JP2576061B2 - Thermal recording material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for heating a recording material in response to an applied signal by means of a thermal head, a laser, a flash light or a means for directly supplying an electric signal. The present invention relates to an image recording material that performs thermal transfer.

[Prior Art] Many methods have been proposed for a thermal recording method using a change in physical properties and a change in chemical reactivity of a material corresponding to the application of thermal energy. Above all, colorless dyes such as crystal violet lactone, fluoran type, spiropyran type and phenol compounds such as bisphenol A and other organic acids, dye coloring reaction with organic acids and inorganic acids, organic acid metal salts and organic reducing agents such as phenols, metals Recording of inks and coloring materials on paper, etc., using thermosensitive coloring recording method using thermal reaction with fluidized products, organic chelating agents, and organic sulfur compounds, and changes in thermophysical properties such as thermal fusibility and thermal sublimation In recent years, a thermal transfer recording method of transferring to a body has been actively studied, and efforts have been made for improvement. In particular, the latter thermal transfer recording method is capable of recording on plain paper, has good stability such as light fastness of recorded images, good storage stability, and has a high reliability due to a simple recording mechanism. Due to its advantages, it is actively applied to printers, facsimile machines, copiers and the like.

[Problems to be Solved by the Invention] However, the method of thermally sublimating the dye has the advantage that it can be reproduced with almost continuous gradation of density,
There are problems in recording sensitivity, storage stability of a recording medium, fixing stability of a recorded image, light resistance, and the like. In the case of a method in which the ink is thermally melted and the ink corresponding to the applied signal is transferred and recorded on paper or the like, the above problem is reduced. However, a crystalline wax having a low melting point is usually used as a binder for the heat-sensitive ink layer. Therefore, there are problems that the resolving power is reduced due to thermal diffusion in the recording medium and the strength of the transferred and fixed images is weak.

In addition, crystalline waxes have a disadvantage that it is difficult to obtain a clear color image due to light scattering of a crystalline phase.

Accordingly, an object of the present invention is to provide a thermal transfer recording material having good resolution.

Another object of the present invention is to provide a thermal transfer recording material which enables clear color reproduction.

Still another object of the present invention is to provide a heat-sensitive transfer recording material having good recording sensitivity, transfer and fixing properties.

[Means for Solving the Problems] As a result of intensive studies, the present inventors have applied a heat-sensitive ink material having a specific release material as a main binder material on a support, and further applied a main binder material thereon. By applying a heat-sensitive ink material in which the deposition component is changed from a conventional crystalline wax to a specific amorphous polymer material to form a heat-sensitive ink layer, it has been confirmed that the object can be achieved, and the present invention has been confirmed. completed.

That is, the present invention is a thermosensitive recording material comprising a support and a thermosensitive ink layer provided on one surface thereof, wherein the thermosensitive ink layer is formed by laminating a plurality of thermosensitive ink materials,
Among the plurality of thermal ink materials, the thermal ink material immediately above the support mainly includes a release material having a melting point or softening point of 50 ° C. or more and 200 ° C. or less, and the other thermal ink material has a glass transition temperature. A heat-sensitive recording material comprising an amorphous polymer having a temperature of 40 ° C. or higher as a main binder component and at least one heat-sensitive ink material containing a colorant.

In the heat-sensitive recording material of the present invention, it is preferable to use an amorphous polymer having a number average molecular weight of 10,000 or less.

 Hereinafter, the constitution of the thermosensitive recording material of the present invention will be described in detail.

Conventionally, waxes used as binder 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 copolymers thereof. And mineral oils such as spindle oil, vegetable oils such as linseed oil and tung oil, plasticizers such as dioctyl phthalate and dibutyl phthalate, higher fatty acids such as oleic acid and stearic acid, and metal salts thereof, if necessary. , Amides and other derivatives were mixed and dispersed together with dyes and pigments and applied to a thin plastic film or capacitor paper to obtain a thermal transfer recording material.

Since waxes as such conventional binder materials are crystalline, they have a relatively clear melting point in a temperature range of about 50 ° C. to about 150 ° C., and when heated above the melting point, rapidly solidify. Changes from phase to liquid phase. At a temperature about 30 ° C. higher than the melting point, the liquid becomes a low viscosity liquid of about 10 ^{−2 to} about 10 poise. On the other hand, in the case of an amorphous polymer, there is essentially no melting point, and the solid phase gradually changes from a solid phase to a liquid phase at the glass transition temperature (Tg). The viscosity change during this time is basically WL
According to F or Andrade formula, usually about 50 from Tg
Even at a high temperature of ℃, the viscosity decreases only up to about 10 ³ to 10 ⁵ poise. In the case of thermal transfer recording, the transfer and fixing sensitivity is basically governed by the melt viscosity and melt viscoelasticity of the binder material. Clearly disadvantageous.

However, the present inventors use an amorphous polymer having a specific molecular weight and Tg as a binder, and use a heat-sensitive ink material containing a release material as a binder as the lowermost layer to bind the amorphous polymer. It has been found that image quality and image stability can be significantly improved without sacrificing sensitivity by applying a heat-sensitive ink layer as a coating material on a support.

 The outline is described below together with a representative example.

In the present invention, the number average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC) method is about 10,000 or less, Tg measured by differential scanning calorimetry (DSC) method is about 40 ℃ or more, more preferably the number average molecular weight When an amorphous polymer or oligomer having a molecular weight of about 5,000 or less and a Tg in the range of about 50 ° C. to 80 ° C. is used as the adhesive material, the object can be achieved well. Tg less than 50 ° C, especially
When the temperature is lower than 40 ° C., blocking of the heat-sensitive ink material is liable to occur, resulting in lack of stability during storage and use. Also
When Tg exceeds 80 ° C, the thermal stability is good,
Since the sensitivity is reduced, it is not practical except for special uses. It was experimentally confirmed that the sensitivity also decreased when the molecular weight of the polymer was high even when the Tg was within the above range. This is presumed to be due to cohesion between molecules based on entanglement of molecular chains and the like. 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 can vary depending on the use of the thermal transfer recording material. When a binary transfer image is to be obtained as in the case of a conventional wax-based ink, the weight-average molecular weight is also about 4%.
It is desired to reduce the molecular weight distribution to not more than 10,000, more preferably not more than about 10,000. On the other hand, when the density of the gradation gradation and the multi-value transfer image are obtained by utilizing the distribution of the cohesive force between the polymer chains and the relaxation time, and the amount of the transfer ink is controlled for the purpose of performing the use repeatedly a number of times. The weight average molecular weight does not necessarily need to be reduced, and may be set to about 40,000 or more. Furthermore, the pattern of the molecular weight distribution does not necessarily need to be a shape having a single molecular weight peak, but may be a distribution shape having a plurality of molecular weight peaks. Further, a crosslinked or branched polymer component may be used in combination. However,
When the weight average molecular weight is set to about 10,000 or more, particularly 40,000 or more, sensitivity becomes disadvantageous.

The chemical composition and structure of the amorphous polymer, of course, affect the properties of the thermal ink material, but the effect is not as great as the molecular weight and Tg described above. If the molecular weight and Tg are within the above-specified ranges, it can be basically applied as the thermal ink material of the present invention.

For example, styrene and vinyl toluene, α-methylstyrene, 2-methylstyrene, chlorostyrene, vinylbenzoic acid, sodium vinylbenzenesulfonate, styrene such as aminostyrene and derivatives thereof, homopolymers and copolymers of substituted products, Methacrylates such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, and hydroxyethyl methacrylate; and acrylates such as methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate; and diene 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 or It can be used a copolymer of a monomer of.

Examples of the condensation resin include phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, hexahydrophthalic anhydride, malonic acid, succinic acid, glutaric acid, adipic acid, and sebacic acid. , Fumaric acid, itaconic acid, unsaturated dibasic acids such as tetrahydrophthalic anhydride and ethylene glycol, 1,2-propylene glycol, 1,6-hexanediol, bisphenol A, bisphenol A propylene oxide adduct,
A polyester resin obtained by polycondensation with a diol such as bisphenol A ethylene oxide adduct may be used. In this case, a branched or crosslinked polyester may be further obtained by using a trifunctional compound such as trimellitic acid, glycerin, and trimethylolpropane. Of course, in the case of the vinyl resin, a polyfunctional monomer such as divinylbenzene may be used as a crosslinked polymer. Further, polycarbonate, polyamide, epoxy resin, polyurethane, silicone resin, fluorine resin, phenol resin, terpene resin, petroleum resin, hydrogenated petroleum resin, alkyd resin, ketone resin, cellulose derivative and the like may be used. When these amorphous polymers or oligomers are used in the form of a copolymer, the copolymer is not only a random copolymer but also an alternating copolymer, a graft copolymer, and a block copolymer according to the intended use. Copolymerization modes such as coalescing and interpenetrating copolymers can be appropriately selected and used.
When two or more kinds of polymers and oligomers are mixed and used, in addition to mechanical mixing such as melt mixing, solution mixing, and emulsion mixing, polymer and oligomer components are mixed by coexisting polymerization, multistage polymerization, or the like. May be.

The releasable substance used as the binder of the thermal ink material applied first to the support has a melting point measured by differential scanning calorimetry (DSC) or a softening point measured by ring and ball method of 50 ° C.
An organic substance or an organic / inorganic low molecular weight polymer that is solid at room temperature of 200 ° C or lower, more preferably 60 ° C or higher and 150 ° C or lower, and has a relatively high surface energy that rapidly becomes a low-viscosity liquid beyond its melting point or softening point. Is a low substance. When the melting point / softening point is less than 50 ° C, the stability during storage and use is lacking. When the melting point is more than 200 ° C, the mold release effect on the thermal energy applied by the normal thermal recording method is used. Will not be exhibited. In a temperature range of about 100 to 180 ° C., the melt viscosity is about 10 poise or less, more preferably about 1 poise.
Low viscosity and / or critical surface tension such as sharply decreasing to poise or less, about 40 dyn / cm or less, more preferably about 30 dy / cm
A substance having a low surface energy of n / cm or less is effective as a releasable substance.

Specifically, for example, 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 and polyhydric alcohols Derivatives such as esters of paraffins; paraffin wax, carnauba wax, montan wax, beeswax,
Waxes such as wood wax and candelilla wax; low molecular weight polyolefins such as polyethylene, polypropylene and polybutylene having a viscosity average molecular weight of about 1,000 to about 10,000, or olefins, α-olefins and maleic anhydride, acrylic acid, methacrylic acid Low molecular weight copolymers with organic acids such as acids, vinyl acetate, etc .; low molecular weight oxidized polyolefins; halogenated polyolefins; methacrylic esters, acrylic esters, or perfluoroesters having long chain alkyl side differences such as lauryl methacrylate and stearyl methacrylate Acrylic acid ester having a group,
Copolymers of methacrylic acid esters or the like or copolymers with vinyl monomers such as styrenes; low molecular weight silicone resins such as polydimethylsiloxane and polydiphenylsiloxane, and silicone-modified organic substances; And at least one kind selected from cationic surfactants such as ammonium salts and pyridium salts, or anions having a long-chain aliphatic group, nonionic surfactants, and perfluoro surfactants.

These releasable substances are melted between the support and the heat-sensitive ink material using the upper amorphous polymer as a binder during heating,
Based on the low cohesive force and / or low surface energy effect, it is considered that recording sensitivity and image quality are improved because excessive cohesive force and adhesive force at the interface between the heat-sensitive ink layer and the support are reduced.

As described above, the inventors of the present invention apply a heat-sensitive ink material having a release material and an amorphous polymer as a binder material on a support to form a heat-sensitive ink layer. It has been found that image stability can be improved.

That is, when using only a heat-sensitive ink material using a release material as a binder resin, although recording sensitivity is advantageous,
Due to the low cohesive force and / or low surface energy, fixation to a recording medium such as paper is deteriorated, an image is widened and resolution is deteriorated, and since many release substances are crystalline materials, color reproduction is performed. Deterioration of performance.

On the other hand, when only a thermal ink material using an amorphous polymer as a binder material is used, the fixing stability, the resolution, and the color reproducibility are excellent, but the adhesive strength between the support and the thermal ink layer is large and disadvantageous in sensitivity. Become. On the other hand, on the support, a thermal ink material using a release material as a binder material is first applied, and then a thermal ink material using an amorphous polymer as a binder material is laminated and applied to form a heat-sensitive ink layer. In the configuration of the present invention, since only the function at the interface between the support and the heat-sensitive ink layer is required for the release material, the release material should be made as thin as possible, preferably 2 μm or less in dry film thickness. This reduces light scattering to a level where there is no practical problem, improves color reproducibility, and makes use of the advantages of an amorphous polymer, while adhering at the interface between the support and the thermal ink layer during heating as described above. Can be reduced to improve the recording sensitivity.

Examples of the colorant in the heat-sensitive recording material of the present invention include black dyes such as carbon black, oil black, and graphite; acetoacetic arylamide monoazo yellow pigments such as CI Pigment Yellow 1, 3, 74, 97, and 98. (Fast yellow); acetoacetic arylamide disad yellow pigments such as CI Pigment Yellow 12, 13, and 14; CISolve
Yellow dyes such as nt Yellow 19, 77, 79, CI, Disperse Yellow 164, CI Pigment Red 48, 49: 1, 53: 1, 57:
1, 81, 122, 5 and other red or red pigments; CISolve
Red dyes such as nt Red 52, 58, and 8; CI Pigment Blue 1
Blue dyes and pigments such as 5: 3 copper phthalocyanine and derivatives and modified products thereof; and dyes and pigments well known in conventional printing inks and other coloring applications such as colored or colorless sublimable dyes can be used.

These dyes and pigments may be used alone or as a mixture of two or more. Of course, the color tone may be adjusted by mixing with an extender or a white pigment. Furthermore, in order to improve the dispersibility of the binder component, the surface of the colorant is treated with a surfactant, a coupling agent such as a silane coupling agent, a polymer material, or a polymer dye or a polymer graft pigment. May be used.

In the heat-sensitive recording material of the present invention, a charge control and / or antistatic agent, a conductive agent, an antioxidant, a thermal conductivity improver, a magnetic substance, a ferroelectric substance, a preservative, a fragrance, a blocking inhibitor, Reinforcing fillers, release agents, foaming agents, sublimable substances, infrared absorbers and the like may be added to the inside or outside of the thermal ink material and used.

As the support, polyesters such as polyethylene terephthalate, polyimide and imide copolymers, fluoropolymers, plastic films such as polypropylene, thin sheets such as capacitor paper, and films are conveniently used.

These sheets, films, or rolls are used by adding a thermal property modifier, a release agent, an antistatic agent, a conductive agent, and a reinforcing agent for improving thermal conductivity, thermal stability, etc. therein. Is also good. When recording is performed using a thermal head or the like, a silicone-based or fluorine-based compound, a resin layer or a crosslinked polymer layer is provided on the side of the support in contact with the thermal head to improve heat resistance, running properties, and the like. , A metal layer, a ceramic layer, and the like. Further, the film internal additive may be added to the outer layer. The surface of these supports may be smooth, or may be provided with uneven portions, thin portions, or the like. Further, it may be porous.

The heat-sensitive transfer recording material of the present invention is obtained by laminating a plurality of heat-sensitive ink materials obtained by mixing a releasable substance or an amorphous polymer or oligomer, a colorant, and, if necessary, various additives described above on a support. It is formed by coating.

The mixing of the heat-sensitive ink material is performed by forming a solution and / or a dispersion emulsion in a solvent and / or a dispersion medium capable of dissolving and / or stably dispersing the binder material, and mixing and dispersing the mixture with a ball mill, a sand mill, an attritor, a three-roll or the like. Can be prepared on a press. In addition, without using a solvent or the like in particular, a heating type three rolls, a heating and pressing kneader,
The solvent may be mixed with a Banbury mixer or the like. Further, the amorphous polymer may be polymerized in the presence of a coloring agent, an additive, and the like to form a thermal ink material. The plurality of thermal ink materials thus prepared are sequentially applied and / or printed on a support by a solution and / or a 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 pulverizing method, or the like, and then powder-coated on a support by an electrostatic coating method or the like. In this case, after the powder coating, the heat-sensitive powder ink may be further fixed on a support by performing heating, pressurization, solvent treatment, and the like, if necessary. Furthermore, when such a heat-sensitive powder ink is prepared, the amorphous polymer is polymerized by a direct polymerization method such as a suspension polymerization method or a dispersion polymerization method in the presence of a coloring agent and an additive. To prepare a powder ink. Also, as a support,
An electrothermal conversion element or a photothermal conversion element having a structure similar to that of the thermal head may be directly used, and a thermal ink layer may be provided thereon.

The thickness of the support film and sheet and the thickness of the heat-sensitive ink layer may be appropriately selected depending on the application, but generally, the support having a thickness of about 1 μm to about 200 μm is easily used. In order to increase the resolution, the thickness is preferably from about 1 μm to about 10 μm.

The thermal ink layer has a dry coating thickness of 0.1% for each thermal ink material.
from about μm to about 50μm depending on the application, usually about 1μ
It is easy to use to set the range from m to about 20 μm.

Further, a plurality of types of ink materials having different physical properties may be dividedly coated in the plane layer.

The thermal recording material formed in this manner is
Heating in response to an applied signal by means of direct application of a laser, flash light, or electric signal, etc., and causing the recording medium such as paper or film to fly in a contact state or non-contact state Transfer recording of the heat-sensitive ink material. In order to improve the recording property, it is possible to use not only mechanical force such as pressurization and foaming but also electric field, magnetic field, ultrasonic wave, solvent and the like.

EXAMPLES Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples. In the following examples, parts are parts by weight unless otherwise specified.

Example 1 Thermosensitive ink materials (a) to (d) having the following compositions were applied on a 6 μm-thick polyester film to prepare thermosensitive recording materials 1 to 5.

[Thermal Ink Material Composition] (a) Paraffin wax (melting point = 65 ° C) 85 parts Softener (lubricating oil) 5 parts Blue pigment (CIPigment Blue 15: 3) 10 parts The above composition was melted and mixed at 100 ° C. Thereafter, the mixture was kneaded with a three-roll mill to obtain a heat-sensitive ink material (a).

(B) Ester wax (melting point = 74 ° C) 2.7 parts Nonionic surfactant 0.3 part Distilled water 97 parts The above composition is stirred and emulsified at 90 ° C to form a wax emulsion having an average wax particle diameter of 0.5 µm. (B).

(C) 18 parts of styrene / lauryl methacrylate copolymer Blue pigment (CIPigment Blue 15: 3) 2 parts Toluene 80 parts The above composition was kneaded in a ball mill at room temperature for 40 hours to obtain a heat-sensitive material (c).

(D) 18 parts of styrene / 2-ethylhexyl acrylate / lauryl methacrylate copolymer Blue pigment (CIPigment Blue 15: 3) 2 parts Toluene 80 parts The above composition was kneaded in a ball mill at room temperature for 40 hours to obtain a heat-sensitive ink material (d).

[Configuration of Thermal Recording Material] Thermal Recording Material 1 (Comparative Example 1) As shown in FIG.
On the polyester film (1) on a hot plate heated to 0 ° C., the thickness of the heat-sensitive ink layer (2) after cooling is 3 μm.
m was applied with a wire bar to obtain a heat-sensitive recording material 1.

Thermosensitive recording materials 2 and 3 (Comparative Examples 2 and 3) The thermosensitive ink material (c) or (d) was applied on a polyester film by a wire bar so that the thickness of the dried thermosensitive ink layer was 3 μm. Thermal recording material 2
(The ink material was (c)) and the heat-sensitive recording material 3 (the ink material was (d)) (see FIG. 1).

Thermal Recording Materials 4 and 5 (Example 1 and Comparative Example 4) As shown in FIG. 2, the wax layer thickness after drying the thermal ink material (b) on the polyester film (1) was 0.5 μm.
Then, the mixture was heated to 120 ° C. to melt the wax particles to form a uniform wax layer (3) and then cooled.

On the wax layer (3) formed on the polyester film (1), the thermal ink material (c) or (d) is applied with a wire bar so that the thickness of the dried ink layer (2) becomes 2.5 μm. And a thermosensitive recording material 4 (ink material of (b) and (c)) and a thermosensitive recording material 5 (ink material of (b) and (d)).

The following table shows the results of evaluating typical recording characteristics of the heat-sensitive recording materials 1 to 5 prepared by the above-mentioned formulas using a Fuji Xerox Co., Ltd. FX P-6 thermal transfer printer.

The recording characteristics were evaluated by the following method.

Recording sensitivity: Thermal head heating element size (1 / 8mm = 125
μm) Energy applied to the thermal head for recording a transfer dot corresponding to (μm) (= E) ◎; E <0.7 mJ / dot ○; 0.7 mJ / dot E <0.9 mJ / dot △; 0.9 mJ / dot E <1.1 mJ / dot ×; 1.1mJ / dot E Resolution: How to destroy Chinese characters (especially those with a large number of strokes) Transparency: Color turbidity when transferred to an OHP sheet and projected on a screen Fixing degree: Finger and As shown in the table, the conventional type (thermosensitive recording material 1) using wax as a binder for the entire ink layer is slightly superior in recording sensitivity, as shown in the table. In the case of kanji with a large number of strokes, the characters may be crushed and it may be difficult to read them, and rubbing the transferred image with a finger may cause stains around the transferred image. On the other hand, the heat-sensitive recording material 4 according to the present invention has almost the same recording sensitivity as that of the conventional type 1, and furthermore, a clear print without crushing can be obtained. Recording characteristics. In contrast, the conventional type 1 had a dark blue color, whereas a clear blue projection image without turbidity was obtained.

Further, from the relationship between the heat-sensitive recording materials 2 and 4 and the relationship between 3 and 5, the contribution of the heat-sensitive ink layer using the release agent as a binder to the improvement of the recording sensitivity was confirmed. From the relationship of 5, the contribution of the number average molecular weight and the control of the glass transition temperature was confirmed.

Example 2 Thermosensitive ink materials (e) and (f) having the following compositions were applied on a 6 μm-thick polyester film to prepare a thermosensitive recording material 6.

[Thermal ink material composition] (e) Polyester resin 16 parts Coloring agent (carbon black) 4 parts Toluene 40 parts Methyl ethyl ketone 40 parts The above composition was kneaded in a ball mill at room temperature for 30 hours to obtain a heat-sensitive ink material (e).

(F) Ester wax (melting point = 77 ° C.) 2.7 parts Nonionic surfactant 0.3 part Distilled water 97 parts The above composition was stirred and emulsified at 95 ° C. to form a wax emulsion, which was used as a heat-sensitive ink material (f).

[Configuration of Thermal Recording Material 6] The thermal ink material (f) is placed on a polyester film,
The resultant was applied with a wire bar so that the thickness of the dried wax layer was 0.5 μm, and then heated to 120 ° C. to melt the wax particles, formed into a uniform wax layer, and then cooled.
The heat-sensitive ink material (e) was laminated and coated on the wax layer with a wire bar so that the ink layer thickness after drying was 2.0 μm, to obtain a heat-sensitive recording material 6 (see FIG. 2).

When the obtained heat-sensitive recording material 6 was evaluated in the same manner as in Example 1, it was possible to record transfer dots of the same size with an applied energy (E = 0.69 mJ / dot) about 1.1 times that of Comparative Example 1. In addition, a strong print with a clear outline and no peeling of the ink even when rubbed with a finger was obtained.

Example 3 A thermosensitive ink material (g) having the following composition was coated to a thickness of 3.5 μm.
m and dried on a polyester film having a dry thickness of 0.2 μm. The colorant of the heat-sensitive ink material (e) in Example 2 was further coated with a blue pigment (CIPigment Blue).
15: 3), a red pigment (CIPigment 57: 1), and a yellow pigment (CIPigment Yellow 12) were applied so as to have a dry thickness of 2.0 μm, respectively, to obtain a thermosensitive recording material (No. 2).
See figure).

(G) 12 parts of 12-hydroxystearic acid 98 parts of methyl ethyl ketone 98 parts of the thus obtained three-color heat-sensitive recording material were evaluated for recording characteristics in the same manner as in Example 1, and were found to be extremely sharp, excellent in resolution and excellent in transparency. Three strong colors of blue, red and yellow were obtained.

Example 4 third thickness 15μm As shown, the volume resistivity of 10 ⁰ Ω · c
m) The heat-sensitive ink material (f) of Example 2 was dried and formed into a film on the aluminum surface of a support on which aluminum (5) was vacuum-deposited to a thickness of 800 A on one surface of a conductive polycarbonate film (4) having a thickness of m. The heat-sensitive ink material (e) of Example 2 was also applied as a first layer (3) by coating with a wire bar so as to have a thickness of 0.5 μm to form a first layer (3), and then as a second layer (2). The coated ink was dried with a wire bar so that the thickness of the ink layer became 5.0 μm, and dried to obtain a thermosensitive recording material.

When this thermal recording material was mounted on a prototype of an energized thermal transfer printer and recorded on various types of recording paper, the contours were extremely clear even for bond paper and plain paper (high quality paper) with low smoothness. , A strong print without peeling of the ink was obtained.

Example 5 Further, the influence on the recording sensitivity and transparency of the thickness of the heat-sensitive ink layer using a release material as a binder as the lowermost layer (first layer) was evaluated. The prescription of the heat-sensitive recording material used in the evaluation is (b), (c) and (d) described in Example 1 above. However, the heat-sensitive ink material (b) (containing a release material) Ink material as an adhesive) is applied as a first layer in various thicknesses, and then a second layer of the thermal ink material (c)
Or (d), the coating thickness after drying of the total of two layers is 3 μm
It was adjusted to become.

FIGS. 4 (a) and 4 (b) show the relationship between the recording sensitivity and the transparency of the first layer ink when the thermal ink material (c) is used for the second layer, respectively. (A)
(B) shows the same relationship when the thermal ink material (d) is used for the second layer.

Improving the recording sensitivity with the thermal ink material (b) (a thermal ink material using a release material as a binder) applied on a polyester film is sufficiently effective when the coating thickness is 0.5 μm. Simply increasing the thickness did not have the effect of improving the recording sensitivity (FIGS. 4 (a) and 5 (a)).
reference).

On the other hand, the transparency deteriorated when the coating thickness of the heat-sensitive ink material (b) was increased, and when it exceeded 1.5 μm, the transparency became almost the same as that of the heat-sensitive recording material 1 (FIGS. 4 (b) and 5 (b)). )reference).

From the above, it was found that when the coating thickness of the thermal ink material (b) was 0.5 μm, the recording sensitivity could be improved while maintaining good transparency.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing the structure of a conventional heat-sensitive transfer recording material, FIGS. 2 and 3 are cross-sectional views each showing the structure of the heat-sensitive transfer recording material of the present invention, FIGS. (B) is a graph showing the relationship between the thickness of the first layer, the recording sensitivity and the transparency of the recording material in which the first layer is composed of only a releasing material, and FIGS. 5 (a) and (b) are the same. 6 is a graph showing the relationship between the thickness of the first layer, recording sensitivity, and transparency when another ink material is used as the second layer. Symbols in the figure: 1 ... polyester film; 2 ... thermal ink layer; 3 ...
Thermal ink layer (wax layer); 4... Conductive polycarbonate film; 5... Aluminum layer; 6.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-244991 (JP, A) JP-A-61-273991 (JP, A) JP-A-62-37190 (JP, A) JP-A-62-37190 13384 (JP, A) Japanese Utility Model Showa 57-199472 (JP, U)

Claims (1)

(57) [Claims] 1. A heat-sensitive recording material comprising a support and a heat-sensitive ink layer provided on one side thereof, wherein the heat-sensitive ink layer is formed by laminating a plurality of heat-sensitive ink materials. The thermal ink material just above the body,
A melting point or a softening point is a releasing material having a temperature of 50 ° C or more and 200 ° C or less as a main binding component, and other thermal ink materials are made of an amorphous polymer having a glass transition temperature of 40 ° C or more as a main binding component. A heat-sensitive recording material, wherein one heat-sensitive ink material contains a colorant.