polymerization, where the initiator generates free radicals under the action of heat or light, which initiates the chain polymerization of monomers. The molecular weight is controlled by chain transfer agents, and the TG of the polymer is controlled at 40-70℃ by the softness and hardness of the monomers.

[0027] Linear polyester resins are produced by stepwise polymerization of linear polyols or polyamines and polyacids to remove water, resulting in a plastic linear polyester resin. It exhibits excellent flexibility and includes both saturated and unsaturated polyesters. If the polyol, polyamine, or polyacid has an unsaturated carbon-carbon double bond structure that has not been opened during polymerization, it is an unsaturated polyester. Unsaturated polyesters can undergo cross-linking reactions later. If neither the polyol nor the polyacid has an unsaturated carbon-carbon double bond structure, the synthesized product is an unsaturated polyester. Both saturated and unsaturated polyesters can be used in this invention.

[0028] The linear polyester resin polymeric acid monomers include: oxalic acid, maleic acid, malonic acid, succinic acid, glutaric acid, adipic acid, hematoxylin and phthalic acid, as well as their hydrogen-substituted derivatives and corresponding acid anhydrides.

[0029] The polyol monomers used in the polymerization of linear polyester resins include: ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,7-heptanediol, 1,8-octanediol, propylene glycol, 1,3-dihydroxybutane, 2,2-dimethyl-1,3-propanediol, 2,5-hexanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanediol, dihydroxycyclohexane, diethylene glycol, phenylethylene glycol, bisphenol A, bisphenol AP, etc.

[0030] The polyamine monomers used in linear polyester polymerization include: ethylenediamine, propylenediamine, triethylenediamine, butanediamine, pentanediamine, hexamethylenediamine, p-phenylenediamine, m-phenylenediamine, triethyltriamine, triethyltetramine, diethylaminopropylamine, etc.

[0031] The polycondensation reaction of linear polyesters is a reversible step-growth polymerization reaction, an interfunctional polymerization reaction. Low-molecular-weight byproducts such as water, alcohols, and amines are produced during the reaction. The molecular weight gradually increases with increasing reaction time, but the monomer conversion rate is almost independent of time. Based on reaction conditions, it can be classified into four types: melt polycondensation, solution polycondensation, interfacial polycondensation, and solid-state polycondensation. Based on the raw materials used, it can be classified into three types: homopolymerization, mixed polycondensation, and copolymerization.

[0032] The olefins in the hydrophobic plastic resin structural units of the present invention are nonpolar groups. The addition of halogen atoms of halogenated olefins increases moisture resistance and resistance to acid and alkali solvents. The ester structures formed by acrylate monomers, acids and alcohols are not hydrophilic groups. After polymerization to form resin, they do not have hydrophilic groups, are hydrophobic, do not easily form hydrogen bonds, are not conducive to water conduction, and are beneficial to blocking moisture in high temperature and high humidity environments.

[0033] The above-mentioned hydrophobic plastic resins can be synthesized in-house, and commercially available products are currently available. Examples include:

[0034] Rohm and Haas: B44, B48N, B64, B66, B72, A21, etc.; Nippon Paper: DX530P, 1122S, etc.

[0035] Polymers such as 892ls, F-2P, and 10275, SK Polymer (Korea), ES420, ES100, ES100, ES120, ES410, and ES450, and Toyobo Resin (Japan) DX526P, DX530P, VYLON103, 220, 226, 240, 270, and 290 are all applicable to this invention. No particular limitation is placed on any polymer that meets the TG (thermal conductivity) requirement within the 40-70°C range and is commercially available in the plastics industry.

[0036] Dosage: The hydrophobic plastic resin of this invention accounts for 5-15% of the mass of the isocyanate. Dosage exceeding 15% will affect the formation of the isocyanate capsule wall and also increase the particle size of the capsule. Dosage less than 5% has little effect on blocking moisture.

[0037] (2) Colorless dyes, color developers, stabilizers and solvents

[0038] There are no particular restrictions on colorless dyes, color developers, stabilizers, and solvents; they can be any type used in the fields of medical thermal films and thermal paper. Colorless dyes and color developers are sufficient to ensure that the resulting recording material can develop color under heating conditions. Stabilizers improve the preservation stability of the recorded image. Solvents are used to dissolve other components to form a stable solution and can also reduce viscosity and decrease capsule particle size.

[0039] Colorless dyes contained in thermal recording layers include types such as fluoranes, lactones, triarylmethanes, thiazides, phenazines, phenothiazines, or triarylpyridines. Specific examples include: 3-diethylamino-7-chlorofluorane, 3-(N-ethyl-p-toluamino)-7-methylfluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-(N-ethyl-N-isopentyl)amino-7-phenoxyfluorane, 3-diethylamino-6,8-dimethylfluorane, 3-di(n-butyl)amino-6-methyl-7-bromofluorane, 3-toluamino-7-methylfluorane, 3-toluamino-7-ethylfluorane, 2-(N-acetylanilino)-3-methyl-6-di(n-butyl)aminofluorane, 2-(N-benzoylanilino)-3-methyl-6-di(n-butyl)aminofluorane, 2-(N-butoxycarbonyl-1-methyl)fluorane, and 2-(N-butoxycarbonyl-1-methyl)fluorane. (N-methylaniline)-3-methyl-6-di(n-butyl)aminofluorane, 2-(N-methylaniline)-3-methyl-6-di(n-butyl)aminofluorane, etc. are colorless dyes with red color development;

[0040] 3,3-Bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, 3-(4-diethylamino-2-methylphenyl)-3-(4-dimethylaminophenyl)-6-dimethylaminophthalide, 3-(4-diethylamino-2-ethoxyphenyl)-3-(1-ethyl-2-methylindole-3-yl)-4-azaphthalide, 3-diphenylamino-6-diphenylaminofluorane, 3-(2-methyl-1-n-octylindole-3-yl)-3-(4-diethylamino-2-ethoxyphenyl)-4-azaphthalide are colorless dyes with blue color development; 3-(N-ethyl-N-p-tolylamino)-7-(N-phenyl-N-methylamino)fluorane, 3-(N-ethyl-N-n-hexylamino)-7- Aniline fluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-(o-chloroaniline)fluorane and other green colorless dyes with color development;

[0041] 3,6-Dimethoxyfluorane, 1-(4-n-dodecyloxy-3-methoxyphenyl)-2-(2-quinolinyl)ethylene, 1,3,3-trimethylindoline-2,2'-spiro-6'-nitro-8'-methoxybenzopyran, etc. are yellow colorless dyes with color development.

[0042] 3-Pyrrolidinyl-6-methyl-7-anilinofluorane, 3-Diethylamino-7-(m-trifluoromethylanilino)fluorane, 3-(N-isopentyl-N-ethylamino)-7-(o-chloroanilino)fluorane, 3-(N-ethyl-p-tolueneamino)-6-methyl-7-anilinofluorane, 3-(N-ethyl-N-2-tetrahydrofurfurylamino)-6-methyl-7-anilinofluorane, 3-Diethylamino-6-chloro-7-anilinofluorane, 3-Di(n-butyl)amino-6-methyl-7-anilinofluorane (ODB-2), 3-Di(n-pentyl)amino-6-methyl-7-anilinofluorane, 3-(N-isopentyl-N-ethylamino)-6-methyl-7-anilinofluorane (S-205), 3- (N-hexyl-N-ethylamino)-6-methyl-7-aniline fluorane, 3-di(n-butyl)amino-(2-chloroaniline) fluorane, 3-diethylamino-6-methyl-7-aniline fluorane, 3-diethylamino-6-methyl-7-(3-toluamino) fluorane, 3-diethylamino-6-methyl-7-(2,6-dimethylaniline) fluorane, 3-diethylamino-6-methyl-7-(2,4-dimethylaniline) fluorane, 2,4-dimethyl-6-(4-dimethylaminoaniline) fluorane, etc. are black colorless dyes with color development properties;

[0043] 3,3-bis(4-diethylamino-2-ethoxyphenyl)-4-azaphthalide (GN-2), 3,3-bis[1-(4-methoxyphenyl)-1-(4-dimethylaminophenyl)vinyl-2-yl]-4,5,6,7-tetrachlorophthalide, 3,6-bis(dimethylamino)fluorene-9-spiro-3'-(6'-dimethylamino)phthalide, and 3-[2,2-bis(1-ethyl-2-methylindol-3-yl)vinyl]-3-(4-diethylaminophenyl)phthalide are colorless dyes with strong absorption wavelengths in the near-infrared range.

[0044] Examples of color-developing agents include: 4,4'-isopropylidene diphenol, 4,4'-cyclohexylene diphenol, 2,2'-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxyphenyl)-4-methylpentane, 2,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone (D8), bis(3-allyl-4-hydroxyphenyl) sulfone (TGSH), 4-hydroxy-4'-allyloxydiphenyl sulfone, 4-hydroxy-4'-methyldiphenyl sulfone, bis(p-hydroxyphenyl) acetate butyl acetate, bis(p-hydroxyphenyl) acetate methyl acetate, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, 1,4-bis[α-methyl-α-(4-hydroxyphenyl)-2-(4-hydroxyphenyl)-2-phenylethane, 2,2'-bis ... Phenolic compounds such as [-hydroxyphenyl]ethylbenzene; compounds with sulfonyl and urea groups in the molecule, such as N-(p-toluenesulfonyl)-N-phenylurea, 4,4'-bis(N-p-toluenesulfonylaminocarbonylamino)diphenylmethane, 4,4'-bis[(4-methyl-3-phenoxycarbonylaminophenyl)ureo]diphenyl sulfone, and N-p-toluenesulfonylN'-p-butoxyphenylurea; zinc salts of aromatic carboxylic acids such as 4-(n-octyloxycarbonylamino)salicylate, 4-[2-(p-methylphenoxy)ethoxy]salicylate, 4-[3-(p-toluenesulfonyl)propoxy]salicylate, and 5-[p-(2-p-methoxyphenoxyethoxy)isopropylphenyl]salicylic acid.

[0045] Specific examples of stabilizers include: 4,4'-butylidene bis(6-tert-butyl-3-methylphenol), 2,2'-methylene bis(4-ethyl-6-tert-butylphenol), 2,4-di(tert-butyl)-3-methylphenol, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,1,3-tris(2-methyl-4-hydroxy-5-cyclohexylphenyl)butane, 1,3,5-tris(5-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanuric acid, and other hindered phenols; 4-(2-methyl-1,2-epoxyethyl)diphenyl sulfone, 4-(2-ethyl-1,2-epoxyethyl)diphenyl sulfone, 4-benzyloxy-4'-(2,3-glycidyloxy)diphenyl sulfone, and other diphenyl sulfone-based epoxy compounds; 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2- UV absorbers such as (3'-tert-butyl-5'-methyl-2'-hydroxyphenyl)-5-chlorobenzotriazole, 2-hydroxy-4-benzyloxybenzophenone, and 2-hydroxy-4-octyloxybenzophenone.

[0046] Specific examples of solvents include ethyl acetate, acetone, butyl acetate, isobutylbenzene, ethyl acetoacetate, α-methylnaphthalene, cyclohexanone, or dibutyl phthalate.

[0047] (3) Capsule wall components: The capsule wall components are polyurethane or polyurea, which are obtained by reacting polyisocyanates with polyols or polyamines.

[0048] Specific examples of polyisocyanate compounds include: p-phenylene diisocyanate, 2,6-toluene diisocyanate, 2,4-toluene diisocyanate, naphthalene-1,4-diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, isophorone diisocyanate (IPDI), 1,3-bis(isocyanate methyl)cyclohexane, 3,3'- Dimethyl diphenylmethane-4,4'-diisocyanate, 4,4'-dicyclohexylmethane diisocyanate (HMDI), diphenyl dimethyl-1,4-diisocyanate, tetramethylphenyl dimethylene diisocyanate, 4,4'-diphenylpropane diisocyanate, hexamethylene diisocyanate, 1,2-butanediisocyanate, cyclohexene-1,2-diisocyanate, cyclohexene-1,4-diisocyanate, 4,4',4”-triphenylmethane triisocyanate, toluene-2,4,6-triisocyanate, trimethylolpropane adduct of hexamethylene diisocyanate, trimethylolpropane adduct of 2,4-toluene diisocyanate, trimethylolpropane adduct of xylene diisocyanate, etc.

[0049] Specific examples of polyol compounds include: ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,7-heptanediol, 1,8-octanediol, propylene glycol, 1,3-dihydroxybutane, 2,2-dimethyl-1,3-propanediol, 2,5-hexanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanediol, dihydroxycyclohexane, diethylene glycol, phenylethylene glycol, pentaerythritol, 1,4-di(2-hydroxyethoxy)benzene, 1,3-di(2-hydroxyethoxy)benzene, p-xylenediol, m-xylenediol, 4,4'-isopropylidene diphenol, 4,4'-dihydroxydiphenyl sulfone, etc.

[0050] Examples of polyamine compounds include: ethylenediamine, propylenediamine, butanediamine, pentanediamine, hexamethylenediamine, p-phenylenediamine, m-phenylenediamine, 2,5-dimethylpiperazine, triethyltriamine, triethyltetramine, diethylaminopropylamine, etc.

[0051] Polyisocyanate compounds, adducts of polyisocyanates and polyols, and polyol compounds, etc., are not limited to the aforementioned compounds. In addition, two or more can be used in combination as needed.

[0052] (4) Other components in the microcapsule dispersion

[0053] Other components in the microcapsule dispersion include gums, surfactants, binders, and other additives. Gums, as an important component in the microcapsule dispersion, play a protective role for the colloid. Specific types include hydroxycellulose, polyvinyl alcohol, carboxyl-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, styrene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, and casein, etc.

[0054] This invention does not particularly limit the surfactants used in the coating solution for forming the thermal recording layer. Surfactants include anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants, and can also be silicone-containing and fluorine-containing surfactants. Specific examples include sodium dioctyl sulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl sulfate, fatty acid metal salts, sodium perfluorononenoxybenzenesulfonate (OBS), surfactant 1283, surfactant 1292, BYK-348, etc.

[0055] Examples of adhesives include: oxidized starch, hydroxymethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polyvinyl alcohol, carboxyl-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, styrene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, and casein, as well as hydrophobic adhesives such as polyester resins, polyvinyl acetate resins, polyurethane resins, polyacrylic resins, styrene-butadiene copolymer resins, and mixed styrene-butadiene copolymer resins obtained by copolymerizing styrene monomers and butadiene monomers in an aqueous medium containing polyurethane ionomers.

[0056] Examples of additives include: lubricants such as zinc stearate and calcium stearate; waxes such as polyethylene wax, carnauba wax, paraffin wax, and ester wax; pigments such as kaolin, clay, talc, calcium carbonate, calcined kaolin, titanium dioxide, amorphous silica, and aluminum hydroxide; as well as defoamers, fluorescent whitening dyes, and crosslinking agents.

[0057] (5) Preparation steps of microcapsule dispersion

[0058] Thermosensitive microcapsules can be prepared using any of the existing known chemical methods, such as interfacial polymerization, in-situ polymerization, composite condensation, and phase separation, with in-situ polymerization being preferred. Polyurethane or polyurea is obtained by reacting polyisocyanates with polyols or polyamines. The oil phase is dispersed in an aqueous medium under the protection of a protective colloid, resulting in oily microcapsules dispersed in water. The isocyanate, polyol, or polyamine undergoes polymerization reactions on the outer and inner sides of the capsules, respectively, forming the capsule wall.

[0059] The concentration of the protective colloid determines its viscosity. If the viscosity is too high, emulsification is difficult, resulting in large capsule particle sizes. If the viscosity is too low, effective protection cannot be achieved, and capsules are difficult to form. Different protective colloids require different viscosities, with a suitable range of 3%-15%, preferably 5-10%.

[0060] If the emulsification time is too short, emulsification will be incomplete, resulting in large and uneven particle size. If the emulsification time is too long, it can easily damage the capsule wall and cause coagulation. The appropriate emulsification time is 2-10 minutes.

[0061] The process of temperature increase during capsule wall formation involves the polymerization of isocyanate or isocyanate-containing polyurethane with a curing agent. Higher temperatures result in shorter reaction times. While temperatures above 60°C can shorten the reaction time, the rapid reaction increases the likelihood of defects, affecting capsule wall density. Temperatures below 40°C result in a slow reaction, impacting efficiency. The optimal reaction temperature for capsule formation is between 40-60°C, with a reaction time of 3-6 hours. A reaction time of 6 hours at 40°C and 3 hours at 60°C represents a suitable range.

[0062] To increase the barrier properties of the capsule wall, conventional methods involve adding aqueous resins or emulsions to the aqueous phase and the heat-sensitive layer formulation during capsule manufacturing. Curing agents can be added to further enhance barrier properties and strength. In this invention, a hydrophobic thermoplastic resin with a TG value in the range of 40-70°C is added during the oil phase preparation step of the microcapsule dispersion. This component, forming the capsule core, is dissolved in the solvent of the oil phase. The addition method can be either heating and dissolving it together with other components of the oil phase, or dissolving it first in a solvent and then adding it to the oil phase according to the formulation ratio for emulsification.

[0063] The method for preparing the thermosensitive microcapsule dispersion of the present invention specifically includes the following steps: C1, oil phase preparation: heating the microcapsule core component containing organic solvent until completely dissolved; C2, aqueous phase preparation: dissolving the water-soluble protective colloid in water to prepare an aqueous solution with a mass concentration of 3-15%; C3, capsule dispersion preparation: adding the oil phase to the aqueous phase under high-speed emulsification conditions, emulsifying for 2-10 minutes, adding a curing agent, raising the temperature to 40-60℃, and reacting for 3-6 hours.

[0064] The hydrophobic thermoplastic resin of this invention is incorporated into the core portion of the microcapsule. This hydrophobic thermoplastic resin has a different polymer structure from the polyurethane in the capsule wall, possessing hydrophobic properties and a structure that does not readily form hydrogen bonds, thus hindering water vapor transport. Furthermore, it has a different internal crystallization aggregation mode compared to the polyurethane or polyurea in the capsule wall, complementing the polyurethane capsule wall and increasing the barrier to water vapor passage. This acts as another barrier against airborne moisture, contributing to improved moisture resistance. Simultaneously, the presence of this hydrophobic thermoplastic resin, as a supplement to the capsule wall, can appropriately reduce the capsule wall thickness, improving capsule stability and thus enhancing the thermal response of the thermosensitive film, thereby improving sensitivity. Therefore, the addition of the resin does not affect sensitivity while simultaneously providing a certain degree of water vapor barrier effect; thus, the addition of the resin of this invention simultaneously improves sensitivity and enhances water vapor barrier function.

[0065] The thermosensitive microcapsule dispersion of the present invention is applied to medical thermosensitive films. The manufacturing process is simple, the film has high sensitivity, and it has good storage stability and is not prone to blackening under high temperature and high humidity conditions.

[0066] (6) Fabrication of thermal recording layer

[0067] The thermal recording layer is prepared into a coating solution according to the above components, coated onto a transparent support, and then dried. The drying temperature should be below 40-95℃; too low a temperature results in slow drying, while too high a temperature can cause premature color development of the capsule. Coating methods include air knife coating, bar blade coating, strip coating, pure bar blade coating, short-dwelling coating, curtain coating, slit coating, and mold coating.

[0068] 2. Protective layer

[0069] The protective layer protects the heat-sensitive layer and its main components are adhesives and fillers.

[0070] (1) Adhesive

[0071] Examples of adhesives used as protective layers include: fully or partially saponified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol, carboxyl-modified polyvinyl alcohol, silicone-modified polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, alkali salts of styrene-maleic anhydride copolymers, alkali salts of ethylene-acrylic acid copolymers, and alkali salts of styrene-acrylic acid copolymers, as well as hydrophobic resins such as styrene-butadiene copolymers, acrylic copolymers, and polyurethane resins. When using hydrophobic resins as adhesives, they can be used in latex form.

[0072] (2) Fillers: The protective layer of this invention contains specific fillers, including inorganic pigments such as calcium carbonate, zinc stearate, calcium stearate, zinc oxide, aluminum oxide, stearamide, titanium dioxide, amorphous silica, colloidal silica, barium sulfate, and talc; organic pigments such as styrene resin particles, nylon resin particles, poly(meth)acrylate resin particles, and urea-formaldehyde resin particles; and lubricants such as alkyl phosphates, stearamide, zinc stearate, and calcium stearate. These fillers are all solid substances and require surface treatment and grinding before use to become hydrophilic dispersions.

[0073] (3) Other ingredients

[0074] Other components in the protective layer include boric acid, borax, dialdehyde starch, polyamide epichlorohydrin resin, crosslinking agents such as adipic acid dihydrazide, surfactants such as dialkyl sulfosuccinate, alkyl sulfonate, alkyl carboxylate, alkyl ethylene oxide, and fluorinated surfactants.

[0075] (4) Preparation of protective layer: The protective layer coating liquid is obtained by mixing and stirring. After the thermal recording layer is dried, the protective layer is coated on top of it. The coating liquid can be applied by air knife coating, bar knife coating, bar strip coating, pure bar knife coating, short residence coating, curtain coating, slit coating, mold coating, etc.

[0076] 3. Transparent Support: There are no particular limitations on the transparent support used for setting the thermal recording layer. However, in medical transparent thermal recording materials requiring high-energy printing, a heat-resistant polyethylene terephthalate film is preferred. Its thickness is approximately 20 to approximately 200 μm, and it can be colored blue. Furthermore, to improve adhesion to the thermal recording layer, a primer coating can be applied to the surface of the transparent support, or corona discharge treatment can be performed before applying the coating liquid for the thermal recording layer. Alternatively, a conductive agent can be used for conductive treatment. Additionally, to improve the mobility of the transparent thermal recording material, a back layer containing pigments such as resin particles and binders can be formed on the back of the support.

[0077] Compared with existing technologies, the present invention has a simple process, high thermal sensitivity, and does not cause the color to darken or turn black under high temperature and high humidity, thus exhibiting good resistance to damp heat. Attached Figure Description

[0078] Figure 1 This is a schematic diagram of a pattern printed on thermal film.

[0079] Figure 2 This is a summary table of thermal film test results. Detailed Implementation Example

[0080] Preparation steps of dye thermosensitive microcapsule dispersion 1:

[0081] Preparation of C1 oil phase: 10g of ODB-2 (Shandong Ruikang Essence Co., Ltd.), 5g of GN-2 (Tokyo Kasei Corporation, Japan), 18g of ethyl acetate, 0.5g of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole (Hangzhou Shangyou Chemical), 15g of isocyanate HMDI (Yantai Wanhua) and 2g of plastic resin B-44 were dissolved at 90℃ to obtain the oil phase.

[0082] C2 Aqueous Phase Preparation: 200g of 5% polyvinyl alcohol (PVA-224) and 25g of 7# surfactant (China Lucky Group) were mixed evenly to obtain the aqueous phase.

[0083] C3 Emulsification Reaction: The oil phase obtained above was slowly added to the aqueous phase of high-speed emulsification (ARM5 from Wuhan Yongxun Machinery Equipment Co., Ltd.). The emulsification speed was 8000 r / min and the emulsification time was 8 min. 150 g of water and 2 g of triethylenetetramine were added, and the mixture was stirred and reacted at 55 °C for 3 hours to obtain a thermosensitive dye microcapsule dispersion 1 with an average particle size of 0.64 μm.

[0084] Preparation steps of colorimetric reagent thermosensitive microcapsule dispersion 1:

[0085] Preparation of C1 oil phase: 33g of color developer 4,4′-dihydroxydiphenyl sulfone, 0.5g of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole (Hangzhou Shangyou Chemical), 18g of ethyl acetate, 15g of isocyanate HMDI (Yantai Wanhua) and 2g of plastic resin B-44 were dissolved by heating at 90℃ to obtain the oil phase.

[0086] C2 Aqueous Phase Preparation: 200g of 5% polyvinyl alcohol (PVA-224) and 25g of 7# surfactant (China Lucky Group Co., Ltd.) were mixed evenly to obtain the aqueous phase.

[0087] C3 Emulsification Reaction: The oil phase obtained above was slowly added to the aqueous phase of high-speed emulsification (ARM5 from Wuhan Yongxun Machinery Equipment Co., Ltd.). The emulsification speed was 8000 r / min and the emulsification time was 8 min. 150 g of water and 2 g of triethylenetetramine were added, and the mixture was stirred and reacted at 55 °C for 3 hours to obtain a thermosensitive colorimetric agent microcapsule dispersion 1 with an average particle size of 0.52 μm.

[0088] Thermosensitive layer formulation:

[0089] Thermosensitive dye microcapsule dispersion 1 35g

[0090] Thermosensitive colorimetric reagent microcapsule dispersion 1 35g

[0091] Carboxylated styrene-butadiene latex Shandong Xinzexiang Chemical 20g

[0092] Surfactant 1292, Jiangsu Haian Petrochemical, 1g

[0093] BYK-348 (Bik Chemical) 0.5g

[0094] 8.5g of deionized water

[0095] Protective layer formulation:

[0096] Acrylic emulsion LA6162, Foshan Xinguangli, 11.8g

[0097] Polyurethane resin latex AP-30F, Dai Nippon Ink & Chemical Industry, 5g

[0098] Acetylacetyl-modified polyvinyl alcohol Z-410, 8% aqueous solution, 32.5g, Nippon Synthetic Chemical Industry.

[0099] ADH (1%) Shanghai Shenzhi Chemical 13g

[0100] Stearamide (Shangnuotai, 25% solids content) 2.2g

[0101] 4% boric acid solution, Shandong Yihui Chemical Co., Ltd., 14g

[0102] Calcium stearate (25%) 5g

[0103] 1292 8% Jiangsu Haian Petrochemical 3.5g

[0104] Perfluorooctanoic acid 5% Hubei Yunmei Technology Co., Ltd. 2g

[0105] 11g of water Example

[0106] Preparation steps of dye thermosensitive microcapsule dispersion 2:

[0107] Preparation of C1 oil phase: 10g of ODB-2 (Shandong Ruikang Essence Co., Ltd.), 5g of GN-2 (Tokyo Kasei Corporation, Japan), 18g of ethyl acetate, 0.5g of 2,4-di(tert-butyl)-3-methylphenol, 15g of isocyanate HMDI (Yantai Wanhua), and 2g of plastic resin B48N were dissolved by heating at 90℃ to obtain the oil phase.

[0108] C2 Aqueous Phase Preparation: 200g of 5% polyvinyl alcohol (PVA-224) and 25g of 7# surfactant (China Lucky Group) were mixed evenly to obtain the aqueous phase.

[0109] C3 Emulsification Reaction: The oil phase obtained above was slowly added to the aqueous phase of high-speed emulsification (ARM5 from Wuhan Yongxun Machinery Equipment Co., Ltd.). The emulsification speed was 8000 r / min and the emulsification time was 8 min. 150 g of water and 2 g of triethylenetetramine were added, and the mixture was stirred and reacted at 45 °C for 8 hours to obtain a thermosensitive dye microcapsule dispersion 2 with an average particle size of 0.74 μm.

[0110] Preparation steps of colorimetric reagent thermosensitive microcapsule dispersion 2:

[0111] Preparation of C1 oil phase: 33g of color developer 4,4′-dihydroxydiphenyl sulfone, 18g of ethyl acetate, 15g of isocyanate HMDI (Yantai Wanhua), and 2g of plastic resin B48N were dissolved at 90℃ to obtain the oil phase.

[0112] C2 Aqueous Phase Preparation: 200g of 5% polyvinyl alcohol (PVA-224) and 25g of 7# surfactant (China Lucky Group Co., Ltd.) were mixed evenly to obtain the aqueous phase.

[0113] C3 Emulsification Reaction: The oil phase obtained above was slowly added to the aqueous phase of high-speed emulsification (ARM5 from Wuhan Yongxun Machinery Equipment Co., Ltd.). The emulsification speed was 8000 r / min and the emulsification time was 8 min. 150 g of water and 2 g of triethylenetetramine were added, and the mixture was stirred and reacted at 45 °C for 8 hours to obtain a thermosensitive colorimetric agent microcapsule dispersion 2 with an average particle size of 0.68 μm.

[0114] Thermosensitive layer formulation:

[0115] Thermosensitive dye microcapsule dispersion 2 35g

[0116] Thermosensitive colorimetric reagent microcapsule dispersion 2 35g

[0117] Carboxylated styrene-butadiene latex Shandong Xinzexiang Chemical 20g

[0118] Surfactant 1292, Jiangsu Haian Petrochemical, 1g

[0119] BYK-348 (Bik Chemical) 0.5g

[0120] 8.5g of deionized water

[0121] Protective layer formulation:

[0122] Acrylic emulsion LA6162, Foshan Xinguangli, 11.8g

[0123] Polyurethane resin latex AP-30F, Dai Nippon Ink & Chemical Industry, 5g

[0124] Acetylacetyl-modified polyvinyl alcohol Z-410, 8% aqueous solution, 32.5g, Nippon Synthetic Chemical Industry.

[0125] ADH (1%) Shanghai Shenzhi Chemical 13g

[0126] Calcium stearate (25%), Shanghai Better Chemical Co., Ltd., 7.2g

[0127] 4% boric acid solution, Shandong Yihui Chemical Co., Ltd., 14g

[0128] 1292 8% Jiangsu Haian Petrochemical 3.5g

[0129] Perfluorooctanoic acid 5% Hubei Yunmei Technology Co., Ltd. 2g

[0130] 11g of water Example

[0131] Preparation steps of dye thermosensitive microcapsule dispersion 3:

[0132] Preparation of C1 oil phase: 10g of ODB-2 (Shandong Ruikang Essence Co., Ltd.), 5g of GN-2 (Tokyo Kasei Corporation, Japan), 18g of ethyl acetate, 15g of isocyanate HMDI (Yantai Wanhua), 0.5g of antioxidant 264 (Changzhou Youfeng Chemical), and 1g of plastic resin F-2P were dissolved at 90℃ to obtain the oil phase.

[0133] C2 Aqueous Phase Preparation: 200g of 5% polyvinyl alcohol (PVA-224) and 25g of 7# surfactant (China Lucky Group) were mixed evenly to obtain the aqueous phase.

[0134] C3 Emulsification Reaction: The oil phase obtained above was slowly added to the aqueous phase of high-speed emulsification (ARM5 from Wuhan Yongxun Machinery Equipment Co., Ltd.). The emulsification speed was 8000 r / min and the emulsification time was 8 min. 150 g of water and 2 g of triethylenetetramine were added, and the mixture was stirred and reacted at 50 °C for 5 hours to obtain a thermosensitive dye microcapsule dispersion 3 with an average particle size of 0.59 μm.

[0135] This embodiment uses the existing technology of color developer grinding slurry.

[0136] Preparation steps for color developer grinding and dispersion 3:

[0137] Weigh out 33g of solid TGSH color developer, 100g of 5% polyvinyl alcohol (PVA-224) and 25g of 8% Lucky 7# surfactant, mix them evenly, and grind them in a bead mill until the color developer dispersion with an average particle size of 0.44μm (Wuhan Yongxun Machinery Equipment Co., Ltd. AMS10) is obtained.

[0138] Thermosensitive layer formulation:

[0139] Thermosensitive dye microcapsule dispersion 3 35g

[0140] Thermosensitive colorimetric reagent microcapsule dispersion 3 35g

[0141] Carboxylated styrene-butadiene latex Shandong Xinzexiang Chemical 20g

[0142] Surfactant 1292, Jiangsu Haian Petrochemical, 1g

[0143] BYK-348 (Bik Chemical) 0.5g

[0144] 8.5g of deionized water

[0145] Protective layer formulation:

[0146] Acrylic emulsion LA6162, Foshan Xinguangli, 16.8g

[0147] Polyurethane resin latex AP-30F, Dai Nippon Ink & Chemical Industry, 5g

[0148] Acetylacetyl-modified polyvinyl alcohol Z-410, 8% aqueous solution, 32.5g, Nippon Synthetic Chemical Industry.

[0149] ADH (1%) Shanghai Shenzhi Chemical 13g

[0150] 4% boric acid solution, Shandong Yihui Chemical Co., Ltd., 14g

[0151] 1292 8% Jiangsu Haian Petrochemical 3.5g

[0152] Calcium stearate (25%), Shanghai Better Chemical Co., Ltd., 7.2g

[0153] Perfluorooctanoic acid 5% Hubei Yunmei Technology Co., Ltd. 2g

[0154] 11g of water Example

[0155] Preparation steps of dye thermosensitive microcapsule dispersion 4:

[0156] Preparation of C1 oil phase: 10g of ODB-2 (Shandong Ruikang Essence Co., Ltd.), 5g of GN-2 (Tokyo Kasei Corporation, Japan), 18g of ethyl acetate (boiling point 126.5℃ at standard atmospheric pressure), 0.5g of antioxidant 264 (Changzhou Youfeng Chemical), 15g of isocyanate IPDI (Yantai Wanhua), and 2.6g of plastic resin ES220 were dissolved at 90℃ to obtain the oil phase.

[0157] C2 Aqueous Phase Preparation: 200g of 5% polyvinyl alcohol (PVA-224) and 25g of 7# surfactant (China Lucky Group) were mixed evenly to obtain the aqueous phase.

[0158] C3 Emulsification Reaction: The oil phase obtained above was slowly added to the aqueous phase of high-speed emulsification (ARM5 of Wuhan Yongxun Machinery Equipment Co., Ltd.). The emulsification speed was 8000 r / min and the emulsification time was 8 min. 150 g of water and 3 g of ethylene glycol were added, and the mixture was stirred and reacted at 55 °C for 5 hours to obtain a thermosensitive dye microcapsule dispersion 4 with an average particle size of 0.59 μm.

[0159] Preparation steps of colorimetric reagent thermosensitive microcapsule dispersion 4:

[0160] Preparation of C1 oil phase: 33g of color developer 4,4′-dihydroxydiphenyl sulfone, 18g of ethyl acetate, 15g of isocyanate IPDI (Yantai Wanhua), and 2.6g of plastic resin ES220 were dissolved at 90℃ to obtain the oil phase.

[0161] C2 Aqueous Phase Preparation: 200g of 5% polyvinyl alcohol (PVA-224) and 25g of 7# surfactant (China Lucky Group) were mixed evenly to obtain the aqueous phase.

[0162] C3 Emulsification Reaction: The oil phase obtained above was slowly added to the aqueous phase of high-speed emulsification (ARM5 of Wuhan Yongxun Machinery Equipment Co., Ltd.). The emulsification speed was 8000 r / min and the emulsification time was 8 min. 150 g of water and 2 g of triethylenetetramine were added, and the mixture was stirred and reacted at 50 °C for 5 hours to obtain a thermosensitive colorimetric agent microcapsule dispersion 4 with an average particle size of 0.99 μm.

[0163] Thermosensitive layer formulation:

[0164] Thermosensitive dye microcapsule dispersion 4 35g

[0165] Thermosensitive colorimetric reagent microcapsule dispersion 4 35g

[0166] Carboxylated styrene-butadiene latex Shandong Xinzexiang Chemical 20g

[0167] Surfactant 1292, Jiangsu Haian Petrochemical, 1g

[0168] BYK-348 (Bik Chemical) 0.5g

[0169] 8.5g of deionized water

[0170] Protective layer formulation:

[0171] Acrylic emulsion LA6162, Foshan Xinguangli, 16.8g

[0172] Polyurethane resin latex AP-30F, Dai Nippon Ink & Chemical Industry, 5g

[0173] Acetylacetyl-modified polyvinyl alcohol Z-410, 8% aqueous solution, 32.5g, Nippon Synthetic Chemical Industry.

[0174] ADH (1%) Shanghai Shenzhi Chemical 13g

[0175] Stearamide (Shangnuotai, 25% solids content) 2.2g

[0176] 4% boric acid solution, Shandong Yihui Chemical Co., Ltd., 14g

[0177] Calcium stearate (25%) Shanghai Better Chemical 5g

[0178] 1292 8% Jiangsu Haian Petrochemical 3.5g

[0179] Perfluorooctanoic acid 5% Hubei Yunmei Technology Co., Ltd. 2g

[0180] 11g of water Example

[0181] Preparation steps of dye thermosensitive microcapsule dispersion 5:

[0182] Preparation of C1 oil phase: 10g of S-205 (Kangai Technology Penglai Chemical Co., Ltd.), 5g of GN-2 (Tokyo Kasei Corporation, Japan), 18g of ethyl acetate, 15g of isocyanate HMDI (Yantai Wanhua), 0.5g of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole (Hangzhou Shangyou Chemical), and 2g of plastic resin DX526P were dissolved at 90℃ to obtain the oil phase.

[0183] C2 aqueous phase preparation: 200g of 6% polyvinyl alcohol (PVA-217) and 25g of 7# surfactant (China Lucky Group) were mixed evenly to obtain the aqueous phase.

[0184] C3 Emulsification Reaction: The oil phase obtained above was slowly added to the aqueous phase of high-speed emulsification (ARM5 from Wuhan Yongxun Machinery Equipment Co., Ltd.). The emulsification speed was 8000 r / min and the emulsification time was 2 min. 150 g of water and 2 g of triethylenetetramine were added, and the mixture was stirred and reacted at 55 °C for 3 hours to obtain a thermosensitive dye microcapsule dispersion 5 with an average particle size of 0.82 μm.

[0185] Preparation steps of colorimetric reagent thermosensitive microcapsule dispersion 5:

[0186] Preparation of C1 oil phase: 33g of color developer 4,4′-dihydroxydiphenyl sulfone, 18g of ethyl acetate, 15g of isocyanate HMDI (Yantai Wanhua), and 2g of plastic resin DX526P were dissolved at 90℃ to obtain the oil phase.

[0187] C2 aqueous phase preparation: 200g of 6% polyvinyl alcohol (PVA-217) and 25g of 7# surfactant (China Lucky Group) were mixed evenly to obtain the aqueous phase.

[0188] C3 Emulsification Reaction: The oil phase obtained above was slowly added to the aqueous phase of high-speed emulsification (ARM5 from Wuhan Yongxun Machinery Equipment Co., Ltd.). The emulsification speed was 8000 r / min and the emulsification time was 5 min. 150 g of water and 2 g of triethylenetetramine were added, and the mixture was stirred and reacted at 50 °C for 3 hours to obtain a thermosensitive colorimetric agent microcapsule dispersion 5 with an average particle size of 0.68 μm.

[0189] Thermosensitive layer formulation:

[0190] Thermosensitive dye microcapsule dispersion 5 35g

[0191] Thermosensitive colorimetric reagent microcapsule dispersion 5 35g

[0192] Carboxylated styrene-butadiene latex Shandong Xinzexiang Chemical 20g

[0193] Surfactant 1292, Jiangsu Haian Petrochemical, 1g

[0194] BYK-348 (Bik Chemical) 0.5g

[0195] 8.5g of deionized water

[0196] Protective layer formulation:

[0197] Acrylic emulsion LA6162, Foshan Xinguangli, 16.8g

[0198] Polyurethane resin latex AP-30F, Dai Nippon Ink & Chemical Industry, 5g

[0199] Acetylacetyl-modified polyvinyl alcohol Z-410, 8% aqueous solution, 32.5g, Nippon Synthetic Chemical Industry.

[0200] ADH (1%) Shanghai Shenzhi Chemical 13g

[0201] Calcium stearate (25%), Shanghai Better Chemical Co., Ltd., 7.2g

[0202] 4% boric acid solution, Shandong Yihui Chemical Co., Ltd., 14g

[0203] 1292 8% Jiangsu Haian Petrochemical 3.5g

[0204] Perfluorooctanoic acid 5% Hubei Yunmei Technology Co., Ltd. 2g

[0205] 11g of water Example

[0206] 6 steps for thermosensitive dye microcapsule dispersion:

[0207] Preparation of C1 oil phase: 10g of S-205 (Kangai Technology Penglai Chemical Co., Ltd.), 5g of GN-2 (Tokyo Kasei Corporation, Japan), 0.5g of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole (Hangzhou Shangyou Chemical), 18g of ethyl acetate, 15g of isocyanate IPDI (Yantai Wanhua), 1g of plastic resin DX526P, and 1g of plastic resin 120 were dissolved by heating at 90℃ to obtain the oil phase.

[0208] C2 aqueous phase preparation: 200g of 6% polyvinyl alcohol (PVA-217) and 25g of 7# surfactant (China Lucky Group) were mixed evenly to obtain the aqueous phase.

[0209] C3 Emulsification Reaction: The oil phase obtained above was slowly added to the aqueous phase of high-speed emulsification (ARM5 of Wuhan Yongxun Machinery Equipment Co., Ltd.). The emulsification speed was 8000 r / min and the emulsification time was 8 min. 150 g of water and 2 g of triethylenetetramine were added, and the mixture was stirred and reacted at 55 °C for 3 hours to obtain a thermosensitive dye microcapsule dispersion 6 with an average particle size of 0.87 μm.

[0210] Thermosensitive layer formulation:

[0211] Thermosensitive dye microcapsule dispersion 6 35g

[0212] Colorimetric reagent dispersion 3 39g

[0213] Carboxylated styrene-butadiene latex Shandong Xinzexiang Chemical 20g

[0214] Surfactant 1292, Jiangsu Haian Petrochemical, 1g

[0215] BYK-348 (Bik Chemical) 0.5g

[0216] 8.5g of deionized water

[0217] Protective layer formulation:

[0218] Acrylic emulsion LA6162, Foshan Xinguangli, 16.8g

[0219] Polyurethane resin latex AP-30F, Dai Nippon Ink & Chemical Industry, 5g

[0220] Acetylacetyl-modified polyvinyl alcohol Z-410, 8% aqueous solution, 32.5g, Nippon Synthetic Chemical Industry.

[0221] ADH (1%) Shanghai Shenzhi Chemical 13g

[0222] Calcium stearate (25%), Shanghai Better Chemical Co., Ltd., 7.2g

[0223] 4% boric acid solution, Shandong Yihui Chemical Co., Ltd., 14g

[0224] 1292 8% Jiangsu Haian Petrochemical 3.5g

[0225] Perfluorooctanoic acid 5% Hubei Yunmei Technology Co., Ltd. 2g

[0226] 11g of water Example

[0227] Thermosensitive layer formulation:

[0228] Thermosensitive dye microcapsule dispersion 2 15g

[0229] Thermosensitive dye microcapsule dispersion 6 20g

[0230] Colorimetric reagent dispersion 3 39g

[0231] Carboxylated styrene-butadiene latex Shandong Xinzexiang Chemical 20g

[0232] Surfactant 1292, Jiangsu Haian Petrochemical, 1g

[0233] BYK-348 (Bik Chemical) 0.5g

[0234] 8.5g of deionized water

[0235] Protective layer formulation:

[0236] Acrylic emulsion LA6162, Foshan Xinguangli, 16.8g

[0237] Polyurethane resin latex AP-30F, Dai Nippon Ink & Chemical Industry, 5g

[0238] Acetylacetyl-modified polyvinyl alcohol Z-410, 8% aqueous solution, 32.5g, Nippon Synthetic Chemical Industry.

[0239] ADH (1%) Shanghai Shenzhi Chemical 13g

[0240] Zinc stearate (25%), Shanghai Better Chemical Co., Ltd., 7.2g

[0241] 4% boric acid solution, Shandong Yihui Chemical Co., Ltd., 14g

[0242] 1292 8% Jiangsu Haian Petrochemical 3.5g

[0243] Perfluorooctanoic acid 5% Hubei Yunmei Technology Co., Ltd. 2g

[0244] 11g of water

[0245] Comparative Example 1

[0246] Comparison of the preparation steps of dye thermosensitive microcapsule dispersion:

[0247] Preparation of C1 oil phase: 10g of ODB-2 (Shandong Ruikang Essence Co., Ltd.), 5g of GN-2 (Tokyo Kasei Corporation, Japan), 0.5g of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole (Hangzhou Shangyou Chemical), 18g of ethyl acetate, and 15g of IPDI isocyanate (Yantai Wanhua) were dissolved at 90℃ to obtain the oil phase.

[0248] C2 Aqueous Phase Preparation: 200g of 5% polyvinyl alcohol (PVA-224) and 25g of 7# surfactant (China Lucky Group) were mixed evenly to obtain the aqueous phase.

[0249] C3 Emulsification Reaction: The oil phase obtained above was slowly added to the aqueous phase of high-speed emulsification (ARM5 from Wuhan Yongxun Machinery Equipment Co., Ltd.). The emulsification speed was 8000 r / min and the emulsification time was 8 min. 150 g of water and 2 g of triethylenetetramine were added, and the mixture was stirred and reacted at 50 °C for 5 hours to obtain a Comparative 1 thermosensitive dye microcapsule dispersion with an average particle size of 0.88 μm.

[0250] Comparison 1: Preparation steps of the colorimetric reagent thermosensitive microcapsule dispersion:

[0251] Preparation of C1 oil phase: 33g of color developer 4,4′-dihydroxydiphenyl sulfone, 18g of ethyl acetate and 15g of isocyanate IPDI (Yantai Wanhua) were dissolved by heating at 90℃ to obtain the oil phase.

[0252] C2 Aqueous Phase Preparation: 200g of 5% polyvinyl alcohol (PVA-224) and 25g of 7# surfactant (China Lucky Group) were mixed evenly to obtain the aqueous phase.

[0253] C3 Emulsification Reaction: The oil phase obtained above was slowly added to the aqueous phase of high-speed emulsification (ARM5 of Wuhan Yongxun Machinery Equipment Co., Ltd.). The emulsification speed was 8000 r / min and the emulsification time was 5 min. 150 g of water and 2 g of triethylenetetramine were added, and the mixture was stirred and reacted at 55 °C for 3 hours to obtain the Comparative 1 thermosensitive colorimetric agent microcapsule dispersion with an average particle size of 0.64 μm.

[0254] Thermosensitive layer formulation:

[0255] Comparison 1: Thermosensitive dye microcapsule dispersion 35g

[0256] Comparison 1: Thermosensitive colorimetric reagent microcapsule dispersion 35g

[0257] Carboxylated styrene-butadiene latex Shandong Xinzexiang Chemical 20g

[0258] Surfactant 1292, Jiangsu Haian Petrochemical, 1g

[0259] BYK-348 (Bik Chemical) 0.5g

[0260] 8.5g of deionized water

[0261] Protective layer formulation:

[0262] Acrylic emulsion LA6162, Foshan Xinguangli, 16.8g

[0263] Polyurethane resin latex AP-30F, Dai Nippon Ink & Chemical Industry, 5g

[0264] Acetylacetyl-modified polyvinyl alcohol Z-410, 8% aqueous solution, 32.5g, Nippon Synthetic Chemical Industry.

[0265] ADH (1%) Shanghai Shenzhi Chemical 13g

[0266] Zinc stearate (25%), Shanghai Better Chemical Co., Ltd., 7.2g

[0267] 4% boric acid solution, Shandong Yihui Chemical Co., Ltd., 14g

[0268] 1292 8% Jiangsu Haian Petrochemical 3.5g

[0269] Perfluorooctanoic acid 5% Hubei Yunmei Technology Co., Ltd. 2g

[0270] 11g of water

[0271] Comparative Example 2

[0272] Comparison of the preparation steps of dye thermosensitive microcapsule dispersions:

[0273] Preparation of C1 oil phase: 10g of ODB-2 (Shandong Ruikang Essence Co., Ltd.), 5g of GN-2 (Tokyo Kasei Corporation, Japan), 0.5g of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole (Hangzhou Shangyou Chemical), 18g of ethyl acetate, 15g of isocyanate IPDI (Yantai Wanhua) and 2.6g of plastic resin ES220 were dissolved by heating at 90℃ to obtain the oil phase.

[0274] C2 Aqueous Phase Preparation: 200g of 5% polyvinyl alcohol (PVA-224) and 25g of 7# surfactant (China Lucky Group) were mixed evenly to obtain the aqueous phase.

[0275] C3 Emulsification Reaction: The oil phase obtained above was slowly added to the aqueous phase of high-speed emulsification (ARM5 from Wuhan Yongxun Machinery Equipment Co., Ltd.). The emulsification speed was 8000 r / min and the emulsification time was 8 min. 150 g of water and 2 g of triethylenetetramine were added, and the mixture was stirred and reacted at 55 °C for 3 hours to obtain a dispersion of thermosensitive dye microcapsules with an average particle size of 0.98 μm.

[0276] Comparison of the preparation steps of the colorimetric reagent thermosensitive microcapsule dispersion:

[0277] Preparation of C1 oil phase: 33g of color developer 4,4′-dihydroxydiphenyl sulfone, 18g of ethyl acetate, 15g of isocyanate IPDI (Yantai Wanhua), and 2.6g of plastic resin ES220 were dissolved at 90℃ to obtain the oil phase.

[0278] C2 Aqueous Phase Preparation: 200g of 5% polyvinyl alcohol (PVA-224) and 25g of 7# surfactant (China Lucky Group Co., Ltd.) were mixed evenly to obtain the aqueous phase.

[0279] C3 Emulsification Reaction: The oil phase obtained above was slowly added to the aqueous phase of high-speed emulsification (ARM5 from Wuhan Yongxun Machinery Equipment Co., Ltd.). The emulsification speed was 8000 r / min and the emulsification time was 8 min. 150 g of water and 2 g of triethylenetetramine were added, and the mixture was stirred and reacted at 55 °C for 3 hours. 150 g of water and 6.2 g of glycerol were added, and the mixture was stirred and reacted at 55 °C for 3 hours to obtain a microcapsule dispersion of the thermosensitive colorimetric reagent with an average particle size of 0.64 μm.

[0280] Thermosensitive layer formulation:

[0281] Comparison 2: Thermosensitive dye microcapsule dispersion 35g

[0282] Comparison 2: Thermosensitive colorimetric reagent microcapsule dispersion 35g

[0283] Carboxylated styrene-butadiene latex Shandong Xinzexiang Chemical 20g

[0284] Surfactant 1292, Jiangsu Haian Petrochemical, 1g

[0285] BYK-348 (Bik Chemical) 0.5g

[0286] 8.5g of deionized water

[0287] Protective layer formulation:

[0288] Acrylic emulsion LA6162, Foshan Xinguangli, 16.8g

[0289] Polyurethane resin latex AP-30F, Dai Nippon Ink & Chemical Industry, 5g

[0290] Acetylacetyl-modified polyvinyl alcohol Z-410, 8% aqueous solution, 32.5g, Nippon Synthetic Chemical Industry.

[0291] ADH (1%) Shanghai Shenzhi Chemical 13g

[0292] Zinc stearate (25%), Shanghai Better Chemical Co., Ltd., 7.2g

[0293] 4% boric acid solution, Shandong Yihui Chemical Co., Ltd., 14g

[0294] 1292 8% Jiangsu Haian Petrochemical 3.5g

[0295] Perfluorooctanoic acid 5% Hubei Yunmei Technology Co., Ltd. 2g

[0296] 11g of water

[0297] Comparative Example 3

[0298] Comparison of the preparation steps of the thermosensitive microcapsule dispersion of 3 dyes:

[0299] Preparation of C1 oil phase: 10g of ODB-2 (Shandong Ruikang Essence Co., Ltd.), 5g of GN-2 (Tokyo Kasei Corporation, Japan), 18g of ethyl acetate, 0.5g of antioxidant 264 (Changzhou Youfeng Chemical), 15g of isocyanate IPDI (Yantai Wanhua), and 0.5g of plastic resin F-2P were dissolved at 90℃ to obtain the oil phase.

[0300] C2 Aqueous Phase Preparation: 200g of 5% polyvinyl alcohol (PVA-224) and 25g of 7# surfactant (China Lucky Group) were mixed evenly to obtain the aqueous phase.

[0301] C3 Emulsification Reaction: The oil phase obtained above was slowly added to the aqueous phase of high-speed emulsification (ARM5 from Wuhan Yongxun Machinery Equipment Co., Ltd.). The emulsification speed was 8000 r / min and the emulsification time was 8 min. 150 g of water and 2 g of triethylenetetramine were added, and the mixture was stirred and reacted at 55 °C for 3 hours to obtain a dispersion of Comparative 3 thermosensitive dye microcapsules with an average particle size of 0.34 μm.

[0302] Comparison of the preparation steps of the thermosensitive microcapsule dispersion of the 3 colorimetric reagents:

[0303] Preparation of C1 oil phase: 33g of color developer 4,4′-dihydroxydiphenyl sulfone, 18g of ethyl acetate, 15g of isocyanate IPDI (Yantai Wanhua), and 0.5g of plastic resin F-2P were dissolved at 90℃ to obtain the oil phase.

[0304] C2 Aqueous Phase Preparation: 200g of 5% polyvinyl alcohol (PVA-224) and 25g of 7# surfactant (China Lucky Group) were mixed evenly to obtain the aqueous phase.

[0305] C3 Emulsification Reaction: The oil phase obtained above was slowly added to the aqueous phase of high-speed emulsification (ARM5 of Wuhan Yongxun Machinery Equipment Co., Ltd.). The emulsification speed was 8000 r / min and the emulsification time was 8 min. 150 g of water and 2 g of triethylenetetramine were added, and the mixture was stirred and reacted at 55 °C for 3 hours to obtain the thermosensitive colorimetric agent microcapsule dispersion of Comparative Example 3 with an average particle size of 0.44 μm.

[0306] Thermosensitive layer formulation:

[0307] Comparison of 3 thermosensitive dye microcapsule dispersions (35g)

[0308] Comparison of 35g thermosensitive colorimetric reagent microcapsule dispersion

[0309] Carboxylated styrene-butadiene latex Shandong Xinzexiang Chemical 20g

[0310] Surfactant 1292, Jiangsu Haian Petrochemical, 1g

[0311] BYK-348 (Bik Chemical) 0.5g

[0312] 8.5g of deionized water

[0313] Protective layer formulation:

[0314] Acrylic emulsion LA6162, Foshan Xinguangli, 16.8g

[0315] Polyurethane resin latex AP-30F, Dai Nippon Ink & Chemical Industry, 5g

[0316] Acetylacetyl-modified polyvinyl alcohol Z-410, 8% aqueous solution, 32.5g, Nippon Synthetic Chemical Industry.

[0317] ADH (1%) Shanghai Shenzhi Chemical 13g

[0318] Zinc stearate (25%), Shanghai Better Chemical Co., Ltd., 7.2g

[0319] 4% boric acid solution, Shandong Yihui Chemical Co., Ltd., 14g

[0320] 1292 8% Jiangsu Haian Petrochemical 3.5g

[0321] Perfluorooctanoic acid 5% Hubei Yunmei Technology Co., Ltd. 2g

[0322] 11g of water

[0323] Preparation of thermal film:

[0324] Comparative Example 4

[0325] Comparison of the preparation steps of 4 dye thermosensitive microcapsule dispersions:

[0326] Preparation of C1 oil phase: 10g of ODB-2 (Shandong Ruikang Essence Co., Ltd.), 5g of GN-2 (Tokyo Kasei Corporation, Japan), 18g of ethyl acetate, 0.5g of antioxidant 264 (Changzhou Youfeng Chemical), 15g of isocyanate IPDI (Yantai Wanhua), and 2g of plastic resin 803 MNS were dissolved by heating at 90℃ to obtain the oil phase.

[0327] C2 Aqueous Phase Preparation: 200g of 5% polyvinyl alcohol (PVA-224) and 25g of 7# surfactant (China Lucky Group Co., Ltd.) were mixed evenly to obtain the aqueous phase.

[0328] C3 Emulsification Reaction: The oil phase obtained above was slowly added to the aqueous phase of high-speed emulsification (ARM5 from Wuhan Yongxun Machinery Equipment Co., Ltd.). The emulsification speed was 8000 r / min and the emulsification time was 8 min. 150 g of water and 2 g of triethylenetetramine were added, and the mixture was stirred and reacted at 55 °C for 3 hours to obtain a Comparative 4 thermosensitive dye microcapsule dispersion with an average particle size of 0.9 μm.

[0329] Thermosensitive layer formulation:

[0330] Comparative Example 4: Thermosensitive Dye Microcapsule Dispersion 35g

[0331] Colorimetric reagent dispersion 3 35g

[0332] Carboxylated styrene-butadiene latex Shandong Xinzexiang Chemical 20g

[0333] Surfactant 1292, Jiangsu Haian Petrochemical, 1g

[0334] BYK-348 (Bik Chemical) 0.5g

[0335] 8.5g of deionized water

[0336] Protective layer formulation:

[0337] Acrylic emulsion LA6162, Foshan Xinguangli, 16.8g

[0338] Polyurethane resin latex AP-30F, Dai Nippon Ink & Chemical Industry, 5g

[0339] Acetylacetyl-modified polyvinyl alcohol Z-410, 8% aqueous solution, 32.5g, Nippon Synthetic Chemical Industry.

[0340] ADH (1%) Shanghai Shenzhi Chemical 13g

[0341] Zinc stearate (25%), Shanghai Better Chemical Co., Ltd., 7.2g

[0342] 4% boric acid solution, Shandong Yihui Chemical Co., Ltd., 14g

[0343] 1292 8% Jiangsu Haian Petrochemical 3.5g

[0344] Perfluorooctanoic acid 5% Hubei Yunmei Technology Co., Ltd. 2g

[0345] 11g of water

[0346] Comparative Example 5

[0347] Comparison of the preparation steps of 5 dye thermosensitive microcapsule dispersions:

[0348] Preparation of C1 oil phase: 10g of ODB-2 (Shandong Ruikang Essence Co., Ltd.), 5g of GN-2 (Tokyo Kasei Corporation, Japan), 18g of ethyl acetate (boiling point of 126.5℃ at standard atmospheric pressure), 0.5g of antioxidant 264 (Changzhou Youfeng Chemical), 15g of isocyanate IPDI (Yantai Wanhua), and 2g of plastic resin ES330 were dissolved by heating at 90℃ to obtain the oil phase.

[0349] C2 Aqueous Phase Preparation: 200g of 5% polyvinyl alcohol (PVA-224) and 25g of 7# surfactant (China Lucky Group) were mixed evenly to obtain the aqueous phase.

[0350] C3 Emulsification Reaction: The oil phase obtained above was slowly added to the aqueous phase of high-speed emulsification (ARM5 from Wuhan Yongxun Machinery Equipment Co., Ltd.). The emulsification speed was 8000 r / min and the emulsification time was 8 min. 150 g of water and 2 g of triethylenetetramine were added, and the mixture was stirred and reacted at 55 °C for 3 hours to obtain a Comparative 5 thermosensitive dye microcapsule dispersion with an average particle size of 0.9 μm.

[0351] Thermosensitive layer formulation:

[0352] Comparison of 5 thermosensitive dye microcapsule dispersions (35g)

[0353] Colorimetric reagent dispersion 3 35g

[0354] Carboxylated styrene-butadiene latex Shandong Xinzexiang Chemical 20g

[0355] Surfactant 1292, Jiangsu Haian Petrochemical, 1g

[0356] BYK-348 (Bik Chemical) 0.5g

[0357] 8.5g of deionized water

[0358] Protective layer formulation:

[0359] Acrylic emulsion LA6162, Foshan Xinguangli, 16.8g

[0360] Polyurethane resin latex AP-30F, Dai Nippon Ink & Chemical Industry, 5g

[0361] Acetylacetyl-modified polyvinyl alcohol Z-410, 8% aqueous solution, 32.5g, Nippon Synthetic Chemical Industry.

[0362] ADH (1%) Shanghai Shenzhi Chemical 13g

[0363] Zinc stearate (25%), Shanghai Better Chemical Co., Ltd., 7.2g

[0364] 4% boric acid solution, Shandong Yihui Chemical Co., Ltd., 14g

[0365] 1292 8% Jiangsu Haian Petrochemical 3.5g

[0366] Perfluorooctanoic acid 5% Hubei Yunmei Technology Co., Ltd. 2g

[0367] 11g of water

[0368] Preparation of thermal film:

[0369] The substrate is a transparent polyethylene terephthalate film colored blue, with a thickness of 175μm, produced by Lucky Huaguang Printing Technology Co., Ltd. In order to prevent static electricity, prevent sticking and improve adhesion and other properties, it is preferred to pre-coat the substrate with a base layer and a back layer. There are no special restrictions on the base layer and the back layer, as long as they meet the performance requirements of the film.

[0370] The aforementioned thermal layer was coated using a wire rod coater and dried at 60°C for 10 minutes, resulting in a coating weight of 10 g / m². After drying, the aforementioned protective layer was coated on top using a wire rod coater and dried at 60°C for 10 minutes, resulting in a coating weight of 3.5 g / m². This yielded the medical thermal films for testing in the embodiments and comparative examples of the present invention.

[0371] Testing methods for thermal films:

[0372] 1. TG Detection: Using a differential scanning calorimeter (DSC), approximately 5.0 mg of the sample was heated from 30°C to 200°C at a rate of 10°C / min under a nitrogen atmosphere, and held at this temperature for 10 minutes. It was then cooled to 30°C at a rate of 10°C / min, held at this temperature for 5 minutes, and then heated to 200°C at a rate of 10°C / min. The endothermic peak observed during this second heating was taken as the melting peak, and the temperature at which the melting peak appeared was taken as the melting point. If the melting peak was multimodal, the temperature at which the highest melting peak appeared was taken as the TG value.

[0373] 2. Artificial Accelerated Aging Method: The samples were placed in a dark room for artificial accelerated aging experiments. The experimental conditions were: temperature 50℃, humidity (60±5)%, aging time 14 days, and after aging, the samples were equilibrated again for 2 hours before the following tests were performed. Each sample needed to be equilibrated for 2 hours at a temperature of (23±2)℃ and a relative humidity of (50±5)% before processing.

[0374] 3. After printing with a Fuji 5100 thermal printer, the printed pattern is as shown in the attached image. Figure 1 The attached materials were tested using an Escherich 341C densitometer. Figure 1 Density values ​​at positions 1#, 2#, 3#, and 4#. Each test sample includes sample A (without accelerated aging) and sample B (after accelerated aging). Test results are as follows: Figure 2 As shown.

[0375] Test results show that the addition of the plastic resin TG in this invention within the temperature range of 40-70℃ results in small density changes in the film before and after humidification, and good resistance to damp heat.

Claims

1. A production method of a high-sensitivity moisture-resistant heat-sensitive microcapsule dispersion liquid, the heat-sensitive microcapsule dispersion liquid including a leuco dye microcapsule dispersion liquid and a color developer microcapsule dispersion liquid, characterized by, The preparation method comprises the following steps: C1, oil phase preparation: heating the colorless dye microcapsule core component and color developer microcapsule core component to complete dissolution with the capsule wall raw material polyisocyanate; C2, water phase preparation: mixing the 5% polyvinyl alcohol aqueous solution and surfactant to obtain the water phase; C3, microcapsule dispersion liquid preparation: adding the oil phase into the water phase under high-speed emulsification conditions, respectively emulsifying for 2-10 minutes, adding the capsule wall raw material polyol or polyamine, heating to 40-60℃, and reacting for 3-6 hours; The colorless dye microcapsule core component comprises colorless dye, ultraviolet absorber, hydrophobic thermoplastic resin and solvent, and the mass of the hydrophobic thermoplastic resin is 5-15% of the mass of the polyisocyanate; The color developer microcapsule core component comprises color developer, hydrophobic thermoplastic resin and solvent, and the mass of the hydrophobic thermoplastic resin is 5-15% of the mass of the polyisocyanate; The hydrophobic thermoplastic resin is one or more of the following: homopolymer or copolymer of olefin or chlorinated olefin, homopolymer or copolymer of acrylic acid and its ester or methacrylic acid and its ester, copolymer of olefin or chlorinated olefin and acrylic acid and its ester or methacrylic acid and its ester, and linear saturated polyester resin, and the TG is in the range of 40-70℃.

2. The production method of the high-sensitivity moisture-resistant heat-sensitive microcapsule dispersion liquid according to claim 1, characterized by: The microcapsule particle size is 0.4-1.0 μm.

3. A heat-sensitive sheet of heat-sensitive microcapsule dispersion, characterized by, The transparent support, the heat-sensitive recording layer comprising the colorless dye microcapsule dispersion liquid and the color developer microcapsule dispersion liquid or the color developer grinding dispersion liquid formed on the transparent support, and the protective layer comprising the filler and the adhesive formed on the heat-sensitive recording layer are prepared by the method of any one of claims 1-2.

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