JPS6046296A - Thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To contrive to enhance tone reproduction property, recording sensitivity and preservation stability, by using a basic dye as an image-forming substance, in a thermal transfer recording medium comprising a base, a layer comprising an image-forming substance provided on the base and an image-receiving transfer layer on said layer. CONSTITUTION:A liquid obtained by dissolving or dispersing a binder and a basic dye as an image-forming substance is applied to the base by a coater. Then, the image-receiving transfer layer is provided on the image-forming substance containing layer by coating. The basic dye is transferred from the image- forming substance containing layer to the image-receiving transfer layer in correspondence with the temperature and the period of heating by a thermal head, a laser beam or the like. The binder contained in the image-forming substance containing layer is not transferred onto a recording meidum, and only the image- forming substance and the transfer layer are transferred onto the medium. Accordingly, multiple gradations from a low density part to a high density part can be obtained in accordance with the quantity of thermal energy, and preservation stability is enhanced.

Description

[Detailed Description of the Invention] "Industrial Application Field" The present invention provides a technique for obtaining a transferred image on a transfer recording medium such as plain paper that has rich gradation reproduction and cannot be tampered with. The present invention relates to thermal transfer recording media.

Specifically, the present invention relates to a thermal transfer recording medium which is highly sensitive and can stably obtain sensitivity and gradation even after long-term storage, that is, has good storage stability.

[Prior Art] Conventionally, thermal transfer recording media, in which an image is transferred onto plain paper using a thermal printer, thermal facsimile, etc., use heat-fusible substances containing pigments or sublimation dyes to form a transferred recording medium by heating. Methods of forming an image on a medium by melting, sublimating, or volatilizing are known.

It has also been reported that a color forming agent and a color developer are added to a heat-melting material to develop and transfer color when heated. but,
When a sublimable dye is used, the dye density of the transferred image may change not only before recording but also after recording due to the sublimation property of the dye, which has the disadvantage of poor storage stability. Ta. In addition, the method of transferring by heating a heat-fusible substance containing pigments, etc., has excellent storage stability, but it is said that it is not possible to reproduce tones by changing the optical reflection density per transfer area. There are some woody defects. On the other hand, the heat-sensitive transfer recording medium containing a color former, color developer, etc. described in JP-A No. 56-120393 has a color former and a color developer contained in the same layer, so that it can be used before and after recording. All of them suffer from the drawbacks of being easily colored by light, acids, alkalis, pressure, etc., and having poor storage stability.

The present inventors previously proposed a technique described in Japanese Patent Application Laid-Open No. 57-217063 (hereinafter referred to as the previously proposed technique) in order to solve the drawbacks mentioned in section 2. The previously proposed technology is a thermal transfer recording medium that has a layer containing a foreign dye as an image-forming substance and an image-receiving transfer layer on a support, and has the effect of improving transfer density and thermal stability during storage. I was able to do quite well. As a result of continuing research on the previously proposed technology, the present inventors discovered the following. In other words, when using sublimable dyes as image-forming substances, it is difficult to simultaneously and fully satisfy both the second performance of recording, high sensitivity and storage stability. In order to achieve this, it is necessary to use dyes with high A-flowering properties, but in that case, storage stability inevitably deteriorates, and conversely, sublimable dyes with good storage stability have low sublimation properties, resulting in poor recording sensitivity. There remained dissatisfaction in this respect.

[Object of the Invention] The first object of the present invention is to provide a thermal transfer recording medium that forms a transferred image on plain paper etc. with rich gradation reproduction and which cannot be tampered with. An object of the present invention is to provide a heat-sensitive transfer recording medium that has high recording sensitivity and excellent storage stability.

[Summary of the Invention] As a result of intensive research, the present inventors have developed a layer containing an image-forming substance on a support and an image formed by transferring the image-forming substance to a recording medium using thermal energy on the layer above the layer. The inventors have discovered that the above object can be achieved by using a basic dye as the image forming substance in a thermal transfer recording medium having a receiving transfer layer, leading to the present invention.

[Structure of the invention] The present invention will be described in further detail below.

Various dyes are known as organic compounds that show strong absorption in the visible region, and are substances that adhere to substrates such as fibers in some way and have fastness against sunlight. , (1) direct dyes, (2) acid dyes, (3) basic dyes, (4) medium dyes, (5) architectural dyes, (6) sulfur dyes, (7) soluble vat dyes, (8) naphthols. They are classified into dyes, (8) reactive dyes, (10) cationic dyes, (11) disperse dyes, (12) oxidative dyes F1, etc., and are used depending on the various dyeing methods. The present inventors discovered that a specific dye among these dyes, that is, a basic dye,
It has been found that this dye exhibits significantly more effective effects than other dyes in relation to the objects of the present invention.

Basic dyes preferably used as the image forming substance of the present invention include, for example, crystal violet (C, T,
42555), malachite green (C, T.

42000), methyl violet (C, 1,4253
5), Victoria Blue (C:, 1.44045)
, Mazienta (C,I.

triphenylmethane dyes such as 42510), diphenylmethane dyes such as auramine (C:, 1.t (55)), astraphloxin FF (C, 1, 48070)
, Eisen Carotene Yellow 3GL) I (Hodogaya Chemical Co., Ltd. product, C, 1°48055), Eisen Carotene Red 8BH (C, 1,48020) Astrazone Golden Yellow GL (Bayer Inc. product, C, 1,480
54), methine and azamethine dyes such as Rhodamine 7B (C, 1,451?O), Rhodamine 8G (
Xaten dyes such as C:, 1.451EIO), thiazole azo and triazole azo dyes such as Astrazon Blue-GL (C, 1,11052), Astrazon Red F3BL (G, 1.11055), Eisen carotene blue 5GH (C, 1, 11085),
Xatene dyes such as Methi L/7butAy-(C,1,52015), GTLH (C,1,11085), Cevron Yellow 3R1, (DuPont product, C,1,11087'),
Examples include insulating azo dyes and anitraquinone dyes having an onium group at the structural end, such as Astrazone Blue FGL (C, T, 81512).

In the image forming substance of the present invention, such basic dyes can be used alone or in combination of two or more, and dyes or pigments other than basic dyes can be used in combination with the basic dyes to the extent that the effects of the present invention are not impaired. I don't mind.

Supports that can be used in the present invention include paper, plastic, metal, etc., which can be used for a short period of time at heating temperatures at which the image forming material of the present invention is transferred to the image receiving transfer layer and transferred to the transfer recording medium such as plain paper. Any material may be used as long as it does not soften when heated for a long period of time, particularly any material that does not soften when heated for a short time at about 200'C or less, and condenser paper, polyethylene terephthalate film, and aluminum foil are particularly preferably used.

The thickness can be determined depending on the material of the support, etc., but in general, if it is less than 3 μm, it will be difficult to coat a layer containing the image forming substance of the present invention, and if it exceeds 40 pm, there will be problems in terms of thermal efficiency. Since this is disadvantageous, a thickness of 3 to 40 μm is desirable.

In the thermal transfer recording medium of the present invention, the layer containing the image-forming substance contains a binder to which the basic dye as the image-forming substance can migrate when heated, and the layer contains a binder to which the basic dye as the image-forming substance can migrate on the recording medium to be transferred when heated. are not substantially transferred. This layer may contain substances that assist the basic dye present in the migration upon heating. Examples of the binder forming this layer include casein, gelatin (including derivative gelatin), polyvinyl alcohol, polyvinyl butyral, methylcellulose, gum arabic, polyester,
Generally known binders such as polyvinyl formal, polypropylene, polystyrene, polyvinyl chloride, ethyl cellulose, acetyl cellulose, nylon, and polyethylene (PET), which are thermally stable, are preferred.

The heating temperature when heating the thermal transfer recording medium of the present invention for transfer recording can be determined by taking into account the relationship with the heating time and the melting point of the substance used in the image receiving transfer layer, but it may be higher than room temperature. The temperature is preferably about 45 DEG C., more preferably about 45 DEG C. or higher.

The composition of the image-forming substance-containing layer in the present invention is as follows: binder 5
7 oz (weight ratio, the same applies hereinafter), the basic dye as the image forming substance is preferably in the range of 1 to 90X, particularly preferably 3
0 to 6 oz, basic dye as imaging substance 40 to 7
A proportion of 0% is advantageous. If necessary, additives such as a transfer aid substance for assisting the transfer of the basic dye may be added.

The material forming the image receiving transfer layer in the thermal transfer recording medium of the present invention is a material that can accept a basic dye and transfer to the transfer recording medium, for example, a material that is solid at room temperature and has a melting point that can be melted when heated. For example, a substance with a low melting point (melting point: 45°C!-120°C), or a polymer compound with a softening point of 45°C to 120°C, which can be used in the present invention. Examples include 8'l-r flexible materials such as waxes, higher alcohols, and higher fatty acids known in the art. Specifically, paraffins, carnapa wax, beeswax, ceresin wax, polyethylene wax, amide waxes such as oleenamide, stearylamide, etc. are used singly or in combination of two or more, taking into account their melting temperatures.

One method of recording on a transfer recording medium using the thermal transfer recording medium of the present invention is to use a device that can generate heat, such as a thermal head, a thermal pen, or an iron, to coat the image-forming substance-containing layer of the support. This means heating from the uncoated side.

Using the thermal transfer recording medium of the present invention, various types of paper such as coated paper and drawing paper, polyethylene terephthalate film,
A transferred image can be recorded on any transfer recording medium such as a resin film such as a polyimide film.

In the present invention, the heat-sensitive transfer recording medium of the present invention can be obtained by coating an image-forming substance-containing layer and an image-receiving transfer layer on a support as follows. First, the image-forming material base J layer is coated by l±1, for example, a solution in which a basic dye as an image-forming material is dissolved or dispersed in a solution containing the above-mentioned binder, or a solution is used for binding without using a solution. The basic dye is dissolved or dispersed in the heated and melted agent,
This liquid may be applied onto the support using a commonly known coating device such as a wire bar, brush, or coater. At this time, in order to improve the adhesion between the support and the image-forming substance-containing layer, a so-called undercoat layer may be coated between the support and the image-forming substance-containing layer. Furthermore, a so-called protective layer may be applied as necessary.

[Function of the invention] One preferable usage example of the thermal transfer recording medium of the invention is as follows:
That is, the basic dye is transferred from the image-forming substance-containing layer to the image-receiving transfer layer by a thermal head, a thermal pen, a laser beam, etc. in accordance with the heating temperature and heating time. At this time, the basic dye is transferred together with the low-melting point substance contained in the image-forming substance-containing layer. The binder of the image-forming substance-containing layer is not transferred onto the transfer recording medium, and only the image-forming substance and the image-receiving transfer layer, which have been transferred as a function of thermal energy, are transferred. Therefore, the optical reflection density of the transferred recorded image according to the present invention is determined by the amount of image-forming substance that has migrated to the image-receiving layer. That is, when recording a transferred image using the thermal transfer recording medium of the present invention, an advantage is that not only can halftones be expressed by the area ratio of halftone dots, but also by so-called density modulation. There is. In the present invention, although the mechanism by which the image-forming substance is transferred from the image-forming substance-containing layer to the image-receiving transfer layer is not clear, a visible image is formed on the surface of the recording medium to be transferred by heating with a thermal pen or the like.

[Example] Preferred examples of the present invention are shown below, but the present invention is not limited thereto.

Example 1 On a 5.8 gm polyethylene terephthalate film support, a solution in which the image forming substances shown in Table 1 below were dispersed in the gradations shown in the same table was applied to a dry film thickness of 1.8 gm. An image-forming substance-containing layer was formed by coating the image-forming substance-containing layer using a wire bar so that the image-forming substance-containing layer had the following properties: OpLm. An image and a receiving and transferring layer were formed by coating to a dry film thickness of 2.0 km.

Table 1 Basic dye A C, 1, basic violet 7 (C:, 1.48
020) Basic dye B Basic dye C C, r, Hesikki x mouth l l (C, T, 480
55) Basic dye D G, 1. Basic Yellow 28 (C:, T, 480
54) Basic Dye IER Flower Disperse Dye F Sublimable Disperse Dye G The following heat-sensitive transfer recording test was conducted on each sample of the obtained heat-sensitive transfer recording medium. That is, the coated surface of the sample and the recording medium to be transferred (plain white paper with Beck smoothness of 500) were stacked facing each other, and a thermal transfer recording test was conducted from the support side of the sample using a thermal head (driver-equipped type). .

The recording conditions were as follows, and each sample was tested twice: immediately after its preparation and after it was left at 25° C. and 140XRH for one month.

Recording conditions Applied power (w/dat) 0.4 Applied pulse period (us) 400 Applied pulse I]uty (%) 50 Line period (ms), 25 Paper feeding speed (mm/s) 7.7 Platen pressing pressure ( Kg) 5 After recording, the reflection density was measured. The results are shown in Figures 1 to 7.
It was as shown in the figure.

FIGS. 1 to 5 are graphs showing the relationship between the amount of heating energy and the transfer density for samples N011 to 5 of the present invention, and FIGS.
This is a graph showing the relationship between the amount of heating energy and the transfer density for O, B, and 7. As is clear from Figs. 1 to 5, the density increase Δ at 0.8QIJ after being left for one month is
11 is sample NO, 1 is -0,02, NO32 is -0,
01, N003 is +0.02, N094 is -0,01,
N005 is -0.03, and according to the present invention, it is possible not only to obtain rich multi-gradation from low density areas to high density areas depending on the amount of thermal energy, but also to have excellent storage stability. It can be seen that a thermal transfer recording medium is obtained. On the other hand, as is clear from Figures 6 and 7, 0.0% after being left unused for one month.
The density increase at 8 mJ was +0.35 for sample N096, and +0.4 at 1.5 + wJ for sample N007, and comparison trial I using an image forming substance other than the present invention lacked storage stability. (See Figure 6), or if an image forming substance other than the present invention with good storage stability is used, high density areas cannot be obtained and gradation reproducibility is lacking (see Figure 7). .

[Brief explanation of the drawing]

1 to 5 are graphs showing the relationship between the amount of heating energy and the transfer density for samples Nos. 1 to 5 of the present invention, and FIGS. 6 and 7 are graphs showing the relationship between the amount of heating energy and the transfer density for samples No.
7 is a graph showing the relationship between the amount of heating energy and the transfer density for No. 86 and No. 7. (1 other person) Fig. 1 Jinf Iru V Shitreiri”-(mJ) Fig. 2 Unami tIs*+Regi'-(mJ) Fig. 3 (P Sero 5・Koku 1 Shiku'-(mJ) !4 Drawing number f City Rossi) 1 *'-(mJ) Fig. 5 f*os-'l+vf-(mJ) @ 6 Fig. 144ozHtxノ一り(-(mJ) Fig. 7 W Tsukuda Makoto'- (mJ) -r″-Flowers Written by Neyama Wang E (spontaneous) December 1980
Month 148 Toku 4th generation, Kazuo Nagamiya Wakasugi 1 N (4+ display Showa 58 Patent - No. 153118 2 Name of the invention Sentence Transcript #Nakutai 3 1hj+tE person 4+; 4'l: Which member is it clear? Name (+27) Konishiroku Photo Industry Co., Ltd. 4th floor closet
〒105 6 Number of inventions increased by amendment 7 Amendment vs. Takaaki 1ill I (detailed explanation of the invention 111) 8 Contents of amendment C1) In the 4th page of the specification, line 13, ``The above purpose is changed to `` I-The purpose of the statement is”.

Claims (1)

[Claims] A heat-sensitive transfer recording medium having, on a support, a layer containing an image-forming substance and an image-receiving transfer layer above the layer that transfers the image-forming substance to a transfer-receiving recording medium by thermal energy, wherein the image-forming substance is basic. A thermal transfer recording medium characterized by being a dye.