JPS61268495A - Thermal transfer sheet - Google Patents

Abstract

PURPOSE:To raise various fastnesses of recorded pictures by using a thermal transfer sheet having a dye-supporting layer containing a sublimable dye with 5 or more ring structures in its molecule, having a molecular of 350 or more, on one side of its base sheet. CONSTITUTION:A sublimable dye of 350 or more molecular weights, having at least 5 ring structures in its molecule, is dissolved or dispersed in a binder resin to prepare a coating liquid for forming a supporting layer. The coating liquid is applied on a base sheet and dried to form a thermal transfer sheet with the dye-supporting layer. The sublimable dye, as represented by the formulas I and II, is contained in an amount of 5-70wt%, preferably 10-60wt%, in the dye-supporting layer. The preferred thickness of the dye-supporting layer is 0.2-5.0mum, more preferably 0.4-2.0mum. As the base sheet, finished yarns, synthetic resin films, etc., having 5-50mum thickness are used.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a thermal transfer sheet, and more specifically, provides a novel thermal transfer sheet that can easily provide a recorded image with excellent fastness on a recording material. The purpose is to

(Prior art) Various thermal transfer methods have been known in the past, but among them, a thermal transfer sheet is prepared by using a sublimation dye as a recording agent, supported on a base sheet such as paper, and using a sublimation dye as a recording agent. A sublimation transfer method is performed in which a dyeable recording material, such as a polyester sheet or a polyester woven cloth, is layered and thermal energy is applied in a pattern from the back side of the thermal transfer sheet to transfer the sublimable dye to the recording material. It is being said.

(The point that the invention is trying to solve) In the sublimation printing method in which the recording material is, for example, polyester woven cloth, etc., the recording material is As a result of the fact that the dye itself is heated by the applied thermal energy, relatively good dye migration is achieved.

However, with advances in recording methods, thermal heads and the like have been used to record images at high speed, such as on polyester sheets.
When forming delicate characters, figures, or photographic images on recording materials using paper with a dye-receiving layer, the application of thermal energy is extremely short, on the order of seconds or less. Therefore, in such a short time, the sublimable dye and the recording material are not sufficiently heated, making it impossible to form an image with sufficient density.

Therefore, in order to cope with such high-speed recording, four-color dyes with excellent sublimation properties were developed.However, dyes with excellent sublimation properties generally have small molecular weights, so they cannot be used on the recording material after transfer. Problems have arisen in that the dye migrates over time or bleeds onto the surface, causing the well-formed image to become distorted or unclear, or to contaminate surrounding articles.

In order to avoid such problems, if a sublimable dye with a relatively large molecular weight is used, the sublimation speed will be inferior in the high-speed recording method as described above, so it will not be possible to form an image with a satisfactory density as described above. Met.

Therefore, in thermal transfer methods using sublimable dyes,
There is a strong demand for the development of a thermal transfer sheet that can produce sufficiently dense and clear images by applying thermal energy in an extremely short period of time, such as two feet, and that also exhibits excellent fastness. The current situation is that

The inventor of the present invention] - As a result of intensive research in response to the strong demands of the industry as described above, by using a thermal transfer sheet that uses a sublimable dye with a specific structure, it is possible to apply heat energy for an extremely short period of time. The present invention was completed based on the finding that the sublimable dye used easily migrates to the recording material, forming recorded images with high density and excellent fastness.

(Means for Solving the Problems) That is, the present invention comprises a base sheet and a dye-carrying layer provided on one surface of the base sheet, and the dye contained in the dye-carrying layer is at least 350%. This thermal transfer sheet is characterized by being a sublimable dye having a molecular weight as follows and having at least 5 ring structures in the molecule.

Next, to explain the present invention in more detail, the dye as defined above used in the present invention and which mainly characterizes the present invention itself is a known dye, and has conventionally been used mainly as a disperse dye for polyester fibers and the like. be.

Conventionally, various disperse dyes have been used as dyes for the sublimation transfer method, but because the sublimation transfer method requires a rapid sublimation rate, they are generally limited to those with a molecular weight of about 300 or less, and they are made with as few polar groups as possible. Those that do not have have been selected and used.

However, as mentioned above, such materials with relatively low molecular weight and no polar groups have good transfer speed and color development, but as mentioned above, they produce images with low migration resistance and stain resistance. It was worth 4 years.

As a result of detailed research into the suitability of known disperse dyes for thermal transfer, which had previously been completely excluded from use in sublimation transfer methods, the present inventor found that even if the molecular weight exceeds 350, Only those that have at least 5 ring structures in the molecule have excellent heat sublimation properties that are unimaginable from conventional wisdom, and also have excellent dyeing and coloring properties on the base sheet. Furthermore, it was found that there was no dye migration (bleeding) or staining in the transferred recording material, and that the dye had extremely ideal properties as a dye for thermal transfer sheets.

Particularly suitable dyes as defined above for use in the present invention include those having the following structure.

028818N204 (MW=422.4) (blank below) 028H22N202 (MW=418.5) 028H22N202 (MW=418.5) C24H18C24H 18N202C34H 34N204(,462) (MW=1(88,13) C41H32 N404 (MW=844. 7) (Hereinafter in the margin) 0291124NB (MW=458.ll)'' - Particularly preferred dyes among the exemplified dyes 1 and other dyes that can be used in the present invention have a molecular weight of about 35.
0 to 700. If the molecular weight is less than 350, the various drawbacks of the prior art cannot be satisfactorily solved, and if the molecular weight exceeds 700, the thermal transfer speed and color development will be poor, which is not preferred.

The thermal transfer sheet of the present invention is characterized by using the above-mentioned specific sublimable dye, and other than that, the structure may be the same as that of conventionally known thermal transfer sheets.

The base material sheet used in the construction of the thermal transfer sheet of the present invention may be any conventionally known material having a certain degree of heat resistance and strength, for example, 0.5 to 50 #
Lm, preferably paper with a thickness of about 3 to 10 gm, various processed papers, polyester film, polystyrene film,
Polypropylene film, polysulfone film, polycarbonate film, and polyvinyl alcohol film are polyester films.

The dye-supporting layer provided on the surface of the base sheet as described above is a layer in which the above-mentioned sublimable dye is supported by an arbitrary binder resin.

As the binder resin for supporting the above sublimable dye, any conventionally known binder resin can be used, and preferred examples include ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxy cellulose, hydroxyprol cellulose, methyl cellulose, Cellulose resins such as cellulose acetate and cellulose acetate butyrate, vinyl resins such as polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinylpyrrolidone, and polyacrylamide, polyesters, etc. are preferred from the viewpoint of heat resistance, dye migration, etc. It is.

The dye-carrying layer of the thermal transfer sheet of the present invention is basically formed from the above-mentioned materials, but may also contain various conventionally known additives as required.

Such a dye-carrying layer is preferably prepared by adding the above-mentioned sublimable dye, binder resin, and other optional components to a suitable solvent and dissolving or dispersing each component to prepare a coating liquid or ink for forming a compatible layer. This is formed by coating and drying the above base sheet.

The compatible layer formed in this way is 0.2 to 5.0 JLm.
, preferably has a thickness of about 0.4 to 2.07 zm,
The sublimable dye in the supporting layer is 5 to 70% of the weight of the supporting layer.
It is suitably present in an amount of 10% to 60% by weight.

The thermal transfer sheet as described above is fully useful in the present invention as it is, but it may also be provided with an anti-adhesive layer, that is, a release layer, on the surface of the dye-carrying layer. It is possible to prevent adhesion between the thermal transfer sheet and the recording material at times, use a higher thermal transfer temperature, and form images with even better density.

As this mold release layer, even if an inorganic powder with anti-adhesive property is simply adhered, it has a considerable effect, and it is also possible to use resins with excellent mold release properties such as silicone polymers, acrylic polymers, and fluorinated polymers. It can be formed by providing a release layer of 0.01 to 5 ILm, preferably 0.05 to 2 pm.

Incidentally, the above-mentioned inorganic powder or releasable polymer exhibits a sufficient effect even when included in the dye-carrying layer.

Furthermore, a heat-resistant layer may be provided on the back surface of such a thermal transfer sheet of the present invention in order to prevent adverse effects caused by the heat of the thermal head.

The recording material used to form an image using the thermal transfer sheet of the present invention may be any material as long as its recording surface has dye receptivity to the above-mentioned dyes. If the material is paper, metal, glass, synthetic resin, etc., which does not have a dye, a dye-receiving layer may be formed on at least one surface thereof.

Examples of recording materials that do not require the formation of a dye-receiving layer include polyolefin resins such as polyethylene and polypropylene, halogenated polymers such as polyvinyl chloride and polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetate, and polyacrylic ester. vinyl polymers such as polyethylene terephthalate, polyester resins such as polybutylene terephthalate, polystyrene resins, polyamide resins, copolymer resins of olefins such as ethylene and propylene with other vinyl monomers, ionomers,
Examples include fibers, woven fabrics, films, sheets, and molded products made of cellulose resins such as cellulose diacetate and cellulose triacetate, polycarbonate, polysulfone, and polyimide.

Particularly preferred are woven fabrics, sheets or films made of polyethylene terephthalate.

In addition, in the present invention, even if the recording material is non-stainable such as paper, metal, glass, etc., a solution or dispersion of a dyeable resin as described above is coated on the recording surface and dried. ,
Alternatively, by laminating these resin films, it can be used as a recording material.

Furthermore, even if the recording material is dyeable as described above, a dye-receiving layer may be formed on the surface thereof from a resin having better dyeability, as in the case of the paper described above.

The dye-receiving layer thus formed may be formed from a single material or from a plurality of materials, and may also contain various additives as long as the object of the present invention is not hindered. Of course.

Such dye-receiving layers may be of any thickness, but are typically between 5 and 50 pLm thick. Although such a dye-receiving layer is preferably a continuous coating, it may also be formed as a discontinuous coating using a resin emulsion or resin dispersion.

Such recording materials are basically as described above and can be used as they are, but it is possible to incorporate an inorganic powder to prevent adhesion into the -F liquid distribution recording material or its dye-receiving portion. In this way, even if the temperature during thermal transfer is increased, adhesion between the thermal transfer sheet and the recording material can be prevented, and even better thermal transfer can be performed. Particularly preferred is finely powdered silica.

Furthermore, in place of or in combination with the inorganic powder such as silica, the above-mentioned resin having good mold releasability may be added. Particularly preferred release polymers include cured products of silicone compounds, such as cured products of epoxy-modified silicone oil and amino-modified silicone oil.

Such release agents may be present in an amount of about 0.5 to 3 by weight of the dye-receiving layer.
A ratio of 0% by weight is good.

The recording material used may have an inorganic powder as described above adhered to the surface of the dye-receiving layer to enhance the anti-adhesive effect, or a mold release agent with excellent mold release properties as described above may be used. A layer consisting of may be provided.

Such a release layer has a thickness of about 0. A sufficient effect can be exhibited with a thickness of 01 to 5 JLm, and the dye receptivity can be further improved while preventing adhesion to the dye receptive layer of the thermal transfer sheet.

Any conventionally known means for imparting thermal energy can be used to apply thermal energy when performing thermal transfer using the thermal transfer sheet of the present invention and the recording material as described above, such as a thermal printer (for example, Toshiba By controlling the recording time using a recording device such as a thermal printer TN-5400 manufactured by
/m by imparting thermal energy of degree,
The purpose of the present invention can be fully achieved.

(Function/Effect) According to the present invention as described above, as already partially described, the specific dye used in the composition of the thermal transfer sheet of the present invention is a sublimable dye (molecular weight Although it has a significantly higher molecular weight of 350 or more compared to
Because it has a ring structure of Never.

Therefore, images formed using the thermal transfer sheet of the present invention have excellent fastness, especially migration resistance and stain resistance, so that even if stored for a long period of time, the sharpness of the formed image may be impaired or other defects may occur. The various problems of the prior art have been satisfactorily solved without contaminating the articles.

This previously unimaginable excellent effect appears particularly when the dye-receiving portion of the recording material is made of a material such as polyester, because the dye used in the present invention has a large number of rings as a whole molecule. Because it has a structure, it is thought that it is fixed in the polyester by some action due to the correlation with the aromatic ring in the polyester.

Next, the present invention will be explained in more detail with reference to Examples. In addition, parts and percentages in the text are based on weight unless otherwise specified.

Examples 1 to 8 An ink composition for forming a dye-carrying layer having the following composition was prepared and applied to a 9 gm thick polyethylene terephthalate film whose back surface had been heat-resistant treated so that the dry coating amount was 1.0 g/m''. and dried to obtain a thermal transfer sheet of the present invention.

Dyes listed in Table 1 below 3 parts Polybutyral resin 4.5 parts Methyl ethyl ketone 46.25 parts Toluene
46.25 copies Next, a synthetic paper (Yubo FPG# 150, manufactured by Tamago Yuka Co., Ltd.) was used as a base sheet, and a coating liquid with the following composition was applied to one side of the paper to give a dry weight of 4.5 g/m''. A recording material was obtained by applying the mixture at the same ratio and drying at 100° C. for a minute.

Polyester resin (Vylon103, manufactured by Toyobo, Tg = 47°C) 0
．． 8 parts EVA polymer plasticizer (Elvaloy 741P, manufactured by Mitsui Polychem Manufacturer, Tg=-
37°C) 0.2 part Amino-modified silicone (KF-857, manufactured by Shin-Etsu Chemical) 0.04 part Epoxy-modified silicone (KF-103, manufactured by Shin-Etsu Chemical) 0.04 part Methyl ethyl ketone/toluene/cyclohexane (by weight ratio 4
:4:2) 9, 0 parts The thermal transfer sheet of the present invention and the recording material described above are placed one on top of the other with their respective dye-carrying layers and dye-receiving surfaces facing each other, and a head applied voltage is applied from the back side of the thermal transfer sheet. 10V, printing time 4.
Recording was performed with a thermal head under the condition of 0 asec, and the results shown in Table 1 below were obtained.

u I II III ■l
M[1,010,910,1110,281''2L
OOO0 Color - 112 tone Purple Purple Green
Red 5 6 7 Base dyeing --- fee V VI
■ ■Intermediate A11L degree 0.40
0.4B 1.12 0.88 hard-” once ooo.

Color - One tone Green Yellow Red
Note that Dye I is a dye of the above formula (a).

Dye II is the dye of formula (b) above.

Dye Ne 4■ is a dye of the above formula (C).

Dye (3) is a dye of formula (d) above.

Dye V is a dye of formula (e) above.

Dye (3) is a dye of formula (f) above.

Dye (3) is a dye of formula (g) above.

Dye (3) is a dye of formula (h) above.

Comparative Examples 1 to 7 The dyes shown in Table 2 below were used as the dyes in Examples 1 to 5, and the other conditions were the same as in Example 1 to obtain the results shown in Table 2 below.

Dye-J I'II' III
'IV' degree 1.76 0
．． 8B 1.03 0.40 solid once
Δ Δ × Δtemporary−−1
Red Purple Blue Purple Purple j μ l u V′ Vl′ ■′Eya l[1,1
20,880,57 uX Δ Δ Color-111 Tsuba Yellow Yellow
Indigo Dye 1' is Disbird's Red L.

Dye ■' is Disbird's Violet I.

The dye m' is Disbirds φ Violet 4.

Dye ■' is Disbird's Violet 28.

Dye V' is Disverse Yellow 7.

Dye ■' is Disbird's Yellow 23.

Dye ■' is Disverse Blue 26.

The coloring densities in Tables 1 and 2 are values measured using Tensheet Meter HD-918 manufactured by Macbeth, USA.

Fastness is defined as 0 if the sharpness of the image does not change after the recorded image is left in an atmosphere at 50°C for a long time, and the white paper does not become colored even when the surface is rubbed with white paper. A case where the white paper became colored was indicated as Δ, and a case where the image became unclear and the white paper was markedly colored was indicated as ×.

Patent applicant: Dai Nippon Printing Co., Ltd. Procedural layer l (voluntary) June 17, 1985

Claims (2)

[Claims] (1) Consists of a base sheet and a dye-carrying layer provided on one side of the base sheet, and the dye contained in the dye-carrying layer has a molecular weight of at least 350 and at least 5 dyes in the molecule. A thermal transfer sheet characterized by being a sublimable dye having a ring structure. (2) The thermal transfer sheet according to claim (1), wherein the dye has a molecular weight of 350 to 700.