JP3349754B2 - Thermal transfer recording medium set - 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 recording medium set, and more particularly to a thermal transfer recording medium set having excellent scratch resistance and solvent resistance and capable of obtaining a high-resolution printed image.

[0002]

2. Description of the Related Art A heat-sensitive transfer recording medium having a heat-fusible ink layer provided on a heat-resistant base material is used. Receiving paper is superimposed on the surface of the heat-fusible ink layer and heated by a thermal head from the base material side. Then, a thermal transfer recording method is known in which the heat-meltable ink at the heated portion is melted and transferred to a receiving paper.

[0003] In order to improve the scratch resistance of a printed image obtained by such a method, the content of the wax component in the hot-melt ink layer is suppressed to a low level. In order to prevent this, there has been proposed a thermal transfer recording medium set in which a release layer is provided between a base material and a heat-meltable ink layer, and an overcoat layer is further provided on a receiving paper (JP-A-2-147291).

[0004]

However, when printing is performed by a thermal transfer printer or the like using the thermal transfer recording medium set having the release layer and the overcoat layer, the "tail" due to the softening of the overcoat layer. In some cases, "printing" and "print crushing" are observed, and instead of the absence of them, the scratch resistance and solvent resistance of the printed image are not good, or the resolution of the printed image is low. In order to prevent the overcoat layer from softening, it is conceivable to add a filler such as a pigment to the overcoat layer. However, when the heat-fusible ink layer contains a resin as a main component as in the above-described thermal transfer recording medium, There is a problem that the resolution of the printed image is lowered and the image is no longer returned.

That is, an object of the present invention is to provide a thermal transfer recording medium set which is excellent in abrasion resistance and solvent resistance and can obtain a clear printed image with high resolution.

[0006]

The present invention provides a heat-sensitive transfer recording medium in which a release layer and a heat-softening ink layer are sequentially laminated on a heat-resistant substrate, and an overcoat layer made of a thermoplastic resin on the substrate. In a heat-sensitive transfer recording medium set in which a receiving medium provided with a heat-softening ink layer and an overcoat layer are superposed on each other, the overcoat layer has a water-soluble or acid or alkali-soluble fine powder. After coating and forming a coating material containing, the fine powder is eluted by dipping in water or an acid or alkali aqueous solution to form continuous pores having a diameter of 0.01 to 1.0 μm, The softening ink layer has a glass transition temperature of -20 to 20.
The object is achieved by providing a resin containing a thermoplastic resin at 70 ° C.

When the diameter of the continuous pores in the overcoat layer of the receiving medium is less than 0.01 μm, the effect of providing the continuous pores is small, while when the diameter exceeds 1.0 μm, the surface of the receiving medium becomes rough. Instead, the printed image becomes worse. If the pores are not continuous pores but are cellular independent pores, the effect of preventing "tailing" or "crushing" of printing is small. The continuous pores should remain in the overcoat layer of the receiving medium, and when the continuous pores reach the substrate, the tensile strength of the substrate is significantly reduced. The number of continuous pores on the surface of the overcoat layer is determined by the size of the pores, but a quantity that damages a printed image is not preferable.

The thermoplastic resin constituting the overcoat layer preferably contains at least 30% by weight of at least one selected from polyurethane resins, saturated polyester resins, acrylic resins, acrylonitrile resins and ionomer resins. The thickness of the overcoat layer is 0.1
It is preferably about 20 μm.

As the base material of the receiving medium and the thermal transfer recording medium, a film made of a heat-resistant resin such as a polyester resin or a polyimide resin, or a thin paper such as glassine paper, tracing paper, or condenser paper can be suitably used.

The release layer of the thermal transfer recording medium has a thickness of 50 to 12
It is made of a material that melts at 0 ° C., and usually has a wax or a combination thereof with a resin as a main component, but can also be used in combination with a filler or the like. As wax,
Carnauba, montan, candelilla, paraffin, rice wax, polyethylene wax, etc., 50-1
Good results can be obtained by using a material that melts at 20 ° C. As the resin, good results can be obtained by using ethylene-vinyl acetate copolymer, acrylic resin, ethylene-acryl copolymer, polyvinyl acetate, ethyl cellulose, polyvinyl butyral, rosin, polyester, and the like.
As the filler, fine powders such as calcium carbonate, barium sulfate, aluminum oxide, and silica can be used.

The heat-softening ink layer of the thermal transfer recording medium is
Commonly known black pigments such as carbon black and graphite, or CI. No. 12475 (red), 15850: 1 (red), 21090 (yellow), 21095 (yellow), 21105 (yellow), 73915 (magenta), 74160 (blue)
Colorants including color pigments such as, carnauba, waxes such as microcrystalline wax, polypropylene, ethylene-vinyl acetate copolymer, polyamide resin,
It is made of a thermoplastic resin such as a polyurethane resin, a saturated polyester resin, an acrylic resin, an acrylonitrile resin, and an ionomer resin. When considering oil resistance, alcohol resistance, acid resistance, and the like, it is preferable to use a polyurethane resin, a saturated polyester resin, an acrylic resin, an acrylonitrile resin, or an ionomer resin. If the glass transition temperature is -20 to 70 ° C., a material having high printing sensitivity can be obtained. In particular, using a polyester resin,
Partially curing it gives better results in solvent and chemical resistance. The resin is preferably contained in the thermosoftening ink layer in an amount of 30% by weight or more. 30
When the amount is less than the weight%, the cohesive force is reduced and the scratch resistance is reduced. On the other hand, the wax is preferably used in an amount of 30% by weight or less in the thermosoftening ink layer. If it is used in an amount of 30% by weight or more, the abrasion resistance, solvent resistance, chemical resistance, etc. decrease. In addition, calcium carbonate,
Fillers such as barium sulfate, aluminum oxide and silica, and additives such as lubricating oil can be added.

To manufacture a thermal transfer recording medium, first, carnauba wax or the like is applied on a heat-resistant substrate to form a release layer, and then a thermoplastic resin having a glass transition temperature of -20 to 70 ° C. and a coloring agent A coating material obtained by dissolving or dispersing (emulsifying) a material to which an additive such as a wax is added as necessary in a solvent is applied onto the release layer. Note that a stick prevention layer may be provided in advance on the surface of the substrate opposite to the surface on which the coating material is applied.

In order to produce a receiving medium, a substrate obtained by dissolving a thermoplastic resin in an appropriate solvent is applied on a substrate to form an overcoat layer. The fine continuous holes in the overcoat layer are formed by (1) applying a mixture of a substance that foams by light or heat dispersed and mixed in the overcoat layer coating material, and applying or applying light or heat at that time. Foaming method: (2) A dispersion in which a water-soluble inorganic salt such as sodium chloride or a fine powder of a water-soluble resin such as starch is dispersed and mixed in an overcoat layer coating material is formed and then immersed in an aqueous solution. (3) A fine powder of an acid or an alkali-soluble substance is dispersed and mixed in a coating material for an overcoat layer, and then the mixture is formed by acidification. Alternatively, it can be formed by a method of immersing in an alkaline solution to elute the fine powder of the soluble substance; or (4) a method of perforating with a physical means such as a needle or the like, but is not limited to these methods.

[0014]

As means for improving the scratch resistance and solvent resistance of a printed image by thermal transfer, there is a method of increasing the cohesive force of the transferred ink. For this purpose, a resin having an extremely high molecular weight may be used for the thermosoftening ink layer of the thermal transfer recording medium. However, if this method is used, the transfer sensitivity of the ink is reduced, so that there is a problem that the printed image is not clear.

Therefore, an overcoat layer (thermosensitive adhesive layer) made of a thermoplastic resin is provided on the surface of the receiving medium, and an image is printed on the overcoat layer. It has been found that the sharpness of the printed image can be maintained without lowering the transfer sensitivity even when an extremely large resin is used. The thermal transfer recording medium set described in Japanese Patent Application Laid-Open No. 2-147291 is based on this fact.

In order to increase the printing sensitivity, the glass transition temperature (Tg) of the thermoplastic resin used for the heat-sensitive adhesive layer is required.
However, in such a case, "tailing" or "crushing" of the print occurs, so that clear print cannot be obtained. That is, in order to maintain the sharpness of the printed image,
The problem that large heat energy is required for transfer remains.

In order to solve this problem, in the present invention, an overcoat layer having continuous pores is provided on the surface of the receiving medium. The overcoat layer can be made of substantially the same kind of resin as that of the thermal transfer recording medium set described in the above-mentioned publication, but even if a resin having a low glass transition temperature (Tg) is used in order to increase printing sensitivity. In addition, since there are continuous pores, clear printing can be obtained without causing "tailing" or "crushing" of printing.

[0018]

【Example】

[Example] A 3.5 μm thick P was used as a thermal transfer recording medium.
A silicone resin dissolved in MEK (methyl ethyl ketone) is applied to one side of an ET (polyethylene terephthalate) film to provide a 0.3 μm thick stick prevention layer, and then carnauba wax is formed on the side opposite to the stick prevention layer. A release layer having a thickness of 1.0 μm is provided, and a coating material obtained by dissolving 16 parts of a polyester resin and 9 parts of carbon black in 75 parts of MEK is applied on the release layer to a thickness of 1.2 μm to form a heat-softening ink. Layers were provided. Next, as a receiving medium (paper to be transferred), a coating solution prepared by dissolving 10 parts of a polyester resin and 15 parts of calcium carbonate in 75 parts of MEK was applied to one side of a 38 μm thick polyester film with a coating rod bar to a thickness of 15 μm. And then brought to pH 3
After immersion in an aqueous citric acid solution adjusted for 5 minutes, the resultant was washed with water and dried to form an overcoat layer having fine continuous holes with a pore diameter of about 0.10 μm.

When printing was performed by a word processor (FW-UIP611, manufactured by Matsushita Electric Industrial Co., Ltd.) using the thermal transfer recording medium set including the thermal transfer recording medium and the receiving medium, "tailing" and "crushing" of the print occurred. A printed image without "" was obtained. Various fastnesses including solvent resistance and scratch resistance were evaluated as follows. Ethanol impregnated ethanol-resistant cotton (2cm x 2cm)
The substrate was rubbed 100 times with a load of 500 g / cm ² . The test machine used was "Love Tester" manufactured by Yasuda Seiki Seisakusho. Eraser Fastness An eraser was pressed against a printed matter with a load of 100 g / 78.5 mm ² and rubbed 80 times at a speed of 3000 mm / min. The test machine is made by HEIDON "SURFACEPRO
PERTY TESTER "was used. A sapphire needle is pressed onto a scratch-fast printed material without any load, and 3000 m
Rubbing was performed 50 times at a speed of m / min. Test machine is HEID
ON "SURFACE PROPERTYTESTE"
R "was used. Cellotape fastness Stick Nichiban cellotape on the printed material,
° Peeling was performed. The OD (optical density) of the printed matter after the solvent resistance and fastness tests was 70% or more of the initial value. In addition, no stain or falling off of the printed portion was observed.

[Comparative Example] Printing was performed by the same word processor using the same thermal transfer recording medium set as in the above embodiment except that fine continuous holes were not provided in the overcoat layer. "And" crush ". The OD of the printed matter after the above-mentioned solvent resistance and fastness tests was 3 as the initial value.
0% to 40%.

[0021]

As described above, by using the thermal transfer recording medium set of the present invention, a clear printed image having excellent scratch resistance and solvent resistance and having no "tailing" or "crushing" of a printed image can be obtained. Can be

[Brief description of the drawings]

FIG. 1 is a schematic view illustrating a mechanism for performing thermal transfer printing using a thermal transfer recording medium set of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermal transfer recording medium 11 Heat resistant base material 12 Stick prevention layer 13 Release layer 14 Thermal softening ink layer 2 Receiving medium 21 Base material 22 Overcoat layer 23 Fine continuous pores 3 Thermal head

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B41M 5/38-5/40

Claims (7)

(57) [Claims] 1. A heat-sensitive transfer recording medium in which a release layer and a thermosoftening ink layer are sequentially laminated on a heat-resistant base material, and a receiving medium in which an overcoat layer made of a thermoplastic resin is provided on the base material. In a thermal transfer recording medium set in which a heat-softening ink layer and an overcoat layer are overlapped so as to face each other, the overcoat layer is formed by applying a coating material containing a water-soluble or acid or alkali-soluble fine powder. Thereafter, the fine powder was eluted by immersion in water or an acid or alkali aqueous solution to form
A heat-sensitive transfer recording medium set having continuous pores of 1 to 1.0 μm, and wherein the thermosoftening ink layer contains a thermoplastic resin having a glass transition temperature of −20 to 70 ° C. 2. The feeling according to claim 1, wherein the thermoplastic resin of the overcoat layer contains at least 30% by weight of at least one of polyurethane resin, saturated polyester resin, acrylic resin, acrylonitrile resin and ionomer resin. Thermal transfer recording medium set. 3. The thickness of the overcoat layer is 0.1 to 2
2. The thermal transfer recording medium set according to claim 1, which has a thickness of 0 [mu] m. 4. The thermal transfer recording medium set according to claim 1, wherein said thermosoftening ink layer comprises a colorant, a wax and a thermoplastic resin. 5. The thermosoftening ink layer has a wax content of 30% by weight or less and a thermoplastic resin content of 3% by weight.
The thermal transfer recording medium set according to claim 4, wherein the content is 0% by weight or more. 6. The thermal transfer recording medium set according to claim 1, wherein the thermoplastic resin of the thermosoftening ink layer is at least one of a polyurethane resin, a saturated polyester resin, an acrylic resin, an acrylonitrile resin and an ionomer resin. 7. The thermal transfer recording medium set according to claim 4, wherein said colorant is a pigment.