JPH0441919B2 - - Google Patents

Description

[Detailed description of the invention]

(A) Industrial Application Field The present invention relates to a thermal transfer recording sheet capable of gradation recording in a thermal transfer system using a thermal head. (B) Conventional technology Traditionally, thermal transfer systems include a thermal sublimation transfer method, in which an ink layer containing a heat sublimable dye is formed on a support, and the dye is sublimated onto the image receiving paper side for recording by heating; Forming a heat-melting ink layer containing colored dyes and pigments on the body (hereinafter referred to as donor sheet)
A heat-fusion transfer method is known in which recording is performed by melt-transferring to the image-receiving paper side by heating. Since the thermal sublimation transfer method uses dye as a gas to perform transfer recording, the gradation of the image is good and it is seen as a promising full-color recording method, and inventions have been made to improve the dye-dyeability of the image-receiving paper for this system. ing. (Unexamined Japanese Patent Publication No. 57-
91296, JP 57-107885, JP 57-137191,
(JP-A-59-59495, JP-A-59-64393) However, the thermal sublimation transfer method requires a long heating time due to the high sublimation temperature of the dye, and has the disadvantage that the recording speed is slow. It is also possible to use a dye with a low sublimation temperature, but the re-sublimation of the dye results in poor image storage stability, and furthermore, because it is a dye, the image's light resistance is also poor. For these reasons, various methods of producing gradation using a thermal melt transfer method, which has a high recording speed and good image storage stability, have recently been studied. For example, in JP-A-57-56295, a heat-fusible ink layer (A) is provided on a support, and on the ink layer (A), dots are arranged at intervals from each other. ) is provided with a large number of spot-shaped heat-fusible ink layers (B) with a lower melting point than the ink layer (B), and the amount of ink transferred is changed by heating to produce intermediate tones. In addition, Japanese Patent Application Laid-Open No. 59-64391 discloses that on a support,
An image-forming substance formed by coating a layer containing an image-forming substance capable of forming an image by heating, and an image-receiving layer capable of receiving the image-forming substance and transferring it to a transfer medium by heating. The amount of thermal transfer to the image receiving paper side is controlled. (C) Problems to be solved by the invention The patent publications cited in the prior art mentioned above have various problems. For example, JP-A-57-56295 and JP-A-59-64391 both attempt to produce gradation by devising the layer structure of the ink applied to the support. That is,
The disadvantage is that the donor sheet must be completed by two coatings, and the manufacturing cost is also high. In addition, conventional single-layer donor sheets contain colored dyes and pigments,
A hot-melt ink containing a binder, waxes, and other additives is applied to a support by the gravure method or flexo method. This is probably because the coating layer has a high packing density and has good conductivity for the heat given by the thermal head, and the ink layer that corresponds to the shape of the thermal head is almost completely dissolved. When thermal transfer printing is performed on plain paper or coated paper, even if the printing machine has 16 or so gradations, no density gradation can be obtained, and the image is very high-contrast.
OFF2 value recording. Therefore, in this industry, donor sheets with different transfer densities are used to perform multiple overprinting to create density gradations, and at the same time, area gradation methods are also used to control the number of halftone dots in the printed matrix. I am trying to obtain a high-gradation image using a complicated method. This has the disadvantage that the manufacturing cost of the donor sheet is high and the printing speed is also slow. The present inventors conducted research aimed at solving these drawbacks and obtaining a thermal transfer recording sheet capable of gradation recording. (D) Means for Solving the Problems The present inventors conducted intensive research to solve these drawbacks, and as a result, they were able to provide a gradation thermal transfer recording sheet. That is, in a thermal transfer recording sheet in which a heat-melt ink layer containing colored dyes and pigments, binders, and waxes as main components is coated on one side of a support, the heat-melt ink contains gallic acid or its derivatives and acetylene. By containing glycol, a thermal transfer recording sheet capable of gradation recording could be provided. In addition, the gradation thermal transfer recording sheet of the present invention has good dispersibility in other components of dyes and pigments when producing hot-melt ink due to the acetylene glycol content, and also has good adhesion to the support. It has the characteristics of being excellent. Specifically, the gallic acid or its derivatives include gallic acid, methyl gallate, ethyl gallate, propyl gallate, isoamyl gallate, octyl gallate, lauryl gallate, stearyl gallate, trimethoxy gallate. , trimethoxy gallic acid methyl ester, gallic acid 3-methyl ether, gallic acid 4-methyl ether, gallic acid 3,4-dimethyl ether, and gallic acid 3,5-dimethyl ether. More preferably, the gallic acid derivative consists of at least one gallic acid alkyl ester selected from methyl gallate, ethyl gallate, propyl gallate, isoamyl gallate, octyl gallate, lauryl gallate, and stearyl gallate. It is. The heat-melt ink of the present invention contains gallic acid or a derivative thereof in an amount of 5 to 50% per total weight of the heat-melt ink as a component of colored dyes and pigments, binders, and waxes.
By containing it in a weight percent, gradation recording can be obtained. Preferably it is 10 to 30 weight percent. Also, acetylene glycol is 2, 4, 7, 9
-Tetramethyl-5-decyne-4,7-diol, its ethylene oxide adduct, and at least one selected from 3,6-dimethyl-4-octyne-3,6-diol. acetylene glycol is 0.1 to 20 weight percent based on the dry solids content of the hot melt ink;
Preferably it is 0.5 to 10 weight percent. The gradation thermal transfer recording sheet of the present invention can produce images with high density gradation simply by coating a support in a single layer. Rather than coating with a single color,
An image with color gradation can also be obtained by forming a thermal transfer recording sheet in which a heat-melting ink consisting of dyes and pigments of at least yellow, magenta, and cyan colors is partially coated on a support. Furthermore, because the dye and pigment in the heat-melt ink have good dispersibility and the ink has excellent adhesion to the support, a gradation thermal transfer recording sheet coated with a more homogeneous heat-melt ink layer is manufactured. be able to. The reason why the thermal transfer recording sheet of the present invention has density gradation is not very clear, but when the only component that provides the transfer effect of heat-melting ink in a normal thermal transfer recording sheet is wax, the ink is applied from the thermal head. While complete transfer to the image receiving paper occurs at a certain level of energy, the mixture of gallic acid or its derivatives of the present invention has a high melting point and suppresses the amount of transfer at low energy, gradually increasing in proportion to the increase in energy. It is thought that density gradation appears as the amount of transfer increases. Furthermore, when the components of the present invention are mixed, when the heat-melting ink layer on the thermal transfer recording sheet is enlarged, the ink is arranged in the form of particles on the support, and the particles change depending on the energy of the thermal head. It is thought that there is a tendency for density gradation to appear even more easily as the ink is independently transferred to the image receiving paper surface. The inclusion of acetylene glycol in the present invention provides a synergistic effect on the above-mentioned advantages due to its characteristics of uniform dispersion of dyes and pigments and excellent adhesion to the support. Furthermore, the types, amounts, and melting points of binders, waxes, dyes and pigments, which are the main components of the heat-melting ink, are also thought to have a subtle influence. For example, waxes have a melting point of 50℃~
Waxes at 200℃, preferably 60℃ to 150℃ are good, and if the melting point is lower than 50℃, the morphology in the ink layer, even if it is particulate, is too sensitive during thermal transfer. Therefore, it is difficult to obtain density gradation.
On the other hand, if the melting point is higher than 200°C, high energy is required for the thermal head and the amount of thermal transfer is reduced, making it impractical. Typical examples of such waxes are listed below, but the waxes are not limited thereto. Examples of waxes include plant-based waxes such as rice wax, Japanese wax, Candelilla wax, and carnauba wax; animal-based waxes such as lanolin, beeswax, and Seratus wax; and mineral-based waxes such as Montan wax. Synthetic waxes such as paraffin wax, microcrystalline wax, oxidized paraffin wax, chlorinated paraffin wax, ricinoleic acid amide, lauric acid amide, erucic acid amide, palmitic acid amide, oleic acid amide, 12-hydroxy Metallic soaps such as stearic acid, distearyl ketone, and ethylene bisstearamide include sodium stearate, sodium palmitate, potassium laurate, potassium myristate, calcium stearate, zinc stearate, aluminum stearate, magnesium stearate, and stearin. acid lead, dibasic barium stearate, etc.
Examples of higher fatty acids include palmitic acid and stearic acid; examples of higher alcohols include palmityl alcohol, stearyl alcohol, and ceryl alcohol; and examples of synthetic polyalcohols include polyethylene glycol and polypropylene glycol. Next, as dyes and pigments, any of water-soluble dyes, oil-soluble dyes and pigments, disperse dyes, and solvent-insoluble organic pigments can be used, and they are not directly related to the quality of gradation. Each of the above types of dyes and pigments can be used depending on the coating method. In particular, water-soluble dyes are preferably used for water-based coating and solvent coating. Further, for those that dissolve in organic solvents, solvent coating is preferable, and in the case of hot melt coating, either dissolution or dispersion may be used. It is better to make the dye and pigment into fine particles with a particle size of about 1 μm or less, so that the transferred image does not have roughness. Although there are sublimation dyes, the dyes of the present invention cannot fully exhibit their sublimation function. However, as long as it is used as a coloring material, it does not impede the present invention and may be used without any problem. Specific examples of dyes and pigments are given below,
It is not limited to these, and two or more types may be used in combination. Water-soluble dyes include nitroso dyes, azo dyes (mono, bis, tris, and tetrakisazo dyes), stilbene azo dyes, ketoimine (diphenylmethane) dyes, triphenylmethane dyes, xanthene dyes, acridine dyes, quinoline dyes, methine dyes, Examples include polymethine dyes, thiazole dyes, indamine dyes, azine dyes, thiazine dyes, oxyketone dyes, anthraquinone dyes, and phthalocyanine dyes. To give more specific examples, the nitroso dye is Mordant Green 4 (CI10005, hereinafter CI No. is shown in brackets), and the azo dye is Direct Red 28.
(22120), Direct Orange 71 (40205) as a stilbene azo dye, Basic Yellow 2 (41000) as a ketoimine dye, Basic Blue 1 (42025) as a triphenylmethane dye, Acid Red 52 (45100) as a xanthene dye,
Basic Orange 23 is an acridine dye.
(46075), quinoline dye Acid Yellow 2 (47010), methine dye Direct Yellow 59 (49000), azine dye Acid Blue 59 (50315), oxazine dye Mordant Blue 10 (51030), thiazine dye Basic Blue 9 (52015) is an anthraquinone dye, Acid Blue 45 (63010) is an anthraquinone dye, and Direct Blue 86 (74180) is a phthalocyanine dye. Examples of oil-soluble dyes include azo dyes, azo metal complex dyes, anthraquinone dyes, and phthalocyanine dyes. To give more specific examples, examples of azo dyes include Solvent Yellow 2 (IC11020, hereinafter CI No. in brackets), Solvent Orange 1 (11920), and Solvent Ret.
24 (26105), Solvent Brown 3 (11360), etc.Azo metal complex dyes include Solvent Yellow 19 (13900A) and Solvent Orange 5.
(18745A), Solvent Red 8 (12715), Solvent Brown 37, Solvent Black 123 (12195)
Examples of anthraquinone dyes include Solvent Violet 13 (60725) and Solvent Blue 11.
(61525), Solvent Green 3 (61565), etc.
Solvent Blue 25 is a phthalocyanine dye.
(74350) etc. Examples of disperse dyes include aminoazo or aminoanthraquinone dyes, nitroarylamine dyes, and the like. To give a more specific example, the aminoazo dye is Days Purse Yellow 3.
(CI11855, below the box indicates CI No.), Dayspurs Orange 3 (11005), Dayspurs Red 1 (11110), Dayspurs Violet 24
(11200), Dayspurs Blue 44, etc. Aminoanthraquinone dyes include Days Perz Orange 11 (60700) and Days Pers Red 4.
(60755), Dayspurs Violet 1 (61100),
Examples include Dayspurs Blue 3 (61505). Nitroarylamine dyes include Days Purse Yellow 1 (10345) and 42 (10338). Pigments include azo pigments (monoazo, bisazo, condensed azo pigments), dye lake pigments (acid dye lake, basic dye lake, mordant dye lake pigments), nitro pigments, nitroso pigments, phthalocyanine pigments, and high-grade pigments (vat dyes). pigments, metal complex salt pigments, perylene pigments, isoindolinone pigments, and quinacridone pigments). To give more specific examples, examples of azo pigments include Hansa Yellow G (CI11680, CI No. is shown below in brackets), Hansa Yellow R (12710), Pyrazolone Red B (21120), Permanent Red R (12085), and Lake Red C. (15585), Brilliant Carmine 6B
(15850), Permanent Carmine FB (12490) (monoazo pigments), Benzidine Yellow G (21090),
Examples include Benzidine Yellow GR (21100), Permanent Yellow NCR (20040) (bisazo pigments), Chromophthal Yellow, and Chromophthal Red (condensed azo pigments). Dyeing lake pigments include quinoline yellow lake (47005), eosin lake (45380), alkali blue lake (42750A,
42770A) (Acidic dye lake pigment), Rhodamine Lake B (45170), Methyl Violet Lake (42535), Victoria Blue Lake (44045), Malachite Green Lake (42000) (Basic dye lake pigment), Alizarin Lake ( 58000) (mordant dye lake pigment). Nitro pigments include Naphthol Yellow S (10316), nitroso pigments include Pigmen and Green B (10006) and Naphthol Green B (10020), and phthalocyanine pigments include metal-free Phthalocyanine Blue (74100), Phthalocyanine Blue (74160), and Phthalocyanine Green ( 74260). As a high-grade pigment,
Anthrapyrimidine Yellow (68420), Indanthrene Brilliant Orange GK (59305), Indanthrene Blue RS (69800), Thioindigolet B (73300) (vat dye pigments), Nickel Azo Yellow (12775) ( Metal complex salt pigment), perylene red (71140), perylene scarlet (71137) (perylene pigment), isoindolinone yellow (isoindolinone pigment), quinacridone red Y
(46500) and Quinacridone Magenta (73915). Carbon black (C.
I.77265). Either a water-soluble binder or a water-insoluble binder can be used as the binder, and a water-soluble binder is used for an aqueous/non-aqueous system of a mixed medium consisting of a water-soluble medium and a non-aqueous medium by solvent coating. . Water-insoluble binders are used for solvent coating and hot melt coating. Typical examples of such binders are illustrated below, but the binder is not limited to these, and two or more types may be used in combination. Examples of the binder include polyvinyl alcohol, methylcellulose, gelatin hydroxyethylcellulose, carboxymethylcellulose, gum arabic, starch and its derivatives, casein, polyvinylpyrrolidone, butyral resin,
Ethylene ethyl acrylate, sterene-butadiene copolymer, vinyl acetate resin, vinyl acetate-based copolymer, acrylic resin, methyl methacrylic resin, styrene-acrylonitrile resin, ethylene-vinyl acetate copolymer, polyester resin, petroleum resin, etc. be able to. The amount of dye/pigment used based on the main component of the heat-melting ink is 0.5 to 40% by weight, preferably 1% by weight.
-25% weight percent, waxes 10-70 weight percent, preferably 20-60 weight percent, binder 5-60 weight percent, preferably 10-50 weight percent. In the present invention, as described above, gallic acid or its derivatives, acetylene glycol, colored dyes and pigments, binders, and waxes are the main components, but when coating or printing on the support, other additives such as surfactants are added. Agents, dispersants, antistatic agents, antioxidants, ultraviolet inhibitors, etc. may be added. As a support, thin paper such as capacitor paper, typewriter paper, tracing paper, synthetic paper,
Cellophane paper, as well as synthetic resin films such as polyester film, polyimide film, polyethylene film, polycarbonate film, polystyrene film, and Teflon film, are used as they are or after heat-resistant treatment to prevent them from sticking to a hot head. Coating machines include hot melt coater, air knife coater, roll coater, blade coater,
Coating is carried out using a known coater such as a bar coater, and a known printing machine using a flexo method, a gravure method, etc. may also be used. In order to obtain a full-color image, at least yellow, magenta, and cyan color inks are partially printed on the same support in a line-sequential, area-sequential, or dot-sequential manner. Note that solvent coating can be carried out using general solvents, such as methanol, ethanol, isopropyl alcohol, toluene, methyl ethyl ketone, acetone, ethyl acetate, etc., as appropriate. (E) Effect The gradation thermal transfer recording sheet of the present invention contains gallic acid or a derivative thereof and acetylene glycol in a heat-melting ink containing colored dyes and pigments, a binder, and waxes as main components on one side of a support. This allows recording with a high degree of gradation. With conventional thermal transfer recording sheets, when an image is formed using a thermal head, when printing starts from a low energy state, there is little difference in transfer density from the energy range where transfer occurs to high energy, and the transfer density remains constant. Unable to obtain gradation. On the other hand, since the thermal transfer recording sheet of the present invention contains gallic acid or its derivative and acetylene glycol in the ink composition, it has excellent dispersibility of the dye and pigment of the ink and adhesion of the ink to the support, and can be used in a low energy range. It exhibits smooth transfer density up to high energies and can provide gradation. This is a wax that has high transfer efficiency and gallic acid or its derivatives that have a high melting point to control the transfer properties and exhibits transfer with gradation. It works more efficiently. Furthermore, acetylene glycol works effectively when it is contained in an amount of 0.1 to 20% by weight. (F) Examples Hereinafter, the present invention will be specifically explained with reference to Examples. Note that "parts" in Examples and Comparative Examples indicate parts by weight of solid content. Example 1 In producing a 1-1 gradation thermal transfer recording sheet (donor sheet), the composition of the heat-melting ink was as follows, and the dry coating method was applied to a 9 μPET film that had been heat-resistant treated using a Mayer bar. 4 g/m ² was solvent coated. SOT Blue G (Hodogaya Chemical, melting point 74-75℃)
10 parts by weight 150% Paraffin wax 40 parts by weight Polyvinyl alcohol 20 parts by weight Lauryl gallate (melting point 96°C) 30 parts by weight 2,4,7,9-tetramethyl-5-decyne-
4,7-diol 3 parts by weight The heat-melting ink is prepared using a ball mill.
It was prepared as a 20% ethanol dispersion. The ink side of the prepared donor sheet was placed on plain paper (receiving paper for thermal transfer paper, manufactured by Mitsubishi Paper Mills, trade name TTR-PW), and the voltage was applied from the back side of the donor sheet using a facsimile tester manufactured by Matsushita Electronic Components at 16.0V. Heat printing is performed by changing the pulse width from 0.2 ms to 3.0 ms every 0.2 ms, and the density of the transferred image is measured using an optical densitometer (Macbeth).
RD514 type). The results are shown in Table 1. Also, the acetylene glycol of the present invention, namely 2,4,7,9-tetramethyl-5-decyne-
Due to the addition of 4,7-diol, the donor sheet was repeatedly folded and the degree of peeling of the ink layer was observed for adhesion to the PET film, but no peeling occurred. Experiments 1-2, 1-3, 1-4, and 1-5, as well as 1-1 to 1-3 as comparative examples, were conducted in the same manner as 1-1, and the results are listed in Table 1. In Table 1, regarding the adhesion between the PET film and the hot-melt ink layer, those in which peeling of the ink layer does not occur are marked as ○, and those in which peeling occurs (Comparative Examples 1-1 and 1)
-2) and the one in which the ink layer became sticky and caused an adhesive effect (Comparative Example 1-3) were marked as x. As is clear from Table 1, Examples 1-1 to 1
-5 shows that the density changes with gradation and the adhesion between the PET film and the ink layer is good, whereas in the comparative example, 1-1 shows that the transfer density changes from the low pulse width region. It had no high gradation. In Comparative Example 1-2, there was no adhesion between the PET film and the ink layer, resulting in peeling. but,
It was equipped with gradation. In Comparative Example 1-3
The adhesion between the PET film and the ink layer was so excessive that the ink layer became sticky and unusable.

【table】

[Table] Example 2 To prepare a gradation thermal transfer recording sheet (donor sheet), the following hot melt ink was prepared and coated on a heat-resistant 9μPET film at a coating rate of 3.5 g/m. ² , hot melt coating was applied. Carbon Black 10 parts by weight Paraffin Wax (Product name: SP- manufactured by Nippon Seiro Co., Ltd.)
0145) 53 parts by weight ethylene-vinyl acetate resin 6 parts by weight petroleum resin (manufactured by Arakawa Chemical, trade name Alcon M)
6 parts by weight Ethyl gallate (melting point 150-153°C) 25 parts by weight 3,6-dimethyl-4-octyne 3,6-diol 5 parts by weight The prepared donor sheet was printed in the same manner as in Example 1, The results are shown in Table 2. Comparative Example 2 A donor sheet was prepared using the same method as in Example 2 except that ethyl gallate was removed from the hot-melt ink and the amount of paraffin wax was 78 parts by weight. Printing was carried out in the same manner as in Example 2, and the results are shown in Table 2. As is clear from Table 2, Example 2 shows a gradation density change and good adhesion between the PET film and the ink layer, whereas Comparative Example 2 shows that the PET film and the ink layer have good adhesion. Although the adhesion with the layer was good, high density was exhibited from the low pulse region and no gradation was obtained.

【table】

[Table] (G) Effects of the Invention The present invention provides heat-melting ink containing gallic acetic acid and/or
By containing or a derivative thereof and acetylene glycol, the ink has excellent adhesion to the support and extremely high density gradation can be obtained.
By partially coating the four colors of black and black, a color image with high color reproducibility can be obtained, and an excellent gradation thermal transfer recording sheet of industrial significance can be provided.

Claims (1)

[Claims] 1 Colored dyes and pigments, binders,
A gradation thermal transfer recording sheet comprising a heat-melt ink layer coated with waxes as a main component, characterized in that the heat-melt ink contains gallic acid or a derivative thereof and acetylene glycol. sheet. 2. The gallic acid or its derivatives are gallic acid, methyl gallate, ethyl gallate, propyl gallate, isoamyl gallate, octyl gallate, lauryl gallate, stearyl gallate, trimethoxy gallic acid, trimethoxy gallic acid methyl ester, gallic acid. acid 3-methyl ether, gallic acid 4
The gradation thermal transfer recording sheet according to claim 1, which is at least one selected from -methyl ether, gallic acid 3,4-dimethyl ether, and gallic acid 3,5-dimethyl ether. 3. The gradation thermal transfer recording sheet according to claim 1, wherein the gallic acid or its derivative is present in an amount of 5 to 50 weight percent based on the total weight of the heat-melting ink. 4 The acetylene glycol is 2,4,7,9
-Tetramethyl-5-decyne-4,7-diol and its ethylene oxide adduct, and at least one selected from 3,6-dimethyl-4-octyne-3,6-diol, according to claim 1. gradation thermal transfer recording sheet. 5. The gradation thermal transfer recording sheet according to claim 1, wherein the acetylene glycol is present in an amount of 0.1 to 20 weight percent based on the dry solid content of the heat-melting ink.