JPS61268494A - Thermal transfer sheet - Google Patents

Abstract

PURPOSE:To raise various fastnesses of recorded pictures by providing a dye- supporting layer containing a sublimable dye of a molecular weight of 350 or more, having nitro, cyano, or sulfonyl group in its molecule, on one side of a base sheet. CONSTITUTION:A sublimable dye of a molecular weight of 350 or more, having at lest one of nitro, cyano, and sulfonyl group in its molecule, is dissolved or dispersed in a binder resin to prepare a coating liquid for forming a spporting layer. The coating liquid is applied on a base sheet and dried to form a thermal transfer sheet with a 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. A releasing layer may be further provided on the dye-supporting layer.

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 sublimation dye is used as a recording agent, this is carried on a base sheet such as paper to form a thermal transfer sheet, and the dye is dyed with a sublimation dye. A sublimation transfer method is used in which the sublimable dye is transferred to the recording material by applying thermal energy in a pattern from the back side of the thermal transfer sheet to a printable recording material such as a polyester sheet or polyester woven cloth. ing.

(Problem to be Solved by the Invention) In the A flower transfer method described above, in the sublimation printing method in which the recording material is, for example, polyester woven cloth, the application of thermal energy is relatively long, so the recording material 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, A-flowering dyes with excellent sublimation properties were developed, but dyes with excellent A-flowering properties generally have small molecular weights, so they do not easily absorb the recorded material after transfer. Problems arise in that the dye migrates in the material 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 high molecular weight is used, the sublimation speed is inferior in the high-speed recording method described above, so it is impossible to form an image with a satisfactory density as described above. Met.

Therefore, in the thermal transfer method using A flower dye,
At present, there is a strong demand for the development of a thermal transfer sheet that can provide sufficiently dense and clear images by applying thermal energy in an extremely short period of time as described above, and also exhibits excellent fastness of the formed images. It is.

As a result of intensive research in response to the strong demands of the industry as described above, the inventors of the present invention have developed a thermal transfer sheet that uses A-color dye with a specific structure, which enables the application of thermal 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 properties.

(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%. The present invention is a thermal transfer sheet characterized by being a sublimable dye having a molecular weight of at least one of the following and having at least one nitro group, cyano group, or sulfonyl group 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 A blooming rate, they are generally limited to those with a molecular weight of about 300 or less, and are preferably made with polar groups. Those without have been used selectively.

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 something to give.

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 one specific polar group, ie, nitro group, cyano group, or sulfonyl group (or a linking group) in the molecule, have excellent thermal sublimation properties that are unimaginable from conventional wisdom. have,
Furthermore, it exhibits excellent dyeing and coloring properties on the base sheet,
Moreover, there was no migration (bleeding) or staining of the dye in the transferred recording material, and it was found that the dye has 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.

C4)19 Among the above-exemplified dyes and non-exemplified dyes that can be used in the present invention, particularly preferred ones have a molecular weight of about 350 to
700. For those with a molecular weight of less than 350,
Various drawbacks of the prior art have not been fully resolved, and 70
If the molecular weight exceeds 0, the thermal transfer speed and color development will be poor, which is not preferable.

Also, particularly preferred is a dye having a nitro group.

It has two or more of a cyano group and a sulfonyl group, and these things are more effective in achieving the object of the present invention, that is, excellent migration resistance and resistance, than those having one group. An image with staining properties can be provided.

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 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 m, preferably 3 to 50 m. Paper with a thickness of about 10ILm, 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 A flower dye is supported with an arbitrary binder resin.

As the binder resin for supporting the above A flower dye, any conventionally known binder resin can be used, and preferred examples include ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxy cellulose, hydroxypropyl cellulose, methyl cellulose, and acetic acid. Cellulose resins such as cellulose 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. be.

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 applying and drying this onto the above-mentioned base sheet.

The supporting layer formed in this way has a weight of 0.2 to 5.0 g.
m, preferably 0.4-2. The thickness is about OpLm, and the A color dye in the support layer is about 5 to 7 times the weight of the support layer.
Suitably it is present in an amount of 0% by weight, preferably 10-60% 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. By using a higher thermal transfer temperature, we can prevent the thermal transfer sheet from sticking to the recording material during printing.
Images with even better density can be formed.

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 gm, preferably 0.05 to 2 #Lm.

Incidentally, even if the inorganic powder or the release polymer as described in -I- is included in the Dyed Nene 4 Compatible Layer, sufficient effects can be obtained.

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-dyeable such as paper, metal, glass, etc., a dyeable resin solution or dispersion as described above is coated on the recording surface and dried, or By laminating these resin films, a recording material can be obtained.

Furthermore, even if the recording material is dyeable as described in (-) 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 a dye-receiving layer may be of any thickness, but is typically between 5 and 50 #Lm thick. Further, although it is preferable that the dye-receiving layer be coated continuously, it may be formed as a discontinuous coating using a resin emulsion or a resin dispersion.

Such a recording material is basically as described above and can be used as is, but it is possible to incorporate an inorganic powder for adhesive soundproofing into the recording material or its dye-receiving layer. 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.

In addition, the recording material to be used may have an inorganic powder as described above attached 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. 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 ILm, and dye receptivity can be further improved while preventing adhesion with the dye receptive layer of the thermal transfer sheet.

Any conventionally known means for applying 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 5 to 100 m J by controlling the recording time using a recording device such as a thermal printer TN-5400 manufactured by
/ By applying thermal energy of about
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 150-300), it has a significantly higher molecular weight of 350 or more.
Because it has nitro groups, cyano groups, or sulfonyl groups, it exhibits excellent heat sublimation properties, dyeing properties on base sheets, and coloring properties. No bleed out.

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.

In particular, in the case of a dye having at least two polar groups as a specific dye, the fastness as described above becomes even more remarkable. 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 many polarities as a whole molecule. Because it has a polar group in the polyester, it is thought that it is fixed in the polyester by some action due to the correlation with a certain ester bond.

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 5 An ink composition for forming a dye-carrying layer having the following composition was prepared, and a dry coating amount of 1.0 g/rn was applied to a 9ILm thick polyethylene terephthalate film whose back side was heat-resistant treated.
The thermal transfer sheet of the present invention was obtained by coating and drying so as to obtain a heat 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 parts Next, using synthetic paper (Yubo FPG #150 manufactured by Tamago Yuka Co., Ltd.) as a base sheet, a coating liquid with the following composition was applied to one side of the paper at a dry rate of 4.5 g/rrf. A recording material was obtained by applying the mixture in the following proportions 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 Polychemicals, Tg==
37°C) 0.2 part Amine-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. Q part The thermal transfer sheet of the present invention described above 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 voltage applied to the head is applied from the back surface of the thermal transfer sheet. tOV, printing time 4
．． Recording was performed with a thermal head under the condition of 0+wsec, and the results shown in Table 1 below were obtained.

J I II m IT V
Menmu11 2.0? 0.513 2.0B
1.11 1.21w o o o
o.

Color - 112 shades Yellow Red Red Indigo Red Note that dye I is the dye of formula (a) above.

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

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

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

Dye $4 V is the dye of formula (i) above.

Comparative Examples 1 to 5 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. .

91-U immun--l bi ■bi n'r'rv' previous color [1,760,8B 1.03 0.40 supervision]
Ll Δ Δ × Δ number--1
Red Purple Blue Purple Purple Rui Dan ヱ1--l V” Vl′ ■′N degree
1.12 0.1li8 0.5
7 solid once × Δ Δ
Color ---- tone Yellow Yellow
Indigo: Dye I' is Disbird's Red I.

Dye II'' is Disverse Violet 1.

Dye ■' is Disbird's Fist Violet 4.

Dye ■' is Disbird's Violet 28.

Dye V' is Disverse Yellow 7.

Dye ■' is Disbird's Yellow 23.

The 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 O 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 was colored was marked as △, and a case where the image became unclear and the white paper was markedly colored was marked as ×.

Patent applicant: Dai Nippon Printing Co., Ltd. (Issuance of procedural amendment) June 17, 1985

Claims (3)

[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 or more, and at least one dye is contained in the molecule. A thermal transfer sheet characterized by being a sublimable dye having a nitro group, a cyano group or a sulfonyl group. (2) The thermal transfer sheet according to claim (1), wherein the dye has a molecular weight of 350 to 700. (3) The thermal transfer sheet according to claim (1), wherein the dye is a dye having at least two of a nitro group, a cyano group, or a sulfonyl group.