JPS6233687A - Sheet for thermal transfer recording - Google Patents

Abstract

PURPOSE:To prevent a title sheet from fusing to a recording paper in transferring and a subliming dyestuff from depositing in the form of crystal on the sheet, by a method wherein a coloring material layer containing at least a subliming dye and a binder is formed on one side surface of a base film and a specific modified polycarbonate resin is used as the binder. CONSTITUTION:As a binder, a modified polycarbonate resin having repeated structural units as represented by a formula (I) is used. (In the formula, both R<1> and R<2> represent hydrogen, alkyl, and aryl and either one is represents aryl.) the resin of 160-230 deg. glass transition temperature is sperior in heat resistance, therefore have no possibility of softening or melting when subjected to the heat generated during transfer recording, which prevents a sheet for thermal transfer recording from fusing to a recording paper. Furthermore, after the ink has been applied and dried on a base film, a good compatibility of the resin with a nonionic subliming dyestuff prevents the dyestuff from depositing in the form of crystal on the base film.

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 and a binder is applied to one side of the base film to form a coloring material layer, and then the transfer recording sheet is heated using a heating means such as a thermal head to perform the transfer. The dye on the recording sheet is sublimated and transferred onto the recording paper,
In so-called sublimation heat-sensitive transfer recording, a polymer composition having a melting point or softening point of 100° C. or higher is used as a binder for forming a coloring layer of a transfer recording sheet, and particularly suitable ones include: , acrylic resin, methacrylic resin, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl acetal, polyamide, polyvinyl alcohol, polycarbonate, polysulfone, polyether sulfone, cellulose resin, etc. 9t9ri No. 9 Publication)
.

In the above-mentioned recording method, it is necessary to apply a higher temperature to the transfer recording sheet in order to increase the recording speed.
Therefore, the binder used for transfer recording sheets is
A material with good heat resistance is required.

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.

Furthermore, binders used in transfer recording sheets need to be dissolved in a solvent or water when preparing ink, but resins such as polyamide, polycarbonate, polysulfone, and polyethersulfone have low solubility, and the only solvents that can be used are halogen-based solvents. Due to safety and health concerns, certain precautions must be taken when handling the product.

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 when the ink is dried 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 not preferred as binders for transfer recording sheets.

Problems to be Solved by the Invention In the present invention, the sublimable dye does not fuse with the recording paper during transfer, and the sublimable dye precipitates as crystals on the sheet. In a thermal transfer recording sheet having a coloring material layer containing a dye and a binder, the binder is represented by the following general formula (I) (in the formula,
The object of the present invention is to provide a thermal transfer recording sheet characterized by using a modified polycarbonate resin having a repeating structural unit represented by R2Fi (representing a hydrogen atom, an alkyl group, or an aryl group, at least one of which represents an aryl group).

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 (n) with phosgene according to a conventional method.

RZ (wherein R1 and RZ 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.

Represents a covalent group represented by -5O- or -802-,
R3 and R4 represent a hydrogen atom or an alkyl group, and R6
represents an alkylene group, and the benzene rings A and B may have an alkyl group or a halogen atom) The amount of the phenolic compound represented by the above general formula (■) is 30 to 10 θ parts by weight. The amount of the phenolic compound represented by the general formula (III) used is 70 parts by weight or less.

Specific examples of the phenolic compound represented by the general formula (II) include bis(Hiro-hydroxyphenyl)diphenylmethane, bis(terhydroxyphenyl)phenylmethane, /,/-bis(terhydroxyphenyl)-
/-phenylethane, /, /-bis(terhydroquiphenyl)-/-phenylpropane, /, /-bis(4t
-Hydroxyphenyl)-/-Phenylbuta 7 etc. List I
ff I'm happy.

Specific examples of the phenolic compound represented by the general formula (III) include bis(terhydroquiphenyl)methane, /,/-bis(Hiro-hydroxyphenyl)ethane, and 2-bis(4t-hydroxyphenyl). Propane, Co, Corbis (4t-hydroxycuphenyl)butane,
Tip 2-bis(gu-hydroxy-3-methylphenyl)
Propane, 2-bis(4t-hydroxy-3,j-
dimethylphenyl)furopane, 2. ．． Nobis(hydroxyaryl)alkanes such as 2-bis(terhydroxy-3,j-dibromophenyl)propane, /, /-bis(
4t-hydroxyphenyl)cyclopentane, /, /-
Bis(hydroxyaryl)cycloalkanes such as bis(terhydroxyphenyl)cyclohexane, %, 4
t'-dihydroxydiphenyl ether, da, St/-
Dihydroxydiaryl ethers such as dihydroxy-3,3'-dimethyldiphenyl ether, %,%'-dihydroxydiphenyl sulfide, dihydroxydiaryl sulfides such as p,p'-dihydroxy-3,3'-dimethyldiphenyl sulfide, p, e Dihydroxydiaryl sulfoxides such as '-dihydroxydiphenyl sulfoxide, %, %'-dihydroxy-3,3'-dimethyldiphenyl sulfoxide, a, q'-
Examples include dihydroxydiarylsulfones such as dihydroxydiphenylsulfone, %, llt'-dihydroxy-3,3'-dimethyldiphenylsulfone, and the like.

In addition, the reduced viscosity of the modified polycarbonate resin of the present invention (
ηsp/(3) is measured in a methylene chloride solution of θ, tv7cxt at 20° C. and ranges from 0.22 to θ, 7θ.

In order to prepare the thermal transfer recording sheet of the present invention, an ink is prepared by dissolving the above-mentioned modified polycarbonate resin and a sublimable dye in a suitable solvent, and this ink is applied to a base film and dried. It can be implemented by

Examples of sublimable dyes include nonionic azo-based, anthraquinone-based, azomethine-based, methine-based, indoaniline-based, naphthoquinone-based, quinophthalone-based, and nitro-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, THF, 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 2 to 50%, preferably j to 3θ, and the concentration of the sublimable dye in the ink is 7 to 30%.
Preferably, the range is from -05% 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.

These base films include a heat-resistant protective layer made of a heat-resistant resin on the back side of the color material layer as necessary to improve the running properties of the thermal head (%Kaimei!1f-74tdZ publication), and a highly slippery inorganic film. A stick prevention layer consisting of a pigment and a thermosetting resin material with a high softening point is provided (Japanese Unexamined Patent Application Publication No. 1985-1989-1/JJ7-9), a silicon oxide layer or a polyfunctional (meth)acrylate layer. It may be treated by a known method such as providing an abrasion-resistant and heat-resistant protective layer selected from a three-dimensional crosslinked layer (% 1987-7%/Regular Publication).

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 aluminum film is formed may also be used.

The film thickness of these base films is 3~! μm is the suitable tooth.

Examples of methods for applying ink to the base film include gravure coater, +) bar roll coater, ``) e-Y bar coater, and air doctor coater as shown in Yuji Harasaki's ``Coating Method'' (/ri2ri) (Maki Shoten). This can be done using, for example.

The thickness of the ink coating layer is wet film thickness θ, /~j
The range of θμ is listed, and the dry film thickness θ, θ/~! μm
The range of

To perform recording using the thermal transfer recording sheet of the present invention, the color material layer of the thermal transfer recording sheet is superimposed on a recording paper,
For example, this is carried out by heating the coloring material layer of the thermal transfer recording sheet from the back side using a thermal head that generates heat using electric signals according to image information.
Laser light can also be used.

Functions and Effects The modified polycarbonate resin of the present invention has a glass transition temperature of 740 to 230°C and has excellent heat resistance. The thermal transfer recording sheet does not melt or melt due to heat, and the thermal transfer recording sheet does not fuse to the recording paper, making it possible to obtain good recording.

Next, the modified polycarbonate resin used in the present invention has excellent solubility in organic solvents, so it melts well in non-halogen solvents such as toluene, dioxane, and tetrahydrofuran (THF). Furthermore, inks can be prepared using these solvents, and there are fewer health and safety problems when handling the inks.

Since the modified polycarbonate resin used in the present invention has good compatibility with nonionic sublimable dyes, the dyes do not precipitate as crystals on the film even after the ink is applied to the base film and dries. There is no.

EXAMPLES The present invention will be specifically explained with reference to Examples, but these Examples do not limit the present invention.

Examples/(a) Preparation of ink A modified polycarbonate resin of the present invention was produced by reacting the phenol compounds shown in Table 1 below with phosge according to a conventional method.

The reduced viscosity (η8
T)/CI) and glass transition point as shown in Table 1. When ink with the following composition was prepared using toluene, dioxane and TIF, the modified polycarbonate resin and sublimable dye were completely absorbed. It was possible to obtain a uniform ink that was dissolved in

Ink composition modified polycarbonate resin 70 parts by weight (first
A/, K, 3 or Hiroshi in the table) Sublimable dye (Structural formula (IV) below) 4 parts by weight Structural formula (■) (1,) Creation of thermal transfer recording sheet As a base film, the back side of the ink-applied surface A heat transfer recording sheet was obtained by coating with a wet film thickness ≦ μm using a heat-resistant polyimide resin and 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 color developing layer containing polyester resin and fine silica on the surface, and the heating resistor density was determined. θ, 2W/dot power /~1 using dot/WI thermal head
As a result of applying the voltage for 0 milliseconds and recording, 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 after recording,
The transfer sheet and recording paper could be easily separated.

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

Table 2 below shows that a transfer sheet prepared using toluene as a solvent and using the following ink was able to obtain a good transfer record.

Table 2 □-1 Color density was measured with a Macbeth TR-ta 27 densitometer using a Ratten Aj♂ filter.

Ink was prepared and a thermal transfer recording sheet was prepared in the same manner as in Example, except that a cyan dye represented by the following structural formula (V) was used instead of the dye used in Example. After the sublimable dye and the modified polycarbonate resin were completely dissolved, it was possible to produce a cyan ink and a transparent and uniform cyan-colored thermal transfer recording sheet without precipitation of the dye on the sheet. In addition, as in Example 1, transfer recording was performed using these thermal transfer recording sheets, and the thermal transfer recording sheet and the recording paper did not fuse, and a clear cyan color with good gradation was obtained. I was able to obtain a record of

Structural Formula (V) H3 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 is Ratsuten tFa2! It was measured with the same densitometer as in Example/using the same 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 (Vl) was used instead of the dye used in Example. However, the sublimable dye and the modified polycarbonate resin were completely dissolved, and a transparent and uniform yellow thermal transfer recording sheet with no precipitation of the dye on the ink or sheet could be produced. In addition, transfer recording was carried out using these thermal transfer recording sheets in the same manner as in Example/. Structural formula (■) The following table shows the transfer test results of transfer sheets prepared using ink prepared using toluene as a solvent. Indicates the color density of

The color density was measured using a RATSUTENYA≠7 filter with the same needle as in Example.

Comparative Example/An ink having the same composition as Example/ was prepared using the resin shown in Table 5 below instead of the resin used in Example/.
It was prepared using toluene, dioxane, THF, methyl ethyl ketone, ethyl acetate, cellosolve, water, etc. as a solvent.
Regarding the Ada resin, in all cases the resin was not completely dissolved in the solvent and a uniform ink could not be prepared.

Also, Table 5 Nakabian! ~ Regarding the A/θ resin, we were able to prepare uniform ink in which the resin and pigment were completely dissolved using various solvents, but these inks were applied to a base film and dried to create a thermal transfer recording sheet. As a result, dye crystals were deposited on the sheet, making it impossible to produce a uniform thermal transfer recording sheet. 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 resin Jfa j -A 7 in Table 5 was applied for a long time, fusion occurred with the recording paper, and good recording could not be obtained.

Claims (1)

[Claims] (1) In a thermal transfer recording sheet that has 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.