JP7701682B2 - Thermal transfer ink ribbon - Google Patents

Description

Applicable under Article 30, Paragraph 2 of the Patent Act. Shipped from Dainiku Co., Ltd.'s Saitama Factory on November 10, 2020.

The present invention relates to a thermal melt transfer ink ribbon which has excellent environmental preservation properties even in a high-temperature environment, excellent print quality, and good print sensitivity.

Thermal melt transfer ink ribbons, which have an ink layer containing at least a coloring component such as a pigment and a binder component such as various waxes or resins on a base film, are loaded into thermal transfer printers and are widely used in offices, factories, logistics warehouses, etc. for printing text information, barcodes, etc. on display labels, management labels, etc.

Thermal transfer printers are widely used in a variety of locations and environments because, compared to office printers, they have a simpler structure, are easier to maintain, are less prone to breakdowns, and can be made compact in size.

However, in particularly hot environments such as places where the air conditioning is not very effective in the summer or food production lines, simply installing a thermal transfer printer can cause problems with the environmental preservation performance of the thermal transfer ink ribbon, such as blocking occurring in the thermal transfer ink ribbon loaded inside the thermal transfer printer or deterioration of print quality due to softening or deformation of the ink layer or transfer control layer of the thermal transfer ink ribbon.

Furthermore, when continuous printing is performed using a thermal transfer printer in a high-temperature environment as described above, the heat generated during printing is not dissipated but accumulates in the thermal head, and this heat tends to cause a print quality problem called surface peeling in the printed image.

2, planar peeling refers to a print image 7b that is unevenly formed in a scale-like or wavy shape on the opposite side of the print image 7a that was originally intended to be formed in the conveying direction of the print medium 6, and while the print image 7a is firmly transferred and adhered to the print medium 6, the planar peeled portion 7b is not firmly or not adhered at all to the print medium 6 even if it is normally transferred. When this planar peeling occurs, not only does the appearance of the printed text or the like look bad, but in severe cases the text cannot be recognized, and in the case of printing barcodes or the like, not only does it cause problems in print quality such as poor reading of the barcode, but it also causes problems such as the planar peeled portion coming off and scattering, thereby polluting the print medium and the surrounding environment.

To explain an example of a general printing mechanism performed by a thermal transfer printer, the print-receiving medium 6 and the thermal melt transfer ink ribbon 1 are set in the thermal transfer printer while being sandwiched and pressed between the thermal head 8 and platen roll 9 of the thermal transfer printer, as shown in Fig. 3. During printing, the transfer control layer 4 and the ink layer 5 in the portion where the print image is to be formed are heated by the thermal head 8 to soften and melt, and after they wet or soak into the surface layer of the print-receiving medium 6 and then cooled and solidified to a certain extent, the thermal melt transfer ink ribbon 1 and the print-receiving medium 6 are peeled off, and a print image consisting of the transfer control layer 4 and the ink layer 5 is formed on the print-receiving medium 6.

During normal printing, the transfer control layer 4 and ink layer 5 between A and B in Figure 3 are overheated by the thermal head 8 and thoroughly softened and melted, causing delamination near the interface between the transfer control layer 4 and the base film 2, where the adhesive strength is weakest, and only the transfer control layer 4 and ink layer 5 between A and B in Figure 3 are transferred to the print medium 6, meaning that only the print image that was originally intended to be formed in part 7a in Figure 3 is formed.

However, when printing occurs in which planar peeling occurs, although the thermal head 8 only heats between A and B in Fig. 3, the heat accumulated in the thermal head 8 during printing for some reason causes at least the transfer control layer 4 near the base film 2 between B and C in Fig. 3 to soften and melt, but the ink layer 5 does not soften and melt, or the transfer control layer 4 and the ink layer 5 between B and C to soften and melt incompletely, causing a state in which the transfer control layer 4 and the ink layer 5 between B and C in Fig. 3 are pulled by the print image 7a that was originally intended to be formed, and a part of the transfer control layer 4 and the ink layer 5 between B and C in Fig. 3 are transferred as the print image 7b, which is the planar peeling part, when the thermal melt transfer ink ribbon 1 and the print-receiving medium 6 are peeled off. This part of the print image 7b is transferred in a state in which it is forcibly pulled by the part of the print image 7a, and since the transfer control layer 4 and the ink layer 5 are mechanically forcibly broken at the position C in Fig. 3, the broken surface is unevenly formed, such as scale-like or wavy. 3, the ink layer 5 between B and C is not softened or melted at all, or is only incompletely softened and melted, so although it is transferred to the transfer medium 6, it is not adhered at all, or is not adhered firmly. When such planar peeling occurs, it causes problems with print quality and contamination as described above, and therefore improvements have been required for some time.

In order to solve such problems, Patent Document 1 proposes a thermal melt transfer ink ribbon having a heat-resistant slipping layer on one side of a base film and a transfer control layer and an ink layer laminated in that order on the other side, in which the ink layer contains a thermoplastic resin having a glass transition point of 50°C or more and 110°C or less, and the transfer control layer contains 50% by mass or more of fine particles made of high-density polyethylene wax having a melting peak temperature of 110°C or more and 135°C or less and a temperature difference between the melting peak temperature and the extrapolated melting start temperature of within 10.0°C.

The use of the thermal melt transfer ink ribbon proposed in Patent Document 1 has excellent environmental preservation performance in high temperature environments, and furthermore, when printing is performed in a high temperature environment, surface peeling of the printed image is less likely to occur. On the other hand, however, if a large amount of thermoplastic resin with a relatively high glass transition point is added to the ink layer, or if a large amount of high-melting-point high-density polyethylene wax with specific melting characteristics is added as the main component of the transfer control layer, the printing sensitivity tends to deteriorate and the range of printing energy in which good printing quality can be maintained becomes relatively narrow. As a result, depending on the type of thermal transfer printer and the printing environment, problems such as smearing of the print may occur.

JP 2019-93696 A

The present invention has been made in consideration of the above-mentioned circumstances, and its main objective is to provide a thermal melt transfer type ink ribbon that has excellent environmental preservation performance in a high temperature environment, is less likely to cause surface peeling in the printed image when printing in a high temperature environment, and has good printing sensitivity.

In order to solve the above-mentioned problems, the present inventors have conducted studies and have found that by using a thermal melt transfer type ink ribbon having a heat-resistant slipping layer on one side of a base film and a transfer control layer and an ink layer laminated in this order on the other side, the ink layer contains a coloring component and a binder component, the binder component of the ink layer contains an ethylene copolymer resin having a melting peak temperature of 60° C. or more, aliphatic hydrocarbon synthetic wax fine particles having a melting peak temperature of 100° C. or more, and a tackifier resin, and the transfer control layer contains aliphatic hydrocarbon synthetic wax fine particles having a melting peak temperature of 100° C. or more in a range of 50% by mass to 95% by mass of the entire transfer control layer and a carboxylic acid modified polyolefin having a melting peak temperature of 100° C. or more in a range of 5% by mass to 50% by mass of the entire transfer control layer, the thermal melt transfer type ink ribbon has excellent environmental preservation performance in a high-temperature environment of 50° C., is less likely to cause surface peeling in a printed image when printed in a high-temperature environment of 40° C., and also has good printing sensitivity.

When the thermal melt transfer ink ribbon of the present invention is used, problems with environmental preservation performance, such as blocking phenomena and deterioration of print quality, are unlikely to occur even when stored in a high-temperature environment, and print quality problems, such as surface peeling in the printed image when printing in a high-temperature environment, are unlikely to occur. Furthermore, since the print sensitivity is good, problems due to print sensitivity are unlikely to occur even when used with various printers and in various environments.

FIG. 1 is a schematic cross-sectional view showing an example of an embodiment of a thermal melt transfer ink ribbon of the present invention. FIG. 4 is a schematic plan view of a printed image for explaining planar peeling. FIG. 2 is a schematic diagram of the thermal head periphery of a thermal transfer printer as viewed from the side to explain planar peeling.

As shown in FIG. 1, the thermal melt transfer ink ribbon 1 of the present invention has a structure in which a heat-resistant slipping layer 3 is provided on one side of a base film 2, and a transfer control layer 4 and an ink layer 5 are laminated in this order on the other side.

<<Components of Thermal Melt Transfer Ink Ribbon>>
Next, the components of the thermal melt transfer ink ribbon of the present invention will be described in detail below.

<Base film>
The substrate film used in the present invention is not particularly limited as long as it has a certain degree of heat resistance and strength, and can be appropriately selected from conventionally known materials. Examples of substrate films having such heat resistance include polyethylene terephthalate film (PET film), polypropylene film, polystyrene film, polyimide film, polyamide film, polycarbonate film, polyvinyl chloride film, etc., but it is most preferable to use polyethylene terephthalate film. The thickness of the substrate film is not particularly limited, but should be appropriately considered depending on the material so that the strength, heat resistance, and thermal conductivity are appropriate, and it is sufficient to be in the range of 2 μm to 12 μm, but more preferably in the range of 3 μm to 6 μm because of good thermal conductivity.

<Heat-resistant slippery layer>
The thermal melt transfer ink ribbon of the present invention has a heat-resistant slipping layer on one side of the substrate film (the side that comes into contact with the thermal head during printing) in order to prevent the substrate film from breaking, fusing to the thermal head, wrinkling, or accumulation of foreign matter on the thermal head due to the heat of the thermal head during printing, and to prevent the occurrence of a sticking phenomenon in which the slipperiness between the substrate film and the thermal head deteriorates. The heat-resistant slipping layer may be provided by applying a paint for the heat-resistant slipping layer to the substrate film using any of various known coating machines or the like, and then drying with a hot air dryer or the like, or may be provided simultaneously with the formation of the substrate film.

The raw materials used for the heat-resistant slipping layer of the present invention are not particularly limited, and may be selected appropriately and used according to the required quality from various known heat-resistant resins such as various silicone modified resins, fluorine-based resins, polyolefin-based resins, cellulose-based resins, and polyimide-based resins as main raw materials, various known adhesive resins (e.g., polyester-based resins, polyurethane-based resins, epoxy-based resins, etc.), various known crosslinking agents, various known lubricants (e.g., derivatives of higher fatty acids and their metal salts, various waxes, silicone oils, silicone resin powders, silicone rubber powders, liquid polyolefins, etc.), and various organic and inorganic fillers as other raw materials.

The coating amount of the heat-resistant slipping layer after drying is not particularly limited, and may be appropriately selected and determined from the range of 0.01 g/m ² or more and 0.50 g/m ² or less depending on the usage situation and the type of printer, etc., but from the viewpoint of cost and performance stability, the range of 0.05 g/m ² or more and 0.40 g/m ² or less is more preferable. If the coating amount of the heat-resistant slipping layer after drying is less than 0.01 g/m ² , the expected heat resistance effect cannot be obtained, and conversely, if the coating amount of the heat-resistant slipping layer after drying is 0.5 g/m ² or more, the sensitivity during printing tends to deteriorate, or a problem of foil falling, which is a phenomenon in which the heat-resistant slipping layer falls off the substrate film, tends to occur.

<Transfer Control Layer>
In the present invention, a transfer control layer is provided between the base film and the ink layer in order to control the peeling force between the base film and the ink layer, printing sharpness, etc. In addition to fulfilling the role of a normal transfer control layer, the transfer control layer of the present invention needs to be a transfer control layer that does not adversely affect environmental preservation performance in a high-temperature environment and further has the performance of suppressing the occurrence of planar peeling in the printed image when printing is performed in a high-temperature environment.

The present inventors have investigated heat-melting substances to be added to the transfer control layer to impart peelability in order to satisfy the above-mentioned performance, and as a result, it has been found that it is preferable to add a heat-melting substance that has a relatively high melting point, a sharp melting characteristic near the melting point, contains little impurities, and has very good releasability from other layers when melted. As a result of further examining such heat-melting substances, it has been found that it is most preferable to add an aliphatic hydrocarbon synthetic wax to the transfer control layer as a main component. Examples of the aliphatic hydrocarbon synthetic wax include polyethylene wax, polypropylene wax, olefin copolymers having a number average molecular weight of 10,000 or less (e.g., ethylene-polypropylene copolymer, ethylene-α-olefin copolymer, propylene-α-olefin copolymer), and Fischer-Tropsch wax. From the viewpoints of good printing sensitivity and releasability, and excellent effect of suppressing the occurrence of planar peeling in a printed image when printing is performed in a high-temperature environment, it is more preferable to add at least one of Fischer-Tropsch wax and polyethylene wax, and it is most preferable to add Fischer-Tropsch wax.

The aliphatic hydrocarbon synthetic wax added to the transfer control layer is preferably dispersed in the transfer control layer, since it is possible to more effectively prevent the occurrence of planar peeling in the printed image by improving the foil cutting property of the transfer control layer itself, and the aliphatic hydrocarbon synthetic wax added to the transfer control layer of the present invention is used in a state processed into fine particles. As such aliphatic hydrocarbon synthetic wax fine particles, it is preferable to use an emulsion or dispersion in which water is used as the main dispersion medium and the aliphatic hydrocarbon synthetic wax is dispersed in a fine particle state in the dispersion medium. By adding the aliphatic hydrocarbon synthetic wax dispersed in a fine particle state to the transfer control layer, it is possible to easily control the releasability between other layers during printing and to further improve the foil cutting property of the transfer control layer, and as a result, it is possible to more effectively prevent the occurrence of planar peeling in the printed image.

The average particle diameter of the aliphatic hydrocarbon synthetic wax microparticles is preferably in the range of 0.1 μm to 10.0 μm, more preferably in the range of 0.1 μm to 5.0 μm. If the average particle diameter of the aliphatic hydrocarbon synthetic wax microparticles is within the above range, not only can the occurrence of planar peeling in the printed image when printing is performed in a high temperature environment be effectively suppressed, but also the interface between the ink layer and the transfer control layer becomes moderately smooth, so that the peeling force between the ink layer and the transfer control layer becomes moderate, the transferability of the ink layer is good, and problems such as foil falling off of the ink layer tend to be unlikely to occur. The average particle diameter of the aliphatic hydrocarbon synthetic wax microparticles in the present invention is calculated by photographing the transfer control layer at a magnification of 10,000 times with an electron microscope, randomly selecting 20 aliphatic hydrocarbon synthetic wax microparticles from the photographed image, measuring the maximum diameter of each microparticle, and calculating the average.

Furthermore, the present inventors have investigated the thermal properties of the aliphatic hydrocarbon synthetic wax particles added to the transfer control layer, and found that the peak melting temperature (JIS K7121) of the aliphatic hydrocarbon synthetic wax particles measured by differential scanning calorimetry is preferably 100° C. or higher. As a result of their investigation, the present inventors have found that if the peak melting temperature of the aliphatic hydrocarbon synthetic wax particles is 100° C. or higher, the aliphatic hydrocarbon synthetic wax particles do not easily soften in a high-temperature environment of 50° C., and therefore softening and deformation of the transfer control layer itself can be suppressed, thereby improving environmental preservation performance in a high-temperature environment and simultaneously suppressing the occurrence of planar peeling in a printed image when printing is performed in a high-temperature environment of 40° C. On the other hand, when the melting peak temperature of the aliphatic hydrocarbon synthetic wax microparticles falls below 100°C, reverse transfer tends to occur easily during printing, and the transferability of the print tends to deteriorate. Furthermore, in a high-temperature environment of 50°C, the aliphatic hydrocarbon synthetic wax microparticles gradually begin to soften, and as a result, the transfer control layer tends to soften and deform, resulting in deterioration of environmental preservation performance. Furthermore, when printing is performed in a high-temperature environment, planar peeling tends to occur particularly easily in the printed image.

The upper limit of the melting peak temperature of the aliphatic hydrocarbon synthetic wax microparticles is not particularly limited, but from the viewpoint of printing sensitivity and transferability, it is preferably 140° C. or less, and more preferably 130° C. or less. Conversely, if the melting peak temperature of the aliphatic hydrocarbon synthetic wax microparticles exceeds the upper limit, a large amount of heat is required for printing, or the melt viscosity of the aliphatic hydrocarbon synthetic wax microparticles increases, gradually deteriorating the printing sensitivity and transferability of the print, which tends to narrow the printing energy range in which suitable printing can be performed with a thermal transfer printer, or to make it easier for problems such as blurred prints to occur in low-temperature environments.

The amount of the aliphatic hydrocarbon synthetic wax microparticles added to the transfer control layer is preferably at least 50% by mass or more of the entire transfer control layer, more preferably 65% by mass or more, and conversely, the upper limit of the amount added is preferably 95% by mass or less of the entire transfer control layer, more preferably 85% by mass or less. If the amount of the aliphatic hydrocarbon synthetic wax microparticles added is within the above range, the environmental preservation performance in a high-temperature environment is good, and it is possible to effectively suppress the occurrence of surface peeling of the printed image when printing is performed in a high-temperature environment. If the amount of the aliphatic hydrocarbon synthetic wax microparticles added is below the lower limit of the range, the environmental preservation performance in a high-temperature environment and the surface peeling of the printed image when printing is performed in a high-temperature environment tend to deteriorate, and conversely, if it exceeds the upper limit of the range, the adhesion to the base film is rapidly reduced, and therefore the surface peeling of the printed image when printing is performed in a high-temperature environment tends to deteriorate rapidly, and foil fall-off of the ink layer and the transfer control layer tends to occur easily.

The transfer control layer of the present invention contains aliphatic hydrocarbon synthetic wax microparticles, which are a heat-melting substance, as a main component, but with only aliphatic hydrocarbon synthetic wax microparticles, the adhesive strength between the base film and the transfer control layer, and between the ink layer and the transfer control layer, is insufficient, which tends to cause problems with foil falling off of the ink layer and the transfer control layer, and to cause the surface peeling of the printed image when printing is performed in a high-temperature environment to become very poor. For this reason, it is preferable to add a thermoplastic resin having adhesive properties to the transfer control layer of the present invention in addition to the aliphatic hydrocarbon synthetic wax microparticles.

As the thermoplastic resin having adhesiveness to be added to the transfer control layer of the present invention, it is preferable to use a thermoplastic resin having suitable adhesiveness, which does not adversely affect the transferability of the print, which does not adversely affect the environmental preservation performance in a high-temperature environment, and which has properties such that the printed image does not undergo surface peeling when printed in a high-temperature environment. As a result of the inventor's investigation into such a thermoplastic resin, it was found that it is preferable to use a carboxylic acid-modified polyolefin.

The carboxylic acid-modified polyolefin added to the transfer control layer of the present invention refers to a polyolefin modified with at least one or more kinds of various unsaturated carboxylic acids or their anhydrides. The polymerization method of the carboxylic acid-modified polyolefin is not particularly limited, and it may be a block copolymer or random copolymer obtained by copolymerizing a polyolefin (olefin polymer or olefin copolymer) with an unsaturated carboxylic acid or its anhydride as a copolymerization component, or a graft copolymer obtained by grafting an unsaturated carboxylic acid or its anhydride to a polyolefin.

The polyolefin, which is the main component of the carboxylic acid-modified polyolefin, refers to various olefin polymers and various olefin copolymers. Examples of polyolefins that can be used as raw materials for the carboxylic acid-modified polyolefin to be added to the transfer control layer of the present invention include polyethylene, polypropylene, ethylene-propylene copolymers, and copolymers of ethylene or propylene and various α-olefins (e.g., 1-butene, isobutene, 4-methyl-1-pentene, 1-hexene, 1-octene), and these can be suitably selected and used depending on the required quality.

Examples of the unsaturated carboxylic acid and its anhydride constituting the carboxylic acid-modified polyolefin added to the transfer control layer of the present invention include fumaric acid, maleic acid, itaconic acid, citraconic acid, anicotonic acid, acrylic acid, methacrylic acid, and anhydrides of the unsaturated carboxylic acids, which can be suitably used according to the required quality, but it is more preferable to use fumaric acid, maleic acid, maleic anhydride, itaconic acid, and itaconic anhydride. By modifying the polyolefin with a carboxylic acid, it is possible to impart adhesiveness to the polyolefin.

Regarding the carboxylic acid-modified polyolefin added to the transfer control layer of the present invention, the proportion of the unsaturated carboxylic acid and its anhydride constituting the carboxylic acid-modified polyolefin is not particularly limited, but is preferably in the range of 0.1 mass % or more and 20.0 mass % or less of the total carboxylic acid-modified polyolefin, more preferably in the range of 0.1 mass % or more and 10.0 mass % or less, and most preferably in the range of 0.1 mass % or more and 5.0 mass % or less.

The carboxylic acid-modified polyolefin may be further modified with a derivative of an unsaturated carboxylic acid as necessary. Examples of the unsaturated carboxylic acid derivative include various unsaturated carboxylic acid esters and various unsaturated carboxylic acid amides, and it is more preferable to use an unsaturated carboxylic acid ester. Examples of the unsaturated carboxylic acid ester include various fumaric acid esters, various maleic acid esters, various itaconic acid esters, various citraconic acid esters, various anicotonic acid esters, various acrylic acid esters, and various methacrylic acid esters, and these can be suitably used according to the required quality, but it is more preferable to use various acrylic acid esters and various methacrylic acid esters. By further modifying the carboxylic acid-modified polyolefin with an unsaturated carboxylic acid derivative, it is expected that the effect of improving compatibility with other resins and the like and further imparting adhesiveness can be obtained.

Regarding the carboxylic acid-modified polyolefin added to the transfer control layer of the present invention, the proportion of the unsaturated carboxylic acid derivative constituting the carboxylic acid-modified polyolefin is not particularly limited, but is preferably in the range of 0.1 mass % or more and 30.0 mass % or less of the total carboxylic acid-modified polyolefin, and more preferably in the range of 0.1 mass % or more and 10.0 mass % or less.

The present inventors have studied the carboxylic acid-modified polyolefin to be added to the transfer control layer of the present invention, and have found that it is more preferable to use carboxylic acid-modified polyethylene or carboxylic acid-modified polypropylene, and most preferable to use carboxylic acid-modified polypropylene. In particular, the present inventors have found that adding carboxylic acid-modified polypropylene to the transfer control layer makes it possible to more effectively suppress the occurrence of planar peeling in a printed image when printing is performed in a high-temperature environment. The polyolefin component in the carboxylic acid-modified polyethylene of the present invention includes polyethylene or ethylene-α-olefin copolymers containing up to 10 mol % of α-olefin monomers. Similarly, the polyolefin component in the carboxylic acid-modified polypropylene of the present invention includes polypropylene or propylene-α-olefin copolymers containing up to 10 mol % of α-olefin monomers.

The present inventors have investigated the thermal properties of the carboxylic acid-modified polyolefin added to the transfer control layer, and found that the melting peak temperature of the carboxylic acid-modified polyolefin measured by differential scanning calorimetry is preferably 100° C. or higher, more preferably 110° C. or higher. If the melting peak temperature of the carboxylic acid-modified polyolefin is 100° C. or higher, the carboxylic acid-modified polyolefin hardly softens in a high-temperature environment of 50° C., so that the transfer control layer itself does not soften or deform. As a result, the environmental preservation performance in a high-temperature environment of 50° C. is improved, and at the same time, the effect of suppressing the occurrence of surface peeling in the printed image when printing is performed in a high-temperature environment of 40° C. is greatly improved. Conversely, if the peak temperature of the carboxylic acid-modified polyolefin is below 100° C., the environmental preservation performance in a high-temperature environment of 50° C. gradually deteriorates, and the surface peeling of the printed image when printing is performed in a high-temperature environment tends to deteriorate rapidly.

The upper limit of the melting peak temperature of the carboxylic acid-modified polyolefin is not particularly limited, but from the viewpoint of printing sensitivity, it is preferably 165° C. or less, and more preferably 150° C. or less. When the upper limit of the melting peak temperature of the carboxylic acid-modified polyolefin is within the above range, the printing sensitivity and environmental preservation performance in a high-temperature environment are good, and it is possible to effectively suppress the occurrence of planar peeling in a printed image when printing is performed in a high-temperature environment.

The inventors further investigated the thermal properties of the aliphatic hydrocarbon synthetic wax microparticles and carboxylic acid-modified polyolefin added to the transfer control layer and found that a higher melting peak temperature of the carboxylic acid-modified polyolefin than the melting peak temperature of the aliphatic hydrocarbon synthetic wax microparticles can more effectively suppress the occurrence of planar peeling in printed images when printing is performed in a high-temperature environment.

The amount of the carboxylic acid-modified polyolefin added to the transfer control layer is preferably at least 5% by mass of the entire transfer control layer, more preferably 15% by mass or more. Conversely, the upper limit of the amount added is preferably 50% by mass or less of the entire transfer control layer, more preferably 35% by mass or less. If the amount of the carboxylic acid-modified polyolefin added is within the above range, not only is a sufficient effect of suppressing the occurrence of surface peeling in the printed image when printing is performed in a high-temperature environment exhibited, but the transferability of the print is good and foil-falling of the ink layer and the transfer control layer is also suppressed well. If the amount of the carboxylic acid-modified polyolefin added is below the lower limit of the above range, there is a tendency that surface peeling is easily caused in the printed image when printing is performed in a high-temperature environment, or foil-falling of the ink layer and the transfer control layer is easily caused, and conversely, if the amount of the carboxylic acid-modified polyolefin added exceeds the upper limit of the above range, there is a tendency that the environmental preservation performance and the transferability of the print in a high-temperature environment gradually deteriorate.

In addition to the above-mentioned aliphatic hydrocarbon synthetic wax microparticles and carboxylic acid-modified polyolefins, various additives such as various known organic and inorganic fillers, surfactants, viscosity modifiers, and antistatic agents may be added to the transfer control layer of the present invention in small amounts as needed, as long as they do not impair the required quality of the transfer control layer.

The coating amount of the transfer control layer of the present invention after drying is not particularly limited and may be appropriately selected from the range of 0.1 g/m ² or more and 1.0 g/m ² or less, but it is more preferable to select from the range of 0.2 g/m ² or more and 0.8 g/m ² or less in consideration of printing sensitivity and transferability. If the coating amount of the transfer control layer after drying is less than 0.1 g/m ² , peeling cannot be performed properly at the interface between the transfer control layer and the base film, and transfer failure tends to occur, and conversely, if the coating amount of the transfer control layer after drying exceeds 1.0 g/m ² , foil peeling of the ink layer or the transfer control layer tends to occur easily, and printing sensitivity tends to deteriorate.

<Ink Layer>
The thermal melt transfer ink ribbon of the present invention has an ink layer containing at least a coloring component such as various known organic or inorganic pigments such as carbon black, and a binder component such as a thermoplastic resin or various known waxes, as the outermost layer on the transfer control layer provided on the base film. The amount of colorant added is not particularly limited, but it is preferable to use an appropriate amount from 10% by mass to 50% by mass, more preferably 15% by mass to 30% by mass, of the entire ink layer depending on the usage situation. If the amount added is less than 10% by mass, the print density of the printed matter is insufficient, and if it exceeds 50% by mass, it tends to have a negative effect on the transferability of the print.

As a result of the inventors' investigation into the binder components to be added to the ink layer of the present invention, it has been found that from the viewpoint of improving printing sensitivity, transferability of the print, and adhesion of the printed image to a transfer medium such as a label, it is preferable to add an adhesive resin with a relatively low melting point, and further, taking into consideration compatibility with the transfer control layer described above, it is preferable to use an ethylene-based copolymer resin.

The ethylene-based copolymer resin added to the ink layer of the present invention is a copolymer having an ethylene component as a main component, and examples of the ethylene-based copolymer that are particularly suitable for use include ethylene-(meth)acrylate copolymer resins such as ethylene-methyl(meth)acrylate copolymer, ethylene-ethyl(meth)acrylate copolymer, ethylene-propyl(meth)acrylate copolymer, and ethylene-butyl(meth)acrylate copolymer, ethylene-(meth)acrylamide copolymer resin, and ethylene-vinyl acetate copolymer resin. Furthermore, it is also possible to use the above-mentioned various copolymer resins modified with various carboxylic acids, maleic anhydride, etc. Furthermore, as a result of further investigations, the inventors have found that it is most preferable to use an ethylene-vinyl acetate copolymer resin as the ethylene-based copolymer added to the ink layer. The above-mentioned "(meth)acrylate" is a technical term that includes "acrylate" and "methacrylate".

The ethylene-based copolymer resin added to the ink layer of the present invention is composed of ethylene as the main component and other components copolymerized with ethylene, such as vinyl acetate and various (meth)acrylates, and in the ethylene-based copolymer resin used in the present invention, the ratio of the other components is preferably at least 5% by mass or more of the entire ethylene-based copolymer resin, more preferably 10% by mass or more, and most preferably 20% by mass or more. Conversely, the ratio of other components copolymerized with ethylene in the entire ethylene-based copolymer resin is preferably at least 40% by mass or less of the entire ethylene-based copolymer resin, more preferably 30% by mass or less. If the ratio of other components copolymerized with ethylene is within the above range, the printing sensitivity, the transferability of the print, and the adhesion of the printed image to the transfer medium are improved, and further, the printed image tends to be less likely to peel off when printed under a high temperature environment.

As a result of the present inventors' investigation into the thermal properties of the ethylene-based copolymer resin added to the ink layer of the present invention, the lower limit of the melting peak temperature of the ethylene-based copolymer resin measured by differential scanning calorimetry is preferably 60° C. or higher, more preferably 70° C. or higher. Conversely, the upper limit of the melting peak temperature of the ethylene-based copolymer resin is preferably 110° C. or lower, more preferably 90° C. or lower. If the melting peak temperature of the ethylene-based copolymer resin is within the above range, not only is the printing sensitivity and print transferability good, and the adhesion of the printed image to the print-receiving medium good, but the environmental preservation performance in a high-temperature environment of 50° C. is not significantly deteriorated, and the surface peeling of the printed image when printing is performed in a high-temperature environment of 40° C. is not significantly deteriorated. On the other hand, if the melting peak temperature of the ethylene-based copolymer resin is below the lower limit of the above range, the environmental preservation performance in a high-temperature environment and the surface peeling of the printed image when printing is performed in a high-temperature environment rapidly deteriorate, and if the melting peak temperature of the ethylene-based copolymer resin is above the upper limit of the above range, the printing sensitivity and the transferability of the print rapidly deteriorate, and as a result, the adhesion of the printed image to the print-receiving medium also deteriorates.

The lower limit of the amount of the ethylene-based copolymer resin added to the ink layer is preferably 20% by mass or more, more preferably 25% by mass or more, of the entire ink layer. Conversely, the upper limit of the amount of the ethylene-based copolymer resin added to the ink layer is preferably 50% by mass or less, more preferably 40% by mass or less, of the entire ink layer. If the amount of the ethylene-based copolymer resin added to the ink layer is within the above range, not only is the printing sensitivity and the transferability of the print good, and the adhesion of the printed image to the print-receiving medium good, but the environmental preservation performance in a high-temperature environment of 50° C. is not significantly deteriorated, and the surface peeling of the printed image when printed in a high-temperature environment of 40° C. is not significantly deteriorated. On the other hand, if the amount of the ethylene-based copolymer resin added to the ink layer is below the lower limit of the above range, the printing sensitivity and the transferability of the print tend to deteriorate, and as a result, the adhesion of the printed image to the print-receiving medium also tends to deteriorate. Also, if the amount of the ethylene-based copolymer resin added to the ink layer exceeds the upper limit of the above range, the environmental preservation performance in a high-temperature environment and the surface peeling of the printed image when printing in a high-temperature environment tend to deteriorate.

By adding the above-mentioned ethylene-based copolymer resin as the binder component of the ink layer of the present invention, it is possible to improve the printing sensitivity and the transferability of the print, but on the other hand, the addition of an ethylene-based copolymer resin does not show a good tendency with respect to environmental preservation performance in a high-temperature environment or surface peeling of the printed image when printing is performed in a high-temperature environment, so that if only an ethylene-based copolymer resin is used as the binder component of the ink layer, the environmental preservation performance in a high-temperature environment of 50° C. is not satisfactory, and when printing is performed in a high-temperature environment of 40° C., severe surface peeling occurs in the printed image. In view of this, the present inventors have investigated other raw materials as the binder component, and as a result, it has been found that, in addition to the ethylene-based copolymer resin as the binder component of the ink layer, it is preferable to add a heat-melting substance such as wax in order to improve the printing sensitivity, suppress the occurrence of surface peeling of the printed image when printing is performed in a high-temperature environment, and improve the environmental preservation performance in a high-temperature environment, and in particular, it is more preferable to add an aliphatic hydrocarbon synthetic wax having a melting peak temperature of 100° C. or more. As a result of further investigations, the present inventors have found that by adding fine particles of an aliphatic hydrocarbon synthetic wax having a peak melting temperature of 100°C or higher as a binder component of the ink layer, it is possible to improve the environmental preservation performance in high-temperature environments and to effectively suppress the occurrence of planar peeling in printed images when printing is performed in high-temperature environments.

The aliphatic hydrocarbon synthetic wax, which is the raw material of the aliphatic hydrocarbon synthetic wax fine particles added as a binder component of the ink layer of the present invention, can be preferably the same as the aliphatic hydrocarbon synthetic wax added to the transfer control layer described above. Examples of such aliphatic hydrocarbon synthetic wax include polyethylene wax, polypropylene wax, olefin copolymers having a number average molecular weight of 10,000 or less (e.g., ethylene-polypropylene copolymer, ethylene-α-olefin copolymer, propylene-α-olefin copolymer), and Fischer-Tropsch wax. From the viewpoint of excellent transferability of print, environmental preservation performance in a high-temperature environment, and the effect of suppressing the occurrence of surface peeling in a printed image when printing is performed in a high-temperature environment, it is more preferable to add at least one of Fischer-Tropsch wax and polyethylene wax, and it is most preferable to add polyethylene wax.

The aliphatic hydrocarbon synthetic wax added as a binder component to the ink layer of the present invention is preferably dispersed in the ink layer, since it can improve the sheet-cutting property of the ink layer itself and more effectively suppress the occurrence of surface peeling in the printed image, and the aliphatic hydrocarbon synthetic wax added to the ink layer of the present invention is used in a state processed into fine particles. By adding the aliphatic hydrocarbon synthetic wax dispersed in the ink layer in the form of fine particles, it is possible to easily control the releasability between other layers during printing and further improve the sheet-cutting property of the ink layer by providing a structural difference, adhesive strength difference, or melting peak temperature difference between the fine particle portion and the other portion, and as a result, it is possible to more effectively suppress the occurrence of surface peeling in the printed image.

The average particle diameter of the aliphatic hydrocarbon synthetic wax fine particles added as a binder component of the ink layer of the present invention is not particularly limited, but is preferably in the range of 1.0 μm to 40.0 μm, and more preferably in the range of 2.0 μm to 30.0 μm. If the average particle diameter of the aliphatic hydrocarbon synthetic wax fine particles is within the above range, there is no adverse effect on the environmental preservation performance in a high temperature environment, the suppression of surface peeling of the printed image when printing is performed in a high temperature environment, the foil sharpness of the ink layer, the printing sensitivity, the transferability of the print, etc. In particular, when the average particle diameter of the aliphatic hydrocarbon synthetic wax fine particles is larger than the ink film thickness calculated from the adhesion amount after drying of the ink layer and the density of each raw material, the aliphatic hydrocarbon synthetic wax fine particles protrude from the ink layer surface, and thus the environmental preservation performance (particularly the blocking resistance performance) in a high temperature environment is significantly improved. The average particle diameter of the aliphatic hydrocarbon synthetic wax microparticles is calculated by photographing the ink layer at 10,000 times magnification using an electron microscope, randomly selecting 20 aliphatic hydrocarbon synthetic wax microparticles from the photographed image, measuring the maximum diameter of each microparticle, and averaging the measured diameters.

As a result of the inventors' investigation into the thermal properties of the aliphatic hydrocarbon synthetic wax microparticles added as a binder component in the ink layer of the present invention, it has been found that the lower limit of the melting peak temperature of the aliphatic hydrocarbon synthetic wax microparticles measured by differential scanning calorimetry is preferably 100° C. or higher. Conversely, the upper limit of the melting peak temperature of the aliphatic hydrocarbon synthetic wax microparticles is preferably 140° C. or lower, and more preferably 130° C. or lower. When the melting peak temperature of the aliphatic hydrocarbon synthetic wax microparticles is within the above range, it is possible to improve the environmental preservation performance in a high-temperature environment and the effect of suppressing planar peeling of a printed image when printing is performed in a high-temperature environment. On the other hand, if the melting peak temperature of the aliphatic hydrocarbon synthetic wax microparticles is below the lower limit of the above range, the environmental preservation performance in a high-temperature environment tends to deteriorate, and the surface peeling of the printed image when printing in a high-temperature environment tends to deteriorate. Conversely, if the melting peak temperature of the aliphatic hydrocarbon synthetic wax microparticles is above the upper limit of the above range, the printing sensitivity, the transferability of the print, and the adhesion of the printed image to the print medium tend to deteriorate.

The amount of the aliphatic hydrocarbon synthetic wax microparticles added as a binder component of the ink layer of the present invention is preferably at least 5% by mass or more of the entire ink layer, more preferably 10% by mass or more, and conversely, the upper limit of the amount added is preferably 30% by mass or less of the entire ink layer, more preferably 25% by mass or less. If the amount of the aliphatic hydrocarbon synthetic wax microparticles added is within the above range, it is possible to improve the environmental preservation performance in a high-temperature environment and effectively suppress the surface peeling of the printed image when printing is performed in a high-temperature environment. On the other hand, if the amount of the aliphatic hydrocarbon synthetic wax microparticles added is below the lower limit of the range, the environmental preservation performance in a high-temperature environment and the surface peeling of the printed image when printing is performed in a high-temperature environment tend to deteriorate, and conversely, if the amount exceeds the upper limit of the range, the printing sensitivity, the transferability of the print, and the adhesion of the printed image to the print-receiving medium tend to deteriorate.

As the binder component of the ink layer of the present invention, in addition to the above-mentioned ethylene-based copolymer resin and aliphatic hydrocarbon synthetic wax particles, it is preferable to add a resin that has the effect of improving the transferability of the print and the adhesion of the printed image to the print medium, and further improving the foil-cutting properties of the ink layer. Examples of resins having the above-mentioned effects include various known tackifying resins, such as wood rosin, rosin ester, hydrogenated rosin, disproportionated rosin, polymerized rosin, modified rosin, pinene resin, dipentene resin, hydrogenated terpene resin, aromatic modified terpene resin, aromatic modified hydrogenated terpene resin, terpene phenol resin, hydrogenated terpene phenol resin, C5-based hydrocarbon resin, C9-based hydrocarbon resin, C5-based/C9-based hydrocarbon copolymer resin, hydrogenated C5-based hydrocarbon resin, hydrogenated C9-based hydrocarbon resin, hydrogenated C5-based/C9-based hydrocarbon copolymer resin, chroman resin, chroman-indene resin, various phenol-based tackifying resins, various styrene-based tackifying resins, ketone resin, and the like. These tackifying resins can be used alone or in combination as appropriate.

Among the tackifier resins, styrene-based tackifier resins can be particularly preferably used as the tackifier resin of the binder component of the ink layer of the present invention. Examples of styrene-based tackifier resins include resins made of styrene-based monomer polymers, α-methylstyrene polymers, α-methylstyrene-styrene copolymers, copolymers of styrene-based monomers and aliphatic hydrocarbons, copolymers of styrene-based monomers and (meth)acrylic acid derivatives, copolymers of styrene-based monomers and aromatic hydrocarbons, and ternary copolymers of styrene-based monomers, α-methylstyrene and aliphatic hydrocarbons. It has been found that by using a styrene-based tackifier resin as the tackifier resin of the binder component of the ink layer, it is possible to effectively suppress surface peeling of the printed image when printing is performed in a high-temperature environment.

The tackifier resin added as a binder component of the ink layer of the present invention is preferably a resin having a relatively low molecular weight of several hundred to several thousand or less, having many functional groups in its structure, and having compatibility with other resins and a function of improving the tack and adhesiveness of the layer to which it is added. By adding a tackifier resin to the ink layer, it is expected to improve pigment dispersibility, printing sensitivity, transferability and adhesiveness of the print to the transfer medium, and foil cutting properties of the ink layer. As the tackifier resin used in the present invention, it is preferable to use a tackifier resin having a relatively high softening point or high glass transition point from the viewpoint of improving environmental preservation performance in a high temperature environment and suppressing surface peeling of the printed image when printing is performed in a high temperature environment.

As a result of the inventor's investigation into the thermal properties of the tackifier resin added as a binder component of the ink layer of the present invention, the glass transition point of the tackifier resin measured by differential scanning calorimetry is preferably in the range of 50° C. to 110° C., more preferably in the range of 60° C. to 90° C. The softening point of the tackifier resin (softening point by ring and ball method JIS K5601-2-2 (1999)) is preferably in the range of 110° C. to 170° C., more preferably in the range of 120° C. to 160° C. If the glass transition point or softening point of the tackifier resin is in the above range, it is possible to prevent adverse effects on printing sensitivity and environmental preservation performance in a high-temperature environment, and further to suppress the occurrence of planar peeling during printing in a high-temperature environment.

The amount of the tackifier resin added as a binder component of the ink layer of the present invention is preferably in the range of 5% by mass to 30% by mass, more preferably in the range of 5% by mass to 25% by mass. If the amount of the tackifier resin added is within the above range, the transferability and adhesion to the print-receiving medium are good, there is little adverse effect on the environmental preservation performance in a high-temperature environment, and further, it is possible to effectively suppress surface peeling of the print when printing is performed in a high-temperature environment.

In addition to the above-mentioned coloring components, and the binder components such as the ethylene-based copolymer resin, aliphatic hydrocarbon synthetic wax fine particles, and tackifying resin, various additives such as various known organic and inorganic fillers, surfactants, viscosity modifiers, and antistatic agents may be added to the ink layer of the present invention in small amounts as needed to the extent that the required quality of the ink layer is not impaired.

The coating amount of the ink layer after drying of the present invention is not particularly limited and may be appropriately selected from the range of 0.5 g/ ^m2 or more and 2.0 g/ ^m2 or less depending on the required quality, but it is more preferable to appropriately select from the range of 0.7 g/m2 or ^more and 1.5 g/ ^m2 or less from the viewpoints of cost and performance stability. If the coating amount of the ink layer after drying is less than 0.5 g/ ^m2 , sufficient print density and abrasion resistance tend not to be obtained, and conversely, if the coating amount exceeds 2.0 g/ ^m2 , the printing sensitivity tends to deteriorate, and the surface peeling of the printed image tends to deteriorate due to the deterioration of the foil cutting property of the ink layer.

EXAMPLES Next, the present invention will be specifically described with reference to examples and comparative examples, but the present invention is not limited to the following examples.

<Method of forming the base film and the heat-resistant slip layer>
The heat-resistant slipping layer coating material shown below was applied to one side of a 4.5 μm-thick polyethylene terephthalate film (PET film) using a gravure coater, and the solvent components were evaporated and dried using a hot air dryer to form a heat-resistant slipping layer so that the adhesion amount after drying was 0.2 g/ ^m2 .
(Paint formulation for heat-resistant slipping layer)
Raw material component mass%
Silicone-modified polyester polyurethane resin dissolved in methyl ethyl ketone/toluene = 1/1 solvent (solid content 15% by mass) 25.0
Methyl ethyl ketone 60.0
Toluene 15.0
The heat-resistant slipping layer coating material is prepared by weighing out a mixed solvent of methyl ethyl ketone and toluene and a solution in which a silicone-modified polyester polyurethane resin is dissolved in a solvent with a mass ratio of 1:1 between methyl ethyl ketone and toluene to a solid content of 15 mass%, respectively, according to the above-mentioned formulation, and putting them into a container and stirring and mixing with a dissolver or the like. The above-mentioned method for preparing the heat-resistant slipping layer coating material and the method for forming the heat-resistant slipping layer are only examples and are not limited thereto, and various known methods can be used. Note that the above-mentioned heat-resistant substrate film and heat-resistant slipping layer were used in all of the examples and comparative examples of the present invention.

<Method of forming transfer control layer>
Details of the transfer control layer and the method of forming it in the examples and comparative examples of the present invention are shown below.

Table 1 shows details of each heat-fusible substance used in the transfer control layer of the examples and comparative examples of the present invention, and Table 2 shows details of each thermoplastic resin.

(Method of preparing paint for transfer control layer)
Using emulsion raw materials obtained by emulsifying each of the heat-fusible substances listed in Table 1 in water, dispersion raw materials obtained by dispersing each of the thermoplastic resins listed in Table 2 in water, and isopropanol, paints 1 to 13 for transfer control layers shown in Tables 3 and 4 were prepared. The emulsion raw materials and dispersion raw materials may be appropriately selected from commercially available raw materials containing the compositions shown in Tables 1 and 2 as solids, or may be prepared by emulsifying or dispersing the compositions shown in Tables 1 and 2 in water. A specific method for preparing the paint for transfer control layers is to measure and charge each raw material into a container in the amounts shown in Tables 3 and 4, and thoroughly stir and mix with a stirrer to prepare the paint.

※上記の表３及び表４中の熱融解性物質の平均粒子径は、転写制御層を形成した後に、電子顕微鏡で拡大撮影した写真を元に測定及び計算した値である。

*The average particle diameters of the heat-fusible substances in Tables 3 and 4 above are values measured and calculated based on enlarged photographs taken with an electron microscope after the transfer control layer was formed.

(Method of forming transfer control layer)
Next, the method of forming the transfer control layer used in the examples and comparative examples will be specifically described. After applying the paint for the transfer control layer shown in Tables 3 and 4 to the other side of the surface of the PET film on which the heat-resistant slipping layer was provided by a gravure coater, the dispersion medium components such as water and isopropanol contained in the paint were evaporated and dried by a hot air dryer, and each transfer control layer was formed so that the adhesion amount after drying was 0.5 g/ ^m2 . Note that the above-mentioned method of preparing the paint for the transfer control layer and the method of forming the transfer control layer are only examples and are not limited thereto, and various known methods can be used. In addition, details of the solid mass ratio of each raw material in the transfer control layer formed in each example and comparative example (mass ratio of the components of the transfer control layer) are separately described in Tables 9 to 11 below.

<Method of forming ink layer>
Details of the ink layers and the methods of forming them in the examples and comparative examples of the present invention are given below.

Table 5 shows details of each adhesive resin used in the ink layer of the examples and comparative examples of the present invention, Table 6 shows details of each heat-fusible substance, and Table 7 shows details of each tackifier resin.

(Method of preparing paint for ink layer)
First, toluene and the heat-melting substance shown in Table 6 are weighed and charged into a sealable container that can be stirred and heated so that the mass ratio is "toluene: heat-melting substance = 9: 1", the container is sealed and then heated while stirring to completely dissolve the heat-melting substance in toluene, and the solution is gradually cooled while stirring to precipitate fine particles of the heat-melting substance in toluene, thereby preparing a toluene dispersion of the heat-melting substance with a solid content of 10 mass %. Furthermore, toluene, the adhesive resin shown in Table 5, and the tackifier resin shown in Table 7 are weighed and charged into another sealable container that can be stirred and heated so that the mass ratio is shown in Table 8, and the container is sealed and then heated while stirring to prepare a solution in which the adhesive resin and tackifier resin are completely dissolved in toluene. After cooling the toluene solution of the adhesive resin and tackifier resin to room temperature, the toluene dispersion of the heat-fusible substance prepared above is weighed out and mixed in the amount shown in Table 8 to obtain the mass ratio shown in Table 8, and then the other raw materials shown in Table 8 are weighed out and mixed in the amount shown in Table 8 to obtain the mass ratio shown in Table 8 to obtain a preparation liquid before dispersion using a disperser, and finally the preparation liquid is dispersed using a bead mill to the required paint state as appropriate, thereby completing the preparation of the paint for each ink layer shown in Table 8.

※上記の表８中の熱融解性物質の平均粒子径は、インク層を形成した後に、電子顕微鏡で拡大撮影した写真を元に測定及び計算した値である。

*The average particle size of the heat-fusible substance in Table 8 above is a value measured and calculated based on a magnified photograph taken with an electron microscope after the ink layer was formed.

(Method of forming ink layer)
Next, the method of forming the ink layer used in the examples and comparative examples will be specifically described. After applying each of the ink layer paints shown in Table 8 to the upper layer of the transfer control layer provided on the above-mentioned PET film using a gravure coater, the dispersion medium and solvent components such as toluene, methyl ethyl ketone, and isopropanol contained in the paint were evaporated and dried using a hot air dryer, and each ink layer was formed so that the adhesion amount after drying was 1.0 g/ ^m2 . Note that the above-mentioned method of preparing the ink layer paint and the method of forming the ink layer are only examples and are not limited thereto, and various known methods can be used. In addition, details of the solid mass ratios of each raw material in the ink layers formed in each of the examples and comparative examples (mass ratios of the components of the ink layer) are separately described in Tables 9 to 11 below.

<<Evaluation method>>
The printing test conditions and various evaluation methods using the thermal melt transfer ink ribbons of the examples and comparative examples having the configurations shown in Tables 9 to 11 are shown below.

<Printing test conditions>
Using the thermal melt transfer ink ribbons of the Examples and Comparative Examples, various printing tests were carried out under the following conditions.
Printer: CL4NX-J (manufactured by Sato Corporation)
Print resolution: 305 dpi
Printing speed: 5inch/sec
Print density: 5/10, 9/10
Printing media: PET label

<(Evaluation 1) Evaluation of printing sensitivity of test samples not stored in an environment>
Using the thermal melt transfer ink ribbons of the Examples and Comparative Examples that had not been subjected to an environmental storage test, printing was performed under the above-mentioned printing test conditions in an environment with an air temperature of 25°C, and the state of each printed image was visually inspected to evaluate the printing sensitivity under the conditions shown below.
A: No blurring of the print occurs.
B: Slight smearing of the print occurs in some areas.
C . . . Print smearing was clearly observed over almost the entire surface.
D: The print is very smudged and almost no print has been transferred.

<(Evaluation 2) Evaluation of print quality of test samples not stored in an environment>
Using the thermal melt transfer ink ribbons of the Examples and Comparative Examples that had not been subjected to an environmental storage test, printing was performed under the above-mentioned printing test conditions in an environment with an air temperature of 25°C, and the condition of each printed image was visually inspected to evaluate the print quality under the conditions shown below.
A: No chipping or surface peeling occurred in the printed image.
B: Slight chipping and/or surface peeling occurred in part of the printed image.
C: Print chipping and/or surface peeling is clearly observed in part of the printed image.
D: Severe print chipping and/or surface peeling occurs over almost the entire surface of the printed image.

<(Evaluation 3) Evaluation of printing sensitivity of environmentally preserved test samples>
After an environmental storage test was conducted in which the thermal melt transfer ink ribbons of the Examples and Comparative Examples were left to stand for 96 hours in an atmosphere in a thermostatic chamber set at a temperature of 50°C and a humidity of 80% RH, the thermal melt transfer ink ribbons were left to stand for 24 hours in a room temperature environment at a temperature of 25°C, and printing was performed under the above printing test conditions in an environment at a temperature of 25°C. The state of each printed image was visually inspected to evaluate the printing sensitivity under the conditions shown below.
A: No blurring of the print occurs.
B: Slight smearing of the print occurs in some areas.
C . . . Print smearing was clearly observed over almost the entire surface.
D: The print is very smudged and almost no print has been transferred.

<(Evaluation 4) Evaluation of print quality of environmentally preserved test samples>
After an environmental preservation test was conducted in which the thermal melt transfer ink ribbons of the Examples and Comparative Examples were left to stand for 96 hours in an atmosphere in a thermostatic chamber set at a temperature of 50°C and a humidity of 80% RH, the thermal melt transfer ink ribbons were left to stand for 24 hours in a room temperature environment at a temperature of 25°C, and printing was performed under the above printing test conditions in an environment at a temperature of 25°C. The state of each printed image was visually inspected to evaluate the print quality under the conditions shown below.
A: No chipping or surface peeling occurred in the printed image.
B: Slight chipping and/or surface peeling occurred in part of the printed image.
C: Print chipping and/or surface peeling is clearly observed in part of the printed image.
D: Severe print chipping and/or surface peeling occurs over almost the entire surface of the printed image.

<(Evaluation 5) Evaluation of changes in print sensitivity and print quality due to environmental preservation test (environmental preservation performance)>
The state of each printed image in the above evaluations (Evaluation 1) to (Evaluation 4) was compared visually and evaluated under the conditions shown below.
A: There is absolutely no change in print sensitivity and print quality after the environmental storage test.
B: After the environmental storage test, at least one of the printing sensitivity, printing chipping, and surface peeling is slightly worse than before the environmental storage test.
C . . . After the environmental storage test, at least one of the printing sensitivity, printing chipping, and surface peeling is clearly deteriorated compared to before the environmental storage test.
D: After the environmental storage test, at least one of the printing sensitivity, printing chipping, and surface peeling is significantly worse than before the environmental storage test.

<(Evaluation 6) Evaluation of Blocking Resistance (Environmental Preservation Performance)>
To evaluate blocking resistance, a raw thermal melt transfer ink ribbon was slit to a specified size and wound around a plastic core to create a rolled ribbon sample (width 50 mm, length 100 m, ink surface inward). The ribbon sample was then left to stand for 96 hours in an atmosphere in a thermostatic chamber set at a temperature of 50°C and a humidity of 80% RH, after which it was cooled for 24 hours in a room temperature environment at a temperature of 25°C. The ribbon sample was then unwound and the state of blocking was visually observed and evaluated under the conditions shown below.
A: No blocking was observed.
B: Slight blocking was observed near the plastic core of the ribbon sample.
C: Partial blocking was observed between the middle of winding the ribbon sample and near the plastic core.
D: Blocking was observed over the entire surface of the ribbon sample.

<(Evaluation 7) Evaluation of surface peeling of printed images when printed in a high temperature environment>
The printer used in the printing test, the PET label as the print medium, and the hot melt transfer ink ribbon used for printing were left to stand for one hour in the atmosphere of a thermostatic chamber set at a temperature of 40°C, and then printing was continued in the same thermostatic chamber under the above printing conditions at a print density of 5/10. Each printed image was visually confirmed and evaluated under the conditions shown below.
A: No surface peeling occurred in the printed image.
B: Slight surface peeling occurred in part of the printed image.
C: Clear surface peeling was observed in part of the printed image.
D: Severe surface peeling occurred over almost the entire surface of the printed image.

The thermal melt transfer ink ribbons of each Example and Comparative Example were prepared using the method described above, and the mass ratios of the components of the ink layer and transfer control layer of each Example and Comparative Example, as well as the results of the various evaluations described above, are shown in Tables 9 to 11 below.

From the results of Tables 9 to 11, when a thermal melt transfer ink ribbon is used, as in the thermal melt transfer ink ribbons of Examples 1 to 9, in which the ink layer contains a coloring component and a binder component, the binder component of the ink layer contains an ethylene copolymer resin having a peak melting temperature of 60° C. or more, aliphatic hydrocarbon synthetic wax fine particles having a peak melting temperature of 100° C. or more, and a tackifier resin, and the transfer control layer contains aliphatic hydrocarbon synthetic wax fine particles having a peak melting temperature of 100° C. or more in a range of 50% by mass to 95% by mass of the entire transfer control layer, and a carboxylic acid modified polyolefin having a peak melting temperature of 100° C. or more in a range of 5% by mass to 50% by mass of the entire transfer control layer, almost no blocking phenomenon occurs and almost no deterioration in printing sensitivity or printing quality is observed even when an environmental storage test is performed in a high temperature environment. Furthermore, almost no planar peeling occurs in the printed image when printing is performed in a high temperature environment, and further, the printing sensitivity is good.

On the other hand, focusing on the transfer control layer, when a carboxylic acid-modified polyolefin with a peak melting temperature of less than 100°C was used for the transfer control layer instead of a carboxylic acid-modified polyolefin with a peak melting temperature of 100°C or more, as in Comparative Examples 1 to 3 in Table 9, the surface peeling of the printed image when printing was performed in a high-temperature environment was significantly deteriorated, and when the print density was high (print density 9/10) regardless of whether or not an environmental storage test was performed in a high-temperature environment, surface peeling of the printed image occurred significantly, and further, the print quality (surface peeling) deteriorated before and after the environmental storage test in a high-temperature environment. In addition, as in Comparative Examples 4 to 6 in Table 9, when fine particles of a heat-melting substance having a melting peak temperature of less than 100°C are used in the transfer control layer instead of fine particles of aliphatic hydrocarbon synthetic wax having a melting peak temperature of 100°C or more, various problems occur, such as poor surface peeling of the printed image when printing is performed in a high-temperature environment as in Comparative Example 4, poor print sensitivity before and after an environmental storage test in a high-temperature environment as in Comparative Example 5, and a reverse transfer phenomenon occurring during printing, causing the print not to be transferred to the label in the first place as in Comparative Example 6. In addition, as in Comparative Example 7 in Table 10, if the transfer control layer does not contain any carboxylic acid-modified polyolefin, the printed image is likely to have surface peeling, and in particular, when printing is performed in a high-temperature environment, surface peeling clearly occurs in the printed image. In addition, as in Comparative Example 8, when the transfer control layer contains more than 50 mass% of the carboxylic acid-modified polyolefin in the entire transfer control layer, the transferability of the print is poor, and as a result, the print sensitivity is very poor.

Next, looking at the ink layer, when an ethylene copolymer resin having a melting peak temperature of less than 60° C. is used as the binder component of the ink layer as in Comparative Example 9 in Table 11, the print quality (surface peeling) deteriorates after the environmental storage test in a high-temperature environment, and the printed image clearly peels off when printed in a high-temperature environment. When an ink layer of the type used in the thermal melt transfer ink ribbon of Patent Document 1 is used as the ink layer as in Comparative Example 10 in Table 11, the printed image does not peel off, but the print sensitivity is poor and the print is blurred at a print density of 5/10. When fine particles of a heat-melting substance having a melting peak temperature of less than 100° C. are used in the ink layer instead of fine particles of aliphatic hydrocarbon synthetic wax having a melting peak temperature of 100° C. or more as in Comparative Examples 11 and 12 in Table 11, the printed image clearly peels off when printed in a high-temperature environment, and further, in Comparative Example 11, the print quality (surface peeling) deteriorates after the environmental storage test in a high-temperature environment. Furthermore, when no aliphatic hydrocarbon synthetic wax microparticles having a melting peak temperature of 100° C. or more were added to the binder component of the ink layer, as in Comparative Example 13 in Table 11, the printing sensitivity and printing quality (planar peeling) deteriorated after the environmental storage test in a high-temperature environment, and the blocking phenomenon also occurred clearly. Furthermore, when no tackifier resin was added to the binder component of the ink layer, as in Comparative Example 14 in Table 11, significant planar peeling occurred in the printed image regardless of the printing test conditions.

The thermal transfer ink ribbon of the present invention can be used not only in thermal transfer printers used for general purposes such as printing text information and barcodes on various slips, product tags, and logistics management labels, but can also be used as a thermal transfer ink ribbon for thermal transfer printers that are likely to be used in high-temperature environments.

1; hot melt transfer ink ribbon 2; base film 3; heat resistant slip layer 4; transfer control layer 5; ink layer 6; print medium (label, etc.)
7a: Print image (originally intended print image)
7b: Printed image (part where surface peeling occurred)
8; Thermal head 9; Platen roll

Claims (10)

A thermal melt transfer ink ribbon having a heat-resistant slipping layer on one side of a base film and a transfer control layer and an ink layer laminated in this order on the other side,
The ink layer contains a coloring component and a binder component,
the binder component of the ink layer contains an ethylene copolymer resin having a melting peak temperature of 60° C. or more, aliphatic hydrocarbon synthetic wax fine particles having a melting peak temperature of 100° C. or more, and a tackifier resin;
A thermal melt transfer type ink ribbon, wherein the transfer control layer contains aliphatic hydrocarbon synthetic wax microparticles having a melting peak temperature of 100°C or higher in a range of 50% by mass to 95% by mass of the entire transfer control layer, and contains carboxylic acid modified polyolefins having a melting peak temperature of 100°C or higher in a range of 5% by mass to 50% by mass of the entire transfer control layer. 2. The thermal melt transfer ink ribbon according to claim 1, wherein the ink layer contains fine particles of aliphatic hydrocarbon synthetic wax as a binder component of the ink layer in an amount of 5% by mass to 30% by mass of the entire ink layer. 3. The thermal melt transfer ink ribbon according to claim 1, wherein the ink layer contains an ethylene copolymer resin as a binder component of the ink layer in an amount of 20% by mass to 50% by mass of the entire ink layer. 4. The thermal melt transfer ink ribbon according to claim 1, wherein the average particle size of the fine aliphatic hydrocarbon synthetic wax particles contained in the transfer control layer is in the range of 0.1 μm to 5.0 μm. 5. The thermal melt transfer ink ribbon according to claim 1, wherein the ethylene copolymer resin which is the binder component of the ink layer is an ethylene-vinyl acetate copolymer resin. 6. The thermal melt transfer ink ribbon according to claim 1, wherein the fine particles of aliphatic hydrocarbon synthetic wax which are a binder component of the ink layer are made of at least one of fine Fischer-Tropsch wax particles and fine polyethylene wax particles. 7. The thermal melt transfer ink ribbon according to claim 1, wherein the fine particles of aliphatic hydrocarbon synthetic wax contained in the transfer control layer are made of at least one of fine Fischer-Tropsch wax particles and fine polyethylene wax particles. 8. The thermal melt transfer ink ribbon according to claim 1, wherein the fine particles of aliphatic hydrocarbon synthetic wax contained in the transfer control layer are made of Fischer-Tropsch wax fine particles. 9. The thermal melt transfer ink ribbon according to claim 1, wherein the carboxylic acid-modified polyolefin contained in the transfer control layer is a carboxylic acid-modified polypropylene. 10. The thermal melt transfer ink ribbon according to claim 1, wherein the tackifier resin of the binder component of the ink layer is a styrene-based tackifier resin.

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