JP7157373B2 - heat transfer sheet - Google Patents

Description

The present invention relates to thermal transfer sheets.

Conventionally, a thermal transfer sheet and a transfer-receiving material are combined to conceal the base color of the transfer-receiving material prior to forming a thermal transfer image on the transfer-receiving material. For example, when using a transfer-receiving material whose base color (also called background color) is not white, a single layer containing a white layer on the transfer-receiving material, or a transfer layer having a laminated structure ( (hereinafter referred to as a white transfer layer) is transferred to conceal the underlying color of the transferred material. Also, a white image (for example, characters, bar codes, etc.) is formed by transferring a white transfer layer onto a transfer material whose base color is not white. For example, in Patent Document 1, a colored layer is provided on a substrate, and a binder resin, titanium oxide, zinc oxide, silica, aluminum hydroxide, talc, clay, and kaolinite are added to the colored layer. Thermal transfer sheets provided with one or more white masking layers have been proposed. According to the thermal transfer sheet proposed in Patent Document 1, by transferring the white masking layer together with the colored layer onto the transferred material, the original hue of the colored layer can be reproduced on the transferred material, resulting in clear recording. is said to be possible.

By the way, when the white transfer layer is used for the purpose of concealing the background color of the transfer material or for the purpose of forming a white image on the transfer layer whose background color is not white, the white transfer layer is used as the background color of the transfer material. It is required to have sufficient white density without being affected by color. Further, when a white image is formed by transferring the white transfer layer, the white transfer layer is required to have good foil tearability so as to suppress the occurrence of tailing, crushing, and the like in the formed white image.

JP-A-2003-80847

SUMMARY OF THE INVENTION The main object of the present invention is to provide a thermal transfer sheet in which the white density of the transfer layer can be increased and the foil tearability of the transfer layer is good.

A thermal transfer sheet according to an embodiment of the present disclosure for solving the above problems is a thermal transfer sheet having a substrate and a transfer layer provided detachably from the substrate, wherein the transfer layer is at least melted wherein the molten layer contains titanium oxide having an oil absorption of 21 g/100 g or more and 40 g/100 g or less and a vinyl chloride-vinyl acetate copolymer; The content of titanium oxide having an oil absorption of 21 g/100 g or more and 40 g/100 g or less is 50% by mass or more, and the thickness of the molten layer is 2.1 μm or less.

In the above thermal transfer sheet, the vinyl chloride-vinyl acetate copolymer may be a vinyl chloride-vinyl acetate copolymer having a vinyl chloride monomer mass ratio of 91% by mass or more and less than 100% by mass . Further, the vinyl chloride-vinyl acetate copolymer may be a vinyl chloride-vinyl acetate copolymer containing a vinyl alcohol monomer and having a mass ratio of the vinyl alcohol monomer of more than 0% by mass and not more than 10% by mass. .

According to the thermal transfer sheet according to the embodiment of the present disclosure, the white density of the transfer layer can be increased, and the foil tearability of the transfer layer can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional schematic diagram which shows an example of the thermal transfer sheet of this indication. BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional schematic diagram which shows an example of the thermal transfer sheet of this indication. BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional schematic diagram which shows an example of the thermal transfer sheet of this indication. BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional schematic diagram which shows an example of the thermal transfer sheet of this indication. FIG. 4 is a front view showing evaluation patterns of printed matter of each example and comparative example.

Hereinafter, the present invention will be described with reference to the drawings. It should be noted that the present invention can be implemented in many different modes and should not be construed as being limited to the description of the embodiments exemplified below. In addition, in order to make the description clearer, the drawings may schematically show the width, thickness, shape, etc. of each part compared to the actual embodiment, but this is only an example, and the interpretation of the present invention is not intended. It is not limited. Further, in the specification and each figure of the present application, the same reference numerals may be given to the same elements as those described above with respect to the already-appearing figures, and detailed description thereof may be omitted as appropriate.

<<Thermal transfer sheet>>
As shown in FIGS. 1 to 4, the thermal transfer sheet 100 according to the embodiment of the present disclosure (hereinafter referred to as the thermal transfer sheet of the present disclosure) includes a substrate 1, and is provided on the substrate 1. It has a transfer layer 10 that can be peeled off from the material 1 side. Hereinafter, each configuration of the thermal transfer sheet 100 of the present disclosure will be specifically described with an example.

(Base material)
The base material 1 is an essential component in the thermal transfer sheet 100 of the present disclosure, and holds the transfer layer 10 and the like. The material of the base material 1 is not limited, and preferably has heat resistance and mechanical properties. Examples of such a substrate 1 include polyester such as polyethylene terephthalate, polycarbonate, polyimide, polyetherimide, cellulose derivatives, polyethylene, polypropylene, polystyrene, acrylic resin, polyvinyl chloride, polyvinylidene chloride, nylon, polyether ether ketone, and the like. Various plastic films or sheets can be exemplified. The thickness of the base material 1 can be appropriately set according to the material of the base material 1 so that its strength and heat resistance are appropriate, and is generally 2.5 μm or more and 100 μm or less.

Further, when another arbitrary layer is provided between the base material 1 and the transfer layer 10, for example, when the release layer 2 is provided between the base material 1 and the transfer layer 10 (FIG. 4 ), the surface of the substrate 1 on the side of the transfer layer 10 may be surface-treated in order to improve the adhesion between the substrate 1 and any other layer. Examples of surface treatment methods include corona discharge treatment, flame treatment, ozone treatment, ultraviolet treatment, radiation treatment, roughening treatment, chemical treatment, plasma treatment, low-temperature plasma treatment, primer treatment, and grafting treatment.

(transfer layer)
As shown in FIGS. 1 to 4, a transfer layer 10 is provided on the substrate 1. FIG. The transfer layer 10 is a layer that is peeled off from the substrate 1 by application of energy and migrates onto a transfer target. The transfer layer 10 may be provided directly on the base material 1 (see FIGS. 1 to 3), or may be provided indirectly via another layer (for example, the release layer 2). (See Figure 4). In the thermal transfer sheet 100 shown in FIG. 1, the transfer layer 10 has a single-layer structure consisting of only the melt layer 6. In the thermal transfer sheets 100 shown in FIGS. 6 presents a laminated structure.

In explaining the superiority of the thermal transfer sheet 100 of the present disclosure, the foil cutability of the melted layer (transfer layer including the melted layer) when the melted layer exhibiting a white color is transferred onto the transfer target, and the melting The relationship with the white density of the layer will be described.

Examples of means for increasing the white density of the melted layer transferred onto the transferred material include means for increasing the content of the white colorant contained in the melted layer and means for increasing the thickness of the melted layer. can. By the way, the thickness of the molten layer is closely related to the foil tearability when transferring the molten layer, and as the thickness of the molten layer increases, the foil tearability when transferring the molten layer increases. becomes lower. If the melted layer does not have sufficient foil tearability, when the melted layer is transferred to form letters or the like, trailing or crushed letters are likely to occur. The term "tailing" as used herein means that, when the melted layer is transferred onto the object to be transferred, the melted layer starts from the boundary between the transfer region and the non-transferred region of the melted layer and protrudes from the boundary toward the non-transferred region. It means the phenomenon of being transferred. In addition, character collapse means a phenomenon in which a region to be transferred surrounded or sandwiched by a transfer region represented as a character is transferred by a phenomenon similar to tailing, and the original character cannot be reproduced. .

In addition, when the thickness of the melted layer is reduced to a thickness at which the foil cutting property is good, even if the content of the white coloring agent contained in the melted layer is increased, the melted layer has a sufficient white color. Concentration cannot be given. In other words, there is a trade-off relationship between improving the foil tearability when transferring the white melted layer and imparting a sufficient white density to the melted layer.

(Molten layer)
Therefore, in the thermal transfer sheet 100 of the present disclosure, the melt layer 6 constituting the transfer layer 10 contains titanium oxide having an oil absorption of 20 g/100 g or more and a vinyl chloride-vinyl acetate copolymer. The content of titanium oxide having an oil absorption of 20 g/100 g or more is defined as 50% by mass or more, and the thickness of the molten layer 6 is defined as 2.1 μm or less. The oil absorption of titanium oxide as used herein is the oil absorption measured by a method conforming to JIS-K5101-13-1 (2004).

According to the thermal transfer sheet 100 of the present disclosure including such a melted layer 6, the foil tearability when transferring the transfer layer 10 including the melted layer 6 can be improved, and the white density of the melted layer 6 can be improved. can be high enough. As a result, when a predetermined image is formed by transferring the transfer layer 10 of the thermal transfer sheet 100 of the present disclosure, it is possible to prevent the image from being crushed or trailing. Furthermore, in the case of using a transfer-receiving material whose base color is not white, the transfer of the transfer layer 10 can conceal the base color. Also, an image or the like with high white density can be formed.

The thermal transfer sheet 100 of the present disclosure improves the white density of the melted layer 6 by using titanium oxide with an oil absorption of 20 g/100 g or more as a coloring agent, and by adjusting the content of this titanium oxide to By making it 50% by mass or more with respect to the total mass, the dry-hide effect can be exhibited, and as a result, the light diffusibility of the molten layer 6 is improved. As a result, even when the thickness of the transfer layer 10 is set to 2.1 μm or less in order to improve the foil tearability of the transfer layer 10 , a sufficient white density can be imparted to the melted layer 6 . When the thickness of the melted layer 6 is increased to more than 2.1 μm, the white density is good, but the foil tearability is deteriorated, and the transfer layer 10 including the melted layer 6 cannot be transferred. When an image or the like is formed by pressing, the image tends to be distorted or trailing.

Furthermore, in the thermal transfer sheet 100 of the present disclosure, a vinyl chloride-vinyl acetate copolymer is used as a binder component to be contained in the melt layer 6 together with the titanium oxide having an oil absorption of 20 g/100 g or more. can maintain a high white density. If another binder component is contained in place of the vinyl chloride-vinyl acetate copolymer, the white density of the melted layer is lowered, and a sufficient white density cannot be imparted to the melted layer.

In addition, since the vinyl chloride-vinyl acetate copolymer has adhesiveness, even when the melt layer 6 is positioned on the outermost surface of the transfer layer 10, for example, the transfer layer 10 can be separated from only the melt layer 6. Even if the transfer layer 10 has a single layer structure, or the transfer layer 10 has a laminated structure and the melting layer 6 is positioned farthest from the base material 1 among the layers constituting the transfer layer 10, Adhesion between the transferred body and the transfer layer 10 can be ensured when the transfer layer is transferred onto the transferred body.

Examples of titanium oxide having an oil absorption of 20 g/100 g or more include rutile-type titanium oxide whose surface is coated with aluminum oxide, silicon dioxide, zinc oxide, zirconium dioxide, or the like, or surface-treated. Alternatively, anatase-type titanium oxide may be used. Titanium oxide is not limited to surface-treated titanium oxide, and may be any material that satisfies the condition that the oil absorption is 20 g/100 g or more. The molten layer 6 may contain one type or two or more types of titanium oxide having an oil absorption of 20 g/100 g or more.

The average particle size of titanium oxide having an oil absorption of 20 g/100 g or more is not limited, and titanium oxide having an average particle size of 0.1 μm or more and 1 μm or less, titanium oxide having an average particle size of 0.2 μm or more and 0.3 μm or less, or the like can be used. The average particle size of titanium oxide as used herein is the volume average particle size (D50). The shape of titanium oxide is also not limited, and may be any shape.

The molten layer 6 preferably contains titanium oxide with an oil absorption of 22 g/100 g or more, more preferably contains titanium oxide with an oil absorption of 23 g/100 g or more, and an oil absorption of 25 g/100 g. It is more preferable to contain the above titanium oxide. By forming the molten layer 6 containing titanium oxide having a preferable oil absorption amount, the white density of the molten layer can be improved. There is no upper limit for the oil absorption, and examples include 80 g/100 g and 65 g/100 g.

The content of titanium oxide having an oil absorption of 20 g/100 g or more relative to the total mass of the molten layer 6 is more preferably 55% by mass or more, and even more preferably 75% by mass or more. In particular, it is preferable that titanium oxide having an oil absorption in the above preferred range is contained within this range.

The molten layer 6 may contain titanium oxide with an oil absorption of 20 g/100 g or more and titanium oxide with an oil absorption of less than 20 g/100 g. Moreover, you may contain white pigments other than a titanium oxide. In this case, the content of the white pigment different from titanium oxide and having an oil absorption of 20 g/100 g or more with respect to the total mass of the molten layer 6 is preferably 20% by mass or less.

The content of the vinyl chloride-vinyl acetate copolymer with respect to the total mass of the molten layer 6 is preferably 25% by mass or more and 55% by mass or less. By containing the vinyl chloride-vinyl acetate copolymer in this range, the durability of the melted layer 6 can be improved while improving foil tearability and sufficient white density. In other words, the durability of the transfer layer 10 including the melted layer 6 can be improved.

The melting layer 6 preferably contains a vinyl alcohol monomer (vinyl alcohol component) as a vinyl chloride-vinyl acetate copolymer, and the total weight of the vinyl chloride-vinyl acetate copolymer is 100% by weight. , the mass ratio (modification ratio) of the vinyl alcohol monomer is more preferably 10% by mass or less, and even more preferably 6% by mass or less. The melt layer 6 is composed of vinyl chloride having a vinyl chloride monomer (vinyl chloride component) mass ratio (modified ratio) of 91% by mass or more when the mass of the entire vinyl chloride-vinyl acetate copolymer is 100% by mass. - It preferably contains a vinyl acetate copolymer. Further, the molten layer 6 contains a vinyl alcohol monomer (vinyl alcohol component) as a vinyl chloride-vinyl acetate copolymer, and the vinyl chloride-vinyl acetate copolymer is 100% by mass. Contains a vinyl chloride-vinyl acetate copolymer having a monomer (vinyl chloride component) mass ratio (modification ratio) of 91% by mass or more and a vinyl alcohol monomer mass ratio (modification ratio) of 6% by mass or less. is particularly preferred. By setting the modification ratios of the vinyl alcohol component and the vinyl chloride component within the preferable ranges, it is possible to impart a higher white density to the melted layer 6 .

Further, the melt layer 6 may contain a resin component different from the vinyl chloride-vinyl acetate copolymer together with the vinyl chloride-vinyl acetate copolymer. In this case, the content of the vinyl chloride-vinyl acetate copolymer with respect to the total mass of the resin components (including the vinyl chloride-vinyl acetate copolymer) contained in the molten layer 6 is preferably 55% by mass or more. 65% by mass or more is more preferable.

The thickness of the molten layer 6 is preferably 0.8 μm or more and 2 μm or less, more preferably 1.2 μm or more and 2 μm or less. By setting the thickness of the molten layer to a preferable thickness, the durability of the molten layer 6 can be improved.

The method of forming the molten layer is not limited, and titanium oxide having an oil absorption of 20 g/100 g or more, vinyl chloride-vinyl acetate copolymer, and various additives added as necessary are dispersed or dissolved in an appropriate solvent. A molten layer coating solution is prepared, and this coating solution is applied to the substrate 1 or any layer provided on the substrate 1 so that the thickness after drying is 2.1 μm or less.・Can be formed by drying. The coating method includes, for example, a gravure printing method, a screen printing method, a reverse coating method using a gravure plate, and the like. Other coating methods may also be used. This also applies to methods for applying various coating liquids, which will be described later.

(Release layer)
Alternatively, as shown in FIG. 2, the transfer layer 10 may have a laminated structure in which the release layer 4 and the melt layer 6 are laminated in this order from the substrate 1 side. According to the transfer layer 10 having the configuration shown in FIG. 2, the transferability can be improved when the transfer layer 10 is transferred onto the transferred body.

Resin components of the release layer include ethylene-vinyl acetate copolymer, vinyl chloride-vinyl acetate copolymer, maleic acid-modified vinyl chloride-vinyl acetate copolymer, polyamide, polyester, polyethylene, and ethylene-isobutyl acrylate copolymer. , butyral, polyvinyl acetate and its copolymer, ionomer resin, acid-modified polyolefin, acrylic, methacrylic (meth)acrylic resin, acrylic acid ester resin, ethylene-(meth)acrylic acid copolymer, ethylene - (Meth) acrylic acid ester copolymer, polymethyl methacrylate, cellulose resin, polyvinyl ether, polyurethane, polycarbonate, polypropylene, epoxy resin, phenolic resin, vinyl resin, maleic acid resin, alkyd resin, polyethylene oxide, urea resin, melamine Resin, melamine-alkyd resin, silicone resin, rubber resin, styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene-butylene-styrene block copolymer Examples include coalescence (SEBS), styrene-ethylene-propylene-styrene block copolymer (SEPS), and the like.

The thickness of the release layer is not particularly limited, but is preferably 0.1 μm or more and 15 μm or less, more preferably 0.3 μm or more and 3 μm or less.

(adhesion layer)
Further, as shown in FIG. 3, the transfer layer 10 may have a laminated structure in which the melt layer 6 and the adhesive layer 7 are laminated in this order from the substrate 1 side. According to the transfer layer 10 having the configuration shown in FIG. 3, the adhesion between the transfer layer 10 and the transfer medium can be improved when the transfer layer 10 is transferred to the transfer medium. Alternatively, the transfer layer 10 may have a laminate structure in which the release layer 4, the melt layer 6, and the adhesive layer 7 are laminated in this order from the substrate 1 side.

Components of the adhesive layer include polyurethane, α-olefin-polyolefin such as maleic anhydride, polyester, acrylic, epoxy resin, urea resin, melamine resin, phenol resin, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, cyano Resin components such as acrylate can be exemplified. Moreover, you may use what hardened these components with the hardening|curing agent. Examples of curing agents include isocyanate compounds, aliphatic amines, cycloaliphatic amines, aromatic amines, and acid anhydrides. Also, the adhesive layer may contain molybdenum disulfide.

The thickness of the adhesive layer is preferably 0.3 μm or more and 10 μm or less, more preferably 0.5 μm or more and 2 μm or less. For the adhesive layer, a coating liquid for the adhesive layer is prepared by dispersing or dissolving the components exemplified above in an appropriate solvent, and this coating liquid is optionally provided on the melted layer 6 or on the melted layer 6. It can be formed by coating and drying on the layer to be formed.

(release layer)
Also, as shown in FIG. 4, a release layer 2 may be provided between the base material 1 and the transfer layer 10 . By providing the release layer 2, it is possible to improve the transferability when the transfer layer 10 is transferred onto the transferred material. The transfer layer 10 in the form shown in FIG. 4 may have a single layer structure consisting of only the melted layer 6 or may have a laminated structure including the melted layer 6 .

Components of the release layer include waxes, silicone waxes, silicone resins, various silicone-modified resins such as silicone-modified acrylic resins, fluororesins, fluorine-modified resins, polyvinyl alcohol, vinyl chloride-vinyl acetate copolymers, acrylic resins, Examples include thermally crosslinkable epoxy-amino copolymers, thermally crosslinkable alkyd-amino copolymers, melamine resins, cellulose resins, urea resins, polyolefins, cellulose resins, polyamides, lactic acid resins, and the like. The release layer may contain one component alone, or may contain two or more components. As an example, the thickness of the release layer is 0.1 μm or more and 1 μm or less.

(back layer)
Also, a back layer may be provided on the surface of the substrate 1 opposite to the surface on which the transfer layer 10 is located (not shown).

Components of the back layer include polyester, polyacrylate, polyvinyl acetate, acrylic-styrene copolymer, urethane resin, polyolefin such as polyethylene and polypropylene, polystyrene, polyvinyl chloride, polyether, polyamide, polyimide, and polyamideimide. , polycarbonate, polyacrylamide, polyvinyl chloride, polyvinyl acetals such as polyvinyl acetal and polyvinyl butyral, and resin components such as silicone modified products thereof. Among them, polyamideimide or its silicone modified product can be preferably used from the viewpoint of heat resistance and the like.

In addition, for the purpose of improving the slip property, the back layer may contain wax, higher fatty acid amide, phosphoric acid ester compound, metal soap, silicone oil, release agent such as surfactant, organic powder such as fluororesin, silica, clay, etc. , talc, and inorganic particles such as calcium carbonate.

For the back layer, for example, a back layer coating liquid is prepared by dispersing or dissolving the above components and various additives added as necessary in an appropriate solvent, and this coating liquid is applied to the base material. 1 by coating and drying. The thickness of the back layer is preferably 0.1 μm or more and 5 μm or less, more preferably 0.3 μm or more and 2 μm or less.

(colorant layer)
Further, a coloring material layer may be provided on the substrate 1 in a plane-sequential manner with the transfer layer 10 (not shown). The number of coloring material layers may be one, or a plurality thereof may be provided in a frame-sequential manner. For example, a yellow colorant layer, a magenta colorant layer, a cyan colorant layer, a black colorant layer, and the like may be sequentially provided. Further, when the coloring material layer and the transfer layer 10 are defined as "one unit", "one unit" can be repeatedly provided on the other surface of the substrate 1. FIG.

The material to which the transfer layer 10 of the thermal transfer sheet 100 of the present disclosure is transferred is mainly composed of plain paper, fine paper, tracing paper, plastic film, vinyl chloride, vinyl chloride-vinyl acetate copolymer, and polycarbonate. A plastic card or the like can be exemplified. Also, a material having a predetermined image can be used as the material to be transferred. A thermal transfer image receiving sheet can also be used as the transfer material. Moreover, you may use the transfer-receiving body other than this. The thermal transfer sheet 100 of the present disclosure is suitable for transferring a transfer layer onto a transfer material having a base color other than white.

For the transfer of the transfer layer 10 onto the object to be transferred, for example, a method using a heating device such as a thermal head, a hot stamp method, a heat roll method, or the like can be used. Also, other methods can be used.

In the specification of the present application, the resins and the like constituting each layer are exemplified, but these resins may be homopolymers of the monomers constituting each resin. It may be a copolymer of a main component monomer and one or more other monomers, or a derivative thereof. For example, in the case of an acrylic resin, it may contain acrylic acid or methacrylic acid monomers or acrylic acid ester or methacrylic acid ester monomers as main components. Modified products of these resins may also be used. Resins other than those exemplified herein may also be used.

EXAMPLES Next, the present invention will be described more specifically with reference to examples and comparative examples. Hereinafter, parts and % are based on mass unless otherwise specified.

(Example 1)
A PET (polyethylene terephthalate) film having a thickness of 4.5 μm was used as a substrate, and a release layer coating solution having the following composition was applied to one surface of the substrate and dried to form a film having a thickness of 1 μm. A release layer was formed. Next, a melt layer coating solution 1 having the following composition was applied onto the release layer and dried to form a melt layer having a thickness of 1.2 μm. On the other side of the substrate, a back layer coating liquid having the following composition is applied and dried to form a back layer having a thickness of 1 μm, thereby forming a release layer on one side of the substrate. , the melted layer were laminated in this order, and a back layer was provided on the other side to obtain the thermal transfer sheet of Example 1. The release layer and the melting layer constitute the transfer layer of the thermal transfer sheet of the present disclosure.

<Coating solution for release layer>
・Vinyl chloride-vinyl acetate copolymer 95 parts (Solbin (registered trademark) CNL Nissin Chemical Industry Co., Ltd.)
・ Polyester 5 parts (Vylon (registered trademark) 200 Toyobo Co., Ltd.)
・Methyl ethyl ketone 200 parts ・Toluene 200 parts

<Coating liquid 1 for molten layer>
・Vinyl chloride-vinyl acetate copolymer 25 parts (Solbin (registered trademark) AL Nissin Chemical Industry Co., Ltd.)
・ Titanium oxide 25 parts (R-780 Ishihara Sangyo Co., Ltd.)
・25 parts of methyl ethyl ketone ・25 parts of toluene

<Coating solution for back layer>
・ Polyvinyl butyral 70 parts (Slec (registered trademark) BX-1 Sekisui Chemical Co., Ltd.)
・ Polyisocyanate curing agent 15 parts (Takenate (registered trademark) D218 Mitsui Chemicals, Inc.)
・ Phosphate ester 15 parts (Plysurf (registered trademark) A208S Daiichi Kogyo Seiyaku Co., Ltd.)
・Methyl ethyl ketone 300 parts ・Toluene 300 parts

(Examples 2 to 18, Comparative Examples 1 to 7)
In the same manner as in Example 1, except that the molten layer coating liquid 1 was changed to the molten layer coating liquids 2 to 18 shown in Table 1 below to form a molten layer having a thickness shown in Table 1 below. , Examples 2 to 18, and Comparative Examples 1 to 7 were obtained. Table 2 shows the details of the binder and titanium oxide contained in the molten layer coating solution in Table 1. In each coating liquid, the amounts of methyl ethyl ketone and toluene as solvents are 25 parts each, and are omitted in Table 1.

(Manufacture of prints)
Using a black PVC card (Dai Nippon Printing Co., Ltd.) as a transfer material, the thermal transfer sheets of each example and comparative example are superimposed, and the transfer layers of the thermal transfer sheets of each example and comparative example are printed by the following test printer. was transferred in the evaluation pattern shown in FIG. Note that the white area in FIG. 5 is the transferred layer portion. The OD value of the black PVC card was 2.1, measured by spectrophotometer (RD918 X-Rite).

(test printer)
・Thermal head: KEE-57-12GAN2-STA (Kyocera Corporation)
・ Heating element average resistance value: 3303 (Ω)
・Main scanning direction print density: 300 (dpi)
・Sub-scanning direction print density: 300 (dpi)
・Line cycle: 3 (msec./line)
・Print start temperature: 35 (°C)
・Pulse duty ratio: 85 (%)
・Applied voltage: 20 (V)

(Evaluation of foil tearability)
Visually check the printed matter of each example and comparative example obtained using the thermal transfer sheet of each example and comparative example, and check whether there is any omission or blurred part in the evaluation pattern (barcode pattern). Then, evaluation of foil cutability was performed based on the following evaluation criteria. Table 3 shows the evaluation results.

"Evaluation criteria"
A: No omissions or blurring occurred in the evaluation pattern (barcode pattern).
NG: The evaluation pattern (barcode pattern) is missing or blurred.

(Concealability evaluation)
The OD value at the center of the evaluation pattern in the printed matter of each example and comparative example obtained using the thermal transfer sheet of each example and comparative example was measured from the transfer layer, and the hiding property was evaluated based on the following evaluation criteria. did The OD value was measured with a spectrophotometer (RD918 X-Rite). Table 3 shows the evaluation results. It should be noted that the smaller the OD value, the higher the concealability of the transfer layer.

"Evaluation criteria"
A: OD value less than 0.35.
B: OD value is 0.35 or more and less than 0.4.
C: OD value is 0.4 or more and less than 0.5.
D: OD value is 0.5 or more and less than 0.55.
NG: OD value is 0.55 or more.

(Abrasion resistance evaluation)
According to the Taber test method conforming to ANSI-INCITS322-2002, 5.9 Surface Abrasion, using a Taber tester, wear wheel CS-10F, load 500 gf, 60 cycles/min. , an abrasion test was performed on the central portion of the evaluation pattern in the printed matter produced above. Every 100 cycles, the reflection density of the worn portion was measured with a spectrophotometer (RD918, X-Rite), and the abrasion was terminated when the density reached 200% or more of the density before abrasion. The reflection density of the worn portion was plotted every 100 cycles, and the number of cycles at which the reflection density reached 200% or more of the density before abrasion was calculated from the approximate curve. Table 3 shows the calculated number of cycles. In addition, it means that wear resistance is so favorable that a cycle number is large.

DESCRIPTION OF SYMBOLS 1... Base material 2... Release layer 4... Release layer 6... Melting layer 7... Adhesive layer 10... Transfer layer 100... Thermal transfer sheet

Claims (3)

A thermal transfer sheet having a substrate and a transfer layer provided so as to be peelable from the substrate,
the transfer layer includes at least a melting layer;
The molten layer contains titanium oxide having an oil absorption of 21 g/100 g or more and 40 g/100 g or less and a vinyl chloride-vinyl acetate copolymer,
The content of titanium oxide having an oil absorption of 21 g/100 g or more and 40 g/100 g or less with respect to the total mass of the molten layer is 50% by mass or more,
The melted layer has a thickness of 2.1 μm or less,
Thermal transfer sheet. The vinyl chloride-vinyl acetate copolymer is a vinyl chloride-vinyl acetate copolymer having a vinyl chloride monomer mass ratio of 91% by mass or more and less than 100% by mass .
The thermal transfer sheet according to claim 1. The vinyl chloride-vinyl acetate copolymer is a vinyl chloride-vinyl acetate copolymer containing a vinyl alcohol monomer and having a mass ratio of the vinyl alcohol monomer of more than 0% by mass and not more than 10% by mass.
The thermal transfer sheet according to claim 1 or 2.

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