JPH0513073B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an image recording material in which thermal transfer is performed by heating the recording material in response to an applied signal by means such as a thermal head, laser, flash light, or direct application of an electric signal. [Prior Art] Many thermal recording methods have been proposed since ancient times that utilize changes in the physical properties and chemical reactivity of materials in response to the application of thermal energy.
Among them, dye coloring reactions between colorless dyes such as crystal violet lactone, fluoran series, and spiropyran series, and phenolic compounds such as bisphenol A, and other organic acids and inorganic acids, and organic acid metal salts,
A thermosensitive color recording method that utilizes thermal reactions with organic reducing agents such as phenols, metal sulfides, organic chelating agents, and organic sulfur compounds, and changes in thermophysical properties such as heat melting and heat sublimation properties are used to create inks and 2. Description of the Related Art In recent years, thermal transfer recording methods in which coloring materials are transferred to a recording medium such as paper have been actively researched and efforts have been made to improve them. In particular, the latter thermal transfer recording method has the ability to record on plain paper, the light resistance and stability of recorded images, and
Since it has advantages such as good storage stability, simple recording mechanism, and high reliability, it is used in printers, facsimile machines, copying machines, etc. However, in the case of the method of thermally sublimating the dye, it has the advantage of being able to reproduce continuous gradation of density, but on the other hand, it has poor recording sensitivity, storage stability of the recording medium, fixing stability of the recorded image, and light fastness. etc. There is a problem. In addition, in the case of a method of thermally melting the ink and transferring and recording the ink corresponding to the applied signal onto paper etc., the above problem is reduced, but usually a crystalline wax with a low melting point is used as a binder for the heat-sensitive ink layer. Therefore, there are problems such as a decrease in resolution and weak strength of transferred and fixed images due to thermal diffusion in the recording medium. Further, crystalline waxes have the disadvantage that it is difficult to obtain clear images due to light scattering of the crystalline phase. In other words, in order to obtain clear color images, especially pictorial full-color reproduction images, by overlapping recording of ink materials several times, magenta, yellow, and cyan ink materials are usually used. secondary color and even 3
The next color is obtained. For example, when a secondary color is obtained by superimposing two types of ink materials, the color difference between the actually obtained secondary color and the intended secondary color is determined by the transparency of the ink materials. When overlapping recording is performed, at least if the transparency of the ink material overlaid on the upper layer, or more precisely, the transparency of the ink material binding layer, is good, the reflected light from the overlapping ink layers will be reflected from the pigment itself. Due to the characteristics, the secondary color reflected light becomes closer to that of the reflected light, and the color reproducibility becomes better accordingly. Conventionally, examples of using resin as a binding component of a heat-sensitive ink layer include JP-A-54-87234 and JP-A-56-
No. 98269, etc. are known, but all of these are aimed at improving the fixation and durability of prints for thermal ink materials that use the wax as a binder, and they are used as a binder for the purpose of color reproduction. There is no technical disclosure focusing on the transparency of ingredients. [Problems to be Solved by the Invention] Therefore, an object of the present invention is to provide a thermal transfer recording material that enables clear color reproduction. Another object of the present invention is to provide a heat-sensitive transfer recording material with good resolution. Still another object of the present invention is to provide a thermal transfer recording material with good recording sensitivity, transfer and fixing properties. [Means and effects for solving the problem] As a result of intensive studies, the present inventors have changed the binder of the thermal ink material from a conventional one mainly composed of crystalline waxes to a substantially amorphous polyester. The present invention was completed based on the discovery that the object of the present invention can be achieved by changing the mold release material to one containing a release material as the main component. That is, the present invention provides a recording material in which a heat-melting thermal ink material layer is provided on a support, in which the thermal ink material has a glass transition temperature of 40°C or higher, a number average molecular weight of 10,000 or lower, and a clear The main components are a transparent polyester resin that does not show a melting point, a coloring agent, and a mold release substance, and the weight ratio of the polyester resin and the mold release substance is 70:30 to 99:1.
This is a heat-sensitive recording material characterized by the following. The polyester resin used as a binder resin in the ink material of the present invention (hereinafter referred to as the polyester resin of the present invention) is an amorphous polyester resin that has been conventionally used as a base material for thermal transfer materials. It is different from crystalline polyester resins such as polyethylene terephthalate. The polyester resin of the present invention is a transparent polyester resin that has a glass transition temperature of 40° C. or higher, a number average molecular weight of 10,000 or lower, and does not exhibit a clear melting point above the glass transition temperature. Waxes conventionally used as binding materials for thermal ink materials include paraffin wax, carnauba wax, montan wax, beeswax, wood wax, candelilla wax, low molecular weight polyethylene, α-olefin oligomer, and these. If necessary, mineral oil such as spindle oil, vegetable oil such as linseed oil and tung oil, plasticizers such as dioctyl phthalate and dibutyl phthalate, and higher grades such as oleic acid and stearic acid are added. A thermal transfer recording material was produced by mixing and dispersing fatty acids, their metal salts, amides, and other derivatives together with dyes and pigments, and coating the mixture on a thin layer of plastic film or capacitor paper. Waxes, which are conventional binding materials, have a relatively clear melting point in the temperature range of about 50℃ to about 150℃ because they are crystalline, and when heated above the melting point, they rapidly change from a solid phase to a liquid phase. change into phases. And at a temperature about 30℃ higher than the melting point, about 10 ^-2 to about
It becomes a low viscosity liquid of 10 poise. On the other hand, in the case of an amorphous polyester such as the polyester resin of the present invention, there is essentially no melting point, and the solid phase gradually changes from the liquid phase to the glass transition temperature (Tg). , does not show a clear melting point above the glass transition temperature. The viscosity change during this period basically follows the WLF equation or the Andrade equation, and from Tg
It typically maintains a viscosity of 10 ³ to 10 ⁵ poise even at temperatures 50°C higher. In the case of thermal transfer recording, the transfer and fixing sensitivity is basically controlled by the melt viscosity and melt viscoelasticity of the binding material, so using an amorphous polymer as a binding material for thermal ink is This is obviously disadvantageous in terms of sensitivity. However, we found that using a transparent polyester without a well-defined melting point with a specific molecular weight and Tg as a binding material significantly improves image quality and image stability without sacrificing sensitivity. I found out what I can do. The heat-sensitive recording material of the present invention will be explained in detail below. The heat-sensitive recording material of the present invention has a polystyrene-equivalent number average molecular weight of about 10,000 or less as measured by gel permeation chromatography (GPC) method.
The polyester resin of the present invention has a glass transition temperature (Tg) measured by differential scanning calorimetry (DSC) of about 40°C or more, more preferably a number average molecular weight of about 5000 or less, and a Tg in the range of about 50°C to 80°C. is used as the main component of the binding material. is used as a binding material. If Tg is less than 50℃, especially less than 40℃,
Blocking of thermal ink materials is likely to occur,
Lack of stability during storage and use. Also, Tg is 80
If the temperature exceeds .degree. C., the thermal stability is good, but the sensitivity decreases, making it impractical and cannot be used for anything other than special purposes. It has been experimentally confirmed that even if Tg is within the above range, sensitivity decreases when the molecular weight of the amorphous polyester is high. This is presumed to be due to the cohesive force between molecules based on the entanglement of molecular chains, etc.
Good transfer and fixing properties were obtained when the number average molecular weight was about 10,000 or less, particularly 5,000 or less. The setting of the weight average molecular weight may vary depending on the use of the thermal transfer recording material. When you want to obtain a binary transfer image like with conventional wax-based inks, the weight average molecular weight is approximately 4.
It is desirable to make the softening properties of the polyester resin of the present invention more sensitive by setting the molecular weight distribution to 10,000 or less, more preferably about 10,000 or less, and narrowing the molecular weight distribution. On the other hand, it is possible to obtain density gradation and multilevel transfer images,
In addition, if it is desired to use the polyester resin repeatedly many times, it is desirable to melt-transfer the polyester resin of the present invention, which exhibits gradual softening characteristics, depending on the applied energy. It may be set to about 40,000 or more, and of course, even in this case, a good binary transfer image can be obtained. Furthermore, the shape of the molecular weight distribution does not necessarily have to be a shape having a single molecular weight peak, but may be a shape having a plurality of molecular weight peaks, or a crosslinked or branched polymer component may be used in combination. Examples of the polyester resin of the present invention include saturated dibasic acids such as phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, hexahydrophthalic anhydride, malonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, and maleic anhydride. acid, fumaric acid,
Unsaturated dibasic acids such as itaconic acid and tetrahydrophthalic anhydride, or dimer acids obtained by dimerizing linoleic acid, and ethylene glycol,
1,2-propylene glycol, 1,6-hexanediol, the following formula An amorphous polyester resin obtained by polycondensation with diols such as the bisphenol compound represented by the formula and its propylene oxide adduct or ethylene oxide adduct is used. In this case, a trifunctional compound such as trimellitic acid, glycerin, or trimethylolpropane may be further used to form a branched or crosslinked polyester. Among them, aromatic polyester containing a bisphenol component in the main chain skeleton is extremely suitable as a binder material of the present invention because the glass transition temperature can be suitably controlled within the above temperature range when the number average molecular weight is limited to 10,000 or less. Can be used for Further, the acid value and hydroxyl value are not particularly limited, but approximately 60 or less is usually easy to use. Polyester usually has -COOH at the end of the molecular chain.
group and -OH group. These functional groups may be used as binding materials in the form of modified polyesters, block copolymers containing polyesters, or graft copolymers by condensation reactions, ionic reactions, polymer reactions, etc. In the case of unsaturated polyester, it may be used as a binding material as a modified or graft copolymer containing polyester by utilizing the double bonds within the molecule. For example, stearic acid, fatty acids such as stearyl alcohol, higher alcohols, etc.
It is also possible to modify by reacting COOH or -OH groups, by reacting with isocyanates or amines, or by reacting with silicone compounds, epoxies, phenols, etc. In addition, it can be further condensed with an aliphatic polyester mainly having crystallinity to form a block copolyester, or by utilizing double bonds in the molecular chain, styrenes such as styrene, α-methylstyrene, etc. A graft copolymer containing polyester can be obtained by polymerizing one or more types of vinyl polymerizable monomers such as methacrylic esters such as methyl methacrylate and butyl acrylate, and acrylic esters. Furthermore, zinc acetate, zinc oxide, etc. can be added to form an ionic crosslink with the terminal carboxylic acid. The mold release substance added as a binding material component together with the polyester resin of the present invention has a melting point measured by differential scanning calorimetry (DSC) or a softening point measured by a ring and ball method of 50°C or more and 200°C or less, more preferably It is an organic substance or an organic/inorganic low molecular weight polymer that is solid at room temperature of 60°C or more and 150°C or less, and it is a substance with relatively low surface energy that rapidly becomes a low viscosity liquid when it exceeds its melting point or softening point. If the melting point/softening point is below 50°C, it will lack stability during storage and use, and if the melting point is above 200°C,
Almost no additive effect is observed with respect to the thermal energy applied in a normal thermal recording method. In the temperature range of 100 to 180℃, the melt viscosity is approximately
10 poise or less, preferably about 1 poise or less, low viscosity that rapidly decreases and/or critical surface tension of about 40 dyn/cm or less, more preferably about
A substance having a low surface energy of 30 dyn/cm or less is effective as a mold release substance. Specifically, higher fatty acids such as palmitic acid and stearic acid, fatty acid metal salts such as zinc stearate, fatty acid esters or partially saponified products thereof, fatty acid derivatives such as fatty acid amides,
Higher alcohols, derivatives of polyhydric alcohols such as esters, waxes such as paraffin wax, carnauba wax, montan wax, beeswax, wood wax, candelilla wax, etc., and waxes with a viscosity average molecular weight of about 1,000 to about 10,000. Low molecular weight copolymers of polyolefins such as low molecular weight polyethylene, polypropylene, polybutylene, olefins, α-olefins and organic acids such as maleic anhydride, acrylic acid, methacrylic acid, vinyl acetate, etc.
Low molecular weight oxidized polyolefins, halogenated polyolefins, lauryl methacrylate, stearyl methacrylate, etc., methacrylic esters with long alkyl side chains, acrylic esters or acrylic esters with perfluoro groups, methacrylic esters alone or styrenes, etc. Copolymers with vinyl monomers, low molecular weight silicone resins such as polydimethylsiloxane, polydiphenylsiloxane, silicone-modified organic substances, and cationic substances such as ammonium salts and pyridinium salts having long-chain aliphatic groups. surfactant,
Alternatively, one or more types of perfluoro surfactants such as anionic and nonionic surfactants having long-chain aliphatic groups can be selected and used. These mold-releasing substances melt when heated and, due to their low cohesive force and/or low surface energy effect, can be used as main binding materials within the thermal ink material or at the interface between the thermal ink material and the support. By reducing the excessive cohesive force and adhesion between the molecules of the polyester resin of the invention and/or the interface between the polyester resin of the invention and the support, it is possible to apply lower energy, improving recording sensitivity, image quality, especially resolution, etc. . However, since many of the releasing substances are crystalline materials, if they are added in excess, the crystals cause light scattering, deteriorating transparency and, in particular, color reproducibility, so it should not be added in excess of what is necessary. Furthermore, since the ink has a low viscosity and/or a low surface energy, the fixability of the ink to a recording medium such as paper may deteriorate, or the image may spread and the resolution may be reduced. On the other hand, if the amount added is small, it cannot effectively perform its function. Therefore, the weight ratio of the polyester resin of the present invention and the releasing substance in the thermal ink binding material is approximately
When used in the range of 70:30 to about 99:1, particularly preferably about 80:20 to about 95:5, the thermal ink material of the present invention most effectively achieves its purpose, especially without deteriorating color reproducibility. I can do it. Of course, even if the amount of the polyester resin of the present invention is reduced to 70% by weight or less in the binder material, it can be put to practical use as a thermal ink, but as described above, the image quality tends to deteriorate significantly. Further, when used as a color thermosensitive recording material for pictorial full color reproduction, particular attention must be paid to the compatibility between the polyester and the releasing substance. If the compatibility or dispersibility of both is poor,
Alternatively, if the refractive index is significantly different from that of the release material, or if the release material is crystalline and has a large microcrystal diameter, color reproduction will be poor. Therefore, as mentioned above, - present at the terminal or side chain of the polyester resin constituent molecules of the present invention
By utilizing active groups such as COOH groups, -OH groups, and unsaturated bonds, and the active groups in the release material, uniform dispersion and compatibilization of the two can be promoted through functional group interaction.
Furthermore, by actively causing the active groups to react with each other, it is possible to improve the sensitivity, sensitivity unevenness, and transparency of the ink material. Furthermore, it is also effective to perform fine dispersion or even grafting of the polyester resin of the present invention or other binder resin-like materials by co-condensation polymerization or co-synthesis in the presence of a releasing substance. be. In addition, when the mold release material dispersed in the binder resin is crystalline, the crystal diameter of the mold release material is 1/2 or less of the wavelength of visible light, that is, 0.3 μm or less, particularly 0.2 μm.
It is preferable to use the following. As the binder component, if necessary, styrene such as styrene, vinyltoluene, α-methylstyrene, 2-methylstyrene, chlorostyrene, vinylbenzoic acid, sodium vinylbenzenesulfonate, aminostyrene, etc. Derivatives, homopolymers and copolymers of substituted products, methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, hydroxyethyl methacrylate, and methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, etc. Acrylic esters and dienes such as acrylic acid, butadiene and isoprene, acrylonitrile, vinyl ethers, maleic acid and maleic esters, maleic anhydride, cinnamic acid, vinyl chloride, vinyl acetate and other vinyl monomers alone Alternatively, a copolymer with other monomers can be used. Of course, even in the case of the vinyl resin, a polyfunctional monomer such as divinylbenzene may be used as a crosslinked polymer. Furthermore, using polycarbonate, polyamide, epoxy resin, polyurethane and urethane compounds, silicone resin, fluorine resin, phenol resin, terpene resin, petroleum resin, hydrogenated petroleum resin, alkyd resin, ketone resin, cellulose derivative, etc. Good too. When these polymers or oligomers are used in the form of copolymers, the copolymers may be not only random copolymers but also alternating copolymers, graft copolymers, block copolymers, mutual copolymers, etc. A copolymerization mode such as an interstitial copolymer can be appropriately selected and used. In addition, when using a mixture of two or more types of polymers or oligomers, in addition to mechanical mixing such as melt mixing, solution mixing, or emulsion mixing, coexistence polymerization, multistage polymerization, etc. may be used when polymerizing the polymer or oligomer components. may be mixed. The heat-sensitive ink material of the present invention can sufficiently achieve its purpose by using only the polyester resin of the present invention and the releasing substance as binders, but if necessary, oils and liquid plasticizers may also be used. may be added and mixed. In addition, plasticizers that are solid at room temperature, charge control and/or inhibitors, conductive agents, antioxidants, thermal conductivity improvers, magnetic materials, ferroelectric materials, preservatives, fragrances, anti-blocking agents, reinforcing fillers. ,Release agent,
A foaming agent, a sublimating substance, an infrared absorbing agent, etc. may be added inside or outside the heat-sensitive ink material. However, from the viewpoint of image quality, it is preferable that the polyester resin component of the present invention accounts for about 50% or more in volume concentration of all binder material components. Colorants include black dyes and pigments such as carbon black, oil black, and graphite; CI Pigment.
CIPigment Yellow 1, CIPigment Yellow 3, CIPigment Yellow 74, CIPigment Yellow 97, CIPigment 98, etc., acetoacetate arylamide monoazo yellow pigments (Fast Yellow series); CIPigment Yellow 12, CIPigment Yellow 13, CIPigment Yellow
Acetoacetate arylamide disazo yellow pigments such as CISolvent Yellow 19, 77, 79, CI
Yellow dye such as Disperse Yellow 164; CIPigment
Red 48, Red 49:1, Red 53:1, Red 57:1, Red 81,
122, 5 grade red or red pigment; CISolvent
Red dyes such as Red 52, Red 58, Red 8; CIPigment
Blue 15: Blue dyes and pigments such as tertiary copper phthalocyanine and its derivatives and modified products; or colored or colorless sublimable dyes, etc., conventional printing inks,
Well-known dyes and pigments can be used for other coloring purposes. These dyes and pigments may be used alone or in combination of two or more. Of course, it can be mixed with extender pigments and white pigments,
You may also adjust the color tone. Furthermore, in order to improve the dispersibility of the binder component, the surface of the colorant may be treated with a surfactant, a coupling agent such as a silane coupling agent, or a polymer material, or a polymer dye or polymer graft pigment may be used. It's okay. The heat-sensitive transfer recording material of the present invention is formed by placing a heat-sensitive ink material, which is a mixture of the polyester resin of the present invention, a releasing substance, a colorant, and, if necessary, the various additives described above, on a support. Ru. The thermal ink materials are mixed by forming a solution and/or dispersion emulsion in a solvent and/or dispersion medium that can dissolve and/or stably disperse the binder material, and mixing and dispersing using a ball mill, sand mill, attritor, three-roll mill, etc. It can be prepared in a machine. Alternatively, the mixture may be melt-mixed using a heated triple roll, heated pressure kneader, Banbury mixer, etc., without using any solvent or the like. Furthermore, the polyester resin of the present invention, which is the main binding material, may be synthesized in the presence of colorants, additives, etc., and used as a thermal ink material. The heat-sensitive ink material thus prepared is coated and printed on a support by a solution and/or melt coating method using a gravure coater, a wire bar, or the like. Alternatively, the heat-sensitive ink material may be powdered by a spray drying method, a pulverization method, or the like, and then powder coated onto a support by an electrostatic coating method or the like. in this case,
After powder coating, heating, pressurization, solvent treatment, etc. may be further performed as necessary to fix the heat-sensitive powder ink on the support before use. As the support, polyesters such as polyethylene terephthalate, polyimides and imide copolymers, fluorine polymers, plastic films such as polypropylene, thin sheets such as capacitor paper, and films are conveniently used. These sheets, films, or rolls are used with the addition of thermal property modifiers, mold release agents, antistatic agents, conductive agents, and reinforcing agents to improve thermal conductivity, thermal stability, etc. It's okay. In addition, when recording is performed using a thermal head or the like, silicone-based or fluorine-based compounds, a resin layer, a crosslinked polymer layer, A metal layer, a ceramic layer, etc. may also be provided.
Furthermore, the above-mentioned film internal additives may be added to the outer layer. The surface of these supports may be smooth or may be provided with irregularities, grooves, etc. Moreover, it may be porous. Alternatively, an electrothermal conversion element or a photothermal conversion element having a structure similar to that of a thermal head may be directly used as the support, and a heat-sensitive ink layer may be provided thereon. The thickness of the support film or sheet and the thickness of the heat-sensitive ink layer may be appropriately selected depending on the application, but in general, support thicknesses of about 1 μm to about 200 μm are easy to use. In order to improve resolution, a thickness of approximately 1 μm to approximately 10 μm is preferred. Thermal ink layer is 0.5μ
It is easy to use if it is set in the range from about m to about 50 μm depending on the purpose, and usually from about 1 μm to about 20 μm. An intermediate layer for controlling adhesion may be disposed between the thermal ink layer and the support, or the thermal ink layer itself may be a multilayer coating layer of multiple types of thermal ink materials with different physical properties, or multiple types of thermal ink materials with different physical properties may be coated within a plane. The ink material may be divided and coated. The heat-sensitive recording material formed in this way is heated in response to the applied signal by means such as a thermal head, laser, flash light, or direct application of an electric signal, and then applied to a recording medium such as paper or film. ,
The heat-sensitive ink material is transferred and recorded by being ejected in a contact state or in a non-contact state. In order to improve recording properties, it is also possible to use not only mechanical forces such as pressurization and foaming, but also electric fields, magnetic fields, ultrasonic waves, solvents, etc. [Examples] Hereinafter, the present invention will be explained with reference to Examples and Comparative Examples, but the present invention is of course not limited to these Examples. In addition, in the following examples, parts represent parts by weight unless otherwise specified. Comparative Example 1 A thermal ink material having the following composition was melt-mixed at 100° C. and then kneaded using a three-roll mill. Parafine wax (melting point = 69℃) 85 parts Softening agent (lubricating oil) 5 parts Colorant (one of the 3 pigments below) 10 parts Colorant: For cyan ink: CIPigment Blue
15:3 For magenta ink: CIPigment Red
57:1 For yellow ink: CIPigment Yellow
12 The three color thermal ink materials obtained above were
7.5μ thick plate placed on a hot plate heated to ℃
The thickness of the thermal ink layer on the polyimide film is
It was coated with a wire bar to a thickness of 2.5 μm to obtain a heat-sensitive recording material. Comparative Example 2 Using the same coloring agent as in Comparative Example 1, heat-sensitive ink materials in three colors of cyan, magenta, and yellow having the following compositions were kneaded in a ball mill at room temperature for 40 hours to create.

[Table] The thickness of the three color thermal ink materials obtained above
The heat-sensitive ink was coated on a 7.5-μm polyimide film using a wire bar so that the thickness of the heat-sensitive ink layer after drying was 2.5 μm to obtain a heat-sensitive recording material. Example 1 Using the same coloring agent as in Comparative Example 1, heat-sensitive ink materials in three colors of cyan, magenta, and yellow having the following compositions were kneaded in a ball mill at room temperature for 40 hours to prepare.

[Table] The three color thermal ink materials obtained above were coated on a 7.5 μm thick polyimide film using a wire bar in the same manner as in Comparative Example 2 so that the thermal ink layer thickness after drying was 2.5 μm. , and was used as a heat-sensitive recording material. The table below shows the results of a comparative evaluation of typical recording properties of these heat-sensitive recording materials using an FXP-6 heat-sensitive transfer printer manufactured by Fuji Xerox Co., Ltd.

〔Effect of the invention〕

The heat-sensitive recording material of the present invention is particularly excellent in color image reproducibility, recording sensitivity, transferability, fixing performance, and resolution on a transfer material. The amorphous polyester used in the present invention differs from crystalline wax, which is a binder conventionally used in heat-sensitive recording materials, by using the polyester resin of the present invention as a binder. The binding layer of the heat-sensitive recording material of the present invention exhibits extremely good transparency because the light scattering that occurs when using the heat-sensitive recording material is completely eliminated or can be controlled to a substantially problem-free level. In particular, for the purpose of obtaining clear color images, especially pictorial color reproduction images, by overlapping recording of ink materials several times, for example, magenta, yellow, and cyan ink materials are overlaid to create secondary or tertiary colors. When the heat-sensitive ink material of the present invention is used as an ink material for at least the upper layer, its transparency is good, so that the reflected light from the lower ink layer is also reflected by the characteristics of the pigment itself. There is no color difference from the desired secondary or tertiary color, and the use of a polymeric material as a binder is considered to be disadvantageous in terms of recording sensitivity compared to conventional wax-based colors. However, in the present invention, by combining a specific amorphous polyester and a release material, excessive cohesive force and adhesive force at the interface between the amorphous polyester and the support can be reduced, and wax-based thermal recording Recording sensitivity equivalent to that of the material can be obtained. The amorphous polyester resin used in the present invention usually has -COOH and -OH groups at the molecular chain terminals, but these functional groups are hydrogenated on the support supporting the thermal ink material or on the transfer material. This causes bonding, which greatly contributes to the film formability of the heat-sensitive ink material on the support, and contributes to good transferability on the transfer material. It also exhibits sufficient fixability compared to conventional waxes using low melting point crystalline waxes. In addition, the polyester resin of the present invention can supply ink material onto the transfer material according to the applied energy applied to the heat-sensitive ink material due to its gentle melting properties, which improves the continuous tone reproducibility of the transferred image. Are better. Furthermore, when a certain amount of a mold release agent is added, excessive adhesive force and cohesive force at the interface between the polyester resin of the present invention and the support are reduced without substantially reducing the transparency of the polyester resin of the present invention, resulting in good recording sensitivity. , has resolution.

Claims (1)

[Claims] 1. In a recording material in which a heat-melting thermal ink material layer is provided on a support, the thermal ink material has a glass transition temperature of 40°C or higher and a number average molecular weight of 10,000.
The main components are a transparent polyester resin that does not have a clear melting point, a coloring agent, and a mold release substance, and the weight ratio of the polyester resin and the mold release substance is from 70:30 to 99: 1. A heat-sensitive recording material characterized by: