JP7596895B2 - Thermal transfer image receiving sheet, method for producing printed matter, and printed matter - Google Patents

Description

This disclosure relates to a thermal transfer image receiving sheet, a method for producing a printed matter, and a printed matter.

A variety of image forming methods are known in the past. Among them, the dye-sublimation thermal transfer method allows for free adjustment of density gradation, has excellent reproducibility of intermediate colors and gradations, and is capable of forming high-quality images comparable to silver halide photography.

In the dye-sublimation thermal transfer method, a thermal transfer sheet having a sublimation transfer color material layer containing a sublimation dye and a thermal transfer image receiving sheet having a receiving layer are usually used. For example, the thermal transfer sheet and the thermal transfer image receiving sheet are superimposed, and then the thermal transfer sheet is heated by a heat generating member such as a thermal head of the printer, thereby transferring the sublimation dye in the sublimation transfer color material layer to the receiving layer to form an image, thereby obtaining a printed matter (see, for example, Patent Document 1).

Conventional thermal transfer image receiving sheets do not have sufficient transportability when printed using, for example, a grip roller type printer. Therefore, in order to improve transportability, a thermal transfer image receiving sheet with a grip layer on the back surface has been proposed (see, for example, Patent Document 2).

JP 2001-39043 A Japanese Patent Application Publication No. 11-115328

If the transportability of thermal transfer image receiving sheets during printing could be improved, high-quality images could be achieved. However, with conventional thermal transfer image receiving sheets, depending on the printer used, the transportability is insufficient, and double feeding can occur, for example. In addition, transport scratches can be caused on the back of the printed matter by the transport rollers, reducing the quality of the printed matter.

The problem to be solved by this disclosure is to provide a thermal transfer image receiving sheet that is excellent in transportability during printing and suppresses the occurrence of transport scratches on the back side, and also to provide a method for producing a printed matter using the thermal transfer image receiving sheet, and a printed matter.

The thermal transfer image receiving sheet of the present disclosure is a thermal transfer image receiving sheet that includes a back layer, a back primer layer, a substrate, and a receiving layer in this order, the back primer layer contains a pigment and a resin material containing a urethane resin component, the mass ratio of the pigment content to the resin material content in the back primer layer (pigment content/resin material content) is 1.00 or more and 3.00 or less, and the thickness of the back primer layer is 0.20 μm or more and 0.90 μm or less.

The method for producing a print product according to the present disclosure includes (1) a step of preparing the thermal transfer image receiving sheet, and (2) a step of forming an image on a receiving layer provided in the thermal transfer image receiving sheet.

The printed matter of the present disclosure comprises the thermal transfer image receiving sheet and an image formed on a receiving layer of the thermal transfer image receiving sheet.

According to the present disclosure, it is possible to provide a thermal transfer image receiving sheet that has excellent transportability during printing and suppresses the occurrence of transport scratches on the back side, and also to provide a method for producing a printed matter using the thermal transfer image receiving sheet, and a printed matter.

FIG. 1 is a schematic cross-sectional view showing one embodiment of the thermal transfer image-receiving sheet of the present disclosure. FIG. 2 is a schematic cross-sectional view showing one embodiment of the thermal transfer image-receiving sheet of the present disclosure. FIG. 3 is a schematic cross-sectional view showing one embodiment of a print material of the present disclosure. FIG. 4 is a schematic cross-sectional view showing one embodiment of a print material of the present disclosure.

Embodiments of the present disclosure will be described below with reference to the drawings. Note that the present disclosure can be implemented in many different forms and should not be interpreted as being limited to the description of the embodiments exemplified below.

In order to clarify the explanation, the drawings may show the width, thickness, angle, shape, etc. of each part in a schematic manner compared to the actual form. However, the drawings are merely examples and do not limit the interpretation of the present disclosure. In this specification and each figure, elements similar to those explained with reference to the previous figures may be given the same reference numerals and detailed explanations may be omitted as appropriate. For convenience of explanation, the terms "upper" and "lower" are used in the explanation, but the up-down direction may be reversed. The same applies to the left-right direction.

[Thermal transfer image receiving sheet]
The thermal transfer image receiving sheet of the present disclosure includes a back layer, a back primer layer, a substrate, and a receiving layer in this order in the thickness direction. The thermal transfer image receiving sheet 1 of one embodiment shown in Fig. 1 includes a back layer 14, a back primer layer 12, a substrate 10, and a receiving layer 20 in this order in the thickness direction. The thermal transfer image receiving sheet 1 of one embodiment shown in Fig. 2 includes a back layer 14, a back primer layer 12, a substrate 10, a heat insulating layer 16, a primer layer 18, and a receiving layer 20 in this order in the thickness direction. An adhesive layer (not shown) may be provided between the substrate 10 and the heat insulating layer 16.
Hereinafter, each layer of the thermal transfer image receiving sheet of the present disclosure will be described in detail.

<Substrate>
Substrates include, for example, film and paper substrates.

Examples of the film include films made of resin materials (hereinafter also referred to as "resin films"). Examples of the resin materials include polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyolefins such as polyethylene, polypropylene, and polymethylpentene; vinyl resins such as polyvinyl chloride, polyvinyl acetate, and vinyl chloride-vinyl acetate copolymers; (meth)acrylic resins such as polyacrylate, polymethacrylate, and polymethyl methacrylate; styrene resins such as polystyrene; polycarbonate; and ionomer resins.

In this disclosure, "(meth)acrylic" includes both "acrylic" and "methacrylic." Also, "(meth)acrylate" includes both "acrylate" and "methacrylate."

Examples of paper substrates include condenser paper, glassine paper, parchment paper, synthetic paper, fine paper, art paper, coated paper, uncoated paper, cast-coated paper, wallpaper, cellulose fiber paper, synthetic resin-imparted paper, backing paper, and impregnated paper. Examples of impregnated paper include synthetic resin-impregnated paper, emulsion-impregnated paper, and synthetic rubber latex-impregnated paper.

When the substrate is a resin film, the resin film may be a stretched film or an unstretched film. From the viewpoint of mechanical strength, it is preferable to use a uniaxially or biaxially stretched film as the substrate.

The substrate is preferably a resin film, more preferably a film made of polyester (polyester film) and a film made of polyolefin (polyolefin film), and even more preferably a polyethylene terephthalate film and a polypropylene film. The resin film may be a stretched film.

A laminate (laminated substrate) of the above-mentioned resin film and paper substrate may be used as the substrate. The laminate can be produced, for example, by using the dry lamination method, the wet lamination method, and the extrusion method. For example, a laminate of a polyester film or a polyolefin film and a paper substrate is preferred, and a laminate of a polyethylene terephthalate film or a polypropylene film and a paper substrate is more preferred. The resin film may be a stretched film.

From the viewpoint of mechanical strength, the thickness of the substrate is preferably 20 μm or more and 500 μm or less, more preferably 50 μm or more and 400 μm or less, and even more preferably 100 μm or more and 300 μm or less.

<Back layer>
The thermal transfer image receiving sheet of the present disclosure includes a backing layer on the surface of the substrate opposite to the receiving layer.
By providing the back surface layer, for example, the transportability during printing of the thermal transfer image receiving sheet, specifically, the transportability during printing using a grip roller type printer, etc. By providing the back surface layer, for example, the writability on the back side of the thermal transfer image receiving sheet can be improved.

In one embodiment, the back surface layer contains a resin material. Examples of the resin material include polyvinyl acetal resins such as polyvinyl butyral resin and polyvinyl acetoacetal resin; vinyl resins such as polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer and polyvinyl alcohol resin; polyolefin, (meth)acrylic resin, styrene resin, polyester, polyamide, polyimide, polycarbonate, and cellulose resin. The back surface layer can contain one or more types of resin materials.

The resin material may be a crosslinked product of a resin having a functional group such as a hydroxyl group with a crosslinking agent capable of reacting with the functional group. Examples of the crosslinking agent include metal chelate-based crosslinking agents such as titanium chelate compounds and zirconium chelate compounds, isocyanate-based crosslinking agents, epoxy-based crosslinking agents, oxazoline-based crosslinking agents, and melamine-based crosslinking agents. One or more types of crosslinking agents may be used. Among these, metal chelate-based crosslinking agents are preferred. For example, a crosslinked product of a polyvinyl acetal resin or a polyvinyl alcohol resin with a metal chelate-based crosslinking agent is preferred.

The amount of crosslinking agent used is preferably 0.1 parts by mass or more and 20 parts by mass or less, more preferably 0.5 parts by mass or more and 10 parts by mass or less, and even more preferably 1 part by mass or more and 5 parts by mass or less, per 100 parts by mass of the resin having a functional group such as a hydroxyl group.

The back layer may contain additives. Examples of additives include plasticizers, color inhibitors, surfactants, fluorescent brighteners, matting agents, deodorants, flame retardants, antistatic agents, friction reducers, slip agents, dispersants, UV absorbers, antioxidants, weather stabilizers, fillers, and colorants such as pigments and dyes. The back layer may contain one or more additives.

The thickness of the back layer is preferably 0.05 μm or more and 2.00 μm or less, more preferably 0.13 μm or more and 1.30 μm or less. The coating amount of the back layer in a dry state is preferably 0.10 g/m ² or more and 5.0 g/m ² or less, more preferably 0.10 g/m ² or more and 3.0 g/m ² or less, and even more preferably 0.20 g/m ² or more and 2.0 g/m ² or less. By such an embodiment, for example, the transportability and abrasion resistance during printing of the thermal transfer image receiving sheet can be further improved.

The back surface layer can be formed, for example, by dispersing or dissolving the above-mentioned materials in water or a suitable organic solvent to prepare a coating liquid, applying the coating liquid onto the back surface primer layer by a known coating method to form a coating film, and drying the coating film. Examples of coating methods include roll coating, reverse roll coating, gravure coating, reverse gravure coating, bar coating, and rod coating.

<Rear primer layer>
The thermal transfer image receiving sheet of the present disclosure includes a specific back primer layer between the substrate and the back layer, which is described below. The back primer layer is provided for the purpose of improving the adhesion between the substrate and the back layer and imparting the concealment property of the base, for example.

When using a conventional thermal transfer image receiving sheet, depending on the type of thermal transfer printer (e.g., a grip roller type printer), double feeding may occur during printing. In the present disclosure, a specific back primer layer is provided between the substrate and the back layer, so that double feeding during printing is suppressed and transportability is excellent.

Furthermore, when a conventional thermal transfer image receiving sheet is used, depending on the type of thermal transfer printer, the back surface of the printed matter may be scratched by the transport rollers, resulting in a decrease in the quality of the printed matter. This is thought to be because the back surface layer of the thermal transfer image receiving sheet is prone to peeling and scratches. In the present disclosure, a specific back surface primer layer is provided between the substrate and the back surface layer, which prevents the back surface layer from peeling off and thus prevents scratches from being caused during transport. Therefore, according to the present disclosure, high-quality printed matter can be achieved.

The back surface primer layer contains a resin material containing a urethane resin component.
The urethane resin component is, for example, at least one selected from a urethane resin and a crosslinked product of the urethane resin with a crosslinking agent for urethane resin.

Urethane resins are polymers of polyols and polyisocyanates, and examples of such resins include polyester-based urethane resins, polyether-based urethane resins, polylactone-based urethane resins, polycarbonate-based urethane resins, polyester-polycarbonate-based urethane resins, castor oil-based urethane resins, polyolefin-based urethane resins, polybutadiene-based urethane resins, polyisoprene-based urethane resins, and poly(meth)acrylic-based urethane resins.

The polyol is a compound having two or more hydroxyl groups. The number of hydroxyl groups in the polyol is preferably 2 or more and 3 or less. Examples of polyols include polyester polyols, polyether polyols, polylactone polyols, polycarbonate polyols, polyester polycarbonate polyols, castor oil polyols, polyolefin polyols, polybutadiene polyols, polyisoprene polyols, and poly(meth)acrylic polyols. One or more types of polyols can be used.

The polyisocyanate is a compound having two or more isocyanate groups. The number of isocyanate groups in the polyisocyanate is preferably 2 or more and 9 or less. Examples of polyisocyanates include aromatic polyisocyanates such as phenylene diisocyanate, biphenylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, tolylene diisocyanate, xylylene diisocyanate, naphthalene diisocyanate, and diphenyl ether diisocyanate; alicyclic polyisocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate, and dicyclohexylmethane diisocyanate; aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; and polyol adducts of these compounds, biuret bodies of these compounds, and trimers having an isocyanurate ring of these compounds. Polyisocyanates can be used alone or in combination.

Examples of the polyol adducts include trimethylolpropane adducts such as trimethylolpropane/tolylene diisocyanate trimer adducts and trimethylolpropane/hexamethylene diisocyanate trimer adducts. Examples of the trimers include isocyanurates of hexamethylene diisocyanate.

The weight average molecular weight (Mw) of the urethane resin is preferably 1,000 or more and 200,000 or less, more preferably 10,000 or more and 100,000 or less. Mw is measured by gel permeation chromatography (GPC) and is expressed in terms of standard polystyrene.

The softening point of the urethane resin is preferably 50°C or higher, more preferably 55°C or higher and 140°C or lower, even more preferably 60°C or higher and 120°C or lower, and particularly preferably 80°C or higher and 100°C or lower. The softening point is measured in accordance with JIS K7196.

The glass transition temperature (Tg) of the urethane resin is preferably -50°C or higher and 10°C or lower, more preferably -40°C or higher and 5°C or lower, even more preferably -28°C or higher and 5°C or lower, and particularly preferably -20°C or higher and 5°C or lower. Tg is measured by differential scanning calorimetry (DSC) in accordance with JIS K7121.

As a crosslinking agent for urethane resin, an isocyanate-based crosslinking agent is preferable. Examples of the isocyanate-based crosslinking agent include the polyisocyanates described above as raw materials for urethane resin. One or more types of isocyanate-based crosslinking agents can be used. By using a combination of a urethane resin and a crosslinking agent in this way, for example, the adhesion between the substrate and the back layer can be further improved.

The amount of the crosslinking agent for urethane resin used is preferably 0.5 parts by mass or more and 30 parts by mass or less, more preferably 1 part by mass or more and 25 parts by mass or less, and even more preferably 5 parts by mass or more and 20 parts by mass or less, relative to 100 parts by mass of urethane resin. The urethane resin and the isocyanate-based crosslinking agent are preferably used in an amount such that the ratio (NCO/OH) of the number of isocyanate groups in the isocyanate-based crosslinking agent to the number of hydroxyl groups in the urethane resin is 0.3 to 3.5. This tends to improve the adhesion between the substrate and the back layer, for example.

The back primer layer can contain one or more urethane resin components.

The back primer layer may further contain a resin material other than the urethane resin component. Examples of such resin materials include polyolefin, (meth)acrylic resin, vinyl resin, polyvinyl acetal resin, styrene resin, polyester, polyamide, polyimide, polycarbonate, and cellulose resin.

In the back primer layer, the content of the urethane resin component in the resin material is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more.

The back primer layer contains a pigment.
Examples of pigments include metal oxides such as titanium dioxide, zinc oxide, cerium oxide, aluminum oxide, and finely powdered silica; metal pigments such as aluminum powder, gold powder, silver powder, copper powder, bronze powder, zinc powder, stainless steel powder, and nickel powder; titanium mica, calcium carbonate, barium sulfate, alumina white, talc, and kaolin; inorganic pigments such as pearl pigments; and organic pigments such as chromatic pigments. The back primer layer can contain one or more types of pigments.

In one embodiment, the back primer layer contains one or more white pigments as the pigment. Examples of white pigments include titanium dioxide, zinc oxide, finely powdered silica, calcium carbonate, barium sulfate, alumina white, and kaolin. In this manner, the concealment of the base can be further improved.

The back primer layer may contain additives. Examples of additives include plasticizers, color inhibitors, surfactants, fluorescent brighteners, matting agents, deodorants, flame retardants, antistatic agents, friction reducers, slip agents, dispersants, UV absorbers, antioxidants, weather stabilizers, and dyes. The back primer layer may contain one or more additives.

In one embodiment, the back primer layer contains one or more types of fluorescent brightener. Examples of the fluorescent brightener include thiophene-based fluorescent brighteners such as 2,5-bis(5-t-butyl-2-benzoxazolyl)thiophene and 2,5-bis(benzoxazol-2-yl)thiophene, coumarin-based fluorescent brighteners, stilbene-based fluorescent brighteners, naphthalene-based fluorescent brighteners, and benzimidazole-based fluorescent brighteners.

The mass ratio of the pigment content to the resin material content in the back primer layer (pigment content/resin material content, hereinafter also referred to as "PV ratio") is 1.00 or more and 3.00 or less, and preferably 1.30 or more and 2.50 or less. If the PV ratio exceeds 3.00, the back surface of the thermal transfer image receiving sheet is easily scratched during transportation during printing, the writability of the back surface tends to decrease, and double feeding of the thermal transfer image receiving sheet tends to occur. If the PV ratio is less than 1.00, when the back primer layer contains a white pigment such as titanium dioxide, the hiding power tends to decrease. If the PV ratio is within the above range, a thermal transfer image receiving sheet that is excellent in transportability during printing, suppression of scratches during transportation, back writability, and hiding power can be obtained.

The thickness of the back primer layer is 0.20 μm or more and 0.90 μm or less, and preferably 0.30 μm or more and 0.80 μm or less. If the thickness exceeds 0.90 μm, double feeding of the thermal transfer image receiving sheet tends to occur during transportation during printing. If the thickness is less than 0.20 μm, the back surface of the thermal transfer image receiving sheet is easily scratched during transportation during printing, and the writability of the back surface tends to decrease. Furthermore, if the back primer layer contains a white pigment such as titanium dioxide, the hiding power tends to decrease. If the thickness is within the above range, a thermal transfer image receiving sheet that is excellent in transportability during printing, suppression of transport scratches, back writability, and hiding power can be obtained.

The thickness of the back primer layer can be measured from a photograph of a cross section of the thermal transfer image receiving sheet in the thickness direction observed with a scanning electron microscope (SEM) or from a photograph observed with SEM energy dispersive X-ray spectroscopy (SEM-EDX). The same applies to the thicknesses of the other layers.

The back primer layer can be formed, for example, by dispersing or dissolving the above-mentioned materials in water or a suitable organic solvent to prepare a coating liquid, applying the coating liquid to a substrate by the known coating means described above to form a coating film, and then drying the coating film.

<Thermal insulation layer>
In one embodiment, the thermal transfer image receiving sheet of the present disclosure includes a heat insulating layer. The heat insulating layer is provided, for example, between the substrate and the receiving layer. The heat insulating layer has heat insulating properties that suppress the loss of heat applied during image formation by thermal transfer due to heat transfer to the substrate or the like.

Examples of the heat insulating layer include a hollow particle-containing layer that contains hollow particles, and a porous film having fine voids inside. The heat insulating layer may have two or more hollow particle-containing layers, may have two or more porous films, or may have a hollow particle-containing layer and a porous film.

The hollow particle-containing layer contains hollow particles. By containing hollow particles, the hollow particle-containing layer has heat insulating properties that prevent the heat applied during image formation by thermal transfer from being lost through heat transfer to the substrate, etc., and also has cushioning properties.

The hollow particles may be organic hollow particles, inorganic hollow particles, or organic-inorganic composite hollow particles, but from the viewpoint of dispersibility in the resin material, organic hollow particles and organic-inorganic composite hollow particles are preferred.

The hollow particles may be expandable particles or non-expandable particles. The hollow particles may be particles consisting of a shell and a gas contained within the shell, or particles consisting of a shell and a liquid, such as liquid hydrocarbons, contained within the shell.

The organic hollow particles have a shell made of a resin material. Examples of resin materials include (meth)acrylonitrile resins such as (meth)acrylonitrile copolymers, styrene resins such as polystyrene and crosslinked styrene-(meth)acrylic resins, vinyl resins such as polyvinylidene chloride, (meth)acrylic resins such as polymethyl(meth)acrylate, phenolic resins, fluororesins, imide resins, and polycarbonates.

In one embodiment, the organic hollow particles can be produced by encapsulating a foaming agent such as butane gas in resin particles and heating to foam them. In one embodiment, the organic hollow particles can be produced by utilizing emulsion polymerization. Commercially available organic hollow particles may be used.

The organic-inorganic composite hollow particles include, for example, hollow particles in which the shell surface of an organic hollow particle is modified with an inorganic material such as an inorganic powder. The organic hollow particles include, for example, the organic hollow particles exemplified above. The inorganic material includes, for example, talc, calcium carbonate, silica, titania, and alumina. In one embodiment, the organic-inorganic composite hollow particles are hollow particles in which the surface of a polyacrylonitrile-based hollow particle such as an acrylonitrile-based copolymer is modified with talc. Commercially available organic-inorganic composite hollow particles may be used.

Examples of inorganic hollow particles include hollow silica particles, hollow glass particles, and hollow ceramic particles.

The average particle diameter of the hollow particles is preferably 0.1 μm to 30 μm, more preferably 0.5 μm to 30 μm, and even more preferably 1 μm to 25 μm. The average particle diameter of the hollow particles is measured by an electron microscope. Specifically, a cross-sectional image of the cross section of the hollow particle-containing layer is obtained by a scanning electron microscope, and the particle diameter is obtained as the average value of the major axis diameter and the minor axis diameter of each particle in the cross-sectional image, and the arithmetic average of the particle diameters of 100 particles is taken as the average particle diameter.
The hollow particle-containing layer can contain one or more types of hollow particles.

The hollow particle content in the hollow particle-containing layer is preferably 5% by mass or more and 70% by mass or less, more preferably 15% by mass or more and 60% by mass or less, and even more preferably 30% by mass or more and 55% by mass or less.

The hollow particle-containing layer contains a resin material.
Examples of resin materials include urethane resin, (meth)acrylic resin, polyester, urethane-modified polyester, polycarbonate, polyamide, styrene resin, vinyl resin, polyolefin, gelatin and its derivatives, polyvinyl alcohol, polyvinylpyrrolidone, pullulan, carboxymethyl cellulose, hydroxyethyl cellulose, dextran, dextrin, poly(meth)acrylic acid and its salts, agar, κ-carrageenan, λ-carrageenan, ι-carrageenan, casein, xanthan gum, locust bean gum, alginic acid, and gum arabic.
The hollow particle-containing layer can contain one or more types of resin materials.

The content of the resin material in the hollow particle-containing layer is preferably 30% by mass or more and 95% by mass or less, more preferably 40% by mass or more and 85% by mass or less, and even more preferably 45% by mass or more and 70% by mass or less.

The hollow particle-containing layer may contain additives. Examples of additives include plasticizers, coloring inhibitors, surfactants, fluorescent whitening agents, matting agents, deodorants, flame retardants, static electricity inhibitors, friction reducers, slip agents, dispersants, UV absorbers, antioxidants, weather stabilizers, fillers, and colorants such as pigments and dyes. The hollow particle-containing layer may contain one or more additives.

The thickness of the hollow particle-containing layer is preferably 5 μm or more and 100 μm or less, more preferably 12 μm or more and 80 μm or less, even more preferably 18 μm or more and 60 μm or less, and particularly preferably 20 μm or more and 50 μm or less.

The hollow particle-containing layer can be formed, for example, by dispersing or dissolving the above-mentioned materials in water or a suitable organic solvent to prepare a coating liquid, applying the coating liquid to a substrate or the like by the above-mentioned known coating means to form a coating film, and then drying the coating film.

Examples of resin materials constituting the porous film include polyolefins such as polyethylene and polypropylene; vinyl resins such as polyvinyl acetate, vinyl chloride-vinyl acetate copolymer and ethylene-vinyl acetate copolymer; polyesters such as polyethylene terephthalate and polybutylene terephthalate; styrene resins; and polyamides. The porous film can contain one or more types of resin materials.

The porous film can contain one or more of the above additives.

The thickness of the porous film is preferably 20 μm or more and 150 μm or less, more preferably 30 μm or more and 130 μm or less.

The porous film can be produced by a known method. For example, the porous film can be produced by forming a mixture of the above-mentioned resin material and incompatible organic or inorganic particles into a film and stretching it as necessary. For example, the porous film can be produced by forming a mixture of polypropylene and adding polyester or (meth)acrylic resin having a higher melting point than polypropylene into a film and stretching it as necessary. The polyester or (meth)acrylic resin acts as a nucleating agent to form fine voids. The porous film is not limited to the porous film produced by the above-mentioned method, and commercially available porous films may be used.

The porous film can be laminated onto the substrate, for example, via an adhesive layer. Also, multiple porous films can be laminated together via adhesive layers.

<Recipient layer>
The thermal transfer image receiving sheet of the present disclosure includes a receiving layer, which is a layer that receives a sublimation dye transferred from a sublimation transfer color material layer (dye layer) included in the thermal transfer sheet, and maintains the formed image.

In one embodiment, the receiving layer contains a resin material. The resin material is not limited as long as it is a resin that is easily dyed with a dye, and examples thereof include polyolefins; vinyl resins such as polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, and ethylene-vinyl acetate copolymer; polyvinyl acetal resins such as polyvinyl butyral resin and polyvinyl acetoacetal resin; styrene resin, (meth)acrylic resin, polyester, polyamide, polycarbonate, urethane resin, cellulose resin, and ionomer resin. The receiving layer can contain one or more types of resin materials.

The content of the resin material in the receiving layer is preferably 70% by mass or more and 99% by mass or less, more preferably 80% by mass or more and 98% by mass or less, and even more preferably 90% by mass or more and 97% by mass or less.

In one embodiment, the receiving layer contains a release agent. This can improve the releasability between the thermal transfer image receiving sheet and the thermal transfer sheet, for example. Examples of the release agent include solid waxes such as polyethylene wax, amide wax, and Teflon (registered trademark) powder; fluorine-based or phosphate ester-based surfactants; silicone oils, and silicone resins.

The silicone oil is preferably a modified silicone oil such as a reactive silicone oil or a cured silicone oil. The modified silicone oil is preferably an amino-modified silicone, an epoxy-modified silicone, an aralkyl-modified silicone, an epoxy-aralkyl-modified silicone, an alcohol-modified silicone, a vinyl-modified silicone, or a urethane-modified silicone, and examples of the modified silicone oil include amino-modified silicone, epoxy-modified silicone, aralkyl-modified silicone, and epoxy-aralkyl-modified silicone.
The receiving layer may contain one or more release agents.

The content of the release agent in the receiving layer is preferably 0.5% by mass or more and 20% by mass or less, and more preferably 0.5% by mass or more and 10% by mass or less. This makes it possible to improve the releasability between the thermal transfer image receiving sheet and the thermal transfer sheet, for example, while maintaining the transparency of the receiving layer.

The receiving layer may contain one or more of the above additives. For example, the receiving layer may contain a white pigment from the viewpoint of improving the whiteness of the receiving layer and further enhancing the clarity of the thermal transfer image.

The thickness of the receiving layer is preferably 0.5 μm or more and 20 μm or less, and more preferably 1 μm or more and 10 μm or less. This can, for example, further improve the density of the image formed on the receiving layer.

The receiving layer can be formed, for example, by dispersing or dissolving the above-mentioned materials in water or a suitable organic solvent to prepare a coating liquid, applying the coating liquid onto any layer by the known coating means described above to form a coating film, and then drying the coating film.

<Adhesive Layer>
In one embodiment, the thermal transfer image receiving sheet of the present disclosure has an adhesive layer between any layers (for example, between the substrate and the heat insulating layer, between each layer in the laminated substrate, and between each layer constituting the heat insulating layer having a multi-layer structure). This can improve the adhesion between the layers.

In one embodiment, the adhesive layer contains a resin material. Examples of the resin material include vinyl resins such as polyvinyl acetate, polyvinyl chloride, ethylene-vinyl acetate copolymer, and vinyl chloride-vinyl acetate copolymer, polyolefins, polyesters, (meth)acrylic resins, polyol resins, and urethane resins. The adhesive layer can contain one or more types of resin materials.

The adhesive layer may contain one or more of the above additives.
The thickness of the adhesive layer is, for example, not less than 0.5 μm and not more than 10 μm.

The adhesive layer can be formed, for example, by dispersing or dissolving the above-mentioned materials in water or a suitable organic solvent to prepare a coating liquid, applying the coating liquid onto any layer by the above-mentioned known coating means to form a coating film, and drying the coating film. In one embodiment, the adhesive layer can be formed by melt-extruding a resin composition containing the above-mentioned materials.

The adhesive layer can also be formed using a conventionally known adhesive. The adhesive may be a one-component curing type, a two-component curing type, or a non-curing type. The adhesive may be a solventless adhesive or a solvent-based adhesive. The adhesive layer may be formed, for example, by a non-solvent lamination method or a dry lamination method.

Examples of adhesives include two-component curing urethane adhesives, polyester polyurethane adhesives, polyether polyurethane adhesives, (meth)acrylic adhesives, polyester adhesives, polyether adhesives, polyamide adhesives, epoxy adhesives, rubber adhesives, polyolefin adhesives, acid-modified polyolefin adhesives, polyvinyl acetate adhesives, and polyvinyl chloride adhesives.

<Primer layer>
In one embodiment, the thermal transfer image receiving sheet of the present disclosure includes a primer layer between the substrate or the heat insulating layer and the receiving layer, which can improve the adhesion between these layers.

In one embodiment, the primer layer contains a resin material. Examples of the resin material include polyester, polyamide, polycarbonate, urethane resin, polyolefin, (meth)acrylic resin, styrene resin, vinyl resin (e.g., polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, and polyvinyl alcohol), polyvinyl acetal resin (e.g., polyvinyl butyral resin and polyvinyl acetoacetal resin), and cellulose resin. The primer layer can contain one or more types of resin materials.

For resin materials having active hydroxyl groups, the isocyanate cured product of the resin material can be used as a binder. Examples of isocyanate compounds that can be used in this case include the polyisocyanates described above as raw materials for urethane resins.

The primer layer may contain one or more of the above additives.
The thickness of the primer layer is, for example, not less than 0.1 μm and not more than 3 μm.

The primer layer can be formed, for example, by dispersing or dissolving the above-mentioned materials in water or a suitable organic solvent to prepare a coating liquid, applying the coating liquid to a substrate or a heat insulating layer, etc., by the known coating means described above to form a coating film, and then drying the coating film.

[Printed matter]
The print of the present disclosure is produced using the thermal transfer image receiving sheet, and includes a back layer, a back primer layer, a substrate, and a receiving layer on which an image is formed. The details of each layer are as described above.

The image formed on the receiving layer is not particularly limited and may be a letter, a pattern, a symbol, or a combination of these. For example, the image can be formed on the receiving layer by using a thermal transfer sheet for a conventionally known dye-sublimation type thermal transfer recording method or a melting type thermal transfer recording method.

<Protective Layer>
In one embodiment, the printed matter of the present disclosure includes a protective layer on a receiving layer on which an image is formed. The printed matter 2 of one embodiment shown in Fig. 3 includes a back layer 14, a back primer layer 12, a substrate 10, a receiving layer 20 on which an image (not shown) is formed, and a protective layer 22 in this order in the thickness direction. The printed matter 2 of one embodiment shown in Fig. 4 includes a back layer 14, a back primer layer 12, a substrate 10, a heat insulating layer 16, a primer layer 18, a receiving layer 20 on which an image (not shown) is formed, and a protective layer 22 in this order in the thickness direction.

In one embodiment, the protective layer contains a resin material. The resin material is not particularly limited as long as it is transparent. Examples of the resin material include (meth)acrylic resin, styrene resin, vinyl resin, polyolefin, polyester, polyamide, cellulose resin, cured products of thermosetting resins, and cured products of active energy ray curable resins. The protective layer can contain one or more types of resin materials.

Examples of thermosetting resins include epoxy resins, melamine resins, guanamine resins, urea resins, unsaturated polyesters, thermosetting urethane resins, thermosetting (meth)acrylic resins, and aminoalkyd resins.

An active energy ray curable resin is a resin that cures when irradiated with active energy rays. Examples of active energy rays include electromagnetic waves such as ultraviolet rays (UV), X-rays, and gamma rays; and charged particle rays such as electron beams (EB), alpha rays, and ion beams. Examples of active energy ray curable resins include polyfunctional (meth)acrylate monomers and polyfunctional (meth)acrylate oligomers.

The content of the resin material in the protective layer is preferably 50% by mass or more, and more preferably 50% by mass or more and 95% by mass or less, which can improve, for example, the scratch resistance and storage stability of the image formed on the receiving layer.
The protective layer may contain one or more of the above additives.

The thickness of the protective layer is preferably 0.1 μm or more and 10 μm or less, and more preferably 0.5 μm or more and 5 μm or less. This can improve, for example, the scratch resistance and storage stability of the image formed on the receiving layer.

[Method of manufacturing printed matter]
The method for producing a printed matter of the present disclosure includes (1) a step of preparing the thermal transfer image receiving sheet of the present disclosure, and (2) a step of forming an image on a receiving layer of the thermal transfer image receiving sheet (image forming step). In one embodiment, the method for producing a printed matter of the present disclosure includes (3) a step of forming a protective layer on the receiving layer on which the image has been formed (protective layer forming step).
The structure of the thermal transfer image receiving sheet has been described above, and therefore will not be described here.

Methods for forming an image include, for example, a method using a thermal transfer sheet for a conventionally known sublimation thermal transfer recording method or a melting thermal transfer recording method. In the sublimation thermal transfer recording method, a thermal transfer sheet having a sublimation transfer color material layer containing a sublimation dye is used to transfer the sublimation dye to a receiving layer, thereby forming an image. In the melting thermal transfer recording method, a thermal transfer sheet having a melting transfer color material layer is used to transfer the melting transfer color material layer onto a receiving layer, thereby forming an image. Images may also be formed by combining these methods.

The protective layer can be formed by a conventional method, for example, by transferring a protective layer from a protective layer transfer sheet having a protective layer onto a receiving layer on which an image is formed. The protective layer may be formed by laminating a film for forming a protective layer onto the receiving layer via an adhesive layer or the like. Details of the protective layer are as described above. The protective layer transfer sheet may be a thermal transfer sheet having a protective layer in surface sequence with the color material layer.

Specifically, the image is formed by overlapping the thermal transfer sheet and the thermal transfer image receiving sheet of the present disclosure and applying heat from the rear side of the thermal transfer sheet using a heat generating member such as a thermal head to transfer the sublimable dye contained in the sublimation transfer color material layer to the receiving layer, or by transferring the melt transfer color material layer onto the receiving layer.

Specifically, the protective layer is formed by superposing a thermal transfer image receiving sheet having an image formed on a receiving layer and the protective layer transfer sheet, and applying heat from the back side of the protective layer transfer sheet using a heat generating member such as a thermal head to transfer the protective layer onto the receiving layer.

The present disclosure relates to, for example, the following [1] to [9].
[1] A thermal transfer image receiving sheet comprising a back layer, a back primer layer, a substrate, and a receiving layer in this order, wherein the back primer layer contains a pigment and a resin material including a urethane resin component, the mass ratio of the pigment content to the resin material content in the back primer layer (pigment content/resin material content) is 1.00 or more and 3.00 or less, and the thickness of the back primer layer is 0.20 μm or more and 0.90 μm or less.
[2] The thermal transfer image receiving sheet according to the above [1], wherein the thickness of the back layer is from 0.05 μm to 2.00 μm.
[3] The thermal transfer image receiving sheet according to the above [1] or [2], wherein the urethane resin component is at least one selected from the group consisting of urethane resins and urethane resins crosslinked with an isocyanate-based crosslinking agent.
[4] The thermal transfer image-receiving sheet according to the above [3], wherein the urethane resin has a softening point of 80° C. or higher and 100° C. or lower.
[5] The thermal transfer image-receiving sheet according to the above [3] or [4], wherein the urethane resin has a glass transition temperature of −28° C. or more and 5° C. or less.
[6] A method for producing a printed matter, comprising: (1) a step of preparing a thermal transfer image receiving sheet according to any one of the above items [1] to [5]; and (2) a step of forming an image on a receiving layer provided in the thermal transfer image receiving sheet.
[7] (3) The method for producing a printed matter according to the above [6], further comprising a step of forming a protective layer on the receiving layer on which the image is formed.
[8] A printed matter comprising the thermal transfer image receiving sheet according to any one of [1] to [5] above and an image formed on a receiving layer of the thermal transfer image receiving sheet.
[9] The print according to the above [8], further comprising a protective layer on the receiving layer on which the image is formed.

The thermal transfer image receiving sheet etc. of the present disclosure will be described in more detail below based on examples, but the thermal transfer image receiving sheet etc. of the present disclosure is not limited to these examples. In the following description, "parts" means "parts by mass."

[Preparation of coating solution for back primer layer]
A coating solution (1) for a back surface primer layer having the following composition was prepared.
Urethane resin 10.7 parts (solid content 3.20 parts)
(Nippolan (registered trademark) 5253, solid content 30% by mass, Tosoh Corporation)
Titanium dioxide 6.40 parts (TCA-888, Tochem Products Co., Ltd.)
Fluorescent whitening agent 0.06 parts (2,5-bis(5'-t-butylbenzoxazolyl-2')thiophene, Doubletex OB, DOUBLE BOND CHEMICAL IND. CO., LTD.)
Polyisocyanate compound: 0.48 parts (Coronate (registered trademark) HX, isocyanurate of hexamethylene diisocyanate, Tosoh Corporation)
Methyl ethyl ketone 20.2 parts

Coating solutions (2) to (5) for the back primer layer were prepared in the same manner as coating solution (1) for the back primer layer, except that the solid content ratio of each component was changed as shown in Table 1.

[Example 1]
A polypropylene film having internal voids (microvoids) (product name: #35 SP-U, Mitsui Chemicals Tohcello Co., Ltd.) was laminated to one side of a coated paper (product name: NeostarGloss 180, Moorim P&P Co., Ltd.) using an adhesive layer coating liquid having the following composition (coating amount: 2.5 g/ ^m2 (after drying)) to obtain a polypropylene film/adhesive layer/coated paper.

Next, a 25 μm thick PET film (product name: Lumirror (registered trademark) T-60, Toray Industries, Inc.) was laminated to the other side of the coated paper using a coating liquid for the adhesive layer having the following composition (coating amount: 2.5 g/ ^m2 (after drying)), to obtain a polypropylene film/adhesive layer/coated paper/adhesive layer/PET film.

Next, a primer layer coating liquid having the following composition was applied to the surface of the polypropylene film and dried to form a primer layer having a thickness of 1.5 μm. A receiving layer coating liquid having the following composition was applied to the primer layer and dried to form a receiving layer having a thickness of 4 μm. The above back primer layer coating liquid (1) was applied to the surface of the PET film and dried at 100°C for 1 minute to form a back primer layer having a thickness of 0.40 μm. A back layer coating liquid having the following composition was applied to the back primer layer and dried at 100°C for 1 minute to form a back layer having a thickness of 0.19 μm.

In this way, a thermal transfer image receiving sheet was obtained. The thermal transfer image receiving sheet has the following layer structure: receiving layer/primer layer/polypropylene film/adhesive layer/coated paper/adhesive layer/PET film/back primer layer/back layer.

<Coating solution for adhesive layer>
Urethane resin 30 parts (Takelac (registered trademark) A-969V, Mitsui Chemicals, Inc.)
Isocyanate 10 parts (Takenate (registered trademark) A-5, Mitsui Chemicals, Inc.)
・Ethyl acetate 60 parts

<Coating solution for primer layer>
Polyester 4.2 parts (Nichigo Polyester (registered trademark) WR-905, Mitsubishi Chemical Corporation)
Titanium dioxide 8.4 parts (TCA-888, Tochem Products Co., Ltd.)
Fluorescent whitening agent 0.07 parts (UBITEX (registered trademark) BAC, BASF Japan)
7.2 parts isopropyl alcohol 21 parts water

<Coating solution for receiving layer>
Vinyl chloride-vinyl acetate copolymer 12 parts (Solvine (registered trademark) C, Nissin Chemical Industry Co., Ltd.)
Epoxy modified silicone 0.8 parts (X-22-3000T, Shin-Etsu Chemical Co., Ltd.)
Amino-modified silicone 0.24 parts (X-22-1660B-3, Shin-Etsu Chemical Co., Ltd.)
・Toluene 30 parts ・Methyl ethyl ketone 30 parts

<Coating solution for back layer>
Polyvinyl butyral 10 parts (S-LEC (registered trademark) BL-7, Sekisui Chemical Co., Ltd.)
Silicon dioxide 0.75 parts (Silysia 380, Fuji Silysia Chemical Co., Ltd.)
Titanium chelate compound 0.117 parts (AT chelating agent, Denka Polymer Co., Ltd.)
・Toluene 40 parts ・Methyl ethyl ketone 40 parts

[Examples 2 to 8, Comparative Examples 1 to 5]
A thermal transfer image receiving sheet was prepared in the same manner as in Example 1, except that at least one of the type of resin film constituting the laminated substrate, the type of coating liquid for the back primer layer, the thickness and PV ratio of the back primer layer, and the thickness of the back layer was changed as shown in Table 2.

The substrates (resin films) listed in Table 2 are as follows.
PET: Polyethylene terephthalate film
(Lumirror (registered trademark) T-60, thickness 25 μm, Toray Industries, Inc.)
OPP: Biaxially oriented polypropylene film
(PA30, thickness 30 μm, Sun Tox Co., Ltd.)

[Evaluation of Thermal Transfer Image Receiving Sheet]
The thermal transfer image-receiving sheets prepared in the Examples and Comparative Examples were evaluated as follows.
<Abrasion resistance>
With reference to the drying test of JIS L0849, the abrasion resistance of the back layer of the thermal transfer image receiving sheet was tested under the following measurement conditions using an "Friction Tester FR-II" (Suga Test Instruments Co., Ltd., a Gakushin-type abrasion fastness tester specified in JIS L0849) and the sample was visually inspected for scratches after the test.
(Measurement conditions)
・Sample size: 220mm x 30mm
Load: 200g
・Frictional element reciprocation speed: 30 reciprocations per minute ・Number of reciprocations of the frictional element: 20 reciprocations or 100 reciprocations (criteria for evaluation)
A: No scratches were found after 100 round trips.
B: No scratches were found after 20 round trips, but scratches were found after 100 round trips.
C: Scratches were found after 20 round trips, and problems were encountered in practical use.

<Double feeding and backside transport scratches>
Using a dye-sublimation thermal transfer printer (Model: Xiaomi MIJIA Photo Printer, manufactured by Xiaomi Inc.), 20 black solid images were printed on the thermal transfer image-receiving sheet to obtain printed matter.

The occurrence of double feeding during printing was evaluated according to the following criteria.
(Judgment criteria)
◯: The thermal transfer image receiving sheets (printed matter) were not conveyed overlapping each other and were discharged satisfactorily.
x: Thermal transfer image receiving sheets (printed matter) were discharged overlapping each other.

The back surface layer of the printed matter was visually inspected for scratches caused during transportation.
・〇: No scratches were found during transportation.
・×: Scratches during transportation were observed.

<Backside writing ability>
Writing was done on the back surface layer of the thermal transfer image receiving sheet with a water-based ballpoint pen, and after one minute, the back surface layer was rubbed with Bencotton and visually observed to see whether the written characters had faded or not.
・Good: The letters did not fade when rubbed with Bencotton.
・×: The letters became faint when rubbed with Bencotton.

<Concealment>
The defects of the coated paper and the back side substrate were visually confirmed from the back side of the thermal transfer image receiving sheet. Here, the defects refer to foreign matter, fish eyes, etc. that are thought to have occurred during the production of the coated paper and the back side substrate. If no defects were found, it can be said that the concealment by the back primer layer is high.
(Judgment criteria)
A: No defects were identified.
B: Defects were identified, but they were minor and did not pose a problem in practical use.
C: Defects were identified, and problems arose in practical use.

The results of each of the above evaluations are shown in Table 2.

1: Thermal transfer image receiving sheet 10: Substrate 12: Back primer layer 14: Back layer 16: Heat insulating layer 18: Primer layer 20: Receiving layer 2: Printed matter 22: Protective layer

Claims (9)

A thermal transfer image receiving sheet comprising a back surface layer, a back surface primer layer, a substrate, and a receiving layer in this order,
the back surface primer layer contains a pigment and a resin material containing a urethane resin component,
a mass ratio of the pigment content to the resin material content in the back primer layer (pigment content/resin material content) is 1.00 or more and 3.00 or less;
The thickness of the back primer layer is 0.20 μm or more and 0.90 μm or less.
Thermal transfer image receiving sheet. The thermal transfer image receiving sheet according to claim 1, wherein the thickness of the back layer is 0.05 μm or more and 2.00 μm or less. The thermal transfer image receiving sheet according to claim 1 or 2, wherein the urethane resin component is at least one selected from a urethane resin and a crosslinked product of the urethane resin with an isocyanate-based crosslinking agent. The thermal transfer image receiving sheet according to claim 3, wherein the urethane resin has a softening point of 80°C or higher and 100°C or lower. The thermal transfer image receiving sheet according to claim 3 or 4, wherein the urethane resin has a glass transition temperature of -28°C or higher and 5°C or lower. (1) preparing a thermal transfer image receiving sheet according to any one of claims 1 to 5;
(2) A method for producing a printed matter, comprising the step of forming an image on the receiving layer of the thermal transfer image receiving sheet. (3) The method for producing a print according to claim 6, further comprising a step of forming a protective layer on the receiving layer on which the image is formed. A thermal transfer image receiving sheet according to any one of claims 1 to 5,
and an image formed on the receiving layer of the thermal transfer image receiving sheet. The print according to claim 8, further comprising a protective layer on the receiving layer on which the image is formed.

Images