JPH01176593A - Thermal transfer sheet - Google Patents

Abstract

PURPOSE:To form a recording image having high density and various excellent fastnesses even when heat energy is applied for a short time, by containing a specific dye in the dye support layer formed on one surface of a base sheet. CONSTITUTION:A dye contained in a dye support layer is represented by formula [I] [wherein R1 is CONHR, CONRR', NHCOR, SO2NHR or NHSO2R, T2 and R3 are a halogen atom, an alkyl group, a cycloalkyl group, an alkoxy group, an acylamino group, an aminocarbonyl group, an alkylaryl group or an aryl group, R4 and R5 are an alkyl group which may have a substitutent, an aralkyl group, an aryl group or a hydrogen atom and A is deficiint (in this case, the ring having R1 is represented by formula II) or an atomic group constituting a naphthalene ring (in this case, the ring having R1 is represented by formula III) and R6 is a hydrogen atom or the substituents as mentioned above]. The dye represented by the formula I is obtained by the coupling of p-phenylenediamine compound with phenol or naphthol.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a thermal transfer sheet, and more specifically, provides a thermal transfer sheet that can easily provide a recorded image with excellent fastness to a transfer material. The purpose is to

(Prior art) Various thermal transfer methods have been known in the past, but among them, sublimation dye is used as a recording agent, this is supported on a base sheet such as paper to form a thermal transfer sheet, and dyed with sublimation dye. The thermal transfer sheet is layered on a transferable material such as polyester woven cloth, and thermal energy is applied in a pattern from the back side of the thermal transfer sheet.
A sublimation transfer method is used in which a sublimable dye is transferred to a transfer material.

(Problems to be Solved by the Invention) In the above-mentioned sublimation printing method, in which the material to be transferred is, for example, a polyester woven fabric, heat energy is applied for a relatively long time, so the material to be transferred is As a result, relatively good dye migration is achieved as a result of the heat applied to the dye.

However, with advances in recording methods, it is now possible to print delicate characters and other images onto these materials, such as polyester sheets or paper with a dye-receiving layer, at high speed using a thermal head or the like. When forming graphics or photographic images, it is necessary to apply thermal energy in an extremely short period of seconds or less. Therefore, in such a short period of time, the sublimable dye and the transfer material are not sufficiently Since it is not heated, it is not possible to form an image with sufficient density.

Therefore, in order to cope with such high-speed recording, sublimable dyes with excellent sublimation properties were developed, but dyes with excellent sublimation properties generally have small molecular weights, so they do not dissolve in the transferred material after transfer. Problems arise in that the dye migrates over time or bleeds onto the surface, resulting in problems such as the well-formed image becoming distorted or unclear, or contaminating 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 poor in the high-speed recording method described above, so it will not be possible to form an image with a satisfactory density as described above. It was something.

Therefore, in thermal transfer methods using sublimable dyes,
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 inventor of the present invention discovered that in the conventional sublimation printing method for polyester woven fabrics, etc., the surface of the woven fabric is not smooth, so the thermal transfer sheet and the transfer material cannot be used. Some woven fabrics do not adhere sufficiently, so the dye used must be sublimable or vaporizable (i.e., capable of moving through the space between the thermal transfer sheet and the woven fabric). However, when the transfer material is a polynisdel sheet with a smooth surface or surface-treated paper, etc., the thermal transfer sheet and the transfer material come into close contact during thermal transfer, so the sublimation and vaporization of the dye are reduced. However, the ability of the dye to migrate through the interface between the two when they are in close contact with each other by heat is also extremely important. Knowing that it is greatly influenced by its location,
By selecting a dye with an appropriate molecular structure,
It has been discovered that even dyes with high molecular weights, which are considered unusable according to conventional wisdom, have good thermal transferability. By using a thermal transfer sheet that supports such dyes, the dyes used can be easily transferred to the transfer material even when thermal energy is applied for an extremely short period of time, resulting in high density and excellent fastness. The present invention was completed by discovering that a recorded image having the following characteristics can be formed.

(Means for Solving the Problems) That is, the present invention comprises a base sheet and a dye-carrying layer formed on one side of the base sheet, and the dye contained in the dye-carrying layer is as follows. - A thermal transfer sheet characterized by being a dye represented by formula (I).

However, R1 in the above formula is CONHR, CONRR', N
HCOR1SO□NHR, NH302R (R, R' is an alkyl group optionally substituted with a hydrogen atom or a fluorine atom,
represents a cycloalkyl group or an aryl group which may have a substituent), and R2 and R3 are a halogen atom, an alkyl group, a cycloalkyl group, an alkoxy group, an acylamino group, an aminocarbonyl group, an alkylaryl group, or an aryl group. R4 and R5 represent an alkyl group, an aralkyl group, an aryl group, or a hydrogen atom which may have a substituent, and A is nothing (in this case, the ring with R7 is 6 or the above) represents an atomic group constituting a naphthalene ring which may have a substituent as described above (in this case, the ring having R1 represents a substituent as described above).

(Function) As a result of continuing detailed research on the suitability of various dyes as dyes for thermal transfer sheets, the present inventor found that only the dyes represented by the above general formula (I) have a molecular weight of Even if it is relatively large, it has excellent heat migration properties, and also exhibits excellent dyeing and coloring properties on the transferred material, and also has low dye transferability (bleeding property) in the transferred material. It was discovered that this dye has extremely ideal properties as a dye for thermal transfer sheets.

(Preferred Embodiment) Next, to explain the present invention in more detail, the dye represented by the general formula (I) that mainly characterizes the present invention is a conventionally known dye consisting of a p-phenylenediamine compound and a phenol or a naphthol. It is obtained by the coupling method of

In the present invention, the preferred dye of general formula (I) is A
If there is no NHCOR with R1 in position 1
When the dye group (R is as defined above) and A together constitute a naphthalene ring, R1 is a CONHR or CONRR' (R and R' are as defined above) group in the 1 position. Dyes, particularly preferred are dyes in which R4 and/or R5 in the above preferred dyes are C2 to C2.
8° alkyl group, and at least one of R4 and R5 has a polar group such as a hydroxyl group or a substituted hydroxyl group, an amino group or a substituted amino group, a cyano group, etc., giving the best results, i.e., excellent thermal properties. It had excellent transferability, dyeability to the transferred material, heat resistance during transfer, color development, and excellent transferability after transfer.

Specific examples of dyes suitable for the present invention are listed below. Table 1 below shows substituents R7 to R5 in general formula (I).

A'' 1 - x individuals - RI R, RR, R, - (1) When A constitutes a naphthalene ring and R2 is in the 1 position (R6-H).

I C0NIIC:+FL7CH3CH3C2■s
C2H52C0N)lc3)17 CH3(:)
I3C, H5C2H40H3[;0N)IC3H7CH
3Cl C2)15C2H40H4C0NHC4
H9CI CH3C2H4OHC2H,.

5 (:0NHCsH++ OCH3QG)13
C2H4OHC2H40)+6 C0NHph
OCH3 to H3 (:H3CH37C0NHC2H5C
H30CH3G31117 C8H178C0NH(
:3H70C2H5O(:2H5G2115 C2
84CN9 (:0NHCTo C2H6CzHs
(:2H5CJaOtllo (:0NHC2
1 (S 0C3H70C3H7CJs C2H4
0H11NHCOC3H7C2H50(:2H5C2H
4OHC2) I512 N) IGO, H90C2H
5CI C2H, OHC2H513So, NHC
4H, CH3CH3C4H9C4H914 5O2NH
ph CH3CH3C2H5C2H4CN15 N
H302C3H7CH3(]CH3C2H5C2114
0H16C0NHC3F? oct-+30H302
)15C2H40H18C0NHC2H5CH3C11
3C2)15ph(2)A constitutes a naphthalene ring, R
If 3 is in position 2 < +16=H).

19 C0N11C3H70CH3QC)13CJs
C3H728NHCOC)I3CH3CH3C2
H5C2H40H (3) When A is empty and R1 is in position 1 (R6-11).

2] C0NHC4H8CH3CI+3c2++5C
284ON22 NIIGOCI+30C1130C
I+, C2115C2114CN23 5O2N
HCll+ CI C113C211408C
211401124NHCOC3F7 0C2HS
OC2H5C2H5C2HaOH25N11COC3F
7 C113CH3C2H4OHC2H40H26N
HCOtl:211. B CH3C113C2Hs
CH2ph (4) A or nothing, and if it is in position 11 or 2 (R6 H).

27 C0NIICH3CH3CH3C31b
C3H728NHCOC2H5QC3H,QC3H,C
2H3c2++4o++29 NHCOC3F7QC
2H5Br C2115C21LOII(5)A
constitutes a naphthalene ring, R6 is in the 1 position, and R6
If is not a hydrogen atom.

(6) When A is absent, R1 is in position 1, and R6 is not a hydrogen atom.

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

The base sheet used for constructing the thermal transfer sheet of the present invention containing the above-mentioned dye may be any conventionally known material having a certain degree of heat resistance and strength, for example, 0.5 to 50 μm, Preferably, paper with a thickness of about 3 to 10 μm, various processed papers, polyester film, polystyrene film, polypropylene film, polysulfone film, polycarbonate film, aramid film, polyvinyl alcohol film, cellophane, etc. are used, and particularly preferred is polyester film. be.

The dye-carrying layer provided on the surface of the base sheet as described above is a layer in which the dye of general formula (I) is supported by any binder resin.

As the binder resin that supports the above-mentioned dye,
Any conventionally known ones can be used, and preferred examples include cellulose resins such as ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxy cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, and cellulose acetate butyrate, polyvinyl alcohol, and polyvinyl acetate. , polyvinyl butyral, polyvinyl acetal, polyvinyl pyrrolidone, polyacrylamide, and other vinyl resins. Among these, polyvinyl butyral and polyvinyl acetal are particularly preferred from the viewpoint of heat resistance, dye migration, and the like.

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-supporting layer is preferably prepared by adding the dye, binder resin, and other optional components in a suitable solvent, dissolving or dispersing each component, and preparing a coating solution or ink for forming the dye-supporting layer. It is formed by coating and drying on the above base sheet.

The support layer formed in this way has a thickness of 0.2 to 5.0 μm.
m preferably has a thickness of about 0.4 to 2.0 μm,
Further, the above-mentioned dye in the support layer is contained in an amount of 5 to 70% of the weight of the support layer.
It is suitably present in an amount of 10% to 60% by weight.

The thermal transfer sheet of the present invention as described above is fully useful for thermal transfer as it is, but it is also possible to provide an anti-adhesive layer, that is, a release layer, on the surface of the dye-carrying layer. This prevents adhesion between the thermal transfer sheet and the transfer material during thermal transfer, allows use of a higher thermal transfer temperature, and forms an image with excellent density.

As this mold release layer, it is quite effective to simply apply an inorganic powder with anti-adhesive properties, 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 μm, preferably 0.05 to 2 μm.

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

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

The transfer material used to form an image using the thermal transfer sheet as described above 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. that does not have any properties, a dye-receiving layer may be formed on at least one surface thereof.

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

Particularly preferred are sheets or films made of polyester, or treated paper provided with a polyester layer. In addition, even if the transfer material is non-dyeable such as paper, metal, glass, etc., a solution or dispersion of a dyeable resin such as those mentioned above is coated on the recording surface and dried, or the resin is By laminating the film, it can be used as a transfer material.

Furthermore, even if the transfer material has the dyeability 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 formed in this manner may be formed from a single material or from a plurality of materials, and may also contain various additives as long as the intended purpose is not hindered. Of course.

Such a dye-receiving layer may be of any thickness, but radiationally has a thickness of 5 to 50 .mu.m. 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 a transfer material is basically as described above and can be used as is, but it is possible to incorporate an inorganic powder for preventing adhesion into the transfer 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 material to be transferred can be prevented, and even better thermal transfer can be performed. Particularly preferred is finely powdered silica.

Further, in place of or in combination with the above-mentioned 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 a release agent may be used 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 transfer 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 having excellent mold release properties as described above may be used. A layer consisting of may be provided.

Such a release layer exhibits a sufficient effect at a thickness of about 0.01 to 5 μm, and can prevent adhesion to the dye-receiving layer of the thermal transfer sheet and improve the dye-receptivity of the layer.

As the means for applying thermal energy used when performing thermal transfer using the thermal transfer sheet of the present invention as described above and the recording material as described above, any conventionally known applying means can be used.
For example, by controlling the recording time using a recording device such as a thermal printer (for example, Video Printer VY-100 manufactured by Hitachi), it is possible to
By applying thermal energy of approximately J/mrn'', the intended purpose can be fully achieved.

(Effects) According to the present invention as described above, as already partially explained, the above-mentioned formula (
Although the dye I) has a significantly higher molecular weight than the sublimable dyes (molecular weight approximately 150 to 250) used in conventional thermal transfer sheets, it has a specific structure, and Because it has a substituent at a specific position, it exhibits excellent heat transferability, dyeing and coloring properties on the transferred material, and after transfer, it does not migrate into the transferred material or bleed out onto the surface. It is something that does not happen.

Therefore, since images formed using the thermal transfer sheet of the present invention have excellent fastness, especially migration resistance and stain resistance, the sharpness of the formed images will not be impaired even after long-term storage. Also, there is no contamination of other articles, and various problems of the prior art have been solved.

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

Example 1 2.29 parts of a compound represented by the following structural formula was added to 200 parts of 95% ethanol.
An aqueous solution prepared by dissolving 5 parts of anhydrous sodium carbonate in 50 parts of water was added to the resulting solution to prepare a mixed solution.

Next, 2.48 parts of the compound represented by the following structural formula was dissolved in 50 parts of water, and the resulting solution was added to the above-mentioned mixture, and after thorough stirring, 1
Gradually add 100 parts of a 1.6% potassium ferrocyanide aqueous solution, stir in this state for 15 minutes, filter, and wash with pure water. When the filtrate becomes neutral, it is dried, the product is dissolved in ethyl acetate, and a special column is prepared using ethyl acetate/heptane to obtain a dye with the following structural formula [dye No. 1 in Table 1 above]. I got it.

Example 2 The dyes listed in Table 1 above were obtained in the same manner as in Example 1, except for using different raw materials.

Example 3 An ink composition for forming a dye-carrying layer having the following composition was prepared and applied to a polyethylene terephthalate film with a thickness of 4 to 5 μm that had undergone heat-resistant treatment on the back side so that the dry coating amount was 1.0 g/m''. and dried to obtain a thermal transfer sheet of the present invention.

Dyes of Table 1 3 parts Polyvinyl acetoacetal resin 4.5 parts Methyl ethyl ketone 46.25 parts Toluene
46.25 copies Next, synthetic paper (
Using Yubo FPG #150 (manufactured by Tamago Yuka Co., Ltd.), a coating solution with the following composition was applied to one side at a rate of 10.0 g/m'' when dry, and dried at 100°C for 30 minutes. A transfer material was obtained.

Polyester resin (Vylon200, manufactured by Toyobo) 11
．． 5 parts vinyl chloride-vinyl acetate copolymer (VY) I, U
(: Made by C) 5. Part o amino-modified silicone (KF-393, +=manufactured by Etsu Kagaku Kogyo) 1.2 parts epoxy-modified silicone (X-22-343, I8 Manufactured by Etsu Kagaku Kogyo)
1.2 parts methyl ethyl ketone/toluene/cyclohexanone (weight ratio 4:4:2
) 102.0 parts The thermal transfer sheet of the present invention and the transfer material described above are stacked one on top of the other with their respective dye-carrying layers and dye-receiving surfaces facing each other, and a head voltage of 10 V is applied from the back side of the thermal transfer sheet for a printing time. 4,0 m5ec
- Recording was performed with a thermal head under the following conditions, and the results shown in Table 2 below were obtained.

Comparative Example The dyes shown in Table 3 below were used as the dyes in Example 3, and the other conditions were the same as in Example 4 to obtain the results shown in Table 3 below.

However, the composition of the ink composition for forming the dye-carrying layer was as follows.

Dyes in Table 3 below 3 parts Polyvinyl acetoacetal resin 4.5 parts Methyl ethyl ketone 46.25 parts Toluene
4625 parts ~ 2 2: F -64+'+; -11,
00◎ Before yellow 417 2 095 ◎ Before yellow 4333
0.97 ◎ Before yellow 42554 0
．． 82 ◎ Before yellow 487,55 0
．． 84 ◎ Before yellow 4616 0.9
2 ◎ Before yellow 4397 038
◎ Before yellow 5878 0.69 ◎
Before yellow 5029 095 ◎ Before yellow
43310 0.67 ◎ Before yellow 5
0711 0.78 ◎ Before yellow 47
712 0.71 ◎ Before yellow 497
．． 5+3 0.52 ◎ Before yellow 52
3. ]14 0, [i6 ◎ Pre-yellowish
512.115 0.8] ◎ Before yellow 469.116 1.10 0 Before yellow 57517 0.9] ◎
Blue 44218 0.88 ◎
Blue 45119 1.21
0 blue 44920] ,0
5 ◎ Blue 40521
1.31 ◎ Blue 39722
1.29 ◎ Blue 3962
31.20 ◎ Blue 427.62
4 1.47 ◎ Blue 5
6925 1.63 ◎ Blue
5252fi I old ◎
Blue 41527 1.42 ◎
Before redness 36728 1.12 ◎
Before redness 45729 ] , 53 ◎
Before redness 6o3930 0.79
◎ Blue 4753.1 1.00
◎ Blue 41932
0.98 ◎ Blue 42533
1.01 ◎ Blue 4]5.
5. The dyes in the above table are indicated by the numbers in Table 1 above.

Dar 3 − − ゛ P ″′″′ = 1 0.99
x Blue 2116 △ Blue 3 2.07 x Blue 4 1.12 △ Blue 5 1.02 x Purple In addition, the dyes in the above table are as follows.

1・C11, Disbirds Blue 14 2 ClDisbirds Blue 134 3,: C,1, Solvent Blue 634: C,1
, Teaspers Blue 265: C, I Disbirds Violet 4 The coloring densities in Tables 2 and 3 above are values measured with a densitometer RD-918 manufactured by Macbeth, USA.

Fastness is ◎ 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. If the image is lost and the white paper is slightly colored, it is rated O. If the sharpness is lost and the white paper is colored, it is △. If the image is unclear and the white paper is markedly colored, it is rated ×.
It was displayed in

Patent applicant: Dainichi Printing Co., Ltd., Mi agent: Patent attorney Yoshi 1) Katsuhiro, ′-2′, ゛・
So, -

Claims (4)

[Claims] (1) Consists of a base sheet and a dye-supporting layer formed on one side of the base sheet, and the dye included in the dye-supporting layer is a dye represented by the following general formula (I). A thermal transfer sheet featuring ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) [However, R_1 in the above formula is CONHR, CONRR'
, NHCOR, SO_2NHR, NHSO_2R(R,
R' represents an alkyl group whose hydrogen atom may be substituted with a fluorine atom, a cycloalkyl group, or an aryl group which may have a substituent), and R_2 and R_3 represent a halogen atom, an alkyl group, a cyclo represents an alkyl group, an alkoxy group, an acylamino group, an aminocarbonyl group, an alkylaryl group, or an aryl group, R_4 and R_5 represent an alkyl group, an aralkyl group, an aryl group, or a hydrogen atom that may have a substituent; It represents an atomic group constituting a naphthalene ring as a whole, which may have no substituent or a substituent as described above. ] (2) The thermal transfer sheet according to claim (1), wherein when A is absent, R_1 is an NHCOR (R is as defined above) group present at the 1 position. (3) When A constitutes a naphthalene ring as a whole, R_1
CONHR or CONRR'(R
, R' is a group (as defined above).
The thermal transfer sheet described in item 1). (4) The thermal transfer sheet according to claim (1), wherein R_4 and/or R_5 is an alkyl group having a polar group.