JPH0741745B2 - Thermal transfer material and thermal transfer recording method using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat-sensitive transfer material used for thermal transfer recording, and more specifically,
The present invention relates to a heat-sensitive transfer material and a heat-transfer recording method capable of obtaining excellent recording even if the amount of the heat-sensitive transfer material used is reduced.

[Conventional technology]

In addition to the general features of the thermal recording method that the device used is lightweight and compact, there is no noise, and it is excellent in operability and maintainability, the thermal transfer recording method does not require color-developed processed paper, It has excellent durability and is widely used recently.

This thermal transfer recording method uses a thermal transfer material obtained by coating a thermal transfer ink layer formed by dispersing a coloring material in a heat-fusible binder on a generally sheet-shaped support. The thermal transferable ink layer is superposed so as to contact the recording medium, and heat is supplied from the base material side by the thermal head to transfer the melted ink layer to the recording medium.
The transfer recording image is formed on the recording medium according to the heat supply shape (pattern).

[Problems to be solved by the invention]

In the conventional thermal transfer recording, the thermal transfer ink is almost completely transferred from the thermal transfer material to the recording medium by one application of heat, so that it is disposable, the running cost is high, and the used thermal transfer material is secret. I was afraid that it would leak.

On the other hand, as in JP-A-57-83471, JP-A-58-201686, and JP-B-62-58917, a thermal transfer material having a relative speed is provided between the thermal transfer material and the recording medium. A recording method for reducing the usage amount (hereinafter referred to as double-density recording) has been proposed. However, this recording method has conventionally had some problems as follows.

The first problem is that scumming occurs (unnecessary ink transfer occurs on a recording medium such as paper).

This occurs because the double-dense recording causes the thermal transfer material and the recording medium to slide, so that the ink layer of the thermal transfer material is scraped off the surface of the recording medium and transferred to the entire surface of the recording medium.

As a measure against scumming, Japanese Patent Application Laid-Open No. 60-178088 proposes a heat-sensitive transfer material in which an overlayer containing no colorant is provided on the ink layer.

A second problem is that an unwanted whisker-like transfer, that is, so-called tailing occurs at the end portion of the transferred ink layer in the head running direction.

It is presumed that this is excessive ink cohesive failure except for the ink layer that has been applied with heat.

As a measure for vignetting transfer, it is described in Japanese Patent Application No. 1-25278 filed by the applicant earlier.

In the above publication, a thermal transfer ink in which a coloring material is dispersed in a hot-melt binder composed of an ethylene-vinyl acetate copolymer and wax is used, and not only the vignetting transfer is achieved by setting the breaking strength to a specific range. Also, the first problem, that is, soiling is prevented and solved.

A third problem is that the thermal transfer material causes curling and ink drop.

Particularly in the heat-sensitive transfer material used for double-density recording, most of the ink in the heat-transferable ink layer does not transfer to the recording medium by one application of heat, but gradually transfers to the recording medium by applying heat multiple times. There must be. Further, the obtained recorded image has a constant density,
For example, it is necessary to obtain a reflection density of 1.0 or more.

As a result, the coating amount or coating thickness of the heat transferable ink layer coated on the support must be increased as compared with the conventional thermal transfer material, and the thickness of the support is greatly increased. The ink thickness exceeds this value, curling occurs, and ink is also dropped, which is inconvenient in handling the heat-sensitive transfer material.

A fourth problem is that it is difficult to homogenize the heat transferable ink layer when manufacturing the heat sensitive transfer material.

Generally, a so-called hot melt method or a solvent coating method in which the ink is dissolved or dispersed in an organic solvent or water and applied and dried is used as a method for forming a heat transferable ink layer applied on a support.

Since the thermal transfer material used for double-density recording sets the breaking strength of the thermal transfer ink layer within a specific range, the resin content is higher than the conventional thermal transfer property, so the former hot melt method melts. The viscosity is too high to be applied.
Also in the latter solvent coating method, when the heat-meltable binder is dispersed in the organic solvent or water, the control of the breaking strength must be finely controlled under the drying conditions, resulting in extremely low manufacturing efficiency.

From the above, it is most suitable to use a solvent-coating method using a coating ink in which a heat-meltable binder is dissolved in an organic solvent.

However, waxes contained in the heat-fusible binder have poor solubility in organic solvents, and the coating ink must be heated to a relatively high temperature, resulting in a problem in workability. In addition, when not heated, waxes were broken out, and it was difficult to form a uniform thermal transfer ink layer having a predetermined breaking strength.

The fifth problem is that so-called sticking occurs due to the thermal transferable ink layer transferred to the recording medium not being cohesively destroyed in the ink layer.

As a result, the transfer of the heat-sensitive transfer material or the transfer of the recording medium becomes irregular, the ink transferred to the recording medium becomes non-uniform, and the sharpness, density, and uniformity of density of the recorded image deteriorate.

Furthermore, in the worst case, the thermal transfer material will be broken.

A sixth problem is that it is difficult to obtain a recorded image corresponding to a fine dot shape, so-called poor dot reproducibility and poor transferability.

The seventh problem is the poor cuttability of the end portion of the recorded image in the head traveling direction. It is estimated that this is due to the cohesive force of the entire heat transferable ink layer after the application of heat.

The present invention has been made in view of the above circumstances, and even with double-density recording, background stains, trailing of the trailing edge of the recorded image, and sticking do not occur, and transferability is good and sharp and sharp,
An object of the present invention is to provide a heat-sensitive transfer material and a heat-sensitive transfer recording method which can obtain a recorded image having a uniform density and which does not curl or drop ink.

[Means for Solving the Problems]

The heat-sensitive transfer material of the present invention is a heat-sensitive transfer material comprising a support and a heat-transferable ink layer comprising a heat-meltable binder and a colorant, wherein the heat-meltable binder is an isocyanate polymer of a higher fatty acid pentaerythritol ester. , And optionally containing a higher fatty acid polyhydric alcohol ester, the content of the isocyanate polymer, or the content of the isocyanate polymer and the higher fatty acid polyhydric alcohol ester combined is 20 with respect to the binder. It is characterized by being ~ 75% by weight.

Further, the heat-sensitive transfer recording method of the present invention uses the above-mentioned heat-sensitive transfer material, and the distance that the heat-sensitive transfer material moves with respect to the recording head is more than the distance that the recording medium moves with respect to the recording head within the same time. Is characterized by being shorter.

Hereinafter, the present invention will be described with reference to the drawings.

In the following description, "%" and "parts" representing the quantitative ratio are based on weight unless otherwise specified.

As shown in FIG. 1, the heat-sensitive transfer recording method (double-density recording method) using the heat-sensitive transfer material of the present invention is carried out by superimposing the heat-sensitive transfer material 1 of the present invention and a recording medium 2 such as paper, and thermal recording. By heating the recording head 3 such as a head, the thermal transferable ink of the thermal transfer material 1 is transferred to the recording medium 2 to obtain a recorded image. The thermal transfer material 1 and the recording medium 2 include a capstan roller 12, a pinch roller 13 and a platen roller 11.
By the rotation of and, the recording medium 2 is continuously moved in the directions of arrows A and B, and recording is performed on the recording medium 2 one after another. The capstan roller 12 and the pinch roller 13 are driven by a motor 14, and the platen roller 12 is driven by a motor 15. The conveyed heat-sensitive transfer material 1 is wound by a winding roller 10 driven by a motor 14. A spring 16 presses the recording head 3 against the platen roller 11 via the thermal transfer material 1 and the recording medium 2.

In FIG. 1, the thermal transfer material 1 and the recording medium 2 are moving in the same direction, but as shown in FIG. 2, the recording medium 2 is conveyed in the direction opposite to the arrow B direction to perform thermal transfer. The material 1 and the recording medium 2 may be moved in opposite directions.

Now, in this heat-sensitive transfer recording method, there is a relative speed between the heat-sensitive transfer material 1 and the recording medium 2. In the case of the example shown in FIG. 11, the head 3 does not move, and the thermal transfer material 1 moves slower than the recording medium 2. That is, when the distance over which the thermal transfer material 1 moves and the distance over which the recording medium moves over the same time period are compared, the moving distance of the thermal transfer material 1 is shorter. As a result, in this recording method, recording is performed as shown in FIGS.

As shown in FIG. 3, when the width of the heating element 3a of the recording head 3 in the heat-sensitive transfer material feed direction (direction of arrow A) is 1, the first heat application is applied to the unused heat-sensitive transfer material 1 at all. (Fig. 3). The heat-sensitive transfer material 1 comprises a support 1a and a heat-transferable ink layer 1b provided on the support 1a.

However, when the second heat is applied, the recording medium 2 is moved in the direction of arrow B, while the thermal transfer material 1 is 1 / n with respect to the recording head 3 (N = 5 in FIG. 3). The value of N depends on how many times the same portion of the thermal transfer material 1 can print.) Therefore, the [l- (l / N)] portion of the thermal transfer material 1 has already been applied with heat once. The part will be used again (Fig. 4).

When heat is continuously applied in the horizontal direction in this way, the heat-sensitive transfer material that receives heat from the second time onwards is unused only at 1 / N, and then the number of times is 1 / N each. The heat has already been applied (FIGS. 4 to 6). In other words, the thermal transfer material is in the same state as when the same place was used N times,
Moreover, it moves while rubbing the surface of the recording medium.

In the above example, the thermal transfer material 1 is moved by l / N with respect to the recording head 3 by the second and third application of heat, but it is moved by less than 1 or by 1 / N or more. In that case, the thermal transfer material 1 is saved. The above N is 2 to 10, and further 3
~ 8 are preferred.

In the above description, an example in which the recording head 3 does not move is shown. However, even when the thermal head 3 moves, the moving distance of each of the thermal transfer material 1 and the recording medium 2 is recorded.
If the distance from the recording head 3 is set with reference to, it can be considered in the same manner as in the example described with reference to FIGS. In other words, according to the thermal transfer recording method of the present invention, it is more preferable than the distance that the recording medium 2 moves with respect to the recording head 3 within the same time.
The distance that the thermal transfer material 1 moves with respect to the recording head 3 is shorter.

As is clear from the above description, the heat-sensitive transfer material 1 of the present invention is applied with heat from the heating element 3a while sliding on the recording medium such as paper to form a recorded image on the recording medium 2. Therefore, the above-mentioned background stain, trailing of the trailing edge of the recorded image, and sticking are likely to occur, and it is difficult to obtain a recorded image with good sharpness, good transferability, and uniform density. When curled, various inconveniences are likely to occur.

The heat-sensitive transfer material of the present invention contains an isocyanate polymer of a higher fatty acid pentaerythritol ester as a wax component of a heat-meltable binder and, if necessary, a higher fatty acid polyhydric alcohol ester, and these are 20 to 75 with respect to the total amount of the binder. It is the one containing wt%.

Hereinafter, the isocyanate polymer of higher fatty acid pentaerythritol ester will be described in detail.

The polymer is obtained by reacting a higher fatty acid pentaerythritol ester with an isocyanate compound.

Examples of the higher fatty acid that constitutes the ester include capric acid, undecyl acid, lauric acid, tridecyl acid, myristic acid, pentadecyl acid, palmitic acid, heptadecyl acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, and serotonin. Saturated fatty acids such as acids, heptacosanoic acid, montanic acid, melissic acid, laxeric acid,
Acrylic acid, crotonic acid, isocrotonic acid, caproreic acid, undecylenic acid, oleic acid, elaidic acid, cetoleic acid, erucic acid, brassic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid, swash acid, nisin acid, propiolic acid Unsaturated fatty acids such as stialol acid, branched fatty acids such as isovaleric acid, malvalic acid, sterulic acid, hydnocarbic acid, cyormoogulic acid, alicyclic fatty acids such as gorlinic acid, sabinic acid, iprolic acid, yarapinolic acid Oxygen-containing fatty acids such as uniperic acid, ricinoleic acid, ferronic acid and cerbronic acid can be used, and fatty acids having a melting point of 20 ° C. or higher and a carbon number of 10 to 30 can be preferably used.

Pentaerythritol is used as the alcohol.

The higher fatty acids may be used alone or in combination of two or more.

The ester must be reactive with the isocyanate compound. That is, it must have a carboxyl group derived from fatty acid or a hydroxyl group derived from pentaerythritol as active hydrogen. When the fatty acid used does not have a carboxyl group, the ester is converted to a monoester, diester or triester and is subjected to reaction with an isocyanate compound. Monoester, diester, triester alone or 2
It is also possible to use seeds and mixtures of three.

Examples of the isocyanate compound include monoisocyanates such as methyl isocyanate, ethyl isocyanate, n-propyl isocyanate, n-butyl isocyanate, octadecyl isocyanate and polymethylene polyphenyl isocyanate, 2,4-tolylene diisocyanate and 4,4'-diphenyl methane. Diisocyanate, dianisidine diisocyanate, metaxylene diisocyanate, 1,5-naphthalene diisocyanate, trans vinylene diisocyanate, N, N '(4,4'-dimethyl-3,
3'-diphenyldiisocyanate) Urethion, 2,6-
Diisocyanates such as diisocyanate methylcaproate, triphenylmethane triisocyanate, tris (4-phenylisocyanate thiophosphate) 4,
Various isocyanates of triisocyanates such as 4 ', 4 "-trimethyl-3,3', 3" -triisocyanate-2,4,6-triphenylcyanurate can be used. Particularly, diisocyanate and triisocyanate are preferable, and aromatic type is more preferable.

The reaction between the ester and the isocyanate can be carried out according to a usual method by employing a heating and stirring operation. If the heating temperature is too high, coloring of the obtained product becomes remarkable, and if it is too low, the reaction time becomes long.
It is desirable to select the range of ~ 150 ° C. Further, the above reaction can be allowed to proceed relatively quickly at a lower temperature by using a metal salt catalyst such as stannic chloride, ferric chloride, potassium oleate and dibutyltin dilaurate. It is suitable that the reaction time is usually 0.5 to 5 hours.

The amount of isocyanate used in the above reaction is appropriately selected depending on the type of each raw material used, reaction conditions, etc., but is usually about 0.1 to 40% by weight, preferably about 0.1
It is preferably selected from the range of from 30 to 30% by weight, in which the desired polymerization reaction proceeds and wax can be produced.

The wax obtained as described above exhibits good solubility in organic solvents, particularly toluene, xylene, benzene, etc.
It is possible to reduce workability during production of the heat-sensitive transfer material, that is, to reduce the amount of volatile solvent by heating the coating ink, and since there is no deposition of waxes, a uniform heat-transferable ink layer can be formed extremely efficiently.

Furthermore, when the wax is used, the curl of the heat-sensitive transfer material is extremely small and the heat-sensitive transfer material is easy to handle. It is presumed that this is because the volume shrinkage ratio of the waxes from the molten state to the solidified state is relatively small.

The heat-meltable binder of the present invention is effective as a wax component in addition to the above-mentioned isocyanate polymer of higher fatty acid pentaerythritol ester, in combination with higher fatty acid polyhydric alcohol ester, if necessary.

Examples of the higher fatty acid polyhydric alcohol are polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol,
Dipropylene glycol, polypropylene glycol,
Trimethylene glycol, butanediol, pentanediol, hexylenediol, octylene glycol,
Glycerin, trimethylolpropane, pentaerythritol, dipentaerythritol, 1.3-butylene glycol, glycerin monoallyl, (4- (hydroxyethoxy) phenol) propane, sorbitol, sorbit, neopentyl glycol, trishydroxyethyl isocyanurate, bisphenol , Hydrogenated bisphenol, bisphenol glycol ether, various epoxies (eg, triglycidyl isocyanurate) and the like are used.

The higher fatty acid pentaerythritol ester used in combination with the above isocyanate polymer is effective for adjusting the minute melting point or melt viscosity of the wax component, and thereby it is possible to change the characteristics of the heat transferable ink in various ways.

The amount of the above ester mixed is preferably 50% or less, more preferably 40% or less, based on the total amount of the heat-meltable binder.
More preferably, it is 35% or less. If it exceeds 50%, the solubility of the wax component in the solvent becomes poor, so that the workability is deteriorated and curling is likely to occur.

The isocyanate polymer or a mixture of the isocyanate polymer and higher fatty acid polyhydric alcohol ester (these are collectively referred to as wax main components) is 20 to 75% by weight, more preferably 30 to 65% by weight based on the total amount of the binder. It is contained by weight%. If it is less than 20% by weight, the tensile strength of the heat transferable ink layer becomes too large, the viscosity at the time of melting becomes high, the applied heat energy increases, and the thermal head, which is a heat source, is easily damaged. Alternatively, when the thermal energy supplied is insufficient, the runnability becomes unstable due to the sticking of the heat-sensitive transfer material and the recording medium, resulting in a defective recorded image, insufficient density, and insufficient density uniformity. If it exceeds 75% by weight, a whisker-like transfer, that is, tailing and scumming are generated, which is not preferable.

The melting point of the wax main component is preferably in the range of 50 to 90 ° C, more preferably 60 to 85 ° C. 50
If the temperature is lower than ℃, the storability of the heat-sensitive transfer material is poor and the blocking is likely to occur, and if it is higher than 90 ℃, the transfer property is poor and it is disadvantageous. Also, the melt viscosity of the main component of wax is
At 100 ° C, 10 to 10 ³ cps, preferably 10 to 500 cps, and more preferably 10 to 200 cps are good.

This is because the wax main component exhibits a solvent-like effect when heated, and the viscosity of the thermal transfer ink reduces the tensile strength and cohesive force of the ink layer, making it easier to cut the entire ink layer, It is presumed that cohesive failure is likely to occur and sticking is reduced. As a result, it is presumed that the sharpness and sharpness of the recorded image are increased, and insufficient density or uniform density is achieved.

Further, the difference between the melting end temperature and the melting start temperature of the wax main component is preferably 5 to 20 ° C., more preferably 5 to 20 ° C.
15 ℃ is good.

That is, since the melting behavior is sharp, the above-mentioned decrease in viscosity of the thermal transfer ink becomes steeper, and not only sticking but also transferability can be improved.

In the above, the melt viscosity is a value measured using an E-type viscometer (Rotovisco RV-12 manufactured by Haake, rotor used: PK-I-0.3).

In the present invention, the difference between the melting point, the melting end and the starting temperature was measured as follows.

[Measurement device] Differential scanning calorimeter DSC-7 (manufactured by Perkin Elmer) [Measurement conditions] Temperature rising rate: 5 ° C / min The difference between the melting end temperature and the melting start temperature (denoted by ΔT) is as follows. Ask. As an example, Fig. 7 shows Lanox FPS-
7 shows the measurement results of No. 7 (manufactured by Yoshikawa Oil Co., Ltd.)

The point A in the figure, that is, the peak value of absorption is taken as the melting point. △ T
Is defined as the next point, where the point B (melting start temperature) and the point C (melting end temperature) of the slope of the peak and the baseline are Ti and Te, respectively.

ΔT = Te-Ti The heat-sensitive transfer material of the present invention contains a resin component in addition to the wax main component as a heat-melting binder. As the resin component, for example, polyolefin resin, polyamide resin,
Polyester resin, epoxy resin, polyurethane resin, polyacrylic resin, polyvinyl chloride resin, cellulose resin, polyvinyl alcohol resin, petroleum resin, phenol resin, polystyrene resin, vinyl acetate resin, natural Elastomers such as rubber, styrene-butadiene rubber, isoprene rubber, chloroprene rubber,
Polyisobutylene, polybutene, etc. can be used, but they have a particularly filmy property and soften well when heat is applied /
Ethylene-vinyl acetate copolymer, or ethylene-ethyl acrylate copolymer is preferable as the one to be melted, and the content of the resin component is 25 to 80 with respect to the total amount of the binder.
% By weight, more preferably 35-70% by weight, 25% by weight
If it is less than 80% by weight, so-called whisker-like transfer, that is, tailing and scumming are likely to occur, and if it exceeds 80% by weight, transferability is lowered, sticking occurs, energy is increased, and cuttability is poor, which is not preferable.

The melt flow rate thereof is preferably 150 to 800 g / 10 min, more preferably 150 to 400 g / 10 min. If the melt flow rate is less than 150g / 10min, the melt viscosity will be large and cohesive failure will be less likely to occur, and the transferability will be reduced or the applied heat energy will increase.If it is greater than 800g / 10min, tailing and scumming will occur. It will be easier. It is of course possible to adjust the melt flow rate by mixing two or more kinds. Of these, ethylene vinyl acetate copolymers are preferable, and those having a vinyl acetate content of 15 to 33% by weight are most suitable. When the content is less than 15% by weight, the solubility in an organic solvent is lowered, the viscosity of the coating ink is increased and gelation is likely to occur, and the workability during production is lowered. If it exceeds 33% by weight, tailing tends to occur, which is not preferable.

In the above, the melt flow rate and vinyl acetate content are defined in accordance with JIS K6730.

As above, the heat-meltable binder has been described in detail, if necessary, conventionally known waxes, such as natural wax, carnauba wax, candelilla wax, rice wax, plant wax such as wood wax, ceresin wax, Examples of mineral waxes such as Montan wax, and their derivatives, for example, derivatives of Montan wax include acid wax, ester wax, and partially saponified ester wax. Animal waxes such as beeswax, whale wax and lanolin and their derivatives, and petroleum waxes include paraffin wax and microcrystalline wax. In the case of synthetic wax, polyethylene wax, Fisher Tropsch wax, etc. may be contained in the binder.

Other higher fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid and behenic acid, higher alcohols such as stearyl alcohol and behenyl alcohol,
It is also possible to use together esters such as fatty acid ester of sucrose and fatty acid ester of sorbitan, and amides such as oleylamide.

In particular, in order to firmly adhere the recorded image to the recording medium, it is effective to add resins generally referred to as tacky fire.

As Tatsuki Fire, coumarone indene resin, phenol formaldehyde resin, polyterpene resin, xylene formaldehyde resin, polybutene, rosin pentaerythritol ester, rosin glycerin ester, hydrogenated rosin, hydrogenated rosin methyl ester,
One or more selected from hydrogenated rosin triethylene glycol ester, hydrogenated rosin pentaerythritol ester, polymerized rosin ester, aliphatic petroleum resin, alicyclic petroleum resin, synthetic polyterpene, pentadiene resin, etc. .

The heat-meltable binder is contained in the heat-meltable ink layer in an amount of 50 to 99% by weight, preferably 65 to 95% by weight.

As the base material of the heat-sensitive transfer material of the present invention, conventionally known plastic films and papers can be used. However, in double-density recording, heat is applied to the same position of the base material many times. A film having a high heat resistance such as a film, a polyphenylene sulphide film, a polyether ether ketone, or a condenser paper is preferable. Also, a polyester film (especially polyethylene terephthalate film, abbreviated as PET) which has been conventionally suitably used for a thermal transfer material.
When a film) is used, it is preferable to provide a material having heat resistance and slip property on the surface opposite to the ink surface as a back surface treatment. The pressure of the substrate is preferably 3 to 20 μm, more preferably 4 to 12 μm. As long as it has high strength and heat resistance, a thin one having a thickness of 3 μm or less can be used. Also, an excessively thick one is inferior in thermal conductivity, which is not preferable.

Examples of the coloring material include carbon black, nigrosine dye, lamp black, Sudan black SM, Fast Yellow G, Benzene Yellow, Pigment Yellow,
Indian Huast Orange, Irgadine Red, Paranitroaniline Red, Toluidine Red, Carmine F
B, Permanent Bordeaux FRR, Pigment Orange R, Resole Red 2G, Lake Red C, Rhodamine FB, Rhodamine B Lake, Methyl Violet B Lake, Phthalocyaning Blue, Pigment Blue, Brilliant Green B, Phthalocyanine Green. , Oil Yellow GG, Zabong Astello CGG, Kayaset Y963, Sumiplast Yellow GG, Sabong Ast Orange RR, Oil Scarlett, Smiplast Orange G,
Orazur Brown G, The Bonn Feast Scarlett C
G, Eisenspiron Red F4R, Huastogen Blue 50
07, Sudan Blue, Oil Peacock Blue, and other conventionally known coloring agents may be used alone or in combination of two or more.

The amount of the colorant contained in the ink layer is preferably 1 to 50% by weight, more preferably 5 to 35% by weight, based on the entire ink layer. If the amount of the coloring material is less than 1% by weight, the density of the recorded image will be remarkably low, and if it exceeds 50% by weight, the recording energy will be increased, or the transferability to the recording medium will be deteriorated, and stains will occur. Undesirably occurs.

In the production of the heat-sensitive transfer material of the present invention, the binder material described above is dissolved in an organic solvent such as toluene, methyl ethyl ketone, isopropyl alcohol, methanol, xylene, and the coloring material is mixed with a disperser such as a sand mill. The solvent coating method in which the solvent is sufficiently dispersed and applied on the substrate by a coating method such as bar coating or gravure coating is most suitable. However, the resin may be heated above the softening point to disperse the colorant and then applied by so-called hot melt coating. Further, the resin or colorant may be applied as a water-based emulsion by adding a dispersant such as a surfactant. It is also possible.

When applying ink to the substrate, a single color (for example, black) is applied to the entire surface
By applying the above colored ink, a monochromatic thermal transfer can be obtained. Further, ink layers of a plurality of colors (for example, cyan color ink, magenta color ink, yellow color ink, for each predetermined length in the longitudinal direction of the substrate or for each predetermined width in the width direction,
It is also possible to obtain a heat-sensitive transfer material capable of multicolor recording by repeatedly applying different colors of blue color ink, green color ink, red color ink, etc., and recording so as to perform color superposition during printing.

Although the thickness of the ink layer varies depending on the double density, for example, when n = 3 to 8, the dry coating weight is preferably 15 to 30 g / m ² , and more preferably 16 to 25 g / m ² . Ink layer thickness is 15g /
If it is less than m ² , sufficient recording density cannot be obtained in double-density recording,
When it exceeds 30 g / m ² , problems such as increase in recording energy of the heat-sensitive transfer material occur, which is not preferable.

〔Example〕

 Hereinafter, the present invention will be described more specifically by way of examples.

The following materials were dissolved and dispersed using a sand mill to obtain a coating ink, and the coating ink was coated on a backside-treated polyester film having a thickness of 6 μm using a wire bar, dried with hot air, and dried. A thermal transfer ink layer having a coating amount of 16 g / m ² was formed to obtain a thermal transfer material.

In the following, Lanox (Wakkusu manufactured by Yoshikawa Oil Co., Ltd.) is a compound obtained by addition-polymerizing tolylene diisocyanate to a compound obtained by esterifying a higher fatty acid mixture obtained by mixing behenic acid and stearic acid with pentaerythritol, and a mixture of behenic acid and stearic acid. Is a mixture of pentaerythritol and an esterified product.

On the other hand, as shown in FIG. 2, the recording material and the thermal transfer material are conveyed such that the thermal transfer material and the recording material have a relative speed by partially modifying a Canon product, the product name Canonoff Ax630. The heat-sensitive transfer material was modified so that the transport length was shorter than the transport length of the recording medium, and the evaluation machine was used. The physical conditions of this evaluation machine are as follows.

(1) The thermal head is 8 pel / mm thick film type full multi-head, and the heater size is 100 μm in the main scanning direction and 60 μm in the sub-scanning direction.

(2) The feeding amount of the thermal transfer material is larger than that of the recording medium.
It is 1/5.

(3) The feeding directions of the thermal transfer material and the recording medium are opposite.

(4) The recording speed is 25 mm / sec, and at this time, the relative speed between the recording medium and the thermal transfer material is 31.2 mm / sec.

(5) The surface heat energy of the thermal head during recording is
It is 22 mj / mm ² .

As the received image, the image of Institute of Electronics and Electronics Engineers, Facsimile Test Chart No. 2 was output as a received image on plain paper (TRW-1A Bek smoothness 220 seconds, made by Tojo Paper).

In the test chart No. 2, the evaluation of the background stain, the beard and tailing at the trailing end of the recording, the sticking, the uniformity of the density, and the transferability were mainly performed.

Evaluation criteria are based on the following.

Ground stain ○ Almost no background stain △ There is background stain, but it can be used practically × There is a lot of background stain and no practicality Cutting ability ○ Good cutting ability △ Slightly poor cutting performance, but practical use × Cutting ability Bad, no practical use Beard-like transfer So-called tailing ○ No tailing △ It is practical, but it can be used practically × Tailing is noticeable, no practicality Concentration of density (test chart Streaks in the main scanning direction at part 1) ○ Streaks are hardly observed, and the image is uniform.

△ Slight unevenness is observed, but it can be used practically. × Streaks are generated, and it cannot be said that it is a homogeneous image. (White streaks in the main scanning direction at the part) ○ No white streaks are found. △ Small white streaks are found, but practically usable × White streaks are noticeable and practically unusable Transferability (Test Chart ○ There is no chipping △ There is some chipping, but it can be used practically × Curl is noticeable and can not be used practically Curl ○ Curl is extremely small and does not feel inconvenient to handle × Curl is severe and practical Insufficient ink drop ○ Ink does not peel off when the thermal transfer material is scrubbed by hand. × Ink drops when the thermal transfer material is scrambled. Table 1 shows the evaluation results.

[Effects of the Invention] As described above, the heat-sensitive transfer material of the present invention is an isocyanate polymer of higher fatty acid pentaerythritol ester and, if necessary, higher fatty acid polyhydric alcohol ester with respect to the total amount of binder in the heat-meltable binder. Content of 20 to 75% by weight as wax component, even when used for double-density recording, background stains, beard at the trailing edge of the recorded image, so-called tailing, good cutting performance and transferability, and uniform density It is possible to obtain a recorded image having

In addition, it is possible to obtain a heat-sensitive transfer material that is extremely curl-free and has no curl or ink drop.

[Brief description of drawings]

1 and 2 are perspective views showing an example of an apparatus using the heat-sensitive transfer material of the present invention. 3 to 6 are partial side views showing an example in which the heat-sensitive transfer material of the present invention is used for double-density recording. FIG. 7 is a graph showing an example of the DSC measurement result. 1 ... Thermal transfer material 2 ... Recording medium 3 ... Recording head 3a ... Heating element

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuo Hasegawa 770 Shimonoge, Takatsu-ku, Kawasaki-shi, Kanagawa Canon Inc. Tamagawa Plant (56) Reference JP-A-61-220893 (JP, A) JP-A-63 -172687 (JP, A) JP 63-27291 (JP, A) JP 64-47588 (JP, A) JP 61-84288 (JP, A) JP 1-118484 (JP, A) ) JP-A-64-22591 (JP, A)

Claims (10)

[Claims] 1. A heat-sensitive transfer material having a heat-transferable ink layer comprising a heat-meltable binder and a colorant on a support, wherein the heat-meltable binder is an isocyanate polymer of a higher fatty acid pentaerythritol ester, and Depending on the content of the higher fatty acid polyhydric alcohol ester, the content of the isocyanate polymer, or the content of a combination of the isocyanate polymer and the higher fatty acid polyhydric alcohol ester, relative to the binder
20-75% by weight of a thermal transfer material. 2. The heat-fusible binder is selected from ethylene vinyl acetate copolymer and ethylene ethyl acrylate copolymer, and the binder is 25
The thermal transfer material according to claim 1, wherein the thermal transfer material is contained in an amount of -80% by weight. 3. The melting point of the isocyanate polymer and the melting point of a combination of the isocyanate polymer and the higher fatty acid polyhydric alcohol ester are in the range of 50 ° C. to 90 ° C. Item Thermal transfer material. 4. The melt viscosity of the isocyanate polymer at 100 ° C. and the melt viscosity of a combination of the isocyanate polymer and the higher fatty acid polyhydric alcohol ester are in the range of 10 to 1000 cps. Alternatively, the heat-sensitive transfer material of item 2. 5. The heat-sensitive transfer material according to claim 1, wherein the difference between the melting end temperature and the melting start temperature of the isocyanate polymer is in the range of 5 to 20 ° C. 6. The difference between the melting end temperature and the melting start temperature of a combination of the isocyanate polymer and the higher fatty acid polyhydric alcohol ester is in the range of 5 to 20 ° C. Item Thermal transfer material. 7. The melt flow rate of the resin component is 150 to 8
The heat-sensitive transfer material according to claim 2, which is 00 g / 10 min. 8. The resin component has a vinyl acetate content of 15 to 33% by weight.
3. The heat-sensitive transfer material according to claim 2, which is an ethylene-vinyl acetate copolymer. 9. The heat-sensitive transfer material according to claim 1, wherein the distance that the heat-sensitive transfer material moves with respect to the recording head is more than the distance that the recording material moves with respect to the recording head within the same time. A thermal transfer recording method characterized by being shorter. 10. The thermal transfer material according to claim 2, wherein the thermal transfer material is moved relative to the recording head by a distance greater than a distance over which the recording material moves relative to the recording head within the same time. A thermal transfer recording method characterized by being shorter.