JPH01238989A - Thermal transfer recording medium - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field 1] The present invention relates to a thermal transfer recording medium to which a recorded image is transferred by heating.

[Prior Art] Conventionally, known transfer recording media include transfer sheets in which a heat-sublimable dye layer is provided on a support, and transfer sheets in which heat-fusible substances and pigments are provided on a support. It is used to form images on sheets.

However, although methods using heat-sublimable dyes have excellent gradation expression in images, they have the drawbacks of low heat sensitivity and poor image storage stability; Although this method has excellent thermal sensitivity and storage stability, it has the drawback of not being able to express gradation.

Therefore, a heat-sensitive transfer recording medium has been proposed in which a structure containing a heat-melting ink component mainly composed of a heat-melting substance and a colorant, which are solid at room temperature, is formed on a support in a microporous structure made of resin. Although the gradation has been improved, it is still insufficient compared to the sublimation thermal transfer recording method.

[Objective 1] The present invention aims to improve the drawbacks of the above-mentioned prior art,
It is an object of the present invention to provide a transfer recording medium from which a high-a degree image with excellent gradation can be obtained.

[Structure] The present invention provides a heat-sensitive transfer material having a structure on a support that contains a heat-melting ink component whose main components are a heat-melting substance that is solid at room temperature and a coloring agent in a microporous structure made of resin. The heat-sensitive transfer recording medium is characterized in that the heat-melting substance is made of molecularly distilled carnauba wax.

In the present invention, the heat-fusible substance and the colorant are retained by the network structure made of the fine porous structure of the resin. This heat-melting substance is melted by heating with a thermal head or the like, and oozes out from between the network structures of the microporous structure of the resin together with the coloring agent, and oozes little by little onto the receiving sheet. At this time, by using molecularly distilled carnauba wax as the heat-melting substance, as in the present invention,
The amount of colorant that oozes out varies depending on the amount of thermal energy applied by a thermal head, etc. By controlling the applied thermal energy, it is possible to change the amount of colorant transferred, and the gradation can be faithfully reproduced. 1 q of sharp, wide-ranging, fine-grained, and clear images
I can do that.

The reason for this is not clear, but carnauba wax molecularly distilled as in the present invention has 1) unstable substances, free alcohols, fatty acids, etc., which are removed by evaporation;
2) The C (differential scanning calorific value) curve has become steeper, resulting in better thermal efficiency; 2) In the recrystallized state after dissolving in the solvent, the crystals can be made into much finer particles than conventional carnauba wax products. ,it is conceivable that.

Here, the level of heating energy varies depending on the type of each material and the thickness of the ink layer, and is a relative value.

The molecularly distilled carnauba wax referred to in the present invention is as follows.

Conventional carnauba wax is molecularly distilled using the already known molecular distillation method (New Experimental Chemistry Course 1 Basic Operations [11 edited by the Chemical Society of Japan, published by Marukubi). That is, high vacuum distillation of about 10-1 to 10-4 mmHg is aimed at, and when such a high vacuum is reached, the molecules evaporated from the liquid surface reach the cooling surface without colliding with the other molecules and condense. It is suitable for distillation purification of polymeric substances because it can be distilled at low temperatures and there is little risk of chemical changes due to collisions with molecules.

Therefore, conventionally, carnauba wax has been often used in melt-type thermal transfer methods, but since it is a natural product, there are large variations in products depending on the region of production, climate, harvest time, etc., and there are many free alcohols, acids and Due to the presence of lactones, etc., there were problems such as large crystals and non-uniformity, but with this molecular distillation, unstable substances, free alcohols, fatty acids, etc. are removed by instantaneous heating in a high vacuum, and 1) DSC The curve becomes steeper and the thermal efficiency is improved.2) Crystals become finer particles.3) Quality is stabilized and uniform between lots.4) There is less heat denaturation such as coloring.5) Characteristics such as reduced odor (especially during dissolution) appear. There is.

As the support used in the present invention, conventionally known films and papers can be used as they are, such as films of relatively heat-resistant plastics such as polyester, polycarbonate, triacetylcellulose, nylon, and polyimide, cellophane, or ft acid paper etc. can be suitably used. The thickness of the support is preferably about 2 to 15 microns when considering a thermal head as a heat source during thermal transfer, but it is preferable to use a heat source that can selectively heat the thermal transferable ink layer, such as a laser beam, for example. There are no particular restrictions in this case. In addition, when using a thermal head, a heat-resistant protective layer made of silicone resin, fluororesin, polyimide resin, epoxy resin, phenolic resin, melamine resin, nitrocellulose, etc. should be provided on the surface of the support that comes into contact with the thermal head. This makes it possible to improve the heat resistance of the support, or to use support materials that could not be used conventionally.

It can also be used for electrical transfer, in which the support is made conductive and a current is applied to the support to generate Joule heat and melt and transfer the ink components.

Although there are no particular limitations on the method for producing the heat-melting ink layer having the above-described structure, the following method is generally used. That is, a heat-fusible substance and a coloring agent,
An ink dispersion (or a solution) is obtained by mixing and dispersing the 19-diameter oil that forms the porosity of the resin with a suitable organic solvent using a dispersion device such as an attritor or a ball mill. Separately, a solution of a thermoplastic resin dissolved in an organic solvent is obtained, mixed with the ink dispersion, and uniformly dispersed using a mixer such as a hole mill. Next, the obtained dispersion is applied onto a support and dried to form a first heat-melting ink layer having the above-mentioned fine structure.
I can't stand it. A wetting agent, a dispersing agent, etc. may be added to the dispersion liquid in order to improve the dispersion of the above-mentioned heat-melting substance, colorant, and oil. Further, if necessary, fillers commonly used in resin coatings of this type can be omitted. The resins constituting the microporous resin structure include vinyl chloride, vinyl acetate, vinylidene chloride, nitrocellulose, cellulose acetate, cellulose acetate, acrylic acid, methacrylic acid, acrylic ester and Thermoplastic resins such as monomers or copolymers of monomers selected from methacrylic acid esters, phenol, furan, formaldehyde, urea, melamine,
It is preferable to use thermosetting resins such as alkyds, unsaturated polyesters, and epoxies.

Alternatively, a material that is incompatible with the resin that forms the porous structure and is soluble in a solvent that does not dissolve the resin is kneaded with the resin and coated on the support to form a resin layer. A transfer layer having the above-described structure can also be obtained by dissolving the substance in the above-mentioned solvent to form a porous resin structure, and then filling the porous structure with thermal transferable ink. .

Although the above-mentioned molecularly distilled carnauba wax may be used, other heat-melting substances 71 as described below may be mixed therein. The mixing ratio is molecularly distilled carnauba wax: 1
It is desirable that 0% by weight or more is mixed.

As heat-melting substances that are solid at room temperature, heat-melting binders that constitute heat-melting inks in ordinary heat-sensitive transfer recording media can be used (for example, Karna's Kuba wax, paraffin wax, Sasol wax, Micro Waxes such as crystalline wax and castor wax include stearic acid, palmitin, laurin, aluminum stearate, stearin W, barium stearate, stearin IG, palmitic acid, methyl hydroxystearate, glycerol monohydroxystearate Highly processed fatty acids such as or their metal salts,
Derivatives such as esters: polyethylene, polypropylene,
Olefin homopolymers or copolymers such as polyisobutylene, polyethylene wax, polyethylene oxide, polytetrafluoroethylene, ethylene-acrylic acid copolymer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, etc. As the material, thermoplastic resins made of derivatives of these or the like are used. These holding materials are used alone or in a mixture of two or more in a proportion of 50 to 200 parts by weight based on 100 parts by weight of the thermoplastic resin constituting the thermal transfer layer.

Specific examples of the color toner include the following.

Examples include dyed rice grains and colored pigments, but Dye H is more preferable as it produces images with gradation characteristics (1q).

Examples of such dyes that do not sublimate include the following direct dyes, acid dyes, basic dyes, mordant dyes, sulfur dyes, vat dyes,
There are azoic dyes, oil-based dyes, etc.

1) Direct dyes: Direct Sky Blue, Direct Black W, etc.

2) Acid dye: Tartrazine, Acid Violet 6
B, Acid Fast Red 3G, etc.

3) Basic dyes: safranin, auramine, crystal violet, methylene blue, rhodamine B1 Victoria blue B, etc.

4) Mordant dyes: Sunchromin Fast Allu HB1 Eriochrome Azurol B, Alizarin Yellow B, etc.

5) Sulfur dye: Sulfur Brilliant Green 4G, etc.

6) Vat dyes: indanthremble, etc.

7) Azoic dyes: naphthol As, etc.

8) Oil-based dye Nigrosin, Spirit Black EB,
Varifast Orange 3206, Oil Black 215
, Butter Yellow, Sudan Blue N, Oil Red B
, Rhodamine B et al.

These dyes are preferably in a dissolved state.

Examples of colored pigments include colored fine particle pigments and monoazo pigments.

Specific colored fine particle pigments are shown below. All are made by Hoechst, and the color index numbers are shown in parentheses.

Permanent Yellow GG, 2 (Pigment Yellow 17), Permanent Yellow DIG Transformer 02
(Pigment Yellow 12), Novopalm Yellow HRO3 (Pigment Yellow 83), Hansa Brilliant Yellow 5GXO2 (Pigment Yellow 74), Permanent Orange RLOI (Pigment Orange 34), Novopalm Red HFG (
Pigment Orange 38), Novopalm Red HF
T (Pigment Red 175), Permanent Lake Red LCLLO2 (Pigment Red 53:
1), Novo Palm Red HF4B (Pigment Red 187), Permanent Carmine FBBO2 (
pigment red 146), permanent lupine [
6B (Pigment Red 57:1), Hostapalm Pink Hytrans (Pigment Red 122),
Reflex Blue R50 (Pigment Blue 61
) Monoazo pigments include compounds represented by the following structural formula.

X-N=N-Y however, X didiazonium salt residue Y dicoupler residue Particularly specific examples of product names include the following.

(1) 5ico Fast Yellow D 13
55 (made by BASF) (2) 5ico Fast
Yellow D 1250 (manufactured by BASF) (
3) The structural formula of Lake Red LC (manufactured by Hoechst) is (4) Lake Red C405 (manufactured by Dainichiseika) (
5) Fast Red 1547 (manufactured by Dainichiseika)
The structural formula is: As long as the oil is incompatible with the above-mentioned thermoplastic resin and is non-volatile, either liquid or semi-solid oil can be used.

Liquid oils include, for example, animal and vegetable oils such as cottonseed oil, rapeseed oil, and whale oil; or motor oil, spindle oil,
Mineral oils such as dynamo oil are used, and as semi-solid oils, for example, lanolin, lanolin derivatives, petrolatum, lard, etc. are used.

This oil is preferably a lanolin Km 4 body oil of the same type as the lanolin derivative wax described above, and more preferably an oil of lanolin fatty acid or lanolin fatty acid ester. Specific examples thereof include Neocoat 0ES-181,0ES -183, LFC-50)
1, LS-3102) 1B (all manufactured by Furukawa Oil Co., Ltd.).

Further, in order to further improve the gradation property obtained by 1q in the present invention, it is also possible to add a gradation control agent to be described later.

In other words, the gradation control agent has better wettability and compatibility with the resin than low melting point substances such as oil and wax, which are the main components of hot melt ink, and is firmly held in the sponge resin structure. It seems that the pore size of the porous structure is delicately controlled to make it smaller. Therefore, even when thermal energy is applied, it is not transferred out, but is retained in the porous structure, and acts as a good gradation control agent by controlling the amount of colorant and ink existing in the surrounding area that transfers. it is conceivable that. In addition, by adding a gradation control agent, the unevenness of the surface increases, the contact point with the receptor becomes smaller, and the effect of preventing scumming is also achieved.

As the gradation control agent, the following are shown as specific examples.

1) Acicular crystal pigment (Japanese Patent Application No. 60-38868) 2) Azo pigment (Japanese Patent Application No. 60-192098) 3) Phthalocyanine pigment (Japanese Patent Application No. 60-168562) Addition of the above gradation control agent The amount is 0.5 per part by weight of dye.
~10 parts by weight, preferably 1 to 5 parts by weight.

In order to maintain the porous resin structure more strongly,
It is also possible to apply an intermediate adhesive layer on the support in advance.

Examples of the intermediate indirect @ layer include so-called plastic resins and plastic resins to which fillers are added.

The receiving sheet may basically be plain paper or synthetic paper, but if necessary, it may be made of the above resins, TiO2, silica, ZnO.
It is also possible to apply a filler containing fillers such as the like on plain paper to facilitate the transfer of the colorant.

[Example 1] Next, the present invention will be explained in more detail with reference to Examples. Note that all parts are parts by weight.

Example 1 Colorant: Ne0ZapOn Blue 807 (BA
SF) 10 parts Hot melt ink: Molecularly distilled carnauba wax 30 parts Lanolin fatty acid oil (OES-183, Yoshikawa Oil) 15 parts Powder
0.5 part liquid paraffin
3 parts of the above heat-melting ink components are thoroughly dispersed in a ball mill at about 90° C. for about 48 hours with a mixed solution of 20 parts of methyl ethyl ketone and 130 parts of toluene.

Next, 300 parts of a 20% by weight vinyl chloride-vinyl acetate copolymer resin solution (10 parts of resin, 20 parts of toluene, 20 parts of methyl ethyl ketone) was added to each of the above ink dispersions, and dispersed in a ball mill for about 1 hour to form a thermal transfer composition. Create a coating for objects.

This paint was applied to the surface of a 6 μm thick polyester film with a silicone resin heat-resistant layer on the inside side using a wire bar, and dried at a drying temperature of 100°C for 1 minute. formed a layer.

The transfer medium thus obtained was stacked so that it faced the synthetic paper on which the ink flowed on the receptor, and an image was recorded from the back side of the transfer medium by changing the heating energy with a thermal head, as shown in Figure 1. A cyan tone characteristic curve was recorded. Furthermore, Table 1 shows the results of evaluating the dot recircularity in the low-concentration area using an optical microscope (200x magnification).

Example 2 Colorant: Neozapon Blue 807 (B
(manufactured by A SF) 10 parts Heat-melting substance: Molecularly distilled carnauba wax 20 parts Carnauba wax No. 1 (manufactured by Noda Wax) 10 parts Lanolin fatty acid oil (OES-183, manufactured by Furukawa Oil Co., Ltd.) 15 parts Dispersant
0.5 part liquid paraffin
Three copies were prepared in exactly the same manner as in Example 1, and an image was recorded. As a result, a cyan tone characteristic curve was recorded as shown in FIG. The low density dot reproducibility is shown in Table 1.

Comparative Example 1 Colorant: Neozapon Blue 80710 parts Heat-melting substance: Carnauba wax No. 1 (manufactured by Noda Wax) 30 parts Lanolin fatty acid oil (OES-183) 15 parts Dispersant 0.5 parts Liquid paraffin 3 parts Example 1 When an image was recorded in exactly the same manner as above, the gradation characteristic curve as shown in FIG. 1 and the low density dot reproducibility shown in Table 1 were obtained.

Comparative Example 2 Colorant: Ne0ZapOn Blue 807
10 parts Heat-melting substance: paraffin wax HNPIO
(Made in Japan Wax) 30 parts Lanolin fatty acid oil (OES-183) 15 parts Liquid paraffin 3 parts The image was recorded in exactly the same manner as in Example 1, and the gradation characteristic curve and Table 1 shows the dot reproducibility in the low concentration area.

From the above results, it is recognized that this example sufficiently increases the saturated image density, improves the reproducibility of low image density parts, and further expands the gradation reproduction.

Table 1 0...fairly uniform △...uniform - The ink oozes out from between the tissues and transfers to the receiving sheet surface, so by controlling the heating energy during transfer, good reproducibility of low image density areas and excellent gradation expression (wide gradation reproduction) can be achieved. The transferred image can be 1q, has a high saturated image density, has good reproducibility, and can obtain full-color images by selecting various dyes.

[Brief explanation of the drawing]

FIG. 1 is a graph showing gradation characteristic curves of Examples and Comparative Examples obtained by recording images by changing heating energy with a thermal head.

Claims (1)

[Claims] In the microporous structure made of resin formed on the support,
A heat-sensitive transfer recording medium provided with a heat-fusible ink layer containing as main components a heat-fusible substance that is solid at room temperature and a colorant, characterized in that the heat-fusible substance is composed of molecularly distilled carnauba wax. Thermal transfer recording medium.