JPH03270968A - Heat sensitive transfer recording medium - Google Patents

Abstract

PURPOSE:To record a plurality of printing colors by one type of heat sensitive transfer recording medium by using polyvinyl butyral resin having specific molecular weight as binder resin, and laminating first and second heat sensitive transfer layers including dyes of different hues. CONSTITUTION:A heat sensitive transfer recording medium 1 is composed by laminating first and second heat sensitive transfer layers 3, 4 on a base sheet 2. The layers 3, 4 are formed mainly of hot melt migratory dye and binder resin, and dyes having different hues are used as the layers 3, 4. As the binder resin, particularly polyvinyl butyral resin is desired. Here, the molecular weight of the polyvinyl butyral resin used for the layer 3 is 250000 or less, and the molecular weight of the polyvinyl butyral resin used for the layer 4 is 60000 or more to be reduced. Thus, since dye molecules in the layer 4 are easily moved in the resin as compared with those in the layer 3, the coloring properties of the layer 4 is improved as compared with those of the layer 3 at the time of transferring.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a thermal transfer recording medium used for forming an image using a signal corresponding to image information using thermal energy from a thermal head or the like.

(Prior Art) As a thermal recording method for recording characters and images using a thermal recording member such as a thermal head, there is a thermal transfer recording medium provided with a thermal transfer layer whose main components are a colorant such as a pigment and wax. A method using .

Conventionally, in thermal transfer recording media used for boat fishing, when printing is done with a thermal head etc. over a thermal transfer sheet, one type of thermal transfer recording medium can only record one print color. However, when printing in other colors, a new thermal transfer recording medium was required.

(Problem B to be solved by the invention) The present invention was made in view of the above situation,
An object of the present invention is to provide a thermal transfer recording medium that can record a plurality of print colors using one type of thermal transfer recording medium.

(!!Means for Solving the Problem) In order to achieve the above object, the present invention provides a thermal transfer recording layer having a thermal transfer layer made of a binder resin containing at least a heat-melting transferable dye on a base sheet. In the medium, the heat-sensitive transfer layer has a first heat-sensitive transfer layer using a polyvinyl butyral resin having a molecular weight of 250,000 or less as a binder resin, and a molecular weight higher than the molecular weight of the polyvinyl butyral resin used as the binder resin in the first heat-sensitive transfer layer. A second thermal transfer layer containing a small polyvinyl butyral resin having a molecular weight of 60,000 or more as a binder resin and a dye having a different hue from the dye contained in the first thermal transfer layer is laminated in this order. shall be.

Hereinafter, the present invention will be explained in detail using the drawings.

The thermal transfer recording medium 1 of the present invention has a first
The bottom of the tank is formed by laminating a heat-sensitive transfer layer 3 and a second heat-sensitive transfer layer 4.

In FIG. 1, the base sheet 2 used in the present invention is a film or paper such as a polyester film, a polyester film, a polystyrene film, or a condenser paper. A polyester film is particularly preferred.

The thickness of the base sheet 2 is preferably 3 to IO μm.

The first heat-sensitive transfer layer 3 and the second heat-sensitive transfer layer 4 mainly consist of a heat-melting transferable dye and a binder resin, and as the heat-melting transferable dye, an appropriate dye is selected depending on melting temperature, light resistance, etc. Ru.

The dyes used in the first thermal transfer layer 3 and the second thermal transfer layer 4 have different hues, and the combination of these two different dyes determines the hue range of the printed color.

The hue range of the printing color ranges from the hue that develops when the dye used in the second thermal transfer layer 4 is transferred, to the dye used in the first thermal transfer layer 3 and the dye used in the second thermal transfer layer 4. The color is limited to the hue that develops when transferred after being melted and mixed.

The proportion of dye contained in the heat-sensitive transfer layer is 10 to 7.
Approximately 0% of heavy lids is desirable.

As a binder resin, a resin that releases a heat-melting transferable dye during transfer is required. Such resins include cellulose, polyester, polyamide, polyvinyl acetal, etc. Polyvinyl acecool resins are preferred, especially polyvinyl butyral resins, in view of their affinity with dyes before transfer, which are not given, and the ease with which dyes are released during transfer when thermal energy is applied.

Here, the reason why the molecular weights of the polyvinyl butyral resins of the first heat-sensitive transfer layer 3 and the second heat-sensitive transfer layer 4 are changed is to change the color development during transfer. That is, by making the molecular weight of the polyvinyl butyral resin used for the second thermal transfer layer 4 smaller than the molecular weight of the polyvinyl butyral resin used for the first thermal transfer layer 3, the dye molecules in the second thermal transfer layer 4 are Since the second thermal transfer layer 4 moves more easily in the polyvinyl butyral resin than the dye molecules in the first thermal transfer layer 3, the second thermal transfer layer 4 has better color development during transfer than the first thermal transfer layer 3. In addition, the molecular weight is 60,000 to 2
The range of 50,000 is suitable for the second thermal transfer layer 4.
The molecular weight of polyvinyl butyral resin used in
If it is smaller than 000, the dye molecules move more easily in the polyvinyl butyral resin, which tends to cause dye precipitation on the surface of the heat-sensitive transfer layer, resulting in instability over time. In this method, a dye and a binder resin are dissolved in a solvent to form an ink for the heat-sensitive transfer layer, and the ink is applied onto the base sheet 2 by an appropriate coating method. Considering the coating suitability at this time, the molecular weight of the polyvinyl butyral resin used as the binder resin is is 250
000 or less is desirable.

In addition, for the purpose of improving coating suitability and coating film properties,
Other binder resins and additives may be added in a dissolved state to the ink for the heat-sensitive transfer layer.

Other binder resins that can be replaced with polyvinyl butyral resin include cellulose resins, but the amount to be replaced is preferably within 20 M% in the polyvinyl butyral resin.

The thickness of the heat-sensitive transfer layer is preferably about 0.3 to 1.5 μm for both the first heat-sensitive transfer layer 3 and the second heat-sensitive transfer layer 4, respectively.

In order to form different print colors when transferred using the heat-sensitive transfer recording medium created in this way, before overlapping the heat-sensitive transfer layer and the heat-sensitive transfer sheet and applying thermal energy,
It is necessary to apply thermal energy to the heat-sensitive transfer layer in a state where the dye in the heat-sensitive transfer layer is not thermally melted and transferred to other members.

By applying thermal energy before transfer, the state of melting and mixing of the dye in the first thermal transfer layer 3 and the dye in the second thermal transfer layer 4 changes depending on the thermal energy. In other words, in the initial state where no thermal energy is applied, 2
Dyes of different hues are not mixed, but are arranged in layers.

On the other hand, when thermal energy is applied to the dye in the heat-sensitive transfer layer so that it can freely melt and transfer, the two dyes with different hues are melted and mixed, so they are uniformly mixed. Present in the thermal transfer layer.

By adjusting and applying this thermal energy to the heat-sensitive transfer layer, the mixing state of dyes in the heat-sensitive transfer layer is changed, and a heat-sensitive transfer layer recording medium having heat-sensitive transfer layers with different dye distribution states is formed. Thereafter, the heat-sensitive transfer layer of the heat-sensitive transfer recording medium and the heat-sensitive transfer sheet are overlapped, and thermal energy is applied so that only the dye in the 4 portions of the second heat-sensitive transfer layer is transferred, thereby creating a difference according to the dye distribution state. This makes it possible to form print colors of different colors. Transferring only the dye in the second heat-sensitive transfer layer 4 can be easily achieved by specifying the molecular weight of the polyvinyl butyral used as the binder resin in the first heat-sensitive transfer layer 3 and the second heat-sensitive transfer layer 4 as described above. Become. Further, an intermediate layer is provided between the first thermal transfer layer 3 and the second thermal transfer layer 4 to reduce the difference in color development between the first thermal transfer layer 3 and the second thermal transfer layer 4 by 11#. You can also do that.

Note that when using a thermal recording member that applies energy by contacting the thermal transfer recording medium, such as a thermal head, the thermal recording member and the base sheet are placed on the side where the thermal transfer layer is not provided on the base sheet. In order to prevent fusion and provide slipperiness, a heat-resistant layer containing cellulose resin, silicone resin, etc. can be provided.

In this way, without using the conventional heat-sensitive transfer recording medium provided with a heat-sensitive transfer layer mainly composed of colorants such as pigments and wax,
Using a heat-sensitive transfer recording medium provided with a heat-sensitive transfer layer made of a binder resin containing a heat-melting transferable dye, transfer is performed after changing the distribution state of two types of dyes in the heat-sensitive transfer layer by applying thermal energy. As a result, a plurality of print colors can be recorded on one type of thermal transfer recording medium.

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

(Example) The following formulation (1
) was applied and dried in an open air at 70°C to form a first heat-sensitive transfer layer having a thickness of 1.0 μm after drying.

Furthermore, a second heat-sensitive transfer ink shown in the following formulation (2) was applied thereon and similarly dried in an oven at 70°C to form a second heat-sensitive transfer layer with a film thickness of 1.0 μm after drying. The bottom shape is . Furthermore, a heat-resistant layer mainly made of silicone resin was provided on the surface of the polyester stretched film on which the heat-sensitive transfer layer was not provided, to obtain a heat-sensitive transfer recording medium.

Prescription (1): Ink for the first thermal transfer layer Prescription (2): Ink for the second thermal transfer layer Here, the polyvinyl butyral resin used in the ink for the first thermal transfer layer of prescription (1) has a molecular weight of about 1300
00, and the polyvinyl butyral resin used in the second thermal transfer ink of formulation (2) has a molecular weight of about 100.
It is 000.

The obtained thermal transfer recording medium was subjected to pulses of 0 m5 ec and 1 m5 ec using a thermal head from the heat-resistant layer side under conditions of a printing voltage of 13 V and a thermal head resistance of 300 Ω.
, 2m5ec were changed and thermal energy was applied.

The heat-sensitive transfer layer of the heat-sensitive transfer recording medium that has been given thermal energy is coated with synthetic paper (Tamago Yuka, Yubo 188) with the following composition.
A thermal transfer sheet coated with a dry film thickness of 7.0 μm (μm) is layered with a thermal transfer sheet, and solid printing is performed using a thermal head under the conditions of a printing voltage of 13 V, thermal head resistance of 300 Ω, and pulse IM of 1 msec (7). Ta.

When the hue of the printed area was measured using a color difference meter, it changed as follows depending on the thermal energy applied before printing.

(Effects) As described above, according to the present invention, it is possible to obtain a thermal transfer recording medium capable of recording a plurality of printing colors using a mechanical type thermal transfer recording medium.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of the thermal transfer recording medium of the present invention. 1: Thermal transfer recording medium 2: Base sheet 3: First heat-sensitive transfer layer 4: Second heat-sensitive transfer layer Patent Application Toppan Printing Co., Ltd. Figure 1 Representative Kazuo Suzuki

Claims (1)

[Claims] (1) A heat-sensitive transfer recording medium having a heat-sensitive transfer layer made of a binder resin containing at least a heat-melting transferable dye on a base sheet, wherein the heat-sensitive transfer layer has a molecular weight of 2.
A first thermal transfer layer using a polyvinyl butyral resin of 50,000 or less as a binder resin, and a polyvinyl butyral resin whose molecular weight is smaller than the molecular weight of the polyvinyl butyral resin used as the binder resin in the first thermal transfer layer and 60,000 or more. A thermal transfer recording medium characterized in that a second thermal transfer layer containing a binder resin and a dye having a different hue from the dye contained in the first thermal transfer layer is laminated in this order.