JPH02107479A - Thermal transfer sheet - Google Patents

Abstract

PURPOSE:To obtain a thermal transfer sheet for cyan as one of three primary colors which has appropriate sublimation or transpiration properties, is excellent in various kinds of fastness and has favorable suitability for ink preparation by providing a coloring material layer comprising a specified coloring matter on one side of a base film. CONSTITUTION:A coloring material layer comprising a coloring matter of formula (I) is provided on one side of a base film. In the formula, R is an alkyl, alkoxyalkyl, alkoxyalkoxyalkyl, hydroxyalkyl, cycloalkyl, alkenyl, aralkyl or aryl. The coloring matter of formula (I) can be obtained by, for example, bringing 1,8-dihydroxy-4,5-dinitroanthraquinone into reaction with a corresponding amine. The coloring matter is used to prepare an ink, which is applied to one side of the base film, e.g., a film of cellophane or a polyimide resin, followed by drying to provide the coloring material layer, thereby producing a thermal transfer sheet. The ink is prepared by dissolving or dispersing the coloring matter, a binder (e.g., dextrin or casein), an antitack agent, an antioxidant, a UV absorber, etc., in a solvent such as water and ethanol by a ball mill or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a thermal transfer sheet containing a cyan dye that is excellent in sublimation or evaporation properties and in various fastness properties.

<Prior Art> Conventionally, there has been a demand for a technology for obtaining color hard copies from televisions, CRT color displays, color facsimiles, magnetic cameras, etc., and methods using electrophotography, inkjet, thermal transfer, etc. are being considered.

The thermal transfer method is a method in which a transfer sheet with an ink layer containing a sublimable or evaporable dye formed on a base film is heated by a thermal head to sublimate or evaporate the dye, and transfer recording is performed onto a recording medium. By changing the energy given to the thermal head, it is possible to control the amount of dye sublimation or evaporation, which facilitates gradation recording and provides high-definition color images. It is considered advantageous.

In the thermal transfer method, the dye used in the transfer sheet is very important as it has a great effect on the transfer recording speed, recording image quality, storage stability, etc., and is required to satisfy the following conditions.

(1) Good sublimation or evaporation properties under the operating conditions of the thermal head.

(2) Do not thermally decompose under the operating conditions of the thermal head.

(3) It has a favorable hue in terms of color reproduction.

(4) Stable against heat, light, moisture, chemicals, etc.

(5) Excellent suitability for ink formation.

Currently, various dyes, mainly disperse dyes, are used as dyes for thermal transfer (for example, Japanese Patent Application Laid-Open No. 62199655
However, none of the above-mentioned requirements are satisfied, and there are problems with sublimation or evaporation properties, recording density, hue, various fastness properties, suitability for ink formation, etc., and especially with cyan color pigments. has various drawbacks, and at present no satisfactory solution has yet been found.

<Problems to be Solved by the Invention> The present inventors have worked diligently to find a cyan thermal transfer sheet for the three primary colors that has appropriate sublimation or transpiration properties, is excellent in various fastness properties, and has good suitability for ink formation. As a result of investigation, the inventors found that the purpose can be well achieved by using a specific cyan dye, and have completed the present invention.

Means for Solving the Problems> The present invention provides a method in which the following general formula (1) is formed on one surface of the base film.
) % formula % (wherein R is an alkyl group, an alkoxyalkyl group, an alkoxyalkoxyalkyl group, a hydroxyalkyl group,
Represents a cycloalkyl group, alkenyl group, aralkyl group or aryl group. ) The present invention provides a thermal transfer sheet characterized by having a coloring material layer containing a dye represented by:

In the general formula (1), specific examples of the alkyl group represented by R include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, 5e
c-butyl, n-amyl, isoamyl, n-hexyl, n-hebutyl, n-octyl, 2-ethylhexyl, n
-nonyl, n-decyl, etc.

Specific examples of the alkoxyalkyl group include methoxypropyl, ethoxypropyl, propoxypropyl, butoxypropyl, and 2-ethylhexyloxypropyl. Specific examples of the alkoxyalkoxyalkyl group include methoxyethoxyethyl, ethoxyethoxyethyl, n-butoxyethoxyethyl, n-propoxyethoxyethyl, and 1-propoxyethoxyethyl.

Further, specific examples of the hydroxyalkyl group include hydroxydityl, hydroxypropylhydroxybutyl, and the like. Further, specific examples of the cycloalkyl group include cyclopentyl and cyclohexyl.

Furthermore, specific examples of the alkenyl group include allyl group and crotyl group. Specific examples of the aralkyl group include benzyl, phenethyl, and phenylpropyl. A specific example of the allyl group is a phenyl group, which further includes an alkyl group, a hydroxyalkyl group,
It may be substituted with at least one alkoxy group or halogen atom.

The dye represented by the general formula (1) can be obtained by a known method, for example, by reacting 1,8-dihydroxy-4,5-dinitroanthraquinone with a corresponding amine.

In the present invention, a thermal transfer sheet is manufactured by forming a dye represented by the above general formula into an ink, applying it to one side of a base film, and drying it to form a coloring material layer.

Here, the base film is generally a ribbon-like or film-like material such as capacitor paper, cellophane, polyimide resin, polyester resin, polyethersulfone resin, or these resins treated to improve heat resistance and/or smoothness. The following are exemplified.

Ink formation is generally carried out using a dye represented by the general formula (I), a binder, and, if necessary, an anti-tackifier, an antioxidant,
Dissolve or disperse (atomize) ultraviolet absorbers, etc. in a solvent using a ball mill or paint conditioner, etc.
It is done as follows.

As a binder, natural resins such as dammar, gum arabic tragacanth, dextrin or casein or modified resins thereof, cellulosic resins such as methylcellulose, ethylcellulose, hydroxyethylcellulose, ethylhydroxycellulose, ethylhydroxyethylcellulose or nitrocellulose, acrylic acid-based resins, etc. Examples include vinyl resins such as resin, polyvinyl alcohol, and polyvinyl acetate, and one or a mixture of two or more of these may be used.

Dissolve or disperse (atomize) pigments, binders, etc.
Examples of solvents include water, ethanol, propatool,
Alcohols such as butanol, ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, aromatic hydrocarbons such as toluene, xylene, and monochlorobenzene, chlorinated solvents such as dichloroethane, trichlorethylene, and perchlorethylene, ethyl acetate, Examples include acetate esters such as butyl acetate and ethoxyethyl acetate, and one or a mixture of two or more of these may be used.

The dye ink thus obtained is coated with a bar coater,
Roll coater, knife coater, screen printing machine,
A thermal transfer sheet is manufactured by applying it onto a base film using a gravure printer or the like and drying it.

The thermal transfer sheet of the present invention thus produced is a cyan thermal transfer sheet for the three primary colors, which has appropriate sublimation or evaporation properties, excellent fastness properties, and good suitability for ink formation.

Any known method for printing using a thermal transfer sheet can be used, and a clear image can be obtained on the print paper.

Printing paper can be paper coated with polyester resin or polyamide resin, synthetic paper such as polypropylene, polyvinyl chloride, or polyester, or synthetic paper that has been treated to improve heat resistance, etc., as necessary. Materials coated with polyester resin, polyamide resin, etc., which have a strong affinity for dyes, are used.

<Effects of the Invention> The cyan dye represented by the general formula (1) used in the present invention has good suitability for forming into an ink, and the thermal transfer sheet manufactured using the ink has appropriate sublimation or evaporation properties. It has a high recording density on printing paper, and the recorded image has excellent light resistance and storage stability, and is used as a cyan thermal transfer sheet for the three primary colors.

<Examples> Hereinafter, the present invention will be explained in detail by giving examples. In the examples, parts represent parts by weight.

Example 1 (1) Synthesis of dye 1. A mixture of 10 parts of 8-dihydroxy-4,5-dinitroanthraquinone and 30 parts of aniline is stirred at 145°C for 1 hour.

Thereafter, the mixture was cooled to 60°C, 100 parts of methanol was added dropwise, and the mixture was stirred at 20°C for 1 hour.

The precipitated crystals were separated by filtration, washed with methanol and then with water,
After drying, a dye of the following formula was obtained.

OHOoH λ ll1ax (mouth MF> 63
2 nm (2) Preparation method of ink Pigment obtained in the above (1) 2 parts Ethyl cellulose 6 parts Toluene 44 parts Methyl ethyl ketone 44 parts Total 96 parts Thoroughly knead the mixture of the above composition with a paint conditioner using glass beads. The ink was prepared by:

(3) Method for creating thermal transfer sheets Use a percoater to apply the ink prepared in (2) to a heat-resistant treated polyester film with a thickness of 6 μm to a wet film thickness of 12 μm, and dry in a hot air dryer at 80°C. It was dried to obtain a thermal transfer sheet. The inking properties of the pigment in the coating layer were good without any problem of particle precipitation.

(4) How to make print paper Saturated polyester resin (manufactured by Toyobo Co., Ltd., Pylon 200)
A 20% by weight toluene/methyl ethyl ketone solution was coated on synthetic paper (YUPO" 150, manufactured by Tamago Yuka Co., Ltd.) using a bar coater to a wet film thickness of 12 μm, and dried in a hot air dryer at 80° C. for 30 minutes.

(5) Thermal transfer recording method The ink-coated surface of the thermal transfer sheet is placed on the polyester-coated surface of the printing paper, and thermal transfer recording is performed using a thermal head having a 200Ω heating resistor at a density of 4 dots/ff1fl. , recording density 1 with clear cyan color
647 records were obtained.

Recording conditions Applied voltage: 8. Ov Note that the recording density was measured using a densitometer model RD-914 manufactured by Macbeth, USA.

When the light resistance test of the obtained record was carried out using a carbon arc fade meter (manufactured by Shimadzu Corporation), it was found that 40
Almost no discoloration or fading was observed after irradiation for several hours. Furthermore, the recorded image was stable against heat and humidity (60° C., 80%).

Examples 2 to 32 The dyes shown in Table 1 were obtained in the same manner as in Example 1, thermal transfer sheets were prepared using the dyes, and a transfer test was conducted to obtain clear cyan-colored records with high recording density. The records obtained had excellent light resistance, moisture resistance, and good storage stability.

Note that the evaluation of light resistance and recording stability in Table 1 below was expressed based on the following criteria.

■ Light resistance After irradiating the record with a fade meter for 40 hours, no change was marked ◎, slight discoloration and fading was marked ○, discoloration and fading was △, and marked discoloration and fading was marked X.

■ Stability (recording) After leaving the record in an atmosphere of 60℃ and 80% humidity for a long time, the white paper does not become colored even if the surface is rubbed with white paper.◎
A case where the white paper was slightly colored was indicated as ○, a case where the white paper was colored was indicated as Δ, and a case where the white paper was markedly colored was indicated as ×.

Table HOOH Comparative Example 11 The same procedure as in Example was carried out except that the following A and B were used as dyes, and the results shown in Table 2 were obtained.

table The dye A used in the comparative example was No. 15790 The cyan dye ( (formula below) In addition, the dye B used in the comparative example was The cyan dye described in the publication ( (formula below)

Claims (1)

[Claims] (1) The following general formula (I) is applied to one side of the base film.
▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, R is an alkyl group, an alkoxyalkyl group, an alkoxyalkoxyalkyl group, a hydroxyalkyl group,
Represents a cycloalkyl group, alkenyl group, aralkyl group or allyl group. ) A thermal transfer sheet characterized by having a coloring material layer containing a dye represented by: