JPH0247091A - Thermal sensitive transfer material - Google Patents

Abstract

PURPOSE:To print a beautiful color-tone without omission of fringe, middle when both a first ink layer and a second ink layer are transferred by equally setting the transfer starting temperature of the first layer to that of the second layer to a recording medium. CONSTITUTION:It is desirable to set the adhering strength F1 of a support 2 to a first ink layer 4 to 0.1-10g/cm in case of precise recording when the force F1 is reduced by thermal printing. Since it is slightly difficult to realize the desirable adhering strength range when the transfer starting temperature (m1) of the first ink layer is varied, it is easy to regulate the transfer starting temperature (m2) of a second ink layer 5 to m1=m2. A binder composition except colorant for composing the second layer contains at least waxes as impregnating accelerator for a recording sheet, resins as impregnating suppressor in such a manner that the ratio of the waxes to the resins is desirably 95/5-30/70.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a two-color thermal transfer material for transferring two-color recorded images onto a recording medium made of plain paper or the like.

The thermal transfer recording method has the general characteristics of the thermal recording method that the equipment used is lightweight, compact, noiseless, and has excellent operability and maintainability. Furthermore, it has the feature of excellent durability of recorded images, and has been widely used recently.

This heat-sensitive transfer recording method generally uses a heat-sensitive transfer material formed by coating a sheet-like support with a heat-transferable ink made of a heat-melting binder and a colorant dispersed therein. The molten ink layer is superimposed on the recording medium so as to be in contact with the recording medium, and heat is supplied from the support side of the thermal transfer material by a thermal head to transfer the melted ink layer onto the recording medium. A transfer recording image is formed on the body according to the shape of heat supply.

Furthermore, there is a strong market demand for two-color printing while taking advantage of the advantages of the thermal transfer recording method, and various techniques for obtaining two-color printing have been proposed.

Conventionally, as a method for printing in two colors on plain paper using a thermal transfer recording method, Japanese Patent Application Laid-Open No. 148591/1983 discloses two heat-melting high-melting point printing methods in which different colorants are contained on a base material. Ink layer A and low melting point ink layer B are sequentially laminated from the base material side, and in the case of low heat applied energy, only the low melting point ink layer B is transferred onto the plain paper, and in the case of high heat applied energy, the heat melting ink layer is transferred onto the plain paper. A two-color thermal transfer recording element is disclosed that provides a two-color recorded image by transferring both A and B.

Further, JP-A No. 59-84389 discloses a two-color thermal transfer in which an ink layer is provided on a base material, which is composed of an ink that melts and leaches when heated, and an ink that melts and peels off at a temperature higher than the melting and leaching temperature. An ink sheet is disclosed.

In these methods, two-color printing is performed by changing the temperature of the ink layer by changing the energy applied to the thermal head in two stages. However, if high energy is applied to raise the temperature of the ink layer,
Due to the diffusion of heat, a relatively low-temperature area is created around the high-temperature area, and as a result, a border of the color printed at a low temperature appears around the area printed at a high temperature. Additionally, applying high energy to a thermal head will cause its temperature to drop.
Because it takes a relatively long time to print, colors printed at low temperatures tend to trail behind areas printed at high temperatures.

In addition, in both methods, there is a restriction that a material with a relatively low melting point must be used as an ink material for printing at a low temperature, resulting in problems such as background smearing and a decrease in storage stability.

As a technique for solving this drawback, the present applicant previously proposed a recording method in Japanese Patent Application No. 60-298831.

In this recording method, at least first and second
By using a heat-sensitive transfer material provided with an ink layer and applying heat to the heat-sensitive transfer material, the second ink layer can be selectively or , a method in which both the first and second ink layers are transferred to a recording medium.

This recording method made it possible to solve various problems such as "edging" and "tailing" of printing mentioned above, but even with this new two-color recording method, it is possible to improve printing even further. Improvement in quality is desired.

The present inventors proposed a heat-sensitive transfer material suitable for recording with even higher definition (Japanese Patent Application No. 62-48586). However, even if such a thermal transfer material is used, it is not necessarily easy to perform high-definition two-color recording on recording paper with low smoothness. That is, in this case, when both the first and second ink layers are transferred, the color tone of the first ink cannot cover the color tone of the second ink, resulting in so-called "edging" at the edges of the recorded image and the center of the recorded image. In some cases, a problem occurs in which the second ink is exposed due to the "r hollow part" occurring in the second ink.

There is a strong desire for a thermal transfer material that can print with clear color tones at the edges and center of the print, even when such a high-definition thermal head is used and recording paper with a low surface smoothness is used. However, it has not always been easy to achieve such an improvement in printing quality because it is related to actual recording conditions such as heat application conditions or peeling conditions.

The main object of the present invention is to solve the above-mentioned drawbacks of the conventional two-color printing method, to provide beautiful printing with different tones on plain paper in a simple manner, and to print with high-definition thermal printing. It is an object of the present invention to provide a thermal transfer material that can provide clear printing even when an application means is used.

[Cram] Nori 1! As a result of intensive research, the present inventors have discovered how to prevent "edges" and "hollow holes" in recorded images on low-smooth recording materials in recording methods using high-definition heat application means as described above. In order to achieve this, it is necessary that the transfer start temperature (m2) of the second ink layer under certain conditions is substantially equal to the transfer start temperature (m1) of the first ink layer under other specific conditions. I found it.

The thermal transfer material of the present invention is based on the above-mentioned knowledge, and more specifically, at least an adhesive layer, a first ink layer, and a second ink layer are sequentially provided on a support from the support side. , and the transfer start temperature (m1) of the first ink layer to the recording medium is substantially equal to the transfer start temperature (m2) of the second ink layer to the recording medium. .

Hereinafter, the present invention will be described in further detail with reference to the drawings as necessary. In the following descriptions, "%" is used to express quantitative ratio.
” and “parts” are based on weight unless otherwise specified.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 is a schematic cross-sectional view in the thickness direction showing a basic aspect of the heat-sensitive transfer material of the present invention. Referring to FIG. 1, a thermal transfer material 1 of the present invention includes a first adhesive layer 3, a first ink layer 4, and a second ink layer 5 provided on a support 2 in this order.

In the thermal transfer material of the present invention, the first ink layer 4 - the second ink layer
It is necessary that the magnitude relationship between the adhesive force F2 between the ink layers 5 and the adhesive force F1 between the first ink layer 4 and the support 2 be opposite at high temperatures and at low temperatures. When heat is applied to the thermal transfer material of the present invention, immediately after heating, the first ink layer 4 and the second ink layer
When the separation from the ink layer 5 is better than the separation between the first ink layer 4 and the support 2, and when the time from heating to separating the support 2 from the recording medium is long, that is, when the thermal transfer material 1 and the substrate are When the recording medium is brought into close contact with the recording medium facing each other, heat is applied, and the thermal head runs while the recording medium is in close contact with the recording medium to cool the thermal transfer material.
The first ink layer 4 is configured to be easily peeled off from the support 2.

The above characteristics between each layer will be explained using FIG. 3. In the present invention, the adhesive force F2 between the second ink layer and the first ink layer and the adhesive force Fl between the first ink layer and the support are substantially determined when transfer recording is performed on the recording medium. Basically, when the second ink layer is transferred, the adhesive force of the latter is greater, and when both ink layers are substantially transferred, the adhesive force of the former is greater. When the layer is peeled off from the thermal transfer material and transferred to the recording medium, the form of peeling of the ink layer (for example, whether the position of peeling is at the exact boundary between the second ink layer and the first ink layer, etc.) shall not be considered.

The adhesive force F2 between the first ink layer 4 and the second ink layer 5 and the adhesive force F between the first ink layer 4 and the support 2 change with heating or cooling.

In a preferred embodiment of the present invention, in order to control the adhesive force F between the first ink layer 4 and the support 2, the first ink layer 4
An adhesive layer 3 is provided between the substrate 2 and the support 2, and the adhesive layer 3 causes the adhesive force to irreversibly decrease before and after applying heat.

The adhesive force F2 between the first ink layer 4 and the second ink layer 5 and the adhesive force F between the first ink layer 4 and the support 2 must be strong to a certain extent or more before heat is applied. If this initial adhesive strength is low, problems such as storage stability and ink removal as a thermal transfer material arise.

In the thermal transfer material of the present invention, when heat is applied by the thermal head and the temperature rises, the adhesive force F2 between the first ink FJ4 and the second ink layer 5 increases. The force decreases rapidly compared to the force F. Therefore, in the state immediately after heat is applied and before the temperature drops, the first
The adhesive force F2 between the ink layer 4 and the second ink layer 5 becomes weaker than the adhesive force F1 between the first ink layer 4 and the support 2. Therefore, if the recording medium and the thermal transfer material are separated immediately after the second ink layer 5 adheres to the recording medium by heat application, that is, at time t in FIG. 3, only the second ink layer 5 will be transferred. .

Also, as time passes after heating and the ink layer temperature decreases,
The adhesive force F between the first ink layer 4 and the second ink layer 5 is restored to the same level as before the heat application. However, in this embodiment,
Since the adhesive force F1 between the first ink layer 4 and the support 2 is configured to irreversibly decrease before and after heat application due to the adhesive layer 3, it does not return to the state before heat application. Therefore, the adhesive force F,
is smaller than the adhesive force F2. At this time, that is, time t2
If separated at , the first ink layer 4 is also transferred together with the second ink layer 5. If the color tones of the first ink layer 4 and the second ink layer 5 are changed here, two-color recording can be obtained.

If you want to obtain the same color tone as the first ink layer 4 and the second ink layer 5, the first ink layer 4 should have a darker color such as black, and the second ink layer 5 should have a lighter color than the first ink layer, such as red. It is better to place things of color. Further, by setting the first ink layer and the second ink layer to similar colors, it is possible to record in two colors, dark and light. Furthermore, by making the first ink layer a layer containing a white pigment or the like having a large concealing effect, the first ink layer can also function as a correction ink layer.

After applying heat, the adhesive force F between the first ink layer 4 and the second ink layer 5
2 recovers to its initial state over time, but the separation time t2
, the adhesive force F1 between the first ink layer 4 and the support 2 is the first
After receiving heat, the adhesive force F becomes clearly smaller than the adhesive force F2 between the ink layer 4 and the second ink layer 5.
When a predetermined period of time has elapsed (that is, when both the first and second ink layers are transferred), 1. og/cm~10g/cm
It is desirable for high-definition recording.

The value of F after applying heat to the thermal transfer material is measured as follows.

Polyethylene terephthalate (hereinafter referred to as rPETJ)
Adhesive layer 3, first ink layer 4 and second ink layer 5 are formed on the film support at 0°5.2,0 and 2.0°, respectively.
3/m2, the surface of the ink layer and the recording medium (thermal transfer paper TC-80, manufactured by Honshu Paper Co., Ltd.) are overlapped, and PET
The energy in the heat head is 13 mJ/dot.
, apply heat with a pressing force of 600 g/cm. Next, P
Tensile strength tester (Tensilon RTM-100 model manufactured by Toyo Baldwin Co., Ltd.) without separating the ET and the recording medium.
At room temperature (25°C), the peeling angle was 180 degrees and the peeling speed was 300 mm/min.
The force when the first ink layer is almost transferred to the recording medium 1 is measured by peeling off the T and the recording medium, and this is converted into a force per 1 cm of width.

As described above, in the thermal transfer material of the present invention, the transfer start temperature (ml) of the first ink layer 4 to the recording medium and the transfer start temperature (ml) of the second ink layer 5 to the recording medium are substantially equal to each other. are constructed so that they are equal. Here, "substantially equal" means that the absolute value of (m2m+) is 15° C. or less. In the present invention, 1m2m of
+l is preferably 10°C or less, more preferably 5°C or less.

When the transfer start temperature (ml) of the second ink was substantially lower than the transfer start temperature (ml) of the first ink layer, both the first and second ink layers were transferred to the low smoothness recording paper. In this case, portions where only the second ink layer is transferred occur at the center and edges of the recorded image. This is because at the center of the recorded image, the second ink penetrates into the recording paper with low smoothness too much, and the first ink layer, which has low adhesive strength to the recording paper, comes into contact with the recording paper, causing transfer failure. It is estimated that this is due to

On the other hand, at the edges of the recorded image, since the recording paper has low smoothness, there are fewer contact points between the second ink layer and the recording paper, that is, the adhesive force (F3) of the ink layer to the recording paper is small, and It is presumed that because Fl in that portion is not sufficiently lower than F, the transfer of the first ink layer is poor. That is, after heat application (e.g. Fl
(due to a decrease in ” occurs.

Here, the transfer start temperature (ml) of the first ink layer is a temperature defined as follows.

That is, the heat-sensitive transfer material 1 was placed on a hot bench (temperature gradient plate) manufactured by Reichert so that the support 2 side was in contact with the heat-sensitive transfer material 1, and plain paper (Beck smoothness: 20 seconds) was placed on the ink surface of the heat-sensitive transfer material. After superimposing them and applying a load of 3 Kg/cm for 1 second on the plain paper, the heat-sensitive transfer material and the plain paper are returned to room temperature while being superimposed. Next, apply the thermal transfer material at 180 degrees to the plain paper from the high temperature side where the heat history has been.
Peel it off at an angle of

In this case, the lowest temperature at which both the first and second ink layers begin to be transferred onto the plain paper (temperature on the thermally inclined plate) is defined as the transfer start temperature (ml) of the first ink layer. That is, m is the adhesive force between the second ink layer and the recording medium (
F3) and F1 are the lowest temperatures at which Fl = F3. In a preferred embodiment of the present invention in which the adhesive force F irreversibly decreases before and after heat application, m is the adhesive force F,
is substantially equal to the temperature at which it begins to decline.

On the other hand, the transfer start temperature (ml) of the second ink refers to a temperature defined as follows. That is, similarly to the measurement of ml described above, plain paper and thermal transfer material are superimposed on a hot bench with a load of 3 kg/am, and the plain paper is peeled from the thermal transfer material at an angle of 90'' on the hot bench. .

In this case, the lowest temperature (temperature on the thermal gradient plate) at which only the second ink starts to be transferred onto the plain paper is defined as the transfer start temperature (m2) of the second ink.

The temperature gradient on the thermally inclined plate in the measurement of ml m2 is usually about 10°C/cm, more preferably about 5°C/cm.

In addition, the relationship of ml m2 defined in this way is m2>
ml is not preferable because the energy consumed for thermal transfer recording becomes large.

The thermal transfer material of the present invention is constructed so that the relationship between ml and m2 obtained by the above measurement method substantially satisfies m1=m2. When producing the thermal transfer material of the present invention, in high-definition recording, when the adhesive force (Fl) between the support and the first ink layer decreases due to heat application, it becomes zero.
．． It is preferable that it becomes 1-10 g/cm. When changing the transfer start temperature (or the temperature at which the adhesive force F starts to decrease) ml of the first ink layer, it is somewhat difficult to achieve this preferable adhesive force range due to the formulation, so the thermal transfer material of the present invention In order to obtain this, it is easier to adjust the transfer start temperature (m2) of the second ink layer so that m, = m2.

It is preferable that the binder composition excluding the colorant for forming such a second ink layer contains at least waxes as a penetration enhancer into the recording paper and resins as a penetration inhibitor.

Although this is not particularly limited, the ratio of waxes to resins is preferably 9515 to 30/70, more preferably 90/10 to 50150.

The wax component has a softening temperature of 60°C to 150°C.
It is preferred to use a wax at .

As these wax components, the following can be used as conventionally known wax components. Whale wax, Miroku,
lanolin, carnauba wax, candelilla wax,
Natural waxes such as montan wax and ceresin wax; Petroleum waxes such as paraffin wax and microcrystalline wax; Synthetic waxes such as ester wax, low molecular weight polyethylene, and Fischer-Tropsch wax; Lauric acid, myristic acid, valmitic acid, stearic acid, behenic acid Higher fatty acids such as: higher alcohols such as stearyl alcohol and behenyl alcohol; esters such as sucrose fatty acid ester and sorbitan fatty acid ester; amides such as nioleylamide can be used alone or in appropriate mixtures.

Particularly preferred waxes have a softening temperature of 80°C to 150°C.
, a polyethylene wax with a number average molecular weight of 1000 to 6000, more preferably a softening temperature of 90°C to 14°C.
It is a polyethylene wax having a temperature of 0°C and a number average molecular weight of 2,000 to 5,000. Furthermore, the softening temperature is 90°C to 140°C.
℃ and number average molecular weight of 2000 to 5000 is particularly preferred.

In addition, the softening temperature referred to in the present invention refers to the softening temperature of Shimadzu Flow Tester CF.
This is the outflow starting temperature when the apparent viscosity-temperature curve of the sample ink is determined using a T-500 model under the conditions of a load of 10 kg and a temperature increase rate of 2° C./min.

In the present invention, the number average molecular weight of polyethylene wax (used to include oxidized polyethylene wax) is determined by the following measuring method.

(Molecular weight measurement method) vpo method (Vapor Pressure Osmom
For example, using benzene as a solvent, polyethylene wax is heated at 2 to 1.0
Dissolve in g/l 00ml benzene at several different concentrations (C), measure each osmotic pressure (π/C), and plot the concentration C - osmotic pressure π/C. Osmotic pressure at infinite dilution (π/C
). Read from this plot, (π/C). = R
The number average molecule iMn is determined from the formula of T/Mn.

On the other hand, resins include vinyl resins such as polyamide resins, polyester resins, extremely high molecular weight epoxy resins, polyurethane resins, polyacrylic resins (e.g. polymethyl methacrylate, polyacrylamide), polyvinylpyrrolidone, etc. resin, polyvinyl chloride resin (e.g. vinyl chloride-vinylidene chloride copolymer,
(vinyl chloride-vinyl acetate copolymer, etc.), cellulose resin (e.g. methyl cellulose, ethyl cellulose, carboxymethyl cellulose, etc.), polyvinyl alcohol resin (e.g. polyvinyl alcohol, partially saponified polyvinyl alcohol, etc.), stone RTT+ resin, rosin conductor , coumaron-indene resin, terpene resin, novolak type phenolic resin, polystyrene tea resin (e.g. styrene-acrylic copolymer, etc.), polyolefin resin (e.g. polyethylene, polypropylene, polybutene,
(ethylene vinyl acetate copolymer, etc.), polyvinyl ether resin, polyethylene glycol resin and elastomers, natural rubber, styrene-butadiene rubber, isoprene rubber, styrene-butadiene latex, nitrile
Latices such as butadiene latex, acrylic latex, vinyl acetate latex, ionomer resins, etc. can be used alone or in appropriate mixtures.

The resin preferably has a softening point of 300°C or lower, particularly 250°C or lower, and may be in a softened state at room temperature.

The colorant content of the second ink is preferably 3 to 80%, more preferably 5 to 50%, based on the second ink. If the colorant content is less than 3%, the coloring power will be low and a desirable density of the recorded image cannot be obtained, while if it exceeds 80%, it will be difficult to control the transfer start temperature m2 of the second ink layer.

The softening temperature of the second ink containing the colorant is 90 to 2
00°C, more preferably 95-150°C. Also, the second
Is the ink at a temperature 20°C higher than its softening temperature? 8
It is preferable to configure the composition so that the melt viscosity is 104 to 10'cps (according to the flow tester). This is to suppress penetration into recording paper with low smoothness and to prevent "hollow holes" in the center of the recorded image when both the first and second ink layers are transferred.

As the support 2, conventionally known films and papers can be used as they are, such as films of relatively heat-resistant plastics such as polyester, polycarbonate, triacetylcellulose, polyamide, polyimide, cellophane, or parchment paper. , condenser paper, etc. can be suitably used.

In addition, when a thermal head is used as a means for applying heat to the thermal transfer material, the surface of the support that comes into contact with the thermal head is
By providing a heat-resistant protective layer made of silicone resin, fluororesin, oliimide resin, epoxy resin, phenol resin, melamine resin, nitrocellulose, etc., the heat resistance of the support can be improved, or it is possible to improve the heat resistance of the support. It is also possible to use other support materials.

The thickness of the support 2 is preferably about 1 to 15 μm when considering a thermal head as a heat source during thermal transfer, but when using a heat source that can selectively heat the transfer layer, such as a laser beam, There are no particular restrictions.

It is preferable that the first adhesive layer 3 is configured so that the adhesive force F changes irreversibly before and after applying heat.
It is preferable that the adhesive layer 3 is composed of a wax component A and an adhesive component B. Further, it is more preferable to use the wax component A in the form of fine particles.

When fine-grained wax component A and adhesive component B are used, the state of the adhesive layer 2 before heat application is such that adhesive component B exists as a binder around fine-grained wax component A,
Furthermore, it is presumed that the support 2 and the first ink layer 4 are bonded together to prevent ink from falling off.

Once heat is applied in this state, the particulate wax component A within the adhesive N3 softens and forms a film as it is further cooled. As a result, the adhesive layer 3 is dominated by the wax film, and its flexibility is reduced, and its releasability becomes stronger than the adhesive force of the adhesive component. In the thermal transfer material of the present invention,
As mentioned above, this adhesive strength is 1.0 to 10.0 g/c
It is preferable that it decreases to m. Considering the decrease in adhesive strength after heat application, the mixing ratio of wax component A and adhesive component B in the adhesive layer is preferably 0.5≦A/B≦20,
More preferably 1≦A/B≦9, particularly preferably 1.
5≦A/B≦6.

As described above, the adhesive layer 3 is made of wax component A and adhesive component B.
As a result, the adhesive force between the support 2 and the first ink N4 decreases from the initial adhesive force before heat application to the adhesive force after heat application, and furthermore, an irreversible behavior that does not completely recover to the initial state occurs. It is possible to construct something that shows

In order to better exhibit the above effects, it is preferable to use a wax having a softening temperature of 60° C. to 150° C. as the wax component in the form of fine particles. As the wax component A, waxes used for the second ink layer can be used, and as the adhesive component, resins used for the second ink layer can be used. The softening point of the adhesive layer 3 is preferably 60 to 200°C.

The first ink layer 4 is preferably constructed by using a resin as a binder and adding a coloring agent to the binder. The resin used for the first ink layer 4 preferably has a glass transition point of 0°C or lower, more preferably -10°C or lower, and has a bowing elongation (based on the amount of elongation deformation) at 25°C (5 mm film thickness). The first ink layer 4, which has a relatively large (300% or more, preferably 500% or more) ratio to the length, is formed by adding a relatively large amount of coloring agent, especially pigment, to the binder, makes the layer as a whole It is preferable to suppress the tensile elongation and tensile strength.

The glass transition point of the binder used in the first ink layer 4 is 0.
By keeping the temperature below ℃, the first temperature is always maintained during printing and storage.
The binder of the ink layer is in a kind of supercooled liquid state and also has a relatively large tensile elongation, so it does not exhibit any brittleness. Therefore, when only the second ink layer 5 is transferred, a part of the first ink layer 4 is not transferred. If the tensile elongation of the binder r is less than 300%, it may exhibit brittleness.

The binder used for the first ink layer 4 is one that satisfies the above-mentioned conditions, such as acrylic acid alkyl ester copolymer, acrylonitrile/acrylic acid alkyl ester copolymer, styrene/acrylic acid alkyl ester copolymer, or methacrylic acid alkyl ester. - Acrylic acid ester copolymers such as acrylic acid alkyl ester copolymers, latex such as styrene-butadiene latex, nitrile-butadiene latex, acrylic latex, vinyl acetate latex; polyester urethane, polyether urethane, etc. These urethane resins and the like can be used alone or in an appropriate mixture. Further, binders such as wax and resin, and other additives may also be added as necessary.

The relatively low tensile strength and tensile elongation of the first ink layer 4 in the preferred embodiment is achieved by adding a relatively large amount of pigment to the binder.

The ratio of pigment in the first ink layer is preferably changed depending on the properties of the adhesive layer and the second ink layer to obtain an optimal ratio, but numerically it is 25 to 85% based on the first ink layer.
, more preferably 35 to 70%. If the pigment ratio is less than 25%, the tensile strength and tensile elongation of the binder will not decrease sufficiently, while if it exceeds 85%, the first ink layer will become brittle and color separation will not be sufficient when only the second ink layer is transferred. It disappears.

In the thermal transfer material of the present invention, as shown in FIG. 2, between the first ink layer 4 and the second ink layer 5, if necessary,
A second adhesive layer 6 may be provided to control the adhesive force between the two. In this case, since the adhesive force F2 between the first ink layer 4 and the second ink layer 5 is controlled by the second adhesive layer 6, the material selection and pigment content of the first ink layer 4 and the second ink layer 5 are controlled. You have more freedom to choose.

The softening temperature of the second adhesive layer 6 is desirably selected to be equal to or lower than the softening temperature of the second ink layer 5. When printing with a thermal head, the temperature of the thermal head changes between a printing state and a non-printing state at the end of the printing part in the direction of movement of the thermal head, but at that time, the strength of the second adhesive layer 6 remains relatively high and the second ink layer 5 adheres to the recording medium, there is a possibility that the first ink layer 4 is transferred together with the second ink layer 5. However, such a phenomenon can be prevented by selecting the softening temperature of the second adhesive layer 6 to be equal to or lower than the softening temperature of the second ink layer 5 as described above.

The second adhesive Fi6 preferably has a softening temperature of 60 to 130°C, more preferably 70 to 100°C. Further, the second adhesive layer 6 is preferably selected so that its melt viscosity at a temperature 30° C. higher than its softening temperature is 1 to 100,000 cps (according to a rotational viscometer).

The wax component used in the second ink layer 5 is preferably used in the second adhesive layer 6, which is provided as necessary. Further, if necessary, a third adhesive layer (not shown) may be provided on the second ink layer 5 to improve the transfer performance of the ink layer to the recording medium.

In the thermal transfer material of the present invention, it is desirable that the entire ink layer on the support 2 (portion other than the support 2) has a thickness of 20 μm or less. In addition, the first ink layer 4, the second ink layer 5, the first
The thickness of the adhesive layer 3 and the second adhesive layer 6 is preferably in the range of 0.1 to 10 μm.

The colorants used in the first and second ink layers include carbon blank, nigrosine dye, lamp black, Sudan black SM, alkali blue, first yellow, benzidine erotic pigment yellow, India first orange, and irgazine. Red, Varanitroaniline Red, Toluidine Red, Varanitroaniline Red, Carmine FB, Permanent Bordeaux FRR, Pigment Orange R, Lysol Red 20, Lake Red C50-Damine FB, Rhodamine B Lake, Methyl. Violet B Lake, Phthalocyanine Blue Pigment Blue Brilliant Green B1 Phthalocyanine Green, Oil Yellow GG,
Zapon First 20-0GG, Kayaset Y963
, Kayaset YG, Sumi Blast Yellow〇〇, Zabon First Orange RR, Oil Scarlet, Sumi Blast Orange 01 Orazole Brown B, Pomelo First Scarlet CG.

Eisenspiron Red BEH, Oil Pink OP,
Victoria Blue F4R, First Gen Blue 500
7. All known dyes and pigments such as Sudan Blue and Oil Peacock Blue (combine two or more types if necessary)
can be used. In addition, metal powders such as copper powder and aluminum powder, mineral powders such as mica, etc. can be used as coloring agents. Furthermore, as other additives, plasticizers, mineral oils, vegetable oils, etc. may be appropriately added to the ink layer or the adhesive layer.

In manufacturing the thermal transfer recording medium of the present invention, it is preferable to add a dispersant such as a surfactant to the materials constituting each layer to form an aqueous emulsion, which is then mixed and coated.

Also, depending on the materials constituting each of the layers mentioned above, for example, these materials may be mixed with an organic solvent such as methyl ethyl ketone, xylene, or tetrahydrofuran to create a coating solution and each layer may be applied sequentially, or the materials constituting each layer may be heated and melted. So-called hot melt coating may also be performed in the molten state.

Furthermore, using the above method, it is also possible to coat each layer by a different method.

However, the first adhesive layer 3 is preferably applied by dispersing fine particle wax in an adhesive component, or by adding a dispersant such as a surfactant to form an aqueous emulsion. This is to fully bring out the characteristics of the above-mentioned fine particle wax.

A thermal transfer recording method using the thermal transfer material of the present invention will be described below. In the following, a case will be explained in which the most typical heat source is a super-maru head. Further, in the following description, a thermal transfer material having the structure shown in FIG. 2 and having the characteristics shown in FIG. 3 is used as an example of the thermal transfer material.

FIG. 4 is a schematic cross-sectional view in the thickness direction of the heat-sensitive transfer material showing an outline of the case where the second ink layer 5 is transferred. In FIG. 4, 1 is a thermal transfer material, 7 is a thermal head, 7a is a heat generating part of the thermal head, 8 is a recording medium, and 9 is a platen.

Now, a case where the first ink layer 4 is black and the second ink layer 5 is red will be described. FIG. 4 shows the state after recording, in which the thermal head 7 moves eight times to the right (in the direction of the arrow), the thermal transfer material 1 is wound up on a reel (not shown), and the thermal transfer material 1 is removed from the recording medium 8. A state in which the film is peeled off immediately after passing through the heater portion 7a of the thermal head 7 is shown. Immediately after peeling corresponds to time t+ (F+>F2) in FIG. As a result, a red recorded image 5a is obtained on the recording medium 8 based on the selective transfer of the second ink layer 5.

FIG. 5 is a schematic cross-sectional view in the thickness direction of a heat-sensitive transfer material showing an outline of the case where both the first ink layer 4 and the second ink layer 5 are transferred. The difference from the example shown in FIG. 4 is that the thermal transfer material 1 is heated, and after the recording medium 8 and the thermal transfer material 5 run idle for a certain distance while being in close contact with each other, a press is applied to separate them. This is the point where the member 10 is provided.

The pressing member 10 is provided, for example, on a carriage (not shown). This pressing member 10 moves in conjunction with the thermal head 7 while maintaining a certain distance, and moves back and forth as necessary (
In other words, the distance from the recording medium 8 to the recording medium 8 changes. That is, if this member 10 is moved backward, the fourth
As shown in the figure, immediately after the thermal head 7 passes, the thermal transfer material 1 is peeled off from the recording medium 8. On the other hand, when this member 10 protrudes forward, as shown in FIG. after applying 9!1JlliI! to the thermal transfer material 1. It will take longer to do so. For this reason, the adhesive force F1 between the first ink layer 4 and the support 2 is preferably 1.0 to 10.0 g.
/cm, which is smaller than the adhesive force F2 between the first ink layer 4 and the second ink layer 5. Therefore, the thermal transfer material 1 and the recording medium 8 are separated immediately after the pressing member 10, and both the first ink layer 4 and the second ink layer 5 are transferred, and a black recorded image 4a is obtained on the recording medium 8. .

In the above description, the thermal head 7 has been used as an example of the heat applying means, but the heat applying means is not limited to the thermal head 7, and for example, a light source such as a laser beam may be used. Alternatively, if the support is a resistive layer and the ink layer contains conductive powder, electrical transfer recording using a recording electrode needle (stylus) is also possible.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

The volume of the dispersion, the softening point, the glass transition point, and the melt viscosity all indicate the values for the solid content. ) Each component of the above formulation was thoroughly mixed to prepare Ink 1. This ink 1 was applied onto a polyethylene terephthalate (PET) film having a thickness of 3.5 μm and dried at 60° C. to form a first adhesive layer having a thickness of 0.5 μm.

Ink 2> was produced. This ink 2 was applied onto the previously provided first adhesive layer and dried at 80° C. to form a first ink layer with a thickness of 2 μm.

Ink 3> 65 parts of an aqueous dispersion of polyethylene monoxide wax was prepared. Coating this ink 3 on the previously provided first ink layer,
A second ink layer having a thickness of 2 μm was provided by drying at 80° C. to obtain a thermal transfer material (1) shown in FIG. 1.

Ink 4 was produced. Example 1 (thermal transfer material (I))
) The thermal transfer material (I
I got it.

Ink 5〉 was produced. The process was repeated in the same manner as in Example 1, except that this ink 5 was applied instead of ink 3 used in the thermal transfer material CI of Example 1 to form a second ink layer.
) was obtained.

Example 4 A thermal transfer material (V) was obtained in the same manner as in Example 1, except that a second adhesive layer having a thickness of ink 6> μm was provided.

Comparative Example 1 Ink 7> was produced. This ink 6 was applied to the thermal transfer material (1,) of Example 1.
A thermal transfer material (IV
) was obtained.

Example 5 An aqueous dispersion of paraffin wax (softening temperature: 69° C.) was applied between the first ink layer and the second ink layer of the thermal transfer material (I), and dried at 60° C. to give a thickness of 1. A thermal transfer material (IV) was obtained in the same manner as in Example 1, except that this ink 7 was applied instead of ink 3 used in the thermal transfer material (I) to form a second ink layer.

Comparative Example 2 Ink 8> was produced. A thermal transfer material (■) was obtained in the same manner as in Example 1, except that this ink 8 was applied instead of ink 3 used in the thermal transfer material (1) to form a second ink layer.

Using the thermal transfer materials (1) to (■) produced as described above, printing was performed using a thermal transfer printer (Typester 6 manufactured by Canon Co., Ltd.) equipped with a 240 dot/1 nch thermal head 7 manufactured by ROHM Co., Ltd. I did it. The printing energy was 28 mJ/mm2. This thermal head 7
is from the center of the heat generating part 7a to the thermal head terminal end 7b (fourth
(see figure) was 350 μm, and the moving speed of the carriage (not shown) on which the thermal head 7 and the thermal transfer material 1 were mounted was 50 mm/sec. Further, as the recording paper 8, plain paper with a Bekk smoothness of 20 seconds was used.

Therefore, when rapid peeling occurs (time t1 in Figure 3)
), the time from heat application to peeling was approximately 7 m5 ec. Further, a pressure contact means 10 for peeling off with a delayed time was installed at a position approximately 5 mm from the terminal end 7b of the thermal head. Therefore, when peeling is delayed (time tz in Figure 3), the time from heat application to peeling is approximately 1
It was 00m5ec.

While printing is performed using the thermal transfer materials (I) to (■) in this manner, the transfer start temperature (ml) of the first ink layer and the transfer start temperature of the second ink layer for each thermal transfer material are determined by the measurement method described above. The relationship with temperature (m2) was clarified. This m
, m2 was measured using a hot bench WME type manufactured by Reihold (temperature gradient plate length (effective length) 30
cm) with a temperature gradient of 8°C/cm.

The results obtained are shown in the table below.

Note that the printing results in Table 1 are evaluations when both the first ink layer and the second ink layer were transferred (ie, black printing). When only the second ink layer was transferred (ie, red print), the thermal transfer material (V) gave a clear red print. In addition, black was slightly mixed in the red printing of thermal transfer materials (I) to (l), but this did not pose any problem in practical use.On the other hand, thermal transfer materials (Vl)
The red print in (Comparative Example 1) lacks clarity;
Further, the red prints on the thermal transfer material (■) (Comparative Example 2) were thin and transfer defects occurred.

Also, the position of the pressure contact means 10 is changed to the terminal end 7 of the thermal head.
Even if the distance from b was changed from 2 mm to 20 mm, there was almost no change in the result of printing (black printing).

The meanings of the symbols in the above table are as follows.

O: Clear and good with no "edges" or "r hollows".

xl: “Edge removal” and “R hollow” occurred.

x2: Sufficient print thickness was not obtained and chipping occurred.

As explained above, in the thermal transfer material of the present invention, the first
Since the transfer start temperature (ml) of the ink layer and the transfer start temperature (m2) of the second ink layer to the recording medium are set equal, the " It becomes possible to print in beautiful colors without edges or hollow holes.

Further, when the thermal transfer material of the present invention is used, a print with good edge cutting can be obtained, so that the edge portion of the print does not float and a print with excellent scratch resistance can be obtained.

[Brief explanation of the drawing]

FIGS. 1 and 2 are schematic cross-sectional views in the thickness direction showing an example of the thermal transfer material of the present invention, FIG. 3 is a graph showing the relationship between the passage of time and changes in adhesive force between each layer, and FIG. A schematic cross-sectional view showing a state in which the thermal transfer material of the present invention is peeled off from a recording medium immediately after heating, and FIG. FIG. DESCRIPTION OF SYMBOLS 1...Thermal transfer material, 2...Support, 3...1st adhesive layer, 4...1st ink layer, 5...2nd ink layer, 6...2nd adhesive layer , 7... Thermal head, 8... Recorded object, 9... Platen, 10... Pressing means. Ωl: Figure 1

Claims (1)

[Claims] On the support, from the support side, at least an adhesive layer and a first
An ink layer and a second ink layer are sequentially provided, and
The transfer start temperature (m
_1) and a transfer start temperature (m_2) of the second ink layer to the recording medium are substantially equal.