JP2571752B2 - Thermal transfer sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer sheet.

[0002]

2. Description of the Related Art In recent years, as a recording method for recording an image such as a photograph directly from an image on a CRT display, a thermal transfer sheet is heated by a thermal head or the like whose heat is controlled by an electric signal. A thermal transfer recording system in which a sublimable dye in a color material layer is transferred to a thermal transfer transfer sheet to record image information is employed.

This thermal transfer recording system has attracted attention as a system capable of transferring and recording a color image having a continuous change in color density by superimposing and recording three primary colors of cyan, magenta and yellow.

As a thermal transfer sheet used in the thermal transfer recording method, a sheet in which a coloring material layer is formed by applying a binder containing a sublimable dye to a base material has been conventionally used.

[0005]

However, in the conventional sublimation transfer paper for fabric, since the dye is dispersed in the binder, the interaction between the dye molecules and the dye molecule to the binder are required to sublimate the dye. Energy must be overcome to overcome the interaction between the dyes, and high thermal energy is required for dye sublimation transfer,
There was a problem that the thermal sensitivity at the time of thermal transfer was reduced.

[0006] The present invention has been made in view of the above points,
An object of the present invention is to provide a thermal transfer sheet that solves the above-mentioned conventional problems.

[0007]

In other words, the thermal transfer sheet of the present invention has Disperse Yellow 201 on one surface of a substrate.
And a color material layer formed of a composition containing a binder.

[0008] The base material of the thermal transfer sheet of the present invention includes plastics such as condenser paper, polyester film, polyethylene naphthalate film, polystyrene film, polysulfone film, polyimide film, polyvinyl alcohol film, cellophane, and aramid (aromatic polyamide) film. A film is used and has a thickness of 2 to 50 μm, preferably 2 to 12 μm. These plastic films are preferable because they have a smooth surface and a high mechanical strength. Among them, it is preferable to use a polyester film or an aramid film.

A color material layer is provided on one surface of the base material. The thermal transfer sheet of the present invention has a color material layer formed of a composition containing Disperse Yellow 201 as a dye and a binder. In the present invention, since the dye is dissolved in the binder, when the dye is sublimated and transferred, as in a conventional thermal transfer sheet in which the dye is present in a dispersed state in the binder, the interaction between the dye molecules and the dye molecule ~
There is no need for energy for overcoming the interaction between the binders, and there is an advantage of excellent thermal sensitivity.

In order to obtain a multicolored transfer image, a yellow transfer image from a yellow color material layer using Disperse Yellow 201 as a dye contains a color material layer containing a cyan dye and a magenta dye. Cyan and magenta dyes are sublimated and transferred from the color material layer, and overprinted. In order to obtain a black transfer image, it is necessary that the color material layer contains a black dye. Each dye of cyan, magenta, and black is preferably a sublimable disperse dye, a sublimable oil-soluble dye, a sublimable basic dye, or the like, and has a molecular weight of 150 to 800,
Preferably it is 350-700. These dyes are selected in consideration of the sublimation temperature, hue, weather resistance, solubility in the ink or binder, and the like, but are preferably dissolved in the binder.

Examples of cyan, magenta and black dyes include C.I. I. (Abbreviation of color index; the same applies hereinafter) Disperse Blue 24, 56, 14, 301, 334, 165, 19, and 7
2, 87, 287, 154, 26; C.I. I. C. disperse thread 135, 146, 59, 1, 73, 60, 167; I. C. Disperse Violet 4, 13, 13, 36, 56, 31; I.
Solvent Violet 13; C.I. I Solvent Black 3; I. Solvent Green 3; I Solvent Blue 70, 35, 63, 36, 50, 4
9, 111, 105, 97, and 11; C.I. I. Solvent Red 135, 81, 18, 25, 1
9, 23, 24, 143, 146, and 182.

Examples of the binder used for forming the colorant layer together with the above dyes include cellulose resins such as ethylcellulose, hydroxyethylcellulose, ethylhydroxyethylcellulose, hydroxypropylcellulose, methylcellulose, cellulose acetate and cellulose acetate butyrate, polyvinyl alcohol, polyvinyl butyral. And vinyl resins such as polyvinylpyrrolidone, polyester, polyvinyl acetate and polyacrylamide.

It is desirable that the weight ratio of the dye and the binder in the color material layer is such that dye / binder ≧ 0.3, and if the dye / binder <0.3, the printing density and the thermal sensitivity are insufficient. When the ratio of dye / binder> 2.3, the retention of the dye in the binder is insufficient, and the storage stability of the thermal transfer sheet is reduced. Therefore 2.3 ≧ dye /
It is preferred that binder ≧ 0.3, more preferably 1.5 ≧ dye / binder ≧ 0.55. The color material layer can be formed by, for example, applying a composition comprising the dye and the binder on a substrate.

The surface of the substrate of the thermal transfer sheet can be subjected to a treatment for preventing fusion with a thermal head.

As the heat transfer sheet to be used in combination with the heat transfer sheet, a receiving layer for transferring a sublimable dye of the heat transfer sheet by heating to form a record corresponding to image information, and a substrate carrying the receiving layer And those composed of the following. In order to further enhance the sharpness of the transferred image, it is preferable that a cushion layer is provided between the receiving layer and the substrate.

As the base material of the heat transfer sheet, synthetic paper (polyolefin type, polystyrene type, etc.), high quality paper,
Art paper, coated paper, cast coated paper, wallpaper backing paper, synthetic resin or emulsion impregnated paper, synthetic rubber latex impregnated paper, synthetic resin internal paper, paperboard, or natural fiber paper such as cellulose fiber paper, polyolefin, polyvinyl chloride , Polyethylene terephthalate, polystyrene,
Various plastic films or sheets such as polymethacrylate and polycarbonate can be used.

The base material of the sheet to be heat-transferred is as described above.
Of these, the synthetic paper is preferable because it has a microvoid layer having low thermal conductivity (in other words, high heat insulation) on its surface. In addition, a laminate formed by any combination of the above-mentioned to (1) can also be used. Typical examples of the laminate include a laminate of cellulose fiber paper and synthetic paper, or a laminate of cellulose fiber paper and a plastic film or sheet. Of these, the laminate of cellulose fiber paper and synthetic paper can compensate for the thermal instability (e.g., expansion and contraction) of synthetic paper by cellulose fiber paper and exhibit high printing sensitivity due to the low thermal conductivity of synthetic paper. Good. In addition, in order to balance the front and back of the laminate in this combination, it is preferable to use a three-layer laminate of synthetic paper-cellulose fiber paper-synthetic paper,
Curling due to printing can be reduced.

The synthetic paper used for the above-mentioned laminate is usually
Any material can be used as long as it can be used as a base material of the heat transfer sheet. In particular, synthetic paper provided with a paper-like layer having fine pores (for example, commercially available synthetic paper, Yupo: Oji Oil Chemicals) Paper). The fine pores in the paper-like layer can be formed, for example, by stretching a synthetic resin containing a fine filler. A thermal transfer sheet formed using synthetic paper provided with a paper-like layer having fine holes has a high image density of a transfer image formed by thermal transfer,
There is an effect that the image is not rough. This is thought to be due to the fact that the fine pores have a heat insulating effect, that the thermal energy efficiency is good, and that the receiving layer provided on the synthetic paper has good cushioning properties due to the fine pores. It is also possible to provide a paper-like layer containing fine pores directly on the surface of a core material such as cellulose fiber paper.

A plastic film can be used besides the cellulose fiber paper in the above-mentioned laminate.
What laminated | stacked the said cellulose fiber paper and a plastic film can also be used. The thickness of the substrate is usually preferably from 30 to 200 μm.

Examples of the method of adhering the synthetic paper and the cellulose fiber paper include pasting using a conventionally known adhesive, pasting using an extrusion laminating method, and pasting by thermal bonding. Examples of the method for attaching the plastic film and the plastic film include a method using a laminating method, a calendar method, and the like that simultaneously form the plastic film. The sticking means is appropriately selected according to the material of the material to be stuck to the synthetic paper.

As a specific example of the above adhesive, ethylene /
Emulsion adhesives such as vinyl acetate copolymers and polyvinyl acetates; water-soluble adhesives such as polyesters containing carboxyl groups; etc .; and adhesives for laminating include organic solvent solutions such as polyurethane-based and acrylic-based. An adhesive such as a type may be used.

The receiving layer of the heat transfer sheet is made of a material capable of receiving an image of the dye transferred from the heat transfer sheet and maintaining the received image of the dye. As the material constituting the receiving layer, any material can be used as long as it is conventionally used for the receiving layer of this type of heat transfer sheet. For example:
The synthetic resins (a) to (e) can be used alone or in combination of two or more.

(A) A resin having an ester bond. For example, polyester resin, polyacrylate resin, polycarbonate resin, polyvinyl acetate resin, styrene acrylate resin, vinyl toluene acrylate resin. (b) A resin having a urethane bond. For example, polyurethane resin and the like. (c) a resin having an amide bond. Polyamide resin (nylon). (d) A resin having a urea bond. For example, urea resin and the like. (e) Other resins having a highly polar bond. For example, polycaprolactone resin, polystyrene resin, polyvinyl chloride resin, polyacrylonitrile resin and the like.

The receiving layer is composed of a saturated polyester and vinyl chloride /
It can be composed of a mixture with a vinyl acetate copolymer. In this case, the vinyl chloride / vinyl acetate copolymer has a vinyl chloride component content of 85 to 97% by weight and a degree of polymerization of 20.
Those having about 0 to 800 are preferable. As the vinyl chloride / vinyl acetate copolymer, those containing vinyl alcohol, maleic acid, etc. in addition to vinyl chloride and vinyl acetate as comonomer components can be used.

When the receiving layer is made of a polystyrene resin, a homopolymer or copolymer of a styrene resin such as styrene, α-methylstyrene or vinyltoluene as the polystyrene resin, or these styrene monomers and other monomers, For example, copolymers with acrylic or methacrylic monomers such as acrylic acid esters, methacrylic acid esters, acrylonitrile, and methacrylonitrile, and maleic anhydride are exemplified.

In order to improve the sharpness of the transferred image by improving the whiteness of the receiving layer, to provide writing properties on the surface of the sheet to be heat-transferred, and to prevent retransfer of the transferred image. Can be added with a white pigment. When a white pigment is added to the receiving layer, it is possible to transfer an image having higher definition, excellent heat resistance, excellent moisture resistance and the like. Furthermore, the color (yellowishness) peculiar to the resin such as the receiving layer and the cushion layer laminated on the base material can prevent the whiteness and glossiness of the base material from being impaired. This effect is large because whiteness, gloss and smoothness are inferior to synthetic paper and the like.

As the white pigment, titanium oxide, zinc oxide, kaolin clay and the like are used, and these can be used in combination of two or more. The addition amount of the white pigment is preferably 5 to 50 parts by weight based on 100 parts by weight of the resin constituting the receiving layer.

An ultraviolet absorber may be added to the receiving layer. By adding an ultraviolet absorber, the light resistance of the dye transferred from the thermal transfer sheet is further improved. Examples of the ultraviolet absorber include a benzophenone type, a hindered amine type, and a benzotriazole type. The amount of the ultraviolet absorber added is about 0.05 to 5 parts by weight based on 100 parts by weight of the resin constituting the receiving layer.

In order to enhance the releasability of the heat transfer sheet and the heat transfer sheet after the transfer and the heat transfer sheet are superimposed and heated, a releasing agent is contained in the receiving layer of the heat transfer sheet. Can be. Examples of the release agent include solid waxes such as polyethylene wax, amide wax, and terflon powder, fluorine-based and phosphate-based surfactants, and silicone oil. Silicone oil is preferred.

As the silicone oil, an oily one can be used, but a hardening type is preferred. Examples of the curable silicone oil include a reaction curable type, a photocurable type, and a catalyst curable type, and a reaction curable type silicone oil is particularly preferable. The reaction-curable silicone oil is preferably one obtained by reacting and curing an amino-modified silicone oil and an epoxy-modified silicone oil. The addition amount of these curable silicone oils is preferably 0.5 to 30 parts by weight based on 100 parts by weight of the resin constituting the receiving layer.

Further, the releasing agent layer may be provided by dissolving or dispersing the above releasing agent in an appropriate solvent on the surface of the receiving layer, followed by drying and the like. As the release agent constituting the release agent layer, a cured product of the above-mentioned amino-modified silicone oil and epoxy-modified silicone oil is particularly preferable. The thickness of the release agent layer is 0.01 to 5 μm,
Particularly, the thickness is preferably 0.05 to 2 μm. The release agent layer may be provided on a part of the surface of the receiving layer or on the entire surface. However, when provided on a part of the surface of the receiving layer, dot impact recording, heat-sensitive Melt transfer recording, recording with a pencil or the like can be performed, sublimation transfer recording is performed on the part where the release agent layer is provided, and recording using another recording method is performed on the part where the release agent layer is not provided Sublimation transfer recording method and other recording methods can be performed together.

A lubricating layer can be provided on the back surface of the substrate of the heat transfer sheet. In some cases, the heat transfer sheets are transferred one by one from the stacked state to perform the transfer. In this case, if a slipping layer is provided, the slip between the sheets becomes smooth, and the sheets can be precisely sent out one by one. Examples of the material of the lubricating layer include methacrylate resins such as methyl methacrylate or acrylate resins, and vinyl resins such as vinyl chloride / vinyl acetate copolymer.

The cushion layer optionally provided between the base material and the receiving layer is a soft layer having a cushioning property, and preferably has a 100% modulus of 250 kg / cm ² or less. The cushion layer is provided to allow the receiving layer to change corresponding to the tip of the head when pressed by the thermal head or the like during printing,
The thicker the thickness, the better the cushioning property can be given, and thus the print density can be improved.

Specific examples of the cushion layer include polyurethane resin, polyester resin, acrylic resin, ethylene / vinyl acetate copolymer resin, vinyl acetate / acryl copolymer resin, polyvinyl chloride resin, polyethylene resin,
Polypropylene resin, polystyrene resin, polyurethane elastomer, epoxy resin, vinyl chloride / vinyl acetate copolymer resin, polyvinyl acetate resin, alkyl titanate, polyethylene imine, polybutadiene, ethylene /
Examples include a layer made of an acrylic copolymer resin, an ionomer, or the like.

As described above, as the thickness of the cushion layer is larger, better cushioning properties can be obtained. However, if the thickness is too large, the thickness of the entire heat transfer sheet increases.
It is preferable to select the thickness within a range of about 1 to 200 μm as needed. More preferably, the thickness of the cushion layer is 3-7.
0 μm, and particularly preferably about 5 to 40 μm.

As a method of forming the cushion layer, besides ordinary solution coating, extrusion coating, hot melt coating and the like can be used. A method in which a suitable support is impregnated with a cushion layer-forming ink composition is sandwiched between a substrate and a receptor layer can also be employed.

It is also possible to form fine bubbles in the cushion layer to further enhance the cushioning property. In order to form bubbles, a W / O emulsion is used as the ink composition for forming the cushion layer, a foaming agent is added, the ink composition for forming the cushion layer is impregnated into a nonwoven fabric or the like, and the ink composition for forming the cushion layer is formed. When applying the ink, a method such as stirring the air bubbles into the ink composition can be used.

As described above, the thicker the cushion layer is, the higher the cushioning property is obtained. However, if the cushion layer is too thick, drying tends to be insufficient at the time of production, and blocking during the storage of the sheet may cause blocking. Is often caused. If it is attempted to dry sufficiently to prevent this problem, the cost will be high both in terms of time and equipment, and practically it will be difficult to manufacture. On the other hand, if the thickness of the cushion layer is too large, the resin of the cushion layer bleeds into the receiving layer and causes density unevenness during printing.

In order to solve such a problem, it is preferable to interpose a sheet material for separating the two layers between the receiving layer and the cushion layer. Examples of the material of the sheet include polyethylene terephthalate, stretched polypropylene, unstretched polypropylene, ethylene / vinyl acetate copolymer, ionomer, cellulose acetate, polycarbonate, hard and semi-hard vinyl chloride, and the like. Also, paper such as condenser paper can be used. The thickness of the sheet is preferably about 2 to 60 μm.

When the above-mentioned sheet-like material is interposed between the receiving layer and the cushion layer, the bleeding of the image due to the transfer of the ink transferred to the receiving layer to the cushion layer can be prevented. When a cushion layer is provided in contact with the receiving layer, the resin of the cushion layer migrates to the receiving layer.
The resin constituting the cushion layer could not be used unless it also had the suitability as the receiving layer. However, such a problem can be solved by interposing the sheet-like material.

Each of the layers constituting the heat transfer sheet may be a transparent layer, or one or two or more layers may be opaque.

The heat transfer sheet can be subjected to an antistatic treatment with an antistatic agent. By performing the antistatic treatment, the slip between the sheets can be made smoother, and the adhesion of dust to the heat transfer sheet can be prevented. The antistatic treatment may be performed by including an antistatic agent in the base material, the slipping layer provided on the back surface of the receiving layer or the base material, or by providing a layer containing the antistatic agent on the back surface of the base material, The latter method is preferred.

The heat transfer sheet can be provided with a detection mark which is convenient for positioning the heat transfer sheet and the heat transfer sheet. The detection mark can be formed by printing or the like. For example, a detection mark that can be detected by a photoelectric tube detection device is provided on the back surface of the base material.

In order to transfer to the heat transfer sheet by the heat transfer sheet, the color material layer of the heat transfer sheet and the receiving layer of the heat transfer sheet are overlapped so that they are in contact with each other, and a thermal head or the like is used from the substrate side of the heat transfer sheet. Heating may be performed, and after the heating, the dye in the color material layer of the thermal transfer sheet is transferred onto the receiving layer of the thermal transfer sheet according to the information heated by the thermal head by peeling off the thermal transfer sheet. An image corresponding to the image information is recorded thereon.

[0045]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1 The following ink composition for forming a cushion layer was prepared and coated on a coated paper (basis weight: 104.7 g / m ² ) so that the coated amount after drying was 10 g / m ² .

Cushion layer formation ink composition ・ Polyurethane resin (Takelac A-712B: manufactured by Takeda Pharmaceutical) 30 parts by weight ・ Isocyanate curing agent (Takenate A-72B: Takeda Chemical) 18 parts by weight ・ Ethyl acetate 52 parts by weight

A 12 μm-thick polyester film (Lumirror, manufactured by Toray) was laminated as a sheet on the coated surface of the ink composition 1. Next, the following ink composition for a receiving layer was prepared and applied onto the sheet-like material so that the coating amount after drying was 4 g / m ² to obtain a heat-transferable sheet.

Ink composition for forming receiving layer: 70 parts by weight of polyester resin (Vylon 200: manufactured by Toyobo) 30 parts by weight of polyester resin (Vylon 290: manufactured by Toyobo) Amino-modified silicone (KF-393: manufactured by Shin-Etsu Chemical) 5 5 parts by weight ・ Epoxy-modified silicone (X-22-343: manufactured by Shin-Etsu Chemical) 5 parts by weight ・ 350 parts by weight of methyl ethyl ketone ・ 350 parts by weight of toluene

On the other hand, a 4.5 μm-thick polyester film (Lumirror: manufactured by Toray Co., Ltd.) having a heat-resistant lubricating layer made of a thermosetting acrylic resin on one side is used as a base material, and is opposite to the side on which the heat-resistant lubricating layer is provided. On the other side, the following ink composition was applied so that the coating amount after drying was 1 g / m ² to obtain a color material layer to obtain a thermal transfer sheet.

Ink composition for forming color material layer (cyan) 4 parts by weight of disperse dye (Kayaset Blue 714: manufactured by Nippon Kayaku) 6 parts by weight of polyvinyl butyral resin (Eslek BX-1: manufactured by Sekisui Chemical) 45 parts by weight ・ Toluene 45 parts by weight

Ink composition for forming color material layer (magenta)-Disperse dye (MS Red G: manufactured by Mitsui Toatsu Chemical [Disperse Red 60]) 2.6 parts by weight-Disperse dye (Macrolex Violet R: manufactured by Bayer Perth Violet 26]) 1.4 parts by weight-Polyvinyl butyral resin (S-Rex BX-1: manufactured by Sekisui Chemical) 4.3 parts by weight-Methyl ethyl ketone 45 parts by weight-Toluene 45 parts by weight

Ink composition for forming colorant layer (yellow) Disperse dye (Macrolex Yellow 6G: manufactured by Bayer [Disperse Yellow 201]) 5.5 parts by weight Polyvinyl butyral (Eslek BX-1: manufactured by Sekisui Chemical) 4 0.5 parts by weight ・ Methyl ethyl ketone 45 parts by weight ・ Toluene 45 parts by weight

Using the thermal transfer sheet and the thermal transfer sheet, printing was performed with a thermal head having a dot density of 6 dots / mm under the following printing conditions.

Printing conditions • Printing speed 33.3 ms / line • Feed pitch 0.166 mm • Pulse width 12.0 ms • Head applied voltage 11.0 V

The reflection density of cyan transferred and printed on the heat transfer sheet was measured using a Macbeth color densitometer RD-918, and was 1.95. The print density was uniform over the entire print surface, No omission was seen. In addition, the print density was high for all three colors, and good images were obtained without roughness, color misregistration, and uneven formation. By controlling the electric energy applied to the head by changing the pulse width, an arbitrary print density in the range of 0 to 2.2 can be obtained with good reproducibility.

Next, printing was performed under the same conditions as described above by changing the thickness of the cushion layer of the heat transfer sheet (changing the amount of the ink composition for forming the cushion layer). Table 1 shows the reflection densities and print qualities of the transferred cyan, magenta, and yellow colors.

[0058]

[Table 1]

Incidentally, the evaluation of the printing quality in the above Table 1 was evaluated as ◎: extremely good ○: good

Example 2 A receiving layer was coated in the same manner as in Example 1 using coated paper (basis weight: 104.7 g / m ² ) (coating amount: 4 g / m ² ).
m ² ) to obtain a heat transfer sheet. When printing was performed using this heat transfer sheet in the same manner as in Example 1, unevenness in print density and missing dots due to uneven formation of the coated paper used as the base material were observed. The reflection density of cyan was 1.48, the reflection density of magenta was 1.36, and the reflection density of yellow was 1.45.

Example 3 A coated paper (basis weight: 104.7 g / m ² ) was used as a substrate, and a W / O type polyurethane resin emulsion (Samprene UE-1000N: manufactured by Sanyo Chemical Co., Ltd.) was dried thereon. Was applied so as to be 10 g / m ² to form a resin layer containing fine bubbles, and a 12 μm-thick polyester film (Lumirror: manufactured by Toray) used as a sheet was laminated thereon.

Next, a receptor layer was applied in the same manner as in Example 1 (coating amount: 4 g / m ² ) to obtain a heat transferable sheet. When printing was performed on this heat transfer sheet in the same manner as in Example 1, the printing density was uniform over the entire printing surface, and no missing dots were observed.

Example 4 The same ink composition for forming a cushion layer as in Example 1 was applied to a nonwoven fabric (Diaheat 20: manufactured by Mitsubishi Paper Mills, basis weight 20.6 g /
m ² ), and after drying, one side was laminated with coated paper (basis weight 104.7 g / m ² ) used as a substrate, and the other side was used as a sheet. It was laminated with a polyester film having a thickness of 12 μm (Lumirror: manufactured by Toray Industries, Inc.) to form a resin layer containing fine bubbles. Next, the same ink composition for forming a receptor layer as in Example 1 was applied on this sheet so that the coating amount at the time of drying was 4 g / m ² to obtain a heat transfer sheet.

Using this heat transfer sheet, printing was performed in the same manner as in Example 1. As a result, the print density was uniform over the entire print surface, and no missing dots were observed. The reflection density of the transferred cyan was 2.01.

[0065]

The thermal transfer sheet of the present invention has a color material layer formed of a composition containing Disperse Yellow 201 and a binder, and the dye used in the present invention is dissolved in the binder. It is not necessary to give the energy that overcomes the interaction between the dye molecules or the interaction between the dye molecule and the binder at the time of heat transfer, as in the case of dispersing in the heat transfer. Has the effect that can.

Claims (1)

(57) [Claims] 1. A thermal transfer sheet having a color material layer formed on one surface of a substrate with a composition containing Disperse Yellow 201 and a binder.