JPS6282085A - Thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To provide a thermal transfer recording medium capable of applying good quality printing to rough paper inferior in surface smoothness, by setting the film thickness of an ink layer containing an aqueous emulsion of a thermoplastic resin to a specific value or less. CONSTITUTION:In a thermal transfer recording mediumm wherein a layer containing an aqueous emulsion of a heat-meltable substance is provided on a support and at least one ink layer containing an aqueous emulsion of a thermo plastic resin is provided thereon, the film thickness of the ink layer is set to 2mum or less. In such a case that the ink layer is formed of the aqueous emulsion, the adhesive strength between the ink layer and paper is slightly lowered as compared with such a case that the ink layer is formed of a solvent system but, because flocculation force is also lowered, this ink layer is extremely advan tageous in a thermal transfer system. If ink formed of the solvent based on a polymer is used, a whisker like stringing phenomenon is easy to generate at the edge part of a printed character but this phenomenon is less significant in the emulsion system. The thickness of the lower layer may be thin but, when thicker than the ink layer, especially good quality printing is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application (2)] The present invention relates to a VA thermal transfer recording medium, and more particularly to a thermal transfer recording medium that provides good quality printing even on rough paper with poor surface smoothness.

[Prior art]

In recent years, there has been a remarkable increase in R1N information processing systems, and with this, recording methods and devices suitable for each system have been developed and adopted. Among these, the thermal recording method is
It is widely used because it is lightweight, compact, silent, and has excellent operability and maintainability.

However, among the recording papers used in thermal recording methods, ordinary thermal recording paper is expensive because it is a coloring type that contains a color former and a color developer, and the recording paper easily develops color due to heat or organic solvents. However, there were also drawbacks in terms of storage stability, such as the recorded image fading in a relatively short period of time.

A thermal transfer recording method has recently attracted particular attention as a method for improving the above-mentioned drawbacks.

In this thermal transfer recording method, normally, on a sheet-like support,
Using a heat-sensitive transfer recording medium having a heat-fusible ink layer in which a colorant is dispersed in a heat-fusible substance, the heat-sensitive transfer recording medium is supported with the ink layer superimposed on a transfer target (generally a layer). By heating with a thermal head from the body side and transferring the melted ink layer to the transfer target U body, an ink image corresponding to the heated shape is formed. By this method %
It has also become possible to record on plain paper, and the drawbacks of the above-mentioned thermal recording paper have been solved.

L tJ'L rj'' (The thermal transfer recording method of La.0 also has the problem that the print quality is affected by the surface smoothness of the transfer medium. Although good printing is achieved, the print quality is significantly reduced when a transfer medium with low smoothness is used. This is a particular problem when using paper, which is the most typical transfer medium. In other words, paper with high smoothness is rather special; ordinary paper has unevenness due to intertwining of fibers, and rough paper with a Bekk smoothness of about 10 seconds has a rough surface from the top of the convex part to the bottom of the concave part. There are parts where the distance is 10 am or more.

When thermal transfer printing is performed using such paper, the print density is low or parts of the print are missing, resulting in a significant deterioration in print quality.

In order to improve this heat transferability, it is possible to use waxes with a low melting point as the heat-fusible substance in the heat-fusible ink layer, but the meltability increases and immersion into the paper progresses, resulting in a substantial bond between the paper and the paper. Although the adhesion area becomes larger, the adhesive strength between the ink layer and the paper decreases as well as the cohesive force of the ink layer, so a sufficient effect cannot be obtained, and the ink layer becomes sticky even at relatively low temperatures, resulting in a decrease in storage stability. It also causes problems such as blurring of printed characters and staining of non-printed areas (background stains). In addition, the adhesive strength of the ink layer to paper is inherently weak, so in order to increase the adhesion area, the thickness of the ink layer must be increased. There is also an 8-bit which increases the size of 9, which causes a decrease in printing speed.

Therefore, there is a need for the development of a thermal transfer recording medium that can improve the above-mentioned drawbacks and can provide good printing even on rough paper with poor surface smoothness.

[Purpose of the invention]

An object of the present invention is to provide a thermal transfer recording medium that can print with good print quality even on rough paper with poor surface smoothness.

[Structure of the invention]

The present inventors conducted intensive research on the relationship between the adhesive force and cohesive force of the ink layer, and found that a layer containing water-based emulsion carbon 3, a heat-melting substance, on a support, and a layer containing a heat-meltable substance, a thermo-degradable Thickness f2a of the ink layer of a thermal transfer recording medium having at least one ink layer containing an aqueous emulsion of a resin
The inventors have discovered that the above object can be achieved by setting it to m or less, and have accomplished the present invention.

The present invention will be explained in more detail below.

When the thermal transfer recording medium and the paper are substantially separated after energy is applied, the ink layer preferably has a strong adhesive force with the paper, a weak adhesive force with the support, and a somewhat weak cohesive force. However, the cohesive force of the ink layer is generally correlated with the adhesive force;
Reminiscence is what satisfies both parties. The inventors ink r
:! 1fr: When formed with an aqueous emulsion, the adhesion force between Ink D and Ink is somewhat lower than when formed with a molten S system, but the binding force is also lowered, and in a thermal transfer system:
= I discovered that it is extremely advantageous. In addition, with solvent-based inks containing polymer as the main component, threading is likely to occur at the edges of printed characters.
This is also less in the emulsion connection system. Furthermore, the temperature at which blocking occurs also increases.

We also discovered that even if the ink layer has a strong cohesive force, if the thickness of the ink layer is reduced, the same effect as when the cohesive force is made weaker by 2 can be obtained, and that the upper limit is 2 μm.

The aqueous emulsion containing the heat-fusible material (referred to as the awn in this application with respect to the ink layer) plays a role in adjusting the adhesion force between the ink layer and the support. Also, when cold, the film adhesion of the ink layer, V! It is preferable to use a material that has good mechanical handling properties such as strength, and weakens the adhesion to ink when heated. The lower layer may be transferred to the recording paper together with the ink layer, but in that case, the cohesive force of the lower layer and the cohesive force of the ink layer will be added, and the ink will be transferred to the recording paper together with the ink layer. Since stronger striking force is required, it is preferable to separate the ink between the lower layer and the ink.

Although the thickness of the lower layer may be thin, particularly good quality printing can be obtained when it is thicker than the ink layer. If the ink layer is good, this is practically the same as one paper! 2nd place The cross-sectional area will be uneven, so it will be less q, but because the bottom layer is thick, this part will absorb the unevenness of the paper,
This is thought to be because the substantial adhesion area between the ink D and the paper is increased. The thickness of Tm is preferably 0.5 to 5 μm.

An aqueous emulsion of a thermofusible substance is used as the Tm of the present invention. The heat-melting substance is preferably a solid or semi-solid substance with a melting point (measured by Sakemoto MPJ-2 model (Ii)) of 40 to 150°C.Specific examples include carnauba wax, wood wax, and ouriquerie. Wax, vegetable wax such as Nispar wax, beeswax, insect wax, animal wax such as Cera 7 Claw, lily wax, paraffin wax, microcrystalline wax, polyethylene wax, ester wax, petroleum wax such as Hiwafukusu, montan wax, osichelite, montan, etc. In addition to waxes such as mineral wax; palmitic acid, stearic acid, margaric acid,
Higher fatty acids such as behenic acid; higher alcohols such as haloalfur, stearyl alcohol, behenyl alcohol, marganyl alcohol, myricyl alcohol, and eicosa/-al; 7000 palmitate, myricyl palmitate, stearic acid, stearic acid Amides such as higher fatty acid ester nia-heptamide such as myricyl, propionic acid amide, palmitic acid amide, stearic acid amide, amide wax; rosin derivatives such as ester gum, rosin maleic acid aim, rosin phenol taU, hydrogenated rosin; phenolic resin , terpene resin, cyclopentadiene, polymer compounds with a recovery point of 50-150°C, such as cyclopentadiene, cyclopentadiene,
Higher amines Wi such as behenylamine and palmythylamine
These may be used alone or in combination.

In order to form a hot-melt substance into an aqueous emulsion, it may be emulsified in water using an existing method such as a phase inversion method, a high-pressure emulsification method, or an ultrasonic dispersion method using a system containing an emulsifier.

The emulsifier may be any of anionic, anionic, cationic, and amphoteric emulsifiers. Further, in order to obtain the ability to form a film on the support when cold, etc., an aqueous emulsion of a thermoplastic resin may be appropriately mixed with an aqueous emulsion of a thermofusible substance.

Furthermore, in order to reduce the adhesive force with the ink layer when heated, a substance that acts as a release agent may be appropriately mixed and used.

Next, the thermoplastic resin used in the -f layer of the present invention will be explained. Thermoplastic resins include polyamide resins, polyester resins, polyurethane resins, polyolefin resins, acrylic resins, vinyl chloride resins, cellulose resins, rosin resins (oil oil, petroleum-based T, B fat, ionomer resins, natural Examples include elastomers such as rubber, styrene-butadiene rubber, imprene rubber, and chloroprene rubber IJ.

The aqueous emulsion of the thermoplastic resin can be obtained using exactly the same method as for producing an aqueous emulsion of a thermofusible material, or by a conventional emulsion polymerization method. Also, a fairly wide range of aqueous emulsions are commercially available. A second specific example is given below.

0 Polysol AP-691 (2-handle hexyl acrylate type) Showa Kobunshi 0 Nifbol LX-811 (acrylic ester type)
Nippon Zeon Omonylin I) M-60 (styrene-acrylic acid group)
Hoechst Chemical Co., Ltd. JSR-2108 (Screen-fixed diene type) Japan Synthetic Rubber 0 Pyronal MD-1200 (Polyester type) Toyobo 0 Chemivar S-100 (Ionomer type) Mitsui Petrochemical oAD-37F1 (Polyethylene type) Toyo Ink 0 Zaik 7 Ninjin (acrylic acid based) Steel Chemical 0 Panflex C1-5000 (vinyl acetate based) Kuraray Q Hallinister DS-90E (Ogin based T31 fat) ff? The coloring agent used in the ink composition of the present invention may be any of pigments, organic pigments, and organic dyes. Examples of inorganic pigments include titanium dioxide, carbon black, zinc ffi, Prussian blue, cadmium sulphide, iron oxides and chromates of lead, zinc, barium and calcium. Organic pigments include azo, thousand oindigo, and anthraquinone.

Anthurone, triphenedioxazine pigments,
These include vat dye pigments, phthalocyanine pigments such as copper-7 thalocyanine and its derivatives, and quinacridone pigments.

Examples of organic dyes include acid dyes, direct dyes, disperse dyes, oil-soluble dyes, and metal-containing oil-soluble dyes.

In the present invention, the composition ratio of the components forming the ink layer is not limited, but the colorant is 5 to 40 parts by weight (more preferably 5 to 35 parts by weight), It is preferable to use the plastic resin in an amount of 5 to 95 parts by weight (more preferably 1 to 90 parts by weight).

In addition to the above components, the ink layer of the present invention may contain various additives. For example, thickeners such as sodium polyacrylate to adjust the viscosity of the aqueous emulsion, and substances to improve surface slippage such as floidal silicide may be used.

Anionic, cationic, /ionic, and amphoteric surfactants are also preferably used.

The support used in the thermal transfer recording medium of the present invention preferably has heat-resistant strength, high dimensional stability, and high surface smoothness. Examples of materials include papers such as plain paper, condenser paper, laminated paper, and coated paper; resin films such as polyethylene, polyethylene terephthalate, salistyrene, polypropylene, and polyimide; and paper-resin film composites, aluminum foil, etc. Metal sheets and the like are preferably used. The thickness of the support is usually about 60 μm or less, particularly 1.5 to 1.5 μm, in order to obtain good thermal conductivity.
Preferably, it is 15 μm. Furthermore, in the thermal transfer recording medium of the present invention, the structure on the back side of the support may be optional, and a packing layer such as a stinking prevention layer may be provided.

A method for thermal transfer recording using the thermal transfer recording medium of the present invention will be described below.

The component layer surface of the thermal transfer recording medium of the present invention and a recording sheet such as plain paper are overlapped, and depending on the image information, a thermal recording device using a thermal head, a thermal pen, or a laser is used to print from the thermal transfer recording medium side and/or When energy is applied from the recording sheet side, the ink layer adheres to the recording paper due to the application of relatively low energy, and when the thermal transfer recording medium is substantially separated from the recording paper, the ink layer is transferred to the recording paper.

〔Effect of the invention〕

By using the thermal transfer recording medium of the present invention, the following effects can be obtained.

(1) High density and clear printing is possible even on rough paper with low surface smoothness.

(2) There is no fading, bleeding, or scumming during printing.

(3) The blocking resistance of the thermal transfer recording medium is improved.

〔Example〕

Examples of the present invention will be described below, but the present invention is not limited thereto. Note that "parts" used below indicate "parts by weight."

The following coating composition was coated onto a polyethylene terephthalate film of 3.5 tIm using a wire bar so as to have a dry film thickness of 3.0 μm to form the Tm of the present invention.

Paraffin wax emulsion (a emulsion made by emulsifying paraffin wax at a temperature of 70°C in water with polyethylene gelyfur monostearyl ether, solid content 30%)
)・・・・・・・・・・・・・・・・・・・・・
85, Z two-handed shin-vinyl acetate copolymer emulsion (Adfu) AD-37P295 Manufactured by Toyo Morton Co., Ltd. Solid content: 10%)
・・・・・・・・・・・・・・・11.25 parts fluorine surfactant (FT-248 manufactured by Bayer AG) 2% aqueous solution...
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・2.5 parts Next, apply an ink composition as shown in Table 1 on Tm so that the dry film thickness is 1.2 pm. Eight kinds of thermal transfer recording medium samples (1-Vl) of the present invention were obtained.

The following margin thermal transfer recording medium sample was printed on a thermal printer (2,1d
at serial head, printing pressure 600g/head.

D (printing) was performed on plain paper and rough paper using a prototype machine with a platen rubber hardness of 50'. Note that commercially available flat paper (Peck smoothness: 9 seconds) was used as the plain paper, and pound paper (Peck smoothness: 10 seconds) was used as the rough paper. Clear prints with no fading, bleeding, or scumming were obtained on all papers. Furthermore, these thermal transfer recording media did not cause blocking even after long-term storage.

Ratio (Example 1) When printing was performed in the same manner as in the example using heat-sensitive transfer recording medium samples obtained by applying the ink layer in the example at 3.0 Am, all the samples showed almost no printing. L rj was distorted and significant printing leakage occurred.

Ratio (Example 2) In Example 2, a thermal transfer recording medium sample obtained by dispersing an ink composition dissolved and dispersed in a mixed solvent of methyl ethyl ketone/toluene instead of water at 1.2 am as in Example was used. When printing was carried out in the same manner as in Examples, significant whiskers occurred at the edge portions of the prints.Also, these thermal transfer recording media exhibited significant blocking during storage.

Comparative Example 3 When the ink composition shown in Table 1 was applied on the lower layer formed by heating and applying toluene instead of water in the lower layer coating composition in the example, a remarkable repelling phenomenon was observed. Therefore, a satisfactory thermal transfer recording medium could not be obtained.

Claims (2)

[Claims] (1) A thermal transfer recording medium having, on a support, at least a layer containing an aqueous emulsion of a thermofusible substance, and at least one ink layer containing an aqueous emulsion of a thermoplastic resin thereon, the ink layer The film thickness is 2μ
A heat-sensitive transfer recording medium characterized in that it has a diameter of less than m. (2) The heat-sensitive transfer recording medium according to claim 1, wherein the layer containing the aqueous emulsion of the heat-melting substance is thicker than the ink layer.