JPH0717107B2 - Thermal transfer sheet - Google Patents

Description

TECHNICAL FIELD The present invention relates to a thermal transfer sheet, and more specifically, it provides a novel thermal transfer sheet capable of easily providing a recorded image having excellent fastness to a recording material. The purpose is to

(Prior Art) Conventionally, various thermal transfer methods are known. Among them, a sublimable dye is used as a recording agent, and a sublimable dye is carried on a base material sheet such as paper to form a thermal transfer sheet. A sublimation transfer method is performed in which a sublimable dye is transferred onto a recording material that can be attached, for example, a polyester sheet or a polyester woven cloth, and thermal energy is applied in a pattern from the back surface of the thermal transfer sheet to transfer the sublimable dye to the recording material. ing.

(Problems to be Solved by the Invention) In the sublimation transfer method described above, in the sublimation printing method in which the recording material is, for example, a polyester woven fabric, the recording material itself is applied because heat energy is applied for a relatively long time. Also as a result of being heated with the applied thermal energy, a relatively good dye transfer is achieved.

However, due to advances in recording methods, using a thermal head or the like, at high speed, for example, a polyester sheet,
When using recording materials provided with a dye-receiving layer on paper and forming delicate characters or figures or photographic images on these recording materials, the application of heat energy is extremely short, such as seconds or less. Therefore, since the sublimable dye and the recording material are not sufficiently heated in such a short time, an image having a sufficient density cannot be formed.

Therefore, in order to cope with such high-speed recording, a sublimable dye having excellent sublimation property has been developed. However, since the dye having excellent sublimation property generally has a small molecular weight, it can be recorded in a recording material after transfer. In the above, there is a problem in that the image formed at an angle is disturbed, becomes unclear, or contaminates the surrounding articles due to transition with time or bleeding out on the surface.

If a sublimable dye having a relatively large molecular weight is used in order to avoid such a problem, the sublimation rate is inferior, so that an image having a satisfactory density cannot be formed as described above.

Therefore, in the thermal transfer method using the sublimable dye,
It is currently strongly desired to develop a thermal transfer sheet that gives a clear image with sufficient density by applying heat energy for an extremely short time as described above, and that the formed image shows various fastnesses. Is.

As a result of earnest research to meet the strong demands of the industry as described above, the present inventor uses a thermal transfer sheet using a sublimable dye having a specific structure, so that even when applying thermal energy for an extremely short time, use The present invention has been completed by finding that the sublimable dyes described above are easily transferred to a recording material to form a recorded image having high density and various fastnesses.

(Means for Solving Problems) That is, the present invention comprises a base material sheet and a dye-carrying layer provided on one surface of the base material sheet. A thermal transfer sheet comprising at least one of sublimable dyes represented by formulas (I) and (II).

[However, A in the formula is a hydrogen atom, -CONHR ₄ (R ₄ is a hydrogen atom or an alkyl group), (R ₅ is an amino group or an acylamino group.), —CO
CH ₂ COR ₆ (R ₆ is an alkyl group.) Or -CON (R ₇₎
-Ph (R ₇ is a hydrogen atom or an alkyl group), X ₁ and X ₂ are a hydrogen atom or a halogen atom, R ₁ is a hydrogen atom or an alkyl group, and R ₂ and R ₃ are alkyl. Group or a substituted alkyl group, B and C are hydrogen atoms, -CO
NHR ₄ , —COR ₆ , —COOR ₆ , amino group, alkylamino group or acylamino group. (Preferred Embodiment) Next, the present invention will be described in detail. The general formula (I) or (II) used in the present invention and mainly characterizing the present invention
The dye represented by is a material known per se, and is obtained by an oxidative coupling method of a P-phenylenediamino compound and a naphthol or a phenol. Conventionally, it is mainly a cyan color-developed color photograph. It was used as an agent.

The inventor of the present invention has conducted a detailed study on the applicability of such a conventional color photographic color forming agent to a new application as a dye for a heat transfer sheet as in the present invention, and as a result, many photographic dyes were heated. It is not suitable for sublimation, dyeability to a base sheet, heat resistance to heat during transfer, color developability after transfer, fastness after transfer, etc., and cannot be used for the purpose of the present invention. However, only the dye represented by the general formula (I) or (II) has a molecular weight of 350.
It has excellent heat sublimation property and heat resistance, and has excellent dyeing property on the base sheet,
The inventors have found that they exhibit color developability and, in addition, the transferability (bleeding property) of the dye in the transferred recording material is not observed, and that they have extremely ideal properties as a dye for a thermal transfer sheet.

In the present invention, particularly preferred dyes represented by the general formula (I) or (II) are those in which A and B are —CONHR ₄ and R ₄ is
It was found that it is a C ₁ -C ₆ alkyl group and R ₁ is a hydrogen atom or a methyl group.

Further, with respect to R ₂ and R ₃ , both are C _{1 to} C ₄ alkyl groups, and at least one of R ₂ and R ₃ is a hydroxyl group or a substituted hydroxyl group [for example, —O—R ′ (R ′ is Lower alkyl group, alkylcarbonyl group, etc.), amino group or substituted amino group [eg, —NH—R ″ (R ″ is an alkyl group, alkylcarbonyl group, alkylsulfonyl group, etc.)], cyano group, nitro group, etc. Those having a water-insoluble polar group have the best results, that is, those having excellent sublimation property, dyeing property to a base sheet, heat resistance at the time of transfer, and excellent migration resistance at the same time as color development. It was

In addition, the general formula (I) or (II) used in the present invention
It has been found that the dye represented by the formula (3) gives a recorded image having more excellent migration resistance when its molecular weight is 350 or more, preferably 400 to 700.

When the molecular weight is less than 350, the sublimation property and the like are satisfactory, but the transfer resistance after transfer is slightly lowered.

The thermal transfer sheet of the present invention is characterized by using the specific sublimable dye as described above, and other configurations may be the same as the configurations of conventionally known thermal transfer sheets.

The base sheet used for the constitution of the thermal transfer sheet of the present invention may be any one as long as it has a conventionally known degree of heat resistance and strength, for example, 0.5 to 50 μm,
Paper having a thickness of about 3 to 10 μm, various processed papers, polyester film, polystyrene film, polypropylene film, polysulfone film, polycarbonate film, polyvinyl alcohol film, cellophane and the like are preferable, and polyester film is particularly preferable.

The dye-carrying layer provided on the surface of the substrate sheet as described above is a layer in which the sublimable dye of the general formula (I) or (II) or a mixture thereof is carried by an arbitrary binder resin.

As the binder resin for supporting the sublimable dye as described above, any conventionally known binder resin can be used, and preferred examples include ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxycellulose, hydroxypropyl cellulose, methyl cellulose, and cellulose acetate. Cellulose resins such as cellulose acetate butyrate, polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinylpyrrolidone, vinyl resins such as polyacrylamide, and polyester are preferred from the viewpoints of heat resistance, migration of dyes, and the like. is there.

The dye-carrying layer of the thermal transfer sheet of the present invention is basically formed of the above-mentioned materials, but may contain various additives similar to those conventionally known, if necessary.

Such a dye-supporting layer is preferably prepared by adding the sublimable dye of the general formula (I) or (II) or a mixture thereof, a binder resin, and other optional components in a suitable solvent to dissolve or disperse each component. Then, a supporting layer-forming coating liquid or ink is prepared, and this is applied onto the above-mentioned substrate sheet and dried to form it.

The supporting layer thus formed has a thickness of about 0.2 to 5.0 μm, preferably about 0.4 to 2.0 μm, and the sublimable dye in the supporting layer is 5 to 70% by weight of the weight of the supporting layer, preferably
It is preferably present in an amount of 10-60% by weight.

The thermal transfer sheet as described above is sufficiently useful in the present invention as it is, but an anti-adhesion layer, that is, a releasing layer may be further provided on the surface of the dye-carrying layer. By providing such a layer, thermal transfer can be achieved. Prevents the thermal transfer sheet from sticking to the recording material, and uses a higher thermal transfer temperature,
An image having a more excellent density can be formed.

The release layer has a considerable effect even by simply adhering an anti-adhesive inorganic powder, and further, from a resin excellent in release property such as a silicone polymer, an acrylic polymer or a fluorinated polymer, 0.01 to 5 μm, preferably
It can be formed by providing a release layer having a thickness of 0.05 to 2 μm.

The inorganic powder or releasable polymer as described above can bring about sufficient effects even when incorporated in the dye carrying layer.

Further, 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 due to the heat of the thermal head.

The recording material used for forming an image using the thermal transfer sheet of the present invention has a dye-accepting property with respect to the recording surface of the dye of the general formula (I) or (II) or a mixture thereof. Any material may be used, and in the case of paper, metal, glass, synthetic resin or the like having no dye-receptive property, the dye-receptive layer may be formed on at least one surface thereof.

Examples of the recording material that does not need to form 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 and other vinyl monomers, ionomers,
Cellulose resins such as cellulose diacetate and cellulose triacetate, fibers made of polycarbonate, polysulfone, polyimide and the like, woven fabrics, films, sheets, molded products and the like can be mentioned.

Particularly preferred is a woven fabric, sheet or film made of polyethylene terephthalate.

Further, in the present invention, paper, metal, glass, or other non-dyeing recording material is coated or dried with a solution or dispersion of a dyeing resin as described above on its recording surface,
Alternatively, the recording material can be obtained by laminating those resin films.

Further, even for the recording material having the above dyeing property, a dye receiving layer may be formed on the surface of the recording material from a resin having a more dyeing property as in the case of the above paper.

The dye-receptive layer thus formed may be formed of a single dye or a plurality of dyes, and may further contain various additives within a range not hindering the object of the present invention. Of course.

Such a dye receiving layer may have any thickness, but is generally 5 to 50 μm thick. Further, such a dye receiving layer is preferably a continuous coating, but it may be formed as a discontinuous coating by using a resin emulsion or a resin dispersion liquid.

Such a recording material is basically as described above and can be used satisfactorily as it is. However, the recording material or the dye receiving layer thereof may contain an inorganic powder for preventing adhesion. By doing so, even if the temperature at the time of thermal transfer is raised, the adhesion between the thermal transfer sheet and the recording material can be prevented, and more excellent thermal transfer can be performed. Particularly preferred is finely divided silica.

Further, in place of or in combination with the above-mentioned inorganic powder such as silica, the above-mentioned resin having good releasability may be added. Particularly preferable releasing polymer is a cured product of a silicone compound, for example, a cured product of an epoxy-modified silicone oil and an amino-modified silicone oil.
Such a releasing agent may occupy about 0.5 to 30% by weight of the weight of the dye receiving layer.

Further, the recording material to be used may have the above-mentioned inorganic powder adhered to the surface of the dye receiving layer to enhance the anti-adhesion effect, and the release agent excellent in releasability as described above. You may provide the layer which consists of.

When such a release layer has a thickness of about 0.01 to 5 μm, it exerts a sufficient effect to prevent the thermal transfer sheet from sticking to the dye receiving layer and further improve the dye receiving property.

As the means for applying the thermal energy used when performing the thermal transfer using the thermal transfer sheet of the present invention and the recording material as described above, any conventionally known applying means can be used. For example, a thermal printer (for example, Toshiba ( ), manufactured by the thermal printer TN-5400) a recording device such as by controlling the recording time, by applying heat energy of about 5 to 100 mJ / mm ^2, it is possible to sufficiently achieve the object of the present invention it can.

(Operation / Effect) According to the present invention as described above, as partially described above, the dye of the general formula (I) or (II) or the mixture thereof used in the construction of the thermal transfer sheet of the present invention is
Compared with sublimable dyes (molecular weight of about 150 to 300) conventionally used for thermal transfer sheets of the same type, it has an extremely high molecular weight of 350 or more, but it has excellent heat sublimation property and dyeability to recording materials. In addition, it exhibits color developability, and does not migrate into the recording material or bleed out to the surface after transfer.

Therefore, the image formed using the thermal transfer sheet of the present invention has excellent fastness, especially migration resistance and stain resistance, so that the sharpness of the formed image is impaired even after long-term storage, or The various problems of the prior art have been fully solved without any contamination of other articles.

In particular, R ₂ and R ₃ as the dye of the above general formula (I) or (II)
In the case of a dye in which at least one of them has a polar group, the fastness as described above becomes more remarkable. Such an excellent effect which has not been heretofore conceivable is remarkable when the dye-receiving portion of the recording material is a material such as polyester, because the dye used in the present invention has many polarities as a whole molecule. Since it has a group, it is considered to be fixed in the polyester by some action due to the correlation with the ester bond which is a polar group in the polyester.

(Example) Next, an Example is given and this invention is demonstrated still more concretely. In the text, “part” or “%” is based on weight unless otherwise specified.

Examples 1 to 5 Ink compositions for forming a dye-carrying layer having the following compositions were prepared and applied to a polyethylene terephthalate film having a thickness of 9 μm and heat-treated on the back surface so that the dry coating amount was 1.0 g / m ^2. And dried to obtain the thermal transfer sheet of the present invention.

Dyes in Table 1 below 3 parts Polybutyral resin 4.5 parts Methyl ethyl ketone 46.25 parts Toluene 46.25 parts Synthetic paper (Yuji Po FPG # 1 manufactured by Oji Yuka Co., Ltd.) as a base sheet.
50) was used to apply a coating solution having the following composition to one surface thereof at a rate of 4.5 g / m ² when dried, and dried at 100 ° C for minutes to obtain a recording material.

Polyester resin (Vylon103, Toyobo, Tg = 47 ℃) 0.
8 parts EVA polymer plasticizer (Elvalloy 741P, Mitsui Polychemical, Tg = -37 ° C) 0.2 part Amino-modified silicone (KF-857, Shin-Etsu Chemical Co., Ltd.) 0.0
4 parts epoxy modified silicone (KF-103, manufactured by Shin-Etsu Chemical Co., Ltd.)
0.04 parts Methyl ethyl ketone / toluene / cyclohexane (weight ratio 4: 4: 2) 9.0 parts The thermal transfer sheet of the present invention and the recording material are superposed on each other with the dye carrying layer and the dye receiving layer facing each other. Recording was performed with a thermal head from the back surface of the thermal transfer sheet under the conditions of a head applied voltage of 10 V and an application time of 4.0 msec., And the results shown in Table 1 below were obtained.

In addition, the dye I is represented by the general formula (I): A = -CONH
R ₄ , R ₄ = n-butyl group, R ₁ = hydrogen, R ₂ = ethyl group, R ₃ =
It is an ethyl group dye.

Dye II is also represented by A = -CONHR ₄ , R ₄ = n-propyl group,
The dye has R ₁ = methyl group, R ₂ = ethyl group, and R ₃ = ethyl group.

Similarly, Dye III contains A = -CONHR ₄ , R ₄ = n-butyl group, R
₁ = hydrogen, R ₂ = ethyl, dye _{R 3 = -C 2 H 4 NHSO} 2 CH 3.

Similarly, the dye IV is A = -CONHR ₄ , R ₄ = n-butyl group, R ₁
= Methyl group, R ₂ = Ethyl group, R ₃ = Hydroxyethyl group.

The dye V is the same as A = -CONHR ₄ , R ₄ = n-propyl group,
The dye has R ₁ = hydrogen, R ₂ = methyl group, and R ₃ = methyl group.

In addition, in both dyes, X ₁ and X ₂ are hydrogen atoms.

Comparative Examples 1 to 5 The dyes shown in Table 2 below were used as the dyes in Examples 1 to 5, and the same results as shown in Table 2 below were obtained in the same manner as in Example 1.

The dye I'is CI Disperse Blue 14.

Dye II 'is C.I. Disperse Blue 134.

Dye III 'is C.I. Solvent Blue 63.

Dye IV ′ is C.I. Disperse Blue 26.

Dye V'is CI Disperse Violet 4.

The color densities in Tables 1 and 2 are the values measured by Densitometer RD-918 manufactured by Macbeth Co., USA.

The fastness is ◎ when the recorded image is left in an atmosphere of 50 ° C. for a long time and the sharpness of the image does not change, and the white paper is not colored even if the surface is rubbed with a white paper. If it was lost and the white paper was slightly colored,
When the sharpness was lost and the white paper was colored, it was indicated as Δ, and when the image became unclear, the white paper was markedly marked as x.

Examples 6 to 8 Instead of the dyes in Examples 1 to 6, the compound represented by the general formula (II) is used.
Using a dye whose substituents in are those in Table 3 below,
Others were the same as in Examples 1 to 6, and excellent results were obtained as in Examples 1 to 6.

Claims (3)

[Claims] 1. A substrate sheet and a dye carrying layer provided on one surface of the substrate sheet, wherein the dye contained in the dye carrying layer is represented by the following general formulas (I) and (II). A thermal transfer sheet comprising at least one sublimable dye. [However, A in the formula is a hydrogen atom, -CONHR ₄ (R ₄ is a hydrogen atom or an alkyl group), (R ₅ is an amino group or an acylamino group.), —CO
CH ₂ COR ₆ (R ₆ is an alkyl group.) Or -CON (R ₇₎
-Ph (R ₇ is a hydrogen atom or an alkyl group), X ₁ and X ₂ are a hydrogen atom or a halogen atom, R ₁ is a hydrogen atom or an alkyl group, and R ₂ and R ₃ are alkyl. Group or a substituted alkyl group, B and C are hydrogen atoms, -CO
NHR ₄ , —COR ₆ , —COOR ₆ , amino group, alkylamino group or acylamino group. ] 2. A dye represented by formula (I) or (II) having a molecular weight of 350 or more.
A thermal transfer sheet according to item. 3. The dye according to claim 1, wherein at least one of R ₂ and R ₃ of the dye represented by formula (I) or (II) is a lower alkyl group having a polar group. Thermal transfer sheet.