JPH02188296A - Transfer sheet for thermosensitive transfer recording - Google Patents

Abstract

PURPOSE:To read the data optically with light of long wavelength by providing a layer containing a transfer pigment with a large absorbing range from a specified wavelength to a long wavelength on a support. CONSTITUTION:A layer containing a pigment with a large absorbing range from 725nm to a long wavelength is provided on a support. The pigment with a large absorbing range from 725nm to a long wavelength is, for instance, such a pigment as expressed by formula. In the formula R<1>, R<2> are an alkyl group with 1 to 4 carbons or hydrogen atom which may be substituted; R<3> is an alkyl group, an alkoxy group or an alkylamino group. A transfer sheet is obtained by dispersing the pigment and if necessary, yellow, magenta or cyan in a solvent with a binder or dispersing its microparticles, and applying this ink to the surface of the support and drying it. The preferable amount of the binder used is 0.1 to 50g/1m<2> of the support, and the preferable thickness of an ink layer is 0.1 to 5mum in terms of dry film.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a transfer sheet for thermal transfer recording, and more specifically, the present invention relates to a transfer sheet for thermal transfer recording. The present invention relates to a transfer sheet for thermal transfer recording.

[Background of the Invention] In recent years, in information recording materials such as various 10 cards, development has been carried out to provide color image information as well as character information or signal information such as a bar code to the same recording material. This recording material, on which character information or signal information is recorded, is optically processed using light with a wavelength longer than 750 nm, such as a semiconductor laser or light emitting diode, in order to speed up information judgment, prevent misidentification, and downsize reading devices. It is often read as such.

On the other hand, as a method for obtaining color hard copies, color recording technologies such as inkjet, electrophotography, and thermal transfer are being considered. Among them, thermal transfer is easy to operate and maintain, has a compact device, and is low in cost. It has excellent features such as being able to perform the following tasks and having low running costs.

Thermal transfer methods include a method in which a transfer sheet having a meltable ink layer on a support is heated by a thermal head to melt and transfer the ink onto a transfer sheet, and a method in which a support contains a sublimable dye. There is a sublimation transfer method in which a transfer sheet with an ink layer is heated by a thermal head to transfer the sublimable dye, but the sublimation transfer method changes the thermal energy of the thermal head to change the amount of dye transferred. This makes it possible to control the gradation of the image, which is advantageous for full-color recording.

The thermal transfer recording method, especially the sublimation method, produces yellow,
Color images, character information, etc. are formed by sequentially transferring three color pigments of magenta and cyan, but the pigment used in these conventional transfer methods is 725 nm.
Since dyes do not have sufficient absorption as described above, it has not been possible to optically read formed character information and the like using light with a wavelength longer than 750 ns.

[Object of the Invention] An object of the present invention is to solve the problems of the above-mentioned prior art. That is, an object of the present invention is to provide a transfer sheet for thermal transfer recording that can obtain image information or character information that can be optically read with light having a wavelength longer than 750 nm.

[Structure of the Invention] The above object of the present invention is achieved by a transfer sheet for thermal transfer recording which contains, on a support, a dye having an absorption maximum at a wavelength longer than 725 nm.

As a dye having an absorption maximum at a wavelength longer than 725ni of the present invention (hereinafter referred to as the dye of the present invention), for example, Color Materials Association Journal 81 (43215-22B (1988)
It is possible to use the dyes described in ``Pigments'' and the dyes listed in the Pigment Handbook (Kodansha Suientific) that have an absorption maximum at a wavelength longer than 725 ni, but there are limitations in terms of light absorption characteristics, transferability, and thermal stability. The following general formula [I], [
A dye represented by [II] or [II[] is preferably used.

General formula [11] In the formula, R' R2 represents an optionally substituted alkyl group having 1 to 4 carbon atoms (for example, a methyl group, an ethyl group, a methoxyethyl group, or a hydrogen atom, and Rj represents an alkyl group,
Represents an alkoxy group or an alkylamino group.

General formula [I[] In the formula, R4R% represents a hydrogen atom, a halogen atom (e.g. fluorine atom, chlorine atom), an optionally substituted alkyl group having 1 to 4 carbon atoms (e.g. methyl group, ethyl group, methoxy ethyl group), alkoxy groups (e.g. methoxy group, methoxyethoxy group), halogen atoms (e.g. fluorine atom,
RIOR11 represents an optionally substituted alkyl group having 1 to 4 carbon atoms (e.g. ethyl group, n-butyl group, hydroxyethyl group, methoxyethyl group) 1, R6 and R7R8 and 1lj9
RIO, 1ljLI R', R11R8 and R10 may be bonded to each other to form a ring.

X represents an electron-withdrawing substituent, particularly preferably a cyano group or -CONHRI2 (R'2 is as defined above).

General formula [m] -NHCORI2 (wherein R'' represents a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms), R6R7R
11R9 is an alkyl group having 1 to 4 carbon atoms (e.g. methyl group, ethyl group, n-butyl group), an alkoxy group (e.g. methoxy group, in the ethoxy formula, X5R4R6R'R'
R9RIG and R11 have the same meanings as defined in general formula [11].

Specific examples of compounds represented by general formulas [I] to [III] are shown below.

(IR-1) (IR-2) (IR-7) (IR-8) (IR-9) (I R-1o) C2)Is 2H5 2H5 2H5 (IR-11) (IR-12) (IR-15) (IR 1B) (IR-13) (IR-14) (IR-17) (IR-18) C3I% 2H5 2H5 2H40H 2H8 2L C.T.

H3 (JR-19) (IR-23) (IR-20) (IR-24) (IR-21) (IR-25) (IR-22) (IR-26) Transfer sheet for thermal transfer recording of the present invention It is preferable to provide on a support, in addition to a layer containing the dye of the present invention, four different ink layers having ink layers sequentially containing yellow, magenta and cyan dyes. Since recording time can be shortened by using three types of ink layers, it is particularly preferable to incorporate the dye of the present invention into a yellow, magenta or cyan ink layer, and form three ink layers. It is a mode.

In the above case, it is preferable to include the dye of the invention in the cyan ink layer, since the dye of the invention usually has some absorption at wavelengths shorter than 700 na+.

In the thermal transfer recording transfer sheet of the present invention, the ink is prepared by dissolving the dye of the present invention and, if necessary, a yellow, magenta or cyan dye in a solvent or dispersing it in the form of fine particles together with a binder. , by applying the ink onto a support and drying it.

As a binder, water-soluble polymers such as cellulose, polyacrylic acid, polyvinyl alcohol, and polyvinylpyrrolidone, and organic solvents such as acrylic resin, methacrylic resin, polystyrene, polycarbonate, polysulfone, polyethersulfone, and ethyl cellulose can be used. There is a melting polymer. For polymers soluble in organic solvents,
It may be used not only by being dissolved in an organic solvent, but also in the form of a latex dispersion.

The amount of binder used is 1rr of support? 0.1g~ per serving
50g is preferred.

Any material can be used as the support as long as it has good dimensional stability and can withstand the heat during recording with a thermal head, but thin paper such as condenser paper, glassine paper, polyethylene terephthalate, polyamide, polycarbonate, etc. A heat-resistant plastic film can be used.

The thickness of the support is preferably 2 to 30 #m, and the support has an undercoat layer for the purpose of improving adhesion with the binder and preventing transfer and dyeing of the dye to the support. It's okay.

Furthermore, a slipping layer may be provided on the back surface of the support (the side opposite to the ink layer) for the purpose of preventing the head from sticking to the support.

The ink layer of the present invention is applied onto a support or printed on the support by a printing method such as a gravure method. The thickness of the ink layer is preferably 0.1 to 5 m in dry film thickness.

Solvents for preparing ink include water, alcohols (e.g. ethanol, propatool), cellosolves (
methyl cellosolve), esters (e.g. ethyl acetate), aromatics (e.g. toluene, xylene, chlorobenzene), ketones (e.g. acetone, methyl ethyl ketone), ethers (e.g. tetrahydrofuran, dioxane), chlorinated solvents (e.g. chloroform , trichlorethylene), etc.

FIG. 1 illustrates an example of a transfer sheet for thermal transfer recording of the present invention, in which 1 is a support, 2 is a layer containing the transferable dye of the present invention, and 3 is a layer containing the transferable cyan dye. 4 is a layer containing a transferable magenta dye, and 5 is a layer containing a transferable yellow dye.

Example 1 Preparation of ink> A mixture having the composition shown below was treated with a paint conditioner to obtain a uniform solution ink containing the transferable dye of the present invention.

Exemplary compound IR-810, polyvinyl butyral resin 15g methyl ethyl ketone 150 ml toluene
150 ml Inks containing the following yellow, magenta, and cyan pigments were obtained in the same manner as above.

Yellow dye> Magenta dye> Cyan dye><Preparation of transfer sheet> The ink containing the above transferable dye of the present invention was applied to a thickness of 1
A wire bar was used on the support 1 made of a 5 pm polyimide film at the position indicated by 2 in FIG. 1, so that the coating amount after drying was l, Og/rr? A layer containing the transferable dye of the present invention was formed by coating and drying to form a layer containing the transferable dye of the present invention.

In the same manner as above, an ink layer containing the yellow, magenta, and cyan dyes is coated on the polyimide film coated with the IR-3 so as to have the structure shown in Figure 1, dried, and then thermally transferred. A recording transfer sheet was obtained.

Transfer Recording> The obtained transfer sheet for thermal transfer recording and the recording medium are stacked so that the ink-applied surface of the transfer sheet for thermal transfer recording faces the recording medium, and IR-recording is performed using a thermal head. 3
The containing layer, the cyan dye-containing layer, the magenta dye-containing layer, and the yellow dye-containing layer were transferred to obtain records in black, cyan, magenta, and yellow. The black record was obtained by transfer recording using four inks overlapping each other, and the cyan, magenta, and yellow records were obtained by transfer recording using the inks of the respective colors.

The reflection density of the obtained black recorded area was measured using infrared light (850 an
+), the concentration was 1.2.

The recording conditions are as follows.

Linear density of main scanning and sub-scanning: 4 tod/m11 Recording power
0.8 w/dot head heating time
10m sec Instead of IR-3, exemplified compounds IR-2, IR-9, IR-12, IR-19, I
Similar results were obtained using R-20 and IR-23.

For comparison, recording was performed in the same manner using a transfer sheet for thermal transfer recording without the IR-3 containing layer, and infrared light (850 nm
) When I measured the reflection density of the black recorded area, the density was 0.
．． 0, and could not be read with infrared light.

Example 2 From the transfer sheet for thermal transfer recording shown in Fig. 1, IR-3
Except for the containing layer, three types of transfer sheets for thermal transfer recording having a cyan dye-containing layer, a magenta dye-containing layer, and a yellow dye-containing layer were prepared.

The first transfer sheet for thermal transfer recording contains IR-19 only in the cyan dye-containing layer, the second transfer sheet for thermal transfer recording contains IR-19 only in the magenta dye-containing layer, and the third transfer sheet contains IR-19 only in the magenta dye-containing layer. In the transfer sheet for thermal transfer recording, IR-19 was contained only in the yellow dye-containing layer.

Examples using each transfer sheet for thermal transfer recording
Recording was performed in the same manner as in 1.

Note that the content of IR-19 is the same as the amount contained in the IR-containing layer of Example-1.

The reflection density of the black recorded portion of the obtained record was measured using infrared light (85
When measured at 0 nm), all three types of sheets had a value of 1.0.

Furthermore, when comparing the recording areas of yellow, magenta, and cyan, it was found that the sheet containing IR-19 in the cyan dye-containing layer produced recordings with high color purity for each color. In the case of using a sheet containing yellow dye in the layer, slight cyan color mixing was observed.

The above-mentioned ink sheet can obtain full-color recording and infrared-readable recording by performing three transfer recordings. Further, from the viewpoint of color purity, it is particularly preferable that the cyan dye-containing layer contains the dye of the present invention.

[Effects of the Invention] By performing transfer recording using a transfer sheet containing the dye of the present invention, a record that can be read with light having a wavelength longer than 750 nm such as a semiconductor laser or a light emitting diode was obtained. In particular, by combining with sublimation transfer type yellow, magenta, and cyan transfer sheets, it was possible to obtain high-quality records such as full-color images with gradation and text information readable at 750 nm or higher.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of an integrated body of the present invention. Figure 1

Claims (1)

[Claims] A transfer sheet for thermal transfer recording, comprising a layer containing a transferable dye having an absorption maximum at a wavelength longer than 725 nm on a support.