JPS6287386A - Thermal transfer recording sheet - Google Patents

Abstract

PURPOSE:To prevent the title sheet from being fused to a recording paper at the time of transferring and prevent a sublimable dye from separating out to the surface of the sheet, by providing a coloring material layer comprising a sublimable dye and a binder on one side of a base film, while using a modified polycarbonate resin having a specified repeating structural unit as a binder. CONSTITUTION:A modified polycarbonate resin having a repeating structural unit of formula (I), wherein each or R<1> and R<2> is hydrogen, an alkyl or aryl, at least one of which is an aryl, is used as a binder for a thermal transfer recording sheet. The sheet is produced by dissolving the resin and a sublimable dye in an appropriate solvent to prepare an ink, applying the ink to a base film, and drying the ink. The modified polycarbonate resin has a glass transition temperature of 160-230 deg.C, and has excellent heat resistance. Therefore, when the resin is used as the binder, it is not softened or melted by the heat applied at the time of transfer recording, and is not fused to a recording paper, so that favorable recording can be achieved.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a thermal transfer recording sheet.

Conventional technology An ink containing a sublimable dye, a binder, etc. is applied to one side of a base film to form a coloring material layer17, and the transfer recording sheet is heated by a heating means at the corner of a thermal head to form a transfer recording sheet. In the so-called sublimation type thermal transfer recording, in which the dye on the sheet is sublimated and transferred onto the recording paper, recording is performed.
□As the binder used to form the color material layer of the transcription recording sheet, a polymer composition with a melting point or softening point of 700°C or higher is used, and particularly suitable ones include acrylic resin, methacrylic resin, and polyester resin. Vinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl acetal, polyamide, polyvinyl alcohol, polycarbonate,
Polysulfone, polyether sulfone, cellulose resin, etc. are mentioned (Japanese Patent Application Laid-open No. 1983/1999).

In the above-mentioned recording method, it has become necessary to apply a higher temperature to the transfer recording sheet in order to speed up recording.
Therefore, the binder used for transfer recording sheets is
There is a demand for materials with better heat resistance.

However, the aforementioned acrylic resin, methacrylic resin,
Resins such as polyvinyl chloride, polyvinylidene chloride, and polystyrene have insufficient heat resistance, so during transfer, these resins soften or melt and fuse with the recording paper, making it difficult to obtain good recording.

In addition, the binder used in transfer recording sheets needs to be dissolved in a solvent or water when making ink silk, but resins such as polyamide, polycarbonate, polysulfone, and polyethersulfone have low solubility, and the solvents that can be used are halogen-based. It is limited to solvents and must be handled with care for safety and hygiene reasons.

Furthermore, the binder used in the transfer recording sheet is required to have good compatibility with the sublimable dye used together. If the compatibility between the binder and the pigment is poor, the pigment dissolved in the ink will precipitate as crystals on the film during drying after the ink is applied to the base film. When such a transfer recording sheet is used, during transfer recording, dye is transferred to non-printed areas due to contact with the recording paper, resulting in so-called scumming, which deteriorates the quality of the transfer recording. Nonionic dyes are generally used as sublimable dyes, but polyvinyl alcohol, cellulose resins, and the like have poor compatibility with these dyes and are therefore undesirable as binders for transfer recording sheets.

Points to be Solved by the Invention The present invention aims to provide a thermal transfer recording sheet that does not fuse with the recording paper during transfer and does not cause sublimable dyes to precipitate as crystals on the sheet.

As a means to solve the problem, the present invention provides a thermal transfer recording sheet having a coloring material layer containing at least a sublimable dye and a binder on one side of a base film. (In the formula, R' and R2 represent a hydrogen atom, an alkyl group, or an aryl group, and at least one of them represents an aryl group.) A modified polycarbonate resin having a repeating structural unit represented by the following is used. The modified polycarbonate resin used in the present invention can be obtained by reacting one or more phenolic compounds selected from the following general formula (11) with phosgene according to a conventional method.

R'bi (in the formula, R' and R1 have the same definitions as above) At that time, one or more phenolic compounds selected from the following general formula (Ill) may be used in combination.

-5O- or -80,- represents a covalent group;
Rm and R4 represent a hydrogen atom or an alkyl group, and R"
represents an alkylene group, and benzene rings A and B may have an alkyl group or a halogen atom) The amount of the phenol compound represented by the above general formula (N) is 30 to 700 parts. The amount of the phenolic compound represented by the general formula (nl) may be 90 parts by weight or less.

Specific examples of the phenolic compound represented by the general formula (II) include bis(4!-hydroxyphenyl)diphenylmethane, bis(41-hydroxyphenyl)phenylmethane, bis(lI-hydroxyphenyl)-/ -phenylethane, hel-bis(II-hydroxyphenyl)-/-phenylpropane, he/-bis(y
-Hydroxyphenyl)-/-phenylbutane.

Further, as specific examples of the phenolic compound represented by the general formula (1), bis(l-hydroxyphenyl)methane, /, l-bis(lI-hydroxyphenyl)ethane 1.2.2-his(II- hydroquinphenyl)propane, co-, novis(terhydroxyphenyl)butane,
λ1.2-Bis(41-hydroxy-3-methylphenyl)propane, Haco-bis(terhydroxy-3,S
-dimethylphenyl)furopane, co, -bis(lI-
Nobis(hydroxyary-A/)alkanes such as hydroxy-3,S-dibromophenyl)furopane, /, l-bis(terhydroxyphenyl)cyclopentane, to/-
Bis(hydroxyaryl)cycloalkanes such as bis(4t-hydroxyphenyl)cyclohexane, Q, Q
'-dihydroxydiphenyl ether, da, l'-dihydroxy-3,3'-dimethyldiphenyl ether, dihydroxydiarylethers, y, 4t'-dihydroxycyphaer sulfide, l, W'-dihydroxy-3,31-dimethyldiphenyl sulfide dihydroxydiaryl sulfides such as +,II'-dihydroxydiphenyl sulfoxide, <z,+'-dihydroxy-3.31-dihydroxydiaryl sulfoxide such as 31-dimethyldiphenyl sulfoxide, ri, tei'-
Examples include dihydroxydiarylsulfones such as dihydroxydiphenylsulfone and p,p'-dihydroxy-3,3'-dimethyldiphenylsulfone.

In addition, the reduced viscosity of the modified polycarbonate resin of the present invention (
η5p10) is measured in a 0.417 dl methylene chloride solution at −0° C., and includes a range of θ, here to /, and jθ.

This can be carried out by preparing an ink by dissolving the above-mentioned modified polycarbonate resin'f sublimable dye in a suitable solvent, applying this ink to a base film, and drying it.

Examples of sublimable dyes include nonionic azo-based, anthraquinone-based, azomethine-based, methine-based, indoaniline-based, naphthoquinone-based, quinophthalone-based, and nido-based dyes.

In addition to the above-mentioned modified polycarbonate resin and sublimable pigment, organic and inorganic fine particles, dispersants, antistatic agents, antiblocking agents, antifoaming agents, antioxidants, viscosity modifiers, etc. are added to the ink as necessary. can do.

As a solvent for preparing the ink, dioxane, toluene, THP, chlorobenzene, 0-dichlorobenzene, chloroform, methylene chloride, trichlene, etc. can be used, but non-halogen solvents are preferred from the viewpoint of safety and hygiene.

The concentration of the modified polycarbonate resin in the ink is in the range of 1 to 30, and the concentration of the sublimable dye in the ink is 7 to 3.
0%, preferably in the range of C, S to -0%.

Base films include capacitor paper, thin paper such as glassine paper, polyamide, polyimide, cellophane,
A plastic film with good heat resistance such as polyester is used.

The base film of Korera is provided with a heat-resistant retention layer made of heat-resistant resin on the back side of the coloring material layer as necessary to improve the running performance of the thermal head (Japanese Patent Application Laid-Open No. S-7-6). , a stick-preventing hole made of a highly slippery inorganic pigment and a thermosetting or high softening point resin material is provided (Japanese Patent Laid-Open No. 5
6-/jj7?4), a wear-resistant heat-retaining layer selected from a silicon oxide layer or a three-dimensional crosslinked layer of polyfunctional (meth)acrylates (% 1987-71 I/f) ) or the like may be used.

In addition, these base films are made of water-soluble polyester resin on the ink-applied surface of the base film in order to improve adhesion with ink, prevent dyes from staining the base film, and improve heat conduction from the base film to the coloring material layer. A material treated with a resin such as cellulose resin, polyvinyl alcohol, urethane resin, or polyvinylidene chloride, or a material on which a thin aluminium film is formed may also be used.

The appropriate thickness of these base films is 3 to -5 μm.

Methods for applying ink to the base film include, for example, the gravure coater shown in Yuji Harasaki's "Coating Method" (/97?) (Maki Shoten), the reverse roll coater,
This can be carried out using a wire bar coater, an air doctor coater, etc.

The thickness of the ink coating layer is the wet film thickness θ, /~S
The dry film thickness ranges from 0.07 to 3 μm.
The scope of

To perform recording using the thermal transfer recording sheet of the present invention, the color material layer of the nuclear thermal transfer recording sheet is superimposed on the recording paper,
For example, this is carried out by heating the back side of the color material layer of a nuclear thermal transfer recording sheet using a thermal head that generates heat using an electric signal corresponding to image information, but infrared rays, laser light, etc. can also be used as a heating means. can.

Effects and Effects The chewable polycarbonate tree JI'rIH1 of the present invention has a glass transition temperature between 1bo and t3oC and has excellent heat resistance, so it was used as a binder for thermal transfer recording sheets. In this case, the thermal transfer recording sheet will not be softened or melted by the heat during transfer recording, and the thermal transfer recording sheet will not be fused to the recording paper, making it possible to obtain good recording.

Nineth, the modified polycarbonate resin used in the present invention has excellent compatibility with organic solvents, so it can be sufficiently dissolved in bath agents for non-halogen yarns such as toluene, dioxane, and tetrahydrofuran (THF). Ink can be prepared using these solvents, and there are few safety and health problems when handling the ink.

Since the modified polycarbonate resin used in the present invention has good compatibility with nonionic sublimable dyes, the ink is applied to the base film and the dyes crystallize on the film even after dry recording. It does not precipitate as

EXAMPLES The present invention will be specifically explained using actual distance measurement in Examples, but the present Examples are not intended to limit the present invention.

Example I (,) Ink manufactured by IAi A phenol compound shown in M/* below was reacted with phosgene according to a conventional method to produce a modified polycarbonate resin of the present invention.

Reduced viscosity (η5p) of the obtained modified polycarbonate resin
10) and glass transition points are shown in Table 1.

= 12 ~ When an ink with the following composition was prepared using toluene, dioxane, and THF in a solvent, it was possible to obtain a uniform ink in which the modified polycarbonate resin and sublimable dye were completely dissolved. .

Ink composition modified polycarbonate resin 10 weight 1
Parts (AI, C, 3, +1 or j in Table 1) Sublimable dye (Structural formula [■] below) 6N Total parts
100 weight @ part structural formula (IV') (b) Creation of thermal transfer recording sheet As a base film, the above ( Apply the ink of a) using a wire bar to a wet film thickness of 6 μm,
A thermal transfer recording sheet was obtained by drying.

At this time, the dye did not crystallize even after drying with the ink, and it was possible to obtain a completely transparent and uniform magenta thermal transfer recording sheet.

(0) Transfer recording test and results The thermal transfer recording sheet prepared in (b) above was laminated with a recording paper having a blood-colored layer containing polyester resin and fine silica on the surface, and the heating resistor density was determined as follows:
0.g using a thermal head. , tW/dot was applied for a period of ~10 milliseconds, and as a result, each transfer sheet did not fuse with the recording paper, and
The binder on the transfer sheet did not transfer to the recording paper, and the transfer sheet and the recording paper could be easily separated after recording.

In addition, all the records obtained showed good resolution of each dot, a clear magenta color, and good gradation depending on the application time.

Table 1 below shows the color density of the transfer test results of the transfer sheet made using ink prepared using toluene as a solvent. I was able to obtain a good record.

=16= Color density was measured with a Macbeth TR-9,27 densitometer using a ratten aS filter.

Example 1 Ink was prepared and a thermal transfer recording sheet was prepared in the same manner as in Example 1, except that a cyan dye represented by the following structural formula (v) was used in place of the dye used in Example 1. As a result, it was possible to create a cyan ink in which the sublimable dye and modified polycarbonate resin were completely dissolved, and a transparent and uniform cyan-colored thermal transfer recording sheet, which was at risk of precipitation of the dye on the sheet. Furthermore, as in Example 1, transfer recording was performed using these thermal transfer recording sheets, and as a result, the thermal transfer recording sheet and the recording paper did not fuse together, and clear cyan with good gradation was obtained. I was able to get a color record.

Structural formula [V] Hs Table 3 below shows the color densities of transfer test results of thermal transfer recording sheets prepared using inks prepared using toluene as a solvent.

The third color density was measured using the same densitometer as in Example using a Ratten/I6.2j filter.

Example 3 Ink was prepared and a thermal transfer recording sheet was prepared in the same manner as in Example, except that a yellow dye represented by the following structural formula (■) was used instead of the dye used in Example. It was possible to create a transparent and uniform yellow thermal transfer recording sheet with no dye precipitation on the ink and sheet in which the sublimable dye and modified polycarbonate resin were completely dissolved. In addition, as a result of performing transfer recording using these thermal transfer recording sheets in the same manner as in Example, the thermal transfer recording sheet and the recording paper were often fused together, resulting in a clear yellow with good gradation. I was able to get a color record.

Structural formula [Vl] Table 1 below shows the color density of the transfer test = 19- results of a transfer sheet prepared using PL ink using toluene as a solvent.

The ninth color density was measured using the same densitometer as in Example 1 using a Wratten filter.

Comparative Example/An ink having the same composition as in Example was prepared using the resin shown in Table 3 below in place of the resin used in Example, and toluene, dioxane, and THF were used as solvents.

Although the ink was prepared using methyl ethyl ketone, ethyl acetate, cellosolve, water, etc., in all cases, the resin of cliff/~A41' in Table 5 was not completely dissolved in the solvent and a uniform ink was prepared. I couldn't do it.

In addition, for the resins A5 to &10 in Table S, uniform inks in which the resins and pigments were completely dissolved could be prepared using various solvents. When a recording sheet was prepared, dye crystals were deposited on the sheet, and a uniform thermal transfer recording sheet could not be prepared. Transfer tests were conducted using these thermal transfer recording sheets, and as a result, background smear occurred in all cases.

In addition, when the thermal transfer recording sheet using the SS-flat resin in Table J is applied for a long time, it fuses with the recording paper.
I couldn't get a good record.

Table 5

Claims (1)

[Claims] (1) In a thermal transfer recording sheet having a coloring material layer containing at least a sublimable dye and a binder on one side of the base film, the binder has the following general formula (I) ▲Mathematical formula, chemical formula, table, etc.▼(I ) (wherein R^1 and R^2 represent a hydrogen atom, an alkyl group, or an aryl group, and at least one represents an aryl group). A thermal transfer recording sheet.