Thermosensitive recording body

Abstract

Disclosed is a heat-sensitive recording body which has at least a primer layer containing hollow particles, a binder, and inorganic pigment I; a heat-sensitive recording layer containing a leuco dye and a color developer, in the order described below on a support, (A) the heat-sensitive recording body contains 5-(N-3-methylphenyl-sulfonamide)-N',N"-bis-(3-methylphenyl) isophthalic acid diamide as a preservability improver, or (B) the heat-sensitive recording body contains 5-(N-3-methylphenyl-sulfonamide)-N',N"-bis-(3-methylphenyl) isophthalic acid diamide as a color developer, and contains a pigment having an oil absorption amount of 130 ml / 100 g or less as inorganic pigment II.

Description

Technical Field

[0001] This invention relates to a thermal recorder that utilizes a colorimetric reaction between a leuco dye and a colorimetric agent. Background Technology

[0002] Thermal recorders, widely used in practical applications, 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 include, for example, the ability to form color images solely through the application of heat, and further, 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 scientific research equipment.

[0003] Because this color development reaction is reversible, it is known that color images will 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, alcohol disinfection and sterilization have become common practices 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 and 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 that exhibits excellent resistance to water-plasticizers and water in the recording section, and excellent resistance to alcohol in both the recording section and the background section.

[0010] In another embodiment of the invention, the main objective is to provide a thermal recorder that exhibits excellent resistance to alcohols and plasticizers in the recording section, as well as excellent resistance to thermal background fogging.

[0011] Solution for solving the problem

[0012] In view of the existing technology, the inventors conducted in-depth research and discovered a solution to this problem. More specifically, the present invention provides the following thermal recording medium.

[0013] Project 1.

[0014] A thermal recorder, comprising at least an undercoat layer and a thermal recording layer sequentially on a support.

[0015] The base coat consists of hollow particles, a binder, and inorganic pigment I.

[0016] The thermal recording layer contains leuco dyes and developers.

[0017] in

[0018] (A) The thermal recording layer contains 5-(N-3-methylphenyl-sulfonamide)-N′,N″-bis-(3-methylphenyl)-isophthalic acid diamide as a preservation improver, or

[0019] (B) The thermal recording layer contains 5-(N-3-methylphenyl-sulfonamide)-N′,N″-bis-(3-methylphenyl)-isophthalic acid diamide as a color developer, and contains an inorganic pigment II with an oil absorption of less than 130 mL / 100 g.

[0020] Project 2.

[0021] According to the thermal recorder of Project 1, wherein (A) the thermal recording layer contains 5-(N-3-methylphenyl-sulfonamide)-N′,N″-bis-(3-methylphenyl)-isophthalic acid diamide as a preservation improver.

[0022] Project 3.

[0023] According to the thermal recorder described in Project 2, the colorimetric agent is a diphenyl sulfone derivative represented by the following formula (1):

[0024]

[0025] Where R 1 and R 2 Same or different, and indicates C 1-4 Alkyl, C 2-4 alkenyl, C 1-4Alkoxy, C 2-4 alkenyloxy group, C 7-12 Arylalkyloxy or halogen atom, m represents an integer from 0 to 2, n represents an integer from 1 to 3, p and q are the same or different and represent integers from 0 to 2.

[0026] Project 4.

[0027] According to the thermal recorder of Project 3, the diphenyl sulfone derivative represented by formula (1) is at least one selected from the group consisting of 4-hydroxy-4′-isopropoxydiphenyl sulfone, 4,4′-dihydroxydiphenyl sulfone, 2,4′-dihydroxydiphenyl sulfone, bis(3-allyl-4-hydroxy)diphenyl sulfone, 4-hydroxyphenyl(4′-propoxyphenyl) sulfone, 4-allyloxy-4′-hydroxydiphenyl sulfone and 4-hydroxy-4′-benzyloxydiphenyl sulfone.

[0028] Project 5.

[0029] According to the thermal recorder described in Project 2, the colorimetric agent is N-p-toluenesulfonyl-N′-3-(p-toluenesulfonyloxy)phenylurea.

[0030] Project 6.

[0031] According to the thermal recorder described in Project 2, the colorimetric agent is N-[2-(3-phenylureid)phenyl]benzenesulfonamide.

[0032] Project 7.

[0033] The thermal recorder according to any one of items 2 to 6, wherein the content of the preservation improver is 0.1 to 4 parts by mass relative to 1 part by mass of the colorimetric agent.

[0034] Project 8.

[0035] According to the thermal recorder described in Project 1, wherein (B) the thermal recording layer comprises 5-(N-3-methylphenyl-sulfonamide)-N′,N″-bis-(3-methylphenyl)-isophthalic acid diamide as a color developer and an inorganic pigment II with an oil absorption of less than 130 ml / 100 g.

[0036] Project 9.

[0037] The thermal recorder according to Project 8 includes a pigment as inorganic pigment II with an oil absorption of less than 65 ml / 100 g.

[0038] Project 10.

[0039] The thermal recorder according to item 8 or 9 includes at least one inorganic pigment II selected from the group consisting of calcium carbonate, aluminum hydroxide and clay.

[0040] Project 11.

[0041] The thermal recorder according to any one of items 8 to 10 includes a pigment as inorganic pigment I with an oil absorption of 130 mL / 100 g or less.

[0042] Project 12.

[0043] The thermal recorder according to any one of items 8 to 11 includes at least one inorganic pigment selected from the group consisting of calcium carbonate, aluminum hydroxide and clay.

[0044] Project 13.

[0045] According to any one of items 8 to 12, the content of inorganic pigment I is less than 50 parts by mass based on the total solid content of the base coating.

[0046] Project 14.

[0047] The thermal recorder according to any one of items 8 to 13, wherein the thermal recording layer comprises at least one selected from the group consisting of the following as a second colorimetric agent:

[0048] Urea urethane compound represented by the following formula (2):

[0049]

[0050] Crosslinked diphenyl sulfone compounds represented by the following formula (3):

[0051]

[0052] Where r represents an integer from 1 to 6,

[0053] N,N′-diarylurea compounds represented by the following formula (4):

[0054]

[0055] Where R 3 C represents 1-12 Alkyl, C 7-12 Aryl or C 6-12 Aryl group, wherein the aralkyl group and the aryl group may optionally be C 1-12 Alkyl, C 1-12 Alkoxy, C 6-12 Aryl or halogen atom substitution, multiple R 3They can be the same or different, A 1 Represents a hydrogen atom or C 1-4 Alkyl groups, and multiple A groups 1 They can be the same or different.

[0056] Compounds represented by the following formula (5):

[0057]

[0058] Where R 4 To R 8 Same or different, and representing hydrogen atom, halogen atom, nitro, amino, alkyl, alkoxy, aryloxy, alkylcarbonyloxy, arylcarbonyloxy, alkylcarbonylamino, arylcarbonylamino, alkylsulfonylamino, arylsulfonylamino, monoalkylamino, dialkylamino, or arylamino, and

[0059] 4,4′-Bis(3-Tolylureo)diphenylmethane.

[0060] Project 15.

[0061] According to the thermal recorder described in Project 14, it includes a second colorimetric agent in an amount of 0.2 to 3 parts by mass based on 1 part by mass of leuco dye.

[0062] Project 16.

[0063] The thermal recorder according to any one of items 1 to 15

[0064] in

[0065] The maximum particle size (D100) of the hollow particles is 10–30 μm and the average particle size (D50) is 4.0–15 μm. The ratio of the maximum particle size (D100) to the average particle size (D50), D100 / D50, is 1.8–3.0.

[0066] The volume percentage of particles with a diameter of less than 2.0 μm is less than 1%.

[0067] Project 17.

[0068] The thermal recorder according to any one of items 1 to 16, wherein the hollowness of the hollow particles is 80 to 98%.

[0069] Project 18.

[0070] The thermal recorder according to any one of items 1 to 17, wherein the binder in the undercoat comprises a binder resin having a glass transition temperature of -10°C or less.

[0071] Project 19.

[0072] The thermal recorder according to any one of items 1 to 17, wherein the binder in the undercoat comprises a binder resin having a glass transition temperature of -30°C or less.

[0073] Project 20.

[0074] The thermal recorder according to any one of items 1 to 19 further includes an adhesive layer on at least one surface of the support.

[0075] The effects of the invention

[0076] The thermal recorder of the present invention exhibits excellent resistance to water plasticizers and water resistance in the recording section, and excellent resistance to alcohol in both the recording section and the background section.

[0077] In another embodiment of the present invention, the thermal recorder exhibits excellent resistance to alcohols and plasticizers in the recording section, and excellent resistance to heat-induced background fogging. The thermal recorder can also improve color density. Detailed Implementation

[0078] In this specification, the terms "comprising" or "including" include the following concepts: including, substantially consisting of, and composed of.

[0079] 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.

[0080] As used in this article, “latex” includes latex in the form of a gel or dry film formed by drying the dispersion medium.

[0081] In this invention, the average particle size refers to the median size based on volume, as measured by laser diffraction. More simply, the average particle size can be represented by the average of ten particles determined by measuring the particle size in a particle image (SEM image) using an electron microscope.

[0082] This invention relates to a thermal recorder, which comprises at least a base coating and a thermal recording layer sequentially on a support.

[0083] The base coat consists of hollow particles, a binder, and inorganic pigment I.

[0084] The thermal recording layer contains leuco dyes and developers.

[0085] in

[0086] (A) The thermal recording layer contains 5-(N-3-methylphenyl-sulfonamide)-N′,N″-bis-(3-methylphenyl)-isophthalic acid diamide as a preservation improver, or

[0087] (B) The thermal recording layer contains 5-(N-3-methylphenyl-sulfonamide)-N′,N″-bis-(3-methylphenyl)-isophthalic acid diamide as a color developer, and contains an inorganic pigment II with an oil absorption of less than 130 mL / 100 g.

[0088] The thermal recorder having feature (A) and the thermal recorder having feature (B) are referred to as thermal recorder (A) and thermal recorder (B), respectively, and are described in detail below.

[0089] A. Thermal recording medium (A)

[0090] In this invention, the thermal recording medium includes a base coating layer comprising hollow particles, a binder, and inorganic pigment I on a support, and a thermal recording layer comprising a leuco dye, a developer, and a binder on the base coating layer, wherein the thermal recording layer comprises 5-(N-3-methylphenyl-sulfonamide)-N′,N″-bis-(3-methylphenyl)-isophthalic acid diamide as a preservation improver.

[0091] support body

[0092] The support in this invention is not particularly limited in terms of 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 20–200 μm. The density of the support is not particularly limited, preferably about 0.60–0.85 g / cm³. 3 .

[0093] base coat

[0094] 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.

[0095] hollow particles

[0096] From the viewpoint of enhancing buffering, the hollow particles are preferably formed of organic resin. The undercoat containing hollow particles and therefore having excellent thermal insulation properties can prevent heat diffusion applied to the thermal recording layer and increase the sensitivity of the thermal recorder.

[0097] 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.

[0098] 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 relatively large average particle sizes can also be produced through an alkaline swelling treatment of core-shell particles in which alkaline-swellable core particles are coated with a non-alkaline-swellable shell.

[0099] 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.

[0100] 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 with an undercoat layer having excellent thermal insulation properties, 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 that excel in improving the thermal insulation properties of the undercoat layer are preferred.

[0101] 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.

[0102] The maximum particle size of the hollow particles in this invention is preferably 10–30 μm, more preferably 10–25 μm, and even more preferably 10–20 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 30 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 in the image are less likely to occur can be obtained.

[0103] The average particle size of the hollow particles in this invention is preferably 4.0 to 15 μm, and more preferably 4.5 to 15 μm. The average particle size used here is the diameter at which the volume of the larger particle equals 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.

[0104] 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.

[0105] 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 hollowness ratio can be high, and the thermal insulation of the undercoating 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 undercoating and suppresses white spots in the image.

[0106] In the particle size distribution, the volume percentage of hollow particles with a particle size of 2.0 μm or less is preferably 1% or less. The particle size distribution can be determined using a laser diffraction particle size distribution analyzer. The particle size distribution can also be determined by measuring the particle size in a particle image (SEM image) using an electron microscope. It is also preferred that the volume percentage of hollow particles with a particle size of 2.0 μm or less is 0.5% or less, and more preferably, hollow particles with a particle size of 2.0 μm or less are not included. Hollow particles with a particle size of 2 μm or less are considered to contribute very little to thermal insulation because they are too small to have sufficient hollow area. When the volume percentage of hollow particles with a particle size of 2 μm or less in the undercoat is 1% or less, the recording density, image quality, etc., can be improved.

[0107] 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 undercoat containing the hollow particles can be imparted with excellent thermal insulation properties. This improves the recording concentration of the preferred color developer described below, while allowing the preservation improver effect of the present invention to be fully realized simultaneously. When the hollowness of the hollow particles is 98% or less, the strength of the film around the hollow portion is improved, thus hollow particles that do not collapse even when the undercoat is formed can be obtained.

[0108] The hollowness of the hollow particles is measured by measuring the true specific gravity according to the IPA method, and the true specific gravity value is used as follows.

[0109] (1) Sample pretreatment

[0110] The sample was dried at 60°C for 24 hours.

[0111] (2) Reagents

[0112] Isopropanol (IPA: Ultrapure Reagent)

[0113] (3) Measurement method

[0114] - Weighing volumetric flask (W1).

[0115] Weigh approximately 0.5 g of the dried sample (W2) into a volumetric flask.

[0116] Add approximately 50 mg of IPA and shake the volumetric flask thoroughly to completely remove any air from the capsule.

[0117] - Add IPA to the mark line and weigh the volumetric flask (W3).

[0118] - As a blank, add IPA separately to the mark line of the volumetric flask and weigh the volumetric flask (W4).

[0119] (4) Calculation of true specific gravity

[0120] True specific gravity = {(W2-W1)×((W4-W1) / 100)} / {(W4-W1)-(W3-W2)}

[0121] (5) Calculation of hollow ratio

[0122] Hollow content (%) = {1 - 1 / (1.1 / true specific gravity)} × 100

[0123] 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.

[0124] 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.

[0125] adhesive

[0126] 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, ethyl cellulose and carboxymethyl 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.

[0127] The adhesive preferably comprises an adhesive resin with a glass transition temperature (Tg) 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 because image quality can be further improved in the low energy range. A glass transition temperature below -50°C is undesirable because adhesion will occur. Therefore, a glass transition temperature above -40°C is preferred.

[0128] Inorganic Pigment I

[0129] The base coating of this invention comprises inorganic pigment I. From the viewpoint of increasing recording concentration and improving water resistance, plasticizer resistance, and alcohol resistance, the oil absorption of inorganic pigment I is preferably 150 ml / 100g or less, more preferably 130 ml / 100g or less, and even more preferably 125 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 further preferably 50 ml / 100g or more, more preferably 70 ml / 100g or more, and even more preferably 80 ml / 100g or more. The oil absorption is a value measured according to the method of JIS K 5101.

[0130] Various inorganic pigments can be used as inorganic pigment I, and specific examples include calcined kaolin, amorphous silica, light calcium carbonate, talc, kaolin, and clay. The average particle size of the primary particles of these inorganic pigments I is preferably about 0.01 to 5 μm, and more preferably about 0.02 to 3 μm. 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.

[0131] 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 And even more preferably about 3 to 8 g / m 2 .

[0132] thermal recording layer

[0133] Leuco dyes

[0134] 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.

[0135] 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.

[0136] 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 30% by mass or less can improve the heat resistance.

[0137] color developer

[0138] Specific examples of color developers 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, 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-methoxybenzyl)-phenylene oxide, etc. [3-[3-(p-toluenesulfonyl)propoxy]salicylic acid, 5-[p-(2-p-methoxyphenoxyethoxy]cumyl]salicylic acid, and 4-{3-(p-toluenesulfonyl)propoxy]salicylic acid zinc; 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 containing -SO₂NH₄ bonds in their molecules, 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. Colorimetric reagents are not limited to these, and may, when necessary, be a combination of two or more compounds.

[0139] In this invention, the color developer is preferably a diphenyl sulfone derivative represented by formula (1). This allows for the full realization of the effects of this invention.

[0140]

[0141] Where R 1 and R 2 Same or different, and indicates C 1-4 Alkyl, C 2-4 alkenyl, C 1-4 Alkoxy, C 2-4 alkenyloxy group, C 7-12 Arylalkyloxy or halogen atom, m represents an integer from 0 to 2, n represents an integer from 1 to 3, p and q are the same or different and represent integers from 0 to 2.

[0142] In equation (1), R 1 or R 2 C 1-4 Alkyl groups can be straight-chain or branched, examples of which include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, and tert-butyl. Alkyl groups used herein also include C10. 1-4 The alkyl moiety of the alkoxy group. C 2-4 Alkenes can be linear or branched, examples of which include vinyl, n-propenyl (allyl), and n-butenyl. Alkenes used herein also include C... 2-4 The alkenyl moiety of the alkoxy group. Arylalkyl refers to arylalkyl, C 7-12 Examples of aralkyl groups include benzyl, 1-phenylethyl, 2-phenylethyl, and 3-phenylpropyl. Halogen atoms include fluorine, chlorine, bromine, and iodine. If multiple R groups are present... 1 and / or R 2 Then they can be the same or different.

[0143] R 1 R 2 There are no particular restrictions on the substitution position of OH, but the 3-position, 4-position or 5-position is preferred.

[0144] m is preferably 0 or 1, n is preferably 1, and p and q are preferably the same or different and are 0 or 1.

[0145] The diphenyl sulfone derivative represented by formula (1) is not particularly limited, but is preferably selected from at least one of the group consisting of 4-hydroxy-4′-isopropoxydiphenyl sulfone, 4,4′-dihydroxydiphenyl sulfone, 2,4′-dihydroxydiphenyl sulfone, bis(3-allyl-4-hydroxy)diphenyl sulfone, 4-hydroxyphenyl(4′-n-propoxyphenyl) sulfone, 4-allyloxy-4′-hydroxydiphenyl sulfone and 4-hydroxy-4′-benzyloxydiphenyl sulfone.

[0146] In this invention, the color developer is preferably N-p-toluenesulfonyl-N′-3-(p-toluenesulfonyloxy)phenylurea. This allows for the full realization of the effects of this invention.

[0147] In this invention, the color developer is preferably N-[2-(3-phenylureo)phenyl]benzenesulfonamide. This allows for the full realization of the effects of this invention.

[0148] The content of the developer is not particularly limited and can be adjusted according to the leuco dye used. Typically, the content of the developer based on 1 part by weight of leuco dye is preferably 0.5 parts by weight or more, more preferably 0.8 parts by weight or more, even more preferably 1 part by weight or more, even more preferably 1.2 parts by weight or more, and particularly preferably 1.5 parts by weight or more. The content of the developer based on 1 part by weight of leuco dye is also preferably 10 parts by weight or less, more preferably 5 parts by weight or less, even more preferably 4 parts by weight or less, and particularly preferably 3.5 parts by weight or less. A developer content of 0.5 parts by weight or more can improve recording performance, while a content of 10 parts by weight or less can effectively reduce background fogging in high-temperature environments.

[0149] The thermal recording layer of the present invention contains 5-(N-3-methylphenyl-sulfonamide)-N′,N″-bis-(3-methylphenyl)-isophthalic acid diamide as a preservation improver. Therefore, the thermal recorder of the present invention has excellent water plasticizer resistance and water resistance in the recording section, and excellent alcohol resistance in both the recording section and the background section.

[0150] The content of 5-(N-3-methylphenyl-sulfonamide)-N′,N″-bis-(3-methylphenyl)-isophthalic acid diamide as a preservation improver is not particularly limited and can be adjusted according to the colorimetric agent used. Typically, the content of 5-(N-3-methylphenyl-sulfonamide)-N′,N″-bis-(3-methylphenyl)-isophthalic acid diamide is preferably about 0.1 to 4 parts by weight based on 1 part by weight of colorimetric agent, more preferably about 0.10 to 3 parts by weight, even more preferably about 0.10 to 2 parts by weight, even more preferably about 0.15 to 1 part by weight, and particularly preferably about 0.15 to 1.0 parts by weight. A content of 0.1 parts by weight or more can improve the water resistance and plasticizing properties of the recording section, as well as the alcohol resistance of the recording section, while a content of 4 parts by weight or less can increase the recording concentration.

[0151] In this invention, it is preferred that the following compounds are not present as preservation improvers: urea carbamate compounds represented by formula (2), such as 4,4′-bis[(4-methyl-3-phenoxycarbonylaminophenyl)ureo]diphenyl sulfone, 4,4′-bis[(2-methyl-5-phenoxycarbonylaminophenyl)ureo]diphenyl sulfone and 4-(2-methyl-3-phenoxycarbonylaminophenyl)ureo-4′-(4-methyl-5-phenoxycarbonylaminophenyl)ureo diphenyl sulfone, and crosslinked diphenyl sulfone compounds represented by formula (3).

[0152]

[0153] (where r represents an integer from 1 to 6).

[0154] Optionally, without impairing the effects of the 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.

[0155] 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.

[0156] 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 about 2-25% by mass, more preferably about 5-20% by mass, and even more preferably about 5-15% by mass, based on the total solid content of the thermal recording layer.

[0157] As other components constituting the thermal recording layer, binders can be used. Additionally, additives such as pigments, crosslinking agents, waxes, metal soaps, water resistance improvers, dispersants, colored dyes, and fluorescent dyes can be used as needed.

[0158] Examples of binders include water-soluble polymers such as polyvinyl alcohol and its derivatives, starch and its derivatives, cellulose derivatives such as hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, methylcellulose and ethylcellulose, 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.

[0159] 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 10% by mass based on the total solid content of the thermal recording layer, and more preferably about 2 to 8% by mass or about 1 to 5% by mass.

[0160] The thermal recording layer is formed on the base layer as follows: For example, by 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, a color developer, and a preservation improver, along with, as needed, a sensitizer and stabilizer, either 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 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, about 2 to 10 g / m 2Even more preferably, it is about 2.5 to 8 g / m³. 2 And particularly preferred is about 3 to 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.

[0161] protective layer

[0162] 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.

[0163] 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, heavy calcium carbonate, calcined kaolin, titanium dioxide, magnesium carbonate, aluminum hydroxide, colloidal silica, and synthetic layered mica; and plastic pigments such as urea-formalin resin fillers; etc. The pigment content is preferably about 20 to 80% by mass, and more preferably about 30 to 75% by mass, based on the total solid content of the protective layer.

[0164] The binder included in the protective layer is not particularly limited, and an aqueous binder selected from water-soluble and water-dispersible binders can be used. The binder can be suitably selected from binders suitable for thermal recording layers. In particular, polyvinyl alcohol or modified polyvinyl alcohol is preferred from the viewpoint of enhancing the binding effect on pigments and the preservation of the recording section against plasticizers and solvents such as oils; especially modified polyvinyl alcohol, such as acetyl-modified polyvinyl alcohol, carboxyl-modified polyvinyl alcohol, and diacetone-modified polyvinyl alcohol, is more preferred. The binder content, based on the total solid content of the protective layer, is preferably about 10 to 70% by mass, and more preferably about 20 to 50% by mass.

[0165] 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 amount of the protective layer coating applied, but it is preferably about 0.3 to 15 g / m³ 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. 2Depending 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.

[0166] Other layers

[0167] 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. 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 release layer containing silicone on a protective layer and applying an adhesive on one side.

[0168] thermal recording device

[0169] Thermal recorders can be produced 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, bar coating, curtain coating, groove coating, slip coating, and extrusion, can be used to form these 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.

[0170] B. Thermal recording medium (B)

[0171] In this invention, the thermal recorder comprises, in sequence on a support, at least a base layer containing hollow particles, a binder, and inorganic pigment I, and a thermal recording layer containing a leuco dye, a color developer, and inorganic pigment II. The thermal recording layer contains 5-(N-3-methylphenyl-sulfonamide)-N′,N″-bis-(3-methylphenyl)-isophthalic acid diamide as a color developer, and contains an inorganic pigment II with an oil absorption of less than 130 mL / 100 g.

[0172] Support body

[0173] The support used in this embodiment may be those described in the support section of A. Thermal Recorder (A) above.

[0174] base coat

[0175] The thermal recorder of the present invention includes an undercoat layer between a support and a thermal recording layer, the undercoat layer comprising hollow particles, a binder, and an inorganic pigment I.

[0176] hollow particles

[0177] The hollow particles used can be those described in the undercoat portion of A. thermal recorder (A) above, and the content of hollow particles can be set as described in the undercoat portion of A. thermal recorder (A) above.

[0178] adhesive

[0179] The adhesive used may be those described in the undercoat section of A. thermal recorder (A) above, and the content of the adhesive may be set as described in the undercoat section of A. thermal recorder (A) above.

[0180] Inorganic Pigment I

[0181] The base coating layer of this invention comprises inorganic pigment I. From the viewpoint of improving recording concentration and enhancing alcohol resistance and plasticizer resistance, the base coating layer preferably comprises a pigment, as inorganic pigment I, with an oil absorption of 130 ml / 100 g or less. More preferably, the oil absorption of inorganic pigment I is 125 ml / 100 g or less, and even more preferably 110 ml / 100 g 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 40 ml / 100 g or more, and even more preferably 80 ml / 100 g or more. The oil absorption is a value obtained according to the method of JIS K 5101.

[0182] Various inorganic pigments can be used as inorganic pigment I. Specific examples include, for example, calcium carbonate such as light calcium carbonate, aluminum hydroxide, clay such as calcined kaolin and kaolin, talc, and other inorganic pigments. Inorganic pigment I is preferably at least one selected from the group consisting of calcium carbonate, aluminum hydroxide, and clay. From the viewpoint of improving color sensitivity, the content of inorganic pigment I based on the total solid 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 solid content of the undercoat is also preferably 20% by mass or more, and more preferably 25% by mass or more.

[0183] 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 .

[0184] thermal recording layer

[0185] Leuco dyes

[0186] The thermal recording layer of the thermal recorder of the present invention may contain any of a variety of known colorless or light-colored leuco dyes. The leuco dye used may be any of the leuco dyes described in the thermal recording layer section of A. Thermal Recorder (A) above. The content of the leuco dye may be set as described in the thermal recording layer section of A. Thermal Recorder (A) above.

[0187] color developer

[0188] In this invention, the thermal recording layer contains 5-(N-3-methylphenyl-sulfonamide)-N′,N″-bis-(3-methylphenyl)-isophthalic acid diamide as a color developer. The combination of this compound with inorganic pigment II can bring excellent alcohol resistance and plasticizer resistance in the recording layer, as well as excellent resistance to heat background fogging.

[0189] The content of 5-(N-3-methylphenyl-sulfonamide)-N′,N″-bis-(3-methylphenyl)-isophthalic acid diamide is not particularly limited and can be adjusted according to the leuco dye used. Typically, the content of 5-(N-3-methylphenyl-sulfonamide)-N′,N″-bis-(3-methylphenyl)-isophthalic acid diamide is 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, and even more preferably 1.2 parts by mass or more, and particularly preferably 1.5 parts by mass or more, based on 1 part by mass of leuco dye. The content of 5-(N-3-methylphenyl-sulfonamide)-N′,N″-bis-(3-methylphenyl)-isophthalic acid diamide is preferably 10 parts by weight or less, more preferably 5 parts by weight or less, even more preferably 4 parts by weight or less, and particularly preferably 3.5 parts by weight or less, based on 1 part by weight of leuco dye. A content of 0.5 parts by weight or more can improve recording performance and also improve the alcohol resistance and plasticizer resistance of the recording section, while a content of 10 parts by weight or less can effectively reduce background fogging in high-temperature environments.

[0190] Provided that the effects of the present invention are not compromised, the thermal recording layer may contain other color developers (second color developers). Specific examples of second color developers may be those listed as specific examples of color developers in the thermal recording layer portion of A. thermal recorder (A) above.

[0191] In this invention, the second colorimetric agent is preferably a urea carbamate compound represented by formula (2), such as 4,4′-bis[(4-methyl-3-phenoxycarbonylaminophenyl)ureo]diphenyl sulfone, 4,4′-bis[(2-methyl-5-phenoxycarbonylaminophenyl)ureo]diphenyl sulfone, or 4-(2-methyl-3-phenoxycarbonylaminophenyl)ureo-4′-(4-methyl-5-phenoxycarbonylaminophenyl)ureodiphenyl sulfone, a cross-linked diphenyl sulfone compound represented by formula (3), an N,N′-diarylurene compound represented by formula (4), a compound represented by formula (5), or 4,4′-bis(3-tolylureo)diphenylmethane. This allows for the full realization of the effects of this invention.

[0192]

[0193] (where r represents an integer from 1 to 6).

[0194]

[0195] (where R) 3 C represents 1-12 Alkyl, C 7-12 Aryl alkyl, or C 6-12 Aryl group, wherein the aralkyl group and the aryl group may optionally be C 1-12 Alkyl, C 1-12 Alkoxy, C 6-12 Aryl or halogen atom substitution, multiple R 3 They can be the same or different, A 1 Represents a hydrogen atom or C 1-4 Alkyl group, multiple A groups 1 (Can be the same or different).

[0196]

[0197] (where R) 4 To R 8 Same or different, and representing hydrogen atom, halogen atom, nitro, amino, alkyl, alkoxy, aryloxy, alkyl carbonyloxy, aryl carbonyloxy, alkyl carbonylamino, aryl carbonylamino, alkyl sulfonylamino, aryl sulfonylamino, monoalkylamino, dialkylamino or arylamino).

[0198] In formula (4) of the N,N′-diarylurea compounds included as the second colorimetric agent, R 3 C1-12 The alkyl group can be straight-chain, branched, or alicyclic, preferably C10. 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 used herein include C14. 1-12 The alkyl moiety of alkoxy groups.

[0199] Arylalkyl refers to arylalkyl, C 7-12 Examples of aralkyl groups include benzyl, 1-phenylethyl, 2-phenylethyl, and 3-phenylpropyl.

[0200] An aryl group refers to a monocyclic or polycyclic aromatic hydrocarbon group formed from one or more 5- or 6-membered aromatic hydrocarbon rings. C 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.

[0201] Examples of halogen atoms include fluorine, chlorine, bromine, and iodine.

[0202] In equation (4), each R 3 The substitution positions of -SO3- can be the same or different. The substitution positions are preferably at the 3-, 4-, or 5-position, and more preferably at the 3-position. When C, represented by R2... 7-12 Arane and C 6-12 When aryl groups are substituted, there is no particular limitation on the number of substituents, for example, 1 to 4.

[0203] By A 1 C represents 1-4 Alkyl groups can be straight-chain or branched. Examples include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, and tert-butyl.

[0204] Each A 1 The substitution positions can be the same or different. The substitution positions are preferably 3-position, 4-position, or 5-position.

[0205] There are no particular limitations on the N,N'-diarylurea compounds represented by formula (4), 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-(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-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. N,N'-di-[3-(p-toluenesulfonyloxy)phenyl]urea is preferred.

[0206] By R 4 To R 8 The halogen atom represented can be a fluorine atom, a chlorine atom, or a bromine atom, with fluorine and chlorine atoms being preferred.

[0207] The alkyl group can be straight-chain, branched, or cyclic, preferably straight-chain or branched, and more preferably straight-chain alkyl. Typically, the alkyl group is C10. 1-12 Alkyl, preferably C 1-8 Alkyl, more preferably C 1-6 Alkyl, and more preferably C 1-4 alkyl.

[0208] The alkoxy group can be straight-chain, branched, or cyclic, preferably straight-chain or branched, and more preferably straight-chain alkoxy. Typically, the alkoxy group is C10-32 ... 1-12 Alkoxy, preferably C 2-8 Alkoxy, more preferably C 2-6 Alkyl group, and more preferably C 2-4 Alkyl group.

[0209] The alkyl carbonyloxy group can be straight-chain, branched, or cyclic, preferably straight-chain or branched, and more preferably straight-chain. The alkyl carbonyloxy group is also preferably C10. 1-10 Alkyl carbonyloxy group.

[0210] The alkyl carbonyl amino group can be straight-chain, branched, or cyclic, preferably straight-chain or branched, and more preferably straight-chain. The alkyl carbonyl amino group is also preferably C10. 1-10 Alkyl carbonyl amino.

[0211] Alkylsulfonamides can be linear, branched, or cyclic, preferably linear or branched, and more preferably linear. Alkylsulfonamides are also preferred. 1-10 Alkylsulfonylamino.

[0212] An aryl group is a monocyclic or polycyclic aromatic hydrocarbon group formed from one or more five- or six-membered aromatic hydrocarbon rings. Examples of aryl groups include phenyl, naphthyl, and biphenyl.

[0213] The preferred aryloxy group is C. 6-12 Aryloxy group. The aryl carbonyloxy group is preferably C. 6-12 Arylcarbonyloxy group. The arylcarbonylamino group is preferably C10. 6-12 Aryl carbonyl amino. Aryl sulfonyl amino is preferably C. 6-12 Arylsulfonamide.

[0214] The monoalkylamino group can be straight-chain, branched, or cyclic, preferably straight-chain or branched, and more preferably straight-chain. Monoalkylamino groups having 1 to 10 carbon atoms are also preferred.

[0215] Dialkylamino groups can be straight-chain, branched, or cyclic, with straight-chain or branched dialkylamino groups being preferred, and straight-chain dialkylamino groups being more preferred. Dialkylamino groups having 1 to 10 carbon atoms are also preferred.

[0216] The aryl amino group can be a monoaryl amino group or a diaryl amino group, preferably C10. 6-12 Monoarylamino.

[0217] Specific examples of compounds represented by equation (5) include those in which R 4 To R 8 It is an alkyl or hydrogen atom, preferably R. 4 To R 8 It is C 1-8 Straight-chain alkyl or hydrogen atom, more preferably R 4 To R 8 C 1-4 Straight-chain alkyl or hydrogen atom, and more preferably R 4 To R 8 Compounds that have methyl or hydrogen atoms.

[0218] Specific examples of other compounds represented by equation (5) include R. 4 R 5 R 7and R 8 It is a hydrogen atom and R 6 It can be a hydrogen atom, halogen atom, nitro group, amino group, alkyl group, alkoxy group, aryloxy group, alkyl carbonyloxy group, alkyl carbonyl amino group, aryl carbonyl amino group, alkyl sulfonyl amino group, aryl sulfonyl amino group, monoalkyl amino group, dialkyl amino group or aryl amino group (preferably hydrogen atom or alkyl group, more preferably hydrogen atom or C group). 1-8 Alkyl group, more preferably hydrogen atom or C 1-4 Compounds of alkyl groups, with particular preference for methyl groups.

[0219] In the diphenylurea structure of formula (5), the position of the substituent attached to a benzene ring relative to the amino carbonyl group on the benzene ring can be ortho, meta, or para, preferably ortho or meta, and more preferably meta.

[0220] The compound represented by formula (5) is not particularly limited, but is preferably selected from at least one of the group consisting of 3-[(phenylcarbamoyl)amino]phenyl-4-methylbenzenesulfonate, 2-[(phenylcarbamoyl)amino]phenyl-4-methylbenzenesulfonate and 4-[(phenylcarbamoyl)amino]phenyl-4-methylbenzenesulfonate. Among them, 3-[(phenylcarbamoyl)amino]phenyl-4-methylbenzenesulfonate is preferred.

[0221] There is no particular limitation on the content of the second color developer, but it is preferably 0.2 to 3 parts by mass based on 1 part by mass of leuco dye. The content of the second color developer is also preferably about 0.2 to 0.5 parts by mass based on 1 part by mass of 5-(N-3-methylphenyl-sulfonamide)-N′,N″-bis-(3-methylphenyl)-isophthalic acid diamide used as the first color developer.

[0222] Inorganic Pigment II

[0223] The thermal recording layer of the present invention comprises an inorganic pigment I 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, and most preferably 65 ml / 100 g or less. Using inorganic pigment II significantly increases alcohol resistance and plasticizer resistance. From the viewpoint of effectively reducing printing problems such as printhead residue and adhesion, the oil absorption of inorganic pigment II is preferably 30 ml / 100 g or more. The thermal recording layer of the present invention may comprise a pigment with an oil absorption greater than 130 ml / 100 g, provided that the effect of the present invention is not compromised. 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 per part by weight. 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 in JIS K 5101.

[0224] Various inorganic pigments can be used as inorganic pigment II. Specific examples include, for example, calcium carbonate such as light calcium carbonate, aluminum hydroxide, clay such as calcined kaolin and kaolin, and inorganic pigments such as 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.

[0225] 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.

[0226] 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.

[0227] In this invention, the thermal recording layer may further contain a sensitizer. This can improve recording sensitivity. The sensitizer used may be those described in the thermal recording layer section of A. thermal recorder (A) above, and the content of the sensitizer may be set as described in the thermal recording layer section of A. thermal recorder (A) above.

[0228] As other components constituting the thermal recording layer, a binder may be used. Furthermore, if necessary, additives such as crosslinking agents, waxes, metal soaps, water resistance modifiers, dispersants, coloring dyes, and fluorescent dyes may be used. The binders and crosslinking agents used may be those described in the thermal recording layer section of A. Thermal Recorder (A) above, and the content of the binders and crosslinking agents used may be set as described in the thermal recording layer section of A. Thermal Recorder (A) above.

[0229] The thermal recording layer is formed on the base layer as follows: For example, by 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, either 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; reducing the average particle size of the dispersion to less than 2 μm, then mixing the dispersion with inorganic pigment II and optionally further mixing with binders and additives to prepare a coating for the thermal recording layer; applying the coating for the thermal recording layer onto the base layer and then drying. There is no particular limitation on the coating amount of the thermal recording layer, but for the dried coating amount, approximately 1 to 12 g / m² is preferred. 2 More preferably, about 2 to 10 g / m 2 Even more preferably, it is about 2.5 to 8 g / m³. 2 And particularly preferred is about 3 to 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.

[0230] protective layer

[0231] The thermal recorder may, as needed, include a protective layer formed on the thermal recording layer. The protective layer used may be those described in the protective layer section of A. Thermal Recorder (A) above.

[0232] Other layers

[0233] In this embodiment, the thermal recorder can be further processed to give it higher functionality and enhance its added value. The other layers used may be those described in the "Other Layers" section of A. Thermal Recorder (A) above.

[0234] thermal recording device

[0235] The thermal recorder can be manufactured by forming the aforementioned layers on a support. The methods used to form the layers can be those described in the thermal recorder section of A. Thermal Recorder (A) above.

[0236] Example

[0237] The invention is described in more detail with reference to the 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).

[0238] The hollow particles used in the examples and comparative examples are as follows.

[0239] Hollow Particle A: Average particle size (D50): 5.0 μm; Maximum particle size (D100): 13.5 μm; D100 / D50 = 2.7; 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.

[0240] Hollow Particle B: Average particle size (D50): 11 μm; Maximum particle size (D100): 23 μm; D100 / D50 = 2.1; Hollowness ratio: 93%; Proportion of particles with a diameter of less than 2 μm: 0% by volume; Solid content concentration: 15.0%; Foamed type.

[0241] 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; D100 / D50 = 1.8; Hollowness ratio: 55%; Proportion of particles with a diameter of less than 2 μm: 100 vol%; Solid content: 26.5%; Non-foaming type.

[0242] 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.

[0243] The latex used in the examples and comparative examples is as follows.

[0244] Latex A: Styrene-butadiene copolymer latex (Tg: -35℃; Particle size: 300nm; Solid content concentration: 48%)

[0245] Latex B: Styrene-butadiene copolymer latex (Tg: -10℃; Particle size: 190nm; Solid content concentration: 48%)

[0246] Latex C: Styrene-butadiene copolymer latex (trade name: L-1571, manufactured by Asahi Kasei Corporation; Tg: -3℃; particle size: 190nm; solid content: 48%)

[0247] A. Thermal recording medium (A)

[0248] Example A1

[0249] (1) Preparation of coating liquid for primer layer

[0250] A coating solution for a base coat was prepared by mixing and stirring a composition comprising 100 parts hollow particles A, 38 parts calcined kaolin (trade name: Ansilex 93, manufactured by BASF; oil absorption: 105 ml / 100 g), 79.2 parts latex A, 32 parts 25% aqueous solution of oxidized starch, 1.1 parts carboxymethyl cellulose (trade name: Cellogen AG gum, manufactured by DKS Co., Ltd.) and 100 parts water.

[0251] (2) Preparation of leuco dye dispersion (liquid A1)

[0252] 40 parts of 3-di(n-butyl)amino-6-methyl-7-aniline fluorane, 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 0.5 μm to obtain a leuco dye dispersion (liquid A1).

[0253] (3-1) Preparation of colorimetric reagent dispersion (liquid B1-1)

[0254] 40 parts of 4-hydroxy-4'-isopropoxydiphenyl sulfone, 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 colorimetric reagent dispersion (liquid B1-1).

[0255] (4-1) Preparation of preservation improver dispersion (liquid C1-1)

[0256] 40 parts of 5-(N-3-methylphenyl-sulfonamide)-N',N”-bis-(3-methylphenyl)-isophthalic acid diamide, 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 preservation improver dispersion (liquid C1-1).

[0257] (5) Preparation of sensitizer dispersion (liquid D1)

[0258] 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 D1).

[0259] (6) Preparation of coating solution for thermal recording layer

[0260] A coating solution for thermal recording layers was prepared by mixing and stirring a composition comprising 31.8 parts liquid A1, 63.6 parts liquid B1-1, 15.9 parts liquid C1-1, 22.7 parts liquid D1, 46.7 parts of 15% fully saponified polyvinyl alcohol (trade name: PVA110; degree of saponification: 99 mol%; average degree of polymerization: 1000; manufactured by Kuraray Co., Ltd.) aqueous solution, 20.8 parts latex C, 18 parts aluminum hydroxide (trade name: KH-101, manufactured by KCCorporation), 5 parts adipic acid dihydrazide (manufactured by Otsuka Chemical Co., Ltd.), and 200 parts water.

[0261] (7) Preparation of coating liquid for protective layer

[0262] A coating liquid for a protective layer was prepared by mixing and stirring a composition comprising 308 parts of an aqueous solution of 12% diacetone-modified polyvinyl alcohol (trade name: DF-10, manufactured by Japan Vam&Poval Co., Ltd.), 60 parts of kaolin (trade name: Hydragloss 90, manufactured by KaMin LLC), 5.6 parts of zinc stearate (trade name: Hidorin Z-8, manufactured by Chukyo Yushi Co., Ltd.; solid content concentration: 36%) and 150 parts of water.

[0263] (8) Preparation of thermal recording devices

[0264] The base coating liquid, the thermal recording layer coating liquid, and the protective layer coating liquid were applied at a dry weight of 4.5 g / m². 2 4.0g / 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.

[0265] Example A2

[0266] Except that the amount of liquid C1-1 was changed from 15.9 parts to 6.8 parts in the preparation of the coating liquid for the thermal recording layer in Example A1, the thermal recorder was obtained in the same manner as in Example A1.

[0267] Example A3

[0268] Except that in the preparation of the coating liquid for the thermal recording layer in Example A1, the amount of liquid B1-1 was changed from 63.6 parts to 39.8 parts, and the amount of liquid C1-1 was changed from 15.9 parts to 39.8 parts, the thermal recorder was obtained in the same manner as in Example A1.

[0269] Example A4

[0270] Except that in the preparation of the coating liquid for the thermal recording layer in Example A1, the amount of liquid B1-1 was changed from 63.6 parts to 31.8 parts, and the amount of liquid C1-1 was changed from 15.9 parts to 47.7 parts, the thermal recorder was obtained in the same manner as in Example A1.

[0271] Example A5

[0272] Except that in the preparation of the coating liquid for the thermal recording layer in Example A1, the amount of liquid B1-1 was changed from 63.6 parts to 15.9 parts, and the amount of liquid C1-1 was changed from 15.9 parts to 63.6 parts, the thermal recorder was obtained in the same manner as in Example A1.

[0273] Example A6

[0274] (3-2) Preparation of colorimetric reagent dispersion (liquid B1-2)

[0275] 40 parts of 2,4'-dihydroxydiphenyl sulfone (trade name: 2,4'-BPS, manufactured by Nicca Chemical 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 colorimetric reagent dispersion (liquid B1-2).

[0276] Except that in the preparation of the coating solution for the thermal recording layer in Example A1, the color developer dispersion was replaced by liquid B1-2 instead of liquid B1-1, the thermal recorder was obtained in the same manner as in Example A1.

[0277] Example A7

[0278] (3-3) Preparation of colorimetric reagent dispersion (liquid B1-3)

[0279] 40 parts of 4,4'-dihydroxydiphenyl sulfone (trade name: 4,4'-BPS, manufactured by Nicca Chemical 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 colorimetric reagent dispersion (liquid B1-3).

[0280] Except that in the preparation of the coating liquid for the thermal recording layer in Example A1, the color developer dispersion was replaced by liquid B1-3 instead of liquid B1-1, the thermal recorder was obtained in the same manner as in Example A1.

[0281] Example A8

[0282] (3-4) Preparation of colorimetric reagent dispersion (liquid B1-4)

[0283] 40 parts of bis(3-allyl-4-hydroxyphenyl) sulfone (trade name: TG-SH, manufactured by Nippon Kayaku 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 colorimetric reagent dispersion (liquid B1-4).

[0284] Except that in the preparation of the coating solution for the thermal recording layer in Example A1, the color developer dispersion was replaced by liquid B1-4 instead of liquid B1-1, the thermal recorder was obtained in the same manner as in Example A1.

[0285] Example A9

[0286] (3-5) Preparation of colorimetric reagent dispersion (liquid B1-5)

[0287] 40 parts of 4-hydroxyphenyl (4'-n-propoxyphenyl) sulfone (trade name: Tomirac KN, manufactured by Mitsubishi Chemical Corporation), 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 colorimetric reagent dispersion (liquid B1-5).

[0288] Except that in the preparation of the coating solution for the thermal recording layer in Example A1, the color developer dispersion was replaced by liquid B1-5 instead of liquid B1-1, the thermal recorder was obtained in the same manner as in Example A1.

[0289] Example A10

[0290] (3-6) Preparation of colorimetric reagent dispersion (liquid B1-6)

[0291] 40 parts of 4-hydroxy-4'-benzyloxydiphenyl sulfone (trade name: BPS-MBE, manufactured by Nicca Chemical 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 colorimetric reagent dispersion (liquid B1-6).

[0292] Except that in the preparation of the coating solution for the thermal recording layer in Example A1, the color developer dispersion was replaced by liquid B1-6 instead of liquid B1-1, the thermal recorder was obtained in the same manner as in Example A1.

[0293] Example A11

[0294] (3-7) Preparation of colorimetric reagent dispersion (liquid B1-7)

[0295] 40 parts of 4-allyloxy-4'-hydroxydiphenyl sulfone (trade name: BPS-MAE, manufactured by Nicca Chemical 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 colorimetric reagent dispersion (liquid B1-7).

[0296] Except that in the preparation of the coating solution for the thermal recording layer in Example A1, the color developer dispersion was replaced by liquid B1-7 instead of liquid B1-1, the thermal recorder was obtained in the same manner as in Example A1.

[0297] Example A12

[0298] (3-8) Preparation of colorimetric reagent dispersion (liquid B1-8)

[0299] 40 parts of N-p-toluenesulfonyl-N'-3-(p-toluenesulfonyloxy)phenylurea (trade name: PF-201, manufactured by Solenis), 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 colorimetric reagent dispersion (liquid B1-8).

[0300] Except that in the preparation of the coating liquid for the thermal recording layer in Example A1, the color developer dispersion was replaced by liquid B1-8 instead of liquid B1-1, the thermal recorder was obtained in the same manner as in Example A1.

[0301] Example A13

[0302] (3-9) Preparation of colorimetric reagent dispersion (liquid B1-9)

[0303] 40 parts of N-[2-(3-phenylureo)phenyl]benzenesulfonamide (trade name: NKK-1304, manufactured by Nippon Soda 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 colorimetric reagent dispersion (liquid B1-9).

[0304] Except that in the preparation of the coating solution for the thermal recording layer in Example A1, the color developer dispersion was replaced by liquid B1-9 instead of liquid B1-1, the thermal recorder was obtained in the same manner as in Example A1.

[0305] Example A14

[0306] Except that in the preparation of the coating liquid for the base coating in Example A13, the amount of hollow particles A was changed from 100 parts to 46.7 parts, the amount of calcined kaolin was changed from 38 parts to 46 parts, and the amount of water was changed from 100 parts to 145 parts, the thermal recorder was obtained in the same manner as in Example A13.

[0307] Example A15

[0308] Except that latex B was used instead of latex A in the preparation of the base coating liquid in Example A13, the thermal recorder was obtained in the same manner as in Example A13.

[0309] Example A16

[0310] Except that latex C was used instead of latex A in the preparation of the base coating liquid in Example A13, the thermal recorder was obtained in the same manner as in Example A13.

[0311] Example A17

[0312] Except that hollow particles B were used instead of hollow particles A in the preparation of the coating liquid for the base layer in Example A13, the thermal recorder was obtained in the same manner as in Example A13.

[0313] Example A18

[0314] Except that in the preparation of the coating liquid for the base layer in Example A13, 56.6 parts of hollow particles C were used instead of 100 parts of hollow particles A, and the amount of water was changed from 100 parts to 175 parts, the thermal recorder was obtained in the same manner as in Example A13.

[0315] Comparative Example A1

[0316] Except that in the preparation of the coating liquid for the thermal recording layer in Example A1, the amount of liquid B1-1 was changed from 63.6 parts to 79.5 parts, and the amount of liquid C1-1 was changed from 15.9 parts to 0 parts, the thermal recorder was obtained in the same manner as in Example A1.

[0317] Comparative Example A2

[0318] (4-2) Preparation of preservation improver dispersion (liquid C1-2)

[0319] 40 parts of a cross-linked diphenyl sulfone compound represented by formula (3) (trade name: D-90, manufactured by Nippon Soda 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 preservation improver dispersion (liquid C1-2).

[0320] Except that in the preparation of the coating liquid for the thermal recording layer in Example A1, the preservation improver dispersion was replaced by liquid C1-2 instead of liquid C1-1, the thermal recorder was obtained in the same manner as in Example A1.

[0321] Comparative Example A3

[0322] (4-3) Preparation of preservation improver dispersion (liquid C1-3)

[0323] 40 parts of 4,4'-bis[(4-methyl-3-phenoxycarbonylaminophenyl)ureo]diphenyl sulfone (trade name: UU, manufactured by Chemipro Kasei Kaisha, 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 preservation improver dispersion (liquid C1-3).

[0324] Except that in the preparation of the coating liquid for the thermal recording layer in Example A1, the preservation improver dispersion was replaced by liquid C1-3 instead of liquid C1-1, the thermal recorder was obtained in the same manner as in Example A1.

[0325] Comparative Example A4

[0326] Except that in the preparation of the coating liquid for the thermal recording layer in Example A11, the preservation improver dispersion is replaced by liquid C1-2 instead of liquid C1-1, the thermal recorder is obtained in the same manner as in Example A11.

[0327] Comparative Example A5

[0328] Except that in the preparation of the coating liquid for the thermal recording layer in Example A11, the preservation improver dispersion is replaced by liquid C1-3 instead of liquid C1-1, the thermal recorder is obtained in the same manner as in Example A11.

[0329] Comparative Example A6

[0330] Except that in the preparation of the coating liquid for the thermal recording layer in Example A12, the amount of liquid B1-8 was changed from 63.6 parts to 79.5 parts, and the amount of liquid C1-1 was changed from 15.9 parts to 0 parts, the thermal recorder was obtained in the same manner as in Example A12.

[0331] Comparative Example A7

[0332] Except that in the preparation of the coating liquid for the thermal recording layer in Example A12, the preservation improver dispersion is replaced by liquid C1-2 instead of liquid C1-1, the thermal recorder is obtained in the same manner as in Example A12.

[0333] Comparative Example A8

[0334] Except that in the preparation of the coating liquid for the thermal recording layer in Example A12, the preservation improver dispersion was replaced by liquid C1-3 instead of liquid C1-1, the thermal recorder was obtained in the same manner as in Example A12.

[0335] Comparative Example A9

[0336] Except that in the preparation of the coating liquid for the thermal recording layer in Example A13, the amount of liquid B1-9 was changed from 63.6 parts to 79.5 parts, and the amount of liquid C1-1 was changed from 15.9 parts to 0 parts, the thermal recorder was obtained in the same manner as in Example A13.

[0337] Comparative Example A10

[0338] Except that in the preparation of the coating liquid for the thermal recording layer in Example A13, the preservation improver dispersion was replaced by liquid C1-2 instead of liquid C1-1, the thermal recorder was obtained in the same manner as in Example A13.

[0339] Comparative Example A11

[0340] Except that in the preparation of the coating liquid for the thermal recording layer in Example A13, the preservation improver dispersion was replaced by liquid C1-3 instead of liquid C1-1, the thermal recorder was obtained in the same manner as in Example A13.

[0341] The embodiments and comparative examples were evaluated according to the following methods. Table 1 shows the results.

[0342] Record concentration

[0343] Images were recorded on each thermal recorder using a thermal recording tester (trade name: TH-PMD, manufactured by Ohkura Electric Co., Ltd.) at applied energies of 0.17 mJ / point (medium-energy color concentration) and 0.25 mJ / point (high-energy color concentration). The reflectance concentration of the recorded portion was measured using a spectrophotometer (X-Rite 504, manufactured by X-Rite). Higher concentrations are preferred if preservation is comparable; the following criteria are used as guidelines for evaluation.

[0344] Medium energy color concentration

[0345] Version 1.00 and above: Excellent compatibility with high-speed printing.

[0346] Values ​​above 0.80 and below 1.00: No actual issues.

[0347] Less than 0.80: Low sensitivity with many defects such as white spots, which causes problems in practical use.

[0348] High energy color density

[0349] 1.40 and above: Excellent

[0350] Values ​​above 1.20 and below 1.40: No real issues.

[0351] Less than 1.20: Low print density, undesirable in practical use. Water resistance

[0352] 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 water at 20°C for 24 hours. Before and after this immersion treatment, the reflectance concentration of the recording section was measured using a spectrophotometer (X-Rite 504, manufactured by X-Rite). Furthermore, the residual percentage of the recording section was obtained according to the following equation. The residual percentage was evaluated according to the following criteria.

[0353] Residual percentage (%) = (Record concentration after treatment / Record concentration before treatment) × 100

[0354] Residual percentage above 80%: Excellent

[0355] Residual percentage above 60% but less than 80%: No practical problems.

[0356] A residual percentage of less than 60% indicates a significant reduction in the concentration of the processed recordings, which presents problems in practical use.

[0357] Water-resistant plasticizer properties

[0358] 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 prepared 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 by placing it at 40°C for 24 hours. Before and after this treatment, the reflectance concentration of the recording section was measured using a spectrophotometer (X-Rite504, manufactured by X-Rite). Furthermore, the residual percentage of the recording section was obtained according to the following equation. The residual percentage was evaluated according to the following criteria.

[0359] Residual percentage (%) = (Record concentration after treatment / Record concentration before treatment) × 100

[0360] Residual percentage above 80%: Excellent

[0361] Residual percentage above 60% but less than 80%: No practical problems.

[0362] A residual percentage of less than 60% indicates a significant reduction in the concentration of the processed recordings, which presents problems in practical use.

[0363] alcohol resistance

[0364] 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. Before and after this treatment, the reflectance concentrations of the background and recording regions were measured using a spectrophotometer (X-Rite 504, manufactured by X-Rite). Furthermore, the residual percentage of the recording region was calculated according to the following equation. The background concentration and residual percentage after treatment were evaluated according to the following criteria.

[0365] Residual percentage (%) = (Record concentration after treatment / Record concentration before treatment) × 100

[0366] Background concentration below 0.10: Excellent

[0367] Background concentration greater than 0.10 and less than 0.20: Fogging is sometimes observed, but there is no actual problem.

[0368] Background concentration greater than 0.20: Significant fogging occurs, causing problems in actual use.

[0369] Residual percentage above 80%: Excellent

[0370] Residual percentage above 60% but less than 80%: No practical problems.

[0371] A residual percentage of less than 60% indicates a significant reduction in the concentration of the processed recordings, which presents problems in practical use.

[0372] Table 1

[0373]

[0374] B. Thermal recording medium (B)

[0375] Example B1

[0376] (1) Preparation of coating liquid for primer layer

[0377] 100 parts of hollow granules A, 38 parts of calcined kaolin (trade name: Ansilex 93, produced by BASF AG; oil absorption: 105ml / 100g), 79.2 parts of latex A, 32 parts of 25% oxidized starch solution, 1.1 parts of carboxymethyl cellulose (trade name: Cellogen AG gum, produced by DKS Co., Ltd.) and 100 parts of water were mixed and stirred to obtain a coating liquid for the base layer.

[0378] (2) Preparation of leuco dye dispersion (liquid A2)

[0379] 40 parts of 3-di(n-butyl)amino-6-methyl-7-aniline fluorane, 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 0.5 μm to obtain a leuco dye dispersion (liquid A2).

[0380] (3) Preparation of colorimetric reagent dispersion (liquid B2)

[0381] 40 parts of 5-(N-3-methylphenyl-sulfonamide)-N',N”-bis-(3-methylphenyl)-isophthalic acid diamide, 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 B2).

[0382] (4) Preparation of sensitizer dispersion (liquid C2)

[0383] 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 C2).

[0384] (5) Preparation of coating solution for thermal recording layer

[0385] A coating solution for thermal recording layers was prepared by mixing and stirring 29.5 parts of liquid A2, 63.6 parts of liquid B2, 45.5 parts of liquid C2, 70 parts of 10% fully saponified polyvinyl alcohol (trade name: PVA117; degree of saponification: 99 mol%; average degree of polymerization: 1700; manufactured by Kuraray Co., Ltd.), 20.8 parts of styrene-butadiene copolymer latex (trade name: L-1571; manufactured by Asahi Kasei Corporation; solid content concentration: 48%), 20 parts of calcium carbonate (trade name: Brilliant-15; manufactured by Shiraishi Kogyo Kaisha, Ltd.; oil absorption: 56 ml / 100 g), 2 parts of adipic acid dihydrazide (manufactured by Otsuka Chemical Co., Ltd.), and 150 parts of water.

[0386] (6) Preparation of coating liquid for protective layer

[0387] A composition comprising 317 parts of an aqueous solution of 12% diacetone-modified polyvinyl alcohol (trade name: DF-10, manufactured by Japan Vam & Poval Co., Ltd.), 60 parts of kaolin (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 300 parts of water was mixed and stirred to obtain a coating liquid for a protective layer.

[0388] (7) Production of thermal recording devices

[0389] The base coating liquid, the thermal recording layer coating liquid, and the protective layer coating liquid were applied at a dry weight of 4.5 g / m². 2 3.8g / m 2 and 2.3g / 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.

[0390] Example B2

[0391] Except that aluminum hydroxide (trade name: Higilite H-42, manufactured by Showa Keikinzoku, oil absorption: 43 ml / 100 g) was used instead of calcium carbonate in the preparation of the coating liquid for the thermal recording layer in Example B1, the thermal recorder was obtained in the same manner as in Example B1.

[0392] Example B3

[0393] Except that in the preparation of the coating liquid for the thermal recording layer in Example B1, clay (trade name: HG90, manufactured by KaMin LLC, oil absorption: 46 ml / 100 g) was used instead of calcium carbonate, the thermal recorder was obtained in the same manner as in Example B1.

[0394] Example B4

[0395] Except that in the preparation of the coating solution for the thermal recording layer in Example B1, the calcium carbonate (trade name: Brilliant-15, manufactured by Shiraishi Kogyo Kaisha, Ltd., oil absorption: 56 ml / 100 g) was replaced with another calcium carbonate (trade name: Cal-Light-KT, manufactured by Shiraishi Kogyo Kaisha, Ltd., oil absorption: 120 ml / 100 g), the thermal recorder was obtained in the same manner as in Example B1.

[0396] Example B5

[0397] Except for changing 79.2 parts of latex A to 79.2 parts of latex B in the preparation of the base coating liquid in Example B1, the thermal recorder was obtained in the same manner as in Example B1.

[0398] Example B6

[0399] Except for changing 79.2 parts of latex A to 79.2 parts of latex C in the preparation of the base coating liquid in Example B1, the thermal recorder was obtained in the same manner as in Example B1.

[0400] Example B7

[0401] Except that in the preparation of the base coating liquid in Example B1, 100 parts of hollow particles A were replaced with 100 parts of hollow particles B, the thermal recorder was obtained in the same manner as in Example B1.

[0402] Example B8

[0403] Except that in the preparation of the coating liquid for the base layer in Example B1, the amount of calcined kaolin was changed from 38 parts to 66 parts, the amount of latex A was changed from 79.2 parts to 20.8 parts, and the amount of water was changed from 100 parts to 130 parts, the thermal recorder was obtained in the same manner as in Example B1.

[0404] Example B9

[0405] Except that in the preparation of the coating liquid for the base coating in Example B1, the amount of calcined kaolin was changed from 38 parts to 66 parts, the amount of latex A was changed from 79.2 parts to 20.8 parts to latex C, the amount of hollow particles A was changed from 100 parts to 56.6 parts to hollow particles C, and the amount of water was changed from 100 parts to 180 parts, the thermal recorder was obtained in the same manner as in Example B1.

[0406] Comparative Example B1

[0407] Except that in the preparation of the coating liquid for the thermal recording layer in Example B1, amorphous silica (trade name: Nipsil E-743, manufactured by Tosoh Silica Corporation, oil absorption: 150-170 ml / 100 g) was used instead of calcium carbonate, the thermal recorder was obtained in the same manner as in Example B1.

[0408] Comparative Example B2

[0409] (8) Preparation of colorimetric reagent dispersion (liquid D2)

[0410] 40 parts of 4-hydroxy-4'-isopropoxydiphenyl sulfone (trade name: D-8, manufactured by Nippon Soda 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 colorimetric reagent dispersion (liquid D2).

[0411] Except that in the preparation of the coating solution for the thermal recording layer in Comparative Example B1, chromogenic dispersion liquid D2 was used instead of chromogenic dispersion liquid B2, the thermal recorder was obtained in the same manner as in Example B1.

[0412] The embodiments and comparative examples were evaluated according to the following methods. Table 2 shows the results.

[0413] Record concentration

[0414] Images were recorded on each thermal recorder using a thermal recording tester (trade name: TH-PMD, manufactured by Ohkura Electric Co., Ltd.) with an applied energy of 0.16 mJ / point (medium energy color density). The print density was measured using a spectrophotometer (X-Rite504, manufactured by X-Rite). A higher value indicates a denser print.

[0415] The evaluation criteria for medium-energy color concentration are as follows.

[0416] Color density of 0.90 or higher: Excellent compatibility with high-speed printing.

[0417] Color density of 0.80 or higher and less than 0.90: necessary for practical use.

[0418] Color concentration less than 0.80: Low sensitivity with many defects such as white spots, causing problems in practical use.

[0419] Alcohol resistance

[0420] The 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) ethanol solution for 30 minutes. After this treatment, the optical density of the printed section was measured using a spectrophotometer (X-Rite 504, manufactured by X-Rite).

[0421] The evaluation criteria are as follows.

[0422] The density of the printed section after processing is above 1.00: Excellent.

[0423] The density of the printed part after processing is above 0.80 and below 1.00: No problems in actual use.

[0424] After processing, the print density is less than 0.80: the print disappears, causing problems in actual use.

[0425] Plasticizer resistance

[0426] 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 each thermal recorder, developed using a label printer (trade name: L-2000, manufactured by Ishida Co., Ltd.), was placed on the film. The wrapping film was then wrapped three more times around the thermal recorder, and the wrapped thermal recorder was placed at 40°C for 24 hours. After this treatment, the optical density of the recording section was measured using a spectrophotometer (X-Rite 504, manufactured by X-Rite).

[0427] The evaluation criteria are as follows.

[0428] The concentration in the recording section after processing is above 1.00: Excellent.

[0429] The concentration in the recording section after processing is above 0.80 and below 1.00: No problems were found in actual use.

[0430] After processing, the concentration in the recording section is less than 0.80: the printout disappears, causing problems in actual use.

[0431] 100℃ heat resistance

[0432] Samples of each thermal recorder that had been developed using a label printer (trade name: L-2000, manufactured by Ishida Co., Ltd.) were placed in a 100°C room for 1 hour. After this treatment, the optical density of the blank paper portion was measured using a spectrophotometer (X-Rite504, manufactured by X-Rite).

[0433] The evaluation criteria are as follows.

[0434] The concentration of the blank paper after treatment is below 0.10: Excellent.

[0435] The concentration of the blank paper after treatment is greater than 0.10 and less than 0.20: No problems in actual use.

[0436] If the density of the blank paper portion after processing is greater than 0.20, the background fogging is too severe, causing problems in actual use.

[0437] Table 2

[0438]

[0439] As shown in Table 2, the thermal recorders of Examples B1 to B9 exhibit excellent alcohol resistance, plasticizer resistance, and heat background fogging resistance. In contrast, Comparative Example B1 shows poor alcohol resistance and significantly poor plasticizer resistance. Due to the change in the developer, Comparative Example B2 exhibits significantly poor alcohol resistance, but its plasticizer resistance is slightly better than Comparative Example B1, making it unsuitable for practical use. Furthermore, the concentration of the blank paper portion shows significantly poor heat resistance at 100°C.

Claims

1. A thermal recording medium, comprising at least 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 contains a leuco dye and a color developer. in (A) The thermal recording layer comprises 5-(N-3-methylphenyl-sulfonamide)-N′,N′′-bis-(3-methylphenyl)-isophthalic acid diamide as a preservation improver and N-[2-(3-phenylureo)phenyl]benzenesulfonamide as a colorimetric agent. The hollow particles have an average particle size (D50) of 4.0~15μm, and The volume percentage of hollow particles with a diameter of less than 2.0 μm is less than 1%; or (B) The thermal recording layer contains 5-(N-3-methylphenyl-sulfonamide)-N′,N′′-bis-(3-methylphenyl)-isophthalic acid diamide as a color developer, and contains an inorganic pigment II with an oil absorption of less than 100 mL / 100 g.

2. The thermal recorder according to claim 1, wherein (A) the thermal recording layer comprises 5-(N-3-methylphenyl-sulfonamide)-N′,N′′-bis-(3-methylphenyl)-isophthalic acid diamide as a preservation improver and N-[2-(3-phenylureo)phenyl]benzenesulfonamide as a colorimetric agent. The hollow particles have an average particle size (D50) of 4.0~15μm, and The volume percentage of hollow particles with a diameter of less than 2.0 μm is less than 1%.

3. The thermal recorder according to claim 1, wherein the thermal recording layer (B) comprises 5-(N-3-methylphenyl-sulfonamide)-N′,N′′-bis-(3-methylphenyl)-isophthalic acid diamide as a color developer and an inorganic pigment II having an oil absorption of less than 100 ml / 100 g.

4. The thermal recorder according to claim 3, comprising at least one inorganic pigment II selected from the group consisting of calcium carbonate, aluminum hydroxide and clay.

5. The thermal recorder according to claim 3, comprising an inorganic pigment I with an oil absorption of 130 mL / 100 g or less.

6. The thermal recorder according to claim 3, comprising at least one inorganic pigment selected from the group consisting of calcium carbonate, aluminum hydroxide and clay.

7. The thermal recorder of claim 3, wherein the thermal recording layer comprises at least one selected from the group consisting of: Urea carbamate compounds represented by the following formula (2): ， Crosslinked diphenyl sulfone compounds represented by the following formula (3): ， Where r represents an integer from 1 to 6, N,N′-diarylurea compounds represented by the following formula (4): ， Where R 3 C represents 1-12 Alkyl, C 7-12 Aryl or C 6-12 Aryl group, wherein the aralkyl group and the aryl group may optionally be C 1-12 Alkyl, C 1-12 Alkoxy, C 6-12 Aryl or halogen atom substitution, multiple R 3 They can be the same or different, A 1 Represents a hydrogen atom or C 1-4 Alkyl group, multiple A groups 1 They can be the same or different. Compounds represented by the following formula (5): ， Where R 4 To R 8 The same or different and representing hydrogen atom, halogen atom, nitro, amino, alkyl, alkoxy, aryloxy, alkylcarbonyloxy, arylcarbonyloxy, alkylcarbonylamino, arylcarbonylamino, alkylsulfonylamino, arylsulfonylamino, monoalkylamino, dialkylamino, or arylamino, and 4,4′-Bis(3-Tolylureo)diphenylmethane.

8. The thermal recorder according to any one of claims 1 to 7, in The hollow particles have a maximum particle size (D100) of 10~30μm and an average particle size (D50) of 4.0~15μm. The ratio of the maximum particle size (D100) to the average particle size (D50), D100 / D50, is 1.8 to 3.0, and The volume percentage of particles with a diameter of less than 2.0 μm is less than 1%.

9. The thermal recorder according to any one of claims 1 to 7, wherein the hollow particle has a hollowness of 80 to 98%.

10. The thermal recorder according to any one of claims 1 to 7, wherein the binder in the undercoat comprises a binder resin having a glass transition temperature of -10°C or less.

11. The thermal recorder according to any one of claims 1 to 7, further comprising an adhesive layer on at least one surface of the support.

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