JP6745052B2 - Laminated body and manufacturing method thereof - Google Patents

Description

The present invention relates to a laminate and a method for manufacturing the same.

An IC card or a card used in a card game or the like uses a stealth ink layer (information that is unique to the card is recorded using ink that absorbs invisible rays such as infrared rays) and can be read by a specific device ( A laminate having a code pattern) is used (Patent Document 1).

When observing a card or laminated body on which a stealth ink layer is formed from their surface, the unevenness due to the stealth ink layer is visually observed even though an image is printed on the surface of the card. , There was a problem that the card was forged or modified.

In order to solve the above problems, it has been proposed to form a concealing layer on the stealth ink layer so that information cannot be easily read (see Patent Document 2).

However, if the concealing layer is simply formed, the unevenness due to the stealth ink layer is still observed, and the position and shape of the code pattern are recognized.

Furthermore, the image information on the outer surface of the laminate disclosed in Patent Document 1 is formed by using offset printing or the like, and is not suitable for on-demand production.

JP, 2004-155081, A JP-A-58-45999

The present invention has been made in view of such a situation, and it is possible to make it difficult to recognize the unevenness of the laminate surface due to the stealth ink layer, and further prevent forgery and modification. The main object of the present invention is to provide a laminate that can be manufactured and a manufacturing method thereof. Another object is to provide a laminate suitable for on-demand production.

The laminate according to the present invention,
Transfer target,
A stealth ink layer comprising an invisible light absorbing material on the transferred material,
A transfer layer and a hiding layer on the stealth ink layer,
Is equipped with
The hiding layer has a thickness of 4 times or more the thickness of the stealth ink layer, and the hiding layer includes a hiding layer.

In the above aspect, it is preferable that the hiding layer comprises a receiving layer provided on the hiding layer.

In the above aspect, it is preferable that the hiding layer comprises a protective layer provided on the receiving layer.

In the above aspect, the color of the stealth ink layer and the color of the shielding layer are preferably similar colors.

The method for producing the laminate according to the present invention,
A step of preparing a transfer target,
A step of forming a stealth ink layer containing an invisible light absorbing material on the transferred material,
And a step of forming a concealing layer on the transferred material and the stealth ink layer.

In the above aspect, it is preferable that the step of forming the concealing layer includes a step of forming a shielding layer on the transferred material and the stealth ink layer.

In the above aspect, it is preferable that the step of forming the concealing layer includes a step of forming a receiving layer on the shielding layer and a step of forming an image on the receiving layer.

In the above aspect, it is preferable that the step of forming the concealing layer includes the step of forming a protective layer on the image receiving layer on which the image is formed.

In the above aspect, it is preferable that the stealth ink layer is formed by using the gradation printing method.

According to the present invention, it is possible to make it difficult to recognize the unevenness on the surface of the laminate due to the stealth ink layer, and it is possible to further prevent counterfeiting or modification. In addition, the layered product according to the present invention is suitable for on-demand printing because each layer provided can be formed by thermal fusion transfer or sublimation transfer.

It is a figure which shows the laminated body of this invention in one embodiment. It is a figure which shows the laminated body of this invention in one embodiment. It is a cross-sectional schematic diagram of the thermal transfer sheet in one embodiment.

(Laminate)
The laminate 10 according to the present invention, as shown in FIG.
Transfer target 11,
A stealth ink layer 12 containing an invisible light absorbing material on the transferred body 11,
A transfer layer 11 and a hiding layer 13 on the stealth ink layer 12,
Is equipped with
It is characterized in that the thickness of the hiding layer 13 is four times or more the thickness of the stealth ink layer 12.

In one embodiment, as shown in FIG. 2, the hiding layer 13 comprises a hiding layer 14, a receiving layer 15 and a protective layer 16.

Hereinafter, each layer included in the laminated body will be described in detail.

(Transfer material)
In one embodiment, the transferred material used in the method of the present invention is natural fiber paper, fine paper, art paper, lightweight coated paper, lightly coated paper, coated paper, cast coated paper, synthetic resin or emulsion impregnated paper. , Tracing paper, plastic film, glass, metal, ceramics, wood, cloth, etc., and may be composed of a single layer or plural layers.

When the transferred material is a plastic film, examples of the plastic film include polyester such as polyethylene terephthalate, polycarbonate, polyimide, polyetherimide, cellulose derivative, polyethylene, polypropylene, polystyrene, acrylic, polyvinyl chloride, polyvinylidene chloride, Examples include various plastic films or sheets such as nylon and polyether ether ketone.
The plastic film may be a copolymer resin or a mixture (including alloy) containing the above resin as a main component.

Further, the transferred material may be provided with a receiving layer on one surface or both surfaces thereof, and as will be described later, an image may be formed on the surface opposite to the surface on which the stealth ink layer is provided. Good.

The thickness of the transferred material is not particularly limited, but is preferably 3 μm or more and 800 μm, and more preferably 100 μm or more and 600 μm or less.

(Stealth ink layer)
In one embodiment, the stealth ink layer forms a code pattern capable of reading information unique to the laminate by using an optical reading device using infrared rays or ultraviolet rays.
It is particularly preferable that the stealth ink layer is subjected to melt heat transfer using an image corrected by a gradation printing method such as a dither method. This makes it possible to blur the contour of the stealth ink layer, make it more difficult to recognize the shape of the stealth ink layer, and further prevent counterfeiting or modification.

The stealth ink layer comprises an invisible light absorbing material. Examples of the invisible light absorbing material include an infrared absorbing material and an ultraviolet absorbing material.
In the present specification, infrared rays have a maximum absorption wavelength (λmax) region of 700 to 1000 nm. In addition, the ultraviolet ray means that the maximum absorption wavelength (λmax) region is 280 to 400 nm.

The content of the invisible light absorbing material in the stealth ink layer is preferably 1% by mass or more and 60% by mass or less, more preferably 5% by mass or more and 40% by mass or less. By setting the content of the invisible light absorbing material in the above numerical range, it is possible to achieve both the transferability of the code pattern and the reading of the information peculiar to the laminate when the stealth ink layer is thermally melt transferred.

Examples of the infrared absorbing material include diimonium compounds, aminium compounds, phthalocyanine compounds, dithiol organometallic complexes, cyanine compounds, azo compounds, polymethine compounds, quinone compounds, diphenylmethane compounds, triphenylmethane compounds. Examples of such compounds include oxole compounds and carbon black. The stealth ink layer may include one or more infrared absorbing materials as described above.

Examples of the ultraviolet absorbing material include organic ultraviolet absorbing materials such as benzotriazole compounds, triazine compounds, benzophenone compounds, and benzoate compounds, and inorganic ultraviolet rays such as titanium oxide, zinc oxide, cerium oxide, iron oxide, and barium sulfate. Absorption materials may be mentioned, and the stealth ink layer may contain one or more of the above-mentioned ultraviolet absorption materials.

The stealth ink layer may include a binder resin. As the binder resin, for example, polyester resin, fluorine resin, polystyrene resin, acrylic resin, cellulose resin, polycarbonate resin, polyamide resin, polyvinyl chloride resin, polyvinyl acetate resin, polypropylene resin, etc. The known resins such as polyolefin resin, polyvinyl alcohol resin, polyvinylpyrrolidone resin, polyimide resin, phenol resin and polyurethane resin, and copolymers thereof can be mentioned.
The content of the binder resin in the stealth ink layer is preferably 40% by mass or more and 99% by mass or less, and more preferably 60% by mass or more and 95% by mass or less.

The thickness of the stealth ink layer is preferably 0.1 μm or more and 5 μm or less, and more preferably 0.3 μm or more and 2 μm or less.

(Hiding layer)
The concealment layer is a layer formed on the transferred material and the stealth ink layer, and has a thickness four times or more that of the stealth ink layer.
By setting the relationship between the thickness of the concealing layer and the thickness of the stealth ink layer as described above, it is possible to make it difficult to recognize the unevenness on the surface of the laminate due to the stealth ink layer.
Therefore, it is possible to make it difficult to recognize the position and shape of the code pattern formed by the stealth ink layer, and further prevent counterfeiting or modification. More preferably, the thickness of the hiding layer is 4.5 times or more, and even more preferably 5 times or more the thickness of the stealth ink layer. In addition, the thickness of the hiding layer is preferably 100 times or less the thickness of the stealth ink layer from the viewpoint of good thermal transfer without the problem of foil breakage.

The hiding layer may be a single-layered layer or a multi-layered layer.
In one embodiment, the hiding layer comprises the hiding layer described below.
Also, in one embodiment, the hiding layer comprises a hiding layer and a receiving layer in that order.
Also, in one embodiment, the hiding layer comprises a shielding layer, a receiving layer and a protective layer in this order.
Further, the hiding layer may include a primer layer between the shielding layer and the receiving layer and/or between the receiving layer and the protective layer.
Furthermore, the hiding layer may include a release layer.

(Shielding layer)
The hiding layer included in the laminate according to the present invention may include a hiding layer.
This shielding layer is preferably non-absorbent of invisible light.
The color of the shielding layer is preferably similar to the color of the stealth ink layer. This makes it difficult to recognize the position and shape of the code pattern formed by the stealth ink layer, and can further prevent counterfeiting or modification.
In this specification, similar colors mean colors having the same or similar hue and/or brightness, saturation, and/or glossiness. For example, silver and gray are similar colors.
More specifically, the color difference (ΔE*ab) between the shielding layer and the stealth ink layer is preferably 5 or less, more preferably 3 or less, and even more preferably 1 or less.
The color difference (ΔE*ab) is, for example, measured by using a spectrophotometer (manufactured by Gretag Macbeth, trade name: spectorino), and is a value in the L*a*b* color system of the International Certification Committee To define. The value is represented by ΔE*ab=((ΔL*) ² +(Δa*) ² +(Δb*) ² ) ^1/2 , and the larger the value, the more remarkable the color difference when viewed. It should be noted that (ΔL*), (Δa*), and (Δb*) are differences in the values of L*, a*, and b* between the stealth ink layer and the shielding layer.

The shielding layer can comprise a colorant. The colorant is not particularly limited, and pigments or dyes such as white, silver, black, cyan, magenta and yellow, and metal powder can be used.
In addition, the shielding layer may contain an invisible light absorbing colorant as long as the object of the present invention is not impaired. For example, when the stealth ink layer contains an infrared absorbing material as the invisible light absorbing material, the shielding layer may contain an ultraviolet absorbing colorant.
The content of the colorant in the shielding layer is preferably 2 parts by mass or more and 500 parts by mass or less, and preferably 5 parts by mass or more and 450 parts by mass or less with respect to the total solid amount of the binder resin in the shielding layer described later. Is more preferable.

The shielding layer can include a resin similar to the binder resin included in the stealth ink layer.
The content of the binder resin in the shielding layer is preferably 15% by mass or more and 99% by mass or less, and more preferably 18% by mass or more and 96% by mass or less based on the total solid amount of the hiding layer.

The thickness of the shielding layer is preferably 0.05 μm or more and 5 μm or less, and more preferably 0.2 μm or more and 3 μm or less.

(Receptive layer)
The hiding layer provided in the laminate according to the present invention can comprise a receiving layer.
The receiving layer is preferably non-absorbent of invisible light.
As a material for forming the receiving layer, a conventionally known resin material that easily accepts a heat-transferable coloring material such as a sublimable dye or a hot-melt ink can be used. For example, polyolefin resin such as polypropylene, halogenated resin such as polyvinyl chloride or polyvinylidene chloride, polyvinyl acetate, vinyl chloride-vinyl acetate polymer, ethylene-vinyl acetate copolymer or vinyl such as polyacrylic acid ester. -Based resin, polyester-based resin such as PET or PBT, polystyrene-based resin, polyamide-based resin, copolymer-based resin of olefin such as ethylene or propylene and other vinyl polymer, cellulose-based resin such as ionomer or cellulose diastase, polycarbonate, etc. Among these, vinyl chloride-vinyl acetate-based polymers or polyvinyl chloride resins are preferable, and vinyl chloride-vinyl acetate-based polymers are particularly preferable.

The thickness of the receiving layer is preferably 0.2 μm or more and 10 μm or less, more preferably 0.5 μm or more and 5 μm or less.

(Protective layer)
The concealing layer included in the laminate according to the present invention can include a protective layer.
The protective layer is preferably non-absorbent of invisible light rays.
As the material for forming the protective layer, for example, polyester resin, polycarbonate resin, vinyl resin, acrylic resin, polystyrene resin, urethane resin, epoxy resin, polyamide resin, these resins are modified with silicone. Examples of the resin include a cured resin and an actinic ray curable resin.
In the present specification, the actinic ray-curable resin means a precursor or a composition before being irradiated with actinic rays, and the actinic ray-curable resin is irradiated with actinic rays to cure the actinic rays. It is called a cured resin.

The thickness of the protective layer is preferably 0.2 μm or more and 10 μm or less, more preferably 0.3 μm or more and 5 μm or less.

(Primer layer)
The hiding layer provided in the laminate according to the present invention can comprise a receiving layer.
The primer layer is preferably non-absorbent of invisible light.

The primer layer can contain a resin similar to the binder resin contained in the stealth ink layer.
Further, the primer layer may contain inorganic fine particles, for example, silica (corodyl silica), alumina or alumina hydrate (alumina sol, colodyl alumina, cationic aluminum oxide or its hydrate), aluminum silicate, Examples thereof include magnesium silicate, magnesium carbonate, magnesium oxide and titanium oxide.
The average particle diameter of the inorganic fine particles is preferably 0.01 μm or more and 5 μm or less. The average particle size of the inorganic fine particles is more preferably 0.01 μm or more and 3 μm or less. The “average particle diameter” means a volume average particle diameter, and is measured by a known method using a particle size distribution/particle size distribution measuring device (for example, Nanotrac particle size distribution measuring device, manufactured by Nikkiso Co., Ltd.). can do.

The thickness of the primer layer is preferably 0.02 μm or more and 6 μm or less, and more preferably 0.04 μm or more and 4 μm or less.

(Peeling layer)
The concealing layer included in the laminate according to the present invention can include a release layer.
In the present specification, the release layer refers to a layer that is transferred onto a transfer target together with the stealth ink layer and the like during thermal transfer.
The release layer is preferably non-absorbent of invisible light.

The release layer can include a binder resin and a release material.
Examples of the binder resin include acrylic resins, vinyl resins, cellulose resins, polyester resins, polyurethane resins and the like.
Examples of the releasable material include waxes, silicone waxes, silicone resins, melamine resins, talc, silica and surfactants.

The thickness of the peeling layer is preferably 0.2 μm or more and 10 μm or less, and more preferably 0.4 μm or more and 5 μm or less.

(Method for manufacturing laminated body)
The manufacturing method of the laminate according to the present invention,
A step of preparing a transfer target,
A step of forming a stealth ink layer containing an invisible light absorbing material on the transferred material,
And a step of thermally transferring the concealing layer onto the transferred material and the stealth ink layer.
Hereinafter, each of the above steps will be described in detail.

(Step of preparing transfer target)
The transferred material used for manufacturing the laminate is as described above.

(Stealth ink layer forming process)
The stealth ink layer can be formed by melt-thermal transfer of the stealth ink layer on the thermal transfer sheet onto the transfer target provided in the laminate.

(Hiding layer forming process)
The hiding layer can be formed by melt heat transfer of the hiding layer on the thermal transfer sheet onto the transfer target and the stealth ink layer provided in the laminate.

In one embodiment, the step of forming the concealing layer comprises a step of forming a shielding layer on the transferred material and the stealth ink layer.
Also, in one embodiment, the step of forming the concealing layer comprises the step of forming a receiving layer on the shielding layer.
Also, in one embodiment, the method comprises forming an image on the receiving layer.
In one embodiment, it also comprises the step of forming a protective layer on the imaged receiving layer.
Further, in one embodiment, the step of forming the concealing layer may include the step of forming a primer layer between the shielding layer and the receiving layer or between the receiving layer and the protective layer.
In addition, in one embodiment, the step of forming the concealing layer may include the step of forming a release layer.

The shielding layer, the receiving layer, the protective layer and the primer layer can be formed by thermal transfer, preferably melt thermal transfer, of the receiving layer on the thermal transfer sheet onto the concealing layer included in the laminate.
The image can be formed on the receptor layer by sublimation heat transfer of the dye layer on the thermal transfer sheet onto the receptor layer of the laminate. In the present specification, the image includes not only a design but also characters and the like.
Further, in one embodiment, processing such as pressing a gold-silver foil or attaching a hologram may be performed on the image-receiving layer.
Further, in one embodiment, an image may be formed on the surface of the transfer-receiving body opposite to the surface on which the stealth ink layer or the like is formed.
The peeling layer can be formed by heat-melt transfer of the stealth ink layer and the like on the heat transfer sheet together with the stealth ink layer and the like.

(Thermal transfer sheet)
In one embodiment, the formation of the stealth ink layer and the like included in the above-mentioned laminated body is performed using a thermal transfer sheet.
As shown in FIG. 3, the thermal transfer sheet 20 is provided with a base material 21, a stealth ink layer 12, and a shielding layer 14 in a face-sequential manner. Further, the receiving layer 15 may be provided between the base material 21 and the shielding layer 14.
Further, the dye layer 22 and the protective layer 16 may be provided in the face-sequential order with the stealth ink layer 12 and the like.
Furthermore, the primer layer 23 and the peeling layer 24 may be provided between arbitrary layers.
Further, a back surface layer 25 may be provided on the surface opposite to the side on which the stealth ink layer or the like is formed.
The layers constituting the thermal transfer sheet will be described below.

(Base material)
The base material has heat resistance that can withstand the heat energy (for example, the heat of the thermal head) when transferring the stealth ink layer to the transfer target of the laminate, and the mechanical strength that can support the stealth ink layer. Any solvent having solvent resistance or solvent resistance can be used without particular limitation. For example, various plastic films or sheets of polyester such as polyethylene terephthalate, polycarbonate, polyimide, polyetherimide, cellulose derivative, polyethylene, polypropylene, polystyrene, acrylic, polyvinyl chloride, polyvinylidene chloride, nylon, polyether ether ketone, etc. be able to.

The base material may be a copolymer resin or a mixture (including alloy) containing the above-mentioned resin as a main component, or a laminate composed of a plurality of layers. The base material may be a stretched film or an unstretched film, but for the purpose of improving strength, it is preferable to use a film stretched in a uniaxial direction or a biaxial direction.

The base material preferably has a thickness of 2.5 μm or more and 50 μm or less. By setting the thickness of the substrate within the above numerical range, it is possible to improve the transferability of the stealth ink layer and the like while maintaining the mechanical strength.

Corona discharge treatment, plasma treatment, ozone treatment, flame treatment, primer (also known as anchor coat, adhesion promoter, and easy adhesive) coating treatment, preheat treatment, dust removal treatment, vapor deposition treatment, alkali treatment, charging You may perform an easy-adhesion process, such as provision of a preventive layer. In addition, additives such as a filler, a plasticizer, a colorant, and an antistatic agent may be added to the base material, if necessary.

(Stealth ink layer)
The thermal transfer sheet comprises a stealth ink layer on a substrate. The materials contained in the stealth ink layer are as described above.

The stealth ink layer is a coating liquid prepared by dissolving or dispersing in a suitable solvent such as water or an organic solvent by adding one or more materials selected from the above-mentioned materials and various additives as necessary. It can be formed by preparing and coating it on a substrate or the like by a means such as a gravure printing method, a screen printing method, or a reverse coating method using a gravure plate, and drying.

(Shielding layer)
The thermal transfer sheet may include a shielding layer on the base material. The materials contained in the shielding layer are as described above.

The shielding layer is prepared by adding a single or a plurality of materials selected from the above-mentioned materials and various additives as necessary and dissolving or dispersing them in an appropriate solvent such as water or an organic solvent to prepare a coating liquid. Then, it can be formed on the stealth ink layer or the like by coating and drying by means such as a gravure printing method, a screen printing method or a reverse coating method using a gravure plate.
Further, the coating amount during drying is preferably 0.2 μm or more and 15 μm or less, more preferably 0.5 μm or more and 10 μm or less.

(Receptive layer)
The thermal transfer sheet may include a receiving layer between the base material and the shielding layer. Further, the thermal transfer sheet is not limited to this, and may have a receiving layer so as to be in a frame sequential manner with the shielding layer and the like. The materials contained in the receiving layer are as described above.

The receiving layer is prepared by adding a single or plural materials selected from the above-mentioned materials and various additives as necessary, and dissolving or dispersing them in an appropriate solvent such as water or an organic solvent to prepare a coating liquid. Then, it can be formed by coating and drying it on the shielding layer or the like by means such as a gravure printing method, a screen printing method, or a reverse coating method using a gravure plate.

(Dye layer)
The thermal transfer sheet may be provided with a dye layer so as to be surface-sequential with the stealth ink layer or the like.

The dye layer preferably comprises a sublimation type dye, for example, diarylmethane dyes, triarylmethane dyes, thiazole dyes, merocyanine dyes, pyrazolone dyes, methine dyes, indoaniline dyes, acetophenone azomethine, Azomethine dyes such as pyrazoloazomethine, imidazoleazomethine, imidazoazomethine, and pyridoneazomethine, xanthene dyes, oxazine dyes, cyanostyrene dyes such as dicyanostyrene and tricyanostyrene, thiazine dyes, azine dyes, acridine dyes Dyes, benzene azo dyes, pyridone azo, thiophene azo, isothiazole azo, pyrrole azo, pyrazole azo, azo dyes such as imidazole azo, thiadiazole azo, triazole azo, disazo, spiropyran dyes, indinospiropyran dyes, fluorane dyes, Rhodamine lactam dyes, naphthoquinone dyes, anthraquinone dyes, quinophthalone dyes, and the like can be mentioned, and more specifically, MSRedG (manufactured by Mitsui Toatsu Chemicals, Inc.), Macrolex Red Violet R (manufactured by Bayer), and CeresRed 7B ( Bayer), red dyes such as Samaron Red F3BS (manufactured by Mitsubishi Chemical), Holon Brilliant Yellow 6GL (manufactured by Clariant), PTY-52 (manufactured by Mitsubishi Kasei), Macrolex Yellow 6G (manufactured by Bayer), etc. Yellow dye, Kayaset Blue 714 (manufactured by Nippon Kayaku Co., Ltd.), Waxoline Blue AP-FW (manufactured by ICI), Holon Brilliant Blue SR (manufactured by Sando Co.), MS Blue 100 (manufactured by Mitsui Toatsu Kagaku Co., Ltd.). , C.I. I. Blue dyes such as Solvent Blue 22 can be used.

The content of the dye in the dye layer is preferably in the range of 50 parts by mass or more and 350 parts by mass with respect to 100 parts by mass of the total solid content of the binder resin described later, and in the range of 80 parts by mass or more and 300 parts by mass. It is more preferable that When the content of the sublimable dye is less than the above range, the print density tends to decrease, and when it exceeds the above range, the preservability and the like tend to decrease.

The dye layer preferably contains a binder resin for supporting the above dye, for example, a cellulose resin, a vinyl resin, an acrylic resin, a polyurethane resin, a polyamide resin, a polyester resin, a polyvinyl butyral resin. , Polyvinyl acetal resin, and the like.

The content of the binder resin in the dye layer is preferably 20% by mass or more and 80% by mass or less.

The dye layer is prepared by adding one or more materials selected from the above-mentioned materials and various additives as necessary, and dissolving or dispersing them in an appropriate solvent such as water or an organic solvent to prepare a coating liquid. Then, it can be formed by coating and drying it on a substrate or the like by means such as a gravure printing method, a screen printing method, or a reverse coating method using a gravure plate.

The thermal transfer sheet may be provided with a protective layer so as to be surface-sequential with the stealth ink layer and the like. The materials and the like contained in the protective layer are as described above.

(Protective layer)
The protective layer is prepared by adding a single or plural materials selected from the above-mentioned materials and various additives as necessary, and dissolving or dispersing them in an appropriate solvent such as water or an organic solvent to prepare a coating liquid. Then, it can be formed by coating and drying it on the hiding layer or the like by a means such as a gravure printing method, a screen printing method, or a reverse coating method using a gravure plate. Further, when the protective layer contains an actinic ray curable resin, it is preferable to apply the actinic ray after coating with the coating liquid.

(Primer layer)
The thermal transfer sheet may be provided between any layers such as between the base material and the dye layer, or may be provided on the outermost surface of the color material layer or the like. The materials and the like contained in the primer layer are as described above.

The primer layer is prepared by adding a single or plural materials selected from the above-mentioned materials and various additives as necessary, and dissolving or dispersing them in an appropriate solvent such as water or an organic solvent to prepare a coating liquid. Then, it can be formed by coating and drying it on a substrate or the like by means such as a gravure printing method, a screen printing method, or a reverse coating method using a gravure plate.

(Peeling layer)
The thermal transfer sheet may include a release layer between the substrate and any layer. By providing the heat-melt transfer sheet with the release layer, the releasability from the base material of each layer transferred from the heat transfer sheet to the transfer target can be improved. Further, the peeling layer is positioned on the outermost surface layer of the transfer target after the transfer.

The release layer is prepared by adding one or more materials selected from the above-mentioned materials and various additives as necessary, and dissolving or dispersing them in an appropriate solvent such as water or an organic solvent to prepare a coating solution. Then, it can be formed by coating and drying it on the hiding layer by a means such as a gravure printing method, a screen printing method, or a reverse coating method using a gravure plate.

(Back layer)
The thermal transfer sheet may include a back surface layer on the surface (back surface) opposite to the surface on which the stealth ink layer or the like is formed. The back surface layer is a layer provided as desired in order to prevent adverse effects such as heat fusion, sticking, and wrinkles when heated by a thermal head or the like from the back surface side of the substrate during thermal transfer.

There is no limitation on the material of the back layer, for example, a cellulose resin such as ethyl cellulose, methyl cellulose, cellulose acetate, cellulose acetate butyrate, nitrocellulose, cellulose acetate butyrate, cellulose acetate propionate, polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral. , Polyvinyl acetal, polyvinyl-based resin such as polyvinylpyrrolidone, polymethyl methacrylate, polyethyl acrylate, polyacrylamide, acrylic resin such as acrylonitrile-styrene copolymer, polyamide resin, polyamideimide resin, coumarone indene resin, polyester Examples thereof include series resins, polyurethane resins, natural or synthetic resins such as silicone-modified or fluorine-modified urethane, or a mixture thereof.

The back layer preferably contains a slip agent, and examples thereof include metal soap, wax, silicone oil, fatty acid ester, filler, talc, and surfactant.

The back layer is prepared by adding one or more materials selected from the above-mentioned materials and various additives as necessary, and dissolving or dispersing them in an appropriate solvent such as water or an organic solvent to prepare a coating liquid. Then, it can be formed by coating and drying it on a substrate by means such as a gravure printing method, a screen printing method, or a reverse coating method using a gravure plate.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

(Example 1)
<Preparation of thermal transfer sheet>
A 4.5 μm-thick PET film was used as a base material, and a back layer coating solution having the following composition was applied thereon so that the coating amount when dried was 1.0 μm, and the back layer was dried. Was formed.

(Coating liquid for back layer)
-Polyvinyl butyral resin 1.8 parts by mass (Sekisui Chemical Co., Ltd., S-REC BX-1)
5.5 parts by mass of polyisocyanate (manufactured by DIC Corporation, Burnock D750)
・Phosphate ester type surfactant 1.6 parts by mass (Daiichi Kogyo Seiyaku Co., Ltd., Prysurf A208N)
・Talc 0.35 parts by mass (manufactured by Nippon Talc Industry Co., Ltd., Microace P-3)
-Toluene 18.5 parts by mass-Methyl ethyl ketone 18.5 parts by mass

On a part of the surface opposite to the side provided with the back layer of the base material, a stealth ink layer coating solution having the following composition is applied so that the coating amount when dried is 0.4 μm, It was dried to form a stealth ink layer.

(Stealth ink layer coating liquid)
-Acrylic resin 8.5 parts by mass (Mitsubishi Rayon Co., Ltd., Diinal BR-87)
-Diimonium salt 1.5 parts by mass (CIR-RL manufactured by Nippon Carlit Co., Ltd.)
-Toluene 45 parts by mass-Methyl ethyl ketone 45 parts by mass

On a part of the surface opposite to the side provided with the back layer of the base material, a receiving layer coating solution having the following composition is dried so as to be surface-sequential with the stealth ink layer formed as described above. The coating amount was 0.8 μm, and the coating layer was dried to form a receiving layer.

(Receptor layer coating liquid)
-Vinyl chloride-vinyl acetate copolymer resin 15.8 parts by mass (Nisshin Chemical Industry Co., Ltd., Solvene CNL)
・Vinyl chloride-vinyl acetate copolymer resin 1.0 part by mass (Nisshin Chemical Industry Co., Ltd., Solvein C)
-Organic modified silicone oil 1.2 parts by mass (X-22-3000T, manufactured by Shin-Etsu Chemical Co., Ltd.)
-Organic modified silicone oil 1.2 parts by mass (Shin-Etsu Chemical Co., Ltd., X-24-510)
-Organic modified silicone oil 0.8 parts by mass (KF-352A, manufactured by Shin-Etsu Chemical Co., Ltd.)
・Methyl ethyl ketone 40 parts by mass ・Toluene 40 parts by mass

On the receptor layer formed as described above, a primer layer coating solution having the following composition was applied so that the coating amount when dried was 0.1 μm, and the primer layer A was formed. Let

(Coating liquid for primer layer)
-Alumina sol 2.5 parts by mass (Nissan Chemical Co., Ltd., alumina sol 200)
・Polyvinylpyrrolidone resin 2.5 parts by mass (ISP Japan Co., Ltd., PVP K-60)
-Water 47.5 parts by mass-Isopropyl alcohol 47.5 parts by mass

On the primer layer formed as described above, the shielding layer coating liquid 1 having the following composition was applied so that the coating amount when dried was 1.4 μm, and dried to form a shielding layer. Let

(Coating liquid for shield layer 1)
Acrylic resin 8 parts by mass Vinyl chloride-vinyl acetate copolymer 2 parts by mass Titanium oxide 30 parts by mass Toluene 30 parts by mass Methyl ethyl ketone 30 parts by mass

The primer layer coating liquid having the above composition is applied so that the coating amount is 0.1 μm and the coating liquid is dried so as to be surface-sequential to the receiving layer formed as described above. The primer layer B was formed. On the primer layer B, a yellow dye layer coating liquid (Y), a magenta dye layer coating liquid (M), and a cyan dye layer coating liquid (C) having the following compositions were applied by a gravure printing machine. Each layer was coated and dried so that the coating amount when dried was 0.7 μm, and the dye layer was formed in this order by repeating frame-sequentially.

(Yellow dye layer coating liquid (Y))
Solvent Yellow 93 2 parts by mass Disperse Yellow 201 5 parts by mass Polyvinyl acetal resin 5 parts by mass (KS-5, manufactured by Sekisui Chemical Co., Ltd.)
・Toluene 50 parts by mass ・Methyl ethyl ketone 50 parts by mass

(Coating liquid for magenta dye layer (M))
Disperse Red 60 3 parts by mass Disperse Violet 26 4 parts by mass Polyvinyl acetal resin 5 parts by mass (Sekisui Chemical Co., Ltd., KS-5)
・Toluene 50 parts by mass ・Methyl ethyl ketone 50 parts by mass

(Coating liquid for cyan dye layer (C)
Solvent Blue 63 4 parts by mass Disperse Blue 354 4 parts by mass Polyvinyl acetal resin 5 parts by mass (Sekisui Chemical Co., Ltd., KS-5)
・Toluene 50 parts by mass ・Methyl ethyl ketone 50 parts by mass

The release layer coating liquid having the following composition was applied so that the primer layer formed as described above was surface-sequential so that the coating amount during drying was 0.8 μm, and the coating liquid was dried. A release layer was formed. A primer layer coating solution having the above composition was applied on the release layer so that the coating amount when dried was 0.1 μm, and dried to form a primer layer C. The primer layer C was coated with a coating solution for protective layer having the following composition so that the coating amount when dried was 0.8 μm, and dried to form a protective layer, as shown in FIG. A thermal transfer sheet was obtained.

(Coating liquid for release layer)
・Acrylic resin 20 parts by mass (Mitsubishi Rayon Co., Ltd., Diinal BR-87)
・Methyl ethyl ketone 40 parts by mass ・Toluene 40 parts by mass

(Coating liquid for protective layer)
・Polyester resin 24 parts by mass (Toyobo Co., Ltd., Byron 700)
・UV absorber 6 parts by mass ・Toluene 35 parts by mass ・Methyl ethyl ketone 35 parts by mass

<Formation of laminated body>
A genuine paper of a sublimation type transfer printer (DS-40 manufactured by DNP Photolucio Co., Ltd.) was prepared as a transferred material.

The stealth ink layer included in the thermal transfer sheet prepared as described above was heat-melt transferred onto the transfer target so as to form a code pattern, using the following test printer. The thickness of the stealth ink layer on the transferred material was 0.4 μm.
(Test printer)
Thermal head: KEE-57-12GAN2-STA (manufactured by Kyocera Corp.)
Heating element average resistance value: 3303 (Ω)
Printing density in main scanning direction: 300 dpi
Sub scanning direction print density: 300 dpi
Printing voltage: 18 (V)
1 line cycle: 1.5 (msec.)
Printing start temperature: 35 (℃)
Pulse duty ratio: 85%

The shielding layer, the primer layer A, and the receiving layer included in the thermal transfer sheet were simultaneously heat-melt transferred onto the transferred material and the stealth ink layer using the test printer. The shielding layer had a thickness of 1.4 μm, the primer layer A had a thickness of 0.1 μm, and the receiving layer had a thickness of 0.8 μm.

The test printer was used to transfer the dye from the dye layer provided in the thermal transfer sheet onto the receiving layer to form an image.

The protective layer, the primer layer C, and the release layer B provided on the thermal transfer sheet were heat-melt transferred onto the image-receiving layer to obtain a laminate. The protective layer had a thickness of 0.8 μm, the primer layer C had a thickness of 0.1 μm, and the release layer A had a thickness of 0.8 μm.
The total thickness of the shielding layer, the primer layer A, the receiving layer, the protective layer, the primer layer C, and the release layer A (the thickness of the concealing layer) was 4.0 μm, which was 10 times the thickness of the stealth ink layer. there were.

(Example 2)
Other than changing the coating amount of the coating liquid 1 for the shielding layer, the coating liquid for the primer layer and the coating liquid for the receiving layer so that the thickness of the hiding layer is 5 times the thickness of the stealth ink layer. A laminate was prepared in the same manner as in Example 1.

(Example 3)
A laminate was prepared in the same manner as in Example 1 except that the composition of the shielding layer coating liquid 1 was changed to the following, so that the thickness of the concealing layer was 10 times the thickness of the stealth ink layer.
(Coating liquid 2 for shielding layer)
Acrylic resin 8 parts by mass Vinyl chloride-vinyl acetate copolymer 2 parts by mass Sublimation dye (same color as the stealth ink layer) 0.2 parts by mass Toluene 45 parts by mass Methyl ethyl ketone 45 parts by mass

(Example 4)
Other than changing the coating amount of the coating liquid 2 for the shielding layer, the coating liquid for the primer layer and the coating liquid for the receiving layer so that the thickness of the hiding layer is 5 times the thickness of the stealth ink layer. A laminate was prepared in the same manner as in Example 3.

(Comparative Example 1)
Other than changing the coating amount of the coating liquid 1 for the shielding layer, the coating liquid for the primer layer, and the coating liquid for the receiving layer so that the thickness of the hiding layer is 3 times the thickness of the stealth ink layer. A laminate was prepared in the same manner as in Example 1.

(Comparative example 2)
Other than changing the coating amount of the coating liquid 2 for the shielding layer, the coating liquid for the primer layer and the coating liquid for the receiving layer so that the thickness of the concealing layer is 3 times the thickness of the stealth ink layer. A laminate was prepared in the same manner as in Example 2.

<Visual recognition test>
The laminates produced in Examples and Comparative Examples were visually observed to evaluate whether the position of the stealth ink layer and the code pattern formed by the stealth ink layer can be recognized according to the following evaluation criteria. The evaluation results are shown in Table 1.
(Evaluation criteria)
A: Even if a person who knew the position of the stealth ink layer in advance saw it, the position and shape could not be recognized.
B: When a person who knew the position of the stealth ink layer looked in advance, the position and shape could be recognized, but when an unknown person saw it, the position and shape could not be recognized.
C: Even if a person who did not know the position and shape of the stealth ink layer in advance saw it, the position and shape could be recognized.

10: laminated body 11: transferred material 12: stealth ink layer 13: concealing layer 14: shielding layer 15: receiving layer 16: protective layer 20: thermal transfer sheet 21: substrate 22: dye layer 23: primer layer 24: release layer 25: Back layer

Claims (7)

A base material, and a stealth ink layer and a first transfer layer, which are provided on the base material in a peelable manner in a surface-sequential manner and include an invisible light absorbing material,
The first transfer layer comprises a receptive layer for receiving a heat transferable color material, and a shielding layer provided on the receptive layer,
The thermal transfer sheet, wherein the thickness of the first transfer layer is 4 times or more the thickness of the stealth ink layer. A base material, and a stealth ink layer comprising an invisible light absorbing material, a first transfer layer and a second transfer layer, which are provided on the base material in a surface-sequential manner in a peelable manner,
The first transfer layer comprises a receptive layer for receiving a heat transferable color material, and a shielding layer provided on the receptive layer,
The second transfer layer comprises a protective layer,
The thermal transfer sheet, wherein the sum of the thicknesses of the first transfer layer and the second transfer layer is 4 times or more the thickness of the stealth ink layer. The thermal transfer sheet according to claim 1, further comprising a dye layer so as to be in a frame sequential manner with the first transfer layer. A step of preparing a transfer target,
A step of transferring the stealth ink layer from the thermal transfer sheet according to any one of claims 1 to 3 on the transfer target;
The step of transferring the first transfer layer from the thermal transfer sheet according to any one of claims 1 to 3 onto the transfer object and the stealth ink layer. And a method for manufacturing a laminate. The method according to claim 4, further comprising forming an image on the transferred receiving layer using the thermal transfer sheet according to claim 3. The method of claim 5, further comprising the step of transferring the second transfer layer from the thermal transfer sheet of claim 2 onto the imaged receiving layer. The method according to any one of claims 4 to 6, wherein the transfer of the stealth ink layer is performed using a gradation printing method.

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