JPH01154794A - Thermal transfer sheet - Google Patents

Abstract

PURPOSE:To perform printing with high resolution and excellent image quality stably at high speed without causing adhesion of a film to a high-temperature thermal head or troubles in feeding the film at the time of heating by the head, by adopting a base sheet comprising a specified polycarbonate resin as a base of a thermal transfer sheet. CONSTITUTION:A polycarbonate resin having a weight average molecular weight of 100000-250000 is used. If the weight average molecular weight is greater than the range, solubility of the resin in a solvent is poor, and it is difficult to prepare a film from the resin, whereas if the molecular weight is less than the range, the resin is liable to be modified by the heat supplied from a thermal head at the time of thermal transfer. A heat-resistant film stretched to a minimized thickness of several micrometers to several tens of micrometers must be subsequently heat-treated to enhance dimensional stability. The heat-treating temperature is preferably as high as possible, and is generally set to be higher by 10-20 deg.C than the melting point of the polycarbonate resin constituting a base sheet, whereby a film can be obtained which has high dimensional stability at high temperatures, is insusceptible of shrinking deformations, and can be used as a heat-resistant film for transfer-type thermal recording.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a transfer sheet which is a recording method that transfers a coloring material (thermal ink) by applying heat.

[Prior art]

In recent years, with the rapid development of the information industry, various information processing systems have been developed, and recording methods and devices suitable for each information processing system have also been developed and adopted. One such recording method is the thermal recording method, which uses light chain, compact, and noiseless equipment, has excellent operability and maintainability, and is easy to colorize, and has recently become widely used. There are roughly two types of thermal transfer recording methods.The first method involves applying heat to the heat-melting ink coated on the support from the support side. The second method is to melt a 7g turn and transfer it to a recording medium.The second method is to apply heat from the support side to a heat-sensitive recording material made of a resin with a high softening point and a sublimable dye on a support. This method involves sublimating a sublimable dye in a pattern and transferring it to a recording medium.

The thermal transfer method described above is a method in which an ink layer is provided on one side and the other side of the ink film is heated with a thermal head to melt the ink layer or vaporize the sublimable dye in the ink layer and transfer it onto plain paper. Conventionally, the base film of the ink film is a thin film of a polymer such as polyester or polyamide, or a thin paper such as condenser paper or glassine paper. In such thermal transfer methods, the performance of the ink film is greatly affected by printing speed and image quality.

By the way, recently there has been an increasing demand for higher image quality and faster printing speeds, and in order to meet these demands, it is necessary to transfer high resolution dots and e-turns in an extremely short time. has been done. In order to obtain a dot pattern with high resolution, it is necessary to make the area of each dot small, and in order to transfer it in a short time, (1)
Possible methods include raising the temperature of the thermal head, (2) using an ink layer using a low-melting point or low-temperature sublimable dye, and (3) making the base film thinner to increase its thermal conductivity. , method 2) has problems in terms of ink layer stability and printing reliability, method (3) has problems in film strength and wrinkle generation, and method (1) has problems with the temperature of the thermal head. In addition, it is necessary to reduce the dot area (then, from the viewpoint of effective thermal efficiency per area, it is necessary to increase the temperature of the thermal head).

In this way, it is generally necessary to raise the temperature of the thermal head to 3005-IAOOoC in order to increase speed and improve image quality, but at this temperature, films made of conventional thermoplastic polymers do not melt. ,
There is a problem in that stable running is difficult due to adhesion with the head or deformation due to pressurization and heating of the head. On the other hand, even if films made of non-thermoplastic polymers such as cellophane or polyimide films can solve the above problems, they are not practical in terms of stability over time and economic efficiency.

[Problem that the invention seeks to solve]

The purpose of the present invention is to solve these problems, to avoid adhesion between the head and the film during heating by a high-temperature thermal head, and to ensure stable printing with high resolution and excellent image quality at high speed. The purpose of the present invention is to provide a heat-sensitive transfer sheet that can be used for printing.

[Means to solve the problem]

As a result of intensive research to solve the above-mentioned drawbacks of the conventional technology, the present invention adopts a base sheet made of polycarbonate resin in place of the base sheet of the conventional heat-sensitive transfer sheet, thereby solving the above-mentioned problems. The present invention was completed based on the knowledge that this problem could be solved.

That is, the present invention provides a heat-sensitive transfer sheet having a heat-sensitive transfer layer on one side of a base sheet, wherein the base sheet is made of a polycarbonate resin having a weight average molecular weight of 100,000 to 250,000. It is.

Polycarbonate resin is a polymer resin with a carbonate ester structure in the structural unit, and -E-0-X-0-C in the shell.
-) II”.

As for X, -(CH2); (X: 31 ”@
3m &, 10), -(CH2) 20(CH2) 2-
R2R3 atom, alkyl group), etc. are known.

In order to achieve the purpose of the present invention, the molecular weight of the polycarbonate resin must be too large (or too small).
A material having a weight average molecular weight of toO,000 to 2jO,000 is used. If the weight average molecular weight is larger than this range, the solubility in solvents will deteriorate, making it difficult to produce a film.On the other hand, if it is smaller than this range, it will be easily denatured by the heat of the thermal head during thermal transfer. Those having an average molecular weight of 10,000 to 23-0.000 are preferred.

In a preferred embodiment of the invention, the polycarbonate is bisphenol A polycarbonate. In another preferred embodiment of the invention, the bisphenol A polycarbonate comprises a polymer having the formula % where n is from ≠00 to tooo.

The base sheet in the present invention is preferably used as a five-sided film with a size of several microns to several tens of microns, and is therefore more effective than using a uniaxially or biaxially stretched film after molding. Methods for stretching the film include biaxial stretching using a tenter, inter-roll-axial stretching in which stretching is performed while applying tension between rolls, and rolling in which uniaxial stretching is performed by adding a rolling blade between rolls. Yes, either method can be used.

The heat-resistant film stretched in this manner needs to be heat-treated after stretching to improve its dimensional stability. The temperature at which the heat treatment is performed is preferably as high as possible, and it is usually effective to carry out the heat treatment at a temperature 70% 2o6C lower than the melting point of the polycarbonate compound constituting the base sheet. By performing the heat treatment at a high temperature, the dimensional stability of the base sheet is improved, and shrinkage deformation hardly occurs at high temperatures. The film thus obtained has good dimensional stability at high temperatures, does not undergo shrinkage deformation,
It can be used as a heat-resistant film for transfer-type heat-sensitive recording.

The polycarbonate resin film used as the base sheet of the heat-sensitive transfer sheet in the present invention is similar to the base sheet of the conventional heat-sensitive transfer sheet. Oμm, preferably 3~
/jμm, and in terms of shape, it may be in the form of a single sheet cut to a predetermined size (or it may be continuous or rolled (or it may be in the form of a narrow tape). There may be.

The main feature of the heat-sensitive transfer sheet of the present invention is that it uses a specific base sheet as described above, and in the first embodiment, the heat-sensitive transfer layer provided on the base sheet as described above is This embodiment is a heat-sensitive sublimation transfer layer comprising a migratory dye and a binder resin. The heat-sensitive transfer sheet of this embodiment is prepared by preparing a coating solution by dissolving or dispersing a conventionally known heat-transferable dye, that is, a sublimation-transferable dye, and a binder resin in an appropriate solvent. on one surface of the base sheet made of the polycarbonate resin, for example, about 0.2 to 3.0 μm, preferably 0.4 μm.
It is obtained by coating in a coating amount to give a dry film thickness of m2.0 μm and drying to form a heat-sensitive sublimation transfer layer.

As the dye useful for forming such a heat-sensitive sublimation transfer layer, any sublimable dye conventionally used in heat-sensitive sublimation transfer sheets can be used, but particularly preferred in the present invention are about tzo-to- .

It has a relatively low molecular weight, and should be selected in consideration of sublimation temperature, hue, light resistance, solubility in ink and binder resin, dispersibility, etc.

Specifically, for example, disperse dyes, basic dyes, oil-soluble dyes, etc. are used, and in particular, Sumikalon Yellow E4'GL, Dyanix Yellow HJG-FS, Miketon Polyester Yellow 3GSL, Kayaset Yellowta 37 , Sumikalon Red EFBL, Dianic Red ACE, Miketon Polyester Red FB1 Kayaset Lend/26, Miketon Fast Brilliant Blue B.

Kayaset Blue/36 or the like is preferably used.

Also, JP-A-J Tar'yr, Ryz, 4O-2r, a
rt, tsO-21r, 1113, 6O-1
s, rA', 7. /-/ul, 0ri No. 6, same 60
-23ri1.2ri0, same 40-3/, Taro! No. 4
0-30. Jri No. 3, same 1.0-! 3゜545, same 4
No. 0-27.19μ, No. 61-262, No. 1, No. 1
．． 0-/! 12. jAJ No. 4/-J4C4C, 32
No. 5, and the sublimable yellow dye described in No. 62-l 6゜114, No. 10-223, It, No. 2, No. 60-
21. ≠Taco, 60-3/,! No. 63, same ry-t
l, rY&, 60-3/, jA4', AO-
30, jri No. 1, same 1. /-227,0 Octopus, same 1.
/-227゜0ri No. 1 60-30. J Taco No. 40
-303 Tada issue, 1aO-/3/, 2ri 3, 4/
-227,023, same t O-/t, Ori No. 1,
41-242. /ri No. 0, U.S. Patent μ, 6rit.

6ta No. 1 and Japanese Patent Application No. 62-220,723) sublimable magenta dye described in K, JP-A-Sho! Day'yr, ryu issue, Tatar 227, uri 0,
same tao-tri, ori wo issue, same tao-tri 227.4c9
No. 3, No. 4/-J$4', No. j2μ, Tatako, No. 2
7.2μ No., same to-i31.2ri No. 2, same to-i 60-1
72. jri No. 1, same to-o ta/, 027, same 1.0
-/3/, 22μ issue, 1,0-2/7, 21a6 issue,
40-31゜552, 60-13. ! No. 63, No. 61-cozz, ry'y, No. 60-23, No. 21, No. 61-22. Tata No. 3, same 1. /-1 ri, 3ri No. 6, 41-241.4c ri No. 3, same 6t-JB9Pμ, same 1. /-3/, μ67, same 1. /-/μt.

No. 26, same tt-ay, r no. 3, same 4/-r7.4
j1 No. 60-23, No. 221, No. 0-239.
2 Octopus, 4i-2ru, 4cry, 1s2-
/ri/, No. 127 and Japanese Patent Application No. 171/1989. ．． 421
The sublimable cyan dye described in No. 1 (Using a dye represented by the general formula) is also suitably used.

Furthermore, as the binder resin used with the above dye, any binder resin conventionally known for this purpose can be used, and usually has high heat resistance and does not hinder the transfer of the dye when heated. For example, polyamide resin, polyester resin,
Epoxy resins, polyurethane resins, polyacrylic resins (e.g. polymethyl methacrylate, polyacrylamide), vinyl resins including polyvinylpyrrolidone, polyvinyl chloride resins (e.g. vinyl chloride-vinyl acetate copolymers, etc.), Cellulose-based m)]tT (e.g. methylcellulose, ethylcellulose, carboxymethylcellulose, etc.), polyvinyl alcohol-based resins (e.g. polyvinyl alcohol, partially saponified polyvinyl alcohol, etc.), petroleum-based resins, rosin derivatives, coumaron-indene resins, terpene-based resins, Novolac type phenolic resin, polystyrene resin, polyolefin resin (
For example, polyethylene, polypropylene), etc. are used.

Such binder resins include, for example, Dye I.

It is preferred to use about 50 to 100 parts by weight per 0 parts by weight.

In the present invention, as the ink solvent for dissolving or dispersing the above-mentioned dye and binder resin, conventionally known ink solvents can be freely used. Specifically, alcohol-based ink solvents include methanol, ethanol, isopropyl alcohol, butanol, Examples of the solvent include butanol, ketones such as methyl ethyl ketone, methyl isobutyl ketone, and microhexanone; aromatic solvents such as toluene and xylene; halogen solvents such as dichloromethane, trichloroethane, diquinane, and tetrahydrofuran; and mixtures of the above solvents. It is necessary to select and use these solvents so that the dye used has a predetermined concentration or higher and the binder resin is sufficiently dissolved or dispersed. For example, it is preferable to use a solvent in an amount of about t to 20 times the total amount of the dye and binder resin.

The preferred embodiment of the heat-sensitive transfer sheet of the present invention obtained as described above is laminated with a conventionally known heat-sensitive transfer sheet,
By heating from any side, preferably from the surface of the thermal transfer sheet, using a heating means such as a thermal head according to the image signal, the dye in the thermal transfer layer can be easily transferred to the thermal transfer sheet with relatively low energy. The color image is transferred to the receiving layer according to the magnitude of the heating energy, and a color image with gradations of sharpness and resolution can be formed.

A slipping layer may be applied to the back side of the thermal transfer sheet to prevent the print head from sticking to the thermal transfer sheet. Slipping layers of this type consist of lubricants, such as surfactants, liquid lubricants, solid lubricants or mixtures thereof, with or without high molecular weight binders.

A second preferred embodiment of the present invention is an embodiment in which the heat-sensitive transfer layer of the heat-sensitive transfer sheet is a heat-sensitive melting transfer layer comprising a dye or pigment and wax.

In the heat-sensitive transfer sheet of this embodiment, an ink for forming a heat-sensitive transfer layer made of wax containing a coloring agent such as a dye or pigment is prepared on one surface of the specific base sheet as described above, and a heat-sensitive transfer layer is formed from the ink. It is obtained by forming a transfer layer. The ink is made by blending and dispersing a wax with an appropriate melting point, such as paraffin wax, microcrystalline wax, carnauba wax, urethane wax, etc., and colorants such as carbon black, various dyes, and pigments. It is what it is. The ratio of the dye or pigment to the wax to be used is preferably in the range of about io to 47% by weight of the dye or pigment in the heat-sensitive melt transfer layer to be formed (and the thickness of the layer to be formed is about io to 47% by weight).
．． A range of 0 μm is preferred. Their manufacture and application onto a substrate film can be carried out according to known techniques.

When the heat-sensitive transfer sheet of the present invention in the second preferred embodiment as described above is used in the same manner as in the first embodiment, the heat-sensitive melting transfer layer is transferred to the transfer sheet, giving uneven printing.

EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited by these Examples.

Note that "%" or "%" in the text is based on weight.

Example 1 A film having a thickness of t μm was obtained by dissolving 10 f/ of the following polycarbonate resin (having repeat units (weight average molecular weight/10,000)) in 200 rrl of ethylene chloride, pouring it onto a mirror-finished metal flat plate, drying it, and then peeling it off. I got it.

H3 A thermal transfer sheet (a) was obtained by applying the following layers to this film in the following order.

l) Pigment barrier layer of gelatin nitrate (gelatin and cellulose nitrate, weight ratio approximately 2:l, in solvents primarily acetone and methanol) (0,2097 m2), applied from acetone and water bath.

2) Ink composition for thermal transfer layer Disperse dye (Nippon Kayaku Co., Ltd., Kayaset Blue TXT) g part Polyvinyl butyral resin (electrochemical system, rooo-A) 41 parts isopropyl alcohol μθ part n-butanol
A slipping layer of poly(vinyl stearate) (o, 76 II/m) in cellulose acetate butyrate (0°3317 m'') was applied to the back side of 4 co of this sheet from a tetrahydrofuran solvent.

Also, the weight average molecular weight is 2! .

Furthermore, polycarbonate with a weight average molecular weight of 3!0.000 is difficult to dissolve in solvents (and a film could not be formed).

Next, as a base material, synthetic paper (manufactured by Tamago Yuka Co., Ltd.,
YUPO-FPG/! A thermal transfer sheet was prepared by applying an ink composition for a receptor layer having the following composition using Wire Par coating to give a dry thickness of tg7m2. Drying: After temporary drying with a hair dryer,
00 (::) oven for 1 hour to sufficiently volatilize the solvent.

Receiving layer ink composition Vylon 103 (manufactured by Toyobo, polyester resin) r part Elpaloy 7 μl (manufactured by Mitsui Polychemicals, EVA-based polymer plasticizer) 2 parts amino-modified silicone oil (manufactured by Shin-Etsu Silicone, KF-3RIJ) 0. 121 parts epoxy-modified silicone oil (manufactured by Shin-Etsu Silicone, X-, 2, 2- 3≠j) 0. /2J part toluene 70 parts methyl ethyl ketone io part cyclohexanone
20 copies of the thermal transfer sheet obtained as described above) (
a) and the thermal transfer sheet are stacked at ℃ such that the thermal transfer layer and the receiving layer are in contact with each other, and the output of the thermal head is 1W/1 dot by a thermal head from the support side of the thermal transfer sheet.
e /l/, X width; o, 3~tA, tmsec,
As a result of recording under the conditions of dot density: 3 dots/fi, no sticking phenomenon of the thermal head was observed, and the coating material density in the high-density coloring part with pulse width u and jmsec was 1. It is kota, and the nose width is 0. The Jmsec part is 0. /3, and a record with gradation according to the applied energy was obtained (measuring instrument: Macbeth densitometer RD-ta/
If), after printing with the thermal head, when the thermal transfer sheet and the thermal transfer sheet are peeled off, there is no transfer of the resin in the thermal transfer layer, and there is no background staining on the non-heated areas. Also, when the transfer operation was performed in the same manner as above using the comparative sheet (b), the sheet softened due to the heat of the thermal head and did not peel off from the transfer sheet (
It is had.

Treatment Example 2 Composition of hot melt ink Neozapon blue ro'y <coloring dye) (manufactured by BASF)
10 parts lanolin fatty acid barium salt
30 parts carnauba wax 2
0 parts paraffin wax 20 parts powder 0.1 parts liquid paraffin
! Ink y+, r with the above composition
The mixture was sufficiently dispersed in a ball mill for about ψt hours with a mixture of 7,100 parts of methyl ethyl keto and 130 parts of toluene.

Next, 300 parts of a 20 wt % vinyl chloride-vinyl acetate copolymer resin solution (10 parts of resin, 20 parts of toluene, 20 parts of methyl ethyl ketone) was added to the above ink dispersion and dispersed in a ball mill for about 1 hour to form a thermal transfer composition. I created a paint for things.

This coating material was applied to the surface of the polycarbonate film of Example 1 on which the slipping layer was formed using a wire parser, and dried for 1 minute at a drying temperature of IOO'C to a thickness of about t.
A heat-melting ink layer with a thickness of μm was formed.

When printing was performed using a printing machine equipped with a thermal head (manufactured by Toshiba, p-/610), clear printing with blue ring spacing was achieved.

〔Effect of the invention〕

According to the heat-sensitive recording material of the present invention, it is possible to maintain sufficient heat resistance even when the support is thin, and it is smooth and has good dimensional stability, and it is possible to obtain a good full-color image even in high-speed recording. can.

Claims (4)

[Claims] (1) In a heat-sensitive transfer sheet having a heat-sensitive transfer layer on one side of the base sheet, the base sheet has a weight average molecular weight of 100
A heat-sensitive transfer sheet comprising a polycarbonate resin having a molecular weight of 1,000 to 250,000. (2) The heat-sensitive transfer layer is a heat-sensitive sublimation transfer layer comprising a heat-transferable dye and a binder resin.
The thermal transfer sheet described in section 1). (3) The heat-sensitive transfer sheet according to claim (1), wherein the heat-sensitive transfer layer is a heat-sensitive melting transfer layer comprising a dye or pigment and wax. (4) The heat-sensitive transfer sheet according to claim (1), wherein the polycarbonate resin is represented by the following formula. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (n represents 400 to 1000.)