JP2020090017A - Sublimable thermal transfer image receiving sheet - Google Patents

Abstract

To provide a sublimable thermal transfer image receiving sheet capable of printing with high density while suppressing an occurrence of a JAM due to triboelectrification between a dye layer of a thermal transfer sheet and a thermal transfer image receiving sheet, at an initial operation of a printer.SOLUTION: A sublimable thermal transfer image receiving sheet includes: at least an image receiving layer on one side of a substrate; and at least a back surface layer on the other side of the substrate. The image receiving layer includes, as a main component, a vinyl copolymer emulsion containing at least a vinyl chloride as a first constituent, as a resin content. An atomic ratio (Cl/C) of surface chlorine (Cl) to surface carbon (C) of the image receiving layer is 15-25%.SELECTED DRAWING: Figure 1

Description

The present invention relates to a thermal transfer image-receiving sheet, and more particularly to a sublimation type thermal transfer image-receiving sheet for forming a transfer image by transferring a dye of the thermal transfer sheet by superposing a sublimation type thermal transfer sheet thereon and heating it.

Conventionally, a sublimation type thermal transfer system, a fusion type thermal transfer system and the like have been adopted as a printing system for forming characters or images on a transferred body.

The sublimation type thermal transfer system is a method in which the colored ink layer in the sublimation type thermal transfer sheet and the image receiving layer in the thermal transfer image receiving sheet are superposed on each other and then heated by a thermal head whose heat generation is controlled by an electric signal, The dye is sublimated and transferred to the image receiving layer, and desired characters, images, etc. are formed on the image receiving layer.

The sublimation type thermal transfer system can reproduce a natural image relatively faithfully because the density gradation can be freely adjusted by using a sublimation type dye.
As the thermal transfer image receiving sheet used for the image formation, a solvent type thermal transfer image receiving sheet having a solvent type dye receiving layer and an aqueous type thermal transfer image receiving sheet having an aqueous dye receiving layer are known. Further, as a thermal transfer sheet used for the image formation, a thermal transfer sheet in which a primer layer for improving the adhesion between the base material and the dye layer is provided between the base material and the dye layer is known. .. (For example, Patent Document 1)

By the way, when printing is performed using the thermal transfer sheet as described above, when the triboelectric charge between the dye layer of the thermal transfer sheet and the thermal transfer image receiving sheet is large, the dye of the thermal transfer sheet is dyed during the initial operation of the printer. The layer and the thermal transfer image-receiving sheet may stick to each other, causing a problem that the thermal transfer sheet is caught in the printer (hereinafter, this problem is referred to as JAM).

Since the occurrence of JAM due to frictional electrification between the dye layer of the thermal transfer sheet and the thermal transfer image receiving sheet causes a great trouble at the initial operation of the printer, friction between the dye layer of the thermal transfer sheet and the thermal transfer image receiving sheet is caused. It is very important to reduce the charge. In other words, it is important to bring the dye layer of the thermal transfer sheet and the dye receiving layer of the thermal transfer image receiving sheet close to the triboelectric series.
The triboelectrification sequence is a permutation in which those that are more likely to be charged on the positive side are on the upper side, and those that are more likely to be charged on the negative side are arranged on the lower side. The larger the value, the larger the triboelectric charge. On the other hand, the smaller the difference in the triboelectrification sequence between the dye layer and the dye receiving layer, the smaller the triboelectrification.

JP, 2010-194881, A

The present invention has been made based on such circumstances, and it is an object of the present invention to provide a sublimable thermal transfer image-receiving sheet which can prevent the occurrence of JAM during the initial operation of a printer and can maintain a high gradation print density. To aim.

In order to solve the above problems, the first invention of the present invention is
A sublimable thermal transfer image-receiving sheet comprising at least an image receiving layer on one side of a support, and at least a back layer on the other side of the support,
The image receiving layer contains as a main component a vinyl-based copolymer emulsion containing at least vinyl chloride as a resin component,
Further, the sublimable thermal transfer image-receiving sheet is characterized in that the atomic ratio (Cl/C) of surface chlorine (Cl) to surface carbon (C) of the image receiving layer is 15% or more and 25% or less.

The second invention is
The sublimable thermal transfer image-receiving sheet according to claim 1, wherein the vinyl-based copolymer emulsion is used alone or as a mixture of two or more kinds.

The third invention is
The sublimable thermal transfer image-receiving sheet according to claim 1 or 2, further comprising an adhesive layer, a heat insulating layer, and a base layer between the support and the image receiving layer.

The sublimable thermal transfer image-receiving sheet according to the present invention contains a vinyl-based copolymer emulsion containing chlorine as an image-receiving layer as a main component, so that the dyeing property of the dye of the sublimation-type thermal transfer sheet is particularly strong and a high color density is obtained. Be done. Further, since the atomic ratio of surface chlorine to surface carbon of the image receiving layer is 15% or more and 25% or less, the difference in the triboelectrification train between the dye layer of the thermal transfer sheet and the image receiving layer of the image receiving sheet is small, and JAM occurs. The effect of preventing is great.

FIG. 1 is a sectional view of a specific example of the sublimable thermal transfer image-receiving sheet of the present invention.

Hereinafter, the present invention will be described with reference to the drawings. As described above, the sublimable thermal transfer image-receiving sheet of the present invention is one in which a sublimation type thermal transfer sheet is superposed thereon to form a transferred image.
FIG. 1 shows a specific example of the sublimable thermal transfer image-receiving sheet of the present invention. However, the present invention is not limited to the configuration of this case.

As shown in FIG. 1, the sublimable thermal transfer image-receiving sheet of the present invention comprises an adhesive layer (40 ), a heat insulating layer (30 ), a base layer (20 ), and an image receiving layer ( 10) in this order, and has an adhesive layer (60) and a back layer (70) on the other surface of the support.

(Support)
Examples of the material of the support (50) include condenser paper, glassine paper, sulfuric acid paper, synthetic paper (polyolefin-based and polystyrene-based), high-quality paper, art paper, coated paper, resin-coated paper, cast-coated paper, wallpaper, Backing paper, synthetic resin or emulsion impregnated paper, synthetic rubber latex impregnated paper, synthetic resin internal paper, paperboard, paper such as cellulose fiber paper, polyester, polyacrylate, polycarbonate, polyurethane, polyimide, polyetherimide, cellulose derivative, polyethylene , Ethylene-vinyl acetate copolymer, polypropylene, polystyrene, acrylic, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl butyral, nylon, polyether ether ketone, polysulfone, polyether sulfone, tetrafluoroethylene, perfluoroalkyl Examples thereof include films of vinyl ether, polyvinyl fluoride, tetrafluoroethylene.ethylene, tetrafluoroethylene.hexafluoropropylene, polychlorotrifluoroethylene, polyvinylidene fluoride, and the like. The thickness is not particularly limited, and for example, 90 to 170 μm is preferably used.

(Adhesive layer)
As a material used for the adhesive layers (40) and (60), conventionally known materials can be used. For example, polyolefin resin such as polyethylene, urethane resin, acrylic resin, polyester resin, epoxy resin, phenol resin. Resins, vinyl acetate resins, etc. can be used. Among them, polyethylene, urethane-based resin and acrylic resin are preferable.

(Insulation layer)
The heat insulating layer (30) has a role of making printing pressure uniform and preventing print leakage and uneven density during thermal transfer. As the material of the heat insulating layer (30), for example, polypropylene that is foamed to form microvoids can be used.

(Underlayer)
As the underlayer (20) provided between the heat insulating layer (30) and the image receiving layer (10), a conventionally known layer can be used. From the viewpoint of the adhesion to the heat insulating layer (30) and the image receiving layer (10) forming the interface, and the preservability of the printed matter, it is preferable to form an emulsion of a hydrophobic resin and a hydrophilic resin by coating and drying. ..

Examples of the hydrophobic resin include polyolefin resin, polyester resin, polyvinyl resin, polyurethane resin, polyacrylic acid resin, and copolymers of these resins. These may be used alone or in combination of two or more.

Examples of the hydrophilic resin include gelatin, water-soluble polyester, polyvinyl alcohol, polyvinylpyrrolidone, and the like.

(Image receiving layer)
Next, the image receiving layer (10) is a layer for forming a transferred image by dyeing a sublimable dye contained in the colored ink layer of the sublimation type thermal transfer sheet.
The image-receiving layer (10) used in the present invention contains at least a vinyl chloride-based copolymer containing vinyl chloride as a first component, and the ratio of the amount of surface chlorine atoms to the amount of surface carbon atoms is 15% or more and 25% or less. It is characterized by being.

The reason why the vinyl chloride copolymer is used here is that it contains chlorine, and in particular, the chlorine atom has a high electronegativity and has a strong dyeing property with the sublimable dye, so that a high coloring density is obtained. Is obtained. The details of the vinyl chloride copolymer will be described later.

Therefore, when the ratio of surface chlorine atoms to surface carbon atoms of the image receiving layer (10) is less than 15%, the print density at the highest gradation cannot be sufficiently obtained.

Further, generally, the triboelectrification column of the dye layer of the thermal transfer sheet is located on the plus side, and the triboelectrification column of the thermal transfer image receiving sheet is located on the minus side. The magnitude of triboelectrification has a close relationship with the difference between the triboelectrification sequences, and the larger the difference between the triboelectrification sequences, the greater the triboelectrification. As the triboelectric charge increases, JAM is likely to occur during the initial operation of the printer.

The thermal transfer image-receiving sheet having an image-receiving layer (10) containing a vinyl chloride emulsion as a main component, which is used in the present invention, has an advantage of being capable of maintaining a high gradation color density, while mainly containing an acrylic resin. The triboelectric charge train is located on the negative side of the image receiving layer as a component.

Therefore, when the ratio of the surface chlorine atom amount to the surface carbon atom amount of the image receiving layer (10) is larger than 25%, the triboelectric charge between the dye layer of the thermal transfer sheet and the thermal transfer image receiving sheet becomes large, and the printer during initial operation of the printer is The occurrence of JAM cannot be prevented.

As the binder resin for the image receiving layer (10), a vinyl copolymer emulsion containing a carboxy group, an acetyl group or both groups can be applied.
Examples of vinyl copolymer emulsions include vinyl chloride-acrylic copolymer, vinyl chloride-vinyl acetate copolymer, vinyl acetate-acrylic copolymer, styrene-acrylic copolymer, vinyl chloride-acrylic-ethylene copolymer. , Vinyl chloride-acrylic-styrene copolymer and the like.

The vinyl copolymer emulsion used in the thermal transfer image-receiving sheet of the present invention may have a copolymer containing at least vinyl chloride as the first component, and these may be used alone or in combination of two or more. By using these vinyl-based copolymer emulsions as the main component of the image receiving layer (10), it is possible to provide a thermal transfer image receiving sheet having both excellent releasability at the time of printing and retention of high gradation color density.

These vinyl copolymer emulsions, which are a single type or a mixture of two or more types, contain vinyl chloride as a first component of the resin component, and from the viewpoint of maintaining a high gradation color density, the surface chlorine atom is quantitatively compared with the surface chlorine atom. The ratio is 15% or more, and from the viewpoint of JAM during the initial operation of the printer, the quantitative ratio of surface chlorine atoms to surface carbon atoms needs to be 25% or less.

As the vinyl chloride emulsion, an emulsion commercially available from Nisshin Chemical Co., Ltd. can be used. For example, they are Viny Blanc 690, Viny Blanc 737, Viny Blanc 757, Viny Blanc 900, Viny Blanc 902, Viny Blanc 985, and the like.

Next, examples of the release agent include silicone release agents and fluorine-based release agents. Among them, a silicone release agent can be preferably used. For example, KF351A, KF352A, KF353, KF354L, KF355A, KF615A, KF945 (above, manufactured by Shin-Etsu Chemical Co., Ltd.).

(Back layer)
Next, the back surface layer (70) is provided for the purpose of imparting back surface-related performances such as writing performance, sizing performance, and loosening performance.
The back surface layer (70) may be composed of, for example, a binder resin. As the binder resin, conventionally known ones can be used, and examples thereof include styrene/acrylic resin, polyester resin, polyurethane resin, acrylic resin and the like. Further, as the back layer (70), a plastic film such as a polyethylene film, a polypropylene film, or a polyester film may be used.
Further, known additives such as a filler and an antistatic agent may be contained if necessary. The thickness of the back surface layer (70) is not particularly limited and may be, for example, 1 to 30 μm.

(Sublimation type thermal transfer sheet)
Next, a sublimation type thermal transfer sheet used for thermal transfer will be described. The sublimation type thermal transfer sheet is formed by printing a colored ink layer containing a sublimable dye, a yellow ink layer, a magenta ink layer, a cyan ink layer, or any one of the layers on a thermal transfer sheet substrate. is there.
By superposing this sublimation type thermal transfer sheet on the thermal transfer image receiving sheet and heating from the backside of the sublimation type thermal transfer sheet with a thermal head, the dye in the ink sublimes and is dyed on the image receiving layer (10). By controlling the heat generation energy of the thermal head, it is possible to control the amount of dye sublimated from the ink, and it is possible to form a transfer image with light and shade depending on the amount of this dye.

Hereinafter, the present invention will be described with reference to Examples and Comparative Examples.
The thermal transfer image-receiving sheets of the following Examples and Comparative Examples all have the layer structure shown in FIG. The term “part” in the text is based on mass unless otherwise specified, and the present invention is not limited to the examples.

(Example 1)
Paper (NATURAL manufactured by Nippon Paper Industries Co., Ltd.) was used as a support, and a biaxially stretched polyester film (Lumirror S10 manufactured by Toray Industries, Inc., thickness 18 μm) was laminated on one surface of the support to form a back layer. In addition, the paper and the biaxially stretched polyester film were formed by melt extruding low-density polyethylene between the two and laminating them by the adhesive force.

Next, a commercially available plastic sheet having microvoids was attached to the surface of the substrate opposite to the back layer as a heat insulating layer. The low density polyethylene was melt extruded between the paper and the heat insulating layer, and the paper and the heat insulating layer were bonded together by the adhesive force.

Next, a coating liquid containing water-based urethane and gelatin was applied to the surface of the polypropylene sheet (heat insulating layer) to form a base layer. The underlayer was formed to have a thickness of 1 μm.

Next, the image receiving layer was applied by the reverse gravure coating method to manufacture the thermal transfer image receiving sheet of Example 1. The coating amount of the image receiving layer was 2.0 g/m ² (dry), and the thickness when dried was 2.0 μm. Therefore, the thickness including the underlayer and the image receiving layer is formed to be 3.0 μm. The following materials were used for the image-receiving layer coating liquid. The compounding amount of the release agent is 7% by weight of the solid content of the vinyl emulsion, but is not particularly limited.
Vinyl chloride emulsion 70 parts (Vini Blanc 985 Nisshin Chemical Co., Ltd.)
Acrylic aqueous solution 30 parts (Vini Blanc 700, manufactured by Nissin Chemical Co., Ltd.)
Mold release agent 7 parts (KF352A manufactured by Shin-Etsu Chemical Co., Ltd.)

(Example 2, Comparative Example 1, Comparative Example 2)
Similarly, the ratio of the vinyl chloride emulsion and the acrylic aqueous solution of the image receiving layers of Example 2 and Comparative Examples 1 to 2 was adjusted according to the following Table 1 and applied.
Items other than the following Table 1 are the same as the procedure of Example 1.

(Sublimation type thermal transfer sheet)
Sublimation type thermal transfer sheets used for evaluation of the thermal transfer image receiving sheets of Examples 1 and 2 and Comparative Examples 1 and 2 were manufactured as follows.

First, a 4.5 μm-thick polyester film was used as a heat transfer sheet base material, a primer layer was formed on the surface of the heat transfer sheet base material, and a heat resistant slipping layer was further formed on the back surface. Next, an ink containing a sublimable dye of each color was printed to form a yellow ink layer, a magenta ink layer, and a cyan ink layer in a frame order. Then, a release layer and an adhesive layer were arranged and printed on each of the colored ink layers to form a protective layer, thereby producing a sublimation type thermal transfer sheet.
The release layer was printed on the exposed portion of the thermal transfer sheet substrate without each colored ink layer, and the protective layer was aligned with the release layer and printed on top of it.

(Print density of transfer image)
The sublimation type thermal transfer sheet was overlaid on each of the thermal transfer image receiving sheets of Examples 1 and 2 and Comparative Examples 1 and 2, and a V step image was printed by using a CX printer (sublimation transfer printer manufactured by Citizen Systems Co., Ltd.).

With respect to the transferred image thus formed, the spectrophotometer (IliO2, manufactured by Xrite) was used to measure the V density of the high gradation (255 gradation) printing portion to measure the optical density.
When the optical density was 1.90 or more, the reproducibility of colors of natural images and human skin was sufficiently secured, and it was judged to be good “◯”. On the other hand, when the optical density did not satisfy the above numerical range, it was judged that the dye density in the high gradation part was not sufficiently secured and the defect was “x”.

(JAM evaluation)
A CX printer (sublimation transfer printer manufactured by Citizen Systems Co., Ltd.) was set with the sublimation type thermal transfer sheet on each of the thermal transfer image receiving sheets of Examples 1 and 2 and Comparative Examples 1 and 2, and JAM was generated in the initial operation state of the printer. Was evaluated. When the initial operation was normally performed, it was determined to be “◯”. On the other hand, when the thermal transfer sheet was stuck and wound around the thermal transfer image receiving sheet during the initial operation, it was judged as “x”, which means that JAM occurred.

(Measurement of element amount)
It measured with the XPS (ESCA1600 ULVAC PHI company make) analyzer. As the measurement conditions, the amount of all elements on the surface of the image receiving layer was measured using a non-monochromatic X-ray, a measurement area of 0.8 mmφ, and a Mg target, and the atomic ratio (%) of Si, Cl, C, and O was calculated.

The evaluation results are shown in Table 2.

From this result, if the ratio of the amount of surface chlorine atoms to the amount of surface carbon atoms of the image receiving layer is less than 15%, a high gradation color density cannot be secured, while the ratio of the amount of surface chlorine atoms to the surface carbon atom amount of the image receiving layer is 25%. If it is larger than %, JAM cannot be suppressed.

From the above, as described in the present invention, when the ratio of the amount of surface chlorine atoms to the amount of surface carbon atoms of the image receiving layer is 15% or more and 25% or less, it is possible to prevent JAM from occurring during the initial operation of the printer, and to sublimate the same. When a transfer image is formed on the image receiving layer by stacking the mold thermal transfer sheets, the printing density of the highest gradation can be maintained.

10 Image Receiving Layer 20 Underlayer 30 Heat Insulating Layer 40 Adhesive Layer 50 Support 60 Adhesive Layer 70 Back Layer 100 Sublimable Thermal Transfer Image Receiving Sheet

Claims (3)

A sublimable thermal transfer image-receiving sheet comprising at least an image receiving layer on one side of a support, and at least a back layer on the other side of the support,
The image receiving layer contains as a main component a vinyl-based copolymer emulsion containing at least vinyl chloride as a resin component,
A sublimable thermal transfer image-receiving sheet, wherein the atomic ratio (Cl/C) of surface chlorine (Cl) to surface carbon (C) of the image receiving layer is 15% or more and 25% or less. The sublimable thermal transfer image-receiving sheet according to claim 1, wherein the vinyl-based copolymer emulsion is used singly or as a mixture of plural kinds. The sublimable thermal transfer image-receiving sheet according to claim 1 or 2, further comprising an adhesive layer, a heat insulating layer, and a base layer between the support and the image receiving layer.

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