JPS62181185A - Thermal transfer material and thermal transfer recording method - Google Patents

Abstract

PURPOSE:To stably produce intermediate-gradation recorded images with excellent uniformity and reproducibility, by sequentially providing a layer of a first thermally transferable ink and a layer of a second thermally transferable ink having a melting point lower than that of the first ink, on a base. CONSTITUTION:A thermal transfer layer 3 provided on a base 2 comprises a layer 3a of a second thermally transferable ink having a light color tone and a layer 3b of a second thermally transferable ink having a deep color tone. Each of the inks comprises a fusible binder and a coloring agent. The first thermally transferable ink has a higher melting point of preferably 60-180 deg.C, whereas the second thermally transferable ink has a lower melting point of preferably 50-120 deg.C. A thermal transfer material with this construction is capable of giving a transfer-recorded image with an ordinary density in response to application of a relatively small quantity of energy and giving a transfer-recorded image with an intermediate gradation in response to application of a relatively large quantity of energy.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal transfer material that provides a half-tone recorded image with excellent uniformity of print density and reproducibility, and a thermal transfer recording method using the same.

11 and 3 The thermal transfer recording method, which is one of the recording methods widely used in information processing systems, generally includes a thermal transfer layer formed by dispersing a colorant in a heat-melting binder on a sheet-like base material; Alternatively, a thermal transfer material provided with a dye layer containing a heat-sublimable dye is used, and this thermal transfer material is superimposed on the recording material so that the thermal transfer layer or the dye layer is in contact with the recording material, and the thermal transfer material is Forms a transferred recorded image on the recording material according to the heat supply pattern by supplying heat from the base material side of the material using a thermal head, etc. and transferring the melted thermal transfer layer or sublimated dye to the recording material. It is something to do.

When recording printed images of different densities, that is, gradation recording, using such a thermal transfer recording method, in the latter method of using heat sublimable dye among the above-mentioned methods,
By utilizing the difference in vapor pressure of the dye due to temperature, 1
It is possible to perform gradation recording. However, in this case, since the vapor pressure of the sublimable dye is at a level that cannot be ignored in the long term even at room temperature, there is a problem that the storage stability of the heat-sensitive transfer material and the transferred recorded image is low.

On the other hand, the former method that uses heat-melt ink (heat-melt transfer method) is superior in terms of heat-sensitive transfer material, preservation stability of heat-sensitive transfer recorded images, and sensitivity, but it is difficult to perform gradation recording. It was difficult.

The main object of the present invention is to eliminate the drawbacks of the above-mentioned thermal transfer recording method, and to provide a thermal transfer material that can change halftone recorded images with excellent uniformity and reproducibility while using a thermal melt transfer method. , and a thermal transfer recording method using the same. .

As a result of research for the above-mentioned purpose, the present inventor has found that a transfer recorded image of normal density (dark) is produced in response to a relatively small amount of energy application, while a transfer recorded image of normal density is produced in response to a relatively large amount of energy application. It has been found that it is extremely effective to form a heat-transferable ink layer that provides a so-called intermediate tone (E!J) transfer recorded image on a base material to prepare a heat-sensitive transfer material.

The thermal transfer material of the present invention is based on such knowledge, and more specifically, it includes a layer of a first thermal transfer ink on a base material, and a second layer having a melting point lower than that of the first thermal transfer ink.
pJJl thermal transferable ink layer is provided in this order in this order, and the pJJl thermal transferable ink layer has a lighter color tone than the second thermal transferable ink layer.

Further, the thermal transfer recording method of the present invention provides a layer of a first thermal transfer ink and a layer of a second thermal transfer ink having a lower melting point than the first thermal transfer ink on a substrate in this order. and the second thermal transferable ink layer of the thermal transfer material in which the first thermal transferable ink layer has a lighter tone than the second thermal transferable ink layer is opposed to the recording material, and the following (a) or (b) It consists of the step of applying a pattern of heat or voltage corresponding to either one of the amounts of energy to the thermal transfer material from the base material side, and transferring the thermal transfer ink that has been melted or softened according to the pattern to the recording material. It is characterized by this.

(a) Amount of energy for melting or softening only the second thermal transfer ink in the pattern.

(b) The amount of energy for melting or softening both the first and second thermal transfer inks in the pattern.

In the thermal transfer material of the present invention, the formation of a half-tone recorded image is achieved by transferring almost the entire amount of the first and second thermal transfer inks corresponding to the desired print pattern to the recording material, This is not achieved by transferring only either the first or second thermal transfer ink, ie, for forming a half-tone recorded image.

It is not necessary to selectively melt or soften either of the two inks.

Therefore, if the thermal transfer material of the present invention is used, it is extremely easy to control the amount of energy applied to form the above-mentioned halftone recorded image, and the print density of the halftone recorded image can be reduced by a minute change in the applied energy. Since it does not change, it is possible to stably provide a halftone recorded image with excellent uniformity and reproducibility.

The applied energy star and print density ( FIG. 1 shows an example of the relationship between the reflection density and the reflection density. Looking at FIG. It is easy to understand that

On the other hand, when a conventional heat-melting transfer type thermal transfer material is used in the same manner as above, the relationship between the amount of applied energy and the print density is conceptually shown in Figure 2. The range of the semi-finished Nerki that provides a print density of 1 is extremely narrow, and within this range, the print density changes greatly due to a minute change in applied energy.

Hereinafter, the present invention will be explained in more detail with reference to the drawings as necessary. “%” indicates quantitative ratio in the following descriptions.
and "parts" are based on the quantity unless otherwise specified.

FIG. 3 is a schematic cross-sectional view in the thickness direction showing the most basic shape of the thermal transfer material of the present invention.

Referring to FIG. 3, a thermal transfer material 1 is formed by forming a thermal transfer layer 3 on a base material 2, usually in the form of a sheet (used to include a film).

As the base material 2, conventionally known films and papers can be used as they are; for example, relatively heat-resistant plastic snack films such as polyester, polycarbonate, triacetyl cellulose, polyamide, polyimide, cellophane or sulfuric acid can be used as the base material 2. Paper, condenser paper, etc. can be suitably used. The thickness of the base material 2 is 1-15 uL when considering a thermal head as a heat source during thermal transfer.
It is desirable that the temperature be about m, but there is no particular restriction if a heat source such as a laser beam that can selectively heat the thermal transfer layer 3 is used. Further, a heat-resistant protective layer made of silicone resin, fluororesin, etc. may be provided on the surface of the base material that comes into contact with the thermal head.

According to the invention, the thermal transfer layer 3 on the substrate 2 is composed of a layer 3a of a first thermal transferable ink having a light tone and a layer 3b of a second thermal transferable ink having a dark tone.

The first thermal transfer ink and the second thermal transfer ink are
Both are made by dispersing a colorant in a heat-melting binder (this does not mean that the colorant is dissolved). As the heat-melting binder, the binder conventionally used in heat transfer inks is used as is. However, the melting point of the heat-melting binder constituting the first heat-transferable ink is preferably 60 to 180°C, and the melting point of the heat-melting binder constituting the second heat-transferable ink is preferably 50 to 120°C.
0°C is preferred.

In addition, in this specification, JIS K
The softening point according to the ring and ball method specified in 2406 is used instead of the above melting point.

Examples of such heat-melting binders include polyamide resins, polyester resins, epoxy resins, polyurethane resins, polyacrylic resins, polyvinyl chloride resins, cellulose resins, polyvinyl alcohol resins, and oil-based resins. Thermoplastic resins such as resins, phenolic resins, and polystyrene resins such as styrene-acrylic symbiotic combinations; Elastomers such as natural rubber, styrene-butadiene rubber, imprene rubber, and chloroprene rubber;
Natural waxes such as spermaceti wax, beeswax, lanolin, carnauba wax, candelilla wax, montan wax, and ceresin wax; Petroleum waxes such as paraffin wax and microcrystalline wax; Oxidized waxes, ester waxes, low molecular weight polyethylene, Fischer-Tropsch wax, etc. Synthetic wax: 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; Esters such as fatty acid esters of sucrose and fatty acid ester of sorbitan; Amides; etc. are used.

The above-mentioned heat-melting binders may be used in combination of two or more types depending on the trade requirements, and additives such as plasticizers, oil agents, or surfactants may be added to this binder. Its melt viscosity, adhesive strength, or wood affinity
It is also possible to adjust the degree of hydrophobicity and the like.

If a surfactant having a property of increasing the affinity of the entire ink for either the first or second thermal transfer ink is used, the difference between the first ink layer 3a and the second ink layer 3b can be improved. This is preferred in terms of functional separation and in that it facilitates the formation of the second ink layer 3b on the first ink layer 3a.

The coloring agents constituting the second thermal transfer ink together with the heat-melting binder include carbon black, nigrosine dye, lamp black, Sudan black SM, alkali blue, First Niro Q, benzidine yellow, pigment yellow, and India first.・Orange, Irgazine Red, Varanitroaniline Red, Toluidine Left, Carmine FB, Perpetual Bordeaux F
RR, Pigmentona Orange R, Resole Red 20
．． Lake φ Red C, Rhodamine FB, Rhodamine B Lake, Methyl-Violet B Lake, Phthalocyanine Blue, Pigment Blue, Prilliant Green B
, Phthalocyanine Green, Oil Yellow 〇G, Zapon First Niro 10 GG, Kayaset Y963, Kayaset YG, Sumiplast Yellow GG, Zapon First Orange RR, Oil Scarlet, Sumiplast Orange G, Orazole Brown B, Pomelo First Scarlet CG, Eizenspiron Red,
BEH, Oil Pink OP, Victoria Blue F4R,
All known dyes and pigments commonly used in the printing and recording fields can be used, such as Fastgen Blue 5007, Sudan Blue, and Oil Peacock Blue.

Such dyes and pigments may be used in combination of two or more types as necessary, but in amounts of 1 to 40% for the second thermal transfer ink.
It is preferable that the content is %.

On the other hand, as the coloring agent constituting the first thermal transfer ink together with the above-mentioned heat-melting binder, it is also possible to use the above-mentioned dyes and pigments.

From the viewpoint of efficiently hiding the color tone of the second thermal transfer ink, it is preferable that the 18th transfer ink contains a masking color agent.

This opaque colorant is an ink prepared by dispersing 30 parts of the colorant in 100 parts of a heat-melting binder.

A layer with a thickness of 15 to 20 gm allows a black printed image (optical reflection density = about 1.2) on the recording material to be formed with an optical reflection density of 0.
It is preferable to have a hiding power that can be reduced to 2 or less.

Examples of such opaque coloring agents include inorganic pigments such as titanium dioxide, zinc white, silicon dioxide, white lead, basic lead sulfate, lead sulfate, lithopone, zinc sulfide, and antimony oxide; inorganic pigments such as potassium titanate. Fiber: Organic pigments such as aluminum salts and magnesium salts of organic compounds, aluminum metal powder, etc. are used, but the above-mentioned colorants with high hiding power are preferably used. Among these colorants, titanium dioxide, which has excellent properties such as hiding power and whiteness, is particularly preferably used. Two or more of these concealing coloring agents may be used in combination, if necessary.

Further, the opaque coloring agent may be used in combination with the dyes and pigments mentioned above.

These colorants are preferably used in an amount of 5 to 60% based on the first thermal transfer ink;
The thermal transfer ink layer 3a is the second thermal transfer ink layer 3.
In other words, the first thermally transferable ink layer 3a is used to exhibit a lower optical reflection density than the second thermally transferable ink layer 3b.

The first and second thermal transfer inks are composed of the above-mentioned hot-melt binder and colorant (and additives added as necessary), but the melting point of the first thermal transfer ink, which has a high melting point, is The temperature is preferably 60-180°C, and the melting point of the second thermal transfer ink having a low melting point is preferably 50-120°C.
If the melting point of the first thermal transfer ink exceeds 180°C, a large amount of energy will be required to melt or soften the pattern of the ink, and if the melting point of the second thermal transfer ink exceeds 180°C, a large amount of energy will be required to melt or soften the ink pattern.
If the temperature is lower than 0°C, the storage stability of the thermal transfer material 1 will deteriorate and stains (background stains) will occur in the non-printed areas of the recording material.

Further, the difference in melting point between the first thermal transfer ink having a high melting point and the second thermal transfer ink having a low melting point is 10°C or more, and more preferably 20°C to 7°C.
If the difference in melting point, which is preferably 0° C., is less than 10° C., it will be difficult to separate the functions of the first thermal transfer ink layer 3a and the second thermal transfer ink layer 3b.

In order to further improve the functional separation of the first ink layer 3a and the second ink layer 3b, the difference in melt viscosity of the thermal transfer ink can be used to mix the first and second ink layers when they are melted or softened. It is preferable to suppress.

In this case, for example, a heat-melting binder mainly composed of resin or the like is used for the first thermal transfer ink, and the 140%
The melt viscosity at °C is preferably 1037 inch poise (
cP) or above (including the case where it is not substantially melted at 140"O), and on the other hand, if the second thermal transfer ink is a heat-melting binder mainly composed of wax, the melting temperature at 140" Preferably the viscosity is 10-10
By setting ``cP'', the melt viscosity of the first thermal transfer ink may be Uf, preferably 102 times or more, the melt viscosity of the second thermal transfer ink.

It is preferable that the first thermal transfer ink layer 3a and the second thermal transfer ink layer 3b are formed to have a thickness of 1 to 1 loom, respectively, but the efficiency of patterned heat supply to the second ink layer 3b is In order to improve the performance, it is preferable that the first thermal transfer ink layer be thinner.

The total thickness of the thermal transfer layer 3 consisting of the first ink layer 3a and the second ink layer 3b is preferably 3 to 30 m.

In order to obtain the thermal transfer material 1 of the present invention, for example, in the heat-melting binder constituting the first thermal transfer ink described above,
Add a colorant (additives if necessary) and melt and knead using a dispersion device such as an attritor, or knead with an appropriate solvent, and apply to the base material 2 by a general coating method or printing method. First, apply the first ink layer 3 on top.
Then, on this first ink layer 3a-a,
A solution obtained by dispersing the heat-melting binder and colorant (additives as necessary) constituting the second thermal transfer ink in a solvent (for example, a hydrophilic solvent) that is incompatible with the first thermal transfer ink. The second ink layer 3b may be formed by applying the dispersion liquid in the same manner.

It is also possible to form the second ink layer 3b by applying the second thermal transfer ink onto the ink layer 3a while melting the second thermal transfer ink at a temperature lower than the melting point of the first thermal transfer ink.

Next, regarding the thermal transfer recording method of the present invention using the above-mentioned thermal transfer material 1, FIGS.
This will be explained with reference to Figure (a).

Referring to FIG. 4(a), the recording material 4 is made to face the thermal transfer layer 3 of the thermal transfer material 1, and the thermal pad 5 is made to face the base material 2 side of the thermal transfer material 1. At this time, as shown in FIG. 4(b), a voltage Vl corresponding to the amount of thermal energy for melting or softening only the second thermal transferable ink layer 3b in a pattern according to the image signal is applied to the thermal heater 5. In other words, as shown in FIG. 4(a), only the second thermal transfer ink having a dark tone is transferred to the recording material 4, and as shown in FIG. On the recording material 4, a transfer recorded image 33b of a normal printing density (dark) made of the second thermal transfer ink is formed.

On the other hand, referring to FIG. 5(a), as in the case of FIG. ), the P of the first thermal transfer ink:! When I3a and the second thermal transfer ink layer 3b both melt or soften in a pattern, a voltage v2 corresponding to the thermal energy is applied to the thermal heater 5, resulting in a pale color tone as shown in FIG. 5(a). The first thermal transfer ink having a dark tone and the second thermal transfer ink having a dark tone are both transferred to the recording material 4, and as shown in a schematic plan view in FIG. A half-tone (thin) transfer recorded image 33a made of the il and the second transferable ink is formed.

The applied energy as described above and the first and :fS2
An example of the relationship between the amount of thermal transfer ink transferred to the recording material 4 is shown in FIG. 6. In FIG. The amount of ink transfer on the vertical axis is expressed relative to the amount of saturated transfer of each of the first or second thermal transfer ink. Indicated by value.

As shown in FIG. 6, as a result of the mechanical separation in response to the applied energy of the first and second thermal transfer inks, the print density (optical reflection density) of the transferred recorded image given by the thermal transfer material 1 and the applied energy The relationship with the amount is as shown in FIG. 1 mentioned above, and it becomes possible to obtain a stable halftone recorded image. In FIG. 1, the amount of applied energy on the horizontal axis is expressed as a relative value with the saturated transfer energy amount being 1.

In the above-described thermal transfer recording method, by controlling the voltage applied to the thermal head 5, the thermal transfer material 1 is
The amount of energy applied to the pattern is changed, but instead of controlling this voltage, the
By controlling the communication time etc. given to
It is easy to understand that the same effect can be obtained even if the amount of applied energy is changed.

Separately, a needle-like or multi-stylus-like recording electrode is used in place of the thermal head 5, and the specific resistance is 10-1.
The desired heat is supplied to the thermal transfer layer 3 by applying a patterned voltage to the base material 2 (or in addition to this, the thermal transfer layer 3) which has a conductivity of about 0'Ω·cm to generate Joule heat. It is also possible.

In the above, an embodiment of the present invention using a thermal transfer material 1 as shown in FIG. 3 has been described, and FIG. 7 is a schematic cross-sectional view in the thickness direction thereof.

First thermal transfer ink layer 3a and second thermal transfer ink layer 3b
between the first and second thermal transfer inks, and preferably has a thickness of 0.5-5.
A 4 m intermediate layer 3c may be provided.

When such an intermediate layer 3c is provided, the first ink layer 3a
This is preferable because mixing with the second ink layer 3b during heat application is further suppressed.

l Mitate 1j As described above, according to the present invention, a high melting point first
A thermal transfer material is provided in which a layer having a light tone made of a thermal transfer ink and a layer having a dark tone made of a second thermal transfer ink having a low melting point are provided in this order.

The thermal transfer material of the present invention provides a transferred recorded image of normal density in response to the application of a relatively small amount of energy, and provides a transferred recorded image in half tone in response to the application of a relatively large amount of energy. By using the thermal transfer material of the present invention, halftone recorded images with excellent uniformity and reproducibility can be stably formed.

The present invention will be explained in more detail below with reference to Examples.

111 cases Length j self 1” Ink coating liquid A Ink coating liquid A was obtained.

Next, each component was uniformly dispersed using a 7 triter according to the composition shown in Table 1 below to obtain an ink coating liquid BD.

Table 1 (!r! parts) (1 mark is calculated as solid content) After applying ink coating liquid A using an applicator onto a 6 gm thick polyethylene terephthalate film as a base material, dry it to determine the dry thickness. 5 tiles, a primary layer on which a white first thermal transfer ink layer was formed.

Ink coating liquid B was applied onto the first thermal transferable ink layer using an applicator, and then dried to a dry thickness of 2ILm,
A layer of a black second thermal transfer ink was formed to obtain a thermal transfer material (2).

A thermal transfer material II was obtained in the same manner as in Example 1, except that ink coating liquid C was used instead of ink coating liquid B in Example 1 to form a second thermal transfer ink layer. Ta.

151'' A thermal transfer material (1) was prepared in the same manner as in Example 1 except that the second thermal transfer ink layer was formed using an ink coating liquid instead of the ink coating liquid B in Example 1. Obtained.

Red dispersion-dyed Ne13 was used instead of carbon black in Example 1.
A thermal transfer material (2) having a red second thermal transfer ink layer was obtained by processing in the same manner as in Example 1, except that Celestelent 3R, Bayer® TJJ) was used.

The four types of thermal transfer materials obtained in this way were attached to a printer CW-4251 used in a commercially available word processor (Cano Word 45S, manufactured by Canon Inc.), and the amount of energy applied to the thermal head (8 dots/mm) was A recorded image was formed on a high-quality paper serving as a recording material by changing the recording material, and the print density (Macbeth reflection density, optical reflection density according to:1) of the obtained recorded image was measured. The J11 results are shown in the second section below.
Table 12: Applied energy is 0.3 mJ/dot, and
Recorded images were formed in the same manner as above by varying the amount of applied energy, but the thermal transfer materials (I to ■) of the present invention
Normal density (print density 1.0 to 1.2) corresponding to applied energy in the range of 25 to 50% of the saturated transfer energy amount
In addition to giving a recorded image of
Corresponding to the applied energy in the range of 0 to 100%, a recorded image of halftone density (print density of 0.8 to 0.8) was stably provided with good uniformity and reproducibility.

[Brief explanation of drawings]

Figures 1 and 2 are graphs showing the relationship between the amount of applied energy and print density on a thermal transfer material, and Figure 6 is a graph showing the relationship between the amount of applied energy and the amount of ink transfer. FIG. 6 shows the above relationship in the thermal transfer material of the present invention, and FIG. 2 shows the above relationship in the conventional heat-melting transfer type thermal transfer material. FIG. 3 shows a typical embodiment of the thermal transfer material of the present invention;
The figure is a schematic cross-sectional view in the thickness direction showing another embodiment, FIG.
a) or C) and Figure 5 (a) or c) are 1
4(a) and 5(a) are schematic cross-sectional views in the thickness direction of a thermal transfer material; FIG. Figure 4 (C) and Figure 5 (e) are schematic plan views, Figure 4 (
b) and FIG. 5(b) are graphs showing the pulses applied to the thermal head. l...Thermal transfer material. 2...Base material. 3... Thermal transfer layer, 3a... First thermal transferable ink layer, 3b... Second thermal transferable ink layer, 3c... Intermediate layer, 4... Recording material, 5... Thermal head . ■'': Fig. 3 Applicant's agent 'gQW α Male 7, -11-z Book 1 Fig. f-r) D Roenel 100°°- 112 Fig. →Rashisen-1 Figure 7

Claims (1)

[Claims] 1. A layer of a first thermal transfer ink and a layer of a second thermal transfer ink having a lower melting point than the first thermal transfer ink are provided in this order on a base material, and A heat-sensitive transfer material, wherein the first heat-transferable ink layer has a lighter tone than the second heat-transferable ink layer. 2. The thermal transfer material according to claim 1, wherein the first thermal transfer ink contains an opaque colorant. 3. A layer of a first thermally transferable ink and a layer of a second thermally transferable ink having a lower melting point than the first thermally transferable ink are provided on the base material in this order, and the first thermally transferable ink layer a step of opposing a second thermal transferable ink layer of a thermal transfer material having a lighter color tone than the second thermal transferable ink layer to a recording material, and corresponding to the energy amount of either (a) or (b) below. A thermal transfer recording method comprising the steps of applying patterned heat or voltage to a thermal transfer material from the base material side and transferring melted or softened thermal transfer ink to a recording material according to the pattern. . (a) the amount of energy that melts or softens only the second thermal transfer ink in the pattern; (b) the amount of energy that melts or softens both the first and second thermal transfer inks in the pattern. 4. The thermal transfer recording method according to claim 3, wherein the first thermal transfer ink is an ink containing an opaque colorant.