JPS63185680A - Thermal transfer material - Google Patents

Abstract

PURPOSE:To enable images with favorable quality free of voids or blur to be transferred even onto an ordinary paper low in surface smoothness, by incorporating a foaming agent capable of foaming at a predetermined temperature into a heat-fusible ink layer on a base. CONSTITUTION:A heat-fusible ink 7 comprises a heat-fusible substance, a coloring agent and a softener, and further comprises a foaming agent 8. The heat- fusible substance is preferably one which has a melting or softening point of 60-120 deg.C, for example, carnauba wax or paraffin wax. The coaming agent is preferably diazoaminobenzene or dinitoropentamethylenetetramine. Where a thermal head is used as a heat source, the foaming temperature of the foaming agent is preferably higher than the melting point of the heat-fusible substance by about 70-400 deg.C. The particle diameter of the foaming agent depends on the thickness of the ink layer or the like, and the diameter of the particles inclusive of liquid particles is several Angstrom 's to several tens of micrometers, in which a relatively smaller particle diameter being more preferable from the viewpoint of resolution.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a thermal transfer material for recording an image by ink transfer using a thermal head.

(Prior Art) Devices using thermal recording methods, such as printers and facsimiles, have features such as being lightweight, producing little noise, and being easy to operate and maintain. However, the heat-sensitive recording paper normally used in such heat-sensitive recording methods is a relatively expensive processed paper, and is easily colored by chemicals or heat (and also has poor storage stability, such as fading over time after recording). For this reason, a thermal transfer recording method in which an image is transferred onto a recording sheet such as paper has recently been attracting attention.

In this thermal transfer recording method, a thermal transfer material 3 is generally used, which is formed by forming a layer of heat-melting ink 2 on a sheet-like support 1, as shown in FIG. In order to obtain good reproducibility, a film or the like having excellent surface smoothness and dimensional stability is used.

Then, heat is selectively applied to the thermal transfer material 3 in contact with the recording sheet 4 using a thermal head 5 or the like, thereby melting and transferring the ink 2 of the thermal transfer material 3 onto the recording sheet 4 to perform recording. In this recording method, the sharpness of the printed image largely depends on the smoothness of the recording sheet 4. For this reason, for example, the Bekk smoothness of rough paper is 2-10.
It would be possible to obtain clear prints on bond paper in seconds,
Conventionally, heat-sensitive transfer materials have been proposed in which a large amount of heat-fusible substances or colorants are dispersed in the ink layer, or an ink transfer layer is provided that includes microcapsules encapsulating ink containing a foaming agent and a binder. (For example, JP-A-58
-59897).

(Problems to be Solved by the Invention) However, with the former thermal transfer material, the thickness of the ink layer becomes large, which tends to cause background smearing and a decrease in resolution.

In the case of the latter thermal transfer material using microcapsules encapsulating a blowing agent and ink, the microcapsule film can be obtained by the usual interfacial polymerization method, interfacial precipitation method, coacelvage treatment method, etc. There is a problem of becoming a membrane.

In such a porous membrane, for example, the polymer substance of the capsule wall membrane undergoes a glass transition due to instantaneous heating by a thermal head during actual transfer, becomes rubbery, expands, and temporarily increases permeability or permeability. As a result, the contents within the capsule may diffuse or permeate to the outside before the foaming temperature of the foaming agent is reached.

Furthermore, when dispersing and mixing the microcapsules in a binder, there is a problem in that a relatively low temperature must be maintained to prevent the ink and the like from diffusing through the capsules. As a result, in these thermal transfer materials,
Use in an appropriate temperature range is required, and if this requirement is not met, it is difficult to obtain sufficient printing sensitivity and there is a problem with recording stability.

The object of the present invention is to eliminate these conventional problems and provide a thermal transfer material capable of transferring prints without white spots or blurring even to the above-mentioned rough paper.

(Means for Solving the Problems) The heat-sensitive transfer material of the present invention is a heat-sensitive transfer material having a heat-melt ink layer on a support. It contains.

(Function) In the thermal transfer material of the present invention, the foaming agent in the ink layer on the support causes foaming when heated by a thermal head, etc., so that the ink uniformly reaches the recesses on the paper surface of plain paper, etc. It forms a high quality printed transfer image.

(Example) FIG. 1 shows the structure of an embodiment of the thermal transfer material of the present invention.

In FIG. 1, the thermofusible ink 7 is composed of a thermofusible substance (
The heat-melting ink layer 7 further contains a foaming agent 8.

Specifically, an ink component consisting of the following composition: carbon black (colorant) 20 parts ethylene-vinyl acetate copolymer (softener) 5//diazoaminobenzene (foaming agent) 0.5// was heated at 90°C. to uniformly disperse the mixture and obtain a coating solution.

This coating solution was coated onto a 6 μm thick support 6, such as a polyethylene terephthalate film, using a wire coater to form an ink layer of 6 μm to obtain a heat-sensitive transfer material. Using this thermal transfer material, printing was carried out on bond paper with a Peck smoothness of about 10, and microscopic van inspection of the resulting transfer prints revealed that the foamed ink had sufficiently reached the paper fibers or the space a. It was confirmed that a good transferred image with few white spots was obtained as a print.

Here, materials that can be used for each component of the ink layer of the thermal transfer material of the present invention are listed below.

The heat-melting substance has a melting point or softening point of 60 to 12
A temperature of 0°C is preferable, and specific examples include petroleum waxes such as carnauba wax, paraffin wax, sasol wax, microcrystalline wax, hollow wax, auriculie wax, ester wax, and oxidized wax, and minerals such as montan wax, oshikerite, and ceresin. Various waxes such as wax, higher fatty acids such as palmitic acid and stearic acid, palmityl alcohol, stearyl alcohol,
Higher alcohols such as behenyl alcohol and eicosatl, higher fatty acid esters such as cetyl palmitate, myricyl palmitinoate, cetyl stearate, myricyl stearate, amides such as acetamide, propionic acid amide, palmitic acid amide, stearic acid amide, ester gum, Rosin Malein [[, Rosin Phenolic Resin,
Phenol! +111, high molecular compounds such as terpene resin, cyclopentadiene resin, and aromatic resin, higher amines such as stearylamine, etc., and these may be used alone or in a mixture of two or more.

Examples of the softening agent include polyvinyl acetate, cellulose esters, acrylic resins, stearic acid, lanolin, etc., and IM or a combination of two or more of them can be selected as appropriate based on their melting or softening temperature. It is used as

Next, as colorants, there are phthalocyanine-based organic pigments, inorganic pigments such as carbon black, and various dyes.
It is selected and used as appropriate.

Specifically, carbon black, nigrosine dye, lamp black, alkali blue, first yellow G, benzine yellow, pigment yellow, indofirst orange, ingazine red, varanitroaniline red, toluidine red, carmine FB. , Permanent Bordeaux FBR, Pigment Orange R1 Linole Red 20, Lake Red C10-Damine FB,
Rhodamine B Lake, Methyl Violet B Lake,
Phthalocyanine Blue, Pigment Blue, Prilliant Green B1 Phthalocyanine Green, Oil Yellow GG, Zapon First Niro GG1 Kayaset Y963, Kayaset YG1 Sumiplast Niro G
G, Zapon Fast Orange RR, Oil Scarlet, Sumiplast Orange G1 Orazole Brown B
1. Known dyes and pigments such as Pomelo First Scarlet CG, Icenos Viron Red, BEH, Oil Pink OP1, Victoria Blue F4R, First Gel Blue 5007, Sudan Blue, and Oil Peacock Blue are used almost without exception.

Foaming agents to be included in the heat-melting ink include sodium hydrogen carbonate, ammonium carbonate, ammonium acetate,
Known blowing agents such as amyl acetate, butyl acetate, diazoaminobenzene, and dinitrosopentamethylenetetramine are used, with diazoaminobenzene and dinitrosopentamethylenetetramine being particularly preferred.

The foaming temperature of these foaming agents is 70°C higher than the melting temperature of the above-mentioned heat-melting substance when the #1 source is a thermal head.
The temperature is preferably about ℃ to 400℃. The particle size varies depending on the thickness of the ink layer, etc., but it is desirable to have a particle diameter of several microns to several microns, including liquid particles, and relatively small particles are preferable in terms of resolution.

Films and paper are commonly used as supports, such as
Resin films such as polyethylene terephthalate, cellophane, polycarbonate, triacetyl cellulose, nylon, or high-quality paper, coated paper, glassine paper, parchment paper, etc. may be used.

The thickness of this support is preferably thin in consideration of thermal conductivity to the ink layer, but it is preferably about 2 to 10 microns especially when the heat source is a thermal head, and in other cases especially There are no restrictions.

In order to actually obtain a thermal transfer material, a liquid mixture consisting of the above-mentioned heat-melting substances, colorants, softeners, foaming agents, etc. is applied onto the above-mentioned support by a method such as solvent coating or hot-melt coating. In this case, the thickness of the coating film is preferably about 3 to 10 μm.

Further, when a thermal head or the like is used as the heat source ζ, it is desirable to provide a heat-resistant protective layer on the surface of the support that comes into contact with the head to improve the heat resistance of the support. As such a protective layer, fluororesin, polyimide resin, epoxy resin, phenol resin, etc. are suitable.

(Effects of the Invention) As described above, the present invention is an ink in which a foaming agent is mixed into a heat-melting ink coated on a support, and when it comes into contact with a heat source such as a thermal head during printing, it instantly Even when the ink foams on plain paper with low surface smoothness, the ink properly reaches the recesses of the paper, resulting in a high-quality transferred image without white spots or blurring, which has the effect of solving the above-mentioned problems. .

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the transfer material of the present invention, and FIG. 2 is an explanatory diagram of a conventional thermal recording method. DESCRIPTION OF SYMBOLS 1...Support, 7...Thermofusible ink, 8...Blowing agent. Figure 1 Figure 2

Claims (1)

[Scope of Claims] A thermal transfer material comprising a heat-sensitive transfer layer formed of a heat-fusible ink made of a heat-fusible substance, a coloring agent, etc. on a support, wherein a foaming agent is mixed into the heat-fusible ink. Characteristic thermal transfer material.