JPH02151487A - Thermal recording medium - Google Patents

Abstract

PURPOSE:To form a printing image on a recording medium with good sensitivity without generating contamination by successively forming a dye-containing heat- meltable layer containing a heat-meltable substance and a heat-diffusible dye and a thermoplastic resin layer containing a thermoplastic resin and the heat-diffusible dye on a support. CONSTITUTION:A dye-containing heat-meltable layer 2 and a thermoplastic resin layer 3 are provided on a support 1 in this order. The dye-containing heat-meltable layer 2 is formed in such a state that diffusible dye is dispersed in a heat-meltable substance and the heat-meltable substance is melted by a slight quantity of heat and the dye is sufficiently diffused to be rapidly transferred to the image receiving layer of a recording medium and a printing image can be formed to the recording medium with good sensitivity. A thermoplastic resin layer 3 contains a thermoplastic resin and a diffusible dye and prevents the contact of the dye-containing heat-meltable layer easily adhered or fused to the image receiving layer of the recording medium with the image receiving layer and enhances the releasability between the dye supply layer (dye-containing heat-meltable layer 2 and thermoplastic resin layer 3) and the image receiving layer and eliminates the fusion of the dye supply layer to the image receiving layer to make it possible to prevent the generation of contamination in the printing image formed to the image receiving layer of the recording medium.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermosensitive recording medium. To be more specific,
The present invention relates to a heat-sensitive recording medium that can form printed images on the recording medium with high sensitivity without causing stains.

[Prior Art and Problems to be Solved by the Invention] In recent years, as a recording method for forming color printed images in video printers and the like, for example, a thermosensitive recording medium having a dye supply layer,
A recording method has been proposed in which a printed image is formed on the recording medium by using a recording medium having an image-receiving layer and applying heat with a thermal head or the like.

The principle of such a recording method is that the dye supply layer contains a dye and a thermoplastic resin, the image receiving layer contains a thermoplastic resin, and the dye is transferred to the recording medium by heat applied to the dye supply layer. The dye migrates to the image-receiving layer of the medium and forms a printed image using the dye that has migrated to the image-receiving layer.

For example, when the dye supply layer contains a sublimable dye as the dye, by applying heat with a heat head or the like,
As the dye supply layer and the g1 receiver layer are melted, the sublimable dye in the dye supply layer is sublimated, and the sublimable dye is transferred to the image receiving layer to form a printed image on the image receiving layer.

In such a recording method, a relatively large amount of heat is required to transfer the dye to the image-receiving layer. Therefore, there is a problem that a printed image cannot be formed with sufficient sensitivity.

Therefore, in order to form a printed image with high sensitivity, generally,
Low-melting substances (plasticizers, etc.) and heat-melting substances (wax, etc.) were added to the dye supply layer.

However, if sufficient sensitivity is obtained, but if a low-melting point substance or a heat-fusible substance is added to the dye supply layer to a certain extent, the dye supply layer may adhere or fuse to the image receiving layer during printing, for example. can be.

Therefore, there is a problem in that the image-receiving layer of the recording medium or the printed image formed on the image-receiving layer may be smudged.

The present invention has been made based on the above circumstances.

That is, an object of the present invention is to provide a heat-sensitive recording medium that can form a printed image on a recording medium with high sensitivity without causing stains.

[Means for Solving the Problems] In order to solve the problems described above, the present inventor has made extensive studies and found that a heat-sensitive recording medium having a dye supply layer with a specific structure is capable of absorbing dyes in the heat-sensitive recording medium. The present invention has been achieved by discovering that it can be rapidly transferred to the image-receiving layer of a recording medium and form a printed image on the recording medium with high sensitivity without causing stains.

The structure of the present invention for solving the above problem is that in a thermal recording medium that transfers a dye to an image-receiving layer of a recording medium and forms a printed image on the recording medium, heat is applied onto a support in order from the support. The present invention is a heat-sensitive recording medium characterized by having a dye-containing heat-fusible layer containing a meltable substance and a heat-diffusible dye, and a thermoplastic resin layer containing a thermoplastic resin and a heat-diffusible dye.

FIG. 1 is an explanatory cross-sectional view showing an example of a thermosensitive recording medium of the present invention.

One of the important points in the thermosensitive recording medium of the present invention is that, as shown in FIG. The purpose is to have the following.

Next, regarding the structure of the thermosensitive recording medium of the present invention, the support,
The dye-containing heat-fusible layer and the thermoplastic resin layer will be explained in this order.

(1) Support The support in the heat-sensitive recording medium of the present invention preferably has good heat resistance strength and high dimensional stability.

Examples of the material include papers such as plain paper, condenser paper, laminated paper and coated paper; polyethylene and polyethylene terephthalate.

Resin films such as polystyrene, polypropylene and polyimide: composites of paper and resin films, metal sheets such as aluminum foil, etc. are all suitably used.

The thickness of the support is not particularly limited and any thickness can be used. The thickness of the support is usually 30 Bm or less, preferably 2 to 30 Bm or less.

A dye-containing heat-fusible layer, which will be described in detail below, is planted on the support.

Dye-containing heat-fusible layer One of the important points in the heat-sensitive recording medium of the present invention is that at least a heat-fusible substance and a diffusible dye are provided between the support and the thermoplastic resin layer described in detail below. An object of the present invention is to provide a dye-containing heat-fusible layer containing a dye.

In the dye-containing heat-fusible layer, the heat-fusible substance is melted by a small amount of heat, the dye is sufficiently diffused, and the dye in the dye-containing heat-fusible layer is quickly transferred to the image receiving layer of the recording medium. , has an action or function of being able to form a printed image on a recording medium with high sensitivity.

It is believed that the above-mentioned action or movement of the dye-containing heat-fusible layer is mainly brought about by the heat-fusible substance contained in the dye-containing heat-fusible layer.

The heat-melting substance is not particularly limited as long as it stably holds the dye when not heated, and melts itself when heated to facilitate the diffusion and transfer of the dye, for example, Plant waxes such as carnauba wax, tree wax, auriculie wax and nispar wax; beeswax, insect wax.

Mention may be made of animal waxes such as cera owl and spermaceti; petroleum waxes such as paraffin wax, microcrystalline wax, polyethylene wax, ester wax and oxidized wax; and waxes such as saw wax such as montan wax, osichelite and ceresin. Furthermore, in addition to these waxes, higher fats such as palmitic acid, stearic acid, margaric acid, and behenic acid: valmityl alcohol, stearyl alcohol, hehenyl alcohol, marganyl alcohol, myricyl alcohol, and eicosanol, etc. higher alcohols; higher fatty acid esters such as cetyl palmitate, myricyl palmitate, cetyl stearate and myricyl stearate; amides such as acetamide, propionic acid amide, palmitic acid amide, stearic acid amide and amide wax; and stearylamine.

Examples include higher amines such as behenylamine and palmitylamine.

The melting point of the heat-melting substance is usually 30 to 120°C, preferably 40 to 110°C.

The heat-fusible substances may be used alone or in combination of two or more.

The content of the thermofusible substance in the dye-containing thermofusible layer is usually 20 to 100%, preferably 30 to 90%.
Ball amount%.

The dye-containing heat-fusible layer contains a diffusible dye.

Usually, the diffusible dye is dispersed in the heat-fusible substance.

The diffusible dye is not particularly limited as long as it can be diffused by heat or has diffusivity by being sublimated or vaporized by heat.

However, since the diffusibility of dye molecules in dyes that change in diffusibility changes depending on their molecular weight, the molecular weight of the diffusible dye suitable for the present invention is usually 80 to 4,
000, particularly preferably 100 to 1
,000. The molecular weight of the diffusible dye is 100
When it is within the range of ~t, ooo, the dye diffusivity becomes particularly good.

Furthermore, in the present invention, since the dye is transferred to the image receiving layer of the recording medium by heat, the dye is easily melted or sublimated (vaporized) by the heat supplied by a heat generating element such as a thermal head. The preferred melting point of the dye changes depending on what kind of device is used to perform thermal recording on this thermal recording medium. If this heat-sensitive recording medium is used in an apparatus, the melting point or vaporization temperature of the dye should be 30 to 3
The temperature is preferably within the range of 00°C, particularly 50-2(
Preferably, the temperature is within the range of 10°C.

In the present invention, the heat-diffusible dye or the dye having the above molecular weight or the above melting point or sublimation (vaporization) temperature is, for example, a leuco dye (soluble vat dye).
, direct dyes, acid dyes.

Basic dye 5f! The dye may be appropriately selected from monomorphic mordant dyes, metal lead salt dyes, sulfur dyes, vat dyes, azoic dyes, disperse dyes, reactive dyes, oxidation dyes, oil-soluble dyes, and the like.

In the present invention, the various diffusible dyes described above may be used alone or in combination of two or more.

When using two or more types of diffusible dyes, if two or more types of dyes with different molecular weights, melting points, or sublimation (vaporization) temperatures are used, the color of the print can be changed depending on the difference in printing temperature. Therefore, for example, by varying the thermal trench supplied by the heating element, two multicolored characters can be created.

A single character such as a symbol can be formed on a heat-sensitive recording medium.

The content of the diffusible dye in the dye-containing heat-fusible layer is usually 5 to 80%, preferably 10 to 50%, based on the entire dye-containing heat-fusible layer.

The dye-containing thermofusible layer in the thermosensitive recording medium of the present invention is
If necessary, a thermoplastic resin, a plasticizer, an inorganic filler, etc. may be contained.

Examples of the thermoplastic resin include ethylene copolymers, polyamide resins, polyester resins, polyurethane resins, polyolefin resins, acrylic resins, vinyl chloride resins, vinylidene chloride resins, cellulose resins, and rosin. resins such as ester gum, rosin maleic resin, rosin phenol resin, and hydrogenated rosin; and phenolic resins, terpene resins, cyclopentadiene resins, and carbonized aromatic resins. It is selected from polymer compounds with a softening point of 50-150°C, such as hydrogen resin.

Examples of the plasticizer include phthalate ester plasticizers, phosphate ester plasticizers, adipate ester plasticizers, sebacate ester plasticizers, azelaic ester plasticizers, citric acid ester plasticizers, Examples include glycolic acid ester plasticizers, trimellitic acid ester plasticizers, phthalic acid isomer ester plasticizers, polyester plasticizers, and epoxy plasticizers.

In addition, other plasticizers include fatty acid esters, fatty acids, silicone oils, modified silicone oils,
Fluorine oil, liquid paraffin, etc. may also be mentioned.

Examples of the inorganic filler include metals, metal oxides, total sulfides, graphite, and carbon black.

The content of the thermoplastic resin, plasticizer, inorganic filler, etc. in the dye-containing heat-fusible layer can be determined as appropriate, as long as it does not inhibit the action of the dye-containing heat-fusible layer. .

Furthermore, the dye-containing heat-fusible layer in the heat-sensitive recording medium of the present invention may contain a heat diffusion aid, a pigment, etc., as necessary, as long as it does not inhibit the action or function of the dye-containing heat-fusible layer. You can.

The thickness of the dye-containing thermofusible layer is usually 0.3 to 5.
．． 0 JLm, preferably 0.5 to 31 Lm.

The dye-containing thermofusible layer can be prepared, for example, by first preparing a mixture of a composition containing at least a thermofusible substance and a diffusible dye, and optionally an organic solvent or water, and using this mixture, for example, It can be formed according to a hot melt coating method, an aqueous coating method, a coating method using an organic solvent, or the like.

One important point in the present invention is that a thermoplastic resin layer containing at least a thermoplastic resin and a diffusible dye is provided on the dye-containing thermofusible layer.

The thermoplastic resin layer in the present invention prevents contact between the dye-containing thermofusible layer, which tends to adhere or fuse to the image-receiving layer of the recording medium, and the receiver layer, and prevents the dye-supplying layer (dye-containing thermofusible layer) This improves the peelability between the image-receiving layer (fusible layer, thermoplastic resin layer) and the image-receiving layer, and prevents the dye supply layer from fusing to the image-receiving layer. , has the effect of eliminating the formation of dirt.

It is thought that the above-mentioned action or function of the thermoplastic resin layer is mainly brought about by the thermoplastic resin contained in the mature plastic resin layer.

Examples of the thermoplastic resin include the same thermoplastic resins that can be contained in the dye-containing heat-fusible layer.

The thermoplastic resins may be used alone or in combination of two or more.

As the thermoplastic resin, it is preferable to select and use one that has better releasability and is less likely to be fused to the image-receiving layer of the transfer medium.

The acid contained in the thermoplastic resin in the mature plastic resin layer is
Usually 50 to 90% by weight based on the entire thermoplastic resin layer
and preferably 60 to 80% by weight.

The thermoplastic resin layer in Kiba IJ+ may contain a silicone mold release agent,
Mold release agents such as fluorine-based mold release agents and surfactant-based mold release agents; antioxidants; ultraviolet absorbers: thermofusible substances that can be contained in the dye-containing thermofusible layer, dyes, plasticizers, It may also contain thermal diffusion aids, fillers, pigments, etc.

The thickness of the thermoplastic resin layer is usually 0.3 to 4 gm.
and preferably 0.5 to 3 gm.

The thermoplastic resin layer is prepared by first preparing a mixture of a heat-fusible substance and a dye, if necessary, with an organic solvent or water;
Using this mixture, for example, hot melt coating method,
It can be formed according to an aqueous coating method, a coating method using an organic solvent, or the like.

-Others- After coating each layer, the heat-sensitive recording medium of the present invention is obtained by performing a drying process, a surface smoothing treatment process, etc. as desired, and cutting it into a desired shape.

The heat-sensitive recording medium thus obtained can be used in the form of a tape or sheet, for example.

The thermal recording method using the thermal recording medium of the present invention uses a recording medium having an image-receiving layer together with the thermal recording medium.

The recording medium is a thermosensitive recording medium having a dye supply layer, and a recording medium having a dye supply layer. In a thermal recording method in which a dye is transferred from the dye supply layer to the image receiving layer to form a printed image on the recording medium using a recording medium having a layer, the method includes: an image receiving layer that can be used in the film; A recording medium can be used.

Note that the image-receiving layer of the recording medium generally forms a printed image by being mixed with the dye that has migrated from the dye-containing heat-fusible layer.

In order to make the dye transferable in the image-receiving layer, it usually contains a thermoplastic resin which itself softens to make the dye transferable.

Examples of such thermoplastic resins include the same thermoplastic resins that can be used for the dye-containing heat-fusible layer and the thermoplastic resin layer. Among these thermoplastic resins, preferred resins include polyester resins, polycarbonate resins, vinyl chloride resins, and polyamide resins.

The thickness of the image receiving layer is usually 0.3 to 30,000 g.
m, preferably 3 to 300 uLm.

The recording medium may include only the image receiving layer, or may include the image receiving layer provided on a substrate.

+iiJ Substrates include papers, resin sheets, metal sheets, and the like.

A thermal recording method using the thermal recording medium of the present invention is not different from a normal thermal recording method using a thermal recording medium having a dye supply layer and a recording medium having an image receiving layer. However, an example will be explained in which the most typical heat head is used as a heat source.

First, the thermoplastic resin layer of the heat-sensitive recording medium and the image-receiving layer of the recording medium are set to v, n, and a thermal head applies four heat pulses to the back surface (outside of the contact surface) of the thermosensitive recording medium or the recording medium.
In addition, if necessary, a heat pulse is applied by a platen from the opposite side of the surface to which the heat head is applied, and the dye-containing thermofusible layer and thermoplastic resin layer corresponding to the desired printing or transfer pattern are locally applied. Heat to.

The temperature of the heated portion of the dye-containing heat-fusible layer of the heat-sensitive recording medium rises, the heat-fusible substance rapidly melts, and the dye sublimates (vaporizes) or diffuses.

Next, the heated portion of the thermoplastic resin l1lk1 layer in the heat-sensitive recording medium quickly transfers the dye sublimated (vaporized) or diffused in the dye-containing heat-fusible layer to the image-receiving layer of the recording medium.

In this way, a printed image is formed on the image receiving layer of the recording medium.

[Example] Next, Examples and Comparative Examples of the present invention will be shown to further specifically explain the present invention.

(Example 1) The following dye-containing thermofusible elbow composition was coated on a 4.5 gm thick polyethylene terephthalate film to a film thickness of 2.0 gm.
am to form a dye-containing heat-fusible layer.

Incidentally, the coating was carried out by employing the HO/ ) melt method using a wire bar.

Material Soaked melting □ Braiding paraffin wax, fist, fist, 40% by weight Kayaseto Blue 714 (manufactured by Nippon Kayaku Co., Ltd.) -30% by weight EVA resin, fist, 25% by weight Polyester resin fist - 5% by weight Next, the composition for the thermoplastic resin layer described below was applied onto the dye-containing heat-fusible layer so that the dry film thickness was 2.0p, m. Apply,
A second heat-softening layer was formed to obtain a heat-sensitive recording medium.

The coating was performed using a coating method using an organic solvent (methyl ethyl ketone).

The heat-sensitive recording medium obtained with 70 fil 1% of nitrocellulose resin, Dobruer 14 (manufactured by Nippon Kayaku Co., Ltd.)... 30 ffi amount % was transferred to a commercially available high-speed serial printer (48 filtrate). The thickness of the film made of the following image receiving layer forming resin is 30 g, m.
Using a recording paper having an image-receiving layer, letters of the alphabet were printed on the image-receiving layer, and sensitivity and staining of the recording paper were evaluated.

The results are shown in Table 1.

Note that sensitivity and stain resistance were evaluated as follows.

Exposure: With the applied energy shown in Table 51, the platen pressure of a high-speed printer is 400g? Printing speed 30cp under N conditions
High-speed printing of s was carried out, and the density of the obtained printed image was evaluated.

In Table 1, the meanings of the symbols are as follows.

○・・・・・・・・・・The density of the printed image is high (reflection 1.
2 or more).

x: There is some fading in the printed image, and the density of the printed image is low (reflection less than 1.2).

Staining of Recording Paper The surface side of the printed image on the recording paper was lightly rubbed with paper, and the staining of the recording paper was visually evaluated.

In Table 1, the meanings of the symbols are as follows.

O...It doesn't get dirty at all.

×・・・・・・It gets dirty if you rub it with paper.

(Example 2) In Example 1 described above, the procedure was the same as in Example 1 except that a dye (Kayaset Red 130) was used instead of the dye (Kayaset Blue 14) used in Example 1. A thermosensitive recording medium was obtained.

Using the obtained thermosensitive recording medium, printing was performed in the same manner as in Example 1, and evaluation was performed in the same manner as in Example 1.

The results are shown in Table 1.

(Comparative Example 1) A dye supply layer was formed by applying the following composition for a dye supply layer on a polyethylene terephthalate film having a thickness of 4.5 gm to a film thickness of 4.0 gm, and a thermosensitive recording medium was obtained. Ta.

The coating was performed using a coating method using an organic solvent (methyl ethyl ketone).

Composition for dye supply layer Nitrocellulose resin: 70 ii% h Yaset Blue 714 (manufactured by Nippon Kayaku Co., Ltd.) 30% by weight Same as in Example 1 using the obtained thermosensitive recording medium Printing was carried out under the following conditions, and evaluation was carried out in the same manner as in Example 1.

The results are shown in Table 1.

(Comparative Example 2) A dye supply layer was formed by coating the following composition for a dye supply layer on a polyethylene terephthalate film having a thickness of 4.57 zm to a film thickness of 4.0 µm, and a thermosensitive recording medium was formed. Obtained.

The coating was performed using a coating method using an organic solvent (methyl ethyl ketone).

Composition for dye supply layer Nitrocellulose resin 111111Il...4 Q f
f1 Abrasive% paraffin wax...30ff
i ffi %h Yaceft Blue 714 (manufactured by Nippon Kayaku Co., Ltd.)...30% by weight Table 1 Using the obtained thermosensitive recording medium, printing was carried out in the same manner as in Example 1; We conducted an evaluation.

The results are shown in Table 1.

(Hereinafter, blank space) (Evaluation) As is clear from Table 1, the heat-sensitive recording medium of the present invention is:
It was confirmed that even during high-speed printing, a good printed image could be formed with high sensitivity, and there was no staining on the recording paper.

[Effects of the Invention] According to the present invention, the dye of the (+) thermosensitive recording medium can be transferred to the image receiving layer of the recording medium with a relatively small a ht.
The dye in the heat-sensitive recording medium quickly migrates to the image-receiving layer of the recording medium, and a printed image can be formed with high sensitivity. It is possible to provide a heat-sensitive recording medium that has the following advantages: good releasability from the image-receiving layer of the recording medium, and the ability to form a printed image on the recording medium without causing stains.

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view showing an example of the heat-sensitive recording medium of the present invention. 1-...Support, 2...Dye-containing heat-fusible layer, 3...
・Thermoplastic resin layer.

Claims (1)

[Claims] (1) In a thermosensitive recording medium in which a dye is transferred to an image-receiving layer of a recording medium to form a printed image on the recording medium, a heat-fusible substance and a heat-diffusible dye are contained on a support in order from the support. 1. A thermosensitive recording medium comprising: a dye-containing heat-fusible layer; and a thermoplastic resin layer containing a thermoplastic resin and a heat-diffusible dye.