Thermosensitive recording body

Abstract

Disclosed is a heat-sensitive recording body which has, in order on a support, a primer layer containing hollow particles, a binder, and inorganic pigment I, and a heat-sensitive recording layer containing a leuco dye, a color developer, and inorganic pigment II, and which is characterized by containing, as the color developer, an N,N'-diaryl urea-based compound represented by the following formula (1) (in the formula, R2 represents an alkyl group having 1 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and the aralkyl group and the aryl group are each optionally substituted with an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, or a halogen atom, and each R2 can be the same as or different from the others, A1 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and each A1 can be the same as or different from the others), and, as the inorganic pigment II, a pigment having an oil absorption of 130 ml / 100 g or less,

Description

Technical Field

[0001] This invention relates to a thermal recording device. Background Technology

[0002] Widely used thermal recorders record color images by utilizing a heat-induced colorimetric reaction between colorless or light-colored leuco dyes and phenols or organic acids. The advantages of such thermal recorders are, for example, that color images can be formed simply by applying heat, and furthermore, that the recording devices used for them can be compact, easily maintained, and generate less noise. For this reason, thermal recorders have been used in a wide range of technical fields as information recording materials in printing devices such as label printers, automatic ticket machines, CD / ATMs, order output devices used in restaurants, and data output devices in equipment used for scientific research.

[0003] Because this color development reaction is reversible, it is known that color images fade over time. This fading reaction is accelerated in high-temperature and high-humidity environments and further accelerated by contact with oils, plasticizers, etc., and the color may fade to the point that the recorded image becomes unrecognizable. In recent years, the use of alcohol for sterilization and disinfection has become a common practice in daily life, especially for the prevention of infectious diseases. Therefore, there is an increasing demand for improved performance of thermal recorders, for example, those that do not develop color in blank areas and do not fade in printed areas even when they come into contact with alcohol.

[0004] For example, Patent Document (PTL) 1 proposes a thermal recorder containing a diarylurea derivative as a colorimetric agent. However, the thermal recorder described in Patent Document 1 is inadequate in terms of alcohol resistance, plasticizer resistance, and water plasticizer resistance, and there is room for improvement.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: WO 2019 / 044462 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] The main objective of this invention is to provide a thermal recorder with excellent resistance to alcohol, plasticizers, and water plasticizers.

[0010] Solution for solving the problem

[0011] The inventors, considering the aforementioned problems in the prior art, conducted in-depth research. As a result, the inventors discovered a method for solving this problem. More specifically, the present invention provides the following thermal recording medium.

[0012] Project 1

[0013] A thermal recorder comprises, in sequence, a base coating layer and a thermal recording layer on a support.

[0014] The base coat consists of hollow particles, a binder, and inorganic pigment I.

[0015] The thermal recording layer contains leuco dyes, developer, and inorganic pigment II, and

[0016] The thermal recording layer contains an N,N'-diarylurea compound represented by formula (1) as a color developer, and an inorganic pigment II with an oil absorption of less than 130 ml / 100 g.

[0017]

[0018] R2 can be the same or different, and each represents C. 1-12 Alkyl, C 7-12 Aryl or C 6-12 Aryl, and aralkyl and aryl can each be C 1-12 Alkyl, C 1-12 Alkoxy, C 6-12 Aryl or halogen substitution; A1 can be the same or different, and each represents hydrogen or C. 1-4 alkyl.

[0019] Project 2

[0020] According to the thermal recorder described in Project 1, the content of inorganic pigment I is less than 60% by mass based on the total solid content of the base coating.

[0021] Project 3

[0022] According to the thermal recorder described in Project 1 or Project 2, the oil absorption of inorganic pigment I is less than 130 ml / 100 g.

[0023] Project 4

[0024] The thermal recorder according to any one of items 1 to 3, wherein the inorganic pigment II is at least one selected from the group consisting of calcium carbonate, aluminum hydroxide and clay.

[0025] Project 5

[0026] According to any one of Projects 1 to 4, the thermal recorder has a maximum particle size (D100) of 10 to 40 μm, an average particle size (D50) of 4.0 to 15 μm, a ratio of the maximum particle size (D100) to the average particle size (D50), i.e., D100 / D50, of 1.8 to 3.0, and the volume percentage of particles with a particle size of 2.0 μm or less is 1% or less.

[0027] Project 6

[0028] The thermal recorder according to any one of items 1 to 5, wherein the hollow particle has a hollowness of 80% to 98%.

[0029] Project 7

[0030] The thermal recorder according to any one of items 1 to 6, wherein the undercoat comprises an adhesive having a glass transition temperature of -10°C or less.

[0031] Project 8

[0032] The thermal recorder according to any one of items 1 to 7, wherein the thermal recording layer further comprises, as a second colorimetric agent, at least one selected from the group consisting of a urea-carbamate compound represented by formula (2), a cross-linked diphenyl sulfone compound represented by formula (3), and 4,4'-bis(3-tolylureo)diphenylmethane.

[0033]

[0034] Where n represents an integer from 1 to 6.

[0035] Project 9

[0036] According to the thermal recorder described in Project 8, the content of the second colorimetric agent is 0.2 to 3 parts by mass relative to 1 part by mass of leuco dye.

[0037] Project 10

[0038] According to any one of items 1 to 9, the thermal recorder wherein the N,N'-diarylurea compound represented by formula (1) is selected from N,N'-di-[3-(p-toluenesulfonyloxy)phenyl]urea, N,N'-di-[3-(o-toluenesulfonyloxy)phenyl]urea, N,N'-di-[3-(benzenesulfonyloxy)phenyl]urea, N,N'-di-[3-(mesitylenesulfonyloxy)phenyl]urea, N,N'-di-[3-(4-ethyl ... At least one of the following groups: -[3-(2-naphthalenesulfonyloxy)phenyl]urea, N,N'-di-[3-(p-methoxybenzenesulfonyloxy)phenyl]urea, N,N'-di-[3-(benzylsulfonyloxy)phenyl]urea, N,N'-di-[3-(ethanesulfonyloxy)phenyl]urea, N,N'-di-[3-(p-toluenesulfonyloxy)-4-methylphenyl]urea, N,N'-di-[4-(p-toluenesulfonyloxy)phenyl]urea, N,N'-di-[4-(benzenesulfonyloxy)phenyl]urea, N,N'-di-[4-(ethanesulfonyloxy)phenyl]urea, and N,N'-di-[2-(p-toluenesulfonyloxy)phenyl]urea.

[0039] Project 11

[0040] The thermal recorder according to any one of items 1 to 10, wherein the thermal recorder has an adhesive layer on at least one surface of the support.

[0041] The effects of the invention

[0042] The thermal recorder of the present invention exhibits excellent resistance to alcohol, plasticizers, and water plasticizers. Detailed Implementation

[0043] In this specification, the expression "including" or "comprising" includes the following concepts: including, substantially consisting of, and composed of.

[0044] In this specification, the numerical range referred to by "...to..." means the range of values ​​given before and after "to" as a lower limit and an upper limit.

[0045] As used in this article, "latex" includes latex in the form of a gel or dry film formed by drying the dispersion medium.

[0046] This invention relates to a thermal recorder, which comprises a base coating and a thermal recording layer sequentially on a support.

[0047] The base coat consists of hollow particles, a binder, and inorganic pigment I.

[0048] The thermal recording layer contains leuco dyes, developers, and inorganic pigment II.

[0049] The thermal recording layer contains an N,N'-diarylurea compound represented by formula (1) as a color developer, and an inorganic pigment II with an oil absorption of less than 130 ml / 100 g.

[0050]

[0051] R2 can be the same or different, and each represents C. 1-12 Straight-chain, branched, or alicyclic alkyl groups, C 7-12 Aryl or C 6-12 Aryl, and aralkyl and aryl can each be C 1-12 Alkyl, C 1-12 Alkoxy, C 6-12 Aryl or halogen substitution; A1 can be the same or different, and each represents hydrogen or C. 1-4 alkyl.

[0052] [Support body]

[0053] The support in this invention is not particularly limited in type, shape, or size. For example, high-quality paper (acidic paper, neutral paper), medium-quality paper, coated paper, art paper, cast-coated paper, translucent paper, resin-laminated paper, polyolefin synthetic paper, synthetic fiber paper, nonwoven fabric, synthetic resin film, or various transparent supports can be appropriately selected and used. The thickness of the support is not particularly limited, typically about 20 to 200 μm. The density of the support is not particularly limited, but preferably about 0.60 to 0.85 g / cm³. 3 .

[0054] [Base Coating]

[0055] The thermal recorder of the present invention includes an undercoat layer between a support and a thermal recording layer, and the undercoat layer comprises hollow particles, a binder, and an inorganic pigment I.

[0056] (Hollow particles)

[0057] From the viewpoint of enhancing buffering, the hollow particles are preferably formed of organic resin. The undercoat containing hollow particles and thus possessing excellent thermal insulation properties can prevent heat diffusion applied to the thermal recording layer and increase the sensitivity of the thermal recorder.

[0058] Based on the production method, hollow particles formed from organic resins can be divided into foamed and non-foamed types. Of these two types, foamed hollow particles generally have a larger average particle size and a higher hollowness ratio than non-foamed hollow particles. Therefore, compared to non-foamed hollow particles, foamed hollow particles offer better sensitivity and image quality.

[0059] Non-foamed hollow particles can be produced by polymerizing seeds in solution, polymerizing other resins to coat the seeds, and removing the internal seeds through swelling and dissolution to create voids inside. Internal seeds can also be removed using alkaline aqueous solutions or similar methods through swelling and dissolution. Non-foamed hollow particles with a relatively large average particle size, consisting of a core with alkali-swellable particles coated with a shell that does not alkali-swellable, can also be produced through alkali swelling treatment of the core-shell particles.

[0060] Foamed hollow granules can be produced by preparing granules in which volatile liquid is sealed in resin, and by evaporating and expanding the liquid in the granules while the resin is softened by heating.

[0061] In the production process of foamed hollow particles, heating causes the liquid inside the particles to expand, thereby increasing the hollowness and providing excellent thermal insulation. Therefore, using foamed hollow particles can improve the sensitivity of the thermal recorder and enhance recording density. This improved sensitivity is particularly important for color development in the medium energy range where the thermal energy applied to the thermal recording layer is small. Furthermore, when the thermal recording layer is formed from a base coat with excellent thermal insulation, the diffusion of heat applied to the thermal recording layer is prevented, resulting in excellent image uniformity and improved image quality. Therefore, in this embodiment, foamed hollow particles suitable for improving the thermal insulation of the base coat are preferred.

[0062] Examples of resins that can be used in foamed hollow granules include thermoplastic resins, such as styrene-acrylic resins, polystyrene resins, acrylic resins, polyethylene resins, polypropylene resins, polyacetal resins, chlorinated polyether resins, polyvinyl chloride resins, polyvinylidene chloride resins, acrylic resins (e.g., acrylic resins containing acrylonitrile as a component), styrene resins, vinylidene chloride resins, and copolymer resins mainly formed from polyvinylidene chloride and acrylonitrile. Propane, butane, isobutane, air, etc., can typically be used as the gas contained in the foamed hollow granules. From the viewpoint of maintaining the strength of the foamed granule shape, acrylonitrile resins and copolymer resins mainly formed from polyvinylidene chloride and acrylonitrile are preferred resins that can be used in hollow granules.

[0063] The maximum particle size of the hollow particles in this invention is preferably 10–40 μm, more preferably 10–30 μm, and even more preferably 15–25 μm. The maximum particle size is also referred to as "D100". When the maximum particle size of the hollow particles is 10 μm or more, the buffering properties of the undercoat are improved; therefore, the adhesion between the thermal recorder and the hothead is improved during printing, and a thermal recorder with high image quality is obtained. This high image quality can result in improved recording density at a lower energy level than that used to provide the maximum recording density (Dmax) within a medium energy range. When the maximum particle size of the hollow particles is 40 μm or less, the smoothness of the undercoat is improved; therefore, the thermal recording layer disposed between the undercoat and the thermal recorder can be made uniform, and a thermal recorder in which white spots are less likely to form in the image can be obtained.

[0064] The average particle size of the hollow particles in this invention is preferably 4.0 to 15 μm, and more preferably 7.5 to 15 μm. The average particle size used here is the diameter at which the volume of the larger particle is equal to the volume of the smaller particle when the particles are divided into two types based on particle size; that is, the median diameter, which corresponds to a frequency of 50% by volume. The average particle size is also referred to as "D50". When the average particle size of the hollow particles is 4.0 μm or more, the buffering properties of the undercoat are improved; therefore, the adhesion between the thermal recorder and the hothead is improved during printing, and a thermal recorder with high image quality is obtained. This high image quality can result in improved recording density in the medium energy range, where color development is performed at energy lower than that used to provide maximum recording density (Dmax). When the average particle size of the hollow particles is 15 μm or less, the smoothness of the undercoat is improved; therefore, the thermal recording layer disposed between the undercoat and the thermal recorder can be made uniform, and a thermal recorder in which white spots are less likely to form in the image can be obtained.

[0065] The maximum particle size (D100) and average particle size (D50) of hollow particles can be measured using a laser diffraction particle size distribution analyzer. The average particle size (D50) can be shown as the average of the particle sizes of 10 particles, measured from electron microscope images (SEM images) of each particle.

[0066] The ratio of the maximum particle size (D100) to the average particle size (D50) of the hollow particles, i.e., D100 / D50, is an indicator of the degree of particle size distribution. The D100 / D50 ratio is preferably 1.8 to 3.0, and more preferably 2.0 to 2.8. When the D100 / D50 ratio of the hollow particles is 1.8 or higher, the hollow particles can be fully foamed, the maximum particle size can be sufficiently large, the hollow particle ratio can be high, and the thermal insulation of the undercoat can be improved. When the D100 / D50 ratio of the hollow particles is 3.0 or lower, the size of the hollow particles is uniform, which improves the smoothness of the undercoat and suppresses white spots in the image.

[0067] In the particle size distribution measured using a laser diffraction particle size distribution analyzer, the volume percentage of hollow particles with a diameter of 2.0 μm or less is preferably 1% or less. It is also preferable that the volume percentage of hollow particles with a diameter of 2.0 μm or less is 0.5%, and more preferably, hollow particles with a diameter of 2.0 μm or less are not included. Hollow particles with a diameter of 2 μm or less are considered to contribute very little to thermal insulation because they are too small to have sufficient hollow space. When the volume percentage of hollow particles with a diameter of 2 μm or less in the undercoat is 1% or less, the recording density, image quality, etc., can be improved.

[0068] The hollowness of the hollow particles is preferably 80-98%, and more preferably 90-98%. When the hollowness of the hollow particles is 80% or more, the base coating containing the hollow particles can be endowed with excellent thermal insulation properties. When the hollowness of the hollow particles is 98% or less, the strength of the film around the hollow portion is improved, and thus hollow particles that do not collapse even when the base coating is formed can be obtained.

[0069] The hollowness of the hollow particles was determined by measuring the true specific gravity according to the IPA method, and the true specific gravity value was used as follows.

[0070] (1) Sample pretreatment

[0071] The sample was dried at 60°C for 24 hours.

[0072] (2) Reagents

[0073] Isopropanol (IPA: Ultrapure Reagent)

[0074] (3) Measurement method

[0075] - Weighing volumetric flask (W1).

[0076] Weigh approximately 0.5 g of the dried sample (W2) into a volumetric flask.

[0077] Add approximately 50 mg of IPA to the flask and shake the volumetric flask thoroughly to completely remove any air from the capsule.

[0078] - Add IPA to the mark line and weigh the volumetric flask (W3).

[0079] - As a blank, add IPA separately to the mark line of the volumetric flask and weigh the volumetric flask (W4).

[0080] (4) Calculation of true specific gravity

[0081] True specific gravity = {(W2-W1)×((W4-W1) / 100)} / {(W4-W1)-(W3-W2)}

[0082] (5) Calculation of hollow ratio

[0083] Hollow content (%) = {1 - 1 / (1.1 / true specific gravity)} × 100

[0084] The hollow ratio can also be calculated using the following formula: (d 3 / D 3 )×100. In the formula, d represents the inner diameter of the hollow particle, and D represents the outer diameter of the hollow particle.

[0085] Because the hollow particles in this invention have a relatively large particle size, the content of hollow particles in the primer coating can be reduced. The content of hollow particles, based on the total solid content of the primer coating, is preferably 3 to 40% by mass, and more preferably 5 to 35% by mass. A hollow particle content of 3% by mass or more can improve the thermal insulation of the primer coating, while a hollow particle content of 40% by mass or less makes it less likely to cause problems such as coatability, and allows for easy formation of a uniform primer coating and improved recording concentration. Furthermore, the film strength of the primer coating can be improved.

[0086] (Adhesive)

[0087] Examples of binders include water-soluble polymers such as polyvinyl alcohol and its derivatives, starch and its derivatives, cellulose derivatives such as hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose and ethyl cellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide-acrylate copolymer, acrylamide-acrylate-methacrylate copolymer, styrene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, casein, gelatin and its derivatives; emulsions such as polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylate, vinyl chloride-vinyl acetate copolymer, polybutyl methacrylate and ethylene-vinyl acetate copolymer, etc.; and latexes of water-insoluble polymers such as styrene-butadiene copolymer and styrene-butadiene-acrylic acid copolymer; etc. Among these, binders containing latex are preferred. The content of the binder can be selected from a wide range, and is generally preferably about 20 to 70% by mass, and more preferably about 25 to 60% by mass, based on the total solid content of the base coat.

[0088] The glass transition temperature (Tg) of the adhesive is not particularly limited, but is preferably below -10°C. When the glass transition temperature is below -10°C, image quality can be improved even in the low energy range. A glass transition temperature below -30°C is more preferred, as image quality can be further improved in the low energy range. Glass transition temperatures below -50°C are undesirable because adhesion will occur. Therefore, a glass transition temperature above -40°C is preferred.

[0089] (Inorganic Pigment I)

[0090] The base coating of this invention comprises inorganic pigment I. From the viewpoint of increasing recording concentration and improving water plasticizer resistance and alcohol resistance, the oil absorption of inorganic pigment I is preferably 130 ml / 100g or less, more preferably 125 ml / 100g or less, and even more preferably 110 ml / 100g or less. From the viewpoint of effectively reducing printing problems such as tip residue and adhesion, the oil absorption of inorganic pigment I is also preferably 50 ml / 100g or more, and more preferably 80 ml / 100g or more. The oil absorption is a value measured according to the method of JIS K5101.

[0091] Various inorganic pigments can be used as inorganic pigment I, with calcined kaolin, clay, etc. being preferred. From the viewpoint of improving water resistance, plasticizer resistance, and alcohol resistance, the content of inorganic pigment I based on the total solids content of the undercoat is preferably 60% by mass or less, and more preferably 50% by mass or less. From the viewpoint of effectively reducing printing problems such as tip residue and adhesion, the content of inorganic pigment I based on the total solids content of the undercoat is also preferably 20% by mass or more, and more preferably 25% by mass or more.

[0092] For example, a primer coating is prepared by mixing hollow particles, a binder, inorganic pigment I, and necessary additives using water as a medium. The coating is then applied to a support and dried to form a primer coating on the support. The amount of primer coating is not particularly limited, but is preferably about 2 to 20 g / m³ based on dried mass. 2 More preferably about 2 to 12 g / m 2 .

[0093] [Thermal Recording Layer]

[0094] (Leuco dye)

[0095] The thermal recording layer of the thermal recorder of the present invention can contain any of a variety of known colorless or light-colored leuco dyes. Specific examples of such leuco dyes are described below.

[0096] Specific examples of leuco dyes include blue chromogenic dyes such as 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, 3-(4-diethylamino-2-methylphenyl)-3-(4-dimethylaminophenyl)-6-dimethylaminophthalide, and fluorane; green chromogenic dyes such as 3-(N-ethyl-N-p-tolyl)amino-7-N-methylaniline fluorane, 3-diethylamino-7-aniline fluorane, 3-diethylamino-7-dibenzylaminofluorane, and rhodamine B-aniline lactam; and red chromogenic dyes such as 3,6-bis(diethylamino)fluorane-γ-aniline lactam, 3-cyclohexylamino-6-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, and 3-diethylamino-7-chlorofluorane.Black chromogenic dyes, such as 3-(N-ethyl-N-isopentyl)amino-6-methyl-7-aniline fluorane, 3-(N-methyl-N-cyclohexyl)amino-6-methyl-7-aniline fluorane, 3-diethylamino-6-methyl-7-aniline fluorane, 3-di(n-butyl)amino-6-methyl-7-aniline fluorane, 3-di(n-pentyl)amino-6-methyl-7-aniline fluorane, 3-(N-ethyl-N-isopentylamino-6-methyl-7-aniline fluorane, 3-diethylamino-7-(m-trifluoromethylaniline)fluorane, 3-(N-isopentyl-N-ethylamino)-7-(o-chloroaniline)fluorane, 3-(N 3-(N-hexyl-N-ethylamino)-6-methyl-7-aniline fluorane, 3-[N-(3-ethoxypropyl)-N-ethylamino]-6-methyl-7-aniline fluorane, 3-[N-(3-ethoxypropyl)-N-methylamino]-6-methyl-7-aniline fluorane, 3-diethylamino-7-(2-chloroaniline)fluorane, 3-di(n-butylamino)-7-(2-chloroaniline)fluorane, 4,4'-bis-dimethylaminobenzodihydroindene benzyl ether, N-2,4,5-trichlorophenyllylamine, 3-diethylamino-7-butylamino Fluorane, 3-ethyl-tolylamino-6-methyl-7-anilinofluorane, 3-cyclohexyl-methylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-chloro-7-(β-ethoxyethyl)aminofluorane, 3-diethylamino-6-chloro-7-(γ-chloropropyl)aminofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-(N-isopentyl-N-ethylamino)-6-methyl-7-anilinofluorane, 3-dibutylamino-7-chloroanilinofluorane, 3-diethylamino-7-(o-chlorophenylamino)fluorane, 3-(N-ethyl-p-tolyl)-6-methyl-7-anilinofluorane, 3-(N- Ethyl-p-toluidine)-6-methyl-7-(p-toluidine)fluorane, 3-(N-ethyl-N-tetrahydrofurfurylamino)-6-methyl-7-aniline fluorane, 3-diethylamino-6-chloro-7-aniline fluorane, 3-dimethylamino-6-methyl-7-aniline fluorane, 3-pyrrolidinyl-6-methyl-7-aniline fluorane, 3-piperidinyl-6-methyl-7-aniline fluorane, 2,2-bis{4-[6'-(N-cyclohexyl-N-methylamino)-3'-methylspiro[phthalide-3,9'-xanthonone-2'-ylamino]phenyl}propane and 3-diethylamino-7-(3'-trifluoromethylphenyl)amino fluorane;Dyes with absorption wavelengths in the near-infrared region include, for example, 3,3-bis[1-(4-methoxyphenyl)-1-(4-dimethylaminophenyl)ethyl-2-yl]-4,5,6,7-tetrachlorophthalic acid ester, 3,3-bis[1-(4-methoxyphenyl)-1-(4-pyrrolidinephenyl)ethyl-2-yl]-4,5,6,7-tetrachlorophthalic acid ester, 3-p-(p-dimethylaminoanilino)anilino-6-methyl-7-chlorofluorane, 3-p-(p-chloroanilino)anilino-6-methyl-7-chlorofluorane, and 3,6-bis(dimethylamino)fluorene-9-spiro-3'-(6'-dimethylamino)phthalide; etc. Of course, the available leuco dyes are not limited to these compounds, and two or more such compounds can be used in combination as needed.

[0097] There is no particular limitation on the content of the leuco dye, and the total solid content based on the thermal recording layer is preferably about 3 to 30% by mass, more preferably about 5 to 25% by mass, and even more preferably about 7 to 20% by mass. A leuco dye content of 3% by mass or more can improve the color development ability, thereby improving the recording concentration, while a leuco dye content of less than 30% by mass can improve the heat resistance.

[0098] (Color developer)

[0099] In this invention, an N,N'-diarylurea compound represented by formula (1) is used as a colorimetric agent. Using N,N'-diarylurea compounds can exhibit excellent resistance to alcohols, plasticizers, and water-based plasticizers.

[0100] C represented by R2 1-12 Alkyl groups can be straight-chain, branched, or alicyclic, preferably C12-24-24-3 ...5-34-34-35-34-35-34 1-6 Alkyl, and more preferably C 1-3 Alkyl group. C 1-12 Examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclopentyl, hexyl, cyclohexyl, 2-ethylhexyl, and lauryl. Alkyl groups as used herein include C14. 1-12 The alkyl moiety of alkoxy groups.

[0101] "Arylalkyl" refers to arylalkyl groups. C 7-12 Examples of aralkyl groups include benzyl, 1-phenylethyl, 2-phenylethyl, and 3-phenylpropyl.

[0102] "Aryl" refers to a monocyclic or polycyclic group formed from a 5- or 6-membered aromatic hydrocarbon ring. 6-12 Examples of aryl groups include phenyl, 1-naphthyl, and 2-naphthyl. The aryl groups used herein include the aryl moiety of aralkyl groups.

[0103] Examples of halogens include fluorine, chlorine, bromine, and iodine.

[0104] In equation (1), the substitution positions of each R2-SO3- can be the same or different. The substitution positions are preferably at the 3-position, 4-position, or 5-position, and more preferably at the 3-position. When C represented by R2... 7-12 Arane and C 6-12 When the aryl group is substituted, there is no particular limitation on the number of substituents, and for example, it can be 1 to 4.

[0105] C represented by A1 1-4 Alkyl groups can be straight-chain or branched. Examples include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, and tert-butyl.

[0106] The substitution positions of each A1 can be the same or different. The substitution positions are preferably 3-position, 4-position or 5-position.

[0107] There are no particular limitations on the N,N'-diarylurea compounds represented by formula (1), and they are preferably selected from N,N'-di-[3-(p-toluenesulfonyloxy)phenyl]urea, N,N'-di-[3-(o-toluenesulfonyloxy)phenyl]urea, N,N'-di-[3-(benzenesulfonyloxy)phenyl]urea, N,N'-di-[3-(tris(toluenesulfonyloxy)phenyl]urea, N,N'-di-[3-(4-ethylbenzenesulfonyloxy)phenyl]urea, N,N'-di-[3-(2-naphthalenesulfonyloxy)phenyl]urea, N,N'-di-[3-(p-toluenesulfonyloxy)phenyl]urea, N,N'-di-[3-(4-ethylbenzenesulfonyloxy)phenyl]urea, N,N'-di-[3-(2-naphthalenesulfonyloxy)phenyl]urea, N,N'-di-[3-(p-toluenesulfonyloxy)phenyl]urea, N,N'-di-[3-(4-ethylbenzenesulfonyloxy)phenyl]urea, N,N'-di-[3-(2-naphthalenesulfonyloxy)phenyl]urea, N,N'-di-[3-(4-ethylbenzene ... At least one of the following groups: [methoxybenzenesulfonyloxy]phenyl]urea, N,N'-di-[3-(benzylsulfonyloxy)phenyl]urea, N,N'-di-[3-(ethanesulfonyloxy)phenyl]urea, N,N'-di-[3-(p-toluenesulfonyloxy)-4-methylphenyl]urea, N,N'-di-[4-(p-toluenesulfonyloxy)phenyl]urea, N,N'-di-[4-(benzenesulfonyloxy)phenyl]urea, N,N'-di-[4-(ethanesulfonyloxy)phenyl]urea, and N,N'-di-[2-(p-toluenesulfonyloxy)phenyl]urea. N,N'-di-[3-(p-toluenesulfonyloxy)phenyl]urea is preferred.

[0108] The content of N,N'-diarylurea compounds is not particularly limited and can be adjusted according to the leuco dye used. The content of N,N'-diarylurea compounds relative to 1 part by mass of leuco dye is generally preferably 0.5 parts by mass or more, more preferably 0.8 parts by mass or more, even more preferably 1 part by mass or more, even more preferably 1.2 parts by mass or more, and particularly preferably 1.5 parts by mass or more. The content of N,N'-diarylurea compounds relative to 1 part by mass of leuco dye is also preferably 10 parts by mass or less, more preferably 5 parts by mass or less, even more preferably 4 parts by mass or less, and particularly preferably 3.5 parts by mass or less. A content of 0.5 parts by mass or more of N,N'-diarylurea compounds can improve recording performance, while a content of 10 parts by mass or less of N,N'-diarylurea compounds can effectively suppress background fogging in high-temperature environments.

[0109] The thermal recording layer of the present invention preferably further comprises, as a second color developer, at least one of the following groups: 4,4'-bis[(4-methyl-3-phenoxycarbonylaminophenyl)ureo]diphenyl sulfone, 4,4'-bis[(2-methyl-5-phenoxycarbonylaminophenyl)ureo]diphenyl sulfone, 4-(2-methyl-3-phenoxycarbonylaminophenyl)ureo-4'-(4-methyl-5-phenoxycarbonylaminophenyl)ureodiphenyl sulfone, crosslinked diphenyl sulfone compounds represented by formula (3), and 4,4'-bis(3-tolylureo)diphenylmethane. The use of a second color developer can further improve water resistance and plasticizer resistance. The content of the second color developer is preferably about 0.2 to 3 parts by mass relative to 1 part by mass of the leuco dye. The content of the second color developer is also preferably about 0.2 to 0.5 parts by mass relative to 1 part by mass of the N,N'-diarylureate compound used as the first color developer.

[0110] Other colorimetric agents may be included, provided that the effects of the invention are not impaired. Specific examples of other colorimetric agents include phenolic compounds, such as 4-tert-butylphenol, 4-acetylphenol, 4-tert-octylphenol, 4,4'-sec-butylidene diphenol, 4-phenylphenol, 4,4'-dihydroxydiphenylmethane, 4,4'-isopropylidene diphenol, 4,4'-cyclohexylene biphenyl, 4,4'-cyclohexylene diphenol, 1,1-bis(4-hydroxyphenyl)-ethane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, 4,4'-bis(p-toluenesulfonylaminocarbonylamino)diphenylmethane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 2,2'-bis[4-(4-hydroxyphenyl)phenoxy]diethyl ether, 4, 4'-Dihydroxydiphenyl sulfide, 4,4'-thiobis(3-methyl-6-tert-butylphenol), 4,4'-dihydroxydiphenyl sulfone, 2,4'-dihydroxydiphenyl sulfone, 2,2-bis(4-hydroxyphenyl)-4-methylpentane, 2,4'-dihydroxydiphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone, 4-hydroxy-4'-n-propoxydiphenyl sulfone, 4-hydroxy-4'-allyloxydiphenyl sulfone, 4-hydroxy-4'-benzyloxydiphenyl sulfone, 3,3'-diallyl-4,4'-dihydroxydiphenyl sulfone, bis(p-hydroxyphenyl)acetic acid butyl ester, bis(p-hydroxyphenyl)acetic acid methyl ester, hydroquinone monobenzyl ether, bis(3-allyl) 4-Hydroxyphenyl sulfone, 4-hydroxy-4'-methyldiphenyl sulfone, 4-allyloxy-4'-hydroxydiphenyl sulfone, 3,4-dihydroxyphenyl-4'-methylphenyl sulfone, 4-hydroxybenzophenone, dimethyl 4-hydroxyphthalate, methyl 4-hydroxybenzoate, propyl 4-hydroxybenzoate, sec-butyl 4-hydroxybenzoate, phenyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, toluene 4-hydroxybenzoate, chlorophenyl 4-hydroxybenzoate, and 4,4'-dihydroxydiphenyl ether; aromatic carboxylic acids, such as benzoic acid, p-chlorobenzoic acid, p-tert-butylbenzoic acid, toluenechlorobenzoic acid, terephthalic acid, and salicylic acid. 3-tert-butylsalicylic acid, 3-isopropylsalicylic acid, 3-benzylsalicylic acid, 3-(α-methylbenzyl)salicylic acid, 3,5-di-tert-butylsalicylic acid, 4-[2-(p-methoxyphenoxy)ethoxy]salicylic acid, 4-[3-(p-toluenesulfonyl)propoxy]salicylic acid, 5-[p-(2-p-methoxyphenoxyethoxy]cumyl]salicylic acid, and zinc 4-{3-(p-toluenesulfonyl)propoxy]salicylic acid; salts of these phenolic compounds or aromatic carboxylic acids with polyvalent metals such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin, and nickel; antipyrine complexes of zinc thiocyanate; complex zinc salts of organic acids such as terephthalic acid and other aromatic carboxylic acids;Thiourea compounds, such as N-p-toluenesulfonyl-N'-3-(p-toluenesulfonyloxy)phenylurea, N-p-toluenesulfonyl-N'-p-butoxycarbonylphenylurea, N-p-toluenesulfonyl-N'-phenylurea, and N,N'-di-m-chlorophenylthiourea; organic compounds having a -SO2NH- bond in the molecule, such as N-(p-toluenesulfonyl)carbamate p-cumylphenyl ester, N-(p-toluenesulfonyl)carbamate p-benzyloxyphenyl ester, N-[2-(3-phenylureo)phenyl]benzenesulfonamide, and N-(o-toluyl)-p-toluenesulfonamide; inorganic acidic substances, such as activated clay, attapulgite, colloidal silica, and aluminum silicate; etc. The content of other color-developing agents is not particularly limited, and is preferably 0.2 parts by mass or less, and more preferably 0.1 parts by mass or less, relative to 1 part by mass of the N,N'-diarylurea compound used as the first color-developing agent.

[0111] (Inorganic Pigment II)

[0112] The thermal recording layer of the present invention comprises an inorganic pigment II with an oil absorption of 130 ml / 100 g or less. The oil absorption of the inorganic pigment II is preferably 125 ml / 100 g or less, more preferably 100 ml / 100 g or less, even more preferably 60 ml / 100 g or less, particularly preferably 50 ml / 100 g or less, and most preferably 45 ml / 100 g or less. Using inorganic pigment II can significantly improve resistance to alcohol, plasticizers, and water plasticizers. From the viewpoint of effectively reducing printing problems such as printhead residue and adhesion, the oil absorption of the inorganic pigment II is preferably 30 ml / 100 g or more. Without compromising the effects of the present invention, the thermal recording layer of the present invention may comprise a pigment with an oil absorption greater than 130 ml / 100 g. The content of pigment with an oil absorption greater than 130 ml / 100 g is preferably 0.5 parts by weight or less, more preferably 0.3 parts by weight or less, and even more preferably 0.1 parts by weight or less, relative to 1 part by weight of pigment with an oil absorption of less than 130 ml / 100 g. Particularly preferred is that the thermal recording layer does not contain pigment with an oil absorption greater than 130 ml / 100 g. The oil absorption is a value determined according to the method of JIS K5101.

[0113] Various inorganic pigments can be used as inorganic pigment II. Specific examples include inorganic pigments such as calcium carbonate (e.g., light calcium carbonate), aluminum hydroxide, clay (e.g., kaolin), and talc. Inorganic pigment II is preferably at least one selected from the group consisting of calcium carbonate, aluminum hydroxide, and clay. The type of inorganic pigment II may be different from or the same as inorganic pigment I. The content of inorganic pigment II can be selected from a wide range, and the total solid content based on the thermal recording layer is preferably 10–50% by mass, more preferably 10–40% by mass, and even more preferably 15–35% by mass.

[0114] In this invention, the thermal recording layer may further contain a stabilizer, primarily to further enhance the preservation of the colorimetric image. Such stabilizers can be selected from phenolic compounds, such as 1,1,3-tris(2-methyl-4-hydroxy-5-cyclohexylphenyl)butane, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,1-bis(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 4,4'-[1,4-phenylenebis(1-methylethylene)]bisphenol and 4,4'-[1,3-phenylenebis(1-methylethylene)]bisphenol. [1-Methylethylidene] bisphenol; epoxy compounds, such as 4-benzyloxyphenyl-4'-(2-methyl-2,3-epoxypropoxy)phenyl sulfone, 4-(2-methyl-1,2-epoxyethyl)diphenyl sulfone, and 4-(2-ethyl-1,2-epoxyethyl)diphenyl sulfone; and isocyanuric acid compounds, such as at least one of the group consisting of 1,3,5-tris(2,6-dimethylbenzyl-3-hydroxy-4-tert-butyl)isocyanuric acid. Of course, the stabilizers available are not limited to these compounds, and two or more such compounds may be used in combination as needed.

[0115] When a stabilizer is used, the amount can be an effective amount for improving image preservation. The stabilizer is generally preferably used in an amount of about 1 to 25% by mass, and more preferably about 5 to 20% by mass, based on the total solid content of the thermal recording layer.

[0116] In this invention, the thermal recording layer may further comprise a sensitizer. The use of a sensitizer improves recording sensitivity. Examples of usable sensitizers include stearamide, methoxycarbonyl-N-stearamide, N-benzoylstearamide, N-eicosanoamide, ethylene bis-stearamide, benzylamide, methylene bis-stearamide, N-hydroxymethylstearamide, dibenzyl terephthalate, dimethyl terephthalate, dioctyl terephthalate, diphenyl sulfone, benzyl p-benzyloxybenzoate, 1-hydroxy-2-naphthoic acid phenyl ester, 2-naphthyl benzyl ether, m-terphenyl, p-benzyl biphenyl, di-p-chlorobenzyl oxalate, di-p-methylbenzyl oxalate, dibenzyl oxalate, p-tolyl diphenyl ether, di(p-methoxyphenoxyethyl) ether, 1,2-di(3-methylphenoxy)ethane, 1,2-di( 4-Methylphenoxy)ethane, 1,2-di(4-methoxyphenoxy)ethane, 1,2-di(4-chlorophenoxy)ethane, 1,2-diphenoxyethane, 1-(4-methoxyphenoxy)-2-(3-methylphenoxy)ethane, p-methylthiophenyl benzyl ether, 1,4-di(phenylthio)butane, p-acetyltoluidine, p-ethoxyacetylaniline, N-acetylacetyl-p-toluidine, 1,2-diphenoxytoluene, di(β-biphenylethoxy)benzene, p-di(ethyleneoxyethoxy)benzene, 1-isopropylphenyl-2-phenylethane, di-o-chlorobenzyl adipic acid, 1,2-bis(3,4-dimethylphenyl)ethane, 1,3-bis(2-naphthoxy)propane, biphenyl, and benzophenone, etc. From the viewpoint of achieving sensitization without reducing resistance to water plasticizers and alcohol, 1,2-bis(3-methylphenoxy)ethane is preferred. These sensitizers can be used in combination, as long as the combination does not impair the effectiveness of the invention. The content of the sensitizer can be the effective amount for sensitization, and is generally preferred to be 2-25% by mass, more preferably 5-20% by mass, and even more preferably 5-15% by mass, based on the total solid content of the thermal recording layer.

[0117] As other components constituting the thermal recording layer, binders can be used. Additionally, depending on the requirements, additives such as crosslinking agents, waxes, metal soaps, water resistance improvers, dispersants, colored dyes, and fluorescent dyes can be used.

[0118] Examples of binders include water-soluble polymers such as polyvinyl alcohol and its derivatives, starch and its derivatives, cellulose derivatives such as hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose and ethyl cellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide-acrylate copolymers, acrylamide-acrylate-methacrylate copolymers, styrene-maleic anhydride copolymers, isobutylene-maleic anhydride copolymers, casein, gelatin and its derivatives; emulsions such as polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylate, vinyl chloride-vinyl acetate copolymers, polybutyl methacrylate, and ethylene-vinyl acetate copolymers; and latexes of water-insoluble polymers such as styrene-butadiene copolymers and styrene-butadiene-acrylic copolymers; etc. Polyvinyl alcohol and latexes are preferred. The content of the binder can be selected from a wide range, and is generally preferred to be about 5 to 30% by mass based on the total solid content of the thermal recording layer, and more preferably about 10 to 20% by mass.

[0119] When the thermal recording layer contains a crosslinking agent, the water resistance of the thermal recording layer can be improved. Examples of crosslinking agents include aldehyde compounds, such as glyoxal; polyamine compounds, such as polyethyleneimine; epoxy compounds, polyamide resins, melamine resins, glyoxylates, dimethylolurea compounds, aziridine compounds, and capped isocyanate compounds; and inorganic compounds, such as ammonium persulfate, ferric chloride, magnesium chloride, sodium tetraborate, and potassium tetraborate; as well as boric acid, triborate, boron polymers, hydrazide compounds, and glyoxylates. These can be used alone or in combination of two or more. The amount of crosslinking agent used is preferably about 1 to 5% by mass based on the total solid content of the thermal recording layer.

[0120] The thermal recording layer is formed on the base layer as follows: For example, using water as the dispersion medium and employing at least one of various agitators or wet mills, such as ball mills, co-ball mills, grinders, or vertical or horizontal sand mills, a leuco dye and a color developer, along with, as needed, a sensitizer and a stabilizer, together or separately, a water-soluble synthetic polymer such as polyacrylamide, polyvinylpyrrolidone, polyvinyl alcohol, methylcellulose, or styrene-maleic anhydride copolymer salts, and other additives such as surfactants, to form a dispersion; then, the dispersion obtained by reducing the average particle size to less than 2 μm is mixed with inorganic pigment II, and optionally further mixed with a binder and additives to prepare a coating for the thermal recording layer; the coating for the thermal recording layer is applied onto the base layer and then dried. There is no particular limitation on the amount of thermal recording layer applied, but for the amount applied after drying, approximately 1 to 12 g / m² is preferred. 2 More preferably 2-10 g / m 2 Even more preferably, it is 2.5–8 g / m³.2 And particularly preferred is 3-5.5 g / m 2 Note that, as needed, the thermal recording layer can be formed as two or more separate layers, and the composition and coating amount of each layer can be the same or different.

[0121] [Protective Layer]

[0122] As needed, the thermal recorder may include a protective layer formed on the thermal recording layer. The protective layer preferably comprises pigments and binders. The protective layer preferably further comprises a lubricant, such as a polyolefin wax or zinc stearate, to prevent the protective layer from adhering to the hot head. The protective layer may also contain a UV absorber. When a glossy protective layer is formed, the resulting product can have increased added value.

[0123] There are no particular limitations on the pigments contained in the protective layer. Examples include inorganic pigments such as amorphous silica, kaolin, clay, light calcium carbonate, ground calcium carbonate, calcined kaolin, titanium dioxide, magnesium carbonate, aluminum hydroxide, colloidal silica, and synthetic layered mica; and plastic pigments such as urea-formaldehyde resin fillers; etc.

[0124] There are no particular limitations on the adhesive contained in the protective layer, and an aqueous adhesive selected from water-soluble and water-dispersible adhesives can be used. The adhesive can be suitably selected from adhesives that can be used in thermal recording layers. Among these adhesives, modified polyvinyl alcohol, such as acetoacetyl-modified polyvinyl alcohol, carboxyl-modified polyvinyl alcohol, and diacetone-modified polyvinyl alcohol, is more preferred.

[0125] For example, a protective layer coating is prepared by mixing pigments and binders, optionally with additives, using water as a dispersion medium. The coating is then applied to a thermal recording layer and dried to form a protective layer on the thermal recording layer. There are no particular limitations on the coating amount, but it is preferably about 0.3 to 15 g / m² on a dry weight basis. 2 More preferably about 0.3 to 10 g / m 2 Even more preferred is approximately 0.5–8 g / m 2 A particularly preferred concentration is approximately 1–8 g / m³. 2 Furthermore, it is particularly preferred to have a concentration of approximately 1–5 g / m³. 2 Depending on the requirements, the protective layer can be formed into two or more separate layers, and the composition and coating amount of each layer can be the same or different.

[0126] [Other layers]

[0127] In this invention, the thermal recorder preferably has an adhesive layer on at least one surface of the support. This can increase the added value of the thermal recorder. For example, adhesive paper, rewet adhesive paper, or delayed adhesive paper can be formed as an adhesive layer by coating one surface of the support with an adhesive such as an adhesive, rewet adhesive, or delayed adhesive type adhesive. Recording paper capable of double-sided recording can also be formed by giving the surface of the support opposite the thermal recording layer the function of thermal transfer paper, inkjet recording paper, carbonless paper, electrostatic recording paper, or electrostatic copying paper. Of course, the thermal recorder can be formed as a double-sided thermal recorder. A back layer can also be provided to inhibit the penetration of oil and plasticizers from the back of the thermal recorder, or for curl control and antistatic purposes. The thermal recorder can also be formed as a linerless label that does not require a release liner by forming a silicone-containing release layer on a protective layer and applying an adhesive on one side.

[0128] [Thermal recording medium]

[0129] Thermal recorders can be manufactured by forming the aforementioned layers on a support. Any known coating method, such as air knife coating, doctor blade coating, gravure coating, roller coating, spray coating, dip coating, rod coating, curtain coating, groove coating, slip coating, and extrusion, can be used to form the aforementioned layers on the support. Individual coatings can be applied and dried in sequence, followed by a second coating and drying, to form layer after layer, or the same coating can be applied individually to form two or more layers. Furthermore, simultaneous multilayer coating can be performed, where all coatings are applied at once to simultaneously form two or more layers. After the formation of each layer or at any stage after all layers have been formed, the layers can be smoothed using known methods such as ultracalendering or soft calendering.

[0130] Example

[0131] The invention is described in more detail below with reference to embodiments. However, the invention is not limited to these embodiments. In the embodiments, unless otherwise stated, “parts” and “%” mean “parts by mass” and “% by mass”. Particle size, such as average particle size and maximum particle size, was measured using a SALD2200 laser diffraction particle size distribution analyzer (manufactured by Shimadzu Corporation). As used herein, “average particle size” refers to the median diameter (D50).

[0132] The hollow particles used in the examples and comparative examples are as follows.

[0133] Hollow Particle A: Average particle size (D50): 5.0 μm; Maximum particle size (D100): 13.5 μm; Hollowness ratio: 90%; Proportion of particles with a diameter of less than 2 μm: 0.2% by volume; Solid content concentration: 15.0%; Foamed type.

[0134] Hollow Particles B: Average particle size (D50): 11 μm; Maximum particle size (D100): 23 μm; Hollowness ratio: 93%; Proportion of particles with a diameter of less than 2 μm: 0% by volume; Solid content concentration: 15.0%; Foamed type.

[0135] Hollow Particles C: Trade name: Ropaque SN-1055, manufactured by Dow Chemical Company; Average particle size (D50): 1.0 μm; Maximum particle size (D100): 1.8 μm; Hollowness ratio: 55%; Proportion of particles with a diameter of less than 2 μm: 100 vol%; Solid content: 26.5%; Non-foaming type.

[0136] The average particle size (D50) and maximum particle size (D100) of these hollow particles were measured using a SALD2200 laser diffraction particle size distribution analyzer (manufactured by Shimadzu Corporation) at refractive indices of 1.70–0.01i.

[0137] The latex used in the examples and comparative examples is as follows.

[0138] Latex A: Styrene-butadiene copolymer latex development product (Tg: -35℃; Particle size: 300nm; Solid content concentration: 48%)

[0139] Latex B: Styrene-butadiene copolymer latex development product (Tg: -10℃; Particle size: 190nm; Solid content concentration: 48%)

[0140] Latex C: Styrene-butadiene copolymer latex (trade name: L-1571, manufactured by Asahi Kasei Corporation; Tg: -3℃; particle size: 190nm; solid content: 48%)

[0141] The inorganic pigment II used in the examples and comparative examples is as follows.

[0142] Aluminum hydroxide: Trade name: Higilite H-42, manufactured by Showa Denko KK; Oil absorption: 43ml / 100g

[0143] Calcium carbonate: Trade name: Brilliant-15, manufactured by Shiraishi Kogyo Kaisha, Ltd.; Oil absorption: 56ml / 100g

[0144] Clay: Product name: Hydragloss 90, manufactured by KaMin LLC; Oil absorption: 46ml / 100g

[0145] Amorphous silica: Trade name: Nipsil E743, manufactured by Tosoh Silica Corporation; Oil absorption: 160ml / 100g

[0146] (Example 1)

[0147] (1) Preparation of coating for primer layer

[0148] A base coat coating was prepared by mixing and stirring 100 parts of hollow particles A, 38 parts of calcined kaolin (trade name: Ansilex 93, manufactured by BASF; oil absorption: 105 ml / 100 g) as inorganic pigment I, 79.2 parts of latex A, 32 parts of 25% oxidized starch solution, 1.1 parts of carboxymethyl cellulose (trade name: Cellogen AG gum, manufactured by DKS Co., Ltd.), and 100 parts of water.

[0149] (2) Preparation of leuco dye dispersion (liquid A)

[0150] 40 parts of 3-di(n-butyl)amino-6-methyl-7-aniline fluorane, 40 parts of 10% polyvinyl alcohol aqueous solution (degree of polymerization: 500; degree of saponification: 88%), and 20 parts of water were mixed. The resulting mixture was pulverized using a sand mill (manufactured by Imex Co., Ltd.) to an average particle size of 0.5 μm to obtain a leuco dye dispersion (liquid A).

[0151] (3) Preparation of colorimetric reagent dispersion (liquid B)

[0152] 40 parts of N,N'-bis-[3-(p-toluenesulfonyloxy)phenyl]urea, 40 parts of 10% polyvinyl alcohol aqueous solution (degree of polymerization: 500; degree of saponification: 88%), and 20 parts of water were mixed. The resulting mixture was pulverized using a sand mill (manufactured by Imex Co., Ltd.) to an average particle size of 1.0 μm to obtain a color developer dispersion (liquid B).

[0153] (4) Preparation of sensitizer dispersion (liquid C)

[0154] 40 parts of 1,2-bis(3-methylphenoxy)ethane (trade name: KS-232, manufactured by Sankosha Co., Ltd.), 40 parts of a 10% aqueous solution of polyvinyl alcohol (degree of polymerization: 500; degree of saponification: 88%), and 20 parts of water were mixed. The resulting mixture was pulverized using a sand mill (manufactured by Imex Co., Ltd.) to an average particle size of 1.0 μm to obtain a sensitizer dispersion (liquid C).

[0155] (5) Preparation of coatings for thermal recording layers

[0156] A coating for thermal recording layers was prepared by mixing and stirring 31.8 parts of liquid A, 63.6 parts of liquid B, 22.7 parts of liquid C, 46.7 parts of a 15% fully saponified aqueous solution of polyvinyl alcohol (trade name: PVA110; degree of saponification: 99 mol%; average degree of polymerization: 1000; manufactured by Kuraray Co., Ltd.), 14.6 parts of styrene-butadiene copolymer latex (trade name: L-1571; manufactured by Asahi Kasei Corporation; solid content concentration: 48%), 32 parts of aluminum hydroxide (trade name: Higilite H-42; manufactured by Showa Denko KK), 2 parts of adipic acid dihydrazide (manufactured by Otsuka Chemical Co., Ltd.), and 200 parts of water.

[0157] (6) Preparation of coating for protective layer

[0158] A composition comprising 300 parts of 12% diacetone-modified polyvinyl alcohol (trade name: DF-10, manufactured by Japan Vam & Poval Co., Ltd.), 62 parts of clay (trade name: Hydragloss 90, manufactured by KaMin LLC), 0.5 parts of polyethylene wax (trade name: Chemipearl W-400, manufactured by Mitsui Chemicals Inc.; solid content concentration: 40%), 5 parts of zinc stearate (trade name: Hidorin Z-8-36, manufactured by Chukyo Yushi Co., Ltd.; solid content concentration: 36%) and 150 parts of water is mixed and stirred to obtain a coating for protective layer.

[0159] (7) Production of thermal recording devices

[0160] The coatings for the base layer, thermal recording layer, and protective layer were each applied at a dry weight of 4.5 g / m². 2 3.5g / m 2 and 2.5g / m 2 Coated to a basis weight of 60 g / m 2 A high-quality paper is applied to one surface and dried to sequentially form a base coating, a thermal recording layer, and a protective layer. The resulting product is then over-calendered to smooth the surface, thus obtaining a thermal recorder.

[0161] (Example 2)

[0162] Except that calcium carbonate (trade name: Brilliant-15, manufactured by Shiraishi Kogyo Kaisha, Ltd.) was used instead of aluminum hydroxide in the preparation of the coating for the thermal recording layer, the thermal recorder was obtained in the same manner as in Example 1.

[0163] (Example 3)

[0164] Except that clay (trade name: Hydragloss 90, manufactured by KaMin LLC) was used instead of aluminum hydroxide in the preparation of the coating for the thermal recording layer, the thermal recorder was obtained in the same manner as in Example 1.

[0165] (Example 4)

[0166] Except that in the preparation of the coating for the base layer, the amount of hollow particles A is 46.7 parts instead of 100 parts, the amount of calcined kaolin is 46.0 parts instead of 38.0 parts, and the amount of water is 145 parts instead of 100 parts, the thermal recorder is obtained in the same manner as in Example 1.

[0167] (Example 5)

[0168] Except that latex B was used instead of latex A in the preparation of the base coat coating, the thermal recorder was obtained in the same manner as in Example 1.

[0169] (Example 6)

[0170] Except that latex C was used instead of latex A in the preparation of the base coat coating, the thermal recorder was obtained in the same manner as in Example 1.

[0171] (Example 7)

[0172] Except that hollow particles B were used instead of hollow particles A in the preparation of the primer coating, the thermal recorder was obtained in the same manner as in Example 1.

[0173] (Example 8)

[0174] Except that in the preparation of the coating for the thermal recording layer, the amount of liquid C was 45.5 parts instead of 22.7 parts, the amount of aluminum hydroxide was 22 parts instead of 32 parts, and the amount of water was 190 parts instead of 200 parts, the thermal recorder was obtained in the same manner as in Example 1.

[0175] (Example 9)

[0176] Preparation of colorimetric reagent dispersion (liquid D)

[0177] 40 parts of 4,4'-bis(3-tolylureo)diphenylmethane, 40 parts of a 10% aqueous solution of polyvinyl alcohol (degree of polymerization: 500; degree of saponification: 88%), and 20 parts of water were mixed. The resulting mixture was pulverized using a sand mill (manufactured by Imex Co., Ltd.) to an average particle size of 1.0 μm to obtain a color developer dispersion (liquid D).

[0178] Except that in the preparation of the coating for the thermal recording layer, 22.7 parts of liquid D were added, 22 parts of aluminum hydroxide were used instead of 32 parts, and 180 parts of water were used instead of 200 parts, the thermal recorder was obtained in the same manner as in Example 1.

[0179] (Example 10)

[0180] Preparation of colorimetric reagent dispersion (liquid E)

[0181] 40 parts of a urea-carbamate compound represented by formula (2), 40 parts of a 10% aqueous solution of polyvinyl alcohol (degree of polymerization: 500; degree of saponification: 88%), and 20 parts of water were mixed. The resulting mixture was pulverized using a sand mill (manufactured by Imex Co., Ltd.) to an average particle size of 1.0 μm to obtain a color developer dispersion (liquid E).

[0182] Except that in the preparation of the coating for the thermal recording layer, 22.7 parts of liquid E, 22 parts of aluminum hydroxide instead of 32 parts, and 180 parts of water instead of 200 parts were further added, the thermal recorder was obtained in the same manner as in Example 1.

[0183] (Example 11)

[0184] Preparation of colorimetric reagent dispersion (liquid F)

[0185] 40 parts of the crosslinked diphenyl sulfone compound represented by formula (3), 40 parts of a 10% aqueous solution of polyvinyl alcohol (degree of polymerization: 500; degree of saponification: 88%), and 20 parts of water were mixed. The resulting mixture was pulverized using a sand mill (manufactured by Imex Co., Ltd.) to an average particle size of 1.0 μm to obtain a color developer dispersion (liquid F).

[0186] Except that in the preparation of the coating for the thermal recording layer, 22.7 parts of liquid F, 22 parts of aluminum hydroxide instead of 32 parts, and 180 parts of water instead of 200 parts were further added, the thermal recorder was obtained in the same manner as in Example 1.

[0187] (Example 12)

[0188] Except that in the preparation of the coating for the thermal recording layer, the amount of liquid C was 0 parts instead of 22.7 parts, the amount of aluminum hydroxide was 42 parts instead of 32 parts, and the amount of water was 210 parts instead of 200 parts, the thermal recorder was obtained in the same manner as in Example 1.

[0189] (Example 13)

[0190] Except that in the preparation of the base coat coating, the amount of calcined kaolin was 66 parts instead of 38 parts, 20.8 parts of latex C was used instead of 79.2 parts of latex A, 56.6 parts of hollow particles C was used instead of 100 parts of hollow particles A, and the amount of water was 175 parts instead of 100 parts, the thermal recorder was obtained in the same manner as in Example 1.

[0191] (Example 14)

[0192] Except that in the preparation of the primer coating, hollow particles C are used instead of hollow particles A, 50 parts of calcined kaolin are used instead of 38 parts, 25 parts of latex C are used instead of 79.2 parts of latex A, 20 parts of 25% oxidized starch solution are used instead of 32 parts, and 130 parts of water are used instead of 100 parts, the primer coating is obtained in the same manner as in Example 1.

[0193] Except that in the preparation of the coating for the thermal recording layer, the amount of liquid A is 36.7 parts instead of 31.8 parts, the amount of liquid B is 73.3 parts instead of 63.6 parts, the amount of liquid C is 55 parts instead of 22.7 parts, the amount of 15% fully saponified polyvinyl alcohol aqueous solution is 66.7 parts instead of 46.7 parts, the amount of aluminum hydroxide is 27 parts instead of 32 parts, 10 parts of amorphous silica (trade name: Nipsil E-743, manufactured by Tosoh Silica Corporation) is further added, and the amount of water is 140 parts instead of 200 parts, the coating for the thermal recording layer is obtained in the same manner as in Example 1.

[0194] Except for using the above-described base coating and thermal recording layer coating, the thermal recording body of Example 14 was obtained in the same manner as in Example 1.

[0195] (Comparative Example 1)

[0196] Except that in the preparation of the coating for the thermal recording layer, amorphous silica (trade name: Nipsil E743, manufactured by Tosoh Silica Corporation) was used instead of aluminum hydroxide, the thermal recorder was obtained in the same manner as in Example 1.

[0197] The thermal recorder obtained in this way was evaluated for the following properties. The results are shown in Table 1.

[0198] [Record Concentration]

[0199] Images were recorded on each thermal recorder using a thermal recording tester (trade name: TH-PMD, manufactured by Ohkura Electric Co., Ltd.) with applied energies of 0.17 mJ / point (medium energy range) and 0.25 mJ / point (high energy range). The reflectance concentration of the recorded portions was measured using a spectrophotometer (X-Rite 504, manufactured by X-Rite).

[0200] [Plasticizer Resistance]

[0201] A wrapping film (trade name: Hi-S Soft, manufactured by Nippon Carbide Industries Co., Inc.) was wrapped three times around a polycarbonate tube (diameter: 40 mm), and samples of each thermal recorder, which had been developed using a label printer (trade name: L-2000, manufactured by Ishida Co., Ltd.), were placed on the film. The wrapping film was then wrapped three more times around the samples, and the samples were treated by placing them at 40°C for 24 hours. Before and after this treatment, the reflectance concentration of the recording portion was measured using a spectrophotometer (X-Rite 504, manufactured by X-Rite). Furthermore, the residual percentage of the recording portion was calculated using the following equation: Residual percentage (%) = (Recording concentration after treatment / Recording concentration before treatment) × 100

[0202] [Water-resistant plasticizer properties]

[0203] A wrapping film (trade name: Hi-S Soft, manufactured by Nippon Carbide Industries Co., Inc.) was wrapped three times around a polycarbonate tube (diameter: 40 mm). Samples obtained by immersing each thermal recorder (developed using a label printer, trade name: L-2000, manufactured by Ishida Co., Ltd.) in water for 5 seconds were placed on the film. The wrapping film was then wrapped three more times around the sample, and the sample was treated at 40°C for 24 hours. Before and after this treatment, the reflectance concentration of the recording portion was measured using a spectrophotometer (X-Rite 504, manufactured by X-Rite). Furthermore, the residual percentage of the recording portion was calculated according to the following equation.

[0204] Residual percentage (%) = (Record concentration after treatment / Record concentration before treatment) × 100

[0205] [Alcohol resistance]

[0206] Samples of each thermal recorder, which had already been developed using a label printer (trade name: L-2000, manufactured by Ishida Co., Ltd.), were immersed in a 75% (v / v) aqueous ethanol solution for 10 minutes and 30 minutes, respectively. Before and after this treatment, the reflectance concentration of the recording portion was measured using a spectrophotometer (X-Rite 504, manufactured by X-Rite). Furthermore, the residual percentage of the recording portion was calculated using the following equation: Residual percentage (%) = (Recording concentration after treatment / Recording concentration before treatment) × 100

[0207] Table 1

[0208]

[0209] Industrial availability

[0210] The thermal recorder of the present invention is excellent in terms of resistance to plasticizers, water plasticizers and alcohols, and fully meets the requirements for improved performance of thermal recorders. For example, even when the thermal recorder comes into contact with alcohol, it does not show color in blank paper portions and does not fade in printed portions.

Claims

1. A thermal recording device, comprising a base coating layer and a thermal recording layer sequentially on a support. The base coating comprises hollow particles, a binder, and inorganic pigment I. The thermal recording layer comprises a leuco dye, a color developer, and inorganic pigment II, and The thermal recording layer comprises an N,N'-diarylurea compound represented by formula (1) as a color developer, and an inorganic pigment II with an oil absorption of less than 130 ml / 100 g. R2 can be the same or different, and each represents C. 1-12 Alkyl, C 7-12 Aryl or C 6-12 Aryl group, and the aralkyl group and the aryl group can each be C-terminated. 1-12 Alkyl, C 1-12 Alkoxy, C 6-12 Aryl or halogen substitution; A1 can be the same or different, and each represents hydrogen or C. 1-4 alkyl, in, The thermal recording layer further comprises 4,4'-bis(3-tolylureo)diphenylmethane as a second colorimetric agent, and The content of inorganic pigment I is based on the total solid content of the base coating being less than 50% by mass.

2. The thermal recorder according to claim 1, wherein, The inorganic pigment I has an oil absorption capacity of less than 130 ml / 100 g.

3. The thermal recorder according to claim 1 or 2, wherein the inorganic pigment II is at least one selected from the group consisting of calcium carbonate, aluminum hydroxide and clay.

4. The thermal recorder according to claim 1 or 2, wherein, The hollow particles have a maximum particle size (D100) of 10–40 μm, an average particle size (D50) of 4.0–15 μm, a ratio of the maximum particle size (D100) to the average particle size (D50) of 1.8–3.0, and the volume percentage of particles with a particle size of 2.0 μm or less is less than 1%.

5. The thermal recorder according to claim 1 or 2, wherein, The hollowness of the hollow particles is 80-98%.

6. The thermal recorder according to claim 1 or 2, wherein the undercoat comprises an adhesive having a glass transition temperature below -10°C.

7. The thermal recorder according to claim 1 or 2, wherein, The thermal recording layer further comprises, as a second colorimetric agent, at least one selected from the group consisting of a urea-carbamate compound represented by formula (2) and a cross-linked diphenyl sulfone compound represented by formula (3). Where n represents an integer from 1 to 6.

8. The thermal recorder according to claim 7, wherein, The content of the second color developer is 0.2 to 3 parts by mass relative to 1 part by mass of the leuco dye.

9. The thermal recorder according to claim 1 or 2, wherein the N,N'-diarylurea compound represented by formula (1) is selected from N,N'-di-[3-(p-toluenesulfonyloxy)phenyl]urea, N,N'-di-[3-(o-toluenesulfonyloxy)phenyl]urea, N,N'-di-[3-(benzenesulfonyloxy)phenyl]urea, N,N'-di-[3-(tris(toluenesulfonyloxy)phenyl]urea, N,N'-di-[3-(4-ethylbenzenesulfonyloxy)phenyl]urea, N,N'-di-[3-(2-naphthalenesulfonyloxy)phenyl]urea, N,N'-di At least one of the following groups: -[3-(p-methoxybenzenesulfonyloxy)phenyl]urea, N,N'-di-[3-(benzylsulfonyloxy)phenyl]urea, N,N'-di-[3-(ethanesulfonyloxy)phenyl]urea, N,N'-di-[3-(p-toluenesulfonyloxy)-4-methyl-phenyl]urea, N,N'-di-[4-(p-toluenesulfonyloxy)phenyl]urea, N,N'-di-[4-(benzenesulfonyloxy)phenyl]urea, N,N'-di-[4-(ethanesulfonyloxy)phenyl]urea, and N,N'-di-[2-(p-toluenesulfonyloxy)phenyl]urea.

10. The thermal recorder according to claim 1 or 2, wherein, The thermal recorder has an adhesive layer on at least one surface of the support.

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