JPS61295080A - Heat sensitive transfer material - Google Patents

Abstract

PURPOSE:To enable a high density and clear printing even on a recording medium which lacks surface smoothness, by containing a coloring agent at least in either of the two layers that contain thermoplastic material and consist of the first layer which is dense and of uniform thickness and the second layer which is porous. CONSTITUTION:On a sheet substrate 2, a heat sensitive transfer ink layer 3 is formed from the side adjacent to the substrate, by the first layer 3' which contains a thermoplastic material and which is dense and of uniform thickness, and by tne second layer 3'' which is porous and contains a thermoplastic material. At least either one of the layers 3' or 3'' is made to contain coloring agent. The heat transfer ink layer 3 of the heat sensitive transfer material 1 is closely brought in contact with the recording medium 4, and, if necessary, while being supported from the back of the platen 5, a heat pulse is applied by the thermal head 6, and the ink layer 3 is locally heated corresponding to the desired printing or a transfer pattern. The temperature rise of the heating portion softens the first layer 3' and accelerates separation of the substrate and the ink layer 3 in the whole, and at the same time, the porous material 3'' fusion bonds to the recording medium to transfer and to leave a recorded image (b) thereon.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a thermal transfer material that provides a thermally recorded image with good print quality even on a recording medium with poor surface smoothness.

[Conventional technology]

The thermal transfer recording method has the general characteristics of the thermal recording method, such as the equipment used is lightweight, compact, noiseless, and has excellent operability and maintainability. It is characterized by excellent durability of recorded images, and has recently begun to be widely used.

This thermal transfer recording method generally uses a thermal transfer material formed by coating a sheet-like support with a thermal transfer ink in which a colorant is dispersed in a heat-melting binder. is superimposed on the recording medium so that the thermally transferable ink layer is 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 ink image is formed according to the shape of heat supply.

However, in conventional thermal transfer recording methods, the transfer recording performance, that is, the print quality, is greatly affected by the surface smoothness of the recording medium. In the case of a recording medium with a low hardness, there is a problem in that the print quality deteriorates significantly. For this reason, paper with high surface smoothness is generally used as a recording medium, but paper with high smoothness is rather special, and ordinary paper has irregularities of various degrees due to the entanglement of fibers.

Therefore, in the case of paper with large surface irregularities, the hot melted ink cannot penetrate into the fibers of the paper during printing and adheres only to the convex parts of the surface or the vicinity thereof, resulting in the edges of the printed image being distorted. The image may not be sharp or part of the image may be missing, reducing print quality.

Conventionally, for recording media with poor surface smoothness,
In order to obtain a recorded image with good print quality, for example, by using a heat-melt binder with a low melt viscosity in at least the surface layer, or by increasing the layer thickness of the heat-transferable ink layer, it is necessary to transfer the melt ink to the paper. A method based on the idea of faithfully adhering and penetrating even the fine uneven structure of a recording medium was adopted. However, when a binder with a low melt viscosity is used, the ink layer becomes sticky even at relatively low temperatures, resulting in problems such as decreased storage stability and staining of non-printed areas of the recording medium, resulting in blurring of the transferred image. occurs. When increasing the thickness of the soft transferable ink layer, not only does bleeding increase, but the heat supply from the thermal head also needs to be increased, resulting in a decrease in printing speed.

The inventors of the present invention have applied the molten ink to the fine uneven structure of the recording medium in order to provide high-quality prints on recording media with poor surface smoothness. We have come to the conclusion that there are limits to the idea of faithfully adhering to or permeating, as described below.

FIG. 3 shows an example of a cross-sectional curve measured using a stylus meter for pound paper with relatively poor smoothness (smoothness 12 seconds by Peck smoothness meter). As shown in the figure, the distance from the top of the convex part to the bottom of the concave part of the paper (i.e., the depth of the valley) often exceeds 10μ, and in some cases the width of the concave part exceeds 100μ. vertical and horizontal scales are not uniform). Therefore, for this cross-sectional curve,
FIG. 4 is a superimposed cross-sectional view of a typical thermal transfer material and a thermal head during recording, with the vertical and horizontal scales being approximately the same (in the figure, 1 is the thermal transfer material, and this is the same as the support 2). A thermal transferable ink layer 3 is provided on one surface.
5 indicates the recording medium, and 5 indicates the thermal head.) As can be seen, the four large surfaces are coated with melted ink.
It is impossible to fill it completely. In addition, when printing is performed on a recording medium with poor surface smoothness, as shown in Figure 5, which is an enlarged cross-sectional view of the contact area between the thermal transfer material and the recording medium immediately after thermal transfer, The transfer of the meltable ink is incomplete, and only a portion of the heated part adheres to the convex part of the recording medium or near the ridge, and in addition to the non-heated part a, some of the heated part adheres to the concave part of the recording medium. The part C that is printed remains untransferred, and as a result, the print density may be insufficient or a part of the image (cc part of V) may be missing [2] This may reduce the print quality. Understood. The inventors
As a result of further detailed investigation into the cause of such incomplete transfer, the present invention has been achieved.

[Problems to be solved by the invention]

The present invention solves the above-mentioned problems of conventional thermal transfer materials.
~ While maintaining various thermal transfer performances, it is possible to print with high density and sharpness not only on recording media with good surface smoothness, but also on recording media with poor surface smoothness. This was made in order to provide a heat-sensitive transfer material that can provide

[Means and Effects for Solving the Problems] That is, the heat-sensitive transfer material of the present invention, which was discovered as a means for solving the conventional problems, is that It has a thermally transferable ink layer composed of a first layer and a second layer laminated in order, the first layer containing a thermoplastic material and having a dense and uniform thickness, The second layer is a porous layer containing a thermoplastic material, and at least one of the first and second layers contains a colorant.

When the thermal transfer material of the present invention is used, the porous second layer of the dot part is fused by energy applied from a thermal head, etc., thereby increasing the strength of the dot part to which the applied dot is applied, and the layer in the non-applied part. There will be a difference in strength. Also, the first layer in the applied dot area is thermally melted 2, promoting peeling of the ink layer from the support. Furthermore, the second layer of the application dot section generates adhesive force by contacting at least the convex portion of the recording medium, and in addition, a portion of the melted portion of the first layer passes through the porous structure of the second layer. ,
The adhesion force with the recording medium is η, and the same adhesion force as l: transfer of each red dot to the recording medium is achieved.

[Specific song intervals and examples of the invention]

FIG. 1 is a schematic cross-sectional view in the thickness direction of a configuration example in the most basic aspect of the present invention. That is, when the same elements as in FIGS. 3 to 5 are represented by the same reference numerals, the heat-sensitive transfer plate 1 is usually a sheet-like support 2 containing a thermoplastic H material in order from the side closest to the support, and is dense. First layer 3' with uniform thickness
, and a second layer 3N which is a porous layer containing a thermoplastic material.

The second layer 3'' has, for example, a microreticular porous structure.

In this way, if the pores in the ink layer are evenly distributed in the surface direction of the ink layer among porous materials, when heat is applied, the ink layer at the application part tends to fuse, and when no heat is applied, This is advantageous because the boundary between the two parts becomes sharp and clear recording can be obtained.

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, triacetyl cellulose, polyamide, polyimide, cellophane aluminum, etc. Suitable materials include parchment paper and condenser paper. The thickness of the support is preferably about 2 to 15 microns when considering a thermal head as a heat source for thermal transfer. There are no particular restrictions on its use. In addition, when using a thermal head, a heat-resistant protective layer made of silicone resin, fluororesin, polyimide resin, epoxy resin, phenol resin, melamine resin, nitrocellulose, etc. should be provided on the surface of the support that comes into contact with the thermal head. This improves the heat resistance of the support.
It is also possible to use support materials that have not been previously available.

The first layer 3' is for smooth transfer of the entire thermal transfer ink layer including the second layer 3. When the thermal transfer material is peeled off from the recording medium during transfer recording, it is used as a support or It peels off from the interface with the second layer or causes cohesive failure and peels off within the first layer, effectively causing transfer. In order to act in this way, the melting temperature of the first layer must be between 50 and 1
The temperature is preferably 20°C, particularly in the range of 60 to 100°C.

If the temperature exceeds 120°C, sufficient melting heat cannot be obtained, making it difficult to peel off.

In addition, the melting temperature referred to in the present invention is measured using a high slag flow tester C.
Using FT 500 type, load 10Y, temperature increase rate 2℃/
When calculating the viscosity-temperature curve, the apparent appearance of the sample ink under the conditions of 5 x 103 poise was determined as the temperature that gives the viscosity on this curve.

The ink constituting the first layer 3' preferably exhibits a melt viscosity (rotational viscometer) of 0.5 centipoise to 1000 centipoise, particularly 500 centipoise or less at 150°C.

When the melt viscosity at 150° C. is less than 0.5 centipoise, recorded images tend to be smeared, and when it exceeds 500 centipoise, it becomes difficult to peel off.

In addition, the separation between the heated area and the non-heated area of the first ink layer must be good, and it is desirable that the cohesive force of the first ink layer is low, but this can be controlled in relation to the thickness. The second layer, which is a fine reticulated porous material to be described later, is fused by heat application, and the strength of the dot portions is improved, thereby improving the cutting of the first layer.

The thermoplastic materials constituting the first layer include natural waxes such as spermaceti wax, wood wax, lanolin, carnauba wax, candelilla wax, montan wax, and ceresin wax, petroleum waxes such as mother rough-in wax, and microcrystalline wax. Wax, oxidized wax, ester wax, low molecular weight polyethylene, synthetic wax such as Fischer-Trobsch wax, lauric acid, myristic acid, valmitic acid, stearic acid, behenic acid (7), higher fatty acids, stearyl alcohol, behenyl alcohol, etc. Alcohol, sh.

Esters such as sugar fatty acid esters and sorbitan fatty acid esters, amides such as oleylamide, polyamide resins, polyester resins, epoxy resins, polyurethane resins, polyolefin resins, polyacrylic resins, polyvinyl chloride resins resin, cellulose resin,
Elastomers such as polyvinyl alcohol resin, petroleum resin, phenol resin, polystyrene resin, natural rubber, styrene-butadiene rubber, isozolene rubber, chlorozolene rubber, plasticizer, oil agent such as mineral oil, vegetable oil, etc. are mixed as appropriate, and the melting temperature is adjusted. Also, the melt viscosity at 150° C. is controlled to be within the above range.

The melting temperature of the thermoplastic material constituting the second layer 3' is 60
The temperature range is preferably from 70 to 140°C, particularly from 70 to 140°C.

The melt viscosity is preferably 2 to 1 million centipoise, particularly 500 to 100,000 centipoise at 150°C (rotational viscometer).

If it is less than 200 centipoise, the ink will permeate through the contact area between the second layer of the heat application dot and the convex part of the recording medium, and the ink will easily run out at that area, or the ink will drag into the capillary tube at the contact area of the recording medium. Since the ink solidifies in a fixed form, four parts of the recording medium are likely to be left without ink. 100 again
If it exceeds 10,000 centipoise, the adhesion of the porous layer is insufficient, and adhesion to the recording medium cannot be obtained, resulting in poor transfer.

As for the thermoplastic material used for the second layer, any material that can be used for the first layer can be used, and the composition must be determined so as to satisfy the melting temperature and melt viscosity conditions described above. stomach.

1, the thickness of the first layer is preferably in the range of 01 to 10 μm, and the thickness of the second layer is preferably in the range of 1 to 20 μm.

At least one of the first and second layers 3', 3'' contains a coloring agent. It is preferable that both layers contain a coloring agent, but either one may be used depending on the layer thickness. Furthermore, the above-mentioned melting temperature and melt viscosity conditions are, of course, based on the state in which a colorant or other additives added as necessary are mixed.

As the coloring agent, various dyes and pigments widely used in the field of printing and recording are used.

Specifically, for example, carbon black, nigrosine dye, lamp black, Sudanbuti 228M1 First Yellow G, benzidine yellow, pigment yellow,
India First Orange, Irgazin Red, i
4 Ranitroaniline Rhett, Toluidine Red, Carmine FB, No? - Manente Bordeaux FRR, Pigment Orange R1 Linole Red 2G, Lake Red 0, Rhodamine FB, Rhodamine B Lake, Methyl Violet B Lake, Phthalocyanine Blue,
Pigment Blue, Prilliant Green B1 Phthalocyanine Green, Oil Yellow GJ""J'N Fast Yellow 0GG1 Kayasetsu) Y963, Kayaset YG, Sumishilast Yellow GG, Zapon First Oren & RR, Oil Scarlet, Sumishilast Orange G1 Orazole Brown B1 Zapon First Scarlet) OG-.

Eisensubiron Lep-BEH, Oil Gink O
P1 All known dyes and pigments such as Victoria Sol-F'4R, First Gun Blue-5007, Sudan Blue, and Oil Peacock Blue Hiko can be used.

The content of the colorant is 80% or less for each of the ink layers 3' and 3'', and the content of the colorant is 80% or less for each of the ink layers 3' and 3''.
A range of 80% is suitable. Furthermore, additives such as a dispersant or a filler made of fine metal powder, fine inorganic powder, metal oxide, etc. may be added to the ink layers 1.2 as necessary.

To obtain the thermal transfer material of the present invention, for the first layer,
Melt and knead the above-mentioned thermoplastic material, optionally a colorant and additives using a dispersion device such as an attritor, or knead with a suitable solvent to obtain a thermofusible or solution or dispersion ink; This can be obtained by coating 1 on a support and, if necessary, drying.

The method of manufacturing the second layer 3'' having a fine network porous structure as illustrated in FIG. can be provided.

Ink coated with a thermoplastic material as a main component as described above with a blowing agent such as azoisobutyronitrile, N,N'-dinitroethylenetetramine, or ammonium bicarbonate.
-Method of blending into liquid and heating and foaming 2, Ink coating] 2)Method of blending foaming aids such as surfactants with liquid and 7 applying and drying mechanically foamed coating liquid, composition of ink Coating the thermoplastic material with an ink coating liquid using a mixed solvent of a low-boiling point solvent and a high-boiling point solvent (7. The low-boiling point solvent is first volatilized by heat treatment, and the thermoplastic material is A coating solution in which a thermoplastic material and a coloring agent are dissolved or dispersed in a solvent mainly composed of dimethylformamide is coated on a support, and the solvent is immediately replaced with water to make it insolubilized. There are various methods of precipitation.

The combined volume ratio of the thermoplastic material and optionally contained colorant in this porous volume is preferably 5 to 8.
0%, more preferably 10 to 60%.

The planar shape of the thermal transfer material of the present invention is not particularly limited, but it is generally used in the form of a tie-back printer or a medium-wide tape used in line printers. It is also possible to use heat-sensitive transfer materials in which heat-melting inks of several different tones are applied in stripes or blocks for color recording.

-F The thermal transfer recording method e1 using a thermal transfer material is not particularly different from the normal thermal transfer recording method, but just in case, we will explain the case where a heat source and the most typical thermal head are used. . 2M is a schematic cross-sectional view in the thickness direction of the thermal transfer material showing its outline. That is, thermal transfer material l
The recording medium 4 is brought into close contact with the thermal transferable ink layer 3, and if necessary, from the back side of the recording medium! The ink layer 3 is locally heated in accordance with desired printing or transfer/main turn by applying heat and heat to the head 6 while being supported by the lathe 5. The heated part of the ink layer 3 softens the first layer 3' of the ink layer 3' to promote peeling of the entire ink layer 3 from the support, and transfers the porous layer 3 to the recording medium in a fused state.
~Leave a record image.

Although an example in which a thermal head is used as a heat source for thermal transfer recording has been described above, it is easy to understand that the present invention can be implemented similarly when using other heat sources such as laser light.

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

Example 1 Treatment A Carpin black 10 parts Montan wax 20 parts Low molecular weight oxidized polyethylene 10 parts Paraffin wax 60 parts The formulation of Formulation A above was heated to 100°C (by mixing in a sand mill for 30 minutes) , Carpin black was dispersed 17 to prepare the first layered ink A.

Fresh milk 1 Ethylene-acrylic acid copolymer resin emulsion tn
og (total 95% ethylene, 20% non-volatile content) 50% aqueous ammonium lauryl sulfate solution 433% aqueous ammonium stearate dispersion S25 Chikargan black aqueous dispersion 16 Mix the above formulation B with a foaming machine, foam, and foam. The second laminar ink B with a magnification of 3 was adjusted 17.

Hot-melt coat ink A onto a 6 μm polyethylene terephthalate film using an applicator to a thickness of 2.
A first layer of μm was obtained. Coating liquid B was applied to the first layer using an applicator to a coating thickness of 12 μm, and heat treatment was performed at 110°C for 30 minutes to form the second layer, which is a fine reticulated porous layer. A thermal transfer material was obtained.

When this thermal transfer material was used to print on Mend paper (Peck smoothness: 12 seconds) using CANOWARD 458, very clear print was obtained.

Comparative Example 1 A second layered ink B' was obtained by mixing the formulation B of the example without causing foaming, and a first layer was obtained on a 6 μm polyethylene terephthalate film as in the example, and - above. Coating solution B' is applied to the first ink layer to form a dry film of 4 μm.
A second ink layer having a uniform layer of m was provided to obtain a heat-sensitive transfer material.

When printing was carried out using this thermal transfer material in the same manner as in the example, the printed image had poor edges and edges and was unclear.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view in the thickness direction of one configuration example of the present invention. FIG. 2 is a schematic cross-sectional view of an embodiment of a thermal transfer recording method using the thermal transfer material of the present invention. FIG. 3 is a diagram showing a cross-sectional curve of Gando paper (smoothness 12 seconds by Peck smoothness meter) using stylus 1. FIG. 4 is a schematic sectional view of a conventional general thermal transfer film (support thickness: 6 μm, ink layer thickness: 5 μm) and a thermal head superimposed on the Zend paper of FIG. 1. FIG. 5 is a schematic cross-sectional view of a conventional thermal transfer material and a recording medium after thermal transfer. 1...Thermal transfer layer, 2...Support, 3...Thermal transferable ink layer, 3'...First layer, 3''...Second layer, 4...Recording medium , 5... platen, 6... thermal head.

Claims (1)

[Claims] The first layers are stacked on the support in order from the side closest to the support.
and a second layer, the first layer is a layer containing a thermoplastic material and has a dense and uniform thickness, and the second layer is a layer containing a thermoplastic material and having a dense and uniform thickness. 1. A thermal transfer material, characterized in that it is a porous layer containing a thermoplastic material, and at least one of the first and second layers contains a colorant.