WO2017170779A1

WO2017170779A1 - Heat transfer sheet

Info

Publication number: WO2017170779A1
Application number: PCT/JP2017/013084
Authority: WO
Inventors: 和起榎田
Original assignee: 大日本印刷株式会社
Priority date: 2016-03-29
Filing date: 2017-03-29
Publication date: 2017-10-05
Also published as: JPWO2017170779A1

Abstract

Provided is a heat transfer sheet with which it is possible to inhibit the occurrence of print wrinkles even when the energy applied to the heat transfer sheet during printing is maintained at a high level. A heat transfer sheet to which a color material layer 3 containing a color material is provided on one surface of a base material 1, wherein energy is applied to the heat transfer sheet 10 at 0.22 mJ/dot on the other surface side of the base material 1, the color material contained in the color material layer 3 is caused to migrate to a transfer body, after which the heat transfer sheet corresponding to the region to which the energy was applied is cut out, and when a tensile test is performed on the cut-out heat transfer sheet at a tensile rate of 3mm/min, the tensile strength is 2.6 N/cm or greater, the tensile strength being obtained by converting the stress (N) at which the cut-out heat transfer sheet reaches a yield point to per 1-cm width of the cut-out heat transfer sheet .

Description

Thermal transfer sheet

The present invention relates to a thermal transfer sheet.

As a general thermal transfer sheet used in a printer, a thermal transfer sheet (for example, Patent Document 1) in which a color material layer is provided on one surface of a substrate is known. Image formation using this thermal transfer sheet is performed by superimposing the transfer material such as a thermal transfer image receiving sheet and the color material layer of the thermal transfer sheet so that the other surface side of the substrate is a heating device such as a thermal head. , And while being wound while applying a certain tension to the thermal transfer sheet, it is moved by rubbing the back side of the substrate while applying energy according to image information to the heating device.

Recently, the market demand for printers excellent in high-speed printing is increasing. In order to satisfy this requirement, the energy applied from the heating device to the thermal transfer sheet per unit time must be increased, and the energy applied to the thermal transfer sheet at the time of printing is very high. By the way, in order to improve the high-speed printing suitability, when the energy applied to the thermal transfer sheet is increased at the time of printing, the thermal transfer sheet is damaged immediately under the heating device at the time of printing, or the thermal transfer sheet. Elongation occurs, and the thermal transfer sheet is damaged and print wrinkles due to the elongation occur.

Under such circumstances, the color material layer provided on one surface of the base material, the measures for improving the slipperiness of the back layer provided on the other surface of the base material, the heat resistance of the base material and the back layer Various measures have been taken for the purpose of suppressing the occurrence of printing wrinkles, such as measures to improve the image quality. Although these measures can suppress printing wrinkles within a certain range under predetermined printing conditions, they are limited by the materials that make up each layer, such as the base material, color material layer, and back layer. The problem of narrowing the range of material selection is inherent. There is also room for improvement in measures against printing wrinkles when using a printer with excellent high-speed printing suitability.

JP 2012-153020 A

The present invention has been made in view of such circumstances, and provides a thermal transfer sheet capable of suppressing the occurrence of printing wrinkles even when the energy applied to the thermal transfer sheet during printing is increased. The main task is to do.

The present invention for solving the above problems is a thermal transfer sheet in which a color material layer containing a color material is provided on one surface of a base material, and the thermal transfer sheet is the other side of the base material. The energy is applied to the side under the condition of 0.22 mJ / dot to transfer the color material contained in the color material layer onto the transfer target, and then the region of the thermal transfer sheet to which the energy is applied is cut out. When the tensile test was performed on the cut-out thermal transfer sheet at a tensile speed of 3 mm / min., The stress (N) when the cut-out thermal transfer sheet reached the yield point was expressed as the cut-out thermal transfer. The tensile strength converted per 1 cm width of the sheet is 2.6 N / cm or more.

According to the thermal transfer sheet of the present invention, the occurrence of printing wrinkles can be suppressed even when the energy applied to the thermal transfer sheet during printing is increased.

It is a schematic sectional drawing which shows an example of the thermal transfer sheet of this invention. It is a schematic sectional drawing which shows an example of the thermal transfer sheet of this invention. It is a schematic sectional drawing which shows an example of the thermal transfer sheet of this invention.

<< Thermal transfer sheet >>
Hereinafter, a thermal transfer sheet according to an embodiment of the present invention (hereinafter referred to as a thermal transfer sheet according to an embodiment) will be described in detail. 1 to 3 are schematic cross-sectional views showing an example of a thermal transfer sheet of one embodiment. As shown in FIGS. 1 to 3, a thermal transfer sheet 10 according to an embodiment includes a base material 1 and a color material layer 3 positioned on one surface of the base material 1. The base material 1 and the color material layer 3 are essential components in the thermal transfer sheet 10 of one embodiment. In the illustrated form, the back surface layer 5 is located on the other surface of the substrate 1, but the back surface layer 5 is an arbitrary configuration in the thermal transfer sheet of one embodiment.

A thermal transfer sheet as shown in FIGS. 1 to 3 is superposed on a transfer object such as a thermal transfer image receiving sheet (hereinafter referred to as a transfer object), and energy is applied from the back side of the thermal transfer sheet by a heating member such as a thermal head. One of the problems that may occur when a printed material is formed by applying the color material of the color material layer to the transferred material to form a printed material is a printing wrinkle. Printing wrinkles are presumed to be the main cause of damage to the thermal transfer sheet or elongation of the thermal transfer sheet immediately below the heating device such as the thermal head during printing using the thermal transfer sheet. The frequency of occurrence tends to increase as the energy applied to is increased.

Under such circumstances, various attempts to suppress the occurrence of printing wrinkles, for example, an attempt to improve the durability of the base material constituting the thermal transfer sheet and the color material layer provided on one surface of the base material, Attempts have been made to provide a back layer on the other side of the material. However, by taking these countermeasures, even if the generation of printing wrinkles can be suppressed under predetermined printing conditions, the generation of printing wrinkles may occur depending on the conditions of energy applied to the thermal transfer sheet during printing. In many cases, it cannot be sufficiently suppressed, and it has not yet been possible to sufficiently suppress the occurrence of printing wrinkles regardless of the energy conditions applied to the thermal transfer sheet during printing. Specifically, in the current situation, when the energy applied to the thermal transfer sheet is increased during printing, the generation of printing wrinkles has not been sufficiently suppressed.

A thermal transfer sheet 10 according to an embodiment in consideration of such a problem is a thermal transfer sheet in which a color material layer 3 containing a color material is provided on one surface of a substrate 1, and the thermal transfer sheet 10 and a transfer target are transferred. After overlapping the body and applying energy on the other surface side of the substrate 1 under the condition of 0.22 mJ / dot to transfer the color material contained in the color material layer 3 onto the transfer target, A region of the thermal transfer sheet 10 to which the energy is applied (a region to which an energy of 0.22 mJ / dot is applied) is cut out, and a tensile test is performed on the cut-out thermal transfer sheet 10 at a tensile speed of 3 mm / min. The tensile strength obtained by converting the stress (N) when the cut-out thermal transfer sheet 10 reaches the yield point when converted to a width of 1 cm of the cut-out thermal transfer sheet is 2.6 N / cm or more. When is doing.

The thermal transfer sheet 10 according to an embodiment having the above features does not focus on the base material 1 constituting the thermal transfer sheet or each layer constituting the thermal transfer sheet, but the tensile strength of the thermal transfer sheet after printing, specifically Is a result of paying attention to the tensile strength of the thermal transfer sheet after the thermal transfer image is formed using the thermal transfer sheet. According to the thermal transfer sheet 10 of the embodiment having the above characteristics, it is possible to suppress the occurrence of printing wrinkles regardless of the conditions during printing only by satisfying this tensile strength. Specifically, according to the thermal transfer sheet 10 of one embodiment, the occurrence of printing wrinkles can be suppressed even when the energy applied to the thermal transfer sheet is extremely high during printing in order to cope with high-speed printing suitability. Can do.

The applied energy (mJ / dot) referred to in the present specification is applied energy calculated by the following formula (1), and the applied power [W] in the formula (1) is expressed by the following formula (2). Can be calculated.
Applied energy (mJ / dot) = W × LS × PD × tone value (Expression (1))
([W] in (Equation 1) is applied power, [LS] means line cycle (msec./line), [P.D] means pulse duty)
Applied power (W / dot) = V ² / R (formula (2))
([Equation 2] [V] means the applied voltage, [R] means the resistance value of the heating means.)

Hereinafter, various conditions for measuring the tensile strength of the thermal transfer sheet, specifically, the conditions (i) and (ii) may be collectively referred to as “specific conditions”.
Condition (i): The thermal transfer sheet 10 to be measured for tensile strength applies energy to the other surface side of the substrate 1 under the condition of 0.22 mJ / dot, and the color material layer is formed on the transfer target. The point which is the heat transfer sheet which cut out the area | region where the said energy of the heat transfer sheet was applied after shifting the coloring material which 3 contains.
Condition (ii): A tensile test is performed on the thermal transfer sheet satisfying the above condition (i) at a tensile speed of 3 mm / min., And the stress (N) when the cut thermal transfer sheet reaches the yield point is measured. A value obtained by converting this stress per 1 cm width of the cut-out thermal transfer sheet is taken as the tensile strength (N / cm).

The condition for measuring the tensile strength of the thermal transfer sheet is the above “specific condition”. The tensile strength of the thermal transfer sheet that does not satisfy the condition (i) is 2 as the tensile strength calculated by the condition (ii). Even when it is 6 N / cm or more, the tensile strength of the thermal transfer sheet satisfying the above condition (i) must be 2.6 N / cm or more as calculated by the condition (ii). This is because the occurrence of printing wrinkles cannot be sufficiently suppressed. Specifically, the color material layer is contained on the transfer target body by applying energy under a thermal transfer sheet before applying energy or under a condition of less than 0.22 mJ / dot (condition not satisfying condition 1). Even if the tensile strength of the thermal transfer sheet after the color material is transferred is 2.6 N / cm or more in terms of the tensile strength calculated by the condition (ii), When the tensile strength calculated by the “specific condition” is less than 2.6 N / cm, it is because the occurrence of printing wrinkles cannot be sufficiently suppressed.

The stress (N) when the cut-out thermal transfer sheet reaches the yield point is a stress obtained by the following method. Specifically, the thermal transfer sheet to which the color material of the color material layer has been transferred is cut out, and the stress (N) when the cut out thermal transfer sheet is pulled in the length direction under the condition of a tensile speed of 3 mm / min. Measurement is performed using a precision universal testing machine (AGS-100B, Shimadzu Corporation). In the [stress (N) -tensile distance curve] obtained by this measurement, the stress (N) at the first peak is defined as the stress (N) when the yield point is reached.

The specific means for setting the tensile strength of the thermal transfer sheet 10 measured under “specific conditions” to 2.6 N / cm or more is not particularly limited, and for example, the means exemplified below can be applied. In addition, the thermal transfer sheet 10 of one Embodiment is not limited to the following means.

(First means)
The first means is a means for adjusting the tensile strength of the thermal transfer sheet under “specific conditions” to 2.6 N / cm or more by improving the heat resistance of the thermal transfer sheet.

Examples of means for improving the heat resistance of the thermal transfer sheet 10 include (A) the thickness of the base material 1 constituting the thermal transfer sheet 10, the color material layer 3 provided on one surface of the base material 1, and the base material 1. The thickness of an arbitrary layer (for example, a primer layer) provided between the colorant layer 3 and the color material layer 3 and an arbitrary layer (for example, a back layer) provided on the other surface of the base material 1 (B) Examples thereof include a method of selecting a material having high heat resistance as a component of each layer constituting the thermal transfer sheet 10 and the base material 1 constituting the thermal transfer sheet 10. For example, as (B), heat resistance is improved by including a cured resin obtained by curing a resin component with a curing agent in one or a plurality of layers constituting each thermal transfer sheet 10. Can be planned.

In addition, at present, only a measure for improving the heat resistance of only the base material 1 constituting the thermal transfer sheet or improving the heat resistance of one of the layers constituting the thermal transfer sheet is “specific”. It is difficult to set the tensile strength of the thermal transfer sheet to 2.6 N / cm or more in “Conditions of”, and the base material 1 with improved heat resistance and each layer with improved heat resistance are combined with “specific conditions. The tensile strength of the thermal transfer sheet is preferably 2.6 N / cm or more from the viewpoint of material selection. Further, by taking measures combined with the second means described later, the tensile strength of the thermal transfer sheet under “specific conditions” can be 2.6 N / cm or more. Further, when the thickness of the base material 1 and each layer constituting the thermal transfer sheet 10 is increased, it is determined in consideration of the transfer sensitivity of the color material at the time of printing, the small winding diameter of the thermal transfer sheet, and the like. preferable.

(Second means)
The second means is a means for adjusting the tensile strength of the thermal transfer sheet under “specific conditions” to be 2.6 N / cm or more by optimizing the frictional force of the thermal transfer sheet during printing.

In order to optimize the frictional force of the thermal transfer sheet, it is desirable to consider not only the frictional force with the heating member such as the thermal head but also the frictional force between the color material layer 3 and the transfer target during printing. . Even if this is a case where the back surface layer 5 is provided on the other surface of the substrate 1 and the friction force between the back surface layer 5 and the heating member is good, this friction force, When the difference between the frictional force between the color material layer 3 and the transfer material is large, the thermal transfer sheet is damaged during printing, and the tensile strength of the thermal transfer sheet under the “specific conditions” is 2.6 N / cm. This is because it becomes difficult to do this.

As a method for adjusting the frictional force, a release agent is contained in the color material layer 3 provided on one surface of the substrate 1 or an arbitrary back layer 5 provided on the other surface of the substrate 1. Etc.

(Third means)
The third means optimizes the adhesiveness between the base material 1 and the color material layer 3 and the adhesiveness between the base material 1 and the optional back layer 5, and the tensile strength of the thermal transfer sheet under “specific conditions”. Is a means for adjusting to 2.6 N / cm or more. Specifically, it is a means for suppressing the elongation of the substrate during printing by improving the adhesion of each layer constituting the thermal transfer sheet. Examples of the method for optimizing the adhesion include a method of providing a layer for improving the adhesion between the base material 1 and the color material layer 3 (for example, a primer layer described later).

Note that it is currently difficult to adjust the tensile strength of the thermal transfer sheet to “2.6 N / cm” or more under “specific conditions” only by the third means. The third means is the first means, It is preferable to use in combination with the means of 2.

In addition to the above means, for example, the tensile strength of the thermal transfer sheet under “specific conditions” can be adjusted to 2.6 N / cm or more by performing a heat treatment on the substrate 1. The heat treatment for the substrate 1 may be performed once, or may be performed a plurality of times as necessary. As a method of performing the heat treatment a plurality of times on the substrate 1, for example, a method of repeatedly applying and drying the back layer coating liquid when forming the back layer on the other surface of the substrate 1 Can be mentioned. There is no particular limitation on the temperature and time of the heat treatment for the substrate 1, and it may be appropriately set within a range in which the tensile strength of the thermal transfer sheet under “specific conditions” can be adjusted to 2.6 N / cm or more.

Hereinafter, the configuration of the thermal transfer sheet 10 according to an embodiment will be described by way of an example. However, the thermal transfer sheet 10 according to an embodiment may print even when the energy applied to the thermal transfer sheet during printing is increased. The optimal parameters of the thermal transfer sheet that can suppress the generation of wrinkles, that is, the generation of printing wrinkles can be suppressed by setting the tensile strength of the thermal transfer sheet 10 to “2.6 N / cm” or more under “specific conditions”. It is characterized by the point found. Therefore, various means for achieving this characteristic are not limited to the above-described means, and the tensile strength of the thermal transfer sheet 10 under “specific conditions” is set to 2.6 N / cm or more using other means. You can also. Moreover, as long as the conditions that the tensile strength of the thermal transfer sheet 10 under the “specific conditions” is 2.6 N / cm or more are satisfied, the configuration described below may be used.

(Base material)
The base material 1 is an essential configuration in the thermal transfer sheet 10 of one embodiment, and is provided to hold the color material layer 3 provided on one surface of the base material 1. The material of the substrate 1 is not particularly limited, but it is desirable to have mechanical characteristics that can withstand the heat applied when the color material layer 3 is transferred onto the transfer target and does not hinder handling. Examples of such a substrate 1 include polyesters such as polyethylene terephthalate, polyarylate, polycarbonate, polyurethane, polyimide, polyetherimide, cellulose derivatives, polyethylene, ethylene-vinyl acetate copolymer, polypropylene, polystyrene, acrylic, polychlorinated. Vinyl, polyvinylidene chloride, polyvinyl alcohol, polyvinyl butyral, nylon, polyether ether ketone, polysulfone, polyether sulfone, tetrafluoroethylene / perfluoroalkyl vinyl ether, polyvinyl fluoride, tetrafluoroethylene / ethylene, tetrafluoroethylene / hexa Various plastic films such as fluoropropylene, polychlorotrifluoroethylene, and polyvinylidene fluoride Mention may be made of the beam or sheet.

Further, the substrate 1 may be subjected to a surface treatment. Examples of the surface treatment method include corona discharge treatment, flame treatment, ozone treatment, ultraviolet treatment, radiation treatment, surface roughening treatment, chemical treatment, plasma treatment, low temperature plasma treatment, grafting treatment and the like. .

The thickness of the substrate 1 is not particularly limited, and is usually in the range of 2.5 μm to 100 μm, and preferably in the range of 4 μm to 6 μm. In addition, in order to adjust the tensile strength of the thermal transfer sheet 10 under the above “specific conditions” to 2.6 N / cm or more, the thickness can be made larger than this. For example, the thickness of the base material 1 can be set to a thickness exceeding 100 μm. Although there is no limitation in particular about the upper limit of thickness, it is about 200 micrometers.

(Color material layer)
As shown in FIGS. 1 to 3, a color material layer 3 is provided on the base material 1. The color material layer 3 is an essential component in the thermal transfer sheet 10 of one embodiment, and contains a color material component and a binder resin. The color material layer 3 may be provided directly on the base material 1 as shown in FIG. 1, and as shown in FIG. 2, another layer (primer layer in the illustrated form) is provided on the base material 1. It may be provided indirectly via.

The color material component contained in the color material layer 3 is not particularly limited, but preferably has a sufficient color density and does not discolor due to light, heat, temperature, or the like. Examples of such colorant components include diarylmethane dyes, triarylmethane dyes, thiazole dyes, merocyanine dyes, pyrazolone dyes, methine dyes, indoaniline dyes, pyrazolomethine dyes, acetophenone azomethine, and pyrazolo dyes. Azomethine dyes such as azomethine, imidazolazomethine, imidazoazomethine and pyridone azomethine, xanthene dyes, oxazine dyes, cyanostyrene dyes such as dicyanostyrene and tricyanostyrene, thiazine dyes, azine dyes, acridine dyes, Benzene azo dyes, pyridone azo, thiophenazo, isothiazole azo, pyrrole azo, pyrazole azo, imidazole azo, thiadiazole azo, triazole azo, disazo azo dyes, spiropyran dyes , India Linos Piropi run dyes, fluoran dye, rhodamine lactam-based dyes, naphthoquinone dyes, anthraquinone dyes, quinophthalone dyes, and the like. Specifically, red dyes such as MSRedG (Mitsui Toatsu Chemicals), Macrolex Red Violet R (Bayer), CeresRed 7B (Bayer), Samalon Red F3BS (Mitsubishi Chemical), etc., Holon Brilliant Yellow Yellow dyes such as 6GL (Clariant), PTY-52 (Mitsubishi Chemical Corporation), Macrolex Yellow 6G (Bayer), Kayaset (registered trademark) Blue 714 (Nippon Kayaku Co., Ltd.), Holon Brilliant Blue S -R (Clariant), MS Blue 100 (Mitsui Toatsu Chemicals), C.I. I. And blue dyes such as Solvent Blue 63.

The binder resin contained in the color material layer 3 is not particularly limited, and examples thereof include cellulose resins such as ethyl cellulose resin, hydroxyethyl cellulose resin, ethyl hydroxy cellulose resin, methyl cellulose resin, and cellulose acetate resin, polyvinyl alcohol resin, and polyacetic acid. Examples include vinyl resins, polyvinyl butyral resins, polyvinyl acetal resins, vinyl resins such as polyvinyl pyrrolidone, acrylic resins such as poly (meth) acrylate and poly (meth) acrylamide, polyurethane resins, polyamide resins, and polyester resins. be able to. Among these, cellulose-based, vinyl-based, acrylic-based, polyurethane-based, and polyester-based resins are preferable in terms of heat resistance, colorant component migration, and the like.

Further, as the binder resin, a binder resin obtained by curing the binder resin exemplified above with various curing agents such as isocyanate, epoxy resin, and carbodiimide may be used. By including the cured binder resin in the color material layer 3, it is possible to improve the heat resistance of the color material layer 3 and to adjust the frictional force between the color material layer 3 and the transfer target during printing.

The content of the color material component contained in the color material layer 3 is not particularly limited, and may be appropriately set according to the color material component used and the type of the binder resin in consideration of print density, storage stability, and the like. That's fine. The content of the color material component as an example is in the range of 15% by mass or more and 300% by mass or less with respect to the total mass of the binder resin contained in the color material layer 3.

Moreover, the color material layer 3 may contain an arbitrary additive together with the color material component and the binder resin. Examples of optional additives include inorganic fine particles and organic fine particles. Examples of the inorganic fine particles include carbon black, silica, alumina, titanium dioxide, molybdenum disulfide and the like. Examples of the organic fine particles include polyethylene wax.

Further, by incorporating a release agent into the color material layer 3 and adjusting the frictional force between the color material layer 3 and the transfer target, the tensile strength of the thermal transfer sheet under “specific conditions” is 2.6 N / cm. It can also adjust so that it may become above. Examples of the release agent include silicone oil, phosphate ester, and fluorine-based material. There is no particular limitation on the content of the release agent, and any frictional force between the color material layer 3 and the transfer target and the other surface side of the base material, for example, the other side of the base material 1 during printing. It may be determined in consideration of the balance between the back layer 5 and the frictional force between the heating member such as the thermal head.

The method for forming the color material layer 3 is not particularly limited, and the color material component, the binder resin, and various additives added as necessary may be toluene, methyl ethyl ketone, ethanol, isopropyl alcohol, cyclohexane, dimethylformamide, water, or the like. A colorant layer coating solution dispersed or dissolved in an appropriate solvent is prepared, and this coating solution is formed by applying and drying the base material 1 or an arbitrary layer provided on the base material. be able to. There is no limitation in particular about the coating method of the coating liquid for color material layers, A conventionally well-known coating method can be selected suitably and can be used. Examples of the coating method include a gravure printing method, a screen printing method, a reverse coating method using a gravure plate, and the like. Moreover, the coating method other than this can also be used. This is the same also about the coating method of the various coating liquid mentioned later.

The thickness of the color material layer 3 is not particularly limited, and is usually in the range of 0.2 μm to 10 μm, but the tensile strength of the thermal transfer sheet under “specific conditions” is 2.6 N / cm or more. In order to adjust, the thickness can be made thicker than 10 μm.

As shown in FIGS. 1 and 2, the thermal transfer sheet 10 of one embodiment may be one in which one color material layer 3 is provided on a base material 1, and as shown in FIG. A plurality of color material layers having different hues (in the illustrated form, the color material layer 3Y, the color material layer 3M, and the color material layer 3C) may be provided on the same surface of the material 1. In the thermal transfer sheet provided with a plurality of color material layers, when the thermal transfer image is formed using one color material layer of the plurality of color material layers, the tension of the thermal transfer sheet 10 under the above-mentioned “specific conditions” It is sufficient that the strength is 2.6 N / cm or more. However, when a thermal transfer image is formed in any color material layer of the plurality of color material layers, the thermal transfer sheet 10 under the “specific conditions” described above. It is preferable that the tensile strength of is 2.6 N / cm or more.

(Primer layer)
As shown in FIG. 2, a primer layer 8 can be provided between the base material 1 and the color material layer 3. By providing the primer layer 8, the adhesion between the base material 1 and the color material layer 3 can be improved, and the occurrence of abnormal transfer that causes the transfer target and the color material layer 3 to stick together during printing is sufficient. Can be suppressed.

Examples of the components of the primer layer 8 include polyester resins, polyacrylate resins, polyvinyl acetate resins, polyurethane resins, styrene acrylate resins, polyacrylamide resins, polyamide resins, polyether resins, Examples thereof include polystyrene resins, polyethylene resins, polypropylene resins, vinyl resins such as polyvinyl chloride resins and polyvinyl alcohol resins, polyvinyl acetal resins such as polyvinyl acetoacetal and polyvinyl butyral, and the like. Of these, polyurethane resins and the like are suitable.

Also, the primer layer 8 can be composed of fine particles derived from colloidal inorganic particles. According to the primer layer 8 of this form, not only can the abnormal transfer of the color material layer 3 be prevented during printing, but also the migration of the color material component from the color material layer 3 to the primer layer 8 can be suppressed. Specifically, it is possible to effectively diffuse the color material component to the transferred body side and to increase the print density of the formed thermal transfer image.

Conventionally known compounds can be used as the colloidal inorganic particles. For example, silica (colloidal silica), alumina or alumina hydrate (alumina sol, colloidal alumina, cationic aluminum oxide or hydrate, pseudoboehmite, etc.), aluminum silicate, magnesium silicate, magnesium carbonate, magnesium oxide, oxidation Examples include titanium. In particular, colloidal silica and alumina sol are preferably used. These colloidal inorganic particles have a primary average particle size of 100 nm or less, preferably 50 nm or less, and particularly preferably in the range of 3 nm to 30 nm.

The primer layer 8 is prepared by preparing a primer layer coating solution prepared by dissolving or dispersing the components exemplified above and colloidal inorganic particles in an appropriate solvent, and applying and drying the coating solution on the substrate 1. Can be formed. The thickness of the primer layer 8 is not particularly limited and is usually in the range of 0.02 μm to 1 μm, but the primer layer 8 is made thicker than 1 μm to improve the durability of the primer layer 8. You can also.

(Back layer)
A back layer 5 can also be provided on the other surface of the substrate 1. Examples of the resin component of the back layer include polyester resins, polyacrylate resins, polyvinyl acetate resins, styrene acrylate resins, polyurethane resins, polyethylene resins, polypropylene resins, and other polyolefin resins, polystyrene Resins, polyvinyl chloride resins, polyether resins, polyamide resins, polyimide resins, polyamideimide resins, polycarbonate resins, polyacrylamide resins, polyvinyl chloride resins, polyvinyl butyral resins, polyvinyl acetoacetal resins, etc. Examples thereof include thermoplastic resins such as acetal resin, and silicone modified products thereof. Specifically, polyvinyl butyral resin, polyvinyl acetoacetal resin, polyester resin, vinyl chloride-vinyl acetate copolymer, polyether resin, polybutadiene resin, styrene-butadiene copolymer, acrylic polyol, polyurethane acrylate, polyester acrylate, poly Ether acrylate, epoxy acrylate, urethane or epoxy prepolymer, nitrocellulose resin, cellulose nitrate resin, cellulose acetopropionate resin, cellulose acetate butyrate resin, cellulose acetate hydrodiene phthalate resin, cellulose acetate resin, aromatic polyamide resin , Polyimide resin, polyamideimide resin, polycarbonate resin, chlorinated polyolefin resin, and the like.

Also, a resin component obtained by curing a resin component with a curing agent can be used. Examples of the curing agent include an isocyanate curing agent. By setting it as the back surface layer 5 containing the resin component hardened | cured with the hardening | curing agent, durability of the back surface layer 5 can be improved.

The back layer 5 may contain an arbitrary additive together with the resin component. Optional additives include, for example, phosphoric acid esters, fatty acid esters, metal soaps, Wax, silicone oil, graphite powder, silicone-based graft polymers, fluorine-based graft polymers, acrylic silicone graft polymers, silicones such as acrylic siloxane and aryl siloxane. A polymer can be mentioned. By setting it as the back surface layer 5 containing these additives, the back surface layer 5 can be provided with favorable lubricity. For example, the thermal transfer sheet 10 under “specific conditions” is optimized by optimizing the frictional force between the back surface layer 5 and the heating member in the relationship between the colorant layer 3 and the frictional force between the transferred material during printing. The tensile strength of can be adjusted to 2.6 N / cm or more.

The method for forming the back layer is not particularly limited. The resin component exemplified above, an additive added as necessary, is prepared by dissolving or dispersing a coating solution in a suitable solvent, It can be formed by applying and drying on the substrate 1. The thickness of the back layer 5 is usually in the range of 0.1 μm or more and 3 μm or less, but in order to adjust the tensile strength of the thermal transfer sheet 10 under “specific conditions” to 2.6 N / cm or more, the thickness is larger than this thickness. Can also be made thicker.

(Back primer layer)
Further, a back primer layer (not shown) can be provided between the substrate 1 and the back layer 5. The back primer layer is a layer provided in order to improve the adhesion between the substrate 1 and the back layer 5 and is an arbitrary layer. Examples of the back primer layer include polyester resin, polyurethane resin, acrylic resin, polycarbonate resin, polyamide resin, polyimide resin, polyamideimide resin, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral resin, polyvinyl alcohol resin, and polyvinylpyrrolidone resin. Etc. Moreover, you may contain the electrically conductive material for providing electroconductivity suitably. Examples thereof include sulfonated polyaniline, carbon particles, silver particles, and gold particles.

(Transfer material)
There is no particular limitation on the transfer target used in printing using the thermal transfer sheet of one embodiment, and examples thereof include conventionally known materials such as plain paper, high-quality paper, tracing paper, plastic film, and thermal transfer image receiving sheet.

(Printer)
There is no particular limitation on the printer used when the color material component contained in the color material layer 3 is transferred onto the transfer target using the thermal transfer sheet 10 of one embodiment, and a conventional printer provided with a heating member such as a thermal head. Any known printer can be used. Note that the thermal transfer sheet 10 according to the embodiment can sufficiently suppress the occurrence of printing wrinkles even when a printer capable of applying high energy is used, and is particularly suitable when using a printer capable of applying high energy. Is preferred.

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

Example 1
A polyethylene terephthalate film 1 having a thickness of 5.7 μm is prepared as a substrate, and a primer layer coating solution having the following composition is formed on one surface of the substrate so that the thickness when dried is 0.3 μm. The primer layer was formed by coating and drying. Next, on the primer layer, a yellow color material layer coating liquid having the following composition, a magenta color material layer coating liquid having the following composition, and a cyan color material layer coating liquid having the following composition each having a thickness when dried. The yellow color material layer, the magenta color material layer, and the cyan color material layer were formed in the order of 0.6 μm by coating and drying in order. Further, the back layer coating liquid 1 having the following composition is applied and dried on the other surface of the base material so that the thickness when dried is 1 μm to form a back layer, whereby the thermal transfer of Example 1 is performed. A sheet was obtained.

<Primer layer coating solution>
Alumina sol (primary average particle size 10 × 100 nm (solid content 10%))
30 parts (Alumina sol 200 Nissan Chemical Industries, Ltd.)
・ 3 parts of polyvinylpyrrolidone resin (K-90 ISP)
・ Water 50 parts ・ Isopropyl alcohol 17 parts

<Coating solution for yellow color material layer>
-Solvent Yellow 93 2 parts-Disperse Yellow 231 2 parts-Polyvinyl acetal resin 3 parts (ESREC (registered trademark) KS-5 Sekisui Chemical Co., Ltd.)
・ Polyethylene wax 0.1 part ・ Methyl ethyl ketone 45 parts ・ Toluene 45 parts

<Coating liquid for magenta color material layer>
・ Disperse dye (MS Red G) 1.5 parts ・ Disperse dye (Macrolex Red Violet R) 2 parts ・ Polyvinyl acetal resin 4.5 parts (ESREC (registered trademark) KS-5 Sekisui Chemical Co., Ltd.)
・ Polyethylene wax 0.1 part ・ Methyl ethyl ketone 45 parts ・ Toluene 45 parts

<Cyan color material layer coating solution>
・ Solvent Blue 63 2 parts ・ Disperse Blue 354 2 parts ・ Polyvinyl acetal resin 3.5 parts (ESREC (registered trademark) KS-5 Sekisui Chemical Co., Ltd.)
・ Polyethylene wax 0.1 part ・ Methyl ethyl ketone 45 parts ・ Toluene 45 parts

<Back layer coating liquid 1>
・ 4.55 parts of polyvinyl butyral resin (ESREC (registered trademark) BX-1 Sekisui Chemical Co., Ltd.)
-Polyisocyanate (solid content 45%) 21 parts (Bernock (registered trademark) D750-45 DIC Corporation)
・ Phosphate surfactant 3 parts (Pricesurf (registered trademark) A208N Daiichi Kogyo Seiyaku Co., Ltd.)
-0.7 parts of talc (Microace (registered trademark) P-3 Nippon Talc Industry Co., Ltd.)
・ Methyl ethyl ketone 100 parts ・ Toluene 100 parts

(Example 2)
A thermal transfer sheet of Example 2 was obtained in the same manner as Example 1 except that a polyethylene terephthalate film 2 having a thickness of 5.2 μm was used instead of the polyethylene terephthalate film 1.

(Example 3)
A thermal transfer sheet of Example 3 was obtained in the same manner as in Example 1 except that a polyethylene terephthalate film 3 having a thickness of 4.6 μm was used instead of the polyethylene terephthalate film 1.

(Example 4)
Implemented except that polyethylene terephthalate film 4 with a thickness of 4.85 μm was used instead of polyethylene terephthalate film 1 and coating solution 1 for the back layer was applied and dried to a thickness of 2 μm when dried. A thermal transfer sheet of Example 4 was obtained in the same manner as Example 1.

(Example 5)
Using the polyethylene terephthalate film 4 as a base material, a primer layer coating solution having the above composition is applied and dried on one surface of the base material so that the thickness upon drying is 0.3 μm. A layer was formed. Next, on the primer layer, the yellow color material layer coating liquid having the above composition, the magenta color material layer coating liquid having the above composition, and the cyan color material layer coating liquid having the above composition each having a thickness when dried. The yellow color material layer, the magenta color material layer, and the cyan color material layer were formed by coating and drying in order of 0.6 μm. Also, on the other surface of the base material, the back layer coating liquid 1 having the above composition is applied and dried so as to have a dry thickness of 1 μm to form a first back layer, and this first back layer The thermal transfer sheet of Example 5 was obtained by applying and drying the back layer coating liquid 1 having the above composition so that the thickness upon drying was 1 μm to form a second back layer.

(Comparative Example 1)
A thermal transfer sheet of Comparative Example 1 was obtained in the same manner as Example 1 except that a polyethylene terephthalate film 5 having a thickness of 5 μm was used instead of the polyethylene terephthalate film 1.

(Comparative Example 2)
A thermal transfer sheet of Comparative Example 2 was obtained in the same manner as in Example 1 except that the polyethylene terephthalate film 4 was used instead of the polyethylene terephthalate film 1.

(Comparative Example 3)
Example 1 except that the polyethylene terephthalate film 4 was used in place of the polyethylene terephthalate film 1 and the back layer coating solution 1 was applied and dried so that the thickness when dried was 1.4 μm. Similarly, a thermal transfer sheet of Comparative Example 3 was obtained.

(Evaluation of printing wrinkles)
The thermal transfer sheet of each of the examples and comparative examples obtained above and the thermal transfer image receiving sheet (image receiving sheet dedicated to sublimation printer DS620 (Dai Nippon Printing Co., Ltd.)) were combined, and the following test printer was used for thermal transfer image receiving Using the yellow color material layer, the magenta color material layer, and the cyan color material layer of the thermal transfer sheet of each of the examples and the comparative example as a starting point at the center in the width direction of the sheet, 50% of the width direction is used. An image (0/255 gradation) was printed, the occurrence of printing wrinkles in the formed black solid image was visually confirmed, and the printing wrinkles were evaluated based on the following evaluation criteria. It should be noted that printing is not performed in the other 50% region in the width direction of the thermal transfer image-receiving sheet, and the evaluation of the main print wrinkle is an evaluation under the condition that the print wrinkle is likely to occur in the black solid image.

(Test printer)
-Heating element average resistance: 5241 (Ω)
・ Print density in main scanning direction: 300 (dpi)
-Sub-scanning direction printing density: 300 (dpi)
・ Printing energy: 0.22 (mJ / dot)
Line cycle: 2 (msec./line)
・ Pulse duty: 85 (%)

"Evaluation criteria"
A: Wrinkles are not generated in the solid black image.
NG: Wrinkles are generated in the black solid image.

(Measurement of tensile strength)
The thermal transfer sheet corresponding to the magenta color material layer portion used for the formation of the black solid image is 18 mm in width and length for each of the examples and comparative examples after the evaluation of the printing wrinkles. Cut out to 80 mm, the stress (N) when the cut out thermal transfer sheet was pulled in the length direction under the condition of a pulling speed of 3 mm / min. Was measured using a precision universal testing machine (AGS-100B, Shimadzu Corporation). And measured. Next, in the [stress (N) -tensile distance curve] obtained by measurement, the stress (N) that becomes the first peak is the stress (N) when the yield point is reached, and this stress (N) is cut out. The tensile strength (N / cm) was calculated by dividing by the width of the thermal transfer sheet. The calculation results are shown in Table 1.

DESCRIPTION OF SYMBOLS 1 ...

Base material

3, 3Y, 3M, 3C ... Color material layer 5 ... Back surface layer 8 ... Primer layer 100 ... Thermal transfer sheet

Claims

A thermal transfer sheet provided with a color material layer containing a color material on one surface of a substrate,
The thermal transfer sheet applies energy to the other surface side of the base material under the condition of 0.22 mJ / dot to transfer the color material contained in the color material layer onto the transfer target, A region of the thermal transfer sheet to which the energy was applied was cut out, and when the tensile test was performed on the cut out thermal transfer sheet at a tensile speed of 3 mm / min., The cut out thermal transfer sheet reached the yield point. The thermal transfer sheet is characterized in that the tensile strength converted from the stress (N) per 1 cm width of the cut-out thermal transfer sheet is 2.6 N / cm or more.